354 lines
13 KiB
Python
354 lines
13 KiB
Python
|
# Copyright (c) 2011-2015 Denis Bilenko. See LICENSE for details.
|
||
|
|
"""
|
||
|
|
c-ares based hostname resolver.
|
||
|
|
"""
|
||
|
|
from __future__ import absolute_import, print_function, division
|
||
|
|
import os
|
||
|
|
import warnings
|
||
|
|
|
||
|
|
from _socket import gaierror
|
||
|
|
from _socket import herror
|
||
|
|
from _socket import error
|
||
|
|
from _socket import EAI_NONAME
|
||
|
|
|
||
|
|
from gevent._compat import text_type
|
||
|
|
from gevent._compat import integer_types
|
||
|
|
|
||
|
|
from gevent.hub import Waiter
|
||
|
|
from gevent.hub import get_hub
|
||
|
|
|
||
|
|
from gevent.socket import AF_UNSPEC
|
||
|
|
from gevent.socket import AF_INET
|
||
|
|
from gevent.socket import AF_INET6
|
||
|
|
from gevent.socket import SOCK_DGRAM
|
||
|
|
from gevent.socket import SOCK_STREAM
|
||
|
|
from gevent.socket import SOL_TCP
|
||
|
|
from gevent.socket import SOL_UDP
|
||
|
|
|
||
|
|
|
||
|
|
from gevent._config import config
|
||
|
|
from gevent._config import AresSettingMixin
|
||
|
|
|
||
|
|
from .cares import channel, InvalidIP # pylint:disable=import-error,no-name-in-module
|
||
|
|
from . import _lookup_port as lookup_port
|
||
|
|
from . import AbstractResolver
|
||
|
|
|
||
|
|
__all__ = ['Resolver']
|
||
|
|
|
||
|
|
|
||
|
|
class Resolver(AbstractResolver):
|
||
|
|
"""
|
||
|
|
Implementation of the resolver API using the `c-ares`_ library.
|
||
|
|
|
||
|
|
This implementation uses the c-ares library to handle name
|
||
|
|
resolution. c-ares is natively asynchronous at the socket level
|
||
|
|
and so integrates well into gevent's event loop.
|
||
|
|
|
||
|
|
In comparison to :class:`gevent.resolver_thread.Resolver` (which
|
||
|
|
delegates to the native system resolver), the implementation is
|
||
|
|
much more complex. In addition, there have been reports of it not
|
||
|
|
properly honoring certain system configurations (for example, the
|
||
|
|
order in which IPv4 and IPv6 results are returned may not match
|
||
|
|
the threaded resolver). However, because it does not use threads,
|
||
|
|
it may scale better for applications that make many lookups.
|
||
|
|
|
||
|
|
There are some known differences from the system resolver.
|
||
|
|
|
||
|
|
- ``gethostbyname_ex`` and ``gethostbyaddr`` may return
|
||
|
|
different for the ``aliaslist`` tuple member. (Sometimes the
|
||
|
|
same, sometimes in a different order, sometimes a different
|
||
|
|
alias altogether.)
|
||
|
|
|
||
|
|
- ``gethostbyname_ex`` may return the ``ipaddrlist`` in a
|
||
|
|
different order.
|
||
|
|
|
||
|
|
- ``getaddrinfo`` does not return ``SOCK_RAW`` results.
|
||
|
|
|
||
|
|
- ``getaddrinfo`` may return results in a different order.
|
||
|
|
|
||
|
|
- Handling of ``.local`` (mDNS) names may be different, even
|
||
|
|
if they are listed in the hosts file.
|
||
|
|
|
||
|
|
- c-ares will not resolve ``broadcasthost``, even if listed in
|
||
|
|
the hosts file prior to 2020-04-30.
|
||
|
|
|
||
|
|
- This implementation may raise ``gaierror(4)`` where the
|
||
|
|
system implementation would raise ``herror(1)`` or vice versa,
|
||
|
|
with different error numbers. However, after 2020-04-30, this should be
|
||
|
|
much reduced.
|
||
|
|
|
||
|
|
- The results for ``localhost`` may be different. In
|
||
|
|
particular, some system resolvers will return more results
|
||
|
|
from ``getaddrinfo`` than c-ares does, such as SOCK_DGRAM
|
||
|
|
results, and c-ares may report more ips on a multi-homed
|
||
|
|
host.
|
||
|
|
|
||
|
|
- The system implementation may return some names fully qualified, where
|
||
|
|
this implementation returns only the host name. This appears to be
|
||
|
|
the case only with entries found in ``/etc/hosts``.
