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b9ac25d1c3
reset, check the version of the OpenSSL headers Python was compiled against, rather than the runtime version of the OpenSSL library.
570 lines
20 KiB
Python
570 lines
20 KiB
Python
# Wrapper module for _ssl, providing some additional facilities
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# implemented in Python. Written by Bill Janssen.
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"""This module provides some more Pythonic support for SSL.
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Object types:
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SSLSocket -- subtype of socket.socket which does SSL over the socket
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Exceptions:
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SSLError -- exception raised for I/O errors
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Functions:
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cert_time_to_seconds -- convert time string used for certificate
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notBefore and notAfter functions to integer
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seconds past the Epoch (the time values
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returned from time.time())
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fetch_server_certificate (HOST, PORT) -- fetch the certificate provided
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by the server running on HOST at port PORT. No
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validation of the certificate is performed.
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Integer constants:
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SSL_ERROR_ZERO_RETURN
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SSL_ERROR_WANT_READ
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SSL_ERROR_WANT_WRITE
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SSL_ERROR_WANT_X509_LOOKUP
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SSL_ERROR_SYSCALL
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SSL_ERROR_SSL
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SSL_ERROR_WANT_CONNECT
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SSL_ERROR_EOF
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SSL_ERROR_INVALID_ERROR_CODE
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The following group define certificate requirements that one side is
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allowing/requiring from the other side:
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CERT_NONE - no certificates from the other side are required (or will
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be looked at if provided)
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CERT_OPTIONAL - certificates are not required, but if provided will be
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validated, and if validation fails, the connection will
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also fail
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CERT_REQUIRED - certificates are required, and will be validated, and
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if validation fails, the connection will also fail
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The following constants identify various SSL protocol variants:
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PROTOCOL_SSLv2
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PROTOCOL_SSLv3
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PROTOCOL_SSLv23
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PROTOCOL_TLSv1
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"""
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import textwrap
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import re
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import _ssl # if we can't import it, let the error propagate
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from _ssl import OPENSSL_VERSION_NUMBER, OPENSSL_VERSION_INFO, OPENSSL_VERSION
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from _ssl import _SSLContext, SSLError
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from _ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED
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from _ssl import OP_ALL, OP_NO_SSLv2, OP_NO_SSLv3, OP_NO_TLSv1
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from _ssl import RAND_status, RAND_egd, RAND_add
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from _ssl import (
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SSL_ERROR_ZERO_RETURN,
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SSL_ERROR_WANT_READ,
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SSL_ERROR_WANT_WRITE,
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SSL_ERROR_WANT_X509_LOOKUP,
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SSL_ERROR_SYSCALL,
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SSL_ERROR_SSL,
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SSL_ERROR_WANT_CONNECT,
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SSL_ERROR_EOF,
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SSL_ERROR_INVALID_ERROR_CODE,
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)
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from _ssl import HAS_SNI
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from _ssl import PROTOCOL_SSLv3, PROTOCOL_SSLv23, PROTOCOL_TLSv1
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from _ssl import _OPENSSL_API_VERSION
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_PROTOCOL_NAMES = {
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PROTOCOL_TLSv1: "TLSv1",
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PROTOCOL_SSLv23: "SSLv23",
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PROTOCOL_SSLv3: "SSLv3",
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}
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try:
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from _ssl import PROTOCOL_SSLv2
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except ImportError:
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pass
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else:
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_PROTOCOL_NAMES[PROTOCOL_SSLv2] = "SSLv2"
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from socket import getnameinfo as _getnameinfo
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from socket import error as socket_error
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from socket import socket, AF_INET, SOCK_STREAM
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import base64 # for DER-to-PEM translation
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import traceback
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import errno
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class CertificateError(ValueError):
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pass
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def _dnsname_to_pat(dn):
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pats = []
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for frag in dn.split(r'.'):
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if frag == '*':
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# When '*' is a fragment by itself, it matches a non-empty dotless
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# fragment.
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pats.append('[^.]+')
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else:
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# Otherwise, '*' matches any dotless fragment.
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frag = re.escape(frag)
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pats.append(frag.replace(r'\*', '[^.]*'))
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return re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
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def match_hostname(cert, hostname):
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"""Verify that *cert* (in decoded format as returned by
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SSLSocket.getpeercert()) matches the *hostname*. RFC 2818 rules
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are mostly followed, but IP addresses are not accepted for *hostname*.
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CertificateError is raised on failure. On success, the function
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returns nothing.
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"""
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if not cert:
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raise ValueError("empty or no certificate")
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dnsnames = []
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san = cert.get('subjectAltName', ())
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for key, value in san:
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if key == 'DNS':
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if _dnsname_to_pat(value).match(hostname):
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return
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dnsnames.append(value)
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if not dnsnames:
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# The subject is only checked when there is no dNSName entry
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# in subjectAltName
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for sub in cert.get('subject', ()):
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for key, value in sub:
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# XXX according to RFC 2818, the most specific Common Name
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# must be used.
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if key == 'commonName':
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if _dnsname_to_pat(value).match(hostname):
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return
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dnsnames.append(value)
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if len(dnsnames) > 1:
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raise CertificateError("hostname %r "
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"doesn't match either of %s"
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% (hostname, ', '.join(map(repr, dnsnames))))
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elif len(dnsnames) == 1:
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raise CertificateError("hostname %r "
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"doesn't match %r"
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% (hostname, dnsnames[0]))
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else:
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raise CertificateError("no appropriate commonName or "
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"subjectAltName fields were found")
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class SSLContext(_SSLContext):
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"""An SSLContext holds various SSL-related configuration options and
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data, such as certificates and possibly a private key."""
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__slots__ = ('protocol',)
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def __new__(cls, protocol, *args, **kwargs):
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return _SSLContext.__new__(cls, protocol)
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def __init__(self, protocol):
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self.protocol = protocol
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def wrap_socket(self, sock, server_side=False,
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do_handshake_on_connect=True,
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suppress_ragged_eofs=True,
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server_hostname=None):
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return SSLSocket(sock=sock, server_side=server_side,
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do_handshake_on_connect=do_handshake_on_connect,
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suppress_ragged_eofs=suppress_ragged_eofs,
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server_hostname=server_hostname,
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_context=self)
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class SSLSocket(socket):
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"""This class implements a subtype of socket.socket that wraps
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the underlying OS socket in an SSL context when necessary, and
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provides read and write methods over that channel."""
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def __init__(self, sock=None, keyfile=None, certfile=None,
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server_side=False, cert_reqs=CERT_NONE,
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ssl_version=PROTOCOL_SSLv23, ca_certs=None,
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do_handshake_on_connect=True,
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family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None,
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suppress_ragged_eofs=True, ciphers=None,
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server_hostname=None,
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_context=None):
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if _context:
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self.context = _context
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else:
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if server_side and not certfile:
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raise ValueError("certfile must be specified for server-side "
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"operations")
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if keyfile and not certfile:
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raise ValueError("certfile must be specified")
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if certfile and not keyfile:
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keyfile = certfile
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self.context = SSLContext(ssl_version)
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self.context.verify_mode = cert_reqs
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if ca_certs:
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self.context.load_verify_locations(ca_certs)
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if certfile:
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self.context.load_cert_chain(certfile, keyfile)
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if ciphers:
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self.context.set_ciphers(ciphers)
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self.keyfile = keyfile
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self.certfile = certfile
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self.cert_reqs = cert_reqs
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self.ssl_version = ssl_version
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self.ca_certs = ca_certs
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self.ciphers = ciphers
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if server_side and server_hostname:
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raise ValueError("server_hostname can only be specified "
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"in client mode")
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self.server_side = server_side
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self.server_hostname = server_hostname
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self.do_handshake_on_connect = do_handshake_on_connect
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self.suppress_ragged_eofs = suppress_ragged_eofs
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connected = False
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if sock is not None:
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socket.__init__(self,
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family=sock.family,
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type=sock.type,
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proto=sock.proto,
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fileno=sock.fileno())
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self.settimeout(sock.gettimeout())
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# see if it's connected
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try:
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sock.getpeername()
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except socket_error as e:
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if e.errno != errno.ENOTCONN:
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raise
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else:
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connected = True
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sock.detach()
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elif fileno is not None:
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socket.__init__(self, fileno=fileno)
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else:
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socket.__init__(self, family=family, type=type, proto=proto)
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self._closed = False
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self._sslobj = None
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self._connected = connected
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if connected:
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# create the SSL object
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try:
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self._sslobj = self.context._wrap_socket(self, server_side,
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server_hostname)
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if do_handshake_on_connect:
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timeout = self.gettimeout()
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if timeout == 0.0:
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# non-blocking
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raise ValueError("do_handshake_on_connect should not be specified for non-blocking sockets")
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self.do_handshake()
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except socket_error as x:
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self.close()
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raise x
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def dup(self):
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raise NotImplemented("Can't dup() %s instances" %
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self.__class__.__name__)
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def _checkClosed(self, msg=None):
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# raise an exception here if you wish to check for spurious closes
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pass
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def read(self, len=0, buffer=None):
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"""Read up to LEN bytes and return them.
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Return zero-length string on EOF."""
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self._checkClosed()
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try:
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if buffer is not None:
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v = self._sslobj.read(len, buffer)
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else:
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v = self._sslobj.read(len or 1024)
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return v
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except SSLError as x:
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if x.args[0] == SSL_ERROR_EOF and self.suppress_ragged_eofs:
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if buffer is not None:
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return 0
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else:
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return b''
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else:
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raise
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def write(self, data):
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"""Write DATA to the underlying SSL channel. Returns
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number of bytes of DATA actually transmitted."""
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self._checkClosed()
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return self._sslobj.write(data)
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def getpeercert(self, binary_form=False):
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"""Returns a formatted version of the data in the
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certificate provided by the other end of the SSL channel.
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Return None if no certificate was provided, {} if a
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certificate was provided, but not validated."""
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self._checkClosed()
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return self._sslobj.peer_certificate(binary_form)
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def cipher(self):
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self._checkClosed()
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if not self._sslobj:
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return None
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else:
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return self._sslobj.cipher()
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def send(self, data, flags=0):
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self._checkClosed()
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if self._sslobj:
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if flags != 0:
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raise ValueError(
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"non-zero flags not allowed in calls to send() on %s" %
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self.__class__)
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while True:
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try:
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v = self._sslobj.write(data)
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except SSLError as x:
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if x.args[0] == SSL_ERROR_WANT_READ:
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return 0
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elif x.args[0] == SSL_ERROR_WANT_WRITE:
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return 0
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else:
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raise
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else:
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return v
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else:
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return socket.send(self, data, flags)
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def sendto(self, data, flags_or_addr, addr=None):
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self._checkClosed()
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if self._sslobj:
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raise ValueError("sendto not allowed on instances of %s" %
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self.__class__)
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elif addr is None:
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return socket.sendto(self, data, flags_or_addr)
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else:
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return socket.sendto(self, data, flags_or_addr, addr)
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def sendall(self, data, flags=0):
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self._checkClosed()
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if self._sslobj:
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if flags != 0:
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raise ValueError(
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"non-zero flags not allowed in calls to sendall() on %s" %
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self.__class__)
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amount = len(data)
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count = 0
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while (count < amount):
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v = self.send(data[count:])
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count += v
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return amount
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else:
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return socket.sendall(self, data, flags)
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def recv(self, buflen=1024, flags=0):
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self._checkClosed()
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if self._sslobj:
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if flags != 0:
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raise ValueError(
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"non-zero flags not allowed in calls to recv() on %s" %
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self.__class__)
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return self.read(buflen)
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else:
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return socket.recv(self, buflen, flags)
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def recv_into(self, buffer, nbytes=None, flags=0):
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self._checkClosed()
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if buffer and (nbytes is None):
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nbytes = len(buffer)
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elif nbytes is None:
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nbytes = 1024
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if self._sslobj:
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if flags != 0:
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raise ValueError(
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"non-zero flags not allowed in calls to recv_into() on %s" %
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self.__class__)
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return self.read(nbytes, buffer)
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else:
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return socket.recv_into(self, buffer, nbytes, flags)
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def recvfrom(self, buflen=1024, flags=0):
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self._checkClosed()
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if self._sslobj:
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raise ValueError("recvfrom not allowed on instances of %s" %
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self.__class__)
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else:
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return socket.recvfrom(self, buflen, flags)
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def recvfrom_into(self, buffer, nbytes=None, flags=0):
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self._checkClosed()
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if self._sslobj:
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raise ValueError("recvfrom_into not allowed on instances of %s" %
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self.__class__)
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else:
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return socket.recvfrom_into(self, buffer, nbytes, flags)
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def pending(self):
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self._checkClosed()
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if self._sslobj:
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return self._sslobj.pending()
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else:
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return 0
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def shutdown(self, how):
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self._checkClosed()
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self._sslobj = None
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socket.shutdown(self, how)
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def unwrap(self):
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if self._sslobj:
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s = self._sslobj.shutdown()
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self._sslobj = None
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return s
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else:
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raise ValueError("No SSL wrapper around " + str(self))
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def _real_close(self):
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self._sslobj = None
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# self._closed = True
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socket._real_close(self)
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def do_handshake(self, block=False):
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"""Perform a TLS/SSL handshake."""
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timeout = self.gettimeout()
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try:
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if timeout == 0.0 and block:
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self.settimeout(None)
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self._sslobj.do_handshake()
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finally:
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self.settimeout(timeout)
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def _real_connect(self, addr, connect_ex):
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if self.server_side:
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raise ValueError("can't connect in server-side mode")
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# Here we assume that the socket is client-side, and not
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# connected at the time of the call. We connect it, then wrap it.
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if self._connected:
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raise ValueError("attempt to connect already-connected SSLSocket!")
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self._sslobj = self.context._wrap_socket(self, False, self.server_hostname)
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try:
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if connect_ex:
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rc = socket.connect_ex(self, addr)
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else:
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rc = None
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socket.connect(self, addr)
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if not rc:
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if self.do_handshake_on_connect:
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self.do_handshake()
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self._connected = True
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return rc
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except socket_error:
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self._sslobj = None
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raise
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def connect(self, addr):
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"""Connects to remote ADDR, and then wraps the connection in
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an SSL channel."""
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self._real_connect(addr, False)
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def connect_ex(self, addr):
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"""Connects to remote ADDR, and then wraps the connection in
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an SSL channel."""
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return self._real_connect(addr, True)
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def accept(self):
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"""Accepts a new connection from a remote client, and returns
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a tuple containing that new connection wrapped with a server-side
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SSL channel, and the address of the remote client."""
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newsock, addr = socket.accept(self)
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return (SSLSocket(sock=newsock,
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keyfile=self.keyfile, certfile=self.certfile,
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server_side=True,
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cert_reqs=self.cert_reqs,
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ssl_version=self.ssl_version,
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ca_certs=self.ca_certs,
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ciphers=self.ciphers,
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do_handshake_on_connect=
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self.do_handshake_on_connect),
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addr)
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def __del__(self):
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# sys.stderr.write("__del__ on %s\n" % repr(self))
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self._real_close()
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def wrap_socket(sock, keyfile=None, certfile=None,
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server_side=False, cert_reqs=CERT_NONE,
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ssl_version=PROTOCOL_SSLv23, ca_certs=None,
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do_handshake_on_connect=True,
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suppress_ragged_eofs=True, ciphers=None):
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return SSLSocket(sock=sock, keyfile=keyfile, certfile=certfile,
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server_side=server_side, cert_reqs=cert_reqs,
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ssl_version=ssl_version, ca_certs=ca_certs,
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do_handshake_on_connect=do_handshake_on_connect,
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suppress_ragged_eofs=suppress_ragged_eofs,
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ciphers=ciphers)
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# some utility functions
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def cert_time_to_seconds(cert_time):
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"""Takes a date-time string in standard ASN1_print form
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("MON DAY 24HOUR:MINUTE:SEC YEAR TIMEZONE") and return
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a Python time value in seconds past the epoch."""
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import time
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return time.mktime(time.strptime(cert_time, "%b %d %H:%M:%S %Y GMT"))
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PEM_HEADER = "-----BEGIN CERTIFICATE-----"
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PEM_FOOTER = "-----END CERTIFICATE-----"
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|
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def DER_cert_to_PEM_cert(der_cert_bytes):
|
|
"""Takes a certificate in binary DER format and returns the
|
|
PEM version of it as a string."""
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|
|
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f = str(base64.standard_b64encode(der_cert_bytes), 'ASCII', 'strict')
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return (PEM_HEADER + '\n' +
|
|
textwrap.fill(f, 64) + '\n' +
|
|
PEM_FOOTER + '\n')
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|
|
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def PEM_cert_to_DER_cert(pem_cert_string):
|
|
"""Takes a certificate in ASCII PEM format and returns the
|
|
DER-encoded version of it as a byte sequence"""
|
|
|
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if not pem_cert_string.startswith(PEM_HEADER):
|
|
raise ValueError("Invalid PEM encoding; must start with %s"
|
|
% PEM_HEADER)
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|
if not pem_cert_string.strip().endswith(PEM_FOOTER):
|
|
raise ValueError("Invalid PEM encoding; must end with %s"
|
|
% PEM_FOOTER)
|
|
d = pem_cert_string.strip()[len(PEM_HEADER):-len(PEM_FOOTER)]
|
|
return base64.decodebytes(d.encode('ASCII', 'strict'))
|
|
|
|
def get_server_certificate(addr, ssl_version=PROTOCOL_SSLv3, ca_certs=None):
|
|
"""Retrieve the certificate from the server at the specified address,
|
|
and return it as a PEM-encoded string.
|
|
If 'ca_certs' is specified, validate the server cert against it.
|
|
If 'ssl_version' is specified, use it in the connection attempt."""
|
|
|
|
host, port = addr
|
|
if (ca_certs is not None):
|
|
cert_reqs = CERT_REQUIRED
|
|
else:
|
|
cert_reqs = CERT_NONE
|
|
s = wrap_socket(socket(), ssl_version=ssl_version,
|
|
cert_reqs=cert_reqs, ca_certs=ca_certs)
|
|
s.connect(addr)
|
|
dercert = s.getpeercert(True)
|
|
s.close()
|
|
return DER_cert_to_PEM_cert(dercert)
|
|
|
|
def get_protocol_name(protocol_code):
|
|
return _PROTOCOL_NAMES.get(protocol_code, '<unknown>')
|