---
title: "cpl_c Module"
description: "cpl_c modules implements a CPL (Call Processing Language) interpreter. Support for uploading/downloading/removing scripts via SIP REGISTER method is present."
---

## Admin Guide


### Overview


cpl_c modules implements a CPL (Call Processing Language) 
		interpreter. Support for uploading/downloading/removing scripts via 
		SIP REGISTER method is present.


### Dependencies


#### OpenSIPS Modules


The following modules must be loaded before this module:


- *any DB module- a DB module for interfacing the DB 
				operations (modules like mysql, postgres, dbtext, etc)*
- *TM (Transaction) module- used for proxying/forking 
				requests*
- *SL (StateLess) module - used for sending stateless 
				reply when responding to REGISTER request or for sending back 
				error responses*
- *USRLOC (User Location) module - used for implementing
				lookup("registration") tag (adding into location set of the
				users' contact)*


#### External Libraries or Applications


The following libraries or applications must be installed 
				before running OpenSIPS with this module loaded:


- *libxml2 and libxml2-devel - on some SO, these to 
					packages are merged into libxml2. This library contains an 
					engine for XML parsing, DTD validation and
					DOM manipulation.*


### Exported Parameters


#### db_url (string)


A SQL URL have to be given to the module for knowing where the 
				database containing the table with CPL scripts is locates. If 
				required a user name and password can be specified for allowing 
				the module to connect to the database server.


*Default value is "mysql://opensips:opensipsrw@localhost/opensips".*


```c title="Set db_url parameter"
...
modparam("cpl_c","db_url","dbdriver://username:password@dbhost/dbname")
...
```


#### db_table (string)


Indicates the name of the table that store the CPL scripts. 
				This table must be locate into the database specified by 
				"db_url" parameter. For more about the format of the CPL
				table please see the modules/cpl_c/init.mysql file.


*Default value is "cpl".*


```c title="Set db_table parameter"
...
modparam("cpl_c","cpl_table","cpl")
...
```


#### username_column (string)


Indicates the name of the column used for storing the username.


*Default value is "username".*


```c title="Set username_column parameter"
...
modparam("cpl_c","username_column","username")
...
```


#### domain_column (string)


Indicates the name of the column used for storing the domain.


*Default value is "domain".*


```c title="Set domain_column parameter"
...
modparam("cpl_c","domain_column","domain")
...
```


#### cpl_xml_column (string)


Indicates the name of the column used for storing the 
				the XML version of the cpl script.


*Default value is "cpl_xml".*


```c title="Set cpl_xml_column parameter"
...
modparam("cpl_c","cpl_xml_column","cpl_xml")
...
```


#### cpl_bin_column (string)


Indicates the name of the column used for storing the 
				the binary version of the cpl script (compiled version).


*Default value is "cpl_bin".*


```c title="Set cpl_bin_column parameter"
...
modparam("cpl_c","cpl_bin_column","cpl_bin")
...
```


#### cpl_dtd_file (string)


Points to the DTD file describing the CPL grammar. The file 
				name may include also the path to the file. This path can be 
				absolute or relative (be careful the path will be relative 
				to the starting directory of OpenSIPS).


*This parameter is MANDATORY!*


```c title="Set cpl_dtd_file parameter"
...
modparam("cpl_c","cpl_dtd_file","/etc/opensips/cpl-06.dtd")
...
```


#### log_dir (string)


Points to a directory where should be created all the log file 
				generated by the LOG CPL node. A log file per user will be 
				created (on demand) having the name username.log.


*If this parameter is absent, the logging will be disabled 
					without generating error on execution.*


```c title="Set log_dir parameter"
...
modparam("cpl_c","log_dir","/var/log/opensips/cpl")
...
```


#### proxy_recurse (int)


Tells for how many time is allow to have recurse for PROXY CPL 
				node If it has value 2, when doing proxy, only twice the proxy 
				action will be re-triggered by  a redirect response; the third 
				time, the proxy execution will end by going on REDIRECTION 
				branch. The recurse feature can be disable by setting this 
				parameter to 0


*Default value of this parameter is 0.*


```c title="Set proxy_recurse parameter"
...
modparam("cpl_c","proxy_recurse",2)
...
```


#### proxy_route (string)


Before doing proxy (forward), a script route can be executed.
				All modifications made by that route will be reflected only for
				the current branch.


