148 lines
3.8 KiB
Python
148 lines
3.8 KiB
Python
# Copyright (C) 2011 Jeff Forcier <jeff@bitprophet.org>
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#
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# This file is part of ssh.
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#
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# 'ssh' is free software; you can redistribute it and/or modify it under the
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# terms of the GNU Lesser General Public License as published by the Free
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# Software Foundation; either version 2.1 of the License, or (at your option)
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# any later version.
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#
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# 'ssh' is distrubuted in the hope that it will be useful, but WITHOUT ANY
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# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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# details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with 'ssh'; if not, write to the Free Software Foundation, Inc.,
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# 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA.
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"""
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Abstraction of a one-way pipe where the read end can be used in select().
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Normally this is trivial, but Windows makes it nearly impossible.
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The pipe acts like an Event, which can be set or cleared. When set, the pipe
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will trigger as readable in select().
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"""
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import sys
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import os
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import socket
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def make_pipe ():
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if sys.platform[:3] != 'win':
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p = PosixPipe()
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else:
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p = WindowsPipe()
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return p
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class PosixPipe (object):
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def __init__ (self):
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self._rfd, self._wfd = os.pipe()
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self._set = False
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self._forever = False
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self._closed = False
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def close (self):
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os.close(self._rfd)
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os.close(self._wfd)
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# used for unit tests:
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self._closed = True
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def fileno (self):
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return self._rfd
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def clear (self):
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if not self._set or self._forever:
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return
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os.read(self._rfd, 1)
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self._set = False
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def set (self):
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if self._set or self._closed:
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return
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self._set = True
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os.write(self._wfd, '*')
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def set_forever (self):
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self._forever = True
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self.set()
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class WindowsPipe (object):
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"""
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On Windows, only an OS-level "WinSock" may be used in select(), but reads
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and writes must be to the actual socket object.
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"""
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def __init__ (self):
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serv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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serv.bind(('127.0.0.1', 0))
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serv.listen(1)
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# need to save sockets in _rsock/_wsock so they don't get closed
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self._rsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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self._rsock.connect(('127.0.0.1', serv.getsockname()[1]))
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self._wsock, addr = serv.accept()
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serv.close()
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self._set = False
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self._forever = False
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self._closed = False
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def close (self):
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self._rsock.close()
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self._wsock.close()
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# used for unit tests:
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self._closed = True
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def fileno (self):
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return self._rsock.fileno()
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def clear (self):
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if not self._set or self._forever:
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return
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self._rsock.recv(1)
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self._set = False
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def set (self):
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if self._set or self._closed:
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return
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self._set = True
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self._wsock.send('*')
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def set_forever (self):
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self._forever = True
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self.set()
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class OrPipe (object):
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def __init__(self, pipe):
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self._set = False
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self._partner = None
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self._pipe = pipe
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def set(self):
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self._set = True
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if not self._partner._set:
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self._pipe.set()
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def clear(self):
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self._set = False
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if not self._partner._set:
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self._pipe.clear()
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def make_or_pipe(pipe):
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"""
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wraps a pipe into two pipe-like objects which are "or"d together to
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affect the real pipe. if either returned pipe is set, the wrapped pipe
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is set. when both are cleared, the wrapped pipe is cleared.
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"""
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p1 = OrPipe(pipe)
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p2 = OrPipe(pipe)
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p1._partner = p2
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p2._partner = p1
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return p1, p2
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