Automated rollback of changelist 300217972

PiperOrigin-RevId: 300308974

5 files changed, 53 insertions, 85 deletions

diff --git a/pkg/tcpip/packet_buffer.go b/pkg/tcpip/packet_buffer.go
index 04852132c..ab24372e7 100644
--- a/pkg/tcpip/packet_buffer.go
+++ b/pkg/tcpip/packet_buffer.go
@@ -39,12 +39,8 @@ type PacketBuffer struct {
 	// payload.
 	DataSize int
 
-	// Header holds the headers of outbound packets generated by the netstack. As
-	// a packet is passed down the stack, each layer adds to Header.
-	//
-	// Note, if a packet is being forwarded at the IP layer, the headers for the
-	// IP layer and above (transport) will be held in Data as the packet was not
-	// passed down the stack it arrived at before being forwarded.
+	// Header holds the headers of outbound packets. As a packet is passed
+	// down the stack, each layer adds to Header.
 	Header buffer.Prependable
 
 	// These fields are used by both inbound and outbound packets. They
diff --git a/pkg/tcpip/stack/forwarder_test.go b/pkg/tcpip/stack/forwarder_test.go
index 5a04590d5..321b7524d 100644
--- a/pkg/tcpip/stack/forwarder_test.go
+++ b/pkg/tcpip/stack/forwarder_test.go
@@ -473,7 +473,7 @@ func TestForwardingWithFakeResolverPartialTimeout(t *testing.T) {
 		t.Fatal("packet not forwarded")
 	}
 
-	b := p.Pkt.Data.First()
+	b := p.Pkt.Header.View()
 	if b[0] != 3 {
 		t.Fatalf("got b[0] = %d, want = 3", b[0])
 	}
@@ -517,7 +517,7 @@ func TestForwardingWithFakeResolverTwoPackets(t *testing.T) {
 			t.Fatal("packet not forwarded")
 		}
 
-		b := p.Pkt.Data.First()
+		b := p.Pkt.Header.View()
 		if b[0] != 3 {
 			t.Fatalf("got b[0] = %d, want = 3", b[0])
 		}
@@ -564,7 +564,7 @@ func TestForwardingWithFakeResolverManyPackets(t *testing.T) {
 			t.Fatal("packet not forwarded")
 		}
 
-		b := p.Pkt.Data.First()
+		b := p.Pkt.Header.View()
 		if b[0] != 3 {
 			t.Fatalf("got b[0] = %d, want = 3", b[0])
 		}
@@ -619,7 +619,7 @@ func TestForwardingWithFakeResolverManyResolutions(t *testing.T) {
 
 		// The first 5 packets (address 3 to 7) should not be forwarded
 		// because their address resolutions are interrupted.
-		b := p.Pkt.Data.First()
+		b := p.Pkt.Header.View()
 		if b[0] < 8 {
 			t.Fatalf("got b[0] = %d, want b[0] >= 8", b[0])
 		}
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index e46bd86c6..cd9202aed 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -1246,10 +1246,10 @@ func (n *NIC) DeliverNetworkPacket(linkEP LinkEndpoint, remote, local tcpip.Link
 }
 
 func (n *NIC) forwardPacket(r *Route, protocol tcpip.NetworkProtocolNumber, pkt tcpip.PacketBuffer) {
-	// TODO(b/143425874): Decrease the TTL field in forwarded packets.
+	// TODO(b/143425874) Decrease the TTL field in forwarded packets.
+	pkt.Header = buffer.NewPrependableFromView(pkt.Data.First())
+	pkt.Data.RemoveFirst()
 
-	// pkt.Header should have enough capacity to hold the link's headers.
-	pkt.Header = buffer.NewPrependable(int(n.linkEP.MaxHeaderLength()))
 	if err := n.linkEP.WritePacket(r, nil /* gso */, protocol, pkt); err != nil {
 		r.Stats().IP.OutgoingPacketErrors.Increment()
 		return
diff --git a/pkg/tcpip/stack/stack_test.go b/pkg/tcpip/stack/stack_test.go
index 9515426d6..e15db40fb 100644
--- a/pkg/tcpip/stack/stack_test.go
+++ b/pkg/tcpip/stack/stack_test.go
@@ -2240,84 +2240,56 @@ func TestNICStats(t *testing.T) {
 }
 
 func TestNICForwarding(t *testing.T) {
-	const nicID1 = 1
-	const nicID2 = 2
-	const dstAddr = tcpip.Address("\x03")
+	// Create a stack with the fake network protocol, two NICs, each with
+	// an address.
+	s := stack.New(stack.Options{
+		NetworkProtocols: []stack.NetworkProtocol{fakeNetFactory()},
+	})
+	s.SetForwarding(true)
 
-	tests := []struct {
-		name      string
-		headerLen uint16
-	}{
-		{
-			name: "Zero header length",
-		},
-		{
-			name:      "Non-zero header length",
-			headerLen: 16,
-		},
+	ep1 := channel.New(10, defaultMTU, "")
+	if err := s.CreateNIC(1, ep1); err != nil {
+		t.Fatal("CreateNIC #1 failed:", err)
+	}
+	if err := s.AddAddress(1, fakeNetNumber, "\x01"); err != nil {
+		t.Fatal("AddAddress #1 failed:", err)
 	}
 
