path: root/docs/manual/mod/mod_lua.xml

<?xml version="1.0"?>
<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
<!-- $LastChangedRevision$ -->

<!--
 Licensed to the Apache Software Foundation (ASF) under one or more
 contributor license agreements.  See the NOTICE file distributed with
 this work for additional information regarding copyright ownership.
 The ASF licenses this file to You under the Apache License, Version 2.0
 (the "License"); you may not use this file except in compliance with
 the License.  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-->

<modulesynopsis metafile="mod_lua.xml.meta">

<name>mod_lua</name>

<description>Provides Lua hooks into various portions of the httpd
request processing</description>
<status>Extension</status>
<sourcefile>mod_lua.c</sourcefile>
<identifier>lua_module</identifier>
<compatibility>2.3 and later</compatibility>

<summary>
<p>This module allows the server to be extended with scripts written in the
Lua programming language.  The extension points (hooks) available with
<module>mod_lua</module> include many of the hooks available to
natively compiled Apache HTTP Server modules, such as mapping requests to
files, generating dynamic responses, access control, authentication, and
authorization</p>

<p>More information on the Lua programming language can be found at the
<a href="http://www.lua.org/">the Lua website</a>.</p>

<note type="warning"><title>Warning</title>
<p>This module holds a great deal of power over httpd, which is both a
strength and a potential security risk. It is <strong>not</strong> recommended
that you use this module on a server that is shared with users you do not
trust, as it can be abused to change the internal workings of httpd.</p>
</note>

</summary>

<section id="basicconf"><title>Basic Configuration</title>

<p>The basic module loading directive is</p>

<highlight language="config">
    LoadModule lua_module modules/mod_lua.so
</highlight>

<p>
<code>mod_lua</code> provides a handler named <code>lua-script</code>,
which can be used with a <directive
module="core">SetHandler</directive> or
<directive module="mod_mime">AddHandler</directive> directive:</p>

<highlight language="config">
&lt;Files "*.lua"&gt;
    SetHandler lua-script
&lt;/Files&gt;
</highlight>

<p>
This will cause <code>mod_lua</code> to handle requests for files
ending in <code>.lua</code> by invoking that file's
<code>handle</code> function.
</p>

<p>For more flexibility, see <directive>LuaMapHandler</directive>.
</p>

</section>

<section id="writinghandlers"><title>Writing Handlers</title>
<p> In the Apache HTTP Server API, the handler is a specific kind of hook
responsible for generating the response.  Examples of modules that include a
handler are <module>mod_proxy</module>, <module>mod_cgi</module>,
and <module>mod_status</module>.</p>

<p><code>mod_lua</code> always looks to invoke a Lua function for the handler, rather than
just evaluating a script body CGI style. A handler function looks
something like this:</p>


<highlight language="lua">
<strong>example.lua</strong><br/>
-- example handler

require "string"

--[[
     This is the default method name for Lua handlers, see the optional
     function-name in the LuaMapHandler directive to choose a different
     entry point.
--]]
function handle(r)
    r.content_type = "text/plain"

    if r.method == 'GET' then
        r:puts("Hello Lua World!\n")
        for k, v in pairs( r:parseargs() ) do
            r:puts( string.format("%s: %s\n", k, v) )
        end
    elseif r.method == 'POST' then
        r:puts("Hello Lua World!\n")
        for k, v in pairs( r:parsebody() ) do
            r:puts( string.format("%s: %s\n", k, v) )
        end
    elseif r.method == 'PUT' then
-- use our own Error contents
        r:puts("Unsupported HTTP method " .. r.method)
        r.status = 405
        return apache2.OK
    else
-- use the ErrorDocument
        return 501
    end
    return apache2.OK
end
</highlight>

<p>
This handler function just prints out the uri or form encoded
arguments to a plaintext page.
</p>

<p>
This means (and in fact encourages) that you can have multiple
handlers (or hooks, or filters) in the same script.
</p>

</section>

<section id="writingauthzproviders">
<title>Writing Authorization Providers</title>

<p><module>mod_authz_core</module> provides a high-level interface to
authorization that is much easier to use than using into the relevant
hooks directly. The first argument to the
<directive module="mod_authz_core">Require</directive> directive gives
the name of the responsible authorization provider. For any
<directive module="mod_authz_core">Require</directive> line,
<module>mod_authz_core</module> will call the authorization provider
of the given name, passing the rest of the line as parameters. The
provider will then check authorization and pass the result as return
value.</p>

<p>The authz provider is normally called before authentication. If it needs to
know the authenticated user name (or if the user will be authenticated at
all), the provider must return <code>apache2.AUTHZ_DENIED_NO_USER</code>.
This will cause authentication to proceed and the authz provider to be
called a second time.</p>

<p>The following authz provider function takes two arguments, one ip
address and one user name. It will allow access from the given ip address
without authentication, or if the authenticated user matches the second
argument:</p>

<highlight language="lua">
<strong>authz_provider.lua</strong><br/>

require 'apache2'

function authz_check_foo(r, ip, user)
    if r.useragent_ip == ip then
        return apache2.AUTHZ_GRANTED
    elseif r.user == nil then
        return apache2.AUTHZ_DENIED_NO_USER
    elseif r.user == user then
        return apache2.AUTHZ_GRANTED
    else
        return apache2.AUTHZ_DENIED
    end
end
</highlight>

<p>The following configuration registers this function as provider
<code>foo</code> and configures it for URL <code>/</code>:</p>
<highlight language="config">
LuaAuthzProvider foo authz_provider.lua authz_check_foo
&lt;Location "/"&gt;
  Require foo 10.1.2.3 john_doe
&lt;/Location&gt;
</highlight>

</section>

<section id="writinghooks"><title>Writing Hooks</title>

<p>Hook functions are how modules (and Lua scripts) participate in the
processing of requests. Each type of hook exposed by the server exists for
a specific purpose, such as mapping requests to the file system,
performing access control, or setting mime types:</p>

<table border="1" style="zebra">
    <tr>
        <th>Hook phase</th>
        <th>mod_lua directive</th>
        <th>Description</th>
    </tr>
    <tr>
        <td>Quick handler</td>
        <td><directive module="mod_lua">LuaQuickHandler</directive></td>
        <td>This is the first hook that will be called after a request has
            been mapped to a host or virtual host</td>
    </tr>
    <tr>
        <td>Pre-Translate name</td>
        <td><directive module="mod_lua">LuaHookPreTranslateName</directive></td>
        <td>This phase translates the requested URI into a filename on the
            system, before decoding occurs. Modules such as <module>mod_proxy</module>
            can operate in this phase.</td>
    </tr>
    <tr>
        <td>Translate name</td>
        <td><directive module="mod_lua">LuaHookTranslateName</directive></td>
        <td>This phase translates the requested URI into a filename on the
            system. Modules such as <module>mod_alias</module> and
            <module>mod_rewrite</module> operate in this phase.</td>
    </tr>
    <tr>
        <td>Map to storage</td>
        <td><directive module="mod_lua">LuaHookMapToStorage</directive></td>
        <td>This phase maps files to their physical, cached or external/proxied storage.
            It can be used by proxy or caching modules</td>
    </tr>
    <tr>
        <td>Check Access</td>
        <td><directive module="mod_lua">LuaHookAccessChecker</directive></td>
        <td>This phase checks whether a client has access to a resource. This
            phase is run before the user is authenticated, so beware.
        </td>
    </tr>
    <tr>
        <td>Check User ID</td>
        <td><directive module="mod_lua">LuaHookCheckUserID</directive></td>
        <td>This phase it used to check the negotiated user ID</td>
    </tr>
    <tr>
        <td>Check Authorization</td>
        <td><directive module="mod_lua">LuaHookAuthChecker</directive> or
            <directive module="mod_lua">LuaAuthzProvider</directive></td>
        <td>This phase authorizes a user based on the negotiated credentials, such as
            user ID, client certificate etc.
        </td>
    </tr>
    <tr>
        <td>Check Type</td>
        <td><directive module="mod_lua">LuaHookTypeChecker</directive></td>
        <td>This phase checks the requested file and assigns a content type and
            a handler to it</td>
    </tr>
    <tr>
        <td>Fixups</td>
        <td><directive module="mod_lua">LuaHookFixups</directive></td>
        <td>This is the final "fix anything" phase before the content handlers
            are run. Any last-minute changes to the request should be made here.</td>
    </tr>
    <tr>
        <td>Content handler</td>
        <td>fx. <code>.lua</code> files or through <directive module="mod_lua">LuaMapHandler</directive></td>
        <td>This is where the content is handled. Files are read, parsed, some are run,
            and the result is sent to the client</td>
    </tr>
    <tr>
        <td>Logging</td>
        <td><directive module="mod_lua">LuaHookLog</directive></td>
        <td>Once a request has been handled, it enters several logging phases,
            which logs the request in either the error or access log. Mod_lua
            is able to hook into the start of this and control logging output.</td>
    </tr>

