watchtowers: warn or disallow users from connecting the the wt server running on the same node as the wtclient

[xanoni]

Background

1. I noticed that I can connect a node to its own watchtower, and it even starts backing up. Maybe we should warn users somehow that this is not how it's supposed to be done?

2. When I first set up watchtowers I didn't realize that the PubKey / onion address was different from the actual LND node itself ... however, it still let me connect and lncli wtclient towers shows them as valid watchtowers ... wouldn't it be better if the client rejected pubkeys/addresses that are not watchtowers, or at least indicate that something is broken?

3. What's the reason in the first place that the pubkey and address of the watchtower have to differ from the main node? Is this just a safety measure while the feature is being tested by volunteers?

Thank you (leaving the stuff below so the bot doesn't punish me for ignoring the template).

Your environment

• version of lnd
• which operating system (uname -a on *Nix)
• version of btcd, bitcoind, or other backend
• any other relevant environment details

Steps to reproduce

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Expected behaviour

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Actual behaviour

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[xanoni]

Saw that point 2 is also addressed here: #5361

[ellemouton]

Hi @xanoni !

First of all, good point: there should definitely be a warning or it should strictly disallow users from connecting to their own binary.

Secondly, the reason for the main node ID not being used is to maintain privacy. We want to be able to use a watch tower without giving away what our main node ID is.

[Chinwendu20]

Please I would like to work on this issue

[anibilthare]

@ellemouton I need your help, I tried to implement this but I'm not able to test my changes as my wtclient add call gets stuck.

lnd node output

lncli add call

[ellemouton]

@anibilthare - it just looks like your node isnt synced. If you are on regtest, try mining a few blocs

(also just for future: if you want to share a really large piece of text like the config file above, consider adding a link to the text instead as it takes a lot of space on this page)

[anibilthare]

Hi, Thanks. Yeah mining worked. Thanks.

Yeah I'll keep that in mind.

[murraystewart96]

Went to review this PR and saw good feedback. Issue seems stale at this point so i thought i'd have a go implementing it. Hope this helps!

#10811