fix: more issue #112 follow-ups (stanza-id disco gate, account sanitizer)

- xmpp: gate XEP-0359 stanza-id dedup on disco urn:xmpp:sid:0. Before
  honoring <stanza-id by='…'/> for archive_id dedup, check that the entity
  in `by` (or its domain — that's what profanity disco's on connect)
  announces the namespace; fall back to no-dedup when caps are unknown,
  matching the XEP §6 disco-gate (#1).
- accounts: narrow group-name sanitizer to only the characters GKeyFile
  actually forbids in group headers (`[`, `]`, `\n`, `\r`); `=` and `#` are
  valid inside a header and stay (#2).
- functional tests cover both branches of the disco gate — replayed
  stanza-id is flagged as duplicate when sid:0 is announced, and not
  flagged when it isn't.

Refs #112

src/config/accounts.c

@@ -43,8 +43,8 @@ _sanitize_account_name(const char* const name)
     gchar* sanitized = g_strdup(name);
     gchar* p = sanitized;
     while (*p) {
-        // GKeyFile special characters: [ ] = # \n \r
+        // GKeyFile group header forbids these characters.
-        if (*p == '[' || *p == ']' || *p == '=' || *p == '#' || *p == '\n' || *p == '\r') {
+        if (*p == '[' || *p == ']' || *p == '\n' || *p == '\r') {
             *p = '_';
         }
         p++;

src/xmpp/message.c

@@ -65,6 +65,7 @@ static void _handle_pubsub(xmpp_stanza_t* const stanza, xmpp_stanza_t* const eve
 static gboolean _handle_form(xmpp_stanza_t* const stanza);
 static gboolean _handle_jingle_message(xmpp_stanza_t* const stanza);
 static gboolean _should_ignore_based_on_silence(xmpp_stanza_t* const stanza);
+static gboolean _stanza_id_by_trusted(const char* by);
 #ifdef HAVE_OMEMO
 static void _receive_omemo(xmpp_stanza_t* const stanza, ProfMessage* message);
 #endif
@@ -1088,7 +1089,7 @@ _handle_groupchat(xmpp_stanza_t* const stanza)
     xmpp_stanza_t* stanzaidst = xmpp_stanza_get_child_by_name_and_ns(stanza, STANZA_NAME_STANZA_ID, STANZA_NS_STABLE_ID);
     if (stanzaidst) {
         const char* by = xmpp_stanza_get_attribute(stanzaidst, "by");
-        if (by && (g_strcmp0(by, from_jid->barejid) == 0)) {
+        if (by && g_strcmp0(by, from_jid->barejid) == 0 && _stanza_id_by_trusted(by)) {
             stanzaid = (char*)xmpp_stanza_get_attribute(stanzaidst, STANZA_ATTR_ID);
             if (stanzaid) {
                 message->stanzaid = strdup(stanzaid);
@@ -1397,7 +1398,7 @@ _handle_chat(xmpp_stanza_t* const stanza, gboolean is_mam, gboolean is_carbon, c
         xmpp_stanza_t* stanzaidst = xmpp_stanza_get_child_by_name_and_ns(stanza, STANZA_NAME_STANZA_ID, STANZA_NS_STABLE_ID);
         if (stanzaidst) {
             const char* by = xmpp_stanza_get_attribute(stanzaidst, "by");
-            if (by && equals_our_barejid(by)) {
+            if (by && equals_our_barejid(by) && _stanza_id_by_trusted(by)) {
                 stanzaid = (char*)xmpp_stanza_get_attribute(stanzaidst, STANZA_ATTR_ID);
                 if (stanzaid) {
                     message->stanzaid = strdup(stanzaid);
@@ -1735,3 +1736,22 @@ _should_ignore_based_on_silence(xmpp_stanza_t* const stanza)
     }
     return FALSE;
 }
+
+// XEP-0359 §6 disco-gate; falls back to domain since that's what disco is run against.
+static gboolean
+_stanza_id_by_trusted(const char* by)
+{
+    if (!by) {
+        return FALSE;
+    }
+    GHashTable* features = connection_get_features(by);
+    if (features && g_hash_table_contains(features, STANZA_NS_STABLE_ID)) {
+        return TRUE;
+    }
+    const char* at = strchr(by, '@');
+    if (!at) {
+        return FALSE;
+    }
+    features = connection_get_features(at + 1);
+    return features && g_hash_table_contains(features, STANZA_NS_STABLE_ID);
+}

tests/functionaltests/functionaltests.c

@@ -253,6 +253,10 @@ main(int argc, char* argv[])
         PROF_FUNC_TEST(message_receive_console),
         PROF_FUNC_TEST(message_receive_chatwin),
 
+        /* XEP-0359 disco gate for stanza-id trust */
+        PROF_FUNC_TEST(stanza_id_dedup_fires_when_server_announces_sid0),
+        PROF_FUNC_TEST(stanza_id_not_trusted_when_server_does_not_announce_sid0),
+
 #ifdef HAVE_SQLITE
         /* MUC (groupchat) database — export/import of type="muc" messages */
         PROF_FUNC_TEST(muc_export_sqlite_to_flatfile),

tests/functionaltests/test_message.c

@@ -56,3 +56,70 @@ message_receive_chatwin(void **state)
 
     assert_true(prof_output_regex("someuser@chatserv.org/laptop: .+How are you?"));
 }
+
+// XEP-0359 disco gate: server announces urn:xmpp:sid:0 -> stanza-id trusted -> replay flagged as duplicate.
+void
+stanza_id_dedup_fires_when_server_announces_sid0(void **state)
+{
+    stbbr_for_query("http://jabber.org/protocol/disco#info",
+        "<iq type='result' to='stabber@localhost/profanity' from='localhost'>"
+            "<query xmlns='http://jabber.org/protocol/disco#info'>"
+                "<identity category='server' type='im' name='TestServer'/>"
+                "<feature var='urn:xmpp:sid:0'/>"
+            "</query>"
+        "</iq>"
+    );
+
+    prof_connect();
+
+    stbbr_send(
+        "<message id='m-trust-1' to='stabber@localhost' from='someuser@chatserv.org/laptop' type='chat'>"
+            "<body>first</body>"
+            "<stanza-id xmlns='urn:xmpp:sid:0' by='stabber@localhost' id='archive-id-42'/>"
+        "</message>"
+    );
+    assert_true(prof_output_exact("<< chat message: someuser@chatserv.org/laptop (win 2)"));
+
+    stbbr_send(
+        "<message id='m-trust-2' to='stabber@localhost' from='someuser@chatserv.org/laptop' type='chat'>"
+            "<body>replay</body>"
+            "<stanza-id xmlns='urn:xmpp:sid:0' by='stabber@localhost' id='archive-id-42'/>"
+        "</message>"
+    );
+    assert_true(prof_output_exact("Got a message with duplicate (server-generated) stanza-id from someuser@chatserv.org/laptop."));
+}
+
+// XEP-0359 disco gate: server does NOT announce urn:xmpp:sid:0 -> stanza-id untrusted -> no replay error.
+void
+stanza_id_not_trusted_when_server_does_not_announce_sid0(void **state)
+{
+    stbbr_for_query("http://jabber.org/protocol/disco#info",
+        "<iq type='result' to='stabber@localhost/profanity' from='localhost'>"
+            "<query xmlns='http://jabber.org/protocol/disco#info'>"
+                "<identity category='server' type='im' name='TestServer'/>"
+                "<feature var='urn:xmpp:ping'/>"
+            "</query>"
+        "</iq>"
+    );
+
+    prof_connect();
+
+    stbbr_send(
+        "<message id='m-untrust-1' to='stabber@localhost' from='someuser@chatserv.org/laptop' type='chat'>"
+            "<body>first</body>"
+            "<stanza-id xmlns='urn:xmpp:sid:0' by='stabber@localhost' id='archive-id-77'/>"
+        "</message>"
+    );
+    assert_true(prof_output_exact("<< chat message: someuser@chatserv.org/laptop (win 2)"));
+
+    stbbr_send(
+        "<message id='m-untrust-2' to='stabber@localhost' from='someuser@chatserv.org/laptop' type='chat'>"
+            "<body>replay</body>"
+            "<stanza-id xmlns='urn:xmpp:sid:0' by='stabber@localhost' id='archive-id-77'/>"
+        "</message>"
+    );
+
+    prof_timeout(2);
+    assert_false(prof_output_exact("Got a message with duplicate (server-generated) stanza-id"));
+    prof_timeout_reset();
+}

tests/functionaltests/test_message.h

@@ -1,3 +1,5 @@
 void message_send(void **state);
 void message_receive_console(void **state);
 void message_receive_chatwin(void **state);
+void stanza_id_dedup_fires_when_server_announces_sid0(void **state);
+void stanza_id_not_trusted_when_server_does_not_announce_sid0(void **state);