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Issue #27136: Fix DNS static resolution; don't use it in getaddrinfo

Browse source 
Patch by A. Jesse Jiryu Davis
This commit is contained in:
Yury Selivanov 2016-06-08 12:33:31 -04:00
parent 7d7a11b5d7
commit f1c6fa9866
6 changed files with 116 additions and 163 deletions
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116
Lib/asyncio/base_events.py
View file

@ -16,10 +16,8 @@ to modify the meaning of the API call itself.
import collections
import concurrent.futures
import functools
import heapq
import inspect
import ipaddress
import itertools
import logging
import os
@ -86,12 +84,14 @@ if hasattr(socket, 'SOCK_CLOEXEC'):
_SOCKET_TYPE_MASK |= socket.SOCK_CLOEXEC
@functools.lru_cache(maxsize=1024, typed=True)
def _ipaddr_info(host, port, family, type, proto):
# Try to skip getaddrinfo if "host" is already an IP. Since getaddrinfo
# blocks on an exclusive lock on some platforms, users might handle name
# resolution in their own code and pass in resolved IPs.
if proto not in {0, socket.IPPROTO_TCP, socket.IPPROTO_UDP} or host is None:
# Try to skip getaddrinfo if "host" is already an IP. Users might have
# handled name resolution in their own code and pass in resolved IPs.
if not hasattr(socket, 'inet_pton'):
return
if proto not in {0, socket.IPPROTO_TCP, socket.IPPROTO_UDP} or \
host is None:
return None
type &= ~_SOCKET_TYPE_MASK
@ -123,59 +123,42 @@ def _ipaddr_info(host, port, family, type, proto):
# Might be a service name like "http".
port = socket.getservbyname(port)
if hasattr(socket, 'inet_pton'):
if family == socket.AF_UNSPEC:
afs = [socket.AF_INET, socket.AF_INET6]
else:
afs = [family]
if family == socket.AF_UNSPEC:
afs = [socket.AF_INET, socket.AF_INET6]
else:
afs = [family]
for af in afs:
# Linux's inet_pton doesn't accept an IPv6 zone index after host,
# like '::1%lo0', so strip it. If we happen to make an invalid
# address look valid, we fail later in sock.connect or sock.bind.
try:
if af == socket.AF_INET6:
socket.inet_pton(af, host.partition('%')[0])
else:
socket.inet_pton(af, host)
return af, type, proto, '', (host, port)
except OSError:
pass
# "host" is not an IP address.
if isinstance(host, bytes):
host = host.decode('idna')
if '%' in host:
# Linux's inet_pton doesn't accept an IPv6 zone index after host,
# like '::1%lo0'.
return None
# No inet_pton. (On Windows it's only available since Python 3.4.)
# Even though getaddrinfo with AI_NUMERICHOST would be non-blocking, it
# still requires a lock on some platforms, and waiting for that lock could
# block the event loop. Use ipaddress instead, it's just text parsing.
try:
addr = ipaddress.IPv4Address(host)
except ValueError:
for af in afs:
try:
addr = ipaddress.IPv6Address(host.partition('%')[0])
except ValueError:
return None
socket.inet_pton(af, host)
# The host has already been resolved.
return af, type, proto, '', (host, port)
except OSError:
pass
af = socket.AF_INET if addr.version == 4 else socket.AF_INET6
if family not in (socket.AF_UNSPEC, af):
# "host" is wrong IP version for "family".
return None
return af, type, proto, '', (host, port)
# "host" is not an IP address.
return None
def _check_resolved_address(sock, address):
# Ensure that the address is already resolved to avoid the trap of hanging
# the entire event loop when the address requires doing a DNS lookup.
if hasattr(socket, 'AF_UNIX') and sock.family == socket.AF_UNIX:
return
def _ensure_resolved(address, *, family=0, type=socket.SOCK_STREAM, proto=0,
flags=0, loop):
host, port = address[:2]
if _ipaddr_info(host, port, sock.family, sock.type, sock.proto) is None:
raise ValueError("address must be resolved (IP address),"
" got host %r" % host)
info = _ipaddr_info(host, port, family, type, proto)
if info is not None:
# "host" is already a resolved IP.
fut = loop.create_future()
fut.set_result([info])
return fut
else:
return loop.getaddrinfo(host, port, family=family, type=type,
proto=proto, flags=flags)
def _run_until_complete_cb(fut):
@ -602,12 +585,7 @@ class BaseEventLoop(events.AbstractEventLoop):
def getaddrinfo(self, host, port, *,
family=0, type=0, proto=0, flags=0):
info = _ipaddr_info(host, port, family, type, proto)
if info is not None:
fut = self.create_future()
fut.set_result([info])
return fut
elif self._debug:
if self._debug:
return self.run_in_executor(None, self._getaddrinfo_debug,
host, port, family, type, proto, flags)
else:
@ -656,14 +634,14 @@ class BaseEventLoop(events.AbstractEventLoop):
raise ValueError(
'host/port and sock can not be specified at the same time')
f1 = self.getaddrinfo(
host, port, family=family,
type=socket.SOCK_STREAM, proto=proto, flags=flags)
f1 = _ensure_resolved((host, port), family=family,
type=socket.SOCK_STREAM, proto=proto,
flags=flags, loop=self)
fs = [f1]
if local_addr is not None:
f2 = self.getaddrinfo(
*local_addr, family=family,
type=socket.SOCK_STREAM, proto=proto, flags=flags)
f2 = _ensure_resolved(local_addr, family=family,
type=socket.SOCK_STREAM, proto=proto,
flags=flags, loop=self)
fs.append(f2)
else:
f2 = None
@ -798,9 +776,9 @@ class BaseEventLoop(events.AbstractEventLoop):
assert isinstance(addr, tuple) and len(addr) == 2, (
'2-tuple is expected')
infos = yield from self.getaddrinfo(
*addr, family=family, type=socket.SOCK_DGRAM,
proto=proto, flags=flags)
infos = yield from _ensure_resolved(
addr, family=family, type=socket.SOCK_DGRAM,
proto=proto, flags=flags, loop=self)
if not infos:
raise OSError('getaddrinfo() returned empty list')
@ -888,9 +866,9 @@ class BaseEventLoop(events.AbstractEventLoop):
@coroutine
def _create_server_getaddrinfo(self, host, port, family, flags):
infos = yield from self.getaddrinfo(host, port, family=family,
infos = yield from _ensure_resolved((host, port), family=family,
type=socket.SOCK_STREAM,
flags=flags)
flags=flags, loop=self)
if not infos:
raise OSError('getaddrinfo({!r}) returned empty list'.format(host))
return infos

