How to decode SIP methods stored by openSIPs?

Posted on: 2009-10-14 | Categories: Uncategorized

Well behaved SIP phone should present a list of supported methods (INVITE, MESSAGE, REFER etc.) in “Allow” header when registering with the proxy. This is saved in “methods” column in “location” table by openSIPs. Unfortunately this value is a bitmas so it is not so friendly to look at. The definition of each method (corresponding bit in the mask) can be found in parser/msg_parser.h around line 67.

For example 7999 represents 4096 + 2048 + 1024 + 512 + 256 + 32 + 16 + 8 + 4 +2 +1 which translates to the following methods: REFER, PRACK, NOTIFY, SUBSCRIBE, MESSAGE, OPTIONS, INFO, BYE , ACK, CANCEL, INVITE.

However you might need (as we did) to decode methods supported by registered phone with a PHP code. Below is a sniped which allows for just that:

<?php

$mask = 7999;

$methods = array (

“0” => “UNDEF”,    /* 0 – — */
“1” => “INVITE”,    /* 1 – 2^0 */
“2” => “CANCEL”,     /* 2 – 2^1 */
“4” => “ACK”,     /* 3 – 2^2 */
“8” => “BYE”,     /* 4 – 2^3 */
“16” => “INFO”,     /* 5 – 2^4 */
“32” => “OPTIONS”,     /* 6 – 2^5 */
“64” => “UPDATE”,     /* 7 – 2^6 */
“128” => “REGISTER”,     /* 8 – 2^7 */
“256” => “MESSAGE”,     /* 9 – 2^8 */
“512” => “SUBSCRIBE”,     /* 10 – 2^9 */
“1024” => “NOTIFY”,     /* 11 – 2^10 */
“2048” => “PRACK”,     /* 12 – 2^11 */
“4096” => “REFER”,     /* 13 – 2^12 */
“8192” => “PUBLISH”,     /* 14 – 2^13 */
“16384” => “OTHER”    /* 15 – 2^14 */ );

$supported = ”;

foreach ($methodsas$id => $method) {
   if ($id & $mask) {      $supported.= $method.“, “;    }
}
echo“Supported methods: $supported”;
?>

Hope it might help someone when integrating openSIPs with a web application.