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onion_message: factor out get_blinded_paths_to_me from get_blinded_reply_paths.

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the former also calculates payinfo information for payment scenarios.
include payment_relay struct for payment blinded_paths.
This commit is contained in:
Sander van Grieken
2025-10-08 15:34:16 +02:00
committed by f321x
parent 65fb739584
commit b7a512845f
1 changed files with 107 additions and 23 deletions
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electrum/onion_message.py
+107 -23
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@@ -31,10 +31,11 @@ import dataclasses
from random import random
from types import MappingProxyType
from typing import TYPE_CHECKING, Optional, Sequence, NamedTuple, List
from typing import TYPE_CHECKING, Optional, Sequence, NamedTuple, Tuple
import electrum_ecc as ecc
from electrum.channel_db import get_mychannel_policy
from electrum.lnrouter import PathEdge
from electrum.logging import get_logger, Logger
from electrum.crypto import sha256, get_ecdh
@@ -42,7 +43,7 @@ from electrum.lnmsg import OnionWireSerializer
from electrum.lnonion import (get_bolt04_onion_key, OnionPacket, process_onion_packet,
OnionHopsDataSingle, decrypt_onionmsg_data_tlv, encrypt_onionmsg_data_tlv,
get_shared_secrets_along_route, new_onion_packet, encrypt_hops_recipient_data)
from electrum.lnutil import LnFeatures
from electrum.lnutil import LnFeatures, MIN_FINAL_CLTV_DELTA_ACCEPTED, MAXIMUM_REMOTE_TO_SELF_DELAY_ACCEPTED
from electrum.util import OldTaskGroup, log_exceptions
@@ -61,6 +62,7 @@ logger = get_logger(__name__)
REQUEST_REPLY_PATHS_MAX = 3
PAYMENT_PATHS_MAX = 3
class NoRouteFound(Exception):
@@ -93,6 +95,7 @@ def create_blinded_path(
is_non_final_node = i < len(path) - 1
if is_non_final_node:
# spec: alt: short_channel_id instead of next_node_id
recipient_data = {
# TODO: SHOULD add padding data to ensure all encrypted_data_tlv(i) have the same length
'next_node_id': {'node_id': path[i+1]}
@@ -122,6 +125,16 @@ def create_blinded_path(
return blinded_path
def encode_blinded_path(blinded_path: dict):
with io.BytesIO() as blinded_path_fd:
OnionWireSerializer.write_field(
fd=blinded_path_fd,
field_type='blinded_path',
count=1,
value=blinded_path)
return blinded_path_fd.getvalue()
def blinding_privkey(privkey: bytes, blinding: bytes) -> bytes:
shared_secret = get_ecdh(privkey, blinding)
b_hmac = get_bolt04_onion_key(b'blinded_node_id', shared_secret)
@@ -371,35 +384,106 @@ def get_blinded_reply_paths(
max_paths: int = REQUEST_REPLY_PATHS_MAX,
preferred_node_id: bytes = None
) -> Sequence[dict]:
"""construct a list of blinded reply_paths.
"""construct a list of blinded reply-paths for onion message.
"""
mydata = {'path_id': {'data': path_id}} # same path_id used in every reply path
paths, payinfo = get_blinded_paths_to_me(lnwallet, mydata, max_paths=max_paths,
preferred_node_id=preferred_node_id, onion_message=True)
return paths
def get_blinded_paths_to_me(
lnwallet: 'LNWallet',
final_recipient_data: dict,
*,
max_paths: int = PAYMENT_PATHS_MAX,
preferred_node_id: bytes = None,
onion_message: bool = False
) -> Tuple[Sequence[dict], Sequence[dict]]:
"""construct a list of blinded paths.
