<?php
/**
* Using this class, you can easily set up an OpenID Provider.
* It's independent of LightOpenID class.
* It requires either GMP or BCMath for session encryption,
* but will work without them (although either via SSL, or in stateless mode only).
* Also, it requires PHP >= 5.1.2
*
* This is an alpha version, using it in production code is not recommended,
* until you are *sure* that it works and is secure.
*
* Please send me messages about your testing results
* (even if successful, so I know that it has been tested).
* Also, if you think there's a way to make it easier to use, tell me -- it's an alpha for a reason.
* Same thing applies to bugs in code, suggestions,
* and everything else you'd like to say about the library.
*
* There's no usage documentation here, see the examples.
*
* @author Mewp
* @copyright Copyright (c) 2010, Mewp
* @license http://www.opensource.org/licenses/mit-license.php MIT
*/
//ini_set('error_log','log');
abstract class LightOpenIDProvider
{
# URL-s to XRDS and server location.
public $xrdsLocation, $serverLocation;
# Should we operate in server, or signon mode?
public $select_id = false;
# Lifetime of an association.
protected $assoc_lifetime = 600;
# Variables below are either set automatically, or are constant.
# -----
# Can we support DH?
protected $dh = true;
protected $ns = 'http://specs.openid.net/auth/2.0';
protected $data, $assoc;
# Default DH parameters as defined in the specification.
protected $default_modulus;
protected $default_gen = 'Ag==';
# AX <-> SREG transform
protected $ax_to_sreg = array(
'namePerson/friendly' => 'nickname',
'contact/email' => 'email',
'namePerson' => 'fullname',
'birthDate' => 'dob',
'person/gender' => 'gender',
'contact/postalCode/home' => 'postcode',
'contact/country/home' => 'country',
'pref/language' => 'language',
'pref/timezone' => 'timezone',
);
# Math
private $add, $mul, $pow, $mod, $div, $powmod;
# -----
# ------------------------------------------------------------------------ #
# Functions you probably want to implement when extending the class.
/**
* Checks whether an user is authenticated.
* The function should determine what fields it wants to send to the RP,
* and put them in the $attributes array.
* @param Array $attributes
* @param String $realm Realm used for authentication.
* @return String OP-local identifier of an authenticated user, or an empty value.
*/
abstract function checkid($realm, &$attributes);
/**
* Displays an user interface for inputting user's login and password.
* Attributes are always AX field namespaces, with stripped host part.
* For example, the $attributes array may be:
* array( 'required' => array('namePerson/friendly', 'contact/email'),
* 'optional' => array('pref/timezone', 'pref/language')
* @param String $identity Discovered identity string. May be used to extract login, unless using $this->select_id
* @param String $realm Realm used for authentication.
* @param String Association handle. must be sent as openid.assoc_handle in $_GET or $_POST in subsequent requests.
* @param Array User attributes requested by the RP.
*/
abstract function setup($identity, $realm, $assoc_handle, $attributes);
/**
* Stores an association.
* If you want to use php sessions in your provider code, you have to replace it.
* @param String $handle Association handle -- should be used as a key.
* @param Array $assoc Association data.
*/
protected function setAssoc($handle, $assoc)
{
$oldSession = session_id();
session_commit();
session_id($assoc['handle']);
session_start();
$_SESSION['assoc'] = $assoc;
session_commit();
if($oldSession) {
session_id($oldSession);
session_start();
}
}
/**
* Retreives association data.
* If you want to use php sessions in your provider code, you have to replace it.
* @param String $handle Association handle.
* @return Array Association data.
*/
protected function getAssoc($handle)
{
$oldSession = session_id();
session_commit();
session_id($handle);
session_start();
if(empty($_SESSION['assoc'])) {
return null;
}
return $_SESSION['assoc'];
session_commit();
if($oldSession) {
session_id($oldSession);
session_start();
}
}
/**
* Deletes an association.
* If you want to use php sessions in your provider code, you have to replace it.
* @param String $handle Association handle.
*/
protected function delAssoc($handle)
{
$oldSession = session_id();
session_commit();
session_id($handle);
session_start();
session_destroy();
if($oldSession) {
session_id($oldSession);
session_start();
}
}
# ------------------------------------------------------------------------ #
# Functions that you might want to implement.
/**
* Redirects the user to an url.
* @param String $location The url that the user will be redirected to.
*/
protected function redirect($location)
{
header('Location: ' . $location);
die();
}
/**
* Generates a new association handle.
* @return string
*/
protected function assoc_handle()
{
return sha1(microtime());
}
/**
* Generates a random shared secret.
