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kamailio path模块

背景

path 模块的主要功能是在REGISTER请求中添加Path头, 这样在后续拨打该注册用户时，可以找到回去的路径。

官方文档地址: path, path的rfc文档为: path的rfc3327

本次测试的版本为:

version: kamailio 5.8.5 (x86_64/linux)

参数解析 

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# 将会使用第一个Route的received参数作为目的URI
modparam("path", "use_received", 1)
# 这个received的参数要和alias的参数保持一致
modparam("path", "received_format", 1)
# 设置received的名称
modparam("path", "received_name", "rcv")
# 会添加两个Path头,一个PATH的头是进来的网络socket,另一个是出去的网络socket。
modparam("path", "enable_r2", 1)
# 这个Path的uri会包含sn的参数
modparam("path", "sockname_mode", 1)

重要函数

add_path()

添加Path头, 这个URI为outgoing的地址

add_path(user)

添加Path头, 设置URI的用户为user

add_path(user, parameters)

添加Path头, 设置URI的用户为user, 并添加parameters参数。

add_path_received()

添加received参数到Path。

add_path_received(user)

添加received参数到Path, 并设置用户为user。

add_path_received(user, parameters)

添加received参数到Path, 并设置用户为user, 并添加parameters参数。

实战

配置示例 

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listen=udp:172.16.4.111:5461

loadmodule "stun.so"
loadmodule "outbound.so"
loadmodule "path.so"

modparam("path", "use_received", 1)
modparam("path", "received_format", 1)
#modparam("path", "enable_r2", 1)
modparam("path", "sockname_mode", 1)

...

route[REGISTRAR] {
        if (!is_method("REGISTER")) return;

        if(isflagset(FLT_NATS)) {
                setbflag(FLB_NATB);
#!ifdef WITH_NATSIPPING
                # do SIP NAT pinging
                setbflag(FLB_NATSIPPING);
#!endif
        }
        fix_nated_contact();
        if (!save("location","0x02")) {
        #if (!save("location")) {
                sl_reply_error();
        }

        $fs="udp:172.16.4.111:5461";
        $du="sip:172.16.4.114:5060";
        add_path();
        #msg_apply_changes();
        #assign_hf_value("Contact", "<sip:$fU@172.16.4.111:5461>;expires=120");
        #msg_apply_changes();
        route(RELAY);
        exit;
}

测试

测试场景

场景

此种情况下，注册sip信令图：

sip

不修改Contact头

  1. 软电话1005发出的REGISTER到kamailio的请求信息为:
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2025/08/07 10:54:41.399376 172.16.80.13:59393 -> 172.16.4.111:5461
REGISTER sip:172.16.4.111:5461 SIP/2.0
Via: SIP/2.0/UDP 172.16.80.13:59393;rport;branch=z9hG4bKPj77f2c0f3baa14df98ab811dd0e6a132b
Max-Forwards: 70
From: <sip:1005@172.16.4.111>;tag=1c4f54303f984e3bbaf7825c43e5eee4
To: <sip:1005@172.16.4.111>
Call-ID: 647cb3bee39541c8ad4491d749e727fc
CSeq: 18516 REGISTER
User-Agent: MicroSIP/3.21.6
Contact: <sip:1005@172.16.80.13:59393;ob>
Expires: 200
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, SUBSCRIBE, NOTIFY, REFER, MESSAGE, OPTIONS
Authorization: Digest username="1005", realm="172.16.4.111", nonce="be470993-7965-415f-b466-e94c2ddab774", uri="sip:172.16.4.111:
61", response="394b758a1f68f04af2998d17a59c2e96", algorithm=MD5, cnonce="0d405a7726f2402e8c9db4e3cc694603", qop=auth, nc=00000001
Content-Length:  0
  1. kamailio转发REGISTER:
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2025/08/07 10:54:41.399817 172.16.4.111:5461 -> 172.16.4.114:5060
REGISTER sip:172.16.4.111:5461 SIP/2.0
Via: SIP/2.0/UDP 172.16.4.111:5461;branch=z9hG4bK7294.4630172030dfbcb1018abcde74766f45.0
Via: SIP/2.0/UDP 172.16.80.13:59393;received=172.16.80.13;rport=59393;branch=z9hG4bKPj77f2c0f3baa14df98ab811dd0e6a132b
Max-Forwards: 69
From: <sip:1005@172.16.4.111>;tag=1c4f54303f984e3bbaf7825c43e5eee4
To: <sip:1005@172.16.4.111>
Call-ID: 647cb3bee39541c8ad4491d749e727fc
CSeq: 18516 REGISTER
User-Agent: MicroSIP/3.21.6
Contact: <sip:1005@172.16.80.13:59393;ob>
Expires: 200
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, SUBSCRIBE, NOTIFY, REFER, MESSAGE, OPTIONS
Authorization: Digest username="1005", realm="172.16.4.111", nonce="be470993-7965-415f-b466-e94c2ddab774", uri="sip:172.16.4.111:
61", response="394b758a1f68f04af2998d17a59c2e96", algorithm=MD5, cnonce="0d405a7726f2402e8c9db4e3cc694603", qop=auth, nc=00000001
Content-Length:  0

