source: python/trunk/Lib/ssl.py@ 394

Last change on this file since 394 was 391, checked in by dmik, 11 years ago

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1# Wrapper module for _ssl, providing some additional facilities
2# implemented in Python. Written by Bill Janssen.
3
4"""\
5This module provides some more Pythonic support for SSL.
6
7Object types:
8
9 SSLSocket -- subtype of socket.socket which does SSL over the socket
10
11Exceptions:
12
13 SSLError -- exception raised for I/O errors
14
15Functions:
16
17 cert_time_to_seconds -- convert time string used for certificate
18 notBefore and notAfter functions to integer
19 seconds past the Epoch (the time values
20 returned from time.time())
21
22 fetch_server_certificate (HOST, PORT) -- fetch the certificate provided
23 by the server running on HOST at port PORT. No
24 validation of the certificate is performed.
25
26Integer constants:
27
28SSL_ERROR_ZERO_RETURN
29SSL_ERROR_WANT_READ
30SSL_ERROR_WANT_WRITE
31SSL_ERROR_WANT_X509_LOOKUP
32SSL_ERROR_SYSCALL
33SSL_ERROR_SSL
34SSL_ERROR_WANT_CONNECT
35
36SSL_ERROR_EOF
37SSL_ERROR_INVALID_ERROR_CODE
38
39The following group define certificate requirements that one side is
40allowing/requiring from the other side:
41
42CERT_NONE - no certificates from the other side are required (or will
43 be looked at if provided)
44CERT_OPTIONAL - certificates are not required, but if provided will be
45 validated, and if validation fails, the connection will
46 also fail
47CERT_REQUIRED - certificates are required, and will be validated, and
48 if validation fails, the connection will also fail
49
50The following constants identify various SSL protocol variants:
51
52PROTOCOL_SSLv2
53PROTOCOL_SSLv3
54PROTOCOL_SSLv23
55PROTOCOL_TLSv1
56"""
57
58import textwrap
59
60import _ssl # if we can't import it, let the error propagate
61
62from _ssl import OPENSSL_VERSION_NUMBER, OPENSSL_VERSION_INFO, OPENSSL_VERSION
63from _ssl import SSLError
64from _ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED
65from _ssl import RAND_status, RAND_egd, RAND_add
66from _ssl import \
67 SSL_ERROR_ZERO_RETURN, \
68 SSL_ERROR_WANT_READ, \
69 SSL_ERROR_WANT_WRITE, \
70 SSL_ERROR_WANT_X509_LOOKUP, \
71 SSL_ERROR_SYSCALL, \
72 SSL_ERROR_SSL, \
73 SSL_ERROR_WANT_CONNECT, \
74 SSL_ERROR_EOF, \
75 SSL_ERROR_INVALID_ERROR_CODE
76from _ssl import PROTOCOL_SSLv3, PROTOCOL_SSLv23, PROTOCOL_TLSv1
77_PROTOCOL_NAMES = {
78 PROTOCOL_TLSv1: "TLSv1",
79 PROTOCOL_SSLv23: "SSLv23",
80 PROTOCOL_SSLv3: "SSLv3",
81}
82try:
83 from _ssl import PROTOCOL_SSLv2
84 _SSLv2_IF_EXISTS = PROTOCOL_SSLv2
85except ImportError:
86 _SSLv2_IF_EXISTS = None
87else:
88 _PROTOCOL_NAMES[PROTOCOL_SSLv2] = "SSLv2"
89
90from socket import socket, _fileobject, _delegate_methods, error as socket_error
91from socket import getnameinfo as _getnameinfo
92import base64 # for DER-to-PEM translation
93import errno
94
95# Disable weak or insecure ciphers by default
96# (OpenSSL's default setting is 'DEFAULT:!aNULL:!eNULL')
97_DEFAULT_CIPHERS = 'DEFAULT:!aNULL:!eNULL:!LOW:!EXPORT:!SSLv2'
98
99
100class SSLSocket(socket):
101
102 """This class implements a subtype of socket.socket that wraps
103 the underlying OS socket in an SSL context when necessary, and
104 provides read and write methods over that channel."""
