Per @egilewski's audit on this PR (#15544), the original fix was
correct but the file has refactored since: the four endpoint-local
empty-peer checks have been consolidated into _ws_client_is_allowed
and _ws_client_reason, but the helpers were left fail-open ('no peer
host known means allow' / 'no reason to block').
On a loopback-bound dashboard with auth disabled, an ASGI server
behind a misconfigured proxy or a unix-socket transport can deliver
ws.client == None or ws.client.host == ''. The helpers were treating
that as 'allowed', so the loopback-only peer gate could be bypassed
by anything that suppressed the client tuple in transit. All four
WebSocket endpoints (/api/pty, /api/ws, /api/pub, /api/events) route
through _ws_request_is_allowed -> _ws_client_is_allowed, so the gap
applied uniformly.
Fix:
* _ws_client_is_allowed: return False when client_host is empty
instead of True. Only reached on loopback bind with auth disabled
(auth_required=True and explicit non-loopback binds short-circuit
earlier), so the fail-closed behavior is scoped to the surface
that needs it.
* _ws_client_reason: return a 'missing_or_empty_peer bound=...'
block reason instead of None, so the dispatcher's existing
reason-based rejection path picks it up and the close gets logged
with a machine-parseable token for diagnosability.
Behavior unchanged for:
* gated mode (auth_required=True) — early-returns True before the
empty-peer check runs. The OAuth ticket is the auth at that point.
* explicit non-loopback bind (--host 0.0.0.0/::, or a specific LAN
address, always with --insecure) — early-returns True before the
empty-peer check runs. DNS-rebinding is still blocked by the
Host/Origin guard in _ws_host_origin_is_allowed.
* legitimate loopback peers (client_host == '127.0.0.1' / '::1') —
not affected by the empty-peer branch.
Regression tests added in tests/hermes_cli/test_dashboard_auth_ws_auth.py:
* test_empty_client_host_rejected_in_loopback_mode
* test_missing_client_object_rejected_in_loopback_mode
* test_empty_client_host_reason_is_block
Plus two regression guards to ensure the fix does not over-reach:
* test_empty_client_host_still_allowed_in_insecure_public_mode
* test_empty_client_host_still_allowed_in_gated_mode
All three new fail-closed tests fail without this patch (the helpers
return True / None for an empty peer) and pass with it. The 45
pre-existing tests in test_dashboard_auth_ws_auth.py continue to pass.
ed3d12a762