Migrate to PacketHeader API for PacketBuffer.

Formerly, when a packet is constructed or parsed, all headers are set by the
client code. This almost always involved prepending to pk.Header buffer or
trimming pk.Data portion. This is known to prone to bugs, due to the complexity
and number of the invariants assumed across netstack to maintain.

In the new PacketHeader API, client will call Push()/Consume() method to
construct/parse an outgoing/incoming packet. All invariants, such as slicing
and trimming, are maintained by the API itself.

NewPacketBuffer() is introduced to create new PacketBuffer. Zero value is no
longer valid.

PacketBuffer now assumes the packet is a concatenation of following portions:
* LinkHeader
* NetworkHeader
* TransportHeader
* Data
Any of them could be empty, or zero-length.

PiperOrigin-RevId: 326507688

1 files changed, 20 insertions, 12 deletions

diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go
index 5174e639c..93567806b 100644
--- a/pkg/tcpip/stack/ndp.go
+++ b/pkg/tcpip/stack/ndp.go
@@ -746,12 +746,16 @@ func (ndp *ndpState) sendDADPacket(addr tcpip.Address, ref *referencedNetworkEnd
 		panic(fmt.Sprintf("ndp: route resolution not immediate for route to send NDP NS for DAD (%s -> %s on NIC(%d))", header.IPv6Any, snmc, ndp.nic.ID()))
 	}
 
-	hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv6NeighborSolicitMinimumSize)
-	pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborSolicitMinimumSize))
-	pkt.SetType(header.ICMPv6NeighborSolicit)
-	ns := header.NDPNeighborSolicit(pkt.NDPPayload())
+	icmpData := header.ICMPv6(buffer.NewView(header.ICMPv6NeighborSolicitMinimumSize))
+	icmpData.SetType(header.ICMPv6NeighborSolicit)
+	ns := header.NDPNeighborSolicit(icmpData.NDPPayload())
 	ns.SetTargetAddress(addr)
-	pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
+	icmpData.SetChecksum(header.ICMPv6Checksum(icmpData, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
+
+	pkt := NewPacketBuffer(PacketBufferOptions{
+		ReserveHeaderBytes: int(r.MaxHeaderLength()),
+		Data:               buffer.View(icmpData).ToVectorisedView(),
+	})
 
 	sent := r.Stats().ICMP.V6PacketsSent
 	if err := r.WritePacket(nil,
@@ -759,7 +763,7 @@ func (ndp *ndpState) sendDADPacket(addr tcpip.Address, ref *referencedNetworkEnd
 			Protocol: header.ICMPv6ProtocolNumber,
 			TTL:      header.NDPHopLimit,
 			TOS:      DefaultTOS,
-		}, &PacketBuffer{Header: hdr},
+		}, pkt,
 	); err != nil {
 		sent.Dropped.Increment()
 		return err
@@ -1897,12 +1901,16 @@ func (ndp *ndpState) startSolicitingRouters() {
 			}
 		}
 		payloadSize := header.ICMPv6HeaderSize + header.NDPRSMinimumSize + int(optsSerializer.Length())
-		hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + payloadSize)
-		pkt := header.ICMPv6(hdr.Prepend(payloadSize))
-		pkt.SetType(header.ICMPv6RouterSolicit)
-		rs := header.NDPRouterSolicit(pkt.NDPPayload())
+		icmpData := header.ICMPv6(buffer.NewView(payloadSize))
+		icmpData.SetType(header.ICMPv6RouterSolicit)
+		rs := header.NDPRouterSolicit(icmpData.NDPPayload())
 		rs.Options().Serialize(optsSerializer)
-		pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
+		icmpData.SetChecksum(header.ICMPv6Checksum(icmpData, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{}))
+
+		pkt := NewPacketBuffer(PacketBufferOptions{
+			ReserveHeaderBytes: int(r.MaxHeaderLength()),
+			Data:               buffer.View(icmpData).ToVectorisedView(),
+		})
 
 		sent := r.Stats().ICMP.V6PacketsSent
 		if err := r.WritePacket(nil,
@@ -1910,7 +1918,7 @@ func (ndp *ndpState) startSolicitingRouters() {
 				Protocol: header.ICMPv6ProtocolNumber,
 				TTL:      header.NDPHopLimit,
 				TOS:      DefaultTOS,
-			}, &PacketBuffer{Header: hdr},
+			}, pkt,
 		); err != nil {
 			sent.Dropped.Increment()
 			log.Printf("startSolicitingRouters: error writing NDP router solicit message on NIC(%d); err = %s", ndp.nic.ID(), err)