</table>

<p>Hook functions are passed the request object as their only argument
(except for LuaAuthzProvider, which also gets passed the arguments from
the Require directive).
They can return any value, depending on the hook, but most commonly
they'll return OK, DONE, or DECLINED, which you can write in Lua as
<code>apache2.OK</code>, <code>apache2.DONE</code>, or
<code>apache2.DECLINED</code>, or else an HTTP status code.</p>


<highlight language="lua">
<strong>translate_name.lua</strong><br/>
-- example hook that rewrites the URI to a filesystem path.

require 'apache2'

function translate_name(r)
    if r.uri == "/translate-name" then
        r.filename = r.document_root .. "/find_me.txt"
        return apache2.OK
    end
    -- we don't care about this URL, give another module a chance
    return apache2.DECLINED
end
</highlight>


<highlight language="lua">
<strong>translate_name2.lua</strong><br/>
--[[ example hook that rewrites one URI to another URI. It returns a
     apache2.DECLINED to give other URL mappers a chance to work on the
     substitution, including the core translate_name hook which maps based
     on the DocumentRoot.

     Note: Use the early/late flags in the directive to make it run before
           or after mod_alias.
--]]

require 'apache2'

function translate_name(r)
    if r.uri == "/translate-name" then
        r.uri = "/find_me.txt"
        return apache2.DECLINED
    end
    return apache2.DECLINED
end
</highlight>
</section>

<section id="datastructures"><title>Data Structures</title>

<dl>
<dt>request_rec</dt>
        <dd>
        <p>The request_rec is mapped in as a userdata. It has a metatable
        which lets you do useful things with it. For the most part it
        has the same fields as the request_rec struct, many of which are writable as
        well as readable.  (The table fields' content can be changed, but the
        fields themselves cannot be set to different tables.)</p>

        <table border="1" style="zebra">

        <tr>
          <th><strong>Name</strong></th>
          <th><strong>Lua type</strong></th>
          <th><strong>Writable</strong></th>
          <th><strong>Description</strong></th>
        </tr>
        <tr>
          <td><code>allowoverrides</code></td>
          <td>string</td>
          <td>no</td>
          <td>The AllowOverride options applied to the current request.</td>
        </tr>
        <tr>
          <td><code>ap_auth_type</code></td>
          <td>string</td>
          <td>no</td>
          <td>If an authentication check was made, this is set to the type
          of authentication (f.x. <code>basic</code>)</td>
        </tr>
        <tr>
          <td><code>args</code></td>
          <td>string</td>
          <td>yes</td>
          <td>The query string arguments extracted from the request
            (f.x. <code>foo=bar&amp;name=johnsmith</code>)</td>
        </tr>
        <tr>
          <td><code>assbackwards</code></td>
          <td>boolean</td>
          <td>no</td>
          <td>Set to true if this is an HTTP/0.9 style request
            (e.g. <code>GET /foo</code> (with no headers) )</td>
        </tr>
        <tr>
          <td><code>auth_name</code></td>
          <td>string</td>
          <td>no</td>
          <td>The realm name used for authorization (if applicable).</td>
        </tr>
        <tr>
          <td><code>banner</code></td>
          <td>string</td>
          <td>no</td>
          <td>The server banner, f.x. <code>Apache HTTP Server/2.4.3 openssl/0.9.8c</code></td>
        </tr>
        <tr>
          <td><code>basic_auth_pw</code></td>
          <td>string</td>
          <td>no</td>
          <td>The basic auth password sent with this request, if any</td>
        </tr>
        <tr>
          <td><code>canonical_filename</code></td>
          <td>string</td>
          <td>no</td>
          <td>The canonical filename of the request</td>
        </tr>
        <tr>
          <td><code>content_encoding</code></td>
          <td>string</td>
          <td>no</td>
          <td>The content encoding of the current request</td>
        </tr>
        <tr>
          <td><code>content_type</code></td>
          <td>string</td>
          <td>yes</td>
          <td>The content type of the current request, as determined in the
            type_check phase (f.x. <code>image/gif</code> or <code>text/html</code>)</td>
        </tr>
        <tr>
          <td><code>context_prefix</code></td>
          <td>string</td>
          <td>no</td>
          <td></td>
        </tr>
        <tr>
          <td><code>context_document_root</code></td>
          <td>string</td>
          <td>no</td>
          <td></td>
        </tr>

        <tr>
          <td><code>document_root</code></td>
          <td>string</td>
          <td>no</td>
          <td>The document root of the host</td>
        </tr>
        <tr>
          <td><code>err_headers_out</code></td>
          <td>table</td>
          <td>no</td>
          <td>MIME header environment for the response, printed even on errors and
            persist across internal redirects.  A read-only lua table suitable for iteration is available as r:err_headers_out_table().</td>
        </tr>
        <tr>
          <td><code>filename</code></td>
          <td>string</td>
          <td>yes</td>
          <td>The file name that the request maps to, f.x. /www/example.com/foo.txt. This can be
            changed in the pre-translate-name, translate-name or map-to-storage phases of a request to allow the
            default handler (or script handlers) to serve a different file than what was requested.</td>
        </tr>
        <tr>
          <td><code>handler</code></td>
          <td>string</td>
          <td>yes</td>
          <td>The name of the <a href="../handler.html">handler</a> that should serve this request, f.x.
            <code>lua-script</code> if it is to be served by mod_lua. This is typically set by the
            <directive module="mod_mime">AddHandler</directive> or <directive module="core">SetHandler</directive>
            directives, but could also be set via mod_lua to allow another handler to serve up a specific request
            that would otherwise not be served by it.
            </td>
        </tr>

