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stbi/Lib/site-packages/pip/_vendor/urllib3/util/ssl_.py

+from __future__ import absolute_import
+import errno
+import warnings
+import hmac
+import sys
+
+from binascii import hexlify, unhexlify
+from hashlib import md5, sha1, sha256
+
+from .url import IPV4_RE, BRACELESS_IPV6_ADDRZ_RE
+from ..exceptions import SSLError, InsecurePlatformWarning, SNIMissingWarning
+from ..packages import six
+
+
+SSLContext = None
+HAS_SNI = False
+IS_PYOPENSSL = False
+IS_SECURETRANSPORT = False
+
+# Maps the length of a digest to a possible hash function producing this digest
+HASHFUNC_MAP = {32: md5, 40: sha1, 64: sha256}
+
+
+def _const_compare_digest_backport(a, b):
+    """
+    Compare two digests of equal length in constant time.
+
+    The digests must be of type str/bytes.
+    Returns True if the digests match, and False otherwise.
+    """
+    result = abs(len(a) - len(b))
+    for l, r in zip(bytearray(a), bytearray(b)):
+        result |= l ^ r
+    return result == 0
+
+
+_const_compare_digest = getattr(hmac, "compare_digest", _const_compare_digest_backport)
+
+try:  # Test for SSL features
+    import ssl
+    from ssl import wrap_socket, CERT_REQUIRED
+    from ssl import HAS_SNI  # Has SNI?
+except ImportError:
+    pass
+
+try:  # Platform-specific: Python 3.6
+    from ssl import PROTOCOL_TLS
+
+    PROTOCOL_SSLv23 = PROTOCOL_TLS
+except ImportError:
+    try:
+        from ssl import PROTOCOL_SSLv23 as PROTOCOL_TLS
+
+        PROTOCOL_SSLv23 = PROTOCOL_TLS
+    except ImportError:
+        PROTOCOL_SSLv23 = PROTOCOL_TLS = 2
+
+
+try:
+    from ssl import OP_NO_SSLv2, OP_NO_SSLv3, OP_NO_COMPRESSION
+except ImportError:
+    OP_NO_SSLv2, OP_NO_SSLv3 = 0x1000000, 0x2000000
+    OP_NO_COMPRESSION = 0x20000
+
+
+# A secure default.
+# Sources for more information on TLS ciphers:
+#
+# - https://wiki.mozilla.org/Security/Server_Side_TLS
+# - https://www.ssllabs.com/projects/best-practices/index.html
+# - https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
+#
+# The general intent is:
+# - prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE),
+# - prefer ECDHE over DHE for better performance,
+# - prefer any AES-GCM and ChaCha20 over any AES-CBC for better performance and
+#   security,
+# - prefer AES-GCM over ChaCha20 because hardware-accelerated AES is common,
+# - disable NULL authentication, MD5 MACs, DSS, and other
+#   insecure ciphers for security reasons.
+# - NOTE: TLS 1.3 cipher suites are managed through a different interface
+#   not exposed by CPython (yet!) and are enabled by default if they're available.
+DEFAULT_CIPHERS = ":".join(
+    [
+        "ECDHE+AESGCM",
+        "ECDHE+CHACHA20",
+        "DHE+AESGCM",
+        "DHE+CHACHA20",
+        "ECDH+AESGCM",
+        "DH+AESGCM",
+        "ECDH+AES",
+        "DH+AES",
+        "RSA+AESGCM",
+        "RSA+AES",
+        "!aNULL",
+        "!eNULL",
+        "!MD5",
+        "!DSS",
+    ]
+)
+
+try:
+    from ssl import SSLContext  # Modern SSL?
+except ImportError:
+
+    class SSLContext(object):  # Platform-specific: Python 2
+        def __init__(self, protocol_version):
+            self.protocol = protocol_version
+            # Use default values from a real SSLContext
+            self.check_hostname = False
+            self.verify_mode = ssl.CERT_NONE
+            self.ca_certs = None
+            self.options = 0
+            self.certfile = None
+            self.keyfile = None
+            self.ciphers = None
+
+        def load_cert_chain(self, certfile, keyfile):
+            self.certfile = certfile
+            self.keyfile = keyfile
+
+        def load_verify_locations(self, cafile=None, capath=None):
+            self.ca_certs = cafile
+
+            if capath is not None:
+                raise SSLError("CA directories not supported in older Pythons")
+
+        def set_ciphers(self, cipher_suite):
+            self.ciphers = cipher_suite
+
+        def wrap_socket(self, socket, server_hostname=None, server_side=False):
+            warnings.warn(
+                "A true SSLContext object is not available. This prevents "
+                "urllib3 from configuring SSL appropriately and may cause "
+                "certain SSL connections to fail. You can upgrade to a newer "
+                "version of Python to solve this. For more information, see "
+                "https://urllib3.readthedocs.io/en/latest/advanced-usage.html"
+                "#ssl-warnings",
+                InsecurePlatformWarning,
+            )
+            kwargs = {
+                "keyfile": self.keyfile,
+                "certfile": self.certfile,
+                "ca_certs": self.ca_certs,
+                "cert_reqs": self.verify_mode,
+                "ssl_version": self.protocol,
+                "server_side": server_side,
+            }
+            return wrap_socket(socket, ciphers=self.ciphers, **kwargs)
+
+
+def assert_fingerprint(cert, fingerprint):
+    """
+    Checks if given fingerprint matches the supplied certificate.
