1 files changed, 474 insertions, 0 deletions

diff --git a/src/lib-mail/message-header-parser.c b/src/lib-mail/message-header-parser.c
new file mode 100644
index 0000000..c5026f1
--- /dev/null
+++ b/src/lib-mail/message-header-parser.c
@@ -0,0 +1,474 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "buffer.h"
+#include "istream.h"
+#include "str.h"
+#include "strfuncs.h"
+#include "unichar.h"
+#include "message-size.h"
+#include "message-header-parser.h"
+
+/* RFC 5322 2.1.1 and 2.2 */
+#define MESSAGE_HEADER_NAME_MAX_LEN 1000
+
+struct message_header_parser_ctx {
+	struct message_header_line line;
+
+	struct istream *input;
+	struct message_size *hdr_size;
+
+	string_t *name;
+	buffer_t *value_buf;
+
+	enum message_header_parser_flags flags;
+	bool skip_line:1;
+	bool has_nuls:1;
+};
+
+struct message_header_parser_ctx *
+message_parse_header_init(struct istream *input, struct message_size *hdr_size,
+			  enum message_header_parser_flags flags)
+{
+	struct message_header_parser_ctx *ctx;
+
+	ctx = i_new(struct message_header_parser_ctx, 1);
+	ctx->input = input;
+	ctx->hdr_size = hdr_size;
+	ctx->name = str_new(default_pool, 128);
+	ctx->flags = flags;
+	ctx->value_buf = buffer_create_dynamic(default_pool, 4096);
+	i_stream_ref(input);
+
+	if (hdr_size != NULL)
+		i_zero(hdr_size);
+	return ctx;
+}
+
+void message_parse_header_deinit(struct message_header_parser_ctx **_ctx)
+{
+	struct message_header_parser_ctx *ctx = *_ctx;
+
+	i_stream_unref(&ctx->input);
+	buffer_free(&ctx->value_buf);
+	str_free(&ctx->name);
+	i_free(ctx);
+
+	*_ctx = NULL;
+}
+
+int message_parse_header_next(struct message_header_parser_ctx *ctx,
+			      struct message_header_line **hdr_r)
+{
+        struct message_header_line *line = &ctx->line;
+	const unsigned char *msg;
+	size_t i, size, startpos, colon_pos, parse_size, skip = 0;
+	int ret;
+	bool continued, continues, last_no_newline, last_crlf;
+	bool no_newline, crlf_newline;
+
+	*hdr_r = NULL;
+	if (line->eoh)
+		return -1;
+
+	if (line->continues)
+		colon_pos = 0;
+	else {
+		/* new header line */
+		line->name_offset = ctx->input->v_offset;
+		colon_pos = UINT_MAX;
+		buffer_set_used_size(ctx->value_buf, 0);
+	}
+
+	no_newline = FALSE;
+	crlf_newline = FALSE;
+	continued = line->continues;
+	continues = FALSE;
+
+	for (startpos = 0;;) {
+		ret = i_stream_read_bytes(ctx->input, &msg, &size, startpos+2);
+		if (ret >= 0) {
+			/* we want to know one byte in advance to find out
+			   if it's multiline header */
+			parse_size = size == 0 ? 0 : size-1;
+		} else {
+			parse_size = size;
+		}
+
+		if (ret <= 0 && startpos == parse_size) {
+			if (ret == -1) {
+				if (startpos > 0) {
+					/* header ended unexpectedly. */
+					no_newline = TRUE;
+					skip = startpos;
+					break;
+				}
+				/* error / EOF with no bytes */
+				i_assert(skip == 0);
+				return -1;
+			}
+
+			if (size > 0 && !ctx->skip_line && !continued &&
+			    (msg[0] == '\n' ||
+			     (msg[0] == '\r' && size > 1 && msg[1] == '\n'))) {
+				/* end of headers - this mostly happens just
+				   with mbox where headers are read separately
+				   from body */
+				size = 0;
+				if (ctx->hdr_size != NULL)
+					ctx->hdr_size->lines++;
