mirror of
https://github.com/theupdateframework/python-tuf
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258 lines
11 KiB
Python
Executable file
258 lines
11 KiB
Python
Executable file
#!/usr/bin/env python
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"""
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<Program Name>
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test_mix_and_match_attack.py
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<Author>
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Konstantin Andrianov.
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<Started>
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March 27, 2012.
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April 6, 2014.
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Refactored to use the 'unittest' module (test conditions in code, rather
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than verifying text output), use pre-generated repository files, and
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discontinue use of the old repository tools. Modify the previous scenario
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simulated for the mix-and-match attack. -vladimir.v.diaz
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<Copyright>
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See LICENSE for licensing information.
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<Purpose>
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Simulate a mix-and-match attack. In a mix-and-match attack, an attacker is
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able to trick clients into using a combination of metadata that never existed
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together on the repository at the same time.
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Note: There is no difference between 'updates' and 'target' files.
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"""
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# Help with Python 3 compatibility, where the print statement is a function, an
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# implicit relative import is invalid, and the '/' operator performs true
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# division. Example: print 'hello world' raises a 'SyntaxError' exception.
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from __future__ import print_function
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import unicode_literals
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import os
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import tempfile
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import random
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import time
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import shutil
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import json
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import subprocess
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import logging
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import sys
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# 'unittest2' required for testing under Python < 2.7.
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if sys.version_info >= (2, 7):
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import unittest
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else:
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import unittest2 as unittest
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import tuf.formats
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import tuf.util
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import tuf.log
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import tuf.client.updater as updater
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import tuf.repository_tool as repo_tool
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import tuf.unittest_toolbox as unittest_toolbox
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import six
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# The repository tool is imported and logs console messages by default. Disable
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# console log messages generated by this unit test.
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repo_tool.disable_console_log_messages()
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logger = logging.getLogger('tuf.test_mix_and_match_attack')
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class TestMixAndMatchAttack(unittest_toolbox.Modified_TestCase):
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@classmethod
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def setUpClass(cls):
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# setUpClass() is called before any of the test cases are executed.
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# Create a temporary directory to store the repository, metadata, and target
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# files. 'temporary_directory' must be deleted in TearDownModule() so that
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# temporary files are always removed, even when exceptions occur.
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cls.temporary_directory = tempfile.mkdtemp(dir=os.getcwd())
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# Launch a SimpleHTTPServer (serves files in the current directory).
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# Test cases will request metadata and target files that have been
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# pre-generated in 'tuf/tests/repository_data', which will be served by the
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# SimpleHTTPServer launched here. The test cases of this unit test assume
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# the pre-generated metadata files have a specific structure, such
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# as a delegated role 'targets/role1', three target files, five key files,
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# etc.
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cls.SERVER_PORT = random.randint(30000, 45000)
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command = ['python', 'simple_server.py', str(cls.SERVER_PORT)]
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cls.server_process = subprocess.Popen(command, stderr=subprocess.PIPE)
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logger.info('Server process started.')
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logger.info('Server process id: '+str(cls.server_process.pid))
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logger.info('Serving on port: '+str(cls.SERVER_PORT))
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cls.url = 'http://localhost:'+str(cls.SERVER_PORT) + os.path.sep
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# NOTE: Following error is raised if a delay is not applied:
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# <urlopen error [Errno 111] Connection refused>
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time.sleep(.8)
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@classmethod
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def tearDownClass(cls):
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# tearDownModule() is called after all the test cases have run.
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# http://docs.python.org/2/library/unittest.html#class-and-module-fixtures
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# Remove the temporary repository directory, which should contain all the
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# metadata, targets, and key files generated of all the test cases.
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shutil.rmtree(cls.temporary_directory)
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# Kill the SimpleHTTPServer process.
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if cls.server_process.returncode is None:
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logger.info('Server process '+str(cls.server_process.pid)+' terminated.')
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cls.server_process.kill()
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def setUp(self):
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# We are inheriting from custom class.
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unittest_toolbox.Modified_TestCase.setUp(self)
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# Copy the original repository files provided in the test folder so that
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# any modifications made to repository files are restricted to the copies.
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# The 'repository_data' directory is expected to exist in 'tuf/tests/'.
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original_repository_files = os.path.join(os.getcwd(), 'repository_data')
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temporary_repository_root = \
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self.make_temp_directory(directory=self.temporary_directory)
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# The original repository, keystore, and client directories will be copied
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# for each test case.
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original_repository = os.path.join(original_repository_files, 'repository')
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original_client = os.path.join(original_repository_files, 'client')
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original_keystore = os.path.join(original_repository_files, 'keystore')
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# Save references to the often-needed client repository directories.
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# Test cases need these references to access metadata and target files.
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self.repository_directory = \
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os.path.join(temporary_repository_root, 'repository')
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self.client_directory = os.path.join(temporary_repository_root, 'client')
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self.keystore_directory = os.path.join(temporary_repository_root, 'keystore')
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# Copy the original 'repository', 'client', and 'keystore' directories
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# to the temporary repository the test cases can use.
