libresbc实现原理

介绍

上一章我们介绍了libresbc的部署方式以及使用webui查看配置页面, 本章我们介绍一下libresbc原理。

架构

libresbc的架构图如下：

libresbc 架构图

webui: 这块是源码中的webui目录下的golang程序，用于查看和配置libresbc的参数。
main.py: 在源码中的liberator/main.py是libresbc的主程序, 具有一下功能:
- 监听http请求, 把配置参数保存到redis中。
- 启动freeswitch进程, 建立ESL 连接, 用于接收freeswitch的事件。
- 发布/订阅redis事件, 接收到事件之后，通知freeswitch进行相应的操作。
- 接收redis的cdr事件, 然后写文件或者发送到第三方的http server。
nftables: 这个是防火墙，用于设置黑白名单拦截，如果libresbc是容器部署的，那么nftables不起作用。
freeswitch: 这里的freeswitch用作sip server管理，可以设置sip profile,gateway等。
kamailio: 只有在页面设置了Connections->Access Service, 才会启动kamailio进程, kamailio使用的是kami功能。 kamailio没配置媒体代理,所以只能转sip协议, 不能转rtp协议。

另外， liberator目录下的*.j2.*文件，会被替换成对应的配置文件。

配置解析

libresbc关于freeswitch的重要配置是liberator/fscfg/xml/freeswitch.xml, 它把freeswitch的acl,diaplan,gateway都写到了一个.xml中,这里是完整的配置。

