Optional keep alive monitoring for TCP/IP connections

* Since dsmr-parser is listen-only, it will not notice interrupted connections
  and DSMR device restarts. The connection will be reset after an (optional)
  keep-alive interval if no messages were received from the device.

dsmr_parser/__main__.py

@@ -16,8 +16,8 @@ def console():
                         help='alternatively connect using TCP host.')
     parser.add_argument('--port', default=None,
                         help='TCP port to use for connection')
-    parser.add_argument('--version', default='2.2', choices=['2.2', '4'],
-                        help='DSMR version (2.2, 4)')
+    parser.add_argument('--version', default='2.2', choices=['2.2', '4', '5', '5B', '5L'],
+                        help='DSMR version (2.2, 4, 5, 5B, 5L)')
     parser.add_argument('--verbose', '-v', action='count')
 
     args = parser.parse_args()

dsmr_parser/clients/protocol.py

@@ -14,7 +14,7 @@ from dsmr_parser.clients.settings import SERIAL_SETTINGS_V2_2, \
     SERIAL_SETTINGS_V4, SERIAL_SETTINGS_V5
 
 
-def create_dsmr_protocol(dsmr_version, telegram_callback, loop=None):
+def create_dsmr_protocol(dsmr_version, telegram_callback, loop=None, **args):
     """Creates a DSMR asyncio protocol."""
 
     if dsmr_version == '2.2':
@@ -37,7 +37,7 @@ def create_dsmr_protocol(dsmr_version, telegram_callback, loop=None):
                                   dsmr_version)
 
     protocol = partial(DSMRProtocol, loop, TelegramParser(specification),
-                       telegram_callback=telegram_callback)
+                       telegram_callback=telegram_callback, **args)
 
     return protocol, serial_settings
 
@@ -53,12 +53,14 @@ def create_dsmr_reader(port, dsmr_version, telegram_callback, loop=None):
 
 
 def create_tcp_dsmr_reader(host, port, dsmr_version,
-                           telegram_callback, loop=None):
+                           telegram_callback, loop=None,
+                           keep_alive_interval=None):
     """Creates a DSMR asyncio protocol coroutine using TCP connection."""
     if not loop:
         loop = asyncio.get_event_loop()
     protocol, _ = create_dsmr_protocol(
-        dsmr_version, telegram_callback, loop=loop)
+        dsmr_version, telegram_callback, loop=loop,
+        keep_alive_interval=keep_alive_interval)
     conn = loop.create_connection(protocol, host, port)
     return conn
 
@@ -69,7 +71,8 @@ class DSMRProtocol(asyncio.Protocol):
     transport = None
     telegram_callback = None
 
-    def __init__(self, loop, telegram_parser, telegram_callback=None):
+    def __init__(self, loop, telegram_parser,
+                 telegram_callback=None, keep_alive_interval=None):
         """Initialize class."""
         self.loop = loop
         self.log = logging.getLogger(__name__)
@@ -80,21 +83,36 @@ class DSMRProtocol(asyncio.Protocol):
         self.telegram_buffer = TelegramBuffer()
         # keep a lock until the connection is closed
         self._closed = asyncio.Event()
+        self._keep_alive_interval = keep_alive_interval
+        self._active = True
 
     def connection_made(self, transport):
         """Just logging for now."""
         self.transport = transport
         self.log.debug('connected')
+        self._active = False
+        if self._keep_alive_interval:
+            self.loop.call_later(self._keep_alive_interval, self.keep_alive)
 
     def data_received(self, data):
         """Add incoming data to buffer."""
         data = data.decode('ascii')
+        self._active = True
         self.log.debug('received data: %s', data)
         self.telegram_buffer.append(data)
 
         for telegram in self.telegram_buffer.get_all():
             self.handle_telegram(telegram)
 
+    def keep_alive(self):
+        if self._active:
+            self.log.debug('keep-alive checked')
+            self._active = False
+            self.loop.call_later(self._keep_alive_interval, self.keep_alive)
+        else:
+            self.log.debug('keep-alive failed')
+            self.transport.close()
+
     def connection_lost(self, exc):
         """Stop when connection is lost."""
         if exc: