From e2b6d2d0f791778630d17c754a8c82f1cea3bc67 Mon Sep 17 00:00:00 2001 From: SomberNight Date: Sun, 1 Jul 2018 23:53:55 +0200 Subject: [PATCH] socket.getaddrinfo on win32: do our own dns resolution (second attempt, now trying to handle internal failure within dnspython) --- lib/network.py | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/lib/network.py b/lib/network.py index c113dda7c..f2f2aab76 100644 --- a/lib/network.py +++ b/lib/network.py @@ -31,8 +31,12 @@ from collections import defaultdict import threading import socket import json +import sys +import dns +import dns.resolver import socks + from . import util from . import bitcoin from .bitcoin import COIN @@ -444,7 +448,30 @@ class Network(util.DaemonThread): socket.getaddrinfo = lambda *args: [(socket.AF_INET, socket.SOCK_STREAM, 6, '', (args[0], args[1]))] else: socket.socket = socket._socketobject - socket.getaddrinfo = socket._getaddrinfo + if sys.platform == 'win32': + # On Windows, socket.getaddrinfo takes a mutex, and might hold it for up to 10 seconds + # when dns-resolving. To speed it up drastically, we resolve dns ourselves, outside that lock. + # see #4421 + def fast_getaddrinfo(host, *args, **kwargs): + try: + if str(host) not in ('localhost', 'localhost.',): + answers = dns.resolver.query(host) + addr = str(answers[0]) + else: + addr = host + except dns.exception.DNSException: + # dns failed for some reason, e.g. dns.resolver.NXDOMAIN + # this is normal. Simply report back failure: + raise socket.gaierror(11001, 'getaddrinfo failed') + except BaseException as e: + # Possibly internal error in dnspython :( see #4483 + # Fall back to original socket.getaddrinfo to resolve dns. + self.print_error('dnspython failed to resolve dns with error:', e) + addr = host + return socket._getaddrinfo(addr, *args, **kwargs) + socket.getaddrinfo = fast_getaddrinfo + else: + socket.getaddrinfo = socket._getaddrinfo @with_interface_lock def start_network(self, protocol, proxy):