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Merge pull request #2226 from alecchendev/2023-04-persist-network-graph-on-rgs
[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 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
69 //! [messages]: crate::ln::msgs
70
71 use crate::{io, io_extras};
72 use crate::prelude::*;
73 use core::{cmp, fmt};
74 use core::hash::{Hash, Hasher};
75 use core::marker::PhantomData;
76
77 use bitcoin::bech32;
78 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
79 use crate::ln::msgs::DecodeError;
80 use crate::util::ser::{Readable, WithoutLength, Writeable, Writer};
81
82 mod sealed {
83         use crate::prelude::*;
84         use crate::ln::features::Features;
85
86         /// The context in which [`Features`] are applicable. Defines which features are known to the
87         /// implementation, though specification of them as required or optional is up to the code
88         /// constructing a features object.
89         pub trait Context {
90                 /// Bitmask for selecting features that are known to the implementation.
91                 const KNOWN_FEATURE_MASK: &'static [u8];
92         }
93
94         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
95         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
96         /// feature identifiers.
97         macro_rules! define_context {
98                 ($context: ident, [$( $( $known_feature: ident )|*, )*]) => {
99                         #[derive(Eq, PartialEq)]
100                         pub struct $context {}
101
102                         impl Context for $context {
103                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
104                                         $(
105                                                 0b00_00_00_00 $(|
106                                                         <Self as $known_feature>::REQUIRED_MASK |
107                                                         <Self as $known_feature>::OPTIONAL_MASK)*,
108                                         )*
109                                 ];
110                         }
111
112                         impl alloc::fmt::Display for Features<$context> {
113                                 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
114                                         $(
115                                                 $(
116                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($known_feature),
117                                                                 if <$context as $known_feature>::requires_feature(&self.flags) { "required" }
118                                                                 else if <$context as $known_feature>::supports_feature(&self.flags) { "supported" }
119                                                                 else { "not supported" }))?;
120                                                 )*
121                                                 {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
122                                         )*
123                                         fmt.write_fmt(format_args!("unknown flags: {}",
124                                                 if self.requires_unknown_bits() { "required" }
125                                                 else if self.supports_unknown_bits() { "supported" } else { "none" }))
126                                 }
127                         }
128                 };
129         }
130
131         define_context!(InitContext, [
132                 // Byte 0
133                 DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
134                 // Byte 1
135                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
136                 // Byte 2
137                 BasicMPP | Wumbo | AnchorsZeroFeeHtlcTx,
138                 // Byte 3
139                 ShutdownAnySegwit,
140                 // Byte 4
141                 OnionMessages,
142                 // Byte 5
143                 ChannelType | SCIDPrivacy,
144                 // Byte 6
145                 ZeroConf,
146         ]);
147         define_context!(NodeContext, [
148                 // Byte 0
149                 DataLossProtect | UpfrontShutdownScript | GossipQueries,
150                 // Byte 1
151                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
152                 // Byte 2
153                 BasicMPP | Wumbo | AnchorsZeroFeeHtlcTx,
154                 // Byte 3
155                 ShutdownAnySegwit,
156                 // Byte 4
157                 OnionMessages,
158                 // Byte 5
159                 ChannelType | SCIDPrivacy,
160                 // Byte 6
161                 ZeroConf | Keysend,
162         ]);
163         define_context!(ChannelContext, []);
164         define_context!(InvoiceContext, [
165                 // Byte 0
166                 ,
167                 // Byte 1
168                 VariableLengthOnion | PaymentSecret,
169                 // Byte 2
170                 BasicMPP,
171                 // Byte 3
172                 ,
173                 // Byte 4
174                 ,
175                 // Byte 5
176                 ,
177                 // Byte 6
178                 PaymentMetadata,
179         ]);
180         define_context!(OfferContext, []);
181         define_context!(InvoiceRequestContext, []);
182         define_context!(Bolt12InvoiceContext, [
183                 // Byte 0
184                 ,
185                 // Byte 1
186                 ,
187                 // Byte 2
188                 BasicMPP,
189         ]);
190         define_context!(BlindedHopContext, []);
191         // This isn't a "real" feature context, and is only used in the channel_type field in an
192         // `OpenChannel` message.
193         define_context!(ChannelTypeContext, [
194                 // Byte 0
195                 ,
196                 // Byte 1
197                 StaticRemoteKey,
198                 // Byte 2
199                 AnchorsZeroFeeHtlcTx,
200                 // Byte 3
201                 ,
202                 // Byte 4
203                 ,
204                 // Byte 5
205                 SCIDPrivacy,
206                 // Byte 6
207                 ZeroConf,
208         ]);
209
210         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
211         /// useful for manipulating feature flags.
