Trampoline MPP aggregation:
- trampoline node is the final recipient of MPP - each trampoline receives a bucket of HTLCs - if a HTLC from a bucket fails, wait for the entire bucket to fail - move trampoline route and onion code into trampoline module
This commit is contained in:
ThomasV
228
electrum/trampoline.py
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228
electrum/trampoline.py
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import os
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import bitstring
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from .lnutil import LnFeatures
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from .lnonion import calc_hops_data_for_payment, new_onion_packet
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from .lnrouter import RouteEdge, TrampolineEdge, LNPaymentRoute, is_route_sane_to_use
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from .lnutil import NoPathFound
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from .logging import get_logger, Logger
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_logger = get_logger(__name__)
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# trampoline nodes are supposed to advertise their fee and cltv in node_update message
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TRAMPOLINE_FEES = [
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{
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'fee_base_msat': 0,
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'fee_proportional_millionths': 0,
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'cltv_expiry_delta': 576,
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},
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{
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'fee_base_msat': 1000,
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'fee_proportional_millionths': 100,
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'cltv_expiry_delta': 576,
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},
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{
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'fee_base_msat': 3000,
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'fee_proportional_millionths': 100,
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'cltv_expiry_delta': 576,
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},
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{
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'fee_base_msat': 5000,
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'fee_proportional_millionths': 500,
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'cltv_expiry_delta': 576,
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},
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{
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'fee_base_msat': 7000,
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'fee_proportional_millionths': 1000,
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'cltv_expiry_delta': 576,
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},
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{
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'fee_base_msat': 12000,
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'fee_proportional_millionths': 3000,
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'cltv_expiry_delta': 576,
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},
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{
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'fee_base_msat': 100000,
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'fee_proportional_millionths': 3000,
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'cltv_expiry_delta': 576,
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},
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]
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def encode_routing_info(r_tags):
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result = bitstring.BitArray()
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for route in r_tags:
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result.append(bitstring.pack('uint:8', len(route)))
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for step in route:
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pubkey, channel, feebase, feerate, cltv = step
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result.append(bitstring.BitArray(pubkey) + bitstring.BitArray(channel) + bitstring.pack('intbe:32', feebase) + bitstring.pack('intbe:32', feerate) + bitstring.pack('intbe:16', cltv))
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return result.tobytes()
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def create_trampoline_route(
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amount_msat:int,
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bucket_amount_msat:int,
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min_cltv_expiry:int,
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invoice_pubkey:bytes,
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invoice_features:int,
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trampoline_node_id,
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r_tags, t_tags,
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trampoline_fee_level,
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trampoline2_list) -> LNPaymentRoute:
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invoice_features = LnFeatures(invoice_features)
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# We do not set trampoline_routing_opt in our invoices, because the spec is not ready
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# Do not use t_tags if the flag is set, because we the format is not decided yet
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if invoice_features.supports(LnFeatures.OPTION_TRAMPOLINE_ROUTING_OPT):
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is_legacy = False
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if len(r_tags) > 0 and len(r_tags[0]) == 1:
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pubkey, scid, feebase, feerate, cltv = r_tags[0][0]
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t_tag = pubkey, feebase, feerate, cltv
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else:
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t_tag = None
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elif len(t_tags) > 0:
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is_legacy = False
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t_tag = t_tags[0]
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else:
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is_legacy = True
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# fee level. the same fee is used for all trampolines
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if trampoline_fee_level < len(TRAMPOLINE_FEES):
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params = TRAMPOLINE_FEES[trampoline_fee_level]
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else:
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raise NoPathFound()
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# add optional second trampoline
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trampoline2 = None
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if is_legacy:
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for node_id in trampoline2_list:
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if node_id != trampoline_node_id:
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trampoline2 = node_id
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break
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# node_features is only used to determine is_tlv
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trampoline_features = LnFeatures.VAR_ONION_OPT
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# hop to trampoline
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route = []
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# trampoline hop
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route.append(
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TrampolineEdge(
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node_id=trampoline_node_id,
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fee_base_msat=params['fee_base_msat'],
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fee_proportional_millionths=params['fee_proportional_millionths'],
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cltv_expiry_delta=params['cltv_expiry_delta'],
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node_features=trampoline_features))
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if trampoline2:
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route.append(
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TrampolineEdge(
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node_id=trampoline2,
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fee_base_msat=params['fee_base_msat'],
