148 lines
4.7 KiB
Python
148 lines
4.7 KiB
Python
# Originally from astropy project (http://astropy.org), under BSD
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# 3-clause license.
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import contextlib
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import socket
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# save original socket method for restoration
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# These are global so that re-calling the turn_off_internet function doesn't
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# overwrite them again
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socket_original = socket.socket
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socket_create_connection = socket.create_connection
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socket_bind = socket.socket.bind
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socket_connect = socket.socket.connect
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INTERNET_OFF = False
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# urllib2 uses a global variable to cache its default "opener" for opening
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# connections for various protocols; we store it off here so we can restore to
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# the default after re-enabling internet use
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_orig_opener = None
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# ::1 is apparently another valid name for localhost?
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# it is returned by getaddrinfo when that function is given localhost
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def check_internet_off(original_function):
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"""
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Wraps ``original_function``, which in most cases is assumed
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to be a `socket.socket` method, to raise an `IOError` for any operations
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on non-local AF_INET sockets.
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"""
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def new_function(*args, **kwargs):
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if isinstance(args[0], socket.socket):
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if not args[0].family in (socket.AF_INET, socket.AF_INET6):
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# Should be fine in all but some very obscure cases
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# More to the point, we don't want to affect AF_UNIX
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# sockets.
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return original_function(*args, **kwargs)
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host = args[1][0]
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addr_arg = 1
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valid_hosts = ('localhost', '127.0.0.1', '::1')
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else:
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# The only other function this is used to wrap currently is
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# socket.create_connection, which should be passed a 2-tuple, but
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# we'll check just in case
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if not (isinstance(args[0], tuple) and len(args[0]) == 2):
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return original_function(*args, **kwargs)
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host = args[0][0]
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addr_arg = 0
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valid_hosts = ('localhost', '127.0.0.1')
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hostname = socket.gethostname()
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fqdn = socket.getfqdn()
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if host in (hostname, fqdn):
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host = 'localhost'
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new_addr = (host, args[addr_arg][1])
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args = args[:addr_arg] + (new_addr,) + args[addr_arg + 1:]
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if any(h in host for h in valid_hosts):
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return original_function(*args, **kwargs)
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else:
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raise IOError("An attempt was made to connect to the internet "
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"by a test that was not marked `remote_data`.")
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return new_function
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def turn_off_internet(verbose=False):
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"""
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Disable internet access via python by preventing connections from being
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created using the socket module. Presumably this could be worked around by
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using some other means of accessing the internet, but all default python
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modules (urllib, requests, etc.) use socket [citation needed].
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"""
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import urllib.request
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global INTERNET_OFF
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global _orig_opener
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if INTERNET_OFF:
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return
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INTERNET_OFF = True
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__tracebackhide__ = True
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if verbose:
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print("Internet access disabled")
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# Update urllib2 to force it not to use any proxies
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# Must use {} here (the default of None will kick off an automatic search
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# for proxies)
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_orig_opener = urllib.request.build_opener()
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no_proxy_handler = urllib.request.ProxyHandler({})
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opener = urllib.request.build_opener(no_proxy_handler)
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urllib.request.install_opener(opener)
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socket.create_connection = check_internet_off(socket_create_connection)
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socket.socket.bind = check_internet_off(socket_bind)
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socket.socket.connect = check_internet_off(socket_connect)
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return socket
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def turn_on_internet(verbose=False):
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"""
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Restore internet access. Not used, but kept in case it is needed.
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"""
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import urllib.request
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global INTERNET_OFF
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global _orig_opener
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if not INTERNET_OFF:
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return
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INTERNET_OFF = False
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if verbose:
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print("Internet access enabled")
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urllib.request.install_opener(_orig_opener)
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socket.create_connection = socket_create_connection
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socket.socket.bind = socket_bind
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socket.socket.connect = socket_connect
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return socket
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@contextlib.contextmanager
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def no_internet(verbose=False):
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"""Context manager to temporarily disable internet access (if not already
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disabled). If it was already disabled before entering the context manager
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(i.e. `turn_off_internet` was called previously) then this is a no-op and
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leaves internet access disabled until a manual call to `turn_on_internet`.
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"""
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already_disabled = INTERNET_OFF
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turn_off_internet(verbose=verbose)
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try:
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yield
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finally:
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if not already_disabled:
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turn_on_internet(verbose=verbose)
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