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c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<parentdocument href="./">Developer</parentdocument>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh <title>Developing modules for the Apache HTTP Server 2.4</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<p>This document explains how you can develop modules for the Apache HTTP
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohServer 2.4</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<seealso><a href="request.html">Request Processing in Apache 2.4</a></seealso>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<seealso><a href="hooks.html">Apache 2.x Hook Functions</a></seealso>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="introduction"><title>Introduction</title>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="what"><title>What we will be discussing in this document</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThis document will discuss how you can easily create modules for the Apache
5408def46d326118d1a65a93a86b646008ed01e1humbedoohHTTP Server 2.4, by exploring an example module called
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<code>mod_example</code>. In the first part of this document, the purpose
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohof this module will be to calculate and print out various digest values for
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohexisting files on your web server, whenever we access the URL <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohhttp://hostname/filename.sum</code>. For instance, if we want to know the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohMD5 digest value of the file located at <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohhttp://www.example.com/index.html</code>, we would visit <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIn the second part of this document, which deals with configuration
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohdirective and context awareness, we will be looking at a module that simply
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwrite out its own configuration to the client.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="prerequisites"><title>Prerequisites</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohFirst and foremost, you are expected to have a basic knowledge of how the C
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohprogramming language works. In most cases, we will try to be as pedagogical
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohas possible and link to documents describing the functions used in the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohexamples, but there are also many cases where it is necessary to either
05664b3e454b2686379515dc6775bfbc51d3dc6ahumbedoohjust assume that "it works" or do some digging yourself into what the hows
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohand whys of various function calls.
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohLastly, you will need to have a basic understanding of how modules are
5408def46d326118d1a65a93a86b646008ed01e1humbedoohloaded and configured in the Apache HTTP Server, as well as how to get the headers for
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohApache if you do not have them already, as these are needed for compiling
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="compiling"><title>Compiling your module</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohTo compile the source code we are building in this document, we will be
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohusing <a href="/programs/apxs.html">APXS</a>. Assuming your source file
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohis called mod_example.c, compiling, installing and activating the module is
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohas simple as:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="basics"><title>Defining a module</title>
f0e7dbf8fc52d4a9fdf8e1cd5dd2d2da16bd55dbhumbedooh<img src="/images/build_a_mod_3.png" alt="Module name tags"/><br/>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohEvery module starts with the same declaration, or name tag if you will,
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohthat defines a module as <em>a separate entity within Apache</em>:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohmodule AP_MODULE_DECLARE_DATA example_module =
3d411f10000a79ea83afbd1760007e069b439486humbedooh STANDARD20_MODULE_STUFF,
3d411f10000a79ea83afbd1760007e069b439486humbedooh create_dir_conf, /* Per-directory configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh merge_dir_conf, /* Merge handler for per-directory configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh create_svr_conf, /* Per-server configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh merge_svr_conf, /* Merge handler for per-server configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh directives, /* Any directives we may have for httpd */
3d411f10000a79ea83afbd1760007e069b439486humbedooh register_hooks /* Our hook registering function */
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
5408def46d326118d1a65a93a86b646008ed01e1humbedoohThis bit of code lets the server know that we have now registered a new module
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohin the system, and that its name is <code>example_module</code>. The name
05664b3e454b2686379515dc6775bfbc51d3dc6ahumbedoohof the module is used primarily for two things:<br/>
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<li>Letting the server know how to load the module using the LoadModule</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Setting up a namespace for the module to use in configurations</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohFor now, we're only concerned with the first purpose of the module name,
f0e7dbf8fc52d4a9fdf8e1cd5dd2d2da16bd55dbhumbedoohwhich comes into play when we need to load the module:
5408def46d326118d1a65a93a86b646008ed01e1humbedoohIn essence, this tells the server to open up <code>mod_example.so</code> and look for a module
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohWithin this name tag of ours is also a bunch of references to how we would
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohlike to handle things: Which directives do we respond to in a configuration
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohfile or .htaccess, how do we operate within specific contexts, and what
5408def46d326118d1a65a93a86b646008ed01e1humbedoohhandlers are we interested in registering with the Apache HTTP service. We'll
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohreturn to all these elements later in this document.
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<section id="hooking"><title>Getting started: Hooking into the server</title>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="hook_intro"><title>An introduction to hooks</title>
5408def46d326118d1a65a93a86b646008ed01e1humbedoohWhen handling requests in Apache HTTP Server 2.4, the first thing you will need to do is
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohcreate a hook into the request handling process. A hook is essentially a
5408def46d326118d1a65a93a86b646008ed01e1humbedoohmessage telling the server that you are willing to either serve or at least
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohtake a glance at certain requests given by clients. All handlers, whether
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohit's mod_rewrite, mod_authn_*, mod_proxy and so on, are hooked into
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohspecific parts of the request process. As you are probably aware, modules
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohserve different purposes; Some are authentication/authorization handlers,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohothers are file or script handlers while some third modules rewrite URIs or
5408def46d326118d1a65a93a86b646008ed01e1humbedoohproxies content. Furthermore, in the end, it is up to the user of the server
5408def46d326118d1a65a93a86b646008ed01e1humbedoohhow and when each module will come into place. Thus, the server itself does not
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohpresume to know which module is responsible for handling a specific
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohrequest, and will ask each module whether they have an interest in a given
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohrequest or not. It is then up to each module to either gently decline
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohserving a request, accept serving it or flat out deny the request from
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohbeing served, as authentication/authorization modules do: <br/>
f0e7dbf8fc52d4a9fdf8e1cd5dd2d2da16bd55dbhumbedooh<img src="/images/build_a_mod_2.png" alt="Hook handling in httpd"/><br/>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohTo make it a bit easier for handlers such as our mod_example to know
5408def46d326118d1a65a93a86b646008ed01e1humbedoohwhether the client is requesting content we should handle or not, the server
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohhas directives for hinting to modules whether their assistance is needed or
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohnot. Two of these are <directive module="mod_mime">AddHandler</directive>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohand <directive module="core">SetHandler</directive>. Let's take a look at
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohan example using <directive module="mod_mime">AddHandler</directive>. In
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohour example case, we want every request ending with .sum to be served by
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<code>mod_example</code>, so we'll add a configuration directive that tells
5408def46d326118d1a65a93a86b646008ed01e1humbedoohthe server to do just that:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohAddHandler example-handler .sum
5408def46d326118d1a65a93a86b646008ed01e1humbedoohWhat this tells the server is the following: <em>Whenever we receive a request
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohfor a URI ending in .sum, we are to let all modules know that we are
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohlooking for whoever goes by the name of "example-handler" </em>.