|
||
|
|
|
||
|
|
- c-ares supports a limited set of flags for ``getnameinfo`` and
|
||
|
|
``getaddrinfo``; unknown flags are ignored. System-specific flags
|
||
|
|
such as ``AI_V4MAPPED_CFG`` are not supported.
|
||
|
|
|
||
|
|
- ``getaddrinfo`` may return canonical names even without the ``AI_CANONNAME``
|
||
|
|
being set.
|
||
|
|
|
||
|
|
.. caution::
|
||
|
|
|
||
|
|
This module is considered extremely experimental on PyPy, and
|
||
|
|
due to its implementation in cython, it may be slower. It may also lead to
|
||
|
|
interpreter crashes.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.5.0
|
||
|
|
This version of gevent typically embeds c-ares 1.15.0 or newer. In
|
||
|
|
that version of c-ares, domains ending in ``.onion`` `are never
|
||
|
|
resolved <https://github.com/c-ares/c-ares/issues/196>`_ or even
|
||
|
|
sent to the DNS server.
|
||
|
|
|
||
|
|
.. versionchanged:: 20.5.0
|
||
|
|
``getaddrinfo`` is now implemented using the native c-ares function
|
||
|
|
from c-ares 1.16 or newer.
|
||
|
|
|
||
|
|
.. versionchanged:: 20.5.0
|
||
|
|
Now ``herror`` and ``gaierror`` are raised more consistently with
|
||
|
|
the standard library resolver, and have more consistent errno values.
|
||
|
|
|
||
|
|
Handling of localhost and broadcast names is now more consistent.
|
||
|
|
|
||
|
|
.. versionchanged:: 22.10.1
|
||
|
|
Now has a ``__del__`` method that warns if the object is destroyed
|
||
|
|
without being properly closed.
|
||
|
|
|
||
|
|
.. _c-ares: http://c-ares.haxx.se
|
||
|
|
"""
|
||
|
|
|
||
|
|
cares_class = channel
|
||
|
|
|
||
|
|
def __init__(self, hub=None, use_environ=True, **kwargs):
|
||
|
|
AbstractResolver.__init__(self)
|
||
|
|
if hub is None:
|
||
|
|
hub = get_hub()
|
||
|
|
self.hub = hub
|
||
|
|
if use_environ:
|
||
|
|
for setting in config.settings.values():
|
||
|
|
if isinstance(setting, AresSettingMixin):
|
||
|
|
value = setting.get()
|
||
|
|
if value is not None:
|
||
|
|
kwargs.setdefault(setting.kwarg_name, value)
|
||
|
|
self.cares = self.cares_class(hub.loop, **kwargs)
|
||
|
|
self.pid = os.getpid()
|
||
|
|
self.params = kwargs
|
||
|
|
self.fork_watcher = hub.loop.fork(ref=False) # We shouldn't keep the loop alive
|
||
|
|
self.fork_watcher.start(self._on_fork)
|
||
|
|
|
||
|
|
def __repr__(self):
|
||
|
|
return '<gevent.resolver_ares.Resolver at 0x%x ares=%r>' % (id(self), self.cares)
|
||
|
|
|
||
|
|
def _on_fork(self):
|
||
|
|
# NOTE: See comment in gevent.hub.reinit.
|
||
|
|
pid = os.getpid()
|
||
|
|
if pid != self.pid:
|
||
|
|
self.hub.loop.run_callback(self.cares.destroy)
|
||
|
|
self.cares = self.cares_class(self.hub.loop, **self.params)
|
||
|
|
self.pid = pid
|
||
|
|
|
||
|
|
def close(self):
|
||
|
|
AbstractResolver.close(self)
|
||
|
|
if self.cares is not None:
|
||
|
|
self.hub.loop.run_callback(self.cares.destroy)
|
||
|
|
self.cares = None
|
||
|
|
self.fork_watcher.stop()
|
||
|
|
|
||
|
|
def __del__(self):
|
||
|
|
if self.cares is not None:
|
||
|
|
warnings.warn("cares Resolver destroyed while not closed",
|
||
|
|
ResourceWarning)
|
||
|
|
self.close()
|
||
|
|
|
||
|
|
def _gethostbyname_ex(self, hostname_bytes, family):
|
||
|
|
while True:
|
||
|
|
ares = self.cares
|
||
|
|
try:
|
||
|
|
waiter = Waiter(self.hub)
|
||
|
|
ares.gethostbyname(waiter, hostname_bytes, family)
|
||
|
|
result = waiter.get()
|
||
|
|
if not result[-1]:
|
||
|
|
raise herror(EAI_NONAME, self.EAI_NONAME_MSG)
|
||
|
|
return result
|
||
|
|
except herror as ex:
|
||
|
|
if ares is self.cares:
|
||
|
|
if ex.args[0] == 1:
|
||
|
|
# Somewhere along the line, the internal
|
||
|
|
# implementation of gethostbyname_ex changed to invoke
|
||
|
|
# getaddrinfo() as a first pass, much like we do for ``getnameinfo()``;
|
||
|
|
# this means it raises a different error for not-found hosts.
|
||
|
|
raise gaierror(EAI_NONAME, self.EAI_NONAME_MSG)
|
||
|
|
raise
|
||
|
|
# "self.cares is not ares" means channel was destroyed (because we were forked)
|
||
|
|
|
||
|
|
def _lookup_port(self, port, socktype):
|
||
|
|
return lookup_port(port, socktype)
|
||
|
|
|
||
|
|
def __getaddrinfo(
|
||
|
|
self, host, port,
|
||
|
|
family=0, socktype=0, proto=0, flags=0,
|
||
|
|
fill_in_type_proto=True
|
||
|
|
):
|
||
|
|
"""
|
||
|
|
Returns a list ``(family, socktype, proto, canonname, sockaddr)``
|
||
|
|
|
||
|
|
:raises gaierror: If no results are found.
|
||
|
|
"""
|
||
|
|
# pylint:disable=too-many-locals,too-many-branches
|
||
|
|
if isinstance(host, text_type):
|
||
|
|
host = host.encode('idna')
|
||
|
|
|
||
|
|
|
||
|
|
if isinstance(port, text_type):
|
||
|
|
port = port.encode('ascii')
|
||
|
|
elif isinstance(port, integer_types):
|
||
|
|
if port == 0:
|
||
|
|
port = None
|
||
|
|
else:
|
||
|
|
port = str(port).encode('ascii')
|
||
|
|
|
||
|
|
waiter = Waiter(self.hub)
|
||
|
|
self.cares.getaddrinfo(
|
||
|
|
waiter,
|
||
|
|
host,
|
||
|
|
port,
|
||
|
|
family,
|
||
|
|
socktype,
|
||
|
|
proto,
|
||
|
|
flags,
|
||
|
|
)
|
||
|
|
# Result is a list of:
|
||
|
|
# (family, socktype, proto, canonname, sockaddr)
|
||
|
|
# Where sockaddr depends on family; for INET it is
|
||
|
|
# (address, port)
|
||
|
|
# and INET6 is
|
||
|
|
# (address, port, flow info, scope id)
|
||
|
|
result = waiter.get()
|
||
|
|
|
||
|
|
if not result:
|
||
|
|
raise gaierror(EAI_NONAME, self.EAI_NONAME_MSG)
|
||
|
|
|
||
|
|
if fill_in_type_proto:
|
||
|
|
# c-ares 1.16 DOES NOT fill in socktype or proto in the results,
|
||
|
|
# ever. It's at least supposed to do that if they were given as
|
||
|
|
# hints, but it doesn't (https://github.com/c-ares/c-ares/issues/317)
|
||
|
|
# Sigh.
|
||
|
|
# The SOL_* constants are another (older?) name for IPPROTO_*
|
||
|
|
if socktype:
|
||
|
|
hard_type_proto = [
|
||
|
|
(socktype, SOL_TCP if socktype == SOCK_STREAM else SOL_UDP),
|
||
|
|
]
|
||
|
|
elif proto:
|
||
|
|
hard_type_proto = [
|
||
|
|
(SOCK_STREAM if proto == SOL_TCP else SOCK_DGRAM, proto),
|
||
|
|
]
|
||
|
|
else:
|
||
|
|
hard_type_proto = [
|
||
|
|
(SOCK_STREAM, SOL_TCP),
|
||
|
|
(SOCK_DGRAM, SOL_UDP),
|
||
|
|
]
|
||
|
|
|
||
|
|
# pylint:disable=not-an-iterable,unsubscriptable-object
|
||
|
|
result = [
|
||
|
|
(rfamily,
|
||
|
|
hard_type if not rtype else rtype,
|
||
|
|
hard_proto if not rproto else rproto,
|
||
|
|
rcanon,
|
||
|
|
raddr)
|
||
|
|
for rfamily, rtype, rproto, rcanon, raddr
|
||
|
|
in result
|
||
|
|
for hard_type, hard_proto
|
||
|
|
in hard_type_proto
|
||
|
|
]
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _getaddrinfo(self, host_bytes, port, family, socktype, proto, flags):
|
||
|
|
while True:
|
||
|
|
ares = self.cares
|
||
|
|
try:
|
||
|
|
return self.__getaddrinfo(host_bytes, port, family, socktype, proto, flags)
|
||
|
|
except gaierror:
|
||
|
|
if ares is self.cares:
|
||
|
|
raise
|
||
|
|
|
||
|
|
def __gethostbyaddr(self, ip_address):
|
||
|
|
waiter = Waiter(self.hub)
|
||
|
|
try:
|
||
|
|
self.cares.gethostbyaddr(waiter, ip_address)
|
||
|
|
return waiter.get()
|
||
|
|
except InvalidIP:
|
||
|
|
result = self._getaddrinfo(ip_address, None,
|
||
|
|
family=AF_UNSPEC, socktype=SOCK_DGRAM,
|
||
|
|
proto=0, flags=0)
|
||
|
|
if not result:
|
||
|
|
raise
|
||
|
|
# pylint:disable=unsubscriptable-object
|
||
|
|
_ip_address = result[0][-1][0]
|
||
|
|
if isinstance(_ip_address, text_type):
|
||
|
|
_ip_address = _ip_address.encode('ascii')
|
||
|
|
if _ip_address == ip_address:
|
||
|
|
raise
|
||
|
|
waiter.clear()
|
||
|
|
self.cares.gethostbyaddr(waiter, _ip_address)
|
||
|
|
return waiter.get()
|
||
|
|
|
||
|
|
def _gethostbyaddr(self, ip_address_bytes):
|
||
|
|
while True:
|
||
|
|
ares = self.cares
|
||
|
|
try:
|
||
|
|
return self.__gethostbyaddr(ip_address_bytes)
|
||
|
|
except herror:
|
||
|
|
if ares is self.cares:
|
||
|
|
raise
|
||
|
|
|
||
|
|
def __getnameinfo(self, hostname, port, sockaddr, flags):
|
||
|
|
result = self.__getaddrinfo(
|
||
|
|
hostname, port,
|
||
|
|
family=AF_UNSPEC, socktype=SOCK_DGRAM,
|
||
|
|
proto=0, flags=0,
|
||
|
|
fill_in_type_proto=False)
|
||
|
|
if len(result) != 1:
|
||
|
|
raise error('sockaddr resolved to multiple addresses')
|
||
|
|
|
||
|
|
family, _socktype, _proto, _name, address = result[0]
|
||
|
|
|
||
|
|
if family == AF_INET:
|
||
|
|
if len(sockaddr) != 2:
|
||
|
|
raise error("IPv4 sockaddr must be 2 tuple")
|
||
|
|
elif family == AF_INET6:
|
||
|
|
address = address[:2] + sockaddr[2:]
|
||
|
|
|
||
|
|
waiter = Waiter(self.hub)
|
||
|
|
self.cares.getnameinfo(waiter, address, flags)
|
||
|
|
node, service = waiter.get()
|
||
|
|
|
||
|
|
if service is None:
|
||
|
|
# ares docs: "If the query did not complete
|
||
|
|
# successfully, or one of the values was not
|
||
|
|
# requested, node or service will be NULL ". Python 2
|
||
|
|
# allows that for the service, but Python 3 raises
|
||
|
|
# an error. This is tested by test_socket in py 3.4
|
||
|
|
err = gaierror(EAI_NONAME, self.EAI_NONAME_MSG)
|
||
|
|
err.errno = EAI_NONAME
|
||
|
|
raise err
|
||
|
|
|
||
|
|
return node, service or '0'
|
||
|
|
|
||
|
|
def _getnameinfo(self, address_bytes, port, sockaddr, flags):
|
||
|
|
while True:
|
||
|
|
ares = self.cares
|
||
|
|
try:
|
||
|
|
return self.__getnameinfo(address_bytes, port, sockaddr, flags)
|
||
|
|
except gaierror:
|
||
|
|
if ares is self.cares:
|
||
|
|
raise
|
||
|
|
|
||
|
|
# # Things that need proper error handling
|
||
|
|
# gethostbyaddr = AbstractResolver.convert_gaierror_to_herror(AbstractResolver.gethostbyaddr)
|