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package auth
import (
"fmt"
"net/http"
"os"
"strings"
"time"
"github.com/golang-jwt/jwt/v5"
"github.com/joho/godotenv"
)
func init() {
godotenv.Load()
}
var jwtSecret = []byte(os.Getenv("JWT_SECRET"))
const algo = "HS256"
func GenerateJWT(userID string, duration time.Duration) (string, error) {
claims := jwt.MapClaims{
"sub": userID,
"exp": time.Now().Add(duration).Unix(),
"iat": time.Now().Unix(),
}
token := jwt.NewWithClaims(jwt.GetSigningMethod(algo), claims)
signedToken, err := token.SignedString(jwtSecret)
if err != nil {
return "", fmt.Errorf("failed to sign token: %w", err)
}
return signedToken, nil
}
func validateJWT(tokenString string, expectedAlg string) (jwt.MapClaims, error) {
token, err := jwt.Parse(tokenString, func(token *jwt.Token) (any, error) {
if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
return nil, fmt.Errorf("invalid token: %v", token.Header["alg"])
}
if token.Method != jwt.GetSigningMethod(expectedAlg) {
return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
}
return jwtSecret, nil
})
if err != nil {
return nil, err
}
claims, ok := token.Claims.(jwt.MapClaims)
if !ok || !token.Valid {
return nil, fmt.Errorf("JWT validation failed: invalid claims")
}
if exp, ok := claims["exp"].(float64); ok {
if int64(exp) < time.Now().Unix() {
return nil, fmt.Errorf("JWT validation failed: token expired")
}
}
return claims, nil
}
func VerifyRequest(r *http.Request) (jwt.MapClaims, error) {
authHeader := r.Header.Get("Authorization")
if authHeader == "" {
return nil, fmt.Errorf("Missing Authorization header in request")
}
// expected: "Bearer <token>"
authSplit := strings.Split(authHeader, " ")
if len(authSplit) != 2 || authSplit[0] != "Bearer" {
return nil, fmt.Errorf("Malformed Authorization header in request")
}
token := authSplit[1]
claims, err := validateJWT(token, algo)
if err != nil {
fmt.Printf("JWT error: %v for token: %s\n", err, token)
return nil, err
}
return claims, nil
}
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