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| <manualpage metafile="expr.xml.meta"> |
| |
| <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> |
| <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">If</directive></seealso> |
| <seealso><directive module="mod_rewrite">RewriteCond</directive></seealso> |
| <seealso><directive module="mod_setenvif">SetEnvIfExpr</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><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 |
| technique for context-free grammars, often used to describe the syntax of languages used in computing. |
| </p> |
| <blockquote> |
| <pre> |
| expr ::= "<strong>true</strong>" | "<strong>false</strong>" |
| | "<strong>!</strong>" expr |
| | expr "<strong>&&</strong>" expr |
| | expr "<strong>||</strong>" expr |
| | "<strong>(</strong>" expr "<strong>)</strong>" |
| | comp |
| |
| comp ::= stringcomp |
| | integercomp |
| | unaryop word |
| | word binaryop word |
| | word "<strong>in</strong>" "<strong>{</strong>" wordlist "<strong>}</strong>" |
| | word "<strong>in</strong>" listfunction |
| | word "<strong>=~</strong>" regex |
| | word "<strong>!~</strong>" regex |
| |
| |
| stringcomp ::= word "<strong>==</strong>" word |
| | word "<strong>!=</strong>" word |
| | word "<strong><</strong>" word |
| | word "<strong><=</strong>" word |
| | word "<strong>></strong>" word |
| | word "<strong>>=</strong>" word |
| |
| integercomp ::= word "<strong>-eq</strong>" word | word "<strong>eq</strong>" word |
| | word "<strong>-ne</strong>" word | word "<strong>ne</strong>" word |
| | word "<strong>-lt</strong>" word | word "<strong>lt</strong>" word |
| | word "<strong>-le</strong>" word | word "<strong>le</strong>" word |
| | word "<strong>-gt</strong>" word | word "<strong>gt</strong>" word |
| | word "<strong>-ge</strong>" word | word "<strong>ge</strong>" word |
| |
| wordlist ::= word |
| | wordlist "<strong>,</strong>" word |
| |
| word ::= word "<strong>.</strong>" word |
| | digit |
| | "<strong>'</strong>" string "<strong>'</strong>" |
| | "<strong>"</strong>" string "<strong>"</strong>" |
| | variable |
| | rebackref |
| | function |
| |
| string ::= stringpart |
| | string stringpart |
| |
| stringpart ::= cstring |
| | variable |
| | rebackref |
| |
| cstring ::= ... |
| digit ::= [0-9]+ |
| |
| variable ::= "<strong>%{</strong>" varname "<strong>}</strong>" |
| | "<strong>%{</strong>" funcname "<strong>:</strong>" funcargs "<strong>}</strong>" |
| |
| rebackref ::= "<strong>$</strong>" [0-9] |
| |
| function ::= funcname "<strong>(</strong>" word "<strong>)</strong>" |
| |
| listfunction ::= listfuncname "<strong>(</strong>" word "<strong>)</strong>" |
| </pre> |
| </blockquote> |
| |
| </section> |
| |
| <section id="vars"> |
| <title>Variables</title> |
| |
| <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 witht the |
| <code>req</code> <a href="#functions">function</a>.</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_FORWARDED</code></td></tr> |
| <tr><td><code>HTTP_HOST</code></td></tr> |
| <tr><td><code>HTTP_PROXY_CONNECTION</code></td></tr> |
| <tr><td><code>HTTP_REFERER</code></td></tr> |
| <tr><td><code>HTTP_USER_AGENT</code></td></tr> |
| |
| </table> |
| |
| <p>Other request related variables</p> |
| |
| <table border="1" style="zebra"> |
| <columnspec><column width=".4"/><column width=".6"/></columnspec> |
| |
| <tr><th>Name</th><th>Description</th></tr> |
| <tr><td><code>REQUEST_METHOD</code></td> |
| <td>The HTTP method of the incoming request (e.g. |
| <code>GET</code>)</td></tr> |
| <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> |
| <tr><td><code>REQUEST_FILENAME</code></td> |
| <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>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>The host name of the remote host</td></tr> |
| <tr><td><code>REMOTE_USER</code></td> |
| <td>The name of the authenticated user (if any)</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>The <directive module="core">ServerName</directive> of |
| the current vhost</td></tr> |
| <tr><td><code>SERVER_PORT</code></td> |
| <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>The protocol used by the request</td></tr> |
| <tr><td><code>DOCUMENT_ROOT</code></td> |
| <td>The <directive module="core">DocumentRoot</directive> of |
| the current vhost</td></tr> |
| <tr><td><code>AUTH_TYPE</code></td> |
| <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>The content type of the response</td></tr> |
| <tr><td><code>HANDLER</code></td> |
| <td>The name of the <a href="handler.html">handler</a> creating |
| the response</td></tr> |
| <tr><td><code>HTTPS</code></td> |
| <td>"<code>on</code>" if the request uses https, |
| "<code>off</code>" otherwise</td></tr> |
| <tr><td><code>IPV6</code></td> |
| <td>"<code>on</code>" if the connection uses IPv6, |
| "<code>off</code>" otherwise</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> |
| |
| </table> |
| |
| <p>Misc variables</p> |
| |
| <table border="1" style="zebra"> |
| <columnspec><column width=".4"/><column width=".6"/></columnspec> |
| |
| <tr><th>Name</th><th>Description</th></tr> |
| <tr><td><code>TIME_YEAR</code></td> |
| <td>The current year (e.g. <code>2010</code>)</td></tr> |
| <tr><td><code>TIME_MON</code></td> |
| <td>The current month (<code>1</code>, ..., <code>12</code>)</td></tr> |
