Accept ASCII/surrogateescape strings in getnameinfo().

diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -361,6 +361,10 @@ class GeneralModuleTests(unittest.TestCa
         self.tryHostnameArgs(lambda host: socket.getaddrinfo(host, None),
                              socket.gaierror)
 
+    def testGetnameinfoHostnames(self):
+        self.tryHostnameArgs(lambda host: socket.getnameinfo((host, 0), 0),
+                             socket.gaierror)
+
     def testSocketObjectHostnames(self):
         def f(host):
             s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -4012,6 +4012,7 @@ socket_getnameinfo(PyObject *self, PyObj
 {
     PyObject *sa = (PyObject *)NULL;
     int flags;
+    PyObject *hostobj;
     char *hostp;
     int port, flowinfo, scope_id;
     char hbuf[NI_MAXHOST], pbuf[NI_MAXSERV];
@@ -4027,9 +4028,10 @@ socket_getnameinfo(PyObject *self, PyObj
                         "getnameinfo() argument 1 must be a tuple");
         return NULL;
     }
-    if (!PyArg_ParseTuple(sa, "si|ii",
-                          &hostp, &port, &flowinfo, &scope_id))
+    if (!PyArg_ParseTuple(sa, "O&i|ii", hostname_converter,
+                          &hostobj, &port, &flowinfo, &scope_id))
         return NULL;
+    hostp = PyBytes_AS_STRING(hostobj);
     PyOS_snprintf(pbuf, sizeof(pbuf), "%d", port);
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = AF_UNSPEC;
@@ -4080,6 +4082,7 @@ socket_getnameinfo(PyObject *self, PyObj
 fail:
     if (res)
         freeaddrinfo(res);
+    Py_DECREF(hostobj);
     return ret;
 }