_ Git - rust-lightning/blob - 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 //! - `ShutdownAnySegwit` - requires/supports that future segwit versions are allowed in `shutdown`
  43 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  44 //! - `ChannelType` - node supports the channel_type field in open/accept
  45 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  46 //! - `SCIDPrivacy` - supply channel aliases for routing
  47 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  48 //! - `Keysend` - send funds to a node without an invoice
  49 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
  50 //!
  51 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
  52 //! [messages]: crate::ln::msgs
  53
  54 use {io, io_extras};
  55 use prelude::*;
  56 use core::{cmp, fmt};
  57 use core::hash::{Hash, Hasher};
  58 use core::marker::PhantomData;
  59
  60 use bitcoin::bech32;
  61 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
  62 use ln::msgs::DecodeError;
  63 use util::ser::{Readable, Writeable, Writer};
  64
  65 mod sealed {
  66         use prelude::*;
  67         use ln::features::Features;
  68
  69         /// The context in which [`Features`] are applicable. Defines which features are required and
  70         /// which are optional for the context.
  71         pub trait Context {
  72                 /// Features that are known to the implementation, where a required feature is indicated by
  73                 /// its even bit and an optional feature is indicated by its odd bit.
  74                 const KNOWN_FEATURE_FLAGS: &'static [u8];
  75
  76                 /// Bitmask for selecting features that are known to the implementation, regardless of
  77                 /// whether each feature is required or optional.
  78                 const KNOWN_FEATURE_MASK: &'static [u8];
  79         }
  80
  81         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
  82         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
  83         /// feature identifiers.
  84         macro_rules! define_context {
  85                 ($context: ident {
  86                         required_features: [$( $( $required_feature: ident )|*, )*],
  87                         optional_features: [$( $( $optional_feature: ident )|*, )*],
  88                 }) => {
  89                         #[derive(Eq, PartialEq)]
  90                         pub struct $context {}
  91
  92                         impl Context for $context {
  93                                 const KNOWN_FEATURE_FLAGS: &'static [u8] = &[
  94                                         // For each byte, use bitwise-OR to compute the applicable flags for known
  95                                         // required features `r_i` and optional features `o_j` for all `i` and `j` such
  96                                         // that the following slice is formed:
  97                                         //
  98                                         // [
  99                                         //  `r_0` | `r_1` | ... | `o_0` | `o_1` | ...,
 100                                         //  ...,
 101                                         // ]
 102                                         $(
 103                                                 0b00_00_00_00 $(|
 104                                                         <Self as $required_feature>::REQUIRED_MASK)*
 105                                                 $(|
 106                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
 107                                         )*
 108                                 ];
 109
 110                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
 111                                         // Similar as above, but set both flags for each feature regardless of whether
 112                                         // the feature is required or optional.
 113                                         $(
 114                                                 0b00_00_00_00 $(|
 115                                                         <Self as $required_feature>::REQUIRED_MASK |
 116                                                         <Self as $required_feature>::OPTIONAL_MASK)*
 117                                                 $(|
 118                                                         <Self as $optional_feature>::REQUIRED_MASK |
 119                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
 120                                         )*
 121                                 ];
 122                         }
 123
 124                         impl alloc::fmt::Display for Features<$context> {
 125                                 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
 126                                         $(
 127                                                 $(
 128                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($required_feature),
 129                                                                 if <$context as $required_feature>::requires_feature(&self.flags) { "required" }
 130                                                                 else if <$context as $required_feature>::supports_feature(&self.flags) { "supported" }
 131                                                                 else { "not supported" }))?;
 132                                                 )*
 133                                                 $(
 134                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($optional_feature),
 135                                                                 if <$context as $optional_feature>::requires_feature(&self.flags) { "required" }
 136                                                                 else if <$context as $optional_feature>::supports_feature(&self.flags) { "supported" }
 137                                                                 else { "not supported" }))?;
 138                                                 )*
 139                                         )*
 140                                         fmt.write_fmt(format_args!("unknown flags: {}",
 141                                                 if self.requires_unknown_bits() { "required" }
 142                                                 else if self.supports_unknown_bits() { "supported" } else { "none" }))
 143                                 }
 144                         }
 145                 };
 146         }
 147
 148         define_context!(InitContext {
 149                 required_features: [
 150                         // Byte 0
 151                         ,
 152                         // Byte 1
 153                         VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 154                         // Byte 2
 155                         ,
 156                         // Byte 3
 157                         ,
 158                         // Byte 4
 159                         ,
 160                         // Byte 5
 161                         ,
 162                         // Byte 6
 163                         ,
 164                 ],
 165                 optional_features: [
 166                         // Note that if new "non-channel-related" flags are added here they should be
 167                         // explicitly cleared in InitFeatures::known_channel_features.
 168                         // Byte 0
 169                         DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
 170                         // Byte 1
 171                         ,
 172                         // Byte 2
 173                         BasicMPP | Wumbo,
 174                         // Byte 3
 175                         ShutdownAnySegwit,
 176                         // Byte 4
 177                         ,
 178                         // Byte 5
 179                         ChannelType | SCIDPrivacy,
 180                         // Byte 6
 181                         ZeroConf,
 182                 ],
 183         });
 184         define_context!(NodeContext {
 185                 required_features: [
 186                         // Byte 0
 187                         ,
 188                         // Byte 1
 189                         VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 190                         // Byte 2
 191                         ,
 192                         // Byte 3
 193                         ,
 194                         // Byte 4
 195                         ,
 196                         // Byte 5
 197                         ,
 198                         // Byte 6
 199                         ,
 200                 ],
 201                 optional_features: [
 202                         // Byte 0
 203                         DataLossProtect | UpfrontShutdownScript | GossipQueries,
 204                         // Byte 1
 205                         ,
 206                         // Byte 2
 207                         BasicMPP | Wumbo,
 208                         // Byte 3
 209                         ShutdownAnySegwit,
 210                         // Byte 4
 211                         ,
 212                         // Byte 5
 213                         ChannelType | SCIDPrivacy,
 214                         // Byte 6
 215                         ZeroConf | Keysend,
 216                 ],
 217         });
 218         define_context!(ChannelContext {
 219                 required_features: [],
 220                 optional_features: [],
 221         });
 222         define_context!(InvoiceContext {
 223                 required_features: [
 224                         // Byte 0
 225                         ,
 226                         // Byte 1
 227                         VariableLengthOnion | PaymentSecret,
 228                         // Byte 2
 229                         ,
 230                 ],
 231                 optional_features: [
 232                         // Byte 0
 233                         ,
 234                         // Byte 1
 235                         ,
 236                         // Byte 2
 237                         BasicMPP,
 238                 ],
 239         });
 240         // This isn't a "real" feature context, and is only used in the channel_type field in an
 241         // `OpenChannel` message.
 242         define_context!(ChannelTypeContext {
 243                 required_features: [
 244                         // Byte 0
 245                         ,
 246                         // Byte 1
 247                         StaticRemoteKey,
 248                         // Byte 2
 249                         ,
 250                         // Byte 3
 251                         ,
 252                         // Byte 4
 253                         ,
 254                         // Byte 5
 255                         SCIDPrivacy,
 256                         // Byte 6
 257                         ZeroConf,
 258                 ],
 259                 optional_features: [
 260                         // Byte 0
 261                         ,
 262                         // Byte 1
 263                         ,
 264                         // Byte 2
 265                         ,
 266                         // Byte 3
 267                         ,
 268                         // Byte 4
 269                         ,
 270                         // Byte 5
 271                         ,
 272                         // Byte 6
 273                         ,
 274                 ],
 275         });
 276
 277         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
 278         /// useful for manipulating feature flags.
 279         macro_rules! define_feature {
 280                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 281                  $required_setter: ident, $supported_getter: ident) => {
 282                         #[doc = $doc]
 283                         ///
 284                         /// See [BOLT #9] for details.
 285                         ///
 286                         /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 287                         pub trait $feature: Context {
 288                                 /// The bit used to signify that the feature is required.
 289                                 const EVEN_BIT: usize = $odd_bit - 1;
 290
 291                                 /// The bit used to signify that the feature is optional.
 292                                 const ODD_BIT: usize = $odd_bit;
 293
 294                                 /// Assertion that [`EVEN_BIT`] is actually even.
 295                                 ///
 296                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
 297                                 const ASSERT_EVEN_BIT_PARITY: usize;
 298
 299                                 /// Assertion that [`ODD_BIT`] is actually odd.
 300                                 ///
 301                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
 302                                 const ASSERT_ODD_BIT_PARITY: usize;
 303
 304                                 /// The byte where the feature is set.
 305                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
 306
 307                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
 308                                 ///
 309                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 310                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
 311
 312                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
 313                                 ///
 314                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 315                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
 316
 317                                 /// Returns whether the feature is required by the given flags.
