rebalance.py: Fixing setup_routing_fees() and peer_from_scid() for unannounced channels (#670)

* -Fixing setup_routing_fees() and peer_from_scid() to properly handle
unannounced channels, as the listchannels command does not lists them.

* -Removing unnecessary condition

* rebalance.py: Aliases were not used for route_in and route_out. Some
peers that do support aliases generated an error when trying to send the
rebalancing payment.

Author: 21M4TW

rebalance/rebalance.py

@@ -44,18 +44,38 @@ def route_get_msat(r):
 
 def setup_routing_fees(route, msat):
     delay = plugin.cltv_final
-    for r in reversed(route):
+    if plugin.listpeerchannels:
+        loop_first_channel = -2
+        r = route[-1]
+        route_set_msat(r, msat)
+        r["delay"] = delay
+        channels = plugin.rpc.listpeerchannels(route[-2]["id"]).get("channels")
+        ch = next(c["updates"]["remote"] for c in channels if c["short_channel_id"] == r["channel"] or c["alias"].get("remote") == r["channel"])
+        fee = Millisatoshi(ch["fee_base_msat"])
+        # BOLT #7 requires fee >= fee_base_msat + ( amount_to_forward * fee_proportional_millionths / 1000000 )
+        fee += (
+            msat * ch["fee_proportional_millionths"] + 10**6 - 1
+        ) // 10**6  # integer math trick to round up
+        msat += fee
+        delay += ch["cltv_expiry_delta"]
+    else:
+        loop_first_channel = -1
+
+    for r in route[loop_first_channel:0:-1]:
         route_set_msat(r, msat)
         r["delay"] = delay
-        channels = plugin.rpc.listchannels(r["channel"])
-        ch = next(c for c in channels.get("channels") if c["destination"] == r["id"])
+        channels = plugin.rpc.listchannels(r["channel"]).get("channels")
+        ch = next(c for c in channels if c["destination"] == r["id"])
         fee = Millisatoshi(ch["base_fee_millisatoshi"])
         # BOLT #7 requires fee >= fee_base_msat + ( amount_to_forward * fee_proportional_millionths / 1000000 )
         fee += (
             msat * ch["fee_per_millionth"] + 10**6 - 1
         ) // 10**6  # integer math trick to round up
         msat += fee
         delay += ch["delay"]
+    r = route[0]
+    route_set_msat(r, msat)
+    r["delay"] = delay
 
 
 def get_channel(payload, peer_id, scid, check_state: bool = False):
@@ -109,10 +129,16 @@ def amounts_from_scid(scid):
 
 
 def peer_from_scid(short_channel_id, my_node_id, payload):
-    channels = plugin.rpc.listchannels(short_channel_id).get("channels")
-    for ch in channels:
-        if ch["source"] == my_node_id:
-            return ch["destination"]
+    if plugin.listpeerchannels:
+        channels = plugin.rpc.listpeerchannels().get("channels")
+        for ch in channels:
+            if ch["short_channel_id"] == short_channel_id:
+                return ch["peer_id"]
+    else:
+        channels = plugin.rpc.listchannels(short_channel_id).get("channels")
+        for ch in channels:
+            if ch["source"] == my_node_id:
+                return ch["destination"]
     raise RpcError(
         "rebalance",
         payload,
@@ -329,8 +355,10 @@ def rebalance(
     my_node_id = plugin.getinfo.get("id")
     outgoing_node_id = peer_from_scid(outgoing_scid, my_node_id, payload)
     incoming_node_id = peer_from_scid(incoming_scid, my_node_id, payload)
-    get_channel(payload, outgoing_node_id, outgoing_scid, True)
-    get_channel(payload, incoming_node_id, incoming_scid, True)
+    out_aliases = get_channel(payload, outgoing_node_id, outgoing_scid, True).get("alias")
+    out_alias = out_aliases.get("local") if (out_aliases and out_aliases.get("local")) else outgoing_scid
+    in_aliases = get_channel(payload, incoming_node_id, incoming_scid, True).get("alias")
+    in_alias = in_aliases.get("remote") if (in_aliases and in_aliases.get("remote")) else incoming_scid
     out_ours, out_total = amounts_from_scid(outgoing_scid)
     in_ours, in_total = amounts_from_scid(incoming_scid)
 
@@ -350,12 +378,12 @@ def rebalance(
 
     route_out = {
         "id": outgoing_node_id,
-        "channel": outgoing_scid,
+        "channel": out_alias,
         "direction": int(not my_node_id < outgoing_node_id),
     }
     route_in = {
         "id": my_node_id,
-        "channel": incoming_scid,
+        "channel": in_alias,
         "direction": int(not incoming_node_id < my_node_id),
     }
     start_ts = int(time.time())