BitTorrent: Download not starting

Question

I am trying to implement a bittorrent tracker in Laravel. However, I am stuck at the moment as the download won't start. There is one peer which it appears to be seeding and I am 100% sure that it is connectable. But, when I run a second client on a different machine, the download won't start. It is stuck at "Connecting to peers" (uTorrent).

From the tracker I am sending the following response when the client makes an announce:

d8:intervali1000e12:min intervali300e5:peers18:�ؤ�i�ؑ�XÚJU�6e 

In the downloading client I have the following data:

Here's my announce code:

<?php  namespace App\Http\Controllers\Announce;  use App\Helpers\BencodeHelper; use App\Models\Peer; use App\Models\PeerTorrent; use App\Models\Torrent; use App\Models\User; use Illuminate\Http\Request; use Illuminate\Http\Response; use Illuminate\Routing\Controller; use Illuminate\Support\Facades\Input; use Illuminate\Support\Facades\Log;  class AnnounceController extends Controller {     const __INTERVAL = 1000;     const __TIMEOUT = 120;     const __INTERVAL_MIN = 60;     const __MAX_PPR = 20;      public function announce(Request $request)     {         Log::info($request->fullUrl());         $status = 200;         $content = "";         $passkey = Input::get('passkey');         $peer_id = Input::get('peer_id');         $port = Input::get('port');         $info_hash = Input::get('info_hash');         $downloaded = Input::get('uploaded') ? intval(Input::get('uploaded')) : 0;         $uploaded = Input::get('uploaded') ? intval(Input::get('uploaded')) : 0;         $left = Input::get('left') ? intval(Input::get('left')) : 0;         $compact = Input::get('compact') ? intval(Input::get('compact')) : 0;         $no_peer_id = Input::get('no_peer_id') ? intval(Input::get('no_peer_id')) : 0;          $ipAddress = '';         // Check for X-Forwarded-For headers and use those if found         if (isset($_SERVER['HTTP_X_FORWARDED_FOR']) && ('' !== trim($_SERVER['HTTP_X_FORWARDED_FOR']))) {             $ipAddress = (trim($_SERVER['HTTP_X_FORWARDED_FOR']));         } else {             if (isset($_SERVER['REMOTE_ADDR']) && ('' !== trim($_SERVER['REMOTE_ADDR']))) {                 $ipAddress = (trim($_SERVER['REMOTE_ADDR']));             }         }          $port = $_SERVER['REMOTE_PORT'];         /*if(!$port || !ctype_digit($port) || intval($port) < 1 || intval($port) > 65535)         {             $content = BencodeHelper::track("Invalid client port.");             $status = 401;             return (new Response(AnnounceController::track($content), $status))                 ->header('Content-Type', $value);         }          if ($port == 999 && substr($peer_id, 0, 10) == '-TO0001-XX') {             die("d8:completei0e10:incompletei0e8:intervali600e12:min intervali60e5:peersld2:ip12:72.14.194.184:port3:999ed2:ip11:72.14.194.14:port3:999ed2:ip12:72.14.194.654:port3:999eee");         }*/           if (!$passkey) {             $content = BencodeHelper::track("Missing passkey.");             $status = 401;             return (new Response(AnnounceController::track($content), $status))                 ->header('Content-Type', $value);         }           $torrent = Torrent::getByInfoHash(sha1($info_hash));         if (!$torrent || $torrent == null) {             $content = "Torrent not registered with this tracker.";             $status = 404;             return (new Response(AnnounceController::track($content), $status))                 ->header('Content-Type', $value);         }          $user = User::has('passkeys', '=', $passkey)->get();          if ($user == null) {             $content = BencodeHelper::track("Invalid passkey.");             $status = 401;             return (new Response(AnnounceController::track($content), $status))                 ->header('Content-Type', $value);         }          $peer = Peer::getByHashAndPasskey(bin2hex($peer_id), $passkey);          if ($peer == null) {             $peer = Peer::create([                 'hash' => bin2hex($peer_id),                 'user_agent' => $_SERVER['HTTP_USER_AGENT'],                 'ip_address' => $ipAddress,                 'passkey' => $passkey,                 'port' => $port             ]);         }          if (!