itest: add more tests related to inbound fees

Add tests for setting inbound fees in channel policies, including tests
where no inbound fees are set in the PolicyUpdateRequest.

itest/lnd_channel_policy_test.go

@@ -45,7 +45,9 @@ func testUpdateChannelPolicy(ht *lntest.HarnessTest) {
 	nodes := []*node.HarnessNode{alice, bob}
 
 	// Alice and Bob should see each other's ChannelUpdates, advertising the
-	// default routing policies.
+	// default routing policies. We do not currently set any inbound fees.
+	// The inbound base and inbound fee rate are advertised with a default
+	// of 0.
 	expectedPolicy := &lnrpc.RoutingPolicy{
 		FeeBaseMsat:      defaultFeeBase,
 		FeeRateMilliMsat: defaultFeeRate,
@@ -227,9 +229,9 @@ func testUpdateChannelPolicy(ht *lntest.HarnessTest) {
 	require.NoError(ht, err, "unable to receive payment stream")
 	require.Empty(ht, sendResp.PaymentError, "expected payment to succeed")
 
-	// With our little cluster set up, we'll update the fees and the max
-	// htlc size for the Bob side of the Alice->Bob channel, and make sure
-	// all nodes learn about it.
+	// With our little cluster set up, we'll update the outbound fees and
+	// the max htlc size for the Bob side of the Alice->Bob channel, and
+	// make sure all nodes learn about it. Inbound fees remain at 0.
 	baseFee := int64(1500)
 	feeRate := int64(12)
 	timeLockDelta := uint32(66)
@@ -298,17 +300,25 @@ func testUpdateChannelPolicy(ht *lntest.HarnessTest) {
 	feeRate = int64(123)
 	timeLockDelta = uint32(22)
 	maxHtlc *= 2
+	inboundBaseFee := int32(-400)
+	inboundFeeRatePpm := int32(-60)
 
 	expectedPolicy.FeeBaseMsat = baseFee
 	expectedPolicy.FeeRateMilliMsat = testFeeBase * feeRate
 	expectedPolicy.TimeLockDelta = timeLockDelta
 	expectedPolicy.MaxHtlcMsat = maxHtlc
+	expectedPolicy.InboundFeeBaseMsat = inboundBaseFee
+	expectedPolicy.InboundFeeRateMilliMsat = inboundFeeRatePpm
 
 	req = &lnrpc.PolicyUpdateRequest{
 		BaseFeeMsat:   baseFee,
 		FeeRate:       float64(feeRate),
 		TimeLockDelta: timeLockDelta,
 		MaxHtlcMsat:   maxHtlc,
+		InboundFee: &lnrpc.InboundFee{
+			BaseFeeMsat: inboundBaseFee,
+			FeeRatePpm:  inboundFeeRatePpm,
+		},
 	}
 	req.Scope = &lnrpc.PolicyUpdateRequest_Global{}
 	alice.RPC.UpdateChannelPolicy(req)
@@ -370,10 +380,13 @@ func testUpdateChannelPolicy(ht *lntest.HarnessTest) {
 		)
 	}
 
-	// Double the base fee and attach to the policy.
+	// Double the base fee and attach to the policy. Moreover, we set the
+	// inbound fee to nil and test that it does not change the propagated
+	// inbound fee.
 	baseFee1 := baseFee * 2
 	expectedPolicy.FeeBaseMsat = baseFee1
 	req.BaseFeeMsat = baseFee1
+	req.InboundFee = nil
 	assertAliceAndBob(req, expectedPolicy)
 
 	// Check that Carol has both heard the policy and updated it in her

itest/lnd_multi-hop-payments_test.go

@@ -74,8 +74,8 @@ func testMultiHopPayments(ht *lntest.HarnessTest) {
 	const aliceFeeRatePPM = 100000
 	updateChannelPolicy(
 		ht, alice, chanPointAlice, aliceBaseFeeSat*1000,
-		aliceFeeRatePPM, 0, 0, chainreg.DefaultBitcoinTimeLockDelta,
-		maxHtlc, carol,
+		aliceFeeRatePPM, 0, 0, false,
+		chainreg.DefaultBitcoinTimeLockDelta, maxHtlc, carol,
 	)
 
 	// Define a negative inbound fee for Alice, to verify that this is
@@ -85,9 +85,19 @@ func testMultiHopPayments(ht *lntest.HarnessTest) {
 		aliceInboundFeeRate     = -50000 // 5%
 	)
 
