mirror of
https://github.com/python/cpython.git
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0b4e090422
Follow-up of gh-107219. * Only close the connection writer on Windows. * Also use existing constant _winapi.ERROR_OPERATION_ABORTED instead of WSA_OPERATION_ABORTED.
1177 lines
40 KiB
Python
1177 lines
40 KiB
Python
#
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# A higher level module for using sockets (or Windows named pipes)
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#
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# multiprocessing/connection.py
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#
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# Copyright (c) 2006-2008, R Oudkerk
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# Licensed to PSF under a Contributor Agreement.
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#
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__all__ = [ 'Client', 'Listener', 'Pipe', 'wait' ]
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import errno
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import io
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import os
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import sys
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import socket
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import struct
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import time
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import tempfile
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import itertools
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import _multiprocessing
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from . import util
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from . import AuthenticationError, BufferTooShort
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from .context import reduction
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_ForkingPickler = reduction.ForkingPickler
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try:
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import _winapi
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from _winapi import WAIT_OBJECT_0, WAIT_ABANDONED_0, WAIT_TIMEOUT, INFINITE
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except ImportError:
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if sys.platform == 'win32':
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raise
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_winapi = None
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#
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#
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#
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BUFSIZE = 8192
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# A very generous timeout when it comes to local connections...
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CONNECTION_TIMEOUT = 20.
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_mmap_counter = itertools.count()
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default_family = 'AF_INET'
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families = ['AF_INET']
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if hasattr(socket, 'AF_UNIX'):
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default_family = 'AF_UNIX'
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families += ['AF_UNIX']
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if sys.platform == 'win32':
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default_family = 'AF_PIPE'
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families += ['AF_PIPE']
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def _init_timeout(timeout=CONNECTION_TIMEOUT):
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return time.monotonic() + timeout
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def _check_timeout(t):
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return time.monotonic() > t
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#
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#
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#
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def arbitrary_address(family):
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'''
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Return an arbitrary free address for the given family
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'''
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if family == 'AF_INET':
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return ('localhost', 0)
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elif family == 'AF_UNIX':
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return tempfile.mktemp(prefix='listener-', dir=util.get_temp_dir())
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elif family == 'AF_PIPE':
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return tempfile.mktemp(prefix=r'\\.\pipe\pyc-%d-%d-' %
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(os.getpid(), next(_mmap_counter)), dir="")
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else:
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raise ValueError('unrecognized family')
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def _validate_family(family):
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'''
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Checks if the family is valid for the current environment.
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'''
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if sys.platform != 'win32' and family == 'AF_PIPE':
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raise ValueError('Family %s is not recognized.' % family)
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if sys.platform == 'win32' and family == 'AF_UNIX':
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# double check
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if not hasattr(socket, family):
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raise ValueError('Family %s is not recognized.' % family)
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def address_type(address):
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'''
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Return the types of the address
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This can be 'AF_INET', 'AF_UNIX', or 'AF_PIPE'
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'''
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if type(address) == tuple:
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return 'AF_INET'
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elif type(address) is str and address.startswith('\\\\'):
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return 'AF_PIPE'
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elif type(address) is str or util.is_abstract_socket_namespace(address):
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return 'AF_UNIX'
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else:
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raise ValueError('address type of %r unrecognized' % address)
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#
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# Connection classes
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#
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class _ConnectionBase:
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_handle = None
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def __init__(self, handle, readable=True, writable=True):
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handle = handle.__index__()
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if handle < 0:
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raise ValueError("invalid handle")
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if not readable and not writable:
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raise ValueError(
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"at least one of `readable` and `writable` must be True")
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self._handle = handle
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self._readable = readable
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self._writable = writable
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# XXX should we use util.Finalize instead of a __del__?
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def __del__(self):
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if self._handle is not None:
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self._close()
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def _check_closed(self):
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if self._handle is None:
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raise OSError("handle is closed")
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def _check_readable(self):
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if not self._readable:
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raise OSError("connection is write-only")
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def _check_writable(self):
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if not self._writable:
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raise OSError("connection is read-only")
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def _bad_message_length(self):
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if self._writable:
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self._readable = False
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else:
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self.close()
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raise OSError("bad message length")
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@property
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def closed(self):
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"""True if the connection is closed"""
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return self._handle is None
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@property
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def readable(self):
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"""True if the connection is readable"""
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return self._readable
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@property
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def writable(self):
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"""True if the connection is writable"""
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return self._writable
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def fileno(self):
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"""File descriptor or handle of the connection"""
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self._check_closed()
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return self._handle
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def close(self):
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"""Close the connection"""
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if self._handle is not None:
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try:
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self._close()
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finally:
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self._handle = None
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def send_bytes(self, buf, offset=0, size=None):
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"""Send the bytes data from a bytes-like object"""
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self._check_closed()
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self._check_writable()
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m = memoryview(buf)
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if m.itemsize > 1:
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m = m.cast('B')
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n = m.nbytes
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if offset < 0:
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raise ValueError("offset is negative")
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if n < offset:
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raise ValueError("buffer length < offset")
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if size is None:
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size = n - offset
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elif size < 0:
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raise ValueError("size is negative")
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elif offset + size > n:
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raise ValueError("buffer length < offset + size")
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self._send_bytes(m[offset:offset + size])
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def send(self, obj):
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"""Send a (picklable) object"""
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self._check_closed()
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self._check_writable()
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self._send_bytes(_ForkingPickler.dumps(obj))
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def recv_bytes(self, maxlength=None):
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"""
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Receive bytes data as a bytes object.
