trampoline MPP: fix total_msat in trampoline onion, and bucketing

electrum/lnworker.py

@@ -1145,7 +1145,10 @@ class LNWallet(LNWorker):
 
         key = (payment_hash, short_channel_id, htlc.htlc_id)
         self.sent_htlcs_routes[key] = route, payment_secret, amount_msat, total_msat
-        self.sent_buckets[payment_secret] = total_msat
+        # if we sent MPP to a trampoline, add item to sent_buckets
+        if not self.channel_db and amount_msat != total_msat:
+            if payment_secret not in self.sent_buckets:
+                self.sent_buckets[payment_secret] = total_msat
         util.trigger_callback('htlc_added', chan, htlc, SENT)
 
     def handle_error_code_from_failed_htlc(self, htlc_log):
@@ -1299,7 +1302,6 @@ class LNWallet(LNWorker):
             payment_hash,
             payment_secret,
             full_path: LNPaymentPath = None) -> Sequence[Tuple[LNPaymentRoute, int]]:
-        # FIXME trampoline case broken if amount_msat != final_total_msat
 
         """Creates multiple routes for splitting a payment over the available
         private channels.
@@ -1323,7 +1325,7 @@ class LNWallet(LNWorker):
                         continue
                     trampoline_onion, trampoline_fee, amount_with_fees, cltv_delta = create_trampoline_route_and_onion(
                         amount_msat=amount_msat,
-                        bucket_amount_msat=amount_msat,
+                        total_msat=final_total_msat,
                         min_cltv_expiry=min_cltv_expiry,
                         my_pubkey=self.node_keypair.pubkey,
                         invoice_pubkey=invoice_pubkey,
@@ -1387,8 +1389,8 @@ class LNWallet(LNWorker):
                         for node_id, bucket in buckets.items():
                             bucket_amount_msat = sum([x[1] for x in bucket])
                             trampoline_onion, trampoline_fee, bucket_amount_with_fees, bucket_cltv_delta = create_trampoline_route_and_onion(
-                                amount_msat=amount_msat,
-                                bucket_amount_msat=bucket_amount_msat,
+                                amount_msat=bucket_amount_msat,
+                                total_msat=final_total_msat,
                                 min_cltv_expiry=min_cltv_expiry,
                                 my_pubkey=self.node_keypair.pubkey,
                                 invoice_pubkey=invoice_pubkey,
@@ -1707,13 +1709,14 @@ class LNWallet(LNWorker):
                 sender_idx = None
             self.logger.info(f"htlc_failed {failure_message}")
 
-            # FIXME: maybe only check this bucketing stuff if not using trampoline?
-            # if payment_secret in self.sent_buckets:
-            #     self.sent_buckets[payment_secret] -= amount_msat
-            #     if self.sent_buckets[payment_secret] > 0:
-            #         return
-            #     else:
-            #         amount_msat = bucket_msat
+            # check sent_buckets if we use trampoline
+            if self.channel_db is None and payment_secret in self.sent_buckets:
+                self.sent_buckets[payment_secret] -= amount_msat
+                if self.sent_buckets[payment_secret] > 0:
+                    return
+                else:
+                    amount_msat = bucket_msat
+
             htlc_log = HtlcLog(
                 success=False,
                 route=route,

electrum/trampoline.py

@@ -63,7 +63,6 @@ def encode_routing_info(r_tags):
 def create_trampoline_route(
         *,
         amount_msat:int,
-        bucket_amount_msat:int,
         min_cltv_expiry:int,
         invoice_pubkey:bytes,
         invoice_features:int,
@@ -161,7 +160,7 @@ def create_trampoline_route(
     return route
 
 
-def create_trampoline_onion(route, amount_msat, final_cltv, total_msat, payment_hash, payment_secret):
+def create_trampoline_onion(*, route, amount_msat, final_cltv, total_msat, payment_hash, payment_secret):
     # all edges are trampoline
     hops_data, amount_msat, cltv = calc_hops_data_for_payment(
         route,
@@ -196,7 +195,7 @@ def create_trampoline_onion(route, amount_msat, final_cltv, total_msat, payment_
 def create_trampoline_route_and_onion(
         *,
         amount_msat,
-        bucket_amount_msat,
+        total_msat,
         min_cltv_expiry,
         invoice_pubkey,
         invoice_features,
@@ -211,7 +210,6 @@ def create_trampoline_route_and_onion(
     # create route for the trampoline_onion
     trampoline_route = create_trampoline_route(
         amount_msat=amount_msat,
-        bucket_amount_msat=bucket_amount_msat,
         min_cltv_expiry=min_cltv_expiry,
         my_pubkey=my_pubkey,
         invoice_pubkey=invoice_pubkey,
@@ -223,15 +221,15 @@ def create_trampoline_route_and_onion(
         trampoline2_list=trampoline2_list)
     # compute onion and fees
     final_cltv = local_height + min_cltv_expiry
-    trampoline_onion, bucket_amount_with_fees, bucket_cltv = create_trampoline_onion(
-        trampoline_route,
-        bucket_amount_msat,
-        final_cltv,
-        amount_msat,
-        payment_hash,
-        payment_secret)
+    trampoline_onion, amount_with_fees, bucket_cltv = create_trampoline_onion(
+        route=trampoline_route,
+        amount_msat=amount_msat,
+        final_cltv=final_cltv,
+        total_msat=total_msat,
+        payment_hash=payment_hash,
+        payment_secret=payment_secret)
     bucket_cltv_delta = bucket_cltv - local_height
     bucket_cltv_delta += trampoline_route[0].cltv_expiry_delta
     # trampoline fee for this very trampoline
-    trampoline_fee = trampoline_route[0].fee_for_edge(bucket_amount_with_fees)
-    return trampoline_onion, trampoline_fee, bucket_amount_with_fees, bucket_cltv_delta
+    trampoline_fee = trampoline_route[0].fee_for_edge(amount_with_fees)
+    return trampoline_onion, trampoline_fee, amount_with_fees, bucket_cltv_delta