mod/dfrn_poll.php

   1 <?php
   2
   3 /**
   4  * @file mod/dfrn_poll.php
   5  */
   6
   7 use Friendica\App;
   8 use Friendica\BaseObject;
   9 use Friendica\App\Authentication;
  10 use Friendica\Core\Config;
  11 use Friendica\Core\L10n;
  12 use Friendica\Core\Logger;
  13 use Friendica\Core\System;
  14 use Friendica\Core\Session;
  15 use Friendica\Database\DBA;
  16 use Friendica\Module\Login;
  17 use Friendica\Protocol\DFRN;
  18 use Friendica\Protocol\OStatus;
  19 use Friendica\Util\Network;
  20 use Friendica\Util\Strings;
  21 use Friendica\Util\XML;
  22
  23 function dfrn_poll_init(App $a)
  24 {
  25         /** @var Authentication $authentication */
  26         $authentication = BaseObject::getClass(Authentication::class);
  27         $authentication->withSession($a);
  28
  29         $dfrn_id         =  $_GET['dfrn_id']         ?? '';
  30         $type            = ($_GET['type']            ?? '') ?: 'data';
  31         $last_update     =  $_GET['last_update']     ?? '';
  32         $destination_url =  $_GET['destination_url'] ?? '';
  33         $challenge       =  $_GET['challenge']       ?? '';
  34         $sec             =  $_GET['sec']             ?? '';
  35         $dfrn_version    = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
  36         $quiet                   = !empty($_GET['quiet']);
  37
  38         // Possibly it is an OStatus compatible server that requests a user feed
  39         $user_agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
  40         if (($a->argc > 1) && ($dfrn_id == '') && !strstr($user_agent, 'Friendica')) {
  41                 $nickname = $a->argv[1];
  42                 header("Content-type: application/atom+xml");
  43                 echo OStatus::feed($nickname, $last_update, 10);
  44                 exit();
  45         }
  46
  47         $direction = -1;
  48
  49         if (strpos($dfrn_id, ':') == 1) {
  50                 $direction = intval(substr($dfrn_id, 0, 1));
  51                 $dfrn_id = substr($dfrn_id, 2);
  52         }
  53
  54         $hidewall = false;
  55
  56         if (($dfrn_id === '') && empty($_POST['dfrn_id'])) {
  57                 if (Config::get('system', 'block_public') && !Session::isAuthenticated()) {
  58                         throw new \Friendica\Network\HTTPException\ForbiddenException();
  59                 }
  60
  61                 $user = '';
  62                 if ($a->argc > 1) {
  63                         $r = q("SELECT `hidewall`,`nickname` FROM `user` WHERE `user`.`nickname` = '%s' LIMIT 1",
  64                                 DBA::escape($a->argv[1])
  65                         );
  66                         if (!$r) {
  67                                 throw new \Friendica\Network\HTTPException\NotFoundException();
  68                         }
  69
  70                         $hidewall = ($r[0]['hidewall'] && !local_user());
  71
  72                         $user = $r[0]['nickname'];
  73                 }
  74
  75                 Logger::log('dfrn_poll: public feed request from ' . $_SERVER['REMOTE_ADDR'] . ' for ' . $user);
  76                 header("Content-type: application/atom+xml");
  77                 echo DFRN::feed('', $user, $last_update, 0, $hidewall);
  78                 exit();
  79         }
  80
  81         if (($type === 'profile') && (!strlen($sec))) {
  82                 $sql_extra = '';
  83                 switch ($direction) {
  84                         case -1:
  85                                 $sql_extra = sprintf(" AND ( `dfrn-id` = '%s' OR `issued-id` = '%s' ) ", DBA::escape($dfrn_id), DBA::escape($dfrn_id));
  86                                 $my_id = $dfrn_id;
  87                                 break;
  88                         case 0:
  89                                 $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
  90                                 $my_id = '1:' . $dfrn_id;
  91                                 break;
  92                         case 1:
  93                                 $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
  94                                 $my_id = '0:' . $dfrn_id;
  95                                 break;
  96                         default:
  97                                 $a->internalRedirect();
  98                                 break; // NOTREACHED
  99                 }
 100
 101                 $r = q("SELECT `contact`.*, `user`.`username`, `user`.`nickname`
 102                         FROM `contact` LEFT JOIN `user` ON `contact`.`uid` = `user`.`uid`
 103                         WHERE `contact`.`blocked` = 0 AND `contact`.`pending` = 0
 104                         AND `user`.`nickname` = '%s' $sql_extra LIMIT 1",
 105                         DBA::escape($a->argv[1])
