#!/usr/bin/env python3
"""Test plugin for adding inputs/outputs to a dual-funded transaction
"""
from pyln.client import Plugin, Millisatoshi
from pyln.proto import bech32_decode
from typing import Iterable, List, Optional
from wallycore import (
psbt_add_output_at,
psbt_find_input_unknown,
psbt_from_base64,
psbt_get_input_unknown,
psbt_get_num_inputs,
psbt_to_base64,
tx_output_init,
)
plugin = Plugin()
def convertbits(data: Iterable[int], frombits: int, tobits: int, pad: bool = True) -> Optional[List[int]]:
"""General power-of-2 base conversion."""
acc = 0
bits = 0
ret = []
maxv = (1 << tobits) - 1
max_acc = (1 << (frombits + tobits - 1)) - 1
for value in data:
if value < 0 or (value >> frombits):
return None
acc = ((acc << frombits) | value) & max_acc
bits += frombits
while bits >= tobits:
bits -= tobits
ret.append((acc >> bits) & maxv)
if pad:
if bits:
ret.append((acc << (tobits - bits)) & maxv)
elif bits >= frombits or ((acc << (tobits - bits)) & maxv):
return None
return ret
def get_script(bech_addr):
hrp, data = bech32_decode(bech_addr)
# FIXME: verify hrp matches expected network
wprog = convertbits(data[1:], 5, 8, False)
wit_ver = data[0]
if wit_ver > 16:
raise ValueError("Invalid witness version {}".format(wit_ver[0]))
return bytes([wit_ver + 0x50 if wit_ver > 0 else wit_ver, len(wprog)] + wprog)
def find_feerate(best, their_min, their_max, our_min, our_max):
if best >= our_min and best <= our_max:
return best
if their_max < our_min or their_min > our_max:
return False
if best < our_min:
return our_min
# best > our_max:
return our_max
def find_inputs(b64_psbt):
serial_id_key = bytes.fromhex('fc096c696768746e696e6701')
psbt = psbt_from_base64(b64_psbt)
input_idxs = []
for i in range(psbt_get_num_inputs(psbt)):
idx = psbt_find_input_unknown(psbt, i, serial_id_key)
if idx == 0:
continue
# returned index is off by one, so 0 can be 'not found'
serial_bytes = psbt_get_input_unknown(psbt, i, idx - 1)
serial_id = int.from_bytes(serial_bytes, byteorder='big', signed=False)
# We're the accepter, so our inputs have odd serials
if serial_id % 2:
input_idxs.append(i)
return input_idxs
@plugin.init()
def init(configuration, options, plugin):
# this is the max channel size, pre-wumbo
plugin.max_fund = Millisatoshi((2 ** 24 - 1) * 1000)
plugin.inflight = {}
plugin.log('max funding set to {}'.format(plugin.max_fund))
@plugin.method("setacceptfundingmax")
def set_accept_funding_max(plugin, max_sats, **kwargs):
plugin.max_fund = Millisatoshi(max_sats)
return {'accepter_max_funding': plugin.max_fund}
def add_inflight(plugin, peerid, chanid, psbt):
if peerid in plugin.inflight:
chans = plugin.inflight[peerid]
else:
chans = {}
plugin.inflight[peerid] = chans
if chanid in chans:
raise ValueError("channel {} already in flight (peer {})".format(chanid, peerid))
chans[chanid] = psbt
def cleanup_inflight(plugin, chanid):
for peer, chans in plugin.inflight.items():
if chanid in chans:
psbt = chans[chanid]
del chans[chanid]
return psbt
return None
def cleanup_inflight_peer(plugin, peerid):
if peerid in plugin.inflight:
chans = plugin.inflight[peerid]
for chanid, psbt in chans.items():
plugin.rpc.unreserveinputs(psbt)
del plugin.inflight[peerid]
@plugin.hook('openchannel2')
def on_openchannel(openchannel2, plugin, **kwargs):
# We mirror what the peer does, wrt to funding amount ...
amount = Millisatoshi(openchannel2['their_funding'])
locktime = openchannel2['locktime']
if amount > plugin.max_fund:
plugin.log("amount adjusted from {} to {}".format(amount, plugin.max_fund))
amount = plugin.max_fund
if amount == 0:
plugin.log("accepter_max_funding set to zero")
return {'result': 'continue'}
# ...unless they send us totally unacceptable feerates.
feerate = find_feerate(openchannel2['funding_feerate_best'],
openchannel2['funding_feerate_min'],
openchannel2['funding_feerate_max'],
openchannel2['feerate_our_min'],
openchannel2['feerate_our_max'])
# Their feerate range is out of bounds, we're not going to
# participate.
if not feerate:
plugin.log("Declining to fund, no feerate found.")
return {'result': 'continue'}
funding = plugin.rpc.fundpsbt(int(amount.to_satoshi()),
'{}perkw'.format(feerate),
0, # because we're the accepter!!
reserve=True,
locktime=locktime,
minconf=0,
min_witness_weight=110)
psbt_obj = psbt_from_base64(funding['psbt'])
excess = Millisatoshi(funding['excess_msat'])
change_cost = Millisatoshi(124 * feerate)
dust_limit = Millisatoshi(253 * 1000)
if excess > (dust_limit + change_cost):
addr = plugin.rpc.newaddr()['bech32']
change = excess - change_cost
output = tx_output_init(change.to_whole_satoshi(), get_script(addr))
psbt_add_output_at(psbt_obj, 0, 0, output)
psbt = psbt_to_base64(psbt_obj, 0)
add_inflight(plugin, openchannel2['id'],
openchannel2['channel_id'], psbt)
plugin.log("contributing {} at feerate {}".format(amount, feerate))
return {'result': 'continue', 'psbt': psbt,
'accepter_funding_msat': amount,
'funding_feerate': feerate}
@plugin.hook('openchannel2_changed')
def on_tx_changed(openchannel2_changed, plugin, **kwargs):
# In this example, we have nothing to add, so we
# pass back the same psbt that was forwarded in here
return {'result': 'continue', 'psbt': openchannel2_changed['psbt']}
@plugin.hook('openchannel2_sign')
def on_tx_sign(openchannel2_sign, plugin, **kwargs):
psbt = openchannel2_sign['psbt']
# We only sign the ones with our parity of a serial_id
input_idxs = find_inputs(psbt)
if len(input_idxs) > 0:
final_psbt = plugin.rpc.signpsbt(psbt, signonly=input_idxs)['signed_psbt']
else:
final_psbt = psbt
cleanup_inflight(plugin, openchannel2_sign['channel_id'])
return {'result': 'continue', 'psbt': final_psbt}
@plugin.subscribe("channel_open_failed")
def on_open_failed(channel_open_failed, plugin, **kwargs):
channel_id = channel_open_failed['channel_id']
psbt = cleanup_inflight(plugin, channel_id)
if psbt:
plugin.log("failed to open channel {}, unreserving".format(channel_id))
plugin.rpc.unreserveinputs(psbt)
@plugin.subscribe("disconnect")
def on_peer_disconnect(id, plugin, **kwargs):
plugin.log("peer {} disconnected, removing inflights".format(id))
cleanup_inflight_peer(plugin, id)
plugin.run()