Client.connect_and_find_servers() - Code Metrics - Inspection of "Use generic try/catch instead of using concurrent...." - FreeOpcUa/python-opcua - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( 96bac7...bd9702 )

by Olivier

created 2018-02-15 09:11 UTC

Client.connect_and_find_servers() A

↳ Parent: Project

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	1
CRAP Score	1.7023

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	1
c	1
b	0
f	0
dl	0
loc	13
ccs	1
cts	9
cp	0.1111
crap	1.7023
rs	9.4285

from __future__ import division  # support for python2
from threading import Thread, Condition
import logging
try:
    from urllib.parse import urlparse
except ImportError:  # support for python2
    from urlparse import urlparse

from opcua import ua
from opcua.client.ua_client import UaClient
from opcua.common.xmlimporter import XmlImporter
from opcua.common.xmlexporter import XmlExporter
from opcua.common.node import Node
from opcua.common.manage_nodes import delete_nodes
from opcua.common.subscription import Subscription
from opcua.common import utils
from opcua.crypto import security_policies
from opcua.common.shortcuts import Shortcuts
from opcua.common.structures import load_type_definitions
use_crypto = True
try:
    from opcua.crypto import uacrypto
except ImportError:
    logging.getLogger(__name__).warning("cryptography is not installed, use of crypto disabled")
    use_crypto = False


class KeepAlive(Thread):

    """
    Used by Client to keep the session open.
    OPCUA defines timeout both for sessions and secure channel
    """

    def __init__(self, client, timeout):
        """
        :param session_timeout: Timeout to re-new the session
            in milliseconds.
        """
        Thread.__init__(self)
        self.logger = logging.getLogger(__name__)

        self.client = client
        self._dostop = False
        self._cond = Condition()
        self.timeout = timeout

        # some server support no timeout, but we do not trust them
        if self.timeout == 0:
            self.timeout = 3600000 # 1 hour

    def run(self):
        self.logger.debug("starting keepalive thread with period of %s milliseconds", self.timeout)
        server_state = self.client.get_node(ua.FourByteNodeId(ua.ObjectIds.Server_ServerStatus_State))
        while not self._dostop:
            with self._cond:
                self._cond.wait(self.timeout / 1000)
            if self._dostop:
                break
            self.logger.debug("renewing channel")
            self.client.open_secure_channel(renew=True)
            val = server_state.get_value()
            self.logger.debug("server state is: %s ", val)
        self.logger.debug("keepalive thread has stopped")

    def stop(self):
        self.logger.debug("stoping keepalive thread")
        self._dostop = True
        with self._cond:
            self._cond.notify_all()


class Client(object):

    """
    High level client to connect to an OPC-UA server.

    This class makes it easy to connect and browse address space.
    It attemps to expose as much functionality as possible
    but if you want more flexibility it is possible and adviced to
    use UaClient object, available as self.uaclient
    which offers the raw OPC-UA services interface.
    """

    def __init__(self, url, timeout=4):
        """

        :param url: url of the server.
            if you are unsure of url, write at least hostname
            and port and call get_endpoints

        :param timeout:
            Each request sent to the server expects an answer within this
            time. The timeout is specified in seconds.
        """
        self.logger = logging.getLogger(__name__)
        self.server_url = urlparse(url)
        #take initial username and password from the url
        self._username = self.server_url.username
        self._password = self.server_url.password
        self.name = "Pure Python Client"
        self.description = self.name
        self.application_uri = "urn:freeopcua:client"
        self.product_uri = "urn:freeopcua.github.no:client"
        self.security_policy = ua.SecurityPolicy()
        self.secure_channel_id = None
        self.secure_channel_timeout = 3600000 # 1 hour
        self.session_timeout = 3600000 # 1 hour
        self._policy_ids = []
        self.uaclient = UaClient(timeout)
        self.user_certificate = None
        self.user_private_key = None
        self._server_nonce = None
        self._session_counter = 1
        self.keepalive = None
        self.nodes = Shortcuts(self.uaclient)
        self.max_messagesize = 0 # No limits
        self.max_chunkcount = 0 # No limits


    def __enter__(self):
        self.connect()
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.disconnect()

    @staticmethod
    def find_endpoint(endpoints, security_mode, policy_uri):
        """
        Find endpoint with required security mode and policy URI
        """
        for ep in endpoints:
            if (ep.EndpointUrl.startswith(ua.OPC_TCP_SCHEME) and
                    ep.SecurityMode == security_mode and
                    ep.SecurityPolicyUri == policy_uri):
                return ep
        raise ua.UaError("No matching endpoints: {0}, {1}".format(security_mode, policy_uri))

    def set_user(self, username):
        """
        Set user name for the connection.
        initial user from the URL will be overwritten
        """
        self._username = username

    def set_password(self, pwd):
        """
        Set user password for the connection.
        initial password from the URL will be overwritten
        """
        self._password = pwd   

    def set_security_string(self, string):
        """
        Set SecureConnection mode. String format:
        Policy,Mode,certificate,private_key[,server_private_key]
        where Policy is Basic128Rsa15 or Basic256,
            Mode is Sign or SignAndEncrypt
            certificate, private_key and server_private_key are
                paths to .pem or .der files
        Call this before connect()
        """
        if not string:
            return
        parts = string.split(',')
        if len(parts) < 4:
            raise ua.UaError('Wrong format: `{0}`, expected at least 4 comma-separated values'.format(string))
        policy_class = getattr(security_policies, 'SecurityPolicy' + parts[0])
        mode = getattr(ua.MessageSecurityMode, parts[1])
        return self.set_security(policy_class, parts[2], parts[3],
                                 parts[4] if len(parts) >= 5 else None, mode)

