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   8 <title>Expressions in Apache HTTP Server - Apache HTTP Server</title>
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  14 <p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.html">Directives</a> | <a href="./faq/">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p>
  15 <p class="apache">Apache HTTP Server Version 2.3</p>
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  17 <div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="./images/left.gif" /></a></div>
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  19 <a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="./">Version 2.3</a></div><div id="page-content"><div id="preamble"><h1>Expressions in Apache HTTP Server</h1>
  20 <div class="toplang">
  21 <p><span>Available Languages: </span><a href="./en/expr.html" title="English">&nbsp;en&nbsp;</a></p>
  22 </div>
  23
  24     <p>Historically, there are several syntax variants for expressions used to express
  25         a condition in the different modules of the Apache HTTP Server.
  26         There is some ongoing effort to only use a single variant, called <em>ap_expr</em>,
  27         for all configuration directives.
  28         This document describes the <em>ap_expr</em> expression parser.
  29     </p>
  30   </div>
  31 <div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#grammar">Grammar in BNF notation</a></li>
  32 <li><img alt="" src="./images/down.gif" /> <a href="#vars">Variables</a></li>
  33 <li><img alt="" src="./images/down.gif" /> <a href="#binop">Binary operators</a></li>
  34 <li><img alt="" src="./images/down.gif" /> <a href="#unnop">Unary operators</a></li>
  35 <li><img alt="" src="./images/down.gif" /> <a href="#functions">Functions</a></li>
  36 </ul></div>
  37 <div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
  38 <div class="section">
  39 <h2><a name="grammar" id="grammar">Grammar in BNF notation</a></h2>
  40
  41 <blockquote>
  42 <pre>
  43 expr        ::= "<strong>true</strong>" | "<strong>false</strong>"
  44               | "<strong>!</strong>" expr
  45               | expr "<strong>&amp;&amp;</strong>" expr
  46               | expr "<strong>||</strong>" expr
  47               | "<strong>(</strong>" expr "<strong>)</strong>"
  48               | comp
  49
  50 comp        ::= stringcomp
  51               | integercomp
  52               | unaryop word
  53               | word binaryop word
  54               | word "<strong>in</strong>" "<strong>{</strong>" wordlist "<strong>}</strong>"
  55               | word "<strong>in</strong>" listfunction
  56               | word "<strong>=~</strong>" regex
  57               | word "<strong>!~</strong>" regex
  58
  59
  60 stringcomp  ::= word "<strong>==</strong>" word | word "<strong>eq</strong>" word
  61               | word "<strong>!=</strong>" word | word "<strong>ne</strong>" word
  62               | word "<strong>&lt;</strong>"  word | word "<strong>lt</strong>" word
  63               | word "<strong>&lt;=</strong>" word | word "<strong>le</strong>" word
  64               | word "<strong>&gt;</strong>"  word | word "<strong>gt</strong>" word
  65               | word "<strong>&gt;=</strong>" word | word "<strong>ge</strong>" word
  66
  67 integercomp ::= word "<strong>-eq</strong>" word | word "<strong>eq</strong>" word
  68               | word "<strong>-ne</strong>" word | word "<strong>ne</strong>" word
  69               | word "<strong>-lt</strong>" word | word "<strong>lt</strong>" word
  70               | word "<strong>-le</strong>" word | word "<strong>le</strong>" word
  71               | word "<strong>-gt</strong>" word | word "<strong>gt</strong>" word
  72               | word "<strong>-ge</strong>" word | word "<strong>ge</strong>" word
  73
  74 wordlist    ::= word
  75               | wordlist "<strong>,</strong>" word
  76
  77 word        ::= word "<strong>.</strong>" word
  78               | digit
  79               | "<strong>'</strong>" string "<strong>'</strong>"
  80               | "<strong>"</strong>" string "<strong>"</strong>"
  81               | variable
  82               | function
  83
  84 string      ::= stringpart
  85               | string stringpart
  86
  87 stringpart  ::= cstring
  88               | variable
  89
  90 cstring     ::= ...
