implement the max_datagram_frame_size transport parameter

internal/wire/transport_parameter_test.go

@@ -46,11 +46,12 @@ var _ = Describe("Transport Parameters", func() {
 			MaxAckDelay:                     37 * time.Millisecond,
 			StatelessResetToken:             &protocol.StatelessResetToken{0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, 0x00},
 			ActiveConnectionIDLimit:         123,
+			MaxDatagramFrameSize:            876,
 		}
-		Expect(p.String()).To(Equal("&wire.TransportParameters{OriginalDestinationConnectionID: 0xdeadbeef, InitialSourceConnectionID: 0xdecafbad, RetrySourceConnectionID: 0xdeadc0de, InitialMaxStreamDataBidiLocal: 1234, InitialMaxStreamDataBidiRemote: 2345, InitialMaxStreamDataUni: 3456, InitialMaxData: 4567, MaxBidiStreamNum: 1337, MaxUniStreamNum: 7331, MaxIdleTimeout: 42s, AckDelayExponent: 14, MaxAckDelay: 37ms, ActiveConnectionIDLimit: 123, StatelessResetToken: 0x112233445566778899aabbccddeeff00}"))
+		Expect(p.String()).To(Equal("&wire.TransportParameters{OriginalDestinationConnectionID: 0xdeadbeef, InitialSourceConnectionID: 0xdecafbad, RetrySourceConnectionID: 0xdeadc0de, InitialMaxStreamDataBidiLocal: 1234, InitialMaxStreamDataBidiRemote: 2345, InitialMaxStreamDataUni: 3456, InitialMaxData: 4567, MaxBidiStreamNum: 1337, MaxUniStreamNum: 7331, MaxIdleTimeout: 42s, AckDelayExponent: 14, MaxAckDelay: 37ms, ActiveConnectionIDLimit: 123, StatelessResetToken: 0x112233445566778899aabbccddeeff00, MaxDatagramFrameSize: 876}"))
 	})
 
-	It("has a string representation, if there's no stateless reset token and no Retry source connection id", func() {
+	It("has a string representation, if there's no stateless reset token, no Retry source connection id and no datagram support", func() {
 		p := &TransportParameters{
 			InitialMaxStreamDataBidiLocal:   1234,
 			InitialMaxStreamDataBidiRemote:  2345,
@@ -64,6 +65,7 @@ var _ = Describe("Transport Parameters", func() {
 			AckDelayExponent:                14,
 			MaxAckDelay:                     37 * time.Second,
 			ActiveConnectionIDLimit:         89,
+			MaxDatagramFrameSize:            protocol.InvalidByteCount,
 		}
 		Expect(p.String()).To(Equal("&wire.TransportParameters{OriginalDestinationConnectionID: 0xdeadbeef, InitialSourceConnectionID: (empty), InitialMaxStreamDataBidiLocal: 1234, InitialMaxStreamDataBidiRemote: 2345, InitialMaxStreamDataUni: 3456, InitialMaxData: 4567, MaxBidiStreamNum: 1337, MaxUniStreamNum: 7331, MaxIdleTimeout: 42s, AckDelayExponent: 14, MaxAckDelay: 37s, ActiveConnectionIDLimit: 89}"))
 	})
@@ -87,6 +89,7 @@ var _ = Describe("Transport Parameters", func() {
 			AckDelayExponent:                13,
 			MaxAckDelay:                     42 * time.Millisecond,
 			ActiveConnectionIDLimit:         getRandomValue(),
+			MaxDatagramFrameSize:            protocol.ByteCount(getRandomValue()),
 		}
 		data := params.Marshal(protocol.PerspectiveServer)
 
@@ -107,6 +110,7 @@ var _ = Describe("Transport Parameters", func() {
 		Expect(p.AckDelayExponent).To(Equal(uint8(13)))
 		Expect(p.MaxAckDelay).To(Equal(42 * time.Millisecond))
 		Expect(p.ActiveConnectionIDLimit).To(Equal(params.ActiveConnectionIDLimit))
+		Expect(p.MaxDatagramFrameSize).To(Equal(params.MaxDatagramFrameSize))
 	})
 
 	It("doesn't marshal a retry_source_connection_id, if no Retry was performed", func() {

internal/wire/transport_parameters.go

@@ -42,6 +42,8 @@ const (
 	activeConnectionIDLimitParameterID         transportParameterID = 0xe
 	initialSourceConnectionIDParameterID       transportParameterID = 0xf
 	retrySourceConnectionIDParameterID         transportParameterID = 0x10
+	// https://datatracker.ietf.org/doc/draft-ietf-quic-datagram/
+	maxDatagramFrameSizeParameterID transportParameterID = 0x20
 )
 
 // PreferredAddress is the value encoding in the preferred_address transport parameter
@@ -81,6 +83,8 @@ type TransportParameters struct {
 
 	StatelessResetToken     *protocol.StatelessResetToken
 	ActiveConnectionIDLimit uint64
+
+	MaxDatagramFrameSize protocol.ByteCount
 }
 
