]> git.bitcoin.ninja Git - rust-lightning/blob - lightning/src/offers/refund.rs
Merge pull request #1908 from jkczyz/2022-11-refund
[rust-lightning] / 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 //! ```ignore
21 //! extern crate bitcoin;
22 //! extern crate core;
23 //! extern crate lightning;
24 //!
25 //! use core::convert::TryFrom;
26 //! use core::time::Duration;
27 //!
28 //! use bitcoin::network::constants::Network;
29 //! use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
30 //! use lightning::offers::parse::ParseError;
31 //! use lightning::offers::refund::{Refund, RefundBuilder};
32 //! use lightning::util::ser::{Readable, Writeable};
33 //!
34 //! # use lightning::onion_message::BlindedPath;
35 //! # #[cfg(feature = "std")]
36 //! # use std::time::SystemTime;
37 //! #
38 //! # fn create_blinded_path() -> BlindedPath { unimplemented!() }
39 //! # fn create_another_blinded_path() -> BlindedPath { unimplemented!() }
40 //! #
41 //! # #[cfg(feature = "std")]
42 //! # fn build() -> Result<(), ParseError> {
43 //! let secp_ctx = Secp256k1::new();
44 //! let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
45 //! let pubkey = PublicKey::from(keys);
46 //!
47 //! let expiration = SystemTime::now() + Duration::from_secs(24 * 60 * 60);
48 //! let refund = RefundBuilder::new("coffee, large".to_string(), vec![1; 32], pubkey, 20_000)?
49 //!     .absolute_expiry(expiration.duration_since(SystemTime::UNIX_EPOCH).unwrap())
50 //!     .issuer("Foo Bar".to_string())
51 //!     .path(create_blinded_path())
52 //!     .path(create_another_blinded_path())
53 //!     .chain(Network::Bitcoin)
54 //!     .payer_note("refund for order #12345".to_string())
55 //!     .build()?;
56 //!
57 //! // Encode as a bech32 string for use in a QR code.
58 //! let encoded_refund = refund.to_string();
59 //!
60 //! // Parse from a bech32 string after scanning from a QR code.
61 //! let refund = encoded_refund.parse::<Refund>()?;
62 //!
63 //! // Encode refund as raw bytes.
64 //! let mut bytes = Vec::new();
65 //! refund.write(&mut bytes).unwrap();
66 //!
67 //! // Decode raw bytes into an refund.
68 //! let refund = Refund::try_from(bytes)?;
69 //! # Ok(())
70 //! # }
71 //! ```
72
73 use bitcoin::blockdata::constants::ChainHash;
74 use bitcoin::network::constants::Network;
75 use bitcoin::secp256k1::PublicKey;
76 use core::convert::TryFrom;
77 use core::str::FromStr;
78 use core::time::Duration;
79 use crate::io;
80 use crate::ln::features::InvoiceRequestFeatures;
81 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
82 use crate::offers::invoice_request::{InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef};
83 use crate::offers::offer::{OfferTlvStream, OfferTlvStreamRef};
84 use crate::offers::parse::{Bech32Encode, ParseError, ParsedMessage, SemanticError};
85 use crate::offers::payer::{PayerContents, PayerTlvStream, PayerTlvStreamRef};
86 use crate::onion_message::BlindedPath;
87 use crate::util::ser::{SeekReadable, WithoutLength, Writeable, Writer};
88 use crate::util::string::PrintableString;
89
90 use crate::prelude::*;
91
92 #[cfg(feature = "std")]
93 use std::time::SystemTime;
94
95 /// Builds a [`Refund`] for the "offer for money" flow.
96 ///
97 /// See [module-level documentation] for usage.
98 ///
99 /// [module-level documentation]: self
100 pub struct RefundBuilder {
101         refund: RefundContents,
102 }
103
104 impl RefundBuilder {
105         /// Creates a new builder for a refund using the [`Refund::payer_id`] for signing invoices. Use
106         /// a different pubkey per refund to avoid correlating refunds.
107         ///
108         /// Additionally, sets the required [`Refund::description`], [`Refund::metadata`], and
109         /// [`Refund::amount_msats`].
