swaps: code style clean-up, add type hints, force kwargs

no intended functional changes

electrum/crypto.py

@@ -330,7 +330,7 @@ def sha256d(x: Union[bytes, str]) -> bytes:
 def hash_160(x: bytes) -> bytes:
     return ripemd(sha256(x))
 
-def ripemd(x):
+def ripemd(x: bytes) -> bytes:
     try:
         md = hashlib.new('ripemd160')
         md.update(x)

electrum/gui/qml/qeswaphelper.py

@@ -2,7 +2,7 @@ import asyncio
 import concurrent
 import threading
 from enum import IntEnum
-from typing import Union
+from typing import Union, Optional
 
 from PyQt6.QtCore import pyqtProperty, pyqtSignal, pyqtSlot, QObject, QTimer, pyqtEnum
 
@@ -39,7 +39,7 @@ class QESwapHelper(AuthMixin, QObject, QtEventListener):
     def __init__(self, parent=None):
         super().__init__(parent)
 
-        self._wallet = None
+        self._wallet = None  # type: Optional[QEWallet]
         self._sliderPos = 0
         self._rangeMin = 0
         self._rangeMax = 0
@@ -377,8 +377,8 @@ class QESwapHelper(AuthMixin, QObject, QtEventListener):
                 self.state = QESwapHelper.State.Started
                 self._swap, invoice = fut.result()
 
-                tx = self._wallet.wallet.lnworker.swap_manager.create_funding_tx(self._swap, dummy_tx, self._wallet.password)
-                coro2 = self._wallet.wallet.lnworker.swap_manager.wait_for_htlcs_and_broadcast(self._swap, invoice, tx)
+                tx = self._wallet.wallet.lnworker.swap_manager.create_funding_tx(self._swap, dummy_tx, password=self._wallet.password)
+                coro2 = self._wallet.wallet.lnworker.swap_manager.wait_for_htlcs_and_broadcast(swap=self._swap, invoice=invoice, tx=tx)
                 self._fut_htlc_wait = fut = asyncio.run_coroutine_threadsafe(coro2, loop)
 
                 self.canCancel = True

electrum/gui/qt/send_tab.py

@@ -734,7 +734,7 @@ class SendTab(QWidget, MessageBoxMixin, Logger):
         if hasattr(tx, 'swap_payment_hash'):
             sm = self.wallet.lnworker.swap_manager
             swap = sm.get_swap(tx.swap_payment_hash)
-            coro = sm.wait_for_htlcs_and_broadcast(swap, tx.swap_invoice, tx)
+            coro = sm.wait_for_htlcs_and_broadcast(swap=swap, invoice=tx.swap_invoice, tx=tx)
             self.window.run_coroutine_dialog(
                 coro, _('Awaiting swap payment...'),
                 on_result=self.window.on_swap_result,

electrum/gui/qt/swap_dialog.py

@@ -330,8 +330,8 @@ class SwapDialog(WindowModalDialog, QtEventListener):
         except Exception as e:
             self.window.show_error(str(e))
             return
-        tx = sm.create_funding_tx(swap, dummy_tx, password)
-        coro2 = sm.wait_for_htlcs_and_broadcast(swap, invoice, tx)
+        tx = sm.create_funding_tx(swap, dummy_tx, password=password)
+        coro2 = sm.wait_for_htlcs_and_broadcast(swap=swap, invoice=invoice, tx=tx)
         self.window.run_coroutine_dialog(
             coro2, _('Awaiting swap payment...'),
             on_result=self.window.on_swap_result,

electrum/lnworker.py

@@ -1473,7 +1473,7 @@ class LNWallet(LNWorker):
     async def pay_invoice(
             self, invoice: str, *,
             amount_msat: int = None,
-            attempts: int = None, # used only in unit tests
+            attempts: int = None,  # used only in unit tests (and for swaps?!)
             full_path: LNPaymentPath = None,
             channels: Optional[Sequence[Channel]] = None,
     ) -> Tuple[bool, List[HtlcLog]]:

electrum/plugins/swapserver/server.py

@@ -106,7 +106,7 @@ class SwapServer(Logger, EventListener):
         assert len(their_pubkey) == 33
         swap = self.sm.create_reverse_swap(
             lightning_amount_sat=lightning_amount_sat,
-            their_pubkey=their_pubkey
+            their_pubkey=their_pubkey,
         )
         response = {
             "id": swap.payment_hash.hex(),

electrum/simple_config.py

@@ -813,6 +813,7 @@ class SimpleConfig(Logger):
     @classmethod
     def estimate_fee_for_feerate(cls, fee_per_kb: Union[int, float, Decimal],
                                  size: Union[int, float, Decimal]) -> int:
+        # note: 'size' is in vbytes
         size = Decimal(size)
         fee_per_kb = Decimal(fee_per_kb)
         fee_per_byte = fee_per_kb / 1000

electrum/submarine_swaps.py

@@ -1,7 +1,7 @@
 import asyncio
 import json
 import os
-from typing import TYPE_CHECKING, Optional, Dict, Union
+from typing import TYPE_CHECKING, Optional, Dict, Union, Sequence, Tuple
 from decimal import Decimal
 import math
 import time
@@ -9,6 +9,7 @@ import time
 import attr
 import aiohttp
 
+from . import lnutil
 from .crypto import sha256, hash_160
 from .ecc import ECPrivkey
 from .bitcoin import (script_to_p2wsh, opcodes, p2wsh_nested_script, push_script,
@@ -38,6 +39,7 @@ if TYPE_CHECKING:
     from .wallet import Abstract_Wallet
     from .lnwatcher import LNWalletWatcher
     from .lnworker import LNWallet
+    from .lnchannel import Channel
     from .simple_config import SimpleConfig
 
 
@@ -76,7 +78,16 @@ WITNESS_TEMPLATE_REVERSE_SWAP = [
     opcodes.OP_CHECKSIG
 ]
 
-def check_reverse_redeem_script(redeem_script, lockup_address, payment_hash, locktime, *, refund_pubkey=None, claim_pubkey=None):
+
+def check_reverse_redeem_script(
+    *,
+    redeem_script: str,
+    lockup_address: str,
+    payment_hash: bytes,
+    locktime: int,
+    refund_pubkey: bytes = None,
+    claim_pubkey: bytes = None,
+) -> None:
     redeem_script = bytes.fromhex(redeem_script)
     parsed_script = [x for x in script_GetOp(redeem_script)]
     if not match_script_against_template(redeem_script, WITNESS_TEMPLATE_REVERSE_SWAP):
@@ -91,7 +102,6 @@ def check_reverse_redeem_script(redeem_script, lockup_address, payment_hash, loc
         raise Exception("rswap check failed: our pubkey not in script")
     if locktime != int.from_bytes(parsed_script[10][1], byteorder='little'):
         raise Exception("rswap check failed: inconsistent locktime and script")
-    return parsed_script[7][1], parsed_script[13][1]
 
 
 class SwapServerError(Exception):
@@ -109,7 +119,7 @@ class SwapData(StoredObject):
     onchain_amount = attr.ib(type=int)  # in sats
     lightning_amount = attr.ib(type=int)  # in sats
     redeem_script = attr.ib(type=bytes, converter=hex_to_bytes)
-    preimage = attr.ib(type=bytes, converter=hex_to_bytes)
+    preimage = attr.ib(type=Optional[bytes], converter=hex_to_bytes)
     prepay_hash = attr.ib(type=Optional[bytes], converter=hex_to_bytes)
     privkey = attr.ib(type=bytes, converter=hex_to_bytes)
     lockup_address = attr.ib(type=str)
@@ -349,6 +359,7 @@ class SwapManager(Logger):
         return self.get_fee(CLAIM_FEE_SIZE)
 
     def get_fee(self, size):
+        # note: 'size' is in vbytes
         return self._get_fee(size=size, config=self.wallet.config)
 