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"""
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self._check_closed()
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self._check_readable()
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if maxlength is not None and maxlength < 0:
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raise ValueError("negative maxlength")
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buf = self._recv_bytes(maxlength)
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if buf is None:
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self._bad_message_length()
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return buf.getvalue()
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def recv_bytes_into(self, buf, offset=0):
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"""
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Receive bytes data into a writeable bytes-like object.
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Return the number of bytes read.
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"""
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self._check_closed()
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self._check_readable()
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with memoryview(buf) as m:
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# Get bytesize of arbitrary buffer
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itemsize = m.itemsize
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bytesize = itemsize * len(m)
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if offset < 0:
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raise ValueError("negative offset")
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elif offset > bytesize:
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raise ValueError("offset too large")
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result = self._recv_bytes()
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size = result.tell()
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if bytesize < offset + size:
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raise BufferTooShort(result.getvalue())
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# Message can fit in dest
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result.seek(0)
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result.readinto(m[offset // itemsize :
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(offset + size) // itemsize])
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return size
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def recv(self):
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"""Receive a (picklable) object"""
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self._check_closed()
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self._check_readable()
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buf = self._recv_bytes()
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return _ForkingPickler.loads(buf.getbuffer())
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def poll(self, timeout=0.0):
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"""Whether there is any input available to be read"""
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self._check_closed()
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self._check_readable()
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return self._poll(timeout)
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def __enter__(self):
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return self
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def __exit__(self, exc_type, exc_value, exc_tb):
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self.close()
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if _winapi:
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class PipeConnection(_ConnectionBase):
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"""
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Connection class based on a Windows named pipe.
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Overlapped I/O is used, so the handles must have been created
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with FILE_FLAG_OVERLAPPED.
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"""
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_got_empty_message = False
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_send_ov = None
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def _close(self, _CloseHandle=_winapi.CloseHandle):
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ov = self._send_ov
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if ov is not None:
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# Interrupt WaitForMultipleObjects() in _send_bytes()
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ov.cancel()
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_CloseHandle(self._handle)
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def _send_bytes(self, buf):
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if self._send_ov is not None:
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# A connection should only be used by a single thread
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raise ValueError("concurrent send_bytes() calls "
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"are not supported")
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ov, err = _winapi.WriteFile(self._handle, buf, overlapped=True)
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self._send_ov = ov
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try:
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if err == _winapi.ERROR_IO_PENDING:
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waitres = _winapi.WaitForMultipleObjects(
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[ov.event], False, INFINITE)
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assert waitres == WAIT_OBJECT_0
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except:
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ov.cancel()
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raise
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finally:
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self._send_ov = None
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nwritten, err = ov.GetOverlappedResult(True)
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if err == _winapi.ERROR_OPERATION_ABORTED:
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# close() was called by another thread while
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# WaitForMultipleObjects() was waiting for the overlapped
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# operation.
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raise OSError(errno.EPIPE, "handle is closed")
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assert err == 0
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assert nwritten == len(buf)
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def _recv_bytes(self, maxsize=None):
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if self._got_empty_message:
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self._got_empty_message = False
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return io.BytesIO()
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else:
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bsize = 128 if maxsize is None else min(maxsize, 128)
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try:
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ov, err = _winapi.ReadFile(self._handle, bsize,
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overlapped=True)
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try:
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if err == _winapi.ERROR_IO_PENDING:
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waitres = _winapi.WaitForMultipleObjects(
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[ov.event], False, INFINITE)
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assert waitres == WAIT_OBJECT_0
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except:
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ov.cancel()
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raise
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finally:
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nread, err = ov.GetOverlappedResult(True)
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if err == 0:
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f = io.BytesIO()
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f.write(ov.getbuffer())
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return f
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elif err == _winapi.ERROR_MORE_DATA:
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return self._get_more_data(ov, maxsize)
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except OSError as e:
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if e.winerror == _winapi.ERROR_BROKEN_PIPE:
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raise EOFError
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else:
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raise
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raise RuntimeError("shouldn't get here; expected KeyboardInterrupt")
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def _poll(self, timeout):
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if (self._got_empty_message or
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_winapi.PeekNamedPipe(self._handle)[0] != 0):
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return True
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return bool(wait([self], timeout))
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def _get_more_data(self, ov, maxsize):
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buf = ov.getbuffer()
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f = io.BytesIO()
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f.write(buf)
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left = _winapi.PeekNamedPipe(self._handle)[1]
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assert left > 0
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if maxsize is not None and len(buf) + left > maxsize:
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self._bad_message_length()
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ov, err = _winapi.ReadFile(self._handle, left, overlapped=True)
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rbytes, err = ov.GetOverlappedResult(True)
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assert err == 0
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assert rbytes == left
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f.write(ov.getbuffer())
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return f
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class Connection(_ConnectionBase):
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"""
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Connection class based on an arbitrary file descriptor (Unix only), or
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a socket handle (Windows).
