Make dedicated methods for data operations in PacketBuffer

One of the preparation to decouple underlying buffer implementation.
There are still some methods that tie to VectorisedView, and they will be
changed gradually in later CLs.

This CL also introduce a new ICMPv6ChecksumParams to replace long list of
parameters when calling ICMPv6Checksum, aiming to be more descriptive.

PiperOrigin-RevId: 360778149

4 files changed, 13 insertions, 15 deletions

diff --git a/pkg/tcpip/network/internal/fragmentation/fragmentation.go b/pkg/tcpip/network/internal/fragmentation/fragmentation.go
index 243738951..5168f5361 100644
--- a/pkg/tcpip/network/internal/fragmentation/fragmentation.go
+++ b/pkg/tcpip/network/internal/fragmentation/fragmentation.go
@@ -170,7 +170,7 @@ func (f *Fragmentation) Process(
 		return nil, 0, false, fmt.Errorf("fragment size=%d bytes is not a multiple of block size=%d on non-final fragment: %w", fragmentSize, f.blockSize, ErrInvalidArgs)
 	}
 
-	if l := pkt.Data.Size(); l != int(fragmentSize) {
+	if l := pkt.Data().Size(); l != int(fragmentSize) {
 		return nil, 0, false, fmt.Errorf("got fragment size=%d bytes not equal to the expected fragment size=%d bytes (first=%d last=%d): %w", l, fragmentSize, first, last, ErrInvalidArgs)
 	}
 
@@ -293,7 +293,7 @@ func MakePacketFragmenter(pkt *stack.PacketBuffer, fragmentPayloadLen uint32, re
 	// these headers.
 	var fragmentableData buffer.VectorisedView
 	fragmentableData.AppendView(pkt.TransportHeader().View())
-	fragmentableData.Append(pkt.Data)
+	fragmentableData.Append(pkt.Data().ExtractVV())
 	fragmentCount := (uint32(fragmentableData.Size()) + fragmentPayloadLen - 1) / fragmentPayloadLen
 
 	return PacketFragmenter{
@@ -323,7 +323,7 @@ func (pf *PacketFragmenter) BuildNextFragment() (*stack.PacketBuffer, int, int,
 	})
 
 	// Copy data for the fragment.
-	copied := pf.data.ReadToVV(&fragPkt.Data, pf.fragmentPayloadLen)
+	copied := fragPkt.Data().ReadFromVV(&pf.data, pf.fragmentPayloadLen)
 
