qa-index.php

<?php
/*
	Question2Answer by Gideon Greenspan and contributors
	http://www.question2answer.org/

	File: qa-include/qa-index.php
	Description: The Grand Central of Q2A - most requests come through here


	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	More about this license: http://www.question2answer.org/license.php
*/

//	Try our best to set base path here just in case it wasn't set in index.php (pre version 1.0.1)

	if (!defined('QA_BASE_DIR'))
		define('QA_BASE_DIR', dirname(empty($_SERVER['SCRIPT_FILENAME']) ? dirname(__FILE__) : $_SERVER['SCRIPT_FILENAME']).'/');


//	If this is an special non-page request, branch off here

	if (isset($_POST['qa']) && $_POST['qa'] == 'ajax')
		require 'qa-ajax.php';

	elseif (isset($_GET['qa']) && $_GET['qa'] == 'image')
		require 'qa-image.php';

	elseif (isset($_GET['qa']) && $_GET['qa'] == 'blob')
		require 'qa-blob.php';

	else {

	//	Otherwise, load the Q2A base file which sets up a bunch of crucial stuff

		require 'qa-base.php';

		/**
		 * Determine the request and root of the installation, and the requested start position used by many pages.
		 *
		 * Apache and Nginx behave slightly differently:
		 *   Apache qa-rewrite unescapes characters, converts `+` to ` `, cuts off at `#` or `&`
		 *   Nginx qa-rewrite unescapes characters, retains `+`, contains true path
		 */
		function qa_index_set_request()
		{
			if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

			$relativedepth = 0;

			if (isset($_GET['qa-rewrite'])) { // URLs rewritten by .htaccess or Nginx
				$urlformat = QA_URL_FORMAT_NEAT;
				$qa_rewrite = strtr(qa_gpc_to_string($_GET['qa-rewrite']), '+', ' '); // strtr required by Nginx
				$requestparts = explode('/', $qa_rewrite);
				unset($_GET['qa-rewrite']);

				if (!empty($_SERVER['REQUEST_URI'])) { // workaround for the fact that Apache unescapes characters while rewriting
					$origpath = $_SERVER['REQUEST_URI'];
					$_GET = array();

					$questionpos = strpos($origpath, '?');
					if (is_numeric($questionpos)) {
						$params = explode('&', substr($origpath, $questionpos+1));

						foreach ($params as $param) {
							if (preg_match('/^([^\=]*)(\=(.*))?$/', $param, $matches)) {
								$argument = strtr(urldecode($matches[1]), '.', '_'); // simulate PHP's $_GET behavior
								$_GET[$argument] = qa_string_to_gpc(urldecode(@$matches[3]));
							}
						}

						$origpath = substr($origpath, 0, $questionpos);
					}

					// Generally we assume that $_GET['qa-rewrite'] has the right path depth, but this won't be the case if there's
					// a & or # somewhere in the middle of the path, due to Apache unescaping. So we make a special case for that.
					// If 'REQUEST_URI' and 'qa-rewrite' already match (as on Nginx), we can skip this.
					$normalizedpath = urldecode($origpath);
					if (substr($normalizedpath, -strlen($qa_rewrite)) !== $qa_rewrite) {
						$keepparts = count($requestparts);
						$requestparts = explode('/', urldecode($origpath)); // new request calculated from $_SERVER['REQUEST_URI']

						// loop forwards so we capture all parts
						for ($part = 0, $max = count($requestparts); $part < $max; $part++) {
							if (is_numeric(strpos($requestparts[$part], '&')) || is_numeric(strpos($requestparts[$part], '#'))) {
								$keepparts += count($requestparts) - $part - 1; // this is how many parts remain
								break;
							}
						}

						$requestparts = array_slice($requestparts, -$keepparts); // remove any irrelevant parts from the beginning
					}
				}

				$relativedepth = count($requestparts);
			}
			elseif (isset($_GET['qa'])) {
				if (strpos($_GET['qa'], '/') === false) {
					$urlformat = ( empty($_SERVER['REQUEST_URI']) || strpos($_SERVER['REQUEST_URI'], '/index.php') !== false )
						? QA_URL_FORMAT_SAFEST : QA_URL_FORMAT_PARAMS;
					$requestparts = array(qa_gpc_to_string($_GET['qa']));

					for ($part = 1; $part < 10; $part++) {
						if (isset($_GET['qa_'.$part])) {
							$requestparts[] = qa_gpc_to_string($_GET['qa_'.$part]);
							unset($_GET['qa_'.$part]);
						}
					}
				}
				else {
					$urlformat = QA_URL_FORMAT_PARAM;
					$requestparts = explode('/', qa_gpc_to_string($_GET['qa']));
				}

				unset($_GET['qa']);
			}
			else {
				$normalizedpath = strtr($_SERVER['PHP_SELF'], '+', ' '); // seems necessary, and plus does not work with this scheme
				$indexpath = '/index.php/';
				$indexpos = strpos($normalizedpath, $indexpath);

				if (!empty($_SERVER['REQUEST_URI'])) { // workaround for the fact that Apache unescapes characters
					$origpath = $_SERVER['REQUEST_URI'];
					$questionpos = strpos($origpath, '?');
					if ($questionpos !== false) {
						$origpath = substr($origpath, 0, $questionpos);
					}

					$normalizedpath = urldecode($origpath);
					$indexpos = strpos($normalizedpath, $indexpath);
				}

				if (is_numeric($indexpos)) {
					$urlformat = QA_URL_FORMAT_INDEX;
					$requestparts = explode('/', substr($normalizedpath, $indexpos + strlen($indexpath)));
					$relativedepth = 1 + count($requestparts);
				}
				else {
					$urlformat = null; // at home page so can't identify path type
					$requestparts = array();
				}
			}

			foreach ($requestparts as $part => $requestpart) { // remove any blank parts
				if (!strlen($requestpart))
					unset($requestparts[$part]);
			}

			reset($requestparts);
			$key = key($requestparts);

			$requestkey = isset($requestparts[$key]) ? $requestparts[$key] : '';
			$replacement = array_search($requestkey, qa_get_request_map());
			if ($replacement !== false)
				$requestparts[$key] = $replacement;

			qa_set_request(
				implode('/', $requestparts),
				($relativedepth > 1 ? str_repeat('../', $relativedepth - 1) : './'),
				$urlformat
			);
		}

		qa_index_set_request();


	//	Branch off to appropriate file for further handling

		$requestlower = strtolower(qa_request());

		if ($requestlower == 'install')
			require QA_INCLUDE_DIR.'qa-install.php';
		elseif ($requestlower == 'url/test/'.QA_URL_TEST_STRING)
			require QA_INCLUDE_DIR.'qa-url-test.php';
		else {
			// enable gzip compression for output (needs to come early)
			// skip admin pages since some of these contain lengthy processes
			if (QA_HTML_COMPRESSION && substr($requestlower, 0, 6) != 'admin/') {
				if (extension_loaded('zlib') && !headers_sent())
					ob_start('ob_gzhandler');
			}

			if (substr($requestlower, 0, 5) == 'feed/')
				require QA_INCLUDE_DIR.'qa-feed.php';
			else
				require QA_INCLUDE_DIR.'qa-page.php';
		}
	}

	qa_report_process_stage('shutdown');