initial: ZeroTier-like P2P mesh VPN server with multi-tenant Web UI

internal/middleware/jwt.go

@@ -0,0 +1,58 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/golang-jwt/jwt/v5"
+)
+
+type JWTClaims struct {
+	UserID   uint   `json:"user_id"`
+	Username string `json:"username"`
+	Role     string `json:"role"`
+	jwt.RegisteredClaims
+}
+
+func JWTAuth(secret string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		auth := c.GetHeader("Authorization")
+		if auth == "" {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "missing authorization"})
+			return
+		}
+		parts := strings.SplitN(auth, " ", 2)
+		if len(parts) != 2 || parts[0] != "Bearer" {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid authorization format"})
+			return
+		}
+		claims := &JWTClaims{}
+		token, err := jwt.ParseWithClaims(parts[1], claims, func(t *jwt.Token) (interface{}, error) {
+			return []byte(secret), nil
+		})
+		if err != nil || !token.Valid {
+			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
+			return
+		}
+		c.Set("user_id", claims.UserID)
+		c.Set("username", claims.Username)
+		c.Set("role", claims.Role)
+		c.Next()
+	}
+}
+
+func GenerateToken(secret string, userID uint, username, role string, expireHours int) (string, error) {
+	claims := JWTClaims{
+		UserID:   userID,
+		Username: username,
+		Role:     role,
+		RegisteredClaims: jwt.RegisteredClaims{
+			ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Duration(expireHours) * time.Hour)),
+			IssuedAt:  jwt.NewNumericDate(time.Now()),
+		},
+	}
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+	return token.SignedString([]byte(secret))
+}