Use ares_getaddrinfo instead of a hand-built method.

Does not yet handle canonical names, but this doesn't result in test failures.

docs/changes/1012.bugfix

+Use ``ares_getaddrinfo`` instead of a manual lookup.
+
+This requires c-ares 1.16.0.
+
+Note that this may change the results, in particular their order.
+
 As part of this, certain parts of the c-ares extension were adapted to
 use modern Cython idioms.
 

src/gevent/resolver/libcares.pxd

@@ -44,30 +44,31 @@ cdef extern from "ares.h":
     int ARES_SOCKET_BAD
 
     int ARES_SUCCESS
-    int ARES_ENODATA
-    int ARES_EFORMERR
-    int ARES_ESERVFAIL
-    int ARES_ENOTFOUND
-    int ARES_ENOTIMP
-    int ARES_EREFUSED
-    int ARES_EBADQUERY
-    int ARES_EBADNAME
+    int ARES_EADDRGETNETWORKPARAMS
     int ARES_EBADFAMILY
+    int ARES_EBADFLAGS
+    int ARES_EBADHINTS
+    int ARES_EBADNAME
+    int ARES_EBADQUERY
     int ARES_EBADRESP
+    int ARES_EBADSTR
+    int ARES_ECANCELLED
     int ARES_ECONNREFUSED
-    int ARES_ETIMEOUT
-    int ARES_EOF
+    int ARES_EDESTRUCTION
     int ARES_EFILE
+    int ARES_EFORMERR
+    int ARES_ELOADIPHLPAPI
+    int ARES_ENODATA
     int ARES_ENOMEM
-    int ARES_EDESTRUCTION
-    int ARES_EBADSTR
-    int ARES_EBADFLAGS
     int ARES_ENONAME
-    int ARES_EBADHINTS
+    int ARES_ENOTFOUND
+    int ARES_ENOTIMP
     int ARES_ENOTINITIALIZED
-    int ARES_ELOADIPHLPAPI
-    int ARES_EADDRGETNETWORKPARAMS
-    int ARES_ECANCELLED
+    int ARES_EOF
+    int ARES_EREFUSED
+    int ARES_ESERVFAIL
+    int ARES_ESERVICE
+    int ARES_ETIMEOUT
 
     int ARES_NI_NOFQDN
     int ARES_NI_NUMERICHOST

src/gevent/tests/test__socket_dns.py

@@ -47,10 +47,15 @@ def trace(message, *args, **kwargs):
         util.debug(message, *args, **kwargs)
 
 def _run(function, *args):
+    # Things that the stdlib should never raise and neither should we;
+    # these indicate bugs in our code and we want to raise them.
+    REAL_ERRORS = (AttributeError, ValueError, NameError)
     try:
         result = function(*args)
         assert not isinstance(result, BaseException), repr(result)
         return result
+    except REAL_ERRORS:
+        raise
     except Exception as ex:
         if TRACE:
             traceback.print_exc()
@@ -230,7 +235,7 @@ def add(klass, hostname, name=None,
 
 @skipWithoutExternalNetwork("Tries to resolve and compare hostnames/addrinfo")
 class TestCase(greentest.TestCase):
-
+    maxDiff = None
     __timeout__ = 30
     switch_expected = None
     verbose_dns = TRACE