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<?php
/**
* Authentication module which acts as an A-Select client
*
* @author Wessel Dankers, Tilburg University
*/
class sspmod_aselect_Auth_Source_aselect extends SimpleSAML_Auth_Source {
private $app_id = 'simplesamlphp';
private $server_id;
private $server_url;
private $private_key;
/**
* Constructor for this authentication source.
*
* @param array $info Information about this authentication source.
* @param array $config Configuration.
*/
public function __construct($info, $config) {
/* Call the parent constructor first, as required by the interface. */
parent::__construct($info, $config);
$cfg = SimpleSAML_Configuration::loadFromArray($config,
'Authentication source ' . var_export($this->authId, true));
$cfg->getValueValidate('type', array('app'), 'app');
$this->app_id = $cfg->getString('app_id');
$this->private_key = $cfg->getString('private_key', null);
// accept these arguments with '_' for consistency
// accept these arguments without '_' for backwards compatibility
$this->server_id = $cfg->getString('serverid', null);
if($this->server_id === null)
$this->server_id = $cfg->getString('server_id');
$this->server_url = $cfg->getString('serverurl', null);
if($this->server_url === null)
$this->server_url = $cfg->getString('server_url');
}
/**
* Initiate authentication.
*
* @param array &$state Information about the current authentication.
*/
public function authenticate(&$state) {
$state['aselect::authid'] = $this->authId;
$id = SimpleSAML_Auth_State::saveState($state, 'aselect:login', true);
try {
$app_url = SimpleSAML_Module::getModuleURL('aselect/credentials.php', array('ssp_state' => $id));
$as_url = $this->request_authentication($app_url);
SimpleSAML_Utilities::redirectTrustedURL($as_url);
} catch(Exception $e) {
// attach the exception to the state
SimpleSAML_Auth_State::throwException($state, $e);
}
}
/**
* Sign a string using the configured private key
*
* @param string $str The string to calculate a signature for
*/
private function base64_signature($str) {
$key = openssl_pkey_get_private($this->private_key);
if($key === false)
throw new SimpleSAML_Error_Exception("Unable to load private key: ".openssl_error_string());
if(!openssl_sign($str, $sig, $key))
throw new SimpleSAML_Error_Exception("Unable to create signature: ".openssl_error_string());
openssl_pkey_free($key);
return base64_encode($sig);
}
/**
* Parse a base64 encoded attribute blob. Can't use parse_str() because it
* may contain multi-valued attributes.
*
* @param string $base64 The base64 string to decode.
*/
private static function decode_attributes($base64) {
$blob = base64_decode($base64, true);
if($blob === false)
throw new SimpleSAML_Error_Exception("Attributes parameter base64 malformed");
$pairs = explode('&', $blob);
$ret = array();
foreach($pairs as $pair) {
$keyval = explode('=', $pair, 2);
if(count($keyval) < 2)
throw new SimpleSAML_Error_Exception("Missing value in attributes parameter");
$key = urldecode($keyval[0]);
$val = urldecode($keyval[1]);
$ret[$key][] = $val;
}
return $ret;
}
/**
* Default options for curl invocations.
*/
private static $curl_options = array(
CURLOPT_BINARYTRANSFER => true,
CURLOPT_FAILONERROR => true,
CURLOPT_RETURNTRANSFER => true,
CURLOPT_CONNECTTIMEOUT => 1,
CURLOPT_TIMEOUT => 5,
CURLOPT_USERAGENT => "simpleSAMLphp",
);
/**
* Create a (possibly signed) URL to contact the A-Select server.
*
* @param string $request The name of the request (authenticate / verify_credentials).
* @param array $parameters The parameters to pass for this request.
*/
private function create_aselect_url($request, $parameters) {
$parameters['request'] = $request;
$parameters['a-select-server'] = $this->server_id;
if(!is_null($this->private_key)) {
$signable = '';
foreach(array('a-select-server', 'app_id', 'app_url', 'aselect_credentials', 'rid') as $p)
if(array_key_exists($p, $parameters))
$signable .= $parameters[$p];
$parameters['signature'] = $this->base64_signature($signable);
}
return SimpleSAML_Utilities::addURLparameter($this->server_url, $parameters);
}
/**
* Contact the A-Select server and return the result as an associative array.
*
* @param string $request The name of the request (authenticate / verify_credentials).
* @param array $parameters The parameters to pass for this request.
*/
private function call_aselect($request, $parameters) {
$url = $this->create_aselect_url($request, $parameters);
$curl = curl_init($url);
if($curl === false)
throw new SimpleSAML_Error_Exception("Unable to create CURL handle");
if(!curl_setopt_array($curl, self::$curl_options))
throw new SimpleSAML_Error_Exception("Unable to set CURL options: ".curl_error($curl));
$str = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if($str === false)
throw new SimpleSAML_Error_Exception("Unable to retrieve URL: $err");
parse_str($str, $res);
// message is only available with some A-Select server implementations
if($res['result_code'] != '0000')
if(array_key_exists('message', $res))
throw new SimpleSAML_Error_Exception("Unable to contact SSO service: result_code=".$res['result_code']." message=".$res['message']);
else
throw new SimpleSAML_Error_Exception("Unable to contact SSO service: result_code=".$res['result_code']);
unset($res['result_code']);
return $res;
}
/**
* Initiate authentication. Returns a URL to redirect the user to.
*
* @param string $app_url The SSP URL to return to after authenticating (similar to an ACS).
*/
public function request_authentication($app_url) {
$res = $this->call_aselect('authenticate',
array('app_id' => $this->app_id, 'app_url' => $app_url));
$as_url = $res['as_url'];
unset($res['as_url']);
return SimpleSAML_Utilities::addURLparameter($as_url, $res);
}
/**
* Verify the credentials upon return from the A-Select server. Returns an associative array
* with the information given by the A-Select server. Any attributes are pre-parsed.
*
* @param string $server_id The A-Select server ID as passed by the client
* @param string $credentials The credentials as passed by the client
* @param string $rid The request ID as passed by the client
*/
public function verify_credentials($server_id, $credentials, $rid) {
if($server_id != $this->server_id)
throw new SimpleSAML_Error_Exception("Acquired server ID ($server_id) does not match configured server ID ($this->server_id)");
$res = $this->call_aselect('verify_credentials',
array('aselect_credentials' => $credentials, 'rid' => $rid));
if(array_key_exists('attributes', $res))
$res['attributes'] = self::decode_attributes($res['attributes']);
return $res;
}
}
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