+
+    :param cert:
+        Certificate as bytes object.
+    :param fingerprint:
+        Fingerprint as string of hexdigits, can be interspersed by colons.
+    """
+
+    fingerprint = fingerprint.replace(":", "").lower()
+    digest_length = len(fingerprint)
+    hashfunc = HASHFUNC_MAP.get(digest_length)
+    if not hashfunc:
+        raise SSLError("Fingerprint of invalid length: {0}".format(fingerprint))
+
+    # We need encode() here for py32; works on py2 and p33.
+    fingerprint_bytes = unhexlify(fingerprint.encode())
+
+    cert_digest = hashfunc(cert).digest()
+
+    if not _const_compare_digest(cert_digest, fingerprint_bytes):
+        raise SSLError(
+            'Fingerprints did not match. Expected "{0}", got "{1}".'.format(
+                fingerprint, hexlify(cert_digest)
+            )
+        )
+
+
+def resolve_cert_reqs(candidate):
+    """
+    Resolves the argument to a numeric constant, which can be passed to
+    the wrap_socket function/method from the ssl module.
+    Defaults to :data:`ssl.CERT_REQUIRED`.
+    If given a string it is assumed to be the name of the constant in the
+    :mod:`ssl` module or its abbreviation.
+    (So you can specify `REQUIRED` instead of `CERT_REQUIRED`.
+    If it's neither `None` nor a string we assume it is already the numeric
+    constant which can directly be passed to wrap_socket.
+    """
+    if candidate is None:
+        return CERT_REQUIRED
+
+    if isinstance(candidate, str):
+        res = getattr(ssl, candidate, None)
+        if res is None:
+            res = getattr(ssl, "CERT_" + candidate)
+        return res
+
+    return candidate
+
+
+def resolve_ssl_version(candidate):
+    """
+    like resolve_cert_reqs
+    """
+    if candidate is None:
+        return PROTOCOL_TLS
+
+    if isinstance(candidate, str):
+        res = getattr(ssl, candidate, None)
+        if res is None:
+            res = getattr(ssl, "PROTOCOL_" + candidate)
+        return res
+
+    return candidate
+
+
+def create_urllib3_context(
+    ssl_version=None, cert_reqs=None, options=None, ciphers=None
+):
+    """All arguments have the same meaning as ``ssl_wrap_socket``.
+
+    By default, this function does a lot of the same work that
+    ``ssl.create_default_context`` does on Python 3.4+. It:
+
+    - Disables SSLv2, SSLv3, and compression
+    - Sets a restricted set of server ciphers
+
+    If you wish to enable SSLv3, you can do::
+
+        from pip._vendor.urllib3.util import ssl_
+        context = ssl_.create_urllib3_context()
+        context.options &= ~ssl_.OP_NO_SSLv3
+
+    You can do the same to enable compression (substituting ``COMPRESSION``
+    for ``SSLv3`` in the last line above).
+
+    :param ssl_version:
+        The desired protocol version to use. This will default to
+        PROTOCOL_SSLv23 which will negotiate the highest protocol that both
+        the server and your installation of OpenSSL support.
+    :param cert_reqs:
+        Whether to require the certificate verification. This defaults to
+        ``ssl.CERT_REQUIRED``.
+    :param options:
+        Specific OpenSSL options. These default to ``ssl.OP_NO_SSLv2``,
+        ``ssl.OP_NO_SSLv3``, ``ssl.OP_NO_COMPRESSION``.
+    :param ciphers:
+        Which cipher suites to allow the server to select.
+    :returns:
+        Constructed SSLContext object with specified options
+    :rtype: SSLContext
+    """
+    context = SSLContext(ssl_version or PROTOCOL_TLS)
+
+    context.set_ciphers(ciphers or DEFAULT_CIPHERS)
+
+    # Setting the default here, as we may have no ssl module on import
+    cert_reqs = ssl.CERT_REQUIRED if cert_reqs is None else cert_reqs
+
+    if options is None:
+        options = 0
+        # SSLv2 is easily broken and is considered harmful and dangerous
+        options |= OP_NO_SSLv2
+        # SSLv3 has several problems and is now dangerous
+        options |= OP_NO_SSLv3
+        # Disable compression to prevent CRIME attacks for OpenSSL 1.0+
+        # (issue #309)
+        options |= OP_NO_COMPRESSION
+
+    context.options |= options
+
+    # Enable post-handshake authentication for TLS 1.3, see GH #1634. PHA is
+    # necessary for conditional client cert authentication with TLS 1.3.
