remoting/protocol/message_reader.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef REMOTING_PROTOCOL_MESSAGE_READER_H_
#define REMOTING_PROTOCOL_MESSAGE_READER_H_

#include <memory>

#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "remoting/base/compound_buffer.h"
#include "remoting/protocol/message_decoder.h"

namespace net {
class IOBuffer;
}  // namespace net

namespace remoting::protocol {

class P2PStreamSocket;

// MessageReader reads data from the socket asynchronously and calls the
// callback for each message it receives. It stops calling the callback as soon
// as the socket is closed, so the socket should always be closed before the
// callback handler is destroyed.
//
// In order to throttle the stream, MessageReader doesn't try to read new data
// from the socket until all previously received messages are processed by the
// receiver (|done_task| is called for each message). It is still possible that
// the MessageReceivedCallback is called twice (so that there is more than one
// outstanding message), e.g. when we the sender sends multiple messages in one
// TCP packet.
class MessageReader {
 public:
  typedef base::RepeatingCallback<void(std::unique_ptr<CompoundBuffer> message)>
      MessageReceivedCallback;
  typedef base::OnceCallback<void(int)> ReadFailedCallback;

  MessageReader();

  MessageReader(const MessageReader&) = delete;
  MessageReader& operator=(const MessageReader&) = delete;

  virtual ~MessageReader();

  // Starts reading from |socket|.
  void StartReading(P2PStreamSocket* socket,
                    const MessageReceivedCallback& message_received_callback,
                    ReadFailedCallback read_failed_callback);

 private:
  void DoRead();
  void OnRead(int result);
  // Returns true on success, or runs |read_failed_callback_| and returns false
  // on failure. When false is returned, |this| may be deleted.
  bool HandleReadResult(int result);
  void OnDataReceived(net::IOBuffer* data, int data_size);
  void RunCallback(std::unique_ptr<CompoundBuffer> message);
  bool DidReadFail();

  ReadFailedCallback read_failed_callback_;

  raw_ptr<P2PStreamSocket> socket_ = nullptr;

  // Set to true, when we have a socket read pending, and expecting
  // OnRead() to be called when new data is received.
  bool read_pending_ = false;

  bool closed_ = false;
  scoped_refptr<net::IOBuffer> read_buffer_;

  MessageDecoder message_decoder_;

  // Callback is called when a message is received.
  MessageReceivedCallback message_received_callback_;

  SEQUENCE_CHECKER(sequence_checker_);

  base::WeakPtrFactory<MessageReader> weak_factory_{this};
};

}  // namespace remoting::protocol

#endif  // REMOTING_PROTOCOL_MESSAGE_READER_H_