<?php

/* For licensing terms, see /license.txt */
/**
 * OpenID login method
 *
 * The OpenID login method relies on authentication servers providing a public
 * URL that can confirm the identity of a person, thus avoiding the spread
 * use of password transmissions over non-secure lines (for Dokeos, it is a
 * good way of avoiding password theft)
 * @package chamilo.auth.openid
 */

require_once 'openid.lib.php';
require_once 'xrds.lib.php';

function openid_form()
{
    $form = new FormValidator(
        'openid_login',
        'post',
        null,
        null,
        array('class' => 'form-vertical form_login')
    );
    $form -> addElement('text', 'openid_url', array(get_lang('OpenIDURL'), Display::url(get_lang('OpenIDWhatIs'), 'main/auth/openid/whatis.php')), array('class' => 'openid_input'));
    $form -> addElement('button', 'submit', get_lang('Login'));

    return $form->returnForm();
}

/**
 * The initial step of OpenID authentication responsible for the following:
 *  - Perform discovery on the claimed OpenID.
 *  - If possible, create an association with the Provider's endpoint.
 *  - Create the authentication request.
 *  - Perform the appropriate redirect.
 *
 * @param $claimed_id The OpenID to authenticate
 * @param $return_to The endpoint to return to from the OpenID Provider
 */
function openid_begin($claimed_id, $return_to = '', $form_values = array()) {

    $claimed_id = _openid_normalize($claimed_id);
    $services = openid_discovery($claimed_id);
    if (count($services) == 0) {
        echo 'Sorry, that is not a valid OpenID. Please ensure you have spelled your ID correctly.';
        return;
    }
    $op_endpoint = $services[0]['uri'];
    // Store the discovered endpoint in the session (so we don't have to rediscover).
    $_SESSION['openid_op_endpoint'] = $op_endpoint;
    // Store the claimed_id in the session (for handling delegation).
    $_SESSION['openid_claimed_id'] = $claimed_id;
    // Store the login form values so we can pass them to
    // user_exteral_login later.
    $_SESSION['openid_user_login_values'] = $form_values;

    // If bcmath is present, then create an association
    $assoc_handle = '';
    if (function_exists('bcadd')) {
        $assoc_handle = openid_association($op_endpoint);
    }
    // Now that there is an association created, move on
    // to request authentication from the IdP
    $identity = (!empty($services[0]['delegate'])) ? $services[0]['delegate'] : $claimed_id;
    if (isset($services[0]['types']) && is_array($services[0]['types']) && in_array(OPENID_NS_2_0 . '/server', $services[0]['types'])) {
        $identity = 'http://openid.net/identifier_select/2.0';
    }
    $authn_request = openid_authentication_request($claimed_id, $identity, $return_to, $assoc_handle, $services[0]['version']);
    if ($services[0]['version'] == 2) {
        echo openid_redirect($op_endpoint, $authn_request);
    } else {
        echo openid_redirect_http($op_endpoint, $authn_request);
    }
}

/**
 * Completes OpenID authentication by validating returned data from the OpenID
 * Provider.
 * @param array $response Array of returned from the OpenID provider (typically $_REQUEST).
 * @return array $response Response values for further processing with $response['status'] set to one of 'success', 'failed' or 'cancel'.
 */
function openid_complete($response) {
    // Default to failed response
    $response['status'] = 'failed';
    if (isset($_SESSION['openid_op_endpoint']) && isset($_SESSION['openid_claimed_id'])) {
        _openid_fix_post($response);
        $op_endpoint = $_SESSION['openid_op_endpoint'];
        $claimed_id = $_SESSION['openid_claimed_id'];
        unset($_SESSION['openid_op_endpoint']);
        unset($_SESSION['openid_claimed_id']);
        if (isset($response['openid.mode'])) {
            if ($response['openid.mode'] == 'cancel') {
                $response['status'] = 'cancel';
            } else {
                if (openid_verify_assertion($op_endpoint, $response)) {
                    $response['openid.identity'] = $claimed_id;
                    $response['status'] = 'success';
                }
            }
        }
    }

    return $response;
}

/**
 * Perform discovery on a claimed ID to determine the OpenID provider endpoint.
 *
 * @param $claimed_id The OpenID URL to perform discovery on.
 *
 * @return Array of services discovered (including OpenID version, endpoint
 * URI, etc).
 */
function openid_discovery($claimed_id)
{
    $services = array();

