From e616b4fff73372694f621afba6a99d5c7d93da86 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Wed, 30 Mar 2022 14:13:12 +1030
Subject: [PATCH] lightningd: add extra debugging for weird onchain htlc
 interactions.

This doesn't actually fix anything, but may shed more clues if it
happens again.

The broken() logs are overzealous, see next patch.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 lightningd/peer_htlcs.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/lightningd/peer_htlcs.c b/lightningd/peer_htlcs.c
index 7a434bbd3..b17eadf0e 100644
--- a/lightningd/peer_htlcs.c
+++ b/lightningd/peer_htlcs.c
@@ -1418,13 +1418,23 @@ void onchain_failed_our_htlc(const struct channel *channel,
 	struct lightningd *ld = channel->peer->ld;
 	struct htlc_out *hout;
 
+	log_debug(channel->log, "onchain_failed_our_htlc");
 	hout = find_htlc_out(&ld->htlcs_out, channel, htlc->id);
-	if (!hout)
+	if (!hout) {
+		log_broken(channel->log, "HTLC id %"PRIu64" not found!",
+			   htlc->id);
 		return;
+	}
 
 	/* Don't fail twice (or if already succeeded)! */
-	if (hout->failonion || hout->failmsg || hout->preimage)
+	if (hout->failonion || hout->failmsg || hout->preimage) {
+		log_debug(channel->log, "HTLC id %"PRIu64" failonion = %p, failmsg = %p, preimage = %p",
+			  htlc->id,
+			  hout->failonion,
+			  hout->failmsg,
+			  hout->preimage);
 		return;
+	}
 
 	hout->failmsg = towire_permanent_channel_failure(hout);
 
@@ -1441,6 +1451,8 @@ void onchain_failed_our_htlc(const struct channel *channel,
 			   hout->failmsg, &we_filled);
 
 	if (hout->am_origin) {
+		log_debug(channel->log, "HTLC id %"PRIu64" am origin",
+			  htlc->id);
 		assert(why != NULL);
 		char *localfail = tal_fmt(channel, "%s: %s",
 					  onion_wire_name(WIRE_PERMANENT_CHANNEL_FAILURE),
@@ -1448,6 +1460,8 @@ void onchain_failed_our_htlc(const struct channel *channel,
 		payment_failed(ld, hout, localfail);
 		tal_free(localfail);
 	} else if (hout->in) {
+		log_debug(channel->log, "HTLC id %"PRIu64" has incoming",
+			  htlc->id);
 		local_fail_in_htlc(hout->in,
 				   take(towire_permanent_channel_failure(NULL)));
 		wallet_forwarded_payment_add(hout->key.channel->peer->ld->wallet,
@@ -1456,7 +1470,9 @@ void onchain_failed_our_htlc(const struct channel *channel,
 					 hout->failmsg
 					 ? fromwire_peektype(hout->failmsg)
 					 : 0);
-	}
+	} else
+		log_broken(channel->log, "HTLC id %"PRIu64" is from nowhere?",
+			   htlc->id);
 }
 
 static void remove_htlc_in(struct channel *channel, struct htlc_in *hin)