dialog Module

Bogdan-Andrei Iancu

   Voice Sistem SRL

Edited by

Bogdan-Andrei Iancu

   Copyright © 2006 voice-system.ro
   Revision History
   Revision $Revision: 5731 $ $Date: 2008-08-06 12:08:33 +0200
                              (Mi, 06 Aug 2008) $
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. How it works
        1.3. Dialog profiling
        1.4. Dependencies

              1.4.1. Kamailio Modules
              1.4.2. External Libraries or Applications

        1.5. Exported Parameters

              1.5.1. enable_stats (integer)
              1.5.2. hash_size (integer)
              1.5.3. rr_param (string)
              1.5.4. dlg_flag (integer)
              1.5.5. timeout_avp (string)
              1.5.6. default_timeout (integer)
              1.5.7. dlg_extra_hdrs (string)
              1.5.8. dlg_match_mode (integer)
              1.5.9. db_url (string)
              1.5.10. db_mode (integer)
              1.5.11. db_update_period (integer)
              1.5.12. db_fetch_rows (integer)
              1.5.13. table_name (string)
              1.5.14. callid_column (string)
              1.5.15. from_uri_column (string)
              1.5.16. from_tag_column (string)
              1.5.17. to_uri_column (string)
              1.5.18. to_tag_column (string)
              1.5.19. caller_cseq_column (string)
              1.5.20. callee_cseq_column (string)
              1.5.21. caller_route_column (string)
              1.5.22. callee_route_column (string)
              1.5.23. caller_contact_column (string)
              1.5.24. callee_contact_column (string)
              1.5.25. caller_sock_column (string)
              1.5.26. callee_sock_column (string)
              1.5.27. h_id_column (string)
              1.5.28. h_entry_column (string)
              1.5.29. state_column (string)
              1.5.30. start_time_column (string)
              1.5.31. timeout_column (string)
              1.5.32. sflags_column (string)
              1.5.33. toroute_column (string)
              1.5.34. profiles_with_value (string)
              1.5.35. profiles_no_value (string)
              1.5.36. bridge_controller (string)

        1.6. Exported Functions

              1.6.1. set_dlg_profile(profile,[value])
              1.6.2. unset_dlg_profile(profile,[value])
              1.6.3. is_in_profile(profile,[value])
              1.6.4. get_profile_size(profile,[value],size)
              1.6.5. dlg_isflagset(flag)
              1.6.6. dlg_setflag(flag)
              1.6.7. dlg_resetflag(flag)
              1.6.8. dlg_bye(side)
              1.6.9. dlg_refer(side, address)
              1.6.10. dlg_manage()
              1.6.11. dlg_bridge(from, to, op)
              1.6.12. dlg_get(callid, ftag, ttag)

        1.7. Exported statistics

              1.7.1. active_dialogs
              1.7.2. early_dialogs
              1.7.3. processed_dialogs
              1.7.4. expired_dialogs
              1.7.5. failed_dialogs

        1.8. Exported MI Functions

              1.8.1. dlg_list
              1.8.2. dlg_list_ctx
              1.8.3. dlg_end_dlg
              1.8.4. profile_get_size
              1.8.5. profile_list_dlgs
              1.8.6. dlg_bridge

        1.9. Exported pseudo-variables

              1.9.1. $DLG_count
              1.9.2. $DLG_status
              1.9.3. $DLG_lifetime
              1.9.4. $dlg(...)
              1.9.5. $dlg_ctx(...)

   2. Developer Guide

        2.1. Available Functions

              2.1.1. register_dlgcb (dialog, type, cb, param,
                      free_param_cb)

