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#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
#
from logging import getLogger
log = getLogger("qpid.saslmech")
def get_sasl_mechanism(mechanismNames, username, password, namespace="qpid.saslmech", sasl_options=None):
"""Given a list of SASL mechanism names, dynamically loads a SASL implementation
from namespace qpid.sasl.mech respecting a mechanism priority"""
log.debug("Supported mechanism : %s", mechanismNames)
instances = []
for mechanismName in mechanismNames:
convertedName = mechanismName.replace("-","_")
canonicalName = "%s.%s.%s" % (namespace, convertedName.lower(), convertedName)
try:
log.debug("Checking for SASL implementation %s for mechanism %s", canonicalName, mechanismName)
clazz = _get_class(canonicalName)
log.debug("Found SASL implementation")
instance = clazz(username, password, mechanismName, sasl_options)
if (instance.prerequisitesOk()):
instances.append(instance)
else:
log.debug("SASL mechanism %s unavailable as the prerequistes for this mechanism have not been met", mechanismName)
except (ImportError, AttributeError), e:
# Unknown mechanism - this is normal if the server supports mechanism that the client does not
log.debug("Could not load implementation for %s", canonicalName)
pass
if instances:
instances.sort(key=lambda x : x.priority(), reverse=True)
sasl = instances[0]
log.debug("Selected SASL mechanism %s", sasl.mechanismName())
return sasl
else:
return None
def _get_class( kls ):
parts = kls.split('.')
module = ".".join(parts[:-1])
m = __import__( module )
for comp in parts[1:]:
m = getattr(m, comp)
return m
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