*Default value of this parameter is NULL (none).*


```c title="Set proxy_route parameter"
...
modparam("cpl_c","proxy_route", "1")
...
```


#### case_sensitive (int)


Tells if the username matching should be perform case 
				sensitive or not. Set it to a non zero value to force
				a case sensitive handling of usernames.


*Default value of this parameter is 0.*


```c title="Set case_sensitive parameter"
...
modparam("cpl_c","case_sensitive",1)
...
```


#### realm_prefix (string)


Defines a prefix for the domain part which should be ignored 
				in handling users and scripts.


*Default value of this parameter is empty string.*


```c title="Set realm_prefix parameter"
...
modparam("cpl_c","realm_prefix","sip.")
...
```


#### lookup_domain (string)


Used by lookup tag to indicate where to perform user location.
				Basically this is the name of the usrloc domain (table) where
				the user registrations are kept.


If set to empty string, the lookup node will be disabled - no
				user location will be performed.


*Default value of this parameter is NULL.*


```c title="Set lookup_domain parameter"
...
modparam("cpl_c","lookup_domain","location")
...
```


#### lookup_append_branches (int)


Tells if the lookup tag should append branches (to do parallel
				forking) if user_location lookup returns more than one contact.
				Set it to a non zero value to enable parallel forking for
				location lookup tag.


*Default value of this parameter is 0.*


```c title="Set lookup_append_branches parameter"
...
modparam("cpl_c","lookup_append_branches",1)
...
```


#### use_domain (integer)


Indicates if the domain part of the URI should be used in 
				user identification (otherwise only username part will be
				used).


*Default value is "0 (disabled)".*


```c title="Set use_domain parameter"
...
modparam("cpl_c","use_domain",1)
...
```


### Exported Functions


#### cpl_run_script(type,mode)


Starts the execution of the CPL script. The user name is 
				fetched from new_uri or requested uri or from To header -in 
				this order- (for incoming execution) or from FROM header (for 
				outgoing execution).
				Regarding the stateful/stateless message processing, the
				function  is very flexible, being able to run in different 
				modes (see below the"mode" parameter).
				Normally this function will end script execution.  There is no 
				guaranty that the CPL script interpretation ended when OpenSIPS 
				script ended also (for the same INVITE ;-)) - this can happen 
				when the CPL script does a PROXY and the script interpretation 
				pause after proxying and it will be resume when some reply is
				received (this can happen in a different process of OpenSIPS).


If the function returns true to script, if value "1" is 
				returned, the SIP server should continue with the normal 
				behavior as if no script existed; if value (2) is returned, it
				means no script was found, so nothing was done.


When some error is reported (a false return code), the 
				function itself haven't sent any SIP error reply (this can
				be done from script).


Meaning of the parameters is as follows:


- *type (string)* - which part of the script 
				should be run; set it to "incoming" for having the incoming 
				part of script executed (when an INVITE is received) or to 
				"outgoing" for running the outgoing part of script (when a 
				user is generating an INVITE - call).
- *mode (string)* - sets the interpreter mode as
				stateless/stateful behavior. The following modes are accepted:

  - *IS_STATELESS* - the current INVITE has 
					no transaction created yet. All replies (redirection or 
					deny) will be done is a stateless way. The execution will 
					switch to stateful only when proxy is done. So, if the 
					function returns, will be in stateless mode.
  - *IS_STATEFUL* - the current INVITE has 
					already a transaction associated. All signaling operations
					(replies or proxy) will be done in stateful way.So, if
					the function returns, will be in stateful mode.
  - *FORCE_STATEFUL* - the current INVITE 
					has no transaction created yet. All signaling operations
					will be done is a stateful way (on signaling, the
					transaction will be created from within the interpreter).
					So, if the function returns, will be in stateless mode.
*HINT*: is_stateful is very 
				difficult to manage from the routing script (script processing
				can continue in stateful mode); is_stateless is the fastest and
				less resources consumer (transaction is created only if
				proxying is done), but there is minimal protection against
				retransmissions (since replies are send stateless);
				force_stateful is a good compromise - all signaling is done
				stateful (retransmission protection) and in the same time, if
				returning to script, it will be in stateless mode (easy to
				continue the routing script execution)


This function can be used from REQUEST_ROUTE.


```c title="cpl_run_script usage"
...
cpl_run_script("incoming","force_stateful");
...
```


#### cpl_process_register()


This function MUST be called only for REGISTER requests. It 
				checks if the current REGISTER request is related or not with 
				CPL script upload/download/ remove. If it is, all the needed 
				operation will be done. For checking if the REGISTER is CPL 
				related, the function looks fist to "Content-Type" header. If 
				it exists and has a the mime type set to "application/cpl+xml" 
				means this is a CPL script upload/remove operation. The 
				distinction between to case is made by looking at 
				"Content-Disposition" header; id its value is 
				"script;action=store", means it's an upload; if it's 
				"script;action=remove", means it's a remove operation; other 
				values are considered to be errors. If no "Content-Type" 
				header is present, the function looks to "Accept" header and 
				if it contains the "*" or "application/cpl-xml" the request 
				it will be consider one for downloading CPL scripts.
				The functions returns to script only if the REGISTER is 
				not related to CPL. In other case, the function will send by 
				itself the necessary replies (stateless - using sl), including 
				for errors.


This function can be used from REQUEST_ROUTE.


```c title="cpl_process_register usage"
...
if ($rm=="REGISTER") {
    cpl_process_register();
}
...
```


#### cpl_process_register_norpl()


Same as "cpl_process_register" without 
				internally generating the reply. All information (script) is
				appended to the reply but without sending it out.


Main purpose of this function is to allow integration 
				between CPL and UserLocation services via same REGISTER
				messages.


This function can be used from REQUEST_ROUTE.


```c title="cpl_process_register_norpl usage"
...
if ($rm=="REGISTER") {
    cpl_process_register();
    # continue with usrloc part
    save("location");
}
...
```


### Exported MI Functions


#### LOAD_CPL


For the given user, loads the XML cpl file, compiles it into 
			binary format and stores both format into database.


Name: *LOAD_CPL*


Parameters:


- username : name of the user
- cpl_filename: file name


MI FIFO Command format:


```c
                 opensips-cli -x mi LOAD_CPL sip:bob@domain.com cpl_script.xml
```


#### REMOVE_CPL


For the given user, removes the entire database record 
			(XML cpl and binary cpl); user with empty cpl scripts are not 
			accepted.


Name: *REMOVE_CPL*


Parameters:


- username : name of the user


MI FIFO Command format:


```c
                 opensips-cli -x mi REMOVE_CPL sip:bob@domain.com
```


#### GET_CPL


For the given user, returns the CPL script in XML format.


Name: *GET_CPL*


Parameters:


- username : name of the user


MI FIFO Command format:


```c
                 opensips-cli -x mi GET_CPL sip:bob@domain.com
```


### Installation and Running


#### Database setup


Before running OpenSIPS with cpl_c, you have to setup the database 
			table where the module will store the CPL scripts. For that, if 
			the table was not created by the installation script or you choose
			to install everything by yourself you can use the cpc-create.sql
			SQL script in the database directories in the 
			opensips/scripts folder as template. 
			Database and table name can be set with module parameters so they 
			can be changed, but the name of the columns must be as they are 
			in the SQL script.
			You can also find the complete database documentation on the
			project webpage, [https://opensips.org/docs/db/db-schema-devel.html](https://opensips.org/docs/db/db-schema-devel.html).
<!-- CONTRIBUTORS -->

### License

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