   3. Frequently Asked Questions

   List of Examples

   1.1. Set enable_stats parameter
   1.2. Set hash_size parameter
   1.3. Set rr_param parameter
   1.4. Set dlg_flag parameter
   1.5. Set timeout_avp parameter
   1.6. Set default_timeout parameter
   1.7. Set dlf_extra_hdrs parameter
   1.8. Set dlg_match_mode parameter
   1.9. Set db_url parameter
   1.10. Set db_mode parameter
   1.11. Set db_update_period parameter
   1.12. Set db_fetch_rows parameter
   1.13. Set table_name parameter
   1.14. Set callid_column parameter
   1.15. Set from_uri_column parameter
   1.16. Set from_tag_column parameter
   1.17. Set to_uri_column parameter
   1.18. Set to_tag_column parameter
   1.19. Set caller_cseq_column parameter
   1.20. Set callee_cseq_column parameter
   1.21. Set caller_route_column parameter
   1.22. Set to_route_column parameter
   1.23. Set caller_contact_column parameter
   1.24. Set callee_contact_column parameter
   1.25. Set caller_sock_column parameter
   1.26. Set callee_sock_column parameter
   1.27. Set h_id_column parameter
   1.28. Set h_entry_column parameter
   1.29. Set state_column parameter
   1.30. Set start_time_column parameter
   1.31. Set timeout_column parameter
   1.32. Set sflags_column parameter
   1.33. Set toroute_column parameter
   1.34. Set profiles_with_value parameter
   1.35. Set profiles_no_value parameter
   1.36. Set bridge_controller parameter
   1.37. set_dlg_profile usage
   1.38. unset_dlg_profile usage
   1.39. is_in_profile usage
   1.40. get_profile_size usage
   1.41. dlg_isflagset usage
   1.42. dlg_setflag usage
   1.43. dlg_resetflag usage
   1.44. dlg_bye usage
   1.45. dlg_refer usage
   1.46. dlg_manage usage
   1.47. dlg_bridge usage
   1.48. dlg_get usage

Chapter 1. Admin Guide

1.1. Overview

   The dialog module provides dialog awareness to the Kamailio
   proxy. Its functionality is to keep trace of the current
   dialogs, to offer information about them (like how many dialogs
   are active). The module exports several functions that could be
   used directly from scripts.

   The module, via an internal API, also provide the foundation to
   build on top of it more complex dialog-based functionalities
   via other Kamailio modules.

1.2. How it works

   To create the dialog associated to an initial request, the flag
   "dlg_flag" (Section 1.5.4, "dlg_flag (integer)") must be set
   before creating the corresponding transaction.

   The dialog is automatically destroyed when a "BYE" is received.
   In case of no "BYE", the dialog lifetime is controlled via the
   default timeout (see "default_timeout" - Section 1.5.6,
   "default_timeout (integer)") and custom timeout (see
   "timeout_avp" - Section 1.5.5, "timeout_avp (string)"). The
   dialog timeout is reset each time a sequential request passes.

1.3. Dialog profiling

   Dialog profiling is a mechanism that helps in classifying,
   sorting and keeping trace of certain types of dialogs, using
   whatever properties of the dialog (like caller, destination,
   type of calls, etc). Dialogs can be dynamically added in
   different (and several) profile tables - logically, each
   profile table can have a special meaning (like dialogs outside
   the domain, dialogs terminated to PSTN, etc).

   There are two types of profiles:
     * with no value - a dialog simply belongs to a profile. (like
       outbound calls profile). There is no other additional
       information to describe the dialog's belonging to the
       profile;
     * with value - a dialog belongs to a profile having a certain
       value (like in caller profile, where the value is the
       caller ID). The belonging of the dialog to the profile is
       strictly related to the value.

   A dialog can be added to multiple profiles in the same time.

   Profiles are visible (at the moment) in the request route (for
   initial and sequential requests) and in the branch, failure and
   reply routes of the original request.

1.4. Dependencies

1.4.1. Kamailio Modules

   The following modules must be loaded before this module:
     * TM - Transaction module
     * RR - Record-Route module

1.4.2. External Libraries or Applications

   The following libraries or applications must be installed
   before running Kamailio with this module loaded:
     * None.

1.5. Exported Parameters

1.5.1. enable_stats (integer)

   If the statistics support should be enabled or not. Via
   statistic variables, the module provide information about the
   dialog processing. Set it to zero to disable or to non-zero to
   enable it.

   Default value is "1 (enabled)".

   Example 1.1. Set enable_stats parameter
...
modparam("dialog", "enable_stats", 0)
...

