Use PacketBuffers, rather than VectorisedViews, in netstack.

PacketBuffers are analogous to Linux's sk_buff. They hold all information about
a packet, headers, and payload. This is important for:

* iptables to access various headers of packets
* Preventing the clutter of passing different net and link headers along with
  VectorisedViews to packet handling functions.

This change only affects the incoming packet path, and a future change will
change the outgoing path.

Benchmark               Regular         PacketBufferPtr  PacketBufferConcrete
--------------------------------------------------------------------------------
BM_Recvmsg             400.715MB/s      373.676MB/s      396.276MB/s
BM_Sendmsg             361.832MB/s      333.003MB/s      335.571MB/s
BM_Recvfrom            453.336MB/s      393.321MB/s      381.650MB/s
BM_Sendto              378.052MB/s      372.134MB/s      341.342MB/s
BM_SendmsgTCP/0/1k     353.711MB/s      316.216MB/s      322.747MB/s
BM_SendmsgTCP/0/2k     600.681MB/s      588.776MB/s      565.050MB/s
BM_SendmsgTCP/0/4k     995.301MB/s      888.808MB/s      941.888MB/s
BM_SendmsgTCP/0/8k     1.517GB/s        1.274GB/s        1.345GB/s
BM_SendmsgTCP/0/16k    1.872GB/s        1.586GB/s        1.698GB/s
BM_SendmsgTCP/0/32k    1.017GB/s        1.020GB/s        1.133GB/s
BM_SendmsgTCP/0/64k    475.626MB/s      584.587MB/s      627.027MB/s
BM_SendmsgTCP/0/128k   416.371MB/s      503.434MB/s      409.850MB/s
BM_SendmsgTCP/0/256k   323.449MB/s      449.599MB/s      388.852MB/s
BM_SendmsgTCP/0/512k   243.992MB/s      267.676MB/s      314.474MB/s
BM_SendmsgTCP/0/1M     95.138MB/s       95.874MB/s       95.417MB/s
BM_SendmsgTCP/0/2M     96.261MB/s       94.977MB/s       96.005MB/s
BM_SendmsgTCP/0/4M     96.512MB/s       95.978MB/s       95.370MB/s
BM_SendmsgTCP/0/8M     95.603MB/s       95.541MB/s       94.935MB/s
BM_SendmsgTCP/0/16M    94.598MB/s       94.696MB/s       94.521MB/s
BM_SendmsgTCP/0/32M    94.006MB/s       94.671MB/s       94.768MB/s
BM_SendmsgTCP/0/64M    94.133MB/s       94.333MB/s       94.746MB/s
BM_SendmsgTCP/0/128M   93.615MB/s       93.497MB/s       93.573MB/s
BM_SendmsgTCP/0/256M   93.241MB/s       95.100MB/s       93.272MB/s
BM_SendmsgTCP/1/1k     303.644MB/s      316.074MB/s      308.430MB/s
BM_SendmsgTCP/1/2k     537.093MB/s      584.962MB/s      529.020MB/s
BM_SendmsgTCP/1/4k     882.362MB/s      939.087MB/s      892.285MB/s
BM_SendmsgTCP/1/8k     1.272GB/s        1.394GB/s        1.296GB/s
BM_SendmsgTCP/1/16k    1.802GB/s        2.019GB/s        1.830GB/s
BM_SendmsgTCP/1/32k    2.084GB/s        2.173GB/s        2.156GB/s
BM_SendmsgTCP/1/64k    2.515GB/s        2.463GB/s        2.473GB/s
BM_SendmsgTCP/1/128k   2.811GB/s        3.004GB/s        2.946GB/s
BM_SendmsgTCP/1/256k   3.008GB/s        3.159GB/s        3.171GB/s
BM_SendmsgTCP/1/512k   2.980GB/s        3.150GB/s        3.126GB/s
BM_SendmsgTCP/1/1M     2.165GB/s        2.233GB/s        2.163GB/s
BM_SendmsgTCP/1/2M     2.370GB/s        2.219GB/s        2.453GB/s
BM_SendmsgTCP/1/4M     2.005GB/s        2.091GB/s        2.214GB/s
BM_SendmsgTCP/1/8M     2.111GB/s        2.013GB/s        2.109GB/s
BM_SendmsgTCP/1/16M    1.902GB/s        1.868GB/s        1.897GB/s
BM_SendmsgTCP/1/32M    1.655GB/s        1.665GB/s        1.635GB/s
BM_SendmsgTCP/1/64M    1.575GB/s        1.547GB/s        1.575GB/s
BM_SendmsgTCP/1/128M   1.524GB/s        1.584GB/s        1.580GB/s
BM_SendmsgTCP/1/256M   1.579GB/s        1.607GB/s        1.593GB/s