110         pub fn new(
111                 description: String, metadata: Vec<u8>, payer_id: PublicKey, amount_msats: u64
112         ) -> Result<Self, SemanticError> {
113                 if amount_msats > MAX_VALUE_MSAT {
114                         return Err(SemanticError::InvalidAmount);
115                 }
116
117                 let refund = RefundContents {
118                         payer: PayerContents(metadata), metadata: None, description, absolute_expiry: None,
119                         issuer: None, paths: None, chain: None, amount_msats,
120                         features: InvoiceRequestFeatures::empty(), payer_id, payer_note: None,
121                 };
122
123                 Ok(RefundBuilder { refund })
124         }
125
126         /// Sets the [`Refund::absolute_expiry`] as seconds since the Unix epoch. Any expiry that has
127         /// already passed is valid and can be checked for using [`Refund::is_expired`].
128         ///
129         /// Successive calls to this method will override the previous setting.
130         pub fn absolute_expiry(mut self, absolute_expiry: Duration) -> Self {
131                 self.refund.absolute_expiry = Some(absolute_expiry);
132                 self
133         }
134
135         /// Sets the [`Refund::issuer`].
136         ///
137         /// Successive calls to this method will override the previous setting.
138         pub fn issuer(mut self, issuer: String) -> Self {
139                 self.refund.issuer = Some(issuer);
140                 self
141         }
142
143         /// Adds a blinded path to [`Refund::paths`]. Must include at least one path if only connected
144         /// by private channels or if [`Refund::payer_id`] is not a public node id.
145         ///
146         /// Successive calls to this method will add another blinded path. Caller is responsible for not
147         /// adding duplicate paths.
148         pub fn path(mut self, path: BlindedPath) -> Self {
149                 self.refund.paths.get_or_insert_with(Vec::new).push(path);
150                 self
151         }
152
153         /// Sets the [`Refund::chain`] of the given [`Network`] for paying an invoice. If not
154         /// called, [`Network::Bitcoin`] is assumed.
155         ///
156         /// Successive calls to this method will override the previous setting.
157         pub fn chain(mut self, network: Network) -> Self {
158                 self.refund.chain = Some(ChainHash::using_genesis_block(network));
159                 self
160         }
161
162         /// Sets the [`Refund::payer_note`].
163         ///
164         /// Successive calls to this method will override the previous setting.
165         pub fn payer_note(mut self, payer_note: String) -> Self {
166                 self.refund.payer_note = Some(payer_note);
167                 self
168         }
169
170         /// Builds a [`Refund`] after checking for valid semantics.
171         pub fn build(mut self) -> Result<Refund, SemanticError> {
172                 if self.refund.chain() == self.refund.implied_chain() {
173                         self.refund.chain = None;
174                 }
175
176                 let mut bytes = Vec::new();
177                 self.refund.write(&mut bytes).unwrap();
178
179                 Ok(Refund {
180                         bytes,
181                         contents: self.refund,
182                 })
183         }
184 }
185
186 #[cfg(test)]
187 impl RefundBuilder {
188         fn features_unchecked(mut self, features: InvoiceRequestFeatures) -> Self {
189                 self.refund.features = features;
190                 self
191         }
192 }
193
194 /// A `Refund` is a request to send an `Invoice` without a preceding [`Offer`].
195 ///
196 /// Typically, after an invoice is paid, the recipient may publish a refund allowing the sender to
197 /// recoup their funds. A refund may be used more generally as an "offer for money", such as with a
198 /// bitcoin ATM.
199 ///
200 /// [`Offer`]: crate::offers::offer::Offer
201 #[derive(Clone, Debug)]
202 pub struct Refund {
203         bytes: Vec<u8>,
204         contents: RefundContents,
205 }
206
207 /// The contents of a [`Refund`], which may be shared with an `Invoice`.
208 #[derive(Clone, Debug)]
209 struct RefundContents {
210         payer: PayerContents,
211         // offer fields
212         metadata: Option<Vec<u8>>,
213         description: String,
214         absolute_expiry: Option<Duration>,
215         issuer: Option<String>,
216         paths: Option<Vec<BlindedPath>>,
217         // invoice_request fields
218         chain: Option<ChainHash>,
219         amount_msats: u64,
220         features: InvoiceRequestFeatures,
221         payer_id: PublicKey,
222         payer_note: Option<String>,
223 }
224
225 impl Refund {
226         /// A complete description of the purpose of the refund. Intended to be displayed to the user
227         /// but with the caveat that it has not been verified in any way.
228         pub fn description(&self) -> PrintableString {
229                 PrintableString(&self.contents.description)
230         }
231
232         /// Duration since the Unix epoch when an invoice should no longer be sent.
233         ///
234         /// If `None`, the refund does not expire.
