1. Usrloc Module

Jan Janak

   FhG FOKUS

   Copyright © 2003 FhG FOKUS
     __________________________________________________________________

   1.1. Overview
   1.2. Dependencies
   1.3. Parameters

        1.3.1. user_column (string)
        1.3.2. contact_column (string)
        1.3.3. expires_column (string)
        1.3.4. q_column (string)
        1.3.5. callid_column (string)
        1.3.6. cseq_column (string)
        1.3.7. method_column (string)
        1.3.8. user_agent_column (string)
        1.3.9. received_column (string)
        1.3.10. db_url (string)
        1.3.11. timer_interval (integer)
        1.3.12. db_mode (integer)

   1.4. Usrloc Module API

        1.4.1. ul_register_domain(name)
        1.4.2. ul_insert_urecord(domain, aor, rec)
        1.4.3. ul_delete_urecord(domain, aor)
        1.4.4. ul_get_urecord(domain, aor)
        1.4.5. ul_lock_udomain(domain)
        1.4.6. ul_unlock_udomain(domain)
        1.4.7. ul_release_urecord(record)
        1.4.8. ul_insert_ucontact(record, contact, expires, q, callid,
                cseq, flags, cont, ua)

        1.4.9. ul_delete_ucontact(record, contact)
        1.4.10. ul_get_ucontact(record, contact)
        1.4.11. ul_get_all_ucontacts(buf, len, flags)
        1.4.12. ul_update_ucontact(contact, expires, q, callid, cseq, set,
                res, ua)

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

   The following modules must be loaded before this module:
     * Optionally a database module.

1.3. Parameters

1.3.1. user_column (string)

   Name of column containing usernames.

   Default value is "username".

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

1.3.2. contact_column (string)

   Name of column containing contacts.

   Default value is "contact".

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

1.3.3. expires_column (string)

   Name of column containing expires value.

   Default value is "expires".

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

1.3.4. q_column (string)

   Name of column containing q values.

   Default value is "q".

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

1.3.5. callid_column (string)

   Name of column containing callid values.

   Default value is "callid".

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

1.3.6. cseq_column (string)

   Name of column containing cseq numbers.

   Default value is "cseq".

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

1.3.7. method_column (string)

   Name of column containing supported methods.

   Default value is "method".

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

1.3.8. user_agent_column (string)

   Name of column containing user-agent values.

   Default value is "user_agent".

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

1.3.9. received_column (string)

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

   Default value is "received".

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

1.3.10. db_url (string)

   URL of the database that should be used.

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

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

1.3.11. 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 11. Set timer_interval parameter
...
modparam("usrloc", "timer_interval", 120)
...

1.3.12. 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 four 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.
     * 3 - Read-Only scheme. Disables commits to database. Upon start
       contacts are read from the database but changes are not written.
       Contacts will thus not survive a restart unless taken care of
       otherwise. Use this if you need the benefits of mode 0 with a
       databases backed preloading feature. Attention: There is a slight
       window where updated contacts might not make it into memory while
       reading and parsing contacts from the database before going into
       full production mode.

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 12. Set db_mode parameter
...
modparam("usrloc", "db_mode", 2)
...

1.4. Usrloc Module API

1.4.1.  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.

1.4.2.  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.

1.4.3.  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.

1.4.4.  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.

1.4.5.  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.

1.4.6.  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.

1.4.7.  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.

1.4.8.  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.

1.4.9.  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.

1.4.10.  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.

1.4.11.  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.

1.4.12.  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.