 	offset := pf.fragmentOffset
 	pf.fragmentOffset += copied
diff --git a/pkg/tcpip/network/internal/fragmentation/fragmentation_test.go b/pkg/tcpip/network/internal/fragmentation/fragmentation_test.go
index 47ea3173e..7daf64b4a 100644
--- a/pkg/tcpip/network/internal/fragmentation/fragmentation_test.go
+++ b/pkg/tcpip/network/internal/fragmentation/fragmentation_test.go
@@ -121,7 +121,7 @@ func TestFragmentationProcess(t *testing.T) {
 						in.id, in.first, in.last, in.more, in.proto, done, c.out[i].done)
 				}
 				if c.out[i].done {
-					if diff := cmp.Diff(c.out[i].vv.ToOwnedView(), resPkt.Data.ToOwnedView()); diff != "" {
+					if diff := cmp.Diff(c.out[i].vv.ToOwnedView(), resPkt.Data().AsRange().ToOwnedView()); diff != "" {
 						t.Errorf("got Process(%+v, %d, %d, %t, %d, %#v) result mismatch (-want, +got):\n%s",
 							in.id, in.first, in.last, in.more, in.proto, in.pkt, diff)
 					}
@@ -470,9 +470,7 @@ func TestPacketFragmenter(t *testing.T) {
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 			pkt := testutil.MakeRandPkt(test.transportHeaderLen, reserve, []int{test.payloadSize}, proto)
-			var originalPayload buffer.VectorisedView
-			originalPayload.AppendView(pkt.TransportHeader().View())
-			originalPayload.Append(pkt.Data)
+			originalPayload := stack.PayloadSince(pkt.TransportHeader())
 			var reassembledPayload buffer.VectorisedView
 			pf := MakePacketFragmenter(pkt, test.fragmentPayloadLen, reserve)
 			for i := 0; ; i++ {
@@ -499,7 +497,7 @@ func TestPacketFragmenter(t *testing.T) {
 				if got := fragPkt.TransportHeader().View().Size(); got != 0 {
 					t.Errorf("(fragment #%d) got fragPkt.TransportHeader().View().Size() = %d, want = 0", i, got)
 				}
-				reassembledPayload.Append(fragPkt.Data)
+				reassembledPayload.AppendViews(fragPkt.Data().Views())
 				if !more {
 					if i != len(test.wantFragments)-1 {
 						t.Errorf("got fragment count = %d, want = %d", i, len(test.wantFragments)-1)
@@ -507,7 +505,7 @@ func TestPacketFragmenter(t *testing.T) {
 					break
 				}
 			}
-			if diff := cmp.Diff(reassembledPayload.ToView(), originalPayload.ToView()); diff != "" {
+			if diff := cmp.Diff(reassembledPayload.ToView(), originalPayload); diff != "" {
 				t.Errorf("reassembledPayload mismatch (-want +got):\n%s", diff)
 			}
 		})
@@ -625,11 +623,11 @@ func TestTimeoutHandler(t *testing.T) {
 			}
 			switch {
 			case handler.pkt != nil && test.wantPkt == nil:
-				t.Errorf("got handler.pkt = not nil (pkt.Data = %x), want = nil", handler.pkt.Data.ToView())
+				t.Errorf("got handler.pkt = not nil (pkt.Data = %x), want = nil", handler.pkt.Data().AsRange().ToOwnedView())
 			case handler.pkt == nil && test.wantPkt != nil:
-				t.Errorf("got handler.pkt = nil, want = not nil (pkt.Data = %x)", test.wantPkt.Data.ToView())
+				t.Errorf("got handler.pkt = nil, want = not nil (pkt.Data = %x)", test.wantPkt.Data().AsRange().ToOwnedView())
 			case handler.pkt != nil && test.wantPkt != nil:
-				if diff := cmp.Diff(test.wantPkt.Data.ToView(), handler.pkt.Data.ToView()); diff != "" {
+				if diff := cmp.Diff(test.wantPkt.Data().AsRange().ToOwnedView(), handler.pkt.Data().AsRange().ToOwnedView()); diff != "" {
 					t.Errorf("pkt.Data mismatch (-want, +got):\n%s", diff)
 				}
 			}
diff --git a/pkg/tcpip/network/internal/fragmentation/reassembler.go b/pkg/tcpip/network/internal/fragmentation/reassembler.go
index 933d63d32..90075a70c 100644
--- a/pkg/tcpip/network/internal/fragmentation/reassembler.go
+++ b/pkg/tcpip/network/internal/fragmentation/reassembler.go
@@ -167,8 +167,8 @@ func (r *reassembler) process(first, last uint16, more bool, proto uint8, pkt *s
 
 	resPkt := r.holes[0].pkt
 	for i := 1; i < len(r.holes); i++ {
-		fragPkt := r.holes[i].pkt
-		fragPkt.Data.ReadToVV(&resPkt.Data, fragPkt.Data.Size())
+		fragData := r.holes[i].pkt.Data()
+		resPkt.Data().ReadFromData(fragData, fragData.Size())
 	}
 	return resPkt, r.proto, true, memConsumed, nil
 }
diff --git a/pkg/tcpip/network/internal/fragmentation/reassembler_test.go b/pkg/tcpip/network/internal/fragmentation/reassembler_test.go
index 214a93709..cfd9f00ef 100644
--- a/pkg/tcpip/network/internal/fragmentation/reassembler_test.go
+++ b/pkg/tcpip/network/internal/fragmentation/reassembler_test.go
@@ -204,7 +204,7 @@ func TestReassemblerProcess(t *testing.T) {
 				if a == nil || b == nil {
 					return a == b
 				}
-				return bytes.Equal(a.Data.ToOwnedView(), b.Data.ToOwnedView())
+				return bytes.Equal(a.Data().AsRange().ToOwnedView(), b.Data().AsRange().ToOwnedView())
 			}
 
 			if isDone {