---
title: "cfgutils Module"
description: "Useful extensions for the server configuration."
---

## Admin Guide


### 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".


### Dependencies


The module depends on the following modules (in the other words the
listed modules must be loaded before this module):


- *none*


### Exported Parameters


#### initial_probability (string)


The initial value of the probability.


*Default value is "10".*


```opensips title="initial_probability parameter usage"
   
modparam("cfgutils", "initial_probability", 15)
   
```


#### 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.


```opensips title="hash_file parameter usage"
   
modparam("cfgutils", "hash_file", "/etc/opensips/opensips.cfg")
   
```


#### shv_hash_size (integer)


The size of the hash table used to store the shared variables ($shv).


*Default value is "64".*


```opensips title="shv_hash_size parameter usage"
modparam("cfgutils", "shv_hash_size", 1024)
```


#### 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".*


```opensips title="shvset parameter usage"
...
modparam("cfgutils", "shvset", "debug=i:1")
modparam("cfgutils", "shvset", "pstngw=s:sip:10.10.10.10")
...
```


#### 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".


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


#### lock_pool_size (integer)


The number of dynamic script locks to be allocated at OpenSIPS startup. This
number must be a power of 2. (i.e. 1, 2, 4, 8, 16, 32, 64 ...)


Note that the *lock_pool_size* parameter only affects
the number of dynamic locks created at startup. The pool of static locks
only depends on the number of unique static strings supplied throughout
the script to the set of static lock functions.


*Default value is "32".*


```opensips title="Setting lock_pool_size module parameter"
modparam("cfgutils", "lock_pool_size", 64)
```


### Exported Functions


#### rand_event([probability])


Generates a random floating point value between 0 - 100 and returns
true if the value is less or equal to the currently set probability.
If "probability" parameter is given, it will
override the global parameter set by [rand set prob](#rand_set_probprobability).


Parameters:


- probability (int, optional) - probability override


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


#### rand_set_prob(probability)


Set the "probability" of the decision.


Parameters:


- probability (int) - number ranging from 0 - 99, inclusively


```opensips title="rand_set_prob() usage"
...
rand_set_prob(4);
...
```


#### rand_reset_prob()


Reset the probability back to the
[initial probability](#initial_probability-string) value.


```opensips title="rand_reset_prob() usage"
...
rand_reset_prob();
...
```


#### rand_get_prob()


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


```opensips title="rand_get_prob() usage"
...
rand_get_prob();
   
```


#### sleep(time)


Waits "time" seconds.


Meaning of the parameters is as follows:


- *time (int)* - time to wait in seconds


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


```opensips title="sleep usage"
...
sleep(1);
...
$var(secs) = 10;
sleep($var(secs));
...
			
```


#### usleep(time)


Waits "time" micro-seconds.


Meaning of the parameters is as follows:


- *time (int)* - time to wait in micro-seconds


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


```opensips title="usleep usage"
...
usleep(500000); # sleep half a sec
...
			
```


#### 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.


```opensips title="abort usage"
...
abort();
...
			
```


#### 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.


```opensips title="pkg_status usage"
...
pkg_status();
...
			
```


#### 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.


```opensips title="shm_status usage"
...
shm_status();
...
			
```


#### set_count(var_to_count, ret_var)


Counts the number of values of a given variable.
It makes sense to call this function only for variables that can
take more values (AVPs, headers).


The result is returned in the second parameter.


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


```opensips title="set_count usage"
...
set_count($avp(dids), $var(num_dids));
...
			
```


#### set_select_weight(int_list_var)


This function selects an element from a set formed by the integer
values of the given "int_list_var" variable. 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.


```opensips title="set_select_weight usage"
...
$var(next_gw_idx) = set_select_weight($avp(gw_success_rates));
...
			
```


#### ts_usec_delta(t1_sec, t1_usec, t2_sec, t2_usec, [delta_str], [delta_int])


This function returns the absolute difference between the two given
timestamps. The result is expressed as *microseconds*
and can be returned as either string or integer.


**WARNING:** when using
*delta_int*, the function will return error code
**-1** in case the difference overflows
the signed integer holder! (i.e. a diff of ~35 minutes or more)


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


```opensips title="ts_usec_delta usage"
...
ts_usec_delta($var(t1s), 300, 10, $var(t2us), $var(diff_str));
...
			
```


#### check_time_rec(time_string, [timestamp])


The function returns a positive value if the specified time recurrence string
matches the current time, or a negative value otherwise.


