core: add support for ares_search

It's like ares_query but it takes the "domain" and "search" directives
in resolv.conf into accout.

Closes: #67

docs/channel.rst

@@ -190,6 +190,16 @@
         .. note::
             TTL is not implemented for CNAME and NS), so it's set to -1.
 
+    .. py:method:: search(name, query_type, callback)
+
+        :param string name: Name to query.
+
+        :param int query_type: Type of query to perform.
+
+        :param callable callback: Callback to be called with the result of the query.
+
+        Tis function does the same as :py:meth:`query` but it will honor the ``domain`` and ``search`` directives in
+        ``resolv.conf``.
 
     .. py:method:: cancel()
 

src/pycares/__init__.py

@@ -290,6 +290,8 @@ def parse_result(query_type, abuf, alen):
 
 
 class Channel:
+    __qtypes__ = (_lib.T_A, _lib.T_AAAA, _lib.T_ANY, _lib.T_CNAME, _lib.T_MX, _lib.T_NAPTR, _lib.T_NS, _lib.T_PTR, _lib.T_SOA, _lib.T_SRV, _lib.T_TXT)
+
     def __init__(self,
                  flags = None,
                  timeout = None,
@@ -500,15 +502,21 @@ def gethostbyname(self, name, family, callback):
         _lib.ares_gethostbyname(self._channel[0], parse_name(name), family, _host_cb, userdata)
 
     def query(self, name, query_type, callback):
+        self._do_query(_lib.ares_query, name, query_type, callback)
+
+    def search(self, name, query_type, callback):
+        self._do_query(_lib.ares_search, name, query_type, callback)
+
+    def _do_query(self, func, name, query_type, callback):
         if not callable(callback):
-            raise TypeError("a callable is required")
+            raise TypeError('a callable is required')
 
-        if query_type not in (_lib.T_A, _lib.T_AAAA, _lib.T_ANY, _lib.T_CNAME, _lib.T_MX, _lib.T_NAPTR, _lib.T_NS, _lib.T_PTR, _lib.T_SOA, _lib.T_SRV, _lib.T_TXT):
-            raise ValueError("invalid query type specified")
+        if query_type not in self.__qtypes__:
+            raise ValueError('invalid query type specified')
 
         userdata = _ffi.new_handle((callback, query_type))
         _global_set.add(userdata)
-        _lib.ares_query(self._channel[0], parse_name(name), _lib.C_IN, query_type, _query_cb, userdata)
+        func(self._channel[0], parse_name(name), _lib.C_IN, query_type, _query_cb, userdata)
 
     def set_local_ip(self, ip):
         addr4 = _ffi.new("struct in_addr*")

tests/tests.py

@@ -482,6 +482,18 @@ def test_errorcode_dict(self):
             val = getattr(pycares.errno, err)
             self.assertEqual(pycares.errno.errorcode[val], err)
 
+    def test_search(self):
+        self.result, self.errorno = None, None
+        def cb(result, errorno):
+            self.result, self.errorno = result, errorno
+        self.channel = pycares.Channel(timeout=5.0, tries=1, domains=['google.com'])
+        self.channel.search('cloud', pycares.QUERY_TYPE_A, cb)
+        self.wait()
+        self.assertNoError(self.errorno)
+        for r in self.result:
+            self.assertEqual(type(r), pycares.ares_query_a_result)
+            self.assertNotEqual(r.host, None)
+
 
 if __name__ == '__main__':
     unittest.main(verbosity=2)