        <tr>
          <td><code>headers_in</code></td>
          <td>table</td>
          <td>yes</td>
          <td>MIME header environment from the request. This contains headers such as <code>Host,
            User-Agent, Referer</code> and so on. A read-only lua table suitable for iteration is available as r:headers_in_table().</td>
        </tr>
        <tr>
          <td><code>headers_out</code></td>
          <td>table</td>
          <td>yes</td>
          <td>MIME header environment for the response. A read-only lua table suitable for iteration is available as r:headers_out_table().</td>
        </tr>
        <tr>
          <td><code>hostname</code></td>
          <td>string</td>
          <td>no</td>
          <td>The host name, as set by the <code>Host:</code> header or by a full URI.</td>
        </tr>
        <tr>
          <td><code>is_https</code></td>
          <td>boolean</td>
          <td>no</td>
          <td>Whether or not this request is done via HTTPS</td>
        </tr>
        <tr>
          <td><code>is_initial_req</code></td>
          <td>boolean</td>
          <td>no</td>
          <td>Whether this request is the initial request or a sub-request</td>
        </tr>
        <tr>
          <td><code>limit_req_body</code></td>
          <td>number</td>
          <td>no</td>
          <td>The size limit of the request body for this request, or 0 if no limit.</td>
        </tr>
        <tr>
          <td><code>log_id</code></td>
          <td>string</td>
          <td>no</td>
          <td>The ID to identify request in access and error log.</td>
        </tr>
        <tr>
          <td><code>method</code></td>
          <td>string</td>
          <td>no</td>
          <td>The request method, f.x. <code>GET</code> or <code>POST</code>.</td>
        </tr>
        <tr>
          <td><code>notes</code></td>
          <td>table</td>
          <td>yes</td>
          <td>A list of notes that can be passed on from one module to another.  A read-only lua table suitable for iteration is available as r:notes_table().</td>
        </tr>
        <tr>
          <td><code>options</code></td>
          <td>string</td>
          <td>no</td>
          <td>The Options directive applied to the current request.</td>
        </tr>
        <tr>
          <td><code>path_info</code></td>
          <td>string</td>
          <td>no</td>
          <td>The PATH_INFO extracted from this request.</td>
        </tr>
        <tr>
          <td><code>port</code></td>
          <td>number</td>
          <td>no</td>
          <td>The server port used by the request.</td>
        </tr>
        <tr>
          <td><code>protocol</code></td>
          <td>string</td>
          <td>no</td>
          <td>The protocol used, f.x. <code>HTTP/1.1</code></td>
        </tr>
        <tr>
          <td><code>proxyreq</code></td>
          <td>string</td>
          <td>yes</td>
          <td>Denotes whether this is a proxy request or not. This value is generally set in
              the post_read_request/pre_translate_name/translate_name phase of a request.</td>
        </tr>
        <tr>
          <td><code>range</code></td>
          <td>string</td>
          <td>no</td>
          <td>The contents of the <code>Range:</code> header.</td>
        </tr>
        <tr>
          <td><code>remaining</code></td>
          <td>number</td>
          <td>no</td>
          <td>The number of bytes remaining to be read from the request body.</td>
        </tr>
        <tr>
          <td><code>server_built</code></td>
          <td>string</td>
          <td>no</td>
          <td>The time the server executable was built.</td>
        </tr>
        <tr>
          <td><code>server_name</code></td>
          <td>string</td>
          <td>no</td>
          <td>The server name for this request.</td>
        </tr>
        <tr>
          <td><code>some_auth_required</code></td>
          <td>boolean</td>
          <td>no</td>
          <td>Whether some authorization is/was required for this request.</td>
        </tr>
        <tr>
          <td><code>subprocess_env</code></td>
          <td>table</td>
          <td>yes</td>
          <td>The environment variables set for this request. A read-only lua table suitable for iteration is available as r:subprocess_env_table().</td>
        </tr>
        <tr>
          <td><code>started</code></td>
          <td>number</td>
          <td>no</td>
          <td>The time the server was (re)started, in seconds since the epoch (Jan 1st, 1970)</td>
        </tr>
        <tr>
          <td><code>status</code></td>
          <td>number</td>
          <td>yes</td>
          <td>The (current) HTTP return code for this request, f.x. <code>200</code> or <code>404</code>.</td>
        </tr>
        <tr>
          <td><code>the_request</code></td>
          <td>string</td>
          <td>no</td>
          <td>The request string as sent by the client, f.x. <code>GET /foo/bar HTTP/1.1</code>.</td>
        </tr>
        <tr>
          <td><code>unparsed_uri</code></td>
          <td>string</td>
          <td>no</td>
          <td>The unparsed URI of the request</td>
        </tr>
        <tr>
          <td><code>uri</code></td>
          <td>string</td>
          <td>yes</td>
          <td>The URI after it has been parsed by httpd</td>
        </tr>
        <tr>
          <td><code>user</code></td>
          <td>string</td>
          <td>yes</td>
          <td>If an authentication check has been made, this is set to the name of the authenticated user.</td>
        </tr>
        <tr>
          <td><code>useragent_ip</code></td>
          <td>string</td>
          <td>no</td>
          <td>The IP of the user agent making the request</td>
        </tr>
        </table>
           </dd>
    </dl>
</section>
<section id="functions"><title>Built in functions</title>

<p>The request_rec object has (at least) the following methods:</p>

<highlight language="lua">
r:flush()   -- flushes the output buffer.
            -- Returns true if the flush was successful, false otherwise.

while we_have_stuff_to_send do
    r:puts("Bla bla bla\n") -- print something to client
    r:flush() -- flush the buffer (send to client)
    r.usleep(500000) -- fake processing time for 0.5 sec. and repeat
end
</highlight>

<highlight language="lua">
r:add_output_filter(filter_name) -- add an output filter:

r:add_output_filter("fooFilter") -- add the fooFilter to the output stream
</highlight>

<highlight language="lua">
r:sendfile(filename) -- sends an entire file to the client, using sendfile if supported by the current platform:

if use_sendfile_thing then
    r:sendfile("/var/www/large_file.img")
end
</highlight>

<highlight language="lua">
r:parseargs() -- returns two tables; one standard key/value table for regular GET data,
              -- and one for multi-value data (fx. foo=1&amp;foo=2&amp;foo=3):

local GET, GETMULTI = r:parseargs()
r:puts("Your name is: " .. GET['name'] or "Unknown")
</highlight>

<highlight language="lua">
r:parsebody([sizeLimit]) -- parse the request body as a POST and return two lua tables,
                         -- just like r:parseargs().
                         -- An optional number may be passed to specify the maximum number
                         -- of bytes to parse. Default is 8192 bytes:

local POST, POSTMULTI = r:parsebody(1024*1024)
r:puts("Your name is: " .. POST['name'] or "Unknown")
</highlight>

<highlight language="lua">
r:puts("hello", " world", "!") -- print to response body, self explanatory
</highlight>

<highlight language="lua">
r:write("a single string") -- print to response body, self explanatory
</highlight>

<highlight language="lua">
r:escape_html("&lt;html&gt;test&lt;/html&gt;") -- Escapes HTML code and returns the escaped result
</highlight>

<highlight language="lua">
r:base64_encode(string) -- Encodes a string using the Base64 encoding standard:

local encoded = r:base64_encode("This is a test") -- returns VGhpcyBpcyBhIHRlc3Q=
</highlight>

<highlight language="lua">
r:base64_decode(string) -- Decodes a Base64-encoded string:

local decoded = r:base64_decode("VGhpcyBpcyBhIHRlc3Q=") -- returns 'This is a test'
</highlight>

<highlight language="lua">
r:md5(string) -- Calculates and returns the MD5 digest of a string (binary safe):

local hash = r:md5("This is a test") -- returns ce114e4501d2f4e2dcea3e17b546f339
</highlight>

<highlight language="lua">
r:sha1(string) -- Calculates and returns the SHA1 digest of a string (binary safe):

local hash = r:sha1("This is a test") -- returns a54d88e06612d820bc3be72877c74f257b561b19
</highlight>

<highlight language="lua">
r:escape(string) -- URL-Escapes a string:

local url = "http://foo.bar/1 2 3 &amp; 4 + 5"
local escaped = r:escape(url) -- returns 'http%3a%2f%2ffoo.bar%2f1+2+3+%26+4+%2b+5'
</highlight>

<highlight language="lua">
r:unescape(string) -- Unescapes an URL-escaped string:

local url = "http%3a%2f%2ffoo.bar%2f1+2+3+%26+4+%2b+5"
local unescaped = r:unescape(url) -- returns 'http://foo.bar/1 2 3 &amp; 4 + 5'
</highlight>

<highlight language="lua">
r:construct_url(string) -- Constructs an URL from an URI

local url = r:construct_url(r.uri)
</highlight>

<highlight language="lua">
r.mpm_query(number) -- Queries the server for MPM information using ap_mpm_query:

local mpm = r.mpm_query(14)
if mpm == 1 then
    r:puts("This server uses the Event MPM")
end
</highlight>