235         pub fn absolute_expiry(&self) -> Option<Duration> {
236                 self.contents.absolute_expiry
237         }
238
239         /// Whether the refund has expired.
240         #[cfg(feature = "std")]
241         pub fn is_expired(&self) -> bool {
242                 match self.absolute_expiry() {
243                         Some(seconds_from_epoch) => match SystemTime::UNIX_EPOCH.elapsed() {
244                                 Ok(elapsed) => elapsed > seconds_from_epoch,
245                                 Err(_) => false,
246                         },
247                         None => false,
248                 }
249         }
250
251         /// The issuer of the refund, possibly beginning with `user@domain` or `domain`. Intended to be
252         /// displayed to the user but with the caveat that it has not been verified in any way.
253         pub fn issuer(&self) -> Option<PrintableString> {
254                 self.contents.issuer.as_ref().map(|issuer| PrintableString(issuer.as_str()))
255         }
256
257         /// Paths to the sender originating from publicly reachable nodes. Blinded paths provide sender
258         /// privacy by obfuscating its node id.
259         pub fn paths(&self) -> &[BlindedPath] {
260                 self.contents.paths.as_ref().map(|paths| paths.as_slice()).unwrap_or(&[])
261         }
262
263         /// An unpredictable series of bytes, typically containing information about the derivation of
264         /// [`payer_id`].
265         ///
266         /// [`payer_id`]: Self::payer_id
267         pub fn metadata(&self) -> &[u8] {
268                 &self.contents.payer.0
269         }
270
271         /// A chain that the refund is valid for.
272         pub fn chain(&self) -> ChainHash {
273                 self.contents.chain.unwrap_or_else(|| self.contents.implied_chain())
274         }
275
276         /// The amount to refund in msats (i.e., the minimum lightning-payable unit for [`chain`]).
277         ///
278         /// [`chain`]: Self::chain
279         pub fn amount_msats(&self) -> u64 {
280                 self.contents.amount_msats
281         }
282
283         /// Features pertaining to requesting an invoice.
284         pub fn features(&self) -> &InvoiceRequestFeatures {
285                 &self.contents.features
286         }
287
288         /// A possibly transient pubkey used to sign the refund.
289         pub fn payer_id(&self) -> PublicKey {
290                 self.contents.payer_id
291         }
292
293         /// Payer provided note to include in the invoice.
294         pub fn payer_note(&self) -> Option<PrintableString> {
295                 self.contents.payer_note.as_ref().map(|payer_note| PrintableString(payer_note.as_str()))
296         }
297
298         #[cfg(test)]
299         fn as_tlv_stream(&self) -> RefundTlvStreamRef {
300                 self.contents.as_tlv_stream()
301         }
302 }
303
304 impl AsRef<[u8]> for Refund {
305         fn as_ref(&self) -> &[u8] {
306                 &self.bytes
307         }
308 }
309
310 impl RefundContents {
311         fn chain(&self) -> ChainHash {
312                 self.chain.unwrap_or_else(|| self.implied_chain())
313         }
314
315         pub fn implied_chain(&self) -> ChainHash {
316                 ChainHash::using_genesis_block(Network::Bitcoin)
317         }
318
319         pub(super) fn as_tlv_stream(&self) -> RefundTlvStreamRef {
320                 let payer = PayerTlvStreamRef {
321                         metadata: Some(&self.payer.0),
322                 };
323
324                 let offer = OfferTlvStreamRef {
325                         chains: None,
326                         metadata: self.metadata.as_ref(),
327                         currency: None,
328                         amount: None,
329                         description: Some(&self.description),
330                         features: None,
331                         absolute_expiry: self.absolute_expiry.map(|duration| duration.as_secs()),
332                         paths: self.paths.as_ref(),
333                         issuer: self.issuer.as_ref(),
334                         quantity_max: None,
335                         node_id: None,
336                 };
337
338                 let features = {
339                         if self.features == InvoiceRequestFeatures::empty() { None }
340                         else { Some(&self.features) }
341                 };
342
343                 let invoice_request = InvoiceRequestTlvStreamRef {
344                         chain: self.chain.as_ref(),
345                         amount: Some(self.amount_msats),
346                         features,
347                         quantity: None,
348                         payer_id: Some(&self.payer_id),
349                         payer_note: self.payer_note.as_ref(),
350                 };
