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ProFTPD module mod_sql_odbc
ProFTPD module mod_sql_odbc
ODBC means Open Database Connectivity, and defines
a standard way of connecting to a database server such as MySQL, Postgres,
SQL Server, Oracle, etc. Many of the these databases also provide
their own native APIs for connectivity, in addition to supporting ODBC. Other
databases provide ODBC support, but no support for native connectivity.
The ProFTPD distribution includes the mod_sql_mysql module for
talking to a MySQL database using the native MySQL API, and a
mod_sql_postgres for connecting to Postgres databases using the
native Postgres API. However, there was no support for databases other
than these -- until now. The purpose of the mod_sql_odbc module
is to allow ProFTPD's mod_sql module to connect to any
database that supports ODBC. This module also allows proftpd to work with
databases that may already provide APIs for native connectivity, but for
which a specific mod_sql has not yet been developed.
This module is contained in the mod_sql_odbc.c file for
ProFTPD 1.3.x, and is not compiled by default. Installation
instructions are discussed here.
The most current version of mod_sql_odbc is distributed with
ProFTPD.
Author
Please contact TJ Saunders <tj at castaglia.org> with any
questions, concerns, or suggestions regarding this module.
Directives
Syntax: SQLODBCVersion version
Default: SQLODBCVersion ODBCv3
Context: server config, <VirtualHost>, <Global>
Module: mod_sql_odbc
Compatibility: 1.3.6rc2 and later
The SQLODBCVersion directive configures the ODBC API
version that the ODBC driver should use/expect. The default is
"ODBCv3", i.e. ODBC version 3. Some drivers may have issues with the
default version; this can manifest as errors similar to the following in your
SQLLogFile:
message: '[unixODBC][Driver Manager]Driver does not support the requested version'
When this happens, you might try using an older version of ODBC, via:
SQLODBCVersion ODBCv2
The mod_sql_odbc relies on one of the two following libraries
for ODBC support:
http://www.iodbc.org
http://www.unixodbc.org
One of these ODBC libraries must be installed prior to using
mod_sql_odbc.
Follow the usual steps for using contrib modules in ProFTPD, making sure to
list mod_sql. Note that you will need to use the
LIBS environment variable for indicating which ODBC library
to link against.
For example, if you wish to use the unixODBC library, you would use:
$ ./configure LIBS=-lodbc --with-modules=mod_sql:mod_sql_odbc ...
$ make
$ make install
On the other hand, for using the iODBC library, the invocation is slightly
different, specifying a different library name:
$ ./configure LIBS=-liodbc --with-modules=mod_sql:mod_sql_odbc ...
$ make
$ make install
You may need to specify the location of the ODBC header and library files in
your configure command, e.g.:
$ ./configure \
LD_LIBRARY_PATH=/usr/local/odbc/lib \
LDFLAGS=-L/usr/local/odbc/lib \
LIBS=-lodbc \
--with-modules=mod_sql:mod_sql_odbc \
--with-includes=/usr/local/odbc/include \
--with-libraries=/usr/local/odbc/lib
Note: some of the following information is taken from:
http://www.mysql.com/products/myodbc/manual.html#Introduction_to_ODBC
What is ODBC?
ODBC (Open Data Base Connectivity) provides a way
for client programs to access a wide range of databases or data sources.
ODBC is a standardized API, developed according to the specifications of the
SQL Access Group, that allows one to connect to SQL databases. It defines a
set of function calls, error codes and data types that can be used to develop
database-independent applications. ODBC is usually used when database
independence, or simultaneous access to different data sources, is required.
For more information about ODBC, refer to:
http://www.microsoft.com/data/odbc/
When should mod_sql_odbc be used?
There are two cases where a site might need to use the mod_sql_odbc
module: when the site's database does not provide a native connectivity API
(e.g. FrontBase), and when the site's database does not have a
corresponding mod_sql_db module for it. For example,
ProFTPD does not have a mod_sql_oracle module. Using
mod_sql_odbc and an Oracle-provided ODBC driver would allow
a site to have proftpd communicate with their Oracle database.