212         macro_rules! define_feature {
213                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
214                  $required_setter: ident, $supported_getter: ident) => {
215                         #[doc = $doc]
216                         ///
217                         /// See [BOLT #9] for details.
218                         ///
219                         /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
220                         pub trait $feature: Context {
221                                 /// The bit used to signify that the feature is required.
222                                 const EVEN_BIT: usize = $odd_bit - 1;
223
224                                 /// The bit used to signify that the feature is optional.
225                                 const ODD_BIT: usize = $odd_bit;
226
227                                 /// Assertion that [`EVEN_BIT`] is actually even.
228                                 ///
229                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
230                                 const ASSERT_EVEN_BIT_PARITY: usize;
231
232                                 /// Assertion that [`ODD_BIT`] is actually odd.
233                                 ///
234                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
235                                 const ASSERT_ODD_BIT_PARITY: usize;
236
237                                 /// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
238                                 ///
239                                 /// [`KNOWN_FEATURE_MASK`]: Context::KNOWN_FEATURE_MASK
240                                 #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
241                                 const ASSERT_BITS_IN_MASK: u8;
242
243                                 /// The byte where the feature is set.
244                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
245
246                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
247                                 ///
248                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
249                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
250
251                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
252                                 ///
253                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
254                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
255
256                                 /// Returns whether the feature is required by the given flags.
257                                 #[inline]
258                                 fn requires_feature(flags: &Vec<u8>) -> bool {
259                                         flags.len() > Self::BYTE_OFFSET &&
260                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
261                                 }
262
263                                 /// Returns whether the feature is supported by the given flags.
264                                 #[inline]
265                                 fn supports_feature(flags: &Vec<u8>) -> bool {
266                                         flags.len() > Self::BYTE_OFFSET &&
267                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
268                                 }
269
270                                 /// Sets the feature's required (even) bit in the given flags.
271                                 #[inline]
272                                 fn set_required_bit(flags: &mut Vec<u8>) {
273                                         if flags.len() <= Self::BYTE_OFFSET {
274                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
275                                         }
276
277                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
278                                         flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
279                                 }
280
281                                 /// Sets the feature's optional (odd) bit in the given flags.
282                                 #[inline]
283                                 fn set_optional_bit(flags: &mut Vec<u8>) {
284                                         if flags.len() <= Self::BYTE_OFFSET {
285                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
286                                         }
287
288                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
289                                 }
290
291                                 /// Clears the feature's required (even) and optional (odd) bits from the given
292                                 /// flags.
293                                 #[inline]
294                                 fn clear_bits(flags: &mut Vec<u8>) {
295                                         if flags.len() > Self::BYTE_OFFSET {
296                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
297                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
298                                         }
299
300                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
301                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
302                                         flags.resize(size, 0u8);
303                                 }
304                         }
305
306                         impl <T: $feature> Features<T> {
307                                 /// Set this feature as optional.
308                                 pub fn $optional_setter(&mut self) {
309                                         <T as $feature>::set_optional_bit(&mut self.flags);
310                                 }
311
312                                 /// Set this feature as required.
313                                 pub fn $required_setter(&mut self) {
314                                         <T as $feature>::set_required_bit(&mut self.flags);
315                                 }
316
317                                 /// Checks if this feature is supported.
318                                 pub fn $supported_getter(&self) -> bool {
319                                         <T as $feature>::supports_feature(&self.flags)
320                                 }
321                         }
322
323                         $(
324                                 impl $feature for $context {
325                                         // EVEN_BIT % 2 == 0
326                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
327
328                                         // ODD_BIT % 2 == 1
329                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
330
331                                         // (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
332                                         #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
333                                         const ASSERT_BITS_IN_MASK: u8 =
334                                                 ((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
335                                                  >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
336                                 }
337                         )*
338                 };
339                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
340                  $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
341                         define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
342                         impl <T: $feature> Features<T> {
343                                 /// Checks if this feature is required.
