git.bitcoin.ninja Git - rust-lightning/blob - lightning/src/offers/refund.rs

   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 refunds.
  11 //!
  12 //! A [`Refund`] is an "offer for money" and is typically constructed by a merchant and presented
  13 //! directly to the customer. The recipient responds with an `Invoice` to be paid.
  14 //!
  15 //! This is an [`InvoiceRequest`] produced *not* in response to an [`Offer`].
  16 //!
  17 //! [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
  18 //! [`Offer`]: crate::offers::offer::Offer
  19
  20 use bitcoin::blockdata::constants::ChainHash;
  21 use bitcoin::network::constants::Network;
  22 use bitcoin::secp256k1::PublicKey;
  23 use core::convert::TryFrom;
  24 use core::time::Duration;
  25 use crate::io;
  26 use crate::ln::features::InvoiceRequestFeatures;
  27 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
  28 use crate::offers::invoice_request::InvoiceRequestTlvStream;
  29 use crate::offers::offer::OfferTlvStream;
  30 use crate::offers::parse::{ParseError, ParsedMessage, SemanticError};
  31 use crate::offers::payer::{PayerContents, PayerTlvStream};
  32 use crate::onion_message::BlindedPath;
  33 use crate::util::ser::SeekReadable;
  34 use crate::util::string::PrintableString;
  35
  36 use crate::prelude::*;
  37
  38 #[cfg(feature = "std")]
  39 use std::time::SystemTime;
  40
  41 /// A `Refund` is a request to send an `Invoice` without a preceding [`Offer`].
  42 ///
  43 /// Typically, after an invoice is paid, the recipient may publish a refund allowing the sender to
  44 /// recoup their funds. A refund may be used more generally as an "offer for money", such as with a
  45 /// bitcoin ATM.
  46 ///
  47 /// [`Offer`]: crate::offers::offer::Offer
  48 #[derive(Clone, Debug)]
  49 pub struct Refund {
  50         bytes: Vec<u8>,
  51         contents: RefundContents,
  52 }
  53
  54 /// The contents of a [`Refund`], which may be shared with an `Invoice`.
  55 #[derive(Clone, Debug)]
  56 struct RefundContents {
  57         payer: PayerContents,
  58         // offer fields
  59         metadata: Option<Vec<u8>>,
  60         description: String,
  61         absolute_expiry: Option<Duration>,
  62         issuer: Option<String>,
  63         paths: Option<Vec<BlindedPath>>,
  64         // invoice_request fields
  65         chain: Option<ChainHash>,
  66         amount_msats: u64,
  67         features: InvoiceRequestFeatures,
  68         payer_id: PublicKey,
  69         payer_note: Option<String>,
  70 }
  71
  72 impl Refund {
  73         /// A complete description of the purpose of the refund. Intended to be displayed to the user
  74         /// but with the caveat that it has not been verified in any way.
  75         pub fn description(&self) -> PrintableString {
  76                 PrintableString(&self.contents.description)
  77         }
  78
  79         /// Duration since the Unix epoch when an invoice should no longer be sent.
  80         ///
  81         /// If `None`, the refund does not expire.
  82         pub fn absolute_expiry(&self) -> Option<Duration> {
  83                 self.contents.absolute_expiry
  84         }
  85
  86         /// Whether the refund has expired.
  87         #[cfg(feature = "std")]
  88         pub fn is_expired(&self) -> bool {
  89                 match self.absolute_expiry() {
  90                         Some(seconds_from_epoch) => match SystemTime::UNIX_EPOCH.elapsed() {
  91                                 Ok(elapsed) => elapsed > seconds_from_epoch,
  92                                 Err(_) => false,
  93                         },
  94                         None => false,
  95                 }
  96         }
  97
  98         /// The issuer of the refund, possibly beginning with `user@domain` or `domain`. Intended to be
  99         /// displayed to the user but with the caveat that it has not been verified in any way.
 100         pub fn issuer(&self) -> Option<PrintableString> {
 101                 self.contents.issuer.as_ref().map(|issuer| PrintableString(issuer.as_str()))
 102         }
 103
 104         /// Paths to the sender originating from publicly reachable nodes. Blinded paths provide sender
 105         /// privacy by obfuscating its node id.
 106         pub fn paths(&self) -> &[BlindedPath] {
 107                 self.contents.paths.as_ref().map(|paths| paths.as_slice()).unwrap_or(&[])
 108         }
 109
 110         /// An unpredictable series of bytes, typically containing information about the derivation of
 111         /// [`payer_id`].
 112         ///
 113         /// [`payer_id`]: Self::payer_id
 114         pub fn metadata(&self) -> &[u8] {
 115                 &self.contents.payer.0
 116         }
 117
 118         /// A chain that the refund is valid for.
