asterisk代码学习笔记

1、Asterisk1.2配置文件参数读取相关的ast_config_engine_registerreload_queues->ast_config_load->ast_config_internal_load->load_func(queues.conf时就是config_text_file_load)-> process_text_line-> ast_category_browse-> ast_variable_browse-> queue_set_paramasterisk.c/main-> read_config_maps-> as

2、t_config_internal_load-> config_text_file_load -> ast_variable_browse -> append_mappingchan_sip.c/ do_monitordo_monitor -> ast_io_add-> sip_do_reload-> sip_poke_all_peers -> sip_send_all_registers -> ast_softhangup_nolock-> ast_queue_frame -> pthread_testcancel -> as

3、t_sched_wait -> ast_io_wait-> sipsock_read -> ast_sched_runq /在调用callback时调用的函数是用ast_sched_add 时设置的回调。收到一个invite时的处理函数：系统初始化时：load_module ->restart_monitor 起一个线程>do_monitor一个死循环,接收sip信令,This thread monitors all the SIP sessions and peers that needs notification of mwi (and thus do not

4、 have a separate thread) indefinitely->ast_io_add/设置回调函数sipsock_read, Add an I/O event to our SIP UDP socket, 有事件时则回调sipsock_read 读取socket数据->rtp.c/ast_rtp_sendcng->ast_sched_wait->ast_io_wait/将调用sipsock_read->ast_sched_runq-> sip_send_mwi_to_peer在reload-> sip_reload-> restar

5、t_monitor 也会调用restart_monitor*Chan_sip.c/ sip_tech收到一个invite时的处理函数:sipsock_read ->parse_request/解析了消息的头部和体部，解析方法名 -> find_sip_method/找到方法名对应的ID -> find_call->get_header->gettag->sip_alloc/找不到/不存在，就分配一个,这里的是主叫的sip_pvt->handle_request-> get_header/当收到响应消息时，会调用handle_response -&

6、gt;handle_response-> hangup_sip2cause-> _sip_semi_ack-> _sip_ack-> handle_response_peerpoke-> transmit_request-> reqprep -> send_request-> _sip_xmit-> sendto-> handle_response_invite -> handle_request_options -> handle_request_refer -> handle_request_cancel -&g

7、t; handle_request_bye -> handle_request_message -> handle_request_subscribe -> handle_request_register -> handle_request_info /当收到invite时，会调用handle_request_invite-> handle_request_invite-> transmit_response_with_unsupported->respprep-> init_resp-> copy_via_headers-> _ge

8、t_header-> add_header-> copy_all_header -> _get_header -> add_header-> copy_header->send_response-> parse_copy->append_history-> _sip_xmit-> sendto -> transmit_response-> _transmit_response-> respprep -> send_response ->check_via ->find_sdp->process

9、_sdp/收到第一个invite时鉴权->check_user->check_user_full->find_peer->realtime_peer->ast_load_realtime ->check_auth_first->sip_new/分配主叫的ast_channel-> build_route->ast_pbx_start创建一个线程运行pbx_threadpbx_thread-> _ast_pbx_run-> ast_exists_extension-> pbx_extension_helper -> a

10、st_spawn_extension-> pbx_extension_helper-> pbx_exec->执行到Dial时，调用回调函数dial_exec，这个是通过load_module->ast_register_application注册的 -> ast_pbx_startdial_exec->dial_exec_full->ast_request(sip_request_call)-> sip_alloc/这里是被叫的sip_pvt -> sip_new/分配被叫的ast_channel ->create_addr->

11、find_peer-> realtime_peer-> ast_load_realtime -> build_peer-> handle_common_options ->sched.c/ast_sched_del->acl.c/ast_get_ip_or_srv->acl.c/ast_append_ha->callerid.c/ast_parse_caller_presentation->cdr.c/ast_cdr_amaflags2int->channel.c/ast_get_group->frame.c/ast_parse

