Merge release-20200219.0-134-gf56fe66 (automated)

2 files changed, 9 insertions, 5 deletions

diff --git a/pkg/tcpip/packet_buffer.go b/pkg/tcpip/packet_buffer.go
index ab24372e7..04852132c 100755
--- a/pkg/tcpip/packet_buffer.go
+++ b/pkg/tcpip/packet_buffer.go
@@ -39,8 +39,12 @@ type PacketBuffer struct {
 	// payload.
 	DataSize int
 
-	// Header holds the headers of outbound packets. As a packet is passed
-	// down the stack, each layer adds to Header.
+	// 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 buffer.Prependable
 
 	// These fields are used by both inbound and outbound packets. They
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index cd9202aed..e46bd86c6 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.
-	pkt.Header = buffer.NewPrependableFromView(pkt.Data.First())
-	pkt.Data.RemoveFirst()
+	// TODO(b/143425874): Decrease the TTL field in forwarded packets.
 
+	// 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