<modulesynopsis>
<name>mod_headers</name>
-<description>Customization of HTTP request
- and response headers</description>
+<description>Customization of HTTP request and response
+headers</description>
<status>Extension</status>
<sourcefile>mod_headers.c</sourcefile>
<identifier>headers_module</identifier>
-<compatibility>RequestHeader is available only in Apache 2.0</compatibility>
+<compatibility><directive module="mod_headers">RequestHeader</directive>
+is available only in Apache 2.0</compatibility>
<summary>
<p>This module provides directives to control and modify HTTP
or removed.</p>
</summary>
-<section><title>Order of Processing</title>
+<section id="order"><title>Order of Processing</title>
- <p>The directives provided by mod_header can occur almost
- anywhere within the server configuration. They are valid in the
+ <p>The directives provided by <module>mod_headers</module> can occur
+ almost anywhere within the server configuration. They are valid in the
main server config and virtual host sections, inside
- <Directory>, <Location> and <Files> sections,
- and within .htaccess files.</p>
+ <directive module="core" type="section">Directory</directive>,
+ <directive module="core" type="section">Location</directive> and
+ <directive module="core" type="section">Files</directive> sections,
+ and within <code>.htaccess</code> files.</p>
<p>The directives are processed in the following order:</p>
<ol>
<li>main server</li>
-
<li>virtual host</li>
-
- <li><Directory> sections and .htaccess</li>
-
- <li><Location></li>
-
- <li><Files></li>
+ <li><directive type="section">Directory</directive> sections and
+ <code>.htaccess</code></li>
+ <li><directive type="section">Files</directive></li>
+ <li><directive type="section">Location</directive></li>
</ol>
<p>Order is important. These two headers have a different
effect if reversed:</p>
-<example>
-RequestHeader append MirrorID "mirror 12"<br />
- RequestHeader unset MirrorID
-</example>
+ <example>
+ RequestHeader append MirrorID "mirror 12"<br />
+ RequestHeader unset MirrorID
+ </example>
- <p>This way round, the MirrorID header is not set. If reversed,
- the MirrorID header is set to "mirror 12".</p>
+ <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><title>Example</title>
+<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, MyHeader, 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>
- results in this header being added to the response:
-<example>
- MyHeader: D=3775428 t=991424704447256
-</example>
+ <li>
+ Copy all request headers that begin with "TS" to the
+ response headers:
+
+ <example>
+ Header echo ^TS*
+ </example>
</li>
- <li>Say hello to Joe
+ <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>
-<example>
- Header add MyHeader "Hello Joe. It took %D microseconds for Apache to serve this request."
-</example>
- results in this header being added to the response:
-<example>
- MyHeader: Hello Joe. It took D=3775428 microseconds for Apache to serve this request.
-</example>
+ <p>results in this header being added to the response:</p>
+
+ <example>
+ MyHeader: D=3775428 t=991424704447256
+ </example>
</li>
- <li>Conditionally send MyHeader 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
- mod_setenvif module.
-
-<example>
- SetEnvIf MyRequestHeader value HAVE_MyRequestHeader<br />
- Header add MyHeader "%D %t mytext" env=HAVE_MyRequestHeader
-</example>
- If the header "MyRequestHeader: value" is present on the
- HTTP request, the response will contain the following
- header:
-<example>
- MyHeader: D=3775428 t=991424704447256 mytext
-</example>
+ <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 <em>header</em>
-[<em>value</em>]</syntax>
-<contextlist><context>server config</context>
-<context>virtual host</context>
-<context>directory</context>
-<context>.htaccess</context></contextlist>
+<syntax>RequestHeader set|append|add|unset <var>header</var>
+[<var>value</var>]</syntax>
+<contextlist><context>server config</context><context>virtual host</context>
+<context>directory</context><context>.htaccess</context></contextlist>
<override>FileInfo</override>
<usage>
performs is determined by the first argument. This can be one
of the following values:</p>
- <ul>
- <li><strong>set</strong><br />
- The request header is set, replacing any previous header
- with this name</li>
-
- <li><strong>append</strong><br />
- 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.</li>
-
- <li><strong>add</strong><br />
- 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 "append" should be
- used instead.</li>
-
- <li><strong>unset</strong><br />
- The request header of this name is removed, if it exists. If
- there are multiple headers of the same name, all will be
- removed.</li>
- </ul>
+ <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.</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 <em>value</em> is given as the third argument. If
- <em>value</em> contains spaces, it should be surrounded by double
- quotes. For unset, no <em>value</em> should be given.</p>
+ <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.</p>
<p>The <directive>RequestHeader</directive> directive is processed
just before the request is run by its handler in the fixup phase.
<directivesynopsis>
<name>Header</name>
<description>Configure HTTP response headers</description>
-<syntax>Header set|append|add|unset|echo <em>header</em>
-[<em>value</em>]</syntax>
-<contextlist><context>server config</context>
-<context>virtual host</context>
-<context>directory</context>
-<context>.htaccess</context></contextlist>
+<syntax>Header 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>
modified. The action it performs is determined by the first
argument. This can be one of the following values:</p>
- <ul>
- <li><strong>set</strong><br />
- The response header is set, replacing any previous header
- with this name. The <em>value</em> may be a format
- string.</li>
-
- <li><strong>append</strong><br />
- 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.</li>
-
- <li><strong>add</strong><br />
- 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.</li>
-
- <li><strong>unset</strong><br />
- The response header of this name is removed, if it exists.
- If there are multiple headers of the same name, all will be
- removed.</li>
-
- <li><strong>echo</strong><br />
- Request headers with this name are echoed back in the
- response headers. <em>header</em> may be a regular
- expression.</li>
- </ul>
-
- <p>This argument is followed by a <em>header</em> name, which
+ <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.</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.</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 set, append, add and unset. The <em>header</em>
- name for echo is case sensitive and may be a regular
- expression.</p>
-
- <p>For <code>add</code>, <code>append</code> and
- <code>set</code> a <em>value</em> is specified as the third
- argument. If <em>value</em> contains spaces, it should be
- surrounded by doublequotes. <em>value</em> may be a character
- string, a string containing format specifiers or a combination
- of both. The following format specifiers are supported in
- <em>value</em>:</p>
-<table>
-<tr><td>%t: </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 "t=".</td></tr>
-
-<tr><td>%D: </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 "D=".</td></tr>
-
-<tr><td>%{FOOBAR}e:</td> <td>The contents of the <a href="../env.html">environment
-variable</a> FOOBAR.</td></tr>
-</table>
+ 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">
+ <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>
+ </table>
<p>When the <directive>Header</directive> directive is used with the
<code>add</code>, <code>append</code>, or <code>set</code>
will take effect. Otherwise, the directive will have no effect
on the request.</p>
- <p>The Header 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>
+ <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>
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