520 lines
17 KiB
Python
520 lines
17 KiB
Python
"""
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TLS with SNI_-support for Python 2. Follow these instructions if you would
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like to verify TLS certificates in Python 2. Note, the default libraries do
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*not* do certificate checking; you need to do additional work to validate
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certificates yourself.
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This needs the following packages installed:
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* `pyOpenSSL`_ (tested with 16.0.0)
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* `cryptography`_ (minimum 1.3.4, from pyopenssl)
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* `idna`_ (minimum 2.0, from cryptography)
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However, pyopenssl depends on cryptography, which depends on idna, so while we
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use all three directly here we end up having relatively few packages required.
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You can install them with the following command:
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.. code-block:: bash
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$ python -m pip install pyopenssl cryptography idna
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To activate certificate checking, call
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:func:`~urllib3.contrib.pyopenssl.inject_into_urllib3` from your Python code
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before you begin making HTTP requests. This can be done in a ``sitecustomize``
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module, or at any other time before your application begins using ``urllib3``,
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like this:
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.. code-block:: python
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try:
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import urllib3.contrib.pyopenssl
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urllib3.contrib.pyopenssl.inject_into_urllib3()
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except ImportError:
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pass
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Now you can use :mod:`urllib3` as you normally would, and it will support SNI
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when the required modules are installed.
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Activating this module also has the positive side effect of disabling SSL/TLS
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compression in Python 2 (see `CRIME attack`_).
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.. _sni: https://en.wikipedia.org/wiki/Server_Name_Indication
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.. _crime attack: https://en.wikipedia.org/wiki/CRIME_(security_exploit)
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.. _pyopenssl: https://www.pyopenssl.org
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.. _cryptography: https://cryptography.io
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.. _idna: https://github.com/kjd/idna
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"""
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from __future__ import absolute_import
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import OpenSSL.SSL
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from cryptography import x509
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from cryptography.hazmat.backends.openssl import backend as openssl_backend
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from cryptography.hazmat.backends.openssl.x509 import _Certificate
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try:
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from cryptography.x509 import UnsupportedExtension
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except ImportError:
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# UnsupportedExtension is gone in cryptography >= 2.1.0
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class UnsupportedExtension(Exception):
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pass
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from io import BytesIO
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from socket import error as SocketError
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from socket import timeout
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try: # Platform-specific: Python 2
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from socket import _fileobject
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except ImportError: # Platform-specific: Python 3
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_fileobject = None
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from ..packages.backports.makefile import backport_makefile
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import logging
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import ssl
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import sys
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import warnings
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from .. import util
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from ..packages import six
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from ..util.ssl_ import PROTOCOL_TLS_CLIENT
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warnings.warn(
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"'urllib3.contrib.pyopenssl' module is deprecated and will be removed "
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"in a future release of urllib3 2.x. Read more in this issue: "
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"https://github.com/urllib3/urllib3/issues/2680",
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category=DeprecationWarning,
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stacklevel=2,
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)
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__all__ = ["inject_into_urllib3", "extract_from_urllib3"]
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# SNI always works.
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HAS_SNI = True
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# Map from urllib3 to PyOpenSSL compatible parameter-values.
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_openssl_versions = {
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util.PROTOCOL_TLS: OpenSSL.SSL.SSLv23_METHOD,
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PROTOCOL_TLS_CLIENT: OpenSSL.SSL.SSLv23_METHOD,
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ssl.PROTOCOL_TLSv1: OpenSSL.SSL.TLSv1_METHOD,
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}
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if hasattr(ssl, "PROTOCOL_SSLv3") and hasattr(OpenSSL.SSL, "SSLv3_METHOD"):
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_openssl_versions[ssl.PROTOCOL_SSLv3] = OpenSSL.SSL.SSLv3_METHOD
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if hasattr(ssl, "PROTOCOL_TLSv1_1") and hasattr(OpenSSL.SSL, "TLSv1_1_METHOD"):
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_openssl_versions[ssl.PROTOCOL_TLSv1_1] = OpenSSL.SSL.TLSv1_1_METHOD
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if hasattr(ssl, "PROTOCOL_TLSv1_2") and hasattr(OpenSSL.SSL, "TLSv1_2_METHOD"):
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_openssl_versions[ssl.PROTOCOL_TLSv1_2] = OpenSSL.SSL.TLSv1_2_METHOD
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_stdlib_to_openssl_verify = {
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ssl.CERT_NONE: OpenSSL.SSL.VERIFY_NONE,
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ssl.CERT_OPTIONAL: OpenSSL.SSL.VERIFY_PEER,
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ssl.CERT_REQUIRED: OpenSSL.SSL.VERIFY_PEER
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+ OpenSSL.SSL.VERIFY_FAIL_IF_NO_PEER_CERT,
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}
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_openssl_to_stdlib_verify = dict((v, k) for k, v in _stdlib_to_openssl_verify.items())
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# OpenSSL will only write 16K at a time
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SSL_WRITE_BLOCKSIZE = 16384
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orig_util_HAS_SNI = util.HAS_SNI
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orig_util_SSLContext = util.ssl_.SSLContext
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log = logging.getLogger(__name__)
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def inject_into_urllib3():
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"Monkey-patch urllib3 with PyOpenSSL-backed SSL-support."
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_validate_dependencies_met()
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util.SSLContext = PyOpenSSLContext
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util.ssl_.SSLContext = PyOpenSSLContext
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util.HAS_SNI = HAS_SNI
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util.ssl_.HAS_SNI = HAS_SNI
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util.IS_PYOPENSSL = True
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util.ssl_.IS_PYOPENSSL = True
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def extract_from_urllib3():
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"Undo monkey-patching by :func:`inject_into_urllib3`."
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util.SSLContext = orig_util_SSLContext
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util.ssl_.SSLContext = orig_util_SSLContext
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util.HAS_SNI = orig_util_HAS_SNI
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util.ssl_.HAS_SNI = orig_util_HAS_SNI
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util.IS_PYOPENSSL = False
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util.ssl_.IS_PYOPENSSL = False
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def _validate_dependencies_met():
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"""
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Verifies that PyOpenSSL's package-level dependencies have been met.
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Throws `ImportError` if they are not met.
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"""
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# Method added in `cryptography==1.1`; not available in older versions
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from cryptography.x509.extensions import Extensions
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if getattr(Extensions, "get_extension_for_class", None) is None:
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raise ImportError(
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"'cryptography' module missing required functionality. "
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"Try upgrading to v1.3.4 or newer."
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)
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# pyOpenSSL 0.14 and above use cryptography for OpenSSL bindings. The _x509
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# attribute is only present on those versions.
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from OpenSSL.crypto import X509
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x509 = X509()
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if getattr(x509, "_x509", None) is None:
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raise ImportError(
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"'pyOpenSSL' module missing required functionality. "
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"Try upgrading to v0.14 or newer."
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)
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def _dnsname_to_stdlib(name):
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"""
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Converts a dNSName SubjectAlternativeName field to the form used by the
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standard library on the given Python version.
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Cryptography produces a dNSName as a unicode string that was idna-decoded
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from ASCII bytes. We need to idna-encode that string to get it back, and
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then on Python 3 we also need to convert to unicode via UTF-8 (the stdlib
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uses PyUnicode_FromStringAndSize on it, which decodes via UTF-8).
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If the name cannot be idna-encoded then we return None signalling that
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the name given should be skipped.
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"""
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def idna_encode(name):
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"""
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Borrowed wholesale from the Python Cryptography Project. It turns out
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that we can't just safely call `idna.encode`: it can explode for
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wildcard names. This avoids that problem.
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"""
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import idna
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try:
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for prefix in [u"*.", u"."]:
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if name.startswith(prefix):
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name = name[len(prefix) :]
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return prefix.encode("ascii") + idna.encode(name)
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return idna.encode(name)
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except idna.core.IDNAError:
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return None
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# Don't send IPv6 addresses through the IDNA encoder.
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if ":" in name:
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return name
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name = idna_encode(name)
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if name is None:
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return None
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elif sys.version_info >= (3, 0):
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name = name.decode("utf-8")
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return name
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def get_subj_alt_name(peer_cert):
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"""
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Given an PyOpenSSL certificate, provides all the subject alternative names.
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"""
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# Pass the cert to cryptography, which has much better APIs for this.
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if hasattr(peer_cert, "to_cryptography"):
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cert = peer_cert.to_cryptography()
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else:
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# This is technically using private APIs, but should work across all
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# relevant versions before PyOpenSSL got a proper API for this.
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cert = _Certificate(openssl_backend, peer_cert._x509)
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# We want to find the SAN extension. Ask Cryptography to locate it (it's
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# faster than looping in Python)
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try:
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ext = cert.extensions.get_extension_for_class(x509.SubjectAlternativeName).value
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except x509.ExtensionNotFound:
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# No such extension, return the empty list.
