# Wrapper module for _ssl, providing some additional facilities

# implemented in Python. Written by Bill Janssen.

"""This module provides some more Pythonic support for SSL.

Object types:

SSLSocket -- subtype of socket.socket which does SSL over the socket

Exceptions:

SSLError -- exception raised for I/O errors

Functions:

cert_time_to_seconds -- convert time string used for certificate

notBefore and notAfter functions to integer

seconds past the Epoch (the time values

returned from time.time())

fetch_server_certificate (HOST, PORT) -- fetch the certificate provided

by the server running on HOST at port PORT. No

validation of the certificate is performed.

Integer constants:

SSL_ERROR_ZERO_RETURN

SSL_ERROR_WANT_READ

SSL_ERROR_WANT_WRITE

SSL_ERROR_WANT_X509_LOOKUP

SSL_ERROR_SYSCALL

SSL_ERROR_SSL

SSL_ERROR_WANT_CONNECT

SSL_ERROR_EOF

SSL_ERROR_INVALID_ERROR_CODE

The following group define certificate requirements that one side is

allowing/requiring from the other side:

CERT_NONE - no certificates from the other side are required (or will

be looked at if provided)

CERT_OPTIONAL - certificates are not required, but if provided will be

validated, and if validation fails, the connection will

also fail

CERT_REQUIRED - certificates are required, and will be validated, and

if validation fails, the connection will also fail

The following constants identify various SSL protocol variants:

PROTOCOL_SSLv2

PROTOCOL_SSLv3

PROTOCOL_SSLv23

PROTOCOL_TLS

PROTOCOL_TLS_CLIENT

PROTOCOL_TLS_SERVER

PROTOCOL_TLSv1

PROTOCOL_TLSv1_1

PROTOCOL_TLSv1_2

The following constants identify various SSL alert message descriptions as per

http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-6

ALERT_DESCRIPTION_CLOSE_NOTIFY

ALERT_DESCRIPTION_UNEXPECTED_MESSAGE

ALERT_DESCRIPTION_BAD_RECORD_MAC

ALERT_DESCRIPTION_RECORD_OVERFLOW

ALERT_DESCRIPTION_DECOMPRESSION_FAILURE

ALERT_DESCRIPTION_HANDSHAKE_FAILURE

ALERT_DESCRIPTION_BAD_CERTIFICATE

ALERT_DESCRIPTION_UNSUPPORTED_CERTIFICATE

ALERT_DESCRIPTION_CERTIFICATE_REVOKED

ALERT_DESCRIPTION_CERTIFICATE_EXPIRED

ALERT_DESCRIPTION_CERTIFICATE_UNKNOWN

ALERT_DESCRIPTION_ILLEGAL_PARAMETER

ALERT_DESCRIPTION_UNKNOWN_CA

ALERT_DESCRIPTION_ACCESS_DENIED

ALERT_DESCRIPTION_DECODE_ERROR

ALERT_DESCRIPTION_DECRYPT_ERROR

ALERT_DESCRIPTION_PROTOCOL_VERSION

ALERT_DESCRIPTION_INSUFFICIENT_SECURITY

ALERT_DESCRIPTION_INTERNAL_ERROR

ALERT_DESCRIPTION_USER_CANCELLED

ALERT_DESCRIPTION_NO_RENEGOTIATION

ALERT_DESCRIPTION_UNSUPPORTED_EXTENSION

ALERT_DESCRIPTION_CERTIFICATE_UNOBTAINABLE

ALERT_DESCRIPTION_UNRECOGNIZED_NAME

ALERT_DESCRIPTION_BAD_CERTIFICATE_STATUS_RESPONSE

ALERT_DESCRIPTION_BAD_CERTIFICATE_HASH_VALUE

ALERT_DESCRIPTION_UNKNOWN_PSK_IDENTITY

"""

import sys

import os

from collections import namedtuple

from enum import Enum as _Enum, IntEnum as _IntEnum, IntFlag as _IntFlag

import _ssl # if we can't import it, let the error propagate

from _ssl import OPENSSL_VERSION_NUMBER, OPENSSL_VERSION_INFO, OPENSSL_VERSION

from _ssl import _SSLContext, MemoryBIO, SSLSession

from _ssl import (

SSLError, SSLZeroReturnError, SSLWantReadError, SSLWantWriteError,

SSLSyscallError, SSLEOFError, SSLCertVerificationError

)

from _ssl import txt2obj as _txt2obj, nid2obj as _nid2obj

from _ssl import RAND_status, RAND_add, RAND_bytes, RAND_pseudo_bytes

try:

from _ssl import RAND_egd

except ImportError:

# LibreSSL does not provide RAND_egd

pass

from _ssl import (

HAS_SNI, HAS_ECDH, HAS_NPN, HAS_ALPN, HAS_SSLv2, HAS_SSLv3, HAS_TLSv1,

HAS_TLSv1_1, HAS_TLSv1_2, HAS_TLSv1_3

)

from _ssl import _DEFAULT_CIPHERS, _OPENSSL_API_VERSION

_IntEnum._convert_(

'_SSLMethod', __name__,

lambda name: name.startswith('PROTOCOL_') and name != 'PROTOCOL_SSLv23',

source=_ssl)

_IntFlag._convert_(

'Options', __name__,

lambda name: name.startswith('OP_'),

source=_ssl)

_IntEnum._convert_(

'AlertDescription', __name__,

lambda name: name.startswith('ALERT_DESCRIPTION_'),

source=_ssl)

_IntEnum._convert_(

'SSLErrorNumber', __name__,

lambda name: name.startswith('SSL_ERROR_'),

source=_ssl)

_IntFlag._convert_(

'VerifyFlags', __name__,

lambda name: name.startswith('VERIFY_'),

source=_ssl)

_IntEnum._convert_(

'VerifyMode', __name__,

lambda name: name.startswith('CERT_'),

source=_ssl)

PROTOCOL_SSLv23 = _SSLMethod.PROTOCOL_SSLv23 = _SSLMethod.PROTOCOL_TLS

_PROTOCOL_NAMES = {value: name for name, value in _SSLMethod.__members__.items()}

_SSLv2_IF_EXISTS = getattr(_SSLMethod, 'PROTOCOL_SSLv2', None)

class TLSVersion(_IntEnum):

MINIMUM_SUPPORTED = _ssl.PROTO_MINIMUM_SUPPORTED

SSLv3 = _ssl.PROTO_SSLv3

TLSv1 = _ssl.PROTO_TLSv1

TLSv1_1 = _ssl.PROTO_TLSv1_1

TLSv1_2 = _ssl.PROTO_TLSv1_2

TLSv1_3 = _ssl.PROTO_TLSv1_3

MAXIMUM_SUPPORTED = _ssl.PROTO_MAXIMUM_SUPPORTED

class _TLSContentType(_IntEnum):

"""Content types (record layer)

See RFC 8446, section B.1

"""

CHANGE_CIPHER_SPEC = 20

ALERT = 21

HANDSHAKE = 22

APPLICATION_DATA = 23

# pseudo content types

HEADER = 0x100

INNER_CONTENT_TYPE = 0x101

class _TLSAlertType(_IntEnum):

"""Alert types for TLSContentType.ALERT messages

See RFC 8466, section B.2

"""

CLOSE_NOTIFY = 0

UNEXPECTED_MESSAGE = 10

BAD_RECORD_MAC = 20

DECRYPTION_FAILED = 21

RECORD_OVERFLOW = 22

DECOMPRESSION_FAILURE = 30

HANDSHAKE_FAILURE = 40

NO_CERTIFICATE = 41

BAD_CERTIFICATE = 42

UNSUPPORTED_CERTIFICATE = 43

CERTIFICATE_REVOKED = 44

CERTIFICATE_EXPIRED = 45

CERTIFICATE_UNKNOWN = 46

ILLEGAL_PARAMETER = 47

UNKNOWN_CA = 48

ACCESS_DENIED = 49

DECODE_ERROR = 50

DECRYPT_ERROR = 51

EXPORT_RESTRICTION = 60

PROTOCOL_VERSION = 70

INSUFFICIENT_SECURITY = 71

INTERNAL_ERROR = 80

INAPPROPRIATE_FALLBACK = 86

USER_CANCELED = 90

NO_RENEGOTIATION = 100

MISSING_EXTENSION = 109

UNSUPPORTED_EXTENSION = 110

CERTIFICATE_UNOBTAINABLE = 111

UNRECOGNIZED_NAME = 112

BAD_CERTIFICATE_STATUS_RESPONSE = 113

BAD_CERTIFICATE_HASH_VALUE = 114

UNKNOWN_PSK_IDENTITY = 115

CERTIFICATE_REQUIRED = 116

NO_APPLICATION_PROTOCOL = 120

class _TLSMessageType(_IntEnum):

"""Message types (handshake protocol)

See RFC 8446, section B.3

"""

HELLO_REQUEST = 0

CLIENT_HELLO = 1

SERVER_HELLO = 2

HELLO_VERIFY_REQUEST = 3

NEWSESSION_TICKET = 4

END_OF_EARLY_DATA = 5

HELLO_RETRY_REQUEST = 6

ENCRYPTED_EXTENSIONS = 8

CERTIFICATE = 11

SERVER_KEY_EXCHANGE = 12

CERTIFICATE_REQUEST = 13

SERVER_DONE = 14

CERTIFICATE_VERIFY = 15

CLIENT_KEY_EXCHANGE = 16

FINISHED = 20

CERTIFICATE_URL = 21

CERTIFICATE_STATUS = 22

SUPPLEMENTAL_DATA = 23

KEY_UPDATE = 24

NEXT_PROTO = 67

MESSAGE_HASH = 254

CHANGE_CIPHER_SPEC = 0x0101

if sys.platform == "win32":

from _ssl import enum_certificates, enum_crls

from socket import socket, SOCK_STREAM, create_connection

from socket import SOL_SOCKET, SO_TYPE

import socket as _socket

import base64 # for DER-to-PEM translation

import errno

import warnings

socket_error = OSError # keep that public name in module namespace

CHANNEL_BINDING_TYPES = ['tls-unique']

HAS_NEVER_CHECK_COMMON_NAME = hasattr(_ssl, 'HOSTFLAG_NEVER_CHECK_SUBJECT')

_RESTRICTED_SERVER_CIPHERS = _DEFAULT_CIPHERS

CertificateError = SSLCertVerificationError

def _dnsname_match(dn, hostname):

"""Matching according to RFC 6125, section 6.4.3

- Hostnames are compared lower case.

- For IDNA, both dn and hostname must be encoded as IDN A-label (ACE).

- Partial wildcards like 'www*.example.org', multiple wildcards, sole

wildcard or wildcards in labels other then the left-most label are not

supported and a CertificateError is raised.

- A wildcard must match at least one character.

"""

if not dn:

return False

wildcards = dn.count('*')

# speed up common case w/o wildcards

if not wildcards:

return dn.lower() == hostname.lower()

if wildcards > 1:

raise CertificateError(

"too many wildcards in certificate DNS name: {!r}.".format(dn))

dn_leftmost, sep, dn_remainder = dn.partition('.')

if '*' in dn_remainder:

# Only match wildcard in leftmost segment.

raise CertificateError(

"wildcard can only be present in the leftmost label: "

"{!r}.".format(dn))

if not sep:

# no right side

raise CertificateError(

"sole wildcard without additional labels are not support: "

"{!r}.".format(dn))

if dn_leftmost != '*':

# no partial wildcard matching

raise CertificateError(

"partial wildcards in leftmost label are not supported: "

"{!r}.".format(dn))

hostname_leftmost, sep, hostname_remainder = hostname.partition('.')

if not hostname_leftmost or not sep:

# wildcard must match at least one char

return False

return dn_remainder.lower() == hostname_remainder.lower()

def _inet_paton(ipname):

"""Try to convert an IP address to packed binary form

Supports IPv4 addresses on all platforms and IPv6 on platforms with IPv6

support.

