[Fix] Html: Add entities collisions prevention logic (e.g. for mathml entities)

diff --git a/src/libserver/html.c b/src/libserver/html.c
index 518de98fad180a1b552b4e852a4368f2b106ef4d..a33e4e7fc8e3e0ea846de4d8fbe187b0e9819b45 100644 (file)
--- a/src/libserver/html.c
+++ b/src/libserver/html.c
@@ -208,9 +208,25 @@ rspamd_html_library_init (void)
 
                for (i = 0; i < G_N_ELEMENTS (tag_defs); i++) {
                        k = kh_put (tag_by_id, html_tag_by_id, tag_defs[i].id, &rc);
+
+                       if (rc == 0) {
+                               /* Collision by id */
+                               msg_err ("collision in html tag id: %d (%s) vs %d (%s)",
+                                               (int)tag_defs[i].id, tag_defs[i].name,
+                                               (int)kh_val (html_tag_by_id, k).id, kh_val (html_tag_by_id, k).name);
+                       }
+
                        kh_val (html_tag_by_id, k) = tag_defs[i];
 
                        k = kh_put (tag_by_name, html_tag_by_name, tag_defs[i].name, &rc);
+
+                       if (rc == 0) {
+                               /* Collision by name */
+                               msg_err ("collision in html tag name: %d (%s) vs %d (%s)",
+                                               (int)tag_defs[i].id, tag_defs[i].name,
+                                               (int)kh_val (html_tag_by_id, k).id, kh_val (html_tag_by_id, k).name);
+                       }
+
                        kh_val (html_tag_by_name, k) = tag_defs[i];
                }
 
@@ -229,11 +245,52 @@ rspamd_html_library_init (void)
                        if (entities_defs[i].code != 0) {
                                k = kh_put (entity_by_number, html_entity_by_number,
                                                entities_defs[i].code, &rc);
-                               kh_val (html_entity_by_number, k) = entities_defs[i].replacement;
+
+                               if (rc == 0) {
+                                       /* Collision by id */
+                                       gint cmp_res = strcmp (entities_defs[i].replacement,
+                                                       kh_val (html_entity_by_number, k));
+                                       if (cmp_res != 0) {
+                                               if (strlen (entities_defs[i].replacement) <
+                                                       strlen (kh_val (html_entity_by_number, k))) {
+                                                       /* Shorter replacement is more likely to be valid */
+                                                       msg_debug ("1 collision in html entity id: %d (%s); replace %s by %s",
+                                                                       (int) entities_defs[i].code, entities_defs[i].name,
+                                                                       kh_val (html_entity_by_number, k),
+                                                                       entities_defs[i].replacement);
+                                                       kh_val (html_entity_by_number, k) = entities_defs[i].replacement;
+                                               }
+                                               else if (strlen (entities_defs[i].replacement) ==
+                                                                strlen (kh_val (html_entity_by_number, k)) &&
+                                                                                cmp_res < 0) {
+                                                       /* Identical len but lexicographically shorter */
+                                                       msg_debug ("collision in html entity id: %d (%s); replace %s by %s",
+                                                                       (int) entities_defs[i].code, entities_defs[i].name,
+                                                                       kh_val (html_entity_by_number, k),
+                                                                       entities_defs[i].replacement);
+                                                       kh_val (html_entity_by_number, k) = entities_defs[i].replacement;
+                                               }
+                                               /* Do not replace otherwise */
+                                       }
+                                       /* Identic replacement */
+                               }
+                               else {
+                                       kh_val (html_entity_by_number, k) = entities_defs[i].replacement;
+                               }
                        }
 
                        k = kh_put (entity_by_name, html_entity_by_name,
                                        entities_defs[i].name, &rc);
+
+                       if (rc == 0) {
+                               /* Collision by name */
+                               if (strcmp (kh_val (html_entity_by_number, k),
+                                               entities_defs[i].replacement) != 0) {
+                                       msg_err ("collision in html entity name: %d (%s)",
+                                                       (int) entities_defs[i].code, entities_defs[i].name);
+                               }
+                       }
+
                        kh_val (html_entity_by_name, k) = entities_defs[i].replacement;
                }