Update {LinkEndpoint,NetworkEndpoint}#WritePacket to take a VectorisedView

Makes it possible to avoid copying or allocating in cases where DeliverNetworkPacket (rx)
needs to turn around and call WritePacket (tx) with its VectorisedView.

Also removes the restriction on having VectorisedViews with multiple views in the write path.

PiperOrigin-RevId: 211728717
Change-Id: Ie03a65ecb4e28bd15ebdb9c69f05eced18fdfcff

1 files changed, 6 insertions, 6 deletions

diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 6a12c2f08..283379a28 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -328,7 +328,8 @@ func (e *endpoint) Write(p tcpip.Payload, opts tcpip.WriteOptions) (uintptr, *tc
 		return 0, err
 	}
 
-	if err := sendUDP(route, v, e.id.LocalPort, dstPort); err != nil {
+	vv := buffer.NewVectorisedView(len(v), []buffer.View{v})
+	if err := sendUDP(route, vv, e.id.LocalPort, dstPort); err != nil {
 		return 0, err
 	}
 	return uintptr(len(v)), nil
@@ -426,14 +427,14 @@ func (e *endpoint) GetSockOpt(opt interface{}) *tcpip.Error {
 
 // sendUDP sends a UDP segment via the provided network endpoint and under the
 // provided identity.
-func sendUDP(r *stack.Route, data buffer.View, localPort, remotePort uint16) *tcpip.Error {
+func sendUDP(r *stack.Route, data buffer.VectorisedView, localPort, remotePort uint16) *tcpip.Error {
 	// Allocate a buffer for the UDP header.
 	hdr := buffer.NewPrependable(header.UDPMinimumSize + int(r.MaxHeaderLength()))
 
 	// Initialize the header.
 	udp := header.UDP(hdr.Prepend(header.UDPMinimumSize))
 
-	length := uint16(hdr.UsedLength()) + uint16(len(data))
+	length := uint16(hdr.UsedLength() + data.Size())
 	udp.Encode(&header.UDPFields{
 		SrcPort: localPort,
 		DstPort: remotePort,
@@ -443,10 +444,9 @@ func sendUDP(r *stack.Route, data buffer.View, localPort, remotePort uint16) *tc
 	// Only calculate the checksum if offloading isn't supported.
 	if r.Capabilities()&stack.CapabilityChecksumOffload == 0 {
 		xsum := r.PseudoHeaderChecksum(ProtocolNumber)
-		if data != nil {
-			xsum = header.Checksum(data, xsum)
+		for _, v := range data.Views() {
+			xsum = header.Checksum(v, xsum)
 		}
-
 		udp.SetChecksum(^udp.CalculateChecksum(xsum, length))
 	}