    def set_security(self, policy, certificate_path, private_key_path,
                     server_certificate_path=None,
                     mode=ua.MessageSecurityMode.SignAndEncrypt):
        """
        Set SecureConnection mode.
        Call this before connect()
        """
        if server_certificate_path is None:
            # load certificate from server's list of endpoints
            endpoints = self.connect_and_get_server_endpoints()
            endpoint = Client.find_endpoint(endpoints, mode, policy.URI)
            server_cert = uacrypto.x509_from_der(endpoint.ServerCertificate)
        else:
            server_cert = uacrypto.load_certificate(server_certificate_path)
        cert = uacrypto.load_certificate(certificate_path)
        pk = uacrypto.load_private_key(private_key_path)
        self.security_policy = policy(server_cert, cert, pk, mode)
        self.uaclient.set_security(self.security_policy)

    def load_client_certificate(self, path):
        """
        load our certificate from file, either pem or der
        """
        self.user_certificate = uacrypto.load_certificate(path)

    def load_private_key(self, path):
        """
        Load user private key. This is used for authenticating using certificate
        """
        self.user_private_key = uacrypto.load_private_key(path)

    def connect_and_get_server_endpoints(self):
        """
        Connect, ask server for endpoints, and disconnect
        """
        self.connect_socket()
        try:
            self.send_hello()
            self.open_secure_channel()
            endpoints = self.get_endpoints()
            self.close_secure_channel()
        finally:
            self.disconnect_socket()
        return endpoints

    def connect_and_find_servers(self):
        """
        Connect, ask server for a list of known servers, and disconnect
        """
        self.connect_socket()
        try:
            self.send_hello()
            self.open_secure_channel()  # spec says it should not be necessary to open channel
            servers = self.find_servers()
            self.close_secure_channel()
        finally:
            self.disconnect_socket()
        return servers

    def connect_and_find_servers_on_network(self):
        """
        Connect, ask server for a list of known servers on network, and disconnect
        """
        self.connect_socket()
        try:
            self.send_hello()
            self.open_secure_channel()
            servers = self.find_servers_on_network()
            self.close_secure_channel()
        finally:
            self.disconnect_socket()
        return servers

    def connect(self):
        """
        High level method
        Connect, create and activate session
        """
        self.connect_socket()
        try:
            self.send_hello()
            self.open_secure_channel()
            self.create_session()
        except:
            self.disconnect_socket() # clean up open socket
            raise
        self.activate_session(username=self._username, password=self._password, certificate=self.user_certificate)

    def disconnect(self):
        """
        High level method
        Close session, secure channel and socket
        """
        try:
            self.close_session()
            self.close_secure_channel()
        finally:
            self.disconnect_socket()

    def connect_socket(self):
        """
        connect to socket defined in url
        """
        self.uaclient.connect_socket(self.server_url.hostname, self.server_url.port)

    def disconnect_socket(self):
        self.uaclient.disconnect_socket()

    def send_hello(self):
        """
        Send OPC-UA hello to server
        """
        ack = self.uaclient.send_hello(self.server_url.geturl(), self.max_messagesize, self.max_chunkcount)
        # FIXME check ack

    def open_secure_channel(self, renew=False):
        """
        Open secure channel, if renew is True, renew channel
        """
        params = ua.OpenSecureChannelParameters()
        params.ClientProtocolVersion = 0
        params.RequestType = ua.SecurityTokenRequestType.Issue
        if renew:
            params.RequestType = ua.SecurityTokenRequestType.Renew
        params.SecurityMode = self.security_policy.Mode
        params.RequestedLifetime = self.secure_channel_timeout
        nonce = utils.create_nonce(self.security_policy.symmetric_key_size)   # length should be equal to the length of key of symmetric encryption
        params.ClientNonce = nonce	# this nonce is used to create a symmetric key
        result = self.uaclient.open_secure_channel(params)
        self.security_policy.make_symmetric_key(nonce, result.ServerNonce)
        self.secure_channel_timeout = result.SecurityToken.RevisedLifetime

    def close_secure_channel(self):
        return self.uaclient.close_secure_channel()

    def get_endpoints(self):
        params = ua.GetEndpointsParameters()
        params.EndpointUrl = self.server_url.geturl()
        return self.uaclient.get_endpoints(params)

    def register_server(self, server, discovery_configuration=None):
        """
        register a server to discovery server
        if discovery_configuration is provided, the newer register_server2 service call is used
        """
        serv = ua.RegisteredServer()
        serv.ServerUri = server.application_uri
        serv.ProductUri = server.product_uri
        serv.DiscoveryUrls = [server.endpoint.geturl()]
        serv.ServerType = server.application_type
        serv.ServerNames = [ua.LocalizedText(server.name)]
        serv.IsOnline = True
        if discovery_configuration:
            params = ua.RegisterServer2Parameters()
            params.Server = serv
            params.DiscoveryConfiguration = discovery_configuration
            return self.uaclient.register_server2(params)
        else:
            return self.uaclient.register_server(serv)