1.5.2. hash_size (integer)

   The size of the hash table internally used to keep the dialogs.
   A larger table is much faster but consumes more memory. The
   hash size must be a power of 2 number.

   IMPORTANT: If dialogs' information should be stored in a
   database, a constant hash_size should be used, otherwise the
   restored process will not take place. If you really want to
   modify the hash_size you must delete all table's rows before
   restarting openser.

   Default value is "4096".

   Example 1.2. Set hash_size parameter
...
modparam("dialog", "hash_size", 1024)
...

1.5.3. rr_param (string)

   Name of the Record-Route parameter to be added with the dialog
   cookie. It is used for fast dialog matching of the sequential
   requests.

   Default value is "did".

   Example 1.3. Set rr_param parameter
...
modparam("dialog", "rr_param", "xyz")
...

1.5.4. dlg_flag (integer)

   Flag to be used for marking if a dialog should be constructed
   for the current request (make sense only for initial requests).

   Default value is "none".

   Example 1.4. Set dlg_flag parameter
...
modparam("dialog", "dlg_flag", 4)
...

1.5.5. timeout_avp (string)

   The specification of an AVP to contain a custom timeout (in
   seconds) for the dialog. It may be used only in a request
   (initial or sequential) context

   Default value is "none".

   Example 1.5. Set timeout_avp parameter
...
modparam("dialog", "timeout_avp", "$avp(i:10)")
...

1.5.6. default_timeout (integer)

   The default dialog timeout (in seconds) if no custom one is
   set.

   Default value is "43200 (12 hours)".

   Example 1.6. Set default_timeout parameter
...
modparam("dialog", "default_timeout", 21600)
...

1.5.7. dlg_extra_hdrs (string)

   A string containing the extra headers (full format, with EOH)
   to be added in the requests generated by the module (like
   BYEs).

   Default value is "NULL".

   Example 1.7. Set dlf_extra_hdrs parameter
...
modparam("dialog", "dlg_extra_hdrs", "Hint: credit expired\r\n")
...

1.5.8. dlg_match_mode (integer)

   How the seqential requests should be matched against the known
   dialogs. The modes are a combination between matching based on
   a cookie (DID) stored as cookie in Record-Route header and the
   matching based on SIP elements (as in RFC3261).

   The supported modes are:
     * 0 - DID_ONLY - the match is done exclusively based on DID;
     * 1 - DID_FALLBACK - the match is first tried based on DID
       and if not present, it will fallback to SIP matching;
     * 2 - DID_NONE - the match is done exclusively based on SIP
       elements; no DID information is added in RR.

   Default value is "0 (DID_ONLY)".

   Example 1.8. Set dlg_match_mode parameter
...
modparam("dialog", "dlg_match_mode", 1)
...

1.5.9. db_url (string)

   If you want to store the information about the dialogs in a
   database a database url must be specified.

   Default value is "mysql://openser:openserrw@localhost/openser".

   Example 1.9. Set db_url parameter
...
modparam("dialog", "db_url", "dbdriver://username:password@dbhost/dbname
")
...

1.5.10. db_mode (integer)

   Describe how to push into the DB the dialogs' information from
   memory.

   The supported modes are:
     * 0 - NO_DB - the memory content is not flushed into DB;
     * 1 - REALTIME - any dialog information changes will be
       reflected into the database immediatly.
     * 2 - DELAYED - the dialog information changes will be
       flushed into DB periodically, based on a timer routine.
     * 3 - SHUTDOWN - the dialog information will be flushed into
       DB only at shutdown - no runtime updates.

   Default value is "0".

   Example 1.10. Set db_mode parameter
...
modparam("dialog", "db_mode", 1)
...

1.5.11. db_update_period (integer)

   The interval (seconds) at which to update dialogs' information
   if you chose to store the dialogs' info at a given interval. A
   too short interval will generate intensiv database operations,
   a too large one will not notice short dialogs.

   Default value is "60".

   Example 1.11. Set db_update_period parameter
...
modparam("dialog", "db_update_period", 120)
...

