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from binascii import hexlify, unhexlify
from hashlib import md5, sha1
from ..exceptions import SSLError
try: # Test for SSL features
SSLContext = None
HAS_SNI = False
import ssl
from ssl import wrap_socket, CERT_NONE, PROTOCOL_SSLv23
from ssl import SSLContext # Modern SSL?
from ssl import HAS_SNI # Has SNI?
except ImportError:
pass
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
}
fingerprint = fingerprint.replace(':', '').lower()
digest_length, rest = divmod(len(fingerprint), 2)
if rest 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
if SSLContext is not None: # Python 3.2+
def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
ca_certs=None, server_hostname=None,
ssl_version=None):
"""
All arguments except `server_hostname` have the same meaning as for
:func:`ssl.wrap_socket`
:param server_hostname:
Hostname of the expected certificate
"""
context = SSLContext(ssl_version)
context.verify_mode = cert_reqs
# Disable TLS compression to migitate CRIME attack (issue #309)
OP_NO_COMPRESSION = 0x20000
context.options |= OP_NO_COMPRESSION
if ca_certs:
try:
context.load_verify_locations(ca_certs)
# Py32 raises IOError
# Py33 raises FileNotFoundError
except Exception as e: # Reraise as SSLError
raise SSLError(e)
if certfile:
# FIXME: This block needs a test.
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)
else: # Python 3.1 and earlier
def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
ca_certs=None, server_hostname=None,
ssl_version=None):
return wrap_socket(sock, keyfile=keyfile, certfile=certfile,
ca_certs=ca_certs, cert_reqs=cert_reqs,
ssl_version=ssl_version)
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