fuzz: target for update_fail_htlc

Fuzz the decoding and encoding of update_fail_htlc.

tests/fuzz/fuzz-wire-update_fail_htlc.c

@@ -0,0 +1,43 @@
+#include "config.h"
+#include <ccan/mem/mem.h>
+#include <stdint.h>
+#include <tests/fuzz/libfuzz.h>
+#include <tests/fuzz/wire.h>
+#include <wire/peer_wire.h>
+
+struct update_fail_htlc {
+	struct channel_id channel_id;
+	u64 id;
+	u8 *reason;
+};
+
+static void *encode(const tal_t *ctx, const struct update_fail_htlc *s)
+{
+	return towire_update_fail_htlc(ctx, &s->channel_id, s->id, s->reason);
+}
+
+static struct update_fail_htlc *decode(const tal_t *ctx, const void *p)
+{
+	struct update_fail_htlc *s = tal(ctx, struct update_fail_htlc);
+
+	if (fromwire_update_fail_htlc(s, p, &s->channel_id, &s->id, &s->reason))
+		return s;
+	return tal_free(s);
+}
+
+static bool equal(const struct update_fail_htlc *x,
+		  const struct update_fail_htlc *y)
+{
+	size_t upto_reason = (uintptr_t)&x->reason - (uintptr_t)x;
+	if (memcmp(x, y, upto_reason) != 0)
+		return false;
+
+	return memeq(x->reason, tal_bytelen(x->reason), y->reason,
+		     tal_bytelen(y->reason));
+}
+
+void run(const u8 *data, size_t size)
+{
+	test_decode_encode(data, size, WIRE_UPDATE_FAIL_HTLC,
+			   struct update_fail_htlc);
+}