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

5 files changed, 29 insertions, 26 deletions

diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go
index 5bf7809e8..deb104837 100644
--- a/pkg/tcpip/network/ipv4/icmp.go
+++ b/pkg/tcpip/network/ipv4/icmp.go
@@ -137,7 +137,7 @@ func (e *endpoint) checkLocalAddress(addr tcpip.Address) bool {
 // is used to find out which transport endpoint must be notified about the ICMP
 // packet. We only expect the payload, not the enclosing ICMP packet.
 func (e *endpoint) handleControl(errInfo stack.TransportError, pkt *stack.PacketBuffer) {
-	h, ok := pkt.Data.PullUp(header.IPv4MinimumSize)
+	h, ok := pkt.Data().PullUp(header.IPv4MinimumSize)
 	if !ok {
 		return
 	}
@@ -156,7 +156,7 @@ func (e *endpoint) handleControl(errInfo stack.TransportError, pkt *stack.Packet
 	}
 
 	hlen := int(hdr.HeaderLength())
-	if pkt.Data.Size() < hlen || hdr.FragmentOffset() != 0 {
+	if pkt.Data().Size() < hlen || hdr.FragmentOffset() != 0 {
 		// We won't be able to handle this if it doesn't contain the
 		// full IPv4 header, or if it's a fragment not at offset 0
 		// (because it won't have the transport header).
@@ -164,7 +164,7 @@ func (e *endpoint) handleControl(errInfo stack.TransportError, pkt *stack.Packet
 	}
 
 	// Skip the ip header, then deliver the error.
-	pkt.Data.TrimFront(hlen)
+	pkt.Data().TrimFront(hlen)
 	p := hdr.TransportProtocol()
 	e.dispatcher.DeliverTransportError(srcAddr, hdr.DestinationAddress(), ProtocolNumber, p, errInfo, pkt)
 }
@@ -174,7 +174,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer) {
 	// TODO(gvisor.dev/issue/170): ICMP packets don't have their
 	// TransportHeader fields set. See icmp/protocol.go:protocol.Parse for a
 	// full explanation.
-	v, ok := pkt.Data.PullUp(header.ICMPv4MinimumSize)
+	v, ok := pkt.Data().PullUp(header.ICMPv4MinimumSize)
 	if !ok {
 		received.invalid.Increment()
 		return
@@ -182,7 +182,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer) {
 	h := header.ICMPv4(v)
 
 	// Only do in-stack processing if the checksum is correct.
-	if header.ChecksumVV(pkt.Data, 0 /* initial */) != 0xffff {
+	if pkt.Data().AsRange().Checksum() != 0xffff {
 		received.invalid.Increment()
 		// It's possible that a raw socket expects to receive this regardless
 		// of checksum errors. If it's an echo request we know it's safe because
@@ -253,7 +253,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer) {
 		// TODO(gvisor.dev/issue/4399): The copy may not be needed if there are no
 		// waiting endpoints. Consider moving responsibility for doing the copy to
 		// DeliverTransportPacket so that is is only done when needed.
-		replyData := pkt.Data.ToOwnedView()
+		replyData := pkt.Data().AsRange().ToOwnedView()
 		ipHdr := header.IPv4(pkt.NetworkHeader().View())
 		localAddressBroadcast := pkt.NetworkPacketInfo.LocalAddressBroadcast
 
@@ -336,7 +336,7 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer) {
 	case header.ICMPv4DstUnreachable:
 		received.dstUnreachable.Increment()
 
-		pkt.Data.TrimFront(header.ICMPv4MinimumSize)
+		pkt.Data().TrimFront(header.ICMPv4MinimumSize)
 		switch h.Code() {
 		case header.ICMPv4HostUnreachable:
 			e.handleControl(&icmpv4DestinationHostUnreachableSockError{}, pkt)
@@ -571,7 +571,7 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip
 		return nil
 	}
 
