save the max_datagram_frame_size transport parameter in the session ticket (#4013)

* Add MaxDatagramFrameSize parameter in session ticket

* fix gofumpt issues

* Update integrationtests/self/zero_rtt_test.go

Co-authored-by: Marten Seemann <martenseemann@gmail.com>

* fix: correct comparsion of max_datagram_frame_size

* test: use constant MaxDatagramFrameSize for session ticket test

* fix grammar

---------

Co-authored-by: Marten Seemann <martenseemann@gmail.com>

integrationtests/self/zero_rtt_oldgo_test.go

@@ -801,4 +801,116 @@ var _ = Describe("0-RTT", func() {
 		Expect(len(zeroRTTPackets)).To(BeNumerically(">", 10))
 		Expect(zeroRTTPackets[0]).To(Equal(protocol.PacketNumber(0)))
 	})
+
+	It("sends 0-RTT datagrams", func() {
+		tlsConf, clientTLSConf := dialAndReceiveSessionTicket(getQuicConfig(&quic.Config{
+			EnableDatagrams: true,
+		}))
+
+		tracer := newPacketTracer()
+		ln, err := quic.ListenAddrEarly(
+			"localhost:0",
+			tlsConf,
+			getQuicConfig(&quic.Config{
+				Allow0RTT:       true,
+				EnableDatagrams: true,
+				Tracer:          newTracer(tracer),
+			}),
+		)
+		Expect(err).ToNot(HaveOccurred())
+		defer ln.Close()
+
+		proxy, num0RTTPackets := runCountingProxy(ln.Addr().(*net.UDPAddr).Port)
+		defer proxy.Close()
+
+		// second connection
+		sentMessage := GeneratePRData(100)
+		var receivedMessage []byte
+		received := make(chan struct{})
+		go func() {
+			defer GinkgoRecover()
+			defer close(received)
+			conn, err := ln.Accept(context.Background())
+			Expect(err).ToNot(HaveOccurred())
+			receivedMessage, err = conn.ReceiveMessage(context.Background())
+			Expect(err).ToNot(HaveOccurred())
+			Expect(conn.ConnectionState().Used0RTT).To(BeTrue())
+		}()
+		conn, err := quic.DialAddrEarly(
+			context.Background(),
+			fmt.Sprintf("localhost:%d", proxy.LocalPort()),
+			clientTLSConf,
+			getQuicConfig(&quic.Config{
+				EnableDatagrams: true,
+			}),
+		)
+		Expect(err).ToNot(HaveOccurred())
+		Expect(conn.ConnectionState().SupportsDatagrams).To(BeTrue())
+		Expect(conn.SendMessage(sentMessage)).To(Succeed())
+		<-conn.HandshakeComplete()
+		<-received
+
+		Expect(conn.ConnectionState().Used0RTT).To(BeTrue())
+		Expect(receivedMessage).To(Equal(sentMessage))
+		num0RTT := atomic.LoadUint32(num0RTTPackets)
+		fmt.Fprintf(GinkgoWriter, "Sent %d 0-RTT packets.", num0RTT)
+		Expect(num0RTT).ToNot(BeZero())
+		zeroRTTPackets := get0RTTPackets(tracer.getRcvdLongHeaderPackets())
+		Expect(zeroRTTPackets).To(HaveLen(1))
+		Expect(conn.CloseWithError(0, "")).To(Succeed())
+	})
+
+	It("rejects 0-RTT datagrams when the server doesn't support datagrams anymore", func() {
+		tlsConf, clientTLSConf := dialAndReceiveSessionTicket(getQuicConfig(&quic.Config{
+			EnableDatagrams: true,
+		}))
+
+		tracer := newPacketTracer()
+		ln, err := quic.ListenAddrEarly(
+			"localhost:0",
+			tlsConf,
+			getQuicConfig(&quic.Config{
+				Allow0RTT:       true,
+				EnableDatagrams: false,
+				Tracer:          newTracer(tracer),
+			}),
+		)
+		Expect(err).ToNot(HaveOccurred())
+		defer ln.Close()
+
+		proxy, num0RTTPackets := runCountingProxy(ln.Addr().(*net.UDPAddr).Port)
+		defer proxy.Close()
+
+		// second connection
+		go func() {
+			defer GinkgoRecover()
+			conn, err := ln.Accept(context.Background())
+			Expect(err).ToNot(HaveOccurred())
+			_, err = conn.ReceiveMessage(context.Background())
+			Expect(err.Error()).To(Equal("datagram support disabled"))
+			<-conn.HandshakeComplete()
+			Expect(conn.ConnectionState().Used0RTT).To(BeFalse())
+		}()
+		conn, err := quic.DialAddrEarly(
+			context.Background(),
+			fmt.Sprintf("localhost:%d", proxy.LocalPort()),
+			clientTLSConf,
+			getQuicConfig(&quic.Config{
+				EnableDatagrams: true,
+			}),
+		)
+		Expect(err).ToNot(HaveOccurred())
+		// the client can temporarily send datagrams but the server doesn't process them.
+		Expect(conn.ConnectionState().SupportsDatagrams).To(BeTrue())
+		Expect(conn.SendMessage(make([]byte, 100))).To(Succeed())
+		<-conn.HandshakeComplete()
+
+		Expect(conn.ConnectionState().SupportsDatagrams).To(BeFalse())
+		Expect(conn.ConnectionState().Used0RTT).To(BeFalse())
+		num0RTT := atomic.LoadUint32(num0RTTPackets)
+		fmt.Fprintf(GinkgoWriter, "Sent %d 0-RTT packets.", num0RTT)
+		Expect(num0RTT).ToNot(BeZero())
+		Expect(get0RTTPackets(tracer.getRcvdLongHeaderPackets())).To(BeEmpty())
+		Expect(conn.CloseWithError(0, "")).To(Succeed())
+	})
 })

