auth_utility.go
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package webutility
import (
"errors"
"time"
"crypto/sha256"
"crypto/rand"
"encoding/hex"
"strings"
"github.com/dgrijalva/jwt-go"
)
const OneDay = time.Hour*24
const OneWeek = OneDay*7
const saltSize = 32
const appName = "korisnicki-centar"
const secret = "korisnicki-centar-api"
type TokenClaims struct {
Username string `json:"username"`
Role string `json:"role"`
jwt.StandardClaims
}
type CredentialsStruct struct {
Username string `json:"username"`
Password string `json:"password"`
}
func generateSalt() (salt string, err error) {
rawsalt := make([]byte, saltSize)
_, err = rand.Read(rawsalt)
if err != nil {
return "", err
}
salt = hex.EncodeToString(rawsalt)
return salt, nil
}
func HashString(str string, presalt string) (hash, salt string, err error) {
// chech if message is presalted
if presalt == "" {
salt, err = generateSalt()
if err != nil {
return "", "", err
}
} else {
salt = presalt
}
// convert strings to raw byte slices
rawstr := []byte(str)
rawsalt, err := hex.DecodeString(salt)
if err != nil {
return "", "", err
}
rawdata := make([]byte, len(rawstr) + len(rawsalt))
rawdata = append(rawdata, rawstr...)
rawdata = append(rawdata, rawsalt...)
// hash message + salt
hasher := sha256.New()
hasher.Write(rawdata)
rawhash := hasher.Sum(nil)
hash = hex.EncodeToString(rawhash)
return hash, salt, nil
}
func CreateAPIToken(username, role string) (string, error) {
var apiToken string
var err error
if err != nil {
return "", err
}
claims := TokenClaims{
username,
role,
jwt.StandardClaims{
ExpiresAt: (time.Now().Add(OneWeek)).Unix(),
Issuer: appName,
},
}
jwtToken := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
apiToken, err = jwtToken.SignedString([]byte(secret))
if err != nil {
return "", err
}
return apiToken, nil
}
func RefreshAPIToken(tokenString string) (string, error) {
var newToken string
tokenString = strings.TrimPrefix(tokenString, "Bearer ")
token, err := parseTokenFunc(tokenString)
if err != nil {
return "", err
}
// type assertion
claims, ok := token.Claims.(*TokenClaims)
if !ok || !token.Valid {
return "", errors.New("token is not valid")
}
claims.ExpiresAt = (time.Now().Add(OneWeek)).Unix()
jwtToken := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
newToken, err = jwtToken.SignedString([]byte(secret))
if err != nil {
return "", err
}
return newToken, nil
}
func ParseAPIToken(tokenString string) (*TokenClaims, error) {
if ok := strings.HasPrefix(tokenString, "Bearer"); ok {
tokenString = strings.TrimPrefix(tokenString, "Bearer ")
} else {
return &TokenClaims{}, errors.New("Authorization header is incomplete")
}
token, err := parseTokenFunc(tokenString)
if err != nil {
return &TokenClaims{}, err
}
// type assertion
claims, ok := token.Claims.(*TokenClaims)
if !ok || !token.Valid {
return &TokenClaims{}, errors.New("token is not valid")
}
return claims, nil
}
func parseTokenFunc(tokenString string) (*jwt.Token, error) {
token, err := jwt.ParseWithClaims(tokenString,
&TokenClaims{},
func(token *jwt.Token) (interface{}, error) {
return []byte(secret), nil
},
)
return token, err
}