The ngx_http_charset_module module adds the specified charset to the “Content-Type” response header field. In addition, the module can convert data from one charset to another, with some limitations:

• conversion is performed one way — from server to client,
• only single-byte charsets can be converted
• or single-byte charsets to/from UTF-8.

include        conf/koi-win;

charset        windows-1251;
source_charset koi8-r;

charset off;

Adds the specified charset to the “Content-Type” response header field. If this charset is different from the charset specified in the source_charset directive, a conversion is performed.

The parameter off cancels the addition of charset to the “Content-Type” response header field.

A charset can be defined with a variable:

charset $charset;

In such a case, all possible values of a variable need to be present in the configuration at least once in the form of the charset_map, charset, or source_charset directives. For utf-8, windows-1251, and koi8-r charsets it is sufficient to include the files conf/koi-win, conf/koi-utf, and conf/win-utf into configuration. For other charsets, simply making a fictitious conversion table works, for example:

charset_map iso-8859-5 _ { }

In addition, charset can also be set in the “X-Accel-Charset” response header field. This ability can be disabled using the proxy_ignore_headers and fastcgi_ignore_headers directives.

Describes the conversion table from one charset to another. A reverse conversion table is built using the same data. Character codes are given in hexadecimal. Missing characters in the range 80-FF are replaced with “?”. When converting from UTF-8, characters missing in a one-byte charset are replaced with “&#XXXX;”.

Example:

charset_map koi8-r windows-1251 {
    C0 FE ; # small yu
    C1 E0 ; # small a
    C2 E1 ; # small b
    C3 F6 ; # small ts
    ...
}

When describing a conversion table to UTF-8, codes for the UTF-8 charset should be given in the second column, for example:

charset_map koi8-r utf-8 {
    C0 D18E ; # small yu
    C1 D0B0 ; # small a
    C2 D0B1 ; # small b
    C3 D186 ; # small ts
    ...
}

Full conversion tables from koi8-r to windows-1251, and from koi8-r and windows-1251 to utf-8 are provided in the distribution files conf/koi-win, conf/koi-utf, and conf/win-utf.

charset_types text/html text/xml text/plain text/vnd.wap.wml
application/x-javascript application/rss+xml;

Enables module processing in responses with the specified MIME types in addition to “text/html”. The special value “*” matches any MIME type (0.8.29).

override_charset off;

Determines if a conversion should be performed for answers received from a proxied or FastCGI server, if the answers already carry a charset in the “Content-Type” response header field. If conversion is enabled, a charset specified in the received response is used as a source charset.

It should be noted that if a response was received in a subrequest then conversion from the response charset to the main request charset is always performed regardless of the override_charset directive setting.

Defines the source charset of a response. If this charset is different from the charset specified in the charset directive, a conversion is performed.