--- /dev/null
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Data structures and encoding for `offer` messages.
+
+use bitcoin::blockdata::constants::ChainHash;
+use bitcoin::network::constants::Network;
+use bitcoin::secp256k1::PublicKey;
+use core::num::NonZeroU64;
+use core::time::Duration;
+use crate::ln::features::OfferFeatures;
+use crate::onion_message::BlindedPath;
+use crate::util::string::PrintableString;
+
+use crate::prelude::*;
+
+#[cfg(feature = "std")]
+use std::time::SystemTime;
+
+/// An `Offer` is a potentially long-lived proposal for payment of a good or service.
+///
+/// An offer is a precursor to an `InvoiceRequest`. A merchant publishes an offer from which a
+/// customer may request an `Invoice` for a specific quantity and using an amount sufficient to
+/// cover that quantity (i.e., at least `quantity * amount`). See [`Offer::amount`].
+///
+/// Offers may be denominated in currency other than bitcoin but are ultimately paid using the
+/// latter.
+///
+/// Through the use of [`BlindedPath`]s, offers provide recipient privacy.
+#[derive(Clone, Debug)]
+pub struct Offer {
+ // The serialized offer. Needed when creating an `InvoiceRequest` if the offer contains unknown
+ // fields.
+ bytes: Vec<u8>,
+ contents: OfferContents,
+}
+
+/// The contents of an [`Offer`], which may be shared with an `InvoiceRequest` or an `Invoice`.
+#[derive(Clone, Debug)]
+pub(crate) struct OfferContents {
+ chains: Option<Vec<ChainHash>>,
+ metadata: Option<Vec<u8>>,
+ amount: Option<Amount>,
+ description: String,
+ features: OfferFeatures,
+ absolute_expiry: Option<Duration>,
+ issuer: Option<String>,
+ paths: Option<Vec<BlindedPath>>,
+ quantity_max: Option<u64>,
+ signing_pubkey: Option<PublicKey>,
+}
+
+impl Offer {
+ // TODO: Return a slice once ChainHash has constants.
+ // - https://github.com/rust-bitcoin/rust-bitcoin/pull/1283
+ // - https://github.com/rust-bitcoin/rust-bitcoin/pull/1286
+ /// The chains that may be used when paying a requested invoice (e.g., bitcoin mainnet).
+ /// Payments must be denominated in units of the minimal lightning-payable unit (e.g., msats)
+ /// for the selected chain.
+ pub fn chains(&self) -> Vec<ChainHash> {
+ self.contents.chains
+ .as_ref()
+ .cloned()
+ .unwrap_or_else(|| vec![ChainHash::using_genesis_block(Network::Bitcoin)])
+ }
+
+ // TODO: Link to corresponding method in `InvoiceRequest`.
+ /// Opaque bytes set by the originator. Useful for authentication and validating fields since it
+ /// is reflected in `invoice_request` messages along with all the other fields from the `offer`.
+ pub fn metadata(&self) -> Option<&Vec<u8>> {
+ self.contents.metadata.as_ref()
+ }
+
+ /// The minimum amount required for a successful payment of a single item.
+ pub fn amount(&self) -> Option<&Amount> {
+ self.contents.amount.as_ref()
+ }
+
+ /// A complete description of the purpose of the payment. Intended to be displayed to the user
+ /// but with the caveat that it has not been verified in any way.
+ pub fn description(&self) -> PrintableString {
+ PrintableString(&self.contents.description)
+ }
+
+ /// Features pertaining to the offer.
+ pub fn features(&self) -> &OfferFeatures {
+ &self.contents.features
+ }
+
+ /// Duration since the Unix epoch when an invoice should no longer be requested.
+ ///
+ /// If `None`, the offer does not expire.
+ pub fn absolute_expiry(&self) -> Option<Duration> {
+ self.contents.absolute_expiry
+ }
+
+ /// Whether the offer has expired.
+ #[cfg(feature = "std")]
+ pub fn is_expired(&self) -> bool {
+ match self.absolute_expiry() {
+ Some(seconds_from_epoch) => match SystemTime::UNIX_EPOCH.elapsed() {
+ Ok(elapsed) => elapsed > seconds_from_epoch,
+ Err(_) => false,
+ },
+ None => false,
+ }
+ }
+
+ /// The issuer of the offer, possibly beginning with `user@domain` or `domain`. Intended to be
+ /// displayed to the user but with the caveat that it has not been verified in any way.
+ pub fn issuer(&self) -> Option<PrintableString> {
+ self.contents.issuer.as_ref().map(|issuer| PrintableString(issuer.as_str()))
+ }
+
+ /// Paths to the recipient originating from publicly reachable nodes. Blinded paths provide
+ /// recipient privacy by obfuscating its node id.
+ pub fn paths(&self) -> &[BlindedPath] {
+ self.contents.paths.as_ref().map(|paths| paths.as_slice()).unwrap_or(&[])
+ }
+
+ /// The quantity of items supported.
+ pub fn supported_quantity(&self) -> Quantity {
+ match self.contents.quantity_max {
+ Some(0) => Quantity::Unbounded,
+ Some(n) => Quantity::Bounded(NonZeroU64::new(n).unwrap()),
+ None => Quantity::Bounded(NonZeroU64::new(1).unwrap()),
+ }
+ }
+
+ /// The public key used by the recipient to sign invoices.
+ pub fn signing_pubkey(&self) -> PublicKey {
+ self.contents.signing_pubkey.unwrap()
+ }
+}
+
+/// The minimum amount required for an item in an [`Offer`], denominated in either bitcoin or
+/// another currency.
+#[derive(Clone, Debug)]
+pub enum Amount {
+ /// An amount of bitcoin.
+ Bitcoin {
+ /// The amount in millisatoshi.
+ amount_msats: u64,
+ },
+ /// An amount of currency specified using ISO 4712.
+ Currency {
+ /// The currency that the amount is denominated in.
+ iso4217_code: CurrencyCode,
+ /// The amount in the currency unit adjusted by the ISO 4712 exponent (e.g., USD cents).
+ amount: u64,
+ },
+}
+
+/// An ISO 4712 three-letter currency code (e.g., USD).
+pub type CurrencyCode = [u8; 3];
+
+/// Quantity of items supported by an [`Offer`].
+pub enum Quantity {
+ /// Up to a specific number of items (inclusive).
+ Bounded(NonZeroU64),
+ /// One or more items.
+ Unbounded,
+}
projects / rust-lightning / commitdiff