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