-	for _, test := range tests {
-		t.Run(test.name, func(t *testing.T) {
-			s := stack.New(stack.Options{
-				NetworkProtocols: []stack.NetworkProtocol{fakeNetFactory()},
-			})
-			s.SetForwarding(true)
-
-			ep1 := channel.New(10, defaultMTU, "")
-			if err := s.CreateNIC(nicID1, ep1); err != nil {
-				t.Fatalf("CreateNIC(%d, _): %s", nicID1, err)
-			}
-			if err := s.AddAddress(nicID1, fakeNetNumber, "\x01"); err != nil {
-				t.Fatalf("AddAddress(%d, %d, 0x01): %s", nicID1, fakeNetNumber, err)
-			}
-
-			ep2 := channelLinkWithHeaderLength{
-				Endpoint:     channel.New(10, defaultMTU, ""),
-				headerLength: test.headerLen,
-			}
-			if err := s.CreateNIC(nicID2, &ep2); err != nil {
-				t.Fatalf("CreateNIC(%d, _): %s", nicID2, err)
-			}
-			if err := s.AddAddress(nicID2, fakeNetNumber, "\x02"); err != nil {
-				t.Fatalf("AddAddress(%d, %d, 0x02): %s", nicID2, fakeNetNumber, err)
-			}
-
-			// Route all packets to dstAddr to NIC 2.
-			{
-				subnet, err := tcpip.NewSubnet(dstAddr, "\xff")
-				if err != nil {
-					t.Fatal(err)
-				}
-				s.SetRouteTable([]tcpip.Route{{Destination: subnet, Gateway: "\x00", NIC: nicID2}})
-			}
+	ep2 := channel.New(10, defaultMTU, "")
+	if err := s.CreateNIC(2, ep2); err != nil {
+		t.Fatal("CreateNIC #2 failed:", err)
+	}
+	if err := s.AddAddress(2, fakeNetNumber, "\x02"); err != nil {
+		t.Fatal("AddAddress #2 failed:", err)
+	}
 
-			// Send a packet to dstAddr.
-			buf := buffer.NewView(30)
-			buf[0] = dstAddr[0]
-			ep1.InjectInbound(fakeNetNumber, tcpip.PacketBuffer{
-				Data: buf.ToVectorisedView(),
-			})
+	// Route all packets to address 3 to NIC 2.
+	{
+		subnet, err := tcpip.NewSubnet("\x03", "\xff")
+		if err != nil {
+			t.Fatal(err)
+		}
+		s.SetRouteTable([]tcpip.Route{{Destination: subnet, Gateway: "\x00", NIC: 2}})
+	}
 
-			pkt, ok := ep2.Read()
-			if !ok {
-				t.Fatal("packet not forwarded")
-			}
+	// Send a packet to address 3.
+	buf := buffer.NewView(30)
+	buf[0] = 3
+	ep1.InjectInbound(fakeNetNumber, tcpip.PacketBuffer{
+		Data: buf.ToVectorisedView(),
+	})
 
-			// Test that the link's MaxHeaderLength is honoured.
-			if capacity, want := pkt.Pkt.Header.AvailableLength(), int(test.headerLen); capacity != want {
-				t.Errorf("got Header.AvailableLength() = %d, want = %d", capacity, want)
-			}
+	if _, ok := ep2.Read(); !ok {
+		t.Fatal("Packet not forwarded")
+	}
 
-			// Test that forwarding increments Tx stats correctly.
-			if got, want := s.NICInfo()[nicID2].Stats.Tx.Packets.Value(), uint64(1); got != want {
-				t.Errorf("got Tx.Packets.Value() = %d, want = %d", got, want)
-			}
+	// Test that forwarding increments Tx stats correctly.
+	if got, want := s.NICInfo()[2].Stats.Tx.Packets.Value(), uint64(1); got != want {
+		t.Errorf("got Tx.Packets.Value() = %d, want = %d", got, want)
+	}
 
-			if got, want := s.NICInfo()[nicID2].Stats.Tx.Bytes.Value(), uint64(len(buf)); got != want {
-				t.Errorf("got Tx.Bytes.Value() = %d, want = %d", got, want)
-			}
-		})
+	if got, want := s.NICInfo()[2].Stats.Tx.Bytes.Value(), uint64(len(buf)); got != want {
+		t.Errorf("got Tx.Bytes.Value() = %d, want = %d", got, want)
 	}
 }
 
diff --git a/pkg/tcpip/stack/transport_test.go b/pkg/tcpip/stack/transport_test.go
index 3609a25b6..5d1da2f8b 100644
--- a/pkg/tcpip/stack/transport_test.go
+++ b/pkg/tcpip/stack/transport_test.go
@@ -641,10 +641,10 @@ func TestTransportForwarding(t *testing.T) {
 		t.Fatal("Response packet not forwarded")
 	}
 
-	if dst := p.Pkt.Data.First()[0]; dst != 3 {
+	if dst := p.Pkt.Header.View()[0]; dst != 3 {
 		t.Errorf("Response packet has incorrect destination addresss: got = %d, want = 3", dst)
 	}
-	if src := p.Pkt.Data.First()[1]; src != 1 {
+	if src := p.Pkt.Header.View()[1]; src != 1 {
 		t.Errorf("Response packet has incorrect source addresss: got = %d, want = 3", src)
 	}
 }