Add WebSocket keepalive ping support with configurable interval

daphne/cli.py

@@ -54,6 +54,12 @@ class CommandLineInterface(object):
             help='How long to wait for worker server before timing out HTTP connections',
             default=120,
         )
+        self.parser.add_argument(
+            '--ping-interval',
+            type=int,
+            help='The number of seconds a WebSocket must be idle before a keepalive ping is sent',
+            default=20,
+        )
         self.parser.add_argument(
             'channel_layer',
             help='The ASGI channel layer instance to use as path.to.module:instance.path',
@@ -100,4 +106,5 @@ class CommandLineInterface(object):
             port=args.port,
             unix_socket=args.unix_socket,
             http_timeout=args.http_timeout,
+            ping_interval=args.ping_interval,
         ).run()

daphne/http_protocol.py

@@ -219,12 +219,13 @@ class HTTPFactory(http.HTTPFactory):
 
     protocol = HTTPProtocol
 
-    def __init__(self, channel_layer, action_logger=None, timeout=120, websocket_timeout=86400):
+    def __init__(self, channel_layer, action_logger=None, timeout=120, websocket_timeout=86400, ping_interval=20):
         http.HTTPFactory.__init__(self)
         self.channel_layer = channel_layer
         self.action_logger = action_logger
         self.timeout = timeout
         self.websocket_timeout = websocket_timeout
+        self.ping_interval = ping_interval
         # We track all sub-protocols for response channel mapping
         self.reply_protocols = {}
         # Make a factory for WebSocket protocols
@@ -264,6 +265,11 @@ class HTTPFactory(http.HTTPFactory):
             # Web timeout checking
             if isinstance(protocol, WebRequest) and protocol.duration() > self.timeout:
                 protocol.basic_error(503, b"Service Unavailable", "Worker server failed to respond within time limit.")
-            # WebSocket timeout checking
-            elif isinstance(protocol, WebSocketProtocol) and protocol.duration() > self.websocket_timeout:
+            # WebSocket timeout checking and keepalive ping sending
+            elif isinstance(protocol, WebSocketProtocol):
+                # Timeout check
+                if protocol.duration() > self.websocket_timeout:
                     protocol.serverClose()
+                # Ping check
+                else:
+                    protocol.check_ping()

daphne/server.py

@@ -18,6 +18,7 @@ class Server(object):
         action_logger=None,
         http_timeout=120,
         websocket_timeout=None,
+        ping_interval=20,
     ):
         self.channel_layer = channel_layer
         self.host = host
@@ -26,6 +27,7 @@ class Server(object):
         self.signal_handlers = signal_handlers
         self.action_logger = action_logger
         self.http_timeout = http_timeout
+        self.ping_interval = ping_interval
         # If they did not provide a websocket timeout, default it to the
         # channel layer's group_expiry value if present, or one day if not.
         self.websocket_timeout = websocket_timeout or getattr(channel_layer, "group_expiry", 86400)
@@ -36,6 +38,7 @@ class Server(object):
             self.action_logger,
             timeout=self.http_timeout,
             websocket_timeout=self.websocket_timeout,
+            ping_interval=self.ping_interval,
         )
         if self.unix_socket:
             reactor.listenUNIX(self.unix_socket, self.factory)
@@ -68,7 +71,8 @@ class Server(object):
 
     def timeout_checker(self):
         """
-        Called periodically to enforce timeout rules on all connections
+        Called periodically to enforce timeout rules on all connections.
+        Also checks pings at the same time.
         """
         self.factory.check_timeouts()
         reactor.callLater(2, self.timeout_checker)

daphne/ws_protocol.py

@@ -24,6 +24,7 @@ class WebSocketProtocol(WebSocketServerProtocol):
         self.request = request
         self.packets_received = 0
         self.socket_opened = time.time()
+        self.last_data = time.time()
         try:
             # Sanitize and decode headers
             clean_headers = {}
@@ -68,6 +69,7 @@ class WebSocketProtocol(WebSocketServerProtocol):
     def onMessage(self, payload, isBinary):
         logger.debug("WebSocket incoming packet on %s", self.reply_channel)
         self.packets_received += 1
+        self.last_data = time.time()
         if isBinary:
             self.channel_layer.send("websocket.receive", {
                 "reply_channel": self.reply_channel,
@@ -87,6 +89,7 @@ class WebSocketProtocol(WebSocketServerProtocol):
         """
         Server-side channel message to send a message.
         """
+        self.last_data = time.time()
         logger.debug("Sent WebSocket packet to client for %s", self.reply_channel)
         if binary:
             self.sendMessage(content, binary)
@@ -121,6 +124,14 @@ class WebSocketProtocol(WebSocketServerProtocol):
         """
         return time.time() - self.socket_opened
 
+    def check_ping(self):
+        """
+        Checks to see if we should send a keepalive ping.
+        """
+        if (time.time() - self.last_data) > self.main_factory.ping_interval:
+            self.sendPing()
+            self.last_data = time.time()
+
 
 class WebSocketFactory(WebSocketServerFactory):
     """