Code to get and use machine id during DnD

docs/dnd-protocol.rst

@@ -133,8 +133,8 @@ terminal emulator must then inform the OS that the drop is completed.
 Dropping from remote machines
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-In order to support dropping of files from remote machines or to remote
-machines, clients can first request the :rfc:`text/uri-list <2483>` MIME
+In order to support dropping of files from remote machines,
+clients can first request the :rfc:`text/uri-list <2483>` MIME
 type to get a list of dropped URIs. For every URI in the list, they can
 send the terminal emulator a data request of the form::
 

kitty/dnd.c

@@ -25,6 +25,28 @@ static const size_t PRESENT_DATA_CAP = 64 * 1024 * 1024;
 // It receives (window_id: int, data: bytes) and its return value is ignored.
 static PyObject *g_dnd_test_write_func = NULL;
 
+static const char*
+machine_id(void) {
+    static bool done = false;
+    static char ans[512] = {0};
+    if (!done) {
+        done = true;
+        RAII_PyObject(mname, PyUnicode_DecodeFSDefault("kitty.machine_id"));
+        if (mname) {
+            RAII_PyObject(module, PyImport_Import(mname));
+            if (module) {
+                RAII_PyObject(func, PyObject_GetAttrString(module, "machine_id"));
+                if (func) {
+                    RAII_PyObject(ret, PyObject_CallFunction(func, "s", "tty-dnd-protocol-machine-id"));
+                    if (ret) snprintf(ans, sizeof(ans), "%s", PyUnicode_AsUTF8(ret));
+                }
+            }
+        }
+        if (PyErr_Occurred()) PyErr_Print();
+    }
+    return ans;
+}
+
 void
 dnd_set_test_write_func(PyObject *func) {
     Py_XDECREF(g_dnd_test_write_func);

kitty/machine_id.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+# License: GPLv3 Copyright: 2026, Kovid Goyal <kovid at kovidgoyal.net>
+
+import hashlib
+import hmac
+from contextlib import suppress
+from functools import lru_cache
+
+from kitty.constants import is_macos
+
+
+@lru_cache(maxsize=8)
+def machine_id(salt: str = '') -> str:
+    mid = b''
+    if is_macos:
+        from kitty.fast_data_types import cocoa_get_machine_id
+        mid = cocoa_get_machine_id().rstrip().encode()
+    else:
+        with suppress(OSError), open('/etc/machine-id', 'rb') as f:
+            mid = f.read().rstrip()
+    if not salt:
+        return mid.decode()
+    hmac_obj = hmac.new(salt.encode(), mid, hashlib.sha256)
+    return hmac_obj.hexdigest()