Internal change.

PiperOrigin-RevId: 274700093

11 files changed, 295 insertions, 51 deletions

diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index d0cfdcda1..3187b336b 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -422,7 +422,10 @@ func send4(r *stack.Route, ident uint16, data buffer.View, ttl uint8) *tcpip.Err
 	icmpv4.SetChecksum(0)
 	icmpv4.SetChecksum(^header.Checksum(icmpv4, header.Checksum(data, 0)))
 
-	return r.WritePacket(nil /* gso */, hdr, data.ToVectorisedView(), header.ICMPv4ProtocolNumber, ttl, ttl == 0 /* useDefaultTTL */)
+	if ttl == 0 {
+		ttl = r.DefaultTTL()
+	}
+	return r.WritePacket(nil /* gso */, hdr, data.ToVectorisedView(), stack.NetworkHeaderParams{Protocol: header.ICMPv4ProtocolNumber, TTL: ttl, TOS: stack.DefaultTOS})
 }
 
 func send6(r *stack.Route, ident uint16, data buffer.View, ttl uint8) *tcpip.Error {
@@ -445,7 +448,10 @@ func send6(r *stack.Route, ident uint16, data buffer.View, ttl uint8) *tcpip.Err
 	icmpv6.SetChecksum(0)
 	icmpv6.SetChecksum(^header.Checksum(icmpv6, header.Checksum(data, 0)))
 
-	return r.WritePacket(nil /* gso */, hdr, data.ToVectorisedView(), header.ICMPv6ProtocolNumber, ttl, ttl == 0 /* useDefaultTTL */)
+	if ttl == 0 {
+		ttl = r.DefaultTTL()
+	}
+	return r.WritePacket(nil /* gso */, hdr, data.ToVectorisedView(), stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: ttl, TOS: stack.DefaultTOS})
 }
 
 func (e *endpoint) checkV4Mapped(addr *tcpip.FullAddress, allowMismatch bool) (tcpip.NetworkProtocolNumber, *tcpip.Error) {
diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
index 4f5c286cf..b4c660859 100644
--- a/pkg/tcpip/transport/raw/endpoint.go
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -350,7 +350,7 @@ func (e *endpoint) finishWrite(payloadBytes []byte, route *stack.Route) (int64,
 			break
 		}
 		hdr := buffer.NewPrependable(len(payloadBytes) + int(route.MaxHeaderLength()))
-		if err := route.WritePacket(nil /* gso */, hdr, buffer.View(payloadBytes).ToVectorisedView(), e.TransProto, 0, true /* useDefaultTTL */); err != nil {
+		if err := route.WritePacket(nil /* gso */, hdr, buffer.View(payloadBytes).ToVectorisedView(), stack.NetworkHeaderParams{Protocol: e.TransProto, TTL: route.DefaultTTL(), TOS: stack.DefaultTOS}); err != nil {
 			return 0, nil, err
 		}
 
diff --git a/pkg/tcpip/transport/tcp/accept.go b/pkg/tcpip/transport/tcp/accept.go
index 8f5572195..844959fa0 100644
--- a/pkg/tcpip/transport/tcp/accept.go
+++ b/pkg/tcpip/transport/tcp/accept.go
@@ -441,7 +441,7 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) {
 				TSEcr: opts.TSVal,
 				MSS:   uint16(mss),
 			}
-			e.sendSynTCP(&s.route, s.id, e.ttl, header.TCPFlagSyn|header.TCPFlagAck, cookie, s.sequenceNumber+1, ctx.rcvWnd, synOpts)
+			e.sendSynTCP(&s.route, s.id, e.ttl, e.sendTOS, header.TCPFlagSyn|header.TCPFlagAck, cookie, s.sequenceNumber+1, ctx.rcvWnd, synOpts)
 			e.stack.Stats().TCP.ListenOverflowSynCookieSent.Increment()
 		}
 
