Start work on SSH askpass implementation

kitty/boss.py

@@ -701,6 +701,17 @@ def callback_(res: Dict[str, Any], x: int, boss: Boss) -> None:
             cmd += ['-c', c]
         self._run_kitten('ask', cmd, window=window, custom_callback=callback_, default_data={'response': ''})
 
+    def get_line(
+        self, msg: str,  # can contain newlines and ANSI formatting
+        callback: Callable[..., None],  # called with the answer or empty string when aborted
+        window: Optional[Window] = None,  # the window associated with the confirmation
+        is_password: bool = False
+    ) -> None:
+        def callback_(res: Dict[str, Any], x: int, boss: Boss) -> None:
+            callback(res.get('response') or '')
+        cmd = ['--type', 'password' if is_password else 'line', '--message', msg]
+        self._run_kitten('ask', cmd, window=window, custom_callback=callback_, default_data={'response': ''})
+
     def confirm_tab_close(self, tab: Tab) -> None:
         x = get_options().confirm_os_window_close
         num = tab.number_of_windows_with_running_programs if x < 0 else len(tab)

kitty/parser.c

@@ -1084,6 +1084,7 @@ dispatch_dcs(Screen *screen, PyObject DUMP_UNUSED *dump_callback) {
             } else IF_SIMPLE_PREFIX("kitty-print|", screen_handle_print)
             } else IF_SIMPLE_PREFIX("kitty-echo|", screen_handle_echo)
             } else IF_SIMPLE_PREFIX("kitty-ssh|", screen_handle_ssh)
+            } else IF_SIMPLE_PREFIX("kitty-askpass|", screen_handle_askpass)
 #undef IF_SIMPLE_PREFIX
             } else {
                 REPORT_ERROR("Unrecognized DCS @ code: 0x%x", screen->parser_buf[1]);

kitty/screen.c

@@ -2114,6 +2114,12 @@ screen_handle_ssh(Screen *self, PyObject *msg) {
     CALLBACK("handle_remote_ssh", "O", msg);
 }
 
+void
+screen_handle_askpass(Screen *self, PyObject *msg) {
+    CALLBACK("handle_remote_askpass", "O", msg);
+}
+
+
 void
 screen_request_capabilities(Screen *self, char c, PyObject *q) {
     static char buf[128];

kitty/screen.h

@@ -210,6 +210,7 @@ void screen_report_color_stack(Screen *);
 void screen_handle_print(Screen *, PyObject *cmd);
 void screen_handle_echo(Screen *, PyObject *cmd);
 void screen_handle_ssh(Screen *, PyObject *cmd);
+void screen_handle_askpass(Screen *, PyObject *cmd);
 void screen_designate_charset(Screen *, uint32_t which, uint32_t as);
 void screen_use_latin1(Screen *, bool);
 void set_title(Screen *self, PyObject*);

kitty/window.py

@@ -885,6 +885,35 @@ def handle_remote_ssh(self, msg: str) -> None:
         for line in get_ssh_data(msg, f'{os.getpid()}-{self.id}'):
             self.write_to_child(line)
 
+    def handle_remote_askpass(self, msg: str) -> None:
+        from .shm import SharedMemory
+        with SharedMemory(name=msg, readonly=True) as shm:
+            shm.seek(1)
+            data = json.loads(shm.read_data_with_size())
+
+        def callback(ans: Any) -> None:
+            data = json.dumps(ans)
+            with SharedMemory(name=msg) as shm:
+                shm.seek(1)
+                shm.write_data_with_size(data)
+                shm.flush()
+                shm.seek(0)
+                shm.write(b'\x01')
+
+        prompt: str = data['prompt']
+        if data['type'] == 'confirm':
+            get_boss().confirm(
+                prompt, callback, window=self, confirm_on_cancel=bool(data.get('confirm_on_cancel')),
+                confirm_on_accept=bool(data.get('confirm_on_accept')))
+        elif data['type'] == 'choose':
+            get_boss().choose(
+                prompt, callback, *data['choices'], window=self, default=data.get('default', ''))
+        elif data['type'] == 'get_line':
+            get_boss().get_line(
+                prompt, callback, window=self, is_password=bool(data.get('is_password')))
+        else:
+            log_error(f'Ignoring ask request with unknown type: {data["type"]}')
+
     def handle_remote_print(self, msg: str) -> None:
         text = process_remote_print(msg)
         print(text, end='', file=sys.stderr)

shell-integration/ssh/askpass.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env -S kitty +launch
+# License: GPLv3 Copyright: 2022, Kovid Goyal <kovid at kovidgoyal.net>
+
+import json
+import os
+import struct
+import sys
+
+from kitty.shm import SharedMemory
+
+msg = sys.argv[-1]
+prompt = os.environ.get('SSH_ASKPASS_PROMPT', '')
+is_confirm = prompt == 'confirm'
+ask_cmdline = ['-m', msg, '--type', 'yesno' if is_confirm else 'password']
+if is_confirm:
+    ask_cmdline += ['--default', 'y']
+data = json.dumps(ask_cmdline).encode('utf-8')
+sz = struct.pack('>I', len(data))
+with SharedMemory(size=len(data) + len(sz) + 1, unlink_on_exit=True, prefix=f'askpass-{os.getpid()}-') as shm, open(os.ctermid(), 'wb') as tty:
+    shm.write(b'\0')
+    shm.write(sz)
+    shm.write(data)
+    shm.flush()
+    print(f'\x1bP@kitty-ask|{shm.name}\x1b\\', flush=True)