cync_lan (Home Assistant custom_component) v2.9.0

[github-actions[bot]]

New: cloud passthrough, in Configure -> General settings. Every device
session this server accepts is relayed on to the real Cync cloud from its
first byte, while the integration goes on parsing that same traffic and
controlling devices locally. Devices stay cloud-connected, so the vendor's
app, its schedules and its firmware delivery keep working through a server
that is also doing its own thing with everything it sees.

Understand what you are turning on. With DNS redirection in place, this
integration is normally the reason your devices never talk to the vendor
again. This option deliberately undoes that: your device traffic - and, if
the Cync app connects through this server too, your app traffic - goes to
the vendor. That is the entire feature, not a side effect. Off by default,
and the label in the options form says so rather than hiding it in a doc.

Why you might want it anyway: firmware updates only arrive over the cloud
connection, the Cync app stops being able to change anything once devices
are redirected, and a passthrough is the only way to watch the vendor's own
traffic against your own hardware - which is how most of the protocol in
this repository was worked out in the first place.

The relay is the same machinery behind the per-device "MITM mode" switch
that has shipped disabled-by-default for a while. What was missing was a way
to say "all of it", and a way to start relaying without the forced reconnect
that switch needs - a session enabled at accept time has not read a byte
yet, so the cloud sees the handshake from the beginning. See the library's
0.9.0 notes.

A cloud that cannot be reached is not fatal: the session logs and carries on
in ordinary local-only mode.

Requires cync-lan 0.9.1 or newer. Older releases ignore the variable
this writes, which would look identical to the cloud refusing your devices,
so the options flow checks and warns rather than letting that happen
silently - the same guard the hub-envelope toggle uses. (0.9.0 carries the
feature; 0.9.1 adds the type annotations this repository's mypy job needs,
and requirements_test.txt moves with it - it had been pinned at 0.4.0
while the manifest asked for far newer, so CI was exercising a library the
integration declared it could not work with.)

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This discussion was created from the release cync_lan (Home Assistant custom_component) v2.9.0.