105
106 def __init__(self, sock, keyfile=None, certfile=None,
107 server_side=False, cert_reqs=CERT_NONE,
108 ssl_version=PROTOCOL_SSLv23, ca_certs=None,
109 do_handshake_on_connect=True,
110 suppress_ragged_eofs=True, ciphers=None):
111 socket.__init__(self, _sock=sock._sock)
112 # The initializer for socket overrides the methods send(), recv(), etc.
113 # in the instancce, which we don't need -- but we want to provide the
114 # methods defined in SSLSocket.
115 for attr in _delegate_methods:
116 try:
117 delattr(self, attr)
118 except AttributeError:
119 pass
120
121 if ciphers is None and ssl_version != _SSLv2_IF_EXISTS:
122 ciphers = _DEFAULT_CIPHERS
123
124 if certfile and not keyfile:
125 keyfile = certfile
126 # see if it's connected
127 try:
128 socket.getpeername(self)
129 except socket_error, e:
130 if e.errno != errno.ENOTCONN:
131 raise
132 # no, no connection yet
133 self._connected = False
134 self._sslobj = None
135 else:
136 # yes, create the SSL object
137 self._connected = True
138 self._sslobj = _ssl.sslwrap(self._sock, server_side,
139 keyfile, certfile,
140 cert_reqs, ssl_version, ca_certs,
141 ciphers)
142 if do_handshake_on_connect:
143 self.do_handshake()
144 self.keyfile = keyfile
145 self.certfile = certfile
146 self.cert_reqs = cert_reqs
147 self.ssl_version = ssl_version
148 self.ca_certs = ca_certs
149 self.ciphers = ciphers
150 self.do_handshake_on_connect = do_handshake_on_connect
151 self.suppress_ragged_eofs = suppress_ragged_eofs
152 self._makefile_refs = 0
153
154 def read(self, len=1024):
155
156 """Read up to LEN bytes and return them.
157 Return zero-length string on EOF."""
158
159 try:
160 return self._sslobj.read(len)
161 except SSLError, x:
162 if x.args[0] == SSL_ERROR_EOF and self.suppress_ragged_eofs:
163 return ''
164 else:
165 raise
166
167 def write(self, data):
168
169 """Write DATA to the underlying SSL channel. Returns
170 number of bytes of DATA actually transmitted."""
171
172 return self._sslobj.write(data)
173
174 def getpeercert(self, binary_form=False):
175
176 """Returns a formatted version of the data in the
177 certificate provided by the other end of the SSL channel.
178 Return None if no certificate was provided, {} if a
179 certificate was provided, but not validated."""
180
181 return self._sslobj.peer_certificate(binary_form)
182
183 def cipher(self):
184
185 if not self._sslobj:
186 return None
187 else:
188 return self._sslobj.cipher()
189
190 def send(self, data, flags=0):
191 if self._sslobj:
192 if flags != 0:
193 raise ValueError(
194 "non-zero flags not allowed in calls to send() on %s" %
195 self.__class__)
196 while True:
197 try:
198 v = self._sslobj.write(data)
199 except SSLError, x:
200 if x.args[0] == SSL_ERROR_WANT_READ:
201 return 0
202 elif x.args[0] == SSL_ERROR_WANT_WRITE:
203 return 0
204 else:
205 raise
206 else:
207 return v
208 else:
209 return self._sock.send(data, flags)
210
211 def sendto(self, data, flags_or_addr, addr=None):
212 if self._sslobj:
213 raise ValueError("sendto not allowed on instances of %s" %
214 self.__class__)
215 elif addr is None:
216 return self._sock.sendto(data, flags_or_addr)
217 else:
218 return self._sock.sendto(data, flags_or_addr, addr)
219
220 def sendall(self, data, flags=0):
221 if self._sslobj:
222 if flags != 0:
223 raise ValueError(
224 "non-zero flags not allowed in calls to sendall() on %s" %
225 self.__class__)
226 amount = len(data)
227 count = 0
228 while (count < amount):
229 v = self.send(data[count:])
230 count += v
231 return amount
232 else:
233 return socket.sendall(self, data, flags)
234
235 def recv(self, buflen=1024, flags=0):
236 if self._sslobj:
237 if flags != 0:
238 raise ValueError(
239 "non-zero flags not allowed in calls to recv() on %s" %