344                                 pub fn $required_getter(&self) -> bool {
345                                         <T as $feature>::requires_feature(&self.flags)
346                                 }
347                         }
348                 }
349         }
350
351         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
352                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
353                 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
354         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
355         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
356                 set_initial_routing_sync_optional, set_initial_routing_sync_required,
357                 initial_routing_sync);
358         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
359                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
360                 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
361                 requires_upfront_shutdown_script);
362         define_feature!(7, GossipQueries, [InitContext, NodeContext],
363                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
364                 supports_gossip_queries, requires_gossip_queries);
365         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
366                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
367                 set_variable_length_onion_required, supports_variable_length_onion,
368                 requires_variable_length_onion);
369         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
370                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
371                 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
372         define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
373                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
374                 supports_payment_secret, requires_payment_secret);
375         define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext, Bolt12InvoiceContext],
376                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
377                 supports_basic_mpp, requires_basic_mpp);
378         define_feature!(19, Wumbo, [InitContext, NodeContext],
379                 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
380                 supports_wumbo, requires_wumbo);
381         define_feature!(23, AnchorsZeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
382                 "Feature flags for `option_anchors_zero_fee_htlc_tx`.", set_anchors_zero_fee_htlc_tx_optional,
383                 set_anchors_zero_fee_htlc_tx_required, supports_anchors_zero_fee_htlc_tx, requires_anchors_zero_fee_htlc_tx);
384         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
385                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
386                 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
387         define_feature!(39, OnionMessages, [InitContext, NodeContext],
388                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
389                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
390         define_feature!(45, ChannelType, [InitContext, NodeContext],
391                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
392                 set_channel_type_required, supports_channel_type, requires_channel_type);
393         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
394                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
395                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
396         define_feature!(49, PaymentMetadata, [InvoiceContext],
397                 "Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
398                 set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
399         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
400                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
401                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
402         define_feature!(55, Keysend, [NodeContext],
403                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
404                 supports_keysend, requires_keysend);
405         // Note: update the module-level docs when a new feature bit is added!
406
407         #[cfg(test)]
408         define_feature!(123456789, UnknownFeature,
409                 [NodeContext, ChannelContext, InvoiceContext, OfferContext, InvoiceRequestContext, Bolt12InvoiceContext, BlindedHopContext],
410                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
411                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
412 }
413
414 /// Tracks the set of features which a node implements, templated by the context in which it
415 /// appears.
416 ///
417 /// This is not exported to bindings users as we map the concrete feature types below directly instead
418 #[derive(Eq)]
419 pub struct Features<T: sealed::Context> {
420         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
421         flags: Vec<u8>,
422         mark: PhantomData<T>,
423 }
424
425 impl<T: sealed::Context> core::ops::BitOr for Features<T> {
426         type Output = Self;
427
428         fn bitor(mut self, o: Self) -> Self {
429                 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
430                 self.flags.resize(total_feature_len, 0u8);
431                 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
432                         *byte |= *o_byte;
433                 }
434                 self
435         }
436 }
437
438 impl<T: sealed::Context> Clone for Features<T> {
439         fn clone(&self) -> Self {
440                 Self {
441                         flags: self.flags.clone(),
442                         mark: PhantomData,
443                 }
444         }
445 }
446 impl<T: sealed::Context> Hash for Features<T> {
447         fn hash<H: Hasher>(&self, hasher: &mut H) {
448                 self.flags.hash(hasher);
449         }
450 }
451 impl<T: sealed::Context> PartialEq for Features<T> {
452         fn eq(&self, o: &Self) -> bool {
453                 self.flags.eq(&o.flags)
454         }
455 }
456 impl<T: sealed::Context> PartialOrd for Features<T> {
457         fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
458                 self.flags.partial_cmp(&other.flags)
459         }
460 }
461 impl<T: sealed::Context + Eq> Ord for Features<T> {
462         fn cmp(&self, other: &Self) -> cmp::Ordering {
463                 self.flags.cmp(&other.flags)
464         }
465 }
466 impl<T: sealed::Context> fmt::Debug for Features<T> {
467         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
468                 self.flags.fmt(fmt)
469         }
470 }
471
472 /// Features used within an `init` message.
473 pub type InitFeatures = Features<sealed::InitContext>;
474 /// Features used within a `node_announcement` message.
475 pub type NodeFeatures = Features<sealed::NodeContext>;
476 /// Features used within a `channel_announcement` message.
477 pub type ChannelFeatures = Features<sealed::ChannelContext>;
478 /// Features used within an invoice.
479 pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
480 /// Features used within an `offer`.
481 pub type OfferFeatures = Features<sealed::OfferContext>;
482 /// Features used within an `invoice_request`.
483 pub type InvoiceRequestFeatures = Features<sealed::InvoiceRequestContext>;
484 /// Features used within an `invoice`.
485 pub type Bolt12InvoiceFeatures = Features<sealed::Bolt12InvoiceContext>;
486 /// Features used within BOLT 4 encrypted_data_tlv and BOLT 12 blinded_payinfo
487 pub type BlindedHopFeatures = Features<sealed::BlindedHopContext>;
488
489 /// Features used within the channel_type field in an OpenChannel message.
