_ 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 //! - `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 //! - `ChannelType` - node supports the channel_type field in open/accept
  47 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  48 //! - `SCIDPrivacy` - supply channel aliases for routing
  49 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  50 //! - `Keysend` - send funds to a node without an invoice
  51 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
  52 //!
  53 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
  54 //! [messages]: crate::ln::msgs
  55
  56 use {io, io_extras};
  57 use prelude::*;
  58 use core::{cmp, fmt};
  59 use core::hash::{Hash, Hasher};
  60 use core::marker::PhantomData;
  61
  62 use bitcoin::bech32;
  63 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
  64 use ln::msgs::DecodeError;
  65 use util::ser::{Readable, Writeable, Writer};
  66
  67 mod sealed {
  68         use prelude::*;
  69         use ln::features::Features;
  70
  71         /// The context in which [`Features`] are applicable. Defines which features are required and
  72         /// which are optional for the context.
  73         pub trait Context {
  74                 /// Features that are known to the implementation, where a required feature is indicated by
  75                 /// its even bit and an optional feature is indicated by its odd bit.
  76                 const KNOWN_FEATURE_FLAGS: &'static [u8];
  77
  78                 /// Bitmask for selecting features that are known to the implementation, regardless of
  79                 /// whether each feature is required or optional.
  80                 const KNOWN_FEATURE_MASK: &'static [u8];
  81         }
  82
  83         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
  84         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
  85         /// feature identifiers.
  86         macro_rules! define_context {
  87                 ($context: ident {
  88                         required_features: [$( $( $required_feature: ident )|*, )*],
  89                         optional_features: [$( $( $optional_feature: ident )|*, )*],
  90                 }) => {
  91                         #[derive(Eq, PartialEq)]
  92                         pub struct $context {}
  93
  94                         impl Context for $context {
  95                                 const KNOWN_FEATURE_FLAGS: &'static [u8] = &[
  96                                         // For each byte, use bitwise-OR to compute the applicable flags for known
  97                                         // required features `r_i` and optional features `o_j` for all `i` and `j` such
  98                                         // that the following slice is formed:
  99                                         //
 100                                         // [
 101                                         //  `r_0` | `r_1` | ... | `o_0` | `o_1` | ...,
 102                                         //  ...,
 103                                         // ]
 104                                         $(
 105                                                 0b00_00_00_00 $(|
 106                                                         <Self as $required_feature>::REQUIRED_MASK)*
 107                                                 $(|
 108                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
 109                                         )*
 110                                 ];
 111
 112                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
 113                                         // Similar as above, but set both flags for each feature regardless of whether
 114                                         // the feature is required or optional.
 115                                         $(
 116                                                 0b00_00_00_00 $(|
 117                                                         <Self as $required_feature>::REQUIRED_MASK |
 118                                                         <Self as $required_feature>::OPTIONAL_MASK)*
 119                                                 $(|
 120                                                         <Self as $optional_feature>::REQUIRED_MASK |
 121                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
 122                                         )*
 123                                 ];
 124                         }
 125
 126                         impl alloc::fmt::Display for Features<$context> {
 127                                 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
 128                                         $(
 129                                                 $(
 130                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($required_feature),
 131                                                                 if <$context as $required_feature>::requires_feature(&self.flags) { "required" }
 132                                                                 else if <$context as $required_feature>::supports_feature(&self.flags) { "supported" }
 133                                                                 else { "not supported" }))?;
 134                                                 )*
 135                                                 $(
 136                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($optional_feature),
 137                                                                 if <$context as $optional_feature>::requires_feature(&self.flags) { "required" }
 138                                                                 else if <$context as $optional_feature>::supports_feature(&self.flags) { "supported" }
 139                                                                 else { "not supported" }))?;
 140                                                 )*
 141                                         )*
 142                                         fmt.write_fmt(format_args!("unknown flags: {}",
 143                                                 if self.requires_unknown_bits() { "required" }
 144                                                 else if self.supports_unknown_bits() { "supported" } else { "none" }))
 145                                 }
 146                         }
 147                 };
 148         }
 149
 150         define_context!(InitContext {
 151                 required_features: [
 152                         // Byte 0
 153                         ,
 154                         // Byte 1
 155                         VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 156                         // Byte 2
 157                         ,
 158                         // Byte 3
 159                         ,
 160                         // Byte 4
 161                         ,
 162                         // Byte 5
 163                         ,
 164                         // Byte 6
 165                         ,
 166                 ],
 167                 optional_features: [
 168                         // Note that if new "non-channel-related" flags are added here they should be
 169                         // explicitly cleared in InitFeatures::known_channel_features and
 170                         // NodeFeatures::known_channel_features.