    def find_servers(self, uris=None):
        """
        send a FindServer request to the server. The answer should be a list of
        servers the server knows about
        A list of uris can be provided, only server having matching uris will be returned
        """
        if uris is None:
            uris = []
        params = ua.FindServersParameters()
        params.EndpointUrl = self.server_url.geturl()
        params.ServerUris = uris
        return self.uaclient.find_servers(params)

    def find_servers_on_network(self):
        params = ua.FindServersOnNetworkParameters()
        return self.uaclient.find_servers_on_network(params)

    def create_session(self):
        """
        send a CreateSessionRequest to server with reasonable parameters.
        If you want o modify settings look at code of this methods
        and make your own
        """
        desc = ua.ApplicationDescription()
        desc.ApplicationUri = self.application_uri
        desc.ProductUri = self.product_uri
        desc.ApplicationName = ua.LocalizedText(self.name)
        desc.ApplicationType = ua.ApplicationType.Client

        params = ua.CreateSessionParameters()
        nonce = utils.create_nonce(32)  # at least 32 random bytes for server to prove possession of private key (specs part 4, 5.6.2.2)
        params.ClientNonce = nonce
        params.ClientCertificate = self.security_policy.client_certificate
        params.ClientDescription = desc
        params.EndpointUrl = self.server_url.geturl()
        params.SessionName = self.description + " Session" + str(self._session_counter)
        params.RequestedSessionTimeout = 3600000
        params.MaxResponseMessageSize = 0  # means no max size
        response = self.uaclient.create_session(params)
        if self.security_policy.client_certificate is None:
            data = nonce
        else:
            data = self.security_policy.client_certificate + nonce
        self.security_policy.asymmetric_cryptography.verify(data, response.ServerSignature.Signature)
        self._server_nonce = response.ServerNonce
        if not self.security_policy.server_certificate:
            self.security_policy.server_certificate = response.ServerCertificate
        elif self.security_policy.server_certificate != response.ServerCertificate:
            raise ua.UaError("Server certificate mismatch")
        # remember PolicyId's: we will use them in activate_session()
        ep = Client.find_endpoint(response.ServerEndpoints, self.security_policy.Mode, self.security_policy.URI)
        self._policy_ids = ep.UserIdentityTokens
        self.session_timeout = response.RevisedSessionTimeout
        self.keepalive = KeepAlive(self, min(self.session_timeout, self.secure_channel_timeout) * 0.7)  # 0.7 is from spec
        self.keepalive.start()
        return response

    def server_policy_id(self, token_type, default):
        """
        Find PolicyId of server's UserTokenPolicy by token_type.
        Return default if there's no matching UserTokenPolicy.
        """
        for policy in self._policy_ids:
            if policy.TokenType == token_type:
                return policy.PolicyId
        return default

    def server_policy_uri(self, token_type):
        """
        Find SecurityPolicyUri of server's UserTokenPolicy by token_type.
        If SecurityPolicyUri is empty, use default SecurityPolicyUri
        of the endpoint
        """
        for policy in self._policy_ids:
            if policy.TokenType == token_type:
                if policy.SecurityPolicyUri:
                    return policy.SecurityPolicyUri
                else:   # empty URI means "use this endpoint's policy URI"
                    return self.security_policy.URI
        return self.security_policy.URI

    def activate_session(self, username=None, password=None, certificate=None):
        """
        Activate session using either username and password or private_key
        """
        params = ua.ActivateSessionParameters()
        challenge = b""
        if self.security_policy.server_certificate is not None:
            challenge += self.security_policy.server_certificate
        if self._server_nonce is not None:
            challenge += self._server_nonce
        params.ClientSignature.Algorithm = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"
        params.ClientSignature.Signature = self.security_policy.asymmetric_cryptography.signature(challenge)
        params.LocaleIds.append("en")
        if not username and not certificate:
            self._add_anonymous_auth(params)
        elif certificate:
            self._add_certificate_auth(params, certificate, challenge)
        else:
            self._add_user_auth(params, username, password)
        return self.uaclient.activate_session(params)

    def _add_anonymous_auth(self, params):
        params.UserIdentityToken = ua.AnonymousIdentityToken()
        params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.Anonymous, b"anonymous")

    def _add_certificate_auth(self, params, certificate, challenge):
        params.UserIdentityToken = ua.X509IdentityToken()
        params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.Certificate, b"certificate_basic256")
        params.UserIdentityToken.CertificateData = uacrypto.der_from_x509(certificate)
        # specs part 4, 5.6.3.1: the data to sign is created by appending
        # the last serverNonce to the serverCertificate
        sig = uacrypto.sign_sha1(self.user_private_key, challenge)
        params.UserTokenSignature = ua.SignatureData()
        params.UserTokenSignature.Algorithm = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"
        params.UserTokenSignature.Signature = sig

    def _add_user_auth(self, params, username, password):
        params.UserIdentityToken = ua.UserNameIdentityToken()
        params.UserIdentityToken.UserName = username
        policy_uri = self.server_policy_uri(ua.UserTokenType.UserName)
        if not policy_uri or policy_uri == security_policies.POLICY_NONE_URI:
            # see specs part 4, 7.36.3: if the token is NOT encrypted,
            # then the password only contains UTF-8 encoded password
            # and EncryptionAlgorithm is null
            if self._password:
                self.logger.warning("Sending plain-text password")
                params.UserIdentityToken.Password = password
            params.UserIdentityToken.EncryptionAlgorithm = None
        elif self._password:
            data, uri = self._encrypt_password(password, policy_uri)
            params.UserIdentityToken.Password = data
            params.UserIdentityToken.EncryptionAlgorithm = uri
        params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.UserName, b"username_basic256")

    def _encrypt_password(self, password, policy_uri):
        pubkey = uacrypto.x509_from_der(self.security_policy.server_certificate).public_key()
        # see specs part 4, 7.36.3: if the token is encrypted, password
        # shall be converted to UTF-8 and serialized with server nonce
        passwd = password.encode("utf8")
        if self._server_nonce is not None:
            passwd += self._server_nonce
        etoken = ua.ua_binary.Primitives.Bytes.pack(passwd)
        data, uri = security_policies.encrypt_asymmetric(pubkey, etoken, policy_uri)
        return data, uri

    def close_session(self):
        """
        Close session
        """
        if self.keepalive:
            self.keepalive.stop()
        return self.uaclient.close_session(True)

    def get_root_node(self):
        return self.get_node(ua.TwoByteNodeId(ua.ObjectIds.RootFolder))

    def get_objects_node(self):
        return self.get_node(ua.TwoByteNodeId(ua.ObjectIds.ObjectsFolder))

    def get_server_node(self):
        return self.get_node(ua.FourByteNodeId(ua.ObjectIds.Server))

    def get_node(self, nodeid):
        """
        Get node using NodeId object or a string representing a NodeId
        """
        return Node(self.uaclient, nodeid)

    def create_subscription(self, period, handler):
        """
        Create a subscription.
        returns a Subscription object which allow
        to subscribe to events or data on server
        handler argument is a class with data_change and/or event methods.
        period argument is either a publishing interval in milliseconds or a
        CreateSubscriptionParameters instance. The second option should be used,
        if the opcua-server has problems with the default options.
        These methods will be called when notfication from server are received.
        See example-client.py.
        Do not do expensive/slow or network operation from these methods
        since they are called directly from receiving thread. This is a design choice,
        start another thread if you need to do such a thing.
        """

        if isinstance(period, ua.CreateSubscriptionParameters):
            return Subscription(self.uaclient, period, handler)
        params = ua.CreateSubscriptionParameters()
        params.RequestedPublishingInterval = period
        params.RequestedLifetimeCount = 10000
        params.RequestedMaxKeepAliveCount = 3000
        params.MaxNotificationsPerPublish = 10000
        params.PublishingEnabled = True
        params.Priority = 0
        return Subscription(self.uaclient, params, handler)

    def get_namespace_array(self):
        ns_node = self.get_node(ua.NodeId(ua.ObjectIds.Server_NamespaceArray))
        return ns_node.get_value()

    def get_namespace_index(self, uri):
        uries = self.get_namespace_array()
        return uries.index(uri)

    def delete_nodes(self, nodes, recursive=False):
        return delete_nodes(self.uaclient, nodes, recursive)

    def import_xml(self, path):
        """
        Import nodes defined in xml
        """
        importer = XmlImporter(self)
        return importer.import_xml(path)

    def export_xml(self, nodes, path):
        """
        Export defined nodes to xml
        """
        exp = XmlExporter(self)
        exp.build_etree(nodes)
        return exp.write_xml(path)

    def register_namespace(self, uri):
        """
        Register a new namespace. Nodes should in custom namespace, not 0.
        This method is mainly implemented for symetry with server
        """
        ns_node = self.get_node(ua.NodeId(ua.ObjectIds.Server_NamespaceArray))
        uries = ns_node.get_value()
        if uri in uries:
            return uries.index(uri)
        uries.append(uri)
        ns_node.set_value(uries)
        return len(uries) - 1

    def load_type_definitions(self, nodes=None):
        return load_type_definitions(self, nodes)




