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Add counterparty_node_id & channel_capacity to ChannelClosed
[rust-lightning] / lightning / src / ln / features.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 //! Feature flag definitions for the Lightning protocol according to [BOLT #9].
11 //!
12 //! Lightning nodes advertise a supported set of operation through feature flags. Features are
13 //! applicable for a specific context as indicated in some [messages]. [`Features`] encapsulates
14 //! behavior for specifying and checking feature flags for a particular context. Each feature is
15 //! defined internally by a trait specifying the corresponding flags (i.e., even and odd bits).
16 //!
17 //! Whether a feature is considered "known" or "unknown" is relative to the implementation, whereas
18 //! the term "supports" is used in reference to a particular set of [`Features`]. That is, a node
19 //! supports a feature if it advertises the feature (as either required or optional) to its peers.
20 //! And the implementation can interpret a feature if the feature is known to it.
21 //!
22 //! The following features are currently required in the LDK:
23 //! - `VariableLengthOnion` - requires/supports variable-length routing onion payloads
24 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md) for more information).
25 //! - `StaticRemoteKey` - requires/supports static key for remote output
26 //!     (see [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more information).
27 //!
28 //! The following features are currently supported in the LDK:
29 //! - `DataLossProtect` - requires/supports that a node which has somehow fallen behind, e.g., has been restored from an old backup,
30 //!     can detect that it has fallen behind
31 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
32 //! - `InitialRoutingSync` - requires/supports that the sending node needs a complete routing information dump
33 //!     (see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#initial-sync) for more information).
34 //! - `UpfrontShutdownScript` - commits to a shutdown scriptpubkey when opening a channel
35 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-open_channel-message) for more information).
36 //! - `GossipQueries` - requires/supports more sophisticated gossip control
37 //!     (see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md) for more information).
38 //! - `PaymentSecret` - requires/supports that a node supports payment_secret field
39 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md) for more information).
40 //! - `BasicMPP` - requires/supports that a node can receive basic multi-part payments
41 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md#basic-multi-part-payments) for more information).
42 //! - `Wumbo` - requires/supports that a node create large channels. Called `option_support_large_channel` in the spec.
43 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-open_channel-message) for more information).
44 //! - `ShutdownAnySegwit` - requires/supports that future segwit versions are allowed in `shutdown`
45 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
46 //! - `OnionMessages` - requires/supports forwarding onion messages
47 //!     (see [BOLT-7](https://github.com/lightning/bolts/pull/759/files) for more information).
48 //     TODO: update link
49 //! - `ChannelType` - node supports the channel_type field in open/accept
50 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
51 //! - `SCIDPrivacy` - supply channel aliases for routing
52 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
53 //! - `PaymentMetadata` - include additional data in invoices which is passed to recipients in the
54 //!      onion.
55 //!      (see [BOLT-11](https://github.com/lightning/bolts/blob/master/11-payment-encoding.md) for
56 //!      more).
57 //! - `ZeroConf` - supports accepting HTLCs and using channels prior to funding confirmation
58 //!      (see
59 //!      [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-channel_ready-message)
60 //!      for more info).
61 //! - `Keysend` - send funds to a node without an invoice
62 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
63 //! - `AnchorsZeroFeeHtlcTx` - requires/supports that commitment transactions include anchor outputs
64 //!     and HTLC transactions are pre-signed with zero fee (see
65 //!     [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more
66 //!     information).
67 //!
68 //! LDK knows about the following features, but does not support them:
69 //! - `AnchorsNonzeroFeeHtlcTx` - the initial version of anchor outputs, which was later found to be
70 //!     vulnerable (see this
71 //!     [mailing list post](https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-September/002796.html)
72 //!     for more information).
73 //!
74 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
75 //! [messages]: crate::ln::msgs
76
77 use crate::{io, io_extras};
78 use crate::prelude::*;
79 use core::{cmp, fmt};
80 use core::borrow::Borrow;
81 use core::hash::{Hash, Hasher};
82 use core::marker::PhantomData;
83
84 use bitcoin::bech32;
85 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
86 use crate::ln::msgs::DecodeError;
87 use crate::util::ser::{Readable, WithoutLength, Writeable, Writer};
88
89 mod sealed {
90         use crate::prelude::*;
91         use crate::ln::features::Features;
92
93         /// The context in which [`Features`] are applicable. Defines which features are known to the
94         /// implementation, though specification of them as required or optional is up to the code
95         /// constructing a features object.
96         pub trait Context {
97                 /// Bitmask for selecting features that are known to the implementation.
98                 const KNOWN_FEATURE_MASK: &'static [u8];
99         }
100
101         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
102         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
103         /// feature identifiers.
