linphone源码分析----初始化部分

这几天比较轻松，所以打算好好来看看linphone的代码，源码版本为3.5.2。从linphone初始化的过程开始，首先来看linphone_core_new函数。

LinphoneCore *linphone_core_new(const LinphoneCoreVTable *vtable,
const char *config_path, const char *factory_config_path, void * userdata)
{
LinphoneCore *core=ms_new(LinphoneCore,1);
linphone_core_init(core,vtable,config_path, factory_config_path, userdata);
return core;
}

主要工作基本上在函数linphone_core_init中实现

static void linphone_core_init (LinphoneCore * lc, const LinphoneCoreVTable *vtable, const char *config_path,
const char *factory_config_path, void * userdata)
{
memset (lc, 0, sizeof (LinphoneCore));
lc->data=userdata;
lc->ringstream_autorelease=TRUE;

memcpy(&lc->vtable,vtable,sizeof(LinphoneCoreVTable));  //保存了回调函数表

linphone_core_set_state(lc,LinphoneGlobalStartup,"Starting up");  //设置linphone内部状态
ortp_init();  //ortp模块初始化
lc->dyn_pt=96;  //负载类型从96开始都是动态负载类型
linphone_core_assign_payload_type(lc,&payload_type_pcmu8000,0,NULL);
linphone_core_assign_payload_type(lc,&payload_type_gsm,3,NULL);
linphone_core_assign_payload_type(lc,&payload_type_pcma8000,8,NULL);
linphone_core_assign_payload_type(lc,&payload_type_speex_nb,110,"vbr=on");
linphone_core_assign_payload_type(lc,&payload_type_speex_wb,111,"vbr=on");
linphone_core_assign_payload_type(lc,&payload_type_speex_uwb,112,"vbr=on");
linphone_core_assign_payload_type(lc,&payload_type_telephone_event,101,"0-11");
linphone_core_assign_payload_type(lc,&payload_type_g722,9,NULL);

#if defined(ANDROID) || defined (__IPHONE_OS_VERSION_MIN_REQUIRED)
/*shorten the DNS lookup time and send more retransmissions on mobiles:
- to workaround potential packet losses
- to avoid hanging for 30 seconds when the network doesn't work despite the phone thinks it does.
*/
_linphone_core_configure_resolver();
#endif

#ifdef ENABLE_NONSTANDARD_GSM
{
PayloadType *pt;
pt=payload_type_clone(&payload_type_gsm);
pt->clock_rate=11025;
linphone_core_assign_payload_type(lc,pt,-1,NULL);
pt->clock_rate=22050;
linphone_core_assign_payload_type(lc,pt,-1,NULL);
payload_type_destroy(pt);
}
#endif

#ifdef VIDEO_ENABLED
linphone_core_assign_payload_type(lc,&payload_type_h263,34,NULL);
linphone_core_assign_payload_type(lc,&payload_type_theora,97,NULL);
linphone_core_assign_payload_type(lc,&payload_type_h263_1998,98,"CIF=1;QCIF=1");
linphone_core_assign_payload_type(lc,&payload_type_mp4v,99,"profile-level-id=3");
linphone_core_assign_payload_type(lc,&payload_type_h264,102,"profile-level-id=428014");
linphone_core_assign_payload_type(lc,&payload_type_vp8,103,NULL);
linphone_core_assign_payload_type(lc,&payload_type_x_snow,-1,NULL);
/* due to limited space in SDP, we have to disable this h264 line which is normally no more necessary */
/* linphone_core_assign_payload_type(&payload_type_h264,-1,"packetization-mode=1;profile-level-id=428014");*/
#endif