 106                 );
 107
 108                 if (DBA::isResult($r)) {
 109                         $s = Network::fetchUrl($r[0]['poll'] . '?dfrn_id=' . $my_id . '&type=profile-check');
 110
 111                         Logger::log("dfrn_poll: old profile returns " . $s, Logger::DATA);
 112
 113                         if (strlen($s)) {
 114                                 $xml = XML::parseString($s);
 115
 116                                 if ((int)$xml->status === 1) {
 117                                         $_SESSION['authenticated'] = 1;
 118                                         $_SESSION['visitor_id'] = $r[0]['id'];
 119                                         $_SESSION['visitor_home'] = $r[0]['url'];
 120                                         $_SESSION['visitor_handle'] = $r[0]['addr'];
 121                                         $_SESSION['visitor_visiting'] = $r[0]['uid'];
 122                                         $_SESSION['my_url'] = $r[0]['url'];
 123
 124                                         Session::setVisitorsContacts();
 125
 126                                         if (!$quiet) {
 127                                                 info(L10n::t('%1$s welcomes %2$s', $r[0]['username'], $r[0]['name']) . EOL);
 128                                         }
 129
 130                                         // Visitors get 1 day session.
 131                                         $session_id = session_id();
 132                                         $expire = time() + 86400;
 133                                         q("UPDATE `session` SET `expire` = '%s' WHERE `sid` = '%s'",
 134                                                 DBA::escape($expire),
 135                                                 DBA::escape($session_id)
 136                                         );
 137                                 }
 138                         }
 139
 140                         $profile = (count($r) > 0 && isset($r[0]['nickname']) ? $r[0]['nickname'] : '');
 141                         if (!empty($destination_url)) {
 142                                 System::externalRedirect($destination_url);
 143                         } else {
 144                                 $a->internalRedirect('profile/' . $profile);
 145                         }
 146                 }
 147                 $a->internalRedirect();
 148         }
 149
 150         if ($type === 'profile-check' && $dfrn_version < 2.2) {
 151                 if ((strlen($challenge)) && (strlen($sec))) {
 152                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 153                         $r = q("SELECT * FROM `profile_check` WHERE `sec` = '%s' ORDER BY `expire` DESC LIMIT 1",
 154                                 DBA::escape($sec)
 155                         );
 156                         if (!DBA::isResult($r)) {
 157                                 System::xmlExit(3, 'No ticket');
 158                                 // NOTREACHED
 159                         }
 160
 161                         $orig_id = $r[0]['dfrn_id'];
 162                         if (strpos($orig_id, ':')) {
 163                                 $orig_id = substr($orig_id, 2);
 164                         }
 165
 166                         $c = q("SELECT * FROM `contact` WHERE `id` = %d LIMIT 1",
 167                                 intval($r[0]['cid'])
 168                         );
 169                         if (!DBA::isResult($c)) {
 170                                 System::xmlExit(3, 'No profile');
 171                         }
 172
 173                         $contact = $c[0];
 174
 175                         $sent_dfrn_id = hex2bin($dfrn_id);
 176                         $challenge = hex2bin($challenge);
 177
 178                         $final_dfrn_id = '';
 179
 180                         if (($contact['duplex']) && strlen($contact['prvkey'])) {
 181                                 openssl_private_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['prvkey']);
 182                                 openssl_private_decrypt($challenge, $decoded_challenge, $contact['prvkey']);
 183                         } else {
 184                                 openssl_public_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['pubkey']);
 185                                 openssl_public_decrypt($challenge, $decoded_challenge, $contact['pubkey']);
 186                         }
 187
 188                         $final_dfrn_id = substr($final_dfrn_id, 0, strpos($final_dfrn_id, '.'));
 189
 190                         if (strpos($final_dfrn_id, ':') == 1) {
 191                                 $final_dfrn_id = substr($final_dfrn_id, 2);
 192                         }
 193
 194                         if ($final_dfrn_id != $orig_id) {
