lnrpc+routing: fix issues with missing data in unmarshallRoute

In this commit the dependency of unmarshallRoute on edge policies being
available is removed. Edge policies may be unknown and reported as nil.
SendToRoute does not need the policies, but it does need pubkeys of the
route hops. In this commit, unmarshallRoute is modified so that it
takes the pubkeys from edgeInfo instead of channelEdgePolicy.

In addition to this, the route structure is simplified. No more connection
to the database at that point. Fees are determined based on incoming and
outgoing amounts.

routing/router.go

@@ -1274,7 +1274,7 @@ func pruneChannelFromRoutes(routes []*Route, skipChan uint64) []*Route {
 // fee information attached. The set of routes returned may be less than the
 // 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 [][]*ChannelHop,
+func pathsToFeeSortedRoutes(source Vertex, paths [][]*channeldb.ChannelEdgePolicy,
 	finalCLTVDelta uint16, amt, feeLimit lnwire.MilliSatoshi,
 	currentHeight uint32) ([]*Route, error) {
 
@@ -1461,19 +1461,13 @@ func generateSphinxPacket(route *Route, paymentHash []byte) ([]byte,
 	// in each hop.
 	nodes := make([]*btcec.PublicKey, len(route.Hops))
 	for i, hop := range route.Hops {
-		// We create a new instance of the public key to avoid possibly
-		// mutating the curve parameters, which are unset in a higher
-		// level in order to avoid spamming the logs.
-		nodePub, err := hop.Channel.Node.PubKey()
+		pub, err := btcec.ParsePubKey(hop.PubKeyBytes[:],
+			btcec.S256())
 		if err != nil {
 			return nil, nil, err
 		}
-		pub := btcec.PublicKey{
-			Curve: btcec.S256(),
-			X:     nodePub.X,
-			Y:     nodePub.Y,
-		}
-		nodes[i] = &pub
+
+		nodes[i] = pub
 	}
 
 	// Next we generate the per-hop payload which gives each node within
@@ -1736,7 +1730,7 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
 		// the payment. If this attempt fails, then we'll continue on
 		// to the next available route.
 		firstHop := lnwire.NewShortChanIDFromInt(
-			route.Hops[0].Channel.ChannelID,
+			route.Hops[0].ChannelID,
 		)
 		preImage, sendError = r.cfg.SendToSwitch(
 			firstHop, htlcAdd, circuit,