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index cb8cfd619..5ea036bea 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -255,7 +255,7 @@ func (h *handshake) synSentState(s *segment) *tcpip.Error {
 	if ttl == 0 {
 		ttl = s.route.DefaultTTL()
 	}
-	h.ep.sendSynTCP(&s.route, h.ep.ID, ttl, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts)
+	h.ep.sendSynTCP(&s.route, h.ep.ID, ttl, h.ep.sendTOS, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts)
 	return nil
 }
 
@@ -299,7 +299,7 @@ func (h *handshake) synRcvdState(s *segment) *tcpip.Error {
 			SACKPermitted: h.ep.sackPermitted,
 			MSS:           h.ep.amss,
 		}
-		h.ep.sendSynTCP(&s.route, h.ep.ID, h.ep.ttl, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts)
+		h.ep.sendSynTCP(&s.route, h.ep.ID, h.ep.ttl, h.ep.sendTOS, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts)
 		return nil
 	}
 
@@ -468,7 +468,8 @@ func (h *handshake) execute() *tcpip.Error {
 			synOpts.WS = -1
 		}
 	}
-	h.ep.sendSynTCP(&h.ep.route, h.ep.ID, h.ep.ttl, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts)
+	h.ep.sendSynTCP(&h.ep.route, h.ep.ID, h.ep.ttl, h.ep.sendTOS, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts)
+
 	for h.state != handshakeCompleted {
 		switch index, _ := s.Fetch(true); index {
 		case wakerForResend:
@@ -477,7 +478,7 @@ func (h *handshake) execute() *tcpip.Error {
 				return tcpip.ErrTimeout
 			}
 			rt.Reset(timeOut)
-			h.ep.sendSynTCP(&h.ep.route, h.ep.ID, h.ep.ttl, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts)
+			h.ep.sendSynTCP(&h.ep.route, h.ep.ID, h.ep.ttl, h.ep.sendTOS, h.flags, h.iss, h.ackNum, h.rcvWnd, synOpts)
 
 		case wakerForNotification:
 			n := h.ep.fetchNotifications()
@@ -587,17 +588,18 @@ func makeSynOptions(opts header.TCPSynOptions) []byte {
 	return options[:offset]
 }
 
-func (e *endpoint) sendSynTCP(r *stack.Route, id stack.TransportEndpointID, ttl uint8, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size, opts header.TCPSynOptions) {
+func (e *endpoint) sendSynTCP(r *stack.Route, id stack.TransportEndpointID, ttl, tos uint8, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size, opts header.TCPSynOptions) *tcpip.Error {
 	options := makeSynOptions(opts)
 	// We ignore SYN send errors and let the callers re-attempt send.
-	if err := e.sendTCP(r, id, buffer.VectorisedView{}, ttl, flags, seq, ack, rcvWnd, options, nil); err != nil {
+	if err := e.sendTCP(r, id, buffer.VectorisedView{}, ttl, tos, flags, seq, ack, rcvWnd, options, nil); err != nil {
 		e.stats.SendErrors.SynSendToNetworkFailed.Increment()
 	}
 	putOptions(options)
+	return nil
 }
 
-func (e *endpoint) sendTCP(r *stack.Route, id stack.TransportEndpointID, data buffer.VectorisedView, ttl uint8, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size, opts []byte, gso *stack.GSO) *tcpip.Error {
-	if err := sendTCP(r, id, data, ttl, flags, seq, ack, rcvWnd, opts, gso); err != nil {
+func (e *endpoint) sendTCP(r *stack.Route, id stack.TransportEndpointID, data buffer.VectorisedView, ttl, tos uint8, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size, opts []byte, gso *stack.GSO) *tcpip.Error {
+	if err := sendTCP(r, id, data, ttl, tos, flags, seq, ack, rcvWnd, opts, gso); err != nil {
 		e.stats.SendErrors.SegmentSendToNetworkFailed.Increment()
 		return err
 	}
@@ -607,7 +609,7 @@ func (e *endpoint) sendTCP(r *stack.Route, id stack.TransportEndpointID, data bu
 