For checking some other Unix timestamp than the current one, the second
parameter will contain the intended timestamp to check.


The syntax of each field is identical to the corresponding field from
RFC 2445.


This function may be used from any route.  It returns 1 on success
and -1, -2 or -3 on failure, parsing or internal errors, respectively.


Meaning of the parameters is as follows:


- *time_string (string)* - Time recurrence string which
will be matched against the current time. Its fields are separated by "|" and
the order in which they are given is: "timezone | dtstart | dtend | duration | freq
| until | interval | byday | bymday | byyday | byweekno | bymonth".
None of the fields following "freq" is used unless
"freq" is defined.  If the string ends in multiple null fields,
they can all be ommited.
The "timezone" field is optional.  It represents the timezone in
which to interpret the time recurrence elements (e.g. dtstart,
dtend, until).  By default, the system time zone is used.
- *timestamp (string, optional)* - A
specific Unix time to check.  The function simply expects the
actual Unix time here, there is no need to perform any timezone
adjustments.


Additionally, more complex time recurrence strings may be built by
connecting multiple time recurrence strings (described above) using
the logical AND ("&"), OR ("/") and NEG ("!") operators.
Furthermore, the expressions may be paranthesized.  Some examples:


- 20210104T080000|20211231T180000||WEEKLY|||MO,TU,WE,TH,FR
&
!20210104T120000|20211231T140000||WEEKLY|||MO,TU,WE,TH,FR
This example multi-recurrence expresses the working days schedule for
company X during 2021:  workdays from 8-18, except the 12-14 interval,
when everyone is out for lunch break and the business is closed.
Since the timezone is omitted from each schedule, the operating
system timezone will be used instead.
- America/New_York|20210104T090000|20210104T170000||WEEKLY|||MO,TU,WE,TH,FR
&
!(Europe/Amsterdam|20210427T000000|20210428T000000 / Europe/London|20211227T000000|20211228T000000)
This example multi-recurrence expresses the working days schedule for
US-based company Y during 2021:  workdays from 9-17 (NY timezone),
except european holidays such as King's Day (April 27th, NL) or
the Spring Bank Holiday (May 31st, UK), when most of its
workforce will have flown back to Europe.


```opensips title="check_time_rec usage"
...
# Only passing if still in 2012 and on a Bucharest-compatible timezone
if (check_time_rec("Europe/Bucharest|20120101T000000|20130101T000000"))
	xlog("Current system time matches the given Romanian time interval\n");
...
# Only passing if less than 30 days have passed from "dtstart", system timezone
if (check_time_rec("20121101T000000||p30d"))
	xlog("Current time matches the given interval\n");
...
			
```


#### get_static_lock(key)


Acquire the static lock which corresponds to "key".  In case the
lock is taken by another process, script execution will halt until the
lock is released.  Attempting to acquire the lock a second time by the
same process, without releasing it first, will result in a deadlock.


The static lock functions guarantee that two different strings will never
point to the same lock, thus avoiding introducing unnecessary
(and transparent!) synchronization between processes. Their disadvantage is
the nature of their parameters (static strings), making them inappropriate in
certain scenarios.


Meaning of the parameters is as follows:


- *key (static string)* - key to be hashed in
order to obtain the index of a static lock


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE, ONREPLY_ROUTE, 
BRANCH_ROUTE, LOCAL_ROUTE, STARTUP_ROUTE, TIMER_ROUTE, EVENT_ROUTE.


```opensips title="get_static_lock usage"
# acquire and release a static lock 
...
get_static_lock("Zone_1");
...
release_static_lock("Zone_1");
...
```


#### release_static_lock(key)


Release the static lock corresponding to "key". Nothing will happen if
the lock is not acquired.


Meaning of the parameters is as follows:


- *key (static string)* - key to be hashed in
order to obtain the index of a static lock.


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE, ONREPLY_ROUTE, 
BRANCH_ROUTE, LOCAL_ROUTE, STARTUP_ROUTE, TIMER_ROUTE|EVENT_ROUTE.


```opensips title="release_static_lock usage"
# acquire and release a static lock 
...
get_static_lock("Zone_1");
...
release_static_lock("Zone_1");
...
```


#### get_dynamic_lock(key)


Acquire the dynamic lock corresponding to "key".  In case the lock is
taken by another process, script execution will halt until the lock is
released.  Attempting to acquire the lock a second time by
the same process, without releasing it first, will result in a deadlock.


