# Copyright (c) 2018 gevent contributors. See LICENSE for details.
# Portions of this code taken from the gogreen project:
# http://github.com/slideinc/gogreen
#
# Copyright (c) 2005-2010 Slide, Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following
# disclaimer in the documentation and/or other materials provided
# with the distribution.
# * Neither the name of the author nor the names of other
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# from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
# Portions of this code taken from the eventlet project:
# https://github.com/eventlet/eventlet/blob/master/eventlet/support/greendns.py
# Unless otherwise noted, the files in Eventlet are under the following MIT license:
# Copyright (c) 2005-2006, Bob Ippolito
# Copyright (c) 2007-2010, Linden Research, Inc.
# Copyright (c) 2008-2010, Eventlet Contributors (see AUTHORS)
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
from __future__ import absolute_import, print_function, division
import sys
import time
from _socket import error
from _socket import gaierror
from _socket import herror
from _socket import NI_NUMERICSERV
from _socket import AF_INET
from _socket import AF_INET6
from _socket import AF_UNSPEC
from _socket import EAI_NONAME
from _socket import EAI_FAMILY
import socket
from gevent.resolver import AbstractResolver
from gevent.resolver._hostsfile import HostsFile
from gevent.builtins import __import__ as g_import
from gevent._compat import string_types
from gevent._compat import iteritems
from gevent._config import config
__all__ = [
'Resolver',
]
# Import the DNS packages to use the gevent modules,
# even if the system is not monkey-patched. If it *is* already
# patched, this imports a second copy under a different name,
# which is probably not strictly necessary, but matches
# what we've historically done, and allows configuring the resolvers
# differently.
def _patch_dns():
from gevent._patcher import import_patched as importer
# The dns package itself is empty but defines __all__
# we make sure to import all of those things now under the
# patch. Note this triggers two DeprecationWarnings,
# one of which we could avoid.
extras = {
'dns': ('rdata', 'resolver', 'rdtypes'),
'dns.rdtypes': ('IN', 'ANY', ),
'dns.rdtypes.IN': ('A', 'AAAA',),
'dns.rdtypes.ANY': ('SOA', 'PTR'),
}
def extra_all(mod_name):
return extras.get(mod_name, ())
def after_import_hook(dns): # pylint:disable=redefined-outer-name
# Runs while still in the original patching scope.
# The dns.rdata:get_rdata_class() function tries to
# dynamically import modules using __import__ and then walk
# through the attribute tree to find classes in `dns.rdtypes`.
# It is critical that this all matches up, otherwise we can
# get different exception classes that don't get caught.
# We could patch __import__ to do things at runtime, but it's
# easier to enumerate the world and populate the cache now
# before we then switch the names back.
rdata = dns.rdata
get_rdata_class = rdata.get_rdata_class
try:
rdclass_values = list(dns.rdataclass.RdataClass)
except AttributeError:
# dnspython < 2.0
rdclass_values = dns.rdataclass._by_value
try:
rdtype_values = list(dns.rdatatype.RdataType)
except AttributeError:
# dnspython < 2.0
rdtype_values = dns.rdatatype._by_value
for rdclass in rdclass_values:
for rdtype in rdtype_values:
get_rdata_class(rdclass, rdtype)
patcher = importer('dns', extra_all, after_import_hook)
top = patcher.module
# Now disable the dynamic imports
def _no_dynamic_imports(name):
raise ValueError(name)
top.rdata.__import__ = _no_dynamic_imports
return top
dns = _patch_dns()
