554 lines
17 KiB
Python
554 lines
17 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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"""\
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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 _ssl # if we can't import it, let the error propagate
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from _ssl import SSLError
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from _ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED
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from _ssl import PROTOCOL_SSLv2, PROTOCOL_SSLv3, PROTOCOL_SSLv23, PROTOCOL_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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from socket import socket
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from socket import getnameinfo as _getnameinfo
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import base64 # for DER-to-PEM translation
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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, 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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socket.__init__(self, _sock=sock._sock)
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if certfile and not keyfile:
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keyfile = certfile
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# see if it's connected
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try:
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socket.getpeername(self)
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except:
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# no, no connection yet
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self._sslobj = None
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else:
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# yes, create the SSL object
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self._sslobj = _ssl.sslwrap(self._sock, server_side,
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keyfile, certfile,
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cert_reqs, ssl_version, ca_certs)
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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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def read(self, len=1024):
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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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return self._sslobj.read(len)
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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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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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return self._sslobj.peer_certificate(binary_form)
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def cipher (self):
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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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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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return self._sslobj.write(data)
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else:
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return socket.send(self, data, flags)
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def send_to (self, data, addr, flags=0):
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if self._sslobj:
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raise ValueError("send_to not allowed on instances of %s" %
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self.__class__)
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else:
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return socket.send_to(self, data, addr, flags)
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def sendall (self, data, flags=0):
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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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return self._sslobj.write(data)
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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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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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return self._sslobj.read(data, buflen)
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else:
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return socket.recv(self, buflen, flags)
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def recv_from (self, addr, buflen=1024, flags=0):
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if self._sslobj:
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raise ValueError("recv_from not allowed on instances of %s" %
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self.__class__)
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else:
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return socket.recv_from(self, addr, buflen, flags)
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def shutdown(self, how):
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self._sslobj = None
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socket.shutdown(self, how)
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def close(self):
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self._sslobj = None
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socket.close(self)
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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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# 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._sslobj:
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raise ValueError("attempt to connect already-connected SSLSocket!")
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socket.connect(self, addr)
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self._sslobj = _ssl.sslwrap(self._sock, False, self.keyfile, self.certfile,
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self.cert_reqs, self.ssl_version,
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self.ca_certs)
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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(newsock, True, self.keyfile, self.certfile,
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self.cert_reqs, self.ssl_version,
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self.ca_certs), addr)
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def makefile(self, mode='r', bufsize=-1):
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"""Ouch. Need to make and return a file-like object that
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works with the SSL connection."""
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if self._sslobj:
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return SSLFileStream(self._sslobj, mode, bufsize)
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else:
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return socket.makefile(self, mode, bufsize)
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class SSLFileStream:
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"""A class to simulate a file stream on top of a socket.
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Most of this is just lifted from the socket module, and
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adjusted to work with an SSL stream instead of a socket."""
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default_bufsize = 8192
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name = "<SSL stream>"
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__slots__ = ["mode", "bufsize", "softspace",
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# "closed" is a property, see below
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"_sslobj", "_rbufsize", "_wbufsize", "_rbuf", "_wbuf",
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"_close", "_fileno"]
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def __init__(self, sslobj, mode='rb', bufsize=-1, close=False):
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self._sslobj = sslobj
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self.mode = mode # Not actually used in this version
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if bufsize < 0:
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bufsize = self.default_bufsize
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self.bufsize = bufsize
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self.softspace = False
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if bufsize == 0:
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self._rbufsize = 1
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elif bufsize == 1:
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self._rbufsize = self.default_bufsize
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else:
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self._rbufsize = bufsize
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self._wbufsize = bufsize
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self._rbuf = "" # A string
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self._wbuf = [] # A list of strings
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self._close = close
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self._fileno = -1
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def _getclosed(self):
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return self._sslobj is None
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closed = property(_getclosed, doc="True if the file is closed")
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def fileno(self):
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return self._fileno
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def close(self):
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try:
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if self._sslobj:
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self.flush()
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finally:
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if self._close and self._sslobj:
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self._sslobj.close()
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self._sslobj = None
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def __del__(self):
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try:
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self.close()
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except:
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# close() may fail if __init__ didn't complete
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pass
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def flush(self):
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if self._wbuf:
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buffer = "".join(self._wbuf)
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self._wbuf = []
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count = 0
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while (count < len(buffer)):
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written = self._sslobj.write(buffer)
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count += written
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buffer = buffer[written:]
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def write(self, data):
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data = str(data) # XXX Should really reject non-string non-buffers
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if not data:
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return
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self._wbuf.append(data)
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if (self._wbufsize == 0 or
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self._wbufsize == 1 and '\n' in data or
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self._get_wbuf_len() >= self._wbufsize):
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self.flush()
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def writelines(self, list):
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# XXX We could do better here for very long lists
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# XXX Should really reject non-string non-buffers
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self._wbuf.extend(filter(None, map(str, list)))
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if (self._wbufsize <= 1 or
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self._get_wbuf_len() >= self._wbufsize):
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self.flush()
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def _get_wbuf_len(self):
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buf_len = 0
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for x in self._wbuf:
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buf_len += len(x)
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return buf_len
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def read(self, size=-1):
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data = self._rbuf
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if size < 0:
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# Read until EOF
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buffers = []
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if data:
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buffers.append(data)
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self._rbuf = ""
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if self._rbufsize <= 1:
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recv_size = self.default_bufsize
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else:
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recv_size = self._rbufsize
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while True:
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data = self._sslobj.read(recv_size)
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if not data:
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break
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buffers.append(data)
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return "".join(buffers)
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else:
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# Read until size bytes or EOF seen, whichever comes first
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buf_len = len(data)
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if buf_len >= size:
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self._rbuf = data[size:]
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return data[:size]
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buffers = []
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if data:
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buffers.append(data)
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self._rbuf = ""
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while True:
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left = size - buf_len
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recv_size = max(self._rbufsize, left)
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data = self._sslobj.read(recv_size)
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if not data:
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break
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buffers.append(data)
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n = len(data)
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if n >= left:
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self._rbuf = data[left:]
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buffers[-1] = data[:left]
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break
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buf_len += n
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return "".join(buffers)
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def readline(self, size=-1):
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data = self._rbuf
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if size < 0:
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# Read until \n or EOF, whichever comes first
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if self._rbufsize <= 1:
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# Speed up unbuffered case
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assert data == ""
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buffers = []
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while data != "\n":
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data = self._sslobj.read(1)
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if not data:
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break
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buffers.append(data)
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return "".join(buffers)
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nl = data.find('\n')
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if nl >= 0:
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nl += 1
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self._rbuf = data[nl:]
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return data[:nl]
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buffers = []
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if data:
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buffers.append(data)
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self._rbuf = ""
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while True:
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data = self._sslobj.read(self._rbufsize)
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if not data:
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break
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buffers.append(data)
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nl = data.find('\n')
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if nl >= 0:
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nl += 1
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self._rbuf = data[nl:]
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buffers[-1] = data[:nl]
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break
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return "".join(buffers)
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else:
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# Read until size bytes or \n or EOF seen, whichever comes first
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nl = data.find('\n', 0, size)
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if nl >= 0:
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nl += 1
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self._rbuf = data[nl:]
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return data[:nl]
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buf_len = len(data)
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if buf_len >= size:
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self._rbuf = data[size:]
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return data[:size]
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buffers = []
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if data:
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buffers.append(data)
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self._rbuf = ""
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while True:
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data = self._sslobj.read(self._rbufsize)
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if not data:
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break
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buffers.append(data)
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left = size - buf_len
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nl = data.find('\n', 0, left)
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if nl >= 0:
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nl += 1
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self._rbuf = data[nl:]
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buffers[-1] = data[:nl]
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break
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n = len(data)
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if n >= left:
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self._rbuf = data[left:]
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buffers[-1] = data[:left]
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break
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buf_len += n
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return "".join(buffers)
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def readlines(self, sizehint=0):
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total = 0
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list = []
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while True:
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line = self.readline()
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if not line:
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break
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list.append(line)
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total += len(line)
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if sizehint and total >= sizehint:
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break
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return list
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# Iterator protocols
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def __iter__(self):
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return self
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def next(self):
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line = self.readline()
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if not line:
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raise StopIteration
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return line
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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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return SSLSocket(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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# 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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def DER_cert_to_PEM_cert(der_cert_bytes):
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"""Takes a certificate in binary DER format and returns the
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PEM version of it as a string."""
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if hasattr(base64, 'standard_b64encode'):
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# preferred because older API gets line-length wrong
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f = base64.standard_b64encode(der_cert_bytes)
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return (PEM_HEADER + '\n' +
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textwrap.fill(f, 64) +
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PEM_FOOTER + '\n')
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else:
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return (PEM_HEADER + '\n' +
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base64.encodestring(der_cert_bytes) +
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PEM_FOOTER + '\n')
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def PEM_cert_to_DER_cert(pem_cert_string):
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"""Takes a certificate in ASCII PEM format and returns the
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DER-encoded version of it as a byte sequence"""
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if not pem_cert_string.startswith(PEM_HEADER):
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raise ValueError("Invalid PEM encoding; must start with %s"
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% PEM_HEADER)
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if not pem_cert_string.strip().endswith(PEM_FOOTER):
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raise ValueError("Invalid PEM encoding; must end with %s"
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% PEM_FOOTER)
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d = pem_cert_string.strip()[len(PEM_HEADER):-len(PEM_FOOTER)]
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return base64.decodestring(d)
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def get_server_certificate (addr, ssl_version=PROTOCOL_SSLv3, ca_certs=None):
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"""Retrieve the certificate from the server at the specified address,
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and return it as a PEM-encoded string.
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If 'ca_certs' is specified, validate the server cert against it.
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If 'ssl_version' is specified, use it in the connection attempt."""
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host, port = addr
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if (ca_certs is not None):
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cert_reqs = CERT_REQUIRED
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else:
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cert_reqs = CERT_NONE
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s = wrap_socket(socket(), ssl_version=ssl_version,
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cert_reqs=cert_reqs, ca_certs=ca_certs)
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s.connect(addr)
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dercert = s.getpeercert(True)
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s.close()
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return DER_cert_to_PEM_cert(dercert)
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def get_protocol_name (protocol_code):
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if protocol_code == PROTOCOL_TLSv1:
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return "TLSv1"
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elif protocol_code == PROTOCOL_SSLv23:
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return "SSLv23"
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elif protocol_code == PROTOCOL_SSLv2:
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return "SSLv2"
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elif protocol_code == PROTOCOL_SSLv3:
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return "SSLv3"
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else:
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return "<unknown>"
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# a replacement for the old socket.ssl function
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def sslwrap_simple (sock, keyfile=None, certfile=None):
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"""A replacement for the old socket.ssl function. Designed
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for compability with Python 2.5 and earlier. Will disappear in
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Python 3.0."""
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return _ssl.sslwrap(sock._sock, 0, keyfile, certfile, CERT_NONE,
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PROTOCOL_SSLv23, None)
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