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"""Various low-level utility functions for sockets."""
__all__ = ['set_tcp_keepalive', 'set_nonblocking', 'set_cloexec']
import sys
import os
import socket
try:
import fcntl
except ImportError:
pass
__all__ = ['set_tcp_keepalive', 'set_nonblocking', 'set_cloexec']
def set_tcp_keepalive(fd, keepalive = True,
tcp_keepidle = 4 * 60,
tcp_keepcnt = 4,
tcp_keepintvl = 15):
"""Turn on TCP keepalive. The fd can be either numeric or socket
object with 'fileno' method.
OS defaults for SO_KEEPALIVE=1:
- Linux: (7200, 9, 75) - can configure all.
- MacOS: (7200, 8, 75) - can configure only tcp_keepidle.
- Win32: (7200, 5|10, 1) - can configure tcp_keepidle and tcp_keepintvl.
Our defaults: (240, 4, 15).
>>> import socket
>>> s = socket.socket()
>>> set_tcp_keepalive(s)
"""
# usable on this OS?
if not hasattr(socket, 'SO_KEEPALIVE') or not hasattr(socket, 'fromfd'):
return
# need socket object
if isinstance(fd, socket.SocketType):
s = fd
else:
if hasattr(fd, 'fileno'):
fd = fd.fileno()
s = socket.fromfd(fd, socket.AF_INET, socket.SOCK_STREAM)
# skip if unix socket
if type(s.getsockname()) != type(()):
return
# no keepalive?
if not keepalive:
s.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 0)
return
# basic keepalive
s.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
# detect available options
TCP_KEEPCNT = getattr(socket, 'TCP_KEEPCNT', None)
TCP_KEEPINTVL = getattr(socket, 'TCP_KEEPINTVL', None)
TCP_KEEPIDLE = getattr(socket, 'TCP_KEEPIDLE', None)
TCP_KEEPALIVE = getattr(socket, 'TCP_KEEPALIVE', None)
SIO_KEEPALIVE_VALS = getattr(socket, 'SIO_KEEPALIVE_VALS', None)
if TCP_KEEPIDLE is None and TCP_KEEPALIVE is None and sys.platform == 'darwin':
TCP_KEEPALIVE = 0x10
# configure
if TCP_KEEPCNT is not None:
s.setsockopt(socket.IPPROTO_TCP, TCP_KEEPCNT, tcp_keepcnt)
if TCP_KEEPINTVL is not None:
s.setsockopt(socket.IPPROTO_TCP, TCP_KEEPINTVL, tcp_keepintvl)
if TCP_KEEPIDLE is not None:
s.setsockopt(socket.IPPROTO_TCP, TCP_KEEPIDLE, tcp_keepidle)
elif TCP_KEEPALIVE is not None:
s.setsockopt(socket.IPPROTO_TCP, TCP_KEEPALIVE, tcp_keepidle)
elif SIO_KEEPALIVE_VALS is not None:
s.ioctl(SIO_KEEPALIVE_VALS, (1, tcp_keepidle*1000, tcp_keepintvl*1000))
def set_nonblocking(fd, onoff=True):
"""Toggle the O_NONBLOCK flag.
If onoff==None then return current setting.
Actual sockets from 'socket' module should use .setblocking() method,
this is for situations where it is not available. Eg. pipes
from 'subprocess' module.
>>> import socket
>>> s = socket.socket()
>>> set_nonblocking(s, None)
False
>>> set_nonblocking(s, 1)
>>> set_nonblocking(s, None)
True
"""
flags = fcntl.fcntl(fd, fcntl.F_GETFL)
if onoff is None:
return (flags & os.O_NONBLOCK) > 0
if onoff:
flags |= os.O_NONBLOCK
else:
flags &= ~os.O_NONBLOCK
fcntl.fcntl(fd, fcntl.F_SETFL, flags)
def set_cloexec(fd, onoff=True):
"""Toggle the FD_CLOEXEC flag.
If onoff==None then return current setting.
Some libraries do it automatically (eg. libpq).
Others do not (Python stdlib).
>>> import os
>>> f = open(os.devnull, 'rb')
>>> set_cloexec(f, None)
False
>>> set_cloexec(f, True)
>>> set_cloexec(f, None)
True
>>> import socket
>>> s = socket.socket()
>>> set_cloexec(s, None)
False
>>> set_cloexec(s)
>>> set_cloexec(s, None)
True
"""
flags = fcntl.fcntl(fd, fcntl.F_GETFD)
if onoff is None:
return (flags & fcntl.FD_CLOEXEC) > 0
if onoff:
flags |= fcntl.FD_CLOEXEC
else:
flags &= ~fcntl.FD_CLOEXEC
fcntl.fcntl(fd, fcntl.F_SETFD, flags)
if __name__ == '__main__':
import doctest
doctest.testmod()
|
