* @copyright (c) 2010 by Ralf Becker * @version $Id$ */ /** * Class to authenticate via basic or digest auth * * The more secure digest auth requires: * a) cleartext passwords in SQL table * b) md5 hashes of username, realm, password stored somewhere (NOT yet implemented) * Otherwise digest auth is not possible and therefore not offered to the client. * * Usage example: * * $GLOBALS['egw_info']['flags'] = array( * 'noheader' => True, * 'currentapp' => 'someapp', * 'no_exception_handler' => 'basic_auth', // we use a basic auth exception handler (sends exception message as basic auth realm) * 'autocreate_session_callback' => array('egw_digest_auth','autocreate_session_callback'), * 'auth_realm' => 'EGroupware', * ); * include(dirname(__FILE__).'/header.inc.php'); * * @link http://www.php.net/manual/en/features.http-auth.php * @ToDo check if we have to check if returned nonce matches our challange (not done in above link, but why would it be there) * @link http://en.wikipedia.org/wiki/Digest_access_authentication * @link http://tools.ietf.org/html/rfc2617 */ class egw_digest_auth { /** * Log to error_log: * 0 = dont * 1 = no cleartext passwords * 2 = all */ const ERROR_LOG = 1; /** * Callback to be used to create session via header include authenticated via basic or digest auth * * @param array $account NOT used! * @return string valid session-id or does NOT return at all! */ static public function autocreate_session_callback(&$account) { if (self::ERROR_LOG) error_log(__METHOD__.'() PHP_AUTH_USER='.array2string($_SERVER['PHP_AUTH_USER']).', PHP_AUTH_PW='.array2string($_SERVER['PHP_AUTH_PW']).', PHP_AUTH_DIGEST='.array2string($_SERVER['PHP_AUTH_DIGEST'])); $realm = $GLOBALS['egw_info']['flags']['auth_realm']; if (empty($realm)) $realm = 'EGroupware'; if (!isset($_SERVER['PHP_AUTH_USER']) && !isset($_SERVER['PHP_AUTH_DIGEST']) || isset($_SERVER['PHP_AUTH_DIGEST']) && (!self::is_valid($realm,$_SERVER['PHP_AUTH_DIGEST'],$username,$password) || !($sessionid = $GLOBALS['egw']->session->create($username,$password,'text'))) || isset($_SERVER['PHP_AUTH_USER']) && !($sessionid = $GLOBALS['egw']->session->create($_SERVER['PHP_AUTH_USER'],$_SERVER['PHP_AUTH_PW'],'text'))) { // if the session class gives a reason why the login failed --> append it to the REALM if ($GLOBALS['egw']->session->reason) $realm .= ': '.$GLOBALS['egw']->session->reason; header('WWW-Authenticate: Basic realm="'.$realm.'"'); self::digest_header($realm); header('HTTP/1.1 401 Unauthorized'); header('X-WebDAV-Status: 401 Unauthorized', true); echo "\n\n\n\nAuthorization failed.\n\n\n"; exit; } return $sessionid; } /** * Check if digest auth is available for a given realm (and user): do we use cleartext passwords * * If no user is given, check is NOT authoretive, as we can only check if cleartext passwords are generally used * * @param string $realm * @param string $username=null username or null to only check if we auth agains sql and use plaintext passwords * @param string &$user_pw=null stored cleartext password, if $username given AND function returns true * @return boolean true if digest auth is available, false otherwise */ static public function digest_auth_available($realm,$username=null,&$user_pw=null) { // we currently require plaintext passwords! if (!($GLOBALS['egw_info']['server']['auth_type'] == 'sql' && $GLOBALS['egw_info']['server']['sql_encryption_type'] == 'plain') || $GLOBALS['egw_info']['server']['auth_type'] == 'ldap' && $GLOBALS['egw_info']['server']['ldap_encryption_type'] == 'plain') { if (self::ERROR_LOG) error_log(__METHOD__."