From a0c2ddfd1b93037f73bac751866ea2a81c3f3984 Mon Sep 17 00:00:00 2001
From: mykola2312 <49044616+mykola2312@users.noreply.github.com>
Date: Sun, 3 Apr 2022 18:12:04 +0300
Subject: [PATCH] implemented UDP tracker protocol & re-tracker
 proxy-announcing for UDP

---
 tracker.php | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/tracker.php b/tracker.php
index e943096..49d1947 100644
--- a/tracker.php
+++ b/tracker.php
@@ -2,8 +2,6 @@
 require("../php/config.php");
 require("bencoder.php");
 require("peer.php");
-$ANN_USERAGENT = "Transmission/3.00";
-$ANN_PEER_ID = "01234567890123456789";
 $DB_NAME = "torrent";
 
 class Tracker {
@@ -34,7 +32,7 @@ class Tracker {
         return false;
     }
 
-    public function doHttpAnnounce($infoHash, $peerIp, $peerPort, $peerId = null, $uploaded = 0, $downloaded = 0, $left = 0) {
+    protected function doHttpAnnounce($infoHash, $peerIp, $peerPort, $peerId = null, $uploaded = 0, $downloaded = 0, $left = 0) {
         $peers = array();
 
         $passkey = is_null($this->passkey) ? "" : $this->passkey . "&";
@@ -80,9 +78,57 @@ class Tracker {
         return $peers;
     }
 
+    protected function doUdpAnnounce($infoHash, $peerIp, $peerPort, $peerId = null, $uploaded = 0, $downloaded = 0, $left = 0) {
+        $peers = array();
+
+        $addr = gethostbyname($this->host);
+        $port = $this->port;
+        $key = 0;
+
+        $sockfd = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
+        socket_set_option($sockfd, SOL_SOCKET, SO_RCVTIMEO,
+            array("sec" => 1, "usec" => 0));
+
+        $transaction_id = rand();
+        $req = pack("JNN", 4497486125440, 0, $transaction_id);
+        socket_sendto($sockfd, $req, 16, 0, $addr, $port);
+        $recv = socket_recvfrom($sockfd, $buf, 16, 0, $addr, $port);
+        if ($recv == false || $recv == 0) {
+            return false;
+        }
+        $res = unpack("Naction/Ntransaction_id/Jconnection_id", $buf);
+        $connection_id = $res["connection_id"];
+
+        $transaction_id = rand();
+        $req = pack("JNN", $connection_id, 1, $transaction_id)
+            . hex2bin($infoHash)
+            . (is_null($peerId) ? self::ANN_PEER_ID : $peerId)
+            . pack("JJJNNNNn", $downloaded, $uploaded, $left,
+                0, $peerIp, $key, -1, $peerPort);
+        socket_sendto($sockfd, $req, 98, 0, $addr, $port);
+        $recv = socket_recvfrom($sockfd, $buf, 65535, 0, $addr, $port);
+        if ($recv == false || $recv == 0) {
+            return false;
+        }
+        $res = unpack("Naction/Ntransaction_id/Ninterval/Nleechers/Nseeders", $buf);
+        //$count = $res["leechers"] + $res["seeders"];
+        $count = ($res - 20) / 6;
+        for ($i = 0; $i < $count; $i++) {
+            $peer = unpack("Nip/nport", $buf, 20 + $i*6);
+            array_push($peers, new Peer($infoHash,
+                long2ip($peer["ip"]), $peer["port"]));
+        }
+
+        socket_close($sockfd);
+
+        return $peers;
+    }
+
     public function announce($infoHash, $peerIp, $peerPort, $peerId = null, $uploaded = 0, $downloaded = 0, $left = 0) {
         if ($this->proto == "http" || $this->proto == "https") {
             return $this->doHttpAnnounce($infoHash, $peerIp, $peerPort, $peerId, $uploaded, $downloaded, $left);
+        } else if ($this->proto == "udp") {
+            return $this->doUdpAnnounce($infoHash, $peerIp, $peerPort, $peerId, $uploaded, $downloaded, $left);
         }
 
         return false;