<?php
  
  /**

   * ownCloud – LDAP Connection

   *
   * @author Arthur Schiwon
   * @copyright 2012, 2013 Arthur Schiwon blizzz@owncloud.com
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
   * License as published by the Free Software Foundation; either
   * version 3 of the License, or any later version.
   *
   * This library 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 AFFERO GENERAL PUBLIC LICENSE for more details.
   *
   * You should have received a copy of the GNU Affero General Public
   * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
   *
   */
  
  namespace OCA\user_ldap\lib;

  class Connection extends LDAPUtility {

  	private $ldapConnectionRes = null;
  	private $configPrefix;
  	private $configID;
  	private $configured = false;
  
  	//whether connection should be kept on __destruct
  	private $dontDestruct = false;

  	private $hasPagedResultSupport = true;

  
  	//cache handler
  	protected $cache;

  	//settings handler
  	protected $configuration;
  
  	protected $doNotValidate = false;

  
  	/**
  	 * @brief Constructor
  	 * @param $configPrefix a string with the prefix for the configkey column (appconfig table)
  	 * @param $configID a string with the value for the appid column (appconfig table) or null for on-the-fly connections
  	 */

  	public function __construct(ILDAPWrapper $ldap, $configPrefix = '', $configID = 'user_ldap') {
  		parent::__construct($ldap);

  		$this->configPrefix = $configPrefix;
  		$this->configID = $configID;

  		$this->configuration = new Configuration($configPrefix);
  		$memcache = new \OC\Memcache\Factory();
  		if($memcache->isAvailable()) {
  			$this->cache = $memcache->create();
  		} else {
  			$this->cache = \OC_Cache::getGlobalCache();
  		}
  		$this->hasPagedResultSupport =
  			$this->ldap->hasPagedResultSupport();
  		$this->doNotValidate = !in_array($this->configPrefix,
  			Helper::getServerConfigurationPrefixes());

  	}
  
  	public function __destruct() {

  		if(!$this->dontDestruct &&
  			$this->ldap->isResource($this->ldapConnectionRes)) {
  			@$this->ldap->unbind($this->ldapConnectionRes);

  		};
  	}
  
  	/**
  	 * @brief defines behaviour when the instance is cloned
  	 */
  	public function __clone() {
  		//a cloned instance inherits the connection resource. It may use it,
  		//but it may not disconnect it
  		$this->dontDestruct = true;
  	}
  
  	public function __get($name) {
  		if(!$this->configured) {
  			$this->readConfiguration();
  		}

  		if($name === 'hasPagedResultSupport') {
  			return $this->hasPagedResultSupport;

  		}

  
  		return $this->configuration->$name;

  	}
  
  	public function __set($name, $value) {

  		$this->doNotValidate = false;
  		$before = $this->configuration->$name;
  		$this->configuration->$name = $value;
  		$after = $this->configuration->$name;
  		if($before !== $after) {

  			if(!empty($this->configID)) {

  				$this->configuration->saveConfiguration();

  			}

  			$this->validateConfiguration();
  		}
  	}
  
  	/**
  	 * @brief initializes the LDAP backend
  	 * @param $force read the config settings no matter what
  	 *
  	 * initializes the LDAP backend
  	 */
  	public function init($force = false) {
  		$this->readConfiguration($force);
  		$this->establishConnection();
  	}
  
  	/**
  	 * Returns the LDAP handler
  	 */
  	public function getConnectionResource() {
  		if(!$this->ldapConnectionRes) {
  			$this->init();

  		} else if(!$this->ldap->isResource($this->ldapConnectionRes)) {

  			$this->ldapConnectionRes = null;
  			$this->establishConnection();
  		}
  		if(is_null($this->ldapConnectionRes)) {
  			\OCP\Util::writeLog('user_ldap', 'Connection could not be established', \OCP\Util::ERROR);
  		}
  		return $this->ldapConnectionRes;
  	}
  
  	private function getCacheKey($key) {
  		$prefix = 'LDAP-'.$this->configID.'-'.$this->configPrefix.'-';
  		if(is_null($key)) {
  			return $prefix;
  		}
  		return $prefix.md5($key);
  	}
  
  	public function getFromCache($key) {
  		if(!$this->configured) {
  			$this->readConfiguration();
  		}

  		if(!$this->configuration->ldapCacheTTL) {

  			return null;
  		}
  		if(!$this->isCached($key)) {
  			return null;
  
  		}
  		$key = $this->getCacheKey($key);
  
  		return unserialize(base64_decode($this->cache->get($key)));
  	}
  
  	public function isCached($key) {
  		if(!$this->configured) {
  			$this->readConfiguration();
  		}

  		if(!$this->configuration->ldapCacheTTL) {

  			return false;
  		}
  		$key = $this->getCacheKey($key);
  		return $this->cache->hasKey($key);
  	}
  
  	public function writeToCache($key, $value) {
  		if(!$this->configured) {
  			$this->readConfiguration();
  		}

  		if(!$this->configuration->ldapCacheTTL
  			|| !$this->configuration->ldapConfigurationActive) {

  			return null;
  		}
  		$key   = $this->getCacheKey($key);
  		$value = base64_encode(serialize($value));

  		$this->cache->set($key, $value, $this->configuration->ldapCacheTTL);

  	}
  
  	public function clearCache() {
  		$this->cache->clear($this->getCacheKey(null));
  	}

  	/**

  	 * @brief Caches the general LDAP configuration.
  	 * @param $force optional. true, if the re-read should be forced. defaults
  	 * to false.
  	 * @return null

  	 */
  	private function readConfiguration($force = false) {
  		if((!$this->configured || $force) && !is_null($this->configID)) {

  			$this->configuration->readConfiguration();

  			$this->configured = $this->validateConfiguration();
  		}
  	}
  
  	/**

  	 * @brief set LDAP configuration with values delivered by an array, not read from configuration
  	 * @param $config array that holds the config parameters in an associated array
  	 * @param &$setParameters optional; array where the set fields will be given to
  	 * @return true if config validates, false otherwise. Check with $setParameters for detailed success on single parameters
  	 */
  	public function setConfiguration($config, &$setParameters = null) {

  		if(is_null($setParameters)) {
  			$setParameters = array();

  		}

  		$this->doNotValidate = false;
  		$this->configuration->setConfiguration($config, $setParameters);
  		if(count($setParameters) > 0) {
  			$this->configured = $this->validateConfiguration();

  		}

  
  		return $this->configured;
  	}
  
  	/**

  	 * @brief saves the current Configuration in the database and empties the
  	 * cache
  	 * @return null

  	 */
  	public function saveConfiguration() {

  		$this->configuration->saveConfiguration();

  		$this->clearCache();
  	}
  
  	/**
  	 * @brief get the current LDAP configuration
  	 * @return array
  	 */
  	public function getConfiguration() {
  		$this->readConfiguration();

  		$config = $this->configuration->getConfiguration();
  		$cta = $this->configuration->getConfigTranslationArray();
  		$result = array();
  		foreach($cta as $dbkey => $configkey) {
  			switch($configkey) {
  				case 'homeFolderNamingRule':
  					if(strpos($config[$configkey], 'attr:') === 0) {
  						$result[$dbkey] = substr($config[$configkey], 5);
  					} else {
  						$result[$dbkey] = '';
  					}
  					break;
  				case 'ldapBase':
  				case 'ldapBaseUsers':
  				case 'ldapBaseGroups':
  				case 'ldapAttributesForUserSearch':
  				case 'ldapAttributesForGroupSearch':
  					if(is_array($config[$configkey])) {
  						$result[$dbkey] = implode("
  ", $config[$configkey]);
  						break;
  					} //else follows default
  				default:
  					$result[$dbkey] = $config[$configkey];

  			}

  		}

  		return $result;

  	}

  	private function doSoftValidation() {
  		//if User or Group Base are not set, take over Base DN setting
  		foreach(array('ldapBaseUsers', 'ldapBaseGroups') as $keyBase) {
  		    $val = $this->configuration->$keyBase;
  			if(empty($val)) {
  				$obj = strpos('Users', $keyBase) !== false ? 'Users' : 'Groups';
  				\OCP\Util::writeLog('user_ldap',
  									'Base tree for '.$obj.
  									' is empty, using Base DN',
  									\OCP\Util::INFO);
  				$this->configuration->$keyBase = $this->configuration->ldapBase;

  			}
  		}

  
  		$groupFilter = $this->configuration->ldapGroupFilter;
  		if(empty($groupFilter)) {

  			\OCP\Util::writeLog('user_ldap',

  								'No group filter is specified, LDAP group '.
  								'feature will not be used.',
  								\OCP\Util::INFO);