240 self.__class__)
241 return self.read(buflen)
242 else:
243 return self._sock.recv(buflen, flags)
244
245 def recv_into(self, buffer, nbytes=None, flags=0):
246 if buffer and (nbytes is None):
247 nbytes = len(buffer)
248 elif nbytes is None:
249 nbytes = 1024
250 if self._sslobj:
251 if flags != 0:
252 raise ValueError(
253 "non-zero flags not allowed in calls to recv_into() on %s" %
254 self.__class__)
255 tmp_buffer = self.read(nbytes)
256 v = len(tmp_buffer)
257 buffer[:v] = tmp_buffer
258 return v
259 else:
260 return self._sock.recv_into(buffer, nbytes, flags)
261
262 def recvfrom(self, buflen=1024, flags=0):
263 if self._sslobj:
264 raise ValueError("recvfrom not allowed on instances of %s" %
265 self.__class__)
266 else:
267 return self._sock.recvfrom(buflen, flags)
268
269 def recvfrom_into(self, buffer, nbytes=None, flags=0):
270 if self._sslobj:
271 raise ValueError("recvfrom_into not allowed on instances of %s" %
272 self.__class__)
273 else:
274 return self._sock.recvfrom_into(buffer, nbytes, flags)
275
276 def pending(self):
277 if self._sslobj:
278 return self._sslobj.pending()
279 else:
280 return 0
281
282 def unwrap(self):
283 if self._sslobj:
284 s = self._sslobj.shutdown()
285 self._sslobj = None
286 return s
287 else:
288 raise ValueError("No SSL wrapper around " + str(self))
289
290 def shutdown(self, how):
291 self._sslobj = None
292 socket.shutdown(self, how)
293
294 def close(self):
295 if self._makefile_refs < 1:
296 self._sslobj = None
297 socket.close(self)
298 else:
299 self._makefile_refs -= 1
300
301 def do_handshake(self):
302
303 """Perform a TLS/SSL handshake."""
304
305 self._sslobj.do_handshake()
306
307 def _real_connect(self, addr, return_errno):
308 # Here we assume that the socket is client-side, and not
309 # connected at the time of the call. We connect it, then wrap it.
310 if self._connected:
311 raise ValueError("attempt to connect already-connected SSLSocket!")
312 self._sslobj = _ssl.sslwrap(self._sock, False, self.keyfile, self.certfile,
313 self.cert_reqs, self.ssl_version,
314 self.ca_certs, self.ciphers)
315 try:
316 if return_errno:
317 rc = socket.connect_ex(self, addr)
318 else:
319 rc = None
320 socket.connect(self, addr)
321 if not rc:
322 if self.do_handshake_on_connect:
323 self.do_handshake()
324 self._connected = True
325 return rc
326 except socket_error:
327 self._sslobj = None
328 raise
329
330 def connect(self, addr):
331 """Connects to remote ADDR, and then wraps the connection in
332 an SSL channel."""
333 self._real_connect(addr, False)
334
335 def connect_ex(self, addr):
336 """Connects to remote ADDR, and then wraps the connection in
337 an SSL channel."""
338 return self._real_connect(addr, True)
339
340 def accept(self):
341
342 """Accepts a new connection from a remote client, and returns
343 a tuple containing that new connection wrapped with a server-side
344 SSL channel, and the address of the remote client."""
345
346 newsock, addr = socket.accept(self)
347 try:
348 return (SSLSocket(newsock,
349 keyfile=self.keyfile,
350 certfile=self.certfile,
351 server_side=True,
352 cert_reqs=self.cert_reqs,
353 ssl_version=self.ssl_version,
354 ca_certs=self.ca_certs,
355 ciphers=self.ciphers,
356 do_handshake_on_connect=self.do_handshake_on_connect,
357 suppress_ragged_eofs=self.suppress_ragged_eofs),
358 addr)
359 except socket_error as e:
360 newsock.close()
361 raise e
362
363 def makefile(self, mode='r', bufsize=-1):
364
365 """Make and return a file-like object that
366 works with the SSL connection. Just use the code
367 from the socket module."""
368
369 self._makefile_refs += 1
370 # close=True so as to decrement the reference count when done with
371 # the file-like object.