5408def46d326118d1a65a93a86b646008ed01e1humbedoohThus, when a request is being served that ends in .sum, the server will let all
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohmodules know, that this request should be served by "example-handler
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh". As you will see later, when we start building mod_example, we will
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohcheck for this handler tag relayed by <code>AddHandler</code> and reply to
5408def46d326118d1a65a93a86b646008ed01e1humbedoohthe server based on the value of this tag.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="hook_declaration"><title>Hooking into httpd</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohTo begin with, we only want to create a simple handler, that replies to the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohclient browser when a specific URL is requested, so we won't bother setting
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohup configuration handlers and directives just yet. Our initial module
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohdefinition will look like this:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohmodule AP_MODULE_DECLARE_DATA example_module =
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh STANDARD20_MODULE_STUFF,
3d411f10000a79ea83afbd1760007e069b439486humbedooh register_hooks /* Our hook registering function */
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<p>This lets the server know that we are not interesting in anything fancy, we
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohjust want to hook onto the requests and possibly handle some of them. </p>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<p> The reference in our example declaration, <code>register_hooks</code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohis the name of a function we will create to manage how we hook onto the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohrequest process. In this example module, the function has just one purpose;
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohTo create a simple hook that gets called after all the rewrites, access
5408def46d326118d1a65a93a86b646008ed01e1humbedoohcontrol etc has been handled. Thus, we will let the server know, that we want
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohto hook into its process as one of the last modules:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic void register_hooks(apr_pool_t *pool)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Create a hook in the request handler, so we get called when a request arrives */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_hook_handler(example_handler, NULL, NULL, APR_HOOK_LAST);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThe <code>example_handler</code> reference is the function that will handle
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohthe request. We will discuss how to create a handler in the next chapter.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="hook_others"><title>Other useful hooks</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohHooking into the request handling phase is but one of many hooks that you
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohcan create. Some other ways of hooking are:
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<li><code>ap_hook_child_init</code>: Place a hook that executes when a child process is spawned (commonly used for initializing modules after the server has forked)</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>ap_hook_pre_config</code>: Place a hook that executes before any configuration data has been read (very early hook)</li>
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<li><code>ap_hook_post_config</code>: Place a hook that executes after configuration has been parsed, but before the server has forked</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>ap_hook_translate_name</code>: Place a hook that executes when a URI needs to be translated into a filename on the server (think <code>mod_rewrite</code>)</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="handling"><title>Building a handler</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohA handler is essentially a function that receives a callback when a request
5408def46d326118d1a65a93a86b646008ed01e1humbedoohto the server is made. It is passed a record of the current request (how it was
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohmade, which headers and requests were passed along, who's giving the
5408def46d326118d1a65a93a86b646008ed01e1humbedoohrequest and so on), and is put in charge of either telling the server that it's
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohnot interested in the request or handle the request with the tools provided.
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<section id="simple_handler"><title>A simple "Hello, world!"
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohhandler</title>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<p>Let's start off by making a very simple request handler
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohthat does the following:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Check that this is a request that should be served by "example-handler"</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Set the content type of our output to <code>text/html</code></li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Write "Hello, world!" back to the client browser</li>
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<li>Let the server know that we took care of this request and everything went fine</li>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohIn C code, our example handler will now look like this:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* First off, we need to check if this is a call for the "example-handler" handler.
3d411f10000a79ea83afbd1760007e069b439486humbedooh * If it is, we accept it and do our things, if not, we simply return DECLINED,
3d411f10000a79ea83afbd1760007e069b439486humbedooh * and the server will try somewhere else.
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (!r->handler || strcmp(r->handler, "example-handler")) return (DECLINED);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Now that we are handling this request, we'll write out "Hello, world!" to the client.
3d411f10000a79ea83afbd1760007e069b439486humbedooh * To do so, we must first set the appropriate content type, followed by our output.
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Hello, world!");
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Lastly, we must tell the server that we took care of this request and everything went fine.
3d411f10000a79ea83afbd1760007e069b439486humbedooh * We do so by simply returning the value OK to the server.
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohNow, we put all we have learned together and end up with a program that
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<a href="http://people.apache.org/~humbedooh/mods/examples/mod_example_1.c">mod_example_1.c</a>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh. The functions used in this example will be explained later in the section
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<a href= "#functions">"Some useful functions you should know"</a>.
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<section id="request_rec"><title>The request_rec structure</title>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<p>The most essential part of any request is the <em>request record
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh</em>. In a call to a handler function, this is represented by the <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohrequest_req* </code> structure passed along with every call that is made.
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThis struct, typically just refered to as <code>r</code> in modules,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohcontains all the information you need for your module to fully process any
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohHTTP request and respond accordingly.</p> <p>Some key elements of the <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohrequest_req </code> structure are:
3d411f10000a79ea83afbd1760007e069b439486humbedooh<li><code>r->handler (char*):</code> Contains the name of the handler the server is currently asking to do the handling of this request</li>
3d411f10000a79ea83afbd1760007e069b439486humbedooh<li><code>r->method (char*):</code> Contains the HTTP method being used, f.x. GET or POST</li>
3d411f10000a79ea83afbd1760007e069b439486humbedooh<li><code>r->filename (char*):</code> Contains the translated filename the client is requesting</li>
3d411f10000a79ea83afbd1760007e069b439486humbedooh<li><code>r->args (char*):</code> Contains the query string of the request, if any</li>
3d411f10000a79ea83afbd1760007e069b439486humbedooh<li><code>r->headers_in (apr_table_t*):</code> Contains all the headers sent by the client</li>
3d411f10000a79ea83afbd1760007e069b439486humbedooh<li><code>r->connection (conn_rec*):</code> A record containing information about the current connection</li>
3d411f10000a79ea83afbd1760007e069b439486humbedooh<li><code>r->useragent_ip (char*):</code> The IP address of the client connecting to us</li>
3d411f10000a79ea83afbd1760007e069b439486humbedooh<li><code>r->pool (apr_pool_t*)</code>: The memory pool of this request. We'll discuss this in the "
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<a href="#memory">Memory management</a>" chapter.</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohA complete list of all the values contained with in the <code>request_req</code> structure can be found in
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohthe <a href="http://svn.apache.org/repos/asf/httpd/httpd/trunk/include/httpd.h"><code>httpd.h</code></a> header
1784f96e3c9d47bf36a4d973d47e3857f260fc7dhumbedoohfile or at <a href="http://ci.apache.org/projects/httpd/trunk/doxygen/structrequest__rec.html">http://ci.apache.org/projects/httpd/trunk/doxygen/structrequest__rec.html</a>.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohLet's try out some of these variables in another example handler:<br/>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Set the appropriate content type */
