+++ /dev/null
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
- "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-
-<html xmlns="http://www.w3.org/1999/xhtml">
- <head>
- <meta name="generator" content="HTML Tidy, see www.w3.org" />
-
- <title>Request Processing in Apache 2.0</title>
- </head>
- <!-- Background white, links blue (unvisited), navy (visited), red (active) -->
-
- <body bgcolor="#FFFFFF" text="#000000" link="#0000FF"
- vlink="#000080" alink="#FF0000">
- <!--#include virtual="header.html" -->
-
- <h1>Request Processing in Apache 2.0</h1>
-
- <p>Warning - this is a first (fast) draft that needs further
- revision!</p>
-
- <p>Several changes in Apache 2.0 affect the internal request
- processing mechanics. Module authors need to be aware of these
- changes so they may take advantage of the optimizations and
- security enhancements.</p>
-
- <p>The first major change is to the subrequest and redirect
- mechanisms. There were a number of different code paths in
- Apache 1.3 to attempt to optimize subrequest or redirect
- behavior. As patches were introduced to 2.0, these
- optimizations (and the server behavior) were quickly broken due
- to this duplication of code. All duplicate code has been folded
- back into <code>ap_process_internal_request()</code> to prevent
- the code from falling out of sync again.</p>
-
- <p>This means that much of the existing code was 'unoptimized'.
- It is the Apache HTTP Project's first goal to create a robust
- and correct implementation of the HTTP server RFC. Additional
- goals include security, scalability and optimization. New
- methods were sought to optimize the server (beyond the
- performance of Apache 1.3) without introducing fragile or
- insecure code.</p>
-
- <h2>The Request Processing Cycle</h2>
-
- <p>All requests pass through
- <code>ap_process_request_internal()</code> in request.c,
- including subrequests and redirects. If a module doesn't pass
- generated requests through this code, the author is cautioned
- that the module may be broken by future changes to request
- processing.</p>
-
- <p>To streamline requests, the module author can take advantage
- of the hooks offered to drop out of the request cycle early, or
- to bypass core Apache hooks which are irrelevant (and costly in
- terms of CPU.)</p>
-
- <h2>The Request Parsing Phase</h2>
-
- <h3>Unescapes the URL</h3>
-
- <p>The request's parsed_uri path is unescaped, once and only
- once, at the beginning of internal request processing.</p>
-
- <p>This step is bypassed if the proxyreq flag is set, or the
- parsed_uri.path element is unset. The module has no further
- control of this one-time unescape operation, either failing to
- unescape or multiply unescaping the URL leads to security
- reprecussions.</p>
-
- <h3>Strips Parent and This Elements from the URI</h3>
-
- <p>All <code>/../</code> and <code>/./</code> elements are
- removed by <code>ap_getparents()</code>. This helps to ensure
- the path is (nearly) absolute before the request processing
- continues.</p>
-
- <p>This step cannot be bypassed.</p>
-
- <h3>Initial URI Location Walk</h3>
-
- <p>Every request is subject to an
- <code>ap_location_walk()</code> call. This ensures that
- <Location > sections are consistently enforced for all
- requests. If the request is an internal redirect or a
- sub-request, it may borrow some or all of the processing from
- the previous or parent request's ap_location_walk, so this step
- is generally very efficient after processing the main
- request.</p>
-
- <h3>Hook: translate_name</h3>
-
- <p>Modules can determine the file name, or alter the given URI
- in this step. For example, mod_vhost_alias will translate the
- URI's path into the configured virtual host, mod_alias will
- translate the path to an alias path, and if the request falls
- back on the core, the DocumentRoot is prepended to the request
- resource.</p>
-
- <p>If all modules DECLINE this phase, an error 500 is returned
- to the browser, and a "couldn't translate name" error is logged
- automatically.</p>
-
- <h3>Hook: map_to_storage</h3>
-
- <p>After the file or correct URI was determined, the
- appropriate per-dir configurations are merged together. For
- example, mod_proxy compares and merges the appropriate
- <Proxy > sections. If the URI is nothing more than a
- local (non-proxy) TRACE request, the core handles the request
- and returns DONE. If no module answers this hook with OK or
- DONE, the core will run the request filename against the
- <Directory > and <Files > sections. If the request
- 'filename' isn't an absolute, legal filename, a note is set for
- later termination.</p>
-
- <h3>Initial URI Location Walk</h3>
-
- <p>Every request is hardened by a second
- <code>ap_location_walk()</code> call. This reassures that a
- translated request is still subjected to the configured
- <Location > sections. The request again borrows some or
