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# Wrapper module for _ssl, providing some additional facilities# implemented in Python. Written by Bill Janssen.
"""\
This module provides some more Pythonic support for SSL.
Object types:
SSLSocket -- subtype of socket.socket which does SSL over the socket
Exceptions:
SSLError -- exception raised for I/O errors
Functions:
cert_time_to_seconds -- convert time string used for certificate notBefore and notAfter functions to integer seconds past the Epoch (the time values returned from time.time())
fetch_server_certificate (HOST, PORT) -- fetch the certificate provided by the server running on HOST at port PORT. No validation of the certificate is performed.
Integer constants:
SSL_ERROR_ZERO_RETURNSSL_ERROR_WANT_READSSL_ERROR_WANT_WRITESSL_ERROR_WANT_X509_LOOKUPSSL_ERROR_SYSCALLSSL_ERROR_SSLSSL_ERROR_WANT_CONNECT
SSL_ERROR_EOFSSL_ERROR_INVALID_ERROR_CODE
The following group define certificate requirements that one side isallowing/requiring from the other side:
CERT_NONE - no certificates from the other side are required (or will be looked at if provided)CERT_OPTIONAL - certificates are not required, but if provided will be validated, and if validation fails, the connection will also failCERT_REQUIRED - certificates are required, and will be validated, and if validation fails, the connection will also fail
The following constants identify various SSL protocol variants:
PROTOCOL_SSLv2PROTOCOL_SSLv3PROTOCOL_SSLv23PROTOCOL_TLSv1"""
import textwrap
import _ssl # if we can't import it, let the error propagate
from _ssl import OPENSSL_VERSION_NUMBER, OPENSSL_VERSION_INFO, OPENSSL_VERSIONfrom _ssl import SSLErrorfrom _ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIREDfrom _ssl import RAND_status, RAND_egd, RAND_addfrom _ssl import \ SSL_ERROR_ZERO_RETURN, \ SSL_ERROR_WANT_READ, \ SSL_ERROR_WANT_WRITE, \ SSL_ERROR_WANT_X509_LOOKUP, \ SSL_ERROR_SYSCALL, \ SSL_ERROR_SSL, \ SSL_ERROR_WANT_CONNECT, \ SSL_ERROR_EOF, \ SSL_ERROR_INVALID_ERROR_CODEfrom _ssl import PROTOCOL_SSLv3, PROTOCOL_SSLv23, PROTOCOL_TLSv1_PROTOCOL_NAMES = { PROTOCOL_TLSv1: "TLSv1", PROTOCOL_SSLv23: "SSLv23", PROTOCOL_SSLv3: "SSLv3",}try: from _ssl import PROTOCOL_SSLv2 _SSLv2_IF_EXISTS = PROTOCOL_SSLv2except ImportError: _SSLv2_IF_EXISTS = Noneelse: _PROTOCOL_NAMES[PROTOCOL_SSLv2] = "SSLv2"
from socket import socket, _fileobject, _delegate_methods, error as socket_errorfrom socket import getnameinfo as _getnameinfoimport base64 # for DER-to-PEM translationimport errno
# Disable weak or insecure ciphers by default# (OpenSSL's default setting is 'DEFAULT:!aNULL:!eNULL')_DEFAULT_CIPHERS = 'DEFAULT:!aNULL:!eNULL:!LOW:!EXPORT:!SSLv2'
class SSLSocket(socket):
"""This class implements a subtype of socket.socket that wraps
the underlying OS socket in an SSL context when necessary, and provides read and write methods over that channel."""
def __init__(self, sock, keyfile=None, certfile=None, server_side=False, cert_reqs=CERT_NONE, ssl_version=PROTOCOL_SSLv23, ca_certs=None, do_handshake_on_connect=True, suppress_ragged_eofs=True, ciphers=None): socket.__init__(self, _sock=sock._sock) # The initializer for socket overrides the methods send(), recv(), etc. # in the instancce, which we don't need -- but we want to provide the # methods defined in SSLSocket. for attr in _delegate_methods: try: delattr(self, attr) except AttributeError: pass
if ciphers is None and ssl_version != _SSLv2_IF_EXISTS: ciphers = _DEFAULT_CIPHERS
if certfile and not keyfile: keyfile = certfile # see if it's connected try: socket.getpeername(self) except socket_error, e: if e.errno != errno.ENOTCONN: raise # no, no connection yet self._connected = False self._sslobj = None else: # yes, create the SSL object self._connected = True self._sslobj = _ssl.sslwrap(self._sock, server_side, keyfile, certfile, cert_reqs, ssl_version, ca_certs, ciphers) if do_handshake_on_connect: self.do_handshake() self.keyfile = keyfile self.certfile = certfile self.cert_reqs = cert_reqs self.ssl_version = ssl_version self.ca_certs = ca_certs self.ciphers = ciphers self.do_handshake_on_connect = do_handshake_on_connect self.suppress_ragged_eofs = suppress_ragged_eofs self._makefile_refs = 0
def read(self, len=1024):
"""Read up to LEN bytes and return them.
Return zero-length string on EOF."""
try: return self._sslobj.read(len) except SSLError, x: if x.args[0] == SSL_ERROR_EOF and self.suppress_ragged_eofs: return '' else: raise
def write(self, data):
"""Write DATA to the underlying SSL channel. Returns
number of bytes of DATA actually transmitted."""
return self._sslobj.write(data)
def getpeercert(self, binary_form=False):
"""Returns a formatted version of the data in the
certificate provided by the other end of the SSL channel. Return None if no certificate was provided, {} if a certificate was provided, but not validated."""
return self._sslobj.peer_certificate(binary_form)
def cipher(self):
if not self._sslobj: return None else: return self._sslobj.cipher()
def send(self, data, flags=0): if self._sslobj: if flags != 0: raise ValueError( "non-zero flags not allowed in calls to send() on %s" % self.__class__) while True: try: v = self._sslobj.write(data) except SSLError, x: if x.args[0] == SSL_ERROR_WANT_READ: return 0 elif x.args[0] == SSL_ERROR_WANT_WRITE: return 0 else: raise else: return v else: return self._sock.send(data, flags)
def sendto(self, data, flags_or_addr, addr=None): if self._sslobj: raise ValueError("sendto not allowed on instances of %s" % self.__class__) elif addr is None: return self._sock.sendto(data, flags_or_addr) else: return self._sock.sendto(data, flags_or_addr, addr)
def sendall(self, data, flags=0): if self._sslobj: if flags != 0: raise ValueError( "non-zero flags not allowed in calls to sendall() on %s" % self.__class__) amount = len(data) count = 0 while (count < amount): v = self.send(data[count:]) count += v return amount else: return socket.sendall(self, data, flags)
def recv(self, buflen=1024, flags=0): if self._sslobj: if flags != 0: raise ValueError( "non-zero flags not allowed in calls to recv() on %s" % self.__class__) return self.read(buflen) else: return self._sock.recv(buflen, flags)
def recv_into(self, buffer, nbytes=None, flags=0): if buffer and (nbytes is None): nbytes = len(buffer) elif nbytes is None: nbytes = 1024 if self._sslobj: if flags != 0: raise ValueError( "non-zero flags not allowed in calls to recv_into() on %s" % self.__class__) tmp_buffer = self.read(nbytes) v = len(tmp_buffer) buffer[:v] = tmp_buffer return v else: return self._sock.recv_into(buffer, nbytes, flags)
def recvfrom(self, buflen=1024, flags=0): if self._sslobj: raise ValueError("recvfrom not allowed on instances of %s" % self.__class__) else: return self._sock.recvfrom(buflen, flags)
def recvfrom_into(self, buffer, nbytes=None, flags=0): if self._sslobj: raise ValueError("recvfrom_into not allowed on instances of %s" % self.__class__) else: return self._sock.recvfrom_into(buffer, nbytes, flags)
def pending(self): if self._sslobj: return self._sslobj.pending() else: return 0
def unwrap(self): if self._sslobj: s = self._sslobj.shutdown() self._sslobj = None return s else: raise ValueError("No SSL wrapper around " + str(self))
def shutdown(self, how): self._sslobj = None socket.shutdown(self, how)
def close(self): if self._makefile_refs < 1: self._sslobj = None socket.close(self) else: self._makefile_refs -= 1
def do_handshake(self):
"""Perform a TLS/SSL handshake."""
self._sslobj.do_handshake()
def _real_connect(self, addr, return_errno): # Here we assume that the socket is client-side, and not # connected at the time of the call. We connect it, then wrap it. if self._connected: raise ValueError("attempt to connect already-connected SSLSocket!") self._sslobj = _ssl.sslwrap(self._sock, False, self.keyfile, self.certfile, self.cert_reqs, self.ssl_version, self.ca_certs, self.ciphers) try: socket.connect(self, addr) if self.do_handshake_on_connect: self.do_handshake() except socket_error as e: if return_errno: return e.errno else: self._sslobj = None raise e self._connected = True return 0
def connect(self, addr): """Connects to remote ADDR, and then wraps the connection in
an SSL channel."""
self._real_connect(addr, False)
def connect_ex(self, addr): """Connects to remote ADDR, and then wraps the connection in
an SSL channel."""
return self._real_connect(addr, True)
def accept(self):
"""Accepts a new connection from a remote client, and returns
a tuple containing that new connection wrapped with a server-side SSL channel, and the address of the remote client."""
newsock, addr = socket.accept(self) return (SSLSocket(newsock, keyfile=self.keyfile, certfile=self.certfile, server_side=True, cert_reqs=self.cert_reqs, ssl_version=self.ssl_version, ca_certs=self.ca_certs, ciphers=self.ciphers, do_handshake_on_connect=self.do_handshake_on_connect, suppress_ragged_eofs=self.suppress_ragged_eofs), addr)
def makefile(self, mode='r', bufsize=-1):
"""Make and return a file-like object that
works with the SSL connection. Just use the code from the socket module."""
self._makefile_refs += 1 # close=True so as to decrement the reference count when done with # the file-like object. return _fileobject(self, mode, bufsize, close=True)
def wrap_socket(sock, keyfile=None, certfile=None, server_side=False, cert_reqs=CERT_NONE, ssl_version=PROTOCOL_SSLv23, ca_certs=None, do_handshake_on_connect=True, suppress_ragged_eofs=True, ciphers=None):
return SSLSocket(sock, keyfile=keyfile, certfile=certfile, server_side=server_side, cert_reqs=cert_reqs, ssl_version=ssl_version, ca_certs=ca_certs, do_handshake_on_connect=do_handshake_on_connect, suppress_ragged_eofs=suppress_ragged_eofs, ciphers=ciphers)
# some utility functions
def cert_time_to_seconds(cert_time):
"""Takes a date-time string in standard ASN1_print form
("MON DAY 24HOUR:MINUTE:SEC YEAR TIMEZONE") and return a Python time value in seconds past the epoch."""
import time return time.mktime(time.strptime(cert_time, "%b %d %H:%M:%S %Y GMT"))
PEM_HEADER = "-----BEGIN CERTIFICATE-----"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."""
if hasattr(base64, 'standard_b64encode'): # preferred because older API gets line-length wrong f = base64.standard_b64encode(der_cert_bytes) return (PEM_HEADER + '\n' + textwrap.fill(f, 64) + '\n' + PEM_FOOTER + '\n') else: return (PEM_HEADER + '\n' + base64.encodestring(der_cert_bytes) + 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.decodestring(d)
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>')
# a replacement for the old socket.ssl function
def sslwrap_simple(sock, keyfile=None, certfile=None):
"""A replacement for the old socket.ssl function. Designed
for compability with Python 2.5 and earlier. Will disappear in Python 3.0."""
if hasattr(sock, "_sock"): sock = sock._sock
ssl_sock = _ssl.sslwrap(sock, 0, keyfile, certfile, CERT_NONE, PROTOCOL_SSLv23, None) try: sock.getpeername() except socket_error: # no, no connection yet pass else: # yes, do the handshake ssl_sock.do_handshake()
return ssl_sock
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