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

8 files changed, 25 insertions, 19 deletions

diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index f5e1a6e45..09e9d027d 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -417,7 +417,7 @@ func send4(r *stack.Route, ident uint16, data buffer.View, ttl uint8, owner tcpi
 	icmpv4.SetChecksum(0)
 	icmpv4.SetChecksum(^header.Checksum(icmpv4, header.Checksum(data, 0)))
 
-	pkt.Data = data.ToVectorisedView()
+	pkt.Data().AppendView(data)
 
 	if ttl == 0 {
 		ttl = r.DefaultTTL()
@@ -445,9 +445,15 @@ func send6(r *stack.Route, ident uint16, data buffer.View, ttl uint8) tcpip.Erro
 		return &tcpip.ErrInvalidEndpointState{}
 	}
 
-	dataVV := data.ToVectorisedView()
-	icmpv6.SetChecksum(header.ICMPv6Checksum(icmpv6, r.LocalAddress, r.RemoteAddress, dataVV))
-	pkt.Data = dataVV
+	pkt.Data().AppendView(data)
+	dataRange := pkt.Data().AsRange()
+	icmpv6.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+		Header:      icmpv6,
+		Src:         r.LocalAddress,
+		Dst:         r.RemoteAddress,
+		PayloadCsum: dataRange.Checksum(),
+		PayloadLen:  dataRange.Size(),
+	}))
 
 	if ttl == 0 {
 		ttl = r.DefaultTTL()
@@ -763,7 +769,7 @@ func (e *endpoint) HandlePacket(id stack.TransportEndpointID, pkt *stack.PacketB
 
 	// ICMP socket's data includes ICMP header.
 	packet.data = pkt.TransportHeader().View().ToVectorisedView()
-	packet.data.Append(pkt.Data)
+	packet.data.Append(pkt.Data().ExtractVV())
 
 	e.rcvList.PushBack(packet)
 	e.rcvBufSize += packet.data.Size()
diff --git a/pkg/tcpip/transport/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go
index 73bb66830..367757d3b 100644
--- a/pkg/tcpip/transport/packet/endpoint.go
+++ b/pkg/tcpip/transport/packet/endpoint.go
@@ -432,7 +432,7 @@ func (ep *endpoint) HandlePacket(nicID tcpip.NICID, localAddr tcpip.LinkAddress,
 		// Cooked packets can simply be queued.
 		switch pkt.PktType {
 		case tcpip.PacketHost:
-			packet.data = pkt.Data
+			packet.data = pkt.Data().ExtractVV()
 		case tcpip.PacketOutgoing:
 			// Strip Link Header.
 			var combinedVV buffer.VectorisedView
@@ -442,7 +442,7 @@ func (ep *endpoint) HandlePacket(nicID tcpip.NICID, localAddr tcpip.LinkAddress,
 			if v := pkt.TransportHeader().View(); !v.IsEmpty() {
 				combinedVV.AppendView(v)
 			}
-			combinedVV.Append(pkt.Data)
+			combinedVV.Append(pkt.Data().ExtractVV())
 			packet.data = combinedVV
 		default:
 			panic(fmt.Sprintf("unexpected PktType in pkt: %+v", pkt))
@@ -468,7 +468,7 @@ func (ep *endpoint) HandlePacket(nicID tcpip.NICID, localAddr tcpip.LinkAddress,
 				linkHeader = append(buffer.View(nil), pkt.LinkHeader().View()...)
 			}
 			combinedVV := linkHeader.ToVectorisedView()
-			combinedVV.Append(pkt.Data)
+			combinedVV.Append(pkt.Data().ExtractVV())
 			packet.data = combinedVV
 		} else {
 			packet.data = buffer.NewVectorisedView(pkt.Size(), pkt.Views())
diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
index fe8e9c751..2709be90c 100644
--- a/pkg/tcpip/transport/raw/endpoint.go
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -644,7 +644,7 @@ func (e *endpoint) HandlePacket(pkt *stack.PacketBuffer) {
 	} else {
 		combinedVV = append(buffer.View(nil), pkt.TransportHeader().View()...).ToVectorisedView()
 	}
-	combinedVV.Append(pkt.Data)
+	combinedVV.Append(pkt.Data().ExtractVV())
 	packet.data = combinedVV
 	packet.timestampNS = e.stack.Clock().NowNanoseconds()
 