     @classmethod
@@ -376,15 +387,16 @@ class SwapManager(Logger):
             if swap.funding_txid is None:
                 password = self.wallet.get_unlocked_password()
                 for batch_rbf in [True, False]:
-                    tx = self.create_funding_tx(swap, None, password, batch_rbf=batch_rbf)
+                    tx = self.create_funding_tx(swap, None, password=password, batch_rbf=batch_rbf)
                     try:
                         await self.broadcast_funding_tx(swap, tx)
                     except TxBroadcastServerReturnedError:
                         continue
                     break
 
-    def create_normal_swap(self, *, lightning_amount_sat=None, payment_hash: bytes=None, their_pubkey=None):
+    def create_normal_swap(self, *, lightning_amount_sat: int, payment_hash: bytes, their_pubkey: bytes = None):
         """ server method """
+        assert lightning_amount_sat
         locktime = self.network.get_local_height() + LOCKTIME_DELTA_REFUND
         our_privkey = os.urandom(32)
         our_pubkey = ECPrivkey(our_privkey).get_public_key_bytes(compressed=True)
@@ -400,8 +412,6 @@ class SwapManager(Logger):
             lightning_amount_sat=lightning_amount_sat,
             payment_hash=payment_hash,
             our_privkey=our_privkey,
-            their_pubkey=their_pubkey,
-            invoice=None,
             prepay=True,
         )
         self.lnworker.register_hold_invoice(payment_hash, self.hold_invoice_callback)
@@ -409,35 +419,32 @@ class SwapManager(Logger):
 
     def add_normal_swap(
             self, *,
-            redeem_script=None,
-            locktime=None,
-            onchain_amount_sat=None,
-            lightning_amount_sat=None,
-            payment_hash=None,
-            our_privkey=None,
-            their_pubkey=None,
-            invoice=None,
-            prepay=None,
-            channels=None,
-    ):
-        """ if invoice is None, create a hold invoice """
+            redeem_script: str,
+            locktime: int,  # onchain
+            onchain_amount_sat: int,
+            lightning_amount_sat: int,
+            payment_hash: bytes,
+            our_privkey: bytes,
+            prepay: bool,
+            channels: Optional[Sequence['Channel']] = None,
+    ) -> Tuple[SwapData, str, str]:
+        """creates a hold invoice"""
         if prepay:
             prepay_amount_sat = self.get_claim_fee() * 2
             invoice_amount_sat = lightning_amount_sat - prepay_amount_sat
         else:
             invoice_amount_sat = lightning_amount_sat
 
-        if not invoice:
-            _, invoice = self.lnworker.get_bolt11_invoice(
-                payment_hash=payment_hash,
-                amount_msat=invoice_amount_sat * 1000,
-                message='Submarine swap',
-                expiry=300,
-                fallback_address=None,
-                channels=channels,
-            )
-            # add payment info to lnworker
-            self.lnworker.add_payment_info_for_hold_invoice(payment_hash, invoice_amount_sat)
+        _, invoice = self.lnworker.get_bolt11_invoice(
+            payment_hash=payment_hash,
+            amount_msat=invoice_amount_sat * 1000,
+            message='Submarine swap',
+            expiry=300,
+            fallback_address=None,
+            channels=channels,
+        )
+        # add payment info to lnworker
+        self.lnworker.add_payment_info_for_hold_invoice(payment_hash, invoice_amount_sat)
 
         if prepay:
             prepay_hash = self.lnworker.create_payment_info(amount_msat=prepay_amount_sat*1000)
@@ -477,14 +484,14 @@ class SwapManager(Logger):
         self.add_lnwatcher_callback(swap)
         return swap, invoice, prepay_invoice
 
-    def create_reverse_swap(self, *, lightning_amount_sat=None, their_pubkey=None):
+    def create_reverse_swap(self, *, lightning_amount_sat: int, their_pubkey: bytes) -> SwapData:
         """ server method. """
+        assert lightning_amount_sat is not None
         locktime = self.network.get_local_height() + LOCKTIME_DELTA_REFUND
         privkey = os.urandom(32)
         our_pubkey = ECPrivkey(privkey).get_public_key_bytes(compressed=True)
         onchain_amount_sat = self._get_send_amount(lightning_amount_sat, is_reverse=False)
         preimage = os.urandom(32)
-        assert lightning_amount_sat is not None
         payment_hash = sha256(preimage)
         redeem_script = construct_script(
             WITNESS_TEMPLATE_REVERSE_SWAP,
@@ -501,7 +508,18 @@ class SwapManager(Logger):
             lightning_amount_sat=lightning_amount_sat)
         return swap
 
