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..d0cb7b6a71e1d55ffc54386ed78340449977c71c 100644
--- a/chrome/browser/extensions/api/mdns/mdns_api.cc
+++ b/chrome/browser/extensions/api/mdns/mdns_api.cc
@@ -9,7 +9,11 @@
 #include "base/lazy_instance.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/common/extensions/api/mdns.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/render_view_host.h"
+#include "extensions/browser/extension_host.h"
 #include "extensions/browser/extension_registry.h"
+#include "extensions/common/extension_messages.h"
 
 namespace extensions {
 
@@ -140,6 +144,17 @@ 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 (static_cast<long>(args.size()) ==
+        api::mdns::MAX_SERVICE_INSTANCES_PER_EVENT) {
+      std::string msg(base::StringPrintf(
+          "Truncating service instances in onServiceList event to max: %d",
+          api::mdns::MAX_SERVICE_INSTANCES_PER_EVENT));
+      WriteToConsole(service_type,
+                     content::CONSOLE_MESSAGE_LEVEL_WARNING,
+                     msg);
+      VLOG(logging::LOG_WARNING) << msg;
+      break;
+    }
     linked_ptr<mdns::MDnsService> mdns_service =
         make_linked_ptr(new mdns::MDnsService);
     mdns_service->service_name = (*it).service_name;
@@ -162,4 +177,53 @@ void MDnsAPI::OnDnsSdEvent(const std::string& service_type,
   extensions::EventRouter::Get(browser_context_)->BroadcastEvent(event.Pass());
 }
 
+void MDnsAPI::WriteToConsole(const std::string& service_type,
+                             content::ConsoleMessageLevel level,
+                             const std::string& message) {
+  std::set<std::string> extension_ids;
+
+  // Check all listeners for service type filters.

[not at google - send to devlin, 2015/04/03 20:36:00]

Much of this code does look very similar to what's already in
UpdateMDnsListeners, can you unify it somehow?

[Red Daly, 2015/04/03 21:12:22]

Done.

+  for (const auto& listener :
+           extensions::EventRouter::Get(browser_context_)->listeners()
+           .GetEventListenersByName(mdns::OnServiceList::kEventName)) {
+    base::DictionaryValue* filter = (listener->filter());
+
+    std::string filter_value;
+    filter->GetStringASCII(kEventFilterServiceTypeKey, &filter_value);
+    if (filter_value.empty())
+      continue;
+
+    const Extension* extension = ExtensionRegistry::Get(browser_context_)->
+        enabled_extensions().GetByID(listener->extension_id());
+    // Don't listen for services associated only with disabled extensions.
+    if (!extension)
+      continue;
+
+    // Platform apps may query for all services; other types of extensions are
+    // restricted to a whitelist.
+    if (!extension->is_platform_app() &&
+        !IsServiceTypeWhitelisted(filter_value))
+      continue;
+
+    extension_ids.insert(listener->extension_id());
+  }
+
+  // Log to the consoles of the background pages of relevant listeners.
+  for (const std::string& extension_id : extension_ids) {
+    extensions::ExtensionHost* host =
+        extensions::ProcessManager::Get(browser_context_)
+        ->GetBackgroundHostForExtension(extension_id);
+    if (!host)
+      continue;
+    content::RenderProcessHost* rph = host->render_process_host();
+    content::RenderViewHost* rvh = host->render_view_host();
+    if (!rvh || !rph)
+      continue;
+    rph->Send(new ExtensionMsg_AddMessageToConsole(
+        rvh->GetRoutingID(),

[not at google - send to devlin, 2015/04/03 20:35:59]

You should be able to send directly to the RenderViewHost, no need to fetch the
RenderProcessHost.

[Red Daly, 2015/04/03 21:12:22]

Done.

+        level,
+        message));
+  }
+}
+
 }  // namespace extensions