netstack: Don't exclude length when a pseudo-header checksum is calculated

This is a preparation for GSO changes (cl/234508902).

RELNOTES[gofers]: Refactor checksum code to include length, which
it already did, but in a convoluted way. Should be a no-op.

PiperOrigin-RevId: 240460794
Change-Id: I537381bc670b5a9f5d70a87aa3eb7252e8f5ace2

4 files changed, 8 insertions, 12 deletions

diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index 4d352b23c..c4353718e 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -589,10 +589,10 @@ func sendTCP(r *stack.Route, id stack.TransportEndpointID, data buffer.Vectorise
 	// Only calculate the checksum if offloading isn't supported.
 	if r.Capabilities()&stack.CapabilityChecksumOffload == 0 {
 		length := uint16(hdr.UsedLength() + data.Size())
-		xsum := r.PseudoHeaderChecksum(ProtocolNumber)
+		xsum := r.PseudoHeaderChecksum(ProtocolNumber, length)
 		xsum = header.ChecksumVV(data, xsum)
 
-		tcp.SetChecksum(^tcp.CalculateChecksum(xsum, length))
+		tcp.SetChecksum(^tcp.CalculateChecksum(xsum))
 	}
 
 	r.Stats().TCP.SegmentsSent.Increment()
diff --git a/pkg/tcpip/transport/tcp/testing/context/context.go b/pkg/tcpip/transport/tcp/testing/context/context.go
index fb4ae4a1b..aa2a73829 100644
--- a/pkg/tcpip/transport/tcp/testing/context/context.go
+++ b/pkg/tcpip/transport/tcp/testing/context/context.go
@@ -332,9 +332,8 @@ func (c *Context) BuildSegment(payload []byte, h *Headers) buffer.VectorisedView
 	xsum = header.Checksum([]byte{0, uint8(tcp.ProtocolNumber)}, xsum)
 
 	// Calculate the TCP checksum and set it.
-	length := uint16(header.TCPMinimumSize + len(h.TCPOpts) + len(payload))
 	xsum = header.Checksum(payload, xsum)
-	t.SetChecksum(^t.CalculateChecksum(xsum, length))
+	t.SetChecksum(^t.CalculateChecksum(xsum))
 
 	// Inject packet.
 	return buf.ToVectorisedView()
@@ -487,9 +486,8 @@ func (c *Context) SendV6Packet(payload []byte, h *Headers) {
 	xsum = header.Checksum([]byte{0, uint8(tcp.ProtocolNumber)}, xsum)
 
 	// Calculate the TCP checksum and set it.
-	length := uint16(header.TCPMinimumSize + len(payload))
 	xsum = header.Checksum(payload, xsum)
-	t.SetChecksum(^t.CalculateChecksum(xsum, length))
+	t.SetChecksum(^t.CalculateChecksum(xsum))
 
 	// Inject packet.
 	c.linkEP.Inject(ipv6.ProtocolNumber, buf.ToVectorisedView())
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 82d7f80a3..b68ed8561 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -641,11 +641,11 @@ func sendUDP(r *stack.Route, data buffer.VectorisedView, localPort, remotePort u
 
 	// Only calculate the checksum if offloading isn't supported.
 	if r.Capabilities()&stack.CapabilityChecksumOffload == 0 {
-		xsum := r.PseudoHeaderChecksum(ProtocolNumber)
+		xsum := r.PseudoHeaderChecksum(ProtocolNumber, length)
 		for _, v := range data.Views() {
 			xsum = header.Checksum(v, xsum)
 		}
-		udp.SetChecksum(^udp.CalculateChecksum(xsum, length))
+		udp.SetChecksum(^udp.CalculateChecksum(xsum))
 	}
 
 	// Track count of packets sent.
diff --git a/pkg/tcpip/transport/udp/udp_test.go b/pkg/tcpip/transport/udp/udp_test.go
index 884a76b04..0d5871615 100644
--- a/pkg/tcpip/transport/udp/udp_test.go
+++ b/pkg/tcpip/transport/udp/udp_test.go
@@ -200,9 +200,8 @@ func (c *testContext) sendV6Packet(payload []byte, h *headers) {
 	xsum = header.Checksum([]byte{0, uint8(udp.ProtocolNumber)}, xsum)
 
 	// Calculate the UDP checksum and set it.
-	length := uint16(header.UDPMinimumSize + len(payload))
 	xsum = header.Checksum(payload, xsum)
-	u.SetChecksum(^u.CalculateChecksum(xsum, length))
+	u.SetChecksum(^u.CalculateChecksum(xsum))
 
 	// Inject packet.
 	c.linkEP.Inject(ipv6.ProtocolNumber, buf.ToVectorisedView())
@@ -239,9 +238,8 @@ func (c *testContext) sendPacket(payload []byte, h *headers) {
 	xsum = header.Checksum([]byte{0, uint8(udp.ProtocolNumber)}, xsum)
 
 	// Calculate the UDP checksum and set it.
-	length := uint16(header.UDPMinimumSize + len(payload))
 	xsum = header.Checksum(payload, xsum)
-	u.SetChecksum(^u.CalculateChecksum(xsum, length))
+	u.SetChecksum(^u.CalculateChecksum(xsum))
 
 	// Inject packet.
 	c.linkEP.Inject(ipv4.ProtocolNumber, buf.ToVectorisedView())