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   1  <?php
   2  /**
   3   * An XML-RPC client
   4   *
   5   * @author  Donal McMullan  [email protected]
   6   * @version 0.0.1
   7   * @license http://www.gnu.org/copyleft/gpl.html GNU Public License
   8   * @package mnet
   9   */
  10  
  11  require_once $CFG->dirroot.'/mnet/lib.php';
  12  
  13  /**
  14   * Class representing an XMLRPC request against a remote machine
  15   */
  16  class mnet_xmlrpc_client {
  17  
  18      var $method   = '';
  19      var $params   = array();
  20      var $timeout  = 60;
  21      var $error    = array();
  22      var $response = '';
  23      var $mnet     = null;
  24  
  25      /**
  26       * Constructor returns true
  27       */
  28      function mnet_xmlrpc_client() {
  29          // make sure we've got this set up before we try and do anything else
  30          $this->mnet = get_mnet_environment();
  31          return true;
  32      }
  33  
  34      /**
  35       * Allow users to override the default timeout
  36       * @param   int $timeout    Request timeout in seconds
  37       * $return  bool            True if param is an integer or integer string
  38       */
  39      function set_timeout($timeout) {
  40          if (!is_integer($timeout)) {
  41              if (is_numeric($timeout)) {
  42                  $this->timeout = (integer)$timeout;
  43                  return true;
  44              }
  45              return false;
  46          }
  47          $this->timeout = $timeout;
  48          return true;
  49      }
  50  
  51      /**
  52       * Set the path to the method or function we want to execute on the remote
  53       * machine. Examples:
  54       * mod/scorm/functionname
  55       * auth/mnet/methodname
  56       * In the case of auth and enrolment plugins, an object will be created and
  57       * the method on that object will be called
  58       */
  59      function set_method($xmlrpcpath) {
  60          if (is_string($xmlrpcpath)) {
  61              $this->method = $xmlrpcpath;
  62              $this->params = array();
  63              return true;
  64          }
  65          $this->method = '';
  66          $this->params = array();
  67          return false;
  68      }
  69  
  70      /**
  71       * Add a parameter to the array of parameters.
  72       *
  73       * @param  string  $argument    A transport ID, as defined in lib.php
  74       * @param  string  $type        The argument type, can be one of:
  75       *                              none
  76       *                              empty
  77       *                              base64
  78       *                              boolean
  79       *                              datetime
  80       *                              double
  81       *                              int
  82       *                              string
  83       *                              array
  84       *                              struct
  85       *                              In its weakly-typed wisdom, PHP will (currently)
  86       *                              ignore everything except datetime and base64
  87       * @return bool                 True on success
  88       */
  89      function add_param($argument, $type = 'string') {
  90  
  91          $allowed_types = array('none',
  92                                 'empty',
  93                                 'base64',
  94                                 'boolean',
  95                                 'datetime',
  96                                 'double',
  97                                 'int',
  98                                 'i4',
  99                                 'string',
 100                                 'array',
 101                                 'struct');
 102          if (!in_array($type, $allowed_types)) {
 103              return false;
 104          }
 105  
 106          if ($type != 'datetime' && $type != 'base64') {
 107              $this->params[] = $argument;
 108              return true;
 109          }
 110  
 111          // Note weirdness - The type of $argument gets changed to an object with
 112          // value and type properties.
