commit 1e67e55303987aa643018a314c1245be597286ef
parent 368229a4c37bb57bdff188be4e9ec59bde7441ee
Author: ThomasV <thomasv@electrum.org>
Date: Tue, 19 May 2020 13:23:44 +0200
submarine swaps, initial implementation:
- server uses Boltz API (https://docs.boltz.exchange/en/latest/)
- reverse swaps only
- command-line only
Diffstat:
2 files changed, 164 insertions(+), 0 deletions(-)
diff --git a/electrum/commands.py b/electrum/commands.py
@@ -1100,6 +1100,16 @@ class Commands:
""" return the local watchtower's ctn of channel. used in regtests """
return await self.network.local_watchtower.sweepstore.get_ctn(channel_point, None)
+ @command('wn')
+ async def reverse_swap(self, amount, wallet: Abstract_Wallet = None):
+ from .submarine_swaps import reverse_swap
+ amount_sat = satoshis(amount)
+ return await reverse_swap(amount_sat, wallet, self.network)
+
+ @command('wn')
+ async def claim_swap(self, key, wallet: Abstract_Wallet = None):
+ from .submarine_swaps import claim_swap
+ return await claim_swap(key, wallet)
def eval_bool(x: str) -> bool:
if x == 'false': return False
diff --git a/electrum/submarine_swaps.py b/electrum/submarine_swaps.py
@@ -0,0 +1,154 @@
+import asyncio
+import json
+import os
+from .crypto import sha256, hash_160
+from .ecc import ECPrivkey
+from .bitcoin import address_to_script, script_to_p2wsh, opcodes
+from .transaction import TxOutpoint, PartialTxInput, PartialTxOutput, PartialTransaction, construct_witness
+from .transaction import script_GetOp, match_script_against_template, OPPushDataGeneric, OPPushDataPubkey
+from .transaction import Transaction
+from .util import log_exceptions
+
+
+# todo:
+# - integrate with lnwatcher
+# - forward swaps
+
+API_URL = 'http://ecdsa.org:9001'
+
+WITNESS_TEMPLATE_SWAP = [
+ opcodes.OP_SIZE,
+ OPPushDataGeneric(None),
+ opcodes.OP_EQUAL,
+ opcodes.OP_IF,
+ opcodes.OP_HASH160,
+ OPPushDataGeneric(lambda x: x == 20),
+ opcodes.OP_EQUALVERIFY,
+ OPPushDataPubkey,
+ opcodes.OP_ELSE,
+ opcodes.OP_DROP,
+ OPPushDataGeneric(None),
+ opcodes.OP_CHECKLOCKTIMEVERIFY,
+ opcodes.OP_DROP,
+ OPPushDataPubkey,
+ opcodes.OP_ENDIF,
+ opcodes.OP_CHECKSIG
+]
+
+
+def create_claim_tx(txid, index, witness_script, preimage, privkey:bytes, amount_sat, address, fee):
+ pubkey = ECPrivkey(privkey).get_public_key_bytes(compressed=True)
+ prevout = TxOutpoint(txid=bytes.fromhex(txid), out_idx=index)
+ txin = PartialTxInput(prevout=prevout)
+ txin.script_type = 'p2wsh'
+ txin.script_sig = b''
+ txin.pubkeys = [pubkey]
+ txin.num_sig = 1
+ txin.witness_script = witness_script
+ txin._trusted_value_sats = amount_sat
+ txout = PartialTxOutput(scriptpubkey=bytes.fromhex(address_to_script(address)), value=amount_sat - fee)
+ tx = PartialTransaction.from_io([txin], [txout], version=2)
+ sig = bytes.fromhex(tx.sign_txin(0, privkey))
+ witness = construct_witness([sig, preimage, witness_script])
+ tx.inputs()[0].witness = bytes.fromhex(witness)
+ assert tx.is_complete()
+ return tx
+
+
+@log_exceptions
+async def _claim_swap(lnworker, lockup_address, redeem_script, preimage, privkey, onchain_amount, address):
+ # add address to lnwatcher
+ lnwatcher = lnworker.lnwatcher
+ lnwatcher.add_address(lockup_address)
+ while True:
+ h = lnwatcher.get_address_history(lockup_address)