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shutil.copytree(original_repository, self.repository_directory)
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shutil.copytree(original_client, self.client_directory)
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shutil.copytree(original_keystore, self.keystore_directory)
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# Set the url prefix required by the 'tuf/client/updater.py' updater.
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# 'path/to/tmp/repository' -> 'localhost:8001/tmp/repository'.
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repository_basepath = self.repository_directory[len(os.getcwd()):]
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url_prefix = \
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'http://localhost:' + str(self.SERVER_PORT) + repository_basepath
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# Setting 'tuf.conf.repository_directory' with the temporary client
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# directory copied from the original repository files.
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tuf.conf.repository_directory = self.client_directory
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self.repository_mirrors = {'mirror1': {'url_prefix': url_prefix,
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'metadata_path': 'metadata',
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'targets_path': 'targets',
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'confined_target_dirs': ['']}}
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# Create the repository instance. The test cases will use this client
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# updater to refresh metadata, fetch target files, etc.
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self.repository_updater = updater.Updater('test_repository',
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self.repository_mirrors)
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def tearDown(self):
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# Modified_TestCase.tearDown() automatically deletes temporary files and
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# directories that may have been created during each test case.
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unittest_toolbox.Modified_TestCase.tearDown(self)
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def test_with_tuf(self):
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# Scenario:
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# An attacker tries to trick the client into installing files indicated by
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# a previous release of its corresponding metatadata. The outdated metadata
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# is properly named and was previously valid, but is no longer current
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# according to the latest 'snapshot.json' role. Generate a new snapshot of
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# the repository after modifying a target file of 'role1.json'.
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# Backup 'role1.json' (the delegated role to be updated, and then inserted
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# again for the mix-and-match attack.)
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role1_path = os.path.join(self.repository_directory, 'metadata', 'targets',
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'role1.json')
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backup_role1 = os.path.join(self.repository_directory, 'role1.json.backup')
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shutil.copy(role1_path, backup_role1)
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# Backup 'file3.txt', specified by 'role1.json'.
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file3_path = os.path.join(self.repository_directory, 'targets', 'file3.txt')
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shutil.copy(file3_path, file3_path + '.backup')
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# Re-generate the required metadata on the remote repository. The affected
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# metadata must be properly updated and signed with 'repository_tool.py',
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# otherwise the client will reject them as invalid metadata. The resulting
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# metadata should be valid metadata.
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repository = repo_tool.load_repository(self.repository_directory)
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# Load the signing keys so that newly generated metadata is properly signed.
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timestamp_keyfile = os.path.join(self.keystore_directory, 'timestamp_key')
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role1_keyfile = os.path.join(self.keystore_directory, 'delegation_key')
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snapshot_keyfile = os.path.join(self.keystore_directory, 'snapshot_key')
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timestamp_private = \
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repo_tool.import_rsa_privatekey_from_file(timestamp_keyfile, 'password')
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role1_private = \
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repo_tool.import_rsa_privatekey_from_file(role1_keyfile, 'password')
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snapshot_private = \
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repo_tool.import_rsa_privatekey_from_file(snapshot_keyfile, 'password')
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repository.targets('role1').load_signing_key(role1_private)
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repository.snapshot.load_signing_key(snapshot_private)
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repository.timestamp.load_signing_key(timestamp_private)
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# Modify a 'role1.json' target file, and add it to its metadata so that a
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# new version is generated.
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with open(file3_path, 'wt') as file_object:
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file_object.write('This is role2\'s target file.')
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repository.targets('role1').add_target(file3_path)
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repository.write()
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# Move the staged metadata to the "live" metadata.
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shutil.rmtree(os.path.join(self.repository_directory, 'metadata'))
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shutil.copytree(os.path.join(self.repository_directory, 'metadata.staged'),
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os.path.join(self.repository_directory, 'metadata'))
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# Insert the previously valid 'role1.json'. The TUF client should reject it.
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shutil.move(backup_role1, role1_path)
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# Verify that the TUF client detects unexpected metadata (previously valid,
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# but not up-to-date with the latest snapshot of the repository) and refuses
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# to continue the update process.
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# Refresh top-level metadata so that the client is aware of the latest
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# snapshot of the repository.
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self.repository_updater.refresh()
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try:
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self.repository_updater.targets_of_role('targets/role1')
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# Verify that the specific 'tuf.BadVersionNumberError' exception is raised
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# by each mirror.
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except tuf.NoWorkingMirrorError as exception:
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for mirror_url, mirror_error in six.iteritems(exception.mirror_errors):
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url_prefix = self.repository_mirrors['mirror1']['url_prefix']
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url_file = os.path.join(url_prefix, 'metadata', 'targets', 'role1.json')
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# Verify that 'role1.json' is the culprit.
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self.assertEqual(url_file, mirror_url)
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self.assertTrue(isinstance(mirror_error, tuf.BadVersionNumberError))
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else:
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self.fail('TUF did not prevent a mix-and-match attack.')
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if __name__ == '__main__':
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unittest.main()
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