[telnet_server]1)add TCP_DROP_PREV_CONNECTION

2)fix auth

modules/Telnet_Server/telnet_server.c

@@ -34,6 +34,9 @@
 /* Repeat Login timeout, 1 seconds */
 #define REPEAT_SENSOR_INFO_TIME		configTICK_RATE_HZ*1*1
 
+/* Set option to drop old connection if the new one is accepted */
+#define TCP_DROP_PREV_CONNECTION    1
+
 static portBASE_TYPE FreeRTOS_CLIAuthProcess( const int8_t * const pcCommandInput, int8_t * pcWriteBuffer  );
 static portBASE_TYPE FreeRTOS_ChangePWDProcess( const int8_t * const pcCommandInput, int8_t * pcWriteBuffer  );
 void SensorInfoTimerCallback(TimerHandle_t pxTimer);
@@ -148,6 +151,7 @@ void vBasicSocketsCommandInterpreterTask( void *pvParameters )
     struct sockaddr_in sa_temp;
     socklen_t len;
 #endif
+    static int active_sd = -1;
 
     FD_ZERO(&master_set);
 
@@ -261,17 +265,33 @@ void vBasicSocketsCommandInterpreterTask( void *pvParameters )
 						FD_SET(new_sd, &master_set);
 						if (new_sd > max_sd) {
 							max_sd = new_sd;
+						}
 #ifdef HARDWARE_BT6708
-							lwip_getpeername(new_sd, &sa_temp, &len);
-							flagWhiteListTelnet = white_list_check(sa_temp.sin_addr.s_addr);
+						lwip_getpeername(new_sd, &sa_temp, &len);
+						flagWhiteListTelnet = white_list_check(sa_temp.sin_addr.s_addr);
+#endif
+						recv( new_sd, cInputString, 27, 0 );
+						telnetState = TELNET_AUTH;
+						send( new_sd, pcWelcomeMessage, strlen( ( const char * ) pcWelcomeMessage ), 0 );
+
+						cInputIndex = 0;
+						memset( cInputString, 0x00, cmdMAX_INPUT_SIZE );
+#if TCP_DROP_PREV_CONNECTION
+                    /* Close previous active connection */
+                    if (active_sd != -1 && active_sd != new_sd) {
+                        DBG printf("  Close prev active connection %d\n", active_sd);
+                        close(active_sd);
+                        FD_CLR(active_sd, &master_set);
+                        if (active_sd == max_sd) {
+                            while (FD_ISSET(max_sd, &master_set) == false) {
+                                max_sd -= 1;
+                            }
+                        }
+                    }
+                    /* Mark new connection as active */
+                    active_sd = new_sd;
+                    DBG printf("  New active connection %d\n", active_sd);
 #endif
-							recv( new_sd, cInputString, 27, 0 );
-							telnetState = TELNET_AUTH;
-							send( new_sd, pcWelcomeMessage, strlen( ( const char * ) pcWelcomeMessage ), 0 );
-
-							cInputIndex = 0;
-							memset( cInputString, 0x00, cmdMAX_INPUT_SIZE );
-						}
 
 						/* Loop back up and accept another incoming   */
 						/* connection                                 */