<title>Expressions in Apache HTTP Server</title>
<summary>
- <p>Historically, there are several syntax variants for expressions used to express
- a condition in the different modules of the Apache HTTP Server.
- There is some ongoing effort to only use a single variant, called <em>ap_expr</em>,
- for all configuration directives.
- This document describes the <em>ap_expr</em> expression parser.
+ <p>Historically, there are several syntax variants for expressions
+ used to express a condition in the different modules of the Apache
+ HTTP Server. There is some ongoing effort to only use a single
+ variant, called <em>ap_expr</em>, for all configuration directives.
+ This document describes the <em>ap_expr</em> expression parser.
</p>
+ <p>The <em>ap_expr</em> expression is intended to replace most other
+ expression variants in HTTPD. For example, the deprecated <directive
+ module="mod_ssl">SSLRequire</directive> expressions can be replaced
+ by <a href="mod/mod_authz_core.html#reqexpr">Require expr</a>. </p>
</summary>
+<seealso><directive module="core" type="section">If</directive></seealso>
+<seealso><directive module="core" type="section">ElseIf</directive></seealso>
+<seealso><directive module="core" type="section">Else</directive></seealso>
+<seealso><directive module="core">ErrorDocument</directive></seealso>
+<seealso><directive module="mod_alias">Alias</directive></seealso>
+<seealso><directive module="mod_alias">ScriptAlias</directive></seealso>
+<seealso><directive module="mod_alias">Redirect</directive></seealso>
+<seealso><directive module="mod_auth_basic">AuthBasicFake</directive></seealso>
+<seealso><directive module="mod_auth_form">AuthFormLoginRequiredLocation</directive></seealso>
+<seealso><directive module="mod_auth_form">AuthFormLoginSuccessLocation</directive></seealso>
+<seealso><directive module="mod_auth_form">AuthFormLogoutLocation</directive></seealso>
+<seealso><directive module="mod_authn_core">AuthName</directive></seealso>
+<seealso><directive module="mod_authn_core">AuthType</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><directive module="mod_crypto">CryptoKey</directive></seealso>
+<seealso><directive module="mod_crypto">CryptoIV</directive></seealso>
+<seealso><a href="mod/mod_authz_core.html#reqexpr">Require expr</a></seealso>
+<seealso><a href="mod/mod_authnz_ldap.html#requser">Require ldap-user</a></seealso>
+<seealso><a href="mod/mod_authnz_ldap.html#reqgroup">Require ldap-group</a></seealso>
+<seealso><a href="mod/mod_authnz_ldap.html#reqdn">Require ldap-dn</a></seealso>
+<seealso><a href="mod/mod_authnz_ldap.html#reqattribute">Require ldap-attribute</a></seealso>
+<seealso><a href="mod/mod_authnz_ldap.html#reqfilter">Require ldap-filter</a></seealso>
+<seealso><a href="mod/mod_authnz_ldap.html#reqsearch">Require ldap-search</a></seealso>
+<seealso><a href="mod/mod_authz_dbd.html#reqgroup">Require dbd-group</a></seealso>
+<seealso><a href="mod/mod_authz_dbm.html#reqgroup">Require dbm-group</a></seealso>
+<seealso><a href="mod/mod_authz_groupfile.html#reqgroup">Require group</a></seealso>
+<seealso><a href="mod/mod_authz_host.html#reqhost">Require host</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 BNF notation</title>
+ <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 point 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 point in
+ the BNF is <code>string</code>.