<highlight language="lua">
r:expr(string) -- Evaluates an <a href="../expr.html">expr</a> string.

if r:expr("%{HTTP_HOST} =~ /^www/") then
    r:puts("This host name starts with www")
end
</highlight>

<highlight language="lua">
r:scoreboard_process(a) -- Queries the server for information about the process at position <code>a</code>:

local process = r:scoreboard_process(1)
r:puts("Server 1 has PID " .. process.pid)
</highlight>

<highlight language="lua">
r:scoreboard_worker(a, b) -- Queries for information about the worker thread, <code>b</code>, in process <code>a</code>:

local thread = r:scoreboard_worker(1, 1)
r:puts("Server 1's thread 1 has thread ID " .. thread.tid .. " and is in " .. thread.status .. " status")
</highlight>


<highlight language="lua">
r:clock() -- Returns the current time with microsecond precision
</highlight>

<highlight language="lua">
r:requestbody(filename) -- Reads and returns the request body of a request.
                -- If 'filename' is specified, it instead saves the
                -- contents to that file:

local input = r:requestbody()
r:puts("You sent the following request body to me:\n")
r:puts(input)
</highlight>

<highlight language="lua">
r:add_input_filter(filter_name) -- Adds 'filter_name' as an input filter
</highlight>

<highlight language="lua">
r.module_info(module_name) -- Queries the server for information about a module

local mod = r.module_info("mod_lua.c")
if mod then
    for k, v in pairs(mod.commands) do
       r:puts( ("%s: %s\n"):format(k,v)) -- print out all directives accepted by this module
    end
end
</highlight>

<highlight language="lua">
r:loaded_modules() -- Returns a list of modules loaded by httpd:

for k, module in pairs(r:loaded_modules()) do
    r:puts("I have loaded module " .. module .. "\n")
end
</highlight>

<highlight language="lua">
r:runtime_dir_relative(filename) -- Compute the name of a run-time file (e.g., shared memory "file")
                         -- relative to the appropriate run-time directory.
</highlight>

<highlight language="lua">
r:server_info() -- Returns a table containing server information, such as
                -- the name of the httpd executable file, mpm used etc.
</highlight>

<highlight language="lua">
r:set_document_root(file_path) -- Sets the document root for the request to file_path
</highlight>

<!--
<highlight language="lua">
r:add_version_component(component_string) - - Adds a component to the server banner.
</highlight>
-->

<highlight language="lua">
r:set_context_info(prefix, docroot) -- Sets the context prefix and context document root for a request
</highlight>

<highlight language="lua">
r:os_escape_path(file_path) -- Converts an OS path to a URL in an OS dependent way
</highlight>

<highlight language="lua">
r:escape_logitem(string) -- Escapes a string for logging
</highlight>

<highlight language="lua">
r.strcmp_match(string, pattern) -- Checks if 'string' matches 'pattern' using strcmp_match (globs).
                        -- fx. whether 'www.example.com' matches '*.example.com':

local match = r.strcmp_match("foobar.com", "foo*.com")
if match then
    r:puts("foobar.com matches foo*.com")
end
</highlight>

<highlight language="lua">
r:set_keepalive() -- Sets the keepalive status for a request. Returns true if possible, false otherwise.
</highlight>

<highlight language="lua">
r:make_etag() -- Constructs and returns the etag for the current request.
</highlight>

<highlight language="lua">
r:send_interim_response(clear) -- Sends an interim (1xx) response to the client.
                       -- if 'clear' is true, available headers will be sent and cleared.
</highlight>

<highlight language="lua">
r:custom_response(status_code, string) -- Construct and set a custom response for a given status code.
                               -- This works much like the ErrorDocument directive:

r:custom_response(404, "Baleted!")
</highlight>

<highlight language="lua">
r.exists_config_define(string) -- Checks whether a configuration definition exists or not:

if r.exists_config_define("FOO") then
    r:puts("httpd was probably run with -DFOO, or it was defined in the configuration")
end
</highlight>

<highlight language="lua">
r:state_query(string) -- Queries the server for state information
</highlight>

<highlight language="lua">
r:stat(filename [,wanted]) -- Runs stat() on a file, and returns a table with file information:

local info = r:stat("/var/www/foo.txt")
if info then
    r:puts("This file exists and was last modified at: " .. info.modified)
end
</highlight>

<highlight language="lua">
r:regex(string, pattern [,flags]) -- Runs a regular expression match on a string, returning captures if matched:

local matches = r:regex("foo bar baz", [[foo (\w+) (\S*)]])
if matches then
    r:puts("The regex matched, and the last word captured ($2) was: " .. matches[2])
end

-- Example ignoring case sensitivity:
local matches = r:regex("FOO bar BAz", [[(foo) bar]], 1)

-- Flags can be a bitwise combination of:
-- 0x01: Ignore case
-- 0x02: Multiline search
</highlight>

<highlight language="lua">
r.usleep(number_of_microseconds) -- Puts the script to sleep for a given number of microseconds.
</highlight>

<highlight language="lua">
r:dbacquire(dbType[, dbParams]) -- Acquires a connection to a database and returns a database class.
                        -- See '<a href="#databases">Database connectivity</a>' for details.
</highlight>

<highlight language="lua">
r:ivm_set("key", value) -- Set an Inter-VM variable to hold a specific value.
                        -- These values persist even though the VM is gone or not being used,
                        -- and so should only be used if MaxConnectionsPerChild is > 0
                        -- Values can be numbers, strings and booleans, and are stored on a
                        -- per process basis (so they won't do much good with a prefork mpm)

r:ivm_get("key")        -- Fetches a variable set by ivm_set. Returns the contents of the variable
                        -- if it exists or nil if no such variable exists.

-- An example getter/setter that saves a global variable outside the VM:
function handle(r)
    -- First VM to call this will get no value, and will have to create it
    local foo = r:ivm_get("cached_data")
    if not foo then
        foo = do_some_calcs() -- fake some return value
        r:ivm_set("cached_data", foo) -- set it globally
    end
    r:puts("Cached data is: ", foo)
end
</highlight>

<highlight language="lua">
r:htpassword(string [,algorithm [,cost]]) -- Creates a password hash from a string.
                                          -- algorithm: 0 = APMD5 (default), 1 = SHA, 2 = BCRYPT, 3 = CRYPT.
                                          -- cost: only valid with BCRYPT algorithm (default = 5).
</highlight>

<highlight language="lua">
r:mkdir(dir [,mode]) -- Creates a directory and sets mode to optional mode parameter.
</highlight>

<highlight language="lua">
r:mkrdir(dir [,mode]) -- Creates directories recursive and sets mode to optional mode parameter.
</highlight>

<highlight language="lua">
r:rmdir(dir) -- Removes a directory.
</highlight>

<highlight language="lua">
r:touch(file [,mtime]) -- Sets the file modification time to current time or to optional mtime msec value.
</highlight>

<highlight language="lua">
r:get_direntries(dir) -- Returns a table with all directory entries.

function handle(r)
  local dir = r.context_document_root
  for _, f in ipairs(r:get_direntries(dir)) do
    local info = r:stat(dir .. "/" .. f)
    if info then
      local mtime = os.date(fmt, info.mtime / 1000000)
      local ftype = (info.filetype == 2) and "[dir] " or "[file]"
      r:puts( ("%s %s %10i %s\n"):format(ftype, mtime, info.size, f) )
    end
  end
end
</highlight>

<highlight language="lua">
r.date_parse_rfc(string) -- Parses a date/time string and returns seconds since epoche.
</highlight>

<highlight language="lua">
r:getcookie(key) -- Gets a HTTP cookie
</highlight>

<highlight language="lua">
r:setcookie{
  key = [key],
  value = [value],
  expires = [expiry],
  secure = [boolean],
  httponly = [boolean],
  path = [path],
  domain = [domain]
} -- Sets a HTTP cookie, for instance:

r:setcookie{
  key = "cookie1",
  value = "HDHfa9eyffh396rt",
  expires = os.time() + 86400,
  secure = true
}
</highlight>

