DBTEXT Module

Daniel-Constantin Mierla

   <miconda@gmail.com>

Edited by

Daniel-Constantin Mierla

   <miconda@gmail.com>

   Copyright © 2003, 2004 FhG FOKUS
   Revision History
   Revision $Revision: 4630 $ $Date: 2008-08-06 12:08:33 +0200
                              (Mi, 06 Aug 2008) $
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview

              1.1.1. Design of dbtext engine
              1.1.2. Internal format of a dbtext table
              1.1.3. Existing limitations

        1.2. Dependencies

              1.2.1. Kamailio modules
              1.2.2. External libraries or applications

        1.3. Exported Parameters

              1.3.1. db_mode (integer)

        1.4. Exported Functions
        1.5. Installation and Running

              1.5.1. Using dbtext with basic Kamailio
                      configuration

   2. Developer Guide

   List of Examples

   1.1. Sample of a dbtext table
   1.2. Minimal Kamailio location dbtext table definition
   1.3. Minimal Kamailio subscriber dbtext table example
   1.4. Set db_mode parameter
   1.5. Load the dbtext module
   1.6. Definition of 'subscriber' table (one line)
   1.7. Definition of 'location' and 'aliases' tables (one line)
   1.8. Definition of 'version' table and sample records
   1.9. Configuration file

Chapter 1. Admin Guide

1.1. Overview

   The module implements a simplified database engine based on
   text files. It can be used by Kamailio DB interface instead of
   other database module (like MySQL).

   The module is meant for use in demos or small devices that do
   not support other DB modules. It keeps everything in memory and
   if you deal with large amount of data you may run quickly out
   of memory. Also, it has not implemented all standard database
   facilities (like order by), it includes minimal functionality
   to work properly (who knows ?!?) with Kamailio.

   NOTE: the timestamp is printed in an integer value from time_t
   structure. If you use it in a system that cannot do this
   conversion, it will fail (support for such situation is in
   to-do list).

   NOTE: even when is in non-caching mode, the module does not
   write back to hard drive after changes. In this mode, the
   module checks if the corresponding file on disk has changed,
   and reloads it. The write on disk happens at openser shut down.

1.1.1. Design of dbtext engine

   The dbtext database system architecture:
     * a database is represented by a directory in the local file
       system. NOTE: when you use dbtext in Kamailio, the database
       URL for modules must be the path to the directory where the
       table-files are located, prefixed by "dbtext://", e.g.,
       "dbtext:///var/dbtext/ser". If there is no "/" after
       "dbtext://" then "CFG_DIR/" is inserted at the beginning of
       the database path. So, either you provide an absolute path
       to database directory or a relative one to "CFG_DIR"
       directory.
     * a table is represented by a text file inside database
       directory.

1.1.2. Internal format of a dbtext table

   First line is the definition of the columns. Each column must
   be declared as follows:
     * the name of column must not include white spaces.
     * the format of a column definition is: name(type,attr).
     * between two column definitions must be a white space, e.g.,
       "first_name(str) last_name(str)".
     * the type of a column can be:
          + int - integer numbers.
          + double - real numbers with two decimals.
          + str - strings with maximum size of 4KB.
     * a column can have one of the attributes:
          + auto - only for 'int' columns, the maximum value in
            that column is incremented and stored in this field if
            it is not provided in queries.
          + null - accept null values in column fields.
          + if no attribute is set, the fields of the column
            cannot have null value.
     * each other line is a row with data. The line ends with
       "\n".
     * the fields are separated by ":".
     * no value between two ':' (or between ':' and start/end of a
       row) means "null" value.
     * next characters must be escaped in strings: "\n", "\r",
       "\t", ":".
     * 0 -- the zero value must be escaped too.

   Example 1.1. Sample of a dbtext table
...
id(int,auto) name(str) flag(double) desc(str,null)
1:nick:0.34:a\tgood\: friend
2:cole:-3.75:colleague
3:bob:2.50:
...

   Example 1.2. Minimal Kamailio location dbtext table definition
...
username(str) contact(str) expires(int) q(double) callid(str) cseq(int)
...

   Example 1.3. Minimal Kamailio subscriber dbtext table example
...
username(str) password(str) ha1(str) domain(str) ha1b(str)
suser:supasswd:xxx:alpha.org:xxx
...

1.1.3. Existing limitations

   This database interface don't support the data insertion with
   default values. All such values specified in the database
   template are ignored. So its advisable to specify all data for
   a column at insertion operations.

1.2. Dependencies

1.2.1. Kamailio modules

   The next modules must be loaded before this module:
     * none.

1.2.2. External libraries or applications

   The next libraries or applications must be installed before
   running Kamailio with this module:
     * none.

1.3. Exported Parameters

   None.

1.3.1. db_mode (integer)

   Set caching mode (0) or non-caching mode (1). In caching mode,
   data is loaded at startup. In non-caching mode, the module
   check every time a table is requested whether the corresponding
   file on disk has changed, and if yes, will re-load table from
   file.

   Default value is "0".

   Example 1.4. Set db_mode parameter
...
modparam("db_text", "db_mode", 1)
...

1.4. Exported Functions

   None.

1.5. Installation and Running

   Compile the module and load it instead of mysql or other DB
   modules.

   REMINDER: when you use dbtext in Kamailio, the database URL for
   modules must be the path to the directory where the table-files
   are located, prefixed by "dbtext://", e.g.,
   "dbtext:///var/dbtext/ser". If there is no "/" after
   "dbtext://" then "CFG_DIR/" is inserted at the beginning of the
   database path. So, either you provide an absolute path to
   database directory or a relative one to "CFG_DIR" directory.

