From d14f85d4ecf356c7189917f20edfb23577dd2afa Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Mon, 27 Jun 2016 17:47:27 +0700
Subject: [PATCH] fix race condition in ReceivedPacketHistory

---
 ackhandlernew/received_packet_history.go | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/ackhandlernew/received_packet_history.go b/ackhandlernew/received_packet_history.go
index 608703da..1e417ed6 100644
--- a/ackhandlernew/received_packet_history.go
+++ b/ackhandlernew/received_packet_history.go
@@ -1,6 +1,8 @@
 package ackhandlernew
 
 import (
+	"sync"
+
 	"github.com/lucas-clemente/quic-go/frames"
 	"github.com/lucas-clemente/quic-go/protocol"
 	"github.com/lucas-clemente/quic-go/utils"
@@ -8,6 +10,8 @@ import (
 
 type receivedPacketHistory struct {
 	ranges *utils.PacketIntervalList
+
+	mutex sync.RWMutex
 }
 
 // newReceivedPacketHistory creates a new received packet history
@@ -19,6 +23,9 @@ func newReceivedPacketHistory() *receivedPacketHistory {
 
 // ReceivedPacket registers a packet with PacketNumber p and updates the ranges
 func (h *receivedPacketHistory) ReceivedPacket(p protocol.PacketNumber) {
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+
 	if h.ranges.Len() == 0 {
 		h.ranges.PushBack(utils.PacketInterval{Start: p, End: p})
 		return
@@ -62,6 +69,9 @@ func (h *receivedPacketHistory) ReceivedPacket(p protocol.PacketNumber) {
 }
 
 func (h *receivedPacketHistory) DeleteBelow(leastUnacked protocol.PacketNumber) {
+	h.mutex.Lock()
+	defer h.mutex.Unlock()
+
 	nextEl := h.ranges.Front()
 	for el := h.ranges.Front(); nextEl != nil; el = nextEl {
 		nextEl = el.Next()
@@ -79,6 +89,9 @@ func (h *receivedPacketHistory) DeleteBelow(leastUnacked protocol.PacketNumber)
 
 // GetAckRanges gets a slice of all AckRanges that can be used in an AckFrame
 func (h *receivedPacketHistory) GetAckRanges() []frames.AckRange {
+	h.mutex.RLock()
+	defer h.mutex.RUnlock()
+
 	if h.ranges.Len() == 0 {
 		return nil
 	}