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lnpeer: move htlc forwarding funcs to lnworker

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forwarding happens independent of the peer that received the htlc to
forward and fits better in lnworker.
This commit is contained in:
f321x
2025-09-17 14:09:03 +02:00
parent 3d27992fb7
commit d62b627a0b
3 changed files with 332 additions and 325 deletions
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324
electrum/lnpeer.py
View File

@@ -1926,57 +1926,6 @@ class Peer(Logger, EventListener):
self.send_message("commitment_signed", channel_id=chan.channel_id, signature=sig_64, num_htlcs=len(htlc_sigs), htlc_signature=b"".join(htlc_sigs)) self.send_message("commitment_signed", channel_id=chan.channel_id, signature=sig_64, num_htlcs=len(htlc_sigs), htlc_signature=b"".join(htlc_sigs))
return True return True
def create_onion_for_route(
self, *,
route: 'LNPaymentRoute',
amount_msat: int,
total_msat: int,
payment_hash: bytes,
min_final_cltv_delta: int,
payment_secret: bytes,
trampoline_onion: Optional[OnionPacket] = None,
):
# add features learned during "init" for direct neighbour:
route[0].node_features |= self.features
local_height = self.network.get_local_height()
final_cltv_abs = local_height + min_final_cltv_delta
hops_data, amount_msat, cltv_abs = calc_hops_data_for_payment(
route,
amount_msat,
final_cltv_abs=final_cltv_abs,
total_msat=total_msat,
payment_secret=payment_secret)
num_hops = len(hops_data)
self.logger.info(f"lnpeer.pay len(route)={len(route)}")
for i in range(len(route)):
self.logger.info(f" {i}: edge={route[i].short_channel_id} hop_data={hops_data[i]!r}")
assert final_cltv_abs <= cltv_abs, (final_cltv_abs, cltv_abs)
session_key = os.urandom(32) # session_key
# if we are forwarding a trampoline payment, add trampoline onion
if trampoline_onion:
self.logger.info(f'adding trampoline onion to final payload')
trampoline_payload = hops_data[-1].payload
trampoline_payload["trampoline_onion_packet"] = {
"version": trampoline_onion.version,
"public_key": trampoline_onion.public_key,
"hops_data": trampoline_onion.hops_data,
"hmac": trampoline_onion.hmac
}
if t_hops_data := trampoline_onion._debug_hops_data: # None if trampoline-forwarding
t_route = trampoline_onion._debug_route
assert t_route is not None
self.logger.info(f"lnpeer.pay len(t_route)={len(t_route)}")
for i in range(len(t_route)):
self.logger.info(f" {i}: t_node={t_route[i].end_node.hex()} hop_data={t_hops_data[i]!r}")
# create onion packet
payment_path_pubkeys = [x.node_id for x in route]
onion = new_onion_packet(payment_path_pubkeys, session_key, hops_data, associated_data=payment_hash) # must use another sessionkey
self.logger.info(f"starting payment. len(route)={len(hops_data)}.")
# create htlc
if cltv_abs > local_height + lnutil.NBLOCK_CLTV_DELTA_TOO_FAR_INTO_FUTURE:
raise PaymentFailure(f"htlc expiry too far into future. (in {cltv_abs-local_height} blocks)")
return onion, amount_msat, cltv_abs, session_key
def send_htlc( def send_htlc(
self, self,
*, *,
@@ -2019,7 +1968,7 @@ class Peer(Logger, EventListener):
assert len(route) > 0 assert len(route) > 0
if not chan.can_send_update_add_htlc(): if not chan.can_send_update_add_htlc():
raise PaymentFailure("Channel cannot send update_add_htlc") raise PaymentFailure("Channel cannot send update_add_htlc")
onion, amount_msat, cltv_abs, session_key = self.create_onion_for_route( onion, amount_msat, cltv_abs, session_key = self.lnworker.create_onion_for_route(
route=route, route=route,
amount_msat=amount_msat, amount_msat=amount_msat,
total_msat=total_msat, total_msat=total_msat,
@@ -2131,273 +2080,6 @@ class Peer(Logger, EventListener):
chan.receive_htlc(htlc, onion_packet) chan.receive_htlc(htlc, onion_packet)
util.trigger_callback('htlc_added', chan, htlc, RECEIVED) util.trigger_callback('htlc_added', chan, htlc, RECEIVED)
async def maybe_forward_htlc(
self, *,
incoming_chan: Channel,
htlc: UpdateAddHtlc,
processed_onion: ProcessedOnionPacket,
) -> str:
