mangler Module

Gabriel Vasile

FhG FOKUS

Edited by

Gabriel Vasile

Revision History
Revision $Revision: 5901 $$Date$

Table of Contents

1. Admin Guide
1.1. Overview
1.2. Dependencies
1.2.1. OpenSIPS Modules
1.2.2. External Libraries or Applications
1.3. Exported Parameters
1.3.1. contact_flds_separator (string)
1.4. Exported Functions
1.4.1. sdp_mangle_ip(pattern, newip)
1.4.2. sdp_mangle_port(offset)
1.4.3. encode_contact(encoding_prefix, public_ip)
1.4.4. decode_contact()
1.4.5. decode_contact_header()

List of Examples

1.1. Set db_url parameter
1.2. sdp_mangle_ip usage
1.3. sdp_mangle_port usage
1.4. encode_contact usage
1.5. decode_contact usage
1.6. decode_contact_header usage

Chapter 1. Admin Guide

1.1. Overview

This is a module to help with SDP mangling. Note: This module is obselete and will be removed for the 1.5.0 release.

1.2. Dependencies

1.2.1. OpenSIPS Modules

The following modules must be loaded before this module:

  • No dependencies on other OpenSIPS modules.

1.2.2. External Libraries or Applications

The following libraries or applications must be installed before running OpenSIPS with this module loaded:

  • None.

1.3. Exported Parameters

1.3.1. contact_flds_separator (string)

First char of this parameter is used as separator for encoding/decoding Contact header.

Warning

First char of this field must be set to a value which is not used inside username,password or other fields of contact. Otherwise it is possible for the decoding step to fail/produce wrong results.

Default value is *.

Example 1.1. Set db_url parameter

...
modparam("mangler", "contact_flds_separator", "-")
...

then an encoded uri might look sip:user-password-ip-port-protocol@PublicIP

1.4. Exported Functions

1.4.1.  sdp_mangle_ip(pattern, newip)

Changes IP addresses inside SDP package in lines describing connections like c=IN IP4 Currently in only changes IP4 addresses since IP6 probably will not need to traverse NAT :)

The function returns negative on error, or number of replacements + 1.

Meaning of the parameters is as follows:

  • pattern - A pair ip/mask used to match IP's located inside SDP package in lines c=IN IP4 ip. This lines will only be mangled if located IP is in the network described by this pattern. Examples of valid patterns are 10.0.0.0/255.0.0.0 or 10.0.0.0/8 etc.

  • newip - A string representing the new IP to be put inside SDP package if old IP address matches pattern.

This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE.

Example 1.2. sdp_mangle_ip usage

...
sdp_mangle_ip("10.0.0.0/8","193.175.135.38");
...

1.4.2.  sdp_mangle_port(offset)

Changes ports inside SDP package in lines describing media like m=audio 13451.

The function returns negative on error, or number of replacements + 1.

Meaning of the parameters is as follows:

  • offset - A string representing an integer which will be added/subtracted from the located port.

This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE.

Example 1.3. sdp_mangle_port usage

...
sdp_mangle_port("-12000");
...

1.4.3.  encode_contact(encoding_prefix, public_ip)

This function will encode uri-s inside Contact header in the following manner sip:username:password@ip:port;transport=protocol goes sip:enc_pref*username*ip*port*protocol@public_ip * is the default separator.

The function returns negative on error, 1 on success.

Meaning of the parameters is as follows:

  • encoding_prefix - Something to allow us to determine that a contact is encoded publicip--a routable IP, most probably you should put your external IP of your NAT box.

    public_ip - The public IP which will be used in the encoded contact, as described by the example above.

This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE.

Example 1.4. encode_contact usage

...
if ($si == 10.0.0.0/8) encode_contact("enc_prefix","193.175.135.38"); 
...

1.4.4.  decode_contact()

This function will decode the URI in first line in packets which come with encoded URI in the following manner sip:enc_pref*username*ip*port*protocol@public_ip goes to sip:username:password@ip:port;transport=protocol It uses the default set parameter for contact encoding separator.

The function returns negative on error, 1 on success.

Meaning of the parameters is as follows:

This function can be used from REQUEST_ROUTE.

Example 1.5. decode_contact usage

...
if ($ru =~ "^enc*") { decode_contact(); }
...

1.4.5.  decode_contact_header()

This function will decode URIs inside Contact header in the following manner sip:enc_pref*username*ip*port*protocol@public_ip goes to sip:username:password@ip:port;transport=protocol. It uses the default set parameter for contact encoding separator.

The function returns negative on error, 1 on success.

Meaning of the parameters is as follows:

This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE.

Example 1.6. decode_contact_header usage

...
if ($ru =~ "^enc*") { decode_contact_header(); }
...