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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 06:33:50 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 06:33:50 +0000 |
| commit | fe39ffb8b90ae4e002ed73fe98617cd590abb467 (patch) | |
| tree | b80e5956907d8aeaaffe4e4f0c068c0e6157ce8b /docs/manual/rewrite/tech.html.en | |
| parent | Initial commit. (diff) | |
| download | apache2-fe39ffb8b90ae4e002ed73fe98617cd590abb467.tar.xz apache2-fe39ffb8b90ae4e002ed73fe98617cd590abb467.zip | |
Adding upstream version 2.4.56.upstream/2.4.56upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
| -rw-r--r-- | docs/manual/rewrite/tech.html.en | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/docs/manual/rewrite/tech.html.en b/docs/manual/rewrite/tech.html.en new file mode 100644 index 0000000..5207ec7 --- /dev/null +++ b/docs/manual/rewrite/tech.html.en @@ -0,0 +1,205 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head> +<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" /> +<!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>Apache mod_rewrite Technical Details - Apache HTTP Server Version 2.4</title> +<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" /> +<script src="../style/scripts/prettify.min.js" type="text/javascript"> +</script> + +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<body id="manual-page"><div id="page-header"> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> +<p class="apache">Apache HTTP Server Version 2.4</p> +<img alt="" src="../images/feather.png" /></div> +<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> +<div id="path"> +<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.4</a> > <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>Apache mod_rewrite Technical Details</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/rewrite/tech.html" title="English"> en </a> | +<a href="../fr/rewrite/tech.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p> +</div> + +<p>This document discusses some of the technical details of mod_rewrite +and URL matching.</p> +</div> +<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#InternalAPI">API Phases</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#InternalRuleset">Ruleset Processing</a></li> +</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module documentation</a></li><li><a href="intro.html">mod_rewrite introduction</a></li><li><a href="remapping.html">Redirection and remapping</a></li><li><a href="access.html">Controlling access</a></li><li><a href="vhosts.html">Virtual hosts</a></li><li><a href="proxy.html">Proxying</a></li><li><a href="rewritemap.html">Using RewriteMap</a></li><li><a href="advanced.html">Advanced techniques</a></li><li><a href="avoid.html">When not to use mod_rewrite</a></li><li><a href="#comments_section">Comments</a></li></ul></div> +<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="InternalAPI" id="InternalAPI">API Phases</a></h2> + + <p>The Apache HTTP Server handles requests in several phases. At + each of these phases, one or more modules may be called upon to + handle that portion of the request lifecycle. Phases include things + like URL-to-filename translation, authentication, authorization, + content, and logging. (This is not an exhaustive list.)</p> + + <p>mod_rewrite acts in two of these phases (or "hooks", as they are + often called) to influence how URLs may be rewritten.</p> + + <p>First, it uses the URL-to-filename translation hook, which occurs + after the HTTP request has been read, but before any authorization + starts. Secondly, it uses the Fixup hook, which is after the + authorization phases, and after per-directory configuration files + (<code>.htaccess</code> files) have been read, but before the + content handler is called.</p> + + <p>So, after a request comes in and a corresponding server or + virtual host has been determined, the rewriting engine starts + processing any <code>mod_rewrite</code> directives appearing in the + per-server configuration. (i.e., in the main server configuration file + and <code class="directive"><a href="../mod/core.html#virtualhost"><Virtualhost></a></code> + sections.) This happens in the URL-to-filename phase.</p> + + <p>A few steps later, once the final data directories have been found, + the per-directory configuration directives (<code>.htaccess</code> + files and <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code> blocks) are applied. This + happens in the Fixup phase.</p> + + <p>In each of these cases, mod_rewrite rewrites the + <code>REQUEST_URI</code> either to a new URL, or to a filename.</p> + + <p>In per-directory context (i.e., within <code>.htaccess</code> files + and <code>Directory</code> blocks), these rules are being applied + after a URL has already been translated to a filename. Because of + this, the URL-path that mod_rewrite initially compares <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directives against + is the full filesystem path to the translated filename with the current + directories path (including a trailing slash) removed from the front.</p> + + <p> To illustrate: If rules are in /var/www/foo/.htaccess and a request + for /foo/bar/baz is being processed, an expression like ^bar/baz$ would + match.