pybridge: Improve beiboot error reporting for fatal login failures

After all SSH authentication attemps fail, e.g. entering the wrong
password three times, ferny aborts with an InteractionError. Translate
that to a proper `authentication-failed` protocol error. Merely exiting
the problem gets interpreted as "Internal error" which is unfriendly.

src/cockpit/beiboot.py

@@ -22,7 +22,6 @@
 import logging
 import os
 import shlex
-import sys
 from pathlib import Path
 from typing import Dict, Iterable, Optional, Sequence
 
@@ -312,8 +311,11 @@ async def run(args) -> None:
         bridge.write_control(**message)
         bridge.ssh_peer.thaw_endpoint()
     except ferny.InteractionError as exc:
-        sys.exit(str(exc))
+        logger.debug("ferny.InteractionError: %s", exc)
+        bridge.write_control(command='init', problem='authentication-failed', message=str(exc))
+        return
     except CockpitProblem as exc:
+        logger.debug("CockpitProblem: %s", exc)
         bridge.write_control(command='init', problem=exc.problem, **exc.kwargs)
         return
 

test/verify/check-static-login

@@ -1014,8 +1014,11 @@ Command = {self.libexecdir}/cockpit-beiboot
             b.wait_text("#conversation-prompt", f"admin@{my_ip}'s password: ")
             b.set_val("#conversation-input", "wrong")
             b.click("#login-button")
-        # FIXME: better error message
-        b.wait_in_text("#login-fatal-message", "Internal error in login process")
+        b.wait_in_text("#login-error-message", "Authentication failed")
+        m.execute(f"! pgrep -af '[s]sh.*{my_ip}' >&2")
+        m.execute("! pgrep -af '[c]ockpit-beiboot' >&2")
+        # goes back to normal login form
+        b.wait_visible('#login-user-input')
 
         # colliding usernames; user names in "Connect to:" are *not* supported,
         # but pin down the behaviour