  		}

  		foreach(array('ldapExpertUUIDUserAttr'  => 'ldapUuidUserAttribute',
  					  'ldapExpertUUIDGroupAttr' => 'ldapUuidGroupAttribute')
  				as $expertSetting => $effectiveSetting) {
  			$uuidOverride = $this->configuration->$expertSetting;
  			if(!empty($uuidOverride)) {
  				$this->configuration->$effectiveSetting = $uuidOverride;
  			} else {
  				$uuidAttributes = array('auto', 'entryuuid', 'nsuniqueid',
  										'objectguid', 'guid');
  				if(!in_array($this->configuration->$effectiveSetting,
  							$uuidAttributes)
  					&& (!is_null($this->configID))) {
  					$this->configuration->$effectiveSetting = 'auto';
  					$this->configuration->saveConfiguration();
  					\OCP\Util::writeLog('user_ldap',
  										'Illegal value for the '.
  										$effectiveSetting.', '.'reset to '.
  										'autodetect.', \OCP\Util::INFO);
  				}

  			}
  		}

  		$backupPort = $this->configuration->ldapBackupPort;
  		if(empty($backupPort)) {
  			$this->configuration->backupPort = $this->configuration->ldapPort;

  		}

  
  		//make sure empty search attributes are saved as simple, empty array
  		$sakeys = array('ldapAttributesForUserSearch',
  						'ldapAttributesForGroupSearch');
  		foreach($sakeys as $key) {
  			$val = $this->configuration->$key;
  			if(is_array($val) && count($val) === 1 && empty($val[0])) {
  				$this->configuration->$key = array();
  			}

  		}

  
  		if((stripos($this->configuration->ldapHost, 'ldaps://') === 0)
  			&& $this->configuration->ldapTLS) {
  			$this->configuration->ldapTLS = false;

  			\OCP\Util::writeLog('user_ldap',

  								'LDAPS (already using secure connection) and '.
  								'TLS do not work together. Switched off TLS.',
  								\OCP\Util::INFO);

  		}

  	}
  
  	private function doCriticalValidation() {
  		$configurationOK = true;
  		$errorStr = 'Configuration Error (prefix '.
  					strval($this->configPrefix).'): ';
  
  		//options that shall not be empty
  		$options = array('ldapHost', 'ldapPort', 'ldapUserDisplayName',
  						 'ldapGroupDisplayName', 'ldapLoginFilter');
  		foreach($options as $key) {
  			$val = $this->configuration->$key;
  			if(empty($val)) {
  				switch($key) {
  					case 'ldapHost':
  						$subj = 'LDAP Host';
  						break;
  					case 'ldapPort':
  						$subj = 'LDAP Port';
  						break;
  					case 'ldapUserDisplayName':
  						$subj = 'LDAP User Display Name';
  						break;
  					case 'ldapGroupDisplayName':
  						$subj = 'LDAP Group Display Name';
  						break;
  					case 'ldapLoginFilter':
  						$subj = 'LDAP Login Filter';
  						break;
  					default:
  						$subj = $key;
  						break;
  				}
  				$configurationOK = false;
  				\OCP\Util::writeLog('user_ldap',
  									$errorStr.'No '.$subj.' given!',
  									\OCP\Util::WARN);
  			}

  		}

  
  		//combinations
  		$agent = $this->configuration->ldapAgentName;
  		$pwd = $this->configuration->ldapAgentPassword;
  		if((empty($agent) && !empty($pwd)) || (!empty($agent) && empty($pwd))) {

  			\OCP\Util::writeLog('user_ldap',

  								$errorStr.'either no password is given for the'.
  								'user agent or a password is given, but not an'.
  								'LDAP agent.',

  				\OCP\Util::WARN);
  			$configurationOK = false;
  		}

  
  		$base = $this->configuration->ldapBase;
  		$baseUsers = $this->configuration->ldapBaseUsers;
  		$baseGroups = $this->configuration->ldapBaseGroups;
  
  		if(empty($base) && empty($baseUsers) && empty($baseGroups)) {

  			\OCP\Util::writeLog('user_ldap',

  								$errorStr.'Not a single Base DN given.',
  								\OCP\Util::WARN);

  			$configurationOK = false;
  		}

  
  		if(mb_strpos($this->configuration->ldapLoginFilter, '%uid', 0, 'UTF-8')
  		   === false) {

  			\OCP\Util::writeLog('user_ldap',

  								$errorStr.'login filter does not contain %uid '.
  								'place holder.',
  								\OCP\Util::WARN);

  			$configurationOK = false;
  		}

  		return $configurationOK;
  	}
  
  	/**

  	 * @brief Validates the user specified configuration
  	 * @returns true if configuration seems OK, false otherwise

  	 */

  	private function validateConfiguration() {
  
  		if($this->doNotValidate) {
  			//don't do a validation if it is a new configuration with pure
  			//default values. Will be allowed on changes via __set or
  			//setConfiguration
  			return false;
  		}
  