- all of the processing from its previous location_walk above,
- so this step is almost always very efficient unless the
- translated URI mapped to a substantially different path or
- Virtual Host.</p>
-
- <h3>Hook: header_parser</h3>
-
- <p>The main request then parses the client's headers. This
- prepares the remaining request processing steps to better serve
- the client's request.</p>
-
- <h2>The Security Phase</h2>
-
- <p>Needs Documentation. Code is;</p>
-<pre>
- switch (ap_satisfies(r)) {
- case SATISFY_ALL:
- case SATISFY_NOSPEC:
- if ((access_status = ap_run_access_checker(r)) != 0) {
- return decl_die(access_status, "check access", r);
- }
- if (ap_some_auth_required(r)) {
- if (((access_status = ap_run_check_user_id(r)) != 0) || !ap_auth_type(r)) {
- return decl_die(access_status, ap_auth_type(r)
- ? "check user. No user file?"
- : "perform authentication. AuthType not set!", r);
- }
- if (((access_status = ap_run_auth_checker(r)) != 0) || !ap_auth_type(r)) {
- return decl_die(access_status, ap_auth_type(r)
- ? "check access. No groups file?"
- : "perform authentication. AuthType not set!", r);
- }
- }
- break;
- case SATISFY_ANY:
- if (((access_status = ap_run_access_checker(r)) != 0) || !ap_auth_type(r)) {
- if (!ap_some_auth_required(r)) {
- return decl_die(access_status, ap_auth_type(r)
- ? "check access"
- : "perform authentication. AuthType not set!", r);
- }
- if (((access_status = ap_run_check_user_id(r)) != 0) || !ap_auth_type(r)) {
- return decl_die(access_status, ap_auth_type(r)
- ? "check user. No user file?"
- : "perform authentication. AuthType not set!", r);
- }
- if (((access_status = ap_run_auth_checker(r)) != 0) || !ap_auth_type(r)) {
- return decl_die(access_status, ap_auth_type(r)
- ? "check access. No groups file?"
- : "perform authentication. AuthType not set!", r);
- }
- }
- break;
- }
-</pre>
-
- <h2>The Preparation Phase</h2>
-
- <h3>Hook: type_checker</h3>
-
- <p>The modules have an opportunity to test the URI or filename
- against the target resource, and set mime information for the
- request. Both mod_mime and mod_mime_magic use this phase to
- compare the file name or contents against the administrator's
- configuration and set the content type, language, character set
- and request handler. Some modules may set up their filters or
- other request handling parameters at this time.</p>
-
- <p>If all modules DECLINE this phase, an error 500 is returned
- to the browser, and a "couldn't find types" error is logged
- automatically.</p>
-
- <h3>Hook: fixups</h3>
-
- <p>Many modules are 'trounced' by some phase above. The fixups
- phase is used by modules to 'reassert' their ownership or force
- the request's fields to their appropriate values. It isn't
- always the cleanest mechanism, but occasionally it's the only
- option.</p>
-
- <h2>The Handler Phase</h2>
-
- <p>This phase is <strong><em>not</em></strong> part of the
- processing in <code>ap_process_request_internal()</code>. Many
- modules prepare one or more subrequests prior to creating any
- content at all. After the core, or a module calls
- <code>ap_process_request_internal()</code> it then calls
- <code>ap_invoke_handler()</code> to generate the request.</p>
-
- <h3>Hook: insert_filter</h3>
-
- <p>Modules that transform the content in some way can insert
- their values and override existing filters, such that if the
- user configured a more advanced filter out-of-order, then the
- module can move its order as need be. There is no result code,
- so actions in this hook better be trusted to always succeed.</p>
-
- <h3>Hook: handler</h3>
-
- <p>The module finally has a chance to serve the request in its
- handler hook. Note that not every prepared request is sent to
- the handler hook. Many modules, such as mod_autoindex, will
- create subrequests for a given URI, and then never serve the
- subrequest, but simply lists it for the user. Remember not to
- put required teardown from the hooks above into this module,
- but register pool cleanups against the request pool to free
- resources as required.</p>
- <!--#include virtual="footer.html" -->
- </body>
-</html>
-
--- /dev/null
+<?xml version="1.0" encoding="ISO-8859-1"?>
+<!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><!--
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ This file is generated from xml source: DO NOT EDIT
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ -->
+<title>Request Processing in Apache 2.0 - Apache HTTP Server</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 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="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
+<p class="apache">Apache HTTP Server Version 2.1</p>
+<img alt="" src="../images/feather.gif" /></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-project/">Documentation</a> > <a href="../">Version 2.1</a></div><div id="page-content"><div id="preamble"><h1>Request Processing in Apache 2.0</h1>
+ <div class="warning"><h3>Warning</h3>