12、_allow_disallow->config.c/ast_variable_new ->sched.c/ast_sched_del ->sched.c/ast_sched_add ->create_addr_from_peer ->srv.c/ast_get_srv->autoservice.c/ast_autoservice_start-> ast_pthread_create/autoservice_run ->dns.c/ast_search_dns-> dns_parse_answer ->autoservice.c/ast

13、_autoservice_stop-> pthread_kill -> ast_sip_ouraddrfor -> build_via -> build_callid -> sip_new->channel.c/ast_channel_alloc->sched.c/sched_context_create ->sched.c/sched_context_destroy ->ast_codec_choose ->ast_best_codec ->dsp.c/ast_dsp_new->dsp.c/ast_dtmf_detect

14、_init ->dsp.c/ast_dsp_prog_reset->dsp.c/goertzel_init ->dsp.c/ast_dsp_set_features ->dsp.c/ast_dsp_digitmode ->pbx.c/pbx_builtin_setvar_helper ->channel.c/ast_setstate ->channel.c/ast_hangup -> sip_destroy/ restart_monitor当收到一个invite时,这个函数会给monitor_thread 线程发送一个信号 -> resta

15、rt_monitor->do_monitor/当收到一个invite时,这里会给不会起线程,线程在系统初始化时就已经创建了/ast_call 函数在发出invite后返回，这里是把收到的来自主叫的invite转发给被叫,被叫是指上面使用ast_request分配资源的那个刚刚创建的被叫 -> ast_call(sip_call)-> transmit_invite-> build_via -> add_header -> copy_request -> parse_request -> add_sdp -> send_request -&g

16、t; ast_sched_add / wait_for_answer 函数被叫摘机应答后这个函数才返回-> wait_for_answer-> ast_waitfor_n->ast_bridge_call-> ast_answer-> sip_answer ->transmit_response_with_sdp(p, "200 OK", &p->initreq, 1)-> add_sdp /这里把从被叫收到的200ok消息发给主叫 /这里会更改从被叫收到的200OK中的sdp信息 -> ast_channel_

17、bridge(ast_rtp_bridge)循环调用 sip_rtp_read. ->ast_write->sip_write->ast_rtp_writeast_waitfor_nast_waitfor_n->ast_waitfor_nandfds-> ast_do_masquerade -> poll举个例子，当sipsock_read中读到了200 ok信令，会写到相应的通道的文件描述符，然后在ast_waitfor_n 中调用的poll函数会返回，判断收到的类型为信令，并且是200 ok，会调用bridge 相关的函数，然后在bridge中让然调用a

18、st_waitfor_n,读写rtp信息。在channel.c/ast_channel_alloc中的/* Always watch the alertpipe */tmp->fdsAST_MAX_FDS-1 = tmp->alertpipe0;/* And timing pipe */tmp->fdsAST_MAX_FDS-2 = tmp->timingfd;使通道的8个描述符中的最后2个监视信令。一般主线程(sipsock_read)通过ast_queue_frame 函数告诉描述符收到的信令(描述符是指在poll中监视的描述符)，然后poll返回，去处理收到的信令

19、。app_queue.c/wait_for_answer宏BUILD_WATCHERS是把主叫的channel(in)放在watchers的第一位，被叫的(坐席的)(o)放在后面。wait_for_answer->while(*to && !peer) ->ast_waitfor_n/这个函数返回可读写的channel(winner),不是in就是o, ->while(o) ->ast_read /收到被叫的信令时，会走到这里，180、200等，o指的是被叫。主叫此时在振铃或收听背景音，不会有信令，只有rtp ->if (winner = in)

20、->ast_read/读取主叫的rtp,一般是背景音乐，即MOH发送183和播放彩铃代码流程紫红色的是另外一种路径，这里要把ast_channel_alloc中的tmp->timingfd = open("/dev/zap/timer", O_RDWR);打开相关函数monmp3thread执行到Dial时，调用回调函数dial_exec->dial_exec->dial_exec_full->ast_request(sip_request_call)-> ast_call(sip_call)->ast_moh_start由于传给