104         macro_rules! define_context {
105                 ($context: ident, [$( $( $known_feature: ident )|*, )*]) => {
106                         #[derive(Eq, PartialEq)]
107                         pub struct $context {}
108
109                         impl Context for $context {
110                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
111                                         $(
112                                                 0b00_00_00_00 $(|
113                                                         <Self as $known_feature>::REQUIRED_MASK |
114                                                         <Self as $known_feature>::OPTIONAL_MASK)*,
115                                         )*
116                                 ];
117                         }
118
119                         impl alloc::fmt::Display for Features<$context> {
120                                 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
121                                         $(
122                                                 $(
123                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($known_feature),
124                                                                 if <$context as $known_feature>::requires_feature(&self.flags) { "required" }
125                                                                 else if <$context as $known_feature>::supports_feature(&self.flags) { "supported" }
126                                                                 else { "not supported" }))?;
127                                                 )*
128                                                 {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
129                                         )*
130                                         fmt.write_fmt(format_args!("unknown flags: {}",
131                                                 if self.requires_unknown_bits() { "required" }
132                                                 else if self.supports_unknown_bits() { "supported" } else { "none" }))
133                                 }
134                         }
135                 };
136         }
137
138         define_context!(InitContext, [
139                 // Byte 0
140                 DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
141                 // Byte 1
142                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
143                 // Byte 2
144                 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
145                 // Byte 3
146                 ShutdownAnySegwit,
147                 // Byte 4
148                 OnionMessages,
149                 // Byte 5
150                 ChannelType | SCIDPrivacy,
151                 // Byte 6
152                 ZeroConf,
153         ]);
154         define_context!(NodeContext, [
155                 // Byte 0
156                 DataLossProtect | UpfrontShutdownScript | GossipQueries,
157                 // Byte 1
158                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
159                 // Byte 2
160                 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
161                 // Byte 3
162                 ShutdownAnySegwit,
163                 // Byte 4
164                 OnionMessages,
165                 // Byte 5
166                 ChannelType | SCIDPrivacy,
167                 // Byte 6
168                 ZeroConf | Keysend,
169         ]);
170         define_context!(ChannelContext, []);
171         define_context!(Bolt11InvoiceContext, [
172                 // Byte 0
173                 ,
174                 // Byte 1
175                 VariableLengthOnion | PaymentSecret,
176                 // Byte 2
177                 BasicMPP,
178                 // Byte 3
179                 ,
180                 // Byte 4
181                 ,
182                 // Byte 5
183                 ,
184                 // Byte 6
185                 PaymentMetadata,
186         ]);
187         define_context!(OfferContext, []);
188         define_context!(InvoiceRequestContext, []);
189         define_context!(Bolt12InvoiceContext, [
190                 // Byte 0
191                 ,
192                 // Byte 1
193                 ,
194                 // Byte 2
195                 BasicMPP,
196         ]);
197         define_context!(BlindedHopContext, []);
198         // This isn't a "real" feature context, and is only used in the channel_type field in an
199         // `OpenChannel` message.
200         define_context!(ChannelTypeContext, [
201                 // Byte 0
202                 ,
203                 // Byte 1
204                 StaticRemoteKey,
205                 // Byte 2
206                 AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
207                 // Byte 3
208                 ,
209                 // Byte 4
210                 ,
211                 // Byte 5
212                 SCIDPrivacy,
213                 // Byte 6
214                 ZeroConf,
215         ]);
216
217         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
218         /// useful for manipulating feature flags.
219         macro_rules! define_feature {
220                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
221                  $required_setter: ident, $supported_getter: ident) => {
222                         #[doc = $doc]
223                         ///
224                         /// See [BOLT #9] for details.
225                         ///
226                         /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
227                         pub trait $feature: Context {
228                                 /// The bit used to signify that the feature is required.
229                                 const EVEN_BIT: usize = $odd_bit - 1;
230
231                                 /// The bit used to signify that the feature is optional.
232                                 const ODD_BIT: usize = $odd_bit;
233
234                                 /// Assertion that [`EVEN_BIT`] is actually even.
235                                 ///
236                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
237                                 const ASSERT_EVEN_BIT_PARITY: usize;
238
239                                 /// Assertion that [`ODD_BIT`] is actually odd.
240                                 ///
241                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
242                                 const ASSERT_ODD_BIT_PARITY: usize;
243
244                                 /// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
245                                 ///
246                                 /// [`KNOWN_FEATURE_MASK`]: Context::KNOWN_FEATURE_MASK
247                                 #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
248                                 const ASSERT_BITS_IN_MASK: u8;
249
250                                 /// The byte where the feature is set.
251                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
252
253                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
254                                 ///
255                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
256                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
257
258                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
259                                 ///
260                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
261                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
262
263                                 /// Returns whether the feature is required by the given flags.
264                                 #[inline]
265                                 fn requires_feature(flags: &Vec<u8>) -> bool {
266                                         flags.len() > Self::BYTE_OFFSET &&
267                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
268                                 }
269
270                                 /// Returns whether the feature is supported by the given flags.
271                                 #[inline]
272                                 fn supports_feature(flags: &Vec<u8>) -> bool {
273                                         flags.len() > Self::BYTE_OFFSET &&
274                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
275                                 }
276
277                                 /// Sets the feature's required (even) bit in the given flags.
278                                 #[inline]
279                                 fn set_required_bit(flags: &mut Vec<u8>) {
280                                         if flags.len() <= Self::BYTE_OFFSET {
281                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
282                                         }
283
284                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
285                                         flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
286                                 }
287
288                                 /// Sets the feature's optional (odd) bit in the given flags.
289                                 #[inline]
290                                 fn set_optional_bit(flags: &mut Vec<u8>) {
291                                         if flags.len() <= Self::BYTE_OFFSET {
292                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
293                                         }
294
295                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
296                                 }
297
298                                 /// Clears the feature's required (even) and optional (odd) bits from the given
299                                 /// flags.
300                                 #[inline]
301                                 fn clear_bits(flags: &mut Vec<u8>) {
302                                         if flags.len() > Self::BYTE_OFFSET {
303                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
304                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
305                                         }
306
307                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
308                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
309                                         flags.resize(size, 0u8);
310                                 }
311                         }
312
313                         impl <T: $feature> Features<T> {
314                                 /// Set this feature as optional.
315                                 pub fn $optional_setter(&mut self) {
316                                         <T as $feature>::set_optional_bit(&mut self.flags);
317                                 }
318
319                                 /// Set this feature as required.
320                                 pub fn $required_setter(&mut self) {
321                                         <T as $feature>::set_required_bit(&mut self.flags);
322                                 }
323
324                                 /// Checks if this feature is supported.
325                                 pub fn $supported_getter(&self) -> bool {
326                                         <T as $feature>::supports_feature(&self.flags)
327                                 }
328                         }
329
330                         $(
331                                 impl $feature for $context {
332                                         // EVEN_BIT % 2 == 0
333                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
334
335                                         // ODD_BIT % 2 == 1
336                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
337
338                                         // (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
339                                         #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
340                                         const ASSERT_BITS_IN_MASK: u8 =
341                                                 ((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
342                                                  >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
343                                 }
344                         )*
345                 };
346                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
347                  $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
348                         define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
349                         impl <T: $feature> Features<T> {
350                                 /// Checks if this feature is required.
351                                 pub fn $required_getter(&self) -> bool {
352                                         <T as $feature>::requires_feature(&self.flags)
353                                 }
354                         }
355                 }
356         }
357
358         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
359                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
360                 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
361         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
362         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
363                 set_initial_routing_sync_optional, set_initial_routing_sync_required,
364                 initial_routing_sync);
365         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
366                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
367                 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
368                 requires_upfront_shutdown_script);
369         define_feature!(7, GossipQueries, [InitContext, NodeContext],
370                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
371                 supports_gossip_queries, requires_gossip_queries);
372         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, Bolt11InvoiceContext],
373                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
374                 set_variable_length_onion_required, supports_variable_length_onion,
375                 requires_variable_length_onion);
376         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
377                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
378                 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
379         define_feature!(15, PaymentSecret, [InitContext, NodeContext, Bolt11InvoiceContext],
380                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
381                 supports_payment_secret, requires_payment_secret);
382         define_feature!(17, BasicMPP, [InitContext, NodeContext, Bolt11InvoiceContext, Bolt12InvoiceContext],
383                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
384                 supports_basic_mpp, requires_basic_mpp);
385         define_feature!(19, Wumbo, [InitContext, NodeContext],
386                 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
387                 supports_wumbo, requires_wumbo);
388         define_feature!(21, AnchorsNonzeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
389                 "Feature flags for `option_anchors_nonzero_fee_htlc_tx`.", set_anchors_nonzero_fee_htlc_tx_optional,
390                 set_anchors_nonzero_fee_htlc_tx_required, supports_anchors_nonzero_fee_htlc_tx, requires_anchors_nonzero_fee_htlc_tx);
391         define_feature!(23, AnchorsZeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
392                 "Feature flags for `option_anchors_zero_fee_htlc_tx`.", set_anchors_zero_fee_htlc_tx_optional,
393                 set_anchors_zero_fee_htlc_tx_required, supports_anchors_zero_fee_htlc_tx, requires_anchors_zero_fee_htlc_tx);
394         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
395                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
396                 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
397         define_feature!(39, OnionMessages, [InitContext, NodeContext],
398                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
399                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
400         define_feature!(45, ChannelType, [InitContext, NodeContext],
401                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
402                 set_channel_type_required, supports_channel_type, requires_channel_type);
403         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
404                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
405                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
406         define_feature!(49, PaymentMetadata, [Bolt11InvoiceContext],
407                 "Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
408                 set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
409         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
410                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
411                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
412         define_feature!(55, Keysend, [NodeContext],
413                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
414                 supports_keysend, requires_keysend);
415         // Note: update the module-level docs when a new feature bit is added!
416
417         #[cfg(test)]
418         define_feature!(123456789, UnknownFeature,
419                 [NodeContext, ChannelContext, Bolt11InvoiceContext, OfferContext, InvoiceRequestContext, Bolt12InvoiceContext, BlindedHopContext],
420                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
421                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
422 }
423
424 /// Tracks the set of features which a node implements, templated by the context in which it
425 /// appears.