+ </p>
<blockquote>
<pre>
expr ::= "<strong>true</strong>" | "<strong>false</strong>"
rebackref ::= "<strong>$</strong>" [0-9]
-function ::= funcname "<strong>(</strong>" word "<strong>)</strong>"
+function ::= funcname "<strong>(</strong>" wordlist "<strong>)</strong>"
listfunction ::= listfuncname "<strong>(</strong>" word "<strong>)</strong>"
</pre>
<section id="vars">
<title>Variables</title>
-<p>XXX: not all vars are available in all request phases</p>
-
- <p>Request headers (XXX:see req function)</p>
+
+ <p>The expression parser provides a number of variables of the form
+ <code>%{HTTP_HOST}</code>. Note that the value of a variable may depend
+ on the phase of the request processing in which it is evaluated. For
+ example, an expression used in an <directive><If ></directive>
+ directive is evaluated before authentication is done. Therefore,
+ <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 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><th>Name</th></tr>
<tr><td><code>HTTP_ACCEPT</code></td></tr>
+ <tr><td><code>HTTP_COOKIE</code></td></tr>
<tr><td><code>HTTP_FORWARDED</code></td></tr>
<tr><td><code>HTTP_HOST</code></td></tr>
<tr><td><code>HTTP_PROXY_CONNECTION</code></td></tr>
<tr><th>Name</th><th>Description</th></tr>
<tr><td><code>REQUEST_METHOD</code></td>
- <td></td></tr>
+ <td>The HTTP method of the incoming request (e.g.
+ <code>GET</code>)</td></tr>
<tr><td><code>REQUEST_SCHEME</code></td>
- <td></td></tr>
+ <td>The scheme part of the request's URI</td></tr>
<tr><td><code>REQUEST_URI</code></td>
- <td></td></tr>
+ <td>The path part of the request's URI</td></tr>
+ <tr><td><code>DOCUMENT_URI</code></td>
+ <td>Same as <code>REQUEST_URI</code></td></tr>
<tr><td><code>REQUEST_FILENAME</code></td>
- <td></td></tr>
+ <td>The full local filesystem path to the file or script matching the
+ request, if this has already been determined by the server at the
+ time <code>REQUEST_FILENAME</code> is referenced. Otherwise, such
+ as when used in virtual host context, the same value as
+ <code>REQUEST_URI</code> </td></tr>
+ <tr><td><code>SCRIPT_FILENAME</code></td>
+ <td>Same as <code>REQUEST_FILENAME</code></td></tr>
+ <tr><td><code>LAST_MODIFIED</code></td>
+ <td>The date and time of last modification of the file in the format
+ <code>20101231235959</code>, if this has already been determined by
+ the server at the time <code>LAST_MODIFIED</code> is referenced.
+ </td></tr>
+ <tr><td><code>SCRIPT_USER</code></td>
+ <td>The user name of the owner of the script.</td></tr>
+ <tr><td><code>SCRIPT_GROUP</code></td>
+ <td>The group name of the group of the script.</td></tr>
+ <tr><td><code>PATH_INFO</code></td>
+ <td>The trailing path name information, see
+ <directive module="core">AcceptPathInfo</directive></td></tr>
+ <tr><td><code>QUERY_STRING</code></td>
+ <td>The query string of the current request</td></tr>
+ <tr><td><code>IS_SUBREQ</code></td>
+ <td>"<code>true</code>" if the current request is a subrequest,
+ "<code>false</code>" otherwise</td></tr>
+ <tr><td><code>THE_REQUEST</code></td>
+ <td>The complete request line (e.g.,
+ "<code>GET /index.html HTTP/1.1</code>")</td></tr>
+ <tr><td><code>REMOTE_ADDR</code></td>
+ <td>The IP address of the remote host</td></tr>
<tr><td><code>REMOTE_HOST</code></td>
- <td></td></tr>
- <tr><td><code>REMOTE_IDENT</code></td>
- <td></td></tr>
+ <td>The host name of the remote host</td></tr>
<tr><td><code>REMOTE_USER</code></td>
- <td></td></tr>
- <tr><td><code>SERVER_ADMIN</code></td>
- <td></td></tr>
+ <td>The name of the authenticated user, if any (not available during <directive><If></directive>)</td></tr>
+ <tr><td><code>REMOTE_IDENT</code></td>
+ <td>The user name set by <module>mod_ident</module></td></tr>
<tr><td><code>SERVER_NAME</code></td>
- <td></td></tr>
+ <td>The <directive module="core">ServerName</directive> of
+ the current vhost</td></tr>
<tr><td><code>SERVER_PORT</code></td>
- <td></td></tr>
+ <td>The server port of the current vhost, see
+ <directive module="core">ServerName</directive></td></tr>
+ <tr><td><code>SERVER_ADMIN</code></td>
+ <td>The <directive module="core">ServerAdmin</directive> of
+ the current vhost</td></tr>
<tr><td><code>SERVER_PROTOCOL</code></td>
- <td></td></tr>
- <tr><td><code>SCRIPT_FILENAME</code></td>
- <td></td></tr>
- <tr><td><code>PATH_INFO</code></td>
- <td></td></tr>
- <tr><td><code>QUERY_STRING</code></td>
- <td></td></tr>
- <tr><td><code>IS_SUBREQ</code></td>
- <td></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></td></tr>
+ <td>The <directive module="core">DocumentRoot</directive> of
+ the current vhost</td></tr>
<tr><td><code>AUTH_TYPE</code></td>
- <td></td></tr>
- <tr><td><code>THE_REQUEST</code></td>
- <td></td></tr>
+ <td>The configured <directive
+ module="mod_authn_core">AuthType</directive> (e.g.
