1. Options Module

Nils Ohlmeier

   FhG Fokus

   Copyright © 2003 FhG Fokus
     __________________________________________________________________

   1.1. Overview
   1.2. Dependencies
   1.3. Parameters

        1.3.1. accept (string)
        1.3.2. accept_encoding (string)
        1.3.3. accept_language (string)
        1.3.4. supported (string)
        1.3.5. contact (string)
        1.3.6. contact_param (string)

   1.4. Functions

        1.4.1. options_reply()

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

   The following modules must be loaded before this module:
     * sl - Stateless replies.

1.3. 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. 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 SER does not support any
   encodings yet.

   Default value is "".

   Example 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 3. Set accept_language parameter
...
modparam("options", "accept_language", "de")
...

1.3.4. supported (string)

   This parameter is the content of the Supported header field Here you
   can enter the extensions which are supported by your SER config.
   Normally you should only use values here which are registered with the
   IANA.

   Default value is "".

   Example 4. Set supported parameter
...
modparam("options", "supported", "100rel")
...

1.3.5. contact (string)

   The content of this parameter will be inserted into the reply as the
   URI of the Contact header. If this parameter is empty (default case)
   then no Contact header in included in the reply. If this parameter is
   set to "dstip" the reply contains a Contact header with the IP, port
   and transport of the socket where the request was sent to. If this
   parameter is set to "ruri" the reply contains a Contact header with the
   same URI as the request URI of the original OPTIONS request.

   Default value is "".

   Example 5. Set contact parameter
...
modparam("options", "contact", "example.com")
...

1.3.6. contact_param (string)

   This parameter is appended to the value of the Contact header is case
   it is set. If just this parameter is set but the contact module
   parameter not, then the contact parameter is automatically set to
   dstip.

   Default value is "".

   Example 6. Set contact_param parameter
...
modparam("options", "contact_param", "lr=on")
...

1.4. 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).

   Example 7. options_reply usage
...
if (uri==myself) {
  if ((method==OPTIONS) && (! uri=~"sip:.*[@]+.*")) {
    options_reply();
  }
}
...