9
Lib/asyncio/proactor_events.py
View file

@ -440,14 +440,7 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
return self._proactor.send(sock, data)
def sock_connect(self, sock, address):
try:
base_events._check_resolved_address(sock, address)
except ValueError as err:
fut = self.create_future()
fut.set_exception(err)
return fut
else:
return self._proactor.connect(sock, address)
return self._proactor.connect(sock, address)
def sock_accept(self, sock):
return self._proactor.accept(sock)

24
Lib/asyncio/selector_events.py
View file

@ -385,24 +385,28 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
def sock_connect(self, sock, address):
"""Connect to a remote socket at address.
The address must be already resolved to avoid the trap of hanging the
entire event loop when the address requires doing a DNS lookup. For
example, it must be an IP address, not a hostname, for AF_INET and
AF_INET6 address families. Use getaddrinfo() to resolve the hostname
asynchronously.
This method is a coroutine.
"""
if self._debug and sock.gettimeout() != 0:
raise ValueError("the socket must be non-blocking")
fut = self.create_future()
if hasattr(socket, 'AF_UNIX') and sock.family == socket.AF_UNIX:
self._sock_connect(fut, sock, address)
else:
resolved = base_events._ensure_resolved(address, loop=self)
resolved.add_done_callback(
lambda resolved: self._on_resolved(fut, sock, resolved))
return fut
def _on_resolved(self, fut, sock, resolved):
try:
base_events._check_resolved_address(sock, address)
except ValueError as err:
fut.set_exception(err)
_, _, _, _, address = resolved.result()[0]
except Exception as exc:
fut.set_exception(exc)
else:
self._sock_connect(fut, sock, address)
return fut
def _sock_connect(self, fut, sock, address):
fd = sock.fileno()