JezK
Edit File: pyopenssl.py
""" TLS with SNI_-support for Python 2. Follow these instructions if you would like to verify TLS certificates in Python 2. Note, the default libraries do *not* do certificate checking; you need to do additional work to validate certificates yourself. This needs the following packages installed: * `pyOpenSSL`_ (tested with 16.0.0) * `cryptography`_ (minimum 1.3.4, from pyopenssl) * `idna`_ (minimum 2.0, from cryptography) However, pyopenssl depends on cryptography, which depends on idna, so while we use all three directly here we end up having relatively few packages required. You can install them with the following command: .. code-block:: bash $ python -m pip install pyopenssl cryptography idna To activate certificate checking, call :func:`~urllib3.contrib.pyopenssl.inject_into_urllib3` from your Python code before you begin making HTTP requests. This can be done in a ``sitecustomize`` module, or at any other time before your application begins using ``urllib3``, like this: .. code-block:: python try: import pip._vendor.urllib3.contrib.pyopenssl as pyopenssl pyopenssl.inject_into_urllib3() except ImportError: pass Now you can use :mod:`urllib3` as you normally would, and it will support SNI when the required modules are installed. Activating this module also has the positive side effect of disabling SSL/TLS compression in Python 2 (see `CRIME attack`_). .. _sni: https://en.wikipedia.org/wiki/Server_Name_Indication .. _crime attack: https://en.wikipedia.org/wiki/CRIME_(security_exploit) .. _pyopenssl: https://www.pyopenssl.org .. _cryptography: https://cryptography.io .. _idna: https://github.com/kjd/idna """ from __future__ import absolute_import import OpenSSL.crypto import OpenSSL.SSL from cryptography import x509 from cryptography.hazmat.backends.openssl import backend as openssl_backend try: from cryptography.x509 import UnsupportedExtension except ImportError: # UnsupportedExtension is gone in cryptography >= 2.1.0 class UnsupportedExtension(Exception): pass from io import BytesIO from socket import error as SocketError from socket import timeout try: # Platform-specific: Python 2 from socket import _fileobject except ImportError: # Platform-specific: Python 3 _fileobject = None from ..packages.backports.makefile import backport_makefile import logging import ssl import sys import warnings from .. import util from ..packages import six from ..util.ssl_ import PROTOCOL_TLS_CLIENT warnings.warn( "'urllib3.contrib.pyopenssl' module is deprecated and will be removed " "in a future release of urllib3 2.x. Read more in this issue: " "https://github.com/urllib3/urllib3/issues/2680", category=DeprecationWarning, stacklevel=2, ) __all__ = ["inject_into_urllib3", "extract_from_urllib3"] # SNI always works. HAS_SNI = True # Map from urllib3 to PyOpenSSL compatible parameter-values. _openssl_versions = { util.PROTOCOL_TLS: OpenSSL.SSL.SSLv23_METHOD, PROTOCOL_TLS_CLIENT: OpenSSL.SSL.SSLv23_METHOD, ssl.PROTOCOL_TLSv1: OpenSSL.SSL.TLSv1_METHOD, } if hasattr(ssl, "PROTOCOL_SSLv3") and hasattr(OpenSSL.SSL, "SSLv3_METHOD"): _openssl_versions[ssl.PROTOCOL_SSLv3] = OpenSSL.SSL.SSLv3_METHOD if hasattr(ssl, "PROTOCOL_TLSv1_1") and hasattr(OpenSSL.SSL, "TLSv1_1_METHOD"): _openssl_versions[ssl.PROTOCOL_TLSv1_1] = OpenSSL.SSL.TLSv1_1_METHOD if hasattr(ssl, "PROTOCOL_TLSv1_2") and hasattr(OpenSSL.SSL, "TLSv1_2_METHOD"): _openssl_versions[ssl.PROTOCOL_TLSv1_2] = OpenSSL.SSL.TLSv1_2_METHOD _stdlib_to_openssl_verify = { ssl.CERT_NONE: OpenSSL.SSL.VERIFY_NONE, ssl.CERT_OPTIONAL: OpenSSL.SSL.VERIFY_PEER, ssl.CERT_REQUIRED: OpenSSL.SSL.VERIFY_PEER + OpenSSL.SSL.VERIFY_FAIL_IF_NO_PEER_CERT, } _openssl_to_stdlib_verify = dict((v, k) for k, v in _stdlib_to_openssl_verify.items()) # OpenSSL will only write 16K at a time SSL_WRITE_BLOCKSIZE = 16384 orig_util_HAS_SNI = util.HAS_SNI orig_util_SSLContext = util.ssl_.SSLContext log = logging.getLogger(__name__) def inject_into_urllib3(): "Monkey-patch urllib3 with PyOpenSSL-backed SSL-support." _validate_dependencies_met() util.SSLContext = PyOpenSSLContext util.ssl_.SSLContext = PyOpenSSLContext util.HAS_SNI = HAS_SNI util.ssl_.HAS_SNI = HAS_SNI util.IS_PYOPENSSL = True util.ssl_.IS_PYOPENSSL = True def extract_from_urllib3(): "Undo monkey-patching by :func:`inject_into_urllib3`." util.SSLContext = orig_util_SSLContext util.ssl_.SSLContext = orig_util_SSLContext util.HAS_SNI = orig_util_HAS_SNI util.ssl_.HAS_SNI = orig_util_HAS_SNI util.IS_PYOPENSSL = False util.ssl_.IS_PYOPENSSL = False def _validate_dependencies_met(): """ Verifies that PyOpenSSL's package-level dependencies have been met. Throws `ImportError` if they are not met. """ # Method added in `cryptography==1.1`; not available in older versions from cryptography.x509.extensions import Extensions if getattr(Extensions, "get_extension_for_class", None) is None: raise ImportError( "'cryptography' module missing required functionality. " "Try upgrading to v1.3.4 or newer." ) # pyOpenSSL 0.14 and above use cryptography for OpenSSL bindings. The _x509 # attribute is only present on those versions. from OpenSSL.crypto import X509 x509 = X509() if getattr(x509, "_x509", None) is None: raise ImportError( "'pyOpenSSL' module missing required functionality. " "Try upgrading to v0.14 or newer." ) def _dnsname_to_stdlib(name): """ Converts a dNSName SubjectAlternativeName field to the form used by the standard library on the given Python version. Cryptography produces a dNSName as a unicode string that was idna-decoded from ASCII bytes. We need to idna-encode that string to get it back, and then on Python 3 we also need to convert to unicode via UTF-8 (the stdlib uses PyUnicode_FromStringAndSize on it, which decodes via UTF-8). If the name cannot be idna-encoded then we return None signalling that the name given should be skipped. """ def idna_encode(name): """ Borrowed wholesale from the Python Cryptography Project. It turns out that we can't just safely call `idna.encode`: it can explode for wildcard names. This avoids that problem. """ from pip._vendor import idna try: for prefix in [u"*.", u"."]: if name.startswith(prefix): name = name[len(prefix) :] return prefix.encode("ascii") + idna.encode(name) return idna.encode(name) except idna.core.IDNAError: return None # Don't send IPv6 addresses through the IDNA encoder. if ":" in name: return name name = idna_encode(name) if name is None: return None elif sys.version_info >= (3, 0): name = name.decode("utf-8") return name def get_subj_alt_name(peer_cert): """ Given an PyOpenSSL certificate, provides all the subject alternative names. """ # Pass the cert to cryptography, which has much better APIs for this. if hasattr(peer_cert, "to_cryptography"): cert = peer_cert.to_cryptography() else: der = OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_ASN1, peer_cert) cert = x509.load_der_x509_certificate(der, openssl_backend) # We want to find the SAN extension. Ask Cryptography to locate it (it's # faster than looping in Python) try: ext = cert.extensions.get_extension_for_class(x509.SubjectAlternativeName).value except x509.ExtensionNotFound: # No such extension, return the empty list. return [] except ( x509.DuplicateExtension, UnsupportedExtension, x509.UnsupportedGeneralNameType, UnicodeError, ) as e: # A problem has been found with the quality of the certificate. Assume # no SAN field is present. log.warning( "A problem was encountered with the certificate that prevented " "urllib3 from finding the SubjectAlternativeName field. This can " "affect certificate validation. The error was %s", e, ) return [] # We want to return dNSName and iPAddress fields. We need to cast the IPs # back to strings because the match_hostname function wants them as # strings. # Sadly the DNS names need to be idna encoded and then, on Python 3, UTF-8 # decoded. This is pretty frustrating, but that's what the standard library # does with certificates, and so we need to attempt to do the same. # We also want to skip over names which cannot be idna encoded. names = [ ("DNS", name) for name in map(_dnsname_to_stdlib, ext.get_values_for_type(x509.DNSName)) if name is not None ] names.extend( ("IP Address", str(name)) for name in ext.get_values_for_type(x509.IPAddress) ) return names class WrappedSocket(object): """API-compatibility wrapper for Python OpenSSL's Connection-class. Note: _makefile_refs, _drop() and _reuse() are needed for the garbage collector of pypy. """ def __init__(self, connection, socket, suppress_ragged_eofs=True): self.connection = connection self.socket = socket self.suppress_ragged_eofs = suppress_ragged_eofs self._makefile_refs = 0 self._closed = False def fileno(self): return self.socket.fileno() # Copy-pasted from Python 3.5 source code def _decref_socketios(self): if self._makefile_refs > 0: self._makefile_refs -= 1 if self._closed: self.close() def recv(self, *args, **kwargs): try: data = self.connection.recv(*args, **kwargs) except OpenSSL.SSL.SysCallError as e: if self.suppress_ragged_eofs and e.args == (-1, "Unexpected EOF"): return b"" else: raise SocketError(str(e)) except OpenSSL.SSL.ZeroReturnError: if self.connection.get_shutdown() == OpenSSL.SSL.RECEIVED_SHUTDOWN: return b"" else: raise except OpenSSL.SSL.WantReadError: if not util.wait_for_read(self.socket, self.socket.gettimeout()): raise timeout("The read operation timed out") else: return self.recv(*args, **kwargs) # TLS 1.3 post-handshake authentication except OpenSSL.SSL.Error as e: raise ssl.SSLError("read error: %r" % e) else: return data def recv_into(self, *args, **kwargs): try: return self.connection.recv_into(*args, **kwargs) except OpenSSL.SSL.SysCallError as e: if self.suppress_ragged_eofs and e.args == (-1, "Unexpected EOF"): return 0 else: raise SocketError(str(e)) except OpenSSL.SSL.ZeroReturnError: if self.connection.get_shutdown() == OpenSSL.SSL.RECEIVED_SHUTDOWN: return 0 else: raise except OpenSSL.SSL.WantReadError: if not util.wait_for_read(self.socket, self.socket.gettimeout()): raise timeout("The read operation timed out") else: return self.recv_into(*args, **kwargs) # TLS 1.3 post-handshake authentication except OpenSSL.SSL.Error as e: raise ssl.SSLError("read error: %r" % e) def settimeout(self, timeout): return self.socket.settimeout(timeout) def _send_until_done(self, data): while True: try: return self.connection.send(data) except OpenSSL.SSL.WantWriteError: if not util.wait_for_write(self.socket, self.socket.gettimeout()): raise timeout() continue except OpenSSL.SSL.SysCallError as e: raise SocketError(str(e)) def sendall(self, data): total_sent = 0 while total_sent < len(data): sent = self._send_until_done( data[total_sent : total_sent + SSL_WRITE_BLOCKSIZE] ) total_sent += sent def shutdown(self): # FIXME rethrow