 171                         // Byte 0
 172                         DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
 173                         // Byte 1
 174                         ,
 175                         // Byte 2
 176                         BasicMPP | Wumbo,
 177                         // Byte 3
 178                         ShutdownAnySegwit,
 179                         // Byte 4
 180                         ,
 181                         // Byte 5
 182                         ChannelType | SCIDPrivacy,
 183                         // Byte 6
 184                         ZeroConf,
 185                 ],
 186         });
 187         define_context!(NodeContext {
 188                 required_features: [
 189                         // Byte 0
 190                         ,
 191                         // Byte 1
 192                         VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 193                         // Byte 2
 194                         ,
 195                         // Byte 3
 196                         ,
 197                         // Byte 4
 198                         ,
 199                         // Byte 5
 200                         ,
 201                         // Byte 6
 202                         ,
 203                 ],
 204                 optional_features: [
 205                         // Byte 0
 206                         DataLossProtect | UpfrontShutdownScript | GossipQueries,
 207                         // Byte 1
 208                         ,
 209                         // Byte 2
 210                         BasicMPP | Wumbo,
 211                         // Byte 3
 212                         ShutdownAnySegwit,
 213                         // Byte 4
 214                         ,
 215                         // Byte 5
 216                         ChannelType | SCIDPrivacy,
 217                         // Byte 6
 218                         ZeroConf | Keysend,
 219                 ],
 220         });
 221         define_context!(ChannelContext {
 222                 required_features: [],
 223                 optional_features: [],
 224         });
 225         define_context!(InvoiceContext {
 226                 required_features: [
 227                         // Byte 0
 228                         ,
 229                         // Byte 1
 230                         VariableLengthOnion | PaymentSecret,
 231                         // Byte 2
 232                         ,
 233                 ],
 234                 optional_features: [
 235                         // Byte 0
 236                         ,
 237                         // Byte 1
 238                         ,
 239                         // Byte 2
 240                         BasicMPP,
 241                 ],
 242         });
 243         // This isn't a "real" feature context, and is only used in the channel_type field in an
 244         // `OpenChannel` message.
 245         define_context!(ChannelTypeContext {
 246                 required_features: [
 247                         // Byte 0
 248                         ,
 249                         // Byte 1
 250                         StaticRemoteKey,
 251                         // Byte 2
 252                         ,
 253                         // Byte 3
 254                         ,
 255                         // Byte 4
 256                         ,
 257                         // Byte 5
 258                         SCIDPrivacy,
 259                         // Byte 6
 260                         ZeroConf,
 261                 ],
 262                 optional_features: [
 263                         // Byte 0
 264                         ,
 265                         // Byte 1
 266                         ,
 267                         // Byte 2
 268                         ,
 269                         // Byte 3
 270                         ,
 271                         // Byte 4
 272                         ,
 273                         // Byte 5
 274                         ,
 275                         // Byte 6
 276                         ,
 277                 ],
 278         });
 279
 280         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
 281         /// useful for manipulating feature flags.
 282         macro_rules! define_feature {
 283                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 284                  $required_setter: ident, $supported_getter: ident) => {
 285                         #[doc = $doc]
 286                         ///
 287                         /// See [BOLT #9] for details.
 288                         ///
 289                         /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 290                         pub trait $feature: Context {
 291                                 /// The bit used to signify that the feature is required.
 292                                 const EVEN_BIT: usize = $odd_bit - 1;
 293
 294                                 /// The bit used to signify that the feature is optional.
 295                                 const ODD_BIT: usize = $odd_bit;
 296
 297                                 /// Assertion that [`EVEN_BIT`] is actually even.
 298                                 ///
 299                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
 300                                 const ASSERT_EVEN_BIT_PARITY: usize;
 301
 302                                 /// Assertion that [`ODD_BIT`] is actually odd.
 303                                 ///
 304                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
 305                                 const ASSERT_ODD_BIT_PARITY: usize;
 306
 307                                 /// The byte where the feature is set.
 308                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
 309
 310                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
 311                                 ///
 312                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 313                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
 314
 315                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
 316                                 ///
 317                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 318                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
 319
 320                                 /// Returns whether the feature is required by the given flags.
 321                                 #[inline]
 322                                 fn requires_feature(flags: &Vec<u8>) -> bool {
 323                                         flags.len() > Self::BYTE_OFFSET &&
 324                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
 325                                 }
 326
 327                                 /// Returns whether the feature is supported by the given flags.