   Example 1.5. Load the dbtext module
...
loadmodule "/path/to/kamailio/modules/db_text.so"
...
modparam("module_name", "database_URL", "text:///path/to/dbtext/database
")
...

1.5.1. Using dbtext with basic Kamailio configuration

   Here are the definitions for most important table as well as a
   basic configuration file to use dbtext with Kamailio. The table
   structures may change in time and you will have to adjust next
   examples. These are know to work with upcoming Kamailio v0.9.x

   You have to populate the table 'subscriber' by hand with user
   profiles in order to have authentication. To use with the given
   configuration file, the table files must be placed in the
   '/tmp/serdb' directory.

   Example 1.6. Definition of 'subscriber' table (one line)
...
username(str) domain(str) password(str) first_name(str) last_name(str) p
hone(str) email_address(str) datetime_created(int) datetime_modified(int
) confirmation(str) flag(str) sendnotification(str) greeting(str) ha1(st
r) ha1b(str) perms(str) allow_find(str) timezone(str,null) rpid(str,null
)
...

   Example 1.7. Definition of 'location' and 'aliases' tables (one
   line)
...
username(str) domain(str,null) contact(str,null) received(str) expires(i
nt,null) q(double,null) callid(str,null) cseq(int,null) last_modified(st
r) flags(int) user_agent(str) socket(str)
...

   Example 1.8. Definition of 'version' table and sample records
...
table_name(str) table_version(int)
subscriber:3
location:6
aliases:6
...

   Example 1.9. Configuration file
...
#
# $Id: README 4630 2008-08-07 09:15:08Z henningw $
#
# simple quick-start config script with dbtext
#

# ----------- global configuration parameters ------------------------

#debug=9         # debug level (cmd line: -dddddddddd)
#fork=yes
#log_stderror=no        # (cmd line: -E)

check_via=no    # (cmd. line: -v)
dns=no          # (cmd. line: -r)
rev_dns=no      # (cmd. line: -R)
children=4

listen=10.100.100.1
port=5060

# ------------------ module loading ----------------------------------

# use dbtext database
loadmodule "modules/dbtext/dbtext.so"

loadmodule "modules/sl/sl.so"
loadmodule "modules/tm/tm.so"
loadmodule "modules/rr/rr.so"
loadmodule "modules/maxfwd/maxfwd.so"
loadmodule "modules/usrloc/usrloc.so"
loadmodule "modules/registrar/registrar.so"
loadmodule "modules/textops/textops.so"
loadmodule "modules/textops/mi_fifo.so"

# modules for digest authentication
loadmodule "modules/auth/auth.so"
loadmodule "modules/auth_db/auth_db.so"

# ----------------- setting module-specific parameters ---------------

# -- mi_fifo params --

modparam("mi_fifo", "fifo_name", "/tmp/openser_fifo")

# -- usrloc params --

# use dbtext database for persistent storage
modparam("usrloc", "db_mode", 2)
modparam("usrloc|auth_db", "db_url", "dbtext:///tmp/openserdb")

# -- auth params --
#
modparam("auth_db", "calculate_ha1", 1)
modparam("auth_db", "password_column", "password")
modparam("auth_db", "user_column", "username")
modparam("auth_db", "domain_column", "domain")

# -- rr params --
# add value to ;lr param to make some broken UAs happy
modparam("rr", "enable_full_lr", 1)

# -------------------------  request routing logic -------------------

# main routing logic

route{
    # initial sanity checks -- messages with
    # max_forwards==0, or excessively long requests
    if (!mf_process_maxfwd_header("10")) {
        sl_send_reply("483","Too Many Hops");
        exit;
    };
    if (msg:len >=  max_len ) {
        sl_send_reply("513", "Message too big");
        exit;
    };

    # we record-route all messages -- to make sure that
    # subsequent messages will go through our proxy; that's
    # particularly good if upstream and downstream entities
    # use different transport protocol
    if (!method=="REGISTER") record_route();

    # subsequent messages withing a dialog should take the
    # path determined by record-routing
    if (loose_route()) {
        # mark routing logic in request
        append_hf("P-hint: rr-enforced\r\n");
        route(1);
        exit;
    };

    if (!uri==myself) {
        # mark routing logic in request
        append_hf("P-hint: outbound\r\n");
        route(1);
        exit;
    };

    # if the request is for other domain use UsrLoc
    # (in case, it does not work, use the following command
    # with proper names and addresses in it)
    if (uri==myself) {
        if (method=="REGISTER") {
            # digest authentication
            if (!www_authorize("", "subscriber")) {
                www_challenge("", "0");
                exit;
            };

            save("location");
            exit;
        };

        lookup("aliases");
        if (!uri==myself) {
            append_hf("P-hint: outbound alias\r\n");
            route(1);
            exit;
        };

        # native SIP destinations are handled using our USRLOC DB
        if (!lookup("location")) {
            sl_send_reply("404", "Not Found");
            exit;
        };
    };
    append_hf("P-hint: usrloc applied\r\n");
    route(1);
}

route[1]
{
    # send it out now; use stateful forwarding as it works reliably
    # even for UDP2TCP
    if (!t_relay()) {
        sl_reply_error();
    };
}


...

Chapter 2. Developer Guide

   Once you have the module loaded, you can use the API specified
   by Kamailio DB interface.
