tests: plugin for dual-funding tests in ln-prototest

FIXME: requires wallycore

contrib/pyln-proto/pyln/proto/__init__.py

@@ -1,3 +1,4 @@
+from .bech32 import bech32_decode
 from .invoice import Invoice
 from .onion import OnionPayload, TlvPayload, LegacyOnionPayload
 from .wire import LightningConnection, LightningServerSocket
@@ -11,4 +12,5 @@ __all__ = [
     "OnionPayload",
     "LegacyOnionPayload",
     "TlvPayload",
+    "bech32_decode",
 ]

tests/plugins/df_accepter.py

@@ -0,0 +1,91 @@
+#!/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_from_base64, 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)
+
+
+@plugin.hook('openchannel2')
+def on_openchannel(openchannel2, plugin, **kwargs):
+    # We mirror what the peer does, wrt to funding amount
+    amount = openchannel2['their_funding']
+    feerate = openchannel2['feerate_per_kw_funding']
+    locktime = openchannel2['locktime']
+
+    funding = plugin.rpc.fundpsbt(amount, ''.join([str(feerate), 'perkw']), 0, reserve=True,
+                                  locktime=locktime)
+    psbt_obj = psbt_from_base64(funding['psbt'])
+
+    excess = Millisatoshi(funding['excess_msat'])
+    change_cost = Millisatoshi(164 * feerate // 1000 * 1000)
+    dust_limit = Millisatoshi(253 * 1000)
+    if excess > (dust_limit + change_cost):
+        addr = plugin.rpc.newaddr()['bech32']
+        change = excess - change_cost
+        output = tx_output_init(int(change.to_satoshi()), get_script(addr))
+        psbt_add_output_at(psbt_obj, 0, 0, output)
+
+    return {'result': 'continue', 'psbt': psbt_to_base64(psbt_obj, 0),
+            'accepter_funding_msat': amount}
+
+
+@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
+    # FIXME: find the inputs with an odd-serial, these are ours
+    # the key for a serial_id ::
+    our_inputs = [1]
+
+    signed_psbt = plugin.rpc.signpsbt(psbt, signonly=our_inputs)['signed_psbt']
+    return {'result': 'continue', 'psbt': signed_psbt}
+
+
+plugin.run()