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bpo-28134: Auto-detect socket values from file descriptor (#1349) 

Fix socket(fileno=fd) by auto-detecting the socket's family, type,
and proto from the file descriptor. The auto-detection can be overruled
by passing in family, type, and proto explicitly.

Without the fix, all socket except for TCP/IP over IPv4 are basically broken:

>>> s = socket.create_connection(('www.python.org', 443))
>>> s
<socket.socket fd=3, family=AddressFamily.AF_INET6, type=SocketKind.SOCK_STREAM, proto=6, laddr=('2003:58:bc4a:3b00:56ee:75ff:fe47:ca7b', 59730, 0, 0), raddr=('2a04:4e42:1b::223', 443, 0, 0)>
>>> socket.socket(fileno=s.fileno())
<socket.socket fd=3, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('2003:58:bc4a:3b00::%2550471192', 59730, 0, 2550471192), raddr=('2a04:4e42:1b:0:700c:e70b:ff7f:0%2550471192', 443, 0, 2550471192)>

Signed-off-by: Christian Heimes <christian@python.org>
This commit is contained in:
Christian Heimes 2018-01-29 22:37:58 +01:00 committed by GitHub
parent 72a0d218dc
commit b6e43af669
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 133 additions and 9 deletions
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13
Doc/library/socket.rst
View File

@ -461,10 +461,15 @@ The following functions all create :ref:`socket objects <socket-objects>`.
:const:`SOCK_DGRAM`, :const:`SOCK_RAW` or perhaps one of the other ``SOCK_``
constants. The protocol number is usually zero and may be omitted or in the
case where the address family is :const:`AF_CAN` the protocol should be one
of :const:`CAN_RAW`, :const:`CAN_BCM` or :const:`CAN_ISOTP`. If *fileno* is specified, the other
arguments are ignored, causing the socket with the specified file descriptor
to return. Unlike :func:`socket.fromfd`, *fileno* will return the same
socket and not a duplicate. This may help close a detached socket using
of :const:`CAN_RAW`, :const:`CAN_BCM` or :const:`CAN_ISOTP`
If *fileno* is specified, the values for *family*, *type*, and *proto* are
auto-detected from the specified file descriptor. Auto-detection can be
overruled by calling the function with explicit *family*, *type*, or *proto*
arguments. This only affects how Python represents e.g. the return value
of :meth:`socket.getpeername` but not the actual OS resource. Unlike
:func:`socket.fromfd`, *fileno* will return the same socket and not a
duplicate. This may help close a detached socket using
:meth:`socket.close()`.
The newly created socket is :ref:`non-inheritable <fd_inheritance>`.

9
Lib/socket.py
View File

@ -136,11 +136,18 @@ class socket(_socket.socket):
__slots__ = ["__weakref__", "_io_refs", "_closed"]
def __init__(self, family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None):
def __init__(self, family=-1, type=-1, proto=-1, fileno=None):
# For user code address family and type values are IntEnum members, but
# for the underlying _socket.socket they're just integers. The
# constructor of _socket.socket converts the given argument to an
# integer automatically.
if fileno is None:
if family == -1:
family = AF_INET
if type == -1:
type = SOCK_STREAM
if proto == -1:
proto = 0
_socket.socket.__init__(self, family, type, proto, fileno)
self._io_refs = 0
self._closed = False

2
Lib/test/_test_multiprocessing.py
View File

@ -4204,7 +4204,7 @@ class TestCloseFds(unittest.TestCase):
def close(self, fd):
if WIN32:
socket.socket(fileno=fd).close()
socket.socket(socket.AF_INET, socket.SOCK_STREAM, fileno=fd).close()
else:
os.close(fd)

45
Lib/test/test_socket.py
View File

@ -20,6 +20,7 @@ import math
import pickle
import struct
import random
import shutil
import string
import _thread as thread
import threading
@ -1284,6 +1285,7 @@ class GeneralModuleTests(unittest.TestCase):
def testCloseException(self):
sock = socket.socket()
sock.bind((socket._LOCALHOST, 0))
socket.socket(fileno=sock.fileno()).close()
try:
sock.close()
@ -1636,9 +1638,11 @@ class GeneralModuleTests(unittest.TestCase):
) + 1
with socket.socket(
family=unknown_family, type=unknown_type, fileno=fd) as s:
family=unknown_family, type=unknown_type, proto=23,
fileno=fd) as s:
self.assertEqual(s.family, unknown_family)
self.assertEqual(s.type, unknown_type)
self.assertEqual(s.proto, 23)
@unittest.skipUnless(hasattr(os, 'sendfile'), 'test needs os.sendfile()')
def test__sendfile_use_sendfile(self):
@ -1658,6 +1662,45 @@ class GeneralModuleTests(unittest.TestCase):
with self.assertRaises(TypeError):
sock._sendfile_use_sendfile(File(None))
def _test_socket_fileno(self, s, family, stype):
self.assertEqual(s.family, family)
self.assertEqual(s.type, stype)
fd = s.fileno()
s2 = socket.socket(fileno=fd)
self.addCleanup(s2.close)
# detach old fd to avoid double close
s.detach()
self.assertEqual(s2.family, family)
self.assertEqual(s2.type, stype)
self.assertEqual(s2.fileno(), fd)
def test_socket_fileno(self):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.addCleanup(s.close)
s.bind((support.HOST, 0))
self._test_socket_fileno(s, socket.AF_INET, socket.SOCK_STREAM)
if hasattr(socket, "SOCK_DGRAM"):
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self.addCleanup(s.close)
s.bind((support.HOST, 0))
self._test_socket_fileno(s, socket.AF_INET, socket.SOCK_DGRAM)
if support.IPV6_ENABLED:
s = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
self.addCleanup(s.close)
s.bind((support.HOSTv6, 0, 0, 0))
self._test_socket_fileno(s, socket.AF_INET6, socket.SOCK_STREAM)
if hasattr(socket, "AF_UNIX"):
tmpdir = tempfile.mkdtemp()
self.addCleanup(shutil.rmtree, tmpdir)
s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
self.addCleanup(s.close)
s.bind(os.path.join(tmpdir, 'socket'))
self._test_socket_fileno(s, socket.AF_UNIX, socket.SOCK_STREAM)
@unittest.skipUnless(HAVE_SOCKET_CAN, 'SocketCan required for this test.')
class BasicCANTest(unittest.TestCase):

