修复shadowsocks的udp传输错误问题, fix #201

该问题来自vs的一个超陈旧的 udp bug，应该是自从实现了dns功能之后就存在了

当时写错了，把拷贝buf的方向写反了，而且错误地返回了EOF

同时realTargetAddr的network从dual写为udp的位置也需要提前

而且ss实际上不需要也不可能自己处理拨号。

我真是太笨拙了, 犯下这么多错。

main.go

@@ -1195,7 +1195,12 @@ func dialClient(iics incomingInserverConnState, targetAddr netLayer.Addr,
 
 	var dialedCommonConn any
 
-	not_dial_here := !(realTargetAddr.Network == "udp" && client.GetCreator().UseUDPAsMsgConn())
+	switch realTargetAddr.Network {
+	case netLayer.DualNetworkName:
+		realTargetAddr.Network = targetAddr.Network
+	}
+
+	dialhere := !(realTargetAddr.Network == "udp" && client.GetCreator().UseUDPAsMsgConn())
 
 	/*
 		direct和shadowsocks的udp是自己拨号的，因为它用到了udp的包特性
@@ -1210,7 +1215,7 @@ func dialClient(iics incomingInserverConnState, targetAddr netLayer.Addr,
 
 	var muxC advLayer.MuxClient
 
-	if not_dial_here {
+	if dialhere {
 
 		if adv != "" && advClient.IsMux() {
 

netLayer/udpConn.go

@@ -136,8 +136,8 @@ func (uc *UDPConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
 		if !ok {
 			return 0, uc.peerAddr, io.EOF
 		}
-		n = copy(msg.Data, p)
-		return n, uc.peerAddr, io.EOF
+		n = copy(p, msg.Data)
+		return n, uc.peerAddr, nil //io.EOF
 
 	case <-uc.readDeadline.Wait():
 		return 0, uc.peerAddr, os.ErrDeadlineExceeded

proxy/shadowsocks/client.go

@@ -18,7 +18,7 @@ func init() {
 type ClientCreator struct{ proxy.CreatorCommonStruct }
 
 func (ClientCreator) UseUDPAsMsgConn() bool {
-	return true
+	return false
 }
 func (ClientCreator) MultiTransportLayer() bool {
 	return true