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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 collections import namedtuple
from socket import CMSG_SPACE, SCM_RIGHTS, socket as Socket
from typing import List, Tuple
__all__ = ["sendmsg", "recvmsg", "getSocketFamily", "SCM_RIGHTS"]
ReceivedMessage = namedtuple("ReceivedMessage", ["data", "ancillary", "flags"])
def sendmsg(
socket: Socket,
data: bytes,
ancillary: List[Tuple[int, int, bytes]] = [],
flags: int = 0,
) -> int:
"""
Send a message on a socket.
@param socket: The socket to send the message on.
@param data: Bytes to write to the socket.
@param ancillary: Extra data to send over the socket outside of the normal
datagram or stream mechanism. By default no ancillary data is sent.
@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.
@return: The return value of the underlying syscall, if it succeeds.
"""
return socket.sendmsg([data], ancillary, flags)
def recvmsg(
socket: Socket, maxSize: int = 8192, cmsgSize: int = 4096, flags: int = 0
) -> ReceivedMessage:
"""
Receive a message on a socket.
@param socket: The socket to receive the message on.
@param maxSize: The maximum number of bytes to receive from the socket using
the datagram or stream mechanism. The default maximum is 8192.
@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.
@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.
@return: A named 3-tuple of the bytes received using the datagram/stream
mechanism, a L{list} of L{tuple}s giving ancillary received data, and
flags as an L{int} describing the data received.
"""
# In Twisted's _sendmsg.c, the csmg_space was 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]
return ReceivedMessage(data=data, ancillary=ancillary, flags=flags)
def getSocketFamily(socket: Socket) -> int:
"""
Return the family of the given socket.
@param socket: The socket to get the family of.
"""
return socket.family
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