[Feature] Support triggering firmware upgrade through mqtt (in LAN mode)

[pimlie]

Describe the feature

It turns out it is possible to trigger a firmware upgrade through mqtt, credits for this go to the user halwin on cafe.naver.com. It works by posting a json with the latest firmware description over mqtt (see prev link for details). The printer can then download the firmware directly from the CDN, without having to be signed in to the cloud.

❗ The printer still needs an internet connection to download the actual firmware files from bbl's cdn, so it doesn't work for air-gapped printers. This is because the ota upgrade json is signed with a gpg key (as are the firmware files), so I guess somebody would probably need to dissect the bambulab firmware and overwrite bbl's public gpg key with a custom key before you can fully trigger a firmware upload on an air-gapped printer.

The json with the latest firmware update can only be downloaded when you are signed in, this repo keeps track of the latest available firmwares. Note that that repo is relying on users with a cloud account to update those ota upgrade json's.

What device is this for?

X1/P1/A1

Other Information

See :

• https://cafe.naver.com/bambulab/3353 This describes the upgrade procedure, requirements etc
• https://github.com/lunDreame/user-bambulab-firmware/ Repo containing latest firmware upgrades
• https://github.com/yeorinhieut/bambu-updater Webbased update tool using a local proxy