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Add an immediately-freeing `MonitorUpdateCompletionAction`.
[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 | Taproot,
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 | Taproot,
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                 Taproot,
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!(31, Taproot, [InitContext, NodeContext, ChannelTypeContext],
398                 "Feature flags for `option_taproot`.", set_taproot_optional,
399                 set_taproot_required, supports_taproot, requires_taproot);
400         define_feature!(39, OnionMessages, [InitContext, NodeContext],
401                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
402                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
403         define_feature!(45, ChannelType, [InitContext, NodeContext],
404                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
405                 set_channel_type_required, supports_channel_type, requires_channel_type);
406         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
407                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
408                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
409         define_feature!(49, PaymentMetadata, [Bolt11InvoiceContext],
410                 "Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
411                 set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
412         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
413                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
414                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
415         define_feature!(55, Keysend, [NodeContext],
416                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
417                 supports_keysend, requires_keysend);
418         // Note: update the module-level docs when a new feature bit is added!
419
420         #[cfg(test)]
421         define_feature!(123456789, UnknownFeature,
422                 [NodeContext, ChannelContext, Bolt11InvoiceContext, OfferContext, InvoiceRequestContext, Bolt12InvoiceContext, BlindedHopContext],
423                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
424                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
425 }
426
427 /// Tracks the set of features which a node implements, templated by the context in which it
428 /// appears.
429 ///
430 /// This is not exported to bindings users as we map the concrete feature types below directly instead
431 #[derive(Eq)]
432 pub struct Features<T: sealed::Context> {
433         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
434         flags: Vec<u8>,
435         mark: PhantomData<T>,
436 }
437
438 impl<T: sealed::Context, Rhs: Borrow<Self>> core::ops::BitOrAssign<Rhs> for Features<T> {
439         fn bitor_assign(&mut self, rhs: Rhs) {
440                 let total_feature_len = cmp::max(self.flags.len(), rhs.borrow().flags.len());
441                 self.flags.resize(total_feature_len, 0u8);
442                 for (byte, rhs_byte) in self.flags.iter_mut().zip(rhs.borrow().flags.iter()) {
443                         *byte |= *rhs_byte;
444                 }
445         }
446 }
447
448 impl<T: sealed::Context> core::ops::BitOr for Features<T> {
449         type Output = Self;
450
451         fn bitor(mut self, o: Self) -> Self {
452                 self |= o;
453                 self
454         }
455 }
456
457 impl<T: sealed::Context> Clone for Features<T> {
458         fn clone(&self) -> Self {
459                 Self {
460                         flags: self.flags.clone(),
461                         mark: PhantomData,
462                 }
463         }
464 }
465 impl<T: sealed::Context> Hash for Features<T> {
466         fn hash<H: Hasher>(&self, hasher: &mut H) {
467                 self.flags.hash(hasher);
468         }
469 }
470 impl<T: sealed::Context> PartialEq for Features<T> {
471         fn eq(&self, o: &Self) -> bool {
472                 self.flags.eq(&o.flags)
473         }
474 }
475 impl<T: sealed::Context> PartialOrd for Features<T> {
476         fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
477                 self.flags.partial_cmp(&other.flags)
478         }
479 }
480 impl<T: sealed::Context + Eq> Ord for Features<T> {
481         fn cmp(&self, other: &Self) -> cmp::Ordering {
482                 self.flags.cmp(&other.flags)
483         }
484 }
485 impl<T: sealed::Context> fmt::Debug for Features<T> {
486         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
487                 self.flags.fmt(fmt)
488         }
489 }
490
491 /// Features used within an `init` message.
492 pub type InitFeatures = Features<sealed::InitContext>;
493 /// Features used within a `node_announcement` message.
494 pub type NodeFeatures = Features<sealed::NodeContext>;
495 /// Features used within a `channel_announcement` message.
496 pub type ChannelFeatures = Features<sealed::ChannelContext>;
497 /// Features used within an invoice.
498 pub type Bolt11InvoiceFeatures = Features<sealed::Bolt11InvoiceContext>;
499 /// Features used within an `offer`.
500 pub type OfferFeatures = Features<sealed::OfferContext>;
501 /// Features used within an `invoice_request`.
502 pub type InvoiceRequestFeatures = Features<sealed::InvoiceRequestContext>;
503 /// Features used within an `invoice`.
504 pub type Bolt12InvoiceFeatures = Features<sealed::Bolt12InvoiceContext>;
505 /// Features used within BOLT 4 encrypted_data_tlv and BOLT 12 blinded_payinfo
506 pub type BlindedHopFeatures = Features<sealed::BlindedHopContext>;
507
508 /// Features used within the channel_type field in an OpenChannel message.
509 ///
510 /// A channel is always of some known "type", describing the transaction formats used and the exact
511 /// semantics of our interaction with our peer.
512 ///
513 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
514 /// the counterparty, only required features are allowed here.
515 ///
516 /// This is serialized differently from other feature types - it is not prefixed by a length, and
517 /// thus must only appear inside a TLV where its length is known in advance.
518 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
519
520 impl InitFeatures {
521         /// Writes all features present up to, and including, 13.
522         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
523                 let len = cmp::min(2, self.flags.len());
524                 (len as u16).write(w)?;
525                 for i in (0..len).rev() {
526                         if i == 0 {
527                                 self.flags[i].write(w)?;
528                         } else {
529                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
530                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
531                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
532                         }
533                 }
534                 Ok(())
535         }
536
537         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
538         /// are included in the result.
539         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
540                 self.to_context_internal()
541         }
542 }
543
544 impl Bolt11InvoiceFeatures {
545         /// Converts `Bolt11InvoiceFeatures` to `Features<C>`. Only known `Bolt11InvoiceFeatures` relevant to
546         /// context `C` are included in the result.
547         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
548                 self.to_context_internal()
549         }
550
551         /// Getting a route for a keysend payment to a private node requires providing the payee's
552         /// features (since they were not announced in a node announcement). However, keysend payments
553         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
554         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
555         /// `Bolt11InvoiceFeatures` for [`find_route`].
556         ///
557         /// MPP keysend is not widely supported yet, so we parameterize support to allow the user to
558         /// choose whether their router should find multi-part routes.
559         ///
560         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
561         /// [`find_route`]: crate::routing::router::find_route
562         pub(crate) fn for_keysend(allow_mpp: bool) -> Bolt11InvoiceFeatures {
563                 let mut res = Bolt11InvoiceFeatures::empty();
564                 res.set_variable_length_onion_optional();
565                 if allow_mpp {
566                         res.set_basic_mpp_optional();
567                 }
568                 res
569         }
570 }
571
572 impl Bolt12InvoiceFeatures {
573         /// Converts [`Bolt12InvoiceFeatures`] to [`Features<C>`]. Only known [`Bolt12InvoiceFeatures`]
574         /// relevant to context `C` are included in the result.
575         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
576                 self.to_context_internal()
577         }
578 }
579
580 impl ChannelTypeFeatures {
581         // Maps the relevant `InitFeatures` to `ChannelTypeFeatures`. Any unknown features to
582         // `ChannelTypeFeatures` are not included in the result.
583         pub(crate) fn from_init(init: &InitFeatures) -> Self {
584                 let mut ret = init.to_context_internal();
585                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
586                 // optional bits and then AND out the optional ones.
587                 for byte in ret.flags.iter_mut() {
588                         *byte |= (*byte & 0b10_10_10_10) >> 1;
589                         *byte &= 0b01_01_01_01;
590                 }
591                 ret
592         }
593
594         /// Constructs a ChannelTypeFeatures with only static_remotekey set
595         pub(crate) fn only_static_remote_key() -> Self {
596                 let mut ret = Self::empty();
597                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
598                 ret
599         }
600
601         /// Constructs a ChannelTypeFeatures with anchors support
602         pub(crate) fn anchors_zero_htlc_fee_and_dependencies() -> Self {
603                 let mut ret = Self::empty();
604                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
605                 <sealed::ChannelTypeContext as sealed::AnchorsZeroFeeHtlcTx>::set_required_bit(&mut ret.flags);
606                 ret
607         }
608 }
609
610 impl ToBase32 for Bolt11InvoiceFeatures {
611         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
612                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
613                 // minus one before dividing
614                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
615                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
616                 for (byte_idx, byte) in self.flags.iter().enumerate() {
617                         let bit_pos_from_left_0_indexed = byte_idx * 8;
618                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
619                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
620                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
621                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
622                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
623                         if new_u5_idx > 0 {
624                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
625                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
626                         }
627                         if new_u5_idx > 1 {
628                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
629                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
630                         }
631                 }
632                 // Trim the highest feature bits.