</p> + + <p> If a substitution is made in per-directory context, a new internal + subrequest is issued with the new URL, which restarts processing of the + request phases. If the substitution is a relative path, the <code class="directive"><a href="../mod/mod_rewrite.html#rewritebase">RewriteBase</a></code> directive + determines the URL-path prefix prepended to the substitution. + In per-directory context, care must be taken to + create rules which will eventually (in some future "round" of per-directory + rewrite processing) not perform a substitution to avoid looping. + (See <a href="http://wiki.apache.org/httpd/RewriteLooping">RewriteLooping</a> + for further discussion of this problem.)</p> + + <p>Because of this further manipulation of the URL in per-directory + context, you'll need to take care to craft your rewrite rules + differently in that context. In particular, remember that the + leading directory path will be stripped off of the URL that your + rewrite rules will see. Consider the examples below for further + clarification.</p> + + <table class="bordered"> + + <tr> + <th>Location of rule</th> + <th>Rule</th> + </tr> + + <tr> + <td>VirtualHost section</td> + <td>RewriteRule "^/images/(.+)\.jpg" "/images/$1.gif"</td> + </tr> + + <tr> + <td>.htaccess file in document root</td> + <td>RewriteRule "^images/(.+)\.jpg" "images/$1.gif"</td> + </tr> + + <tr> + <td>.htaccess file in images directory</td> + <td>RewriteRule "^(.+)\.jpg" "$1.gif"</td> + </tr> + + </table> + + <p>For even more insight into how mod_rewrite manipulates URLs in + different contexts, you should consult the <a href="../mod/mod_rewrite.html#logging">log entries</a> made during + rewriting.</p> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="InternalRuleset" id="InternalRuleset">Ruleset Processing</a></h2> + + <p>Now when mod_rewrite is triggered in these two API phases, it + reads the configured rulesets from its configuration + structure (which itself was either created on startup for + per-server context or during the directory walk of the Apache + kernel for per-directory context). Then the URL rewriting + engine is started with the contained ruleset (one or more + rules together with their conditions). The operation of the + URL rewriting engine itself is exactly the same for both + configuration contexts. Only the final result processing is + different.</p> + + <p>The order of rules in the ruleset is important because the + rewriting engine processes them in a special (and not very + obvious) order. The rule is this: The rewriting engine loops + through the ruleset rule by rule (<code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directives) and + when a particular rule matches it optionally loops through + existing corresponding conditions (<code>RewriteCond</code> + directives). For historical reasons the conditions are given + first, and so the control flow is a little bit long-winded. See + Figure 1 for more details.</p> +<p class="figure"> + <img src="../images/rewrite_process_uri.png" alt="Flow of RewriteRule and RewriteCond matching" /><br /> + <dfn>Figure 1:</dfn>The control flow through the rewriting ruleset +</p> + <p>First the URL is matched against the + <em>Pattern</em> of each rule. If it fails, mod_rewrite + immediately stops processing this rule, and continues with the + next rule. If the <em>Pattern</em> matches, mod_rewrite looks + for corresponding rule conditions (RewriteCond directives, + appearing immediately above the RewriteRule in the configuration). + If none are present, it substitutes the URL with a new value, which is + constructed from the string <em>Substitution</em>, and goes on + with its rule-looping. But if conditions exist, it starts an + inner loop for processing them in the order that they are + listed. For conditions, the logic is different: we don't match + a pattern against the current URL. Instead we first create a + string <em>TestString</em> by expanding variables, + back-references, map lookups, <em>etc.</em> and then we try + to match <em>CondPattern</em> against it. If the pattern + doesn't match, the complete set of conditions and the + corresponding rule fails. If the pattern matches, then the + next condition is processed until no more conditions are + available. If all conditions match, processing is continued + with the substitution of the URL with + <em>Substitution</em>.</p> + +</div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/rewrite/tech.html" title="English"> en </a> | +<a href="../fr/rewrite/tech.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p> +</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div> +<script type="text/javascript"><!--//--><![CDATA[//><!-- +var comments_shortname = 'httpd'; +var comments_identifier = 'http://httpd.apache.org/docs/2.4/rewrite/tech.html'; +(function(w, d) { + if (w.location.hostname.toLowerCase() == "httpd.apache.org") { + d.write('<div id="comments_thread"><\/div>'); + var s = d.createElement('script'); + s.type = 'text/javascript'; + s.async = true; + s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier; + (d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s); + } + else { + d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>'); + } +})(window, document); +//--><!]]></script></div><div id="footer"> +<p class="apache">Copyright 2023 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> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div><script type="text/javascript"><!--//--><![CDATA[//><!-- +if (typeof(prettyPrint) !== 'undefined') { + prettyPrint(); +} +//--><!]]></script> +</body></html>
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