1	1	from __future__ import division # support for python2
2	1	from threading import Thread, Condition
3	1	import logging
4	1	try:
5	1	from urllib.parse import urlparse
6	1	except ImportError: # support for python2
7	1	from urlparse import urlparse
8
9	1	from opcua import ua
10	1	from opcua.client.ua_client import UaClient
11	1	from opcua.common.xmlimporter import XmlImporter
12	1	from opcua.common.xmlexporter import XmlExporter
13	1	from opcua.common.node import Node
14	1	from opcua.common.manage_nodes import delete_nodes
15	1	from opcua.common.subscription import Subscription
16	1	from opcua.common import utils
17	1	from opcua.crypto import security_policies
18	1	from opcua.common.shortcuts import Shortcuts
19	1	from opcua.common.structures import load_type_definitions
20	1	use_crypto = True
21	1	try:
22	1	from opcua.crypto import uacrypto
23		except ImportError:
24		logging.getLogger(__name__).warning("cryptography is not installed, use of crypto disabled")
25		use_crypto = False
26
27
28	1	class KeepAlive(Thread):
29
30		"""
31		Used by Client to keep the session open.
32		OPCUA defines timeout both for sessions and secure channel
33		"""
34
35	1	def __init__(self, client, timeout):
36		"""
37		:param session_timeout: Timeout to re-new the session
38		in milliseconds.
39		"""
40	1	Thread.__init__(self)
41	1	self.logger = logging.getLogger(__name__)
42
43	1	self.client = client
44	1	self._dostop = False
45	1	self._cond = Condition()
46	1	self.timeout = timeout
47
48		# some server support no timeout, but we do not trust them
49	1	if self.timeout == 0:
50		self.timeout = 3600000 # 1 hour
51
52	1	def run(self):
53	1	self.logger.debug("starting keepalive thread with period of %s milliseconds", self.timeout)
54	1	server_state = self.client.get_node(ua.FourByteNodeId(ua.ObjectIds.Server_ServerStatus_State))
55	1	while not self._dostop:
56	1	with self._cond:
57	1	self._cond.wait(self.timeout / 1000)
58	1	if self._dostop:
59	1	break
60		self.logger.debug("renewing channel")
61		self.client.open_secure_channel(renew=True)
62		val = server_state.get_value()
63		self.logger.debug("server state is: %s ", val)
64	1	self.logger.debug("keepalive thread has stopped")
65
66	1	def stop(self):
67	1	self.logger.debug("stoping keepalive thread")
68	1	self._dostop = True
69	1	with self._cond:
70	1	self._cond.notify_all()
71
72
73	1	class Client(object):
74
75		"""
76		High level client to connect to an OPC-UA server.
77
78		This class makes it easy to connect and browse address space.
79		It attemps to expose as much functionality as possible
80		but if you want more flexibility it is possible and adviced to
81		use UaClient object, available as self.uaclient
82		which offers the raw OPC-UA services interface.
83		"""
84
85	1	def __init__(self, url, timeout=4):
86		"""
87
88		:param url: url of the server.
89		if you are unsure of url, write at least hostname
90		and port and call get_endpoints
91
92		:param timeout:
93		Each request sent to the server expects an answer within this
94		time. The timeout is specified in seconds.
95		"""
96	1	self.logger = logging.getLogger(__name__)
97	1	self.server_url = urlparse(url)
98		#take initial username and password from the url
99	1	self._username = self.server_url.username
100	1	self._password = self.server_url.password
101	1	self.name = "Pure Python Client"
102	1	self.description = self.name
103	1	self.application_uri = "urn:freeopcua:client"
104	1	self.product_uri = "urn:freeopcua.github.no:client"
105	1	self.security_policy = ua.SecurityPolicy()
106	1	self.secure_channel_id = None
107	1	self.secure_channel_timeout = 3600000 # 1 hour
108	1	self.session_timeout = 3600000 # 1 hour
109	1	self._policy_ids = []
110	1	self.uaclient = UaClient(timeout)
111	1	self.user_certificate = None
112	1	self.user_private_key = None
113	1	self._server_nonce = None
114	1	self._session_counter = 1
115	1	self.keepalive = None
116	1	self.nodes = Shortcuts(self.uaclient)
117	1	self.max_messagesize = 0 # No limits
118	1	self.max_chunkcount = 0 # No limits
119
120
121	1	def __enter__(self):
122	1	self.connect()
123	1	return self
124
125	1	def __exit__(self, exc_type, exc_value, traceback):
126	1	self.disconnect()
127
128	1	@staticmethod
129		def find_endpoint(endpoints, security_mode, policy_uri):
130		"""
131		Find endpoint with required security mode and policy URI
132		"""
133	1	for ep in endpoints:
134	1	if (ep.EndpointUrl.startswith(ua.OPC_TCP_SCHEME) and
135		ep.SecurityMode == security_mode and
136		ep.SecurityPolicyUri == policy_uri):
137	1	return ep
138	1	raise ua.UaError("No matching endpoints: {0}, {1}".format(security_mode, policy_uri))
139
140	1	def set_user(self, username):
141		"""
142		Set user name for the connection.
143		initial user from the URL will be overwritten
144		"""
145		self._username = username
146
147	1	def set_password(self, pwd):
148		"""
149		Set user password for the connection.
150		initial password from the URL will be overwritten
151		"""
152		self._password = pwd
153
154	1	def set_security_string(self, string):
155		"""
156		Set SecureConnection mode. String format:
157		Policy,Mode,certificate,private_key[,server_private_key]
158		where Policy is Basic128Rsa15 or Basic256,
159		Mode is Sign or SignAndEncrypt
160		certificate, private_key and server_private_key are
161		paths to .pem or .der files
162		Call this before connect()
163		"""
164	1	if not string:
165		return
166	1	parts = string.split(',')
167	1	if len(parts) < 4:
168		raise ua.UaError('Wrong format: `{0}`, expected at least 4 comma-separated values'.format(string))
169	1	policy_class = getattr(security_policies, 'SecurityPolicy' + parts[0])
170	1	mode = getattr(ua.MessageSecurityMode, parts[1])
171	1	return self.set_security(policy_class, parts[2], parts[3],
172		parts[4] if len(parts) >= 5 else None, mode)
173
174	1	def set_security(self, policy, certificate_path, private_key_path,
175		server_certificate_path=None,
176		mode=ua.MessageSecurityMode.SignAndEncrypt):
177		"""
178		Set SecureConnection mode.
179		Call this before connect()
180		"""
181	1	if server_certificate_path is None:
182		# load certificate from server's list of endpoints
183	1	endpoints = self.connect_and_get_server_endpoints()
184	1	endpoint = Client.find_endpoint(endpoints, mode, policy.URI)
185	1	server_cert = uacrypto.x509_from_der(endpoint.ServerCertificate)
186		else:
187		server_cert = uacrypto.load_certificate(server_certificate_path)
188	1	cert = uacrypto.load_certificate(certificate_path)
189	1	pk = uacrypto.load_private_key(private_key_path)
190	1	self.security_policy = policy(server_cert, cert, pk, mode)
191	1	self.uaclient.set_security(self.security_policy)
192
193	1	def load_client_certificate(self, path):
194		"""
195		load our certificate from file, either pem or der
196		"""
197		self.user_certificate = uacrypto.load_certificate(path)
198
199	1	def load_private_key(self, path):
200		"""
201		Load user private key. This is used for authenticating using certificate
202		"""
203		self.user_private_key = uacrypto.load_private_key(path)
204
205	1	def connect_and_get_server_endpoints(self):
206		"""
207		Connect, ask server for endpoints, and disconnect
208		"""
209	1	self.connect_socket()
210	1	try:
211	1	self.send_hello()
212	1	self.open_secure_channel()
213	1	endpoints = self.get_endpoints()
214	1	self.close_secure_channel()
215		finally:
216	1	self.disconnect_socket()
217	1	return endpoints
218
219	1	def connect_and_find_servers(self):
220		"""
221		Connect, ask server for a list of known servers, and disconnect
222		"""
223		self.connect_socket()
224		try:
225		self.send_hello()
226		self.open_secure_channel() # spec says it should not be necessary to open channel
227		servers = self.find_servers()
228		self.close_secure_channel()
229		finally:
230		self.disconnect_socket()
231		return servers
232
233	1	def connect_and_find_servers_on_network(self):
234		"""
235		Connect, ask server for a list of known servers on network, and disconnect
236		"""
237		self.connect_socket()
238		try:
239		self.send_hello()
240		self.open_secure_channel()
241		servers = self.find_servers_on_network()
242		self.close_secure_channel()
243		finally:
244		self.disconnect_socket()
245		return servers
246
247	1	def connect(self):
248		"""
249		High level method
250		Connect, create and activate session
251		"""
252	1	self.connect_socket()
253	1	try:
254	1	self.send_hello()
255	1	self.open_secure_channel()
256	1	self.create_session()
257		except:
258		self.disconnect_socket() # clean up open socket
259		raise
260	1	self.activate_session(username=self._username, password=self._password, certificate=self.user_certificate)
261
262	1	def disconnect(self):
263		"""
264		High level method
265		Close session, secure channel and socket
266		"""
267	1	try:
268	1	self.close_session()
269	1	self.close_secure_channel()
270		finally:
271	1	self.disconnect_socket()
272
273	1	def connect_socket(self):
274		"""
275		connect to socket defined in url
276		"""
277	1	self.uaclient.connect_socket(self.server_url.hostname, self.server_url.port)
278
279	1	def disconnect_socket(self):
280	1	self.uaclient.disconnect_socket()
281
282	1	def send_hello(self):
283		"""
284		Send OPC-UA hello to server
285		"""
286	1	ack = self.uaclient.send_hello(self.server_url.geturl(), self.max_messagesize, self.max_chunkcount)
287		# FIXME check ack
288
289	1	def open_secure_channel(self, renew=False):
290		"""
291		Open secure channel, if renew is True, renew channel
292		"""
293	1	params = ua.OpenSecureChannelParameters()
294	1	params.ClientProtocolVersion = 0
295	1	params.RequestType = ua.SecurityTokenRequestType.Issue
296	1	if renew:
297		params.RequestType = ua.SecurityTokenRequestType.Renew
298	1	params.SecurityMode = self.security_policy.Mode
299	1	params.RequestedLifetime = self.secure_channel_timeout
300	1	nonce = utils.create_nonce(self.security_policy.symmetric_key_size) # length should be equal to the length of key of symmetric encryption
301	1	params.ClientNonce = nonce # this nonce is used to create a symmetric key
302	1	result = self.uaclient.open_secure_channel(params)
303	1	self.security_policy.make_symmetric_key(nonce, result.ServerNonce)
304	1	self.secure_channel_timeout = result.SecurityToken.RevisedLifetime
305
306	1	def close_secure_channel(self):
307	1	return self.uaclient.close_secure_channel()
308
309	1	def get_endpoints(self):
310	1	params = ua.GetEndpointsParameters()
311	1	params.EndpointUrl = self.server_url.geturl()
312	1	return self.uaclient.get_endpoints(params)
313
314	1	def register_server(self, server, discovery_configuration=None):
315		"""
316		register a server to discovery server
317		if discovery_configuration is provided, the newer register_server2 service call is used
318		"""
319	1	serv = ua.RegisteredServer()
320	1	serv.ServerUri = server.application_uri
321	1	serv.ProductUri = server.product_uri
