source: python/trunk/Lib/ssl.py@ 389

Last change on this file since 389 was 2, checked in by Yuri Dario, 15 years ago

Initial import for vendor code.
  • Property svn:eol-style set to native
File size: 15.0 KB
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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 SSLError
63from _ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED
64from _ssl import PROTOCOL_SSLv2, PROTOCOL_SSLv3, PROTOCOL_SSLv23, PROTOCOL_TLSv1
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
76
77from socket import socket, _fileobject
78from socket import getnameinfo as _getnameinfo
79import base64 # for DER-to-PEM translation
80
81class SSLSocket(socket):
82
83 """This class implements a subtype of socket.socket that wraps
84 the underlying OS socket in an SSL context when necessary, and
85 provides read and write methods over that channel."""
86
87 def __init__(self, sock, keyfile=None, certfile=None,
88 server_side=False, cert_reqs=CERT_NONE,
89 ssl_version=PROTOCOL_SSLv23, ca_certs=None,
90 do_handshake_on_connect=True,
91 suppress_ragged_eofs=True):
92 socket.__init__(self, _sock=sock._sock)
93 # the initializer for socket trashes the methods (tsk, tsk), so...
94 self.send = lambda data, flags=0: SSLSocket.send(self, data, flags)
95 self.sendto = lambda data, addr, flags=0: SSLSocket.sendto(self, data, addr, flags)
96 self.recv = lambda buflen=1024, flags=0: SSLSocket.recv(self, buflen, flags)
97 self.recvfrom = lambda addr, buflen=1024, flags=0: SSLSocket.recvfrom(self, addr, buflen, flags)
98 self.recv_into = lambda buffer, nbytes=None, flags=0: SSLSocket.recv_into(self, buffer, nbytes, flags)
99 self.recvfrom_into = lambda buffer, nbytes=None, flags=0: SSLSocket.recvfrom_into(self, buffer, nbytes, flags)
100
101 if certfile and not keyfile:
102 keyfile = certfile
103 # see if it's connected
104 try:
105 socket.getpeername(self)
106 except:
107 # no, no connection yet
108 self._sslobj = None
109 else:
110 # yes, create the SSL object
111 self._sslobj = _ssl.sslwrap(self._sock, server_side,
112 keyfile, certfile,
113 cert_reqs, ssl_version, ca_certs)
114 if do_handshake_on_connect:
115 timeout = self.gettimeout()
116 try:
117 self.settimeout(None)
118 self.do_handshake()
119 finally:
120 self.settimeout(timeout)
121 self.keyfile = keyfile
122 self.certfile = certfile
123 self.cert_reqs = cert_reqs
124 self.ssl_version = ssl_version
125 self.ca_certs = ca_certs
126 self.do_handshake_on_connect = do_handshake_on_connect
127 self.suppress_ragged_eofs = suppress_ragged_eofs
128 self._makefile_refs = 0
129
130 def read(self, len=1024):
131
132 """Read up to LEN bytes and return them.
133 Return zero-length string on EOF."""
134
135 try:
136 return self._sslobj.read(len)
137 except SSLError, x:
138 if x.args[0] == SSL_ERROR_EOF and self.suppress_ragged_eofs:
139 return ''
140 else:
141 raise
142
143 def write(self, data):
144
145 """Write DATA to the underlying SSL channel. Returns
146 number of bytes of DATA actually transmitted."""
147
148 return self._sslobj.write(data)
149
150 def getpeercert(self, binary_form=False):
151
152 """Returns a formatted version of the data in the
153 certificate provided by the other end of the SSL channel.
154 Return None if no certificate was provided, {} if a
155 certificate was provided, but not validated."""
