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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2003-2007, 2009-2011 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
import enum
import inspect
import os
import socket
import dns.message
import dns.name
import dns.query
import dns.rdataclass
import dns.rdatatype
# Cache for is_internet_reachable()
_internet_reachable = None
_have_ipv4 = False
_have_ipv6 = False
def here(filename):
return os.path.join(os.path.dirname(__file__), filename)
def check_networking(addresses):
"""Can we do a DNS resolution via UDP and TCP to at least one of the addresses?"""
for address in addresses:
try:
q = dns.message.make_query(dns.name.root, dns.rdatatype.NS)
ok = False
# We try UDP a few times in case we get unlucky and a packet is lost.
for i in range(5):
# We don't check the answer other than make sure there is one.
try:
r = dns.query.udp(q, address, timeout=4)
ns = r.find_rrset(
r.answer, dns.name.root, dns.rdataclass.IN, dns.rdatatype.NS
)
ok = True
break
except Exception:
continue # UDP try loop
if not ok:
continue # addresses loop
try:
r = dns.query.tcp(q, address, timeout=4)
ns = r.find_rrset(
r.answer, dns.name.root, dns.rdataclass.IN, dns.rdatatype.NS
)
# UDP and TCP both work!
return True
except Exception:
continue
except Exception as e:
pass
return False
def is_internet_reachable():
"""Check if the Internet is reachable.
Setting the environment variable `NO_INTERNET` will let this
function always return False. The result is cached.
We check using the Google and Cloudflare public resolvers as they are highly
available and have well-known stable addresses.
"""
global _internet_reachable
if _internet_reachable is None:
if os.environ.get("NO_INTERNET"):
_internet_reachable = False
else:
global _have_ipv4
_have_ipv4 = check_networking(["8.8.8.8", "1.1.1.1"])
global _have_ipv6
_have_ipv6 = check_networking(
["2001:4860:4860::8888", "2606:4700:4700::1111"]
)
_internet_reachable = _have_ipv4 or _have_ipv6
return _internet_reachable
def have_ipv4():
if not is_internet_reachable():
return False
return _have_ipv4
def have_ipv6():
if not is_internet_reachable():
return False
return _have_ipv6
def enumerate_module(module, super_class):
"""Yield module attributes which are subclasses of given class"""
for attr_name in dir(module):
attr = getattr(module, attr_name)
if inspect.isclass(attr) and issubclass(attr, super_class):
yield attr
def check_enum_exports(module, eq_callback, only=None):
"""Make sure module exports all mnemonics from enums"""
for attr in enumerate_module(module, enum.Enum):
if only is not None and attr not in only:
# print('SKIP', attr)
continue
for flag, value in attr.__members__.items():
# print(module, flag, value)
eq_callback(getattr(module, flag), value)
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