# Forward HTLC
# FIXME: there are critical safety checks MISSING here
# - for example; atm we forward first and then persist "forwarding_info",
# so if we segfault in-between and restart, we might forward an HTLC twice...
# (same for trampoline forwarding)
# - we could check for the exposure to dust HTLCs, see:
# https://github.com/ACINQ/eclair/pull/1985
def log_fail_reason(reason: str):
self.logger.debug(
f"maybe_forward_htlc. will FAIL HTLC: inc_chan={incoming_chan.get_id_for_log()}. "
f"{reason}. inc_htlc={str(htlc)}. onion_payload={processed_onion.hop_data.payload}")
forwarding_enabled = self.network.config.EXPERIMENTAL_LN_FORWARD_PAYMENTS
if not forwarding_enabled:
log_fail_reason("forwarding is disabled")
raise OnionRoutingFailure(code=OnionFailureCode.PERMANENT_CHANNEL_FAILURE, data=b'')
chain = self.network.blockchain()
if chain.is_tip_stale():
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')
try:
_next_chan_scid = processed_onion.hop_data.payload["short_channel_id"]["short_channel_id"] # type: bytes
next_chan_scid = ShortChannelID(_next_chan_scid)
except Exception:
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
try:
next_amount_msat_htlc = processed_onion.hop_data.payload["amt_to_forward"]["amt_to_forward"]
except Exception:
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
try:
next_cltv_abs = processed_onion.hop_data.payload["outgoing_cltv_value"]["outgoing_cltv_value"]
except Exception:
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
next_chan = self.lnworker.get_channel_by_short_id(next_chan_scid)
if self.lnworker.features.supports(LnFeatures.OPTION_ZEROCONF_OPT):
next_peer = self.lnworker.get_peer_by_static_jit_scid_alias(next_chan_scid)
else:
next_peer = None
if not next_chan and next_peer and next_peer.accepts_zeroconf():
# check if an already existing channel can be used.
# todo: split the payment
for next_chan in next_peer.channels.values():
if next_chan.can_pay(next_amount_msat_htlc):
break
else:
return await self.lnworker.open_channel_just_in_time(
next_peer=next_peer,
next_amount_msat_htlc=next_amount_msat_htlc,
next_cltv_abs=next_cltv_abs,
payment_hash=htlc.payment_hash,
next_onion=processed_onion.next_packet)
local_height = chain.height()
if next_chan is None:
log_fail_reason(f"cannot find next_chan {next_chan_scid}")
raise OnionRoutingFailure(code=OnionFailureCode.UNKNOWN_NEXT_PEER, data=b'')
outgoing_chan_upd = next_chan.get_outgoing_gossip_channel_update(scid=next_chan_scid)[2:]
outgoing_chan_upd_len = len(outgoing_chan_upd).to_bytes(2, byteorder="big")
outgoing_chan_upd_message = outgoing_chan_upd_len + outgoing_chan_upd
if not next_chan.can_send_update_add_htlc():
log_fail_reason(
f"next_chan {next_chan.get_id_for_log()} cannot send ctx updates. "
f"chan state {next_chan.get_state()!r}, peer state: {next_chan.peer_state!r}")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_CHANNEL_FAILURE, data=outgoing_chan_upd_message)
if not next_chan.can_pay(next_amount_msat_htlc):
log_fail_reason(f"transient error (likely due to insufficient funds): not next_chan.can_pay(amt)")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_CHANNEL_FAILURE, data=outgoing_chan_upd_message)
if htlc.cltv_abs - next_cltv_abs < next_chan.forwarding_cltv_delta:
log_fail_reason(
f"INCORRECT_CLTV_EXPIRY. "
f"{htlc.cltv_abs=} - {next_cltv_abs=} < {next_chan.forwarding_cltv_delta=}")
data = htlc.cltv_abs.to_bytes(4, byteorder="big") + outgoing_chan_upd_message
raise OnionRoutingFailure(code=OnionFailureCode.INCORRECT_CLTV_EXPIRY, data=data)
if htlc.cltv_abs - lnutil.MIN_FINAL_CLTV_DELTA_ACCEPTED <= local_height \
or next_cltv_abs <= local_height:
raise OnionRoutingFailure(code=OnionFailureCode.EXPIRY_TOO_SOON, data=outgoing_chan_upd_message)
if max(htlc.cltv_abs, next_cltv_abs) > local_height + lnutil.NBLOCK_CLTV_DELTA_TOO_FAR_INTO_FUTURE:
raise OnionRoutingFailure(code=OnionFailureCode.EXPIRY_TOO_FAR, data=b'')
forwarding_fees = fee_for_edge_msat(
forwarded_amount_msat=next_amount_msat_htlc,
fee_base_msat=next_chan.forwarding_fee_base_msat,
fee_proportional_millionths=next_chan.forwarding_fee_proportional_millionths)
if htlc.amount_msat - next_amount_msat_htlc < forwarding_fees:
data = next_amount_msat_htlc.to_bytes(8, byteorder="big") + outgoing_chan_upd_message
raise OnionRoutingFailure(code=OnionFailureCode.FEE_INSUFFICIENT, data=data)
if self._maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(htlc.payment_hash):
log_fail_reason(f"RHASH corresponds to payreq we created")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')
self.logger.info(
f"maybe_forward_htlc. will forward HTLC: inc_chan={incoming_chan.short_channel_id}. inc_htlc={str(htlc)}. "
f"next_chan={next_chan.get_id_for_log()}.")