2
Misc/NEWS.d/next/Library/2017-12-24-20-01-09.bpo-28134.HJ8Beb.rst Normal file
View File

@ -0,0 +1,2 @@
Sockets now auto-detect family, type and protocol from file descriptor by
default.

71
Modules/socketmodule.c
View File

@ -102,7 +102,8 @@ Local naming conventions:
/* Socket object documentation */
PyDoc_STRVAR(sock_doc,
"socket(family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None) -> socket object\n\
"socket(family=AF_INET, type=SOCK_STREAM, proto=0) -> socket object\n\
socket(family=-1, type=-1, proto=-1, fileno=None) -> socket object\n\
\n\
Open a socket of the given type. The family argument specifies the\n\
address family; it defaults to AF_INET. The type argument specifies\n\
@ -111,6 +112,9 @@ or datagram (SOCK_DGRAM) socket. The protocol argument defaults to 0,\n\
specifying the default protocol. Keyword arguments are accepted.\n\
The socket is created as non-inheritable.\n\
\n\
When a fileno is passed in, family, type and proto are auto-detected,\n\
unless they are explicitly set.\n\
\n\
A socket object represents one endpoint of a network connection.\n\
\n\
Methods of socket objects (keyword arguments not allowed):\n\
@ -4792,7 +4796,7 @@ sock_initobj(PyObject *self, PyObject *args, PyObject *kwds)
PySocketSockObject *s = (PySocketSockObject *)self;
PyObject *fdobj = NULL;
SOCKET_T fd = INVALID_SOCKET;
int family = AF_INET, type = SOCK_STREAM, proto = 0;
int family = -1, type = -1, proto = -1;
static char *keywords[] = {"family", "type", "proto", "fileno", 0};
#ifndef MS_WINDOWS
#ifdef SOCK_CLOEXEC
@ -4842,9 +4846,72 @@ sock_initobj(PyObject *self, PyObject *args, PyObject *kwds)
"can't use invalid socket value");
return -1;
}
if (family == -1) {
sock_addr_t addrbuf;
socklen_t addrlen = sizeof(sock_addr_t);
memset(&addrbuf, 0, addrlen);
if (getsockname(fd, SAS2SA(&addrbuf), &addrlen) == 0) {
family = SAS2SA(&addrbuf)->sa_family;
} else {
#ifdef MS_WINDOWS
PyErr_SetFromWindowsErrWithFilename(0, "family");
#else
PyErr_SetFromErrnoWithFilename(PyExc_OSError, "family");
#endif
return -1;
}
}
#ifdef SO_TYPE
if (type == -1) {
int tmp;
socklen_t slen = sizeof(tmp);
if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &tmp, &slen) == 0) {
type = tmp;
} else {
#ifdef MS_WINDOWS
PyErr_SetFromWindowsErrWithFilename(0, "type");
#else
PyErr_SetFromErrnoWithFilename(PyExc_OSError, "type");
#endif
return -1;
}
}
#else
type = SOCK_STREAM;
#endif
#ifdef SO_PROTOCOL
if (proto == -1) {
int tmp;
socklen_t slen = sizeof(tmp);
if (getsockopt(fd, SOL_SOCKET, SO_PROTOCOL, &tmp, &slen) == 0) {
proto = tmp;
} else {
#ifdef MS_WINDOWS
PyErr_SetFromWindowsErrWithFilename(0, "protocol");
#else
PyErr_SetFromErrnoWithFilename(PyExc_OSError, "protocol");
#endif
return -1;
}
}
#else
proto = 0;
#endif
}
}
else {
/* No fd, default to AF_INET and SOCK_STREAM */
if (family == -1) {
family = AF_INET;
}
if (type == -1) {
type = SOCK_STREAM;
}
if (proto == -1) {
proto = 0;
}
#ifdef MS_WINDOWS
/* Windows implementation */
#ifndef WSA_FLAG_NO_HANDLE_INHERIT