<?php

/**
 * This file has the very important job of ensuring forum security.
 * This task includes banning and permissions, namely.
 *
 * Simple Machines Forum (SMF)
 *
 * @package SMF
 * @author Simple Machines https://www.simplemachines.org
 * @copyright 2022 Simple Machines and individual contributors
 * @license https://www.simplemachines.org/about/smf/license.php BSD
 *
 * @version 2.1.3
 */

if (!defined('SMF'))
	die('No direct access...');

/**
 * Check if the user is who he/she says he is
 * Makes sure the user is who they claim to be by requiring a password to be typed in every hour.
 * Is turned on and off by the securityDisable setting.
 * Uses the adminLogin() function of Subs-Auth.php if they need to login, which saves all request (post and get) data.
 *
 * @param string $type What type of session this is
 * @param string $force When true, require a password even if we normally wouldn't
 * @return void|string Returns 'session_verify_fail' if verification failed
 */
function validateSession($type = 'admin', $force = false)
{
	global $modSettings, $sourcedir, $user_info;

	// We don't care if the option is off, because Guests should NEVER get past here.
	is_not_guest();

	// Validate what type of session check this is.
	$types = array();
	call_integration_hook('integrate_validateSession', array(&$types));
	$type = in_array($type, $types) || $type == 'moderate' ? $type : 'admin';

	// If we're using XML give an additional ten minutes grace as an admin can't log on in XML mode.
	$refreshTime = isset($_GET['xml']) ? 4200 : 3600;

	if (empty($force))
	{
		// Is the security option off?
		if (!empty($modSettings['securityDisable' . ($type != 'admin' ? '_' . $type : '')]))
			return;

		// Or are they already logged in?, Moderator or admin session is need for this area
		if ((!empty($_SESSION[$type . '_time']) && $_SESSION[$type . '_time'] + $refreshTime >= time()) || (!empty($_SESSION['admin_time']) && $_SESSION['admin_time'] + $refreshTime >= time()))
			return;
	}

	require_once($sourcedir . '/Subs-Auth.php');

	// Posting the password... check it.
	if (isset($_POST[$type . '_pass']))
	{
		// Check to ensure we're forcing SSL for authentication
		if (!empty($modSettings['force_ssl']) && empty($maintenance) && !httpsOn())
			fatal_lang_error('login_ssl_required');

		checkSession();

		$good_password = in_array(true, call_integration_hook('integrate_verify_password', array($user_info['username'], $_POST[$type . '_pass'], false)), true);

		// Password correct?
		if ($good_password || hash_verify_password($user_info['username'], $_POST[$type . '_pass'], $user_info['passwd']))
		{
			$_SESSION[$type . '_time'] = time();
			unset($_SESSION['request_referer']);
			return;
		}
	}

	// Better be sure to remember the real referer
	if (empty($_SESSION['request_referer']))
		$_SESSION['request_referer'] = isset($_SERVER['HTTP_REFERER']) ? @parse_iri($_SERVER['HTTP_REFERER']) : array();
	elseif (empty($_POST))
		unset($_SESSION['request_referer']);

	// Need to type in a password for that, man.
	if (!isset($_GET['xml']))
		adminLogin($type);
	else
		return 'session_verify_fail';
}

/**
 * Require a user who is logged in. (not a guest.)
 * Checks if the user is currently a guest, and if so asks them to login with a message telling them why.
 * Message is what to tell them when asking them to login.
 *
 * @param string $message The message to display to the guest
 */
function is_not_guest($message = '')
{
	global $user_info, $txt, $context, $scripturl, $modSettings;

	// Luckily, this person isn't a guest.
	if (!$user_info['is_guest'])
		return;

	// Log what they were trying to do didn't work)
	if (!empty($modSettings['who_enabled']))
		$_GET['error'] = 'guest_login';
	writeLog(true);

	// Just die.
	if (isset($_REQUEST['xml']))
		obExit(false);

	// Attempt to detect if they came from dlattach.
	if (SMF != 'SSI' && empty($context['theme_loaded']))
		loadTheme();

	// Never redirect to an attachment
	if (strpos($_SERVER['REQUEST_URL'], 'dlattach') === false)
		$_SESSION['login_url'] = $_SERVER['REQUEST_URL'];

	// Load the Login template and language file.
	loadLanguage('Login');

	// Apparently we're not in a position to handle this now. Let's go to a safer location for now.
	if (empty($context['template_layers']))
	{
		$_SESSION['login_url'] = $scripturl . '?' . $_SERVER['QUERY_STRING'];
		redirectexit('action=login');
	}
	else
	{
		loadTemplate('Login');
		$context['sub_template'] = 'kick_guest';
		$context['robot_no_index'] = true;
	}

	// Use the kick_guest sub template...
	$context['kick_message'] = $message;
	$context['page_title'] = $txt['login'];

	obExit();

	// We should never get to this point, but if we did we wouldn't know the user isn't a guest.
	trigger_error('No direct access...', E_USER_ERROR);
}

/**
 * Do banning related stuff.  (ie. disallow access....)
 * Checks if the user is banned, and if so dies with an error.
 * Caches this information for optimization purposes.
 *
 * @param bool $forceCheck Whether to force a recheck
 */
function is_not_banned($forceCheck = false)
{
	global $txt, $modSettings, $context, $user_info;
	global $sourcedir, $cookiename, $user_settings, $smcFunc;

	// You cannot be banned if you are an admin - doesn't help if you log out.
	if ($user_info['is_admin'])
		return;

	// Only check the ban every so often. (to reduce load.)
	if ($forceCheck || !isset($_SESSION['ban']) || empty($modSettings['banLastUpdated']) || ($_SESSION['ban']['last_checked'] < $modSettings['banLastUpdated']) || $_SESSION['ban']['id_member'] != $user_info['id'] || $_SESSION['ban']['ip'] != $user_info['ip'] || $_SESSION['ban']['ip2'] != $user_info['ip2'] || (isset($user_info['email'], $_SESSION['ban']['email']) && $_SESSION['ban']['email'] != $user_info['email']))
	{
		// Innocent until proven guilty.  (but we know you are! :P)
		$_SESSION['ban'] = array(
			'last_checked' => time(),
			'id_member' => $user_info['id'],
			'ip' => $user_info['ip'],
			'ip2' => $user_info['ip2'],
			'email' => $user_info['email'],
		);

		$ban_query = array();
		$ban_query_vars = array('current_time' => time());
		$flag_is_activated = false;

		// Check both IP addresses.
		foreach (array('ip', 'ip2') as $ip_number)
		{
			if ($ip_number == 'ip2' && $user_info['ip2'] == $user_info['ip'])
				continue;
			$ban_query[] = ' {inet:' . $ip_number . '} BETWEEN bi.ip_low and bi.ip_high';
			$ban_query_vars[$ip_number] = $user_info[$ip_number];
			// IP was valid, maybe there's also a hostname...
			if (empty($modSettings['disableHostnameLookup']) && $user_info[$ip_number] != 'unknown')
			{
				$hostname = host_from_ip($user_info[$ip_number]);
				if (strlen($hostname) > 0)
				{
					$ban_query[] = '({string:hostname' . $ip_number . '} LIKE bi.hostname)';
					$ban_query_vars['hostname' . $ip_number] = $hostname;
				}
			}
		}

