UAC_REDIRECT Module

Bogdan-Andrei Iancu

   Voice System

Edited by

Bogdan-Andrei Iancu

   Copyright © 2005 Voice Sistem
   Revision History
   Revision $Revision: 4630 $ $Date: 2008-08-06 12:08:33 +0200
                              (Mi, 06 Aug 2008) $
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. Accounting
        1.3. Dependencies

              1.3.1. Kamailio Modules
              1.3.2. External Libraries or Applications

        1.4. Exported Parameters

              1.4.1. default_filter (string)
              1.4.2. deny_filter (string)
              1.4.3. accept_filter (string)
              1.4.4. acc_function (string)
              1.4.5. acc_db_table (string)

        1.5. Exported Functions

              1.5.1. set_deny_filter(filter,flags)
              1.5.2. set_accept_filter(filter,flags)
              1.5.3. get_redirects(max)
              1.5.4. get_redirects(max,reason)

        1.6. Script Example

   List of Examples

   1.1. Set default_filter module parameter
   1.2. Set deny_filter module parameter
   1.3. Set accept_filter module parameter
   1.4. Set acc_function parameter
   1.5. Set acc_db_table parameter
   1.6. set_deny_filter usage
   1.7. set_accept_filter usage
   1.8. get_redirects usage
   1.9. get_redirects usage
   1.10. Redirection script example

Chapter 1. Admin Guide

1.1. Overview

   UAC REDIRECT - User Agent Client redirection - module enhance
   Kamailio with the functionality of being able to handle
   (interpret, filter, log and follow) redirect responses ( 3xx
   replies class).

   UAC REDIRECT module offer stateful processing, gathering the
   contacts from all 3xx branches of a call.

   The module provide a powerful mechanism for selecting and
   filtering the contacts to be used for the new redirect:
     * number based - limits like the number of total contacts to
       be used or the maximum number of contacts per branch to be
       selected.
     * Regular Expression based - combinations of deny and accept
       filters allow a strict control of the contacts to be used
       for redirection.

   When selecting from a 3xx branch the contacts to be used, the
   contacts will be ordered and prioritized based on the "q"
   value.

1.2. Accounting

   UAC REDIRECT module allows to log all the redirection (to be
   later used for CDR aggregation). This functionality may be
   dynamically enabled for each redirection situation.

   The logging will be done via the accounting module functions
   (all are supported). The information to be logged will be the
   same as the normal logged information directly via ACC module,
   but with following differences:
     * reason phrase - which will be dynamically set by the
       redirection function;
     * outgoing URI - which will be the redirect URI.

   For each redirect contact, a separate record will be logged.
   For example, if a call is redirected to three new contacts, the
   module will log three additional records corresponding to each
   redirect URI.

1.3. Dependencies

1.3.1. Kamailio Modules

   The following modules must be loaded before this module:
     * TM - Transaction Module, for accessing replies.
     * ACC - Accounting Module, but only if the logging feature is
       used.

1.3.2. External Libraries or Applications

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

1.4. Exported Parameters

1.4.1. default_filter (string)

   The default behavior in filtering contacts. It may be "accept"
   or "deny".

   The default value is "accept".

   Example 1.1. Set default_filter module parameter
...
modparam("uac_redirect","default_filter","deny")
...

1.4.2. deny_filter (string)

   The regular expression for default deny filtering. It make sens
   to be defined on only if the default_filter parameter is set to
   "accept". All contacts matching the deny_filter will be
   rejected; the rest of them will be accepted for redirection.

   The parameter may be defined only one - multiple definition
   will overwrite the previous definitions. If more regular
   expression need to be defined, use the set_deny_filter()
   scripting function.

   This parameter is optional, it's default value being NULL.

   Example 1.2. Set deny_filter module parameter
...
modparam("uac_redirect","deny_filter",".*@siphub\.net")
...

1.4.3. accept_filter (string)

   The regular expression for default accept filtering. It make
   sens to be defined on only if the default_filter parameter is
   set to "deny". All contacts matching the accept_filter will be
   accepted; the rest of them will be rejected for redirection.

   The parameter may be defined only one - multiple definition
   will overwrite the previous definitions. If more regular
   expression need to be defined, use the set_accept_filter()
   scripting function.

   This parameter is optional, it's default value being NULL.

   Example 1.3. Set accept_filter module parameter
...
modparam("uac_redirect","accept_filter",".*@siphub\.net")
...

1.4.4. acc_function (string)

   Specifies the accounting function to be used. Just be defining
   this parameter, the accounting support will not be enabled.
   Accounting may only be enabled via two parameters
   set_accept_filter() scripting function.

