Adding upstream version 1:2.3.19.1+dfsg1.upstream/1%2.3.19.1+dfsg1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

76 files changed, 18693 insertions, 0 deletions

diff --git a/src/imap/Makefile.am b/src/imap/Makefile.am
new file mode 100644
index 0000000..0a45fd3
--- /dev/null
+++ b/src/imap/Makefile.am
@@ -0,0 +1,130 @@
+pkglibexecdir = $(libexecdir)/dovecot
+
+pkglibexec_PROGRAMS = imap
+
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/src/lib \
+	-I$(top_srcdir)/src/lib-test \
+	-I$(top_srcdir)/src/lib-settings \
+	-I$(top_srcdir)/src/lib-dict \
+	-I$(top_srcdir)/src/lib-master \
+	-I$(top_srcdir)/src/lib-mail \
+	-I$(top_srcdir)/src/lib-smtp \
+	-I$(top_srcdir)/src/lib-imap \
+	-I$(top_srcdir)/src/lib-imap-urlauth \
+	-I$(top_srcdir)/src/lib-imap-storage \
+	-I$(top_srcdir)/src/lib-index \
+	-I$(top_srcdir)/src/lib-storage \
+	$(BINARY_CFLAGS)
+
+imap_LDFLAGS = -export-dynamic \
+	$(BINARY_LDFLAGS)
+
+imap_LDADD = \
+	../lib-imap-urlauth/libimap-urlauth.la \
+	$(LIBDOVECOT_STORAGE) \
+	$(LIBDOVECOT)
+imap_DEPENDENCIES = \
+	../lib-imap-urlauth/libimap-urlauth.la \
+	$(LIBDOVECOT_STORAGE_DEPS) \
+	$(LIBDOVECOT_DEPS)
+
+cmds = \
+	cmd-append.c \
+	cmd-capability.c \
+	cmd-cancelupdate.c \
+	cmd-check.c \
+	cmd-close.c \
+	cmd-copy.c \
+	cmd-create.c \
+	cmd-delete.c \
+	cmd-enable.c \
+	cmd-examine.c \
+	cmd-expunge.c \
+	cmd-fetch.c \
+	cmd-genurlauth.c \
+	cmd-getmetadata.c \
+	cmd-id.c \
+	cmd-idle.c \
+	cmd-list.c \
+	cmd-logout.c \
+	cmd-lsub.c \
+	cmd-namespace.c \
+	cmd-noop.c \
+	cmd-notify.c \
+	cmd-rename.c \
+	cmd-resetkey.c \
+	cmd-search.c \
+	cmd-select.c \
+	cmd-setmetadata.c \
+	cmd-sort.c \
+	cmd-status.c \
+	cmd-store.c \
+	cmd-subscribe.c \
+	cmd-thread.c \
+	cmd-unselect.c \
+	cmd-unsubscribe.c \
+	cmd-urlfetch.c \
+	cmd-x-cancel.c \
+	cmd-x-state.c
+
+common_sources = \
+	$(cmds) \
+	imap-client.c \
+	imap-client-hibernate.c \
+	imap-commands.c \
+	imap-commands-util.c \
+	imap-expunge.c \
+	imap-feature.c \
+	imap-fetch.c \
+	imap-fetch-body.c \
+	imap-list.c \
+	imap-master-client.c \
+	imap-notify.c \
+	imap-search.c \
+	imap-search-args.c \
+	imap-settings.c \
+	imap-status.c \
+	imap-state.c \
+	imap-sync.c \
+	mail-storage-callbacks.c
+
+imap_SOURCES = \
+	$(common_sources) \
+	main.c
+
+headers = \
+	imap-client.h \
+	imap-commands.h \
+	imap-commands-util.h \
+	imap-common.h \
+	imap-expunge.h \
+	imap-feature.h \
+	imap-fetch.h \
+	imap-list.h \
+	imap-master-client.h \
+	imap-notify.h \
+	imap-search.h \
+	imap-search-args.h \
+	imap-settings.h \
+	imap-status.h \
+	imap-state.h \
+	imap-sync.h \
+	imap-sync-private.h
+
+pkginc_libdir=$(pkgincludedir)
+pkginc_lib_HEADERS = $(headers)
+
+test_programs = \
+	test-imap-client-hibernate
+noinst_PROGRAMS = $(test_programs)
+
+test_imap_client_hibernate_SOURCES = \
+	test-imap-client-hibernate.c $(common_sources)
+test_imap_client_hibernate_LDADD = $(imap_LDADD)
+test_imap_client_hibernate_DEPENDENCIES = $(imap_DEPENDENCIES)
+
+check-local:
+	for bin in $(test_programs); do \
+	  if ! $(RUN_TEST) ./$$bin; then exit 1; fi; \
+	done
diff --git a/src/imap/Makefile.in b/src/imap/Makefile.in
new file mode 100644
index 0000000..df12ec1
--- /dev/null
+++ b/src/imap/Makefile.in
@@ -0,0 +1,1213 @@
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+AM_CPPFLAGS = \
+	-I$(top_srcdir)/src/lib \
+	-I$(top_srcdir)/src/lib-test \
+	-I$(top_srcdir)/src/lib-settings \
+	-I$(top_srcdir)/src/lib-dict \
+	-I$(top_srcdir)/src/lib-master \
+	-I$(top_srcdir)/src/lib-mail \
+	-I$(top_srcdir)/src/lib-smtp \
+	-I$(top_srcdir)/src/lib-imap \
+	-I$(top_srcdir)/src/lib-imap-urlauth \
+	-I$(top_srcdir)/src/lib-imap-storage \
+	-I$(top_srcdir)/src/lib-index \
+	-I$(top_srcdir)/src/lib-storage \
+	$(BINARY_CFLAGS)
+
+imap_LDFLAGS = -export-dynamic \
+	$(BINARY_LDFLAGS)
+
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+	../lib-imap-urlauth/libimap-urlauth.la \
+	$(LIBDOVECOT_STORAGE) \
+	$(LIBDOVECOT)
+
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+	../lib-imap-urlauth/libimap-urlauth.la \
+	$(LIBDOVECOT_STORAGE_DEPS) \
+	$(LIBDOVECOT_DEPS)
+
+cmds = \
+	cmd-append.c \
+	cmd-capability.c \
+	cmd-cancelupdate.c \
+	cmd-check.c \
+	cmd-close.c \
+	cmd-copy.c \
+	cmd-create.c \
+	cmd-delete.c \
+	cmd-enable.c \
+	cmd-examine.c \
+	cmd-expunge.c \
+	cmd-fetch.c \
+	cmd-genurlauth.c \
+	cmd-getmetadata.c \
+	cmd-id.c \
+	cmd-idle.c \
+	cmd-list.c \
+	cmd-logout.c \
+	cmd-lsub.c \
+	cmd-namespace.c \
+	cmd-noop.c \
+	cmd-notify.c \
+	cmd-rename.c \
+	cmd-resetkey.c \
+	cmd-search.c \
+	cmd-select.c \
+	cmd-setmetadata.c \
+	cmd-sort.c \
+	cmd-status.c \
+	cmd-store.c \
+	cmd-subscribe.c \
+	cmd-thread.c \
+	cmd-unselect.c \
+	cmd-unsubscribe.c \
+	cmd-urlfetch.c \
+	cmd-x-cancel.c \
+	cmd-x-state.c
+
+common_sources = \
+	$(cmds) \
+	imap-client.c \
+	imap-client-hibernate.c \
+	imap-commands.c \
+	imap-commands-util.c \
+	imap-expunge.c \
+	imap-feature.c \
+	imap-fetch.c \
+	imap-fetch-body.c \
+	imap-list.c \
+	imap-master-client.c \
+	imap-notify.c \
+	imap-search.c \
+	imap-search-args.c \
+	imap-settings.c \
+	imap-status.c \
+	imap-state.c \
+	imap-sync.c \
+	mail-storage-callbacks.c
+
+imap_SOURCES = \
+	$(common_sources) \
+	main.c
+
+headers = \
+	imap-client.h \
+	imap-commands.h \
+	imap-commands-util.h \
+	imap-common.h \
+	imap-expunge.h \
+	imap-feature.h \
+	imap-fetch.h \
+	imap-list.h \
+	imap-master-client.h \
+	imap-notify.h \
+	imap-search.h \
+	imap-search-args.h \
+	imap-settings.h \
+	imap-status.h \
+	imap-state.h \
+	imap-sync.h \
+	imap-sync-private.h
+
+pkginc_libdir = $(pkgincludedir)
+pkginc_lib_HEADERS = $(headers)
+test_programs = \
+	test-imap-client-hibernate
+
+test_imap_client_hibernate_SOURCES = \
+	test-imap-client-hibernate.c $(common_sources)
+
+test_imap_client_hibernate_LDADD = $(imap_LDADD)
+test_imap_client_hibernate_DEPENDENCIES = $(imap_DEPENDENCIES)
+all: all-am
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+	if test -n "$$list"; then \
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+	  $(MKDIR_P) "$(DESTDIR)$(pkglibexecdir)" || exit 1; \
+	fi; \
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+	    $(INSTALL_PROGRAM_ENV) $(LIBTOOL) $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=install $(INSTALL_PROGRAM) $$files "$(DESTDIR)$(pkglibexecdir)$$dir" || exit $$?; \
+	    } \
+	; done
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+uninstall-pkglibexecPROGRAMS:
+	@$(NORMAL_UNINSTALL)
+	@list='$(pkglibexec_PROGRAMS)'; test -n "$(pkglibexecdir)" || list=; \
+	files=`for p in $$list; do echo "$$p"; done | \
+	  sed -e 'h;s,^.*/,,;s/$(EXEEXT)$$//;$(transform)' \
+	      -e 's/$$/$(EXEEXT)/' \
+	`; \
+	test -n "$$list" || exit 0; \
+	echo " ( cd '$(DESTDIR)$(pkglibexecdir)' && rm -f" $$files ")"; \
+	cd "$(DESTDIR)$(pkglibexecdir)" && rm -f $$files
+
+clean-pkglibexecPROGRAMS:
+	@list='$(pkglibexec_PROGRAMS)'; test -n "$$list" || exit 0; \
+	echo " rm -f" $$list; \
+	rm -f $$list || exit $$?; \
+	test -n "$(EXEEXT)" || exit 0; \
+	list=`for p in $$list; do echo "$$p"; done | sed 's/$(EXEEXT)$$//'`; \
+	echo " rm -f" $$list; \
+	rm -f $$list
+
+imap$(EXEEXT): $(imap_OBJECTS) $(imap_DEPENDENCIES) $(EXTRA_imap_DEPENDENCIES) 
+	@rm -f imap$(EXEEXT)
+	$(AM_V_CCLD)$(imap_LINK) $(imap_OBJECTS) $(imap_LDADD) $(LIBS)
+
+test-imap-client-hibernate$(EXEEXT): $(test_imap_client_hibernate_OBJECTS) $(test_imap_client_hibernate_DEPENDENCIES) $(EXTRA_test_imap_client_hibernate_DEPENDENCIES) 
+	@rm -f test-imap-client-hibernate$(EXEEXT)
+	$(AM_V_CCLD)$(LINK) $(test_imap_client_hibernate_OBJECTS) $(test_imap_client_hibernate_LDADD) $(LIBS)
+
+mostlyclean-compile:
+	-rm -f *.$(OBJEXT)
+
+distclean-compile:
+	-rm -f *.tab.c
+
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diff --git a/src/imap/cmd-append.c b/src/imap/cmd-append.c
new file mode 100644
index 0000000..0d0c1c3
--- /dev/null
+++ b/src/imap/cmd-append.c
@@ -0,0 +1,957 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "ioloop.h"
+#include "istream.h"
+#include "istream-chain.h"
+#include "ostream.h"
+#include "str.h"
+#include "imap-resp-code.h"
+#include "istream-binary-converter.h"
+#include "mail-storage-private.h"
+#include "imap-parser.h"
+#include "imap-date.h"
+#include "imap-util.h"
+#include "imap-commands.h"
+#include "imap-msgpart-url.h"
+
+#include <sys/time.h>
+
+/* Don't allow internaldates to be too far in the future. At least with Maildir
+   they can cause problems with incremental backups since internaldate is
+   stored in file's mtime. But perhaps there are also some other reasons why
+   it might not be wanted. */
+#define INTERNALDATE_MAX_FUTURE_SECS (2*3600)
+
+struct cmd_append_context {
+	struct client *client;
+        struct client_command_context *cmd;
+	struct mailbox *box;
+        struct mailbox_transaction_context *t;
+	time_t started;
+
+	struct istream_chain *catchain;
+	uoff_t cat_msg_size;
+
+	struct istream *input;
+	struct istream *litinput;
+	uoff_t literal_size;
+
+	struct imap_parser *save_parser;
+	struct mail_save_context *save_ctx;
+	unsigned int count;
+
+	bool message_input:1;
+	bool binary_input:1;
+	bool catenate:1;
+	bool cmd_args_set:1;
+	bool failed:1;
+};
+
+static void cmd_append_finish(struct cmd_append_context *ctx);
+static bool cmd_append_continue_message(struct client_command_context *cmd);
+static bool cmd_append_parse_new_msg(struct client_command_context *cmd);
+
+static const char *
+get_disconnect_reason(struct cmd_append_context *ctx, uoff_t lit_offset)
+{
+	string_t *str = t_str_new(128);
+	unsigned int secs = ioloop_time - ctx->started;
+
+	str_printfa(str, "%s (While APPENDing: %u msgs, %u secs",
+		    i_stream_get_disconnect_reason(ctx->input),
+		    ctx->count, secs);
+	if (ctx->literal_size > 0) {
+		str_printfa(str, ", %"PRIuUOFF_T"/%"PRIuUOFF_T" bytes",
+			    lit_offset, ctx->literal_size);
+	}
+	str_append_c(str, ')');
+	return str_c(str);
+}
+
+static void client_input_append(struct client_command_context *cmd)
+{
+	struct cmd_append_context *ctx = cmd->context;
+	struct client *client = cmd->client;
+	const char *reason;
+	bool finished;
+	uoff_t lit_offset;
+
+	i_assert(!client->destroyed);
+
+	client->last_input = ioloop_time;
+	timeout_reset(client->to_idle);
+
+	switch (i_stream_read(client->input)) {
+	case -1:
+		/* disconnected */
+		lit_offset = ctx->litinput == NULL ? 0 :
+			ctx->litinput->v_offset;
+		reason = get_disconnect_reason(ctx, lit_offset);
+		cmd_append_finish(cmd->context);
+		/* Reset command so that client_destroy() doesn't try to call
+		   cmd_append_continue_message() anymore. */
+		client_command_free(&cmd);
+		client_destroy(client, reason);
+		return;
+	case -2:
+		if (ctx->message_input) {
+			/* message data, this is handled internally by
+			   mailbox_save_continue() */
+			break;
+		}
+		cmd_append_finish(cmd->context);
+
+		/* parameter word is longer than max. input buffer size.
+		   this is most likely an error, so skip the new data
+		   until newline is found. */
+		client->input_skip_line = TRUE;
+
+		if (!ctx->failed)
+			client_send_command_error(cmd, "Too long argument.");
+		cmd->param_error = TRUE;
+		client_command_free(&cmd);
+		return;
+	}
+
+	o_stream_cork(client->output);
+	finished = command_exec(cmd);
+	if (!finished)
+		(void)client_handle_unfinished_cmd(cmd);
+	else
+		client_command_free(&cmd);
+	cmd_sync_delayed(client);
+	o_stream_uncork(client->output);
+
+	client_continue_pending_input(client);
+}
+
+static void cmd_append_finish(struct cmd_append_context *ctx)
+{
+	if (ctx->save_parser != NULL)
+		imap_parser_unref(&ctx->save_parser);
+
+	i_assert(ctx->client->input_lock == ctx->cmd);
+
+	io_remove(&ctx->client->io);
+	/* we must put back the original flush callback before beginning to
+	   sync (the command is still unfinished at that point) */
+	o_stream_set_flush_callback(ctx->client->output,
+				    client_output, ctx->client);
+
+	i_stream_unref(&ctx->litinput);
+	i_stream_unref(&ctx->input);
+	if (ctx->save_ctx != NULL)
+		mailbox_save_cancel(&ctx->save_ctx);
+	if (ctx->t != NULL)
+		mailbox_transaction_rollback(&ctx->t);
+	if (ctx->box != ctx->cmd->client->mailbox && ctx->box != NULL)
+		mailbox_free(&ctx->box);
+}
+
+static bool cmd_append_send_literal_continue(struct cmd_append_context *ctx)
+{
+	if (ctx->failed) {
+		/* tagline was already sent, we can abort here */
+		return FALSE;
+	}
+
+	o_stream_nsend(ctx->client->output, "+ OK\r\n", 6);
+	o_stream_uncork(ctx->client->output);
+	o_stream_cork(ctx->client->output);
+	return TRUE;
+}
+
+static int
+cmd_append_catenate_mpurl(struct client_command_context *cmd,
+			  const char *caturl, struct imap_msgpart_url *mpurl)
+{
+	struct cmd_append_context *ctx = cmd->context;
+	struct imap_msgpart_open_result mpresult;
+	uoff_t newsize;
+	const char *client_error;
+	int ret;
+
+	/* catenate URL */
+	ret = imap_msgpart_url_read_part(mpurl, &mpresult, &client_error);
+	if (ret < 0) {
+		client_send_box_error(cmd, ctx->box);
+		return -1;
+	}
+	if (ret == 0) {
+		/* invalid url, abort */
+		client_send_tagline(cmd,
+			t_strdup_printf("NO [BADURL %s] %s.",
+					caturl, client_error));
+		return -1;
+	}
+	if (mpresult.size == 0) {
+		/* empty input */
+		return 0;
+	}
+
+	newsize = ctx->cat_msg_size + mpresult.size;
+	if (newsize < ctx->cat_msg_size) {
+		client_send_tagline(cmd,
+			"NO [TOOBIG] Composed message grows too big.");
+		return -1;
+	}
+
+	ctx->cat_msg_size = newsize;
+	/* add this input stream to chain */
+	i_stream_chain_append(ctx->catchain, mpresult.input);
+	/* save by reading the chain stream */
+	do {
+		ret = i_stream_read(mpresult.input);
+		i_assert(ret != 0); /* we can handle only blocking input here */
+	} while (mailbox_save_continue(ctx->save_ctx) == 0 && ret != -1);
+
+	if (mpresult.input->stream_errno != 0) {
+		mailbox_set_critical(ctx->box,
+			"read(%s) failed: %s (for CATENATE URL %s)",
+			i_stream_get_name(mpresult.input),
+			i_stream_get_error(mpresult.input), caturl);
+		client_send_box_error(cmd, ctx->box);
+		ret = -1;
+	} else if (!mpresult.input->eof) {
+		/* save failed */
+		client_send_box_error(cmd, ctx->box);
+		ret = -1;
+	} else {
+		/* all the input must be consumed, so istream-chain's read()
+		   unreferences the stream and we can free its parent mail */
+		i_assert(!i_stream_have_bytes_left(mpresult.input));
+		ret = 0;
+	}
+	return ret;
+}
+
+static int
+cmd_append_catenate_url(struct client_command_context *cmd, const char *caturl)
+{
+	struct cmd_append_context *ctx = cmd->context;
+	struct imap_msgpart_url *mpurl;
+	const char *client_error;
+	int ret;
+
+	if (ctx->failed)
+		return -1;
+
+	ret = imap_msgpart_url_parse(cmd->client->user, cmd->client->mailbox,
+				     caturl, &mpurl, &client_error);
+	if (ret < 0) {
+		client_send_box_error(cmd, ctx->box);
+		return -1;
+	}
+	if (ret == 0) {
+		/* invalid url, abort */
+		client_send_tagline(cmd,
+			t_strdup_printf("NO [BADURL %s] %s.",
+					caturl, client_error));
+		return -1;
+	}
+	ret = cmd_append_catenate_mpurl(cmd, caturl, mpurl);
+	imap_msgpart_url_free(&mpurl);
+	return ret;
+}
+
+static void cmd_append_catenate_text(struct client_command_context *cmd)
+{
+	struct cmd_append_context *ctx = cmd->context;
+
+	if (ctx->literal_size > UOFF_T_MAX - ctx->cat_msg_size &&
+	    !ctx->failed) {
+		client_send_tagline(cmd,
+			"NO [TOOBIG] Composed message grows too big.");
+		ctx->failed = TRUE;
+	}
+
+	/* save the mail */
+	ctx->cat_msg_size += ctx->literal_size;
+	if (ctx->literal_size == 0) {
+		/* zero length literal. RFC doesn't explicitly specify
+		   what should be done with this, so we'll simply
+		   handle it by skipping the empty text part. */
+		ctx->litinput = i_stream_create_from_data("", 0);
+		ctx->litinput->eof = TRUE;
+	} else {
+		ctx->litinput = i_stream_create_limit(cmd->client->input,
+						      ctx->literal_size);
+		i_stream_chain_append(ctx->catchain, ctx->litinput);
+	}
+}
+
+static int
+cmd_append_catenate(struct client_command_context *cmd,
+		    const struct imap_arg *args, bool *nonsync_r)
+{
+	struct cmd_append_context *ctx = cmd->context;
+	const char *catpart;
+
+	*nonsync_r = FALSE;
+
+	/* Handle URLs until a TEXT literal is encountered */
+	while (imap_arg_get_atom(args, &catpart)) {
+		const char *caturl;
+
+		if (strcasecmp(catpart, "URL") == 0 ) {
+			/* URL <url> */ 
+			args++;
+			if (!imap_arg_get_astring(args, &caturl))
+				break;
+			if (cmd_append_catenate_url(cmd, caturl) < 0) {
+				/* delay failure until we can stop
+				   parsing input */
+				ctx->failed = TRUE;
+			}
+		} else if (strcasecmp(catpart, "TEXT") == 0) {
+			/* TEXT <literal> */
+			args++;
+			if (!imap_arg_get_literal_size(args, &ctx->literal_size))
+				break;
+			if (args->literal8 && !ctx->binary_input &&
+			    !ctx->failed) {
+				client_send_tagline(cmd,
+					"NO ["IMAP_RESP_CODE_UNKNOWN_CTE"] "
+					"Binary input allowed only when the first part is binary.");
+				ctx->failed = TRUE;
+			}
+			*nonsync_r = args->type == IMAP_ARG_LITERAL_SIZE_NONSYNC;
+			cmd_append_catenate_text(cmd);
+			return 1;
+		} else {
+			break;
+		}
+		args++;
+	}
+
+	if (IMAP_ARG_IS_EOL(args)) {
+		/* ")" */
+		return 0;
+	}
+	if (!ctx->failed)
+		client_send_command_error(cmd, "Invalid arguments.");
+	return -1;
+}
+
+static void cmd_append_finish_catenate(struct client_command_context *cmd)
+{
+	struct cmd_append_context *ctx = cmd->context;
+
+	i_stream_chain_append_eof(ctx->catchain);
+	i_stream_unref(&ctx->input);
+	ctx->catenate = FALSE;
+	ctx->catchain = NULL;
+
+	if (ctx->failed) {
+		/* APPEND has already failed */
+		if (ctx->save_ctx != NULL)
+			mailbox_save_cancel(&ctx->save_ctx);
+	} else {
+		if (mailbox_save_finish(&ctx->save_ctx) < 0) {
+			client_send_box_error(cmd, ctx->box);
+			ctx->failed = TRUE;
+		}
+	}
+}
+
+static bool catenate_args_can_stop(struct cmd_append_context *ctx,
+				   const struct imap_arg *args)
+{
+	/* eat away literal_sizes from URLs */
+	while (args->type != IMAP_ARG_EOL) {
+		if (imap_arg_atom_equals(args, "TEXT"))
+			return TRUE;
+		if (!imap_arg_atom_equals(args, "URL")) {
+			/* error - handle it later */
+			return TRUE;
+		}
+		args++;
+		if (args->type == IMAP_ARG_LITERAL_SIZE ||
+		    args->type == IMAP_ARG_LITERAL_SIZE_NONSYNC) {
+			if (args->type == IMAP_ARG_LITERAL_SIZE) {
+				if (!cmd_append_send_literal_continue(ctx))
+					return TRUE;
+			}
+			imap_parser_read_last_literal(ctx->save_parser);
+			return FALSE;
+		}
+		args++;
+	}
+	return TRUE;
+}
+
+static bool cmd_append_continue_catenate(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct cmd_append_context *ctx = cmd->context;
+	const struct imap_arg *args;
+	const char *client_error;
+	enum imap_parser_error parse_error;
+	bool nonsync = FALSE;
+	int ret;
+
+	if (cmd->cancel) {
+		/* cancel the command immediately (disconnection) */
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+
+	/* we're parsing inside CATENATE (..) list after handling a TEXT part.
+	   it's fine that this would need to fully fit into input buffer
+	   (although clients attempting to DoS could simply insert an extra
+	   {1+} between the URLs) */
+	do {
+		ret = imap_parser_read_args(ctx->save_parser, 0,
+					    IMAP_PARSE_FLAG_LITERAL_SIZE |
+					    IMAP_PARSE_FLAG_LITERAL8 |
+					    IMAP_PARSE_FLAG_INSIDE_LIST, &args);
+	} while (ret > 0 && !catenate_args_can_stop(ctx, args));
+	if (ret == -1) {
+		client_error = imap_parser_get_error(ctx->save_parser,
+						     &parse_error);
+		switch (parse_error) {
+		case IMAP_PARSE_ERROR_NONE:
+			i_unreached();
+		case IMAP_PARSE_ERROR_LITERAL_TOO_BIG:
+			client_send_line(client, t_strconcat("* BYE ",
+				(client->set->imap_literal_minus ? "[TOOBIG] " : ""),
+				client_error, NULL));
+			client_disconnect(client, client_error);
+			break;
+		default:
+			if (!ctx->failed)
+				client_send_command_error(cmd, client_error);
+		}
+		client->input_skip_line = TRUE;
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+	if (ret < 0) {
+		/* need more data */
+		return FALSE;
+	}
+
+	if ((ret = cmd_append_catenate(cmd, args, &nonsync)) < 0) {
+		/* invalid parameters, abort immediately */
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+
+	if (ret == 0) {
+		/* ")" */
+		cmd_append_finish_catenate(cmd);
+
+		/* last catenate part */
+		imap_parser_reset(ctx->save_parser);
+		cmd->func = cmd_append_parse_new_msg;
+		return cmd_append_parse_new_msg(cmd);
+	}
+
+	/* TEXT <literal> */
+
+	if (!nonsync) {
+		if (!cmd_append_send_literal_continue(ctx)) {
+			cmd_append_finish(ctx);
+			return TRUE;
+		}
+	}
+
+	i_assert(ctx->litinput != NULL);
+	ctx->message_input = TRUE;
+	cmd->func = cmd_append_continue_message;
+	return cmd_append_continue_message(cmd);
+}
+
+static int
+cmd_append_handle_args(struct client_command_context *cmd,
+		       const struct imap_arg *args, bool *nonsync_r)
+{
+	struct client *client = cmd->client;
+	struct cmd_append_context *ctx = cmd->context;
+	const struct imap_arg *flags_list;
+	const struct imap_arg *cat_list = NULL;
+	enum mail_flags flags;
+	const char *const *keywords_list;
+	struct mail_keywords *keywords;
+	struct istream *input;
+	const char *internal_date_str;
+	time_t internal_date;
+	int ret, timezone_offset;
+	bool valid;
+
+	if (!ctx->cmd_args_set) {
+		ctx->cmd_args_set = TRUE;
+		client_args_finished(cmd, args);
+	}
+
+	/* [<flags>] */
+	if (!imap_arg_get_list(args, &flags_list))
+		flags_list = NULL;
+	else
+		args++;
+
+	/* [<internal date>] */
+	if (args->type != IMAP_ARG_STRING)
+		internal_date_str = NULL;
+	else {
+		internal_date_str = imap_arg_as_astring(args);
+		args++;
+	}
+
+	/* <message literal> | CATENATE (..) */
+	valid = FALSE;
+	*nonsync_r = FALSE;
+	ctx->catenate = FALSE;
+	if (imap_arg_get_literal_size(args, &ctx->literal_size)) {
+		*nonsync_r = args->type == IMAP_ARG_LITERAL_SIZE_NONSYNC;
+		ctx->binary_input = args->literal8;
+		valid = TRUE;
+	} else if (!imap_arg_atom_equals(args, "CATENATE")) {
+		/* invalid */
+	} else if (!imap_arg_get_list(++args, &cat_list)) {
+		/* invalid */
+	} else {
+		valid = TRUE;
+		ctx->catenate = TRUE;
+		/* We'll do BINARY conversion only if the CATENATE's first
+		   part is a literal8. If it doesn't and a literal8 is seen
+		   later we'll abort the append with UNKNOWN-CTE. */
+		ctx->binary_input = imap_arg_atom_equals(&cat_list[0], "TEXT") &&
+			cat_list[1].literal8;
+
+	}
+	if (!IMAP_ARG_IS_EOL(&args[1]))
+		valid = FALSE;
+	if (!valid) {
+		client->input_skip_line = TRUE;
+		if (!ctx->failed)
+			client_send_command_error(cmd, "Invalid arguments.");
+		return -1;
+	}
+
+	if (flags_list == NULL || ctx->failed) {
+		flags = 0;
+		keywords = NULL;
+	} else {
+		if (!client_parse_mail_flags(cmd, flags_list,
+					     &flags, &keywords_list))
+			return -1;
+		if (keywords_list == NULL)
+			keywords = NULL;
+		else if (mailbox_keywords_create(ctx->box, keywords_list,
+						 &keywords) < 0) {
+			/* invalid keywords - delay failure */
+			client_send_box_error(cmd, ctx->box);
+			ctx->failed = TRUE;
+			keywords = NULL;
+		}
+	}
+
+	if (internal_date_str == NULL || ctx->failed) {
+		/* no time given, default to now. */
+		internal_date = (time_t)-1;
+		timezone_offset = 0;
+	} else if (!imap_parse_datetime(internal_date_str,
+					&internal_date, &timezone_offset)) {
+		client_send_command_error(cmd, "Invalid internal date.");
+		if (keywords != NULL)
+			mailbox_keywords_unref(&keywords);
+		return -1;
+	}
+
+	if (internal_date != (time_t)-1 &&
+	    internal_date > ioloop_time + INTERNALDATE_MAX_FUTURE_SECS) {
+		/* the client specified a time in the future, set it to now. */
+		internal_date = (time_t)-1;
+		timezone_offset = 0;
+	}
+
+	if (cat_list != NULL) {
+		ctx->cat_msg_size = 0;
+		ctx->input = i_stream_create_chain(&ctx->catchain,
+						   IO_BLOCK_SIZE);
+	} else {
+		if (ctx->literal_size == 0) {
+			/* no message data, abort */
+			if (!ctx->failed) {
+				client_send_tagline(cmd,
+					"NO Can't save a zero byte message.");
+				ctx->failed = TRUE;
+			}
+			if (!*nonsync_r) {
+				if (keywords != NULL)
+					mailbox_keywords_unref(&keywords);
+				return -1;
+			}
+			/* {0+} used. although there isn't any point in using
+			   MULTIAPPEND here and adding more messages, it is
+			   technically valid so we'll continue parsing.. */
+		}
+		ctx->litinput = i_stream_create_limit(client->input, ctx->literal_size);
+		ctx->input = ctx->litinput;
+		i_stream_ref(ctx->input);
+	}
+	if (ctx->binary_input) {
+		input = i_stream_create_binary_converter(ctx->input);
+		i_stream_unref(&ctx->input);
+		ctx->input = input;
+	}
+
+	if (!ctx->failed) {
+		/* save the mail */
+		ctx->save_ctx = mailbox_save_alloc(ctx->t);
+		mailbox_save_set_flags(ctx->save_ctx, flags, keywords);
+		mailbox_save_set_received_date(ctx->save_ctx,
+					       internal_date, timezone_offset);
+		if (mailbox_save_begin(&ctx->save_ctx, ctx->input) < 0) {
+			/* save initialization failed */
+			client_send_box_error(cmd, ctx->box);
+			ctx->failed = TRUE;
+		}
+	}
+	if (keywords != NULL)
+		mailbox_keywords_unref(&keywords);
+	ctx->count++;
+
+	if (cat_list == NULL) {
+		/* normal APPEND */
+		return 1;
+	} else if (cat_list->type == IMAP_ARG_EOL) {
+		/* zero parts */
+		if (!ctx->failed)
+			client_send_command_error(cmd, "Empty CATENATE list.");
+		client->input_skip_line = TRUE;
+		return -1;
+	} else if ((ret = cmd_append_catenate(cmd, cat_list, nonsync_r)) < 0) {
+		/* invalid parameters, abort immediately */
+		return -1;
+	} else if (ret == 0) {
+		/* CATENATE consisted only of URLs */
+		return 0;
+	} else {
+		/* TEXT part found from CATENATE */
+		return 1;
+	}
+}
+
+static bool cmd_append_finish_parsing(struct client_command_context *cmd)
+{
+	struct cmd_append_context *ctx = cmd->context;
+	enum mailbox_sync_flags sync_flags;
+	enum imap_sync_flags imap_flags;
+	struct mail_transaction_commit_changes changes;
+	unsigned int save_count;
+	string_t *msg;
+	int ret;
+
+	/* eat away the trailing CRLF */
+	cmd->client->input_skip_line = TRUE;
+
+	if (ctx->failed) {
+		/* we failed earlier, error message is sent */
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+	if (ctx->count == 0) {
+		client_send_command_error(cmd, "Missing message size.");
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+
+	ret = mailbox_transaction_commit_get_changes(&ctx->t, &changes);
+	if (ret < 0) {
+		client_send_box_error(cmd, ctx->box);
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+
+	msg = t_str_new(256);
+	save_count = seq_range_count(&changes.saved_uids);
+	if (save_count == 0 || changes.no_read_perm) {
+		/* not supported by backend (virtual) */
+		str_append(msg, "OK Append completed.");
+	} else {
+		i_assert(ctx->count == save_count);
+		str_printfa(msg, "OK [APPENDUID %u ",
+			    changes.uid_validity);
+		imap_write_seq_range(msg, &changes.saved_uids);
+		str_append(msg, "] Append completed.");
+	}
+	ctx->client->append_count += save_count;
+	pool_unref(&changes.pool);
+
+	if (ctx->box == cmd->client->mailbox) {
+		sync_flags = 0;
+		imap_flags = IMAP_SYNC_FLAG_SAFE;
+	} else {
+		sync_flags = MAILBOX_SYNC_FLAG_FAST;
+		imap_flags = 0;
+	}
+
+	cmd_append_finish(ctx);
+	return cmd_sync(cmd, sync_flags, imap_flags, str_c(msg));
+}
+
+static bool cmd_append_args_can_stop(struct cmd_append_context *ctx,
+				     const struct imap_arg *args,
+				     bool *last_literal_r)
+{
+	const struct imap_arg *cat_list;
+
+	*last_literal_r = FALSE;
+	if (args->type == IMAP_ARG_EOL)
+		return TRUE;
+
+	/* [(flags)] ["internal date"] <message literal> | CATENATE (..) */
+	if (args->type == IMAP_ARG_LIST)
+		args++;
+	if (args->type == IMAP_ARG_STRING)
+		args++;
+
+	if (args->type == IMAP_ARG_LITERAL_SIZE ||
+	    args->type == IMAP_ARG_LITERAL_SIZE_NONSYNC)
+		return TRUE;
+	if (imap_arg_atom_equals(args, "CATENATE") &&
+	    imap_arg_get_list(&args[1], &cat_list)) {
+		if (catenate_args_can_stop(ctx, cat_list))
+			return TRUE;
+		*last_literal_r = TRUE;
+	}
+	return FALSE;
+}
+
+static bool cmd_append_parse_new_msg(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct cmd_append_context *ctx = cmd->context;
+	const struct imap_arg *args;
+	const char *client_error;
+	enum imap_parser_error parse_error;
+	unsigned int arg_min_count;
+	bool nonsync, last_literal;
+	int ret;
+
+	/* this function gets called 1) after parsing APPEND <mailbox> and
+	   2) with MULTIAPPEND extension after already saving one or more
+	   mails. */
+	if (cmd->cancel) {
+		/* cancel the command immediately (disconnection) */
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+
+	/* if error occurs, the CRLF is already read. */
+	client->input_skip_line = FALSE;
+
+	/* parse the entire line up to the first message literal, or in case
+	   the input buffer is full of MULTIAPPEND CATENATE URLs, parse at
+	   least until the beginning of the next message */
+	arg_min_count = 0; last_literal = FALSE;
+	do {
+		if (!last_literal)
+			arg_min_count++;
+		else {
+			/* we only read the literal size. now we read the
+			   literal itself. */
+		}
+		ret = imap_parser_read_args(ctx->save_parser, arg_min_count,
+					    IMAP_PARSE_FLAG_LITERAL_SIZE |
+					    IMAP_PARSE_FLAG_LITERAL8, &args);
+	} while (ret >= (int)arg_min_count &&
+		 !cmd_append_args_can_stop(ctx, args, &last_literal));
+	if (ret == -1) {
+		if (!ctx->failed) {
+			client_error = imap_parser_get_error(ctx->save_parser, &parse_error);
+			switch (parse_error) {
+			case IMAP_PARSE_ERROR_NONE:
+				i_unreached();
+			case IMAP_PARSE_ERROR_LITERAL_TOO_BIG:
+				client_send_line(client, t_strconcat("* BYE ",
+					(client->set->imap_literal_minus ? "[TOOBIG] " : ""),
+					client_error, NULL));
+				client_disconnect(client, client_error);
+				break;
+			default:
+				client_send_command_error(cmd, client_error);
+			}
+		}
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+	if (ret < 0) {
+		/* need more data */
+		return FALSE;
+	}
+
+	if (IMAP_ARG_IS_EOL(args)) {
+		/* last message */
+		return cmd_append_finish_parsing(cmd);
+	}
+
+	ret = cmd_append_handle_args(cmd, args, &nonsync);
+	if (ret < 0) {
+		/* invalid parameters, abort immediately */
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+	if (ret == 0) {
+		/* CATENATE contained only URLs. Finish it and see if there
+		   are more messages. */
+		cmd_append_finish_catenate(cmd);
+		imap_parser_reset(ctx->save_parser);
+		return cmd_append_parse_new_msg(cmd);
+	}
+
+	if (!nonsync) {
+		if (!cmd_append_send_literal_continue(ctx)) {
+			cmd_append_finish(ctx);
+			return TRUE;
+		}
+	}
+
+	i_assert(ctx->litinput != NULL);
+	ctx->message_input = TRUE;
+	cmd->func = cmd_append_continue_message;
+	return cmd_append_continue_message(cmd);
+}
+
+static bool cmd_append_continue_message(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct cmd_append_context *ctx = cmd->context;
+	int ret = 0;
+
+	if (cmd->cancel) {
+		/* cancel the command immediately (disconnection) */
+		cmd_append_finish(ctx);
+		return TRUE;
+	}
+
+	if (ctx->save_ctx != NULL) {
+		while (ctx->litinput->v_offset != ctx->literal_size) {
+			ret = i_stream_read(ctx->litinput);
+			if (mailbox_save_continue(ctx->save_ctx) < 0) {
+				/* we still have to finish reading the message
+				   from client */
+				mailbox_save_cancel(&ctx->save_ctx);
+				break;
+			}
+			if (ret == -1 || ret == 0)
+				break;
+		}
+	}
+
+	if (ctx->save_ctx == NULL) {
+		/* saving has already failed, we're just eating away the
+		   literal */
+		(void)i_stream_read(ctx->litinput);
+		i_stream_skip(ctx->litinput,
+			      i_stream_get_data_size(ctx->litinput));
+	}
+
+	if (ctx->litinput->eof || client->input->closed) {
+		uoff_t lit_offset = ctx->litinput->v_offset;
+
+		/* finished - do one more read, to make sure istream-chain
+		   unreferences its stream, which is needed for litinput's
+		   unreferencing to seek the client->input to correct
+		   position. the seek is needed to avoid trying to seek
+		   backwards in the ctx->input's parent stream. */
+		i_stream_seek(ctx->input, ctx->input->v_offset);
+		(void)i_stream_read(ctx->input);
+		i_stream_unref(&ctx->litinput);
+
+		if (ctx->failed) {
+			if (ctx->save_ctx != NULL)
+				mailbox_save_cancel(&ctx->save_ctx);
+		} else if (ctx->save_ctx == NULL) {
+			/* failed above */
+			client_send_box_error(cmd, ctx->box);
+			ctx->failed = TRUE;
+		} else if (lit_offset != ctx->literal_size) {
+			/* client disconnected before it finished sending the
+			   whole message. */
+			ctx->failed = TRUE;
+			mailbox_save_cancel(&ctx->save_ctx);
+			client_disconnect(client,
+				get_disconnect_reason(ctx, lit_offset));
+		} else if (ctx->catenate) {
+			/* CATENATE isn't finished yet */
+		} else if (mailbox_save_finish(&ctx->save_ctx) < 0) {
+			client_send_box_error(cmd, ctx->box);
+			ctx->failed = TRUE;
+		}
+
+		if (client->input->closed) {
+			cmd_append_finish(ctx);
+			return TRUE;
+		}
+
+		/* prepare for the next message (or its part with catenate) */
+		ctx->message_input = FALSE;
+		imap_parser_reset(ctx->save_parser);
+
+		if (ctx->catenate) {
+			cmd->func = cmd_append_continue_catenate;
+			return cmd_append_continue_catenate(cmd);
+		}
+
+		i_stream_unref(&ctx->input);
+		cmd->func = cmd_append_parse_new_msg;
+		return cmd_append_parse_new_msg(cmd);
+	}
+	return FALSE;
+}
+
+bool cmd_append(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+        struct cmd_append_context *ctx;
+	const char *mailbox;
+
+	if (client->syncing) {
+		/* if transaction is created while its view is synced,
+		   appends aren't allowed for it. */
+		cmd->state = CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY;
+		return FALSE;
+	}
+
+	/* <mailbox> */
+	if (!client_read_string_args(cmd, 1, &mailbox))
+		return FALSE;
+
+	/* we keep the input locked all the time */
+	client->input_lock = cmd;
+
+	ctx = p_new(cmd->pool, struct cmd_append_context, 1);
+	ctx->cmd = cmd;
+	ctx->client = client;
+	ctx->started = ioloop_time;
+	if (client_open_save_dest_box(cmd, mailbox, &ctx->box) < 0)
+		ctx->failed = TRUE;
+	else {
+		event_add_str(cmd->global_event, "mailbox",
+			      mailbox_get_vname(ctx->box));
+		ctx->t = mailbox_transaction_begin(ctx->box,
+					MAILBOX_TRANSACTION_FLAG_EXTERNAL |
+					MAILBOX_TRANSACTION_FLAG_ASSIGN_UIDS,
+					imap_client_command_get_reason(cmd));
+	}
+
+	io_remove(&client->io);
+	client->io = io_add_istream(client->input, client_input_append, cmd);
+	/* append is special because we're only waiting on client input, not
+	   client output, so disable the standard output handler until we're
+	   finished */
+	o_stream_unset_flush_callback(client->output);
+
+	ctx->save_parser = imap_parser_create(client->input, client->output,
+					      client->set->imap_max_line_length);
+	if (client->set->imap_literal_minus)
+		imap_parser_enable_literal_minus(ctx->save_parser);
+
+	cmd->func = cmd_append_parse_new_msg;
+	cmd->context = ctx;
+	return cmd_append_parse_new_msg(cmd);
+}
diff --git a/src/imap/cmd-cancelupdate.c b/src/imap/cmd-cancelupdate.c
new file mode 100644
index 0000000..8676567
--- /dev/null
+++ b/src/imap/cmd-cancelupdate.c
@@ -0,0 +1,45 @@
+/* Copyright (c) 2008-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-search.h"
+#include "imap-commands.h"
+
+static bool client_search_update_cancel(struct client *client, const char *tag)
+{
+	struct imap_search_update *update;
+	unsigned int idx;
+
+	update = client_search_update_lookup(client, tag, &idx);
+	if (update == NULL)
+		return FALSE;
+
+	imap_search_update_free(update);
+	array_delete(&client->search_updates, idx, 1);
+	return TRUE;
+}
+
+bool cmd_cancelupdate(struct client_command_context *cmd)
+{
+	const struct imap_arg *args;
+	const char *tag;
+	unsigned int i;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	for (i = 0; args[i].type == IMAP_ARG_STRING; i++) ;
+	if (!IMAP_ARG_IS_EOL(&args[i]) || i == 0) {
+		client_send_command_error(cmd, "Invalid parameters.");
+		return TRUE;
+	}
+
+	while (imap_arg_get_quoted(args, &tag)) {
+		if (!client_search_update_cancel(cmd->client, tag)) {
+			client_send_tagline(cmd, "NO Unknown tag.");
+			return TRUE;
+		}
+		args++;
+	}
+	client_send_tagline(cmd, "OK Updates cancelled.");
+	return TRUE;
+}
diff --git a/src/imap/cmd-capability.c b/src/imap/cmd-capability.c
new file mode 100644
index 0000000..3433c89
--- /dev/null
+++ b/src/imap/cmd-capability.c
@@ -0,0 +1,14 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+#include "str.h"
+
+bool cmd_capability(struct client_command_context *cmd)
+{
+	client_send_line(cmd->client, t_strconcat(
+		"* CAPABILITY ", str_c(cmd->client->capability_string), NULL));
+
+	client_send_tagline(cmd, "OK Capability completed.");
+	return TRUE;
+}
diff --git a/src/imap/cmd-check.c b/src/imap/cmd-check.c
new file mode 100644
index 0000000..a456f7c
--- /dev/null
+++ b/src/imap/cmd-check.c
@@ -0,0 +1,14 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+
+bool cmd_check(struct client_command_context *cmd)
+{
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	return cmd_sync(cmd, MAILBOX_SYNC_FLAG_FULL_READ |
+			MAILBOX_SYNC_FLAG_FULL_WRITE, IMAP_SYNC_FLAG_SAFE,
+			"OK Check completed.");
+}
diff --git a/src/imap/cmd-close.c b/src/imap/cmd-close.c
new file mode 100644
index 0000000..1f4dfeb
--- /dev/null
+++ b/src/imap/cmd-close.c
@@ -0,0 +1,36 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+#include "imap-expunge.h"
+
+bool cmd_close(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct mailbox *mailbox = client->mailbox;
+	struct mail_storage *storage;
+	const char *errstr, *tagged_reply = "OK Close completed.";
+	enum mail_error error = MAIL_ERROR_NONE;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	i_assert(client->mailbox_change_lock == NULL);
+
+	storage = mailbox_get_storage(mailbox);
+	if (imap_expunge(mailbox, NULL, &client->expunged_count) < 0) {
+		errstr = mailbox_get_last_error(mailbox, &error);
+		if (error != MAIL_ERROR_PERM)
+			client_send_untagged_storage_error(client, storage);
+		else {
+			tagged_reply = t_strdup_printf(
+				"OK Closed without expunging: %s", errstr);
+		}
+	}
+	if (mailbox_sync(mailbox, 0) < 0)
+		client_send_untagged_storage_error(client, storage);
+
+	imap_client_close_mailbox(client);
+	client_send_tagline(cmd, tagged_reply);
+	return TRUE;
+}
diff --git a/src/imap/cmd-copy.c b/src/imap/cmd-copy.c
new file mode 100644
index 0000000..1ce018b
--- /dev/null
+++ b/src/imap/cmd-copy.c
@@ -0,0 +1,407 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "istream.h"
+#include "ostream.h"
+#include "imap-resp-code.h"
+#include "imap-util.h"
+#include "imap-commands.h"
+#include "imap-search-args.h"
+
+#include <time.h>
+
+#define COPY_CHECK_INTERVAL 100
+#define MOVE_COMMIT_INTERVAL 1000
+
+struct cmd_copy_context {
+	struct client_command_context *cmd;
+	struct mailbox *srcbox;
+	struct mailbox *destbox;
+	bool move;
+
+	unsigned int copy_count;
+
+	uint32_t uid_validity;
+	ARRAY_TYPE(seq_range) src_uids;
+	ARRAY_TYPE(seq_range) saved_uids;
+	bool hide_saved_uids;
+
+	const char *error_string;
+	enum mail_error mail_error;
+};
+
+static int client_send_sendalive_if_needed(struct client *client)
+{
+	time_t now, last_io;
+	int ret = 0;
+
+	if (o_stream_get_buffer_used_size(client->output) != 0)
+		return 0;
+
+	now = time(NULL);
+	last_io = I_MAX(client->last_input, client->last_output);
+	if (now - last_io > MAIL_STORAGE_STAYALIVE_SECS) {
+		o_stream_nsend_str(client->output, "* OK Hang in there..\r\n");
+		/* make sure it doesn't get stuck on the corked stream */
+		if (o_stream_uncork_flush(client->output) < 0)
+			ret = -1;
+		o_stream_cork(client->output);
+		client->last_output = now;
+	}
+	return ret;
+}
+
+static void copy_update_trashed(struct client *client, struct mailbox *box,
+				unsigned int count)
+{
+	const struct mailbox_settings *set;
+
+	set = mailbox_settings_find(mailbox_get_namespace(box),
+				    mailbox_get_vname(box));
+	if (set != NULL && set->special_use[0] != '\0' &&
+	    str_array_icase_find(t_strsplit_spaces(set->special_use, " "),
+				 "\\Trash"))
+		client->trashed_count += count;
+}
+
+static bool client_is_disconnected(struct client *client)
+{
+	if (client->fd_in == STDIN_FILENO) {
+		/* Skip this check for stdio clients. It's often used in
+		   testing where the test expects that all commands will be
+		   run even though stdin already has reached EOF. */
+		return FALSE;
+	}
+	ssize_t bytes = i_stream_read(client->input);
+	if (bytes == -1)
+		return TRUE;
+	if (bytes != 0)
+		i_stream_set_input_pending(client->input, TRUE);
+	return FALSE;
+}
+
+static int fetch_and_copy(struct cmd_copy_context *copy_ctx,
+			  const struct mail_search_args *uid_search_args)
+{
+	struct client *client = copy_ctx->cmd->client;
+	struct mailbox_transaction_context *t, *src_trans;
+	struct mail_search_args *search_args;
+	struct mail_search_context *search_ctx;
+	struct mail_save_context *save_ctx;
+	struct mail *mail;
+	const char *cmd_reason;
+	struct mail_transaction_commit_changes changes;
+	ARRAY_TYPE(seq_range) src_uids;
+	int ret;
+
+	/* convert uidset to seqset */
+	search_args = mail_search_args_dup(uid_search_args);
+	mail_search_args_init(search_args, copy_ctx->srcbox, TRUE, NULL);
+	/* make sure the number of messages didn't already change */
+	i_assert(uid_search_args->args->type == SEARCH_UIDSET);
+	i_assert(search_args->args->type == SEARCH_SEQSET ||
+		 (search_args->args->type == SEARCH_ALL &&
+		  search_args->args->match_not));
+	if (search_args->args->type != SEARCH_SEQSET ||
+	    seq_range_count(&search_args->args->value.seqset) !=
+	    seq_range_count(&uid_search_args->args->value.seqset)) {
+		mail_search_args_unref(&search_args);
+		return 0;
+	}
+
+	i_assert(o_stream_is_corked(client->output) ||
+		 client->output->stream_errno != 0);
+
+	cmd_reason = imap_client_command_get_reason(copy_ctx->cmd);
+	t = mailbox_transaction_begin(copy_ctx->destbox,
+				      MAILBOX_TRANSACTION_FLAG_EXTERNAL |
+				      MAILBOX_TRANSACTION_FLAG_ASSIGN_UIDS,
+				      cmd_reason);
+	/* Refresh source index so expunged mails will be noticed */
+	src_trans = mailbox_transaction_begin(copy_ctx->srcbox,
+					      MAILBOX_TRANSACTION_FLAG_REFRESH,
+					      cmd_reason);
+	search_ctx = mailbox_search_init(src_trans, search_args,
+					 NULL, 0, NULL);
+	mail_search_args_unref(&search_args);
+
+	t_array_init(&src_uids, 64);
+	ret = 1;
+	while (mailbox_search_next(search_ctx, &mail) && ret > 0) {
+		if (mail->expunged) {
+			ret = 0;
+			break;
+		}
+
+		if ((++copy_ctx->copy_count % COPY_CHECK_INTERVAL) == 0) {
+			/* If we're COPYing (not MOVEing), check if client has
+			   already disconnected. If yes, abort the COPY to
+			   avoid client duplicating the COPY again later.
+			   We can detect this as long as the client doesn't
+			   fill the input buffer full. */
+			if (client_send_sendalive_if_needed(client) < 0 ||
+			    (!copy_ctx->move &&
+			     client_is_disconnected(client))) {
+				/* Client disconnected. Use the same failure
+				   code path as if some messages were
+				   expunged. */
+				ret = 0;
+				break;
+			}
+		}
+
+		save_ctx = mailbox_save_alloc(t);
+		mailbox_save_copy_flags(save_ctx, mail);
+
+		if (copy_ctx->move) {
+			if (mailbox_move(&save_ctx, mail) < 0)
+				ret = -1;
+		} else {
+			if (mailbox_copy(&save_ctx, mail) < 0)
+				ret = -1;
+		}
+		if (ret < 0 && mail->expunged)
+			ret = 0;
+
+		if (ret > 0)
+			seq_range_array_add(&src_uids, mail->uid);
+	}
+
+	if (ret < 0) {
+		copy_ctx->error_string =
+			mailbox_get_last_error(copy_ctx->destbox, &copy_ctx->mail_error);
+	}
+	if (mailbox_search_deinit(&search_ctx) < 0 && ret >= 0) {
+		copy_ctx->error_string =
+			mailbox_get_last_error(copy_ctx->srcbox, &copy_ctx->mail_error);
+		ret = -1;
+	}
+
+	/* Do a final check before committing COPY to see if the client has
+	   already disconnected. */
+	if (!copy_ctx->move && client_is_disconnected(client))
+		ret = 0;
+
+	if (ret <= 0)
+		mailbox_transaction_rollback(&t);
+	else if (mailbox_transaction_commit_get_changes(&t, &changes) < 0) {
+		if (mailbox_get_last_mail_error(copy_ctx->destbox) == MAIL_ERROR_EXPUNGED) {
+			/* storage backend didn't notice the expunge until
+			   at commit time. */
+			ret = 0;
+		} else {
+			ret = -1;
+			copy_ctx->error_string =
+				mailbox_get_last_error(copy_ctx->destbox, &copy_ctx->mail_error);
+		}
+	} else {
+		if (changes.no_read_perm)
+			copy_ctx->hide_saved_uids = TRUE;
+
+		if (seq_range_count(&changes.saved_uids) == 0) {
+			/* storage doesn't support returning UIDs */
+			copy_ctx->hide_saved_uids = TRUE;
+		}
+
+		if (copy_ctx->uid_validity == 0)
+			copy_ctx->uid_validity = changes.uid_validity;
+		else if (copy_ctx->uid_validity != changes.uid_validity) {
+			/* UIDVALIDITY unexpectedly changed */
+			copy_ctx->hide_saved_uids = TRUE;
+		}
+		seq_range_array_merge(&copy_ctx->src_uids, &src_uids);
+		seq_range_array_merge(&copy_ctx->saved_uids, &changes.saved_uids);
+
+		i_assert(copy_ctx->copy_count == seq_range_count(&copy_ctx->saved_uids) ||
+			 copy_ctx->hide_saved_uids);
+		copy_update_trashed(client, copy_ctx->destbox, copy_ctx->copy_count);
+		pool_unref(&changes.pool);
+	}
+
+	if (!copy_ctx->move ||
+	    copy_ctx->srcbox == copy_ctx->destbox) {
+		/* copying or moving within the same mailbox
+		   succeeded or failed */
+		if (mailbox_transaction_commit(&src_trans) < 0 && ret >= 0) {
+			copy_ctx->error_string =
+				mailbox_get_last_error(copy_ctx->srcbox, &copy_ctx->mail_error);
+			ret = -1;
+		}
+	} else if (ret <= 0) {
+		/* move failed, don't expunge anything */
+		mailbox_transaction_rollback(&src_trans);
+	} else {
+		/* move succeeded */
+		if (mailbox_transaction_commit(&src_trans) < 0 ||
+		    mailbox_sync(copy_ctx->srcbox,
+				 MAILBOX_SYNC_FLAG_EXPUNGE) < 0) {
+			copy_ctx->error_string =
+				mailbox_get_last_error(copy_ctx->srcbox, &copy_ctx->mail_error);
+			ret = -1;
+		}
+	}
+	return ret;
+}
+
+static void cmd_move_send_untagged(struct cmd_copy_context *copy_ctx,
+				   string_t *msg, string_t *src_uidset)
+{
+	if (array_count(&copy_ctx->saved_uids) == 0)
+		return;
+	str_printfa(msg, "* OK [COPYUID %u %s ",
+		    copy_ctx->uid_validity, str_c(src_uidset));
+	imap_write_seq_range(msg, &copy_ctx->saved_uids);
+	str_append(msg, "] Moved UIDs.");
+	client_send_line(copy_ctx->cmd->client, str_c(msg));
+}
+
+static bool cmd_copy_full(struct client_command_context *cmd, bool move)
+{
+	struct client *client = cmd->client;
+	struct mailbox *destbox;
+        struct mail_search_args *search_args;
+	struct imap_search_seqset_iter *seqset_iter = NULL;
+	const char *messageset, *mailbox;
+	enum mailbox_sync_flags sync_flags = 0;
+	enum imap_sync_flags imap_flags = 0;
+	struct cmd_copy_context copy_ctx;
+	string_t *msg, *src_uidset;
+	int ret;
+
+	/* <message set> <mailbox> */
+	if (!client_read_string_args(cmd, 2, &messageset, &mailbox))
+		return FALSE;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	/* First convert the message set to sequences. This way nonexistent
+	   UIDs are dropped. */
+	ret = imap_search_get_seqset(cmd, messageset, cmd->uid, &search_args);
+	if (ret <= 0)
+		return ret < 0;
+	if (search_args->args->type == SEARCH_ALL) {
+		i_assert(search_args->args->match_not);
+		mail_search_args_unref(&search_args);
+		return cmd_sync(cmd, sync_flags, imap_flags,
+				"OK No messages found.");
+	}
+	/* Convert seqset to uidset. This is required for MOVE to work
+	   correctly, since it opens another view for the source mailbox
+	   that can have different sequences. */
+	imap_search_anyset_to_uidset(cmd, search_args);
+
+	if (client_open_save_dest_box(cmd, mailbox, &destbox) < 0) {
+		mail_search_args_unref(&search_args);
+		return TRUE;
+	}
+
+	i_zero(&copy_ctx);
+	copy_ctx.cmd = cmd;
+	copy_ctx.destbox = destbox;
+	if (destbox == client->mailbox || !move)
+		copy_ctx.srcbox = client->mailbox;
+	else {
+		copy_ctx.srcbox = mailbox_alloc(mailbox_get_namespace(client->mailbox)->list,
+						mailbox_get_vname(client->mailbox), 0);
+		if (mailbox_sync(copy_ctx.srcbox, 0) < 0) {
+			mail_search_args_unref(&search_args);
+			client_send_box_error(cmd, copy_ctx.srcbox);
+			mailbox_free(&copy_ctx.srcbox);
+			mailbox_free(&destbox);
+			return TRUE;
+		}
+	}
+	copy_ctx.move = move;
+	i_array_init(&copy_ctx.src_uids, 8);
+	i_array_init(&copy_ctx.saved_uids, 8);
+
+	if (move) {
+		/* When moving mails, perform the work in batches of
+		   MOVE_COMMIT_INTERVAL. Each such batch has its own
+		   transaction and search query. */
+		seqset_iter = imap_search_seqset_iter_init(search_args,
+			client->messages_count, MOVE_COMMIT_INTERVAL);
+	}
+	do {
+		T_BEGIN {
+			ret = fetch_and_copy(&copy_ctx, search_args);
+		} T_END;
+		if (ret <= 0) {
+			/* failed */
+			break;
+		}
+	} while (seqset_iter != NULL &&
+		 imap_search_seqset_iter_next(seqset_iter));
+	imap_search_seqset_iter_deinit(&seqset_iter);
+	mail_search_args_unref(&search_args);
+
+	src_uidset = t_str_new(256);
+	imap_write_seq_range(src_uidset, &copy_ctx.src_uids);
+
+	msg = t_str_new(256);
+	if (ret <= 0) {
+		if (move && array_count(&copy_ctx.src_uids) > 0) {
+			/* some of the messages were successfully moved */
+			cmd_move_send_untagged(&copy_ctx, msg, src_uidset);
+		}
+	} else if (copy_ctx.copy_count == 0) {
+		str_append(msg, "OK No messages found.");
+	} else if (seq_range_count(&copy_ctx.saved_uids) == 0 ||
+		   copy_ctx.hide_saved_uids) {
+		/* not supported by backend (virtual) or no read permissions
+		   for mailbox */
+		str_append(msg, move ? "OK Move completed." :
+			   "OK Copy completed.");
+	} else if (move) {
+		cmd_move_send_untagged(&copy_ctx, msg, src_uidset);
+		str_truncate(msg, 0);
+		str_append(msg, "OK Move completed.");
+	} else {
+		str_printfa(msg, "OK [COPYUID %u %s ", copy_ctx.uid_validity,
+			    str_c(src_uidset));
+		imap_write_seq_range(msg, &copy_ctx.saved_uids);
+		str_append(msg, "] Copy completed.");
+	}
+
+	array_free(&copy_ctx.src_uids);
+	array_free(&copy_ctx.saved_uids);
+
+	if (destbox != client->mailbox) {
+		if (move)
+			sync_flags |= MAILBOX_SYNC_FLAG_EXPUNGE;
+		else
+			sync_flags |= MAILBOX_SYNC_FLAG_FAST;
+		imap_flags |= IMAP_SYNC_FLAG_SAFE;
+		mailbox_free(&destbox);
+	} else if (move) {
+		sync_flags |= MAILBOX_SYNC_FLAG_EXPUNGE;
+		imap_flags |= IMAP_SYNC_FLAG_SAFE;
+	}
+	if (copy_ctx.srcbox != client->mailbox)
+		mailbox_free(&copy_ctx.srcbox);
+
+	if (ret > 0)
+		return cmd_sync(cmd, sync_flags, imap_flags, str_c(msg));
+	else if (ret == 0) {
+		/* some messages were expunged, sync them */
+		return cmd_sync(cmd, 0, 0,
+			"NO ["IMAP_RESP_CODE_EXPUNGEISSUED"] "
+			"Some of the requested messages no longer exist.");
+	} else {
+		client_send_error(cmd, copy_ctx.error_string,
+				  copy_ctx.mail_error);
+		return TRUE;
+	}
+}
+
+bool cmd_copy(struct client_command_context *cmd)
+{
+	return cmd_copy_full(cmd, FALSE);
+}
+
+bool cmd_move(struct client_command_context *cmd)
+{
+	return cmd_copy_full(cmd, TRUE);
+}
diff --git a/src/imap/cmd-create.c b/src/imap/cmd-create.c
new file mode 100644
index 0000000..2459173
--- /dev/null
+++ b/src/imap/cmd-create.c
@@ -0,0 +1,48 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-resp-code.h"
+#include "mail-namespace.h"
+#include "imap-commands.h"
+
+bool cmd_create(struct client_command_context *cmd)
+{
+	struct mail_namespace *ns;
+	const char *mailbox, *orig_mailbox;
+	struct mailbox *box;
+	bool directory;
+	size_t len;
+
+	/* <mailbox> */
+	if (!client_read_string_args(cmd, 1, &mailbox))
+		return FALSE;
+
+	orig_mailbox = mailbox;
+	ns = client_find_namespace(cmd, &mailbox);
+	if (ns == NULL)
+		return TRUE;
+
+	len = strlen(orig_mailbox);
+	if (len == 0 || orig_mailbox[len-1] != mail_namespace_get_sep(ns))
+		directory = FALSE;
+	else {
+		/* name ends with hierarchy separator - client is just
+		   informing us that it wants to create children under this
+		   mailbox. */
+                directory = TRUE;
+
+		/* drop separator from mailbox. it's already dropped when
+		   WORKAROUND_TB_EXTRA_MAILBOX_SEP is enabled */
+		if (len == strlen(mailbox))
+			mailbox = t_strndup(mailbox, len-1);
+	}
+
+	box = mailbox_alloc(ns->list, mailbox, 0);
+	event_add_str(cmd->global_event, "mailbox", mailbox_get_vname(box));
+	if (mailbox_create(box, NULL, directory) < 0)
+		client_send_box_error(cmd, box);
+	else
+		client_send_tagline(cmd, "OK Create completed.");
+	mailbox_free(&box);
+	return TRUE;
+}
diff --git a/src/imap/cmd-delete.c b/src/imap/cmd-delete.c
new file mode 100644
index 0000000..e095321
--- /dev/null
+++ b/src/imap/cmd-delete.c
@@ -0,0 +1,59 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+
+bool cmd_delete(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct mail_namespace *ns;
+	struct mailbox *box;
+	const char *name, *client_error;
+	enum mail_error error;
+	bool disconnect = FALSE;
+
+	/* <mailbox> */
+	if (!client_read_string_args(cmd, 1, &name))
+		return FALSE;
+
+	ns = client_find_namespace(cmd, &name);
+	if (ns == NULL)
+		return TRUE;
+
+	box = mailbox_alloc(ns->list, name, 0);
+	event_add_str(cmd->global_event, "mailbox", mailbox_get_vname(box));
+	if (mailbox_is_any_inbox(box)) {
+		/* IMAP protocol allows this, but I think it's safer to
+		   not allow it. */
+		mailbox_free(&box);
+		client_send_tagline(cmd, "NO INBOX can't be deleted.");
+		return TRUE;
+	}
+	if (client->mailbox != NULL &&
+	    mailbox_backends_equal(box, client->mailbox)) {
+		/* deleting selected mailbox. close it first */
+		client_search_updates_free(client);
+		mailbox_free(&client->mailbox);
+		disconnect = TRUE;
+	}
+
+	if (mailbox_delete(box) == 0)
+		client_send_tagline(cmd, "OK Delete completed.");
+	else {
+		client_error = mailbox_get_last_error(box, &error);
+		if (error != MAIL_ERROR_EXISTS)
+			client_send_box_error(cmd, box);
+		else {
+			/* mailbox has children */
+			client_send_tagline(cmd, t_strdup_printf("NO %s",
+								 client_error));
+		}
+	}
+	mailbox_free(&box);
+
+	if (disconnect) {
+		client_disconnect_with_error(cmd->client,
+			"Selected mailbox was deleted, have to disconnect.");
+	}
+	return TRUE;
+}
diff --git a/src/imap/cmd-enable.c b/src/imap/cmd-enable.c
new file mode 100644
index 0000000..904d6db
--- /dev/null
+++ b/src/imap/cmd-enable.c
@@ -0,0 +1,35 @@
+/* Copyright (c) 2003-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "imap-feature.h"
+
+bool cmd_enable(struct client_command_context *cmd)
+{
+	const struct imap_arg *args;
+	const char *str;
+	string_t *reply;
+	unsigned int feature_idx;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	reply = t_str_new(64);
+	str_append(reply, "* ENABLED");
+	for (; !IMAP_ARG_IS_EOL(args); args++) {
+		if (!imap_arg_get_atom(args, &str)) {
+			client_send_command_error(cmd, "Invalid arguments.");
+			return TRUE;
+		}
+		if (imap_feature_lookup(str, &feature_idx)) {
+			client_enable(cmd->client, feature_idx);
+			str_append_c(reply, ' ');
+			str_append(reply, t_str_ucase(str));
+		}
+	}
+	if (str_len(reply) > 9)
+		client_send_line(cmd->client, str_c(reply));
+	client_send_tagline(cmd, "OK Enabled.");
+	return TRUE;
+}
+
diff --git a/src/imap/cmd-examine.c b/src/imap/cmd-examine.c
new file mode 100644
index 0000000..4000fa0
--- /dev/null
+++ b/src/imap/cmd-examine.c
@@ -0,0 +1,9 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+
+bool cmd_examine(struct client_command_context *cmd)
+{
+	return cmd_select_full(cmd, TRUE);
+}
diff --git a/src/imap/cmd-expunge.c b/src/imap/cmd-expunge.c
new file mode 100644
index 0000000..7388937
--- /dev/null
+++ b/src/imap/cmd-expunge.c
@@ -0,0 +1,68 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+#include "imap-search-args.h"
+#include "imap-expunge.h"
+
+static bool ATTR_NULL(2)
+cmd_expunge_finish(struct client_command_context *cmd,
+		   struct mail_search_args *search_args)
+{
+	struct client *client = cmd->client;
+	const char *errstr;
+	enum mail_error error = MAIL_ERROR_NONE;
+	int ret;
+
+	ret = imap_expunge(client->mailbox, search_args == NULL ? NULL :
+			   search_args->args, &client->expunged_count);
+	if (search_args != NULL)
+		mail_search_args_unref(&search_args);
+	if (ret < 0) {
+		errstr = mailbox_get_last_error(client->mailbox, &error);
+		if (error != MAIL_ERROR_PERM) {
+			client_send_box_error(cmd, client->mailbox);
+			return TRUE;
+		} else {
+			return cmd_sync(cmd, 0, IMAP_SYNC_FLAG_SAFE,
+				t_strdup_printf("OK Expunge ignored: %s.",
+						errstr));
+		}
+	}
+
+	client->sync_seen_deletes = FALSE;
+	return cmd_sync(cmd, MAILBOX_SYNC_FLAG_EXPUNGE,
+			IMAP_SYNC_FLAG_SAFE, "OK Expunge completed.");
+}
+
+bool cmd_uid_expunge(struct client_command_context *cmd)
+{
+	const struct imap_arg *args;
+	struct mail_search_args *search_args;
+	const char *uidset;
+	int ret;
+
+	if (!client_read_args(cmd, 1, 0, &args))
+		return FALSE;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	if (!imap_arg_get_astring(&args[0], &uidset)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+
+	ret = imap_search_get_seqset(cmd, uidset, TRUE, &search_args);
+	if (ret <= 0)
+		return ret < 0;
+	return cmd_expunge_finish(cmd, search_args);
+}
+
+bool cmd_expunge(struct client_command_context *cmd)
+{
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	return cmd_expunge_finish(cmd, NULL);
+}
diff --git a/src/imap/cmd-fetch.c b/src/imap/cmd-fetch.c
new file mode 100644
index 0000000..35e85d1
--- /dev/null
+++ b/src/imap/cmd-fetch.c
@@ -0,0 +1,391 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "ostream.h"
+#include "imap-resp-code.h"
+#include "imap-commands.h"
+#include "imap-fetch.h"
+#include "imap-search-args.h"
+#include "mail-search.h"
+
+
+static const char *all_macro[] = {
+	"FLAGS", "INTERNALDATE", "RFC822.SIZE", "ENVELOPE", NULL
+};
+static const char *fast_macro[] = {
+	"FLAGS", "INTERNALDATE", "RFC822.SIZE", NULL
+};
+static const char *full_macro[] = {
+	"FLAGS", "INTERNALDATE", "RFC822.SIZE", "ENVELOPE", "BODY", NULL
+};
+
+static bool
+imap_fetch_cmd_init_handler(struct imap_fetch_context *ctx,
+			    struct client_command_context *cmd,
+			    const char *name, const struct imap_arg **args)
+{
+	struct imap_fetch_init_context init_ctx;
+
+	i_zero(&init_ctx);
+	init_ctx.fetch_ctx = ctx;
+	init_ctx.pool = ctx->ctx_pool;
+	init_ctx.name = name;
+	init_ctx.args = *args;
+
+	if (!imap_fetch_init_handler(&init_ctx)) {
+		i_assert(init_ctx.error != NULL);
+		client_send_command_error(cmd, init_ctx.error);
+		return FALSE;
+	}
+	*args = init_ctx.args;
+	return TRUE;
+}
+
+static bool
+fetch_parse_args(struct imap_fetch_context *ctx,
+		 struct client_command_context *cmd,
+		 const struct imap_arg *arg, const struct imap_arg **next_arg_r)
+{
+	const char *str, *const *macro;
+
+	if (cmd->uid) {
+		if (!imap_fetch_cmd_init_handler(ctx, cmd, "UID", &arg))
+			return FALSE;
+	}
+	if (imap_arg_get_atom(arg, &str)) {
+		str = t_str_ucase(str);
+		arg++;
+
+		/* handle macros first */
+		if (strcmp(str, "ALL") == 0)
+			macro = all_macro;
+		else if (strcmp(str, "FAST") == 0)
+			macro = fast_macro;
+		else if (strcmp(str, "FULL") == 0)
+			macro = full_macro;
+		else {
+			macro = NULL;
+			if (!imap_fetch_cmd_init_handler(ctx, cmd, str, &arg))
+				return FALSE;
+		}
+		if (macro != NULL) {
+			while (*macro != NULL) {
+				if (!imap_fetch_cmd_init_handler(ctx, cmd, *macro, &arg))
+					return FALSE;
+				macro++;
+			}
+		}
+		*next_arg_r = arg;
+	} else {
+		*next_arg_r = arg + 1;
+		arg = imap_arg_as_list(arg);
+		if (IMAP_ARG_IS_EOL(arg)) {
+			client_send_command_error(cmd,
+						  "FETCH list is empty.");
+			return FALSE;
+		}
+		while (imap_arg_get_atom(arg, &str)) {
+			str = t_str_ucase(str);
+			arg++;
+			if (!imap_fetch_cmd_init_handler(ctx, cmd, str, &arg))
+				return FALSE;
+		}
+		if (!IMAP_ARG_IS_EOL(arg)) {
+			client_send_command_error(cmd,
+				"FETCH list contains non-atoms.");
+			return FALSE;
+		}
+	}
+	return TRUE;
+}
+
+static bool
+fetch_parse_modifier(struct imap_fetch_context *ctx,
+		     struct client_command_context *cmd,
+		     struct mail_search_args *search_args,
+		     const char *name, const struct imap_arg **args,
+		     bool *send_vanished)
+{
+	const char *str;
+	uint64_t modseq;
+
+	if (strcmp(name, "CHANGEDSINCE") == 0) {
+		if (cmd->client->nonpermanent_modseqs) {
+			client_send_command_error(cmd,
+				"FETCH CHANGEDSINCE can't be used with non-permanent modseqs");
+			return FALSE;
+		}
+		if (!imap_arg_get_atom(*args, &str) ||
+		    str_to_uint64(str, &modseq) < 0) {
+			client_send_command_error(cmd,
+				"Invalid CHANGEDSINCE modseq.");
+			return FALSE;
+		}
+		*args += 1;
+		imap_search_add_changed_since(search_args, modseq);
+		imap_fetch_init_nofail_handler(ctx, imap_fetch_modseq_init);
+		return TRUE;
+	}
+	if (strcmp(name, "VANISHED") == 0 && cmd->uid) {
+		if (!client_has_enabled(ctx->client, imap_feature_qresync)) {
+			client_send_command_error(cmd, "QRESYNC not enabled");
+			return FALSE;
+		}
+		*send_vanished = TRUE;
+		return TRUE;
+	}
+
+	client_send_command_error(cmd, "Unknown FETCH modifier");
+	return FALSE;
+}
+
+static bool
+fetch_parse_modifiers(struct imap_fetch_context *ctx,
+		      struct client_command_context *cmd,
+		      struct mail_search_args *search_args,
+		      const struct imap_arg *args, bool *send_vanished_r)
+{
+	const char *name;
+
+	*send_vanished_r = FALSE;
+
+	while (!IMAP_ARG_IS_EOL(args)) {
+		if (!imap_arg_get_atom(args, &name)) {
+			client_send_command_error(cmd,
+				"FETCH modifiers contain non-atoms.");
+			return FALSE;
+		}
+		args++;
+		if (!fetch_parse_modifier(ctx, cmd, search_args,
+					  t_str_ucase(name),
+					  &args, send_vanished_r))
+			return FALSE;
+	}
+	if (*send_vanished_r &&
+	    (search_args->args->next == NULL ||
+	     search_args->args->next->type != SEARCH_MODSEQ)) {
+		client_send_command_error(cmd,
+			"VANISHED used without CHANGEDSINCE");
+		return FALSE;
+	}
+	return TRUE;
+}
+
+static bool cmd_fetch_finished(struct client_command_context *cmd ATTR_UNUSED)
+{
+	return TRUE;
+}
+
+static bool imap_fetch_is_failed_retry(struct imap_fetch_context *ctx)
+{
+	if (!array_is_created(&ctx->client->fetch_failed_uids) ||
+	    !array_is_created(&ctx->fetch_failed_uids))
+		return FALSE;
+	return seq_range_array_have_common(&ctx->client->fetch_failed_uids,
+					   &ctx->fetch_failed_uids);
+
+}
+
+static void imap_fetch_add_failed_uids(struct imap_fetch_context *ctx)
+{
+	if (!array_is_created(&ctx->fetch_failed_uids))
+		return;
+	if (!array_is_created(&ctx->client->fetch_failed_uids)) {
+		p_array_init(&ctx->client->fetch_failed_uids, ctx->client->pool,
+			     array_count(&ctx->fetch_failed_uids));
+	}
+	seq_range_array_merge(&ctx->client->fetch_failed_uids,
+			      &ctx->fetch_failed_uids);
+}
+
+static bool cmd_fetch_finish(struct imap_fetch_context *ctx,
+			     struct client_command_context *cmd)
+{
+	static const char *ok_message = "OK Fetch completed.";
+	const char *tagged_reply = ok_message;
+	enum mail_error error;
+	bool seen_flags_changed = ctx->state.seen_flags_changed;
+
+	if (ctx->state.skipped_expunged_msgs) {
+		tagged_reply = "OK ["IMAP_RESP_CODE_EXPUNGEISSUED"] "
+			"Some messages were already expunged.";
+	}
+
+	if (imap_fetch_end(ctx) < 0) {
+		const char *client_error;
+
+		if (cmd->client->output->closed) {
+			/* If we're canceling we need to finish this command
+			   or we'll assert crash. But normally we want to
+			   return FALSE so that the disconnect message logs
+			   about this fetch command and that these latest
+			   output bytes are included in it (which wouldn't
+			   happen if we called client_disconnect() here
+			   directly). */
+			cmd->func = cmd_fetch_finished;
+			imap_fetch_free(&ctx);
+			return cmd->cancel;
+		}
+
+		if (ctx->error == MAIL_ERROR_NONE)
+			client_error = mailbox_get_last_error(cmd->client->mailbox, &error);
+		else {
+			client_error = ctx->errstr;
+			error = ctx->error;
+		}
+		if (error == MAIL_ERROR_CONVERSION) {
+			/* BINARY found unsupported Content-Transfer-Encoding */
+			tagged_reply = t_strdup_printf(
+				"NO ["IMAP_RESP_CODE_UNKNOWN_CTE"] %s", client_error);
+		} else if (error == MAIL_ERROR_INVALIDDATA) {
+			/* Content was invalid */
+			tagged_reply = t_strdup_printf(
+				"NO ["IMAP_RESP_CODE_PARSE"] %s", client_error);
+		} else if (cmd->client->set->parsed_fetch_failure != IMAP_CLIENT_FETCH_FAILURE_NO_AFTER ||
+			   imap_fetch_is_failed_retry(ctx)) {
+			/* By default we never want to reply NO to FETCH
+			   requests, because many IMAP clients become confused
+			   about what they should on NO. A disconnection causes
+			   less confusion. */
+			const char *internal_error =
+				mailbox_get_last_internal_error(cmd->client->mailbox, NULL);
+			client_send_line(cmd->client, t_strconcat(
+				"* BYE FETCH failed: ", client_error, NULL));
+			client_disconnect(cmd->client, t_strconcat(
+				"FETCH failed: ", internal_error, NULL));
+			imap_fetch_free(&ctx);
+			return TRUE;
+		} else {
+			/* Use a tagged NO to FETCH failure, but only if client
+			   hasn't repeated the FETCH to the same email (so that
+			   we avoid infinitely retries from client.) */
+			imap_fetch_add_failed_uids(ctx);
+			tagged_reply = t_strdup_printf(
+				"NO ["IMAP_RESP_CODE_SERVERBUG"] %s", client_error);
+		}
+	}
+	imap_fetch_free(&ctx);
+
+	return cmd_sync(cmd,
+			(seen_flags_changed ? 0 : MAILBOX_SYNC_FLAG_FAST) |
+			(cmd->uid ? 0 : MAILBOX_SYNC_FLAG_NO_EXPUNGES), 0,
+			tagged_reply);
+}
+
+static bool cmd_fetch_continue(struct client_command_context *cmd)
+{
+        struct imap_fetch_context *ctx = cmd->context;
+
+	if (imap_fetch_more(ctx, cmd) == 0) {
+		/* unfinished */
+		return FALSE;
+	}
+	return cmd_fetch_finish(ctx, cmd);
+}
+
+static void cmd_fetch_set_reason_codes(struct client_command_context *cmd,
+				       struct imap_fetch_context *ctx)
+{
+	/* Fetching body or header always causes the message to be opened.
