5 files changed, 24 insertions, 12 deletions
diff --git a/pkg/tcpip/stack/registration.go b/pkg/tcpip/stack/registration.go
index 80101d4bb..9d6157f22 100644
--- a/pkg/tcpip/stack/registration.go
+++ b/pkg/tcpip/stack/registration.go
@@ -146,6 +146,19 @@ const (
 	PacketLoop
 )
 
+// NetworkHeaderParams are the header parameters given as input by the
+// transport endpoint to the network.
+type NetworkHeaderParams struct {
+	// Protocol refers to the transport protocol number.
+	Protocol tcpip.TransportProtocolNumber
+
+	// TTL refers to Time To Live field of the IP-header.
+	TTL uint8
+
+	// TOS refers to TypeOfService or TrafficClass field of the IP-header.
+	TOS uint8
+}
+
 // NetworkEndpoint is the interface that needs to be implemented by endpoints
 // of network layer protocols (e.g., ipv4, ipv6).
 type NetworkEndpoint interface {
@@ -170,7 +183,7 @@ type NetworkEndpoint interface {
 
 	// WritePacket writes a packet to the given destination address and
 	// protocol.
-	WritePacket(r *Route, gso *GSO, hdr buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.TransportProtocolNumber, ttl uint8, loop PacketLooping) *tcpip.Error
+	WritePacket(r *Route, gso *GSO, hdr buffer.Prependable, payload buffer.VectorisedView, params NetworkHeaderParams, loop PacketLooping) *tcpip.Error
 
 	// WriteHeaderIncludedPacket writes a packet that includes a network
 	// header to the given destination address.
diff --git a/pkg/tcpip/stack/route.go b/pkg/tcpip/stack/route.go
index 22db619a1..e72373964 100644
--- a/pkg/tcpip/stack/route.go
+++ b/pkg/tcpip/stack/route.go
@@ -154,16 +154,12 @@ func (r *Route) IsResolutionRequired() bool {
 }
 
 // WritePacket writes the packet through the given route.
-func (r *Route) WritePacket(gso *GSO, hdr buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.TransportProtocolNumber, ttl uint8, useDefaultTTL bool) *tcpip.Error {
+func (r *Route) WritePacket(gso *GSO, hdr buffer.Prependable, payload buffer.VectorisedView, params NetworkHeaderParams) *tcpip.Error {
 	if !r.ref.isValidForOutgoing() {
 		return tcpip.ErrInvalidEndpointState
 	}
 
-	if useDefaultTTL {
-		ttl = r.DefaultTTL()
-	}
-
-	err := r.ref.ep.WritePacket(r, gso, hdr, payload, protocol, ttl, r.loop)
+	err := r.ref.ep.WritePacket(r, gso, hdr, payload, params, r.loop)
 	if err != nil {
 		r.Stats().IP.OutgoingPacketErrors.Increment()
 	} else {
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index 7d73389cc..f67975525 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -43,6 +43,9 @@ const (
 	resolutionTimeout = 1 * time.Second
 	// resolutionAttempts is set to the same ARP retries used in Linux.
 	resolutionAttempts = 3
+
+	// DefaultTOS is the default type of service value for network endpoints.
+	DefaultTOS = 0
 )
 
 type transportProtocolState struct {
@@ -394,7 +397,7 @@ type Stack struct {
 	// portSeed is a one-time random value initialized at stack startup
 	// and is used to seed the TCP port picking on active connections
 	//
-	// TODO(gvisor.dev/issues/940): S/R this field.
+	// TODO(gvisor.dev/issue/940): S/R this field.
 	portSeed uint32
 }
 
diff --git a/pkg/tcpip/stack/stack_test.go b/pkg/tcpip/stack/stack_test.go
index 8f063038b..10fd1065f 100644
--- a/pkg/tcpip/stack/stack_test.go
+++ b/pkg/tcpip/stack/stack_test.go
@@ -119,7 +119,7 @@ func (f *fakeNetworkEndpoint) Capabilities() stack.LinkEndpointCapabilities {
 	return f.ep.Capabilities()
 }
 
-func (f *fakeNetworkEndpoint) WritePacket(r *stack.Route, gso *stack.GSO, hdr buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.TransportProtocolNumber, _ uint8, loop stack.PacketLooping) *tcpip.Error {
+func (f *fakeNetworkEndpoint) WritePacket(r *stack.Route, gso *stack.GSO, hdr buffer.Prependable, payload buffer.VectorisedView, params stack.NetworkHeaderParams, loop stack.PacketLooping) *tcpip.Error {
 	// Increment the sent packet count in the protocol descriptor.
 	f.proto.sendPacketCount[int(r.RemoteAddress[0])%len(f.proto.sendPacketCount)]++
 
@@ -128,7 +128,7 @@ func (f *fakeNetworkEndpoint) WritePacket(r *stack.Route, gso *stack.GSO, hdr bu
 	b := hdr.Prepend(fakeNetHeaderLen)
 	b[0] = r.RemoteAddress[0]
 	b[1] = f.id.LocalAddress[0]
-	b[2] = byte(protocol)
+	b[2] = byte(params.Protocol)
 
 	if loop&stack.PacketLoop != 0 {
 		views := make([]buffer.View, 1, 1+len(payload.Views()))
@@ -310,7 +310,7 @@ func sendTo(s *stack.Stack, addr tcpip.Address, payload buffer.View) *tcpip.Erro
 
 func send(r stack.Route, payload buffer.View) *tcpip.Error {
 	hdr := buffer.NewPrependable(int(r.MaxHeaderLength()))
-	return r.WritePacket(nil /* gso */, hdr, payload.ToVectorisedView(), fakeTransNumber, 123 /* ttl */, false /* useDefaultTTL */)
+	return r.WritePacket(nil /* gso */, hdr, payload.ToVectorisedView(), stack.NetworkHeaderParams{Protocol: fakeTransNumber, TTL: 123, TOS: stack.DefaultTOS})
 }
 
 func testSendTo(t *testing.T, s *stack.Stack, addr tcpip.Address, ep *channel.Endpoint, payload buffer.View) {
diff --git a/pkg/tcpip/stack/transport_test.go b/pkg/tcpip/stack/transport_test.go
index 63811c684..86c62be25 100644
--- a/pkg/tcpip/stack/transport_test.go
+++ b/pkg/tcpip/stack/transport_test.go
@@ -82,7 +82,7 @@ func (f *fakeTransportEndpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions
 	if err != nil {
 		return 0, nil, err
 	}
-	if err := f.route.WritePacket(nil /* gso */, hdr, buffer.View(v).ToVectorisedView(), fakeTransNumber, 123 /* ttl */, false /* useDefaultTTL */); err != nil {
+	if err := f.route.WritePacket(nil /* gso */, hdr, buffer.View(v).ToVectorisedView(), stack.NetworkHeaderParams{Protocol: fakeTransNumber, TTL: 123, TOS: stack.DefaultTOS}); err != nil {
 		return 0, nil, err
 	}