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Print out the IP address of the client connecting to us: */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "<h2>Hello, %s!</h2>", r->useragent_ip);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* If we were reached through a GET or a POST request, be happy, else sad. */
3d411f10000a79ea83afbd1760007e069b439486humbedooh if ( !strcmp(r->method, "POST") || !strcmp(r->method, "GET") ) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rputs("You used a GET or a POST method, that makes us happy!<br/>", r);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rputs("You did not use POST or GET, that makes us sad :(<br/>", r);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Lastly, if there was a query string, let's print that too! */
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (r->args) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Your query string was: %s", r->args);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="return_value"><title>Return values</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohApache relies on return values from handlers to signify whether a request
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwas handled or not, and if so, whether the request went well or not. If a
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohmodule is not interested in handling a specific request, it should always
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohreturn the value <code>DECLINED</code>. If it is handling a request, it
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohshould either return the generic value <code>OK</code>, or a specific HTTP
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohstatus code, for example:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Return 404: Not found */
3d411f10000a79ea83afbd1760007e069b439486humbedooh return HTTP_NOT_FOUND;
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
05664b3e454b2686379515dc6775bfbc51d3dc6ahumbedoohReturning <code>OK</code> or a HTTP status code does not necessarily mean
5408def46d326118d1a65a93a86b646008ed01e1humbedoohthat the request will end. The server may still have other handlers that are
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohinterested in this request, for instance the logging modules which, upon a
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohsuccessful request, will write down a summary of what was requested and how
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohit went. To do a full stop and prevent any further processing after your
5408def46d326118d1a65a93a86b646008ed01e1humbedoohmodule is done, you can return the value <code>DONE</code> to let the server
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohknow that it should cease all activity on this request and carry on with
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohthe next, without informing other handlers.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>DECLINED</code>: We are not handling this request</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>OK</code>: We handled this request and it went well</li>
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<li><code>DONE</code>: We handled this request and the server should just close this thread without further processing</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<strong>HTTP specific return codes (excerpt):</strong>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>HTTP_OK (200)</code>: Request was okay</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>HTTP_MOVED_PERMANENTLY (301)</code>: The resource has moved to a new URL</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>HTTP_UNAUTHORIZED (401)</code>: Client is not authorized to visit this page</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>HTTP_FORBIDDEN (403)</code>: Permission denied</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>HTTP_NOT_FOUND (404)</code>: File not found</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>HTTP_INTERNAL_SERVER_ERROR (500)</code>: Internal server error (self explanatory)</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="functions"><title>Some useful functions you should know</title>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh <code>ap_rputs(const char *string, request_req *r)</code>: <br/>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh Sends a string of text to the client. This is a shorthand version of <a
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__APACHE__CORE__PROTO.html#gac827cd0537d2b6213a7c06d7c26cc36e">
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ap_rwrite</a>.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen<highlight language="c">ap_rputs("Hello, world!", r);</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh <a href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__APACHE__CORE__PROTO.html#ga5e91eb6ca777c9a427b2e82bf1eeb81d">ap_rprintf</a></code>: <br/>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh This function works just like <code>printf</code>, except it sends the result to the client.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen<highlight language="c">ap_rprintf(r, "Hello, %s!", r->useragent_ip);</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh <a href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__APACHE__CORE__PROTO.html#gaa2f8412c400197338ec509f4a45e4579">ap_set_content_type</a>(request_req *r, const char *type)</code>: <br/>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh Sets the content type of the output you are sending.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen<highlight language="c">ap_set_content_type(r, "text/plain"); /* force a raw text output */</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="memory"><title>Memory management</title>
5408def46d326118d1a65a93a86b646008ed01e1humbedoohManaging your resources in Apache HTTP Server 2.4 is quite easy, thanks to the memory pool
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohsystem. In essence, each server, connection and request have their own
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohmemory pool that gets cleaned up when its scope ends, e.g. when a request
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohis done or when a server process shuts down. All your module needs to do is
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohlatch onto this memory pool, and you won't have to worry about having to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohclean up after yourself - pretty neat, huh?
05664b3e454b2686379515dc6775bfbc51d3dc6ahumbedoohIn our module, we will primarily be allocating memory for each request, so
3d411f10000a79ea83afbd1760007e069b439486humbedoohit's appropriate to use the <code>r->pool</code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohreference when creating new objects. A few of the functions for allocating
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohmemory within a pool are:
2012d5e61d7a0648e2831321bad89085ea4718d3humbedooh<li><code>void* <a href="http://apr.apache.org/docs/apr/1.4/group__apr__pools.html#ga85f1e193c31d109affda72f9a92c6915">apr_palloc</a>(
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohapr_pool_t *p, apr_size_t size)</code>: Allocates <code>size</code> number of bytes in the pool for you</li>
2012d5e61d7a0648e2831321bad89085ea4718d3humbedooh<li><code>void* <a href="http://apr.apache.org/docs/apr/1.4/group__apr__pools.html#gaf61c098ad258069d64cdf8c0a9369f9e">apr_pcalloc</a>(
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohapr_pool_t *p, apr_size_t size)</code>: Allocates <code>size</code> number of bytes in the pool for you and sets all bytes to 0</li>
2012d5e61d7a0648e2831321bad89085ea4718d3humbedooh<li><code>char* <a href="http://apr.apache.org/docs/apr/1.4/group__apr__strings.html#gabc79e99ff19abbd7cfd18308c5f85d47">apr_pstrdup</a>(
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohapr_pool_t *p, const char *s)</code>: Creates a duplicate of the string <code>s</code>. This is useful for copying constant values so you can edit them</li>
2012d5e61d7a0648e2831321bad89085ea4718d3humbedooh<li><code>char* <a href="http://apr.apache.org/docs/apr/1.4/group__apr__strings.html#ga3eca76b8d293c5c3f8021e45eda813d8">apr_psprintf</a>(
5408def46d326118d1a65a93a86b646008ed01e1humbedoohapr_pool_t *p, const char *fmt, ...)</code>: Similar to <code>sprintf</code>, except the server supplies you with an appropriately allocated target variable</li>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<p>Let's put these functions into an example handler:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh const char* original = "You can't edit this!";
3d411f10000a79ea83afbd1760007e069b439486humbedooh int* integers;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Allocate space for 10 integer values and set them all to zero. */
3d411f10000a79ea83afbd1760007e069b439486humbedooh integers = apr_pcalloc(r->pool, sizeof(int)*10);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Create a copy of the 'original' variable that we can edit. */
3d411f10000a79ea83afbd1760007e069b439486humbedooh copy = apr_pstrdup(r->pool, original);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThis is all well and good for our module, which won't need any
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohpre-initialized variables or structures. However, if we wanted to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohinitialize something early on, before the requests come rolling in, we
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohcould simply add a call to a function in our <code>register_hooks</code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohfunction to sort it out:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic void register_hooks(apr_pool_t *pool)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Call a function that initializes some stuff */
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_init_function(pool);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Create a hook in the request handler, so we get called when a request arrives */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_hook_handler(example_handler, NULL, NULL, APR_HOOK_LAST);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIn this pre-request initialization function we would not be using the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohsame pool as we did when allocating resources for request-based functions.
