Allow MessageFilters to restrict listening to specific message classes

ipc/ipc_channel_proxy.cc

Index: ipc/ipc_channel_proxy.cc
diff --git a/ipc/ipc_channel_proxy.cc b/ipc/ipc_channel_proxy.cc
index 3a0cf307b78e5fd2e35c57ba14de4cec6ed6d4f7..e0f394370458bd60b0eb4dfbe39276ad367d1967 100644
--- a/ipc/ipc_channel_proxy.cc
+++ b/ipc/ipc_channel_proxy.cc
@@ -17,6 +17,43 @@
 #include "ipc/ipc_message_utils.h"
 
 namespace IPC {
+namespace {
+
+bool ValidMessageClass(int message_class) {
+  return message_class > 0 && message_class < LastIPCMsgStart;

[piman, 2014/02/12 01:04:03]

0 is actually valid.

[jdduke (slow), 2014/02/12 02:12:39]

Ugg, good catch.

+}
+
+bool EraseFilter(const ChannelProxy::MessageFilter* filter,
+                 std::vector<ChannelProxy::MessageFilter*>& filters) {
+  std::vector<ChannelProxy::MessageFilter*>::iterator it =
+      std::find(filters.begin(), filters.end(), filter);
+  if (it == filters.end())
+    return false;
+
+  filters.erase(it);
+  return true;
+}
+
+bool ApplyFilters(std::vector<ChannelProxy::MessageFilter*>& filters,
+                  const IPC::Message& message,
+                  const std::string& channel_id) {
+#ifdef IPC_MESSAGE_LOG_ENABLED
+  Logging* logger = Logging::GetInstance();
+#endif
+
+  for (size_t i = 0; i < filters.size(); ++i) {
+    if (filters[i]->OnMessageReceived(message)) {
+#ifdef IPC_MESSAGE_LOG_ENABLED
+      if (logger->Enabled())
+        logger->OnPostDispatchMessage(message, channel_id);
+#endif
+      return true;
+    }
+  }
+  return false;
+}
+
+}  // namespace
 
 //------------------------------------------------------------------------------
 
@@ -36,6 +73,11 @@ bool ChannelProxy::MessageFilter::OnMessageReceived(const Message& message) {
   return false;
 }
 
+bool ChannelProxy::MessageFilter::GetSupportedMessageClasses(
+    std::vector<uint32>* /*supported_message_classes*/) const {
+  return false;
+}
+
 ChannelProxy::MessageFilter::~MessageFilter() {}
 
 //------------------------------------------------------------------------------
@@ -71,16 +113,18 @@ bool ChannelProxy::Context::TryFilters(const Message& message) {
     logger->OnPreDispatchMessage(message);
 #endif
 
-  for (size_t i = 0; i < filters_.size(); ++i) {
-    if (filters_[i]->OnMessageReceived(message)) {
-#ifdef IPC_MESSAGE_LOG_ENABLED
-      if (logger->Enabled())
-        logger->OnPostDispatchMessage(message, channel_id_);
-#endif
-      return true;
-    }
+  if (ApplyFilters(message_global_filters_, message, channel_id_))
+    return true;
+
+  const int message_class = IPC_MESSAGE_CLASS(message);
+  if (!ValidMessageClass(message_class)) {
+    NOTREACHED() << "Invalid message class: " << message_class;

[piman, 2014/02/12 01:04:03]

Not NOTREACHED. This could be reached in 2 cases:
- by a malicious renderer / nacl app.
- for message replies (class is 0xffff iirc).

Returning false is correct in either case.

[jdduke (slow), 2014/02/12 02:12:39]

Ahh, I hadn't considered replies, I'll make a slight assert distinction.

+    return false;
   }
-  return false;
+
+  return ApplyFilters(message_class_filters_[message_class],
+                      message,
+                      channel_id_);
 }
 
 // Called on the IPC::Channel thread
@@ -108,8 +152,8 @@ void ChannelProxy::Context::OnChannelConnected(int32 peer_pid) {
 
   // We cache off the peer_pid so it can be safely accessed from both threads.
   peer_pid_ = channel_->peer_pid();
-  for (size_t i = 0; i < filters_.size(); ++i)
-    filters_[i]->OnChannelConnected(peer_pid);
+  for (size_t i = 0; i < all_filters_.size(); ++i)
+    all_filters_[i]->OnChannelConnected(peer_pid);
 