 113          // bool xmlrpc_set_type ( string &value, string type )
 114          xmlrpc_set_type($argument, $type);
 115          $this->params[] = $argument;
 116          return true;
 117      }
 118  
 119      /**
 120       * Send the request to the server - decode and return the response
 121       *
 122       * @param  object   $mnet_peer      A mnet_peer object with details of the
 123       *                                  remote host we're connecting to
 124       * @return mixed                    A PHP variable, as returned by the
 125       *                                  remote function
 126       */
 127      function send($mnet_peer) {
 128          global $CFG, $DB;
 129  
 130  
 131          if (!$this->permission_to_call($mnet_peer)) {
 132              mnet_debug("tried and wasn't allowed to call a method on $mnet_peer->wwwroot");
 133              return false;
 134          }
 135  
 136          $this->requesttext = xmlrpc_encode_request($this->method, $this->params, array("encoding" => "utf-8", "escaping" => "markup"));
 137          $this->signedrequest = mnet_sign_message($this->requesttext);
 138          $this->encryptedrequest = mnet_encrypt_message($this->signedrequest, $mnet_peer->public_key);
 139  
 140          $httprequest = $this->prepare_http_request($mnet_peer);
 141          curl_setopt($httprequest, CURLOPT_POSTFIELDS, $this->encryptedrequest);
 142  
 143          $timestamp_send    = time();
 144          mnet_debug("about to send the curl request");
 145          $this->rawresponse = curl_exec($httprequest);
 146          mnet_debug("managed to complete a curl request");
 147          $timestamp_receive = time();
 148  
 149          if ($this->rawresponse === false) {
 150              $this->error[] = curl_errno($httprequest) .':'. curl_error($httprequest);
 151              return false;
 152          }
 153          curl_close($httprequest);
 154  
 155          $this->rawresponse = trim($this->rawresponse);
 156  
 157          $mnet_peer->touch();
 158  
 159          $crypt_parser = new mnet_encxml_parser();
 160          $crypt_parser->parse($this->rawresponse);
 161  
 162          // If we couldn't parse the message, or it doesn't seem to have encrypted contents,
 163          // give the most specific error msg available & return
 164          if (!$crypt_parser->payload_encrypted) {
 165              if (! empty($crypt_parser->remoteerror)) {
 166                  $this->error[] = '4: remote server error: ' . $crypt_parser->remoteerror;
 167              } else if (! empty($crypt_parser->error)) {
 168                  $crypt_parser_error = $crypt_parser->error[0];
 169  
 170                  $message = '3:XML Parse error in payload: '.$crypt_parser_error['string']."\n";
 171                  if (array_key_exists('lineno', $crypt_parser_error)) {
 172                      $message .= 'At line number: '.$crypt_parser_error['lineno']."\n";
 173                  }
 174                  if (array_key_exists('line', $crypt_parser_error)) {
 175                      $message .= 'Which reads: '.$crypt_parser_error['line']."\n";
 176                  }
 177                  $this->error[] = $message;
 178              } else {
 179                  $this->error[] = '1:Payload not encrypted ';
 180              }
 181  
 182              $crypt_parser->free_resource();
 183              return false;
 184          }
 185  
 186          $key  = array_pop($crypt_parser->cipher);
 187          $data = array_pop($crypt_parser->cipher);
 188  
 189          $crypt_parser->free_resource();
 190  
 191          // Initialize payload var
 192          $decryptedenvelope = '';
 193  
 194          //                                          &$decryptedenvelope
 195          $isOpen = openssl_open(base64_decode($data), $decryptedenvelope, base64_decode($key), $this->mnet->get_private_key());
 196  
 197          if (!$isOpen) {
 198              // Decryption failed... let's try our archived keys
 199              $openssl_history = get_config('mnet', 'openssl_history');
 200              if(empty($openssl_history)) {
 201                  $openssl_history = array();
 202                  set_config('openssl_history', serialize($openssl_history), 'mnet');
 203              } else {
 204                  $openssl_history = unserialize($openssl_history);
 205              }
 206              foreach($openssl_history as $keyset) {
 207                  $keyresource = openssl_pkey_get_private($keyset['keypair_PEM']);
 208                  $isOpen      = openssl_open(base64_decode($data), $decryptedenvelope, base64_decode($key), $keyresource);
 209                  if ($isOpen) {
 210                      // It's an older code, sir, but it checks out
 211                      break;
 212                  }
 213              }
 214          }
 215  
 216          if (!$isOpen) {
 217              trigger_error("None of our keys could open the payload from host {$mnet_peer->wwwroot} with id {$mnet_peer->id}.");
 218              $this->error[] = '3:No key match';
 219              return false;
 220          }
 221  
 222          if (strpos(substr($decryptedenvelope, 0, 100), '<signedMessage>')) {
 223              $sig_parser = new mnet_encxml_parser();
 224              $sig_parser->parse($decryptedenvelope);
 225          } else {
 226              $this->error[] = '2:Payload not signed: ' . $decryptedenvelope;
 227              return false;
 228          }
 229  
 230          // Margin of error is the time it took the request to complete.