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return []
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except (
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x509.DuplicateExtension,
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UnsupportedExtension,
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x509.UnsupportedGeneralNameType,
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UnicodeError,
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) as e:
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# A problem has been found with the quality of the certificate. Assume
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# no SAN field is present.
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log.warning(
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"A problem was encountered with the certificate that prevented "
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"urllib3 from finding the SubjectAlternativeName field. This can "
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"affect certificate validation. The error was %s",
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e,
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)
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return []
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# We want to return dNSName and iPAddress fields. We need to cast the IPs
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# back to strings because the match_hostname function wants them as
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# strings.
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# Sadly the DNS names need to be idna encoded and then, on Python 3, UTF-8
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# decoded. This is pretty frustrating, but that's what the standard library
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# does with certificates, and so we need to attempt to do the same.
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# We also want to skip over names which cannot be idna encoded.
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names = [
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("DNS", name)
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for name in map(_dnsname_to_stdlib, ext.get_values_for_type(x509.DNSName))
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if name is not None
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]
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names.extend(
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("IP Address", str(name)) for name in ext.get_values_for_type(x509.IPAddress)
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)
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return names
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class WrappedSocket(object):
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"""API-compatibility wrapper for Python OpenSSL's Connection-class.
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Note: _makefile_refs, _drop() and _reuse() are needed for the garbage
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collector of pypy.
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"""
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def __init__(self, connection, socket, suppress_ragged_eofs=True):
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self.connection = connection
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self.socket = socket
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self.suppress_ragged_eofs = suppress_ragged_eofs
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self._makefile_refs = 0
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self._closed = False
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def fileno(self):
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return self.socket.fileno()
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# Copy-pasted from Python 3.5 source code
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def _decref_socketios(self):
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if self._makefile_refs > 0:
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self._makefile_refs -= 1
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if self._closed:
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self.close()
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def recv(self, *args, **kwargs):
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try:
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data = self.connection.recv(*args, **kwargs)
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except OpenSSL.SSL.SysCallError as e:
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if self.suppress_ragged_eofs and e.args == (-1, "Unexpected EOF"):
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return b""
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else:
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raise SocketError(str(e))
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except OpenSSL.SSL.ZeroReturnError:
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if self.connection.get_shutdown() == OpenSSL.SSL.RECEIVED_SHUTDOWN:
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return b""
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else:
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raise
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except OpenSSL.SSL.WantReadError:
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if not util.wait_for_read(self.socket, self.socket.gettimeout()):
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raise timeout("The read operation timed out")
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else:
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return self.recv(*args, **kwargs)
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# TLS 1.3 post-handshake authentication
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except OpenSSL.SSL.Error as e:
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raise ssl.SSLError("read error: %r" % e)
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else:
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return data
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def recv_into(self, *args, **kwargs):
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try:
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return self.connection.recv_into(*args, **kwargs)
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except OpenSSL.SSL.SysCallError as e:
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if self.suppress_ragged_eofs and e.args == (-1, "Unexpected EOF"):
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return 0
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else:
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raise SocketError(str(e))
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except OpenSSL.SSL.ZeroReturnError:
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if self.connection.get_shutdown() == OpenSSL.SSL.RECEIVED_SHUTDOWN:
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return 0
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else:
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raise
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except OpenSSL.SSL.WantReadError:
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if not util.wait_for_read(self.socket, self.socket.gettimeout()):
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raise timeout("The read operation timed out")
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else:
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return self.recv_into(*args, **kwargs)
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# TLS 1.3 post-handshake authentication
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except OpenSSL.SSL.Error as e:
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raise ssl.SSLError("read error: %r" % e)
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def settimeout(self, timeout):
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return self.socket.settimeout(timeout)
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def _send_until_done(self, data):
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while True:
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try:
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return self.connection.send(data)
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except OpenSSL.SSL.WantWriteError:
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if not util.wait_for_write(self.socket, self.socket.gettimeout()):
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raise timeout()
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continue
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except OpenSSL.SSL.SysCallError as e:
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raise SocketError(str(e))
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def sendall(self, data):
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total_sent = 0
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while total_sent < len(data):
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sent = self._send_until_done(
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data[total_sent : total_sent + SSL_WRITE_BLOCKSIZE]
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)
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total_sent += sent
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def shutdown(self):
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# FIXME rethrow compatible exceptions should we ever use this
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self.connection.shutdown()
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def close(self):
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if self._makefile_refs < 1:
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try:
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self._closed = True
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return self.connection.close()
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except OpenSSL.SSL.Error:
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return
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else:
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self._makefile_refs -= 1
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def getpeercert(self, binary_form=False):
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x509 = self.connection.get_peer_certificate()
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if not x509:
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return x509
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if binary_form:
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return OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_ASN1, x509)
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return {
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"subject": ((("commonName", x509.get_subject().CN),),),
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"subjectAltName": get_subj_alt_name(x509),
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}
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def version(self):
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return self.connection.get_protocol_version_name()
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def _reuse(self):
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self._makefile_refs += 1
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def _drop(self):
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if self._makefile_refs < 1:
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self.close()
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|
else:
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self._makefile_refs -= 1
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|
|
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if _fileobject: # Platform-specific: Python 2
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def makefile(self, mode, bufsize=-1):
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self._makefile_refs += 1
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return _fileobject(self, mode, bufsize, close=True)
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else: # Platform-specific: Python 3
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makefile = backport_makefile
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WrappedSocket.makefile = makefile
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|
|
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class PyOpenSSLContext(object):
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"""
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I am a wrapper class for the PyOpenSSL ``Context`` object. I am responsible
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for translating the interface of the standard library ``SSLContext`` object
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to calls into PyOpenSSL.