21、Dial("SIP/8801-081b8c4c", "SIP/802802|25|tTrm()")的参数中有m，表示播放彩铃->local_ast_moh_start->ast_activate_generator->ast_prod/ Send empty audio to prime a channel driver-> ast_write->sip_write(chan->tech->write)->transmit_response_with_sdp发送183->ast_rtp_write发送

22、empty audio->moh_alloc->ast_settimeout这里设置timer来循环调用generator_forcegenerator_force调用generate(moh_generate)发送彩铃的rtp->设置channnel的chan->generator回调函数-> wait_for_answer->循环调用ast_waitfor_n-> ast_waitfor_nandfds-> poll-> ast_read (winner = in)-> generate(moh_generate)->moh

23、_generate->read ->ast_write>sip_write(chan->tech->write) ->transmit_response_with_sdp发送183 ->ast_rtp_write发送彩铃的rtpast_read->sip_read->sip_rtp_read->ast_rtp_read->ast_rtcp_readframe.c/ast_smootherast_prod-> ast_write(chan,frame)->sip_write(chan->tech->writ

24、e)->ast_rtp_write->ast_rtp_lookup_code ->ast_smoother_new ->ast_smoother_feed->_ast_smoother_feed ->ast_smoother_read ->ast_rtp_raw_writeapp_queue.cqueue_exec-> pbx_findapp -> pbx_exec ->pbx_builtin_getvar_helper -> join_queue -> ast_indicate -> ast_moh_start -

25、> wait_our_turn -> try_calling-> ring_one-> ring_entry->ast_request->sip_request_call->sip_alloc ->sip_new->ast_channel_alloc ->restart_monitor->pthread_kill(monitor_thread, SIGURG)-> ast_call(sip_call)-> transmit_invite->wait_for_answer/坐席摘机应答后wait_for_answ

26、er返回-> ast_bridge_callmanager.c/init_managerinit_manager-> ->创建线程运行accept_thread/等待客户端登录，为每个登录的客户端创建一个线程，分配一个mansession结构体。accept_thread->创建线程运行session_do/处理每隔线程的事务。session_do->process_message->authenticateformats/codecs目录A和B注册到asterisk，A发出的RTP（比如是alaw）到达asterisk，asterisk会调用formats

27、目录下的相应的文件进行解包（解析rtp的数据部分的内容）、重新打包，然后发到B端。如果A、B的编码方式不一样，还会调用codecs目录下的相应的文件。Formats目录下的模块都会调用file.c/ast_format_register函数。file.c app_queue.c/play_file 函数 调用方法 play_file(qe->chan,"gonghao");play_file->ast_stopstream->ast_closestream ->ast_streamfile->ast_openstream->ast_ope

28、nstream_full->ast_set_write_format->ast_openvstream ->ast_applystream-> ast_playstream-> ast_readaudio_callback-> (s->fmt->)read-> ast_write->ast_settimeout->ast_sched_add/在ast_readaudio_callback中会从文件中读取一帧写到通道中，然后起一个timer,在callback后会调用ast_readaudio_callback再发送一帧。 -&g

29、t; ast_readvideo_callback ->ast_waitstream->ast_sched_wait->ast_waitfor->ast_waitfor_n->ast_read->ast_sched_runq->(current->callback) ast_readaudio_callback ->ast_stopstream把对方hold住对方听背景音乐时，敲命令moh reloadippbx刚刚起来时会走到这里 load_moh_classes-> moh_register->创建线程monmp3threa

30、dmonmp3thread-> spawn_mp3->fork->write(moh->pipe1, sbuf, res2)/这里是循环调用把对方hold住对方听背景音乐收到INVITE消息，process_sdp->ast_moh_start->ast_moh_start_ptr(local_ast_moh_start)-> ast_activate_generator->moh_release->ast_prod ->moh_alloc->mohalloc->pipe->fcntl ->chan->g

31、enerator = gen/把mohgen付给chan->generator-> ast_rtp_stopast_read->generate(chan->generator->generate,实际是moh_generate)->read (moh->pipe0, buf + AST_FRIENDLY_OFFSET/2, len) ->ast_write (chan, &f)敲命令moh reloadmoh_cli-> moh_on_off(0)-> ast_deactivate_generator-> chan-&

