Prevent the UASocketClient from hanging (#316)

* Prevent the UASocketClient from hanging

Added a timeout to the socket connection that prevents the ``UASocketClient`` from hanging on  ``_receive`` in ``_run``.

* introduces new socket_timeout

* added socket_timeout to Client

* fixed small bug

* added timeout handling to SocketWrapper

opcua/client/client.py

@@ -79,7 +79,7 @@ class Client(object):
     which offers the raw OPC-UA services interface.
     """
 
-    def __init__(self, url, timeout=4):
+    def __init__(self, url, timeout=4, socket_timeout=10):
         """
 
         :param url: url of the server.
@@ -101,7 +101,7 @@ class Client(object):
         self.secure_channel_timeout = 3600000 # 1 hour
         self.session_timeout = 3600000 # 1 hour
         self._policy_ids = []
-        self.uaclient = UaClient(timeout)
+        self.uaclient = UaClient(timeout, socket_timeout)
         self.user_certificate = None
         self.user_private_key = None
         self._session_counter = 1

opcua/client/ua_client.py

@@ -18,11 +18,12 @@ class UASocketClient(object):
     handle socket connection and send ua messages
     timeout is the timeout used while waiting for an ua answer from server
     """
-    def __init__(self, timeout=1, security_policy=ua.SecurityPolicy()):
+    def __init__(self, timeout=1, security_policy=ua.SecurityPolicy(), socket_timeout=10):
         self.logger = logging.getLogger(__name__ + ".Socket")
         self._thread = None
         self._lock = Lock()
         self.timeout = timeout
+        self.socket_timeout = socket_timeout
         self._socket = None
         self._do_stop = False
         self.authentication_token = ua.NodeId()
@@ -132,7 +133,7 @@ class UASocketClient(object):
         connect to server socket and start receiving thread
         """
         self.logger.info("opening connection")
-        sock = socket.create_connection((host, port))
+        sock = socket.create_connection((host, port), timeout=self.socket_timeout)
         sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)  # nodelay ncessary to avoid packing in one frame, some servers do not like it
         self._socket = utils.SocketWrapper(sock)
         self.start()
@@ -194,11 +195,12 @@ class UaClient(object):
     uaprotocol_auto.py and uaprotocol_hand.py available under opcua.ua
     """
 
-    def __init__(self, timeout=1):
+    def __init__(self, timeout=1, socket_timeout=10):
         self.logger = logging.getLogger(__name__)
         # _publishcallbacks should be accessed in recv thread only
         self._publishcallbacks = {}
         self._timeout = timeout
+        self._socket_timeout = socket_timeout
         self._uasocket = None
         self._security_policy = ua.SecurityPolicy()
 
@@ -209,7 +211,7 @@ class UaClient(object):
         """
         connect to server socket and start receiving thread
         """
-        self._uasocket = UASocketClient(self._timeout, security_policy=self._security_policy)
+        self._uasocket = UASocketClient(self._timeout, security_policy=self._security_policy, socket_timeout=self._socket_timeout)
         return self._uasocket.connect_socket(host, port)
 
     def disconnect_socket(self):

opcua/common/utils.py

@@ -4,6 +4,7 @@ from concurrent.futures import Future
 import functools
 import threading
 from socket import error as SocketError
+from socket import timeout as SocketTimeout
 
 try:
     # we prefer to use bundles asyncio version, otherwise fallback to trollius
@@ -29,6 +30,10 @@ class SocketClosedException(UaError):
     pass
 
 
+class SocketTimeoutException(UaError):
+    pass
+
+
 class Buffer(object):
 
     """
@@ -102,6 +107,8 @@ class SocketWrapper(object):
         while size > 0:
             try:
                 chunk = self.socket.recv(size)
+            except SocketTimeout as ex:
+                raise SocketTimeoutException("Server socket has timed out")
             except (OSError, SocketError) as ex:
                 raise SocketClosedException("Server socket has closed", ex)
             if not chunk: