mod/dfrn_poll.php

   1 <?php
   2
   3 /**
   4  * @file mod/dfrn_poll.php
   5  */
   6
   7 use Friendica\App;
   8 use Friendica\Core\Config;
   9 use Friendica\Core\Logger;
  10 use Friendica\Core\System;
  11 use Friendica\Core\Session;
  12 use Friendica\Database\DBA;
  13 use Friendica\DI;
  14 use Friendica\Protocol\DFRN;
  15 use Friendica\Protocol\OStatus;
  16 use Friendica\Util\Network;
  17 use Friendica\Util\Strings;
  18 use Friendica\Util\XML;
  19
  20 function dfrn_poll_init(App $a)
  21 {
  22         DI::auth()->withSession($a);
  23
  24         $dfrn_id         =  $_GET['dfrn_id']         ?? '';
  25         $type            = ($_GET['type']            ?? '') ?: 'data';
  26         $last_update     =  $_GET['last_update']     ?? '';
  27         $destination_url =  $_GET['destination_url'] ?? '';
  28         $challenge       =  $_GET['challenge']       ?? '';
  29         $sec             =  $_GET['sec']             ?? '';
  30         $dfrn_version    = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
  31         $quiet                   = !empty($_GET['quiet']);
  32
  33         // Possibly it is an OStatus compatible server that requests a user feed
  34         $user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
  35         if (($a->argc > 1) && ($dfrn_id == '') && !strstr($user_agent, 'Friendica')) {
  36                 $nickname = $a->argv[1];
  37                 header("Content-type: application/atom+xml");
  38                 echo OStatus::feed($nickname, $last_update, 10);
  39                 exit();
  40         }
  41
  42         $direction = -1;
  43
  44         if (strpos($dfrn_id, ':') == 1) {
  45                 $direction = intval(substr($dfrn_id, 0, 1));
  46                 $dfrn_id = substr($dfrn_id, 2);
  47         }
  48
  49         $hidewall = false;
  50
  51         if (($dfrn_id === '') && empty($_POST['dfrn_id'])) {
  52                 if (DI::config()->get('system', 'block_public') && !Session::isAuthenticated()) {
  53                         throw new \Friendica\Network\HTTPException\ForbiddenException();
  54                 }
  55
  56                 $user = '';
  57                 if ($a->argc > 1) {
  58                         $r = q("SELECT `hidewall`,`nickname` FROM `user` WHERE `user`.`nickname` = '%s' LIMIT 1",
  59                                 DBA::escape($a->argv[1])
  60                         );
  61                         if (!$r) {
  62                                 throw new \Friendica\Network\HTTPException\NotFoundException();
  63                         }
  64
  65                         $hidewall = ($r[0]['hidewall'] && !local_user());
  66
  67                         $user = $r[0]['nickname'];
  68                 }
  69
  70                 Logger::log('dfrn_poll: public feed request from ' . $_SERVER['REMOTE_ADDR'] . ' for ' . $user);
  71                 header("Content-type: application/atom+xml");
  72                 echo DFRN::feed('', $user, $last_update, 0, $hidewall);
  73                 exit();
  74         }
  75
  76         if (($type === 'profile') && (!strlen($sec))) {
  77                 $sql_extra = '';
  78                 switch ($direction) {
  79                         case -1:
  80                                 $sql_extra = sprintf(" AND ( `dfrn-id` = '%s' OR `issued-id` = '%s' ) ", DBA::escape($dfrn_id), DBA::escape($dfrn_id));
  81                                 $my_id = $dfrn_id;
  82                                 break;
  83                         case 0:
  84                                 $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
  85                                 $my_id = '1:' . $dfrn_id;
  86                                 break;
  87                         case 1:
  88                                 $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
  89                                 $my_id = '0:' . $dfrn_id;
  90                                 break;
  91                         default:
  92                                 DI::baseUrl()->redirect();
  93                                 break; // NOTREACHED
  94                 }
  95
  96                 $r = q("SELECT `contact`.*, `user`.`username`, `user`.`nickname`
  97                         FROM `contact` LEFT JOIN `user` ON `contact`.`uid` = `user`.`uid`
  98                         WHERE `contact`.`blocked` = 0 AND `contact`.`pending` = 0
  99                         AND `user`.`nickname` = '%s' $sql_extra LIMIT 1",
 100                         DBA::escape($a->argv[1])
 101                 );
 102
 103                 if (DBA::isResult($r)) {
 104                         $s = Network::fetchUrl($r[0]['poll'] . '?dfrn_id=' . $my_id . '&type=profile-check');
 105
 106                         Logger::log("dfrn_poll: old profile returns " . $s, Logger::DATA);
 107
 108                         if (strlen($s)) {
 109                                 $xml = XML::parseString($s);
 110
 111                                 if ((int)$xml->status === 1) {
 112                                         $_SESSION['authenticated'] = 1;
 113                                         $_SESSION['visitor_id'] = $r[0]['id'];
 114                                         $_SESSION['visitor_home'] = $r[0]['url'];
 115                                         $_SESSION['visitor_handle'] = $r[0]['addr'];
 116                                         $_SESSION['visitor_visiting'] = $r[0]['uid'];
 117                                         $_SESSION['my_url'] = $r[0]['url'];
 118
 119                                         Session::setVisitorsContacts();
 120
 121                                         if (!$quiet) {
 122                                                 info(DI::l10n()->t('%1$s welcomes %2$s', $r[0]['username'], $r[0]['name']) . EOL);
 123                                         }
 124
 125                                         // Visitors get 1 day session.
 126                                         $session_id = session_id();
 127                                         $expire = time() + 86400;
 128                                         q("UPDATE `session` SET `expire` = '%s' WHERE `sid` = '%s'",
 129                                                 DBA::escape($expire),
 130                                                 DBA::escape($session_id)
 131                                         );
 132                                 }
 133                         }
 134
 135                         $profile = (count($r) > 0 && isset($r[0]['nickname']) ? $r[0]['nickname'] : '');
 136                         if (!empty($destination_url)) {
 137                                 System::externalRedirect($destination_url);
 138                         } else {
 139                                 DI::baseUrl()->redirect('profile/' . $profile);
 140                         }
 141                 }
 142                 DI::baseUrl()->redirect();
 143         }
 144
 145         if ($type === 'profile-check' && $dfrn_version < 2.2) {
 146                 if ((strlen($challenge)) && (strlen($sec))) {
 147                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 148                         $r = q("SELECT * FROM `profile_check` WHERE `sec` = '%s' ORDER BY `expire` DESC LIMIT 1",
 149                                 DBA::escape($sec)
 150                         );
 151                         if (!DBA::isResult($r)) {
 152                                 System::xmlExit(3, 'No ticket');
 153                                 // NOTREACHED
 154                         }
 155
 156                         $orig_id = $r[0]['dfrn_id'];
 157                         if (strpos($orig_id, ':')) {
 158                                 $orig_id = substr($orig_id, 2);
 159                         }
 160
 161                         $c = q("SELECT * FROM `contact` WHERE `id` = %d LIMIT 1",
 162                                 intval($r[0]['cid'])
 163                         );
 164                         if (!DBA::isResult($c)) {
 165                                 System::xmlExit(3, 'No profile');
 166                         }
 167
 168                         $contact = $c[0];
 169
 170                         $sent_dfrn_id = hex2bin($dfrn_id);
 171                         $challenge = hex2bin($challenge);
 172
 173                         $final_dfrn_id = '';
 174
 175                         if (($contact['duplex']) && strlen($contact['prvkey'])) {
 176                                 openssl_private_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['prvkey']);
 177                                 openssl_private_decrypt($challenge, $decoded_challenge, $contact['prvkey']);
 178                         } else {
 179                                 openssl_public_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['pubkey']);
 180                                 openssl_public_decrypt($challenge, $decoded_challenge, $contact['pubkey']);
 181                         }
 182
 183                         $final_dfrn_id = substr($final_dfrn_id, 0, strpos($final_dfrn_id, '.'));
 184
 185                         if (strpos($final_dfrn_id, ':') == 1) {
 186                                 $final_dfrn_id = substr($final_dfrn_id, 2);
 187                         }
 188
 189                         if ($final_dfrn_id != $orig_id) {
 190                                 Logger::log('profile_check: ' . $final_dfrn_id . ' != ' . $orig_id, Logger::DEBUG);
 191                                 // did not decode properly - cannot trust this site
 192                                 System::xmlExit(3, 'Bad decryption');
 193                         }
 194
 195                         header("Content-type: text/xml");
 196                         echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?><dfrn_poll><status>0</status><challenge>$decoded_challenge</challenge><sec>$sec</sec></dfrn_poll>";
 197                         exit();
 198                         // NOTREACHED
 199                 } else {
 200                         // old protocol
 201                         switch ($direction) {
 202                                 case 1:
 203                                         $dfrn_id = '0:' . $dfrn_id;
 204                                         break;
 205                                 case 0:
 206                                         $dfrn_id = '1:' . $dfrn_id;
 207                                         break;
 208                                 default:
 209                                         break;
 210                         }
 211
 212                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 213                         $r = q("SELECT * FROM `profile_check` WHERE `dfrn_id` = '%s' ORDER BY `expire` DESC",
 214                                 DBA::escape($dfrn_id));
 215                         if (DBA::isResult($r)) {
 216                                 System::xmlExit(1);
 217                                 return; // NOTREACHED
 218                         }
 219                         System::xmlExit(0);
 220                         return; // NOTREACHED
 221                 }
 222         }
 223 }
 224
 225 function dfrn_poll_post(App $a)
 226 {
 227         $dfrn_id      =  $_POST['dfrn_id']   ?? '';
 228         $challenge    =  $_POST['challenge'] ?? '';
 229         $url          =  $_POST['url']       ?? '';
 230         $sec          =  $_POST['sec']       ?? '';
 231         $ptype        =  $_POST['type']      ?? '';
 232         $perm         = ($_POST['perm']      ?? '') ?: 'r';
 233         $dfrn_version = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
 234
 235         if ($ptype === 'profile-check') {
 236                 if (strlen($challenge) && strlen($sec)) {
 237                         Logger::log('dfrn_poll: POST: profile-check');
 238
 239                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 240                         $r = q("SELECT * FROM `profile_check` WHERE `sec` = '%s' ORDER BY `expire` DESC LIMIT 1",
 241                                 DBA::escape($sec)
 242                         );
 243                         if (!DBA::isResult($r)) {
 244                                 System::xmlExit(3, 'No ticket');
 245                                 // NOTREACHED
 246                         }
 247
 248                         $orig_id = $r[0]['dfrn_id'];
 249                         if (strpos($orig_id, ':')) {
 250                                 $orig_id = substr($orig_id, 2);
 251                         }
 252
 253                         $c = q("SELECT * FROM `contact` WHERE `id` = %d LIMIT 1",
 254                                 intval($r[0]['cid'])
 255                         );
 256                         if (!DBA::isResult($c)) {
 257                                 System::xmlExit(3, 'No profile');
 258                         }
 259
 260                         $contact = $c[0];
 261
 262                         $sent_dfrn_id = hex2bin($dfrn_id);
 263                         $challenge = hex2bin($challenge);
 264
 265                         $final_dfrn_id = '';
 266
 267                         if ($contact['duplex'] && strlen($contact['prvkey'])) {
 268                                 openssl_private_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['prvkey']);
 269                                 openssl_private_decrypt($challenge, $decoded_challenge, $contact['prvkey']);
 270                         } else {
 271                                 openssl_public_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['pubkey']);
 272                                 openssl_public_decrypt($challenge, $decoded_challenge, $contact['pubkey']);
 273                         }
 274
 275                         $final_dfrn_id = substr($final_dfrn_id, 0, strpos($final_dfrn_id, '.'));
 276
 277                         if (strpos($final_dfrn_id, ':') == 1) {
 278                                 $final_dfrn_id = substr($final_dfrn_id, 2);
 279                         }
 280
 281                         if ($final_dfrn_id != $orig_id) {