  91 digit       ::= [0-9]+
  92
  93 variable    ::= "<strong>%{</strong>" varname "<strong>}</strong>"
  94               | "<strong>%{</strong>" funcname "<strong>:</strong>" funcargs "<strong>}</strong>"
  95
  96 function     ::= funcname "<strong>(</strong>" word "<strong>)</strong>"
  97
  98 listfunction ::= listfuncname "<strong>(</strong>" word "<strong>)</strong>"
  99 </pre>
 100 </blockquote>
 101
 102 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
 103 <div class="section">
 104 <h2><a name="vars" id="vars">Variables</a></h2>
 105
 106 <p>XXX: not all vars are available in all request phases</p>
 107
 108     <p>Request headers (XXX:see req function)</p>
 109
 110     <table class="bordered"><tr class="header"><th>Name</th></tr>
 111 <tr><td><code>HTTP_ACCEPT</code></td></tr>
 112 <tr class="odd"><td><code>HTTP_FORWARDED</code></td></tr>
 113 <tr><td><code>HTTP_HOST</code></td></tr>
 114 <tr class="odd"><td><code>HTTP_PROXY_CONNECTION</code></td></tr>
 115 <tr><td><code>HTTP_REFERER</code></td></tr>
 116 <tr class="odd"><td><code>HTTP_USER_AGENT</code></td></tr>
 117 </table>
 118
 119     <p>Other request related variables</p>
 120
 121     <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
 122 <tr><td><code>REQUEST_METHOD</code></td>
 123         <td /></tr>
 124 <tr class="odd"><td><code>REQUEST_SCHEME</code></td>
 125         <td /></tr>
 126 <tr><td><code>REQUEST_URI</code></td>
 127         <td /></tr>
 128 <tr class="odd"><td><code>REQUEST_FILENAME</code></td>
 129         <td /></tr>
 130 <tr><td><code>REMOTE_HOST</code></td>
 131         <td /></tr>
 132 <tr class="odd"><td><code>REMOTE_IDENT</code></td>
 133         <td /></tr>
 134 <tr><td><code>REMOTE_USER</code></td>
 135         <td /></tr>
 136 <tr class="odd"><td><code>SERVER_ADMIN</code></td>
 137         <td /></tr>
 138 <tr><td><code>SERVER_NAME</code></td>
 139         <td /></tr>
 140 <tr class="odd"><td><code>SERVER_PORT</code></td>
 141         <td /></tr>
 142 <tr><td><code>SERVER_PROTOCOL</code></td>
 143         <td /></tr>
 144 <tr class="odd"><td><code>SCRIPT_FILENAME</code></td>
 145         <td /></tr>
 146 <tr><td><code>PATH_INFO</code></td>
 147         <td /></tr>
 148 <tr class="odd"><td><code>QUERY_STRING</code></td>
 149         <td /></tr>
 150 <tr><td><code>IS_SUBREQ</code></td>
 151         <td /></tr>
 152 <tr class="odd"><td><code>DOCUMENT_ROOT</code></td>
 153         <td /></tr>
 154 <tr><td><code>AUTH_TYPE</code></td>
 155         <td /></tr>
 156 <tr class="odd"><td><code>THE_REQUEST</code></td>
 157         <td /></tr>
 158 <tr><td><code>CONTENT_TYPE</code></td>
 159         <td /></tr>
 160 <tr class="odd"><td><code>HANDLER</code></td>
 161         <td /></tr>
 162 <tr><td><code>REMOTE_ADDR</code></td>
 163         <td /></tr>
 164 <tr class="odd"><td><code>HTTPS</code></td>
 165         <td /></tr>
 166 <tr><td><code>IPV6</code></td>
 167         <td /></tr>
 168 <tr class="odd"><td><code>REQUEST_LOG_ID</code></td>
 169         <td /></tr>
 170 <tr><td><code>CONN_LOG_ID</code></td>
 171         <td /></tr>
 172 </table>
 173
 174     <p>Misc variables</p>
 175
 176     <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
 177 <tr><td><code>TIME_YEAR</code></td>
 178         <td /></tr>
 179 <tr class="odd"><td><code>TIME_MON</code></td>
 180         <td /></tr>
 181 <tr><td><code>TIME_DAY</code></td>
 182         <td /></tr>
 183 <tr class="odd"><td><code>TIME_HOUR</code></td>
 184         <td /></tr>
 185 <tr><td><code>TIME_MIN</code></td>
 186         <td /></tr>
 187 <tr class="odd"><td><code>TIME_SEC</code></td>
 188         <td /></tr>
 189 <tr><td><code>TIME_WDAY</code></td>
 190         <td /></tr>
 191 <tr class="odd"><td><code>TIME</code></td>
 192         <td /></tr>
 193 <tr><td><code>SERVER_SOFTWARE</code></td>
 194         <td /></tr>
 195 <tr class="odd"><td><code>API_VERSION</code></td>
 196         <td /></tr>
 197 </table>
 198
 199 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
 200 <div class="section">
 201 <h2><a name="binop" id="binop">Binary operators</a></h2>
 202
 203
 204     <p>With the exception of some built-in comparison operators, binary
 205     operators have the form "<code>-[a-zA-Z][a-zA-Z0-9_]+</code>", i.e. a
 206     minus and at least two characters. The name is not case sensitive.