		// Is their email address banned?
		if (strlen($user_info['email']) != 0)
		{
			$ban_query[] = '({string:email} LIKE bi.email_address)';
			$ban_query_vars['email'] = $user_info['email'];
		}

		// How about this user?
		if (!$user_info['is_guest'] && !empty($user_info['id']))
		{
			$ban_query[] = 'bi.id_member = {int:id_member}';
			$ban_query_vars['id_member'] = $user_info['id'];
		}

		// Check the ban, if there's information.
		if (!empty($ban_query))
		{
			$restrictions = array(
				'cannot_access',
				'cannot_login',
				'cannot_post',
				'cannot_register',
			);
			$request = $smcFunc['db_query']('', '
				SELECT bi.id_ban, bi.email_address, bi.id_member, bg.cannot_access, bg.cannot_register,
					bg.cannot_post, bg.cannot_login, bg.reason, COALESCE(bg.expire_time, 0) AS expire_time
				FROM {db_prefix}ban_items AS bi
					INNER JOIN {db_prefix}ban_groups AS bg ON (bg.id_ban_group = bi.id_ban_group AND (bg.expire_time IS NULL OR bg.expire_time > {int:current_time}))
				WHERE
					(' . implode(' OR ', $ban_query) . ')',
				$ban_query_vars
			);
			// Store every type of ban that applies to you in your session.
			while ($row = $smcFunc['db_fetch_assoc']($request))
			{
				foreach ($restrictions as $restriction)
					if (!empty($row[$restriction]))
					{
						$_SESSION['ban'][$restriction]['reason'] = $row['reason'];
						$_SESSION['ban'][$restriction]['ids'][] = $row['id_ban'];
						if (!isset($_SESSION['ban']['expire_time']) || ($_SESSION['ban']['expire_time'] != 0 && ($row['expire_time'] == 0 || $row['expire_time'] > $_SESSION['ban']['expire_time'])))
							$_SESSION['ban']['expire_time'] = $row['expire_time'];

						if (!$user_info['is_guest'] && $restriction == 'cannot_access' && ($row['id_member'] == $user_info['id'] || $row['email_address'] == $user_info['email']))
							$flag_is_activated = true;
					}
			}
			$smcFunc['db_free_result']($request);
		}

		// Mark the cannot_access and cannot_post bans as being 'hit'.
		if (isset($_SESSION['ban']['cannot_access']) || isset($_SESSION['ban']['cannot_post']) || isset($_SESSION['ban']['cannot_login']))
			log_ban(array_merge(isset($_SESSION['ban']['cannot_access']) ? $_SESSION['ban']['cannot_access']['ids'] : array(), isset($_SESSION['ban']['cannot_post']) ? $_SESSION['ban']['cannot_post']['ids'] : array(), isset($_SESSION['ban']['cannot_login']) ? $_SESSION['ban']['cannot_login']['ids'] : array()));

		// If for whatever reason the is_activated flag seems wrong, do a little work to clear it up.
		if ($user_info['id'] && (($user_settings['is_activated'] >= 10 && !$flag_is_activated)
			|| ($user_settings['is_activated'] < 10 && $flag_is_activated)))
		{
			require_once($sourcedir . '/ManageBans.php');
			updateBanMembers();
		}
	}

	// Hey, I know you! You're ehm...
	if (!isset($_SESSION['ban']['cannot_access']) && !empty($_COOKIE[$cookiename . '_']))
	{
		$bans = explode(',', $_COOKIE[$cookiename . '_']);
		foreach ($bans as $key => $value)
			$bans[$key] = (int) $value;
		$request = $smcFunc['db_query']('', '
			SELECT bi.id_ban, bg.reason, COALESCE(bg.expire_time, 0) AS expire_time
			FROM {db_prefix}ban_items AS bi
				INNER JOIN {db_prefix}ban_groups AS bg ON (bg.id_ban_group = bi.id_ban_group)
			WHERE bi.id_ban IN ({array_int:ban_list})
				AND (bg.expire_time IS NULL OR bg.expire_time > {int:current_time})
				AND bg.cannot_access = {int:cannot_access}
			LIMIT {int:limit}',
			array(
				'cannot_access' => 1,
				'ban_list' => $bans,
				'current_time' => time(),
				'limit' => count($bans),
			)
		);
		while ($row = $smcFunc['db_fetch_assoc']($request))
		{
			$_SESSION['ban']['cannot_access']['ids'][] = $row['id_ban'];
			$_SESSION['ban']['cannot_access']['reason'] = $row['reason'];
			$_SESSION['ban']['expire_time'] = $row['expire_time'];
		}
		$smcFunc['db_free_result']($request);

		// My mistake. Next time better.
		if (!isset($_SESSION['ban']['cannot_access']))
		{
			require_once($sourcedir . '/Subs-Auth.php');
			$cookie_url = url_parts(!empty($modSettings['localCookies']), !empty($modSettings['globalCookies']));
			smf_setcookie($cookiename . '_', '', time() - 3600, $cookie_url[1], $cookie_url[0], false, false);
		}
	}

	// If you're fully banned, it's end of the story for you.
	if (isset($_SESSION['ban']['cannot_access']))
	{
		// We don't wanna see you!
		if (!$user_info['is_guest'])
			$smcFunc['db_query']('', '
				DELETE FROM {db_prefix}log_online
				WHERE id_member = {int:current_member}',
				array(
					'current_member' => $user_info['id'],
				)
			);

		// 'Log' the user out.  Can't have any funny business... (save the name!)
		$old_name = isset($user_info['name']) && $user_info['name'] != '' ? $user_info['name'] : $txt['guest_title'];
		$user_info['name'] = '';
		$user_info['username'] = '';
		$user_info['is_guest'] = true;
		$user_info['is_admin'] = false;
		$user_info['permissions'] = array();
		$user_info['id'] = 0;
		$context['user'] = array(
			'id' => 0,
			'username' => '',
			'name' => $txt['guest_title'],
			'is_guest' => true,
			'is_logged' => false,
			'is_admin' => false,
			'is_mod' => false,
			'can_mod' => false,
			'language' => $user_info['language'],
		);

		// A goodbye present.
		require_once($sourcedir . '/Subs-Auth.php');
		require_once($sourcedir . '/LogInOut.php');
		$cookie_url = url_parts(!empty($modSettings['localCookies']), !empty($modSettings['globalCookies']));
		smf_setcookie($cookiename . '_', implode(',', $_SESSION['ban']['cannot_access']['ids']), time() + 3153600, $cookie_url[1], $cookie_url[0], false, false);

		// Don't scare anyone, now.
		$_GET['action'] = '';
		$_GET['board'] = '';
		$_GET['topic'] = '';
		writeLog(true);
		Logout(true, false);