426 ///
427 /// This is not exported to bindings users as we map the concrete feature types below directly instead
428 #[derive(Eq)]
429 pub struct Features<T: sealed::Context> {
430         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
431         flags: Vec<u8>,
432         mark: PhantomData<T>,
433 }
434
435 impl<T: sealed::Context, Rhs: Borrow<Self>> core::ops::BitOrAssign<Rhs> for Features<T> {
436         fn bitor_assign(&mut self, rhs: Rhs) {
437                 let total_feature_len = cmp::max(self.flags.len(), rhs.borrow().flags.len());
438                 self.flags.resize(total_feature_len, 0u8);
439                 for (byte, rhs_byte) in self.flags.iter_mut().zip(rhs.borrow().flags.iter()) {
440                         *byte |= *rhs_byte;
441                 }
442         }
443 }
444
445 impl<T: sealed::Context> core::ops::BitOr for Features<T> {
446         type Output = Self;
447
448         fn bitor(mut self, o: Self) -> Self {
449                 self |= o;
450                 self
451         }
452 }
453
454 impl<T: sealed::Context> Clone for Features<T> {
455         fn clone(&self) -> Self {
456                 Self {
457                         flags: self.flags.clone(),
458                         mark: PhantomData,
459                 }
460         }
461 }
462 impl<T: sealed::Context> Hash for Features<T> {
463         fn hash<H: Hasher>(&self, hasher: &mut H) {
464                 self.flags.hash(hasher);
465         }
466 }
467 impl<T: sealed::Context> PartialEq for Features<T> {
468         fn eq(&self, o: &Self) -> bool {
469                 self.flags.eq(&o.flags)
470         }
471 }
472 impl<T: sealed::Context> PartialOrd for Features<T> {
473         fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
474                 self.flags.partial_cmp(&other.flags)
475         }
476 }
477 impl<T: sealed::Context + Eq> Ord for Features<T> {
478         fn cmp(&self, other: &Self) -> cmp::Ordering {
479                 self.flags.cmp(&other.flags)
480         }
481 }
482 impl<T: sealed::Context> fmt::Debug for Features<T> {
483         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
484                 self.flags.fmt(fmt)
485         }
486 }
487
488 /// Features used within an `init` message.
489 pub type InitFeatures = Features<sealed::InitContext>;
490 /// Features used within a `node_announcement` message.
491 pub type NodeFeatures = Features<sealed::NodeContext>;
492 /// Features used within a `channel_announcement` message.
493 pub type ChannelFeatures = Features<sealed::ChannelContext>;
494 /// Features used within an invoice.
495 pub type Bolt11InvoiceFeatures = Features<sealed::Bolt11InvoiceContext>;
496 /// Features used within an `offer`.
497 pub type OfferFeatures = Features<sealed::OfferContext>;
498 /// Features used within an `invoice_request`.
499 pub type InvoiceRequestFeatures = Features<sealed::InvoiceRequestContext>;
500 /// Features used within an `invoice`.
501 pub type Bolt12InvoiceFeatures = Features<sealed::Bolt12InvoiceContext>;
502 /// Features used within BOLT 4 encrypted_data_tlv and BOLT 12 blinded_payinfo
503 pub type BlindedHopFeatures = Features<sealed::BlindedHopContext>;
504
505 /// Features used within the channel_type field in an OpenChannel message.
506 ///
507 /// A channel is always of some known "type", describing the transaction formats used and the exact
508 /// semantics of our interaction with our peer.
509 ///
510 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
511 /// the counterparty, only required features are allowed here.
512 ///
513 /// This is serialized differently from other feature types - it is not prefixed by a length, and
514 /// thus must only appear inside a TLV where its length is known in advance.
515 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
516
517 impl InitFeatures {
518         /// Writes all features present up to, and including, 13.
519         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
520                 let len = cmp::min(2, self.flags.len());
521                 (len as u16).write(w)?;
522                 for i in (0..len).rev() {
523                         if i == 0 {
524                                 self.flags[i].write(w)?;
525                         } else {
526                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
527                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
528                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
529                         }
530                 }
531                 Ok(())
532         }
533
534         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
535         /// are included in the result.
536         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
537                 self.to_context_internal()
538         }
539 }
540
541 impl Bolt11InvoiceFeatures {
542         /// Converts `Bolt11InvoiceFeatures` to `Features<C>`. Only known `Bolt11InvoiceFeatures` relevant to
543         /// context `C` are included in the result.
544         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
545                 self.to_context_internal()
546         }
547
548         /// Getting a route for a keysend payment to a private node requires providing the payee's
549         /// features (since they were not announced in a node announcement). However, keysend payments
550         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
551         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
552         /// `Bolt11InvoiceFeatures` for [`find_route`].
553         ///
554         /// MPP keysend is not widely supported yet, so we parameterize support to allow the user to
555         /// choose whether their router should find multi-part routes.
556         ///
557         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
558         /// [`find_route`]: crate::routing::router::find_route
559         pub(crate) fn for_keysend(allow_mpp: bool) -> Bolt11InvoiceFeatures {
560                 let mut res = Bolt11InvoiceFeatures::empty();
561                 res.set_variable_length_onion_optional();
562                 if allow_mpp {
563                         res.set_basic_mpp_optional();
564                 }
565                 res
566         }
567 }
568
569 impl Bolt12InvoiceFeatures {
570         /// Converts [`Bolt12InvoiceFeatures`] to [`Features<C>`]. Only known [`Bolt12InvoiceFeatures`]
571         /// relevant to context `C` are included in the result.
572         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
573                 self.to_context_internal()
574         }
575 }
576
577 impl ChannelTypeFeatures {
578         // Maps the relevant `InitFeatures` to `ChannelTypeFeatures`. Any unknown features to
579         // `ChannelTypeFeatures` are not included in the result.
580         pub(crate) fn from_init(init: &InitFeatures) -> Self {
581                 let mut ret = init.to_context_internal();
582                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
583                 // optional bits and then AND out the optional ones.
