resolver_ares: improve getaddrinfo

For string ports (e.g. "http") resolver_ares/getaddrinfo previously only
consulted getservbyname(port, "tcp") or getservbyname(port, "udp"), but never both.

It seems that checking of both work (and creating result based on that) makes for
better compatibility with stock getaddrinfo, at least on linux.

gevent/resolver_ares.py

@@ -61,18 +61,26 @@ class Resolver(object):
                 # "self.ares is not ares" means channel was destroyed (because we were forked)
 
     def _lookup_port(self, port, socktype):
+        socktypes = []
         if isinstance(port, string_types):
             try:
                 port = int(port)
             except ValueError:
                 try:
                     if socktype == 0:
+                        origport = port
                         try:
                             port = getservbyname(port, 'tcp')
-                            socktype = SOCK_STREAM
+                            socktypes.append(SOCK_STREAM)
                         except error:
                             port = getservbyname(port, 'udp')
-                            socktype = SOCK_DGRAM
+                            socktypes.append(SOCK_DGRAM)
+                        else:
+                            try:
+                                if port == getservbyname(origport, 'udp'):
+                                    socktypes.append(SOCK_DGRAM)
+                            except error:
+                                pass
                     elif socktype == SOCK_STREAM:
                         port = getservbyname(port, 'tcp')
                     elif socktype == SOCK_DGRAM:
@@ -94,7 +102,9 @@ class Resolver(object):
         else:
             raise error('Int or String expected')
         port = int(port % 65536)
-        return port, socktype
+        if not socktypes and socktype:
+            socktypes.append(socktype)
+        return port, socktypes
 
     def _getaddrinfo(self, host, port, family=0, socktype=0, proto=0, flags=0):
         if isinstance(host, unicode):
@@ -107,11 +117,12 @@ class Resolver(object):
             return getaddrinfo(host, port, family, socktype, proto, flags)
             # we also call _socket.getaddrinfo below if family is not one of AF_*
 
-        port, socktype = self._lookup_port(port, socktype)
+        origport = port
+        port, socktypes = self._lookup_port(port, socktype)
 
         socktype_proto = [(SOCK_STREAM, 6), (SOCK_DGRAM, 17), (SOCK_RAW, 0)]
-        if socktype:
-            socktype_proto = [(x, y) for (x, y) in socktype_proto if socktype == x]
+        if socktypes:
+            socktype_proto = [(x, y) for (x, y) in socktype_proto if x in socktypes]
         if proto:
             socktype_proto = [(x, y) for (x, y) in socktype_proto if proto == y]
 
@@ -129,7 +140,7 @@ class Resolver(object):
             ares.gethostbyname(values, host, AF_INET6)
         else:
             # most likely will raise the exception, let the original getaddrinfo do it
-            return getaddrinfo(host, port, family, socktype, proto, flags)
+            return getaddrinfo(host, origport, family, socktype, proto, flags)
 
         values = values.get()
         if len(values) == 2 and values[0] == values[1]: