<?php
/**
 * eGroupWare API - Authentication baseclass
 *
 * @link http://www.egroupware.org
 * @author Ralf Becker <ralfbecker@outdoor-training.de>
 * @author Miles Lott <milos@groupwhere.org>
 * @copyright 2004 by Miles Lott <milos@groupwhere.org>
 * @license http://opensource.org/licenses/lgpl-license.php LGPL - GNU Lesser General Public License
 * @package api
 * @subpackage authentication
 * @version $Id$
 */

// allow to set an application depending authentication type (eg. for syncml, groupdav, ...)
if (isset($GLOBALS['egw_info']['server']['auth_type_'.$GLOBALS['egw_info']['flags']['currentapp']]) &&
	$GLOBALS['egw_info']['server']['auth_type_'.$GLOBALS['egw_info']['flags']['currentapp']])
{
	$GLOBALS['egw_info']['server']['auth_type'] = $GLOBALS['egw_info']['server']['auth_type_'.$GLOBALS['egw_info']['flags']['currentapp']];
}
if(empty($GLOBALS['egw_info']['server']['auth_type']))
{
	$GLOBALS['egw_info']['server']['auth_type'] = 'sql';
}
//error_log('using auth_type='.$GLOBALS['egw_info']['server']['auth_type'].', currentapp='.$GLOBALS['egw_info']['flags']['currentapp']);

/**
 * eGroupWare API - Authentication baseclass, password auth and crypt functions
 *
 * Many functions based on code from Frank Thomas <frank@thomas-alfeld.de>
 * which can be seen at http://www.thomas-alfeld.de/frank/
 *
 * Other functions from class.common.inc.php originally from phpGroupWare
 */
class auth
{
	static $error;

	/**
	 * Holds instance of backend
	 *
	 * @var auth_backend
	 */
	private $backend;

	function __construct()
	{
		$backend_class = 'auth_'.$GLOBALS['egw_info']['server']['auth_type'];

		$this->backend = new $backend_class;

		if (!($this->backend instanceof auth_backend))
		{
			throw new egw_exception_assertion_failed("Auth backend class $backend_class is NO auth_backend!");
		}
	}

	/**
	 * password authentication against password stored in sql datababse
	 *
	 * @param string $username username of account to authenticate
	 * @param string $passwd corresponding password
	 * @param string $passwd_type='text' 'text' for cleartext passwords (default)
	 * @return boolean true if successful authenticated, false otherwise
	 */
	function authenticate($username, $passwd, $passwd_type='text')
	{
		return $this->backend->authenticate($username, $passwd, $passwd_type);
	}

	/**
	 * changes password in sql datababse
	 *
	 * @param string $old_passwd must be cleartext
	 * @param string $new_passwd must be cleartext
	 * @param int $account_id account id of user whose passwd should be changed
	 * @return boolean true if password successful changed, false otherwise
	 */
	function change_password($old_passwd, $new_passwd, $account_id=0)
	{
		if (($ret = $this->backend->change_password($old_passwd, $new_passwd, $account_id)) &&
			($account_id == $GLOBALS['egw_info']['user']['account_id']))
		{
			// need to change current users password in session
			egw_cache::setSession('phpgwapi', 'password', base64_encode($new_passwd));
			// invalidate EGroupware session, as password is stored in egw_info in session
			egw::invalidate_session_cache();
		}
		return $ret;
	}

	/**
	 * return a random string of letters [0-9a-zA-Z] of size $size
	 *
	 * @param $size int-size of random string to return
	 */
	static function randomstring($size)
	{
		static $random_char = array(
			'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f',
			'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
			'w','x','y','z','A','B','C','D','E','F','G','H','I','J','K','L',
			'M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'
		);

		$s = '';
		for ($i=0; $i<$size; $i++)
		{
			$s .= $random_char[mt_rand(1,61)];
		}
		return $s;
	}

	/**
	 * encrypt password
	 *
	 * uses the encryption type set in setup and calls the appropriate encryption functions
	 *
	 * @param $password password to encrypt
	 */
	static function encrypt_password($password,$sql=False)
	{
		if($sql)
		{
			return self::encrypt_sql($password);
		}
		return self::encrypt_ldap($password);
	}

