DNSResolver add black_hostname_list

TODO read black_hostname_list from config

shadowsocks/asyncdns.py

@@ -27,12 +27,12 @@ import logging
 if __name__ == '__main__':
     import sys
     import inspect
+
     file_path = os.path.dirname(os.path.realpath(inspect.getfile(inspect.currentframe())))
     sys.path.insert(0, os.path.join(file_path, '../'))
 
 from shadowsocks import common, lru_cache, eventloop, shell
 
-
 CACHE_SWEEP_INTERVAL = 30
 
 VALID_HOSTNAME = re.compile(br"(?!-)[A-Z\d_-]{1,63}(?<!-)$", re.IGNORECASE)
@@ -77,6 +77,7 @@ QTYPE_CNAME = 5
 QTYPE_NS = 2
 QCLASS_IN = 1
 
+
 def detect_ipv6_supprot():
     if 'has_ipv6' in dir(socket):
         try:
@@ -89,8 +90,10 @@ def detect_ipv6_supprot():
     print('IPv6 not support')
     return False
 
+
 IPV6_CONNECTION_SUPPORT = detect_ipv6_supprot()
 
+
 def build_address(address):
     address = address.strip(b'.')
     labels = address.split(b'.')
@@ -266,14 +269,18 @@ STATUS_IPV6 = 1
 
 
 class DNSResolver(object):
-
-    def __init__(self):
+    def __init__(self, black_hostname_list=None):
         self._loop = None
         self._hosts = {}
         self._hostname_status = {}
         self._hostname_to_cb = {}
         self._cb_to_hostname = {}
         self._cache = lru_cache.LRUCache(timeout=300)
+        # TODO read black_hostname_list from config
+        if type(black_hostname_list) != list:
+            self._black_hostname_list = []
+        else:
+            self._black_hostname_list = black_hostname_list
         self._sock = None
         self._servers = None
         self._parse_resolv()
@@ -465,6 +472,8 @@ class DNSResolver(object):
             logging.debug('hit cache: %s', hostname)
             ip = self._cache[hostname]
             callback((hostname, ip), None)
+        elif hostname in self._black_hostname_list:
+            callback(None, Exception('hostname <%s> in the black hostname list' % hostname))
         else:
             if not is_valid_hostname(hostname):
                 callback(None, Exception('invalid hostname: %s' % hostname))
@@ -524,6 +533,7 @@ def test():
             if counter == 9:
                 dns_resolver.close()
                 loop.stop()
+
         a_callback = callback
         return a_callback
 
@@ -552,4 +562,3 @@ def test():
 
 if __name__ == '__main__':
     test()
-