<?php
/**
 * @file include/security.php
 */

use Friendica\Core\Addon;
use Friendica\Core\Config;
use Friendica\Core\L10n;
use Friendica\Core\PConfig;
use Friendica\Core\System;
use Friendica\Database\DBA;
use Friendica\Model\Contact;
use Friendica\Model\Group;
use Friendica\Util\DateTimeFormat;

/**
 * @brief Calculate the hash that is needed for the "Friendica" cookie
 *
 * @param array $user Record from "user" table
 *
 * @return string Hashed data
 */
function cookie_hash($user)
{
	return(hash("sha256", Config::get("system", "site_prvkey") .
			$user["prvkey"] .
			$user["password"]));
}

/**
 * @brief Set the "Friendica" cookie
 *
 * @param int $time
 * @param array $user Record from "user" table
 */
function new_cookie($time, $user = [])
{
	if ($time != 0) {
		$time = $time + time();
	}

	if ($user) {
		$value = json_encode(["uid" => $user["uid"],
			"hash" => cookie_hash($user),
			"ip" => defaults($_SERVER, 'REMOTE_ADDR', '0.0.0.0')]);
	} else {
		$value = "";
	}

	setcookie("Friendica", $value, $time, "/", "", (Config::get('system', 'ssl_policy') == SSL_POLICY_FULL), true);
}

/**
 * @brief Sets the provided user's authenticated session
 *
 * @todo Should be moved to Friendica\Core\Session once it's created
 *
 * @param type $user_record
 * @param type $login_initial
 * @param type $interactive
 * @param type $login_refresh
 */
function authenticate_success($user_record, $login_initial = false, $interactive = false, $login_refresh = false)
{
	$a = get_app();

	$_SESSION['uid'] = $user_record['uid'];
	$_SESSION['theme'] = $user_record['theme'];
	$_SESSION['mobile-theme'] = PConfig::get($user_record['uid'], 'system', 'mobile_theme');
	$_SESSION['authenticated'] = 1;
	$_SESSION['page_flags'] = $user_record['page-flags'];
	$_SESSION['my_url'] = System::baseUrl() . '/profile/' . $user_record['nickname'];
	$_SESSION['my_address'] = $user_record['nickname'] . '@' . substr(System::baseUrl(), strpos(System::baseUrl(), '://') + 3);
	$_SESSION['addr'] = defaults($_SERVER, 'REMOTE_ADDR', '0.0.0.0');

	$a->user = $user_record;

	if ($interactive) {
		if ($a->user['login_date'] <= NULL_DATE) {
			$_SESSION['return_url'] = 'profile_photo/new';
			$a->module = 'profile_photo';
			info(L10n::t("Welcome ") . $a->user['username'] . EOL);
			info(L10n::t('Please upload a profile photo.') . EOL);
		} else {
			info(L10n::t("Welcome back ") . $a->user['username'] . EOL);
		}
	}

	$member_since = strtotime($a->user['register_date']);
	if (time() < ($member_since + ( 60 * 60 * 24 * 14))) {
		$_SESSION['new_member'] = true;
	} else {
		$_SESSION['new_member'] = false;
	}
	if (strlen($a->user['timezone'])) {
		date_default_timezone_set($a->user['timezone']);
		$a->timezone = $a->user['timezone'];
	}

	$master_record = $a->user;

	if ((x($_SESSION, 'submanage')) && intval($_SESSION['submanage'])) {
		$user = DBA::selectFirst('user', [], ['uid' => $_SESSION['submanage']]);
		if (DBA::isResult($user)) {
			$master_record = $user;
		}
	}

	if ($master_record['parent-uid'] == 0) {
		// First add our own entry
		$a->identities = [['uid' => $master_record['uid'],
				'username' => $master_record['username'],
				'nickname' => $master_record['nickname']]];

		// Then add all the children
		$r = DBA::select('user', ['uid', 'username', 'nickname'],
			['parent-uid' => $master_record['uid'], 'account_removed' => false]);
		if (DBA::isResult($r)) {
			$a->identities = array_merge($a->identities, DBA::toArray($r));
		}
	} else {
		// Just ensure that the array is always defined
		$a->identities = [];

		// First entry is our parent
		$r = DBA::select('user', ['uid', 'username', 'nickname'],
			['uid' => $master_record['parent-uid'], 'account_removed' => false]);
		if (DBA::isResult($r)) {
			$a->identities = DBA::toArray($r);
		}

		// Then add all siblings
		$r = DBA::select('user', ['uid', 'username', 'nickname'],
			['parent-uid' => $master_record['parent-uid'], 'account_removed' => false]);
		if (DBA::isResult($r)) {
			$a->identities = array_merge($a->identities, DBA::toArray($r));
		}
	}

	$r = DBA::p("SELECT `user`.`uid`, `user`.`username`, `user`.`nickname`
		FROM `manage`
		INNER JOIN `user` ON `manage`.`mid` = `user`.`uid`
		WHERE `user`.`account_removed` = 0 AND `manage`.`uid` = ?",
		$master_record['uid']
	);
	if (DBA::isResult($r)) {
		$a->identities = array_merge($a->identities, DBA::toArray($r));
	}

	if ($login_initial) {
		logger('auth_identities: ' . print_r($a->identities, true), LOGGER_DEBUG);
	}
	if ($login_refresh) {
		logger('auth_identities refresh: ' . print_r($a->identities, true), LOGGER_DEBUG);
	}

	$contact = DBA::selectFirst('contact', [], ['uid' => $_SESSION['uid'], 'self' => true]);
	if (DBA::isResult($contact)) {
		$a->contact = $contact;
		$a->cid = $contact['id'];
		$_SESSION['cid'] = $a->cid;
	}

	header('X-Account-Management-Status: active; name="' . $a->user['username'] . '"; id="' . $a->user['nickname'] . '"');

	if ($login_initial || $login_refresh) {
		DBA::update('user', ['login_date' => DateTimeFormat::utcNow()], ['uid' => $_SESSION['uid']]);

		// Set the login date for all identities of the user
		DBA::update('user', ['login_date' => DateTimeFormat::utcNow()],
			['parent-uid' => $master_record['uid'], 'account_removed' => false]);
	}

	if ($login_initial) {
		/*
		 * If the user specified to remember the authentication, then set a cookie
		 * that expires after one week (the default is when the browser is closed).
		 * The cookie will be renewed automatically.
		 * The week ensures that sessions will expire after some inactivity.
		 */
		if ($_SESSION['remember']) {
			logger('Injecting cookie for remembered user ' . $a->user['nickname']);
			new_cookie(604800, $user_record);
			unset($_SESSION['remember']);
		}
	}

	if ($login_initial) {
		Addon::callHooks('logged_in', $a->user);

		if (($a->module !== 'home') && isset($_SESSION['return_url'])) {
			goaway(System::baseUrl() . '/' . $_SESSION['return_url']);
		}
	}
}

function can_write_wall($owner)
{
	static $verified = 0;

	if (!local_user() && !remote_user()) {
		return false;
	}

	$uid = local_user();
	if ($uid == $owner) {
		return true;
	}

	if (local_user() && ($owner == 0)) {
		return true;
	}

	if (remote_user()) {
		// use remembered decision and avoid a DB lookup for each and every display item
		// DO NOT use this function if there are going to be multiple owners
		// We have a contact-id for an authenticated remote user, this block determines if the contact
		// belongs to this page owner, and has the necessary permissions to post content

		if ($verified === 2) {
			return true;
		} elseif ($verified === 1) {
			return false;
		} else {
			$cid = 0;

			if (is_array($_SESSION['remote'])) {
				foreach ($_SESSION['remote'] as $visitor) {
					if ($visitor['uid'] == $owner) {
						$cid = $visitor['cid'];
						break;
					}
				}
			}

