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| 1 | +// This file is Copyright its original authors, visible in version control |
| 2 | +// history. |
| 3 | +// |
| 4 | +// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE |
| 5 | +// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| 6 | +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option. |
| 7 | +// You may not use this file except in accordance with one or both of these |
| 8 | +// licenses. |
| 9 | + |
| 10 | +//! Data structures and encoding for `offer` messages. |
| 11 | +
|
| 12 | +use bitcoin::blockdata::constants::ChainHash; |
| 13 | +use bitcoin::network::constants::Network; |
| 14 | +use bitcoin::secp256k1::PublicKey; |
| 15 | +use core::num::NonZeroU64; |
| 16 | +use core::time::Duration; |
| 17 | +use crate::ln::features::OfferFeatures; |
| 18 | +use crate::onion_message::BlindedPath; |
| 19 | +use crate::util::string::PrintableString; |
| 20 | + |
| 21 | +use crate::prelude::*; |
| 22 | + |
| 23 | +#[cfg(feature = "std")] |
| 24 | +use std::time::SystemTime; |
| 25 | + |
| 26 | +/// An `Offer` is a potentially long-lived proposal for payment of a good or service. |
| 27 | +/// |
| 28 | +/// An offer is a precursor to an `InvoiceRequest`. A merchant publishes an offer from which a |
| 29 | +/// customer may request an `Invoice` for a specific quantity and using an amount sufficient to |
| 30 | +/// cover that quantity (i.e., at least `quantity * amount`). See [`Offer::amount`]. |
| 31 | +/// |
| 32 | +/// Offers may be denominated in currency other than bitcoin but are ultimately paid using the |
| 33 | +/// latter. |
| 34 | +/// |
| 35 | +/// Through the use of [`BlindedPath`]s, offers provide recipient privacy. |
| 36 | +#[derive(Clone, Debug)] |
| 37 | +pub struct Offer { |
| 38 | + // The serialized offer. Needed when creating an `InvoiceRequest` if the offer contains unknown |
| 39 | + // fields. |
| 40 | + bytes: Vec<u8>, |
| 41 | + contents: OfferContents, |
| 42 | +} |
| 43 | + |
| 44 | +/// The contents of an [`Offer`], which may be shared with an `InvoiceRequest` or an `Invoice`. |
| 45 | +#[derive(Clone, Debug)] |
| 46 | +pub(crate) struct OfferContents { |
| 47 | + chains: Option<Vec<ChainHash>>, |
| 48 | + metadata: Option<Vec<u8>>, |
| 49 | + amount: Option<Amount>, |
| 50 | + description: String, |
| 51 | + features: OfferFeatures, |
| 52 | + absolute_expiry: Option<Duration>, |
| 53 | + issuer: Option<String>, |
| 54 | + paths: Option<Vec<BlindedPath>>, |
| 55 | + quantity_max: Option<u64>, |
| 56 | + signing_pubkey: Option<PublicKey>, |
| 57 | +} |
| 58 | + |
| 59 | +impl Offer { |
| 60 | + // TODO: Return a slice once ChainHash has constants. |
| 61 | + // - https://github.com/rust-bitcoin/rust-bitcoin/pull/1283 |
| 62 | + // - https://github.com/rust-bitcoin/rust-bitcoin/pull/1286 |
| 63 | + /// The chains that may be used when paying a requested invoice (e.g., bitcoin mainnet). |
| 64 | + /// Payments must be denominated in units of the minimal lightning-payable unit (e.g., msats) |
| 65 | + /// for the selected chain. |
| 66 | + pub fn chains(&self) -> Vec<ChainHash> { |
| 67 | + self.contents.chains |
| 68 | + .as_ref() |
| 69 | + .cloned() |
| 70 | + .unwrap_or_else(|| vec![ChainHash::using_genesis_block(Network::Bitcoin)]) |
| 71 | + } |
| 72 | + |
| 73 | + // TODO: Link to corresponding method in `InvoiceRequest`. |
| 74 | + /// Opaque bytes set by the originator. Useful for authentication and validating fields since it |
| 75 | + /// is reflected in `invoice_request` messages along with all the other fields from the `offer`. |
| 76 | + pub fn metadata(&self) -> Option<&Vec<u8>> { |
| 77 | + self.contents.metadata.as_ref() |
| 78 | + } |
| 79 | + |
| 80 | + /// The minimum amount required for a successful payment of a single item. |