   // See above comment about using listener_task_runner_ here.
   listener_task_runner_->PostTask(
@@ -118,8 +162,8 @@ void ChannelProxy::Context::OnChannelConnected(int32 peer_pid) {
 
 // Called on the IPC::Channel thread
 void ChannelProxy::Context::OnChannelError() {
-  for (size_t i = 0; i < filters_.size(); ++i)
-    filters_[i]->OnChannelError();
+  for (size_t i = 0; i < all_filters_.size(); ++i)
+    all_filters_[i]->OnChannelError();
 
   // See above comment about using listener_task_runner_ here.
   listener_task_runner_->PostTask(
@@ -139,8 +183,8 @@ void ChannelProxy::Context::OnChannelOpened() {
     return;
   }
 
-  for (size_t i = 0; i < filters_.size(); ++i)
-    filters_[i]->OnFilterAdded(channel_.get());
+  for (size_t i = 0; i < all_filters_.size(); ++i)
+    all_filters_[i]->OnFilterAdded(channel_.get());
 }
 
 // Called on the IPC::Channel thread
@@ -150,13 +194,16 @@ void ChannelProxy::Context::OnChannelClosed() {
   if (!channel_.get())
     return;
 
-  for (size_t i = 0; i < filters_.size(); ++i) {
-    filters_[i]->OnChannelClosing();
-    filters_[i]->OnFilterRemoved();
+  for (size_t i = 0; i < all_filters_.size(); ++i) {
+    all_filters_[i]->OnChannelClosing();
+    all_filters_[i]->OnFilterRemoved();
   }
 
   // We don't need the filters anymore.
-  filters_.clear();
+  all_filters_.clear();
+  message_global_filters_.clear();
+  for (size_t i = 0; i < LastIPCMsgStart; ++i)
+    message_class_filters_[i].clear();
 
   channel_.reset();
 
@@ -187,16 +234,31 @@ void ChannelProxy::Context::OnAddFilter() {
     new_filters.swap(pending_filters_);
   }
 
+  std::vector<uint32> supported_message_classes;
   for (size_t i = 0; i < new_filters.size(); ++i) {
-    filters_.push_back(new_filters[i]);
+    all_filters_.push_back(new_filters[i]);
+
+    // Determine if the filter should be applied to all messages, or only
+    // messages of a certain class.
+    MessageFilter* filter = new_filters[i].get();
+    if (filter->GetSupportedMessageClasses(&supported_message_classes)) {
+      DCHECK(!supported_message_classes.empty());
+      for (size_t i = 0; i < supported_message_classes.size(); ++i) {
+        DCHECK(ValidMessageClass(supported_message_classes[i]));
+        message_class_filters_[supported_message_classes[i]].push_back(filter);
+      }
+    } else {
+      message_global_filters_.push_back(filter);
+    }
+    supported_message_classes.clear();
 
     // If the channel has already been created, then we need to send this
     // message so that the filter gets access to the Channel.
     if (channel_.get())
-      new_filters[i]->OnFilterAdded(channel_.get());
+      filter->OnFilterAdded(channel_.get());
     // Ditto for if the channel has been connected.
     if (peer_pid_)
-      new_filters[i]->OnChannelConnected(peer_pid_);
+      filter->OnChannelConnected(peer_pid_);
   }
 }
 
@@ -205,15 +267,26 @@ void ChannelProxy::Context::OnRemoveFilter(MessageFilter* filter) {
   if (!channel_.get())
     return;  // The filters have already been deleted.
 
-  for (size_t i = 0; i < filters_.size(); ++i) {
-    if (filters_[i].get() == filter) {
+  bool filter_exists = false;
+  for (size_t i = 0; i < all_filters_.size(); ++i) {
+    if (all_filters_[i].get() == filter) {
       filter->OnFilterRemoved();
-      filters_.erase(filters_.begin() + i);
-      return;
+      all_filters_.erase(all_filters_.begin() + i);
+      filter_exists = true;
+      break;
     }
   }
 
-  NOTREACHED() << "filter to be removed not found";
+  if (!filter_exists) {
+    NOTREACHED() << "filter to be removed not found";
+    return;
+  }
+
+  if (EraseFilter(filter, message_global_filters_))
+    return;
+
+  for (size_t i = 0; i < LastIPCMsgStart; ++i)
+    EraseFilter(filter, message_class_filters_[i]);
 }
 
 // Called on the listener's thread