openvpn-manager/backend/internal/middleware/auth.go

package middleware

import (
	"net/http"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
)

type Claims struct {
	Username string `json:"username"`
	Role     string `json:"role"`
	jwt.RegisteredClaims
}

func IssueToken(secret, username, role string, ttl time.Duration) (string, error) {
	c := Claims{
		Username: username,
		Role:     role,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(ttl)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}
	t := jwt.NewWithClaims(jwt.SigningMethodHS256, c)
	return t.SignedString([]byte(secret))
}

func JWTAuth(secret string) gin.HandlerFunc {
	return func(c *gin.Context) {
		h := c.GetHeader("Authorization")
		if h == "" {
			h = c.Query("token")
		}
		const prefix = "Bearer "
		if strings.HasPrefix(h, prefix) {
			h = strings.TrimPrefix(h, prefix)
		}
		if h == "" {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "missing token"})
			return
		}
		claims := &Claims{}
		_, err := jwt.ParseWithClaims(h, claims, func(t *jwt.Token) (interface{}, error) {
			return []byte(secret), nil
		})
		if err != nil {
			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
			return
		}
		c.Set("user", claims.Username)
		c.Set("role", claims.Role)
		c.Next()
	}
}