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index 461b1a9d7..d1e452421 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -752,7 +752,7 @@ func buildTCPHdr(r *stack.Route, tf tcpFields, pkt *stack.PacketBuffer, gso *sta
 		// header and data and get the right sum of the TCP packet.
 		tcp.SetChecksum(xsum)
 	} else if r.RequiresTXTransportChecksum() {
-		xsum = header.ChecksumVV(pkt.Data, xsum)
+		xsum = header.ChecksumCombine(xsum, pkt.Data().AsRange().Checksum())
 		tcp.SetChecksum(^tcp.CalculateChecksum(xsum))
 	}
 }
@@ -786,7 +786,7 @@ func sendTCPBatch(r *stack.Route, tf tcpFields, data buffer.VectorisedView, gso
 		})
 		pkt.Hash = tf.txHash
 		pkt.Owner = owner
-		data.ReadToVV(&pkt.Data, packetSize)
+		pkt.Data().ReadFromVV(&data, packetSize)
 		buildTCPHdr(r, tf, pkt, gso)
 		tf.seq = tf.seq.Add(seqnum.Size(packetSize))
 		pkts.PushBack(pkt)
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 9ce6868df..687b9f459 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -2701,7 +2701,7 @@ func (e *endpoint) onICMPError(err tcpip.Error, transErr stack.TransportError, p
 			Cause: transErr,
 			// Linux passes the payload with the TCP header. We don't know if the TCP
 			// header even exists, it may not for fragmented packets.
-			Payload: pkt.Data.ToView(),
+			Payload: pkt.Data().AsRange().ToOwnedView(),
 			Dst: tcpip.FullAddress{
 				NIC:  pkt.NICID,
 				Addr: e.ID.RemoteAddress,
diff --git a/pkg/tcpip/transport/tcp/segment.go b/pkg/tcpip/transport/tcp/segment.go
index f27eef6a9..744382100 100644
--- a/pkg/tcpip/transport/tcp/segment.go
+++ b/pkg/tcpip/transport/tcp/segment.go
@@ -98,7 +98,7 @@ func newIncomingSegment(id stack.TransportEndpointID, pkt *stack.PacketBuffer) *
 		netProto: pkt.NetworkProtocolNumber,
 		nicID:    pkt.NICID,
 	}
-	s.data = pkt.Data.Clone(s.views[:])
+	s.data = pkt.Data().ExtractVV().Clone(s.views[:])
 	s.hdr = header.TCP(pkt.TransportHeader().View())
 	s.rcvdTime = time.Now()
 	s.dataMemSize = s.data.Size()
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 807df2bb5..b519afed1 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -1227,7 +1227,7 @@ func verifyChecksum(hdr header.UDP, pkt *stack.PacketBuffer) bool {
 		(hdr.Checksum() != 0 || pkt.NetworkProtocolNumber == header.IPv6ProtocolNumber) {
 		netHdr := pkt.Network()
 		xsum := header.PseudoHeaderChecksum(ProtocolNumber, netHdr.DestinationAddress(), netHdr.SourceAddress(), hdr.Length())
-		for _, v := range pkt.Data.Views() {
+		for _, v := range pkt.Data().Views() {
 			xsum = header.Checksum(v, xsum)
 		}
 		return hdr.CalculateChecksum(xsum) == 0xffff
@@ -1240,7 +1240,7 @@ func verifyChecksum(hdr header.UDP, pkt *stack.PacketBuffer) bool {
 func (e *endpoint) HandlePacket(id stack.TransportEndpointID, pkt *stack.PacketBuffer) {
 	// Get the header then trim it from the view.
 	hdr := header.UDP(pkt.TransportHeader().View())
-	if int(hdr.Length()) > pkt.Data.Size()+header.UDPMinimumSize {
+	if int(hdr.Length()) > pkt.Data().Size()+header.UDPMinimumSize {
 		// Malformed packet.
 		e.stack.Stats().UDP.MalformedPacketsReceived.Increment()
 		e.stats.ReceiveErrors.MalformedPacketsReceived.Increment()
@@ -1287,10 +1287,10 @@ func (e *endpoint) HandlePacket(id stack.TransportEndpointID, pkt *stack.PacketB
 			Addr: id.LocalAddress,
 			Port: header.UDP(hdr).DestinationPort(),
 		},
+		data: pkt.Data().ExtractVV(),
 	}
-	packet.data = pkt.Data
 	e.rcvList.PushBack(packet)
-	e.rcvBufSize += pkt.Data.Size()
+	e.rcvBufSize += packet.data.Size()
 
 	// Save any useful information from the network header to the packet.
 	switch pkt.NetworkProtocolNumber {
@@ -1327,7 +1327,7 @@ func (e *endpoint) onICMPError(err tcpip.Error, transErr stack.TransportError, p
 	if e.SocketOptions().GetRecvError() {
 		// Linux passes the payload without the UDP header.
 		var payload []byte
-		udp := header.UDP(pkt.Data.ToView())
+		udp := header.UDP(pkt.Data().AsRange().ToOwnedView())
 		if len(udp) >= header.UDPMinimumSize {
 			payload = udp.Payload()
 		}
diff --git a/pkg/tcpip/transport/udp/protocol.go b/pkg/tcpip/transport/udp/protocol.go
index 427fdd0c9..1171aeb79 100644
--- a/pkg/tcpip/transport/udp/protocol.go
+++ b/pkg/tcpip/transport/udp/protocol.go
@@ -80,7 +80,7 @@ func (*protocol) ParsePorts(v buffer.View) (src, dst uint16, err tcpip.Error) {
 // protocol but don't match any existing endpoint.
 func (p *protocol) HandleUnknownDestinationPacket(id stack.TransportEndpointID, pkt *stack.PacketBuffer) stack.UnknownDestinationPacketDisposition {
 	hdr := header.UDP(pkt.TransportHeader().View())
-	if int(hdr.Length()) > pkt.Data.Size()+header.UDPMinimumSize {
+	if int(hdr.Length()) > pkt.Data().Size()+header.UDPMinimumSize {
 		p.stack.Stats().UDP.MalformedPacketsReceived.Increment()
 		return stack.UnknownDestinationPacketMalformed
 	}