+ <p>Warning - this is a first (fast) draft that needs further
+ revision!</p>
+ </div>
+
+ <p>Several changes in Apache 2.0 affect the internal request
+ processing mechanics. Module authors need to be aware of these
+ changes so they may take advantage of the optimizations and
+ security enhancements.</p>
+
+ <p>The first major change is to the subrequest and redirect
+ mechanisms. There were a number of different code paths in
+ Apache 1.3 to attempt to optimize subrequest or redirect
+ behavior. As patches were introduced to 2.0, these
+ optimizations (and the server behavior) were quickly broken due
+ to this duplication of code. All duplicate code has been folded
+ back into <code>ap_process_internal_request()</code> to prevent
+ the code from falling out of sync again.</p>
+
+ <p>This means that much of the existing code was 'unoptimized'.
+ It is the Apache HTTP Project's first goal to create a robust
+ and correct implementation of the HTTP server RFC. Additional
+ goals include security, scalability and optimization. New
+ methods were sought to optimize the server (beyond the
+ performance of Apache 1.3) without introducing fragile or
+ insecure code.</p>
+</div>
+<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#processing">The Request Processing Cycle</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#parsing">The Request Parsing Phase</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#security">The Security Phase</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#preparation">The Preparation Phase</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#handler">The Handler Phase</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="processing" id="processing">The Request Processing Cycle</a></h2>
+ <p>All requests pass through <code>ap_process_request_internal()</code>
+ in <code>request.c</code>, including subrequests and redirects. If a module
+ doesn't pass generated requests through this code, the author is cautioned
+ that the module may be broken by future changes to request
+ processing.</p>
+
+ <p>To streamline requests, the module author can take advantage
+ of the hooks offered to drop out of the request cycle early, or
+ to bypass core Apache hooks which are irrelevant (and costly in
+ terms of CPU.)</p>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="parsing" id="parsing">The Request Parsing Phase</a></h2>
+ <h3><a name="unescape" id="unescape">Unescapes the URL</a></h3>
+ <p>The request's <code>parsed_uri</code> path is unescaped, once and only
+ once, at the beginning of internal request processing.</p>
+
+ <p>This step is bypassed if the proxyreq flag is set, or the
+ <code>parsed_uri.path</code> element is unset. The module has no further
+ control of this one-time unescape operation, either failing to
+ unescape or multiply unescaping the URL leads to security
+ reprecussions.</p>
+
+
+ <h3><a name="strip" id="strip">Strips Parent and This Elements from the
+ URI</a></h3>
+ <p>All <code>/../</code> and <code>/./</code> elements are
+ removed by <code>ap_getparents()</code>. This helps to ensure
+ the path is (nearly) absolute before the request processing
+ continues.</p>
+
+ <p>This step cannot be bypassed.</p>
+
+
+ <h3><a name="inital-location-walk" id="inital-location-walk">Initial URI Location Walk</a></h3>
+ <p>Every request is subject to an
+ <code>ap_location_walk()</code> call. This ensures that
+ <code class="directive"><a href="../mod/core.html#location"><Location></a></code> sections
+ are consistently enforced for all requests. If the request is an internal
+ redirect or a sub-request, it may borrow some or all of the processing
+ from the previous or parent request's ap_location_walk, so this step
+ is generally very efficient after processing the main request.</p>
+
+
+ <h3><a name="translate_name" id="translate_name">translate_name</a></h3>
+ <p>Modules can determine the file name, or alter the given URI
+ in this step. For example, <code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> will
+ translate the URI's path into the configured virtual host,
+ <code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code> will translate the path to an alias path,
+ and if the request falls back on the core, the <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code> is prepended to the request resource.</p>
+
+ <p>If all modules <code>DECLINE</code> this phase, an error 500 is
+ returned to the browser, and a "couldn't translate name" error is logged
+ automatically.</p>
+
+
+ <h3><a name="map_to_storage" id="map_to_storage">Hook: map_to_storage</a></h3>
+ <p>After the file or correct URI was determined, the
+ appropriate per-dir configurations are merged together. For
+ example, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> compares and merges the appropriate
+ <code class="directive"><a href="../mod/mod_proxy.html#proxy"><Proxy></a></code> sections.