633                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
634                         res_u5s.remove(0);
635                 }
636                 writer.write(&res_u5s)
637         }
638 }
639
640 impl Base32Len for Bolt11InvoiceFeatures {
641         fn base32_len(&self) -> usize {
642                 self.to_base32().len()
643         }
644 }
645
646 impl FromBase32 for Bolt11InvoiceFeatures {
647         type Err = bech32::Error;
648
649         fn from_base32(field_data: &[u5]) -> Result<Bolt11InvoiceFeatures, bech32::Error> {
650                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
651                 // minus one before dividing
652                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
653                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
654                 for (u5_idx, chunk) in field_data.iter().enumerate() {
655                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
656                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
657                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
658                         let chunk_u16 = chunk.to_u8() as u16;
659                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
660                         if new_byte_idx != length_bytes - 1 {
661                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
662                         }
663                 }
664                 // Trim the highest feature bits.
665                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
666                         res_bytes.pop();
667                 }
668                 Ok(Bolt11InvoiceFeatures::from_le_bytes(res_bytes))
669         }
670 }
671
672 impl<T: sealed::Context> Features<T> {
673         /// Create a blank Features with no features set
674         pub fn empty() -> Self {
675                 Features {
676                         flags: Vec::new(),
677                         mark: PhantomData,
678                 }
679         }
680
681         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
682         /// included in the result.
683         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
684                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
685                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
686                 let mut flags = Vec::new();
687                 for (i, byte) in self.flags.iter().enumerate() {
688                         if i < from_byte_count && i < to_byte_count {
689                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
690                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
691                                 flags.push(byte & from_known_features & to_known_features);
692                         }
693                 }
694                 Features::<C> { flags, mark: PhantomData, }
695         }
696
697         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
698         /// most on-the-wire encodings.
699         ///
700         /// This is not exported to bindings users as we don't support export across multiple T
701         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
702                 Features {
703                         flags,
704                         mark: PhantomData,
705                 }
706         }
707
708         #[cfg(test)]
709         /// Gets the underlying flags set, in LE.
710         pub fn le_flags(&self) -> &Vec<u8> {
711                 &self.flags
712         }
713
714         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
715                 for f in self.flags.iter().rev() { // Swap back to big-endian
716                         f.write(w)?;
717                 }
718                 Ok(())
719         }
720
721         /// Create a [`Features`] given a set of flags, in big-endian. This is in byte order from
722         /// most on-the-wire encodings.
723         ///
724         /// This is not exported to bindings users as we don't support export across multiple T
725         pub fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
726                 flags.reverse(); // Swap to little-endian
727                 Self {
728                         flags,
729                         mark: PhantomData,
730                 }
731         }
732
733         pub(crate) fn supports_any_optional_bits(&self) -> bool {
734                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
735         }
736
737         /// Returns true if this `Features` object contains required features unknown by `other`.
738         pub fn requires_unknown_bits_from(&self, other: &Self) -> bool {
739                 // Bitwise AND-ing with all even bits set except for known features will select required
740                 // unknown features.
741                 self.flags.iter().enumerate().any(|(i, &byte)| {
742                         const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
743                         const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
744                         let unknown_features = if i < other.flags.len() {
745                                 // Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
746                                 !(other.flags[i]
747                                         | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
748                                         | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
749                         } else {
750                                 0b11_11_11_11
751                         };
752                         (byte & (REQUIRED_FEATURES & unknown_features)) != 0
753                 })
754         }
755
756         /// Returns true if this `Features` object contains unknown feature flags which are set as
757         /// "required".
758         pub fn requires_unknown_bits(&self) -> bool {
759                 // Bitwise AND-ing with all even bits set except for known features will select required
760                 // unknown features.
761                 let byte_count = T::KNOWN_FEATURE_MASK.len();
762                 self.flags.iter().enumerate().any(|(i, &byte)| {
763                         let required_features = 0b01_01_01_01;
764                         let unknown_features = if i < byte_count {
765                                 !T::KNOWN_FEATURE_MASK[i]
766                         } else {
767                                 0b11_11_11_11
768                         };
769                         (byte & (required_features & unknown_features)) != 0
770                 })
771         }
772
773         pub(crate) fn supports_unknown_bits(&self) -> bool {
774                 // Bitwise AND-ing with all even and odd bits set except for known features will select
775                 // both required and optional unknown features.
776                 let byte_count = T::KNOWN_FEATURE_MASK.len();
777                 self.flags.iter().enumerate().any(|(i, &byte)| {
778                         let unknown_features = if i < byte_count {
779                                 !T::KNOWN_FEATURE_MASK[i]
780                         } else {
781                                 0b11_11_11_11
782                         };
783                         (byte & unknown_features) != 0
784                 })
785         }
786
787         // Returns true if the features within `self` are a subset of the features within `other`.
788         pub(crate) fn is_subset(&self, other: &Self) -> bool {
789                 for (idx, byte) in self.flags.iter().enumerate() {
790                         if let Some(other_byte) = other.flags.get(idx) {
791                                 if byte & other_byte != *byte {
792                                         // `self` has bits set that `other` doesn't.
793                                         return false;
794                                 }
795                         } else {
796                                 if *byte > 0 {
797                                         // `self` has a non-zero byte that `other` doesn't.
798                                         return false;
799                                 }
800                         }
801                 }
802                 true
803         }
804
805         /// Sets a required feature bit. Errors if `bit` is outside the feature range as defined
806         /// by [BOLT 9].
807         ///
808         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
809         /// be set instead (i.e., `bit - 1`).
810         ///
811         /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
812         pub fn set_required_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
813                 self.set_feature_bit(bit - (bit % 2))
814         }
815
816         /// Sets an optional feature bit. Errors if `bit` is outside the feature range as defined
817         /// by [BOLT 9].
818         ///
819         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
820         /// set instead (i.e., `bit + 1`).
821         ///
822         /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
823         pub fn set_optional_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
824                 self.set_feature_bit(bit + (1 - (bit % 2)))
825         }
826
827         fn set_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
828                 if bit > 255 {
829                         return Err(());
830                 }
831                 self.set_bit(bit, false)
832         }
833
834         /// Sets a required custom feature bit. Errors if `bit` is outside the custom range as defined
835         /// by [bLIP 2] or if it is a known `T` feature.
836         ///
837         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
838         /// be set instead (i.e., `bit - 1`).
839         ///
840         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
841         pub fn set_required_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
842                 self.set_custom_bit(bit - (bit % 2))
843         }
844
845         /// Sets an optional custom feature bit. Errors if `bit` is outside the custom range as defined
846         /// by [bLIP 2] or if it is a known `T` feature.
847         ///
848         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
849         /// set instead (i.e., `bit + 1`).
850         ///
851         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
852         pub fn set_optional_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
853                 self.set_custom_bit(bit + (1 - (bit % 2)))
854         }
855
856         fn set_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
857                 if bit < 256 {
858                         return Err(());
859                 }
860                 self.set_bit(bit, true)
861         }
862
863         fn set_bit(&mut self, bit: usize, custom: bool) -> Result<(), ()> {
864                 let byte_offset = bit / 8;
865                 let mask = 1 << (bit - 8 * byte_offset);
866                 if byte_offset < T::KNOWN_FEATURE_MASK.len() && custom {
867                         if (T::KNOWN_FEATURE_MASK[byte_offset] & mask) != 0 {
868                                 return Err(());
869                         }
870                 }
871
872                 if self.flags.len() <= byte_offset {
873                         self.flags.resize(byte_offset + 1, 0u8);
874                 }
875
876                 self.flags[byte_offset] |= mask;
877
878                 Ok(())
879         }
880 }
881
882 impl<T: sealed::UpfrontShutdownScript> Features<T> {
883         #[cfg(test)]
884         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
885                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
886                 self
887         }
888 }
889
890 impl<T: sealed::ShutdownAnySegwit> Features<T> {
891         #[cfg(test)]
892         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
893                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
894                 self
895         }
896 }
897
898 impl<T: sealed::Wumbo> Features<T> {
899         #[cfg(test)]
900         pub(crate) fn clear_wumbo(mut self) -> Self {
901                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
902                 self
903         }
904 }
905
906 impl<T: sealed::SCIDPrivacy> Features<T> {
907         pub(crate) fn clear_scid_privacy(&mut self) {
908                 <T as sealed::SCIDPrivacy>::clear_bits(&mut self.flags);
909         }
910 }
911
912 impl<T: sealed::AnchorsZeroFeeHtlcTx> Features<T> {
913         pub(crate) fn clear_anchors_zero_fee_htlc_tx(&mut self) {
914                 <T as sealed::AnchorsZeroFeeHtlcTx>::clear_bits(&mut self.flags);
915         }
916 }
917
918 #[cfg(test)]
919 impl<T: sealed::UnknownFeature> Features<T> {