		// You banned, sucka!
		fatal_error(sprintf($txt['your_ban'], $old_name) . (empty($_SESSION['ban']['cannot_access']['reason']) ? '' : '<br>' . $_SESSION['ban']['cannot_access']['reason']) . '<br>' . (!empty($_SESSION['ban']['expire_time']) ? sprintf($txt['your_ban_expires'], timeformat($_SESSION['ban']['expire_time'], false)) : $txt['your_ban_expires_never']), false, 403);

		// If we get here, something's gone wrong.... but let's try anyway.
		trigger_error('No direct access...', E_USER_ERROR);
	}
	// You're not allowed to log in but yet you are. Let's fix that.
	elseif (isset($_SESSION['ban']['cannot_login']) && !$user_info['is_guest'])
	{
		// We don't wanna see you!
		$smcFunc['db_query']('', '
			DELETE FROM {db_prefix}log_online
			WHERE id_member = {int:current_member}',
			array(
				'current_member' => $user_info['id'],
			)
		);

		// 'Log' the user out.  Can't have any funny business... (save the name!)
		$old_name = isset($user_info['name']) && $user_info['name'] != '' ? $user_info['name'] : $txt['guest_title'];
		$user_info['name'] = '';
		$user_info['username'] = '';
		$user_info['is_guest'] = true;
		$user_info['is_admin'] = false;
		$user_info['permissions'] = array();
		$user_info['id'] = 0;
		$context['user'] = array(
			'id' => 0,
			'username' => '',
			'name' => $txt['guest_title'],
			'is_guest' => true,
			'is_logged' => false,
			'is_admin' => false,
			'is_mod' => false,
			'can_mod' => false,
			'language' => $user_info['language'],
		);

		// SMF's Wipe 'n Clean(r) erases all traces.
		$_GET['action'] = '';
		$_GET['board'] = '';
		$_GET['topic'] = '';
		writeLog(true);

		require_once($sourcedir . '/LogInOut.php');
		Logout(true, false);

		fatal_error(sprintf($txt['your_ban'], $old_name) . (empty($_SESSION['ban']['cannot_login']['reason']) ? '' : '<br>' . $_SESSION['ban']['cannot_login']['reason']) . '<br>' . (!empty($_SESSION['ban']['expire_time']) ? sprintf($txt['your_ban_expires'], timeformat($_SESSION['ban']['expire_time'], false)) : $txt['your_ban_expires_never']) . '<br>' . $txt['ban_continue_browse'], false, 403);
	}

	// Fix up the banning permissions.
	if (isset($user_info['permissions']))
		banPermissions();
}

/**
 * Fix permissions according to ban status.
 * Applies any states of banning by removing permissions the user cannot have.
 */
function banPermissions()
{
	global $user_info, $sourcedir, $modSettings, $context;

	// Somehow they got here, at least take away all permissions...
	if (isset($_SESSION['ban']['cannot_access']))
		$user_info['permissions'] = array();
	// Okay, well, you can watch, but don't touch a thing.
	elseif (isset($_SESSION['ban']['cannot_post']) || (!empty($modSettings['warning_mute']) && $modSettings['warning_mute'] <= $user_info['warning']))
	{
		$denied_permissions = array(
			'pm_send',
			'calendar_post', 'calendar_edit_own', 'calendar_edit_any',
			'poll_post',
			'poll_add_own', 'poll_add_any',
			'poll_edit_own', 'poll_edit_any',
			'poll_lock_own', 'poll_lock_any',
			'poll_remove_own', 'poll_remove_any',
			'manage_attachments', 'manage_smileys', 'manage_boards', 'admin_forum', 'manage_permissions',
			'moderate_forum', 'manage_membergroups', 'manage_bans', 'send_mail', 'edit_news',
			'profile_identity_any', 'profile_extra_any', 'profile_title_any',
			'profile_forum_any', 'profile_other_any', 'profile_signature_any',
			'post_new', 'post_reply_own', 'post_reply_any',
			'delete_own', 'delete_any', 'delete_replies',
			'make_sticky',
			'merge_any', 'split_any',
			'modify_own', 'modify_any', 'modify_replies',
			'move_any',
			'lock_own', 'lock_any',
			'remove_own', 'remove_any',
			'post_unapproved_topics', 'post_unapproved_replies_own', 'post_unapproved_replies_any',
		);
		call_integration_hook('integrate_post_ban_permissions', array(&$denied_permissions));
		$user_info['permissions'] = array_diff($user_info['permissions'], $denied_permissions);
	}
	// Are they absolutely under moderation?
	elseif (!empty($modSettings['warning_moderate']) && $modSettings['warning_moderate'] <= $user_info['warning'])
	{
		// Work out what permissions should change...
		$permission_change = array(
			'post_new' => 'post_unapproved_topics',
			'post_reply_own' => 'post_unapproved_replies_own',
			'post_reply_any' => 'post_unapproved_replies_any',
			'post_attachment' => 'post_unapproved_attachments',
		);
		call_integration_hook('integrate_warn_permissions', array(&$permission_change));
		foreach ($permission_change as $old => $new)
		{
			if (!in_array($old, $user_info['permissions']))
				unset($permission_change[$old]);
			else
				$user_info['permissions'][] = $new;
		}
		$user_info['permissions'] = array_diff($user_info['permissions'], array_keys($permission_change));
	}

	// @todo Find a better place to call this? Needs to be after permissions loaded!
	// Finally, some bits we cache in the session because it saves queries.
	if (isset($_SESSION['mc']) && $_SESSION['mc']['time'] > $modSettings['settings_updated'] && $_SESSION['mc']['id'] == $user_info['id'])
		$user_info['mod_cache'] = $_SESSION['mc'];
	else
	{
		require_once($sourcedir . '/Subs-Auth.php');
		rebuildModCache();
	}

	// Now that we have the mod cache taken care of lets setup a cache for the number of mod reports still open
	if (isset($_SESSION['rc']['reports']) && isset($_SESSION['rc']['member_reports']) && $_SESSION['rc']['time'] > $modSettings['last_mod_report_action'] && $_SESSION['rc']['id'] == $user_info['id'])
	{
		$context['open_mod_reports'] = $_SESSION['rc']['reports'];
		$context['open_member_reports'] = $_SESSION['rc']['member_reports'];
	}
	elseif ($_SESSION['mc']['bq'] != '0=1')
	{
		require_once($sourcedir . '/Subs-ReportedContent.php');
		$context['open_mod_reports'] = recountOpenReports('posts');
		$context['open_member_reports'] = recountOpenReports('members');
	}
	else
	{
		$context['open_mod_reports'] = 0;
		$context['open_member_reports'] = 0;
	}
}

/**
 * Log a ban in the database.
 * Log the current user in the ban logs.
 * Increment the hit counters for the specified ban ID's (if any.)
 *
 * @param array $ban_ids The IDs of the bans
 * @param string $email The email address associated with the user that triggered this hit
 */
function log_ban($ban_ids = array(), $email = null)
{
	global $user_info, $smcFunc;

	// Don't log web accelerators, it's very confusing...
	if (isset($_SERVER['HTTP_X_MOZ']) && $_SERVER['HTTP_X_MOZ'] == 'prefetch')
		return;