156
157 return self._sslobj.peer_certificate(binary_form)
158
159 def cipher(self):
160
161 if not self._sslobj:
162 return None
163 else:
164 return self._sslobj.cipher()
165
166 def send(self, data, flags=0):
167 if self._sslobj:
168 if flags != 0:
169 raise ValueError(
170 "non-zero flags not allowed in calls to send() on %s" %
171 self.__class__)
172 while True:
173 try:
174 v = self._sslobj.write(data)
175 except SSLError, x:
176 if x.args[0] == SSL_ERROR_WANT_READ:
177 return 0
178 elif x.args[0] == SSL_ERROR_WANT_WRITE:
179 return 0
180 else:
181 raise
182 else:
183 return v
184 else:
185 return socket.send(self, data, flags)
186
187 def sendto(self, data, addr, flags=0):
188 if self._sslobj:
189 raise ValueError("sendto not allowed on instances of %s" %
190 self.__class__)
191 else:
192 return socket.sendto(self, data, addr, flags)
193
194 def sendall(self, data, flags=0):
195 if self._sslobj:
196 if flags != 0:
197 raise ValueError(
198 "non-zero flags not allowed in calls to sendall() on %s" %
199 self.__class__)
200 amount = len(data)
201 count = 0
202 while (count < amount):
203 v = self.send(data[count:])
204 count += v
205 return amount
206 else:
207 return socket.sendall(self, data, flags)
208
209 def recv(self, buflen=1024, flags=0):
210 if self._sslobj:
211 if flags != 0:
212 raise ValueError(
213 "non-zero flags not allowed in calls to sendall() on %s" %
214 self.__class__)
215 while True:
216 try:
217 return self.read(buflen)
218 except SSLError, x:
219 if x.args[0] == SSL_ERROR_WANT_READ:
220 continue
221 else:
222 raise x
223 else:
224 return socket.recv(self, buflen, flags)
225
226 def recv_into(self, buffer, nbytes=None, flags=0):
227 if buffer and (nbytes is None):
228 nbytes = len(buffer)
229 elif nbytes is None:
230 nbytes = 1024
231 if self._sslobj:
232 if flags != 0:
233 raise ValueError(
234 "non-zero flags not allowed in calls to recv_into() on %s" %
235 self.__class__)
236 while True:
237 try:
238 tmp_buffer = self.read(nbytes)
239 v = len(tmp_buffer)
240 buffer[:v] = tmp_buffer
241 return v
242 except SSLError as x:
243 if x.args[0] == SSL_ERROR_WANT_READ:
244 continue
245 else:
246 raise x
247 else:
248 return socket.recv_into(self, buffer, nbytes, flags)
249
250 def recvfrom(self, addr, buflen=1024, flags=0):
251 if self._sslobj:
252 raise ValueError("recvfrom not allowed on instances of %s" %
253 self.__class__)
254 else:
255 return socket.recvfrom(self, addr, buflen, flags)
256
257 def recvfrom_into(self, buffer, nbytes=None, flags=0):
258 if self._sslobj:
259 raise ValueError("recvfrom_into not allowed on instances of %s" %
260 self.__class__)
261 else:
262 return socket.recvfrom_into(self, buffer, nbytes, flags)
263
264 def pending(self):
265 if self._sslobj:
266 return self._sslobj.pending()
267 else:
268 return 0
269
270 def unwrap(self):
271 if self._sslobj:
272 s = self._sslobj.shutdown()
273 self._sslobj = None
274 return s
275 else:
276 raise ValueError("No SSL wrapper around " + str(self))
277
278 def shutdown(self, how):
279 self._sslobj = None
280 socket.shutdown(self, how)
281
282 def close(self):
283 if self._makefile_refs < 1:
284 self._sslobj = None
285 socket.close(self)
286 else:
287 self._makefile_refs -= 1
288
289 def do_handshake(self):
290
291 """Perform a TLS/SSL handshake."""
292
293 self._sslobj.do_handshake()
294
295 def connect(self, addr):
296
297 """Connects to remote ADDR, and then wraps the connection in
298 an SSL channel."""
299
300 # Here we assume that the socket is client-side, and not
301 # connected at the time of the call. We connect it, then wrap it.
302 if self._sslobj:
303 raise ValueError("attempt to connect already-connected SSLSocket!")
304 socket.connect(self, addr)
305 self._sslobj = _ssl.sslwrap(self._sock, False, self.keyfile, self.certfile,
306 self.cert_reqs, self.ssl_version,
307 self.ca_certs)
308 if self.do_handshake_on_connect:
309 self.do_handshake()
310
311 def accept(self):
312
313 """Accepts a new connection from a remote client, and returns
314 a tuple containing that new connection wrapped with a server-side
315 SSL channel, and the address of the remote client."""
316
317 newsock, addr = socket.accept(self)
318 return (SSLSocket(newsock,
319 keyfile=self.keyfile,
320 certfile=self.certfile,
321 server_side=True,
322 cert_reqs=self.cert_reqs,
323 ssl_version=self.ssl_version,
324 ca_certs=self.ca_certs,
325 do_handshake_on_connect=self.do_handshake_on_connect,
326 suppress_ragged_eofs=self.suppress_ragged_eofs),
327 addr)
328
329 def makefile(self, mode='r', bufsize=-1):
330
331 """Make and return a file-like object that
332 works with the SSL connection. Just use the code
333 from the socket module."""
