routing: add source parameter to query routes

This commit allows execution of QueryRoutes from any source node.
Previously this was restricted to only the self node.

lnrpc/rpc.proto

@@ -1490,6 +1490,12 @@ message QueryRoutesRequest {
     A list of edges to ignore during path finding.
     */
     repeated EdgeLocator ignored_edges = 7;
+
+    /**
+    The source node where the request route should originated from. If empty,
+    self is assumed.
+    */
+    string source_pub_key = 8;
 }
 
 message EdgeLocator {

lnrpc/rpc.swagger.json

@@ -604,6 +604,13 @@
               "type": "string",
               "format": "byte"
             }
+          },
+          {
+            "name": "source_pub_key",
+            "description": "*\nThe source node where the request route should originated from. If empty,\nself is assumed.",
+            "in": "query",
+            "required": false,
+            "type": "string"
           }
         ],
         "tags": [

routing/pathfind_test.go

@@ -1712,7 +1712,7 @@ func TestPathFindSpecExample(t *testing.T) {
 	carol := ctx.aliases["C"]
 	const amt lnwire.MilliSatoshi = 4999999
 	routes, err := ctx.router.FindRoutes(
-		carol, amt, noRestrictions, 100,
+		bobNode.PubKeyBytes, carol, amt, noRestrictions, 100,
 	)
 	if err != nil {
 		t.Fatalf("unable to find route: %v", err)
@@ -1779,7 +1779,7 @@ func TestPathFindSpecExample(t *testing.T) {
 	// We'll now request a route from A -> B -> C.
 	ctx.router.routeCache = make(map[routeTuple][]*Route)
 	routes, err = ctx.router.FindRoutes(
-		carol, amt, noRestrictions, 100,
+		source.PubKeyBytes, carol, amt, noRestrictions, 100,
 	)
 	if err != nil {
 		t.Fatalf("unable to find routes: %v", err)

routing/router.go

@@ -1325,9 +1325,9 @@ func pathsToFeeSortedRoutes(source Vertex, paths [][]*channeldb.ChannelEdgePolic
 // the required fee and time lock values running backwards along the route. The
 // route that will be ranked the highest is the one with the lowest cumulative
 // fee along the route.
-func (r *ChannelRouter) FindRoutes(target Vertex, amt lnwire.MilliSatoshi, 
-	restrictions *RestrictParams, numPaths uint32, finalExpiry ...uint16) (
-		[]*Route, error) {
+func (r *ChannelRouter) FindRoutes(source, target Vertex,
+	amt lnwire.MilliSatoshi, restrictions *RestrictParams, numPaths uint32,
+	finalExpiry ...uint16) ([]*Route, error) {
 
 	var finalCLTVDelta uint16
 	if len(finalExpiry) == 0 {
@@ -1394,8 +1394,8 @@ func (r *ChannelRouter) FindRoutes(target Vertex, amt lnwire.MilliSatoshi,
 	// we'll execute our KSP algorithm to find the k-shortest paths from
 	// our source to the destination.
 	shortestPaths, err := findPaths(
-		tx, r.cfg.Graph, r.selfNode.PubKeyBytes, target, amt, 
-		restrictions, numPaths, bandwidthHints,
+		tx, r.cfg.Graph, source, target, amt, restrictions,
+		numPaths, bandwidthHints,
 	)
 	if err != nil {
 		tx.Rollback()

routing/router_test.go

@@ -184,6 +184,7 @@ func TestFindRoutesFeeSorting(t *testing.T) {
 	paymentAmt := lnwire.NewMSatFromSatoshis(100)
 	target := ctx.aliases["luoji"]
 	routes, err := ctx.router.FindRoutes(
+		ctx.router.selfNode.PubKeyBytes,
 		target, paymentAmt, noRestrictions, defaultNumRoutes,
 		DefaultFinalCLTVDelta,
 	)
@@ -245,6 +246,7 @@ func TestFindRoutesWithFeeLimit(t *testing.T) {
 	}
 
 	routes, err := ctx.router.FindRoutes(
+		ctx.router.selfNode.PubKeyBytes,
 		target, paymentAmt, restrictions, defaultNumRoutes,
 		DefaultFinalCLTVDelta,
 	)
@@ -1341,6 +1343,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 	var targetPubKeyBytes Vertex
 	copy(targetPubKeyBytes[:], targetNode.SerializeCompressed())
 	routes, err := ctx.router.FindRoutes(
+		ctx.router.selfNode.PubKeyBytes,
 		targetPubKeyBytes, paymentAmt, noRestrictions, defaultNumRoutes,
 		DefaultFinalCLTVDelta,
 	)
@@ -1386,6 +1389,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 	// Should still be able to find the routes, and the info should be
 	// updated.
 	routes, err = ctx.router.FindRoutes(
+		ctx.router.selfNode.PubKeyBytes,
 		targetPubKeyBytes, paymentAmt, noRestrictions, defaultNumRoutes,
 		DefaultFinalCLTVDelta,
 	)

rpcserver.go

@@ -3997,18 +3997,48 @@ func (r *rpcServer) GetNodeInfo(ctx context.Context,
 func (r *rpcServer) QueryRoutes(ctx context.Context,
 	in *lnrpc.QueryRoutesRequest) (*lnrpc.QueryRoutesResponse, error) {
 
+	parsePubKey := func(key string) (routing.Vertex, error) {
+		pubKeyBytes, err := hex.DecodeString(key)
+		if err != nil {
+			return routing.Vertex{}, err
+		}
 
-	pubKeyBytes, err := hex.DecodeString(in.PubKey)
+		if len(pubKeyBytes) != 33 {
+			return routing.Vertex{},
+				errors.New("invalid key length")
+		}
+
+		var v routing.Vertex
+		copy(v[:], pubKeyBytes)
+
+		return v, nil
+	}
+
+	// Parse the hex-encoded source and target public keys into full public
+	// key objects we can properly manipulate.
+	targetPubKey, err := parsePubKey(in.PubKey)
 	if err != nil {
 		return nil, err
 	}
 
-	if len(pubKeyBytes) != 33 {
-		return nil, errors.New("invalid key length")
-	}
+	var sourcePubKey routing.Vertex
+	if in.SourcePubKey != "" {
+		var err error
+		sourcePubKey, err = parsePubKey(in.SourcePubKey)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		// If no source is specified, use self.
 
-	var pubKey routing.Vertex
-	copy(pubKey[:], pubKeyBytes)
+		channelGraph := r.server.chanDB.ChannelGraph()
+		selfNode, err := channelGraph.SourceNode()
+		if err != nil {
+			return nil, err
+		}
+
+		sourcePubKey = selfNode.PubKeyBytes
+	}
 
 	// Currently, within the bootstrap phase of the network, we limit the
 	// largest payment size allotted to (2^32) - 1 mSAT or 4.29 million
@@ -4066,11 +4096,11 @@ func (r *rpcServer) QueryRoutes(ctx context.Context,
 
 	if in.FinalCltvDelta == 0 {
 		routes, findErr = r.server.chanRouter.FindRoutes(
-			pubKey, amtMSat, restrictions, numRoutesIn,
+			sourcePubKey, targetPubKey, amtMSat, restrictions, numRoutesIn,
 		)
 	} else {
 		routes, findErr = r.server.chanRouter.FindRoutes(
-			pubKey, amtMSat, restrictions, numRoutesIn,
+			sourcePubKey, targetPubKey, amtMSat, restrictions, numRoutesIn,
 			uint16(in.FinalCltvDelta),
 		)
 	}