From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Tue, 25 May 2021 17:03:53 +0000 (+0300)
Subject: lib-mail: Add MESSAGE_PART_FLAG_OVERFLOW to MIME parts that reached parsing limits
X-Git-Tag: 2.3.16~64
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2d676b00071d031e523b48eda7e4cfd810d23189;p=thirdparty%2Fdovecot%2Fcore.git

lib-mail: Add MESSAGE_PART_FLAG_OVERFLOW to MIME parts that reached parsing limits

This allows callers to find out which MIME parts were properly parsed.
---

diff --git a/src/lib-mail/message-parser.c b/src/lib-mail/message-parser.c
index 6e45fe2caf..9a9c9a3515 100644
--- a/src/lib-mail/message-parser.c
+++ b/src/lib-mail/message-parser.c
@@ -253,6 +253,7 @@ boundary_line_find(struct message_parser_ctx *ctx,
 	if (ctx->total_parts_count >= ctx->max_total_mime_parts) {
 		/* can't add any more MIME parts. just stop trying to find
 		   more boundaries. */
+		ctx->part->flags |= MESSAGE_PART_FLAG_OVERFLOW;
 		return -1;
 	}
 
@@ -597,6 +598,7 @@ static int parse_next_header(struct message_parser_ctx *ctx,
 			parse_next_body_multipart_init(ctx);
 			ctx->multipart = TRUE;
 		} else {
+			part->flags |= MESSAGE_PART_FLAG_OVERFLOW;
 			part->flags &= ENUM_NEGATE(MESSAGE_PART_FLAG_MULTIPART);
 		}
 	}
@@ -702,11 +704,19 @@ static int parse_next_header(struct message_parser_ctx *ctx,
 		i_assert(ctx->last_boundary == NULL);
 		ctx->multipart = FALSE;
 		ctx->parse_next_block = parse_next_body_to_boundary;
-	} else if ((part->flags & MESSAGE_PART_FLAG_MESSAGE_RFC822) != 0 &&
-		   !parse_too_many_nested_mime_parts(ctx) &&
+	} else if ((part->flags & MESSAGE_PART_FLAG_MESSAGE_RFC822) == 0) {
+		/* Not message/rfc822 */
+		if (ctx->boundaries != NULL)
+			ctx->parse_next_block = parse_next_body_to_boundary;
+		else
+			ctx->parse_next_block = parse_next_body_to_eof;
+	} else if (!parse_too_many_nested_mime_parts(ctx) &&
 		   ctx->total_parts_count < ctx->max_total_mime_parts) {
+		/* message/rfc822 - not reached MIME part limits yet */
 		ctx->parse_next_block = parse_next_body_message_rfc822_init;
 	} else {
+		/* message/rfc822 - already reached MIME part limits */
+		part->flags |= MESSAGE_PART_FLAG_OVERFLOW;
 		part->flags &= ENUM_NEGATE(MESSAGE_PART_FLAG_MESSAGE_RFC822);
 		if (ctx->boundaries != NULL)
 			ctx->parse_next_block = parse_next_body_to_boundary;
diff --git a/src/lib-mail/message-part.h b/src/lib-mail/message-part.h
index 7f6afa3748..d8f99ab5d7 100644
--- a/src/lib-mail/message-part.h
+++ b/src/lib-mail/message-part.h
@@ -21,7 +21,11 @@ enum message_part_flags {
 	MESSAGE_PART_FLAG_HAS_NULS		= 0x20,
 
 	/* Mime-Version header exists. */
-	MESSAGE_PART_FLAG_IS_MIME		= 0x40
+	MESSAGE_PART_FLAG_IS_MIME		= 0x40,
+	/* Message parsing was aborted because there were too many MIME parts.
+	   This MIME part points to a blob which wasn't actually parsed to
+	   see if it would contain further MIME parts. */
+	MESSAGE_PART_FLAG_OVERFLOW		= 0x80,
 };
 
 struct message_part {
diff --git a/src/lib-mail/test-message-parser.c b/src/lib-mail/test-message-parser.c
index c4e117afc7..663bfe8c5a 100644
--- a/src/lib-mail/test-message-parser.c
+++ b/src/lib-mail/test-message-parser.c
@@ -965,7 +965,8 @@ static const char input_msg[] =
 
 	part = parts->children;
 	test_assert(part->children_count == 0);
-	test_assert(part->flags == MESSAGE_PART_FLAG_IS_MIME);
+	test_assert(part->flags == (MESSAGE_PART_FLAG_IS_MIME |
+				    MESSAGE_PART_FLAG_OVERFLOW));
 	test_assert(part->header_size.lines == 2);
 	test_assert(part->header_size.physical_size == 45);
 	test_assert(part->header_size.virtual_size == 45+2);
@@ -1029,7 +1030,8 @@ static const char input_msg[] =
 
 	part = parts->children;
 	test_assert(part->children_count == 0);
-	test_assert(part->flags == MESSAGE_PART_FLAG_IS_MIME);
+	test_assert(part->flags == (MESSAGE_PART_FLAG_IS_MIME |
+				    MESSAGE_PART_FLAG_OVERFLOW));
 	test_assert(part->header_size.lines == 2);
 	test_assert(part->header_size.physical_size == 30);
 	test_assert(part->header_size.virtual_size == 30+2);
@@ -1113,7 +1115,9 @@ static const char input_msg[] =
 
 	part = parts->children->children->next;
 	test_assert(part->children_count == 0);
-	test_assert(part->flags == (MESSAGE_PART_FLAG_TEXT | MESSAGE_PART_FLAG_IS_MIME));
+	test_assert(part->flags == (MESSAGE_PART_FLAG_TEXT |
+				    MESSAGE_PART_FLAG_IS_MIME |
+				    MESSAGE_PART_FLAG_OVERFLOW));
 	test_assert(part->header_size.lines == 2);
 	test_assert(part->header_size.physical_size == 26);
 	test_assert(part->header_size.virtual_size == 26+2);
@@ -1194,7 +1198,8 @@ static const char input_msg[] =
 
 	part = parts->children->children;
 	test_assert(part->children_count == 0);
-	test_assert(part->flags == MESSAGE_PART_FLAG_IS_MIME);
+	test_assert(part->flags == (MESSAGE_PART_FLAG_IS_MIME |
+				    MESSAGE_PART_FLAG_OVERFLOW));
 	test_assert(part->header_size.lines == 2);
 	test_assert(part->header_size.physical_size == 30);
 	test_assert(part->header_size.virtual_size == 30+2);
@@ -1277,7 +1282,9 @@ static const char *const input_msgs[] = {
 		part = part->children;
 
 		test_assert_idx(part->children_count == 0, i);
-		test_assert_idx(part->flags == 72, i);
+		test_assert_idx(part->flags == (MESSAGE_PART_FLAG_TEXT |
+						MESSAGE_PART_FLAG_IS_MIME |
+						MESSAGE_PART_FLAG_OVERFLOW), i);
 		test_assert_idx(part->header_size.lines == 2, i);
 		test_assert_idx(part->header_size.physical_size == 26, i);
 		test_assert_idx(part->header_size.virtual_size == 28, i);