cac0964f155bdb6daba7ecf5628ed2fec3763275orlikowski<?xml version="1.0"?>

9a28fdd4b3e9d196cccecc6e1f3e05e23c4c4566orlikowski<!DOCTYPE modulesynopsis SYSTEM "/style/modulesynopsis.dtd">

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb<?xml-stylesheet type="text/xsl" href="/style/manual.en.xsl"?>

cb5d3f2f217d457dada4883addb1dc9f3f17bb85fielding

d66260b801a953237f71d6a4b26d8fd9ea419e3brbb

d66260b801a953237f71d6a4b26d8fd9ea419e3brbb<modulesynopsis metafile="mod_headers.xml.meta">

d66260b801a953237f71d6a4b26d8fd9ea419e3brbb

7aae0c3ef8e7f18f57e2712815c7b48358e5ff68rbb<name>mod_headers</name>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb<description>Customization of HTTP request and response

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbbheaders</description>

8a3a703eae0e35f674b189181609545c6fc77a09rbb<status>Extension</status>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb<sourcefile>mod_headers.c</sourcefile>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb<identifier>headers_module</identifier>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb<compatibility><directive module="mod_headers">RequestHeader</directive>

8a3a703eae0e35f674b189181609545c6fc77a09rbbis available only in Apache 2.0</compatibility>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb<summary>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb <p>This module provides directives to control and modify HTTP

8a3a703eae0e35f674b189181609545c6fc77a09rbb request and response headers. Headers can be merged, replaced

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb or removed.</p>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb</summary>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb

8a3a703eae0e35f674b189181609545c6fc77a09rbb<section id="order"><title>Order of Processing</title>

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb <p>The directives provided by <module>mod_headers</module> can

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb occur almost anywhere within the server configuration, and can be

8a3a703eae0e35f674b189181609545c6fc77a09rbb limited in scope by enclosing them in <a

05b7ad99e5d197b06c761fef0e06a44e353cbc54rbb href="/sections.html">configuration sections</a>.</p>

cee52fb06eb61191ce5d495abda58a75a9bb1c4fcoar

cee52fb06eb61191ce5d495abda58a75a9bb1c4fcoar <p>Order of processing is important and is affected both by the

cee52fb06eb61191ce5d495abda58a75a9bb1c4fcoar order in the configuration file and by placement in <a

cee52fb06eb61191ce5d495abda58a75a9bb1c4fcoar href="/sections.html#mergin">configuration sections</a>. These

bb7f455a6c49400b3dfcb3dfb84f9c3a32947a08rbb two headers have a different effect if reversed:</p>

bb7f455a6c49400b3dfcb3dfb84f9c3a32947a08rbb

bb7f455a6c49400b3dfcb3dfb84f9c3a32947a08rbb <example>

bb7f455a6c49400b3dfcb3dfb84f9c3a32947a08rbb RequestHeader append MirrorID "mirror 12"<br />

RequestHeader unset MirrorID

</example>

<p>This way round, the <code>MirrorID</code> header is not set. If

reversed, the MirrorID header is set to "mirror 12".</p>

</section>

<section id="examples"><title>Examples</title>

<ol>

<li>

Copy all request headers that begin with "TS" to the

response headers:

<example>

Header echo ^TS

</example>

</li>

<li>

Add a header, <code>MyHeader</code>, to the response including a

timestamp for when the request was received and how long it

took to begin serving the request. This header can be used by

the client to intuit load on the server or in isolating

bottlenecks between the client and the server.

<example>

Header add MyHeader "%D %t"

</example>

<p>results in this header being added to the response:</p>

<example>

MyHeader: D=3775428 t=991424704447256

</example>

</li>

<li>

Say hello to Joe

<example>

Header add MyHeader "Hello Joe. It took %D microseconds \<br />

for Apache to serve this request."

</example>

<p>results in this header being added to the response:</p>

<example>

MyHeader: Hello Joe. It took D=3775428 microseconds for Apache

to serve this request.

</example>

</li>

<li>

Conditionally send <code>MyHeader</code> on the response if and

only if header "MyRequestHeader" is present on the request. This

is useful for constructing headers in response to some client

stimulus. Note that this example requires the services of the

<module>mod_setenvif</module> module.

<example>

SetEnvIf MyRequestHeader value HAVE_MyRequestHeader<br />

Header add MyHeader "%D %t mytext" env=HAVE_MyRequestHeader<br />

</example>

<p>If the header <code>MyRequestHeader: value</code> is present on

the HTTP request, the response will contain the following header:</p>

<example>

MyHeader: D=3775428 t=991424704447256 mytext

</example>

</li>

</ol>

</section>

<directivesynopsis>

<name>RequestHeader</name>

<description>Configure HTTP request headers</description>

<syntax>RequestHeader set|append|add|unset <var>header</var>

[<var>value</var>] [env=[!]<var>variable</var>]</syntax>

<contextlist><context>server config</context><context>virtual host</context>

<context>directory</context><context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>This directive can replace, merge or remove HTTP request

headers. The header is modified just before the content handler

is run, allowing incoming headers to be modified. The action it

performs is determined by the first argument. This can be one

of the following values:</p>

<dl>

<dt><code>set</code></dt>

<dd>The request header is set, replacing any previous header

with this name</dd>

<dt><code>append</code></dt>

<dd>The request header is appended to any existing header of the

same name. When a new value is merged onto an existing header

it is separated from the existing header with a comma. This

is the HTTP standard way of giving a header multiple

values.</dd>

<dt><code>add</code></dt>

<dd>The request header is added to the existing set of headers,

even if this header already exists. This can result in two

(or more) headers having the same name. This can lead to

unforeseen consequences, and in general <code>append</code> should be

used instead.</dd>

<dt><code>unset</code></dt>

<dd>The request header of this name is removed, if it exists. If

there are multiple headers of the same name, all will be removed.

<var>value</var> must be omitted.</dd>

</dl>

<p>This argument is followed by a header name, which can

include the final colon, but it is not required. Case is

ignored. For <code>add</code>, <code>append</code> and

<code>set</code> a <var>value</var> is given as the third argument. If

<var>value</var> contains spaces, it should be surrounded by double

quotes. For unset, no <var>value</var> should be given.

<var>value</var> may be a character string, a string containing format

specifiers or a combination of both. The supported format specifiers

are the same as for the <directive module="mod_headers">Header</directive>,

please have a look there for details.</p>

<p>The <directive>RequestHeader</directive> directive may be followed by

an additional argument, which may be used to specify conditions under

which the action will be taken. If the <a href="/env.html">environment

variable</a> specified in the <code>env=<var>...</var></code> argument

exists (or if the environment variable does not exist and

<code>env=!<var>...</var></code> is specified) then the action specified

by the <directive>RequestHeader</directive> directive will take effect.

Otherwise, the directive will have no effect on the request.</p>

<p>The <directive>RequestHeader</directive> directive is processed

just before the request is run by its handler in the fixup phase.

This should allow headers generated by the browser, or by Apache

input filters to be overridden or modified.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>Header</name>

<description>Configure HTTP response headers</description>

<syntax>Header [<var>condition</var>] set|append|add|unset|echo

<var>header</var> [<var>value</var>] [env=[!]<var>variable</var>]</syntax>

<contextlist><context>server config</context><context>virtual host</context>

<context>directory</context><context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>This directive can replace, merge or remove HTTP response

headers. The header is modified just after the content handler

and output filters are run, allowing outgoing headers to be

modified.</p>

<p>The optional <var>condition</var> can be either <code>onsuccess</code>

or <code>always</code>. It determines, when the specified action should be

taken. <code>onsuccess</code> stands for <code>2<var>xx</var></code> status

codes and <code>always</code> for all status codes (including

<code>2<var>xx</var></code>).</p>

<p>The action it performs is determined by the second

argument. This can be one of the following values:</p>

<dl>

<dt><code>set</code></dt>

<dd>The response header is set, replacing any previous header

with this name. The <var>value</var> may be a format string.</dd>

<dt><code>append</code></dt>

<dd>The response header is appended to any existing header of

the same name. When a new value is merged onto an existing

header it is separated from the existing header with a comma.