"""

# inet_aton() also accepts strings like '1', '127.1', some also trailing

# data like '127.0.0.1 whatever'.

try:

addr = _socket.inet_aton(ipname)

except OSError:

# not an IPv4 address

pass

else:

if _socket.inet_ntoa(addr) == ipname:

# only accept injective ipnames

return addr

else:

# refuse for short IPv4 notation and additional trailing data

raise ValueError(

"{!r} is not a quad-dotted IPv4 address.".format(ipname)

)

try:

return _socket.inet_pton(_socket.AF_INET6, ipname)

except OSError:

raise ValueError("{!r} is neither an IPv4 nor an IP6 "

"address.".format(ipname))

except AttributeError:

# AF_INET6 not available

pass

raise ValueError("{!r} is not an IPv4 address.".format(ipname))

def _ipaddress_match(cert_ipaddress, host_ip):

"""Exact matching of IP addresses.

RFC 6125 explicitly doesn't define an algorithm for this

(section 1.7.2 - "Out of Scope").

"""

# OpenSSL may add a trailing newline to a subjectAltName's IP address,

# commonly woth IPv6 addresses. Strip off trailing \n.

ip = _inet_paton(cert_ipaddress.rstrip())

return ip == host_ip

def match_hostname(cert, hostname):

"""Verify that *cert* (in decoded format as returned by

SSLSocket.getpeercert()) matches the *hostname*. RFC 2818 and RFC 6125

rules are followed.

The function matches IP addresses rather than dNSNames if hostname is a

valid ipaddress string. IPv4 addresses are supported on all platforms.

IPv6 addresses are supported on platforms with IPv6 support (AF_INET6

and inet_pton).

CertificateError is raised on failure. On success, the function

returns nothing.

"""

if not cert:

raise ValueError("empty or no certificate, match_hostname needs a "

"SSL socket or SSL context with either "

"CERT_OPTIONAL or CERT_REQUIRED")

try:

host_ip = _inet_paton(hostname)

except ValueError:

# Not an IP address (common case)

host_ip = None

dnsnames = []

san = cert.get('subjectAltName', ())

for key, value in san:

if key == 'DNS':

if host_ip is None and _dnsname_match(value, hostname):

return

dnsnames.append(value)

elif key == 'IP Address':

if host_ip is not None and _ipaddress_match(value, host_ip):

return

dnsnames.append(value)

if not dnsnames:

# The subject is only checked when there is no dNSName entry

# in subjectAltName

for sub in cert.get('subject', ()):

for key, value in sub:

# XXX according to RFC 2818, the most specific Common Name

# must be used.

if key == 'commonName':

if _dnsname_match(value, hostname):

return

dnsnames.append(value)

if len(dnsnames) > 1:

raise CertificateError("hostname %r "

"doesn't match either of %s"

% (hostname, ', '.join(map(repr, dnsnames))))

elif len(dnsnames) == 1:

raise CertificateError("hostname %r "

"doesn't match %r"

% (hostname, dnsnames[0]))

else:

raise CertificateError("no appropriate commonName or "

"subjectAltName fields were found")

DefaultVerifyPaths = namedtuple("DefaultVerifyPaths",

"cafile capath openssl_cafile_env openssl_cafile openssl_capath_env "

"openssl_capath")

def get_default_verify_paths():

"""Return paths to default cafile and capath.

"""

parts = _ssl.get_default_verify_paths()

# environment vars shadow paths

cafile = os.environ.get(parts[0], parts[1])

capath = os.environ.get(parts[2], parts[3])

return DefaultVerifyPaths(cafile if os.path.isfile(cafile) else None,

capath if os.path.isdir(capath) else None,

*parts)

class _ASN1Object(namedtuple("_ASN1Object", "nid shortname longname oid")):

"""ASN.1 object identifier lookup

"""

__slots__ = ()

def __new__(cls, oid):

return super().__new__(cls, *_txt2obj(oid, name=False))

@classmethod

def fromnid(cls, nid):

"""Create _ASN1Object from OpenSSL numeric ID

"""

return super().__new__(cls, *_nid2obj(nid))

@classmethod

def fromname(cls, name):

"""Create _ASN1Object from short name, long name or OID

"""

return super().__new__(cls, *_txt2obj(name, name=True))

class Purpose(_ASN1Object, _Enum):

"""SSLContext purpose flags with X509v3 Extended Key Usage objects

"""

SERVER_AUTH = '1.3.6.1.5.5.7.3.1'

CLIENT_AUTH = '1.3.6.1.5.5.7.3.2'

class SSLContext(_SSLContext):

"""An SSLContext holds various SSL-related configuration options and

data, such as certificates and possibly a private key."""

