_ 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::str::FromStr;
  25 use core::time::Duration;
  26 use crate::io;
  27 use crate::ln::features::InvoiceRequestFeatures;
  28 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
  29 use crate::offers::invoice_request::InvoiceRequestTlvStream;
  30 use crate::offers::offer::OfferTlvStream;
  31 use crate::offers::parse::{Bech32Encode, ParseError, ParsedMessage, SemanticError};
  32 use crate::offers::payer::{PayerContents, PayerTlvStream};
  33 use crate::onion_message::BlindedPath;
  34 use crate::util::ser::{SeekReadable, WithoutLength, Writeable, Writer};
  35 use crate::util::string::PrintableString;
  36
  37 use crate::prelude::*;
  38
  39 #[cfg(feature = "std")]
  40 use std::time::SystemTime;
  41
  42 /// A `Refund` is a request to send an `Invoice` without a preceding [`Offer`].
  43 ///
  44 /// Typically, after an invoice is paid, the recipient may publish a refund allowing the sender to
  45 /// recoup their funds. A refund may be used more generally as an "offer for money", such as with a
  46 /// bitcoin ATM.
  47 ///
  48 /// [`Offer`]: crate::offers::offer::Offer
  49 #[derive(Clone, Debug)]
  50 pub struct Refund {
  51         bytes: Vec<u8>,
  52         contents: RefundContents,
  53 }
  54
  55 /// The contents of a [`Refund`], which may be shared with an `Invoice`.
  56 #[derive(Clone, Debug)]
  57 struct RefundContents {
  58         payer: PayerContents,
  59         // offer fields
  60         metadata: Option<Vec<u8>>,
  61         description: String,
  62         absolute_expiry: Option<Duration>,
  63         issuer: Option<String>,
  64         paths: Option<Vec<BlindedPath>>,
  65         // invoice_request fields
  66         chain: Option<ChainHash>,
  67         amount_msats: u64,
  68         features: InvoiceRequestFeatures,
  69         payer_id: PublicKey,
  70         payer_note: Option<String>,
  71 }
  72
  73 impl Refund {
  74         /// A complete description of the purpose of the refund. Intended to be displayed to the user
  75         /// but with the caveat that it has not been verified in any way.
  76         pub fn description(&self) -> PrintableString {
  77                 PrintableString(&self.contents.description)
  78         }
  79
  80         /// Duration since the Unix epoch when an invoice should no longer be sent.
  81         ///
  82         /// If `None`, the refund does not expire.
  83         pub fn absolute_expiry(&self) -> Option<Duration> {
  84                 self.contents.absolute_expiry
  85         }
  86
  87         /// Whether the refund has expired.
  88         #[cfg(feature = "std")]
  89         pub fn is_expired(&self) -> bool {
  90                 match self.absolute_expiry() {
  91                         Some(seconds_from_epoch) => match SystemTime::UNIX_EPOCH.elapsed() {
  92                                 Ok(elapsed) => elapsed > seconds_from_epoch,
  93                                 Err(_) => false,
  94                         },
  95                         None => false,
  96                 }
  97         }
  98
  99         /// The issuer of the refund, possibly beginning with `user@domain` or `domain`. Intended to be
 100         /// displayed to the user but with the caveat that it has not been verified in any way.
 101         pub fn issuer(&self) -> Option<PrintableString> {
 102                 self.contents.issuer.as_ref().map(|issuer| PrintableString(issuer.as_str()))
 103         }
 104
 105         /// Paths to the sender originating from publicly reachable nodes. Blinded paths provide sender
 106         /// privacy by obfuscating its node id.
 107         pub fn paths(&self) -> &[BlindedPath] {
 108                 self.contents.paths.as_ref().map(|paths| paths.as_slice()).unwrap_or(&[])
 109         }
 110
 111         /// An unpredictable series of bytes, typically containing information about the derivation of
 112         /// [`payer_id`].
 113         ///
 114         /// [`payer_id`]: Self::payer_id
 115         pub fn metadata(&self) -> &[u8] {
 116                 &self.contents.payer.0
 117         }
 118
 119         /// A chain that the refund is valid for.
 120         pub fn chain(&self) -> ChainHash {
 121                 self.contents.chain.unwrap_or_else(|| ChainHash::using_genesis_block(Network::Bitcoin))
 122         }
 123
 124         /// The amount to refund in msats (i.e., the minimum lightning-payable unit for [`chain`]).
 125         ///
 126         /// [`chain`]: Self::chain
 127         pub fn amount_msats(&self) -> u64 {
 128                 self.contents.amount_msats
 129         }
 130
 131         /// Features pertaining to requesting an invoice.
 132         pub fn features(&self) -> &InvoiceRequestFeatures {
 133                 &self.contents.features
 134         }
 135
 136         /// A possibly transient pubkey used to sign the refund.