compatible exceptions should we ever use this self.connection.shutdown() def close(self): if self._makefile_refs < 1: try: self._closed = True return self.connection.close() except OpenSSL.SSL.Error: return else: self._makefile_refs -= 1 def getpeercert(self, binary_form=False): x509 = self.connection.get_peer_certificate() if not x509: return x509 if binary_form: return OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_ASN1, x509) return { "subject": ((("commonName", x509.get_subject().CN),),), "subjectAltName": get_subj_alt_name(x509), } def version(self): return self.connection.get_protocol_version_name() def _reuse(self): self._makefile_refs += 1 def _drop(self): if self._makefile_refs < 1: self.close() else: self._makefile_refs -= 1 if _fileobject: # Platform-specific: Python 2 def makefile(self, mode, bufsize=-1): self._makefile_refs += 1 return _fileobject(self, mode, bufsize, close=True) else: # Platform-specific: Python 3 makefile = backport_makefile WrappedSocket.makefile = makefile class PyOpenSSLContext(object): """ I am a wrapper class for the PyOpenSSL ``Context`` object. I am responsible for translating the interface of the standard library ``SSLContext`` object to calls into PyOpenSSL. """ def __init__(self, protocol): self.protocol = _openssl_versions[protocol] self._ctx = OpenSSL.SSL.Context(self.protocol) self._options = 0 self.check_hostname = False @property def options(self): return self._options @options.setter def options(self, value): self._options = value self._ctx.set_options(value) @property def verify_mode(self): return _openssl_to_stdlib_verify[self._ctx.get_verify_mode()] @verify_mode.setter def verify_mode(self, value): self._ctx.set_verify(_stdlib_to_openssl_verify[value], _verify_callback) def set_default_verify_paths(self): self._ctx.set_default_verify_paths() def set_ciphers(self, ciphers): if isinstance(ciphers, six.text_type): ciphers = ciphers.encode("utf-8") self._ctx.set_cipher_list(ciphers) def load_verify_locations(self, cafile=None, capath=None, cadata=None): if cafile is not None: cafile = cafile.encode("utf-8") if capath is not None: capath = capath.encode("utf-8") try: self._ctx.load_verify_locations(cafile, capath) if cadata is not None: self._ctx.load_verify_locations(BytesIO(cadata)) except OpenSSL.SSL.Error as e: raise ssl.SSLError("unable to load trusted certificates: %r" % e) def load_cert_chain(self, certfile, keyfile=None, password=None): self._ctx.use_certificate_chain_file(certfile) if password is not None: if not isinstance(password, six.binary_type): password = password.encode("utf-8") self._ctx.set_passwd_cb(lambda *_: password) self._ctx.use_privatekey_file(keyfile or certfile) def set_alpn_protocols(self, protocols): protocols = [six.ensure_binary(p) for p in protocols] return self._ctx.set_alpn_protos(protocols) def wrap_socket( self, sock, server_side=False, do_handshake_on_connect=True, suppress_ragged_eofs=True, server_hostname=None, ): cnx = OpenSSL.SSL.Connection(self._ctx, sock) if isinstance(server_hostname, six.text_type): # Platform-specific: Python 3 server_hostname = server_hostname.encode("utf-8") if server_hostname is not None: cnx.set_tlsext_host_name(server_hostname) cnx.set_connect_state() while True: try: cnx.do_handshake() except OpenSSL.SSL.WantReadError: if not util.wait_for_read(sock, sock.gettimeout()): raise timeout("select timed out") continue except OpenSSL.SSL.Error as e: raise ssl.SSLError("bad handshake: %r" % e) break return WrappedSocket(cnx, sock) def _verify_callback(cnx, x509, err_no, err_depth, return_code): return err_no == 0