_windows_cert_stores = ("CA", "ROOT")

sslsocket_class = None # SSLSocket is assigned later.

sslobject_class = None # SSLObject is assigned later.

def __new__(cls, protocol=PROTOCOL_TLS, *args, **kwargs):

self = _SSLContext.__new__(cls, protocol)

return self

def _encode_hostname(self, hostname):

if hostname is None:

return None

elif isinstance(hostname, str):

return hostname.encode('idna').decode('ascii')

else:

return hostname.decode('ascii')

def wrap_socket(self, sock, server_side=False,

do_handshake_on_connect=True,

suppress_ragged_eofs=True,

server_hostname=None, session=None):

# SSLSocket class handles server_hostname encoding before it calls

# ctx._wrap_socket()

return self.sslsocket_class._create(

sock=sock,

server_side=server_side,

do_handshake_on_connect=do_handshake_on_connect,

suppress_ragged_eofs=suppress_ragged_eofs,

server_hostname=server_hostname,

context=self,

session=session

)

def wrap_bio(self, incoming, outgoing, server_side=False,

server_hostname=None, session=None):

# Need to encode server_hostname here because _wrap_bio() can only

# handle ASCII str.

return self.sslobject_class._create(

incoming, outgoing, server_side=server_side,

server_hostname=self._encode_hostname(server_hostname),

session=session, context=self,

)

def set_npn_protocols(self, npn_protocols):

protos = bytearray()

for protocol in npn_protocols:

b = bytes(protocol, 'ascii')

if len(b) == 0 or len(b) > 255:

raise SSLError('NPN protocols must be 1 to 255 in length')

protos.append(len(b))

protos.extend(b)

self._set_npn_protocols(protos)

def set_servername_callback(self, server_name_callback):

if server_name_callback is None:

self.sni_callback = None

else:

if not callable(server_name_callback):

raise TypeError("not a callable object")

def shim_cb(sslobj, servername, sslctx):

servername = self._encode_hostname(servername)

return server_name_callback(sslobj, servername, sslctx)

self.sni_callback = shim_cb

def set_alpn_protocols(self, alpn_protocols):

protos = bytearray()

for protocol in alpn_protocols:

b = bytes(protocol, 'ascii')

if len(b) == 0 or len(b) > 255:

raise SSLError('ALPN protocols must be 1 to 255 in length')

protos.append(len(b))

protos.extend(b)

self._set_alpn_protocols(protos)

def _load_windows_store_certs(self, storename, purpose):

certs = bytearray()

try:

for cert, encoding, trust in enum_certificates(storename):

# CA certs are never PKCS#7 encoded

if encoding == "x509_asn":

if trust is True or purpose.oid in trust:

certs.extend(cert)

except PermissionError:

warnings.warn("unable to enumerate Windows certificate store")

if certs:

self.load_verify_locations(cadata=certs)

return certs

def load_default_certs(self, purpose=Purpose.SERVER_AUTH):

if not isinstance(purpose, _ASN1Object):

raise TypeError(purpose)

if sys.platform == "win32":

for storename in self._windows_cert_stores:

self._load_windows_store_certs(storename, purpose)

self.set_default_verify_paths()

if hasattr(_SSLContext, 'minimum_version'):

@property

def minimum_version(self):

return TLSVersion(super().minimum_version)

@minimum_version.setter

def minimum_version(self, value):

if value == TLSVersion.SSLv3:

self.options &= ~Options.OP_NO_SSLv3

super(SSLContext, SSLContext).minimum_version.__set__(self, value)

@property

def maximum_version(self):

return TLSVersion(super().maximum_version)

@maximum_version.setter

def maximum_version(self, value):

super(SSLContext, SSLContext).maximum_version.__set__(self, value)

@property

def options(self):

return Options(super().options)

@options.setter

def options(self, value):

super(SSLContext, SSLContext).options.__set__(self, value)

if hasattr(_ssl, 'HOSTFLAG_NEVER_CHECK_SUBJECT'):

@property

def hostname_checks_common_name(self):

ncs = self._host_flags & _ssl.HOSTFLAG_NEVER_CHECK_SUBJECT

return ncs != _ssl.HOSTFLAG_NEVER_CHECK_SUBJECT

@hostname_checks_common_name.setter

def hostname_checks_common_name(self, value):

if value:

self._host_flags &= ~_ssl.HOSTFLAG_NEVER_CHECK_SUBJECT

else:

self._host_flags |= _ssl.HOSTFLAG_NEVER_CHECK_SUBJECT

else:

@property

def hostname_checks_common_name(self):

return True

@property

def _msg_callback(self):

"""TLS message callback

The message callback provides a debugging hook to analyze TLS

connections. The callback is called for any TLS protocol message

(header, handshake, alert, and more), but not for application data.

Due to technical limitations, the callback can't be used to filter

traffic or to abort a connection. Any exception raised in the

callback is delayed until the handshake, read, or write operation

has been performed.

def msg_cb(conn, direction, version, content_type, msg_type, data):

pass

conn

:class:`SSLSocket` or :class:`SSLObject` instance

direction

``read`` or ``write``

version

:class:`TLSVersion` enum member or int for unknown version. For a

frame header, it's the header version.

content_type

:class:`_TLSContentType` enum member or int for unsupported

content type.

msg_type

Either a :class:`_TLSContentType` enum number for a header

message, a :class:`_TLSAlertType` enum member for an alert

message, a :class:`_TLSMessageType` enum member for other

messages, or int for unsupported message types.

data

Raw, decrypted message content as bytes

"""

inner = super()._msg_callback

if inner is not None:

return inner.user_function

else:

return None

@_msg_callback.setter

def _msg_callback(self, callback):

if callback is None:

super(SSLContext, SSLContext)._msg_callback.__set__(self, None)

return

if not hasattr(callback, '__call__'):

raise TypeError(f"{callback} is not callable.")

def inner(conn, direction, version, content_type, msg_type, data):

try:

version = TLSVersion(version)

except ValueError:

pass

try:

content_type = _TLSContentType(content_type)

except ValueError:

pass

if content_type == _TLSContentType.HEADER:

msg_enum = _TLSContentType

elif content_type == _TLSContentType.ALERT:

msg_enum = _TLSAlertType

else:

msg_enum = _TLSMessageType

try:

msg_type = msg_enum(msg_type)

except ValueError:

pass

return callback(conn, direction, version,

content_type, msg_type, data)

inner.user_function = callback

super(SSLContext, SSLContext)._msg_callback.__set__(self, inner)

@property

def protocol(self):

return _SSLMethod(super().protocol)

@property

def verify_flags(self):

return VerifyFlags(super().verify_flags)

@verify_flags.setter

def verify_flags(self, value):

super(SSLContext, SSLContext).verify_flags.__set__(self, value)

@property

def verify_mode(self):

value = super().verify_mode

try:

return VerifyMode(value)

except ValueError:

return value

@verify_mode.setter

def verify_mode(self, value):

super(SSLContext, SSLContext).verify_mode.__set__(self, value)

def create_default_context(purpose=Purpose.SERVER_AUTH, *, cafile=None,

capath=None, cadata=None):

"""Create a SSLContext object with default settings.

NOTE: The protocol and settings may change anytime without prior

deprecation. The values represent a fair balance between maximum

compatibility and security.

"""

if not isinstance(purpose, _ASN1Object):

raise TypeError(purpose)

# SSLContext sets OP_NO_SSLv2, OP_NO_SSLv3, OP_NO_COMPRESSION,

# OP_CIPHER_SERVER_PREFERENCE, OP_SINGLE_DH_USE and OP_SINGLE_ECDH_USE

# by default.

context = SSLContext(PROTOCOL_TLS)

if purpose == Purpose.SERVER_AUTH:

# verify certs and host name in client mode

context.verify_mode = CERT_REQUIRED

context.check_hostname = True

if cafile or capath or cadata:

context.load_verify_locations(cafile, capath, cadata)

elif context.verify_mode != CERT_NONE:

# no explicit cafile, capath or cadata but the verify mode is

# CERT_OPTIONAL or CERT_REQUIRED. Let's try to load default system

# root CA certificates for the given purpose. This may fail silently.

context.load_default_certs(purpose)

# OpenSSL 1.1.1 keylog file

if hasattr(context, 'keylog_filename'):

keylogfile = os.environ.get('SSLKEYLOGFILE')

if keylogfile and not sys.flags.ignore_environment:

context.keylog_filename = keylogfile

return context

def _create_unverified_context(protocol=PROTOCOL_TLS, *, cert_reqs=CERT_NONE,

check_hostname=False, purpose=Purpose.SERVER_AUTH,

certfile=None, keyfile=None,

cafile=None, capath=None, cadata=None):

"""Create a SSLContext object for Python stdlib modules

All Python stdlib modules shall use this function to create SSLContext

objects in order to keep common settings in one place. The configuration

is less restrict than create_default_context()'s to increase backward

compatibility.

"""

if not isinstance(purpose, _ASN1Object):

raise TypeError(purpose)

# SSLContext sets OP_NO_SSLv2, OP_NO_SSLv3, OP_NO_COMPRESSION,

# OP_CIPHER_SERVER_PREFERENCE, OP_SINGLE_DH_USE and OP_SINGLE_ECDH_USE

# by default.

context = SSLContext(protocol)

if not check_hostname:

context.check_hostname = False

if cert_reqs is not None:

context.verify_mode = cert_reqs

if check_hostname:

context.check_hostname = True

if keyfile and not certfile:

raise ValueError("certfile must be specified")

if certfile or keyfile:

context.load_cert_chain(certfile, keyfile)

# load CA root certs

if cafile or capath or cadata:

context.load_verify_locations(cafile, capath, cadata)

elif context.verify_mode != CERT_NONE:

# no explicit cafile, capath or cadata but the verify mode is

# CERT_OPTIONAL or CERT_REQUIRED. Let's try to load default system

# root CA certificates for the given purpose. This may fail silently.

context.load_default_certs(purpose)

# OpenSSL 1.1.1 keylog file

if hasattr(context, 'keylog_filename'):

keylogfile = os.environ.get('SSLKEYLOGFILE')

if keylogfile and not sys.flags.ignore_environment:

context.keylog_filename = keylogfile

return context

# Used by http.client if no context is explicitly passed.

_create_default_https_context = create_default_context

# Backwards compatibility alias, even though it's not a public name.

_create_stdlib_context = _create_unverified_context

class SSLObject:

"""This class implements an interface on top of a low-level SSL object as

implemented by OpenSSL. This object captures the state of an SSL connection

but does not provide any network IO itself. IO needs to be performed

through separate "BIO" objects which are OpenSSL's IO abstraction layer.

This class does not have a public constructor. Instances are returned by

``SSLContext.wrap_bio``. This class is typically used by framework authors

that want to implement asynchronous IO for SSL through memory buffers.

When compared to ``SSLSocket``, this object lacks the following features:

* Any form of network IO, including methods such as ``recv`` and ``send``.

* The ``do_handshake_on_connect`` and ``suppress_ragged_eofs`` machinery.

"""

def __init__(self, *args, **kwargs):

raise TypeError(

f"{self.__class__.__name__} does not have a public "

f"constructor. Instances are returned by SSLContext.wrap_bio()."

)

@classmethod

def _create(cls, incoming, outgoing, server_side=False,

server_hostname=None, session=None, context=None):

self = cls.__new__(cls)

sslobj = context._wrap_bio(

incoming, outgoing, server_side=server_side,

server_hostname=server_hostname,

owner=self, session=session

)

self._sslobj = sslobj

return self

@property

def context(self):

"""The SSLContext that is currently in use."""

return self._sslobj.context

@context.setter

def context(self, ctx):

self._sslobj.context = ctx

@property

def session(self):

"""The SSLSession for client socket."""

return self._sslobj.session

@session.setter

def session(self, session):

self._sslobj.session = session

@property

def session_reused(self):

"""Was the client session reused during handshake"""

return self._sslobj.session_reused

@property

def server_side(self):

"""Whether this is a server-side socket."""

return self._sslobj.server_side

@property

def server_hostname(self):

"""The currently set server hostname (for SNI), or ``None`` if no

server hostname is set."""

return self._sslobj.server_hostname

def read(self, len=1024, buffer=None):

"""Read up to 'len' bytes from the SSL object and return them.