+	   Use them as the primary reason. */
+	if ((ctx->fetch_data & MAIL_FETCH_STREAM_BODY) != 0) {
+		event_strlist_append(cmd->global_event, EVENT_REASON_CODE,
+				     "imap:fetch_body");
+		return;
+	}
+	if ((ctx->fetch_data & MAIL_FETCH_STREAM_HEADER) != 0) {
+		event_strlist_append(cmd->global_event, EVENT_REASON_CODE,
+				     "imap:fetch_header");
+		return;
+	}
+
+	/* The rest of these can come from cache. Since especially with
+	   prefetching we can't really know which one of them specifically
+	   triggered opening the mail, just use all of them as the reasons. */
+	if (ctx->fetch_header_fields ||
+	    HAS_ANY_BITS(ctx->fetch_data,
+			 MAIL_FETCH_IMAP_ENVELOPE |
+			 MAIL_FETCH_DATE)) {
+		event_strlist_append(cmd->global_event, EVENT_REASON_CODE,
+				     "imap:fetch_header_fields");
+	}
+	if (HAS_ANY_BITS(ctx->fetch_data,
+			 MAIL_FETCH_IMAP_BODY |
+			 MAIL_FETCH_IMAP_BODYSTRUCTURE)) {
+		event_strlist_append(cmd->global_event, EVENT_REASON_CODE,
+				     "imap:fetch_bodystructure");
+	}
+	if (HAS_ANY_BITS(ctx->fetch_data,
+			 MAIL_FETCH_PHYSICAL_SIZE |
+			 MAIL_FETCH_VIRTUAL_SIZE)) {
+		event_strlist_append(cmd->global_event, EVENT_REASON_CODE,
+				     "imap:fetch_size");
+	}
+}
+
+bool cmd_fetch(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct imap_fetch_context *ctx;
+	const struct imap_arg *args, *next_arg, *list_arg;
+	struct mail_search_args *search_args;
+	struct imap_fetch_qresync_args qresync_args;
+	const char *messageset;
+	bool send_vanished = FALSE;
+	int ret;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	/* <messageset> <field(s)> [(modifiers)] */
+	if (!imap_arg_get_atom(&args[0], &messageset) ||
+	    (args[1].type != IMAP_ARG_LIST && args[1].type != IMAP_ARG_ATOM) ||
+	    (!IMAP_ARG_IS_EOL(&args[2]) && args[2].type != IMAP_ARG_LIST)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+
+	/* UID FETCH VANISHED needs the uidset, so convert it to
+	   sequence set later */
+	ret = imap_search_get_anyset(cmd, messageset, cmd->uid, &search_args);
+	if (ret <= 0)
+		return ret < 0;
+
+	ctx = imap_fetch_alloc(client, cmd->pool,
+			       imap_client_command_get_reason(cmd));
+
+	if (!fetch_parse_args(ctx, cmd, &args[1], &next_arg) ||
+	    (imap_arg_get_list(next_arg, &list_arg) &&
+	     !fetch_parse_modifiers(ctx, cmd, search_args, list_arg,
+				    &send_vanished))) {
+		imap_fetch_free(&ctx);
+		mail_search_args_unref(&search_args);
+		return TRUE;
+	}
+
+	if (send_vanished) {
+		i_zero(&qresync_args);
+		if (imap_fetch_send_vanished(client, client->mailbox,
+					     search_args, &qresync_args) < 0) {
+			mail_search_args_unref(&search_args);
+			return cmd_fetch_finish(ctx, cmd);
+		}
+	}
+
+	cmd_fetch_set_reason_codes(cmd, ctx);
+	imap_fetch_begin(ctx, client->mailbox, search_args);
+	mail_search_args_unref(&search_args);
+
+	if (imap_fetch_more(ctx, cmd) == 0) {
+		/* unfinished */
+		cmd->state = CLIENT_COMMAND_STATE_WAIT_OUTPUT;
+
+		cmd->func = cmd_fetch_continue;
+		cmd->context = ctx;
+		return FALSE;
+	}
+	return cmd_fetch_finish(ctx, cmd);
+}
diff --git a/src/imap/cmd-genurlauth.c b/src/imap/cmd-genurlauth.c
new file mode 100644
index 0000000..2cdbdd1
--- /dev/null
+++ b/src/imap/cmd-genurlauth.c
@@ -0,0 +1,54 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "imap-commands.h"
+#include "imap-quote.h"
+#include "imap-urlauth.h"
+
+bool cmd_genurlauth(struct client_command_context *cmd)
+{
+	const struct imap_arg *args;
+	string_t *response;
+	int ret;
+
+	if (cmd->client->urlauth_ctx == NULL) {
+		client_send_command_error(cmd, "URLAUTH disabled.");
+		return TRUE;
+	}
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	response = t_str_new(1024);
+	str_append(response, "* GENURLAUTH");
+	for (;;) {
+		const char *url_rump, *mechanism, *url, *client_error;
+
+		if (IMAP_ARG_IS_EOL(args))
+			break;
+		if (!imap_arg_get_astring(args++, &url_rump) ||
+		    !imap_arg_get_atom(args++, &mechanism)) {
+			client_send_command_error(cmd, "Invalid arguments.");
+			return FALSE;
+		}
+
+		ret = imap_urlauth_generate(cmd->client->urlauth_ctx,
+					    mechanism, url_rump, &url,
+					    &client_error);
+		if (ret <= 0) {
+			if (ret < 0)
+				client_send_internal_error(cmd);
+			else
+				client_send_command_error(cmd, client_error);
+			return TRUE;
+		}
+
+		str_append_c(response, ' ');
+		imap_append_astring(response, url);
+	}
+
+	client_send_line(cmd->client, str_c(response));
+	client_send_tagline(cmd, "OK GENURLAUTH completed.");
+	return TRUE;
+}
diff --git a/src/imap/cmd-getmetadata.c b/src/imap/cmd-getmetadata.c
new file mode 100644
index 0000000..ec23135
--- /dev/null
+++ b/src/imap/cmd-getmetadata.c
@@ -0,0 +1,559 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "mail-storage-private.h"
+#include "str.h"
+#include "istream.h"
+#include "istream-sized.h"
+#include "ostream.h"
+#include "mailbox-list-iter.h"
+#include "imap-utf7.h"
+#include "imap-quote.h"
+#include "imap-metadata.h"
+
+struct imap_getmetadata_context {
+	struct client_command_context *cmd;
+
+	struct mailbox *box;
+	struct imap_metadata_transaction *trans;
+	struct mailbox_list_iterate_context *list_iter;
+
+	ARRAY_TYPE(const_string) entries;
+	uint32_t maxsize;
+	uoff_t largest_seen_size;
+	unsigned int depth;
+
+	struct istream *cur_stream;
+
+	struct imap_metadata_iter *iter;
+	string_t *iter_entry_prefix;
+
+	string_t *delayed_errors;
+	string_t *last_error_str;
+	enum mail_error last_error;
+
+	unsigned int entry_idx;
+	bool first_entry_sent;
+};
+
+static bool
+cmd_getmetadata_mailbox_iter_next(struct imap_getmetadata_context *ctx);
+
+static bool
+cmd_getmetadata_parse_options(struct imap_getmetadata_context *ctx,
+			      const struct imap_arg *options)
+{
+	const char *value;
+
+	while (!IMAP_ARG_IS_EOL(options)) {
+		if (imap_arg_atom_equals(options, "MAXSIZE")) {
+			options++;
+			if (!imap_arg_get_atom(options, &value) ||
+			    str_to_uint32(value, &ctx->maxsize) < 0) {
+				client_send_command_error(ctx->cmd,
+					"Invalid value for MAXSIZE option");
+				return FALSE;
+			}
+		} else if (imap_arg_atom_equals(options, "DEPTH")) {
+			options++;
+			if (!imap_arg_get_atom(options, &value)) {
+				client_send_command_error(ctx->cmd,
+					"Invalid value for DEPTH option");
+				return FALSE;
+			}
+			if (strcmp(value, "0") == 0)
+				ctx->depth = 0;
+			else if (strcmp(value, "1") == 0)
+				ctx->depth = 1;
+			else if (strcmp(value, "infinity") == 0)
+				ctx->depth = UINT_MAX;
+			else {
+				client_send_command_error(ctx->cmd,
+					"Invalid value for DEPTH option");
+				return FALSE;
+			}
+		} else {
+			client_send_command_error(ctx->cmd, "Unknown option");
+			return FALSE;
+		}
+		options++;
+	}
+	return TRUE;
+}
+
+static bool
+imap_metadata_parse_entry_names(struct imap_getmetadata_context *ctx,
+				const struct imap_arg *entries)
+{
+	const char *value, *client_error;
+
+	p_array_init(&ctx->entries, ctx->cmd->pool, 4);
+	for (; !IMAP_ARG_IS_EOL(entries); entries++) {
+		if (!imap_arg_get_astring(entries, &value)) {
+			client_send_command_error(ctx->cmd, "Entry isn't astring");
+			return FALSE;
+		}
+		if (!imap_metadata_verify_entry_name(value, &client_error)) {
+			client_send_command_error(ctx->cmd, client_error);
+			return FALSE;
+		}
+
+		/* names are case-insensitive so we'll always lowercase them */
+		value = p_strdup(ctx->cmd->pool, t_str_lcase(value));
+		array_push_back(&ctx->entries, &value);
+	}
+	return TRUE;
+}
+
+static string_t *
+metadata_add_entry(struct imap_getmetadata_context *ctx, const char *entry)
+{
+	string_t *str;
+
+	str = t_str_new(64);
+	if (!ctx->first_entry_sent) {
+		string_t *mailbox_mutf7 = t_str_new(64);
+
+		ctx->first_entry_sent = TRUE;
+		str_append(str, "* METADATA ");
+		if (ctx->box == NULL) {
+			/* server metadata reply */
+			str_append(str, "\"\"");
+		} else {
+			if (imap_utf8_to_utf7(mailbox_get_vname(ctx->box), mailbox_mutf7) < 0)
+				i_unreached();
+			imap_append_astring(str, str_c(mailbox_mutf7));
+		}
+		str_append(str, " (");
+
+		/* nothing can be sent until untagged METADATA is finished */
+		ctx->cmd->client->output_cmd_lock = ctx->cmd;
+	} else {
+		str_append_c(str, ' ');
+	}
+	imap_append_astring(str, entry);
+	return str;
+}
+
+static void
+cmd_getmetadata_send_nil_reply(struct imap_getmetadata_context *ctx,
+			       const char *entry)
+{
+	string_t *str;
+
+	/* client requested a specific entry that didn't exist.
+	   we must return it as NIL. */
+	str = metadata_add_entry(ctx, entry);
+	str_append(str, " NIL");
+	o_stream_nsend(ctx->cmd->client->output, str_data(str), str_len(str));
+}
+
+static void
+cmd_getmetadata_handle_error_str(struct imap_getmetadata_context *ctx,
+				 const char *error_string,
+				 enum mail_error error)
+{
+	if (str_len(ctx->last_error_str) > 0) {
+		str_append(ctx->delayed_errors, "* NO ");
+		str_append_str(ctx->delayed_errors, ctx->last_error_str);
+		str_append(ctx->delayed_errors, "\r\n");
+		str_truncate(ctx->last_error_str, 0);
+	}
+	str_append(ctx->last_error_str, error_string);
+	ctx->last_error = error;
+}
+
+static bool
+cmd_getmetadata_handle_error(struct imap_getmetadata_context *ctx)
+{
+	const char *error_string;
+	enum mail_error error;
+
+	error_string = imap_metadata_transaction_get_last_error(ctx->trans, &error);
+	if (error == MAIL_ERROR_NOTPOSSIBLE && ctx->depth > 0) {
+		/* Using DEPTH to iterate children with imap_metadata=no.
+		   Don't return an error, since some of the entries could be
+		   returned successfully. */
+		return FALSE;
+	}
+
+	cmd_getmetadata_handle_error_str(ctx, error_string, error);
+	return TRUE;
+}
+
+static void cmd_getmetadata_send_entry(struct imap_getmetadata_context *ctx,
+				       const char *entry, bool require_reply)
+{
+	struct client *client = ctx->cmd->client;
+	struct mail_attribute_value value;
+	uoff_t value_len;
+	string_t *str;
+
+	if (imap_metadata_get_stream(ctx->trans, entry, &value) < 0) {
+		if (cmd_getmetadata_handle_error(ctx))
+			return;
+	}
+
+	if (value.value != NULL)
+		value_len = strlen(value.value);
+	else if (value.value_stream != NULL) {
+		if (i_stream_get_size(value.value_stream, TRUE, &value_len) < 0) {
+			e_error(client->event,
+				"GETMETADATA %s: i_stream_get_size(%s) failed: %s", entry,
+				i_stream_get_name(value.value_stream),
+				i_stream_get_error(value.value_stream));
+			i_stream_unref(&value.value_stream);
+			cmd_getmetadata_handle_error_str(ctx,
+				MAIL_ERRSTR_CRITICAL_MSG, MAIL_ERROR_TEMP);
+			return;
+		}
+	} else {
+		/* skip nonexistent entries */
+		if (require_reply)
+			cmd_getmetadata_send_nil_reply(ctx, entry);
+		return;
+	}
+
+	if (value_len > ctx->maxsize) {
+		/* value length is larger than specified MAXSIZE,
+		   skip this entry */
+		if (ctx->largest_seen_size < value_len)
+			ctx->largest_seen_size = value_len;
+		i_stream_unref(&value.value_stream);
+		return;
+	}
+
+	str = metadata_add_entry(ctx, entry);
+	if (value.value != NULL) {
+		str_printfa(str, " {%"PRIuUOFF_T"}\r\n%s", value_len, value.value);
+		o_stream_nsend(client->output, str_data(str), str_len(str));
+	} else {
+		str_printfa(str, " ~{%"PRIuUOFF_T"}\r\n", value_len);
+		o_stream_nsend(client->output, str_data(str), str_len(str));
+
+		ctx->cur_stream = i_stream_create_sized(value.value_stream, value_len);
+		i_stream_unref(&value.value_stream);
+	}
+}
+
+static bool
+cmd_getmetadata_stream_continue(struct imap_getmetadata_context *ctx)
+{
+	enum ostream_send_istream_result res;
+
+	o_stream_set_max_buffer_size(ctx->cmd->client->output, 0);
+	res = o_stream_send_istream(ctx->cmd->client->output, ctx->cur_stream);
+	o_stream_set_max_buffer_size(ctx->cmd->client->output, SIZE_MAX);
+
+	switch (res) {
+	case OSTREAM_SEND_ISTREAM_RESULT_FINISHED:
+		return TRUE;
+	case OSTREAM_SEND_ISTREAM_RESULT_WAIT_INPUT:
+		i_unreached();
+	case OSTREAM_SEND_ISTREAM_RESULT_WAIT_OUTPUT:
+		return FALSE;
+	case OSTREAM_SEND_ISTREAM_RESULT_ERROR_INPUT:
+		e_error(ctx->cmd->client->event, "read(%s) failed: %s",
+			i_stream_get_name(ctx->cur_stream),
+			i_stream_get_error(ctx->cur_stream));
+		client_disconnect(ctx->cmd->client,
+				  "Internal GETMETADATA failure");
+		return TRUE;
+	case OSTREAM_SEND_ISTREAM_RESULT_ERROR_OUTPUT:
+		/* client disconnected */
+		return TRUE;
+	}
+	i_unreached();
+}
+
+static int
+cmd_getmetadata_send_entry_tree(struct imap_getmetadata_context *ctx,
+					   const char *entry)
+{
+	struct client *client = ctx->cmd->client;
+
+	if (o_stream_get_buffer_used_size(client->output) >=
+	    CLIENT_OUTPUT_OPTIMAL_SIZE) {
+		if (o_stream_flush(client->output) <= 0) {
+			o_stream_set_flush_pending(client->output, TRUE);
+			return 0;
+		}
+	}
+
+	if (ctx->iter != NULL) {
+		const char *subentry;
+
+		/* DEPTH iteration */
+		do {
+			subentry = imap_metadata_iter_next(ctx->iter);
+			if (subentry == NULL) {
+				/* iteration finished, get to the next entry */
+				if (imap_metadata_iter_deinit(&ctx->iter) < 0) {
+					if (!cmd_getmetadata_handle_error(ctx))
+						i_unreached();
+				}
+				return -1;
+			}
+		} while (ctx->depth == 1 && strchr(subentry, '/') != NULL);
+		entry = t_strconcat(str_c(ctx->iter_entry_prefix), subentry, NULL);
+	}
+	/* send NIL only on depth 0 query */
+	cmd_getmetadata_send_entry(ctx, entry, ctx->depth == 0);
+
+	if (ctx->cur_stream != NULL) {
+		if (!cmd_getmetadata_stream_continue(ctx))
+			return 0;
+		i_stream_unref(&ctx->cur_stream);
+	}
+
+	if (ctx->iter != NULL) {
+		/* already iterating the entry */
+		return 1;
+	} else if (ctx->depth == 0) {
+		/* no iteration for the entry */
+		return -1;
+	} else {
+		/* we just sent the entry root. iterate its children. */
+		str_truncate(ctx->iter_entry_prefix, 0);
+		str_append(ctx->iter_entry_prefix, entry);
+		str_append_c(ctx->iter_entry_prefix, '/');
+
+		ctx->iter = imap_metadata_iter_init(ctx->trans, entry);
+		return 1;
+	}
+}
+
+static void cmd_getmetadata_iter_deinit(struct imap_getmetadata_context *ctx)
+{
+	if (ctx->iter != NULL)
+		(void)imap_metadata_iter_deinit(&ctx->iter);
+	if (ctx->trans != NULL)
+		(void)imap_metadata_transaction_commit(&ctx->trans, NULL, NULL);
+	if (ctx->box != NULL)
+		mailbox_free(&ctx->box);
+	ctx->first_entry_sent = FALSE;
+	ctx->entry_idx = 0;
+}
+
+static void cmd_getmetadata_deinit(struct imap_getmetadata_context *ctx)
+{
+	struct client_command_context *cmd = ctx->cmd;
+
+	cmd_getmetadata_iter_deinit(ctx);
+	cmd->client->output_cmd_lock = NULL;
+
+	if (ctx->list_iter != NULL &&
+	    mailbox_list_iter_deinit(&ctx->list_iter) < 0)
+		client_send_list_error(cmd, cmd->client->user->namespaces->list);
+	else if (ctx->last_error != 0) {
+		i_assert(str_len(ctx->last_error_str) > 0);
+		const char *tagline =
+			imap_get_error_string(cmd, str_c(ctx->last_error_str),
+					      ctx->last_error);
+		client_send_tagline(cmd, tagline);
+	} else if (ctx->largest_seen_size != 0) {
+		client_send_tagline(cmd, t_strdup_printf(
+			"OK [METADATA LONGENTRIES %"PRIuUOFF_T"] "
+			"Getmetadata completed.", ctx->largest_seen_size));
+	} else {
+		client_send_tagline(cmd, "OK Getmetadata completed.");
+	}
+}
+
+static bool cmd_getmetadata_continue(struct client_command_context *cmd)
+{
+	struct imap_getmetadata_context *ctx = cmd->context;
+	const char *const *entries;
+	unsigned int count;
+	int ret;
+
+	if (cmd->cancel) {
+		cmd_getmetadata_deinit(ctx);
+		return TRUE;
+	}
+
+	if (ctx->cur_stream != NULL) {
+		if (!cmd_getmetadata_stream_continue(ctx))
+			return FALSE;
+		i_stream_unref(&ctx->cur_stream);
+	}
+
+	entries = array_get(&ctx->entries, &count);
+	for (; ctx->entry_idx < count; ctx->entry_idx++) {
+		do {
+			T_BEGIN {
+				ret = cmd_getmetadata_send_entry_tree(ctx, entries[ctx->entry_idx]);
+			} T_END;
+			if (ret == 0)
+				return FALSE;
+		} while (ret > 0);
+	}
+	if (ctx->first_entry_sent)
+		o_stream_nsend_str(cmd->client->output, ")\r\n");
+
+	if (str_len(ctx->delayed_errors) > 0) {
+		o_stream_nsend(cmd->client->output,
+			       str_data(ctx->delayed_errors),
+			       str_len(ctx->delayed_errors));
+		str_truncate(ctx->delayed_errors, 0);
+	}
+
+	cmd_getmetadata_iter_deinit(ctx);
+	if (ctx->list_iter != NULL)
+		return cmd_getmetadata_mailbox_iter_next(ctx);
+	cmd_getmetadata_deinit(ctx);
+	return TRUE;
+}
+
+static bool
+cmd_getmetadata_start(struct imap_getmetadata_context *ctx)
+{
+	struct client_command_context *cmd = ctx->cmd;
+
+	if (ctx->depth > 0)
+		ctx->iter_entry_prefix = str_new(cmd->pool, 128);
+	imap_metadata_transaction_validated_only(ctx->trans,
+		!cmd->client->set->imap_metadata);
+
+	if (!cmd_getmetadata_continue(cmd)) {
+		cmd->state = CLIENT_COMMAND_STATE_WAIT_OUTPUT;
+		cmd->func = cmd_getmetadata_continue;
+		return FALSE;
+	}
+	return TRUE;
+}
+
+static bool
+cmd_getmetadata_server(struct imap_getmetadata_context *ctx)
+{
+	ctx->trans = imap_metadata_transaction_begin_server(ctx->cmd->client->user);
+	return cmd_getmetadata_start(ctx);
+}
+
+static int
+cmd_getmetadata_try_mailbox(struct imap_getmetadata_context *ctx,
+			    struct mail_namespace *ns, const char *mailbox)
+{
+	ctx->box = mailbox_alloc(ns->list, mailbox, MAILBOX_FLAG_READONLY);
+	event_add_str(ctx->cmd->global_event, "mailbox",
+		      mailbox_get_vname(ctx->box));
+
+	enum mailbox_existence existence;
+	if (mailbox_exists(ctx->box, TRUE, &existence) < 0) {
+		return -1;
+	} else if (existence == MAILBOX_EXISTENCE_NONE) {
+		const char *err = t_strdup_printf(MAIL_ERRSTR_MAILBOX_NOT_FOUND,
+						  mailbox_get_vname(ctx->box));
+		mail_storage_set_error(ctx->box->storage, MAIL_ERROR_NOTFOUND, err);
+		return -1;
+	}
+
+	ctx->trans = imap_metadata_transaction_begin(ctx->box);
+	return cmd_getmetadata_start(ctx) ? 1 : 0;
+}
+
+static bool
+cmd_getmetadata_mailbox(struct imap_getmetadata_context *ctx,
+			struct mail_namespace *ns, const char *mailbox)
+{
+	int ret;
+
+	ret = cmd_getmetadata_try_mailbox(ctx, ns, mailbox);
+	if (ret < 0) {
+		client_send_box_error(ctx->cmd, ctx->box);
+		mailbox_free(&ctx->box);
+	}
+	return ret != 0;
+}
+
+static bool
+cmd_getmetadata_mailbox_iter_next(struct imap_getmetadata_context *ctx)
+{
+	const struct mailbox_info *info;
+	int ret;
+
+	while ((info = mailbox_list_iter_next(ctx->list_iter)) != NULL) {
+		if ((info->flags & (MAILBOX_NOSELECT | MAILBOX_NONEXISTENT)) != 0)
+			continue;
+		ret = cmd_getmetadata_try_mailbox(ctx, info->ns, info->vname);
+		if (ret > 0) {
+			/* we'll already recursively went through
+			   all the mailboxes (FIXME: ugly and potentially
+			   stack consuming) */
+			return TRUE;
+		} else if (ret == 0) {
+			/* need to send more data later */
+			return FALSE;
+		}
+		T_BEGIN {
+			client_send_line(ctx->cmd->client, t_strdup_printf(
+				"* NO Failed to open mailbox %s: %s",
+				info->vname, mailbox_get_last_error(ctx->box, NULL)));
+		} T_END;
+		mailbox_free(&ctx->box);
+	}
+	cmd_getmetadata_deinit(ctx);
+	return TRUE;
+}
+
+bool cmd_getmetadata(struct client_command_context *cmd)
+{
+	struct imap_getmetadata_context *ctx;
+	struct mail_namespace *ns;
+	const struct imap_arg *args, *options, *entries;
+	const char *mailbox, *entry_name;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	ctx = p_new(cmd->pool, struct imap_getmetadata_context, 1);
+	ctx->cmd = cmd;
+	ctx->maxsize = (uint32_t)-1;
+	ctx->cmd->context = ctx;
+	ctx->delayed_errors = str_new(cmd->pool, 128);
+	ctx->last_error_str = str_new(cmd->pool, 128);
+
+	if (imap_arg_get_list(&args[0], &options)) {
+		if (!cmd_getmetadata_parse_options(ctx, options))
+			return TRUE;
+		args++;
+	}
+	if (!imap_arg_get_astring(&args[0], &mailbox)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+	if (!imap_arg_get_list(&args[1], &entries)) {
+		if (!imap_arg_get_astring(&args[1], &entry_name) ||
+		    !IMAP_ARG_IS_EOL(&args[2])) {
+			client_send_command_error(cmd, "Invalid arguments.");
+			return TRUE;
+		}
+		entries = args+1;
+	}
+	if (!imap_metadata_parse_entry_names(ctx, entries))
+		return TRUE;
+
+	if (mailbox[0] == '\0') {
+		/* server attribute */
+		return cmd_getmetadata_server(ctx);
+	} else if (strchr(mailbox, '*') == NULL &&
+		   strchr(mailbox, '%') == NULL) {
+		/* mailbox attribute */
+		ns = client_find_namespace(cmd, &mailbox);
+		if (ns == NULL)
+			return TRUE;
+		return cmd_getmetadata_mailbox(ctx, ns, mailbox);
+	} else {
+		/* wildcards in mailbox name. this isn't supported by RFC 5464,
+		   but it was in the earlier drafts and is already used by
+		   some software (Horde). */
+		const char *patterns[2];
+		patterns[0] = mailbox; patterns[1] = NULL;
+
+		ctx->list_iter =
+			mailbox_list_iter_init_namespaces(
+				cmd->client->user->namespaces,
+				patterns, MAIL_NAMESPACE_TYPE_MASK_ALL, 0);
+		return cmd_getmetadata_mailbox_iter_next(ctx);
+	}
+}
diff --git a/src/imap/cmd-id.c b/src/imap/cmd-id.c
new file mode 100644
index 0000000..98355d4
--- /dev/null
+++ b/src/imap/cmd-id.c
@@ -0,0 +1,27 @@
+/* Copyright (c) 2008-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-id.h"
+
+bool cmd_id(struct client_command_context *cmd)
+{
+	const struct imap_settings *set = cmd->client->set;
+	const struct imap_arg *args;
+	const char *value;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (!cmd->client->id_logged) {
+		cmd->client->id_logged = TRUE;
+		value = imap_id_args_get_log_reply(args, set->imap_id_log);
+		if (value != NULL)
+			e_info(cmd->client->event, "ID sent: %s", value);
+	}
+
+	client_send_line(cmd->client, t_strdup_printf(
+		"* ID %s", imap_id_reply_generate(set->imap_id_send)));
+	client_send_tagline(cmd, "OK ID completed.");
+	return TRUE;
+}
+
diff --git a/src/imap/cmd-idle.c b/src/imap/cmd-idle.c
new file mode 100644
index 0000000..2b31dc7
--- /dev/null
+++ b/src/imap/cmd-idle.c
@@ -0,0 +1,308 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "istream.h"
+#include "ostream.h"
+#include "crc32.h"
+#include "mail-storage-settings.h"
+#include "imap-commands.h"
+#include "imap-keepalive.h"
+#include "imap-sync.h"
+
+struct cmd_idle_context {
+	struct client *client;
+	struct client_command_context *cmd;
+
+	struct imap_sync_context *sync_ctx;
+	struct timeout *keepalive_to, *to_hibernate;
+
+	bool manual_cork:1;
+	bool sync_pending:1;
+};
+
+static void idle_add_keepalive_timeout(struct cmd_idle_context *ctx);
+static bool cmd_idle_continue(struct client_command_context *cmd);
+
+static void
+idle_finish(struct cmd_idle_context *ctx, bool done_ok, bool free_cmd)
+{
+	struct client *client = ctx->client;
+
+	timeout_remove(&ctx->keepalive_to);
+	timeout_remove(&ctx->to_hibernate);
+
+	if (ctx->sync_ctx != NULL) {
+		/* we're here only in connection failure cases */
+		(void)imap_sync_deinit(ctx->sync_ctx, ctx->cmd);
+	}
+
+	o_stream_cork(client->output);
+	io_remove(&client->io);
+
+	if (client->mailbox != NULL)
+		mailbox_notify_changes_stop(client->mailbox);
+
+	if (done_ok)
+		client_send_tagline(ctx->cmd, "OK Idle completed.");
+	else
+		client_send_tagline(ctx->cmd, "BAD Expected DONE.");
+
+	o_stream_uncork(client->output);
+	if (free_cmd)
+		client_command_free(&ctx->cmd);
+}
+
+static bool
+idle_client_handle_input(struct cmd_idle_context *ctx, bool free_cmd)
+{
+	const char *line;
+
+	while ((line = i_stream_next_line(ctx->client->input)) != NULL) {
+		if (ctx->client->input_skip_line)
+			ctx->client->input_skip_line = FALSE;
+		else {
+			idle_finish(ctx, strcasecmp(line, "DONE") == 0,
+				    free_cmd);
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+static bool idle_client_input_more(struct cmd_idle_context *ctx)
+{
+	struct client *client = ctx->client;
+
+	client->last_input = ioloop_time;
+	timeout_reset(client->to_idle);
+
+	switch (i_stream_read(client->input)) {
+	case -1:
+		/* disconnected */
+		client_disconnect(client, NULL);
+		return TRUE;
+	case -2:
+		client->input_skip_line = TRUE;
+		idle_finish(ctx, FALSE, TRUE);
+		return TRUE;
+	}
+
+	if (ctx->sync_ctx != NULL) {
+		/* we're still sending output to client. wait until it's all
+		   sent so we don't lose any changes. */
+		io_remove(&client->io);
+		return FALSE;
+	}
+
+	return idle_client_handle_input(ctx, TRUE);
+}
+
+static void idle_client_input(struct cmd_idle_context *ctx)
+{
+	struct client *client = ctx->client;
+
+	if (idle_client_input_more(ctx))
+		client_continue_pending_input(client);
+}
+
+static void keepalive_timeout(struct cmd_idle_context *ctx)
+{
+	if (ctx->client->output_cmd_lock != NULL) {
+		/* it's busy sending output */
+		return;
+	}
+
+	if (o_stream_get_buffer_used_size(ctx->client->output) == 0) {
+		/* Sending this keeps NATs/stateful firewalls alive.
+		   Sending this also catches dead connections. Don't send
+		   anything if there is already data waiting in output
+		   buffer. */
+		o_stream_cork(ctx->client->output);
+		client_send_line(ctx->client, "* OK Still here");
+		o_stream_uncork(ctx->client->output);
+	}
+	/* Make sure idling connections don't get disconnected. There are
+	   several clients that really want to IDLE forever and there's not
+	   much harm in letting them do so. */
+	timeout_reset(ctx->client->to_idle);
+	/* recalculate time for the next keepalive timeout */
+	idle_add_keepalive_timeout(ctx);
+}
+
+static bool idle_sync_now(struct mailbox *box, struct cmd_idle_context *ctx)
+{
+	i_assert(ctx->sync_ctx == NULL);
+
+	/* hibernation can't happen while sync is running.
+	   the timeout is added back afterwards. */
+	timeout_remove(&ctx->to_hibernate);
+
+	ctx->sync_pending = FALSE;
+	ctx->sync_ctx = imap_sync_init(ctx->client, box, 0, 0);
+	return cmd_idle_continue(ctx->cmd);
+}
+
+static void idle_callback(struct mailbox *box, struct cmd_idle_context *ctx)
+{
+	struct client *client = ctx->client;
+
+	if (ctx->sync_ctx != NULL)
+		ctx->sync_pending = TRUE;
+	else {
+		ctx->manual_cork = TRUE;
+		(void)idle_sync_now(box, ctx);
+		if (client->disconnected)
+			client_destroy(client, NULL);
+	}
+}
+
+static void idle_add_keepalive_timeout(struct cmd_idle_context *ctx)
+{
+	struct client *client = ctx->client;
+	unsigned int interval = client->set->imap_idle_notify_interval;
+
+	if (interval == 0)
+		return;
+
+	interval = imap_keepalive_interval_msecs(client->user->username,
+						 client->user->conn.remote_ip,
+						 interval);
+
+	timeout_remove(&ctx->keepalive_to);
+	ctx->keepalive_to = timeout_add(interval, keepalive_timeout, ctx);
+}
+
+static void idle_hibernate_timeout(struct cmd_idle_context *ctx)
+{
+	struct client *client = ctx->client;
+	const char *reason;
+
+	i_assert(ctx->sync_ctx == NULL);
+	i_assert(!ctx->sync_pending);
+
+	if (imap_client_hibernate(&client, &reason)) {
+		/* client may be destroyed now */
+	} else {
+		/* failed - don't bother retrying */
+		timeout_remove(&ctx->to_hibernate);
+	}
+}
+
+static void idle_add_hibernate_timeout(struct cmd_idle_context *ctx)
+{
+	unsigned int secs = ctx->client->set->imap_hibernate_timeout;
+
+	i_assert(ctx->to_hibernate == NULL);
+
+	if (secs == 0)
+		return;
+
+	ctx->to_hibernate =
+		timeout_add(secs * 1000, idle_hibernate_timeout, ctx);
+}
+
+static bool cmd_idle_continue(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct cmd_idle_context *ctx = cmd->context;
+	uoff_t orig_offset = client->output->offset;
+
+	if (cmd->cancel) {
+		idle_finish(ctx, FALSE, FALSE);
+		return TRUE;
+	}
+
+	if (ctx->to_hibernate != NULL)
+		timeout_reset(ctx->to_hibernate);
+
+	if (ctx->manual_cork)  {
+		/* we're coming from idle_callback instead of a normal
+		   I/O handler, so we'll have to do corking manually */
+		o_stream_cork(client->output);
+	}
+
+	if (ctx->sync_ctx != NULL) {
+		if (imap_sync_more(ctx->sync_ctx) == 0) {
+			/* unfinished */
+			if (ctx->manual_cork) {
+				ctx->manual_cork = FALSE;
+				o_stream_uncork(client->output);
+			}
+			cmd->state = CLIENT_COMMAND_STATE_WAIT_OUTPUT;
+			return FALSE;
+		}
+
+		if (imap_sync_deinit(ctx->sync_ctx, ctx->cmd) < 0) {
+			client_send_untagged_storage_error(client,
+				mailbox_get_storage(client->mailbox));
+			mailbox_notify_changes_stop(client->mailbox);
+		}
+		ctx->sync_ctx = NULL;
+	}
+	if (client->output->offset != orig_offset &&
+	    ctx->keepalive_to != NULL)
+		idle_add_keepalive_timeout(ctx);
+
+	if (ctx->sync_pending) {
+		/* more changes occurred while we were sending changes to
+		   client.
+
+		   NOTE: this recurses back to this function,
+		   so we return here instead of doing everything twice. */
+		return idle_sync_now(client->mailbox, ctx);
+	}
+	if (ctx->to_hibernate == NULL)
+		idle_add_hibernate_timeout(ctx);
+	cmd->state = CLIENT_COMMAND_STATE_WAIT_INPUT;
+
+	if (ctx->manual_cork) {
+		ctx->manual_cork = FALSE;
+		o_stream_uncork(client->output);
+	}
+
+	if (client->output->closed) {
+		idle_finish(ctx, FALSE, FALSE);
+		return TRUE;
+	}
+	if (client->io == NULL) {
+		/* input is pending. add the io back and mark the input as
+		   pending. we can't safely read more input immediately here. */
+		client->io = io_add_istream(client->input,
+					    idle_client_input, ctx);
+		i_stream_set_input_pending(client->input, TRUE);
+	}
+	return FALSE;
+}
+
+bool cmd_idle(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct cmd_idle_context *ctx;
+
+	ctx = p_new(cmd->pool, struct cmd_idle_context, 1);
+	ctx->cmd = cmd;
+	ctx->client = client;
+	idle_add_keepalive_timeout(ctx);
+	idle_add_hibernate_timeout(ctx);
+
+	if (client->mailbox != NULL)
+		mailbox_notify_changes(client->mailbox, idle_callback, ctx);
+	if (!client->state_import_idle_continue)
+		client_send_line(client, "+ idling");
+	else {
+		/* continuing an IDLE after hibernation */
+		client->state_import_idle_continue = FALSE;
+	}
+
+	io_remove(&client->io);
+	client->io = io_add_istream(client->input, idle_client_input, ctx);
+
+	cmd->func = cmd_idle_continue;
+	cmd->context = ctx;
+
+	/* check immediately if there are changes. if they came before we
+	   added mailbox-notifier, we wouldn't see them otherwise. */
+	if (client->mailbox != NULL)
+		idle_sync_now(client->mailbox, ctx);
+	return idle_client_handle_input(ctx, FALSE);
+}
diff --git a/src/imap/cmd-list.c b/src/imap/cmd-list.c
new file mode 100644
index 0000000..dd6c00e
--- /dev/null
+++ b/src/imap/cmd-list.c
@@ -0,0 +1,484 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "array.h"
+#include "str.h"
+#include "strescape.h"
+#include "mailbox-list-iter.h"
+#include "imap-utf7.h"
+#include "imap-quote.h"
+#include "imap-match.h"
+#include "imap-status.h"
+#include "imap-commands.h"
+#include "imap-list.h"
+
+struct cmd_list_context {
+	struct client_command_context *cmd;
+	struct mail_user *user;
+
+	enum mailbox_list_iter_flags list_flags;
+	struct imap_status_items status_items;
+
+	struct mailbox_list_iterate_context *list_iter;
+
+	bool lsub:1;
+	bool lsub_no_unsubscribed:1;
+	bool used_listext:1;
+	bool used_status:1;
+};
+
+static void
+mailbox_flags2str(struct cmd_list_context *ctx, string_t *str,
+		  const char *special_use, enum mailbox_info_flags flags)
+{
+	size_t orig_len = str_len(str);
+
+	if ((flags & MAILBOX_NONEXISTENT) != 0 && !ctx->used_listext) {
+		flags |= MAILBOX_NOSELECT;
+		flags &= ENUM_NEGATE(MAILBOX_NONEXISTENT);
+	}
+
+	if ((ctx->list_flags & MAILBOX_LIST_ITER_RETURN_CHILDREN) == 0)
+		flags &= ENUM_NEGATE(MAILBOX_CHILDREN | MAILBOX_NOCHILDREN);
+
+	if ((flags & MAILBOX_CHILD_SUBSCRIBED) != 0 &&
+	    (flags & MAILBOX_SUBSCRIBED) == 0 && !ctx->used_listext) {
+		/* LSUB uses \Noselect for this */
+		flags |= MAILBOX_NOSELECT;
+	} else if ((ctx->list_flags & MAILBOX_LIST_ITER_RETURN_SUBSCRIBED) == 0)
+		flags &= ENUM_NEGATE(MAILBOX_SUBSCRIBED);
+	imap_mailbox_flags2str(str, flags);
+
+	if ((ctx->list_flags & MAILBOX_LIST_ITER_RETURN_SPECIALUSE) != 0 &&
+	    special_use != NULL) {
+		if (str_len(str) != orig_len)
+			str_append_c(str, ' ');
+		str_append(str, special_use);
+	}
+}
+
+static void
+mailbox_childinfo2str(struct cmd_list_context *ctx, string_t *str,
+		      enum mailbox_info_flags flags)
+{
+	if (!ctx->used_listext)
+		return;
+
+	if ((flags & MAILBOX_CHILD_SUBSCRIBED) != 0 &&
+	    (ctx->list_flags & MAILBOX_LIST_ITER_SELECT_RECURSIVEMATCH) != 0)
+		str_append(str, " (CHILDINFO (\"SUBSCRIBED\"))");
+	if ((flags & MAILBOX_CHILD_SPECIALUSE) != 0 &&
+	    (ctx->list_flags & MAILBOX_LIST_ITER_SELECT_RECURSIVEMATCH) != 0)
+		str_append(str, " (CHILDINFO (\"SPECIAL-USE\"))");
+}
+
+static bool
+parse_select_flags(struct cmd_list_context *ctx, const struct imap_arg *args)
+{
+	enum mailbox_list_iter_flags list_flags = 0;
+	const char *str;
+
+	while (!IMAP_ARG_IS_EOL(args)) {
+		if (!imap_arg_get_atom(args, &str)) {
+			client_send_command_error(ctx->cmd,
+				"List options contains non-atoms.");
+			return FALSE;
+		}
+
+		if (strcasecmp(str, "SUBSCRIBED") == 0) {
+			list_flags |= MAILBOX_LIST_ITER_SELECT_SUBSCRIBED |
+				MAILBOX_LIST_ITER_RETURN_SUBSCRIBED;
+		} else if (strcasecmp(str, "RECURSIVEMATCH") == 0)
+			list_flags |= MAILBOX_LIST_ITER_SELECT_RECURSIVEMATCH;
+		else if (strcasecmp(str, "SPECIAL-USE") == 0) {
+			list_flags |= MAILBOX_LIST_ITER_SELECT_SPECIALUSE |
+				MAILBOX_LIST_ITER_RETURN_SPECIALUSE;
+		} else if (strcasecmp(str, "REMOTE") == 0) {
+			/* not supported, ignore */
+		} else {
+			/* skip also optional list value */
+			client_send_command_error(ctx->cmd,
+						  "Unknown select options");
+			return FALSE;
+		}
+		args++;
+	}
+
+	if ((list_flags & MAILBOX_LIST_ITER_SELECT_RECURSIVEMATCH) != 0 &&
+	    (list_flags & (MAILBOX_LIST_ITER_SELECT_SUBSCRIBED |
+			   MAILBOX_LIST_ITER_SELECT_SPECIALUSE)) == 0) {
+		client_send_command_error(ctx->cmd,
+			"RECURSIVEMATCH must not be the only selection.");
+		return FALSE;
+	}
+
+	ctx->list_flags = list_flags;
+	return TRUE;
+}
+
+static bool
+parse_return_flags(struct cmd_list_context *ctx, const struct imap_arg *args)
+{
+	enum mailbox_list_iter_flags list_flags = 0;
+	const struct imap_arg *list_args;
+	const char *str;
+
+	while (!IMAP_ARG_IS_EOL(args)) {
+		if (!imap_arg_get_atom(args, &str)) {
+			client_send_command_error(ctx->cmd,
+				"List options contains non-atoms.");
+			return FALSE;
+		}
+
+		if (strcasecmp(str, "SUBSCRIBED") == 0)
+			list_flags |= MAILBOX_LIST_ITER_RETURN_SUBSCRIBED;
+		else if (strcasecmp(str, "CHILDREN") == 0)
+			list_flags |= MAILBOX_LIST_ITER_RETURN_CHILDREN;
+		else if (strcasecmp(str, "SPECIAL-USE") == 0)
+			list_flags |= MAILBOX_LIST_ITER_RETURN_SPECIALUSE;
+		else if (strcasecmp(str, "STATUS") == 0 &&
+			 imap_arg_get_list(&args[1], &list_args)) {
+			if (imap_status_parse_items(ctx->cmd, list_args,
+						    &ctx->status_items) < 0)
+				return FALSE;
+			ctx->used_status = TRUE;
+			args++;
+		} else {
+			/* skip also optional list value */
+			client_send_command_error(ctx->cmd,
+						  "Unknown return options");
+			return FALSE;
+		}
+		args++;
+	}
+
+	ctx->list_flags |= list_flags;
+	return TRUE;
+}
+
+static const char *ns_prefix_mutf7(struct mail_namespace *ns)
+{
+	string_t *str;
+
+	if (*ns->prefix == '\0')
+		return "";
+
+	str = t_str_new(64);
+	if (imap_utf8_to_utf7(ns->prefix, str) < 0)
+		i_panic("Namespace prefix not UTF-8: %s", ns->prefix);
+	return str_c(str);
+}
+
+static void list_reply_append_ns_sep_param(string_t *str, char sep)
+{
+	str_append_c(str, '"');
+	if (sep == '\\')
+		str_append(str, "\\\\");
+	else
+		str_append_c(str, sep);
+	str_append_c(str, '"');
+}
+
+static void
+list_send_status(struct cmd_list_context *ctx, const char *name,
+		 const char *mutf7_name, enum mailbox_info_flags flags)
+{
+	struct imap_status_result result;
+	struct mail_namespace *ns;
+
+	if ((flags & (MAILBOX_NONEXISTENT | MAILBOX_NOSELECT)) != 0) {
+		/* doesn't exist, don't even try to get STATUS */
+		return;
+	}
+	if ((flags & MAILBOX_SUBSCRIBED) == 0 &&
+	    (ctx->list_flags & MAILBOX_LIST_ITER_SELECT_SUBSCRIBED) != 0) {
+		/* listing subscriptions, but only child is subscribed */
+		return;
+	}
+
+	/* if we're listing subscriptions and there are subscriptions=no
+	   namespaces, ctx->ns may not point to correct one */
+	ns = mail_namespace_find(ctx->user->namespaces, name);
+	if (imap_status_get(ctx->cmd, ns, name,
+			    &ctx->status_items, &result) < 0) {
+		client_send_line(ctx->cmd->client,
+				 t_strconcat("* ", result.errstr, NULL));
+		return;
+	}
+
+	imap_status_send(ctx->cmd->client, mutf7_name,
+			 &ctx->status_items, &result);
+}
+
+static bool cmd_list_continue(struct client_command_context *cmd)
+{
+        struct cmd_list_context *ctx = cmd->context;
+	const struct mailbox_info *info;
+	enum mailbox_info_flags flags;
+	string_t *str, *mutf7_name;
+	const char *name;
+	int ret = 0;
+
+	if (cmd->cancel) {
+		if (ctx->list_iter != NULL)
+			(void)mailbox_list_iter_deinit(&ctx->list_iter);
+		return TRUE;
+	}
+	str = t_str_new(256);
+	mutf7_name = t_str_new(128);
+	while ((info = mailbox_list_iter_next(ctx->list_iter)) != NULL) {
+		name = info->vname;
+		flags = info->flags;
+
+		if ((flags & MAILBOX_CHILD_SUBSCRIBED) != 0 &&
+		    (flags & MAILBOX_SUBSCRIBED) == 0 &&
+		    ctx->lsub_no_unsubscribed) {
+			/* mask doesn't end with %. we don't want to show
+			   any extra mailboxes. */
+			continue;
+		}
+
+		str_truncate(mutf7_name, 0);
+		if (imap_utf8_to_utf7(name, mutf7_name) < 0)
+			i_panic("LIST: Mailbox name not UTF-8: %s", name);
+
+		str_truncate(str, 0);
+		str_printfa(str, "* %s (", ctx->lsub ? "LSUB" : "LIST");
+		mailbox_flags2str(ctx, str, info->special_use, flags);
+		str_append(str, ") ");
+		list_reply_append_ns_sep_param(str,
+			mail_namespace_get_sep(info->ns));
+		str_append_c(str, ' ');
+		imap_append_astring(str, str_c(mutf7_name));
+		mailbox_childinfo2str(ctx, str, flags);
+
+		ret = client_send_line_next(ctx->cmd->client, str_c(str));
+		if (ctx->used_status) T_BEGIN {
+			list_send_status(ctx, name, str_c(mutf7_name), flags);
+		} T_END;
+		if (ret == 0) {
+			/* buffer is full, continue later */
+			return FALSE;
+		}
+	}
+
+	if (mailbox_list_iter_deinit(&ctx->list_iter) < 0) {
+		client_send_list_error(cmd, ctx->user->namespaces->list);
+		return TRUE;
+	}
+	client_send_tagline(cmd, !ctx->lsub ?
+			    "OK List completed." :
+			    "OK Lsub completed.");
+	return TRUE;
+}
+
+static const char *const *
+list_get_ref_patterns(struct cmd_list_context *ctx, const char *ref,
+		      const char *const *patterns)
+{
+	struct mail_namespace *ns;
+	const char *const *pat, *pattern;
+	ARRAY(const char *) full_patterns;
+
+	if (*ref == '\0')
+		return patterns;
+
+	ns = mail_namespace_find(ctx->user->namespaces, ref);
+
+	t_array_init(&full_patterns, 16);
+	for (pat = patterns; *pat != NULL; pat++) {
+		pattern = mailbox_list_join_refpattern(ns->list, ref, *pat);
+		array_push_back(&full_patterns, &pattern);
+	}
+	array_append_zero(&full_patterns); /* NULL-terminate */
+	return array_front(&full_patterns);
+}
+
+static void cmd_list_init(struct cmd_list_context *ctx,
+			  const char *const *patterns)
+{
+	enum mail_namespace_type type_mask = MAIL_NAMESPACE_TYPE_MASK_ALL;
+
+	ctx->list_iter =
+		mailbox_list_iter_init_namespaces(ctx->user->namespaces,
+						  patterns, type_mask,
+						  ctx->list_flags);
+}
+
+static void cmd_list_ref_root(struct client *client, const char *ref)
+{
+	struct mail_namespace *ns;
+	const char *ns_prefix;
+	char ns_sep;
+	string_t *str;
+
+	/* Special request to return the hierarchy delimiter and mailbox root
+	   name. If namespace has a prefix, it's returned as the mailbox root.
+	   Otherwise we'll emulate UW-IMAP behavior. */
+	ns = mail_namespace_find_visible(client->user->namespaces, ref);
+	if (ns != NULL) {
+		ns_prefix = ns_prefix_mutf7(ns);
+		ns_sep = mail_namespace_get_sep(ns);
+	} else {
+		ns_prefix = "";
+		ns_sep = mail_namespaces_get_root_sep(client->user->namespaces);
+	}
+
+	str = t_str_new(64);
+	str_append(str, "* LIST (\\Noselect) \"");
+	if (ns_sep == '\\' || ns_sep == '"')
+		str_append_c(str, '\\');
+	str_printfa(str, "%c\" ", ns_sep);
+	if (*ns_prefix != '\0') {
+		/* non-hidden namespace, use it as the root name */
+		imap_append_astring(str, ns_prefix);
+	} else {
+		/* Hidden namespace or empty namespace prefix. We could just
+		   return an empty root name, but it's safer to emulate what
+		   UW-IMAP does. With full filesystem access this might even
+		   matter (root of "~user/mail/" is "~user/", not "") */
+		const char *p = strchr(ref, ns_sep);
+
+		if (p == NULL)
+			str_append(str, "\"\"");
+		else
+			imap_append_astring(str, t_strdup_until(ref, p + 1));
+	}
+	client_send_line(client, str_c(str));
+}
+
+bool cmd_list_full(struct client_command_context *cmd, bool lsub)
+{
+	struct client *client = cmd->client;
+	const struct imap_arg *args, *list_args;
+	unsigned int arg_count;
+	struct cmd_list_context *ctx;
+	ARRAY(const char *) patterns = ARRAY_INIT;
+	const char *ref, *pattern, *const *patterns_strarr;
+	string_t *str;
+
+	/* [(<selection options>)] <reference> <pattern>|(<pattern list>)
+	   [RETURN (<return options>)] */
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	ctx = p_new(cmd->pool, struct cmd_list_context, 1);
+	ctx->cmd = cmd;
+	ctx->lsub = lsub;
+	ctx->user = client->user;
+
+	cmd->context = ctx;
+
+	if (!lsub && imap_arg_get_list(&args[0], &list_args)) {
+		/* LIST-EXTENDED selection options */
+		ctx->used_listext = TRUE;
+		if (!parse_select_flags(ctx, list_args))
+			return TRUE;
+		args++;
+	}
+
+	if (!imap_arg_get_astring(&args[0], &ref)) {
+		client_send_command_error(cmd, "Invalid reference.");
+		return TRUE;
+	}
+	str = t_str_new(64);
+	if (imap_utf7_to_utf8(ref, str) == 0)
+		ref = p_strdup(cmd->pool, str_c(str));
+	str_truncate(str, 0);
+
+	if (imap_arg_get_list_full(&args[1], &list_args, &arg_count)) {
+		ctx->used_listext = TRUE;
+		/* convert pattern list to string array */
+		p_array_init(&patterns, cmd->pool, arg_count);
+		for (; !IMAP_ARG_IS_EOL(list_args); list_args++) {
+			if (!imap_arg_get_astring(list_args, &pattern)) {
+				client_send_command_error(cmd,
+					"Invalid pattern list.");
+				return TRUE;
+			}
+			if (imap_utf7_to_utf8(pattern, str) == 0)
+				pattern = p_strdup(cmd->pool, str_c(str));
+			array_push_back(&patterns, &pattern);
+			str_truncate(str, 0);
+		}
+		args += 2;
+	} else {
+		if (!imap_arg_get_astring(&args[1], &pattern)) {
+			client_send_command_error(cmd, "Invalid pattern.");
+			return TRUE;
+		}
+		if (imap_utf7_to_utf8(pattern, str) == 0)
+			pattern = p_strdup(cmd->pool, str_c(str));
+
+		p_array_init(&patterns, cmd->pool, 1);
+		array_push_back(&patterns, &pattern);
+		args += 2;
+
+		if (lsub) {
+			size_t len = strlen(pattern);
+			ctx->lsub_no_unsubscribed = len == 0 ||
+				pattern[len-1] != '%';
+		}
+	}
+
+	if (imap_arg_atom_equals(&args[0], "RETURN") &&
+	    imap_arg_get_list(&args[1], &list_args)) {
+		/* LIST-EXTENDED return options */
+		ctx->used_listext = TRUE;
+		if (!parse_return_flags(ctx, list_args))
+			return TRUE;
+		args += 2;
+	}
+
+	if (lsub) {
+		/* LSUB - we don't care about flags except if
+		   tb-lsub-flags workaround is explicitly set */
+		ctx->list_flags |= MAILBOX_LIST_ITER_SELECT_SUBSCRIBED |
+			MAILBOX_LIST_ITER_SELECT_RECURSIVEMATCH;
+		/* Return SPECIAL-USE flags for LSUB anyway. Outlook 2013
+		   does this and since it's not expensive for us to return
+		   them, it's not worth the trouble of adding an explicit
+		   workaround setting. */
+		ctx->list_flags |= MAILBOX_LIST_ITER_RETURN_SPECIALUSE;
+		if ((cmd->client->set->parsed_workarounds &
+		     WORKAROUND_TB_LSUB_FLAGS) == 0)
+			ctx->list_flags |= MAILBOX_LIST_ITER_RETURN_NO_FLAGS;
+	} else if (!ctx->used_listext) {
+		/* non-extended LIST: use default flags */
+		ctx->list_flags |= MAILBOX_LIST_ITER_RETURN_CHILDREN |
+			MAILBOX_LIST_ITER_RETURN_SPECIALUSE;
+	}
+
+	if (!IMAP_ARG_IS_EOL(args)) {
+		client_send_command_error(cmd, "Extra arguments.");
+		return TRUE;
+	}
+
+	array_append_zero(&patterns); /* NULL-terminate */
+	patterns_strarr = array_front(&patterns);
+	if (!ctx->used_listext && !lsub && *patterns_strarr[0] == '\0') {
+		/* Only LIST ref "" gets us here */
+		cmd_list_ref_root(client, ref);
+		client_send_tagline(cmd, "OK List completed.");
+	} else {
+		patterns_strarr =
+			list_get_ref_patterns(ctx, ref, patterns_strarr);
+		cmd_list_init(ctx, patterns_strarr);
+
+		if (!cmd_list_continue(cmd)) {
+			/* unfinished */
+			cmd->state = CLIENT_COMMAND_STATE_WAIT_OUTPUT;
+			cmd->func = cmd_list_continue;
+			return FALSE;
+		}
+
+		cmd->context = NULL;
+		return TRUE;
+	}
+	return TRUE;
+}
+
+bool cmd_list(struct client_command_context *cmd)
+{
+	return cmd_list_full(cmd, FALSE);
+}
diff --git a/src/imap/cmd-logout.c b/src/imap/cmd-logout.c
new file mode 100644
index 0000000..fbdd416
--- /dev/null
+++ b/src/imap/cmd-logout.c
@@ -0,0 +1,24 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "ostream.h"
+#include "imap-commands.h"
+
+bool cmd_logout(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+
+	client->logged_out = TRUE;
+	client_send_line(client, "* BYE Logging out");
+
+	if (client->mailbox != NULL) {
+		/* this could be done at client_disconnect() as well,
+		   but eg. mbox rewrite takes a while so the waiting is
+		   better to happen before "OK" message. */
+		imap_client_close_mailbox(client);
+	}
+
+	client_send_tagline(cmd, "OK Logout completed.");
+	client_disconnect(client, "Logged out");
+	return TRUE;
+}
diff --git a/src/imap/cmd-lsub.c b/src/imap/cmd-lsub.c
new file mode 100644
index 0000000..55d9b68
--- /dev/null
+++ b/src/imap/cmd-lsub.c
@@ -0,0 +1,9 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+
+bool cmd_lsub(struct client_command_context *cmd)
+{
+	return cmd_list_full(cmd, TRUE);
+}
diff --git a/src/imap/cmd-namespace.c b/src/imap/cmd-namespace.c
new file mode 100644
index 0000000..23d2286
--- /dev/null
+++ b/src/imap/cmd-namespace.c
@@ -0,0 +1,99 @@
+/* Copyright (c) 2003-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "imap-utf7.h"
+#include "imap-quote.h"
+#include "imap-commands.h"
+#include "mail-namespace.h"
+
+struct namespace_order {
+	int secondary_order;
+	struct mail_namespace *ns;
+};
+
+static int namespace_order_cmp(const struct namespace_order *no1,
+			       const struct namespace_order *no2)
+{
+	if (no1->ns->set->order < no2->ns->set->order)
+		return -1;
+	if (no1->ns->set->order > no2->ns->set->order)
+		return 1;
+
+	if (no1->secondary_order < no2->secondary_order)
+		return -1;
+	if (no1->secondary_order > no2->secondary_order)
+		return 1;
+	return 0;
+}
+
+static void list_namespaces(struct mail_namespace *ns,
+			    enum mail_namespace_type type, string_t *str)
+{
+	ARRAY(struct namespace_order) ns_order;
+	struct namespace_order *no;
+	unsigned int count = 0;
+	string_t *mutf7_prefix;
+	char ns_sep;
+
+	t_array_init(&ns_order, 4);
+
+	while (ns != NULL) {
+		if (ns->type == type &&
+		    (ns->flags & NAMESPACE_FLAG_HIDDEN) == 0) {
+			no = array_append_space(&ns_order);
+			no->ns = ns;
+			no->secondary_order = ++count;
+		}
+		ns = ns->next;
+	}
+
+	if (array_count(&ns_order) == 0) {
+		str_append(str, "NIL");
+		return;
+	}
+	array_sort(&ns_order, namespace_order_cmp);
+
+	mutf7_prefix = t_str_new(64);
+	str_append_c(str, '(');
+	array_foreach_modifiable(&ns_order, no) {
+		ns_sep = mail_namespace_get_sep(no->ns);
+		str_append_c(str, '(');
+
+		str_truncate(mutf7_prefix, 0);
+		if (imap_utf8_to_utf7(no->ns->prefix, mutf7_prefix) < 0) {
+			i_panic("LIST: Namespace prefix not UTF-8: %s",
+				no->ns->prefix);
+		}
+
+		imap_append_string(str, str_c(mutf7_prefix));
+		str_append(str, " \"");
+		if (ns_sep == '\\')
+			str_append_c(str, '\\');
+		str_append_c(str, ns_sep);
+		str_append(str, "\")");
+	}
+	str_append_c(str, ')');
+}
+
+bool cmd_namespace(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	string_t *str;
+
+	str = t_str_new(256);
+	str_append(str, "* NAMESPACE ");
+
+	list_namespaces(client->user->namespaces,
+			MAIL_NAMESPACE_TYPE_PRIVATE, str);
+	str_append_c(str, ' ');
+	list_namespaces(client->user->namespaces,
+			MAIL_NAMESPACE_TYPE_SHARED, str);
+	str_append_c(str, ' ');
+	list_namespaces(client->user->namespaces,
+			MAIL_NAMESPACE_TYPE_PUBLIC, str);
+
+	client_send_line(client, str_c(str));
+	client_send_tagline(cmd, "OK Namespace completed.");
+	return TRUE;
+}
diff --git a/src/imap/cmd-noop.c b/src/imap/cmd-noop.c
new file mode 100644
index 0000000..3fd2444
--- /dev/null
+++ b/src/imap/cmd-noop.c
@@ -0,0 +1,15 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-notify.h"
+#include "imap-commands.h"
+
+bool cmd_noop(struct client_command_context *cmd)
+{
+	if (cmd->client->notify_ctx != NULL) {
+		/* flush any delayed notifications now. this is mainly useful
+		   for testing. */
+		imap_notify_flush(cmd->client->notify_ctx);
+	}
+	return cmd_sync(cmd, 0, IMAP_SYNC_FLAG_SAFE, "OK NOOP completed.");
+}
diff --git a/src/imap/cmd-notify.c b/src/imap/cmd-notify.c
new file mode 100644
index 0000000..e043e97
--- /dev/null
+++ b/src/imap/cmd-notify.c
@@ -0,0 +1,597 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "mailbox-list-iter.h"
+#include "imap-quote.h"
+#include "imap-commands.h"
+#include "imap-fetch.h"
+#include "imap-list.h"
+#include "imap-status.h"
+#include "imap-notify.h"
+
+#define IMAP_NOTIFY_MAX_NAMES_PER_NS 100
+
+static const char *imap_notify_event_names[] = {
+	"MessageNew", "MessageExpunge", "FlagChange", "AnnotationChange",
+	"MailboxName", "SubscriptionChange", "MailboxMetadataChange",
+	"ServerMetadataChange"
+};
+
+static int
+cmd_notify_parse_event(const struct imap_arg *arg,
+		       enum imap_notify_event *event_r)
+{
+	const char *str;
+	unsigned int i;
+
+	if (!imap_arg_get_atom(arg, &str))
+		return -1;
+
+	for (i = 0; i < N_ELEMENTS(imap_notify_event_names); i++) {
+		if (strcasecmp(str, imap_notify_event_names[i]) == 0) {
+			*event_r = (enum imap_notify_event)(1 << i);
+			return 0;
+		}
+	}
+	return -1;
+}
+
+static int
+cmd_notify_parse_fetch(struct imap_notify_context *ctx,
+		       const struct imap_arg *list)
+{
+	if (list->type == IMAP_ARG_EOL)
+		return -1; /* at least one attribute must be set */
+	return imap_fetch_att_list_parse(ctx->client, ctx->pool, list,
+					 &ctx->fetch_ctx, &ctx->error);
+}
+
+static int
+cmd_notify_set_selected(struct imap_notify_context *ctx,
+			const struct imap_arg *events)
+{
+#define EV_NEW_OR_EXPUNGE \
+	(IMAP_NOTIFY_EVENT_MESSAGE_NEW | IMAP_NOTIFY_EVENT_MESSAGE_EXPUNGE)
+	const struct imap_arg *list, *fetch_att_list;
+	const char *str;
+	enum imap_notify_event event;
+
+	if (imap_arg_get_atom(events, &str) &&
+	    strcasecmp(str, "NONE") == 0) {
+		/* no events for selected mailbox. this is also the default
+		   when NOTIFY command doesn't specify it explicitly */
+		if (events[1].type != IMAP_ARG_EOL)
+			return -1; /* no extra parameters */
+		return 0;
+	}
+
+	if (!imap_arg_get_list(events, &list))
+		return -1;
+	if (events[1].type != IMAP_ARG_EOL)
+		return -1; /* no extra parameters */
+	if (list->type == IMAP_ARG_EOL)
+		return -1; /* at least one event */
+
+	for (; list->type != IMAP_ARG_EOL; list++) {
+		if (cmd_notify_parse_event(list, &event) < 0)
+			return -1;
+		ctx->selected_events |= event;
+		ctx->global_used_events |= event;
+
+		if (event == IMAP_NOTIFY_EVENT_MESSAGE_NEW &&
+		    imap_arg_get_list(&list[1], &fetch_att_list)) {
+			/* MessageNew: list of fetch-att */
+			if (cmd_notify_parse_fetch(ctx, fetch_att_list) < 0)
+				return -1;
+			list++;
+		}
+	}
+
+	/* if MessageNew or MessageExpunge is specified, both of them must */
+	if ((ctx->selected_events & EV_NEW_OR_EXPUNGE) != 0 &&
+	    (ctx->selected_events & EV_NEW_OR_EXPUNGE) != EV_NEW_OR_EXPUNGE) {
+		ctx->error = "MessageNew and MessageExpunge must be together";
+		return -1;
+	}
+
+	/* if FlagChange or AnnotationChange is specified,
+	   MessageNew and MessageExpunge must also be specified */
+	if ((ctx->selected_events &
+	     (IMAP_NOTIFY_EVENT_FLAG_CHANGE |
+	      IMAP_NOTIFY_EVENT_ANNOTATION_CHANGE)) != 0 &&
+	    (ctx->selected_events & IMAP_NOTIFY_EVENT_MESSAGE_EXPUNGE) == 0) {
+		ctx->error = "FlagChange requires MessageNew and MessageExpunge";
+		return -1;
+	}
+	return 0;
+}
+
+static struct imap_notify_namespace *
+imap_notify_namespace_get(struct imap_notify_context *ctx,
+			  struct mail_namespace *ns)
+{
+	struct imap_notify_namespace *notify_ns;
+
+	array_foreach_modifiable(&ctx->namespaces, notify_ns) {
+		if (notify_ns->ns == ns)
+			return notify_ns;
+	}
+	notify_ns = array_append_space(&ctx->namespaces);
+	notify_ns->ctx = ctx;
+	notify_ns->ns = ns;
+	p_array_init(&notify_ns->mailboxes, ctx->pool, 4);
+	return notify_ns;
+}
+
+static struct imap_notify_mailboxes *
+imap_notify_mailboxes_get(struct imap_notify_namespace *notify_ns,
+			  enum imap_notify_type type,
+			  enum imap_notify_event events)
+{
+	struct imap_notify_mailboxes *notify_boxes;
+
+	array_foreach_modifiable(&notify_ns->mailboxes, notify_boxes) {
+		if (notify_boxes->type == type &&
+		    notify_boxes->events == events)
+			return notify_boxes;
+	}
+	notify_boxes = array_append_space(&notify_ns->mailboxes);
+	notify_boxes->type = type;
+	notify_boxes->events = events;
+	p_array_init(&notify_boxes->names, notify_ns->ctx->pool, 4);
+	return notify_boxes;
+}
+
+static void
+cmd_notify_add_mailbox(struct imap_notify_context *ctx,
+		       struct mail_namespace *ns, const char *name,
+		       enum imap_notify_type type,
+		       enum imap_notify_event events)
+{
+	struct imap_notify_namespace *notify_ns;
+	struct imap_notify_mailboxes *notify_boxes;
+	const char *const *names;
+	unsigned int i, count;
+	size_t cur_len, name_len = strlen(name);
+	char ns_sep = mail_namespace_get_sep(ns);
+
+	if (mail_namespace_is_removable(ns)) {
+		/* exclude removable namespaces */
+		return;
+	}
+
+	if ((ns->flags & NAMESPACE_FLAG_INBOX_USER) != 0 &&
+	    !str_begins(name, "INBOX") &&
+	    strncasecmp(name, "INBOX", 5) == 0 &&
+	    (name[5] == '\0' || name[5] == ns_sep)) {
+		/* we'll do only case-sensitive comparisons later,
+		   so sanitize INBOX to be uppercase */
+		name = t_strconcat("INBOX", name + 5, NULL);
+	}
+
+	notify_ns = imap_notify_namespace_get(ctx, ns);
+	notify_boxes = imap_notify_mailboxes_get(notify_ns, type, events);
+
+	names = array_get(&notify_boxes->names, &count);
+	for (i = 0; i < count; ) {
+		if (strcmp(names[i], name) == 0) {
+			/* exact duplicate, already added */
+			return;
+		}
+		if (type != IMAP_NOTIFY_TYPE_SUBTREE)
+			i++;
+		else {
+			/* see if one is a subtree of the other */
+			cur_len = strlen(names[i]);
+			if (str_begins(name, names[i]) &&
+			    names[i][cur_len] == ns_sep) {
+				/* already matched in this subtree */
+				return;
+			}
+			if (strncmp(names[i], name, name_len) == 0 &&
+			    names[i][name_len] == ns_sep) {
+				/* we're adding a parent, remove the child */
+				array_delete(&notify_boxes->names, i, 1);
+				names = array_get(&notify_boxes->names, &count);
+			} else {
+				i++;
+			}
+		}
+	}
+	name = p_strdup(ctx->pool, name);
+	array_push_back(&notify_boxes->names, &name);
+
+	ctx->global_max_mailbox_names =
+		I_MAX(ctx->global_max_mailbox_names,
+		      array_count(&notify_boxes->names));
+}
+
+static void cmd_notify_add_personal(struct imap_notify_context *ctx,
+				    enum imap_notify_event events)
+{
+	struct mail_namespace *ns;
+
+	for (ns = ctx->client->user->namespaces; ns != NULL; ns = ns->next) {
+		if (ns->type == MAIL_NAMESPACE_TYPE_PRIVATE) {
+			cmd_notify_add_mailbox(ctx, ns, "",
+				IMAP_NOTIFY_TYPE_SUBTREE, events);
+		}
+	}
+}
+
+static int
+imap_notify_refresh_subscriptions(struct client_command_context *cmd,
+				  struct imap_notify_context *ctx)
+{
+	struct mailbox_list_iterate_context *iter;
+	struct mail_namespace *ns;
+
+	if (!ctx->have_subscriptions)
+		return 0;
+
+	/* make sure subscriptions are refreshed at least once */
+	for (ns = ctx->client->user->namespaces; ns != NULL; ns = ns->next) {
+		iter = mailbox_list_iter_init(ns->list, "*", MAILBOX_LIST_ITER_SELECT_SUBSCRIBED);
+		(void)mailbox_list_iter_next(iter);
+		if (mailbox_list_iter_deinit(&iter) < 0) {
+			client_send_list_error(cmd, ns->list);
+			return -1;
+		}
+	}
+	return 0;
+}
+
+static void cmd_notify_add_subscribed(struct imap_notify_context *ctx,
+				      enum imap_notify_event events)
+{
+	struct mail_namespace *ns;
+
+	ctx->have_subscriptions = TRUE;
+	for (ns = ctx->client->user->namespaces; ns != NULL; ns = ns->next) {
+		cmd_notify_add_mailbox(ctx, ns, "",
+				       IMAP_NOTIFY_TYPE_SUBSCRIBED, events);
+	}
+}
+
+static void
+cmd_notify_add_mailbox_namespaces(struct imap_notify_context *ctx,
+				  const char *name,
+				  enum imap_notify_type type,
+				  enum imap_notify_event events)
+{
+	struct mail_namespace *ns;
+
+	ns = mail_namespace_find(ctx->client->user->namespaces, name);
+	cmd_notify_add_mailbox(ctx, ns, name, type, events);
+}
+
+static int
+cmd_notify_add_mailboxes(struct imap_notify_context *ctx,
+			 const struct imap_arg *arg,
+			 enum imap_notify_type type,
+			 enum imap_notify_event events)
+{
+	const struct imap_arg *list;
+	const char *name;
+
+	if (imap_arg_get_astring(arg, &name)) {
+		cmd_notify_add_mailbox_namespaces(ctx, name, type, events);
+		return 0;
+	}
+	if (!imap_arg_get_list(arg, &list))
+		return -1;
+
+	for (; list->type != IMAP_ARG_EOL; list++) {
+		if (!imap_arg_get_astring(list, &name))
+			return -1;
+
+		cmd_notify_add_mailbox_namespaces(ctx, name, type, events);
+	}
+	return 0;
+}
+
+static int
+cmd_notify_set(struct imap_notify_context *ctx, const struct imap_arg *args)
+{
+	const struct imap_arg *event_group, *mailboxes, *list;
+	const char *str, *filter_mailboxes;
+	enum imap_notify_event event, event_mask;
+
+	if (imap_arg_get_atom(args, &str) &&
+	    strcasecmp(str, "STATUS") == 0) {
+		/* send STATUS replies for all matched mailboxes before
+		   NOTIFY's OK reply */
+		ctx->send_immediate_status = TRUE;
+		args++;
+	}
+	for (; args->type != IMAP_ARG_EOL; args++) {
+		if (!imap_arg_get_list(args, &event_group))
+			return -1;
+
+		/* filter-mailboxes */
+		if (!imap_arg_get_atom(event_group, &filter_mailboxes))
+			return -1;
+		event_group++;
+
+		if (strcasecmp(filter_mailboxes, "selected") == 0 ||
+		    strcasecmp(filter_mailboxes, "selected-delayed") == 0) {
+			/* setting events for selected mailbox.
