only use stable _uuid.generate_time_safe() to deduce MAC address

Author: picnixz

Lib/uuid.py

@@ -633,16 +633,18 @@ def _netstat_getnode():
 try:
     import _uuid
     _generate_time_safe = getattr(_uuid, "generate_time_safe", None)
+    _has_stable_extractable_node = _uuid.has_stable_extractable_node
     _UuidCreate = getattr(_uuid, "UuidCreate", None)
 except ImportError:
     _uuid = None
     _generate_time_safe = None
+    _has_stable_extractable_node = False
     _UuidCreate = None
 
 
 def _unix_getnode():
     """Get the hardware address on Unix using the _uuid extension module."""
-    if _generate_time_safe:
+    if _generate_time_safe and _has_stable_extractable_node:
         uuid_time, _ = _generate_time_safe()
         return UUID(bytes=uuid_time).node
 

Modules/_uuidmodule.c

@@ -78,23 +78,47 @@ py_UuidCreate(PyObject *Py_UNUSED(context),
     return NULL;
 }
 
+static int
+py_windows_has_stable_node(void)
+{
+    UUID uuid;
+    RCP_STATUS res;
+    Py_BEGIN_ALLOW_THREADS
+    res = UuidCreateSequential(&uuid);
+    Py_END_ALLOW_THREADS
+    return res == RPC_S_OK;
+}
 #endif /* MS_WINDOWS */
 
 
 static int
-uuid_exec(PyObject *module) {
+uuid_exec(PyObject *module)
+{
+#define ADD_INT(NAME, VALUE)                                        \
+    do {                                                            \
+        if (PyModule_AddIntConstant(module, (NAME), (VALUE)) < 0) { \
+           return -1;                                               \
+        }                                                           \
+    } while (0)
+
     assert(sizeof(uuid_t) == 16);
 #if defined(MS_WINDOWS)
-    int has_uuid_generate_time_safe = 0;
+    ADD_INT("has_uuid_generate_time_safe", 0);
 #elif defined(HAVE_UUID_GENERATE_TIME_SAFE)
-    int has_uuid_generate_time_safe = 1;
+    ADD_INT("has_uuid_generate_time_safe", 1);
 #else
-    int has_uuid_generate_time_safe = 0;
+    ADD_INT("has_uuid_generate_time_safe", 0);
 #endif
-    if (PyModule_AddIntConstant(module, "has_uuid_generate_time_safe",
-                                has_uuid_generate_time_safe) < 0) {
-        return -1;
-    }
+
+#if defined(MS_WINDOWS)
+    ADD_INT("has_stable_extractable_node", py_windows_has_stable_node());
+#elif defined(HAVE_UUID_GENERATE_TIME_SAFE_STABLE_MAC)
+    ADD_INT("has_stable_extractable_node", 1);
+#else
+    ADD_INT("has_stable_extractable_node", 0);
+#endif
+
+#undef ADD_INT
     return 0;
 }