-	payloadLen := len(origIPHdr) + transportHeader.Size() + pkt.Data.Size()
+	payloadLen := len(origIPHdr) + transportHeader.Size() + pkt.Data().Size()
 	if payloadLen > available {
 		payloadLen = available
 	}
@@ -586,8 +586,11 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip
 	newHeader := append(buffer.View(nil), origIPHdr...)
 	newHeader = append(newHeader, transportHeader...)
 	payload := newHeader.ToVectorisedView()
-	payload.AppendView(pkt.Data.ToView())
-	payload.CapLength(payloadLen)
+	if dataCap := payloadLen - payload.Size(); dataCap > 0 {
+		payload.AppendView(pkt.Data().AsRange().Capped(dataCap).ToOwnedView())
+	} else {
+		payload.CapLength(payloadLen)
+	}
 
 	icmpPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
 		ReserveHeaderBytes: int(route.MaxHeaderLength()) + header.ICMPv4MinimumSize,
@@ -623,7 +626,7 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip
 	default:
 		panic(fmt.Sprintf("unsupported ICMP type %T", reason))
 	}
-	icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr, icmpPkt.Data))
+	icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr, icmpPkt.Data().AsRange().Checksum()))
 
 	if err := route.WritePacket(
 		nil, /* gso */
diff --git a/pkg/tcpip/network/ipv4/igmp.go b/pkg/tcpip/network/ipv4/igmp.go
index 0a15ae897..f3fc1c87e 100644
--- a/pkg/tcpip/network/ipv4/igmp.go
+++ b/pkg/tcpip/network/ipv4/igmp.go
@@ -197,7 +197,7 @@ func (igmp *igmpState) isPacketValidLocked(pkt *stack.PacketBuffer, messageType
 // Precondition: igmp.ep.mu must be locked.
 func (igmp *igmpState) handleIGMP(pkt *stack.PacketBuffer, hasRouterAlertOption bool) {
 	received := igmp.ep.stats.igmp.packetsReceived
-	headerView, ok := pkt.Data.PullUp(header.IGMPMinimumSize)
+	headerView, ok := pkt.Data().PullUp(header.IGMPMinimumSize)
 	if !ok {
 		received.invalid.Increment()
 		return
@@ -210,7 +210,7 @@ func (igmp *igmpState) handleIGMP(pkt *stack.PacketBuffer, hasRouterAlertOption
 	//   same set of octets, including the checksum field. If the result
 	//   is all 1 bits (-0 in 1's complement arithmetic), the check
 	//   succeeds.
-	if header.ChecksumVV(pkt.Data, 0 /* initial */) != 0xFFFF {
+	if pkt.Data().AsRange().Checksum() != 0xFFFF {
 		received.checksumErrors.Increment()
 		return
 	}
diff --git a/pkg/tcpip/network/ipv4/igmp_test.go b/pkg/tcpip/network/ipv4/igmp_test.go
index c5f68e411..e5e1b89cc 100644
--- a/pkg/tcpip/network/ipv4/igmp_test.go
+++ b/pkg/tcpip/network/ipv4/igmp_test.go
@@ -106,9 +106,9 @@ func createAndInjectIGMPPacket(e *channel.Endpoint, igmpType header.IGMPType, ma
 	igmp.SetGroupAddress(groupAddress)
 	igmp.SetChecksum(header.IGMPCalculateChecksum(igmp))
 
-	e.InjectInbound(ipv4.ProtocolNumber, &stack.PacketBuffer{
+	e.InjectInbound(ipv4.ProtocolNumber, stack.NewPacketBuffer(stack.PacketBufferOptions{
 		Data: buf.ToVectorisedView(),
-	})
+	}))
 }
 
 // TestIGMPV1Present tests the node's ability to fallback to V1 when a V1
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 4a429ea6c..cabe274d6 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -492,7 +492,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBuffer) tcpip.Error {
 	// The packet already has an IP header, but there are a few required
 	// checks.
-	h, ok := pkt.Data.PullUp(header.IPv4MinimumSize)
+	h, ok := pkt.Data().PullUp(header.IPv4MinimumSize)
 	if !ok {
 		return &tcpip.ErrMalformedHeader{}
 	}
@@ -502,14 +502,14 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
 		return &tcpip.ErrMalformedHeader{}
 	}
 
