cpython/Lib/ssl.py

554 lines
17 KiB
Python

# 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_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_CODE
The following group define certificate requirements that one side is
allowing/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 fail
CERT_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_SSLv2
PROTOCOL_SSLv3
PROTOCOL_SSLv23
PROTOCOL_TLSv1
"""
import os, sys, textwrap
import _ssl # if we can't import it, let the error propagate
from _ssl import SSLError
from _ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED
from _ssl import PROTOCOL_SSLv2, PROTOCOL_SSLv3, PROTOCOL_SSLv23, PROTOCOL_TLSv1
from _ssl import RAND_status, RAND_egd, RAND_add
from _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_CODE
from socket import socket
from socket import getnameinfo as _getnameinfo
import base64 # for DER-to-PEM translation
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):
socket.__init__(self, _sock=sock._sock)
if certfile and not keyfile:
keyfile = certfile
# see if it's connected
try:
socket.getpeername(self)
except:
# no, no connection yet
self._sslobj = None
else:
# yes, create the SSL object
self._sslobj = _ssl.sslwrap(self._sock, server_side,
keyfile, certfile,
cert_reqs, ssl_version, ca_certs)
self.keyfile = keyfile
self.certfile = certfile
self.cert_reqs = cert_reqs
self.ssl_version = ssl_version
self.ca_certs = ca_certs
def read(self, len=1024):
"""Read up to LEN bytes and return them.
Return zero-length string on EOF."""
return self._sslobj.read(len)
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__)
return self._sslobj.write(data)
else:
return socket.send(self, data, flags)
def send_to (self, data, addr, flags=0):
if self._sslobj:
raise ValueError("send_to not allowed on instances of %s" %
self.__class__)
else:
return socket.send_to(self, data, addr, flags)
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__)
return self._sslobj.write(data)
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 sendall() on %s" %
self.__class__)
return self._sslobj.read(data, buflen)
else:
return socket.recv(self, buflen, flags)
def recv_from (self, addr, buflen=1024, flags=0):
if self._sslobj:
raise ValueError("recv_from not allowed on instances of %s" %
self.__class__)
else:
return socket.recv_from(self, addr, buflen, flags)
def shutdown(self, how):
self._sslobj = None
socket.shutdown(self, how)
def close(self):
self._sslobj = None
socket.close(self)
def connect(self, addr):
"""Connects to remote ADDR, and then wraps the connection in
an SSL channel."""
# 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._sslobj:
raise ValueError("attempt to connect already-connected SSLSocket!")
socket.connect(self, addr)
self._sslobj = _ssl.sslwrap(self._sock, False, self.keyfile, self.certfile,
self.cert_reqs, self.ssl_version,
self.ca_certs)
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, True, self.keyfile, self.certfile,
self.cert_reqs, self.ssl_version,
self.ca_certs), addr)
def makefile(self, mode='r', bufsize=-1):
"""Ouch. Need to make and return a file-like object that
works with the SSL connection."""
if self._sslobj:
return SSLFileStream(self._sslobj, mode, bufsize)
else:
return socket.makefile(self, mode, bufsize)
class SSLFileStream:
"""A class to simulate a file stream on top of a socket.
Most of this is just lifted from the socket module, and
adjusted to work with an SSL stream instead of a socket."""