 282                                 Logger::log('profile_check: ' . $final_dfrn_id . ' != ' . $orig_id, Logger::DEBUG);
 283                                 // did not decode properly - cannot trust this site
 284                                 System::xmlExit(3, 'Bad decryption');
 285                         }
 286
 287                         header("Content-type: text/xml");
 288                         echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?><dfrn_poll><status>0</status><challenge>$decoded_challenge</challenge><sec>$sec</sec></dfrn_poll>";
 289                         exit();
 290                         // NOTREACHED
 291                 }
 292         }
 293
 294         $direction = -1;
 295         if (strpos($dfrn_id, ':') == 1) {
 296                 $direction = intval(substr($dfrn_id, 0, 1));
 297                 $dfrn_id = substr($dfrn_id, 2);
 298         }
 299
 300         $r = q("SELECT * FROM `challenge` WHERE `dfrn-id` = '%s' AND `challenge` = '%s' LIMIT 1",
 301                 DBA::escape($dfrn_id),
 302                 DBA::escape($challenge)
 303         );
 304
 305         if (!DBA::isResult($r)) {
 306                 exit();
 307         }
 308
 309         $type = $r[0]['type'];
 310         $last_update = $r[0]['last_update'];
 311
 312         DBA::delete('challenge', ['dfrn-id' => $dfrn_id, 'challenge' => $challenge]);
 313
 314         $sql_extra = '';
 315         switch ($direction) {
 316                 case -1:
 317                         $sql_extra = sprintf(" AND `issued-id` = '%s' ", DBA::escape($dfrn_id));
 318                         break;
 319                 case 0:
 320                         $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 321                         break;
 322                 case 1:
 323                         $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 324                         break;
 325                 default:
 326                         DI::baseUrl()->redirect();
 327                         break; // NOTREACHED
 328         }
 329
 330         $r = q("SELECT * FROM `contact` WHERE `blocked` = 0 AND `pending` = 0 $sql_extra LIMIT 1");
 331         if (!DBA::isResult($r)) {
 332                 exit();
 333         }
 334
 335         $contact = $r[0];
 336         $owner_uid = $r[0]['uid'];
 337         $contact_id = $r[0]['id'];
 338
 339         if ($type === 'reputation' && strlen($url)) {
 340                 $r = q("SELECT * FROM `contact` WHERE `url` = '%s' AND `uid` = %d LIMIT 1",
 341                         DBA::escape($url),
 342                         intval($owner_uid)
 343                 );
 344                 $reputation = 0;
 345                 $text = '';
 346
 347                 if (DBA::isResult($r)) {
 348                         $reputation = $r[0]['rating'];
 349                         $text = $r[0]['reason'];
 350
 351                         if ($r[0]['id'] == $contact_id) { // inquiring about own reputation not allowed
 352                                 $reputation = 0;
 353                                 $text = '';
 354                         }
 355                 }
 356
 357                 echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?>
 358                 <reputation>
 359                         <url>$url</url>
 360                         <rating>$reputation</rating>
 361                         <description>$text</description>
 362                 </reputation>
 363                 ";
 364                 exit();
 365                 // NOTREACHED
 366         } else {
 367                 // Update the writable flag if it changed
 368                 Logger::log('dfrn_poll: post request feed: ' . print_r($_POST, true), Logger::DATA);
 369                 if ($dfrn_version >= 2.21) {
 370                         if ($perm === 'rw') {
 371                                 $writable = 1;
 372                         } else {
 373                                 $writable = 0;
 374                         }
 375
 376                         if ($writable != $contact['writable']) {
 377                                 q("UPDATE `contact` SET `writable` = %d WHERE `id` = %d",
 378                                         intval($writable),
 379                                         intval($contact_id)
 380                                 );
 381                         }
 382                 }
 383
 384                 header("Content-type: application/atom+xml");
 385                 $o = DFRN::feed($dfrn_id, $a->argv[1], $last_update, $direction);
 386                 echo $o;
 387                 exit();
 388         }
 389 }
 390
 391 function dfrn_poll_content(App $a)
 392 {
 393         $dfrn_id         =  $_GET['dfrn_id']         ?? '';