 // sendTCP sends a TCP segment with the provided options via the provided
 // network endpoint and under the provided identity.
-func sendTCP(r *stack.Route, id stack.TransportEndpointID, data buffer.VectorisedView, ttl uint8, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size, opts []byte, gso *stack.GSO) *tcpip.Error {
+func sendTCP(r *stack.Route, id stack.TransportEndpointID, data buffer.VectorisedView, ttl, tos uint8, flags byte, seq, ack seqnum.Value, rcvWnd seqnum.Size, opts []byte, gso *stack.GSO) *tcpip.Error {
 	optLen := len(opts)
 	// Allocate a buffer for the TCP header.
 	hdr := buffer.NewPrependable(header.TCPMinimumSize + int(r.MaxHeaderLength()) + optLen)
@@ -643,7 +645,10 @@ func sendTCP(r *stack.Route, id stack.TransportEndpointID, data buffer.Vectorise
 		tcp.SetChecksum(^tcp.CalculateChecksum(xsum))
 	}
 
-	if err := r.WritePacket(gso, hdr, data, ProtocolNumber, ttl, ttl == 0 /* useDefaultTTL */); err != nil {
+	if ttl == 0 {
+		ttl = r.DefaultTTL()
+	}
+	if err := r.WritePacket(gso, hdr, data, stack.NetworkHeaderParams{Protocol: ProtocolNumber, TTL: ttl, TOS: tos}); err != nil {
 		r.Stats().TCP.SegmentSendErrors.Increment()
 		return err
 	}
@@ -700,7 +705,7 @@ func (e *endpoint) sendRaw(data buffer.VectorisedView, flags byte, seq, ack seqn
 		sackBlocks = e.sack.Blocks[:e.sack.NumBlocks]
 	}
 	options := e.makeOptions(sackBlocks)
-	err := e.sendTCP(&e.route, e.ID, data, e.ttl, flags, seq, ack, rcvWnd, options, e.gso)
+	err := e.sendTCP(&e.route, e.ID, data, e.ttl, e.sendTOS, flags, seq, ack, rcvWnd, options, e.gso)
 	putOptions(options)
 	return err
 }
diff --git a/pkg/tcpip/transport/tcp/dual_stack_test.go b/pkg/tcpip/transport/tcp/dual_stack_test.go
index c54610a87..dfaa4a559 100644
--- a/pkg/tcpip/transport/tcp/dual_stack_test.go
+++ b/pkg/tcpip/transport/tcp/dual_stack_test.go
@@ -42,7 +42,7 @@ func TestV4MappedConnectOnV6Only(t *testing.T) {
 	}
 }
 
-func testV4Connect(t *testing.T, c *context.Context) {
+func testV4Connect(t *testing.T, c *context.Context, checkers ...checker.NetworkChecker) {
 	// Start connection attempt.
 	we, ch := waiter.NewChannelEntry(nil)
 	c.WQ.EventRegister(&we, waiter.EventOut)
@@ -55,12 +55,11 @@ func testV4Connect(t *testing.T, c *context.Context) {
 
 	// Receive SYN packet.
 	b := c.GetPacket()
-	checker.IPv4(t, b,
-		checker.TCP(
-			checker.DstPort(context.TestPort),
-			checker.TCPFlags(header.TCPFlagSyn),
-		),
-	)
+	synCheckers := append(checkers, checker.TCP(
+		checker.DstPort(context.TestPort),
+		checker.TCPFlags(header.TCPFlagSyn),
+	))
+	checker.IPv4(t, b, synCheckers...)
 
 	tcp := header.TCP(header.IPv4(b).Payload())
 	c.IRS = seqnum.Value(tcp.SequenceNumber())
@@ -76,14 +75,13 @@ func testV4Connect(t *testing.T, c *context.Context) {
 	})
 
 	// Receive ACK packet.
-	checker.IPv4(t, c.GetPacket(),
-		checker.TCP(
-			checker.DstPort(context.TestPort),
-			checker.TCPFlags(header.TCPFlagAck),
-			checker.SeqNum(uint32(c.IRS)+1),
-			checker.AckNum(uint32(iss)+1),
-		),
-	)
+	ackCheckers := append(checkers, checker.TCP(
+		checker.DstPort(context.TestPort),
+		checker.TCPFlags(header.TCPFlagAck),
+		checker.SeqNum(uint32(c.IRS)+1),
+		checker.AckNum(uint32(iss)+1),
+	))
+	checker.IPv4(t, c.GetPacket(), ackCheckers...)
 
