Jack Nagy
1a35cd59a1
A stateless-by-default DTLS ClientHello probe that classifies a host:port as DEAD/LIVE/COMPLETED/REJECTED in ~1 RTT off the server's first flight, sitting in front of the full handshake. Probe (smartthings_local/protocol/dtls_probe.py): - Stateless liveness mode (default): stops at HelloVerifyRequest and never sends the cookie'd second ClientHello, so by RFC 6347 §4.2.1 it leaves no association on the device — safe to run before a real connect. - Diagnostic mode (stateless=False): drives the handshake further to capture cipher/cert-chain/CertificateRequest or a fatal Alert, for OCF-PKI-wall characterization (#16). Kept out of hot reconnect paths. - Retransmit + retries: services OpenSSL's DTLS retransmit timer so a single dropped ClientHello no longer reads as a false DEAD. MQTT bridge (mqtt_demo): - Stateless pre-flight gate in session_once() rejects a silent/rebooting device or wrong port in ~3s (retries=1) instead of eating the 12s HANDSHAKE_TIMEOUT_S per reconnect. - OCF-band port autodiscovery when OCF_PORT is unset: races the band in parallel and returns on the first port to answer LIVE (~1 RTT, abandoning the dead-port probes), cached across reconnects; the stateless gate leaves no orphan, preserving the fixed-source-port §4.2.8 invariant. Validated on real hardware (dryer 49155 / oven 49154): parallel discovery resolves both ports in <1s, connect with no orphan cooldown, and a wrong pinned port rejected in ~3s. Tests: probe behaviour (retransmit recovery, stateless single-flight guard, silent-port flight budget, diagnostic continuation) and bridge port-resolution (pinned gate, parallel discovery early-exit, cache).
107 lines
4.1 KiB
Python
107 lines
4.1 KiB
Python
"""Port-resolution logic for the MQTT bridge: the stateless pre-flight
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gate and OCF-band autodiscovery in PushBridge. The DTLS probe is faked so
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these run without hardware — only the routing/gating/caching is exercised.
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"""
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import logging
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import time
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import types
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import pytest
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import mqtt_demo.bridge as bridge
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def _mk_bridge(ocf_port, default=49155, discovered=None):
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"""A PushBridge shell with only the attributes _resolve_port touches,
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bypassing the heavyweight __init__ (MQTT client, cert paths, …)."""
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b = bridge.PushBridge.__new__(bridge.PushBridge)
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b.app = types.SimpleNamespace(ip='10.0.0.9', ocf_port=ocf_port, index=0)
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b.descriptor = types.SimpleNamespace(default_observe_port=default)
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b._discovered_port = discovered
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b.log = logging.getLogger('test-bridge')
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return b
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def _fake_probe(live_ports):
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"""Return a probe() stand-in reporting is_dtls_server for live_ports."""
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def fake(ip, port, **kw):
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alive = port in live_ports
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return types.SimpleNamespace(
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port=port, is_dtls_server=alive,
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outcome='live' if alive else 'dead')
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return fake
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def test_pinned_live_port_is_gated_and_returned(monkeypatch):
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monkeypatch.setattr(bridge, 'probe', _fake_probe({49155}))
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b = _mk_bridge(ocf_port=49155)
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assert b._resolve_port() == 49155
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def test_pinned_dead_port_raises_for_backoff(monkeypatch):
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monkeypatch.setattr(bridge, 'probe', _fake_probe(set()))
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b = _mk_bridge(ocf_port=49155)
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with pytest.raises(ConnectionError):
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b._resolve_port()
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def test_autodiscovery_finds_and_caches_live_port(monkeypatch):
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# Only 49154 answers; it isn't the descriptor default, so discovery is
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# what finds it — and it must be cached for the next reconnect.
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monkeypatch.setattr(bridge, 'probe', _fake_probe({49154}))
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b = _mk_bridge(ocf_port=None, default=49155)
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assert b._resolve_port() == 49154
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assert b._discovered_port == 49154
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def test_autodiscovery_returns_a_live_port(monkeypatch):
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# Early-exit: the first candidate to answer LIVE wins. Real devices
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# expose exactly one DTLS port; if several answer, any live one is a
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# correct result.
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monkeypatch.setattr(bridge, 'probe', _fake_probe({49153, 49155}))
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b = _mk_bridge(ocf_port=None, default=49155)
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assert b._resolve_port() in {49153, 49155}
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def test_autodiscovery_early_exits_before_dead_ports_finish(monkeypatch):
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# The live port answers immediately; the dead ports "hang" on their
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# retry budget. Discovery must return at the live port's speed, not
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# block on the slow dead probes.
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def slow_probe(ip, port, **kw):
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if port == 49154:
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return types.SimpleNamespace(
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port=port, is_dtls_server=True, outcome='live')
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time.sleep(0.5) # a dead port burning its retry budget
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return types.SimpleNamespace(
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port=port, is_dtls_server=False, outcome='dead')
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monkeypatch.setattr(bridge, 'probe', slow_probe)
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b = _mk_bridge(ocf_port=None, default=49155)
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t0 = time.time()
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assert b._resolve_port() == 49154
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assert time.time() - t0 < 0.25 # did not wait out the 0.5s dead probes
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def test_cached_live_port_is_reused_without_rediscovery(monkeypatch):
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# Cached 49156 and the default 49155 are both live; the cache-first
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# path must return the cached port, not re-race the band (which would
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# tie-break to the default).
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monkeypatch.setattr(bridge, 'probe', _fake_probe({49155, 49156}))
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b = _mk_bridge(ocf_port=None, default=49155, discovered=49156)
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assert b._resolve_port() == 49156
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def test_autodiscovery_all_dead_raises_and_clears_cache(monkeypatch):
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monkeypatch.setattr(bridge, 'probe', _fake_probe(set()))
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b = _mk_bridge(ocf_port=None, discovered=49154)
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with pytest.raises(ConnectionError):
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b._resolve_port()
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assert b._discovered_port is None
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def test_candidate_ports_cover_band_plus_default(monkeypatch):
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b = _mk_bridge(ocf_port=None, default=49200)
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cands = b._candidate_ports()
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assert set(bridge.OCF_PORT_BAND) <= set(cands)
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assert 49200 in cands
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assert cands == sorted(cands)
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