920         pub(crate) fn unknown() -> Self {
921                 let mut features = Self::empty();
922                 features.set_unknown_feature_required();
923                 features
924         }
925 }
926
927 macro_rules! impl_feature_len_prefixed_write {
928         ($features: ident) => {
929                 impl Writeable for $features {
930                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
931                                 (self.flags.len() as u16).write(w)?;
932                                 self.write_be(w)
933                         }
934                 }
935                 impl Readable for $features {
936                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
937                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
938                         }
939                 }
940         }
941 }
942 impl_feature_len_prefixed_write!(InitFeatures);
943 impl_feature_len_prefixed_write!(ChannelFeatures);
944 impl_feature_len_prefixed_write!(NodeFeatures);
945 impl_feature_len_prefixed_write!(Bolt11InvoiceFeatures);
946 impl_feature_len_prefixed_write!(Bolt12InvoiceFeatures);
947 impl_feature_len_prefixed_write!(BlindedHopFeatures);
948
949 // Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
950 macro_rules! impl_feature_tlv_write {
951         ($features: ident) => {
952                 impl Writeable for $features {
953                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
954                                 WithoutLength(self).write(w)
955                         }
956                 }
957                 impl Readable for $features {
958                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
959                                 Ok(WithoutLength::<Self>::read(r)?.0)
960                         }
961                 }
962         }
963 }
964
965 impl_feature_tlv_write!(ChannelTypeFeatures);
966
967 // Some features may appear both in a TLV record and as part of a TLV subtype sequence. The latter
968 // requires a length but the former does not.
969
970 impl<T: sealed::Context> Writeable for WithoutLength<&Features<T>> {
971         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
972                 self.0.write_be(w)
973         }
974 }
975
976 impl<T: sealed::Context> Readable for WithoutLength<Features<T>> {
977         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
978                 let v = io_extras::read_to_end(r)?;
979                 Ok(WithoutLength(Features::<T>::from_be_bytes(v)))
980         }
981 }
982
983 #[cfg(test)]
984 mod tests {
985         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, Bolt11InvoiceFeatures, NodeFeatures, OfferFeatures, sealed};
986         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
987         use crate::util::ser::{Readable, WithoutLength, Writeable};
988
989         #[test]
990         fn sanity_test_unknown_bits() {
991                 let features = ChannelFeatures::empty();
992                 assert!(!features.requires_unknown_bits());
993                 assert!(!features.supports_unknown_bits());
994
995                 let mut features = ChannelFeatures::empty();
996                 features.set_unknown_feature_required();
997                 assert!(features.requires_unknown_bits());
998                 assert!(features.supports_unknown_bits());
999
1000                 let mut features = ChannelFeatures::empty();
1001                 features.set_unknown_feature_optional();
1002                 assert!(!features.requires_unknown_bits());
1003                 assert!(features.supports_unknown_bits());
1004         }
1005
1006         #[test]
1007         fn requires_unknown_bits_from() {
1008                 let mut features1 = InitFeatures::empty();
1009                 let mut features2 = InitFeatures::empty();
1010                 assert!(!features1.requires_unknown_bits_from(&features2));
1011                 assert!(!features2.requires_unknown_bits_from(&features1));
1012
1013                 features1.set_data_loss_protect_required();
1014                 assert!(features1.requires_unknown_bits_from(&features2));
1015                 assert!(!features2.requires_unknown_bits_from(&features1));
1016
1017                 features2.set_data_loss_protect_optional();
1018                 assert!(!features1.requires_unknown_bits_from(&features2));
1019                 assert!(!features2.requires_unknown_bits_from(&features1));
1020
1021                 features2.set_gossip_queries_required();
1022                 assert!(!features1.requires_unknown_bits_from(&features2));
1023                 assert!(features2.requires_unknown_bits_from(&features1));
1024
1025                 features1.set_gossip_queries_optional();
1026                 assert!(!features1.requires_unknown_bits_from(&features2));
1027                 assert!(!features2.requires_unknown_bits_from(&features1));
1028
1029                 features1.set_variable_length_onion_required();
1030                 assert!(features1.requires_unknown_bits_from(&features2));
1031                 assert!(!features2.requires_unknown_bits_from(&features1));
1032
1033                 features2.set_variable_length_onion_optional();
1034                 assert!(!features1.requires_unknown_bits_from(&features2));
1035                 assert!(!features2.requires_unknown_bits_from(&features1));
1036
1037                 features1.set_basic_mpp_required();
1038                 features2.set_wumbo_required();
1039                 assert!(features1.requires_unknown_bits_from(&features2));
1040                 assert!(features2.requires_unknown_bits_from(&features1));
1041         }
1042
1043         #[test]
1044         fn convert_to_context_with_relevant_flags() {
1045                 let mut init_features = InitFeatures::empty();
1046                 // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
1047                 // converted as it's only relevant in an init context).