490 ///
491 /// A channel is always of some known "type", describing the transaction formats used and the exact
492 /// semantics of our interaction with our peer.
493 ///
494 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
495 /// the counterparty, only required features are allowed here.
496 ///
497 /// This is serialized differently from other feature types - it is not prefixed by a length, and
498 /// thus must only appear inside a TLV where its length is known in advance.
499 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
500
501 impl InitFeatures {
502         /// Writes all features present up to, and including, 13.
503         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
504                 let len = cmp::min(2, self.flags.len());
505                 (len as u16).write(w)?;
506                 for i in (0..len).rev() {
507                         if i == 0 {
508                                 self.flags[i].write(w)?;
509                         } else {
510                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
511                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
512                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
513                         }
514                 }
515                 Ok(())
516         }
517
518         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
519         /// are included in the result.
520         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
521                 self.to_context_internal()
522         }
523 }
524
525 impl InvoiceFeatures {
526         /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
527         /// context `C` are included in the result.
528         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
529                 self.to_context_internal()
530         }
531
532         /// Getting a route for a keysend payment to a private node requires providing the payee's
533         /// features (since they were not announced in a node announcement). However, keysend payments
534         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
535         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
536         /// `InvoiceFeatures` for [`find_route`].
537         ///
538         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
539         /// [`find_route`]: crate::routing::router::find_route
540         pub(crate) fn for_keysend() -> InvoiceFeatures {
541                 let mut res = InvoiceFeatures::empty();
542                 res.set_variable_length_onion_optional();
543                 res
544         }
545 }
546
547 impl Bolt12InvoiceFeatures {
548         /// Converts `Bolt12InvoiceFeatures` to `Features<C>`. Only known `Bolt12InvoiceFeatures` relevant
549         /// to context `C` are included in the result.
550         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
551                 self.to_context_internal()
552         }
553 }
554
555 impl ChannelTypeFeatures {
556         // Maps the relevant `InitFeatures` to `ChannelTypeFeatures`. Any unknown features to
557         // `ChannelTypeFeatures` are not included in the result.
558         pub(crate) fn from_init(init: &InitFeatures) -> Self {
559                 let mut ret = init.to_context_internal();
560                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
561                 // optional bits and then AND out the optional ones.
562                 for byte in ret.flags.iter_mut() {
563                         *byte |= (*byte & 0b10_10_10_10) >> 1;
564                         *byte &= 0b01_01_01_01;
565                 }
566                 ret
567         }
568
569         /// Constructs a ChannelTypeFeatures with only static_remotekey set
570         pub(crate) fn only_static_remote_key() -> Self {
571                 let mut ret = Self::empty();
572                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
573                 ret
574         }
575 }
576
577 impl ToBase32 for InvoiceFeatures {
578         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
579                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
580                 // minus one before dividing
581                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
582                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
583                 for (byte_idx, byte) in self.flags.iter().enumerate() {
584                         let bit_pos_from_left_0_indexed = byte_idx * 8;
585                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
586                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
587                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
588                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
589                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
590                         if new_u5_idx > 0 {
591                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
592                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
593                         }
594                         if new_u5_idx > 1 {
595                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
596                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
597                         }
598                 }
599                 // Trim the highest feature bits.
600                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
601                         res_u5s.remove(0);
602                 }
603                 writer.write(&res_u5s)
604         }
605 }
606
607 impl Base32Len for InvoiceFeatures {
608         fn base32_len(&self) -> usize {
609                 self.to_base32().len()
610         }
611 }
612
613 impl FromBase32 for InvoiceFeatures {
614         type Err = bech32::Error;
615
616         fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
617                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
618                 // minus one before dividing
619                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
620                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
621                 for (u5_idx, chunk) in field_data.iter().enumerate() {
622                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
623                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
624                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
625                         let chunk_u16 = chunk.to_u8() as u16;
626                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
627                         if new_byte_idx != length_bytes - 1 {
628                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
629                         }
630                 }
631                 // Trim the highest feature bits.
632                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
633                         res_bytes.pop();
634                 }
635                 Ok(InvoiceFeatures::from_le_bytes(res_bytes))
636         }
637 }
638
639 impl<T: sealed::Context> Features<T> {
640         /// Create a blank Features with no features set
641         pub fn empty() -> Self {
642                 Features {
643                         flags: Vec::new(),
644                         mark: PhantomData,
645                 }
646         }
647
648         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
649         /// included in the result.
650         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
651                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
652                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
653                 let mut flags = Vec::new();
654                 for (i, byte) in self.flags.iter().enumerate() {
655                         if i < from_byte_count && i < to_byte_count {
656                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
657                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
658                                 flags.push(byte & from_known_features & to_known_features);
659                         }
660                 }
661                 Features::<C> { flags, mark: PhantomData, }
662         }
663
664         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
665         /// most on-the-wire encodings.
666         ///
667         /// This is not exported to bindings users as we don't support export across multiple T
668         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
669                 Features {
670                         flags,
671                         mark: PhantomData,
672                 }
673         }
674
675         #[cfg(test)]
676         /// Gets the underlying flags set, in LE.
677         pub fn le_flags(&self) -> &Vec<u8> {
678                 &self.flags
679         }
680
681         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
682                 for f in self.flags.iter().rev() { // Swap back to big-endian
683                         f.write(w)?;
684                 }
685                 Ok(())
686         }
687
688         fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
689                 flags.reverse(); // Swap to little-endian
690                 Self {
691                         flags,
692                         mark: PhantomData,
693                 }
694         }
695
696         pub(crate) fn supports_any_optional_bits(&self) -> bool {
697                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
698         }
699
700         /// Returns true if this `Features` object contains required features unknown by `other`.
701         pub fn requires_unknown_bits_from(&self, other: &Features<T>) -> bool {
702                 // Bitwise AND-ing with all even bits set except for known features will select required
703                 // unknown features.
704                 self.flags.iter().enumerate().any(|(i, &byte)| {
705                         const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
706                         const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
707                         let unknown_features = if i < other.flags.len() {
708                                 // Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
709                                 !(other.flags[i]
710                                         | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
711                                         | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
712                         } else {
713                                 0b11_11_11_11
714                         };
715                         (byte & (REQUIRED_FEATURES & unknown_features)) != 0
716                 })
717         }
718
719         /// Returns true if this `Features` object contains unknown feature flags which are set as
720         /// "required".
721         pub fn requires_unknown_bits(&self) -> bool {
722                 // Bitwise AND-ing with all even bits set except for known features will select required
723                 // unknown features.
724                 let byte_count = T::KNOWN_FEATURE_MASK.len();
725                 self.flags.iter().enumerate().any(|(i, &byte)| {
726                         let required_features = 0b01_01_01_01;
727                         let unknown_features = if i < byte_count {
728                                 !T::KNOWN_FEATURE_MASK[i]
729                         } else {
730                                 0b11_11_11_11
731                         };
732                         (byte & (required_features & unknown_features)) != 0
733                 })
734         }
735
736         pub(crate) fn supports_unknown_bits(&self) -> bool {
737                 // Bitwise AND-ing with all even and odd bits set except for known features will select
738                 // both required and optional unknown features.
739                 let byte_count = T::KNOWN_FEATURE_MASK.len();
740                 self.flags.iter().enumerate().any(|(i, &byte)| {
741                         let unknown_features = if i < byte_count {
742                                 !T::KNOWN_FEATURE_MASK[i]
743                         } else {
744                                 0b11_11_11_11
745                         };
746                         (byte & unknown_features) != 0
747                 })
748         }
749
750         // Returns true if the features within `self` are a subset of the features within `other`.
751         pub(crate) fn is_subset(&self, other: &Self) -> bool {
752                 for (idx, byte) in self.flags.iter().enumerate() {
753                         if let Some(other_byte) = other.flags.get(idx) {
754                                 if byte & other_byte != *byte {
755                                         // `self` has bits set that `other` doesn't.
756                                         return false;
757                                 }
758                         } else {
759                                 if *byte > 0 {
760                                         // `self` has a non-zero byte that `other` doesn't.
761                                         return false;
762                                 }
763                         }
764                 }
765                 true
766         }
767
768         /// Sets a required custom feature bit. Errors if `bit` is outside the custom range as defined
769         /// by [bLIP 2] or if it is a known `T` feature.
770         ///
771         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
772         /// be set instead (i.e., `bit - 1`).
773         ///
774         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
775         pub fn set_required_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
776                 self.set_custom_bit(bit - (bit % 2))
777         }
778
779         /// Sets an optional custom feature bit. Errors if `bit` is outside the custom range as defined
780         /// by [bLIP 2] or if it is a known `T` feature.
781         ///
782         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
783         /// set instead (i.e., `bit + 1`).
