From 1abbc3d06a106933b9a00ba5b3388f29391fd25d Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Sat, 29 Jan 2022 14:03:05 +1030
Subject: [PATCH] channeld: simply exit if hsmd vanishes.

We currently die when gossipd vanishes, but our direct connection will
go away.  We then complain if the node is shutting down while we're talking
to hsmd.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 channeld/Makefile     |  1 +
 channeld/channeld.c   | 15 +++++----------
 channeld/channeld.h   | 10 ++++++++++
 channeld/watchtower.c | 15 ++++++---------
 4 files changed, 22 insertions(+), 19 deletions(-)
 create mode 100644 channeld/channeld.h

diff --git a/channeld/Makefile b/channeld/Makefile
index 2c9e89d75..bef41c69a 100644
--- a/channeld/Makefile
+++ b/channeld/Makefile
@@ -4,6 +4,7 @@ CHANNELD_HEADERS :=			\
 	channeld/full_channel_error_names_gen.h	\
 	channeld/channeld_wiregen.h		\
 	channeld/channeld_htlc.h		\
+	channeld/channeld.h			\
 	channeld/commit_tx.h			\
 	channeld/full_channel.h			\
 	channeld/full_channel_error.h		\
diff --git a/channeld/channeld.c b/channeld/channeld.c
index dfc392318..fb90922d2 100644
--- a/channeld/channeld.c
+++ b/channeld/channeld.c
@@ -15,6 +15,7 @@
 #include <ccan/cast/cast.h>
 #include <ccan/mem/mem.h>
 #include <ccan/tal/str/str.h>
+#include <channeld/channeld.h>
 #include <channeld/channeld_wiregen.h>
 #include <channeld/full_channel.h>
 #include <channeld/watchtower.h>
@@ -193,23 +194,17 @@ static void billboard_update(const struct peer *peer)
 	peer_billboard(false, update);
 }
 
-static const u8 *hsm_req(const tal_t *ctx, const u8 *req TAKES)
+const u8 *hsm_req(const tal_t *ctx, const u8 *req TAKES)
 {
 	u8 *msg;
-	int type = fromwire_peektype(req);
 
+	/* hsmd goes away at shutdown.  That's OK. */
 	if (!wire_sync_write(HSM_FD, req))
-		status_failed(STATUS_FAIL_HSM_IO,
-			      "Writing %s to HSM: %s",
-			      hsmd_wire_name(type),
-			      strerror(errno));
+		exit(0);
 
 	msg = wire_sync_read(ctx, HSM_FD);
 	if (!msg)
-		status_failed(STATUS_FAIL_HSM_IO,
-			      "Reading resp to %s: %s",
-			      hsmd_wire_name(type),
-			      strerror(errno));
+		exit(0);
 
 	return msg;
 }
diff --git a/channeld/channeld.h b/channeld/channeld.h
new file mode 100644
index 000000000..a2b26b082
--- /dev/null
+++ b/channeld/channeld.h
@@ -0,0 +1,10 @@
+#ifndef LIGHTNING_CHANNELD_CHANNELD_H
+#define LIGHTNING_CHANNELD_CHANNELD_H
+#include "config.h"
+#include <ccan/short_types/short_types.h>
+#include <ccan/take/take.h>
+#include <ccan/tal/tal.h>
+
+const u8 *hsm_req(const tal_t *ctx, const u8 *req TAKES);
+
+#endif /* LIGHTNING_CHANNELD_CHANNELD_H */
diff --git a/channeld/watchtower.c b/channeld/watchtower.c
index 20d273d65..e91dc4f89 100644
--- a/channeld/watchtower.c
+++ b/channeld/watchtower.c
@@ -1,6 +1,7 @@
 #include "config.h"
 #include <bitcoin/feerate.h>
 #include <bitcoin/script.h>
+#include <channeld/channeld.h>
 #include <channeld/watchtower.h>
 #include <common/features.h>
 #include <common/htlc_tx.h>
@@ -26,7 +27,7 @@ penalty_tx_create(const tal_t *ctx,
 	struct bitcoin_tx *tx;
 	struct keyset keyset;
 	size_t weight;
-	u8 *msg;
+	const u8 *msg;
 	struct amount_sat fee, min_out, amt;
 	struct bitcoin_signature sig;
 	u32 locktime = 0;
@@ -105,16 +106,12 @@ penalty_tx_create(const tal_t *ctx,
 	bitcoin_tx_finalize(tx);
 
 	u8 *hsm_sign_msg =
-	    towire_hsmd_sign_penalty_to_us(ctx, &remote_per_commitment_secret,
+	    towire_hsmd_sign_penalty_to_us(tmpctx, &remote_per_commitment_secret,
 					  tx, wscript);
 
-	if (!wire_sync_write(hsm_fd, take(hsm_sign_msg)))
-		status_failed(STATUS_FAIL_INTERNAL_ERROR,
-			      "Writing sign request to hsm");
-
-	msg = wire_sync_read(tmpctx, hsm_fd);
-	if (!msg || !fromwire_hsmd_sign_tx_reply(msg, &sig))
-		status_failed(STATUS_FAIL_INTERNAL_ERROR,
+	msg = hsm_req(tmpctx, hsm_sign_msg);
+	if (!fromwire_hsmd_sign_tx_reply(msg, &sig))
+		status_failed(STATUS_FAIL_HSM_IO,
 			      "Reading sign_tx_reply: %s", tal_hex(tmpctx, msg));
 
 	witness = bitcoin_witness_sig_and_element(tx, &sig, &ONE, sizeof(ONE),