[Fix] Filter invalid domains in fuzzy extra data

Issue: #5446

diff --git a/src/plugins/fuzzy_check.c b/src/plugins/fuzzy_check.c
index ece9a91e0657a56c08b3c21aedde9e6e1703089a..4ed94a141d363d3396cf6fc390a816504ea8b111 100644 (file)
--- a/src/plugins/fuzzy_check.c
+++ b/src/plugins/fuzzy_check.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 Vsevolod Stakhov
+ * Copyright 2025 Vsevolod Stakhov
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -1715,26 +1715,30 @@ fuzzy_cmd_write_extensions(struct rspamd_task *task,
                struct rspamd_email_address *addr = g_ptr_array_index(MESSAGE_FIELD(task,
                                                                                                                                                        from_mime),
                                                                                                                          0);
-               unsigned int to_write = MIN(MAX_FUZZY_DOMAIN, addr->domain_len) + 2;
 
-               if (to_write > 0 && to_write <= available) {
-                       *dest++ = RSPAMD_FUZZY_EXT_SOURCE_DOMAIN;
-                       *dest++ = to_write - 2;
+               if (addr->domain_len > 0) {
+                       /* Filter invalid domains */
+                       unsigned int to_write = MIN(MAX_FUZZY_DOMAIN, addr->domain_len) + 2;
 
-                       if (addr->domain_len < MAX_FUZZY_DOMAIN) {
-                               memcpy(dest, addr->domain, addr->domain_len);
-                               dest += addr->domain_len;
-                       }
-                       else {
-                               /* Trim from left */
-                               memcpy(dest,
-                                          addr->domain + (addr->domain_len - MAX_FUZZY_DOMAIN),
-                                          MAX_FUZZY_DOMAIN);
-                               dest += MAX_FUZZY_DOMAIN;
-                       }
+                       if (to_write > 0 && to_write <= available) {
+                               *dest++ = RSPAMD_FUZZY_EXT_SOURCE_DOMAIN;
+                               *dest++ = to_write - 2;
 
-                       available -= to_write;
-                       written += to_write;
+                               if (addr->domain_len < MAX_FUZZY_DOMAIN) {
+                                       memcpy(dest, addr->domain, addr->domain_len);
+                                       dest += addr->domain_len;
+                               }
+                               else {
+                                       /* Trim from left */
+                                       memcpy(dest,
+                                                  addr->domain + (addr->domain_len - MAX_FUZZY_DOMAIN),
+                                                  MAX_FUZZY_DOMAIN);
+                                       dest += MAX_FUZZY_DOMAIN;
+                               }
+
+                               available -= to_write;
+                               written += to_write;
+                       }
                }
        }