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Python

# -*- coding: utf-8 -*-
# Copyright (c) 2019 gevent contributors. See LICENSE for details.
#
# Portions of this code taken from dnspython
# https://github.com/rthalley/dnspython
#
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2003-2017 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.
"""
Private support for parsing /etc/hosts.
"""
from __future__ import absolute_import, division, print_function
import sys
import os
import re
from gevent.resolver._addresses import is_ipv4_addr
from gevent.resolver._addresses import is_ipv6_addr
from gevent._compat import iteritems
class HostsFile(object):
"""
A class to read the contents of a hosts file (/etc/hosts).
"""
LINES_RE = re.compile(r"""
\s* # Leading space
([^\r\n#]+?) # The actual match, non-greedy so as not to include trailing space
\s* # Trailing space
(?:[#][^\r\n]+)? # Comments
(?:$|[\r\n]+) # EOF or newline
""", re.VERBOSE)
def __init__(self, fname=None):
self.v4 = {} # name -> ipv4
self.v6 = {} # name -> ipv6
self.aliases = {} # name -> canonical_name
self.reverse = {} # ip addr -> some name
if fname is None:
if os.name == 'posix':
fname = '/etc/hosts'
elif os.name == 'nt': # pragma: no cover
fname = os.path.expandvars(
r'%SystemRoot%\system32\drivers\etc\hosts')
self.fname = fname
assert self.fname
self._last_load = 0
def _readlines(self):
# Read the contents of the hosts file.
#
# Return list of lines, comment lines and empty lines are
# excluded. Note that this performs disk I/O so can be
# blocking.
with open(self.fname, 'rb') as fp:
fdata = fp.read()
# XXX: Using default decoding. Is that correct?
udata = fdata.decode(errors='ignore') if not isinstance(fdata, str) else fdata
return self.LINES_RE.findall(udata)
def load(self): # pylint:disable=too-many-locals
# Load hosts file
# This will (re)load the data from the hosts
# file if it has changed.
try:
load_time = os.stat(self.fname).st_mtime
needs_load = load_time > self._last_load
except (IOError, OSError):
from gevent import get_hub
get_hub().handle_error(self, *sys.exc_info())
needs_load = False
if not needs_load:
return
v4 = {}
v6 = {}
aliases = {}
reverse = {}
for line in self._readlines():
parts = line.split()
if len(parts) < 2:
continue
ip = parts.pop(0)
if is_ipv4_addr(ip):
ipmap = v4
elif is_ipv6_addr(ip):
if ip.startswith('fe80'):
# Do not use link-local addresses, OSX stores these here
continue
ipmap = v6
else:
continue
cname = parts.pop(0).lower()
ipmap[cname] = ip
for alias in parts:
alias = alias.lower()
ipmap[alias] = ip
aliases[alias] = cname
# XXX: This is wrong for ipv6
if ipmap is v4:
ptr = '.'.join(reversed(ip.split('.'))) + '.in-addr.arpa'
else:
ptr = ip + '.ip6.arpa.'
if ptr not in reverse:
reverse[ptr] = cname
self._last_load = load_time
self.v4 = v4
self.v6 = v6
self.aliases = aliases
self.reverse = reverse
def iter_all_host_addr_pairs(self):
self.load()
for name, addr in iteritems(self.v4):
yield name, addr
for name, addr in iteritems(self.v6):
yield name, addr