	/**
	 * compares an encrypted password
	 *
	 * encryption type set in setup and calls the appropriate encryption functions
	 *
	 * @param string $cleartext cleartext password
	 * @param string $encrypted encrypted password, can have a {hash} prefix, which overrides $type
	 * @param string $type_i type of encryption
	 * @param string $username used as optional key of encryption for md5_hmac
	 * @param string &$type=null on return detected type of hash
	 * @return boolean
	 */
	static function compare_password($cleartext, $encrypted, $type_in, $username='', &$type=null)
	{
		// allow to specify the hash type to prefix the hash, to easy migrate passwords from ldap
		$type = $type_in;
		$saved_enc = $encrypted;
		if (preg_match('/^\\{([a-z_5]+)\\}(.+)$/i',$encrypted,$matches))
		{
			$type = strtolower($matches[1]);
			$encrypted = $matches[2];

			switch($type)	// some hashs are specially "packed" in ldap
			{
				case 'md5':
					$encrypted = implode('',unpack('H*',base64_decode($encrypted)));
					break;
				case 'plain':
				case 'crypt':
					// nothing to do
					break;
				default:
					$encrypted = $saved_enc;
					break;
			}
		}
		elseif($encrypted[0] == '$')
		{
			$type = 'crypt';
		}

		switch($type)
		{
			case 'plain':
				$ret = $cleartext === $encrypted;
				break;
			case 'smd5':
				$ret = self::smd5_compare($cleartext,$encrypted);
				break;
			case 'sha':
				$ret = self::sha_compare($cleartext,$encrypted);
				break;
			case 'ssha':
				$ret = self::ssha_compare($cleartext,$encrypted);
				break;
			case 'crypt':
			case 'des':
			case 'md5_crypt':
			case 'blowish_crypt':	// was for some time a typo in setup
			case 'blowfish_crypt':
			case 'ext_crypt':
			case 'sha256_crypt':
			case 'sha512_crypt':
				$ret = self::crypt_compare($cleartext, $encrypted, $type);
				break;
			case 'md5_hmac':
				$ret = self::md5_hmac_compare($cleartext,$encrypted,$username);
				break;
			default:
				$type = 'md5';
				// fall through
			case 'md5':
				$ret = md5($cleartext) === $encrypted;
				break;
		}
		//error_log(__METHOD__."('$cleartext', '$encrypted', '$type_in', '$username') type='$type' returning ".array2string($ret));
		return $ret;
	}

	/**
	 * Parameters used for crypt: const name, salt prefix, len of random salt, postfix
	 *
	 * @var array
	 */
	static $crypt_params = array(	//
		'crypt' => array('CRYPT_STD_DES', '', 2, ''),
		'ext_crypt' => array('CRYPT_EXT_DES', '_J9..', 4, ''),
		'md5_crypt' => array('CRYPT_MD5', '$1$', 8, '$'),
		//'old_blowfish_crypt' => array('CRYPT_BLOWFISH', '$2$', 13, ''),	// old blowfish hash not in line with php.net docu, but could be in use
		'blowfish_crypt' => array('CRYPT_BLOWFISH', '$2a$12$', 22, ''),	// $2a$12$ = 2^12 = 4096 rounds
		'sha256_crypt' => array('CRYPT_SHA256', '$5$', 16, '$'),	// no "round=N$" --> default of 5000 rounds
		'sha512_crypt' => array('CRYPT_SHA512', '$6$', 16, '$'),	// no "round=N$" --> default of 5000 rounds
	);

