From 2329d0e21e1a5bd2b16dab0c9796984ab40d1e40 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Sun, 25 Aug 2019 16:08:50 +0700
Subject: [PATCH] handle negative max_ack_delay values in the transport
 parameters

---
 internal/handshake/transport_parameter_test.go | 11 +++++++++++
 internal/handshake/transport_parameters.go     |  6 ++++++
 internal/wire/ack_frame.go                     |  3 +--
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/internal/handshake/transport_parameter_test.go b/internal/handshake/transport_parameter_test.go
index 48ccc3711..b75749666 100644
--- a/internal/handshake/transport_parameter_test.go
+++ b/internal/handshake/transport_parameter_test.go
@@ -190,6 +190,17 @@ var _ = Describe("Transport Parameters", func() {
 		Expect(err.Error()).To(ContainSubstring("inconsistent transport parameter length"))
 	})
 
+	It("handles max_ack_delays that decode to a negative duration", func() {
+		b := &bytes.Buffer{}
+		val := uint64(math.MaxUint64) / 5
+		utils.BigEndian.WriteUint16(b, uint16(maxAckDelayParameterID))
+		utils.BigEndian.WriteUint16(b, uint16(utils.VarIntLen(val)))
+		utils.WriteVarInt(b, val)
+		p := &TransportParameters{}
+		Expect(p.Unmarshal(prependLength(b.Bytes()), protocol.PerspectiveServer)).To(Succeed())
+		Expect(p.MaxAckDelay).To(BeNumerically(">", 290*365*24*time.Hour))
+	})
+
 	It("skips unknown parameters", func() {
 		b := &bytes.Buffer{}
 		// write a known parameter
diff --git a/internal/handshake/transport_parameters.go b/internal/handshake/transport_parameters.go
index 0c9928046..7f8da704a 100644
--- a/internal/handshake/transport_parameters.go
+++ b/internal/handshake/transport_parameters.go
@@ -139,6 +139,9 @@ func (p *TransportParameters) Unmarshal(data []byte, sentBy protocol.Perspective
 	if !readMaxAckDelay {
 		p.MaxAckDelay = protocol.DefaultMaxAckDelay
 	}
+	if p.MaxPacketSize == 0 {
+		p.MaxPacketSize = protocol.MaxByteCount
+	}
 
 	// check that every transport parameter was sent at most once
 	sort.Slice(parameterIDs, func(i, j int) bool { return parameterIDs[i] < parameterIDs[j] })
@@ -197,6 +200,9 @@ func (p *TransportParameters) readNumericTransportParameter(
 		if maxAckDelay >= protocol.MaxMaxAckDelay {
 			return fmt.Errorf("invalid value for max_ack_delay: %dms (maximum %dms)", maxAckDelay/time.Millisecond, (protocol.MaxMaxAckDelay-time.Millisecond)/time.Millisecond)
 		}
+		if maxAckDelay < 0 {
+			maxAckDelay = utils.InfDuration
+		}
 		p.MaxAckDelay = maxAckDelay
 	default:
 		return fmt.Errorf("TransportParameter BUG: transport parameter %d not found", paramID)
diff --git a/internal/wire/ack_frame.go b/internal/wire/ack_frame.go
index 65ab7008c..378ff6682 100644
--- a/internal/wire/ack_frame.go
+++ b/internal/wire/ack_frame.go
@@ -3,7 +3,6 @@ package wire
 import (
 	"bytes"
 	"errors"
-	"math"
 	"sort"
 	"time"
 
@@ -42,7 +41,7 @@ func parseAckFrame(r *bytes.Reader, ackDelayExponent uint8, version protocol.Ver
 	delayTime := time.Duration(delay*1<<ackDelayExponent) * time.Microsecond
 	if delayTime < 0 {
 		// If the delay time overflows, set it to the maximum encodable value.
-		delayTime = time.Duration(math.MaxInt64)
+		delayTime = utils.InfDuration
 	}
 	frame.DelayTime = delayTime