use 'r' field in invoice when making payments (routing hints)

electrum/lnbase.py

@@ -1018,19 +1018,18 @@ class Peer(PrintError):
         await self.receive_commitment(chan)
         self.revoke(chan)
 
-    async def pay(self, path, chan, amount_msat, payment_hash, pubkey_in_invoice, min_final_cltv_expiry):
+    async def pay(self, route: List[RouteEdge], chan, amount_msat, payment_hash, min_final_cltv_expiry):
         assert chan.get_state() == "OPEN", chan.get_state()
         assert amount_msat > 0, "amount_msat is not greater zero"
         height = self.network.get_local_height()
-        route = self.network.path_finder.create_route_from_path(path, self.lnworker.node_keypair.pubkey)
         hops_data = []
-        sum_of_deltas = sum(route_edge.channel_policy.cltv_expiry_delta for route_edge in route[1:])
+        sum_of_deltas = sum(route_edge.cltv_expiry_delta for route_edge in route[1:])
         total_fee = 0
         final_cltv_expiry_without_deltas = (height + min_final_cltv_expiry)
         final_cltv_expiry_with_deltas = final_cltv_expiry_without_deltas + sum_of_deltas
         for idx, route_edge in enumerate(route[1:]):
             hops_data += [OnionHopsDataSingle(OnionPerHop(route_edge.short_channel_id, amount_msat.to_bytes(8, "big"), final_cltv_expiry_without_deltas.to_bytes(4, "big")))]
-            total_fee += route_edge.channel_policy.fee_base_msat + ( amount_msat * route_edge.channel_policy.fee_proportional_millionths // 1000000 )
+            total_fee += route_edge.fee_base_msat + ( amount_msat * route_edge.fee_proportional_millionths // 1000000 )
         associated_data = payment_hash
         secret_key = os.urandom(32)
         hops_data += [OnionHopsDataSingle(OnionPerHop(b"\x00"*8, amount_msat.to_bytes(8, "big"), (final_cltv_expiry_without_deltas).to_bytes(4, "big")))]

electrum/lnrouter.py

@@ -28,7 +28,7 @@ import os
 import json
 import threading
 from collections import namedtuple, defaultdict
-from typing import Sequence, Union, Tuple, Optional
+from typing import Sequence, List, Tuple, Optional, Dict, NamedTuple
 import binascii
 import base64
 import asyncio
@@ -478,14 +478,13 @@ class ChannelDB(JsonDB):
                                    direction))
 
 
-class RouteEdge:
-
-    def __init__(self, node_id: bytes, short_channel_id: bytes,
-                 channel_policy: ChannelInfoDirectedPolicy):
-        # "if you travel through short_channel_id, you will reach node_id"
-        self.node_id = node_id
-        self.short_channel_id = short_channel_id
-        self.channel_policy = channel_policy
+class RouteEdge(NamedTuple("RouteEdge", [('node_id', bytes),
+                                         ('short_channel_id', bytes),
+                                         ('fee_base_msat', int),
+                                         ('fee_proportional_millionths', int),
+                                         ('cltv_expiry_delta', int)])):
+    """if you travel through short_channel_id, you will reach node_id"""
+    pass
 
 
 class LNPathFinder(PrintError):
@@ -578,7 +577,7 @@ class LNPathFinder(PrintError):
         path.reverse()
         return path
 
-    def create_route_from_path(self, path, from_node_id: bytes) -> Sequence[RouteEdge]:
+    def create_route_from_path(self, path, from_node_id: bytes) -> List[RouteEdge]:
         assert type(from_node_id) is bytes
         if path is None:
             raise Exception('cannot create route from None path')
@@ -591,6 +590,10 @@ class LNPathFinder(PrintError):
             channel_policy = channel_info.get_policy_for_node(prev_node_id)
             if channel_policy is None:
                 raise Exception('cannot find channel policy for short_channel_id: {}'.format(bh2u(short_channel_id)))
-            route.append(RouteEdge(node_id, short_channel_id, channel_policy))
+            route.append(RouteEdge(node_id,
+                                   short_channel_id,
+                                   channel_policy.fee_base_msat,
+                                   channel_policy.fee_proportional_millionths,
+                                   channel_policy.cltv_expiry_delta))
             prev_node_id = node_id
         return route

electrum/lnworker.py

@@ -27,6 +27,7 @@ from .lnutil import (Outpoint, calc_short_channel_id, LNPeerAddr,
 from .lnutil import LOCAL, REMOTE
 from .lnaddr import lndecode
 from .i18n import _
+from .lnrouter import RouteEdge
 
