B2B_ENTITIES

Anca-Maria Vamanu

   OpenSIPS

Edited by

Anca-Maria Vamanu

Edited by

Ovidiu Sas

   Copyright © 2009 Anca-Maria
   Vamanu
   Revision History
   Revision $Revision: 8103 $ $Date$
     __________________________________________________________

   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. server_hsize (int)
              1.3.2. client_hsize (int)
              1.3.3. script_req_route (str)
              1.3.4. script_reply_route (str)
              1.3.5. db_url (str)
              1.3.6. update_period (int)
              1.3.7. b2b_key_prefix (string)
              1.3.8. db_mode (int)
              1.3.9. db_table (str)
              1.3.10. replication_mode (int)

        1.4. Exported Functions

   2. Developer Guide

        2.1. b2b_load_api(b2b_api_t* api)
        2.2. server_new
        2.3. client_new
        2.4. send_request
        2.5. send_reply
        2.6. entity_delete
        2.7. restore_logic_info
        2.8. update_b2bl_param

   List of Examples

   1.1. Set server_hsize parameter
   1.2. Set client_hsize parameter
   1.3. Set script_req_route parameter
   1.4. Set script_repl_route parameter
   1.5. Set db_url parameter
   1.6. Set update_period parameter
   1.7. Set b2b_key_prefix parameter
   1.8. Set db_mode parameter
   1.9. Set db_table parameter
   1.10. Set replication_mode parameter
   2.1. b2b_api_t structure

Chapter 1. Admin Guide

1.1. Overview

   The B2BUA implementation in OpenSIPS is separated in two
   layers:
     * a lower one(coded in this module)- which implements the
       basic functions of a UAS and UAC
     * a upper one - which represents the logic engine of B2BUA,
       responsible of actually implementing the B2BUA services
       using the functions offered by the low level.

   This module stores records corresponding to the dialogs in
   which the B2BUA is involved. It exports an API to be called
   from other modules which offers functions for creating a new
   dialog record, for sending requests or replies in one dialog
   and will also notify the upper level module when a request or
   reply is received inside one stored dialog. The records are
   separated in two types: b2b server entities and b2b client
   entities depending on the mode they are created. An entity
   created for a received initial message will be a server entity,
   while a entity that will send an initial request(create a new
   dialog) will be a b2b client entity. The name corresponds to
   the behavior in the first transaction - if UAS - server entity
   and if UAC - client entity. This module does not implement a
   B2BUA alone, but needs a B2B logic implementing module.

   The module is able to respond to authentication challanges if
   the uac_auth module is loaded first. The list of credentials
   for b2b authentication is also provided by the uac_auth module.

1.2. Dependencies

1.2.1. OpenSIPS Modules

     * tm
     * a db module
     * uac_auth (mandatory if authentication is required)

1.2.2. External Libraries or Applications

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

1.3. Exported Parameters

1.3.1. server_hsize (int)

   The size of the hash table that stores the b2b server entities.
   It is the 2 logarithmic value of the real size.

   Default value is “9” (512 records).

   Example 1.1. Set server_hsize parameter
...
modparam("b2b_entities", "server_hsize", 10)
...

1.3.2. client_hsize (int)

   The size of the hash table that stores the b2b client entities.
   It is the 2 logarithmic value of the real size.

   Default value is “9” (512 records).

   Example 1.2. Set client_hsize parameter
...
modparam("b2b_entities", "client_hsize", 10)
...

1.3.3. script_req_route (str)

   The name of the b2b script route that will be called when B2B
   requests are received.

   Example 1.3. Set script_req_route parameter
...
modparam("b2b_entities", "script_req_route", "b2b_request")
...

1.3.4. script_reply_route (str)

   The name of the b2b script route that will be called when B2B
   replies are received.

   Example 1.4. Set script_repl_route parameter
...
modparam("b2b_entities", "script_reply_route", "b2b_reply")
...

1.3.5. db_url (str)

   Database URL. It is not compulsory, if not set data is not
   stored in database.

   Example 1.5. Set db_url parameter
...
modparam("b2b_entities", "db_url", "mysql://opensips:opensipsrw@127.0.0.
1/opensips")
...

1.3.6. update_period (int)

   The time interval at which to update the info in database.

   Default value is “100”.

   Example 1.6. Set update_period parameter
...
modparam("b2b_entities", "update_period", 60)
...

1.3.7. b2b_key_prefix (string)

   The string to use when generating the key ( it is inserted in
   the SIP messages as callid or to tag. It is useful to set this
   prefix if you use more instances of opensips B2BUA cascaded in
   the same architecture. Sometimes opensips B2BUA looks at the
   callid or totag to see if it has the format it uses to
   determine if the request was sent by it.

   Default value is “B2B”.

   Example 1.7. Set b2b_key_prefix parameter
...
modparam("b2b_entities", "b2b_key_prefix", "B2B1")
...

1.3.8. db_mode (int)

   The B2B modules have support for the 3 type of database storage

     * NO DB STORAGE - set this parameter to 0
     * WRITE THROUGH (synchronous write in database) - set this
       parameter to 1
     * WRITE BACK (update in db from time to time) - set this
       parameter to 2

   Default value is “2” (WRITE BACK).

   Example 1.8. Set db_mode parameter
...
modparam("b2b_entities", "db_mode", 1)
...

1.3.9. db_table (str)

   The name of the table that will be used for storing B2B
   entities

   Default value is “b2b_entities”

   Example 1.9. Set db_table parameter
...
modparam("b2b_entities", "db_table", "some table name")
...