+ If the URI is nothing more than a local (non-proxy) <code>TRACE</code>
+ request, the core handles the request and returns <code>DONE</code>.
+ If no module answers this hook with <code>OK</code> or <code>DONE</code>,
+ the core will run the request filename against the <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code> and <code class="directive"><a href="../mod/core.html#files"><Files></a></code> sections. If the request
+ 'filename' isn't an absolute, legal filename, a note is set for
+ later termination.</p>
+
+
+ <h3><a name="location-walk" id="location-walk">URI Location Walk</a></h3>
+ <p>Every request is hardened by a second
+ <code>ap_location_walk()</code> call. This reassures that a
+ translated request is still subjected to the configured
+ <code class="directive"><a href="../mod/core.html#location"><Location></a></code> sections.
+ The request again borrows some or all of the processing from its previous
+ <code>location_walk</code> above, so this step is almost always very
+ efficient unless the translated URI mapped to a substantially different
+ path or Virtual Host.</p>
+
+
+ <h3><a name="header_parser" id="header_parser">Hook: header_parser</a></h3>
+ <p>The main request then parses the client's headers. This
+ prepares the remaining request processing steps to better serve
+ the client's request.</p>
+
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="security" id="security">The Security Phase</a></h2>
+ <p>Needs Documentation. Code is:</p>
+
+ <div class="example"><pre>
+switch (ap_satisfies(r)) {
+case SATISFY_ALL:
+case SATISFY_NOSPEC:
+ if ((access_status = ap_run_access_checker(r)) != 0) {
+ return decl_die(access_status, "check access", r);
+ }
+
+ if (ap_some_auth_required(r)) {
+ if (((access_status = ap_run_check_user_id(r)) != 0)
+ || !ap_auth_type(r)) {
+ return decl_die(access_status, ap_auth_type(r)
+ ? "check user. No user file?"
+ : "perform authentication. AuthType not set!",
+ r);
+ }
+
+ if (((access_status = ap_run_auth_checker(r)) != 0)
+ || !ap_auth_type(r)) {
+ return decl_die(access_status, ap_auth_type(r)
+ ? "check access. No groups file?"
+ : "perform authentication. AuthType not set!",
+ r);
+ }
+ }
+ break;
+
+case SATISFY_ANY:
+ if (((access_status = ap_run_access_checker(r)) != 0)) {
+ if (!ap_some_auth_required(r)) {
+ return decl_die(access_status, "check access", r);
+ }
+
+ if (((access_status = ap_run_check_user_id(r)) != 0)
+ || !ap_auth_type(r)) {
+ return decl_die(access_status, ap_auth_type(r)
+ ? "check user. No user file?"
+ : "perform authentication. AuthType not set!",
+ r);
+ }
+
+ if (((access_status = ap_run_auth_checker(r)) != 0)
+ || !ap_auth_type(r)) {
+ return decl_die(access_status, ap_auth_type(r)
+ ? "check access. No groups file?"