584                 for byte in ret.flags.iter_mut() {
585                         *byte |= (*byte & 0b10_10_10_10) >> 1;
586                         *byte &= 0b01_01_01_01;
587                 }
588                 ret
589         }
590
591         /// Constructs a ChannelTypeFeatures with only static_remotekey set
592         pub(crate) fn only_static_remote_key() -> Self {
593                 let mut ret = Self::empty();
594                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
595                 ret
596         }
597
598         /// Constructs a ChannelTypeFeatures with anchors support
599         pub(crate) fn anchors_zero_htlc_fee_and_dependencies() -> Self {
600                 let mut ret = Self::empty();
601                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
602                 <sealed::ChannelTypeContext as sealed::AnchorsZeroFeeHtlcTx>::set_required_bit(&mut ret.flags);
603                 ret
604         }
605 }
606
607 impl ToBase32 for Bolt11InvoiceFeatures {
608         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
609                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
610                 // minus one before dividing
611                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
612                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
613                 for (byte_idx, byte) in self.flags.iter().enumerate() {
614                         let bit_pos_from_left_0_indexed = byte_idx * 8;
615                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
616                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
617                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
618                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
619                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
620                         if new_u5_idx > 0 {
621                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
622                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
623                         }
624                         if new_u5_idx > 1 {
625                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
626                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
627                         }
628                 }
629                 // Trim the highest feature bits.
630                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
631                         res_u5s.remove(0);
632                 }
633                 writer.write(&res_u5s)
634         }
635 }
636
637 impl Base32Len for Bolt11InvoiceFeatures {
638         fn base32_len(&self) -> usize {
639                 self.to_base32().len()
640         }
641 }
642
643 impl FromBase32 for Bolt11InvoiceFeatures {
644         type Err = bech32::Error;
645
646         fn from_base32(field_data: &[u5]) -> Result<Bolt11InvoiceFeatures, bech32::Error> {
647                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
648                 // minus one before dividing
649                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
650                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
651                 for (u5_idx, chunk) in field_data.iter().enumerate() {
652                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
653                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
654                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
655                         let chunk_u16 = chunk.to_u8() as u16;
656                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
657                         if new_byte_idx != length_bytes - 1 {
658                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
659                         }
660                 }
661                 // Trim the highest feature bits.
662                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
663                         res_bytes.pop();
664                 }
665                 Ok(Bolt11InvoiceFeatures::from_le_bytes(res_bytes))
666         }
667 }
668
669 impl<T: sealed::Context> Features<T> {
670         /// Create a blank Features with no features set
671         pub fn empty() -> Self {
672                 Features {
673                         flags: Vec::new(),
674                         mark: PhantomData,
675                 }
676         }
677
678         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
679         /// included in the result.
680         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
681                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
682                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
683                 let mut flags = Vec::new();
684                 for (i, byte) in self.flags.iter().enumerate() {
685                         if i < from_byte_count && i < to_byte_count {
686                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
687                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
688                                 flags.push(byte & from_known_features & to_known_features);
689                         }
690                 }
691                 Features::<C> { flags, mark: PhantomData, }
692         }
693
694         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
695         /// most on-the-wire encodings.
696         ///
697         /// This is not exported to bindings users as we don't support export across multiple T
698         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
699                 Features {
700                         flags,
701                         mark: PhantomData,
702                 }
703         }
704
705         #[cfg(test)]
706         /// Gets the underlying flags set, in LE.
707         pub fn le_flags(&self) -> &Vec<u8> {
708                 &self.flags
709         }
710
711         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
712                 for f in self.flags.iter().rev() { // Swap back to big-endian
713                         f.write(w)?;
714                 }
715                 Ok(())
716         }
717
718         fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
719                 flags.reverse(); // Swap to little-endian
720                 Self {
721                         flags,
722                         mark: PhantomData,
723                 }
724         }
725
726         pub(crate) fn supports_any_optional_bits(&self) -> bool {
727                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
728         }
729
730         /// Returns true if this `Features` object contains required features unknown by `other`.
731         pub fn requires_unknown_bits_from(&self, other: &Self) -> bool {
732                 // Bitwise AND-ing with all even bits set except for known features will select required
733                 // unknown features.
734                 self.flags.iter().enumerate().any(|(i, &byte)| {
735                         const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
736                         const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
737                         let unknown_features = if i < other.flags.len() {
738                                 // Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
739                                 !(other.flags[i]
740                                         | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
741                                         | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
742                         } else {
743                                 0b11_11_11_11
744                         };
745                         (byte & (REQUIRED_FEATURES & unknown_features)) != 0
746                 })
747         }
748
749         /// Returns true if this `Features` object contains unknown feature flags which are set as
750         /// "required".
751         pub fn requires_unknown_bits(&self) -> bool {
752                 // Bitwise AND-ing with all even bits set except for known features will select required
753                 // unknown features.
754                 let byte_count = T::KNOWN_FEATURE_MASK.len();
755                 self.flags.iter().enumerate().any(|(i, &byte)| {
756                         let required_features = 0b01_01_01_01;
757                         let unknown_features = if i < byte_count {
758                                 !T::KNOWN_FEATURE_MASK[i]
759                         } else {
760                                 0b11_11_11_11
761                         };
762                         (byte & (required_features & unknown_features)) != 0
763                 })
764         }
765
766         pub(crate) fn supports_unknown_bits(&self) -> bool {
767                 // Bitwise AND-ing with all even and odd bits set except for known features will select
768                 // both required and optional unknown features.