351
352                 (payer, offer, invoice_request)
353         }
354 }
355
356 impl Writeable for Refund {
357         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
358                 WithoutLength(&self.bytes).write(writer)
359         }
360 }
361
362 impl Writeable for RefundContents {
363         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
364                 self.as_tlv_stream().write(writer)
365         }
366 }
367
368 type RefundTlvStream = (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream);
369
370 type RefundTlvStreamRef<'a> = (
371         PayerTlvStreamRef<'a>,
372         OfferTlvStreamRef<'a>,
373         InvoiceRequestTlvStreamRef<'a>,
374 );
375
376 impl SeekReadable for RefundTlvStream {
377         fn read<R: io::Read + io::Seek>(r: &mut R) -> Result<Self, DecodeError> {
378                 let payer = SeekReadable::read(r)?;
379                 let offer = SeekReadable::read(r)?;
380                 let invoice_request = SeekReadable::read(r)?;
381
382                 Ok((payer, offer, invoice_request))
383         }
384 }
385
386 impl Bech32Encode for Refund {
387         const BECH32_HRP: &'static str = "lnr";
388 }
389
390 impl FromStr for Refund {
391         type Err = ParseError;
392
393         fn from_str(s: &str) -> Result<Self, <Self as FromStr>::Err> {
394                 Refund::from_bech32_str(s)
395         }
396 }
397
398 impl TryFrom<Vec<u8>> for Refund {
399         type Error = ParseError;
400
401         fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
402                 let refund = ParsedMessage::<RefundTlvStream>::try_from(bytes)?;
403                 let ParsedMessage { bytes, tlv_stream } = refund;
404                 let contents = RefundContents::try_from(tlv_stream)?;
405
406                 Ok(Refund { bytes, contents })
407         }
408 }
409
410 impl TryFrom<RefundTlvStream> for RefundContents {
411         type Error = SemanticError;
412
413         fn try_from(tlv_stream: RefundTlvStream) -> Result<Self, Self::Error> {
414                 let (
415                         PayerTlvStream { metadata: payer_metadata },
416                         OfferTlvStream {
417                                 chains, metadata, currency, amount: offer_amount, description,
418                                 features: offer_features, absolute_expiry, paths, issuer, quantity_max, node_id,
419                         },
420                         InvoiceRequestTlvStream { chain, amount, features, quantity, payer_id, payer_note },
421                 ) = tlv_stream;
422
423                 let payer = match payer_metadata {
424                         None => return Err(SemanticError::MissingPayerMetadata),
425                         Some(metadata) => PayerContents(metadata),
426                 };
427
428                 if chains.is_some() {
429                         return Err(SemanticError::UnexpectedChain);
430                 }
431
432                 if currency.is_some() || offer_amount.is_some() {
433                         return Err(SemanticError::UnexpectedAmount);
434                 }
435
436                 let description = match description {
437                         None => return Err(SemanticError::MissingDescription),
438                         Some(description) => description,
439                 };
440
441                 if offer_features.is_some() {
442                         return Err(SemanticError::UnexpectedFeatures);
443                 }
444
445                 let absolute_expiry = absolute_expiry.map(Duration::from_secs);
446
447                 if quantity_max.is_some() {
448                         return Err(SemanticError::UnexpectedQuantity);
449                 }
450
451                 if node_id.is_some() {
452                         return Err(SemanticError::UnexpectedSigningPubkey);
453                 }
454
455                 let amount_msats = match amount {
456                         None => return Err(SemanticError::MissingAmount),
457                         Some(amount_msats) if amount_msats > MAX_VALUE_MSAT => {
458                                 return Err(SemanticError::InvalidAmount);
459                         },
460                         Some(amount_msats) => amount_msats,
461                 };
462
463                 let features = features.unwrap_or_else(InvoiceRequestFeatures::empty);
464
465                 // TODO: Check why this isn't in the spec.
466                 if quantity.is_some() {
467                         return Err(SemanticError::UnexpectedQuantity);
468                 }
469
470                 let payer_id = match payer_id {
471                         None => return Err(SemanticError::MissingPayerId),
472                         Some(payer_id) => payer_id,
473                 };
474
475                 // TODO: Should metadata be included?
