Client.create_session() - Code Metrics - Inspection of "Reap Client-KeepAlive Threads for reconnect" - FreeOpcUa/python-opcua - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Pull Request — master (#534)

unknown

created 2017-12-11 14:14 UTC

Client.create_session() B

↳ Parent: Project

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	34
CRAP Score	5.0005

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	5
c	1
b	0
f	0
dl	0
loc	44
ccs	34
cts	35
cp	0.9714
crap	5.0005
rs	8.0894

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()
        self.send_hello()
        self.open_secure_channel()
        endpoints = self.get_endpoints()
        self.close_secure_channel()
        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()
        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()
        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()
        self.send_hello()
        self.open_secure_channel()
        servers = self.find_servers_on_network()
        self.close_secure_channel()
        self.disconnect_socket()
        return servers

    def connect(self):
        """
        High level method
        Connect, create and activate session
        """
        self.connect_socket()
        self.send_hello()
        self.open_secure_channel()
        self.create_session()
        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
        # In case there was an existing session, try to reap existing KeepAlive-Thread
        try:
            self.keepalive.stop()
        except AttributeError:
            pass
        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	self.send_hello()
211	1	self.open_secure_channel()
212	1	endpoints = self.get_endpoints()
213	1	self.close_secure_channel()
214	1	self.disconnect_socket()
215	1	return endpoints
216
217	1	def connect_and_find_servers(self):
218		"""
219		Connect, ask server for a list of known servers, and disconnect
220		"""
221		self.connect_socket()
222		self.send_hello()
223		self.open_secure_channel() # spec says it should not be necessary to open channel
224		servers = self.find_servers()
225		self.close_secure_channel()
226		self.disconnect_socket()
227		return servers
228
229	1	def connect_and_find_servers_on_network(self):
230		"""
231		Connect, ask server for a list of known servers on network, and disconnect
232		"""
233		self.connect_socket()
234		self.send_hello()
235		self.open_secure_channel()
236		servers = self.find_servers_on_network()
237		self.close_secure_channel()
238		self.disconnect_socket()
239		return servers
240
241	1	def connect(self):
242		"""
243		High level method
244		Connect, create and activate session
245		"""
246	1	self.connect_socket()
247	1	self.send_hello()
248	1	self.open_secure_channel()
249	1	self.create_session()
250	1	self.activate_session(username=self._username, password=self._password, certificate=self.user_certificate)
251
252	1	def disconnect(self):
253		"""
254		High level method
255		Close session, secure channel and socket
256		"""
257	1	try:
258	1	self.close_session()
259	1	self.close_secure_channel()
260		finally:
261	1	self.disconnect_socket()
262
263	1	def connect_socket(self):
264		"""
265		connect to socket defined in url
266		"""
267	1	self.uaclient.connect_socket(self.server_url.hostname, self.server_url.port)
268
269	1	def disconnect_socket(self):
270	1	self.uaclient.disconnect_socket()
271
272	1	def send_hello(self):
273		"""
274		Send OPC-UA hello to server
275		"""
276	1	ack = self.uaclient.send_hello(self.server_url.geturl(), self.max_messagesize, self.max_chunkcount)
277		# FIXME check ack
278
279	1	def open_secure_channel(self, renew=False):
280		"""
281		Open secure channel, if renew is True, renew channel
282		"""
283	1	params = ua.OpenSecureChannelParameters()
284	1	params.ClientProtocolVersion = 0
285	1	params.RequestType = ua.SecurityTokenRequestType.Issue
286	1	if renew:
287		params.RequestType = ua.SecurityTokenRequestType.Renew
288	1	params.SecurityMode = self.security_policy.Mode
289	1	params.RequestedLifetime = self.secure_channel_timeout
290	1	nonce = utils.create_nonce(self.security_policy.symmetric_key_size) # length should be equal to the length of key of symmetric encryption
291	1	params.ClientNonce = nonce # this nonce is used to create a symmetric key
292	1	result = self.uaclient.open_secure_channel(params)
293	1	self.security_policy.make_symmetric_key(nonce, result.ServerNonce)
294	1	self.secure_channel_timeout = result.SecurityToken.RevisedLifetime
295
296	1	def close_secure_channel(self):
297	1	return self.uaclient.close_secure_channel()
298
299	1	def get_endpoints(self):
300	1	params = ua.GetEndpointsParameters()
301	1	params.EndpointUrl = self.server_url.geturl()
302	1	return self.uaclient.get_endpoints(params)
303
304	1	def register_server(self, server, discovery_configuration=None):
305		"""
306		register a server to discovery server
307		if discovery_configuration is provided, the newer register_server2 service call is used
308		"""
309	1	serv = ua.RegisteredServer()
310	1	serv.ServerUri = server.application_uri
311	1	serv.ProductUri = server.product_uri
312	1	serv.DiscoveryUrls = [server.endpoint.geturl()]
313	1	serv.ServerType = server.application_type
314	1	serv.ServerNames = [ua.LocalizedText(server.name)]
315	1	serv.IsOnline = True
316	1	if discovery_configuration:
317		params = ua.RegisterServer2Parameters()
318		params.Server = serv
319		params.DiscoveryConfiguration = discovery_configuration
320		return self.uaclient.register_server2(params)
321		else:
322	1	return self.uaclient.register_server(serv)
323
324	1	def find_servers(self, uris=None):
325		"""
326		send a FindServer request to the server. The answer should be a list of
327		servers the server knows about
328		A list of uris can be provided, only server having matching uris will be returned
329		"""
330	1	if uris is None:
331	1	uris = []
332	1	params = ua.FindServersParameters()
333	1	params.EndpointUrl = self.server_url.geturl()
334	1	params.ServerUris = uris
335	1	return self.uaclient.find_servers(params)
336
337	1	def find_servers_on_network(self):
338		params = ua.FindServersOnNetworkParameters()
339		return self.uaclient.find_servers_on_network(params)
340
341	1	def create_session(self):
342		"""
343		send a CreateSessionRequest to server with reasonable parameters.
344		If you want o modify settings look at code of this methods
345		and make your own
346		"""
347	1	desc = ua.ApplicationDescription()
348	1	desc.ApplicationUri = self.application_uri
349	1	desc.ProductUri = self.product_uri
350	1	desc.ApplicationName = ua.LocalizedText(self.name)
351	1	desc.ApplicationType = ua.ApplicationType.Client
352
353	1	params = ua.CreateSessionParameters()
354	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)
355	1	params.ClientNonce = nonce
356	1	params.ClientCertificate = self.security_policy.client_certificate
357	1	params.ClientDescription = desc
358	1	params.EndpointUrl = self.server_url.geturl()
359	1	params.SessionName = self.description + " Session" + str(self._session_counter)
360	1	params.RequestedSessionTimeout = 3600000
361	1	params.MaxResponseMessageSize = 0 # means no max size
362	1	response = self.uaclient.create_session(params)
363	1	if self.security_policy.client_certificate is None:
364	1	data = nonce
365		else:
366	1	data = self.security_policy.client_certificate + nonce
367	1	self.security_policy.asymmetric_cryptography.verify(data, response.ServerSignature.Signature)
368	1	self._server_nonce = response.ServerNonce
369	1	if not self.security_policy.server_certificate:
370	1	self.security_policy.server_certificate = response.ServerCertificate
371	1	elif self.security_policy.server_certificate != response.ServerCertificate:
372		raise ua.UaError("Server certificate mismatch")
373		# remember PolicyId's: we will use them in activate_session()
374	1	ep = Client.find_endpoint(response.ServerEndpoints, self.security_policy.Mode, self.security_policy.URI)
375	1	self._policy_ids = ep.UserIdentityTokens