* @return string
*/
protected function shared_secret($hash)
{
$length = 20;
if($hash == 'sha256') {
$length = 256;
}
$secret = '';
for($i = 0; $i < $length; $i++) {
$secret .= mt_rand(0,255);
}
return $secret;
}
/**
* Generates a private key.
* @param int $length Length of the key.
*/
protected function keygen($length)
{
$key = '';
for($i = 1; $i < $length; $i++) {
$key .= mt_rand(0,9);
}
$key .= mt_rand(1,9);
return $key;
}
# ------------------------------------------------------------------------ #
# Functions that you probably shouldn't touch.
function __construct()
{
$this->default_modulus =
'ANz5OguIOXLsDhmYmsWizjEOHTdxfo2Vcbt2I3MYZuYe91ouJ4mLBX+YkcLiemOcPy'
. 'm2CBRYHNOyyjmG0mg3BVd9RcLn5S3IHHoXGHblzqdLFEi/368Ygo79JRnxTkXjgmY0'
. 'rxlJ5bU1zIKaSDuKdiI+XUkKJX8Fvf8W8vsixYOr';
$location = (!empty($_SERVER['HTTPS']) ? 'https' : 'http') . '://'
. $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
$location = preg_replace('/\?.*/','',$location);
$this->serverLocation = $location;
$location .= (strpos($location, '?') ? '&' : '?') . 'xrds';
$this->xrdsLocation = $location;
$this->data = $_GET + $_POST;
# We choose GMP if avaiable, and bcmath otherwise
if(function_exists('gmp_add')) {
$this->add = 'gmp_add';
$this->mul = 'gmp_mul';
$this->pow = 'gmp_pow';
$this->mod = 'gmp_mod';
$this->div = 'gmp_div';
$this->powmod = 'gmp_powm';
} elseif(function_exists('bcadd')) {
$this->add = 'bcadd';
$this->mul = 'bcmul';
$this->pow = 'bcpow';
$this->mod = 'bcmod';
$this->div = 'bcdiv';
$this->powmod = 'bcpowmod';
} else {
# If neither are avaiable, we can't use DH
$this->dh = false;
}
# However, we do require the hash functions.
# They should be built-in anyway.
if(!function_exists('hash_algos')) {
$this->dh = false;
}
}
/**
* Displays an XRDS document, or redirects to it.
* By default, it detects whether it should display or redirect automatically.
* @param bool|null $force When true, always display the document, when false always redirect.
*/
function xrds($force=null)
{
if($force) {
echo $this->xrdsContent();
die();
} elseif($force === false) {
header('X-XRDS-Location: '. $this->xrdsLocation);
return;
}
if (isset($_GET['xrds'])
|| (isset($_SERVER['HTTP_ACCEPT']) && strpos($_SERVER['HTTP_ACCEPT'], 'application/xrds+xml') !== false)
) {
header('Content-Type: application/xrds+xml');
echo $this->xrdsContent();
die();
}
header('X-XRDS-Location: ' . $this->xrdsLocation);
}
/**
* Returns the content of the XRDS document
* @return String The XRDS document.
*/
protected function xrdsContent()
{
$lines = array(
'<?xml version="1.0" encoding="UTF-8"?>',
'<xrds:XRDS xmlns:xrds="xri://$xrds" xmlns="xri://$xrd*($v*2.0)">',
'<XRD>',
' <Service>',
' <Type>' . $this->ns . '/' . ($this->select_id ? 'server' : 'signon') .'</Type>',
' <URI>' . $this->serverLocation . '</URI>',
' </Service>',
'</XRD>',
'</xrds:XRDS>'
);
return implode("\n", $lines);
}
/**
* Does everything that a provider has to -- in one function.
*/
function server()
{
if(isset($this->data['openid_assoc_handle'])) {
$this->assoc = $this->getAssoc($this->data['openid_assoc_handle']);
if(isset($this->assoc['data'])) {
# We have additional data stored for setup.
$this->data += $this->assoc['data'];
unset($this->assoc['data']);
}
}
if (isset($this->data['openid_ns'])
&& $this->data['openid_ns'] == $this->ns
) {
if(!isset($this->data['openid_mode'])) $this->errorResponse();
switch($this->data['openid_mode'])
{
case 'checkid_immediate':
case 'checkid_setup':
$this->checkRealm();
# We support AX xor SREG.
$attributes = $this->ax();
if(!$attributes) {
$attributes = $this->sreg();
