_ 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 //! - `OnionMessages` - requires/supports forwarding onion messages
  47 //!     (see [BOLT-7](https://github.com/lightning/bolts/pull/759/files) for more information).
  48 //!     TODO: update link
  49 //! - `ChannelType` - node supports the channel_type field in open/accept
  50 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  51 //! - `SCIDPrivacy` - supply channel aliases for routing
  52 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  53 //! - `Keysend` - send funds to a node without an invoice
  54 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
  55 //!
  56 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
  57 //! [messages]: crate::ln::msgs
  58
  59 use {io, io_extras};
  60 use prelude::*;
  61 use core::{cmp, fmt};
  62 use core::hash::{Hash, Hasher};
  63 use core::marker::PhantomData;
  64
  65 use bitcoin::bech32;
  66 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
  67 use ln::msgs::DecodeError;
  68 use util::ser::{Readable, Writeable, Writer};
  69
  70 mod sealed {
  71         use prelude::*;
  72         use ln::features::Features;
  73
  74         /// The context in which [`Features`] are applicable. Defines which features are required and
  75         /// which are optional for the context.
  76         pub trait Context {
  77                 /// Features that are known to the implementation, where a required feature is indicated by
  78                 /// its even bit and an optional feature is indicated by its odd bit.
  79                 const KNOWN_FEATURE_FLAGS: &'static [u8];
  80
  81                 /// Bitmask for selecting features that are known to the implementation, regardless of
  82                 /// whether each feature is required or optional.
  83                 const KNOWN_FEATURE_MASK: &'static [u8];
  84         }
  85
  86         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
  87         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
  88         /// feature identifiers.
  89         macro_rules! define_context {
  90                 ($context: ident {
  91                         required_features: [$( $( $required_feature: ident )|*, )*],
  92                         optional_features: [$( $( $optional_feature: ident )|*, )*],
  93                 }) => {
  94                         #[derive(Eq, PartialEq)]
  95                         pub struct $context {}
  96
  97                         impl Context for $context {
  98                                 const KNOWN_FEATURE_FLAGS: &'static [u8] = &[
  99                                         // For each byte, use bitwise-OR to compute the applicable flags for known
 100                                         // required features `r_i` and optional features `o_j` for all `i` and `j` such
 101                                         // that the following slice is formed:
 102                                         //
 103                                         // [
 104                                         //  `r_0` | `r_1` | ... | `o_0` | `o_1` | ...,
 105                                         //  ...,
 106                                         // ]
 107                                         $(
 108                                                 0b00_00_00_00 $(|
 109                                                         <Self as $required_feature>::REQUIRED_MASK)*
 110                                                 $(|
 111                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
 112                                         )*
 113                                 ];
 114
 115                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
 116                                         // Similar as above, but set both flags for each feature regardless of whether
 117                                         // the feature is required or optional.
 118                                         $(
 119                                                 0b00_00_00_00 $(|
 120                                                         <Self as $required_feature>::REQUIRED_MASK |
 121                                                         <Self as $required_feature>::OPTIONAL_MASK)*
 122                                                 $(|
 123                                                         <Self as $optional_feature>::REQUIRED_MASK |
 124                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
 125                                         )*
 126                                 ];
 127                         }
 128
 129                         impl alloc::fmt::Display for Features<$context> {
 130                                 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
 131                                         $(
 132                                                 $(
 133                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($required_feature),
 134                                                                 if <$context as $required_feature>::requires_feature(&self.flags) { "required" }
 135                                                                 else if <$context as $required_feature>::supports_feature(&self.flags) { "supported" }
 136                                                                 else { "not supported" }))?;
 137                                                 )*
 138                                                 $(
 139                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($optional_feature),
 140                                                                 if <$context as $optional_feature>::requires_feature(&self.flags) { "required" }
 141                                                                 else if <$context as $optional_feature>::supports_feature(&self.flags) { "supported" }
 142                                                                 else { "not supported" }))?;
 143                                                 )*
 144                                         )*
 145                                         fmt.write_fmt(format_args!("unknown flags: {}",
 146                                                 if self.requires_unknown_bits() { "required" }
 147                                                 else if self.supports_unknown_bits() { "supported" } else { "none" }))
 148                                 }
 149                         }
 150                 };
 151         }
 152
 153         define_context!(InitContext {
 154                 required_features: [
 155                         // Byte 0
 156                         ,
 157                         // Byte 1
 158                         VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 159                         // Byte 2
 160                         ,
 161                         // Byte 3
 162                         ,
 163                         // Byte 4
 164                         ,
 165                         // Byte 5
 166                         ,
 167                         // Byte 6
 168                         ,
 169                 ],
 170                 optional_features: [
 171                         // Note that if new "non-channel-related" flags are added here they should be
 172                         // explicitly cleared in InitFeatures::known_channel_features and
 173                         // NodeFeatures::known_channel_features.
