signet-backend/auth/auth.go

package auth

import (
	"fmt"
	"net/http"
	"strings"

	"github.com/golang-jwt/jwt/v4"
	"github.com/spf13/viper"
)

type Claims struct {
	ID         uint   `json:"id"`
	Username   string `json:"username"`
	Privileges uint   `json:"privileges"`
	jwt.RegisteredClaims
}

func GetUserClaims(r *http.Request) (rights *Claims, err error) {
	var token *jwt.Token
	authHeader := r.Header.Get("Authorization")
	if authHeader == "" {
		return nil, nil
	}

	claims := &Claims{}

	_, t, _ := strings.Cut(r.Header.Get("Authorization"), "Bearer ")
	token, _ = jwt.ParseWithClaims(t, claims, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}

		return []byte(viper.GetString("app.secretKey")), nil
	})
	if !token.Valid {
		return nil, nil
	}
	return claims, nil
}