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      1 /*
      2  * libjingle
      3  * Copyright 2004--2005, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef TALK_P2P_BASE_PSEUDOTCP_H_
     29 #define TALK_P2P_BASE_PSEUDOTCP_H_
     30 
     31 #include <list>
     32 
     33 #include "talk/base/basictypes.h"
     34 
     35 namespace cricket {
     36 
     37 //////////////////////////////////////////////////////////////////////
     38 // IPseudoTcpNotify
     39 //////////////////////////////////////////////////////////////////////
     40 
     41 class PseudoTcp;
     42 
     43 class IPseudoTcpNotify {
     44  public:
     45   virtual ~IPseudoTcpNotify() {}
     46   // Notification of tcp events
     47   virtual void OnTcpOpen(PseudoTcp* tcp) = 0;
     48   virtual void OnTcpReadable(PseudoTcp* tcp) = 0;
     49   virtual void OnTcpWriteable(PseudoTcp* tcp) = 0;
     50   virtual void OnTcpClosed(PseudoTcp* tcp, uint32 error) = 0;
     51 
     52   // Write the packet onto the network
     53   enum WriteResult { WR_SUCCESS, WR_TOO_LARGE, WR_FAIL };
     54   virtual WriteResult TcpWritePacket(PseudoTcp* tcp,
     55                                      const char* buffer, size_t len) = 0;
     56 };
     57 
     58 //////////////////////////////////////////////////////////////////////
     59 // PseudoTcp
     60 //////////////////////////////////////////////////////////////////////
     61 
     62 class PseudoTcp {
     63  public:
     64   static uint32 Now();
     65 
     66   PseudoTcp(IPseudoTcpNotify* notify, uint32 conv);
     67   virtual ~PseudoTcp();
     68 
     69   int Connect();
     70   int Recv(char* buffer, size_t len);
     71   int Send(const char* buffer, size_t len);
     72   void Close(bool force);
     73   int GetError();
     74 
     75   enum TcpState {
     76     TCP_LISTEN, TCP_SYN_SENT, TCP_SYN_RECEIVED, TCP_ESTABLISHED, TCP_CLOSED
     77   };
     78   TcpState State() const { return m_state; }
     79 
     80   // Call this when the PMTU changes.
     81   void NotifyMTU(uint16 mtu);
     82 
     83   // Call this based on timeout value returned from GetNextClock.
     84   // It's ok to call this too frequently.
     85   void NotifyClock(uint32 now);
     86 
     87   // Call this whenever a packet arrives.
     88   // Returns true if the packet was processed successfully.
     89   bool NotifyPacket(const char * buffer, size_t len);
     90 
     91   // Call this to determine the next time NotifyClock should be called.
     92   // Returns false if the socket is ready to be destroyed.
     93   bool GetNextClock(uint32 now, long& timeout);
     94 
     95   // Call these to get/set option values to tailor this PseudoTcp
     96   // instance's behaviour for the kind of data it will carry.
     97   // If an unrecognized option is set or got, an assertion will fire.
     98   enum Option {
     99     OPT_NODELAY,      // Whether to enable Nagle's algorithm (0 == off)
    100     OPT_ACKDELAY,     // The Delayed ACK timeout (0 == off).
    101     //kOptRcvBuf,     // Set the receive buffer size, in bytes.
    102     //kOptSndBuf,     // Set the send buffer size, in bytes.
    103   };
    104   void GetOption(Option opt, int* value);
    105   void SetOption(Option opt, int value);
    106 
    107  protected:
    108   enum SendFlags { sfNone, sfDelayedAck, sfImmediateAck };
    109   enum {
    110     // Note: can't go as high as 1024 * 64, because of uint16 precision
    111     kRcvBufSize = 1024 * 60,
    112     // Note: send buffer should be larger to make sure we can always fill the
    113     // receiver window
    114     kSndBufSize = 1024 * 90
    115   };
    116 
    117   struct Segment {
    118     uint32 conv, seq, ack;
    119     uint8 flags;
    120     uint16 wnd;
    121     const char * data;
    122     uint32 len;
    123     uint32 tsval, tsecr;
    124   };
    125 
    126   struct SSegment {
    127     SSegment(uint32 s, uint32 l, bool c)
    128         : seq(s), len(l), /*tstamp(0),*/ xmit(0), bCtrl(c) {
    129     }
    130     uint32 seq, len;
    131     //uint32 tstamp;
    132     uint8 xmit;
    133     bool bCtrl;
    134   };
    135   typedef std::list<SSegment> SList;
    136 
    137   struct RSegment {
    138     uint32 seq, len;
    139   };
    140 
    141   uint32 queue(const char* data, uint32 len, bool bCtrl);
    142 
    143   IPseudoTcpNotify::WriteResult packet(uint32 seq, uint8 flags,
    144                                        const char* data, uint32 len);
    145   bool parse(const uint8* buffer, uint32 size);
    146 
    147   void attemptSend(SendFlags sflags = sfNone);
    148 
    149   void closedown(uint32 err = 0);
    150 
    151   bool clock_check(uint32 now, long& nTimeout);
    152 
    153   bool process(Segment& seg);
    154   bool transmit(const SList::iterator& seg, uint32 now);
    155 
    156   void adjustMTU();
    157 
    158  private:
    159   IPseudoTcpNotify* m_notify;
    160   enum Shutdown { SD_NONE, SD_GRACEFUL, SD_FORCEFUL } m_shutdown;
    161   int m_error;
    162 
    163   // TCB data
    164   TcpState m_state;
    165   uint32 m_conv;
    166   bool m_bReadEnable, m_bWriteEnable, m_bOutgoing;
    167   uint32 m_lasttraffic;
    168 
    169   // Incoming data
    170   typedef std::list<RSegment> RList;
    171   RList m_rlist;
    172   char m_rbuf[kRcvBufSize];
    173   uint32 m_rcv_nxt, m_rcv_wnd, m_rlen, m_lastrecv;
    174 
    175   // Outgoing data
    176   SList m_slist;
    177   char m_sbuf[kSndBufSize];
    178   uint32 m_snd_nxt, m_snd_wnd, m_slen, m_lastsend, m_snd_una;
    179   // Maximum segment size, estimated protocol level, largest segment sent
    180   uint32 m_mss, m_msslevel, m_largest, m_mtu_advise;
    181   // Retransmit timer
    182   uint32 m_rto_base;
    183 
    184   // Timestamp tracking
    185   uint32 m_ts_recent, m_ts_lastack;
    186 
    187   // Round-trip calculation
    188   uint32 m_rx_rttvar, m_rx_srtt, m_rx_rto;
    189 
    190   // Congestion avoidance, Fast retransmit/recovery, Delayed ACKs
    191   uint32 m_ssthresh, m_cwnd;
    192   uint8 m_dup_acks;
    193   uint32 m_recover;
    194   uint32 m_t_ack;
    195 
    196   // Configuration options
    197   bool m_use_nagling;
    198   uint32 m_ack_delay;
    199 };
    200 
    201 }  // namespace cricket
    202 
    203 #endif  // TALK_P2P_BASE_PSEUDOTCP_H_
    204