mod/dfrn_poll.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2020, Friendica
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 use Friendica\App;
  23 use Friendica\Core\Logger;
  24 use Friendica\Core\Session;
  25 use Friendica\Core\System;
  26 use Friendica\Database\DBA;
  27 use Friendica\DI;
  28 use Friendica\Protocol\DFRN;
  29 use Friendica\Protocol\OStatus;
  30 use Friendica\Util\Strings;
  31 use Friendica\Util\XML;
  32
  33 function dfrn_poll_init(App $a)
  34 {
  35         DI::auth()->withSession($a);
  36
  37         $dfrn_id         =  $_GET['dfrn_id']         ?? '';
  38         $type            = ($_GET['type']            ?? '') ?: 'data';
  39         $last_update     =  $_GET['last_update']     ?? '';
  40         $destination_url =  $_GET['destination_url'] ?? '';
  41         $challenge       =  $_GET['challenge']       ?? '';
  42         $sec             =  $_GET['sec']             ?? '';
  43         $dfrn_version    = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
  44         $quiet                   = !empty($_GET['quiet']);
  45
  46         // Possibly it is an OStatus compatible server that requests a user feed
  47         $user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
  48         if (($a->argc > 1) && ($dfrn_id == '') && !strstr($user_agent, 'Friendica')) {
  49                 $nickname = $a->argv[1];
  50                 header("Content-type: application/atom+xml");
  51                 echo OStatus::feed($nickname, $last_update, 10);
  52                 exit();
  53         }
  54
  55         $direction = -1;
  56
  57         if (strpos($dfrn_id, ':') == 1) {
  58                 $direction = intval(substr($dfrn_id, 0, 1));
  59                 $dfrn_id = substr($dfrn_id, 2);
  60         }
  61
  62         $hidewall = false;
  63
  64         if (($dfrn_id === '') && empty($_POST['dfrn_id'])) {
  65                 if (DI::config()->get('system', 'block_public') && !Session::isAuthenticated()) {
  66                         throw new \Friendica\Network\HTTPException\ForbiddenException();
  67                 }
  68
  69                 $user = '';
  70                 if ($a->argc > 1) {
  71                         $r = q("SELECT `hidewall`,`nickname` FROM `user` WHERE `user`.`nickname` = '%s' LIMIT 1",
  72                                 DBA::escape($a->argv[1])
  73                         );
  74                         if (!$r) {
  75                                 throw new \Friendica\Network\HTTPException\NotFoundException();
  76                         }
  77
  78                         $hidewall = ($r[0]['hidewall'] && !local_user());
  79
  80                         $user = $r[0]['nickname'];
  81                 }
  82
  83                 Logger::log('dfrn_poll: public feed request from ' . $_SERVER['REMOTE_ADDR'] . ' for ' . $user);
  84                 header("Content-type: application/atom+xml");
  85                 echo DFRN::feed('', $user, $last_update, 0, $hidewall);
  86                 exit();
  87         }
  88
  89         if (($type === 'profile') && (!strlen($sec))) {
  90                 $sql_extra = '';
  91                 switch ($direction) {
  92                         case -1:
  93                                 $sql_extra = sprintf(" AND ( `dfrn-id` = '%s' OR `issued-id` = '%s' ) ", DBA::escape($dfrn_id), DBA::escape($dfrn_id));
  94                                 $my_id = $dfrn_id;
  95                                 break;
  96                         case 0:
  97                                 $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
  98                                 $my_id = '1:' . $dfrn_id;
  99                                 break;
 100                         case 1:
 101                                 $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 102                                 $my_id = '0:' . $dfrn_id;
 103                                 break;
 104                         default:
 105                                 DI::baseUrl()->redirect();
 106                                 break; // NOTREACHED
 107                 }
 108
 109                 $r = q("SELECT `contact`.*, `user`.`username`, `user`.`nickname`
 110                         FROM `contact` LEFT JOIN `user` ON `contact`.`uid` = `user`.`uid`
 111                         WHERE `contact`.`blocked` = 0 AND `contact`.`pending` = 0