    $xrds_url = $claimed_id;
    if (_openid_is_xri($claimed_id)) {
        $xrds_url = 'http://xri.net/' . $claimed_id;
    }
    $url = @parse_url($xrds_url);
    if ($url['scheme'] == 'http' || $url['scheme'] == 'https') {
        // For regular URLs, try Yadis resolution first, then HTML-based discovery
        $headers = array('Accept' => 'application/xrds+xml');
        //TODO
        $result = openid_http_request($xrds_url, $headers);

        if (!isset($result->error)) {
            if (isset($result->headers['Content-Type']) && preg_match("/application\/xrds\+xml/", $result->headers['Content-Type'])) {
                // Parse XML document to find URL
                $services = xrds_parse($result->data);
            } else {
                $xrds_url = NULL;
                if (isset($result->headers['X-XRDS-Location'])) {
                    $xrds_url = $result->headers['X-XRDS-Location'];
                } else {
                    // Look for meta http-equiv link in HTML head
                    $xrds_url = _openid_meta_httpequiv('X-XRDS-Location', $result->data);
                }
                if (!empty($xrds_url)) {
                    $headers = array('Accept' => 'application/xrds+xml');
                    //TODO
                    $xrds_result = openid_http_request($xrds_url, $headers);
                    if (!isset($xrds_result->error)) {
                        $services = xrds_parse($xrds_result->data);
                    }
                }
            }

            // Check for HTML delegation
            if (count($services) == 0) {
                // Look for 2.0 links
                $uri = _openid_link_href('openid2.provider', $result->data);
                $delegate = _openid_link_href('openid2.local_id', $result->data);
                $version = 2;

                // 1.0 links
                if (empty($uri)) {
                    $uri = _openid_link_href('openid.server', $result->data);
                    $delegate = _openid_link_href('openid.delegate', $result->data);
                    $version = 1;
                }
                if (!empty($uri)) {
                    $services[] = array('uri' => $uri, 'delegate' => $delegate, 'version' => $version);
                }
            }
        }
    }

    return $services;
}

/**
 * Attempt to create a shared secret with the OpenID Provider.
 * @param $op_endpoint URL of the OpenID Provider endpoint.
 * @return object $assoc_handle The association handle.
 */
function openid_association($op_endpoint) {
    //@todo Remove Old Associations:
    $openid_association = Database::get_main_table(TABLE_MAIN_OPENID_ASSOCIATION);
    $sql = "DELETE FROM $openid_association
            WHERE created + expires_in < '" . api_get_utc_datetime() . "'";
    Database::query($sql);

    // Check to see if we have an association for this IdP already
    $op_endpoint = Database::escape_string($op_endpoint);
    $sql = "SELECT assoc_handle
            FROM $openid_association
            WHERE idp_endpoint_uri = '$op_endpoint'";
    $assoc_handle = Database::query($sql);
    if (Database::num_rows($assoc_handle) <= 1) {
        $mod = OPENID_DH_DEFAULT_MOD;
        $gen = OPENID_DH_DEFAULT_GEN;
        $r = _openid_dh_rand($mod);
        $private = bcadd($r, 1);
        $public = bcpowmod($gen, $private, $mod);

        // If there is no existing association, then request one
        $assoc_request = openid_association_request($public);
        $assoc_message = _openid_encode_message(_openid_create_message($assoc_request));
        $assoc_headers = array('Content-Type' => 'application/x-www-form-urlencoded; charset=utf-8');
        //TODO
        $assoc_result = openid_http_request($op_endpoint, $assoc_headers, 'POST', $assoc_message);
        if (isset($assoc_result->error)) {
            return FALSE;
        }

        $assoc_response = _openid_parse_message($assoc_result->data);
        if (isset($assoc_response['mode']) && $assoc_response['mode'] == 'error') {
            return FALSE;
        }

        if ($assoc_response['session_type'] == 'DH-SHA1') {
            $spub = _openid_dh_base64_to_long($assoc_response['dh_server_public']);
            $enc_mac_key = base64_decode($assoc_response['enc_mac_key']);
            $shared = bcpowmod($spub, $private, $mod);
            $assoc_response['mac_key'] = base64_encode(_openid_dh_xorsecret($shared, $enc_mac_key));
        }
        //TODO
        $openid_association = Database::get_main_table(TABLE_MAIN_OPENID_ASSOCIATION);
        Database::query(sprintf("INSERT INTO $openid_association (idp_endpoint_uri, session_type, assoc_handle, assoc_type, expires_in, mac_key, created) VALUES('%s', '%s', '%s', '%s', %d, '%s', %d)", $op_endpoint, $assoc_response['session_type'], $assoc_response['assoc_handle'], $assoc_response['assoc_type'], $assoc_response['expires_in'], $assoc_response['mac_key'], api_get_utc_datetime()));

