Check Esplora Merkle leaf risk by base size

Esplora confirmation checks must use the non-witness transaction size
for the 64-byte Merkle leaf guard. Witness padding can otherwise raise
total_size without changing the serialization hashed into the txid and
Merkle tree.

Co-Authored-By: HAL 9000

This finding was discovered by Project Loupe

Author: tnull

lightning-transaction-sync/src/esplora.rs

@@ -5,7 +5,7 @@
 // http://opensource.org/licenses/MIT>, at your option. You may not use this file except in
 // accordance with one or both of these licenses.
 
-use crate::common::{ConfirmedTx, FilterQueue, SyncState};
+use crate::common::{is_potentially_unsafe_merkle_leaf, ConfirmedTx, FilterQueue, SyncState};
 use crate::error::{InternalError, TxSyncError};
 
 use lightning::chain::WatchedOutput;
@@ -393,7 +393,7 @@ impl<L: Logger> EsploraSyncClient<L> {
 				// https://web.archive.org/web/20240329003521/https://bitslog.com/2018/06/09/leaf-node-weakness-in-bitcoin-merkle-tree-design/).
 				// To protect against this (highly unlikely) attack vector, we check that the
 				// transaction is at least 65 bytes in length.
-				if tx.total_size() == 64 {
+				if is_potentially_unsafe_merkle_leaf(&tx) {
 					log_error!(
 						self.logger,
 						"Skipping transaction {} due to retrieving potentially invalid tx data.",