322	1	serv.DiscoveryUrls = [server.endpoint.geturl()]
323	1	serv.ServerType = server.application_type
324	1	serv.ServerNames = [ua.LocalizedText(server.name)]
325	1	serv.IsOnline = True
326	1	if discovery_configuration:
327		params = ua.RegisterServer2Parameters()
328		params.Server = serv
329		params.DiscoveryConfiguration = discovery_configuration
330		return self.uaclient.register_server2(params)
331		else:
332	1	return self.uaclient.register_server(serv)
333
334	1	def find_servers(self, uris=None):
335		"""
336		send a FindServer request to the server. The answer should be a list of
337		servers the server knows about
338		A list of uris can be provided, only server having matching uris will be returned
339		"""
340	1	if uris is None:
341	1	uris = []
342	1	params = ua.FindServersParameters()
343	1	params.EndpointUrl = self.server_url.geturl()
344	1	params.ServerUris = uris
345	1	return self.uaclient.find_servers(params)
346
347	1	def find_servers_on_network(self):
348		params = ua.FindServersOnNetworkParameters()
349		return self.uaclient.find_servers_on_network(params)
350
351	1	def create_session(self):
352		"""
353		send a CreateSessionRequest to server with reasonable parameters.
354		If you want o modify settings look at code of this methods
355		and make your own
356		"""
357	1	desc = ua.ApplicationDescription()
358	1	desc.ApplicationUri = self.application_uri
359	1	desc.ProductUri = self.product_uri
360	1	desc.ApplicationName = ua.LocalizedText(self.name)
361	1	desc.ApplicationType = ua.ApplicationType.Client
362
363	1	params = ua.CreateSessionParameters()
364	1	nonce = utils.create_nonce(32) # at least 32 random bytes for server to prove possession of private key (specs part 4, 5.6.2.2)
365	1	params.ClientNonce = nonce
366	1	params.ClientCertificate = self.security_policy.client_certificate
367	1	params.ClientDescription = desc
368	1	params.EndpointUrl = self.server_url.geturl()
369	1	params.SessionName = self.description + " Session" + str(self._session_counter)
370	1	params.RequestedSessionTimeout = 3600000
371	1	params.MaxResponseMessageSize = 0 # means no max size
372	1	response = self.uaclient.create_session(params)
373	1	if self.security_policy.client_certificate is None:
374	1	data = nonce
375		else:
376	1	data = self.security_policy.client_certificate + nonce
377	1	self.security_policy.asymmetric_cryptography.verify(data, response.ServerSignature.Signature)
378	1	self._server_nonce = response.ServerNonce
379	1	if not self.security_policy.server_certificate:
380	1	self.security_policy.server_certificate = response.ServerCertificate
381	1	elif self.security_policy.server_certificate != response.ServerCertificate:
382		raise ua.UaError("Server certificate mismatch")
383		# remember PolicyId's: we will use them in activate_session()
384	1	ep = Client.find_endpoint(response.ServerEndpoints, self.security_policy.Mode, self.security_policy.URI)
385	1	self._policy_ids = ep.UserIdentityTokens
386	1	self.session_timeout = response.RevisedSessionTimeout
387	1	self.keepalive = KeepAlive(self, min(self.session_timeout, self.secure_channel_timeout) * 0.7) # 0.7 is from spec
388	1	self.keepalive.start()
389	1	return response
390
391	1	def server_policy_id(self, token_type, default):
392		"""
393		Find PolicyId of server's UserTokenPolicy by token_type.
394		Return default if there's no matching UserTokenPolicy.
395		"""
396	1	for policy in self._policy_ids:
397	1	if policy.TokenType == token_type:
398	1	return policy.PolicyId
399		return default
400
401	1	def server_policy_uri(self, token_type):
402		"""
403		Find SecurityPolicyUri of server's UserTokenPolicy by token_type.
404		If SecurityPolicyUri is empty, use default SecurityPolicyUri
405		of the endpoint
406		"""
407	1	for policy in self._policy_ids:
408	1	if policy.TokenType == token_type:
409	1	if policy.SecurityPolicyUri:
410		return policy.SecurityPolicyUri
411		else: # empty URI means "use this endpoint's policy URI"
412	1	return self.security_policy.URI
413		return self.security_policy.URI
414
415	1	def activate_session(self, username=None, password=None, certificate=None):
416		"""
417		Activate session using either username and password or private_key
418		"""
419	1	params = ua.ActivateSessionParameters()
420	1	challenge = b""
421	1	if self.security_policy.server_certificate is not None:
422	1	challenge += self.security_policy.server_certificate
423	1	if self._server_nonce is not None:
424	1	challenge += self._server_nonce
425	1	params.ClientSignature.Algorithm = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"
426	1	params.ClientSignature.Signature = self.security_policy.asymmetric_cryptography.signature(challenge)
427	1	params.LocaleIds.append("en")
428	1	if not username and not certificate:
429	1	self._add_anonymous_auth(params)
430	1	elif certificate:
431		self._add_certificate_auth(params, certificate, challenge)
432		else:
433	1	self._add_user_auth(params, username, password)
434	1	return self.uaclient.activate_session(params)
435
436	1	def _add_anonymous_auth(self, params):
437	1	params.UserIdentityToken = ua.AnonymousIdentityToken()
438	1	params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.Anonymous, b"anonymous")
439
440	1	def _add_certificate_auth(self, params, certificate, challenge):
441		params.UserIdentityToken = ua.X509IdentityToken()
442		params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.Certificate, b"certificate_basic256")
