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Diffstat (limited to 'requests/packages/urllib3/util/ssl_.py')
| -rw-r--r-- | requests/packages/urllib3/util/ssl_.py | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/requests/packages/urllib3/util/ssl_.py b/requests/packages/urllib3/util/ssl_.py new file mode 100644 index 0000000..b846d42 --- /dev/null +++ b/requests/packages/urllib3/util/ssl_.py @@ -0,0 +1,280 @@ +from binascii import hexlify, unhexlify +from hashlib import md5, sha1, sha256 + +from ..exceptions import SSLError, InsecurePlatformWarning + + +SSLContext = None +HAS_SNI = False +create_default_context = None + +import errno +import warnings + +try: # Test for SSL features + import ssl + from ssl import wrap_socket, CERT_NONE, PROTOCOL_SSLv23 + from ssl import HAS_SNI # Has SNI? +except ImportError: + pass + + +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 over any AES-CBC for better performance and security, +# - use 3DES as fallback which is secure but slow, +# - disable NULL authentication, MD5 MACs and DSS for security reasons. +DEFAULT_CIPHERS = ( + 'ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+HIGH:' + 'DH+HIGH:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+HIGH:RSA+3DES:!aNULL:' + '!eNULL:!MD5' +) + +try: + from ssl import SSLContext # Modern SSL? +except ImportError: + import sys + + class SSLContext(object): # Platform-specific: Python 2 & 3.1 + supports_set_ciphers = ((2, 7) <= sys.version_info < (3,) or + (3, 2) <= sys.version_info) + + 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, location): + self.ca_certs = location + + def set_ciphers(self, cipher_suite): + if not self.supports_set_ciphers: + raise TypeError( + 'Your version of Python does not support setting ' + 'a custom cipher suite. Please upgrade to Python ' + '2.7, 3.2, or later if you need this functionality.' + ) + self.ciphers = cipher_suite + + def wrap_socket(self, socket, server_hostname=None): + warnings.warn( + 'A true SSLContext object is not available. This prevents ' + 'urllib3 from configuring SSL appropriately and may cause ' + 'certain SSL connections to fail. For more information, see ' + 'https://urllib3.readthedocs.org/en/latest/security.html' + '#insecureplatformwarning.', + InsecurePlatformWarning + ) + kwargs = { + 'keyfile': self.keyfile, + 'certfile': self.certfile, + 'ca_certs': self.ca_certs, + 'cert_reqs': self.verify_mode, + 'ssl_version': self.protocol, + } + if self.supports_set_ciphers: # Platform-specific: Python 2.7+ + return wrap_socket(socket, ciphers=self.ciphers, **kwargs) + else: # Platform-specific: Python 2.6 + return wrap_socket(socket, **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. + """ + + # Maps the length of a digest to a possible hash function producing + # this digest. + hashfunc_map = { + 16: md5, + 20: sha1, + 32: sha256, + } + + fingerprint = fingerprint.replace(':', '').lower() + digest_length, odd = divmod(len(fingerprint), 2) + + if odd or digest_length not in hashfunc_map: + raise SSLError('Fingerprint is of invalid length.') + + # We need encode() here for py32; works on py2 and p33. + fingerprint_bytes = unhexlify(fingerprint.encode()) + + hashfunc = hashfunc_map[digest_length] + + cert_digest = hashfunc(cert).digest() + + if not cert_digest == fingerprint_bytes: + raise SSLError('Fingerprints did not match. Expected "{0}", got "{1}".' + .format(hexlify(fingerprint_bytes), + 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_NONE`. + If given a string it is assumed to be the name of the constant in the + :mod:`ssl` module or its abbrevation. + (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_NONE + + 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_SSLv23 + + 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 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 ssl.PROTOCOL_SSLv23) + + # 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 + + if getattr(context, 'supports_set_ciphers', True): # Platform-specific: Python 2.6 + context.set_ciphers(ciphers or DEFAULT_CIPHERS) + + 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): + """ + All arguments except for server_hostname and ssl_context 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. This is not + supported on Python 2.6 as the ssl module does not support it. + """ + context = ssl_context + if context is None: + context = create_urllib3_context(ssl_version, cert_reqs, + ciphers=ciphers) + + if ca_certs: + try: + context.load_verify_locations(ca_certs) + except IOError as e: # Platform-specific: Python 2.6, 2.7, 3.2 + 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 + if certfile: + context.load_cert_chain(certfile, keyfile) + if HAS_SNI: # Platform-specific: OpenSSL with enabled SNI + return context.wrap_socket(sock, server_hostname=server_hostname) + return context.wrap_socket(sock) |