KeepAlive Module

Guillaume Bour

   <guillaume@bour.cc>

Edited by

Guillaume Bour

   <guillaume@bour.cc>

   Copyright © 2017 Guillaume Bour
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications
              2.3. Parameters

                    2.3.1. ping_interval (integer)
                    2.3.2. destination (string)

              2.4. Functions

                    2.4.1. is_alive(destination)

   2. Developer Guide

        1. Available Functions

              1.1. add_destination(uri, owner, flags, [callback,
                      [user_attr]])

              1.2. Examples

   List of Examples

   1.1. Set ping_interval parameter
   1.2. Set destination parameter
   1.3. is_alive() usage
   2.1. Loading KeepAlive module's API from another module, adding a
          destination to monitor & registering a callback

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications
        2.3. Parameters

              2.3.1. ping_interval (integer)
              2.3.2. destination (string)

        2.4. Functions

              2.4.1. is_alive(destination)

1. Overview

   This module performs destinations monitoring either for itself, or on
   the behalf of other modules. The monitoring is done by sending SIP
   OPTIONS requests, more or less in the same fashion as the dispatcher
   module (which was the initial source for this module).

   As an example of usage by other modules, see drouting, which was
   enhanced to use this module to monitor its gateways.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications
   2.3. Parameters

        2.3.1. ping_interval (integer)
        2.3.2. destination (string)

   2.4. Functions

        2.4.1. is_alive(destination)

2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * tm - Transaction module

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * none

2.3. Parameters

2.3.1. ping_interval (integer)

   Define the interval (in seconds) ping requests are sent to destinations

   Default value is 30 seconds.

   Example 1.1. Set ping_interval parameter
...
modparam("keepalive", "ping_interval", 10)
...

2.3.2. destination (string)

   Allows to statically define destinations you want to monitor

   Example 1.2. Set destination parameter
...
modparam("keepalive", "destination", "192.168.10.20")
modparam("keepalive", "destination", "sip.provider.com")
...

2.4. Functions

2.4.1.  is_alive(destination)

   Get destination status.

   The Parameter destination is destination you want to check status

   Returned value:
     * 1 if destination is up
     * 2 if destination is down
     * -1 on error

   This function can be used from ANY_ROUTE.

   Example 1.3. is_alive() usage
...
if(is_alive("192.168.10.20") == 1) {
  // do stuff
};
...

Chapter 2. Developer Guide

   Table of Contents

   1. Available Functions

        1.1. add_destination(uri, owner, flags, [callback, [user_attr]])
        1.2. Examples

   The KeepAlive module provides an internal API to be used by other
   Kamailio modules. This API offers support for destinations monitoring.

   For internal (non-script) usage, the KeepAlive module offers to other
   module the possibility to register callback functions to be executed
   for each destination's status change.

1. Available Functions

   1.1. add_destination(uri, owner, flags, [callback, [user_attr]])
   1.2. Examples

1.1.  add_destination(uri, owner, flags, [callback, [user_attr]])

   This function registers a new destination to monitor. Monitoring of the
   destination starts as soon as it returns with success (0 value).

   Meaning of the parameters is as follows:
     * uri (string) - address of destination to monitor. Valid format is
       [proto:]ip[:port], with:
          + proto being one of sip or sips (SIP over TLS). If omitted, sip
            is used by default
          + port being optional (using default standard port, 5060 for sip
            and 5061 for sips)
     * owner (string) - module name “owning” the destination (for
       information purpose)
     * flags (integer) - destination flags (unused for now, use 0 value)
     * callback (ka_statechanged_f, optional) - callback function,
       executed on destination's state change.
       The callback function is of type void (*ka_statechanged_f)(str
       *uri, int state, void *user_attr);. Use NULL to set no callback.
       destination's state value is one of:
          + 0 - unknown state (this is the destination state at first,
            waiting first ping replies or timeout)
          + 1 - destination is UP
          + 2 - destination is DOWN
     * user_attr (void * pointer, optional) - If callback function is
       setup, this parameter will be forwarded to it, as last parameter.
       Use NULL to set no user_attr parameter.

   Returned values:
     * 0 if ok
     * -1 if an error occurred

1.2. Examples

   Example 2.1. Loading KeepAlive module's API from another module, adding
   a destination to monitor & registering a callback
...
#include "../keepalive/api.h"
...
keepalive_api_t ka_api;
...
...
/* loading keepalive API */
if (bind_keepalive( &ka_api ) != 0) {
    LM_ERR("can't load KeepAlive API\n");
    goto error;
}
...
...
/* callback function */
void my_callback(str uri, int state, void *user_attr) {

        printf("%.*s new state is: %d\n", uri.len, uri.str, state)
}

/* register a new destination */
str dest  = str_init("sip:192.168.10.21:5060");
str owner = str_init("mymodule");

if (ka_api.add_destination(dest, owner, 0, my_callback, NULL) != 0) {
    LM_ERR("can't add destination\n");
    goto error;
}
...