 328                                 #[inline]
 329                                 fn supports_feature(flags: &Vec<u8>) -> bool {
 330                                         flags.len() > Self::BYTE_OFFSET &&
 331                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
 332                                 }
 333
 334                                 /// Sets the feature's required (even) bit in the given flags.
 335                                 #[inline]
 336                                 fn set_required_bit(flags: &mut Vec<u8>) {
 337                                         if flags.len() <= Self::BYTE_OFFSET {
 338                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 339                                         }
 340
 341                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
 342                                 }
 343
 344                                 /// Sets the feature's optional (odd) bit in the given flags.
 345                                 #[inline]
 346                                 fn set_optional_bit(flags: &mut Vec<u8>) {
 347                                         if flags.len() <= Self::BYTE_OFFSET {
 348                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 349                                         }
 350
 351                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
 352                                 }
 353
 354                                 /// Clears the feature's required (even) and optional (odd) bits from the given
 355                                 /// flags.
 356                                 #[inline]
 357                                 fn clear_bits(flags: &mut Vec<u8>) {
 358                                         if flags.len() > Self::BYTE_OFFSET {
 359                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
 360                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 361                                         }
 362
 363                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
 364                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
 365                                         flags.resize(size, 0u8);
 366                                 }
 367                         }
 368
 369                         impl <T: $feature> Features<T> {
 370                                 /// Set this feature as optional.
 371                                 pub fn $optional_setter(&mut self) {
 372                                         <T as $feature>::set_optional_bit(&mut self.flags);
 373                                 }
 374
 375                                 /// Set this feature as required.
 376                                 pub fn $required_setter(&mut self) {
 377                                         <T as $feature>::set_required_bit(&mut self.flags);
 378                                 }
 379
 380                                 /// Checks if this feature is supported.
 381                                 pub fn $supported_getter(&self) -> bool {
 382                                         <T as $feature>::supports_feature(&self.flags)
 383                                 }
 384                         }
 385
 386                         $(
 387                                 impl $feature for $context {
 388                                         // EVEN_BIT % 2 == 0
 389                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
 390
 391                                         // ODD_BIT % 2 == 1
 392                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
 393                                 }
 394                         )*
 395                 };
 396                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 397                  $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
 398                         define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
 399                         impl <T: $feature> Features<T> {
 400                                 /// Checks if this feature is required.
 401                                 pub fn $required_getter(&self) -> bool {
 402                                         <T as $feature>::requires_feature(&self.flags)
 403                                 }
 404                         }
 405                 }
 406         }
 407
 408         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
 409                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
 410                 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
 411         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
 412         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
 413                 set_initial_routing_sync_optional, set_initial_routing_sync_required,
 414                 initial_routing_sync);
 415         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
 416                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
 417                 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
 418                 requires_upfront_shutdown_script);
 419         define_feature!(7, GossipQueries, [InitContext, NodeContext],
 420                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
 421                 supports_gossip_queries, requires_gossip_queries);
 422         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
 423                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
 424                 set_variable_length_onion_required, supports_variable_length_onion,
 425                 requires_variable_length_onion);
 426         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
 427                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
 428                 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
 429         define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
 430                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
 431                 supports_payment_secret, requires_payment_secret);
 432         define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext],
 433                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
 434                 supports_basic_mpp, requires_basic_mpp);
 435         define_feature!(19, Wumbo, [InitContext, NodeContext],
 436                 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
 437                 supports_wumbo, requires_wumbo);
 438         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
 439                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
 440                 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
 441         // We do not yet advertise the onion messages feature bit, but we need to detect when peers
 442         // support it.
 443         define_feature!(39, OnionMessages, [InitContext, NodeContext],
 444                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
 445                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
 446         define_feature!(45, ChannelType, [InitContext, NodeContext],
 447                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
 448                 set_channel_type_required, supports_channel_type, requires_channel_type);
 449         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
 450                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
 451                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
 452         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
 453                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
 454                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
 455         define_feature!(55, Keysend, [NodeContext],
 456                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
 457                 supports_keysend, requires_keysend);
 458
 459         #[cfg(test)]
 460         define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext, InvoiceContext],
 461                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
 462                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
 463 }
 464
 465 /// Tracks the set of features which a node implements, templated by the context in which it
 466 /// appears.