784         ///
785         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
786         pub fn set_optional_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
787                 self.set_custom_bit(bit + (1 - (bit % 2)))
788         }
789
790         fn set_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
791                 if bit < 256 {
792                         return Err(());
793                 }
794
795                 let byte_offset = bit / 8;
796                 let mask = 1 << (bit - 8 * byte_offset);
797                 if byte_offset < T::KNOWN_FEATURE_MASK.len() {
798                         if (T::KNOWN_FEATURE_MASK[byte_offset] & mask) != 0 {
799                                 return Err(());
800                         }
801                 }
802
803                 if self.flags.len() <= byte_offset {
804                         self.flags.resize(byte_offset + 1, 0u8);
805                 }
806
807                 self.flags[byte_offset] |= mask;
808
809                 Ok(())
810         }
811 }
812
813 impl<T: sealed::UpfrontShutdownScript> Features<T> {
814         #[cfg(test)]
815         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
816                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
817                 self
818         }
819 }
820
821 impl<T: sealed::ShutdownAnySegwit> Features<T> {
822         #[cfg(test)]
823         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
824                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
825                 self
826         }
827 }
828
829 impl<T: sealed::Wumbo> Features<T> {
830         #[cfg(test)]
831         pub(crate) fn clear_wumbo(mut self) -> Self {
832                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
833                 self
834         }
835 }
836
837 impl<T: sealed::SCIDPrivacy> Features<T> {
838         pub(crate) fn clear_scid_privacy(&mut self) {
839                 <T as sealed::SCIDPrivacy>::clear_bits(&mut self.flags);
840         }
841 }
842
843 impl<T: sealed::AnchorsZeroFeeHtlcTx> Features<T> {
844         pub(crate) fn clear_anchors_zero_fee_htlc_tx(&mut self) {
845                 <T as sealed::AnchorsZeroFeeHtlcTx>::clear_bits(&mut self.flags);
846         }
847 }
848
849 #[cfg(test)]
850 impl<T: sealed::UnknownFeature> Features<T> {
851         pub(crate) fn unknown() -> Self {
852                 let mut features = Self::empty();
853                 features.set_unknown_feature_required();
854                 features
855         }
856 }
857
858 macro_rules! impl_feature_len_prefixed_write {
859         ($features: ident) => {
860                 impl Writeable for $features {
861                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
862                                 (self.flags.len() as u16).write(w)?;
863                                 self.write_be(w)
864                         }
865                 }
866                 impl Readable for $features {
867                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
868                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
869                         }
870                 }
871         }
872 }
873 impl_feature_len_prefixed_write!(InitFeatures);
874 impl_feature_len_prefixed_write!(ChannelFeatures);
875 impl_feature_len_prefixed_write!(NodeFeatures);
876 impl_feature_len_prefixed_write!(InvoiceFeatures);
877 impl_feature_len_prefixed_write!(Bolt12InvoiceFeatures);
878 impl_feature_len_prefixed_write!(BlindedHopFeatures);
879
880 // Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
881 macro_rules! impl_feature_tlv_write {
882         ($features: ident) => {
883                 impl Writeable for $features {
884                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
885                                 WithoutLength(self).write(w)
886                         }
887                 }
888                 impl Readable for $features {
889                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
890                                 Ok(WithoutLength::<Self>::read(r)?.0)
891                         }
892                 }
893         }
894 }
895
896 impl_feature_tlv_write!(ChannelTypeFeatures);
897
898 // Some features may appear both in a TLV record and as part of a TLV subtype sequence. The latter
899 // requires a length but the former does not.
