path: root/src/lmtp/lmtp-commands.c

/* Copyright (c) 2009-2018 Dovecot authors, see the included COPYING file */

#include "lmtp-common.h"
#include "str.h"
#include "istream.h"
#include "istream-concat.h"
#include "ostream.h"
#include "iostream-temp.h"
#include "master-service.h"
#include "settings-parser.h"
#include "lda-settings.h"
#include "mail-user.h"
#include "smtp-address.h"
#include "mail-deliver.h"
#include "mail-error.h"
#include "lmtp-recipient.h"
#include "lmtp-proxy.h"
#include "lmtp-local.h"
#include "lmtp-commands.h"

/*
 * MAIL command
 */

int cmd_mail(void *conn_ctx,
	     struct smtp_server_cmd_ctx *cmd,
	     struct smtp_server_cmd_mail *data)
{
	struct client *client = (struct client *)conn_ctx;

	return client->v.cmd_mail(client, cmd, data);
}

int client_default_cmd_mail(struct client *client,
			    struct smtp_server_cmd_ctx *cmd ATTR_UNUSED,
			    struct smtp_server_cmd_mail *data ATTR_UNUSED)
{
	if (client->lmtp_set->lmtp_user_concurrency_limit > 0) {
		/* Connect to anvil before dropping privileges */
		lmtp_anvil_init();
	}
	return 1;
}

/*
 * RCPT command
 */

static int
cmd_rcpt_handle_forward_fields(struct smtp_server_cmd_ctx *cmd,
			       struct lmtp_recipient *lrcpt)
{
	struct smtp_server_recipient *rcpt = lrcpt->rcpt;
	string_t *xforward;
	const char *error;
	int ret;

	ret = smtp_params_rcpt_decode_extra(&rcpt->params,
					    LMTP_RCPT_FORWARD_PARAMETER,
					    &xforward, FALSE, &error);
	if (ret < 0) {
		smtp_server_reply(cmd, 501, "5.5.4",
				  "Invalid "LMTP_RCPT_FORWARD_PARAMETER"= "
				  "parameter: %s", error);
		return -1;
	}
	if (ret == 0)
		return 0;

	/* Drop the parameter */
	(void)smtp_params_rcpt_drop_extra(&rcpt->params,
					  LMTP_RCPT_FORWARD_PARAMETER, NULL);

	/* Check the real IP rather than the proxied client IP, since XCLIENT
	   command will update that, thereby making it untrusted. Unlike the
	   XCLIENT command, the RCPT forward parameter needs to be used after
	   the XCLIENT is first issued. */
	if (!smtp_server_connection_is_trusted(rcpt->conn)) {
		smtp_server_reply(cmd, 550, "5.7.14",
				  "Unacceptable "LMTP_RCPT_FORWARD_PARAMETER"= "
				  "parameter: You are not from trusted IP");
		return -1;
	}

	lrcpt->forward_fields = p_strdup(rcpt->pool, str_c(xforward));
	return 0;
}

int cmd_rcpt(void *conn_ctx, struct smtp_server_cmd_ctx *cmd,
	     struct smtp_server_recipient *rcpt)
{
	struct client *client = (struct client *)conn_ctx;
	struct smtp_server_transaction *trans;
	struct lmtp_recipient *lrcpt;

	trans = smtp_server_connection_get_transaction(rcpt->conn);
	i_assert(trans != NULL); /* MAIL command is synchronous */

	lrcpt = lmtp_recipient_create(client, trans, rcpt);

	if (cmd_rcpt_handle_forward_fields(cmd, lrcpt) < 0)
		return -1;

	return client->v.cmd_rcpt(client, cmd, lrcpt);
}

int client_default_cmd_rcpt(struct client *client,
			    struct smtp_server_cmd_ctx *cmd,
			    struct lmtp_recipient *lrcpt)
{
	struct smtp_server_recipient *rcpt = lrcpt->rcpt;
	const char *username, *detail;
	char delim = '\0';
	int ret;

	i_assert(!smtp_address_isnull(rcpt->path));
	if (*rcpt->path->localpart == '\0' && rcpt->path->domain == NULL) {
		smtp_server_recipient_reply(
			rcpt, 550, "5.1.1",
			"Unacceptable TO: Empty path not allowed");
		return -1;
	}

	smtp_address_detail_parse_temp(
		client->unexpanded_lda_set->recipient_delimiter,
		rcpt->path, &username, &delim, &detail);
	i_assert(*username != '\0');