 467 ///
 468 /// (C-not exported) as we map the concrete feature types below directly instead
 469 #[derive(Eq)]
 470 pub struct Features<T: sealed::Context> {
 471         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
 472         flags: Vec<u8>,
 473         mark: PhantomData<T>,
 474 }
 475
 476 impl <T: sealed::Context> Features<T> {
 477         pub(crate) fn or(mut self, o: Self) -> Self {
 478                 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
 479                 self.flags.resize(total_feature_len, 0u8);
 480                 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
 481                         *byte |= *o_byte;
 482                 }
 483                 self
 484         }
 485 }
 486
 487 impl<T: sealed::Context> Clone for Features<T> {
 488         fn clone(&self) -> Self {
 489                 Self {
 490                         flags: self.flags.clone(),
 491                         mark: PhantomData,
 492                 }
 493         }
 494 }
 495 impl<T: sealed::Context> Hash for Features<T> {
 496         fn hash<H: Hasher>(&self, hasher: &mut H) {
 497                 self.flags.hash(hasher);
 498         }
 499 }
 500 impl<T: sealed::Context> PartialEq for Features<T> {
 501         fn eq(&self, o: &Self) -> bool {
 502                 self.flags.eq(&o.flags)
 503         }
 504 }
 505 impl<T: sealed::Context> fmt::Debug for Features<T> {
 506         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 507                 self.flags.fmt(fmt)
 508         }
 509 }
 510
 511 /// Features used within an `init` message.
 512 pub type InitFeatures = Features<sealed::InitContext>;
 513 /// Features used within a `node_announcement` message.
 514 pub type NodeFeatures = Features<sealed::NodeContext>;
 515 /// Features used within a `channel_announcement` message.
 516 pub type ChannelFeatures = Features<sealed::ChannelContext>;
 517 /// Features used within an invoice.
 518 pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
 519
 520 /// Features used within the channel_type field in an OpenChannel message.
 521 ///
 522 /// A channel is always of some known "type", describing the transaction formats used and the exact
 523 /// semantics of our interaction with our peer.
 524 ///
 525 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
 526 /// the counterparty, only required features are allowed here.
 527 ///
 528 /// This is serialized differently from other feature types - it is not prefixed by a length, and
 529 /// thus must only appear inside a TLV where its length is known in advance.
 530 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
 531
 532 impl InitFeatures {
 533         /// Writes all features present up to, and including, 13.
 534         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 535                 let len = cmp::min(2, self.flags.len());
 536                 (len as u16).write(w)?;
 537                 for i in (0..len).rev() {
 538                         if i == 0 {
 539                                 self.flags[i].write(w)?;
 540                         } else {
 541                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
 542                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
 543                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
 544                         }
 545                 }
 546                 Ok(())
 547         }
 548
 549         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
 550         /// are included in the result.
 551         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 552                 self.to_context_internal()
 553         }
 554
 555         /// Returns the set of known init features that are related to channels. At least some of
 556         /// these features are likely required for peers to talk to us.
 557         pub fn known_channel_features() -> InitFeatures {
 558                 Self::known()
 559                         .clear_initial_routing_sync()
 560                         .clear_gossip_queries()
 561         }
 562 }
 563
 564 impl NodeFeatures {
 565         /// Returns the set of known node features that are related to channels.
 566         pub fn known_channel_features() -> NodeFeatures {
 567                 Self::known().clear_gossip_queries()
 568         }
 569 }
 570
 571 impl InvoiceFeatures {
 572         /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
 573         /// context `C` are included in the result.
 574         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 575                 self.to_context_internal()
 576         }
 577
 578         /// Getting a route for a keysend payment to a private node requires providing the payee's
 579         /// features (since they were not announced in a node announcement). However, keysend payments
 580         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
 581         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
 582         /// `InvoiceFeatures` for [`find_route`].
 583         ///
 584         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
 585         /// [`find_route`]: crate::routing::router::find_route
 586         pub(crate) fn for_keysend() -> InvoiceFeatures {
 587                 let mut res = InvoiceFeatures::empty();
 588                 res.set_variable_length_onion_optional();
 589                 res
 590         }
 591 }
 592
 593 impl ChannelTypeFeatures {
 594         /// Constructs the implicit channel type based on the common supported types between us and our
 595         /// counterparty
 596         pub(crate) fn from_counterparty_init(counterparty_init: &InitFeatures) -> Self {
 597                 let mut ret = counterparty_init.to_context_internal();
 598                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
 599                 // optional bits and then AND out the optional ones.