-    def add_reverse_swap(self, *, redeem_script=None, locktime=None, privkey=None, lightning_amount_sat=None, onchain_amount_sat=None, preimage=None, payment_hash=None, prepay_hash=None):
+    def add_reverse_swap(
+        self,
+        *,
+        redeem_script: str,
+        locktime: int,  # onchain
+        privkey: bytes,
+        lightning_amount_sat: int,
+        onchain_amount_sat: int,
+        preimage: bytes,
+        payment_hash: bytes,
+        prepay_hash: Optional[bytes] = None,
+    ) -> SwapData:
         lockup_address = script_to_p2wsh(redeem_script)
         receive_address = self.wallet.get_receiving_address()
         swap = SwapData(
@@ -526,7 +544,7 @@ class SwapManager(Logger):
         self.add_lnwatcher_callback(swap)
         return swap
 
-    def add_invoice(self, invoice, pay_now=False):
+    def add_invoice(self, invoice: str, pay_now: bool = False) -> None:
         invoice = Invoice.from_bech32(invoice)
         key = invoice.rhash
         payment_hash = bytes.fromhex(key)
@@ -548,28 +566,41 @@ class SwapManager(Logger):
             password,
             tx: PartialTransaction = None,
             channels = None,
-    ) -> str:
+    ) -> Optional[str]:
         """send on-chain BTC, receive on Lightning
 
+        Old (removed) flow:
         - User generates an LN invoice with RHASH, and knows preimage.
         - User creates on-chain output locked to RHASH.
         - Server pays LN invoice. User reveals preimage.
         - Server spends the on-chain output using preimage.
 
         New flow:
-         - user requests swap
-         - server creates preimage, sends RHASH to user
-         - user creates hold invoice, sends it to server
-
+         - User requests swap
+         - Server creates preimage, sends RHASH to user
+         - User creates hold invoice, sends it to server
+         - Server sends HTLC, user holds it
+         - User creates on-chain output locked to RHASH
+         - Server spends the on-chain output using preimage (revealing the preimage)
+         - User fulfills HTLC using preimage
         """
         assert self.network
         assert self.lnwatcher
-        swap, invoice = await self.request_normal_swap(lightning_amount_sat, expected_onchain_amount_sat, channels=channels)
-        tx = self.create_funding_tx(swap, tx, password)
-        return await self.wait_for_htlcs_and_broadcast(swap, invoice, tx)
+        swap, invoice = await self.request_normal_swap(
+            lightning_amount_sat=lightning_amount_sat,
+            expected_onchain_amount_sat=expected_onchain_amount_sat,
+            channels=channels,
+        )
+        tx = self.create_funding_tx(swap, tx, password=password)
+        return await self.wait_for_htlcs_and_broadcast(swap=swap, invoice=invoice, tx=tx)
 
-    async def request_normal_swap(self, lightning_amount_sat, expected_onchain_amount_sat, channels=None):
-        amount_msat = lightning_amount_sat * 1000
+    async def request_normal_swap(
+        self,
+        *,
+        lightning_amount_sat: int,
+        expected_onchain_amount_sat: int,
+        channels: Optional[Sequence['Channel']] = None,
+    ) -> Tuple[SwapData, str]:
         refund_privkey = os.urandom(32)
         refund_pubkey = ECPrivkey(refund_privkey).get_public_key_bytes(compressed=True)
 