next_peer = self.lnworker.peers.get(next_chan.node_id)
if next_peer is None:
log_fail_reason(f"next_peer offline ({next_chan.node_id.hex()})")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_CHANNEL_FAILURE, data=outgoing_chan_upd_message)
try:
next_htlc = next_peer.send_htlc(
chan=next_chan,
payment_hash=htlc.payment_hash,
amount_msat=next_amount_msat_htlc,
cltv_abs=next_cltv_abs,
onion=processed_onion.next_packet,
)
except BaseException as e:
log_fail_reason(f"error sending message to next_peer={next_chan.node_id.hex()}")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_CHANNEL_FAILURE, data=outgoing_chan_upd_message)
htlc_key = serialize_htlc_key(next_chan.get_scid_or_local_alias(), next_htlc.htlc_id)
return htlc_key
@log_exceptions
async def maybe_forward_trampoline(
self, *,
payment_hash: bytes,
inc_cltv_abs: int,
outer_onion: ProcessedOnionPacket,
trampoline_onion: ProcessedOnionPacket,
fw_payment_key: str,
) -> None:
forwarding_enabled = self.network.config.EXPERIMENTAL_LN_FORWARD_PAYMENTS
forwarding_trampoline_enabled = self.network.config.EXPERIMENTAL_LN_FORWARD_TRAMPOLINE_PAYMENTS
if not (forwarding_enabled and forwarding_trampoline_enabled):
self.logger.info(f"trampoline forwarding is disabled. failing htlc.")
raise OnionRoutingFailure(code=OnionFailureCode.PERMANENT_CHANNEL_FAILURE, data=b'')
payload = trampoline_onion.hop_data.payload
payment_data = payload.get('payment_data')
try:
payment_secret = payment_data['payment_secret'] if payment_data else os.urandom(32)
outgoing_node_id = payload["outgoing_node_id"]["outgoing_node_id"]
amt_to_forward = payload["amt_to_forward"]["amt_to_forward"]
out_cltv_abs = payload["outgoing_cltv_value"]["outgoing_cltv_value"]
if "invoice_features" in payload:
self.logger.info('forward_trampoline: legacy')
next_trampoline_onion = None
invoice_features = payload["invoice_features"]["invoice_features"]
invoice_routing_info = payload["invoice_routing_info"]["invoice_routing_info"]
r_tags = decode_routing_info(invoice_routing_info)
self.logger.info(f'r_tags {r_tags}')
# TODO legacy mpp payment, use total_msat from trampoline onion
else:
self.logger.info('forward_trampoline: end-to-end')
invoice_features = LnFeatures.BASIC_MPP_OPT
next_trampoline_onion = trampoline_onion.next_packet
r_tags = []
except Exception as e:
self.logger.exception('')
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
if self._maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(payment_hash):
self.logger.debug(
f"maybe_forward_trampoline. will FAIL HTLC(s). "
f"RHASH corresponds to payreq we created. {payment_hash.hex()=}")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')
# these are the fee/cltv paid by the sender
# pay_to_node will raise if they are not sufficient
total_msat = outer_onion.hop_data.payload["payment_data"]["total_msat"]
budget = PaymentFeeBudget(
fee_msat=total_msat - amt_to_forward,
cltv=inc_cltv_abs - out_cltv_abs,
)
self.logger.info(f'trampoline forwarding. budget={budget}')
self.logger.info(f'trampoline forwarding. {inc_cltv_abs=}, {out_cltv_abs=}')
# To convert abs vs rel cltvs, we need to guess blockheight used by original sender as "current blockheight".
# Blocks might have been mined since.
# - if we skew towards the past, we decrease our own cltv_budget accordingly (which is ok)
# - if we skew towards the future, we decrease the cltv_budget for the subsequent nodes in the path,
# which can result in them failing the payment.
# So we skew towards the past and guess that there has been 1 new block mined since the payment began:
local_height_of_onion_creator = self.network.get_local_height() - 1
cltv_budget_for_rest_of_route = out_cltv_abs - local_height_of_onion_creator
if budget.fee_msat < 1000:
raise OnionRoutingFailure(code=OnionFailureCode.TRAMPOLINE_FEE_INSUFFICIENT, data=b'')
if budget.cltv < 576:
raise OnionRoutingFailure(code=OnionFailureCode.TRAMPOLINE_EXPIRY_TOO_SOON, data=b'')
# do we have a connection to the node?
next_peer = self.lnworker.peers.get(outgoing_node_id)
if next_peer and next_peer.accepts_zeroconf():
self.logger.info(f'JIT: found next_peer')
for next_chan in next_peer.channels.values():
if next_chan.can_pay(amt_to_forward):
# todo: detect if we can do mpp
self.logger.info(f'jit: next_chan can pay')
break
else:
scid_alias = self.lnworker._scid_alias_of_node(next_peer.pubkey)
route = [RouteEdge(
start_node=next_peer.pubkey,
end_node=outgoing_node_id,
short_channel_id=scid_alias,
fee_base_msat=0,
fee_proportional_millionths=0,
cltv_delta=144,
node_features=0
)]
next_onion, amount_msat, cltv_abs, session_key = self.create_onion_for_route(
route=route,
amount_msat=amt_to_forward,
total_msat=amt_to_forward,
payment_hash=payment_hash,
min_final_cltv_delta=cltv_budget_for_rest_of_route,
payment_secret=payment_secret,
trampoline_onion=next_trampoline_onion,
)
await self.lnworker.open_channel_just_in_time(
next_peer=next_peer,
next_amount_msat_htlc=amt_to_forward,
next_cltv_abs=cltv_abs,
payment_hash=payment_hash,
next_onion=next_onion)
return
try:
await self.lnworker.pay_to_node(
node_pubkey=outgoing_node_id,
payment_hash=payment_hash,
payment_secret=payment_secret,
amount_to_pay=amt_to_forward,
min_final_cltv_delta=cltv_budget_for_rest_of_route,
r_tags=r_tags,
invoice_features=invoice_features,
fwd_trampoline_onion=next_trampoline_onion,
budget=budget,
attempts=100,
fw_payment_key=fw_payment_key,
)
except OnionRoutingFailure as e:
raise
except FeeBudgetExceeded:
raise OnionRoutingFailure(code=OnionFailureCode.TRAMPOLINE_FEE_INSUFFICIENT, data=b'')
except PaymentFailure as e:
self.logger.debug(
f"maybe_forward_trampoline. PaymentFailure for {payment_hash.hex()=}, {payment_secret.hex()=}: {e!r}")
raise OnionRoutingFailure(code=OnionFailureCode.UNKNOWN_NEXT_PEER, data=b'')
def _maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(self, payment_hash: bytes) -> bool:
"""Returns True if the HTLC should be failed.
We must not forward HTLCs with a matching payment_hash to a payment request we created.
Example attack:
- Bob creates payment request with HASH1, for 1 BTC; and gives the payreq to Alice
- Alice sends htlc A->B->C, for 1 sat, with HASH1
- Bob must not release the preimage of HASH1
"""
payment_info = self.lnworker.get_payment_info(payment_hash)
is_our_payreq = payment_info and payment_info.direction == RECEIVED
# note: If we don't have the preimage for a payment request, then it must be a hold invoice.
# Hold invoices are created by other parties (e.g. a counterparty initiating a submarine swap),
# and it is the other party choosing the payment_hash. If we failed HTLCs with payment_hashes colliding
# with hold invoices, then a party that can make us save a hold invoice for an arbitrary hash could
# also make us fail arbitrary HTLCs.
return bool(is_our_payreq and self.lnworker.get_preimage(payment_hash))
def check_accepted_htlc( def check_accepted_htlc(
self, *, self, *,
chan: Channel, chan: Channel,
@@ -2502,7 +2184,7 @@ class Peer(Logger, EventListener):
return None, None return None, None
# use the htlc key if we are forwarding # use the htlc key if we are forwarding
payment_key = serialize_htlc_key(chan.get_scid_or_local_alias(), htlc.htlc_id) payment_key = serialize_htlc_key(chan.get_scid_or_local_alias(), htlc.htlc_id)
callback = lambda: self.maybe_forward_htlc( callback = lambda: self.lnworker.maybe_forward_htlc(
incoming_chan=chan, incoming_chan=chan,
htlc=htlc, htlc=htlc,
processed_onion=processed_onion) processed_onion=processed_onion)
@@ -2572,7 +2254,7 @@ class Peer(Logger, EventListener):
already_forwarded=already_forwarded, already_forwarded=already_forwarded,
) )
else: else:
callback = lambda: self.maybe_forward_trampoline( callback = lambda: self.lnworker.maybe_forward_trampoline(
payment_hash=payment_hash, payment_hash=payment_hash,
inc_cltv_abs=htlc.cltv_abs, # TODO: use max or enforce same value across mpp parts inc_cltv_abs=htlc.cltv_abs, # TODO: use max or enforce same value across mpp parts
outer_onion=processed_onion, outer_onion=processed_onion,

329
electrum/lnworker.py
View File

@@ -32,7 +32,7 @@ from .i18n import _
from .json_db import stored_in from .json_db import stored_in
from .channel_db import UpdateStatus, ChannelDBNotLoaded, get_mychannel_info, get_mychannel_policy from .channel_db import UpdateStatus, ChannelDBNotLoaded, get_mychannel_info, get_mychannel_policy
from . import constants, util from . import constants, util, lnutil
from .util import ( from .util import (
profiler, OldTaskGroup, ESocksProxy, NetworkRetryManager, JsonRPCClient, NotEnoughFunds, EventListener, profiler, OldTaskGroup, ESocksProxy, NetworkRetryManager, JsonRPCClient, NotEnoughFunds, EventListener,
event_listener, bfh, InvoiceError, resolve_dns_srv, is_ip_address, log_exceptions, ignore_exceptions, event_listener, bfh, InvoiceError, resolve_dns_srv, is_ip_address, log_exceptions, ignore_exceptions,
@@ -71,17 +71,21 @@ from .lnutil import (
NBLOCK_CLTV_DELTA_TOO_FAR_INTO_FUTURE, GossipForwardingMessage, MIN_FUNDING_SAT, NBLOCK_CLTV_DELTA_TOO_FAR_INTO_FUTURE, GossipForwardingMessage, MIN_FUNDING_SAT,
RecvMPPResolution, ReceivedMPPStatus, RecvMPPResolution, ReceivedMPPStatus,
) )
from .lnonion import decode_onion_error, OnionFailureCode, OnionRoutingFailure, OnionPacket from .lnonion import (
decode_onion_error, OnionFailureCode, OnionRoutingFailure, OnionPacket,
ProcessedOnionPacket, calc_hops_data_for_payment, new_onion_packet,
)
from .lnmsg import decode_msg from .lnmsg import decode_msg
from .lnrouter import ( from .lnrouter import (
RouteEdge, LNPaymentRoute, LNPaymentPath, is_route_within_budget, NoChannelPolicy, LNPathInconsistent RouteEdge, LNPaymentRoute, LNPaymentPath, is_route_within_budget, NoChannelPolicy,
LNPathInconsistent, fee_for_edge_msat,
) )
from .lnwatcher import LNWatcher from .lnwatcher import LNWatcher
from .submarine_swaps import SwapManager from .submarine_swaps import SwapManager
from .mpp_split import suggest_splits, SplitConfigRating from .mpp_split import suggest_splits, SplitConfigRating
from .trampoline import ( from .trampoline import (
create_trampoline_route_and_onion, is_legacy_relay, trampolines_by_id, hardcoded_trampoline_nodes, create_trampoline_route_and_onion, is_legacy_relay, trampolines_by_id, hardcoded_trampoline_nodes,
is_hardcoded_trampoline is_hardcoded_trampoline, decode_routing_info
) )
if TYPE_CHECKING: if TYPE_CHECKING:
@@ -3349,6 +3353,323 @@ class LNWallet(LNWorker):
util.trigger_callback('channels_updated', self.wallet) util.trigger_callback('channels_updated', self.wallet)
self.lnwatcher.add_channel(cb) self.lnwatcher.add_channel(cb)
async def maybe_forward_htlc(
self, *,
incoming_chan: Channel,
htlc: UpdateAddHtlc,
processed_onion: ProcessedOnionPacket,
) -> str:
# Forward HTLC
# FIXME: there are critical safety checks MISSING here
# - for example; atm we forward first and then persist "forwarding_info",
# so if we segfault in-between and restart, we might forward an HTLC twice...
# (same for trampoline forwarding)
# - we could check for the exposure to dust HTLCs, see:
# https://github.com/ACINQ/eclair/pull/1985
def log_fail_reason(reason: str):
self.logger.debug(
f"_maybe_forward_htlc. will FAIL HTLC: inc_chan={incoming_chan.get_id_for_log()}. "
f"{reason}. inc_htlc={str(htlc)}. onion_payload={processed_onion.hop_data.payload}")
forwarding_enabled = self.network.config.EXPERIMENTAL_LN_FORWARD_PAYMENTS
if not forwarding_enabled:
log_fail_reason("forwarding is disabled")
raise OnionRoutingFailure(code=OnionFailureCode.PERMANENT_CHANNEL_FAILURE, data=b'')
chain = self.network.blockchain()
if chain.is_tip_stale():
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')
try:
_next_chan_scid = processed_onion.hop_data.payload["short_channel_id"]["short_channel_id"] # type: bytes
next_chan_scid = ShortChannelID(_next_chan_scid)
except Exception:
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
try:
next_amount_msat_htlc = processed_onion.hop_data.payload["amt_to_forward"]["amt_to_forward"]
except Exception:
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
try:
next_cltv_abs = processed_onion.hop_data.payload["outgoing_cltv_value"]["outgoing_cltv_value"]
except Exception:
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
next_chan = self.get_channel_by_short_id(next_chan_scid)
if self.features.supports(LnFeatures.OPTION_ZEROCONF_OPT):
next_peer = self.get_peer_by_static_jit_scid_alias(next_chan_scid)
else:
next_peer = None
if not next_chan and next_peer and next_peer.accepts_zeroconf():
