From c7b0264f9a52718c198045922bd53c8faffaa2b4 Mon Sep 17 00:00:00 2001
From: v2ray <admin@v2ray.com>
Date: Wed, 13 Jul 2016 21:39:18 +0200
Subject: [PATCH] lock in udp hub

---
 transport/internet/udp/udp.go | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/transport/internet/udp/udp.go b/transport/internet/udp/udp.go
index d16ea6981..874b8e5dd 100644
--- a/transport/internet/udp/udp.go
+++ b/transport/internet/udp/udp.go
@@ -2,6 +2,7 @@ package udp
 
 import (
 	"net"
+	"sync"
 
 	"github.com/v2ray/v2ray-core/common/alloc"
 	v2net "github.com/v2ray/v2ray-core/common/net"
@@ -10,6 +11,7 @@ import (
 type UDPPayloadHandler func(*alloc.Buffer, v2net.Destination)
 
 type UDPHub struct {
+	sync.RWMutex
 	conn      *net.UDPConn
 	callback  UDPPayloadHandler
 	accepting bool
@@ -32,6 +34,9 @@ func ListenUDP(address v2net.Address, port v2net.Port, callback UDPPayloadHandle
 }
 
 func (this *UDPHub) Close() {
+	this.Lock()
+	defer this.Unlock()
+
 	this.accepting = false
 	this.conn.Close()
 }
@@ -44,8 +49,11 @@ func (this *UDPHub) WriteTo(payload []byte, dest v2net.Destination) (int, error)
 }
 
 func (this *UDPHub) start() {
+	this.Lock()
 	this.accepting = true
-	for this.accepting {
+	this.Unlock()
+
+	for this.Running() {
 		buffer := alloc.NewBuffer()
 		nBytes, addr, err := this.conn.ReadFromUDP(buffer.Value)
 		if err != nil {
@@ -57,3 +65,10 @@ func (this *UDPHub) start() {
 		go this.callback(buffer, dest)
 	}
 }
+
+func (this *UDPHub) Running() bool {
+	this.RLock()
+	defer this.RUnlock()
+
+	return this.accepting
+}