From: Matt Corallo <git@bluematt.me>
Date: Thu, 10 Nov 2022 01:01:31 +0000 (+0000)
Subject: Handle `transaction_unconfirmed` as a full reorg to the tx height
X-Git-Tag: v0.0.113~34^2
X-Git-Url: http://git.bitcoin.ninja/?a=commitdiff_plain;h=refs%2Fheads%2F2022-11-more-robust-unconfirmed;p=rust-lightning

Handle `transaction_unconfirmed` as a full reorg to the tx height

In `ChannelMonitor`, if we see a `transaction_unconfirmed` for a
transaction we last saw in a block at height X, we shouldn't
*only* remove the `onchain_events_awaiting_threshold_conf` entry
for the given tx but rather for all transactions that we last saw
at height >= X.

This avoids any potential `onchain_events_awaiting_threshold_conf`
inconsistencies due to the order in whcih users mark transactions
unconfirmed (which the `chain::Confirm` docs do not currently set
any requirements on).

This also matches the `OnchainTxHandler` behavior, which does the
same lookup.
---

diff --git a/lightning/src/chain/channelmonitor.rs b/lightning/src/chain/channelmonitor.rs
index 0bfd94445..1933a3f52 100644
--- a/lightning/src/chain/channelmonitor.rs
+++ b/lightning/src/chain/channelmonitor.rs
@@ -3111,10 +3111,24 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		F::Target: FeeEstimator,
 		L::Target: Logger,
 	{
-		self.onchain_events_awaiting_threshold_conf.retain(|ref entry| if entry.txid == *txid {
-			log_info!(logger, "Removing onchain event with txid {}", txid);
-			false
-		} else { true });
+		let mut removed_height = None;
+		for entry in self.onchain_events_awaiting_threshold_conf.iter() {
+			if entry.txid == *txid {
+				removed_height = Some(entry.height);
+				break;
+			}
+		}
+
+		if let Some(removed_height) = removed_height {
+			log_info!(logger, "transaction_unconfirmed of txid {} implies height {} was reorg'd out", txid, removed_height);
+			self.onchain_events_awaiting_threshold_conf.retain(|ref entry| if entry.height >= removed_height {
+				log_info!(logger, "Transaction {} reorg'd out", entry.txid);
+				false
+			} else { true });
+		}
+
+		debug_assert!(!self.onchain_events_awaiting_threshold_conf.iter().any(|ref entry| entry.txid == *txid));
+
 		self.onchain_tx_handler.transaction_unconfirmed(txid, broadcaster, fee_estimator, logger);
 	}