pseudotcp.cc

本人收集整理的一份c/c++跨平台网络库

/*
 * libjingle
 * Copyright 2004--2005, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice, 
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products 
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "talk/base/basicdefs.h"
#include "talk/base/basictypes.h"
#include "talk/base/byteorder.h"
#include "talk/base/common.h"
#include "talk/base/logging.h"
#include "talk/base/socket.h"
#include "talk/base/stringutils.h"
#include "talk/base/time.h"
#include "talk/p2p/base/pseudotcp.h"

#ifdef POSIX
extern "C" {
#include <errno.h>
}
#endif // POSIX

// The following logging is for detailed (packet-level) pseudotcp analysis only.
#define _DBG_NONE     0
#define _DBG_NORMAL   1
#define _DBG_VERBOSE  2
#define _DEBUGMSG _DBG_NONE

namespace cricket {

//////////////////////////////////////////////////////////////////////
// Network Constants
//////////////////////////////////////////////////////////////////////

// Standard MTUs
const uint16 PACKET_MAXIMUMS[] = {
  65535,    // Theoretical maximum, Hyperchannel
  32000,    // Nothing
  17914,    // 16Mb IBM Token Ring
  8166,   // IEEE 802.4
  //4464,   // IEEE 802.5 (4Mb max)
  4352,   // FDDI
  //2048,   // Wideband Network
  2002,   // IEEE 802.5 (4Mb recommended)
  //1536,   // Expermental Ethernet Networks
  //1500,   // Ethernet, Point-to-Point (default)
  1492,   // IEEE 802.3
  1006,   // SLIP, ARPANET
  //576,    // X.25 Networks
  //544,    // DEC IP Portal
  //512,    // NETBIOS
  508,    // IEEE 802/Source-Rt Bridge, ARCNET
  296,    // Point-to-Point (low delay)
  //68,     // Official minimum
  0,      // End of list marker
};

const uint32 MAX_PACKET = 65535;
// Note: we removed lowest level because packet overhead was larger!
const uint32 MIN_PACKET = 296;

const uint32 IP_HEADER_SIZE = 20; // (+ up to 40 bytes of options?)
const uint32 ICMP_HEADER_SIZE = 8;
const uint32 UDP_HEADER_SIZE = 8;
// TODO: Make JINGLE_HEADER_SIZE transparent to this code?
const uint32 JINGLE_HEADER_SIZE = 64; // when relay framing is in use

//////////////////////////////////////////////////////////////////////
// Global Constants and Functions
//////////////////////////////////////////////////////////////////////
//
//    0                   1                   2                   3   
//    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  0 |                      Conversation Number                      |
//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  4 |                        Sequence Number                        |
//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//  8 |                     Acknowledgment Number                     |
//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//    |               |   |U|A|P|R|S|F|                               |
// 12 |    Control    |   |R|C|S|S|Y|I|            Window             |
//    |               |   |G|K|H|T|N|N|                               |
//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// 16 |                       Timestamp sending                       |
//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// 20 |                      Timestamp receiving                      |
//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// 24 |                             data                              |
//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
//
//////////////////////////////////////////////////////////////////////

#define PSEUDO_KEEPALIVE 0

const uint32 MAX_SEQ = 0xFFFFFFFF;
const uint32 HEADER_SIZE = 24;
const uint32 PACKET_OVERHEAD = HEADER_SIZE + UDP_HEADER_SIZE + IP_HEADER_SIZE + JINGLE_HEADER_SIZE;

const uint32 MIN_RTO   =   250; // 250 ms (RFC1122, Sec 4.2.3.1 "fractions of a second")
const uint32 DEF_RTO   =  3000; // 3 seconds (RFC1122, Sec 4.2.3.1)
const uint32 MAX_RTO   = 60000; // 60 seconds
const uint32 ACK_DELAY =   100; // 100 milliseconds

const uint8 FLAG_CTL = 0x02;
const uint8 FLAG_RST = 0x04;

const uint8 CTL_CONNECT = 0;
//const uint8 CTL_REDIRECT = 1;
const uint8 CTL_EXTRA = 255;

