CasperSecurity
"""
`pyOpenSSL <https://github.com/pyca/pyopenssl>`_-specific code.
"""
from __future__ import absolute_import, division, print_function
import warnings
import six
from pyasn1.codec.der.decoder import decode
from pyasn1.type.char import IA5String
from pyasn1.type.univ import ObjectIdentifier
from pyasn1_modules.rfc2459 import GeneralNames
from ._common import (
DNS_ID,
CertificateError,
DNSPattern,
IPAddress_ID,
IPAddressPattern,
SRVPattern,
URIPattern,
verify_service_identity,
)
from .exceptions import SubjectAltNameWarning
__all__ = ["verify_hostname"]
def verify_hostname(connection, hostname):
"""
Verify whether the certificate of *connection* is valid for *hostname*.
:param OpenSSL.SSL.Connection connection: A pyOpenSSL connection object.
:param unicode hostname: The hostname that *connection* should be connected
to.
:raises service_identity.VerificationError: If *connection* does not
provide a certificate that is valid for *hostname*.
:raises service_identity.CertificateError: If the certificate chain of
*connection* contains a certificate that contains invalid/unexpected
data.
:returns: ``None``
"""
verify_service_identity(
cert_patterns=extract_ids(connection.get_peer_certificate()),
obligatory_ids=[DNS_ID(hostname)],
optional_ids=[],
)
def verify_ip_address(connection, ip_address):
"""
Verify whether the certificate of *connection* is valid for *ip_address*.
:param OpenSSL.SSL.Connection connection: A pyOpenSSL connection object.
:param unicode ip_address: The IP address that *connection* should be
connected to. Can be an IPv4 or IPv6 address.
:raises service_identity.VerificationError: If *connection* does not
provide a certificate that is valid for *ip_address*.
:raises service_identity.CertificateError: If the certificate chain of
*connection* contains a certificate that contains invalid/unexpected
data.
:returns: ``None``
.. versionadded:: 18.1.0
"""
verify_service_identity(
cert_patterns=extract_ids(connection.get_peer_certificate()),
obligatory_ids=[IPAddress_ID(ip_address)],
optional_ids=[],
)
ID_ON_DNS_SRV = ObjectIdentifier("1.3.6.1.5.5.7.8.7") # id_on_dnsSRV
def extract_ids(cert):
"""
Extract all valid IDs from a certificate for service verification.
If *cert* doesn't contain any identifiers, the ``CN``s are used as DNS-IDs
as fallback.
:param OpenSSL.SSL.X509 cert: The certificate to be dissected.
:return: List of IDs.
"""
ids = []
for i in six.moves.range(cert.get_extension_count()):
ext = cert.get_extension(i)
if ext.get_short_name() == b"subjectAltName":
names, _ = decode(ext.get_data(), asn1Spec=GeneralNames())
for n in names:
name_string = n.getName()
if name_string == "dNSName":
ids.append(DNSPattern(n.getComponent().asOctets()))
elif name_string == "iPAddress":
ids.append(
IPAddressPattern.from_bytes(
n.getComponent().asOctets()
)
)
elif name_string == "uniformResourceIdentifier":
ids.append(URIPattern(n.getComponent().asOctets()))
elif name_string == "otherName":
comp = n.getComponent()
oid = comp.getComponentByPosition(0)
if oid == ID_ON_DNS_SRV:
srv, _ = decode(comp.getComponentByPosition(1))
if isinstance(srv, IA5String):
ids.append(SRVPattern(srv.asOctets()))
else: # pragma: nocover
raise CertificateError(
"Unexpected certificate content."
)
else: # pragma: nocover
pass
else: # pragma: nocover
pass
if not ids:
# https://tools.ietf.org/search/rfc6125#section-6.4.4
# A client MUST NOT seek a match for a reference identifier of CN-ID if
# the presented identifiers include a DNS-ID, SRV-ID, URI-ID, or any
# application-specific identifier types supported by the client.
components = [
c[1] for c in cert.get_subject().get_components() if c[0] == b"CN"
]
cn = next(iter(components), b"<not given>")
ids = [DNSPattern(c) for c in components]
warnings.warn(
"Certificate with CN '%s' has no `subjectAltName`, falling back "
"to check for a `commonName` for now. This feature is being "
"removed by major browsers and deprecated by RFC 2818. "
"service_identity will remove the support for it in mid-2018."
% (cn.decode("utf-8"),),
SubjectAltNameWarning,
stacklevel=2,
)
return ids