<?php

/**
 * @file
 * Dummy OpenID Provider used with SimpleTest.
 *
 * The provider simply responds positively to all authentication requests. In
 * addition to a Provider Endpoint (a URL used for Drupal to communicate with
 * the provider using the OpenID Authentication protocol) the module provides
 * URLs used by the various discovery mechanisms.
 *
 * When a user enters an OpenID identity, the Relying Party (in the testing
 * scenario, this is the OpenID module) looks up the URL of the Provider
 * Endpoint using one of several discovery mechanisms. The Relying Party then
 * redirects the user to Provider Endpoint. The provider verifies the user's
 * identity and redirects the user back to the Relying Party accompanied by a
 * signed message confirming the identity. Before redirecting to a provider for
 * the first time, the Relying Party fetches a secret MAC key from the provider
 * by doing a direct "associate" HTTP request to the Provider Endpoint. This
 * key is used for verifying the signed messages from the provider.
 */

/**
 * Implements hook_menu().
 */
function openid_test_menu() {
  $items['openid-test/yadis/xrds'] = array(
    'title' => 'XRDS service document',
    'page callback' => 'openid_test_yadis_xrds',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['openid-test/yadis/x-xrds-location'] = array(
    'title' => 'Yadis discovery using X-XRDS-Location header',
    'page callback' => 'openid_test_yadis_x_xrds_location',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['openid-test/yadis/http-equiv'] = array(
    'title' => 'Yadis discovery using <meta http-equiv="X-XRDS-Location" ...>',
    'page callback' => 'openid_test_yadis_http_equiv',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['openid-test/html/openid1'] = array(
    'title' => 'HTML-based discovery using <link rel="openid.server" ...>',
    'page callback' => 'openid_test_html_openid1',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['openid-test/html/openid2'] = array(
    'title' => 'HTML-based discovery using <link rel="openid2.provider" ...>',
    'page callback' => 'openid_test_html_openid2',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['openid-test/endpoint'] = array(
    'title' => 'OpenID Provider Endpoint',
    'page callback' => 'openid_test_endpoint',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['openid-test/redirect'] = array(
    'title' => 'OpenID Provider Redirection Point',
    'page callback' => 'openid_test_redirect',
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  $items['openid-test/redirected/%/%'] = array(
    'title' => 'OpenID Provider Final URL',
    'page callback' => 'openid_test_redirected_method',
    'page arguments' => array(2, 3),
    'access callback' => TRUE,
    'type' => MENU_CALLBACK,
  );
  return $items;
}

/**
 * Implements hook_menu_site_status_alter().
 */
function openid_test_menu_site_status_alter(&$menu_site_status, $path) {
  // Allow access to openid endpoint and identity even in offline mode.
  if ($menu_site_status == MENU_SITE_OFFLINE && user_is_anonymous() && in_array($path, array('openid-test/yadis/xrds', 'openid-test/endpoint'))) {
    $menu_site_status = MENU_SITE_ONLINE;
  }
}

/**
 * Menu callback; XRDS document that references the OP Endpoint URL.
 */
function openid_test_yadis_xrds() {
  if ($_SERVER['HTTP_ACCEPT'] == 'application/xrds+xml') {
    // Only respond to XRI requests for one specific XRI. The is used to verify
    // that the XRI has been properly encoded. The "+" sign in the _xrd_r query
    // parameter is decoded to a space by PHP.
    if (arg(3) == 'xri') {
      if (variable_get('clean_url', 0)) {
        if (arg(4) != '@example*résumé;%25' || $_GET['_xrd_r'] != 'application/xrds xml') {
          drupal_not_found();
        }
      }
      else {
        // Drupal cannot properly emulate an XRI proxy resolver using unclean
        // URLs, so the arguments gets messed up.
        if (arg(4) . '/' . arg(5) != '@example*résumé;%25?_xrd_r=application/xrds xml') {
          drupal_not_found();
        }
      }
    }
    drupal_add_http_header('Content-Type', 'application/xrds+xml');
    print '<?xml version="1.0" encoding="UTF-8"?>';
    if (!empty($_GET['doctype'])) {
      print "\n<!DOCTYPE dct [ <!ELEMENT blue (#PCDATA)> ]>\n";
    }
    print '
      <xrds:XRDS xmlns:xrds="xri://$xrds" xmlns="xri://$xrd*($v*2.0)" xmlns:openid="http://openid.net/xmlns/1.0">
        <XRD>
          <Status cid="' . check_plain(variable_get('openid_test_canonical_id_status', 'verified')) . '"/>
          <ProviderID>xri://@</ProviderID>
          <CanonicalID>http://example.com/user</CanonicalID>
          <Service>
            <Type>http://example.com/this-is-ignored</Type>
          </Service>
          <Service priority="5">
            <Type>http://openid.net/signon/1.0</Type>
            <URI>http://example.com/this-is-only-openid-1.0</URI>
          </Service>
          <Service priority="10">
            <Type>http://specs.openid.net/auth/2.0/signon</Type>
            <Type>http://openid.net/srv/ax/1.0</Type>
            <URI>' . url('openid-test/endpoint', array('absolute' => TRUE)) . '</URI>
            <LocalID>http://example.com/xrds</LocalID>
          </Service>
          <Service priority="15">
            <Type>http://specs.openid.net/auth/2.0/signon</Type>
            <URI>http://example.com/this-has-too-low-priority</URI>
          </Service>
          <Service>
            <Type>http://specs.openid.net/auth/2.0/signon</Type>
            <URI>http://example.com/this-has-too-low-priority</URI>
          </Service>
          ';
    if (arg(3) == 'server') {
      print '
          <Service>
            <Type>http://specs.openid.net/auth/2.0/server</Type>
            <URI>http://example.com/this-has-too-low-priority</URI>
          </Service>
          <Service priority="20">
            <Type>http://specs.openid.net/auth/2.0/server</Type>
            <URI>' . url('openid-test/endpoint', array('absolute' => TRUE)) . '</URI>
            <LocalID>' . url('openid-test/yadis/xrds/server', array('absolute' => TRUE)) . '</LocalID>
          </Service>';
    }
    elseif (arg(3) == 'delegate') {
      print '
          <Service priority="0">
            <Type>http://specs.openid.net/auth/2.0/signon</Type>
            <Type>http://openid.net/srv/ax/1.0</Type>
            <URI>' . url('openid-test/endpoint', array('absolute' => TRUE)) . '</URI>
            <openid:Delegate>http://example.com/xrds-delegate</openid:Delegate>
          </Service>';
    }
    print '
        </XRD>
      </xrds:XRDS>';
  }
  else {
    return t('This is a regular HTML page. If the client sends an Accept: application/xrds+xml header when requesting this URL, an XRDS document is returned.');
  }
}

