freeswitch呼叫流程分析

今天翻文档时发现之前整理的关于freeswitch呼叫相关的内容,写成博文分享出来也方便我以后查阅。

整体结构图

FreeswitchCore

模块加载过程

freeswitch主程序初始化时会从modules.conf.xml文件中读取配置,如果配置中如下内容生效:

<load module="mod_sofia"/>

则执行加载sofia模块操作。

具体过程如下:

main
switch_core_init_and_modload
switch_loadable_module_init
switch_loadable_module_load_module_ex : 读取xml文件并加载模块

状态机相关

状态机初始化

switch.c  : main

switch_core_init_and_modload
    => switch_core_init
        => switch_core_session_init
            => switch_core_session_thread_pool_manager
                => check_queue
                    => switch_core_session_thread_pool_worker
                        => switch_core_session_thread
                            => switch_core_session_run   

改变状态

通过调用switch_channel_set_state来实现状态机的状态改变。

处理状态变化

当状态发生变化后,通过switch_channel_set_running_state函数来改变running_state,

并执行相关的回调来通知其状态已经发生改变了:

endpoint_interface->io_routines->state_run

主叫状态变化

  • CS_NEW

switch_core_session_run初始状态为CS_NEW

  • CS_INIT

    sofia_handle_sip_i_state

    case nua_callstate_received (收到invite请求) 修改状态机的状态 :CS_NEW ==> CS_INIT switch_channel_set_state(channel, CS_INIT);

    switch_core_session_run

    状态机处理状态变化 STATE_MACRO(init, "INIT"); on_init 即 : sofia_on_init

    switch_core_standard_on_init

  • CS_ROUTING

    sofia_on_init

    修改状态机的状态 : CS_INIT == > CS_ROUTING
    switch_channel_set_state(channel, CS_ROUTING);

    switch_core_session_run

    状态机处理状态变化 STATE_MACRO(routing, "ROUTING"); on_routing 即 : sofia_on_routing

    switch_core_standard_on_routing

  • CS_EXECUTE

    switch_core_standard_on_routing 修改状态机的状态 : CS_ROUTING == > CS_EXECUTE switch_channel_set_state(session->channel, CS_EXECUTE);

    switch_core_session_run

    状态机处理状态变化 STATE_MACRO(execute, "EXECUTE"); on_execute 即 : sofia_on_execute

    switch_core_standard_on_execute

  • CS_HANGUP

    sofia_handle_sip_i_bye switch_channel_hangup : 即 switch_channel_perform_hangup 修改状态机的状态 channel->state = CS_HANGUP;

    状态机处理状态变化
        switch_core_session_hangup_state            
            STATE_MACRO(hangup, "HANGUP");

被叫状态变化

  • CS_NEW

switch_core_session_run初始状态为CS_NEW

  • CS_INIT

    sofia_outgoing_channel 修改状态机的状态 :CS_NEW ==> CS_INIT switch_channel_set_state(nchannel, CS_INIT);

状态机处理逻辑参考主叫。

  • CS_ROUTING

    sofia_on_init

    修改状态机的状态 : CS_INIT == > CS_ROUTING switch_channel_set_state(channel, CS_ROUTING);

状态机处理逻辑参考主叫。

  • CS_CONSUME_MEDIA

    originate_on_routing 修改状态机的状态:CS_ROUTING -> CS_CONSUME_MEDIA switch_channel_set_state(channel, CS_CONSUME_MEDIA);

    switch_core_session_run

    状态机处理状态变化 STATE_MACRO(consume_media, "CONSUME_MEDIA"); on_ consume_media 即 : NULL switch_core_standard_on_consume_media

  • CS_EXCHANGE_MEDIA

    switch_core_session_run

    状态机处理状态变化 STATE_MACRO(exchange_media, "EXCHANGE_MEDIA"); on_exchange_media 即 : sofia_on_exchange_media

    switch_core_standard_on_exchange_media

  • CS_HANGUP

    audio_bridge_on_exchange_media

    switch_channel_hangup : 即 switch_channel_perform_hangup 修改状态机的状态 channel->state = CS_HANGUP;

    状态机处理状态变化
        switch_core_session_hangup_state
    
            STATE_MACRO(hangup, "HANGUP");

Sofia应用层

模块加载过程

启动事件处理线程池 :

SWITCH_MODULE_LOAD_FUNCTION(mod_sofia_load)
    => sofia_msg_thread_start(0);
        => sofia_msg_thread_run
            => sofia_process_dispatch_event
                => our_sofia_event_callback : 处理消息

启动服务器监听 :

SWITCH_MODULE_LOAD_FUNCTION(mod_sofia_load)
    => config_sofia(0, NULL)
        => launch_sofia_profile_thread
            => sofia_profile_thread_run                
                => nua_create
                    => su_home_new
                    => nua_stack_init                    
                        => nta_agent_create
                            => nta_agent_add_tport                            
                                => tport_tbind
                                    => tport_bind_server
                                        => tport_listen : 监听客户端发来的数据   