	/**
	 * compare crypted passwords for authentication whether des,ext_des,md5, or blowfish crypt
	 *
	 * @param string $form_val user input value for comparison
	 * @param string $db_val   stored value / hash (from database)
	 * @param string &$type    detected crypt type on return
	 * @return boolean	 True on successful comparison
	*/
	static function crypt_compare($form_val, $db_val, &$type)
	{
		// detect type of hash by salt part of $db_val
		list($first, $dollar, $salt, $salt2) = explode('$', $db_val);
		foreach(self::$crypt_params as $type => $params)
		{
			list(,$prefix, $random, $postfix) = $params;
			list(,$d) = explode('$', $prefix);
			if ($dollar === $d || !$dollar && ($first[0] === $prefix[0] || $first[0] !== '_' && !$prefix))
			{
				$len = !$postfix ? strlen($prefix)+$random : strlen($prefix.$salt.$postfix);
				// sha(256|512) might contain options, explicit $rounds=N$ prefix in salt
				if (($type == 'sha256_crypt' || $type == 'sha512_crypt') && substr($salt, 0, 7) === 'rounds=')
				{
					$len += strlen($salt2)+1;
				}
				break;
			}
		}

		$salt = substr($db_val, 0, $len);
		$new_hash = crypt($form_val, $salt);
		//error_log(__METHOD__."('$form_val', '$db_val') type=$type --> len=$len --> salt='$salt' --> new_hash='$new_hash' returning ".array2string($db_val === $new_hash));

		return $db_val === $new_hash;
	}

	/**
	 * encrypt password for ldap
	 *
	 * uses the encryption type set in setup and calls the appropriate encryption functions
	 *
	 * @param $password password to encrypt
	 * @param $type=null default to $GLOBALS['egw_info']['server']['ldap_encryption_type']
	 * @return string
	 */
	static function encrypt_ldap($password, $type=null)
	{
		if (is_null($type)) $type = $GLOBALS['egw_info']['server']['ldap_encryption_type'];

		$salt = '';
		switch(strtolower($type))
		{
			default:	// eg. setup >> config never saved
			case 'des':
			case 'blowish_crypt':	// was for some time a typo in setup
				$type = $type == 'blowish_crypt' ? 'blowfish_crypt' : 'crypt';
				// fall through
			case 'crypt':
			case 'sha256_crypt':
			case 'sha512_crypt':
			case 'blowfish_crypt':
			case 'md5_crypt':
			case 'ext_crypt':
				list($const, $prefix, $len, $postfix) = self::$crypt_params[$type];
				if(defined($const) && constant($const) == 1)
				{
					$salt = $prefix.self::randomstring($len).$postfix;
					$e_password = '{crypt}'.crypt($password, $salt);
					break;
				}
				self::$error = 'no '.str_replace('_', ' ', $type);
				$e_password = false;
				break;
			case 'md5':
				/* New method taken from the openldap-software list as recommended by
				 * Kervin L. Pierre" <kervin@blueprint-tech.com>
				 */
				$e_password = '{md5}' . base64_encode(pack("H*",md5($password)));
				break;
			case 'smd5':
				$salt = self::randomstring(16);
				$hash = md5($password . $salt, true);
				$e_password = '{SMD5}' . base64_encode($hash . $salt);
				break;
			case 'sha':
				$e_password = '{SHA}' . base64_encode(sha1($password,true));
				break;
			case 'ssha':
				$salt = self::randomstring(16);
				$hash = sha1($password . $salt, true);
				$e_password = '{SSHA}' . base64_encode($hash . $salt);
				break;
			case 'plain':
				// if plain no type is prepended
				$e_password = $password;
				break;
		}
		//error_log(__METHOD__."('$password', ".array2string($type).") returning ".array2string($e_password).(self::$error ? ' error='.self::$error : ''));
		return $e_password;
	}

	/**
	 * Create a password for storage in the accounts table
	 *
	 * @param string $password
	 * @param string $type=null default $GLOBALS['egw_info']['server']['sql_encryption_type']
	 * @return string hash
	 */
	static function encrypt_sql($password, $type=null)
	{
		/* Grab configured type, or default to md5() (old method) */
		if (is_null($type))
		{
			$type = @$GLOBALS['egw_info']['server']['sql_encryption_type'] ?
				strtolower($GLOBALS['egw_info']['server']['sql_encryption_type']) : 'md5';
		}
		switch($type)
		{
			case 'plain':
				// since md5 is the default, type plain must be prepended, for eGroupware to understand
				$e_password = '{PLAIN}'.$password;
				break;

			case 'md5':
				/* This is the old standard for password storage in SQL */
				$e_password = md5($password);
				break;