        $assoc_handle = $assoc_response['assoc_handle'];
    }
    return $assoc_handle;
}

/**
 * ?
 */
function openid_association_request($public) {

    $request = array(
        'openid.ns' => OPENID_NS_2_0,
        'openid.mode' => 'associate',
        'openid.session_type' => 'DH-SHA1',
        'openid.assoc_type' => 'HMAC-SHA1'
    );

    if ($request['openid.session_type'] == 'DH-SHA1' || $request['openid.session_type'] == 'DH-SHA256') {
        $cpub = _openid_dh_long_to_base64($public);
        $request['openid.dh_consumer_public'] = $cpub;
    }

    return $request;
}

/**
 *
 */
function openid_authentication_request($claimed_id, $identity, $return_to = '', $assoc_handle = '', $version = 2) {

    $realm = ($return_to) ? $return_to : api_get_self();

    $ns = ($version == 2) ? OPENID_NS_2_0 : OPENID_NS_1_0;
    $request = array(
        'openid.ns' => $ns,
        'openid.mode' => 'checkid_setup',
        'openid.identity' => $identity,
        'openid.claimed_id' => $claimed_id,
        'openid.assoc_handle' => $assoc_handle,
        'openid.return_to' => $return_to,
    );

    if ($version == 2) {
        $request['openid.realm'] = $realm;
    } else {
        $request['openid.trust_root'] = $realm;
    }

    // Simple Registration - we don't ask lastname and firstname because the only
    // available similar data is "fullname" and we would have to guess where to split
    $request['openid.sreg.required'] = 'nickname,email';
    $request['openid.ns.sreg'] = "http://openid.net/extensions/sreg/1.1";

    //$request = array_merge($request, module_invoke_all('openid', 'request', $request));
    //$request = array_merge($request);

    return $request;
}

/**
 * Attempt to verify the response received from the OpenID Provider.
 *
 * @param $op_endpoint The OpenID Provider URL.
 * @param $response Array of repsonse values from the provider.
 *
 * @return boolean
 */
function openid_verify_assertion($op_endpoint, $response) {

    $valid = FALSE;

    //TODO
    $openid_association = Database::get_main_table(TABLE_MAIN_OPENID_ASSOCIATION);
    $sql = sprintf("SELECT * FROM $openid_association WHERE assoc_handle = '%s'", $response['openid.assoc_handle']);
    $res = Database::query($sql);
    $association = Database::fetch_object($res);
    if ($association && isset($association->session_type)) {
        $keys_to_sign = explode(',', $response['openid.signed']);
        $self_sig = _openid_signature($association, $response, $keys_to_sign);
        if ($self_sig == $response['openid.sig']) {
            $valid = TRUE;
        } else {
            $valid = FALSE;
        }
    } else {
        $request = $response;
        $request['openid.mode'] = 'check_authentication';
        $message = _openid_create_message($request);
        $headers = array('Content-Type' => 'application/x-www-form-urlencoded; charset=utf-8');
        $result = openid_http_request($op_endpoint, $headers, 'POST', _openid_encode_message($message));
        if (!isset($result->error)) {
            $response = _openid_parse_message($result->data);
            if (strtolower(trim($response['is_valid'])) == 'true') {
                $valid = TRUE;
            } else {
                $valid = FALSE;
            }
        }
    }

    return $valid;
}

/**
 * Make a HTTP request - This function has been copied straight over from Drupal 6 code (drupal_http_request)
 * @param string $data
 */
function openid_http_request($url, $headers = array(), $method = 'GET', $data = NULL, $retry = 3) {
    $result = new stdClass();

    // Parse the URL and make sure we can handle the schema.
    $uri = parse_url($url);

    switch ($uri['scheme']) {
        case 'http':
            $port = isset($uri['port']) ? $uri['port'] : 80;
            $host = $uri['host'] . ($port != 80 ? ':' . $port : '');
            $fp = @fsockopen($uri['host'], $port, $errno, $errstr, 15);
            break;
        case 'https':
            // Note: Only works for PHP 4.3 compiled with OpenSSL.
            $port = isset($uri['port']) ? $uri['port'] : 443;
            $host = $uri['host'] . ($port != 443 ? ':' . $port : '');
            $fp = @fsockopen('ssl://' . $uri['host'], $port, $errno, $errstr, 20);
            break;
        default:
            $result->error = 'invalid schema ' . $uri['scheme'];
            return $result;
    }