1.5.12. db_fetch_rows (integer)

   The number of the rows to be fetched at once from database when
   loading the dialog records at startup from the database. This
   value can be used to tune the load time at startup. For 1MB of
   private memory (default) it should be below 400. The database
   driver must support fetch_result() capability. A value of 0
   means the functionality is disabled.

   Default value is "200".

   Example 1.12. Set db_fetch_rows parameter
...
modparam("dialog", "db_fetch_rows", 500)
...

1.5.13. table_name (string)

   If you want to store the information about the dialogs in a
   database a table name must be specified.

   Default value is "dialog".

   Example 1.13. Set table_name parameter
...
modparam("dialog", "table_name", "my_dialog")
...

1.5.14. callid_column (string)

   The column's name in the database to store the dialogs' callid.

   Default value is "callid".

   Example 1.14. Set callid_column parameter
...
modparam("dialog", "callid_column", "callid_c_name")
...

1.5.15. from_uri_column (string)

   The column's name in the database to store the caller's sip
   address.

   Default value is "from_uri".

   Example 1.15. Set from_uri_column parameter
...
modparam("dialog", "from_uri_column", "from_uri_c_name")
...

1.5.16. from_tag_column (string)

   The column's name in the database to store the From tag from
   the Invite request.

   Default value is "from_tag".

   Example 1.16. Set from_tag_column parameter
...
modparam("dialog", "from_tag_column", "from_tag_c_name")
...

1.5.17. to_uri_column (string)

   The column's name in the database to store the calee's sip
   address.

   Default value is "to_uri".

   Example 1.17. Set to_uri_column parameter
...
modparam("dialog", "to_uri_column", "to_uri_c_name")
...

1.5.18. to_tag_column (string)

   The column's name in the database to store the To tag from the
   200 OK response to the Invite request, if present.

   Default value is "to_tag".

   Example 1.18. Set to_tag_column parameter
...
modparam("dialog", "to_tag_column", "to_tag_c_name")
...

1.5.19. caller_cseq_column (string)

   The column's name in the database to store the cseq from caller
   side.

   Default value is "caller_cseq".

   Example 1.19. Set caller_cseq_column parameter
...
modparam("dialog", "caller_cseq_column", "column_name")
...

1.5.20. callee_cseq_column (string)

   The column's name in the database to store the cseq from callee
   side.

   Default value is "callee_cseq".

   Example 1.20. Set callee_cseq_column parameter
...
modparam("dialog", "callee_cseq_column", "column_name")
...

1.5.21. caller_route_column (string)

   The column's name in the database to store the route records
   from caller side (proxy to caller).

   Default value is "caller_route_set".

   Example 1.21. Set caller_route_column parameter
...
modparam("dialog", "caller_route_column", "column_name")
...

1.5.22. callee_route_column (string)

   The column's name in the database to store the route records
   from callee side (proxy to callee).

   Default value is "callee_route_set".

   Example 1.22. Set to_route_column parameter
...
modparam("dialog", "to_route_column", "column_name")
...

1.5.23. caller_contact_column (string)

   The column's name in the database to store the caller's contact
   uri.

   Default value is "from_contact".

   Example 1.23. Set caller_contact_column parameter
...
modparam("dialog", "caller_contact_column", "column_name")
...

1.5.24. callee_contact_column (string)

   The column's name in the database to store the callee's contact
   uri.

   Default value is "callee_contact".

   Example 1.24. Set callee_contact_column parameter
...
modparam("dialog", "callee_contact_column", "column_name")
...

1.5.25. caller_sock_column (string)

   The column's name in the database to store the information
   about the local interface receiving the traffic from caller.

   Default value is "caller_sock".

   Example 1.25. Set caller_sock_column parameter
...
modparam("dialog", "caller_sock_column", "column_name")
...

1.5.26. callee_sock_column (string)

   The column's name in the database to store information about
   the local interface receiving the traffic from callee.

   Default value is "callee_contact".

   Example 1.26. Set callee_sock_column parameter
...
modparam("dialog", "callee_sock_column", "column_name")
...

