From f5079a06eed137eaba1766a946bd3dfaa1abe78c Mon Sep 17 00:00:00 2001 From: benthecarman Date: Sun, 24 Sep 2023 22:17:33 -0500 Subject: [PATCH] Use bitcoin core's logic for anti-fee-sniping --- src/sweep.rs | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/src/sweep.rs b/src/sweep.rs index ad1e9ef..94120f9 100644 --- a/src/sweep.rs +++ b/src/sweep.rs @@ -12,6 +12,7 @@ use lightning::util::ser::{Readable, WithoutLength}; use bitcoin::secp256k1::Secp256k1; use bitcoin::{LockTime, PackedLockTime}; +use rand::{thread_rng, Rng}; use crate::hex_utils; use crate::BitcoindClient; @@ -111,7 +112,19 @@ pub(crate) async fn periodic_sweep( bitcoind_client.get_est_sat_per_1000_weight(ConfirmationTarget::Background); // We set nLockTime to the current height to discourage fee sniping. - let cur_height = channel_manager.current_best_block().height(); + // Occasionally randomly pick a nLockTime even further back, so + // that transactions that are delayed after signing for whatever reason, + // e.g. high-latency mix networks and some CoinJoin implementations, have + // better privacy. + // Logic copied from core: https://github.com/bitcoin/bitcoin/blob/1d4846a8443be901b8a5deb0e357481af22838d0/src/wallet/spend.cpp#L936 + let mut cur_height = channel_manager.current_best_block().height(); + + // 10% of the time + if thread_rng().gen_range(0, 10) == 0 { + // subtract random number between 0 and 100 + cur_height = cur_height.saturating_sub(thread_rng().gen_range(0, 100)); + } + let locktime: PackedLockTime = LockTime::from_height(cur_height).map_or(PackedLockTime::ZERO, |l| l.into()); -- 2.39.5