resolver = dns.resolver
dTimeout = dns.resolver.Timeout
# This is a wrapper for dns.resolver._getaddrinfo with two crucial changes.
# First, it backports https://github.com/rthalley/dnspython/issues/316
# from version 2.0. This can be dropped when we support only dnspython 2
# (which means only Python 3.)
# Second, it adds calls to sys.exc_clear() to avoid failing tests in
# test__refcount.py (timeouts) on Python 2. (Actually, this isn't
# strictly necessary, it was necessary to increase the timeouts in
# that function because dnspython is doing some parsing/regex/host
# lookups that are not super fast. But it does have a habit of leaving
# exceptions around which can complicate our memleak checks.)
def _getaddrinfo(host=None, service=None, family=AF_UNSPEC, socktype=0,
proto=0, flags=0,
_orig_gai=resolver._getaddrinfo,
_exc_clear=getattr(sys, 'exc_clear', lambda: None)):
if flags & (socket.AI_ADDRCONFIG | socket.AI_V4MAPPED) != 0:
# Not implemented. We raise a gaierror as opposed to a
# NotImplementedError as it helps callers handle errors more
# appropriately. [Issue #316]
raise socket.gaierror(socket.EAI_SYSTEM)
res = _orig_gai(host, service, family, socktype, proto, flags)
_exc_clear()
return res
resolver._getaddrinfo = _getaddrinfo
HOSTS_TTL = 300.0
class _HostsAnswer(dns.resolver.Answer):
# Answer class for HostsResolver object
def __init__(self, qname, rdtype, rdclass, rrset, raise_on_no_answer=True):
self.response = None
self.qname = qname
self.rdtype = rdtype
self.rdclass = rdclass
self.canonical_name = qname
if not rrset and raise_on_no_answer:
raise dns.resolver.NoAnswer()
self.rrset = rrset
self.expiration = (time.time() +
rrset.ttl if hasattr(rrset, 'ttl') else 0)
class _HostsResolver(object):
"""
Class to parse the hosts file
"""
def __init__(self, fname=None, interval=HOSTS_TTL):
self.hosts_file = HostsFile(fname)
self.interval = interval
self._last_load = 0
def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
tcp=False, source=None, raise_on_no_answer=True): # pylint:disable=unused-argument
# Query the hosts file
#
# The known rdtypes are dns.rdatatype.A, dns.rdatatype.AAAA and
# dns.rdatatype.CNAME.
# The ``rdclass`` parameter must be dns.rdataclass.IN while the
# ``tcp`` and ``source`` parameters are ignored.
# Return a HostAnswer instance or raise a dns.resolver.NoAnswer
# exception.
now = time.time()
hosts_file = self.hosts_file
if self._last_load + self.interval < now:
self._last_load = now
hosts_file.load()
rdclass = dns.rdataclass.IN # Always
if isinstance(qname, string_types):
name = qname
qname = dns.name.from_text(qname)
else:
name = str(qname)
name = name.lower()
rrset = dns.rrset.RRset(qname, rdclass, rdtype)
rrset.ttl = self._last_load + self.interval - now
if rdtype == dns.rdatatype.A:
mapping = hosts_file.v4
kind = dns.rdtypes.IN.A.A
elif rdtype == dns.rdatatype.AAAA:
mapping = hosts_file.v6
kind = dns.rdtypes.IN.AAAA.AAAA
elif rdtype == dns.rdatatype.CNAME:
mapping = hosts_file.aliases
kind = lambda c, t, addr: dns.rdtypes.ANY.CNAME.CNAME(c, t, dns.name.from_text(addr))
elif rdtype == dns.rdatatype.PTR:
mapping = hosts_file.reverse
kind = lambda c, t, addr: dns.rdtypes.ANY.PTR.PTR(c, t, dns.name.from_text(addr))
addr = mapping.get(name)
if not addr and qname.is_absolute():
addr = mapping.get(name[:-1])
if addr:
rrset.add(kind(rdclass, rdtype, addr))
return _HostsAnswer(qname, rdtype, rdclass, rrset, raise_on_no_answer)
def getaliases(self, hostname):
