pybridge: Improve beiboot error reporting for fatal login failures

After all SSH authentication attemps fail, e.g. entering the wrong
password three times, ferny throws an InteractionError. Merely exiting
cockpit-beiboot gets interpreted as "Internal error" which is unfriendly.

Ferny recognizes the most common errors, like DNS resolution and and
authentication failure. Use that API to convert them to proper cockpit
protocol error codes, so that they get presented and translated properly.

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
 
@@ -309,8 +308,21 @@ async def run(args) -> None:
         bridge.write_control(message)
         bridge.ssh_peer.thaw_endpoint()
     except ferny.InteractionError as exc:
-        sys.exit(str(exc))
+        error = ferny.ssh_errors.get_exception_for_ssh_stderr(str(exc))
+        logger.debug("ferny.InteractionError: %s, interpreted as: %r", exc, error)
+        if isinstance(error, ferny.SshAuthenticationError):
+            problem = 'authentication-failed'
+        elif isinstance(error, ferny.SshHostKeyError):
+            problem = 'unknown-hostkey'
+        elif isinstance(error, OSError):
+            # usually DNS/socket errors
+            problem = 'unknown-host'
+        else:
+            problem = 'internal-error'
+        bridge.write_control(command='init', problem=problem, message=str(error))
+        return
     except CockpitProblem as exc:
+        logger.debug("CockpitProblem: %s", exc)
         bridge.write_control(exc.attrs, command='init')
         return
 

test/verify/check-client

@@ -147,13 +147,11 @@ Command = /usr/bin/env python3 -m cockpit.beiboot
             b.wait_text("#conversation-prompt", "admin@10.111.113.2's password: ")
             b.set_val("#conversation-input", "wrong")
             b.click("#login-button")
-        b.wait_in_text("#login-fatal-message", "admin@10.111.113.2: Permission denied")
-        b.click("#login-again")
-        b.wait_text("#brand", "Connect to:")
-        # resets the host field
-        b.wait_val("#server-field", "")
+        b.wait_in_text("#login-error-message", "Authentication failed")
+        b.wait_val("#server-field", "10.111.113.2")
 
         # connect to most recent host
+        b.open("/")  # reset URL from /metrics and last remote =host
         b.click("#recent-hosts-list .host-line button.host-name")
         b.wait_text("#conversation-prompt", "admin@10.111.113.2's password: ")
         b.set_val("#conversation-input", "foobar")
@@ -208,17 +206,16 @@ Command = /usr/bin/env python3 -m cockpit.beiboot
         # unreachable host
         b.set_val("#server-field", "unknownhost")
         b.click("#login-button")
-        b.wait_in_text("#login-fatal-message", "Could not resolve hostname unknownhost")
-        b.click("#login-again")
-        b.wait_text("#brand", "Connect to:")
+        b.wait_in_text("#login-error-message", "Host is unknown")
+        b.wait_val("#server-field", "unknownhost")
         # does not appear in recent hosts
         b.wait_in_text("#recent-hosts-list", "10.111.113.2")
         self.assertNotIn("unknownhost", b.text("#recent-hosts-list"))
 
         # wrong port
         b.set_val("#server-field", "10.111.113.2:222")
         b.click("#login-button")
-        b.wait_in_text("#login-fatal-message", "connect to host 10.111.113.2 port 222: No route to host")
+        b.wait_in_text("#login-error-message", "Host is unknown")
 
         # unencrypted SSH key login
         self.m_client.execute("runuser -u admin -- ssh-keygen -t rsa -N '' -f ~admin/.ssh/id_rsa")