From a589daa2353ffdd01385245c5d0a04d70b89ec71 Mon Sep 17 00:00:00 2001
From: darosior <darosior@protonmail.com>
Date: Thu, 30 Jan 2020 12:56:27 +0100
Subject: [PATCH] wallet: fuzz the nLockTime added to withdraw transactions

---
 wallet/walletrpc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/wallet/walletrpc.c b/wallet/walletrpc.c
index 06220e0f2..dbef2a874 100644
--- a/wallet/walletrpc.c
+++ b/wallet/walletrpc.c
@@ -10,6 +10,7 @@
 #include <common/jsonrpc_errors.h>
 #include <common/key_derive.h>
 #include <common/param.h>
+#include <common/pseudorand.h>
 #include <common/status.h>
 #include <common/utils.h>
 #include <common/utxo.h>
@@ -288,9 +289,11 @@ static struct command_result *json_prepare_tx(struct command *cmd,
 		 *   native segwit, nlocktime set to tip, and sequence set to
 		 *   0xFFFFFFFE by default. Other wallets are likely to implement
 		 *   this too).
-		 * FIXME: Do we want to also fuzz this like bitcoind does ?
 		 */
 		locktime = cmd->ld->topology->tip->height;
+		/* Eventually fuzz it too. */
+		if (pseudorand(10) == 0)
+			locktime -= (u32)pseudorand(100);
 	}
 
 	if (!feerate_per_kw) {