<highlight language="lua">
r:wsupgrade() -- Upgrades a connection to WebSockets if possible (and requested):
if r:wsupgrade() then -- if we can upgrade:
    r:wswrite("Welcome to websockets!") -- write something to the client
    r:wsclose()  -- goodbye!
end
</highlight>

<highlight language="lua">
r:wsread() -- Reads a WebSocket frame from a WebSocket upgraded connection (see above):

local line, isFinal = r:wsread() -- isFinal denotes whether this is the final frame.
                                 -- If it isn't, then more frames can be read
r:wswrite("You wrote: " .. line)
</highlight>

<highlight language="lua">
r:wswrite(line) -- Writes a frame to a WebSocket client:
r:wswrite("Hello, world!")
</highlight>

<highlight language="lua">
r:wsclose() -- Closes a WebSocket request and terminates it for httpd:

if r:wsupgrade() then
    r:wswrite("Write something: ")
    local line = r:wsread() or "nothing"
    r:wswrite("You wrote: " .. line);
    r:wswrite("Goodbye!")
    r:wsclose()
end
</highlight>

<highlight language="lua">
r:wspeek() -- Checks if any data is ready to be read

-- Sleep while nothing is being sent to us...
while r:wspeek() == false do
   r.usleep(50000)
end
-- We have data ready!
local line = r:wsread()

</highlight>


<highlight language="lua">
r:config() -- Get a walkable tree of the entire httpd configuration
</highlight>

<highlight language="lua">
r:activeconfig() -- Get a walkable tree of the active (virtualhost-specific) httpd configuration
</highlight>


</section>

<section id="logging"><title>Logging Functions</title>

<highlight language="lua">
-- examples of logging messages
r:trace1("This is a trace log message") -- trace1 through trace8 can be used
r:debug("This is a debug log message")
r:info("This is an info log message")
r:notice("This is a notice log message")
r:warn("This is a warn log message")
r:err("This is an err log message")
r:alert("This is an alert log message")
r:crit("This is a crit log message")
r:emerg("This is an emerg log message")
</highlight>

</section>

<section id="apache2"><title>apache2 Package</title>
<p>A package named <code>apache2</code> is available with (at least) the following contents.</p>
<dl>
  <dt>apache2.OK</dt>
  <dd>internal constant OK.  Handlers should return this if they've
  handled the request.</dd>
  <dt>apache2.DECLINED</dt>
  <dd>internal constant DECLINED.  Handlers should return this if
  they are not going to handle the request.</dd>
  <dt>apache2.DONE</dt>
  <dd>internal constant DONE.</dd>
  <dt>apache2.version</dt>
  <dd>Apache HTTP server version string</dd>
  <dt>apache2.HTTP_MOVED_TEMPORARILY</dt>
  <dd>HTTP status code</dd>
  <dt>apache2.PROXYREQ_NONE, apache2.PROXYREQ_PROXY, apache2.PROXYREQ_REVERSE, apache2.PROXYREQ_RESPONSE</dt>
  <dd>internal constants used by <module>mod_proxy</module></dd>
  <dt>apache2.AUTHZ_DENIED, apache2.AUTHZ_GRANTED, apache2.AUTHZ_NEUTRAL, apache2.AUTHZ_GENERAL_ERROR, apache2.AUTHZ_DENIED_NO_USER</dt>
  <dd>internal constants used by <module>mod_authz_core</module></dd>

</dl>
<p>(Other HTTP status codes are not yet implemented.)</p>
</section>

<section id="modifying_buckets">
    <title>Modifying contents with Lua filters</title>
    <p>
    Filter functions implemented via <directive module="mod_lua">LuaInputFilter</directive>
    or <directive module="mod_lua">LuaOutputFilter</directive> are designed as
    three-stage non-blocking functions using coroutines to suspend and resume a
    function as buckets are sent down the filter chain. The core structure of
    such a function is:
    </p>
    <highlight language="lua">
function filter(r)
    -- Our first yield is to signal that we are ready to receive buckets.
    -- Before this yield, we can set up our environment, check for conditions,
    -- and, if we deem it necessary, decline filtering a request altogether:
    if something_bad then
        return -- This would skip this filter.
    end
    -- Regardless of whether we have data to prepend, a yield MUST be called here.
    -- Note that only output filters can prepend data. Input filters must use the
    -- final stage to append data to the content.
    coroutine.yield([optional header to be prepended to the content])

    -- After we have yielded, buckets will be sent to us, one by one, and we can
    -- do whatever we want with them and then pass on the result.
    -- Buckets are stored in the global variable 'bucket', so we create a loop
    -- that checks if 'bucket' is not nil:
    while bucket ~= nil do
        local output = mangle(bucket) -- Do some stuff to the content
        coroutine.yield(output) -- Return our new content to the filter chain
    end

    -- Once the buckets are gone, 'bucket' is set to nil, which will exit the
    -- loop and land us here. Anything extra we want to append to the content
    -- can be done by doing a final yield here. Both input and output filters
    -- can append data to the content in this phase.
    coroutine.yield([optional footer to be appended to the content])
end
    </highlight>
</section>

<section id="databases">
    <title>Database connectivity</title>
    <p>
    Mod_lua implements a simple database feature for querying and running commands
    on the most popular database engines (mySQL, PostgreSQL, FreeTDS, ODBC, SQLite, Oracle)
    as well as mod_dbd.</p>
    <p>
    The <code>dbType</code> to use as the first parameter of <code>dbacquire</code>
    is case sensitive.</p>
    <p>
    It should be one of <code>mysql</code>, <code>pgsql</code>, <code>freetds</code>,
    <code>odbc</code>, <code>sqlite2</code>, <code>sqlite3</code>, <code>oracle</code>
    or <code>mod_dbd</code>.
    </p>
    <p>The example below shows how to acquire a database handle and return information from a table:</p>
    <highlight language="lua">
function handle(r)
    -- Acquire a database handle
    local database, err = r:dbacquire("mysql", "server=localhost,user=someuser,pass=somepass,dbname=mydb")
    if not err then
        -- Select some information from it
        local results, err = database:select(r, "SELECT `name`, `age` FROM `people` WHERE 1")
        if not err then
            local rows = results(0) -- fetch all rows synchronously
            for k, row in pairs(rows) do
                r:puts( string.format("Name: %s, Age: %s&lt;br/&gt;", row[1], row[2]) )
            end
        else
            r:puts("Database query error: " .. err)
        end
        database:close()
    else
        r:puts("Could not connect to the database: " .. err)
    end
end
    </highlight>
    <p>
    To utilize <module>mod_dbd</module>, specify <code>mod_dbd</code>
    as the database type, or leave the field blank:
    </p>
    <highlight language="lua">
    local database = r:dbacquire("mod_dbd")
    </highlight>
    <section id="database_object">
        <title>Database object and contained functions</title>
        <p>The database object returned by <code>dbacquire</code> has the following methods:</p>
        <p><strong>Normal select and query from a database:</strong></p>
    <highlight language="lua">
-- Run a statement and return the number of rows affected:
local affected, errmsg = database:query(r, "DELETE FROM `tbl` WHERE 1")

-- Run a statement and return a result set that can be used synchronously or async:
local result, errmsg = database:select(r, "SELECT * FROM `people` WHERE 1")
    </highlight>
        <p><strong>Using prepared statements (recommended):</strong></p>
    <highlight language="lua">
-- Create and run a prepared statement:
local statement, errmsg = database:prepare(r, "DELETE FROM `tbl` WHERE `age` > %u")
if not errmsg then
    local result, errmsg = statement:query(20) -- run the statement with age &gt; 20
end

