From: Jeffrey Czyz Date: Wed, 27 Dec 2023 03:13:52 +0000 (-0500) Subject: Add a payments section to ChannelManager docs X-Git-Tag: v0.0.123-beta~15^2~2 X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=7cf899bfc9223f3736f9635d294c0485ddf5219d;p=rust-lightning Add a payments section to ChannelManager docs --- diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs index e35dcdf2a..dc170b652 100644 --- a/lightning/src/ln/channelmanager.rs +++ b/lightning/src/ln/channelmanager.rs @@ -1408,6 +1408,124 @@ where /// # } /// ``` /// +/// # Payments +/// +/// [`ChannelManager`] is responsible for sending, forwarding, and receiving payments through its +/// channels. A payment is typically initiated from a [BOLT 11] invoice or a [BOLT 12] offer, though +/// spontaneous (i.e., keysend) payments are also possible. Incoming payments don't require +/// maintaining any additional state as [`ChannelManager`] can reconstruct the [`PaymentPreimage`] +/// from the [`PaymentSecret`]. Sending payments, however, require tracking in order to retry failed +/// HTLCs. +/// +/// After a payment is initiated, it will appear in [`list_recent_payments`] until a short time +/// after either an [`Event::PaymentSent`] or [`Event::PaymentFailed`] is handled. Failed HTLCs +/// for a payment will be retried according to the payment's [`Retry`] strategy or until +/// [`abandon_payment`] is called. +/// +/// ## BOLT 11 Invoices +/// +/// The [`lightning-invoice`] crate is useful for creating BOLT 11 invoices. Specifically, use the +/// functions in its `utils` module for constructing invoices that are compatible with +/// [`ChannelManager`]. These functions serve as a convenience for building invoices with the +/// [`PaymentHash`] and [`PaymentSecret`] returned from [`create_inbound_payment`]. To provide your +/// own [`PaymentHash`], use [`create_inbound_payment_for_hash`] or the corresponding functions in +/// the [`lightning-invoice`] `utils` module. +/// +/// [`ChannelManager`] generates an [`Event::PaymentClaimable`] once the full payment has been +/// received. Call [`claim_funds`] to release the [`PaymentPreimage`], which in turn will result in +/// an [`Event::PaymentClaimed`]. +/// +/// ``` +/// # use lightning::events::{Event, EventsProvider, PaymentPurpose}; +/// # use lightning::ln::channelmanager::AChannelManager; +/// # +/// # fn example(channel_manager: T) { +/// # let channel_manager = channel_manager.get_cm(); +/// // Or use utils::create_invoice_from_channelmanager +/// let known_payment_hash = match channel_manager.create_inbound_payment( +/// Some(10_000_000), 3600, None +/// ) { +/// Ok((payment_hash, _payment_secret)) => { +/// println!("Creating inbound payment {}", payment_hash); +/// payment_hash +/// }, +/// Err(()) => panic!("Error creating inbound payment"), +/// }; +/// +/// // On the event processing thread +/// channel_manager.process_pending_events(&|event| match event { +/// Event::PaymentClaimable { payment_hash, purpose, .. } => match purpose { +/// PaymentPurpose::InvoicePayment { payment_preimage: Some(payment_preimage), .. } => { +/// assert_eq!(payment_hash, known_payment_hash); +/// println!("Claiming payment {}", payment_hash); +/// channel_manager.claim_funds(payment_preimage); +/// }, +/// PaymentPurpose::InvoicePayment { payment_preimage: None, .. } => { +/// println!("Unknown payment hash: {}", payment_hash); +/// }, +/// PaymentPurpose::SpontaneousPayment(payment_preimage) => { +/// assert_ne!(payment_hash, known_payment_hash); +/// println!("Claiming spontaneous payment {}", payment_hash); +/// channel_manager.claim_funds(payment_preimage); +/// }, +/// }, +/// Event::PaymentClaimed { payment_hash, amount_msat, .. } => { +/// assert_eq!(payment_hash, known_payment_hash); +/// println!("Claimed {} msats", amount_msat); +/// }, +/// // ... +/// # _ => {}, +/// }); +/// # } +/// ``` +/// +/// For paying an invoice, [`lightning-invoice`] provides a `payment` module with convenience +/// functions for use with [`send_payment`]. +/// +/// ``` +/// # use lightning::events::{Event, EventsProvider}; +/// # use lightning::ln::PaymentHash; +/// # use lightning::ln::channelmanager::{AChannelManager, PaymentId, RecentPaymentDetails, RecipientOnionFields, Retry}; +/// # use lightning::routing::router::RouteParameters; +/// # +/// # fn example( +/// # channel_manager: T, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, +/// # route_params: RouteParameters, retry: Retry +/// # ) { +/// # let channel_manager = channel_manager.get_cm(); +/// // let (payment_hash, recipient_onion, route_params) = +/// // payment::payment_parameters_from_invoice(&invoice); +/// let payment_id = PaymentId([42; 32]); +/// match channel_manager.send_payment( +/// payment_hash, recipient_onion, payment_id, route_params, retry +/// ) { +/// Ok(()) => println!("Sending payment with hash {}", payment_hash), +/// Err(e) => println!("Failed sending payment with hash {}: {:?}", payment_hash, e), +/// } +/// +/// let expected_payment_id = payment_id; +/// let expected_payment_hash = payment_hash; +/// assert!( +/// channel_manager.list_recent_payments().iter().find(|details| matches!( +/// details, +/// RecentPaymentDetails::Pending { +/// payment_id: expected_payment_id, +/// payment_hash: expected_payment_hash, +/// .. +/// } +/// )).is_some() +/// ); +/// +/// // On the event processing thread +/// channel_manager.process_pending_events(&|event| match event { +/// Event::PaymentSent { payment_hash, .. } => println!("Paid {}", payment_hash), +/// Event::PaymentFailed { payment_hash, .. } => println!("Failed paying {}", payment_hash), +/// // ... +/// # _ => {}, +/// }); +/// # } +/// ``` +/// /// # Persistence /// /// Implements [`Writeable`] to write out all channel state to disk. Implies [`peer_disconnected`] for @@ -1474,6 +1592,15 @@ where /// [`create_channel`]: Self::create_channel /// [`close_channel`]: Self::force_close_broadcasting_latest_txn /// [`force_close_broadcasting_latest_txn`]: Self::force_close_broadcasting_latest_txn +/// [BOLT 11]: https://github.com/lightning/bolts/blob/master/11-payment-encoding.md +/// [BOLT 12]: https://github.com/rustyrussell/lightning-rfc/blob/guilt/offers/12-offer-encoding.md +/// [`list_recent_payments`]: Self::list_recent_payments +/// [`abandon_payment`]: Self::abandon_payment +/// [`lightning-invoice`]: https://docs.rs/lightning_invoice/latest/lightning_invoice +/// [`create_inbound_payment`]: Self::create_inbound_payment +/// [`create_inbound_payment_for_hash`]: Self::create_inbound_payment_for_hash +/// [`claim_funds`]: Self::claim_funds +/// [`send_payment`]: Self::send_payment /// [`peer_disconnected`]: msgs::ChannelMessageHandler::peer_disconnected /// [`funding_created`]: msgs::FundingCreated /// [`funding_transaction_generated`]: Self::funding_transaction_generated