149 lines
4.4 KiB
Python
149 lines
4.4 KiB
Python
# -*- test-case-name: twisted.names.test.test_hosts -*-
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# Copyright (c) Twisted Matrix Laboratories.
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# See LICENSE for details.
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"""
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hosts(5) support.
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"""
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from __future__ import division, absolute_import
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from twisted.python.compat import nativeString
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from twisted.names import dns
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from twisted.python import failure
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from twisted.python.filepath import FilePath
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from twisted.internet import defer
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from twisted.internet.abstract import isIPAddress
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from twisted.names import common
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def searchFileForAll(hostsFile, name):
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"""
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Search the given file, which is in hosts(5) standard format, for an address
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entry with a given name.
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@param hostsFile: The name of the hosts(5)-format file to search.
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@type hostsFile: L{FilePath}
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@param name: The name to search for.
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@type name: C{str}
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@return: C{None} if the name is not found in the file, otherwise a
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C{str} giving the address in the file associated with the name.
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"""
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results = []
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try:
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lines = hostsFile.getContent().splitlines()
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except:
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return results
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name = name.lower()
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for line in lines:
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idx = line.find(b'#')
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if idx != -1:
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line = line[:idx]
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if not line:
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continue
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parts = line.split()
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if name.lower() in [s.lower() for s in parts[1:]]:
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results.append(nativeString(parts[0]))
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return results
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def searchFileFor(file, name):
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"""
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Grep given file, which is in hosts(5) standard format, for an address
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entry with a given name.
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@param file: The name of the hosts(5)-format file to search.
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@param name: The name to search for.
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@type name: C{str}
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@return: C{None} if the name is not found in the file, otherwise a
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C{str} giving the address in the file associated with the name.
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"""
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addresses = searchFileForAll(FilePath(file), name)
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if addresses:
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return addresses[0]
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return None
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class Resolver(common.ResolverBase):
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"""
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A resolver that services hosts(5) format files.
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"""
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def __init__(self, file=b'/etc/hosts', ttl = 60 * 60):
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common.ResolverBase.__init__(self)
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self.file = file
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self.ttl = ttl
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def _aRecords(self, name):
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"""
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Return a tuple of L{dns.RRHeader} instances for all of the IPv4
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addresses in the hosts file.
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"""
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return tuple([
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dns.RRHeader(name, dns.A, dns.IN, self.ttl,
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dns.Record_A(addr, self.ttl))
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for addr
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in searchFileForAll(FilePath(self.file), name)
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if isIPAddress(addr)])
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def _aaaaRecords(self, name):
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"""
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Return a tuple of L{dns.RRHeader} instances for all of the IPv6
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addresses in the hosts file.
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"""
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return tuple([
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dns.RRHeader(name, dns.AAAA, dns.IN, self.ttl,
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dns.Record_AAAA(addr, self.ttl))
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for addr
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in searchFileForAll(FilePath(self.file), name)
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if not isIPAddress(addr)])
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def _respond(self, name, records):
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"""
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Generate a response for the given name containing the given result
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records, or a failure if there are no result records.
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@param name: The DNS name the response is for.
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@type name: C{str}
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@param records: A tuple of L{dns.RRHeader} instances giving the results
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that will go into the response.
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@return: A L{Deferred} which will fire with a three-tuple of result
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records, authority records, and additional records, or which will
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fail with L{dns.DomainError} if there are no result records.
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"""
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if records:
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return defer.succeed((records, (), ()))
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return defer.fail(failure.Failure(dns.DomainError(name)))
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def lookupAddress(self, name, timeout=None):
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"""
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Read any IPv4 addresses from C{self.file} and return them as L{Record_A}
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instances.
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"""
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return self._respond(name, self._aRecords(name))
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def lookupIPV6Address(self, name, timeout=None):
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"""
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Read any IPv6 addresses from C{self.file} and return them as
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L{Record_AAAA} instances.
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"""
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return self._respond(name, self._aaaaRecords(name))
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# Someday this should include IPv6 addresses too, but that will cause
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# problems if users of the API (mainly via getHostByName) aren't updated to
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# know about IPv6 first.
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lookupAllRecords = lookupAddress
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