-- Fetch a prepared statement from a DBDPrepareSQL directive:
local statement, errmsg = database:prepared(r, "someTag")
if not errmsg then
    local result, errmsg = statement:select("John Doe", 123) -- inject the values "John Doe" and 123 into the statement
end

</highlight>
        <p><strong>Escaping values, closing databases etc:</strong></p>
    <highlight language="lua">
-- Escape a value for use in a statement:
local escaped = database:escape(r, [["'|blabla]])

-- Close a database connection and free up handles:
database:close()

-- Check whether a database connection is up and running:
local connected = database:active()
    </highlight>
    </section>
    <section id="result_sets">
    <title>Working with result sets</title>
    <p>The result set returned by <code>db:select</code> or by the prepared statement functions
    created through <code>db:prepare</code> can be used to
    fetch rows synchronously or asynchronously, depending on the row number specified:<br/>
    <code>result(0)</code> fetches all rows in a synchronous manner, returning a table of rows.<br/>
    <code>result(-1)</code> fetches the next available row in the set, asynchronously.<br/>
    <code>result(N)</code> fetches row number <code>N</code>, asynchronously:
    </p>
    <highlight language="lua">
-- fetch a result set using a regular query:
local result, err = db:select(r, "SELECT * FROM `tbl` WHERE 1")

local rows = result(0) -- Fetch ALL rows synchronously
local row = result(-1) -- Fetch the next available row, asynchronously
local row = result(1234) -- Fetch row number 1234, asynchronously
local row = result(-1, true) -- Fetch the next available row, using row names as key indexes.
    </highlight>
    <p>One can construct a function that returns an iterative function to iterate over all rows
    in a synchronous or asynchronous way, depending on the async argument:
    </p>
    <highlight language="lua">
function rows(resultset, async)
    local a = 0
    local function getnext()
        a = a + 1
        local row = resultset(-1)
        return row and a or nil, row
    end
    if not async then
        return pairs(resultset(0))
    else
        return getnext, self
    end
end

local statement, err = db:prepare(r, "SELECT * FROM `tbl` WHERE `age` > %u")
if not err then
     -- fetch rows asynchronously:
    local result, err = statement:select(20)
    if not err then
        for index, row in rows(result, true) do
            ....
        end
    end

     -- fetch rows synchronously:
    local result, err = statement:select(20)
    if not err then
        for index, row in rows(result, false) do
            ....
        end
    end
end
    </highlight>
    </section>
    <section id="closing_databases">
        <title>Closing a database connection</title>

    <p>Database handles should be closed using <code>database:close()</code> when they are no longer
    needed. If you do not close them manually, they will eventually be garbage collected and
    closed by mod_lua, but you may end up having too many unused connections to the database
    if you leave the closing up to mod_lua. Essentially, the following two measures are
    the same:
    </p>
    <highlight language="lua">
-- Method 1: Manually close a handle
local database = r:dbacquire("mod_dbd")
database:close() -- All done

-- Method 2: Letting the garbage collector close it
local database = r:dbacquire("mod_dbd")
database = nil -- throw away the reference
collectgarbage() -- close the handle via GC
</highlight>
    </section>
    <section id="database_caveat">
    <title>Precautions when working with databases</title>
    <p>Although the standard <code>query</code> and <code>run</code> functions are freely
    available, it is recommended that you use prepared statements whenever possible, to
    both optimize performance (if your db handle lives on for a long time) and to minimize
    the risk of SQL injection attacks. <code>run</code> and <code>query</code> should only
    be used when there are no variables inserted into a statement (a static statement).
    When using dynamic statements, use <code>db:prepare</code> or <code>db:prepared</code>.
    </p>
    </section>

</section>

<directivesynopsis>
<name>LuaRoot</name>
<description>Specify the base path for resolving relative paths for mod_lua directives</description>
<syntax>LuaRoot /path/to/a/directory</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>

<usage>
    <p>Specify the base path which will be used to evaluate all
    relative paths within mod_lua. If not specified they
    will be resolved relative to the current working directory,
    which may not always work well for a server.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaScope</name>
<description>One of once, request, conn, thread -- default is once</description>
<syntax>LuaScope once|request|conn|thread|server [min] [max]</syntax>
<default>LuaScope once</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>

<usage>
    <p>Specify the life cycle scope of the Lua interpreter which will
    be used by handlers in this "Directory." The default is "once"</p>

   <dl>
    <dt>once:</dt> <dd>use the interpreter once and throw it away.</dd>

    <dt>request:</dt> <dd>use the interpreter to handle anything based on
             the same file within this request, which is also
             request scoped.</dd>

    <dt>conn:</dt> <dd>Same as request but attached to the connection_rec</dd>

    <dt>thread:</dt> <dd>Use the interpreter for the lifetime of the thread
            handling the request (only available with threaded MPMs).</dd>

    <dt>server:</dt>  <dd>This one is different than others because the
            server scope is quite long lived, and multiple threads
            will have the same server_rec. To accommodate this,
            server scoped Lua states are stored in an apr
            resource list. The <code>min</code> and <code>max</code> arguments
            specify the minimum and maximum number of Lua states to keep in the
            pool.</dd>
   </dl>
    <p>
    Generally speaking, the <code>thread</code> and <code>server</code> scopes
    execute roughly 2-3 times faster than the rest, because they don't have to
    spawn new Lua states on every request (especially with the event MPM, as
    even keepalive requests will use a new thread for each request). If you are
    satisfied that your scripts will not have problems reusing a state, then
    the <code>thread</code> or <code>server</code> scopes should be used for
    maximum performance. While the <code>thread</code> scope will provide the
    fastest responses, the <code>server</code> scope will use less memory, as
    states are pooled, allowing f.x. 1000 threads to share only 100 Lua states,
    thus using only 10% of the memory required by the <code>thread</code> scope.
    </p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaMapHandler</name>
<description>Map a path to a lua handler</description>
<syntax>LuaMapHandler uri-pattern /path/to/lua/script.lua [function-name]</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
<usage>
    <p>This directive matches a uri pattern to invoke a specific
    handler function in a specific file. It uses PCRE regular
    expressions to match the uri, and supports interpolating
    match groups into both the file path and the function name.
    Be careful writing your regular expressions to avoid security
    issues.</p>
   <example><title>Examples:</title>
   <highlight language="config">
    LuaMapHandler /(\w+)/(\w+) /scripts/$1.lua handle_$2
    </highlight>
   </example>
        <p>This would match uri's such as /photos/show?id=9
        to the file /scripts/photos.lua and invoke the
        handler function handle_show on the lua vm after
        loading that file.</p>

<highlight language="config">
    LuaMapHandler /bingo /scripts/wombat.lua
</highlight>
        <p>This would invoke the "handle" function, which
        is the default if no specific function name is
        provided.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaPackagePath</name>
<description>Add a directory to lua's package.path</description>
<syntax>LuaPackagePath /path/to/include/?.lua</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
    <usage><p>Add a path to lua's module search path. Follows the same
    conventions as lua. This just munges the package.path in the
    lua vms.</p>

    <example><title>Examples:</title>
    <highlight language="config">
LuaPackagePath /scripts/lib/?.lua
LuaPackagePath /scripts/lib/?/init.lua
    </highlight>
    </example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaPackageCPath</name>
<description>Add a directory to lua's package.cpath</description>
<syntax>LuaPackageCPath /path/to/include/?.soa</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>

<usage>
    <p>Add a path to lua's shared library search path. Follows the same
    conventions as lua. This just munges the package.cpath in the
    lua vms.</p>

</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaCodeCache</name>
<description>Configure the compiled code cache.</description>
<syntax>LuaCodeCache stat|forever|never</syntax>
<default>LuaCodeCache stat</default>
<contextlist>
<context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>

<usage><p>
    Specify the behavior of the in-memory code cache. The default
    is stat, which stats the top level script (not any included
    ones) each time that file is needed, and reloads it if the
    modified time indicates it is newer than the one it has
    already loaded. The other values cause it to keep the file
    cached forever (don't stat and replace) or to never cache the
    file.</p>