	/* Make user name and detail available in the recipient event. The
	   mail_user event (for local delivery) also adds the user field, but
	   adding it here makes it available to the recipient event in general.
	   Additionally, the auth lookups performed for local and proxy delivery
	   can further override the "user" recipient event when the auth service
	   returns a different user name. In any case, we provide the initial
	   value here.
	 */
	event_add_str(rcpt->event, "user", username);
	if (detail[0] != '\0')
		event_add_str(rcpt->event, "detail", detail);

	if (client->lmtp_set->lmtp_proxy) {
		/* proxied? */
		if ((ret=lmtp_proxy_rcpt(client, cmd, lrcpt,
					 username, detail, delim)) != 0)
			return (ret < 0 ? -1 : 0);
		/* no */
	}

	/* local delivery */
	return lmtp_local_rcpt(client, cmd, lrcpt, username, detail);
}

/*
 * DATA command
 */

static void
cmd_data_create_added_headers(struct client *client,
			      struct smtp_server_cmd_ctx *cmd ATTR_UNUSED,
			      struct smtp_server_transaction *trans)
{
	size_t proxy_offset = 0;
	string_t *str;

	str = t_str_new(512);

	/* Headers for local deliveries only */
	if (client->local != NULL)
		lmtp_local_add_headers(client->local, trans, str);

	/* Headers for local and proxied messages */
	proxy_offset = str_len(str);
	if (client->lmtp_set->lmtp_add_received_header) {
		const struct lmtp_settings *lmtp_set = client->lmtp_set;
		enum smtp_server_trace_rcpt_to_address rcpt_to_address =
			SMTP_SERVER_TRACE_RCPT_TO_ADDRESS_FINAL;

		switch (lmtp_set->parsed_lmtp_hdr_delivery_address) {
		case LMTP_HDR_DELIVERY_ADDRESS_NONE:
			rcpt_to_address =
				SMTP_SERVER_TRACE_RCPT_TO_ADDRESS_NONE;
			break;
		case LMTP_HDR_DELIVERY_ADDRESS_FINAL:
			rcpt_to_address =
				SMTP_SERVER_TRACE_RCPT_TO_ADDRESS_FINAL;
			break;
		case LMTP_HDR_DELIVERY_ADDRESS_ORIGINAL:
			rcpt_to_address =
				SMTP_SERVER_TRACE_RCPT_TO_ADDRESS_ORIGINAL;
			break;
		}

		smtp_server_transaction_write_trace_record(
			str, trans, rcpt_to_address);
	}

	client->state.added_headers_local =
		p_strdup(client->state_pool, str_c(str));
	client->state.added_headers_proxy =
		client->state.added_headers_local + proxy_offset;
}

static int
cmd_data_finish(struct client *client,
		struct smtp_server_cmd_ctx *cmd,
		struct smtp_server_transaction *trans)
{
	struct client_state *state = &client->state;
	struct istream *input_msg;
	int ret;

	i_assert(HAS_ALL_BITS(trans->flags,
			      SMTP_SERVER_TRANSACTION_FLAG_REPLY_PER_RCPT));

	client->state.data_end_timeval = ioloop_timeval;