 	// Wait for connection to be established.
 	select {
@@ -152,7 +150,7 @@ func TestV4ConnectWhenBoundToV4Mapped(t *testing.T) {
 	testV4Connect(t, c)
 }
 
-func testV6Connect(t *testing.T, c *context.Context) {
+func testV6Connect(t *testing.T, c *context.Context, checkers ...checker.NetworkChecker) {
 	// Start connection attempt to IPv6 address.
 	we, ch := waiter.NewChannelEntry(nil)
 	c.WQ.EventRegister(&we, waiter.EventOut)
@@ -165,12 +163,11 @@ func testV6Connect(t *testing.T, c *context.Context) {
 
 	// Receive SYN packet.
 	b := c.GetV6Packet()
-	checker.IPv6(t, b,
-		checker.TCP(
-			checker.DstPort(context.TestPort),
-			checker.TCPFlags(header.TCPFlagSyn),
-		),
-	)
+	synCheckers := append(checkers, checker.TCP(
+		checker.DstPort(context.TestPort),
+		checker.TCPFlags(header.TCPFlagSyn),
+	))
+	checker.IPv6(t, b, synCheckers...)
 
 	tcp := header.TCP(header.IPv6(b).Payload())
 	c.IRS = seqnum.Value(tcp.SequenceNumber())
@@ -186,14 +183,13 @@ func testV6Connect(t *testing.T, c *context.Context) {
 	})
 
 	// Receive ACK packet.
-	checker.IPv6(t, c.GetV6Packet(),
-		checker.TCP(
-			checker.DstPort(context.TestPort),
-			checker.TCPFlags(header.TCPFlagAck),
-			checker.SeqNum(uint32(c.IRS)+1),
-			checker.AckNum(uint32(iss)+1),
-		),
-	)
+	ackCheckers := append(checkers, checker.TCP(
+		checker.DstPort(context.TestPort),
+		checker.TCPFlags(header.TCPFlagAck),
+		checker.SeqNum(uint32(c.IRS)+1),
+		checker.AckNum(uint32(iss)+1),
+	))
+	checker.IPv6(t, c.GetV6Packet(), ackCheckers...)
 
 	// Wait for connection to be established.
 	select {
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 090a8eb24..a1b784b49 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -494,6 +494,10 @@ type endpoint struct {
 	// amss is the advertised MSS to the peer by this endpoint.
 	amss uint16
 
+	// sendTOS represents IPv4 TOS or IPv6 TrafficClass,
+	// applied while sending packets. Defaults to 0 as on Linux.
+	sendTOS uint8
+
 	gso *stack.GSO
 
 	// TODO(b/142022063): Add ability to save and restore per endpoint stats.
@@ -1136,6 +1140,8 @@ func (e *endpoint) SetSockOptInt(opt tcpip.SockOpt, v int) *tcpip.Error {
 
 // SetSockOpt sets a socket option.
 func (e *endpoint) SetSockOpt(opt interface{}) *tcpip.Error {
+	// Lower 2 bits represents ECN bits. RFC 3168, section 23.1
+	const inetECNMask = 3
 	switch v := opt.(type) {
 	case tcpip.DelayOption:
 		if v == 0 {
@@ -1296,6 +1302,23 @@ func (e *endpoint) SetSockOpt(opt interface{}) *tcpip.Error {
 		// Linux returns ENOENT when an invalid congestion
 		// control algorithm is specified.
 		return tcpip.ErrNoSuchFile
+
+	case tcpip.IPv4TOSOption:
+		e.mu.Lock()
+		// TODO(gvisor.dev/issue/995): ECN is not currently supported,
+		// ignore the bits for now.
+		e.sendTOS = uint8(v) & ^uint8(inetECNMask)
+		e.mu.Unlock()
+		return nil
+
+	case tcpip.IPv6TrafficClassOption:
+		e.mu.Lock()
+		// TODO(gvisor.dev/issue/995): ECN is not currently supported,
+		// ignore the bits for now.
+		e.sendTOS = uint8(v) & ^uint8(inetECNMask)
+		e.mu.Unlock()
+		return nil
+
 	default:
 		return nil
 	}
@@ -1495,6 +1518,18 @@ func (e *endpoint) GetSockOpt(opt interface{}) *tcpip.Error {
 		e.mu.Unlock()
 		return nil
 
