Apache Module mod_charset_lite

Description: Specify character set translation or recoding
Status: Extension
ModuleIdentifier: charset_lite_module
SourceFile: mod_charset_lite.c

Summary

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.

CharsetDefault Directive

Description: Charset to translate into
Syntax: 
CharsetDefault charset
Context: server config, virtual host, directory, .htaccess
Override: FileInfo
Status: Extension
Module: mod_charset_lite

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 Directive

Description: Configures charset translation behavior
Syntax: 
CharsetOptions option [option] ...
Default: 
CharsetOptions ImplicitAdd
Context: server config, virtual host, directory, .htaccess
Override: FileInfo
Status: Extension
Module: mod_charset_lite

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

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.

CharsetSourceEnc Directive

Description: Source charset of files
Syntax: 
CharsetSourceEnc charset
Context: server config, virtual host, directory, .htaccess
Override: FileInfo
Status: Extension
Module: mod_charset_lite

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.

© 2018 The Apache Software Foundation
Licensed under the Apache License, Version 2.0.
https://httpd.apache.org/docs/2.4/en/mod/mod_charset_lite.html