+				if (msg[0] == '\r') {
+					skip = 2;
+					crlf_newline = TRUE;
+				} else {
+					skip = 1;
+					if (ctx->hdr_size != NULL)
+						ctx->hdr_size->virtual_size++;
+				}
+				break;
+			}
+			if (ret == 0 && !ctx->input->eof) {
+				/* stream is nonblocking - need more data */
+				i_assert(skip == 0);
+				return 0;
+			}
+			i_assert(size > 0);
+
+			/* a) line is larger than input buffer
+			   b) header ended unexpectedly */
+			if (ret == -2) {
+				/* go back to last LWSP if found. */
+				size_t min_pos = !continued ? colon_pos : 0;
+				for (i = size-1; i > min_pos; i--) {
+					if (IS_LWSP(msg[i])) {
+						size = i;
+						break;
+					}
+				}
+				if (i == min_pos && (msg[size-1] == '\r' ||
+						     msg[size-1] == '\n')) {
+					/* we may or may not have a full header,
+					   but we don't know until we get the
+					   next character. leave out the
+					   linefeed and finish the header on
+					   the next run. */
+					size--;
+					if (size > 0 && msg[size-1] == '\r')
+						size--;
+				}
+				/* the buffer really has to be more than 2 to
+				   avoid CRLF looping forever */
+				i_assert(size > 0);
+
+				continues = TRUE;
+			}
+			no_newline = TRUE;
+			skip = size;
+			break;
+		}
+
+		/* find ':' */
+		if (colon_pos == UINT_MAX) {
+			for (i = startpos; i < parse_size; i++) {
+				if (msg[i] > ':')
+					continue;
+
+				if (msg[i] == ':' && !ctx->skip_line) {
+					colon_pos = i;
+					line->full_value_offset =
+						ctx->input->v_offset + i + 1;
+					break;
+				}
+				if (msg[i] == '\n') {
+					/* end of headers, or error */
+					break;
+				}
+
+				if (msg[i] == '\0')
+					ctx->has_nuls = TRUE;
+			}
+		} else {
+			i = startpos;
+		}
+
+		/* find '\n' */
+		for (; i < parse_size; i++) {
+			if (msg[i] <= '\n') {
+				if (msg[i] == '\n')
+					break;
+				if (msg[i] == '\0')
+					ctx->has_nuls = TRUE;
+			}
+		}
+
+		if (i < parse_size && i+1 == size && ret == -2) {
+			/* we don't know if the line continues. */
+			i++;
+		} else if (i < parse_size) {
+			/* got a line */
+			if (ctx->skip_line) {
+				/* skipping a line with a huge header name */
+				if (ctx->hdr_size != NULL) {
+					ctx->hdr_size->lines++;
+					ctx->hdr_size->physical_size += i + 1;
+					ctx->hdr_size->virtual_size += i + 1;
+				}
+				if (i == 0 || msg[i-1] != '\r') {
+					/* missing CR */
+					if (ctx->hdr_size != NULL)
+						ctx->hdr_size->virtual_size++;
+				}
+
+				i_stream_skip(ctx->input, i + 1);
+				startpos = 0;
+				ctx->skip_line = FALSE;
+				continue;
+			}
+			continues = i+1 < size && IS_LWSP(msg[i+1]);
+
+			if (ctx->hdr_size != NULL)
+				ctx->hdr_size->lines++;
+			if (i == 0 || msg[i-1] != '\r') {
+				/* missing CR */
+				if (ctx->hdr_size != NULL)
+					ctx->hdr_size->virtual_size++;
+				size = i;
+			} else {
+				size = i-1;
+				crlf_newline = TRUE;
+			}
+
+			skip = i+1;
+			break;
+		}
+
+		startpos = i;
+	}
+
+	last_crlf = line->crlf_newline &&
+		(ctx->flags & MESSAGE_HEADER_PARSER_FLAG_DROP_CR) == 0;
+	last_no_newline = line->no_newline ||
+		(ctx->flags & MESSAGE_HEADER_PARSER_FLAG_CLEAN_ONELINE) != 0;
+
+	line->continues = continues;
+	line->continued = continued;
+	line->crlf_newline = crlf_newline;