 318                                 #[inline]
 319                                 fn requires_feature(flags: &Vec<u8>) -> bool {
 320                                         flags.len() > Self::BYTE_OFFSET &&
 321                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
 322                                 }
 323
 324                                 /// Returns whether the feature is supported by the given flags.
 325                                 #[inline]
 326                                 fn supports_feature(flags: &Vec<u8>) -> bool {
 327                                         flags.len() > Self::BYTE_OFFSET &&
 328                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
 329                                 }
 330
 331                                 /// Sets the feature's required (even) bit in the given flags.
 332                                 #[inline]
 333                                 fn set_required_bit(flags: &mut Vec<u8>) {
 334                                         if flags.len() <= Self::BYTE_OFFSET {
 335                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 336                                         }
 337
 338                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
 339                                 }
 340
 341                                 /// Sets the feature's optional (odd) bit in the given flags.
 342                                 #[inline]
 343                                 fn set_optional_bit(flags: &mut Vec<u8>) {
 344                                         if flags.len() <= Self::BYTE_OFFSET {
 345                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 346                                         }
 347
 348                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
 349                                 }
 350
 351                                 /// Clears the feature's required (even) and optional (odd) bits from the given
 352                                 /// flags.
 353                                 #[inline]
 354                                 fn clear_bits(flags: &mut Vec<u8>) {
 355                                         if flags.len() > Self::BYTE_OFFSET {
 356                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
 357                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 358                                         }
 359
 360                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
 361                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
 362                                         flags.resize(size, 0u8);
 363                                 }
 364                         }
 365
 366                         impl <T: $feature> Features<T> {
 367                                 /// Set this feature as optional.
 368                                 pub fn $optional_setter(&mut self) {
 369                                         <T as $feature>::set_optional_bit(&mut self.flags);
 370                                 }
 371
 372                                 /// Set this feature as required.
 373                                 pub fn $required_setter(&mut self) {
 374                                         <T as $feature>::set_required_bit(&mut self.flags);
 375                                 }
 376
 377                                 /// Checks if this feature is supported.
 378                                 pub fn $supported_getter(&self) -> bool {
 379                                         <T as $feature>::supports_feature(&self.flags)
 380                                 }
 381                         }
 382
 383                         $(
 384                                 impl $feature for $context {
 385                                         // EVEN_BIT % 2 == 0
 386                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
 387
 388                                         // ODD_BIT % 2 == 1
 389                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
 390                                 }
 391                         )*
 392                 };
 393                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 394                  $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
 395                         define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
 396                         impl <T: $feature> Features<T> {
 397                                 /// Checks if this feature is required.
 398                                 pub fn $required_getter(&self) -> bool {
 399                                         <T as $feature>::requires_feature(&self.flags)
 400                                 }
 401                         }
 402                 }
 403         }
 404
 405         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
 406                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
 407                 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
 408         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
 409         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
 410                 set_initial_routing_sync_optional, set_initial_routing_sync_required,
 411                 initial_routing_sync);
 412         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
 413                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
 414                 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
 415                 requires_upfront_shutdown_script);
 416         define_feature!(7, GossipQueries, [InitContext, NodeContext],
 417                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
 418                 supports_gossip_queries, requires_gossip_queries);
 419         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
 420                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
 421                 set_variable_length_onion_required, supports_variable_length_onion,
 422                 requires_variable_length_onion);
 423         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
 424                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
 425                 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
 426         define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
 427                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
 428                 supports_payment_secret, requires_payment_secret);
 429         define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext],
 430                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
 431                 supports_basic_mpp, requires_basic_mpp);
 432         define_feature!(19, Wumbo, [InitContext, NodeContext],
 433                 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
 434                 supports_wumbo, requires_wumbo);
 435         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
 436                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
 437                 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
 438         // We do not yet advertise the onion messages feature bit, but we need to detect when peers
 439         // support it.
 440         define_feature!(39, OnionMessages, [InitContext, NodeContext],
 441                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
 442                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
 443         define_feature!(45, ChannelType, [InitContext, NodeContext],
 444                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
 445                 set_channel_type_required, supports_channel_type, requires_channel_type);
 446         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
 447                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
 448                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
 449         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
 450                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
 451                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
 452         define_feature!(55, Keysend, [NodeContext],
 453                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
 454                 supports_keysend, requires_keysend);
 455
 456         #[cfg(test)]
 457         define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext, InvoiceContext],
 458                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
 459                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
 460 }
 461
 462 /// Tracks the set of features which a node implements, templated by the context in which it
 463 /// appears.
