Decode hostnames as ASCII/surrogateescape rather than UTF-8.

diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -737,6 +737,13 @@ PyThread_type_lock netdb_lock;
 #endif
 
 
+static PyObject *
+unicode_from_hostname(const char *buf)
+{
+    return PyUnicode_DecodeASCII(buf, strlen(buf), "surrogateescape");
+}
+
+
 /* Convert a string specifying a host name or one of a few symbolic
    names to a numeric IP address.  This usually calls gethostbyname()
    to do the work; the names "" and "<broadcast>" are special.
@@ -2963,7 +2970,7 @@ socket_gethostname(PyObject *self, PyObj
     if (res < 0)
         return set_error();
     buf[sizeof buf - 1] = '\0';
-    return PyUnicode_FromString(buf);
+    return unicode_from_hostname(buf);
 }
 
 PyDoc_STRVAR(gethostname_doc,
@@ -3045,7 +3052,7 @@ gethost_common(struct hostent *h, struct
     if (h->h_aliases) {
         for (pch = h->h_aliases; *pch != NULL; pch++) {
             int status;
-            tmp = PyUnicode_FromString(*pch);
+            tmp = unicode_from_hostname(*pch);
             if (tmp == NULL)
                 goto err;
 
@@ -3113,7 +3120,8 @@ gethost_common(struct hostent *h, struct
             goto err;
     }
 
-    rtn_tuple = Py_BuildValue("sOO", h->h_name, name_list, addr_list);
+    rtn_tuple = Py_BuildValue("NOO", unicode_from_hostname(h->h_name),
+                              name_list, addr_list);
 
  err:
     Py_XDECREF(name_list);
@@ -3879,9 +3887,9 @@ socket_getaddrinfo(PyObject *self, PyObj
             makesockaddr(-1, res->ai_addr, res->ai_addrlen, protocol);
         if (addr == NULL)
             goto err;
-        single = Py_BuildValue("iiisO", res->ai_family,
+        single = Py_BuildValue("iiiNO", res->ai_family,
             res->ai_socktype, res->ai_protocol,
-            res->ai_canonname ? res->ai_canonname : "",
+            unicode_from_hostname(res->ai_canonname ? res->ai_canonname : ""),
             addr);
         Py_DECREF(addr);
         if (single == NULL)
@@ -3980,7 +3988,7 @@ socket_getnameinfo(PyObject *self, PyObj
         set_gaierror(error);
         goto fail;
     }
-    ret = Py_BuildValue("ss", hbuf, pbuf);
+    ret = Py_BuildValue("Ns", unicode_from_hostname(hbuf), pbuf);
 
 fail:
     if (res)