lsps2 fee and channel configuration

[johncantrell97]

Allows LSP user to configure fee and channel parameters with sane defaults.

• Set fees based on a multiple of the current fee rates based on their fee estimator.
• Set min/max payment sizes
• Set min/max channel sizes
• Set forwarding fees on JIT channels opened
• Set channel size based on payment size

/// How many times the current funding tx fee rates should charge for a channel.
pub funding_tx_fee_multiplier: f32,
/// What fee rate estimate to use when calculating opening fee.
pub funding_tx_fee_multiplier_source_rate: ConfirmationTarget,
/// A minimum fee you will charge regardless of current fee rates.
pub minimum_min_fee_msat: u64,
/// How many millisatoshis to charge for every million millisatoshis received
/// in the initial payment of a JIT channel.
pub proportional_fee: u32,
/// How many minutes the offer we present to the client is valid for.
pub fee_valid_for_minutes: i64,
/// How many blocks we guarantee we will keep the channel open for.
pub min_lifetime_blocks: u32,
/// Maximum number of blocks the client can set our to_self_delay to.
/// How long we would have to wait to get our funds back if we need to force close the channel.
pub max_client_to_self_delay_blocks: u32,
/// The minimum payment size above our minimum fee we will allow.
pub min_payment_size_buffer_msats: u64,
/// The maximum payment size we will allow a user to receive during the JIT channel opening flow.
pub max_payment_size_msats: u64,
/// The cltv_expiry_delta the client sets on the invoice to be paid by payer.
/// How long we have to claim HTLC-encumbered balances when channel is force-closed.
pub client_invoice_cltv_expiry_delta: u32,
/// What channel size we should open based on the incoming payment size.
pub channel_size_factor: f64,
/// The minimum channel size we will open regardless of payment size.
pub min_channel_size_sats: u64,
/// The base fee in msats for forwarding htlcs over the channel once open.
pub forwarding_fee_base_msat: u32,
/// The fee in sats per million satoshis being forwarded over the channel once open.
pub forwarding_fee_proportional_millionths: u32,

[tnull]

How do you arrive at this value? Could you add a comment?

[tnull]

I think this is great, but I'm a bit unsure if we should just keep the "no-limits" LSP mode for now to reduce friction for the demo as much as possible?

[johncantrell97]

I think this is great, but I'm a bit unsure if we should just keep the "no-limits" LSP mode for now to reduce friction for the demo as much as possible?

Yeah, seems reasonable to wait until post hack week.