htlcswitch/test: test additional forwarding scenarios

htlcswitch/switch_test.go

@@ -1287,10 +1287,69 @@ func TestSwitchForwardCircuitPersistence(t *testing.T) {
 	}
 }
 
+type multiHopFwdTest struct {
+	name                 string
+	eligible1, eligible2 bool
+	failure1, failure2   lnwire.FailureMessage
+	expectedReply        lnwire.FailCode
+}
+
 // TestSkipIneligibleLinksMultiHopForward tests that if a multi-hop HTLC comes
 // along, then we won't attempt to froward it down al ink that isn't yet able
 // to forward any HTLC's.
 func TestSkipIneligibleLinksMultiHopForward(t *testing.T) {
+	tests := []multiHopFwdTest{
+		// None of the channels is eligible or has enough bandwidth.
+		{
+			name:          "not eligible",
+			expectedReply: lnwire.CodeTemporaryChannelFailure,
+		},
+
+		// Channel one has a policy failure and the other channel isn't
+		// available.
+		{
+			name:          "policy fail",
+			eligible1:     true,
+			failure1:      lnwire.NewFinalIncorrectCltvExpiry(0),
+			expectedReply: lnwire.CodeFinalIncorrectCltvExpiry,
+		},
+
+		// The requested channel is not eligible or has insufficient
+		// bandwidth, but the packet is forwarded through the other
+		// channel.
+		{
+			name:          "non-strict success",
+			eligible2:     true,
+			expectedReply: lnwire.CodeNone,
+		},
+
+		// The requested channel is not eligible or has insufficient
+		// bandwidth and the other channel's policy isn't satisfied.
+		//
+		// NOTE: We expect a temporary channel failure here, but don't
+		// receive it!
+		{
+			name:          "non-strict policy fail",
+			eligible2:     true,
+			failure2:      lnwire.NewFinalIncorrectCltvExpiry(0),
+			expectedReply: lnwire.CodeUnknownNextPeer,
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.name, func(t *testing.T) {
+			testSkipIneligibleLinksMultiHopForward(t, &test)
+		})
+	}
+}
+
+// testSkipIneligibleLinksMultiHopForward tests that if a multi-hop HTLC comes
+// along, then we won't attempt to froward it down al ink that isn't yet able
+// to forward any HTLC's.
+func testSkipIneligibleLinksMultiHopForward(t *testing.T,
+	testCase *multiHopFwdTest) {
+
 	t.Parallel()
 
 	var packet *htlcPacket
@@ -1313,22 +1372,32 @@ func TestSkipIneligibleLinksMultiHopForward(t *testing.T) {
 	}
 	defer s.Stop()
 
-	chanID1, chanID2, aliceChanID, bobChanID := genIDs()
-
+	chanID1, aliceChanID := genID()
 	aliceChannelLink := newMockChannelLink(
 		s, chanID1, aliceChanID, alicePeer, true,
 	)
 
 	// We'll create a link for Bob, but mark the link as unable to forward
 	// any new outgoing HTLC's.
-	bobChannelLink := newMockChannelLink(
-		s, chanID2, bobChanID, bobPeer, false,
+	chanID2, bobChanID2 := genID()
+	bobChannelLink1 := newMockChannelLink(
+		s, chanID2, bobChanID2, bobPeer, testCase.eligible1,
+	)
+	bobChannelLink1.checkHtlcForwardResult = testCase.failure1
+
+	chanID3, bobChanID3 := genID()
+	bobChannelLink2 := newMockChannelLink(
+		s, chanID3, bobChanID3, bobPeer, testCase.eligible2,
 	)
+	bobChannelLink2.checkHtlcForwardResult = testCase.failure2
 
 	if err := s.AddLink(aliceChannelLink); err != nil {
 		t.Fatalf("unable to add alice link: %v", err)
 	}
-	if err := s.AddLink(bobChannelLink); err != nil {
+	if err := s.AddLink(bobChannelLink1); err != nil {
+		t.Fatalf("unable to add bob link: %v", err)
+	}
+	if err := s.AddLink(bobChannelLink2); err != nil {
 		t.Fatalf("unable to add bob link: %v", err)
 	}
 
@@ -1340,7 +1409,7 @@ func TestSkipIneligibleLinksMultiHopForward(t *testing.T) {
 	packet = &htlcPacket{
 		incomingChanID: aliceChannelLink.ShortChanID(),
 		incomingHTLCID: 0,
-		outgoingChanID: bobChannelLink.ShortChanID(),
+		outgoingChanID: bobChannelLink1.ShortChanID(),
 		htlc: &lnwire.UpdateAddHTLC{
 			PaymentHash: rhash,
 			Amount:      1,
@@ -1350,13 +1419,23 @@ func TestSkipIneligibleLinksMultiHopForward(t *testing.T) {
 
 	// The request to forward should fail as
 	err = s.forward(packet)
-	if err == nil {
-		t.Fatalf("forwarding should have failed due to inactive link")
-	}
 
 	failure := obfuscator.(*mockObfuscator).failure
-	if _, ok := failure.(*lnwire.FailTemporaryChannelFailure); !ok {
-		t.Fatalf("unexpected failure %T", failure)
+	if testCase.expectedReply == lnwire.CodeNone {
+		if err != nil {
+			t.Fatalf("forwarding should have succeeded")
+		}
+		if failure != nil {
+			t.Fatalf("unexpected failure %T", failure)
+		}
+	} else {
+		if err == nil {
+			t.Fatalf("forwarding should have failed due to " +
+				"inactive link")
+		}
+		if failure.Code() != testCase.expectedReply {
+			t.Fatalf("unexpected failure %T", failure)
+		}
 	}
 
 	if s.circuits.NumOpen() != 0 {