（點(diǎn)擊放大）

if ( UaConfiguration::instance()->getCallWaitingOn() )
{
//通知當(dāng)前的等待隊(duì)列中的消息準(zhǔn)備準(zhǔn)備開始和B進(jìn)行通訊，主要方式是把它的Call ID掛入//myeventQ中，由SipThread處理在隊(duì)列里的消息。
Sptr < UaCallContainer > calls;
calls.dynamicCast( event->getCallContainer() );
assert( calls != 0 );
Sptr < UaCallInfo > call2 = calls->findCall( *call2Id );

Sptr < Fifo < Sptr < SipProxyEvent > > > eventQ = deviceEvent->getFifo();
Sptr < UaDeviceEvent > event = new UaDeviceEvent( eventQ );
event->type = DeviceEventFlash;
event->callId = call2Id;
eventQ->add( event );

// 把當(dāng)前的A-B通訊裝入等待隊(duì)列中等待；
Sptr < SipCallId > callId = UaDevice::instance()->getCallId();
UaDevice::instance()->setCallId( 0 );
UaDevice::instance()->addCallWaitingId( callId );
}
//準(zhǔn)備回送給A端發(fā)送SDP的"C"為0.0.0.0的Invite消息，并且在Cseq為上一個(gè)的累加；
Sptr < UaCallInfo > call;
call.dynamicCast( event->getCallInfo() );
assert( call != 0 );

// Put current contact on hold
Sptr < InviteMsg > reInvite;

Sptr < Contact > contact = call->getContact();
assert( contact != 0 );

int status = contact->getStatus();
if ( status == 200 )
{
//在作為呼叫方的時(shí)候，這個(gè)Invite消息非常好制作，大部分只要復(fù)制上一個(gè)的一些內(nèi)//容就可以了。
const StatusMsg& msg = contact->getStatusMsg();
if ( &msg != 0 )
{
reInvite = new InviteMsg( msg );

//add SDP
Sptr < SipSdp > localSdp = call->getLocalSdp();
assert( localSdp != 0 );
SipSdp sipSdp = *localSdp;
reInvite->setContentData( &sipSdp );
}
… …
}
else
{
//在作為被叫方的時(shí)候，這個(gè)Invite消息就比較麻煩了，基本上要重新創(chuàng)立。

const InviteMsg& msg = contact->getInviteMsg();
if ( &msg != 0 )
{
string sipPort = UaConfiguration::instance()->getLocalSipPort();
reInvite = new InviteMsg( msg.getFrom().getUrl(),
atoi( sipPort.c_str() ) );
SipFrom from( msg.getTo().getUrl() );
reInvite->setFrom( from );

reInvite->setCallId( msg.getCallId() );

// Convert RecordRoute to reverse Route
int numRecordRoute = msg.getNumRecordRoute();
SipRecordRoute recordroute;
SipRoute route;

for ( int i = 0; i < numRecordRoute; i++ )
{
recordroute = msg.getRecordRoute( i );
route.setUrl( recordroute.getUrl() );
reInvite->setRoute( route ); // to beginning
}

int numContact = msg.getNumContact();
if ( numContact )
{
SipContact contact = msg.getContact( numContact - 1 );
route.setUrl( contact.getUrl() );
reInvite->setRoute( route ); // to beginning
}

}

}
assert( reInvite != 0 );

SipVia sipVia;
sipVia.setprotoVersion( "2.0" );
sipVia.setHost( Data( theSystem.gethostAddress() ) );
sipVia.setPort( atoi( UaConfiguration::instance()->getLocalSipPort().c_str() ) );
reInvite->flushViaList();
reInvite->setVia( sipVia, 0 );

// Set Contact: header
Sptr< SipUrl > myUrl = new SipUrl;
myUrl->setUserValue( UaConfiguration::instance()->getUserName(), "phone" );
myUrl->setHost( Data( theSystem.gethostAddress() ) );
myUrl->setPort( atoi( UaConfiguration::instance()->getLocalSipPort().c_str() ) );
SipContact me;
me.setUrl( myUrl );
reInvite->setNumContact( 0 ); // Clear
reInvite->setContact( me );

//TODO Is it going to be a problem if the other side also use the next
//TODO CSeq at the same time?
unsigned int cseq = contact->getCSeqNum();
contact->setCSeqNum( ++cseq );
SipCSeq sipCSeq = reInvite->getCSeq();
sipCSeq.setCSeq( cseq );
reInvite->setCSeq( sipCSeq );

Sptr<SipSdp> sipSdp;
sipSdp.dynamicCast ( reInvite->getContentData( 0 ) );
assert ( sipSdp != 0 );
SdpSession sdpDesc = sipSdp->getSdpDescriptor();
//在這里把SDP的C=0.0.0.0（hold項(xiàng)）設(shè)定；
sdpDesc.setHold();
sipSdp->setSdpDescriptor( sdpDesc );
//發(fā)送Reinvite消息到A端。
deviceEvent->getSipStack()->sendAsync( *reInvite );
Sptr < UaStateMachine > stateMachine;
stateMachine.dynamicCast( event->getCallInfo()->getFeature() );
assert( stateMachine != 0 );
//轉(zhuǎn)程序到StateOnhold
return stateMachine->findState( "StateOnhold" );
}
b.OpReinvite:
OpReinvite在接收到由通訊的對(duì)端Invite消息以后，把消息內(nèi)的 RemoteSDP放在本地的UaCallInfo中然后回送一個(gè)OK消息給對(duì)端；
c.OpEndCall:
OpEndCall在檢測(cè)到Bye消息發(fā)送以后，讓程序回送OK消息并且進(jìn)入StateCallEnded狀態(tài)中；
d.OpRevert:
OpRevert檢測(cè)到再次有DeviceEventFlash消息的時(shí)候本地開始發(fā)送INVITE消息，把等待方`處于等待的呼叫喚起；
e.StateCallEnded狀態(tài)：
StateCallEnded同樣是檢測(cè)DeviceEventFlash的消息，檢測(cè)到以后把調(diào)用OpConvertCw的操作，把處于等待隊(duì)列里的呼叫喚起。

（未完待續(xù)）

在Vovida的基礎(chǔ)上實(shí)現(xiàn)自己的SIP協(xié)議棧（六）

作者聯(lián)系方法：lu_zheng@21cn.com

作者供稿 CTI論壇編輯