Only carry GSO options in the packet buffer

With this change, GSO options no longer needs to be passed around as
a function argument in the write path.

This change is done in preparation for a later change that defers
segmentation, and may change GSO options for a packet as it flows
down the stack.

Updates #170.

PiperOrigin-RevId: 369774872

1 files changed, 11 insertions, 11 deletions

diff --git a/pkg/tcpip/link/fdbased/endpoint.go b/pkg/tcpip/link/fdbased/endpoint.go
index 6be945116..feb79fe0e 100644
--- a/pkg/tcpip/link/fdbased/endpoint.go
+++ b/pkg/tcpip/link/fdbased/endpoint.go
@@ -433,7 +433,7 @@ func (e *endpoint) AddHeader(local, remote tcpip.LinkAddress, protocol tcpip.Net
 
 // WritePacket writes outbound packets to the file descriptor. If it is not
 // currently writable, the packet is dropped.
-func (e *endpoint) WritePacket(r stack.RouteInfo, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
+func (e *endpoint) WritePacket(r stack.RouteInfo, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) tcpip.Error {
 	if e.hdrSize > 0 {
 		e.AddHeader(r.LocalLinkAddress, r.RemoteLinkAddress, protocol, pkt)
 	}
@@ -443,23 +443,23 @@ func (e *endpoint) WritePacket(r stack.RouteInfo, gso *stack.GSO, protocol tcpip
 	fd := e.fds[pkt.Hash%uint32(len(e.fds))]
 	if e.Capabilities()&stack.CapabilityHardwareGSO != 0 {
 		vnetHdr := virtioNetHdr{}
-		if gso != nil {
+		if pkt.GSOOptions.Type != stack.GSONone {
 			vnetHdr.hdrLen = uint16(pkt.HeaderSize())
-			if gso.NeedsCsum {
+			if pkt.GSOOptions.NeedsCsum {
 				vnetHdr.flags = _VIRTIO_NET_HDR_F_NEEDS_CSUM
-				vnetHdr.csumStart = header.EthernetMinimumSize + gso.L3HdrLen
-				vnetHdr.csumOffset = gso.CsumOffset
+				vnetHdr.csumStart = header.EthernetMinimumSize + pkt.GSOOptions.L3HdrLen
+				vnetHdr.csumOffset = pkt.GSOOptions.CsumOffset
 			}
-			if gso.Type != stack.GSONone && uint16(pkt.Data().Size()) > gso.MSS {
-				switch gso.Type {
+			if pkt.GSOOptions.Type != stack.GSONone && uint16(pkt.Data().Size()) > pkt.GSOOptions.MSS {
+				switch pkt.GSOOptions.Type {
 				case stack.GSOTCPv4:
 					vnetHdr.gsoType = _VIRTIO_NET_HDR_GSO_TCPV4
 				case stack.GSOTCPv6:
 					vnetHdr.gsoType = _VIRTIO_NET_HDR_GSO_TCPV6
 				default:
-					panic(fmt.Sprintf("Unknown gso type: %v", gso.Type))
+					panic(fmt.Sprintf("Unknown gso type: %v", pkt.GSOOptions.Type))
 				}
-				vnetHdr.gsoSize = gso.MSS
+				vnetHdr.gsoSize = pkt.GSOOptions.MSS
 			}
 		}
 
@@ -484,7 +484,7 @@ func (e *endpoint) sendBatch(batchFD int, batch []*stack.PacketBuffer) (int, tcp
 		var vnetHdrBuf []byte
 		if e.Capabilities()&stack.CapabilityHardwareGSO != 0 {
 			vnetHdr := virtioNetHdr{}
-			if pkt.GSOOptions != nil {
+			if pkt.GSOOptions.Type != stack.GSONone {
 				vnetHdr.hdrLen = uint16(pkt.HeaderSize())
 				if pkt.GSOOptions.NeedsCsum {
 					vnetHdr.flags = _VIRTIO_NET_HDR_F_NEEDS_CSUM
@@ -540,7 +540,7 @@ func (e *endpoint) sendBatch(batchFD int, batch []*stack.PacketBuffer) (int, tcp
 //  - pkt.EgressRoute
 //  - pkt.GSOOptions
 //  - pkt.NetworkProtocolNumber
-func (e *endpoint) WritePackets(_ stack.RouteInfo, _ *stack.GSO, pkts stack.PacketBufferList, _ tcpip.NetworkProtocolNumber) (int, tcpip.Error) {
+func (e *endpoint) WritePackets(_ stack.RouteInfo, pkts stack.PacketBufferList, _ tcpip.NetworkProtocolNumber) (int, tcpip.Error) {
 	// Preallocate to avoid repeated reallocation as we append to batch.
 	// batchSz is 47 because when SWGSO is in use then a single 65KB TCP
 	// segment can get split into 46 segments of 1420 bytes and a single 216