1.3.10. replication_mode (int)

   Controls if the callid should be the same in more instances
   running at the same time. 0 will lead to generating of
   different callid's per instance 1 will lead to generating of
   the same callid's in more instances

   Default value is “0”

   Example 1.10. Set replication_mode parameter
...
modparam("b2b_entities", "replication_mode", 1)
...

1.4. Exported Functions

   The module does not export functions to be used in
   configuration script.

Chapter 2. Developer Guide

   The module provides an API that can be used from other OpenSIPS
   modules. The API offers the functions for creating and handing
   dialogs. A dialog can be created on a receipt initial message,
   and this will correspond to a b2b server entity, or initiated
   by the server and in this case a client entity will be created
   in b2b_entities module.

2.1.  b2b_load_api(b2b_api_t* api)

   This function binds the b2b_entities modules and fills the
   structure the exported functions that will be described in
   detail.

   Example 2.1. b2b_api_t structure
...
typedef struct b2b_api {
        b2b_server_new_t          server_new;
        b2b_client_new_t          client_new;

        b2b_send_request_t        send_request;
        b2b_send_reply_t          send_reply;

        b2b_entity_delete_t       entity_delete;

        b2b_restore_linfo_t       restore_logic_info;
        b2b_update_b2bl_param_t   update_b2bl_param;
}b2b_api_t;
...

2.2.  server_new

   Field type:
...
typedef str* (*b2b_server_new_t) (struct sip_msg* ,b2b_notify_t , void*
param);
...

   This function asks the b2b_entities modules to create a new
   server entity record. The internal processing actually extracts
   the dialog information from the message and constructs a record
   that will be stored in a hash table. The second parameters is a
   pointer to a function that the b2b_entities module will call
   when a event will come for that dialog (a request or reply).
   The third parameter is a pointer to a value that will be stored
   and given as a parameter when the notify function will be
   called(it has to be allocated in shared memory).

   The return value is an identifier for the record that will be
   mentioned when calling other functions that represent actions
   in the dialog(send request, send reply).

   The notify function has the following prototype:
...
typedef int (*b2b_notify_t)(struct sip_msg* msg, str* id, int type, void
* param);
...

   This function is called when a request or reply is received for
   a dialog handled by b2b_entities. The first parameter is the
   message, the second is the identifier for the dialog, the third
   is a flag that says which is the type of the message(it has two
   possible values - B2B_REQUEST and B2B_REPLY). The last
   parameter is the parameter by the upper module when the entity
   was created.

2.3.  client_new

   Field type:
...
typedef str* (*b2b_client_new_t) (client_info_t* , b2b_notify_t b2b_cbac
k,
                b2b_add_dlginfo_t add_dlginfo_f, str* param);
...

   This function asks the b2b_entities modules to create a new
   client entity record and also create a new dialog by sending an
   initial message. The parameters are all the values needed for
   the initial request to which the notify function and parameter
   are added. The b2b_cback parameter is a pointer to the callback
   that must be called when an event happens(receiving a reply or
   request) in the dialog created with this function. The
   add_dlginfo_f parameter is also a function pointer to a
   callback that will be called when a final success response will
   be received for the created dialog. The callback will receive
   as parameter the complete dialog information for the record. It
   should be stored and used when calling send_request or
   send_reply functions.

   The return value is an identifier for the record that will be
   mentioned when calling other functions that represent actions
   in the dialog(send request, send reply).

2.4.  send_request

   Field type:
...
typedef int (*b2b_send_request_t)(enum b2b_entity_type ,str* b2b_key, st
r* method,
                str* extra_headers, str* body, b2b_dlginfo_t*);
...

   This function asks the b2b_entities modules to send a request
   inside a b2b dialog identified by b2b_key. The first parameter
   is the entity type and can have two values: B2B_SERVER and
   B2B_CLIENT. The second is the identifier returned by the create
   function(server_new or client_new) and the next are the
   informations needed for the new request: method, extra_headers,
   body. The last parameter contains the dialog information -
   callid, to tag, from tag. These are needed to make a perfect
   match to of b2b_entities record for which a new request must be
   sent.

   The return value is 0 for success and a negative value for
   error.

2.5.  send_reply

   Field type:
...
typedef int (*b2b_send_reply_t)(enum b2b_entity_type et, str* b2b_key, i
nt code, str* text,
                str* body, str* extra_headers, b2b_dlginfo_t* dlginfo);
...

   This function asks the b2b_entities modules to send a reply
   inside a b2b dialog identified by b2b_key. The first parameter
   is the entity type and can have two values: B2B_SERVER and
   B2B_CLIENT. The second is the identifier returned by the create
   function(server_new or client_new) and the next are the
   informations needed for the new reply: code, text, body,
   extra_headers. The last parameter contains the dialog
   information used for matching the right record.

   The return value is 0 for success and a negative value for
   error.

2.6.  entity_delete

   Field type:
...
typedef void (*b2b_entity_delete_t)(enum b2b_entity_type et, str* b2b_ke
y,
         b2b_dlginfo_t* dlginfo);
...

   This function must be called by the upper level function to
   delete the records in b2b_entities. The records are not cleaned
   up by the b2b_entities module and the upper level module must
   take care to delete them.

2.7.  restore_logic_info

   Field type:
...
typedef int (*b2b_restore_linfo_t)(enum b2b_entity_type type, str* key,
                b2b_notify_t cback);
...

   This function is used at startup when loading the data from the
   database to restore the pointer to the callback function.

2.8.  update_b2bl_param

   Field type:
...
typedef int (*b2b_update_b2bl_param_t)(enum b2b_entity_type type, str* k
ey,
                str* param);
...

   This function can be used to change the logic param stored for
   an entity ( useful in case an entity is moved between logic
   records).
