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| author | André Malo <nd@apache.org> | 2003-04-05 16:11:56 +0200 |
|---|---|---|
| committer | André Malo <nd@apache.org> | 2003-04-05 16:11:56 +0200 |
| commit | 9a65127b0dfdd09914457f7c768a387d01fe3fa2 (patch) | |
| tree | 38093537cbf74d1b5574737cf4fe20c504c8b0c2 /docs/manual/developer | |
| parent | new XML (diff) | |
| download | apache2-9a65127b0dfdd09914457f7c768a387d01fe3fa2.tar.xz apache2-9a65127b0dfdd09914457f7c768a387d01fe3fa2.zip | |
new XML
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@99235 13f79535-47bb-0310-9956-ffa450edef68
Diffstat (limited to 'docs/manual/developer')
| -rw-r--r-- | docs/manual/developer/request.html | 232 | ||||
| -rw-r--r-- | docs/manual/developer/request.html.en | 254 | ||||
| -rw-r--r-- | docs/manual/developer/request.xml | 240 |
3 files changed, 494 insertions, 232 deletions
diff --git a/docs/manual/developer/request.html b/docs/manual/developer/request.html deleted file mode 100644 index 4089862700..0000000000 --- a/docs/manual/developer/request.html +++ /dev/null @@ -1,232 +0,0 @@ -<!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> - diff --git a/docs/manual/developer/request.html.en b/docs/manual/developer/request.html.en new file mode 100644 index 0000000000..7cddabaaae --- /dev/null +++ b/docs/manual/developer/request.html.en @@ -0,0 +1,254 @@ +<?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 diff --git a/docs/manual/developer/request.xml b/docs/manual/developer/request.xml new file mode 100644 index 0000000000..d8479fc279 --- /dev/null +++ b/docs/manual/developer/request.xml @@ -0,0 +1,240 @@ +<?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> + |