From 2c95141ee1fa80d37e4e21bd81e7c0a1de1e3ab4 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Wed, 27 Apr 2016 16:04:50 +0700
Subject: [PATCH] add Len() and ContainsPacketNumber() to NackRange

---
 ackhandler/sent_packet_handler.go |  4 ++--
 frames/ack_frame.go               | 10 ++------
 frames/nack_range.go              | 22 +++++++++++++++++
 frames/nack_range_test.go         | 39 +++++++++++++++++++++++++++++++
 4 files changed, 65 insertions(+), 10 deletions(-)
 create mode 100644 frames/nack_range.go
 create mode 100644 frames/nack_range_test.go

diff --git a/ackhandler/sent_packet_handler.go b/ackhandler/sent_packet_handler.go
index 55b481fc7..3e1400fb7 100644
--- a/ackhandler/sent_packet_handler.go
+++ b/ackhandler/sent_packet_handler.go
@@ -107,7 +107,7 @@ func (h *sentPacketHandler) calculateExpectedEntropy(ackFrame *frames.AckFrame)
 					nackRange = ackFrame.NackRanges[nackRangeIndex]
 				}
 			}
-			if i >= nackRange.FirstPacketNumber && i <= nackRange.LastPacketNumber {
+			if nackRange.ContainsPacketNumber(i) {
 				packet, ok := h.packetHistory[i]
 				if !ok {
 					return 0, ErrMapAccess
@@ -156,7 +156,7 @@ func (h *sentPacketHandler) ReceivedAck(ackFrame *frames.AckFrame) error {
 					nackRange = ackFrame.NackRanges[nackRangeIndex]
 				}
 			}
-			if i >= nackRange.FirstPacketNumber && i <= nackRange.LastPacketNumber {
+			if nackRange.ContainsPacketNumber(i) {
 				h.nackPacket(i)
 			} else {
 				h.ackPacket(i)
diff --git a/frames/ack_frame.go b/frames/ack_frame.go
index a01cd5f84..b5820a3ee 100644
--- a/frames/ack_frame.go
+++ b/frames/ack_frame.go
@@ -8,12 +8,6 @@ import (
 	"github.com/lucas-clemente/quic-go/utils"
 )
 
-// NackRange is a NACK range
-type NackRange struct {
-	FirstPacketNumber protocol.PacketNumber
-	LastPacketNumber  protocol.PacketNumber
-}
-
 var errInvalidNackRanges = errors.New("AckFrame: ACK frame contains invalid NACK ranges")
 
 // An AckFrame in QUIC
@@ -45,7 +39,7 @@ func (f *AckFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, pa
 		// calculate the number of NackRanges that are about to be written
 		// this number is different from len(f.NackRanges) for the case of contiguous NACK ranges
 		for _, nackRange := range f.NackRanges {
-			rangeLength := uint64(nackRange.LastPacketNumber - nackRange.FirstPacketNumber)
+			rangeLength := nackRange.Len()
 			numRanges += rangeLength/0xFF + 1
 			if rangeLength > 0 && rangeLength%0xFF == 0 {
 				numRanges--
@@ -69,7 +63,7 @@ func (f *AckFrame) Write(b *bytes.Buffer, packetNumber protocol.PacketNumber, pa
 				lastNackRange := f.NackRanges[i-1]
 				missingPacketSequenceNumberDelta = uint64(lastNackRange.FirstPacketNumber) - uint64(nackRange.LastPacketNumber) - 1
 			}
-			rangeLength := nackRange.LastPacketNumber - nackRange.FirstPacketNumber
+			rangeLength := nackRange.Len()
 
 			utils.WriteUint48(b, missingPacketSequenceNumberDelta)
 			b.WriteByte(uint8(rangeLength % 0x100))
diff --git a/frames/nack_range.go b/frames/nack_range.go
new file mode 100644
index 000000000..455478df4
--- /dev/null
+++ b/frames/nack_range.go
@@ -0,0 +1,22 @@
+package frames
+
+import "github.com/lucas-clemente/quic-go/protocol"
+
+// NackRange is a NACK range
+type NackRange struct {
+	FirstPacketNumber protocol.PacketNumber
+	LastPacketNumber  protocol.PacketNumber
+}
+
+// Len gets the lengths of a NackRange
+func (n *NackRange) Len() uint64 {
+	return uint64(n.LastPacketNumber) - uint64(n.FirstPacketNumber)
+}
+
+// IsInRange checks if a packetNumber is contained in a NACK range
+func (n *NackRange) ContainsPacketNumber(packetNumber protocol.PacketNumber) bool {
+	if packetNumber >= n.FirstPacketNumber && packetNumber <= n.LastPacketNumber {
+		return true
+	}
+	return false
+}
diff --git a/frames/nack_range_test.go b/frames/nack_range_test.go
new file mode 100644
index 000000000..5a5d09bc5
--- /dev/null
+++ b/frames/nack_range_test.go
@@ -0,0 +1,39 @@
+package frames
+
+import (
+	"github.com/lucas-clemente/quic-go/protocol"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("NackRange", func() {
+	Context("Length", func() {
+		It("calculates the length for a NACK range with only one packet", func() {
+			nackRange := NackRange{FirstPacketNumber: 2, LastPacketNumber: 2}
+			Expect(nackRange.Len()).To(Equal(uint64(0)))
+		})
+
+		It("calculates the length for a NACK range with more than one packet", func() {
+			nackRange := NackRange{FirstPacketNumber: 10, LastPacketNumber: 20}
+			Expect(nackRange.Len()).To(Equal(uint64(10)))
+		})
+	})
+
+	Context("ContainsPacketNumber", func() {
+		It("determines if a packet is in a NACK range with only one packet", func() {
+			nackRange := NackRange{FirstPacketNumber: 2, LastPacketNumber: 2}
+			Expect(nackRange.ContainsPacketNumber(protocol.PacketNumber(1))).To(BeFalse())
+			Expect(nackRange.ContainsPacketNumber(protocol.PacketNumber(3))).To(BeFalse())
+			Expect(nackRange.ContainsPacketNumber(protocol.PacketNumber(2))).To(BeTrue())
+		})
+
+		It("determines if a packet is in a NACK range with more than one packet", func() {
+			nackRange := NackRange{FirstPacketNumber: 10, LastPacketNumber: 20}
+			Expect(nackRange.ContainsPacketNumber(protocol.PacketNumber(1))).To(BeFalse())
+			Expect(nackRange.ContainsPacketNumber(protocol.PacketNumber(10))).To(BeTrue())
+			Expect(nackRange.ContainsPacketNumber(protocol.PacketNumber(15))).To(BeTrue())
+			Expect(nackRange.ContainsPacketNumber(protocol.PacketNumber(20))).To(BeTrue())
+			Expect(nackRange.ContainsPacketNumber(protocol.PacketNumber(21))).To(BeFalse())
+		})
+	})
+})