routing: modify findPath to take into account additional edges

In this commit, we modify our path finding algorithm to take an
additional set of edges that are currently not known to us that are
used to temporarily extend our graph with during a payment session.
These edges should assist the sender of a payment in successfully
constructing a path to the destination.

These edges should usually represent private channels, as they are not
publicly advertised to the network for routing.

routing/pathfind_test.go

@@ -311,8 +311,10 @@ func TestBasicGraphPathFinding(t *testing.T) {
 
 	paymentAmt := lnwire.NewMSatFromSatoshis(100)
 	target := aliases["sophon"]
-	path, err := findPath(nil, graph, sourceNode, target, ignoredVertexes,
-		ignoredEdges, paymentAmt)
+	path, err := findPath(
+		nil, graph, nil, sourceNode, target, ignoredVertexes,
+		ignoredEdges, paymentAmt,
+	)
 	if err != nil {
 		t.Fatalf("unable to find path: %v", err)
 	}
@@ -451,8 +453,10 @@ func TestBasicGraphPathFinding(t *testing.T) {
 	// exist two possible paths in the graph, but the shorter (1 hop) path
 	// should be selected.
 	target = aliases["luoji"]
-	path, err = findPath(nil, graph, sourceNode, target, ignoredVertexes,
-		ignoredEdges, paymentAmt)
+	path, err = findPath(
+		nil, graph, nil, sourceNode, target, ignoredVertexes,
+		ignoredEdges, paymentAmt,
+	)
 	if err != nil {
 		t.Fatalf("unable to find route: %v", err)
 	}
@@ -572,8 +576,10 @@ func TestNewRoutePathTooLong(t *testing.T) {
 	// We start by confirming that routing a payment 20 hops away is possible.
 	// Alice should be able to find a valid route to ursula.
 	target := aliases["ursula"]
-	_, err = findPath(nil, graph, sourceNode, target, ignoredVertexes,
-		ignoredEdges, paymentAmt)
+	_, err = findPath(
+		nil, graph, nil, sourceNode, target, ignoredVertexes,
+		ignoredEdges, paymentAmt,
+	)
 	if err != nil {
 		t.Fatalf("path should have been found")
 	}
@@ -581,8 +587,10 @@ func TestNewRoutePathTooLong(t *testing.T) {
 	// Vincent is 21 hops away from Alice, and thus no valid route should be
 	// presented to Alice.
 	target = aliases["vincent"]
-	path, err := findPath(nil, graph, sourceNode, target, ignoredVertexes,
-		ignoredEdges, paymentAmt)
+	path, err := findPath(
+		nil, graph, nil, sourceNode, target, ignoredVertexes,
+		ignoredEdges, paymentAmt,
+	)
 	if err == nil {
 		t.Fatalf("should not have been able to find path, supposed to be "+
 			"greater than 20 hops, found route with %v hops",
@@ -621,8 +629,10 @@ func TestPathNotAvailable(t *testing.T) {
 		t.Fatalf("unable to parse pubkey: %v", err)
 	}
 
-	_, err = findPath(nil, graph, sourceNode, unknownNode, ignoredVertexes,
-		ignoredEdges, 100)
+	_, err = findPath(
+		nil, graph, nil, sourceNode, unknownNode, ignoredVertexes,
+		ignoredEdges, 100,
+	)
 	if !IsError(err, ErrNoPathFound) {
 		t.Fatalf("path shouldn't have been found: %v", err)
 	}
@@ -655,8 +665,10 @@ func TestPathInsufficientCapacity(t *testing.T) {
 	target := aliases["sophon"]
 
 	payAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
-	_, err = findPath(nil, graph, sourceNode, target, ignoredVertexes,
-		ignoredEdges, payAmt)
+	_, err = findPath(
+		nil, graph, nil, sourceNode, target, ignoredVertexes,
+		ignoredEdges, payAmt,
+	)
 	if !IsError(err, ErrNoPathFound) {
 		t.Fatalf("graph shouldn't be able to support payment: %v", err)
 	}
@@ -683,8 +695,10 @@ func TestRouteFailMinHTLC(t *testing.T) {
 	// attempt should fail.
 	target := aliases["songoku"]
 	payAmt := lnwire.MilliSatoshi(10)
-	_, err = findPath(nil, graph, sourceNode, target, ignoredVertexes,
-		ignoredEdges, payAmt)
+	_, err = findPath(
+		nil, graph, nil, sourceNode, target, ignoredVertexes,
+		ignoredEdges, payAmt,
+	)
 	if !IsError(err, ErrNoPathFound) {
 		t.Fatalf("graph shouldn't be able to support payment: %v", err)
 	}
@@ -711,8 +725,10 @@ func TestRouteFailDisabledEdge(t *testing.T) {
 	// succeed without issue, and return a single path.
 	target := aliases["songoku"]
 	payAmt := lnwire.NewMSatFromSatoshis(10000)
-	_, err = findPath(nil, graph, sourceNode, target, ignoredVertexes,
-		ignoredEdges, payAmt)
+	_, err = findPath(
+		nil, graph, nil, sourceNode, target, ignoredVertexes,
+		ignoredEdges, payAmt,
+	)
 	if err != nil {
 		t.Fatalf("unable to find path: %v", err)
 	}
@@ -730,8 +746,10 @@ func TestRouteFailDisabledEdge(t *testing.T) {
 
 	// Now, if we attempt to route through that edge, we should get a
 	// failure as it is no longer eligible.
-	_, err = findPath(nil, graph, sourceNode, target, ignoredVertexes,
-		ignoredEdges, payAmt)
+	_, err = findPath(
+		nil, graph, nil, sourceNode, target, ignoredVertexes,
+		ignoredEdges, payAmt,
+	)
 	if !IsError(err, ErrNoPathFound) {
 		t.Fatalf("graph shouldn't be able to support payment: %v", err)
 	}