groupsock.cpp

流媒体传输协议的实现代码,非常有用.可以支持rtsp mms等流媒体传输协议

/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**********/
// LIVE.COM Streaming Media Libraries
// Copyright (c) 1996-1999 Live Networks, Inc.  All rights reserved.
// 'Group sockets'
// Implementation

#include "Groupsock.hh"
#include "GroupsockHelper.hh"
//##### Eventually fix the following #include; we shouldn't know about tunnels
#include "TunnelEncaps.hh"

#ifndef NO_STRSTREAM
#if (defined(__WIN32__) || defined(_WIN32)) && !defined(__MINGW32__)
#include <strstrea.h>
#else
#if defined(__GNUC__) && (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ > 0)
#include <strstream>
#else
#include <strstream.h>
#endif
#endif
#endif
#include <stdio.h>

///////// OutputSocket //////////

OutputSocket::OutputSocket(UsageEnvironment& env)
  : Socket(env, 0 /* let kernel choose port */),
    fSourcePort(0), fLastSentTTL(0) {
}

OutputSocket::OutputSocket(UsageEnvironment& env, Port port)
  : Socket(env, port),
    fSourcePort(0), fLastSentTTL(0) {
}

OutputSocket::~OutputSocket() {
}

Boolean OutputSocket::write(netAddressBits address, Port port, u_int8_t ttl,
			    unsigned char* buffer, unsigned bufferSize) {
  if (ttl == fLastSentTTL) {
    // Optimization: So we don't do a 'set TTL' system call again
    ttl = 0;
  } else {
    fLastSentTTL = ttl;
  }
  struct in_addr destAddr; destAddr.s_addr = address;
  if (!writeSocket(env(), socketNum(), destAddr, port, ttl,
		   buffer, bufferSize))
    return False;
  
  if (sourcePortNum() == 0) {
    // Now that we've sent a packet, we can find out what the
    // kernel chose as our ephemeral source port number:
    if (!getSourcePort(env(), socketNum(), fSourcePort)) {
      if (DebugLevel >= 1)
	env() << *this
	     << ": failed to get source port: "
	     << env().getResultMsg() << "\n";
      return False;
    }
  }
  
  return True;
}

// By default, we don't do reads:
Boolean OutputSocket
::handleRead(unsigned char* /*buffer*/, unsigned /*bufferMaxSize*/,
	     unsigned& /*bytesRead*/, struct sockaddr_in& /*fromAddress*/) {
  return True;
}


///////// destRecord //////////

destRecord
::destRecord(struct in_addr const& addr, Port const& port, u_int8_t ttl,
	     destRecord* next)
  : fNext(next), fGroupEId(addr, port.num(), ttl), fPort(port) {
}

destRecord::~destRecord() {
  delete fNext;
}


///////// Groupsock //////////

NetInterfaceTrafficStats Groupsock::statsIncoming;
NetInterfaceTrafficStats Groupsock::statsOutgoing;
NetInterfaceTrafficStats Groupsock::statsRelayedIncoming;
NetInterfaceTrafficStats Groupsock::statsRelayedOutgoing;

// Constructor for a source-independent multicast group
Groupsock::Groupsock(UsageEnvironment& env, struct in_addr const& groupAddr,
		     Port port, u_int8_t ttl)
  : OutputSocket(env, port),
    deleteIfNoMembers(False), isSlave(False),
    fIncomingGroupEId(groupAddr, port.num(), ttl), fDests(NULL), fTTL(ttl) {
  addDestination(groupAddr, port);

  if (!socketJoinGroup(env, socketNum(), groupAddr.s_addr)) {
    if (DebugLevel >= 1) {
      env << *this << ": failed to join group: "
	  << env.getResultMsg() << "\n";
    }
  }
  
  // Make sure we can get our source address:
  if (ourSourceAddressForMulticast(env) == 0) {
    if (DebugLevel >= 0) { // this is a fatal error
      env << "Unable to determine our source address: "
	  << env.getResultMsg() << "\n";
    }
  }
  
  if (DebugLevel >= 2) env << *this << ": created\n";
}

// Constructor for a source-specific multicast group
Groupsock::Groupsock(UsageEnvironment& env, struct in_addr const& groupAddr,
		     struct in_addr const& sourceFilterAddr,
		     Port port)
  : OutputSocket(env, port),
    deleteIfNoMembers(False), isSlave(False),
    fIncomingGroupEId(groupAddr, sourceFilterAddr, port.num()),
    fDests(NULL), fTTL(255) {
  addDestination(groupAddr, port);

  // First try a SSM join.  If that fails, try a regular join:
  if (!socketJoinGroupSSM(env, socketNum(), groupAddr.s_addr,
			  sourceFilterAddr.s_addr)) {
    if (DebugLevel >= 3) {
      env << *this << ": SSM join failed: "
	  << env.getResultMsg();
      env << " - trying regular join instead\n";
    }
    if (!socketJoinGroup(env, socketNum(), groupAddr.s_addr)) {
      if (DebugLevel >= 1) {
	env << *this << ": failed to join group: "
	     << env.getResultMsg() << "\n";
      }
    }
  }
  
  if (DebugLevel >= 2) env << *this << ": created\n";
}

Groupsock::~Groupsock() {
  if (isSSM()) {
    if (!socketLeaveGroupSSM(env(), socketNum(), groupAddress().s_addr,
			     sourceFilterAddress().s_addr)) {
      socketLeaveGroup(env(), socketNum(), groupAddress().s_addr);
    }
  } else {
    socketLeaveGroup(env(), socketNum(), groupAddress().s_addr);
  }
  