			// all other types are identical to ldap, so no need to doublicate the code here
			case 'des':
			case 'blowish_crypt':	// was for some time a typo in setup
			case 'crypt':
			case 'sha256_crypt':
			case 'sha512_crypt':
			case 'blowfish_crypt':
			case 'md5_crypt':
			case 'ext_crypt':
			case 'smd5':
			case 'sha':
			case 'ssha':
				$e_password = self::encrypt_ldap($password, $type);
				break;

			default:
				self::$error = 'no valid encryption available';
				$e_password = false;
				break;
		}
		//error_log(__METHOD__."('$password') using '$type' returning ".array2string($e_password).(self::$error ? ' error='.self::$error : ''));
		return $e_password;
	}

	/**
	 * Get available password hashes sorted by securest first
	 *
	 * @param string &$securest=null on return securest available hash
	 * @return array hash => label
	 */
	public static function passwdhashes(&$securest=null)
	{
		$hashes = array();

		/* Check for available crypt methods based on what is defined by php */
		if(defined('CRYPT_BLOWFISH') && CRYPT_BLOWFISH == 1)
		{
			$hashes['blowfish_crypt'] = 'blowfish_crypt';
		}
		if(defined('CRYPT_SHA512') && CRYPT_SHA512 == 1)
		{
			$hashes['sha512_crypt'] = 'sha512_crypt';
		}
		if(defined('CRYPT_SHA256') && CRYPT_SHA256 == 1)
		{
			$hashes['sha256_crypt'] = 'sha256_crypt';
		}
		if(defined('CRYPT_MD5') && CRYPT_MD5 == 1)
		{
			$hashes['md5_crypt'] = 'md5_crypt';
		}
		if(defined('CRYPT_EXT_DES') && CRYPT_EXT_DES == 1)
		{
			$hashes['ext_crypt'] = 'ext_crypt';
		}
		$hashes += array(
			'ssha' => 'ssha',
			'smd5' => 'smd5',
			'sha'  => 'sha',
		);
		if(@defined('CRYPT_STD_DES') && CRYPT_STD_DES == 1)
		{
			$hashes['crypt'] = 'crypt';
		}

		$hashes += array(
			'md5' => 'md5',
			'plain' => 'plain',
		);

		// mark the securest algorithm for the user
		list($securest) = each($hashes); reset($hashes);
		$hashes[$securest] .= ' ('.lang('securest').')';

		return $hashes;
	}

	/**
	 * Checks if a given password is "safe"
	 *
	 * @param string $login
	 * @abstract atm a simple check in length, #digits, #uppercase and #lowercase
	 * 				could be made more safe using e.g. pecl library cracklib
	 * 				but as pecl dosn't run on any platform and isn't GPL'd
	 * 				i haven't implemented it yet
	 *				Windows compatible check is: 7 char lenth, 1 Up, 1 Low, 1 Num and 1 Special
	 * @author cornelius weiss <egw at von-und-zu-weiss.de>
	 * @return mixed false if password is considered "safe" or a string $message if "unsafe"
	 */
	static function crackcheck($passwd)
	{
		if (!preg_match('/.{'. ($noc=7). ',}/',$passwd))
		{
			$message = lang('Password must have at least %1 characters',$noc). '<br>';
		}
		if(!preg_match('/(.*\d.*){'. ($non=1). ',}/',$passwd))
		{
			$message .= lang('Password must contain at least %1 numbers',$non). '<br>';
		}
		if(!preg_match('/(.*[[:upper:]].*){'. ($nou=1). ',}/',$passwd))
		{
			$message .= lang('Password must contain at least %1 uppercase letters',$nou). '<br>';
		}
		if(!preg_match('/(.*[[:lower:]].*){'. ($nol=1). ',}/',$passwd))
		{
			$message .= lang('Password must contain at least %1 lowercase letters',$nol). '<br>';
		}
		if(!preg_match('/(.*[\\!"#$%&\'()*+,-.\/:;<=>?@\[\]\^_ {|}~`].*){'. ($nol=1). ',}/',$passwd))
		{
			$message .= lang('Password must contain at least %1 special characters',$nol). '<br>';
		}
		return $message ? $message : false;
	}

