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from os.path import dirname, realpath, join
import builtins
import os
from pathlib import Path
import struct
import sys
import unittest
import pytest
from paramiko.ssh_gss import GSS_AUTH_AVAILABLE
from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import padding, rsa
tests_dir = dirname(realpath(__file__))
def _support(filename):
base = Path(tests_dir)
top = base / filename
deeper = base / "_support" / filename
return str(deeper if deeper.exists() else top)
def _config(name):
return join(tests_dir, "configs", name)
needs_gssapi = pytest.mark.skipif(
not GSS_AUTH_AVAILABLE, reason="No GSSAPI to test"
)
def needs_builtin(name):
"""
Skip decorated test if builtin name does not exist.
"""
reason = "Test requires a builtin '{}'".format(name)
return pytest.mark.skipif(not hasattr(builtins, name), reason=reason)
slow = pytest.mark.slow
# GSSAPI / Kerberos related tests need a working Kerberos environment.
# The class `KerberosTestCase` provides such an environment or skips all tests.
# There are 3 distinct cases:
#
# - A Kerberos environment has already been created and the environment
# contains the required information.
#
# - We can use the package 'k5test' to setup an working kerberos environment on
# the fly.
#
# - We skip all tests.
#
# ToDo: add a Windows specific implementation?
if (
os.environ.get("K5TEST_USER_PRINC", None)
and os.environ.get("K5TEST_HOSTNAME", None)
and os.environ.get("KRB5_KTNAME", None)
): # add other vars as needed
# The environment provides the required information
class DummyK5Realm:
def __init__(self):
for k in os.environ:
if not k.startswith("K5TEST_"):
continue
setattr(self, k[7:].lower(), os.environ[k])
self.env = {}
class KerberosTestCase(unittest.TestCase):
@classmethod
def setUpClass(cls):
cls.realm = DummyK5Realm()
@classmethod
def tearDownClass(cls):
del cls.realm
else:
try:
# Try to setup a kerberos environment
from k5test import KerberosTestCase
except Exception:
# Use a dummy, that skips all tests
class KerberosTestCase(unittest.TestCase):
@classmethod
def setUpClass(cls):
raise unittest.SkipTest(
"Missing extension package k5test. "
'Please run "pip install k5test" '
"to install it."
)
def update_env(testcase, mapping, env=os.environ):
"""Modify os.environ during a test case and restore during cleanup."""
saved_env = env.copy()
def replace(target, source):
target.update(source)
for k in list(target):
if k not in source:
target.pop(k, None)
testcase.addCleanup(replace, env, saved_env)
env.update(mapping)
return testcase
def k5shell(args=None):
"""Create a shell with an kerberos environment
This can be used to debug paramiko or to test the old GSSAPI.
To test a different GSSAPI, simply activate a suitable venv
within the shell.
"""
import k5test
import atexit
import subprocess
k5 = k5test.K5Realm()
atexit.register(k5.stop)
os.environ.update(k5.env)
for n in ("realm", "user_princ", "hostname"):
os.environ["K5TEST_" + n.upper()] = getattr(k5, n)
if not args:
args = sys.argv[1:]
if not args:
args = [os.environ.get("SHELL", "bash")]
sys.exit(subprocess.call(args))
def is_low_entropy():
"""
Attempts to detect whether running interpreter is low-entropy.
"low-entropy" is defined as being in 32-bit mode and with the hash seed set
to zero.
"""
is_32bit = struct.calcsize("P") == 32 / 8
# I don't see a way to tell internally if the hash seed was set this
# way, but env should be plenty sufficient, this is only for testing.
return is_32bit and os.environ.get("PYTHONHASHSEED", None) == "0"
def sha1_signing_unsupported():
"""
This is used to skip tests in environments where SHA-1 signing is
not supported by the backend.
"""
private_key = rsa.generate_private_key(
public_exponent=65537, key_size=2048, backend=default_backend()
)
message = b"Some dummy text"
try:
private_key.sign(
message,
padding.PSS(
mgf=padding.MGF1(hashes.SHA1()),
salt_length=padding.PSS.MAX_LENGTH,
),
hashes.SHA1(),
)
return False
except UnsupportedAlgorithm as e:
return e._reason is _Reasons.UNSUPPORTED_HASH
requires_sha1_signing = unittest.skipIf(
sha1_signing_unsupported(), "SHA-1 signing not supported"
)
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