 
 NUM_PEERS_TARGET = 4
@@ -237,16 +238,12 @@ class LNWorker(PrintError):
     def pay(self, invoice, amount_sat=None):
         addr = lndecode(invoice, expected_hrp=constants.net.SEGWIT_HRP)
         payment_hash = addr.paymenthash
-        invoice_pubkey = addr.pubkey.serialize()
         amount_sat = (addr.amount * COIN) if addr.amount else amount_sat
         if amount_sat is None:
             raise InvoiceError(_("Missing amount"))
         amount_msat = int(amount_sat * 1000)
-        # TODO use 'r' field from invoice
-        path = self.network.path_finder.find_path_for_payment(self.node_keypair.pubkey, invoice_pubkey, amount_msat)
-        if path is None:
-            raise PaymentFailure(_("No path found"))
-        node_id, short_channel_id = path[0]
+        route = self._create_route_from_invoice(decoded_invoice=addr, amount_msat=amount_msat)
+        node_id, short_channel_id = route[0].node_id, route[0].short_channel_id
         peer = self.peers[node_id]
         with self.lock:
             channels = list(self.channels.values())
@@ -255,9 +252,37 @@ class LNWorker(PrintError):
                 break
         else:
             raise Exception("ChannelDB returned path with short_channel_id {} that is not in channel list".format(bh2u(short_channel_id)))
-        coro = peer.pay(path, chan, amount_msat, payment_hash, invoice_pubkey, addr.min_final_cltv_expiry)
+        coro = peer.pay(route, chan, amount_msat, payment_hash, addr.min_final_cltv_expiry)
         return addr, peer, asyncio.run_coroutine_threadsafe(coro, self.network.asyncio_loop)
 
+    def _create_route_from_invoice(self, decoded_invoice, amount_msat) -> List[RouteEdge]:
+        invoice_pubkey = decoded_invoice.pubkey.serialize()
+        # use 'r' field from invoice
+        route = None  # type: List[RouteEdge]
+        for tag_type, data in decoded_invoice.tags:
+            if tag_type != 'r': continue
+            private_route = data
+            if len(private_route) == 0: continue
+            border_node_pubkey = private_route[0][0]
+            path = self.network.path_finder.find_path_for_payment(self.node_keypair.pubkey, border_node_pubkey, amount_msat)
+            if path is None: continue
+            route = self.network.path_finder.create_route_from_path(path, self.node_keypair.pubkey)
+            # we need to shift the node pubkey by one towards the destination:
+            private_route_nodes = [edge[0] for edge in private_route][1:] + [invoice_pubkey]
+            private_route_rest = [edge[1:] for edge in private_route]
+            for node_pubkey, edge_rest in zip(private_route_nodes, private_route_rest):
+                short_channel_id, fee_base_msat, fee_proportional_millionths, cltv_expiry_delta = edge_rest
+                route.append(RouteEdge(node_pubkey, short_channel_id, fee_base_msat, fee_proportional_millionths,
+                                       cltv_expiry_delta))
+            break
+        # if could not find route using any hint; try without hint now
+        if route is None:
+            path = self.network.path_finder.find_path_for_payment(self.node_keypair.pubkey, invoice_pubkey, amount_msat)
+            if path is None:
+                raise PaymentFailure(_("No path found"))
+            route = self.network.path_finder.create_route_from_path(path, self.node_keypair.pubkey)
+        return route
+
     def add_invoice(self, amount_sat, message):
         payment_preimage = os.urandom(32)
         RHASH = sha256(payment_preimage)