netstack: use a proper network protocol to set gso.L3HdrLen

It is possible to create a listening socket which will accept
IPv4 and IPv6 connections. In this case, we set IPv6ProtocolNumber
for all accepted endpoints, even if they handle IPv4 connections.

This means that we can't use endpoint.netProto to set gso.L3HdrLen.

PiperOrigin-RevId: 244227948
Change-Id: I5e1863596cb9f3d216febacdb7dc75651882eef1

1 files changed, 9 insertions, 0 deletions

diff --git a/pkg/tcpip/transport/tcp/testing/context/context.go b/pkg/tcpip/transport/tcp/testing/context/context.go
index 8ac411b1d..6e2fed880 100644
--- a/pkg/tcpip/transport/tcp/testing/context/context.go
+++ b/pkg/tcpip/transport/tcp/testing/context/context.go
@@ -234,6 +234,10 @@ func (c *Context) GetPacket() []byte {
 		copy(b, p.Header)
 		copy(b[len(p.Header):], p.Payload)
 
+		if p.GSO != nil && p.GSO.L3HdrLen != header.IPv4MinimumSize {
+			c.t.Errorf("L3HdrLen %v (expected %v)", p.GSO.L3HdrLen, header.IPv4MinimumSize)
+		}
+
 		checker.IPv4(c.t, b, checker.SrcAddr(StackAddr), checker.DstAddr(TestAddr))
 		return b
 
@@ -956,3 +960,8 @@ func (c *Context) SACKEnabled() bool {
 	}
 	return bool(v)
 }
+
+// SetGSOEnabled enables or disables generic segmentation offload.
+func (c *Context) SetGSOEnabled(enable bool) {
+	c.linkEP.GSO = enable
+}