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"""
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if _winapi:
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def _close(self, _close=_multiprocessing.closesocket):
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_close(self._handle)
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_write = _multiprocessing.send
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_read = _multiprocessing.recv
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else:
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def _close(self, _close=os.close):
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_close(self._handle)
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_write = os.write
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_read = os.read
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def _send(self, buf, write=_write):
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remaining = len(buf)
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while True:
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n = write(self._handle, buf)
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remaining -= n
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if remaining == 0:
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break
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buf = buf[n:]
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def _recv(self, size, read=_read):
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buf = io.BytesIO()
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handle = self._handle
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remaining = size
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while remaining > 0:
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chunk = read(handle, remaining)
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n = len(chunk)
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if n == 0:
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if remaining == size:
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raise EOFError
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else:
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raise OSError("got end of file during message")
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buf.write(chunk)
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remaining -= n
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return buf
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def _send_bytes(self, buf):
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n = len(buf)
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if n > 0x7fffffff:
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pre_header = struct.pack("!i", -1)
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header = struct.pack("!Q", n)
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self._send(pre_header)
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self._send(header)
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self._send(buf)
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else:
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# For wire compatibility with 3.7 and lower
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header = struct.pack("!i", n)
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if n > 16384:
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# The payload is large so Nagle's algorithm won't be triggered
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# and we'd better avoid the cost of concatenation.
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self._send(header)
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self._send(buf)
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else:
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# Issue #20540: concatenate before sending, to avoid delays due
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# to Nagle's algorithm on a TCP socket.
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# Also note we want to avoid sending a 0-length buffer separately,
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# to avoid "broken pipe" errors if the other end closed the pipe.
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self._send(header + buf)
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def _recv_bytes(self, maxsize=None):
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buf = self._recv(4)
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size, = struct.unpack("!i", buf.getvalue())
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if size == -1:
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buf = self._recv(8)
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size, = struct.unpack("!Q", buf.getvalue())
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if maxsize is not None and size > maxsize:
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return None
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return self._recv(size)
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def _poll(self, timeout):
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r = wait([self], timeout)
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return bool(r)
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#
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# Public functions
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#
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class Listener(object):
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'''
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Returns a listener object.
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This is a wrapper for a bound socket which is 'listening' for
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connections, or for a Windows named pipe.
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'''
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def __init__(self, address=None, family=None, backlog=1, authkey=None):
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family = family or (address and address_type(address)) \
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or default_family
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address = address or arbitrary_address(family)
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_validate_family(family)
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if family == 'AF_PIPE':
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self._listener = PipeListener(address, backlog)
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else:
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self._listener = SocketListener(address, family, backlog)
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if authkey is not None and not isinstance(authkey, bytes):
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raise TypeError('authkey should be a byte string')
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self._authkey = authkey
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def accept(self):
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'''
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Accept a connection on the bound socket or named pipe of `self`.
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Returns a `Connection` object.
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'''
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if self._listener is None:
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raise OSError('listener is closed')
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c = self._listener.accept()
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if self._authkey:
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deliver_challenge(c, self._authkey)
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answer_challenge(c, self._authkey)
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return c
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def close(self):
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'''
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Close the bound socket or named pipe of `self`.
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'''
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listener = self._listener
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if listener is not None:
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self._listener = None
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listener.close()
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@property
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def address(self):
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return self._listener._address
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@property
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def last_accepted(self):
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return self._listener._last_accepted
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def __enter__(self):
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return self
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def __exit__(self, exc_type, exc_value, exc_tb):
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self.close()
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def Client(address, family=None, authkey=None):
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'''
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Returns a connection to the address of a `Listener`
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'''
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family = family or address_type(address)
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_validate_family(family)
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if family == 'AF_PIPE':
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c = PipeClient(address)
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else:
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c = SocketClient(address)
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if authkey is not None and not isinstance(authkey, bytes):
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raise TypeError('authkey should be a byte string')
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if authkey is not None:
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answer_challenge(c, authkey)
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deliver_challenge(c, authkey)
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return c
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if sys.platform != 'win32':
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def Pipe(duplex=True):
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'''
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Returns pair of connection objects at either end of a pipe
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'''
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if duplex:
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s1, s2 = socket.socketpair()
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s1.setblocking(True)
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s2.setblocking(True)
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c1 = Connection(s1.detach())
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c2 = Connection(s2.detach())
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else:
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fd1, fd2 = os.pipe()
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c1 = Connection(fd1, writable=False)
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c2 = Connection(fd2, readable=False)
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return c1, c2
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else:
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def Pipe(duplex=True):
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'''
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Returns pair of connection objects at either end of a pipe
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'''
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address = arbitrary_address('AF_PIPE')
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if duplex:
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openmode = _winapi.PIPE_ACCESS_DUPLEX
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access = _winapi.GENERIC_READ | _winapi.GENERIC_WRITE
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obsize, ibsize = BUFSIZE, BUFSIZE
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else:
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openmode = _winapi.PIPE_ACCESS_INBOUND
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access = _winapi.GENERIC_WRITE
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obsize, ibsize = 0, BUFSIZE
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h1 = _winapi.CreateNamedPipe(
|
|
address, openmode | _winapi.FILE_FLAG_OVERLAPPED |
|
|
_winapi.FILE_FLAG_FIRST_PIPE_INSTANCE,
|
|
_winapi.PIPE_TYPE_MESSAGE | _winapi.PIPE_READMODE_MESSAGE |
|
|
_winapi.PIPE_WAIT,
|
|
1, obsize, ibsize, _winapi.NMPWAIT_WAIT_FOREVER,
|
|
# default security descriptor: the handle cannot be inherited
|
|
_winapi.NULL
|
|
)
|
|
h2 = _winapi.CreateFile(
|
|
address, access, 0, _winapi.NULL, _winapi.OPEN_EXISTING,
|
|
_winapi.FILE_FLAG_OVERLAPPED, _winapi.NULL
|
|
)
|
|
_winapi.SetNamedPipeHandleState(
|
|
h2, _winapi.PIPE_READMODE_MESSAGE, None, None
|
|
)
|
|
|
|
overlapped = _winapi.ConnectNamedPipe(h1, overlapped=True)
|
|
_, err = overlapped.GetOverlappedResult(True)
|
|
assert err == 0
|
|
|
|
c1 = PipeConnection(h1, writable=duplex)
|
|
c2 = PipeConnection(h2, readable=duplex)
|
|
|
|
return c1, c2
|
|
|
|
#
|
|
# Definitions for connections based on sockets
|
|
#
|
|
|
|
class SocketListener(object):
|
|
'''
|
|
Representation of a socket which is bound to an address and listening
|
|
'''
|
|
def __init__(self, address, family, backlog=1):
|
|
self._socket = socket.socket(getattr(socket, family))
|
|
try:
|
|
# SO_REUSEADDR has different semantics on Windows (issue #2550).
|
|
if os.name == 'posix':
|
|
self._socket.setsockopt(socket.SOL_SOCKET,
|
|
socket.SO_REUSEADDR, 1)
|
|
self._socket.setblocking(True)
|
|
self._socket.bind(address)
|
|
self._socket.listen(backlog)
|
|
self._address = self._socket.getsockname()
|
|
except OSError:
|
|
self._socket.close()
|
|
raise
|
|
self._family = family
|
|
self._last_accepted = None
|
|
|
|
if family == 'AF_UNIX' and not util.is_abstract_socket_namespace(address):
|
|
# Linux abstract socket namespaces do not need to be explicitly unlinked
|
|
self._unlink = util.Finalize(
|
|
self, os.unlink, args=(address,), exitpriority=0
|
|
)
|
|
else:
|
|
self._unlink = None
|
|
|
|
def accept(self):
|
|
s, self._last_accepted = self._socket.accept()
|
|
s.setblocking(True)
|
|
return Connection(s.detach())
|
|
|
|
def close(self):
|
|
try:
|
|
self._socket.close()
|
|
finally:
|
|
unlink = self._unlink
|
|
if unlink is not None:
|
|
self._unlink = None
|
|
unlink()
|
|
|
|
|
|
def SocketClient(address):
|
|
'''
|
|
Return a connection object connected to the socket given by `address`
|
|
'''
|
|
family = address_type(address)
|
|
with socket.socket( getattr(socket, family) ) as s:
|
|
s.setblocking(True)
|
|
s.connect(address)
|
|
return Connection(s.detach())
|
|
|
|
#
|
|
# Definitions for connections based on named pipes
|
|
#
|
|
|
|
if sys.platform == 'win32':
|
|
|
|
class PipeListener(object):
|
|
'''
|
|
Representation of a named pipe
|
|
'''
|
|
def __init__(self, address, backlog=None):
|
|
self._address = address
|
|
self._handle_queue = [self._new_handle(first=True)]
|
|
|
|
self._last_accepted = None
|
|
util.sub_debug('listener created with address=%r', self._address)
|
|
self.close = util.Finalize(
|
|
self, PipeListener._finalize_pipe_listener,
|
|
args=(self._handle_queue, self._address), exitpriority=0
|
|
)
|
|
|
|
def _new_handle(self, first=False):
|
|
flags = _winapi.PIPE_ACCESS_DUPLEX | _winapi.FILE_FLAG_OVERLAPPED
|
|
if first:
|
|
flags |= _winapi.FILE_FLAG_FIRST_PIPE_INSTANCE
|
|
return _winapi.CreateNamedPipe(
|
|
self._address, flags,
|
|
_winapi.PIPE_TYPE_MESSAGE | _winapi.PIPE_READMODE_MESSAGE |
|
|
_winapi.PIPE_WAIT,
|
|
_winapi.PIPE_UNLIMITED_INSTANCES, BUFSIZE, BUFSIZE,
|
|
_winapi.NMPWAIT_WAIT_FOREVER, _winapi.NULL
|
|
)
|
|
|
|
def accept(self):
|
|
self._handle_queue.append(self._new_handle())
|
|
handle = self._handle_queue.pop(0)
|
|
try:
|
|
ov = _winapi.ConnectNamedPipe(handle, overlapped=True)
|
|
except OSError as e:
|
|
if e.winerror != _winapi.ERROR_NO_DATA:
