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wallet: fix get_locktime_for_new_transaction for lagging server

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Merchant reported that 0.5% of txs they make are rejected
by the connected server due to the locktime being in the future.

fixes https://github.com/spesmilo/electrum/issues/8245
This commit is contained in:
SomberNight
2023-03-20 15:50:38 +00:00
parent 4ed69cc54f
commit b8d4ccd432
1 changed files with 10 additions and 1 deletions
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11
electrum/wallet.py
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@@ -207,12 +207,21 @@ def get_locktime_for_new_transaction(network: 'Network') -> int:
chain = network.blockchain()
if chain.is_tip_stale():
return 0
# figure out current block height
chain_height = chain.height() # learnt from all connected servers, SPV-checked
server_height = network.get_server_height() # height claimed by main server, unverified
# note: main server might be lagging (either is slow, is malicious, or there is an SPV-invisible-hard-fork)
# - if it's lagging too much, it is the network's job to switch away
if server_height < chain_height - 10:
# the diff is suspiciously large... give up and use something non-fingerprintable
return 0
# discourage "fee sniping"
locktime = chain.height()
locktime = min(chain_height, server_height)
# sometimes pick locktime a bit further back, to help privacy
# of setups that need more time (offline/multisig/coinjoin/...)
if random.randint(0, 9) == 0:
locktime = max(0, locktime - random.randint(0, 99))
locktime = max(0, locktime)
return locktime