If 'buffer' is provided, read into this buffer and return the number of

bytes read.

"""

if buffer is not None:

v = self._sslobj.read(len, buffer)

else:

v = self._sslobj.read(len)

return v

def write(self, data):

"""Write 'data' to the SSL object and return the number of bytes

written.

The 'data' argument must support the buffer interface.

"""

return self._sslobj.write(data)

def getpeercert(self, binary_form=False):

"""Returns a formatted version of the data in the certificate provided

by the other end of the SSL channel.

Return None if no certificate was provided, {} if a certificate was

provided, but not validated.

"""

return self._sslobj.getpeercert(binary_form)

def selected_npn_protocol(self):

"""Return the currently selected NPN protocol as a string, or ``None``

if a next protocol was not negotiated or if NPN is not supported by one

of the peers."""

def selected_alpn_protocol(self):

"""Return the currently selected ALPN protocol as a string, or ``None``

if a next protocol was not negotiated or if ALPN is not supported by one

of the peers."""

return self._sslobj.selected_alpn_protocol()

def cipher(self):

"""Return the currently selected cipher as a 3-tuple ``(name,

ssl_version, secret_bits)``."""

return self._sslobj.cipher()

def shared_ciphers(self):

"""Return a list of ciphers shared by the client during the handshake or

None if this is not a valid server connection.

"""

return self._sslobj.shared_ciphers()

def compression(self):

"""Return the current compression algorithm in use, or ``None`` if

compression was not negotiated or not supported by one of the peers."""

return self._sslobj.compression()

def pending(self):

"""Return the number of bytes that can be read immediately."""

return self._sslobj.pending()

def do_handshake(self):

"""Start the SSL/TLS handshake."""

self._sslobj.do_handshake()

def unwrap(self):

"""Start the SSL shutdown handshake."""

return self._sslobj.shutdown()

def get_channel_binding(self, cb_type="tls-unique"):

"""Get channel binding data for current connection. Raise ValueError

if the requested `cb_type` is not supported. Return bytes of the data

or None if the data is not available (e.g. before the handshake)."""

return self._sslobj.get_channel_binding(cb_type)

def version(self):

"""Return a string identifying the protocol version used by the

current SSL channel. """

return self._sslobj.version()

def verify_client_post_handshake(self):

return self._sslobj.verify_client_post_handshake()

def _sslcopydoc(func):

"""Copy docstring from SSLObject to SSLSocket"""

func.__doc__ = getattr(SSLObject, func.__name__).__doc__

return func

class SSLSocket(socket):

"""This class implements a subtype of socket.socket that wraps

the underlying OS socket in an SSL context when necessary, and

provides read and write methods over that channel. """

def __init__(self, *args, **kwargs):

raise TypeError(

f"{self.__class__.__name__} does not have a public "

f"constructor. Instances are returned by "

f"SSLContext.wrap_socket()."

)

@classmethod

def _create(cls, sock, server_side=False, do_handshake_on_connect=True,

suppress_ragged_eofs=True, server_hostname=None,

context=None, session=None):

if sock.getsockopt(SOL_SOCKET, SO_TYPE) != SOCK_STREAM:

raise NotImplementedError("only stream sockets are supported")

if server_side:

if server_hostname:

raise ValueError("server_hostname can only be specified "

"in client mode")

if session is not None:

raise ValueError("session can only be specified in "

"client mode")

if context.check_hostname and not server_hostname:

raise ValueError("check_hostname requires server_hostname")

kwargs = dict(

family=sock.family, type=sock.type, proto=sock.proto,

fileno=sock.fileno()

)

self = cls.__new__(cls, **kwargs)