 112                         AND `user`.`nickname` = '%s' $sql_extra LIMIT 1",
 113                         DBA::escape($a->argv[1])
 114                 );
 115
 116                 if (DBA::isResult($r)) {
 117                         $s = DI::httpRequest()->fetch($r[0]['poll'] . '?dfrn_id=' . $my_id . '&type=profile-check');
 118
 119                         Logger::log("dfrn_poll: old profile returns " . $s, Logger::DATA);
 120
 121                         if (strlen($s)) {
 122                                 $xml = XML::parseString($s);
 123
 124                                 if ((int)$xml->status === 1) {
 125                                         $_SESSION['authenticated'] = 1;
 126                                         $_SESSION['visitor_id'] = $r[0]['id'];
 127                                         $_SESSION['visitor_home'] = $r[0]['url'];
 128                                         $_SESSION['visitor_handle'] = $r[0]['addr'];
 129                                         $_SESSION['visitor_visiting'] = $r[0]['uid'];
 130                                         $_SESSION['my_url'] = $r[0]['url'];
 131
 132                                         Session::setVisitorsContacts();
 133
 134                                         if (!$quiet) {
 135                                                 info(DI::l10n()->t('%1$s welcomes %2$s', $r[0]['username'], $r[0]['name']));
 136                                         }
 137
 138                                         // Visitors get 1 day session.
 139                                         $session_id = session_id();
 140                                         $expire = time() + 86400;
 141                                         q("UPDATE `session` SET `expire` = '%s' WHERE `sid` = '%s'",
 142                                                 DBA::escape($expire),
 143                                                 DBA::escape($session_id)
 144                                         );
 145                                 }
 146                         }
 147
 148                         $profile = (count($r) > 0 && isset($r[0]['nickname']) ? $r[0]['nickname'] : '');
 149                         if (!empty($destination_url)) {
 150                                 System::externalRedirect($destination_url);
 151                         } else {
 152                                 DI::baseUrl()->redirect('profile/' . $profile);
 153                         }
 154                 }
 155                 DI::baseUrl()->redirect();
 156         }
 157
 158         if ($type === 'profile-check' && $dfrn_version < 2.2) {
 159                 if ((strlen($challenge)) && (strlen($sec))) {
 160                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 161                         $r = q("SELECT * FROM `profile_check` WHERE `sec` = '%s' ORDER BY `expire` DESC LIMIT 1",
 162                                 DBA::escape($sec)
 163                         );
 164                         if (!DBA::isResult($r)) {
 165                                 System::xmlExit(3, 'No ticket');
 166                                 // NOTREACHED
 167                         }
 168
 169                         $orig_id = $r[0]['dfrn_id'];
 170                         if (strpos($orig_id, ':')) {
 171                                 $orig_id = substr($orig_id, 2);
 172                         }
 173
 174                         $c = q("SELECT * FROM `contact` WHERE `id` = %d LIMIT 1",
 175                                 intval($r[0]['cid'])
 176                         );
 177                         if (!DBA::isResult($c)) {
 178                                 System::xmlExit(3, 'No profile');
 179                         }
 180
 181                         $contact = $c[0];
 182
 183                         $sent_dfrn_id = hex2bin($dfrn_id);
 184                         $challenge = hex2bin($challenge);
 185
 186                         $final_dfrn_id = '';
 187
 188                         if (($contact['duplex']) && strlen($contact['prvkey'])) {
 189                                 openssl_private_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['prvkey']);
 190                                 openssl_private_decrypt($challenge, $decoded_challenge, $contact['prvkey']);
 191                         } else {
 192                                 openssl_public_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['pubkey']);