    <p>In general stat or forever is good for production, and stat or never
    for development.</p>

    <example><title>Examples:</title>
    <highlight language="config">
LuaCodeCache stat
LuaCodeCache forever
LuaCodeCache never
    </highlight>
    </example>

</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaHookTranslateName</name>
<description>Provide a hook for the translate name phase of request processing</description>
<syntax>LuaHookTranslateName  /path/to/lua/script.lua  hook_function_name [early|late]</syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>
<override>All</override>
<compatibility>The optional third argument is supported in 2.3.15 and later</compatibility>

<usage><p>
    Add a hook (at APR_HOOK_MIDDLE) to the translate name phase of
    request processing. The hook function receives a single
    argument, the request_rec, and should return a status code,
    which is either an HTTP error code, or the constants defined
    in the apache2 module: apache2.OK, apache2.DECLINED, or
    apache2.DONE. </p>

    <p>For those new to hooks, basically each hook will be invoked
    until one of them returns apache2.OK. If your hook doesn't
    want to do the translation it should just return
    apache2.DECLINED. If the request should stop processing, then
    return apache2.DONE.</p>

    <p>Example:</p>

<highlight language="config">
# httpd.conf
LuaHookTranslateName /scripts/conf/hooks.lua silly_mapper
</highlight>

<highlight language="lua">
-- /scripts/conf/hooks.lua --
require "apache2"
function silly_mapper(r)
    if r.uri == "/" then
        r.filename = "/var/www/home.lua"
        return apache2.OK
    else
        return apache2.DECLINED
    end
end
</highlight>

   <note><title>Context</title><p>This directive is not valid in <directive
   type="section" module="core">Directory</directive>, <directive
   type="section" module="core">Files</directive>, or htaccess
   context.</p></note>

   <note><title>Ordering</title><p>The optional arguments "early" or "late"
   control when this script runs relative to other modules.</p></note>

</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaHookPreTranslate</name>
<description>Provide a hook for the pre_translate phase of a request
processing</description>
<syntax>LuaHookPreTranslate  /path/to/lua/script.lua hook_function_name</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
<usage>
<p>
    Just like LuaHookTranslateName, but executed at the pre_translate phase,
    where the URI-path is not percent decoded.
</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaHookFixups</name>
<description>Provide a hook for the fixups phase of a request
processing</description>
<syntax>LuaHookFixups  /path/to/lua/script.lua hook_function_name</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
<usage>
<p>
    Just like LuaHookTranslateName, but executed at the fixups phase
</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaHookLog</name>
<description>Provide a hook for the access log phase of a request
processing</description>
<syntax>LuaHookLog  /path/to/lua/script.lua log_function_name</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
<usage>
<p>
    This simple logging hook allows you to run a function when httpd enters the
    logging phase of a request. With it, you can append data to your own logs,
    manipulate data before the regular log is written, or prevent a log entry
    from being created. To prevent the usual logging from happening, simply return
    <code>apache2.DONE</code> in your logging handler, otherwise return
    <code>apache2.OK</code> to tell httpd to log as normal.
</p>
<p>Example:</p>
<highlight language="config">
LuaHookLog /path/to/script.lua logger
</highlight>
<highlight language="lua">
-- /path/to/script.lua --
function logger(r)
    -- flip a coin:
    -- If 1, then we write to our own Lua log and tell httpd not to log
    -- in the main log.
    -- If 2, then we just sanitize the output a bit and tell httpd to
    -- log the sanitized bits.

    if math.random(1,2) == 1 then
        -- Log stuff ourselves and don't log in the regular log
        local f = io.open("/foo/secret.log", "a")
        if f then
            f:write("Something secret happened at " .. r.uri .. "\n")
            f:close()
        end
        return apache2.DONE -- Tell httpd not to use the regular logging functions
    else
        r.uri = r.uri:gsub("somesecretstuff", "") -- sanitize the URI
        return apache2.OK -- tell httpd to log it.
    end
end
</highlight>
</usage>
</directivesynopsis>


<directivesynopsis>
<name>LuaHookMapToStorage</name>
<description>Provide a hook for the map_to_storage phase of request processing</description>
<syntax>LuaHookMapToStorage  /path/to/lua/script.lua hook_function_name</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
    <usage>
    <p>Like <directive>LuaHookTranslateName</directive> but executed at the
    map-to-storage phase of a request. Modules like <module>mod_cache</module> run at this phase,
    which makes for an interesting example on what to do here:</p>
    <highlight language="config">
    LuaHookMapToStorage /path/to/lua/script.lua check_cache
    </highlight>
    <highlight language="lua">
require"apache2"
cached_files = {}

function read_file(filename)
    local input = io.open(filename, "r")
    if input then
        local data = input:read("*a")
        cached_files[filename] = data
        file = cached_files[filename]
        input:close()
    end
    return cached_files[filename]
end

function check_cache(r)
    if r.filename:match("%.png$") then -- Only match PNG files
        local file = cached_files[r.filename] -- Check cache entries
        if not file then
            file = read_file(r.filename)  -- Read file into cache
        end
        if file then -- If file exists, write it out
            r.status = 200
            r:write(file)
            r:info(("Sent %s to client from cache"):format(r.filename))
            return apache2.DONE -- skip default handler for PNG files
        end
    end
    return apache2.DECLINED -- If we had nothing to do, let others serve this.
end
    </highlight>

    </usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaHookCheckUserID</name>
<description>Provide a hook for the check_user_id phase of request processing</description>
<syntax>LuaHookCheckUserID  /path/to/lua/script.lua hook_function_name</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
<!-- Third argument does not work at the moment!
<compatibility>The optional third argument is supported in 2.3.15 and later</compatibility>
<usage><p>...</p>
   <note><title>Ordering</title><p>The optional arguments "early" or "late"
   control when this script runs relative to other modules.</p></note>
</usage>
-->
</directivesynopsis>

<directivesynopsis>
<name>LuaHookTypeChecker</name>
<description>Provide a hook for the type_checker phase of request processing</description>
<syntax>LuaHookTypeChecker  /path/to/lua/script.lua hook_function_name</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
    <usage><p>
    This directive provides a hook for the type_checker phase of the request processing.
    This phase is where requests are assigned a content type and a handler, and thus can
    be used to modify the type and handler based on input:
    </p>
    <highlight language="config">
    LuaHookTypeChecker /path/to/lua/script.lua type_checker
    </highlight>
    <highlight language="lua">
    function type_checker(r)
        if r.uri:match("%.to_gif$") then -- match foo.png.to_gif
            r.content_type = "image/gif" -- assign it the image/gif type
            r.handler = "gifWizard"      -- tell the gifWizard module to handle this
            r.filename = r.uri:gsub("%.to_gif$", "") -- fix the filename requested
            return apache2.OK
        end

        return apache2.DECLINED
    end
    </highlight>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaHookAuthChecker</name>
<description>Provide a hook for the auth_checker phase of request processing</description>
<syntax>LuaHookAuthChecker  /path/to/lua/script.lua hook_function_name [early|late]</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
<compatibility>The optional third argument is supported in 2.3.15 and later</compatibility>
<usage>
<p>Invoke a lua function in the auth_checker phase of processing
a request.  This can be used to implement arbitrary authentication
and authorization checking.  A very simple example:
</p>
<highlight language="lua">
require 'apache2'

-- fake authcheck hook
-- If request has no auth info, set the response header and
-- return a 401 to ask the browser for basic auth info.
-- If request has auth info, don't actually look at it, just
-- pretend we got userid 'foo' and validated it.
-- Then check if the userid is 'foo' and accept the request.
function authcheck_hook(r)

