Add a type to represent the NDP Prefix Information option.

This change is in preparation for NDP Prefix Discovery and SLAAC where the stack
will need to handle NDP Prefix Information options.

Tests: Test that given an NDP Prefix Information option buffer, correct values
are returned by the field getters.
PiperOrigin-RevId: 276594592

1 files changed, 71 insertions, 0 deletions

diff --git a/pkg/tcpip/header/ndp_test.go b/pkg/tcpip/header/ndp_test.go
index 0aac14f43..0bbf67a2b 100644
--- a/pkg/tcpip/header/ndp_test.go
+++ b/pkg/tcpip/header/ndp_test.go
@@ -197,3 +197,74 @@ func TestNDPTargetLinkLayerAddressOptionSerialize(t *testing.T) {
 		})
 	}
 }
+
+// TestNDPPrefixInformationOption tests the field getters and serialization of a
+// NDPPrefixInformation.
+func TestNDPPrefixInformationOption(t *testing.T) {
+	b := []byte{
+		43, 127,
+		1, 2, 3, 4,
+		5, 6, 7, 8,
+		5, 5, 5, 5,
+		9, 10, 11, 12,
+		13, 14, 15, 16,
+		17, 18, 19, 20,
+		21, 22, 23, 24,
+	}
+
+	targetBuf := []byte{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
+	opts := NDPOptions(targetBuf)
+	serializer := NDPOptionsSerializer{
+		NDPPrefixInformation(b),
+	}
+	opts.Serialize(serializer)
+	expectedBuf := []byte{
+		3, 4, 43, 64,
+		1, 2, 3, 4,
+		5, 6, 7, 8,
+		0, 0, 0, 0,
+		9, 10, 11, 12,
+		13, 14, 15, 16,
+		17, 18, 19, 20,
+		21, 22, 23, 24,
+	}
+	if !bytes.Equal(targetBuf, expectedBuf) {
+		t.Fatalf("got targetBuf = %x, want = %x", targetBuf, expectedBuf)
+	}
+
+	// First two bytes are the Type and Length fields, which are not part of
+	// the option body.
+	pi := NDPPrefixInformation(targetBuf[2:])
+
+	if got := pi.Type(); got != 3 {
+		t.Fatalf("got Type = %d, want = 3", got)
+	}
+
+	if got := pi.Length(); got != 30 {
+		t.Fatalf("got Length = %d, want = 30", got)
+	}
+
+	if got := pi.PrefixLength(); got != 43 {
+		t.Fatalf("got PrefixLength = %d, want = 43", got)
+	}
+
+	if pi.OnLinkFlag() {
+		t.Fatalf("got OnLinkFlag = true, want = false")
+	}
+
+	if !pi.AutonomousAddressConfigurationFlag() {
+		t.Fatalf("got AutonomousAddressConfigurationFlag = false, want = true")
+	}
+
+	if got, want := pi.ValidLifetime(), 16909060*time.Second; got != want {
+		t.Fatalf("got ValidLifetime = %d, want = %d", got, want)
+	}
+
+	if got, want := pi.PreferredLifetime(), 84281096*time.Second; got != want {
+		t.Fatalf("got PreferredLifetime = %d, want = %d", got, want)
+	}
+
+	if got, want := pi.Prefix(), tcpip.Address("\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18"); got != want {
+		t.Fatalf("got Prefix = %s, want = %s", got, want)
+	}
+}