lgtv-sdp

lgtv-sdp

tl;dr: LG 'smart' TV and projector devices want to phone home to get the date and time and this daemon fixes these defective devices.

You just got a fancy new display from LG! Congratulations!

Unfortunately, when you decided to make it behave itself by firewalling it, it stopped automatically updating its time and date. Maybe your display is the amazing HU-80 CineBeam portable 4K laster projector and its time and date get thrown away every time you store it. Or maybe you have a TV on a smart plug. Or maybe your power is intermittent. Or maybe you just never want to have to worry about date and time on a bloody 'smart' display device. It's so nice to just have the YouTube app on the device work properly... so easy. Except Google serves TLS certificates with NotValidBefore set so the YouTube app is unusable until you set the date and time manually. :-( And the device doesn't listen to the NTP server setting that it itself requests via DHCP. :-(

Luckily, no certificate checking is done on the initial phone home request it makes and the server response contains an HTTP header with the current time in milliseconds since the UNIX epoch. Whew!

Installation for the impatient

1. Download correct build for your platform.
2. Unpack archive (it will create a subdirectory for you) where you want to 'install' the daemon.
3. cd into the installation directory and run sudo ./lgtv-sdp -s install BIND_ADDRESS where BIND_ADDRESS is the IP you want the daemon to listen on or 0.0.0.0 or :: for all addresses.
4. Redirect DNS for *.lgtvsdp.com to an address where the daemon is listening.
5. Enjoy your LG display with the correct time!

Building

1. Ensure go 1.14 is installed.
2. Clone this repo.
3. go build or GOOS=TARGET_OS GOARCH=TARGET_ARCH go build

How it works

TLS

The daemon will check if key.pem and cert.pem files are present in its directory and, if they aren't, will create new certificate authority (CA) certificate and a domain certificate and sign the domain certificate with the CA key. The daemon will then start an HTTPS server on the standard port 443.

API

The HTTPS server will respond with the contents of initservices.json with the headers in the files under initservices.headers/ to requests for any paths. The X-Server-Time header will always be set to the number of milliseconds since the UNIX epoch. You may be able to customize more aspects of your device(s) by sending specific headers or JSON content but none of that is necessary to set the time. Home screen widgets and further request behavior are both probably controllable with specific responses. Your contributions are very welcome.

Help wanted

We need:

1. A Windows service tester
2. LG webOS 4 and 5 testers
3. A free world

Contributing

Patches, documentation, cool features, and more are welcome. Negativity and lawsuits are not welcome.