current logic:
- uses current onion_message capable channel peers if exist
- otherwise, uses current onion_message capable peers
- uses channels peers if not onion_message
- uses current onion_message capable channel peers if exist and if onion_message
- otherwise, uses current onion_message capable peers if onion_message
- prefers preferred_node_id if given
- reply_path introduction points are direct peers only (TODO: longer reply paths)"""
- reply_path introduction points are direct peers only (TODO: longer paths)"""
# TODO: build longer paths and/or add dummy hops to increase privacy
my_active_channels = [chan for chan in lnwallet.channels.values() if chan.is_active()]
my_onionmsg_channels = [chan for chan in my_active_channels if lnwallet.lnpeermgr.get_peer_by_pubkey(chan.node_id) and
lnwallet.lnpeermgr.get_peer_by_pubkey(chan.node_id).their_features.supports(LnFeatures.OPTION_ONION_MESSAGE_OPT)]
my_onionmsg_peers = [peer for peer in lnwallet.lnpeermgr.peers.values() if peer.their_features.supports(LnFeatures.OPTION_ONION_MESSAGE_OPT)]
my_channels = my_active_channels
if onion_message:
my_channels = [chan for chan in my_active_channels if lnwallet.lnpeermgr.get_peer_by_pubkey(chan.node_id) and
lnwallet.lnpeermgr.get_peer_by_pubkey(chan.node_id).their_features.supports(LnFeatures.OPTION_ONION_MESSAGE_OPT)]
result = []
payinfo = []
mynodeid = lnwallet.node_keypair.pubkey
mydata = {'path_id': {'data': path_id}} # same path_id used in every reply path
if len(my_onionmsg_channels):
# randomize list, but prefer preferred_node_id
rchans = sorted(my_onionmsg_channels, key=lambda x: random() if x.node_id != preferred_node_id else 0)
for chan in rchans[:max_paths]:
blinded_path = create_blinded_path(os.urandom(32), [chan.node_id, mynodeid], mydata)
result.append(blinded_path)
elif len(my_onionmsg_peers):
# randomize list, but prefer preferred_node_id
rpeers = sorted(my_onionmsg_peers, key=lambda x: random() if x.pubkey != preferred_node_id else 0)
for peer in rpeers[:max_paths]:
blinded_path = create_blinded_path(os.urandom(32), [peer.pubkey, mynodeid], mydata)
result.append(blinded_path)
local_height = lnwallet.network.get_local_height()
return result
if len(my_channels):
# randomize list, but prefer preferred_node_id
rchans = sorted(my_channels, key=lambda x: random() if x.node_id != preferred_node_id else 0)
for chan in rchans[:max_paths]:
hop_extras = None
if not onion_message: # add hop_extras and payinfo, assumption: len(blinded_path) == 2 (us and peer)
# get policy
cp = get_mychannel_policy(chan.short_channel_id, chan.node_id, {chan.short_channel_id: chan})
dest_max_cltv_expiry = local_height + MAXIMUM_REMOTE_TO_SELF_DELAY_ACCEPTED
# TODO: for longer paths (>2), reverse traverse and calculate max_cltv_expiry at each intermediate hop
# and determine the cltv delta sums and fee sums of the hops for the payinfo struct.
# current assumption is len(blinded_path) == 2 (us and peer)
sum_cltv_expiry_delta = cp.cltv_delta
sum_fee_base_msat = cp.fee_base_msat
sum_fee_proportional_millionths = cp.fee_proportional_millionths
# path htlc limits
blinded_path_min_htlc_msat = cp.htlc_minimum_msat
blinded_path_max_htlc_msat = cp.htlc_maximum_msat
hop_extras = [{
# spec: MUST include encrypted_data_tlv.payment_relay for each non-final node.
'payment_relay': {
'cltv_expiry_delta': cp.cltv_delta,
'fee_base_msat': cp.fee_base_msat,
'fee_proportional_millionths': cp.fee_proportional_millionths,
},
# spec: MUST set encrypted_data_tlv.payment_constraints for each non-final node and MAY set it for the final node:
#
# max_cltv_expiry to the largest block height at which the route is allowed to be used, starting
# from the final node's chosen max_cltv_expiry height at which the route should expire, adding
# the final node's min_final_cltv_expiry_delta and then adding
# encrypted_data_tlv.payment_relay.cltv_expiry_delta at each hop.
#
# htlc_minimum_msat to the largest minimum HTLC value the nodes will allow.
'payment_constraints': {
'max_cltv_expiry': dest_max_cltv_expiry + cp.cltv_delta,
'htlc_minimum_msat': blinded_path_min_htlc_msat
}
}]
payinfo.append({
'fee_base_msat': sum_fee_base_msat,
'fee_proportional_millionths': sum_fee_proportional_millionths,
'cltv_expiry_delta': sum_cltv_expiry_delta + MIN_FINAL_CLTV_DELTA_ACCEPTED,
'htlc_minimum_msat': blinded_path_min_htlc_msat,
'htlc_maximum_msat': blinded_path_max_htlc_msat,
'flen': 0,
'features': bytes(0)
})
blinded_path = create_blinded_path(os.urandom(32), [chan.node_id, mynodeid], final_recipient_data,
hop_extras=hop_extras)
result.append(blinded_path)
elif onion_message:
# we can use peers even without channels for onion messages
my_onionmsg_peers = [peer for peer in lnwallet.lnpeermgr.peers.values() if
peer.their_features.supports(LnFeatures.OPTION_ONION_MESSAGE_OPT)]
if len(my_onionmsg_peers):
# randomize list, but prefer preferred_node_id
rpeers = sorted(my_onionmsg_peers, key=lambda x: random() if x.pubkey != preferred_node_id else 0)
for peer in rpeers[:max_paths]:
blinded_path = create_blinded_path(os.urandom(32), [peer.pubkey, mynodeid], final_recipient_data)
result.append(blinded_path)
return result, payinfo
class Timeout(Exception): pass