AaronFiore/electrum
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swaps: fix normal amount formulas

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In a normal (forward) swap (onchain->offchain):
send_amount = receive_amount * (1 + service_percentage) + normal_fee ,
and vice versa:
receive_amount = (send_amount + normal_fee) / (1 + service_percentage) ,
i.e., the service fee is charged on the received offchain amount.
This commit is contained in:
bitromortac
2020-12-11 10:44:23 +01:00
parent c377694347
commit 64ecf8539a
1 changed files with 10 additions and 10 deletions
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20
electrum/submarine_swaps.py
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@@ -281,7 +281,7 @@ class SwapManager(Logger):
if locktime - self.network.get_local_height() >= 144:
raise Exception("fswap check failed: locktime too far in future")
# create funding tx
funding_output = PartialTxOutput.from_address_and_value(lockup_address, expected_onchain_amount)
funding_output = PartialTxOutput.from_address_and_value(lockup_address, onchain_amount)
if tx is None:
tx = self.wallet.create_transaction(outputs=[funding_output], rbf=False, password=password)
else:
@@ -310,7 +310,7 @@ class SwapManager(Logger):
await self.network.broadcast_transaction(tx)
return tx.txid()
async def reverse_swap(self, amount_sat: int, expected_amount: int) -> bool:
async def reverse_swap(self, lightning_amount: int, expected_onchain_amount: int) -> bool:
"""send on Lightning, receive on-chain
- User generates preimage, RHASH. Sends RHASH to server.
@@ -330,7 +330,7 @@ class SwapManager(Logger):
"type": "reversesubmarine",
"pairId": "BTC/BTC",
"orderSide": "buy",
"invoiceAmount": amount_sat,
"invoiceAmount": lightning_amount,
"preimageHash": preimage_hash.hex(),
"claimPublicKey": pubkey.hex()
}
@@ -361,9 +361,9 @@ class SwapManager(Logger):
if locktime != int.from_bytes(parsed_script[10][1], byteorder='little'):
raise Exception("rswap check failed: inconsistent locktime and script")
# check that the onchain amount is what we expected
if onchain_amount < expected_amount:
if onchain_amount < expected_onchain_amount:
raise Exception(f"rswap check failed: onchain_amount is less than what we expected: "
f"{onchain_amount} < {expected_amount}")
f"{onchain_amount} < {expected_onchain_amount}")
# verify that we will have enough time to get our tx confirmed
if locktime - self.network.get_local_height() <= 60:
raise Exception("rswap check failed: locktime too close")
@@ -379,9 +379,9 @@ class SwapManager(Logger):
prepay_hash = fee_lnaddr.paymenthash
else:
prepay_hash = None
if int(invoice_amount) != amount_sat:
if int(invoice_amount) != lightning_amount:
raise Exception(f"rswap check failed: invoice_amount ({invoice_amount}) "
f"not what we requested ({amount_sat})")
f"not what we requested ({lightning_amount})")
# save swap data to wallet file
swap = SwapData(
redeem_script = redeem_script,
@@ -391,7 +391,7 @@ class SwapManager(Logger):
prepay_hash = prepay_hash,
lockup_address = lockup_address,
onchain_amount = onchain_amount,
lightning_amount = amount_sat,
lightning_amount = lightning_amount,
is_reverse = True,
is_redeemed = False,
funding_txid = None,
@@ -443,7 +443,7 @@ class SwapManager(Logger):
return
else:
x -= self.normal_fee
x = int(x * (100 - self.percentage) / 100)
x = int(x / ((100 + self.percentage) / 100))
if not self.check_invoice_amount(x):
return
return x
@@ -461,7 +461,7 @@ class SwapManager(Logger):
else:
if not self.check_invoice_amount(x):
return
x = int(x * 100 / (100 - self.percentage)) + 1
x = int(x * 100 / (100 + self.percentage)) + 1
x += self.normal_fee
return x