}
# Even if some user is authenticated, we need to know if it's
# the same one that want's to authenticate.
# Of course, if we use select_id, we accept any user.
if (($identity = $this->checkid($this->data['openid_realm'], $attrValues))
&& ($this->select_id || $identity == $this->data['openid_identity'])
) {
$this->positiveResponse($identity, $attrValues);
} elseif($this->data['openid_mode'] == 'checkid_immediate') {
$this->redirect($this->response(array('openid.mode' => 'setup_needed')));
} else {
if(!$this->assoc) {
$this->generateAssociation();
$this->assoc['private'] = true;
}
$this->assoc['data'] = $this->data;
$this->setAssoc($this->assoc['handle'], $this->assoc);
$this->setup($this->data['openid_identity'],
$this->data['openid_realm'],
$this->assoc['handle'],
$attributes);
}
break;
case 'associate':
$this->associate();
break;
case 'check_authentication':
$this->checkRealm();
if($this->verify()) {
echo "ns:$this->ns\nis_valid:true";
if(strpos($this->data['openid_signed'],'invalidate_handle') !== false) {
echo "\ninvalidate_handle:" . $this->data['openid_invalidate_handle'];
}
} else {
echo "ns:$this->ns\nis_valid:false";
}
die();
break;
default:
$this->errorResponse();
}
} else {
$this->xrds();
}
}
protected function checkRealm()
{
if (!isset($this->data['openid_return_to'], $this->data['openid_realm'])) {
$this->errorResponse();
}
$realm = str_replace('\*', '[^/]', preg_quote($this->data['openid_realm']));
if(!preg_match("#^$realm#", $this->data['openid_return_to'])) {
$this->errorResponse();
}
}
protected function ax()
{
# Namespace prefix that the fields must have.
$ns = 'http://axschema.org/';
# First, we must find out what alias is used for AX.
# Let's check the most likely one
$alias = null;
if (isset($this->data['openid_ns_ax'])
&& $this->data['openid_ns_ax'] == 'http://openid.net/srv/ax/1.0'
) {
$alias = 'ax';
} else {
foreach($this->data as $name => $value) {
if ($value == 'http://openid.net/srv/ax/1.0'
&& preg_match('/openid_ns_(.+)/', $name, $m)
) {
$alias = $m[1];
break;
}
}
}
if(!$alias) {
return null;
}
$fields = array();
# Now, we must search again, this time for field aliases
foreach($this->data as $name => $value) {
if (strpos($name, 'openid_' . $alias . '_type') === false
|| strpos($value, $ns) === false) {
continue;
}
$name = substr($name, strlen('openid_' . $alias . '_type_'));
$value = substr($value, strlen($ns));
$fields[$name] = $value;
}
# Then, we find out what fields are required and optional
$required = array();
$if_available = array();
foreach(array('required','if_available') as $type) {
if(empty($this->data["openid_{$alias}_{$type}"])) {
continue;
}
$attributes = explode(',', $this->data["openid_{$alias}_{$type}"]);
foreach($attributes as $attr) {
if(empty($fields[$attr])) {
# There is an undefined field here, so we ignore it.
continue;
}
${$type}[] = $fields[$attr];
}
}
$this->data['ax'] = true;
return array('required' => $required, 'optional' => $if_available);
}
protected function sreg()
{
$sreg_to_ax = array_flip($this->ax_to_sreg);
$attributes = array('required' => array(), 'optional' => array());
if (empty($this->data['openid_sreg_required'])
&& empty($this->data['openid_sreg_optional'])
) {
return $attributes;
}
foreach(array('required', 'optional') as $type) {
foreach(explode(',',$this->data['openid_sreg_' . $type]) as $attr) {
if(empty($sreg_to_ax[$attr])) {
# Undefined attribute in SREG request.
# Shouldn't happen, but we check anyway.
continue;
}
$attributes[$type][] = $sreg_to_ax[$attr];
}
}
return $attributes;
}
/**
* Aids an RP in assertion verification.
* @return bool Information whether the verification suceeded.
*/
protected function verify()
{
# Firstly, we need to make sure that there's an association.
# Otherwise the verification will fail,
# because we've signed assoc_handle in the assertion
if(empty($this->assoc)) {
return false;
}
# Next, we check that it's a private association,
# i.e. one made without RP input.
# Otherwise, the RP shouldn't ask us to verify.
if(empty($this->assoc['private'])) {
return false;
}
# Now we have to check if the nonce is correct, to prevent replay attacks.
if($this->data['openid_response_nonce'] != $this->assoc['nonce']) {
return false;