+ : "perform authentication. AuthType not set!",
+ r);
+ }
+ }
+ break;
+}</pre></div>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="preparation" id="preparation">The Preparation Phase</a></h2>
+ <h3><a name="type_checker" id="type_checker">Hook: type_checker</a></h3>
+ <p>The modules have an opportunity to test the URI or filename
+ against the target resource, and set mime information for the
+ request. Both <code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code> and
+ <code class="module"><a href="../mod/mod_mime_magic.html">mod_mime_magic</a></code> use this phase to compare the file
+ name or contents against the administrator's configuration and set the
+ content type, language, character set and request handler. Some modules
+ may set up their filters or other request handling parameters at this
+ time.</p>
+
+ <p>If all modules <code>DECLINE</code> this phase, an error 500 is
+ returned to the browser, and a "couldn't find types" error is logged
+ automatically.</p>
+
+
+ <h3><a name="fixups" id="fixups">Hook: fixups</a></h3>
+ <p>Many modules are 'trounced' by some phase above. The fixups
+ phase is used by modules to 'reassert' their ownership or force
+ the request's fields to their appropriate values. It isn't
+ always the cleanest mechanism, but occasionally it's the only
+ option.</p>
+
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="handler" id="handler">The Handler Phase</a></h2>
+ <p>This phase is <strong>not</strong> part of the processing in
+ <code>ap_process_request_internal()</code>. Many
+ modules prepare one or more subrequests prior to creating any
+ content at all. After the core, or a module calls
+ <code>ap_process_request_internal()</code> it then calls
+ <code>ap_invoke_handler()</code> to generate the request.</p>
+
+ <h3><a name="insert_filter" id="insert_filter">Hook: insert_filter</a></h3>
+ <p>Modules that transform the content in some way can insert
+ their values and override existing filters, such that if the
+ user configured a more advanced filter out-of-order, then the
+ module can move its order as need be. There is no result code,
+ so actions in this hook better be trusted to always succeed.</p>
+
+
+ <h3><a name="hook_handler" id="hook_handler">Hook: handler</a></h3>
+ <p>The module finally has a chance to serve the request in its
+ handler hook. Note that not every prepared request is sent to
+ the handler hook. Many modules, such as <code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code>,
+ will create subrequests for a given URI, and then never serve the
+ subrequest, but simply lists it for the user. Remember not to
+ put required teardown from the hooks above into this module,
+ but register pool cleanups against the request pool to free
+ resources as required.</p>
+
+</div></div>
+<div id="footer">
+<p class="apache">Maintained by the <a href="http://httpd.apache.org/docs-project/">Apache HTTP Server Documentation Project</a></p>
+<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>
+</body></html>
\ No newline at end of file
--- /dev/null
+<?xml version="1.0" encoding="UTF-8" ?>
+<!DOCTYPE manualpage SYSTEM "../style/manualpage.dtd">
+<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
+
+<manualpage>
+<relativepath href=".."/>
+
+<title>Request Processing in Apache 2.0</title>
+
+<summary>
+ <note type="warning"><title>Warning</title>
+ <p>Warning - this is a first (fast) draft that needs further
+ revision!</p>
+ </note>
+
+ <p>Several changes in Apache 2.0 affect the internal request
+ processing mechanics. Module authors need to be aware of these
+ changes so they may take advantage of the optimizations and
+ security enhancements.</p>
+
+ <p>The first major change is to the subrequest and redirect
+ mechanisms. There were a number of different code paths in
+ Apache 1.3 to attempt to optimize subrequest or redirect
+ behavior. As patches were introduced to 2.0, these
+ optimizations (and the server behavior) were quickly broken due
+ to this duplication of code. All duplicate code has been folded
+ back into <code>ap_process_internal_request()</code> to prevent
+ the code from falling out of sync again.</p>
+
+ <p>This means that much of the existing code was 'unoptimized'.