   -- look for auth info
   auth = r.headers_in['Authorization']
   if auth ~= nil then
     -- fake the user
     r.user = 'foo'
   end

   if r.user == nil then
      r:debug("authcheck: user is nil, returning 401")
      r.err_headers_out['WWW-Authenticate'] = 'Basic realm="WallyWorld"'
      return 401
   elseif r.user == "foo" then
      r:debug('user foo: OK')
   else
      r:debug("authcheck: user='" .. r.user .. "'")
      r.err_headers_out['WWW-Authenticate'] = 'Basic realm="WallyWorld"'
      return 401
   end
   return apache2.OK
end
</highlight>
   <note><title>Ordering</title><p>The optional arguments "early" or "late"
   control when this script runs relative to other modules.</p></note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaHookAccessChecker</name>
<description>Provide a hook for the access_checker phase of request processing</description>
<syntax>LuaHookAccessChecker  /path/to/lua/script.lua  hook_function_name [early|late]</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
<compatibility>The optional third argument is supported in 2.3.15 and later</compatibility>
<usage>
<p>Add your hook to the access_checker phase.  An access checker
hook function usually returns OK, DECLINED, or HTTP_FORBIDDEN.</p>
   <note><title>Ordering</title><p>The optional arguments "early" or "late"
   control when this script runs relative to other modules.</p></note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaHookInsertFilter</name>
<description>Provide a hook for the insert_filter phase of request processing</description>
<syntax>LuaHookInsertFilter  /path/to/lua/script.lua hook_function_name</syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
    <usage><p>Not Yet Implemented</p></usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaInherit</name>
<description>Controls how parent configuration sections are merged into children</description>
<syntax>LuaInherit none|parent-first|parent-last</syntax>
<default>LuaInherit parent-first</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context>
</contextlist>
<override>All</override>
<compatibility>2.4.0 and later</compatibility>
    <usage><p>By default, if LuaHook* directives are used in overlapping
    Directory or Location configuration sections, the scripts defined in the
    more specific section are run <em>after</em> those defined in the more
    generic section (LuaInherit parent-first).  You can reverse this order, or
    make the parent context not apply at all.</p>

    <p> In previous 2.3.x releases, the default was effectively to ignore LuaHook*
    directives from parent configuration sections.</p></usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaQuickHandler</name>
<description>Provide a hook for the quick handler of request processing</description>
<syntax>LuaQuickHandler /path/to/script.lua hook_function_name</syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>
<override>All</override>
<usage>
    <p>
    This phase is run immediately after the request has been mapped to a virtual host,
    and can be used to either do some request processing before the other phases kick
    in, or to serve a request without the need to translate, map to storage et cetera.
    As this phase is run before anything else, directives such as <directive
   type="section" module="core">Location</directive> or <directive
   type="section" module="core">Directory</directive> are void in this phase, just as
    URIs have not been properly parsed yet.
    </p>
   <note><title>Context</title><p>This directive is not valid in <directive
   type="section" module="core">Directory</directive>, <directive
   type="section" module="core">Files</directive>, or htaccess
   context.</p></note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaAuthzProvider</name>
<description>Plug an authorization provider function into <module>mod_authz_core</module>
</description>
<syntax>LuaAuthzProvider provider_name /path/to/lua/script.lua function_name</syntax>
<contextlist><context>server config</context> </contextlist>
<compatibility>2.4.3 and later</compatibility>

<usage>
<p>After a lua function has been registered as authorization provider, it can be used
with the <directive module="mod_authz_core">Require</directive> directive:</p>

<highlight language="config">
LuaRoot /usr/local/apache2/lua
LuaAuthzProvider foo authz.lua authz_check_foo
&lt;Location "/"&gt;
  Require foo johndoe
&lt;/Location&gt;
</highlight>
<highlight language="lua">
require "apache2"
function authz_check_foo(r, who)
    if r.user ~= who then return apache2.AUTHZ_DENIED
    return apache2.AUTHZ_GRANTED
end
</highlight>


</usage>
</directivesynopsis>


<directivesynopsis>
<name>LuaInputFilter</name>
<description>Provide a Lua function for content input filtering</description>
<syntax>LuaInputFilter filter_name /path/to/lua/script.lua function_name</syntax>
<contextlist><context>server config</context> </contextlist>
<override>All</override>
<compatibility>2.4.5 and later</compatibility>

<usage>
<p>Provides a means of adding a Lua function as an input filter.
As with output filters, input filters work as coroutines,
first yielding before buffers are sent, then yielding whenever
a bucket needs to be passed down the chain, and finally (optionally)
yielding anything that needs to be appended to the input data. The
global variable <code>bucket</code> holds the buckets as they are passed
onto the Lua script:
</p>

<highlight language="config">
LuaInputFilter myInputFilter /www/filter.lua input_filter
&lt;Files "*.lua"&gt;
  SetInputFilter myInputFilter
&lt;/Files&gt;
</highlight>
<highlight language="lua">
--[[
    Example input filter that converts all POST data to uppercase.
]]--
function input_filter(r)
    print("luaInputFilter called") -- debug print
    coroutine.yield() -- Yield and wait for buckets
    while bucket do -- For each bucket, do...
        local output = string.upper(bucket) -- Convert all POST data to uppercase
        coroutine.yield(output) -- Send converted data down the chain
    end
    -- No more buckets available.
    coroutine.yield("&amp;filterSignature=1234") -- Append signature at the end
end
</highlight>
<p>
The input filter supports denying/skipping a filter if it is deemed unwanted:
</p>
<highlight language="lua">
function input_filter(r)
    if not good then
        return -- Simply deny filtering, passing on the original content instead
    end
    coroutine.yield() -- wait for buckets
    ... -- insert filter stuff here
end
</highlight>
<p>
See "<a href="#modifying_buckets">Modifying contents with Lua
filters</a>" for more information.
</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>LuaOutputFilter</name>
<description>Provide a Lua function for content output filtering</description>
<syntax>LuaOutputFilter filter_name /path/to/lua/script.lua function_name</syntax>
<contextlist><context>server config</context> </contextlist>
<override>All</override>
<compatibility>2.4.5 and later</compatibility>

<usage>
<p>Provides a means of adding a Lua function as an output filter.
As with input filters, output filters work as coroutines,
first yielding before buffers are sent, then yielding whenever
a bucket needs to be passed down the chain, and finally (optionally)
yielding anything that needs to be appended to the input data. The
global variable <code>bucket</code> holds the buckets as they are passed
onto the Lua script:
</p>

<highlight language="config">
LuaOutputFilter myOutputFilter /www/filter.lua output_filter
&lt;Files "*.lua"&gt;
  SetOutputFilter myOutputFilter
&lt;/Files&gt;
</highlight>
<highlight language="lua">
--[[
    Example output filter that escapes all HTML entities in the output
]]--
function output_filter(r)
    coroutine.yield("(Handled by myOutputFilter)&lt;br/&gt;\n") -- Prepend some data to the output,
                                                          -- yield and wait for buckets.
    while bucket do -- For each bucket, do...
        local output = r:escape_html(bucket) -- Escape all output
        coroutine.yield(output) -- Send converted data down the chain
    end
    -- No more buckets available.
end
</highlight>
<p>
As with the input filter, the output filter supports denying/skipping a filter
if it is deemed unwanted:
</p>
<highlight language="lua">
function output_filter(r)
    if not r.content_type:match("text/html") then
        return -- Simply deny filtering, passing on the original content instead
    end
    coroutine.yield() -- wait for buckets
    ... -- insert filter stuff here
end
</highlight>
<note><title>Lua filters with <module>mod_filter</module></title>
<p> When a Lua filter is used as the underlying provider via the
<directive module="mod_filter">FilterProvider</directive> directive, filtering
will only work when the <var>filter-name</var> is identical to the <var>provider-name</var>.
</p> </note>

<p>
See "<a href="#modifying_buckets">Modifying contents with Lua filters</a>" for more
information.
</p>

</usage>
</directivesynopsis>



</modulesynopsis>