feat: add some Radius protocol code (#2351)

* feat: add radius server

* feat: parse org from packet

* feat: add comment

* Update main.go

---------

Co-authored-by: hsluoyz <hsluoyz@qq.com>

radius/server.go

@@ -0,0 +1,67 @@
+// Copyright 2023 The Casdoor Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package radius
+
+import (
+	"log"
+
+	"github.com/casdoor/casdoor/conf"
+	"github.com/casdoor/casdoor/object"
+	"layeh.com/radius"
+	"layeh.com/radius/rfc2865"
+)
+
+// https://support.huawei.com/enterprise/zh/doc/EDOC1000178159/35071f9a#tab_3
+func StartRadiusServer() {
+	server := radius.PacketServer{
+		Addr:         "0.0.0.0:" + conf.GetConfigString("radiusServerPort"),
+		Handler:      radius.HandlerFunc(handlerRadius),
+		SecretSource: radius.StaticSecretSource([]byte(`secret`)),
+	}
+	log.Printf("Starting Radius server on %s", server.Addr)
+	if err := server.ListenAndServe(); err != nil {
+		log.Fatalf("StartRadiusServer() failed, err = %v", err)
+	}
+}
+
+func handlerRadius(w radius.ResponseWriter, r *radius.Request) {
+	switch r.Code {
+	case radius.CodeAccessRequest:
+		handleAccessRequest(w, r)
+	default:
+		log.Printf("radius message, code = %d", r.Code)
+	}
+}
+
+func handleAccessRequest(w radius.ResponseWriter, r *radius.Request) {
+	username := rfc2865.UserName_GetString(r.Packet)
+	password := rfc2865.UserPassword_GetString(r.Packet)
+	organization := parseOrganization(r.Packet)
+	code := radius.CodeAccessAccept
+
+	log.Printf("username=%v, password=%v, code=%v, org=%v", username, password, code, organization)
+	if organization == "" {
+		code = radius.CodeAccessReject
+		w.Write(r.Response(code))
+		return
+	}
+	_, msg := object.CheckUserPassword(organization, username, password, "en")
+	if msg != "" {
+		code = radius.CodeAccessReject
+		w.Write(r.Response(code))
+		return
+	}
+	w.Write(r.Response(code))
+}