Golang JWT

JWT.go

package auth

import (
	"errors"
	"time"

	jwt "github.com/dgrijalva/jwt-go"
	"github.com/jinzhu/gorm"
)

const (
	DAYSTOEXPIRE = 10
)

type JWT interface {
	GenerateToken(UUID string) *Token
	ParseToken(tokenString string) (*Token, error)
}

type AuthService struct {
	DB         *gorm.DB
	SigningKey []byte
	Issuer     string
}

type customClaims struct {
	UUID string `json:"id"`
	jwt.StandardClaims
}

type Token struct {
	TokenString string `json:"token"`
	ExpiredAt   int64  `json:"expired_at"`
	IssuedAt    int64  `json:"issued_at;omitempty"`
	Issuer      string `json:"issuer;omitempty"`
	UUID        string `json:"-"`
}

var (
	InvalidTokenError = errors.New("invalid_auth_token")
)

func (auth AuthService) GenerateToken(UUID string) *Token {
	expiredAt := time.Now().Add(time.Hour * 24 * DAYSTOEXPIRE).Unix()

	claims := customClaims{
		UUID,
		jwt.StandardClaims{
			ExpiresAt: expiredAt,
			IssuedAt:  jwt.TimeFunc().Unix(),
			Issuer:    auth.Issuer,
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	ts, _ := token.SignedString(auth.SigningKey)

	return &Token{
		TokenString: ts,
		ExpiredAt:   expiredAt,
	}
}

func (auth AuthService) ParseToken(tokenString string) (*Token, error) {
	token, err := jwt.ParseWithClaims(tokenString, &customClaims{}, func(token *jwt.Token) (interface{}, error) {
		return auth.SigningKey, nil
	})

	if err != nil {
		return nil, InvalidTokenError
	}

	if claims, ok := token.Claims.(*customClaims); ok && token.Valid {
		t := &Token{
			TokenString: tokenString,
			ExpiredAt:   claims.StandardClaims.ExpiresAt,
			IssuedAt:    claims.StandardClaims.IssuedAt,
			Issuer:      claims.StandardClaims.Issuer,
			UUID:        claims.UUID,
		}

		return t, nil
	} else {
		return nil, InvalidTokenError
	}
}