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internet.py
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internet.py
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r"""
Feature for testing if the Internet is available
"""
# ****************************************************************************
# Copyright (C) 2021 Matthias Koeppe
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
# https://www.gnu.org/licenses/
# ****************************************************************************
from . import Feature, FeatureTestResult
class Internet(Feature):
r"""
A :class:`~sage.features.Feature` describing if Internet is available.
Failure of connecting to the site "https://www.sagemath.org" within a second
is regarded as internet being not available.
EXAMPLES::
sage: from sage.features.internet import Internet
sage: Internet()
Feature('internet')
"""
def __init__(self):
r"""
TESTS::
sage: from sage.features.internet import Internet
sage: Internet() is Internet()
True
"""
Feature.__init__(self, 'internet')
def _is_present(self):
r"""
Test whether Internet is available.
EXAMPLES::
sage: from sage.features.internet import Internet
sage: Internet()._is_present() # random, optional - internet
FeatureTestResult('internet', True)
"""
import urllib.error
from urllib.request import Request, urlopen
from ssl import create_default_context as default_context
req = Request("https://www.sagemath.org", headers={"User-Agent": "sage-doctest"})
try:
urlopen(req, timeout=1, context=default_context())
return FeatureTestResult(self, True)
except (urllib.error.URLError, TimeoutError):
return FeatureTestResult(self, False)
def all_features():
return [Internet()]