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<?xml version="1.0"?>
<document type="freeswitch/xml">
  <X-PRE-PROCESS cmd="set" data="preprocess_exec=true"/>
  <X-PRE-PROCESS cmd="exec-set" data="fsxmlapi=(echo ${LIBERATOR_CFGAPI_URL:-http://127.0.0.1:8080/cfgapi/fsxml})"/>
  <X-PRE-PROCESS cmd="exec-set" data="nodeid=(echo ${NODEID:-{{NODEID}}})"/>
  <X-PRE-PROCESS cmd="exec-set" data="loglevel=(echo ${LOGLEVEL:-INFO})"/>
  <X-PRE-PROCESS cmd="exec-set" data="eslhost=(echo ${ESLHOST:-{{eslhost}}})"/>
  <X-PRE-PROCESS cmd="exec-set" data="eslport=(echo ${ESLPOST:-{{eslport}}})"/>
  <X-PRE-PROCESS cmd="exec-set" data="eslpassword=(echo ${ESLPASSWORD:-{{eslpassword}}})"/>
  <X-PRE-PROCESS cmd="set" data="hold_music={loops=-1}tone_stream://%(250,0,350);%(250,0,440);%(250,0,530);%(300,0,700);%(400,0,800);%(300,0,900);%(250,0,600);%(160,0,440)"/>
  <X-PRE-PROCESS cmd="set" data="devshm=/dev/shm"/>
  <!-- BEGIN: CONFIGURATION SECTION -->
  <section name="configuration" description="Various Configuration">
    <!-- ACL ACCESS CONTROL LIST -->
    <configuration name="acl.conf" description="Network Lists">
      <network-lists>
        <X-PRE-PROCESS cmd="exec" data="curl -so $${devshm}/acl $${fsxmlapi}/acl"/>
        <X-PRE-PROCESS cmd="include" data="$${devshm}/acl"/>
        <list name="loopback.auto" default="deny">
          <node type="allow" cidr="127.0.0.1/32"/>
          <node type="allow" cidr="::1/128"/>
       </list>
      </network-lists>
    </configuration>
    <!-- CONSOLE LOGGER -->
    <configuration name="console.conf" description="Console Logger">
      <mappings>
        <map name="all" value="console,debug,info,notice,warning,err,crit,alert"/>
      </mappings>
      <settings>
        <param name="colorize" value="false"/>
        <param name="loglevel" value="$${loglevel}"/>
      </settings>
    </configuration>
    <!-- DISTRIBUTOR -->
    <configuration name="distributor.conf" description="Distributor Configuration">
      <lists>
        <X-PRE-PROCESS cmd="exec" data="curl -so $${devshm}/distributor $${fsxmlapi}/distributor"/>
        <X-PRE-PROCESS cmd="include" data="$${devshm}/distributor"/>
      </lists>
    </configuration>
    <!-- EVENT SOCKET -->
    <configuration name="event_socket.conf" description="Socket Client">
      <settings>
        <param name="nat-map" value="false"/>
        <param name="listen-ip" value="$${eslhost}"/>
        <param name="listen-port" value="$${eslport}"/>
        <param name="password" value="$${eslpassword}"/>
      </settings>
    </configuration>
    <!--- LOGFILE -->
    <configuration name="logfile.conf" description="File Logging">
      <settings>
        <param name="rotate-on-hup" value="true"/>
      </settings>
      <profiles>
        <profile name="default">
          <settings>
            <!-- At this length in bytes rotate the log file (0 for never) -->
            <param name="rollover" value="104857600"/>
            	<!-- Maximum number of log files to keep before wrapping -->
              <!-- If this parameter is enabled, the log filenames will not include a date stamp -->
              <param name="maximum-rotate" value="32"/>
            <param name="uuid" value="true" />
          </settings>
          <mappings>
            <map name="all" value="console,info,notice,warning,err,crit,alert"/>
          </mappings>
        </profile>
      </profiles>
    </configuration>
    <!--- AWESOME LUA -->
    <configuration name="lua.conf" description="LUA Configuration">
      <settings>
        <!-- <param name="module-directory" value="/usr/share/lua/5.2/?.lua"/> -->
        <param name="startup-script" value="callng/event.initiation.lua"/>
        <hook event="CHANNEL_CREATE" script="callng/event.capacity.lua"/>
        <hook event="CHANNEL_UUID" script="callng/event.capacity.lua"/>
        <hook event="CHANNEL_DESTROY" script="callng/event.capacity.lua"/>
        <hook event="CHANNEL_HANGUP_COMPLETE" script="callng/event.cdr.lua"/>
        <hook event="STARTUP" script="callng/event.startup.lua"/>
        <hook event="CUSTOM" subclass="sofia::register_failure" script="callng/event.unauth.lua"/>
      </settings>
    </configuration>
    <!--- MODULES -->
    <configuration name="pre_load_modules.conf" description="Modules">
      <modules>
        <load module="mod_pgsql"/>
      </modules>
    </configuration>
    <configuration name="modules.conf" description="Modules">
      <modules>
        <load module="mod_console"/>
        <load module="mod_logfile"/>
        <load module="mod_event_socket"/>
        <load module="mod_bcg729"/>
        <load module="mod_amr"/>
        <load module="mod_amrwb"/>
        <load module="mod_spandsp"/>
        <load module="mod_sndfile"/>
        <load module="mod_tone_stream"/>
        <load module="mod_opus"/>
        <load module="mod_flite"/>
        <load module="mod_lua"/>