+ It is the Apache HTTP Project's first goal to create a robust
+ and correct implementation of the HTTP server RFC. Additional
+ goals include security, scalability and optimization. New
+ methods were sought to optimize the server (beyond the
+ performance of Apache 1.3) without introducing fragile or
+ insecure code.</p>
+</summary>
+
+<section id="processing"><title>The Request Processing Cycle</title>
+ <p>All requests pass through <code>ap_process_request_internal()</code>
+ in <code>request.c</code>, including subrequests and redirects. If a module
+ doesn't pass generated requests through this code, the author is cautioned
+ that the module may be broken by future changes to request
+ processing.</p>
+
+ <p>To streamline requests, the module author can take advantage
+ of the hooks offered to drop out of the request cycle early, or
+ to bypass core Apache hooks which are irrelevant (and costly in
+ terms of CPU.)</p>
+</section>
+
+<section id="parsing"><title>The Request Parsing Phase</title>
+ <section id="unescape"><title>Unescapes the URL</title>
+ <p>The request's <code>parsed_uri</code> path is unescaped, once and only
+ once, at the beginning of internal request processing.</p>
+
+ <p>This step is bypassed if the proxyreq flag is set, or the
+ <code>parsed_uri.path</code> element is unset. The module has no further
+ control of this one-time unescape operation, either failing to
+ unescape or multiply unescaping the URL leads to security
+ reprecussions.</p>
+ </section>
+
+ <section id="strip"><title>Strips Parent and This Elements from the
+ URI</title>
+ <p>All <code>/../</code> and <code>/./</code> elements are
+ removed by <code>ap_getparents()</code>. This helps to ensure
+ the path is (nearly) absolute before the request processing
+ continues.</p>
+
+ <p>This step cannot be bypassed.</p>
+ </section>
+
+ <section id="inital-location-walk"><title>Initial URI Location Walk</title>
+ <p>Every request is subject to an
+ <code>ap_location_walk()</code> call. This ensures that
+ <directive type="section" module="core">Location</directive> sections
+ are consistently enforced for all requests. If the request is an internal
+ redirect or a sub-request, it may borrow some or all of the processing
+ from the previous or parent request's ap_location_walk, so this step
+ is generally very efficient after processing the main request.</p>
+ </section>
+
+ <section id="translate_name"><title>translate_name</title>
+ <p>Modules can determine the file name, or alter the given URI
+ in this step. For example, <module>mod_vhost_alias</module> will
+ translate the URI's path into the configured virtual host,
+ <module>mod_alias</module> will translate the path to an alias path,
+ and if the request falls back on the core, the <directive module="core"
+ >DocumentRoot</directive> is prepended to the request resource.</p>
+
+ <p>If all modules <code>DECLINE</code> this phase, an error 500 is
+ returned to the browser, and a "couldn't translate name" error is logged
+ automatically.</p>
+ </section>
+
+ <section id="map_to_storage"><title>Hook: map_to_storage</title>
+ <p>After the file or correct URI was determined, the
+ appropriate per-dir configurations are merged together. For
+ example, <module>mod_proxy</module> compares and merges the appropriate
+ <directive module="mod_proxy" type="section">Proxy</directive> sections.
+ If the URI is nothing more than a local (non-proxy) <code>TRACE</code>
+ request, the core handles the request and returns <code>DONE</code>.
+ If no module answers this hook with <code>OK</code> or <code>DONE</code>,
+ the core will run the request filename against the <directive
+ module="core" type="section">Directory</directive> and <directive
+ module="core" type="section">Files</directive> sections. If the request
+ 'filename' isn't an absolute, legal filename, a note is set for
+ later termination.</p>
+ </section>
+
+ <section id="location-walk"><title>URI Location Walk</title>
+ <p>Every request is hardened by a second
+ <code>ap_location_walk()</code> call. This reassures that a
+ translated request is still subjected to the configured
+ <directive module="core" type="section">Location</directive> sections.
+ The request again borrows some or all of the processing from its previous
+ <code>location_walk</code> above, so this step is almost always very
+ efficient unless the translated URI mapped to a substantially different
+ path or Virtual Host.</p>
+ </section>
+
+ <section id="header_parser"><title>Hook: header_parser</title>
+ <p>The main request then parses the client's headers. This
+ prepares the remaining request processing steps to better serve
+ the client's request.</p>
+ </section>
+</section>
+
+<section id="security"><title>The Security Phase</title>
+ <p>Needs Documentation. Code is:</p>
+
+ <example><pre>
+switch (ap_satisfies(r)) {
+case SATISFY_ALL:
+case SATISFY_NOSPEC:
+ if ((access_status = ap_run_access_checker(r)) != 0) {
+ return decl_die(access_status, "check access", r);
+ }
+
+ if (ap_some_auth_required(r)) {
+ if (((access_status = ap_run_check_user_id(r)) != 0)
+ || !ap_auth_type(r)) {
+ return decl_die(access_status, ap_auth_type(r)
+ ? "check user. No user file?"
