Пункт 193. Apache Module mod_setenvif
| Description: | Allows the setting of environment variables based
on characteristics of the request |
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| Status: | Base |
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| Module Identifier: | setenvif_module |
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| Source File: | mod_setenvif.c |
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Summary
The mod_setenvif module allows you to set
internal environment variables according to whether different aspects of
the request match regular expressions you specify. These
environment variables can be used by other parts of the server
to make decisions about actions to be taken, as well as becoming
available to CGI scripts and SSI pages.
The directives are considered in the order they appear in
the configuration files. So more complex sequences can be used,
such as this example, which sets netscape if the
browser is mozilla but not MSIE.
BrowserMatch ^Mozilla netscape
BrowserMatch MSIE !netscape
When the server looks up a path via an internal
subrequest such as looking
for a DirectoryIndex
or generating a directory listing with mod_autoindex ,
per-request environment variables are not inherited in the
subrequest. Additionally,
SetEnvIf directives
are not separately evaluated in the subrequest due to the API phases
mod_setenvif takes action in.
BrowserMatch Directive
| Description: | Sets environment variables conditional on HTTP User-Agent
|
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| Syntax: | BrowserMatch regex [!]env-variable[=value]
[[!]env-variable[=value]] ... |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | FileInfo |
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| Status: | Base |
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| Module: | mod_setenvif |
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The BrowserMatch is a special cases of the
SetEnvIf directive that
sets environment variables conditional on the
User-Agent HTTP request header. The following two
lines have the same effect:
BrowserMatch Robot is_a_robot
SetEnvIf User-Agent Robot is_a_robot
Some additional examples:
BrowserMatch ^Mozilla forms jpeg=yes browser=netscape
BrowserMatch "^Mozilla/[2-3]" tables agif frames javascript
BrowserMatch MSIE !javascript
BrowserMatchNoCase Directive
| Description: | Sets environment variables conditional on User-Agent without
respect to case |
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| Syntax: | BrowserMatchNoCase regex [!]env-variable[=value]
[[!]env-variable[=value]] ... |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | FileInfo |
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| Status: | Base |
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| Module: | mod_setenvif |
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The BrowserMatchNoCase directive is
semantically identical to the BrowserMatch directive.
However, it provides for case-insensitive matching. For
example:
BrowserMatchNoCase mac platform=macintosh
BrowserMatchNoCase win platform=windows
The BrowserMatch and
BrowserMatchNoCase directives are special cases of
the SetEnvIf and SetEnvIfNoCase
directives. The following two lines have the same effect:
BrowserMatchNoCase Robot is_a_robot
SetEnvIfNoCase User-Agent Robot is_a_robot
SetEnvIf Directive
| Description: | Sets environment variables based on attributes of the request
|
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| Syntax: | SetEnvIf attribute
regex [!]env-variable[=value]
[[!]env-variable[=value]] ... |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | FileInfo |
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| Status: | Base |
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| Module: | mod_setenvif |
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The SetEnvIf directive defines
environment variables based on attributes of the request. The
attribute specified in the first argument can be one of four
things:
- An HTTP request header field (see RFC2616
for more information about these); for example:
Host ,
User-Agent , Referer , and
Accept-Language . A regular expression may be
used to specify a set of request headers.
- One of the following aspects of the request:
-
Remote_Host - the hostname (if available) of
the client making the request
-
Remote_Addr - the IP address of the client
making the request
-
Server_Addr - the IP address of the server
on which the request was received (only with versions later
than 2.0.43)
-
Request_Method - the name of the method
being used ( GET , POST , et
cetera)
-
Request_Protocol - the name and version of
the protocol with which the request was made (e.g.,
"HTTP/0.9", "HTTP/1.1", etc.)
-
Request_URI - the resource requested on the HTTP
request line -- generally the portion of the URL
following the scheme and host portion without the query string. See
the RewriteCond
directive of mod_rewrite for extra information on
how to match your query string.
- The name of an environment variable in the list of those
associated with the request. This allows
SetEnvIf directives to test against the result
of prior matches. Only those environment variables defined by earlier
SetEnvIf[NoCase] directives are available for testing in
this manner. 'Earlier' means that they were defined at a broader scope
(such as server-wide) or previously in the current directive's scope.
Environment variables will be considered only if there was no match
among request characteristics and a regular expression was not
used for the attribute.
The second argument (regex) is a regular expression. If the regex
matches against the attribute, then the remainder of the
arguments are evaluated.
The rest of the arguments give the names of variables to set, and
optionally values to which they should be set. These take the form
of
-
varname , or
-
!varname , or
-
varname=value
In the first form, the value will be set to "1". The second
will remove the given variable if already defined, and the
third will set the variable to the literal value given by
value . Since version 2.0.51, Apache httpd will
recognize occurrences of $1 .. $9 within
value and replace them by parenthesized subexpressions
of regex. $0 provides access to the whole
string matched by that pattern.
SetEnvIf Request_URI "\.gif$" object_is_image=gif
SetEnvIf Request_URI "\.jpg$" object_is_image=jpg
SetEnvIf Request_URI "\.xbm$" object_is_image=xbm
SetEnvIf Referer www\.mydomain\.example\.com intra_site_referral
SetEnvIf object_is_image xbm XBIT_PROCESSING=1
SetEnvIf Request_URI "\.(.*)$" EXTENSION=$1
SetEnvIf ^TS ^[a-z] HAVE_TS
The first three will set the environment variable
object_is_image if the request was for an image
file, and the fourth sets intra_site_referral if
the referring page was somewhere on the
www.mydomain.example.com Web site.
The last example will set environment variable
HAVE_TS if the request contains any headers that
begin with "TS" whose values begins with any character in the
set [a-z].
See also
- Environment Variables in Apache HTTP Server,
for additional examples.
SetEnvIfExpr Directive
| Description: | Sets environment variables based on an ap_expr expression |
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| Syntax: | SetEnvIfExpr expr
[!]env-variable[=value]
[[!]env-variable[=value]] ... |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | FileInfo |
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| Status: | Base |
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| Module: | mod_setenvif |
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The SetEnvIfExpr directive defines
environment variables based on an <If>
ap_expr . These expressions will be evaluated at runtime,
and applied env-variable in the same fashion as SetEnvIf .
SetEnvIfExpr "tolower(req('X-Sendfile')) == 'd:\images\very_big.iso')" iso_delivered
This would set the environment variable iso_delivered
every time our application attempts to send it via X-Sendfile
A more useful example would be to set the variable rfc1918 if the
remote IP address is a private address according to RFC 1918:
SetEnvIfExpr "-R '10.0.0.0/8' || -R '172.16.0.0/12' || -R '192.168.0.0/16'" rfc1918
See also
- Expressions in Apache HTTP Server,
for a complete reference and more examples.
-
<If> can be used to achieve similar
results.
-
mod_filter
SetEnvIfNoCase Directive
| Description: | Sets environment variables based on attributes of the request
without respect to case |
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| Syntax: | SetEnvIfNoCase attribute regex
[!]env-variable[=value]
[[!]env-variable[=value]] ... |
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| Context: | server config, virtual host, directory, .htaccess |
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| Override: | FileInfo |
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| Status: | Base |
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| Module: | mod_setenvif |
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The SetEnvIfNoCase is semantically identical to
the SetEnvIf directive,
and differs only in that the regular expression matching is
performed in a case-insensitive manner. For example:
SetEnvIfNoCase Host Example\.Org site=example
This will cause the site environment variable
to be set to " example " if the HTTP request header
field Host: was included and contained
Example.Org , example.org , or any other
combination.
