[mojo-edk] Broadcast surprise port disruptions

mojo/edk/system/node_channel.cc

Index: mojo/edk/system/node_channel.cc
diff --git a/mojo/edk/system/node_channel.cc b/mojo/edk/system/node_channel.cc
index 885750d66786674d008f5f75e7b65d54a99240ca..22d97e266e9004491fcebe139a91a76d53a8eec7 100644
--- a/mojo/edk/system/node_channel.cc
+++ b/mojo/edk/system/node_channel.cc
@@ -39,6 +39,7 @@ enum class MessageType : uint32_t {
   REQUEST_PORT_MERGE,
   REQUEST_INTRODUCTION,
   INTRODUCE,
+  BROADCAST,
 #if defined(OS_WIN) || (defined(OS_MACOSX) && !defined(OS_IOS))
   RELAY_PORTS_MESSAGE,
 #endif
@@ -329,6 +330,15 @@ void NodeChannel::Introduce(const ports::NodeName& name,
   WriteChannelMessage(std::move(message));
 }
 
+void NodeChannel::Broadcast(Channel::MessagePtr message) {
+  DCHECK(!message->has_handles());
+  void* data;
+  Channel::MessagePtr broadcast_message = CreateMessage(
+      MessageType::BROADCAST, message->data_num_bytes(), 0, &data);
+  memcpy(data, message->data(), message->data_num_bytes());
+  WriteChannelMessage(std::move(broadcast_message));
+}
+
 #if defined(OS_WIN) || (defined(OS_MACOSX) && !defined(OS_IOS))
 void NodeChannel::RelayPortsMessage(const ports::NodeName& destination,
                                     Channel::MessagePtr message) {
@@ -574,6 +584,21 @@ void NodeChannel::OnChannelMessage(const void* payload,
       break;
     }
 
+    case MessageType::BROADCAST: {
+      if (payload_size <= sizeof(Header))
+        break;
+      const void* data = static_cast<const void*>(
+          reinterpret_cast<const Header*>(payload) + 1);
+      Channel::MessagePtr message =
+          Channel::Message::Deserialize(data, payload_size - sizeof(Header));
+      if (!message) {
+        DLOG(ERROR) << "Dropping invalid broadcast message.";
+        break;
+      }
+      delegate_->OnBroadcast(std::move(message));
+      return;
+    }
+
 #if defined(OS_WIN) || (defined(OS_MACOSX) && !defined(OS_IOS))
     case MessageType::RELAY_PORTS_MESSAGE: {
       base::ProcessHandle from_process;