1048                 init_features.set_initial_routing_sync_required();
1049                 init_features.set_data_loss_protect_required();
1050                 init_features.set_variable_length_onion_required();
1051                 init_features.set_static_remote_key_required();
1052                 init_features.set_payment_secret_required();
1053                 init_features.set_basic_mpp_optional();
1054                 init_features.set_wumbo_optional();
1055                 init_features.set_anchors_zero_fee_htlc_tx_optional();
1056                 init_features.set_shutdown_any_segwit_optional();
1057                 init_features.set_onion_messages_optional();
1058                 init_features.set_channel_type_optional();
1059                 init_features.set_scid_privacy_optional();
1060                 init_features.set_zero_conf_optional();
1061
1062                 assert!(init_features.initial_routing_sync());
1063                 assert!(!init_features.supports_upfront_shutdown_script());
1064                 assert!(!init_features.supports_gossip_queries());
1065
1066                 let node_features: NodeFeatures = init_features.to_context();
1067                 {
1068                         // Check that the flags are as expected:
1069                         // - option_data_loss_protect (req)
1070                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
1071                         // - basic_mpp | wumbo | anchors_zero_fee_htlc_tx
1072                         // - opt_shutdown_anysegwit
1073                         // - onion_messages
1074                         // - option_channel_type | option_scid_alias
1075                         // - option_zeroconf
1076                         assert_eq!(node_features.flags.len(), 7);
1077                         assert_eq!(node_features.flags[0], 0b00000001);
1078                         assert_eq!(node_features.flags[1], 0b01010001);
1079                         assert_eq!(node_features.flags[2], 0b10001010);
1080                         assert_eq!(node_features.flags[3], 0b00001000);
1081                         assert_eq!(node_features.flags[4], 0b10000000);
1082                         assert_eq!(node_features.flags[5], 0b10100000);
1083                         assert_eq!(node_features.flags[6], 0b00001000);
1084                 }
1085
1086                 // Check that cleared flags are kept blank when converting back:
1087                 // - initial_routing_sync was not applicable to NodeContext
1088                 // - upfront_shutdown_script was cleared before converting
1089                 // - gossip_queries was cleared before converting
1090                 let features: InitFeatures = node_features.to_context_internal();
1091                 assert!(!features.initial_routing_sync());
1092                 assert!(!features.supports_upfront_shutdown_script());
1093                 assert!(!init_features.supports_gossip_queries());
1094         }
1095
1096         #[test]
1097         fn convert_to_context_with_unknown_flags() {
1098                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1099                 assert!(<sealed::ChannelContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
1100                         <sealed::Bolt11InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
1101                 let mut channel_features = ChannelFeatures::empty();
1102                 channel_features.set_unknown_feature_optional();
1103                 assert!(channel_features.supports_unknown_bits());
1104                 let invoice_features: Bolt11InvoiceFeatures = channel_features.to_context_internal();
1105                 assert!(!invoice_features.supports_unknown_bits());
1106         }
1107
1108         #[test]
1109         fn set_feature_bits() {
1110                 let mut features = Bolt11InvoiceFeatures::empty();
1111                 features.set_basic_mpp_optional();
1112                 features.set_payment_secret_required();
1113                 assert!(features.supports_basic_mpp());
1114                 assert!(!features.requires_basic_mpp());
1115                 assert!(features.requires_payment_secret());
1116                 assert!(features.supports_payment_secret());
1117
1118                 // Set flags manually
1119                 let mut features = NodeFeatures::empty();
1120                 assert!(features.set_optional_feature_bit(55).is_ok());
1121                 assert!(features.supports_keysend());
1122                 assert!(features.set_optional_feature_bit(255).is_ok());
1123                 assert!(features.set_required_feature_bit(256).is_err());
1124         }
1125