769                 let byte_count = T::KNOWN_FEATURE_MASK.len();
770                 self.flags.iter().enumerate().any(|(i, &byte)| {
771                         let unknown_features = if i < byte_count {
772                                 !T::KNOWN_FEATURE_MASK[i]
773                         } else {
774                                 0b11_11_11_11
775                         };
776                         (byte & unknown_features) != 0
777                 })
778         }
779
780         // Returns true if the features within `self` are a subset of the features within `other`.
781         pub(crate) fn is_subset(&self, other: &Self) -> bool {
782                 for (idx, byte) in self.flags.iter().enumerate() {
783                         if let Some(other_byte) = other.flags.get(idx) {
784                                 if byte & other_byte != *byte {
785                                         // `self` has bits set that `other` doesn't.
786                                         return false;
787                                 }
788                         } else {
789                                 if *byte > 0 {
790                                         // `self` has a non-zero byte that `other` doesn't.
791                                         return false;
792                                 }
793                         }
794                 }
795                 true
796         }
797
798         /// Sets a required custom feature bit. Errors if `bit` is outside the custom range as defined
799         /// by [bLIP 2] or if it is a known `T` feature.
800         ///
801         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
802         /// be set instead (i.e., `bit - 1`).
803         ///
804         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
805         pub fn set_required_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
806                 self.set_custom_bit(bit - (bit % 2))
807         }
808
809         /// Sets an optional custom feature bit. Errors if `bit` is outside the custom range as defined
810         /// by [bLIP 2] or if it is a known `T` feature.
811         ///
812         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
813         /// set instead (i.e., `bit + 1`).
814         ///
815         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
816         pub fn set_optional_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
817                 self.set_custom_bit(bit + (1 - (bit % 2)))
818         }
819
820         fn set_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
821                 if bit < 256 {
822                         return Err(());
823                 }
824
825                 let byte_offset = bit / 8;
826                 let mask = 1 << (bit - 8 * byte_offset);
827                 if byte_offset < T::KNOWN_FEATURE_MASK.len() {
828                         if (T::KNOWN_FEATURE_MASK[byte_offset] & mask) != 0 {
829                                 return Err(());
830                         }
831                 }
832
833                 if self.flags.len() <= byte_offset {
834                         self.flags.resize(byte_offset + 1, 0u8);
835                 }
836
837                 self.flags[byte_offset] |= mask;
838
839                 Ok(())
840         }
841 }
842
843 impl<T: sealed::UpfrontShutdownScript> Features<T> {
844         #[cfg(test)]
845         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
846                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
847                 self
848         }
849 }
850
851 impl<T: sealed::ShutdownAnySegwit> Features<T> {
852         #[cfg(test)]
853         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
854                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
855                 self
856         }
857 }
858
859 impl<T: sealed::Wumbo> Features<T> {
860         #[cfg(test)]
861         pub(crate) fn clear_wumbo(mut self) -> Self {
862                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
863                 self
864         }
865 }
866
867 impl<T: sealed::SCIDPrivacy> Features<T> {
868         pub(crate) fn clear_scid_privacy(&mut self) {
869                 <T as sealed::SCIDPrivacy>::clear_bits(&mut self.flags);
870         }
871 }
872
873 impl<T: sealed::AnchorsZeroFeeHtlcTx> Features<T> {
874         pub(crate) fn clear_anchors_zero_fee_htlc_tx(&mut self) {
875                 <T as sealed::AnchorsZeroFeeHtlcTx>::clear_bits(&mut self.flags);
876         }
877 }
878
879 #[cfg(test)]
880 impl<T: sealed::UnknownFeature> Features<T> {
881         pub(crate) fn unknown() -> Self {
882                 let mut features = Self::empty();
883                 features.set_unknown_feature_required();
884                 features
885         }
886 }
887
888 macro_rules! impl_feature_len_prefixed_write {
889         ($features: ident) => {
890                 impl Writeable for $features {
891                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
892                                 (self.flags.len() as u16).write(w)?;
893                                 self.write_be(w)
894                         }
895                 }
896                 impl Readable for $features {
897                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
898                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
899                         }
900                 }
901         }
902 }
903 impl_feature_len_prefixed_write!(InitFeatures);
904 impl_feature_len_prefixed_write!(ChannelFeatures);
905 impl_feature_len_prefixed_write!(NodeFeatures);
906 impl_feature_len_prefixed_write!(Bolt11InvoiceFeatures);
907 impl_feature_len_prefixed_write!(Bolt12InvoiceFeatures);
908 impl_feature_len_prefixed_write!(BlindedHopFeatures);
909
910 // Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
911 macro_rules! impl_feature_tlv_write {
912         ($features: ident) => {
913                 impl Writeable for $features {
914                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
915                                 WithoutLength(self).write(w)
916                         }
917                 }
918                 impl Readable for $features {
919                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
920                                 Ok(WithoutLength::<Self>::read(r)?.0)
921                         }
922                 }
923         }
924 }
925
926 impl_feature_tlv_write!(ChannelTypeFeatures);
927
928 // Some features may appear both in a TLV record and as part of a TLV subtype sequence. The latter
929 // requires a length but the former does not.