| <tr><td><code>TIME_DAY</code></td> |
| <td>The current day of the month</td></tr> |
| <tr><td><code>TIME_HOUR</code></td> |
| <td>The hour part of the current time |
| (<code>0</code>, ..., <code>23</code>)</td></tr> |
| <tr><td><code>TIME_MIN</code></td> |
| <td>The minute part of the current time </td></tr> |
| <tr><td><code>TIME_SEC</code></td> |
| <td>The second part of the current time </td></tr> |
| <tr><td><code>TIME_WDAY</code></td> |
| <td>The day of the week (starting with <code>0</code> |
| for Sunday)</td></tr> |
| <tr><td><code>TIME</code></td> |
| <td>The date and time in the format <code>20101231235959</code></td></tr> |
| <tr><td><code>SERVER_SOFTWARE</code></td> |
| <td>The server version string</td></tr> |
| <tr><td><code>API_VERSION</code></td> |
| <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"> |
| <title>Binary operators</title> |
| |
| <p>With the exception of some built-in comparison operators, binary |
| operators have the form "<code>-[a-zA-Z][a-zA-Z0-9_]+</code>", i.e. a |
| 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><th>Name</th><th>Alternative</th> <th>Description</th></tr> |
| <tr><td><code>==</code></td> |
| <td><code>=</code></td> |
| <td>String equality</td></tr> |
| <tr><td><code>!=</code></td> |
| <td></td> |
| <td>String inequality</td></tr> |
| <tr><td><code><</code></td> |
| <td></td> |
| <td>String less than</td></tr> |
| <tr><td><code><=</code></td> |
| <td></td> |
| <td>String less than or equal</td></tr> |
| <tr><td><code>></code></td> |
| <td></td> |
| <td>String greater than</td></tr> |
| <tr><td><code>>=</code></td> |
| <td></td> |
| <td>String greater than or equal</td></tr> |
| <tr><td><code>-eq</code></td> |
| <td><code>eq</code></td> |
| <td>Integer equality</td></tr> |
| <tr><td><code>-ne</code></td> |
| <td><code>ne</code></td> |
| <td>Integer inequality</td></tr> |
| <tr><td><code>-lt</code></td> |
| <td><code>lt</code></td> |
| <td>Integer less than</td></tr> |
| <tr><td><code>-le</code></td> |
| <td><code>le</code></td> |
| <td>Integer less than or equal</td></tr> |
| <tr><td><code>-gt</code></td> |
| <td><code>gt</code></td> |
| <td>Integer greater than</td></tr> |
| <tr><td><code>-ge</code></td> |
| <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. |
| 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><td><code>-n</code></td> |
| <td>True if string is not empty</td></tr> |
| <tr><td><code>-z</code></td> |
| <td>True if string is empty</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></tr> |
| <tr><td><code>-R</code></td> |
| <td>Same as "<code>%{REMOTE_ADDR} -ipmatch ...</code>", but more efficient |
| </td></tr> |
| </table> |
| |
| </section> |
| |
| <section id="functions"> |
| <title>Functions</title> |
| |
| <p>Normal string-valued functions take one string as argument and return |
| a string. Functions names are not case sensitive. |
| Modules may register additional functions.</p> |
| |
| <table border="1" style="zebra"> |
| <columnspec><column width=".2"/><column width=".8"/></columnspec> |
| |
| <tr><th>Name</th><th>Description</th></tr> |
| <tr><td><code>req</code>, <code>http</code></td> |
| <td>Get HTTP request header</td></tr> |
| <tr><td><code>resp</code></td> |
| <td>Get HTTP response header</td></tr> |
| <tr><td><code>reqenv</code></td> |
| <td>Lookup request environment variable</td></tr> |
| <tr><td><code>osenv</code></td> |
| <td>Lookup operating system environment variable</td></tr> |
| <tr><td><code>note</code></td> |
| <td>Lookup request note</td></tr> |
| <tr><td><code>env</code></td> |
| <td>Return first match of <code>note</code>, <code>reqenv</code>, |
| <code>osenv</code></td></tr> |
| <tr><td><code>tolower</code></td> |
| <td>Convert string to lower case</td></tr> |
| <tr><td><code>toupper</code></td> |
| <td>Convert string to uppser case</td></tr> |
| <tr><td><code>escape</code></td> |
| <td>Escape special characters in %hex encoding</td></tr> |
| <tr><td><code>unescape</code></td> |
| <td>Unescape %hex encoded string, leaving URL-special characters encoded (XXX: describe better)</td></tr> |
| <tr><td><code>file</code></td> |
| <td>Read contents from a file</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>There are no built-in list-valued functions. <module>mod_ssl</module> |
| provides <code>PeerExtList</code>. See the description of |
| <directive module="mod_ssl">SSLRequire</directive> for details |
| (but <code>PeerExtList</code> is also usable outside |
| of <directive module="mod_ssl">SSLRequire</directive>).</p> |
| |
| </section> |
| |
| <section id="other"> |
| <title>Other</title> |
| |
| <table border="1" style="zebra"> |
| <columnspec><column width=".2"/><column width=".2"/><column width=".6"/></columnspec> |
| |
| <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> |
| <tr><td><code>/regexp/</code></td> |
| <td><code>m#regexp#</code></td> |
| <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> |
| <tr><td><code>$0 ... $9</code></td> |
| <td></td> |
| <td>Regular expression backreferences</td></tr> |
| </table> |
| |
| <section id="rebackref"> |
| <title>Regular expression backreferences</title> |
| <p>The strings <code>$0</code> ... <code>$9</code> allow to reference |
| 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> |
| |
| </manualpage> |