+	case *tcpip.IPv4TOSOption:
+		e.mu.RLock()
+		*o = tcpip.IPv4TOSOption(e.sendTOS)
+		e.mu.RUnlock()
+		return nil
+
+	case *tcpip.IPv6TrafficClassOption:
+		e.mu.RLock()
+		*o = tcpip.IPv6TrafficClassOption(e.sendTOS)
+		e.mu.RUnlock()
+		return nil
+
 	default:
 		return tcpip.ErrUnknownProtocolOption
 	}
diff --git a/pkg/tcpip/transport/tcp/protocol.go b/pkg/tcpip/transport/tcp/protocol.go
index d5d8ab96a..db40785d3 100644
--- a/pkg/tcpip/transport/tcp/protocol.go
+++ b/pkg/tcpip/transport/tcp/protocol.go
@@ -153,7 +153,7 @@ func replyWithReset(s *segment) {
 
 	ack := s.sequenceNumber.Add(s.logicalLen())
 
-	sendTCP(&s.route, s.id, buffer.VectorisedView{}, s.route.DefaultTTL(), header.TCPFlagRst|header.TCPFlagAck, seq, ack, 0, nil /* options */, nil /* gso */)
+	sendTCP(&s.route, s.id, buffer.VectorisedView{}, s.route.DefaultTTL(), stack.DefaultTOS, header.TCPFlagRst|header.TCPFlagAck, seq, ack, 0 /* rcvWnd */, nil /* options */, nil /* gso */)
 }
 
 // SetOption implements TransportProtocol.SetOption.
diff --git a/pkg/tcpip/transport/tcp/tcp_test.go b/pkg/tcpip/transport/tcp/tcp_test.go
index 8eaf9786d..6d022a266 100644
--- a/pkg/tcpip/transport/tcp/tcp_test.go
+++ b/pkg/tcpip/transport/tcp/tcp_test.go
@@ -474,6 +474,107 @@ func TestSimpleReceive(t *testing.T) {
 	)
 }
 