PiperOrigin-RevId: 278940079

4 files changed, 32 insertions, 22 deletions

diff --git a/pkg/tcpip/link/fdbased/endpoint.go b/pkg/tcpip/link/fdbased/endpoint.go
index ae4858529..edef7db26 100644
--- a/pkg/tcpip/link/fdbased/endpoint.go
+++ b/pkg/tcpip/link/fdbased/endpoint.go
@@ -598,8 +598,8 @@ func (e *InjectableEndpoint) Attach(dispatcher stack.NetworkDispatcher) {
 }
 
 // InjectInbound injects an inbound packet.
-func (e *InjectableEndpoint) InjectInbound(protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView) {
-	e.dispatcher.DeliverNetworkPacket(e, "" /* remote */, "" /* local */, protocol, vv, nil /* linkHeader */)
+func (e *InjectableEndpoint) InjectInbound(protocol tcpip.NetworkProtocolNumber, pkt tcpip.PacketBuffer) {
+	e.dispatcher.DeliverNetworkPacket(e, "" /* remote */, "" /* local */, protocol, pkt)
 }
 
 // NewInjectable creates a new fd-based InjectableEndpoint.
diff --git a/pkg/tcpip/link/fdbased/endpoint_test.go b/pkg/tcpip/link/fdbased/endpoint_test.go
index e7c05ca4f..7e08e033b 100644
--- a/pkg/tcpip/link/fdbased/endpoint_test.go
+++ b/pkg/tcpip/link/fdbased/endpoint_test.go
@@ -43,10 +43,9 @@ const (
 )
 
 type packetInfo struct {
-	raddr      tcpip.LinkAddress
-	proto      tcpip.NetworkProtocolNumber
-	contents   buffer.VectorisedView
-	linkHeader buffer.View
+	raddr    tcpip.LinkAddress
+	proto    tcpip.NetworkProtocolNumber
+	contents tcpip.PacketBuffer
 }
 
 type context struct {
@@ -93,8 +92,8 @@ func (c *context) cleanup() {
 	syscall.Close(c.fds[1])
 }
 
-func (c *context) DeliverNetworkPacket(linkEP stack.LinkEndpoint, remote tcpip.LinkAddress, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView, linkHeader buffer.View) {
-	c.ch <- packetInfo{remote, protocol, vv, linkHeader}
+func (c *context) DeliverNetworkPacket(linkEP stack.LinkEndpoint, remote tcpip.LinkAddress, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt tcpip.PacketBuffer) {
+	c.ch <- packetInfo{remote, protocol, pkt}
 }
 
