77 lines
2.9 KiB
Python
77 lines
2.9 KiB
Python
from __future__ import absolute_import, division, print_function, with_statement
|
|
import pycares
|
|
import socket
|
|
|
|
from tornado import gen
|
|
from tornado.ioloop import IOLoop
|
|
from tornado.netutil import Resolver, is_valid_ip
|
|
|
|
|
|
class CaresResolver(Resolver):
|
|
"""Name resolver based on the c-ares library.
|
|
|
|
This is a non-blocking and non-threaded resolver. It may not produce
|
|
the same results as the system resolver, but can be used for non-blocking
|
|
resolution when threads cannot be used.
|
|
|
|
c-ares fails to resolve some names when ``family`` is ``AF_UNSPEC``,
|
|
so it is only recommended for use in ``AF_INET`` (i.e. IPv4). This is
|
|
the default for ``tornado.simple_httpclient``, but other libraries
|
|
may default to ``AF_UNSPEC``.
|
|
"""
|
|
def initialize(self, io_loop=None):
|
|
self.io_loop = io_loop or IOLoop.current()
|
|
self.channel = pycares.Channel(sock_state_cb=self._sock_state_cb)
|
|
self.fds = {}
|
|
|
|
def _sock_state_cb(self, fd, readable, writable):
|
|
state = ((IOLoop.READ if readable else 0) |
|
|
(IOLoop.WRITE if writable else 0))
|
|
if not state:
|
|
self.io_loop.remove_handler(fd)
|
|
del self.fds[fd]
|
|
elif fd in self.fds:
|
|
self.io_loop.update_handler(fd, state)
|
|
self.fds[fd] = state
|
|
else:
|
|
self.io_loop.add_handler(fd, self._handle_events, state)
|
|
self.fds[fd] = state
|
|
|
|
def _handle_events(self, fd, events):
|
|
read_fd = pycares.ARES_SOCKET_BAD
|
|
write_fd = pycares.ARES_SOCKET_BAD
|
|
if events & IOLoop.READ:
|
|
read_fd = fd
|
|
if events & IOLoop.WRITE:
|
|
write_fd = fd
|
|
self.channel.process_fd(read_fd, write_fd)
|
|
|
|
@gen.coroutine
|
|
def resolve(self, host, port, family=0):
|
|
if is_valid_ip(host):
|
|
addresses = [host]
|
|
else:
|
|
# gethostbyname doesn't take callback as a kwarg
|
|
self.channel.gethostbyname(host, family, (yield gen.Callback(1)))
|
|
callback_args = yield gen.Wait(1)
|
|
assert isinstance(callback_args, gen.Arguments)
|
|
assert not callback_args.kwargs
|
|
result, error = callback_args.args
|
|
if error:
|
|
raise Exception('C-Ares returned error %s: %s while resolving %s' %
|
|
(error, pycares.errno.strerror(error), host))
|
|
addresses = result.addresses
|
|
addrinfo = []
|
|
for address in addresses:
|
|
if '.' in address:
|
|
address_family = socket.AF_INET
|
|
elif ':' in address:
|
|
address_family = socket.AF_INET6
|
|
else:
|
|
address_family = socket.AF_UNSPEC
|
|
if family != socket.AF_UNSPEC and family != address_family:
|
|
raise Exception('Requested socket family %d but got %d' %
|
|
(family, address_family))
|
|
addrinfo.append((address_family, (address, port)))
|
|
raise gen.Return(addrinfo)
|