 // Unmarshal the transport parameters
@@ -96,12 +100,14 @@ func (p *TransportParameters) unmarshal(r *bytes.Reader, sentBy protocol.Perspec
 	var parameterIDs []transportParameterID
 
 	var (
-		readAckDelayExponent                bool
-		readMaxAckDelay                     bool
 		readOriginalDestinationConnectionID bool
 		readInitialSourceConnectionID       bool
 	)
 
+	p.AckDelayExponent = protocol.DefaultAckDelayExponent
+	p.MaxAckDelay = protocol.DefaultMaxAckDelay
+	p.MaxDatagramFrameSize = protocol.InvalidByteCount
+
 	for r.Len() > 0 {
 		paramIDInt, err := utils.ReadVarInt(r)
 		if err != nil {
@@ -118,12 +124,10 @@ func (p *TransportParameters) unmarshal(r *bytes.Reader, sentBy protocol.Perspec
 		parameterIDs = append(parameterIDs, paramID)
 		switch paramID {
 		case ackDelayExponentParameterID:
-			readAckDelayExponent = true
 			if err := p.readNumericTransportParameter(r, paramID, int(paramLen)); err != nil {
 				return err
 			}
 		case maxAckDelayParameterID:
-			readMaxAckDelay = true
 			if err := p.readNumericTransportParameter(r, paramID, int(paramLen)); err != nil {
 				return err
 			}
@@ -135,7 +139,8 @@ func (p *TransportParameters) unmarshal(r *bytes.Reader, sentBy protocol.Perspec
 			initialMaxStreamsUniParameterID,
 			maxIdleTimeoutParameterID,
 			maxUDPPayloadSizeParameterID,
-			activeConnectionIDLimitParameterID:
+			activeConnectionIDLimitParameterID,
+			maxDatagramFrameSizeParameterID:
 			if err := p.readNumericTransportParameter(r, paramID, int(paramLen)); err != nil {
 				return err
 			}
@@ -185,12 +190,6 @@ func (p *TransportParameters) unmarshal(r *bytes.Reader, sentBy protocol.Perspec
 		if sentBy == protocol.PerspectiveServer && !readOriginalDestinationConnectionID {
 			return errors.New("missing original_destination_connection_id")
 		}
-		if !readAckDelayExponent {
-			p.AckDelayExponent = protocol.DefaultAckDelayExponent
-		}
-		if !readMaxAckDelay {
-			p.MaxAckDelay = protocol.DefaultMaxAckDelay
-		}
 		if p.MaxUDPPayloadSize == 0 {
 			p.MaxUDPPayloadSize = protocol.MaxByteCount
 		}
@@ -305,6 +304,8 @@ func (p *TransportParameters) readNumericTransportParameter(
 		p.MaxAckDelay = maxAckDelay
 	case activeConnectionIDLimitParameterID:
 		p.ActiveConnectionIDLimit = val
+	case maxDatagramFrameSizeParameterID:
+		p.MaxDatagramFrameSize = protocol.ByteCount(val)
 	default:
 		return fmt.Errorf("TransportParameter BUG: transport parameter %d not found", paramID)
 	}
@@ -391,6 +392,9 @@ func (p *TransportParameters) Marshal(pers protocol.Perspective) []byte {
 		utils.WriteVarInt(b, uint64(p.RetrySourceConnectionID.Len()))
 		b.Write(p.RetrySourceConnectionID.Bytes())
 	}
+	if p.MaxDatagramFrameSize != protocol.InvalidByteCount {
+		p.marshalVarintParam(b, maxDatagramFrameSizeParameterID, uint64(p.MaxDatagramFrameSize))
+	}
 	return b.Bytes()
 }
 
@@ -463,6 +467,10 @@ func (p *TransportParameters) String() string {
 		logString += ", StatelessResetToken: %#x"
 		logParams = append(logParams, *p.StatelessResetToken)
 	}
+	if p.MaxDatagramFrameSize != protocol.InvalidByteCount {
+		logString += ", MaxDatagramFrameSize: %d"
+		logParams = append(logParams, p.MaxDatagramFrameSize)
+	}
 	logString += "}"
 	return fmt.Sprintf(logString, logParams...)
 }

session.go

@@ -294,6 +294,7 @@ var newSession = func(
 		ActiveConnectionIDLimit:         protocol.MaxActiveConnectionIDs,
 		InitialSourceConnectionID:       srcConnID,
 		RetrySourceConnectionID:         retrySrcConnID,
+		MaxDatagramFrameSize:            protocol.InvalidByteCount, // disable DATAGRAMs
 	}
 	if s.tracer != nil {
 		s.tracer.SentTransportParameters(params)
@@ -413,6 +414,7 @@ var newClientSession = func(
 		DisableActiveMigration:         true,
 		ActiveConnectionIDLimit:        protocol.MaxActiveConnectionIDs,
 		InitialSourceConnectionID:      srcConnID,
+		MaxDatagramFrameSize:           protocol.InvalidByteCount, // disable DATAGRAMs
 	}
 	if s.tracer != nil {
 		s.tracer.SentTransportParameters(params)