+	line->no_newline = no_newline;
+	if (size == 0 && !continued) {
+		/* end of headers */
+		line->eoh = TRUE;
+		line->name_len = line->value_len = line->full_value_len = 0;
+		line->name = ""; line->value = line->full_value = NULL;
+		line->middle = NULL; line->middle_len = 0;
+		line->full_value_offset = line->name_offset;
+		line->continues = FALSE;
+	} else if (line->continued) {
+		line->value = msg;
+		line->value_len = size;
+	} else if (colon_pos == UINT_MAX) {
+		/* missing ':', assume the whole line is value */
+		line->value = msg;
+		line->value_len = size;
+		line->full_value_offset = line->name_offset;
+
+		line->name = "";
+		line->name_len = 0;
+
+		line->middle = uchar_empty_ptr;
+		line->middle_len = 0;
+	} else {
+		size_t pos;
+
+		line->value = msg + colon_pos+1;
+		line->value_len = size - colon_pos - 1;
+		if ((ctx->flags & MESSAGE_HEADER_PARSER_FLAG_SKIP_INITIAL_LWSP) != 0) {
+			/* get value. skip all LWSP after ':'. Note that
+			   RFC2822 doesn't say we should, but history behind
+			   it..
+
+			   Exception to this is if the value consists only of
+			   LWSP, then skip only the one LWSP after ':'. */
+			for (pos = 0; pos < line->value_len; pos++) {
+				if (!IS_LWSP(line->value[pos]))
+					break;
+			}
+
+			if (pos == line->value_len) {
+				/* everything was LWSP */
+				if (line->value_len > 0 &&
+				    IS_LWSP(line->value[0]))
+					pos = 1;
+			}
+		} else {
+			pos = line->value_len > 0 &&
+				IS_LWSP(line->value[0]) ? 1 : 0;
+		}
+
+		line->value += pos;
+		line->value_len -= pos;
+		line->full_value_offset += pos;
+
+		/* get name, skip LWSP before ':' */
+		while (colon_pos > 0 && IS_LWSP(msg[colon_pos-1]))
+			colon_pos--;
+
+		/* Treat overlong header names as if the full header line was
+		   a value. Callers can usually handle large values better than
+		   large names. */
+		if (colon_pos > MESSAGE_HEADER_NAME_MAX_LEN) {
+			line->name = "";
+			line->name_len = 0;
+			line->middle = uchar_empty_ptr;
+			line->middle_len = 0;
+			line->value = msg;
+			line->value_len = size;
+			line->full_value_offset = line->name_offset;
+		} else {
+			str_truncate(ctx->name, 0);
+			/* use buffer_append() so the name won't be truncated if there
+			   are NULs. */
+			buffer_append(ctx->name, msg, colon_pos);
+			str_append_c(ctx->name, '\0');
+
+			/* keep middle stored also in ctx->name so it's available
+			   with use_full_value */
+			line->middle = msg + colon_pos;
+			line->middle_len = (size_t)(line->value - line->middle);
+			str_append_data(ctx->name, line->middle, line->middle_len);
+
+			line->name = str_c(ctx->name);
+			line->name_len = colon_pos;
+			line->middle = str_data(ctx->name) + line->name_len + 1;
+		}
+	}
+
+	if (!line->continued) {
+		/* first header line. make a copy of the line since we can't
+		   really trust input stream not to lose it. */
+		buffer_append(ctx->value_buf, line->value, line->value_len);
+		line->value = line->full_value = ctx->value_buf->data;
+		line->full_value_len = line->value_len;
+	} else if (line->use_full_value) {
+		/* continue saving the full value. */
+		if (last_no_newline) {
+			/* line is longer than fit into our buffer, so we
+			   were forced to break it into multiple
+			   message_header_lines */
+		} else {
+			if (last_crlf)
+				buffer_append_c(ctx->value_buf, '\r');
+			buffer_append_c(ctx->value_buf, '\n');
+		}
+		if ((ctx->flags & MESSAGE_HEADER_PARSER_FLAG_CLEAN_ONELINE) != 0 &&
+		    line->value_len > 0 && line->value[0] != ' ' &&
+		    IS_LWSP(line->value[0])) {
+			buffer_append_c(ctx->value_buf, ' ');
+			buffer_append(ctx->value_buf,
+				      line->value + 1, line->value_len - 1);
+		} else {
+			buffer_append(ctx->value_buf,
+				      line->value, line->value_len);
+		}
+		line->full_value = ctx->value_buf->data;
+		line->full_value_len = ctx->value_buf->used;
+	} else {
+		/* we didn't want full_value, and this is a continued line. */
+		line->full_value = NULL;
+		line->full_value_len = 0;
+	}
+
+	/* always reset it */
+	line->use_full_value = FALSE;
+
+	if (ctx->hdr_size != NULL) {
+		ctx->hdr_size->physical_size += skip;
+		ctx->hdr_size->virtual_size += skip;
+	}
+	i_stream_skip(ctx->input, skip);
+
+	*hdr_r = line;
+	return 1;
+}
+
+bool message_parse_header_has_nuls(const struct message_header_parser_ctx *ctx)
+{
+	return ctx->has_nuls;
+}
+
+#undef message_parse_header
+void message_parse_header(struct istream *input, struct message_size *hdr_size,
+			  enum message_header_parser_flags flags,
+			  message_header_callback_t *callback, void *context)
+{
+	struct message_header_parser_ctx *hdr_ctx;
+	struct message_header_line *hdr;
+	int ret;
+
+	hdr_ctx = message_parse_header_init(input, hdr_size, flags);
+	while ((ret = message_parse_header_next(hdr_ctx, &hdr)) > 0)
+		callback(hdr, context);
+	i_assert(ret != 0);
+	message_parse_header_deinit(&hdr_ctx);
+
+	/* call after the final skipping */
+	callback(NULL, context);
+}
+
+void message_header_line_write(buffer_t *output,
+			       const struct message_header_line *hdr)
+{
+	if (!hdr->continued) {
+		buffer_append(output, hdr->name, strlen(hdr->name));
+		buffer_append(output, hdr->middle, hdr->middle_len);
+	}
+	buffer_append(output, hdr->value, hdr->value_len);
+	if (!hdr->no_newline) {
+		if (hdr->crlf_newline)
+			buffer_append_c(output, '\r');
+		buffer_append_c(output, '\n');
+	}
+}
+
+const char *
+message_header_strdup(pool_t pool, const unsigned char *data, size_t size)
+{
+	if (memchr(data, '\0', size) == NULL) {
+		/* fast path */
+		char *dest = p_malloc(pool, size+1);
+		memcpy(dest, data, size);
+		return dest;
+	}
+
+	/* slow path - this could be made faster, but it should be
+	   rare so keep it simple */
+	string_t *str = str_new(pool, size+2);
+	for (size_t i = 0; i < size; i++) {
+		if (data[i] != '\0')
+			str_append_c(str, data[i]);
+		else
+			str_append(str, UNICODE_REPLACEMENT_CHAR_UTF8);
+	}
+	return str_c(str);
+}
+
+bool message_header_name_is_valid(const char *name)
+{
+	/*
+	  field-name      =   1*ftext
+
+	  ftext           =   %d33-57 /          ; Printable US-ASCII
+			      %d59-126           ;  characters not including
+						 ;  ":".
+	*/
+	for (unsigned int i = 0; name[i] != '\0'; i++) {
+		unsigned char c = name[i];
+		if (c >= 33 && c <= 57) {
+			/* before ":" */
+		} else if (c >= 59 && c <= 126) {
+			/* after ":" */
+		} else {
+			return FALSE;
+		}
+	}
+	return TRUE;
+}