5408def46d326118d1a65a93a86b646008ed01e1humbedoohInstead, we would use the pool given to us by the server for allocating memory
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohon a per-process based level.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="parsing"><title>Parsing request data</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIn our example module, we would like to add a feature, that checks which
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohtype of digest, MD5 or SHA1 the client would like to see. This could be
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohsolved by adding a query string to the request. A query string is typically
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohcomprised of several keys and values put together in a string, for instance
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<code>valueA=yes&valueB=no&valueC=maybe</code>. It is up to the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohmodule itself to parse these and get the data it requires. In our example,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwe'll be looking for a key called <code>digest</code>, and if set to <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohmd5</code>, we'll produce an MD5 digest, otherwise we'll produce a SHA1
5408def46d326118d1a65a93a86b646008ed01e1humbedoohSince the introduction of Apache HTTP Server 2.4, parsing request data from GET and
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohPOST requests have never been easier. All we require to parse both GET and
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohPOST data is four simple lines:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<a href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__apr__tables.html#gad7ea82d6608a4a633fc3775694ab71e4">apr_table_t</a> *GET;
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<a href="http://ci.apache.org/projects/httpd/trunk/doxygen/structapr__array__header__t.html">apr_array_header_t</a> *POST;
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<a href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__APACHE__CORE__SCRIPT.html#gaed25877b529623a4d8f99f819ba1b7bd">ap_args_to_table</a>(r, &GET);
3d411f10000a79ea83afbd1760007e069b439486humbedooh<a href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__APACHE__CORE__DAEMON.html#ga9d426b6382b49754d4f87c55f65af202">ap_parse_form_data</a>(r, NULL, &POST, -1, 8192);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIn our specific example module, we're looking for the <code>digest</code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohvalue from the query string, which now resides inside a table called <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohGET</code>. To extract this value, we need only perform a simple operation:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Get the "digest" key from the query string, if any. */
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *digestType = apr_table_get(GET, "digest");
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* If no key was returned, we will set a default value instead. */
3d411f10000a79ea83afbd1760007e069b439486humbedoohif (!digestType) digestType = "sha1";
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThe structures used for the POST and GET data are not exactly the same, so
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohif we were to fetch a value from POST data instead of the query string, we
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwould have to resort to a few more lines, as outlined in <a href="#get_post"
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh>this example</a> in the last chapter of this document.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="advanced_handler"><title>Making an advanced handler</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohNow that we have learned how to parse form data and manage our resources,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwe can move on to creating an advanced version of our module, that spits
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohout the MD5 or SHA1 digest of files:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh int rc, exists;
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_finfo_t finfo;
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_file_t *file;
3d411f10000a79ea83afbd1760007e069b439486humbedooh char *filename;
3d411f10000a79ea83afbd1760007e069b439486humbedooh char buffer[256];
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_size_t readBytes;
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_table_t *GET;
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_array_header_t *POST;
3d411f10000a79ea83afbd1760007e069b439486humbedooh const char *digestType;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Check that the "example-handler" handler is being called. */
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (!r->handler || strcmp(r->handler, "example-handler")) return (DECLINED);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Figure out which file is being requested by removing the .sum from it */
3d411f10000a79ea83afbd1760007e069b439486humbedooh filename = apr_pstrdup(r->pool, r->filename);
3d411f10000a79ea83afbd1760007e069b439486humbedooh filename[strlen(filename)-4] = 0; /* Cut off the last 4 characters. */
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Figure out if the file we request a sum on exists and isn't a directory */
3d411f10000a79ea83afbd1760007e069b439486humbedooh rc = apr_stat(&finfo, filename, APR_FINFO_MIN, r->pool);
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (rc == APR_SUCCESS) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh (finfo.filetype != APR_NOFILE)
3d411f10000a79ea83afbd1760007e069b439486humbedooh && !(finfo.filetype & APR_DIR)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (!exists) return HTTP_NOT_FOUND; /* Return a 404 if not found. */
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* If apr_stat failed, we're probably not allowed to check this file. */
3d411f10000a79ea83afbd1760007e069b439486humbedooh else return HTTP_FORBIDDEN;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Parse the GET and, optionally, the POST data sent to us */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_args_to_table(r, &GET);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_parse_form_data(r, NULL, &POST, -1, 8192);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Set the appropriate content type */
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Print a title and some general information */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "<h2>Information on %s:</h2>", filename);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "<b>Size:</b> %u bytes<br/>", finfo.size);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Get the digest type the client wants to see */
3d411f10000a79ea83afbd1760007e069b439486humbedooh digestType = apr_table_get(GET, "digest");
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (!digestType) digestType = "MD5";
3d411f10000a79ea83afbd1760007e069b439486humbedooh rc = apr_file_open(&file, filename, APR_READ, APR_OS_DEFAULT, r->pool);
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (rc == APR_SUCCESS) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Are we trying to calculate the MD5 or the SHA1 digest? */
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (!strcasecmp(digestType, "md5")) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Calculate the MD5 sum of the file */
3d411f10000a79ea83afbd1760007e069b439486humbedooh char chr[16];
3d411f10000a79ea83afbd1760007e069b439486humbedooh uint32_t num[4];
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_md5_ctx_t md5;
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_md5_init(&md5);
3d411f10000a79ea83afbd1760007e069b439486humbedooh readBytes = 256;
3d411f10000a79ea83afbd1760007e069b439486humbedooh while ( apr_file_read(file, buffer, &readBytes) == APR_SUCCESS ) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_md5_update(&md5, buffer, readBytes);
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_md5_final(digest.chr, &md5);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Print out the MD5 digest */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rputs("<b>MD5: </b><code>", r);
3d411f10000a79ea83afbd1760007e069b439486humbedooh for (n = 0; n < APR_MD5_DIGESTSIZE/4; n++) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "%08x", digest.num[n]);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rputs("</code>", r);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Print a link to the SHA1 version */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rputs("<br/><a href='?digest=sha1'>View the SHA1 hash instead</a>", r);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Calculate the SHA1 sum of the file */
3d411f10000a79ea83afbd1760007e069b439486humbedooh char chr[20];
3d411f10000a79ea83afbd1760007e069b439486humbedooh uint32_t num[5];
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_sha1_ctx_t sha1;
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_sha1_init(&sha1);
3d411f10000a79ea83afbd1760007e069b439486humbedooh readBytes = 256;
3d411f10000a79ea83afbd1760007e069b439486humbedooh while ( apr_file_read(file, buffer, &readBytes) == APR_SUCCESS ) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_sha1_update(&sha1, buffer, readBytes);
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_sha1_final(digest.chr, &sha1);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Print out the SHA1 digest */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rputs("<b>SHA1: </b><code>", r);
3d411f10000a79ea83afbd1760007e069b439486humbedooh for (n = 0; n < APR_SHA1_DIGESTSIZE/4; n++) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "%08x", digest.num[n]);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rputs("</code>", r);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Print a link to the MD5 version */
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rputs("<br/><a href='?digest=md5'>View the MD5 hash instead</a>", r);
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_file_close(file);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Let the server know that we responded to this request. */
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThis version in its entirity can be found here:
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<a href="http://people.apache.org/~humbedooh/mods/examples/mod_example_2.c">mod_example_2.c</a>.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="configuration"><title>Adding configuration options</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIn this next segment of this document, we will turn our eyes away from the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohdigest module and create a new example module, whose only function is to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwrite out its own configuration. The purpose of this is to examine how
5408def46d326118d1a65a93a86b646008ed01e1humbedoohthe server works with configuration, and what happens when you start writing
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohadvanced configurations
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohfor your modules.