930
931 impl<T: sealed::Context> Writeable for WithoutLength<&Features<T>> {
932         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
933                 self.0.write_be(w)
934         }
935 }
936
937 impl<T: sealed::Context> Readable for WithoutLength<Features<T>> {
938         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
939                 let v = io_extras::read_to_end(r)?;
940                 Ok(WithoutLength(Features::<T>::from_be_bytes(v)))
941         }
942 }
943
944 #[cfg(test)]
945 mod tests {
946         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, Bolt11InvoiceFeatures, NodeFeatures, OfferFeatures, sealed};
947         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
948         use crate::util::ser::{Readable, WithoutLength, Writeable};
949
950         #[test]
951         fn sanity_test_unknown_bits() {
952                 let features = ChannelFeatures::empty();
953                 assert!(!features.requires_unknown_bits());
954                 assert!(!features.supports_unknown_bits());
955
956                 let mut features = ChannelFeatures::empty();
957                 features.set_unknown_feature_required();
958                 assert!(features.requires_unknown_bits());
959                 assert!(features.supports_unknown_bits());
960
961                 let mut features = ChannelFeatures::empty();
962                 features.set_unknown_feature_optional();
963                 assert!(!features.requires_unknown_bits());
964                 assert!(features.supports_unknown_bits());
965         }
966
967         #[test]
968         fn requires_unknown_bits_from() {
969                 let mut features1 = InitFeatures::empty();
970                 let mut features2 = InitFeatures::empty();
971                 assert!(!features1.requires_unknown_bits_from(&features2));
972                 assert!(!features2.requires_unknown_bits_from(&features1));
973
974                 features1.set_data_loss_protect_required();
975                 assert!(features1.requires_unknown_bits_from(&features2));
976                 assert!(!features2.requires_unknown_bits_from(&features1));
977
978                 features2.set_data_loss_protect_optional();
979                 assert!(!features1.requires_unknown_bits_from(&features2));
980                 assert!(!features2.requires_unknown_bits_from(&features1));
981
982                 features2.set_gossip_queries_required();
983                 assert!(!features1.requires_unknown_bits_from(&features2));
984                 assert!(features2.requires_unknown_bits_from(&features1));
985
986                 features1.set_gossip_queries_optional();
987                 assert!(!features1.requires_unknown_bits_from(&features2));
988                 assert!(!features2.requires_unknown_bits_from(&features1));
989
990                 features1.set_variable_length_onion_required();
991                 assert!(features1.requires_unknown_bits_from(&features2));
992                 assert!(!features2.requires_unknown_bits_from(&features1));
993
994                 features2.set_variable_length_onion_optional();
995                 assert!(!features1.requires_unknown_bits_from(&features2));
996                 assert!(!features2.requires_unknown_bits_from(&features1));
997
998                 features1.set_basic_mpp_required();
999                 features2.set_wumbo_required();
1000                 assert!(features1.requires_unknown_bits_from(&features2));
1001                 assert!(features2.requires_unknown_bits_from(&features1));
1002         }
1003
1004         #[test]
1005         fn convert_to_context_with_relevant_flags() {
1006                 let mut init_features = InitFeatures::empty();
1007                 // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
1008                 // converted as it's only relevant in an init context).
1009                 init_features.set_initial_routing_sync_required();
1010                 init_features.set_data_loss_protect_required();
1011                 init_features.set_variable_length_onion_required();
1012                 init_features.set_static_remote_key_required();
1013                 init_features.set_payment_secret_required();
1014                 init_features.set_basic_mpp_optional();
1015                 init_features.set_wumbo_optional();
1016                 init_features.set_anchors_zero_fee_htlc_tx_optional();
1017                 init_features.set_shutdown_any_segwit_optional();
1018                 init_features.set_onion_messages_optional();
1019                 init_features.set_channel_type_optional();
1020                 init_features.set_scid_privacy_optional();
1021                 init_features.set_zero_conf_optional();
1022
1023                 assert!(init_features.initial_routing_sync());
1024                 assert!(!init_features.supports_upfront_shutdown_script());
1025                 assert!(!init_features.supports_gossip_queries());
1026
1027                 let node_features: NodeFeatures = init_features.to_context();
1028                 {
1029                         // Check that the flags are as expected:
1030                         // - option_data_loss_protect (req)
1031                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
1032                         // - basic_mpp | wumbo | anchors_zero_fee_htlc_tx
1033                         // - opt_shutdown_anysegwit
1034                         // - onion_messages
1035                         // - option_channel_type | option_scid_alias
1036                         // - option_zeroconf
1037                         assert_eq!(node_features.flags.len(), 7);
1038                         assert_eq!(node_features.flags[0], 0b00000001);
1039                         assert_eq!(node_features.flags[1], 0b01010001);
1040                         assert_eq!(node_features.flags[2], 0b10001010);
1041                         assert_eq!(node_features.flags[3], 0b00001000);
1042                         assert_eq!(node_features.flags[4], 0b10000000);
1043                         assert_eq!(node_features.flags[5], 0b10100000);
1044                         assert_eq!(node_features.flags[6], 0b00001000);
1045                 }
1046
1047                 // Check that cleared flags are kept blank when converting back:
1048                 // - initial_routing_sync was not applicable to NodeContext