/*
const uint8 FLAG_FIN = 0x01;
const uint8 FLAG_SYN = 0x02;
const uint8 FLAG_ACK = 0x10;
*/

const uint32 CTRL_BOUND = 0x80000000;

const long DEFAULT_TIMEOUT = 4000; // If there are no pending clocks, wake up every 4 seconds
const long CLOSED_TIMEOUT = 60 * 1000; // If the connection is closed, once per minute

#if PSEUDO_KEEPALIVE
// !?! Rethink these times
const uint32 IDLE_PING = 20 * 1000; // 20 seconds (note: WinXP SP2 firewall udp timeout is 90 seconds)
const uint32 IDLE_TIMEOUT = 90 * 1000; // 90 seconds;
#endif // PSEUDO_KEEPALIVE

//////////////////////////////////////////////////////////////////////
// Helper Functions
//////////////////////////////////////////////////////////////////////

inline void long_to_bytes(uint32 val, void* buf) {
  *static_cast<uint32*>(buf) = talk_base::HostToNetwork32(val);
}

inline void short_to_bytes(uint16 val, void* buf) {
  *static_cast<uint16*>(buf) = talk_base::HostToNetwork16(val);
}

inline uint32 bytes_to_long(const void* buf) {
  return talk_base::NetworkToHost32(*static_cast<const uint32*>(buf));
}

inline uint16 bytes_to_short(const void* buf) {
  return talk_base::NetworkToHost16(*static_cast<const uint16*>(buf));
}

uint32 bound(uint32 lower, uint32 middle, uint32 upper) {
  return talk_base::_min(talk_base::_max(lower, middle), upper);
}

//////////////////////////////////////////////////////////////////////
// Debugging Statistics
//////////////////////////////////////////////////////////////////////

#if 0  // Not used yet

enum Stat {
  S_SENT_PACKET,   // All packet sends
  S_RESENT_PACKET, // All packet sends that are retransmits
  S_RECV_PACKET,   // All packet receives
  S_RECV_NEW,      // All packet receives that are too new
  S_RECV_OLD,      // All packet receives that are too old
  S_NUM_STATS
};

const char* const STAT_NAMES[S_NUM_STATS] = {
  "snt",
  "snt-r",
  "rcv"
  "rcv-n",
  "rcv-o"
};

int g_stats[S_NUM_STATS];
inline void Incr(Stat s) { ++g_stats[s]; }
void ReportStats() {
  char buffer[256];
  size_t len = 0;
  for (int i=0; i<S_NUM_STATS; ++i) {
    len += talk_base::sprintfn(buffer, ARRAY_SIZE(buffer), "%s%s:%d",
                               (i == 0) ? "" : ",", STAT_NAMES[i], g_stats[i]);
    g_stats[i] = 0;
  }
  LOG(LS_INFO) << "Stats[" << buffer << "]";
}

#endif

//////////////////////////////////////////////////////////////////////
// PseudoTcp
//////////////////////////////////////////////////////////////////////

uint32 PseudoTcp::Now() {
#if 0  // Use this to synchronize timers with logging timestamps (easier debug)
  return talk_base::ElapsedTime();
#else
  return talk_base::Time();
#endif
}

PseudoTcp::PseudoTcp(IPseudoTcpNotify * notify, uint32 conv)
    : m_notify(notify), m_shutdown(SD_NONE), m_error(0) {

  // Sanity check on buffer sizes (needed for OnTcpWriteable notification logic)
  ASSERT(sizeof(m_rbuf) + MIN_PACKET < sizeof(m_sbuf));

  uint32 now = Now();

  m_state = TCP_LISTEN;
  m_conv = conv;
  m_rcv_wnd = sizeof(m_rbuf);
  m_snd_nxt = m_slen = 0;
  m_snd_wnd = 1;
  m_snd_una = m_rcv_nxt = m_rlen = 0;
  m_bReadEnable = true;
  m_bWriteEnable = false;
  m_t_ack = 0;

  m_msslevel = 0;
  m_largest = 0;
  ASSERT(MIN_PACKET > PACKET_OVERHEAD);
  m_mss = MIN_PACKET - PACKET_OVERHEAD;
  m_mtu_advise = MAX_PACKET;