376	1	self.session_timeout = response.RevisedSessionTimeout
377		# In case there was an existing session, try to reap existing KeepAlive-Thread
378	1	try:
379	1	self.keepalive.stop()
380	1	except AttributeError:
381	1	pass
382	1	self.keepalive = KeepAlive(self, min(self.session_timeout, self.secure_channel_timeout) * 0.7) # 0.7 is from spec
383	1	self.keepalive.start()
384	1	return response
385
386	1	def server_policy_id(self, token_type, default):
387		"""
388		Find PolicyId of server's UserTokenPolicy by token_type.
389		Return default if there's no matching UserTokenPolicy.
390		"""
391	1	for policy in self._policy_ids:
392	1	if policy.TokenType == token_type:
393	1	return policy.PolicyId
394		return default
395
396	1	def server_policy_uri(self, token_type):
397		"""
398		Find SecurityPolicyUri of server's UserTokenPolicy by token_type.
399		If SecurityPolicyUri is empty, use default SecurityPolicyUri
400		of the endpoint
401		"""
402	1	for policy in self._policy_ids:
403	1	if policy.TokenType == token_type:
404	1	if policy.SecurityPolicyUri:
405		return policy.SecurityPolicyUri
406		else: # empty URI means "use this endpoint's policy URI"
407	1	return self.security_policy.URI
408		return self.security_policy.URI
409
410	1	def activate_session(self, username=None, password=None, certificate=None):
411		"""
412		Activate session using either username and password or private_key
413		"""
414	1	params = ua.ActivateSessionParameters()
415	1	challenge = b""
416	1	if self.security_policy.server_certificate is not None:
417	1	challenge += self.security_policy.server_certificate
418	1	if self._server_nonce is not None:
419	1	challenge += self._server_nonce
420	1	params.ClientSignature.Algorithm = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"
421	1	params.ClientSignature.Signature = self.security_policy.asymmetric_cryptography.signature(challenge)
422	1	params.LocaleIds.append("en")
423	1	if not username and not certificate:
424	1	self._add_anonymous_auth(params)
425	1	elif certificate:
426		self._add_certificate_auth(params, certificate, challenge)
427		else:
428	1	self._add_user_auth(params, username, password)
429	1	return self.uaclient.activate_session(params)
430
431	1	def _add_anonymous_auth(self, params):
432	1	params.UserIdentityToken = ua.AnonymousIdentityToken()
433	1	params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.Anonymous, b"anonymous")
434
435	1	def _add_certificate_auth(self, params, certificate, challenge):
436		params.UserIdentityToken = ua.X509IdentityToken()
437		params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.Certificate, b"certificate_basic256")
438		params.UserIdentityToken.CertificateData = uacrypto.der_from_x509(certificate)
439		# specs part 4, 5.6.3.1: the data to sign is created by appending
440		# the last serverNonce to the serverCertificate
441		sig = uacrypto.sign_sha1(self.user_private_key, challenge)
442		params.UserTokenSignature = ua.SignatureData()
443		params.UserTokenSignature.Algorithm = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"
444		params.UserTokenSignature.Signature = sig
445
446	1	def _add_user_auth(self, params, username, password):
447	1	params.UserIdentityToken = ua.UserNameIdentityToken()
448	1	params.UserIdentityToken.UserName = username
449	1	policy_uri = self.server_policy_uri(ua.UserTokenType.UserName)
450	1	if not policy_uri or policy_uri == security_policies.POLICY_NONE_URI:
451		# see specs part 4, 7.36.3: if the token is NOT encrypted,
452		# then the password only contains UTF-8 encoded password
453		# and EncryptionAlgorithm is null
454	1	if self._password:
455		self.logger.warning("Sending plain-text password")
456		params.UserIdentityToken.Password = password
457	1	params.UserIdentityToken.EncryptionAlgorithm = None
458		elif self._password:
459		data, uri = self._encrypt_password(password, policy_uri)
460		params.UserIdentityToken.Password = data
461		params.UserIdentityToken.EncryptionAlgorithm = uri