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<section id="config_intro"><title>An introduction to configuration
f0e7dbf8fc52d4a9fdf8e1cd5dd2d2da16bd55dbhumbedoohdirectives</title>
f0e7dbf8fc52d4a9fdf8e1cd5dd2d2da16bd55dbhumbedoohIf you are reading this, then you probably already know
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwhat a configuration directive is. Simply put, a directive is a way of
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohtelling an individual module (or a set of modules) how to behave, such as
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohthese directives control how <code>mod_rewrite</code> works:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohRewriteEngine On
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohEach of these configuration directives are handled by a separate function,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohthat parses the parameters given and sets up a configuration accordingly.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="config_simple"><title>Making an example configuration</title>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<p>To begin with, we'll create a basic configuration in C-space:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohtypedef struct {
3d411f10000a79ea83afbd1760007e069b439486humbedooh int enabled; /* Enable or disable our module */
3d411f10000a79ea83afbd1760007e069b439486humbedooh const char *path; /* Some path to...something */
3d411f10000a79ea83afbd1760007e069b439486humbedooh int typeOfAction; /* 1 means action A, 2 means action B and so on */
3d411f10000a79ea83afbd1760007e069b439486humbedooh} example_config;
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohNow, let's put this into perspective by creating a very small module that
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohjust prints out a hard-coded configuration. You'll notice that we use the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<code>register_hooks</code> function for initializing the configuration
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohvalues to their defaults:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohtypedef struct {
3d411f10000a79ea83afbd1760007e069b439486humbedooh int enabled; /* Enable or disable our module */
3d411f10000a79ea83afbd1760007e069b439486humbedooh const char *path; /* Some path to...something */
3d411f10000a79ea83afbd1760007e069b439486humbedooh int typeOfAction; /* 1 means action A, 2 means action B and so on */
3d411f10000a79ea83afbd1760007e069b439486humbedooh} example_config;
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic example_config config;
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (!r->handler || strcmp(r->handler, "example-handler")) return(DECLINED);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Enabled: %u\n", config.enabled);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Path: %s\n", config.path);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "TypeOfAction: %x\n", config.typeOfAction);
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic void register_hooks(apr_pool_t *pool)
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_hook_handler(example_handler, NULL, NULL, APR_HOOK_LAST);
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Define our module as an entity and assign a function for registering hooks */
3d411f10000a79ea83afbd1760007e069b439486humbedoohmodule AP_MODULE_DECLARE_DATA example_module =
3d411f10000a79ea83afbd1760007e069b439486humbedooh STANDARD20_MODULE_STUFF,
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Per-directory configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Merge handler for per-directory configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Per-server configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Merge handler for per-server configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Any directives we may have for httpd */
3d411f10000a79ea83afbd1760007e069b439486humbedooh register_hooks /* Our hook registering function */
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohSo far so good. To access our new handler, we could add the following to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohour configuration:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<Location /example>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh SetHandler example-handler
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh</Location>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohWhen we visit, we'll see our current configuration being spit out by our
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<section id="register_directive"><title>Registering directives with the server</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohWhat if we want to change our configuration, not by hard-coding new values
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohinto the module, but by using either the httpd.conf file or possibly a
5408def46d326118d1a65a93a86b646008ed01e1humbedooh.htaccess file? It's time to let the server know that we want this to be
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohpossible. To do so, we must first change our <em>name tag</em> to include a
5408def46d326118d1a65a93a86b646008ed01e1humbedoohreference to the configuration directives we want to register with the server:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohmodule AP_MODULE_DECLARE_DATA example_module =
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh STANDARD20_MODULE_STUFF,
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Per-directory configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Merge handler for per-directory configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Per-server configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Merge handler for per-server configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_directives, /* Any directives we may have for httpd */
3d411f10000a79ea83afbd1760007e069b439486humbedooh register_hooks /* Our hook registering function */
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
5408def46d326118d1a65a93a86b646008ed01e1humbedoohThis will tell the server that we are now accepting directives from the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohconfiguration files, and that the structure called <code>example_directives
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh</code> holds information on what our directives are and how they work.
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohSince we have three different variables in our module configuration, we
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwill add a structure with three directives and a NULL at the end:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohstatic const command_rec example_directives[] =
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE1("exampleEnabled", example_set_enabled, NULL, RSRC_CONF, "Enable or disable mod_example"),
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE1("examplePath", example_set_path, NULL, RSRC_CONF, "The path to whatever"),
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE2("exampleAction", example_set_action, NULL, RSRC_CONF, "Special action value!"),
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
58738603be16903384f67947bbe524be985ebae7nd<img src="/images/build_a_mod_4.png" alt="Directives structure"/><br />
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohAs you can see, each directive needs at least 5 parameters set:
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<li><code><a href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__APACHE__CORE__CONFIG.html#ga07c7d22ae17805e61204463326cf9c34">AP_INIT_TAKE1</a></code>: This is a macro that tells the server that this directive takes one and only one argument.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohIf we required two arguments, we could use the macro <code><a href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__APACHE__CORE__CONFIG.html#gafaec43534fcf200f37d9fecbf9247c21">AP_INIT_TAKE2</a></code> and so on (refer to httpd_conf.h
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohfor more macros).</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>exampleEnabled</code>: This is the name of our directive. More precisely, it is what the user must put in his/her
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohconfiguration in order to invoke a configuration change in our module.</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>example_set_enabled</code>: This is a reference to a C function that parses the directive and sets the configuration
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohaccordingly. We will discuss how to make this in the following paragraph.</li>
05664b3e454b2686379515dc6775bfbc51d3dc6ahumbedooh<li><code>RSRC_CONF</code>: This tells the server where the directive is permitted. We'll go into details on this value in the
5408def46d326118d1a65a93a86b646008ed01e1humbedoohlater chapters, but for now, <code>RSRC_CONF</code> means that the server will only accept these directives in a server context.</li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><code>"Enable or disable...."</code>: This is simply a brief description of what the directive does.</li>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh(<em>The "missing" parameter in our definition, which is usually set to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<code>NULL</code>, is an optional function that can be run after the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohinitial function to parse the arguments have been run. This is usually
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohomitted, as the function for verifying arguments might as well be used to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohset them.</em>)
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="directive_handler"><title>The directive handler function</title>
5408def46d326118d1a65a93a86b646008ed01e1humbedoohNow that we've told the server to expect some directives for our module, it's
5408def46d326118d1a65a93a86b646008ed01e1humbedoohtime to make a few functions for handling these. What the server reads in the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohconfiguration file(s) is text, and so naturally, what it passes along to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohour directive handler is one or more strings, that we ourselves need to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohrecognize and act upon. You'll notice, that since we set our <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohexampleAction</code> directive to accept two arguments, its C function also
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohhas an additional parameter defined:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Handler for the "exambleEnabled" directive */
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_enabled(cmd_parms *cmd, void *cfg, const char *arg)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg, "on")) config.enabled = 1;
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Handler for the "examplePath" directive */
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_path(cmd_parms *cmd, void *cfg, const char *arg)
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Handler for the "exampleAction" directive */
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Let's pretend this one takes one argument (file or db), and a second (deny or allow), */
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* and we store it in a bit-wise manner. */