数据表

数据库默认路径:/usr/local/freeswitch/db

freeswitch core 相关:

  • aliases
  • calls
  • channels
  • complete
  • interfaces
  • nat
  • recovery
  • registrations
  • tasks

sofia相关:

  • sip_authentication
  • sip_dialogs
  • sip_presence
  • sip_registrations
  • sip_shared_appearance_dialogs
  • sip_shared_appearance_subscriptions
  • sip_subscriptions

limit相关:

  • db_data
  • group_data
  • limit_data

fifo相关:

  • fifo_bridge
  • fifo_callers
  • fifo_outbound

语音信箱相关:

  • voicemail_msgs
  • voicemail_prefs

呼叫流程涉及内容

1、 收到A的nua_i_invite,返回407,具体如下:

sofia_handle_sip_i_invite => sofia_reg_handle_register => sofia_reg_auth_challenge => 407

2、 收到A的nua_i_invite,返回180,具体如下:

sofia_handle_sip_i_invite => sofia_reg_handle_register => sofia_reg_parse_auth

处理nua_i_state消息

sofia.c : sofia_handle_sip_i_state

...

mod_dialplan_xml.c : dialplan_hunt (ring_ready)

解析拨号方案,执行lua脚本,设置通道变量。

发送180事件

涉及数据表:

sip_registrations、ip_dialogs

3、 发送invite给B分机,具体如下:

处理nua_r_invite消息

sofia_handle_sip_r_invite => originate_on_routing

涉及数据表:

sip_dialogs

4、 B应答,双方通话,具体如下:

sofia_receive_message : SWITCH_MESSAGE_INDICATE_ANSWER               
    => sofia_answer_channel
        => sofia_glue_tech_choose_port
        => sofia_glue_set_local_sdp
        => sofia_glue_activate_rtp

编码协商过程

这里描述下后协商流程

  • 先匹配freeswitch默认的codec,从加载的模块中查找支持类型的具体码率信息

sofia_handle_sip_i_invite

=> sofia_glue_tech_prepare_codecs

=> switch_loadable_module_get_codecs_sorted

  • 协商发给被叫的sdp

sofia_glue_do_invite

=> sofia_glue_tech_prepare_codecs

=> switch_loadable_module_get_codecs_sorted

ocodec + codec_string
  • 产生M头,并发送包含sdp的invite

sofia_glue_do_invite

=> sofia_glue_set_local_sdp

=> generate_m

=> nua_invite

  • 协商200 OK的sdp

sofia_answer_channel

=> sofia_glue_tech_prepare_codecs

=> switch_loadable_module_get_codecs_sorted

媒体交互

  • RTP数据交互

audio_bridge_on_exchange_media

=> audio_bridge_thread

收发音频数据

=> switch_core_session_read_frame

=> session->endpoint_interface->io_routines->read_frame 即: sofia_read_frame

=> switch_core_session_write_frame

=> perform_write

=> session->endpoint_interface->io_routines->write_frame 即: sofia_write_frame

收发视频数据

1、启动线程

=> launch_video

=> video_bridge_thread

2、收发数据

=> switch_core_session_read_video_frame

=>session->endpoint_interface->io_routines->read_video_frame

即:sofia_read_video_frame

=> switch_core_session_write_video_frame

=> session->endpoint_interface->io_routines->write_video_frame

即:sofia_write_video_frame

  • 终止RTP交互

audio_bridge_thread

=> switch_core_session_kill_channel(session_b, SWITCH_SIG_BREAK);

即 :switch_core_session_perform_kill_channel

=> session->endpoint_interface->io_routines->kill_channel

即 : sofia_kill_channel

=> switch_rtp_break

Sofia协议栈

协议栈结构图

NUA : 基本的SIP用户代理的功能,其功能包括呼叫管理,消息和事件检索。

NTA : sofia SIP事务API(NTA)提供了简单的接口的SIP事务,传输和信息处理。

Tport : 该模块包含一个由SIP,RTSP 和HTTP协议使用的通用传输接口,这是一个协议栈和传输协议实现之间的抽象层。

SIP信令具体流程

场景描述: A 呼叫 B ,B接通后通话一段时间后,挂断电话。

  • A 发送 INVITE 请求

tport.c : tport_recv_data

nta.c : agent_recv_request

  • FS回应100给A分机

nua_server.c : nua_stack_process_request

nua_server.c : SR_STATUS1(sr, SIP_100_TRYING)

nta.c : nta_incoming_treply

nta.c : incoming_reply

tport.c: tport_tsend

  • FS发送认证请求给A分机

nua_application_event

处理nua_i_invite 消息

sofia.c : sofia_process_dispatch_event

sofia.c : our_sofia_event_callback

sofia.c : sofia_handle_sip_i_invite

sofia.c : sofia_reg_handle_register

sofia_reg.c : sofia_reg_auth_challenge

回复407

nua.c : nua_respond

nua_stack.c : nua_signal

nua_stack.c : nua_stack_signal

nua_server.c : nua_stack_respond

nua_server.c : nua_server_respond

发送407给A分机

nua_invite_server_respond

nua_base_server_respond

nta_incoming_mreply

incoming_reply

tport_tsend

tport_resolve

tport_by_addrinfo

tport_prepare_and_send

tport_send_msg

tport_vsend

sent 407 Proxy Authentication Required for INVITE (1)

