
usrloc Module

Jan Janak

   FhG FOKUS

Edited by

Jan Janak

   Copyright © 2003 FhG FOKUS
     _________________________________________________________

   Table of Contents
   1. User's Guide

        1.1. Overview
        1.2. Dependencies

              1.2.1. SER Modules
              1.2.2. External Libraries or Applications

        1.3. Exported Parameters

              1.3.1. user_column (string)
              1.3.2. domain_column (string)
              1.3.3. contact_column (string)
              1.3.4. expires_column (string)
              1.3.5. q_column (string)
              1.3.6. callid_column (string)
              1.3.7. cseq_column (string)
              1.3.8. method_column (string)
              1.3.9. flags_column (string)
              1.3.10. user_agent_column (string)
              1.3.11. received_column (string)
              1.3.12. user_agent_column (string)
              1.3.13. db_url (string)
              1.3.14. timer_interval (integer)
              1.3.15. use_domain (integer)
              1.3.16. desc_time_order (integer)
              1.3.17. db_mode (integer)

        1.4. Exported Functions

   2. Developer's Guide

        2.1. Available Functions

              2.1.1. ul_register_domain(name)
              2.1.2. ul_insert_urecord(domain, aor, rec)
              2.1.3. ul_delete_urecord(domain, aor)
              2.1.4. ul_get_urecord(domain, aor)
              2.1.5. ul_lock_udomain(domain)
              2.1.6. ul_unlock_udomain(domain)
              2.1.7. ul_release_urecord(record)
              2.1.8. ul_insert_ucontact(record, contact, expires,
                      q, callid, cseq, flags, cont, ua)

              2.1.9. ul_delete_ucontact(record, contact)
              2.1.10. ul_get_ucontact(record, contact)
              2.1.11. ul_get_all_ucontacts(buf, len, flags)
              2.1.12. ul_update_ucontact(contact, expires, q,
                      callid, cseq, set, res, ua)

        2.2. Contact states

   3. Frequently Asked Questions

   List of Figures
   2-1. States of a ucontact

   List of Examples
   1-1. Set user_column parameter
   1-2. Set contact_column parameter
   1-3. Set expires_column parameter
   1-4. Set q_column parameter
   1-5. Set callid_column parameter
   1-6. Set cseq_column parameter
   1-7. Set method_column parameter
   1-8. Set user_agent_column parameter
   1-9. Set received_column parameter
   1-10. Set db_url parameter
   1-11. Set timer_interval parameter
   1-12. Set db_mode parameter
     _________________________________________________________

Chapter 1. User's Guide

1.1. Overview

   User location module. The module keeps a user location table
   and provides access to the table to other modules. The module
   exports no functions that could be used directly from scripts.
     _________________________________________________________

1.2. Dependencies

1.2.1. SER Modules

   The following modules must be loaded before this module:

     * Optionally a database module.
     _________________________________________________________

1.2.2. External Libraries or Applications

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

     * None.
     _________________________________________________________

1.3. Exported Parameters

1.3.1. user_column (string)

   Name of column containing usernames.

   Default value is "username". 

   Example 1-1. Set user_column parameter
...
modparam("usrloc", "user_column", "username")
...
     _________________________________________________________

1.3.2. domain_column (string)

   Name of column containing domain parts.

   Default value is "domain". 
     _________________________________________________________

1.3.3. contact_column (string)

   Name of column containing contacts.

   Default value is "contact". 

   Example 1-2. Set contact_column parameter
...
modparam("usrloc", "contact_column", "contact")
...
     _________________________________________________________

1.3.4. expires_column (string)

   Name of column containing expires value.

   Default value is "expires". 

   Example 1-3. Set expires_column parameter
...
modparam("usrloc", "expires_column", "expires")
...
     _________________________________________________________

1.3.5. q_column (string)

   Name of column containing q values.

   Default value is "q". 

   Example 1-4. Set q_column parameter
...
modparam("usrloc", "q_column", "q")
...
     _________________________________________________________

1.3.6. callid_column (string)

   Name of column containing callid values.

   Default value is "callid". 

   Example 1-5. Set callid_column parameter
...
modparam("usrloc", "callid_column", "callid")
...
     _________________________________________________________

1.3.7. cseq_column (string)

   Name of column containing cseq numbers.

   Default value is "cseq". 

   Example 1-6. Set cseq_column parameter
...
modparam("usrloc", "cseq_column", "cseq")
...
     _________________________________________________________

1.3.8. method_column (string)

   Name of column containing supported methods.

   Default value is "method". 

   Example 1-7. Set method_column parameter
...
modparam("usrloc", "method_column", "method")
...
     _________________________________________________________

1.3.9. flags_column (string)

   Name of column containing saved flags.

   Default value is "flags". 
     _________________________________________________________

1.3.10. user_agent_column (string)

   Name of column containing user-agent values.

   Default value is "user_agent". 

   Example 1-8. Set user_agent_column parameter
...
modparam("usrloc", "user_agent_column", "user_agent")
...
     _________________________________________________________

1.3.11. received_column (string)

   Name of column containing the source IP, port, and protocol
   from the REGISTER message.

   Default value is "received". 

   Example 1-9. Set received_column parameter
...
modparam("usrloc", "received_column", "received")
...
     _________________________________________________________

1.3.12. user_agent_column (string)

   Name of column containing the user agent string.

   Default value is "user_agent". 
     _________________________________________________________

1.3.13. db_url (string)

   URL of the database that should be used.

   Default value is "mysql://ser:heslo@localhost/ser". 

   Example 1-10. Set db_url parameter
...
modparam("usrloc", "db_url", "mysql://username:password@localhost/ser")
...
     _________________________________________________________

1.3.14. timer_interval (integer)

   Number of seconds between two timer runs. The module uses
   timer to delete expired contacts, synchronize with database
   and other tasks, that need to be run periodically.

   Default value is 60. 

   Example 1-11. Set timer_interval parameter
...
modparam("usrloc", "timer_interval", 120)
...
     _________________________________________________________

1.3.15. use_domain (integer)

   Use also the domain part, in addition to username, when
   searching for a record. This parameter must be enabled in
   multi-domain mode.

   Default value is 0 (disabled). 
     _________________________________________________________

1.3.16. desc_time_order (integer)

   Enable/disable sorting of contacts in descenting modification
   time order. This ensures that most fresh contacts come first
   when doing serial forking.

   Default value is 0 (disabled). 
     _________________________________________________________

1.3.17. db_mode (integer)

   The usrloc module can utilize database for persistent contact
   storage. If you use database, your contacts will survive
   machine restarts or SW crashes. The disadvantage is that
   accessing database can be very time consuming. Therefore,
   usrloc module implements three database accessing modes:

     * 0 - This disables database completely. Only memory will be
       used. Contacts will not survive restart. Use this value if
       you need a really fast usrloc and contact persistence is
       not necessary or is provided by other means.
     * 1 - Write-Through scheme. All changes to usrloc are
       immediately reflected in database too. This is very slow,
       but very reliable. Use this scheme if speed is not your
       priority but need to make sure that no registered contacts
       will be lost during crash or reboot.
     * 2 - Write-Back scheme. This is a combination of previous
       two schemes. All changes are made to memory and database
       synchronization is done in the timer. The timer deletes
       all expired contacts and flushes all modified or new
       contacts to database. Use this scheme if you encounter
       high-load peaks and want them to process as fast as
       possible. The mode will not help at all if the load is
       high all the time. Also, latency of this mode is much
       lower than latency of mode 1, but slightly higher than
       latency of mode 0.

   Warning

   In case of crash or restart contacts that are in memory only
   and haven't been flushed yet will get lost. If you want
   minimize the risk, use shorter timer interval.

   Default value is 0. 

   Example 1-12. Set db_mode parameter
...
modparam("usrloc", "db_mode", 2)
...
     _________________________________________________________

1.4. Exported Functions

   There are no exported functions that could be used in scripts.
     _________________________________________________________

Chapter 2. Developer's Guide

2.1. Available Functions

2.1.1. ul_register_domain(name)

   The function registers a new domain. Domain is just another
   name for table used in registrar. The function is called from
   fixups in registrar. It gets name of the domain as a parameter
   and returns pointer to a new domain structure. The fixup than
   'fixes' the parameter in registrar so that it will pass the
   pointer instead of the name every time save() or lookup() is
   called. Some usrloc functions get the pointer as parameter
   when called. For more details see implementation of save
   function in registrar.

   Meaning of the parameters is as follows:

     * const char* name - Name of the domain (also called table)
       to be registered.
     _________________________________________________________

2.1.2. ul_insert_urecord(domain, aor, rec)

   The function creates a new record structure and inserts it in
   the specified domain. The record is structure that contains
   all the contacts for belonging to the specified username.

   Meaning of the parameters is as follows:

     * udomain_t* domain - Pointer to domain returned by
       ul_register_udomain.

     * str* aor - Address of Record (aka username) of the new
       record (at this time the record will contain no contacts
       yet).

     * urecord_t** rec - The newly created record structure.
     _________________________________________________________

2.1.3. ul_delete_urecord(domain, aor)

   The function deletes all the contacts bound with the given
   Address Of Record.

   Meaning of the parameters is as follows:

     * udomain_t* domain - Pointer to domain returned by
       ul_register_udomain.

     * str* aor - Address of record (aka username) of the record,
       that should be deleted.
     _________________________________________________________

2.1.4. ul_get_urecord(domain, aor)

   The function returns pointer to record with given Address of
   Record.

   Meaning of the parameters is as follows:

     * udomain_t* domain - Pointer to domain returned by
       ul_register_udomain.