 119         pub fn chain(&self) -> ChainHash {
 120                 self.contents.chain.unwrap_or_else(|| ChainHash::using_genesis_block(Network::Bitcoin))
 121         }
 122
 123         /// The amount to refund in msats (i.e., the minimum lightning-payable unit for [`chain`]).
 124         ///
 125         /// [`chain`]: Self::chain
 126         pub fn amount_msats(&self) -> u64 {
 127                 self.contents.amount_msats
 128         }
 129
 130         /// Features pertaining to requesting an invoice.
 131         pub fn features(&self) -> &InvoiceRequestFeatures {
 132                 &self.contents.features
 133         }
 134
 135         /// A possibly transient pubkey used to sign the refund.
 136         pub fn payer_id(&self) -> PublicKey {
 137                 self.contents.payer_id
 138         }
 139
 140         /// Payer provided note to include in the invoice.
 141         pub fn payer_note(&self) -> Option<PrintableString> {
 142                 self.contents.payer_note.as_ref().map(|payer_note| PrintableString(payer_note.as_str()))
 143         }
 144 }
 145
 146 type RefundTlvStream = (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream);
 147
 148 impl SeekReadable for RefundTlvStream {
 149         fn read<R: io::Read + io::Seek>(r: &mut R) -> Result<Self, DecodeError> {
 150                 let payer = SeekReadable::read(r)?;
 151                 let offer = SeekReadable::read(r)?;
 152                 let invoice_request = SeekReadable::read(r)?;
 153
 154                 Ok((payer, offer, invoice_request))
 155         }
 156 }
 157
 158 impl TryFrom<Vec<u8>> for Refund {
 159         type Error = ParseError;
 160
 161         fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
 162                 let refund = ParsedMessage::<RefundTlvStream>::try_from(bytes)?;
 163                 let ParsedMessage { bytes, tlv_stream } = refund;
 164                 let contents = RefundContents::try_from(tlv_stream)?;
 165
 166                 Ok(Refund { bytes, contents })
 167         }
 168 }
 169
 170 impl TryFrom<RefundTlvStream> for RefundContents {
 171         type Error = SemanticError;
 172
 173         fn try_from(tlv_stream: RefundTlvStream) -> Result<Self, Self::Error> {
 174                 let (
 175                         PayerTlvStream { metadata: payer_metadata },
 176                         OfferTlvStream {
 177                                 chains, metadata, currency, amount: offer_amount, description,
 178                                 features: offer_features, absolute_expiry, paths, issuer, quantity_max, node_id,
 179                         },
 180                         InvoiceRequestTlvStream { chain, amount, features, quantity, payer_id, payer_note },
 181                 ) = tlv_stream;
 182
 183                 let payer = match payer_metadata {
 184                         None => return Err(SemanticError::MissingPayerMetadata),
 185                         Some(metadata) => PayerContents(metadata),
 186                 };
 187
 188                 if chains.is_some() {
 189                         return Err(SemanticError::UnexpectedChain);
 190                 }
 191
 192                 if currency.is_some() || offer_amount.is_some() {
 193                         return Err(SemanticError::UnexpectedAmount);
 194                 }
 195
 196                 let description = match description {
 197                         None => return Err(SemanticError::MissingDescription),
 198                         Some(description) => description,
 199                 };
 200
 201                 if offer_features.is_some() {
 202                         return Err(SemanticError::UnexpectedFeatures);
 203                 }
 204
 205                 let absolute_expiry = absolute_expiry.map(Duration::from_secs);
 206
 207                 if quantity_max.is_some() {
 208                         return Err(SemanticError::UnexpectedQuantity);
 209                 }
 210
 211                 if node_id.is_some() {
 212                         return Err(SemanticError::UnexpectedSigningPubkey);
 213                 }
 214
 215                 let amount_msats = match amount {
 216                         None => return Err(SemanticError::MissingAmount),
 217                         Some(amount_msats) if amount_msats > MAX_VALUE_MSAT => {
 218                                 return Err(SemanticError::InvalidAmount);
 219                         },
 220                         Some(amount_msats) => amount_msats,
 221                 };
 222
 223                 let features = features.unwrap_or_else(InvoiceRequestFeatures::empty);
 224
 225                 // TODO: Check why this isn't in the spec.
 226                 if quantity.is_some() {
 227                         return Err(SemanticError::UnexpectedQuantity);
 228                 }
 229
 230                 let payer_id = match payer_id {
 231                         None => return Err(SemanticError::MissingPayerId),
 232                         Some(payer_id) => payer_id,
 233                 };
 234
 235                 // TODO: Should metadata be included?
 236                 Ok(RefundContents {
 237                         payer, metadata, description, absolute_expiry, issuer, paths, chain, amount_msats,
 238                         features, payer_id, payer_note,
 239                 })
 240         }
 241 }