Map BatchUpdate for complex keys example

[matpuk]

Hello!

I have a bpf map of type BPF_MAP_TYPE_HASH for IPv6 addresses as a key:

struct
{
    __uint(type, BPF_MAP_TYPE_HASH);
    __type(key, struct in6_addr); // IPv6 address
    __type(value, __u8);
    __uint(max_entries, MAX_IP_ENTRIES);
    __uint(map_flags, BPF_F_LOCK);
} ipv6_map SEC(".maps");

Key size is 16bytes long. In Go I declare keys and values as [][]byte and It seems that Map.BatchUpdate() function doesn't like it.
I'm getting error: binary.Append: some values are not fixed-sized in type [][]uint8

Any ideas what is wrong and how to make BatchUpdate() work?

Addresses are loaded from K/V db in the following way:

	keys := make([][]byte, 0)
	values := make([][]byte, 0)

	err := db.IterateKeys(prefix, func(pfx []byte, item *badger.Item) error {
		key := item.KeyCopy(nil)
		keys = append(keys, key[len(pfx):])
		values = append(values, []byte{1})
		return nil
	})
	if err != nil {
		return err
	}

[ti-mo]

Slices are not fixed-size types since their length varies at runtime. Same goes for int and uint since their sizes are architecture-specific. In this case, it sounds like you want to use an array, not a slice: [16]byte. Or, when doing batch operations: [][16]byte.