900
901 impl<T: sealed::Context> Writeable for WithoutLength<&Features<T>> {
902         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
903                 self.0.write_be(w)
904         }
905 }
906
907 impl<T: sealed::Context> Readable for WithoutLength<Features<T>> {
908         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
909                 let v = io_extras::read_to_end(r)?;
910                 Ok(WithoutLength(Features::<T>::from_be_bytes(v)))
911         }
912 }
913
914 #[cfg(test)]
915 mod tests {
916         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures, OfferFeatures, sealed};
917         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
918         use crate::util::ser::{Readable, WithoutLength, Writeable};
919
920         #[test]
921         fn sanity_test_unknown_bits() {
922                 let features = ChannelFeatures::empty();
923                 assert!(!features.requires_unknown_bits());
924                 assert!(!features.supports_unknown_bits());
925
926                 let mut features = ChannelFeatures::empty();
927                 features.set_unknown_feature_required();
928                 assert!(features.requires_unknown_bits());
929                 assert!(features.supports_unknown_bits());
930
931                 let mut features = ChannelFeatures::empty();
932                 features.set_unknown_feature_optional();
933                 assert!(!features.requires_unknown_bits());
934                 assert!(features.supports_unknown_bits());
935         }
936
937         #[test]
938         fn requires_unknown_bits_from() {
939                 let mut features1 = InitFeatures::empty();
940                 let mut features2 = InitFeatures::empty();
941                 assert!(!features1.requires_unknown_bits_from(&features2));
942                 assert!(!features2.requires_unknown_bits_from(&features1));
943
944                 features1.set_data_loss_protect_required();
945                 assert!(features1.requires_unknown_bits_from(&features2));
946                 assert!(!features2.requires_unknown_bits_from(&features1));
947
948                 features2.set_data_loss_protect_optional();
949                 assert!(!features1.requires_unknown_bits_from(&features2));
950                 assert!(!features2.requires_unknown_bits_from(&features1));
951
952                 features2.set_gossip_queries_required();
953                 assert!(!features1.requires_unknown_bits_from(&features2));
954                 assert!(features2.requires_unknown_bits_from(&features1));
955
956                 features1.set_gossip_queries_optional();
957                 assert!(!features1.requires_unknown_bits_from(&features2));
958                 assert!(!features2.requires_unknown_bits_from(&features1));
959
960                 features1.set_variable_length_onion_required();
961                 assert!(features1.requires_unknown_bits_from(&features2));
962                 assert!(!features2.requires_unknown_bits_from(&features1));
963
964                 features2.set_variable_length_onion_optional();
965                 assert!(!features1.requires_unknown_bits_from(&features2));
966                 assert!(!features2.requires_unknown_bits_from(&features1));
967
968                 features1.set_basic_mpp_required();
969                 features2.set_wumbo_required();
970                 assert!(features1.requires_unknown_bits_from(&features2));
971                 assert!(features2.requires_unknown_bits_from(&features1));
972         }
973
974         #[test]
975         fn convert_to_context_with_relevant_flags() {
976                 let mut init_features = InitFeatures::empty();
977                 // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
978                 // converted as it's only relevant in an init context).
979                 init_features.set_initial_routing_sync_required();
980                 init_features.set_data_loss_protect_required();
981                 init_features.set_variable_length_onion_required();
982                 init_features.set_static_remote_key_required();
983                 init_features.set_payment_secret_required();
984                 init_features.set_basic_mpp_optional();
985                 init_features.set_wumbo_optional();
986                 init_features.set_anchors_zero_fee_htlc_tx_optional();
987                 init_features.set_shutdown_any_segwit_optional();
988                 init_features.set_onion_messages_optional();
989                 init_features.set_channel_type_optional();
990                 init_features.set_scid_privacy_optional();
991                 init_features.set_zero_conf_optional();
992
993                 assert!(init_features.initial_routing_sync());
994                 assert!(!init_features.supports_upfront_shutdown_script());
995                 assert!(!init_features.supports_gossip_queries());
996
997                 let node_features: NodeFeatures = init_features.to_context();
998                 {
999                         // Check that the flags are as expected:
1000                         // - option_data_loss_protect (req)
1001                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
1002                         // - basic_mpp | wumbo | anchors_zero_fee_htlc_tx
1003                         // - opt_shutdown_anysegwit
1004                         // - onion_messages
1005                         // - option_channel_type | option_scid_alias
1006                         // - option_zeroconf
1007                         assert_eq!(node_features.flags.len(), 7);
1008                         assert_eq!(node_features.flags[0], 0b00000001);
1009                         assert_eq!(node_features.flags[1], 0b01010001);
1010                         assert_eq!(node_features.flags[2], 0b10001010);
1011                         assert_eq!(node_features.flags[3], 0b00001000);
1012                         assert_eq!(node_features.flags[4], 0b10000000);
1013                         assert_eq!(node_features.flags[5], 0b10100000);
1014                         assert_eq!(node_features.flags[6], 0b00001000);
1015                 }
1016
1017                 // Check that cleared flags are kept blank when converting back:
1018                 // - initial_routing_sync was not applicable to NodeContext
