cfgutils Module

Henning Westerholt

   1und1 Internet AG
   <henning.westerholt@1und1.de>

Carsten Bock

   BASIS AudioNet GmbH

Elena-Ramona Modroiu

   rosdev.ro
   <ramona@rosdev.ro>

Sergio Gutierrez

   <saguti@gmail.com>

   Copyright © 2007, 2008 1und1 Internet AG, BASIS AudioNet GmbH,
   Elena-Ramona Modroiu
   Revision History
   Revision $Revision: 6109 $ $Date: 2009-07-21 10:45:05 +0300
                              (Tue, 21 Jul 2009) $
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. Dependencies
        1.3. Exported Parameters

              1.3.1. initial_probability (string)
              1.3.2. hash_file (string)
              1.3.3. shvset (string)
              1.3.4. varset (string)

        1.4. Exported Functions

              1.4.1. rand_event()
              1.4.2. rand_set_prob(probabiltiy)
              1.4.3. rand_reset_prob()
              1.4.4. rand_get_prob()
              1.4.5. sleep(time)
              1.4.6. usleep(time)
              1.4.7. abort()
              1.4.8. pkg_status()
              1.4.9. shm_status()
              1.4.10. set_count(pseudovarible_name)
              1.4.11. set_select_weight(pseudovarible_name)

        1.5. MI Commands

              1.5.1. rand_set_prop
              1.5.2. rand_reset_prob
              1.5.3. rand_get_prob
              1.5.4. check_config_hash
              1.5.5. get_config_hash
              1.5.6. shv_set
              1.5.7. shv_get

        1.6. Exported pseudo-variables

              1.6.1. $RANDOM
              1.6.2. $time(name)
              1.6.3. $shv(name)

   List of Examples

   1.1. initial_probability parameter usage
   1.2. hash_file parameter usage
   1.3. shvset parameter usage
   1.4. varset parameter usage
   1.5. rand_event() usage
   1.6. rand_set_prob() usage
   1.7. rand_reset_prob() usage
   1.8. rand_get_prob() usage
   1.9. sleep usage
   1.10. usleep usage
   1.11. abort usage
   1.12. pkg_status usage
   1.13. shm_status usage
   1.14. set_count usage
   1.15. set_count usage
   1.16. rand_set_prob usage
   1.17. rand_reset_prob usage
   1.18. rand_get_prob usage
   1.19. check_config_hash usage
   1.20. get_config_hash usage
   1.21. shv_set usage
   1.22. shv_get usage
   1.23. RANDOM pseudo-variable usage
   1.24. time(name) pseudo-variable usage
   1.25. shv(name) pseudo-variable usage

Chapter 1. Admin Guide

1.1. Overview

   Useful extensions for the server configuration.

   The cfgutils module can be used to introduce randomness to the
   behaviour of the server. It provides setup functions and the
   "rand_event" function. This function return either true or
   false, depending on a random value and a specified probability.
   E.g. if you set via fifo or script a probability value of 5%,
   then 5% of all calls to rand_event will return false. The
   pseudovariable "$RANDOM" could be used to introduce random
   values e.g. into a SIP reply.

   The benefit of this module is the probability of the decision
   can be manipulated by external applications such as web
   interface or command line tools. The probability must be
   specified as percent value, ranging from 0 to 100.

   The module exports commands to FIFO server that can be used to
   change the global settings via FIFO interface. The FIFO
   commands are: "set_prob", "reset_prob" and "get_prob".

   This module can be used for simple load-shedding, e.g. reply 5%
   of the Invites with a 503 error and a adequate random
   Retry-After value.

   The module provides as well functions to delay the execution of
   the server. The functions "sleep" and "usleep" could be used to
   let the server wait a specific time interval.

   It can also hash the config file used from the server with a
   (weak) cryptographic hash function on startup. This value is
   saved and can be later compared to the actual hash, to detect
   modifications of this file after the server start. This
   functions are available as the FIFO commands
   "check_config_hash" and "get_config_hash".

1.2. Dependencies

   The module depends on the following modules (in the other words
   the listed modules must be loaded before this module):
     * none

1.3. Exported Parameters

1.3.1. initial_probability (string)

   The initial value of the probability.

   Default value is "10".

   Example 1.1. initial_probability parameter usage

modparam("cfgutils", "initial_probability", 15)


1.3.2. hash_file (string)

   The config file name for that a hash value should be calculated
   on startup.

   There is no default value, is no parameter is given the hash
   functionality is disabled.