 231          $margin_of_error  = $timestamp_receive - $timestamp_send;
 232  
 233          // Guess the time gap between sending the request and the remote machine
 234          // executing the time() function. Marginally better than nothing.
 235          $hysteresis       = ($margin_of_error) / 2;
 236  
 237          $remote_timestamp = $sig_parser->remote_timestamp - $hysteresis;
 238          $time_offset      = $remote_timestamp - $timestamp_send;
 239          if ($time_offset > 0) {
 240              $threshold = get_config('mnet', 'drift_threshold');
 241              if(empty($threshold)) {
 242                  // We decided 15 seconds was a pretty good arbitrary threshold
 243                  // for time-drift between servers, but you can customize this in
 244                  // the config_plugins table. It's not advised though.
 245                  set_config('drift_threshold', 15, 'mnet');
 246                  $threshold = 15;
 247              }
 248              if ($time_offset > $threshold) {
 249                  $this->error[] = '6:Time gap with '.$mnet_peer->name.' ('.$time_offset.' seconds) is greater than the permitted maximum of '.$threshold.' seconds';
 250                  return false;
 251              }
 252          }
 253  
 254          $this->xmlrpcresponse = base64_decode($sig_parser->data_object);
 255          $this->response       = xmlrpc_decode($this->xmlrpcresponse);
 256  
 257          // xmlrpc errors are pushed onto the $this->error stack
 258          if (is_array($this->response) && array_key_exists('faultCode', $this->response)) {
 259              // The faultCode 7025 means we tried to connect with an old SSL key
 260              // The faultString is the new key - let's save it and try again
 261              // The re_key attribute stops us from getting into a loop
 262              if($this->response['faultCode'] == 7025 && empty($mnet_peer->re_key)) {
 263                  mnet_debug('recieved an old-key fault, so trying to get the new key and update our records');
 264                  // If the new certificate doesn't come thru clean_param() unmolested, error out
 265                  if($this->response['faultString'] != clean_param($this->response['faultString'], PARAM_PEM)) {
 266                      $this->error[] = $this->response['faultCode'] . " : " . $this->response['faultString'];
 267                  }
 268                  $record                     = new stdClass();
 269                  $record->id                 = $mnet_peer->id;
 270                  $record->public_key         = $this->response['faultString'];
 271                  $details                    = openssl_x509_parse($record->public_key);
 272                  if(!isset($details['validTo_time_t'])) {
 273                      $this->error[] = $this->response['faultCode'] . " : " . $this->response['faultString'];
 274                  }
 275                  $record->public_key_expires = $details['validTo_time_t'];
 276                  $DB->update_record('mnet_host', $record);
 277  
 278                  // Create a new peer object populated with the new info & try re-sending the request
 279                  $rekeyed_mnet_peer = new mnet_peer();
 280                  $rekeyed_mnet_peer->set_id($record->id);
 281                  $rekeyed_mnet_peer->re_key = true;
 282                  return $this->send($rekeyed_mnet_peer);
 283              }
 284              if (!empty($CFG->mnet_rpcdebug)) {
 285                  if (get_string_manager()->string_exists('error'.$this->response['faultCode'], 'mnet')) {
 286                      $guidance = get_string('error'.$this->response['faultCode'], 'mnet');
 287                  } else {
 288                      $guidance = '';
 289                  }
 290              } else {
 291                  $guidance = '';
 292              }
 293              $this->error[] = $this->response['faultCode'] . " : " . $this->response['faultString'] ."\n".$guidance;
 294          }
 295  
 296          // ok, it's signed, but is it signed with the right certificate ?
