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"""Various low-level utility functions for sockets."""
import os
import socket
import sys
from typing import Optional, Union
try:
import fcntl
except ImportError:
fcntl = None # type: ignore
from .basetypes import FileDescriptorLike
__all__ = (
'set_tcp_keepalive', 'set_nonblocking', 'set_cloexec',
)
SocketLike = Union[socket.socket, FileDescriptorLike]
def set_tcp_keepalive(fd: SocketLike, keepalive: bool = True, tcp_keepidle: int = 4 *
60, tcp_keepcnt: int = 4, tcp_keepintvl: int = 15) -> None:
"""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).
"""
# 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 not isinstance(fd, int):
fd = fd.fileno()
s = socket.fromfd(fd, socket.AF_INET, socket.SOCK_STREAM)
# skip if unix socket
if getattr(socket, 'AF_UNIX', None):
if not isinstance(s.getsockname(), tuple):
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 and fcntl:
fcntl.ioctl(s.fileno(), SIO_KEEPALIVE_VALS, (1, tcp_keepidle * 1000, tcp_keepintvl * 1000)) # type: ignore
def set_nonblocking(fd: SocketLike, onoff: Optional[bool] = 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.
"""
if fcntl is None:
return onoff
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)
return onoff
def set_cloexec(fd: SocketLike, onoff: Optional[bool] = True) -> bool:
"""Toggle the FD_CLOEXEC flag.
If onoff==None then return current setting.
Some libraries do it automatically (eg. libpq).
Others do not (Python stdlib).
"""
if fcntl is None:
return 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)
return onoff
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