476                 Ok(RefundContents {
477                         payer, metadata, description, absolute_expiry, issuer, paths, chain, amount_msats,
478                         features, payer_id, payer_note,
479                 })
480         }
481 }
482
483 impl core::fmt::Display for Refund {
484         fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
485                 self.fmt_bech32_str(f)
486         }
487 }
488
489 #[cfg(test)]
490 mod tests {
491         use super::{Refund, RefundBuilder, RefundTlvStreamRef};
492
493         use bitcoin::blockdata::constants::ChainHash;
494         use bitcoin::network::constants::Network;
495         use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
496         use core::convert::TryFrom;
497         use core::time::Duration;
498         use crate::ln::features::{InvoiceRequestFeatures, OfferFeatures};
499         use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
500         use crate::offers::invoice_request::InvoiceRequestTlvStreamRef;
501         use crate::offers::offer::OfferTlvStreamRef;
502         use crate::offers::parse::{ParseError, SemanticError};
503         use crate::offers::payer::PayerTlvStreamRef;
504         use crate::onion_message::{BlindedHop, BlindedPath};
505         use crate::util::ser::{BigSize, Writeable};
506         use crate::util::string::PrintableString;
507
508         fn payer_pubkey() -> PublicKey {
509                 let secp_ctx = Secp256k1::new();
510                 KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap()).public_key()
511         }
512
513         fn pubkey(byte: u8) -> PublicKey {
514                 let secp_ctx = Secp256k1::new();
515                 PublicKey::from_secret_key(&secp_ctx, &privkey(byte))
516         }
517
518         fn privkey(byte: u8) -> SecretKey {
519                 SecretKey::from_slice(&[byte; 32]).unwrap()
520         }
521
522         trait ToBytes {
523                 fn to_bytes(&self) -> Vec<u8>;
524         }
525
526         impl<'a> ToBytes for RefundTlvStreamRef<'a> {
527                 fn to_bytes(&self) -> Vec<u8> {
528                         let mut buffer = Vec::new();
529                         self.write(&mut buffer).unwrap();
530                         buffer
531                 }
532         }
533
534         #[test]
535         fn builds_refund_with_defaults() {
536                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
537                         .build().unwrap();
538
539                 let mut buffer = Vec::new();
540                 refund.write(&mut buffer).unwrap();
541
542                 assert_eq!(refund.bytes, buffer.as_slice());
543                 assert_eq!(refund.metadata(), &[1; 32]);
544                 assert_eq!(refund.description(), PrintableString("foo"));
545                 assert_eq!(refund.absolute_expiry(), None);
546                 #[cfg(feature = "std")]
547                 assert!(!refund.is_expired());
548                 assert_eq!(refund.paths(), &[]);
549                 assert_eq!(refund.issuer(), None);
550                 assert_eq!(refund.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
551                 assert_eq!(refund.amount_msats(), 1000);
552                 assert_eq!(refund.features(), &InvoiceRequestFeatures::empty());
553                 assert_eq!(refund.payer_id(), payer_pubkey());
554                 assert_eq!(refund.payer_note(), None);
555
556                 assert_eq!(
557                         refund.as_tlv_stream(),
558                         (
559                                 PayerTlvStreamRef { metadata: Some(&vec![1; 32]) },
560                                 OfferTlvStreamRef {
561                                         chains: None,
562                                         metadata: None,
563                                         currency: None,
564                                         amount: None,
565                                         description: Some(&String::from("foo")),
566                                         features: None,
567                                         absolute_expiry: None,
568                                         paths: None,
569                                         issuer: None,
570                                         quantity_max: None,
571                                         node_id: None,
572                                 },
573                                 InvoiceRequestTlvStreamRef {
574                                         chain: None,
575                                         amount: Some(1000),
576                                         features: None,
577                                         quantity: None,
578                                         payer_id: Some(&payer_pubkey()),
579                                         payer_note: None,
580                                 },
581                         ),
582                 );
583
584                 if let Err(e) = Refund::try_from(buffer) {
585                         panic!("error parsing refund: {:?}", e);
586                 }
587         }
588
589         #[test]
590         fn fails_building_refund_with_invalid_amount() {
591                 match RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), MAX_VALUE_MSAT + 1) {
592                         Ok(_) => panic!("expected error"),
593                         Err(e) => assert_eq!(e, SemanticError::InvalidAmount),
594                 }
595         }
596
597         #[test]
598         fn builds_refund_with_absolute_expiry() {
599                 let future_expiry = Duration::from_secs(u64::max_value());
600                 let past_expiry = Duration::from_secs(0);
601
