244 lines
8.8 KiB
Python
244 lines
8.8 KiB
Python
"""
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SleekXMPP: The Sleek XMPP Library
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Copyright (C) 2011 Nathanael C. Fritz
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This file is part of SleekXMPP.
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See the file LICENSE for copying permission.
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"""
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import ssl
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import logging
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from sleekxmpp.util import sasl
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from sleekxmpp.util.stringprep_profiles import StringPrepError
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from sleekxmpp.stanza import StreamFeatures
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from sleekxmpp.xmlstream import RestartStream, register_stanza_plugin
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from sleekxmpp.plugins import BasePlugin
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from sleekxmpp.xmlstream.matcher import MatchXPath
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from sleekxmpp.xmlstream.handler import Callback
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from sleekxmpp.features.feature_mechanisms import stanza
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log = logging.getLogger(__name__)
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class FeatureMechanisms(BasePlugin):
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name = 'feature_mechanisms'
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description = 'RFC 6120: Stream Feature: SASL'
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dependencies = set()
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stanza = stanza
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default_config = {
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'use_mech': None,
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'use_mechs': None,
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'min_mech': None,
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'sasl_callback': None,
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'security_callback': None,
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'encrypted_plain': True,
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'unencrypted_plain': False,
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'unencrypted_digest': False,
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'unencrypted_cram': False,
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'unencrypted_scram': True,
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'order': 100
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}
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def plugin_init(self):
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if self.sasl_callback is None:
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self.sasl_callback = self._default_credentials
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if self.security_callback is None:
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self.security_callback = self._default_security
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creds = self.sasl_callback(set(['username']), set())
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if not self.use_mech and not creds['username']:
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self.use_mech = 'ANONYMOUS'
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self.mech = None
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self.mech_list = set()
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self.attempted_mechs = set()
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register_stanza_plugin(StreamFeatures, stanza.Mechanisms)
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self.xmpp.register_stanza(stanza.Success)
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self.xmpp.register_stanza(stanza.Failure)
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self.xmpp.register_stanza(stanza.Auth)
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self.xmpp.register_stanza(stanza.Challenge)
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self.xmpp.register_stanza(stanza.Response)
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self.xmpp.register_stanza(stanza.Abort)
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self.xmpp.register_handler(
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Callback('SASL Success',
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MatchXPath(stanza.Success.tag_name()),
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self._handle_success,
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instream=True))
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self.xmpp.register_handler(
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Callback('SASL Failure',
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MatchXPath(stanza.Failure.tag_name()),
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self._handle_fail,
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instream=True))
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self.xmpp.register_handler(
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Callback('SASL Challenge',
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MatchXPath(stanza.Challenge.tag_name()),
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self._handle_challenge))
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self.xmpp.register_feature('mechanisms',
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self._handle_sasl_auth,
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restart=True,
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order=self.order)
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def _default_credentials(self, required_values, optional_values):
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creds = self.xmpp.credentials
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result = {}
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values = required_values.union(optional_values)
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for value in values:
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if value == 'username':
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result[value] = creds.get('username', self.xmpp.requested_jid.user)
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elif value == 'email':
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jid = self.xmpp.requested_jid.bare
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result[value] = creds.get('email', jid)
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elif value == 'channel_binding':
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if hasattr(self.xmpp.socket, 'get_channel_binding'):
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result[value] = self.xmpp.socket.get_channel_binding()
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else:
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log.debug("Channel binding not supported.")
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log.debug("Use Python 3.3+ for channel binding and " + \
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"SCRAM-SHA-1-PLUS support")
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result[value] = None
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elif value == 'host':
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result[value] = creds.get('host', self.xmpp.requested_jid.domain)
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elif value == 'realm':
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result[value] = creds.get('realm', self.xmpp.requested_jid.domain)
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elif value == 'service-name':
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result[value] = creds.get('service-name', self.xmpp._service_name)
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elif value == 'service':
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result[value] = creds.get('service', 'xmpp')
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elif value in creds:
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result[value] = creds[value]
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return result
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def _default_security(self, values):
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result = {}
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for value in values:
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if value == 'encrypted':
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if 'starttls' in self.xmpp.features:
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result[value] = True
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elif isinstance(self.xmpp.socket, ssl.SSLSocket):
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result[value] = True
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else:
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result[value] = False
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else:
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result[value] = self.config.get(value, False)
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return result
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def _handle_sasl_auth(self, features):
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"""
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Handle authenticating using SASL.
