Update {LinkEndpoint,NetworkEndpoint}#WritePacket to take a VectorisedView

Makes it possible to avoid copying or allocating in cases where DeliverNetworkPacket (rx)
needs to turn around and call WritePacket (tx) with its VectorisedView.

Also removes the restriction on having VectorisedViews with multiple views in the write path.

PiperOrigin-RevId: 211728717
Change-Id: Ie03a65ecb4e28bd15ebdb9c69f05eced18fdfcff

4 files changed, 7 insertions, 7 deletions

diff --git a/pkg/tcpip/stack/registration.go b/pkg/tcpip/stack/registration.go
index bbe887144..b9e2cc045 100644
--- a/pkg/tcpip/stack/registration.go
+++ b/pkg/tcpip/stack/registration.go
@@ -141,7 +141,7 @@ type NetworkEndpoint interface {
 
 	// WritePacket writes a packet to the given destination address and
 	// protocol.
-	WritePacket(r *Route, hdr *buffer.Prependable, payload buffer.View, protocol tcpip.TransportProtocolNumber) *tcpip.Error
+	WritePacket(r *Route, hdr *buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.TransportProtocolNumber) *tcpip.Error
 
 	// ID returns the network protocol endpoint ID.
 	ID() *NetworkEndpointID
@@ -234,7 +234,7 @@ type LinkEndpoint interface {
 
 	// WritePacket writes a packet with the given protocol through the given
 	// route.
-	WritePacket(r *Route, hdr *buffer.Prependable, payload buffer.View, protocol tcpip.NetworkProtocolNumber) *tcpip.Error
+	WritePacket(r *Route, hdr *buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.NetworkProtocolNumber) *tcpip.Error
 
 	// Attach attaches the data link layer endpoint to the network-layer
 	// dispatcher of the stack.
diff --git a/pkg/tcpip/stack/route.go b/pkg/tcpip/stack/route.go
index 63a20e031..533a0b560 100644
--- a/pkg/tcpip/stack/route.go
+++ b/pkg/tcpip/stack/route.go
@@ -129,7 +129,7 @@ func (r *Route) IsResolutionRequired() bool {
 }
 
 // WritePacket writes the packet through the given route.
-func (r *Route) WritePacket(hdr *buffer.Prependable, payload buffer.View, protocol tcpip.TransportProtocolNumber) *tcpip.Error {
+func (r *Route) WritePacket(hdr *buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.TransportProtocolNumber) *tcpip.Error {
 	err := r.ref.ep.WritePacket(r, hdr, payload, protocol)
 	if err == tcpip.ErrNoRoute {
 		r.Stats().IP.OutgoingPacketErrors.Increment()
diff --git a/pkg/tcpip/stack/stack_test.go b/pkg/tcpip/stack/stack_test.go
index c46e91241..02f02dfa2 100644
--- a/pkg/tcpip/stack/stack_test.go
+++ b/pkg/tcpip/stack/stack_test.go
@@ -105,7 +105,7 @@ func (f *fakeNetworkEndpoint) Capabilities() stack.LinkEndpointCapabilities {
 	return f.linkEP.Capabilities()
 }
 
-func (f *fakeNetworkEndpoint) WritePacket(r *stack.Route, hdr *buffer.Prependable, payload buffer.View, protocol tcpip.TransportProtocolNumber) *tcpip.Error {
+func (f *fakeNetworkEndpoint) WritePacket(r *stack.Route, hdr *buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.TransportProtocolNumber) *tcpip.Error {
 	// Increment the sent packet count in the protocol descriptor.
 	f.proto.sendPacketCount[int(r.RemoteAddress[0])%len(f.proto.sendPacketCount)]++
 
@@ -269,8 +269,7 @@ func sendTo(t *testing.T, s *stack.Stack, addr tcpip.Address) {
 	defer r.Release()
 
 	hdr := buffer.NewPrependable(int(r.MaxHeaderLength()))
-	err = r.WritePacket(&hdr, nil, fakeTransNumber)
-	if err != nil {
+	if err := r.WritePacket(&hdr, buffer.VectorisedView{}, fakeTransNumber); err != nil {
 		t.Errorf("WritePacket failed: %v", err)
 		return
 	}
diff --git a/pkg/tcpip/stack/transport_test.go b/pkg/tcpip/stack/transport_test.go
index 98d2f9d99..5ab485c98 100644
--- a/pkg/tcpip/stack/transport_test.go
+++ b/pkg/tcpip/stack/transport_test.go
@@ -70,7 +70,8 @@ func (f *fakeTransportEndpoint) Write(p tcpip.Payload, opts tcpip.WriteOptions)
 	if err != nil {
 		return 0, err
 	}
-	if err := f.route.WritePacket(&hdr, v, fakeTransNumber); err != nil {
+	vv := buffer.NewVectorisedView(len(v), []buffer.View{v})
+	if err := f.route.WritePacket(&hdr, vv, fakeTransNumber); err != nil {
 		return 0, err
 	}