<seealso><directive module="core" type="section">Else</directive></seealso>
<seealso><directive module="mod_rewrite">RewriteCond</directive></seealso>
<seealso><directive module="mod_setenvif">SetEnvIfExpr</directive></seealso>
+<seealso><directive module="mod_headers">Header</directive></seealso>
+<seealso><directive module="mod_headers">RequestHeader</directive></seealso>
<seealso><directive module="mod_filter">FilterProvider</directive></seealso>
<seealso><a href="mod/mod_authz_core.html#reqexpr">Require expr</a></seealso>
<seealso><directive module="mod_ssl">SSLRequire</directive></seealso>
+<seealso><directive module="mod_log_debug">LogMessage</directive></seealso>
<seealso><module>mod_include</module></seealso>
<section id="grammar">
- <title>Grammar in Backus–Naur Form notation</title>
- <p><a href="http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form">Backus–Naur Form</a> (BNF) is a notation
+ <title>Grammar in Backus-Naur Form notation</title>
+ <p><a href="http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form">Backus-Naur Form</a> (BNF) is a notation
technique for context-free grammars, often used to describe the syntax of languages used in computing.
+ In most cases, expressions are used to express boolean values.
+ For these, the starting boint in the BNF is <code>expr</code>. However, a few directives
+ like <directive module="mod_log_debug">LogMessage</directive> accept expressions
+ that evaluate to a string value. For those, the starting boint in the BNF is <code>string</code>.
</p>
<blockquote>
<pre>
<code>%{REMOTE_USER}</code> will not be set in this case.</p>
<p>The following variables provide the values of the named HTTP request
- headers. The values of other headers can be obtained witht the
- <code>req</code> <a href="#functions">function</a>.</p>
+ headers. The values of other headers can be obtained with the
+ <code>req</code> <a href="#functions">function</a>. Using these
+ variables may cause the header name to be added to the Vary
+ header of the HTTP response, except where otherwise noted for the
+ directive accepting the expression. The <code>req_novary</code>
+ <a href="#functions">function</a> may be used to circumvent this
+ behavior.</p>
<table border="1" style="zebra">
<columnspec><column width="1"/></columnspec>
<tr><td><code>REQUEST_SCHEME</code></td>
<td>The scheme part of the request's URI</td></tr>
<tr><td><code>REQUEST_URI</code></td>
- <td>The URI of the request</td></tr>
+ <td>The path part of the request's URI</td></tr>
<tr><td><code>DOCUMENT_URI</code></td>
<td>Same as REQUEST_URI</td></tr>
<tr><td><code>REQUEST_FILENAME</code></td>
<td>The <directive module="core">ServerAdmin</directive> of
the current vhost</td></tr>
<tr><td><code>SERVER_PROTOCOL</code></td>
- <td>The protocol used by the request</td></tr>
+ <td>The protocol used by the request (e.g. HTTP/1.1). In some types of
+ internal subrequests, this variable has the value
+ <code>INCLUDED</code>.</td></tr>
+ <tr><td><code>SERVER_PROTOCOL_VERSION</code></td>
+ <td>A number that encodes the HTTP version of the request:
+ <code>1000 * major + minor</code>. For example, <code>1001</code>
+ corresponds to HTTP/1.1 and <code>9</code> corresponds
+ to HTTP/0.9</td></tr>
+ <tr><td><code>SERVER_PROTOCOL_VERSION_MAJOR</code></td>
+ <td>The major version part of the HTTP version of the request,
+ e.g. <code>1</code> for HTTP/1.0</td></tr>
+ <tr><td><code>SERVER_PROTOCOL_VERSION_MINOR</code></td>
+ <td>The minor version part of the HTTP version of the request,
+ e.g. <code>0</code> for HTTP/1.0</td></tr>
<tr><td><code>DOCUMENT_ROOT</code></td>
<td>The <directive module="core">DocumentRoot</directive> of
the current vhost</td></tr>
<td>"<code>on</code>" if the connection uses IPv6,
"<code>off</code>" otherwise</td></tr>
<tr><td><code>REQUEST_STATUS</code></td>
- <td>The HTTP error status of the request<td></tr>
+ <td>The HTTP error status of the request</td></tr>
<tr><td><code>REQUEST_LOG_ID</code></td>
<td>The error log id of the request (see
<directive module="core">ErrorLogFormat</directive>)</td></tr>
<tr><td><code>CONN_LOG_ID</code></td>
<td>The error log id of the connection (see
<directive module="core">ErrorLogFormat</directive>)</td></tr>
+ <tr><td><code>CONN_REMOTE_ADDR</code></td>
+ <td>The peer IP address of the connection (see the
+ <module>mod_remoteip</module> module)</td></tr>
</table>
<tr><td><code>-f</code></td>
<td>The argument is treated as a filename.