integrationtests/self/zero_rtt_test.go

@@ -938,4 +938,119 @@ var _ = Describe("0-RTT", func() {
 		)
 		Expect(restored).To(BeTrue())
 	})
+
+	It("sends 0-RTT datagrams", func() {
+		tlsConf := getTLSConfig()
+		clientTLSConf := getTLSClientConfig()
+		dialAndReceiveSessionTicket(tlsConf, getQuicConfig(&quic.Config{
+			EnableDatagrams: true,
+		}), clientTLSConf)
+
+		tracer := newPacketTracer()
+		ln, err := quic.ListenAddrEarly(
+			"localhost:0",
+			tlsConf,
+			getQuicConfig(&quic.Config{
+				Allow0RTT:       true,
+				EnableDatagrams: true,
+				Tracer:          newTracer(tracer),
+			}),
+		)
+		Expect(err).ToNot(HaveOccurred())
+		defer ln.Close()
+		proxy, num0RTTPackets := runCountingProxy(ln.Addr().(*net.UDPAddr).Port)
+		defer proxy.Close()
+
+		// second connection
+		sentMessage := GeneratePRData(100)
+		var receivedMessage []byte
+		received := make(chan struct{})
+		go func() {
+			defer GinkgoRecover()
+			defer close(received)
+			conn, err := ln.Accept(context.Background())
+			Expect(err).ToNot(HaveOccurred())
+			receivedMessage, err = conn.ReceiveMessage(context.Background())
+			Expect(err).ToNot(HaveOccurred())
+			Expect(conn.ConnectionState().Used0RTT).To(BeTrue())
+		}()
+		conn, err := quic.DialAddrEarly(
+			context.Background(),
+			fmt.Sprintf("localhost:%d", proxy.LocalPort()),
+			clientTLSConf,
+			getQuicConfig(&quic.Config{
+				EnableDatagrams: true,
+			}),
+		)
+		Expect(err).ToNot(HaveOccurred())
+		Expect(conn.ConnectionState().SupportsDatagrams).To(BeTrue())
+		Expect(conn.SendMessage(sentMessage)).To(Succeed())
+		<-conn.HandshakeComplete()
+		<-received
+
+		Expect(conn.ConnectionState().Used0RTT).To(BeTrue())
+		Expect(receivedMessage).To(Equal(sentMessage))
+		num0RTT := atomic.LoadUint32(num0RTTPackets)
+		fmt.Fprintf(GinkgoWriter, "Sent %d 0-RTT packets.", num0RTT)
+		Expect(num0RTT).ToNot(BeZero())
+		zeroRTTPackets := get0RTTPackets(tracer.getRcvdLongHeaderPackets())
+		Expect(zeroRTTPackets).To(HaveLen(1))
+		Expect(conn.CloseWithError(0, "")).To(Succeed())
+	})
+
+	It("rejects 0-RTT datagrams when the server doesn't support datagrams anymore", func() {
+		tlsConf := getTLSConfig()
+		clientTLSConf := getTLSClientConfig()
+		dialAndReceiveSessionTicket(tlsConf, getQuicConfig(&quic.Config{
+			EnableDatagrams: true,
+		}), clientTLSConf)
+
+		tracer := newPacketTracer()
+		ln, err := quic.ListenAddrEarly(
+			"localhost:0",
+			tlsConf,
+			getQuicConfig(&quic.Config{
+				Allow0RTT:       true,
+				EnableDatagrams: false,
+				Tracer:          newTracer(tracer),
+			}),
+		)
+		Expect(err).ToNot(HaveOccurred())
+		defer ln.Close()
+
+		proxy, num0RTTPackets := runCountingProxy(ln.Addr().(*net.UDPAddr).Port)
+		defer proxy.Close()
+
+		// second connection
+		go func() {
+			defer GinkgoRecover()
+			conn, err := ln.Accept(context.Background())
+			Expect(err).ToNot(HaveOccurred())
+			_, err = conn.ReceiveMessage(context.Background())
+			Expect(err.Error()).To(Equal("datagram support disabled"))
+			<-conn.HandshakeComplete()
+			Expect(conn.ConnectionState().Used0RTT).To(BeFalse())
+		}()
+		conn, err := quic.DialAddrEarly(
+			context.Background(),
+			fmt.Sprintf("localhost:%d", proxy.LocalPort()),
+			clientTLSConf,
+			getQuicConfig(&quic.Config{
+				EnableDatagrams: true,
+			}),
+		)
+		Expect(err).ToNot(HaveOccurred())
+		// the client can temporarily send datagrams but the server doesn't process them.
+		Expect(conn.ConnectionState().SupportsDatagrams).To(BeTrue())
+		Expect(conn.SendMessage(make([]byte, 100))).To(Succeed())
+		<-conn.HandshakeComplete()
+
+		Expect(conn.ConnectionState().SupportsDatagrams).To(BeFalse())
+		Expect(conn.ConnectionState().Used0RTT).To(BeFalse())
+		num0RTT := atomic.LoadUint32(num0RTTPackets)
+		fmt.Fprintf(GinkgoWriter, "Sent %d 0-RTT packets.", num0RTT)
+		Expect(num0RTT).ToNot(BeZero())
+		Expect(get0RTTPackets(tracer.getRcvdLongHeaderPackets())).To(BeEmpty())
+		Expect(conn.CloseWithError(0, "")).To(Succeed())
+	})
 })

internal/handshake/session_ticket_test.go

@@ -17,6 +17,7 @@ var _ = Describe("Session Ticket", func() {
 				InitialMaxStreamDataBidiLocal:  1,
 				InitialMaxStreamDataBidiRemote: 2,
 				ActiveConnectionIDLimit:        10,
+				MaxDatagramFrameSize:           20,
 			},
 			RTT: 1337 * time.Microsecond,
 		}
@@ -25,6 +26,7 @@ var _ = Describe("Session Ticket", func() {
 		Expect(t.Parameters.InitialMaxStreamDataBidiLocal).To(BeEquivalentTo(1))
 		Expect(t.Parameters.InitialMaxStreamDataBidiRemote).To(BeEquivalentTo(2))
 		Expect(t.Parameters.ActiveConnectionIDLimit).To(BeEquivalentTo(10))
+		Expect(t.Parameters.MaxDatagramFrameSize).To(BeEquivalentTo(20))
 		Expect(t.RTT).To(Equal(1337 * time.Microsecond))
 	})
 

internal/wire/transport_parameter_test.go

@@ -503,6 +503,7 @@ var _ = Describe("Transport Parameters", func() {
 				MaxBidiStreamNum:               protocol.StreamNum(getRandomValueUpTo(int64(protocol.MaxStreamCount))),
 				MaxUniStreamNum:                protocol.StreamNum(getRandomValueUpTo(int64(protocol.MaxStreamCount))),
 				ActiveConnectionIDLimit:        2 + getRandomValueUpTo(math.MaxInt64-2),
+				MaxDatagramFrameSize:           protocol.ByteCount(getRandomValueUpTo(int64(protocol.MaxDatagramFrameSize))),
 			}
 			Expect(params.ValidFor0RTT(params)).To(BeTrue())
 			b := params.MarshalForSessionTicket(nil)
@@ -515,6 +516,7 @@ var _ = Describe("Transport Parameters", func() {
 			Expect(tp.MaxBidiStreamNum).To(Equal(params.MaxBidiStreamNum))
 			Expect(tp.MaxUniStreamNum).To(Equal(params.MaxUniStreamNum))
 			Expect(tp.ActiveConnectionIDLimit).To(Equal(params.ActiveConnectionIDLimit))
+			Expect(tp.MaxDatagramFrameSize).To(Equal(params.MaxDatagramFrameSize))
 		})
 
 		It("rejects the parameters if it can't parse them", func() {
@@ -540,6 +542,7 @@ var _ = Describe("Transport Parameters", func() {
 				MaxBidiStreamNum:               5,
 				MaxUniStreamNum:                6,
 				ActiveConnectionIDLimit:        7,
+				MaxDatagramFrameSize:           1000,
 			}
 
