port.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.
 */

#if defined(_MSC_VER) && _MSC_VER < 1300
#pragma warning(disable:4786)
#endif

#include <errno.h>

#include <algorithm>
#include <iostream>
#include <vector>

#include "talk/base/asyncudpsocket.h"
#include "talk/base/asynctcpsocket.h"
#include "talk/base/helpers.h"
#include "talk/base/logging.h"
#include "talk/base/scoped_ptr.h"
#include "talk/base/socketadapters.h"
#include "talk/p2p/base/common.h"
#include "talk/p2p/base/port.h"

#if defined(_MSC_VER) && _MSC_VER < 1300
namespace std {
  using ::memcmp;
}
#endif

namespace {

// The length of time we wait before timing out readability on a connection.
const uint32 CONNECTION_READ_TIMEOUT = 30 * 1000; // 30 seconds

// The length of time we wait before timing out writability on a connection.
const uint32 CONNECTION_WRITE_TIMEOUT = 15 * 1000; // 15 seconds

// The length of time we wait before we become unwritable.
const uint32 CONNECTION_WRITE_CONNECT_TIMEOUT = 5 * 1000; // 5 seconds

// The number of pings that must fail to respond before we become unwritable.
const uint32 CONNECTION_WRITE_CONNECT_FAILURES = 5;

// This is the length of time that we wait for a ping response to come back.
const int CONNECTION_RESPONSE_TIMEOUT = 5 * 1000; // 5 seconds

// Determines whether we have seen at least the given maximum number of
// pings fail to have a response.
inline bool TooManyFailures(
    const std::vector<uint32>& pings_since_last_response,
    uint32 maximum_failures,
    uint32 rtt_estimate,
    uint32 now) {

  // If we haven't sent that many pings, then we can't have failed that many.
  if (pings_since_last_response.size() < maximum_failures)
    return false;

  // Check if the window in which we would expect a response to the ping has
  // already elapsed.
  return pings_since_last_response[maximum_failures - 1] + rtt_estimate < now;
}

// Determines whether we have gone too long without seeing any response.
inline bool TooLongWithoutResponse(
    const std::vector<uint32>& pings_since_last_response,
    uint32 maximum_time,
    uint32 now) {

  if (pings_since_last_response.size() == 0)
    return false;

  return pings_since_last_response[0] + maximum_time < now;
}

// We will restrict RTT estimates (when used for determining state) to be
// within a reasonable range.
const uint32 MINIMUM_RTT = 100;  // 0.1 seconds
const uint32 MAXIMUM_RTT = 3000; // 3 seconds

// When we don't have any RTT data, we have to pick something reasonable.  We
// use a large value just in case the connection is really slow.
const uint32 DEFAULT_RTT = MAXIMUM_RTT;

// Computes our estimate of the RTT given the current estimate and the number
// of data points on which it is based.
inline uint32 ConservativeRTTEstimate(uint32 rtt, uint32 rtt_data_points) {
  if (rtt_data_points == 0)
    return DEFAULT_RTT;
  else
    return talk_base::_max(MINIMUM_RTT, talk_base::_min(MAXIMUM_RTT, 2 * rtt));
}

// Weighting of the old rtt value to new data.
const int RTT_RATIO = 3; // 3 : 1

// The delay before we begin checking if this port is useless.
const int kPortTimeoutDelay = 30 * 1000; // 30 seconds

const uint32 MSG_CHECKTIMEOUT = 1;
const uint32 MSG_DELETE = 1;

}

namespace cricket {

static const char * const PROTO_NAMES[PROTO_LAST+1] = { "udp", "tcp", "ssltcp" };

const char * ProtoToString(ProtocolType proto) {
  return PROTO_NAMES[proto];
}

bool StringToProto(const char * value, ProtocolType& proto) {
  for (size_t i=0; i<=PROTO_LAST; ++i) {
    if (strcmp(PROTO_NAMES[i], value) == 0) {
      proto = static_cast<ProtocolType>(i);
      return true;
    }
  }
  return false;
}

std::string Port::agent_;
talk_base::ProxyInfo Port::proxy_;

Port::Port(talk_base::Thread* thread, const std::string& type, 
           talk_base::SocketFactory* factory, talk_base::Network* network)
  : thread_(thread), factory_(factory), type_(type), network_(network),
    preference_(-1), lifetime_(LT_PRESTART), enable_port_packets_(false) {

  if (factory_ == NULL)
    factory_ = thread_->socketserver();

  set_username_fragment(CreateRandomString(16));
  set_password(CreateRandomString(16));
}

Port::~Port() {
  // Delete all of the remaining connections.  We copy the list up front
  // because each deletion will cause it to be modified.

  std::vector<Connection*> list;