The dynamic lock functions have the advantage of allowing string
variables to be given as parameters, but the drawback to this is that
two strings may have the same hashed value, thus pointing to the same lock.
As a consequence, either two totally separate regions of the script will be
synchronized (they will not execute in parallel), or a process could end up
in a deadlock by acquiring two locks in a row on two different (but equally
hashed) strings. To address the latter issue, use the
[strings share lock](#strings_share_lockkey1-key2) function to test if two
strings hash into the same dynamic lock.


Meaning of the parameters is as follows:


- *key (var)* - key to be hashed in order to
obtain the index of a dynamic lock from the pool


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE, ONREPLY_ROUTE, 
BRANCH_ROUTE, LOCAL_ROUTE, STARTUP_ROUTE, TIMER_ROUTE|EVENT_ROUTE.


```opensips title="get_dynamic_lock usage"
...
# acquire and release a dynamic lock on the "Call-ID" header field value
if (!get_dynamic_lock($ci)) {
	xlog("Error while getting dynamic lock!\n");
}
...
if (!release_dynamic_lock($ci) {
	xlog("Error while releasing dynamic lock!\n");
}
...
```


#### release_dynamic_lock(key)


Release the dynamic lock corresponding to "key".  Nothing will happen
if the lock is not acquired.


Meaning of the parameters is as follows:


- *key (var)* - key to be hashed in order to
obtain the index of a dynamic lock from the pool


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE, ONREPLY_ROUTE, 
BRANCH_ROUTE, LOCAL_ROUTE, STARTUP_ROUTE, TIMER_ROUTE|EVENT_ROUTE.


```opensips title="release_dynamic_lock usage"
...
# acquire and release a dynamic lock on the "Call-ID" header field value
if (!get_dynamic_lock($ci)) {
	xlog("Error while getting dynamic lock!\n");
}
...
if (!release_dynamic_lock($ci) {
	xlog("Error while releasing dynamic lock!\n");
}
...
```


#### strings_share_lock(key1, key2)


A function used to test if two strings will generate the same hash value.
Its purpose is to prevent deadlocks resulted when a process successively
acquires two dynamic locks on two strings which happen to point to the same
lock.


Theoretically, the chance of two strings generating the same hash value 
decreases proportionally to the increase of the
[lock pool size](#lock_pool_size-integer) parameter. In
other words, the more dynamic locks you configure the module with, the higher
the chance that all individual protected regions of your script will run in
parallel, without waiting for each other.


Meaning of the parameters is as follows:


- *key1, key2 (string)* - strings which will have
their hash values compared


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE, ONREPLY_ROUTE, 
BRANCH_ROUTE, LOCAL_ROUTE, STARTUP_ROUTE, TIMER_ROUTE|EVENT_ROUTE.


```opensips title="strings_share_lock usage"
...
# Proper way of acquiring two dynamic locks successively
if (!get_dynamic_lock($avp(foo))) {
	xlog("Error while getting dynamic lock!\n");
}

if (!strings_share_lock($avp(foo), $avp(bar)) {
	if (!get_dynamic_lock($avp(bar))) {
		xlog("Error while getting dynamic lock!\n");
	}
}
...
if (!strings_share_lock($avp(foo), $avp(bar)) {
	if (!release_dynamic_lock($avp(bar)) {
		xlog("Error while releasing dynamic lock!\n");
	}
}

if (!release_dynamic_lock($avp(foo)) {
	xlog("Error while releasing dynamic lock!\n");
}
...
```


#### get_accurate_time(sec, usec, [str_sec_usec])


Fetch the current Unix time epoch with microsecond precision.
Optionally, print this value as a floating point number (3rd parameter).


Meaning of the parameters is as follows:


- *sec (int)* - the current Unix timestamp (integer part)
- *usec (int)* - the current Unix timestamp (decimal part)
- *str_sec_usec (string, optional)* - the current Unix
timestamp as a floating point number (6-digit precision)


This function can be used from REQUEST_ROUTE, FAILURE_ROUTE, ONREPLY_ROUTE,
BRANCH_ROUTE, LOCAL_ROUTE, STARTUP_ROUTE, TIMER_ROUTE, EVENT_ROUTE.


```opensips title="get_accurate_time usage"
...
get_accurate_time($var(sec), $var(usec));
xlog("Current Unix timestamp: $var(sec) s, $var(usec) us\n");
...
```


#### shuffle_avps(name)


Randomly shuffles AVPs with *name*.


Meaning of the parameters is as follows:


- *name (variable)* - name of AVP to shuffle.


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


```opensips title="shuffle_avps usage"
...
$avp(foo) := "str1";
$avp(foo)  = "str2";
$avp(foo)  = "str3";
xlog("Initial AVP list is: $(avp(foo)[*])\n");       # str3 str2 str1
if(shuffle_avps( $avp(foo) ))
    xlog("Shuffled AVP list is: $(avp(foo)[*])\n");  # str1, str3, str2 (for example)
...
				
```


### Exported Asynchronous Functions


#### sleep(seconds)


Waits a number of seconds. This function does exactly the same as
[sleep](#sleeptime),
but in an asynchronous way. The script execution is suspended until
the waiting is done; then OpenSIPS resumes the script execution via 
the resume route.


To read and understand more on the asynchronous functions, how to 
use them and what are their advantages, please refer to the OpenSIPS
online Manual.


```opensips title="async sleep usage"
{
...
async( sleep(5), after_sleep );
}

route[after_sleep] {
...
}
```


#### usleep(seconds)


Waits a number of micro-seconds. This function does exactly the same as
[usleep](#usleeptime),
but in an asynchronous way. The script execution is suspended until
the waiting is done; then OpenSIPS resumes the script execution via 
the resume route.


To read and understand more on the asynchronous functions, how to 
use them and what are their advantages, please refer to the OpenSIPS
online Manual.


```opensips title="async usleep usage"
{
...
async( usleep(1000), after_usleep );
}

route[after_usleep] {
...
}
```


### Exported MI Functions


#### cfgutils:rand_set_prob


Set the probability value to the given parameter.


Parameters:


- *prob_proc* - the parameter should be
a percent value (number from 0 to 99).


```bash title="cfgutils:rand_set_prob usage"
...
$ opensips-cli -x mi cfgutils:rand_set_prob 10
...
```


#### cfgutils:rand_reset_prob


Reset the probability value to the inital start value.


This command don't need a parameter.


```bash title="cfgutils:rand_reset_prob usage"
...
$ opensips-cli -x mi cfgutils:rand_reset_prob
...
```


#### cfgutils:rand_get_prob


Return the actual probability setting.


The function return the actual probability value.


```bash title="cfgutils:rand_get_prob usage"
...
$ opensips-cli -x mi cfgutils:rand_get_prob
The actual probability is 50 percent.
...
```


#### cfgutils: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.


```bash title="cfgutils:check_config_hash usage"
...
$ opensips-cli -x mi cfgutils:check_config_hash
The actual config file hash is identical to the stored one.
...
```


#### cfgutils: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.


```bash title="cfgutils:get_config_hash usage"
...
$ opensips-cli -x mi cfgutils:get_config_hash
1580a37104eb4de69ab9f31ce8d6e3e0
...
```


#### cfgutils: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


```bash title="cfgutils:shv_set usage"
...
$ opensips-cli -x mi cfgutils:shv_set debug int 0
...
```


#### cfgutils: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.


```bash title="cfgutils:shv_get usage"
...
$ opensips-cli -x mi cfgutils:shv_get debug
$ opensips-cli -x mi cfgutils:shv_get
...
```


### Exported Pseudo-Variables


#### $env(name)


This PV provides access to the environment variable 'name'.


```opensips title="env(name) pseudo-variable usage"
...
xlog("PATH environment variable is $env(PATH)\n");
...
				 
```


#### $RANDOM


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


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


#### $ctime(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)


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


#### $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.


```opensips title="shv(name) pseudo-variable usage"
...
modparam("cfgutils", "shvset", "debug=i:1")
...
if ($shv(debug) == 1) {
	xlog("request: $rm from $fu to $ru\n");
}
...
				 
```
<!-- CONTRIBUTORS -->

### License

All documentation files (i.e. .md extension) are licensed under the Creative Common License 4.0
