Utility for paying for an Offer
[rust-lightning] / lightning / src / ln / channelmanager.rs
index 74fef11e9132c65e05818d07874baa33952d7f53..3e7bac3d43b2d140cffaef960673b425420b74b5 100644 (file)
@@ -56,10 +56,10 @@ use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError};
 use crate::ln::outbound_payment;
 use crate::ln::outbound_payment::{OutboundPayments, PaymentAttempts, PendingOutboundPayment, SendAlongPathArgs, StaleExpiration};
 use crate::ln::wire::Encode;
-use crate::offers::offer::{DerivedMetadata, OfferBuilder};
+use crate::offers::offer::{DerivedMetadata, Offer, OfferBuilder};
 use crate::offers::parse::Bolt12SemanticError;
 use crate::offers::refund::RefundBuilder;
-use crate::onion_message::{OffersMessage, PendingOnionMessage};
+use crate::onion_message::{Destination, OffersMessage, PendingOnionMessage};
 use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient, SignerProvider, WriteableEcdsaChannelSigner};
 use crate::util::config::{UserConfig, ChannelConfig, ChannelConfigUpdate};
 use crate::util::wakers::{Future, Notifier};
@@ -7359,6 +7359,92 @@ where
                Ok(builder)
        }
 
+       /// Pays for an [`Offer`] using the given parameters by creating an [`InvoiceRequest`] and
+       /// enqueuing it to be sent via an onion message. [`ChannelManager`] will pay the actual
+       /// [`Bolt12Invoice`] once it is received.
+       ///
+       /// Uses [`InvoiceRequestBuilder`] such that the [`InvoiceRequest`] it builds is recognized by
+       /// the [`ChannelManager`] when handling a [`Bolt12Invoice`] message in response to the request.
+       /// The optional parameters are used in the builder, if `Some`:
+       /// - `quantity` for [`InvoiceRequest::quantity`] which must be set if
+       ///   [`Offer::expects_quantity`] is `true`.
+       /// - `amount_msats` if overpaying what is required for the given `quantity` is desired, and
+       /// - `payer_note` for [`InvoiceRequest::payer_note`].
+       ///
+       /// The provided `payment_id` is used to ensure that only one invoice is paid for the request
+       /// when received. See [Avoiding Duplicate Payments] for other requirements once the payment has
+       /// been sent. To revoke the request, use [`ChannelManager::abandon_payment`] prior to receiving
+       /// the invoice.
+       ///
+       /// Errors if a duplicate `payment_id` is provided given the caveats in the aforementioned link.
+       ///
+       /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+       /// [`InvoiceRequest::quantity`]: crate::offers::invoice_request::InvoiceRequest::quantity
+       /// [`InvoiceRequest::payer_note`]: crate::offers::invoice_request::InvoiceRequest::payer_note
+       /// [`InvoiceRequestBuilder`]: crate::offers::invoice_request::InvoiceRequestBuilder
+       /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
+       /// [Avoiding Duplicate Payments]: #avoiding-duplicate-payments
+       pub fn pay_for_offer(
+               &self, offer: &Offer, quantity: Option<u64>, amount_msats: Option<u64>,
+               payer_note: Option<String>, payment_id: PaymentId, retry_strategy: Retry,
+               max_total_routing_fee_msat: Option<u64>
+       ) -> Result<(), Bolt12SemanticError> {
+               let expanded_key = &self.inbound_payment_key;
+               let entropy = &*self.entropy_source;
+               let secp_ctx = &self.secp_ctx;
+
+               let builder = offer
+                       .request_invoice_deriving_payer_id(expanded_key, entropy, secp_ctx, payment_id)?
+                       .chain_hash(self.chain_hash)?;
+               let builder = match quantity {
+                       None => builder,
+                       Some(quantity) => builder.quantity(quantity)?,
+               };
+               let builder = match amount_msats {
+                       None => builder,
+                       Some(amount_msats) => builder.amount_msats(amount_msats)?,
+               };
+               let builder = match payer_note {
+                       None => builder,
+                       Some(payer_note) => builder.payer_note(payer_note),
+               };
+
+               let invoice_request = builder.build_and_sign()?;
+               let reply_path = self.create_one_hop_blinded_path();
+
+               let expiration = StaleExpiration::TimerTicks(1);
+               self.pending_outbound_payments
+                       .add_new_awaiting_invoice(
+                               payment_id, expiration, retry_strategy, max_total_routing_fee_msat
+                       )
+                       .map_err(|_| Bolt12SemanticError::DuplicatePaymentId)?;
+
+               let mut pending_offers_messages = self.pending_offers_messages.lock().unwrap();
+               if offer.paths().is_empty() {
+                       let message = PendingOnionMessage {
+                               contents: OffersMessage::InvoiceRequest(invoice_request),
+                               destination: Destination::Node(offer.signing_pubkey()),
+                               reply_path: Some(reply_path),
+                       };
+                       pending_offers_messages.push(message);
+               } else {
+                       // Send as many invoice requests as there are paths in the offer (with an upper bound).
+                       // Using only one path could result in a failure if the path no longer exists. But only
+                       // one invoice for a given payment id will be paid, even if more than one is received.
+                       const REQUEST_LIMIT: usize = 10;
+                       for path in offer.paths().into_iter().take(REQUEST_LIMIT) {
+                               let message = PendingOnionMessage {
+                                       contents: OffersMessage::InvoiceRequest(invoice_request.clone()),
+                                       destination: Destination::BlindedPath(path.clone()),
+                                       reply_path: Some(reply_path.clone()),
+                               };
+                               pending_offers_messages.push(message);
+                       }
+               }
+
+               Ok(())
+       }
+
        /// Gets a payment secret and payment hash for use in an invoice given to a third party wishing
        /// to pay us.
        ///