578 lines
20 KiB
Python
578 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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_SSLv2_IF_EXISTS = PROTOCOL_SSLv2
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except ImportError:
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_SSLv2_IF_EXISTS = None
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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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# Disable weak or insecure ciphers by default
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# (OpenSSL's default setting is 'DEFAULT:!aNULL:!eNULL')
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_DEFAULT_CIPHERS = 'DEFAULT:!aNULL:!eNULL:!LOW:!EXPORT:!SSLv2'
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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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self = _SSLContext.__new__(cls, protocol)
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if protocol != _SSLv2_IF_EXISTS:
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self.set_ciphers(_DEFAULT_CIPHERS)
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return self
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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."""
|
|
|
|
import time
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return time.mktime(time.strptime(cert_time, "%b %d %H:%M:%S %Y GMT"))
|
|
|
|
PEM_HEADER = "-----BEGIN CERTIFICATE-----"
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|
PEM_FOOTER = "-----END CERTIFICATE-----"
|
|
|
|
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."""
|
|
|
|
f = str(base64.standard_b64encode(der_cert_bytes), 'ASCII', 'strict')
|
|
return (PEM_HEADER + '\n' +
|
|
textwrap.fill(f, 64) + '\n' +
|
|
PEM_FOOTER + '\n')
|
|
|
|
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"""
|
|
|
|
if not pem_cert_string.startswith(PEM_HEADER):
|
|
raise ValueError("Invalid PEM encoding; must start with %s"
|
|
% PEM_HEADER)
|
|
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>')
|