372 return _fileobject(self, mode, bufsize, close=True)
373
374
375
376def wrap_socket(sock, keyfile=None, certfile=None,
377 server_side=False, cert_reqs=CERT_NONE,
378 ssl_version=PROTOCOL_SSLv23, ca_certs=None,
379 do_handshake_on_connect=True,
380 suppress_ragged_eofs=True, ciphers=None):
381
382 return SSLSocket(sock, keyfile=keyfile, certfile=certfile,
383 server_side=server_side, cert_reqs=cert_reqs,
384 ssl_version=ssl_version, ca_certs=ca_certs,
385 do_handshake_on_connect=do_handshake_on_connect,
386 suppress_ragged_eofs=suppress_ragged_eofs,
387 ciphers=ciphers)
388
389
390# some utility functions
391
392def cert_time_to_seconds(cert_time):
393
394 """Takes a date-time string in standard ASN1_print form
395 ("MON DAY 24HOUR:MINUTE:SEC YEAR TIMEZONE") and return
396 a Python time value in seconds past the epoch."""
397
398 import time
399 return time.mktime(time.strptime(cert_time, "%b %d %H:%M:%S %Y GMT"))
400
401PEM_HEADER = "-----BEGIN CERTIFICATE-----"
402PEM_FOOTER = "-----END CERTIFICATE-----"
403
404def DER_cert_to_PEM_cert(der_cert_bytes):
405
406 """Takes a certificate in binary DER format and returns the
407 PEM version of it as a string."""
408
409 if hasattr(base64, 'standard_b64encode'):
410 # preferred because older API gets line-length wrong
411 f = base64.standard_b64encode(der_cert_bytes)
412 return (PEM_HEADER + '\n' +
413 textwrap.fill(f, 64) + '\n' +
414 PEM_FOOTER + '\n')
415 else:
416 return (PEM_HEADER + '\n' +
417 base64.encodestring(der_cert_bytes) +
418 PEM_FOOTER + '\n')
419
420def PEM_cert_to_DER_cert(pem_cert_string):
421
422 """Takes a certificate in ASCII PEM format and returns the
423 DER-encoded version of it as a byte sequence"""
424
425 if not pem_cert_string.startswith(PEM_HEADER):
426 raise ValueError("Invalid PEM encoding; must start with %s"
427 % PEM_HEADER)
428 if not pem_cert_string.strip().endswith(PEM_FOOTER):
429 raise ValueError("Invalid PEM encoding; must end with %s"
430 % PEM_FOOTER)
431 d = pem_cert_string.strip()[len(PEM_HEADER):-len(PEM_FOOTER)]
432 return base64.decodestring(d)
433
434def get_server_certificate(addr, ssl_version=PROTOCOL_SSLv3, ca_certs=None):
435
436 """Retrieve the certificate from the server at the specified address,
437 and return it as a PEM-encoded string.
438 If 'ca_certs' is specified, validate the server cert against it.
439 If 'ssl_version' is specified, use it in the connection attempt."""
440
441 host, port = addr
442 if (ca_certs is not None):
443 cert_reqs = CERT_REQUIRED
444 else:
445 cert_reqs = CERT_NONE
446 s = wrap_socket(socket(), ssl_version=ssl_version,
447 cert_reqs=cert_reqs, ca_certs=ca_certs)
448 s.connect(addr)
449 dercert = s.getpeercert(True)
450 s.close()
451 return DER_cert_to_PEM_cert(dercert)
452
453def get_protocol_name(protocol_code):
454 return _PROTOCOL_NAMES.get(protocol_code, '<unknown>')
455
456
457# a replacement for the old socket.ssl function
458
459def sslwrap_simple(sock, keyfile=None, certfile=None):
460
461 """A replacement for the old socket.ssl function. Designed
462 for compability with Python 2.5 and earlier. Will disappear in
463 Python 3.0."""
464
465 if hasattr(sock, "_sock"):
466 sock = sock._sock
467
468 ssl_sock = _ssl.sslwrap(sock, 0, keyfile, certfile, CERT_NONE,
469 PROTOCOL_SSLv23, None)
470 try:
471 sock.getpeername()
472 except socket_error:
473 # no, no connection yet
474 pass
475 else:
476 # yes, do the handshake
477 ssl_sock.do_handshake()
478
479 return ssl_sock
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