 394         $type            = ($_GET['type']            ?? '') ?: 'data';
 395         $last_update     =  $_GET['last_update']     ?? '';
 396         $destination_url =  $_GET['destination_url'] ?? '';
 397         $sec             =  $_GET['sec']             ?? '';
 398         $dfrn_version    = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
 399         $quiet           = !empty($_GET['quiet']);
 400
 401         $direction = -1;
 402         if (strpos($dfrn_id, ':') == 1) {
 403                 $direction = intval(substr($dfrn_id, 0, 1));
 404                 $dfrn_id = substr($dfrn_id, 2);
 405         }
 406
 407         if ($dfrn_id != '') {
 408                 // initial communication from external contact
 409                 $hash = Strings::getRandomHex();
 410
 411                 $status = 0;
 412
 413                 DBA::delete('challenge', ["`expire` < ?", time()]);
 414
 415                 if ($type !== 'profile') {
 416                         q("INSERT INTO `challenge` ( `challenge`, `dfrn-id`, `expire` , `type`, `last_update` )
 417                                 VALUES( '%s', '%s', '%s', '%s', '%s' ) ",
 418                                 DBA::escape($hash),
 419                                 DBA::escape($dfrn_id),
 420                                 intval(time() + 60 ),
 421                                 DBA::escape($type),
 422                                 DBA::escape($last_update)
 423                         );
 424                 }
 425
 426                 $sql_extra = '';
 427                 switch ($direction) {
 428                         case -1:
 429                                 if ($type === 'profile') {
 430                                         $sql_extra = sprintf(" AND (`dfrn-id` = '%s' OR `issued-id` = '%s') ", DBA::escape($dfrn_id), DBA::escape($dfrn_id));
 431                                 } else {
 432                                         $sql_extra = sprintf(" AND `issued-id` = '%s' ", DBA::escape($dfrn_id));
 433                                 }
 434
 435                                 $my_id = $dfrn_id;
 436                                 break;
 437                         case 0:
 438                                 $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 439                                 $my_id = '1:' . $dfrn_id;
 440                                 break;
 441                         case 1:
 442                                 $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 443                                 $my_id = '0:' . $dfrn_id;
 444                                 break;
 445                         default:
 446                                 DI::baseUrl()->redirect();
 447                                 break; // NOTREACHED
 448                 }
 449
 450                 $nickname = $a->argv[1];
 451
 452                 $r = q("SELECT `contact`.*, `user`.`username`, `user`.`nickname`
 453                         FROM `contact` LEFT JOIN `user` ON `contact`.`uid` = `user`.`uid`
 454                         WHERE `contact`.`blocked` = 0 AND `contact`.`pending` = 0
 455                         AND `user`.`nickname` = '%s' $sql_extra LIMIT 1",
 456                         DBA::escape($nickname)
 457                 );
 458                 if (DBA::isResult($r)) {
 459                         $challenge = '';
 460                         $encrypted_id = '';
 461                         $id_str = $my_id . '.' . mt_rand(1000, 9999);
 462
 463                         if (($r[0]['duplex'] && strlen($r[0]['pubkey'])) || !strlen($r[0]['prvkey'])) {
 464                                 openssl_public_encrypt($hash, $challenge, $r[0]['pubkey']);
 465                                 openssl_public_encrypt($id_str, $encrypted_id, $r[0]['pubkey']);
 466                         } else {
 467                                 openssl_private_encrypt($hash, $challenge, $r[0]['prvkey']);
 468                                 openssl_private_encrypt($id_str, $encrypted_id, $r[0]['prvkey']);
 469                         }
 470
 471                         $challenge = bin2hex($challenge);
 472                         $encrypted_id = bin2hex($encrypted_id);
 473                 } else {
 474                         $status = 1;
 475                         $challenge = '';
 476                         $encrypted_id = '';
 477                 }
 478
 479                 if (($type === 'profile') && (strlen($sec))) {
 480                         // heluecht: I don't know why we don't fail immediately when the user or contact hadn't been found.
 481                         // Since it doesn't make sense to continue from this point on, we now fail here. This should be safe.