|
|
raise
|
|
# ERROR_NO_DATA can occur if a client has already connected,
|
|
# written data and then disconnected -- see Issue 14725.
|
|
else:
|
|
try:
|
|
res = _winapi.WaitForMultipleObjects(
|
|
[ov.event], False, INFINITE)
|
|
except:
|
|
ov.cancel()
|
|
_winapi.CloseHandle(handle)
|
|
raise
|
|
finally:
|
|
_, err = ov.GetOverlappedResult(True)
|
|
assert err == 0
|
|
return PipeConnection(handle)
|
|
|
|
@staticmethod
|
|
def _finalize_pipe_listener(queue, address):
|
|
util.sub_debug('closing listener with address=%r', address)
|
|
for handle in queue:
|
|
_winapi.CloseHandle(handle)
|
|
|
|
def PipeClient(address):
|
|
'''
|
|
Return a connection object connected to the pipe given by `address`
|
|
'''
|
|
t = _init_timeout()
|
|
while 1:
|
|
try:
|
|
_winapi.WaitNamedPipe(address, 1000)
|
|
h = _winapi.CreateFile(
|
|
address, _winapi.GENERIC_READ | _winapi.GENERIC_WRITE,
|
|
0, _winapi.NULL, _winapi.OPEN_EXISTING,
|
|
_winapi.FILE_FLAG_OVERLAPPED, _winapi.NULL
|
|
)
|
|
except OSError as e:
|
|
if e.winerror not in (_winapi.ERROR_SEM_TIMEOUT,
|
|
_winapi.ERROR_PIPE_BUSY) or _check_timeout(t):
|
|
raise
|
|
else:
|
|
break
|
|
else:
|
|
raise
|
|
|
|
_winapi.SetNamedPipeHandleState(
|
|
h, _winapi.PIPE_READMODE_MESSAGE, None, None
|
|
)
|
|
return PipeConnection(h)
|
|
|
|
#
|
|
# Authentication stuff
|
|
#
|
|
|
|
MESSAGE_LENGTH = 40 # MUST be > 20
|
|
|
|
_CHALLENGE = b'#CHALLENGE#'
|
|
_WELCOME = b'#WELCOME#'
|
|
_FAILURE = b'#FAILURE#'
