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Issue #14204: The ssl module now has support for the Next Protocol Negotiation extension, if available in the underlying OpenSSL library.

Browse source 
Patch by Colin Marc.
This commit is contained in:
Antoine Pitrou 2012-03-22 00:23:03 +01:00
parent a966c6fddb
commit d5d17eb653
6 changed files with 228 additions and 8 deletions
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35
Doc/library/ssl.rst
View file

@ -470,6 +470,16 @@ Constants
.. versionadded:: 3.2
.. data:: HAS_NPN
Whether the OpenSSL library has built-in support for *Next Protocol
Negotiation* as described in the `NPN draft specification
<http://tools.ietf.org/html/draft-agl-tls-nextprotoneg>`_. When true,
you can use the :meth:`SSLContext.set_npn_protocols` method to advertise
which protocols you want to support.
.. versionadded:: 3.3
.. data:: CHANNEL_BINDING_TYPES
List of supported TLS channel binding types. Strings in this list
@ -609,6 +619,15 @@ SSL sockets also have the following additional methods and attributes:
.. versionadded:: 3.3
.. method:: SSLSocket.selected_npn_protocol()
Returns the protocol that was selected during the TLS/SSL handshake. If
:meth:`SSLContext.set_npn_protocols` was not called, or if the other party
does not support NPN, or if the handshake has not yet happened, this will
return ``None``.
.. versionadded:: 3.3
.. method:: SSLSocket.unwrap()
Performs the SSL shutdown handshake, which removes the TLS layer from the
@ -617,7 +636,6 @@ SSL sockets also have the following additional methods and attributes:
returned socket should always be used for further communication with the
other side of the connection, rather than the original socket.
.. attribute:: SSLSocket.context
The :class:`SSLContext` object this SSL socket is tied to. If the SSL
@ -715,6 +733,21 @@ to speed up repeated connections from the same clients.
when connected, the :meth:`SSLSocket.cipher` method of SSL sockets will
give the currently selected cipher.
.. method:: SSLContext.set_npn_protocols(protocols)
Specify which protocols the socket should avertise during the SSL/TLS
handshake. It should be a list of strings, like ``['http/1.1', 'spdy/2']``,
ordered by preference. The selection of a protocol will happen during the
handshake, and will play out according to the `NPN draft specification
<http://tools.ietf.org/html/draft-agl-tls-nextprotoneg>`_. After a
successful handshake, the :meth:`SSLSocket.selected_npn_protocol` method will
return the agreed-upon protocol.
This method will raise :exc:`NotImplementedError` if :data:`HAS_NPN` is
False.
.. versionadded:: 3.3
.. method:: SSLContext.load_dh_params(dhfile)
Load the key generation parameters for Diffie-Helman (DH) key exchange.

27
Lib/ssl.py
View file

@ -90,7 +90,7 @@
SSL_ERROR_EOF,
SSL_ERROR_INVALID_ERROR_CODE,
)
from _ssl import HAS_SNI, HAS_ECDH
from _ssl import HAS_SNI, HAS_ECDH, HAS_NPN
from _ssl import (PROTOCOL_SSLv3, PROTOCOL_SSLv23,
PROTOCOL_TLSv1)
from _ssl import _OPENSSL_API_VERSION
@ -209,6 +209,17 @@ def wrap_socket(self, sock, server_side=False,
server_hostname=server_hostname,
_context=self)
def set_npn_protocols(self, npn_protocols):
protos = bytearray()
for protocol in npn_protocols:
b = bytes(protocol, 'ascii')
if len(b) == 0 or len(b) > 255:
raise SSLError('NPN protocols must be 1 to 255 in length')
protos.append(len(b))
protos.extend(b)
self._set_npn_protocols(protos)
class SSLSocket(socket):
"""This class implements a subtype of socket.socket that wraps
@ -220,7 +231,7 @@ def __init__(self, sock=None, keyfile=None, certfile=None,
ssl_version=PROTOCOL_SSLv23, ca_certs=None,
do_handshake_on_connect=True,
family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None,
suppress_ragged_eofs=True, ciphers=None,
suppress_ragged_eofs=True, npn_protocols=None, ciphers=None,
server_hostname=None,
_context=None):
@ -240,6 +251,8 @@ def __init__(self, sock=None, keyfile=None, certfile=None,
self.context.load_verify_locations(ca_certs)
if certfile:
self.context.load_cert_chain(certfile, keyfile)
if npn_protocols:
self.context.set_npn_protocols(npn_protocols)
if ciphers:
self.context.set_ciphers(ciphers)
self.keyfile = keyfile
@ -340,6 +353,13 @@ def getpeercert(self, binary_form=False):
self._checkClosed()
return self._sslobj.peer_certificate(binary_form)
def selected_npn_protocol(self):
self._checkClosed()
if not self._sslobj or not _ssl.HAS_NPN:
return None
else:
return self._sslobj.selected_npn_protocol()
def cipher(self):
self._checkClosed()
if not self._sslobj:
@ -568,7 +588,8 @@ 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):
suppress_ragged_eofs=True,
ciphers=None):
return SSLSocket(sock=sock, keyfile=keyfile, certfile=certfile,
server_side=server_side, cert_reqs=cert_reqs,