+			   handle specially. */
+			if (ctx->selected_set) {
+				ctx->error = "Duplicate selected filter";
+				return -1;
+			}
+			ctx->selected_set = TRUE;
+			if (strcasecmp(filter_mailboxes, "selected") == 0)
+				ctx->selected_immediate_expunges = TRUE;
+			if (cmd_notify_set_selected(ctx, event_group) < 0)
+				return -1;
+			continue;
+		}
+
+		if (strcasecmp(filter_mailboxes, "subtree") == 0 ||
+		    strcasecmp(filter_mailboxes, "mailboxes") == 0) {
+			if (event_group->type == IMAP_ARG_EOL)
+				return -1;
+			mailboxes = event_group++;
+			/* check that the mailboxes parameter is valid */
+			if (IMAP_ARG_IS_ASTRING(mailboxes))
+				;
+			else if (!imap_arg_get_list(mailboxes, &list))
+				return -1;
+			else if (list->type == IMAP_ARG_EOL) {
+				/* should have at least one mailbox */
+				return -1;
+			}
+		} else {
+			mailboxes = NULL;
+		}
+
+		/* parse events */
+		if (imap_arg_get_atom(event_group, &str) &&
+		    strcasecmp(str, "NONE") == 0) {
+			/* NONE is the default, ignore this */
+			continue;
+		}
+		if (!imap_arg_get_list(event_group, &list) ||
+		    list[0].type == IMAP_ARG_EOL)
+			return -1;
+
+		event_mask = 0;
+		for (; list->type != IMAP_ARG_EOL; list++) {
+			if (cmd_notify_parse_event(list, &event) < 0)
+				return -1;
+			event_mask |= event;
+			ctx->global_used_events |= event;
+		}
+
+		/* we can't currently know inboxes, so treat it the
+		   same as personal */
+		if (strcasecmp(filter_mailboxes, "inboxes") == 0 ||
+		    strcasecmp(filter_mailboxes, "personal") == 0)
+			cmd_notify_add_personal(ctx, event_mask);
+		else if (strcasecmp(filter_mailboxes, "subscribed") == 0)
+			cmd_notify_add_subscribed(ctx, event_mask);
+		else if (strcasecmp(filter_mailboxes, "subtree") == 0) {
+			if (cmd_notify_add_mailboxes(ctx, mailboxes,
+						     IMAP_NOTIFY_TYPE_SUBTREE,
+						     event_mask) < 0)
+				return -1;
+		} else if (strcasecmp(filter_mailboxes, "mailboxes") == 0) {
+			if (cmd_notify_add_mailboxes(ctx, mailboxes,
+						     IMAP_NOTIFY_TYPE_MAILBOX,
+						     event_mask) < 0)
+				return -1;
+		} else {
+			return -1;
+		}
+	}
+	return 0;
+}
+
+static void
+imap_notify_box_list_noperm(struct client *client, struct mailbox *box)
+{
+	string_t *str = t_str_new(128);
+	char ns_sep = mail_namespace_get_sep(mailbox_get_namespace(box));
+	enum mailbox_info_flags mailbox_flags;
+
+	if (mailbox_list_mailbox(mailbox_get_namespace(box)->list,
+				 mailbox_get_name(box), &mailbox_flags) < 0)
+		mailbox_flags = 0;
+
+	str_append(str, "* LIST (");
+	if (imap_mailbox_flags2str(str, mailbox_flags))
+		str_append_c(str, ' ');
+	str_append(str, "\\NoAccess) \"");
+	if (ns_sep == '\\')
+		str_append_c(str, '\\');
+	str_append_c(str, ns_sep);
+	str_append(str, "\" ");
+
+	imap_append_astring(str, mailbox_get_vname(box));
+	client_send_line(client, str_c(str));
+}
+
+static void
+imap_notify_box_send_status(struct client_command_context *cmd,
+			    struct imap_notify_context *ctx,
+			    const struct mailbox_info *info)
+{
+	struct mailbox *box;
+	struct imap_status_items items;
+	struct imap_status_result result;
+
+	if ((info->flags & (MAILBOX_NONEXISTENT | MAILBOX_NOSELECT)) != 0)
+		return;
+
+	/* don't send STATUS to selected mailbox */
+	if (cmd->client->mailbox != NULL &&
+	    mailbox_equals(cmd->client->mailbox, info->ns, info->vname))
+		return;
+
+	i_zero(&items);
+	i_zero(&result);
+
+	items.flags = IMAP_STATUS_ITEM_UIDVALIDITY | IMAP_STATUS_ITEM_UIDNEXT |
+		IMAP_STATUS_ITEM_MESSAGES | IMAP_STATUS_ITEM_UNSEEN;
+	if ((ctx->global_used_events & (IMAP_NOTIFY_EVENT_FLAG_CHANGE |
+					IMAP_NOTIFY_EVENT_ANNOTATION_CHANGE)) != 0)
+		items.flags |= IMAP_STATUS_ITEM_HIGHESTMODSEQ;
+
+	box = mailbox_alloc(info->ns->list, info->vname, MAILBOX_FLAG_READONLY);
+	(void)mailbox_enable(box, client_enabled_mailbox_features(ctx->client));
+
+	if (imap_status_get(cmd, info->ns, info->vname, &items, &result) < 0) {
+		if (result.error == MAIL_ERROR_PERM)
+			imap_notify_box_list_noperm(ctx->client, box);
+		else if (result.error != MAIL_ERROR_NOTFOUND) {
+			client_send_line(ctx->client,
+				t_strconcat("* ", result.errstr, NULL));
+		}
+	} else {
+		imap_status_send(ctx->client, info->vname, &items, &result);
+	}
+	mailbox_free(&box);
+}
+
+static bool imap_notify_ns_want_status(struct imap_notify_namespace *notify_ns)
+{
+	const struct imap_notify_mailboxes *notify_boxes;
+
+	array_foreach(&notify_ns->mailboxes, notify_boxes) {
+		if ((notify_boxes->events &
+		     (IMAP_NOTIFY_EVENT_MESSAGE_NEW |
+		      IMAP_NOTIFY_EVENT_MESSAGE_EXPUNGE |
+		      IMAP_NOTIFY_EVENT_ANNOTATION_CHANGE |
+		      IMAP_NOTIFY_EVENT_FLAG_CHANGE)) != 0)
+			return TRUE;
+	}
+	return FALSE;
+}
+
+static void
+imap_notify_ns_send_status(struct client_command_context *cmd,
+			   struct imap_notify_context *ctx,
+			   struct imap_notify_namespace *notify_ns)
+{
+	struct mailbox_list_iterate_context *iter;
+	const struct imap_notify_mailboxes *notify_boxes;
+	const struct mailbox_info *info;
+
+	if (!imap_notify_ns_want_status(notify_ns))
+		return;
+
+	/* set _RETURN_SUBSCRIBED flag just in case IMAP_NOTIFY_TYPE_SUBSCRIBED
+	   is used, which requires refreshing subscriptions */
+	iter = mailbox_list_iter_init(notify_ns->ns->list, "*",
+				      MAILBOX_LIST_ITER_RETURN_SUBSCRIBED |
+				      MAILBOX_LIST_ITER_RETURN_NO_FLAGS);
+	while ((info = mailbox_list_iter_next(iter)) != NULL) {
+		array_foreach(&notify_ns->mailboxes, notify_boxes) {
+			if (imap_notify_match_mailbox(notify_ns, notify_boxes,
+						      info->vname)) {
+				imap_notify_box_send_status(cmd, ctx, info);
+				break;
+			}
+		}
+	}
+	if (mailbox_list_iter_deinit(&iter) < 0) {
+		client_send_line(notify_ns->ctx->client,
+				 "* NO Mailbox listing failed");
+	}
+}
+
+static void cmd_notify_send_status(struct client_command_context *cmd,
+				   struct imap_notify_context *ctx)
+{
+	struct imap_notify_namespace *notify_ns;
+
+	array_foreach_modifiable(&ctx->namespaces, notify_ns)
+		imap_notify_ns_send_status(cmd, ctx, notify_ns);
+}
+
+bool cmd_notify(struct client_command_context *cmd)
+{
+	struct imap_notify_context *ctx;
+	const struct imap_arg *args;
+	const char *str;
+	int ret = 0;
+	pool_t pool;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	pool = pool_alloconly_create("imap notify context", 1024);
+	ctx = p_new(pool, struct imap_notify_context, 1);
+	ctx->pool = pool;
+	ctx->client = cmd->client;
+	p_array_init(&ctx->namespaces, pool, 4);
+
+	if (!imap_arg_get_atom(&args[0], &str))
+		ret = -1;
+	else if (strcasecmp(str, "NONE") == 0)
+		;
+	else if (strcasecmp(str, "SET") == 0)
+		ret = cmd_notify_set(ctx, args+1);
+	else
+		ret = -1;
+
+	if (ret < 0) {
+		client_send_command_error(cmd, ctx->error != NULL ? ctx->error :
+					  "Invalid arguments.");
+		pool_unref(&pool);
+		return TRUE;
+	}
+
+	if ((ctx->global_used_events & UNSUPPORTED_EVENTS) != 0) {
+		string_t *client_error = t_str_new(128);
+		unsigned int i;
+
+		str_append(client_error, "NO [BADEVENT");
+		for (i = 0; i < N_ELEMENTS(imap_notify_event_names); i++) {
+			if ((ctx->global_used_events & (1 << i)) != 0 &&
+			    ((1 << i) & UNSUPPORTED_EVENTS) != 0) {
+				str_append_c(client_error, ' ');
+				str_append(client_error, imap_notify_event_names[i]);
+			}
+		}
+		str_append(client_error, "] Unsupported NOTIFY events.");
+		client_send_tagline(cmd, str_c(client_error));
+		pool_unref(&pool);
+		return TRUE;
+	}
+
+	if (array_count(&ctx->namespaces) == 0) {
+		/* selected mailbox only */
+	} else if (ctx->global_max_mailbox_names > IMAP_NOTIFY_MAX_NAMES_PER_NS) {
+		client_send_tagline(cmd,
+			"NO [NOTIFICATIONOVERFLOW] Too many mailbox names");
+		pool_unref(&pool);
+		return TRUE;
+	} else if (imap_notify_refresh_subscriptions(cmd, ctx) < 0) {
+		/* tagline already sent */
+		pool_unref(&pool);
+		return TRUE;
+	} else if (imap_notify_begin(ctx) < 0) {
+		client_send_tagline(cmd,
+			"NO [NOTIFICATIONOVERFLOW] NOTIFY not supported for these mailboxes.");
+		pool_unref(&pool);
+		return TRUE;
+	}
+	if (cmd->client->notify_ctx != NULL)
+		imap_notify_deinit(&cmd->client->notify_ctx);
+
+	if (ctx->send_immediate_status)
+		cmd_notify_send_status(cmd, ctx);
+	cmd->client->notify_immediate_expunges =
+		ctx->selected_immediate_expunges;
+	cmd->client->notify_count_changes =
+		(ctx->selected_events & IMAP_NOTIFY_EVENT_MESSAGE_NEW) != 0;
+	cmd->client->notify_flag_changes =
+		(ctx->selected_events & IMAP_NOTIFY_EVENT_FLAG_CHANGE) != 0;
+
+	cmd->client->notify_ctx = ctx;
+	return cmd_sync(cmd, 0, IMAP_SYNC_FLAG_SAFE, "OK NOTIFY completed.");
+}
diff --git a/src/imap/cmd-rename.c b/src/imap/cmd-rename.c
new file mode 100644
index 0000000..45b44fd
--- /dev/null
+++ b/src/imap/cmd-rename.c
@@ -0,0 +1,51 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "mail-namespace.h"
+#include "imap-commands.h"
+
+bool cmd_rename(struct client_command_context *cmd)
+{
+	struct mail_namespace *old_ns, *new_ns;
+	struct mailbox *old_box, *new_box;
+	const char *oldname, *newname;
+	size_t oldlen;
+
+	/* <old name> <new name> */
+	if (!client_read_string_args(cmd, 2, &oldname, &newname))
+		return FALSE;
+
+	old_ns = client_find_namespace(cmd, &oldname);
+	if (old_ns == NULL)
+		return TRUE;
+	new_ns = client_find_namespace(cmd, &newname);
+	if (new_ns == NULL)
+		return TRUE;
+
+	if (old_ns == new_ns) {
+		/* disallow box -> box/child, because it may break clients and
+		   there's really no point in doing it anyway. */
+		old_ns = mailbox_list_get_namespace(old_ns->list);
+		oldlen = strlen(oldname);
+		if (str_begins(newname, oldname) &&
+		    newname[oldlen] == mail_namespace_get_sep(old_ns)) {
+			client_send_tagline(cmd,
+				"NO Can't rename mailbox under its own child.");
+			return TRUE;
+		}
+	}
+
+	old_box = mailbox_alloc(old_ns->list, oldname, 0);
+	new_box = mailbox_alloc(new_ns->list, newname, 0);
+	event_add_str(cmd->global_event, "old_mailbox",
+		      mailbox_get_vname(old_box));
+	event_add_str(cmd->global_event, "new_mailbox",
+		      mailbox_get_vname(new_box));
+	if (mailbox_rename(old_box, new_box) < 0)
+		client_send_box_error(cmd, old_box);
+	else
+		client_send_tagline(cmd, "OK Rename completed.");
+	mailbox_free(&old_box);
+	mailbox_free(&new_box);
+	return TRUE;
+}
diff --git a/src/imap/cmd-resetkey.c b/src/imap/cmd-resetkey.c
new file mode 100644
index 0000000..3475994
--- /dev/null
+++ b/src/imap/cmd-resetkey.c
@@ -0,0 +1,97 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-resp-code.h"
+#include "imap-commands.h"
+#include "imap-urlauth.h"
+
+static bool cmd_resetkey_all(struct client_command_context *cmd)
+{
+	if (imap_urlauth_reset_all_keys(cmd->client->urlauth_ctx) < 0) {
+		client_send_internal_error(cmd);
+		return TRUE;
+	}
+
+	client_send_tagline(cmd, "OK All keys removed.");
+	return TRUE;
+}
+
+static bool
+cmd_resetkey_mailbox(struct client_command_context *cmd,
+		     const char *mailbox, const struct imap_arg *mech_args)
+{
+	struct mail_namespace *ns;
+	enum mailbox_flags flags = MAILBOX_FLAG_READONLY;
+	struct mailbox *box;
+
+	/* check mechanism arguments (we support only INTERNAL mechanism) */
+	while (!IMAP_ARG_IS_EOL(mech_args)) {
+		const char *mechanism;
+
+		if (imap_arg_get_astring(mech_args, &mechanism)) {
+			if (strcasecmp(mechanism, "INTERNAL") != 0) {
+				client_send_tagline(cmd,
+					"NO Unsupported URLAUTH mechanism.");
+				return TRUE;
+			}
+		} else {
+			client_send_command_error(cmd, "Invalid arguments.");
+			return TRUE;
+		}
+
+		mech_args++;
+	}
+
+	/* find mailbox namespace */
+	ns = client_find_namespace(cmd, &mailbox);
+	if (ns == NULL)
+		return TRUE;
+
+	/* open mailbox */
+	box = mailbox_alloc(ns->list, mailbox, flags);
+	event_add_str(cmd->global_event, "mailbox", mailbox_get_vname(box));
+	if (mailbox_open(box) < 0) {
+		client_send_box_error(cmd, box);
+		mailbox_free(&box);
+		return TRUE;
+	}
+
+	/* check urlauth environment and reset requested key */
+	if (imap_urlauth_reset_mailbox_key(cmd->client->urlauth_ctx, box) < 0) {
+		client_send_internal_error(cmd);
+		mailbox_free(&box);
+		return TRUE;
+	}
+
+	/* confirm success */
+	/* FIXME: RFC Says: `Any current IMAP session logged in as the user
+	   that has the mailbox selected will receive an untagged OK response
+	   with the URLMECH status response code'. We currently don't do that
+	   at all. We could probably do it by communicating via mailbox list
+	   index. */
+	client_send_tagline(cmd, "OK [URLMECH INTERNAL] Key removed.");
+	mailbox_free(&box);
+	return TRUE;
+}
+
+bool cmd_resetkey(struct client_command_context *cmd)
+{
+	const struct imap_arg *args;
+	const char *mailbox;
+
+	if (cmd->client->urlauth_ctx == NULL) {
+		client_send_command_error(cmd, "URLAUTH disabled.");
+		return TRUE;
+	}
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (IMAP_ARG_IS_EOL(&args[0]))
+		return cmd_resetkey_all(cmd);
+	else if (imap_arg_get_astring(&args[0], &mailbox))
+		return cmd_resetkey_mailbox(cmd, mailbox, &args[1]);
+
+	client_send_command_error(cmd, "Invalid arguments.");
+	return TRUE;
+}
diff --git a/src/imap/cmd-search.c b/src/imap/cmd-search.c
new file mode 100644
index 0000000..52be6f6
--- /dev/null
+++ b/src/imap/cmd-search.c
@@ -0,0 +1,49 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-search-args.h"
+#include "imap-search.h"
+
+bool cmd_search(struct client_command_context *cmd)
+{
+	struct imap_search_context *ctx;
+	struct mail_search_args *sargs;
+	const struct imap_arg *args;
+	const char *charset;
+	int ret;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	ctx = p_new(cmd->pool, struct imap_search_context, 1);
+	ctx->cmd = cmd;
+
+	if ((ret = cmd_search_parse_return_if_found(ctx, &args)) <= 0) {
+		/* error / waiting for unambiguity */
+		return ret < 0;
+	}
+
+	if (imap_arg_atom_equals(args, "CHARSET")) {
+		/* CHARSET specified */
+		if (!imap_arg_get_astring(&args[1], &charset)) {
+			client_send_command_error(cmd,
+				"Invalid charset argument.");
+			imap_search_context_free(ctx);
+			return TRUE;
+		}
+		args += 2;
+	} else {
+		charset = "UTF-8";
+	}
+
+	ret = imap_search_args_build(cmd, args, charset, &sargs);
+	if (ret <= 0) {
+		imap_search_context_free(ctx);
+		return ret < 0;
+	}
+
+	return imap_search_start(ctx, sargs, NULL);
+}
diff --git a/src/imap/cmd-select.c b/src/imap/cmd-select.c
new file mode 100644
index 0000000..c9af870
--- /dev/null
+++ b/src/imap/cmd-select.c
@@ -0,0 +1,426 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "seq-range-array.h"
+#include "time-util.h"
+#include "imap-commands.h"
+#include "mail-search-build.h"
+#include "imap-search-args.h"
+#include "imap-seqset.h"
+#include "imap-fetch.h"
+#include "imap-sync.h"
+
+
+struct imap_select_context {
+	struct client_command_context *cmd;
+	struct mail_namespace *ns;
+	struct mailbox *box;
+
+	struct imap_fetch_context *fetch_ctx;
+
+	uint32_t qresync_uid_validity;
+	uint64_t qresync_modseq;
+	ARRAY_TYPE(seq_range) qresync_known_uids;
+	ARRAY_TYPE(uint32_t) qresync_sample_seqset;
+	ARRAY_TYPE(uint32_t) qresync_sample_uidset;
+
+	bool condstore:1;
+};
+
+static int select_qresync_get_uids(struct imap_select_context *ctx,
+				   const ARRAY_TYPE(seq_range) *seqset,
+				   const ARRAY_TYPE(seq_range) *uidset)
+{
+	const struct seq_range *uid_range;
+	struct seq_range_iter seq_iter;
+	unsigned int i, uid_count, diff, n = 0;
+	uint32_t seq;
+
+	/* change all n:m ranges to n,m and store the results */
+	uid_range = array_get(uidset, &uid_count);
+
+	seq_range_array_iter_init(&seq_iter, seqset);
+	i_array_init(&ctx->qresync_sample_uidset, uid_count);
+	i_array_init(&ctx->qresync_sample_seqset, uid_count);
+	for (i = 0; i < uid_count; i++) {
+		if (!seq_range_array_iter_nth(&seq_iter, n++, &seq))
+			return -1;
+		array_push_back(&ctx->qresync_sample_uidset,
+				&uid_range[i].seq1);
+		array_push_back(&ctx->qresync_sample_seqset, &seq);
+
+		diff = uid_range[i].seq2 - uid_range[i].seq1;
+		if (diff > 0) {
+			n += diff - 1;
+			if (!seq_range_array_iter_nth(&seq_iter, n++, &seq))
+				return -1;
+
+			array_push_back(&ctx->qresync_sample_uidset,
+					&uid_range[i].seq2);
+			array_push_back(&ctx->qresync_sample_seqset, &seq);
+		}
+	}
+	if (seq_range_array_iter_nth(&seq_iter, n, &seq))
+		return -1;
+	return 0;
+}
+
+static bool
+select_parse_qresync_known_set(struct imap_select_context *ctx,
+			       const struct imap_arg *args,
+			       const char **error_r)
+{
+	ARRAY_TYPE(seq_range) seqset, uidset;
+	const char *str;
+
+	t_array_init(&seqset, 32);
+	if (!imap_arg_get_atom(args, &str) ||
+	    imap_seq_set_nostar_parse(str, &seqset) < 0) {
+		*error_r = "Invalid QRESYNC known-sequence-set";
+		return FALSE;
+	}
+	args++;
+
+	t_array_init(&uidset, 32);
+	if (!imap_arg_get_atom(args, &str) ||
+	    imap_seq_set_nostar_parse(str, &uidset) < 0) {
+		*error_r = "Invalid QRESYNC known-uid-set";
+		return FALSE;
+	}
+	args++;
+
+	if (select_qresync_get_uids(ctx, &seqset, &uidset) < 0) {
+		*error_r = "Invalid QRESYNC sets";
+		return FALSE;
+	}
+	if (!IMAP_ARG_IS_EOL(args)) {
+		*error_r = "Too many parameters to QRESYNC known set";
+		return FALSE;
+	}
+	return TRUE;
+}
+
+static bool
+select_parse_qresync(struct imap_select_context *ctx,
+		     const struct imap_arg *args, const char **error_r)
+{
+	const struct imap_arg *list_args;
+	const char *str;
+	unsigned int count;
+
+	if (!client_has_enabled(ctx->cmd->client, imap_feature_qresync)) {
+		*error_r = "QRESYNC not enabled";
+		return FALSE;
+	}
+	if (!imap_arg_get_list_full(args, &args, &count)) {
+		*error_r = "QRESYNC parameters missing";
+		return FALSE;
+	}
+
+	if (!imap_arg_get_atom(&args[0], &str) ||
+	    str_to_uint32(str, &ctx->qresync_uid_validity) < 0 ||
+	    !imap_arg_get_atom(&args[1], &str) ||
+	    str_to_uint64(str, &ctx->qresync_modseq) < 0) {
+		*error_r = "Invalid QRESYNC parameters";
+		return FALSE;
+	}
+	args += 2;
+
+	i_array_init(&ctx->qresync_known_uids, 64);
+	if (imap_arg_get_atom(args, &str)) {
+		if (imap_seq_set_nostar_parse(str, &ctx->qresync_known_uids) < 0) {
+			*error_r = "Invalid QRESYNC known-uids";
+			return FALSE;
+		}
+		args++;
+	} else {
+		seq_range_array_add_range(&ctx->qresync_known_uids,
+					  1, (uint32_t)-1);
+	}
+	if (imap_arg_get_list(args, &list_args)) {
+		if (!select_parse_qresync_known_set(ctx, list_args, error_r))
+			return FALSE;
+		args++;
+	}
+	if (!IMAP_ARG_IS_EOL(args)) {
+		*error_r = "Invalid QRESYNC parameters";
+		return FALSE;
+	}
+	return TRUE;
+}
+
+static bool
+select_parse_options(struct imap_select_context *ctx,
+		     const struct imap_arg *args, const char **error_r)
+{
+	const char *name;
+
+	while (!IMAP_ARG_IS_EOL(args)) {
+		if (!imap_arg_get_atom(args, &name)) {
+			*error_r = "SELECT options contain non-atoms.";
+			return FALSE;
+		}
+		name = t_str_ucase(name);
+		args++;
+
+		if (strcmp(name, "CONDSTORE") == 0)
+			ctx->condstore = TRUE;
+		else if (strcmp(name, "QRESYNC") == 0) {
+			if (!select_parse_qresync(ctx, args, error_r))
+				return FALSE;
+			args++;
+		} else {
+			*error_r = "Unknown FETCH modifier";
+			return FALSE;
+		}
+	}
+	return TRUE;
+}
+
+static void select_context_free(struct imap_select_context *ctx)
+{
+	if (array_is_created(&ctx->qresync_known_uids))
+		array_free(&ctx->qresync_known_uids);
+	if (array_is_created(&ctx->qresync_sample_seqset))
+		array_free(&ctx->qresync_sample_seqset);
+	if (array_is_created(&ctx->qresync_sample_uidset))
+		array_free(&ctx->qresync_sample_uidset);
+}
+
+static void cmd_select_finish(struct imap_select_context *ctx, int ret)
+{
+	const char *resp_code;
+
+	if (ret < 0) {
+		if (ctx->box != NULL)
+			mailbox_free(&ctx->box);
+		ctx->cmd->client->mailbox = NULL;
+	} else {
+		resp_code = mailbox_is_readonly(ctx->box) ?
+			"READ-ONLY" : "READ-WRITE";
+		client_send_tagline(ctx->cmd, t_strdup_printf(
+			"OK [%s] %s completed", resp_code,
+			ctx->cmd->client->mailbox_examined ? "Examine" : "Select"));
+	}
+	select_context_free(ctx);
+}
+
+static bool cmd_select_continue(struct client_command_context *cmd)
+{
+        struct imap_select_context *ctx = cmd->context;
+	int ret;
+
+	if (imap_fetch_more(ctx->fetch_ctx, cmd) == 0) {
+		/* unfinished */
+		return FALSE;
+	}
+
+	ret = imap_fetch_end(ctx->fetch_ctx);
+	if (ret < 0)
+		client_send_box_error(ctx->cmd, ctx->box);
+	imap_fetch_free(&ctx->fetch_ctx);
+	cmd_select_finish(ctx, ret);
+	return TRUE;
+}
+
+static int select_qresync(struct imap_select_context *ctx)
+{
+	struct imap_fetch_context *fetch_ctx;
+	struct mail_search_args *search_args;
+	struct imap_fetch_qresync_args qresync_args;
+	int ret;
+
+	search_args = mail_search_build_init();
+	search_args->args = p_new(search_args->pool, struct mail_search_arg, 1);
+	search_args->args->type = SEARCH_UIDSET;
+	search_args->args->value.seqset = ctx->qresync_known_uids;
+	imap_search_add_changed_since(search_args, ctx->qresync_modseq);
+
+	i_zero(&qresync_args);
+	qresync_args.qresync_sample_seqset = &ctx->qresync_sample_seqset;
+	qresync_args.qresync_sample_uidset = &ctx->qresync_sample_uidset;
+
+	if (imap_fetch_send_vanished(ctx->cmd->client, ctx->box,
+				     search_args, &qresync_args) < 0) {
+		mail_search_args_unref(&search_args);
+		return -1;
+	}
+
+	fetch_ctx = imap_fetch_alloc(ctx->cmd->client, ctx->cmd->pool,
+		t_strdup_printf("%s %s", ctx->cmd->name, ctx->cmd->args));
+
+	imap_fetch_init_nofail_handler(fetch_ctx, imap_fetch_uid_init);
+	imap_fetch_init_nofail_handler(fetch_ctx, imap_fetch_flags_init);
+	imap_fetch_init_nofail_handler(fetch_ctx, imap_fetch_modseq_init);
+
+	imap_fetch_begin(fetch_ctx, ctx->box, search_args);
+	mail_search_args_unref(&search_args);
+
+	if (imap_fetch_more(fetch_ctx, ctx->cmd) == 0) {
+		/* unfinished */
+		ctx->fetch_ctx = fetch_ctx;
+		ctx->cmd->state = CLIENT_COMMAND_STATE_WAIT_OUTPUT;
+
+		ctx->cmd->func = cmd_select_continue;
+		ctx->cmd->context = ctx;
+		return 0;
+	}
+	ret = imap_fetch_end(fetch_ctx);
+	imap_fetch_free(&fetch_ctx);
+	return ret < 0 ? -1 : 1;
+}
+
+static int
+select_open(struct imap_select_context *ctx, const char *mailbox, bool readonly)
+{
+	struct client *client = ctx->cmd->client;
+	struct mailbox_status status;
+	enum mailbox_flags flags = 0;
+	int ret = 0;
+
+	if (readonly)
+		flags |= MAILBOX_FLAG_READONLY;
+	else
+		flags |= MAILBOX_FLAG_DROP_RECENT;
+	ctx->box = mailbox_alloc(ctx->ns->list, mailbox, flags);
+	event_add_str(ctx->cmd->global_event, "mailbox",
+		      mailbox_get_vname(ctx->box));
+	if (mailbox_open(ctx->box) < 0) {
+		client_send_box_error(ctx->cmd, ctx->box);
+		mailbox_free(&ctx->box);
+		return -1;
+	}
+
+	ret = mailbox_enable(ctx->box, client_enabled_mailbox_features(client));
+	if (ret < 0 ||
+	    mailbox_sync(ctx->box, MAILBOX_SYNC_FLAG_FULL_READ) < 0) {
+		client_send_box_error(ctx->cmd, ctx->box);
+		return -1;
+	}
+	mailbox_get_open_status(ctx->box, STATUS_MESSAGES | STATUS_RECENT |
+				STATUS_FIRST_UNSEEN_SEQ | STATUS_UIDVALIDITY |
+				STATUS_UIDNEXT | STATUS_KEYWORDS |
+				STATUS_HIGHESTMODSEQ, &status);
+
+	client->mailbox = ctx->box;
+	client->mailbox_examined = readonly;
+	client->messages_count = status.messages;
+	client->recent_count = status.recent;
+	client->uidvalidity = status.uidvalidity;
+	client->notify_uidnext = status.uidnext;
+
+	client_update_mailbox_flags(client, status.keywords);
+	client_send_mailbox_flags(client, TRUE);
+
+	client_send_line(client,
+		t_strdup_printf("* %u EXISTS", status.messages));
+	client_send_line(client,
+		t_strdup_printf("* %u RECENT", status.recent));
+
+	if (status.first_unseen_seq != 0) {
+		client_send_line(client,
+			t_strdup_printf("* OK [UNSEEN %u] First unseen.",
+					status.first_unseen_seq));
+	}
+
+	client_send_line(client,
+			 t_strdup_printf("* OK [UIDVALIDITY %u] UIDs valid",
+					 status.uidvalidity));
+
+	client_send_line(client,
+			 t_strdup_printf("* OK [UIDNEXT %u] Predicted next UID",
+					 status.uidnext));
+
+	client->nonpermanent_modseqs = status.nonpermanent_modseqs;
+	if (status.nonpermanent_modseqs) {
+		client_send_line(client,
+				 "* OK [NOMODSEQ] No permanent modsequences");
+	} else if (!status.no_modseq_tracking) {
+		client_send_line(client,
+			t_strdup_printf("* OK [HIGHESTMODSEQ %"PRIu64"] Highest",
+					status.highest_modseq));
+		client->sync_last_full_modseq = status.highest_modseq;
+	}
+
+	if (ctx->qresync_uid_validity == status.uidvalidity &&
+	    status.uidvalidity != 0 && !client->nonpermanent_modseqs) {
+		if ((ret = select_qresync(ctx)) < 0) {
+			client_send_box_error(ctx->cmd, ctx->box);
+			return -1;
+		}
+	} else {
+		ret = 1;
+	}
+	return ret;
+}
+
+static void close_selected_mailbox(struct client *client)
+{
+	if (client->mailbox == NULL)
+		return;
+
+	imap_client_close_mailbox(client);
+	/* CLOSED response is required by QRESYNC */
+	client_send_line(client, "* OK [CLOSED] Previous mailbox closed.");
+}
+
+bool cmd_select_full(struct client_command_context *cmd, bool readonly)
+{
+	struct client *client = cmd->client;
+	struct imap_select_context *ctx;
+	const struct imap_arg *args, *list_args;
+	const char *mailbox, *client_error;
+	int ret;
+
+	/* <mailbox> [(optional parameters)] */
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (!imap_arg_get_astring(args, &mailbox)) {
+		close_selected_mailbox(client);
+		client_send_command_error(cmd, "Invalid arguments.");
+		return FALSE;
+	}
+
+	ctx = p_new(cmd->pool, struct imap_select_context, 1);
+	ctx->cmd = cmd;
+	ctx->ns = client_find_namespace_full(cmd->client, &mailbox, &client_error);
+	if (ctx->ns == NULL) {
+		/* send * OK [CLOSED] before the tagged reply */
+		close_selected_mailbox(client);
+		client_send_tagline(cmd, client_error);
+		return TRUE;
+	}
+
+	if (imap_arg_get_list(&args[1], &list_args)) {
+		if (!select_parse_options(ctx, list_args, &client_error)) {
+			select_context_free(ctx);
+			/* send * OK [CLOSED] before the tagged reply */
+			close_selected_mailbox(client);
+			client_send_command_error(ctx->cmd, client_error);
+			return TRUE;
+		}
+	}
+
+	i_assert(client->mailbox_change_lock == NULL);
+	client->mailbox_change_lock = cmd;
+
+	close_selected_mailbox(client);
+
+	if (ctx->condstore) {
+		/* Enable while no mailbox is opened to avoid sending
+		   HIGHESTMODSEQ for previously opened mailbox */
+		client_enable(client, imap_feature_condstore);
+	}
+
+	ret = select_open(ctx, mailbox, readonly);
+	if (ret == 0)
+		return FALSE;
+	cmd_select_finish(ctx, ret);
+	return TRUE;
+}
+
+bool cmd_select(struct client_command_context *cmd)
+{
+	return cmd_select_full(cmd, FALSE);
+}
diff --git a/src/imap/cmd-setmetadata.c b/src/imap/cmd-setmetadata.c
new file mode 100644
index 0000000..247afce
--- /dev/null
+++ b/src/imap/cmd-setmetadata.c
@@ -0,0 +1,378 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "ioloop.h"
+#include "istream.h"
+#include "istream-seekable.h"
+#include "ostream.h"
+#include "str.h"
+#include "imap-metadata.h"
+#include "mail-storage-private.h"
+
+#define METADATA_MAX_INMEM_SIZE (1024*128)
+
+struct imap_setmetadata_context {
+	struct client_command_context *cmd;
+	struct imap_parser *parser;
+
+	struct mailbox *box;
+	struct imap_metadata_transaction *trans;
+
+	char *entry_name;
+	uoff_t entry_value_len;
+	struct istream *input;
+	bool failed;
+	bool cmd_error_sent;
+	bool storage_failure;
+};
+
+static void cmd_setmetadata_deinit(struct imap_setmetadata_context *ctx)
+{
+	o_stream_set_flush_callback(ctx->cmd->client->output,
+				    client_output, ctx->cmd->client);
+
+	ctx->cmd->client->input_lock = NULL;
+	imap_parser_unref(&ctx->parser);
+	if (ctx->trans != NULL)
+		imap_metadata_transaction_rollback(&ctx->trans);
+	if (ctx->box != NULL && ctx->box != ctx->cmd->client->mailbox)
+		mailbox_free(&ctx->box);
+	i_free(ctx->entry_name);
+}
+
+static int
+cmd_setmetadata_parse_entryvalue(struct imap_setmetadata_context *ctx,
+				 const char **entry_r,
+				 const struct imap_arg **value_r)
+{
+	const struct imap_arg *args;
+	const char *name, *client_error;
+	enum imap_parser_error parse_error;
+	int ret;
+
+	/* parse the entry name */
+	ret = imap_parser_read_args(ctx->parser, 1,
+				    IMAP_PARSE_FLAG_INSIDE_LIST, &args);
+	if (ret >= 0) {
+		if (ret == 0) {
+			/* ')' found */
+			*entry_r = NULL;
+			return 1;
+		}
+		if (!imap_arg_get_astring(args, &name)) {
+			client_send_command_error(ctx->cmd,
+						  "Entry name isn't astring");
+			return -1;
+		}
+
+		ret = imap_parser_read_args(ctx->parser, 2,
+					    IMAP_PARSE_FLAG_INSIDE_LIST |
+					    IMAP_PARSE_FLAG_LITERAL_SIZE |
+					    IMAP_PARSE_FLAG_LITERAL8, &args);
+	}
+	if (ret < 0) {
+		if (ret == -2)
+			return 0;
+		client_error = imap_parser_get_error(ctx->parser, &parse_error);
+		switch (parse_error) {
+		case IMAP_PARSE_ERROR_NONE:
+			i_unreached();
+		case IMAP_PARSE_ERROR_LITERAL_TOO_BIG:
+			client_disconnect_with_error(ctx->cmd->client,
+						     client_error);
+			break;
+		default:
+			client_send_command_error(ctx->cmd, client_error);
+			break;
+		}
+		return -1;
+	}
+	if (args[1].type == IMAP_ARG_EOL) {
+		client_send_command_error(ctx->cmd, "Entry value missing");
+		return -1;
+	}
+	if (args[1].type == IMAP_ARG_LIST) {
+		client_send_command_error(ctx->cmd, "Entry value can't be a list");
+		return -1;
+	}
+	if (!ctx->cmd_error_sent &&
+	    !imap_metadata_verify_entry_name(name, &client_error)) {
+		client_send_command_error(ctx->cmd, client_error);
+		ctx->cmd_error_sent = TRUE;
+	}
+	if (ctx->cmd_error_sent) {
+		ctx->cmd->param_error = FALSE;
+		ctx->cmd->state = CLIENT_COMMAND_STATE_WAIT_INPUT;
+
+		ctx->failed = TRUE;
+		if (args[1].type == IMAP_ARG_LITERAL_SIZE) {
+			/* client won't see "+ OK", so we can abort
+			   immediately */
+			ctx->cmd->client->input_skip_line = FALSE;
+			return -1;
+		}
+	}
+
+	/* entry names are case-insensitive. handle this by using only
+	   lowercase names. */
+	*entry_r = t_str_lcase(name);
+	*value_r = &args[1];
+	return 1;
+}
+
+static int
+cmd_setmetadata_entry_read_stream(struct imap_setmetadata_context *ctx)
+{
+	const unsigned char *data;
+	size_t size;
+	struct mail_attribute_value value;
+	int ret;
+
+	while ((ret = i_stream_read_more(ctx->input, &data, &size)) > 0)
+		i_stream_skip(ctx->input, size);
+	if (ret == 0)
+		return 0;
+
+	if (ctx->input->v_offset != ctx->entry_value_len) {
+		/* client disconnected */
+		i_assert(ctx->input->eof);
+		return -1;
+	}
+
+	/* finished reading the value */
+	i_stream_seek(ctx->input, 0);
+
+	if (ctx->failed) {
+		i_stream_unref(&ctx->input);
+		return 1;
+	}
+
+	i_zero(&value);
+	value.value_stream = ctx->input;
+	if (imap_metadata_set(ctx->trans, ctx->entry_name, &value) < 0) {
+		/* delay reporting the failure so we'll finish
+		   reading the command input */
+		ctx->storage_failure = TRUE;
+		ctx->failed = TRUE;
+	}
+	i_stream_unref(&ctx->input);
+	return 1;
+}
+
+static int
+cmd_setmetadata_entry(struct imap_setmetadata_context *ctx,
+		      const char *entry_name,
+		      const struct imap_arg *entry_value)
+{
+	struct istream *inputs[2];
+	struct mail_attribute_value value;
+	string_t *path;
+	int ret;
+
+	switch (entry_value->type) {
+	case IMAP_ARG_NIL:
+	case IMAP_ARG_ATOM:
+	case IMAP_ARG_STRING:
+		/* we have the value already */
+		if (ctx->failed)
+			return 1;
+		i_zero(&value);
+		/* NOTE: The RFC doesn't allow atoms as value, but since
+		   Dovecot has traditionally supported it this is kept for
+		   backwards compatibility just in case some client is
+		   using it. */
+		if (entry_value->type == IMAP_ARG_NIL)
+			;
+		else if (!imap_arg_get_atom(entry_value, &value.value))
+			value.value = imap_arg_as_nstring(entry_value);
+		ret = imap_metadata_set(ctx->trans, entry_name, &value);
+		if (ret < 0) {
+			/* delay reporting the failure so we'll finish
+			   reading the command input */
+			ctx->storage_failure = TRUE;
+			ctx->failed = TRUE;
+		}
+		return 1;
+	case IMAP_ARG_LITERAL_SIZE:
+		o_stream_nsend(ctx->cmd->client->output, "+ OK\r\n", 6);
+		o_stream_uncork(ctx->cmd->client->output);
+		o_stream_cork(ctx->cmd->client->output);
+		/* fall through */
+	case IMAP_ARG_LITERAL_SIZE_NONSYNC:
+		i_free(ctx->entry_name);
+		ctx->entry_name = i_strdup(entry_name);
+		ctx->entry_value_len = imap_arg_as_literal_size(entry_value);
+
+		inputs[0] = i_stream_create_limit(ctx->cmd->client->input,
+						  ctx->entry_value_len);
+		inputs[1] = NULL;
+
+		path = t_str_new(128);
+		mail_user_set_get_temp_prefix(path, ctx->cmd->client->user->set);
+		ctx->input = i_stream_create_seekable_path(inputs,
+					METADATA_MAX_INMEM_SIZE, str_c(path));
+		i_stream_set_name(ctx->input, i_stream_get_name(inputs[0]));
+		i_stream_unref(&inputs[0]);
+		return cmd_setmetadata_entry_read_stream(ctx);
+	case IMAP_ARG_LITERAL:
+	case IMAP_ARG_LIST:
+	case IMAP_ARG_EOL:
+		break;
+	}
+	i_unreached();
+}
+
+static bool cmd_setmetadata_continue(struct client_command_context *cmd)
+{
+	struct imap_setmetadata_context *ctx = cmd->context;
+	const char *entry, *client_error;
+	enum mail_error error;
+	const struct imap_arg *value;
+	int ret;
+
+	if (cmd->cancel) {
+		cmd_setmetadata_deinit(ctx);
+		return TRUE;
+	}
+
+	if (ctx->input != NULL) {
+		if ((ret = cmd_setmetadata_entry_read_stream(ctx)) == 0)
+			return FALSE;
+		if (ret < 0) {
+			cmd_setmetadata_deinit(ctx);
+			return TRUE;
+		}
+	}
+
+	while ((ret = cmd_setmetadata_parse_entryvalue(ctx, &entry, &value)) > 0 &&
+	       entry != NULL) {
+		ret = ctx->failed ? 1 :
+			cmd_setmetadata_entry(ctx, entry, value);
+		imap_parser_reset(ctx->parser);
+		if (ret <= 0)
+			break;
+	}
+	if (ret == 0)
+		return 0;
+
+	if (ret < 0 || ctx->cmd_error_sent) {
+		/* already sent the error to client */ ;
+	} else if (ctx->storage_failure) {
+		if (ctx->box == NULL)
+			client_disconnect_if_inconsistent(cmd->client);
+		client_error = imap_metadata_transaction_get_last_error
+			(ctx->trans, &error);
+		client_send_tagline(cmd,
+			imap_get_error_string(cmd, client_error, error));
+	} else if (imap_metadata_transaction_commit(&ctx->trans, 
+						&error, &client_error) < 0) {
+		if (ctx->box == NULL)
+			client_disconnect_if_inconsistent(cmd->client);
+		client_send_tagline(cmd,
+			imap_get_error_string(cmd, client_error, error));
+	} else {
+		client_send_tagline(cmd, "OK Setmetadata completed.");
+	}
+	cmd_setmetadata_deinit(ctx);
+	return TRUE;
+}
+
+static bool
+cmd_setmetadata_start(struct imap_setmetadata_context *ctx)
+{
+	struct client_command_context *cmd = ctx->cmd;
+	struct client *client = cmd->client;
+
+	imap_metadata_transaction_validated_only(ctx->trans,
+		!cmd->client->set->imap_metadata);
+	/* we support large literals, so read the values from client
+	   asynchronously the same way as APPEND does. */
+	client->input_lock = cmd;
+	ctx->parser = imap_parser_create(client->input, client->output,
+					 client->set->imap_max_line_length);
+	if (client->set->imap_literal_minus)
+		imap_parser_enable_literal_minus(ctx->parser);
+	o_stream_unset_flush_callback(client->output);
+
+	cmd->func = cmd_setmetadata_continue;
+	cmd->context = ctx;
+	return cmd_setmetadata_continue(cmd);
+}
+
+static bool
+cmd_setmetadata_server(struct imap_setmetadata_context *ctx)
+{
+	ctx->trans = imap_metadata_transaction_begin_server(ctx->cmd->client->user);
+	return cmd_setmetadata_start(ctx);
+}
+
+static bool
+cmd_setmetadata_mailbox(struct imap_setmetadata_context *ctx,
+	const char *mailbox)
+{
+	struct client_command_context *cmd = ctx->cmd;
+	struct client *client = cmd->client;
+	struct mail_namespace *ns;
+
+	ns = client_find_namespace(cmd, &mailbox);
+	if (ns == NULL)
+		return TRUE;
+
+	if (client->mailbox != NULL && !client->mailbox_examined &&
+	    mailbox_equals(client->mailbox, ns, mailbox))
+		ctx->box = client->mailbox;
+	else {
+		ctx->box = mailbox_alloc(ns->list, mailbox,
+					 MAILBOX_FLAG_ATTRIBUTE_SESSION);
+		enum mailbox_existence existence;
+		if (mailbox_exists(ctx->box, TRUE, &existence) < 0) {
+			client_send_box_error(cmd, ctx->box);
+			mailbox_free(&ctx->box);
+			return TRUE;
+		} else if (existence == MAILBOX_EXISTENCE_NONE) {
+			const char *err = t_strdup_printf(MAIL_ERRSTR_MAILBOX_NOT_FOUND,
+							  mailbox_get_vname(ctx->box));
+			mail_storage_set_error(ctx->box->storage, MAIL_ERROR_NOTFOUND, err);
+			client_send_box_error(cmd, ctx->box);
+			mailbox_free(&ctx->box);
+			return TRUE;
+		}
+	}
+	event_add_str(ctx->cmd->global_event, "mailbox",
+		      mailbox_get_vname(ctx->box));
+	ctx->trans = imap_metadata_transaction_begin(ctx->box);
+	return cmd_setmetadata_start(ctx);
+}
+
+bool cmd_setmetadata(struct client_command_context *cmd)
+{
+	struct imap_setmetadata_context *ctx;
+	const struct imap_arg *args;
+	const char *mailbox;
+	int ret;
+
+	ret = imap_parser_read_args(cmd->parser, 2,
+				    IMAP_PARSE_FLAG_STOP_AT_LIST, &args);
+	if (ret == -1) {
+		client_send_command_error(cmd, NULL);
+		return TRUE;
+	}
+	if (ret == -2)
+		return FALSE;
+	if (!imap_arg_get_astring(&args[0], &mailbox) ||
+	    args[1].type != IMAP_ARG_LIST) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+
+	ctx = p_new(cmd->pool, struct imap_setmetadata_context, 1);
+	ctx->cmd = cmd;
+	ctx->cmd->context = ctx;
+
+	if (mailbox[0] == '\0') {
+		/* server attribute */
+		return cmd_setmetadata_server(ctx);
+	}
+
+	return cmd_setmetadata_mailbox(ctx, mailbox);
+}
diff --git a/src/imap/cmd-sort.c b/src/imap/cmd-sort.c
new file mode 100644
index 0000000..6515a67
--- /dev/null
+++ b/src/imap/cmd-sort.c
@@ -0,0 +1,142 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "buffer.h"
+#include "imap-commands.h"
+#include "imap-search-args.h"
+#include "imap-search.h"
+
+struct sort_name {
+	enum mail_sort_type type;
+	const char *name;
+};
+
+static struct sort_name sort_names[] = {
+	{ MAIL_SORT_ARRIVAL,		"arrival" },
+	{ MAIL_SORT_CC,			"cc" },
+	{ MAIL_SORT_DATE,		"date" },
+	{ MAIL_SORT_FROM,		"from" },
+	{ MAIL_SORT_SIZE,		"size" },
+	{ MAIL_SORT_SUBJECT,		"subject" },
+	{ MAIL_SORT_TO,			"to" },
+	{ MAIL_SORT_RELEVANCY,		"x-score" }, /* FIXME: obsolete */
+	{ MAIL_SORT_RELEVANCY,		"relevancy" },
+	{ MAIL_SORT_DISPLAYFROM,	"displayfrom" },
+	{ MAIL_SORT_DISPLAYTO,		"displayto" },
+
+	{ MAIL_SORT_END,		NULL }
+};
+
+static int
+get_sort_program(struct client_command_context *cmd,
+		 const struct imap_arg *args,
+		 enum mail_sort_type program[MAX_SORT_PROGRAM_SIZE])
+{
+	enum mail_sort_type mask = 0;
+	const char *arg;
+	unsigned int i, pos;
+	bool reverse, last_reverse;
+
+	if (IMAP_ARG_IS_EOL(args)) {
+		/* empty list */
+		client_send_command_error(cmd, "Empty sort program.");
+		return -1;
+	}
+
+	pos = 0; reverse = last_reverse = FALSE;
+	for (; imap_arg_get_astring(args, &arg); args++) {
+		last_reverse = strcasecmp(arg, "reverse") == 0;
+		if (last_reverse) {
+			reverse = !reverse;
+			continue;
+		}
+
+		for (i = 0; sort_names[i].type != MAIL_SORT_END; i++) {
+			if (strcasecmp(arg, sort_names[i].name) == 0)
+				break;
+		}
+
+		if (sort_names[i].type == MAIL_SORT_END) {
+			client_send_command_error(cmd, t_strconcat(
+				"Unknown sort argument: ", arg, NULL));
+			return -1;
+		}
+
+		if ((mask & sort_names[i].type) != 0)
+			continue;
+		mask |= sort_names[i].type;
+
+		/* @UNSAFE: mask check should prevent us from ever
+		   overflowing */
+		i_assert(pos < MAX_SORT_PROGRAM_SIZE-1);
+		program[pos++] = sort_names[i].type |
+			(reverse ? MAIL_SORT_FLAG_REVERSE : 0);
+		reverse = FALSE;
+	}
+	if (last_reverse) {
+		client_send_command_error(cmd, "Sort list ends with REVERSE.");
+		return -1;
+	}
+	program[pos] = MAIL_SORT_END;
+
+	if (!IMAP_ARG_IS_EOL(args)) {
+		client_send_command_error(cmd,
+					  "Invalid sort list argument.");
+		return -1;
+	}
+
+	return 0;
+}
+
+bool cmd_sort(struct client_command_context *cmd)
+{
+	struct imap_search_context *ctx;
+	struct mail_search_args *sargs;
+	enum mail_sort_type sort_program[MAX_SORT_PROGRAM_SIZE];
+	const struct imap_arg *args, *list_args;
+	const char *charset;
+	int ret;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	ctx = p_new(cmd->pool, struct imap_search_context, 1);
+	ctx->cmd = cmd;
+
+	if ((ret = cmd_search_parse_return_if_found(ctx, &args)) <= 0) {
+		/* error / waiting for unambiguity */
+		return ret < 0;
+	}
+
+	/* sort program */
+	if (!imap_arg_get_list(args, &list_args)) {
+		client_send_command_error(cmd, "Invalid sort argument.");
+		imap_search_context_free(ctx);
+		return TRUE;
+	}
+
+	if (get_sort_program(cmd, list_args, sort_program) < 0) {
+		imap_search_context_free(ctx);
+		return TRUE;
+	}
+	args++;
+
+	/* charset */
+	if (!imap_arg_get_astring(args, &charset)) {
+		client_send_command_error(cmd, "Invalid charset argument.");
+		imap_search_context_free(ctx);
+		return TRUE;
+	}
+	args++;
+
+	ret = imap_search_args_build(cmd, args, charset, &sargs);
+	if (ret <= 0) {
+		imap_search_context_free(ctx);
+		return ret < 0;
+	}
+
+	return imap_search_start(ctx, sargs, sort_program);
+}
diff --git a/src/imap/cmd-status.c b/src/imap/cmd-status.c
new file mode 100644
index 0000000..69c0a51
--- /dev/null
+++ b/src/imap/cmd-status.c
@@ -0,0 +1,54 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-resp-code.h"
+#include "imap-commands.h"
+#include "imap-sync.h"
+#include "imap-status.h"
+
+bool cmd_status(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	const struct imap_arg *args, *list_args;
+	struct imap_status_items items;
+	struct imap_status_result result;
+	struct mail_namespace *ns;
+	const char *mailbox, *orig_mailbox;
+	bool selected_mailbox;
+
+	/* <mailbox> <status items> */
+	if (!client_read_args(cmd, 2, 0, &args))
+		return FALSE;
+
+	if (!imap_arg_get_astring(&args[0], &mailbox) ||
+	    !imap_arg_get_list(&args[1], &list_args)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+
+	/* get the items client wants */
+	if (imap_status_parse_items(cmd, list_args, &items) < 0)
+		return TRUE;
+
+	orig_mailbox = mailbox;
+	ns = client_find_namespace(cmd, &mailbox);
+	if (ns == NULL)
+		return TRUE;
+
+	event_add_str(cmd->global_event, "mailbox", mailbox);
+	selected_mailbox = client->mailbox != NULL &&
+		mailbox_equals(client->mailbox, ns, mailbox);
+	if (imap_status_get(cmd, ns, mailbox, &items, &result) < 0) {
+		client_send_tagline(cmd, result.errstr);
+		return TRUE;
+	}
+
+	imap_status_send(client, orig_mailbox, &items, &result);
+	if (!selected_mailbox)
+		client_send_tagline(cmd, "OK Status completed.");
+	else {
+		client_send_tagline(cmd, "OK ["IMAP_RESP_CODE_CLIENTBUG"] "
+				    "Status on selected mailbox completed.");
+	}
+	return TRUE;
+}
diff --git a/src/imap/cmd-store.c b/src/imap/cmd-store.c
new file mode 100644
index 0000000..126c042
--- /dev/null
+++ b/src/imap/cmd-store.c
@@ -0,0 +1,261 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "seq-range-array.h"
+#include "str.h"
+#include "imap-commands.h"
+#include "imap-search-args.h"
+#include "imap-util.h"
+
+
+struct imap_store_context {
+	struct client_command_context *cmd;
+	uint64_t max_modseq;
+
+	enum mail_flags flags;
+	struct mail_keywords *keywords;
+
+	enum modify_type modify_type;
+	bool silent;
+};
+
+static bool
+get_modify_type(struct imap_store_context *ctx, const char *type)
+{
+	if (*type == '+') {
+		ctx->modify_type = MODIFY_ADD;
+		type++;
+	} else if (*type == '-') {
+		ctx->modify_type = MODIFY_REMOVE;
+		type++;
+	} else {
+		ctx->modify_type = MODIFY_REPLACE;
+	}
+
+	if (strncasecmp(type, "FLAGS", 5) != 0)
+		return FALSE;
+
+	ctx->silent = strcasecmp(type+5, ".SILENT") == 0;
+	if (!ctx->silent && type[5] != '\0')
+		return FALSE;
+	return TRUE;
+}
+
+static bool
+store_parse_modifiers(struct imap_store_context *ctx,
+		      const struct imap_arg *args)
+{
+	const char *name, *value;
+
+	for (; !IMAP_ARG_IS_EOL(args); args += 2) {
+		if (!imap_arg_get_atom(&args[0], &name) ||
+		    !imap_arg_get_atom(&args[1], &value)) {
+			client_send_command_error(ctx->cmd,
+				"Invalid STORE modifiers.");
+			return FALSE;
+		}
+
+		if (strcasecmp(name, "UNCHANGEDSINCE") == 0) {
+			if (ctx->cmd->client->nonpermanent_modseqs) {
+				client_send_command_error(ctx->cmd,
+					"STORE UNCHANGEDSINCE can't be used with non-permanent modseqs");
+				return FALSE;
+			}
+			if (str_to_uint64(value, &ctx->max_modseq) < 0) {
+				client_send_command_error(ctx->cmd,
+							  "Invalid modseq");
+				return FALSE;
+			}
+			client_enable(ctx->cmd->client, imap_feature_condstore);
+		} else {
+			client_send_command_error(ctx->cmd,
+						  "Unknown STORE modifier");
+			return FALSE;
+		}
+	}
+	return TRUE;
+}
+
+static bool
+store_parse_args(struct imap_store_context *ctx, const struct imap_arg *args)
+{
+	struct client_command_context *cmd = ctx->cmd;
+	const struct imap_arg *list_args;
+	const char *type;
+	const char *const *keywords_list = NULL;
+
+	ctx->max_modseq = (uint64_t)-1;
+	if (imap_arg_get_list(args, &list_args)) {
+		if (!store_parse_modifiers(ctx, list_args))
+			return FALSE;
+		args++;
+	}
+
+	if (!imap_arg_get_astring(args, &type) ||
+	    !get_modify_type(ctx, type)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return FALSE;
+	}
+	args++;
+
+	if (imap_arg_get_list(args, &list_args)) {
+		if (!client_parse_mail_flags(cmd, list_args,
+					     &ctx->flags, &keywords_list))
+			return FALSE;
+	} else {
+		if (!client_parse_mail_flags(cmd, args,
+					     &ctx->flags, &keywords_list))
+			return FALSE;
+	}
+
+	if (keywords_list != NULL || ctx->modify_type == MODIFY_REPLACE) {
+		if (mailbox_keywords_create(cmd->client->mailbox, keywords_list,
+					    &ctx->keywords) < 0) {
+			/* invalid keywords */
+			client_send_box_error(cmd, cmd->client->mailbox);
+			return FALSE;
+		}
+	}
+	return TRUE;
+}
+
+bool cmd_store(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	const struct imap_arg *args;
+	struct mail_search_args *search_args;
+	struct mail_search_context *search_ctx;
+        struct mailbox_transaction_context *t;
+	struct mail *mail;
+	struct imap_store_context ctx;
+	ARRAY_TYPE(seq_range) modified_set, uids;
+	enum mailbox_transaction_flags flags = 0;
+	enum imap_sync_flags imap_sync_flags = 0;
+	const char *set, *reply, *tagged_reply;
+	string_t *str;
+	int ret;
+	bool update_deletes;
+	unsigned int deleted_count;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	if (!imap_arg_get_atom(args, &set)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+	ret = imap_search_get_seqset(cmd, set, cmd->uid, &search_args);
+	if (ret <= 0)
+		return ret < 0;
+
+	i_zero(&ctx);
+	ctx.cmd = cmd;
+	if (!store_parse_args(&ctx, ++args)) {
+		mail_search_args_unref(&search_args);
+		return TRUE;
+	}
+
+	if (client->mailbox_examined) {
+		mail_search_args_unref(&search_args);
+		if (ctx.max_modseq < (uint64_t)-1)
+			reply = "NO CONDSTORE failed: Mailbox is read-only.";
+		else
+			reply = "OK Store ignored with read-only mailbox.";
+		return cmd_sync(cmd, MAILBOX_SYNC_FLAG_FAST |
+				(cmd->uid ? 0 : MAILBOX_SYNC_FLAG_NO_EXPUNGES),
+				0, reply);
+	}
+
+	if (ctx.silent)
+		flags |= MAILBOX_TRANSACTION_FLAG_HIDE;
+	if (ctx.max_modseq < (uint64_t)-1) {
+		/* update modseqs so we can check them early */
+		flags |= MAILBOX_TRANSACTION_FLAG_REFRESH;
+	}
+
+	t = mailbox_transaction_begin(client->mailbox, flags,
+				      imap_client_command_get_reason(cmd));
+
+	search_ctx = mailbox_search_init(t, search_args, NULL,
+					 MAIL_FETCH_FLAGS, NULL);
+	mail_search_args_unref(&search_args);
+
+	i_array_init(&modified_set, 64);
+	if (ctx.max_modseq < (uint64_t)-1) {
+		/* STORE UNCHANGEDSINCE is being used */
+		mailbox_transaction_set_max_modseq(t, ctx.max_modseq,
+						   &modified_set);
+	}
+
+	update_deletes = (ctx.flags & MAIL_DELETED) != 0 &&
+		ctx.modify_type != MODIFY_REMOVE;
+	deleted_count = 0;
+	while (mailbox_search_next(search_ctx, &mail)) {
+		if (ctx.max_modseq < (uint64_t)-1) {
+			/* check early so there's less work for transaction
+			   commit if something has to be cancelled */
+			if (mail_get_modseq(mail) > ctx.max_modseq) {
+				seq_range_array_add(&modified_set, mail->seq);
+				continue;
+			}
+		}
+		if (update_deletes) {
+			if ((mail_get_flags(mail) & MAIL_DELETED) == 0)
+				deleted_count++;
+		}
+		if (ctx.modify_type == MODIFY_REPLACE || ctx.flags != 0)
+			mail_update_flags(mail, ctx.modify_type, ctx.flags);
+		if (ctx.modify_type == MODIFY_REPLACE || ctx.keywords != NULL) {
+			mail_update_keywords(mail, ctx.modify_type,
+					     ctx.keywords);
+		}
+	}
+
+	if (ctx.keywords != NULL)
+		mailbox_keywords_unref(&ctx.keywords);
+
+	ret = mailbox_search_deinit(&search_ctx);
+	if (ret < 0)
+		mailbox_transaction_rollback(&t);
+	 else
+		ret = mailbox_transaction_commit(&t);
+	if (ret < 0) {
+		array_free(&modified_set);
+		client_send_box_error(cmd, client->mailbox);
+		return TRUE;
+	}
+	client->deleted_count += deleted_count;
+
+	if (array_count(&modified_set) == 0)
+		tagged_reply = "OK Store completed.";
+	else {
+		if (cmd->uid) {
+			i_array_init(&uids, array_count(&modified_set)*2);
+			mailbox_get_uid_range(client->mailbox, &modified_set,
+					      &uids);
+			array_free(&modified_set);
+			modified_set = uids;
+		}
+		str = str_new(cmd->pool, 256);
+		str_append(str, "OK [MODIFIED ");
+		imap_write_seq_range(str, &modified_set);
+		str_append(str, "] Conditional store failed.");
+		tagged_reply = str_c(str);
+	}
+	array_free(&modified_set);
+
+	/* With UID STORE we have to return UID for the flags as well.
+	   Unfortunately we don't have the ability to separate those
+	   flag changes that were caused by UID STORE and those that
+	   came externally, so we'll just send the UID for all flag
+	   changes that we see. */
+	if (cmd->uid && (!ctx.silent ||
+			 client_has_enabled(client, imap_feature_condstore)))
+		imap_sync_flags |= IMAP_SYNC_FLAG_SEND_UID;
+
+	return cmd_sync(cmd, (cmd->uid ? 0 : MAILBOX_SYNC_FLAG_NO_EXPUNGES),
+			imap_sync_flags, tagged_reply);
+}
diff --git a/src/imap/cmd-subscribe.c b/src/imap/cmd-subscribe.c
new file mode 100644
index 0000000..03c2684
--- /dev/null
+++ b/src/imap/cmd-subscribe.c
@@ -0,0 +1,87 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-utf7.h"
+#include "imap-commands.h"
+#include "mail-namespace.h"
+
+static bool
+subscribe_is_valid_name(struct client_command_context *cmd, struct mailbox *box)
+{
+	enum mailbox_existence existence;
+
+	if (mailbox_exists(box, TRUE, &existence) < 0) {
+		client_send_box_error(cmd, box);
+		return FALSE;
+	}
+	if (existence == MAILBOX_EXISTENCE_NONE) {
+		client_send_tagline(cmd, t_strdup_printf(
+			"NO "MAIL_ERRSTR_MAILBOX_NOT_FOUND,
+			mailbox_get_vname(box)));
+		return FALSE;
+	}
+	return TRUE;
+}
+
+static bool str_ends_with_char(const char *str, char c)
+{
+	size_t len = strlen(str);
+
+	return len > 0 && str[len-1] == c;
+}
+
+bool cmd_subscribe_full(struct client_command_context *cmd, bool subscribe)
+{
+	struct mail_namespace *ns;
+	struct mailbox *box, *box2;
+	const char *mailbox, *orig_mailbox;
+	bool unsubscribed_mailbox2;
+	char sep;
+
+	/* <mailbox> */
+	if (!client_read_string_args(cmd, 1, &mailbox))
+		return FALSE;
+	orig_mailbox = mailbox;
+
+	ns = client_find_namespace(cmd, &mailbox);
+	if (ns == NULL)
+		return TRUE;
+
+	box = mailbox_alloc(ns->list, mailbox, 0);
+	event_add_str(cmd->global_event, "mailbox", mailbox_get_vname(box));
+	if (subscribe) {
+		if (!subscribe_is_valid_name(cmd, box)) {
+			mailbox_free(&box);
+			return TRUE;
+		}
+	}
+
+	sep = mail_namespace_get_sep(ns);
+	unsubscribed_mailbox2 = FALSE;
+	if (!subscribe &&
+	    str_ends_with_char(orig_mailbox, sep) &&
+	    !str_ends_with_char(mailbox, sep)) {
+		/* try to unsubscribe both "box" and "box/" */
+		const char *name2 = t_strdup_printf("%s%c", mailbox, sep);
+		box2 = mailbox_alloc(ns->list, name2, 0);
+		if (mailbox_set_subscribed(box2, FALSE) == 0)
+			unsubscribed_mailbox2 = TRUE;
+		mailbox_free(&box2);
+	}
+
+	if (mailbox_set_subscribed(box, subscribe) < 0 &&
+	    !unsubscribed_mailbox2) {
+		client_send_box_error(cmd, box);
+	} else {
+		client_send_tagline(cmd, subscribe ?
+				    "OK Subscribe completed." :
+				    "OK Unsubscribe completed.");
+	}
+	mailbox_free(&box);
+	return TRUE;
+}
+
+bool cmd_subscribe(struct client_command_context *cmd)
+{
+	return cmd_subscribe_full(cmd, TRUE);
+}
diff --git a/src/imap/cmd-thread.c b/src/imap/cmd-thread.c
new file mode 100644
index 0000000..64388d5
--- /dev/null
+++ b/src/imap/cmd-thread.c
@@ -0,0 +1,294 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "ostream.h"
+#include "imap-base-subject.h"
+#include "imap-commands.h"
+#include "imap-search-args.h"
+#include "mail-thread.h"
+
+static int imap_thread_write(struct mail_thread_iterate_context *iter,
+			     string_t *str, bool root)
+{
+	const struct mail_thread_child_node *node;
+	struct mail_thread_iterate_context *child_iter;
+	unsigned int count;
+	int ret = 0;
+
+	count = mail_thread_iterate_count(iter);
+	if (count == 0)
+		return 0;
+
+	if (count == 1 && !root) {
+		/* only one child - special case to avoid extra parenthesis */
+		node = mail_thread_iterate_next(iter, &child_iter);
+		str_printfa(str, "%u", node->uid);
+		if (child_iter != NULL) {
+			str_append_c(str, ' ');
+			T_BEGIN {
+				ret = imap_thread_write(child_iter, str, FALSE);
+			} T_END;
+			if (mail_thread_iterate_deinit(&child_iter) < 0)
+				return -1;
+		}
+		return ret;
+	}
+
+	while ((node = mail_thread_iterate_next(iter, &child_iter)) != NULL) {
+		if (child_iter == NULL) {
+			/* no children */
+			str_printfa(str, "(%u)", node->uid);
+		} else {
+			/* node with children */
+			str_append_c(str, '(');
+			if (node->uid != 0)
+				str_printfa(str, "%u ", node->uid);
+			T_BEGIN {
+				ret = imap_thread_write(child_iter, str, FALSE);
+			} T_END;
+			if (mail_thread_iterate_deinit(&child_iter) < 0 ||
+			    ret < 0)
+				return -1;
+			str_append_c(str, ')');
+		}
+	}
+	return 0;
+}
+
+static int
+imap_thread_write_reply(struct mail_thread_context *ctx, string_t *str,
+			enum mail_thread_type thread_type, bool write_seqs)
+{
+	struct mail_thread_iterate_context *iter;
+	int ret;
+
+	iter = mail_thread_iterate_init(ctx, thread_type, write_seqs);
+	str_append(str, "* THREAD ");
+	T_BEGIN {
+		ret = imap_thread_write(iter, str, TRUE);
+	} T_END;
+	if (mail_thread_iterate_deinit(&iter) < 0)
+		ret = -1;
+
+	str_append(str, "\r\n");
+	return ret;
+}
+
+static int imap_thread(struct client_command_context *cmd,
+		       struct mail_search_args *search_args,
+		       enum mail_thread_type thread_type)
+{
+	struct mail_thread_context *ctx;
+	string_t *str;
+	int ret;
+
+	i_assert(thread_type == MAIL_THREAD_REFERENCES ||
+		 thread_type == MAIL_THREAD_REFS);
+
+	str = str_new(default_pool, 1024);
+	ret = mail_thread_init(cmd->client->mailbox,
+			       search_args, &ctx);
+	if (ret == 0) {
+		ret = imap_thread_write_reply(ctx, str, thread_type,
+					      !cmd->uid);
+		mail_thread_deinit(&ctx);
+	}
+
+	if (ret == 0)
+		o_stream_nsend(cmd->client->output, str_data(str), str_len(str));
+	str_free(&str);
+	return ret;
+}
+
+struct orderedsubject_thread {
+	time_t timestamp;
+	ARRAY_TYPE(uint32_t) msgs;
+};
+
+static int orderedsubject_thread_cmp(const struct orderedsubject_thread *t1,
+				     const struct orderedsubject_thread *t2)
+{
+	const uint32_t *m1, *m2;
+
+	if (t1->timestamp < t2->timestamp)
+		return -1;
+	if (t1->timestamp > t2->timestamp)
+		return 1;
+
+	m1 = array_front(&t1->msgs);
+	m2 = array_front(&t2->msgs);
+	if (*m1 < *m2)
+		return -1;
+	if (*m1 > *m2)
+		return 1;
+	i_unreached();
+}
+
+static void
+imap_orderedsubject_thread_write(struct ostream *output, string_t *reply,
+				 const struct orderedsubject_thread *thread)
+{
+	const uint32_t *msgs;
+	unsigned int i, count;
+
+	if (str_len(reply) > 128-10) {
+		o_stream_nsend(output, str_data(reply), str_len(reply));
+		str_truncate(reply, 0);
+	}
+
+	msgs = array_get(&thread->msgs, &count);
+	switch (count) {
+	case 1:
+		str_printfa(reply, "(%u)", msgs[0]);
+		break;
+	case 2:
+		str_printfa(reply, "(%u %u)", msgs[0], msgs[1]);
+		break;
+	default:
+		/* (1 (2)(3)) */
+		str_printfa(reply, "(%u ", msgs[0]);
+		for (i = 1; i < count; i++) {
+			if (str_len(reply) > 128-10) {
+				o_stream_nsend(output, str_data(reply),
+					       str_len(reply));
+				str_truncate(reply, 0);
+			}
+			str_printfa(reply, "(%u)", msgs[i]);
+		}
+		str_append_c(reply, ')');
+	}
+}
+
+static int imap_thread_orderedsubject(struct client_command_context *cmd,
+				      struct mail_search_args *search_args)
+{
+	static const enum mail_sort_type sort_program[] = {
+		MAIL_SORT_SUBJECT,
+		MAIL_SORT_DATE,
+		0
+	};
+	struct mailbox_transaction_context *trans;
+	struct mail_search_context *search_ctx;
+	struct mail *mail;
+	string_t *prev_subject, *reply;
+	const char *subject, *base_subject;
+	pool_t pool;
+	ARRAY(struct orderedsubject_thread) threads;
+	const struct orderedsubject_thread *thread;
+	struct orderedsubject_thread *cur_thread = NULL;
+	uint32_t num;
+	bool reply_or_fw;
+	int ret, tz;
+
+	prev_subject = str_new(default_pool, 128);
+
+	/* first read all of the threads into memory */
+	pool = pool_alloconly_create("orderedsubject thread", 1024);
+	i_array_init(&threads, 128);
+	trans = mailbox_transaction_begin(cmd->client->mailbox, 0,
+					  imap_client_command_get_reason(cmd));
+	search_ctx = mailbox_search_init(trans, search_args, sort_program,
+					 0, NULL);
+	while (mailbox_search_next(search_ctx, &mail)) {
+		if (mail_get_first_header(mail, "Subject", &subject) <= 0)
+			subject = "";
+		T_BEGIN {
+			base_subject = imap_get_base_subject_cased(
+					pool_datastack_create(), subject,
+					&reply_or_fw);
+			if (strcmp(str_c(prev_subject), base_subject) != 0) {
+				/* thread changed */
+				cur_thread = NULL;
+			}
+			str_truncate(prev_subject, 0);
+			str_append(prev_subject, base_subject);
+		} T_END;
+
+		if (cur_thread == NULL) {
+			/* starting a new thread. get the first message's
+			   date */
+			cur_thread = array_append_space(&threads);
+			if (mail_get_date(mail, &cur_thread->timestamp,
+					  &tz) == 0 &&
+			    cur_thread->timestamp == 0) {
+				(void)mail_get_received_date(mail,
+					&cur_thread->timestamp);
+			}
+			p_array_init(&cur_thread->msgs, pool, 4);
+		}
+		num = cmd->uid ? mail->uid : mail->seq;
+		array_push_back(&cur_thread->msgs, &num);
+	}
+	str_free(&prev_subject);
+	ret = mailbox_search_deinit(&search_ctx);
+	(void)mailbox_transaction_commit(&trans);
+	if (ret < 0) {
+		array_free(&threads);
+		pool_unref(&pool);
+		return -1;
+	}
+
+	/* sort the threads by their first message's timestamp */
+	array_sort(&threads, orderedsubject_thread_cmp);
+
+	/* write the threads to client */
+	reply = t_str_new(128);
+	str_append(reply, "* THREAD ");
+	array_foreach(&threads, thread) {
+		imap_orderedsubject_thread_write(cmd->client->output,
+						 reply, thread);
+	}
+	str_append(reply, "\r\n");
+	o_stream_nsend(cmd->client->output, str_data(reply), str_len(reply));
+
+	array_free(&threads);
+	pool_unref(&pool);
+	return 0;
+}
+
+bool cmd_thread(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	enum mail_thread_type thread_type;
+	struct mail_search_args *sargs;
+	const struct imap_arg *args;
+	const char *charset, *str;
+	int ret;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	if (!imap_arg_get_astring(&args[0], &str) ||
+	    !imap_arg_get_astring(&args[1], &charset)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+	args += 2;
+
+	if (!mail_thread_type_parse(str, &thread_type)) {
+		client_send_command_error(cmd, "Unknown thread algorithm.");
+		return TRUE;
+	}
+
+	ret = imap_search_args_build(cmd, args, charset, &sargs);
+	if (ret <= 0)
+		return ret < 0;
+
+	if (thread_type != MAIL_THREAD_ORDEREDSUBJECT)
+		ret = imap_thread(cmd, sargs, thread_type);
+	else
+		ret = imap_thread_orderedsubject(cmd, sargs);
+	mail_search_args_unref(&sargs);
+	if (ret < 0) {
+		client_send_box_error(cmd, client->mailbox);
+		return TRUE;
+	}
+
+	return cmd_sync(cmd, MAILBOX_SYNC_FLAG_FAST |
+			(cmd->uid ? 0 : MAILBOX_SYNC_FLAG_NO_EXPUNGES),
+			0, "OK Thread completed.");
+}
diff --git a/src/imap/cmd-unselect.c b/src/imap/cmd-unselect.c
new file mode 100644
index 0000000..7f9f547
--- /dev/null
+++ b/src/imap/cmd-unselect.c
@@ -0,0 +1,18 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+
+bool cmd_unselect(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+
+	if (!client_verify_open_mailbox(cmd))
+		return TRUE;
+
+	i_assert(client->mailbox_change_lock == NULL);
+
+	imap_client_close_mailbox(client);
+	client_send_tagline(cmd, "OK Unselect completed.");
+	return TRUE;
+}
diff --git a/src/imap/cmd-unsubscribe.c b/src/imap/cmd-unsubscribe.c
new file mode 100644
index 0000000..1d23624
--- /dev/null
+++ b/src/imap/cmd-unsubscribe.c
@@ -0,0 +1,9 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+
+bool cmd_unsubscribe(struct client_command_context *cmd)
+{
+	return cmd_subscribe_full(cmd, FALSE);
+}
diff --git a/src/imap/cmd-urlfetch.c b/src/imap/cmd-urlfetch.c
new file mode 100644
index 0000000..6ea5ad5
--- /dev/null
+++ b/src/imap/cmd-urlfetch.c
@@ -0,0 +1,410 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "strfuncs.h"
+#include "str.h"
+#include "array.h"
+#include "net.h"
+#include "istream.h"
+#include "istream-sized.h"
+#include "ostream.h"
+#include "imap-url.h"
+#include "imap-quote.h"
+#include "imap-common.h"
+#include "imap-commands.h"
+#include "imap-urlauth.h"
+#include "imap-urlauth-fetch.h"
+
+struct cmd_urlfetch_context {
+	struct imap_urlauth_fetch *ufetch;
+	struct istream *input;
+
+	bool failed:1;
+	bool finished:1;
+	bool extended:1;
+	bool in_io_handler:1;
+};
+
+struct cmd_urlfetch_url {
+	const char *url;
+	
+	enum imap_urlauth_fetch_flags flags;
+};
+
+static void cmd_urlfetch_finish(struct client_command_context *cmd)
+{
+	struct cmd_urlfetch_context *ctx =
+		(struct cmd_urlfetch_context *)cmd->context;
+
+	if (ctx->finished)
+		return;
+	ctx->finished = TRUE;
+
+	i_stream_unref(&ctx->input);
+	if (ctx->ufetch != NULL)
+		imap_urlauth_fetch_deinit(&ctx->ufetch);
+
+	if (ctx->failed) {
+		if (cmd->client->output_cmd_lock == cmd) {
+			/* failed in the middle of a literal.