        <load module="mod_sofia"/>
        <load module="mod_distributor"/>
        <load module="mod_commands"/>
        <load module="mod_dptools"/>
        <load module="mod_dialplan_xml"/>
      </modules>
    </configuration>
    <!--- CODECS -->
    <configuration name="amr.conf">
      <settings>
        <param name="default-bitrate" value="7"/>
        <param name="volte" value="1"/>
        <param name="adjust-bitrate" value="0"/>
        <param name="force-oa" value="0"/>
      </settings>
    </configuration>
    <configuration name="amrwb.conf">
      <settings>
        <param name="default-bitrate" value="8"/>
        <param name="volte" value="1"/>
        <param name="adjust-bitrate" value="0"/>
        <param name="force-oa" value="0"/>
        <param name="mode-set-overwrite" value="0"/>
      </settings>
    </configuration>
    <configuration name="opus.conf">
      <settings>
        <param name="use-vbr" value="1"/>
        <param name="use-dtx" value="1"/>
        <param name="complexity" value="10"/>
        <param name="packet-loss-percent" value="10"/>
        <param name="keep-fec-enabled" value="1"/>
        <param name="use-jb-lookahead" value="1"/>
        <param name="maxaveragebitrate" value="64000"/>
        <param name="maxplaybackrate" value="48000"/>
        <param name="sprop-maxcapturerate" value="48000"/>
        <param name="adjust-bitrate" value="1"/>
      </settings>
    </configuration>
    <!--- SOFIA SIP -->
    <configuration name="sofia.conf" description="sofia Endpoint">
      <global_settings>
        <param name="log-level" value="0"/>
        <param name="debug-presence" value="0"/>
      </global_settings>
      <profiles>
        <X-PRE-PROCESS cmd="exec" data="curl -so $${devshm}/sipsetting $${fsxmlapi}/sip-setting/$${nodeid}" />
        <X-PRE-PROCESS cmd="include" data="$${devshm}/sipsetting"/>
      </profiles>
    </configuration>
    <!--- SPANDSP  -->
    <configuration name="spandsp.conf" description="FAX application configuration">
    </configuration>
    <!-- FREESWITCH DEFAULT CONFIGURATION -->
    <configuration name="switch.conf" description="Core Configuration">
      <settings>
        <X-PRE-PROCESS cmd="exec" data="curl -so $${devshm}/switch $${fsxmlapi}/switch"/>
        <X-PRE-PROCESS cmd="include" data="$${devshm}/switch"/>
        <param name="switchname" value="$${nodeid}"/>
      </settings>
    </configuration>
  </section>
  <!-- END: CONFIGURATION SECTION -->
  <!-- BEGIN: DIALPLAN SECTION -->
  <section name="dialplan" description="Regex/XML Dialplan">
    <context name="redirected">
      <extension name="any_to_any">
        <condition field="destination_number" expression="^.+$">
          <action application="lua" data="callng/redirection.lua"/>
          <anti-action application="hangup" data="CALL_REJECTED"/>
        </condition>
      </extension>
    </context>
    <context name="carrier">
      <extension name="carrier_to_any">
        <condition regex="all">
          <action application="lua" data="callng/main.lua"/>
          <anti-action application="hangup" data="CALL_REJECTED"/>
          <anti-action application="log" data="WARNING: YOU SHOULD NOT FOUND THIS MESSAGE, SO PLEASE CHECK THE FIREWALL"/>
        </condition>
      </extension>
    </context>
    <context name="core">
      <extension name="core_to_any">
        <condition regex="all">
          <action application="lua" data="callng/main.lua"/>
          <anti-action application="hangup" data="CALL_REJECTED"/>
          <anti-action application="log" data="WARNING: YOU SHOULD NOT FOUND THIS MESSAGE, SO PLEASE CHECK THE FIREWALL"/>
        </condition>
      </extension>
    </context>
    <context name="access">
      <extension name="access_to_any">
        <condition regex="all">
          <!-- <regex field="${acl(${network_addr} ACL)}" expression="true"/> -->
          <action application="lua" data="callng/main.lua"/>
          <anti-action application="hangup" data="CALL_REJECTED"/>
          <anti-action application="log" data="WARNING: YOU SHOULD NOT FOUND THIS MESSAGE, SO PLEASE CHECK THE FIREWALL"/>
        </condition>
      </extension>
    </context>
  </section>
  <!-- END: DIALPLAN SECTION -->
  <!-- BEGIN: DIRECTORY SECTION -->
  <section name="directory" description="User Directory">
    <X-PRE-PROCESS cmd="exec" data="curl -so $${devshm}/directory $${fsxmlapi}/directory"/>
    <X-PRE-PROCESS cmd="include" data="$${devshm}/directory"/>
  </section>
  <!-- END: DIRECTORY SECTION -->
</document>

有几个关键点：

curl -so $${devshm}/acl $${fsxmlapi}/acl

通过请求main.py, 把获取的配置写入到/dev/shm/acl共享内存的文件中。
<X-PRE-PROCESS cmd="include" data="$${devshm}/acl"/>

include结合realodxml,可以实现动态更新配置。
<hook event="CHANNEL_CREATE" script="callng/event.capacity.lua"/>

实现了事件监听的效果。
<param name="startup-script" value="callng/event.initiation.lua"/>

服务启动就运行脚本。