  		// first step: "soft" checks: settings that are not really
  		// necessary, but advisable. If left empty, give an info message
  		$this->doSoftValidation();
  
  		//second step: critical checks. If left empty or filled wrong, set as
  		//unconfigured and give a warning.
  		return $this->doCriticalValidation();

  	}

  	/**
  	 * Connects and Binds to LDAP
  	 */
  	private function establishConnection() {

  		if(!$this->configuration->ldapConfigurationActive) {

  			return null;
  		}
  		static $phpLDAPinstalled = true;
  		if(!$phpLDAPinstalled) {
  			return false;
  		}
  		if(!$this->configured) {

  			\OCP\Util::writeLog('user_ldap',
  								'Configuration is invalid, cannot connect',
  								\OCP\Util::WARN);

  			return false;
  		}
  		if(!$this->ldapConnectionRes) {

  			if(!$this->ldap->areLDAPFunctionsAvailable()) {

  				$phpLDAPinstalled = false;
  				\OCP\Util::writeLog('user_ldap',

  									'function ldap_connect is not available. Make '.
  									'sure that the PHP ldap module is installed.',
  									\OCP\Util::ERROR);

  
  				return false;
  			}

  			if($this->configuration->turnOffCertCheck) {

  				if(putenv('LDAPTLS_REQCERT=never')) {
  					\OCP\Util::writeLog('user_ldap',
  						'Turned off SSL certificate validation successfully.',
  						\OCP\Util::WARN);
  				} else {

  					\OCP\Util::writeLog('user_ldap',
  										'Could not turn off SSL certificate validation.',
  										\OCP\Util::WARN);

  				}
  			}

  			if(!$this->configuration->ldapOverrideMainServer
  			   && !$this->getFromCache('overrideMainServer')) {
  				$this->doConnect($this->configuration->ldapHost,
  								 $this->configuration->ldapPort);

  				$bindStatus = $this->bind();

  				$error = $this->ldap->isResource($this->ldapConnectionRes) ?
  							$this->ldap->errno($this->ldapConnectionRes) : -1;

  			} else {
  				$bindStatus = false;
  				$error = null;
  			}
  
  			//if LDAP server is not reachable, try the Backup (Replica!) Server
  			if((!$bindStatus && ($error !== 0))

  				|| $this->configuration->ldapOverrideMainServer

  				|| $this->getFromCache('overrideMainServer')) {

  					$this->doConnect($this->configuration->ldapBackupHost,
  									 $this->configuration->ldapBackupPort);

  					$bindStatus = $this->bind();
  					if(!$bindStatus && $error === -1) {
  						//when bind to backup server succeeded and failed to main server,
  						//skip contacting him until next cache refresh
  						$this->writeToCache('overrideMainServer', true);
  					}
  			}
  			return $bindStatus;
  		}
  	}
  
  	private function doConnect($host, $port) {
  		if(empty($host)) {
  			return false;
  		}
  		if(strpos($host, '://') !== false) {
  			//ldap_connect ignores port paramater when URLs are passed
  			$host .= ':' . $port;
  		}

  		$this->ldapConnectionRes = $this->ldap->connect($host, $port);
  		if($this->ldap->setOption($this->ldapConnectionRes, LDAP_OPT_PROTOCOL_VERSION, 3)) {
  			if($this->ldap->setOption($this->ldapConnectionRes, LDAP_OPT_REFERRALS, 0)) {
  				if($this->configuration->ldapTLS) {
  					$this->ldap->startTls($this->ldapConnectionRes);

  				}
  			}
  		}
  	}
  
  	/**
  	 * Binds to LDAP
  	 */
  	public function bind() {
  		static $getConnectionResourceAttempt = false;

  		if(!$this->configuration->ldapConfigurationActive) {

  			return false;
  		}
  		if($getConnectionResourceAttempt) {
  			$getConnectionResourceAttempt = false;
  			return false;
  		}
  		$getConnectionResourceAttempt = true;
  		$cr = $this->getConnectionResource();
  		$getConnectionResourceAttempt = false;

  		if(!$this->ldap->isResource($cr)) {

  			return false;
  		}

  		$ldapLogin = @$this->ldap->bind($cr,
  										$this->configuration->ldapAgentName,
  										$this->configuration->ldapAgentPassword);

  		if(!$ldapLogin) {
  			\OCP\Util::writeLog('user_ldap',

  				'Bind failed: ' . $this->ldap->errno($cr) . ': ' . $this->ldap->error($cr),

  				\OCP\Util::ERROR);
  			$this->ldapConnectionRes = null;
  			return false;
  		}
  		return true;
  	}
  
  }