1126         #[test]
1127         fn set_custom_bits() {
1128                 let mut features = Bolt11InvoiceFeatures::empty();
1129                 features.set_variable_length_onion_optional();
1130                 assert_eq!(features.flags[1], 0b00000010);
1131
1132                 assert!(features.set_optional_custom_bit(255).is_err());
1133                 assert!(features.set_required_custom_bit(256).is_ok());
1134                 assert!(features.set_required_custom_bit(258).is_ok());
1135                 assert_eq!(features.flags[31], 0b00000000);
1136                 assert_eq!(features.flags[32], 0b00000101);
1137
1138                 let known_bit = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::EVEN_BIT;
1139                 let byte_offset = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::BYTE_OFFSET;
1140                 assert_eq!(byte_offset, 1);
1141                 assert_eq!(features.flags[byte_offset], 0b00000010);
1142                 assert!(features.set_required_custom_bit(known_bit).is_err());
1143                 assert_eq!(features.flags[byte_offset], 0b00000010);
1144
1145                 let mut features = Bolt11InvoiceFeatures::empty();
1146                 assert!(features.set_optional_custom_bit(256).is_ok());
1147                 assert!(features.set_optional_custom_bit(259).is_ok());
1148                 assert_eq!(features.flags[32], 0b00001010);
1149
1150                 let mut features = Bolt11InvoiceFeatures::empty();
1151                 assert!(features.set_required_custom_bit(257).is_ok());
1152                 assert!(features.set_required_custom_bit(258).is_ok());
1153                 assert_eq!(features.flags[32], 0b00000101);
1154         }
1155
1156         #[test]
1157         fn encodes_features_without_length() {
1158                 let features = OfferFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1159                 assert_eq!(features.flags.len(), 8);
1160
1161                 let mut serialized_features = Vec::new();
1162                 WithoutLength(&features).write(&mut serialized_features).unwrap();
1163                 assert_eq!(serialized_features.len(), 8);
1164
1165                 let deserialized_features =
1166                         WithoutLength::<OfferFeatures>::read(&mut &serialized_features[..]).unwrap().0;
1167                 assert_eq!(features, deserialized_features);
1168         }
1169
1170         #[test]
1171         fn invoice_features_encoding() {
1172                 let features_as_u5s = vec![
1173                         u5::try_from_u8(6).unwrap(),
1174                         u5::try_from_u8(10).unwrap(),
1175                         u5::try_from_u8(25).unwrap(),
1176                         u5::try_from_u8(1).unwrap(),
1177                         u5::try_from_u8(10).unwrap(),
1178                         u5::try_from_u8(0).unwrap(),
1179                         u5::try_from_u8(20).unwrap(),
1180                         u5::try_from_u8(2).unwrap(),
1181                         u5::try_from_u8(0).unwrap(),
1182                         u5::try_from_u8(6).unwrap(),
1183                         u5::try_from_u8(0).unwrap(),
1184                         u5::try_from_u8(16).unwrap(),
1185                         u5::try_from_u8(1).unwrap(),
1186                 ];
1187                 let features = Bolt11InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1188
1189                 // Test length calculation.
1190                 assert_eq!(features.base32_len(), 13);
1191
1192                 // Test serialization.
1193                 let features_serialized = features.to_base32();
1194                 assert_eq!(features_as_u5s, features_serialized);
1195
1196                 // Test deserialization.
1197                 let features_deserialized = Bolt11InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1198                 assert_eq!(features, features_deserialized);
1199         }
1200
1201         #[test]
1202         fn test_channel_type_mapping() {
1203                 // If we map an Bolt11InvoiceFeatures with StaticRemoteKey optional, it should map into a
1204                 // required-StaticRemoteKey ChannelTypeFeatures.
1205                 let mut init_features = InitFeatures::empty();
1206                 init_features.set_static_remote_key_optional();
1207                 let converted_features = ChannelTypeFeatures::from_init(&init_features);
1208                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1209                 assert!(!converted_features.supports_any_optional_bits());
1210                 assert!(converted_features.requires_static_remote_key());
1211         }
1212 }