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# -*- test-case-name: twisted.names.test -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Base functionality useful to various parts of Twisted Names.
"""
import socket
from zope.interface import implementer
from twisted.internet import defer, error, interfaces
from twisted.logger import Logger
from twisted.names import dns
from twisted.names.error import (
DNSFormatError,
DNSNameError,
DNSNotImplementedError,
DNSQueryRefusedError,
DNSServerError,
DNSUnknownError,
)
# Helpers for indexing the three-tuples that get thrown around by this code a
# lot.
_ANS, _AUTH, _ADD = range(3)
EMPTY_RESULT = (), (), ()
@implementer(interfaces.IResolver)
class ResolverBase:
"""
L{ResolverBase} is a base class for implementations of
L{interfaces.IResolver} which deals with a lot
of the boilerplate of implementing all of the lookup methods.
@cvar _errormap: A C{dict} mapping DNS protocol failure response codes
to exception classes which will be used to represent those failures.
"""
_log = Logger()
_errormap = {
dns.EFORMAT: DNSFormatError,
dns.ESERVER: DNSServerError,
dns.ENAME: DNSNameError,
dns.ENOTIMP: DNSNotImplementedError,
dns.EREFUSED: DNSQueryRefusedError,
}
typeToMethod = None
def __init__(self):
self.typeToMethod = {}
for k, v in typeToMethod.items():
self.typeToMethod[k] = getattr(self, v)
def exceptionForCode(self, responseCode):
"""
Convert a response code (one of the possible values of
L{dns.Message.rCode} to an exception instance representing it.
@since: 10.0
"""
return self._errormap.get(responseCode, DNSUnknownError)
def query(self, query, timeout=None):
try:
method = self.typeToMethod[query.type]
except KeyError:
self._log.debug(
"Query of unknown type {query.type} for {query.name.name!r}",
query=query,
)
return defer.maybeDeferred(
self._lookup, query.name.name, dns.IN, query.type, timeout
)
else:
return defer.maybeDeferred(method, query.name.name, timeout)
def _lookup(self, name, cls, type, timeout):
return defer.fail(NotImplementedError("ResolverBase._lookup"))
def lookupAddress(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.A, timeout)
def lookupIPV6Address(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.AAAA, timeout)
def lookupAddress6(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.A6, timeout)
def lookupMailExchange(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.MX, timeout)
def lookupNameservers(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.NS, timeout)
def lookupCanonicalName(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.CNAME, timeout)
def lookupMailBox(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.MB, timeout)
def lookupMailGroup(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.MG, timeout)
def lookupMailRename(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.MR, timeout)
def lookupPointer(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.PTR, timeout)
def lookupAuthority(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.SOA, timeout)
def lookupNull(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.NULL, timeout)
def lookupWellKnownServices(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.WKS, timeout)
def lookupService(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.SRV, timeout)
def lookupHostInfo(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.HINFO, timeout)
def lookupMailboxInfo(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.MINFO, timeout)
def lookupText(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.TXT, timeout)
def lookupSenderPolicy(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.SPF, timeout)
def lookupResponsibility(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.RP, timeout)
def lookupAFSDatabase(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.AFSDB, timeout)
def lookupZone(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.AXFR, timeout)
def lookupNamingAuthorityPointer(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.NAPTR, timeout)
def lookupAllRecords(self, name, timeout=None):
return self._lookup(dns.domainString(name), dns.IN, dns.ALL_RECORDS, timeout)
# IResolverSimple
def getHostByName(self, name, timeout=None, effort=10):
name = dns.domainString(name)
# XXX - respect timeout
# XXX - this should do A and AAAA lookups, not ANY (see RFC 8482).
# https://twistedmatrix.com/trac/ticket/9691
d = self.lookupAllRecords(name, timeout)
d.addCallback(self._cbRecords, name, effort)
return d
def _cbRecords(self, records, name, effort):
(ans, auth, add) = records
result = extractRecord(self, dns.Name(name), ans + auth + add, effort)
if not result:
raise error.DNSLookupError(name)
return result
def extractRecord(resolver, name, answers, level=10):
"""
Resolve a name to an IP address, following I{CNAME} records and I{NS}
referrals recursively.
This is an implementation detail of L{ResolverBase.getHostByName}.
@param resolver: The resolver to use for the next query (unless handling
an I{NS} referral).
@type resolver: L{IResolver}
@param name: The name being looked up.
@type name: L{dns.Name}
@param answers: All of the records returned by the previous query (answers,
authority, and additional concatenated).
@type answers: L{list} of L{dns.RRHeader}
@param level: Remaining recursion budget. This is decremented at each
recursion. The query returns L{None} when it reaches 0.
@type level: L{int}
@returns: The first IPv4 or IPv6 address (as a dotted quad or colon
quibbles), or L{None} when no result is found.
@rtype: native L{str} or L{None}
"""
if not level:
return None
# FIXME: twisted.python.compat monkeypatches this if missing, so this
# condition is always true. https://twistedmatrix.com/trac/ticket/9753
if hasattr(socket, "inet_ntop"):
for r in answers:
if r.name == name and r.type == dns.A6:
return socket.inet_ntop(socket.AF_INET6, r.payload.address)
for r in answers:
if r.name == name and r.type == dns.AAAA:
return socket.inet_ntop(socket.AF_INET6, r.payload.address)
for r in answers:
if r.name == name and r.type == dns.A:
return socket.inet_ntop(socket.AF_INET, r.payload.address)
for r in answers:
if r.name == name and r.type == dns.CNAME:
result = extractRecord(resolver, r.payload.name, answers, level - 1)
if not result:
return resolver.getHostByName(r.payload.name.name, effort=level - 1)
return result
# No answers, but maybe there's a hint at who we should be asking about
# this
for r in answers:
if r.type != dns.NS:
continue
from twisted.names import client
nsResolver = client.Resolver(
servers=[
(r.payload.name.name.decode("ascii"), dns.PORT),
]
)
def queryAgain(records):
(ans, auth, add) = records
return extractRecord(nsResolver, name, ans + auth + add, level - 1)
return nsResolver.lookupAddress(name.name).addCallback(queryAgain)
typeToMethod = {
dns.A: "lookupAddress",
dns.AAAA: "lookupIPV6Address",
dns.A6: "lookupAddress6",
dns.NS: "lookupNameservers",
dns.CNAME: "lookupCanonicalName",
dns.SOA: "lookupAuthority",
dns.MB: "lookupMailBox",
dns.MG: "lookupMailGroup",
dns.MR: "lookupMailRename",
dns.NULL: "lookupNull",
dns.WKS: "lookupWellKnownServices",
dns.PTR: "lookupPointer",
dns.HINFO: "lookupHostInfo",
dns.MINFO: "lookupMailboxInfo",
dns.MX: "lookupMailExchange",
dns.TXT: "lookupText",
dns.SPF: "lookupSenderPolicy",
dns.RP: "lookupResponsibility",
dns.AFSDB: "lookupAFSDatabase",
dns.SRV: "lookupService",
dns.NAPTR: "lookupNamingAuthorityPointer",
dns.AXFR: "lookupZone",
dns.ALL_RECORDS: "lookupAllRecords",
}