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# Copyright 2002 by Jeffrey Chang. All rights reserved.
# This code is part of the Biopython distribution and governed by its
# license. Please see the LICENSE file that should have been included
# as part of this package.
# This module attempts to detect whether the internet is available.
# To use it, import requires_internet into your Python code, and call
# requires_internet.check(). If the internet is available, then the
# import statement succeeds. If it is not, then the statement will
# result in a MissingExternalDependencyError exception.
"""Common code to check if the internet is available."""
from Bio import MissingExternalDependencyError
def check():
try:
check.available
except AttributeError:
# I'm going to check for internet availability
RELIABLE_DOMAIN = "biopython.org"
import socket
try:
socket.getaddrinfo(
RELIABLE_DOMAIN, 80, socket.AF_UNSPEC, socket.SOCK_STREAM
)
except socket.gaierror as x:
check.available = False
else:
check.available = True
if not check.available:
raise MissingExternalDependencyError("internet not available")
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