fix(mdns): Fix zero-sized VLA clang-tidy warnings

and some minor leaks in creation of browse results

Author: david-cermak

components/mdns/mdns.c

@@ -2355,6 +2355,11 @@ static void _mdns_restart_pcb(mdns_if_t tcpip_if, mdns_ip_protocol_t ip_protocol
         srv_count++;
         a = a->next;
     }
+    if (srv_count == 0) {
+        // proble only IP
+        _mdns_init_pcb_probe(tcpip_if, ip_protocol, NULL, 0, true);
+        return;
+    }
     mdns_srv_item_t *services[srv_count];
     size_t i = 0;
     a = _mdns_server->services;
@@ -2555,6 +2560,10 @@ static void _mdns_restart_all_pcbs(void)
         srv_count++;
         a = a->next;
     }
+    if (srv_count == 0) {
+        _mdns_probe_all_pcbs(NULL, 0, true, true);
+        return;
+    }
     mdns_srv_item_t *services[srv_count];
     size_t l = 0;
     a = _mdns_server->services;
@@ -2898,11 +2907,12 @@ static int _mdns_check_srv_collision(mdns_service_t *service, uint16_t priority,
 static int _mdns_check_txt_collision(mdns_service_t *service, const uint8_t *data, size_t len)
 {
     size_t data_len = 0;
-    if (len == 1 && service->txt) {
+    if (len <= 1 && service->txt) {     // len==0 means incorrect packet (and handled by the packet parser)
+        // but handled here again to fix clang-tidy warning on VLA "uint8_t our[0];"
         return -1;//we win
     } else if (len > 1 && !service->txt) {
         return 1;//they win
-    } else if (len == 1 && !service->txt) {
+    } else if (len <= 1 && !service->txt) {
         return 0;//same
     }
 
@@ -3788,7 +3798,7 @@ void mdns_parse_packet(mdns_rx_packet_t *packet)
             mdns_class &= 0x7FFF;
 
             content = data_ptr + data_len;
-            if (content > (data + len)) {
+            if (content > (data + len) || data_len == 0) {
                 goto clear_rx_packet;
             }
 
@@ -4271,15 +4281,10 @@ void mdns_parse_packet(mdns_rx_packet_t *packet)
         free(record);
     }
     free(parsed_packet);
-    if (browse_result_instance) {
-        free(browse_result_instance);
-    }
-    if (browse_result_service) {
-        free(browse_result_service);
-    }
-    if (browse_result_proto) {
-        free(browse_result_proto);
-    }
+    free(browse_result_instance);
+    free(browse_result_service);
+    free(browse_result_proto);
+    free(out_sync_browse);
 }
 
 /**