Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #79771 > unrolled thread

asyncio: setting file permissions of a Unix socket?

Back to article view | Back to comp.lang.python

Contents

  asyncio: setting file permissions of a Unix socket? Martin <martin@libtec.org> - 2014-10-25 15:42 +0300
    Re: asyncio: setting file permissions of a Unix socket? Michael Ströder <michael@stroeder.com> - 2014-10-27 11:19 +0100

#79771 — asyncio: setting file permissions of a Unix socket?

Hi! :)

I'm using the asyncio.Protocol interface to build a server which binds
to a unix socket file.  I want other system users to connect to the
unix socket, so to communicate with the server.

Where should I set the permissions of the file?

The problem is that the socket file is created when the programs
starts listening for the connections.  Because of this, I can't change
the file permission before a connection is made.  At the same time, a
connection can't happen because of the file permissions.

Currently, I workaround this with os.umask(0o000).  But I also want to
make other files later with default permissions.  So I have to revert
the umask, but where?  I can only do this in the client connection
code, which is out of place.

Bellow is what I've done.  Can you suggest a better way?  I wish to
avoid permission fixing code like os.umask() for every connection.
Maybe I shouldn't use asyncio.Protocol in the first place?

Thank you! :)

Example code:

#! /usr/bin/env python3

import os
import asyncio

class ExampleServer(asyncio.Protocol):
    def __init__(self):
        os.umask(0o002)    # This is my workaround.  Can I avoid this?
        # if not umask_restored: # An alternative workaround.
        #     os.umask(0o002)

    def connection_made(self, transport):
        self.transport = transport

    def data_received(self, data):
        print("Data: ", data)
        self.transport.write(b"OK, bye!\n")
        self.transport.close()


def main():
    socket_filepath = "/tmp/example-server.socket"
    loop = asyncio.get_event_loop()
    server_coroutine = loop.create_unix_server(ExampleServer, socket_filepath)
    server = loop.run_until_complete(server_coroutine)

    os.umask(0o000)             # This is my workaround.

    try:
        loop.run_forever()
    except KeyboardInterrupt:
        print("exit")
    finally:
        server.close()
        loop.close()
        os.remove(socket_filepath)


if __name__ == "__main__":
    main()

[toc] | [next] | [standalone]

#79774

Martin wrote:
> I'm using the asyncio.Protocol interface to build a server which binds
> to a unix socket file.  I want other system users to connect to the
> unix socket, so to communicate with the server.
> 
> Where should I set the permissions of the file?

You should start the demon with a strict umask and set the permissions after
the socket is created.

Deriving from SocketServer.UnixStreamServer I'm overriding the server_bind()
method:

class MyServer(SocketServer.UnixStreamServer):
[..]
  def server_bind(self):
    """Override server_bind to set socket options."""
    self.socket.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
    self.socket.settimeout(SOCKET_TIMEOUT)
    try:
      os.unlink(self.server_address)
    except OSError:
      if os.path.exists(self.server_address):
        raise
    SocketServer.UnixStreamServer.server_bind(self)
    os.chmod(self.server_address,int(SOCKET_PERMISSIONS,8))
    return # server_bind()

Ciao, Michael.

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.python

csiph-web