Add announcePeer feature.

TODO:
	fix sync write
	congestion control
	Request timeout

client/dial.go

@@ -63,10 +63,13 @@ func (dp *dialPool) stop() {
 
 func (dp *dialPool) connectLoop(ctx context.Context) {
 	dhtCtx, cancel := context.WithTimeout(ctx, dhtTimeout)
-	// TODO: handle tokens
-	addrs, _, err := dp.dht.GetPeers(dhtCtx, dp.infoHash)
+	addrs, tokens, err := dp.dht.GetPeers(dhtCtx, dp.infoHash)
 	cancel()
 
+	if len(tokens) > 0 {
+		dp.dht.AnnouncePeer(ctx, dp.infoHash, tokens)
+	}
+
 	if err != nil {
 		select {
 		case dp.results <- dialResult{done: true, err: err}:

client/torrent.go

@@ -26,7 +26,7 @@ const (
 
 const (
 	maxPeers      = 8
-	maxPending    = 5
+	maxPending    = 50
 	dialTimeout   = 30 * time.Second
 	retryInterval = 30 * time.Second
 	dhtTimeout    = 5 * time.Minute