+ "<code>basic</code>")</td></tr>
<tr><td><code>CONTENT_TYPE</code></td>
- <td></td></tr>
+ <td>The content type of the response (not available during <directive><If></directive>)</td></tr>
<tr><td><code>HANDLER</code></td>
- <td></td></tr>
- <tr><td><code>REMOTE_ADDR</code></td>
- <td></td></tr>
+ <td>The name of the <a href="handler.html">handler</a> creating
+ the response</td></tr>
+ <tr><td><code>HTTP2</code></td>
+ <td>"<code>on</code>" if the request uses http/2,
+ "<code>off</code>" otherwise</td></tr>
<tr><td><code>HTTPS</code></td>
- <td></td></tr>
+ <td>"<code>on</code>" if the request uses https,
+ "<code>off</code>" otherwise</td></tr>
<tr><td><code>IPV6</code></td>
- <td></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 (not available during <directive><If></directive>)</td></tr>
<tr><td><code>REQUEST_LOG_ID</code></td>
- <td></td></tr>
+ <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>
+ <tr><td><code>CONTEXT_PREFIX</code></td>
+ <td></td></tr>
+ <tr><td><code>CONTEXT_DOCUMENT_ROOT</code></td>
<td></td></tr>
</table>
<tr><th>Name</th><th>Description</th></tr>
<tr><td><code>TIME_YEAR</code></td>
- <td></td></tr>
+ <td>The current year (e.g. <code>2010</code>)</td></tr>
<tr><td><code>TIME_MON</code></td>
- <td></td></tr>
+ <td>The current month (<code>01</code>, ..., <code>12</code>)</td></tr>
<tr><td><code>TIME_DAY</code></td>
- <td></td></tr>
+ <td>The current day of the month (<code>01</code>, ...)</td></tr>
<tr><td><code>TIME_HOUR</code></td>
- <td></td></tr>
+ <td>The hour part of the current time
+ (<code>00</code>, ..., <code>23</code>)</td></tr>
<tr><td><code>TIME_MIN</code></td>
- <td></td></tr>
+ <td>The minute part of the current time </td></tr>
<tr><td><code>TIME_SEC</code></td>
- <td></td></tr>
+ <td>The second part of the current time </td></tr>
<tr><td><code>TIME_WDAY</code></td>
- <td></td></tr>
+ <td>The day of the week (starting with <code>0</code>
+ for Sunday)</td></tr>
<tr><td><code>TIME</code></td>
- <td></td></tr>
+ <td>The date and time in the format
+ <code>20101231235959</code></td></tr>
<tr><td><code>SERVER_SOFTWARE</code></td>
- <td></td></tr>
+ <td>The server version string</td></tr>
<tr><td><code>API_VERSION</code></td>
- <td></td></tr>
+ <td>The date of the API version (module magic number)</td></tr>
</table>
+ <p>Some modules register additional variables, see e.g.
+ <module>mod_ssl</module>.</p>
+
</section>
<section id="binop">
minus and at least two characters. The name is not case sensitive.