     * str* aor - Address of Record of request record.
     _________________________________________________________

2.1.5. ul_lock_udomain(domain)

   The function lock the specified domain, it means, that no
   other processes will be able to access during the time. This
   prevents race conditions. Scope of the lock is the specified
   domain, that means, that multiple domain can be accessed
   simultaneously, they don't block each other.

   Meaning of the parameters is as follows:

     * udomain_t* domain - Domain to be locked.
     _________________________________________________________

2.1.6. ul_unlock_udomain(domain)

   Unlock the specified domain previously locked by
   ul_lock_udomain.

   Meaning of the parameters is as follows:

     * udomain_t* domain - Domain to be unlocked.
     _________________________________________________________

2.1.7. ul_release_urecord(record)

   Do some sanity checks - if all contacts have been removed,
   delete the entire record structure.

   Meaning of the parameters is as follows:

     * urecord_t* record - Record to be released.
     _________________________________________________________

2.1.8. ul_insert_ucontact(record, contact, expires, q, callid, cseq,
flags, cont, ua)

   The function inserts a new contact in the given record with
   specified parameters.

   Meaning of the parameters is as follows:

     * urecord_t* record - Record in which the contact should be
       inserted.

     * str* contact - Contact URI.

     * time_t expires - Expires of the contact in absolute value.

     * float q - q value of the contact.

     * str* callid - Call-ID of the REGISTER message that
       contained the contact.

     * int cseq - CSeq of the REGISTER message that contained the
       contact.

     * unsigned int flags - Flags to be set.

     * ucontact_t* cont - Pointer to newly created structure.

     * str* ua - User-Agent of the REGISTER message that
       contained the contact.
     _________________________________________________________

2.1.9. ul_delete_ucontact(record, contact)

   The function deletes given contact from record.

   Meaning of the parameters is as follows:

     * urecord_t* record - Record from which the contact should
       be removed.

     * ucontact_t* contact - Contact to be deleted.
     _________________________________________________________

2.1.10. ul_get_ucontact(record, contact)

   The function tries to find contact with given Contact URI and
   returns pointer to structure representing the contact.

   Meaning of the parameters is as follows:

     * urecord_t* record - Record to be searched for the contact.

     * str_t* contact - URI of the request contact.
     _________________________________________________________

2.1.11. ul_get_all_ucontacts(buf, len, flags)

   The function retrieves all contacts of all registered users
   and returns them in the caller-supplied buffer. If the buffer
   is too small, the function returns positive value indicating
   how much additional space would be necessary to accommodate
   all of them. Please note that the positive return value should
   be used only as a "hint", as there is no guarantee that during
   the time between two subsequent calls number of registered
   contacts will remain the same.

   If flag parameter is set to non-zero value then only contacts
   that have the specified flags set will be returned. It is, for
   example, possible to list only contacts that are behind NAT.

   Meaning of the parameters is as follows:

     * void* buf - Buffer for returning contacts.

     * int len - Length of the buffer.

     * unsigned int flags - Flags that must be set.
     _________________________________________________________

2.1.12. ul_update_ucontact(contact, expires, q, callid, cseq, set,
res, ua)

   The function updates contact with new values.

   Meaning of the parameters is as follows:

     * ucontact_t* contact - Contact URI.

     * time_t expires - Expires of the contact in absolute value.

     * float q - q value of the contact.

     * str* callid - Call-ID of the REGISTER message that
       contained the contact.

     * int cseq - CSeq of the REGISTER message that contained the
       contact.

     * unsigned int set - OR value of flags to be set.

     * unsigned int res - OR value of flags to be reset.

     * str* ua - User-Agent of the REGISTER message that
       contained the contact.
     _________________________________________________________

2.2. Contact states

   Figure 2-1. States of a ucontact

   [usrloc_states_w_zombie.png]

   Contacts in one of the zombie states should be ignored by any
   function which interacts with an external user. Contacts are
   only kept in a zombie state to store the informations for
   replication. Contacts can also appear in a zombie state even
   if no replication is used, but in this case the contacts
   should be removed by the next timer event automatically.
     _________________________________________________________

Chapter 3. Frequently Asked Questions

   3.1. Where can I find more about SER?
   3.2. Where can I post a question about this module?
   3.3. How can I report a bug?

   3.1. Where can I find more about SER?

   Take a look at http://iptel.org/ser.

   3.2. 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:

     * http://mail.iptel.org/mailman/listinfo/serusers
     * http://mail.iptel.org/mailman/listinfo/serdev

   E-mails regarding any stable version should be sent to
   <serusers@iptel.org> and e-mail regarding development versions
   or CVS snapshots should be send to <serdev@iptel.org>.

   If you want to keep the mail private, send it to
   <serhelp@iptel.org>.

   3.3. How can I report a bug?

   Please follow the guidelines provided at:
   http://iptel.org/ser/bugs