 195                                 Logger::log('profile_check: ' . $final_dfrn_id . ' != ' . $orig_id, Logger::DEBUG);
 196                                 // did not decode properly - cannot trust this site
 197                                 System::xmlExit(3, 'Bad decryption');
 198                         }
 199
 200                         header("Content-type: text/xml");
 201                         echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?><dfrn_poll><status>0</status><challenge>$decoded_challenge</challenge><sec>$sec</sec></dfrn_poll>";
 202                         exit();
 203                         // NOTREACHED
 204                 } else {
 205                         // old protocol
 206                         switch ($direction) {
 207                                 case 1:
 208                                         $dfrn_id = '0:' . $dfrn_id;
 209                                         break;
 210                                 case 0:
 211                                         $dfrn_id = '1:' . $dfrn_id;
 212                                         break;
 213                                 default:
 214                                         break;
 215                         }
 216
 217                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 218                         $r = q("SELECT * FROM `profile_check` WHERE `dfrn_id` = '%s' ORDER BY `expire` DESC",
 219                                 DBA::escape($dfrn_id));
 220                         if (DBA::isResult($r)) {
 221                                 System::xmlExit(1);
 222                                 return; // NOTREACHED
 223                         }
 224                         System::xmlExit(0);
 225                         return; // NOTREACHED
 226                 }
 227         }
 228 }
 229
 230 function dfrn_poll_post(App $a)
 231 {
 232         $dfrn_id      =  $_POST['dfrn_id']   ?? '';
 233         $challenge    =  $_POST['challenge'] ?? '';
 234         $url          =  $_POST['url']       ?? '';
 235         $sec          =  $_POST['sec']       ?? '';
 236         $ptype        =  $_POST['type']      ?? '';
 237         $perm         = ($_POST['perm']      ?? '') ?: 'r';
 238         $dfrn_version = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
 239
 240         if ($ptype === 'profile-check') {
 241                 if (strlen($challenge) && strlen($sec)) {
 242                         Logger::log('dfrn_poll: POST: profile-check');
 243
 244                         DBA::delete('profile_check', ["`expire` < ?", time()]);
 245                         $r = q("SELECT * FROM `profile_check` WHERE `sec` = '%s' ORDER BY `expire` DESC LIMIT 1",
 246                                 DBA::escape($sec)
 247                         );
 248                         if (!DBA::isResult($r)) {
 249                                 System::xmlExit(3, 'No ticket');
 250                                 // NOTREACHED
 251                         }
 252
 253                         $orig_id = $r[0]['dfrn_id'];
 254                         if (strpos($orig_id, ':')) {
 255                                 $orig_id = substr($orig_id, 2);
 256                         }
 257
 258                         $c = q("SELECT * FROM `contact` WHERE `id` = %d LIMIT 1",
 259                                 intval($r[0]['cid'])
 260                         );
 261                         if (!DBA::isResult($c)) {
 262                                 System::xmlExit(3, 'No profile');
 263                         }
 264
 265                         $contact = $c[0];
 266
 267                         $sent_dfrn_id = hex2bin($dfrn_id);
 268                         $challenge = hex2bin($challenge);
 269
 270                         $final_dfrn_id = '';
 271
 272                         if ($contact['duplex'] && strlen($contact['prvkey'])) {
 273                                 openssl_private_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['prvkey']);
 274                                 openssl_private_decrypt($challenge, $decoded_challenge, $contact['prvkey']);
 275                         } else {
 276                                 openssl_public_decrypt($sent_dfrn_id, $final_dfrn_id, $contact['pubkey']);
 277                                 openssl_public_decrypt($challenge, $decoded_challenge, $contact['pubkey']);
 278                         }
 279
 280                         $final_dfrn_id = substr($final_dfrn_id, 0, strpos($final_dfrn_id, '.'));
 281
 282                         if (strpos($final_dfrn_id, ':') == 1) {
 283                                 $final_dfrn_id = substr($final_dfrn_id, 2);
 284                         }
 285
 286                         if ($final_dfrn_id != $orig_id) {