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_action(cmd_parms *cmd, void *cfg, const char *arg1, const char* arg2)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg1, "file")) config.typeOfAction = 0x01;
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg2, "deny")) config.typeOfAction += 0x10;
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="directive_complete"><title>Putting it all together</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohNow that we have our directives set up, and handlers configured for them,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwe can assemble our module into one big file:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedooh#include <stdio.h>
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Our configuration prototype and declaration:
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohtypedef struct {
3d411f10000a79ea83afbd1760007e069b439486humbedooh int enabled; /* Enable or disable our module */
3d411f10000a79ea83afbd1760007e069b439486humbedooh const char *path; /* Some path to...something */
3d411f10000a79ea83afbd1760007e069b439486humbedooh int typeOfAction; /* 1 means action A, 2 means action B and so on */
3d411f10000a79ea83afbd1760007e069b439486humbedooh} example_config;
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic example_config config;
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Our directive handlers:
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Handler for the "exambleEnabled" directive */
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_enabled(cmd_parms *cmd, void *cfg, const char *arg)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg, "on")) config.enabled = 1;
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Handler for the "examplePath" directive */
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_path(cmd_parms *cmd, void *cfg, const char *arg)
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Handler for the "exampleAction" directive */
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* Let's pretend this one takes one argument (file or db), and a second (deny or allow), */
3d411f10000a79ea83afbd1760007e069b439486humbedooh/* and we store it in a bit-wise manner. */
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_action(cmd_parms *cmd, void *cfg, const char *arg1, const char* arg2)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg1, "file")) config.typeOfAction = 0x01;
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg2, "deny")) config.typeOfAction += 0x10;
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh The directive structure for our name tag:
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic const command_rec example_directives[] =
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE1("exampleEnabled", example_set_enabled, NULL, RSRC_CONF, "Enable or disable mod_example"),
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE1("examplePath", example_set_path, NULL, RSRC_CONF, "The path to whatever"),
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE2("exampleAction", example_set_action, NULL, RSRC_CONF, "Special action value!"),
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Our module handler:
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!r->handler || strcmp(r->handler, "example-handler")) return(DECLINED);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Enabled: %u\n", config.enabled);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Path: %s\n", config.path);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "TypeOfAction: %x\n", config.typeOfAction);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh The hook registration function (also initializes the default config values):
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic void register_hooks(apr_pool_t *pool)
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_hook_handler(example_handler, NULL, NULL, APR_HOOK_LAST);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Our module name tag:
3d411f10000a79ea83afbd1760007e069b439486humbedooh ==============================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohmodule AP_MODULE_DECLARE_DATA example_module =
3d411f10000a79ea83afbd1760007e069b439486humbedooh STANDARD20_MODULE_STUFF,
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Per-directory configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Merge handler for per-directory configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Per-server configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Merge handler for per-server configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_directives, /* Any directives we may have for httpd */
3d411f10000a79ea83afbd1760007e069b439486humbedooh register_hooks /* Our hook registering function */
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIn our httpd.conf file, we can now change the hard-coded configuration by
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohadding a few lines:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohExampleEnabled On
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohExampleAction file allow
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohAnd thus we apply the configuration, visit <code>/example</code> on our
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohweb site, and we see the configuration has adapted to what we wrote in our
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohconfiguration file.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="context"><title>Context aware configurations</title>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="context_intro"><title>Introduction to context aware configurations</title>
5408def46d326118d1a65a93a86b646008ed01e1humbedoohIn Apache HTTP Server 2.4, different URLs, virtual hosts, directories etc can have very
5408def46d326118d1a65a93a86b646008ed01e1humbedoohdifferent meanings to the user of the server, and thus different contexts
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwithin which modules must operate. For example, let's assume you have this
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohconfiguration set up for mod_rewrite:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh RewriteCond %{HTTP_HOST} ^example.com$
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh</Directory>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh RewriteRule ^foobar$ index.php?foobar=true
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh</Directory>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIn this example, you will have set up two different contexts for
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohmod_rewrite:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Inside <code>/var/www</code>, all requests for <code>http://example.com</code> must go to <code>http://www.example.com</code></li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Inside <code>/var/www/sub</code>, all requests for <code>foobar</code> must go to <code>index.php?foobar=true</code></li>
5408def46d326118d1a65a93a86b646008ed01e1humbedoohIf mod_rewrite (or the entire server for that matter) wasn't context aware, then
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohthese rewrite rules would just apply to every and any request made,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohregardless of where and how they were made, but since the module can pull
5408def46d326118d1a65a93a86b646008ed01e1humbedoohthe context specific configuration straight from the server, it does not need
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohto know itself, which of the directives are valid in this context, since
5408def46d326118d1a65a93a86b646008ed01e1humbedoohthe server takes care of this.</p>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohSo how does a module get the specific configuration for the server,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohdirectory or location in question? It does so by making one simple call:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohexample_config *config = (example_config*) <a href="http://ci.apache.org/projects/httpd/trunk/doxygen/group__APACHE__CORE__CONFIG.html#ga1093a5908a384eacc929b028c79f2a02">ap_get_module_config</a>(r->per_dir_config, &example_module);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThat's it! Of course, a whole lot goes on behind the scenes, which we will
5408def46d326118d1a65a93a86b646008ed01e1humbedoohdiscuss in this chapter, starting with how the server came to know what our
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohconfiguration looks like, and how it came to be set up as it is in the
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohspecific context.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="context_base"><title>Our basic configuration setup</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh<p>In this chapter, we will be working with a slightly modified version of
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohour previous context structure. We will set a <code>context</code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohvariable that we can use to track which context configuration is being
5408def46d326118d1a65a93a86b646008ed01e1humbedoohused by the server in various places:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohtypedef struct {
3d411f10000a79ea83afbd1760007e069b439486humbedooh char context[256];
3d411f10000a79ea83afbd1760007e069b439486humbedooh char path[256];
3d411f10000a79ea83afbd1760007e069b439486humbedooh int typeOfAction;
3d411f10000a79ea83afbd1760007e069b439486humbedooh int enabled;
3d411f10000a79ea83afbd1760007e069b439486humbedooh} example_config;
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<!-- END EXAMPLE CODE -->
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<p>Our handler for requests will also be modified, yet still very simple:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!r->handler || strcmp(r->handler, "example-handler")) return(DECLINED);
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *config = (example_config*) ap_get_module_config(r->per_dir_config, &example_module);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf("Enabled: %u\n", config->enabled);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf("Path: %s\n", config->path);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf("TypeOfAction: %x\n", config->typeOfAction);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf("Context: %s\n", config->context);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<!-- END EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="context_which"><title>Choosing a context</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohBefore we can start making our module context aware, we must first define,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwhich contexts we will accept. As we saw in the previous chapter, defining
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooha directive required five elements be set:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohAP_INIT_TAKE1("exampleEnabled", example_set_enabled, NULL, RSRC_CONF, "Enable or disable mod_example"),
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<p>The <code>RSRC_CONF</code> definition told the server that we would only allow
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohthis directive in a global server context, but since we are now trying out
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooha context aware version of our module, we should set this to something
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohmore lenient, namely the value <code>ACCESS_CONF</code>, which lets us use
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohthe directive inside <Directory> and <Location> blocks.