 482                         if (!DBA::isResult($r)) {
 483                                 throw new \Friendica\Network\HTTPException\NotFoundException();
 484                         }
 485
 486                         // URL reply
 487                         if ($dfrn_version < 2.2) {
 488                                 $s = Network::fetchUrl($r[0]['poll']
 489                                         . '?dfrn_id=' . $encrypted_id
 490                                         . '&type=profile-check'
 491                                         . '&dfrn_version=' . DFRN_PROTOCOL_VERSION
 492                                         . '&challenge=' . $challenge
 493                                         . '&sec=' . $sec
 494                                 );
 495                         } else {
 496                                 $s = Network::post($r[0]['poll'], [
 497                                         'dfrn_id' => $encrypted_id,
 498                                         'type' => 'profile-check',
 499                                         'dfrn_version' => DFRN_PROTOCOL_VERSION,
 500                                         'challenge' => $challenge,
 501                                         'sec' => $sec
 502                                 ])->getBody();
 503                         }
 504
 505                         Logger::log("dfrn_poll: sec profile: " . $s, Logger::DATA);
 506
 507                         if (strlen($s) && strstr($s, '<?xml')) {
 508                                 $xml = XML::parseString($s);
 509
 510                                 Logger::log('dfrn_poll: profile: parsed xml: ' . print_r($xml, true), Logger::DATA);
 511
 512                                 Logger::log('dfrn_poll: secure profile: challenge: ' . $xml->challenge . ' expecting ' . $hash);
 513                                 Logger::log('dfrn_poll: secure profile: sec: ' . $xml->sec . ' expecting ' . $sec);
 514
 515                                 if (((int) $xml->status == 0) && ($xml->challenge == $hash) && ($xml->sec == $sec)) {
 516                                         $_SESSION['authenticated'] = 1;
 517                                         $_SESSION['visitor_id'] = $r[0]['id'];
 518                                         $_SESSION['visitor_home'] = $r[0]['url'];
 519                                         $_SESSION['visitor_visiting'] = $r[0]['uid'];
 520                                         $_SESSION['my_url'] = $r[0]['url'];
 521
 522                                         Session::setVisitorsContacts();
 523
 524                                         if (!$quiet) {
 525                                                 info(DI::l10n()->t('%1$s welcomes %2$s', $r[0]['username'], $r[0]['name']) . EOL);
 526                                         }
 527
 528                                         // Visitors get 1 day session.
 529                                         $session_id = session_id();
 530                                         $expire = time() + 86400;
 531                                         q("UPDATE `session` SET `expire` = '%s' WHERE `sid` = '%s'",
 532                                                 DBA::escape($expire),
 533                                                 DBA::escape($session_id)
 534                                         );
 535                                 }
 536                         }
 537
 538                         $profile = ((DBA::isResult($r) && $r[0]['nickname']) ? $r[0]['nickname'] : $nickname);
 539
 540                         switch ($destination_url) {
 541                                 case 'profile':
 542                                         DI::baseUrl()->redirect('profile/' . $profile . '?tab=profile');
 543                                         break;
 544                                 case 'photos':
 545                                         DI::baseUrl()->redirect('photos/' . $profile);
 546                                         break;
 547                                 case 'status':
 548                                 case '':
 549                                         DI::baseUrl()->redirect('profile/' . $profile);
 550                                         break;
 551                                 default:
 552                                         $appendix = (strstr($destination_url, '?') ? '&redir=1' : '?redir=1');
 553                                         DI::baseUrl()->redirect($destination_url . $appendix);
 554                                         break;
 555                         }
 556                         // NOTREACHED
 557                 } else {
 558                         // XML reply
 559                         header("Content-type: text/xml");
 560                         echo '<?xml version="1.0" encoding="UTF-8"?>' . "\r\n"
 561                                 . '<dfrn_poll>' . "\r\n"
 562                                 . "\t" . '<status>' . $status . '</status>' . "\r\n"
 563                                 . "\t" . '<dfrn_version>' . DFRN_PROTOCOL_VERSION . '</dfrn_version>' . "\r\n"
 564                                 . "\t" . '<dfrn_id>' . $encrypted_id . '</dfrn_id>' . "\r\n"
 565                                 . "\t" . '<challenge>' . $challenge . '</challenge>' . "\r\n"
 566                                 . '</dfrn_poll>' . "\r\n";
 567                         exit();
 568                         // NOTREACHED
 569                 }
 570         }
 571 }