	/* finish the message */
	input_msg = iostream_temp_finish(&state->mail_data_output,
					 IO_BLOCK_SIZE);

	ret = client->v.cmd_data(client, cmd, trans,
				 input_msg, client->state.data_size);
	i_stream_unref(&input_msg);

	return ret;
}

int cmd_data_continue(void *conn_ctx, struct smtp_server_cmd_ctx *cmd,
		      struct smtp_server_transaction *trans)
{
	struct client *client = (struct client *)conn_ctx;
	struct client_state *state = &client->state;
	struct istream *data_input = state->data_input;
	const unsigned char *data;
	size_t size;
	ssize_t ret;

	i_assert(state->mail_data_output != NULL);

	while ((ret = i_stream_read(data_input)) > 0 || ret == -2) {
		data = i_stream_get_data(data_input, &size);
		if (o_stream_send(state->mail_data_output,
			data, size) != (ssize_t)size) {
			e_error(client->event, "write(%s) failed: %s",
				o_stream_get_name(state->mail_data_output),
				o_stream_get_error(state->mail_data_output));
			smtp_server_reply(cmd, 451, "4.3.0",
				"Temporary internal failure");
			return -1;
		}

		i_stream_skip(data_input, size);

		if (!smtp_server_cmd_data_check_size(cmd))
			return -1;
	}

	if (ret == 0)
		return 0;
	if (ret < 0 && data_input->stream_errno != 0) {
		/* Client probably disconnected */
		return -1;
	}

	/* Current data stream position is the data size */
	client->state.data_size = data_input->v_offset;

	/* The ending "." line was seen. finish delivery. */
	return cmd_data_finish(client, cmd, trans);
}

int cmd_data_begin(void *conn_ctx,
		   struct smtp_server_cmd_ctx *cmd ATTR_UNUSED,
		   struct smtp_server_transaction *trans ATTR_UNUSED,
		   struct istream *data_input)
{
	struct client *client = (struct client *)conn_ctx;
	string_t *path;

	i_assert(client->state.mail_data_output == NULL);

	path = t_str_new(256);
	mail_user_set_get_temp_prefix(path, client->raw_mail_user->set);
	client->state.mail_data_output = 
		iostream_temp_create_named(str_c(path), 0, "(lmtp data)");

	client->state.data_input = data_input;
	return 0;
}

int client_default_cmd_data(struct client *client,
			    struct smtp_server_cmd_ctx *cmd,
			    struct smtp_server_transaction *trans,
			    struct istream *data_input,
			    uoff_t data_size ATTR_UNUSED)
{
	struct client_state *state = &client->state;
	struct istream *input_local, *input_proxy;
	struct istream *inputs[3];

	/* Formulate prepended headers for both local and proxy delivery */
	cmd_data_create_added_headers(client, cmd, trans);

	/* Construct message streams for local and proxy delivery */
	input_local = input_proxy = NULL;
	if (client->local != NULL) {
		inputs[0] = i_stream_create_from_data(
			state->added_headers_local,
			strlen(state->added_headers_local));
		inputs[1] = data_input;
		inputs[2] = NULL;

		input_local = i_stream_create_concat(inputs);
		i_stream_set_name(input_local, "<lmtp DATA local>");
		i_stream_unref(&inputs[0]);
	}
	if (client->proxy != NULL) {
		inputs[0] = i_stream_create_from_data(
			state->added_headers_proxy,
			strlen(state->added_headers_proxy));
		inputs[1] = data_input;
		inputs[2] = NULL;

		input_proxy = i_stream_create_concat(inputs);
		i_stream_set_name(input_proxy, "<lmtp DATA proxy>");
		i_stream_unref(&inputs[0]);
	}

	/* local delivery */
	if (client->local != NULL) {
		lmtp_local_data(client, cmd, trans, input_local);
		i_stream_unref(&input_local);
	}
	/* proxy delivery */
	if (client->proxy != NULL) {
		lmtp_proxy_data(client, cmd, trans, input_proxy);
		i_stream_unref(&input_proxy);
	}
	return 0;
}