 464 ///
 465 /// (C-not exported) as we map the concrete feature types below directly instead
 466 #[derive(Eq)]
 467 pub struct Features<T: sealed::Context> {
 468         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
 469         flags: Vec<u8>,
 470         mark: PhantomData<T>,
 471 }
 472
 473 impl <T: sealed::Context> Features<T> {
 474         pub(crate) fn or(mut self, o: Self) -> Self {
 475                 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
 476                 self.flags.resize(total_feature_len, 0u8);
 477                 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
 478                         *byte |= *o_byte;
 479                 }
 480                 self
 481         }
 482 }
 483
 484 impl<T: sealed::Context> Clone for Features<T> {
 485         fn clone(&self) -> Self {
 486                 Self {
 487                         flags: self.flags.clone(),
 488                         mark: PhantomData,
 489                 }
 490         }
 491 }
 492 impl<T: sealed::Context> Hash for Features<T> {
 493         fn hash<H: Hasher>(&self, hasher: &mut H) {
 494                 self.flags.hash(hasher);
 495         }
 496 }
 497 impl<T: sealed::Context> PartialEq for Features<T> {
 498         fn eq(&self, o: &Self) -> bool {
 499                 self.flags.eq(&o.flags)
 500         }
 501 }
 502 impl<T: sealed::Context> fmt::Debug for Features<T> {
 503         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 504                 self.flags.fmt(fmt)
 505         }
 506 }
 507
 508 /// Features used within an `init` message.
 509 pub type InitFeatures = Features<sealed::InitContext>;
 510 /// Features used within a `node_announcement` message.
 511 pub type NodeFeatures = Features<sealed::NodeContext>;
 512 /// Features used within a `channel_announcement` message.
 513 pub type ChannelFeatures = Features<sealed::ChannelContext>;
 514 /// Features used within an invoice.
 515 pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
 516
 517 /// Features used within the channel_type field in an OpenChannel message.
 518 ///
 519 /// A channel is always of some known "type", describing the transaction formats used and the exact
 520 /// semantics of our interaction with our peer.
 521 ///
 522 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
 523 /// the counterparty, only required features are allowed here.
 524 ///
 525 /// This is serialized differently from other feature types - it is not prefixed by a length, and
 526 /// thus must only appear inside a TLV where its length is known in advance.
 527 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
 528
 529 impl InitFeatures {
 530         /// Writes all features present up to, and including, 13.
 531         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 532                 let len = cmp::min(2, self.flags.len());
 533                 (len as u16).write(w)?;
 534                 for i in (0..len).rev() {
 535                         if i == 0 {
 536                                 self.flags[i].write(w)?;
 537                         } else {
 538                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
 539                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
 540                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
 541                         }
 542                 }
 543                 Ok(())
 544         }
 545
 546         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
 547         /// are included in the result.
 548         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 549                 self.to_context_internal()
 550         }
 551
 552         /// Returns the set of known init features that are related to channels. At least some of
 553         /// these features are likely required for peers to talk to us.
 554         pub fn known_channel_features() -> InitFeatures {
 555                 Self::known()
 556                         .clear_initial_routing_sync()
 557                         .clear_gossip_queries()
 558         }
 559 }
 560
 561 impl InvoiceFeatures {
 562         /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
 563         /// context `C` are included in the result.
 564         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 565                 self.to_context_internal()
 566         }
 567
 568         /// Getting a route for a keysend payment to a private node requires providing the payee's
 569         /// features (since they were not announced in a node announcement). However, keysend payments
 570         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
 571         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
 572         /// `InvoiceFeatures` for [`find_route`].
 573         ///
 574         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
 575         /// [`find_route`]: crate::routing::router::find_route
 576         pub(crate) fn for_keysend() -> InvoiceFeatures {
 577                 let mut res = InvoiceFeatures::empty();
 578                 res.set_variable_length_onion_optional();
 579                 res
 580         }
 581 }
 582
 583 impl ChannelTypeFeatures {
 584         /// Constructs the implicit channel type based on the common supported types between us and our
 585         /// counterparty
 586         pub(crate) fn from_counterparty_init(counterparty_init: &InitFeatures) -> Self {
 587                 let mut ret = counterparty_init.to_context_internal();
 588                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
 589                 // optional bits and then AND out the optional ones.
 590                 for byte in ret.flags.iter_mut() {
 591                         *byte |= (*byte & 0b10_10_10_10) >> 1;
 592                         *byte &= 0b01_01_01_01;
 593                 }
 594                 ret
 595         }
 596
 597         /// Constructs a ChannelTypeFeatures with only static_remotekey set
 598         pub(crate) fn only_static_remote_key() -> Self {
 599                 let mut ret = Self::empty();
 600                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
 601                 ret
 602         }
 603 }
 604
 605 impl ToBase32 for InvoiceFeatures {
 606         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
 607                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
 608                 // minus one before dividing
 609                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
 610                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
 611                 for (byte_idx, byte) in self.flags.iter().enumerate() {
 612                         let bit_pos_from_left_0_indexed = byte_idx * 8;
 613                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
 614                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
 615                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
 616                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
 617                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
 618                         if new_u5_idx > 0 {
 619                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
 620                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
 621                         }
 622                         if new_u5_idx > 1 {
 623                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
 624                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
 625                         }
 626                 }
 627                 // Trim the highest feature bits.
 628                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
 629                         res_u5s.remove(0);
 630                 }
 631                 writer.write(&res_u5s)
 632         }
 633 }
 634
 635 impl Base32Len for InvoiceFeatures {
 636         fn base32_len(&self) -> usize {
 637                 self.to_base32().len()
 638         }
 639 }
 640
 641 impl FromBase32 for InvoiceFeatures {
 642         type Err = bech32::Error;
 643
 644         fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
 645                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
 646                 // minus one before dividing
 647                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
 648                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
 649                 for (u5_idx, chunk) in field_data.iter().enumerate() {
 650                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
 651                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
 652                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
 653                         let chunk_u16 = chunk.to_u8() as u16;
 654                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
 655                         if new_byte_idx != length_bytes - 1 {
 656                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
 657                         }
 658                 }
 659                 // Trim the highest feature bits.
 660                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
 661                         res_bytes.pop();
 662                 }
 663                 Ok(InvoiceFeatures::from_le_bytes(res_bytes))
 664         }
 665 }
 666
 667 impl<T: sealed::Context> Features<T> {
 668         /// Create a blank Features with no features set
 669         pub fn empty() -> Self {
 670                 Features {
 671                         flags: Vec::new(),
 672                         mark: PhantomData,
 673                 }
 674         }
 675
 676         /// Creates a Features with the bits set which are known by the implementation
 677         pub fn known() -> Self {
 678                 Self {
 679                         flags: T::KNOWN_FEATURE_FLAGS.to_vec(),
 680                         mark: PhantomData,
 681                 }
 682         }
 683
 684         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
 685         /// included in the result.
 686         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
 687                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
 688                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
 689                 let mut flags = Vec::new();
 690                 for (i, byte) in self.flags.iter().enumerate() {
 691                         if i < from_byte_count && i < to_byte_count {
 692                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
 693                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
 694                                 flags.push(byte & from_known_features & to_known_features);
 695                         }
 696                 }
 697                 Features::<C> { flags, mark: PhantomData, }
 698         }
 699
 700         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
 701         /// most on-the-wire encodings.
 702         /// (C-not exported) as we don't support export across multiple T
 703         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 704                 Features {
 705                         flags,
 706                         mark: PhantomData,
 707                 }
 708         }
 709
 710         #[cfg(test)]
 711         /// Gets the underlying flags set, in LE.
 712         pub fn le_flags(&self) -> &Vec<u8> {
 713                 &self.flags
 714         }
 715
 716         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 717                 for f in self.flags.iter().rev() { // Swap back to big-endian
 718                         f.write(w)?;
 719                 }
 720                 Ok(())
 721         }
 722
 723         fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
 724                 flags.reverse(); // Swap to little-endian
 725                 Self {
 726                         flags,
 727                         mark: PhantomData,
 728                 }
 729         }
 730
 731         pub(crate) fn supports_any_optional_bits(&self) -> bool {
 732                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
 733         }
 734
 735         /// Returns true if this `Features` object contains unknown feature flags which are set as
 736         /// "required".
 737         pub fn requires_unknown_bits(&self) -> bool {
 738                 // Bitwise AND-ing with all even bits set except for known features will select required
 739                 // unknown features.
 740                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 741                 self.flags.iter().enumerate().any(|(i, &byte)| {
 742                         let required_features = 0b01_01_01_01;
 743                         let unknown_features = if i < byte_count {
 744                                 !T::KNOWN_FEATURE_MASK[i]
 745                         } else {
 746                                 0b11_11_11_11
 747                         };
 748                         (byte & (required_features & unknown_features)) != 0
 749                 })
 750         }
 751
 752         pub(crate) fn supports_unknown_bits(&self) -> bool {
 753                 // Bitwise AND-ing with all even and odd bits set except for known features will select
 754                 // both required and optional unknown features.