 193                                 openssl_public_decrypt($challenge, $decoded_challenge, $contact['pubkey']);
 194                         }
 195
 196                         $final_dfrn_id = substr($final_dfrn_id, 0, strpos($final_dfrn_id, '.'));
 197
 198                         if (strpos($final_dfrn_id, ':') == 1) {
 199                                 $final_dfrn_id = substr($final_dfrn_id, 2);
 200                         }
 201
 202                         if ($final_dfrn_id != $orig_id) {
 203                                 Logger::log('profile_check: ' . $final_dfrn_id . ' != ' . $orig_id, Logger::DEBUG);
 204                                 // did not decode properly - cannot trust this site
 205                                 System::xmlExit(3, 'Bad decryption');
 206                         }
 207
 208                         header("Content-type: text/xml");
 209                         echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?><dfrn_poll><status>0</status><challenge>$decoded_challenge</challenge><sec>$sec</sec></dfrn_poll>";
 210                         exit();
 211                         // NOTREACHED
 212                 } else {
 213                         // old protocol
 214                         switch ($direction) {
 215                                 case 1:
 216                                         $dfrn_id = '0:' . $dfrn_id;
 217                                         break;
 218                                 case 0:
 219                                         $dfrn_id = '1:' . $dfrn_id;
 220                                         break;
 221                                 default:
 222                                         break;
 223                         }
 224
 225                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 226                         $r = q("SELECT * FROM `profile_check` WHERE `dfrn_id` = '%s' ORDER BY `expire` DESC",
 227                                 DBA::escape($dfrn_id));
 228                         if (DBA::isResult($r)) {
 229                                 System::xmlExit(1);
 230                                 return; // NOTREACHED
 231                         }
 232                         System::xmlExit(0);
 233                         return; // NOTREACHED
 234                 }
 235         }
 236 }
 237
 238 function dfrn_poll_post(App $a)
 239 {
 240         $dfrn_id      =  $_POST['dfrn_id']   ?? '';
 241         $challenge    =  $_POST['challenge'] ?? '';
 242         $sec          =  $_POST['sec']       ?? '';
 243         $ptype        =  $_POST['type']      ?? '';
 244         $perm         = ($_POST['perm']      ?? '') ?: 'r';
 245         $dfrn_version = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
 246
 247         if ($ptype === 'profile-check') {
 248                 if (strlen($challenge) && strlen($sec)) {
 249                         Logger::log('dfrn_poll: POST: profile-check');
 250
 251                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 252                         $r = q("SELECT * FROM `profile_check` WHERE `sec` = '%s' ORDER BY `expire` DESC LIMIT 1",
 253                                 DBA::escape($sec)
 254                         );
 255                         if (!DBA::isResult($r)) {
 256                                 System::xmlExit(3, 'No ticket');
 257                                 // NOTREACHED
 258                         }
 259
 260                         $orig_id = $r[0]['dfrn_id'];
 261                         if (strpos($orig_id, ':')) {
 262                                 $orig_id = substr($orig_id, 2);
 263                         }
 264
 265                         $c = q("SELECT * FROM `contact` WHERE `id` = %d LIMIT 1",
 266                                 intval($r[0]['cid'])
 267                         );
 268                         if (!DBA::isResult($c)) {
 269                                 System::xmlExit(3, 'No profile');
 270                         }
 271
 272                         $contact = $c[0];
 273
 274                         $sent_dfrn_id = hex2bin($dfrn_id);
 275                         $challenge = hex2bin($challenge);
 276
 277                         $final_dfrn_id = '';
 278
 279                         if ($contact['duplex'] && strlen($contact['prvkey'])) {
 280                                 openssl_private_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['prvkey']);