  delete fDests;

  if (DebugLevel >= 2) env() << *this << ": deleting\n";
}

void
Groupsock::changeDestinationParameters(struct in_addr const& newDestAddr,
				       Port newDestPort, int newDestTTL) {
  if (fDests == NULL) return;

  struct in_addr destAddr = fDests->fGroupEId.groupAddress();
  if (newDestAddr.s_addr != 0) {
    if (newDestAddr.s_addr != destAddr.s_addr
	&& IsMulticastAddress(newDestAddr.s_addr)) {
      // If the new destination is a multicast address, then we assume that
      // we want to join it also.  (If this is not in fact the case, then
      // call "multicastSendOnly()" afterwards.)
      socketLeaveGroup(env(), socketNum(), destAddr.s_addr);
      socketJoinGroup(env(), socketNum(), newDestAddr.s_addr);
    }
    destAddr.s_addr = newDestAddr.s_addr;
  }

  portNumBits destPortNum = fDests->fGroupEId.portNum();
  if (newDestPort.num() != 0) {
    destPortNum = newDestPort.num();
    fDests->fPort = newDestPort;
  }

  u_int8_t destTTL = ttl();
  if (newDestTTL != ~0) destTTL = (u_int8_t)newDestTTL;

  fDests->fGroupEId = GroupEId(destAddr, destPortNum, destTTL);
}

void Groupsock::addDestination(struct in_addr const& addr, Port const& port) {
  // Check whether this destination is already known:
  for (destRecord* dests = fDests; dests != NULL; dests = dests->fNext) {
    if (addr.s_addr == dests->fGroupEId.groupAddress().s_addr
	&& port.num() == dests->fPort.num()) {
      return;
    }
  }

  fDests = new destRecord(addr, port, ttl(), fDests);
}

void Groupsock::removeDestination(struct in_addr const& addr, Port const& port) {
  for (destRecord** destsPtr = &fDests; *destsPtr != NULL;
       destsPtr = &((*destsPtr)->fNext)) {
    if (addr.s_addr == (*destsPtr)->fGroupEId.groupAddress().s_addr
	&& port.num() == (*destsPtr)->fPort.num()) {
      // Remove the record pointed to by *destsPtr :
      destRecord* next = (*destsPtr)->fNext;
      (*destsPtr)->fNext = NULL;
      delete (*destsPtr);
      *destsPtr = next;
      return;
    }
  }
}

void Groupsock::removeAllDestinations() {
  delete fDests; fDests = NULL;
}

void Groupsock::multicastSendOnly() {
  socketLeaveGroup(env(), socketNum(), fIncomingGroupEId.groupAddress().s_addr);
  for (destRecord* dests = fDests; dests != NULL; dests = dests->fNext) {
    socketLeaveGroup(env(), socketNum(), dests->fGroupEId.groupAddress().s_addr);
  }
}

Boolean Groupsock::output(UsageEnvironment& env, u_int8_t ttlToSend,
			  unsigned char* buffer, unsigned bufferSize,
			  DirectedNetInterface* interfaceNotToFwdBackTo) {
  do {
    // First, do the datagram send, to each destination:
    Boolean writeSuccess = True;
    for (destRecord* dests = fDests; dests != NULL; dests = dests->fNext) {
      if (!write(dests->fGroupEId.groupAddress().s_addr, dests->fPort, ttlToSend,
		 buffer, bufferSize)) {
	writeSuccess = False;
	break;
      }
    }
    if (!writeSuccess) break;
    statsOutgoing.countPacket(bufferSize);
    statsGroupOutgoing.countPacket(bufferSize);
    
    // Then, forward to our members:
    int numMembers =
      outputToAllMembersExcept(interfaceNotToFwdBackTo,
			       ttlToSend, buffer, bufferSize,
			       ourSourceAddressForMulticast(env));
    if (numMembers < 0) break;
    
    if (DebugLevel >= 3) {
      env << *this << ": wrote " << bufferSize << " bytes, ttl "
	  << (unsigned)ttlToSend;
      if (numMembers > 0) {
	env << "; relayed to " << numMembers << " members";
      }
      env << "\n";
    }
    return True;
  } while (0);
  
  if (DebugLevel >= 0) { // this is a fatal error
    env.setResultMsg("Groupsock write failed: ", env.getResultMsg());
  }
  return False;
}

Boolean Groupsock::handleRead(unsigned char* buffer, unsigned bufferMaxSize,
			      unsigned& bytesRead,
			      struct sockaddr_in& fromAddress) {
  // Read data from the socket, and relay it across any attached tunnels
  //##### later make this code more general - independent of tunnels
  
  bytesRead = 0;
  
  int maxBytesToRead = bufferMaxSize - TunnelEncapsulationTrailerMaxSize;
  int numBytes = readSocket(env(), socketNum(),
			    buffer, maxBytesToRead, fromAddress);
  if (numBytes < 0) {
    if (DebugLevel >= 0) { // this is a fatal error
      env().setResultMsg("Groupsock read failed: ",
			 env().getResultMsg());
    }
    return False;
  }
  
  // If we're a SSM group, make sure the source address matches:
  if (isSSM()
      && fromAddress.sin_addr.s_addr != sourceFilterAddress().s_addr) {
    return True;
  }
  
  // We'll handle this data.
  // Also write it (with the encapsulation trailer) to each member,
  // unless the packet was originally sent by us to begin with.
  bytesRead = numBytes;
  
  int numMembers = 0;