	$smcFunc['db_insert']('',
		'{db_prefix}log_banned',
		array('id_member' => 'int', 'ip' => 'inet', 'email' => 'string', 'log_time' => 'int'),
		array($user_info['id'], $user_info['ip'], ($email === null ? ($user_info['is_guest'] ? '' : $user_info['email']) : $email), time()),
		array('id_ban_log')
	);

	// One extra point for these bans.
	if (!empty($ban_ids))
		$smcFunc['db_query']('', '
			UPDATE {db_prefix}ban_items
			SET hits = hits + 1
			WHERE id_ban IN ({array_int:ban_ids})',
			array(
				'ban_ids' => $ban_ids,
			)
		);
}

/**
 * Checks if a given email address might be banned.
 * Check if a given email is banned.
 * Performs an immediate ban if the turns turns out positive.
 *
 * @param string $email The email to check
 * @param string $restriction What type of restriction (cannot_post, cannot_register, etc.)
 * @param string $error The error message to display if they are indeed banned
 */
function isBannedEmail($email, $restriction, $error)
{
	global $txt, $smcFunc;

	// Can't ban an empty email
	if (empty($email) || trim($email) == '')
		return;

	// Let's start with the bans based on your IP/hostname/memberID...
	$ban_ids = isset($_SESSION['ban'][$restriction]) ? $_SESSION['ban'][$restriction]['ids'] : array();
	$ban_reason = isset($_SESSION['ban'][$restriction]) ? $_SESSION['ban'][$restriction]['reason'] : '';

	// ...and add to that the email address you're trying to register.
	$request = $smcFunc['db_query']('', '
		SELECT bi.id_ban, bg.' . $restriction . ', bg.cannot_access, bg.reason
		FROM {db_prefix}ban_items AS bi
			INNER JOIN {db_prefix}ban_groups AS bg ON (bg.id_ban_group = bi.id_ban_group)
		WHERE {string:email} LIKE bi.email_address
			AND (bg.' . $restriction . ' = {int:cannot_access} OR bg.cannot_access = {int:cannot_access})
			AND (bg.expire_time IS NULL OR bg.expire_time >= {int:now})',
		array(
			'email' => $email,
			'cannot_access' => 1,
			'now' => time(),
		)
	);
	while ($row = $smcFunc['db_fetch_assoc']($request))
	{
		if (!empty($row['cannot_access']))
		{
			$_SESSION['ban']['cannot_access']['ids'][] = $row['id_ban'];
			$_SESSION['ban']['cannot_access']['reason'] = $row['reason'];
		}
		if (!empty($row[$restriction]))
		{
			$ban_ids[] = $row['id_ban'];
			$ban_reason = $row['reason'];
		}
	}
	$smcFunc['db_free_result']($request);

	// You're in biiig trouble.  Banned for the rest of this session!
	if (isset($_SESSION['ban']['cannot_access']))
	{
		log_ban($_SESSION['ban']['cannot_access']['ids']);
		$_SESSION['ban']['last_checked'] = time();

		fatal_error(sprintf($txt['your_ban'], $txt['guest_title']) . $_SESSION['ban']['cannot_access']['reason'], false);
	}

	if (!empty($ban_ids))
	{
		// Log this ban for future reference.
		log_ban($ban_ids, $email);
		fatal_error($error . $ban_reason, false);
	}
}

/**
 * Make sure the user's correct session was passed, and they came from here.
 * Checks the current session, verifying that the person is who he or she should be.
 * Also checks the referrer to make sure they didn't get sent here.
 * Depends on the disableCheckUA setting, which is usually missing.
 * Will check GET, POST, or REQUEST depending on the passed type.
 * Also optionally checks the referring action if passed. (note that the referring action must be by GET.)
 *
 * @param string $type The type of check (post, get, request)
 * @param string $from_action The action this is coming from
 * @param bool $is_fatal Whether to die with a fatal error if the check fails
 * @return string The error message if is_fatal is false.
 */
function checkSession($type = 'post', $from_action = '', $is_fatal = true)
{
	global $context, $sc, $modSettings, $boardurl;

	// Is it in as $_POST['sc']?
	if ($type == 'post')
	{
		$check = isset($_POST[$_SESSION['session_var']]) ? $_POST[$_SESSION['session_var']] : (empty($modSettings['strictSessionCheck']) && isset($_POST['sc']) ? $_POST['sc'] : null);
		if ($check !== $sc)
			$error = 'session_timeout';
	}

	// How about $_GET['sesc']?
	elseif ($type == 'get')
	{
		$check = isset($_GET[$_SESSION['session_var']]) ? $_GET[$_SESSION['session_var']] : (empty($modSettings['strictSessionCheck']) && isset($_GET['sesc']) ? $_GET['sesc'] : null);
		if ($check !== $sc)
			$error = 'session_verify_fail';
	}

	// Or can it be in either?
	elseif ($type == 'request')
	{
		$check = isset($_GET[$_SESSION['session_var']]) ? $_GET[$_SESSION['session_var']] : (empty($modSettings['strictSessionCheck']) && isset($_GET['sesc']) ? $_GET['sesc'] : (isset($_POST[$_SESSION['session_var']]) ? $_POST[$_SESSION['session_var']] : (empty($modSettings['strictSessionCheck']) && isset($_POST['sc']) ? $_POST['sc'] : null)));

		if ($check !== $sc)
			$error = 'session_verify_fail';
	}

	// Verify that they aren't changing user agents on us - that could be bad.
	if ((!isset($_SESSION['USER_AGENT']) || $_SESSION['USER_AGENT'] != $_SERVER['HTTP_USER_AGENT']) && empty($modSettings['disableCheckUA']))
		$error = 'session_verify_fail';

	// Make sure a page with session check requirement is not being prefetched.
	if (isset($_SERVER['HTTP_X_MOZ']) && $_SERVER['HTTP_X_MOZ'] == 'prefetch')
	{
		ob_end_clean();
		send_http_status(403);
		die;
	}

	// Check the referring site - it should be the same server at least!
	if (isset($_SESSION['request_referer']))
		$referrer = $_SESSION['request_referer'];
	else
		$referrer = isset($_SERVER['HTTP_REFERER']) ? @parse_url($_SERVER['HTTP_REFERER']) : array();

	// Check the refer but if we have CORS enabled and it came from a trusted source, we can skip this check.
	if (!empty($referrer['host']) && (empty($modSettings['allow_cors']) || empty($context['valid_cors_found']) || !in_array($context['valid_cors_found'], array('same', 'subdomain'))))
	{
		if (strpos($_SERVER['HTTP_HOST'], ':') !== false)
			$real_host = substr($_SERVER['HTTP_HOST'], 0, strpos($_SERVER['HTTP_HOST'], ':'));
		else
			$real_host = $_SERVER['HTTP_HOST'];

		$parsed_url = parse_iri($boardurl);

