Merge pull request #131 from PeterCxy/patch-keepalive

Send ping packets to keep connection alive

butterfly.server.py

@@ -40,6 +40,8 @@ tornado.options.define("unminified", default=False,
 
 tornado.options.define("host", default='localhost', help="Server host")
 tornado.options.define("port", default=57575, type=int, help="Server port")
+tornado.options.define("keepalive_interval", default=30, type=int,
+                        help="Interval between ping packets sent from server to client (in seconds)")
 tornado.options.define("one_shot", default=False,
                        help="Run a one-shot instance. Quit at term close")
 tornado.options.define("shell", help="Shell to execute at login")

butterfly/routes.py

@@ -17,7 +17,9 @@
 
 
 import os
+import struct
 import sys
+import time
 import tornado.options
 import tornado.process
 import tornado.escape
@@ -133,10 +135,15 @@ class TermWebSocket(Route, tornado.websocket.WebSocketHandler):
     # Session history
     history = {}
 
+    # Keepalive timer
+    keepalive_timer = None
+
     def open(self, user, path, session):
+        opts = tornado.options.options
         self.session = session
         self.closed = False
         self.secure_user = None
+        self.keepalive_timer = tornado.ioloop.PeriodicCallback(self.send_ping, opts.keepalive_interval * 1000)
 
         # Prevent cross domain
         if self.request.headers['Origin'] not in (
@@ -155,7 +162,6 @@ class TermWebSocket(Route, tornado.websocket.WebSocketHandler):
         self.set_nodelay(True)
 
         socket = utils.Socket(self.ws_connection.stream.socket)
-        opts = tornado.options.options
 
         if not opts.unsecure:
             user = utils.parse_cert(
@@ -206,6 +212,8 @@ class TermWebSocket(Route, tornado.websocket.WebSocketHandler):
         else:
             self._terminal = terminal
 
+        self.keepalive_timer.start()
+
     @property
     def user_sessions(self):
         """Return the dict session of socket lists"""
@@ -278,6 +286,8 @@ class TermWebSocket(Route, tornado.websocket.WebSocketHandler):
     def on_close(self):
         if self.closed:
             return
+        if self.keepalive_timer != None:
+            self.keepalive_timer.stop()
         self.closed = True
         self.log.info('Websocket closed %r' % self)
         TermWebSocket.sockets.remove(self)
@@ -297,6 +307,15 @@ class TermWebSocket(Route, tornado.websocket.WebSocketHandler):
                     for user, sessions in TermWebSocket.terminals.items()])):
             sys.exit(0)
 
+    def send_ping(self):
+        t = int(time.time())
+        frame = struct.pack('<I', t) # A ping frame based on time
+        self.log.info("Sending ping frame %s" % t)
+        try:
+            self.ping(frame)
+        except tornado.websocket.WebSocketClosedError:
+            self.keepalive_timer.stop()
+
 
 @url(r'/sessions/list.json')
 class SessionsList(Route):