1.5.27. h_id_column (string)

   The column's name in the database to store the dialogs' hash id
   information.

   Default value is "hash_id".

   Example 1.27. Set h_id_column parameter
...
modparam("dialog", "h_id_column", "hash_id_c_name")
...

1.5.28. h_entry_column (string)

   The column's name in the database to store the dialogs' hash
   entry information.

   Default value is "hash_entry".

   Example 1.28. Set h_entry_column parameter
...
modparam("dialog", "h_entry_column", "h_entry_c_name")
...

1.5.29. state_column (string)

   The column's name in the database to store the dialogs' state
   information.

   Default value is "state".

   Example 1.29. Set state_column parameter
...
modparam("dialog", "state_column", "state_c_name")
...

1.5.30. start_time_column (string)

   The column's name in the database to store the dialogs' start
   time information.

   Default value is "start_time".

   Example 1.30. Set start_time_column parameter
...
modparam("dialog", "start_time_column", "start_time_c_name")
...

1.5.31. timeout_column (string)

   The column's name in the database to store the dialogs'
   timeout.

   Default value is "timeout".

   Example 1.31. Set timeout_column parameter
...
modparam("dialog", "timeout_column", "timeout_c_name")
...

1.5.32. sflags_column (string)

   The column's name in the database to store the script flags.

   Default value is "sflags".

   Example 1.32. Set sflags_column parameter
...
modparam("dialog", "sflags_column", "s_flags")
...

1.5.33. toroute_column (string)

   The column's name in the database to store the index of the
   route to be executed at timeout.

   Default value is "toroute".

   Example 1.33. Set toroute_column parameter
...
modparam("dialog", "toroute_column", "timeout_route")
...

1.5.34. profiles_with_value (string)

   List of names for profiles with values.

   Default value is "empty".

   Example 1.34. Set profiles_with_value parameter
...
modparam("dialog", "profiles_with_value", "caller ; my_profile")
...

1.5.35. profiles_no_value (string)

   List of names for profiles without values.

   Default value is "empty".

   Example 1.35. Set profiles_no_value parameter
...
modparam("dialog", "profiles_no_value", "inbound ; outbound")
...

1.5.36. bridge_controller (string)

   SIP address to be used in From header when initiating a call
   bridge.

   Default value is "sip:controller@kamailio.org".

   Example 1.36. Set bridge_controller parameter
...
modparam("dialog", "bridge_controller", "sip:ctd@kamailio.org")
...

1.6. Exported Functions

1.6.1.  set_dlg_profile(profile,[value])

   Inserts the current dialog into a profile. Note that the
   profile does not supports values, this will be silently
   discarded. Also, there is no check for inserting the same
   dialog in the same profile for multiple times.

   Meaning of the parameters is as follows:
     * profile - name of the profile to be added to;
     * value (optional) - string value to define the belonging of
       the dialog to the profile - note that the profile must
       support values. Pseudo-variables are supported.

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

   Example 1.37. set_dlg_profile usage
...
set_dlg_profile("inbound_call");
set_dlg_profile("caller","$fu");
...

1.6.2.  unset_dlg_profile(profile,[value])

   Removes the current dialog from a profile.

   Meaning of the parameters is as follows:
     * profile - name of the profile to be removed from;
     * value (optional) - string value to define the belonging of
       the dialog to the profile - note that the profile must
       support values. Pseudo-variables are supported.

   This function can be used from BRANCH_ROUTE, REPLY_ROUTE and
   FAILURE_ROUTE.

   Example 1.38. unset_dlg_profile usage
...
unset_dlg_profile("inbound_call");
unset_dlg_profile("caller","$fu");
...

1.6.3.  is_in_profile(profile,[value])

   Checks if the current dialog belongs to a profile. If the
   profile supports values, the check can be reinforced to take
   into account a specific value - if the dialog was inserted into
   the profile for a specific value. If no value is passed, only
   simply belonging of the dialog to the profile is checked. Note
   that if the profile does not supports values, this will be
   silently discarded.

   Meaning of the parameters is as follows:
     * profile - name of the profile to be checked against;
     * value (optional) - string value to further restrict the
       check. Pseudo-variables are supported.

