routing: remove redundant fee limit check in newRoute

This check was a left over from when the fee limit wasn't checked yet in
the path finding algorithm.

routing/pathfind.go

@@ -210,7 +210,7 @@ func (r *Route) ToHopPayloads() []sphinx.HopData {
 //
 // NOTE: The passed slice of ChannelHops MUST be sorted in forward order: from
 // the source to the target node of the path finding attempt.
-func newRoute(amtToSend, feeLimit lnwire.MilliSatoshi, sourceVertex Vertex,
+func newRoute(amtToSend lnwire.MilliSatoshi, sourceVertex Vertex,
 	pathEdges []*channeldb.ChannelEdgePolicy, currentHeight uint32,
 	finalCLTVDelta uint16) (*Route, error) {
 
@@ -310,13 +310,6 @@ func newRoute(amtToSend, feeLimit lnwire.MilliSatoshi, sourceVertex Vertex,
 		return nil, err
 	}
 
-	// Invalidate this route if its total fees exceed our fee limit.
-	if newRoute.TotalFees > feeLimit {
-		err := fmt.Sprintf("total route fees exceeded fee "+
-			"limit of %v", feeLimit)
-		return nil, newErrf(ErrFeeLimitExceeded, err)
-	}
-
 	return newRoute, nil
 }
 

routing/pathfind_test.go

@@ -623,7 +623,7 @@ func TestFindLowestFeePath(t *testing.T) {
 		t.Fatalf("unable to find path: %v", err)
 	}
 	route, err := newRoute(
-		paymentAmt, infinity, sourceVertex, path, startingHeight,
+		paymentAmt, sourceVertex, path, startingHeight,
 		finalHopCLTV)
 	if err != nil {
 		t.Fatalf("unable to create path: %v", err)
@@ -776,7 +776,7 @@ func testBasicGraphPathFindingCase(t *testing.T, graphInstance *testGraphInstanc
 	}
 
 	route, err := newRoute(
-		paymentAmt, test.feeLimit, sourceVertex, path, startingHeight,
+		paymentAmt, sourceVertex, path, startingHeight,
 		finalHopCLTV,
 	)
 	if err != nil {
@@ -1056,8 +1056,6 @@ func TestNewRoute(t *testing.T) {
 		// expectedErrorCode indicates the expected error code when
 		// expectError is true.
 		expectedErrorCode errorCode
-
-		feeLimit lnwire.MilliSatoshi
 	}{
 		{
 			// For a single hop payment, no fees are expected to be paid.
@@ -1070,7 +1068,6 @@ func TestNewRoute(t *testing.T) {
 			expectedTimeLocks:     []uint32{1},
 			expectedTotalAmount:   100000,
 			expectedTotalTimeLock: 1,
-			feeLimit:              noFeeLimit,
 		}, {
 			// For a two hop payment, only the fee for the first hop
 			// needs to be paid. The destination hop does not require
@@ -1085,7 +1082,6 @@ func TestNewRoute(t *testing.T) {
 			expectedTimeLocks:     []uint32{1, 1},
 			expectedTotalAmount:   100130,
 			expectedTotalTimeLock: 6,
-			feeLimit:              noFeeLimit,
 		}, {
 			// A three hop payment where the first and second hop
 			// will both charge 1 msat. The fee for the first hop
@@ -1103,7 +1099,6 @@ func TestNewRoute(t *testing.T) {
 			expectedTotalAmount:   100002,
 			expectedTimeLocks:     []uint32{4, 1, 1},
 			expectedTotalTimeLock: 9,
-			feeLimit:              noFeeLimit,
 		}, {
 			// A three hop payment where the fee of the first hop
 			// is slightly higher (11) than the fee at the second hop,
@@ -1119,7 +1114,6 @@ func TestNewRoute(t *testing.T) {
 			expectedTotalAmount:   102010,
 			expectedTimeLocks:     []uint32{4, 1, 1},
 			expectedTotalTimeLock: 9,
-			feeLimit:              noFeeLimit,
 		}, {
 			// A three hop payment where the fee policies of the first and
 			// second hop are just high enough to show the fee carry over
@@ -1141,53 +1135,6 @@ func TestNewRoute(t *testing.T) {
 			expectedTotalAmount:   101101,
 			expectedTimeLocks:     []uint32{4, 1, 1},
 			expectedTotalTimeLock: 9,
-			feeLimit:              noFeeLimit,
-		},
-		// Check fee limit behaviour
-		{
-			name:          "two hop success with fee limit (greater)",
-			paymentAmount: 100000,
-			hops: []*channeldb.ChannelEdgePolicy{
-				createHop(0, 1000, 1000000, 144),
-				createHop(0, 1000, 1000000, 144),
-			},
-			expectedTotalAmount:   100100,
-			expectedFees:          []lnwire.MilliSatoshi{100, 0},
-			expectedTimeLocks:     []uint32{1, 1},
-			expectedTotalTimeLock: 145,
-			feeLimit:              150,
-		}, {
-			name:          "two hop success with fee limit (equal)",
-			paymentAmount: 100000,
-			hops: []*channeldb.ChannelEdgePolicy{
-				createHop(0, 1000, 1000000, 144),
-				createHop(0, 1000, 1000000, 144),
-			},
-			expectedTotalAmount:   100100,
-			expectedFees:          []lnwire.MilliSatoshi{100, 0},
-			expectedTimeLocks:     []uint32{1, 1},
-			expectedTotalTimeLock: 145,
-			feeLimit:              100,
-		}, {
-			name:          "two hop failure with fee limit (smaller)",
-			paymentAmount: 100000,
-			hops: []*channeldb.ChannelEdgePolicy{
-				createHop(0, 1000, 1000000, 144),
-				createHop(0, 1000, 1000000, 144),
-			},
-			feeLimit:          50,
-			expectError:       true,
-			expectedErrorCode: ErrFeeLimitExceeded,
-		}, {
-			name:          "two hop failure with fee limit (zero)",
-			paymentAmount: 100000,
-			hops: []*channeldb.ChannelEdgePolicy{
-				createHop(0, 1000, 1000000, 144),
-				createHop(0, 1000, 1000000, 144),
-			},
-			feeLimit:          0,
-			expectError:       true,
-			expectedErrorCode: ErrFeeLimitExceeded,
 		}}
 