 			BeforeEach(func() {
@@ -611,6 +614,16 @@ var _ = Describe("Transport Parameters", func() {
 				p.ActiveConnectionIDLimit = 0
 				Expect(p.ValidFor0RTT(saved)).To(BeFalse())
 			})
+
+			It("accepts the parameters if the MaxDatagramFrameSize was increased", func() {
+				p.MaxDatagramFrameSize = saved.MaxDatagramFrameSize + 1
+				Expect(p.ValidFor0RTT(saved)).To(BeTrue())
+			})
+
+			It("rejects the parameters if the MaxDatagramFrameSize reduced", func() {
+				p.MaxDatagramFrameSize = saved.MaxDatagramFrameSize - 1
+				Expect(p.ValidFor0RTT(saved)).To(BeFalse())
+			})
 		})
 
 		Context("client checks the parameters after successfully sending 0-RTT data", func() {
@@ -623,6 +636,7 @@ var _ = Describe("Transport Parameters", func() {
 				MaxBidiStreamNum:               5,
 				MaxUniStreamNum:                6,
 				ActiveConnectionIDLimit:        7,
+				MaxDatagramFrameSize:           1000,
 			}
 
 			BeforeEach(func() {
@@ -699,6 +713,16 @@ var _ = Describe("Transport Parameters", func() {
 				p.ActiveConnectionIDLimit = saved.ActiveConnectionIDLimit + 1
 				Expect(p.ValidForUpdate(saved)).To(BeTrue())
 			})
+
+			It("rejects the parameters if the MaxDatagramFrameSize reduced", func() {
+				p.MaxDatagramFrameSize = saved.MaxDatagramFrameSize - 1
+				Expect(p.ValidForUpdate(saved)).To(BeFalse())
+			})
+
+			It("doesn't reject the parameters if the MaxDatagramFrameSize increased", func() {
+				p.MaxDatagramFrameSize = saved.MaxDatagramFrameSize + 1
+				Expect(p.ValidForUpdate(saved)).To(BeTrue())
+			})
 		})
 	})
 })

internal/wire/transport_parameters.go

@@ -454,6 +454,10 @@ func (p *TransportParameters) MarshalForSessionTicket(b []byte) []byte {
 	b = p.marshalVarintParam(b, initialMaxStreamsBidiParameterID, uint64(p.MaxBidiStreamNum))
 	// initial_max_uni_streams
 	b = p.marshalVarintParam(b, initialMaxStreamsUniParameterID, uint64(p.MaxUniStreamNum))
+	// max_datagram_frame_size
+	if p.MaxDatagramFrameSize != protocol.InvalidByteCount {
+		b = p.marshalVarintParam(b, maxDatagramFrameSizeParameterID, uint64(p.MaxDatagramFrameSize))
+	}
 	// active_connection_id_limit
 	return p.marshalVarintParam(b, activeConnectionIDLimitParameterID, p.ActiveConnectionIDLimit)
 }
@@ -472,6 +476,9 @@ func (p *TransportParameters) UnmarshalFromSessionTicket(r *bytes.Reader) error
 
 // ValidFor0RTT checks if the transport parameters match those saved in the session ticket.
 func (p *TransportParameters) ValidFor0RTT(saved *TransportParameters) bool {
+	if saved.MaxDatagramFrameSize != protocol.InvalidByteCount && (p.MaxDatagramFrameSize == protocol.InvalidByteCount || p.MaxDatagramFrameSize < saved.MaxDatagramFrameSize) {
+		return false
+	}
 	return p.InitialMaxStreamDataBidiLocal >= saved.InitialMaxStreamDataBidiLocal &&
 		p.InitialMaxStreamDataBidiRemote >= saved.InitialMaxStreamDataBidiRemote &&
 		p.InitialMaxStreamDataUni >= saved.InitialMaxStreamDataUni &&
@@ -484,6 +491,9 @@ func (p *TransportParameters) ValidFor0RTT(saved *TransportParameters) bool {
 // ValidForUpdate checks that the new transport parameters don't reduce limits after resuming a 0-RTT connection.
 // It is only used on the client side.
 func (p *TransportParameters) ValidForUpdate(saved *TransportParameters) bool {
+	if saved.MaxDatagramFrameSize != protocol.InvalidByteCount && (p.MaxDatagramFrameSize == protocol.InvalidByteCount || p.MaxDatagramFrameSize < saved.MaxDatagramFrameSize) {
+		return false
+	}
 	return p.ActiveConnectionIDLimit >= saved.ActiveConnectionIDLimit &&
 		p.InitialMaxData >= saved.InitialMaxData &&
 		p.InitialMaxStreamDataBidiLocal >= saved.InitialMaxStreamDataBidiLocal &&