True if the file exists and is regular file</td><td>yes</td></tr>
+ <tr><td><code>-s</code></td>
+ <td>The argument is treated as a filename.
+ True if the file exists and is not empty</td><td>yes</td></tr>
<tr><td><code>-L</code></td>
<td>The argument is treated as a filename.
True if the file exists and is symlink</td><td>yes</td></tr>
<tr><th>Name</th><th>Description</th><th>Restricted</th></tr>
<tr><td><code>req</code>, <code>http</code></td>
- <td>Get HTTP request header</td><td></td></tr>
+ <td>Get HTTP request header; header names may be added to the Vary
+ header, see below</td><td></td></tr>
+ <tr><td><code>req_novary</code></td>
+ <td>Same as <code>req</code>, but header names will not be added to the
+ Vary header</td><td></td></tr>
<tr><td><code>resp</code></td>
<td>Get HTTP response header</td><td></td></tr>
<tr><td><code>reqenv</code></td>
<tr><td><code>escape</code></td>
<td>Escape special characters in %hex encoding</td><td></td></tr>
<tr><td><code>unescape</code></td>
- <td>Unescape %hex encoded string, leaving URL-special characters
- encoded (XXX: describe better)</td><td></td></tr>
+ <td>Unescape %hex encoded string, leaving encoded slashes alone;
+ return empty string if %00 is found</td><td></td></tr>
<tr><td><code>file</code></td>
<td>Read contents from a file</td><td>yes</td></tr>
<tr><td><code>filesize</code></td>
<p>The functions marked as "restricted" are not available in some modules
like <module>mod_include</module>.</p>
+ <p>When the functions <code>req</code> or <code>http</code> are used,
+ the header name will automatically be added to the Vary header of the
+ HTTP response, except where otherwise noted for the directive accepting
+ the expression. The <code>req_novary</code> function can be used to
+ prevent names from being added to the Vary header.</p>
+
<p>In addition to string-valued functions, there are also list-valued functions which
take one string as argument and return a wordlist, i.e. a list of strings. The wordlist
can be used with the special <code>-in</code> operator.
</section>
+<section id="examples">
+
+ <title>Example expressions</title>
+ <p>The following examples show how expressions might be used to evaluate requests:</p>
+ <!-- This section should probably be extended with more, useful examples -->
+ <highlight language="config">
+# Compare the host name to example.com and redirect to www.example.com if it matches
+<If "%{HTTP_HOST} == 'example.com'">
+ Redirect permanent / http://www.example.com
+</If>
+
+# Force text/plain if requesting a file with the query string contains 'forcetext'
+<If "%{QUERY_STRING} =~ /forcetext/">
+ ForceType text/plain
+</If>
+
+# Only allow access to this content during business hours
+<Directory "/foo/bar/business">
+ Require expr %{TIME_HOUR} -gt 9 && %{TIME_HOUR} -lt 17
+</Directory>
+ </highlight>
+</section>
+
<section id="other">
<title>Other</title>
</section>
+<section id="sslrequire">
+ <title>Comparison with SSLRequire</title>
+ <p>The <em>ap_expr</em> syntax is mostly a superset of the syntax of the
+ deprecated <directive module="mod_ssl">SSLRequire</directive> directive.
+ The differences are described in <directive
+ module="mod_ssl">SSLRequire</directive>'s documentation.</p>
+</section>
+
</manualpage>
projects / apache / blobdiff