('$username') return false (no plaintext passwords used)"); return false; // no plain-text passwords used } // check for specific user, if given if (!is_null($username) && !(($user_pw = $GLOBALS['egw']->accounts->id2name($username,'account_pwd','u')) || $GLOBALS['egw_info']['server']['auth_type'] == 'sql' && substr($user_pw,0,7) != '{PLAIN}')) { unset($user_pw); if (self::ERROR_LOG) error_log(__METHOD__."('$realm','$username') return false (unknown user or NO plaintext password for user)"); return false; // user does NOT exist, or has no plaintext passwords (ldap server requires real root_dn or special ACL!) } if (substr($user_pw,0,7) == '{PLAIN}') $user_pw = substr($user_pw,7); if (self::ERROR_LOG) error_log(__METHOD__."('$realm','$username','$user_pw') return true"); return true; } /** * Send header offering digest auth, if it's generally available * * @param string $realm * @param string &$nonce=null on return */ static public function digest_header($realm,&$nonce=null) { if (self::digest_auth_available($realm)) { $nonce = uniqid(); header('WWW-Authenticate: Digest realm="'.$realm.'",qop="auth",nonce="'.$nonce.'",opaque="'.md5($realm).'"'); if (self::ERROR_LOG) error_log(__METHOD__."() offering digest auth for realm '$realm' using nonce='$nonce'"); } } /** * Check digest * * @param string $realm * @param string $auth_digest=null default to $_SERVER['PHP_AUTH_DIGEST'] * @param string &$username on return username * @param string &$password on return cleartext password * @return boolean true if digest is correct, false otherwise */ static public function is_valid($realm,$auth_digest=null,&$username=null,&$password=null) { if (is_null($auth_digest)) $auth_digest = $_SERVER['PHP_AUTH_DIGEST']; $data = self::parse_digest($auth_digest); if (!$data || !($A1 = self::get_digest_A1($realm,$username=$data['username'],$password=null))) { error_log(__METHOD__."('$realm','$auth_digest','$username') returning FALSE"); return false; } $A2 = md5($_SERVER['REQUEST_METHOD'].':'.$data['uri']); $valid_response = md5($A1.':'.$data['nonce'].':'.$data['nc'].':'.$data['cnonce'].':'.$data['qop'].':'.$A2); if (self::ERROR_LOG) error_log(__METHOD__."('$realm','$auth_digest','$username') response='$data[response]', valid_response='$valid_response' returning ".array2string($data['response'] === $valid_response)); return $data['response'] === $valid_response; } /** * Calculate the A1 digest hash * * @param string $realm * @param string $username * @param string &$password=null password to use or if null, on return stored password * @return string|boolean false if $password not given and can NOT be read */ static private function get_digest_A1($realm,$username,&$password=null) { if (empty($username) || empty($realm) || !self::digest_auth_available($realm,$username,$user_pw)) { return false; } if (is_null($password)) $password = $user_pw; $A1 = md5($username . ':' . $realm . ':' . $password); if (self::ERROR_LOG > 1) error_log(__METHOD__."('$realm','$username','$password') returning ".array2string($A1)); return $A1; } /** * Parse the http auth header */ static public function parse_digest($txt) { // protect against missing data $needed_parts = array('nonce'=>1, 'nc'=>1, 'cnonce'=>1, 'qop'=>1, 'username'=>1, 'uri'=>1, 'response'=>1); $data = array(); $keys = implode('|', array_keys($needed_parts)); preg_match_all('@(' . $keys . ')=(?:([\'"])([^\2]+?)\2|([^\s,]+))@', $txt, $matches, PREG_SET_ORDER); foreach ($matches as $m) { $data[$m[1]] = $m[3] ? $m[3] : $m[4]; unset($needed_parts[$m[1]]); } //error_log(__METHOD__."('$txt') returning ".array2string($needed_parts ? false : $data)); return $needed_parts ? false : $data; } }