From 3d087d522ca3c23def68fd362ec216408fe2210c Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Sat, 14 Jul 2018 21:34:08 +0200
Subject: [PATCH] implement parsing of ACK_ECN frames

---
 .gometalinter.json                 |  3 ++-
 internal/wire/ack_frame.go         | 19 +++++++++++++-
 internal/wire/ack_frame_test.go    | 42 ++++++++++++++++++++++++++++++
 internal/wire/frame_parser.go      |  5 ++++
 internal/wire/frame_parser_test.go |  1 +
 5 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/.gometalinter.json b/.gometalinter.json
index 4c9ed3cd..808b0344 100644
--- a/.gometalinter.json
+++ b/.gometalinter.json
@@ -17,6 +17,7 @@
     "vet"
   ],
   "Linters": {
-    "vet": "go tool vet -printfuncs=Infof,Debugf,Warningf,Errorf:PATH:LINE:MESSAGE"
+    "vet": "go tool vet -printfuncs=Infof,Debugf,Warningf,Errorf:PATH:LINE:MESSAGE",
+    "misspell": "misspell -i ect:PATH:LINE:COL:MESSAGE"
   }
 }
diff --git a/internal/wire/ack_frame.go b/internal/wire/ack_frame.go
index 021cef53..00759db4 100644
--- a/internal/wire/ack_frame.go
+++ b/internal/wire/ack_frame.go
@@ -19,8 +19,16 @@ type AckFrame struct {
 	DelayTime time.Duration
 }
 
-// parseAckFrame reads an ACK frame
 func parseAckFrame(r *bytes.Reader, version protocol.VersionNumber) (*AckFrame, error) {
+	return parseAckOrAckEcnFrame(r, false, version)
+}
+
+func parseAckEcnFrame(r *bytes.Reader, version protocol.VersionNumber) (*AckFrame, error) {
+	return parseAckOrAckEcnFrame(r, true, version)
+}
+
+// parseAckFrame reads an ACK frame
+func parseAckOrAckEcnFrame(r *bytes.Reader, ecn bool, version protocol.VersionNumber) (*AckFrame, error) {
 	if !version.UsesIETFFrameFormat() {
 		return parseAckFrameLegacy(r, version)
 	}
@@ -41,6 +49,15 @@ func parseAckFrame(r *bytes.Reader, version protocol.VersionNumber) (*AckFrame,
 		return nil, err
 	}
 	frame.DelayTime = time.Duration(delay*1<<ackDelayExponent) * time.Microsecond
+
+	if ecn {
+		for i := 0; i < 3; i++ {
+			if _, err := utils.ReadVarInt(r); err != nil {
+				return nil, err
+			}
+		}
+	}
+
 	numBlocks, err := utils.ReadVarInt(r)
 	if err != nil {
 		return nil, err
diff --git a/internal/wire/ack_frame_test.go b/internal/wire/ack_frame_test.go
index a4df8b24..65c9e4ab 100644
--- a/internal/wire/ack_frame_test.go
+++ b/internal/wire/ack_frame_test.go
@@ -366,3 +366,45 @@ var _ = Describe("ACK Frame (for IETF QUIC)", func() {
 		})
 	})
 })
+
+var _ = Describe("ACK_ECN frame", func() {
+	Context("parsing", func() {
+		It("parses an ACK_ECN frame", func() {
+			data := []byte{0xd}
+			data = append(data, encodeVarInt(100)...)        // largest acked
+			data = append(data, encodeVarInt(0)...)          // delay
+			data = append(data, encodeVarInt(0x42)...)       // ECT(0)
+			data = append(data, encodeVarInt(0x12345)...)    // ECT(1)
+			data = append(data, encodeVarInt(0x12345678)...) // ECN-CE
+			data = append(data, encodeVarInt(0)...)          // num blocks
+			data = append(data, encodeVarInt(10)...)         // first ack block
+			b := bytes.NewReader(data)
+			frame, err := parseAckEcnFrame(b, versionIETFFrames)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(frame.LargestAcked()).To(Equal(protocol.PacketNumber(100)))
+			Expect(frame.LowestAcked()).To(Equal(protocol.PacketNumber(90)))
+			Expect(frame.HasMissingRanges()).To(BeFalse())
+			Expect(b.Len()).To(BeZero())
+		})
+
+		It("errors on EOF", func() {
+			data := []byte{0x1a}
+			data = append(data, encodeVarInt(1000)...)       // largest acked
+			data = append(data, encodeVarInt(0)...)          // delay
+			data = append(data, encodeVarInt(0x42)...)       // ECT(0)
+			data = append(data, encodeVarInt(0x12345)...)    // ECT(1)
+			data = append(data, encodeVarInt(0x12345678)...) // ECN-CE
+			data = append(data, encodeVarInt(1)...)          // num blocks
+			data = append(data, encodeVarInt(100)...)        // first ack block
+			data = append(data, encodeVarInt(98)...)         // gap
+			data = append(data, encodeVarInt(50)...)         // ack block
+			_, err := parseAckEcnFrame(bytes.NewReader(data), versionIETFFrames)
+			Expect(err).NotTo(HaveOccurred())
+			for i := range data {
+				_, err := parseAckEcnFrame(bytes.NewReader(data[0:i]), versionIETFFrames)
+				Expect(err).To(MatchError(io.EOF))
+			}
+		})
+
+	})
+})
diff --git a/internal/wire/frame_parser.go b/internal/wire/frame_parser.go
index 67b191b4..00abf4bf 100644
--- a/internal/wire/frame_parser.go
+++ b/internal/wire/frame_parser.go
@@ -100,6 +100,11 @@ func parseIETFFrame(r *bytes.Reader, typeByte byte, v protocol.VersionNumber) (F
 		if err != nil {
 			err = qerr.Error(qerr.InvalidFrameData, err.Error())
 		}
+	case 0x1a:
+		frame, err = parseAckEcnFrame(r, v)
+		if err != nil {
+			err = qerr.Error(qerr.InvalidAckData, err.Error())
+		}
 	default:
 		err = qerr.Error(qerr.InvalidFrameData, fmt.Sprintf("unknown type byte 0x%x", typeByte))
 	}
diff --git a/internal/wire/frame_parser_test.go b/internal/wire/frame_parser_test.go
index 525589e9..1b9d4068 100644
--- a/internal/wire/frame_parser_test.go
+++ b/internal/wire/frame_parser_test.go
@@ -331,6 +331,7 @@ var _ = Describe("Frame parsing", func() {
 				0x0e: qerr.InvalidFrameData,
 				0x0f: qerr.InvalidFrameData,
 				0x10: qerr.InvalidStreamData,
+				0x1a: qerr.InvalidAckData,
 			} {
 				_, err := ParseNextFrame(bytes.NewReader([]byte{b}), nil, versionIETFFrames)
 				Expect(err).To(HaveOccurred())