# Return a list of all the aliases of a given cname
# Due to the way store aliases this is a bit inefficient, this
# clearly was an afterthought. But this is only used by
# gethostbyname_ex so it's probably fine.
aliases = self.hosts_file.aliases
result = []
if hostname in aliases:
cannon = aliases[hostname]
else:
cannon = hostname
result.append(cannon)
for alias, cname in iteritems(aliases):
if cannon == cname:
result.append(alias)
result.remove(hostname)
return result
class _DualResolver(object):
def __init__(self):
self.hosts_resolver = _HostsResolver()
self.network_resolver = resolver.get_default_resolver()
self.network_resolver.cache = resolver.LRUCache()
def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
tcp=False, source=None, raise_on_no_answer=True,
_hosts_rdtypes=(dns.rdatatype.A, dns.rdatatype.AAAA, dns.rdatatype.PTR)):
# Query the resolver, using /etc/hosts
# Behavior:
# 1. if hosts is enabled and contains answer, return it now
# 2. query nameservers for qname
if qname is None:
qname = '0.0.0.0'
if not isinstance(qname, string_types):
if isinstance(qname, bytes):
qname = qname.decode("idna")
if isinstance(qname, string_types):
qname = dns.name.from_text(qname, None)
if isinstance(rdtype, string_types):
rdtype = dns.rdatatype.from_text(rdtype)
if rdclass == dns.rdataclass.IN and rdtype in _hosts_rdtypes:
try:
answer = self.hosts_resolver.query(qname, rdtype, raise_on_no_answer=False)
except Exception: # pylint: disable=broad-except
from gevent import get_hub
get_hub().handle_error(self, *sys.exc_info())
else:
if answer.rrset:
return answer
return self.network_resolver.query(qname, rdtype, rdclass,
tcp, source, raise_on_no_answer=raise_on_no_answer)
def _family_to_rdtype(family):
if family == socket.AF_INET:
rdtype = dns.rdatatype.A
elif family == socket.AF_INET6:
rdtype = dns.rdatatype.AAAA
else:
raise socket.gaierror(socket.EAI_FAMILY,
'Address family not supported')
return rdtype
class Resolver(AbstractResolver):
"""
An *experimental* resolver that uses `dnspython`_.
This is typically slower than the default threaded resolver
(unless there's a cache hit, in which case it can be much faster).
It is usually much faster than the c-ares resolver. It tends to
scale well as more concurrent resolutions are attempted.
Under Python 2, if the ``idna`` package is installed, this
resolver can resolve Unicode host names that the system resolver
cannot.
.. note::
This **does not** use dnspython's default resolver object, or share any
classes with ``import dns``. A separate copy of the objects is imported to
be able to function in a non monkey-patched process. The documentation for the resolver
object still applies.
The resolver that we use is available as the :attr:`resolver` attribute
of this object (typically ``gevent.get_hub().resolver.resolver``).
.. caution::
Many of the same caveats about DNS results apply here as are documented
for :class:`gevent.resolver.ares.Resolver`. In addition, the handling of
symbolic scope IDs in IPv6 addresses passed to ``getaddrinfo`` exhibits
some differences.
On PyPy, ``getnameinfo`` can produce results when CPython raises
``socket.error``, and gevent's DNSPython resolver also
raises ``socket.error``.
.. caution::
This resolver is experimental. It may be removed or modified in
the future. As always, feedback is welcome.
.. versionadded:: 1.3a2
.. versionchanged:: 20.5.0
The errors raised are now much more consistent with those
raised by the standard library resolvers.
Handling of localhost and broadcast names is now more consistent.
.. _dnspython: http://www.dnspython.org
"""
def __init__(self, hub=None): # pylint: disable=unused-argument
if resolver._resolver is None:
_resolver = resolver._resolver = _DualResolver()
if config.resolver_nameservers:
_resolver.network_resolver.nameservers[:] = config.resolver_nameservers
if config.resolver_timeout:
_resolver.network_resolver.lifetime = config.resolver_timeout
# Different hubs in different threads could be sharing the same
# resolver.
assert isinstance(resolver._resolver, _DualResolver)
self._resolver = resolver._resolver
@property
def resolver(self):
"""
The dnspython resolver object we use.
This object has several useful attributes that can be used to
adjust the behaviour of the DNS system:
* ``cache`` is a :class:`dns.resolver.LRUCache`. Its maximum size
can be configured by calling :meth:`resolver.cache.set_max_size`
* ``nameservers`` controls which nameservers to talk to
* ``lifetime`` configures a timeout for each individual query.