1019                 // - upfront_shutdown_script was cleared before converting
1020                 // - gossip_queries was cleared before converting
1021                 let features: InitFeatures = node_features.to_context_internal();
1022                 assert!(!features.initial_routing_sync());
1023                 assert!(!features.supports_upfront_shutdown_script());
1024                 assert!(!init_features.supports_gossip_queries());
1025         }
1026
1027         #[test]
1028         fn convert_to_context_with_unknown_flags() {
1029                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1030                 assert!(<sealed::ChannelContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
1031                         <sealed::InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
1032                 let mut channel_features = ChannelFeatures::empty();
1033                 channel_features.set_unknown_feature_optional();
1034                 assert!(channel_features.supports_unknown_bits());
1035                 let invoice_features: InvoiceFeatures = channel_features.to_context_internal();
1036                 assert!(!invoice_features.supports_unknown_bits());
1037         }
1038
1039         #[test]
1040         fn set_feature_bits() {
1041                 let mut features = InvoiceFeatures::empty();
1042                 features.set_basic_mpp_optional();
1043                 features.set_payment_secret_required();
1044                 assert!(features.supports_basic_mpp());
1045                 assert!(!features.requires_basic_mpp());
1046                 assert!(features.requires_payment_secret());
1047                 assert!(features.supports_payment_secret());
1048         }
1049
1050         #[test]
1051         fn set_custom_bits() {
1052                 let mut features = InvoiceFeatures::empty();
1053                 features.set_variable_length_onion_optional();
1054                 assert_eq!(features.flags[1], 0b00000010);
1055
1056                 assert!(features.set_optional_custom_bit(255).is_err());
1057                 assert!(features.set_required_custom_bit(256).is_ok());
1058                 assert!(features.set_required_custom_bit(258).is_ok());
1059                 assert_eq!(features.flags[31], 0b00000000);
1060                 assert_eq!(features.flags[32], 0b00000101);
1061
1062                 let known_bit = <sealed::InvoiceContext as sealed::PaymentSecret>::EVEN_BIT;
1063                 let byte_offset = <sealed::InvoiceContext as sealed::PaymentSecret>::BYTE_OFFSET;
1064                 assert_eq!(byte_offset, 1);
1065                 assert_eq!(features.flags[byte_offset], 0b00000010);
1066                 assert!(features.set_required_custom_bit(known_bit).is_err());
1067                 assert_eq!(features.flags[byte_offset], 0b00000010);
1068
1069                 let mut features = InvoiceFeatures::empty();
1070                 assert!(features.set_optional_custom_bit(256).is_ok());
1071                 assert!(features.set_optional_custom_bit(259).is_ok());
1072                 assert_eq!(features.flags[32], 0b00001010);
1073
1074                 let mut features = InvoiceFeatures::empty();
1075                 assert!(features.set_required_custom_bit(257).is_ok());
1076                 assert!(features.set_required_custom_bit(258).is_ok());
1077                 assert_eq!(features.flags[32], 0b00000101);
1078         }
1079
1080         #[test]
1081         fn encodes_features_without_length() {
1082                 let features = OfferFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1083                 assert_eq!(features.flags.len(), 8);
1084
1085                 let mut serialized_features = Vec::new();
1086                 WithoutLength(&features).write(&mut serialized_features).unwrap();
1087                 assert_eq!(serialized_features.len(), 8);
1088
1089                 let deserialized_features =
1090                         WithoutLength::<OfferFeatures>::read(&mut &serialized_features[..]).unwrap().0;
1091                 assert_eq!(features, deserialized_features);
1092         }
1093
1094         #[test]
1095         fn invoice_features_encoding() {
1096                 let features_as_u5s = vec![
1097                         u5::try_from_u8(6).unwrap(),
1098                         u5::try_from_u8(10).unwrap(),
1099                         u5::try_from_u8(25).unwrap(),
1100                         u5::try_from_u8(1).unwrap(),
1101                         u5::try_from_u8(10).unwrap(),
1102                         u5::try_from_u8(0).unwrap(),
1103                         u5::try_from_u8(20).unwrap(),
1104                         u5::try_from_u8(2).unwrap(),
1105                         u5::try_from_u8(0).unwrap(),
1106                         u5::try_from_u8(6).unwrap(),
1107                         u5::try_from_u8(0).unwrap(),
1108                         u5::try_from_u8(16).unwrap(),
1109                         u5::try_from_u8(1).unwrap(),
1110                 ];
1111                 let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1112
1113                 // Test length calculation.
1114                 assert_eq!(features.base32_len(), 13);
1115
1116                 // Test serialization.
1117                 let features_serialized = features.to_base32();
1118                 assert_eq!(features_as_u5s, features_serialized);
1119
1120                 // Test deserialization.
1121                 let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1122                 assert_eq!(features, features_deserialized);
1123         }
1124
1125         #[test]
1126         fn test_channel_type_mapping() {
1127                 // If we map an InvoiceFeatures with StaticRemoteKey optional, it should map into a
1128                 // required-StaticRemoteKey ChannelTypeFeatures.
1129                 let mut init_features = InitFeatures::empty();
1130                 init_features.set_static_remote_key_optional();
1131                 let converted_features = ChannelTypeFeatures::from_init(&init_features);
1132                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1133                 assert!(!converted_features.supports_any_optional_bits());
1134                 assert!(converted_features.requires_static_remote_key());
1135         }
1136 }