  AddressMap::iterator iter = connections_.begin();
  while (iter != connections_.end()) {
    list.push_back(iter->second);
    ++iter;
  }

  for (uint32 i = 0; i < list.size(); i++)
    delete list[i];
}

Connection* Port::GetConnection(const talk_base::SocketAddress& remote_addr) {
  AddressMap::const_iterator iter = connections_.find(remote_addr);
  if (iter != connections_.end())
    return iter->second;
  else
    return NULL;
}

void Port::AddAddress(const talk_base::SocketAddress& address,
                      const std::string& protocol,
                      bool final) {
  Candidate c;
  c.set_name(name_);
  c.set_type(type_);
  c.set_protocol(protocol);
  c.set_address(address);
  c.set_preference(preference_);
  c.set_username(username_frag_);
  c.set_password(password_);
  c.set_network_name(network_->name());
  c.set_generation(generation_);
  candidates_.push_back(c);

  if (final)
    SignalAddressReady(this);
}

void Port::AddConnection(Connection* conn) {
  connections_[conn->remote_candidate().address()] = conn;
  conn->SignalDestroyed.connect(this, &Port::OnConnectionDestroyed);
  SignalConnectionCreated(this, conn);
}

void Port::OnReadPacket(
    const char* data, size_t size, const talk_base::SocketAddress& addr) {
  // If the user has enabled port packets, just hand this over.
  if (enable_port_packets_) {
    SignalReadPacket(this, data, size, addr);
    return;
  }

  // If this is an authenticated STUN request, then signal unknown address and
  // send back a proper binding response.
  StunMessage* msg;
  std::string remote_username;
  if (!GetStunMessage(data, size, addr, msg, remote_username)) {
    LOG_J(LS_ERROR, this) << "Received non-STUN packet from unknown address ("
                          << addr.ToString() << ")";
  } else if (!msg) {
    // STUN message handled already
  } else if (msg->type() == STUN_BINDING_REQUEST) {
    SignalUnknownAddress(this, addr, msg, remote_username);
  } else {
    LOG_J(LS_ERROR, this) << "Received unexpected STUN message type ("
                          << msg->type() << ") from unknown address ("
                          << addr.ToString() << ")";
    delete msg;
  }
}

void Port::SendBindingRequest(Connection* conn) {

  // Construct the request message.

  StunMessage request;
  request.SetType(STUN_BINDING_REQUEST);
  request.SetTransactionID(CreateRandomString(16));

  StunByteStringAttribute* username_attr =
      StunAttribute::CreateByteString(STUN_ATTR_USERNAME);
  std::string username = conn->remote_candidate().username();
  username.append(username_frag_);
  username_attr->CopyBytes(username.c_str(), (uint16)username.size());
  request.AddAttribute(username_attr);

  // Send the request message.
  // NOTE: If we wanted to, this is where we would add the HMAC.
  talk_base::ByteBuffer buf;
  request.Write(&buf);
  SendTo(buf.Data(), buf.Length(), conn->remote_candidate().address(), false);
}

bool Port::GetStunMessage(const char* data, size_t size,
                          const talk_base::SocketAddress& addr, 
                          StunMessage *& msg, std::string& remote_username) {
  // NOTE: This could clearly be optimized to avoid allocating any memory.
  //       However, at the data rates we'll be looking at on the client side,
  //       this probably isn't worth worrying about.

  msg = 0;

  // Parse the request message.  If the packet is not a complete and correct
  // STUN message, then ignore it.
  talk_base::scoped_ptr<StunMessage> stun_msg(new StunMessage());
  talk_base::ByteBuffer buf(data, size);
  if (!stun_msg->Read(&buf) || (buf.Length() > 0)) {
    return false;
  }

  // The packet must include a username that either begins or ends with our
  // fragment.  It should begin with our fragment if it is a request and it
  // should end with our fragment if it is a response.
  const StunByteStringAttribute* username_attr =
      stun_msg->GetByteString(STUN_ATTR_USERNAME);

  int remote_frag_len = (username_attr ? username_attr->length() : 0);
  remote_frag_len -= static_cast<int>(username_frag_.size());

  if (stun_msg->type() == STUN_BINDING_REQUEST) {
    if ((remote_frag_len < 0)
        || (std::memcmp(username_attr->bytes(),
                        username_frag_.c_str(), username_frag_.size()) != 0)) {
      LOG_J(LS_ERROR, this) << "Received STUN request with bad username";
      SendBindingErrorResponse(stun_msg.get(), addr, STUN_ERROR_BAD_REQUEST,
        STUN_ERROR_REASON_BAD_REQUEST);
      return true;
    }

    remote_username.assign(username_attr->bytes() + username_frag_.size(),
      username_attr->bytes() + username_attr->length());
  } else if ((stun_msg->type() == STUN_BINDING_RESPONSE)
      || (stun_msg->type() == STUN_BINDING_ERROR_RESPONSE)) {
    if ((remote_frag_len < 0)
        || (std::memcmp(username_attr->bytes() + remote_frag_len,
                        username_frag_.c_str(), username_frag_.size()) != 0)) {
       LOG_J(LS_ERROR, this) << "Received STUN response with bad username";
      // Do not send error response to a response
      return true;
    }

    remote_username.assign(username_attr->bytes(),
      username_attr->bytes() + remote_frag_len);