		// Are global cookies on?  If so, let's check them ;).
		if (!empty($modSettings['globalCookies']))
		{
			if (preg_match('~(?:[^\.]+\.)?([^\.]{3,}\..+)\z~i', $parsed_url['host'], $parts) == 1)
				$parsed_url['host'] = $parts[1];

			if (preg_match('~(?:[^\.]+\.)?([^\.]{3,}\..+)\z~i', $referrer['host'], $parts) == 1)
				$referrer['host'] = $parts[1];

			if (preg_match('~(?:[^\.]+\.)?([^\.]{3,}\..+)\z~i', $real_host, $parts) == 1)
				$real_host = $parts[1];
		}

		// Okay: referrer must either match parsed_url or real_host.
		if (isset($parsed_url['host']) && strtolower($referrer['host']) != strtolower($parsed_url['host']) && strtolower($referrer['host']) != strtolower($real_host))
		{
			$error = 'verify_url_fail';
			$log_error = true;
		}
	}

	// Well, first of all, if a from_action is specified you'd better have an old_url.
	if (!empty($from_action) && (!isset($_SESSION['old_url']) || preg_match('~[?;&]action=' . $from_action . '([;&]|$)~', $_SESSION['old_url']) == 0))
	{
		$error = 'verify_url_fail';
		$log_error = true;
	}

	if (strtolower($_SERVER['HTTP_USER_AGENT']) == 'hacker')
		fatal_error('Sound the alarm!  It\'s a hacker!  Close the castle gates!!', false);

	// Everything is ok, return an empty string.
	if (!isset($error))
		return '';
	// A session error occurred, show the error.
	elseif ($is_fatal)
	{
		if (isset($_GET['xml']))
		{
			ob_end_clean();
			send_http_status(403, 'Forbidden - Session timeout');
			die;
		}
		else
			fatal_lang_error($error, isset($log_error) ? 'user' : false);
	}
	// A session error occurred, return the error to the calling function.
	else
		return $error;

	// We really should never fall through here, for very important reasons.  Let's make sure.
	trigger_error('No direct access...', E_USER_ERROR);
}

/**
 * Check if a specific confirm parameter was given.
 *
 * @param string $action The action we want to check against
 * @return bool|string True if the check passed or a token
 */
function checkConfirm($action)
{
	global $modSettings, $smcFunc;

	if (isset($_GET['confirm']) && isset($_SESSION['confirm_' . $action]) && md5($_GET['confirm'] . $_SERVER['HTTP_USER_AGENT']) == $_SESSION['confirm_' . $action])
		return true;

	else
	{
		$token = md5($smcFunc['random_int']() . session_id() . (string) microtime() . $modSettings['rand_seed']);
		$_SESSION['confirm_' . $action] = md5($token . $_SERVER['HTTP_USER_AGENT']);

		return $token;
	}
}

/**
 * Lets give you a token of our appreciation.
 *
 * @param string $action The action to create the token for
 * @param string $type The type of token ('post', 'get' or 'request')
 * @return array An array containing the name of the token var and the actual token
 */
function createToken($action, $type = 'post')
{
	global $modSettings, $context, $smcFunc;

	$token = md5($smcFunc['random_int']() . session_id() . (string) microtime() . $modSettings['rand_seed'] . $type);
	$token_var = substr(preg_replace('~^\d+~', '', md5($smcFunc['random_int']() . (string) microtime() . $smcFunc['random_int']())), 0, $smcFunc['random_int'](7, 12));

	$_SESSION['token'][$type . '-' . $action] = array($token_var, md5($token . $_SERVER['HTTP_USER_AGENT']), time(), $token);

	$context[$action . '_token'] = $token;
	$context[$action . '_token_var'] = $token_var;

	return array($action . '_token_var' => $token_var, $action . '_token' => $token);
}

/**
 * Only patrons with valid tokens can ride this ride.
 *
 * @param string $action The action to validate the token for
 * @param string $type The type of request (get, request, or post)
 * @param bool $reset Whether to reset the token and display an error if validation fails
 * @return bool returns whether the validation was successful
 */
function validateToken($action, $type = 'post', $reset = true)
{
	$type = $type == 'get' || $type == 'request' ? $type : 'post';

	// This nasty piece of code validates a token.
	/*
		1. The token exists in session.
		2. The {$type} variable should exist.
		3. We concat the variable we received with the user agent
		4. Match that result against what is in the session.
		5. If it matches, success, otherwise we fallout.
	*/
	if (isset($_SESSION['token'][$type . '-' . $action], $GLOBALS['_' . strtoupper($type)][$_SESSION['token'][$type . '-' . $action][0]]) && md5($GLOBALS['_' . strtoupper($type)][$_SESSION['token'][$type . '-' . $action][0]] . $_SERVER['HTTP_USER_AGENT']) === $_SESSION['token'][$type . '-' . $action][1])
	{
		// Invalidate this token now.
		unset($_SESSION['token'][$type . '-' . $action]);

		return true;
	}

	// Patrons with invalid tokens get the boot.
	if ($reset)
	{
		// Might as well do some cleanup on this.
		cleanTokens();

		// I'm back baby.
		createToken($action, $type);

		fatal_lang_error('token_verify_fail', false);
	}
	// Remove this token as its useless
	else
		unset($_SESSION['token'][$type . '-' . $action]);

	// Randomly check if we should remove some older tokens.
	if (mt_rand(0, 138) == 23)
		cleanTokens();

	return false;
}

/**
 * Removes old unused tokens from session
 * defaults to 3 hours before a token is considered expired
 * if $complete = true will remove all tokens
 *
 * @param bool $complete Whether to remove all tokens or only expired ones
 */
function cleanTokens($complete = false)
{
	// We appreciate cleaning up after yourselves.
	if (!isset($_SESSION['token']))
		return;

	// Clean up tokens, trying to give enough time still.
	foreach ($_SESSION['token'] as $key => $data)
		if ($data[2] + 10800 < time() || $complete)
			unset($_SESSION['token'][$key]);
}

/**
 * Check whether a form has been submitted twice.
 * Registers a sequence number for a form.
 * Checks whether a submitted sequence number is registered in the current session.
 * Depending on the value of is_fatal shows an error or returns true or false.
 * Frees a sequence number from the stack after it's been checked.
 * Frees a sequence number without checking if action == 'free'.
 *
 * @param string $action The action - can be 'register', 'check' or 'free'
 * @param bool $is_fatal Whether to die with a fatal error
 * @return void|bool If the action isn't check, returns nothing, otherwise returns whether the check was successful
 */
function checkSubmitOnce($action, $is_fatal = true)
{
	global $context, $txt;

	if (!isset($_SESSION['forms']))
		$_SESSION['forms'] = array();

