text: // Copyright 2014 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef MEDIA_CAST_NET_UDP_TRANSPORT_H_
  #define MEDIA_CAST_NET_UDP_TRANSPORT_H_
  
  #include <stdint.h>
  
  #include <memory>
  
  #include "base/macros.h"
  #include "base/memory/ref_counted.h"
  #include "base/memory/weak_ptr.h"
  #include "base/values.h"
  #include "build/build_config.h"
  #include "media/cast/cast_environment.h"
  #include "media/cast/net/cast_transport.h"
  #include "media/cast/net/cast_transport_config.h"
  #include "media/cast/net/pacing/paced_sender.h"
  #include "net/base/io_buffer.h"
  #include "net/base/ip_endpoint.h"
  #include "net/udp/diff_serv_code_point.h"
  #include "net/udp/udp_socket.h"
  
  namespace net {
  class NetLog;
  }  // namespace net
  
  namespace media {
  namespace cast {
  
  // This class implements UDP transport mechanism for Cast.
  class UdpTransport : public PacketTransport {
   public:
    // Construct a UDP transport.
    // All methods must be called on |io_thread_proxy|.
    // |local_end_point| specifies the address and port to bind and listen
    // to incoming packets. If the value is 0.0.0.0:0 then a bind is not
    // performed.
    // |remote_end_point| specifies the address and port to send packets
    // to. If the value is 0.0.0.0:0 the the end point is set to the source
    // address of the first packet received.
    // |send_buffer_size| specifies the size of the socket send buffer.
    UdpTransport(
        net::NetLog* net_log,
        const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_proxy,
        const net::IPEndPoint& local_end_point,
        const net::IPEndPoint& remote_end_point,
        const CastTransportStatusCallback& status_callback);
    ~UdpTransport() final;
  
    // Start receiving packets. Packets are submitted to |packet_receiver|.
    void StartReceiving(
        const PacketReceiverCallbackWithStatus& packet_receiver) final;
    void StopReceiving() final;
  
    // Set a new DSCP value to the socket. The value will be set right before
    // the next send.
    void SetDscp(net::DiffServCodePoint dscp);
  
    // Set UdpTransport options.
    // Possible keys are:
    //   "pacer_max_burst_size": int
    //        - Specifies how many pakcets to send per 10 ms, maximum.
    //   "send_buffer_min_size": int
    //        - Specifies the minimum socket send buffer size.
    //   "DSCP" (value ignored)
    //       - Turns DSCP on (higher IP Precedence and Type of Service).
    //   "disable_non_blocking_io" (value ignored)
    //       - Windows only.  Turns off non-blocking IO for the socket.
    //         Note: Non-blocking IO is, by default, enabled on all platforms.
    void SetUdpOptions(const base::DictionaryValue& options);
  
    // This has to be called before |StartReceiving()| to change the
    // |send_buffer_size_|. Calling |SetUdpOptions()| will automatically call it.
    void SetSendBufferSize(int32_t send_buffer_size);
  
  #if defined(OS_WIN)
    // Switch to use non-blocking IO. Must be called before StartReceiving().
    void UseNonBlockingIO();
  #endif
  
    // PacketTransport implementations.
    bool SendPacket(PacketRef packet, const base::Closure& cb) final;
    int64_t GetBytesSent() final;
  
   private:
    // Requests and processes packets from |udp_socket_|.  This method is called
    // once with |length_or_status| set to net::ERR_IO_PENDING to start receiving
    // packets.  Thereafter, it is called with some other value as the callback
    // response from UdpSocket::RecvFrom().
    void ReceiveNextPacket(int length_or_status);
  
    // Schedule packet receiving, if needed.
    void ScheduleReceiveNextPacket();
  
    void OnSent(const scoped_refptr<net::IOBuffer>& buf,
                PacketRef packet,
                const base::Closure& cb,
                int result);
  
    const scoped_refptr<base::SingleThreadTaskRunner> io_thread_proxy_;
    const net::IPEndPoint local_addr_;
    net::IPEndPoint remote_addr_;
    std::unique_ptr<net::UDPSocket> udp_socket_;
    bool send_pending_;
    bool receive_pending_;
    bool client_connected_;
    net::DiffServCodePoint next_dscp_value_;
    std::unique_ptr<Packet> next_packet_;
    scoped_refptr<net::WrappedIOBuffer> recv_buf_;
    net::IPEndPoint recv_addr_;
    PacketReceiverCallbackWithStatus packet_receiver_;
    int32_t send_buffer_size_;
    const CastTransportStatusCallback status_callback_;
    int bytes_sent_;
  
    // NOTE: Weak pointers must be invalidated before all other member variables.
    base::WeakPtrFactory<UdpTransport> weak_factory_;
  
    DISALLOW_COPY_AND_ASSIGN(UdpTransport);
  };
  
  }  // namespace cast
  }  // namespace media
  
  #endif  // MEDIA_CAST_NET_UDP_TRANSPORT_H_
  