Options Module

Nils Ohlmeier

FhG Fokus

Edited by

Nils Ohlmeier

Revision History
Revision $Revision: 4594 $$Date: 2008-08-06 12:08:33 +0200 (Wed, 06 Aug 2008) $

Table of Contents

1. Admin Guide
1.1. Overview
1.2. Dependencies
1.2.1. Kamailio Modules
1.2.2. External Libraries or Applications
1.3. Exported Parameters
1.3.1. accept (string)
1.3.2. accept_encoding (string)
1.3.3. accept_language (string)
1.3.4. support (string)
1.4. Exported Functions
1.4.1. options_reply()

List of Examples

1.1. Set accept parameter
1.2. Set accept_encoding parameter
1.3. Set accept_language parameter
1.4. Set support parameter
1.5. options_reply usage

Chapter 1. Admin Guide

1.1. Overview

This module provides a function to answer OPTIONS requests which are directed to the server itself. This means an OPTIONS request which has the address of the server in the request URI, and no username in the URI. The request will be answered with a 200 OK which the capabilities of the server.

To answer OPTIONS request directed to your server is the easiest way for is-alive-tests on the SIP (application) layer from remote (similar to ICMP echo requests, also known as “ping”, on the network layer).

1.2. Dependencies

1.2.1. Kamailio Modules

The following modules must be loaded before this module:

  • sl -- Stateless replies.

1.2.2. External Libraries or Applications

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

  • None.

1.3. Exported Parameters

1.3.1. accept (string)

This parameter is the content of the Accept header field. Note: it is not clearly written in RFC3261 if a proxy should accept any content (the default “*/*”) because it does not care about content. Or if it does not accept any content, which is “”.

Default value is “*/*”.

Example 1.1. Set accept parameter

modparam("options", "accept", "application/*")

1.3.2. accept_encoding (string)

This parameter is the content of the Accept-Encoding header field. Please do not change the default value because Kamailio does not support any encodings yet.

Default value is “”.

Example 1.2. Set accept_encoding parameter

modparam("options", "accept_encoding", "gzip")

1.3.3. accept_language (string)

This parameter is the content of the Accept-Language header field. You can set any language code which you prefer for error descriptions from other devices, but presumably there are not much devices around which support other languages then the default English.

Default value is “en”.

Example 1.3. Set accept_language parameter

modparam("options", "accept_language", "de")

1.3.4. support (string)

This parameter is the content of the Support header field. Please do not change the default value, because Kamailio currently does not support any of the SIP extensions registered at the IANA.

Default value is “”.

Example 1.4. Set support parameter

modparam("options", "support", "100rel")

1.4. Exported Functions

1.4.1.  options_reply()

This function checks if the request method is OPTIONS and if the request URI does not contain an username. If both is true the request will be answered stateless with “200 OK” and the capabilities from the modules parameters.

It sends “500 Server Internal Error” for some errors and returns false if it is called for a wrong request.

The check for the request method and the missing username is optional because it is also done by the function itself. But you should not call this function outside the myself check because in this case the function could answer OPTIONS requests which are sent to you as outbound proxy but with an other destination then your proxy (this check is currently missing in the function).

This function can be used from REQUEST_ROUTE.

Example 1.5. options_reply usage

if (uri==myself) {
	if ((method==OPTIONS) && (! uri=~"sip:.*[@]+.*")) {