|
|
|
|
# multiprocessing.connection Authentication Handshake Protocol Description
|
|
# (as documented for reference after reading the existing code)
|
|
# =============================================================================
|
|
#
|
|
# On Windows: native pipes with "overlapped IO" are used to send the bytes,
|
|
# instead of the length prefix SIZE scheme described below. (ie: the OS deals
|
|
# with message sizes for us)
|
|
#
|
|
# Protocol error behaviors:
|
|
#
|
|
# On POSIX, any failure to receive the length prefix into SIZE, for SIZE greater
|
|
# than the requested maxsize to receive, or receiving fewer than SIZE bytes
|
|
# results in the connection being closed and auth to fail.
|
|
#
|
|
# On Windows, receiving too few bytes is never a low level _recv_bytes read
|
|
# error, receiving too many will trigger an error only if receive maxsize
|
|
# value was larger than 128 OR the if the data arrived in smaller pieces.
|
|
#
|
|
# Serving side Client side
|
|
# ------------------------------ ---------------------------------------
|
|
# 0. Open a connection on the pipe.
|
|
# 1. Accept connection.
|
|
# 2. Random 20+ bytes -> MESSAGE
|
|
# Modern servers always send
|
|
# more than 20 bytes and include
|
|
# a {digest} prefix on it with
|
|
# their preferred HMAC digest.
|
|
# Legacy ones send ==20 bytes.
|
|
# 3. send 4 byte length (net order)
|
|
# prefix followed by:
|
|
# b'#CHALLENGE#' + MESSAGE
|
|
# 4. Receive 4 bytes, parse as network byte
|
|
# order integer. If it is -1, receive an
|
|
# additional 8 bytes, parse that as network
|
|
# byte order. The result is the length of
|
|
# the data that follows -> SIZE.
|
|
# 5. Receive min(SIZE, 256) bytes -> M1
|
|
# 6. Assert that M1 starts with:
|
|
# b'#CHALLENGE#'
|
|
# 7. Strip that prefix from M1 into -> M2
|
|
# 7.1. Parse M2: if it is exactly 20 bytes in
|
|
# length this indicates a legacy server
|
|
# supporting only HMAC-MD5. Otherwise the
|
|
# 7.2. preferred digest is looked up from an
|
|
# expected "{digest}" prefix on M2. No prefix
|
|
# or unsupported digest? <- AuthenticationError
|
|
# 7.3. Put divined algorithm name in -> D_NAME
|
|
# 8. Compute HMAC-D_NAME of AUTHKEY, M2 -> C_DIGEST
|
|
# 9. Send 4 byte length prefix (net order)
|
|
# followed by C_DIGEST bytes.
|
|
# 10. Receive 4 or 4+8 byte length
|
|
# prefix (#4 dance) -> SIZE.
|
|
# 11. Receive min(SIZE, 256) -> C_D.
|
|
# 11.1. Parse C_D: legacy servers
|
|
# accept it as is, "md5" -> D_NAME
|
|
# 11.2. modern servers check the length
|
|
# of C_D, IF it is 16 bytes?
|
|
# 11.2.1. "md5" -> D_NAME
|
|
# and skip to step 12.
|
|
# 11.3. longer? expect and parse a "{digest}"
|
|
# prefix into -> D_NAME.
|
|
# Strip the prefix and store remaining
|
|
# bytes in -> C_D.
|
|
# 11.4. Don't like D_NAME? <- AuthenticationError
|
|
# 12. Compute HMAC-D_NAME of AUTHKEY,
|
|
# MESSAGE into -> M_DIGEST.
|
|
# 13. Compare M_DIGEST == C_D:
|
|
# 14a: Match? Send length prefix &
|
|
# b'#WELCOME#'
|
|
# <- RETURN
|
|
# 14b: Mismatch? Send len prefix &
|
|
# b'#FAILURE#'
|
|
# <- CLOSE & AuthenticationError
|
|
# 15. Receive 4 or 4+8 byte length prefix (net
|
|
# order) again as in #4 into -> SIZE.
|
|
# 16. Receive min(SIZE, 256) bytes -> M3.
|
|
# 17. Compare M3 == b'#WELCOME#':
|
|
# 17a. Match? <- RETURN
|
|
# 17b. Mismatch? <- CLOSE & AuthenticationError
|
|
#
|
|
# If this RETURNed, the connection remains open: it has been authenticated.
|
|
#
|
|
# Length prefixes are used consistently. Even on the legacy protocol, this
|
|
# was good fortune and allowed us to evolve the protocol by using the length
|
|
# of the opening challenge or length of the returned digest as a signal as
|
|
# to which protocol the other end supports.
|
|
|
|
_ALLOWED_DIGESTS = frozenset(
|
|
{b'md5', b'sha256', b'sha384', b'sha3_256', b'sha3_384'})
|
|
_MAX_DIGEST_LEN = max(len(_) for _ in _ALLOWED_DIGESTS)
|
|
|
|
# Old hmac-md5 only server versions from Python <=3.11 sent a message of this
|
|
# length. It happens to not match the length of any supported digest so we can
|
|
# use a message of this length to indicate that we should work in backwards
|
|
# compatible md5-only mode without a {digest_name} prefix on our response.
|
|
_MD5ONLY_MESSAGE_LENGTH = 20
|
|
_MD5_DIGEST_LEN = 16
|
|
_LEGACY_LENGTHS = (_MD5ONLY_MESSAGE_LENGTH, _MD5_DIGEST_LEN)
|
|
|
|
|
|
def _get_digest_name_and_payload(message: bytes) -> (str, bytes):
|
|
"""Returns a digest name and the payload for a response hash.
|
|
|
|
If a legacy protocol is detected based on the message length
|
|
or contents the digest name returned will be empty to indicate
|
|
legacy mode where MD5 and no digest prefix should be sent.
|
|
"""
|
|
# modern message format: b"{digest}payload" longer than 20 bytes
|
|
# legacy message format: 16 or 20 byte b"payload"
|
|
if len(message) in _LEGACY_LENGTHS:
|
|
# Either this was a legacy server challenge, or we're processing
|
|
# a reply from a legacy client that sent an unprefixed 16-byte
|
|
# HMAC-MD5 response. All messages using the modern protocol will
|
|
# be longer than either of these lengths.
|
|
return '', message
|
|
if (message.startswith(b'{') and
|
|
(curly := message.find(b'}', 1, _MAX_DIGEST_LEN+2)) > 0):
|
|
digest = message[1:curly]
|
|
if digest in _ALLOWED_DIGESTS:
|
|
payload = message[curly+1:]
|
|
return digest.decode('ascii'), payload
|
|
raise AuthenticationError(
|
|
'unsupported message length, missing digest prefix, '
|
|
f'or unsupported digest: {message=}')
|
|
|
|
|
|
def _create_response(authkey, message):
|
|
"""Create a MAC based on authkey and message
|
|
|
|
The MAC algorithm defaults to HMAC-MD5, unless MD5 is not available or
|
|
the message has a '{digest_name}' prefix. For legacy HMAC-MD5, the response
|
|
is the raw MAC, otherwise the response is prefixed with '{digest_name}',
|
|
e.g. b'{sha256}abcdefg...'
|
|
|
|
Note: The MAC protects the entire message including the digest_name prefix.
|
|
"""
|
|
import hmac
|
|
digest_name = _get_digest_name_and_payload(message)[0]
|
|
# The MAC protects the entire message: digest header and payload.
|
|
if not digest_name:
|
|
# Legacy server without a {digest} prefix on message.
|
|
# Generate a legacy non-prefixed HMAC-MD5 reply.
|
|
try:
|
|
return hmac.new(authkey, message, 'md5').digest()
|
|
except ValueError:
|
|
# HMAC-MD5 is not available (FIPS mode?), fall back to
|
|
# HMAC-SHA2-256 modern protocol. The legacy server probably
|
|
# doesn't support it and will reject us anyways. :shrug:
|
|
digest_name = 'sha256'
|
|
# Modern protocol, indicate the digest used in the reply.
|
|
response = hmac.new(authkey, message, digest_name).digest()
|
|
return b'{%s}%s' % (digest_name.encode('ascii'), response)
|
|
|
|
|
|
def _verify_challenge(authkey, message, response):
|
|
"""Verify MAC challenge
|
|
|
|
If our message did not include a digest_name prefix, the client is allowed
|
|
to select a stronger digest_name from _ALLOWED_DIGESTS.
|
|
|
|
In case our message is prefixed, a client cannot downgrade to a weaker
|
|
algorithm, because the MAC is calculated over the entire message
|
|
including the '{digest_name}' prefix.