 297          // do this *after* we check for an out of date key
 298          $verified = openssl_verify($this->xmlrpcresponse, base64_decode($sig_parser->signature), $mnet_peer->public_key);
 299          if ($verified != 1) {
 300              $this->error[] = 'Invalid signature';
 301          }
 302  
 303          return empty($this->error);
 304      }
 305  
 306      /**
 307       * Check that we are permitted to call method on specified peer
 308       *
 309       * @param object $mnet_peer A mnet_peer object with details of the remote host we're connecting to
 310       * @return bool True if we permit calls to method on specified peer, False otherwise.
 311       */
 312  
 313      function permission_to_call($mnet_peer) {
 314          global $DB, $CFG, $USER;
 315  
 316          // Executing any system method is permitted.
 317          $system_methods = array('system/listMethods', 'system/methodSignature', 'system/methodHelp', 'system/listServices');
 318          if (in_array($this->method, $system_methods) ) {
 319              return true;
 320          }
 321  
 322          $hostids = array($mnet_peer->id);
 323          if (!empty($CFG->mnet_all_hosts_id)) {
 324              $hostids[] = $CFG->mnet_all_hosts_id;
 325          }
 326          // At this point, we don't care if the remote host implements the
 327          // method we're trying to call. We just want to know that:
 328          // 1. The method belongs to some service, as far as OUR host knows
 329          // 2. We are allowed to subscribe to that service on this mnet_peer
 330  
 331          list($hostidsql, $hostidparams) = $DB->get_in_or_equal($hostids);
 332  
 333          $sql = "SELECT r.id
 334                    FROM {mnet_remote_rpc} r
 335              INNER JOIN {mnet_remote_service2rpc} s2r ON s2r.rpcid = r.id
 336              INNER JOIN {mnet_host2service} h2s ON h2s.serviceid = s2r.serviceid
 337                   WHERE r.xmlrpcpath = ?
 338                         AND h2s.subscribe = ?
 339                         AND h2s.hostid $hostidsql";
 340  
 341          $params = array($this->method, 1);
 342          $params = array_merge($params, $hostidparams);
 343  
 344          if ($DB->record_exists_sql($sql, $params)) {
 345              return true;
 346          }
 347  
 348          $this->error[] = '7:User with ID '. $USER->id .
 349                           ' attempted to call unauthorised method '.
 350                           $this->method.' on host '.
 351                           $mnet_peer->wwwroot;
 352          return false;
 353      }
 354  
 355      /**
 356       * Generate a curl handle and prepare it for sending to an mnet host
 357       *
 358       * @param object $mnet_peer A mnet_peer object with details of the remote host the request will be sent to
 359       * @return cURL handle - the almost-ready-to-send http request
 360       */
 361      function prepare_http_request ($mnet_peer) {
 362          $this->uri = $mnet_peer->wwwroot . $mnet_peer->application->xmlrpc_server_url;
 363  
 364          // Initialize request the target URL
 365          $httprequest = curl_init($this->uri);
 366          curl_setopt($httprequest, CURLOPT_TIMEOUT, $this->timeout);
 367          curl_setopt($httprequest, CURLOPT_RETURNTRANSFER, true);
 368          curl_setopt($httprequest, CURLOPT_POST, true);
 369          curl_setopt($httprequest, CURLOPT_USERAGENT, 'Moodle');
 370          curl_setopt($httprequest, CURLOPT_HTTPHEADER, array("Content-Type: text/xml charset=UTF-8"));
 371          curl_setopt($httprequest, CURLOPT_SSL_VERIFYPEER, false);
 372          curl_setopt($httprequest, CURLOPT_SSL_VERIFYHOST, 0);
 373          return $httprequest;
 374      }
 375  }