 func TestNoEthernetProperties(t *testing.T) {
@@ -317,19 +316,21 @@ func TestDeliverPacket(t *testing.T) {
 				select {
 				case pi := <-c.ch:
 					want := packetInfo{
-						raddr:      raddr,
-						proto:      proto,
-						contents:   buffer.View(b).ToVectorisedView(),
-						linkHeader: buffer.View(hdr),
+						raddr: raddr,
+						proto: proto,
+						contents: tcpip.PacketBuffer{
+							Data:       buffer.View(b).ToVectorisedView(),
+							LinkHeader: buffer.View(hdr),
+						},
 					}
 					if !eth {
 						want.proto = header.IPv4ProtocolNumber
 						want.raddr = ""
 					}
-					// want.contents will be a single view,
-					// so make pi do the same for the
+					// want.contents.Data will be a single
+					// view, so make pi do the same for the
 					// DeepEqual check.
-					pi.contents = pi.contents.ToView().ToVectorisedView()
+					pi.contents.Data = pi.contents.Data.ToView().ToVectorisedView()
 					if !reflect.DeepEqual(want, pi) {
 						t.Fatalf("Unexpected received packet: %+v, want %+v", pi, want)
 					}
diff --git a/pkg/tcpip/link/fdbased/mmap.go b/pkg/tcpip/link/fdbased/mmap.go
index 554d45715..62ed1e569 100644
--- a/pkg/tcpip/link/fdbased/mmap.go
+++ b/pkg/tcpip/link/fdbased/mmap.go
@@ -190,6 +190,9 @@ func (d *packetMMapDispatcher) dispatch() (bool, *tcpip.Error) {
 	}
 
 	pkt = pkt[d.e.hdrSize:]
-	d.e.dispatcher.DeliverNetworkPacket(d.e, remote, local, p, buffer.NewVectorisedView(len(pkt), []buffer.View{buffer.View(pkt)}), buffer.View(eth))
+	d.e.dispatcher.DeliverNetworkPacket(d.e, remote, local, p, tcpip.PacketBuffer{
+		Data:       buffer.View(pkt).ToVectorisedView(),
+		LinkHeader: buffer.View(eth),
+	})
 	return true, nil
 }
diff --git a/pkg/tcpip/link/fdbased/packet_dispatchers.go b/pkg/tcpip/link/fdbased/packet_dispatchers.go
index 3331b6453..c67d684ce 100644
--- a/pkg/tcpip/link/fdbased/packet_dispatchers.go
+++ b/pkg/tcpip/link/fdbased/packet_dispatchers.go
@@ -139,10 +139,13 @@ func (d *readVDispatcher) dispatch() (bool, *tcpip.Error) {
 	}
 
 	used := d.capViews(n, BufConfig)
-	vv := buffer.NewVectorisedView(n, append([]buffer.View(nil), d.views[:used]...))
-	vv.TrimFront(d.e.hdrSize)
+	pkt := tcpip.PacketBuffer{
+		Data:       buffer.NewVectorisedView(n, append([]buffer.View(nil), d.views[:used]...)),
+		LinkHeader: buffer.View(eth),
+	}
+	pkt.Data.TrimFront(d.e.hdrSize)
 
-	d.e.dispatcher.DeliverNetworkPacket(d.e, remote, local, p, vv, buffer.View(eth))
+	d.e.dispatcher.DeliverNetworkPacket(d.e, remote, local, p, pkt)
 
 	// Prepare e.views for another packet: release used views.
 	for i := 0; i < used; i++ {
@@ -293,9 +296,12 @@ func (d *recvMMsgDispatcher) dispatch() (bool, *tcpip.Error) {
 		}
 
 		used := d.capViews(k, int(n), BufConfig)
-		vv := buffer.NewVectorisedView(int(n), append([]buffer.View(nil), d.views[k][:used]...))
-		vv.TrimFront(d.e.hdrSize)
-		d.e.dispatcher.DeliverNetworkPacket(d.e, remote, local, p, vv, buffer.View(eth))
+		pkt := tcpip.PacketBuffer{
+			Data:       buffer.NewVectorisedView(int(n), append([]buffer.View(nil), d.views[k][:used]...)),
+			LinkHeader: buffer.View(eth),
+		}
+		pkt.Data.TrimFront(d.e.hdrSize)
+		d.e.dispatcher.DeliverNetworkPacket(d.e, remote, local, p, pkt)
 
 		// Prepare e.views for another packet: release used views.
 		for i := 0; i < used; i++ {