602                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
603                         .absolute_expiry(future_expiry)
604                         .build()
605                         .unwrap();
606                 let (_, tlv_stream, _) = refund.as_tlv_stream();
607                 #[cfg(feature = "std")]
608                 assert!(!refund.is_expired());
609                 assert_eq!(refund.absolute_expiry(), Some(future_expiry));
610                 assert_eq!(tlv_stream.absolute_expiry, Some(future_expiry.as_secs()));
611
612                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
613                         .absolute_expiry(future_expiry)
614                         .absolute_expiry(past_expiry)
615                         .build()
616                         .unwrap();
617                 let (_, tlv_stream, _) = refund.as_tlv_stream();
618                 #[cfg(feature = "std")]
619                 assert!(refund.is_expired());
620                 assert_eq!(refund.absolute_expiry(), Some(past_expiry));
621                 assert_eq!(tlv_stream.absolute_expiry, Some(past_expiry.as_secs()));
622         }
623
624         #[test]
625         fn builds_refund_with_paths() {
626                 let paths = vec![
627                         BlindedPath {
628                                 introduction_node_id: pubkey(40),
629                                 blinding_point: pubkey(41),
630                                 blinded_hops: vec![
631                                         BlindedHop { blinded_node_id: pubkey(43), encrypted_payload: vec![0; 43] },
632                                         BlindedHop { blinded_node_id: pubkey(44), encrypted_payload: vec![0; 44] },
633                                 ],
634                         },
635                         BlindedPath {
636                                 introduction_node_id: pubkey(40),
637                                 blinding_point: pubkey(41),
638                                 blinded_hops: vec![
639                                         BlindedHop { blinded_node_id: pubkey(45), encrypted_payload: vec![0; 45] },
640                                         BlindedHop { blinded_node_id: pubkey(46), encrypted_payload: vec![0; 46] },
641                                 ],
642                         },
643                 ];
644
645                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
646                         .path(paths[0].clone())
647                         .path(paths[1].clone())
648                         .build()
649                         .unwrap();
650                 let (_, offer_tlv_stream, invoice_request_tlv_stream) = refund.as_tlv_stream();
651                 assert_eq!(refund.paths(), paths.as_slice());
652                 assert_eq!(refund.payer_id(), pubkey(42));
653                 assert_ne!(pubkey(42), pubkey(44));
654                 assert_eq!(offer_tlv_stream.paths, Some(&paths));
655                 assert_eq!(invoice_request_tlv_stream.payer_id, Some(&pubkey(42)));
656         }
657
658         #[test]
659         fn builds_refund_with_issuer() {
660                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
661                         .issuer("bar".into())
662                         .build()
663                         .unwrap();
664                 let (_, tlv_stream, _) = refund.as_tlv_stream();
665                 assert_eq!(refund.issuer(), Some(PrintableString("bar")));
666                 assert_eq!(tlv_stream.issuer, Some(&String::from("bar")));
667
668                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
669                         .issuer("bar".into())
670                         .issuer("baz".into())
671                         .build()
672                         .unwrap();
673                 let (_, tlv_stream, _) = refund.as_tlv_stream();
674                 assert_eq!(refund.issuer(), Some(PrintableString("baz")));
675                 assert_eq!(tlv_stream.issuer, Some(&String::from("baz")));
676         }
677
678         #[test]
679         fn builds_refund_with_chain() {
680                 let mainnet = ChainHash::using_genesis_block(Network::Bitcoin);
681                 let testnet = ChainHash::using_genesis_block(Network::Testnet);
682
683                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
684                         .chain(Network::Bitcoin)
685                         .build().unwrap();
686                 let (_, _, tlv_stream) = refund.as_tlv_stream();
687                 assert_eq!(refund.chain(), mainnet);
688                 assert_eq!(tlv_stream.chain, None);
689
690                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
691                         .chain(Network::Testnet)
692                         .build().unwrap();
693                 let (_, _, tlv_stream) = refund.as_tlv_stream();
694                 assert_eq!(refund.chain(), testnet);
695                 assert_eq!(tlv_stream.chain, Some(&testnet));
696
697                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
698                         .chain(Network::Regtest)
699                         .chain(Network::Testnet)
700                         .build().unwrap();
701                 let (_, _, tlv_stream) = refund.as_tlv_stream();
702                 assert_eq!(refund.chain(), testnet);
703                 assert_eq!(tlv_stream.chain, Some(&testnet));
704         }
705
706         #[test]
707         fn builds_refund_with_payer_note() {
708                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
709                         .payer_note("bar".into())
710                         .build().unwrap();
711                 let (_, _, tlv_stream) = refund.as_tlv_stream();