-	h, ok = pkt.Data.PullUp(int(hdrLen))
+	h, ok = pkt.Data().PullUp(int(hdrLen))
 	if !ok {
 		return &tcpip.ErrMalformedHeader{}
 	}
 	ip := header.IPv4(h)
 
 	// Always set the total length.
-	pktSize := pkt.Data.Size()
+	pktSize := pkt.Data().Size()
 	ip.SetTotalLength(uint16(pktSize))
 
 	// Set the source address when zero.
@@ -687,7 +687,7 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 	stats := e.stats
 
 	h := header.IPv4(pkt.NetworkHeader().View())
-	if !h.IsValid(pkt.Data.Size() + pkt.NetworkHeader().View().Size() + pkt.TransportHeader().View().Size()) {
+	if !h.IsValid(pkt.Data().Size() + pkt.NetworkHeader().View().Size() + pkt.TransportHeader().View().Size()) {
 		stats.ip.MalformedPacketsReceived.Increment()
 		return
 	}
@@ -765,7 +765,7 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 	}
 
 	if h.More() || h.FragmentOffset() != 0 {
-		if pkt.Data.Size()+pkt.TransportHeader().View().Size() == 0 {
+		if pkt.Data().Size()+pkt.TransportHeader().View().Size() == 0 {
 			// Drop the packet as it's marked as a fragment but has
 			// no payload.
 			stats.ip.MalformedPacketsReceived.Increment()
@@ -793,10 +793,10 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 		// maximum payload size.
 		//
 		// Note that this addition doesn't overflow even on 32bit architecture
-		// because pkt.Data.Size() should not exceed 65535 (the max IP datagram
+		// because pkt.Data().Size() should not exceed 65535 (the max IP datagram
 		// size). Otherwise the packet would've been rejected as invalid before
 		// reaching here.
-		if int(start)+pkt.Data.Size() > header.IPv4MaximumPayloadSize {
+		if int(start)+pkt.Data().Size() > header.IPv4MaximumPayloadSize {
 			stats.ip.MalformedPacketsReceived.Increment()
 			stats.ip.MalformedFragmentsReceived.Increment()
 			return
@@ -813,7 +813,7 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 				Protocol:    proto,
 			},
 			start,
-			start+uint16(pkt.Data.Size())-1,
+			start+uint16(pkt.Data().Size())-1,
 			h.More(),
 			proto,
 			pkt,
@@ -831,7 +831,7 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 
 		// The reassembler doesn't take care of fixing up the header, so we need
 		// to do it here.
-		h.SetTotalLength(uint16(pkt.Data.Size() + len((h))))
+		h.SetTotalLength(uint16(pkt.Data().Size() + len((h))))
 		h.SetFlagsFragmentOffset(0, 0)
 	}
 	stats.ip.PacketsDelivered.Increment()
@@ -1186,7 +1186,7 @@ func calculateNetworkMTU(linkMTU, networkHeaderSize uint32) (uint32, tcpip.Error
 }
 
 func packetMustBeFragmented(pkt *stack.PacketBuffer, networkMTU uint32, gso *stack.GSO) bool {
-	payload := pkt.TransportHeader().View().Size() + pkt.Data.Size()
+	payload := pkt.TransportHeader().View().Size() + pkt.Data().Size()
 	return (gso == nil || gso.Type == stack.GSONone) && uint32(payload) > networkMTU
 }
 
diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go
index dc4db6e5f..26d9696d7 100644
--- a/pkg/tcpip/network/ipv4/ipv4_test.go
+++ b/pkg/tcpip/network/ipv4/ipv4_test.go
@@ -1211,7 +1211,7 @@ func compareFragments(packets []*stack.PacketBuffer, sourcePacket *stack.PacketB
 			sourceCopy.SetFlagsFragmentOffset(sourceCopy.Flags()&^header.IPv4FlagMoreFragments, wantFragments[i].offset)
 		}
 		reassembledPayload.AppendView(packet.TransportHeader().View())
-		reassembledPayload.Append(packet.Data)
+		reassembledPayload.AppendView(packet.Data().AsRange().ToOwnedView())
 		// Clear out the checksum and length from the ip because we can't compare
 		// it.
 		sourceCopy.SetTotalLength(wantFragments[i].payloadSize + header.IPv4MinimumSize)