 137         pub fn payer_id(&self) -> PublicKey {
 138                 self.contents.payer_id
 139         }
 140
 141         /// Payer provided note to include in the invoice.
 142         pub fn payer_note(&self) -> Option<PrintableString> {
 143                 self.contents.payer_note.as_ref().map(|payer_note| PrintableString(payer_note.as_str()))
 144         }
 145 }
 146
 147 impl AsRef<[u8]> for Refund {
 148         fn as_ref(&self) -> &[u8] {
 149                 &self.bytes
 150         }
 151 }
 152
 153 impl Writeable for Refund {
 154         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 155                 WithoutLength(&self.bytes).write(writer)
 156         }
 157 }
 158
 159 type RefundTlvStream = (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream);
 160
 161 impl SeekReadable for RefundTlvStream {
 162         fn read<R: io::Read + io::Seek>(r: &mut R) -> Result<Self, DecodeError> {
 163                 let payer = SeekReadable::read(r)?;
 164                 let offer = SeekReadable::read(r)?;
 165                 let invoice_request = SeekReadable::read(r)?;
 166
 167                 Ok((payer, offer, invoice_request))
 168         }
 169 }
 170
 171 impl Bech32Encode for Refund {
 172         const BECH32_HRP: &'static str = "lnr";
 173 }
 174
 175 impl FromStr for Refund {
 176         type Err = ParseError;
 177
 178         fn from_str(s: &str) -> Result<Self, <Self as FromStr>::Err> {
 179                 Refund::from_bech32_str(s)
 180         }
 181 }
 182
 183 impl TryFrom<Vec<u8>> for Refund {
 184         type Error = ParseError;
 185
 186         fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
 187                 let refund = ParsedMessage::<RefundTlvStream>::try_from(bytes)?;
 188                 let ParsedMessage { bytes, tlv_stream } = refund;
 189                 let contents = RefundContents::try_from(tlv_stream)?;
 190
 191                 Ok(Refund { bytes, contents })
 192         }
 193 }
 194
 195 impl TryFrom<RefundTlvStream> for RefundContents {
 196         type Error = SemanticError;
 197
 198         fn try_from(tlv_stream: RefundTlvStream) -> Result<Self, Self::Error> {
 199                 let (
 200                         PayerTlvStream { metadata: payer_metadata },
 201                         OfferTlvStream {
 202                                 chains, metadata, currency, amount: offer_amount, description,
 203                                 features: offer_features, absolute_expiry, paths, issuer, quantity_max, node_id,
 204                         },
 205                         InvoiceRequestTlvStream { chain, amount, features, quantity, payer_id, payer_note },
 206                 ) = tlv_stream;
 207
 208                 let payer = match payer_metadata {
 209                         None => return Err(SemanticError::MissingPayerMetadata),
 210                         Some(metadata) => PayerContents(metadata),
 211                 };
 212
 213                 if chains.is_some() {
 214                         return Err(SemanticError::UnexpectedChain);
 215                 }
 216
 217                 if currency.is_some() || offer_amount.is_some() {
 218                         return Err(SemanticError::UnexpectedAmount);
 219                 }
 220
 221                 let description = match description {
 222                         None => return Err(SemanticError::MissingDescription),
 223                         Some(description) => description,
 224                 };
 225
 226                 if offer_features.is_some() {
 227                         return Err(SemanticError::UnexpectedFeatures);
 228                 }
 229
 230                 let absolute_expiry = absolute_expiry.map(Duration::from_secs);
 231
 232                 if quantity_max.is_some() {
 233                         return Err(SemanticError::UnexpectedQuantity);
 234                 }
 235
 236                 if node_id.is_some() {
 237                         return Err(SemanticError::UnexpectedSigningPubkey);
 238                 }
 239
 240                 let amount_msats = match amount {
 241                         None => return Err(SemanticError::MissingAmount),
 242                         Some(amount_msats) if amount_msats > MAX_VALUE_MSAT => {
 243                                 return Err(SemanticError::InvalidAmount);
 244                         },
 245                         Some(amount_msats) => amount_msats,
 246                 };
 247
 248                 let features = features.unwrap_or_else(InvoiceRequestFeatures::empty);
 249
 250                 // TODO: Check why this isn't in the spec.
 251                 if quantity.is_some() {
 252                         return Err(SemanticError::UnexpectedQuantity);
 253                 }
 254
 255                 let payer_id = match payer_id {
 256                         None => return Err(SemanticError::MissingPayerId),
 257                         Some(payer_id) => payer_id,
 258                 };
 259
 260                 // TODO: Should metadata be included?
 261                 Ok(RefundContents {
 262                         payer, metadata, description, absolute_expiry, issuer, paths, chain, amount_msats,
 263                         features, payer_id, payer_note,
 264                 })
 265         }
 266 }
 267
 268 impl core::fmt::Display for Refund {
 269         fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
 270                 self.fmt_bech32_str(f)
 271         }
 272 }