}
# Getting the signed fields for signature.
$sig = array();
$signed = explode(',', $this->data['openid_signed']);
foreach($signed as $field) {
$name = strtr($field, '.', '_');
if(!isset($this->data['openid_' . $name])) {
return false;
}
$sig[$field] = $this->data['openid_' . $name];
}
# Computing the signature and checking if it matches.
$sig = $this->keyValueForm($sig);
if ($this->data['openid_sig'] !=
base64_encode(hash_hmac($this->assoc['hash'], $sig, $this->assoc['mac'], true))
) {
return false;
}
# Clearing the nonce, so that it won't be used again.
$this->assoc['nonce'] = null;
if(empty($this->assoc['private'])) {
# Commiting changes to the association.
$this->setAssoc($this->assoc['handle'], $this->assoc);
} else {
# Private associations shouldn't be used again, se we can as well delete them.
$this->delAssoc($this->assoc['handle']);
}
# Nothing has failed, so the verification was a success.
return true;
}
/**
* Performs association with an RP.
*/
protected function associate()
{
# Rejecting no-encryption without TLS.
if(empty($_SERVER['HTTPS']) && $this->data['openid_session_type'] == 'no-encryption') {
$this->directErrorResponse();
}
# Checking whether we support DH at all.
if (!$this->dh && substr($this->data['openid_session_type'], 0, 2) == 'DH') {
$this->redirect($this->response(array(
'openid.error' => 'DH not supported',
'openid.error_code' => 'unsupported-type',
'openid.session_type' => 'no-encryption'
)));
}
# Creating the association
$this->assoc = array();
$this->assoc['hash'] = $this->data['openid_assoc_type'] == 'HMAC-SHA256' ? 'sha256' : 'sha1';
$this->assoc['handle'] = $this->assoc_handle();
# Getting the shared secret
if($this->data['openid_session_type'] == 'no-encryption') {
$this->assoc['mac'] = base64_encode($this->shared_secret($this->assoc['hash']));
} else {
$this->dh();
}
# Preparing the direct response...
$response = array(
'ns' => $this->ns,
'assoc_handle' => $this->assoc['handle'],
'assoc_type' => $this->data['openid_assoc_type'],
'session_type' => $this->data['openid_session_type'],
'expires_in' => $this->assoc_lifetime
);
if(isset($this->assoc['dh_server_public'])) {
$response['dh_server_public'] = $this->assoc['dh_server_public'];
$response['enc_mac_key'] = $this->assoc['mac'];
} else {
$response['mac_key'] = $this->assoc['mac'];
}
# ...and sending it.
echo $this->keyValueForm($response);
die();
}
/**
* Creates a private association.
*/
protected function generateAssociation()
{
$this->assoc = array();
# We use sha1 by default.
$this->assoc['hash'] = 'sha1';
$this->assoc['mac'] = $this->shared_secret('sha1');
$this->assoc['handle'] = $this->assoc_handle();
}
/**
* Encrypts the MAC key using DH key exchange.
*/
protected function dh()
{
if(empty($this->data['openid_dh_modulus'])) {
$this->data['openid_dh_modulus'] = $this->default_modulus;
}
if(empty($this->data['openid_dh_gen'])) {
$this->data['openid_dh_gen'] = $this->default_gen;
}
if(empty($this->data['openid_dh_consumer_public'])) {
$this->directErrorResponse();
}
$modulus = $this->b64dec($this->data['openid_dh_modulus']);
$gen = $this->b64dec($this->data['openid_dh_gen']);
$consumerKey = $this->b64dec($this->data['openid_dh_consumer_public']);
$privateKey = $this->keygen(strlen($modulus));
$publicKey = $this->powmod($gen, $privateKey, $modulus);
$ss = $this->powmod($consumerKey, $privateKey, $modulus);
$mac = $this->x_or(hash($this->assoc['hash'], $ss, true), $this->shared_secret($this->assoc['hash']));
$this->assoc['dh_server_public'] = $this->decb64($publicKey);
$this->assoc['mac'] = base64_encode($mac);
}
/**
* XORs two strings.
* @param String $a
* @param String $b
* @return String $a ^ $b
*/
protected function x_or($a, $b)
{
$length = strlen($a);
for($i = 0; $i < $length; $i++) {
$a[$i] = $a[$i] ^ $b[$i];
}
return $a;
}
/**
* Prepares an indirect response url.
* @param array $params Parameters to be sent.
*/
protected function response($params)
{
$params += array('openid.ns' => $this->ns);
return $this->data['openid_return_to']
. (strpos($this->data['openid_return_to'],'?') ? '&' : '?')
. http_build_query($params, '', '&');
}
/**
* Outputs a direct error.