+ if not h:
+ await asyncio.sleep(1)
+ continue
+ for txid, height in h:
+ tx = lnwatcher.db.get_transaction(txid)
+ # find relevant output
+ for i, o in enumerate(tx.outputs()):
+ if o.address == lockup_address:
+ break
+ else:
+ continue
+ # create claim tx
+ fee = lnwatcher.config.estimate_fee(136, allow_fallback_to_static_rates=True)
+ tx = create_claim_tx(txid, i, redeem_script, preimage, privkey, onchain_amount, address, fee)
+ try:
+ await lnwatcher.network.broadcast_transaction(tx)
+ break
+ except:
+ continue
+
+async def claim_swap(key, wallet):
+ lnworker = wallet.lnworker
+ address = wallet.get_unused_address()
+ swaps = wallet.db.get_dict('submarine_swaps')
+ data = swaps[key]
+ onchain_amount = data['onchainAmount']
+ redeem_script = bytes.fromhex(data['redeemScript'])
+ lockup_address = data['lockupAddress']
+ preimage = bytes.fromhex(data['preimage'])
+ privkey = bytes.fromhex(data['privkey'])
+ await _claim_swap(lnworker, lockup_address, redeem_script, preimage, privkey, onchain_amount, address)
+
+@log_exceptions
+async def reverse_swap(amount_sat, wallet: 'Abstract_Wallet', network: 'Network'):
+ privkey = os.urandom(32)
+ pubkey = ECPrivkey(privkey).get_public_key_bytes(compressed=True)
+ preimage = os.urandom(32)
+ preimage_hash = sha256(preimage)
+ address = wallet.get_unused_address()
+ request_data = {
+ "type": "reversesubmarine",
+ "pairId": "BTC/BTC",
+ "orderSide": "buy",
+ "invoiceAmount": amount_sat,
+ "preimageHash": preimage_hash.hex(),
+ "claimPublicKey": pubkey.hex()
+ }
+ response = await network._send_http_on_proxy(
+ 'post',
+ API_URL + '/createswap',
+ json=request_data,
+ timeout=30)
+ data = json.loads(response)
+ invoice = data['invoice']
+ lockup_address = data['lockupAddress']
+ redeem_script = data['redeemScript']
+ timeout_block_height = data['timeoutBlockHeight']
+ onchain_amount = data["onchainAmount"]
+ response_id = data['id']
+ # verify redeem_script is built with our pubkey and preimage
+ redeem_script = bytes.fromhex(redeem_script)
+ parsed_script = [x for x in script_GetOp(redeem_script)]
+ assert match_script_against_template(redeem_script, WITNESS_TEMPLATE_SWAP)
+ assert script_to_p2wsh(redeem_script.hex()) == lockup_address
+ assert hash_160(preimage) == parsed_script[5][1]
+ assert pubkey == parsed_script[7][1]
+ # verify that we will have enought time to get our tx confirmed
+ cltv = int.from_bytes(parsed_script[10][1], byteorder='little')
+ assert cltv - network.get_local_height() > 10
+ # verify invoice preimage_hash
+ lnworker = wallet.lnworker
+ lnaddr = lnworker._check_invoice(invoice, amount_sat)
+ assert lnaddr.paymenthash == preimage_hash
+ # save swap data in wallet in case payment fails
+ data['privkey'] = privkey.hex()
+ data['preimage'] = preimage.hex()
+ # save data to wallet file
+ swaps = wallet.db.get_dict('submarine_swaps')
+ swaps[response_id] = data
+ # add to lnwatcher
+ f = asyncio.ensure_future(_claim_swap(lnworker, lockup_address, redeem_script, preimage, privkey, onchain_amount, address))
+ # initiate payment.
+ success, log = await lnworker._pay(invoice, attempts=1)
+ # discard data; this should be done by lnwatcher
+ if success:
+ swaps.pop(response_id)
+ return {
+ 'id':response_id,
+ 'success':success,
+ }
