fix(xmpp): handle disco#items error responses (XEP-0030 Section 7)

Refactor disco#items request handling to use id_handler pattern
(consistent with disco#info):

- Use dynamic stanza ID via connection_create_stanza_id()
- Register _disco_items_response_id_handler via iq_id_handler_add()
- Handle type='error' responses with cons_show_error()
- Split onconnect handler to use namespace-based routing separately

Previously, disco#items used a fixed stanza ID with namespace-based
routing, which could not intercept error responses (error stanzas
don't contain the query child element with the disco#items namespace).

Closes #91

src/xmpp/iq.c

@@ -129,6 +129,7 @@ static void _ping_get_handler(xmpp_stanza_t* const stanza);
 static int _version_result_id_handler(xmpp_stanza_t* const stanza, void* const userdata);
 static int _disco_info_response_id_handler(xmpp_stanza_t* const stanza, void* const userdata);
 static int _disco_info_response_id_handler_onconnect(xmpp_stanza_t* const stanza, void* const userdata);
+static int _disco_items_response_id_handler(xmpp_stanza_t* const stanza, void* const userdata);
 static int _http_upload_response_id_handler(xmpp_stanza_t* const stanza, void* const upload_ctx);
 static int _last_activity_response_id_handler(xmpp_stanza_t* const stanza, void* const userdata);
 static int _room_info_response_id_handler(xmpp_stanza_t* const stanza, void* const userdata);
@@ -203,7 +204,11 @@ _iq_handler(xmpp_conn_t* const conn, xmpp_stanza_t* const stanza, void* const us
         _disco_items_get_handler(stanza);
     }
     if (discoitems && (g_strcmp0(type, STANZA_TYPE_RESULT) == 0)) {
-        _disco_items_result_handler(stanza);
+        // Only handle onconnect here, user requests use id_handler
+        const char* id = xmpp_stanza_get_id(stanza);
+        if (g_strcmp0(id, "discoitemsreq_onconnect") == 0) {
+            _disco_items_result_handler(stanza);
+        }
     }
 
     xmpp_stanza_t* lastactivity = xmpp_stanza_get_child_by_ns(stanza, STANZA_NS_LASTACTIVITY);
@@ -637,7 +642,11 @@ void
 iq_disco_items_request(const char* jid)
 {
     xmpp_ctx_t* const ctx = connection_get_ctx();
-    xmpp_stanza_t* iq = stanza_create_disco_items_iq(ctx, "discoitemsreq", jid, NULL);
+    auto_char char* id = connection_create_stanza_id();
+    xmpp_stanza_t* iq = stanza_create_disco_items_iq(ctx, id, jid, NULL);
+
+    iq_id_handler_add(id, _disco_items_response_id_handler, NULL, NULL);
+
     iq_send_stanza(iq);
     xmpp_stanza_release(iq);
 }
@@ -2514,13 +2523,12 @@ _http_upload_response_id_handler(xmpp_stanza_t* const stanza, void* const userda
 static void
 _disco_items_result_handler(xmpp_stanza_t* const stanza)
 {
-    log_debug("Received disco#items response");
+    // This handler is only for onconnect disco#items requests
+    log_debug("Received disco#items response (onconnect)");
     const char* id = xmpp_stanza_get_id(stanza);
-    const char* from = xmpp_stanza_get_from(stanza);
     GSList* items = NULL;
 
-    if ((g_strcmp0(id, "discoitemsreq") != 0) && (g_strcmp0(id, "discoitemsreq_onconnect") != 0)) {
+    if (g_strcmp0(id, "discoitemsreq_onconnect") != 0) {
-        log_warning("_disco_items_result_handler: Received unexpected disco id: %s", id);
         return;
     }
 
@@ -2555,23 +2563,80 @@ _disco_items_result_handler(xmpp_stanza_t* const stanza)
         child = xmpp_stanza_get_next(child);
     }
 
-    if (g_strcmp0(id, "discoitemsreq") == 0) {
+    connection_set_disco_items(items);
-        cons_show_disco_items(items, from);
-    } else if (g_strcmp0(id, "discoitemsreq_onconnect") == 0) {
-        connection_set_disco_items(items);
 
-        while (late_delivery_windows) {
+    while (late_delivery_windows) {
-            LateDeliveryUserdata* del_data = late_delivery_windows->data;
+        LateDeliveryUserdata* del_data = late_delivery_windows->data;
-            _iq_mam_request(del_data->win, del_data->startdate, del_data->enddate);
+        _iq_mam_request(del_data->win, del_data->startdate, del_data->enddate);
-            free(del_data);
+        free(del_data);
-            late_delivery_windows = g_slist_delete_link(late_delivery_windows,
+        late_delivery_windows = g_slist_delete_link(late_delivery_windows,
-                                                        late_delivery_windows);
+                                                    late_delivery_windows);
-        }
     }
 
     g_slist_free_full(items, (GDestroyNotify)_item_destroy);
 }
 
+static int
+_disco_items_response_id_handler(xmpp_stanza_t* const stanza, void* const userdata)
+{
+    const char* from = xmpp_stanza_get_from(stanza);
+    const char* type = xmpp_stanza_get_type(stanza);
+
+    if (from) {
+        log_debug("Received disco#items response from: %s", from);
+    } else {
+        log_debug("Received disco#items response");
+    }
+
+    // Handle error responses
+    if (g_strcmp0(type, STANZA_TYPE_ERROR) == 0) {
+        auto_char char* error_message = stanza_get_error_message(stanza);
+        if (from) {
+            cons_show_error("Service discovery failed for %s: %s", from, error_message);
+        } else {
+            cons_show_error("Service discovery failed: %s", error_message);
+        }
+        return 0;
+    }
+
+    // Handle result responses
+    xmpp_stanza_t* query = xmpp_stanza_get_child_by_name(stanza, STANZA_NAME_QUERY);
+    if (query == NULL) {
+        cons_show_disco_items(NULL, from);
+        return 0;
+    }
+
+    GSList* items = NULL;
+    xmpp_stanza_t* child = xmpp_stanza_get_children(query);
+
+    while (child) {
+        const char* stanza_name = xmpp_stanza_get_name(child);
+        if (stanza_name && (g_strcmp0(stanza_name, STANZA_NAME_ITEM) == 0)) {
+            const char* item_jid = xmpp_stanza_get_attribute(child, STANZA_ATTR_JID);
+            if (item_jid) {
+                DiscoItem* item = malloc(sizeof(struct disco_item_t));
+                if (item) {
+                    item->jid = strdup(item_jid);
+                    const char* item_name = xmpp_stanza_get_attribute(child, STANZA_ATTR_NAME);
+                    if (item_name) {
+                        item->name = strdup(item_name);
+                    } else {
+                        item->name = NULL;
+                    }
+                    items = g_slist_append(items, item);
+                }
+            }
+        }
+
+        child = xmpp_stanza_get_next(child);
+    }
+
+    cons_show_disco_items(items, from);
+    g_slist_free_full(items, (GDestroyNotify)_item_destroy);
+
+    return 0;
+}
+
 void
 iq_feature_retrieval_complete_handler(void)
 {