	// Register a form number and store it in the session stack. (use this on the page that has the form.)
	if ($action == 'register')
	{
		$context['form_sequence_number'] = 0;
		while (empty($context['form_sequence_number']) || in_array($context['form_sequence_number'], $_SESSION['forms']))
			$context['form_sequence_number'] = mt_rand(1, 16000000);
	}
	// Check whether the submitted number can be found in the session.
	elseif ($action == 'check')
	{
		if (!isset($_REQUEST['seqnum']))
			return true;
		elseif (!in_array($_REQUEST['seqnum'], $_SESSION['forms']))
		{
			$_SESSION['forms'][] = (int) $_REQUEST['seqnum'];
			return true;
		}
		elseif ($is_fatal)
			fatal_lang_error('error_form_already_submitted', false);
		else
			return false;
	}
	// Don't check, just free the stack number.
	elseif ($action == 'free' && isset($_REQUEST['seqnum']) && in_array($_REQUEST['seqnum'], $_SESSION['forms']))
		$_SESSION['forms'] = array_diff($_SESSION['forms'], array($_REQUEST['seqnum']));
	elseif ($action != 'free')
	{
		loadLanguage('Errors');
		trigger_error(sprintf($txt['check_submit_once_invalid_action'], $action), E_USER_WARNING);
	}
}

/**
 * Check the user's permissions.
 * checks whether the user is allowed to do permission. (ie. post_new.)
 * If boards is specified, checks those boards instead of the current one.
 * If any is true, will return true if the user has the permission on any of the specified boards
 * Always returns true if the user is an administrator.
 *
 * @param string|array $permission A single permission to check or an array of permissions to check
 * @param int|array $boards The ID of a board or an array of board IDs if we want to check board-level permissions
 * @param bool $any Whether to check for permission on at least one board instead of all boards
 * @return bool Whether the user has the specified permission
 */
function allowedTo($permission, $boards = null, $any = false)
{
	global $user_info, $smcFunc;
	static $perm_cache = array();

	// You're always allowed to do nothing. (unless you're a working man, MR. LAZY :P!)
	if (empty($permission))
		return true;

	// You're never allowed to do something if your data hasn't been loaded yet!
	if (empty($user_info) || !isset($user_info['permissions']))
		return false;

	// Administrators are supermen :P.
	if ($user_info['is_admin'])
		return true;

	// Let's ensure this is an array.
	$permission = (array) $permission;

	// This should be a boolean.
	$any = (bool) $any;

	// Are we checking the _current_ board, or some other boards?
	if ($boards === null)
	{
		$user_permissions = (array) $user_info['permissions'];

		// Allow temporary overrides for general permissions?
		call_integration_hook('integrate_allowed_to_general', array(&$user_permissions, $permission));

		return array_intersect($permission, $user_permissions) != [];
	}
	elseif (!is_array($boards))
		$boards = array($boards);

	$cache_key = hash('md5', $user_info['id'] . '-' . implode(',', $permission) . '-' . implode(',', $boards) . '-' . (int) $any);

	if (isset($perm_cache[$cache_key]))
		return $perm_cache[$cache_key];

	$request = $smcFunc['db_query']('', '
		SELECT MIN(bp.add_deny) AS add_deny
		FROM {db_prefix}boards AS b
			INNER JOIN {db_prefix}board_permissions AS bp ON (bp.id_profile = b.id_profile)
			LEFT JOIN {db_prefix}moderators AS mods ON (mods.id_board = b.id_board AND mods.id_member = {int:current_member})
			LEFT JOIN {db_prefix}moderator_groups AS modgs ON (modgs.id_board = b.id_board AND modgs.id_group IN ({array_int:group_list}))
		WHERE b.id_board IN ({array_int:board_list})
			AND bp.id_group IN ({array_int:group_list}, {int:moderator_group})
			AND bp.permission IN ({array_string:permission_list})
			AND (mods.id_member IS NOT NULL OR modgs.id_group IS NOT NULL OR bp.id_group != {int:moderator_group})
		GROUP BY b.id_board',
		array(
			'current_member' => $user_info['id'],
			'board_list' => $boards,
			'group_list' => $user_info['groups'],
			'moderator_group' => 3,
			'permission_list' => $permission,
		)
	);

	if ($any)
	{
		$result = false;
		while ($row = $smcFunc['db_fetch_assoc']($request))
		{
			$result = !empty($row['add_deny']);
			if ($result == true)
				break;
		}
		$smcFunc['db_free_result']($request);
		$return = $result;
	}

	// Make sure they can do it on all of the boards.
	elseif ($smcFunc['db_num_rows']($request) != count($boards))
		$return = false;

	else
	{
		$result = true;
		while ($row = $smcFunc['db_fetch_assoc']($request))
			$result &= !empty($row['add_deny']);
		$smcFunc['db_free_result']($request);
		$return = $result;
	}

	// Allow temporary overrides for board permissions?
	call_integration_hook('integrate_allowed_to_board', array(&$return, $permission, $boards, $any));

	$perm_cache[$cache_key] = $return;

	// If the query returned 1, they can do it... otherwise, they can't.
	return $return;
}

/**
 * Fatal error if they cannot.
 * Uses allowedTo() to check if the user is allowed to do permission.
 * Checks the passed boards or current board for the permission.
 * If $any is true, the user only needs permission on at least one of the boards to pass
 * If they are not, it loads the Errors language file and shows an error using $txt['cannot_' . $permission].
 * If they are a guest and cannot do it, this calls is_not_guest().
 *
 * @param string|array $permission A single permission to check or an array of permissions to check
 * @param int|array $boards The ID of a single board or an array of board IDs if we're checking board-level permissions (null otherwise)
 * @param bool $any Whether to check for permission on at least one board instead of all boards
 */
function isAllowedTo($permission, $boards = null, $any = false)
{
	global $user_info, $txt;

	$heavy_permissions = array(
		'admin_forum',
		'manage_attachments',
		'manage_smileys',
		'manage_boards',
		'edit_news',
		'moderate_forum',
		'manage_bans',
		'manage_membergroups',
		'manage_permissions',
	);

	// Make it an array, even if a string was passed.
	$permission = (array) $permission;

	call_integration_hook('integrate_heavy_permissions_session', array(&$heavy_permissions));

	// Check the permission and return an error...
	if (!allowedTo($permission, $boards, $any))
	{
		// Pick the last array entry as the permission shown as the error.
		$error_permission = array_shift($permission);

		// If they are a guest, show a login. (because the error might be gone if they do!)
		if ($user_info['is_guest'])
		{
			loadLanguage('Errors');
			is_not_guest($txt['cannot_' . $error_permission]);
		}

		// Clear the action because they aren't really doing that!
		$_GET['action'] = '';
		$_GET['board'] = '';
		$_GET['topic'] = '';
		writeLog(true);

		fatal_lang_error('cannot_' . $error_permission, false);

		// Getting this far is a really big problem, but let's try our best to prevent any cases...
		trigger_error('No direct access...', E_USER_ERROR);
	}

	// If you're doing something on behalf of some "heavy" permissions, validate your session.
	// (take out the heavy permissions, and if you can't do anything but those, you need a validated session.)
	if (!allowedTo(array_diff($permission, $heavy_permissions), $boards))
		validateSession();
}