*/
protected function errorResponse()
{
if(!empty($this->data['openid_return_to'])) {
$response = array(
'openid.mode' => 'error',
'openid.error' => 'Invalid request'
);
$this->redirect($this->response($response));
} else {
header('HTTP/1.1 400 Bad Request');
$response = array(
'ns' => $this->ns,
'error' => 'Invalid request'
);
echo $this->keyValueForm($response);
}
die();
}
/**
* Sends an positive assertion.
* @param String $identity the OP-Local Identifier that is being authenticated.
* @param Array $attributes User attributes to be sent.
*/
protected function positiveResponse($identity, $attributes)
{
# We generate a private association if there is none established.
if(!$this->assoc) {
$this->generateAssociation();
$this->assoc['private'] = true;
}
# We set openid.identity (and openid.claimed_id if necessary) to our $identity
if($this->data['openid_identity'] == $this->data['openid_claimed_id'] || $this->select_id) {
$this->data['openid_claimed_id'] = $identity;
}
$this->data['openid_identity'] = $identity;
# Preparing fields to be signed
$params = array(
'op_endpoint' => $this->serverLocation,
'claimed_id' => $this->data['openid_claimed_id'],
'identity' => $this->data['openid_identity'],
'return_to' => $this->data['openid_return_to'],
'realm' => $this->data['openid_realm'],
'response_nonce' => gmdate("Y-m-d\TH:i:s\Z"),
'assoc_handle' => $this->assoc['handle'],
);
$params += $this->responseAttributes($attributes);
# Has the RP used an invalid association handle?
if (isset($this->data['openid_assoc_handle'])
&& $this->data['openid_assoc_handle'] != $this->assoc['handle']
) {
$params['invalidate_handle'] = $this->data['openid_assoc_handle'];
}
# Signing the $params
$sig = hash_hmac($this->assoc['hash'], $this->keyValueForm($params), $this->assoc['mac'], true);
$req = array(
'openid.mode' => 'id_res',
'openid.signed' => implode(',', array_keys($params)),
'openid.sig' => base64_encode($sig),
);
# Saving the nonce and commiting the association.
$this->assoc['nonce'] = $params['response_nonce'];
$this->setAssoc($this->assoc['handle'], $this->assoc);
# Preparing and sending the response itself
foreach($params as $name => $value) {
$req['openid.' . $name] = $value;
}
$this->redirect($this->response($req));
}
/**
* Prepares an array of attributes to send
*/
protected function responseAttributes($attributes)
{
if(!$attributes) return array();
$ns = 'http://axschema.org/';
$response = array();
if(isset($this->data['ax'])) {
$response['ns.ax'] = 'http://openid.net/srv/ax/1.0';
foreach($attributes as $name => $value) {
$alias = strtr($name, '/', '_');
$response['ax.type.' . $alias] = $ns . $name;
$response['ax.value.' . $alias] = $value;
}
return $response;
}
foreach($attributes as $name => $value) {
if(!isset($this->ax_to_sreg[$name])) {
continue;
}
$response['sreg.' . $this->ax_to_sreg[$name]] = $value;
}
return $response;
}
/**
* Encodes fields in key-value form.
* @param Array $params Fields to be encoded.
* @return String $params in key-value form.
*/
protected function keyValueForm($params)
{
$str = '';
foreach($params as $name => $value) {
$str .= "$name:$value\n";
}
return $str;
}
/**
* Responds with an information that the user has canceled authentication.
*/
protected function cancel()
{
$this->redirect($this->response(array('openid.mode' => 'cancel')));
}
/**
* Converts base64 encoded number to it's decimal representation.
* @param String $str base64 encoded number.
* @return String Decimal representation of that number.
*/
protected function b64dec($str)
{
$bytes = unpack('C*', base64_decode($str));
$n = 0;
foreach($bytes as $byte) {
$n = $this->add($this->mul($n, 256), $byte);
}
return $n;
}
/**
* Complements b64dec.
*/
protected function decb64($num)
{
$bytes = array();
while($num) {
array_unshift($bytes, $this->mod($num, 256));
$num = $this->div($num, 256);
}
if($bytes && $bytes[0] > 127) {
array_unshift($bytes,0);
}
array_unshift($bytes, 'C*');
return base64_encode(call_user_func_array('pack', $bytes));
}
function __call($name, $args)
{
switch($name) {
case 'add':
case 'mul':
case 'pow':
case 'mod':
case 'div':
case 'powmod':
if(function_exists('gmp_strval')) {
return gmp_strval(call_user_func_array($this->$name, $args));
}
return call_user_func_array($this->$name, $args);
default:
throw new BadMethodCallException();
}
}
}