|
|
"""
|
|
import hmac
|
|
response_digest, response_mac = _get_digest_name_and_payload(response)
|
|
response_digest = response_digest or 'md5'
|
|
try:
|
|
expected = hmac.new(authkey, message, response_digest).digest()
|
|
except ValueError:
|
|
raise AuthenticationError(f'{response_digest=} unsupported')
|
|
if len(expected) != len(response_mac):
|
|
raise AuthenticationError(
|
|
f'expected {response_digest!r} of length {len(expected)} '
|
|
f'got {len(response_mac)}')
|
|
if not hmac.compare_digest(expected, response_mac):
|
|
raise AuthenticationError('digest received was wrong')
|
|
|
|
|
|
def deliver_challenge(connection, authkey: bytes, digest_name='sha256'):
|
|
if not isinstance(authkey, bytes):
|
|
raise ValueError(
|
|
"Authkey must be bytes, not {0!s}".format(type(authkey)))
|
|
assert MESSAGE_LENGTH > _MD5ONLY_MESSAGE_LENGTH, "protocol constraint"
|
|
message = os.urandom(MESSAGE_LENGTH)
|
|
message = b'{%s}%s' % (digest_name.encode('ascii'), message)
|
|
# Even when sending a challenge to a legacy client that does not support
|
|
# digest prefixes, they'll take the entire thing as a challenge and
|
|
# respond to it with a raw HMAC-MD5.
|
|
connection.send_bytes(_CHALLENGE + message)
|
|
response = connection.recv_bytes(256) # reject large message
|
|
try:
|
|
_verify_challenge(authkey, message, response)
|
|
except AuthenticationError:
|
|
connection.send_bytes(_FAILURE)
|
|
raise
|
|
else:
|
|
connection.send_bytes(_WELCOME)
|
|
|
|
|
|
def answer_challenge(connection, authkey: bytes):
|
|
if not isinstance(authkey, bytes):
|
|
raise ValueError(
|
|
"Authkey must be bytes, not {0!s}".format(type(authkey)))
|
|
message = connection.recv_bytes(256) # reject large message
|
|
if not message.startswith(_CHALLENGE):
|
|
raise AuthenticationError(
|
|
f'Protocol error, expected challenge: {message=}')
|
|
message = message[len(_CHALLENGE):]
|
|
if len(message) < _MD5ONLY_MESSAGE_LENGTH:
|
|
raise AuthenticationError('challenge too short: {len(message)} bytes')
|
|
digest = _create_response(authkey, message)
|
|
connection.send_bytes(digest)
|
|
response = connection.recv_bytes(256) # reject large message
|
|
if response != _WELCOME:
|
|
raise AuthenticationError('digest sent was rejected')
|
|
|
|
#
|
|
# Support for using xmlrpclib for serialization
|
|
#
|
|
|
|
class ConnectionWrapper(object):
|
|
def __init__(self, conn, dumps, loads):
|
|
self._conn = conn
|
|
self._dumps = dumps
|
|
self._loads = loads
|
|
for attr in ('fileno', 'close', 'poll', 'recv_bytes', 'send_bytes'):
|
|
obj = getattr(conn, attr)
|
|
setattr(self, attr, obj)
|
|
def send(self, obj):
|
|
s = self._dumps(obj)
|
|
self._conn.send_bytes(s)
|
|
def recv(self):
|
|
s = self._conn.recv_bytes()
|
|
return self._loads(s)
|
|
|
|
def _xml_dumps(obj):
|
|
return xmlrpclib.dumps((obj,), None, None, None, 1).encode('utf-8')
|
|
|
|
def _xml_loads(s):
|
|
(obj,), method = xmlrpclib.loads(s.decode('utf-8'))
|
|
return obj
|
|
|
|
class XmlListener(Listener):
|
|
def accept(self):
|
|
global xmlrpclib
|
|
import xmlrpc.client as xmlrpclib
|
|
obj = Listener.accept(self)
|
|
return ConnectionWrapper(obj, _xml_dumps, _xml_loads)
|
|
|
|
def XmlClient(*args, **kwds):
|
|
global xmlrpclib
|
|
import xmlrpc.client as xmlrpclib
|
|
return ConnectionWrapper(Client(*args, **kwds), _xml_dumps, _xml_loads)
|
|
|
|
#
|
|
# Wait
|
|
#
|
|
|
|
if sys.platform == 'win32':
|
|
|
|
def _exhaustive_wait(handles, timeout):
|
|
# Return ALL handles which are currently signalled. (Only
|
|
# returning the first signalled might create starvation issues.)
|
|
L = list(handles)
|
|
ready = []
|
|
while L:
|
|
res = _winapi.WaitForMultipleObjects(L, False, timeout)
|
|
if res == WAIT_TIMEOUT:
|
|
break
|
|
elif WAIT_OBJECT_0 <= res < WAIT_OBJECT_0 + len(L):
|
|
res -= WAIT_OBJECT_0
|
|
elif WAIT_ABANDONED_0 <= res < WAIT_ABANDONED_0 + len(L):
|
|
res -= WAIT_ABANDONED_0
|
|
else:
|
|
raise RuntimeError('Should not get here')
|
|
ready.append(L[res])
|
|
L = L[res+1:]
|
|
timeout = 0
|
|
return ready
|
|
|
|
_ready_errors = {_winapi.ERROR_BROKEN_PIPE, _winapi.ERROR_NETNAME_DELETED}
|
|
|
|
def wait(object_list, timeout=None):
|
|
'''
|
|
Wait till an object in object_list is ready/readable.
|
|
|
|
Returns list of those objects in object_list which are ready/readable.
