Explore sending and receiving of custom onion messages

[tnull]

We should consider exposing a simple interface to send/receive custom onion messages.

The receive part could potentially be handled through a new event type.

[TheBlueMatt]

How do you think about this in relation to the ldk-node scope? Its definitely something that most users will have no need for, though is of course quite trivial.

[moneyball]

That was going to be my question too.

[tnull]

Yup, I agree that it's kinda out-of-scope of the minimal API, hence the 'Explore' in the title. We got some requests for it (e.g., for lndk testing), and I generally like the idea of having a simple tool available that allows people to start using/playing with OMs. Still, it might be a feature that anyone willing to fork the codebase could easily add on their own if they wanted.

[moneyball]

Hmmm doesn't LNDK use LDK not LDK Node?

[TheBlueMatt]

I generally like the idea of having a simple tool available that allows people to start using/playing with OMs

If that's the goal we should have a demo of a simple rust project that spins up a node that can only send +receive OMs without anything else, but that doesn't help those wanting to use it in conjunction with a real node of course.

[tnull]

Hmmm doesn't LNDK use LDK not LDK Node?

They are looking to use LDK Node for (integration) testing purposes, i.e., to have an easy way to spawn up a node in CI and see if messages come through.

If that's the goal we should have a demo of a simple rust project that spins up a node that can only send +receive OMs without anything else, but that doesn't help those wanting to use it in conjunction with a real node of course.

Right. Just from the experience over the last months I can see that there is a lot of utility in having a quick way to spawn up a full lightning node and interact with it programatically. It's just great to be able to connect to any node and test something out in ~5 lines of Rust. Longer term it might be nice to have a tool providing this kind of 'swiss army knife' utility, which however doesn't mean it has to be LDK Node mainline. Another example for a 'nice to have' utility would probably be probing capabilities (see #19).

As said, I agree that features such as OMs are out-of-scope for LDK Node (at least for now). Main intention here was to document the feature request and possibly come back to it / explore its feasibility in the future.

[tnull]

This recently became a priority again as users want to be able to send/receive OMs via LDK Node. Adding to the 0.3 milestone.