fuzz: target for update_blockheight

Fuzz the decoding and encoding of update_blockheight.

tests/fuzz/fuzz-wire-update_blockheight.c

@@ -0,0 +1,37 @@
+#include "config.h"
+#include <common/channel_id.h>
+#include <tests/fuzz/libfuzz.h>
+#include <tests/fuzz/wire.h>
+#include <wire/peer_wire.h>
+
+struct update_blockheight {
+	struct channel_id channel_id;
+	u32 blockheight;
+};
+
+static void *encode(const tal_t *ctx, const struct update_blockheight *s)
+{
+	return towire_update_blockheight(ctx, &s->channel_id, s->blockheight);
+}
+
+static struct update_blockheight *decode(const tal_t *ctx, const void *p)
+{
+	struct update_blockheight *s = tal(ctx, struct update_blockheight);
+
+	if (fromwire_update_blockheight(p, &s->channel_id, &s->blockheight))
+		return s;
+	return tal_free(s);
+}
+
+static bool equal(const struct update_blockheight *x,
+		  const struct update_blockheight *y)
+{
+	return channel_id_eq(&x->channel_id, &y->channel_id) &&
+	       x->blockheight == y->blockheight;
+}
+
+void run(const u8 *data, size_t size)
+{
+	test_decode_encode(data, size, WIRE_UPDATE_BLOCKHEIGHT,
+			   struct update_blockheight);
+}