+ : "perform authentication. AuthType not set!",
+ r);
+ }
+
+ if (((access_status = ap_run_auth_checker(r)) != 0)
+ || !ap_auth_type(r)) {
+ return decl_die(access_status, ap_auth_type(r)
+ ? "check access. No groups file?"
+ : "perform authentication. AuthType not set!",
+ r);
+ }
+ }
+ break;
+
+case SATISFY_ANY:
+ if (((access_status = ap_run_access_checker(r)) != 0)) {
+ if (!ap_some_auth_required(r)) {
+ return decl_die(access_status, "check access", r);
+ }
+
+ if (((access_status = ap_run_check_user_id(r)) != 0)
+ || !ap_auth_type(r)) {
+ return decl_die(access_status, ap_auth_type(r)
+ ? "check user. No user file?"
+ : "perform authentication. AuthType not set!",
+ r);
+ }
+
+ if (((access_status = ap_run_auth_checker(r)) != 0)
+ || !ap_auth_type(r)) {
+ return decl_die(access_status, ap_auth_type(r)
+ ? "check access. No groups file?"
+ : "perform authentication. AuthType not set!",
+ r);
+ }
+ }
+ break;
+}</pre>
+ </example>
+</section>
+
+<section id="preparation"><title>The Preparation Phase</title>
+ <section id="type_checker"><title>Hook: type_checker</title>
+ <p>The modules have an opportunity to test the URI or filename
+ against the target resource, and set mime information for the
+ request. Both <module>mod_mime</module> and
+ <module>mod_mime_magic</module> use this phase to compare the file
+ name or contents against the administrator's configuration and set the
+ content type, language, character set and request handler. Some modules
+ may set up their filters or other request handling parameters at this
+ time.</p>
+
+ <p>If all modules <code>DECLINE</code> this phase, an error 500 is
+ returned to the browser, and a "couldn't find types" error is logged
+ automatically.</p>
+ </section>
+
+ <section id="fixups"><title>Hook: fixups</title>
+ <p>Many modules are 'trounced' by some phase above. The fixups
+ phase is used by modules to 'reassert' their ownership or force
+ the request's fields to their appropriate values. It isn't
+ always the cleanest mechanism, but occasionally it's the only
+ option.</p>
+ </section>
+</section>
+
+<section id="handler"><title>The Handler Phase</title>
+ <p>This phase is <strong>not</strong> part of the processing in
+ <code>ap_process_request_internal()</code>. Many
+ modules prepare one or more subrequests prior to creating any
+ content at all. After the core, or a module calls
+ <code>ap_process_request_internal()</code> it then calls
+ <code>ap_invoke_handler()</code> to generate the request.</p>
+
+ <section id="insert_filter"><title>Hook: insert_filter</title>
+ <p>Modules that transform the content in some way can insert
+ their values and override existing filters, such that if the
+ user configured a more advanced filter out-of-order, then the
+ module can move its order as need be. There is no result code,
+ so actions in this hook better be trusted to always succeed.</p>
+ </section>
+
+ <section id="hook_handler"><title>Hook: handler</title>
+ <p>The module finally has a chance to serve the request in its
+ handler hook. Note that not every prepared request is sent to
+ the handler hook. Many modules, such as <module>mod_autoindex</module>,
+ will create subrequests for a given URI, and then never serve the
+ subrequest, but simply lists it for the user. Remember not to
+ put required teardown from the hooks above into this module,
+ but register pool cleanups against the request pool to free
+ resources as required.</p>
+ </section>
+</section>
+</manualpage>
+
projects / thirdparty / apache / httpd.git / commitdiff