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Arguments:
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features -- The stream features stanza.
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"""
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if 'mechanisms' in self.xmpp.features:
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# SASL authentication has already succeeded, but the
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# server has incorrectly offered it again.
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return False
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enforce_limit = False
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limited_mechs = self.use_mechs
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if limited_mechs is None:
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limited_mechs = set()
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elif limited_mechs and not isinstance(limited_mechs, set):
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limited_mechs = set(limited_mechs)
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enforce_limit = True
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if self.use_mech:
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limited_mechs.add(self.use_mech)
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enforce_limit = True
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if enforce_limit:
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self.use_mechs = limited_mechs
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self.mech_list = set(features['mechanisms'])
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return self._send_auth()
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def _send_auth(self):
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mech_list = self.mech_list - self.attempted_mechs
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try:
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self.mech = sasl.choose(mech_list,
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self.sasl_callback,
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self.security_callback,
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limit=self.use_mechs,
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min_mech=self.min_mech)
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except sasl.SASLNoAppropriateMechanism:
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log.error("No appropriate login method.")
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self.xmpp.event("no_auth", direct=True)
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self.xmpp.event("failed_auth", direct=True)
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self.attempted_mechs = set()
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return self.xmpp.disconnect()
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except StringPrepError:
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log.exception("A credential value did not pass SASLprep.")
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self.xmpp.disconnect()
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resp = stanza.Auth(self.xmpp)
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resp['mechanism'] = self.mech.name
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try:
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resp['value'] = self.mech.process()
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except sasl.SASLCancelled:
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self.attempted_mechs.add(self.mech.name)
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self._send_auth()
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except sasl.SASLFailed:
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self.attempted_mechs.add(self.mech.name)
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self._send_auth()
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except sasl.SASLMutualAuthFailed:
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log.error("Mutual authentication failed! " + \
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"A security breach is possible.")
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self.attempted_mechs.add(self.mech.name)
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self.xmpp.disconnect()
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else:
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resp.send(now=True)
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return True
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def _handle_challenge(self, stanza):
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"""SASL challenge received. Process and send response."""
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resp = self.stanza.Response(self.xmpp)
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try:
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resp['value'] = self.mech.process(stanza['value'])
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except sasl.SASLCancelled:
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self.stanza.Abort(self.xmpp).send()
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except sasl.SASLFailed:
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self.stanza.Abort(self.xmpp).send()
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except sasl.SASLMutualAuthFailed:
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log.error("Mutual authentication failed! " + \
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"A security breach is possible.")
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self.attempted_mechs.add(self.mech.name)
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self.xmpp.disconnect()
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else:
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if resp.get_value() == '':
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resp.del_value()
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resp.send(now=True)
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def _handle_success(self, stanza):
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"""SASL authentication succeeded. Restart the stream."""
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try:
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final = self.mech.process(stanza['value'])
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except sasl.SASLMutualAuthFailed:
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log.error("Mutual authentication failed! " + \
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"A security breach is possible.")
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self.attempted_mechs.add(self.mech.name)
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self.xmpp.disconnect()
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else:
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self.attempted_mechs = set()
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self.xmpp.authenticated = True
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self.xmpp.features.add('mechanisms')
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self.xmpp.event('auth_success', stanza, direct=True)
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raise RestartStream()
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def _handle_fail(self, stanza):
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"""SASL authentication failed. Disconnect and shutdown."""
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self.attempted_mechs.add(self.mech.name)
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log.info("Authentication failed: %s", stanza['condition'])
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self.xmpp.event("failed_auth", stanza, direct=True)
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self._send_auth()
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return True
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