HDCP protocol support (pre 2012 LG TV)

[whyscream]

New attempt on #5

• Connect to the TV
• Trigger the TV to display a pairing code
• Use pairing code to authenticate
• Execute commands
• Implement HDCP-specific list of commands (command IDs)
• Query TV status (required for volume change and channel switching)
• ...

I have a LG 42LW650S from 2011, running Netcast and an 'LG HDCP Server' according to the HTTP response headers.

I found some earlier (partial) implementations and discussions of this interface at:

• https://pastebin.com/Ve0YVTfq
• https://community.home-assistant.io/t/workaround-lg-tv-remote/188
• https://community.home-assistant.io/t/support-for-pre-2012-models-lg-nestcast-tvs-needed/6476
• https://github.com/ypid/lgcommander/blob/master/README.md
• https://github.com/ConnectSDK/Connect-SDK-Windows/blob/master/Service/NetcastTVService.cs

[whyscream]

The data querying requests all go nowhere: GET /hdcp/api/data?target=foo HTTP/1.1" returns a HTTP 400. This blocks support for higher level functionality like set_volume, change_channel. There is nothing about querying in the other implementations either. Maybe it was never supported? Some further research needed.

The interesting part is that not all requests are handled equal: some get a HTTP 400, others a HTTP 401. There is no difference in whether or not the User-Agent: UDAP/2.0 header is sent along.

DEBUG:pylgnetcast.pylgnetcast:_send_to_tv: message_type=data, message=None, payload={'target': 'cur_channel'}
DEBUG:urllib3.connectionpool:Starting new HTTP connection (1): lgtv.fritz.box:8080
DEBUG:urllib3.connectionpool:http://lgtv.fritz.box:8080 "GET /hdcp/api/data?target=cur_channel HTTP/1.1" 401 160
DEBUG:pylgnetcast.pylgnetcast:_send_to_tv: message_type=data, message=None, payload={'target': 'volume_info'}
DEBUG:urllib3.connectionpool:Starting new HTTP connection (1): lgtv.fritz.box:8080
DEBUG:urllib3.connectionpool:http://lgtv.fritz.box:8080 "GET /hdcp/api/data?target=volume_info HTTP/1.1" 400 159
DEBUG:pylgnetcast.pylgnetcast:_send_to_tv: message_type=data, message=None, payload={'target': 'context_ui'}
DEBUG:urllib3.connectionpool:Starting new HTTP connection (1): lgtv.fritz.box:8080
DEBUG:urllib3.connectionpool:http://lgtv.fritz.box:8080 "GET /hdcp/api/data?target=context_ui HTTP/1.1" 401 160
DEBUG:pylgnetcast.pylgnetcast:_send_to_tv: message_type=data, message=None, payload={'target': 'is_3d'}
DEBUG:urllib3.connectionpool:Starting new HTTP connection (1): lgtv.fritz.box:8080
DEBUG:urllib3.connectionpool:http://lgtv.fritz.box:8080 "GET /hdcp/api/data?target=is_3d HTTP/1.1" 400 159