+			   we need to disconnect. */
+			cmd->client->output_cmd_lock = NULL;
+			client_disconnect(cmd->client, "URLFETCH failed");
+		} else {
+			client_send_internal_error(cmd);
+		}
+		return;
+	}
+
+	client_send_tagline(cmd, "OK URLFETCH completed.");
+}
+
+static bool cmd_urlfetch_cancel(struct client_command_context *cmd)
+{
+	struct cmd_urlfetch_context *ctx =
+		(struct cmd_urlfetch_context *)cmd->context;
+
+	if (!cmd->cancel)
+		return FALSE;
+
+	if (ctx->ufetch != NULL) {
+		e_debug(cmd->client->event,
+			"URLFETCH: Canceling command; "
+			"aborting URLAUTH fetch requests prematurely");
+		imap_urlauth_fetch_deinit(&ctx->ufetch);
+	}
+	return TRUE;
+}
+
+static int cmd_urlfetch_transfer_literal(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct cmd_urlfetch_context *ctx =
+		(struct cmd_urlfetch_context *)cmd->context;
+	enum ostream_send_istream_result res;
+	int ret;
+
+	/* are we in the middle of an urlfetch literal? */
+	if (ctx->input == NULL)
+		return 1;
+
+	/* flush output to client if buffer is filled above optimum */
+	if (o_stream_get_buffer_used_size(client->output) >=
+	    CLIENT_OUTPUT_OPTIMAL_SIZE) {
+		if ((ret = o_stream_flush(client->output)) <= 0)
+			return ret;
+	}
+
+	/* transfer literal to client */
+	o_stream_set_max_buffer_size(client->output, 0);
+	res = o_stream_send_istream(client->output, ctx->input);
+	o_stream_set_max_buffer_size(client->output, SIZE_MAX);
+
+	switch (res) {
+	case OSTREAM_SEND_ISTREAM_RESULT_FINISHED:
+		i_stream_unref(&ctx->input);
+		return 1;
+	case OSTREAM_SEND_ISTREAM_RESULT_WAIT_INPUT:
+		i_unreached();
+	case OSTREAM_SEND_ISTREAM_RESULT_WAIT_OUTPUT:
+		return 0;
+	case OSTREAM_SEND_ISTREAM_RESULT_ERROR_INPUT:
+		e_error(client->event, "read(%s) failed: %s (URLFETCH)",
+			i_stream_get_name(ctx->input),
+			i_stream_get_error(ctx->input));
+		client_disconnect(client, "URLFETCH failed");
+		return -1;
+	case OSTREAM_SEND_ISTREAM_RESULT_ERROR_OUTPUT:
+		/* client disconnected */
+		return -1;
+	}
+	i_unreached();
+}
+
+static bool cmd_urlfetch_continue(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct cmd_urlfetch_context *ctx =
+		(struct cmd_urlfetch_context *)cmd->context;
+	bool urls_pending;
+	int ret = 1;
+
+	if (cmd->cancel)
+		return cmd_urlfetch_cancel(cmd);
+
+	i_assert(client->output_cmd_lock == NULL ||
+		 client->output_cmd_lock == cmd);
+
+	/* finish a pending literal transfer */
+	ret = cmd_urlfetch_transfer_literal(cmd);
+	if (ret < 0) {
+		ctx->failed = TRUE;
+		cmd_urlfetch_finish(cmd);
+		return TRUE;
+	}
+	if (ret == 0) {
+		/* not finished; apparently output blocked again */
+		return FALSE;
+	}
+
+	if (ctx->extended)
+		client_send_line(client, ")");
+	else
+		client_send_line(client, "");
+	client->output_cmd_lock = NULL;
+
+	ctx->in_io_handler = TRUE;
+	urls_pending = imap_urlauth_fetch_continue(ctx->ufetch);
+	ctx->in_io_handler = FALSE;
+
+	if (urls_pending) {
+		/* waiting for imap urlauth service */
+		cmd->state = CLIENT_COMMAND_STATE_WAIT_EXTERNAL;
+		cmd->func = cmd_urlfetch_cancel;
+
+		/* retrieve next url */
+		return FALSE;
+	}
+
+	/* finished */
+	cmd_urlfetch_finish(cmd);
+	return TRUE;
+}
+
+static int cmd_urlfetch_url_success(struct client_command_context *cmd,
+				   struct imap_urlauth_fetch_reply *reply)
+{
+	struct cmd_urlfetch_context *ctx = cmd->context;
+	string_t *response = t_str_new(256);
+	int ret;
+
+	str_append(response, "* URLFETCH ");
+	imap_append_astring(response, reply->url);
+
+	if ((reply->flags & IMAP_URLAUTH_FETCH_FLAG_EXTENDED) == 0) {
+		/* simple */
+		ctx->extended = FALSE;
+
+		str_printfa(response, " {%"PRIuUOFF_T"}", reply->size);
+		client_send_line(cmd->client, str_c(response));
+		i_assert(reply->size == 0 || reply->input != NULL);
+	} else {
+		bool metadata = FALSE;
+
+		/* extended */
+		ctx->extended = TRUE;
+
+		str_append(response, " (");
+		if ((reply->flags & IMAP_URLAUTH_FETCH_FLAG_BODYPARTSTRUCTURE) != 0 &&
+		    reply->bodypartstruct != NULL) {
+			str_append(response, "BODYPARTSTRUCTURE (");
+			str_append(response, reply->bodypartstruct);
+			str_append_c(response, ')');
+			metadata = TRUE;
+		}
+		if ((reply->flags & IMAP_URLAUTH_FETCH_FLAG_BODY) != 0 ||
+		    (reply->flags & IMAP_URLAUTH_FETCH_FLAG_BINARY) != 0) {
+			if (metadata)
+				str_append_c(response, ' ');
+			if ((reply->flags & IMAP_URLAUTH_FETCH_FLAG_BODY) != 0) {
+				str_append(response, "BODY ");
+			} else {
+				str_append(response, "BINARY ");
+				if (reply->binary_has_nuls)
+					str_append_c(response, '~');
+			}
+			str_printfa(response, "{%"PRIuUOFF_T"}", reply->size);
+			i_assert(reply->size == 0 || reply->input != NULL);
+		} else {
+			str_append_c(response, ')');
+			ctx->extended = FALSE;
+		}
+
+		client_send_line(cmd->client, str_c(response));
+	}
+
+	if (reply->input != NULL) {
+		ctx->input = i_stream_create_sized(reply->input, reply->size);
+
+		ret = cmd_urlfetch_transfer_literal(cmd);
+		if (ret < 0) {
+			ctx->failed = TRUE;
+			return -1;
+		}
+		if (ret == 0) {
+			/* not finished; apparently output blocked */
+			cmd->state = CLIENT_COMMAND_STATE_WAIT_OUTPUT;
+			cmd->func = cmd_urlfetch_continue;
+			cmd->client->output_cmd_lock = cmd;
+			return 0;
+		}
+
+		if (ctx->extended)
+			client_send_line(cmd->client, ")");
+		else
+			client_send_line(cmd->client, "");
+	}
+	return 1;
+}
+
+static int
+cmd_urlfetch_url_callback(struct imap_urlauth_fetch_reply *reply,
+			  bool last, void *context)
+{
+	struct client_command_context *cmd = context;
+	struct client *client = cmd->client;
+	struct cmd_urlfetch_context *ctx = cmd->context;
+	bool in_io_handler = ctx->in_io_handler;
+	int ret;
+
+	if (!in_io_handler)
+		o_stream_cork(client->output);
+	if (reply == NULL) {
+		/* fatal failure */
+		ctx->failed = TRUE;
+		ret = -1;
+	} else if (reply->succeeded) {
+		/* URL fetch succeeded */
+		ret = cmd_urlfetch_url_success(cmd, reply);
+	} else {
+		/* URL fetch failed */
+		string_t *response = t_str_new(128);
+
+		str_append(response, "* URLFETCH ");
+		imap_append_astring(response, reply->url);
+		str_append(response, " NIL");
+		client_send_line(client, str_c(response));
+		if (reply->error != NULL) {
+			client_send_line(client, t_strdup_printf(
+				"* NO %s.", reply->error));
+		}
+		ret = 1;
+	}
+
+	if ((last && cmd->state == CLIENT_COMMAND_STATE_WAIT_EXTERNAL) ||
+	    ret < 0) {
+		cmd_urlfetch_finish(cmd);
+		client_command_free(&cmd);
+	}
+	if (!in_io_handler)
+		o_stream_uncork(client->output);
+	return ret;
+}
+
+static int
+cmd_urlfetch_parse_arg(struct client_command_context *cmd,
+		       const struct imap_arg *arg,
+		       struct cmd_urlfetch_url *ufurl_r)
+{
+	enum imap_urlauth_fetch_flags url_flags = 0;
+	const struct imap_arg *params;
+	const char *url_text;
+
+	if (imap_arg_get_list(arg, &params))
+		url_flags |= IMAP_URLAUTH_FETCH_FLAG_EXTENDED;
+	else
+		params = arg;
+
+	/* read url */
+	if (!imap_arg_get_astring(params++, &url_text)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return -1;
+	}
+	ufurl_r->url = t_strdup(url_text);
+	if (url_flags == 0)
+		return 0;
+
+	while (!IMAP_ARG_IS_EOL(params)) {
+		const char *fetch_param;
+
+		if (!imap_arg_get_atom(params++, &fetch_param)) {
+			client_send_command_error(cmd,
+				"Invalid URL fetch parameter.");
+			return -1;
+		}
+
+		if (strcasecmp(fetch_param, "BODY") == 0)
+			url_flags |= IMAP_URLAUTH_FETCH_FLAG_BODY;
+		else if (strcasecmp(fetch_param, "BINARY") == 0)
+			url_flags |= IMAP_URLAUTH_FETCH_FLAG_BINARY;
+		else if (strcasecmp(fetch_param, "BODYPARTSTRUCTURE") == 0)
+			url_flags |= IMAP_URLAUTH_FETCH_FLAG_BODYPARTSTRUCTURE;
+		else {
+			client_send_command_error(cmd,
+				t_strdup_printf("Unknown URL fetch parameter: %s",
+						fetch_param));
+			return -1;
+		}
+	}
+
+	if ((url_flags & IMAP_URLAUTH_FETCH_FLAG_BODY) != 0 &&
+	    (url_flags & IMAP_URLAUTH_FETCH_FLAG_BINARY) != 0) {
+		client_send_command_error(cmd,
+			"URL cannot have both BODY and BINARY fetch parameters.");
+		return -1;
+	}
+
+	if (url_flags == IMAP_URLAUTH_FETCH_FLAG_EXTENDED)
+		url_flags |= IMAP_URLAUTH_FETCH_FLAG_BODY;
+	ufurl_r->flags = url_flags;
+	return 0;
+}
+
+bool cmd_urlfetch(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct cmd_urlfetch_context *ctx;
+	ARRAY(struct cmd_urlfetch_url) urls;
+	const struct cmd_urlfetch_url *url;
+	const struct imap_arg *args;
+	struct cmd_urlfetch_url *ufurl;
+
+	if (client->urlauth_ctx == NULL) {
+		client_send_command_error(cmd, "URLAUTH disabled.");
+		return TRUE;
+	}
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	if (IMAP_ARG_IS_EOL(args)) {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+	
+	t_array_init(&urls, 32);
+
+	/* parse url arguments and group them per userid */
+	for (; !IMAP_ARG_IS_EOL(args); args++) {
+		ufurl = array_append_space(&urls);
+		if (cmd_urlfetch_parse_arg(cmd, args, ufurl) < 0)
+			return TRUE;
+	}
+	cmd->context = ctx = p_new(cmd->pool, struct cmd_urlfetch_context, 1);
+	cmd->func = cmd_urlfetch_cancel;
+	cmd->state = CLIENT_COMMAND_STATE_WAIT_INPUT;
+
+	ctx->ufetch = imap_urlauth_fetch_init(client->urlauth_ctx,
+					      cmd_urlfetch_url_callback, cmd);
+
+	ctx->in_io_handler = TRUE;
+	array_foreach(&urls, url) {
+		if (imap_urlauth_fetch_url(ctx->ufetch, url->url, url->flags) < 0) {
+			/* fatal error */
+			ctx->failed = TRUE;
+			break;
+		}
+	}
+	ctx->in_io_handler = FALSE;
+
+	if ((ctx->failed || !imap_urlauth_fetch_is_pending(ctx->ufetch))
+		&& cmd->client->output_cmd_lock != cmd) {
+		/* finished */
+		cmd_urlfetch_finish(cmd);
+		return TRUE;
+	}
+
+	if (cmd->client->output_cmd_lock != cmd)
+		cmd->state = CLIENT_COMMAND_STATE_WAIT_EXTERNAL;
+	return FALSE;	
+}
diff --git a/src/imap/cmd-x-cancel.c b/src/imap/cmd-x-cancel.c
new file mode 100644
index 0000000..3f49451
--- /dev/null
+++ b/src/imap/cmd-x-cancel.c
@@ -0,0 +1,28 @@
+/* Copyright (c) 2006-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-commands.h"
+
+bool cmd_x_cancel(struct client_command_context *cmd)
+{
+	struct client_command_context *cancel_cmd;
+	const char *tag;
+
+	/* <tag> */
+	if (!client_read_string_args(cmd, 1, &tag))
+		return FALSE;
+
+	cancel_cmd = cmd->client->command_queue;
+	for (; cancel_cmd != NULL; cancel_cmd = cancel_cmd->next) {
+		if (cancel_cmd->tag != NULL && cancel_cmd != cmd &&
+		    strcmp(cancel_cmd->tag, tag) == 0) {
+			client_command_cancel(&cancel_cmd);
+			client_send_tagline(cmd, "OK Command cancelled.");
+			return TRUE;
+		}
+	}
+
+	client_send_tagline(cmd, "NO Command tag not found.");
+	return TRUE;
+}
+
diff --git a/src/imap/cmd-x-state.c b/src/imap/cmd-x-state.c
new file mode 100644
index 0000000..8809998
--- /dev/null
+++ b/src/imap/cmd-x-state.c
@@ -0,0 +1,68 @@
+/* Copyright (c) 2015-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "base64.h"
+#include "str.h"
+#include "imap-commands.h"
+#include "imap-state.h"
+
+bool cmd_x_state(struct client_command_context *cmd)
+{
+	/* FIXME: state importing can cause unnecessarily large memory usage
+	   by specifying an old modseq, because the EXPUNGE/FETCH replies
+	   aren't currently sent asynchronously. so this command is disabled
+	   for now. */
+#if 0
+	const struct imap_arg *args;
+	const char *str, *error;
+	buffer_t *state, *state_encoded;
+	int ret;
+
+	if (!client_read_args(cmd, 0, 0, &args))
+		return FALSE;
+
+	state = buffer_create_dynamic(cmd->pool, 256);
+	if (imap_arg_get_astring(&args[0], &str)) {
+		if (cmd->client->mailbox != NULL) {
+			client_send_tagline(cmd,
+				"BAD Can't be used in SELECTED state");
+			return TRUE;
+		}
+		if (base64_decode(str, strlen(str), NULL, state) < 0)
+			ret = 0;
+		else {
+			ret = imap_state_import_external(cmd->client,
+				state->data, state->used, &error);
+		}
+		if (ret < 0) {
+			client_send_tagline(cmd, t_strdup_printf(
+				"NO Failed to restore state: %s", error));
+		} else if (ret == 0) {
+			client_send_tagline(cmd, t_strdup_printf(
+				"BAD Broken state: %s", error));
+		} else {
+			client_send_tagline(cmd, "OK State imported.");
+		}
+		return TRUE;
+	} else if (args[0].type == IMAP_ARG_EOL) {
+		if (!imap_state_export_external(cmd->client, state, &error)) {
+			client_send_tagline(cmd, t_strdup_printf(
+				"NO Can't save state: %s", error));
+			return TRUE;
+		}
+		state_encoded = buffer_create_dynamic(cmd->pool,
+				MAX_BASE64_ENCODED_SIZE(state->used)+10);
+		str_append(state_encoded, "* STATE ");
+		base64_encode(state->data, state->used, state_encoded);
+		client_send_line(cmd->client, str_c(state_encoded));
+		client_send_tagline(cmd, "OK State exported.");
+		return TRUE;
+	} else {
+		client_send_command_error(cmd, "Invalid arguments.");
+		return TRUE;
+	}
+#else
+	client_send_command_error(cmd, "Command is disabled for now.");
+	return TRUE;
+#endif
+}
diff --git a/src/imap/imap-client-hibernate.c b/src/imap/imap-client-hibernate.c
new file mode 100644
index 0000000..b29f500
--- /dev/null
+++ b/src/imap/imap-client-hibernate.c
@@ -0,0 +1,294 @@
+/* Copyright (c) 2014-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "fdpass.h"
+#include "net.h"
+#include "ostream.h"
+#include "write-full.h"
+#include "base64.h"
+#include "str.h"
+#include "strescape.h"
+#include "master-service.h"
+#include "mailbox-watch.h"
+#include "imap-state.h"
+#include "imap-client.h"
+
+#include <sys/stat.h>
+
+#define IMAP_HIBERNATE_SOCKET_NAME "imap-hibernate"
+#define IMAP_HIBERNATE_SEND_TIMEOUT_SECS 10
+#define IMAP_HIBERNATE_HANDSHAKE "VERSION\timap-hibernate\t1\t0\n"
+
+static int
+imap_hibernate_handshake(int fd, const char *path, const char **error_r)
+{
+	char buf[1024];
+	ssize_t ret;
+
+	if (write_full(fd, IMAP_HIBERNATE_HANDSHAKE,
+		       strlen(IMAP_HIBERNATE_HANDSHAKE)) < 0) {
+		*error_r = t_strdup_printf("write(%s) failed: %m", path);
+		return -1;
+	} else if ((ret = read(fd, buf, sizeof(buf)-1)) < 0) {
+		*error_r = t_strdup_printf("read(%s) failed: %m", path);
+		return -1;
+	} else if (ret > 0 && buf[ret-1] == '\n') {
+		buf[ret-1] = '\0';
+		if (version_string_verify(buf, "imap-hibernate", 1))
+			return 0;
+	} else {
+		buf[ret] = '\0';
+	}
+	*error_r = t_strdup_printf("%s sent invalid VERSION handshake: %s",
+				   path, buf);
+	return -1;
+}
+
+static void imap_hibernate_write_cmd(struct client *client, string_t *cmd,
+				     const buffer_t *state, int fd_notify)
+{
+	struct mail_user *user = client->user;
+	struct stat peer_st;
+	const char *tag;
+
+	tag = client->command_queue == NULL ? NULL : client->command_queue->tag;
+
+	str_append_tabescaped(cmd, user->username);
+	str_append_c(cmd, '\t');
+	str_append_tabescaped(cmd, user->set->mail_log_prefix);
+	str_printfa(cmd, "\tidle_notify_interval=%u",
+		    client->set->imap_idle_notify_interval);
+	if (fstat(client->fd_in, &peer_st) == 0) {
+		str_printfa(cmd, "\tpeer_dev_major=%lu\tpeer_dev_minor=%lu\tpeer_ino=%llu",
+			    (unsigned long)major(peer_st.st_dev),
+			    (unsigned long)minor(peer_st.st_dev),
+			    (unsigned long long)peer_st.st_ino);
+	}
+
+	str_append(cmd, "\tsession=");
+	str_append_tabescaped(cmd, user->session_id);
+	if (user->session_create_time != 0) {
+		str_printfa(cmd, "\tsession_created=%s",
+			    dec2str(user->session_create_time));
+	}
+	if (user->conn.local_ip != NULL)
+		str_printfa(cmd, "\tlip=%s", net_ip2addr(user->conn.local_ip));
+	if (user->conn.local_port != 0)
+		str_printfa(cmd, "\tlport=%u", user->conn.local_port);
+	if (user->conn.remote_ip != NULL)
+		str_printfa(cmd, "\trip=%s", net_ip2addr(user->conn.remote_ip));
+	if (user->conn.remote_port != 0)
+		str_printfa(cmd, "\trport=%u", user->conn.remote_port);
+	if (client->userdb_fields != NULL) {
+		string_t *userdb_fields = t_str_new(256);
+		unsigned int i;
+
+		for (i = 0; client->userdb_fields[i] != NULL; i++) {
+			if (i > 0)
+				str_append_c(userdb_fields, '\t');
+			str_append_tabescaped(userdb_fields, client->userdb_fields[i]);
+		}
+		str_append(cmd, "\tuserdb_fields=");
+		str_append_tabescaped(cmd, str_c(userdb_fields));
+	}
+	if (user->uid != (uid_t)-1)
+		str_printfa(cmd, "\tuid=%s", dec2str(user->uid));
+	if (user->gid != (gid_t)-1)
+		str_printfa(cmd, "\tgid=%s", dec2str(user->gid));
+	if (client->mailbox != NULL) {
+		str_append(cmd, "\tmailbox=");
+		str_append_tabescaped(cmd, mailbox_get_vname(client->mailbox));
+	}
+	if (tag != NULL) {
+		str_append(cmd, "\ttag=");
+		str_append_tabescaped(cmd, tag);
+	}
+	str_append(cmd, "\tstats=");
+	str_append_tabescaped(cmd, client_stats(client));
+	if (client->command_queue != NULL &&
+	    strcasecmp(client->command_queue->name, "IDLE") == 0)
+		str_append(cmd, "\tidle-cmd");
+	if (fd_notify != -1)
+		str_append(cmd, "\tnotify_fd");
+	str_append(cmd, "\tstate=");
+	base64_encode(state->data, state->used, cmd);
+	str_append_c(cmd, '\n');
+}
+
+static int
+imap_hibernate_process_send_cmd(int fd_socket, const char *path,
+				const string_t *cmd, int fd_client,
+				const char **error_r)
+{
+	ssize_t ret;
+
+	i_assert(fd_socket != -1);
+	i_assert(str_len(cmd) > 1);
+
+	if (imap_hibernate_handshake(fd_socket, path, error_r) < 0)
+		return -1;
+	if ((ret = fd_send(fd_socket, fd_client, str_data(cmd), 1)) < 0) {
+		*error_r = t_strdup_printf("fd_send(%s) failed: %m", path);
+		return -1;
+	}
+	i_assert(ret == 1);
+	if (write_full(fd_socket, str_data(cmd)+1, str_len(cmd)-1) < 0) {
+		*error_r = t_strdup_printf("write(%s) failed: %m", path);
+		return -1;
+	}
+	return 0;
+}
+
+static int
+imap_hibernate_process_read(int fd, const char *path, const char **error_r)
+{
+	char buf[1024];
+	ssize_t ret;
+
+	if ((ret = read(fd, buf, sizeof(buf)-1)) < 0) {
+		*error_r = t_strdup_printf("read(%s) failed: %m", path);
+		return -1;
+	} else if (ret == 0) {
+		*error_r = t_strdup_printf("%s disconnected", path);
+		return -1;
+	} else if (buf[0] != '+') {
+		buf[ret] = '\0';
+		*error_r = t_strdup_printf("%s returned failure: %s", path,
+			ret > 0 && buf[0] == '-' ? buf+1 : buf);
+		return -1;
+	} else {
+		return 0;
+	}
+}
+
+static int
+imap_hibernate_process_send(struct client *client, const buffer_t *state,
+			    int fd_notify, int *fd_r, const char **error_r)
+{
+	string_t *cmd = t_str_new(512);
+	const char *path;
+	ssize_t ret = 0;
+	int fd;
+
+	i_assert(state->used > 0);
+
+	*fd_r = -1;
+
+	path = t_strconcat(client->user->set->base_dir,
+			   "/"IMAP_HIBERNATE_SOCKET_NAME, NULL);
+	fd = net_connect_unix_with_retries(path, 1000);
+	if (fd == -1) {
+		*error_r = t_strdup_printf(
+			"net_connect_unix(%s) failed: %m", path);
+		return -1;
+	}
+	net_set_nonblock(fd, FALSE);
+
+	imap_hibernate_write_cmd(client, cmd, state, fd_notify);
+
+	alarm(IMAP_HIBERNATE_SEND_TIMEOUT_SECS);
+	if (imap_hibernate_process_send_cmd(fd, path, cmd, client->fd_in, error_r) < 0 ||
+	    imap_hibernate_process_read(fd, path, error_r) < 0)
+		ret = -1;
+	else if (fd_notify != -1) {
+		if ((ret = fd_send(fd, fd_notify, "\n", 1)) < 0)
+			*error_r = t_strdup_printf("fd_send(%s) failed: %m", path);
+		else
+			ret = imap_hibernate_process_read(fd, path, error_r);
+	}
+	alarm(0);
+	if (ret < 0) {
+		net_disconnect(fd);
+		return -1;
+	}
+	*fd_r = fd;
+	return 0;
+}
+
+bool imap_client_hibernate(struct client **_client, const char **reason_r)
+{
+	struct client *client = *_client;
+	buffer_t *state;
+	const char *error;
+	int ret, fd_notify = -1, fd_hibernate = -1;
+
+	*reason_r = NULL;
+
+	if (client->fd_in != client->fd_out) {
+		/* we won't try to hibernate stdio clients */
+		*reason_r = "stdio clients can't be hibernated";
+		return FALSE;
+	}
+	if (o_stream_get_buffer_used_size(client->output) > 0) {
+		/* wait until we've sent the pending output to client */
+		*reason_r = "output pending to client";
+		return FALSE;
+	}
+
+	struct event_passthrough *e =
+		event_create_passthrough(client->event)->
+		set_name("imap_client_hibernated");
+	if (client->mailbox != NULL)
+		e->add_str("mailbox", mailbox_get_vname(client->mailbox));
+
+	state = buffer_create_dynamic(default_pool, 1024);
+	ret = imap_state_export_internal(client, state, &error);
+	if (ret < 0) {
+		e->add_str("error", error);
+		e_error(e->event(), "Couldn't hibernate imap client: "
+			"Couldn't export state: %s (mailbox=%s)", error,
+			client->mailbox == NULL ? "" :
+			mailbox_get_vname(client->mailbox));
+		*reason_r = error;
+	} else if (ret == 0) {
+		e->add_str("error", error);
+		e_debug(e->event(), "Couldn't hibernate imap client: "
+			"Couldn't export state: %s (mailbox=%s)", error,
+			client->mailbox == NULL ? "" :
+			mailbox_get_vname(client->mailbox));
+		*reason_r = error;
+	}
+	if (ret > 0 && client->mailbox != NULL) {
+		fd_notify = mailbox_watch_extract_notify_fd(client->mailbox,
+							    &error);
+		if (fd_notify == -1) {
+			e->add_str("error", error);
+			e_debug(e->event(), "Couldn't hibernate imap client: "
+				"Couldn't extract notifications fd: %s",
+				error);
+			*reason_r = error;
+			ret = -1;
+		}
+	}
+	if (ret > 0) {
+		if (imap_hibernate_process_send(client, state, fd_notify,
+						&fd_hibernate, &error) < 0) {
+			e->add_str("error", error);
+			e_error(e->event(),
+				"Couldn't hibernate imap client: %s", error);
+			*reason_r = error;
+			ret = -1;
+		}
+	}
+	i_close_fd(&fd_notify);
+	if (ret > 0) {
+		/* hide the disconnect log message, because the client didn't
+		   actually log out */
+		e_debug(e->event(),
+			"Successfully hibernated imap client in mailbox %s",
+			client->mailbox == NULL ? "<none>" :
+			mailbox_get_vname(client->mailbox));
+		client->disconnected = TRUE;
+		client->hibernated = TRUE;
+		client_destroy(client, NULL);
+		*_client = NULL;
+	}
+	/* notify imap-hibernate that we're done by closing the connection.
+	   do this only after client is destroyed. this way imap-hibernate
+	   won't try to launch another imap process too early and cause
+	   problems (like sending duplicate session ID to stats process) */
+	if (fd_hibernate != -1)
+		net_disconnect(fd_hibernate);
+	buffer_free(&state);
+	return ret > 0;
+}
diff --git a/src/imap/imap-client.c b/src/imap/imap-client.c
new file mode 100644
index 0000000..b5418f6
--- /dev/null
+++ b/src/imap/imap-client.c
@@ -0,0 +1,1676 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "ioloop.h"
+#include "llist.h"
+#include "str.h"
+#include "hostpid.h"
+#include "net.h"
+#include "iostream.h"
+#include "iostream-rawlog.h"
+#include "istream.h"
+#include "istream-concat.h"
+#include "ostream.h"
+#include "time-util.h"
+#include "var-expand.h"
+#include "master-service.h"
+#include "imap-resp-code.h"
+#include "imap-util.h"
+#include "imap-urlauth.h"
+#include "mail-error.h"
+#include "mail-namespace.h"
+#include "mail-storage-service.h"
+#include "mail-autoexpunge.h"
+#include "imap-state.h"
+#include "imap-search.h"
+#include "imap-notify.h"
+#include "imap-commands.h"
+#include "imap-feature.h"
+
+#include <unistd.h>
+
+/* If the last command took longer than this to run, log statistics on
+   where the time was spent. */
+#define IMAP_CLIENT_DISCONNECT_LOG_STATS_CMD_MIN_RUNNING_MSECS 1000
+
+extern struct mail_storage_callbacks mail_storage_callbacks;
+extern struct imap_client_vfuncs imap_client_vfuncs;
+
+struct imap_module_register imap_module_register = { 0 };
+
+struct client *imap_clients = NULL;
+unsigned int imap_client_count = 0;
+
+unsigned int imap_feature_condstore = UINT_MAX;
+unsigned int imap_feature_qresync = UINT_MAX;
+
+static const char *client_command_state_names[CLIENT_COMMAND_STATE_DONE+1] = {
+	"wait-input",
+	"wait-output",
+	"wait-external",
+	"wait-unambiguity",
+	"wait-sync",
+	"done"
+};
+
+static void client_idle_timeout(struct client *client)
+{
+	if (client->output_cmd_lock == NULL)
+		client_send_line(client, "* BYE Disconnected for inactivity.");
+	client_destroy(client, t_strdup_printf(
+		"Inactivity - no input for %"PRIdTIME_T" secs",
+		ioloop_time - client->last_input));
+}
+
+static void client_init_urlauth(struct client *client)
+{
+	struct imap_urlauth_config config;
+
+	i_zero(&config);
+	config.url_host = client->set->imap_urlauth_host;
+	config.url_port = client->set->imap_urlauth_port;
+	config.socket_path = t_strconcat(client->user->set->base_dir,
+					 "/"IMAP_URLAUTH_SOCKET_NAME, NULL);
+	config.session_id = client->user->session_id;
+	config.access_user = client->user->username;
+	config.access_service = "imap";
+	config.access_anonymous = client->user->anonymous;
+
+	client->urlauth_ctx = imap_urlauth_init(client->user, &config);
+}
+
+static bool user_has_special_use_mailboxes(struct mail_user *user)
+{
+	struct mail_namespace_settings *ns_set;
+
+	/*
+	 * We have to iterate over namespace and mailbox *settings* since
+	 * the namespaces haven't been set up yet.  The namespaces haven't
+	 * been set up so that we don't hold up the OK response to LOGIN
+	 * when using slow lib-storage backends.
+	 */
+
+	/* no namespaces => no special use flags */
+	if (!array_is_created(&user->set->namespaces))
+		return FALSE;
+
+	array_foreach_elem(&user->set->namespaces, ns_set) {
+		struct mailbox_settings *box_set;
+
+		/* no mailboxes => no special use flags */
+		if (!array_is_created(&ns_set->mailboxes))
+			continue;
+
+		array_foreach_elem(&ns_set->mailboxes, box_set) {
+			if (box_set->special_use != NULL)
+				return TRUE;
+		}
+	}
+
+	return FALSE;
+}
+
+struct client *client_create(int fd_in, int fd_out,
+			     struct event *event, struct mail_user *user,
+			     struct mail_storage_service_user *service_user,
+			     const struct imap_settings *set,
+			     const struct smtp_submit_settings *smtp_set)
+{
+	const struct mail_storage_settings *mail_set;
+	struct client *client;
+	const char *ident;
+	pool_t pool;
+
+	/* always use nonblocking I/O */
+	net_set_nonblock(fd_in, TRUE);
+	net_set_nonblock(fd_out, TRUE);
+
+	pool = pool_alloconly_create("imap client", 2048);
+	client = p_new(pool, struct client, 1);
+	client->pool = pool;
+	client->v = imap_client_vfuncs;
+	client->event = event;
+	event_ref(client->event);
+	client->set = set;
+	client->smtp_set = smtp_set;
+	client->service_user = service_user;
+	client->fd_in = fd_in;
+	client->fd_out = fd_out;
+	client->input = i_stream_create_fd(fd_in,
+					   set->imap_max_line_length);
+	client->output = o_stream_create_fd(fd_out, SIZE_MAX);
+	o_stream_set_no_error_handling(client->output, TRUE);
+	i_stream_set_name(client->input, "<imap client>");
+	o_stream_set_name(client->output, "<imap client>");
+
+	o_stream_set_flush_callback(client->output, client_output, client);
+
+	p_array_init(&client->module_contexts, client->pool, 5);
+        client->last_input = ioloop_time;
+	client->to_idle = timeout_add(CLIENT_IDLE_TIMEOUT_MSECS,
+				      client_idle_timeout, client);
+
+	client->command_pool =
+		pool_alloconly_create(MEMPOOL_GROWING"client command", 1024*2);
+	client->user = user;
+	client->notify_count_changes = TRUE;
+	client->notify_flag_changes = TRUE;
+	p_array_init(&client->enabled_features, client->pool, 8);
+
+	client->capability_string =
+		str_new(client->pool, sizeof(CAPABILITY_STRING)+64);
+
+	if (*set->imap_capability == '\0')
+		str_append(client->capability_string, CAPABILITY_STRING);
+	else if (*set->imap_capability != '+') {
+		str_append(client->capability_string, set->imap_capability);
+	} else {
+		str_append(client->capability_string, CAPABILITY_STRING);
+		str_append_c(client->capability_string, ' ');
+		str_append(client->capability_string, set->imap_capability + 1);
+	}
+	if (client->set->imap_literal_minus)
+		client_add_capability(client, "LITERAL-");
+	else
+		client_add_capability(client, "LITERAL+");
+	if (user->fuzzy_search) {
+		/* Enable FUZZY capability only when it actually has
+		   a chance of working */
+		client_add_capability(client, "SEARCH=FUZZY");
+	}
+
+	mail_set = mail_user_set_get_storage_set(user);
+	if (mail_set->mailbox_list_index) {
+		/* NOTIFY is enabled only when mailbox list indexes are
+		   enabled, although even that doesn't necessarily guarantee
+		   it always */
+		client_add_capability(client, "NOTIFY");
+	}
+
+	if (*set->imap_urlauth_host != '\0' &&
+	    *mail_set->mail_attribute_dict != '\0') {
+		/* Enable URLAUTH capability only when dict is
+		   configured correctly */
+		client_init_urlauth(client);
+		client_add_capability(client, "URLAUTH");
+		client_add_capability(client, "URLAUTH=BINARY");
+	}
+	if (set->imap_metadata && *mail_set->mail_attribute_dict != '\0')
+		client_add_capability(client, "METADATA");
+	if (user_has_special_use_mailboxes(user)) {
+		/* Advertise SPECIAL-USE only if there are actually some
+		   SPECIAL-USE flags in mailbox configuration. */
+		client_add_capability(client, "SPECIAL-USE");
+	}
+
+	ident = mail_user_get_anvil_userip_ident(client->user);
+	if (ident != NULL) {
+		master_service_anvil_send(master_service, t_strconcat(
+			"CONNECT\t", my_pid, "\timap/", ident, "\n", NULL));
+		client->anvil_sent = TRUE;
+	}
+
+	imap_client_count++;
+	DLLIST_PREPEND(&imap_clients, client);
+	if (hook_client_created != NULL)
+		hook_client_created(&client);
+
+	imap_refresh_proctitle();
+	return client;
+}
+
+void client_create_finish_io(struct client *client)
+{
+	if (client->set->rawlog_dir[0] != '\0') {
+		(void)iostream_rawlog_create(client->set->rawlog_dir,
+					     &client->input, &client->output);
+	}
+	client->io = io_add_istream(client->input, client_input, client);
+}
+
+int client_create_finish(struct client *client, const char **error_r)
+{
+	if (mail_namespaces_init(client->user, error_r) < 0)
+		return -1;
+	mail_namespaces_set_storage_callbacks(client->user->namespaces,
+					      &mail_storage_callbacks, client);
+	client->v.init(client);
+	return 0;
+}
+
+void client_add_istream_prefix(struct client *client,
+			       const unsigned char *data, size_t size)
+{
+	i_assert(client->io == NULL);
+
+	struct istream *inputs[] = {
+		i_stream_create_copy_from_data(data, size),
+		client->input,
+		NULL
+	};
+	client->input = i_stream_create_concat(inputs);
+	i_stream_copy_fd(client->input, inputs[1]);
+	i_stream_unref(&inputs[0]);
+	i_stream_unref(&inputs[1]);
+
+	i_stream_set_input_pending(client->input, TRUE);
+}
+
+static void client_default_init(struct client *client ATTR_UNUSED)
+{
+	/* nothing */
+}
+
+void client_command_cancel(struct client_command_context **_cmd)
+{
+	struct client_command_context *cmd = *_cmd;
+	bool cmd_ret;
+
+	switch (cmd->state) {
+	case CLIENT_COMMAND_STATE_WAIT_INPUT:
+		/* a bit kludgy check: cancel command only if it has context
+		   set. currently only append command matches this check. all
+		   other commands haven't even started the processing yet. */
+		if (cmd->context == NULL)
+			break;
+		/* fall through */
+	case CLIENT_COMMAND_STATE_WAIT_EXTERNAL:
+	case CLIENT_COMMAND_STATE_WAIT_OUTPUT:
+		cmd->cancel = TRUE;
+		break;
+	case CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY:
+	case CLIENT_COMMAND_STATE_WAIT_SYNC:
+		/* commands haven't started yet */
+		break;
+	case CLIENT_COMMAND_STATE_DONE:
+		i_unreached();
+	}
+
+	cmd_ret = !cmd->cancel || cmd->func == NULL ? TRUE :
+		command_exec(cmd);
+	if (!cmd_ret) {
+		if (cmd->client->output->closed)
+			i_panic("command didn't cancel itself: %s", cmd->name);
+	} else {
+		client_command_free(*_cmd != NULL ? _cmd : &cmd);
+	}
+}
+
+const char *client_stats(struct client *client)
+{
+	const struct var_expand_table logout_tab[] = {
+		{ 'i', dec2str(i_stream_get_absolute_offset(client->input)), "input" },
+		{ 'o', dec2str(client->output->offset), "output" },
+		{ '\0', client->user->session_id, "session" },
+		{ '\0', dec2str(client->fetch_hdr_count), "fetch_hdr_count" },
+		{ '\0', dec2str(client->fetch_hdr_bytes), "fetch_hdr_bytes" },
+		{ '\0', dec2str(client->fetch_body_count), "fetch_body_count" },
+		{ '\0', dec2str(client->fetch_body_bytes), "fetch_body_bytes" },
+		{ '\0', dec2str(client->deleted_count), "deleted" },
+		{ '\0', dec2str(client->expunged_count), "expunged" },
+		{ '\0', dec2str(client->trashed_count), "trashed" },
+		{ '\0', dec2str(client->autoexpunged_count), "autoexpunged" },
+		{ '\0', dec2str(client->append_count), "appended" },
+		{ '\0', NULL, NULL }
+	};
+	const struct var_expand_table *user_tab =
+		mail_user_var_expand_table(client->user);
+	const struct var_expand_table *tab =
+		t_var_expand_merge_tables(logout_tab, user_tab);
+	string_t *str;
+	const char *error;
+
+	str = t_str_new(128);
+	if (var_expand_with_funcs(str, client->set->imap_logout_format,
+				  tab, mail_user_var_expand_func_table,
+				  client->user, &error) < 0) {
+		e_error(client->event,
+			"Failed to expand imap_logout_format=%s: %s",
+			client->set->imap_logout_format, error);
+	}
+	return str_c(str);
+}
+
+void client_destroy(struct client *client, const char *reason)
+{
+	client->v.destroy(client, reason);
+}
+
+static void
+client_command_stats_append(string_t *str,
+			    const struct client_command_stats *stats,
+			    const char *wait_condition,
+			    size_t buffered_size)
+{
+	uint64_t ioloop_wait_usecs;
+	unsigned int msecs_in_ioloop;
+
+	ioloop_wait_usecs = io_loop_get_wait_usecs(current_ioloop);
+	msecs_in_ioloop = (ioloop_wait_usecs -
+		stats->start_ioloop_wait_usecs + 999) / 1000;
+	str_printfa(str, "running for %d.%03d + waiting ",
+		    (int)((stats->running_usecs+999)/1000 / 1000),
+		    (int)((stats->running_usecs+999)/1000 % 1000));
+	if (wait_condition[0] != '\0')
+		str_printfa(str, "%s ", wait_condition);
+	str_printfa(str, "for %d.%03d secs",
+		    msecs_in_ioloop / 1000, msecs_in_ioloop % 1000);
+	if (stats->lock_wait_usecs > 0) {
+		int lock_wait_msecs = (stats->lock_wait_usecs+999)/1000;
+		str_printfa(str, ", %d.%03d in locks",
+			    lock_wait_msecs/1000, lock_wait_msecs%1000);
+	}
+	str_printfa(str, ", %"PRIu64" B in + %"PRIu64,
+		    stats->bytes_in, stats->bytes_out);
+	if (buffered_size > 0)
+		str_printfa(str, "+%zu", buffered_size);
+	str_append(str, " B out");
+}
+
+static const char *client_get_last_command_status(struct client *client)
+{
+	if (client->logged_out)
+		return "";
+	if (client->last_cmd_name == NULL)
+		return " (No commands sent)";
+
+	/* client disconnected without sending LOGOUT. if the last command
+	   took over 1 second to run, log it. */
+	const struct client_command_stats *stats = &client->last_cmd_stats;
+
+	string_t *str = t_str_new(128);
+	int last_run_secs = timeval_diff_msecs(&ioloop_timeval,
+					       &stats->last_run_timeval);
+	str_printfa(str, " (%s finished %d.%03d secs ago",
+		    client->last_cmd_name, last_run_secs/1000,
+		    last_run_secs%1000);
+
+	if (timeval_diff_msecs(&stats->last_run_timeval, &stats->start_time) >=
+	    IMAP_CLIENT_DISCONNECT_LOG_STATS_CMD_MIN_RUNNING_MSECS) {
+		str_append(str, " - ");
+		client_command_stats_append(str, stats, "", 0);
+	}
+	str_append_c(str, ')');
+	return str_c(str);
+}
+
+static const char *client_get_commands_status(struct client *client)
+{
+	struct client_command_context *cmd, *last_cmd = NULL;
+	struct client_command_stats all_stats;
+	string_t *str;
+	enum io_condition cond;
+	const char *cond_str;
+
+	if (client->command_queue == NULL)
+		return client_get_last_command_status(client);
+
+	i_zero(&all_stats);
+	str = t_str_new(128);
+	str_append(str, " (");
+	for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {
+		if (cmd->name == NULL) {
+			/* (parts of a) tag were received, but not yet
+			   the command name */
+			continue;
+		}
+		str_append(str, cmd->name);
+		if (cmd->next != NULL)
+			str_append_c(str, ',');
+		all_stats.running_usecs += cmd->stats.running_usecs;
+		all_stats.lock_wait_usecs += cmd->stats.lock_wait_usecs;
+		all_stats.bytes_in += cmd->stats.bytes_in;
+		all_stats.bytes_out += cmd->stats.bytes_out;
+		last_cmd = cmd;
+	}
+	if (last_cmd == NULL)
+		return client_get_last_command_status(client);
+
+	cond = io_loop_find_fd_conditions(current_ioloop, client->fd_out);
+	if ((cond & (IO_READ | IO_WRITE)) == (IO_READ | IO_WRITE))
+		cond_str = "input/output";
+	else if ((cond & IO_READ) != 0)
+		cond_str = "input";
+	else if ((cond & IO_WRITE) != 0)
+		cond_str = "output";
+	else
+		cond_str = "nothing";
+
+	all_stats.start_ioloop_wait_usecs =
+		last_cmd->stats.start_ioloop_wait_usecs;
+	str_append_c(str, ' ');
+	client_command_stats_append(str, &all_stats, cond_str,
+		o_stream_get_buffer_used_size(client->output));
+	str_printfa(str, ", state=%s)",
+		    client_command_state_names[last_cmd->state]);
+	return str_c(str);
+}
+
+static void client_log_disconnect(struct client *client, const char *reason)
+{
+	e_info(client->event, "Disconnected: %s %s", reason, client_stats(client));
+}
+
+static void client_default_destroy(struct client *client, const char *reason)
+{
+	struct client_command_context *cmd;
+
+	i_assert(!client->destroyed);
+	client->destroyed = TRUE;
+	client->disconnected = TRUE;
+
+	if (client->disconnect_reason != NULL)
+		reason = client->disconnect_reason;
+	if (reason == NULL)
+		reason = t_strconcat(
+			io_stream_get_disconnect_reason(client->input,
+							client->output),
+			client_get_commands_status(client), NULL);
+
+	i_stream_close(client->input);
+	o_stream_close(client->output);
+
+	/* finish off all the queued commands. */
+	if (client->output_cmd_lock != NULL)
+		client_command_cancel(&client->output_cmd_lock);
+	while (client->command_queue != NULL) {
+		cmd = client->command_queue;
+		client_command_cancel(&cmd);
+	}
+	/* handle the input_lock command last. it might have been waiting on
+	   other queued commands (although we probably should just drop the
+	   command at that point since it hasn't started running. but this may
+	   change in future). */
+	if (client->input_lock != NULL)
+		client_command_cancel(&client->input_lock);
+
+	if (client->notify_ctx != NULL)
+		imap_notify_deinit(&client->notify_ctx);
+	if (client->urlauth_ctx != NULL)
+		imap_urlauth_deinit(&client->urlauth_ctx);
+	/* Keep mailbox closing close to last, so anything that could
+	   potentially have transactions open will close them first. */
+	if (client->mailbox != NULL)
+		imap_client_close_mailbox(client);
+	if (client->anvil_sent) {
+		master_service_anvil_send(master_service, t_strconcat(
+			"DISCONNECT\t", my_pid, "\timap/",
+			mail_user_get_anvil_userip_ident(client->user),
+			"\n", NULL));
+	}
+
+	if (client->free_parser != NULL)
+		imap_parser_unref(&client->free_parser);
+	io_remove(&client->io);
+	timeout_remove(&client->to_idle_output);
+	timeout_remove(&client->to_idle);
+
+	/* i/ostreams are already closed at this stage, so fd can be closed */
+	fd_close_maybe_stdio(&client->fd_in, &client->fd_out);
+
+	/* Autoexpunging might run for a long time. Disconnect the client
+	   before it starts, and refresh proctitle so it's clear that it's
+	   doing autoexpunging. We've also sent DISCONNECT to anvil already,
+	   because this is background work and shouldn't really be counted
+	   as an active IMAP session for the user.
+
+	   Don't autoexpunge if the client is hibernated - it shouldn't be any
+	   different from the non-hibernating IDLE case. For frequent
+	   hibernations it could also be doing unnecessarily much work. */
+	imap_refresh_proctitle();
+	if (!client->hibernated) {
+		client->autoexpunged_count = mail_user_autoexpunge(client->user);
+		client_log_disconnect(client, reason);
+	}
+	mail_user_deinit(&client->user);
+
+	/* free the i/ostreams after mail_user_unref(), which could trigger
+	   mail_storage_callbacks notifications that write to the ostream. */
+	i_stream_destroy(&client->input);
+	o_stream_destroy(&client->output);
+
+	if (array_is_created(&client->search_saved_uidset))
+		array_free(&client->search_saved_uidset);
+	if (array_is_created(&client->search_updates))
+		array_free(&client->search_updates);
+	pool_unref(&client->command_pool);
+	mail_storage_service_user_unref(&client->service_user);
+
+	imap_client_count--;
+	DLLIST_REMOVE(&imap_clients, client);
+
+	event_unref(&client->event);
+	i_free(client->last_cmd_name);
+	pool_unref(&client->pool);
+
+	master_service_client_connection_destroyed(master_service);
+	imap_refresh_proctitle();
+}
+
+static void client_destroy_timeout(struct client *client)
+{
+	client_destroy(client, NULL);
+}
+
+void client_disconnect(struct client *client, const char *reason)
+{
+	if (client->disconnected)
+		return;
+
+	client->disconnected = TRUE;
+	client->disconnect_reason = p_strdup(client->pool, reason);
+	/* Finish the ostream. With IMAP COMPRESS this sends the EOF marker. */
+	(void)o_stream_finish(client->output);
+	o_stream_uncork(client->output);
+
+	i_stream_close(client->input);
+	o_stream_close(client->output);
+
+	timeout_remove(&client->to_idle);
+	client->to_idle = timeout_add(0, client_destroy_timeout, client);
+}
+
+void client_disconnect_with_error(struct client *client,
+				  const char *client_error)
+{
+	client_send_line(client, t_strconcat("* BYE ", client_error, NULL));
+	client_disconnect(client, client_error);
+}
+
+void client_add_capability(struct client *client, const char *capability)
+{
+	/* require a single capability at a time (feels cleaner) */
+	i_assert(strchr(capability, ' ') == NULL);
+
+	if (client->set->imap_capability[0] != '\0' &&
+	    client->set->imap_capability[0] != '+') {
+		/* explicit capability - don't change it */
+		return;
+	}
+	str_append_c(client->capability_string, ' ');
+	str_append(client->capability_string, capability);
+}
+
+void client_send_line(struct client *client, const char *data)
+{
+	(void)client_send_line_next(client, data);
+}
+
+int client_send_line_next(struct client *client, const char *data)
+{
+	struct const_iovec iov[2];
+
+	if (client->output->closed)
+		return -1;
+
+	iov[0].iov_base = data;
+	iov[0].iov_len = strlen(data);
+	iov[1].iov_base = "\r\n";
+	iov[1].iov_len = 2;
+
+	if (o_stream_sendv(client->output, iov, 2) < 0)
+		return -1;
+	client->last_output = ioloop_time;
+
+	if (o_stream_get_buffer_used_size(client->output) >=
+	    CLIENT_OUTPUT_OPTIMAL_SIZE) {
+		/* buffer full, try flushing */
+		return o_stream_flush(client->output);
+	}
+	return 1;
+}
+
+static void
+client_cmd_append_timing_stats(struct client_command_context *cmd,
+			       string_t *str)
+{
+	unsigned int msecs_in_cmd, msecs_in_ioloop;
+	uint64_t ioloop_wait_usecs;
+	unsigned int msecs_since_cmd;
+
+	if (cmd->stats.start_time.tv_sec == 0)
+		return;
+	command_stats_flush(cmd);
+
+	ioloop_wait_usecs = io_loop_get_wait_usecs(current_ioloop);
+	msecs_in_cmd = (cmd->stats.running_usecs + 999) / 1000;
+	msecs_in_ioloop = (ioloop_wait_usecs -
+			   cmd->stats.start_ioloop_wait_usecs + 999) / 1000;
+	msecs_since_cmd = timeval_diff_msecs(&ioloop_timeval,
+					     &cmd->stats.last_run_timeval);
+
+	if (str_data(str)[str_len(str)-1] == '.')
+		str_truncate(str, str_len(str)-1);
+	str_printfa(str, " (%d.%03d + %d.%03d ",
+		    msecs_in_cmd / 1000, msecs_in_cmd % 1000,
+		    msecs_in_ioloop / 1000, msecs_in_ioloop % 1000);
+	if (msecs_since_cmd > 0) {
+		str_printfa(str, "+ %d.%03d ",
+			    msecs_since_cmd / 1000, msecs_since_cmd % 1000);
+	}
+	str_append(str, "secs).");
+}
+
+void client_send_tagline(struct client_command_context *cmd, const char *data)
+{
+	cmd->client->v.send_tagline(cmd, data);
+}
+
+static void
+client_default_send_tagline(struct client_command_context *cmd, const char *data)
+{
+	struct client *client = cmd->client;
+	const char *tag = cmd->tag;
+
+	if (client->output->closed || cmd->cancel)
+		return;
+
+	i_assert(!cmd->tagline_sent);
+	cmd->tagline_sent = TRUE;
+	cmd->tagline_reply = p_strdup(cmd->pool, data);
+
+	if (tag == NULL || *tag == '\0')
+		tag = "*";
+
+	T_BEGIN {
+		string_t *str = t_str_new(256);
+		str_printfa(str, "%s %s", tag, data);
+		client_cmd_append_timing_stats(cmd, str);
+		str_append(str, "\r\n");
+		o_stream_nsend(client->output, str_data(str), str_len(str));
+	} T_END;
+
+	client->last_output = ioloop_time;
+}
+
+static int
+client_default_sync_notify_more(struct imap_sync_context *ctx ATTR_UNUSED)
+{
+	return 1;
+}
+
+void client_send_command_error(struct client_command_context *cmd,
+			       const char *client_error)
+{
+	struct client *client = cmd->client;
+	const char *error, *cmd_name;
+	enum imap_parser_error parse_error;
+
+	if (client_error == NULL) {
+		client_error = imap_parser_get_error(cmd->parser, &parse_error);
+		switch (parse_error) {
+		case IMAP_PARSE_ERROR_NONE:
+			i_unreached();
+		case IMAP_PARSE_ERROR_LITERAL_TOO_BIG:
+			client_disconnect_with_error(client, client_error);
+			return;
+		default:
+			break;
+		}
+	}
+
+	if (cmd->tag == NULL)
+		error = t_strconcat("BAD Error in IMAP tag: ", client_error, NULL);
+	else if (cmd->name == NULL)
+		error = t_strconcat("BAD Error in IMAP command: ", client_error, NULL);
+	else {
+		cmd_name = t_str_ucase(cmd->name);
+		error = t_strconcat("BAD Error in IMAP command ",
+				    cmd_name, ": ", client_error, NULL);
+	}
+
+	client_send_tagline(cmd, error);
+
+	if (++client->bad_counter >= CLIENT_MAX_BAD_COMMANDS) {
+		client_disconnect_with_error(client,
+			"Too many invalid IMAP commands.");
+	}
+
+	cmd->param_error = TRUE;
+	/* client_read_args() failures rely on this being set, so that the
+	   command processing is stopped even while command function returns
+	   FALSE. */
+	cmd->state = CLIENT_COMMAND_STATE_DONE;
+}
+
+void client_send_internal_error(struct client_command_context *cmd)
+{
+	client_send_tagline(cmd,
+		t_strflocaltime("NO "MAIL_ERRSTR_CRITICAL_MSG_STAMP, ioloop_time));
+}
+
+bool client_read_args(struct client_command_context *cmd, unsigned int count,
+		      unsigned int flags, const struct imap_arg **args_r)
+{
+	int ret;
+
+	i_assert(count <= INT_MAX);
+
+	ret = imap_parser_read_args(cmd->parser, count, flags, args_r);
+	if (ret >= (int)count) {
+		/* all parameters read successfully */
+		i_assert(cmd->client->input_lock == NULL ||
+			 cmd->client->input_lock == cmd);
+
+		client_args_finished(cmd, *args_r);
+		cmd->client->input_lock = NULL;
+		return TRUE;
+	} else if (ret == -2) {
+		/* need more data */
+		if (cmd->client->input->closed) {
+			/* disconnected */
+			cmd->state = CLIENT_COMMAND_STATE_DONE;
+		}
+		return FALSE;
+	} else {
+		/* error, or missing arguments */
+		client_send_command_error(cmd, ret < 0 ? NULL :
+					  "Missing arguments");
+		return FALSE;
+	}
+}
+
+bool client_read_string_args(struct client_command_context *cmd,
+			     unsigned int count, ...)
+{
+	const struct imap_arg *imap_args;
+	va_list va;
+	const char *str;
+	unsigned int i;
+
+	if (!client_read_args(cmd, count, 0, &imap_args))
+		return FALSE;
+
+	va_start(va, count);
+	for (i = 0; i < count; i++) {
+		const char **ret = va_arg(va, const char **);
+
+		if (IMAP_ARG_IS_EOL(&imap_args[i])) {
+			client_send_command_error(cmd, "Missing arguments.");
+			break;
+		}
+
+		if (!imap_arg_get_astring(&imap_args[i], &str)) {
+			client_send_command_error(cmd, "Invalid arguments.");
+			break;
+		}
+
+		if (ret != NULL)
+			*ret = str;
+	}
+	va_end(va);
+
+	return i == count;
+}
+
+void client_args_finished(struct client_command_context *cmd,
+			  const struct imap_arg *args)
+{
+	string_t *str = t_str_new(256);
+
+	if (cmd->args != NULL && cmd->args[0] != '\0') {
+		str_append(str, cmd->args);
+		str_append_c(str, ' ');
+	}
+	imap_write_args(str, args);
+	cmd->args = p_strdup(cmd->pool, str_c(str));
+	event_add_str(cmd->event, "cmd_args", cmd->args);
+
+	str_truncate(str, 0);
+	if (cmd->human_args != NULL && cmd->human_args[0] != '\0') {
+		str_append(str, cmd->human_args);
+		str_append_c(str, ' ');
+	}
+	imap_write_args_for_human(str, args);
+	cmd->human_args = p_strdup(cmd->pool, str_c(str));
+	event_add_str(cmd->event, "cmd_human_args", cmd->human_args);
+}
+
+static struct client_command_context *
+client_command_find_with_flags(struct client_command_context *new_cmd,
+			       enum command_flags flags,
+			       enum client_command_state max_state)
+{
+	struct client_command_context *cmd;
+
+	cmd = new_cmd->client->command_queue;
+	for (; cmd != NULL; cmd = cmd->next) {
+		/* The tagline_sent check is a bit kludgy here. Plugins may
+		   hook into sync_notify_more() and send the tagline before
+		   finishing the command. During this stage the state was been
+		   dropped from _WAIT_SYNC to _WAIT_OUTPUT, so the <= max_state
+		   check doesn't work correctly here. (Perhaps we should add
+		   a new _WAIT_SYNC_OUTPUT?) */
+		if (cmd->state <= max_state && !cmd->tagline_sent &&
+		    cmd != new_cmd && (cmd->cmd_flags & flags) != 0)
+			return cmd;
+	}
+	return NULL;
+}
+
+static bool client_command_is_ambiguous(struct client_command_context *cmd)
+{
+	enum command_flags flags;
+	enum client_command_state max_state =
+		CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY;
+	bool broken_client = FALSE;
+
+	if ((cmd->cmd_flags & COMMAND_FLAG_REQUIRES_SYNC) != 0 &&
+	    !imap_sync_is_allowed(cmd->client))
+		return TRUE;
+
+	if (cmd->search_save_result_used) {
+		/* if there are pending commands that update the search
+		   save result, wait */
+		struct client_command_context *old_cmd = cmd->next;
+
+		for (; old_cmd != NULL; old_cmd = old_cmd->next) {
+			if (old_cmd->search_save_result)
+				return TRUE;
+		}
+	}
+
+	if ((cmd->cmd_flags & COMMAND_FLAG_BREAKS_MAILBOX) ==
+	    COMMAND_FLAG_BREAKS_MAILBOX) {
+		/* there must be no other command running that uses the
+		   selected mailbox */
+		flags = COMMAND_FLAG_USES_MAILBOX;
+		max_state = CLIENT_COMMAND_STATE_DONE;
+	} else if ((cmd->cmd_flags & COMMAND_FLAG_USES_SEQS) != 0) {
+		/* no existing command must be breaking sequences */
+		flags = COMMAND_FLAG_BREAKS_SEQS;
+		broken_client = TRUE;
+	} else if ((cmd->cmd_flags & COMMAND_FLAG_BREAKS_SEQS) != 0) {
+		/* if existing command uses sequences, we'll have to block */
+		flags = COMMAND_FLAG_USES_SEQS;
+	} else {
+		return FALSE;
+	}
+
+	if (client_command_find_with_flags(cmd, flags, max_state) == NULL) {
+		if (cmd->client->syncing) {
+			/* don't do anything until syncing is finished */
+			return TRUE;
+		}
+		if (cmd->client->mailbox_change_lock != NULL &&
+		    cmd->client->mailbox_change_lock != cmd) {
+			/* don't do anything until mailbox is fully
+			   opened/closed */
+			return TRUE;
+		}
+		return FALSE;
+	}
+
+	if (broken_client) {
+		client_send_line(cmd->client,
+				 "* BAD ["IMAP_RESP_CODE_CLIENTBUG"] "
+				 "Command pipelining results in ambiguity.");
+	}
+
+	return TRUE;
+}
+
+struct client_command_context *client_command_alloc(struct client *client)
+{
+	struct client_command_context *cmd;
+
+	cmd = p_new(client->command_pool, struct client_command_context, 1);
+	cmd->client = client;
+	cmd->pool = client->command_pool;
+	cmd->global_event = event_create(client->event);
+	cmd->event = event_create(cmd->global_event);
+	cmd->stats.start_time = ioloop_timeval;
+	cmd->stats.last_run_timeval = ioloop_timeval;
+	cmd->stats.start_ioloop_wait_usecs =
+		io_loop_get_wait_usecs(current_ioloop);
+	p_array_init(&cmd->module_contexts, cmd->pool, 5);
+
+	DLLIST_PREPEND(&client->command_queue, cmd);
+	client->command_queue_size++;
+
+	imap_client_notify_command_allocated(client);
+	return cmd;
+}
+
+void client_command_init_finished(struct client_command_context *cmd)
+{
+	event_add_str(cmd->event, "cmd_tag", cmd->tag);
+	/* use "unknown" until we checked that the command name is known/valid */
+	event_add_str(cmd->event, "cmd_name", "unknown");
+	/* the actual command name received from client - as-is */
+	event_add_str(cmd->event, "cmd_input_name", cmd->name);
+}
+
+static struct client_command_context *
+client_command_new(struct client *client)
+{
+	struct client_command_context *cmd;
+
+	cmd = client_command_alloc(client);
+	if (client->free_parser != NULL) {
+		cmd->parser = client->free_parser;
+		client->free_parser = NULL;
+	} else {
+		cmd->parser =
+			imap_parser_create(client->input, client->output,
+					   client->set->imap_max_line_length);
+		if (client->set->imap_literal_minus)
+			imap_parser_enable_literal_minus(cmd->parser);
+	}
+	return cmd;
+}
+
+void client_add_missing_io(struct client *client)
+{
+	if (client->io == NULL && !client->disconnected)
+		client->io = io_add_istream(client->input, client_input, client);
+}
+
+void client_command_free(struct client_command_context **_cmd)
+{
+	struct client_command_context *cmd = *_cmd;
+	struct client *client = cmd->client;
+	enum client_command_state state = cmd->state;
+
+	*_cmd = NULL;
+
+	i_assert(!cmd->executing);
+	i_assert(client->output_cmd_lock == NULL);
+
+	/* reset input idle time because command output might have taken a
+	   long time and we don't want to disconnect client immediately then */
+	client->last_input = ioloop_time;
+	timeout_reset(client->to_idle);
+
+	if (cmd->cancel) {
+		cmd->cancel = FALSE;
+		client_send_tagline(cmd, "NO Command cancelled.");
+	}
+
+	i_free(client->last_cmd_name);
+	client->last_cmd_name = i_strdup(cmd->name);
+	client->last_cmd_stats = cmd->stats;
+
+	if (!cmd->param_error)
+		client->bad_counter = 0;
+
+	if (client->input_lock == cmd)
+		client->input_lock = NULL;
+	if (client->mailbox_change_lock == cmd)
+		client->mailbox_change_lock = NULL;
+
+	event_set_name(cmd->event, "imap_command_finished");
+	if (cmd->tagline_reply != NULL) {
+		event_add_str(cmd->event, "tagged_reply_state",
+			      t_strcut(cmd->tagline_reply, ' '));
+		event_add_str(cmd->event, "tagged_reply", cmd->tagline_reply);
+	}
+	event_add_timeval(cmd->event, "last_run_time",
+			  &cmd->stats.last_run_timeval);
+	event_add_int(cmd->event, "running_usecs", cmd->stats.running_usecs);
+	event_add_int(cmd->event, "lock_wait_usecs", cmd->stats.lock_wait_usecs);
+	event_add_int(cmd->event, "bytes_in", cmd->stats.bytes_in);
+	event_add_int(cmd->event, "bytes_out", cmd->stats.bytes_out);
+
+	e_debug(cmd->event, "Command finished: %s %s", cmd->name,
+		cmd->human_args != NULL ? cmd->human_args : "");
+	event_unref(&cmd->event);
+	event_unref(&cmd->global_event);
+
+	if (cmd->parser != NULL) {
+		if (client->free_parser == NULL) {
+			imap_parser_reset(cmd->parser);
+			client->free_parser = cmd->parser;
+		} else {
+			imap_parser_unref(&cmd->parser);
+		}
+	}
+
+	client->command_queue_size--;
+	DLLIST_REMOVE(&client->command_queue, cmd);
+	cmd = NULL;
+
+	if (client->command_queue == NULL) {
+		/* no commands left in the queue, we can clear the pool */
+		p_clear(client->command_pool);
+		timeout_remove(&client->to_idle_output);
+	}
+	imap_client_notify_command_freed(client);
+	imap_refresh_proctitle();
+
+	/* if command finished from external event, check input for more
+	   unhandled commands since we may not be executing from client_input
+	   or client_output. */
+	if (state == CLIENT_COMMAND_STATE_WAIT_EXTERNAL &&
+	    !client->disconnected) {
+		client_add_missing_io(client);
+		io_set_pending(client->io);
+	}
+}
+
+static void client_check_command_hangs(struct client *client)
+{
+	struct client_command_context *cmd;
+	unsigned int unfinished_count = 0;
+	bool have_wait_unfinished = FALSE;
+
+	for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {
+		switch (cmd->state) {
+		case CLIENT_COMMAND_STATE_WAIT_INPUT:
+			/* We need to be reading input for this command.
+			   However, if there is already an output lock for
+			   another command we'll wait for it to finish first.
+			   This is needed because if there are any literals
+			   we'd need to send "+ OK" responses. */
+			i_assert(client->io != NULL ||
+				 (client->output_cmd_lock != NULL &&
+				  client->output_cmd_lock != client->input_lock));
+			unfinished_count++;
+			break;
+		case CLIENT_COMMAND_STATE_WAIT_OUTPUT:
+			i_assert((io_loop_find_fd_conditions(current_ioloop, client->fd_out) & IO_WRITE) != 0);
+			unfinished_count++;
+			break;
+		case CLIENT_COMMAND_STATE_WAIT_EXTERNAL:
+			unfinished_count++;
+			break;
+		case CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY:
+			have_wait_unfinished = TRUE;
+			break;
+		case CLIENT_COMMAND_STATE_WAIT_SYNC:
+			if ((io_loop_find_fd_conditions(current_ioloop, client->fd_out) & IO_WRITE) == 0)
+				have_wait_unfinished = TRUE;
+			else {
+				/* we have an output callback, which will be
+				   called soon and it'll run cmd_sync_delayed().
+				   FIXME: is this actually wanted? */
+			}
+			break;
+		case CLIENT_COMMAND_STATE_DONE:
+			i_unreached();
+		}
+	}
+	i_assert(!have_wait_unfinished || unfinished_count > 0);
+}
+
+static bool client_remove_pending_unambiguity(struct client *client)
+{
+	if (client->input_lock != NULL) {
+		/* there's a command that has locked the input */
+		struct client_command_context *cmd = client->input_lock;
+
+		if (cmd->state != CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY)
+			return TRUE;
+
+		/* the command is waiting for existing ambiguity causing
+		   commands to finish. */
+		if (client_command_is_ambiguous(cmd)) {
+			/* we could be waiting for existing sync to finish */
+			if (!cmd_sync_delayed(client))
+				return FALSE;
+			if (client_command_is_ambiguous(cmd))
+				return FALSE;
+		}
+		cmd->state = CLIENT_COMMAND_STATE_WAIT_INPUT;
+	}
+	return TRUE;
+}
+
+void client_continue_pending_input(struct client *client)
+{
+	i_assert(!client->handling_input);
+
+	if (client->disconnected) {
+		client_destroy(client, NULL);
+		return;
+	}
+
+	/* this function is called at the end of I/O callbacks (and only there).
+	   fix up the command states and verify that they're correct. */
+	while (client_remove_pending_unambiguity(client)) {
+		client_add_missing_io(client);
+
+		/* if there's unread data in buffer, handle it. */
+		if (i_stream_get_data_size(client->input) == 0 ||
+		    client->disconnected)
+			break;
+
+		struct ostream *output = client->output;
+		o_stream_ref(output);
+		o_stream_cork(output);
+		bool ret = client_handle_input(client);
+		o_stream_uncork(output);
+		o_stream_unref(&output);
+		if (!ret)
+			break;
+	}
+	if (client->input->closed || client->output->closed)
+		client_destroy(client, NULL);
+	else
+		client_check_command_hangs(client);
+}
+
+/* Skip incoming data until newline is found,
+   returns TRUE if newline was found. */
+static bool client_skip_line(struct client *client)
+{
+	const unsigned char *data;
+	size_t i, data_size;
+
+	data = i_stream_get_data(client->input, &data_size);
+
+	for (i = 0; i < data_size; i++) {
+		if (data[i] == '\n') {
+			client->input_skip_line = FALSE;
+			i++;
+			break;
+		}
+	}
+
+	i_stream_skip(client->input, i);
+	return !client->input_skip_line;
+}
+
+static void client_idle_output_timeout(struct client *client)
+{
+	client_destroy(client, t_strdup_printf(
+		"Client has not read server output for for %"PRIdTIME_T" secs",
+		ioloop_time - client->last_output));
+}
+
+bool client_handle_unfinished_cmd(struct client_command_context *cmd)
+{
+	if (cmd->state == CLIENT_COMMAND_STATE_WAIT_INPUT) {
+		/* need more input */
+		return FALSE;
+	}
+	if (cmd->state != CLIENT_COMMAND_STATE_WAIT_OUTPUT) {
+		/* waiting for something */
+		if (cmd->state == CLIENT_COMMAND_STATE_WAIT_SYNC) {
+			/* this is mainly for APPEND. */
+			client_add_missing_io(cmd->client);
+		}
+		return TRUE;
+	}
+
+	/* output is blocking, we can execute more commands */
+	o_stream_set_flush_pending(cmd->client->output, TRUE);
+	if (cmd->client->to_idle_output == NULL) {
+		/* disconnect sooner if client isn't reading our output */
+		cmd->client->to_idle_output =
+			timeout_add(CLIENT_OUTPUT_TIMEOUT_MSECS,
+				    client_idle_output_timeout, cmd->client);
+	}
+	return TRUE;
+}
+
+static void
+client_command_failed_early(struct client_command_context **_cmd,
+			    const char *error)
+{
+	struct client_command_context *cmd = *_cmd;
+
+	/* ignore the rest of this line */
+	cmd->client->input_skip_line = TRUE;
+
+	io_loop_time_refresh();
+	command_stats_start(cmd);
+	client_send_command_error(cmd, error);
+	cmd->param_error = TRUE;
+	client_command_free(_cmd);
+}
+
+static bool client_command_input(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	struct command *command;
+	const char *tag, *name;
+	int ret;
+
+        if (cmd->func != NULL) {
+		/* command is being executed - continue it */
+		if (command_exec(cmd)) {
+			/* command execution was finished */
+			client_command_free(&cmd);
+			client_add_missing_io(client);
+			return TRUE;
+		}
+
+		return client_handle_unfinished_cmd(cmd);
+	}
+
+	if (cmd->tag == NULL) {
+		ret = imap_parser_read_tag(cmd->parser, &tag);
+		if (ret == 0)
+			return FALSE; /* need more data */
+		if (ret < 0) {
+			client_command_failed_early(&cmd, "Invalid tag.");
+			return TRUE;
+		}
+		cmd->tag = p_strdup(cmd->pool, tag);
+	}
+
+	if (cmd->name == NULL) {
+		ret = imap_parser_read_command_name(cmd->parser, &name);
+		if (ret == 0)
+			return FALSE; /* need more data */
+		if (ret < 0) {
+			client_command_failed_early(&cmd, "Invalid command name.");
+			return TRUE;
+		}
+
+		/* UID commands are a special case. better to handle them
+		   here. */
+		if (!cmd->uid && strcasecmp(name, "UID") == 0) {
+			cmd->uid = TRUE;
+			return client_command_input(cmd);
+		}
+		cmd->name = !cmd->uid ? p_strdup(cmd->pool, name) :
+			p_strconcat(cmd->pool, "UID ", name, NULL);
+		client_command_init_finished(cmd);
+		imap_refresh_proctitle();
+	}
+
+	client->input_skip_line = TRUE;
+
+	if (cmd->name[0] == '\0') {
+		/* command not given - cmd->func is already NULL. */
+	} else if ((command = command_find(cmd->name)) != NULL) {
+		cmd->func = command->func;
+		cmd->cmd_flags = command->flags;
+		/* valid command - overwrite the "unknown" string set earlier */
+		event_add_str(cmd->global_event, "cmd_name", command->name);
+		event_strlist_append(cmd->global_event, "reason_code",
+			event_reason_code_prefix("imap", "cmd_", command->name));
+		event_add_str(cmd->event, "cmd_name", command->name);
+		if (client_command_is_ambiguous(cmd)) {
+			/* do nothing until existing commands are finished */
+			i_assert(cmd->state == CLIENT_COMMAND_STATE_WAIT_INPUT);
+			cmd->state = CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY;
+			io_remove(&client->io);
+			return FALSE;
+		}
+	}
+
+	if (cmd->func == NULL) {
+		/* unknown command */
+		client_command_failed_early(&cmd, "Unknown command.");
+		return TRUE;
+	} else {
+		i_assert(!client->disconnected);
+
+		return client_command_input(cmd);
+	}
+}
+
+static bool client_handle_next_command(struct client *client, bool *remove_io_r)
+{
+	*remove_io_r = FALSE;
+
+	if (client->input_lock != NULL) {
+		if (client->input_lock->state ==
+		    CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY ||
+		    /* we can't send literal "+ OK" replies if output is
+		       locked by another command. */
+		    (client->output_cmd_lock != NULL &&
+		     client->output_cmd_lock != client->input_lock)) {
+			*remove_io_r = TRUE;
+			return FALSE;
+		}
+		return client_command_input(client->input_lock);
+	}
+
+	if (client->input_skip_line) {
+		/* first eat the previous command line */
+		if (!client_skip_line(client))
+			return FALSE;
+		client->input_skip_line = FALSE;
+	}
+
+	/* don't bother creating a new client command before there's at least
+	   some input */
+	if (i_stream_get_data_size(client->input) == 0)
+		return FALSE;
+
+	/* beginning a new command */
+	if (client->command_queue_size >= CLIENT_COMMAND_QUEUE_MAX_SIZE ||
+	    client->output_cmd_lock != NULL) {
+		/* wait for some of the commands to finish */
+		*remove_io_r = TRUE;
+		return FALSE;
+	}
+
+	client->input_lock = client_command_new(client);
+	return client_command_input(client->input_lock);
+}
+
+bool client_handle_input(struct client *client)
+{
+	bool ret, remove_io, handled_commands = FALSE;
+
+	i_assert(o_stream_is_corked(client->output) ||
+		 client->output->stream_errno != 0);
+	i_assert(!client->disconnected);
+
+	client->handling_input = TRUE;
+	do {
+		T_BEGIN {
+			ret = client_handle_next_command(client, &remove_io);
+		} T_END;
+		if (ret)
+			handled_commands = TRUE;
+	} while (ret && !client->disconnected && client->io != NULL);
+	client->handling_input = FALSE;
+
+	if (remove_io)
+		io_remove(&client->io);
+	else
+		client_add_missing_io(client);
+	if (!handled_commands)
+		return FALSE;
+
+	if (client->input_lock == NULL) {
+		/* finished handling all commands. sync them all at once now. */
+		cmd_sync_delayed(client);
+	} else if (client->input_lock->state == CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY) {
+		/* the command may be waiting for previous command to sync. */
+		cmd_sync_delayed(client);
+	}
+	return TRUE;
+}
+
+void client_input(struct client *client)
+{
+	struct client_command_context *cmd;
+	struct ostream *output = client->output;
+	ssize_t bytes;
+
+	i_assert(client->io != NULL);
+
+	client->last_input = ioloop_time;
+	timeout_reset(client->to_idle);
+
+	bytes = i_stream_read(client->input);
+	if (bytes == -1) {
+		/* disconnected */
+		client_destroy(client, NULL);
+		return;
+	}
+
+	o_stream_ref(output);
+	o_stream_cork(output);
+	if (!client_handle_input(client) && bytes == -2) {
+		/* parameter word is longer than max. input buffer size.
+		   this is most likely an error, so skip the new data
+		   until newline is found. */
+		client->input_skip_line = TRUE;
+
+		cmd = client->input_lock != NULL ? client->input_lock :
+			client_command_new(client);
+		cmd->param_error = TRUE;
+		client_send_command_error(cmd, "Too long argument.");
+		client_command_free(&cmd);
+	}
+	o_stream_uncork(output);
+	o_stream_unref(&output);
+	imap_refresh_proctitle();
+
+	client_continue_pending_input(client);
+}
+
+static void client_output_cmd(struct client_command_context *cmd)
+{
+	bool finished;
+
+	/* continue processing command */
+	finished = command_exec(cmd);
+
+	if (!finished)
+		(void)client_handle_unfinished_cmd(cmd);
+	else {
+		/* command execution was finished */
+		client_command_free(&cmd);
+	}
+}
+
+static void client_output_commands(struct client *client)
+{
+	struct client_command_context *cmd;
+
+	/* mark all commands non-executed */
+	for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next)
+		cmd->temp_executed = FALSE;
+
+	if (client->output_cmd_lock != NULL) {
+		client->output_cmd_lock->temp_executed = TRUE;
+		client_output_cmd(client->output_cmd_lock);
+	}
+	while (client->output_cmd_lock == NULL) {
+		/* go through the entire commands list every time in case
+		   multiple commands were freed. temp_executed keeps track of
+		   which messages we've called so far */
+		cmd = client->command_queue;
+		for (; cmd != NULL; cmd = cmd->next) {
+			if (!cmd->temp_executed &&
+			    cmd->state == CLIENT_COMMAND_STATE_WAIT_OUTPUT) {
+				cmd->temp_executed = TRUE;
+				client_output_cmd(cmd);
+				break;
+			}
+		}
+		if (cmd == NULL) {
+			/* all commands executed */
+			break;
+		}
+	}
+}
+
+int client_output(struct client *client)
+{
+	int ret;
+
+	i_assert(!client->destroyed);
+
+	client->last_output = ioloop_time;
+	timeout_reset(client->to_idle);
+	if (client->to_idle_output != NULL)
+		timeout_reset(client->to_idle_output);
+
+	if ((ret = o_stream_flush(client->output)) < 0) {
+		client_destroy(client, NULL);
+		return 1;
+	}
+
+	client_output_commands(client);
+	(void)cmd_sync_delayed(client);
+
+	imap_refresh_proctitle_delayed();
+	if (client->output->closed)
+		client_destroy(client, NULL);
+	else {
+		/* corking is added automatically by ostream-file. we need to
+		   uncork here before client_check_command_hangs() is called,
+		   because otherwise it can assert-crash due to ioloop not
+		   having IO_WRITE callback set for the ostream. */
+		o_stream_uncork(client->output);
+		client_continue_pending_input(client);
+	}
+	return ret;
+}
+
+bool client_handle_search_save_ambiguity(struct client_command_context *cmd)
+{
+	struct client_command_context *old_cmd = cmd->next;
+
+	/* search only commands that were added before this command
+	   (commands are prepended to the queue, so they're after ourself) */
+	for (; old_cmd != NULL; old_cmd = old_cmd->next) {
+		if (old_cmd->search_save_result)
+			break;
+	}
+	if (old_cmd == NULL)
+		return FALSE;
+
+	/* ambiguity, wait until it's over */
+	i_assert(cmd->state == CLIENT_COMMAND_STATE_WAIT_INPUT);
+	cmd->client->input_lock = cmd;
+	cmd->state = CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY;
+	cmd->search_save_result_used = TRUE;
+	io_remove(&cmd->client->io);
+	return TRUE;
+}
+
+void client_enable(struct client *client, unsigned int feature_idx)
+{
+	if (client_has_enabled(client, feature_idx))
+		return;
+
+	const struct imap_feature *feat = imap_feature_idx(feature_idx);
+	feat->callback(client);
+	/* set after the callback, so the callback can see what features were
+	   previously set */
+	bool value = TRUE;
+	array_idx_set(&client->enabled_features, feature_idx, &value);
+}
+
+bool client_has_enabled(struct client *client, unsigned int feature_idx)
+{
+	if (feature_idx >= array_count(&client->enabled_features))
+		return FALSE;
+	const bool *featurep =
+		array_idx(&client->enabled_features, feature_idx);
+	return *featurep;
+}
+
+static void imap_client_enable_condstore(struct client *client)
+{
+	struct mailbox_status status;
+	int ret;
+
+	if (client->mailbox == NULL)
+		return;
+
+	if ((client_enabled_mailbox_features(client) & MAILBOX_FEATURE_CONDSTORE) != 0)
+		return;
+
+	ret = mailbox_enable(client->mailbox, MAILBOX_FEATURE_CONDSTORE);
+	if (ret == 0) {
+		/* CONDSTORE being enabled while mailbox is selected.
+		   Notify client of the latest HIGHESTMODSEQ. */
+		ret = mailbox_get_status(client->mailbox,
+					 STATUS_HIGHESTMODSEQ, &status);
+		if (ret == 0) {
+			client_send_line(client, t_strdup_printf(
+				"* OK [HIGHESTMODSEQ %"PRIu64"] Highest",
+				status.highest_modseq));
+		}
+	}
+	if (ret < 0) {
+		client_send_untagged_storage_error(client,
+			mailbox_get_storage(client->mailbox));
+	}
+}
+
+static void imap_client_enable_qresync(struct client *client)
+{
+	/* enable also CONDSTORE */
+	client_enable(client, imap_feature_condstore);
+}
+
+enum mailbox_feature client_enabled_mailbox_features(struct client *client)
+{
+	enum mailbox_feature mailbox_features = 0;
+	const struct imap_feature *feature;
+	const bool *client_enabled;
+	unsigned int count;
+
+	client_enabled = array_get(&client->enabled_features, &count);
+	for (unsigned int idx = 0; idx < count; idx++) {
+		if (client_enabled[idx]) {
+			feature = imap_feature_idx(idx);
+			mailbox_features |= feature->mailbox_features;
+		}
+	}
+	return mailbox_features;
+}
+
+const char *const *client_enabled_features(struct client *client)
+{
+	ARRAY_TYPE(const_string) feature_strings;
+	const struct imap_feature *feature;
+	const bool *client_enabled;
+	unsigned int count;
+
+	t_array_init(&feature_strings, 8);
+	client_enabled = array_get(&client->enabled_features, &count);
+	for (unsigned int idx = 0; idx < count; idx++) {
+		if (client_enabled[idx]) {
+			feature = imap_feature_idx(idx);
+			array_push_back(&feature_strings, &feature->feature);
+		}
+	}
+	array_append_zero(&feature_strings);
+	return array_front(&feature_strings);
+}
+
+struct imap_search_update *
+client_search_update_lookup(struct client *client, const char *tag,
+			    unsigned int *idx_r)
+{
+	struct imap_search_update *updates;
+	unsigned int i, count;
+
+	if (!array_is_created(&client->search_updates))
+		return NULL;
+
+	updates = array_get_modifiable(&client->search_updates, &count);
+	for (i = 0; i < count; i++) {
+		if (strcmp(updates[i].tag, tag) == 0) {
+			*idx_r = i;
+			return &updates[i];
+		}
+	}
+	return NULL;
+}
+
+void client_search_updates_free(struct client *client)
+{
+	struct imap_search_update *update;
+
+	if (!array_is_created(&client->search_updates))
+		return;
+
+	array_foreach_modifiable(&client->search_updates, update)
+		imap_search_update_free(update);
+	array_clear(&client->search_updates);
+}
+
+void clients_init(void)
+{
+	imap_feature_condstore =
+		imap_feature_register("CONDSTORE", MAILBOX_FEATURE_CONDSTORE,
+				      imap_client_enable_condstore);
+	imap_feature_qresync =
+		imap_feature_register("QRESYNC", MAILBOX_FEATURE_CONDSTORE,
+				      imap_client_enable_qresync);
+}
+
+void clients_destroy_all(void)
+{
+	while (imap_clients != NULL) {
+		mail_storage_service_io_activate_user(imap_clients->service_user);
+		client_send_line(imap_clients, "* BYE Server shutting down.");
+		client_destroy(imap_clients, "Server shutting down.");
+	}
+}
+
+struct imap_client_vfuncs imap_client_vfuncs = {
+	.init = client_default_init,
+	.destroy = client_default_destroy,
+
+	.send_tagline = client_default_send_tagline,
+	.sync_notify_more = client_default_sync_notify_more,
+
+	.state_export = imap_state_export_base,
+	.state_import = imap_state_import_base,
+};
diff --git a/src/imap/imap-client.h b/src/imap/imap-client.h
new file mode 100644
index 0000000..a307955
--- /dev/null
+++ b/src/imap/imap-client.h
@@ -0,0 +1,361 @@
+#ifndef IMAP_CLIENT_H
+#define IMAP_CLIENT_H
+
+#include "imap-commands.h"
+#include "message-size.h"
+
+#define CLIENT_COMMAND_QUEUE_MAX_SIZE 4
+/* Maximum number of CONTEXT=SEARCH UPDATEs. Clients probably won't need more
+   than a few, so this is mainly to avoid more or less accidental pointless
+   resource usage. */
+#define CLIENT_MAX_SEARCH_UPDATES 10
+
+struct client;
+struct mail_storage;
+struct mail_storage_service_ctx;
+struct lda_settings;
+struct imap_parser;
+struct imap_arg;
+struct imap_urlauth_context;
+
+struct mailbox_keywords {
+	/* All keyword names. The array itself exists in mail_index.
+	   Keywords are currently only appended, they're never removed. */
+	const ARRAY_TYPE(keywords) *names;
+	/* Number of keywords announced to client via FLAGS/PERMANENTFLAGS.
+	   This relies on keywords not being removed while mailbox is
+	   selected. */
+	unsigned int announce_count;
+};
+
+struct imap_search_update {
+	char *tag;
+	struct mail_search_result *result;
+	bool return_uids;
+
+	pool_t fetch_pool;
+	struct imap_fetch_context *fetch_ctx;
+};
+
+enum client_command_state {
+	/* Waiting for more input */
+	CLIENT_COMMAND_STATE_WAIT_INPUT,
+	/* Waiting to be able to send more output */
+	CLIENT_COMMAND_STATE_WAIT_OUTPUT,
+	/* Waiting for external interaction */
+	CLIENT_COMMAND_STATE_WAIT_EXTERNAL,
+	/* Wait for other commands to finish execution */
+	CLIENT_COMMAND_STATE_WAIT_UNAMBIGUITY,
+	/* Waiting for other commands to finish so we can sync */
+	CLIENT_COMMAND_STATE_WAIT_SYNC,
+	/* Command is finished */
+	CLIENT_COMMAND_STATE_DONE
+};
+
+struct client_command_stats {
+	/* time when command handling was started - typically this is after
+	   reading all the parameters. */
+	struct timeval start_time;
+	/* time when command handling was last finished. this is before
+	   mailbox syncing is done. */
+	struct timeval last_run_timeval;
+	/* io_loop_get_wait_usecs()'s value when the command was started */
+	uint64_t start_ioloop_wait_usecs;
+	/* how many usecs this command itself has spent running */
+	uint64_t running_usecs;
+	/* how many usecs this command itself has spent waiting for locks */
+	uint64_t lock_wait_usecs;
+	/* how many bytes of client input/output command has used */
+	uint64_t bytes_in, bytes_out;
+};
+
+struct client_command_stats_start {
+	struct timeval timeval;
+	uint64_t lock_wait_usecs;
+	uint64_t bytes_in, bytes_out;
+};
+
+struct client_command_context {
+	struct client_command_context *prev, *next;
+	struct client *client;
+	struct event *event;
+	/* global_event is pushed to the global event stack while the command
+	   is running. It has only the minimal fields that are actually wanted
+	   to be in all the events while it's being run. */
+	struct event *global_event;
+
+	pool_t pool;
+	/* IMAP command tag */
+	const char *tag;
+	/* Name of this command */
+	const char *name;
+	/* Parameters for this command. These are generated from parsed IMAP
+	   arguments, so they may not be exactly the same as how client sent
+	   them. */
+	const char *args;
+	/* Parameters for this command generated with
+	   imap_write_args_for_human(), so it's suitable for logging. */
+	const char *human_args;
+	enum command_flags cmd_flags;
+	const char *tagline_reply;
+
+	command_func_t *func;
+	void *context;
+
+	/* Module-specific contexts. */
+	ARRAY(union imap_module_context *) module_contexts;
+
+	struct imap_parser *parser;
+	enum client_command_state state;
+	struct client_command_stats stats;
+	struct client_command_stats_start stats_start;
+
+	struct imap_client_sync_context *sync;
+
+	bool uid:1; /* used UID command */
+	bool cancel:1; /* command is wanted to be cancelled */
+	bool param_error:1;
+	bool search_save_result:1; /* search result is being updated */
+	bool search_save_result_used:1; /* command uses search save */
+	bool temp_executed:1; /* temporary execution state tracking */
+	bool tagline_sent:1;
+	bool executing:1;
+};
+
+struct imap_client_vfuncs {
+	/* Perform client initialization. This is called when client creation is
+	   finished completely. Particulary, at this point the namespaces are
+	   fully initialized, which is not the case for the client create hook.