 281                                 openssl_private_decrypt($challenge, $decoded_challenge, $contact['prvkey']);
 282                         } else {
 283                                 openssl_public_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['pubkey']);
 284                                 openssl_public_decrypt($challenge, $decoded_challenge, $contact['pubkey']);
 285                         }
 286
 287                         $final_dfrn_id = substr($final_dfrn_id, 0, strpos($final_dfrn_id, '.'));
 288
 289                         if (strpos($final_dfrn_id, ':') == 1) {
 290                                 $final_dfrn_id = substr($final_dfrn_id, 2);
 291                         }
 292
 293                         if ($final_dfrn_id != $orig_id) {
 294                                 Logger::log('profile_check: ' . $final_dfrn_id . ' != ' . $orig_id, Logger::DEBUG);
 295                                 // did not decode properly - cannot trust this site
 296                                 System::xmlExit(3, 'Bad decryption');
 297                         }
 298
 299                         header("Content-type: text/xml");
 300                         echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?><dfrn_poll><status>0</status><challenge>$decoded_challenge</challenge><sec>$sec</sec></dfrn_poll>";
 301                         exit();
 302                         // NOTREACHED
 303                 }
 304         }
 305
 306         $direction = -1;
 307         if (strpos($dfrn_id, ':') == 1) {
 308                 $direction = intval(substr($dfrn_id, 0, 1));
 309                 $dfrn_id = substr($dfrn_id, 2);
 310         }
 311
 312         $r = q("SELECT * FROM `challenge` WHERE `dfrn-id` = '%s' AND `challenge` = '%s' LIMIT 1",
 313                 DBA::escape($dfrn_id),
 314                 DBA::escape($challenge)
 315         );
 316
 317         if (!DBA::isResult($r)) {
 318                 exit();
 319         }
 320
 321         $last_update = $r[0]['last_update'];
 322
 323         DBA::delete('challenge', ['dfrn-id' => $dfrn_id, 'challenge' => $challenge]);
 324
 325         $sql_extra = '';
 326         switch ($direction) {
 327                 case -1:
 328                         $sql_extra = sprintf(" AND `issued-id` = '%s' ", DBA::escape($dfrn_id));
 329                         break;
 330                 case 0:
 331                         $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 332                         break;
 333                 case 1:
 334                         $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 335                         break;
 336                 default:
 337                         DI::baseUrl()->redirect();
 338                         break; // NOTREACHED
 339         }
 340
 341         $r = q("SELECT * FROM `contact` WHERE `blocked` = 0 AND `pending` = 0 $sql_extra LIMIT 1");
 342         if (!DBA::isResult($r)) {
 343                 exit();
 344         }
 345
 346         $contact = $r[0];
 347         $contact_id = $r[0]['id'];
 348
 349         // Update the writable flag if it changed
 350         Logger::debug('post request feed', ['post' => $_POST]);
 351         if ($dfrn_version >= 2.21) {
 352                 if ($perm === 'rw') {
 353                         $writable = 1;
 354                 } else {
 355                         $writable = 0;
 356                 }
 357
 358                 if ($writable != $contact['writable']) {
 359                         q("UPDATE `contact` SET `writable` = %d WHERE `id` = %d",
 360                                 intval($writable),
 361                                 intval($contact_id)
 362                         );
 363                 }
 364         }
 365
 366         header("Content-type: application/atom+xml");
 367         $o = DFRN::feed($dfrn_id, $a->argv[1], $last_update, $direction);
 368         echo $o;
 369         exit();
 370 }
 371
 372 function dfrn_poll_content(App $a)
 373 {
 374         $dfrn_id         =  $_GET['dfrn_id']         ?? '';
 375         $type            = ($_GET['type']            ?? '') ?: 'data';
 376         $last_update     =  $_GET['last_update']     ?? '';
 377         $destination_url =  $_GET['destination_url'] ?? '';
 378         $sec             =  $_GET['sec']             ?? '';
 379         $dfrn_version    = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
