QuteCom手记：exosip初始化和构建INVITE请求

最新推荐文章于 2023-04-12 15:21:28 发布

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最新推荐文章于 2023-04-12 15:21:28 发布

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分类专栏： QuteCom手记文章标签： dialog null build user 服务器 random

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本文详细介绍了QuteCom中exosip的初始化过程，包括在`owplInit()`函数中设置SIP包头的User-Agent。此外，还探讨了如何构建INVITE请求，用于拨出电话。调用流程从`PhApiWrapper::makeCall()`开始，最终通过`eXosip_build_initial_invite()`函数生成INVITE消息。实现细节位于`generating_request_out_of_dialog2`函数中，该函数利用oSip2库设置INVITE请求的各种头域。

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@1、exosip初始化

qutecom/wifo/phapi/phapi.c

fun:owplInit()

Line:291

eXosip_set_user_agent(ua);设置SIP包头域User-Agent="qutecom/rev-335d495adbc1-trunk",即SIP客户端名称。

return_code = eXosip_init(0,0,udpPort,tcpPort,tlsPort);  
if (return_code != 0){
    owplLogError("eXosip_init failed");    
    return OWPL_RESULT_FAILURE;  
    }  
//...  
    {    
       const char * ua=QUTECOM_UA;
       eXosip_set_user_agent(ua);
    }

@2、创建一个INVITE请求包

拨出电话需要构建一个INVITE发给服务器，服务器转发给另一个UAC。

调用关系：

PhApiWrapper::makeCall()

==>owplCallConnect()

==>phLinePlaceCall_withCa()

==>eXosip_build_initial_invite()

函数声明：

qutecom/wifo/eXosip/include/eXosip/eXosip.h

/**
 * Build a default INVITE message for a new call.
 * 
 * @param invite    Pointer for the SIP element to hold.
 * @param to        SIP url for callee. * @param from      SIP url for caller.
 * @param route     Route header for INVITE. (optionnal)
 * @param subject   Subject for the call.
 */
int   eXosip_build_initial_invite(osip_message_t **invite, char *to, char *from, char *route, char *subject);

作用：

构建一个INVITE消息。

实现：

File: qutecom/wifo/eXosip/src/jrequest.c

/* this method can't be called unless the previous   INVITE transaction is over. */
int eXosip_build_initial_invite(osip_message_t **invite, char *to, char *from,char *route, char *subject){
  int i;  if (to!=NULL && *to=='/0')
    return -1;  osip_clrspace(to);
//清除空格  osip_clrspace(subject);
  osip_clrspace(from);
  osip_clrspace(route);
  if (route!=NULL && *route=='/0')
    route=NULL;
  if (subject!=NULL && *subject=='/0')
    subject=NULL;
//构建INVITE包
  i = generating_request_out_of_dialog(invite, "INVITE", to, from, route);
  if (i!=0) return -1;
#if 0  if (subject==NULL)
  osip_message_set_subject(*invite, "New Call");
  else  osip_message_set_subject(*invite, subject);
#else  if (subject!=NULL)
  osip_message_set_subject(*invite, subject);
  //设置SIP头域的SUBJECT字段 //"Subject: Phone call"
#endif  /* after this delay, we should send a CANCEL */
//设置超时
  owsip_message_set_expires(*invite, "120");
  /* osip_message_set_organization(*invite, "Jack's Org"); */
  return 0;}

函数generating_request_out_of_dialog调用generating_request_out_of_dialog2

generating_request_out_of_dialog2在qutecom/wifo/eXosip/src/jrequest.c实现

部分代码

static intgenerating_request_out_of_dialog2(osip_message_t **dest, char *method_name, char *to, char *from, char *proxy, int seqnum){
  //...
  i = osip_message_init(&request);
//初始化  if (i!=0) return -1;
  /* prepare the request-line */
  osip_message_set_method(request, osip_strdup(method_name));
  osip_message_set_version(request, osip_strdup("SIP/2.0"));//"INVITE sip:to@192.168.105.14 SIP/2.0"
  osip_message_set_status_code(request, 0);
  osip_message_set_reason_phrase(request, NULL);//
  //...
    i = osip_message_set_to(request, to);//"To: <sip:to@192.168.105.14>"
  //...
    osip_message_set_from(request, from);//
    osip_from_set_tag(request->from, osip_from_tag_new_random());//"rom: <sip:from@192.168.105.5>;tag=29244"
  //...
  osip_call_id_set_number(callid, cidrand);//"Call-ID: 8103"
  //...  osip_cseq_set_number(cseq, num);
  osip_cseq_set_method(cseq, osip_strdup(method_name));
          request->cseq = cseq; //"CSeq: 20 INVITE"
  //...
  osip_message_set_max_forwards(request, "70");
 /* a UA should start a request with 70 */
  //Max-Forwards: 70
     //...
  osip_message_set_via(request, tmp);//"Via: SIP/2.0/UDP 192.168.105.5:5060;rport;branch=z9hG4bK2195"
  //...
  osip_message_set_contact (request, contact) ;//"Contact: <sip:from@192.168.105.5:5060>"
  //...
  osip_message_set_user_agent(request, eXosip.user_agent);//"User-Agent: QuteCom2.2.1 (eXosip2/3.3.0)"
  //...
  //设定完头域后，INVITE消息应该长得像这样：
  //INVITE sip:to@192.168.105.14 SIP/2.0   
  //Via: SIP/2.0/UDP 192.168.105.5:5060;rport;branch=z9hG4bK2195   
  //From: <sip:from@192.168.105.5>;tag=29244   
  //To: <sip:to@192.168.105.14>   
  //Call-ID: 8103   
  //CSeq: 20 INVITE   
  //Contact: <sip:from@192.168.105.5:5060>    
  //Max-Forwards: 70   
  //User-Agent: Linphone/3.2.1 (eXosip2/3.3.0)   
  //Subject: Phone call  //subject在eXosip_build_initial_invite中被设置。在本函数调用后随即调用
}

这个函数调用了oSip2库的一系列xxsetxx函数设置INVITE包的各个头域。

头域的定义在《sip中文参考手册》P122 20 头域一节有完整说明

《sip中文参考手册》已经放在资源中。