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lnworker: add sanity check to trampoline forwarding #10902

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lnworker: add sanity check to trampoline forwarding #10902

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8 changes: 6 additions & 2 deletions electrum/lnworker.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3954,10 +3954,13 @@ async def maybe_forward_htlc_set(
min_inc_cltv_abs = min(
mpp_htlc.htlc.cltv_abs
for mpp_htlc in processed_htlc_set.keys()) # take "min" to assume worst-case
total_msat = any_outer_onion.total_msat
sum_inc_amt_msat = sum(mpp_htlc.htlc.amount_msat for mpp_htlc in processed_htlc_set)
assert total_msat <= sum_inc_amt_msat, f"{total_msat=} should be <= {sum_inc_amt_msat=}"
await self._maybe_forward_trampoline(
payment_hash=any_mpp_htlc.htlc.payment_hash,
closest_inc_cltv_abs=min_inc_cltv_abs,
total_msat=any_outer_onion.total_msat,
total_msat=total_msat,
any_trampoline_onion=any_trampoline_onion,
fw_payment_key=payment_key,
)
Expand Down Expand Up @@ -4094,7 +4097,7 @@ async def _maybe_forward_trampoline(
self, *,
payment_hash: bytes,
closest_inc_cltv_abs: int,
total_msat: int, # total_msat of the outer onion
total_msat: int, # total_msat of the outer onion. this is <= sum_inc_amt_msat
any_trampoline_onion: ProcessedOnionPacket, # any trampoline onion of the incoming htlc set, they should be similar
fw_payment_key: str,
) -> None:
Expand Down Expand Up @@ -4134,6 +4137,7 @@ async def _maybe_forward_trampoline(
f"RHASH corresponds to payreq we created. {payment_hash.hex()=}")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')

assert total_msat >= amt_to_forward # sanity check: money_in >= money_out

@ecdsa ecdsa Aug 31, 2026

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maybe add closest_inc_cltv_abs >= out_cltv_abs ?

# these are the fee/cltv paid by the sender
# pay_to_node will raise if they are not sufficient
budget = PaymentFeeBudget(
Expand Down
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