			if (!$cid) {
				return false;
			}

			$r = q("SELECT `contact`.*, `user`.`page-flags` FROM `contact` INNER JOIN `user` on `user`.`uid` = `contact`.`uid`
				WHERE `contact`.`uid` = %d AND `contact`.`id` = %d AND `contact`.`blocked` = 0 AND `contact`.`pending` = 0
				AND `user`.`blockwall` = 0 AND `readonly` = 0  AND ( `contact`.`rel` IN ( %d , %d ) OR `user`.`page-flags` = %d ) LIMIT 1",
				intval($owner),
				intval($cid),
				intval(Contact::SHARING),
				intval(Contact::FRIEND),
				intval(PAGE_COMMUNITY)
			);

			if (DBA::isResult($r)) {
				$verified = 2;
				return true;
			} else {
				$verified = 1;
			}
		}
	}

	return false;
}

/// @TODO $groups should be array
function permissions_sql($owner_id, $remote_verified = false, $groups = null)
{
	$local_user = local_user();
	$remote_user = remote_user();

	/**
	 * Construct permissions
	 *
	 * default permissions - anonymous user
	 */
	$sql = " AND allow_cid = ''
			 AND allow_gid = ''
			 AND deny_cid  = ''
			 AND deny_gid  = ''
	";

	/**
	 * Profile owner - everything is visible
	 */
	if ($local_user && $local_user == $owner_id) {
		$sql = '';
	/**
	 * Authenticated visitor. Unless pre-verified,
	 * check that the contact belongs to this $owner_id
	 * and load the groups the visitor belongs to.
	 * If pre-verified, the caller is expected to have already
	 * done this and passed the groups into this function.
	 */
	} elseif ($remote_user) {
		/*
		 * Authenticated visitor. Unless pre-verified,
		 * check that the contact belongs to this $owner_id
		 * and load the groups the visitor belongs to.
		 * If pre-verified, the caller is expected to have already
		 * done this and passed the groups into this function.
		 */

		if (!$remote_verified) {
			$r = q("SELECT id FROM contact WHERE id = %d AND uid = %d AND blocked = 0 LIMIT 1",
				intval($remote_user),
				intval($owner_id)
			);
			if (DBA::isResult($r)) {
				$remote_verified = true;
				$groups = Group::getIdsByContactId($remote_user);
			}
		}

		if ($remote_verified) {
			$gs = '<<>>'; // should be impossible to match

			if (is_array($groups)) {
				foreach ($groups as $g) {
					$gs .= '|<' . intval($g) . '>';
				}
			}

			$sql = sprintf(
				" AND ( NOT (deny_cid REGEXP '<%d>' OR deny_gid REGEXP '%s')
				  AND ( allow_cid REGEXP '<%d>' OR allow_gid REGEXP '%s' OR ( allow_cid = '' AND allow_gid = '') )
				  )
				",
				intval($remote_user),
				DBA::escape($gs),
				intval($remote_user),
				DBA::escape($gs)
			);
		}
	}
	return $sql;
}

function item_permissions_sql($owner_id, $remote_verified = false, $groups = null)
{
	$local_user = local_user();
	$remote_user = remote_user();

	/*
	 * Construct permissions
	 *
	 * default permissions - anonymous user
	 */
	$sql = " AND `item`.allow_cid = ''
			 AND `item`.allow_gid = ''
			 AND `item`.deny_cid  = ''
			 AND `item`.deny_gid  = ''
			 AND `item`.private != 1
	";

	// Profile owner - everything is visible
	if ($local_user && ($local_user == $owner_id)) {
		$sql = '';
	} elseif ($remote_user) {
		/*
		 * Authenticated visitor. Unless pre-verified,
		 * check that the contact belongs to this $owner_id
		 * and load the groups the visitor belongs to.
		 * If pre-verified, the caller is expected to have already
		 * done this and passed the groups into this function.
		 */
		if (!$remote_verified) {
			$r = q("SELECT id FROM contact WHERE id = %d AND uid = %d AND blocked = 0 LIMIT 1",
				intval($remote_user),
				intval($owner_id)
			);
			if (DBA::isResult($r)) {
				$remote_verified = true;
				$groups = Group::getIdsByContactId($remote_user);
			}
		}
		if ($remote_verified) {

			$gs = '<<>>'; // should be impossible to match

			if (is_array($groups) && count($groups)) {
				foreach ($groups as $g) {
					$gs .= '|<' . intval($g) . '>';
				}
			}