 207     Modules may register additional binary operators.</p>
 208
 209     <table class="bordered"><tr class="header"><th>Name</th><th>Alternative</th> <th>Description</th></tr>
 210 <tr><td><code>==</code></td>
 211         <td><code>=</code></td>
 212         <td>String equality</td></tr>
 213 <tr class="odd"><td><code>!=</code></td>
 214         <td />
 215         <td>String inequality</td></tr>
 216 <tr><td><code>&lt;</code></td>
 217         <td />
 218         <td>String less than</td></tr>
 219 <tr class="odd"><td><code>&lt;=</code></td>
 220         <td />
 221         <td>String less than or equal</td></tr>
 222 <tr><td><code>&gt;</code></td>
 223         <td />
 224         <td>String greater than</td></tr>
 225 <tr class="odd"><td><code>&gt;=</code></td>
 226         <td />
 227         <td>String greater than or equal</td></tr>
 228 <tr><td><code>-eq</code></td>
 229         <td><code>eq</code></td>
 230         <td>Integer equality</td></tr>
 231 <tr class="odd"><td><code>-ne</code></td>
 232         <td><code>ne</code></td>
 233         <td>Integer inequality</td></tr>
 234 <tr><td><code>-lt</code></td>
 235         <td><code>lt</code></td>
 236         <td>Integer less than</td></tr>
 237 <tr class="odd"><td><code>-le</code></td>
 238         <td><code>le</code></td>
 239         <td>Integer less than or equal</td></tr>
 240 <tr><td><code>-gt</code></td>
 241         <td><code>gt</code></td>
 242         <td>Integer greater than</td></tr>
 243 <tr class="odd"><td><code>-ge</code></td>
 244         <td><code>ge</code></td>
 245         <td>Integer greater than or equal</td></tr>
 246 </table>
 247
 248 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
 249 <div class="section">
 250 <h2><a name="unnop" id="unnop">Unary operators</a></h2>
 251
 252
 253     <p>Unary operators have the form "<code>-[a-zA-Z]</code>", i.e. a
 254     minus and one character. The name <em>is</em> case sensitive.
 255     Modules may register additional unary operators.</p>
 256
 257     <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
 258 <tr><td><code>-n</code></td>
 259         <td>String is not empty</td></tr>
 260 <tr class="odd"><td><code>-z</code></td>
 261         <td>String is empty</td></tr>
 262 </table>
 263
 264 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
 265 <div class="section">
 266 <h2><a name="functions" id="functions">Functions</a></h2>
 267
 268
 269     <p>Normal string-valued functions take one string as argument and return
 270     a string. Functions names are not case sensitive.
 271     Modules may register additional functions.</p>
 272
 273     <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
 274 <tr><td><code>req</code>, <code>http</code></td>
 275         <td>Get HTTP request header</td></tr>
 276 <tr class="odd"><td><code>resp</code></td>
 277         <td>Get HTTP response header</td></tr>
 278 <tr><td><code>reqenv</code></td>
 279         <td>Lookup request environment variable</td></tr>
 280 <tr class="odd"><td><code>osenv</code></td>
 281         <td>Lookup operating system environment variable</td></tr>
 282 <tr><td><code>note</code></td>
 283         <td>Lookup request environment variable</td></tr>
 284 <tr class="odd"><td><code>env</code></td>
 285         <td>Return first match of <code>note</code>, <code>reqenv</code>,
 286             <code>osenv</code></td></tr>
 287 <tr><td><code>tolower</code></td>
 288         <td>Convert string to lower case</td></tr>
 289 <tr class="odd"><td><code>toupper</code></td>
 290         <td>Convert string to uppser case</td></tr>
 291 <tr><td><code>escape</code></td>
 292         <td>Escape special characters in %hex encoding</td></tr>
 293 <tr class="odd"><td><code>unescape</code></td>
 294         <td>Unescape %hex encoded string, leaving URL-special characters encoded (XXX: describe better)</td></tr>
 295 <tr><td><code>file</code></td>
 296         <td>Read contents from a file</td></tr>
 297 </table>
 298
 299     <p>In addition to string-valued functions, there are also list-valued functions which
 300     take one string as argument and return a wordlist, i.e. a list of strings. The wordlist
 301     can be used with the special <code>-in</code> operator.
 302     Functions names are not case sensitive.
 303     Modules may register additional functions.</p>
 304
 305     <p>There are no built-in list-valued functions. <code class="module"><a href="./mod/mod_ssl.html">mod_ssl</a></code>'s
 306     <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code> provides
 307     <code>PeerExtList</code>.</p>
 308
 309 </div></div>
 310 <div class="bottomlang">
 311 <p><span>Available Languages: </span><a href="./en/expr.html" title="English">&nbsp;en&nbsp;</a></p>
 312 </div><div id="footer">
 313 <p class="apache">Copyright 2010 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
 314 <p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.html">Directives</a> | <a href="./faq/">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p></div>
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