  m_rto_base = 0;

  m_cwnd = 2 * m_mss;
  m_ssthresh = sizeof(m_rbuf);
  m_lastrecv = m_lastsend = m_lasttraffic = now;
  m_bOutgoing = false;

  m_dup_acks = 0;
  m_recover = 0;

  m_ts_recent = m_ts_lastack = 0;

  m_rx_rto = DEF_RTO;
  m_rx_srtt = m_rx_rttvar = 0;
}

PseudoTcp::~PseudoTcp() {
}

int
PseudoTcp::Connect() {
  if (m_state != TCP_LISTEN) {
    m_error = EINVAL;
    return -1;
  }

  m_state = TCP_SYN_SENT;
  LOG(LS_INFO) << "State: TCP_SYN_SENT";

  char buffer[1];
  buffer[0] = CTL_CONNECT;
  queue(buffer, 1, true);
  attemptSend();

  return 0;
}

void
PseudoTcp::NotifyMTU(uint16 mtu) {
  m_mtu_advise = mtu;
  if (m_state == TCP_ESTABLISHED) {
    adjustMTU();
  }
}

void
PseudoTcp::NotifyClock(uint32 now) {
  if (m_state == TCP_CLOSED)
    return;

    // Check if it's time to retransmit a segment
  if (m_rto_base && (talk_base::TimeDiff(m_rto_base + m_rx_rto, now) <= 0)) {
    if (m_slist.empty()) {
      ASSERT(false);
    } else {
      // Note: (m_slist.front().xmit == 0)) {
      // retransmit segments
#if _DEBUGMSG >= _DBG_NORMAL
      LOG(LS_INFO) << "timeout retransmit (rto: " << m_rx_rto
                   << ") (rto_base: " << m_rto_base
                   << ") (now: " << now
                   << ") (dup_acks: " << static_cast<unsigned>(m_dup_acks)
                   << ")";
#endif // _DEBUGMSG
      if (!transmit(m_slist.begin(), now)) {
        closedown(ECONNABORTED);
        return;
      }

      uint32 nInFlight = m_snd_nxt - m_snd_una;
      m_ssthresh = talk_base::_max(nInFlight / 2, 2 * m_mss);
      //LOG(LS_INFO) << "m_ssthresh: " << m_ssthresh << "  nInFlight: " << nInFlight << "  m_mss: " << m_mss;
      m_cwnd = m_mss;

      // Back off retransmit timer.  Note: the limit is lower when connecting.
      uint32 rto_limit = (m_state < TCP_ESTABLISHED) ? DEF_RTO : MAX_RTO;
      m_rx_rto = talk_base::_min(rto_limit, m_rx_rto * 2);
      m_rto_base = now;
    }
  }
  
  // Check if it's time to probe closed windows
  if ((m_snd_wnd == 0) 
        && (talk_base::TimeDiff(m_lastsend + m_rx_rto, now) <= 0)) {
    if (talk_base::TimeDiff(now, m_lastrecv) >= 15000) {
      closedown(ECONNABORTED);
      return;
    }

    // probe the window
    packet(m_snd_nxt - 1, 0, 0, 0);
    m_lastsend = now;

    // back off retransmit timer
    m_rx_rto = talk_base::_min(MAX_RTO, m_rx_rto * 2);
  }

  // Check if it's time to send delayed acks
  if (m_t_ack && (talk_base::TimeDiff(m_t_ack + ACK_DELAY, now) <= 0)) {
    packet(m_snd_nxt, 0, 0, 0);
  }

#if PSEUDO_KEEPALIVE
  // Check for idle timeout
  if ((m_state == TCP_ESTABLISHED) && (TimeDiff(m_lastrecv + IDLE_TIMEOUT, now) <= 0)) {
    closedown(ECONNABORTED);
    return;
  }

  // Check for ping timeout (to keep udp mapping open)
  if ((m_state == TCP_ESTABLISHED) && (TimeDiff(m_lasttraffic + (m_bOutgoing ? IDLE_PING * 3/2 : IDLE_PING), now) <= 0)) {