 287                                 Logger::log('profile_check: ' . $final_dfrn_id . ' != ' . $orig_id, Logger::DEBUG);
 288                                 // did not decode properly - cannot trust this site
 289                                 System::xmlExit(3, 'Bad decryption');
 290                         }
 291
 292                         header("Content-type: text/xml");
 293                         echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?><dfrn_poll><status>0</status><challenge>$decoded_challenge</challenge><sec>$sec</sec></dfrn_poll>";
 294                         exit();
 295                         // NOTREACHED
 296                 }
 297         }
 298
 299         $direction = -1;
 300         if (strpos($dfrn_id, ':') == 1) {
 301                 $direction = intval(substr($dfrn_id, 0, 1));
 302                 $dfrn_id = substr($dfrn_id, 2);
 303         }
 304
 305         $r = q("SELECT * FROM `challenge` WHERE `dfrn-id` = '%s' AND `challenge` = '%s' LIMIT 1",
 306                 DBA::escape($dfrn_id),
 307                 DBA::escape($challenge)
 308         );
 309
 310         if (!DBA::isResult($r)) {
 311                 exit();
 312         }
 313
 314         $type = $r[0]['type'];
 315         $last_update = $r[0]['last_update'];
 316
 317         DBA::delete('challenge', ['dfrn-id' => $dfrn_id, 'challenge' => $challenge]);
 318
 319         $sql_extra = '';
 320         switch ($direction) {
 321                 case -1:
 322                         $sql_extra = sprintf(" AND `issued-id` = '%s' ", DBA::escape($dfrn_id));
 323                         break;
 324                 case 0:
 325                         $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 326                         break;
 327                 case 1:
 328                         $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 329                         break;
 330                 default:
 331                         $a->internalRedirect();
 332                         break; // NOTREACHED
 333         }
 334
 335         $r = q("SELECT * FROM `contact` WHERE `blocked` = 0 AND `pending` = 0 $sql_extra LIMIT 1");
 336         if (!DBA::isResult($r)) {
 337                 exit();
 338         }
 339
 340         $contact = $r[0];
 341         $owner_uid = $r[0]['uid'];
 342         $contact_id = $r[0]['id'];
 343
 344         if ($type === 'reputation' && strlen($url)) {
 345                 $r = q("SELECT * FROM `contact` WHERE `url` = '%s' AND `uid` = %d LIMIT 1",
 346                         DBA::escape($url),
 347                         intval($owner_uid)
 348                 );
 349                 $reputation = 0;
 350                 $text = '';
 351
 352                 if (DBA::isResult($r)) {
 353                         $reputation = $r[0]['rating'];
 354                         $text = $r[0]['reason'];
 355
 356                         if ($r[0]['id'] == $contact_id) { // inquiring about own reputation not allowed
 357                                 $reputation = 0;
 358                                 $text = '';
 359                         }
 360                 }
 361
 362                 echo "<?xml version=\"1.0\" encoding=\"UTF-8\"?>
 363                 <reputation>
 364                         <url>$url</url>
 365                         <rating>$reputation</rating>
 366                         <description>$text</description>
 367                 </reputation>
 368                 ";
 369                 exit();
 370                 // NOTREACHED
 371         } else {
 372                 // Update the writable flag if it changed
 373                 Logger::log('dfrn_poll: post request feed: ' . print_r($_POST, true), Logger::DATA);
 374                 if ($dfrn_version >= 2.21) {
 375                         if ($perm === 'rw') {
 376                                 $writable = 1;
 377                         } else {
 378                                 $writable = 0;
 379                         }
 380
 381                         if ($writable != $contact['writable']) {
 382                                 q("UPDATE `contact` SET `writable` = %d WHERE `id` = %d",
 383                                         intval($writable),
 384                                         intval($contact_id)
 385                                 );
 386                         }
 387                 }
 388
 389                 header("Content-type: application/atom+xml");
 390                 $o = DFRN::feed($dfrn_id, $a->argv[1], $last_update, $direction);
 391                 echo $o;
 392                 exit();
 393         }
 394 }
 395
 396 function dfrn_poll_content(App $a)
 397 {
 398         $dfrn_id         =  $_GET['dfrn_id']         ?? '';