//下面的这些负载类型，没有指定类型号
/*add all payload type for which we don't care about the number */
linphone_core_assign_payload_type(lc,&payload_type_ilbc,-1,"mode=30");
linphone_core_assign_payload_type(lc,&payload_type_amr,-1,"octet-align=1");
linphone_core_assign_payload_type(lc,&payload_type_amrwb,-1,"octet-align=1");
linphone_core_assign_payload_type(lc,&payload_type_lpc1015,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_g726_16,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_g726_24,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_g726_32,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_g726_40,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_aal2_g726_16,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_aal2_g726_24,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_aal2_g726_32,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_aal2_g726_40,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_silk_nb,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_silk_mb,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_silk_wb,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_silk_swb,-1,NULL);
linphone_core_assign_payload_type(lc,&payload_type_g729,18,"annexb=no");

ms_init();  //初始化mediastreamer模块
/* create a mediastreamer2 event queue and set it as global */
/* This allows to run event's callback in linphone_core_iterate() */
lc->msevq=ms_event_queue_new();  //事件队列，linphone_core_iterate函数中取出事件并调用相应的回调函数
ms_set_global_event_queue(lc->msevq);  //队列指针保存到一个全局的变量ms_global_event_queue里

lc->config=lp_config_new(config_path);  //读取配置文件，config保存的是一个ini文档，类似xml文档　　
if (factory_config_path)  //出厂配置文件是只读的，用于恢复出厂配置
lp_config_read_file(lc->config,factory_config_path);

lc->sal=sal_init();  //初始化exosip模块，sal是什么的缩写呢？
sal_set_user_pointer(lc->sal,lc);
sal_set_callbacks(lc->sal,&linphone_sal_callbacks);  //设置sal回调函数

sip_setup_register_all();  //这里将加载所有插件
sound_config_read(lc);  //读取音频相关配置
net_config_read(lc);  //读取网络相关配置
rtp_config_read(lc);  //读取rtp相关配置
codecs_config_read(lc);  //读取编码器相关配置
sip_config_read(lc);   //读取sip协议相关配置，/* this will start eXosip*/
video_config_read(lc);　//视频相关配置
//autoreplier_config_init(&lc->autoreplier_conf);
lc->presence_mode=LinphoneStatusOnline;  //在线、离线，还是其它
misc_config_read(lc);  //配置最大历史记录条数等
ui_config_read(lc);  //读取联系人(朋友)，读取通话记录
#ifdef TUNNEL_ENABLED
lc->tunnel=linphone_core_tunnel_new(lc);
if (lc->tunnel) linphone_tunnel_configure(lc->tunnel);
#endif
if (lc->vtable.display_status)
lc->vtable.display_status(lc,_("Ready"));  //更新状态
lc->auto_net_state_mon=lc->sip_conf.auto_net_state_mon;
linphone_core_set_state(lc,LinphoneGlobalOn,"Ready");  //这里将会调用状态改变的回调函数
}

上面的代码做了大量的工作，分配负载类型，初始化了各子模块，如ortp、sal(对exosip的封装吧)、mediastream2，加载了所有的插件，最后读取配置文件。

再来看看分配负载类型的函数linphone_core_assign_payload_type的实现

static void linphone_core_assign_payload_type(LinphoneCore *lc, PayloadType *const_pt, int number, const char *recv_fmtp){
PayloadType *pt;
pt=payload_type_clone(const_pt);

//找一个未分配的负载类型码，分配给本负载类型
if (number==-1){
/*look for a free number */
MSList *elem;
int i;
for(i=lc->dyn_pt;i<=127;++i){
bool_t already_assigned=FALSE;
for(elem=lc->payload_types;elem!=NULL;elem=elem->next){
PayloadType *it=(PayloadType*)elem->data;
if (payload_type_get_number(it)==i){
already_assigned=TRUE;
break;
}
}
if (!already_assigned){
number=i;
lc->dyn_pt=i+1;
break;
}
}
if (number==-1){
ms_fatal("FIXME: too many codecs, no more free numbers.");
}
}
ms_message("assigning %s/%i payload type number %i",pt->mime_type,pt->clock_rate,number);
payload_type_set_number(pt,number);
if (recv_fmtp!=NULL) payload_type_set_recv_fmtp(pt,recv_fmtp);
rtp_profile_set_payload(&av_profile,number,pt);  //将负载类型的对应关系保存到全局的RtpProfile结构中
lc->payload_types=ms_list_append(lc->payload_types,pt);  //将支持的负载类型添加到链表中
}