54
Lib/test/test_ssl.py
View file

@ -879,6 +879,7 @@ def wrap_conn(self):
try:
self.sslconn = self.server.context.wrap_socket(
self.sock, server_side=True)
self.server.selected_protocols.append(self.sslconn.selected_npn_protocol())
except ssl.SSLError as e:
# XXX Various errors can have happened here, for example
# a mismatching protocol version, an invalid certificate,
@ -901,6 +902,8 @@ def wrap_conn(self):
cipher = self.sslconn.cipher()
if support.verbose and self.server.chatty:
sys.stdout.write(" server: connection cipher is now " + str(cipher) + "\n")
sys.stdout.write(" server: selected protocol is now "
+ str(self.sslconn.selected_npn_protocol()) + "\n")
return True
def read(self):
@ -979,7 +982,7 @@ def run(self):
def __init__(self, certificate=None, ssl_version=None,
certreqs=None, cacerts=None,
chatty=True, connectionchatty=False, starttls_server=False,
ciphers=None, context=None):
npn_protocols=None, ciphers=None, context=None):
if context:
self.context = context
else:
@ -992,6 +995,8 @@ def __init__(self, certificate=None, ssl_version=None,
self.context.load_verify_locations(cacerts)
if certificate:
self.context.load_cert_chain(certificate)
if npn_protocols:
self.context.set_npn_protocols(npn_protocols)
if ciphers:
self.context.set_ciphers(ciphers)
self.chatty = chatty
@ -1001,6 +1006,7 @@ def __init__(self, certificate=None, ssl_version=None,
self.port = support.bind_port(self.sock)
self.flag = None
self.active = False
self.selected_protocols = []
self.conn_errors = []
threading.Thread.__init__(self)
self.daemon = True
@ -1195,6 +1201,7 @@ def server_params_test(client_context, server_context, indata=b"FOO\n",
Launch a server, connect a client to it and try various reads
and writes.
"""
stats = {}
server = ThreadedEchoServer(context=server_context,
chatty=chatty,
connectionchatty=False)
@ -1220,12 +1227,14 @@ def server_params_test(client_context, server_context, indata=b"FOO\n",
if connectionchatty:
if support.verbose:
sys.stdout.write(" client: closing connection.\n")
stats = {
stats.update({
'compression': s.compression(),
'cipher': s.cipher(),
}
'client_npn_protocol': s.selected_npn_protocol()
})
s.close()
return stats
stats['server_npn_protocols'] = server.selected_protocols
return stats
def try_protocol_combo(server_protocol, client_protocol, expect_success,
certsreqs=None, server_options=0, client_options=0):
@ -1853,6 +1862,43 @@ def test_dh_params(self):
if "ADH" not in parts and "EDH" not in parts and "DHE" not in parts:
self.fail("Non-DH cipher: " + cipher[0])
def test_selected_npn_protocol(self):
# selected_npn_protocol() is None unless NPN is used
context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
context.load_cert_chain(CERTFILE)
stats = server_params_test(context, context,
chatty=True, connectionchatty=True)
self.assertIs(stats['client_npn_protocol'], None)
@unittest.skipUnless(ssl.HAS_NPN, "NPN support needed for this test")
def test_npn_protocols(self):
server_protocols = ['http/1.1', 'spdy/2']
protocol_tests = [
(['http/1.1', 'spdy/2'], 'http/1.1'),
(['spdy/2', 'http/1.1'], 'http/1.1'),
(['spdy/2', 'test'], 'spdy/2'),
(['abc', 'def'], 'abc')
]
for client_protocols, expected in protocol_tests:
server_context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
server_context.load_cert_chain(CERTFILE)
server_context.set_npn_protocols(server_protocols)
client_context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
client_context.load_cert_chain(CERTFILE)
client_context.set_npn_protocols(client_protocols)
stats = server_params_test(client_context, server_context,
chatty=True, connectionchatty=True)
msg = "failed trying %s (s) and %s (c).\n" \
"was expecting %s, but got %%s from the %%s" \
% (str(server_protocols), str(client_protocols),
str(expected))
client_result = stats['client_npn_protocol']
self.assertEqual(client_result, expected, msg % (client_result, "client"))
server_result = stats['server_npn_protocols'][-1] \
if len(stats['server_npn_protocols']) else 'nothing'
self.assertEqual(server_result, expected, msg % (server_result, "server"))
def test_main(verbose=False):
if support.verbose:

1
Misc/ACKS
View file

@ -644,6 +644,7 @@ Grzegorz Makarewicz
David Malcolm
Ken Manheimer
Vladimir Marangozov
Colin Marc
David Marek
Doug Marien
Sven Marnach

4
Misc/NEWS
View file

@ -30,6 +30,10 @@ Core and Builtins
Library
-------
- Issue #14204: The ssl module now has support for the Next Protocol
Negotiation extension, if available in the underlying OpenSSL library.
Patch by Colin Marc.
- Issue #3035: Unused functions from tkinter are marked as pending peprecated.
- Issue #12757: Fix the skipping of doctests when python is run with -OO so

115
Modules/_ssl.c
View file

@ -159,6 +159,10 @@ static unsigned int _ssl_locks_count = 0;
typedef struct {
PyObject_HEAD
SSL_CTX *ctx;
#ifdef OPENSSL_NPN_NEGOTIATED
char *npn_protocols;
int npn_protocols_len;
#endif
} PySSLContext;
typedef struct {
@ -1015,6 +1019,20 @@ static PyObject *PySSL_cipher (PySSLSocket *self) {
return NULL;
}
#ifdef OPENSSL_NPN_NEGOTIATED
static PyObject *PySSL_selected_npn_protocol(PySSLSocket *self) {
const unsigned char *out;
unsigned int outlen;
SSL_get0_next_proto_negotiated(self->ssl,
&out, &outlen);
if (out == NULL)
Py_RETURN_NONE;
return PyUnicode_FromStringAndSize((char *) out, outlen);
}
#endif
static PyObject *PySSL_compression(PySSLSocket *self) {
#ifdef OPENSSL_NO_COMP
Py_RETURN_NONE;
@ -1487,6 +1505,9 @@ static PyMethodDef PySSLMethods[] = {
{"peer_certificate", (PyCFunction)PySSL_peercert, METH_VARARGS,
PySSL_peercert_doc},
{"cipher", (PyCFunction)PySSL_cipher, METH_NOARGS},
#ifdef OPENSSL_NPN_NEGOTIATED
{"selected_npn_protocol", (PyCFunction)PySSL_selected_npn_protocol, METH_NOARGS},
#endif
{"compression", (PyCFunction)PySSL_compression, METH_NOARGS},
{"shutdown", (PyCFunction)PySSL_SSLshutdown, METH_NOARGS,
PySSL_SSLshutdown_doc},
@ -1597,6 +1618,9 @@ static void
context_dealloc(PySSLContext *self)
{
SSL_CTX_free(self->ctx);
#ifdef OPENSSL_NPN_NEGOTIATED
PyMem_Free(self->npn_protocols);
#endif
Py_TYPE(self)->tp_free(self);
}
@ -1621,6 +1645,87 @@ set_ciphers(PySSLContext *self, PyObject *args)
Py_RETURN_NONE;
}
#ifdef OPENSSL_NPN_NEGOTIATED
/* this callback gets passed to SSL_CTX_set_next_protos_advertise_cb */
static int
_advertiseNPN_cb(SSL *s,
const unsigned char **data, unsigned int *len,
void *args)
{
PySSLContext *ssl_ctx = (PySSLContext *) args;
if (ssl_ctx->npn_protocols == NULL) {
*data = (unsigned char *) "";
*len = 0;
