all: privilege_allow_ports can be set in frps for ending abuse of ports

conf/frps.ini

@@ -15,6 +15,7 @@ log_max_days = 3
 # if you enable privilege mode, frpc can create a proxy without pre-configure in frps when privilege_token is correct
 privilege_mode = true
 privilege_token = 12345678
+privilege_allow_ports = 2000-3000,3001,3003,4000-50000
 # pool_count in each proxy will change to max_pool_count if they exceed the maximum value
 max_pool_count = 100
 

src/frp/cmd/frps/control.go

@@ -194,6 +194,7 @@ func msgSender(s *server.ProxyServer, c *conn.Conn, msgSendChan chan interface{}
 // if success, ret equals 0, otherwise greater than 0
 func doLogin(req *msg.ControlReq, c *conn.Conn) (ret int64, info string) {
 	ret = 1
+	// check if PrivilegeMode is enabled
 	if req.PrivilegeMode && !server.PrivilegeMode {
 		info = fmt.Sprintf("ProxyName [%s], PrivilegeMode is disabled in frps", req.ProxyName)
 		log.Warn("info")
@@ -247,6 +248,16 @@ func doLogin(req *msg.ControlReq, c *conn.Conn) (ret int64, info string) {
 	if req.Type == consts.NewCtlConn {
 		if req.PrivilegeMode {
 			s = server.NewProxyServerFromCtlMsg(req)
+			// we check listen_port if privilege_allow_ports are set
+			// and PrivilegeMode is enabled
+			if s.Type == "tcp" {
+				_, ok := server.PrivilegeAllowPorts[s.ListenPort]
+				if !ok {
+					info = fmt.Sprintf("ProxyName [%s], remote_port [%d] isn't allowed", req.ProxyName, s.ListenPort)
+					log.Warn(info)
+					return
+				}
+			}
 			err := server.CreateProxy(s)
 			if err != nil {
 				info = fmt.Sprintf("ProxyName [%s], %v", req.ProxyName, err)
@@ -255,12 +266,6 @@ func doLogin(req *msg.ControlReq, c *conn.Conn) (ret int64, info string) {
 			}
 		}
 
-		if s.Status == consts.Working {
-			info = fmt.Sprintf("ProxyName [%s], already in use", req.ProxyName)
-			log.Warn(info)
-			return
-		}
-
 		// check if vhost_port is set
 		if s.Type == "http" && server.VhostHttpMuxer == nil {
 			info = fmt.Sprintf("ProxyName [%s], type [http] not support when vhost_http_port is not set", req.ProxyName)
@@ -285,6 +290,12 @@ func doLogin(req *msg.ControlReq, c *conn.Conn) (ret int64, info string) {
 			s.PoolCount = req.PoolCount
 		}
 
+		if s.Status == consts.Working {
+			info = fmt.Sprintf("ProxyName [%s], already in use", req.ProxyName)
+			log.Warn(info)
+			return
+		}
+
 		// start proxy and listen for user connections, no block
 		err := s.Start(c)
 		if err != nil {

src/frp/models/server/config.go

@@ -42,6 +42,9 @@ var (
 	LogMaxDays     int64  = 3
 	PrivilegeMode  bool   = false
 	PrivilegeToken string = ""
+
+	// if PrivilegeAllowPorts is not nil, tcp proxies which remote port exist in this map can be connected
+	PrivilegeAllowPorts map[int64]struct{}
 	MaxPoolCount        int64 = 100
 	HeartBeatTimeout    int64 = 90
 	UserConnTimeout     int64 = 10
@@ -155,6 +158,43 @@ func loadCommonConf(confFile string) error {
 		} else {
 			return fmt.Errorf("Parse conf error: privilege_token must be set if privilege_mode is enabled")
 		}
+
+		PrivilegeAllowPorts = make(map[int64]struct{})
+		tmpStr, ok = conf.Get("common", "privilege_allow_ports")
+		if ok {
+			// for example: 1000-2000,2001,2002,3000-4000
+			portRanges := strings.Split(tmpStr, ",")
+			for _, portRangeStr := range portRanges {
+				// 1000-2000 or 2001
+				portArray := strings.Split(portRangeStr, "-")
+				// lenght: only 1 or 2 is correct
+				rangeType := len(portArray)
+				if rangeType == 1 {
+					singlePort, err := strconv.ParseInt(portArray[0], 10, 64)
+					if err != nil {
+						return fmt.Errorf("Parse conf error: privilege_allow_ports is incorrect, %v", err)
+					}
+					PrivilegeAllowPorts[singlePort] = struct{}{}
+				} else if rangeType == 2 {
+					min, err := strconv.ParseInt(portArray[0], 10, 64)
+					if err != nil {
+						return fmt.Errorf("Parse conf error: privilege_allow_ports is incorrect, %v", err)
+					}
+					max, err := strconv.ParseInt(portArray[1], 10, 64)
+					if err != nil {
+						return fmt.Errorf("Parse conf error: privilege_allow_ports is incorrect, %v", err)
+					}
+					if max < min {
+						return fmt.Errorf("Parse conf error: privilege_allow_ports range incorrect")
+					}
+					for i := min; i <= max; i++ {
+						PrivilegeAllowPorts[i] = struct{}{}
+					}
+				} else {
+					return fmt.Errorf("Parse conf error: privilege_allow_ports is incorrect")
+				}
+			}
+		}
 	}
 
 	tmpStr, ok = conf.Get("common", "max_pool_count")