# check if an already existing channel can be used.
# todo: split the payment
for next_chan in next_peer.channels.values():
if next_chan.can_pay(next_amount_msat_htlc):
break
else:
return await self.open_channel_just_in_time(
next_peer=next_peer,
next_amount_msat_htlc=next_amount_msat_htlc,
next_cltv_abs=next_cltv_abs,
payment_hash=htlc.payment_hash,
next_onion=processed_onion.next_packet)
local_height = chain.height()
if next_chan is None:
log_fail_reason(f"cannot find next_chan {next_chan_scid}")
raise OnionRoutingFailure(code=OnionFailureCode.UNKNOWN_NEXT_PEER, data=b'')
outgoing_chan_upd = next_chan.get_outgoing_gossip_channel_update(scid=next_chan_scid)[2:]
outgoing_chan_upd_len = len(outgoing_chan_upd).to_bytes(2, byteorder="big")
outgoing_chan_upd_message = outgoing_chan_upd_len + outgoing_chan_upd
if not next_chan.can_send_update_add_htlc():
log_fail_reason(
f"next_chan {next_chan.get_id_for_log()} cannot send ctx updates. "
f"chan state {next_chan.get_state()!r}, peer state: {next_chan.peer_state!r}")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_CHANNEL_FAILURE, data=outgoing_chan_upd_message)
if not next_chan.can_pay(next_amount_msat_htlc):
log_fail_reason(f"transient error (likely due to insufficient funds): not next_chan.can_pay(amt)")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_CHANNEL_FAILURE, data=outgoing_chan_upd_message)
if htlc.cltv_abs - next_cltv_abs < next_chan.forwarding_cltv_delta:
log_fail_reason(
f"INCORRECT_CLTV_EXPIRY. "
f"{htlc.cltv_abs=} - {next_cltv_abs=} < {next_chan.forwarding_cltv_delta=}")
data = htlc.cltv_abs.to_bytes(4, byteorder="big") + outgoing_chan_upd_message
raise OnionRoutingFailure(code=OnionFailureCode.INCORRECT_CLTV_EXPIRY, data=data)
if htlc.cltv_abs - lnutil.MIN_FINAL_CLTV_DELTA_ACCEPTED <= local_height \
or next_cltv_abs <= local_height:
raise OnionRoutingFailure(code=OnionFailureCode.EXPIRY_TOO_SOON, data=outgoing_chan_upd_message)
if max(htlc.cltv_abs, next_cltv_abs) > local_height + lnutil.NBLOCK_CLTV_DELTA_TOO_FAR_INTO_FUTURE:
raise OnionRoutingFailure(code=OnionFailureCode.EXPIRY_TOO_FAR, data=b'')
forwarding_fees = fee_for_edge_msat(
forwarded_amount_msat=next_amount_msat_htlc,
fee_base_msat=next_chan.forwarding_fee_base_msat,
fee_proportional_millionths=next_chan.forwarding_fee_proportional_millionths)
if htlc.amount_msat - next_amount_msat_htlc < forwarding_fees:
data = next_amount_msat_htlc.to_bytes(8, byteorder="big") + outgoing_chan_upd_message
raise OnionRoutingFailure(code=OnionFailureCode.FEE_INSUFFICIENT, data=data)
if self._maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(htlc.payment_hash):
log_fail_reason(f"RHASH corresponds to payreq we created")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')
self.logger.info(
f"maybe_forward_htlc. will forward HTLC: inc_chan={incoming_chan.short_channel_id}. inc_htlc={str(htlc)}. "
f"next_chan={next_chan.get_id_for_log()}.")
next_peer = self.peers.get(next_chan.node_id)
if next_peer is None:
log_fail_reason(f"next_peer offline ({next_chan.node_id.hex()})")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_CHANNEL_FAILURE, data=outgoing_chan_upd_message)
try:
next_htlc = next_peer.send_htlc(
chan=next_chan,
payment_hash=htlc.payment_hash,
amount_msat=next_amount_msat_htlc,
cltv_abs=next_cltv_abs,
onion=processed_onion.next_packet,
)
except BaseException as e:
log_fail_reason(f"error sending message to next_peer={next_chan.node_id.hex()}")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_CHANNEL_FAILURE, data=outgoing_chan_upd_message)
htlc_key = serialize_htlc_key(next_chan.get_scid_or_local_alias(), next_htlc.htlc_id)
return htlc_key
@log_exceptions
async def maybe_forward_trampoline(
self, *,
payment_hash: bytes,
inc_cltv_abs: int,
outer_onion: ProcessedOnionPacket,
trampoline_onion: ProcessedOnionPacket,
fw_payment_key: str,
) -> None:
forwarding_enabled = self.network.config.EXPERIMENTAL_LN_FORWARD_PAYMENTS
forwarding_trampoline_enabled = self.network.config.EXPERIMENTAL_LN_FORWARD_TRAMPOLINE_PAYMENTS
if not (forwarding_enabled and forwarding_trampoline_enabled):
self.logger.info(f"trampoline forwarding is disabled. failing htlc.")