   Example 1.2. hash_file parameter usage

modparam("cfgutils", "hash_file", "/etc/opensips/opensips.cfg")


1.3.3. shvset (string)

   Set the value of a shared variable ($shv(name)). The parameter
   can be set many times.

   The value of the parameter has the format: _name_ '=' _type_
   ':' _value_
     * _name_: shared variable name
     * _type_: type of the value
          + "i": integer value
          + "s": string value
     * _value_: value to be set

   Default value is "NULL".

   Example 1.3. shvset parameter usage
...
modparam("cfgutils", "shvset", "debug=i:1")
modparam("cfgutils", "shvset", "pstngw=s:sip:10.10.10.10")
...

1.3.4. varset (string)

   Set the value of a script variable ($var(name)). The parameter
   can be set many times.

   The value of the parameter has the format: _name_ '=' _type_
   ':' _value_
     * _name_: shared variable name
     * _type_: type of the value
          + "i": integer value
          + "s": string value
     * _value_: value to be set

   Default value is "NULL".

   Example 1.4. varset parameter usage
...
modparam("cfgutils", "varset", "init=i:1")
modparam("cfgutils", "varset", "gw=s:sip:11.11.11.11;transport=tcp")
...

1.4. Exported Functions

1.4.1. rand_event()

   Return true or false, depending on a random value and a
   probability value.

   Example 1.5. rand_event() usage
...
if (rand_event()) {
  append_to_reply("Retry-After: 120\n");
  sl_send_reply("503", "Try later");
  exit;
};
# normal message processing follows
...

1.4.2. rand_set_prob(probabiltiy)

   Set the "probability" of the decision.

   "probability" can have a value from the range 0..99.

   Example 1.6. rand_set_prob() usage
...
rand_set_prob("4");
...

1.4.3. rand_reset_prob()

   Reset the probability back to the inital value.

   Example 1.7. rand_reset_prob() usage
...
rand_reset_prob();
...

1.4.4. rand_get_prob()

   Return the current probability setting, e.g. for logging
   purposes.

   Example 1.8. rand_get_prob() usage
...
rand_get_prob();


1.4.5.  sleep(time)

   Waits "time" seconds.

   Meaning of the parameters is as follows:
     * time - Time to wait in seconds. String may be a
       pseudovariable. In case that variable does not contain a
       numerical value, it is evaluated to zero seconds.

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE,
   FAILURE_ROUTE, BRANCH_ROUTE.

   Example 1.9. sleep usage
...
sleep("1");
...
$avp(s:secs)="10";
sleep("$avp(s:secs)");
...

1.4.6.  usleep(time)

   Waits "time" micro-seconds.

   Meaning of the parameters is as follows:
     * time - Time to wait in micro-seconds. The string may
       contain a pseudovariable. In case that pseudovar does not
       contain a numerical value, it is evaluated to zero seconds.

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE,
   FAILURE_ROUTE, BRANCH_ROUTE.

   Example 1.10. usleep usage
...
usleep("500000"); # sleep half of sec
...

1.4.7.  abort()

   Debugging function that aborts the server. Depending on the
   configuration of the server a core dump will be created.

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE,
   FAILURE_ROUTE, BRANCH_ROUTE.

   Example 1.11. abort usage
...
abort();
...

1.4.8.  pkg_status()

   Debugging function that dumps the status for the private (PKG)
   memory. This information is logged to the default log facility,
   depending on the general log level and the memlog setting. You
   need to compile the server with activated memory debugging to
   get detailed informations.

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE,
   FAILURE_ROUTE, BRANCH_ROUTE.

   Example 1.12. pkg_status usage
...
pkg_status();
...

1.4.9.  shm_status()

   Debugging function that dumps the status for the shared (SHM)
   memory. This information is logged to the default log facility,
   depending on the general log level and the memlog setting. You
   need to compile the server with activated memory debugging to
   get detailed informations.

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE,
   FAILURE_ROUTE, BRANCH_ROUTE.

   Example 1.13. shm_status usage
...
shm_status();
...

1.4.10.  set_count(pseudovarible_name)

   Function that counts the values of a pseudovariable. It makes
   sence to call this function only for pseudovariables that can
   take more values (avp, headers).

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE,
   FAILURE_ROUTE, BRANCH_ROUTE.

   Example 1.14. set_count usage
...
$avp(i:11) = set_count("$avp(i:10)");
...