 	for _, testCase := range testCases {
@@ -1238,7 +1185,6 @@ func TestNewRoute(t *testing.T) {
 
 		t.Run(testCase.name, func(t *testing.T) {
 			route, err := newRoute(testCase.paymentAmount,
-				testCase.feeLimit,
 				sourceVertex, testCase.hops, startingHeight,
 				finalHopCLTV)
 
@@ -2106,7 +2052,7 @@ func TestRestrictOutgoingChannel(t *testing.T) {
 		t.Fatalf("unable to find path: %v", err)
 	}
 	route, err := newRoute(
-		paymentAmt, infinity, sourceVertex, path, startingHeight,
+		paymentAmt, sourceVertex, path, startingHeight,
 		finalHopCLTV,
 	)
 	if err != nil {

routing/payment_session.go

@@ -163,8 +163,7 @@ func (p *paymentSession) RequestRoute(payment *LightningPayment,
 	// a route by applying the time-lock and fee requirements.
 	sourceVertex := Vertex(p.mc.selfNode.PubKeyBytes)
 	route, err := newRoute(
-		payment.Amount, payment.FeeLimit, sourceVertex, path, height,
-		finalCltvDelta,
+		payment.Amount, sourceVertex, path, height, finalCltvDelta,
 	)
 	if err != nil {
 		// TODO(roasbeef): return which edge/vertex didn't work

routing/router.go

@@ -1266,7 +1266,7 @@ type routingMsg struct {
 // initial set of paths as it's possible we drop a route if it can't handle the
 // total payment flow after fees are calculated.
 func pathsToFeeSortedRoutes(source Vertex, paths [][]*channeldb.ChannelEdgePolicy,
-	finalCLTVDelta uint16, amt, feeLimit lnwire.MilliSatoshi,
+	finalCLTVDelta uint16, amt lnwire.MilliSatoshi,
 	currentHeight uint32) ([]*Route, error) {
 
 	validRoutes := make([]*Route, 0, len(paths))
@@ -1275,8 +1275,7 @@ func pathsToFeeSortedRoutes(source Vertex, paths [][]*channeldb.ChannelEdgePolic
 		// hop in the path as it contains a "self-hop" that is inserted
 		// by our KSP algorithm.
 		route, err := newRoute(
-			amt, feeLimit, source, path[1:], currentHeight,
-			finalCLTVDelta,
+			amt, source, path[1:], currentHeight,			finalCLTVDelta,
 		)
 		if err != nil {
 			// TODO(roasbeef): report straw breaking edge?
@@ -1412,7 +1411,7 @@ func (r *ChannelRouter) FindRoutes(target *btcec.PublicKey,
 	// factored in.
 	sourceVertex := Vertex(r.selfNode.PubKeyBytes)
 	validRoutes, err := pathsToFeeSortedRoutes(
-		sourceVertex, shortestPaths, finalCLTVDelta, amt, feeLimit,
+		sourceVertex, shortestPaths, finalCLTVDelta, amt, 
 		uint32(currentHeight),
 	)
 	if err != nil {