/**
 * Return the boards a user has a certain (board) permission on. (array(0) if all.)
 *  - returns a list of boards on which the user is allowed to do the specified permission.
 *  - returns an array with only a 0 in it if the user has permission to do this on every board.
 *  - returns an empty array if he or she cannot do this on any board.
 * If check_access is true will also make sure the group has proper access to that board.
 *
 * @param string|array $permissions A single permission to check or an array of permissions to check
 * @param bool $check_access Whether to check only the boards the user has access to
 * @param bool $simple Whether to return a simple array of board IDs or one with permissions as the keys
 * @return array An array of board IDs or an array containing 'permission' => 'board,board2,...' pairs
 */
function boardsAllowedTo($permissions, $check_access = true, $simple = true)
{
	global $user_info, $smcFunc;

	// Arrays are nice, most of the time.
	$permissions = (array) $permissions;

	/*
	 * Set $simple to true to use this function as it were in SMF 2.0.x.
	 * Otherwise, the resultant array becomes split into the multiple
	 * permissions that were passed. Other than that, it's just the normal
	 * state of play that you're used to.
	 */

	// Administrators are all powerful, sorry.
	if ($user_info['is_admin'])
	{
		if ($simple)
			return array(0);
		else
		{
			$boards = array();
			foreach ($permissions as $permission)
				$boards[$permission] = array(0);

			return $boards;
		}
	}

	// All groups the user is in except 'moderator'.
	$groups = array_diff($user_info['groups'], array(3));

	$request = $smcFunc['db_query']('', '
		SELECT b.id_board, bp.add_deny' . ($simple ? '' : ', bp.permission') . '
		FROM {db_prefix}board_permissions AS bp
			INNER JOIN {db_prefix}boards AS b ON (b.id_profile = bp.id_profile)
			LEFT JOIN {db_prefix}moderators AS mods ON (mods.id_board = b.id_board AND mods.id_member = {int:current_member})
			LEFT JOIN {db_prefix}moderator_groups AS modgs ON (modgs.id_board = b.id_board AND modgs.id_group IN ({array_int:group_list}))
		WHERE bp.id_group IN ({array_int:group_list}, {int:moderator_group})
			AND bp.permission IN ({array_string:permissions})
			AND (mods.id_member IS NOT NULL OR modgs.id_group IS NOT NULL OR bp.id_group != {int:moderator_group})' .
			($check_access ? ' AND {query_see_board}' : ''),
		array(
			'current_member' => $user_info['id'],
			'group_list' => $groups,
			'moderator_group' => 3,
			'permissions' => $permissions,
		)
	);
	$boards = array();
	$deny_boards = array();
	while ($row = $smcFunc['db_fetch_assoc']($request))
	{
		if ($simple)
		{
			if (empty($row['add_deny']))
				$deny_boards[] = $row['id_board'];
			else
				$boards[] = $row['id_board'];
		}
		else
		{
			if (empty($row['add_deny']))
				$deny_boards[$row['permission']][] = $row['id_board'];
			else
				$boards[$row['permission']][] = $row['id_board'];
		}
	}
	$smcFunc['db_free_result']($request);

	if ($simple)
		$boards = array_unique(array_values(array_diff($boards, $deny_boards)));
	else
	{
		foreach ($permissions as $permission)
		{
			// never had it to start with
			if (empty($boards[$permission]))
				$boards[$permission] = array();
			else
			{
				// Or it may have been removed
				$deny_boards[$permission] = isset($deny_boards[$permission]) ? $deny_boards[$permission] : array();
				$boards[$permission] = array_unique(array_values(array_diff($boards[$permission], $deny_boards[$permission])));
			}
		}
	}

	// Maybe a mod needs to tweak the list of allowed boards on the fly?
	call_integration_hook('integrate_boards_allowed_to', array(&$boards, $deny_boards, $permissions, $check_access, $simple));

	return $boards;
}

/**
 * This function attempts to protect from spammed messages and the like.
 * The time taken depends on error_type - generally uses the modSetting.
 *
 * @param string $error_type The error type. Also used as a $txt index (not an actual string).
 * @param boolean $only_return_result Whether you want the function to die with a fatal_lang_error.
 * @return bool Whether they've posted within the limit
 */
function spamProtection($error_type, $only_return_result = false)
{
	global $modSettings, $user_info, $smcFunc;

	// Certain types take less/more time.
	$timeOverrides = array(
		'login' => 2,
		'register' => 2,
		'remind' => 30,
		'sendmail' => $modSettings['spamWaitTime'] * 5,
		'reporttm' => $modSettings['spamWaitTime'] * 4,
		'search' => !empty($modSettings['search_floodcontrol_time']) ? $modSettings['search_floodcontrol_time'] : 1,
	);

	call_integration_hook('integrate_spam_protection', array(&$timeOverrides));

	// Moderators are free...
	if (!allowedTo('moderate_board'))
		$timeLimit = isset($timeOverrides[$error_type]) ? $timeOverrides[$error_type] : $modSettings['spamWaitTime'];
	else
		$timeLimit = 2;

	// Delete old entries...
	$smcFunc['db_query']('', '
		DELETE FROM {db_prefix}log_floodcontrol
		WHERE log_time < {int:log_time}
			AND log_type = {string:log_type}',
		array(
			'log_time' => time() - $timeLimit,
			'log_type' => $error_type,
		)
	);

	// Add a new entry, deleting the old if necessary.
	$smcFunc['db_insert']('replace',
		'{db_prefix}log_floodcontrol',
		array('ip' => 'inet', 'log_time' => 'int', 'log_type' => 'string'),
		array($user_info['ip'], time(), $error_type),
		array('ip', 'log_type')
	);

	// If affected is 0 or 2, it was there already.
	if ($smcFunc['db_affected_rows']() != 1)
	{
		// Spammer!  You only have to wait a *few* seconds!
		if (!$only_return_result)
			fatal_lang_error($error_type . '_WaitTime_broken', false, array($timeLimit));

		return true;
	}

	// They haven't posted within the limit.
	return false;
}

/**
 * A generic function to create a pair of index.php and .htaccess files in a directory
 *
 * @param string|array $paths The (absolute) directory path
 * @param boolean $attachments Whether this is an attachment directory
 * @return bool|array True on success an array of errors if anything fails
 */
function secureDirectory($paths, $attachments = false)
{
	$errors = array();

	// Work with arrays
	$paths = (array) $paths;

	if (empty($paths))
		$errors[] = 'empty_path';

	if (!empty($errors))
		return $errors;

	foreach ($paths as $path)
	{
		if (!is_writable($path))
		{
			$errors[] = 'path_not_writable';

			continue;
		}

		$directory_name = basename($path);

		$close = empty($attachments) ? '
</Files>' : '
	Allow from localhost
</Files>

RemoveHandler .php .php3 .phtml .cgi .fcgi .pl .fpl .shtml';

		if (file_exists($path . '/.htaccess'))
		{
			$errors[] = 'htaccess_exists';

			continue;
		}

		else
		{
			$fh = @fopen($path . '/.htaccess', 'w');

			if ($fh)
			{
				fwrite($fh, '<Files *>
	Order Deny,Allow
	Deny from all' . $close);
				fclose($fh);
			}

			else
				$errors[] = 'htaccess_cannot_create_file';
		}

		if (file_exists($path . '/index.php'))
		{
			$errors[] = 'index-php_exists';

			continue;
		}

		else
		{
			$fh = @fopen($path . '/index.php', 'w');

			if ($fh)
			{
				fwrite($fh, '<' . '?php

/**
 * This file is here solely to protect your ' . $directory_name . ' directory.
 */