此时Contact为:<sip:1005@172.16.80.13:59393;ob>

  1. freeswitch中的注册信息:
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Call-ID:        647cb3bee39541c8ad4491d749e727fc
User:           1005@172.16.4.114
Contact:        "" <sip:1005@172.16.80.13:59393;ob>
Agent:          MicroSIP/3.21.6
Status:         Registered(UDP)(unknown) EXP(2025-08-07 10:57:59) EXPSECS(137)
Ping-Status:    Reachable
Ping-Time:      0.00
Host:           fs
IP:             172.16.4.111
Port:           5461
Auth-User:      1005
Auth-Realm:     172.16.4.111
MWI-Account:    1005@172.16.4.114
  1. 使用1008拨打1005的信令图：

sip

可以看到INVITE的Request-URI就是1005注册信息中的Contact。 此时这个请求透过了kamailio。

修改Contact头

放开注释:

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msg_apply_changes();
assign_hf_value("Contact", "<sip:$fU@172.16.4.111:5461>;expires=120");
  1. 软电话1005发出的REGISTER到kamailio的请求信息为:
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2025/08/07 11:07:04.155172 172.16.80.13:59393 -> 172.16.4.111:5461
REGISTER sip:172.16.4.111:5461 SIP/2.0
Via: SIP/2.0/UDP 172.16.80.13:59393;rport;branch=z9hG4bKPj3c4917ead53c4a649e796e7bb26c1779
Max-Forwards: 70
From: <sip:1005@172.16.4.111>;tag=de351588eb384435b10b45196b4040b9
To: <sip:1005@172.16.4.111>
Call-ID: 57b5c50d07b14706b046df403e99da99
CSeq: 37388 REGISTER
User-Agent: MicroSIP/3.21.6
Contact: <sip:1005@172.16.80.13:59393;ob>
Expires: 200
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, SUBSCRIBE, NOTIFY, REFER, MESSAGE, OPTIONS
Authorization: Digest username="1005", realm="172.16.4.111", nonce="f951f7e5-c53e-46f8-bfa5-ad6ff146ccc9", uri="sip:172.16.4.111:
61", response="d4d6608c547f105e00cacd4dd3820ad4", algorithm=MD5, cnonce="cf45cd14e34d435f994cdc1f82acb62d", qop=auth, nc=00000001
Content-Length:  0
  1. kamailio转发REGISTER:
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2025/08/07 11:07:04.156456 172.16.4.111:5461 -> 172.16.4.114:5060
REGISTER sip:172.16.4.111:5461 SIP/2.0
Via: SIP/2.0/UDP 172.16.4.111:5461;branch=z9hG4bK804c.e67315908cbc104f4f519092f4d97ecb.0
Via: SIP/2.0/UDP 172.16.80.13:59393;received=172.16.80.13;rport=59393;branch=z9hG4bKPj3c4917ead53c4a649e796e7bb26c1779
Max-Forwards: 69
From: <sip:1005@172.16.4.111>;tag=de351588eb384435b10b45196b4040b9
To: <sip:1005@172.16.4.111>
Call-ID: 57b5c50d07b14706b046df403e99da99
CSeq: 37388 REGISTER
User-Agent: MicroSIP/3.21.6
Contact: <sip:1005@172.16.4.111:5461>;expires=120
Expires: 200
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, SUBSCRIBE, NOTIFY, REFER, MESSAGE, OPTIONS
Authorization: Digest username="1005", realm="172.16.4.111", nonce="f951f7e5-c53e-46f8-bfa5-ad6ff146ccc9", uri="sip:172.16.4.111:
61", response="d4d6608c547f105e00cacd4dd3820ad4", algorithm=MD5, cnonce="cf45cd14e34d435f994cdc1f82acb62d", qop=auth, nc=00000001
Content-Length:  0

可以看到Contact变成了<sip:1005@172.16.4.111:5461>;expires=120

  1. freeswitch中的注册信息:
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Call-ID:        57b5c50d07b14706b046df403e99da99
User:           1005@172.16.4.114
Contact:        "" <sip:1005@172.16.4.111:5461>
Agent:          MicroSIP/3.21.6
Status:         Registered(UDP)(unknown) EXP(2025-08-07 11:07:07) EXPSECS(128)
Ping-Status:    Reachable
Ping-Time:      0.00
Host:           fs
IP:             172.16.4.111
Port:           5461
Auth-User:      1005
Auth-Realm:     172.16.4.111
MWI-Account:    1005@172.16.4.114
  1. 使用1008拨打1005的信令图：

sip

可以看到INVITE的Request-URI就是1005注册信息中的Contact。 先不管是否拨打成功，但是这个修改是我们需要的。

使用add_path

放开注释:

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add_path();
  1. 软电话1005发出的REGISTER到kamailio的请求信息为:
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2025/08/07 11:13:29.926084 172.16.80.13:59393 -> 172.16.4.111:5461
REGISTER sip:172.16.4.111:5461 SIP/2.0
Via: SIP/2.0/UDP 172.16.80.13:59393;rport;branch=z9hG4bKPj734f2bbe803b4b7b8c7da61c7cae8121
Max-Forwards: 70
From: <sip:1005@172.16.4.111>;tag=60b64f9e189d4b73973b95640e5c1894
To: <sip:1005@172.16.4.111>
Call-ID: ca33e9a8ff504a0d9e7aa0ebd558dc32
CSeq: 28980 REGISTER
User-Agent: MicroSIP/3.21.6
Contact: <sip:1005@172.16.80.13:59393;ob>
Expires: 200
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, SUBSCRIBE, NOTIFY, REFER, MESSAGE, OPTIONS
Authorization: Digest username="1005", realm="172.16.4.111", nonce="19ab3d8a-f754-48eb-b964-382a4ea6bb2a", uri="sip:172.16.4.111:
61", response="5feb7261cfafb500baa1c72efc942aa5", algorithm=MD5, cnonce="1abc1ff721484c69b50097870f1f445c", qop=auth, nc=00000001
Content-Length:  0
  1. kamailio转发REGISTER:
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2025/08/07 11:14:35.168348 172.16.4.111:5461 -> 172.16.4.114:5060
REGISTER sip:172.16.4.111:5461 SIP/2.0
Via: SIP/2.0/UDP 172.16.4.111:5461;branch=z9hG4bK3ebc.e457de15226712c7162a35cacec1aa9a.0
Via: SIP/2.0/UDP 172.16.80.13:59393;received=172.16.80.13;rport=59393;branch=z9hG4bKPjb2b73fc8e50849a5ae4aa5e71bb7c2ca
Max-Forwards: 69
From: <sip:1005@172.16.4.111>;tag=62cbc4d210e245d5b7b8bdb733825fb5
To: <sip:1005@172.16.4.111>
Call-ID: f5fbf048dd164736a91b0b8558d518e7
CSeq: 46523 REGISTER
User-Agent: MicroSIP/3.21.6
Contact: <sip:1005@172.16.80.13:59393;ob>
Expires: 200
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, SUBSCRIBE, NOTIFY, REFER, MESSAGE, OPTIONS
Authorization: Digest username="1005", realm="172.16.4.111", nonce="c8884fe9-cac0-4cf0-ab70-4f4a5f9588ef", uri="sip:172.16.4.111:
61", response="b605239c7eadc7ac5476e9e6072e615e", algorithm=MD5, cnonce="e1f085bbf949401980c867444c03f104", qop=auth, nc=00000001
Content-Length:  0
Path: <sip:172.16.4.111:5461;lr>

可以看到Contact没变，但是Path添加了<sip:172.16.4.111:5461;lr>。

  1. freeswitch中的注册信息:
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Call-ID:        f5fbf048dd164736a91b0b8558d518e7
User:           1005@172.16.4.114
Contact:        "" <sip:1005@172.16.80.13:59393;ob;fs_path=sip%3A172.16.4.111%3A5461%3Blr>
Agent:          MicroSIP/3.21.6
Status:         Registered(UDP)(unknown) EXP(2025-08-07 11:14:38) EXPSECS(177)
Ping-Status:    Reachable
Ping-Time:      0.00
Host:           fs
IP:             172.16.4.111
Port:           5461
Auth-User:      1005
Auth-Realm:     172.16.4.111
MWI-Account:    1005@172.16.4.114

新增了fs_path=sip%3A172.16.4.111%3A5461%3Blr。

  1. 使用1008拨打1005的信令图： sip

可以看到Request-URI为sip:1005@172.16.80.13:59393,但是发送请求到172.16.4.111:5461。 还添加了Route头为:172.16.4.111:5461。

总结

当我们使用kamailio用作注册服务器时，一方面可以通过修改REGISTER中的Contact达到后续的请求转发到kamailio, 另一方面可以通过add_path添加Path头，达到此目的，当然前提是被注册的服务器要支持path。

  1. Path是在发送INVITE请求给注册的用户时，能往回发送INVITE请求到注册的路径。
  2. Record-Route是在建立INVITE会话接通之后，信令找回的路径。
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