call state(A) : init -> received

call state(A) : received -> terminated

  • A分机发送ACK

    nta.c : agent_recv_message

    nta.c : agent_recv_request

  • A分机重新发送 INVITE 请求,附加认证信息

    tport.c : tport_recv_data

    nta.c : agent_recv_request

  • FS回应100给A分机

nua_server.c : nua_stack_process_request

nua_server.c : SR_STATUS1(sr, SIP_100_TRYING)

nta.c : nta_incoming_treply

nta.c : incoming_reply

tport.c: tport_tsend

  • FS发送 INVITE 给 B分机

switch_ivr_originate.c : switch_ivr_originate

sofia_on_init

sofia_glue_do_invite

nua_invite : nua_r_invite 消息

nua_signal

sofia.c : sofia_process_dispatch_event

sofia.c : our_sofia_event_callback

sofia.c : sofia_handle_sip_r_invite

...

sofia_on_init

sofia_on_routing

switch_ivr_originate.c :originate_on_routing

...

nua_stack_signal

nua_stack_invite

...

nta_leg_tcreate

...

执行发送invite请求

nta.c : outgoing_send

tport_tsend

call state(B) : init -> calling

  • B分机回应180给FS

    tport_recv_event

    agent_recv_response

处理 nua_r_invite 消息

sofia.c : sofia_process_dispatch_event

sofia.c : our_sofia_event_callback

sofia.c : sofia_handle_sip_r_invite

call state(B) : calling -> proceeding

  • FS发送180给A分机

nua_session.c : signal_call_state_change

nua_stack_tevent : nua_i_state

nua_application_event

处理nua_i_invite 消息

sofia.c : sofia_process_dispatch_event

sofia.c : our_sofia_event_callback

sofia.c : sofia_handle_sip_i_invite

sofia_reg.c : sofia_reg_handle_register

sofia_reg.c : sofia_reg_parse_auth

处理nua_i_state消息

sofia.c : sofia_handle_sip_i_state

...

mod_dialplan_xml.c : dialplan_hunt (ring_ready)

解析拨号方案,执行lua脚本,设置通道变量。

发送180

switch_channel_mark_ring_ready

nua_invite_server_respond

nua_base_server_respond

nta_incoming_mreply

incoming_reply

tport_tsend

tport_resolve

tport_by_addrinfo

tport_prepare_and_send

tport_send_msg

tport_vsend

call state(A) : init -> received

 B发送200 ok

tport_recv_event

agent_recv_response

处理 nua_r_invite 消息

sofia.c : sofia_process_dispatch_event

sofia.c : our_sofia_event_callback

sofia.c : sofia_handle_sip_r_invite

call state(B) : proceeding -> completing

  • FS发送ACK给B

    nua_ack

    nua_signal : nua_r_ack

    outgoing_send

    tport_tsend

call state(A) : received -> early

call state(B) : completing -> ready

  • FS发送200 OK给A

    sofia_glue_tech_set_codec

    switch_rtp_create

    sofia_glue_negotiate_sdp

    sofia_glue_activate_rtp

    ...

    switch_channel_perform_answer : SWITCH_MESSAGE_INDICATE_ANSWER

    switch_channel_perform_mark_answered

    ...

    auto_record.lua : 执行录音操作B

    ...

    auto_record.lua : 执行录音操作A

    ...

    sofia_receive_message (SWITCH_MESSAGE_INDICATE_ANSWER)

    ...

    发送200 OK

    nua_respond : 200

    nua_signal : nua_r_respond

    nua_stack_signal

    nua_stack_respond

    nua_server_respond

    nta_incoming_treply

    nta_incoming_mreply

    incoming_reply

    tport_tsend

call state(A) : early -> completed

  • A回应ACK

    nta.c : agent_recv_message

    nta.c : agent_recv_request

call state(A) : completed -> ready

  • 通话一段时间后,A主动发送BYE

    tport_recv_event

    agent_recv_message

    agent_recv_request

    ...

    sofia_on_hangup

  • FS发送BYE给B

    nua_bye : nua_r_bye

    nua_stack_signal

    outgoing_send

    tport_tsend

  • FS发送200 OK给A

    nta : sent 200 OK for BYE

    tport_tsend

call state(A) : ready -> terminating

call state(A) : terminated

  • B发送200 OK给FS,回应挂断请求

    nta: received 200 OK for BYE

状态变化:

call state(B) : ready -> terminating

call state(B) : terminating -> terminated

本文github地址:

https://github.com/mike-zhang/mikeBlogEssays/blob/master/2016/20160907_freeswitch呼叫流程分析 .md

欢迎补充 

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