 380         $quiet           = !empty($_GET['quiet']);
 381
 382         $direction = -1;
 383         if (strpos($dfrn_id, ':') == 1) {
 384                 $direction = intval(substr($dfrn_id, 0, 1));
 385                 $dfrn_id = substr($dfrn_id, 2);
 386         }
 387
 388         if ($dfrn_id != '') {
 389                 // initial communication from external contact
 390                 $hash = Strings::getRandomHex();
 391
 392                 $status = 0;
 393
 394                 DBA::delete('challenge', ["`expire` < ?", time()]);
 395
 396                 if ($type !== 'profile') {
 397                         q("INSERT INTO `challenge` ( `challenge`, `dfrn-id`, `expire` , `type`, `last_update` )
 398                                 VALUES( '%s', '%s', '%s', '%s', '%s' ) ",
 399                                 DBA::escape($hash),
 400                                 DBA::escape($dfrn_id),
 401                                 intval(time() + 60 ),
 402                                 DBA::escape($type),
 403                                 DBA::escape($last_update)
 404                         );
 405                 }
 406
 407                 $sql_extra = '';
 408                 switch ($direction) {
 409                         case -1:
 410                                 if ($type === 'profile') {
 411                                         $sql_extra = sprintf(" AND (`dfrn-id` = '%s' OR `issued-id` = '%s') ", DBA::escape($dfrn_id), DBA::escape($dfrn_id));
 412                                 } else {
 413                                         $sql_extra = sprintf(" AND `issued-id` = '%s' ", DBA::escape($dfrn_id));
 414                                 }
 415
 416                                 $my_id = $dfrn_id;
 417                                 break;
 418                         case 0:
 419                                 $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 420                                 $my_id = '1:' . $dfrn_id;
 421                                 break;
 422                         case 1:
 423                                 $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 424                                 $my_id = '0:' . $dfrn_id;
 425                                 break;
 426                         default:
 427                                 DI::baseUrl()->redirect();
 428                                 break; // NOTREACHED
 429                 }
 430
 431                 $nickname = $a->argv[1];
 432
 433                 $r = q("SELECT `contact`.*, `user`.`username`, `user`.`nickname`
 434                         FROM `contact` LEFT JOIN `user` ON `contact`.`uid` = `user`.`uid`
 435                         WHERE `contact`.`blocked` = 0 AND `contact`.`pending` = 0
 436                         AND `user`.`nickname` = '%s' $sql_extra LIMIT 1",
 437                         DBA::escape($nickname)
 438                 );
 439                 if (DBA::isResult($r)) {
 440                         $challenge = '';
 441                         $encrypted_id = '';
 442                         $id_str = $my_id . '.' . mt_rand(1000, 9999);
 443
 444                         if (($r[0]['duplex'] && strlen($r[0]['pubkey'])) || !strlen($r[0]['prvkey'])) {
 445                                 openssl_public_encrypt($hash, $challenge, $r[0]['pubkey']);
 446                                 openssl_public_encrypt($id_str, $encrypted_id, $r[0]['pubkey']);
 447                         } else {
 448                                 openssl_private_encrypt($hash, $challenge, $r[0]['prvkey']);
 449                                 openssl_private_encrypt($id_str, $encrypted_id, $r[0]['prvkey']);
 450                         }
 451
 452                         $challenge = bin2hex($challenge);
 453                         $encrypted_id = bin2hex($encrypted_id);
 454                 } else {
 455                         $status = 1;
 456                         $challenge = '';
 457                         $encrypted_id = '';
 458                 }
 459
 460                 if (($type === 'profile') && (strlen($sec))) {
 461                         // heluecht: I don't know why we don't fail immediately when the user or contact hadn't been found.
 462                         // Since it doesn't make sense to continue from this point on, we now fail here. This should be safe.
