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'.')
@@ -175,7 +178,7 @@ def parse_record(data, offset, question=False):
         )
         ip = parse_ip(record_type, data, record_rdlength, offset + nlen + 10)
         return nlen + 10 + record_rdlength, \
-            (name, ip, record_type, record_class, record_ttl)
+               (name, ip, record_type, record_class, record_ttl)
     else:
         record_type, record_class = struct.unpack(
             '!HH', data[offset + nlen:offset + nlen + 4]
@@ -209,7 +212,7 @@ def parse_response(data):
             if not header:
                 return None
             res_id, res_qr, res_tc, res_ra, res_rcode, res_qdcount, \
-                res_ancount, res_nscount, res_arcount = header
+            res_ancount, res_nscount, res_arcount = header
 
             qds = []
             ans = []
@@ -266,14 +269,18 @@ STATUS_IPV6 = 1
 
 
 class DNSResolver(object):
-
+    def __init__(self, black_hostname_list=None):
-    def __init__(self):
         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()
@@ -377,7 +384,7 @@ class DNSResolver(object):
             ip = None
             for answer in response.answers:
                 if answer[1] in (QTYPE_A, QTYPE_AAAA) and \
-                        answer[2] == QCLASS_IN:
+                                answer[2] == QCLASS_IN:
                     ip = answer[0]
                     break
             if IPV6_CONNECTION_SUPPORT:
@@ -465,16 +472,18 @@ 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))
                 return
             if False:
                 addrs = socket.getaddrinfo(hostname, 0, 0,
-                                       socket.SOCK_DGRAM, socket.SOL_UDP)
+                                           socket.SOCK_DGRAM, socket.SOL_UDP)
                 if addrs:
                     af, socktype, proto, canonname, sa = addrs[0]
-                    logging.debug('DNS resolve %s %s' % (hostname, sa[0]) )
+                    logging.debug('DNS resolve %s %s' % (hostname, sa[0]))
                     self._cache[hostname] = sa[0]
                     callback((hostname, sa[0]), None)
                     return
@@ -524,10 +533,11 @@ def test():
             if counter == 9:
                 dns_resolver.close()
                 loop.stop()
+
         a_callback = callback
         return a_callback
 
-    assert(make_callback() != make_callback())
+    assert (make_callback() != make_callback())
 
     dns_resolver.resolve(b'google.com', make_callback())
     dns_resolver.resolve('google.com', make_callback())
@@ -552,4 +562,3 @@ def test():
 
 if __name__ == '__main__':
     test()
-