Daniel-Constantin Mierla

Edited by

Daniel-Constantin Mierla

Revision History
Revision $Revision$ $Date$

Table of Contents

1. Admin Guide
1. Overview
1.1. Design of dbtext engine
1.2. Internal format of a dbtext table
1.3. Existing limitations
2. Dependencies
2.1. Kamailio modules
2.2. External libraries or applications
3. Exported Parameters
3.1. db_mode (integer)
4. Exported Functions
5. Installation and Running
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. 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. 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 “text://”, e.g., “text:///var/dbtext/ser”. If there is no “/” after “text://” 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.

1.2. 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

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)

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.

2. Dependencies

2.1. Kamailio modules

The next modules must be loaded before this module:

  • none.

2.2. External libraries or applications

The next libraries or applications must be installed before running Kamailio with this module:

  • none.

3. Exported Parameters


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)

4. Exported Functions


5. Installation and Running

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

REMINDER: when you use text in Kamailio, the database URL for modules must be the path to the directory where the table-files are located, prefixed by “text://”, e.g., “text:///var/dbtext/ser”. If there is no “/” after “text://” 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_k/db_text.so"
modparam("module_name", "db_url", "text:///path/to/dbtext/database")

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) phone(str) email_address(str) datetime_created(int) datetime_modified(int) confirmation(str) flag(str) sendnotification(str) greeting(str) ha1(str) 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(int,null) q(double,null) callid(str,null) cseq(int,null) last_modified(str) flags(int) user_agent(str) socket(str) 

Example 1.8. Definition of 'version' table and sample records

table_name(str) table_version(int)

Example 1.9. Configuration file

# $Id$
# simple quick-start config script with dbtext

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

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

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


# ------------------ 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

    # 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");
    if (msg:len >=  max_len ) {
        sl_send_reply("513", "Message too big");

    # 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");

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

    # 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");


        if (!uri==myself) {
            append_hf("P-hint: outbound alias\r\n");

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

    # send it out now; use stateful forwarding as it works reliably
    # even for UDP2TCP
    if (!t_relay()) {


Chapter 2. Developer Guide

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