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

   Example 1.39. is_in_profile usage
...
if (is_in_profile("inbound_call")) {
        log("this request belongs to a inbound call\n");
}
...
if (is_in_profile("caller","XX")) {
        log("this request belongs to a call of user XX\n");
}
...

1.6.4.  get_profile_size(profile,[value],size)

   Returns the number of dialogs belonging to a profile. If the
   profile supports values, the check can be reinforced to take
   into account a specific value - how many dialogs were inserted
   into the profile with a specific value. If no value is passed,
   only simply belonging of the dialog to the profile is checked.
   Note that if the profile does not supports values, this will be
   silently discarded.

   Meaning of the parameters is as follows:
     * profile - name of the profile to get the size for;
     * value (optional) - string value to further restrict the
       check. Pseudo-variables are supported;
     * size - an AVP or script variable to return the profile size
       in.

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

   Example 1.40. get_profile_size usage
...
get_profile_size("inbound_call","$avp(size)");
xlog("currently there are $avp(size) inbound calls\n");
...
get_profile_size("caller","$fu");
xlog("currently, the user %fu has $avp(size) active outgoing calls\n");
...

1.6.5.  dlg_isflagset(flag)

   Check if the dialog flag is set or not.

   Meaning of the parameters is as follows:
     * flag - index of the flag - can be pseudo-variable.

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

   Example 1.41. dlg_isflagset usage
...
if(dlg_isflagset("1"))
{
    ...
}
...

1.6.6.  dlg_setflag(flag)

   Set the dialog flag.

   Meaning of the parameters is as follows:
     * flag - index of the flag - can be pseudo-variable.

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

   Example 1.42. dlg_setflag usage
...
dlg_setflag("1");
...

1.6.7.  dlg_resetflag(flag)

   Reset the dialog flag.

   Meaning of the parameters is as follows:
     * flag - index of the flag - can be pseudo-variable.

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

   Example 1.43. dlg_resetflag usage
...
redlg_setflag("1");
...

1.6.8.  dlg_bye(side)

   Send BYE to parties in dialog.

   Meaning of the parameters is as follows:
     * side - where to send the BYE. It can be: caller, callee or
       all.

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

   Example 1.44. dlg_bye usage
...
dlg_bye("all");
...

1.6.9.  dlg_refer(side, address)

   Refer the 'side' to a new SIP 'address'.

   Meaning of the parameters is as follows:
     * side - which part to REFER. It can be: caller or callee.
     * address - SIP address to refer to.

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

   Example 1.45. dlg_refer usage
...
dlg_refer("caller", "sip:annoucement@kamailio.org");
...

1.6.10.  dlg_manage()

   Process current SIP request with dialog module. It is
   alternative to setting dialog flag for initial INVITE and
   Route-parameter-callback execution for within-dialog requests.

   This function can be used from REQUEST_ROUTE.

   Example 1.46. dlg_manage usage
...
modparam("dialog", "default_timeout", 100)
...
route {
...
    if(is_method("INVITE") && !has_totag())
    {
        $dlg_ctx(timeout_route) = 12;
        $dlg_ctx(timeout_bye) = 1;
    }
    dlg_manage();
...
}
...

1.6.11.  dlg_bridge(from, to, op)

   Bridge 'from' SIP address to 'to' SIP address via outbound
   proxy 'op'.

   Meaning of the parameters is as follows:
     * from - SIP address of first side to call.
     * to - SIP address to refer 'from' to.
     * op - outbound proxy SIP address.

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

   Example 1.47. dlg_bridge usage
...
dlg_bridge("sip:user@kamailio.org", "sip:annoucement@kamailio.org",
   "sip:kamailio.org:5080");
...

1.6.12.  dlg_get(callid, ftag, ttag)

   Search and set current dialog based on Call-ID, From-Tag and
   To-Tag parameters.

   Meaning of the parameters is as follows:
     * callid - SIP call-id.
     * ftag - SIP From tag.
     * ttag - SIP To tag.

