TOPOS Module

Daniel-Constantin Mierla

Edited by

Daniel-Constantin Mierla

Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. storage (str)
3.2. db_url (str)
3.3. mask_callid (int)
3.4. sanity_checks (int)
3.5. branch_expire (int)
3.6. dialog_expire (int)
3.7. clean_interval (int)
3.8. event_callback (str)
4. Event Routes
4.1. event_route[topos:msg-outgoing]

List of Examples

1.1. Set storage parameter
1.2. Set db_url parameter
1.3. Set mask_callid parameter
1.4. Set sanity_checks parameter
1.5. Set branch_expire parameter
1.6. Set dialog_expire parameter
1.7. Set clean_interval parameter
1.8. Set event_callback parameter
1.9. Usage of event_route[topos:msg-outgoing]

Chapter 1. Admin Guide

1. Overview

This module offers topology hiding by stripping the SIP routing headers that show topology details. The script interpreter gets the SIP messages with full content, so all existing functionality is preserved.

The module is transparent for the configuration writer. It only needs to be loaded (tune the parameters if needed).

It also works for SIP MESSAGE or other requests that do not create a call dialog -- record_route() must be used for them as well, the headers are not going to be in the messages sent to the network, they are needed to know local addresses used to communicate with each side.

2. Dependencies

2.1. Kamailio Modules

The following modules must be loaded before this module:

  • rr module - server must perform record routing to ensure in-dialog requests are encoded/decoded (it must be done for all initial requests).

  • database module - to store the data for topology stripping and restoring.

2.2. External Libraries or Applications

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

  • none.

3. Parameters

3.1. storage (str)

Type of storage, valid types are:

  • db - Database Backend

  • redis - Redis Backend

Default value is db.

Example 1.1. Set storage parameter

modparam("topos", "storage", "redis")

3.2. db_url (str)

Database URL.

Default value is mysql://kamailio:kamailiorw@localhost/kamailio.

Example 1.2. Set db_url parameter

modparam("topos", "db_url", "dbdriver://username:password@dbhost/dbname")

3.3. mask_callid (int)

Note: this functionality is not implemented yet - the parameter is present in order to be in pair with topoh module.

Whether to replace or not the Call-ID with another unique id generated by Kamailio.

Default value is 0 (do not mask).

Example 1.3. Set mask_callid parameter

modparam("topos", "mask_callid", 1)

3.4. sanity_checks (int)

If set to 1, topos module will bind to sanity module in order to perform sanity checks over received SIP request. Default sanity checks are done. It is useful to check if received request is well formated before proceeding to encoding/decoding.

Default value is 0 (do not bind to sanity module).

Example 1.4. Set sanity_checks parameter

modparam("topos", "sanity_checks", 1)

3.5. branch_expire (int)

Interval in seconds after which the branch records are deleted.

Default value is 180 (3 min).

Example 1.5. Set branch_expire parameter

modparam("topos", "branch_expire", 300)

3.6. dialog_expire (int)

Interval in seconds after which the dialog records are deleted.

Default value is 10800 (3 hours).

Example 1.6. Set dialog_expire parameter

modparam("topos", "dialog_expire", 3600)

3.7. clean_interval (int)

Interval in seconds to run the clean up of stored records.

Default value is 60 (1 min).

Example 1.7. Set clean_interval parameter

modparam("topos", "clean_interval", 30)

3.8. event_callback (str)

The name of the function in the KEMI configuration file (embedded scripting language such as Lua, Python, ...) to be executed instead of event_route[...] blocks.

The function receives a string parameter with the name of the event.

Default value is 'empty' (no function is executed for events).

Example 1.8. Set event_callback parameter

modparam("topos", "event_callback", "ksr_topos_event")
-- event callback function implemented in Lua
function ksr_topos_event(evname)"===== topos module triggered event: " .. evname .. "\n");
	return 1;

4. Event Routes

4.1. event_route[topos:msg-outgoing]

It is executed before doing topology stripping processing for an outgoing SIP message. If 'drop' is executed inside the event route, then the module skips doing the topology hiding.

Inside the event route the variables $sndto(ip), $sndto(port) and $sndto(proto) point to the destination. The SIP message is not the one to be sent out, but an internally generated one at startup, to avoid reparsing the outgoing SIP message for the cases when topology hiding is not wanted.

Example 1.9. Usage of event_route[topos:msg-outgoing]

event_route[topos:msg-outgoing] {
  if($sndto(ip)=="") {