// Look for Settings.php....
if (file_exists(dirname(dirname(__FILE__)) . \'/Settings.php\'))
{
	// Found it!
	require(dirname(dirname(__FILE__)) . \'/Settings.php\');
	header(\'location: \' . $boardurl);
}
// Can\'t find it... just forget it.
else
	exit;

?' . '>');
				fclose($fh);
			}

			else
				$errors[] = 'index-php_cannot_create_file';
		}
	}

	if (!empty($errors))
		return $errors;

	else
		return true;
}

/**
 * This sets the X-Frame-Options header.
 *
 * @param string $override An option to override (either 'SAMEORIGIN' or 'DENY')
 * @since 2.1
 */
function frameOptionsHeader($override = null)
{
	global $modSettings;

	$option = 'SAMEORIGIN';
	if (is_null($override) && !empty($modSettings['frame_security']))
		$option = $modSettings['frame_security'];
	elseif (in_array($override, array('SAMEORIGIN', 'DENY')))
		$option = $override;

	// Don't bother setting the header if we have disabled it.
	if ($option == 'DISABLE')
		return;

	// Finally set it.
	header('x-frame-options: ' . $option);

	// And some other useful ones.
	header('x-xss-protection: 1');
	header('x-content-type-options: nosniff');
}

/**
 * This sets the Access-Control-Allow-Origin header.
 * @link https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
 *
 * @param bool $set_header (Default: true): When false, we will do the logic, but not send the headers.  The relevant logic is still saved in the $context and can be sent manually.
 *
 * @since 2.1
 */
function corsPolicyHeader($set_header = true)
{
	global $boardurl, $modSettings, $context;

	if (empty($modSettings['allow_cors']) || empty($_SERVER['HTTP_ORIGIN']))
		return;

	foreach (array('origin' => $_SERVER['HTTP_ORIGIN'], 'boardurl_parts' => $boardurl) as $var => $url)
	{
		// Convert any Punycode to Unicode for the sake of comparision, then parse.
		$$var = parse_iri(url_to_iri((string) validate_iri(normalize_iri(trim($url)))));
	}

	// The admin wants weak security... :(
	if (!empty($modSettings['cors_domains']) && $modSettings['cors_domains'] === '*')
	{
		$context['cors_domain'] = '*';
		$context['valid_cors_found'] = 'wildcard';
	}

	// Oh good, the admin cares about security. :)
	else
	{
		$i = 0;

		// Build our list of allowed CORS origins.
		$allowed_origins = array();

		// If subdomain-independent cookies are on, allow CORS requests from subdomains.
		if (!empty($modSettings['globalCookies']) && !empty($modSettings['globalCookiesDomain']))
		{
			$allowed_origins[++$i] = array_merge(parse_iri('//*.' . trim($modSettings['globalCookiesDomain'])), array('type' => 'subdomain'));
		}

		// Support forum_alias_urls as well, since those are supported by our login cookie.
		if (!empty($modSettings['forum_alias_urls']))
		{
			foreach (explode(',', $modSettings['forum_alias_urls']) as $alias)
				$allowed_origins[++$i] = array_merge(parse_iri((strpos($alias, '//') === false ? '//' : '') . trim($alias)), array('type' => 'alias'));
		}

		// Additional CORS domains.
		if (!empty($modSettings['cors_domains']))
		{
			foreach (explode(',', $modSettings['cors_domains']) as $cors_domain)
			{
				$allowed_origins[++$i] = array_merge(parse_iri((strpos($cors_domain, '//') === false ? '//' : '') . trim($cors_domain)), array('type' => 'additional'));

				if (strpos($allowed_origins[$i]['host'], '*') === 0)
					 $allowed_origins[$i]['type'] .= '_wildcard';
			}
		}

		// Does the origin match any of our allowed domains?
		foreach ($allowed_origins as $allowed_origin)
		{
			// If a specific scheme is required, it must match.
			if (!empty($allowed_origin['scheme']) && $allowed_origin['scheme'] !== $origin['scheme'])
				continue;

			// If a specific port is required, it must match.
			if (!empty($allowed_origin['port']))
			{
				// Automatically supply the default port for the "special" schemes.
				// See https://url.spec.whatwg.org/#special-scheme
				if (empty($origin['port']))
				{
					switch ($origin['scheme'])
					{
						case 'http':
						case 'ws':
							$origin['port'] = 80;
							break;

						case 'https':
						case 'wss':
							$origin['port'] = 443;
							break;

						case 'ftp':
							$origin['port'] = 21;
							break;

						case 'file':
						default:
							$origin['port'] = null;
							break;
					}
				}

				if ((int) $allowed_origin['port'] !== (int) $origin['port'])
					continue;
			}

			// Wildcard can only be the first character.
			if (strrpos($allowed_origin['host'], '*') > 0)
				continue;

			// Wildcard means allow the domain or any subdomains.
			if (strpos($allowed_origin['host'], '*') === 0)
				$host_regex = '(?:^|\.)' . preg_quote(ltrim($allowed_origin['host'], '*.'), '~') . '$';

			// No wildcard means allow the domain only.
			else
				$host_regex = '^' . preg_quote($allowed_origin['host'], '~') . '$';

			if (preg_match('~' . $host_regex . '~u', $origin['host']))
			{
				$context['cors_domain'] = trim($_SERVER['HTTP_ORIGIN']);
				$context['valid_cors_found'] = $allowed_origin['type'];
				break;
			}
		}
	}

	// The default is just to place the root URL of the forum into the policy.
	if (empty($context['cors_domain']))
	{
		$context['cors_domain'] = iri_to_url($boardurl_parts['scheme'] . '://' . $boardurl_parts['host']);

		// Attach the port if needed.
		if (!empty($boardurl_parts['port']))
			$context['cors_domain'] .= ':' . $boardurl_parts['port'];

		$context['valid_cors_found'] = 'same';
	}

	$context['cors_headers'] = 'X-SMF-AJAX';

	// Any additional headers?
	if (!empty($modSettings['cors_headers']))
	{
		// Cleanup any typos.
		$cors_headers = explode(',', $modSettings['cors_headers']);
		foreach ($cors_headers as &$ch)
			$ch = str_replace(' ', '-', trim($ch));

		$context['cors_headers'] .= ',' . implode(',', $cors_headers);
	}

	// Allowing Cross-Origin Resource Sharing (CORS).
	if ($set_header && !empty($context['valid_cors_found']) && !empty($context['cors_domain']))
	{
		header('Access-Control-Allow-Origin: ' . $context['cors_domain']);
		header('Access-Control-Allow-Headers: ' . $context['cors_headers']);

		// Be careful with this, you're allowing an external site to allow the browser to send cookies with this.
		if (!empty($modSettings['allow_cors_credentials']))
			header('Access-Control-Allow-Credentials: true');
	}
}

?>