Process Hop-by-Hop header when forwarding IPv6 packets

Currently, we process IPv6 extension headers when receiving packets
but not when forwarding them. This is fine for the most part, with
with one exception: RFC 8200 requires that we process the
Hop-by-Hop headers even while forwarding packets.

This CL adds that support by invoking the Hop-by-hop logic performed
when receiving packets during forwarding as well.

PiperOrigin-RevId: 373145478

1 files changed, 11 insertions, 0 deletions

diff --git a/pkg/tcpip/checker/checker.go b/pkg/tcpip/checker/checker.go
index 12c39dfa3..18e6cc3cd 100644
--- a/pkg/tcpip/checker/checker.go
+++ b/pkg/tcpip/checker/checker.go
@@ -1607,6 +1607,17 @@ func IPv6RouterAlert(want header.IPv6RouterAlertValue) IPv6ExtHdrOptionChecker {
 	}
 }
 
+// IPv6UnknownOption validates that an extension header option is the
+// unknown header option.
+func IPv6UnknownOption() IPv6ExtHdrOptionChecker {
+	return func(t *testing.T, opt header.IPv6ExtHdrOption) {
+		_, ok := opt.(*header.IPv6UnknownExtHdrOption)
+		if !ok {
+			t.Errorf("got = %T, want = header.IPv6UnknownExtHdrOption", opt)
+		}
+	}
+}
+
 // IgnoreCmpPath returns a cmp.Option that ignores listed field paths.
 func IgnoreCmpPath(paths ...string) cmp.Option {
 	ignores := map[string]struct{}{}