use only ipv4 dns server

CHANGES

@@ -1,3 +1,6 @@
+2.1.0 2014-08-10
+- Use only IPv4 DNS server
+
 2.1.0 2014-08-01
 - Does not ship config.json
 - Better error message

setup.py

@@ -6,7 +6,7 @@ with open('README.rst') as f:
 
 setup(
     name="shadowsocks",
-    version="3.0",
+    version="2.1.0",
     license='MIT',
     description="A fast tunnel proxy that help you get through firewalls",
     author='clowwindy',

shadowsocks/asyncdns.py

@@ -232,7 +232,7 @@ def is_ip(address):
     for family in (socket.AF_INET, socket.AF_INET6):
         try:
             socket.inet_pton(family, address)
-            return True
+            return family
         except (TypeError, ValueError, OSError, IOError):
             pass
     return False
@@ -289,7 +289,7 @@ class DNSResolver(object):
                             parts = line.split()
                             if len(parts) >= 2:
                                 server = parts[1]
-                                if is_ip(server):
+                                if is_ip(server) == socket.AF_INET:
                                     self._servers.append(server)
         except IOError:
             pass