Read all available CastMessages in CastSocket

This change makes CastSocket repeatedly deserialize CastMessages
whenever it gets a new block from TLS.  This fixes the case where
multiple messages are received in one TLS read.

Bug: 1050913
Change-Id: Ia29e2c82c29d921073eaa20874a835d33b2eb4bb
Reviewed-on: https://chromium-review.googlesource.com/c/openscreen/+/2151857
Commit-Queue: Brandon Tolsch <btolsch@chromium.org>
Reviewed-by: Ryan Keane <rwkeane@google.com>

2 files changed, 41 insertions, 9 deletions

diff --git a/cast/common/channel/cast_socket.cc b/cast/common/channel/cast_socket.cc
index 86880e23..070c4b53 100644
--- a/cast/common/channel/cast_socket.cc
+++ b/cast/common/channel/cast_socket.cc
@@ -71,15 +71,19 @@ void CastSocket::OnError(TlsConnection* connection, Error error) {
 
 void CastSocket::OnRead(TlsConnection* connection, std::vector<uint8_t> block) {
   read_buffer_.insert(read_buffer_.end(), block.begin(), block.end());
-  ErrorOr<DeserializeResult> message_or_error =
-      message_serialization::TryDeserialize(
-          absl::Span<uint8_t>(&read_buffer_[0], read_buffer_.size()));
-  if (!message_or_error) {
-    return;
-  }
-  read_buffer_.erase(read_buffer_.begin(),
-                     read_buffer_.begin() + message_or_error.value().length);
-  client_->OnMessage(this, std::move(message_or_error.value().message));
+  // NOTE: Read as many messages as possible out of |read_buffer_| since we only
+  // get one callback opportunity for this.
+  do {
+    ErrorOr<DeserializeResult> message_or_error =
+        message_serialization::TryDeserialize(
+            absl::Span<uint8_t>(&read_buffer_[0], read_buffer_.size()));
+    if (!message_or_error) {
+      return;
+    }
+    read_buffer_.erase(read_buffer_.begin(),
+                       read_buffer_.begin() + message_or_error.value().length);
+    client_->OnMessage(this, std::move(message_or_error.value().message));
+  } while (!read_buffer_.empty());
 }
 
 int CastSocket::g_next_socket_id_ = 1;
diff --git a/cast/common/channel/cast_socket_unittest.cc b/cast/common/channel/cast_socket_unittest.cc
index decfb041..351224fd 100644
--- a/cast/common/channel/cast_socket_unittest.cc
+++ b/cast/common/channel/cast_socket_unittest.cc
@@ -121,6 +121,34 @@ TEST_F(CastSocketTest, ReadChunkedMessage) {
                                            data + double_message.size()));
 }
 
+TEST_F(CastSocketTest, ReadMultipleMessagesPerBlock) {
+  CastMessage message2;
+  std::vector<uint8_t> frame_serial2;
+  message2.set_protocol_version(CastMessage::CASTV2_1_0);
+  message2.set_source_id("alt-source");
+  message2.set_destination_id("alt-destination");
+  message2.set_namespace_("alt-namespace");
+  message2.set_payload_type(CastMessage::STRING);
+  message2.set_payload_utf8("alternate payload");
+  ErrorOr<std::vector<uint8_t>> serialized_or_error =
+      message_serialization::Serialize(message2);
+  ASSERT_TRUE(serialized_or_error);
+  frame_serial2 = std::move(serialized_or_error.value());
+
+  std::vector<uint8_t> send_data;
+  send_data.reserve(frame_serial_.size() + frame_serial2.size());
+  send_data.insert(send_data.end(), frame_serial_.begin(), frame_serial_.end());
+  send_data.insert(send_data.end(), frame_serial2.begin(), frame_serial2.end());
+  EXPECT_CALL(mock_client(), OnMessage(_, _))
+      .WillOnce(Invoke([this](CastSocket* socket, CastMessage message) {
+        EXPECT_EQ(message_.SerializeAsString(), message.SerializeAsString());
+      }))
+      .WillOnce([message2](CastSocket* socket, CastMessage message) {
+        EXPECT_EQ(message2.SerializeAsString(), message.SerializeAsString());
+      });
+  connection().OnRead(std::move(send_data));
+}
+
 TEST_F(CastSocketTest, SanitizedAddress) {
   std::array<uint8_t, 2> result1 = socket().GetSanitizedIpAddress();
   EXPECT_EQ(result1[0], 1u);