Freeswitch自定义SIP头

• 添加自定义SIP头
  • diaplan中
  • lua脚本中
  • 实际效果
• 添加有对应信道变量的sip头
• 获取自定义sip头
  • diaplan中
  • lua脚本中
• 获取非自定义sip头

  Channel Variables

  Adding Request Headers

  You can add arbitrary headers to outbound SIP calls by prefixing the string ‘siph‘ to any channel variable, for example:

Note that for BYE requests, you will need to use the prefix ‘sipbye_h‘ on the channel variable.

While not required, you should prefix your headers with “X-“ to avoid issues with interoperability with other SIP stacks.
All inbound SIP calls will install any X- headers into local variables.
This means you can easily bridge any X- header from one FreeSWITCH instance to another.
To access the header above on a 2nd box, use the channel variable ${sip_h_X-Answer}
It is important to note that the syntax ${sip_h_custom-header} can’t be used to retrieve any custom header not starting with X-.
It is because Sofia only reads and puts into variables custom headers starting with X-.

Adding Response Headers

There are three types of response header prefixes that can be set:

• Response headersiprh
  
• Provisional response headersipph
  
• Bye response headersipbye_h
  

Each prefix will exclusively add headers for their given types of requests - there is no “global” response header prefix that will add a header to all response messages.
For example:

Adding Custom Headers

For instance, you may need P-Charge-Info to append to your INVITE header, you may do as follows:

Then, you would see it in SIP message:

折叠源码

Strip Individual SIP Headers

Sometimes a SIP provider will add extra header information. Most of the time they do that for their own use (tracking calls). But that extra information can cause a lot of problems. For example: I get a call from the PSTN via a DID provider (provider1). Since im not in the office the call gets bridged to my cell phone (provider2). Provider1 add’s extra information to the sip packet like displayed below:

In some scenario, we bridge this call directly to provider2 the calls get dropped since provider2 doesnt accept the X-voipnow header, so we have to strip off those SIP headers.
To strip them off, use the application UNSET in the dialplan (the inverse of SET):

Strip All custom SIP Headers

If you wish to strip all custom headers while keeping only those defined in dialplan:

Additional Channel variables

Additional variables may also be set to influence the way calls are handled by sofia.
For example, contacts can be filtered by setting the ‘sip_exclude_contact’ variable. Example:

Or you can perform SIP Digest authorization on outgoing calls by setting sip_auth_username and sip_auth_password variables to avoid using Gateways to authenticate. Example:

Changing the SIP Contact user FreeSWITCH normally uses mod_sofia@ip:port for the internal SIP contact. To change this to foo@ip:port, there is a variable, sip_contact_user:
{sip_contact_user=foo}sofia/my_profile/1234@192.168.0.1;transport=tcp

sip_renegotiate_codec_on_reinvite

true|false

sip_recovery_break_rfc

true|false

添加自定义SIP头

自定义头域必须使用X-前缀

diaplan中

<action application="set" data="sip_h_X-My-Heder=123456"/>
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lua脚本中

local my_header = "123456"
...
session:execute("set", "sip_h_X-My-Header=" .. my_header)
session:execute("export","sip_h_X-My-Header=" .. my_header)
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实际效果

在sip消息后续的传递过程中，抓取sip信令可以看到在sip消息的头域里面添加了如下的一行：

X-My-Header: 123456
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添加有对应信道变量的sip头

1. 修改方式和添加自定义sip头基本一致；
2. 可以通过将siph添加到任何通道变量前面来向出站sip添加任意标头；
3. 自定义sip头需要以X-为前缀，添加有对应信道变量的sip头不需要。

   此段描述引用自Freeswitch官网，没有经过测试 Adding Request Header部分

获取自定义sip头

获取sip头和获取信道变量相似

diaplan中

<action application="log" data="My Header: ${sip_h_X-My-Header}"/>
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lua脚本中

local my_header = session:getVariable("sip_h_X-My-Header")
freeswitch.consoleLog("info", "My Header: " .. my_header)
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获取非自定义sip头

暂时没有找到可以直接获取非自定义的sip头的方法，只能通过相关的信道变量来获取sip头的信息。