462	1	params.UserIdentityToken.PolicyId = self.server_policy_id(ua.UserTokenType.UserName, b"username_basic256")
463
464	1	def _encrypt_password(self, password, policy_uri):
465		pubkey = uacrypto.x509_from_der(self.security_policy.server_certificate).public_key()
466		# see specs part 4, 7.36.3: if the token is encrypted, password
467		# shall be converted to UTF-8 and serialized with server nonce
468		passwd = password.encode("utf8")
469		if self._server_nonce is not None:
470		passwd += self._server_nonce
471		etoken = ua.ua_binary.Primitives.Bytes.pack(passwd)
472		data, uri = security_policies.encrypt_asymmetric(pubkey, etoken, policy_uri)
473		return data, uri
474
475	1	def close_session(self):
476		"""
477		Close session
478		"""
479	1	if self.keepalive:
480	1	self.keepalive.stop()
481	1	return self.uaclient.close_session(True)
482
483	1	def get_root_node(self):
484	1	return self.get_node(ua.TwoByteNodeId(ua.ObjectIds.RootFolder))
485
486	1	def get_objects_node(self):
487	1	return self.get_node(ua.TwoByteNodeId(ua.ObjectIds.ObjectsFolder))
488
489	1	def get_server_node(self):
490	1	return self.get_node(ua.FourByteNodeId(ua.ObjectIds.Server))
491
492	1	def get_node(self, nodeid):
493		"""
494		Get node using NodeId object or a string representing a NodeId
495		"""
496	1	return Node(self.uaclient, nodeid)
497
498	1	def create_subscription(self, period, handler):
499		"""
500		Create a subscription.
501		returns a Subscription object which allow
502		to subscribe to events or data on server
503		handler argument is a class with data_change and/or event methods.
504		period argument is either a publishing interval in milliseconds or a
505		CreateSubscriptionParameters instance. The second option should be used,
506		if the opcua-server has problems with the default options.
507		These methods will be called when notfication from server are received.
508		See example-client.py.
509		Do not do expensive/slow or network operation from these methods
510		since they are called directly from receiving thread. This is a design choice,
511		start another thread if you need to do such a thing.
512		"""
513
514	1	if isinstance(period, ua.CreateSubscriptionParameters):
515		return Subscription(self.uaclient, period, handler)
516	1	params = ua.CreateSubscriptionParameters()
517	1	params.RequestedPublishingInterval = period
518	1	params.RequestedLifetimeCount = 10000
519	1	params.RequestedMaxKeepAliveCount = 3000
520	1	params.MaxNotificationsPerPublish = 10000
521	1	params.PublishingEnabled = True
522	1	params.Priority = 0
523	1	return Subscription(self.uaclient, params, handler)
524
525	1	def get_namespace_array(self):
526	1	ns_node = self.get_node(ua.NodeId(ua.ObjectIds.Server_NamespaceArray))
527	1	return ns_node.get_value()
528
529	1	def get_namespace_index(self, uri):
530	1	uries = self.get_namespace_array()
531	1	return uries.index(uri)
532
533	1	def delete_nodes(self, nodes, recursive=False):
534	1	return delete_nodes(self.uaclient, nodes, recursive)
535
536	1	def import_xml(self, path):
537		"""
538		Import nodes defined in xml
539		"""
540	1	importer = XmlImporter(self)
541	1	return importer.import_xml(path)
542
543	1	def export_xml(self, nodes, path):
544		"""
545		Export defined nodes to xml
546		"""
547	1	exp = XmlExporter(self)
548	1	exp.build_etree(nodes)
549	1	return exp.write_xml(path)
550
551	1	def register_namespace(self, uri):
552		"""
553		Register a new namespace. Nodes should in custom namespace, not 0.
554		This method is mainly implemented for symetry with server
555		"""
556	1	ns_node = self.get_node(ua.NodeId(ua.ObjectIds.Server_NamespaceArray))
557	1	uries = ns_node.get_value()
558	1	if uri in uries:
559	1	return uries.index(uri)
560	1	uries.append(uri)
561	1	ns_node.set_value(uries)
562	1	return len(uries) - 1
563
564	1	def load_type_definitions(self, nodes=None):
565		return load_type_definitions(self, nodes)
566
567
568

FreeOpcUa / python-opcua

Pull Request — master (#534)

Client.create_session() B

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