+	 */
+	void (*init)(struct client *client);
+	/* Destroy the client.*/
+	void (*destroy)(struct client *client, const char *reason);
+
+	/* Send a tagged response line. */
+	void (*send_tagline)(struct client_command_context *cmd,
+			     const char *data);
+	/* Run "mailbox syncing". This can send any unsolicited untagged
+	   replies. Returns 1 = done, 0 = wait for more space in output buffer,
+	   -1 = failed. */
+	int (*sync_notify_more)(struct imap_sync_context *ctx);
+
+	/* Export client state into buffer. Returns 1 if ok, 0 if some state
+	   couldn't be preserved, -1 if temporary internal error occurred. */
+	int (*state_export)(struct client *client, bool internal,
+			    buffer_t *dest, const char **error_r);
+	/* Import a single block of client state from the given data. Returns
+	   number of bytes successfully imported from the block, or 0 if state
+	   is corrupted or contains unknown data (e.g. some plugin is no longer
+	   loaded), -1 if temporary internal error occurred. */
+	ssize_t (*state_import)(struct client *client, bool internal,
+				const unsigned char *data, size_t size,
+				const char **error_r);
+};
+
+struct client {
+	struct client *prev, *next;
+
+	struct imap_client_vfuncs v;
+	struct event *event;
+	const char *const *userdb_fields; /* for internal session saving/restoring */
+
+	int fd_in, fd_out;
+	struct io *io;
+	struct istream *input;
+	struct ostream *output;
+	struct timeout *to_idle, *to_idle_output, *to_delayed_input;
+
+	pool_t pool;
+	struct mail_storage_service_user *service_user;
+	const struct imap_settings *set;
+	const struct smtp_submit_settings *smtp_set;
+	string_t *capability_string;
+	const char *disconnect_reason;
+
+        struct mail_user *user;
+	struct mailbox *mailbox;
+        struct mailbox_keywords keywords;
+	unsigned int sync_counter;
+	uint32_t messages_count, recent_count, uidvalidity;
+	ARRAY(bool) enabled_features;
+
+	time_t last_input, last_output;
+	unsigned int bad_counter;
+
+	/* one parser is kept here to be used for new commands */
+	struct imap_parser *free_parser;
+	/* command_pool is cleared when the command queue gets empty */
+	pool_t command_pool;
+	/* New commands are always prepended to the queue */
+	struct client_command_context *command_queue;
+	unsigned int command_queue_size;
+
+	char *last_cmd_name;
+	struct client_command_stats last_cmd_stats;
+
+	uint64_t sync_last_full_modseq;
+	uint64_t highest_fetch_modseq;
+	ARRAY_TYPE(seq_range) fetch_failed_uids;
+
+	/* For imap_logout_format statistics: */
+	unsigned int fetch_hdr_count, fetch_body_count;
+	uint64_t fetch_hdr_bytes, fetch_body_bytes;
+	unsigned int deleted_count, expunged_count, trashed_count;
+	unsigned int autoexpunged_count, append_count;
+
+	/* SEARCHRES extension: Last saved SEARCH result */
+	ARRAY_TYPE(seq_range) search_saved_uidset;
+	/* SEARCH=CONTEXT extension: Searches that get updated */
+	ARRAY(struct imap_search_update) search_updates;
+	/* NOTIFY extension */
+	struct imap_notify_context *notify_ctx;
+	uint32_t notify_uidnext;
+
+	/* client input/output is locked by this command */
+	struct client_command_context *input_lock;
+	struct client_command_context *output_cmd_lock;
+	/* command changing the mailbox */
+	struct client_command_context *mailbox_change_lock;
+
+	/* IMAP URLAUTH context (RFC4467) */
+	struct imap_urlauth_context *urlauth_ctx;	
+
+	/* Module-specific contexts. */
+	ARRAY(union imap_module_context *) module_contexts;
+
+	/* syncing marks this TRUE when it sees \Deleted flags. this is by
+	   EXPUNGE for Outlook-workaround. */
+	bool sync_seen_deletes:1;
+	bool logged_out:1;
+	bool disconnected:1;
+	bool hibernated:1;
+	bool destroyed:1;
+	bool handling_input:1;
+	bool syncing:1;
+	bool id_logged:1;
+	bool mailbox_examined:1;
+	bool anvil_sent:1;
+	bool tls_compression:1;
+	bool input_skip_line:1; /* skip all the data until we've
+					   found a new line */
+	bool modseqs_sent_since_sync:1;
+	bool notify_immediate_expunges:1;
+	bool notify_count_changes:1;
+	bool notify_flag_changes:1;
+	bool nonpermanent_modseqs:1;
+	bool state_import_bad_idle_done:1;
+	bool state_import_idle_continue:1;
+};
+
+struct imap_module_register {
+	unsigned int id;
+};
+
+union imap_module_context {
+	struct imap_client_vfuncs super;
+	struct imap_module_register *reg;
+};
+extern struct imap_module_register imap_module_register;
+
+extern struct client *imap_clients;
+extern unsigned int imap_client_count;
+
+extern unsigned int imap_feature_condstore;
+extern unsigned int imap_feature_qresync;
+
+/* Create new client with specified input/output handles. socket specifies
+   if the handle is a socket. */
+struct client *client_create(int fd_in, int fd_out,
+			     struct event *event, struct mail_user *user,
+			     struct mail_storage_service_user *service_user,
+			     const struct imap_settings *set,
+			     const struct smtp_submit_settings *smtp_set);
+void client_create_finish_io(struct client *client);
+/* Finish creating the client. Returns 0 if ok, -1 if there's an error. */
+int client_create_finish(struct client *client, const char **error_r);
+void client_add_istream_prefix(struct client *client,
+			       const unsigned char *data, size_t size);
+void client_destroy(struct client *client, const char *reason) ATTR_NULL(2);
+
+/* Disconnect client connection */
+void client_disconnect(struct client *client, const char *reason);
+void client_disconnect_with_error(struct client *client,
+				  const char *client_error);
+
+/* Add the given capability to the CAPABILITY reply. If imap_capability setting
+   has an explicit capability, nothing is changed. */
+void client_add_capability(struct client *client, const char *capability);
+
+/* Send a line of data to client. */
+void client_send_line(struct client *client, const char *data);
+/* Send a line of data to client. Returns 1 if ok, 0 if buffer is getting full,
+   -1 if error. This should be used when you're (potentially) sending a lot of
+   lines to client. */
+int client_send_line_next(struct client *client, const char *data);
+/* Send line of data to client, prefixed with client->tag. You need to prefix
+   the data with "OK ", "NO " or "BAD ". */
+void client_send_tagline(struct client_command_context *cmd, const char *data);
+
+/* Send a BAD command reply to client via client_send_tagline(). If there have
+   been too many command errors, the client is disconnected. client_error may
+   be NULL, in which case the error is looked up from imap_parser. */
+void client_send_command_error(struct client_command_context *cmd,
+			       const char *client_error);
+
+/* Send a NO command reply with the default internal error message to client
+   via client_send_tagline(). */
+void client_send_internal_error(struct client_command_context *cmd);
+
+/* Read a number of arguments. Returns TRUE if everything was read or
+   FALSE if either needs more data or error occurred. */
+bool client_read_args(struct client_command_context *cmd, unsigned int count,
+		      unsigned int flags, const struct imap_arg **args_r);
+/* Reads a number of string arguments. ... is a list of pointers where to
+   store the arguments. */
+bool client_read_string_args(struct client_command_context *cmd,
+			     unsigned int count, ...);
+void client_args_finished(struct client_command_context *cmd,
+			  const struct imap_arg *args);
+
+/* SEARCHRES extension: Call if $ is being used/updated, returns TRUE if we
+   have to wait for an existing SEARCH SAVE to finish. */
+bool client_handle_search_save_ambiguity(struct client_command_context *cmd);
+
+void client_enable(struct client *client, unsigned int feature_idx);
+/* Returns TRUE if the given feature is enabled */
+bool client_has_enabled(struct client *client, unsigned int feature_idx);
+/* Returns mailbox features that are currently enabled. */
+enum mailbox_feature client_enabled_mailbox_features(struct client *client);
+/* Returns all enabled features as strings. */
+const char *const *client_enabled_features(struct client *client);
+
+/* Send client processing to imap-idle process. If successful, returns TRUE
+   and destroys the client. If hibernation failed, the exact reason is
+   returned (mainly for unit tests). */
+bool imap_client_hibernate(struct client **client, const char **reason_r);
+
+struct imap_search_update *
+client_search_update_lookup(struct client *client, const char *tag,
+			    unsigned int *idx_r);
+void client_search_updates_free(struct client *client);
+
+struct client_command_context *client_command_alloc(struct client *client);
+void client_command_init_finished(struct client_command_context *cmd);
+void client_command_cancel(struct client_command_context **cmd);
+void client_command_free(struct client_command_context **cmd);
+
+bool client_handle_unfinished_cmd(struct client_command_context *cmd);
+/* Handle any pending command input. This must be run at the end of all
+   I/O callbacks after they've (potentially) finished some commands. */
+void client_continue_pending_input(struct client *client);
+void client_add_missing_io(struct client *client);
+const char *client_stats(struct client *client);
+
+void client_input(struct client *client);
+bool client_handle_input(struct client *client);
+int client_output(struct client *client);
+
+void clients_init(void);
+void clients_destroy_all(void);
+
+#endif
diff --git a/src/imap/imap-commands-util.c b/src/imap/imap-commands-util.c
new file mode 100644
index 0000000..2d454a7
--- /dev/null
+++ b/src/imap/imap-commands-util.c
@@ -0,0 +1,402 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "array.h"
+#include "buffer.h"
+#include "str.h"
+#include "str-sanitize.h"
+#include "imap-resp-code.h"
+#include "imap-parser.h"
+#include "imap-sync.h"
+#include "imap-utf7.h"
+#include "imap-util.h"
+#include "mail-storage.h"
+#include "mail-namespace.h"
+#include "imap-commands-util.h"
+
+struct mail_namespace *
+client_find_namespace_full(struct client *client,
+			   const char **mailbox, const char **client_error_r)
+{
+	struct mail_namespace *namespaces = client->user->namespaces;
+	struct mail_namespace *ns;
+	string_t *utf8_name;
+
+	utf8_name = t_str_new(64);
+	if (imap_utf7_to_utf8(*mailbox, utf8_name) < 0) {
+		*client_error_r = "NO Mailbox name is not valid mUTF-7";
+		return NULL;
+	}
+
+	ns = mail_namespace_find(namespaces, str_c(utf8_name));
+	if ((ns->flags & NAMESPACE_FLAG_AUTOCREATED) != 0 &&
+	    ns->prefix_len == 0) {
+		/* this matched only the autocreated prefix="" namespace.
+		   give a nice human-readable error message */
+		*client_error_r = t_strdup_printf(
+			"NO Client tried to access nonexistent namespace. "
+			"(Mailbox name should probably be prefixed with: %s)",
+			mail_namespace_find_inbox(namespaces)->prefix);
+		return NULL;
+	}
+
+	if ((client->set->parsed_workarounds &
+	     		WORKAROUND_TB_EXTRA_MAILBOX_SEP) != 0 &&
+	    str_len(utf8_name) > 0 &&
+	    str_c(utf8_name)[str_len(utf8_name)-1] == mail_namespace_get_sep(ns)) {
+		/* drop the extra trailing hierarchy separator */
+		str_truncate(utf8_name, str_len(utf8_name)-1);
+	}
+
+	*mailbox = str_c(utf8_name);
+	return ns;
+}
+
+struct mail_namespace *
+client_find_namespace(struct client_command_context *cmd, const char **mailbox)
+{
+	struct mail_namespace *ns;
+	const char *client_error;
+
+	ns = client_find_namespace_full(cmd->client, mailbox, &client_error);
+	if (ns == NULL)
+		client_send_tagline(cmd, client_error);
+	return ns;
+}
+
+bool client_verify_open_mailbox(struct client_command_context *cmd)
+{
+	if (cmd->client->mailbox != NULL) {
+		event_add_str(cmd->global_event, "mailbox",
+			      mailbox_get_vname(cmd->client->mailbox));
+		return TRUE;
+	} else {
+		client_send_tagline(cmd, "BAD No mailbox selected.");
+		return FALSE;
+	}
+}
+
+void imap_client_close_mailbox(struct client *client)
+{
+	struct mailbox *box;
+
+	i_assert(client->mailbox != NULL);
+
+	if (array_is_created(&client->fetch_failed_uids))
+		array_clear(&client->fetch_failed_uids);
+	client_search_updates_free(client);
+	array_free(&client->search_saved_uidset);
+
+	box = client->mailbox;
+	client->mailbox = NULL;
+
+	mailbox_free(&box);
+	client_update_mailbox_flags(client, NULL);
+}
+
+int client_open_save_dest_box(struct client_command_context *cmd,
+			      const char *name, struct mailbox **destbox_r)
+{
+	struct mail_namespace *ns;
+	struct mailbox *box;
+	const char *error_string;
+	enum mail_error error;
+
+	ns = client_find_namespace(cmd, &name);
+	if (ns == NULL)
+		return -1;
+
+	if (cmd->client->mailbox != NULL &&
+	    mailbox_equals(cmd->client->mailbox, ns, name)) {
+		*destbox_r = cmd->client->mailbox;
+		return 0;
+	}
+	box = mailbox_alloc(ns->list, name, MAILBOX_FLAG_SAVEONLY);
+	if (mailbox_open(box) < 0) {
+		error_string = mailbox_get_last_error(box, &error);
+		if (error == MAIL_ERROR_NOTFOUND) {
+			client_send_tagline(cmd,  t_strdup_printf(
+				"NO [TRYCREATE] %s", error_string));
+		} else {
+			client_send_box_error(cmd, box);
+		}
+		mailbox_free(&box);
+		return -1;
+	}
+	if (mailbox_enable(box, client_enabled_mailbox_features(cmd->client)) < 0) {
+		client_send_box_error(cmd, box);
+		mailbox_free(&box);
+		return -1;
+	}
+	*destbox_r = box;
+	return 0;
+}
+
+const char *imap_client_command_get_reason(struct client_command_context *cmd)
+{
+	return cmd->args[0] == '\0' ? cmd->name :
+		t_strdup_printf("%s %s", cmd->name, cmd->human_args);
+}
+
+const char *
+imap_get_error_string(struct client_command_context *cmd,
+		      const char *error_string, enum mail_error error)
+{
+	const char *resp_code = NULL;
+
+	switch (error) {
+	case MAIL_ERROR_NONE:
+		break;
+	case MAIL_ERROR_TEMP:
+	case MAIL_ERROR_LOOKUP_ABORTED: /* BUG: shouldn't be visible here */
+		resp_code = IMAP_RESP_CODE_SERVERBUG;
+		break;
+	case MAIL_ERROR_UNAVAILABLE:
+		resp_code = IMAP_RESP_CODE_UNAVAILABLE;
+		break;
+	case MAIL_ERROR_NOTPOSSIBLE:
+	case MAIL_ERROR_PARAMS:
+		resp_code = IMAP_RESP_CODE_CANNOT;
+		break;
+	case MAIL_ERROR_PERM:
+		resp_code = IMAP_RESP_CODE_NOPERM;
+		break;
+	case MAIL_ERROR_NOQUOTA:
+		resp_code = IMAP_RESP_CODE_OVERQUOTA;
+		break;
+	case MAIL_ERROR_NOTFOUND:
+		if ((cmd->cmd_flags & COMMAND_FLAG_USE_NONEXISTENT) != 0)
+			resp_code = IMAP_RESP_CODE_NONEXISTENT;
+		break;
+	case MAIL_ERROR_EXISTS:
+		resp_code = IMAP_RESP_CODE_ALREADYEXISTS;
+		break;
+	case MAIL_ERROR_EXPUNGED:
+		resp_code = IMAP_RESP_CODE_EXPUNGEISSUED;
+		break;
+	case MAIL_ERROR_INUSE:
+		resp_code = IMAP_RESP_CODE_INUSE;
+		break;
+	case MAIL_ERROR_CONVERSION:
+	case MAIL_ERROR_INVALIDDATA:
+		break;
+	case MAIL_ERROR_LIMIT:
+		resp_code = IMAP_RESP_CODE_LIMIT;
+		break;
+	}
+	if (resp_code == NULL || *error_string == '[')
+		return t_strconcat("NO ", error_string, NULL);
+	else
+		return t_strdup_printf("NO [%s] %s", resp_code, error_string);
+}
+
+void client_send_error(struct client_command_context *cmd,
+		       const char *error_string, enum mail_error error)
+{
+	client_send_tagline(cmd, imap_get_error_string(cmd, error_string,
+						       error));
+	client_disconnect_if_inconsistent(cmd->client);
+}
+
+void client_send_list_error(struct client_command_context *cmd,
+			    struct mailbox_list *list)
+{
+	const char *error_string;
+	enum mail_error error;
+
+	error_string = mailbox_list_get_last_error(list, &error);
+	client_send_tagline(cmd, imap_get_error_string(cmd, error_string,
+						       error));
+}
+
+void client_disconnect_if_inconsistent(struct client *client)
+{
+	if (client->mailbox != NULL &&
+	    mailbox_is_inconsistent(client->mailbox)) {
+		/* we can't do forced CLOSE, so have to disconnect */
+		client_disconnect_with_error(client,
+			"IMAP session state is inconsistent, please relogin.");
+	}
+}
+
+void client_send_box_error(struct client_command_context *cmd,
+			   struct mailbox *box)
+{
+	client_send_storage_error(cmd, mailbox_get_storage(box));
+}
+
+void client_send_storage_error(struct client_command_context *cmd,
+			       struct mail_storage *storage)
+{
+	const char *error_string;
+	enum mail_error error;
+
+	error_string = mail_storage_get_last_error(storage, &error);
+	client_send_error(cmd, error_string, error);
+}
+
+void client_send_untagged_storage_error(struct client *client,
+					struct mail_storage *storage)
+{
+	const char *error_string;
+	enum mail_error error;
+
+	error_string = mail_storage_get_last_error(storage, &error);
+	client_send_line(client, t_strconcat("* NO ", error_string, NULL));
+
+	client_disconnect_if_inconsistent(client);
+}
+
+bool client_parse_mail_flags(struct client_command_context *cmd,
+			     const struct imap_arg *args,
+			     enum mail_flags *flags_r,
+			     const char *const **keywords_r)
+{
+	const char *atom;
+	enum mail_flags flag;
+	ARRAY(const char *) keywords;
+
+	*flags_r = 0;
+	*keywords_r = NULL;
+	p_array_init(&keywords, cmd->pool, 16);
+
+	while (!IMAP_ARG_IS_EOL(args)) {
+		if (!imap_arg_get_atom(args, &atom)) {
+			client_send_command_error(cmd,
+				"Flags list contains non-atoms.");
+			return FALSE;
+		}
+
+		if (*atom == '\\') {
+			/* system flag */
+			atom = t_str_ucase(atom);
+			flag = imap_parse_system_flag(atom);
+			if (flag != 0 && flag != MAIL_RECENT)
+				*flags_r |= flag;
+			else {
+				client_send_command_error(cmd, t_strconcat(
+					"Invalid system flag ", atom, NULL));
+				return FALSE;
+			}
+		} else {
+			/* keyword validity checks are done by lib-storage */
+			array_push_back(&keywords, &atom);
+		}
+
+		args++;
+	}
+
+	if (array_count(&keywords) == 0)
+		*keywords_r = NULL;
+	else {
+		array_append_zero(&keywords); /* NULL-terminate */
+		*keywords_r = array_front(&keywords);
+	}
+	return TRUE;
+}
+
+void client_send_mailbox_flags(struct client *client, bool selecting)
+{
+	struct mailbox_status status;
+	unsigned int count = array_count(client->keywords.names);
+	const char *const *keywords;
+	string_t *str;
+
+	if (!selecting && count == client->keywords.announce_count) {
+		/* no changes to keywords and we're not selecting a mailbox */
+		return;
+	}
+
+	client->keywords.announce_count = count;
+	mailbox_get_open_status(client->mailbox, STATUS_PERMANENT_FLAGS,
+				&status);
+
+	keywords = count == 0 ? NULL :
+		array_front(client->keywords.names);
+	str = t_str_new(128);
+	str_append(str, "* FLAGS (");
+	imap_write_flags(str, status.flags, keywords);
+	str_append_c(str, ')');
+	client_send_line(client, str_c(str));
+
+	if (!status.permanent_keywords)
+		keywords = NULL;
+
+	str_truncate(str, 0);
+	str_append(str, "* OK [PERMANENTFLAGS (");
+	imap_write_flags(str, status.permanent_flags, keywords);
+	if (status.allow_new_keywords) {
+		if (status.permanent_flags != 0 || keywords != NULL)
+			str_append_c(str, ' ');
+		str_append(str, "\\*");
+	}
+	str_append(str, ")] ");
+
+	if (mailbox_is_readonly(client->mailbox))
+		str_append(str, "Read-only mailbox.");
+	else
+		str_append(str, "Flags permitted.");
+	client_send_line(client, str_c(str));
+}
+
+void client_update_mailbox_flags(struct client *client,
+				 const ARRAY_TYPE(keywords) *keywords)
+{
+	client->keywords.names = keywords;
+	client->keywords.announce_count = 0;
+}
+
+const char *const *
+client_get_keyword_names(struct client *client, ARRAY_TYPE(keywords) *dest,
+			 const ARRAY_TYPE(keyword_indexes) *src)
+{
+	unsigned int kw_index;
+	const char *const *all_names;
+	unsigned int all_count;
+
+	client_send_mailbox_flags(client, FALSE);
+
+	/* convert indexes to names */
+	all_names = array_get(client->keywords.names, &all_count);
+	array_clear(dest);
+	array_foreach_elem(src, kw_index) {
+		i_assert(kw_index < all_count);
+		array_push_back(dest, &all_names[kw_index]);
+	}
+
+	array_append_zero(dest);
+	return array_front(dest);
+}
+
+void msgset_generator_init(struct msgset_generator_context *ctx, string_t *str)
+{
+	i_zero(ctx);
+	ctx->str = str;
+	ctx->last_uid = (uint32_t)-1;
+}
+
+void msgset_generator_next(struct msgset_generator_context *ctx, uint32_t uid)
+{
+	i_assert(uid > 0);
+
+	if (uid-1 != ctx->last_uid) {
+		if (ctx->first_uid == 0)
+			;
+		else if (ctx->first_uid == ctx->last_uid)
+			str_printfa(ctx->str, "%u,", ctx->first_uid);
+		else {
+			str_printfa(ctx->str, "%u:%u,",
+				    ctx->first_uid, ctx->last_uid);
+		}
+		ctx->first_uid = uid;
+	}
+	ctx->last_uid = uid;
+}
+
+void msgset_generator_finish(struct msgset_generator_context *ctx)
+{
+	if (ctx->first_uid == ctx->last_uid)
+		str_printfa(ctx->str, "%u", ctx->first_uid);
+	else
+		str_printfa(ctx->str, "%u:%u", ctx->first_uid, ctx->last_uid);
+}
diff --git a/src/imap/imap-commands-util.h b/src/imap/imap-commands-util.h
new file mode 100644
index 0000000..997ed02
--- /dev/null
+++ b/src/imap/imap-commands-util.h
@@ -0,0 +1,81 @@
+#ifndef IMAP_COMMANDS_UTIL_H
+#define IMAP_COMMANDS_UTIL_H
+
+struct msgset_generator_context {
+	string_t *str;
+	uint32_t first_uid, last_uid;
+};
+
+struct mail_full_flags;
+struct mailbox_keywords;
+
+/* Finds namespace for given mailbox from namespaces. If namespace isn't found
+   or mailbox name is invalid, sends a tagged NO reply to client. */
+struct mail_namespace *
+client_find_namespace(struct client_command_context *cmd, const char **mailbox);
+struct mail_namespace *
+client_find_namespace_full(struct client *client,
+			   const char **mailbox, const char **client_error_r);
+
+/* Returns TRUE if mailbox is selected. If not, sends "No mailbox selected"
+   error message to client. */
+bool client_verify_open_mailbox(struct client_command_context *cmd);
+/* Close the selected mailbox. */
+void imap_client_close_mailbox(struct client *client);
+
+/* Open APPEND/COPY destination mailbox. */
+int client_open_save_dest_box(struct client_command_context *cmd,
+			      const char *name, struct mailbox **destbox_r);
+
+/* Returns string based in IMAP command name and parameters. */
+const char *imap_client_command_get_reason(struct client_command_context *cmd);
+/* Set transaction's reason to the IMAP command name and parameters. */
+void imap_transaction_set_cmd_reason(struct mailbox_transaction_context *trans,
+				     struct client_command_context *cmd);
+const char *
+imap_get_error_string(struct client_command_context *cmd,
+		      const char *error_string, enum mail_error error);
+
+void client_disconnect_if_inconsistent(struct client *client);
+
+/* Send an explicit error message to client. */
+void client_send_error(struct client_command_context *cmd,
+		       const char *error_string, enum mail_error error);
+/* Send last mailbox list error message to client. */
+void client_send_list_error(struct client_command_context *cmd,
+			    struct mailbox_list *list);
+/* Send last mail storage error message to client. */
+void client_send_storage_error(struct client_command_context *cmd,
+			       struct mail_storage *storage);
+/* Send last mailbox's storage error message to client. */
+void client_send_box_error(struct client_command_context *cmd,
+			   struct mailbox *box);
+
+/* Send untagged error message to client. */
+void client_send_untagged_storage_error(struct client *client,
+					struct mail_storage *storage);
+
+/* Parse flags. Returns TRUE if successful, if not sends an error message to
+   client. */
+bool client_parse_mail_flags(struct client_command_context *cmd,
+			     const struct imap_arg *args,
+			     enum mail_flags *flags_r,
+			     const char *const **keywords_r);
+
+/* Send FLAGS + PERMANENTFLAGS to client if they have changed,
+   or if selecting=TRUE. */
+void client_send_mailbox_flags(struct client *client, bool selecting);
+/* Update client->keywords array. Use keywords=NULL when unselecting. */
+void client_update_mailbox_flags(struct client *client,
+				 const ARRAY_TYPE(keywords) *keywords)
+	ATTR_NULL(2);
+/* Convert keyword indexes to keyword names in selected mailbox. */
+const char *const *
+client_get_keyword_names(struct client *client, ARRAY_TYPE(keywords) *dest,
+			 const ARRAY_TYPE(keyword_indexes) *src);
+
+void msgset_generator_init(struct msgset_generator_context *ctx, string_t *str);
+void msgset_generator_next(struct msgset_generator_context *ctx, uint32_t uid);
+void msgset_generator_finish(struct msgset_generator_context *ctx);
+
+#endif
diff --git a/src/imap/imap-commands.c b/src/imap/imap-commands.c
new file mode 100644
index 0000000..b78d0a1
--- /dev/null
+++ b/src/imap/imap-commands.c
@@ -0,0 +1,247 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "array.h"
+#include "buffer.h"
+#include "ioloop.h"
+#include "istream.h"
+#include "ostream.h"
+#include "time-util.h"
+#include "imap-commands.h"
+
+
+struct command_hook {
+	command_hook_callback_t *pre;
+	command_hook_callback_t *post;
+};
+
+static const struct command imap4rev1_commands[] = {
+	{ "CAPABILITY",		cmd_capability,  0 },
+	{ "LOGOUT",		cmd_logout,      COMMAND_FLAG_BREAKS_MAILBOX },
+	{ "NOOP",		cmd_noop,        COMMAND_FLAG_BREAKS_SEQS },
+
+	{ "APPEND",		cmd_append,      COMMAND_FLAG_BREAKS_SEQS |
+						 /* finish syncing and sending
+						    all tagged commands before
+						    we wait for APPEND input */
+						 COMMAND_FLAG_BREAKS_MAILBOX },
+	{ "EXAMINE",		cmd_examine,     COMMAND_FLAG_BREAKS_MAILBOX },
+	{ "CREATE",		cmd_create,      0 },
+	{ "DELETE",		cmd_delete,      COMMAND_FLAG_BREAKS_MAILBOX |
+						 COMMAND_FLAG_USE_NONEXISTENT },
+	{ "RENAME",		cmd_rename,      COMMAND_FLAG_USE_NONEXISTENT },
+	{ "LIST",		cmd_list,        0 },
+	{ "LSUB",		cmd_lsub,        0 },
+	{ "SELECT",		cmd_select,      COMMAND_FLAG_BREAKS_MAILBOX },
+	{ "STATUS",		cmd_status,      0 },
+	{ "SUBSCRIBE",		cmd_subscribe,   0 },
+	{ "UNSUBSCRIBE",	cmd_unsubscribe, COMMAND_FLAG_USE_NONEXISTENT },
+
+	{ "CHECK",		cmd_check,       COMMAND_FLAG_BREAKS_SEQS },
+	{ "CLOSE",		cmd_close,       COMMAND_FLAG_BREAKS_MAILBOX },
+	{ "COPY",		cmd_copy,        COMMAND_FLAG_USES_SEQS |
+						 COMMAND_FLAG_BREAKS_SEQS },
+	{ "EXPUNGE",		cmd_expunge,     COMMAND_FLAG_BREAKS_SEQS },
+	{ "FETCH",		cmd_fetch,       COMMAND_FLAG_USES_SEQS },
+	{ "SEARCH",		cmd_search,      COMMAND_FLAG_USES_SEQS },
+	{ "STORE",		cmd_store,       COMMAND_FLAG_USES_SEQS },
+	{ "UID COPY",		cmd_copy,        COMMAND_FLAG_BREAKS_SEQS },
+	{ "UID FETCH",		cmd_fetch,       COMMAND_FLAG_BREAKS_SEQS },
+	{ "UID SEARCH",		cmd_search,      COMMAND_FLAG_BREAKS_SEQS },
+	{ "UID STORE",		cmd_store,       COMMAND_FLAG_BREAKS_SEQS }
+};
+#define IMAP4REV1_COMMANDS_COUNT N_ELEMENTS(imap4rev1_commands)
+
+static const struct command imap_ext_commands[] = {
+	/* IMAP extensions: */
+	{ "CANCELUPDATE",	cmd_cancelupdate,0 },
+	{ "ENABLE",		cmd_enable,      0 },
+	{ "ID",			cmd_id,          0 },
+	{ "IDLE",		cmd_idle,        COMMAND_FLAG_BREAKS_SEQS |
+						 COMMAND_FLAG_REQUIRES_SYNC |
+						 /* finish syncing and sending
+						    all tagged commands before
+						    IDLE is started */
+						 COMMAND_FLAG_BREAKS_MAILBOX },
+	{ "GETMETADATA",	cmd_getmetadata, 0 },
+	{ "SETMETADATA",	cmd_setmetadata, 0 },
+	{ "NAMESPACE",		cmd_namespace,   0 },
+	{ "NOTIFY",		cmd_notify,      COMMAND_FLAG_BREAKS_SEQS },
+	{ "SORT",		cmd_sort,        COMMAND_FLAG_USES_SEQS },
+	{ "THREAD",		cmd_thread,      COMMAND_FLAG_USES_SEQS },
+	{ "UID EXPUNGE",	cmd_uid_expunge, COMMAND_FLAG_BREAKS_SEQS },
+	{ "MOVE",		cmd_move,        COMMAND_FLAG_USES_SEQS |
+						 COMMAND_FLAG_BREAKS_SEQS },
+	{ "UID MOVE",		cmd_move,        COMMAND_FLAG_BREAKS_SEQS },
+	{ "UID SORT",		cmd_sort,        COMMAND_FLAG_BREAKS_SEQS },
+	{ "UID THREAD",		cmd_thread,      COMMAND_FLAG_BREAKS_SEQS },
+	{ "UNSELECT",		cmd_unselect,    COMMAND_FLAG_BREAKS_MAILBOX },
+	{ "X-CANCEL",		cmd_x_cancel,    0 },
+	{ "X-STATE",		cmd_x_state,     COMMAND_FLAG_REQUIRES_SYNC },
+	{ "XLIST",		cmd_list,        0 },
+	/* IMAP URLAUTH (RFC4467): */
+	{ "GENURLAUTH",		cmd_genurlauth,  0 },
+	{ "RESETKEY",		cmd_resetkey,    0 },
+	{ "URLFETCH",		cmd_urlfetch,    0 }
+};
+#define IMAP_EXT_COMMANDS_COUNT N_ELEMENTS(imap_ext_commands)
+
+ARRAY_TYPE(command) imap_commands;
+static bool commands_unsorted;
+static ARRAY(struct command_hook) command_hooks;
+
+void command_register(const char *name, command_func_t *func,
+		      enum command_flags flags)
+{
+	struct command cmd;
+
+	i_zero(&cmd);
+	cmd.name = name;
+	cmd.func = func;
+	cmd.flags = flags;
+	array_push_back(&imap_commands, &cmd);
+
+	commands_unsorted = TRUE;
+}
+
+void command_unregister(const char *name)
+{
+	const struct command *cmd;
+	unsigned int i, count;
+
+	cmd = array_get(&imap_commands, &count);
+	for (i = 0; i < count; i++) {
+		if (strcasecmp(cmd[i].name, name) == 0) {
+			array_delete(&imap_commands, i, 1);
+			return;
+		}
+	}
+
+	i_error("Trying to unregister unknown command '%s'", name);
+}
+
+void command_register_array(const struct command *cmdarr, unsigned int count)
+{
+	commands_unsorted = TRUE;
+	array_append(&imap_commands, cmdarr, count);
+}
+
+void command_unregister_array(const struct command *cmdarr, unsigned int count)
+{
+	while (count > 0) {
+		command_unregister(cmdarr->name);
+		count--; cmdarr++;
+	}
+}
+
+void command_hook_register(command_hook_callback_t *pre,
+			   command_hook_callback_t *post)
+{
+	struct command_hook hook;
+
+	hook.pre = pre;
+	hook.post = post;
+	array_push_back(&command_hooks, &hook);
+}
+
+void command_hook_unregister(command_hook_callback_t *pre,
+			     command_hook_callback_t *post)
+{
+	const struct command_hook *hooks;
+	unsigned int i, count;
+
+	hooks = array_get(&command_hooks, &count);
+	for (i = 0; i < count; i++) {
+		if (hooks[i].pre == pre && hooks[i].post == post) {
+			array_delete(&command_hooks, i, 1);
+			return;
+		}
+	}
+	i_panic("command_hook_unregister(): hook not registered");
+}
+
+void command_stats_start(struct client_command_context *cmd)
+{
+	cmd->stats_start.timeval = ioloop_timeval;
+	cmd->stats_start.lock_wait_usecs = file_lock_wait_get_total_usecs();
+	cmd->stats_start.bytes_in = i_stream_get_absolute_offset(cmd->client->input);
+	cmd->stats_start.bytes_out = cmd->client->output->offset;
+}
+
+void command_stats_flush(struct client_command_context *cmd)
+{
+	io_loop_time_refresh();
+	cmd->stats.running_usecs +=
+		timeval_diff_usecs(&ioloop_timeval, &cmd->stats_start.timeval);
+	cmd->stats.lock_wait_usecs +=
+		file_lock_wait_get_total_usecs() -
+		cmd->stats_start.lock_wait_usecs;
+	cmd->stats.bytes_in += i_stream_get_absolute_offset(cmd->client->input) -
+		cmd->stats_start.bytes_in;
+	cmd->stats.bytes_out += cmd->client->output->offset -
+		cmd->stats_start.bytes_out;
+	/* allow flushing multiple times */
+	command_stats_start(cmd);
+}
+
+bool command_exec(struct client_command_context *cmd)
+{
+	const struct command_hook *hook;
+	bool finished;
+
+	i_assert(!cmd->executing);
+
+	io_loop_time_refresh();
+	command_stats_start(cmd);
+
+	event_push_global(cmd->global_event);
+	cmd->executing = TRUE;
+	array_foreach(&command_hooks, hook)
+		hook->pre(cmd);
+	finished = cmd->func(cmd);
+	array_foreach(&command_hooks, hook)
+		hook->post(cmd);
+	cmd->executing = FALSE;
+	event_pop_global(cmd->global_event);
+	if (cmd->state == CLIENT_COMMAND_STATE_DONE)
+		finished = TRUE;
+
+	command_stats_flush(cmd);
+	return finished;
+}
+
+static int command_cmp(const struct command *c1, const struct command *c2)
+{
+	return strcasecmp(c1->name, c2->name);
+}
+
+static int command_bsearch(const char *name, const struct command *cmd)
+{
+	return strcasecmp(name, cmd->name);
+}
+
+struct command *command_find(const char *name)
+{
+	if (commands_unsorted) {
+		array_sort(&imap_commands, command_cmp);
+                commands_unsorted = FALSE;
+	}
+
+	return array_bsearch(&imap_commands, name, command_bsearch);
+}
+
+void commands_init(void)
+{
+	i_array_init(&imap_commands, 64);
+	i_array_init(&command_hooks, 4);
+	commands_unsorted = FALSE;
+
+        command_register_array(imap4rev1_commands, IMAP4REV1_COMMANDS_COUNT);
+        command_register_array(imap_ext_commands, IMAP_EXT_COMMANDS_COUNT);
+}
+
+void commands_deinit(void)
+{
+	array_free(&imap_commands);
+	array_free(&command_hooks);
+}
diff --git a/src/imap/imap-commands.h b/src/imap/imap-commands.h
new file mode 100644
index 0000000..651a6df
--- /dev/null
+++ b/src/imap/imap-commands.h
@@ -0,0 +1,137 @@
+#ifndef IMAP_COMMANDS_H
+#define IMAP_COMMANDS_H
+
+struct client_command_context;
+
+#include "mail-storage.h"
+#include "mail-namespace.h"
+#include "imap-parser.h"
+#include "imap-sync.h"
+#include "imap-commands-util.h"
+
+typedef bool command_func_t(struct client_command_context *cmd);
+typedef void command_hook_callback_t(struct client_command_context *ctx);
+
+enum command_flags {
+	/* Command uses sequences as its input parameters */
+	COMMAND_FLAG_USES_SEQS		= 0x01,
+	/* Command may reply with EXPUNGE, causing sequences to break */
+	COMMAND_FLAG_BREAKS_SEQS	= 0x02,
+	/* Command changes the mailbox */
+	COMMAND_FLAG_BREAKS_MAILBOX	= 0x04 | COMMAND_FLAG_BREAKS_SEQS,
+
+	/* Command uses selected mailbox */
+	COMMAND_FLAG_USES_MAILBOX	= COMMAND_FLAG_BREAKS_MAILBOX |
+					  COMMAND_FLAG_USES_SEQS,
+
+	/* Command requires mailbox syncing before it can do its job. */
+	COMMAND_FLAG_REQUIRES_SYNC	= 0x08,
+	/* Command allows replying with [NONEXISTENT] imap resp code.
+	   Dovecot internally returns it for all kinds of commands,
+	   but unfortunately RFC 5530 specifies it only for "delete something"
+	   operations. */
+	COMMAND_FLAG_USE_NONEXISTENT	= 0x10
+};
+
+struct command {
+	const char *name;
+	command_func_t *func;
+
+	enum command_flags flags;
+};
+ARRAY_DEFINE_TYPE(command, struct command);
+
+extern ARRAY_TYPE(command) imap_commands;
+
+/* Register command. Given name parameter must be permanently stored until
+   command is unregistered. */
+void command_register(const char *name, command_func_t *func,
+		      enum command_flags flags);
+void command_unregister(const char *name);
+
+/* Register array of commands. */
+void command_register_array(const struct command *cmdarr, unsigned int count);
+void command_unregister_array(const struct command *cmdarr, unsigned int count);
+
+/* Register hook callbacks that are called before and after all commands */
+void command_hook_register(command_hook_callback_t *pre,
+			   command_hook_callback_t *post);
+void command_hook_unregister(command_hook_callback_t *pre,
+			     command_hook_callback_t *post);
+/* Execute command and hooks */
+bool command_exec(struct client_command_context *cmd);
+/* Starts counting command statistics. */
+void command_stats_start(struct client_command_context *cmd);
+/* Finish counting command statistics. This is called automatically when
+   command_exec() returns, but it should be called explicitly if the stats are
+   needed during command_exec(). */
+void command_stats_flush(struct client_command_context *cmd);
+
+struct command *command_find(const char *name);
+
+void commands_init(void);
+void commands_deinit(void);
+
+/* IMAP4rev1 commands: */
+
+/* Non-Authenticated State */
+bool cmd_logout(struct client_command_context *cmd);
+
+bool cmd_capability(struct client_command_context *cmd);
+bool cmd_noop(struct client_command_context *cmd);
+
+/* Authenticated State */
+bool cmd_select(struct client_command_context *cmd);
+bool cmd_examine(struct client_command_context *cmd);
+
+bool cmd_create(struct client_command_context *cmd);
+bool cmd_delete(struct client_command_context *cmd);
+bool cmd_rename(struct client_command_context *cmd);
+
+bool cmd_subscribe(struct client_command_context *cmd);
+bool cmd_unsubscribe(struct client_command_context *cmd);
+
+bool cmd_list(struct client_command_context *cmd);
+bool cmd_lsub(struct client_command_context *cmd);
+
+bool cmd_status(struct client_command_context *cmd);
+bool cmd_append(struct client_command_context *cmd);
+
+/* Selected state */
+bool cmd_check(struct client_command_context *cmd);
+bool cmd_close(struct client_command_context *cmd);
+bool cmd_expunge(struct client_command_context *cmd);
+bool cmd_search(struct client_command_context *cmd);
+bool cmd_fetch(struct client_command_context *cmd);
+bool cmd_store(struct client_command_context *cmd);
+bool cmd_copy(struct client_command_context *cmd);
+bool cmd_uid(struct client_command_context *cmd);
+
+/* IMAP extensions: */
+bool cmd_cancelupdate(struct client_command_context *cmd);
+bool cmd_enable(struct client_command_context *cmd);
+bool cmd_id(struct client_command_context *cmd);
+bool cmd_idle(struct client_command_context *cmd);
+bool cmd_namespace(struct client_command_context *cmd);
+bool cmd_getmetadata(struct client_command_context *cmd);
+bool cmd_setmetadata(struct client_command_context *cmd);
+bool cmd_notify(struct client_command_context *cmd);
+bool cmd_sort(struct client_command_context *cmd);
+bool cmd_thread(struct client_command_context *cmd);
+bool cmd_uid_expunge(struct client_command_context *cmd);
+bool cmd_move(struct client_command_context *cmd);
+bool cmd_unselect(struct client_command_context *cmd);
+bool cmd_x_cancel(struct client_command_context *cmd);
+bool cmd_x_state(struct client_command_context *cmd);
+
+/* IMAP URLAUTH (RFC4467): */
+bool cmd_genurlauth(struct client_command_context *cmd);
+bool cmd_resetkey(struct client_command_context *cmd);
+bool cmd_urlfetch(struct client_command_context *cmd);
+
+/* private: */
+bool cmd_list_full(struct client_command_context *cmd, bool lsub);
+bool cmd_select_full(struct client_command_context *cmd, bool readonly);
+bool cmd_subscribe_full(struct client_command_context *cmd, bool subscribe);
+
+#endif
diff --git a/src/imap/imap-common.h b/src/imap/imap-common.h
new file mode 100644
index 0000000..1609a8b
--- /dev/null
+++ b/src/imap/imap-common.h
@@ -0,0 +1,40 @@
+#ifndef IMAP_COMMON_H
+#define IMAP_COMMON_H
+
+/* Disconnect client after idling this many milliseconds */
+#define CLIENT_IDLE_TIMEOUT_MSECS (60*30*1000)
+
+/* If we can't send anything to client for this long, disconnect the client */
+#define CLIENT_OUTPUT_TIMEOUT_MSECS (5*60*1000)
+
+/* Stop buffering more data into output stream after this many bytes */
+#define CLIENT_OUTPUT_OPTIMAL_SIZE 2048
+
+/* Disconnect client when it sends too many bad commands in a row */
+#define CLIENT_MAX_BAD_COMMANDS 20
+
+#include "lib.h"
+#include "imap-client.h"
+#include "imap-settings.h"
+
+struct mail_storage_service_input;
+
+typedef void imap_client_created_func_t(struct client **client);
+
+extern imap_client_created_func_t *hook_client_created;
+extern bool imap_debug;
+extern struct event_category event_category_imap;
+
+/* Sets the hook_client_created and returns the previous hook,
+   which the new_hook should call if it's non-NULL. */
+imap_client_created_func_t * ATTR_NOWARN_UNUSED_RESULT
+imap_client_created_hook_set(imap_client_created_func_t *new_hook);
+
+void imap_refresh_proctitle(void);
+void imap_refresh_proctitle_delayed(void);
+
+int client_create_from_input(const struct mail_storage_service_input *input,
+			     int fd_in, int fd_out, struct client **client_r,
+			     const char **error_r);
+
+#endif
diff --git a/src/imap/imap-expunge.c b/src/imap/imap-expunge.c
new file mode 100644
index 0000000..ff1a213
--- /dev/null
+++ b/src/imap/imap-expunge.c
@@ -0,0 +1,111 @@
+/* Copyright (c) 2003-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "mail-storage.h"
+#include "mail-search-build.h"
+#include "imap-search-args.h"
+#include "imap-expunge.h"
+
+#define IMAP_EXPUNGE_BATCH_SIZE 1000
+
+/* get a seqset of all the mails with \Deleted */
+static int imap_expunge_get_seqset(struct mailbox *box,
+				   struct mail_search_arg *next_search_arg,
+				   ARRAY_TYPE(seq_range) *seqset)
+{
+	struct mailbox_transaction_context *t;
+	struct mail_search_args *search_args;
+	struct mail_search_context *ctx;
+	struct mail *mail;
+	int ret;
+
+	search_args = mail_search_build_init();
+	search_args->args = p_new(search_args->pool, struct mail_search_arg, 1);
+	search_args->args->type = SEARCH_FLAGS;
+	search_args->args->value.flags = MAIL_DELETED;
+	search_args->args->next = next_search_arg;
+
+	/* Refresh the flags so we'll expunge all messages marked as \Deleted
+	   by any session. */
+	t = mailbox_transaction_begin(box, MAILBOX_TRANSACTION_FLAG_REFRESH,
+				      "EXPUNGE");
+	ctx = mailbox_search_init(t, search_args, NULL, 0, NULL);
+
+	/* collect the seqs into a seqset */
+	while (mailbox_search_next(ctx, &mail))
+		seq_range_array_add(seqset, mail->seq);
+
+	ret = mailbox_search_deinit(&ctx);
+	/* commit in case a plugin made changes - failures should not abort the expunge */
+	(void) mailbox_transaction_commit(&t);
+	mail_search_args_unref(&search_args);
+
+	if (ret < 0)
+		array_free(seqset);
+
+	return ret;
+}
+
+int imap_expunge(struct mailbox *box, struct mail_search_arg *next_search_arg,
+		 unsigned int *expunged_count)
+{
+	struct imap_search_seqset_iter *seqset_iter;
+	struct mail_search_args *search_args;
+	struct mailbox_status status;
+	bool expunges = FALSE;
+	int ret;
+
+	if (mailbox_is_readonly(box)) {
+		/* silently ignore */
+		return 0;
+	}
+
+	mailbox_get_open_status(box, STATUS_MESSAGES, &status);
+
+	search_args = mail_search_build_init();
+	search_args->args = p_new(search_args->pool, struct mail_search_arg, 1);
+	search_args->args->type = SEARCH_SEQSET;
+	p_array_init(&search_args->args->value.seqset, search_args->pool, 16);
+
+	if (imap_expunge_get_seqset(box, next_search_arg,
+				    &search_args->args->value.seqset) < 0) {
+		mail_search_args_unref(&search_args);
+		return -1;
+	}
+
+	seqset_iter = imap_search_seqset_iter_init(search_args, status.messages,
+						   IMAP_EXPUNGE_BATCH_SIZE);
+
+	do {
+		struct mailbox_transaction_context *t;
+		struct mail_search_context *ctx;
+		struct mail *mail;
+
+		t = mailbox_transaction_begin(box, 0, "EXPUNGE");
+		ctx = mailbox_search_init(t, search_args, NULL, 0, NULL);
+
+		while (mailbox_search_next(ctx, &mail)) {
+			*expunged_count += 1;
+			mail_expunge(mail);
+			expunges = TRUE;
+		}
+
+		ret = mailbox_search_deinit(&ctx);
+		if (ret < 0) {
+			mailbox_transaction_rollback(&t);
+			break;
+		} else {
+			ret = mailbox_transaction_commit(&t);
+			if (ret < 0)
+				break;
+		}
+	} while (imap_search_seqset_iter_next(seqset_iter));
+
+	imap_search_seqset_iter_deinit(&seqset_iter);
+	mail_search_args_unref(&search_args);
+
+	if (ret < 0)
+		return ret;
+
+	return expunges ? 1 : 0;
+}
diff --git a/src/imap/imap-expunge.h b/src/imap/imap-expunge.h
new file mode 100644
index 0000000..e5b3825
--- /dev/null
+++ b/src/imap/imap-expunge.h
@@ -0,0 +1,10 @@
+#ifndef IMAP_EXPUNGE_H
+#define IMAP_EXPUNGE_H
+
+struct mail_search_arg;
+
+int imap_expunge(struct mailbox *box, struct mail_search_arg *next_search_arg,
+		 unsigned int *expunged_count)
+	ATTR_NULL(2);
+
+#endif
diff --git a/src/imap/imap-feature.c b/src/imap/imap-feature.c
new file mode 100644
index 0000000..d8d52b8
--- /dev/null
+++ b/src/imap/imap-feature.c
@@ -0,0 +1,46 @@
+/* Copyright (c) 2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "imap-feature.h"
+
+static ARRAY_TYPE(imap_feature) feature_register = ARRAY_INIT;
+
+bool imap_feature_lookup(const char *name, unsigned int *feature_idx_r)
+{
+	for (unsigned int idx = 0; idx < array_count(&feature_register); idx++) {
+		const struct imap_feature *feat =
+			array_idx(&feature_register, idx);
+		if (strcasecmp(name, feat->feature) == 0) {
+			*feature_idx_r = idx;
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+const struct imap_feature *imap_feature_idx(unsigned int feature_idx)
+{
+	return array_idx(&feature_register, feature_idx);
+}
+
+unsigned int
+imap_feature_register(const char *feature, enum mailbox_feature mailbox_features,
+		      imap_client_enable_callback_t *callback)
+{
+	struct imap_feature *feat = array_append_space(&feature_register);
+	feat->feature = feature;
+	feat->mailbox_features = mailbox_features;
+	feat->callback = callback;
+	return array_count(&feature_register)-1;
+}
+
+void imap_features_init(void)
+{
+	i_assert(!array_is_created(&feature_register));
+	i_array_init(&feature_register, 8);
+}
+
+void imap_features_deinit(void)
+{
+	array_free(&feature_register);
+}
diff --git a/src/imap/imap-feature.h b/src/imap/imap-feature.h
new file mode 100644
index 0000000..a96aa6e
--- /dev/null
+++ b/src/imap/imap-feature.h
@@ -0,0 +1,24 @@
+#ifndef IMAP_FEATURE_H
+#define IMAP_FEATURE_H
+
+typedef void imap_client_enable_callback_t(struct client *);
+
+struct imap_feature {
+	const char *feature;
+	enum mailbox_feature mailbox_features;
+	imap_client_enable_callback_t *callback;
+	bool enabled;
+};
+ARRAY_DEFINE_TYPE(imap_feature, struct imap_feature);
+
+bool imap_feature_lookup(const char *name, unsigned int *feature_idx_r);
+const struct imap_feature *imap_feature_idx(unsigned int feature_idx);
+
+unsigned int
+imap_feature_register(const char *feature, enum mailbox_feature mailbox_features,
+		      imap_client_enable_callback_t *callback);
+
+void imap_features_init(void);
+void imap_features_deinit(void);
+
+#endif
diff --git a/src/imap/imap-fetch-body.c b/src/imap/imap-fetch-body.c
new file mode 100644
index 0000000..b467334
--- /dev/null
+++ b/src/imap/imap-fetch-body.c
@@ -0,0 +1,722 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "buffer.h"
+#include "str.h"
+#include "strescape.h"
+#include "istream.h"
+#include "ostream.h"
+#include "istream-header-filter.h"
+#include "message-parser.h"
+#include "mail-storage-private.h"
+#include "imap-quote.h"
+#include "imap-parser.h"
+#include "imap-msgpart.h"
+#include "imap-fetch.h"
+
+#include <ctype.h>
+#include <unistd.h>
+
+struct imap_fetch_body_data {
+	const char *section; /* NOTE: always uppercased */
+	struct imap_msgpart *msgpart;
+
+	bool partial:1;
+	bool binary:1;
+	bool binary_size:1;
+};
+
+struct imap_fetch_preview_data {
+	/* If TRUE, lazy modifier is specified. */
+	bool lazy:1;
+	/* Uses the pre-RFC 8970 standard (requires algorithm to be returned
+	 * as part of FETCH response). */
+	bool old_standard:1;
+	/* If TRUE, uses "PREVIEW" command; if FALSE, uses older "SNIPPET"
+	 * command. */
+	bool preview_cmd:1;
+};
+
+static void fetch_read_error(struct imap_fetch_context *ctx,
+			     const char **disconnect_reason_r)
+{
+	struct imap_fetch_state *state = &ctx->state;
+
+	if (state->cur_input->stream_errno == ENOENT) {
+		if (state->cur_mail->expunged) {
+			*disconnect_reason_r = "Mail expunged while it was being FETCHed";
+			return;
+		}
+	}
+	mail_set_critical(state->cur_mail,
+		"read(%s) failed: %s (FETCH %s)",
+		i_stream_get_name(state->cur_input),
+		i_stream_get_error(state->cur_input),
+		state->cur_human_name);
+	*disconnect_reason_r = "FETCH read() failed";
+}
+
+static const char *get_body_name(const struct imap_fetch_body_data *body)
+{
+	string_t *str;
+
+	str = t_str_new(128);
+	if (body->binary_size)
+		str_append(str, "BINARY.SIZE");
+	else if (body->binary)
+		str_append(str, "BINARY");
+	else
+		str_append(str, "BODY");
+	str_printfa(str, "[%s]", body->section);
+	if (body->partial) {
+		str_printfa(str, "<%"PRIuUOFF_T">",
+			    imap_msgpart_get_partial_offset(body->msgpart));
+	}
+	return str_c(str);
+}
+
+static string_t *get_prefix(struct imap_fetch_state *state,
+			    const struct imap_fetch_body_data *body,
+			    uoff_t size, bool has_nuls)
+{
+	string_t *str;
+
+	str = t_str_new(128);
+	if (state->cur_first)
+		state->cur_first = FALSE;
+	else
+		str_append_c(str, ' ');
+
+	str_append(str, get_body_name(body));
+
+	if (size == UOFF_T_MAX)
+		str_append(str, " NIL");
+	else if (has_nuls && body->binary)
+		str_printfa(str, " ~{%"PRIuUOFF_T"}\r\n", size);
+	else
+		str_printfa(str, " {%"PRIuUOFF_T"}\r\n", size);
+	return str;
+}
+
+static int fetch_stream_continue(struct imap_fetch_context *ctx)
+{
+	struct imap_fetch_state *state = &ctx->state;
+	const char *disconnect_reason;
+	uoff_t orig_input_offset = state->cur_input->v_offset;
+	enum ostream_send_istream_result res;
+
+	o_stream_set_max_buffer_size(ctx->client->output, 0);
+	res = o_stream_send_istream(ctx->client->output, state->cur_input);
+	o_stream_set_max_buffer_size(ctx->client->output, SIZE_MAX);
+
+	if (ctx->state.cur_stats_sizep != NULL) {
+		*ctx->state.cur_stats_sizep +=
+			state->cur_input->v_offset - orig_input_offset;
+	}
+
+	switch (res) {
+	case OSTREAM_SEND_ISTREAM_RESULT_FINISHED:
+		if (state->cur_input->v_offset != state->cur_size) {
+			/* Input stream gave less data than expected */
+			mail_set_cache_corrupted(state->cur_mail,
+				state->cur_size_field, t_strdup_printf(
+				"read(%s): FETCH %s got too little data: "
+				"%"PRIuUOFF_T" vs %"PRIuUOFF_T,
+				i_stream_get_name(state->cur_input),
+				state->cur_human_name,
+				state->cur_input->v_offset, state->cur_size));
+			client_disconnect(ctx->client, "FETCH failed");
+			return -1;
+		}
+		return 1;
+	case OSTREAM_SEND_ISTREAM_RESULT_WAIT_INPUT:
+		i_unreached();
+	case OSTREAM_SEND_ISTREAM_RESULT_WAIT_OUTPUT:
+		return 0;
+	case OSTREAM_SEND_ISTREAM_RESULT_ERROR_INPUT:
+		fetch_read_error(ctx, &disconnect_reason);
+		client_disconnect(ctx->client, disconnect_reason);
+		return -1;
+	case OSTREAM_SEND_ISTREAM_RESULT_ERROR_OUTPUT:
+		/* client disconnected */
+		return -1;
+	}
+	i_unreached();
+}
+
+static const char *
+get_body_human_name(pool_t pool, struct imap_fetch_body_data *body)
+{
+	string_t *str;
+	uoff_t partial_offset, partial_size;
+
+	str = t_str_new(64);
+	if (body->binary)
+		str_append(str, "BINARY[");
+	else
+		str_append(str, "BODY[");
+	str_append(str, body->section);
+	str_append_c(str, ']');
+
+	partial_offset = imap_msgpart_get_partial_offset(body->msgpart);
+	partial_size = imap_msgpart_get_partial_size(body->msgpart);
+	if (partial_offset != 0 || partial_size != UOFF_T_MAX) {
+		str_printfa(str, "<%"PRIuUOFF_T, partial_offset);
+		if (partial_size != UOFF_T_MAX)
+			str_printfa(str, ".%"PRIuUOFF_T, partial_size);
+		str_append_c(str, '>');
+	}
+	return p_strdup(pool, str_c(str));
+}
+
+static void fetch_state_update_stats(struct imap_fetch_context *ctx,
+				     const struct imap_msgpart *msgpart)
+{
+	if (!imap_msgpart_contains_body(msgpart)) {
+		ctx->client->fetch_hdr_count++;
+		ctx->state.cur_stats_sizep = &ctx->client->fetch_hdr_bytes;
+	} else {
+		ctx->client->fetch_body_count++;
+		ctx->state.cur_stats_sizep = &ctx->client->fetch_body_bytes;
+	}
+}
+
+static int fetch_body_msgpart(struct imap_fetch_context *ctx, struct mail *mail,
+			      struct imap_fetch_body_data *body)
+{
+	struct imap_msgpart_open_result result;
+	string_t *str;
+
+	if (mail == NULL) {
+		imap_msgpart_free(&body->msgpart);
+		return 1;
+	}
+
+	if (imap_msgpart_open(mail, body->msgpart, &result) < 0)
+		return -1;
+	i_assert(result.input->v_offset == 0);
+	ctx->state.cur_input = result.input;
+	ctx->state.cur_size = result.size;
+	ctx->state.cur_size_field = result.size_field;
+	ctx->state.cur_human_name = get_body_human_name(ctx->ctx_pool, body);
+
+	fetch_state_update_stats(ctx, body->msgpart);
+	str = get_prefix(&ctx->state, body, ctx->state.cur_size,
+			 result.binary_decoded_input_has_nuls);
+	o_stream_nsend(ctx->client->output, str_data(str), str_len(str));
+
+	ctx->state.cont_handler = fetch_stream_continue;
+	return ctx->state.cont_handler(ctx);
+}
+
+static int fetch_binary_size(struct imap_fetch_context *ctx, struct mail *mail,
+			     struct imap_fetch_body_data *body)
+{
+	string_t *str;
+	uoff_t size;
+
+	if (mail == NULL) {
+		imap_msgpart_free(&body->msgpart);
+		return 1;
+	}
+
+	if (imap_msgpart_size(mail, body->msgpart, &size) < 0)
+		return -1;
+
+	str = t_str_new(128);
+	if (ctx->state.cur_first)
+		ctx->state.cur_first = FALSE;
+	else
+		str_append_c(str, ' ');
+	str_printfa(str, "%s %"PRIuUOFF_T, get_body_name(body), size);
+
+	if (o_stream_send(ctx->client->output, str_data(str), str_len(str)) < 0)
+		return -1;
+	return 1;
+}
+
+/* Parse next digits in string into integer. Returns -1 if the integer
+   becomes too big and wraps. */
+static int read_uoff_t(const char **p, uoff_t *value)
+{
+	return str_parse_uoff(*p, value, p);
+}
+
+static int
+body_header_fields_parse(struct imap_fetch_init_context *ctx,
+			 struct imap_fetch_body_data *body, const char *prefix,
+			 const struct imap_arg *args, unsigned int args_count)
+{
+	string_t *str;
+	const char *value;
+	size_t i;
+
+	ctx->fetch_ctx->fetch_header_fields = TRUE;
+
+	str = str_new(ctx->pool, 128);
+	str_append(str, prefix);
+	str_append(str, " (");
+
+	for (i = 0; i < args_count; i++) {
+		if (!imap_arg_get_astring(&args[i], &value)) {
+			ctx->error = "Invalid BODY[..] parameter: "
+				"Header list contains non-strings";
+			return -1;
+		}
+		value = t_str_ucase(value);
+
+		if (i != 0)
+			str_append_c(str, ' ');
+
+		if (args[i].type == IMAP_ARG_ATOM)
+			str_append(str, value);
+		else
+			imap_append_quoted(str, value);
+	}
+	str_append_c(str, ')');
+	body->section = str_c(str);
+	return 0;
+}
+
+static int body_parse_partial(struct imap_fetch_body_data *body,
+			      const char *p, const char **error_r)
+{
+	uoff_t offset, size = UOFF_T_MAX;
+
+	if (*p == '\0')
+		return 0;
+	/* <start.end> */
+	if (*p != '<') {
+		*error_r = "Unexpected data after ']'";
+		return -1;
+	}
+
+	p++;
+	body->partial = TRUE;
+
+	if (read_uoff_t(&p, &offset) < 0 || offset > OFF_T_MAX) {
+		/* wrapped */
+		*error_r = "Too big partial start";
+		return -1;
+	}
+
+	if (*p == '.') {
+		p++;
+		if (read_uoff_t(&p, &size) < 0 || size > OFF_T_MAX) {
+			/* wrapped */
+			*error_r = "Too big partial end";
+			return -1;
+		}
+	}
+
+	if (*p != '>') {
+		*error_r = "Missing '>' in partial";
+		return -1;
+	}
+	if (p[1] != '\0') {
+		*error_r = "Unexpected data after '>'";
+		return -1;
+	}
+	imap_msgpart_set_partial(body->msgpart, offset, size);
+	return 0;
+}
+
+bool imap_fetch_body_section_init(struct imap_fetch_init_context *ctx)
+{
+	struct imap_fetch_body_data *body;
+	const struct imap_arg *list_args;
+	unsigned int list_count;
+	const char *str, *p, *error;
+
+	i_assert(str_begins(ctx->name, "BODY"));
+	p = ctx->name + 4;
+
+	body = p_new(ctx->pool, struct imap_fetch_body_data, 1);
+
+	if (str_begins(p, ".PEEK"))
+		p += 5;
+	else
+		ctx->fetch_ctx->flags_update_seen = TRUE;
+	if (*p != '[') {
+		ctx->error = "Invalid BODY[..] parameter: Missing '['";
+		return FALSE;
+	}
+
+	if (imap_arg_get_list_full(&ctx->args[0], &list_args, &list_count)) {
+		/* BODY[HEADER.FIELDS.. (headers list)] */
+		if (!imap_arg_get_atom(&ctx->args[1], &str) ||
+		    str[0] != ']') {
+			ctx->error = "Invalid BODY[..] parameter: Missing ']'";
+			return FALSE;
+		}
+		if (body_header_fields_parse(ctx, body, p+1,
+					     list_args, list_count) < 0)
+			return FALSE;
+		p = str+1;
+		ctx->args += 2;
+	} else {
+		/* no headers list */
+		body->section = p+1;
+		p = strchr(body->section, ']');
+		if (p == NULL) {
+			ctx->error = "Invalid BODY[..] parameter: Missing ']'";
+			return FALSE;
+		}
+		body->section = p_strdup_until(ctx->pool, body->section, p);
+		p++;
+	}
+	if (imap_msgpart_parse(body->section, &body->msgpart) < 0) {
+		ctx->error = "Invalid BODY[..] section";
+		return FALSE;
+	}
+	ctx->fetch_ctx->fetch_data |=
+		imap_msgpart_get_fetch_data(body->msgpart);
+	imap_msgpart_get_wanted_headers(body->msgpart, &ctx->fetch_ctx->all_headers);
+
+	if (body_parse_partial(body, p, &error) < 0) {
+		ctx->error = p_strdup_printf(ctx->pool,
+			"Invalid BODY[..] parameter: %s", error);
+		return FALSE;
+	}
+
+	/* update the section name for the imap_fetch_add_handler() */
+	ctx->name = p_strdup(ctx->pool, get_body_name(body));
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_WANT_DEINIT,
+			       "NIL", fetch_body_msgpart, body);
+	return TRUE;
+}
+
+bool imap_fetch_binary_init(struct imap_fetch_init_context *ctx)
+{
+	struct imap_fetch_body_data *body;
+	const struct imap_arg *list_args;
+	unsigned int list_count;
+	const char *str, *p, *error;
+
+	i_assert(str_begins(ctx->name, "BINARY"));
+	p = ctx->name + 6;
+
+	body = p_new(ctx->pool, struct imap_fetch_body_data, 1);
+	body->binary = TRUE;
+
+	if (str_begins(p, ".SIZE")) {
+		/* fetch decoded size of the section */
+		p += 5;
+		body->binary_size = TRUE;
+	} else if (str_begins(p, ".PEEK")) {
+		p += 5;
+	} else {
+		ctx->fetch_ctx->flags_update_seen = TRUE;
+	}
+	if (*p != '[') {
+		ctx->error = "Invalid BINARY[..] parameter: Missing '['";
+		return FALSE;
+	}
+
+	if (imap_arg_get_list_full(&ctx->args[0], &list_args, &list_count)) {
+		/* BINARY[HEADER.FIELDS.. (headers list)] */
+		if (!imap_arg_get_atom(&ctx->args[1], &str) ||
+		    str[0] != ']') {
+			ctx->error = "Invalid BINARY[..] parameter: Missing ']'";
+			return FALSE;
+		}
+		if (body_header_fields_parse(ctx, body, p+1,
+					     list_args, list_count) < 0)
+			return FALSE;
+		p = str+1;
+		ctx->args += 2;
+	} else {
+		/* no headers list */
+		body->section = p+1;
+		p = strchr(body->section, ']');
+		if (p == NULL) {
+			ctx->error = "Invalid BINARY[..] parameter: Missing ']'";
+			return FALSE;
+		}
+		body->section = p_strdup_until(ctx->pool, body->section, p);
+		p++;
+	}
+	if (imap_msgpart_parse(body->section, &body->msgpart) < 0) {
+		ctx->error = "Invalid BINARY[..] section";
+		return FALSE;
+	}
+	imap_msgpart_set_decode_to_binary(body->msgpart);
+	ctx->fetch_ctx->fetch_data |=
+		imap_msgpart_get_fetch_data(body->msgpart);
+
+	if (!body->binary_size) {
+		if (body_parse_partial(body, p, &error) < 0) {
+			ctx->error = p_strdup_printf(ctx->pool,
+				"Invalid BINARY[..] parameter: %s", error);
+			return FALSE;
+		}
+	}
+
+	/* update the section name for the imap_fetch_add_handler() */
+	ctx->name = p_strdup(ctx->pool, get_body_name(body));
+	if (body->binary_size) {
+		imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_WANT_DEINIT,
+				       "0", fetch_binary_size, body);
+	} else {
+		imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_WANT_DEINIT,
+				       "NIL", fetch_body_msgpart, body);
+	}
+	return TRUE;
+}
+
+static int ATTR_NULL(3)
+fetch_rfc822_size(struct imap_fetch_context *ctx, struct mail *mail,
+		  void *context ATTR_UNUSED)
+{
+	uoff_t size;
+
+	if (mail_get_virtual_size(mail, &size) < 0)
+		return -1;
+
+	str_printfa(ctx->state.cur_str, "RFC822.SIZE %"PRIuUOFF_T" ", size);
+	return 1;
+}
+
+static int
+fetch_and_free_msgpart(struct imap_fetch_context *ctx,
+		       struct mail *mail, struct imap_msgpart **_msgpart)
+{
+	struct imap_msgpart_open_result result;
+	int ret;
+
+	ret = imap_msgpart_open(mail, *_msgpart, &result);
+	imap_msgpart_free(_msgpart);
+	if (ret < 0)
+		return -1;
+	i_assert(result.input->v_offset == 0);
+	ctx->state.cur_input = result.input;
+	ctx->state.cur_size = result.size;
+	ctx->state.cur_size_field = result.size_field;
+	ctx->state.cont_handler = fetch_stream_continue;
+	return 0;
+}
+
+static int ATTR_NULL(3)
+fetch_rfc822(struct imap_fetch_context *ctx, struct mail *mail,
+	     void *context ATTR_UNUSED)
+{
+	struct imap_msgpart *msgpart;
+	const char *str;
+
+	msgpart = imap_msgpart_full();
+	fetch_state_update_stats(ctx, msgpart);
+	if (fetch_and_free_msgpart(ctx, mail, &msgpart) < 0)
+		return -1;
+
+	str = t_strdup_printf(" RFC822 {%"PRIuUOFF_T"}\r\n",
+			      ctx->state.cur_size);
+	if (ctx->state.cur_first) {
+		str++; ctx->state.cur_first = FALSE;
+	}
+	o_stream_nsend_str(ctx->client->output, str);
+
+	ctx->state.cur_human_name = "RFC822";
+	return ctx->state.cont_handler(ctx);
+}
+
+static int ATTR_NULL(3)
+fetch_rfc822_header(struct imap_fetch_context *ctx,
+		    struct mail *mail, void *context ATTR_UNUSED)
+{
+	struct imap_msgpart *msgpart;
+	const char *str;
+
+	msgpart = imap_msgpart_header();
+	fetch_state_update_stats(ctx, msgpart);
+	if (fetch_and_free_msgpart(ctx, mail, &msgpart) < 0)
+		return -1;
+
+	str = t_strdup_printf(" RFC822.HEADER {%"PRIuUOFF_T"}\r\n",
+			      ctx->state.cur_size);
+	if (ctx->state.cur_first) {
+		str++; ctx->state.cur_first = FALSE;
+	}
+	o_stream_nsend_str(ctx->client->output, str);
+
+	ctx->state.cur_human_name = "RFC822.HEADER";
+	return ctx->state.cont_handler(ctx);
+}
+
+static int ATTR_NULL(3)
+fetch_rfc822_text(struct imap_fetch_context *ctx, struct mail *mail,
+		  void *context ATTR_UNUSED)
+{
+	struct imap_msgpart *msgpart;
+	const char *str;
+
+	msgpart = imap_msgpart_body();
+	fetch_state_update_stats(ctx, msgpart);
+	if (fetch_and_free_msgpart(ctx, mail, &msgpart) < 0)
+		return -1;
+
+	str = t_strdup_printf(" RFC822.TEXT {%"PRIuUOFF_T"}\r\n",
+			      ctx->state.cur_size);
+	if (ctx->state.cur_first) {
+		str++; ctx->state.cur_first = FALSE;
+	}
+	o_stream_nsend_str(ctx->client->output, str);
+
+	ctx->state.cur_human_name = "RFC822.TEXT";
+	return ctx->state.cont_handler(ctx);
+}
+
+bool imap_fetch_rfc822_init(struct imap_fetch_init_context *ctx)
+{
+	const char *name = ctx->name;
+
+	if (name[6] == '\0') {
+		ctx->fetch_ctx->fetch_data |= MAIL_FETCH_STREAM_HEADER |
+			MAIL_FETCH_STREAM_BODY;
+		ctx->fetch_ctx->flags_update_seen = TRUE;
+		imap_fetch_add_handler(ctx, 0, "NIL",
+				       fetch_rfc822, NULL);
+		return TRUE;
+	}
+
+	if (strcmp(name+6, ".SIZE") == 0) {
+		ctx->fetch_ctx->fetch_data |= MAIL_FETCH_VIRTUAL_SIZE;
+		imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+				       "0", fetch_rfc822_size, NULL);
+		return TRUE;
+	}
+	if (strcmp(name+6, ".HEADER") == 0) {
+		ctx->fetch_ctx->fetch_data |= MAIL_FETCH_STREAM_HEADER;
+		imap_fetch_add_handler(ctx, 0, "NIL",
+				       fetch_rfc822_header, NULL);
+		return TRUE;
+	}
+	if (strcmp(name+6, ".TEXT") == 0) {
+		ctx->fetch_ctx->fetch_data |= MAIL_FETCH_STREAM_BODY;
+		ctx->fetch_ctx->flags_update_seen = TRUE;
+		imap_fetch_add_handler(ctx, 0, "NIL",
+				       fetch_rfc822_text, NULL);
+		return TRUE;
+	}
+
+	ctx->error = t_strconcat("Unknown parameter ", name, NULL);
+	return FALSE;
+}
+
+static int ATTR_NULL(3)
+fetch_snippet(struct imap_fetch_context *ctx, struct mail *mail,
+	      struct imap_fetch_preview_data *preview)
+{
+	enum mail_lookup_abort temp_lookup_abort = preview->lazy ? MAIL_LOOKUP_ABORT_NOT_IN_CACHE_START_CACHING : mail->lookup_abort;
+	enum mail_lookup_abort orig_lookup_abort = mail->lookup_abort;
+	const char *resp, *snippet;
+	int ret;
+
+	mail->lookup_abort = temp_lookup_abort;
+	ret = mail_get_special(mail, MAIL_FETCH_BODY_SNIPPET, &snippet);
+	mail->lookup_abort = orig_lookup_abort;
+
+	resp = preview->preview_cmd ? "PREVIEW" : "SNIPPET";
+
+	if (ret == 0) {
+		/* got it => nothing to do */
+		snippet++; /* skip over snippet version byte */
+	} else if (mailbox_get_last_mail_error(mail->box) != MAIL_ERROR_LOOKUP_ABORTED) {
+		/* actual error => bail */
+		return -1;
+	} else {
+		/*
+		 * Two ways to get here:
+		 * - not in cache && lazy => give up
+		 * - not in cache && !lazy => someone higher up set
+		 *   MAIL_LOOKUP_ABORT_NOT_IN_CACHE and so even though we got
+		 *   a non-lazy request we failed the cache lookup.
+		 *
+		 *   This is not an error, but since the scenario is
+		 *   sufficiently convoluted this else branch serves to
+		 *   document it.
+		 *
+		 * This path will return NIL as the preview response.
+		 */
+	}
+
+	str_append(ctx->state.cur_str, resp);
+	if (preview->old_standard)
+		str_append(ctx->state.cur_str, " (FUZZY ");
+	else
+		str_append(ctx->state.cur_str, " ");
+	if (ret == 0)
+		imap_append_string(ctx->state.cur_str, snippet);
+	else
+		str_append(ctx->state.cur_str, "NIL");
+	if (preview->old_standard)
+		str_append(ctx->state.cur_str, ")");
+	str_append_c(ctx->state.cur_str, ' ');
+
+	return 1;
+}
+
+static bool fetch_preview_init(struct imap_fetch_init_context *ctx,
+			       bool preview_cmd)
+{
+	const struct imap_arg *list_args;
+	unsigned int list_count;
+	struct imap_fetch_preview_data *preview;
+
+	preview = p_new(ctx->pool, struct imap_fetch_preview_data, 1);
+	preview->preview_cmd = preview_cmd;
+	/* We can tell we are using the "Old" (pre-RFC 8970) standard
+	 * if:
+	 * 1) SNIPPET command is used
+	 * 2) FUZZY algorithm is explicitly requested
+	 * The one usage we cannot catch is if PREVIEW command is used, and
+	 * no algorithm is specified - the pre-RFC standard requires that the
+	 * algorithm must be output as part of the response; the RFC standard
+	 * does not output the algorithm. There is unfortunately nothing we
+	 * can do about this, so we need to send the standards compliant
+	 * way. */
+	preview->old_standard = !preview_cmd;
+
+	if (imap_arg_get_list_full(&ctx->args[0], &list_args, &list_count)) {
+		unsigned int i;
+
+		for (i = 0; i < list_count; i++) {
+			const char *str;
+
+			if (!imap_arg_get_atom(&list_args[i], &str)) {
+				ctx->error = "Invalid PREVIEW modifier";
+				return FALSE;
+			}
+
+			if (strcasecmp(str, "LAZY") == 0) {
+				preview->lazy = TRUE;
+			} else if (strcasecmp(str, "LAZY=FUZZY") == 0) {
+				preview->lazy = TRUE;
+				preview->old_standard = TRUE;
+			} else if (strcasecmp(str, "FUZZY") == 0) {
+				preview->old_standard = TRUE;
+			} else {
+				ctx->error = t_strdup_printf("'%s' is not a "
+							     "supported PREVIEW modifier",
+							     str);
+				return FALSE;
+			}
+		}
+
+		ctx->args += list_count;
+	}
+
+	ctx->fetch_ctx->fetch_data |= MAIL_FETCH_BODY_SNIPPET;
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       "NIL", fetch_snippet, preview);
+	return TRUE;
+}
+
+bool imap_fetch_preview_init(struct imap_fetch_init_context *ctx)
+{
+	return fetch_preview_init(ctx, TRUE);
+}
+
+bool imap_fetch_snippet_init(struct imap_fetch_init_context *ctx)
+{
+	return fetch_preview_init(ctx, FALSE);
+}
diff --git a/src/imap/imap-fetch.c b/src/imap/imap-fetch.c
new file mode 100644
index 0000000..db811f7
--- /dev/null
+++ b/src/imap/imap-fetch.c
@@ -0,0 +1,1040 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "array.h"
+#include "buffer.h"
+#include "istream.h"
+#include "ostream.h"
+#include "str.h"
+#include "message-size.h"
+#include "imap-date.h"
+#include "imap-utf7.h"
+#include "mail-search-build.h"
+#include "imap-commands.h"
+#include "imap-quote.h"
+#include "imap-fetch.h"
+#include "imap-util.h"
+
+#include <ctype.h>
+
+#define BODY_NIL_REPLY \
+	"\"text\" \"plain\" NIL NIL NIL \"7bit\" 0 0"
+#define ENVELOPE_NIL_REPLY \
+	"(NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL)"
+
+static ARRAY(struct imap_fetch_handler) fetch_handlers;
+
+static int imap_fetch_handler_cmp(const struct imap_fetch_handler *h1,
+				  const struct imap_fetch_handler *h2)
+{
+	return strcmp(h1->name, h2->name);
+}
+
+void imap_fetch_handlers_register(const struct imap_fetch_handler *handlers,
+				  size_t count)
+{
+	array_append(&fetch_handlers, handlers, count);
+	array_sort(&fetch_handlers, imap_fetch_handler_cmp);
+}
+
+void imap_fetch_handler_unregister(const char *name)
+{
+	const struct imap_fetch_handler *handler, *first_handler;
+
+	first_handler = array_front(&fetch_handlers);
+	handler = imap_fetch_handler_lookup(name);
+	i_assert(handler != NULL);
+	array_delete(&fetch_handlers, handler - first_handler, 1);
+}
+
+static int
+imap_fetch_handler_bsearch(const char *name, const struct imap_fetch_handler *h)
+{
+	return strcmp(name, h->name);
+}
+
+const struct imap_fetch_handler *imap_fetch_handler_lookup(const char *name)
+{
+	return array_bsearch(&fetch_handlers, name, imap_fetch_handler_bsearch);
+}
+
+bool imap_fetch_init_handler(struct imap_fetch_init_context *init_ctx)
+{
+	const struct imap_fetch_handler *handler;
+	const char *lookup_name, *p;
+
+	for (p = init_ctx->name; i_isalnum(*p) || *p == '-'; p++) ;
+	lookup_name = t_strdup_until(init_ctx->name, p);
+
+	handler = array_bsearch(&fetch_handlers, lookup_name,
+				imap_fetch_handler_bsearch);
+	if (handler == NULL) {
+		init_ctx->error = t_strdup_printf("Unknown parameter: %s",
+						  init_ctx->name);
+		return FALSE;
+	}
+	if (!handler->init(init_ctx)) {
+		i_assert(init_ctx->error != NULL);
+		return FALSE;
+	}
+	return TRUE;
+}
+
+void imap_fetch_init_nofail_handler(struct imap_fetch_context *ctx,
+				    bool (*init)(struct imap_fetch_init_context *))
+{
+	struct imap_fetch_init_context init_ctx;
+
+	i_zero(&init_ctx);
+	init_ctx.fetch_ctx = ctx;
+	init_ctx.pool = ctx->ctx_pool;
+
+	if (!init(&init_ctx))
+		i_unreached();
+}
+
+int imap_fetch_att_list_parse(struct client *client, pool_t pool,
+			      const struct imap_arg *list,
+			      struct imap_fetch_context **fetch_ctx_r,
+			      const char **client_error_r)
+{
+	struct imap_fetch_init_context init_ctx;
+	const char *str;
+
+	i_zero(&init_ctx);
+	init_ctx.fetch_ctx = imap_fetch_alloc(client, pool, "NOTIFY");
+	init_ctx.pool = pool;
+	init_ctx.args = list;
+
+	while (imap_arg_get_atom(init_ctx.args, &str)) {
+		init_ctx.name = t_str_ucase(str);
+		init_ctx.args++;
+		if (!imap_fetch_init_handler(&init_ctx)) {
+			*client_error_r = t_strconcat("Invalid fetch-att list: ",
+						      init_ctx.error, NULL);
+			imap_fetch_free(&init_ctx.fetch_ctx);
+			return -1;
+		}
+	}
+	if (!IMAP_ARG_IS_EOL(init_ctx.args)) {
+		*client_error_r = "fetch-att list contains non-atoms.";
+		imap_fetch_free(&init_ctx.fetch_ctx);
+		return -1;
+	}
+	*fetch_ctx_r = init_ctx.fetch_ctx;
+	return 0;
+}
+
+struct imap_fetch_context *
+imap_fetch_alloc(struct client *client, pool_t pool, const char *reason)
+{
+	struct imap_fetch_context *ctx;
+
+	ctx = p_new(pool, struct imap_fetch_context, 1);
+	ctx->client = client;
+	ctx->ctx_pool = pool;
+	ctx->reason = p_strdup(pool, reason);
+	pool_ref(pool);
+
+	p_array_init(&ctx->all_headers, pool, 64);
+	p_array_init(&ctx->handlers, pool, 16);
+	p_array_init(&ctx->tmp_keywords, pool,
+		     client->keywords.announce_count + 8);
+	return ctx;
+}
+
+#undef imap_fetch_add_handler
+void imap_fetch_add_handler(struct imap_fetch_init_context *ctx,
+			    enum imap_fetch_handler_flags flags,
+			    const char *nil_reply,
+			    imap_fetch_handler_t *handler, void *context)
+{
+	/* partially because of broken clients, but also partially because
+	   it potentially can make client implementations faster, we have a
+	   buffered parameter which basically means that the handler promises
+	   to write the output in fetch_ctx->state.cur_str. The cur_str is then
+	   sent to client before calling any non-buffered handlers.
+
+	   We try to keep the handler registration order the same as the
+	   client requested them. This is especially useful to get UID
+	   returned first, which some clients rely on..
+	*/
+	const struct imap_fetch_context_handler *ctx_handler;
+	struct imap_fetch_context_handler h;
+
+	if (context == NULL) {
+		/* don't allow duplicate handlers */
+		array_foreach(&ctx->fetch_ctx->handlers, ctx_handler) {
+			if (ctx_handler->handler == handler &&
+			    ctx_handler->context == NULL)
+				return;
+		}
+	}
+
+	i_zero(&h);
+	h.handler = handler;
+	h.context = context;
+	h.buffered = (flags & IMAP_FETCH_HANDLER_FLAG_BUFFERED) != 0;
+	h.want_deinit = (flags & IMAP_FETCH_HANDLER_FLAG_WANT_DEINIT) != 0;
+	h.name = p_strdup(ctx->pool, ctx->name);
+	h.nil_reply = p_strdup(ctx->pool, nil_reply);
+
+	if (!h.buffered)
+		array_push_back(&ctx->fetch_ctx->handlers, &h);
+	else {
+		array_insert(&ctx->fetch_ctx->handlers,
+			     ctx->fetch_ctx->buffered_handlers_count, &h, 1);
+                ctx->fetch_ctx->buffered_handlers_count++;
+	}
+}
+
+static void
+expunges_drop_known(struct mailbox *box,
+		    const struct imap_fetch_qresync_args *qresync_args,
+		    struct mailbox_transaction_context *trans,
+		    ARRAY_TYPE(seq_range) *expunged_uids)
+{
+	struct mailbox_status status;
+	struct mail *mail;
+	const uint32_t *seqs, *uids;
+	unsigned int i, count;
+
+	seqs = array_get(qresync_args->qresync_sample_seqset, &count);
+	uids = array_front(qresync_args->qresync_sample_uidset);
+	i_assert(array_count(qresync_args->qresync_sample_uidset) == count);
+	i_assert(count > 0);
+
+	mailbox_get_open_status(box, STATUS_MESSAGES, &status);
+	mail = mail_alloc(trans, 0, NULL);
+
+	/* FIXME: we could do removals from the middle as well */
+	for (i = 0; i < count && seqs[i] <= status.messages; i++) {
+		mail_set_seq(mail, seqs[i]);
+		if (uids[i] != mail->uid)
+			break;
+	}
+	if (i > 0)
+		seq_range_array_remove_range(expunged_uids, 1, uids[i-1]);
+	mail_free(&mail);
+}
+
+static int
+get_expunges_fallback(struct mailbox *box,
+		      const struct imap_fetch_qresync_args *qresync_args,
+		      const ARRAY_TYPE(seq_range) *uid_filter_arr,
+		      ARRAY_TYPE(seq_range) *expunged_uids)
+{
+	struct mailbox_transaction_context *trans;
+	struct mail_search_args *search_args;
+	struct mail_search_context *search_ctx;
+	struct mail *mail;
+	const struct seq_range *uid_filter;
+	struct mailbox_status status;
+	unsigned int i, count;
+	uint32_t next_uid;
+	int ret = 0;
+
+	uid_filter = array_get(uid_filter_arr, &count);
+	i_assert(count > 0);
+	i = 0;
+	next_uid = uid_filter[0].seq1;
+
+	/* search UIDs only in given range */
+	search_args = mail_search_build_init();
+	search_args->args = p_new(search_args->pool, struct mail_search_arg, 1);
+	search_args->args->type = SEARCH_UIDSET;
+	p_array_init(&search_args->args->value.seqset, search_args->pool, count);
+	array_append_array(&search_args->args->value.seqset, uid_filter_arr);
+
+	trans = mailbox_transaction_begin(box, 0, "FETCH send VANISHED");
+	search_ctx = mailbox_search_init(trans, search_args, NULL, 0, NULL);
+	mail_search_args_unref(&search_args);
+
+	while (mailbox_search_next(search_ctx, &mail)) {
+		if (mail->uid == next_uid) {
+			if (next_uid < uid_filter[i].seq2)
+				next_uid++;
+			else if (++i < count)
+				next_uid = uid_filter[i].seq1;
+			else
+				break;
+		} else {
+			/* next_uid .. mail->uid-1 are expunged */
+			i_assert(mail->uid > next_uid);
+			while (mail->uid > uid_filter[i].seq2) {
+				seq_range_array_add_range(expunged_uids,
+							  next_uid,
+							  uid_filter[i].seq2);
+				i++;
+				i_assert(i < count);
+				next_uid = uid_filter[i].seq1;
+			}
+			if (next_uid != mail->uid) {
+				seq_range_array_add_range(expunged_uids,
+							  next_uid,
+							  mail->uid - 1);
+			}
+			if (uid_filter[i].seq2 != mail->uid)
+				next_uid = mail->uid + 1;
+			else if (++i < count)
+				next_uid = uid_filter[i].seq1;
+			else
+				break;
+		}
+	}
+	if (i < count) {
+		i_assert(next_uid <= uid_filter[i].seq2);
+		seq_range_array_add_range(expunged_uids, next_uid,
+					  uid_filter[i].seq2);
+		i++;
+	}
+	for (; i < count; i++) {
+		seq_range_array_add_range(expunged_uids, uid_filter[i].seq1,
+					  uid_filter[i].seq2);
+	}
+
+	mailbox_get_open_status(box, STATUS_UIDNEXT, &status);
+	seq_range_array_remove_range(expunged_uids, status.uidnext,
+				     (uint32_t)-1);
+
+	if (mailbox_search_deinit(&search_ctx) < 0)
+		ret = -1;
+
+	if (ret == 0 && qresync_args->qresync_sample_seqset != NULL &&
+	    array_is_created(qresync_args->qresync_sample_seqset))
+		expunges_drop_known(box, qresync_args, trans, expunged_uids);
+
+	(void)mailbox_transaction_commit(&trans);
+	return ret;
+}
+
+int imap_fetch_send_vanished(struct client *client, struct mailbox *box,
+			     const struct mail_search_args *search_args,
+			     const struct imap_fetch_qresync_args *qresync_args)
+{
+	const struct mail_search_arg *uidarg = search_args->args;
+	const struct mail_search_arg *modseqarg = uidarg->next;
+	const ARRAY_TYPE(seq_range) *uid_filter;
+	uint64_t modseq;
+	ARRAY_TYPE(seq_range) expunged_uids_range;
+	string_t *str;
+	int ret = 0;
+
+	i_assert(uidarg->type == SEARCH_UIDSET);
+	i_assert(modseqarg->type == SEARCH_MODSEQ);
+
+	uid_filter = &uidarg->value.seqset;
+	modseq = modseqarg->value.modseq->modseq - 1;
+
+	i_array_init(&expunged_uids_range, array_count(uid_filter));
+	if (!mailbox_get_expunged_uids(box, modseq, uid_filter, &expunged_uids_range)) {
+		/* return all expunged UIDs */
+		if (get_expunges_fallback(box, qresync_args, uid_filter,
+					  &expunged_uids_range) < 0) {
+			array_clear(&expunged_uids_range);
+			ret = -1;
+		}
+	}
+	if (array_count(&expunged_uids_range) > 0) {
+		str = str_new(default_pool, 128);
+		str_append(str, "* VANISHED (EARLIER) ");
+		imap_write_seq_range(str, &expunged_uids_range);
+		str_append(str, "\r\n");
+		o_stream_nsend(client->output, str_data(str), str_len(str));
+		str_free(&str);
+	}
+	array_free(&expunged_uids_range);
+	return ret;
+}
+
+static void imap_fetch_init(struct imap_fetch_context *ctx)
+{
+	if (ctx->initialized)
+		return;
+	ctx->initialized = TRUE;
+
+	if (ctx->flags_update_seen && !ctx->flags_have_handler) {
+		ctx->flags_show_only_seen_changes = TRUE;
+		imap_fetch_init_nofail_handler(ctx, imap_fetch_flags_init);
+	}
+	if ((ctx->fetch_data &
+	     (MAIL_FETCH_STREAM_HEADER | MAIL_FETCH_STREAM_BODY)) != 0)
+		ctx->fetch_data |= MAIL_FETCH_NUL_STATE;
+}
+
+void imap_fetch_begin(struct imap_fetch_context *ctx, struct mailbox *box,
+		      struct mail_search_args *search_args)
+{
+	enum mailbox_transaction_flags trans_flags =
+		MAILBOX_TRANSACTION_FLAG_REFRESH;
+	struct mailbox_header_lookup_ctx *wanted_headers = NULL;
+	const char *const *headers;
+
+	i_assert(!ctx->state.fetching);
+
+        imap_fetch_init(ctx);
+        i_zero(&ctx->state);
+
+	if (array_count(&ctx->all_headers) > 0 &&
+	    ((ctx->fetch_data & (MAIL_FETCH_STREAM_HEADER |
+				 MAIL_FETCH_STREAM_BODY)) == 0)) {
+		array_append_zero(&ctx->all_headers);
+
+		headers = array_front(&ctx->all_headers);
+		wanted_headers = mailbox_header_lookup_init(box, headers);
+		array_pop_back(&ctx->all_headers);
+	}
+
+	if (ctx->flags_update_seen) {
+		/* Hide the implicit \Seen flag addition. Otherwise a separate
+		   untagged FETCH FLAGS (\Seen) would be sent on top of the
+		   one FLAGS (\Seen) already added in the main FETCH reply.
+
+		   We don't set this always, because some plugins might want
+		   to do their own flag changes which we don't want hidden.
+		   (Of course this isn't perfect since if implicit \Seen flags
+		   are added, other flag changes are also hidden.) */
+		trans_flags |= MAILBOX_TRANSACTION_FLAG_HIDE;
+	}
+	ctx->state.trans = mailbox_transaction_begin(box, trans_flags,
+						     ctx->reason);
+
+	mail_search_args_init(search_args, box, TRUE,
+			      &ctx->client->search_saved_uidset);
+	ctx->state.search_ctx =
+		mailbox_search_init(ctx->state.trans, search_args, NULL,
+				    ctx->fetch_data, wanted_headers);
+	ctx->state.cur_str = str_new(default_pool, 8192);
+	ctx->state.fetching = TRUE;
+
+	mailbox_header_lookup_unref(&wanted_headers);
+}
+
+static int imap_fetch_flush_buffer(struct imap_fetch_context *ctx)
+{
+	const unsigned char *data;
+	size_t len;
+
+	data = str_data(ctx->state.cur_str);
+	len = str_len(ctx->state.cur_str);
+
+	if (len == 0)
+		return 0;
+
+	/* there's an extra space at the end if we added any fetch items
+	   to buffer */
+	if (data[len-1] == ' ') {
+		len--;
+		ctx->state.cur_first = FALSE;
+	}
+	ctx->state.line_partial = TRUE;
+
+	if (o_stream_send(ctx->client->output, data, len) < 0)
+		return -1;
+
+	str_truncate(ctx->state.cur_str, 0);
+	return 0;
+}
+
+static int imap_fetch_send_nil_reply(struct imap_fetch_context *ctx)
+{
+	const struct imap_fetch_context_handler *handler;
+
+	if (!ctx->state.cur_first)
+		str_append_c(ctx->state.cur_str, ' ');
+
+	handler = array_idx(&ctx->handlers, ctx->state.cur_handler);
+	str_printfa(ctx->state.cur_str, "%s %s ",
+		    handler->name, handler->nil_reply);
+
+	if (!handler->buffered) {
+		if (imap_fetch_flush_buffer(ctx) < 0)
+			return -1;
+	}
+	return 0;
+}
+
+static void imap_fetch_fix_empty_reply(struct imap_fetch_context *ctx)
+{
+	if (ctx->state.line_partial && ctx->state.cur_first) {
+		/* we've flushed an empty "FETCH (" reply so
+		   far. we can't take it back, but RFC 3501
+		   doesn't allow returning empty "FETCH ()"
+		   either, so just add the current message's
+		   UID there. */
+		str_printfa(ctx->state.cur_str, "UID %u ",
+			    ctx->state.cur_mail->uid);
+	}
+}
+
+static bool imap_fetch_cur_failed(struct imap_fetch_context *ctx)
+{
+	ctx->failures = TRUE;
+	if (ctx->client->set->parsed_fetch_failure ==
+	    IMAP_CLIENT_FETCH_FAILURE_DISCONNECT_IMMEDIATELY)
+		return FALSE;
+
+	if (!array_is_created(&ctx->fetch_failed_uids))
+		p_array_init(&ctx->fetch_failed_uids, ctx->ctx_pool, 8);
+	seq_range_array_add(&ctx->fetch_failed_uids, ctx->state.cur_mail->uid);
+
+	if (ctx->error == MAIL_ERROR_NONE) {
+		/* preserve the first error, since it may change in storage. */
+		ctx->errstr = p_strdup(ctx->ctx_pool,
+			mailbox_get_last_error(ctx->state.cur_mail->box, &ctx->error));
+	}
+	return TRUE;
+}
+
+static int imap_fetch_more_int(struct imap_fetch_context *ctx, bool cancel)
+{
+	struct imap_fetch_state *state = &ctx->state;
+	struct client *client = ctx->client;
+	const struct imap_fetch_context_handler *handlers;
+	unsigned int count;
+	int ret;
+
+	if (state->cont_handler != NULL) {
+		ret = state->cont_handler(ctx);
+		if (ret == 0)
+			return 0;
+
+		if (ret < 0) {
+			if (client->output->closed)
+				return -1;
+
+			if (state->cur_mail->expunged) {
+				/* not an error, just lost it. */
+				state->skipped_expunged_msgs = TRUE;
+				if (imap_fetch_send_nil_reply(ctx) < 0)
+					return -1;
+			} else {
+				if (!imap_fetch_cur_failed(ctx))
+					return -1;
+			}
+		}
+
+		state->cont_handler = NULL;
+                state->cur_handler++;
+		if (state->cur_input != NULL)
+			i_stream_unref(&state->cur_input);
+	}
+
+	handlers = array_get(&ctx->handlers, &count);
+	for (;;) {
+		if (o_stream_get_buffer_used_size(client->output) >=
+		    CLIENT_OUTPUT_OPTIMAL_SIZE) {
+			ret = o_stream_flush(client->output);
+			if (ret <= 0)
+				return ret;
+		}
+
+		if (state->cur_mail == NULL) {
+			if (cancel)
+				return 1;
+
+			if (!mailbox_search_next(state->search_ctx,
+						 &state->cur_mail))
+				break;
+
+			str_printfa(state->cur_str, "* %u FETCH (",
+				    state->cur_mail->seq);
+			ctx->fetched_mails_count++;
+			state->cur_first = TRUE;
+			state->cur_str_prefix_size = str_len(state->cur_str);
+			i_assert(!state->line_partial);
+		}
+
+		for (; state->cur_handler < count; state->cur_handler++) {
+			if (str_len(state->cur_str) > 0 &&
+			    !handlers[state->cur_handler].buffered) {
+				/* first non-buffered handler.
+				   flush the buffer. */
+				if (imap_fetch_flush_buffer(ctx) < 0)
+					return -1;
+			}
+
+			i_assert(state->cur_input == NULL);
+			T_BEGIN {
+				const struct imap_fetch_context_handler *h =
+					&handlers[state->cur_handler];
+
+				ret = h->handler(ctx, state->cur_mail,
+						 h->context);
+			} T_END;
+
+			if (ret == 0)
+				return 0;
+
+			if (ret < 0) {
+				if (state->cur_mail->expunged) {
+					/* not an error, just lost it. */
+					state->skipped_expunged_msgs = TRUE;
+					if (imap_fetch_send_nil_reply(ctx) < 0)
+						return -1;
+				} else {
+					i_assert(ret < 0 ||
+						 state->cont_handler != NULL);
+					if (!imap_fetch_cur_failed(ctx))
+						return -1;
+				}
+			}
+
+			state->cont_handler = NULL;
+			if (state->cur_input != NULL)
+				i_stream_unref(&state->cur_input);
+		}
+
+		imap_fetch_fix_empty_reply(ctx);
+		if (str_len(state->cur_str) > 0 &&
+		    (state->line_partial ||
+		     str_len(state->cur_str) != state->cur_str_prefix_size)) {
+			/* no non-buffered handlers */
+			if (imap_fetch_flush_buffer(ctx) < 0)
+				return -1;
+		}
+
+		if (state->line_partial)
+			o_stream_nsend(client->output, ")\r\n", 3);
+		client->last_output = ioloop_time;
+
+		state->cur_mail = NULL;
+		state->cur_handler = 0;
+		state->line_partial = FALSE;
+	}
+
+	return ctx->failures ? -1 : 1;
+}
+
+int imap_fetch_more(struct imap_fetch_context *ctx,
+		    struct client_command_context *cmd)
+{
+	int ret;
+
+	i_assert(ctx->client->output_cmd_lock == NULL ||
+		 ctx->client->output_cmd_lock == cmd);
+
+	ret = imap_fetch_more_int(ctx, cmd->cancel);
+	if (ret < 0)
+		ctx->state.failed = TRUE;
+	if (ctx->state.line_partial) {
+		/* nothing can be sent until FETCH is finished */
+		ctx->client->output_cmd_lock = cmd;
+	}
+	if (cmd->cancel && ctx->client->output_cmd_lock != NULL) {
+		/* canceling didn't really work. we must not output
+		   anything anymore. */
+		if (!ctx->client->destroyed)
+			client_disconnect(ctx->client, "Failed to cancel FETCH");
+		ctx->client->output_cmd_lock = NULL;
+	}
+	return ret;
+}
+
+int imap_fetch_more_no_lock_update(struct imap_fetch_context *ctx)
+{
+	int ret;
+
+	ret = imap_fetch_more_int(ctx, FALSE);
+	if (ret < 0) {
+		ctx->state.failed = TRUE;
+		if (ctx->state.line_partial) {
+			/* we can't send any more replies to client, because
+			   the FETCH reply wasn't fully sent. */
+			client_disconnect(ctx->client,
+				"NOTIFY failed in the middle of FETCH reply");
+		}
+	}
+	return ret;
+}
+
+int imap_fetch_end(struct imap_fetch_context *ctx)
+{
+	struct imap_fetch_state *state = &ctx->state;
+
+	if (ctx->state.fetching) {
+		ctx->state.fetching = FALSE;
+		if (state->line_partial) {
+			imap_fetch_fix_empty_reply(ctx);
+			if (imap_fetch_flush_buffer(ctx) < 0)
+				state->failed = TRUE;
+			if (o_stream_send(ctx->client->output, ")\r\n", 3) < 0)
+				state->failed = TRUE;
+		}
+	}
+	ctx->client->output_cmd_lock = NULL;
+
+	str_free(&state->cur_str);
+
+	i_stream_unref(&state->cur_input);
+
+	if (state->search_ctx != NULL) {
+		if (mailbox_search_deinit(&state->search_ctx) < 0)
+			state->failed = TRUE;
+	}
+
+	if (state->trans != NULL) {
+		/* even if something failed, we want to commit changes to
+		   cache, as well as possible \Seen flag changes for FETCH
+		   replies we returned so far. */
+		if (mailbox_transaction_commit(&state->trans) < 0)
+			state->failed = TRUE;
+	}
+	return state->failed ? -1 : 0;
+}
+
+void imap_fetch_free(struct imap_fetch_context **_ctx)
+{
+	struct imap_fetch_context *ctx = *_ctx;
+	const struct imap_fetch_context_handler *handler;
+
+	*_ctx = NULL;
+
+	(void)imap_fetch_end(ctx);
+
+	array_foreach(&ctx->handlers, handler) {
+		if (handler->want_deinit)
+			handler->handler(ctx, NULL, handler->context);
+	}
+	pool_unref(&ctx->ctx_pool);
+}
+
+static int fetch_body(struct imap_fetch_context *ctx, struct mail *mail,
+		      void *context ATTR_UNUSED)
+{
+	const char *body;
+
+	if (mail_get_special(mail, MAIL_FETCH_IMAP_BODY, &body) < 0)
+		return -1;
+
+	if (ctx->state.cur_first)
+		ctx->state.cur_first = FALSE;
+	else {
+		if (o_stream_send(ctx->client->output, " ", 1) < 0)
+			return -1;
+	}
+
+	if (o_stream_send(ctx->client->output, "BODY (", 6) < 0 ||
+	    o_stream_send_str(ctx->client->output, body) < 0 ||
+	    o_stream_send(ctx->client->output, ")", 1) < 0)
+		return -1;
+	return 1;
+}
+
+static bool fetch_body_init(struct imap_fetch_init_context *ctx)
+{
+	if (ctx->name[4] == '\0') {
+		ctx->fetch_ctx->fetch_data |= MAIL_FETCH_IMAP_BODY;
+		imap_fetch_add_handler(ctx, 0, "("BODY_NIL_REPLY")",
+				       fetch_body, NULL);
+		return TRUE;
+	}
+	return imap_fetch_body_section_init(ctx);
+}
+
+static int fetch_bodystructure(struct imap_fetch_context *ctx,
+			       struct mail *mail, void *context ATTR_UNUSED)
+{
+	const char *bodystructure;
+
+	if (mail_get_special(mail, MAIL_FETCH_IMAP_BODYSTRUCTURE,
+			     &bodystructure) < 0)
+		return -1;
+
+	if (ctx->state.cur_first)
+		ctx->state.cur_first = FALSE;
+	else {
+		if (o_stream_send(ctx->client->output, " ", 1) < 0)
+			return -1;
+	}
+
+	if (o_stream_send(ctx->client->output, "BODYSTRUCTURE (", 15) < 0 ||
+	    o_stream_send_str(ctx->client->output, bodystructure) < 0 ||
+	    o_stream_send(ctx->client->output, ")", 1) < 0)
+		return -1;
+
+	return 1;
+}
+
+static bool fetch_bodystructure_init(struct imap_fetch_init_context *ctx)
+{
+	ctx->fetch_ctx->fetch_data |= MAIL_FETCH_IMAP_BODYSTRUCTURE;
+	imap_fetch_add_handler(ctx, 0, "("BODY_NIL_REPLY" NIL NIL NIL NIL)",
+			       fetch_bodystructure, NULL);
+	return TRUE;
+}
+
+static int fetch_envelope(struct imap_fetch_context *ctx, struct mail *mail,
+			  void *context ATTR_UNUSED)
+{
+	const char *envelope;
+
+	if (mail_get_special(mail, MAIL_FETCH_IMAP_ENVELOPE, &envelope) < 0)
+		return -1;
+
+	if (ctx->state.cur_first)
+		ctx->state.cur_first = FALSE;
+	else {
+		if (o_stream_send(ctx->client->output, " ", 1) < 0)
+			return -1;
+	}
+
+	if (o_stream_send(ctx->client->output, "ENVELOPE (", 10) < 0 ||
+	    o_stream_send_str(ctx->client->output, envelope) < 0 ||
+	    o_stream_send(ctx->client->output, ")", 1) < 0)
+		return -1;
+	return 1;
+}
+
+static bool fetch_envelope_init(struct imap_fetch_init_context *ctx)
+{
+	ctx->fetch_ctx->fetch_data |= MAIL_FETCH_IMAP_ENVELOPE;
+	imap_fetch_add_handler(ctx, 0, ENVELOPE_NIL_REPLY,
+			       fetch_envelope, NULL);
+	return TRUE;
+}
+
+static int fetch_flags(struct imap_fetch_context *ctx, struct mail *mail,
+		       void *context ATTR_UNUSED)
+{
+	enum mail_flags flags;
+	const char *const *keywords;
+
+	flags = mail_get_flags(mail);
+	if (ctx->flags_update_seen && (flags & MAIL_SEEN) == 0 &&
+	    !mailbox_is_readonly(mail->box)) {
+		/* Add \Seen flag */
+		ctx->state.seen_flags_changed = TRUE;
+		flags |= MAIL_SEEN;
+		mail_update_flags(mail, MODIFY_ADD, MAIL_SEEN);
+	} else if (ctx->flags_show_only_seen_changes) {
+		return 1;
+	}
+
+	keywords = client_get_keyword_names(ctx->client, &ctx->tmp_keywords,
+			mail_get_keyword_indexes(mail));
+
+	str_append(ctx->state.cur_str, "FLAGS (");
+	imap_write_flags(ctx->state.cur_str, flags, keywords);
+	str_append(ctx->state.cur_str, ") ");
+	return 1;
+}
+
+bool imap_fetch_flags_init(struct imap_fetch_init_context *ctx)
+{
+	ctx->fetch_ctx->flags_have_handler = TRUE;
+	ctx->fetch_ctx->fetch_data |= MAIL_FETCH_FLAGS;
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       "()", fetch_flags, NULL);
+	return TRUE;
+}
+
+static int fetch_internaldate(struct imap_fetch_context *ctx, struct mail *mail,
+			      void *context ATTR_UNUSED)
+{
+	time_t date;
+
+	if (mail_get_received_date(mail, &date) < 0)
+		return -1;
+
+	str_printfa(ctx->state.cur_str, "INTERNALDATE \"%s\" ",
+		    imap_to_datetime(date));
+	return 1;
+}
+
+static bool fetch_internaldate_init(struct imap_fetch_init_context *ctx)
+{
+	ctx->fetch_ctx->fetch_data |= MAIL_FETCH_RECEIVED_DATE;
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       "\"01-Jan-1970 00:00:00 +0000\"",
+			       fetch_internaldate, NULL);
+	return TRUE;
+}
+
+static int fetch_modseq(struct imap_fetch_context *ctx, struct mail *mail,
+			void *context ATTR_UNUSED)
+{
+	uint64_t modseq;
+
+	modseq = mail_get_modseq(mail);
+	if (ctx->client->highest_fetch_modseq < modseq)
+		ctx->client->highest_fetch_modseq = modseq;
+	str_printfa(ctx->state.cur_str, "MODSEQ (%"PRIu64") ", modseq);
+	return 1;
+}
+
+bool imap_fetch_modseq_init(struct imap_fetch_init_context *ctx)
+{
+	if (ctx->fetch_ctx->client->nonpermanent_modseqs) {
+		ctx->error = "FETCH MODSEQ can't be used with non-permanent modseqs";
+		return FALSE;
+	}
+	client_enable(ctx->fetch_ctx->client, imap_feature_condstore);
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       NULL, fetch_modseq, NULL);
+	return TRUE;
+}
+
+static int fetch_uid(struct imap_fetch_context *ctx, struct mail *mail,
+		     void *context ATTR_UNUSED)
+{
+	str_printfa(ctx->state.cur_str, "UID %u ", mail->uid);
+	return 1;
+}
+
+bool imap_fetch_uid_init(struct imap_fetch_init_context *ctx)
+{
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       NULL, fetch_uid, NULL);
+	return TRUE;
+}
+
+static int imap_fetch_savedate(struct imap_fetch_context *ctx, struct mail *mail,
+			       void *context ATTR_UNUSED)
+{
+	time_t date;
+	int ret;
+
+	ret = mail_get_save_date(mail, &date);
+	if (ret < 0)
+		return -1;
+
+	if (ret == 0)
+		str_append(ctx->state.cur_str, "SAVEDATE NIL ");
+	else {
+		str_printfa(ctx->state.cur_str, "SAVEDATE \"%s\" ",
+			    imap_to_datetime(date));
+	}
+	return 1;
+}
+
+static bool imap_fetch_savedate_init(struct imap_fetch_init_context *ctx)
+{
+	ctx->fetch_ctx->fetch_data |= MAIL_FETCH_SAVE_DATE;
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       "NIL", imap_fetch_savedate, NULL);
+	return TRUE;
+}
+
+static int fetch_guid(struct imap_fetch_context *ctx, struct mail *mail,
+		      void *context ATTR_UNUSED)
+{
+	const char *value;
+
+	if (mail_get_special(mail, MAIL_FETCH_GUID, &value) < 0)
+		return -1;
+
+	str_append(ctx->state.cur_str, "X-GUID ");
+	imap_append_astring(ctx->state.cur_str, value);
+	str_append_c(ctx->state.cur_str, ' ');
+	return 1;
+}
+
+static bool fetch_guid_init(struct imap_fetch_init_context *ctx)
+{
+	ctx->fetch_ctx->fetch_data |= MAIL_FETCH_GUID;
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       "", fetch_guid, NULL);
+	return TRUE;
+}
+
+static int fetch_x_mailbox(struct imap_fetch_context *ctx, struct mail *mail,
+			   void *context ATTR_UNUSED)
+{
+	const char *name;
+	string_t *mutf7_name;
+
+	if (mail_get_special(mail, MAIL_FETCH_MAILBOX_NAME, &name) < 0) {
+		/* This can happen with virtual mailbox if the backend mail
+		   is expunged. */
+		return -1;
+	}
+
+	mutf7_name = t_str_new(strlen(name)*2);
+	if (imap_utf8_to_utf7(name, mutf7_name) < 0)
+		i_panic("FETCH: Mailbox name not UTF-8: %s", name);
+
+	str_append(ctx->state.cur_str, "X-MAILBOX ");
+	imap_append_astring(ctx->state.cur_str, str_c(mutf7_name));
+	str_append_c(ctx->state.cur_str, ' ');
+	return 1;
+}
+
+static bool fetch_x_mailbox_init(struct imap_fetch_init_context *ctx)
+{
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       NULL, fetch_x_mailbox, NULL);
+	return TRUE;
+}
+
+static int fetch_x_real_uid(struct imap_fetch_context *ctx, struct mail *mail,
+			    void *context ATTR_UNUSED)
+{
+	struct mail *real_mail;
+
+	if (mail_get_backend_mail(mail, &real_mail) < 0)
+		return -1;
+	str_printfa(ctx->state.cur_str, "X-REAL-UID %u ", real_mail->uid);
+	return 1;
+}
+
+static bool fetch_x_real_uid_init(struct imap_fetch_init_context *ctx)
+{
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       NULL, fetch_x_real_uid, NULL);
+	return TRUE;
+}
+
+static int fetch_x_savedate(struct imap_fetch_context *ctx, struct mail *mail,
+			    void *context ATTR_UNUSED)
+{
+	time_t date;
+
+	if (mail_get_save_date(mail, &date) < 0)
+		return -1;
+
+	str_printfa(ctx->state.cur_str, "X-SAVEDATE \"%s\" ",
+		    imap_to_datetime(date));
+	return 1;
+}
+
+static bool fetch_x_savedate_init(struct imap_fetch_init_context *ctx)
+{
+	ctx->fetch_ctx->fetch_data |= MAIL_FETCH_SAVE_DATE;
+	imap_fetch_add_handler(ctx, IMAP_FETCH_HANDLER_FLAG_BUFFERED,
+			       "\"01-Jan-1970 00:00:00 +0000\"",
+			       fetch_x_savedate, NULL);
+	return TRUE;
+}
+
+static const struct imap_fetch_handler
+imap_fetch_default_handlers[] = {
+	{ "BINARY", imap_fetch_binary_init },
+	{ "BODY", fetch_body_init },
+	{ "BODYSTRUCTURE", fetch_bodystructure_init },
+	{ "ENVELOPE", fetch_envelope_init },
+	{ "FLAGS", imap_fetch_flags_init },
+	{ "INTERNALDATE", fetch_internaldate_init },
+	{ "MODSEQ", imap_fetch_modseq_init },
+	{ "PREVIEW", imap_fetch_preview_init },
+	{ "RFC822", imap_fetch_rfc822_init },
+	{ "SNIPPET", imap_fetch_snippet_init },
+	{ "UID", imap_fetch_uid_init },
+	{ "SAVEDATE", imap_fetch_savedate_init },
+	{ "X-GUID", fetch_guid_init },
+	{ "X-MAILBOX", fetch_x_mailbox_init },
+	{ "X-REAL-UID", fetch_x_real_uid_init },
+	{ "X-SAVEDATE", fetch_x_savedate_init }
+};
+
+void imap_fetch_handlers_init(void)
+{
+	i_array_init(&fetch_handlers, 32);
+	imap_fetch_handlers_register(imap_fetch_default_handlers,
+				     N_ELEMENTS(imap_fetch_default_handlers));
+}
+
+void imap_fetch_handlers_deinit(void)
+{
+	array_free(&fetch_handlers);
+}
diff --git a/src/imap/imap-fetch.h b/src/imap/imap-fetch.h
new file mode 100644
index 0000000..ba8cfc8
--- /dev/null
+++ b/src/imap/imap-fetch.h
@@ -0,0 +1,166 @@
+#ifndef IMAP_FETCH_H
+#define IMAP_FETCH_H
+
+struct imap_fetch_context;
+
+enum imap_fetch_handler_flags {
+	IMAP_FETCH_HANDLER_FLAG_BUFFERED	= 0x01,
+	IMAP_FETCH_HANDLER_FLAG_WANT_DEINIT	= 0x02
+};
+
+/* Returns 1 = ok, 0 = client output buffer full, call again, -1 = error.
+   mail = NULL for deinit. */
+typedef int imap_fetch_handler_t(struct imap_fetch_context *ctx,
+				 struct mail *mail, void *context);
+
+struct imap_fetch_init_context {
+	struct imap_fetch_context *fetch_ctx;
+	pool_t pool;
+
+	const char *name;
+	const struct imap_arg *args;
+
+	const char *error;
+};
+
+struct imap_fetch_handler {
+	const char *name;
+
+	/* Returns FALSE and sets ctx->error if arg is invalid */
+	bool (*init)(struct imap_fetch_init_context *ctx);
+};
+
+struct imap_fetch_context_handler {
+	imap_fetch_handler_t *handler;
+	void *context;
+
+	const char *name;
+	const char *nil_reply;
+
+	bool buffered:1;
+	bool want_deinit:1;
+};
+
+struct imap_fetch_qresync_args {
+	const ARRAY_TYPE(uint32_t) *qresync_sample_seqset;
+	const ARRAY_TYPE(uint32_t) *qresync_sample_uidset;
+};
+
+struct imap_fetch_state {
+	struct mailbox_transaction_context *trans;
+	struct mail_search_context *search_ctx;
+
+	struct mail *cur_mail;
+	unsigned int cur_handler;
+	const char *cur_human_name;
+	uoff_t cur_size;
+	enum mail_fetch_field cur_size_field;
+	string_t *cur_str;
+	size_t cur_str_prefix_size;
+	struct istream *cur_input;
+	bool skip_cr;
+	int (*cont_handler)(struct imap_fetch_context *ctx);
+	uint64_t *cur_stats_sizep;
+
+	bool fetching:1;
+	bool seen_flags_changed:1;
+	/* TRUE if the first FETCH parameter result hasn't yet been sent to
+	   the IMAP client. Note that this doesn't affect buffered content in
+	   cur_str until it gets flushed out. */
+	bool cur_first:1;
+	/* TRUE if the cur_str prefix has been flushed. More data may still
+	   be added to it. */
+	bool line_partial:1;
+	bool skipped_expunged_msgs:1;
+	bool failed:1;
+};
+
+struct imap_fetch_context {
+	struct client *client;
+	pool_t ctx_pool;
+	const char *reason;
+
+	enum mail_fetch_field fetch_data;
+	ARRAY_TYPE(const_string) all_headers;
+
+	ARRAY(struct imap_fetch_context_handler) handlers;
+	unsigned int buffered_handlers_count;
+
+	ARRAY_TYPE(keywords) tmp_keywords;
+
+	struct imap_fetch_state state;
+	ARRAY_TYPE(seq_range) fetch_failed_uids;
+	unsigned int fetched_mails_count;
+
+	enum mail_error error;
+	const char *errstr;
+
+	bool initialized:1;
+	bool failures:1;
+	bool flags_have_handler:1;
+	bool flags_update_seen:1;
+	bool flags_show_only_seen_changes:1;
+	/* HEADER.FIELDS or HEADER.FIELDS.NOT is fetched */
+	bool fetch_header_fields:1;
+};
+
+void imap_fetch_handlers_register(const struct imap_fetch_handler *handlers,
+				  size_t count);
+void imap_fetch_handler_unregister(const char *name);
+
+void imap_fetch_add_handler(struct imap_fetch_init_context *ctx,
+			    enum imap_fetch_handler_flags flags,
+			    const char *nil_reply,
+			    imap_fetch_handler_t *handler, void *context)
+	ATTR_NULL(3, 5);
+#define imap_fetch_add_handler(ctx, flags, nil_reply, handler, context) \
+	  imap_fetch_add_handler(ctx, flags, nil_reply - \
+		CALLBACK_TYPECHECK(handler, int (*)( \
+			struct imap_fetch_context *, struct mail *, \
+			typeof(context))), \
+		(imap_fetch_handler_t *)handler, context)
+
+int imap_fetch_att_list_parse(struct client *client, pool_t pool,
+			      const struct imap_arg *list,
+			      struct imap_fetch_context **fetch_ctx_r,
+			      const char **client_error_r);
+
+struct imap_fetch_context *
+imap_fetch_alloc(struct client *client, pool_t pool, const char *reason);
+void imap_fetch_free(struct imap_fetch_context **ctx);
+bool imap_fetch_init_handler(struct imap_fetch_init_context *init_ctx);
+void imap_fetch_init_nofail_handler(struct imap_fetch_context *ctx,
+				    bool (*init)(struct imap_fetch_init_context *));
+const struct imap_fetch_handler *imap_fetch_handler_lookup(const char *name);
+
+void imap_fetch_begin(struct imap_fetch_context *ctx, struct mailbox *box,
+		      struct mail_search_args *search_args);
+int imap_fetch_send_vanished(struct client *client, struct mailbox *box,
+			     const struct mail_search_args *search_args,
+			     const struct imap_fetch_qresync_args *qresync_args);
+/* Returns 1 if finished, 0 if more data is needed, -1 if error.
+   When 0 is returned, line_partial=TRUE if literal is open and must be
+   finished before anything else to client. */
+int imap_fetch_more(struct imap_fetch_context *ctx,
+		    struct client_command_context *cmd);
+/* Like imap_fetch_more(), but don't check/update output_lock.
+   The caller must handle this itself. */
+int imap_fetch_more_no_lock_update(struct imap_fetch_context *ctx);
+int imap_fetch_end(struct imap_fetch_context *ctx);
+int imap_fetch_more(struct imap_fetch_context *ctx,
+		    struct client_command_context *cmd);
+
+bool imap_fetch_flags_init(struct imap_fetch_init_context *ctx);
+bool imap_fetch_modseq_init(struct imap_fetch_init_context *ctx);
+bool imap_fetch_uid_init(struct imap_fetch_init_context *ctx);
+
+bool imap_fetch_body_section_init(struct imap_fetch_init_context *ctx);
+bool imap_fetch_rfc822_init(struct imap_fetch_init_context *ctx);
+bool imap_fetch_binary_init(struct imap_fetch_init_context *ctx);
+bool imap_fetch_preview_init(struct imap_fetch_init_context *ctx);
+bool imap_fetch_snippet_init(struct imap_fetch_init_context *ctx);
+
+void imap_fetch_handlers_init(void);
+void imap_fetch_handlers_deinit(void);
+
+#endif
diff --git a/src/imap/imap-list.c b/src/imap/imap-list.c
new file mode 100644
index 0000000..38a81ba
--- /dev/null
+++ b/src/imap/imap-list.c
@@ -0,0 +1,35 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "imap-list.h"
+
+bool imap_mailbox_flags2str(string_t *str, enum mailbox_info_flags flags)
+{
+	size_t orig_len = str_len(str);
+
+	if ((flags & MAILBOX_SUBSCRIBED) != 0)
+		str_append(str, "\\Subscribed ");
+
+	if ((flags & MAILBOX_NOSELECT) != 0)
+		str_append(str, "\\Noselect ");
+	if ((flags & MAILBOX_NONEXISTENT) != 0)
+		str_append(str, "\\NonExistent ");
+
+	if ((flags & MAILBOX_CHILDREN) != 0)
+		str_append(str, "\\HasChildren ");
+	else if ((flags & MAILBOX_NOINFERIORS) != 0)
+		str_append(str, "\\NoInferiors ");
+	else if ((flags & MAILBOX_NOCHILDREN) != 0)
+		str_append(str, "\\HasNoChildren ");
+
+	if ((flags & MAILBOX_MARKED) != 0)
+		str_append(str, "\\Marked ");
+	if ((flags & MAILBOX_UNMARKED) != 0)
+		str_append(str, "\\UnMarked ");
+
+	if (str_len(str) == orig_len)
+		return FALSE;
+	str_truncate(str, str_len(str)-1);
+	return TRUE;
+}
diff --git a/src/imap/imap-list.h b/src/imap/imap-list.h
new file mode 100644
index 0000000..6a0e076
--- /dev/null
+++ b/src/imap/imap-list.h
@@ -0,0 +1,7 @@
+#ifndef IMAP_LIST_H
+#define IMAP_LIST_H
+
+/* Returns TRUE if anything was added to the string. */
+bool imap_mailbox_flags2str(string_t *str, enum mailbox_info_flags flags);
+
+#endif
diff --git a/src/imap/imap-master-client.c b/src/imap/imap-master-client.c
new file mode 100644
index 0000000..66f7f3d
--- /dev/null
+++ b/src/imap/imap-master-client.c
@@ -0,0 +1,415 @@
+/* Copyright (c) 2014-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "connection.h"
+#include "istream.h"
+#include "istream-unix.h"
+#include "ostream.h"
+#include "base64.h"
+#include "str.h"
+#include "strescape.h"
+#include "str-sanitize.h"
+#include "time-util.h"
+#include "master-service.h"
+#include "mail-storage-service.h"
+#include "imap-client.h"
+#include "imap-state.h"
+#include "imap-master-client.h"
+
+struct imap_master_client {
+	struct connection conn;
+	bool imap_client_created;
+};
+
+struct imap_master_input {
+	/* input we've already read from the IMAP client. */
+	buffer_t *client_input;
+	/* output that imap-hibernate was supposed to send to IMAP client,
+	   but couldn't send it yet. */
+	buffer_t *client_output;
+	/* IMAP connection state */
+	buffer_t *state;
+	/* command tag */
+	const char *tag;
+	/* Timestamp when hibernation started */
+	struct timeval hibernation_start_time;
+
+	dev_t peer_dev;
+	ino_t peer_ino;
+
+	bool state_import_bad_idle_done;
+	bool state_import_idle_continue;
+};
+
+static struct connection_list *master_clients = NULL;
+
+static void imap_master_client_destroy(struct connection *conn)
+{
+	struct imap_master_client *client = (struct imap_master_client *)conn;
+
+	if (!client->imap_client_created)
+		master_service_client_connection_destroyed(master_service);
+	connection_deinit(conn);
+	i_free(conn);
+}
+
+static int
+imap_master_client_parse_input(const char *const *args, pool_t pool,
+			       struct mail_storage_service_input *input_r,
+			       struct imap_master_input *master_input_r,
+			       const char **error_r)
+{
+	const char *key, *value;
+	unsigned int peer_dev_major = 0, peer_dev_minor = 0;
+
+	i_zero(input_r);
+	i_zero(master_input_r);
+	master_input_r->client_input = buffer_create_dynamic(pool, 64);
+	master_input_r->client_output = buffer_create_dynamic(pool, 16);
+	master_input_r->state = buffer_create_dynamic(pool, 512);
+
+	input_r->module = input_r->service = "imap";
+	/* we never want to do userdb lookup again when restoring the client.
+	   we have the userdb_fields cached already. */
+	input_r->flags_override_remove = MAIL_STORAGE_SERVICE_FLAG_USERDB_LOOKUP;
+
+	if (args[0] == NULL) {
+		*error_r = "Missing username in input";
+		return -1;
+	}
+	input_r->username = args[0];
+
+	for (args++; *args != NULL; args++) {
+		value = strchr(*args, '=');
+		if (value != NULL)
+			key = t_strdup_until(*args, value++);
+		else {
+			key = *args;
+			value = "";
+		}
+		if (strcmp(key, "lip") == 0) {
+			if (net_addr2ip(value, &input_r->local_ip) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid lip value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "lport") == 0) {
+			if (net_str2port(value, &input_r->local_port) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid lport value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "rip") == 0) {
+			if (net_addr2ip(value, &input_r->remote_ip) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid rip value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "rport") == 0) {
+			if (net_str2port(value, &input_r->remote_port) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid rport value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "peer_dev_major") == 0) {
+			if (str_to_uint(value, &peer_dev_major) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid peer_dev_major value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "peer_dev_minor") == 0) {
+			if (str_to_uint(value, &peer_dev_minor) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid peer_dev_minor value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "peer_ino") == 0) {
+			if (str_to_ino(value, &master_input_r->peer_ino) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid peer_ino value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "session") == 0) {
+			input_r->session_id = value;
+		} else if (strcmp(key, "session_created") == 0) {
+			if (str_to_time(value, &input_r->session_create_time) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid session_created value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "hibernation_started") == 0) {
+			if (str_to_timeval(value, &master_input_r->hibernation_start_time) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid hibernation_started value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "userdb_fields") == 0) {
+			input_r->userdb_fields =
+				t_strsplit_tabescaped(value);
+		} else if (strcmp(key, "client_input") == 0) {
+			if (base64_decode(value, strlen(value), NULL,
+					  master_input_r->client_input) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid client_input base64 value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "client_output") == 0) {
+			if (base64_decode(value, strlen(value), NULL,
+					  master_input_r->client_output) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid client_output base64 value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "state") == 0) {
+			if (base64_decode(value, strlen(value), NULL,
+					  master_input_r->state) < 0) {
+				*error_r = t_strdup_printf(
+					"Invalid state base64 value: %s", value);
+				return -1;
+			}
+		} else if (strcmp(key, "tag") == 0) {
+			master_input_r->tag = t_strdup(value);
+		} else if (strcmp(key, "bad-done") == 0) {
+			master_input_r->state_import_bad_idle_done = TRUE;
+		} else if (strcmp(key, "idle-continue") == 0) {
+			master_input_r->state_import_idle_continue = TRUE;
+		}
+	}
+	if (peer_dev_major != 0 || peer_dev_minor != 0) {
+		master_input_r->peer_dev =
+			makedev(peer_dev_major, peer_dev_minor);
+	}
+	return 0;
+}
+
+static int imap_master_client_verify(const struct imap_master_input *master_input,
+				     int fd_client, const char **error_r)
+{
+	struct stat peer_st;
+
+	if (master_input->peer_ino == 0)
+		return 0;
+
+	/* make sure we have the right fd */
+	if (fstat(fd_client, &peer_st) < 0) {
+		*error_r = t_strdup_printf("fstat(peer) failed: %m");
+		return -1;
+	}
+	if (peer_st.st_ino != master_input->peer_ino ||
+	    !CMP_DEV_T(peer_st.st_dev, master_input->peer_dev)) {
+		*error_r = t_strdup_printf(
+			"BUG: Expected peer device=%lu,%lu inode=%s doesn't match "
+			"client fd's actual device=%lu,%lu inode=%s",
+			(unsigned long)major(peer_st.st_dev),
+			(unsigned long)minor(peer_st.st_dev), dec2str(peer_st.st_ino),
+			(unsigned long)major(master_input->peer_dev),
+			(unsigned long)minor(master_input->peer_dev),
+			dec2str(master_input->peer_ino));
+		return -1;
+	}
+	return 0;
+}
+
+static int
+imap_master_client_input_args(struct connection *conn, const char *const *args,
+			      int fd_client, pool_t pool)
+{
+	struct imap_master_client *client = (struct imap_master_client *)conn;
+	struct client *imap_client;
+	struct mail_storage_service_input input;
+	struct imap_master_input master_input;
+	const char *error = NULL, *reason;
+	int ret;
+
+	if (imap_master_client_parse_input(args, pool, &input, &master_input,
+					   &error) < 0) {
+		e_error(conn->event, "imap-master: Failed to parse client input: %s", error);
+		o_stream_nsend_str(conn->output, t_strdup_printf(
+			"-Failed to parse client input: %s\n", error));
+		i_close_fd(&fd_client);
+		return -1;
+	}
+	if (imap_master_client_verify(&master_input, fd_client, &error) < 0) {
+		e_error(conn->event, "imap-master: Failed to verify client input: %s", error);
+		o_stream_nsend_str(conn->output, t_strdup_printf(
+			"-Failed to verify client input: %s\n", error));
+		i_close_fd(&fd_client);
+		return -1;
+	}
+
+	/* NOTE: before client_create_from_input() on failures we need to close
+	   fd_client, but afterward it gets closed by client_destroy() */
+	ret = client_create_from_input(&input, fd_client, fd_client,
+				       &imap_client, &error);
+	if (ret < 0) {
+		e_error(conn->event,
+			"imap-master(%s): Failed to create client: %s",
+			input.username, error);
+		o_stream_nsend_str(conn->output, t_strdup_printf(
+			"-Failed to create client: %s\n", error));
+		i_close_fd(&fd_client);
+		return -1;
+	}
+	client->imap_client_created = TRUE;
+
+	long long hibernation_usecs =
+		timeval_diff_usecs(&ioloop_timeval,
+				   &master_input.hibernation_start_time);
+	struct event *event = event_create(imap_client->event);
+	event_set_name(event, "imap_client_unhibernated");
+	event_add_int(event, "hibernation_usecs", hibernation_usecs);
+	imap_client->state_import_bad_idle_done =
+		master_input.state_import_bad_idle_done;
+	imap_client->state_import_idle_continue =
+		master_input.state_import_idle_continue;
+	if (imap_client->state_import_bad_idle_done) {
+		reason = "IDLE was stopped with BAD command";
+		event_add_str(event, "reason", "idle_bad_reply");
+	} else if (imap_client->state_import_idle_continue) {
+		reason = "mailbox changes need to be sent";
+		event_add_str(event, "reason", "mailbox_changes");
+	} else {
+		reason = "IDLE was stopped with DONE";
+		event_add_str(event, "reason", "idle_done");
+	}
+
+	/* Send a success notification before we start anything that lasts
+	   potentially a long time. imap-hibernate process is waiting for us
+	   to answer. Even if we fail later, we log the error anyway. From now
+	   on it's our responsibility to also log the imap_client_unhibernated
+	   event. */
+	o_stream_nsend_str(conn->output, "+\n");
+	(void)o_stream_flush(conn->output);
+
+	if (master_input.client_input->used > 0) {
+		client_add_istream_prefix(imap_client,
+					  master_input.client_input->data,
+					  master_input.client_input->used);
+	}
+
+	client_create_finish_io(imap_client);
+	if (client_create_finish(imap_client, &error) < 0) {
+		event_add_str(event, "error", error);
+		e_error(event, "imap-master: %s", error);
+		event_unref(&event);
+		client_destroy(imap_client, error);
+		return -1;
+	}
+	/* log prefix is set at this point, so we don't need to add the
+	   username anymore to the log messages */
+
+	o_stream_nsend(imap_client->output,
+		       master_input.client_output->data,
+		       master_input.client_output->used);
+
+	struct event_reason *event_reason =
+		event_reason_begin("imap:unhibernate");
+	ret = imap_state_import_internal(imap_client, master_input.state->data,
+					 master_input.state->used, &error);
+	event_reason_end(&event_reason);
+
+	if (ret <= 0) {
+		error = t_strdup_printf("Failed to import client state: %s", error);
+		event_add_str(event, "error", error);
+		e_error(event, "imap-master: %s", error);
+		event_unref(&event);
+		client_destroy(imap_client, "Client state initialization failed");
+		return -1;
+	}
+	if (imap_client->mailbox != NULL) {
+		/* Would be nice to set this earlier, but the previous errors
+		   happen rarely enough that it shouldn't really matter. */
+		event_add_str(event, "mailbox",
+			      mailbox_get_vname(imap_client->mailbox));
+	}
+
+	if (master_input.tag != NULL)
+		imap_state_import_idle_cmd_tag(imap_client, master_input.tag);
+
+	e_debug(event, "imap-master: Unhibernated because %s "
+		"(hibernated for %llu.%06llu secs)", reason,
+		hibernation_usecs/1000000, hibernation_usecs%1000000);
+	event_unref(&event);
+
+	/* make sure all pending input gets handled */
+	if (master_input.client_input->used > 0) {
+		e_debug(imap_client->event,
+			"imap-master: Pending client input: '%s'",
+			str_sanitize(str_c(master_input.client_input), 128));
+		io_set_pending(imap_client->io);
+	}
+
+	imap_refresh_proctitle();
+	/* we'll always disconnect the client afterwards */
+	return -1;
+}
+
+static int
+imap_master_client_input_line(struct connection *conn, const char *line)
+{
+	char *const *args;
+	pool_t pool;
+	int fd_client, ret;
+
+	if (!conn->version_received) {
+		if (connection_handshake_args_default(conn, t_strsplit_tabescaped(line)) < 0)
+			return -1;
+		conn->version_received = TRUE;
+		return 1;
+	}
+
+	fd_client = i_stream_unix_get_read_fd(conn->input);
+	if (fd_client == -1) {
+		e_error(conn->event, "imap-master: IMAP client fd not received");
+		return -1;
+	}
+
+	if (imap_debug)
+		e_debug(conn->event, "imap-master: Client input: %s", line);
+
+	pool = pool_alloconly_create("imap master client cmd", 1024);
+	args = p_strsplit_tabescaped(pool, line);
+	ret = imap_master_client_input_args(conn, (const void *)args,
+					    fd_client, pool);
+	pool_unref(&pool);
+	return ret;
+}
+
+void imap_master_client_create(int fd)
+{
+	struct imap_master_client *client;
+
+	client = i_new(struct imap_master_client, 1);
+	client->conn.unix_socket = TRUE;
+	connection_init_server(master_clients, &client->conn,
+			       "imap-master", fd, fd);
+
+	/* read the first file descriptor that we can */
+	i_stream_unix_set_read_fd(client->conn.input);
+}
+
+static struct connection_settings client_set = {
+	.service_name_in = "imap-master",
+	.service_name_out = "imap-master",
+	.major_version = 1,
+	.minor_version = 0,
+
+	.input_max_size = SIZE_MAX,
+	.output_max_size = SIZE_MAX,
+	.client = FALSE
+};
+
+static const struct connection_vfuncs client_vfuncs = {
+	.destroy = imap_master_client_destroy,
+	.input_line = imap_master_client_input_line
+};
+
+void imap_master_clients_init(void)
+{
+	master_clients = connection_list_init(&client_set, &client_vfuncs);
+}
+
+void imap_master_clients_deinit(void)
+{
+	connection_list_deinit(&master_clients);
+}
diff --git a/src/imap/imap-master-client.h b/src/imap/imap-master-client.h
new file mode 100644
index 0000000..478a64a
--- /dev/null
+++ b/src/imap/imap-master-client.h
@@ -0,0 +1,9 @@
+#ifndef IMAP_MASTER_CLIENT_H
+#define IMAP_MASTER_CLIENT_H
+
+void imap_master_client_create(int fd);
+
+void imap_master_clients_init(void);
+void imap_master_clients_deinit(void);
+
+#endif
diff --git a/src/imap/imap-notify.c b/src/imap/imap-notify.c
new file mode 100644
index 0000000..fa2c9ef
--- /dev/null
+++ b/src/imap/imap-notify.c
@@ -0,0 +1,523 @@
+/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "ostream.h"
+#include "imap-quote.h"
+#include "mailbox-list-iter.h"
+#include "mailbox-list-notify.h"
+#include "mail-search.h"
+#include "mail-search-build.h"
+#include "imap-commands.h"
+#include "imap-fetch.h"
+#include "imap-list.h"
+#include "imap-status.h"
+#include "imap-notify.h"
+
+#define IMAP_NOTIFY_WATCH_ADD_DELAY_MSECS 1000
+
+static int imap_notify_list(struct imap_notify_namespace *notify_ns,
+			    const struct mailbox_list_notify_rec *rec,
+			    enum mailbox_info_flags flags)
+{
+	string_t *str = t_str_new(128);
+	char ns_sep = mail_namespace_get_sep(notify_ns->ns);
+
+	str_append(str, "* LIST (");
+	imap_mailbox_flags2str(str, flags);
+	str_append(str, ") \"");
+	if (ns_sep == '\\')
+		str_append_c(str, '\\');
+	str_append_c(str, ns_sep);
+	str_append(str, "\" ");
+
+	imap_append_astring(str, rec->vname);
+	if (rec->old_vname != NULL) {
+		str_append(str, " (\"OLDNAME\" (");
+		imap_append_astring(str, rec->old_vname);
+		str_append(str, "))");
+	}
+	return client_send_line_next(notify_ns->ctx->client, str_c(str));
+}
+
+static int imap_notify_status(struct imap_notify_namespace *notify_ns,
+			      const struct mailbox_list_notify_rec *rec)
+{
+	struct client *client = notify_ns->ctx->client;
+	struct mailbox *box;
+	struct imap_status_items items;
+	struct imap_status_result result;
+	enum mail_error error;
+	int ret = 1;
+
+	i_zero(&items);
+	if (client_has_enabled(client, imap_feature_condstore))
+		items.flags |= IMAP_STATUS_ITEM_HIGHESTMODSEQ;
+
+	box = mailbox_alloc(notify_ns->ns->list, rec->vname, 0);
+	if ((rec->events & MAILBOX_LIST_NOTIFY_UIDVALIDITY) != 0) {
+		items.flags |= IMAP_STATUS_ITEM_UIDVALIDITY |
+			IMAP_STATUS_ITEM_UIDNEXT | IMAP_STATUS_ITEM_MESSAGES |
+			IMAP_STATUS_ITEM_UNSEEN;
+	}
+	if ((rec->events & (MAILBOX_LIST_NOTIFY_APPENDS |
+			    MAILBOX_LIST_NOTIFY_EXPUNGES)) != 0)
+		items.flags |= IMAP_STATUS_ITEM_UIDNEXT |
+			IMAP_STATUS_ITEM_MESSAGES | IMAP_STATUS_ITEM_UNSEEN;
+	if ((rec->events & MAILBOX_LIST_NOTIFY_SEEN_CHANGES) != 0)
+		items.flags |= IMAP_STATUS_ITEM_UNSEEN;
+	if ((rec->events & MAILBOX_LIST_NOTIFY_MODSEQ_CHANGES) != 0) {
+		/* if HIGHESTMODSEQ isn't being sent, don't send anything */
+	}
+	if (imap_status_items_is_empty(&items)) {
+		/* don't send anything */
+	} else if (imap_status_get_result(client, box, &items, &result) < 0) {
+		/* hide permission errors from client. we don't want to leak
+		   information about existence of mailboxes where user doesn't
+		   have access to */
+		(void)mailbox_get_last_error(box, &error);
+		if (error != MAIL_ERROR_PERM)
+			ret = -1;
+	} else {
+		ret = imap_status_send(client, rec->vname, &items, &result);
+	}
+	mailbox_free(&box);
+	return ret;
+}
+
+static int
+imap_notify_next(struct imap_notify_namespace *notify_ns,
+		 const struct mailbox_list_notify_rec *rec)
+{
+	enum mailbox_info_flags mailbox_flags;
+	int ret;
+
+	if ((rec->events & MAILBOX_LIST_NOTIFY_CREATE) != 0) {
+		if (mailbox_list_mailbox(notify_ns->ns->list, rec->storage_name,
+					 &mailbox_flags) < 0)
+			mailbox_flags = 0;
+		if ((ret = imap_notify_list(notify_ns, rec, mailbox_flags)) <= 0)
+			return ret;
+	}
+	if ((rec->events & MAILBOX_LIST_NOTIFY_DELETE) != 0) {
+		if ((ret = imap_notify_list(notify_ns, rec, MAILBOX_NONEXISTENT)) < 0)
+			return ret;
+	}
+	if ((rec->events & MAILBOX_LIST_NOTIFY_RENAME) != 0) {
+		if (mailbox_list_mailbox(notify_ns->ns->list, rec->storage_name,
+					 &mailbox_flags) < 0)
+			mailbox_flags = 0;
+		if ((ret = imap_notify_list(notify_ns, rec, mailbox_flags)) < 0)
+			return ret;
+	}
+	if ((rec->events & MAILBOX_LIST_NOTIFY_SUBSCRIBE) != 0) {
+		if (mailbox_list_mailbox(notify_ns->ns->list, rec->storage_name,
+					 &mailbox_flags) < 0)
+			mailbox_flags = 0;
+		if ((ret = imap_notify_list(notify_ns, rec,
+				     mailbox_flags | MAILBOX_SUBSCRIBED)) < 0)
+			return ret;
+	}
+	if ((rec->events & MAILBOX_LIST_NOTIFY_UNSUBSCRIBE) != 0) {
+		if (mailbox_list_mailbox(notify_ns->ns->list, rec->storage_name,
+					 &mailbox_flags) < 0)
+			mailbox_flags = 0;
+		if ((ret = imap_notify_list(notify_ns, rec, mailbox_flags)) < 0)
+			return ret;
+	}
+	if ((rec->events & (MAILBOX_LIST_NOTIFY_UIDVALIDITY |
+			    MAILBOX_LIST_NOTIFY_APPENDS |
+			    MAILBOX_LIST_NOTIFY_EXPUNGES |
+			    MAILBOX_LIST_NOTIFY_SEEN_CHANGES |
+			    MAILBOX_LIST_NOTIFY_MODSEQ_CHANGES)) != 0) {
+		if ((ret = imap_notify_status(notify_ns, rec)) < 0)
+			return ret;
+	}
+	return 1;
+}
+
+static bool
+imap_notify_match_event(struct imap_notify_namespace *notify_ns,
+			const struct imap_notify_mailboxes *notify_boxes,
+			const struct mailbox_list_notify_rec *rec)
+{
+	enum imap_notify_event wanted_events = notify_boxes->events;
+	struct mailbox *box;
+
+	/* check for mailbox list events first */
+	if ((wanted_events & IMAP_NOTIFY_EVENT_MAILBOX_NAME) != 0) {
+		if ((rec->events & (MAILBOX_LIST_NOTIFY_CREATE |
+				    MAILBOX_LIST_NOTIFY_DELETE |
+				    MAILBOX_LIST_NOTIFY_RENAME)) != 0)
+			return TRUE;
+	}
+	if ((wanted_events & IMAP_NOTIFY_EVENT_SUBSCRIPTION_CHANGE) != 0) {
+		if ((rec->events & (MAILBOX_LIST_NOTIFY_SUBSCRIBE |
+				    MAILBOX_LIST_NOTIFY_UNSUBSCRIBE)) != 0)
+			return TRUE;
+	}
+
+	/* if this is an event for the selected mailbox, ignore it */
+	box = notify_ns->ctx->client->mailbox;
+	if (box != NULL && mailbox_equals(box, notify_ns->ns, rec->vname))
+		return FALSE;
+
+	if ((wanted_events & (IMAP_NOTIFY_EVENT_MESSAGE_NEW |
+			      IMAP_NOTIFY_EVENT_MESSAGE_EXPUNGE |
+			      IMAP_NOTIFY_EVENT_FLAG_CHANGE)) != 0) {
+		if ((rec->events & MAILBOX_LIST_NOTIFY_UIDVALIDITY) != 0)
+			return TRUE;
+	}
+	if ((wanted_events & IMAP_NOTIFY_EVENT_MESSAGE_NEW) != 0) {
+		if ((rec->events & MAILBOX_LIST_NOTIFY_APPENDS) != 0)
+			return TRUE;
+	}
+	if ((wanted_events & IMAP_NOTIFY_EVENT_MESSAGE_EXPUNGE) != 0) {
+		if ((rec->events & MAILBOX_LIST_NOTIFY_EXPUNGES) != 0)
+			return TRUE;
+	}
+	if ((wanted_events & IMAP_NOTIFY_EVENT_FLAG_CHANGE) != 0) {
+		if ((rec->events & (MAILBOX_LIST_NOTIFY_SEEN_CHANGES |
+				    MAILBOX_LIST_NOTIFY_MODSEQ_CHANGES)) != 0)
+			return TRUE;
+	}
+	return FALSE;
+}
+
+bool imap_notify_match_mailbox(struct imap_notify_namespace *notify_ns,
+			       const struct imap_notify_mailboxes *notify_boxes,
+			       const char *vname)
+{
+	struct mailbox *box;
+	const char *name;
+	size_t name_len;
+	char ns_sep;
+	bool ret;
+
+	switch (notify_boxes->type) {
+	case IMAP_NOTIFY_TYPE_SUBSCRIBED:
+		box = mailbox_alloc(notify_ns->ns->list, vname, 0);
+		ret = mailbox_is_subscribed(box);
+		mailbox_free(&box);
+		return ret;
+	case IMAP_NOTIFY_TYPE_SUBTREE:
+		ns_sep = mail_namespace_get_sep(notify_ns->ns);
+		array_foreach_elem(&notify_boxes->names, name) {
+			name_len = strlen(name);
+			if (name_len == 0) {
+				/* everything under root. NOTIFY spec itself
+				   doesn't define this, but we use it for
+				   implementing "personal" */
+				return TRUE;
+			}
+			if (str_begins(vname, name) &&
+			    (vname[name_len] == '\0' ||
+			     vname[name_len] == ns_sep))
+				return TRUE;
+		}
+		break;
+	case IMAP_NOTIFY_TYPE_MAILBOX:
+		array_foreach_elem(&notify_boxes->names, name) {
+			if (strcmp(name, vname) == 0)
+				return TRUE;
+		}
+		break;
+	}
+	return FALSE;
+}
+
+static bool
+imap_notify_match(struct imap_notify_namespace *notify_ns,
+		  const struct mailbox_list_notify_rec *rec)
+{
+	const struct imap_notify_mailboxes *notify_boxes;
+
+	array_foreach(&notify_ns->mailboxes, notify_boxes) {
+		if (imap_notify_match_event(notify_ns, notify_boxes, rec) &&
+		    imap_notify_match_mailbox(notify_ns, notify_boxes, rec->vname))
+			return TRUE;
+	}
+	return FALSE;
+}
+
+static int imap_client_notify_ns(struct imap_notify_namespace *notify_ns)
+{
+	const struct mailbox_list_notify_rec *rec;
+	int ret, ret2 = 1;
+
+	if (notify_ns->notify == NULL)
+		return 0; /* notifications not supported in this namespace */
+
+	while ((ret = mailbox_list_notify_next(notify_ns->notify, &rec)) > 0) {
+		if (imap_notify_match(notify_ns, rec)) T_BEGIN {
+			ret2 = imap_notify_next(notify_ns, rec);
+		} T_END;
+		if (ret2 <= 0)
+			break;
+	}
+	if (ret < 0) {
+		/* failed to get some notifications */
+		return -1;
+	}
+	return ret2;
+}
+
+static int
+imap_client_notify_selected(struct client *client)
+{
+	struct imap_fetch_context *fetch_ctx = client->notify_ctx->fetch_ctx;
+	int ret;
+
+	if (!fetch_ctx->state.fetching)
+		return 1;
+
+	if ((ret = imap_fetch_more_no_lock_update(fetch_ctx)) == 0)
+		return 0;
+	/* finished the FETCH */
+	if (imap_fetch_end(fetch_ctx) < 0)
+		return -1;
+	return ret;
+}
+
+static int imap_client_notify_more(struct client *client)
+{
+	struct imap_notify_namespace *notify_ns;
+	int ret = 1;
+
+	struct event_reason *reason = event_reason_begin("imap:notify_update");
+
+	/* send notifications for selected mailbox first. note that it may
+	   leave the client's output stream in the middle of a FETCH reply. */
+	if (client->notify_ctx->fetch_ctx != NULL) {
+		if ((ret = imap_client_notify_selected(client)) < 0) {
+			client->notify_ctx->fetch_ctx->state.failed = FALSE;
+			ret = -1;
+		}
+	}
+
+	/* send notifications for non-selected mailboxes */
+	array_foreach_modifiable(&client->notify_ctx->namespaces, notify_ns) {
+		if (ret == 0)
+			break;
+		if (imap_client_notify_ns(notify_ns) < 0)
+			ret = -1;
+	}
+
+	if (ret < 0) {
+		client_send_line(client,
+			"* NO NOTIFY error, some events may have got lost");
+	}
+	event_reason_end(&reason);
+	return ret;
+}
+
+int imap_client_notify_newmails(struct client *client)
+{
+	struct imap_fetch_context *fetch_ctx = client->notify_ctx->fetch_ctx;
+	struct mailbox_status status;
+	struct mail_search_args *search_args;
+	struct mail_search_arg *arg;
+
+	i_assert(client->mailbox != NULL);
+
+	if (fetch_ctx == NULL) {
+		/* FETCH notifications not enabled in this session */
+		return 1;
+	}
+	if (client->notify_ctx->notifying)
+		return imap_client_notify_more(client);
+	client->notify_ctx->notifying = TRUE;
+
+	i_assert(!fetch_ctx->state.fetching);
+
+	mailbox_get_open_status(client->mailbox, STATUS_UIDNEXT, &status);
+
+	search_args = mail_search_build_init();
+	arg = mail_search_build_add(search_args, SEARCH_UIDSET);
+	p_array_init(&arg->value.seqset, search_args->pool, 1);
+	seq_range_array_add_range(&arg->value.seqset,
+				  client->notify_uidnext, status.uidnext-1);
+	client->notify_uidnext = status.uidnext;
+
+	imap_fetch_begin(fetch_ctx, client->mailbox, search_args);
+	mail_search_args_unref(&search_args);
+
+	return imap_client_notify_more(client);
+}
+
+void imap_client_notify_finished(struct client *client)
+{
+	if (client->notify_ctx != NULL)
+		client->notify_ctx->notifying = FALSE;
+}
+
+static void notify_callback(struct imap_notify_namespace *notify_ns)
+{
+	struct event_reason *reason = event_reason_begin("imap:notify_update");
+	o_stream_cork(notify_ns->ctx->client->output);
+	imap_client_notify_ns(notify_ns);
+	o_stream_uncork(notify_ns->ctx->client->output);
+	event_reason_end(&reason);
+}
+
+static enum mailbox_list_notify_event
+imap_events_to_notify(enum imap_notify_event events)
+{
+	enum mailbox_list_notify_event ret = 0;
+
+	if ((events & IMAP_NOTIFY_EVENT_MESSAGE_NEW) != 0) {
+		ret |= MAILBOX_LIST_NOTIFY_APPENDS |
+			MAILBOX_LIST_NOTIFY_UIDVALIDITY;
+	}
+	if ((events & IMAP_NOTIFY_EVENT_MESSAGE_EXPUNGE) != 0) {
+		ret |= MAILBOX_LIST_NOTIFY_EXPUNGES |
+			MAILBOX_LIST_NOTIFY_UIDVALIDITY;
+	}
+	if ((events & IMAP_NOTIFY_EVENT_FLAG_CHANGE) != 0) {
+		ret |= MAILBOX_LIST_NOTIFY_SEEN_CHANGES |
+			MAILBOX_LIST_NOTIFY_MODSEQ_CHANGES |
+			MAILBOX_LIST_NOTIFY_UIDVALIDITY;
+	}
+	if ((events & IMAP_NOTIFY_EVENT_MAILBOX_NAME) != 0) {
+		ret |= MAILBOX_LIST_NOTIFY_CREATE |
+			MAILBOX_LIST_NOTIFY_DELETE |
+			MAILBOX_LIST_NOTIFY_RENAME;
+	}
+	if ((events & IMAP_NOTIFY_EVENT_SUBSCRIPTION_CHANGE) != 0) {
+		ret |= MAILBOX_LIST_NOTIFY_SUBSCRIBE |
+			MAILBOX_LIST_NOTIFY_UNSUBSCRIBE;
+	}
+	return ret;
+}
+
+static void imap_notify_callback(struct mailbox *box, struct client *client)
+{
+	struct client_command_context *cmd;
+	enum mailbox_sync_flags sync_flags = 0;
+
+	i_assert(client->command_queue_size == 0);
+	i_assert(box == client->mailbox);
+
+	/* create a fake command to handle this */
+	cmd = client_command_alloc(client);
+	cmd->tag = "*";
+	cmd->name = "NOTIFY-CALLBACK";
+	client_command_init_finished(cmd);
+
+	if (!client->notify_ctx->selected_immediate_expunges)
+		sync_flags |= MAILBOX_SYNC_FLAG_NO_EXPUNGES;
+	if (cmd_sync(cmd, sync_flags, 0, NULL))
+		i_unreached();
+	(void)cmd_sync_delayed(client);
+}
+
+static void imap_notify_watch_selected_mailbox(struct client *client)
+{
+	i_assert(client->command_queue_size == 0);
+
+	if (client->mailbox == NULL) {
+		/* mailbox not selected */
+		return;
+	}
+	if (client->notify_ctx == NULL || !client->notify_ctx->selected_set) {
+		/* client doesn't want selected mailbox notifications */
+		return;
+
+	}
+	mailbox_notify_changes(client->mailbox, imap_notify_callback, client);
+	client->notify_ctx->watching_mailbox = TRUE;
+}
+
+static void imap_notify_watch_timeout(struct client *client)
+{
+	timeout_remove(&client->notify_ctx->to_watch);
+	imap_notify_watch_selected_mailbox(client);
+}
+
+void imap_client_notify_command_freed(struct client *client)
+{
+	struct imap_notify_context *ctx = client->notify_ctx;
+
+	if (ctx == NULL)
+		return;
+
+	if (client->command_queue_size > 0) {
+		/* don't add it until all commands are finished */
+		i_assert(ctx->to_watch == NULL);
+		return;
+	}
+
+	/* add mailbox watch back after a small delay. if another command
+	   is started this timeout is aborted. */
+	ctx->to_watch = timeout_add(IMAP_NOTIFY_WATCH_ADD_DELAY_MSECS,
+				    imap_notify_watch_timeout, client);
+}
+
+void imap_client_notify_command_allocated(struct client *client)
+{
+	struct imap_notify_context *ctx = client->notify_ctx;
+
+	if (ctx == NULL)
+		return;
+
+	/* remove mailbox watcher before starting any commands */
+	if (ctx->watching_mailbox) {
+		mailbox_notify_changes_stop(client->mailbox);
+		ctx->watching_mailbox = FALSE;
+	}
+	timeout_remove(&ctx->to_watch);
+}
+
+int imap_notify_begin(struct imap_notify_context *ctx)
+{
+	struct imap_notify_namespace *notify_ns;
+	const struct imap_notify_mailboxes *notify_boxes;
+	enum mailbox_list_notify_event notify_events;
+	int ret = -1;
+
+	array_foreach_modifiable(&ctx->namespaces, notify_ns) {
+		notify_events = 0;
+		array_foreach(&notify_ns->mailboxes, notify_boxes) {
+			notify_events |=
+				imap_events_to_notify(notify_boxes->events);
+		}
+		if (mailbox_list_notify_init(notify_ns->ns->list, notify_events,
+					     &notify_ns->notify) < 0) {
+			/* notifications not supported */
+		} else {
+			ret = 0;
+			mailbox_list_notify_wait(notify_ns->notify,
+						 notify_callback, notify_ns);
+		}
+	}
+	/* enable NOTIFY as long as even one namespace supports it,
+	   ignore the rest */
+	return ret;
+}
+
+void imap_notify_deinit(struct imap_notify_context **_ctx)
+{
+	struct imap_notify_context *ctx = *_ctx;
+	struct imap_notify_namespace *notify_ns;
+
+	*_ctx = NULL;
+
+	array_foreach_modifiable(&ctx->namespaces, notify_ns) {
+		if (notify_ns->notify != NULL)
+			mailbox_list_notify_deinit(&notify_ns->notify);
+	}
+	timeout_remove(&ctx->to_watch);
+	if (ctx->fetch_ctx != NULL)
+		imap_fetch_free(&ctx->fetch_ctx);
+	pool_unref(&ctx->pool);
+}
+
+void imap_notify_flush(struct imap_notify_context *ctx)
+{
+	struct imap_notify_namespace *notify_ns;
+
+	array_foreach_modifiable(&ctx->namespaces, notify_ns) {
+		if (notify_ns->notify != NULL)
+			mailbox_list_notify_flush(notify_ns->notify);
+	}
+}
diff --git a/src/imap/imap-notify.h b/src/imap/imap-notify.h
new file mode 100644
index 0000000..936d622
--- /dev/null
+++ b/src/imap/imap-notify.h
@@ -0,0 +1,75 @@
+#ifndef IMAP_NOTIFY_H
+#define IMAP_NOTIFY_H
+
+enum imap_notify_type {
+	IMAP_NOTIFY_TYPE_SUBSCRIBED,
+	IMAP_NOTIFY_TYPE_SUBTREE,
+	IMAP_NOTIFY_TYPE_MAILBOX
+};
+
+enum imap_notify_event {
+	IMAP_NOTIFY_EVENT_MESSAGE_NEW		= 0x01,
+	IMAP_NOTIFY_EVENT_MESSAGE_EXPUNGE	= 0x02,
+	IMAP_NOTIFY_EVENT_FLAG_CHANGE		= 0x04,
+	IMAP_NOTIFY_EVENT_ANNOTATION_CHANGE	= 0x08,
+	IMAP_NOTIFY_EVENT_MAILBOX_NAME		= 0x10,
+	IMAP_NOTIFY_EVENT_SUBSCRIPTION_CHANGE	= 0x20,
+	IMAP_NOTIFY_EVENT_MAILBOX_METADATA_CHANGE = 0x40,
+	IMAP_NOTIFY_EVENT_SERVER_METADATA_CHANGE = 0x80
+};
+#define UNSUPPORTED_EVENTS \
+	(IMAP_NOTIFY_EVENT_ANNOTATION_CHANGE | \
+	 IMAP_NOTIFY_EVENT_MAILBOX_METADATA_CHANGE | \
+	 IMAP_NOTIFY_EVENT_SERVER_METADATA_CHANGE)
+
+struct imap_notify_mailboxes {
+	enum imap_notify_event events;
+	enum imap_notify_type type;
+	ARRAY_TYPE(const_string) names;
+};
+
+struct imap_notify_namespace {
+	struct imap_notify_context *ctx;
+	struct mail_namespace *ns;
+
+	struct mailbox_list_notify *notify;
+	ARRAY(struct imap_notify_mailboxes) mailboxes;
+};
+
+struct imap_notify_context {
+	pool_t pool;
+	struct client *client;
+	const char *error;
+
+	ARRAY(struct imap_notify_namespace) namespaces;
+	enum imap_notify_event selected_events;
+	enum imap_notify_event global_used_events;
+	unsigned int global_max_mailbox_names;
+
+	struct imap_fetch_context *fetch_ctx;
+	struct timeout *to_watch;
+
+	bool have_subscriptions:1;
+	bool selected_set:1;
+	bool selected_immediate_expunges:1;
+	bool send_immediate_status:1;
+	bool watching_mailbox:1;
+	bool notifying:1;
+};
+
+bool imap_notify_match_mailbox(struct imap_notify_namespace *notify_ns,
+			       const struct imap_notify_mailboxes *notify_boxes,
+			       const char *vname);
+
+int imap_client_notify_newmails(struct client *client);
+void imap_client_notify_finished(struct client *client);
+
+void imap_client_notify_command_allocated(struct client *client);
+void imap_client_notify_command_freed(struct client *client);
+
+int imap_notify_begin(struct imap_notify_context *ctx);
+void imap_notify_deinit(struct imap_notify_context **ctx);
+
+void imap_notify_flush(struct imap_notify_context *ctx);
+
+#endif
diff --git a/src/imap/imap-search-args.c b/src/imap/imap-search-args.c
new file mode 100644
index 0000000..67e8679
--- /dev/null
+++ b/src/imap/imap-search-args.c
@@ -0,0 +1,353 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "mail-storage.h"
+#include "mail-search-parser.h"
+#include "mail-search-build.h"
+#include "imap-search-args.h"
+#include "imap-parser.h"
+#include "imap-seqset.h"
+
+
+struct search_build_data {
+	pool_t pool;
+        struct mailbox *box;
+	const char *error;
+};
+
+static bool search_args_have_searchres(struct mail_search_arg *sargs)
+{
+	for (; sargs != NULL; sargs = sargs->next) {
+		switch (sargs->type) {
+		case SEARCH_UIDSET:
+			if (strcmp(sargs->value.str, "$") == 0)
+				return TRUE;
+			break;
+		case SEARCH_SUB:
+		case SEARCH_OR:
+			if (search_args_have_searchres(sargs->value.subargs))
+				return TRUE;
+			break;
+		default:
+			break;
+		}
+	}
+	return FALSE;
+}
+
+static void imap_search_saved_uidset_clear(struct client_command_context *cmd)
+{
+	if (array_is_created(&cmd->client->search_saved_uidset))
+		array_clear(&cmd->client->search_saved_uidset);
+	else
+		i_array_init(&cmd->client->search_saved_uidset, 128);
+}
+
+int imap_search_args_build(struct client_command_context *cmd,
+			   const struct imap_arg *args, const char *charset,
+			   struct mail_search_args **search_args_r)
+{
+	struct mail_search_parser *parser;
+	struct mail_search_args *sargs;
+	const char *client_error;
+	int ret;
+
+	if (IMAP_ARG_IS_EOL(args)) {
+		client_send_command_error(cmd, "Missing search parameters");
+		return -1;
+	}
+
+	parser = mail_search_parser_init_imap(args);
+	ret = mail_search_build(mail_search_register_get_imap(),
+				parser, &charset, &sargs, &client_error);
+	mail_search_parser_deinit(&parser);
+	if (ret < 0) {
+		if (charset == NULL) {
+			if (cmd->search_save_result)
+				imap_search_saved_uidset_clear(cmd);
+			client_send_tagline(cmd, t_strconcat(
+				"NO [BADCHARSET] ", client_error, NULL));
+		} else {
+			client_send_command_error(cmd, client_error);
+		}
+		return -1;
+	}
+
+	if (search_args_have_searchres(sargs->args)) {
+		if (client_handle_search_save_ambiguity(cmd))
+			return 0;
+	}
+
+	mail_search_args_init(sargs, cmd->client->mailbox, TRUE,
+			      &cmd->client->search_saved_uidset);
+	if (cmd->search_save_result) {
+		/* clear the SAVE resultset only after potentially using $
+		   in the search args themselves */
+		imap_search_saved_uidset_clear(cmd);
+	}
+	*search_args_r = sargs;
+	return 1;
+}
+
+static bool
+msgset_is_valid(ARRAY_TYPE(seq_range) *seqset, uint32_t messages_count)
+{
+	const struct seq_range *range;
+	unsigned int count;
+
+	/* when there are no messages, all messagesets are invalid.
+	   if there's at least one message:
+	    - * gives seq1 = seq2 = (uint32_t)-1
+	    - n:* should work if n <= messages_count
+	    - n:m or m should work if m <= messages_count
+	*/
+	range = array_get(seqset, &count);
+	if (count == 0 || messages_count == 0)
+		return FALSE;
+
+	if (range[count-1].seq2 == (uint32_t)-1) {
+		if (range[count-1].seq1 > messages_count &&
+		    range[count-1].seq1 != (uint32_t)-1)
+			return FALSE;
+	} else {
+		if (range[count-1].seq2 > messages_count)
+			return FALSE;
+	}
+	return TRUE;
+}
+
+static int imap_search_get_msgset_arg(struct client_command_context *cmd,
+				      const char *messageset,
+				      struct mail_search_args **args_r,
+				      const char **error_r)
+{
+	struct mail_search_args *args;
+
+	args = mail_search_build_init();
+	args->args = p_new(args->pool, struct mail_search_arg, 1);
+	args->args->type = SEARCH_SEQSET;
+	p_array_init(&args->args->value.seqset, args->pool, 16);
+	if (imap_seq_set_parse(messageset, &args->args->value.seqset) < 0 ||
+	    !msgset_is_valid(&args->args->value.seqset,
+			     cmd->client->messages_count)) {
+		*error_r = "Invalid messageset";
+		mail_search_args_unref(&args);
+		return -1;
+	}
+	*args_r = args;
+	return 0;
+}
+
+static int
+imap_search_get_uidset_arg(const char *uidset, struct mail_search_args **args_r,
+			   const char **error_r)
+{
+	struct mail_search_args *args;
+
+	args = mail_search_build_init();
+	args->args = p_new(args->pool, struct mail_search_arg, 1);
+	args->args->type = SEARCH_UIDSET;
+	p_array_init(&args->args->value.seqset, args->pool, 16);
+	if (imap_seq_set_parse(uidset, &args->args->value.seqset) < 0) {
+		*error_r = "Invalid uidset";
+		mail_search_args_unref(&args);
+		return -1;
+	}
+
+	*args_r = args;
+	return 0;
+}
+
+int imap_search_get_seqset(struct client_command_context *cmd,
+			   const char *set, bool uid,
+			   struct mail_search_args **search_args_r)
+{
+	int ret;
+
+	ret = imap_search_get_anyset(cmd, set, uid, search_args_r);
+	if (ret > 0) {
+		mail_search_args_init(*search_args_r,
+				      cmd->client->mailbox, TRUE,
+				      &cmd->client->search_saved_uidset);
+	}
+	return ret;
+}
+
+void imap_search_anyset_to_uidset(struct client_command_context *cmd,
+				  struct mail_search_args *args)
+{
+	struct mail_search_arg *arg = args->args;
+
+	i_assert(arg->next == NULL);
+	switch (arg->type) {
+	case SEARCH_ALL:
+		if (arg->match_not)
+			break;
+		t_array_init(&arg->value.seqset, 1);
+		seq_range_array_add_range(&arg->value.seqset, 1, (uint32_t)-1);
+		/* fall through */
+	case SEARCH_SEQSET: {
+		ARRAY_TYPE(seq_range) seqs = arg->value.seqset;
+
+		arg->type = SEARCH_UIDSET;
+		p_array_init(&arg->value.seqset, args->pool, 16);
+		mailbox_get_uid_range(cmd->client->mailbox, &seqs,
+				      &arg->value.seqset);
+		break;
+	}
+	case SEARCH_UIDSET:
+		break;
+	default:
+		i_unreached();
+	}
+}
+
+static int imap_search_get_searchres(struct client_command_context *cmd,
+				     struct mail_search_args **search_args_r)
+{
+	struct mail_search_args *search_args;
+
+	if (client_handle_search_save_ambiguity(cmd))
+		return 0;
+
+	search_args = mail_search_build_init();
+	search_args->args = p_new(search_args->pool, struct mail_search_arg, 1);
+	if (array_is_created(&cmd->client->search_saved_uidset)) {
+		search_args->args->type = SEARCH_UIDSET;
+		p_array_init(&search_args->args->value.seqset,
+			     search_args->pool,
+			     array_count(&cmd->client->search_saved_uidset));
+		array_append_array(&search_args->args->value.seqset,
+				   &cmd->client->search_saved_uidset);
+	} else {
+		/* $ not set yet, match nothing */
+		search_args->args->type = SEARCH_ALL;
+		search_args->args->match_not = TRUE;
+	}
+	*search_args_r = search_args;
+	return 1;
+}
+
+int imap_search_get_anyset(struct client_command_context *cmd,
+			   const char *set, bool uid,
+			   struct mail_search_args **search_args_r)
+{
+	const char *client_error = NULL;
+	int ret;
+
+	if (strcmp(set, "$") == 0) {
+		/* SEARCHRES extension: replace $ with the last saved
+		   search result */
+		return imap_search_get_searchres(cmd, search_args_r);
+	}
+	if (!uid) {
+		ret = imap_search_get_msgset_arg(cmd, set, search_args_r,
+						 &client_error);
+	} else {
+		ret = imap_search_get_uidset_arg(set, search_args_r,
+						 &client_error);
+	}
+	if (ret < 0) {
+		client_send_command_error(cmd, client_error);
+		return -1;
+	}
+	return 1;
+}
+
+void imap_search_add_changed_since(struct mail_search_args *search_args,
+				   uint64_t modseq)
+{
+	struct mail_search_arg *search_arg;
+
+	search_arg = p_new(search_args->pool, struct mail_search_arg, 1);
+	search_arg->type = SEARCH_MODSEQ;
+	search_arg->value.modseq =
+		p_new(search_args->pool, struct mail_search_modseq, 1);
+	search_arg->value.modseq->modseq = modseq + 1;
+
+	search_arg->next = search_args->args->next;
+	search_args->args->next = search_arg;
+}
+
+struct imap_search_seqset_iter {
+	struct mail_search_args *search_args;
+	ARRAY_TYPE(seq_range) seqset_left;
+	unsigned int batch_size;
+};
+
+static void imap_search_seqset_next_batch(struct imap_search_seqset_iter *iter)
+{
+	array_clear(&iter->search_args->args->value.seqset);
+	seq_range_array_merge_n(&iter->search_args->args->value.seqset,
+				&iter->seqset_left, iter->batch_size);
+}
+
+struct imap_search_seqset_iter *
+imap_search_seqset_iter_init(struct mail_search_args *search_args,
+			     uint32_t messages_count, unsigned int batch_size)
+{
+	struct imap_search_seqset_iter *iter;
+
+	i_assert(search_args->args->next == NULL);
+
+	iter = i_new(struct imap_search_seqset_iter, 1);
+	iter->search_args = search_args;
+	iter->batch_size = batch_size;
+	mail_search_args_ref(iter->search_args);
+
+	switch (search_args->args->type) {
+	case SEARCH_SEQSET:
+	case SEARCH_UIDSET:
+		break;
+	case SEARCH_ALL:
+		if (search_args->args->match_not) {
+			/* $ used before search result was saved */
+			return iter;
+		}
+		/* 1:* - convert to seqset */
+		search_args->args->type = SEARCH_SEQSET;
+		p_array_init(&search_args->args->value.seqset,
+			     search_args->pool, 1);
+		seq_range_array_add_range(&search_args->args->value.seqset,
+					  1, messages_count);
+		break;
+	default:
+		i_panic("Unexpected search_args type %d",
+			search_args->args->type);
+	}
+
+	i_assert(search_args->args->type == SEARCH_SEQSET ||
+		 search_args->args->type == SEARCH_UIDSET);
+
+	i_array_init(&iter->seqset_left,
+		     array_count(&search_args->args->value.seqset));
+	array_append_array(&iter->seqset_left, &search_args->args->value.seqset);
+	imap_search_seqset_next_batch(iter);
+	return iter;
+}
+
+void imap_search_seqset_iter_deinit(struct imap_search_seqset_iter **_iter)
+{
+	struct imap_search_seqset_iter *iter = *_iter;
+
+	if (iter == NULL)
+		return;
+
+	mail_search_args_unref(&iter->search_args);
+	array_free(&iter->seqset_left);
+	i_free(iter);
+}
+
+bool imap_search_seqset_iter_next(struct imap_search_seqset_iter *iter)
+{
+	if (!array_is_created(&iter->seqset_left) ||
+	    array_count(&iter->seqset_left) == 0)
+		return FALSE;
+
+	/* remove the last batch of searched mails from seqset_left */
+	if (seq_range_array_remove_seq_range(&iter->seqset_left,
+			&iter->search_args->args->value.seqset) == 0)
+		i_unreached();
+	imap_search_seqset_next_batch(iter);
+	return array_count(&iter->search_args->args->value.seqset) > 0;
+}
diff --git a/src/imap/imap-search-args.h b/src/imap/imap-search-args.h
new file mode 100644
index 0000000..4bf6c4c
--- /dev/null
+++ b/src/imap/imap-search-args.h
@@ -0,0 +1,47 @@
+#ifndef IMAP_SEARCH_ARGS_H
+#define IMAP_SEARCH_ARGS_H
+
+#include "mail-search.h"
+
+struct imap_arg;
+struct mailbox;
+struct client_command_context;
+
+/* Builds search arguments based on IMAP arguments. Returns -1 if search
+   arguments are invalid, 0 if we have to wait for unambiguity,
+   1 if we can continue. */
+int imap_search_args_build(struct client_command_context *cmd,
+			   const struct imap_arg *args, const char *charset,
+			   struct mail_search_args **search_args_r);
+
+/* Returns -1 if set is invalid, 0 if we have to wait for unambiguity,
+   1 if we were successful. search_args_r is set to contain either a seqset
+   or uidset. */
+int imap_search_get_anyset(struct client_command_context *cmd,
+			   const char *set, bool uid,
+			   struct mail_search_args **search_args_r);
+/* Like imap_search_get_anyset(), but always returns a seqset. */
+int imap_search_get_seqset(struct client_command_context *cmd,
+			   const char *set, bool uid,
+			   struct mail_search_args **search_args_r);
+/* Convert search args returned by imap_search_get_anyset() to SEARCH_UIDSET. */
+void imap_search_anyset_to_uidset(struct client_command_context *cmd,
+				  struct mail_search_args *args);
+
+void imap_search_add_changed_since(struct mail_search_args *search_args,
+				   uint64_t modseq);
+
+/* Iterate search_args in batches of messages. The search_args itself is
+   modified each time imap_search_seqset_iter_next() is called. Note that
+   search_args is expected to come from imap_search_get_anyset(), so it should
+   have a single parameter containing SEARCH_ALL, SEARCH_SEQSET or
+   SEARCH_UIDSET. */
+struct imap_search_seqset_iter *
+imap_search_seqset_iter_init(struct mail_search_args *search_args,
+			     uint32_t messages_count, unsigned int batch_size);
+/* Iterate the next batch. Returns TRUE if the batch was updated, FALSE if
+   all the batches have been iterated. */
+bool imap_search_seqset_iter_next(struct imap_search_seqset_iter *iter);
+void imap_search_seqset_iter_deinit(struct imap_search_seqset_iter **iter);
+
+#endif
diff --git a/src/imap/imap-search.c b/src/imap/imap-search.c
new file mode 100644
index 0000000..8b5d660
--- /dev/null
+++ b/src/imap/imap-search.c
@@ -0,0 +1,612 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "ostream.h"
+#include "str.h"
+#include "seq-range-array.h"
+#include "time-util.h"
+#include "imap-resp-code.h"
+#include "imap-quote.h"
+#include "imap-seqset.h"
+#include "imap-util.h"
+#include "mail-search-build.h"
+#include "imap-fetch.h"
+#include "imap-commands.h"
+#include "imap-search-args.h"
+#include "imap-search.h"
+
+
+static int imap_search_deinit(struct imap_search_context *ctx);
+
+static int
+imap_partial_range_parse(struct imap_search_context *ctx, const char *str)
+{
+	ctx->partial1 = 0;
+	ctx->partial2 = 0;
+	for (; *str >= '0' && *str <= '9'; str++)
+		ctx->partial1 = ctx->partial1 * 10 + *str-'0';
+	if (*str != ':' || ctx->partial1 == 0)
+		return -1;
+	for (str++; *str >= '0' && *str <= '9'; str++)
+		ctx->partial2 = ctx->partial2 * 10 + *str-'0';
+	if (*str != '\0' || ctx->partial2 == 0)
+		return -1;
+
+	if (ctx->partial1 > ctx->partial2) {
+		uint32_t temp = ctx->partial2;
+		ctx->partial2 = ctx->partial1;
+		ctx->partial1 = temp;
+	}
+
+	return 0;
+}
+
+static bool
+search_parse_fetch_att(struct imap_search_context *ctx,
+		       const struct imap_arg *update_args)
+{
+	const char *client_error;
+
+	ctx->fetch_pool = pool_alloconly_create("search update fetch", 512);
+	if (imap_fetch_att_list_parse(ctx->cmd->client, ctx->fetch_pool,
+				      update_args, &ctx->fetch_ctx,
+				      &client_error) < 0) {
+		client_send_command_error(ctx->cmd, t_strconcat(
+			"SEARCH UPDATE fetch-att: ", client_error, NULL));
+		pool_unref(&ctx->fetch_pool);
+		return FALSE;
+	}
+	return TRUE;
+}
+
+static bool
+search_parse_return_options(struct imap_search_context *ctx,
+			    const struct imap_arg *args)
+{
+	struct client_command_context *cmd = ctx->cmd;
+	const struct imap_arg *update_args;
+	const char *name, *str;
+	unsigned int idx;
+
+	while (!IMAP_ARG_IS_EOL(args)) {
+		if (!imap_arg_get_atom(args, &name)) {
+			client_send_command_error(cmd,
+				"SEARCH return options contain non-atoms.");
+			return FALSE;
+		}
+		name = t_str_ucase(name);
+		args++;
+		if (strcmp(name, "MIN") == 0)
+			ctx->return_options |= SEARCH_RETURN_MIN;
+		else if (strcmp(name, "MAX") == 0)
+			ctx->return_options |= SEARCH_RETURN_MAX;
+		else if (strcmp(name, "ALL") == 0)
+			ctx->return_options |= SEARCH_RETURN_ALL;
+		else if (strcmp(name, "COUNT") == 0)
+			ctx->return_options |= SEARCH_RETURN_COUNT;
+		else if (strcmp(name, "SAVE") == 0)
+			ctx->return_options |= SEARCH_RETURN_SAVE;
+		else if (strcmp(name, "CONTEXT") == 0) {
+			/* no-op */
+		} else if (strcmp(name, "UPDATE") == 0) {
+			if ((ctx->return_options & SEARCH_RETURN_UPDATE) != 0) {
+				client_send_command_error(cmd,
+					"SEARCH return options have duplicate UPDATE.");
+				return FALSE;
+			}
+			ctx->return_options |= SEARCH_RETURN_UPDATE;
+			if (imap_arg_get_list(args, &update_args)) {
+				if (!search_parse_fetch_att(ctx, update_args))
+					return FALSE;
+				args++;
+			}
+		} else if (strcmp(name, "RELEVANCY") == 0)
+			ctx->return_options |= SEARCH_RETURN_RELEVANCY;
+		else if (strcmp(name, "PARTIAL") == 0) {
+			if (ctx->partial1 != 0) {
+				client_send_command_error(cmd,
+					"PARTIAL can be used only once.");
+				return FALSE;
+			}
+			ctx->return_options |= SEARCH_RETURN_PARTIAL;
+			if (!imap_arg_get_atom(args, &str)) {
+				client_send_command_error(cmd,
+					"PARTIAL range missing.");
+				return FALSE;
+			}
+			if (imap_partial_range_parse(ctx, str) < 0) {
+				client_send_command_error(cmd,
+					"PARTIAL range broken.");
+				return FALSE;
+			}
+			args++;
+		} else {
+			client_send_command_error(cmd,
+				"Unknown SEARCH return option");
+			return FALSE;
+		}
+	}
+
+	if ((ctx->return_options & SEARCH_RETURN_UPDATE) != 0 &&
+	    client_search_update_lookup(cmd->client, cmd->tag, &idx) != NULL) {
+		client_send_command_error(cmd, "Duplicate search update tag");
+		return FALSE;
+	}
+	if ((ctx->return_options & SEARCH_RETURN_PARTIAL) != 0 &&
+	    (ctx->return_options & SEARCH_RETURN_ALL) != 0) {
+		client_send_command_error(cmd, "PARTIAL conflicts with ALL");
+		return FALSE;
+	}
+
+	if (ctx->return_options == 0)
+		ctx->return_options = SEARCH_RETURN_ALL;
+	ctx->return_options |= SEARCH_RETURN_ESEARCH;
+	return TRUE;
+}
+
+static void imap_search_args_check(struct imap_search_context *ctx,
+				   const struct mail_search_arg *sargs)
+{
+	for (; sargs != NULL; sargs = sargs->next) {
+		switch (sargs->type) {
+		case SEARCH_SEQSET:
+			ctx->have_seqsets = TRUE;
+			break;
+		case SEARCH_MODSEQ:
+			ctx->have_modseqs = TRUE;
+			break;
+		case SEARCH_OR:
+		case SEARCH_SUB:
+			imap_search_args_check(ctx, sargs->value.subargs);
+			break;
+		default:
+			break;
+		}
+	}
+}
+
+static void imap_search_result_save(struct imap_search_context *ctx)
+{
+	struct client *client = ctx->cmd->client;
+	struct mail_search_result *result;
+	struct imap_search_update *update;
+
+	if (!array_is_created(&client->search_updates))
+		i_array_init(&client->search_updates, 32);
+	else if (array_count(&client->search_updates) >=
+		 CLIENT_MAX_SEARCH_UPDATES) {
+		/* too many updates */
+		string_t *str = t_str_new(256);
+		str_append(str, "* NO [NOUPDATE ");
+		imap_append_quoted(str, ctx->cmd->tag);
+		str_append_c(str, ']');
+		client_send_line(client, str_c(str));
+		ctx->return_options &= ENUM_NEGATE(SEARCH_RETURN_UPDATE);
+		imap_search_context_free(ctx);
+		return;
+	}
+	result = mailbox_search_result_save(ctx->search_ctx,
+					MAILBOX_SEARCH_RESULT_FLAG_UPDATE |
+					MAILBOX_SEARCH_RESULT_FLAG_QUEUE_SYNC);
+
+	update = array_append_space(&client->search_updates);
+	update->tag = i_strdup(ctx->cmd->tag);
+	update->result = result;
+	update->return_uids = ctx->cmd->uid;
+	update->fetch_pool = ctx->fetch_pool;
+	update->fetch_ctx = ctx->fetch_ctx;
+	ctx->fetch_pool = NULL;
+	ctx->fetch_ctx = NULL;
+}
+
+static void imap_search_send_result_standard(struct imap_search_context *ctx)
+{
+	const struct seq_range *range;
+	string_t *str;
+	uint32_t seq;
+
+	str = t_str_new(1024);
+	str_append(str, ctx->sorting ? "* SORT" : "* SEARCH");
+	array_foreach(&ctx->result, range) {
+		for (seq = range->seq1; seq <= range->seq2; seq++)
+			str_printfa(str, " %u", seq);
+		if (str_len(str) >= 1024-32) {
+			o_stream_nsend(ctx->cmd->client->output,
+				       str_data(str), str_len(str));
+			str_truncate(str, 0);
+		}
+	}
+
+	if (ctx->highest_seen_modseq != 0) {
+		str_printfa(str, " (MODSEQ %"PRIu64")",
+			    ctx->highest_seen_modseq);
+	}
+	str_append(str, "\r\n");
+	o_stream_nsend(ctx->cmd->client->output, str_data(str), str_len(str));
+}
+
+static void
+imap_search_send_partial(struct imap_search_context *ctx, string_t *str)
+{
+	str_printfa(str, " PARTIAL (%u:%u ", ctx->partial1, ctx->partial2);
+	if (array_count(&ctx->result) == 0) {
+		/* no results (in range) */
+		str_append(str, "NIL");
+	} else {
+		imap_write_seq_range(str, &ctx->result);
+	}
+	str_append_c(str, ')');
+}
+
+static void
+imap_search_send_relevancy(struct imap_search_context *ctx, string_t *dest)
+{
+	const float *scores;
+	unsigned int i, count;
+	float diff, imap_score;
+
+	scores = array_get(&ctx->relevancy_scores, &count);
+	if (count == 0)
+		return;
+
+	/* we'll need to convert float scores to numbers 1..100
+	   FIXME: would be a good idea to try to detect non-linear score
+	   mappings and convert them better.. */
+	diff = ctx->max_relevancy - ctx->min_relevancy;
+	if (diff == 0)
+		diff = 1.0;
+	for (i = 0; i < count; i++) {
+		if (i > 0)
+			str_append_c(dest, ' ');
+		imap_score = (scores[i] - ctx->min_relevancy) / diff * 100.0;
+		if (imap_score < 1)
+			str_append(dest, "1");
+		else
+			str_printfa(dest, "%u", (unsigned int)imap_score);
+	}
+}
+
+static void imap_search_send_result(struct imap_search_context *ctx)
+{
+	struct client *client = ctx->cmd->client;
+	string_t *str;
+
+	if ((ctx->return_options & SEARCH_RETURN_ESEARCH) == 0) {
+		imap_search_send_result_standard(ctx);
+		return;
+	}
+
+	if (ctx->return_options ==
+	    (SEARCH_RETURN_ESEARCH | SEARCH_RETURN_SAVE)) {
+		/* we only wanted to save the result, don't return
+		   ESEARCH result. */
+		return;
+	}
+
+	str = str_new(default_pool, 1024);
+	str_append(str, "* ESEARCH (TAG ");
+	imap_append_string(str, ctx->cmd->tag);
+	str_append_c(str, ')');
+
+	if (ctx->cmd->uid)
+		str_append(str, " UID");
+
+	if ((ctx->return_options & SEARCH_RETURN_MIN) != 0 && ctx->min_id != 0)
+		str_printfa(str, " MIN %u", ctx->min_id);
+	if ((ctx->return_options & SEARCH_RETURN_MAX) != 0 &&
+	    ctx->max_seq != 0) {
+		uint32_t id = ctx->cmd->uid ? ctx->max_uid : ctx->max_seq;
+		str_printfa(str, " MAX %u", id);
+	}
+
+	if ((ctx->return_options & SEARCH_RETURN_ALL) != 0 &&
+	    array_count(&ctx->result) > 0) {
+		str_append(str, " ALL ");
+		imap_write_seq_range(str, &ctx->result);
+	}
+	if ((ctx->return_options & SEARCH_RETURN_RELEVANCY) != 0) {
+		str_append(str, " RELEVANCY (");
+		imap_search_send_relevancy(ctx, str);
+		str_append_c(str, ')');
+	}
+
+	if ((ctx->return_options & SEARCH_RETURN_PARTIAL) != 0)
+		imap_search_send_partial(ctx, str);
+
+	if ((ctx->return_options & SEARCH_RETURN_COUNT) != 0)
+		str_printfa(str, " COUNT %u", ctx->result_count);
+	if (ctx->highest_seen_modseq != 0) {
+		str_printfa(str, " MODSEQ %"PRIu64,
+			    ctx->highest_seen_modseq);
+	}
+	str_append(str, "\r\n");
+	o_stream_nsend(client->output, str_data(str), str_len(str));
+	str_free(&str);
+}
+
+static void
+search_update_mail(struct imap_search_context *ctx, struct mail *mail)
+{
+	uint64_t modseq;
+
+	if (ctx->max_update_seq == mail->seq) {
+		/* MIN already handled this mail */
+		return;
+	}
+	ctx->max_update_seq = mail->seq;
+
+	if ((ctx->return_options & SEARCH_RETURN_MODSEQ) != 0) {
+		modseq = mail_get_modseq(mail);
+		if (ctx->highest_seen_modseq < modseq)
+			ctx->highest_seen_modseq = modseq;
+	}
+	if ((ctx->return_options & SEARCH_RETURN_SAVE) != 0) {
+		seq_range_array_add(&ctx->cmd->client->search_saved_uidset,
+				    mail->uid);
+	}
+	if ((ctx->return_options & SEARCH_RETURN_RELEVANCY) != 0) {
+		const char *str;
+		float score;
+
+		if (mail_get_special(mail, MAIL_FETCH_SEARCH_RELEVANCY, &str) < 0)
+			score = 0;
+		else
+			score = strtod(str, NULL);
+		array_push_back(&ctx->relevancy_scores, &score);
+		if (ctx->min_relevancy > score)
+			ctx->min_relevancy = score;
+		if (ctx->max_relevancy < score)
+			ctx->max_relevancy = score;
+	}
+}
+
+static void search_add_result_id(struct imap_search_context *ctx, uint32_t id)
+{
+	struct seq_range *range;
+	unsigned int count;
+
+	/* only append the data. this is especially important when we're
+	   returning a sort result. */
+	range = array_get_modifiable(&ctx->result, &count);
+	if (count > 0 && id == range[count-1].seq2 + 1) {
+		range[count-1].seq2++;
+	} else {
+		range = array_append_space(&ctx->result);
+		range->seq1 = range->seq2 = id;
+	}
+}
+
+static bool cmd_search_more(struct client_command_context *cmd)
+{
+	struct imap_search_context *ctx = cmd->context;
+	enum search_return_options opts = ctx->return_options;
+	struct mail *mail;
+	enum mailbox_sync_flags sync_flags;
+	uint32_t id;
+	const char *ok_reply;
+	bool tryagain, lost_data;
+
+	if (cmd->cancel) {
+		(void)imap_search_deinit(ctx);
+		return TRUE;
+	}
+
+	while (mailbox_search_next_nonblock(ctx->search_ctx,
+					    &mail, &tryagain)) {
+		id = cmd->uid ? mail->uid : mail->seq;
+		ctx->result_count++;
+
+		ctx->max_seq = mail->seq;
+		ctx->max_uid = mail->uid;
+		if (HAS_ANY_BITS(opts, SEARCH_RETURN_MIN) && ctx->min_id == 0) {
+			/* MIN not set yet */
+			ctx->min_id = id;
+			search_update_mail(ctx, mail);
+		}
+		if (HAS_ANY_BITS(opts, SEARCH_RETURN_ALL)) {
+			/* ALL and PARTIAL are mutually exclusive */
+			i_assert(HAS_NO_BITS(opts, SEARCH_RETURN_PARTIAL));
+			search_add_result_id(ctx, id);
+		} else if ((opts & SEARCH_RETURN_PARTIAL) != 0) {
+			/* only update if it's within range */
+			i_assert(HAS_NO_BITS(opts, SEARCH_RETURN_ALL));
+			if (ctx->partial1 <= ctx->result_count &&
+			    ctx->partial2 >= ctx->result_count)
+				search_add_result_id(ctx, id);
+			else if (HAS_ALL_BITS(opts, SEARCH_RETURN_COUNT |
+					     SEARCH_RETURN_SAVE)) {
+				/* (SAVE COUNT PARTIAL n:m) must include all
+				   results in SAVE, but not include mails
+				   outside the PARTIAL range in MODSEQ or
+				   RELEVANCY */
+				seq_range_array_add(&cmd->client->search_saved_uidset,
+						    mail->uid);
+				continue;
+			} else {
+				continue;
+			}
+		} else if (HAS_ANY_BITS(opts, SEARCH_RETURN_COUNT)) {
+			/* with COUNT don't add it to results, but handle
+			   SAVE and MODSEQ */
+		} else if (HAS_ANY_BITS(opts, SEARCH_RETURN_MIN |
+					SEARCH_RETURN_MAX)) {
+			/* MIN and/or MAX only requested, but we don't know if
+			   this is MAX until the search is finished. */
+			continue;
+		} else if (HAS_ANY_BITS(opts, SEARCH_RETURN_SAVE)) {
+			/* Only SAVE used */
+		}
+		search_update_mail(ctx, mail);
+	}
+	if (tryagain)
+		return FALSE;
+
+	if ((opts & SEARCH_RETURN_MAX) != 0 && ctx->max_seq != 0 &&
+	    ctx->max_update_seq != ctx->max_seq &&
+	    HAS_ANY_BITS(opts, SEARCH_RETURN_MODSEQ |
+			 SEARCH_RETURN_SAVE | SEARCH_RETURN_RELEVANCY)) {
+		/* finish handling MAX */
+		mail = mail_alloc(ctx->trans, 0, NULL);
+		mail_set_seq(mail, ctx->max_seq);
+		search_update_mail(ctx, mail);
+		mail_free(&mail);
+	}
+
+	lost_data = mailbox_search_seen_lost_data(ctx->search_ctx);
+	if (imap_search_deinit(ctx) < 0) {
+		client_send_box_error(cmd, cmd->client->mailbox);
+		return TRUE;
+	}
+
+	sync_flags = MAILBOX_SYNC_FLAG_FAST;
+	if (!cmd->uid || ctx->have_seqsets)
+		sync_flags |= MAILBOX_SYNC_FLAG_NO_EXPUNGES;
+	ok_reply = t_strdup_printf("OK %s%s completed",
+		lost_data ? "["IMAP_RESP_CODE_EXPUNGEISSUED"] " : "",
+		!ctx->sorting ? "Search"  : "Sort");
+	return cmd_sync(cmd, sync_flags, 0, ok_reply);
+}
+
+static void cmd_search_more_callback(struct client_command_context *cmd)
+{
+	struct client *client = cmd->client;
+	bool finished;
+
+	o_stream_cork(client->output);
+	finished = command_exec(cmd);
+	o_stream_uncork(client->output);
+
+	if (!finished)
+		(void)client_handle_unfinished_cmd(cmd);
+	else
+		client_command_free(&cmd);
+	cmd_sync_delayed(client);
+
+	client_continue_pending_input(client);
+}
+
+int cmd_search_parse_return_if_found(struct imap_search_context *ctx,
+				     const struct imap_arg **_args)
+{
+	const struct imap_arg *list_args, *args = *_args;
+	struct client_command_context *cmd = ctx->cmd;
+
+	if (!imap_arg_atom_equals(&args[0], "RETURN") ||
+	    !imap_arg_get_list(&args[1], &list_args)) {
+		ctx->return_options = SEARCH_RETURN_ALL;
+		return 1;
+	}
+
+	if (!search_parse_return_options(ctx, list_args)) {
+		imap_search_context_free(ctx);
+		return -1;
+	}
+
+	if ((ctx->return_options & SEARCH_RETURN_SAVE) != 0) {
+		/* wait if there is another SEARCH SAVE command running. */
+		if (client_handle_search_save_ambiguity(cmd)) {
+			imap_search_context_free(ctx);
+			return 0;
+		}
+
+		cmd->search_save_result = TRUE;
+	}
+
+	*_args = args + 2;
+	return 1;
+}
+
+bool imap_search_start(struct imap_search_context *ctx,
+		       struct mail_search_args *sargs,
+		       const enum mail_sort_type *sort_program)
+{
+	struct client_command_context *cmd = ctx->cmd;
+
+	imap_search_args_check(ctx, sargs->args);
+
+	if (ctx->have_modseqs) {
+		ctx->return_options |= SEARCH_RETURN_MODSEQ;
+		client_enable(cmd->client, imap_feature_condstore);
+	}
+
+	ctx->box = cmd->client->mailbox;
+	ctx->trans = mailbox_transaction_begin(ctx->box, 0,
+					       imap_client_command_get_reason(cmd));
+	ctx->sargs = sargs;
+	ctx->search_ctx =
+		mailbox_search_init(ctx->trans, sargs, sort_program, 0, NULL);
+	ctx->sorting = sort_program != NULL;
+	i_array_init(&ctx->result, 128);
+	if ((ctx->return_options & SEARCH_RETURN_UPDATE) != 0)
+		imap_search_result_save(ctx);
+	else {
+		i_assert(ctx->fetch_ctx == NULL);
+	}
+	if ((ctx->return_options & SEARCH_RETURN_RELEVANCY) != 0)
+		i_array_init(&ctx->relevancy_scores, 128);
+
+	cmd->func = cmd_search_more;
+	cmd->context = ctx;
+
+	if (cmd_search_more(cmd))
+		return TRUE;
+
+	/* we may have moved onto syncing by now */
+	if (cmd->func == cmd_search_more) {
+		ctx->to = timeout_add(0, cmd_search_more_callback, cmd);
+		cmd->state = CLIENT_COMMAND_STATE_WAIT_EXTERNAL;
+	}
+	return FALSE;
+}
+
+static int imap_search_deinit(struct imap_search_context *ctx)
+{
+	int ret = 0;
+
+	if (mailbox_search_deinit(&ctx->search_ctx) < 0)
+		ret = -1;
+
+	/* Send the result also after failing. It might have something useful,
+	   even though it didn't fully succeed. The client should be able to
+	   realize that there was some failure because NO is returned. */
+	if (!ctx->cmd->cancel &&
+	    (ret == 0 || array_count(&ctx->result) > 0))
+		imap_search_send_result(ctx);
+
+	if (ret < 0 || ctx->cmd->cancel) {
+		/* search failed */
+		if ((ctx->return_options & SEARCH_RETURN_SAVE) != 0)
+			array_clear(&ctx->cmd->client->search_saved_uidset);
+	}
+
+	(void)mailbox_transaction_commit(&ctx->trans);
+
+	timeout_remove(&ctx->to);
+	if (array_is_created(&ctx->relevancy_scores))
+		array_free(&ctx->relevancy_scores);
+	array_free(&ctx->result);
+	mail_search_args_deinit(ctx->sargs);
+	mail_search_args_unref(&ctx->sargs);
+	imap_search_context_free(ctx);
+
+	ctx->cmd->context = NULL;
+	return ret;
+}
+
+void imap_search_context_free(struct imap_search_context *ctx)
+{
+	if (ctx->fetch_ctx != NULL) {
+		imap_fetch_free(&ctx->fetch_ctx);
+		pool_unref(&ctx->fetch_pool);
+	}
+}
+
+void imap_search_update_free(struct imap_search_update *update)
+{
+	if (update->fetch_ctx != NULL) {
+		imap_fetch_free(&update->fetch_ctx);
+		pool_unref(&update->fetch_pool);
+	}
+	mailbox_search_result_free(&update->result);
+	i_free(update->tag);
+}
diff --git a/src/imap/imap-search.h b/src/imap/imap-search.h
new file mode 100644
index 0000000..f665375
--- /dev/null
+++ b/src/imap/imap-search.h
@@ -0,0 +1,61 @@
+#ifndef IMAP_SEARCH_H
+#define IMAP_SEARCH_H
+
+#include <sys/time.h>
+
+enum search_return_options {
+	SEARCH_RETURN_ESEARCH		= 0x0001,
+	SEARCH_RETURN_MIN		= 0x0002,
+	SEARCH_RETURN_MAX		= 0x0004,
+	SEARCH_RETURN_ALL		= 0x0008,
+	SEARCH_RETURN_COUNT		= 0x0010,
+	SEARCH_RETURN_MODSEQ		= 0x0020,
+	SEARCH_RETURN_SAVE		= 0x0040,
+	SEARCH_RETURN_UPDATE		= 0x0080,
+	SEARCH_RETURN_PARTIAL		= 0x0100,
+	SEARCH_RETURN_RELEVANCY		= 0x0200
+/* Options that don't return any seq/uid results, and also don't affect
+   SEARCHRES $ when combined with MIN/MAX. */
+#define SEARCH_RETURN_NORESULTS \
+	(SEARCH_RETURN_ESEARCH | SEARCH_RETURN_MODSEQ | SEARCH_RETURN_SAVE | \
+	 SEARCH_RETURN_UPDATE | SEARCH_RETURN_RELEVANCY)
+};
+
+struct imap_search_context {
+	struct client_command_context *cmd;
+	struct mailbox *box;
+	struct mailbox_transaction_context *trans;
+        struct mail_search_context *search_ctx;
+
+	pool_t fetch_pool;
+	struct imap_fetch_context *fetch_ctx;
+
+	struct mail_search_args *sargs;
+	enum search_return_options return_options;
+	uint32_t partial1, partial2;
+
+	struct timeout *to;
+	ARRAY_TYPE(seq_range) result;
+	unsigned int result_count;
+	uint32_t min_id, max_update_seq, max_seq, max_uid;
+
+	ARRAY(float) relevancy_scores;
+	float min_relevancy, max_relevancy;
+
+	uint64_t highest_seen_modseq;
+
+	bool have_seqsets:1;
+	bool have_modseqs:1;
+	bool sorting:1;
+};
+
+int cmd_search_parse_return_if_found(struct imap_search_context *ctx,
+				     const struct imap_arg **args);
+void imap_search_context_free(struct imap_search_context *ctx);
+
+bool imap_search_start(struct imap_search_context *ctx,
+		       struct mail_search_args *sargs,
+		       const enum mail_sort_type *sort_program) ATTR_NULL(3);
+void imap_search_update_free(struct imap_search_update *update);
+
+#endif
diff --git a/src/imap/imap-settings.c b/src/imap/imap-settings.c
new file mode 100644
index 0000000..2acf9dd
--- /dev/null
+++ b/src/imap/imap-settings.c
@@ -0,0 +1,197 @@
+/* Copyright (c) 2005-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "buffer.h"
+#include "hostpid.h"
+#include "settings-parser.h"
+#include "service-settings.h"
+#include "mail-storage-settings.h"
+#include "smtp-submit-settings.h"
+#include "imap-settings.h"
+
+#include <stddef.h>
+#include <unistd.h>
+
+static bool imap_settings_verify(void *_set, pool_t pool,
+				 const char **error_r);
+
+/* <settings checks> */
+static struct file_listener_settings imap_unix_listeners_array[] = {
+	{ "login/imap", 0666, "", "" },
+	{ "imap-master", 0600, "", "" }
+};
+static struct file_listener_settings *imap_unix_listeners[] = {
+	&imap_unix_listeners_array[0],
+	&imap_unix_listeners_array[1]
+};
+static buffer_t imap_unix_listeners_buf = {
+	{ { imap_unix_listeners, sizeof(imap_unix_listeners) } }
+};
+/* </settings checks> */
+
+struct service_settings imap_service_settings = {
+	.name = "imap",
+	.protocol = "imap",
+	.type = "",
+	.executable = "imap",
+	.user = "",
+	.group = "",
+	.privileged_group = "",
+	.extra_groups = "$default_internal_group",
+	.chroot = "",
+
+	.drop_priv_before_exec = FALSE,
+
+	.process_min_avail = 0,
+	.process_limit = 1024,
+	.client_limit = 1,
+	.service_count = 1,
+	.idle_kill = 0,
+	.vsz_limit = UOFF_T_MAX,
+
+	.unix_listeners = { { &imap_unix_listeners_buf,
+			      sizeof(imap_unix_listeners[0]) } },
+	.fifo_listeners = ARRAY_INIT,
+	.inet_listeners = ARRAY_INIT
+};
+
+#undef DEF
+#undef DEFLIST
+#define DEF(type, name) \
+	SETTING_DEFINE_STRUCT_##type(#name, name, struct imap_settings)
+#define DEFLIST(field, name, defines) \
+	{ .type = SET_DEFLIST, .key = name, \
+	  .offset = offsetof(struct imap_settings, field), \
+	  .list_info = defines }
+
+static const struct setting_define imap_setting_defines[] = {
+	DEF(BOOL, verbose_proctitle),
+	DEF(STR_VARS, rawlog_dir),
+
+	DEF(SIZE, imap_max_line_length),
+	DEF(TIME, imap_idle_notify_interval),
+	DEF(STR, imap_capability),
+	DEF(STR, imap_client_workarounds),
+	DEF(STR, imap_logout_format),
+	DEF(STR, imap_id_send),
+	DEF(STR, imap_id_log),
+	DEF(ENUM, imap_fetch_failure),
+	DEF(BOOL, imap_metadata),
+	DEF(BOOL, imap_literal_minus),
+	DEF(TIME, imap_hibernate_timeout),
+
+	DEF(STR, imap_urlauth_host),
+	DEF(IN_PORT, imap_urlauth_port),
+
+	SETTING_DEFINE_LIST_END
+};
+
+static const struct imap_settings imap_default_settings = {
+	.verbose_proctitle = FALSE,
+	.rawlog_dir = "",
+
+	/* RFC-2683 recommends at least 8000 bytes. Some clients however don't
+	   break large message sets to multiple commands, so we're pretty
+	   liberal by default. */
+	.imap_max_line_length = 64*1024,
+	.imap_idle_notify_interval = 2*60,
+	.imap_capability = "",
+	.imap_client_workarounds = "",
+	.imap_logout_format = "in=%i out=%o deleted=%{deleted} "
+		"expunged=%{expunged} trashed=%{trashed} "
+		"hdr_count=%{fetch_hdr_count} hdr_bytes=%{fetch_hdr_bytes} "
+		"body_count=%{fetch_body_count} body_bytes=%{fetch_body_bytes}",
+	.imap_id_send = "name *",
+	.imap_id_log = "",
+	.imap_fetch_failure = "disconnect-immediately:disconnect-after:no-after",
+	.imap_metadata = FALSE,
+	.imap_literal_minus = FALSE,
+	.imap_hibernate_timeout = 0,
+
+	.imap_urlauth_host = "",
+	.imap_urlauth_port = 143
+};
+
+static const struct setting_parser_info *imap_setting_dependencies[] = {
+	&mail_user_setting_parser_info,
+	&smtp_submit_setting_parser_info,
+	NULL
+};
+
+const struct setting_parser_info imap_setting_parser_info = {
+	.module_name = "imap",
+	.defines = imap_setting_defines,
+	.defaults = &imap_default_settings,
+
+	.type_offset = SIZE_MAX,
+	.struct_size = sizeof(struct imap_settings),
+
+	.parent_offset = SIZE_MAX,
+
+	.check_func = imap_settings_verify,
+	.dependencies = imap_setting_dependencies
+};
+
+/* <settings checks> */
+struct imap_client_workaround_list {
+	const char *name;
+	enum imap_client_workarounds num;
+};
+
+static const struct imap_client_workaround_list imap_client_workaround_list[] = {
+	{ "delay-newmail", WORKAROUND_DELAY_NEWMAIL },
+	{ "tb-extra-mailbox-sep", WORKAROUND_TB_EXTRA_MAILBOX_SEP },
+	{ "tb-lsub-flags", WORKAROUND_TB_LSUB_FLAGS },
+	{ NULL, 0 }
+};
+
+static int
+imap_settings_parse_workarounds(struct imap_settings *set,
+				const char **error_r)
+{
+        enum imap_client_workarounds client_workarounds = 0;
+        const struct imap_client_workaround_list *list;
+	const char *const *str;
+
+        str = t_strsplit_spaces(set->imap_client_workarounds, " ,");
+	for (; *str != NULL; str++) {
+		list = imap_client_workaround_list;
+		for (; list->name != NULL; list++) {
+			if (strcasecmp(*str, list->name) == 0) {
+				client_workarounds |= list->num;
+				break;
+			}
+		}
+		if (list->name == NULL) {
+			*error_r = t_strdup_printf("imap_client_workarounds: "
+				"Unknown workaround: %s", *str);
+			return -1;
+		}
+	}
+	set->parsed_workarounds = client_workarounds;
+	return 0;
+}
+
+
+static bool
+imap_settings_verify(void *_set, pool_t pool ATTR_UNUSED, const char **error_r)
+{
+	struct imap_settings *set = _set;
+
+	if (imap_settings_parse_workarounds(set, error_r) < 0)
+		return FALSE;
+
+	if (strcmp(set->imap_fetch_failure, "disconnect-immediately") == 0)
+		set->parsed_fetch_failure = IMAP_CLIENT_FETCH_FAILURE_DISCONNECT_IMMEDIATELY;
+	else if (strcmp(set->imap_fetch_failure, "disconnect-after") == 0)
+		set->parsed_fetch_failure = IMAP_CLIENT_FETCH_FAILURE_DISCONNECT_AFTER;
+	else if (strcmp(set->imap_fetch_failure, "no-after") == 0)
+		set->parsed_fetch_failure = IMAP_CLIENT_FETCH_FAILURE_NO_AFTER;
+	else {
+		*error_r = t_strdup_printf("Unknown imap_fetch_failure: %s",
+					   set->imap_fetch_failure);
+		return FALSE;
+	}
+	return TRUE;
+}
+/* </settings checks> */
diff --git a/src/imap/imap-settings.h b/src/imap/imap-settings.h
new file mode 100644
index 0000000..f4ff7bc
--- /dev/null
+++ b/src/imap/imap-settings.h
@@ -0,0 +1,49 @@
+#ifndef IMAP_SETTINGS_H
+#define IMAP_SETTINGS_H
+
+#include "net.h"
+
+struct mail_user_settings;
+
+/* <settings checks> */
+enum imap_client_workarounds {
+	WORKAROUND_DELAY_NEWMAIL		= 0x01,
+	WORKAROUND_TB_EXTRA_MAILBOX_SEP		= 0x08,
+	WORKAROUND_TB_LSUB_FLAGS		= 0x10
+};
+
+enum imap_client_fetch_failure {
+	IMAP_CLIENT_FETCH_FAILURE_DISCONNECT_IMMEDIATELY,
+	IMAP_CLIENT_FETCH_FAILURE_DISCONNECT_AFTER,
+	IMAP_CLIENT_FETCH_FAILURE_NO_AFTER,
+};
+/* </settings checks> */
+
+struct imap_settings {
+	bool verbose_proctitle;
+	const char *rawlog_dir;
+
+	/* imap: */
+	uoff_t imap_max_line_length;
+	unsigned int imap_idle_notify_interval;
+	const char *imap_capability;
+	const char *imap_client_workarounds;
+	const char *imap_logout_format;
+	const char *imap_id_send;
+	const char *imap_id_log;
+	const char *imap_fetch_failure;
+	bool imap_metadata;
+	bool imap_literal_minus;
+	unsigned int imap_hibernate_timeout;
+
+	/* imap urlauth: */
+	const char *imap_urlauth_host;
+	in_port_t imap_urlauth_port;
+
+	enum imap_client_workarounds parsed_workarounds;
+	enum imap_client_fetch_failure parsed_fetch_failure;
+};
+
+extern const struct setting_parser_info imap_setting_parser_info;
+
+#endif
diff --git a/src/imap/imap-state.c b/src/imap/imap-state.c
new file mode 100644
index 0000000..2b064ec
--- /dev/null
+++ b/src/imap/imap-state.c
@@ -0,0 +1,897 @@
+/* Copyright (c) 2014-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "crc32.h"
+#include "numpack.h"
+#include "net.h"
+#include "ostream.h"
+#include "str.h"
+#include "str-sanitize.h"
+#include "imap-util.h"
+#include "mail-search-build.h"
+#include "mail-storage-private.h"
+#include "mailbox-recent-flags.h"
+#include "imap-client.h"
+#include "imap-feature.h"
+#include "imap-fetch.h"
+#include "imap-search-args.h"
+#include "imap-state.h"
+
+enum imap_state_type_public {
+	IMAP_STATE_TYPE_MAILBOX			= 'B',
+	IMAP_STATE_TYPE_ENABLED_FEATURE		= 'F',
+	IMAP_STATE_TYPE_SEARCHRES		= '1',
+};
+
+enum imap_state_type_internal {
+	IMAP_STATE_TYPE_ID_LOGGED		= 'I',
+	IMAP_STATE_TYPE_TLS_COMPRESSION		= 'C',
+};
+
+struct mailbox_import_state {
+	const char *vname;
+	guid_128_t mailbox_guid;
+	bool examined;
+	uint32_t keywords_count, keywords_crc32, uids_crc32;
+	uint32_t uidvalidity, uidnext, messages;
+	uint64_t highest_modseq;
+	ARRAY_TYPE(seq_range) recent_uids;
+};
+
+static void
+export_seq_range(buffer_t *dest, const ARRAY_TYPE(seq_range) *range)
+{
+	const struct seq_range *uids;
+	unsigned int i, count;
+	uint32_t next_uid;
+
+	uids = array_get(range, &count);
+	numpack_encode(dest, count);
+	next_uid = 1;
+	for (i = 0; i < count; i++) {
+		i_assert(uids[i].seq1 >= next_uid);
+		if (uids[i].seq1 == uids[i].seq2) {
+			numpack_encode(dest, (uids[i].seq1 - next_uid) << 1);
+		} else {
+			numpack_encode(dest, 1 | ((uids[i].seq1 - next_uid) << 1));
+			numpack_encode(dest, uids[i].seq2 - uids[i].seq1 - 1);
+		}
+		next_uid = uids[i].seq2 + 1;
+	}
+}
+
+static int
+import_seq_range(const unsigned char **data, const unsigned char *end,
+		 ARRAY_TYPE(seq_range) *range)
+{
+	uint32_t i, count, next_uid, num, uid1, uid2;
+
+	if (numpack_decode32(data, end, &count) < 0)
+		return -1;
+	next_uid = 1;
+
+	for (i = 0; i < count; i++) {
+		if (numpack_decode32(data, end, &num) < 0)
+			return -1;
+		uid1 = next_uid + (num >> 1);
+		if ((num & 1) == 0) {
+			uid2 = uid1;
+			seq_range_array_add(range, uid1);
+		} else {
+			if (numpack_decode32(data, end, &num) < 0)
+				return -1;
+			uid2 = uid1 + num + 1;
+			seq_range_array_add_range(range, uid1, uid2);
+		}
+		next_uid = uid2 + 1;
+	}
+	return 0;
+}
+
+int imap_state_export_internal(struct client *client, buffer_t *dest,
+			       const char **error_r)
+{
+	/* the only IMAP command we allow running is IDLE or X-STATE */
+	if (client->command_queue_size > 1) {
+		*error_r = "Multiple commands in progress";
+		return 0;
+	}
+	if (client->command_queue == NULL ||
+	    strcasecmp(client->command_queue->name, "IDLE") != 0) {
+		/* this would require saving the seq <-> uid mapping
+		   and restore it on import. quite a lot of trouble if
+		   messages have been expunged in the mean time. */
+		*error_r = "Non-IDLE connections not supported currently";
+		return 0;
+	}
+	return client->v.state_export(client, TRUE, dest, error_r);
+}
+
+int imap_state_export_external(struct client *client, buffer_t *dest,
+			       const char **error_r)
+{
+	if (client->command_queue_size > 1) {
+		*error_r = "Multiple commands in progress";
+		return 0;
+	}
+
+	i_assert(client->command_queue_size == 1);
+	i_assert(strcmp(client->command_queue->name, "X-STATE") == 0);
+	return client->v.state_export(client, FALSE, dest, error_r);
+}
+
+static int
+imap_state_import(struct client *client, bool internal,
+		  const unsigned char *data, size_t size, const char **error_r)
+{
+	ssize_t ret;
+
+	while (size > 0) {
+		ret = client->v.state_import(client, internal,
+					     data, size, error_r);
+		if (ret <= 0) {
+			i_assert(*error_r != NULL);
+			return ret < 0 ? -1 : 0;
+		}
+		i_assert((size_t)ret <= size);
+		data += ret;
+		size -= ret;
+	}
+	return 1;
+}
+
+int imap_state_import_internal(struct client *client,
+			       const unsigned char *data, size_t size,
+			       const char **error_r)
+{
+	return imap_state_import(client, TRUE, data, size, error_r);
+}
+
+int imap_state_import_external(struct client *client,
+			       const unsigned char *data, size_t size,
+			       const char **error_r)
+{
+	return imap_state_import(client, FALSE, data, size, error_r);
+}
+
+static int
+imap_state_export_mailbox_mails(buffer_t *dest, struct mailbox *box,
+				const char **error_r)
+{
+	struct mailbox_transaction_context *trans;
+	struct mail_search_args *search_args;
+	struct mail_search_context *search_ctx;
+	struct mail *mail;
+	ARRAY_TYPE(seq_range) recent_uids;
+	uint32_t crc = 0;
+	int ret = 1;
+
+	search_args = mail_search_build_init();
+	mail_search_build_add_all(search_args);
+
+	trans = mailbox_transaction_begin(box, 0,
+				"unhibernate imap_state_export_mailbox_mails");
+	search_ctx = mailbox_search_init(trans, search_args, NULL, 0, NULL);
+	mail_search_args_unref(&search_args);
+
+	t_array_init(&recent_uids, 8);
+	while (mailbox_search_next(search_ctx, &mail)) {
+		crc = crc32_data_more(crc, &mail->uid, sizeof(mail->uid));
+		if ((mail_get_flags(mail) & MAIL_RECENT) != 0)
+			seq_range_array_add(&recent_uids, mail->uid);
+	}
+	if (mailbox_search_deinit(&search_ctx) < 0) {
+		*error_r = mailbox_get_last_internal_error(box, NULL);
+		ret = -1;
+	}
+	(void)mailbox_transaction_commit(&trans);
+
+	numpack_encode(dest, crc);
+	export_seq_range(dest, &recent_uids);
+	return ret;
+}
+
+static uint32_t
+mailbox_status_keywords_crc32(const struct mailbox_status *status)
+{
+	const char *str;
+	uint32_t crc = 0;
+
+	array_foreach_elem(status->keywords, str)
+		crc = crc32_str(str);
+	return crc;
+}
+
+static int
+imap_state_export_mailbox(buffer_t *dest, struct client *client,
+			  struct mailbox *box, const char **error_r)
+{
+        struct mailbox_status status;
+	struct mailbox_metadata metadata;
+	const char *vname = mailbox_get_vname(box);
+	enum mail_error mail_error;
+
+	mailbox_get_open_status(box, STATUS_UIDVALIDITY | STATUS_UIDNEXT |
+				STATUS_MESSAGES | STATUS_HIGHESTMODSEQ |
+				STATUS_KEYWORDS,
+				&status);
+	if (status.nonpermanent_modseqs) {
+		*error_r = "Nonpermanent modseqs";
+		return 0;
+	}
+
+	if (mailbox_get_metadata(box, MAILBOX_METADATA_GUID, &metadata) < 0) {
+		*error_r = mailbox_get_last_internal_error(box, &mail_error);
+		/* if the selected mailbox can't have a GUID, fail silently */
+		return mail_error == MAIL_ERROR_NOTPOSSIBLE ? 0 : -1;
+	}
+
+	buffer_append_c(dest, IMAP_STATE_TYPE_MAILBOX);
+	buffer_append(dest, vname, strlen(vname)+1);
+	buffer_append(dest, metadata.guid, sizeof(metadata.guid));
+
+	buffer_append_c(dest, client->mailbox_examined ? 1 : 0);
+	numpack_encode(dest, status.uidvalidity);
+	numpack_encode(dest, status.uidnext);
+	numpack_encode(dest, status.messages);
+	if (client_has_enabled(client, imap_feature_qresync) &&
+	    !client->nonpermanent_modseqs)
+		numpack_encode(dest, client->sync_last_full_modseq);
+	else
+		numpack_encode(dest, status.highest_modseq);
+
+	/* keywords count + CRC32 should be enough to figure out if it
+	   needs to be resent */
+	numpack_encode(dest, array_count(status.keywords));
+	numpack_encode(dest, mailbox_status_keywords_crc32(&status));
+
+	/* we're now basically done, but just in case there's a bug add a
+	   checksum of the currently existing UIDs and verify it when
+	   importing. this also writes the list of recent UIDs. */
+	return imap_state_export_mailbox_mails(dest, box, error_r);
+}
+
+int imap_state_export_base(struct client *client, bool internal,
+			   buffer_t *dest, const char **error_r)
+{
+	int ret;
+
+	str_append(dest, "base\n");
+	if (array_is_created(&client->search_updates) &&
+	    array_count(&client->search_updates) > 0) {
+		/* these could be tricky */
+		*error_r = "CONTEXT=SEARCH updates not supported currently";
+		return 0;
+	}
+	if (client->notify_ctx != NULL) {
+		/* FIXME: this really should be supported. also IDLE wouldn't
+		   be needed if NOTIFY allows sending EXPUNGEs to selected
+		   mailbox. */
+		*error_r = "NOTIFY not supported currently";
+		return 0;
+	}
+
+	if (client->mailbox != NULL) {
+		ret = imap_state_export_mailbox(dest, client,
+						client->mailbox, error_r);
+		if (ret <= 0)
+			return ret;
+	}
+
+	/* IMAP features */
+	const char *const *features = client_enabled_features(client);
+	if (features != NULL) {
+		for (unsigned int i = 0; features[i] != NULL; i++) {
+			buffer_append_c(dest, IMAP_STATE_TYPE_ENABLED_FEATURE);
+			buffer_append(dest, features[i], strlen(features[i])+1);
+		}
+	}
+	if (internal) {
+		if (client->id_logged)
+			buffer_append_c(dest, IMAP_STATE_TYPE_ID_LOGGED);
+		if (client->tls_compression)
+			buffer_append_c(dest, IMAP_STATE_TYPE_TLS_COMPRESSION);
+	}
+
+	/* IMAP SEARCHRES extension */
+	if (array_is_created(&client->search_saved_uidset) &&
+	    array_count(&client->search_saved_uidset) > 0) {
+		buffer_append_c(dest, IMAP_STATE_TYPE_SEARCHRES);
+		export_seq_range(dest, &client->search_saved_uidset);
+	}
+	return 1;
+}
+
+static int
+import_string(const unsigned char **data, const unsigned char *end,
+	      const char **str_r)
+{
+	const unsigned char *p;
+
+	p = memchr(*data, '\0', end - *data);
+	if (p == NULL)
+		return -1;
+	*str_r = (const void *)*data;
+	*data = p + 1;
+	return 0;
+}
+
+static int
+import_send_expunges(struct client *client,
+		     const struct mailbox_import_state *state,
+		     unsigned int *expunge_count_r,
+		     const char **error_r)
+{
+	struct mailbox_transaction_context *trans;
+	struct mail_search_args *search_args;
+	struct mail_search_context *search_ctx;
+	struct mail *mail;
+	uint32_t crc = 0, seq, expunged_uid;
+	ARRAY_TYPE(seq_range) uids_filter, expunged_uids;
+	ARRAY_TYPE(uint32_t) expunged_seqs;
+	struct seq_range_iter iter;
+	const uint32_t *seqs;
+	unsigned int i, expunge_count, n = 0;
+	string_t *str;
+	int ret = 0;
+
+	*expunge_count_r = 0;
+
+	if (state->messages == 0) {
+		/* the mailbox was empty originally - there couldn't be any
+		   pending expunges. */
+		return 0;
+	}
+	if (state->uidnext <= 1) {
+		*error_r = "Invalid UIDNEXT";
+		return -1;
+	}
+
+	/* get all the message UIDs expunged since the last known modseq */
+	t_array_init(&uids_filter, 1);
+	t_array_init(&expunged_uids, 128);
+	seq_range_array_add_range(&uids_filter, 1, state->uidnext-1);
+	if (!mailbox_get_expunged_uids(client->mailbox, state->highest_modseq,
+				       &uids_filter, &expunged_uids)) {
+		*error_r = t_strdup_printf(
+			"Couldn't get recently expunged UIDs "
+			"(uidnext=%u highest_modseq=%"PRIu64")",
+			state->uidnext, state->highest_modseq);
+		return -1;
+	}
+	seq_range_array_iter_init(&iter, &expunged_uids);
+
+	search_args = mail_search_build_init();
+	mail_search_build_add_all(search_args);
+
+	trans = mailbox_transaction_begin(client->mailbox, 0,
+					  "unhibernate import_send_expunges");
+	search_ctx = mailbox_search_init(trans, search_args, NULL, 0, NULL);
+	mail_search_args_unref(&search_args);
+
+	/* find sequence numbers for the expunged UIDs */
+	t_array_init(&expunged_seqs, array_count(&expunged_uids)+1); seq = 0;
+	while (mailbox_search_next(search_ctx, &mail)) {
+		while (seq_range_array_iter_nth(&iter, n, &expunged_uid) &&
+		       expunged_uid < mail->uid && seq < state->messages) {
+			seq++; n++;
+			array_push_back(&expunged_seqs, &seq);
+			crc = crc32_data_more(crc, &expunged_uid,
+					      sizeof(expunged_uid));
+		}
+		if (seq == state->messages)
+			break;
+		crc = crc32_data_more(crc, &mail->uid, sizeof(mail->uid));
+		if (++seq == state->messages)
+			break;
+	}
+	while (seq_range_array_iter_nth(&iter, n, &expunged_uid) &&
+	       seq < state->messages) {
+		seq++; n++;
+		array_push_back(&expunged_seqs, &seq);
+		crc = crc32_data_more(crc, &expunged_uid,
+				      sizeof(expunged_uid));
+	}
+
+	if (mailbox_search_deinit(&search_ctx) < 0) {
+		*error_r = mailbox_get_last_internal_error(client->mailbox, NULL);
+		ret = -1;
+	} else if (seq != state->messages) {
+		*error_r = t_strdup_printf("Message count mismatch after "
+					   "handling expunges (%u != %u)",
+					   seq, state->messages);
+		ret = -1;
+	}
+	(void)mailbox_transaction_commit(&trans);
+	if (ret < 0)
+		return -1;
+
+	seqs = array_get(&expunged_seqs, &expunge_count);
+	if (client->messages_count + expunge_count < state->messages) {
+		*error_r = t_strdup_printf("Message count too low after "
+					   "handling expunges (%u < %u)",
+					   client->messages_count + expunge_count,
+					   state->messages);
+		return -1;
+	}
+	if (crc != state->uids_crc32) {
+		*error_r = t_strdup_printf("Message UIDs CRC32 mismatch (%u != %u)",
+					   crc, state->uids_crc32);
+		return -1;
+	}
+
+	if (!client_has_enabled(client, imap_feature_qresync)) {
+		str = t_str_new(32);
+		for (i = expunge_count; i > 0; i--) {
+			str_truncate(str, 0);
+			str_printfa(str, "* %u EXPUNGE", seqs[i-1]);
+			client_send_line(client, str_c(str));
+		}
+	} else {
+		str = str_new(default_pool, 128);
+		str_append(str, "* VANISHED ");
+		imap_write_seq_range(str, &expunged_uids);
+		str_append(str, "\r\n");
+		o_stream_nsend(client->output, str_data(str), str_len(str));
+		str_free(&str);
+	}
+	*expunge_count_r = expunge_count;
+	return 0;
+}
+
+static int
+import_send_flag_changes(struct client *client,
+			 const struct mailbox_import_state *state,
+			 unsigned int *flag_change_count_r)
+{
+	struct imap_fetch_context *fetch_ctx;
+	struct mail_search_args *search_args;
+	ARRAY_TYPE(seq_range) old_uids;
+	pool_t pool;
+	int ret;
+
+	*flag_change_count_r = 0;
+	if (state->messages == 0)
+		return 0;
+
+	t_array_init(&old_uids, 1);
+	seq_range_array_add_range(&old_uids, 1, state->uidnext-1);
+
+	search_args = mail_search_build_init();
+	search_args->args = p_new(search_args->pool, struct mail_search_arg, 1);
+	search_args->args->type = SEARCH_UIDSET;
+	search_args->args->value.seqset = old_uids;
+	imap_search_add_changed_since(search_args, state->highest_modseq);
+
+	pool = pool_alloconly_create("imap state flag changes", 1024);
+	fetch_ctx = imap_fetch_alloc(client, pool, "unhibernate");
+	pool_unref(&pool);
+
+	imap_fetch_init_nofail_handler(fetch_ctx, imap_fetch_flags_init);
+	if (client_has_enabled(client, imap_feature_qresync)) {
+		imap_fetch_init_nofail_handler(fetch_ctx, imap_fetch_uid_init);
+		imap_fetch_init_nofail_handler(fetch_ctx, imap_fetch_modseq_init);
+	}
+
+	imap_fetch_begin(fetch_ctx, client->mailbox, search_args);
+	mail_search_args_unref(&search_args);
+
+	/* FIXME: ideally do this asynchronously.. */
+	while (imap_fetch_more_no_lock_update(fetch_ctx) == 0) ;
+
+	ret = imap_fetch_end(fetch_ctx);
+	*flag_change_count_r = fetch_ctx->fetched_mails_count;
+	imap_fetch_free(&fetch_ctx);
+	return ret;
+}
+
+static ssize_t
+import_state_mailbox_struct(const unsigned char *data, size_t size,
+			    struct mailbox_import_state *state_r,
+			    const char **error_r)
+{
+	const unsigned char *p = data, *end = data + size;
+
+	i_zero(state_r);
+	t_array_init(&state_r->recent_uids, 8);
+
+	/* vname */
+	if (import_string(&p, end, &state_r->vname) < 0) {
+		*error_r = "Mailbox state truncated at name";
+		return 0;
+	}
+
+	/* GUID */
+	if (end-p < (int)sizeof(state_r->mailbox_guid)) {
+		*error_r = "Mailbox state truncated at GUID";
+		return 0;
+	}
+	memcpy(state_r->mailbox_guid, p, sizeof(state_r->mailbox_guid));
+	p += sizeof(state_r->mailbox_guid);
+
+	if (guid_128_is_empty(state_r->mailbox_guid)) {
+		*error_r = "Empty GUID";
+		return 0;
+	}
+
+	/* EXAMINEd vs SELECTed */
+	if (p == end) {
+		*error_r = "Mailbox state truncated at examined-flag";
+		return 0;
+	}
+	state_r->examined = p[0] != 0;
+	p++;
+
+	/* mailbox state */
+	if (numpack_decode32(&p, end, &state_r->uidvalidity) < 0 ||
+	    numpack_decode32(&p, end, &state_r->uidnext) < 0 ||
+	    numpack_decode32(&p, end, &state_r->messages) < 0 ||
+	    numpack_decode(&p, end, &state_r->highest_modseq) < 0 ||
+	    numpack_decode32(&p, end, &state_r->keywords_count) < 0 ||
+	    numpack_decode32(&p, end, &state_r->keywords_crc32) < 0 ||
+	    numpack_decode32(&p, end, &state_r->uids_crc32) < 0 ||
+	    import_seq_range(&p, end, &state_r->recent_uids) < 0) {
+		*error_r = "Mailbox state truncated";
+		return 0;
+	}
+	if (state_r->uidvalidity == 0) {
+		*error_r = "Empty UIDVALIDITY";
+		return 0;
+	}
+	if (state_r->uidnext == 0) {
+		*error_r = "Empty UIDNEXT";
+		return 0;
+	}
+	return p - data;
+}
+
+static int
+import_state_mailbox_open(struct client *client,
+			  const struct mailbox_import_state *state,
+			  const char **error_r)
+{
+	struct mail_namespace *ns;
+	struct mailbox *box;
+	struct mailbox_metadata metadata;
+        struct mailbox_status status;
+	const struct seq_range *range;
+	enum mailbox_flags flags = 0;
+	unsigned int expunge_count, new_mails_count = 0, flag_change_count = 0;
+	uint32_t uid;
+	int ret = 0;
+
+	ns = mail_namespace_find(client->user->namespaces, state->vname);
+	if (ns == NULL) {
+		*error_r = "Namespace not found for mailbox";
+		return -1;
+	}
+
+	if (state->examined)
+		flags |= MAILBOX_FLAG_READONLY;
+	else
+		flags |= MAILBOX_FLAG_DROP_RECENT;
+	box = mailbox_alloc(ns->list, state->vname, flags);
+	if (mailbox_open(box) < 0) {
+		*error_r = t_strdup_printf("Couldn't open mailbox: %s",
+			mailbox_get_last_internal_error(box, NULL));
+		mailbox_free(&box);
+		return -1;
+	}
+
+	ret = mailbox_enable(box, client_enabled_mailbox_features(client));
+	if (ret < 0 || mailbox_sync(box, 0) < 0) {
+		*error_r = t_strdup_printf("Couldn't sync mailbox: %s",
+			mailbox_get_last_internal_error(box, NULL));
+		mailbox_free(&box);
+		return -1;
+	}
+	/* verify that this still looks like the same mailbox */
+	if (mailbox_get_metadata(box, MAILBOX_METADATA_GUID, &metadata) < 0) {
+		*error_r = mailbox_get_last_internal_error(box, NULL);
+		mailbox_free(&box);
+		return -1;
+	}
+	if (!guid_128_equals(metadata.guid, state->mailbox_guid)) {
+		*error_r = t_strdup_printf("Mailbox GUID has changed %s->%s",
+					   guid_128_to_string(state->mailbox_guid),
+					   guid_128_to_string(metadata.guid));
+		mailbox_free(&box);
+		return -1;
+	}
+	mailbox_get_open_status(box, STATUS_UIDVALIDITY | STATUS_UIDNEXT |
+				STATUS_HIGHESTMODSEQ | STATUS_RECENT |
+				STATUS_KEYWORDS, &status);
+	if (status.uidvalidity != state->uidvalidity) {
+		*error_r = t_strdup_printf("Mailbox UIDVALIDITY has changed %u->%u",
+					    state->uidvalidity, status.uidvalidity);
+		mailbox_free(&box);
+		return -1;
+	}
+	if (status.uidnext < state->uidnext) {
+		*error_r = t_strdup_printf("Mailbox UIDNEXT shrank %u -> %u",
+					   state->uidnext, status.uidnext);
+		mailbox_free(&box);
+		return -1;
+	}
+	if (status.highest_modseq < state->highest_modseq) {
+		*error_r = t_strdup_printf("Mailbox HIGHESTMODSEQ shrank %"PRIu64" -> %"PRIu64,
+					   state->highest_modseq,
+					   status.highest_modseq);
+		mailbox_free(&box);
+		return -1;
+	}
+
+	client->mailbox = box;
+	client->mailbox_examined = state->examined;
+	client->messages_count = status.messages;
+	client->uidvalidity = status.uidvalidity;
+	client->notify_uidnext = status.uidnext;
+
+	if (import_send_expunges(client, state, &expunge_count, error_r) < 0)
+		return -1;
+	i_assert(expunge_count <= state->messages);
+	if (state->messages - expunge_count > client->messages_count) {
+		*error_r = t_strdup_printf("Mailbox message count shrank %u -> %u",
+					   client->messages_count,
+					   state->messages - expunge_count);
+		return -1;
+	}
+
+	client_update_mailbox_flags(client, status.keywords);
+	array_foreach(&state->recent_uids, range) {
+		for (uid = range->seq1; uid <= range->seq2; uid++) {
+			uint32_t seq;
+
+			if (mail_index_lookup_seq(box->view, uid, &seq))
+				mailbox_recent_flags_set_uid_forced(box, uid);
+		}
+	}
+	client->recent_count = mailbox_recent_flags_count(box);
+
+	if (state->messages - expunge_count < client->messages_count) {
+		/* new messages arrived */
+		new_mails_count = client->messages_count -
+			(state->messages - expunge_count);
+		client_send_line(client,
+			t_strdup_printf("* %u EXISTS", client->messages_count));
+		client_send_line(client,
+			t_strdup_printf("* %u RECENT", client->recent_count));
+	}
+
+	if (array_count(status.keywords) == state->keywords_count &&
+	    mailbox_status_keywords_crc32(&status) == state->keywords_crc32) {
+		/* no changes to keywords */
+		client->keywords.announce_count = state->keywords_count;
+	} else {
+		client_send_mailbox_flags(client, TRUE);
+	}
+	if (import_send_flag_changes(client, state, &flag_change_count) < 0) {
+		*error_r = "Couldn't send flag changes";
+		return -1;
+	}
+	if (client_has_enabled(client, imap_feature_qresync) &&
+	    !client->nonpermanent_modseqs &&
+	    status.highest_modseq != state->highest_modseq) {
+		client_send_line(client, t_strdup_printf(
+			"* OK [HIGHESTMODSEQ %"PRIu64"] Highest",
+			status.highest_modseq));
+		client->sync_last_full_modseq = status.highest_modseq;
+	}
+	e_debug(client->event,
+		"Unhibernation sync: %u expunges, %u new messages, %u flag changes, %"PRIu64" modseq changes",
+		expunge_count, new_mails_count, flag_change_count,
+		status.highest_modseq - state->highest_modseq);
+	return 0;
+}
+
+static ssize_t
+import_state_mailbox(struct client *client, const unsigned char *data,
+		     size_t size, const char **error_r)
+{
+	struct mailbox_import_state state;
+	ssize_t ret;
+
+	if (client->mailbox != NULL) {
+		*error_r = "Duplicate mailbox state";
+		return 0;
+	}
+
+	ret = import_state_mailbox_struct(data, size, &state, error_r);
+	if (ret <= 0) {
+		i_assert(*error_r != NULL);
+		return ret;
+	}
+	if (import_state_mailbox_open(client, &state, error_r) < 0) {
+		*error_r = t_strdup_printf("Mailbox %s: %s", state.vname, *error_r);
+		return -1;
+	}
+	return ret;
+}
+
+static ssize_t
+import_state_enabled_feature(struct client *client, const unsigned char *data,
+			     size_t size, const char **error_r)
+{
+	const unsigned char *p = data, *end = data + size;
+	const char *name;
+	unsigned int feature_idx;
+
+	if (import_string(&p, end, &name) < 0) {
+		*error_r = "Mailbox state truncated at name";
+		return 0;
+	}
+	if (!imap_feature_lookup(name, &feature_idx)) {
+		*error_r = t_strdup_printf("Unknown feature '%s'", name);
+		return 0;
+	}
+	client_enable(client, feature_idx);
+	return p - data;
+}
+
+static ssize_t
+import_state_searchres(struct client *client, const unsigned char *data,
+		       size_t size, const char **error_r)
+{
+	const unsigned char *p = data;
+
+	i_array_init(&client->search_saved_uidset, 128);
+	if (import_seq_range(&p, data+size, &client->search_saved_uidset) < 0) {
+		*error_r = "Invalid SEARCHRES seq-range";
+		return 0;
+	}
+	return p - data;
+}
+
+static ssize_t
+import_state_id_logged(struct client *client,
+		       const unsigned char *data ATTR_UNUSED,
+		       size_t size ATTR_UNUSED,
+		       const char **error_r ATTR_UNUSED)
+{
+	client->id_logged = TRUE;
+	return 0;
+}
+
+static ssize_t
+import_state_tls_compression(struct client *client,
+			     const unsigned char *data ATTR_UNUSED,
+			     size_t size ATTR_UNUSED,
+			     const char **error_r ATTR_UNUSED)
+{
+	client->tls_compression = TRUE;
+	return 0;
+}
+
+void imap_state_import_idle_cmd_tag(struct client *client, const char *tag)
+{
+	if (client->state_import_idle_continue) {
+		/* IDLE command continues */
+		struct client_command_context *cmd;
+		struct command *command;
+
+		cmd = client_command_alloc(client);
+		cmd->tag = p_strdup(cmd->pool, tag);
+		cmd->name = "IDLE";
+
+		command = command_find("IDLE");
+		i_assert(command != NULL);
+		cmd->func = command->func;
+		cmd->cmd_flags = command->flags;
+		client_command_init_finished(cmd);
+
+		if (command_exec(cmd)) {
+			/* IDLE terminated because of an external change, but
+			   DONE was already buffered */
+			client_command_free(&cmd);
+			client_add_missing_io(client);
+		} else {
+			i_assert(cmd->state == CLIENT_COMMAND_STATE_WAIT_INPUT ||
+				 cmd->state == CLIENT_COMMAND_STATE_WAIT_OUTPUT);
+		}
+	} else {
+		/* we're finishing IDLE command */
+		client_send_line(client, t_strdup_printf(
+			"%s %s Idle completed.", tag,
+			client->state_import_bad_idle_done ? "BAD" : "OK"));
+	}
+}
+
+static struct {
+	enum imap_state_type_public type;
+	ssize_t (*import)(struct client *client, const unsigned char *data,
+			  size_t size, const char **error_r);
+} imap_states_public[] = {
+	{ IMAP_STATE_TYPE_MAILBOX, import_state_mailbox },
+	{ IMAP_STATE_TYPE_ENABLED_FEATURE, import_state_enabled_feature },
+	{ IMAP_STATE_TYPE_SEARCHRES, import_state_searchres }
+};
+
+static struct {
+	enum imap_state_type_internal type;
+	ssize_t (*import)(struct client *client, const unsigned char *data,
+			  size_t size, const char **error_r);
+} imap_states_internal[] = {
+	{ IMAP_STATE_TYPE_ID_LOGGED, import_state_id_logged },
+	{ IMAP_STATE_TYPE_TLS_COMPRESSION, import_state_tls_compression }
+};
+
+static ssize_t
+imap_state_try_import_public(struct client *client, const unsigned char *data,
+			     size_t size, const char **error_r)
+{
+	unsigned int i;
+	ssize_t ret;
+
+	i_assert(size > 0);
+
+	for (i = 0; i < N_ELEMENTS(imap_states_public); i++) {
+		if (imap_states_public[i].type == data[0]) {
+			ret = imap_states_public[i].