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

   Example 1.48. dlg_get usage
...
if(dlg_get("abcdef", "123", "456"))
{
        dlg_bye("all");
}
...

1.7. Exported statistics

1.7.1. active_dialogs

   Returns the number of current active dialogs (may be confirmed
   or not).

1.7.2. early_dialogs

   Returns the number of early dialogs.

1.7.3. processed_dialogs

   Returns the total number of processed dialogs (terminated,
   expired or active) from the startup.

1.7.4. expired_dialogs

   Returns the total number of expired dialogs from the startup.

1.7.5. failed_dialogs

   Returns the number of failed dialogs.

1.8. Exported MI Functions

1.8.1. dlg_list

   Lists the description of a dialog or of all dialogs (calls). If
   only one dialogs is to be listed, the dialog identifiers are to
   be passed as parameter (callid and fromtag).

   Name: dlg_list

   Parameters:
     * callid (optional) - callid if a single dialog to be listed.
     * from_tag (optional, but cannot be present without the
       callid parameter) - fromtag (as per initial request) of the
       dialog to be listed. Note that if the from_tag is not
       specified, only dialogs created by a request without a from
       tag are matched, which will only occur with broken clients
       and is thus a very rare situation.

   MI FIFO Command Format:
                :dlg_list:_reply_fifo_file_
                _empty_line_

                :dlg_list:_reply_fifo_file_
                abcdrssfrs122444@192.168.1.1
                AAdfeEFF33

1.8.2. dlg_list_ctx

   The same as the "dlg_list" but including in the dialog
   description the associated context from modules sitting on top
   of the dialog module.

   Name: dlg_list_ctx

   Parameters: see "dlg_list"

   MI FIFO Command Format:
                :dlg_list_ctx:_reply_fifo_file_
                _empty_line_

1.8.3. dlg_end_dlg

   Terminates an ongoing dialog by sending BYE in both directions.

   Name: dlg_end_dlg

   Parameters:
     * h_entry - hash entry of the dialog in the internal dialog
       table
     * h_id - hash id of the dialog on the hash entry
     * extra_hdrs - (optional) string containg extra headers (full
       format) to be added to the BYE requests.

   The values for the h_entry and h_id can be get via the dlg_list
   MI command.

   MI FIFO Command Format:
                :dlg_end_dlg:_reply_fifo_file_
                342
                56
                _empty_line_

1.8.4. profile_get_size

   Returns the number of dialogs belonging to a profile. If the
   profile supports values, the check can be reinforced to take
   into account a specific value - how many dialogs were inserted
   into the profile with a specific value. If no value is passed,
   only simply belonging of the dialog to the profile is checked.
   Note that if the profile does not supports values, this will be
   silently discarded.

   Name: profile_get_size

   Parameters:
     * profile - name of the profile to get the value for.
     * value (optional)- string value to further restrict the
       check;

   MI FIFO Command Format:
                :profile_get_size:_reply_fifo_file_
                inbound_calls
                _empty_line_

1.8.5. profile_list_dlgs

   Lists all the dialogs belonging to a profile. If the profile
   supports values, the check can be reinforced to take into
   account a specific value - list only the dialogs that were
   inserted into the profile with that specific value. If no value
   is passed, all dialogs belonging to the profile will be listed.
   Note that the profile does not supports values, this will be
   silently discarded.

   Name: profile_list_dlgs

   Parameters:
     * profile - name of the profile to list the dialog for.
     * value (optional)- string value to further restrict the
       check;

   MI FIFO Command Format:
                :profile_list_dlgs:_reply_fifo_file_
                inbound_calls
                _empty_line_

1.8.6. dlg_bridge

   Bridge two SIP addresses in a call using INVITE(hold)-REFER-BYE
   mechanism.

   Name: dlg_bridge

   Parameters:
     * from - SIP address to initiate the call
     * to - SIP address to refer 'from' to
     * op (optional) - outbound proxy SIP address

   MI FIFO Command Format:
                :dlg_bridge:_reply_fifo_file_
                from
                to
                op
                _empty_line_

1.9. Exported pseudo-variables

1.9.1. $DLG_count

   Returns the number of current active dialogs (may be confirmed
   or not).