 399         $type            = ($_GET['type']            ?? '') ?: 'data';
 400         $last_update     =  $_GET['last_update']     ?? '';
 401         $destination_url =  $_GET['destination_url'] ?? '';
 402         $sec             =  $_GET['sec']             ?? '';
 403         $dfrn_version    = floatval(($_GET['dfrn_version'] ?? 0.0) ?: 2.0);
 404         $quiet           = !empty($_GET['quiet']);
 405
 406         $direction = -1;
 407         if (strpos($dfrn_id, ':') == 1) {
 408                 $direction = intval(substr($dfrn_id, 0, 1));
 409                 $dfrn_id = substr($dfrn_id, 2);
 410         }
 411
 412         if ($dfrn_id != '') {
 413                 // initial communication from external contact
 414                 $hash = Strings::getRandomHex();
 415
 416                 $status = 0;
 417
 418                 DBA::delete('challenge', ["`expire` < ?", time()]);
 419
 420                 if ($type !== 'profile') {
 421                         q("INSERT INTO `challenge` ( `challenge`, `dfrn-id`, `expire` , `type`, `last_update` )
 422                                 VALUES( '%s', '%s', '%s', '%s', '%s' ) ",
 423                                 DBA::escape($hash),
 424                                 DBA::escape($dfrn_id),
 425                                 intval(time() + 60 ),
 426                                 DBA::escape($type),
 427                                 DBA::escape($last_update)
 428                         );
 429                 }
 430
 431                 $sql_extra = '';
 432                 switch ($direction) {
 433                         case -1:
 434                                 if ($type === 'profile') {
 435                                         $sql_extra = sprintf(" AND (`dfrn-id` = '%s' OR `issued-id` = '%s') ", DBA::escape($dfrn_id), DBA::escape($dfrn_id));
 436                                 } else {
 437                                         $sql_extra = sprintf(" AND `issued-id` = '%s' ", DBA::escape($dfrn_id));
 438                                 }
 439
 440                                 $my_id = $dfrn_id;
 441                                 break;
 442                         case 0:
 443                                 $sql_extra = sprintf(" AND `issued-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 444                                 $my_id = '1:' . $dfrn_id;
 445                                 break;
 446                         case 1:
 447                                 $sql_extra = sprintf(" AND `dfrn-id` = '%s' AND `duplex` = 1 ", DBA::escape($dfrn_id));
 448                                 $my_id = '0:' . $dfrn_id;
 449                                 break;
 450                         default:
 451                                 $a->internalRedirect();
 452                                 break; // NOTREACHED
 453                 }
 454
 455                 $nickname = $a->argv[1];
 456
 457                 $r = q("SELECT `contact`.*, `user`.`username`, `user`.`nickname`
 458                         FROM `contact` LEFT JOIN `user` ON `contact`.`uid` = `user`.`uid`
 459                         WHERE `contact`.`blocked` = 0 AND `contact`.`pending` = 0
 460                         AND `user`.`nickname` = '%s' $sql_extra LIMIT 1",
 461                         DBA::escape($nickname)
 462                 );
 463                 if (DBA::isResult($r)) {
 464                         $challenge = '';
 465                         $encrypted_id = '';
 466                         $id_str = $my_id . '.' . mt_rand(1000, 9999);
 467
 468                         if (($r[0]['duplex'] && strlen($r[0]['pubkey'])) || !strlen($r[0]['prvkey'])) {
 469                                 openssl_public_encrypt($hash, $challenge, $r[0]['pubkey']);
 470                                 openssl_public_encrypt($id_str, $encrypted_id, $r[0]['pubkey']);
 471                         } else {
 472                                 openssl_private_encrypt($hash, $challenge, $r[0]['prvkey']);
 473                                 openssl_private_encrypt($id_str, $encrypted_id, $r[0]['prvkey']);
 474                         }
 475
 476                         $challenge = bin2hex($challenge);
 477                         $encrypted_id = bin2hex($encrypted_id);
 478                 } else {
 479                         $status = 1;
 480                         $challenge = '';
 481                         $encrypted_id = '';
 482                 }
 483
 484                 if (($type === 'profile') && (strlen($sec))) {
 485                         // heluecht: I don't know why we don't fail immediately when the user or contact hadn't been found.
 486                         // Since it doesn't make sense to continue from this point on, we now fail here. This should be safe.
