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import asyncio
import socket
from .abc import AbstractResolver
__all__ = ('ThreadedResolver', 'AsyncResolver', 'DefaultResolver')
try:
import aiodns
# aiodns_default = hasattr(aiodns.DNSResolver, 'gethostbyname')
except ImportError: # pragma: no cover
aiodns = None
aiodns_default = False
class ThreadedResolver(AbstractResolver):
"""Use Executor for synchronous getaddrinfo() calls, which defaults to
concurrent.futures.ThreadPoolExecutor.
"""
def __init__(self, loop=None):
if loop is None:
loop = asyncio.get_event_loop()
self._loop = loop
async def resolve(self, host, port=0, family=socket.AF_INET):
infos = await self._loop.getaddrinfo(
host, port, type=socket.SOCK_STREAM, family=family)
hosts = []
for family, _, proto, _, address in infos:
hosts.append(
{'hostname': host,
'host': address[0], 'port': address[1],
'family': family, 'proto': proto,
'flags': socket.AI_NUMERICHOST})
return hosts
async def close(self):
pass
class AsyncResolver(AbstractResolver):
"""Use the `aiodns` package to make asynchronous DNS lookups"""
def __init__(self, loop=None, *args, **kwargs):
if loop is None:
loop = asyncio.get_event_loop()
if aiodns is None:
raise RuntimeError("Resolver requires aiodns library")
self._loop = loop
self._resolver = aiodns.DNSResolver(*args, loop=loop, **kwargs)
if not hasattr(self._resolver, 'gethostbyname'):
# aiodns 1.1 is not available, fallback to DNSResolver.query
self.resolve = self._resolve_with_query
async def resolve(self, host, port=0, family=socket.AF_INET):
try:
resp = await self._resolver.gethostbyname(host, family)
except aiodns.error.DNSError as exc:
msg = exc.args[1] if len(exc.args) >= 1 else "DNS lookup failed"
raise OSError(msg) from exc
hosts = []
for address in resp.addresses:
hosts.append(
{'hostname': host,
'host': address, 'port': port,
'family': family, 'proto': 0,
'flags': socket.AI_NUMERICHOST})
if not hosts:
raise OSError("DNS lookup failed")
return hosts
async def _resolve_with_query(self, host, port=0, family=socket.AF_INET):
if family == socket.AF_INET6:
qtype = 'AAAA'
else:
qtype = 'A'
try:
resp = await self._resolver.query(host, qtype)
except aiodns.error.DNSError as exc:
msg = exc.args[1] if len(exc.args) >= 1 else "DNS lookup failed"
raise OSError(msg) from exc
hosts = []
for rr in resp:
hosts.append(
{'hostname': host,
'host': rr.host, 'port': port,
'family': family, 'proto': 0,
'flags': socket.AI_NUMERICHOST})
if not hosts:
raise OSError("DNS lookup failed")
return hosts
async def close(self):
return self._resolver.cancel()
DefaultResolver = AsyncResolver if aiodns_default else ThreadedResolver