From a38f2f2a52822f150fff0d5e17e9f62582d6558c Mon Sep 17 00:00:00 2001
From: Victor Julien <vjulien@oisf.net>
Date: Sat, 25 Jun 2022 13:01:37 +0200
Subject: [PATCH] smtp: skip preprocessing for mime headers

Mime parser doesn't expect partial lines, which preprocessing can
provide. Add a check to let mime headers be handled by regular line
parsing.
---
 src/app-layer-smtp.c   | 5 +++++
 src/util-decode-mime.c | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/src/app-layer-smtp.c b/src/app-layer-smtp.c
index 44706b96e6..038800f9a2 100644
--- a/src/app-layer-smtp.c
+++ b/src/app-layer-smtp.c
@@ -1275,6 +1275,11 @@ static int SMTPPreProcessCommands(
 {
     DEBUG_VALIDATE_BUG_ON((state->parser_state & SMTP_PARSER_STATE_COMMAND_DATA_MODE) == 0);
 
+    /* fall back to strict line parsing for mime header parsing */
+    if (state->curr_tx && state->curr_tx->mime_state &&
+            state->curr_tx->mime_state->state_flag < HEADER_DONE)
+        return 1;
+
     bool line_complete = false;
     const int32_t input_len = input->len;
     for (int32_t i = 0; i < input_len; i++) {
diff --git a/src/util-decode-mime.c b/src/util-decode-mime.c
index 80fd9d9da6..64e300c9cc 100644
--- a/src/util-decode-mime.c
+++ b/src/util-decode-mime.c
@@ -1706,6 +1706,9 @@ static int FindMimeHeader(const uint8_t *buf, uint32_t blen,
     int finish_header = 0, new_header = 0;
     MimeDecConfig *mdcfg = MimeDecGetConfig();
 
+    /* should not get here with incomplete lines */
+    DEBUG_VALIDATE_BUG_ON(state->current_line_delimiter_len == 0);
+
     /* Find first header */
     hname = FindMimeHeaderStart(buf, blen, &hlen);
     if (hname != NULL) {