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<section id="context_pool"><title>Using the server to allocate configuration slots</title>
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<p> A much smarter way to manage your configurations is by letting the server
d5f549d9022aee3727a1278486dc80124198ac26humbedoohhelp you create them. To do so, we must first start off by changing our
5408def46d326118d1a65a93a86b646008ed01e1humbedooh<em>name tag</em> to let the server know, that it should assist us in creating
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohand managing our configurations. Since we have chosen the per-directory
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh(or per-location) context for our module configurations, we'll add a
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohper-directory creator and merger function reference in our tag:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohmodule AP_MODULE_DECLARE_DATA example_module =
3d411f10000a79ea83afbd1760007e069b439486humbedooh STANDARD20_MODULE_STUFF,
3d411f10000a79ea83afbd1760007e069b439486humbedooh create_dir_conf, /* Per-directory configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh merge_dir_conf, /* Merge handler for per-directory configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Per-server configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Merge handler for per-server configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh directives, /* Any directives we may have for httpd */
3d411f10000a79ea83afbd1760007e069b439486humbedooh register_hooks /* Our hook registering function */
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedooh<!-- END EXAMPLE CODE -->
f0e7dbf8fc52d4a9fdf8e1cd5dd2d2da16bd55dbhumbedooh<section id="context_new"><title>Creating new context configurations</title>
5408def46d326118d1a65a93a86b646008ed01e1humbedoohNow that we have told the server to help us create and manage configurations,
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohour first step is to make a function for creating new, blank
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohconfigurations. We do so by creating the function we just referenced in
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohour name tag as the Per-directory configuration handler:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohvoid* example_create_dir_conf(apr_pool_t* pool, char* context) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh context = context ? context : "(undefined context)";
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *cfg = apr_pcalloc(pool, sizeof(example_config));
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Set some default values */
3d411f10000a79ea83afbd1760007e069b439486humbedooh strcpy(cfg->context, x);
3d411f10000a79ea83afbd1760007e069b439486humbedooh cfg->enabled = 0;
3d411f10000a79ea83afbd1760007e069b439486humbedooh cfg->typeOfAction = 0x11;
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
f0e7dbf8fc52d4a9fdf8e1cd5dd2d2da16bd55dbhumbedooh<section id="context_merge"><title>Merging configurations</title>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohOur next step in creating a context aware configuration is merging
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohconfigurations. This part of the process particularly apply to scenarios
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohwhere you have a parent configuration and a child, such as the following:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleEnable On
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleAction file allow
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh</Directory>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleAction file deny
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh</Directory>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIn this example, it is natural to assume that the directory <code>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh/var/www/subdir</code> should inherit the value set for the <code>/var/www
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedooh</code> directory, as we did not specify a <code>ExampleEnable</code> nor
5408def46d326118d1a65a93a86b646008ed01e1humbedoohan <code>ExamplePath</code> for this directory. The server does not presume to
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohknow if this is true, but cleverly does the following:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Creates a new configuration for <code>/var/www</code></li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Sets the configuration values according to the directives given for <code>/var/www</code></li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Creates a new configuration for <code>/var/www/subdir</code></li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li>Sets the configuration values according to the directives given for <code>/var/www/subdir</code></li>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<li><strong>Proposes a merge</strong> of the two configurations into a new configuration for <code>/var/www/subdir</code></li>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThis proposal is handled by the <code>merge_dir_conf</code> function we
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohreferenced in our name tag. The purpose of this function is to assess the
7bf47ee4f9e291a8b3843ac6577c896018ad3f12humbedoohtwo configurations and decide how they are to be merged:</p>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohvoid* merge_dir_conf(apr_pool_t* pool, void* BASE, void* ADD) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config* base = (example_config *) BASE ;
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config* add = (example_config *) ADD ;
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config* conf = (example_config *) create_dir_conf(pool, "Merged configuration");
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->enabled = ( add->enabled == 0 ) ? base->enabled : add->enabled ;
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->typeOfAction = add->typeOfAction ? add->typeOfAction : base->typeOfAction;
3d411f10000a79ea83afbd1760007e069b439486humbedooh strcpy(conf->path, strlen(add->path) ? add->path : base->path);
3d411f10000a79ea83afbd1760007e069b439486humbedooh return conf ;
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
f0e7dbf8fc52d4a9fdf8e1cd5dd2d2da16bd55dbhumbedooh<section id="context_example"><title>Trying out our new context aware configurations</title>
d5f549d9022aee3727a1278486dc80124198ac26humbedoohNow, let's try putting it all together to create a new module that is
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohcontext aware. First off, we'll create a configuration that lets us test
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohhow the module works:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<Location "/a">
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh SetHandler example-handler
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleEnabled on
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleAction file allow
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh</Location>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<Location "/a/b">
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleAction file deny
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleEnabled off
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh</Location>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<Location "/a/b/c">
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleAction db deny
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh ExampleEnabled on
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh</Location>
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohThen we'll assemble our module code. Note, that since we are now using our
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohname tag as reference when fetching configurations in our handler, I have
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohadded some prototypes to keep the compiler happy:
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedooh +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3d411f10000a79ea83afbd1760007e069b439486humbedooh +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3d411f10000a79ea83afbd1760007e069b439486humbedooh#include <stdio.h>
3d411f10000a79ea83afbd1760007e069b439486humbedooh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3d411f10000a79ea83afbd1760007e069b439486humbedooh Configuration structure
3d411f10000a79ea83afbd1760007e069b439486humbedooh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3d411f10000a79ea83afbd1760007e069b439486humbedoohtypedef struct
3d411f10000a79ea83afbd1760007e069b439486humbedooh char context[256];
3d411f10000a79ea83afbd1760007e069b439486humbedooh char path[256];
3d411f10000a79ea83afbd1760007e069b439486humbedooh int typeOfAction;
3d411f10000a79ea83afbd1760007e069b439486humbedooh int enabled;
3d411f10000a79ea83afbd1760007e069b439486humbedooh} example_config;
3d411f10000a79ea83afbd1760007e069b439486humbedooh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3d411f10000a79ea83afbd1760007e069b439486humbedooh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r);
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_enabled(cmd_parms *cmd, void *cfg, const char *arg);
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_path(cmd_parms *cmd, void *cfg, const char *arg);
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_action(cmd_parms *cmd, void *cfg, const char *arg1, const char *arg2);
3d411f10000a79ea83afbd1760007e069b439486humbedoohvoid *create_dir_conf(apr_pool_t *pool, char *context);
3d411f10000a79ea83afbd1760007e069b439486humbedoohvoid *merge_dir_conf(apr_pool_t *pool, void *BASE, void *ADD);
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic void register_hooks(apr_pool_t *pool);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3d411f10000a79ea83afbd1760007e069b439486humbedooh Configuration directives
3d411f10000a79ea83afbd1760007e069b439486humbedooh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic const command_rec directives[] =
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE1("exampleEnabled", example_set_enabled, NULL, ACCESS_CONF, "Enable or disable mod_example"),
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE1("examplePath", example_set_path, NULL, ACCESS_CONF, "The path to whatever"),
3d411f10000a79ea83afbd1760007e069b439486humbedooh AP_INIT_TAKE2("exampleAction", example_set_action, NULL, ACCESS_CONF, "Special action value!"),
3d411f10000a79ea83afbd1760007e069b439486humbedooh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3d411f10000a79ea83afbd1760007e069b439486humbedooh Our name tag
3d411f10000a79ea83afbd1760007e069b439486humbedooh ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3d411f10000a79ea83afbd1760007e069b439486humbedoohmodule AP_MODULE_DECLARE_DATA example_module =
3d411f10000a79ea83afbd1760007e069b439486humbedooh STANDARD20_MODULE_STUFF,
3d411f10000a79ea83afbd1760007e069b439486humbedooh create_dir_conf, /* Per-directory configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh merge_dir_conf, /* Merge handler for per-directory configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Per-server configuration handler */
3d411f10000a79ea83afbd1760007e069b439486humbedooh NULL, /* Merge handler for per-server configurations */
3d411f10000a79ea83afbd1760007e069b439486humbedooh directives, /* Any directives we may have for httpd */
3d411f10000a79ea83afbd1760007e069b439486humbedooh register_hooks /* Our hook registering function */
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Hook registration function
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic void register_hooks(apr_pool_t *pool)
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_hook_handler(example_handler, NULL, NULL, APR_HOOK_LAST);
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Our example web service handler
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_rec *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!r->handler || strcmp(r->handler, "example-handler")) return(DECLINED);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *config = (example_config *) ap_get_module_config(r->per_dir_config, &example_module);
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Enabled: %u\n", config->enabled);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Path: %s\n", config->path);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "TypeOfAction: %x\n", config->typeOfAction);
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "Context: %s\n", config->context);
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Handler for the "exambleEnabled" directive
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_enabled(cmd_parms *cmd, void *cfg, const char *arg)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *conf = (example_config *) cfg;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg, "on"))
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->enabled = 1;
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->enabled = 0;
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Handler for the "examplePath" directive
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_path(cmd_parms *cmd, void *cfg, const char *arg)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *conf = (example_config *) cfg;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh strcpy(conf->path, arg);
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Handler for the "exampleAction" directive ;
3d411f10000a79ea83afbd1760007e069b439486humbedooh Let's pretend this one takes one argument (file or db), and a second (deny or allow), ;
3d411f10000a79ea83afbd1760007e069b439486humbedooh and we store it in a bit-wise manner.