1.9.2. $DLG_status

   Returns the status of the dialog corresponding to the processed
   sequential request. This PV will be available only for
   sequential requests, after doing loose_route().

   Value may be:
     * NULL - Dialog not found.
     * 3 - Confirmed by a final reply but no ACK received yet.
     * 4 - Confirmed by a final reply and ACK received.
     * 5 - Dialog ended.

1.9.3. $DLG_lifetime

   Returns the duration (in seconds) of the dialog corresponding
   to the processed sequential request. The duration is calculated
   from the dialog confirmation and the current moment. This PV
   will be available only for sequential requests, after doing
   loose_route().

   NULL will be returned if there is no dialog for the request.

1.9.4. $dlg(...)

   Access to dialog attributes.

1.9.5. $dlg_ctx(...)

   Access to dialog context attributes.

Chapter 2. Developer Guide

2.1. Available Functions

2.1.1.  register_dlgcb (dialog, type, cb, param, free_param_cb)

   Register a new callback to the dialog.

   Meaning of the parameters is as follows:
     * struct dlg_cell* dlg - dialog to register callback to. If
       maybe NULL only for DLGCB_CREATED callback type, which is
       not a per dialog type.
     * int type - types of callbacks; more types may be register
       for the same callback function; only DLGCB_CREATED must be
       register alone. Possible types:
          + DLGCB_LOADED
          + DLGCB_CREATED - called when a new dialog is created -
            it's a global type (not associated to any dialog)
          + DLGCB_FAILED - called when the dialog was negatively
            replied (non-2xx) - it's a per dialog type.
          + DLGCB_CONFIRMED - called when the dialog is confirmed
            (2xx replied) - it's a per dialog type.
          + DLGCB_REQ_WITHIN - called when the dialog matches a
            sequential request - it's a per dialog type.
          + DLGCB_TERMINATED - called when the dialog is
            terminated via BYE - it's a per dialog type.
          + DLGCB_EXPIRED - called when the dialog expires without
            receiving a BYE - it's a per dialog type.
          + DLGCB_EARLY - called when the dialog is created in an
            early state (18x replied) - it's a per dialog type.
          + DLGCB_RESPONSE_FWDED - called when the dialog matches
            a reply to the initial INVITE request - it's a per
            dialog type.
          + DLGCB_RESPONSE_WITHIN - called when the dialog matches
            a reply to a subsequent in dialog request - it's a per
            dialog type.
          + DLGCB_MI_CONTEXT - called when the mi dlg_list_ctx
            command is invoked - it's a per dialog type.
          + DLGCB_DESTROY
     * dialog_cb cb - callback function to be called. Prototype
       is: "void (dialog_cb) (struct dlg_cell* dlg, int type,
       struct dlg_cb_params * params); "
     * void *param - parameter to be passed to the callback
       function.
     * param_free callback_param_free - callback function to be
       called to free the param. Prototype is: "void
       (param_free_cb) (void *param);"

Chapter 3. Frequently Asked Questions

   3.1.

       What happend with "use_tight_match" parameter?

       The parameter was removed with version 1.3 as the option of
       tight matching became mandatory and not configurable. Now, the
       tight matching is done all the time (when using DID matching).

   3.2.

       Where can I find more about Kamailio?

       Take a look at http://www.kamailio.org/.

   3.3.

       Where can I post a question about this module?

       First at all check if your question was already answered on one
       of our mailing lists:
         * User Mailing List -
           http://lists.kamailio.org/cgi-bin/mailman/listinfo/users
         * Developer Mailing List -
           http://lists.kamailio.org/cgi-bin/mailman/listinfo/devel

       E-mails regarding any stable Kamailio release should be sent to
       <users@lists.kamailio.org> and e-mails regarding development
       versions should be sent to <devel@lists.kamailio.org>.

       If you want to keep the mail private, send it to
       <team@lists.kamailio.org>.

   3.4.

       How can I report a bug?

       Please follow the guidelines provided at:
       http://sourceforge.net/tracker/?group_id=139143.