default_bufsize = 8192
name = "<SSL stream>"
__slots__ = ["mode", "bufsize", "softspace",
# "closed" is a property, see below
"_sslobj", "_rbufsize", "_wbufsize", "_rbuf", "_wbuf",
"_close", "_fileno"]
def __init__(self, sslobj, mode='rb', bufsize=-1, close=False):
self._sslobj = sslobj
self.mode = mode # Not actually used in this version
if bufsize < 0:
bufsize = self.default_bufsize
self.bufsize = bufsize
self.softspace = False
if bufsize == 0:
self._rbufsize = 1
elif bufsize == 1:
self._rbufsize = self.default_bufsize
else:
self._rbufsize = bufsize
self._wbufsize = bufsize
self._rbuf = "" # A string
self._wbuf = [] # A list of strings
self._close = close
self._fileno = -1
def _getclosed(self):
return self._sslobj is None
closed = property(_getclosed, doc="True if the file is closed")
def fileno(self):
return self._fileno
def close(self):
try:
if self._sslobj:
self.flush()
finally:
if self._close and self._sslobj:
self._sslobj.close()
self._sslobj = None
def __del__(self):
try:
self.close()
except:
# close() may fail if __init__ didn't complete
pass
def flush(self):
if self._wbuf:
buffer = "".join(self._wbuf)
self._wbuf = []
count = 0
while (count < len(buffer)):
written = self._sslobj.write(buffer)
count += written
buffer = buffer[written:]
def write(self, data):
data = str(data) # XXX Should really reject non-string non-buffers
if not data:
return
self._wbuf.append(data)
if (self._wbufsize == 0 or
self._wbufsize == 1 and '\n' in data or
self._get_wbuf_len() >= self._wbufsize):
self.flush()
def writelines(self, list):
# XXX We could do better here for very long lists
# XXX Should really reject non-string non-buffers
self._wbuf.extend(filter(None, map(str, list)))
if (self._wbufsize <= 1 or
self._get_wbuf_len() >= self._wbufsize):
self.flush()
def _get_wbuf_len(self):
buf_len = 0
for x in self._wbuf:
buf_len += len(x)
return buf_len
def read(self, size=-1):
data = self._rbuf
if size < 0:
# Read until EOF
buffers = []
if data:
buffers.append(data)
self._rbuf = ""
if self._rbufsize <= 1:
recv_size = self.default_bufsize
else:
recv_size = self._rbufsize
while True:
data = self._sslobj.read(recv_size)
if not data:
break
buffers.append(data)
return "".join(buffers)
else:
# Read until size bytes or EOF seen, whichever comes first
buf_len = len(data)
if buf_len >= size:
self._rbuf = data[size:]
return data[:size]
buffers = []
if data:
buffers.append(data)
self._rbuf = ""
while True:
left = size - buf_len
recv_size = max(self._rbufsize, left)
data = self._sslobj.read(recv_size)
if not data:
break
buffers.append(data)
n = len(data)
if n >= left:
self._rbuf = data[left:]
buffers[-1] = data[:left]
break
buf_len += n
return "".join(buffers)
def readline(self, size=-1):
data = self._rbuf
if size < 0:
# Read until \n or EOF, whichever comes first
if self._rbufsize <= 1:
# Speed up unbuffered case
assert data == ""
buffers = []
while data != "\n":
data = self._sslobj.read(1)
if not data:
break
buffers.append(data)
return "".join(buffers)
nl = data.find('\n')
if nl >= 0:
nl += 1
self._rbuf = data[nl:]
return data[:nl]
buffers = []
if data:
buffers.append(data)
self._rbuf = ""
while True:
data = self._sslobj.read(self._rbufsize)
if not data:
break
buffers.append(data)
nl = data.find('\n')
if nl >= 0:
nl += 1
self._rbuf = data[nl:]
buffers[-1] = data[:nl]
break
return "".join(buffers)
else:
# Read until size bytes or \n or EOF seen, whichever comes first
nl = data.find('\n', 0, size)
if nl >= 0:
nl += 1
self._rbuf = data[nl:]
return data[:nl]
buf_len = len(data)
if buf_len >= size:
self._rbuf = data[size:]
return data[:size]
buffers = []
if data:
buffers.append(data)
self._rbuf = ""
while True:
data = self._sslobj.read(self._rbufsize)
if not data:
break
buffers.append(data)
left = size - buf_len
nl = data.find('\n', 0, left)
if nl >= 0:
nl += 1
self._rbuf = data[nl:]
buffers[-1] = data[:nl]
break
n = len(data)
if n >= left:
self._rbuf = data[left:]
buffers[-1] = data[:left]
break
buf_len += n
return "".join(buffers)
def readlines(self, sizehint=0):
total = 0
list = []
while True:
line = self.readline()
if not line:
break
list.append(line)
total += len(line)
if sizehint and total >= sizehint:
break
return list
# Iterator protocols
def __iter__(self):
return self
def next(self):
line = self.readline()
if not line:
raise StopIteration
return line
def wrap_socket(sock, keyfile=None, certfile=None,
server_side=False, cert_reqs=CERT_NONE,
ssl_version=PROTOCOL_SSLv23, ca_certs=None):
return SSLSocket(sock, keyfile=keyfile, certfile=certfile,
server_side=server_side, cert_reqs=cert_reqs,
ssl_version=ssl_version, ca_certs=ca_certs)
# 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) +
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):
if protocol_code == PROTOCOL_TLSv1:
return "TLSv1"
elif protocol_code == PROTOCOL_SSLv23:
return "SSLv23"
elif protocol_code == PROTOCOL_SSLv2:
return "SSLv2"
elif protocol_code == PROTOCOL_SSLv3:
return "SSLv3"
else:
return "<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."""
return _ssl.sslwrap(sock._sock, 0, keyfile, certfile, CERT_NONE,
PROTOCOL_SSLv23, None)