+func TestTOSV4(t *testing.T) {
+	c := context.New(t, defaultMTU)
+	defer c.Cleanup()
+
+	ep, err := c.Stack().NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &c.WQ)
+	if err != nil {
+		t.Fatalf("NewEndpoint failed: %s", err)
+	}
+	c.EP = ep
+
+	const tos = 0xC0
+	if err := c.EP.SetSockOpt(tcpip.IPv4TOSOption(tos)); err != nil {
+		t.Errorf("SetSockOpt(%#v) failed: %s", tcpip.IPv4TOSOption(tos), err)
+	}
+
+	var v tcpip.IPv4TOSOption
+	if err := c.EP.GetSockOpt(&v); err != nil {
+		t.Errorf("GetSockopt failed: %s", err)
+	}
+
+	if want := tcpip.IPv4TOSOption(tos); v != want {
+		t.Errorf("got GetSockOpt(...) = %#v, want = %#v", v, want)
+	}
+
+	testV4Connect(t, c, checker.TOS(tos, 0))
+
+	data := []byte{1, 2, 3}
+	view := buffer.NewView(len(data))
+	copy(view, data)
+
+	if _, _, err := c.EP.Write(tcpip.SlicePayload(view), tcpip.WriteOptions{}); err != nil {
+		t.Fatalf("Write failed: %s", err)
+	}
+
+	// Check that data is received.
+	b := c.GetPacket()
+	checker.IPv4(t, b,
+		checker.PayloadLen(len(data)+header.TCPMinimumSize),
+		checker.TCP(
+			checker.DstPort(context.TestPort),
+			checker.SeqNum(uint32(c.IRS)+1),
+			checker.AckNum(790), // Acknum is initial sequence number + 1
+			checker.TCPFlagsMatch(header.TCPFlagAck, ^uint8(header.TCPFlagPsh)),
+		),
+		checker.TOS(tos, 0),
+	)
+
+	if p := b[header.IPv4MinimumSize+header.TCPMinimumSize:]; !bytes.Equal(data, p) {
+		t.Errorf("got data = %x, want = %x", p, data)
+	}
+}
+
+func TestTrafficClassV6(t *testing.T) {
+	c := context.New(t, defaultMTU)
+	defer c.Cleanup()
+
+	c.CreateV6Endpoint(false)
+
+	const tos = 0xC0
+	if err := c.EP.SetSockOpt(tcpip.IPv6TrafficClassOption(tos)); err != nil {
+		t.Errorf("SetSockOpt(%#v) failed: %s", tcpip.IPv6TrafficClassOption(tos), err)
+	}
+
+	var v tcpip.IPv6TrafficClassOption
+	if err := c.EP.GetSockOpt(&v); err != nil {
+		t.Fatalf("GetSockopt failed: %s", err)
+	}
+
+	if want := tcpip.IPv6TrafficClassOption(tos); v != want {
+		t.Errorf("got GetSockOpt(...) = %#v, want = %#v", v, want)
+	}
+
+	// Test the connection request.
+	testV6Connect(t, c, checker.TOS(tos, 0))
+
+	data := []byte{1, 2, 3}
+	view := buffer.NewView(len(data))
+	copy(view, data)
+
+	if _, _, err := c.EP.Write(tcpip.SlicePayload(view), tcpip.WriteOptions{}); err != nil {
+		t.Fatalf("Write failed: %s", err)
+	}
+
+	// Check that data is received.
+	b := c.GetV6Packet()
+	checker.IPv6(t, b,
+		checker.PayloadLen(len(data)+header.TCPMinimumSize),
+		checker.TCP(
+			checker.DstPort(context.TestPort),
+			checker.SeqNum(uint32(c.IRS)+1),
+			checker.AckNum(790),
+			checker.TCPFlagsMatch(header.TCPFlagAck, ^uint8(header.TCPFlagPsh)),
+		),
+		checker.TOS(tos, 0),
+	)
+
+	if p := b[header.IPv6MinimumSize+header.TCPMinimumSize:]; !bytes.Equal(data, p) {
+		t.Errorf("got data = %x, want = %x", p, data)
+	}
+}
+
 func TestConnectBindToDevice(t *testing.T) {
 	for _, test := range []struct {
 		name   string
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 2ad7978c2..6e87245b7 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -106,6 +106,10 @@ type endpoint struct {
 	bindToDevice   tcpip.NICID
 	broadcast      bool
 
+	// sendTOS represents IPv4 TOS or IPv6 TrafficClass,
+	// applied while sending packets. Defaults to 0 as on Linux.
+	sendTOS uint8
+
 	// shutdownFlags represent the current shutdown state of the endpoint.
 	shutdownFlags tcpip.ShutdownFlags
 
@@ -429,7 +433,7 @@ func (e *endpoint) write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-c
 		useDefaultTTL = false
 	}
 
-	if err := sendUDP(route, buffer.View(v).ToVectorisedView(), e.ID.LocalPort, dstPort, ttl, useDefaultTTL); err != nil {
+	if err := sendUDP(route, buffer.View(v).ToVectorisedView(), e.ID.LocalPort, dstPort, ttl, useDefaultTTL, e.sendTOS); err != nil {
 		return 0, nil, err
 	}
 	return int64(len(v)), nil, nil
@@ -628,6 +632,18 @@ func (e *endpoint) SetSockOpt(opt interface{}) *tcpip.Error {
 		e.mu.Unlock()
 
 		return nil
+
+	case tcpip.IPv4TOSOption:
+		e.mu.Lock()
+		e.sendTOS = uint8(v)
+		e.mu.Unlock()
+		return nil
+
+	case tcpip.IPv6TrafficClassOption:
+		e.mu.Lock()
+		e.sendTOS = uint8(v)
+		e.mu.Unlock()
+		return nil
 	}
 	return nil
 }
@@ -748,6 +764,18 @@ func (e *endpoint) GetSockOpt(opt interface{}) *tcpip.Error {
 		}
 		return nil
 
+	case *tcpip.IPv4TOSOption:
+		e.mu.RLock()
+		*o = tcpip.IPv4TOSOption(e.sendTOS)
+		e.mu.RUnlock()
+		return nil
+
+	case *tcpip.IPv6TrafficClassOption:
+		e.mu.RLock()
+		*o = tcpip.IPv6TrafficClassOption(e.sendTOS)
+		e.mu.RUnlock()
+		return nil
+
 	default:
 		return tcpip.ErrUnknownProtocolOption
 	}
@@ -755,7 +783,7 @@ func (e *endpoint) GetSockOpt(opt interface{}) *tcpip.Error {
 
 // sendUDP sends a UDP segment via the provided network endpoint and under the
 // provided identity.
-func sendUDP(r *stack.Route, data buffer.VectorisedView, localPort, remotePort uint16, ttl uint8, useDefaultTTL bool) *tcpip.Error {
+func sendUDP(r *stack.Route, data buffer.VectorisedView, localPort, remotePort uint16, ttl uint8, useDefaultTTL bool, tos uint8) *tcpip.Error {
 	// Allocate a buffer for the UDP header.
 	hdr := buffer.NewPrependable(header.UDPMinimumSize + int(r.MaxHeaderLength()))
 
@@ -778,7 +806,10 @@ func sendUDP(r *stack.Route, data buffer.VectorisedView, localPort, remotePort u
 		udp.SetChecksum(^udp.CalculateChecksum(xsum))
 	}
 
-	if err := r.WritePacket(nil /* gso */, hdr, data, ProtocolNumber, ttl, useDefaultTTL); err != nil {
+	if useDefaultTTL {
+		ttl = r.DefaultTTL()
+	}
+	if err := r.WritePacket(nil /* gso */, hdr, data, stack.NetworkHeaderParams{Protocol: ProtocolNumber, TTL: ttl, TOS: tos}); err != nil {
 		r.Stats().UDP.PacketSendErrors.Increment()
 		return err
 	}
diff --git a/pkg/tcpip/transport/udp/protocol.go b/pkg/tcpip/transport/udp/protocol.go
index 0b24bbc85..de026880f 100644
--- a/pkg/tcpip/transport/udp/protocol.go
+++ b/pkg/tcpip/transport/udp/protocol.go
@@ -130,7 +130,7 @@ func (p *protocol) HandleUnknownDestinationPacket(r *stack.Route, id stack.Trans
 		pkt.SetType(header.ICMPv4DstUnreachable)
 		pkt.SetCode(header.ICMPv4PortUnreachable)
 		pkt.SetChecksum(header.ICMPv4Checksum(pkt, payload))
-		r.WritePacket(nil /* gso */, hdr, payload, header.ICMPv4ProtocolNumber, 0, true /* useDefaultTTL */)
+		r.WritePacket(nil /* gso */, hdr, payload, stack.NetworkHeaderParams{Protocol: header.ICMPv4ProtocolNumber, TTL: r.DefaultTTL(), TOS: stack.DefaultTOS})
 