 463                         if (!DBA::isResult($r)) {
 464                                 throw new \Friendica\Network\HTTPException\NotFoundException();
 465                         }
 466
 467                         // URL reply
 468                         if ($dfrn_version < 2.2) {
 469                                 $s = DI::httpRequest()->fetch($r[0]['poll']
 470                                                               . '?dfrn_id=' . $encrypted_id
 471                                                               . '&type=profile-check'
 472                                                               . '&dfrn_version=' . DFRN_PROTOCOL_VERSION
 473                                                               . '&challenge=' . $challenge
 474                                                               . '&sec=' . $sec
 475                                 );
 476                         } else {
 477                                 $s = DI::httpRequest()->post($r[0]['poll'], [
 478                                         'dfrn_id'      => $encrypted_id,
 479                                         'type'         => 'profile-check',
 480                                         'dfrn_version' => DFRN_PROTOCOL_VERSION,
 481                                         'challenge'    => $challenge,
 482                                         'sec'          => $sec
 483                                 ])->getBody();
 484                         }
 485
 486                         Logger::log("dfrn_poll: sec profile: " . $s, Logger::DATA);
 487
 488                         if (strlen($s) && strstr($s, '<?xml')) {
 489                                 $xml = XML::parseString($s);
 490
 491                                 Logger::debug(' profile: parsed', ['xml' => $xml]);
 492
 493                                 Logger::log('dfrn_poll: secure profile: challenge: ' . $xml->challenge . ' expecting ' . $hash);
 494                                 Logger::log('dfrn_poll: secure profile: sec: ' . $xml->sec . ' expecting ' . $sec);
 495
 496                                 if (((int) $xml->status == 0) && ($xml->challenge == $hash) && ($xml->sec == $sec)) {
 497                                         $_SESSION['authenticated'] = 1;
 498                                         $_SESSION['visitor_id'] = $r[0]['id'];
 499                                         $_SESSION['visitor_home'] = $r[0]['url'];
 500                                         $_SESSION['visitor_visiting'] = $r[0]['uid'];
 501                                         $_SESSION['my_url'] = $r[0]['url'];
 502
 503                                         Session::setVisitorsContacts();
 504
 505                                         if (!$quiet) {
 506                                                 info(DI::l10n()->t('%1$s welcomes %2$s', $r[0]['username'], $r[0]['name']));
 507                                         }
 508
 509                                         // Visitors get 1 day session.
 510                                         $session_id = session_id();
 511                                         $expire = time() + 86400;
 512                                         q("UPDATE `session` SET `expire` = '%s' WHERE `sid` = '%s'",
 513                                                 DBA::escape($expire),
 514                                                 DBA::escape($session_id)
 515                                         );
 516                                 }
 517                         }
 518
 519                         $profile = ((DBA::isResult($r) && $r[0]['nickname']) ? $r[0]['nickname'] : $nickname);
 520
 521                         switch ($destination_url) {
 522                                 case 'profile':
 523                                         DI::baseUrl()->redirect('profile/' . $profile . '/profile');
 524                                         break;
 525                                 case 'photos':
 526                                         DI::baseUrl()->redirect('photos/' . $profile);
 527                                         break;
 528                                 case 'status':
 529                                 case '':
 530                                         DI::baseUrl()->redirect('profile/' . $profile);
 531                                         break;
 532                                 default:
 533                                         $appendix = (strstr($destination_url, '?') ? '&redir=1' : '?redir=1');
 534                                         DI::baseUrl()->redirect($destination_url . $appendix);
 535                                         break;
 536                         }
 537                         // NOTREACHED
 538                 } else {
 539                         // XML reply
 540                         header("Content-type: text/xml");
 541                         echo '<?xml version="1.0" encoding="UTF-8"?>' . "\r\n"
 542                                 . '<dfrn_poll>' . "\r\n"
 543                                 . "\t" . '<status>' . $status . '</status>' . "\r\n"
 544                                 . "\t" . '<dfrn_version>' . DFRN_PROTOCOL_VERSION . '</dfrn_version>' . "\r\n"
 545                                 . "\t" . '<dfrn_id>' . $encrypted_id . '</dfrn_id>' . "\r\n"
 546                                 . "\t" . '<challenge>' . $challenge . '</challenge>' . "\r\n"
 547                                 . '</dfrn_poll>' . "\r\n";
 548                         exit();
 549                         // NOTREACHED
 550                 }
 551         }
 552 }