+    # The attribute is None for OpenSSL <= 1.1.0 or does not exist in older
+    # versions of Python.  We only enable on Python 3.7.4+ or if certificate
+    # verification is enabled to work around Python issue #37428
+    # See: https://bugs.python.org/issue37428
+    if (cert_reqs == ssl.CERT_REQUIRED or sys.version_info >= (3, 7, 4)) and getattr(
+        context, "post_handshake_auth", None
+    ) is not None:
+        context.post_handshake_auth = True
+
+    context.verify_mode = cert_reqs
+    if (
+        getattr(context, "check_hostname", None) is not None
+    ):  # Platform-specific: Python 3.2
+        # We do our own verification, including fingerprints and alternative
+        # hostnames. So disable it here
+        context.check_hostname = False
+    return context
+
+
+def ssl_wrap_socket(
+    sock,
+    keyfile=None,
+    certfile=None,
+    cert_reqs=None,
+    ca_certs=None,
+    server_hostname=None,
+    ssl_version=None,
+    ciphers=None,
+    ssl_context=None,
+    ca_cert_dir=None,
+    key_password=None,
+):
+    """
+    All arguments except for server_hostname, ssl_context, and ca_cert_dir have
+    the same meaning as they do when using :func:`ssl.wrap_socket`.
+
+    :param server_hostname:
+        When SNI is supported, the expected hostname of the certificate
+    :param ssl_context:
+        A pre-made :class:`SSLContext` object. If none is provided, one will
+        be created using :func:`create_urllib3_context`.
+    :param ciphers:
+        A string of ciphers we wish the client to support.
+    :param ca_cert_dir:
+        A directory containing CA certificates in multiple separate files, as
+        supported by OpenSSL's -CApath flag or the capath argument to
+        SSLContext.load_verify_locations().
+    :param key_password:
+        Optional password if the keyfile is encrypted.
+    """
+    context = ssl_context
+    if context is None:
+        # Note: This branch of code and all the variables in it are no longer
+        # used by urllib3 itself. We should consider deprecating and removing
+        # this code.
+        context = create_urllib3_context(ssl_version, cert_reqs, ciphers=ciphers)
+
+    if ca_certs or ca_cert_dir:
+        try:
+            context.load_verify_locations(ca_certs, ca_cert_dir)
+        except IOError as e:  # Platform-specific: Python 2.7
+            raise SSLError(e)
+        # Py33 raises FileNotFoundError which subclasses OSError
+        # These are not equivalent unless we check the errno attribute
+        except OSError as e:  # Platform-specific: Python 3.3 and beyond
+            if e.errno == errno.ENOENT:
+                raise SSLError(e)
+            raise
+
+    elif ssl_context is None and hasattr(context, "load_default_certs"):
+        # try to load OS default certs; works well on Windows (require Python3.4+)
+        context.load_default_certs()
+
+    # Attempt to detect if we get the goofy behavior of the
+    # keyfile being encrypted and OpenSSL asking for the
+    # passphrase via the terminal and instead error out.
+    if keyfile and key_password is None and _is_key_file_encrypted(keyfile):
+        raise SSLError("Client private key is encrypted, password is required")
+
+    if certfile:
+        if key_password is None:
+            context.load_cert_chain(certfile, keyfile)
+        else:
+            context.load_cert_chain(certfile, keyfile, key_password)
+
+    # If we detect server_hostname is an IP address then the SNI
+    # extension should not be used according to RFC3546 Section 3.1
+    # We shouldn't warn the user if SNI isn't available but we would
+    # not be using SNI anyways due to IP address for server_hostname.
+    if (
+        server_hostname is not None and not is_ipaddress(server_hostname)
+    ) or IS_SECURETRANSPORT:
+        if HAS_SNI and server_hostname is not None:
+            return context.wrap_socket(sock, server_hostname=server_hostname)
+
+        warnings.warn(
+            "An HTTPS request has been made, but the SNI (Server Name "
+            "Indication) extension to TLS is not available on this platform. "
+            "This may cause the server to present an incorrect TLS "
+            "certificate, which can cause validation failures. You can upgrade to "
+            "a newer version of Python to solve this. For more information, see "
+            "https://urllib3.readthedocs.io/en/latest/advanced-usage.html"
+            "#ssl-warnings",
+            SNIMissingWarning,
+        )
+
+    return context.wrap_socket(sock)
+
+
+def is_ipaddress(hostname):
+    """Detects whether the hostname given is an IPv4 or IPv6 address.
+    Also detects IPv6 addresses with Zone IDs.
+
+    :param str hostname: Hostname to examine.
+    :return: True if the hostname is an IP address, False otherwise.
+    """
+    if not six.PY2 and isinstance(hostname, bytes):
+        # IDN A-label bytes are ASCII compatible.
+        hostname = hostname.decode("ascii")
+    return bool(IPV4_RE.match(hostname) or BRACELESS_IPV6_ADDRZ_RE.match(hostname))
+
+
+def _is_key_file_encrypted(key_file):
+    """Detects if a key file is encrypted or not."""
+    with open(key_file, "r") as f:
+        for line in f:
+            # Look for Proc-Type: 4,ENCRYPTED
+            if "ENCRYPTED" in line:
+                return True
+
+    return False