Modules may register additional binary operators.</p>
+ <section id="comp">
+ <title>Comparison operators</title>
+
<table border="1" style="zebra">
<columnspec><column width=".2"/><column width=".2"/><column width=".6"/></columnspec>
<tr><td><code>>=</code></td>
<td></td>
<td>String greater than or equal</td></tr>
+ <tr><td><code>=~</code></td>
+ <td></td>
+ <td>String matches the regular expression</td></tr>
+ <tr><td><code>!~</code></td>
+ <td></td>
+ <td>String does not match the regular expression</td></tr>
<tr><td><code>-eq</code></td>
<td><code>eq</code></td>
<td>Integer equality</td></tr>
<td><code>ge</code></td>
<td>Integer greater than or equal</td></tr>
</table>
+ </section>
+
+ <section id="binaryother">
+ <title>Other binary operators</title>
+
+ <table border="1" style="zebra">
+ <columnspec><column width=".2"/><column width=".8"/></columnspec>
+
+ <tr><th>Name</th><th>Description</th></tr>
+ <tr><td><code>-ipmatch</code></td>
+ <td>IP address matches address/netmask</td></tr>
+ <tr><td><code>-strmatch</code></td>
+ <td>left string matches pattern given by right string (containing
+ wildcards *, ?, [])</td></tr>
+ <tr><td><code>-strcmatch</code></td>
+ <td>same as <code>-strmatch</code>, but case insensitive</td></tr>
+ <tr><td><code>-fnmatch</code></td>
+ <td>same as <code>-strmatch</code>, but slashes are not matched by
+ wildcards</td></tr>
+ </table>
+ </section>
</section>
<section id="unnop">
<title>Unary operators</title>
- <p>Unary operators have the form "<code>-[a-zA-Z]</code>", i.e. a
- minus and one character. The name <em>is</em> case sensitive.
+ <p>Unary operators take one argument and have the form
+ "<code>-[a-zA-Z]</code>", i.e. a minus and one character.
+ The name <em>is</em> case sensitive.
Modules may register additional unary operators.</p>
<table border="1" style="zebra">
<columnspec><column width=".2"/><column width=".2"/><column width=".6"/></columnspec>
- <tr><th>Name</th><th>Description</th></tr>
+ <tr><th>Name</th><th>Description</th><th>Restricted</th></tr>
+ <tr><td><code>-d</code></td>
+ <td>The argument is treated as a filename.
+ True if the file exists and is a directory</td><td>yes</td></tr>
+ <tr><td><code>-e</code></td>
+ <td>The argument is treated as a filename.
+ True if the file (or dir or special) exists</td><td>yes</td></tr>
+ <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><td><code>-h</code></td>
+ <td>The argument is treated as a filename.
+ True if the file exists and is symlink
+ (same as <code>-L</code>)</td><td>yes</td></tr>
+ <tr><td><code>-F</code></td>
+ <td>True if string is a valid file, accessible via all the server's
+ currently-configured access controls for that path. This uses an
+ internal subrequest to do the check, so use it with care - it can
+ impact your server's performance!</td><td></td></tr>
+ <tr><td><code>-U</code></td>
+ <td>True if string is a valid URL, accessible via all the server's
+ currently-configured access controls for that path. This uses an
+ internal subrequest to do the check, so use it with care - it can
+ impact your server's performance!</td><td></td></tr>
+ <tr><td><code>-A</code></td>
+ <td>Alias for <code>-U</code></td><td></td></tr>
<tr><td><code>-n</code></td>
- <td>String is not empty</td></tr>
+ <td>True if string is not empty</td><td></td></tr>
<tr><td><code>-z</code></td>
- <td>String is empty</td></tr>
+ <td>True if string is empty</td><td></td></tr>
+ <tr><td><code>-T</code></td>
+ <td>False if string is empty, "<code>0</code>", "<code>off</code>",
+ "<code>false</code>", or "<code>no</code>" (case insensitive).