@@ -585,8 +616,6 @@ class SwapManager(Logger):
             timeout=30)
         data = json.loads(response)
         payment_hash = bytes.fromhex(data["preimageHash"])
-        preimage = None
-        invoice = None
 
         zeroconf = data["acceptZeroConf"]
         onchain_amount = data["expectedAmount"]
@@ -594,7 +623,13 @@ class SwapManager(Logger):
         lockup_address = data["address"]
         redeem_script = data["redeemScript"]
         # verify redeem_script is built with our pubkey and preimage
-        claim_pubkey, _ = check_reverse_redeem_script(redeem_script, lockup_address, payment_hash, locktime, refund_pubkey=refund_pubkey)
+        check_reverse_redeem_script(
+            redeem_script=redeem_script,
+            lockup_address=lockup_address,
+            payment_hash=payment_hash,
+            locktime=locktime,
+            refund_pubkey=refund_pubkey,
+        )
 
         # check that onchain_amount is not more than what we estimated
         if onchain_amount > expected_onchain_amount_sat:
@@ -611,14 +646,18 @@ class SwapManager(Logger):
             onchain_amount_sat=onchain_amount,
             payment_hash=payment_hash,
             our_privkey=refund_privkey,
-            their_pubkey=claim_pubkey,
-            invoice=invoice,
             prepay=False,
             channels=channels,
         )
         return swap, invoice
 
-    async def wait_for_htlcs_and_broadcast(self, swap, invoice, tx):
+    async def wait_for_htlcs_and_broadcast(
+        self,
+        *,
+        swap: SwapData,
+        invoice: str,
+        tx: Transaction,
+    ) -> Optional[str]:
         payment_hash = swap.payment_hash
         refund_pubkey = ECPrivkey(swap.privkey).get_public_key_bytes(compressed=True)
         async def callback(payment_hash):
@@ -644,7 +683,14 @@ class SwapManager(Logger):
             await asyncio.sleep(0.1)
         return swap.funding_txid
 
-    def create_funding_tx(self, swap, tx, password, *, batch_rbf: Optional[bool] = None):
+    def create_funding_tx(
+        self,
+        swap: SwapData,
+        tx: Optional[PartialTransaction],
+        *,
+        password,
+        batch_rbf: Optional[bool] = None,
+    ) -> PartialTransaction:
         # create funding tx
         # note: rbf must not decrease payment
         # this is taken care of in wallet._is_rbf_allowed_to_touch_tx_output
@@ -663,7 +709,7 @@ class SwapManager(Logger):
         return tx
 
     @log_exceptions
-    async def request_swap_for_tx(self, tx: 'PartialTransaction'):
+    async def request_swap_for_tx(self, tx: 'PartialTransaction') -> Optional[Tuple[SwapData, str, PartialTransaction]]:
         for o in tx.outputs():
             if o.address == self.dummy_address:
                 change_amount = o.value
@@ -679,7 +725,7 @@ class SwapManager(Logger):
         return swap, invoice, tx
 
     @log_exceptions
-    async def broadcast_funding_tx(self, swap, tx):
+    async def broadcast_funding_tx(self, swap: SwapData, tx: Transaction) -> None:
         swap.funding_txid = tx.txid()
         await self.network.broadcast_transaction(tx)
 
@@ -688,7 +734,7 @@ class SwapManager(Logger):
             *,
             lightning_amount_sat: int,
             expected_onchain_amount_sat: int,
-            channels = None,
+            channels: Optional[Sequence['Channel']] = None,
     ) -> Optional[str]:
         """send on Lightning, receive on-chain
 
@@ -729,7 +775,14 @@ class SwapManager(Logger):
         onchain_amount = data["onchainAmount"]
         response_id = data['id']
         # verify redeem_script is built with our pubkey and preimage
-        check_reverse_redeem_script(redeem_script, lockup_address, payment_hash, locktime, refund_pubkey=None, claim_pubkey=our_pubkey)
+        check_reverse_redeem_script(
+            redeem_script=redeem_script,
+            lockup_address=lockup_address,
+            payment_hash=payment_hash,
+            locktime=locktime,
+            refund_pubkey=None,
+            claim_pubkey=our_pubkey,
+        )
         # check that the onchain amount is what we expected
         if onchain_amount < expected_onchain_amount_sat:
             raise Exception(f"rswap check failed: onchain_amount is less than what we expected: "