} else {
*data = (unsigned char *) ssl_ctx->npn_protocols;
*len = ssl_ctx->npn_protocols_len;
}
return SSL_TLSEXT_ERR_OK;
}
/* this callback gets passed to SSL_CTX_set_next_proto_select_cb */
static int
_selectNPN_cb(SSL *s,
unsigned char **out, unsigned char *outlen,
const unsigned char *server, unsigned int server_len,
void *args)
{
PySSLContext *ssl_ctx = (PySSLContext *) args;
unsigned char *client = (unsigned char *) ssl_ctx->npn_protocols;
int client_len;
if (client == NULL) {
client = (unsigned char *) "";
client_len = 0;
} else {
client_len = ssl_ctx->npn_protocols_len;
}
SSL_select_next_proto(out, outlen,
server, server_len,
client, client_len);
return SSL_TLSEXT_ERR_OK;
}
#endif
static PyObject *
_set_npn_protocols(PySSLContext *self, PyObject *args)
{
#ifdef OPENSSL_NPN_NEGOTIATED
Py_buffer protos;
if (!PyArg_ParseTuple(args, "y*:set_npn_protocols", &protos))
return NULL;
self->npn_protocols = PyMem_Malloc(protos.len);
if (self->npn_protocols == NULL) {
PyBuffer_Release(&protos);
return PyErr_NoMemory();
}
memcpy(self->npn_protocols, protos.buf, protos.len);
self->npn_protocols_len = (int) protos.len;
/* set both server and client callbacks, because the context can
* be used to create both types of sockets */
SSL_CTX_set_next_protos_advertised_cb(self->ctx,
_advertiseNPN_cb,
self);
SSL_CTX_set_next_proto_select_cb(self->ctx,
_selectNPN_cb,
self);
PyBuffer_Release(&protos);
Py_RETURN_NONE;
#else
PyErr_SetString(PyExc_NotImplementedError,
"The NPN extension requires OpenSSL 1.0.1 or later.");
return NULL;
#endif
}
static PyObject *
get_verify_mode(PySSLContext *self, void *c)
{
@ -2097,6 +2202,8 @@ static struct PyMethodDef context_methods[] = {
METH_VARARGS | METH_KEYWORDS, NULL},
{"set_ciphers", (PyCFunction) set_ciphers,
METH_VARARGS, NULL},
{"_set_npn_protocols", (PyCFunction) _set_npn_protocols,
METH_VARARGS, NULL},
{"load_cert_chain", (PyCFunction) load_cert_chain,
METH_VARARGS | METH_KEYWORDS, NULL},
{"load_dh_params", (PyCFunction) load_dh_params,
@ -2590,6 +2697,14 @@ PyInit__ssl(void)
Py_INCREF(r);
PyModule_AddObject(m, "HAS_ECDH", r);
#ifdef OPENSSL_NPN_NEGOTIATED
r = Py_True;
#else
r = Py_False;
#endif
Py_INCREF(r);
PyModule_AddObject(m, "HAS_NPN", r);
/* OpenSSL version */
/* SSLeay() gives us the version of the library linked against,
which could be different from the headers version.