udp: Implement initial connection protocol

udp/udp.go

@@ -0,0 +1,70 @@
+// Copyright 2015 The Chihaya Authors. All rights reserved.
+// Use of this source code is governed by the BSD 2-Clause license,
+// which can be found in the LICENSE file.
+
+// Package udp implements a UDP BitTorrent tracker per BEP 15 and BEP 41.
+// IPv6 is currently unsupported as there is no widely-implemented standard.
+package udp
+
+import (
+	"net"
+
+	"github.com/golang/glog"
+	"github.com/pushrax/bufferpool"
+
+	"github.com/chihaya/chihaya/config"
+	"github.com/chihaya/chihaya/tracker"
+)
+
+// Server represents a UDP torrent tracker.
+type Server struct {
+	config  *config.Config
+	tracker *tracker.Tracker
+}
+
+func (srv *Server) ListenAndServe() error {
+	listenAddr, err := net.ResolveUDPAddr("udp", srv.config.UDPListenAddr)
+	if err != nil {
+		return err
+	}
+
+	sock, err := net.ListenUDP("udp", listenAddr)
+	defer sock.Close()
+	if err != nil {
+		return err
+	}
+
+	if srv.config.UDPReadBufferSize > 0 {
+		sock.SetReadBuffer(srv.config.UDPReadBufferSize)
+	}
+
+	pool := bufferpool.New(1000, 2048)
+
+	for {
+		buffer := pool.TakeSlice()
+		n, addr, err := sock.ReadFromUDP(buffer)
+		if err != nil {
+			return err
+		}
+
+		go func() {
+			response := srv.handlePacket(buffer[:n], addr)
+			if response != nil {
+				sock.WriteToUDP(response, addr)
+			}
+			pool.GiveSlice(buffer)
+		}()
+	}
+}
+
+func Serve(cfg *config.Config, tkr *tracker.Tracker) {
+	srv := &Server{
+		config:  cfg,
+		tracker: tkr,
+	}
+
+	glog.V(0).Info("Starting UDP on ", cfg.UDPListenAddr)
+	if err := srv.ListenAndServe(); err != nil {
+		glog.Errorf("Failed to run UDP server: %s", err.Error())
+	}
+}