712                 assert_eq!(refund.payer_note(), Some(PrintableString("bar")));
713                 assert_eq!(tlv_stream.payer_note, Some(&String::from("bar")));
714
715                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
716                         .payer_note("bar".into())
717                         .payer_note("baz".into())
718                         .build().unwrap();
719                 let (_, _, tlv_stream) = refund.as_tlv_stream();
720                 assert_eq!(refund.payer_note(), Some(PrintableString("baz")));
721                 assert_eq!(tlv_stream.payer_note, Some(&String::from("baz")));
722         }
723
724         #[test]
725         fn parses_refund_with_metadata() {
726                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
727                         .build().unwrap();
728                 if let Err(e) = refund.to_string().parse::<Refund>() {
729                         panic!("error parsing refund: {:?}", e);
730                 }
731
732                 let mut tlv_stream = refund.as_tlv_stream();
733                 tlv_stream.0.metadata = None;
734
735                 match Refund::try_from(tlv_stream.to_bytes()) {
736                         Ok(_) => panic!("expected error"),
737                         Err(e) => {
738                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::MissingPayerMetadata));
739                         },
740                 }
741         }
742
743         #[test]
744         fn parses_refund_with_description() {
745                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
746                         .build().unwrap();
747                 if let Err(e) = refund.to_string().parse::<Refund>() {
748                         panic!("error parsing refund: {:?}", e);
749                 }
750
751                 let mut tlv_stream = refund.as_tlv_stream();
752                 tlv_stream.1.description = None;
753
754                 match Refund::try_from(tlv_stream.to_bytes()) {
755                         Ok(_) => panic!("expected error"),
756                         Err(e) => {
757                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::MissingDescription));
758                         },
759                 }
760         }
761
762         #[test]
763         fn parses_refund_with_amount() {
764                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
765                         .build().unwrap();
766                 if let Err(e) = refund.to_string().parse::<Refund>() {
767                         panic!("error parsing refund: {:?}", e);
768                 }
769
770                 let mut tlv_stream = refund.as_tlv_stream();
771                 tlv_stream.2.amount = None;
772
773                 match Refund::try_from(tlv_stream.to_bytes()) {
774                         Ok(_) => panic!("expected error"),
775                         Err(e) => {
776                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::MissingAmount));
777                         },
778                 }
779
780                 let mut tlv_stream = refund.as_tlv_stream();
781                 tlv_stream.2.amount = Some(MAX_VALUE_MSAT + 1);
782
783                 match Refund::try_from(tlv_stream.to_bytes()) {
784                         Ok(_) => panic!("expected error"),
785                         Err(e) => {
786                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::InvalidAmount));
787                         },
788                 }
789         }
790
791         #[test]
792         fn parses_refund_with_payer_id() {
793                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
794                         .build().unwrap();
795                 if let Err(e) = refund.to_string().parse::<Refund>() {
796                         panic!("error parsing refund: {:?}", e);
797                 }
798
799                 let mut tlv_stream = refund.as_tlv_stream();
800                 tlv_stream.2.payer_id = None;
801
802                 match Refund::try_from(tlv_stream.to_bytes()) {
803                         Ok(_) => panic!("expected error"),
804                         Err(e) => {
805                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::MissingPayerId));
806                         },
807                 }
808         }
809
810         #[test]
811         fn parses_refund_with_optional_fields() {
812                 let past_expiry = Duration::from_secs(0);
813                 let paths = vec![
814                         BlindedPath {
815                                 introduction_node_id: pubkey(40),
816                                 blinding_point: pubkey(41),
817                                 blinded_hops: vec![
818                                         BlindedHop { blinded_node_id: pubkey(43), encrypted_payload: vec![0; 43] },
819                                         BlindedHop { blinded_node_id: pubkey(44), encrypted_payload: vec![0; 44] },
820                                 ],
821                         },
822                         BlindedPath {
823                                 introduction_node_id: pubkey(40),
824                                 blinding_point: pubkey(41),
825                                 blinded_hops: vec![
826                                         BlindedHop { blinded_node_id: pubkey(45), encrypted_payload: vec![0; 45] },
827                                         BlindedHop { blinded_node_id: pubkey(46), encrypted_payload: vec![0; 46] },
828                                 ],
829                         },
830                 ];
831
832                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
833                         .absolute_expiry(past_expiry)