 600                 for byte in ret.flags.iter_mut() {
 601                         *byte |= (*byte & 0b10_10_10_10) >> 1;
 602                         *byte &= 0b01_01_01_01;
 603                 }
 604                 ret
 605         }
 606
 607         /// Constructs a ChannelTypeFeatures with only static_remotekey set
 608         pub(crate) fn only_static_remote_key() -> Self {
 609                 let mut ret = Self::empty();
 610                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
 611                 ret
 612         }
 613 }
 614
 615 impl ToBase32 for InvoiceFeatures {
 616         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
 617                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
 618                 // minus one before dividing
 619                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
 620                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
 621                 for (byte_idx, byte) in self.flags.iter().enumerate() {
 622                         let bit_pos_from_left_0_indexed = byte_idx * 8;
 623                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
 624                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
 625                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
 626                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
 627                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
 628                         if new_u5_idx > 0 {
 629                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
 630                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
 631                         }
 632                         if new_u5_idx > 1 {
 633                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
 634                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
 635                         }
 636                 }
 637                 // Trim the highest feature bits.
 638                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
 639                         res_u5s.remove(0);
 640                 }
 641                 writer.write(&res_u5s)
 642         }
 643 }
 644
 645 impl Base32Len for InvoiceFeatures {
 646         fn base32_len(&self) -> usize {
 647                 self.to_base32().len()
 648         }
 649 }
 650
 651 impl FromBase32 for InvoiceFeatures {
 652         type Err = bech32::Error;
 653
 654         fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
 655                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
 656                 // minus one before dividing
 657                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
 658                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
 659                 for (u5_idx, chunk) in field_data.iter().enumerate() {
 660                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
 661                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
 662                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
 663                         let chunk_u16 = chunk.to_u8() as u16;
 664                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
 665                         if new_byte_idx != length_bytes - 1 {
 666                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
 667                         }
 668                 }
 669                 // Trim the highest feature bits.
 670                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
 671                         res_bytes.pop();
 672                 }
 673                 Ok(InvoiceFeatures::from_le_bytes(res_bytes))
 674         }
 675 }
 676
 677 impl<T: sealed::Context> Features<T> {
 678         /// Create a blank Features with no features set
 679         pub fn empty() -> Self {
 680                 Features {
 681                         flags: Vec::new(),
 682                         mark: PhantomData,
 683                 }
 684         }
 685
 686         /// Creates a Features with the bits set which are known by the implementation
 687         pub fn known() -> Self {
 688                 Self {
 689                         flags: T::KNOWN_FEATURE_FLAGS.to_vec(),
 690                         mark: PhantomData,
 691                 }
 692         }
 693
 694         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
 695         /// included in the result.
 696         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
 697                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
 698                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
 699                 let mut flags = Vec::new();
 700                 for (i, byte) in self.flags.iter().enumerate() {
 701                         if i < from_byte_count && i < to_byte_count {
 702                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
 703                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
 704                                 flags.push(byte & from_known_features & to_known_features);
 705                         }
 706                 }
 707                 Features::<C> { flags, mark: PhantomData, }
 708         }
 709
 710         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
 711         /// most on-the-wire encodings.
 712         /// (C-not exported) as we don't support export across multiple T
 713         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 714                 Features {
 715                         flags,
 716                         mark: PhantomData,
 717                 }
 718         }
 719
 720         #[cfg(test)]
 721         /// Gets the underlying flags set, in LE.
 722         pub fn le_flags(&self) -> &Vec<u8> {
 723                 &self.flags
 724         }
 725
 726         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 727                 for f in self.flags.iter().rev() { // Swap back to big-endian
 728                         f.write(w)?;
 729                 }
 730                 Ok(())
 731         }
 732
 733         fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
 734                 flags.reverse(); // Swap to little-endian
 735                 Self {
 736                         flags,
 737                         mark: PhantomData,
 738                 }
 739         }
 740
 741         pub(crate) fn supports_any_optional_bits(&self) -> bool {
 742                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
 743         }
 744
 745         /// Returns true if this `Features` object contains unknown feature flags which are set as
 746         /// "required".
 747         pub fn requires_unknown_bits(&self) -> bool {
 748                 // Bitwise AND-ing with all even bits set except for known features will select required
 749                 // unknown features.
