Add announcePeer feature.

TODO:
	fix sync write
	congestion control
	Request timeout

dht/dht.go

@@ -8,6 +8,8 @@ import (
 	"strconv"
 	"sync"
 	"time"
+
+	"storrent/utp"
 )
 
 const (
@@ -18,39 +20,27 @@ const (
 
 type DHT struct {
 	conn    *net.UDPConn
+	in      <-chan utp.Packet
 	id      [20]byte
 	nodes   []node
 	pending map[string]chan *resp
 	mu      sync.Mutex
 }
 
-func New(port int) (*DHT, error) {
-	addr := &net.UDPAddr{Port: port}
-	conn, err := net.ListenUDP("udp", addr)
-	if err != nil {
-		return nil, err
-	}
+func New(conn *net.UDPConn, in <-chan utp.Packet) *DHT {
 	d := &DHT{
 		conn:    conn,
+		in:      in,
 		id:      genNodeID(),
 		pending: make(map[string]chan *resp),
 	}
 	go d.run()
-	return d, nil
-}
-
-func (d *DHT) Close() {
-	d.conn.Close()
+	return d
 }
 
 func (d *DHT) run() {
-	buf := make([]byte, 65535)
-	for {
-		n, _, err := d.conn.ReadFromUDP(buf)
-		if err != nil {
-			return
-		}
-		msg, err := decodeMsg(buf[:n])
+	for pkt := range d.in {
+		msg, err := decodeMsg(pkt.Raw)
 		if err != nil {
 			continue
 		}
@@ -237,3 +227,23 @@ func nextCandidate(candidates []node, queried map[string]bool) (node, int) {
 	}
 	return node{}, -1
 }
+
+func (d *DHT) AnnouncePeer(ctx context.Context, h [20]byte, tokens map[string]string) {
+	var wg sync.WaitGroup
+	for addrStr, token := range tokens {
+		addr, err := net.ResolveUDPAddr("udp", addrStr)
+		if err != nil {
+			continue
+		}
+		wg.Add(1)
+		go func(addr *net.UDPAddr, token string) {
+			defer wg.Done()
+			d.query(ctx, addr, announcePeer, args{
+				InfoHash:    h,
+				ImpliedPort: 1,
+				Token:       token,
+			})
+		}(addr, token)
+	}
+	wg.Wait()
+}