fuzz: add a fuzz target for common/bip32

Signed-off-by: Antoine Poinsot <darosior@protonmail.com>

tests/fuzz/Makefile

@@ -13,6 +13,7 @@ FUZZ_COMMON_OBJS :=					\
 	common/base32.o					\
 	common/base64.o					\
 	common/bech32.o					\
+	common/bip32.o					\
 	common/bigsize.o				\
 	common/json.o					\
 	common/json_stream.o				\

tests/fuzz/fuzz-bip32.c

@@ -0,0 +1,52 @@
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+#include <tests/fuzz/libfuzz.h>
+
+#include <ccan/tal/tal.h>
+#include <common/bip32.h>
+#include <wally_bip32.h>
+
+void init(int *argc, char ***argv)
+{
+}
+
+void run(const uint8_t *data, size_t size)
+{
+	struct ext_key xkey;
+	struct bip32_key_version version;
+	u8 *wire_buff;
+	const uint8_t **xkey_chunks, **ver_chunks, *wire_ptr;
+	size_t wire_max;
+
+	if (size < BIP32_SERIALIZED_LEN)
+		return;
+
+	xkey_chunks = get_chunks(NULL, data, size, BIP32_SERIALIZED_LEN);
+	for (size_t i = 0; i < tal_count(xkey_chunks); i++) {
+		wire_max = tal_bytelen(xkey_chunks[i]);
+		wire_ptr = xkey_chunks[i];
+
+		fromwire_ext_key(&wire_ptr, &wire_max, &xkey);
+		if (wire_ptr) {
+			wire_buff = tal_arr(NULL, uint8_t, BIP32_SERIALIZED_LEN);
+			towire_ext_key(&wire_buff, &xkey);
+			tal_free(wire_buff);
+		}
+	}
+	tal_free(xkey_chunks);
+
+	ver_chunks = get_chunks(NULL, data, size, 4);
+	for (size_t i = 0; i < tal_count(ver_chunks); i++) {
+		wire_max = tal_bytelen(ver_chunks[i]);
+		wire_ptr = ver_chunks[i];
+
+		fromwire_bip32_key_version(&wire_ptr, &wire_max, &version);
+		if (wire_ptr) {
+			wire_buff = tal_arr(NULL, uint8_t, 4);
+			towire_bip32_key_version(&wire_buff, &version);
+			tal_free(wire_buff);
+		}
+	}
+	tal_free(ver_chunks);
+}