Limit number of service instances passed to onServiceList listeners.

chrome/browser/extensions/api/mdns/mdns_api.cc

Index: chrome/browser/extensions/api/mdns/mdns_api.cc
diff --git a/chrome/browser/extensions/api/mdns/mdns_api.cc b/chrome/browser/extensions/api/mdns/mdns_api.cc
index 2a7c41d210931d1540e61b8cb89fe402a203e1e8..7111a6207eedd64a65b80859816fc6567e8763f2 100644
--- a/chrome/browser/extensions/api/mdns/mdns_api.cc
+++ b/chrome/browser/extensions/api/mdns/mdns_api.cc
@@ -22,6 +22,10 @@ const char kCastServiceType[] = "_googlecast._tcp.local";
 const char kPrivetServiceType[] = "_privet._tcp.local";
 const char kTestServiceType[] = "_testing._tcp.local";
 
+// Maximum number of services that may be included in an onServiceList event
+// as arguments.
+const uint8 kMaxServicesPerOnServiceListEvent = 64;
+
 bool IsServiceTypeWhitelisted(const std::string& service_type) {
   return service_type == kCastServiceType ||
          service_type == kPrivetServiceType ||
@@ -140,6 +144,13 @@ void MDnsAPI::OnDnsSdEvent(const std::string& service_type,
   std::vector<linked_ptr<mdns::MDnsService> > args;
   for (DnsSdRegistry::DnsSdServiceList::const_iterator it = services.begin();
        it != services.end(); ++it) {
+    if (args.size() == kMaxServicesPerOnServiceListEvent) {
+      VLOG(logging::LOG_WARNING)
+          << "Truncating service instances reported in onServiceList event to "
+          << "max: "
+          << kMaxServicesPerOnServiceListEvent;
+      break;
+    }
     linked_ptr<mdns::MDnsService> mdns_service =
         make_linked_ptr(new mdns::MDnsService);
     mdns_service->service_name = (*it).service_name;
@@ -162,4 +173,10 @@ void MDnsAPI::OnDnsSdEvent(const std::string& service_type,
   extensions::EventRouter::Get(browser_context_)->BroadcastEvent(event.Pass());
 }
 
+ExtensionFunction::ResponseAction
+MdnsGetMaxServiceInstancesPerEventFunction::Run() {
+  return RespondNow(OneArgument(new base::FundamentalValue(
+      kMaxServicesPerOnServiceListEvent)));
+}
+
 }  // namespace extensions