 487                         if (!DBA::isResult($r)) {
 488                                 throw new \Friendica\Network\HTTPException\NotFoundException();
 489                         }
 490
 491                         // URL reply
 492                         if ($dfrn_version < 2.2) {
 493                                 $s = Network::fetchUrl($r[0]['poll']
 494                                         . '?dfrn_id=' . $encrypted_id
 495                                         . '&type=profile-check'
 496                                         . '&dfrn_version=' . DFRN_PROTOCOL_VERSION
 497                                         . '&challenge=' . $challenge
 498                                         . '&sec=' . $sec
 499                                 );
 500                         } else {
 501                                 $s = Network::post($r[0]['poll'], [
 502                                         'dfrn_id' => $encrypted_id,
 503                                         'type' => 'profile-check',
 504                                         'dfrn_version' => DFRN_PROTOCOL_VERSION,
 505                                         'challenge' => $challenge,
 506                                         'sec' => $sec
 507                                 ])->getBody();
 508                         }
 509
 510                         Logger::log("dfrn_poll: sec profile: " . $s, Logger::DATA);
 511
 512                         if (strlen($s) && strstr($s, '<?xml')) {
 513                                 $xml = XML::parseString($s);
 514
 515                                 Logger::log('dfrn_poll: profile: parsed xml: ' . print_r($xml, true), Logger::DATA);
 516
 517                                 Logger::log('dfrn_poll: secure profile: challenge: ' . $xml->challenge . ' expecting ' . $hash);
 518                                 Logger::log('dfrn_poll: secure profile: sec: ' . $xml->sec . ' expecting ' . $sec);
 519
 520                                 if (((int) $xml->status == 0) && ($xml->challenge == $hash) && ($xml->sec == $sec)) {
 521                                         $_SESSION['authenticated'] = 1;
 522                                         $_SESSION['visitor_id'] = $r[0]['id'];
 523                                         $_SESSION['visitor_home'] = $r[0]['url'];
 524                                         $_SESSION['visitor_visiting'] = $r[0]['uid'];
 525                                         $_SESSION['my_url'] = $r[0]['url'];
 526
 527                                         Session::setVisitorsContacts();
 528
 529                                         if (!$quiet) {
 530                                                 info(L10n::t('%1$s welcomes %2$s', $r[0]['username'], $r[0]['name']) . EOL);
 531                                         }
 532
 533                                         // Visitors get 1 day session.
 534                                         $session_id = session_id();
 535                                         $expire = time() + 86400;
 536                                         q("UPDATE `session` SET `expire` = '%s' WHERE `sid` = '%s'",
 537                                                 DBA::escape($expire),
 538                                                 DBA::escape($session_id)
 539                                         );
 540                                 }
 541                         }
 542
 543                         $profile = ((DBA::isResult($r) && $r[0]['nickname']) ? $r[0]['nickname'] : $nickname);
 544
 545                         switch ($destination_url) {
 546                                 case 'profile':
 547                                         $a->internalRedirect('profile/' . $profile . '?f=&tab=profile');
 548                                         break;
 549                                 case 'photos':
 550                                         $a->internalRedirect('photos/' . $profile);
 551                                         break;
 552                                 case 'status':
 553                                 case '':
 554                                         $a->internalRedirect('profile/' . $profile);
 555                                         break;
 556                                 default:
 557                                         $appendix = (strstr($destination_url, '?') ? '&f=&redir=1' : '?f=&redir=1');
 558                                         $a->redirect($destination_url . $appendix);
 559                                         break;
 560                         }
 561                         // NOTREACHED
 562                 } else {
 563                         // XML reply
 564                         header("Content-type: text/xml");
 565                         echo '<?xml version="1.0" encoding="UTF-8"?>' . "\r\n"
 566                                 . '<dfrn_poll>' . "\r\n"
 567                                 . "\t" . '<status>' . $status . '</status>' . "\r\n"
 568                                 . "\t" . '<dfrn_version>' . DFRN_PROTOCOL_VERSION . '</dfrn_version>' . "\r\n"
 569                                 . "\t" . '<dfrn_id>' . $encrypted_id . '</dfrn_id>' . "\r\n"
 570                                 . "\t" . '<challenge>' . $challenge . '</challenge>' . "\r\n"
 571                                 . '</dfrn_poll>' . "\r\n";
 572                         exit();
 573                         // NOTREACHED
 574                 }
 575         }
 576 }