$info_hash || strlen($info_hash) != 20) {             $content = BencodeHelper::track("Invalid info_hash.");             $status = 401;             return (new Response(AnnounceController::track($content), $status))                 ->header('Content-Type', $value);         }           $peer_torrent = PeerTorrent::getByPeerAndTorrent($peer, $torrent);          if ($peer_torrent == null) {             $peer_torrent = PeerTorrent::create([                 'peer_id' => $peer->id,                 'torrent_id' => $torrent->id,                 'uploaded' => $uploaded,                 'downloaded' => $downloaded,                 'left' => $left,                 'stopped' => false             ]);          } else {             $peer_torrent->uploaded = $uploaded;             $peer_torrent->downloaded = $downloaded;             $peer_torrent->left = $left;             $peer_torrent->save();         }          $seeders = $torrent->getSeedersCount();         $leechers = $torrent->getLeechersCount();         $resp = "";         if ($compact != 1) {             $resp = "d" . $this->benc_str("interval") . "i" . AnnounceController::__INTERVAL . "e" . $this->benc_str("peers") . "l";         } else {             $resp = "d" . $this->benc_str("interval") . "i" . AnnounceController::__INTERVAL . "e" . $this->benc_str("min interval") . "i" . 300 . "e5:" . "peers";         }          $peer = array();          $peer_num = 0;         foreach ($torrent->getPeersArray() as $row) {             if ($compact != 1) {                 if ($row["peer_id"] === $peer->hash) {                     continue;                 }                  $resp .= "d" . $this->benc_str("ip") . $this->benc_str($row['ip']);                  if ($no_peer_id == 0) {                     $resp .= $this->benc_str("peer id") . $this->benc_str($row["peer_id"]);                 }                  $resp .= $this->benc_str("port") . "i" . $row["port"] . "e" . "e";              } else {                 $peer_ip = explode('.', $row["ip"]);                 $peer_ip = pack("C*", $peer_ip[0], $peer_ip[1], $peer_ip[2], $peer_ip[3]);                 $peer_port = pack("n*", (int)$row["port"]);                 $time = intval((time() % 7680) / 60);                  if ($left == 0) {                     $time += 128;                 }                  $time = pack("C", $time);                 $peer[] = $time . $peer_ip . $peer_port;                 $peer_num++;             }         }          if ($compact != 1) {             $resp .= "ee";         } else {             $o = "";             for ($i = 0; $i < $peer_num; $i++) {                 $o .= substr($peer[$i], 1, 6);             }             $resp .= strlen($o) . ':' . $o . 'e';         }          $this->benc_resp_raw($resp);     }      public function benc_resp($d)     {         return $this->benc_resp_raw($this->benc(array('type' => 'dictionary', 'value' => $d)));     }      public function benc_resp_raw($x)     {         header("Content-Type: text/plain");         header("Pragma: no-cache");          if ($_SERVER['HTTP_ACCEPT_ENCODING'] == 'gzip') {             header("Content-Encoding: gzip");             echo gzencode($x, 9, FORCE_GZIP);         } else {             echo $x;         }     }      function benc($obj)     {         if (!is_array($obj) || !isset($obj["type"]) || !isset($obj["value"]))             return;         $c = $obj["value"];         switch ($obj["type"]) {             case "string":                 return $this->benc_str($c);             case "integer":                 return $this->benc_int($c);             case "list":                 return $this->benc_list($c);             case "dictionary":                 return $this->benc_dict($c);             default:                 return;         }     }      public function benc_str($s)     {         return strlen($s) . ":$s";     }      public function benc_int($i)     {         return "i" . $i . "e";     }      public function benc_list($a)     {         $s = "l";         foreach ($a as $e) {             $s .= $this->benc($e);         }         $s .= "e";         return $s;     }      public function benc_dict($d)     {         $s = "d";         $keys = array_keys($d);         sort($keys);         foreach ($keys as $k) {             $v = $d[$k];             $s .= $this->benc_str($k);             $s .= $this->benc($v);         }         $s .= "e";         return $s;     }       public function hex2bin($hex)     {         $r = '';         for ($i = 0; $i < strlen($hex); $i += 2) {             $r .= chr(hexdec($hex{$i} . $hex{($i + 1)}));         }         return $r;     } } 

I am not quite sure what am I missing here.

Answer 1

Maybe it's because you constantly set

->header('Content-Type', $value); 

without ever setting $value? So the "Announce-Response" is malformed?