+	// We update the channel twice. The first time we set the inbound fee,
+	// the second time we don't. This is done to test whether the switch is
+	// still aware of the inbound fees.
 	updateChannelPolicy(
 		ht, alice, chanPointDave, 0, 0,
-		aliceInboundBaseFeeMsat, aliceInboundFeeRate,
+		aliceInboundBaseFeeMsat, aliceInboundFeeRate, true,
+		chainreg.DefaultBitcoinTimeLockDelta, maxHtlc,
+		dave,
+	)
+
+	updateChannelPolicy(
+		ht, alice, chanPointDave, 0, 0,
+		aliceInboundBaseFeeMsat, aliceInboundFeeRate, false,
 		chainreg.DefaultBitcoinTimeLockDelta, maxHtlc,
 		dave,
 	)
@@ -96,7 +106,7 @@ func testMultiHopPayments(ht *lntest.HarnessTest) {
 	const daveFeeRatePPM = 150000
 	updateChannelPolicy(
 		ht, dave, chanPointDave, daveBaseFeeSat*1000, daveFeeRatePPM,
-		0, 0,
+		0, 0, true,
 		chainreg.DefaultBitcoinTimeLockDelta, maxHtlc, carol,
 	)
 
@@ -236,8 +246,8 @@ func testMultiHopPayments(ht *lntest.HarnessTest) {
 //
 // NOTE: only used in current test.
 func updateChannelPolicy(ht *lntest.HarnessTest, hn *node.HarnessNode,
-	chanPoint *lnrpc.ChannelPoint, baseFee int64,
-	feeRate int64, inboundBaseFee, inboundFeeRate int32,
+	chanPoint *lnrpc.ChannelPoint, baseFee int64, feeRate int64,
+	inboundBaseFee, inboundFeeRate int32, updateInboundFee bool,
 	timeLockDelta uint32, maxHtlc uint64, listenerNode *node.HarnessNode) {
 
 	expectedPolicy := &lnrpc.RoutingPolicy{
@@ -250,6 +260,14 @@ func updateChannelPolicy(ht *lntest.HarnessTest, hn *node.HarnessNode,
 		InboundFeeRateMilliMsat: inboundFeeRate,
 	}
 
+	var inboundFee *lnrpc.InboundFee
+	if updateInboundFee {
+		inboundFee = &lnrpc.InboundFee{
+			BaseFeeMsat: inboundBaseFee,
+			FeeRatePpm:  inboundFeeRate,
+		}
+	}
+
 	updateFeeReq := &lnrpc.PolicyUpdateRequest{
 		BaseFeeMsat:   baseFee,
 		FeeRate:       float64(feeRate) / testFeeBase,
@@ -258,10 +276,7 @@ func updateChannelPolicy(ht *lntest.HarnessTest, hn *node.HarnessNode,
 			ChanPoint: chanPoint,
 		},
 		MaxHtlcMsat: maxHtlc,
-		InboundFee: &lnrpc.InboundFee{
-			BaseFeeMsat: inboundBaseFee,
-			FeeRatePpm:  inboundFeeRate,
-		},
+		InboundFee:  inboundFee,
 	}
 
 	hn.RPC.UpdateChannelPolicy(updateFeeReq)

lntest/node/watcher.go

@@ -681,6 +681,18 @@ func CheckChannelPolicy(policy, expectedPolicy *lnrpc.RoutingPolicy) error {
 		return fmt.Errorf("expected max htlc %v, got %v",
 			expectedPolicy.MaxHtlcMsat, policy.MaxHtlcMsat)
 	}
+	if policy.InboundFeeBaseMsat != expectedPolicy.InboundFeeBaseMsat {
+		return fmt.Errorf("expected inbound base fee %v, got %v",
+			expectedPolicy.InboundFeeBaseMsat,
+			policy.InboundFeeBaseMsat)
+	}
+	if policy.InboundFeeRateMilliMsat !=
+		expectedPolicy.InboundFeeRateMilliMsat {
+
+		return fmt.Errorf("expected inbound fee rate %v, got %v",
+			expectedPolicy.InboundFeeRateMilliMsat,
+			policy.InboundFeeRateMilliMsat)
+	}
 	if policy.Disabled != expectedPolicy.Disabled {
 		return errors.New("edge should be disabled but isn't")
 	}