   Its values my be:
     * acc_log_request
     * acc_db_request
     * acc_rad_request
     * acc_diam_request

   The default value is "acc_log_request".

   Example 1.4. Set acc_function parameter
...
modparam("uac_redirect","acc_function","acc_db_request")
...

1.4.5. acc_db_table (string)

   Specifies the accounting table to be used if DB accounting was
   chosen (acc_function was set to "acc_db_request"). Just be
   defining this parameter, the accounting support will not be
   enabled. Accounting may only be enabled via two parameters
   set_accept_filter() scripting function.

   The default value is "acc".

   Example 1.5. Set acc_db_table parameter
...
modparam("uac_redirect","acc_db_table","acc_redirect")
...

1.5. Exported Functions

1.5.1.  set_deny_filter(filter,flags)

   Sets additional deny filters. Maximum 6 may be combined. This
   additional filter will apply only to the current message - it
   will not have a global effect.

   Default or previous added deny filter may be reset depending of
   the flag parameter value:
     * reset_all - reset both default and previous added deny
       filters;
     * reset_default - reset only the default deny filter;
     * reset_added - reset only the previous added deny filters;
     * empty - no reset, just add the filter.

   This function can be used from FAILURE_ROUTE.

   Example 1.6. set_deny_filter usage
...
set_deny_filter(".*@domain2.net","reset_all");
set_deny_filter(".*@domain1.net","");
...

1.5.2.  set_accept_filter(filter,flags)

   Sets additional accept filters. Maximum 6 may be combined. This
   additional filter will apply only to the current message - it
   will not have a global effect.

   Default or previous added deny filter may be reset depending of
   the flag parameter value:
     * reset_all - reset both default and previous added accept
       filters;
     * reset_default - reset only the default accept filter;
     * reset_added - reset only the previous added accept filters;
     * empty - no reset, just add the filter.

   This function can be used from FAILURE_ROUTE.

   Example 1.7. set_accept_filter usage
...
set_accept_filter(".*@domain2.net","reset_added");
set_accept_filter(".*@domain1.net","");
...

1.5.3.  get_redirects(max)

   The function may be called only from failure routes. It will
   extract the contacts from all 3xx branches and append them as
   new branches. Note that the function will not forward the new
   branches, this must be done explicitly from script.

   How many contacts (in total and per branch) are selected
   depends of the max parameter values. Its syntax is:
     * max = max_total [":" max_branch]
     * max_total = number of total contacts to be selected
     * max_branch = number of contacts per branch to be selected

   Both "max_total" and "max_branch" are positive integer. To
   specify unlimited values, use 0 value or "*" character.

   NOTE that during the selection process, each set of contacts
   from a specific branch are ordered based on "q" value.

   This function will produce no accounting records.

   This function can be used from FAILURE_ROUTE.

   Example 1.8. get_redirects usage
...
# max 2 contacts per branch, but no overall limit
get_redirects("*:2");
...
# no limits per branch, but not more than 6 overall contacts
get_redirects("6:*");
...
# no restrictions
get_redirects("*");
...

1.5.4.  get_redirects(max,reason)

   The function has same functionality as get_redirects(max)
   function, but it will produce accounting records.

   The accounting records will be mark by the reason phrase.

   If this function appears in the script, at startup, the module
   will import the accounting function. Otherwise not.

   This function can be used from FAILURE_ROUTE.

   Example 1.9. get_redirects usage
...
get_redirects("4:1","Redirected");
...

1.6. Script Example

   Example 1.10. Redirection script example
loadmodule "modules/sl/sl.so"
loadmodule "modules/usrloc/usrloc.so"
loadmodule "modules/registrar/registrar.so"
loadmodule "modules/tm/tm.so"
loadmodule "modules/acc/acc.so"
loadmodule "modules/uac_redirect/uac_redirect.so"

modparam("usrloc", "db_mode",   0)

route{
        if (uri==myself) {

                if (method=="REGISTER") {
                        save("location");
                        exit;
                };

                if (!lookup("location")) {
                        sl_send_reply("404", "Not Found");
                        exit;
                };
                # do redirect with accounting
                t_on_failure("2");
        } else {
                # just do redirect
                t_on_failure("1");
        }

        if (!t_relay()) {
                sl_reply_error();
        };
}

failure_route[1] {
        get_redirects("3:1");
        t_relay();
}

failure_route[2] {
        get_redirects("6:2","redirect");
        t_relay();
}