32、gt;generator->release(moh_release) -> ast_moh_destroy->moh->pid = 0;->ast_moh_free_class -> load_moh_classes(1)-> moh_register->创建线程monmp3thread ->sleep(1)/创建线程需要时间的，要等线程创建好了再让rtp去读(就是调用ast_read->moh_generate),否则pid为0 -> moh_on_off(1)-> local_ast_moh_start-> as

33、t_activate_generator->moh_release->ast_prod->moh_alloc->mohalloc->pipe ->fcntl->chan->generator = gen/把mohgen付给chan->generator这时应该是重新开始放背景音乐music on hold在函数local_ast_moh_start 中会设置AST_FLAG_MOH标志，在ast_activate_generator中会调用moh_alloc分配mohdata结构体local_ast_moh_start->ast_ac

34、tivate_generator->ast_prod/发送一个空的帧->moh_alloc->mohalloc /创建管道，分配mohdata结构体,每个被hold住的channnel都会有这个结构体，在下面的write中会使用->chan->generator = gen /设置回调local_ast_moh_stop做和local_ast_moh_start相反的事情。load_moh_classes-> moh_register->创建线程运行monmp3thread,死循环-> class->srcfd =spawn_mp3/启动m

35、pg123进程 ->read(class->srcfd, sbuf, len)/class->srcfd是pipe 0,对应的pipe 1是有mpg123写入的。 ->write(moh->pipe1, sbuf, res2)/把从class->srcfd读出的内容写到moh->pepe1中，会循环写到每个客户的mohdata中。在moh_generate函数中会->read(moh->pipe0, buf + AST_FRIENDLY_OFFSET/2, len)/读取写入moh->pepe1中的内容 ->ast_write(

36、chan, &f)/发送到远端在 ast_read()中会调用moh_generategenerate = chan->generator->generate;res = generate(chan, tmp, f->datalen, f->samples);/will invoke moh_generate在queue_exec中，运行queue应用的线程应该是主叫的线程，这个线程在调用ast_moh_start后，就会返回，但是，运行ast_read函数的也是这个线程，是主叫线程运行到wait_for_answer函数，在这个函数中调用ast_read函数的

37、(wait_for_answer->ast_read)。chan_sip.c/sip_newsip_new->ast_channel_alloc-> sched_context_create -> tmp->tech = &sip_tech -> ast_codec_choose -> ast_best_codec -> ast_dsp_new -> ast_rtp_fdAsterisk1.4A打B简单通话的代码流程：系统初始化时：load_module ->restart_monitor 起一个线程>do_monito

38、r一个死循环,接收sip信令,This thread monitors all the SIP sessions and peers that needs notification of mwi (and thus do not have a separate thread) indefinitely->ast_io_add/设置回调函数sipsock_read, Add an I/O event to our SIP UDP socket, 有事件时则回调sipsock_read 读取socket数据->rtp.c/ast_rtp_sendcng->ast_sched_wa

39、it->ast_io_wait/将调用sipsock_read->ast_sched_runq-> sip_send_mwi_to_peer在reload-> sip_reload-> restart_monitor 也会调用restart_monitor*Chan_sip.c/ sip_tech收到一个invite时的处理函数:sipsock_read ->parse_request/解析了消息的头部和体部，解析方法名 -> find_sip_method/找到方法名对应的ID -> find_call->get_header->g

40、ettag->sip_alloc/找不到/不存在，就分配一个,这里的是主叫的sip_pvt->handle_request-> get_header/当收到响应消息时，会调用handle_response ->handle_response-> hangup_sip2cause-> _sip_semi_ack-> AST_SCHED_DEL(sched, cur->retransid) / Stopping retransmission-> _sip_ack-> handle_response_peerpoke-> transm