|
|
'''
|
|
if timeout is None:
|
|
timeout = INFINITE
|
|
elif timeout < 0:
|
|
timeout = 0
|
|
else:
|
|
timeout = int(timeout * 1000 + 0.5)
|
|
|
|
object_list = list(object_list)
|
|
waithandle_to_obj = {}
|
|
ov_list = []
|
|
ready_objects = set()
|
|
ready_handles = set()
|
|
|
|
try:
|
|
for o in object_list:
|
|
try:
|
|
fileno = getattr(o, 'fileno')
|
|
except AttributeError:
|
|
waithandle_to_obj[o.__index__()] = o
|
|
else:
|
|
# start an overlapped read of length zero
|
|
try:
|
|
ov, err = _winapi.ReadFile(fileno(), 0, True)
|
|
except OSError as e:
|
|
ov, err = None, e.winerror
|
|
if err not in _ready_errors:
|
|
raise
|
|
if err == _winapi.ERROR_IO_PENDING:
|
|
ov_list.append(ov)
|
|
waithandle_to_obj[ov.event] = o
|
|
else:
|
|
# If o.fileno() is an overlapped pipe handle and
|
|
# err == 0 then there is a zero length message
|
|
# in the pipe, but it HAS NOT been consumed...
|
|
if ov and sys.getwindowsversion()[:2] >= (6, 2):
|
|
# ... except on Windows 8 and later, where
|
|
# the message HAS been consumed.
|
|
try:
|
|
_, err = ov.GetOverlappedResult(False)
|
|
except OSError as e:
|
|
err = e.winerror
|
|
if not err and hasattr(o, '_got_empty_message'):
|
|
o._got_empty_message = True
|
|
ready_objects.add(o)
|
|
timeout = 0
|
|
|
|
ready_handles = _exhaustive_wait(waithandle_to_obj.keys(), timeout)
|
|
finally:
|
|
# request that overlapped reads stop
|
|
for ov in ov_list:
|
|
ov.cancel()
|
|
|
|
# wait for all overlapped reads to stop
|
|
for ov in ov_list:
|
|
try:
|
|
_, err = ov.GetOverlappedResult(True)
|
|
except OSError as e:
|
|
err = e.winerror
|
|
if err not in _ready_errors:
|
|
raise
|
|
if err != _winapi.ERROR_OPERATION_ABORTED:
|
|
o = waithandle_to_obj[ov.event]
|
|
ready_objects.add(o)
|
|
if err == 0:
|
|
# If o.fileno() is an overlapped pipe handle then
|
|
# a zero length message HAS been consumed.
|
|
if hasattr(o, '_got_empty_message'):
|
|
o._got_empty_message = True
|
|
|
|
ready_objects.update(waithandle_to_obj[h] for h in ready_handles)
|
|
return [o for o in object_list if o in ready_objects]
|
|
|
|
else:
|
|
|
|
import selectors
|
|
|
|
# poll/select have the advantage of not requiring any extra file
|
|
# descriptor, contrarily to epoll/kqueue (also, they require a single
|
|
# syscall).
|
|
if hasattr(selectors, 'PollSelector'):
|
|
_WaitSelector = selectors.PollSelector
|
|
else:
|
|
_WaitSelector = selectors.SelectSelector
|
|
|
|
def wait(object_list, timeout=None):
|
|
'''
|
|
Wait till an object in object_list is ready/readable.
|
|
|
|
Returns list of those objects in object_list which are ready/readable.
|
|
'''
|
|
with _WaitSelector() as selector:
|
|
for obj in object_list:
|
|
selector.register(obj, selectors.EVENT_READ)
|
|
|
|
if timeout is not None:
|
|
deadline = time.monotonic() + timeout
|
|
|
|
while True:
|
|
ready = selector.select(timeout)
|
|
if ready:
|
|
return [key.fileobj for (key, events) in ready]
|
|
else:
|
|
if timeout is not None:
|
|
timeout = deadline - time.monotonic()
|
|
if timeout < 0:
|
|
return ready
|
|
|
|
#
|
|
# Make connection and socket objects shareable if possible
|
|
#
|
|
|
|
if sys.platform == 'win32':
|
|
def reduce_connection(conn):
|
|
handle = conn.fileno()
|
|
with socket.fromfd(handle, socket.AF_INET, socket.SOCK_STREAM) as s:
|
|
from . import resource_sharer
|
|
ds = resource_sharer.DupSocket(s)
|
|
return rebuild_connection, (ds, conn.readable, conn.writable)
|
|
def rebuild_connection(ds, readable, writable):
|
|
sock = ds.detach()
|
|
return Connection(sock.detach(), readable, writable)
|
|
reduction.register(Connection, reduce_connection)
|
|
|
|
def reduce_pipe_connection(conn):
|
|
access = ((_winapi.FILE_GENERIC_READ if conn.readable else 0) |
|
|
(_winapi.FILE_GENERIC_WRITE if conn.writable else 0))
|
|
dh = reduction.DupHandle(conn.fileno(), access)
|
|
return rebuild_pipe_connection, (dh, conn.readable, conn.writable)
|
|
def rebuild_pipe_connection(dh, readable, writable):
|
|
handle = dh.detach()
|
|
return PipeConnection(handle, readable, writable)
|
|
reduction.register(PipeConnection, reduce_pipe_connection)
|
|
|
|
else:
|
|
def reduce_connection(conn):
|
|
df = reduction.DupFd(conn.fileno())
|
|
return rebuild_connection, (df, conn.readable, conn.writable)
|
|
def rebuild_connection(df, readable, writable):
|
|
fd = df.detach()
|
|
return Connection(fd, readable, writable)
|
|
reduction.register(Connection, reduce_connection)
|