From 95dfc551f7eaaf6e8ebdefce1b733951354ac40d Mon Sep 17 00:00:00 2001
From: Vidhu Kant Sharma <vidhukant@vidhukant.com>
Date: Sun, 3 Sep 2023 15:00:03 +0530
Subject: added JWT authorization middleware

---
 auth/middleware.go | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 auth/middleware.go

(limited to 'auth/middleware.go')

diff --git a/auth/middleware.go b/auth/middleware.go
new file mode 100644
index 0000000..299a7be
--- /dev/null
+++ b/auth/middleware.go
@@ -0,0 +1,77 @@
+/* openbills - Server for web based Libre Billing Software
+ * Copyright (C) 2023  Vidhu Kant Sharma <vidhukant@vidhukant.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package auth
+
+import (
+	"vidhukant.com/openbills/errors"
+	"github.com/gin-gonic/gin"
+	"github.com/golang-jwt/jwt/v5"
+	"strings"
+	"time"
+)
+
+func getBearerToken(header []string) (string, error) {
+	if len(header) > 0 {
+		s := strings.Split(header[0], "Bearer ")
+		if len(s) == 2 {
+			return s[1], nil
+		} else {
+			return "", errors.ErrInvalidAuthHeader
+		}
+	} else {
+		return "", errors.ErrInvalidAuthHeader
+	}
+}
+
+func Authorize() gin.HandlerFunc {
+	return func(ctx *gin.Context) {
+		bearerToken, err := getBearerToken(ctx.Request.Header["Authorization"])
+		if err != nil {
+			ctx.Error(err)
+			ctx.Abort()
+			return
+		}
+
+		tk, err := jwt.ParseWithClaims(bearerToken, &AuthClaims{}, func (token *jwt.Token) (interface{}, error) {
+			return []byte(AUTH_KEY), nil
+		})
+
+		claims, ok := tk.Claims.(*AuthClaims)
+		if !ok {
+			ctx.Error(errors.ErrInvalidAuthHeader)
+			ctx.Abort()
+			return
+		}
+
+		if !tk.Valid {
+			eat := claims.ExpiresAt.Unix()
+			if eat != 0 && eat < time.Now().Unix() {
+				ctx.Error(errors.ErrSessionExpired)
+			} else {
+				ctx.Error(errors.ErrUnauthorized)
+			}
+
+			ctx.Abort()
+			return
+		}
+
+		ctx.Set("UserID", claims.UserID)
+
+		ctx.Next()
+	}
+}
-- 
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