raise OnionRoutingFailure(code=OnionFailureCode.PERMANENT_CHANNEL_FAILURE, data=b'')
payload = trampoline_onion.hop_data.payload
payment_data = payload.get('payment_data')
try:
payment_secret = payment_data['payment_secret'] if payment_data else os.urandom(32)
outgoing_node_id = payload["outgoing_node_id"]["outgoing_node_id"]
amt_to_forward = payload["amt_to_forward"]["amt_to_forward"]
out_cltv_abs = payload["outgoing_cltv_value"]["outgoing_cltv_value"]
if "invoice_features" in payload:
self.logger.info('forward_trampoline: legacy')
next_trampoline_onion = None
invoice_features = payload["invoice_features"]["invoice_features"]
invoice_routing_info = payload["invoice_routing_info"]["invoice_routing_info"]
r_tags = decode_routing_info(invoice_routing_info)
self.logger.info(f'r_tags {r_tags}')
# TODO legacy mpp payment, use total_msat from trampoline onion
else:
self.logger.info('forward_trampoline: end-to-end')
invoice_features = LnFeatures.BASIC_MPP_OPT
next_trampoline_onion = trampoline_onion.next_packet
r_tags = []
except Exception as e:
self.logger.exception('')
raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
if self._maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(payment_hash):
self.logger.debug(
f"maybe_forward_trampoline. will FAIL HTLC(s). "
f"RHASH corresponds to payreq we created. {payment_hash.hex()=}")
raise OnionRoutingFailure(code=OnionFailureCode.TEMPORARY_NODE_FAILURE, data=b'')
# these are the fee/cltv paid by the sender
# pay_to_node will raise if they are not sufficient
total_msat = outer_onion.hop_data.payload["payment_data"]["total_msat"]
budget = PaymentFeeBudget(
fee_msat=total_msat - amt_to_forward,
cltv=inc_cltv_abs - out_cltv_abs,
)
self.logger.info(f'trampoline forwarding. budget={budget}')
self.logger.info(f'trampoline forwarding. {inc_cltv_abs=}, {out_cltv_abs=}')
# To convert abs vs rel cltvs, we need to guess blockheight used by original sender as "current blockheight".
# Blocks might have been mined since.
# - if we skew towards the past, we decrease our own cltv_budget accordingly (which is ok)
# - if we skew towards the future, we decrease the cltv_budget for the subsequent nodes in the path,
# which can result in them failing the payment.
# So we skew towards the past and guess that there has been 1 new block mined since the payment began:
local_height_of_onion_creator = self.network.get_local_height() - 1
cltv_budget_for_rest_of_route = out_cltv_abs - local_height_of_onion_creator
if budget.fee_msat < 1000:
raise OnionRoutingFailure(code=OnionFailureCode.TRAMPOLINE_FEE_INSUFFICIENT, data=b'')
if budget.cltv < 576:
raise OnionRoutingFailure(code=OnionFailureCode.TRAMPOLINE_EXPIRY_TOO_SOON, data=b'')
# do we have a connection to the node?
next_peer = self.peers.get(outgoing_node_id)
if next_peer and next_peer.accepts_zeroconf():
self.logger.info(f'JIT: found next_peer')
for next_chan in next_peer.channels.values():
if next_chan.can_pay(amt_to_forward):
# todo: detect if we can do mpp
self.logger.info(f'jit: next_chan can pay')
break
else:
scid_alias = self._scid_alias_of_node(next_peer.pubkey)
route = [RouteEdge(
start_node=next_peer.pubkey,
end_node=outgoing_node_id,
short_channel_id=scid_alias,
fee_base_msat=0,
fee_proportional_millionths=0,
cltv_delta=144,
node_features=0
)]
next_onion, amount_msat, cltv_abs, session_key = self.create_onion_for_route(
route=route,
amount_msat=amt_to_forward,
total_msat=amt_to_forward,
payment_hash=payment_hash,
min_final_cltv_delta=cltv_budget_for_rest_of_route,
payment_secret=payment_secret,
trampoline_onion=next_trampoline_onion,
)
await self.open_channel_just_in_time(
next_peer=next_peer,
next_amount_msat_htlc=amt_to_forward,
next_cltv_abs=cltv_abs,
payment_hash=payment_hash,
next_onion=next_onion)
return
try:
await self.pay_to_node(
node_pubkey=outgoing_node_id,
payment_hash=payment_hash,
payment_secret=payment_secret,
amount_to_pay=amt_to_forward,
min_final_cltv_delta=cltv_budget_for_rest_of_route,
r_tags=r_tags,
invoice_features=invoice_features,
fwd_trampoline_onion=next_trampoline_onion,
budget=budget,
attempts=100,
fw_payment_key=fw_payment_key,
)
except OnionRoutingFailure as e:
raise
except FeeBudgetExceeded:
raise OnionRoutingFailure(code=OnionFailureCode.TRAMPOLINE_FEE_INSUFFICIENT, data=b'')
except PaymentFailure as e:
self.logger.debug(
f"maybe_forward_trampoline. PaymentFailure for {payment_hash.hex()=}, {payment_secret.hex()=}: {e!r}")
raise OnionRoutingFailure(code=OnionFailureCode.UNKNOWN_NEXT_PEER, data=b'')
def _maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created(self, payment_hash: bytes) -> bool:
"""Returns True if the HTLC should be failed.
We must not forward HTLCs with a matching payment_hash to a payment request we created.
Example attack:
- Bob creates payment request with HASH1, for 1 BTC; and gives the payreq to Alice
- Alice sends htlc A->B->C, for 1 sat, with HASH1
- Bob must not release the preimage of HASH1
"""
payment_info = self.get_payment_info(payment_hash)
is_our_payreq = payment_info and payment_info.direction == RECEIVED
# note: If we don't have the preimage for a payment request, then it must be a hold invoice.
# Hold invoices are created by other parties (e.g. a counterparty initiating a submarine swap),
# and it is the other party choosing the payment_hash. If we failed HTLCs with payment_hashes colliding
# with hold invoices, then a party that can make us save a hold invoice for an arbitrary hash could
# also make us fail arbitrary HTLCs.
return bool(is_our_payreq and self.get_preimage(payment_hash))
def create_onion_for_route(
self, *,
route: 'LNPaymentRoute',
amount_msat: int,
total_msat: int,
payment_hash: bytes,
min_final_cltv_delta: int,
payment_secret: bytes,
trampoline_onion: Optional[OnionPacket] = None,
):
# add features learned during "init" for direct neighbour:
route[0].node_features |= self.features
local_height = self.network.get_local_height()
final_cltv_abs = local_height + min_final_cltv_delta
hops_data, amount_msat, cltv_abs = calc_hops_data_for_payment(
route,
amount_msat,
final_cltv_abs=final_cltv_abs,
total_msat=total_msat,
payment_secret=payment_secret)
num_hops = len(hops_data)
self.logger.info(f"pay len(route)={len(route)}")
for i in range(len(route)):
self.logger.info(f" {i}: edge={route[i].short_channel_id} hop_data={hops_data[i]!r}")
assert final_cltv_abs <= cltv_abs, (final_cltv_abs, cltv_abs)
session_key = os.urandom(32) # session_key
# if we are forwarding a trampoline payment, add trampoline onion
if trampoline_onion:
self.logger.info(f'adding trampoline onion to final payload')
trampoline_payload = hops_data[-1].payload
trampoline_payload["trampoline_onion_packet"] = {
"version": trampoline_onion.version,
"public_key": trampoline_onion.public_key,
"hops_data": trampoline_onion.hops_data,
"hmac": trampoline_onion.hmac
}
if t_hops_data := trampoline_onion._debug_hops_data: # None if trampoline-forwarding
t_route = trampoline_onion._debug_route
assert t_route is not None
self.logger.info(f"lnpeer.pay len(t_route)={len(t_route)}")
for i in range(len(t_route)):
self.logger.info(f" {i}: t_node={t_route[i].end_node.hex()} hop_data={t_hops_data[i]!r}")
# create onion packet
payment_path_pubkeys = [x.node_id for x in route]
onion = new_onion_packet(payment_path_pubkeys, session_key, hops_data, associated_data=payment_hash) # must use another sessionkey
self.logger.info(f"starting payment. len(route)={len(hops_data)}.")
# create htlc
if cltv_abs > local_height + lnutil.NBLOCK_CLTV_DELTA_TOO_FAR_INTO_FUTURE:
raise PaymentFailure(f"htlc expiry too far into future. (in {cltv_abs-local_height} blocks)")
return onion, amount_msat, cltv_abs, session_key
def save_forwarding_failure( def save_forwarding_failure(
self, self,
payment_key: str, payment_key: str,

4
tests/test_lnpeer.py
View File

@@ -347,6 +347,10 @@ class MockLNWallet(Logger, EventListener, NetworkRetryManager[LNPeerAddr]):
current_target_feerate_per_kw = LNWallet.current_target_feerate_per_kw current_target_feerate_per_kw = LNWallet.current_target_feerate_per_kw
current_low_feerate_per_kw_srk_channel = LNWallet.current_low_feerate_per_kw_srk_channel current_low_feerate_per_kw_srk_channel = LNWallet.current_low_feerate_per_kw_srk_channel
maybe_cleanup_mpp = LNWallet.maybe_cleanup_mpp maybe_cleanup_mpp = LNWallet.maybe_cleanup_mpp
create_onion_for_route = LNWallet.create_onion_for_route
maybe_forward_htlc = LNWallet.maybe_forward_htlc
maybe_forward_trampoline = LNWallet.maybe_forward_trampoline
_maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created = LNWallet._maybe_refuse_to_forward_htlc_that_corresponds_to_payreq_we_created
class MockTransport: class MockTransport: