SendToRoute with routing hints (#1325)

SendToRoute previously didn't accept invoice routing hints.
This was a limitation when paying a wallet invoice.
Invoice hints are now correctly taken into account.

eclair-core/src/main/scala/fr/acinq/eclair/payment/send/PaymentInitiator.scala

@@ -112,12 +112,12 @@ class PaymentInitiator(nodeParams: NodeParams, router: ActorRef, relayer: ActorR
           val trampolineSecret = r.trampolineSecret.getOrElse(randomBytes32)
           sender ! SendPaymentToRouteResponse(paymentId, parentPaymentId, Some(trampolineSecret))
           val (trampolineAmount, trampolineExpiry, trampolineOnion) = buildTrampolinePayment(SendTrampolinePaymentRequest(r.recipientAmount, r.paymentRequest, trampoline, Seq((r.trampolineFees, r.trampolineExpiryDelta)), r.finalExpiryDelta), r.trampolineFees, r.trampolineExpiryDelta)
-          payFsm forward SendPaymentToRoute(r.route, Onion.createMultiPartPayload(r.amount, trampolineAmount, trampolineExpiry, trampolineSecret, Seq(OnionTlv.TrampolineOnion(trampolineOnion))))
+          payFsm forward SendPaymentToRoute(r.route, Onion.createMultiPartPayload(r.amount, trampolineAmount, trampolineExpiry, trampolineSecret, Seq(OnionTlv.TrampolineOnion(trampolineOnion))), r.paymentRequest.routingInfo)
         case Nil =>
           sender ! SendPaymentToRouteResponse(paymentId, parentPaymentId, None)
           r.paymentRequest.paymentSecret match {
-            case Some(paymentSecret) => payFsm forward SendPaymentToRoute(r.route, Onion.createMultiPartPayload(r.amount, r.recipientAmount, finalExpiry, paymentSecret))
-            case None => payFsm forward SendPaymentToRoute(r.route, FinalLegacyPayload(r.recipientAmount, finalExpiry))
+            case Some(paymentSecret) => payFsm forward SendPaymentToRoute(r.route, Onion.createMultiPartPayload(r.amount, r.recipientAmount, finalExpiry, paymentSecret), r.paymentRequest.routingInfo)
+            case None => payFsm forward SendPaymentToRoute(r.route, FinalLegacyPayload(r.recipientAmount, finalExpiry), r.paymentRequest.routingInfo)
           }
         case _ =>
           sender ! PaymentFailed(paymentId, r.paymentHash, LocalFailure(TrampolineMultiNodeNotSupported) :: Nil)

eclair-core/src/main/scala/fr/acinq/eclair/payment/send/PaymentLifecycle.scala

@@ -72,7 +72,7 @@ class PaymentLifecycle(nodeParams: NodeParams, cfg: SendPaymentConfig, router: A
       span.tag("expiry", c.finalPayload.expiry.toLong)
       log.debug("sending {} to route {}", c.finalPayload.amount, c.hops.mkString("->"))
       val send = SendPayment(c.hops.last, c.finalPayload, maxAttempts = 1)
-      router ! FinalizeRoute(c.hops)
+      router ! FinalizeRoute(c.hops, c.assistedRoutes)
       if (cfg.storeInDb) {
         paymentsDb.addOutgoingPayment(OutgoingPayment(id, cfg.parentId, cfg.externalId, paymentHash, PaymentType.Standard, c.finalPayload.amount, cfg.recipientAmount, cfg.recipientNodeId, Platform.currentTime, cfg.paymentRequest, OutgoingPaymentStatus.Pending))
       }
@@ -282,7 +282,7 @@ object PaymentLifecycle {
    * @param hops         payment route to use.
    * @param finalPayload onion payload for the target node.
    */
-  case class SendPaymentToRoute(hops: Seq[PublicKey], finalPayload: FinalPayload) {
+  case class SendPaymentToRoute(hops: Seq[PublicKey], finalPayload: FinalPayload, assistedRoutes: Seq[Seq[ExtraHop]] = Nil) {
     require(hops.nonEmpty, s"payment route must not be empty")
     val targetNodeId = hops.last
   }

eclair-core/src/main/scala/fr/acinq/eclair/router/Router.scala

@@ -148,7 +148,7 @@ case class RouteRequest(source: PublicKey,
                         ignoreChannels: Set[ChannelDesc] = Set.empty,
                         routeParams: Option[RouteParams] = None)
 
-case class FinalizeRoute(hops: Seq[PublicKey])
+case class FinalizeRoute(hops: Seq[PublicKey], assistedRoutes: Seq[Seq[ExtraHop]] = Nil)
 
 case class RouteResponse(hops: Seq[ChannelHop], ignoreNodes: Set[PublicKey], ignoreChannels: Set[ChannelDesc], allowEmpty: Boolean = false) {
   require(allowEmpty || hops.nonEmpty, "route cannot be empty")
@@ -533,9 +533,13 @@ class Router(val nodeParams: NodeParams, watcher: ActorRef, initialized: Option[
       sender ! d
       stay
 
-    case Event(FinalizeRoute(partialHops), d) =>
+    case Event(FinalizeRoute(partialHops, assistedRoutes), d) =>
+      // NB: using a capacity of 0 msat will impact the path-finding algorithm. However here we don't run any path-finding, so it's ok.
+      val assistedChannels: Map[ShortChannelId, AssistedChannel] = assistedRoutes.flatMap(toAssistedChannels(_, partialHops.last, 0 msat)).toMap
+      val extraEdges = assistedChannels.values.map(ac => GraphEdge(ChannelDesc(ac.extraHop.shortChannelId, ac.extraHop.nodeId, ac.nextNodeId), toFakeUpdate(ac.extraHop, ac.htlcMaximum))).toSet
+      val g = extraEdges.foldLeft(d.graph) { case (g: DirectedGraph, e: GraphEdge) => g.addEdge(e) }
       // split into sublists [(a,b),(b,c), ...] then get the edges between each of those pairs
-      partialHops.sliding(2).map { case List(v1, v2) => d.graph.getEdgesBetween(v1, v2) }.toList match {
+      partialHops.sliding(2).map { case List(v1, v2) => g.getEdgesBetween(v1, v2) }.toList match {
         case edges if edges.nonEmpty && edges.forall(_.nonEmpty) =>
           val selectedEdges = edges.map(_.maxBy(_.update.htlcMaximumMsat.getOrElse(0 msat))) // select the largest edge
           val hops = selectedEdges.map(d => ChannelHop(d.desc.a, d.desc.b, d.update))
@@ -1299,11 +1303,12 @@ object Router {
 
   /**
    * Build a `reply_channel_range` message
-   * @param chunk chunk of scids
-   * @param chainHash chain hash
+   *
+   * @param chunk           chunk of scids
+   * @param chainHash       chain hash
    * @param defaultEncoding default encoding
-   * @param queryFlags_opt query flag set by the requester
-   * @param channels channels map
+   * @param queryFlags_opt  query flag set by the requester
+   * @param channels        channels map
    * @return a ReplyChannelRange object
    */
   def buildReplyChannelRange(chunk: ShortChannelIdsChunk, chainHash: ByteVector32, defaultEncoding: EncodingType, queryFlags_opt: Option[QueryChannelRangeTlv.QueryFlags], channels: SortedMap[ShortChannelId, PublicChannel]): ReplyChannelRange = {

eclair-core/src/test/scala/fr/acinq/eclair/payment/PaymentLifecycleSpec.scala

@@ -116,6 +116,29 @@ class PaymentLifecycleSpec extends BaseRouterSpec {
     assert(failureMessage == "Not all the nodes in the supplied route are connected with public channels")
   }
 
+  test("send to route (routing hints)") { routerFixture =>
+    val payFixture = createPaymentLifecycle()
+    import payFixture._
+
+    val recipient = randomKey.publicKey
+    val routingHint = Seq(Seq(ExtraHop(c, ShortChannelId(561), 1 msat, 100, CltvExpiryDelta(144))))
+    val request = SendPaymentToRoute(Seq(a, b, c, recipient), FinalLegacyPayload(defaultAmountMsat, defaultExpiry), routingHint)
+
+    sender.send(paymentFSM, request)
+    routerForwarder.expectMsg(FinalizeRoute(Seq(a, b, c, recipient), routingHint))
+    val Transition(_, WAITING_FOR_REQUEST, WAITING_FOR_ROUTE) = monitor.expectMsgClass(classOf[Transition[_]])
+
+    routerForwarder.forward(routerFixture.router)
+    val Transition(_, WAITING_FOR_ROUTE, WAITING_FOR_PAYMENT_COMPLETE) = monitor.expectMsgClass(classOf[Transition[_]])
+
+    // Payment accepted by the recipient.
+    sender.send(paymentFSM, UpdateFulfillHtlc(ByteVector32.Zeroes, 0, defaultPaymentHash))
+
+    val ps = sender.expectMsgType[PaymentSent]
+    assert(ps.id === parentId)
+    awaitCond(nodeParams.db.payments.getOutgoingPayment(id).exists(_.status.isInstanceOf[OutgoingPaymentStatus.Succeeded]))
+  }
+
   test("send with route prefix") { _ =>
     val payFixture = createPaymentLifecycle()
     import payFixture._