/**
 * Menu callback; regular HTML page with an X-XRDS-Location HTTP header.
 */
function openid_test_yadis_x_xrds_location() {
  drupal_add_http_header('X-XRDS-Location', url('openid-test/yadis/xrds', array('absolute' => TRUE)));
  return t('This page includes an X-RDS-Location HTTP header containing the URL of an XRDS document.');
}

/**
 * Menu callback; regular HTML page with <meta> element.
 */
function openid_test_yadis_http_equiv() {
  $element = array(
    '#tag' => 'meta',
    '#attributes' => array(
      'http-equiv' => 'X-XRDS-Location',
      'content' => url('openid-test/yadis/xrds', array('absolute' => TRUE)),
    ),
  );
  drupal_add_html_head($element, 'openid_test_yadis_http_equiv');
  return t('This page includes a &lt;meta equiv=...&gt; element containing the URL of an XRDS document.');
}

/**
 * Menu callback; regular HTML page with OpenID 1.0 <link> element.
 */
function openid_test_html_openid1() {
  drupal_add_html_head_link(array('rel' => 'openid.server', 'href' => url('openid-test/endpoint', array('absolute' => TRUE))));
  drupal_add_html_head_link(array('rel' => 'openid.delegate', 'href' => 'http://example.com/html-openid1'));
  return t('This page includes a &lt;link rel=...&gt; element containing the URL of an OpenID Provider Endpoint.');
}

/**
 * Menu callback; regular HTML page with OpenID 2.0 <link> element.
 */
function openid_test_html_openid2() {
  drupal_add_html_head_link(array('rel' => 'openid2.provider', 'href' => url('openid-test/endpoint', array('absolute' => TRUE))));
  drupal_add_html_head_link(array('rel' => 'openid2.local_id', 'href' => 'http://example.com/html-openid2'));
  return t('This page includes a &lt;link rel=...&gt; element containing the URL of an OpenID Provider Endpoint.');
}

/**
 * Menu callback; OpenID Provider Endpoint.
 *
 * It accepts "associate" requests directly from the Relying Party, and
 * "checkid_setup" requests made by the user's browser based on HTTP redirects
 * (in OpenID 1) or HTML forms (in OpenID 2) generated by the Relying Party.
 */
function openid_test_endpoint() {
  switch ($_REQUEST['openid_mode']) {
    case 'associate':
      _openid_test_endpoint_associate();
      break;
    case 'checkid_setup':
      _openid_test_endpoint_authenticate();
      break;
  }
}

/**
 * Menu callback; redirect during Normalization/Discovery.
 */
function openid_test_redirect($count = 0) {
  if ($count == 0) {
    $url = variable_get('openid_test_redirect_url', '');
  }
  else {
    $url = url('openid-test/redirect/' . --$count, array('absolute' => TRUE));
  }
  $http_response_code = variable_get('openid_test_redirect_http_reponse_code', 301);
  header('Location: ' . $url, TRUE, $http_response_code);
  exit();
}

/**
 * Menu callback; respond with appropriate callback.
 */
function openid_test_redirected_method($method1, $method2) {
  return call_user_func('openid_test_' . $method1 . '_' . $method2);
}

