1. PDT module

Elena-Ramona Modroiu

   Asipto

   Copyright © 2003 FhG FOKUS
     __________________________________________________________________

   1.1. Overview
   1.2. Dependencies

        1.2.1. SER Modules

   1.3. Parameters

        1.3.1. db_url (string)
        1.3.2. db_table (string)
        1.3.3. prefix_column (string)
        1.3.4. domain_column (string)
        1.3.5. prefix (string)
        1.3.6. hsize_2pow (integer)
        1.3.7. sync_time (integer)
        1.3.8. clean_time (integer)

   1.4. Functions

        1.4.1. prefix2domain(mode)

   1.5. FIFO Interface

1.1. Overview

   This module translates a numerical prefix into a domain and updates
   accordingly the request URI.

   The module looks up at the Request-URI part of a message and if the
   user part begins with an established prefix it will update the URI.
   Updating the uri consists of: remove the prefix from the user part of
   the uri and keep the rest as the user part of the new uri. The host and
   port are changed with the domain matched for the leading prefix.

   <prefix><userid><:password>@<mydomain.com> ...

   and the result will be:

   <userid><:password>@<domain[:port]>...

   Example 1. prefix-domain translation
prefix=123
domain[123]=alpha.org

sip:[email protected]  => sip:[email protected]

   The prefix could be prefixed by other digits. These digits will not be
   used to look up the domain (the classic example, 00 used for
   international calls, then follows the country prefix). For more
   information on this, see 'prefix' parameter.
     * A sample config file and the MySQL script to create the database
       needed by PDT are located in './doc/'.
     * Sample shell scripts to manage prefix-domain pairs are also located
       in './doc/' (pdt_fifo_add.sh, pdt_fifo_delete.sh,
       pdt_fifo_list.sh).

1.2. Dependencies

1.2.1. SER Modules

   The following modules must be loaded before this module:
     * A SER database module (e.g., mysql, dbtext).

1.3. Parameters

1.3.1. db_url (string)

   SQL URL of database--username, password, host, port and database (ex:
   mysql://username:[email protected]/database)

   Default value is 'mysql://[email protected]/pdt'.

   Example 2. Set db_url parameter
...
modparam("pdt", "db_url", "mysql://user:[email protected]/ser")
...

1.3.2. db_table (string)

   Table name.

   Default value is "prefix_domain".

   Example 3. Set db_table parameter
...
modparam("pdt", "db_table", "pdt")
...

1.3.3. prefix_column (string)

   Name of 'prefix' column.

   Default value is "prefix".

   Example 4. Set prefix_column parameter
...
modparam("pdt", "prefix_column", "code")
...

1.3.4. domain_column (string)

   Name of 'domain' column.

   Default value is "domain".

   Example 5. Set domain_column parameter
...
modparam("pdt", "domain_column", "hostname")
...

1.3.5. prefix (string)

   Default leading prefix who denotes what URI needs to be translated - if
   it is NULL the module will not check the Request-URI; against it and
   the PDT prefix is considered starting from the first digit. Otherwise,
   the module will check first if the Request-URI starts with it and will
   skip it to look up the domain.

   Default value is NULL.

   Example 6. Set prefix parameter
...
modparam("pdt", "prefix", "00")
...

1.3.6. hsize_2pow (integer)

   Number of the hash entries = 2^hash_size.

   Default value is 4.

   Example 7. Set hsize_2pow parameter
...
modparam("pdt", "hsize_2pow", 4)
...

1.3.7. sync_time (integer)

   Time in seconds to synchronize the cache of each process with the
   changes made through FIFO. Any prefix-domain change made through FIFO
   is guaranteed to have efect after this period of time past.

   Default value is 600.

   Example 8. Set sync_time parameter
...
modparam("pdt", "sync_time", 300)
...

1.3.8. clean_time (integer)

   Time in seconds to clean the changes inserted via FIFO. The changes
   will be removed from FIFO diff list only when all SER processes applied
   these changes.

   Default value is 900.

   Example 9. Set clean_time parameter
...
modparam("pdt", "clean_time", 600)
...

1.4. Functions

1.4.1.  prefix2domain(mode)

   Build a new URI if it is necessary. Returns 1 when the translation was
   made or there was nothing to translate (user part of the URI is empty,
   it does not match the prefix parameter or there is no domain associated
   with a possible prefix from user part). Returns -1 in error cases.

   The "mode" parameter specifies whether to strip or not the prefix from
   user part. If the parameter is missing or it has the value "0", then
   the prefix is removed along with the leading prefix. If the value is
   "1", only the leading prefix is removed. If the values is "2" the user
   part of the URI is not changed.

   Example 10. prefix2domain usage
...
prefix2domain();
...
prefix2domain("2");
...

1.5. FIFO Interface

   The modules uses only the cache to look up domains. If you want to add
   or delete a new prefix-domain pair you have to use FIFO commands. All
   changes made via FIFO are applied to database. The database is loaded
   only at SER start up time.

   There are three FIFO commands to use with PDT.
     * pdt_add - add a new prefix-domain pair
     * pdt_delete - remove a prefix-domain pair
     * pdt_list - list the prefixes and the domains

   Example shell scripts for these commands are placed in './doc/'
   (pdt_fifo_add.sh, pdt_fifo_delete.sh, pdt_fifo_list.sh). More about, in
   the comments before the implementation of the functions, inside the
   'pdt.c' file.