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# -*- test-case-name: twisted.test.test_sendmsg -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
sendmsg(2) and recvmsg(2) support for Python.
"""
from __future__ import absolute_import, division
from collections import namedtuple
from twisted.python.compat import _PY3
__all__ = ["sendmsg", "recvmsg", "getSocketFamily", "SCM_RIGHTS"]
if not _PY3:
from twisted.python._sendmsg import send1msg, recv1msg
from twisted.python._sendmsg import getsockfam, SCM_RIGHTS
__all__ += ["send1msg", "recv1msg", "getsockfam"]
else:
from socket import SCM_RIGHTS, CMSG_SPACE
RecievedMessage = namedtuple('RecievedMessage', ['data', 'ancillary', 'flags'])
def sendmsg(socket, data, ancillary=[], flags=0):
"""
Send a message on a socket.
@param socket: The socket to send the message on.
@type socket: L{socket.socket}
@param data: Bytes to write to the socket.
@type data: bytes
@param ancillary: Extra data to send over the socket outside of the normal
datagram or stream mechanism. By default no ancillary data is sent.
@type ancillary: C{list} of C{tuple} of C{int}, C{int}, and C{bytes}.
@param flags: Flags to affect how the message is sent. See the C{MSG_}
constants in the sendmsg(2) manual page. By default no flags are set.
@type flags: C{int}
@return: The return value of the underlying syscall, if it succeeds.
"""
if _PY3:
return socket.sendmsg([data], ancillary, flags)
else:
return send1msg(socket.fileno(), data, flags, ancillary)
def recvmsg(socket, maxSize=8192, cmsgSize=4096, flags=0):
"""
Recieve a message on a socket.
@param socket: The socket to recieve the message on.
@type socket: L{socket.socket}
@param maxSize: The maximum number of bytes to receive from the socket using
the datagram or stream mechanism. The default maximum is 8192.
@type maxSize: L{int}
@param cmsgSize: The maximum number of bytes to receive from the socket
outside of the normal datagram or stream mechanism. The default maximum
is 4096.
@type cmsgSize: L{int}
@param flags: Flags to affect how the message is sent. See the C{MSG_}
constants in the sendmsg(2) manual page. By default no flags are set.
@type flags: L{int}
@return: A named 3-tuple of the bytes recieved using the datagram/stream
mechanism, a L{list} of L{tuple}s giving ancillary recieved data, and
flags as an L{int} describing the data recieved.
"""
if _PY3:
# In Twisted's sendmsg.c, the csmg_space is defined as:
# int cmsg_size = 4096;
# cmsg_space = CMSG_SPACE(cmsg_size);
# Since the default in Python 3's socket is 0, we need to define our
# own default of 4096. -hawkie
data, ancillary, flags = socket.recvmsg(
maxSize, CMSG_SPACE(cmsgSize), flags)[0:3]
else:
data, flags, ancillary = recv1msg(
socket.fileno(), flags, maxSize, cmsgSize)
return RecievedMessage(data=data, ancillary=ancillary, flags=flags)
def getSocketFamily(socket):
"""
Return the family of the given socket.
@param socket: The socket to get the family of.
@type socket: L{socket.socket}
@rtype: L{int}
"""
if _PY3:
return socket.family
else:
return getsockfam(socket.fileno())
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