"""
return self._resolver.network_resolver
def close(self):
pass
def _getaliases(self, hostname, family):
if not isinstance(hostname, str):
if isinstance(hostname, bytes):
hostname = hostname.decode("idna")
aliases = self._resolver.hosts_resolver.getaliases(hostname)
net_resolver = self._resolver.network_resolver
rdtype = _family_to_rdtype(family)
while 1:
try:
ans = net_resolver.query(hostname, dns.rdatatype.CNAME, rdtype)
except (dns.resolver.NoAnswer, dns.resolver.NXDOMAIN, dns.resolver.NoNameservers):
break
except dTimeout:
break
except AttributeError as ex:
if hostname is None or isinstance(hostname, int):
raise TypeError(ex)
raise
else:
aliases.extend(str(rr.target) for rr in ans.rrset)
hostname = ans[0].target
return aliases
def _getaddrinfo(self, host_bytes, port, family, socktype, proto, flags):
# dnspython really wants the host to be in native format.
if not isinstance(host_bytes, str):
host_bytes = host_bytes.decode(self.HOSTNAME_ENCODING)
if host_bytes == 'ff02::1de:c0:face:8D':
# This is essentially a hack to make stdlib
# test_socket:GeneralModuleTests.test_getaddrinfo_ipv6_basic
# pass. They expect to get back a lowercase ``D``, but
# dnspython does not do that.
# ``test_getaddrinfo_ipv6_scopeid_symbolic`` also expect
# the scopeid to be dropped, but again, dnspython does not
# do that; we cant fix that here so we skip that test.
host_bytes = 'ff02::1de:c0:face:8d'
if family == AF_UNSPEC:
# This tends to raise in the case that a v6 address did not exist
# but a v4 does. So we break it into two parts.
# Note that if there is no ipv6 in the hosts file, but there *is*
# an ipv4, and there *is* an ipv6 in the nameservers, we will return
# both (from the first call). The system resolver on OS X only returns
# the results from the hosts file. doubleclick.com is one example.
# See also https://github.com/gevent/gevent/issues/1012
try:
return _getaddrinfo(host_bytes, port, family, socktype, proto, flags)
except gaierror:
try:
return _getaddrinfo(host_bytes, port, AF_INET6, socktype, proto, flags)
except gaierror:
return _getaddrinfo(host_bytes, port, AF_INET, socktype, proto, flags)
else:
try:
return _getaddrinfo(host_bytes, port, family, socktype, proto, flags)
except gaierror as ex:
if ex.args[0] == EAI_NONAME and family not in self._KNOWN_ADDR_FAMILIES:
# It's possible that we got sent an unsupported family. Check
# that.
ex.args = (EAI_FAMILY, self.EAI_FAMILY_MSG)
ex.errno = EAI_FAMILY
raise
def _getnameinfo(self, address_bytes, port, sockaddr, flags):
try:
return resolver._getnameinfo(sockaddr, flags)
except error:
if not flags:
# dnspython doesn't like getting ports it can't resolve.
# We have one test, test__socket_dns.py:Test_getnameinfo_geventorg.test_port_zero
# that does this. We conservatively fix it here; this could be expanded later.
return resolver._getnameinfo(sockaddr, NI_NUMERICSERV)
def _gethostbyaddr(self, ip_address_bytes):
try:
return resolver._gethostbyaddr(ip_address_bytes)
except gaierror as ex:
if ex.args[0] == EAI_NONAME:
# Note: The system doesn't *always* raise herror;
# sometimes the original gaierror propagates through.
# It's impossible to say ahead of time or just based
# on the name which it should be. The herror seems to
# be by far the most common, though.
raise herror(1, "Unknown host")
raise
# Things that need proper error handling
getnameinfo = AbstractResolver.fixup_gaierror(AbstractResolver.getnameinfo)
gethostbyaddr = AbstractResolver.fixup_gaierror(AbstractResolver.gethostbyaddr)
gethostbyname_ex = AbstractResolver.fixup_gaierror(AbstractResolver.gethostbyname_ex)
getaddrinfo = AbstractResolver.fixup_gaierror(AbstractResolver.getaddrinfo)