mod_charset_lite Specify character set translation or recoding Extension mod_charset_lite.c charset_lite_module

mod_charset_lite allows the server to change the character set of responses before sending them to the client. In an EBCDIC environment, Apache always translates HTTP protocol content (e.g. response headers) from the code page of the Apache process locale to ISO-8859-1, but not the body of responses. In any environment, mod_charset_lite can be used to specify that response bodies should be translated. For example, if files are stored in EBCDIC, then mod_charset_lite can translate them to ISO-8859-1 before sending them to the client.

This module provides a small subset of configuration mechanisms implemented by Russian Apache and its associated mod_charset.
Common Problems
Invalid character set names

The character set name parameters of CharsetSourceEnc and CharsetDefault must be acceptable to the translation mechanism used by APR on the system where mod_charset_lite is deployed. These character set names are not standardized and are usually not the same as the corresponding values used in http headers. Currently, APR can only use iconv(3), so you can easily test your character set names using the iconv(1) program, as follows:

iconv -f charsetsourceenc-value -t charsetdefault-value
Mismatch between character set of content and translation rules

If the translation rules don't make sense for the content, translation can fail in various ways, including:

  • The translation mechanism may return a bad return code, and the connection will be aborted.
  • The translation mechanism may silently place special characters (e.g., question marks) in the output buffer when it cannot translate the input buffer.
CharsetSourceEnc Source charset of files CharsetSourceEnc charset server config virtual hostdirectory .htaccess FileInfo

The CharsetSourceEnc directive specifies the source charset of files in the associated container.

The value of the charset argument must be accepted as a valid character set name by the character set support in APR. Generally, this means that it must be supported by iconv.

Example <Directory /export/home/trawick/apacheinst/htdocs/convert>
CharsetSourceEnc UTF-16BE
CharsetDefault ISO-8859-1
 </Directory>

The character set names in this example work with the iconv translation support in Solaris 8.

Specifying the same charset for both CharsetSourceEnc and CharsetDefault disables translation. The charset need not match the charset of the response, but it must be a valid charset on the system. CharsetDefault Charset to translate into CharsetDefault charset server config virtual hostdirectory .htaccess FileInfo

The CharsetDefault directive specifies the charset that content in the associated container should be translated to.

The value of the charset argument must be accepted as a valid character set name by the character set support in APR. Generally, this means that it must be supported by iconv.

Example <Directory /export/home/trawick/apacheinst/htdocs/convert>
CharsetSourceEnc UTF-16BE
CharsetDefault ISO-8859-1
 </Directory> Specifying the same charset for both CharsetSourceEnc and CharsetDefault disables translation. The charset need not match the charset of the response, but it must be a valid charset on the system. CharsetOptions Configures charset translation behavior CharsetOptions option [option] ... CharsetOptions DebugLevel=0 ImplicitAdd server config virtual hostdirectory .htaccess FileInfo

The CharsetOptions directive configures certain behaviors of mod_charset_lite. Option can be one of

DebugLevel=n
The DebugLevel keyword allows you to specify the level of debug messages generated by mod_charset_lite. By default, no messages are generated. This is equivalent to DebugLevel=0. With higher numbers, more debug messages are generated, and server performance will be degraded. The actual meanings of the numeric values are described with the definitions of the DBGLVL_ constants near the beginning of mod_charset_lite.c.
ImplicitAdd | NoImplicitAdd
The ImplicitAdd keyword specifies that mod_charset_lite should implicitly insert its filter when the configuration specifies that the character set of content should be translated. If the filter chain is explicitly configured using the AddOutputFilter directive, NoImplicitAdd should be specified so that mod_charset_lite doesn't add its filter.
TranslateAllMimeTypes | NoTranslateAllMimeTypes
Normally, mod_charset_lite will only perform translation on a small subset of possible mimetypes. When the TranslateAllMimeTypes keyword is specified for a given configuration section, translation is performed without regard for mimetype.