# &adminguide;

## Overview

This module provides a way to get access to non-SIP packages received by &kamailio; via its SIP worker processes. The content of such packages is available in the $mb variable inside the event_route[nosip:msg].

Note that packets with size less than 32 bytes are discarded, this threshold being set to avoid handling the NAT keepalive packets coming from devices. The limit is planned to be made configurable. Also, by default &kamailio; writes a log messages in case of SIP parsing error, that can be controlled via 'corelog' global parameter.

Besides the content of the packet, $si and $sp provide the source IP and port, allowing to do filtering and authorization.

## Dependencies

### &kamailio; Modules

The following modules must be loaded before this module:

- none.

### External Libraries or Applications

The following libraries or applications must be installed before running &kamailio; with this module loaded:

- none

## Parameters

### `msg_match` (str)

Regular expression to match against content of the packet in order to execute the event_route[nosip:msg].

Default value is empty.

#### Set `msg_match` parameter

    ...
    modparam("nosip", "msg_match", "^KREQUEST-")
    ...

### `msg_skip` (str)

Regular expression to match against content of the packet in order to skip execution the event_route[nosip:msg].

Default value is empty.

#### Set `msg_match` parameter

    ...
    modparam("nosip", "msg_skip", "^GET ")
    ...

## Event Routes

### `event_route[nosip:msg]`

Event route block to be executed when a non-sip message is received by a SIP worker process.

The routename parameter can be a static string or a dynamic string value with config variables.

The sleep parameter represent the number of seconds to suspend the processing of a SIP request. Maximum value is 100. The parameter can be a static integer or a variable holding an integer.

Since the SIP request handling is resumed in another process, the config file execution state is practically lost. Therefore beware that the execution of config after resume will end once the route[routename] is finished.

This function can be used from REQUEST_ROUTE.

#### `event_route[nosip:msg]` usage

    ...
    loadmodule "nosip.so"
    ...
    event_route[nosip:msg] {
       xlog("non-sip packet received - content [[$mb]] from [$si:$sp]\n");
       exit;
    }
    ...

## Examples of Usage

There can be many useful cases when one wants to get a SIP worker back to handle a suspended SIP transaction. While this could be achieved via XMLRPC or HTTP for TCP workers, UDP workers are the least loaded in terms of network interaction layer (ie., there is no overhead for connections management like for TCP).

Parsing of the non-sip message can be done using config file actions: functions, expressions with variables and transformations.

Next is a basic example of parsing a message from the network and resuming the transaction.

### `event_route[nosip:msg]` use case

    ...
    # expect: :KREQUEST-RESUME-TRANSACTION:tindex:tlabel:routename:
    # example: :KREQUEST-RESUME-TRANSACTION:4242:8686:RESUME:
    loadmodule "nosip.so"
    ...
    event_route[nosip:msg] {
        xlog("non-sip packet received - content [[$mb]] from [$si:$sp]\n");

        # must be a trusted IP
        if($si!="127.0.0.1") {
            exit;
        }

        # validation of the format and resume transaction
        if($mb=~":KREQUEST-RESUME-TRANSACTION:[0-9]+:[0-9]+:[a-zA-Z0-9]+:$") {
            $var(tindex) = $(mb{s.select,1,:});
            $var(tlabel) = $(mb{s.select,2,:});
            $var(rname) = $(mb{s.select,3,:});
            t_continue("$var(tindex)", "$var(tlabel)", "$var(rname)");
        }
        exit;
    }

    route[RESUME] {
        ...
    }
    ...