    // Make sure the socket opened properly.
    if (!$fp) {
        // When a network error occurs, we make sure that it is a negative number so
        // it can clash with the HTTP status codes.
        $result->code = -$errno;
        $result->error = trim($errstr);
        return $result;
    }

    // Construct the path to act on.
    $path = isset($uri['path']) ? $uri['path'] : '/';
    if (isset($uri['query'])) {
        $path .= '?' . $uri['query'];
    }

    // Create HTTP request.
    $defaults = array(
        // RFC 2616: "non-standard ports MUST, default ports MAY be included".
        // We don't add the port to prevent from breaking rewrite rules checking the
        // host that do not take into account the port number.
        'Host' => "Host: $host",
        'User-Agent' => 'User-Agent: Chamilo (+http://www.chamilo.org/)',
        'Content-Length' => 'Content-Length: ' . strlen($data)
    );

    // If the server url has a user then attempt to use basic authentication
    if (isset($uri['user'])) {
        $defaults['Authorization'] = 'Authorization: Basic ' . base64_encode($uri['user'] . (!empty($uri['pass']) ? ":" . $uri['pass'] : ''));
    }

    foreach ($headers as $header => $value) {
        $defaults[$header] = $header . ': ' . $value;
    }

    $request = $method . ' ' . $path . " HTTP/1.0\r\n";
    $request .= implode("\r\n", $defaults);
    $request .= "\r\n\r\n";
    if ($data) {
        $request .= $data . "\r\n";
    }
    $result->request = $request;

    fwrite($fp, $request);

    // Fetch response.
    $response = '';
    while (!feof($fp) && $chunk = fread($fp, 1024)) {
        $response .= $chunk;
    }
    fclose($fp);

    // Parse response.
    list($split, $result->data) = explode("\r\n\r\n", $response, 2);
    $split = preg_split("/\r\n|\n|\r/", $split);

    list($protocol, $code, $text) = explode(' ', trim(array_shift($split)), 3);
    $result->headers = array();

    // Parse headers.
    while ($line = trim(array_shift($split))) {
        list($header, $value) = explode(':', $line, 2);
        if (isset($result->headers[$header]) && $header == 'Set-Cookie') {
            // RFC 2109: the Set-Cookie response header comprises the token Set-
            // Cookie:, followed by a comma-separated list of one or more cookies.
            $result->headers[$header] .= ',' . trim($value);
        } else {
            $result->headers[$header] = trim($value);
        }
    }

    $responses = array(
        100 => 'Continue', 101 => 'Switching Protocols',
        200 => 'OK', 201 => 'Created', 202 => 'Accepted', 203 => 'Non-Authoritative Information', 204 => 'No Content', 205 => 'Reset Content', 206 => 'Partial Content',
        300 => 'Multiple Choices', 301 => 'Moved Permanently', 302 => 'Found', 303 => 'See Other', 304 => 'Not Modified', 305 => 'Use Proxy', 307 => 'Temporary Redirect',
        400 => 'Bad Request', 401 => 'Unauthorized', 402 => 'Payment Required', 403 => 'Forbidden', 404 => 'Not Found', 405 => 'Method Not Allowed', 406 => 'Not Acceptable', 407 => 'Proxy Authentication Required', 408 => 'Request Time-out', 409 => 'Conflict', 410 => 'Gone', 411 => 'Length Required', 412 => 'Precondition Failed', 413 => 'Request Entity Too Large', 414 => 'Request-URI Too Large', 415 => 'Unsupported Media Type', 416 => 'Requested range not satisfiable', 417 => 'Expectation Failed',
        500 => 'Internal Server Error', 501 => 'Not Implemented', 502 => 'Bad Gateway', 503 => 'Service Unavailable', 504 => 'Gateway Time-out', 505 => 'HTTP Version not supported'
    );
    // RFC 2616 states that all unknown HTTP codes must be treated the same as the
    // base code in their class.
    if (!isset($responses[$code])) {
        $code = floor($code / 100) * 100;
    }

    switch ($code) {
        case 200: // OK
        case 304: // Not modified
            break;
        case 301: // Moved permanently
        case 302: // Moved temporarily
        case 307: // Moved temporarily
            $location = $result->headers['Location'];

            if ($retry) {
                $result = openid_http_request($result->headers['Location'], $headers, $method, $data, --$retry);
                $result->redirect_code = $result->code;
            }
            $result->redirect_url = $location;

            break;
        default:
            $result->error = $text;
    }

    $result->code = $code;
    return $result;
}