Files
localthings/custom_components/localthings/const.py
T
Jack Nagy 0ebcfb00ff fix: bind a fixed DTLS source port per device to evict stale sessions
When HA restarts without a clean DTLS close_notify (crash, host reboot),
the appliance keeps an orphaned DTLS association keyed to the client's
(IP, source port). Reconnecting from a fresh ephemeral port looks like a
new peer, so the device holds the orphan until its own timer reaps it,
which is 5 to 15 min on always-on appliances (fridges), during which the
new session's first reads hang. This is the root cause behind the repeated
"DTLS handshake timeout" reconnect storms on always-on devices (#119).

Bind a deterministic source port per device so every reconnect re-handshakes
over the same 5-tuple, which the device must treat as a rebooted peer and
evict the old association for (RFC 6347 §4.2.8). Recovery drops from a
device-timer wait to a single handshake.

The port must be stable across restarts and unique per device on the HA host
(the library socket is unconnected, so a shared source port would cross-
deliver datagrams). _local_source_port() uses the host's last IPv4 octet as
the offset from DTLS_LOCAL_PORT_BASE (unique on a /24), with a CRC32 fallback
for non-IPv4 hosts.

Requires smartthings-local >= 0.1.1, which adds DtlsCoapSession(local_port=).
The fix is backwards compatible upstream: local_port defaults to None
(previous ephemeral-port behaviour).

Root-caused and verified upstream in QuiteYellow/SmartThings-Local#14
(bench-verified on oven + dryer, field-verified on an always-on fridge
across repeated restarts).
2026-07-27 19:17:39 +01:00

57 lines
2.4 KiB
Python

DOMAIN = "localthings"
PLATFORMS = [
"sensor", "binary_sensor", "switch", "number", "select", "button",
"time", "climate", "fan",
]
CONF_HOST = "host"
CONF_PORT = "port"
CONF_CA_CERT_PEM = "ca_cert_pem"
CONF_CA_KEY_PEM = "ca_key_pem"
CONF_LEAF_CERT_PEM = "leaf_cert_pem"
CONF_LEAF_KEY_PEM = "leaf_key_pem"
# Options-flow key (entry.options, not entry.data): lets a user override the
# device-wide remote-control-off write block for a specific device (issue
# #54). Some devices report remote control off yet still accept certain
# writes (e.g. default detergent/softener dosing on a washer, applied even
# to the built-in programs) -- the block exists to give a clear error
# instead of a silent device-side rejection, but that assumption doesn't
# hold for every model. Defaults to False (block stays on) everywhere it's
# read, so devices this doesn't apply to see no behavior change.
CONF_BYPASS_REMOTE_CONTROL = "bypass_remote_control_lock"
# The DTLS/CoAP local API binds somewhere in this ephemeral range; which port
# depends on firmware. Newer builds answer on 49154/49155, but older ones have
# been seen as low as 49153, so we sweep the whole range for a live UDP port
# before attempting the (expensive) DTLS handshake.
PROBE_PORT_RANGE = list(range(49152, 49161))
# Ports we've historically seen complete a DTLS handshake. When more than one
# port in the range looks live, these are tried first.
PREFERRED_PROBE_PORTS = [49154, 49155]
# Per-port timeout for the cheap UDP liveness sweep. Closed ports return an
# ICMP port-unreachable almost immediately; a live-but-silent port is only
# detected by this timeout elapsing, so keep it short.
LIVENESS_PROBE_TIMEOUT_S = 1.5
# Deadline for the blockwise /device/0 GET during the config-flow probe. The
# slowest device observed returns a full dump in ~8s, so 10s leaves headroom
# without stalling setup; it matches the per-resource read timeout elsewhere.
PROBE_GET_TIMEOUT_S = 10.0
# Base for the local (client-side) DTLS source port, distinct from the
# destination probe ports above. See coordinator._local_source_port for why a
# fixed per-device source port matters and how the per-device offset is
# derived. Base mirrors the upstream smartthings-local reference bridge.
# Requires smartthings-local >= 0.1.1.
DTLS_LOCAL_PORT_BASE = 49700
SUMMARY_INTERVAL_S = 30.0
DEVICE_SUPPORT_ISSUE_URL = (
"https://github.com/mbillow/localthings/issues/new?template=device-support.yml"
)