 	case header.IPv6AddressSize:
 		if !r.Stack().AllowICMPMessage() {
@@ -164,7 +164,7 @@ func (p *protocol) HandleUnknownDestinationPacket(r *stack.Route, id stack.Trans
 		pkt.SetType(header.ICMPv6DstUnreachable)
 		pkt.SetCode(header.ICMPv6PortUnreachable)
 		pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, payload))
-		r.WritePacket(nil /* gso */, hdr, payload, header.ICMPv6ProtocolNumber, 0, true /* useDefaultTTL */)
+		r.WritePacket(nil /* gso */, hdr, payload, stack.NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: r.DefaultTTL(), TOS: stack.DefaultTOS})
 	}
 	return true
 }
diff --git a/pkg/tcpip/transport/udp/udp_test.go b/pkg/tcpip/transport/udp/udp_test.go
index 4ada73475..b724d788c 100644
--- a/pkg/tcpip/transport/udp/udp_test.go
+++ b/pkg/tcpip/transport/udp/udp_test.go
@@ -1267,6 +1267,76 @@ func TestSetTTL(t *testing.T) {
 	}
 }
 
+func TestTOSV4(t *testing.T) {
+	for _, flow := range []testFlow{unicastV4, multicastV4, broadcast} {
+		t.Run(fmt.Sprintf("flow:%s", flow), func(t *testing.T) {
+			c := newDualTestContext(t, defaultMTU)
+			defer c.cleanup()
+
+			c.createEndpointForFlow(flow)
+
+			const tos = 0xC0
+			var v tcpip.IPv4TOSOption
+			if err := c.ep.GetSockOpt(&v); err != nil {
+				c.t.Errorf("GetSockopt failed: %s", err)
+			}
+			// Test for expected default value.
+			if v != 0 {
+				c.t.Errorf("got GetSockOpt(...) = %#v, want = %#v", v, 0)
+			}
+
+			if err := c.ep.SetSockOpt(tcpip.IPv4TOSOption(tos)); err != nil {
+				c.t.Errorf("SetSockOpt(%#v) failed: %s", tcpip.IPv4TOSOption(tos), err)
+			}
+
+			if err := c.ep.GetSockOpt(&v); err != nil {
+				c.t.Errorf("GetSockopt failed: %s", err)
+			}
+
+			if want := tcpip.IPv4TOSOption(tos); v != want {
+				c.t.Errorf("got GetSockOpt(...) = %#v, want = %#v", v, want)
+			}
+
+			testWrite(c, flow, checker.TOS(tos, 0))
+		})
+	}
+}
+
+func TestTOSV6(t *testing.T) {
+	for _, flow := range []testFlow{unicastV4in6, unicastV6, unicastV6Only, multicastV4in6, multicastV6, broadcastIn6} {
+		t.Run(fmt.Sprintf("flow:%s", flow), func(t *testing.T) {
+			c := newDualTestContext(t, defaultMTU)
+			defer c.cleanup()
+
+			c.createEndpointForFlow(flow)
+
+			const tos = 0xC0
+			var v tcpip.IPv6TrafficClassOption
+			if err := c.ep.GetSockOpt(&v); err != nil {
+				c.t.Errorf("GetSockopt failed: %s", err)
+			}
+			// Test for expected default value.
+			if v != 0 {
+				c.t.Errorf("got GetSockOpt(...) = %#v, want = %#v", v, 0)
+			}
+
+			if err := c.ep.SetSockOpt(tcpip.IPv6TrafficClassOption(tos)); err != nil {
+				c.t.Errorf("SetSockOpt failed: %s", err)
+			}
+
+			if err := c.ep.GetSockOpt(&v); err != nil {
+				c.t.Errorf("GetSockopt failed: %s", err)
+			}
+
+			if want := tcpip.IPv6TrafficClassOption(tos); v != want {
+				c.t.Errorf("got GetSockOpt(...) = %#v, want = %#v", v, want)
+			}
+
+			testWrite(c, flow, checker.TOS(tos, 0))
+		})
+	}
+}
+
 func TestMulticastInterfaceOption(t *testing.T) {
 	for _, flow := range []testFlow{multicastV4, multicastV4in6, multicastV6, multicastV6Only} {
 		t.Run(fmt.Sprintf("flow:%s", flow), func(t *testing.T) {