834                         .issuer("bar".into())
835                         .path(paths[0].clone())
836                         .path(paths[1].clone())
837                         .chain(Network::Testnet)
838                         .features_unchecked(InvoiceRequestFeatures::unknown())
839                         .payer_note("baz".into())
840                         .build()
841                         .unwrap();
842                 match refund.to_string().parse::<Refund>() {
843                         Ok(refund) => {
844                                 assert_eq!(refund.absolute_expiry(), Some(past_expiry));
845                                 #[cfg(feature = "std")]
846                                 assert!(refund.is_expired());
847                                 assert_eq!(refund.paths(), &paths[..]);
848                                 assert_eq!(refund.issuer(), Some(PrintableString("bar")));
849                                 assert_eq!(refund.chain(), ChainHash::using_genesis_block(Network::Testnet));
850                                 assert_eq!(refund.features(), &InvoiceRequestFeatures::unknown());
851                                 assert_eq!(refund.payer_note(), Some(PrintableString("baz")));
852                         },
853                         Err(e) => panic!("error parsing refund: {:?}", e),
854                 }
855         }
856
857         #[test]
858         fn fails_parsing_refund_with_unexpected_fields() {
859                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], payer_pubkey(), 1000).unwrap()
860                         .build().unwrap();
861                 if let Err(e) = refund.to_string().parse::<Refund>() {
862                         panic!("error parsing refund: {:?}", e);
863                 }
864
865                 let chains = vec![ChainHash::using_genesis_block(Network::Testnet)];
866                 let mut tlv_stream = refund.as_tlv_stream();
867                 tlv_stream.1.chains = Some(&chains);
868
869                 match Refund::try_from(tlv_stream.to_bytes()) {
870                         Ok(_) => panic!("expected error"),
871                         Err(e) => {
872                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::UnexpectedChain));
873                         },
874                 }
875
876                 let mut tlv_stream = refund.as_tlv_stream();
877                 tlv_stream.1.currency = Some(&b"USD");
878                 tlv_stream.1.amount = Some(1000);
879
880                 match Refund::try_from(tlv_stream.to_bytes()) {
881                         Ok(_) => panic!("expected error"),
882                         Err(e) => {
883                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::UnexpectedAmount));
884                         },
885                 }
886
887                 let features = OfferFeatures::unknown();
888                 let mut tlv_stream = refund.as_tlv_stream();
889                 tlv_stream.1.features = Some(&features);
890
891                 match Refund::try_from(tlv_stream.to_bytes()) {
892                         Ok(_) => panic!("expected error"),
893                         Err(e) => {
894                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::UnexpectedFeatures));
895                         },
896                 }
897
898                 let mut tlv_stream = refund.as_tlv_stream();
899                 tlv_stream.1.quantity_max = Some(10);
900
901                 match Refund::try_from(tlv_stream.to_bytes()) {
902                         Ok(_) => panic!("expected error"),
903                         Err(e) => {
904                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::UnexpectedQuantity));
905                         },
906                 }
907
908                 let node_id = payer_pubkey();
909                 let mut tlv_stream = refund.as_tlv_stream();
910                 tlv_stream.1.node_id = Some(&node_id);
911
912                 match Refund::try_from(tlv_stream.to_bytes()) {
913                         Ok(_) => panic!("expected error"),
914                         Err(e) => {
915                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::UnexpectedSigningPubkey));
916                         },
917                 }
918
919                 let mut tlv_stream = refund.as_tlv_stream();
920                 tlv_stream.2.quantity = Some(10);
921
922                 match Refund::try_from(tlv_stream.to_bytes()) {
923                         Ok(_) => panic!("expected error"),
924                         Err(e) => {
925                                 assert_eq!(e, ParseError::InvalidSemantics(SemanticError::UnexpectedQuantity));
926                         },
927                 }
928         }
929
930         #[test]
931         fn fails_parsing_refund_with_extra_tlv_records() {
932                 let secp_ctx = Secp256k1::new();
933                 let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
934                 let refund = RefundBuilder::new("foo".into(), vec![1; 32], keys.public_key(), 1000).unwrap()
935                         .build().unwrap();
936
937                 let mut encoded_refund = Vec::new();
938                 refund.write(&mut encoded_refund).unwrap();
939                 BigSize(1002).write(&mut encoded_refund).unwrap();
940                 BigSize(32).write(&mut encoded_refund).unwrap();
941                 [42u8; 32].write(&mut encoded_refund).unwrap();
942
943                 match Refund::try_from(encoded_refund) {
944                         Ok(_) => panic!("expected error"),
945                         Err(e) => assert_eq!(e, ParseError::Decode(DecodeError::InvalidValue)),
946                 }
947         }
948 }