cpl-c Module

Bogdan-Andrei Iancu

Edited by

Bogdan-Andrei Iancu

Revision History
Revision $Revision: 8740 $$Date$

Table of Contents

1. Admin Guide
1.1. Overview
1.2. Dependencies
1.2.1. OpenSIPS Modules
1.2.2. External Libraries or Applications
1.3. Exported Parameters
1.3.1. db_url (string)
1.3.2. db_table (string)
1.3.3. username_column (string)
1.3.4. domain_column (string)
1.3.5. cpl_xml_column (string)
1.3.6. cpl_bin_column (string)
1.3.7. cpl_dtd_file (string)
1.3.8. log_dir (string)
1.3.9. proxy_recurse (int)
1.3.10. proxy_route (string)
1.3.11. case_sensitive (int)
1.3.12. realm_prefix (string)
1.3.13. lookup_domain (string)
1.3.14. lookup_append_branches (int)
1.3.15. use_domain (integer)
1.4. Exported Functions
1.4.1. cpl_run_script(type,mode)
1.4.2. cpl_process_register()
1.4.3. cpl_process_register_norpl()
1.5. Exported MI Functions
1.5.1. LOAD_CPL
1.5.3. GET_CPL
1.6. Installation and Running
1.6.1. Database setup

List of Examples

1.1. Set db_url parameter
1.2. Set db_table parameter
1.3. Set username_column parameter
1.4. Set domain_column parameter
1.5. Set cpl_xml_column parameter
1.6. Set cpl_bin_column parameter
1.7. Set cpl_dtd_file parameter
1.8. Set log_dir parameter
1.9. Set proxy_recurse parameter
1.10. Set proxy_route parameter
1.11. Set case_sensitive parameter
1.12. Set realm_prefix parameter
1.13. Set lookup_domain parameter
1.14. Set lookup_append_branches parameter
1.15. Set use_domain parameter
1.16. cpl_run_script usage
1.17. cpl_process_register usage
1.18. cpl_process_register_norpl usage

Chapter 1. Admin Guide

1.1. Overview

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

1.2. Dependencies

1.2.1. 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)

1.2.2. 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.

1.3. Exported Parameters

1.3.1. 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.

Example 1.1. Set db_url parameter


1.3.2. 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.

Example 1.2. Set db_table parameter


1.3.3. username_column (string)

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

Default value is username.

Example 1.3. Set username_column parameter


1.3.4. domain_column (string)

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

Default value is domain.

Example 1.4. Set domain_column parameter


1.3.5. 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.

Example 1.5. Set cpl_xml_column parameter


1.3.6. 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.

Example 1.6. Set cpl_bin_column parameter


1.3.7. 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!

Example 1.7. Set cpl_dtd_file parameter


1.3.8. 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.

Example 1.8. Set log_dir parameter


1.3.9. 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.

Example 1.9. Set proxy_recurse parameter


1.3.10. 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).

Example 1.10. Set proxy_route parameter

modparam("cpl-c","proxy_route", "1")

1.3.11. 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.

Example 1.11. Set case_sensitive parameter


1.3.12. 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.

Example 1.12. Set realm_prefix parameter


1.3.13. 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.

Example 1.13. Set lookup_domain parameter


1.3.14. 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.

Example 1.14. Set lookup_append_branches parameter


1.3.15. 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).

Example 1.15. Set use_domain parameter


1.4. Exported Functions

1.4.1.  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 - 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 - 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.

Example 1.16. cpl_run_script usage


1.4.2.  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.

Example 1.17. cpl_process_register usage

if (method=="REGISTER") {

1.4.3.  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.

Example 1.18. cpl_process_register_norpl usage

if (method=="REGISTER") {
    # continue with usrloc part

1.5. Exported MI Functions

1.5.1.  LOAD_CPL

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



  • username : name of the user

  • cpl_filename: file name

MI FIFO Command format:


1.5.2.  REMOVE_CPL

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



  • username : name of the user

MI FIFO Command format:


1.5.3.  GET_CPL

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



  • username : name of the user

MI FIFO Command format:


1.6. Installation and Running

1.6.1. 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, http://www.opensips.org/html/docs/db/db-schema-devel.html.