/**
 * OpenID endpoint; handle "associate" requests (see OpenID Authentication 2.0,
 * section 8).
 *
 * The purpose of association is to send the secret MAC key to the Relying Party
 * using Diffie-Hellman key exchange. The MAC key is used in subsequent
 * "authenticate" requests. The "associate" request is made by the Relying Party
 * (in the testing scenario, this is the OpenID module that communicates with
 * the endpoint using drupal_http_request()).
 */
function _openid_test_endpoint_associate() {
  module_load_include('inc', 'openid');

  // Use default parameters for Diffie-Helmann key exchange.
  $mod = OPENID_DH_DEFAULT_MOD;
  $gen = OPENID_DH_DEFAULT_GEN;

  // Generate private Diffie-Helmann key.
  $r = _openid_dh_rand($mod);
  $private = _openid_math_add($r, 1);

  // Calculate public Diffie-Helmann key.
  $public = _openid_math_powmod($gen, $private, $mod);

  // Calculate shared secret based on Relying Party's public key.
  $cpub = _openid_dh_base64_to_long($_REQUEST['openid_dh_consumer_public']);
  $shared = _openid_math_powmod($cpub, $private, $mod);

  // Encrypt the MAC key using the shared secret.
  $enc_mac_key = base64_encode(_openid_dh_xorsecret($shared, base64_decode(variable_get('mac_key'))));

  // Generate response including our public key and the MAC key. Using our
  // public key and its own private key, the Relying Party can calculate the
  // shared secret, and with this it can decrypt the encrypted MAC key.
  $response = array(
    'ns' => 'http://specs.openid.net/auth/2.0',
    'assoc_handle' => 'openid-test',
    'session_type' => $_REQUEST['openid_session_type'],
    'assoc_type' => $_REQUEST['openid_assoc_type'],
    'expires_in' => '3600',
    'dh_server_public' => _openid_dh_long_to_base64($public),
    'enc_mac_key' => $enc_mac_key,
  );

  // Respond to Relying Party in the special Key-Value Form Encoding (see OpenID
  // Authentication 1.0, section 4.1.1).
  drupal_add_http_header('Content-Type', 'text/plain');
  print _openid_create_message($response);
}

/**
 * OpenID endpoint; handle "authenticate" requests.
 *
 * All requests result in a successful response. The request is a GET or POST
 * made by the user's browser based on an HTML form or HTTP redirect generated
 * by the Relying Party. The user is redirected back to the Relying Party using
 * a URL containing a signed message in the query string confirming the user's
 * identity.
 */
function _openid_test_endpoint_authenticate() {
  module_load_include('inc', 'openid');

  $expected_identity = variable_get('openid_test_identity');
  if ($expected_identity && $_REQUEST['openid_identity'] != $expected_identity) {
    $response = variable_get('openid_test_response', array()) + array(
      'openid.ns' => OPENID_NS_2_0,
      'openid.mode' => 'error',
      'openid.error' => 'Unexpted identity',
    );
    drupal_add_http_header('Content-Type', 'text/plain');
    header('Location: ' . url($_REQUEST['openid_return_to'], array('query' => $response, 'external' => TRUE)));
    return;
  }

  // Generate unique identifier for this authentication.
  $nonce = _openid_nonce();

  // Generate response containing the user's identity.
  $response = variable_get('openid_test_response', array()) + array(
    'openid.ns' => OPENID_NS_2_0,
    'openid.mode' => 'id_res',
    'openid.op_endpoint' => url('openid-test/endpoint', array('absolute' => TRUE)),
    'openid.claimed_id' => !empty($_REQUEST['openid_claimed_id']) ? $_REQUEST['openid_claimed_id'] : '',
    'openid.identity' => $_REQUEST['openid_identity'],
    'openid.return_to' => $_REQUEST['openid_return_to'],
    'openid.response_nonce' => $nonce,
    'openid.assoc_handle' => 'openid-test',
  );

  if (isset($response['openid.signed'])) {
    $keys_to_sign = explode(',', $response['openid.signed']);
  }
  else {
    // Unless openid.signed is explicitly defined, all keys are signed.
    $keys_to_sign = array();
    foreach ($response as $key => $value) {
      // Strip off the "openid." prefix.
      $keys_to_sign[] = substr($key, 7);
    }
    $response['openid.signed'] = implode(',', $keys_to_sign);
  }

  // Sign the message using the MAC key that was exchanged during association.
  $association = new stdClass();
  $association->mac_key = variable_get('mac_key');
  if (!isset($response['openid.sig'])) {
    $response['openid.sig'] = _openid_signature($association, $response, $keys_to_sign);
  }

  // Put the signed message into the query string of a URL supplied by the
  // Relying Party, and redirect the user.
  drupal_add_http_header('Content-Type', 'text/plain');
  header('Location: ' . url($_REQUEST['openid_return_to'], array('query' => $response, 'external' => TRUE)));
}