 750                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 751                 self.flags.iter().enumerate().any(|(i, &byte)| {
 752                         let required_features = 0b01_01_01_01;
 753                         let unknown_features = if i < byte_count {
 754                                 !T::KNOWN_FEATURE_MASK[i]
 755                         } else {
 756                                 0b11_11_11_11
 757                         };
 758                         (byte & (required_features & unknown_features)) != 0
 759                 })
 760         }
 761
 762         pub(crate) fn supports_unknown_bits(&self) -> bool {
 763                 // Bitwise AND-ing with all even and odd bits set except for known features will select
 764                 // both required and optional unknown features.
 765                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 766                 self.flags.iter().enumerate().any(|(i, &byte)| {
 767                         let unknown_features = if i < byte_count {
 768                                 !T::KNOWN_FEATURE_MASK[i]
 769                         } else {
 770                                 0b11_11_11_11
 771                         };
 772                         (byte & unknown_features) != 0
 773                 })
 774         }
 775 }
 776
 777 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 778         #[cfg(test)]
 779         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
 780                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
 781                 self
 782         }
 783 }
 784
 785
 786 impl<T: sealed::GossipQueries> Features<T> {
 787         pub(crate) fn clear_gossip_queries(mut self) -> Self {
 788                 <T as sealed::GossipQueries>::clear_bits(&mut self.flags);
 789                 self
 790         }
 791 }
 792
 793 impl<T: sealed::InitialRoutingSync> Features<T> {
 794         // Note that initial_routing_sync is ignored if gossip_queries is set.
 795         pub(crate) fn clear_initial_routing_sync(mut self) -> Self {
 796                 <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags);
 797                 self
 798         }
 799 }
 800
 801 impl<T: sealed::ShutdownAnySegwit> Features<T> {
 802         #[cfg(test)]
 803         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
 804                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
 805                 self
 806         }
 807 }
 808
 809 impl<T: sealed::Wumbo> Features<T> {
 810         #[cfg(test)]
 811         pub(crate) fn clear_wumbo(mut self) -> Self {
 812                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
 813                 self
 814         }
 815 }
 816
 817 macro_rules! impl_feature_len_prefixed_write {
 818         ($features: ident) => {
 819                 impl Writeable for $features {
 820                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 821                                 (self.flags.len() as u16).write(w)?;
 822                                 self.write_be(w)
 823                         }
 824                 }
 825                 impl Readable for $features {
 826                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 827                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
 828                         }
 829                 }
 830         }
 831 }
 832 impl_feature_len_prefixed_write!(InitFeatures);
 833 impl_feature_len_prefixed_write!(ChannelFeatures);
 834 impl_feature_len_prefixed_write!(NodeFeatures);
 835 impl_feature_len_prefixed_write!(InvoiceFeatures);
 836
 837 // Because ChannelTypeFeatures only appears inside of TLVs, it doesn't have a length prefix when
 838 // serialized. Thus, we can't use `impl_feature_len_prefixed_write`, above, and have to write our
 839 // own serialization.
 840 impl Writeable for ChannelTypeFeatures {
 841         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 842                 self.write_be(w)
 843         }
 844 }
 845 impl Readable for ChannelTypeFeatures {
 846         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 847                 let v = io_extras::read_to_end(r)?;
 848                 Ok(Self::from_be_bytes(v))
 849         }
 850 }
 851
 852 #[cfg(test)]
 853 mod tests {
 854         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
 855         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
 856
 857         #[test]
 858         fn sanity_test_known_features() {
 859                 assert!(!ChannelFeatures::known().requires_unknown_bits());
 860                 assert!(!ChannelFeatures::known().supports_unknown_bits());
 861                 assert!(!InitFeatures::known().requires_unknown_bits());
 862                 assert!(!InitFeatures::known().supports_unknown_bits());
 863                 assert!(!NodeFeatures::known().requires_unknown_bits());
 864                 assert!(!NodeFeatures::known().supports_unknown_bits());
 865
 866                 assert!(InitFeatures::known().supports_upfront_shutdown_script());
 867                 assert!(NodeFeatures::known().supports_upfront_shutdown_script());
 868                 assert!(!InitFeatures::known().requires_upfront_shutdown_script());
 869                 assert!(!NodeFeatures::known().requires_upfront_shutdown_script());
 870
 871                 assert!(InitFeatures::known().supports_gossip_queries());
 872                 assert!(NodeFeatures::known().supports_gossip_queries());
 873                 assert!(!InitFeatures::known().requires_gossip_queries());
 874                 assert!(!NodeFeatures::known().requires_gossip_queries());
 875
 876                 assert!(InitFeatures::known().supports_data_loss_protect());
 877                 assert!(NodeFeatures::known().supports_data_loss_protect());
 878                 assert!(!InitFeatures::known().requires_data_loss_protect());
 879                 assert!(!NodeFeatures::known().requires_data_loss_protect());
 880
 881                 assert!(InitFeatures::known().supports_variable_length_onion());
 882                 assert!(NodeFeatures::known().supports_variable_length_onion());
 883                 assert!(InvoiceFeatures::known().supports_variable_length_onion());
 884                 assert!(InitFeatures::known().requires_variable_length_onion());
 885                 assert!(NodeFeatures::known().requires_variable_length_onion());
 886                 assert!(InvoiceFeatures::known().requires_variable_length_onion());
 887
 888                 assert!(InitFeatures::known().supports_static_remote_key());
 889                 assert!(NodeFeatures::known().supports_static_remote_key());
 890                 assert!(InitFeatures::known().requires_static_remote_key());
 891                 assert!(NodeFeatures::known().requires_static_remote_key());
 892
 893                 assert!(InitFeatures::known().supports_payment_secret());
 894                 assert!(NodeFeatures::known().supports_payment_secret());
 895                 assert!(InvoiceFeatures::known().supports_payment_secret());
 896                 assert!(InitFeatures::known().requires_payment_secret());
 897                 assert!(NodeFeatures::known().requires_payment_secret());
 898                 assert!(InvoiceFeatures::known().requires_payment_secret());
 899
 900                 assert!(InitFeatures::known().supports_basic_mpp());
 901                 assert!(NodeFeatures::known().supports_basic_mpp());
 902                 assert!(InvoiceFeatures::known().supports_basic_mpp());
 903                 assert!(!InitFeatures::known().requires_basic_mpp());
 904                 assert!(!NodeFeatures::known().requires_basic_mpp());
 905                 assert!(!InvoiceFeatures::known().requires_basic_mpp());
 906
 907                 assert!(InitFeatures::known().supports_channel_type());
 908                 assert!(NodeFeatures::known().supports_channel_type());
 909                 assert!(!InitFeatures::known().requires_channel_type());
 910                 assert!(!NodeFeatures::known().requires_channel_type());
 911
 912                 assert!(InitFeatures::known().supports_shutdown_anysegwit());
 913                 assert!(NodeFeatures::known().supports_shutdown_anysegwit());
 914
 915                 assert!(InitFeatures::known().supports_scid_privacy());
 916                 assert!(NodeFeatures::known().supports_scid_privacy());
 917                 assert!(ChannelTypeFeatures::known().supports_scid_privacy());
 918                 assert!(!InitFeatures::known().requires_scid_privacy());
 919                 assert!(!NodeFeatures::known().requires_scid_privacy());
 920                 assert!(ChannelTypeFeatures::known().requires_scid_privacy());
 921
 922                 assert!(InitFeatures::known().supports_wumbo());
 923                 assert!(NodeFeatures::known().supports_wumbo());
 924                 assert!(!InitFeatures::known().requires_wumbo());
 925                 assert!(!NodeFeatures::known().requires_wumbo());
 926
 927                 assert!(InitFeatures::known().supports_zero_conf());
 928                 assert!(!InitFeatures::known().requires_zero_conf());
 929                 assert!(NodeFeatures::known().supports_zero_conf());
 930                 assert!(!NodeFeatures::known().requires_zero_conf());
 931                 assert!(ChannelTypeFeatures::known().supports_zero_conf());
 932                 assert!(ChannelTypeFeatures::known().requires_zero_conf());
 933
 934                 let mut init_features = InitFeatures::known();
 935                 assert!(init_features.initial_routing_sync());
 936                 init_features = init_features.clear_initial_routing_sync();
 937                 assert!(!init_features.initial_routing_sync());
 938         }
 939
 940         #[test]
 941         fn sanity_test_unknown_bits() {
 942                 let features = ChannelFeatures::empty();
 943                 assert!(!features.requires_unknown_bits());
 944                 assert!(!features.supports_unknown_bits());
 945
 946                 let mut features = ChannelFeatures::empty();
 947                 features.set_unknown_feature_required();
 948                 assert!(features.requires_unknown_bits());
 949                 assert!(features.supports_unknown_bits());
 950
 951                 let mut features = ChannelFeatures::empty();
 952                 features.set_unknown_feature_optional();
 953                 assert!(!features.requires_unknown_bits());
 954                 assert!(features.supports_unknown_bits());
 955         }
 956
 957         #[test]
 958         fn convert_to_context_with_relevant_flags() {
 959                 let init_features = InitFeatures::known().clear_upfront_shutdown_script().clear_gossip_queries();
 960                 assert!(init_features.initial_routing_sync());
 961                 assert!(!init_features.supports_upfront_shutdown_script());
 962                 assert!(!init_features.supports_gossip_queries());
 963
 964                 let node_features: NodeFeatures = init_features.to_context();
 965                 {
 966                         // Check that the flags are as expected:
 967                         // - option_data_loss_protect
 968                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
 969                         // - basic_mpp | wumbo
 970                         // - opt_shutdown_anysegwit
 971                         // -
 972                         // - option_channel_type | option_scid_alias
 973                         // - option_zeroconf
 974                         assert_eq!(node_features.flags.len(), 7);
 975                         assert_eq!(node_features.flags[0], 0b00000010);
 976                         assert_eq!(node_features.flags[1], 0b01010001);
 977                         assert_eq!(node_features.flags[2], 0b00001010);
 978                         assert_eq!(node_features.flags[3], 0b00001000);
 979                         assert_eq!(node_features.flags[4], 0b00000000);
 980                         assert_eq!(node_features.flags[5], 0b10100000);
 981                         assert_eq!(node_features.flags[6], 0b00001000);
 982                 }
 983
 984                 // Check that cleared flags are kept blank when converting back:
 985                 // - initial_routing_sync was not applicable to NodeContext
 986                 // - upfront_shutdown_script was cleared before converting
 987                 // - gossip_queries was cleared before converting
 988                 let features: InitFeatures = node_features.to_context_internal();
 989                 assert!(!features.initial_routing_sync());
 990                 assert!(!features.supports_upfront_shutdown_script());
 991                 assert!(!init_features.supports_gossip_queries());
 992         }
 993
 994         #[test]
 995         fn convert_to_context_with_unknown_flags() {
 996                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
 997                 assert!(InvoiceFeatures::known().flags.len() < NodeFeatures::known().flags.len());
 998                 let mut invoice_features = InvoiceFeatures::known();
 999                 invoice_features.set_unknown_feature_optional();
1000                 assert!(invoice_features.supports_unknown_bits());
1001                 let node_features: NodeFeatures = invoice_features.to_context();
1002                 assert!(!node_features.supports_unknown_bits());
1003         }
1004
1005         #[test]
1006         fn set_feature_bits() {
1007                 let mut features = InvoiceFeatures::empty();
1008                 features.set_basic_mpp_optional();
1009                 features.set_payment_secret_required();
1010                 assert!(features.supports_basic_mpp());
1011                 assert!(!features.requires_basic_mpp());
1012                 assert!(features.requires_payment_secret());
1013                 assert!(features.supports_payment_secret());
1014         }
1015
1016         #[test]
1017         fn invoice_features_encoding() {
1018                 let features_as_u5s = vec![
1019                         u5::try_from_u8(6).unwrap(),
1020                         u5::try_from_u8(10).unwrap(),
1021                         u5::try_from_u8(25).unwrap(),
1022                         u5::try_from_u8(1).unwrap(),
1023                         u5::try_from_u8(10).unwrap(),
1024                         u5::try_from_u8(0).unwrap(),
1025                         u5::try_from_u8(20).unwrap(),
1026                         u5::try_from_u8(2).unwrap(),
1027                         u5::try_from_u8(0).unwrap(),
1028                         u5::try_from_u8(6).unwrap(),
1029                         u5::try_from_u8(0).unwrap(),
1030                         u5::try_from_u8(16).unwrap(),
1031                         u5::try_from_u8(1).unwrap(),
1032                 ];
1033                 let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1034
1035                 // Test length calculation.
1036                 assert_eq!(features.base32_len(), 13);
1037
1038                 // Test serialization.
1039                 let features_serialized = features.to_base32();
1040                 assert_eq!(features_as_u5s, features_serialized);
1041
1042                 // Test deserialization.
1043                 let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1044                 assert_eq!(features, features_deserialized);
1045         }
1046
1047         #[test]
1048         fn test_channel_type_mapping() {
1049                 // If we map an InvoiceFeatures with StaticRemoteKey optional, it should map into a
1050                 // required-StaticRemoteKey ChannelTypeFeatures.
1051                 let mut init_features = InitFeatures::empty();
1052                 init_features.set_static_remote_key_optional();
1053                 let converted_features = ChannelTypeFeatures::from_counterparty_init(&init_features);
1054                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1055                 assert!(!converted_features.supports_any_optional_bits());
1056                 assert!(converted_features.requires_static_remote_key());
1057         }
1058 }