			$sql = sprintf(
				" AND ( `item`.private = 0 OR ( `item`.private in (1,2) AND `item`.`wall` = 1
				  AND ( NOT (`item`.deny_cid REGEXP '<%d>' OR `item`.deny_gid REGEXP '%s')
				  AND ( `item`.allow_cid REGEXP '<%d>' OR `item`.allow_gid REGEXP '%s' OR ( `item`.allow_cid = '' AND `item`.allow_gid = '')))))
				",
				intval($remote_user),
				DBA::escape($gs),
				intval($remote_user),
				DBA::escape($gs)
			);
		}
	}

	return $sql;
}

/*
 * Functions used to protect against Cross-Site Request Forgery
 * The security token has to base on at least one value that an attacker can't know - here it's the session ID and the private key.
 * In this implementation, a security token is reusable (if the user submits a form, goes back and resubmits the form, maybe with small changes;
 * or if the security token is used for ajax-calls that happen several times), but only valid for a certain amout of time (3hours).
 * The "typename" seperates the security tokens of different types of forms. This could be relevant in the following case:
 *    A security token is used to protekt a link from CSRF (e.g. the "delete this profile"-link).
 *    If the new page contains by any chance external elements, then the used security token is exposed by the referrer.
 *    Actually, important actions should not be triggered by Links / GET-Requests at all, but somethimes they still are,
 *    so this mechanism brings in some damage control (the attacker would be able to forge a request to a form of this type, but not to forms of other types).
 */
function get_form_security_token($typename = '')
{
	$a = get_app();

	$timestamp = time();
	$sec_hash = hash('whirlpool', $a->user['guid'] . $a->user['prvkey'] . session_id() . $timestamp . $typename);

	return $timestamp . '.' . $sec_hash;
}

function check_form_security_token($typename = '', $formname = 'form_security_token')
{
	$hash = null;

	if (!empty($_REQUEST[$formname])) {
		/// @TODO Careful, not secured!
		$hash = $_REQUEST[$formname];
	}

	if (!empty($_SERVER['HTTP_X_CSRF_TOKEN'])) {
		/// @TODO Careful, not secured!
		$hash = $_SERVER['HTTP_X_CSRF_TOKEN'];
	}

	if (empty($hash)) {
		return false;
	}

	$max_livetime = 10800; // 3 hours

	$a = get_app();

	$x = explode('.', $hash);
	if (time() > (IntVal($x[0]) + $max_livetime)) {
		return false;
	}

	$sec_hash = hash('whirlpool', $a->user['guid'] . $a->user['prvkey'] . session_id() . $x[0] . $typename);

	return ($sec_hash == $x[1]);
}

function check_form_security_std_err_msg()
{
	return L10n::t("The form security token was not correct. This probably happened because the form has been opened for too long \x28>3 hours\x29 before submitting it.") . EOL;
}

function check_form_security_token_redirectOnErr($err_redirect, $typename = '', $formname = 'form_security_token')
{
	if (!check_form_security_token($typename, $formname)) {
		$a = get_app();
		logger('check_form_security_token failed: user ' . $a->user['guid'] . ' - form element ' . $typename);
		logger('check_form_security_token failed: _REQUEST data: ' . print_r($_REQUEST, true), LOGGER_DATA);
		notice(check_form_security_std_err_msg());
		goaway(System::baseUrl() . $err_redirect);
	}
}

function check_form_security_token_ForbiddenOnErr($typename = '', $formname = 'form_security_token')
{
	if (!check_form_security_token($typename, $formname)) {
		$a = get_app();
		logger('check_form_security_token failed: user ' . $a->user['guid'] . ' - form element ' . $typename);
		logger('check_form_security_token failed: _REQUEST data: ' . print_r($_REQUEST, true), LOGGER_DATA);
		header('HTTP/1.1 403 Forbidden');
		killme();
	}
}

/**
 * @brief Kills the "Friendica" cookie and all session data
 */
function nuke_session()
{
	new_cookie(-3600); // make sure cookie is deleted on browser close, as a security measure
	session_unset();
	session_destroy();
}