	/**
	 * compare SMD5-encrypted passwords for authentication
	 *
	 * @param string $form_val user input value for comparison
	 * @param string $db_val stored value (from database)
	 * @return boolean True on successful comparison
	*/
	static function smd5_compare($form_val,$db_val)
	{
		/* Start with the first char after {SMD5} */
		$hash = base64_decode(substr($db_val,6));

		/* SMD5 hashes are 16 bytes long */
		$orig_hash = cut_bytes($hash, 0, 16);	// binary string need to use cut_bytes, not mb_substr(,,'utf-8')!
		$salt = cut_bytes($hash, 16);

		$new_hash = md5($form_val . $salt,true);
		//echo '<br>  DB: ' . base64_encode($orig_hash) . '<br>FORM: ' . base64_encode($new_hash);

		return strcmp($orig_hash,$new_hash) == 0;
	}

	/**
	 * compare SHA-encrypted passwords for authentication
	 *
	 * @param string $form_val user input value for comparison
	 * @param string $db_val   stored value (from database)
	 * @return boolean True on successful comparison
	*/
	static function sha_compare($form_val,$db_val)
	{
		/* Start with the first char after {SHA} */
		$hash = base64_decode(substr($db_val,5));
		$new_hash = sha1($form_val,true);
		//echo '<br>  DB: ' . base64_encode($orig_hash) . '<br>FORM: ' . base64_encode($new_hash);

		return strcmp($hash,$new_hash) == 0;
	}

	/**
	 * compare SSHA-encrypted passwords for authentication
	 *
	 * @param string $form_val user input value for comparison
	 * @param string $db_val   stored value (from database)
	 * @return boolean	 True on successful comparison
	*/
	static function ssha_compare($form_val,$db_val)
	{
		/* Start with the first char after {SSHA} */
		$hash = base64_decode(substr($db_val, 6));

		// SHA-1 hashes are 160 bits long
		$orig_hash = cut_bytes($hash, 0, 20);	// binary string need to use cut_bytes, not mb_substr(,,'utf-8')!
		$salt = cut_bytes($hash, 20);
		$new_hash = sha1($form_val . $salt,true);

		//error_log(__METHOD__."('$form_val', '$db_val') hash='$hash', orig_hash='$orig_hash', salt='$salt', new_hash='$new_hash' returning ".array2string(strcmp($orig_hash,$new_hash) == 0));
		return strcmp($orig_hash,$new_hash) == 0;
	}

	/**
	 * compare md5_hmac-encrypted passwords for authentication (see RFC2104)
	 *
	 * @param string $form_val user input value for comparison
	 * @param string $db_val   stored value (from database)
	 * @param string $key       key for md5_hmac-encryption (username for imported smf users)
	 * @return boolean	 True on successful comparison
	 */
	static function md5_hmac_compare($form_val,$db_val,$key)
	{
		$key = str_pad(strlen($key) <= 64 ? $key : pack('H*', md5($key)), 64, chr(0x00));
		$md5_hmac = md5(($key ^ str_repeat(chr(0x5c), 64)) . pack('H*', md5(($key ^ str_repeat(chr(0x36), 64)). $form_val)));

		return strcmp($md5_hmac,$db_val) == 0;
	}
}

/**
 * Interface for authentication backend
 */
interface auth_backend
{
	/**
	 * password authentication against password stored in sql datababse
	 *
	 * @param string $username username of account to authenticate
	 * @param string $passwd corresponding password
	 * @param string $passwd_type='text' 'text' for cleartext passwords (default)
	 * @return boolean true if successful authenticated, false otherwise
	 */
	function authenticate($username, $passwd, $passwd_type='text');

	/**
	 * changes password in sql datababse
	 *
	 * @param string $old_passwd must be cleartext
	 * @param string $new_passwd must be cleartext
	 * @param int $account_id account id of user whose passwd should be changed
	 * @return boolean true if password successful changed, false otherwise
	 */
	function change_password($old_passwd, $new_passwd, $account_id=0);
}