Expose HTLCs in `ChannelDetails`

[TheBlueMatt]

We should expose the list of in-flight HTLCs in ChannelDetails, cause why not. This should let us better figure out what the timeline is for the channel close. We should also expose if a channel is actively shutting down and maybe if a peer is currently connected in ChannelDetails. May help with visibility into #2086.

[ayeankit]

hey @TheBlueMatt, Is this still open? i would like to work on this.

[TheBlueMatt]

Sure, go for it!

[TheBlueMatt]

I think, rather than listing explicit HTLCs pending, maybe we should just expose the total in flight amounts, preferably by type (outbound-vs-forwarded).

[aniket2405]

hey, it seems that the PR for this was not accepted and closed. Is this still open then? If yes, I would like to work on this.

[aniket2405]

Do these fields in the ChannelDetails struct in the ln::channelmanager module make sense to expose the HTLCs? The first is present already, what about the rest?

pub struct ChannelDetails {
pub channel_id: [u8; 32],
pub local_balance: u64,
pub remote_balance: u64,
pub remote_pubkey: PublicKey,
pub channel_value_satoshis: u64,
pub user_id: UserId,
pub in_flight_htlcs: Vec<(PaymentHash, u64, HTLCType)>,
pub is_shutting_down: bool,
pub peer_connected: bool,
}

[TheBlueMatt]

I don't think we need to expose the payment hash, but rather in HTLCType we should expose eg the previous channel and htlc_id for forwarded payments.

[tlulu]

Is anyone actively working on this? If not, I would like to work on this. For context, I want to expose an HTLC's cltv_expiry.

Alternatively would an API to query LDK be better? E.g

fn get_htlc(payment_hash: PaymentHash) -> HtlcDetails

pub struct HtlcDetails {
  pub absolute_cltv_expiry: Duration
  pub payment_hash: PaymentHash
}

[TheBlueMatt]

I think @wvanlint may be - is that still being worked on?

[wvanlint]

Yes, sent out #2442 for review.