[Fix] Fix inconsistent nesting in mime parts

We should do like MUAs do: imlicitly close incomplete mime parts
and treat them as ususal. It is weird and utterly stupid but that's
what MUA do.

Issue: #4740
Closes: #4740

diff --git a/src/libmime/mime_parser.c b/src/libmime/mime_parser.c
index e753f6377c28b9b21475b9fde537791918d52e0d..ac35cffe3bd28a0e0ab07d65732c15441b4a76e0 100644 (file)
--- a/src/libmime/mime_parser.c
+++ b/src/libmime/mime_parser.c
@@ -1055,6 +1055,7 @@ rspamd_multipart_boundaries_filter(struct rspamd_task *task,
        goffset last_offset;
        unsigned int i, sel = 0;
        enum rspamd_mime_parse_error ret;
+       bool enforce_closing = false;
 
        last_offset = (multipart->raw_data.begin - st->start) +
                                  multipart->raw_data.len;
@@ -1099,6 +1100,12 @@ rspamd_multipart_boundaries_filter(struct rspamd_task *task,
                cur = &g_array_index(st->boundaries, struct rspamd_mime_boundary, i);
 
                if (cur->boundary > last_offset) {
+                       /*
+                        * We have reached the end of the part, so we have to close it implicitly
+                        * like MUA do
+                        */
+                       task->flags |= RSPAMD_TASK_FLAG_BROKEN_HEADERS;
+                       enforce_closing = true;
                        break;
                }
 
@@ -1136,7 +1143,7 @@ rspamd_multipart_boundaries_filter(struct rspamd_task *task,
                }
        }
 
-       if (i == st->boundaries->len && cb->cur_boundary) {
+       if (enforce_closing || (i == st->boundaries->len && cb->cur_boundary)) {
                /* Process the last part */
                struct rspamd_mime_boundary fb;