443		params.UserIdentityToken.CertificateData = uacrypto.der_from_x509(certificate)
444		# specs part 4, 5.6.3.1: the data to sign is created by appending
445		# the last serverNonce to the serverCertificate
446		sig = uacrypto.sign_sha1(self.user_private_key, challenge)
447		params.UserTokenSignature = ua.SignatureData()
448		params.UserTokenSignature.Algorithm = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"
449		params.UserTokenSignature.Signature = sig
450
451	1	def _add_user_auth(self, params, username, password):
452	1	params.UserIdentityToken = ua.UserNameIdentityToken()
453	1	params.UserIdentityToken.UserName = username
454	1	policy_uri = self.server_policy_uri(ua.UserTokenType.UserName)
455	1	if not policy_uri or policy_uri == security_policies.POLICY_NONE_URI:
456		# see specs part 4, 7.36.3: if the token is NOT encrypted,
457		# then the password only contains UTF-8 encoded password
458		# and EncryptionAlgorithm is null
459	1	if self._password:
460		self.logger.warning("Sending plain-text password")
461		params.UserIdentityToken.Password = password
462	1	params.UserIdentityToken.EncryptionAlgorithm = None
463		elif self._password:
464		data, uri = self._encrypt_password(password, policy_uri)
465		params.UserIdentityToken.Password = data
466		params.UserIdentityToken.EncryptionAlgorithm = uri
467	1	params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.UserName, b"username_basic256")
468
469	1	def _encrypt_password(self, password, policy_uri):
470		pubkey = uacrypto.x509_from_der(self.security_policy.server_certificate).public_key()
471		# see specs part 4, 7.36.3: if the token is encrypted, password
472		# shall be converted to UTF-8 and serialized with server nonce
473		passwd = password.encode("utf8")
474		if self._server_nonce is not None:
475		passwd += self._server_nonce
476		etoken = ua.ua_binary.Primitives.Bytes.pack(passwd)
477		data, uri = security_policies.encrypt_asymmetric(pubkey, etoken, policy_uri)
478		return data, uri
479
480	1	def close_session(self):
481		"""
482		Close session
483		"""
484	1	if self.keepalive:
485	1	self.keepalive.stop()
486	1	return self.uaclient.close_session(True)
487
488	1	def get_root_node(self):
489	1	return self.get_node(ua.TwoByteNodeId(ua.ObjectIds.RootFolder))
490
491	1	def get_objects_node(self):
492	1	return self.get_node(ua.TwoByteNodeId(ua.ObjectIds.ObjectsFolder))
493
494	1	def get_server_node(self):
495	1	return self.get_node(ua.FourByteNodeId(ua.ObjectIds.Server))
496
497	1	def get_node(self, nodeid):
498		"""
499		Get node using NodeId object or a string representing a NodeId
500		"""
501	1	return Node(self.uaclient, nodeid)
502
503	1	def create_subscription(self, period, handler):
504		"""
505		Create a subscription.
506		returns a Subscription object which allow
507		to subscribe to events or data on server
508		handler argument is a class with data_change and/or event methods.
509		period argument is either a publishing interval in milliseconds or a
510		CreateSubscriptionParameters instance. The second option should be used,
511		if the opcua-server has problems with the default options.
512		These methods will be called when notfication from server are received.
513		See example-client.py.
514		Do not do expensive/slow or network operation from these methods
515		since they are called directly from receiving thread. This is a design choice,
516		start another thread if you need to do such a thing.
517		"""
518
519	1	if isinstance(period, ua.CreateSubscriptionParameters):
520		return Subscription(self.uaclient, period, handler)
521	1	params = ua.CreateSubscriptionParameters()
522	1	params.RequestedPublishingInterval = period
523	1	params.RequestedLifetimeCount = 10000
524	1	params.RequestedMaxKeepAliveCount = 3000
525	1	params.MaxNotificationsPerPublish = 10000
526	1	params.PublishingEnabled = True
527	1	params.Priority = 0
528	1	return Subscription(self.uaclient, params, handler)
529
530	1	def get_namespace_array(self):
531	1	ns_node = self.get_node(ua.NodeId(ua.ObjectIds.Server_NamespaceArray))
532	1	return ns_node.get_value()
533
534	1	def get_namespace_index(self, uri):
535	1	uries = self.get_namespace_array()
536	1	return uries.index(uri)
537
538	1	def delete_nodes(self, nodes, recursive=False):
539	1	return delete_nodes(self.uaclient, nodes, recursive)
540
541	1	def import_xml(self, path):
542		"""
543		Import nodes defined in xml
544		"""
545	1	importer = XmlImporter(self)
546	1	return importer.import_xml(path)
547
548	1	def export_xml(self, nodes, path):
549		"""
550		Export defined nodes to xml
551		"""
552	1	exp = XmlExporter(self)
553	1	exp.build_etree(nodes)
554	1	return exp.write_xml(path)
555
556	1	def register_namespace(self, uri):
557		"""
558		Register a new namespace. Nodes should in custom namespace, not 0.
559		This method is mainly implemented for symetry with server
560		"""
561	1	ns_node = self.get_node(ua.NodeId(ua.ObjectIds.Server_NamespaceArray))
562	1	uries = ns_node.get_value()
563	1	if uri in uries:
564	1	return uries.index(uri)
565	1	uries.append(uri)
566	1	ns_node.set_value(uries)
567	1	return len(uries) - 1
568
569	1	def load_type_definitions(self, nodes=None):
570		return load_type_definitions(self, nodes)
571
572
573

FreeOpcUa / python-opcua

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Client.connect_and_find_servers() A

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