 755                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 756                 self.flags.iter().enumerate().any(|(i, &byte)| {
 757                         let unknown_features = if i < byte_count {
 758                                 !T::KNOWN_FEATURE_MASK[i]
 759                         } else {
 760                                 0b11_11_11_11
 761                         };
 762                         (byte & unknown_features) != 0
 763                 })
 764         }
 765 }
 766
 767 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 768         #[cfg(test)]
 769         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
 770                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
 771                 self
 772         }
 773 }
 774
 775
 776 impl<T: sealed::GossipQueries> Features<T> {
 777         pub(crate) fn clear_gossip_queries(mut self) -> Self {
 778                 <T as sealed::GossipQueries>::clear_bits(&mut self.flags);
 779                 self
 780         }
 781 }
 782
 783 impl<T: sealed::InitialRoutingSync> Features<T> {
 784         // Note that initial_routing_sync is ignored if gossip_queries is set.
 785         pub(crate) fn clear_initial_routing_sync(mut self) -> Self {
 786                 <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags);
 787                 self
 788         }
 789 }
 790
 791 impl<T: sealed::ShutdownAnySegwit> Features<T> {
 792         #[cfg(test)]
 793         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
 794                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
 795                 self
 796         }
 797 }
 798
 799 impl<T: sealed::Wumbo> Features<T> {
 800         #[cfg(test)]
 801         pub(crate) fn clear_wumbo(mut self) -> Self {
 802                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
 803                 self
 804         }
 805 }
 806
 807 macro_rules! impl_feature_len_prefixed_write {
 808         ($features: ident) => {
 809                 impl Writeable for $features {
 810                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 811                                 (self.flags.len() as u16).write(w)?;
 812                                 self.write_be(w)
 813                         }
 814                 }
 815                 impl Readable for $features {
 816                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 817                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
 818                         }
 819                 }
 820         }
 821 }
 822 impl_feature_len_prefixed_write!(InitFeatures);
 823 impl_feature_len_prefixed_write!(ChannelFeatures);
 824 impl_feature_len_prefixed_write!(NodeFeatures);
 825 impl_feature_len_prefixed_write!(InvoiceFeatures);
 826
 827 // Because ChannelTypeFeatures only appears inside of TLVs, it doesn't have a length prefix when
 828 // serialized. Thus, we can't use `impl_feature_len_prefixed_write`, above, and have to write our
 829 // own serialization.
 830 impl Writeable for ChannelTypeFeatures {
 831         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 832                 self.write_be(w)
 833         }
 834 }
 835 impl Readable for ChannelTypeFeatures {
 836         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 837                 let v = io_extras::read_to_end(r)?;
 838                 Ok(Self::from_be_bytes(v))
 839         }
 840 }
 841
 842 #[cfg(test)]
 843 mod tests {
 844         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
 845         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
 846
 847         #[test]
 848         fn sanity_test_known_features() {
 849                 assert!(!ChannelFeatures::known().requires_unknown_bits());
 850                 assert!(!ChannelFeatures::known().supports_unknown_bits());
 851                 assert!(!InitFeatures::known().requires_unknown_bits());
 852                 assert!(!InitFeatures::known().supports_unknown_bits());
 853                 assert!(!NodeFeatures::known().requires_unknown_bits());
 854                 assert!(!NodeFeatures::known().supports_unknown_bits());
 855
 856                 assert!(InitFeatures::known().supports_upfront_shutdown_script());
 857                 assert!(NodeFeatures::known().supports_upfront_shutdown_script());
 858                 assert!(!InitFeatures::known().requires_upfront_shutdown_script());
 859                 assert!(!NodeFeatures::known().requires_upfront_shutdown_script());
 860
 861                 assert!(InitFeatures::known().supports_gossip_queries());
 862                 assert!(NodeFeatures::known().supports_gossip_queries());
 863                 assert!(!InitFeatures::known().requires_gossip_queries());
 864                 assert!(!NodeFeatures::known().requires_gossip_queries());
 865
 866                 assert!(InitFeatures::known().supports_data_loss_protect());
 867                 assert!(NodeFeatures::known().supports_data_loss_protect());
 868                 assert!(!InitFeatures::known().requires_data_loss_protect());
 869                 assert!(!NodeFeatures::known().requires_data_loss_protect());
 870
 871                 assert!(InitFeatures::known().supports_variable_length_onion());
 872                 assert!(NodeFeatures::known().supports_variable_length_onion());
 873                 assert!(InvoiceFeatures::known().supports_variable_length_onion());
 874                 assert!(InitFeatures::known().requires_variable_length_onion());
 875                 assert!(NodeFeatures::known().requires_variable_length_onion());
 876                 assert!(InvoiceFeatures::known().requires_variable_length_onion());
 877
 878                 assert!(InitFeatures::known().supports_static_remote_key());
 879                 assert!(NodeFeatures::known().supports_static_remote_key());
 880                 assert!(InitFeatures::known().requires_static_remote_key());
 881                 assert!(NodeFeatures::known().requires_static_remote_key());
 882
 883                 assert!(InitFeatures::known().supports_payment_secret());
 884                 assert!(NodeFeatures::known().supports_payment_secret());
 885                 assert!(InvoiceFeatures::known().supports_payment_secret());
 886                 assert!(InitFeatures::known().requires_payment_secret());
 887                 assert!(NodeFeatures::known().requires_payment_secret());
 888                 assert!(InvoiceFeatures::known().requires_payment_secret());
 889
 890                 assert!(InitFeatures::known().supports_basic_mpp());
 891                 assert!(NodeFeatures::known().supports_basic_mpp());
 892                 assert!(InvoiceFeatures::known().supports_basic_mpp());
 893                 assert!(!InitFeatures::known().requires_basic_mpp());
 894                 assert!(!NodeFeatures::known().requires_basic_mpp());
 895                 assert!(!InvoiceFeatures::known().requires_basic_mpp());
 896
 897                 assert!(InitFeatures::known().supports_channel_type());
 898                 assert!(NodeFeatures::known().supports_channel_type());
 899                 assert!(!InitFeatures::known().requires_channel_type());
 900                 assert!(!NodeFeatures::known().requires_channel_type());
 901
 902                 assert!(InitFeatures::known().supports_shutdown_anysegwit());
 903                 assert!(NodeFeatures::known().supports_shutdown_anysegwit());
 904
 905                 assert!(InitFeatures::known().supports_scid_privacy());
 906                 assert!(NodeFeatures::known().supports_scid_privacy());
 907                 assert!(ChannelTypeFeatures::known().supports_scid_privacy());
 908                 assert!(!InitFeatures::known().requires_scid_privacy());
 909                 assert!(!NodeFeatures::known().requires_scid_privacy());
 910                 assert!(ChannelTypeFeatures::known().requires_scid_privacy());
 911
 912                 assert!(InitFeatures::known().supports_wumbo());
 913                 assert!(NodeFeatures::known().supports_wumbo());
 914                 assert!(!InitFeatures::known().requires_wumbo());
 915                 assert!(!NodeFeatures::known().requires_wumbo());
 916
 917                 assert!(InitFeatures::known().supports_zero_conf());
 918                 assert!(!InitFeatures::known().requires_zero_conf());
 919                 assert!(NodeFeatures::known().supports_zero_conf());
 920                 assert!(!NodeFeatures::known().requires_zero_conf());
 921                 assert!(ChannelTypeFeatures::known().supports_zero_conf());
 922                 assert!(ChannelTypeFeatures::known().requires_zero_conf());
 923
 924                 let mut init_features = InitFeatures::known();
 925                 assert!(init_features.initial_routing_sync());
 926                 init_features = init_features.clear_initial_routing_sync();
 927                 assert!(!init_features.initial_routing_sync());
 928         }
 929
 930         #[test]
 931         fn sanity_test_unknown_bits() {
 932                 let features = ChannelFeatures::empty();
 933                 assert!(!features.requires_unknown_bits());
 934                 assert!(!features.supports_unknown_bits());
 935
 936                 let mut features = ChannelFeatures::empty();
 937                 features.set_unknown_feature_required();
 938                 assert!(features.requires_unknown_bits());
 939                 assert!(features.supports_unknown_bits());
 940
 941                 let mut features = ChannelFeatures::empty();
 942                 features.set_unknown_feature_optional();
 943                 assert!(!features.requires_unknown_bits());
 944                 assert!(features.supports_unknown_bits());
 945         }
 946
 947         #[test]
 948         fn convert_to_context_with_relevant_flags() {
 949                 let init_features = InitFeatures::known().clear_upfront_shutdown_script().clear_gossip_queries();
 950                 assert!(init_features.initial_routing_sync());
 951                 assert!(!init_features.supports_upfront_shutdown_script());
 952                 assert!(!init_features.supports_gossip_queries());
 953
 954                 let node_features: NodeFeatures = init_features.to_context();
 955                 {
 956                         // Check that the flags are as expected:
 957                         // - option_data_loss_protect
 958                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
 959                         // - basic_mpp | wumbo
 960                         // - opt_shutdown_anysegwit
 961                         // -
 962                         // - option_channel_type | option_scid_alias
 963                         // - option_zeroconf
 964                         assert_eq!(node_features.flags.len(), 7);
 965                         assert_eq!(node_features.flags[0], 0b00000010);
 966                         assert_eq!(node_features.flags[1], 0b01010001);
 967                         assert_eq!(node_features.flags[2], 0b00001010);
 968                         assert_eq!(node_features.flags[3], 0b00001000);
 969                         assert_eq!(node_features.flags[4], 0b00000000);
 970                         assert_eq!(node_features.flags[5], 0b10100000);
 971                         assert_eq!(node_features.flags[6], 0b00001000);
 972                 }
 973
 974                 // Check that cleared flags are kept blank when converting back:
 975                 // - initial_routing_sync was not applicable to NodeContext
 976                 // - upfront_shutdown_script was cleared before converting
 977                 // - gossip_queries was cleared before converting
 978                 let features: InitFeatures = node_features.to_context_internal();
 979                 assert!(!features.initial_routing_sync());
 980                 assert!(!features.supports_upfront_shutdown_script());
 981                 assert!(!init_features.supports_gossip_queries());
 982         }
 983
 984         #[test]
 985         fn convert_to_context_with_unknown_flags() {
 986                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
 987                 assert!(InvoiceFeatures::known().flags.len() < NodeFeatures::known().flags.len());
 988                 let mut invoice_features = InvoiceFeatures::known();
 989                 invoice_features.set_unknown_feature_optional();
 990                 assert!(invoice_features.supports_unknown_bits());
 991                 let node_features: NodeFeatures = invoice_features.to_context();
 992                 assert!(!node_features.supports_unknown_bits());
 993         }
 994
 995         #[test]
 996         fn set_feature_bits() {
 997                 let mut features = InvoiceFeatures::empty();
 998                 features.set_basic_mpp_optional();
 999                 features.set_payment_secret_required();
1000                 assert!(features.supports_basic_mpp());
1001                 assert!(!features.requires_basic_mpp());
1002                 assert!(features.requires_payment_secret());
1003                 assert!(features.supports_payment_secret());
1004         }
1005
1006         #[test]
1007         fn invoice_features_encoding() {
1008                 let features_as_u5s = vec![
1009                         u5::try_from_u8(6).unwrap(),
1010                         u5::try_from_u8(10).unwrap(),
1011                         u5::try_from_u8(25).unwrap(),
1012                         u5::try_from_u8(1).unwrap(),
1013                         u5::try_from_u8(10).unwrap(),
1014                         u5::try_from_u8(0).unwrap(),
1015                         u5::try_from_u8(20).unwrap(),
1016                         u5::try_from_u8(2).unwrap(),
1017                         u5::try_from_u8(0).unwrap(),
1018                         u5::try_from_u8(6).unwrap(),
1019                         u5::try_from_u8(0).unwrap(),
1020                         u5::try_from_u8(16).unwrap(),
1021                         u5::try_from_u8(1).unwrap(),
1022                 ];
1023                 let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1024
1025                 // Test length calculation.
1026                 assert_eq!(features.base32_len(), 13);
1027
1028                 // Test serialization.
1029                 let features_serialized = features.to_base32();
1030                 assert_eq!(features_as_u5s, features_serialized);
1031
1032                 // Test deserialization.
1033                 let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1034                 assert_eq!(features, features_deserialized);
1035         }
1036
1037         #[test]
1038         fn test_channel_type_mapping() {
1039                 // If we map an InvoiceFeatures with StaticRemoteKey optional, it should map into a
1040                 // required-StaticRemoteKey ChannelTypeFeatures.
1041                 let mut init_features = InitFeatures::empty();
1042                 init_features.set_static_remote_key_optional();
1043                 let converted_features = ChannelTypeFeatures::from_counterparty_init(&init_features);
1044                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1045                 assert!(!converted_features.supports_any_optional_bits());
1046                 assert!(converted_features.requires_static_remote_key());
1047         }
1048 }