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"""
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def __init__(self, protocol):
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self.protocol = _openssl_versions[protocol]
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self._ctx = OpenSSL.SSL.Context(self.protocol)
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self._options = 0
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self.check_hostname = False
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|
|
@property
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|
def options(self):
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return self._options
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|
|
@options.setter
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|
def options(self, value):
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|
self._options = value
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self._ctx.set_options(value)
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|
|
@property
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def verify_mode(self):
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|
return _openssl_to_stdlib_verify[self._ctx.get_verify_mode()]
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|
|
|
@verify_mode.setter
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|
def verify_mode(self, value):
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|
self._ctx.set_verify(_stdlib_to_openssl_verify[value], _verify_callback)
|
|
|
|
def set_default_verify_paths(self):
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|
self._ctx.set_default_verify_paths()
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|
|
|
def set_ciphers(self, ciphers):
|
|
if isinstance(ciphers, six.text_type):
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|
ciphers = ciphers.encode("utf-8")
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|
self._ctx.set_cipher_list(ciphers)
|
|
|
|
def load_verify_locations(self, cafile=None, capath=None, cadata=None):
|
|
if cafile is not None:
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|
cafile = cafile.encode("utf-8")
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|
if capath is not None:
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|
capath = capath.encode("utf-8")
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|
try:
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|
self._ctx.load_verify_locations(cafile, capath)
|
|
if cadata is not None:
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|
self._ctx.load_verify_locations(BytesIO(cadata))
|
|
except OpenSSL.SSL.Error as e:
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|
raise ssl.SSLError("unable to load trusted certificates: %r" % e)
|
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|
|
def load_cert_chain(self, certfile, keyfile=None, password=None):
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self._ctx.use_certificate_chain_file(certfile)
|
|
if password is not None:
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|
if not isinstance(password, six.binary_type):
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password = password.encode("utf-8")
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self._ctx.set_passwd_cb(lambda *_: password)
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self._ctx.use_privatekey_file(keyfile or certfile)
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def set_alpn_protocols(self, protocols):
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protocols = [six.ensure_binary(p) for p in protocols]
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return self._ctx.set_alpn_protos(protocols)
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|
def wrap_socket(
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|
self,
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sock,
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server_side=False,
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do_handshake_on_connect=True,
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|
suppress_ragged_eofs=True,
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|
server_hostname=None,
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):
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|
cnx = OpenSSL.SSL.Connection(self._ctx, sock)
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|
|
if isinstance(server_hostname, six.text_type): # Platform-specific: Python 3
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|
server_hostname = server_hostname.encode("utf-8")
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|
if server_hostname is not None:
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|
cnx.set_tlsext_host_name(server_hostname)
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|
cnx.set_connect_state()
|
|
|
|
while True:
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|
try:
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|
cnx.do_handshake()
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|
except OpenSSL.SSL.WantReadError:
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|
if not util.wait_for_read(sock, sock.gettimeout()):
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|
raise timeout("select timed out")
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|
continue
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|
except OpenSSL.SSL.Error as e:
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|
raise ssl.SSLError("bad handshake: %r" % e)
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|
break
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|
return WrappedSocket(cnx, sock)
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|
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def _verify_callback(cnx, x509, err_no, err_depth, return_code):
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return err_no == 0
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