This is the HTTP standard way of giving a header multiple values.</dd>

<dt><code>add</code></dt>

<dd>The response header is added to the existing set of headers,

even if this header already exists. This can result in two

(or more) headers having the same name. This can lead to

unforeseen consequences, and in general "append" should be

used instead.</dd>

<dt><code>unset</code></dt>

<dd>The response header of this name is removed, if it exists.

If there are multiple headers of the same name, all will be

removed. <var>value</var> must be omitted.</dd>

<dt><code>echo</code></dt>

<dd>Request headers with this name are echoed back in the

response headers. <var>header</var> may be a regular expression.

<var>value</var> must be omitted.</dd>

</dl>

<p>This argument is followed by a <var>header</var> name, which

can include the final colon, but it is not required. Case is

ignored for <code>set</code>, <code>append</code>, <code>add</code>

and <code>unset</code>. The <var>header</var> name for <code>echo</code>

is case sensitive and may be a regular expression.</p>

<p>For <code>add</code>, <code>append</code> and <code>set</code> a

<var>value</var> is specified as the third argument. If <var>value</var>

contains spaces, it should be surrounded by doublequotes.

<var>value</var> may be a character string, a string containing format

specifiers or a combination of both. The following format specifiers

are supported in <var>value</var>:</p>

<table border="1" style="zebra">

<columnspec><column width=".25"/><column width=".75"/></columnspec>

<tr><th>Format</th><th>Description</th></tr>

<tr><td><code>%%</code></td>

<td>The percent sign</td></tr>

<tr><td><code>%t</code></td>

<td>The time the request was received in Universal Coordinated Time

since the epoch (Jan. 1, 1970) measured in microseconds. The value

is preceded by <code>t=</code>.</td></tr>

<tr><td><code>%D</code></td>

<td>The time from when the request was received to the time the

headers are sent on the wire. This is a measure of the duration

of the request. The value is preceded by <code>D=</code>.</td></tr>

<tr><td><code>%{FOOBAR}e</code></td>

<td>The contents of the <a href="/env.html">environment

variable</a> <code>FOOBAR</code>.</td></tr>

<tr><td><code>%{FOOBAR}s</code></td>

<td>The contents of the <a href="mod_ssl.html#envvars">SSL environment

variable</a> <code>FOOBAR</code>, if <module>mod_ssl</module> is enabled.</td></tr>

</table>

<note><title>Note</title>

<p>The <code>%s</code> format specifier is only available in

Apache 2.1 and later; it can be used instead of <code>%e</code>

to avoid the overhead of enabling <code>SSLOptions

+StdEnvVars</code>. If <code>SSLOptions +StdEnvVars</code> must

be enabled anyway for some other reason, <code>%e</code> will be

more efficient than <code>%s</code>.</p>

</note>

<p>The <directive>Header</directive> directive may be followed by an

additional argument, which may be used to specify conditions

under which the action will be taken. If the <a

href="/env.html">environment variable</a> specified in the

<code>env=<var>...</var></code> argument exists (or if the environment

variable does not exist and <code>env=!<var>...</var></code> is specified)

then the action specified by the <directive>Header</directive> directive

will take effect. Otherwise, the directive will have no effect

on the request.</p>

<p>The <directive>Header</directive> directives are processed just

before the response is sent to the network. These means that it is

possible to set and/or override most headers, except for those headers

added by the header filter.</p>

</usage>

</directivesynopsis>

</modulesynopsis>