1.4.11.  set_select_weight(pseudovarible_name)

   This function selects an element from a set formed by the
   values of the pseudovariable name given as parameter. It
   applies the genetic algorithm - roulette-wheel selection to
   choose an element from a set. The probability of selecting a
   certain element is proportionate with its weight. It will
   return the index of that selected element.

   This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE,
   FAILURE_ROUTE, BRANCH_ROUTE.

   Example 1.15. set_count usage
...
$avp(i:21) = set_select_weight("$avp(i:10)");
...

1.5. MI Commands

1.5.1. rand_set_prop

   Set the probability value to the given parameter. The parameter
   should be a percent value.

   The parameter value must be a number from 0 to 99.

   Example 1.16. rand_set_prob usage
...
$ opensipsctl fifo rand_set_prob 10
...

1.5.2. rand_reset_prob

   Reset the probability value to the inital start value.

   This command don't need a parameter.

   Example 1.17.  rand_reset_prob usage
...
$ opensipsctl fifo rand_reset_prob
...

1.5.3. rand_get_prob

   Return the actual probability setting.

   The function return the actual probability value.

   Example 1.18. rand_get_prob usage
...
$ opensipsctl fifo get_prob
The actual probability is 50 percent.
...

1.5.4. check_config_hash

   Check if the actual config file hash is identical to the stored
   one.

   The function returns 200 OK if the hash values are identical,
   400 if there are not identical, 404 if no file for hashing has
   been configured and 500 on errors. Additional a short text
   message is printed.

   Example 1.19. check_config_hash usage
...
$ opensipsctl fifo check_config_hash
The actual config file hash is identical to the stored one.
...

1.5.5. get_config_hash

   Return the stored config file hash.

   The function returns 200 OK and the hash value on success or
   404 if no file for hashing has been configured.

   Example 1.20. get_config_hash usage
...
$ opensipsctl fifo get_config_hash
1580a37104eb4de69ab9f31ce8d6e3e0
...

1.5.6. shv_set

   Set the value of a shared variable ($shv(name)).

   Parameters:
     * _name_: shared variable name
     * _type_: type of the value
          + "int": integer value
          + "str": string value
     * _value_: value to be set

   MI FIFO Command Format:
                :shv_set:_reply_fifo_file_
                _name_
                _type_
                _value_
                _empty_line_

   Example 1.21. shv_set usage
...
$ opensipsctl fifo shv_set debug int 0
...

1.5.7. shv_get

   Get the value of a shared variable ($shv(name)).

   Parameters:
     * _name_: shared variable name. If this parameter is missing,
       all shared variables are returned.

   MI FIFO Command Format:
                :shv_get:_reply_fifo_file_
                _name_
                _empty_line_

   Example 1.22. shv_get usage
...
$ opensipsctl fifo shv_get debug
$ opensipsctl fifo shv_get
...

1.6. Exported pseudo-variables

1.6.1. $RANDOM

   Returns a random value from the [0 - 2^31) range.

   Example 1.23. RANDOM pseudo-variable usage
...
if (get_random()) {
  $avp(i:10) = ($RANDOM / 16777216); # 2^24
  if ($avp(i:10) < 10) {
     $avp(i:10) = 10;
  }
  append_to_reply("Retry-After: $avp(i:10)\n");
  sl_send_reply("503", "Try later");
  exit;
};
# normal message processing follows


1.6.2. $time(name)

   The PV provides access to broken-down time attributes.

   The "name" can be:
     * sec - return seconds (int 0-59)
     * min - return minutes (int 0-59)
     * hour - return hours (int 0-23)
     * mday - return the day of month (int 0-59)
     * mon - return the month (int 1-12)
     * year - return the year (int, e.g., 2008)
     * wday - return the day of week (int, 1=Sunday - 7=Saturday)
     * yday - return the day of year (int, 1-366)
     * isdst - return daylight saving time status (int, 0 - DST
       off, >0 DST on)

   Example 1.24. time(name) pseudo-variable usage
...
if ($time(year) == 2008) {
        xlog("request: $rm from $fu to $ru in year 2008\n");
}
...

1.6.3. $shv(name)

   It is a class of pseudo-variables stored in shared memory. The
   value of $shv(name) is visible across all opensips processes.
   Each "shv" has single value and it is initialized to integer 0.
   You can use "shvset" parameter to initialize the shared
   variable. The module exports a set of MI functions to get/set
   the value of shared variables.

   Example 1.25. shv(name) pseudo-variable usage
...
modparam("cfgutils", "shvset", "debug=i:1")
...
if ($shv(debug) == 1) {
        xlog("request: $rm from $fu to $ru\n");
}
...