41、it_request-> reqprep -> send_request-> _sip_xmit-> sendto /这里是发送AST_CONTROL_RINGING ,_ast_queue_frame发送一个frame到chan->readq-> if 180 -> handle_response_invite->if 180 -> ast_queue_control-> ast_queue_frame-> _ast_queue_frame->AST_LIST_APPEND_LIST ->if 200 ->

42、handle_response_invite-> if 200 -> find_sdp -> process_sdp -> update_call_counter -> build_route -> set_address_from_contact -> ast_queue_control /发送AST_CONTROL_ANSWER -> transmit_request /向被叫回ack -> handle_request_options -> handle_request_refer -> handle_request_ca

43、ncel -> handle_request_bye -> handle_request_message -> handle_request_subscribe -> handle_request_register -> handle_request_info -> SIP_ACK-> _sip_ack / stops retransmission /当收到invite时，会调用handle_request_invite-> handle_request_invite-> transmit_response_with_unsupported

44、->respprep-> init_resp-> copy_via_headers-> _get_header-> add_header-> copy_all_header -> _get_header -> add_header-> copy_header->send_response-> parse_copy->append_history-> _sip_xmit-> sendto -> transmit_response-> _transmit_response-> respprep -

45、> send_response -> ast_queue_control -> _sip_ack -> transmit_response_reliable ->check_via/收到第一个invite时鉴权->check_user->check_user_full-> find_user-> ast_rtp_codec_setpref-> ast_smoother_reconfigure-> smoother_frame_feed -> check_auth-> transmit_response_with_au

46、th /发出407 -> sip_scheddestroy->find_peer->realtime_peer->ast_load_realtime -> ast_rtp_codec_setpref -> check_auth ->find_sdp->process_sdp->ast_queue_frame->update_call_counter->get_destination->get_rdnis->extract_uri->build_contact->sip_new/分配主叫的ast_chann

47、el-> build_routeif AST_STATE_DOWN-> transmit_provisional_response(p, "100 Trying", req, 0); /向主叫回100try->ast_pbx_start为主叫创建一个线程运行pbx_threadpbx_thread-> _ast_pbx_run-> ast_exists_extension-> pbx_extension_helper -> ast_spawn_extension-> pbx_extension_helper-> pbx_

48、exec->执行到Dial时，调用回调函数dial_execdial_exec->dial_exec_full->ast_request(sip_request_call)-> sip_alloc/这里是被叫的sip_pvt -> sip_new/分配被叫的ast_channel ->create_addr->find_peer-> realtime_peer-> ast_load_realtime -> build_peer-> handle_common_options ->sched.c/ast_sched_del-

49、>acl.c/ast_get_ip_or_srv->acl.c/ast_append_ha->callerid.c/ast_parse_caller_presentation->cdr.c/ast_cdr_amaflags2int->channel.c/ast_get_group->frame.c/ast_parse_allow_disallow->config.c/ast_variable_new ->sched.c/ast_sched_del ->sched.c/ast_sched_add ->create_addr_from_p

50、eer ->srv.c/ast_get_srv->autoservice.c/ast_autoservice_start-> ast_pthread_create/autoservice_run ->dns.c/ast_search_dns-> dns_parse_answer ->autoservice.c/ast_autoservice_stop-> pthread_kill -> ast_sip_ouraddrfor -> build_via -> build_callid -> sip_new->channel.c

51、/ast_channel_alloc->sched.c/sched_context_create ->sched.c/sched_context_destroy ->ast_codec_choose ->ast_best_codec ->dsp.c/ast_dsp_new->dsp.c/ast_dtmf_detect_init ->dsp.c/ast_dsp_prog_reset->dsp.c/goertzel_init ->dsp.c/ast_dsp_set_features ->dsp.c/ast_dsp_digitmode ->pbx.c/pbx_builtin_setvar_helper ->channel.c/ast_setstate ->channel.c/ast_hangup -> sip_destroy/ restart_monitor当收到一个invite时,这个函数会给monitor_thread 线程发送一个信号 -> restart_monitor->do_monitor/当收到一个invite时,这里会给不会起线程,线程在系统初始化时就已经创建了/ast_call 函数在发出invite后返回，这里是把