| 81 | + pub fn amount(&self) -> Option<&Amount> { |
| 82 | + self.contents.amount.as_ref() |
| 83 | + } |
| 84 | + |
| 85 | + /// A complete description of the purpose of the payment. Intended to be displayed to the user |
| 86 | + /// but with the caveat that it has not been verified in any way. |
| 87 | + pub fn description(&self) -> PrintableString { |
| 88 | + PrintableString(&self.contents.description) |
| 89 | + } |
| 90 | + |
| 91 | + /// Features pertaining to the offer. |
| 92 | + pub fn features(&self) -> &OfferFeatures { |
| 93 | + &self.contents.features |
| 94 | + } |
| 95 | + |
| 96 | + /// Duration since the Unix epoch when an invoice should no longer be requested. |
| 97 | + /// |
| 98 | + /// If `None`, the offer does not expire. |
| 99 | + pub fn absolute_expiry(&self) -> Option<Duration> { |
| 100 | + self.contents.absolute_expiry |
| 101 | + } |
| 102 | + |
| 103 | + /// Whether the offer has expired. |
| 104 | + #[cfg(feature = "std")] |
| 105 | + pub fn is_expired(&self) -> bool { |
| 106 | + match self.absolute_expiry() { |
| 107 | + Some(seconds_from_epoch) => match SystemTime::UNIX_EPOCH.elapsed() { |
| 108 | + Ok(elapsed) => elapsed > seconds_from_epoch, |
| 109 | + Err(_) => false, |
| 110 | + }, |
| 111 | + None => false, |
| 112 | + } |
| 113 | + } |
| 114 | + |
| 115 | + /// The issuer of the offer, possibly beginning with `user@domain` or `domain`. Intended to be |
| 116 | + /// displayed to the user but with the caveat that it has not been verified in any way. |
| 117 | + pub fn issuer(&self) -> Option<PrintableString> { |
| 118 | + self.contents.issuer.as_ref().map(|issuer| PrintableString(issuer.as_str())) |
| 119 | + } |
| 120 | + |
| 121 | + /// Paths to the recipient originating from publicly reachable nodes. Blinded paths provide |
| 122 | + /// recipient privacy by obfuscating its node id. |
| 123 | + pub fn paths(&self) -> &[BlindedPath] { |
| 124 | + self.contents.paths.as_ref().map(|paths| paths.as_slice()).unwrap_or(&[]) |
| 125 | + } |
| 126 | + |
| 127 | + /// The quantity of items supported. |
| 128 | + pub fn supported_quantity(&self) -> Quantity { |
| 129 | + match self.contents.quantity_max { |
| 130 | + Some(0) => Quantity::Unbounded, |
| 131 | + Some(n) => Quantity::Bounded(NonZeroU64::new(n).unwrap()), |
| 132 | + None => Quantity::Bounded(NonZeroU64::new(1).unwrap()), |
| 133 | + } |
| 134 | + } |
| 135 | + |
| 136 | + /// The public key used by the recipient to sign invoices. |
| 137 | + pub fn signing_pubkey(&self) -> PublicKey { |
| 138 | + self.contents.signing_pubkey.unwrap() |
| 139 | + } |
| 140 | +} |
| 141 | + |
| 142 | +/// The minimum amount required for an item in an [`Offer`], denominated in either bitcoin or |
| 143 | +/// another currency. |
| 144 | +#[derive(Clone, Debug)] |
| 145 | +pub enum Amount { |
| 146 | + /// An amount of bitcoin. |
| 147 | + Bitcoin { |
| 148 | + /// The amount in millisatoshi. |
| 149 | + amount_msats: u64, |
| 150 | + }, |
| 151 | + /// An amount of currency specified using ISO 4712. |
| 152 | + Currency { |
| 153 | + /// The currency that the amount is denominated in. |
| 154 | + iso4217_code: CurrencyCode, |
| 155 | + /// The amount in the currency unit adjusted by the ISO 4712 exponent (e.g., USD cents). |
| 156 | + amount: u64, |
| 157 | + }, |
| 158 | +} |
| 159 | + |
| 160 | +/// An ISO 4712 three-letter currency code (e.g., USD). |
| 161 | +pub type CurrencyCode = [u8; 3]; |
| 162 | + |
| 163 | +/// Quantity of items supported by an [`Offer`]. |
| 164 | +pub enum Quantity { |
| 165 | + /// Up to a specific number of items (inclusive). |
| 166 | + Bounded(NonZeroU64), |
| 167 | + /// One or more items. |
| 168 | + Unbounded, |
| 169 | +} |
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