Update the mDNS native extension for Mac OS to handle PTR and SRV records

src/pkg/mdns/mdns_extension.cc

 // Copyright (c) 2015, the Fletch project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE.md file.
 
 #include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 
 #include "mdns_extension.h"
 
 // Handle request send on the service port.
 void HandleRequest(Dart_Port port_id, Dart_CObject* message) {
   // Messages are expected to be three item lists:
   //  [0]: reply port
   //  [1]: request type
   //  [2]: request argument
   if (message->type == Dart_CObject_kArray &&
-      message->value.as_array.length == 3) {
+      message->value.as_array.length > 2) {
     Dart_CObject* reply_port = message->value.as_array.values[0];
     Dart_CObject* request_type = message->value.as_array.values[1];
-    Dart_CObject* argument = message->value.as_array.values[2];
-    if (reply_port->type == Dart_CObject_kSendPort) {
-      if (request_type->type == Dart_CObject_kInt32) {
-        switch (request_type->value.as_int32) {
-          case kEchoRequest:
+    if (reply_port->type == Dart_CObject_kSendPort &&
+        request_type->type == Dart_CObject_kInt32) {
+      switch (request_type->value.as_int32) {
+        case kEchoRequest:
+          if (message->value.as_array.length == 3) {
+            Dart_CObject* argument = message->value.as_array.values[2];
             HandleEcho(reply_port->value.as_send_port.id, argument);
             return;
+          }
 
-          case kLookupRequest:
-            HandleLookup(reply_port->value.as_send_port.id,
-                         argument->value.as_string);
+        case kLookupRequest:
+          if (message->value.as_array.length == 4) {
+            Dart_CObject* type = message->value.as_array.values[2];
+            Dart_CObject* name = message->value.as_array.values[3];
+            if (type->type == Dart_CObject_kInt32 &&
+                name->type == Dart_CObject_kString) {
+              HandleLookup(reply_port->value.as_send_port.id,
+                           type->value.as_int32,
+                           name->value.as_string);
+            }
             return;
+          }
 
-          default:
-            break;
-            // Ignore invalid requests.
-        }
+        default:
+          break;
+          // Ignore invalid requests.
       }
-      Dart_CObject result;
-      result.type = Dart_CObject_kNull;
-      Dart_PostCObject(reply_port->value.as_send_port.id, &result);
     }
+    Dart_CObject result;
+    result.type = Dart_CObject_kNull;
+    Dart_PostCObject(reply_port->value.as_send_port.id, &result);
   }
 }
 
 // Handler for the echo request. Used for testing that the native extension
 // can be loaded and called.
 void HandleEcho(Dart_Port reply_port, Dart_CObject* argument) {
   Dart_PostCObject(reply_port, argument);
 }
 
 
@@ skipping 40 matching lines @@
     return parent_library;
   }
 
   result_code = Dart_SetNativeResolver(parent_library, ResolveName, NULL);
   if (Dart_IsError(result_code)) {
     return result_code;
   }
 
   return parent_library;
 }