How does ODBC work?
An ODBC driver is a dynamically loadable library that knows how to
talk to a specific database. Many databases come bundled with an ODBC
driver. The following lists where to find ODBC drivers for the popular
MySQL and Postgres databases:
- MySQL ODBC Driver (MyODBC)
- http://www.mysql.com/products/myodbc/
- Postgres ODBC Driver (psqlODBC)
- https://odbc.postgresql.org/
The ODBC driver manager is a library that manages communication between
the ODBC-aware application and ODBC drivers. Its main functionality includes:
- resolving Data Source Names (DSN)
- loading and unloading of the drivers
- processing ODBC function calls or passing them to the driver
The following lists some commonly used driver managers:
- iODBC ODBC Driver Manager for Unix
- http://www.iodbc.org
- unixODBC Driver Manager for Unix
- http://www.unixodbc.org
- Microsoft Windows ODBC Driver Manager
- http://www.microsoft.com/data/
Environment Variables
There are two environment variables that both the iODBC and unixODBC libraries
use: LD_LIBRARY_PATH and ODBCINI. The
ODBCINI environment variable specifies the configuration file
used by the library; this file specifies the driver to use, and any database
connection information that driver may need.The LD_LIBRARY_PATH
environment variable is used to tell the Driver Manager where it may find
the driver libraries. Note that on a Linux system, if the
/etc/ld.so.conf contains the directory where the ODBC driver
libraries live (and /sbin/ldconfig has been run), use of
the LD_LIBRARY_PATH setting may not be necessary.
Configuring ODBC
The hard part about using the iODBC or unixODBC Unix driver managers is
their configuration. Often in ODBC documentation you will mention of DSNs,
or Data Source Names. A data source identifies a path to data that can include
a network library, server, database, and other attributes. To connect to a data
source, the driver manager checks for specific connection information. This
specific connection information is recorded in a file usually called
"odbc.ini".
Example iODBC odbc.ini file:
[ODBC Data Sources]
mysql = MySQL ODBC Connector (MyODBC)
[mysql]
Driver = /usr/local/iodbc/lib/libmyodbc3.so
Description = MySQL Driver
Server = localhost
Database = proftpd
Port = 3306
Socket = /tmp/mysql.sock
Example unixODBC odbc.ini file:
[mysql]
Description = MySQL
Driver = mysql
Server = localhost
Database = proftpd
Port = 3306
Socket = /tmp/mysql.sock
More details on the contents of odbc.ini files, and the different
meanings of configuration options, can be found in the respective driver
manager documentation.
Configuring mod_sql_odbc
For the most part, mod_sql_odbc requires little configuration.
It relies on the ODBC driver managers, which in turn use the above
environment variables. This means that ODBCINI and
LD_LIBRARY_PATH can be set in the environment, before starting
proftpd, and mod_sql_odbc would then work. The
one required bit of information is the
SQLConnectInfo directive.
This directive needs to contain the name of the stanza in your
odbc.ini file which holds the configuration. Using the example
odbc.ini files above, you would need the following in your
proftpd.conf:
# Tells mod_sql to use mod_sql_odbc
SQLBackend odbc
# Tells mod_sql_odbc which odbc.ini stanza to use
SQLConnectInfo mysql
Starting with proftpd 1.2.10rc1, it is possible to use the SetEnv
configuration directives to set the environment variables directly in
the proftpd.conf file, which makes configuration more
centralized.
Example configuration using SetEnv:
<IfModule mod_sql_odbc.c>
SetEnv LD_LIBRARY_PATH /path/to/odbc/lib
SetEnv ODBCINI /path/to/odbc.ini
</IfModule>
Please contact the author directly with any questions or comments.
© Copyright 2003-2017 TJ Saunders
All Rights Reserved
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