add core/error/util files

pkg/utils/strings.go

@@ -0,0 +1,196 @@
+package utils
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/md5"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"strings"
+	"unicode"
+
+	"golang.org/x/crypto/pbkdf2"
+
+	"github.com/mayswind/lab/pkg/errs"
+)
+
+const (
+	CHARACTERS                = "!#$&()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_abcdefghijklmnopqrstuvwxyz{|}~"
+	NUMBER_AND_LETTERS        = "0123456789abcdefghijklmnopqrstuvwxyz"
+	CHARACTERS_LENGTH         = len(CHARACTERS)
+	NUMBER_AND_LETTERS_LENGTH = len(NUMBER_AND_LETTERS)
+)
+
+func SubString(str string, start int, length int) string {
+	chars := []rune(str)
+	realLength := len(chars)
+	end := 0
+
+	if start < 0 {
+		start = realLength - 1 + start
+	}
+	end = start + length
+
+	if start > end {
+		start, end = end, start
+	}
+
+	if start < 0 {
+		start = 0
+	}
+
+	if start > realLength {
+		start = realLength
+	}
+
+	if end < 0 {
+		end = 0
+	}
+
+	if end > realLength {
+		end = realLength
+	}
+
+	return string(chars[start:end])
+}
+
+func GetFirstLowerCharString(s string) string {
+	if s == "" {
+		return s
+	}
+
+	chars := []rune(s)
+
+	if unicode.IsLower(chars[0]) {
+		return s
+	}
+
+	chars[0] = unicode.ToLower(chars[0])
+	return string(chars)
+}
+
+func GetRandomString(n int) (string, error) {
+	var result = make([]byte, n)
+
+	for i := 0; i < n; i++ {
+		index, err := GetRandomInteger(CHARACTERS_LENGTH)
+
+		if err != nil {
+			return "", err
+		}
+
+		result[i] = CHARACTERS[index]
+	}
+
+	return string(result), nil
+}
+
+func GetRandomNumberOrLetter(n int) (string, error) {
+	var result = make([]byte, n)
+
+	for i := 0; i < n; i++ {
+		index, err := GetRandomInteger(NUMBER_AND_LETTERS_LENGTH)
+
+		if err != nil {
+			return "", err
+		}
+
+		result[i] = NUMBER_AND_LETTERS[index]
+	}
+
+	return string(result), nil
+}
+
+func MD5Encode(data []byte) []byte {
+	m := md5.New()
+	m.Write(data)
+	return m.Sum(nil)
+}
+
+func AESGCMEncrypt(key []byte, plainText []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+
+	if err != nil {
+		return nil, err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+
+	if err != nil {
+		return nil, err
+	}
+
+	nonce := make([]byte, aesgcm.NonceSize())
+
+	if _, err := rand.Read(nonce); err != nil {
+		return nil, err
+	}
+
+	ciphertext := aesgcm.Seal(nil, nonce, plainText, nil)
+	result := append(nonce, ciphertext...)
+
+	return result, nil
+}
+
+func AESGCMDecrypt(key []byte, ciphertext []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+
+	if err != nil {
+		return nil, err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+
+	if err != nil {
+		return nil, err
+	}
+
+	nonceSize := aesgcm.NonceSize()
+
+	if len(ciphertext) - nonceSize <= 0 {
+		return nil, errs.ErrCiphertextInvalid
+	}
+
+	nonce := ciphertext[:nonceSize]
+	ciphertext = ciphertext[nonceSize:]
+
+	plainText, err := aesgcm.Open(nil, nonce, ciphertext, nil)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return plainText, nil
+}
+
+func EncodePassword(password string, salt string) string {
+	encodedPassword := pbkdf2.Key([]byte(password), []byte(salt), 10000, 48, sha256.New) // 256^48 = 64^64
+	return strings.TrimRight(base64.StdEncoding.EncodeToString(encodedPassword), "=")
+}
+
+func EncyptSecret(secret string, key string) (string, error) {
+	encyptedSecret, err := AESGCMEncrypt(MD5Encode([]byte(key)), []byte(secret)) // md5encode make the aes key's length to 16
+
+	if err != nil {
+		return "", err
+	}
+
+	return base64.StdEncoding.EncodeToString(encyptedSecret), nil
+}
+
+func DecryptSecret(encyptedSecret string, key string) (string, error) {
+	encyptedData, err := base64.StdEncoding.DecodeString(encyptedSecret)
+
+	if err != nil {
+		return "", err
+	}
+
+	secret, err := AESGCMDecrypt(MD5Encode([]byte(key)), []byte(encyptedData))
+
+	if err != nil {
+		return "", err
+	}
+
+	return string(secret), nil
+}