1049                 // - upfront_shutdown_script was cleared before converting
1050                 // - gossip_queries was cleared before converting
1051                 let features: InitFeatures = node_features.to_context_internal();
1052                 assert!(!features.initial_routing_sync());
1053                 assert!(!features.supports_upfront_shutdown_script());
1054                 assert!(!init_features.supports_gossip_queries());
1055         }
1056
1057         #[test]
1058         fn convert_to_context_with_unknown_flags() {
1059                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1060                 assert!(<sealed::ChannelContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
1061                         <sealed::Bolt11InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
1062                 let mut channel_features = ChannelFeatures::empty();
1063                 channel_features.set_unknown_feature_optional();
1064                 assert!(channel_features.supports_unknown_bits());
1065                 let invoice_features: Bolt11InvoiceFeatures = channel_features.to_context_internal();
1066                 assert!(!invoice_features.supports_unknown_bits());
1067         }
1068
1069         #[test]
1070         fn set_feature_bits() {
1071                 let mut features = Bolt11InvoiceFeatures::empty();
1072                 features.set_basic_mpp_optional();
1073                 features.set_payment_secret_required();
1074                 assert!(features.supports_basic_mpp());
1075                 assert!(!features.requires_basic_mpp());
1076                 assert!(features.requires_payment_secret());
1077                 assert!(features.supports_payment_secret());
1078         }
1079
1080         #[test]
1081         fn set_custom_bits() {
1082                 let mut features = Bolt11InvoiceFeatures::empty();
1083                 features.set_variable_length_onion_optional();
1084                 assert_eq!(features.flags[1], 0b00000010);
1085
1086                 assert!(features.set_optional_custom_bit(255).is_err());
1087                 assert!(features.set_required_custom_bit(256).is_ok());
1088                 assert!(features.set_required_custom_bit(258).is_ok());
1089                 assert_eq!(features.flags[31], 0b00000000);
1090                 assert_eq!(features.flags[32], 0b00000101);
1091
1092                 let known_bit = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::EVEN_BIT;
1093                 let byte_offset = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::BYTE_OFFSET;
1094                 assert_eq!(byte_offset, 1);
1095                 assert_eq!(features.flags[byte_offset], 0b00000010);
1096                 assert!(features.set_required_custom_bit(known_bit).is_err());
1097                 assert_eq!(features.flags[byte_offset], 0b00000010);
1098
1099                 let mut features = Bolt11InvoiceFeatures::empty();
1100                 assert!(features.set_optional_custom_bit(256).is_ok());
1101                 assert!(features.set_optional_custom_bit(259).is_ok());
1102                 assert_eq!(features.flags[32], 0b00001010);
1103
1104                 let mut features = Bolt11InvoiceFeatures::empty();
1105                 assert!(features.set_required_custom_bit(257).is_ok());
1106                 assert!(features.set_required_custom_bit(258).is_ok());
1107                 assert_eq!(features.flags[32], 0b00000101);
1108         }
1109
1110         #[test]
1111         fn encodes_features_without_length() {
1112                 let features = OfferFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1113                 assert_eq!(features.flags.len(), 8);
1114
1115                 let mut serialized_features = Vec::new();
1116                 WithoutLength(&features).write(&mut serialized_features).unwrap();
1117                 assert_eq!(serialized_features.len(), 8);
1118
1119                 let deserialized_features =
1120                         WithoutLength::<OfferFeatures>::read(&mut &serialized_features[..]).unwrap().0;
1121                 assert_eq!(features, deserialized_features);
1122         }
1123
1124         #[test]
1125         fn invoice_features_encoding() {
1126                 let features_as_u5s = vec![
1127                         u5::try_from_u8(6).unwrap(),
1128                         u5::try_from_u8(10).unwrap(),
1129                         u5::try_from_u8(25).unwrap(),
1130                         u5::try_from_u8(1).unwrap(),
1131                         u5::try_from_u8(10).unwrap(),
1132                         u5::try_from_u8(0).unwrap(),
1133                         u5::try_from_u8(20).unwrap(),
1134                         u5::try_from_u8(2).unwrap(),
1135                         u5::try_from_u8(0).unwrap(),
1136                         u5::try_from_u8(6).unwrap(),
1137                         u5::try_from_u8(0).unwrap(),
1138                         u5::try_from_u8(16).unwrap(),
1139                         u5::try_from_u8(1).unwrap(),
1140                 ];
1141                 let features = Bolt11InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1142
1143                 // Test length calculation.
1144                 assert_eq!(features.base32_len(), 13);
1145
1146                 // Test serialization.
1147                 let features_serialized = features.to_base32();
1148                 assert_eq!(features_as_u5s, features_serialized);
1149
1150                 // Test deserialization.
1151                 let features_deserialized = Bolt11InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1152                 assert_eq!(features, features_deserialized);
1153         }
1154
1155         #[test]
1156         fn test_channel_type_mapping() {
1157                 // If we map an Bolt11InvoiceFeatures with StaticRemoteKey optional, it should map into a
1158                 // required-StaticRemoteKey ChannelTypeFeatures.
1159                 let mut init_features = InitFeatures::empty();
1160                 init_features.set_static_remote_key_optional();
1161                 let converted_features = ChannelTypeFeatures::from_init(&init_features);
1162                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1163                 assert!(!converted_features.supports_any_optional_bits());
1164                 assert!(converted_features.requires_static_remote_key());
1165         }
1166 }