Add support for Timestamp and RecordRoute IP options

IPv4 options extend the size of the IP header and have a basic known
format. The framework can process that format without needing to know
about every possible option. We can add more code to handle additional
option types as we need them. Bad options or mangled option entries
can result in ICMP Parameter Problem packets. The first types we
support are the Timestamp option and the Record Route option, included
in this change.

The options are processed at several points in the packet flow within
the Network stack, with slightly different requirements. The framework
includes a mechanism to control this at each point. Support has been
added for such points which are only present in upcoming CLs such as
during packet forwarding and fragmentation.

With this change, 'ping -R' and 'ping -T' work against gVisor and Fuchsia.

$ ping -R 192.168.1.2
PING 192.168.1.2 (192.168.1.2) 56(124) bytes of data.
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.990 ms
NOP
RR:     192.168.1.1
        192.168.1.2
        192.168.1.1

$ ping -T tsprespec 192.168.1.2 192.168.1.1 192.168.1.2
PING 192.168.1.2 (192.168.1.2) 56(124) bytes of data.
64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=1.20 ms
TS:     192.168.1.2    71486821 absolute
        192.168.1.1    746

Unit tests included for generic options, Timestamp options
and Record Route options.

PiperOrigin-RevId: 339379076

1 files changed, 16 insertions, 1 deletions

diff --git a/pkg/tcpip/checker/checker.go b/pkg/tcpip/checker/checker.go
index cf1145043..530f2ae2f 100644
--- a/pkg/tcpip/checker/checker.go
+++ b/pkg/tcpip/checker/checker.go
@@ -205,7 +205,7 @@ func IPv4Options(want []byte) NetworkChecker {
 		if !ok {
 			t.Fatalf("unexpected network header passed to checker, got = %T, want = header.IPv4", h[0])
 		}
-		options := ip.Options()
+		options := []byte(ip.Options())
 		// cmp.Diff does not consider nil slices equal to empty slices, but we do.
 		if len(want) == 0 && len(options) == 0 {
 			return
@@ -859,6 +859,21 @@ func ICMPv4Seq(want uint16) TransportChecker {
 	}
 }
 
+// ICMPv4Pointer creates a checker that checks the ICMPv4 Param Problem pointer.
+func ICMPv4Pointer(want uint8) TransportChecker {
+	return func(t *testing.T, h header.Transport) {
+		t.Helper()
+
+		icmpv4, ok := h.(header.ICMPv4)
+		if !ok {
+			t.Fatalf("unexpected transport header passed to checker, got = %T, want = header.ICMPv4", h)
+		}
+		if got := icmpv4.Pointer(); got != want {
+			t.Fatalf("unexpected ICMP Param Problem pointer, got = %d, want = %d", got, want)
+		}
+	}
+}
+
 // ICMPv4Checksum creates a checker that checks the ICMPv4 Checksum.
 // This assumes that the payload exactly makes up the rest of the slice.
 func ICMPv4Checksum() TransportChecker {