Go Snippets

go-snippets.md

Helpers that are meant to be copied, pasted and modified... not imported.

Cryptography

The secretbox library is intended to minimize the number of ways to screw things up, but using it still requires some setup.

func Seal(data, key []byte) []byte {
	if len(key) != 32 {
		panic("invalid key length")
	}

	var secretKey [32]byte
	var nonce [24]byte

	copy(secretKey[:], key)
	copy(nonce[:], RandBytes(24))

	return secretbox.Seal(nonce[:], []byte(data), &nonce, &secretKey)
}

func Unseal(data, key []byte) ([]byte, error) {
	if len(key) != 32 {
		panic("invalid key length")
	}

	var secretKey [32]byte
	var nonce [24]byte

	copy(secretKey[:], key)

	copy(nonce[:], data[:24])
	decrypted, ok := secretbox.Open(nil, data[24:], &nonce, &secretKey)
	if !ok {
		return nil, errors.New("decryption failure")
	}

	return decrypted, nil
}

Randomness

func RandBytes(len int) []byte {
	d := make([]byte, len)
	if _, err := io.ReadFull(rand.Reader, d); err != nil {
		panic(err)
	}
	return d
}

func RandString(length int) string {
	r := RandBytes((length/4 + 1) * 3)
	encoded := base64.RawURLEncoding.EncodeToString(r)
	return encoded[0:length]
}

Strings

func Dedupe(list []string) []string {
	result := make([]string, 0, len(list))
	m := make(map[string]struct{})

	for _, el := range list {
		if _, ok := m[el]; !ok {
			result = append(result, el)
			m[el] = struct{}{}
		}
	}

	return result
}