334
335 self._makefile_refs += 1
336 return _fileobject(self, mode, bufsize)
337
338
339
340def wrap_socket(sock, keyfile=None, certfile=None,
341 server_side=False, cert_reqs=CERT_NONE,
342 ssl_version=PROTOCOL_SSLv23, ca_certs=None,
343 do_handshake_on_connect=True,
344 suppress_ragged_eofs=True):
345
346 return SSLSocket(sock, keyfile=keyfile, certfile=certfile,
347 server_side=server_side, cert_reqs=cert_reqs,
348 ssl_version=ssl_version, ca_certs=ca_certs,
349 do_handshake_on_connect=do_handshake_on_connect,
350 suppress_ragged_eofs=suppress_ragged_eofs)
351
352
353# some utility functions
354
355def cert_time_to_seconds(cert_time):
356
357 """Takes a date-time string in standard ASN1_print form
358 ("MON DAY 24HOUR:MINUTE:SEC YEAR TIMEZONE") and return
359 a Python time value in seconds past the epoch."""
360
361 import time
362 return time.mktime(time.strptime(cert_time, "%b %d %H:%M:%S %Y GMT"))
363
364PEM_HEADER = "-----BEGIN CERTIFICATE-----"
365PEM_FOOTER = "-----END CERTIFICATE-----"
366
367def DER_cert_to_PEM_cert(der_cert_bytes):
368
369 """Takes a certificate in binary DER format and returns the
370 PEM version of it as a string."""
371
372 if hasattr(base64, 'standard_b64encode'):
373 # preferred because older API gets line-length wrong
374 f = base64.standard_b64encode(der_cert_bytes)
375 return (PEM_HEADER + '\n' +
376 textwrap.fill(f, 64) +
377 PEM_FOOTER + '\n')
378 else:
379 return (PEM_HEADER + '\n' +
380 base64.encodestring(der_cert_bytes) +
381 PEM_FOOTER + '\n')
382
383def PEM_cert_to_DER_cert(pem_cert_string):
384
385 """Takes a certificate in ASCII PEM format and returns the
386 DER-encoded version of it as a byte sequence"""
387
388 if not pem_cert_string.startswith(PEM_HEADER):
389 raise ValueError("Invalid PEM encoding; must start with %s"
390 % PEM_HEADER)
391 if not pem_cert_string.strip().endswith(PEM_FOOTER):
392 raise ValueError("Invalid PEM encoding; must end with %s"
393 % PEM_FOOTER)
394 d = pem_cert_string.strip()[len(PEM_HEADER):-len(PEM_FOOTER)]
395 return base64.decodestring(d)
396
397def get_server_certificate(addr, ssl_version=PROTOCOL_SSLv3, ca_certs=None):
398
399 """Retrieve the certificate from the server at the specified address,
400 and return it as a PEM-encoded string.
401 If 'ca_certs' is specified, validate the server cert against it.
402 If 'ssl_version' is specified, use it in the connection attempt."""
403
404 host, port = addr
405 if (ca_certs is not None):
406 cert_reqs = CERT_REQUIRED
407 else:
408 cert_reqs = CERT_NONE
409 s = wrap_socket(socket(), ssl_version=ssl_version,
410 cert_reqs=cert_reqs, ca_certs=ca_certs)
411 s.connect(addr)
412 dercert = s.getpeercert(True)
413 s.close()
414 return DER_cert_to_PEM_cert(dercert)
415
416def get_protocol_name(protocol_code):
417 if protocol_code == PROTOCOL_TLSv1:
418 return "TLSv1"
419 elif protocol_code == PROTOCOL_SSLv23:
420 return "SSLv23"
421 elif protocol_code == PROTOCOL_SSLv2:
422 return "SSLv2"
423 elif protocol_code == PROTOCOL_SSLv3:
424 return "SSLv3"
425 else:
426 return "<unknown>"
427
428
429# a replacement for the old socket.ssl function
430
431def sslwrap_simple(sock, keyfile=None, certfile=None):
432
433 """A replacement for the old socket.ssl function. Designed
434 for compability with Python 2.5 and earlier. Will disappear in
435 Python 3.0."""
436
437 if hasattr(sock, "_sock"):
438 sock = sock._sock
439
440 ssl_sock = _ssl.sslwrap(sock, 0, keyfile, certfile, CERT_NONE,
441 PROTOCOL_SSLv23, None)
442 try:
443 sock.getpeername()
444 except:
445 # no, no connection yet
446 pass
447 else:
448 # yes, do the handshake
449 ssl_sock.do_handshake()
450
451 return ssl_sock
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