+ True otherwise.</td><td></td></tr>
+ <tr><td><code>-R</code></td>
+ <td>Same as "<code>%{REMOTE_ADDR} -ipmatch ...</code>", but more
+ efficient
+ </td><td></td></tr>
</table>
+ <p>The operators marked as "restricted" are not available in some modules
+ like <module>mod_include</module>.</p>
</section>
<section id="functions">
Modules may register additional functions.</p>
<table border="1" style="zebra">
- <columnspec><column width=".2"/><column width=".8"/></columnspec>
+ <columnspec><column width=".2"/><column width=".4"/><column width=".4"/></columnspec>
- <tr><th>Name</th><th>Description</th></tr>
+ <tr><th>Name</th><th>Description</th><th>Special notes</th></tr>
<tr><td><code>req</code>, <code>http</code></td>
- <td>Get HTTP request header</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></tr>
+ <td>Get HTTP response header (most response headers will not yet be set
+ during <directive><If></directive>)</td><td></td></tr>
<tr><td><code>reqenv</code></td>
- <td>Lookup request environment variable</td></tr>
+ <td>Lookup request environment variable (as a shortcut,
+ <code>v</code> can also be used to access variables).
+ </td>
+ <td>ordering</td></tr>
<tr><td><code>osenv</code></td>
- <td>Lookup operating system environment variable</td></tr>
+ <td>Lookup operating system environment variable</td><td></td></tr>
<tr><td><code>note</code></td>
- <td>Lookup request environment variable</td></tr>
+ <td>Lookup request note</td><td>ordering</td></tr>
<tr><td><code>env</code></td>
<td>Return first match of <code>note</code>, <code>reqenv</code>,
- <code>osenv</code></td></tr>
+ <code>osenv</code></td><td>ordering</td></tr>
<tr><td><code>tolower</code></td>
- <td>Convert string to lower case</td></tr>
+ <td>Convert string to lower case</td><td></td></tr>
<tr><td><code>toupper</code></td>
- <td>Convert string to uppser case</td></tr>
+ <td>Convert string to upper case</td><td></td></tr>
<tr><td><code>escape</code></td>
- <td>Escape special characters in %hex encoding</td></tr>
+ <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></tr>
+ <td>Unescape %hex encoded string, leaving encoded slashes alone;
+ return empty string if %00 is found</td><td></td></tr>
+ <tr><td><code>base64</code></td>
+ <td>Encode the string using base64 encoding</td><td></td></tr>
+ <tr><td><code>unbase64</code></td>
+ <td>Decode base64 encoded string, return truncated string if 0x00 is
+ found</td><td></td></tr>
+ <tr><td><code>md5</code></td>
+ <td>Hash the string using MD5, then encode the hash with hexadecimal
+ encoding</td><td></td></tr>
+ <tr><td><code>sha1</code></td>
+ <td>Hash the string using SHA1, then encode the hash with hexadecimal
+ encoding</td><td></td></tr>
<tr><td><code>file</code></td>
- <td>Read contents from a file</td></tr>
+ <td>Read contents from a file (including line endings, when present)
+ </td><td>restricted</td></tr>
+ <tr><td><code>filemod</code></td>
+ <td>Return last modification time of a file (or 0 if file does not exist
+ or is not regular file)</td><td>restricted</td></tr>
+ <tr><td><code>filesize</code></td>
+ <td>Return size of a file (or 0 if file does not exist or is not
+ regular file)</td><td>restricted</td></tr>
+ <tr><td><code>ldap</code></td>
+ <td>Escape characters as required by LDAP distinguished name escaping
+ (RFC4514) and LDAP filter escaping (RFC4515).</td><td></td></tr>
+ <tr><td><code>replace</code></td>
+ <td>replace(string, "from", "to") replaces all occurences of "from"
+ in the string with "to".</td><td></td></tr>
+
</table>
- <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.
- Functions names are not case sensitive.