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fee_proportional_millionths=params['fee_proportional_millionths'],
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cltv_expiry_delta=params['cltv_expiry_delta'],
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node_features=trampoline_features))
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# add routing info
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if is_legacy:
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invoice_routing_info = encode_routing_info(r_tags)
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route[-1].invoice_routing_info = invoice_routing_info
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route[-1].invoice_features = invoice_features
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else:
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if t_tag:
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pubkey, feebase, feerate, cltv = t_tag
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if route[-1].node_id != pubkey:
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route.append(
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TrampolineEdge(
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node_id=pubkey,
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fee_base_msat=feebase,
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fee_proportional_millionths=feerate,
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cltv_expiry_delta=cltv,
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node_features=trampoline_features))
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# Fake edge (not part of actual route, needed by calc_hops_data)
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route.append(
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TrampolineEdge(
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node_id=invoice_pubkey,
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fee_base_msat=0,
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fee_proportional_millionths=0,
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cltv_expiry_delta=0,
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node_features=trampoline_features))
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# check that we can pay amount and fees
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for edge in route[::-1]:
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amount_msat += edge.fee_for_edge(amount_msat)
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if not is_route_sane_to_use(route, amount_msat, min_cltv_expiry):
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raise NoPathFound()
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_logger.info(f'created route with trampoline: fee_level={trampoline_fee_level}, is legacy: {is_legacy}')
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_logger.info(f'first trampoline: {trampoline_node_id.hex()}')
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_logger.info(f'second trampoline: {trampoline2.hex() if trampoline2 else None}')
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_logger.info(f'params: {params}')
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return route
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def create_trampoline_onion(route, amount_msat, final_cltv, total_msat, payment_hash, payment_secret):
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# all edges are trampoline
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hops_data, amount_msat, cltv = calc_hops_data_for_payment(
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route,
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amount_msat,
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final_cltv,
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total_msat=total_msat,
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payment_secret=payment_secret)
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# detect trampoline hops.
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payment_path_pubkeys = [x.node_id for x in route]
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num_hops = len(payment_path_pubkeys)
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for i in range(num_hops-1):
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route_edge = route[i]
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next_edge = route[i+1]
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assert route_edge.is_trampoline()
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assert next_edge.is_trampoline()
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hops_data[i].payload["outgoing_node_id"] = {"outgoing_node_id":next_edge.node_id}
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if route_edge.invoice_features:
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hops_data[i].payload["invoice_features"] = {"invoice_features":route_edge.invoice_features}
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if route_edge.invoice_routing_info:
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hops_data[i].payload["invoice_routing_info"] = {"invoice_routing_info":route_edge.invoice_routing_info}
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# only for final, legacy
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if i == num_hops - 2:
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hops_data[i].payload["payment_data"] = {
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"payment_secret":payment_secret,
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"total_msat": total_msat,
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}
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trampoline_session_key = os.urandom(32)
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trampoline_onion = new_onion_packet(payment_path_pubkeys, trampoline_session_key, hops_data, associated_data=payment_hash, trampoline=True)
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return trampoline_onion, amount_msat, cltv
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def create_trampoline_route_and_onion(
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*,
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amount_msat,
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bucket_amount_msat,
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min_cltv_expiry,
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invoice_pubkey,
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invoice_features,
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node_id,
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r_tags, t_tags,
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payment_hash,
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payment_secret,
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local_height:int,
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trampoline_fee_level,
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trampoline2_list):
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# create route for the trampoline_onion
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trampoline_route = create_trampoline_route(
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amount_msat,
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bucket_amount_msat,
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min_cltv_expiry,
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invoice_pubkey,
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invoice_features,
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node_id,
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r_tags, t_tags,
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trampoline_fee_level,
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trampoline2_list)
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# compute onion and fees
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final_cltv = local_height + min_cltv_expiry
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trampoline_onion, bucket_amount_with_fees, bucket_cltv = create_trampoline_onion(
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trampoline_route,
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bucket_amount_msat,
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final_cltv,
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amount_msat,
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payment_hash,
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payment_secret)
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bucket_cltv_delta = bucket_cltv - local_height
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bucket_cltv_delta += trampoline_route[0].cltv_expiry_delta
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# trampoline fee for this very trampoline
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trampoline_fee = trampoline_route[0].fee_for_edge(bucket_amount_with_fees)
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return trampoline_onion, trampoline_fee, bucket_amount_with_fees, bucket_cltv_delta
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