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *example_set_action(cmd_parms *cmd, void *cfg, const char *arg1, const char *arg2)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *conf = (example_config *) cfg;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg1, "file"))
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->typeOfAction = 0x01;
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->typeOfAction = 0x02;
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcasecmp(arg2, "deny"))
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->typeOfAction += 0x10;
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->typeOfAction += 0x20;
3d411f10000a79ea83afbd1760007e069b439486humbedooh return NULL;
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Function for creating new configurations for per-directory contexts
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohvoid *create_dir_conf(apr_pool_t *pool, char *context)
3d411f10000a79ea83afbd1760007e069b439486humbedooh context = context ? context : "Newly created configuration";
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *cfg = apr_pcalloc(pool, sizeof(example_config));
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh /* Set some default values */
3d411f10000a79ea83afbd1760007e069b439486humbedooh strcpy(cfg->context, context);
3d411f10000a79ea83afbd1760007e069b439486humbedooh cfg->enabled = 0;
3d411f10000a79ea83afbd1760007e069b439486humbedooh memset(cfg->path, 0, 256);
3d411f10000a79ea83afbd1760007e069b439486humbedooh cfg->typeOfAction = 0x00;
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedooh Merging function for configurations
3d411f10000a79ea83afbd1760007e069b439486humbedooh =======================================================================================================================
3d411f10000a79ea83afbd1760007e069b439486humbedoohvoid *merge_dir_conf(apr_pool_t *pool, void *BASE, void *ADD)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *base = (example_config *) BASE;
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *add = (example_config *) ADD;
3d411f10000a79ea83afbd1760007e069b439486humbedooh example_config *conf = (example_config *) create_dir_conf(pool, "Merged configuration");
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->enabled = (add->enabled == 0) ? base->enabled : add->enabled;
3d411f10000a79ea83afbd1760007e069b439486humbedooh conf->typeOfAction = add->typeOfAction ? add->typeOfAction : base->typeOfAction;
3d411f10000a79ea83afbd1760007e069b439486humbedooh strcpy(conf->path, strlen(add->path) ? add->path : base->path);
3d411f10000a79ea83afbd1760007e069b439486humbedooh return conf;
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
5408def46d326118d1a65a93a86b646008ed01e1humbedoohWe have now looked at how to create simple modules for Apache HTTP Server 2.4 and
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohconfiguring them. What you do next is entirely up to you, but it is my
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohhope that something valuable has come out of reading this documentation.
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohIf you have questions on how to further develop modules, you are welcome
9a76f548bf4b14aaf2e6cbf886851a630e3e2fefhumbedoohto join our <a href="http://httpd.apache.org/lists.html">mailing lists</a>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedoohor check out the rest of our documentation for further tips.
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="snippets"><title>Some useful snippets of code</title>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<section id="get_post"><title>Retrieve a variable from POST form data</title>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohconst char *read_post_value(const apr_array_header_t *fields, const char *key)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_table_entry_t *e = 0;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh e = (apr_table_entry_t *) fields->elts;
3d411f10000a79ea83afbd1760007e069b439486humbedooh for(i = 0; i < fields->nelts; i++) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(!strcmp(e[i].key, key)) return e[i].val;
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_req *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_array_header_t *POST;
3d411f10000a79ea83afbd1760007e069b439486humbedooh const char *value;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_parse_form_data(r, NULL, &POST, -1, 8192);
3d411f10000a79ea83afbd1760007e069b439486humbedooh value = read_post_value(POST, "valueA");
3d411f10000a79ea83afbd1760007e069b439486humbedooh if (!value) value = "(undefined)";
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "The value of valueA is: %s", value);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh <section id="headers_out"><title>Printing out every HTTP header received</title>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_req *r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh const apr_array_header_t *fields;
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_table_entry_t *e = 0;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh fields = apr_table_elts(r->headers_in);
3d411f10000a79ea83afbd1760007e069b439486humbedooh e = (apr_table_entry_t *) fields->elts;
3d411f10000a79ea83afbd1760007e069b439486humbedooh for(i = 0; i < fields->nelts; i++) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf(r, "<b>%s</b>: %s<br/>", e[i].key, e[i].val);
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh <section id="request_body"><title>Reading the request body into memory</title>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- BEGIN EXAMPLE CODE -->
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int util_read(request_rec *r, const char **rbuf, apr_off_t *size)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh int rc = OK;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh if((rc = ap_setup_client_block(r, REQUEST_CHUNKED_ERROR))) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(ap_should_client_block(r)) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh char argsbuffer[HUGE_STRING_LEN];
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_off_t rsize, len_read, rpos = 0;
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_off_t length = r->remaining;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh *rbuf = (const char *) apr_pcalloc(r->pool, (apr_size_t) (length + 1));
3d411f10000a79ea83afbd1760007e069b439486humbedooh *size = length;
3d411f10000a79ea83afbd1760007e069b439486humbedooh while((len_read = ap_get_client_block(r, argsbuffer, sizeof(argsbuffer))) > 0) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh if((rpos + len_read) > length) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh rsize = length - rpos;
3d411f10000a79ea83afbd1760007e069b439486humbedooh rsize = len_read;
3d411f10000a79ea83afbd1760007e069b439486humbedooh memcpy((char *) *rbuf + rpos, argsbuffer, (size_t) rsize);
3d411f10000a79ea83afbd1760007e069b439486humbedooh rpos += rsize;
3d411f10000a79ea83afbd1760007e069b439486humbedoohstatic int example_handler(request_req* r)
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh apr_off_t size;
3d411f10000a79ea83afbd1760007e069b439486humbedooh const char *buffer;
3d411f10000a79ea83afbd1760007e069b439486humbedooh /*~~~~~~~~~~~~~~~~*/
3d411f10000a79ea83afbd1760007e069b439486humbedooh if(util_read(r, &data, &size) == OK) {
3d411f10000a79ea83afbd1760007e069b439486humbedooh ap_rprintf("We read a request body that was %u bytes long", size);
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen </highlight>
c955b5a85313893f7bf55aaa5aacbd946cb41570humbedooh<!-- END EXAMPLE CODE -->
d29d9ab4614ff992b0e8de6e2b88d52b6f1f153erbowen</manualpage>