+				import(client, data+1, size-1, error_r);
+			return ret < 0 ? -1 : ret+1;
+		}
+	}
+	return -2;
+}
+
+static ssize_t
+imap_state_try_import_internal(struct client *client, const unsigned char *data,
+			       size_t size, const char **error_r)
+{
+	unsigned int i;
+	ssize_t ret;
+
+	i_assert(size > 0);
+
+	for (i = 0; i < N_ELEMENTS(imap_states_internal); i++) {
+		if (imap_states_internal[i].type == data[0]) {
+			ret = imap_states_internal[i].
+				import(client, data+1, size-1, error_r);
+			return ret < 0 ? -1 : ret+1;
+		}
+	}
+	return -2;
+}
+
+ssize_t imap_state_import_base(struct client *client, bool internal,
+			       const unsigned char *data, size_t size,
+			       const char **error_r)
+{
+	const unsigned char *p;
+	ssize_t ret;
+	size_t pos;
+
+	i_assert(client->mailbox == NULL);
+
+	*error_r = NULL;
+
+	if (size < 5 || memcmp(data, "base\n", 5) != 0) {
+		p = memchr(data, '\n', size);
+		if (p == NULL)
+			p = data + I_MIN(size, 20);
+		*error_r = t_strdup_printf("Unknown state block '%s'",
+					   str_sanitize(t_strdup_until(data, p), 20));
+		return 0;
+	}
+
+	pos = 5;
+	while (pos < size) {
+		ret = imap_state_try_import_public(client, data+pos,
+						   size-pos, error_r);
+		if (ret == -2 && internal) {
+			ret = imap_state_try_import_internal(client, data+pos,
+							     size-pos, error_r);
+		}
+		if (ret < 0 || *error_r != NULL) {
+			if (ret == -2) {
+				*error_r = t_strdup_printf("Unknown type '%c'",
+							   data[pos]);
+			}
+			i_assert(*error_r != NULL);
+			return ret < 0 ? -1 : 0;
+		}
+		i_assert(size - pos >= (size_t)ret);
+		pos += ret;
+	}
+	return pos;
+}
diff --git a/src/imap/imap-state.h b/src/imap/imap-state.h
new file mode 100644
index 0000000..ee00376
--- /dev/null
+++ b/src/imap/imap-state.h
@@ -0,0 +1,30 @@
+#ifndef IMAP_STATE_H
+#define IMAP_STATE_H
+
+/* Export the IMAP client state to the given buffer. Returns 1 if ok,
+   0 if state couldn't be exported, -1 if temporary internal error error. */
+int imap_state_export_internal(struct client *client, buffer_t *dest,
+			       const char **error_r);
+int imap_state_export_external(struct client *client, buffer_t *dest,
+			       const char **error_r);
+
+/* Returns 1 if ok, 0 if state was corrupted, -1 if other error. Internal state
+   comes from another Dovecot component, which can override IP addresses,
+   session IDs, etc. */
+int imap_state_import_internal(struct client *client,
+			       const unsigned char *data, size_t size,
+			       const char **error_r);
+int imap_state_import_external(struct client *client,
+			       const unsigned char *data, size_t size,
+			       const char **error_r);
+
+/* INTERNAL API: Note that the "internal" flag specifies whether we're doing
+   the import/export from/to another Dovecot component or an untrusted
+   IMAP client. */
+int imap_state_export_base(struct client *client, bool internal,
+			   buffer_t *dest, const char **error_r);
+ssize_t imap_state_import_base(struct client *client, bool internal,
+			       const unsigned char *data, size_t size,
+			       const char **error_r);
+void imap_state_import_idle_cmd_tag(struct client *client, const char *tag);
+#endif
diff --git a/src/imap/imap-status.c b/src/imap/imap-status.c
new file mode 100644
index 0000000..341e537
--- /dev/null
+++ b/src/imap/imap-status.c
@@ -0,0 +1,172 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "hex-binary.h"
+#include "str.h"
+#include "imap-quote.h"
+#include "imap-status.h"
+
+int imap_status_parse_items(struct client_command_context *cmd,
+			    const struct imap_arg *args,
+			    struct imap_status_items *items_r)
+{
+	enum imap_status_item_flags flags = 0;
+	const char *item;
+
+	if (IMAP_ARG_IS_EOL(args)) {
+		client_send_command_error(cmd, "Empty status list.");
+		return -1;
+	}
+
+	i_zero(items_r);
+	for (; !IMAP_ARG_IS_EOL(args); args++) {
+		if (!imap_arg_get_atom(args, &item)) {
+			/* list may contain only atoms */
+			client_send_command_error(cmd,
+				"Status list contains non-atoms.");
+			return -1;
+		}
+
+		item = t_str_ucase(item);
+		if (strcmp(item, "MESSAGES") == 0)
+			flags |= IMAP_STATUS_ITEM_MESSAGES;
+		else if (strcmp(item, "RECENT") == 0)
+			flags |= IMAP_STATUS_ITEM_RECENT;
+		else if (strcmp(item, "UIDNEXT") == 0)
+			flags |= IMAP_STATUS_ITEM_UIDNEXT;
+		else if (strcmp(item, "UIDVALIDITY") == 0)
+			flags |= IMAP_STATUS_ITEM_UIDVALIDITY;
+		else if (strcmp(item, "UNSEEN") == 0)
+			flags |= IMAP_STATUS_ITEM_UNSEEN;
+		else if (strcmp(item, "HIGHESTMODSEQ") == 0)
+			flags |= IMAP_STATUS_ITEM_HIGHESTMODSEQ;
+		else if (strcmp(item, "SIZE") == 0)
+			flags |= IMAP_STATUS_ITEM_SIZE;
+		else if (strcmp(item, "X-SIZE") == 0)
+			flags |= IMAP_STATUS_ITEM_X_SIZE;
+		else if (strcmp(item, "X-GUID") == 0)
+			flags |= IMAP_STATUS_ITEM_X_GUID;
+		else {
+			client_send_command_error(cmd, t_strconcat(
+				"Invalid status item ", item, NULL));
+			return -1;
+		}
+	}
+
+	items_r->flags = flags;
+	return 0;
+}
+
+int imap_status_get_result(struct client *client, struct mailbox *box,
+			   const struct imap_status_items *items,
+			   struct imap_status_result *result_r)
+{
+	enum mailbox_status_items status = 0;
+	enum mailbox_metadata_items metadata = 0;
+	int ret;
+
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_MESSAGES))
+		status |= STATUS_MESSAGES;
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_RECENT))
+		status |= STATUS_RECENT;
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_UIDNEXT))
+		status |= STATUS_UIDNEXT;
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_UIDVALIDITY))
+		status |= STATUS_UIDVALIDITY;
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_UNSEEN))
+		status |= STATUS_UNSEEN;
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_HIGHESTMODSEQ)) {
+		client_enable(client, imap_feature_condstore);
+		status |= STATUS_HIGHESTMODSEQ;
+	}
+	if (HAS_ANY_BITS(items->flags, IMAP_STATUS_ITEM_SIZE |
+				       IMAP_STATUS_ITEM_X_SIZE))
+		metadata |= MAILBOX_METADATA_VIRTUAL_SIZE;
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_X_GUID))
+		metadata |= MAILBOX_METADATA_GUID;
+
+	ret = mailbox_get_status(box, status, &result_r->status);
+	if (metadata != 0 && ret == 0)
+		ret = mailbox_get_metadata(box, metadata, &result_r->metadata);
+
+	return ret;
+}
+
+int imap_status_get(struct client_command_context *cmd,
+		    struct mail_namespace *ns, const char *mailbox,
+		    const struct imap_status_items *items,
+		    struct imap_status_result *result_r)
+{
+	struct client *client = cmd->client;
+	struct mailbox *box;
+	const char *errstr;
+	int ret = 0;
+
+	if (client->mailbox != NULL &&
+	    mailbox_equals(client->mailbox, ns, mailbox)) {
+		/* this mailbox is selected */
+		box = client->mailbox;
+	} else {
+		/* open the mailbox */
+		box = mailbox_alloc(ns->list, mailbox, MAILBOX_FLAG_READONLY);
+		(void)mailbox_enable(box, client_enabled_mailbox_features(client));
+	}
+
+	ret = imap_status_get_result(client, box, items, result_r);
+	if (ret < 0) {
+		errstr = mailbox_get_last_error(box, &result_r->error);
+		result_r->errstr = imap_get_error_string(cmd, errstr,
+							 result_r->error);
+	}
+	if (box != client->mailbox)
+		mailbox_free(&box);
+	return ret;
+}
+
+int imap_status_send(struct client *client, const char *mailbox_mutf7,
+		     const struct imap_status_items *items,
+		     const struct imap_status_result *result)
+{
+	const struct mailbox_status *status = &result->status;
+	string_t *str;
+	size_t prefix_len;
+
+	str = t_str_new(128);
+	str_append(str, "* STATUS ");
+        imap_append_astring(str, mailbox_mutf7);
+	str_append(str, " (");
+
+	prefix_len = str_len(str);
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_MESSAGES))
+		str_printfa(str, "MESSAGES %u ", status->messages);
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_RECENT))
+		str_printfa(str, "RECENT %u ", status->recent);
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_UIDNEXT))
+		str_printfa(str, "UIDNEXT %u ", status->uidnext);
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_UIDVALIDITY))
+		str_printfa(str, "UIDVALIDITY %u ", status->uidvalidity);
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_UNSEEN))
+		str_printfa(str, "UNSEEN %u ", status->unseen);
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_HIGHESTMODSEQ)) {
+		str_printfa(str, "HIGHESTMODSEQ %"PRIu64" ",
+			    status->highest_modseq);
+	}
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_SIZE)) {
+		str_printfa(str, "SIZE %"PRIu64" ",
+			    result->metadata.virtual_size);
+	}
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_X_SIZE)) {
+		str_printfa(str, "X-SIZE %"PRIu64" ",
+			    result->metadata.virtual_size);
+	}
+	if (HAS_ALL_BITS(items->flags, IMAP_STATUS_ITEM_X_GUID)) {
+		str_printfa(str, "X-GUID %s ",
+			    guid_128_to_string(result->metadata.guid));
+	}
+
+	if (str_len(str) != prefix_len)
+		str_truncate(str, str_len(str)-1);
+	str_append_c(str, ')');
+
+	return client_send_line_next(client, str_c(str));
+}
diff --git a/src/imap/imap-status.h b/src/imap/imap-status.h
new file mode 100644
index 0000000..58bd581
--- /dev/null
+++ b/src/imap/imap-status.h
@@ -0,0 +1,51 @@
+#ifndef IMAP_STATUS_H
+#define IMAP_STATUS_H
+
+enum imap_status_item_flags {
+	IMAP_STATUS_ITEM_MESSAGES = BIT(0),
+	IMAP_STATUS_ITEM_RECENT = BIT(1),
+	IMAP_STATUS_ITEM_UIDNEXT = BIT(2),
+	IMAP_STATUS_ITEM_UIDVALIDITY = BIT(3),
+	IMAP_STATUS_ITEM_UNSEEN = BIT(4),
+	IMAP_STATUS_ITEM_HIGHESTMODSEQ = BIT(5),
+	IMAP_STATUS_ITEM_SIZE = BIT(6),
+
+	IMAP_STATUS_ITEM_X_SIZE = BIT(16), /* to be deprecated */
+	IMAP_STATUS_ITEM_X_GUID = BIT(17),
+};
+
+struct imap_status_items {
+	enum imap_status_item_flags flags;
+};
+
+struct imap_status_result {
+	struct mailbox_status status;
+	struct mailbox_metadata metadata;
+	enum mail_error error;
+	const char *errstr;
+};
+
+static inline bool
+imap_status_items_is_empty(const struct imap_status_items *items)
+{
+	return (items->flags == 0);
+}
+
+int imap_status_parse_items(struct client_command_context *cmd,
+			    const struct imap_arg *args,
+			    struct imap_status_items *items_r);
+
+int imap_status_get_result(struct client *client, struct mailbox *box,
+			   const struct imap_status_items *items,
+			   struct imap_status_result *result_r);
+int imap_status_get(struct client_command_context *cmd,
+		    struct mail_namespace *ns, const char *mailbox,
+		    const struct imap_status_items *items,
+		    struct imap_status_result *result_r);
+
+int imap_status_send(struct client *client, const char *mailbox_mutf7,
+		     const struct imap_status_items *items,
+		     const struct imap_status_result *result)
+	ATTR_NOWARN_UNUSED_RESULT;
+
+#endif
diff --git a/src/imap/imap-sync-private.h b/src/imap/imap-sync-private.h
new file mode 100644
index 0000000..b0b1715
--- /dev/null
+++ b/src/imap/imap-sync-private.h
@@ -0,0 +1,47 @@
+#ifndef IMAP_SYNC_PRIVATE_H
+#define IMAP_SYNC_PRIVATE_H
+
+#include "imap-sync.h"
+
+struct imap_client_sync_context {
+	/* if multiple commands are in progress, we may need to wait for them
+	   to finish before syncing mailbox. */
+	unsigned int counter;
+	enum mailbox_sync_flags flags;
+	enum imap_sync_flags imap_flags;
+	const char *tagline;
+};
+
+struct imap_sync_context {
+	struct client *client;
+	struct mailbox *box;
+        enum imap_sync_flags imap_flags;
+
+	struct mailbox_transaction_context *t;
+	struct mailbox_sync_context *sync_ctx;
+	struct mail *mail;
+
+	struct mailbox_status status;
+	struct mailbox_sync_status sync_status;
+
+	struct mailbox_sync_rec sync_rec;
+	ARRAY_TYPE(keywords) tmp_keywords;
+	ARRAY_TYPE(seq_range) expunges;
+	uint32_t seq;
+
+	ARRAY_TYPE(seq_range) search_adds, search_removes;
+	unsigned int search_update_idx;
+
+	unsigned int messages_count;
+
+	/* Module-specific contexts. */
+	ARRAY(union imap_module_context *) module_contexts;
+
+	bool failed:1;
+	bool finished:1;
+	bool no_newmail:1;
+	bool have_new_mails:1;
+	bool search_update_notifying:1;
+};
+
+#endif
diff --git a/src/imap/imap-sync.c b/src/imap/imap-sync.c
new file mode 100644
index 0000000..fc49ae7
--- /dev/null
+++ b/src/imap/imap-sync.c
@@ -0,0 +1,841 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "str.h"
+#include "ostream.h"
+#include "mail-user.h"
+#include "mail-storage.h"
+#include "mail-search-build.h"
+#include "imap-quote.h"
+#include "imap-util.h"
+#include "imap-fetch.h"
+#include "imap-notify.h"
+#include "imap-commands.h"
+#include "imap-sync-private.h"
+
+static void uids_to_seqs(struct mailbox *box, ARRAY_TYPE(seq_range) *uids)
+{
+	T_BEGIN {
+		ARRAY_TYPE(seq_range) seqs;
+		const struct seq_range *range;
+		uint32_t seq1, seq2;
+
+		t_array_init(&seqs, array_count(uids));
+		array_foreach(uids, range) {
+			mailbox_get_seq_range(box, range->seq1, range->seq2,
+					      &seq1, &seq2);
+			/* since we have to notify about expunged messages,
+			   we expect that all the referenced UIDs exist */
+			i_assert(seq1 != 0);
+			i_assert(seq2 - seq1 == range->seq2 - range->seq1);
+
+			seq_range_array_add_range(&seqs, seq1, seq2);
+		}
+		/* replace uids with seqs */
+		array_clear(uids);
+		array_append_array(uids, &seqs);
+
+	} T_END;
+}
+
+static int search_update_fetch_more(const struct imap_search_update *update)
+{
+	int ret;
+
+	if ((ret = imap_fetch_more_no_lock_update(update->fetch_ctx)) == 0)
+		return 0;
+	/* finished the FETCH */
+	if (imap_fetch_end(update->fetch_ctx) < 0)
+		return -1;
+	return ret;
+}
+
+static int
+imap_sync_send_fetch_to_search_update(struct imap_sync_context *ctx,
+				      const struct imap_search_update *update)
+{
+	struct mail_search_args *search_args;
+	struct mail_search_arg *arg;
+	ARRAY_TYPE(seq_range) seqs;
+
+	if (ctx->search_update_notifying)
+		return search_update_fetch_more(update);
+
+	i_assert(!update->fetch_ctx->state.fetching);
+
+	if (array_count(&ctx->search_adds) == 0 || !ctx->have_new_mails)
+		return 1;
+
+	search_args = mail_search_build_init();
+	arg = mail_search_build_add(search_args, SEARCH_UIDSET);
+	p_array_init(&arg->value.seqset, search_args->pool, 1);
+
+	/* find the newly appended messages: ctx->messages_count is the message
+	   count before new messages found by sync, client->messages_count is
+	   the number of messages after. */
+	t_array_init(&seqs, 1);
+	seq_range_array_add_range(&seqs, ctx->messages_count+1,
+				  ctx->client->messages_count);
+	mailbox_get_uid_range(ctx->client->mailbox, &seqs, &arg->value.seqset);
+	/* remove messages not in the search_adds list */
+	seq_range_array_intersect(&arg->value.seqset, &ctx->search_adds);
+
+	imap_fetch_begin(update->fetch_ctx, ctx->client->mailbox, search_args);
+	mail_search_args_unref(&search_args);
+	return search_update_fetch_more(update);
+}
+
+static int
+imap_sync_send_search_update(struct imap_sync_context *ctx,
+			     const struct imap_search_update *update,
+			     bool removes_only)
+{
+	string_t *cmd;
+	int ret = 1;
+
+	if (!ctx->search_update_notifying) {
+		mailbox_search_result_sync(update->result, &ctx->search_removes,
+					   &ctx->search_adds);
+	}
+	if (array_count(&ctx->search_adds) == 0 &&
+	    array_count(&ctx->search_removes) == 0)
+		return 1;
+
+	i_assert(array_count(&ctx->search_adds) == 0 || !removes_only);
+	if (update->fetch_ctx != NULL) {
+		ret = imap_sync_send_fetch_to_search_update(ctx, update);
+		if (ret == 0) {
+			ctx->search_update_notifying = TRUE;
+			return 0;
+		}
+	}
+	ctx->search_update_notifying = FALSE;
+
+	cmd = t_str_new(256);
+	str_append(cmd, "* ESEARCH (TAG ");
+	imap_append_string(cmd, update->tag);
+	str_append_c(cmd, ')');
+	if (update->return_uids)
+		str_append(cmd, " UID");
+	else {
+		/* convert to sequences */
+		uids_to_seqs(ctx->client->mailbox, &ctx->search_removes);
+		uids_to_seqs(ctx->client->mailbox, &ctx->search_adds);
+	}
+
+	if (array_count(&ctx->search_removes) != 0) {
+		str_printfa(cmd, " REMOVEFROM (0 ");
+		imap_write_seq_range(cmd, &ctx->search_removes);
+		str_append_c(cmd, ')');
+	}
+	if (array_count(&ctx->search_adds) != 0) {
+		str_printfa(cmd, " ADDTO (0 ");
+		imap_write_seq_range(cmd, &ctx->search_adds);
+		str_append_c(cmd, ')');
+	}
+	str_append(cmd, "\r\n");
+	o_stream_nsend(ctx->client->output, str_data(cmd), str_len(cmd));
+	return ret;
+}
+
+static int
+imap_sync_send_search_updates(struct imap_sync_context *ctx, bool removes_only)
+{
+	const struct imap_search_update *updates;
+	unsigned int i, count;
+	int ret = 1;
+
+	if (!array_is_created(&ctx->client->search_updates))
+		return 1;
+
+	if (!array_is_created(&ctx->search_removes)) {
+		i_array_init(&ctx->search_removes, 64);
+		i_array_init(&ctx->search_adds, 128);
+	}
+
+	updates = array_get(&ctx->client->search_updates, &count);
+	for (i = ctx->search_update_idx; i < count; i++) {
+		T_BEGIN {
+			ret = imap_sync_send_search_update(ctx, &updates[i],
+							   removes_only);
+		} T_END;
+		if (ret <= 0)
+			break;
+	}
+	ctx->search_update_idx = i;
+	return ret;
+}
+
+struct imap_sync_context *
+imap_sync_init(struct client *client, struct mailbox *box,
+	       enum imap_sync_flags imap_flags, enum mailbox_sync_flags flags)
+{
+	struct imap_sync_context *ctx;
+
+	i_assert(client->mailbox == box);
+
+	if (client->notify_immediate_expunges) {
+		/* NOTIFY enabled without SELECTED-DELAYED */
+		flags &= ENUM_NEGATE(MAILBOX_SYNC_FLAG_NO_EXPUNGES);
+	}
+
+	ctx = i_new(struct imap_sync_context, 1);
+	ctx->client = client;
+	ctx->box = box;
+	ctx->imap_flags = imap_flags;
+	i_array_init(&ctx->module_contexts, 5);
+
+	/* make sure user can't DoS the system by causing Dovecot to create
+	   tons of useless namespaces. */
+	mail_user_drop_useless_namespaces(client->user);
+
+	ctx->sync_ctx = mailbox_sync_init(box, flags);
+	ctx->t = mailbox_transaction_begin(box, 0, "Mailbox sync");
+	ctx->mail = mail_alloc(ctx->t, MAIL_FETCH_FLAGS, NULL);
+	ctx->messages_count = client->messages_count;
+	i_array_init(&ctx->tmp_keywords, client->keywords.announce_count + 8);
+
+	if (client_has_enabled(client, imap_feature_qresync)) {
+		i_array_init(&ctx->expunges, 128);
+		/* always send UIDs in FETCH replies */
+		ctx->imap_flags |= IMAP_SYNC_FLAG_SEND_UID;
+	}
+
+	client_send_mailbox_flags(client, FALSE);
+	/* send search updates the first time after sync is initialized.
+	   it now contains expunged messages that must be sent before
+	   EXPUNGE replies. */
+	if (imap_sync_send_search_updates(ctx, TRUE) == 0)
+		i_unreached();
+	ctx->search_update_idx = 0;
+	return ctx;
+}
+
+static void
+imap_sync_send_highestmodseq(struct imap_sync_context *ctx,
+			     struct client_command_context *sync_cmd)
+{
+	struct client *client = ctx->client;
+	uint64_t send_modseq = 0;
+
+	if (ctx->sync_status.sync_delayed_expunges &&
+	    client->highest_fetch_modseq > client->sync_last_full_modseq) {
+		/* if client updates highest-modseq using returned MODSEQs
+		   it loses expunges. try to avoid this by sending it a lower
+		   pre-expunge HIGHESTMODSEQ reply. */
+		send_modseq = client->sync_last_full_modseq;
+	} else if (!ctx->sync_status.sync_delayed_expunges &&
+		   ctx->status.highest_modseq > client->sync_last_full_modseq &&
+		   ctx->status.highest_modseq > client->highest_fetch_modseq) {
+		/* we've probably sent some VANISHED or EXISTS replies which
+		   increased the highest-modseq. notify the client about
+		   this. */
+		send_modseq = ctx->status.highest_modseq;
+	}
+
+	if (send_modseq == 0) {
+		/* no sending */
+	} else if (sync_cmd->sync != NULL && /* IDLE doesn't have ->sync */
+		   sync_cmd->sync->tagline != NULL && /* NOTIFY doesn't have tagline */
+		   str_begins(sync_cmd->sync->tagline, "OK ") &&
+		   sync_cmd->sync->tagline[3] != '[') {
+		/* modify the tagged reply directly */
+		sync_cmd->sync->tagline = p_strdup_printf(sync_cmd->pool,
+			"OK [HIGHESTMODSEQ %"PRIu64"] %s",
+			send_modseq, sync_cmd->sync->tagline + 3);
+	} else {
+		/* send an untagged OK reply */
+		client_send_line(client, t_strdup_printf(
+			"* OK [HIGHESTMODSEQ %"PRIu64"] Highest",
+			send_modseq));
+	}
+
+	if (!ctx->sync_status.sync_delayed_expunges) {
+		/* no delayed expunges, remember this for future */
+		client->sync_last_full_modseq = ctx->status.highest_modseq;
+	}
+	client->highest_fetch_modseq = 0;
+}
+
+static int imap_sync_finish(struct imap_sync_context *ctx, bool aborting)
+{
+	struct client *client = ctx->client;
+	int ret = ctx->failed ? -1 : 0;
+
+	if (ctx->finished)
+		return ret;
+	ctx->finished = TRUE;
+
+	mail_free(&ctx->mail);
+	/* the transaction is used only for fetching modseqs/flags.
+	   it can't really fail.. */
+	(void)mailbox_transaction_commit(&ctx->t);
+
+	if (array_is_created(&ctx->expunges))
+		array_free(&ctx->expunges);
+
+	if (mailbox_sync_deinit(&ctx->sync_ctx, &ctx->sync_status) < 0 ||
+	    ctx->failed) {
+		ctx->failed = TRUE;
+		ret = -1;
+	}
+	mailbox_get_open_status(ctx->box, STATUS_UIDVALIDITY |
+				STATUS_MESSAGES | STATUS_RECENT |
+				STATUS_HIGHESTMODSEQ, &ctx->status);
+
+	if (ctx->status.uidvalidity != client->uidvalidity) {
+		/* most clients would get confused by this. disconnect them. */
+		client_disconnect_with_error(client,
+					     "Mailbox UIDVALIDITY changed");
+	}
+	if (mailbox_is_inconsistent(ctx->box)) {
+		client_disconnect_with_error(client,
+			"IMAP session state is inconsistent, please relogin.");
+		/* we can't trust status information anymore, so don't try to
+		   sync message counts. */
+		return -1;
+	}
+	if (!ctx->no_newmail && !aborting) {
+		if (ctx->status.messages < ctx->messages_count)
+			i_panic("Message count decreased");
+		if (ctx->status.messages != ctx->messages_count &&
+		    client->notify_count_changes) {
+			client_send_line(client,
+				t_strdup_printf("* %u EXISTS", ctx->status.messages));
+			ctx->have_new_mails = TRUE;
+		}
+		if (ctx->status.recent != client->recent_count &&
+		    client->notify_count_changes) {
+			client_send_line(client,
+				t_strdup_printf("* %u RECENT", ctx->status.recent));
+		}
+		client->messages_count = ctx->status.messages;
+		client->recent_count = ctx->status.recent;
+	}
+	return ret;
+}
+
+static int imap_sync_notify_more(struct imap_sync_context *ctx)
+{
+	int ret = 1;
+
+	if (ctx->have_new_mails && ctx->client->notify_ctx != NULL) {
+		/* send FETCH replies for the new mails */
+		if ((ret = imap_client_notify_newmails(ctx->client)) == 0)
+			return 0;
+		if (ret < 0)
+			ctx->failed = TRUE;
+	}
+
+	/* send search updates the second time after syncing in done.
+	   now it contains added/removed messages. */
+	if ((ret = imap_sync_send_search_updates(ctx, FALSE)) < 0)
+		ctx->failed = TRUE;
+
+	if (ret > 0)
+		ret = ctx->client->v.sync_notify_more(ctx);
+	return ret;
+}
+
+int imap_sync_deinit(struct imap_sync_context *ctx,
+		     struct client_command_context *sync_cmd)
+{
+	int ret;
+
+	ret = imap_sync_finish(ctx, TRUE);
+	imap_client_notify_finished(ctx->client);
+
+	if (client_has_enabled(ctx->client, imap_feature_qresync) &&
+	    !ctx->client->nonpermanent_modseqs)
+		imap_sync_send_highestmodseq(ctx, sync_cmd);
+
+	if (array_is_created(&ctx->search_removes)) {
+		array_free(&ctx->search_removes);
+		array_free(&ctx->search_adds);
+	}
+
+	array_free(&ctx->tmp_keywords);
+	array_free(&ctx->module_contexts);
+	i_free(ctx);
+	return ret;
+}
+
+static void imap_sync_add_modseq(struct imap_sync_context *ctx, string_t *str)
+{
+	uint64_t modseq;
+
+	modseq = mail_get_modseq(ctx->mail);
+	if (ctx->client->highest_fetch_modseq < modseq)
+		ctx->client->highest_fetch_modseq = modseq;
+	str_printfa(str, "MODSEQ (%"PRIu64")", modseq);
+}
+
+static int imap_sync_send_flags(struct imap_sync_context *ctx, string_t *str)
+{
+	enum mail_flags flags;
+	const char *const *keywords;
+
+	mail_set_seq(ctx->mail, ctx->seq);
+	flags = mail_get_flags(ctx->mail);
+	keywords = client_get_keyword_names(ctx->client, &ctx->tmp_keywords,
+			mail_get_keyword_indexes(ctx->mail));
+
+	if ((flags & MAIL_DELETED) != 0)
+		ctx->client->sync_seen_deletes = TRUE;
+
+	str_truncate(str, 0);
+	str_printfa(str, "* %u FETCH (", ctx->seq);
+	if ((ctx->imap_flags & IMAP_SYNC_FLAG_SEND_UID) != 0)
+		str_printfa(str, "UID %u ", ctx->mail->uid);
+	if (client_has_enabled(ctx->client, imap_feature_condstore) &&
+	    !ctx->client->nonpermanent_modseqs) {
+		imap_sync_add_modseq(ctx, str);
+		str_append_c(str, ' ');
+	}
+	str_append(str, "FLAGS (");
+	imap_write_flags(str, flags, keywords);
+	str_append(str, "))");
+	return client_send_line_next(ctx->client, str_c(str));
+}
+
+static int imap_sync_send_modseq(struct imap_sync_context *ctx, string_t *str)
+{
+	mail_set_seq(ctx->mail, ctx->seq);
+
+	str_truncate(str, 0);
+	str_printfa(str, "* %u FETCH (", ctx->seq);
+	if ((ctx->imap_flags & IMAP_SYNC_FLAG_SEND_UID) != 0)
+		str_printfa(str, "UID %u ", ctx->mail->uid);
+	imap_sync_add_modseq(ctx, str);
+	str_append_c(str, ')');
+	return client_send_line_next(ctx->client, str_c(str));
+}
+
+static void imap_sync_vanished(struct imap_sync_context *ctx)
+{
+	const struct seq_range *seqs;
+	unsigned int i, count;
+	string_t *line;
+	uint32_t seq, prev_uid, start_uid;
+	bool comma = FALSE;
+
+	/* Convert expunge sequences to UIDs and send them in VANISHED line. */
+	seqs = array_get(&ctx->expunges, &count);
+	if (count == 0)
+		return;
+
+	line = t_str_new(256);
+	str_append(line, "* VANISHED ");
+	for (i = 0; i < count; i++) {
+		start_uid = 0; prev_uid = 0;
+		for (seq = seqs[i].seq1; seq <= seqs[i].seq2; seq++) {
+			mail_set_seq(ctx->mail, seq);
+			if (prev_uid == 0 || prev_uid + 1 != ctx->mail->uid) {
+				if (start_uid != 0) {
+					if (!comma)
+						comma = TRUE;
+					else
+						str_append_c(line, ',');
+					str_printfa(line, "%u", start_uid);
+					if (start_uid != prev_uid) {
+						str_printfa(line, ":%u",
+							    prev_uid);
+					}
+				}
+				start_uid = ctx->mail->uid;
+			}
+			prev_uid = ctx->mail->uid;
+		}
+		if (!comma)
+			comma = TRUE;
+		else
+			str_append_c(line, ',');
+		str_printfa(line, "%u", start_uid);
+		if (start_uid != prev_uid)
+			str_printfa(line, ":%u", prev_uid);
+	}
+	str_append(line, "\r\n");
+	o_stream_nsend(ctx->client->output, str_data(line), str_len(line));
+}
+
+static int imap_sync_send_expunges(struct imap_sync_context *ctx, string_t *str)
+{
+	int ret = 1;
+
+	if (!ctx->client->notify_count_changes) {
+		/* NOTIFY: MessageEvent not specified for selected mailbox */
+		return 1;
+	}
+
+	if (array_is_created(&ctx->expunges)) {
+		/* Use a single VANISHED line */
+		seq_range_array_add_range(&ctx->expunges,
+					  ctx->sync_rec.seq1,
+					  ctx->sync_rec.seq2);
+		return 1;
+	}
+	if (ctx->seq == 0)
+		ctx->seq = ctx->sync_rec.seq2;
+	for (; ctx->seq >= ctx->sync_rec.seq1; ctx->seq--) {
+		if (ret == 0) {
+			/* buffer full, continue later */
+			return 0;
+		}
+
+		str_truncate(str, 0);
+		str_printfa(str, "* %u EXPUNGE", ctx->seq);
+		ret = client_send_line_next(ctx->client, str_c(str));
+	}
+	return 1;
+}
+
+int imap_sync_more(struct imap_sync_context *ctx)
+{
+	string_t *str;
+	int ret = 1;
+
+	if (ctx->finished)
+		return imap_sync_notify_more(ctx);
+
+	/* finish syncing even when client has disconnected. otherwise our
+	   internal state (ctx->messages_count) can get messed up and unless
+	   we immediately stop handling all commands and syncs we could end up
+	   assert-crashing. */
+	str = t_str_new(256);
+	for (;;) {
+		if (ctx->seq == 0) {
+			/* get next one */
+			if (!mailbox_sync_next(ctx->sync_ctx, &ctx->sync_rec)) {
+				/* finished */
+				ret = 1;
+				break;
+			}
+		}
+
+		if (ctx->sync_rec.seq2 > ctx->messages_count) {
+			/* don't send change notifications of messages we
+			   haven't even announced to client yet */
+			if (ctx->sync_rec.seq1 > ctx->messages_count) {
+				ctx->seq = 0;
+				continue;
+			}
+			ctx->sync_rec.seq2 = ctx->messages_count;
+		}
+
+		/* EXPUNGEs must come last */
+		i_assert(!array_is_created(&ctx->expunges) ||
+			 array_count(&ctx->expunges) == 0 ||
+			 ctx->sync_rec.type == MAILBOX_SYNC_TYPE_EXPUNGE);
+		switch (ctx->sync_rec.type) {
+		case MAILBOX_SYNC_TYPE_FLAGS:
+			if (!ctx->client->notify_flag_changes) {
+				/* NOTIFY: FlagChange not specified for
+				   selected mailbox */
+				break;
+			}
+			if (ctx->seq == 0)
+				ctx->seq = ctx->sync_rec.seq1;
+
+			ret = 1;
+			for (; ctx->seq <= ctx->sync_rec.seq2; ctx->seq++) {
+				if (ret == 0)
+					break;
+
+				ret = imap_sync_send_flags(ctx, str);
+			}
+			break;
+		case MAILBOX_SYNC_TYPE_EXPUNGE:
+			ret = imap_sync_send_expunges(ctx, str);
+			if (ret > 0) {
+				/* update only after we're finished, so that
+				   the seq2 > messages_count check above
+				   doesn't break */
+				ctx->messages_count -=
+					ctx->sync_rec.seq2 -
+					ctx->sync_rec.seq1 + 1;
+			}
+			break;
+		case MAILBOX_SYNC_TYPE_MODSEQ:
+			if (!client_has_enabled(ctx->client, imap_feature_condstore))
+				break;
+			if (!ctx->client->notify_flag_changes) {
+				/* NOTIFY: FlagChange not specified for
+				   selected mailbox. The RFC doesn't explicitly
+				   specify MODSEQ changes, but they're close
+				   enough to flag changes. */
+				break;
+			}
+
+			if (ctx->seq == 0)
+				ctx->seq = ctx->sync_rec.seq1;
+
+			ret = 1;
+			for (; ctx->seq <= ctx->sync_rec.seq2; ctx->seq++) {
+				if (ret == 0)
+					break;
+
+				ret = imap_sync_send_modseq(ctx, str);
+			}
+			break;
+		}
+		if (ret == 0) {
+			/* buffer full */
+			break;
+		}
+
+		ctx->seq = 0;
+	}
+	if (ret > 0) {
+		if (array_is_created(&ctx->expunges))
+			imap_sync_vanished(ctx);
+		if (imap_sync_finish(ctx, FALSE) < 0)
+			return -1;
+		return imap_sync_more(ctx);
+	}
+	return ret;
+}
+
+bool imap_sync_is_allowed(struct client *client)
+{
+	if (client->syncing)
+		return FALSE;
+
+	if (client->mailbox != NULL &&
+	    mailbox_transaction_get_count(client->mailbox) > 0)
+		return FALSE;
+
+	return TRUE;
+}
+
+static bool cmd_finish_sync(struct client_command_context *cmd)
+{
+	if (cmd->sync->tagline != NULL)
+		client_send_tagline(cmd, cmd->sync->tagline);
+	return TRUE;
+}
+
+static bool cmd_sync_continue(struct client_command_context *sync_cmd)
+{
+	struct client_command_context *cmd, *prev;
+	struct client *client = sync_cmd->client;
+	struct imap_sync_context *ctx = sync_cmd->context;
+	int ret;
+
+	i_assert(ctx->client == client);
+
+	if ((ret = imap_sync_more(ctx)) == 0)
+		return FALSE;
+	if (ret < 0)
+		ctx->failed = TRUE;
+
+	client->syncing = FALSE;
+	if (imap_sync_deinit(ctx, sync_cmd) < 0) {
+		client_send_untagged_storage_error(client,
+			mailbox_get_storage(client->mailbox));
+	}
+	sync_cmd->context = NULL;
+
+	/* Finish all commands that waited for this sync. Go through the queue
+	   backwards, so that tagged replies are sent in the same order as
+	   they were received. This fixes problems with clients that rely on
+	   this (Apple Mail 3.2) */
+	for (cmd = client->command_queue; cmd->next != NULL; cmd = cmd->next) ;
+	for (; cmd != NULL; cmd = prev) {
+		prev = cmd->prev;
+
+		if (cmd->state == CLIENT_COMMAND_STATE_WAIT_SYNC &&
+		    cmd != sync_cmd &&
+		    cmd->sync->counter+1 == client->sync_counter) {
+			cmd_finish_sync(cmd);
+			client_command_free(&cmd);
+		}
+	}
+	cmd_finish_sync(sync_cmd);
+	return TRUE;
+}
+
+static void get_common_sync_flags(struct client *client,
+				  enum mailbox_sync_flags *flags_r,
+				  enum imap_sync_flags *imap_flags_r)
+{
+	struct client_command_context *cmd;
+	unsigned int count = 0, fast_count = 0, noexpunges_count = 0;
+
+	*flags_r = 0;
+	*imap_flags_r = 0;
+
+	for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {
+		if (cmd->sync != NULL &&
+		    cmd->sync->counter == client->sync_counter) {
+			if ((cmd->sync->flags & MAILBOX_SYNC_FLAG_FAST) != 0)
+				fast_count++;
+			if ((cmd->sync->flags & MAILBOX_SYNC_FLAG_NO_EXPUNGES) != 0)
+				noexpunges_count++;
+			*flags_r |= cmd->sync->flags;
+			*imap_flags_r |= cmd->sync->imap_flags;
+			count++;
+		}
+	}
+	i_assert(noexpunges_count == 0 || noexpunges_count == count);
+	if (fast_count != count)
+		*flags_r &= ENUM_NEGATE(MAILBOX_SYNC_FLAG_FAST);
+
+	i_assert((*flags_r & MAILBOX_SYNC_FLAG_FIX_INCONSISTENT) == 0);
+}
+
+static bool cmd_sync_client(struct client_command_context *sync_cmd)
+{
+	struct client *client = sync_cmd->client;
+	struct imap_sync_context *ctx;
+	enum mailbox_sync_flags flags;
+	enum imap_sync_flags imap_flags;
+	bool no_newmail;
+
+	/* there may be multiple commands waiting. use their combined flags */
+	get_common_sync_flags(client, &flags, &imap_flags);
+	client->sync_counter++;
+
+	no_newmail = (client->set->parsed_workarounds & WORKAROUND_DELAY_NEWMAIL) != 0 &&
+		client->notify_ctx == NULL && /* always disabled with NOTIFY */
+		(imap_flags & IMAP_SYNC_FLAG_SAFE) == 0;
+	if (no_newmail) {
+		/* expunges might break the client just as badly as new mail
+		   notifications. */
+		flags |= MAILBOX_SYNC_FLAG_NO_EXPUNGES;
+	}
+
+	client->syncing = TRUE;
+
+	ctx = imap_sync_init(client, client->mailbox, imap_flags, flags);
+	ctx->no_newmail = no_newmail;
+
+	/* handle the syncing using sync_cmd. it doesn't actually matter which
+	   one of the pending commands it is. */
+	sync_cmd->func = cmd_sync_continue;
+	sync_cmd->context = ctx;
+	sync_cmd->state = CLIENT_COMMAND_STATE_WAIT_OUTPUT;
+	if (!cmd_sync_continue(sync_cmd)) {
+		o_stream_set_flush_pending(client->output, TRUE);
+		return FALSE;
+	}
+
+	client_command_free(&sync_cmd);
+	cmd_sync_delayed(client);
+	return TRUE;
+}
+
+bool cmd_sync(struct client_command_context *cmd, enum mailbox_sync_flags flags,
+	      enum imap_sync_flags imap_flags, const char *tagline)
+{
+	struct client *client = cmd->client;
+
+	i_assert(client->output_cmd_lock == NULL);
+
+	if (cmd->cancel)
+		return TRUE;
+
+	cmd->stats.last_run_timeval = ioloop_timeval;
+	if (client->mailbox == NULL) {
+		/* no mailbox selected, no point in delaying the sync */
+		if (tagline != NULL)
+			client_send_tagline(cmd, tagline);
+		return TRUE;
+	}
+	cmd->tagline_reply = p_strdup(cmd->pool, tagline);
+
+	cmd->sync = p_new(cmd->pool, struct imap_client_sync_context, 1);
+	cmd->sync->counter = client->sync_counter;
+	cmd->sync->flags = flags;
+	cmd->sync->imap_flags = imap_flags;
+	cmd->sync->tagline = cmd->tagline_reply;
+	cmd->state = CLIENT_COMMAND_STATE_WAIT_SYNC;
+
+	cmd->func = NULL;
+	cmd->context = NULL;
+
+	if (client->input_lock == cmd)
+		client->input_lock = NULL;
+	return FALSE;
+}
+
+static bool cmd_sync_drop_fast(struct client *client)
+{
+	struct client_command_context *cmd, *prev;
+	bool ret = FALSE;
+
+	if (client->command_queue == NULL)
+		return FALSE;
+
+	for (cmd = client->command_queue; cmd->next != NULL; cmd = cmd->next) ;
+	for (; cmd != NULL; cmd = prev) {
+		prev = cmd->next;
+
+		if (cmd->state != CLIENT_COMMAND_STATE_WAIT_SYNC)
+			continue;
+
+		i_assert(cmd->sync != NULL);
+		if ((cmd->sync->flags & MAILBOX_SYNC_FLAG_FAST) != 0) {
+			cmd_finish_sync(cmd);
+			client_command_free(&cmd);
+			ret = TRUE;
+		}
+	}
+	return ret;
+}
+
+static bool cmd_sync_delayed_real(struct client *client)
+{
+	struct client_command_context *cmd, *first_expunge, *first_nonexpunge;
+
+	if (client->output_cmd_lock != NULL) {
+		/* wait until we can send output to client */
+		return FALSE;
+	}
+
+	if (!imap_sync_is_allowed(client)) {
+		/* wait until mailbox can be synced */
+		return cmd_sync_drop_fast(client);
+	}
+
+	/* separate syncs that can send expunges from those that can't */
+	first_expunge = first_nonexpunge = NULL;
+	for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {
+		if (cmd->sync != NULL &&
+		    cmd->sync->counter == client->sync_counter) {
+			if ((cmd->sync->flags & MAILBOX_SYNC_FLAG_NO_EXPUNGES) != 0) {
+				if (first_nonexpunge == NULL)
+					first_nonexpunge = cmd;
+			} else {
+				if (first_expunge == NULL)
+					first_expunge = cmd;
+			}
+		}
+	}
+	if (first_expunge != NULL && first_nonexpunge != NULL) {
+		/* sync expunges after nonexpunges */
+		for (cmd = first_expunge; cmd != NULL; cmd = cmd->next) {
+			if (cmd->sync != NULL &&
+			    cmd->sync->counter == client->sync_counter &&
+			    (cmd->sync->flags &
+			     MAILBOX_SYNC_FLAG_NO_EXPUNGES) == 0)
+				cmd->sync->counter++;
+		}
+		first_expunge = NULL;
+	}
+	cmd = first_nonexpunge != NULL ? first_nonexpunge : first_expunge;
+
+	if (cmd == NULL)
+		return cmd_sync_drop_fast(client);
+	i_assert(client->mailbox != NULL);
+	return cmd_sync_client(cmd);
+}
+
+bool cmd_sync_delayed(struct client *client)
+{
+	bool ret;
+
+	T_BEGIN {
+		ret = cmd_sync_delayed_real(client);
+	} T_END;
+	return ret;
+}
diff --git a/src/imap/imap-sync.h b/src/imap/imap-sync.h
new file mode 100644
index 0000000..a1c5198
--- /dev/null
+++ b/src/imap/imap-sync.h
@@ -0,0 +1,25 @@
+#ifndef IMAP_SYNC_H
+#define IMAP_SYNC_H
+
+enum imap_sync_flags {
+	IMAP_SYNC_FLAG_SEND_UID	= 0x01,
+	IMAP_SYNC_FLAG_SAFE	= 0x02
+};
+
+struct client;
+
+struct imap_sync_context *
+imap_sync_init(struct client *client, struct mailbox *box,
+	       enum imap_sync_flags imap_flags, enum mailbox_sync_flags flags);
+int imap_sync_deinit(struct imap_sync_context *ctx,
+		     struct client_command_context *sync_cmd);
+int imap_sync_more(struct imap_sync_context *ctx);
+
+/* Returns TRUE if syncing would be allowed currently. */
+bool imap_sync_is_allowed(struct client *client);
+
+bool cmd_sync(struct client_command_context *cmd, enum mailbox_sync_flags flags,
+	      enum imap_sync_flags imap_flags, const char *tagline);
+bool cmd_sync_delayed(struct client *client) ATTR_NOWARN_UNUSED_RESULT;
+
+#endif
diff --git a/src/imap/mail-storage-callbacks.c b/src/imap/mail-storage-callbacks.c
new file mode 100644
index 0000000..16c2d51
--- /dev/null
+++ b/src/imap/mail-storage-callbacks.c
@@ -0,0 +1,45 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "ostream.h"
+#include "mail-storage.h"
+#include "imap-commands-util.h"
+
+static void notify_ok(struct mailbox *mailbox ATTR_UNUSED,
+		      const char *text, void *context)
+{
+	struct client *client = context;
+
+	if (o_stream_get_buffer_used_size(client->output) != 0)
+		return;
+
+	T_BEGIN {
+		const char *str;
+
+		str = t_strconcat("* OK ", text, "\r\n", NULL);
+		o_stream_nsend_str(client->output, str);
+		(void)o_stream_flush(client->output);
+	} T_END;
+}
+
+static void notify_no(struct mailbox *mailbox ATTR_UNUSED,
+		      const char *text, void *context)
+{
+	struct client *client = context;
+
+	if (o_stream_get_buffer_used_size(client->output) != 0)
+		return;
+
+	T_BEGIN {
+		const char *str;
+
+		str = t_strconcat("* NO ", text, "\r\n", NULL);
+		o_stream_nsend_str(client->output, str);
+		(void)o_stream_flush(client->output);
+	} T_END;
+}
+
+struct mail_storage_callbacks mail_storage_callbacks = {
+	notify_ok,
+	notify_no
+};
diff --git a/src/imap/main.c b/src/imap/main.c
new file mode 100644
index 0000000..8efcfd4
--- /dev/null
+++ b/src/imap/main.c
@@ -0,0 +1,580 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "imap-common.h"
+#include "ioloop.h"
+#include "istream.h"
+#include "ostream.h"
+#include "path-util.h"
+#include "str.h"
+#include "base64.h"
+#include "process-title.h"
+#include "randgen.h"
+#include "restrict-access.h"
+#include "write-full.h"
+#include "settings-parser.h"
+#include "master-interface.h"
+#include "master-service.h"
+#include "master-login.h"
+#include "mail-user.h"
+#include "mail-storage-service.h"
+#include "smtp-submit-settings.h"
+#include "imap-master-client.h"
+#include "imap-resp-code.h"
+#include "imap-commands.h"
+#include "imap-feature.h"
+#include "imap-fetch.h"
+
+#include <stdio.h>
+#include <unistd.h>
+
+#define IS_STANDALONE() \
+        (getenv(MASTER_IS_PARENT_ENV) == NULL)
+
+#define IMAP_DIE_IDLE_SECS 10
+
+static bool verbose_proctitle = FALSE;
+static struct mail_storage_service_ctx *storage_service;
+static struct master_login *master_login = NULL;
+static struct timeout *to_proctitle;
+
+imap_client_created_func_t *hook_client_created = NULL;
+bool imap_debug = FALSE;
+
+struct event_category event_category_imap = {
+	.name = "imap",
+};
+
+imap_client_created_func_t *
+imap_client_created_hook_set(imap_client_created_func_t *new_hook)
+{
+	imap_client_created_func_t *old_hook = hook_client_created;
+
+	hook_client_created = new_hook;
+	return old_hook;
+}
+
+static void imap_refresh_proctitle_callback(void *context ATTR_UNUSED)
+{
+	timeout_remove(&to_proctitle);
+	imap_refresh_proctitle();
+}
+
+void imap_refresh_proctitle_delayed(void)
+{
+	if (to_proctitle == NULL)
+		to_proctitle = timeout_add_short(0,
+			imap_refresh_proctitle_callback, NULL);
+}
+
+void imap_refresh_proctitle(void)
+{
+#define IMAP_PROCTITLE_PREFERRED_LEN 80
+	struct client *client;
+	struct client_command_context *cmd;
+	string_t *title = t_str_new(128);
+	bool wait_output;
+
+	if (!verbose_proctitle)
+		return;
+
+	str_append_c(title, '[');
+	switch (imap_client_count) {
+	case 0:
+		str_append(title, "idling");
+		break;
+	case 1:
+		client = imap_clients;
+		str_append(title, client->user->username);
+		if (client->user->conn.remote_ip != NULL) {
+			str_append_c(title, ' ');
+			str_append(title,
+				   net_ip2addr(client->user->conn.remote_ip));
+		}
+		wait_output = FALSE;
+		for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {
+			if (cmd->name == NULL)
+				continue;
+
+			if (str_len(title) < IMAP_PROCTITLE_PREFERRED_LEN) {
+				str_append_c(title, ' ');
+				str_append(title, cmd->name);
+			}
+			if (cmd->state == CLIENT_COMMAND_STATE_WAIT_OUTPUT)
+				wait_output = TRUE;
+		}
+		if (wait_output) {
+			str_printfa(title, " - %zu bytes waiting",
+				    o_stream_get_buffer_used_size(client->output));
+			if (o_stream_is_corked(client->output))
+				str_append(title, " corked");
+		}
+		if (client->destroyed)
+			str_append(title, " (deinit)");
+		break;
+	default:
+		str_printfa(title, "%u connections", imap_client_count);
+		break;
+	}
+	str_append_c(title, ']');
+	process_title_set(str_c(title));
+}
+
+static void client_kill_idle(struct client *client)
+{
+	if (client->output_cmd_lock != NULL)
+		return;
+
+	mail_storage_service_io_activate_user(client->service_user);
+	client_send_line(client, "* BYE Server shutting down.");
+	client_destroy(client, "Server shutting down.");
+}
+
+static void imap_die(void)
+{
+	struct client *client, *next;
+	time_t last_io, now = time(NULL);
+	time_t stop_timestamp = now - IMAP_DIE_IDLE_SECS;
+	unsigned int stop_msecs;
+
+	for (client = imap_clients; client != NULL; client = next) {
+		next = client->next;
+
+		last_io = I_MAX(client->last_input, client->last_output);
+		if (last_io <= stop_timestamp)
+			client_kill_idle(client);
+		else {
+			timeout_remove(&client->to_idle);
+			stop_msecs = (last_io - stop_timestamp) * 1000;
+			client->to_idle = timeout_add(stop_msecs,
+						      client_kill_idle, client);
+		}
+	}
+}
+
+struct imap_login_request {
+	const char *tag;
+
+	const unsigned char *input;
+	size_t input_size;
+	bool send_untagged_capability;
+};
+
+static void
+client_parse_imap_login_request(const unsigned char *data, size_t len,
+				struct imap_login_request *input_r)
+{
+	size_t taglen;
+
+	i_zero(input_r);
+	if (len == 0)
+		return;
+
+	if (data[0] == '1')
+		input_r->send_untagged_capability = TRUE;
+	data++; len--;
+
+	input_r->tag = t_strndup(data, len);
+	taglen = strlen(input_r->tag) + 1;
+
+	if (len > taglen) {
+		input_r->input = data + taglen;
+		input_r->input_size = len - taglen;
+	}
+}
+
+static void
+client_send_login_reply(struct ostream *output, const char *capability_string,
+			const char *preauth_username,
+			const struct imap_login_request *request)
+{
+	string_t *reply = t_str_new(256);
+
+	/* cork/uncork around the OK reply to minimize latency */
+	o_stream_cork(output);
+	if (request->tag == NULL) {
+		str_printfa(reply, "* PREAUTH [CAPABILITY %s] Logged in as %s\r\n",
+			    capability_string, preauth_username);
+	} else if (capability_string == NULL) {
+		/* Client initialization failed. There's no need to send
+		   capabilities. Just send the tagged OK so the client knows
+		   the login itself succeeded, followed by a BYE. */
+		str_printfa(reply, "%s OK Logged in, but initialization failed.\r\n",
+			    request->tag);
+		str_append(reply, "* BYE "MAIL_ERRSTR_CRITICAL_MSG"\r\n");
+	} else if (request->send_untagged_capability) {
+		/* client doesn't seem to understand tagged capabilities. send
+		   untagged instead and hope that it works. */
+		str_printfa(reply, "* CAPABILITY %s\r\n", capability_string);
+		str_printfa(reply, "%s OK Logged in\r\n", request->tag);
+	} else {
+		str_printfa(reply, "%s OK [CAPABILITY %s] Logged in\r\n",
+			    request->tag, capability_string);
+	}
+	o_stream_nsend(output, str_data(reply), str_len(reply));
+	if (o_stream_uncork_flush(output) < 0 &&
+	    output->stream_errno != EPIPE)
+		i_error("write(client) failed: %s", o_stream_get_error(output));
+}
+
+static void
+client_add_input_finalize(struct client *client)
+{
+	struct ostream *output;
+
+	/* try to condense any responses into as few packets as possible */
+	output = client->output;
+	o_stream_ref(output);
+	o_stream_cork(output);
+	(void)client_handle_input(client);
+	o_stream_uncork(output);
+	o_stream_unref(&output);
+
+	/* we could have already handled LOGOUT, or we might need to continue
+	   pending ambiguous commands. */
+	client_continue_pending_input(client);
+}
+
+int client_create_from_input(const struct mail_storage_service_input *input,
+			     int fd_in, int fd_out,
+			     struct client **client_r, const char **error_r)
+{
+	struct mail_storage_service_input service_input;
+	struct mail_storage_service_user *user;
+	struct mail_user *mail_user;
+	struct client *client;
+	struct imap_settings *imap_set;
+	struct smtp_submit_settings *smtp_set;
+	struct event *event;
+	const char *errstr;
+
+	event = event_create(NULL);
+	event_add_category(event, &event_category_imap);
+	event_add_fields(event, (const struct event_add_field []){
+		{ .key = "user", .value = input->username },
+		{ .key = NULL }
+	});
+	if (input->local_ip.family != 0)
+		event_add_str(event, "local_ip", net_ip2addr(&input->local_ip));
+	if (input->local_port != 0)
+		event_add_int(event, "local_port", input->local_port);
+	if (input->remote_ip.family != 0)
+		event_add_str(event, "remote_ip", net_ip2addr(&input->remote_ip));
+	if (input->remote_port != 0)
+		event_add_int(event, "remote_port", input->remote_port);
+
+	service_input = *input;
+	service_input.event_parent = event;
+	if (mail_storage_service_lookup_next(storage_service, &service_input,
+					     &user, &mail_user, error_r) <= 0) {
+		event_unref(&event);
+		return -1;
+	}
+	/* Add the session only after creating the user, because
+	   input->session_id may be NULL */
+	event_add_str(event, "session", mail_user->session_id);
+
+	restrict_access_allow_coredumps(TRUE);
+
+	smtp_set = mail_storage_service_user_get_set(user)[1];
+	imap_set = mail_storage_service_user_get_set(user)[2];
+	if (imap_set->verbose_proctitle)
+		verbose_proctitle = TRUE;
+
+	if (settings_var_expand(&smtp_submit_setting_parser_info, smtp_set,
+				mail_user->pool, mail_user_var_expand_table(mail_user),
+				&errstr) <= 0 ||
+			settings_var_expand(&imap_setting_parser_info, imap_set,
+				mail_user->pool, mail_user_var_expand_table(mail_user),
+				&errstr) <= 0) {
+		*error_r = t_strdup_printf("Failed to expand settings: %s", errstr);
+		mail_user_deinit(&mail_user);
+		mail_storage_service_user_unref(&user);
+		event_unref(&event);
+		return -1;
+	}
+
+	client = client_create(fd_in, fd_out,
+			       event, mail_user, user, imap_set, smtp_set);
+	client->userdb_fields = input->userdb_fields == NULL ? NULL :
+		p_strarray_dup(client->pool, input->userdb_fields);
+	event_unref(&event);
+	*client_r = client;
+	return 0;
+}
+
+static void main_stdio_run(const char *username)
+{
+	struct client *client;
+	struct mail_storage_service_input input;
+	struct imap_login_request request;
+	const char *value, *error, *input_base64;
+
+	i_zero(&input);
+	input.module = input.service = "imap";
+	input.username = username != NULL ? username : getenv("USER");
+	if (input.username == NULL && IS_STANDALONE())
+		input.username = getlogin();
+	if (input.username == NULL)
+		i_fatal("USER environment missing");
+	if ((value = getenv("IP")) != NULL)
+		(void)net_addr2ip(value, &input.remote_ip);
+	if ((value = getenv("LOCAL_IP")) != NULL)
+		(void)net_addr2ip(value, &input.local_ip);
+
+	if (client_create_from_input(&input, STDIN_FILENO, STDOUT_FILENO,
+				     &client, &error) < 0)
+		i_fatal("%s", error);
+
+	input_base64 = getenv("CLIENT_INPUT");
+	if (input_base64 == NULL) {
+		/* IMAPLOGINTAG environment is compatible with mailfront */
+		i_zero(&request);
+		request.tag = getenv("IMAPLOGINTAG");
+	} else {
+		const buffer_t *input_buf = t_base64_decode_str(input_base64);
+		client_parse_imap_login_request(input_buf->data, input_buf->used,
+						&request);
+		if (request.input_size > 0) {
+			client_add_istream_prefix(client, request.input,
+						  request.input_size);
+		}
+	}
+
+	client_create_finish_io(client);
+	client_send_login_reply(client->output,
+				str_c(client->capability_string),
+				client->user->username, &request);
+	if (client_create_finish(client, &error) < 0)
+		i_fatal("%s", error);
+	client_add_input_finalize(client);
+	/* client may be destroyed now */
+}
+
+static void
+login_client_connected(const struct master_login_client *login_client,
+		       const char *username, const char *const *extra_fields)
+{
+#define MSG_BYE_INTERNAL_ERROR "* BYE "MAIL_ERRSTR_CRITICAL_MSG"\r\n"
+	struct mail_storage_service_input input;
+	struct client *client;
+	struct imap_login_request request;
+	enum mail_auth_request_flags flags = login_client->auth_req.flags;
+	const char *error;
+
+	i_zero(&input);
+	input.module = input.service = "imap";
+	input.local_ip = login_client->auth_req.local_ip;
+	input.remote_ip = login_client->auth_req.remote_ip;
+	input.local_port = login_client->auth_req.local_port;
+	input.remote_port = login_client->auth_req.remote_port;
+	input.username = username;
+	input.userdb_fields = extra_fields;
+	input.session_id = login_client->session_id;
+	if ((flags & MAIL_AUTH_REQUEST_FLAG_CONN_SECURED) != 0)
+		input.conn_secured = TRUE;
+	if ((flags & MAIL_AUTH_REQUEST_FLAG_CONN_SSL_SECURED) != 0)
+		input.conn_ssl_secured = TRUE;
+
+	client_parse_imap_login_request(login_client->data,
+					login_client->auth_req.data_size,
+					&request);
+
+	if (client_create_from_input(&input, login_client->fd, login_client->fd,
+				     &client, &error) < 0) {
+		int fd = login_client->fd;
+		struct ostream *output =
+			o_stream_create_fd_autoclose(&fd, IO_BLOCK_SIZE);
+		client_send_login_reply(output, NULL, NULL, &request);
+		o_stream_destroy(&output);
+
+		i_error("%s", error);
+		master_service_client_connection_destroyed(master_service);
+		return;
+	}
+	if ((flags & MAIL_AUTH_REQUEST_FLAG_TLS_COMPRESSION) != 0)
+		client->tls_compression = TRUE;
+	if (request.input_size > 0) {
+		client_add_istream_prefix(client, request.input,
+					  request.input_size);
+	}
+
+	/* The order here is important:
+	   1. Finish setting up rawlog, so all input/output is written there.
+	   2. Send tagged reply to login before any potentially long-running
+	      work (during which client could disconnect due to timeout).
+	   3. Finish initializing user, which can potentially take a long time.
+	*/
+	client_create_finish_io(client);
+	client_send_login_reply(client->output,
+				str_c(client->capability_string),
+				NULL, &request);
+	if (client_create_finish(client, &error) < 0) {
+		if (write_full(login_client->fd, MSG_BYE_INTERNAL_ERROR,
+			       strlen(MSG_BYE_INTERNAL_ERROR)) < 0)
+			if (errno != EAGAIN && errno != EPIPE)
+				e_error(client->event,
+					"write_full(client) failed: %m");
+
+		e_error(client->event, "%s", error);
+		client_destroy(client, error);
+		return;
+	}
+
+	client_add_input_finalize(client);
+	/* client may be destroyed now */
+}
+
+static void login_client_failed(const struct master_login_client *client,
+				const char *errormsg)
+{
+	struct imap_login_request request;
+	const char *msg;
+
+	client_parse_imap_login_request(client->data,
+					client->auth_req.data_size, &request);
+	msg = t_strdup_printf("%s NO ["IMAP_RESP_CODE_UNAVAILABLE"] %s\r\n",
+			      request.tag, errormsg);
+	if (write(client->fd, msg, strlen(msg)) < 0) {
+		/* ignored */
+	}
+}
+
+static void client_connected(struct master_service_connection *conn)
+{
+	/* when running standalone, we shouldn't even get here */
+	i_assert(master_login != NULL);
+
+	master_service_client_connection_accept(conn);
+	if (strcmp(conn->name, "imap-master") == 0) {
+		/* restoring existing IMAP connection (e.g. from imap-idle) */
+		imap_master_client_create(conn->fd);
+	} else {
+		master_login_add(master_login, conn->fd);
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	static const struct setting_parser_info *set_roots[] = {
+		&smtp_submit_setting_parser_info,
+		&imap_setting_parser_info,
+		NULL
+	};
+	struct master_login_settings login_set;
+	enum master_service_flags service_flags = 0;
+	enum mail_storage_service_flags storage_service_flags =
+		MAIL_STORAGE_SERVICE_FLAG_NO_SSL_CA |
+		/*
+		 * We include MAIL_STORAGE_SERVICE_FLAG_NO_NAMESPACES so
+		 * that the mail_user initialization is fast and we can
+		 * quickly send back the OK response to LOGIN/AUTHENTICATE.
+		 * Otherwise we risk a very slow namespace initialization to
+		 * cause client timeouts on login.
+		 */
+		MAIL_STORAGE_SERVICE_FLAG_NO_NAMESPACES;
+	const char *username = NULL, *auth_socket_path = "auth-master";
+	int c;
+
+	i_zero(&login_set);
+	login_set.postlogin_timeout_secs = MASTER_POSTLOGIN_TIMEOUT_DEFAULT;
+	login_set.request_auth_token = TRUE;
+
+	if (IS_STANDALONE() && getuid() == 0 &&
+	    net_getpeername(1, NULL, NULL) == 0) {
+		printf("* BAD [ALERT] imap binary must not be started from "
+		       "inetd, use imap-login instead.\n");
+		return 1;
+	}
+
+	if (IS_STANDALONE()) {
+		service_flags |= MASTER_SERVICE_FLAG_STANDALONE |
+			MASTER_SERVICE_FLAG_STD_CLIENT;
+	} else {
+		service_flags |= MASTER_SERVICE_FLAG_KEEP_CONFIG_OPEN;
+	}
+
+	master_service = master_service_init("imap", service_flags,
+					     &argc, &argv, "a:Dt:u:");
+	while ((c = master_getopt(master_service)) > 0) {
+		switch (c) {
+		case 'a':
+			auth_socket_path = optarg;
+			break;
+		case 't':
+			if (str_to_uint(optarg, &login_set.postlogin_timeout_secs) < 0 ||
+			    login_set.postlogin_timeout_secs == 0)
+				i_fatal("Invalid -t parameter: %s", optarg);
+			break;
+		case 'u':
+			storage_service_flags |=
+				MAIL_STORAGE_SERVICE_FLAG_USERDB_LOOKUP;
+			username = optarg;
+			break;
+		case 'D':
+			imap_debug = TRUE;
+			break;
+		default:
+			return FATAL_DEFAULT;
+		}
+	}
+
+	master_service_set_die_callback(master_service, imap_die);
+
+	/* plugins may want to add commands, so this needs to be called early */
+	commands_init();
+	imap_fetch_handlers_init();
+	imap_features_init();
+	clients_init();
+	imap_master_clients_init();
+
+	const char *error;
+	if (t_abspath(auth_socket_path, &login_set.auth_socket_path, &error) < 0)
+		i_fatal("t_abspath(%s) failed: %s", auth_socket_path, error);
+
+	if (argv[optind] != NULL) {
+		if (t_abspath(argv[optind], &login_set.postlogin_socket_path, &error) < 0)
+			i_fatal("t_abspath(%s) failed: %s", argv[optind], error);
+	}
+	login_set.callback = login_client_connected;
+	login_set.failure_callback = login_client_failed;
+
+	if (!IS_STANDALONE())
+		master_login = master_login_init(master_service, &login_set);
+
+	storage_service =
+		mail_storage_service_init(master_service,
+					  set_roots, storage_service_flags);
+	master_service_init_finish(master_service);
+	/* NOTE: login_set.*_socket_path are now invalid due to data stack
+	   having been freed */
+
+	/* fake that we're running, so we know if client was destroyed
+	   while handling its initial input */
+	io_loop_set_running(current_ioloop);
+
+	if (IS_STANDALONE()) {
+		T_BEGIN {
+			main_stdio_run(username);
+		} T_END;
+	} else {
+		io_loop_set_running(current_ioloop);
+	}
+
+	if (io_loop_is_running(current_ioloop))
+		master_service_run(master_service, client_connected);
+	clients_destroy_all();
+
+	if (master_login != NULL)
+		master_login_deinit(&master_login);
+	mail_storage_service_deinit(&storage_service);
+
+	imap_fetch_handlers_deinit();
+	imap_features_deinit();
+
+	commands_deinit();
+	imap_master_clients_deinit();
+
+	timeout_remove(&to_proctitle);
+	master_service_deinit(&master_service);
+	return 0;
+}
diff --git a/src/imap/test-imap-client-hibernate.c b/src/imap/test-imap-client-hibernate.c
new file mode 100644
index 0000000..6136019
--- /dev/null
+++ b/src/imap/test-imap-client-hibernate.c
@@ -0,0 +1,291 @@
+/* Copyright (c) 2020 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "test-common.h"
+#include "test-subprocess.h"
+#include "istream.h"
+#include "istream-unix.h"
+#include "strescape.h"
+#include "path-util.h"
+#include "unlink-directory.h"
+#include "settings-parser.h"
+#include "master-service.h"
+#include "smtp-submit.h"
+#include "mail-storage-service.h"
+#include "mail-storage-private.h"
+#include "imap-common.h"
+#include "imap-settings.h"
+#include "imap-client.h"
+
+#include <sys/stat.h>
+
+#define TEMP_DIRNAME ".test-imap-client-hibernate"
+
+#define EVILSTR "\t\r\n\001"
+
+struct test_imap_client_hibernate {
+	struct client *client;
+	int fd_listen;
+	bool has_mailbox;
+	const char *reply;
+};
+
+imap_client_created_func_t *hook_client_created = NULL;
+bool imap_debug = FALSE;
+
+static const char *tmpdir;
+static struct mail_storage_service_ctx *storage_service;
+
+void imap_refresh_proctitle(void) { }
+void imap_refresh_proctitle_delayed(void) { }
+int client_create_from_input(const struct mail_storage_service_input *input ATTR_UNUSED,
+			     int fd_in ATTR_UNUSED, int fd_out ATTR_UNUSED,
+			     struct client **client_r ATTR_UNUSED,
+			     const char **error_r ATTR_UNUSED) { return -1; }
+
+static int imap_hibernate_server(struct test_imap_client_hibernate *ctx)
+{
+	i_set_failure_prefix("SERVER: ");
+
+	int fd = net_accept(ctx->fd_listen, NULL, NULL);
+	i_assert(fd > 0);
+	struct istream *input = i_stream_create_unix(fd, SIZE_MAX);
+	i_stream_unix_set_read_fd(input);
+
+	/* send handshake */
+	const char *str = "VERSION\timap-hibernate\t1\t0\n";
+	if (write(fd, str, strlen(str)) != (ssize_t)strlen(str))
+		i_fatal("write(imap-hibernate client handshake) failed: %m");
+
+	/* read handshake */
+	const char *line;
+	if ((line = i_stream_read_next_line(input)) == NULL)
+		i_fatal("read(imap-hibernate client handshake) failed: %s",
+			i_stream_get_error(input));
+	if (strcmp(line, "VERSION\timap-hibernate\t1\t0") != 0)
+		i_fatal("VERSION not received");
+	/* read command */
+	if ((line = i_stream_read_next_line(input)) == NULL)
+		i_fatal("read(imap-hibernate client command) failed: %s",
+			i_stream_get_error(input));
+	int fd2 = i_stream_unix_get_read_fd(input);
+	test_assert(fd2 != -1);
+	i_close_fd(&fd2);
+	const char *const *args = t_strsplit_tabescaped(line);
+
+	/* write reply */
+	if (write(fd, ctx->reply, strlen(ctx->reply)) != (ssize_t)strlen(ctx->reply))
+		i_fatal("write(imap-hibernate client command) failed: %m");
+
+	if (ctx->has_mailbox) {
+		/* read mailbox notify fd */
+		i_stream_unix_set_read_fd(input);
+		if (i_stream_read_next_line(input) == NULL)
+			i_fatal("read(imap-hibernate notify fd) failed: %s",
+				i_stream_get_error(input));
+
+		fd2 = i_stream_unix_get_read_fd(input);
+		test_assert(fd2 != -1);
+		i_close_fd(&fd2);
+
+		if (write(fd, "+\n", 2) != 2)
+			i_fatal("write(imap-hibernate client command) failed: %m");
+	}
+
+	unsigned int i = 0;
+	test_assert_strcmp(args[i++], EVILSTR"testuser");
+	test_assert_strcmp(args[i++], EVILSTR"%u");
+	test_assert_strcmp(args[i++], "idle_notify_interval=120");
+	test_assert(str_begins(args[i++], "peer_dev_major="));
+	test_assert(str_begins(args[i++], "peer_dev_minor="));
+	test_assert(str_begins(args[i++], "peer_ino="));
+	test_assert_strcmp(args[i++], "session="EVILSTR"session");
+	test_assert(str_begins(args[i++], "session_created="));
+	test_assert_strcmp(args[i++], "lip=127.0.0.1");
+	test_assert_strcmp(args[i++], "lport=1234");
+	test_assert_strcmp(args[i++], "rip=127.0.0.2");
+	test_assert_strcmp(args[i++], "rport=5678");
+	test_assert(str_begins(args[i++], "uid="));
+	test_assert(str_begins(args[i++], "gid="));
+	if (ctx->has_mailbox)
+		test_assert_strcmp(args[i++], "mailbox="EVILSTR"mailbox");
+	test_assert_strcmp(args[i++], "tag="EVILSTR"tag");
+	test_assert(str_begins(args[i++], "stats="));
+	test_assert_strcmp(args[i++], "idle-cmd");
+	if (ctx->has_mailbox)
+		test_assert_strcmp(args[i++], "notify_fd");
+	test_assert(str_begins(args[i++], "state="));
+	test_assert(args[i] == NULL);
+
+	i_stream_unref(&input);
+	i_close_fd(&ctx->fd_listen);
+	i_close_fd(&fd);
+
+	ctx->client->hibernated = TRUE; /* prevent disconnect Info message */
+	client_destroy(ctx->client, NULL);
+
+	mail_storage_service_deinit(&storage_service);
+	master_service_deinit_forked(&master_service);
+	return 0;
+}
+
+static void
+mailbox_notify_callback(struct mailbox *box ATTR_UNUSED,
+			struct client *client ATTR_UNUSED)
+{
+}
+
+static void test_imap_client_hibernate(void)
+{
+	struct client *client;
+	struct smtp_submit_settings smtp_set;
+	struct mail_storage_service_user *service_user;
+	struct mail_user *mail_user;
+	struct test_imap_client_hibernate ctx;
+	const char *error;
+
+	storage_service = mail_storage_service_init(master_service, NULL,
+		MAIL_STORAGE_SERVICE_FLAG_ALLOW_ROOT |
+		MAIL_STORAGE_SERVICE_FLAG_NO_LOG_INIT |
+		MAIL_STORAGE_SERVICE_FLAG_NO_CHDIR |
+		MAIL_STORAGE_SERVICE_FLAG_NO_RESTRICT_ACCESS);
+
+	const char *const input_userdb[] = {
+		"mailbox_list_index=no",
+		t_strdup_printf("mail=mbox:%s/mbox", tmpdir),
+		NULL
+	};
+	struct mail_storage_service_input input = {
+		.username = EVILSTR"testuser",
+		.local_port = 1234,
+		.remote_port = 5678,
+		.userdb_fields = input_userdb,
+	};
+	test_assert(net_addr2ip("127.0.0.1", &input.local_ip) == 0);
+	test_assert(net_addr2ip("127.0.0.2", &input.remote_ip) == 0);
+	test_assert(mail_storage_service_lookup_next(storage_service, &input,
+		&service_user, &mail_user, &error) == 1);
+	mail_user->set->base_dir = tmpdir;
+	mail_user->set->mail_log_prefix = EVILSTR"%u";
+	mail_user->session_id = EVILSTR"session";
+	i_zero(&smtp_set);
+	i_zero(&ctx);
+
+	struct event *event = event_create(NULL);
+	int client_fd = dup(dev_null_fd);
+	client = client_create(client_fd, client_fd, event,
+			       mail_user, service_user,
+			       imap_setting_parser_info.defaults, &smtp_set);
+	ctx.client = client;
+
+	/* can't hibernate without IDLE */
+	test_begin("imap client hibernate: non-IDLE");
+	test_assert(!imap_client_hibernate(&client, &error));
+	test_assert_strcmp(error, "Non-IDLE connections not supported currently");
+	test_end();
+
+	struct client_command_context *cmd = client_command_alloc(client);
+	cmd->tag = EVILSTR"tag";
+	cmd->name = "IDLE";
+	event_unref(&event);
+
+	/* imap-hibernate socket doesn't exist */
+	test_begin("imap client hibernate: socket not found");
+	test_expect_error_string("/"TEMP_DIRNAME"/imap-hibernate) failed: No such file or directory");
+	test_assert(!imap_client_hibernate(&client, &error));
+	test_expect_no_more_errors();
+	test_assert(strstr(error, "net_connect_unix") != NULL);
+	test_end();
+
+	/* imap-hibernate socket times out */
+	const char *socket_path = t_strdup_printf("%s/imap-hibernate", tmpdir);
+	ctx.fd_listen = net_listen_unix(socket_path, 1);
+	if (ctx.fd_listen == -1)
+		i_fatal("net_listen_unix(%s) failed: %m", socket_path);
+	fd_set_nonblock(ctx.fd_listen, FALSE);
+
+	/* imap-hibernate socket returns failure */
+	test_begin("imap client hibernate: error returned");
+	ctx.reply = "-notgood\n";
+	test_subprocess_fork(imap_hibernate_server, &ctx, FALSE);
+
+	test_expect_error_string(TEMP_DIRNAME"/imap-hibernate returned failure: notgood");
+	test_assert(!imap_client_hibernate(&client, &error));
+	test_expect_no_more_errors();
+	test_assert(strstr(error, "notgood") != NULL);
+	test_end();
+
+	/* create and open evil mailbox */
+	client->mailbox = mailbox_alloc(client->user->namespaces->list,
+					"testbox", 0);
+	struct mailbox_update update = {
+		.uid_validity = 12345678,
+	};
+	memset(update.mailbox_guid, 0x12, sizeof(update.mailbox_guid));
+	test_assert(mailbox_create(client->mailbox, &update, FALSE) == 0);
+	test_assert(mailbox_open(client->mailbox) == 0);
+	client->mailbox->vname = EVILSTR"mailbox";
+
+	/* successful hibernation */
+	test_begin("imap client hibernate: success");
+	ctx.reply = "+\n";
+	ctx.has_mailbox = TRUE;
+	test_subprocess_fork(imap_hibernate_server, &ctx, FALSE);
+	/* start notification only after forking or we'll have trouble
+	   deinitializing cleanly */
+	mailbox_notify_changes(client->mailbox, mailbox_notify_callback, client);
+	test_assert(imap_client_hibernate(&client, &error));
+	test_end();
+
+	i_close_fd(&ctx.fd_listen);
+	mail_storage_service_deinit(&storage_service);
+}
+
+static void test_cleanup(void)
+{
+	const char *error;
+
+	if (unlink_directory(tmpdir, UNLINK_DIRECTORY_FLAG_RMDIR, &error) < 0)
+		i_error("unlink_directory() failed: %s", error);
+}
+
+static void test_init(void)
+{
+	const char *cwd, *error;
+
+	test_assert(t_get_working_dir(&cwd, &error) == 0);
+	tmpdir = t_strconcat(cwd, "/"TEMP_DIRNAME, NULL);
+
+	test_cleanup();
+	if (mkdir(tmpdir, 0700) < 0)
+		i_fatal("mkdir() failed: %m");
+
+	test_subprocesses_init(FALSE);
+}
+
+int main(int argc, char *argv[])
+{
+	const enum master_service_flags service_flags =
+		MASTER_SERVICE_FLAG_NO_CONFIG_SETTINGS |
+		MASTER_SERVICE_FLAG_STANDALONE |
+		MASTER_SERVICE_FLAG_STD_CLIENT |
+		MASTER_SERVICE_FLAG_DONT_SEND_STATS;
+	int ret;
+
+	master_service = master_service_init("test-imap-client-hibernate",
+					     service_flags, &argc, &argv, "D");
+
+	master_service_init_finish(master_service);
+	test_init();
+
+	static void (*const test_functions[])(void) = {
+		test_imap_client_hibernate,
+		NULL
+	};
+	ret = test_run(test_functions);
+
+	test_subprocesses_deinit();
+	test_cleanup();
+	master_service_deinit(&master_service);
+	return ret;
+}