- Modules may register additional functions.</p>
+ <p>The functions marked as "restricted" in the final column are not
+ available in some modules like <module>mod_include</module>.</p>
+
+ <p>The functions marked as "ordering" in the final column require some
+ consideration for the ordering of different components of the server,
+ especially when the function is used within the
+ <<directive module="core">If</directive>> directive which is
+ evaluated relatively early.</p>
+ <note>
+ <title>Environment variable ordering</title>
+ When environment variables are looked up within an
+ <<directive module="core">If</directive>> condition, it's important
+ to consider how extremely early in request processing that this
+ resolution occurs. As a guideline, any directive defined outside of virtual host
+ context (directory, location, htaccess) is not likely to have yet had a
+ chance to execute. <directive module="mod_setenvif">SetEnvIf</directive>
+ in virtual host scope is one directive that runs prior to this resolution
+ <br/>
+ <br/>
+ When <code>reqenv</code> is used outside of <<directive module="core"
+ >If</directive>>, the resolution will generally occur later, but the
+ exact timing depends on the directive the expression has been used within.
+ </note>
+
+ <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. Functions names are not case
+ sensitive. Modules may register additional functions.</p>
<p>There are no built-in list-valued functions. <module>mod_ssl</module>
provides <code>PeerExtList</code>. See the description of
</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>
+
+# Check a HTTP header for a list of values
+<If "%{HTTP:X-example-header} in { 'foo', 'bar', 'baz' }">
+ Header set matched true
+</If>
+
+# Check an environment variable for a regular expression, negated.
+<If "! reqenv('REDIRECT_FOO') =~ /bar/">
+ Header set matched true
+</If>
+
+# Check result of URI mapping by running in Directory context with -f
+<Directory "/var/www">
+ AddEncoding x-gzip gz
+<If "-f '%{REQUEST_FILENAME}.unzipme' && ! %{HTTP:Accept-Encoding} =~ /gzip/">
+ SetOutputFilter INFLATE
+</If>
+</Directory>
+
+# Check against the client IP
+<If "-R '192.168.1.0/24'">
+ Header set matched true
+</If>
+
+# Function examples in boolean context
+<If "md5('foo') == 'acbd18db4cc2f85cedef654fccc4a4d8'">
+ Header set checksum-matched true
+</If>
+<If "md5('foo') == replace('md5:XXXd18db4cc2f85cedef654fccc4a4d8', 'md5:XXX', 'acb')">
+ Header set checksum-matched-2 true
+</If>
+
+# Function example in string context
+Header set foo-checksum "expr=%{md5:foo}"
+
+# This delays the evaluation of the condition clause compared to <If>
+Header always set CustomHeader my-value "expr=%{REQUEST_URI} =~ m#^/special_path\.php$#"
+
+ </highlight>
+</section>
+
<section id="other">
<title>Other</title>
<tr><th>Name</th><th>Alternative</th> <th>Description</th></tr>
<tr><td><code>-in</code></td>
<td><code>in</code></td>
- <td>string contained in string list</td></tr>
+ <td>string contained in wordlist</td></tr>
<tr><td><code>/regexp/</code></td>
<td><code>m#regexp#</code></td>
- <td>Regular expression (the second form allows different delimiters than /)</td></tr>
+ <td>Regular expression (the second form allows different
+ delimiters than /)</td></tr>
<tr><td><code>/regexp/i</code></td>
<td><code>m#regexp#i</code></td>
<td>Case insensitive regular expression</td></tr>
<section id="rebackref">
<title>Regular expression backreferences</title>
<p>The strings <code>$0</code> ... <code>$9</code> allow to reference
- the capture groups form a previously executed, successfully
+ the capture groups from a previously executed, successfully
matching regular expressions. They can normally only be used in the
same expression as the matching regex, but some modules allow special
uses.</p>
</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>
+
+<section id="compatibility">
+ <title>Version History</title>
+ <p>The <code>req_novary</code> <a href="#functions">function</a>
+ is available for versions 2.4.4 and later.</p>
+ <p>The <code>SERVER_PROTOCOL_VERSION</code>,
+ <code>SERVER_PROTOCOL_VERSION_MAJOR</code> and
+ <code>SERVER_PROTOCOL_VERSION_MINOR</code>
+ <a href="#vars">variables</a>
+ are available for versions 2.5.0 and later.</p>
+</section>
+
</manualpage>
projects / apache / blobdiff