 174                         // Byte 0
 175                         DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
 176                         // Byte 1
 177                         ,
 178                         // Byte 2
 179                         BasicMPP | Wumbo,
 180                         // Byte 3
 181                         ShutdownAnySegwit,
 182                         // Byte 4
 183                         OnionMessages,
 184                         // Byte 5
 185                         ChannelType | SCIDPrivacy,
 186                         // Byte 6
 187                         ZeroConf,
 188                 ],
 189         });
 190         define_context!(NodeContext {
 191                 required_features: [
 192                         // Byte 0
 193                         ,
 194                         // Byte 1
 195                         VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 196                         // Byte 2
 197                         ,
 198                         // Byte 3
 199                         ,
 200                         // Byte 4
 201                         ,
 202                         // Byte 5
 203                         ,
 204                         // Byte 6
 205                         ,
 206                 ],
 207                 optional_features: [
 208                         // Byte 0
 209                         DataLossProtect | UpfrontShutdownScript | GossipQueries,
 210                         // Byte 1
 211                         ,
 212                         // Byte 2
 213                         BasicMPP | Wumbo,
 214                         // Byte 3
 215                         ShutdownAnySegwit,
 216                         // Byte 4
 217                         OnionMessages,
 218                         // Byte 5
 219                         ChannelType | SCIDPrivacy,
 220                         // Byte 6
 221                         ZeroConf | Keysend,
 222                 ],
 223         });
 224         define_context!(ChannelContext {
 225                 required_features: [],
 226                 optional_features: [],
 227         });
 228         define_context!(InvoiceContext {
 229                 required_features: [
 230                         // Byte 0
 231                         ,
 232                         // Byte 1
 233                         VariableLengthOnion | PaymentSecret,
 234                         // Byte 2
 235                         ,
 236                 ],
 237                 optional_features: [
 238                         // Byte 0
 239                         ,
 240                         // Byte 1
 241                         ,
 242                         // Byte 2
 243                         BasicMPP,
 244                 ],
 245         });
 246         // This isn't a "real" feature context, and is only used in the channel_type field in an
 247         // `OpenChannel` message.
 248         define_context!(ChannelTypeContext {
 249                 required_features: [
 250                         // Byte 0
 251                         ,
 252                         // Byte 1
 253                         StaticRemoteKey,
 254                         // Byte 2
 255                         ,
 256                         // Byte 3
 257                         ,
 258                         // Byte 4
 259                         ,
 260                         // Byte 5
 261                         SCIDPrivacy,
 262                         // Byte 6
 263                         ZeroConf,
 264                 ],
 265                 optional_features: [
 266                         // Byte 0
 267                         ,
 268                         // Byte 1
 269                         ,
 270                         // Byte 2
 271                         ,
 272                         // Byte 3
 273                         ,
 274                         // Byte 4
 275                         ,
 276                         // Byte 5
 277                         ,
 278                         // Byte 6
 279                         ,
 280                 ],
 281         });
 282
 283         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
 284         /// useful for manipulating feature flags.
 285         macro_rules! define_feature {
 286                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 287                  $required_setter: ident, $supported_getter: ident) => {
 288                         #[doc = $doc]
 289                         ///
 290                         /// See [BOLT #9] for details.
 291                         ///
 292                         /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 293                         pub trait $feature: Context {
 294                                 /// The bit used to signify that the feature is required.
 295                                 const EVEN_BIT: usize = $odd_bit - 1;
 296
 297                                 /// The bit used to signify that the feature is optional.
 298                                 const ODD_BIT: usize = $odd_bit;
 299
 300                                 /// Assertion that [`EVEN_BIT`] is actually even.
 301                                 ///
 302                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
 303                                 const ASSERT_EVEN_BIT_PARITY: usize;
 304
 305                                 /// Assertion that [`ODD_BIT`] is actually odd.
 306                                 ///
 307                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
 308                                 const ASSERT_ODD_BIT_PARITY: usize;
 309
 310                                 /// The byte where the feature is set.
 311                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
 312
 313                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
 314                                 ///
 315                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 316                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
 317
 318                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
 319                                 ///
 320                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 321                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
 322
 323                                 /// Returns whether the feature is required by the given flags.
 324                                 #[inline]
 325                                 fn requires_feature(flags: &Vec<u8>) -> bool {
 326                                         flags.len() > Self::BYTE_OFFSET &&
 327                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
 328                                 }
 329
 330                                 /// Returns whether the feature is supported by the given flags.
 331                                 #[inline]
 332                                 fn supports_feature(flags: &Vec<u8>) -> bool {
 333                                         flags.len() > Self::BYTE_OFFSET &&
 334                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
 335                                 }
 336
 337                                 /// Sets the feature's required (even) bit in the given flags.
 338                                 #[inline]
 339                                 fn set_required_bit(flags: &mut Vec<u8>) {
 340                                         if flags.len() <= Self::BYTE_OFFSET {
 341                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 342                                         }
 343
 344                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
 345                                 }
 346
 347                                 /// Sets the feature's optional (odd) bit in the given flags.
 348                                 #[inline]
 349                                 fn set_optional_bit(flags: &mut Vec<u8>) {
 350                                         if flags.len() <= Self::BYTE_OFFSET {
 351                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 352                                         }
 353
 354                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
 355                                 }
 356
 357                                 /// Clears the feature's required (even) and optional (odd) bits from the given
 358                                 /// flags.
 359                                 #[inline]
 360                                 fn clear_bits(flags: &mut Vec<u8>) {
 361                                         if flags.len() > Self::BYTE_OFFSET {
 362                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
 363                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 364                                         }
 365
 366                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
 367                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
 368                                         flags.resize(size, 0u8);
 369                                 }
 370                         }
 371
 372                         impl <T: $feature> Features<T> {
 373                                 /// Set this feature as optional.
 374                                 pub fn $optional_setter(&mut self) {
 375                                         <T as $feature>::set_optional_bit(&mut self.flags);
 376                                 }
 377
 378                                 /// Set this feature as required.
 379                                 pub fn $required_setter(&mut self) {
 380                                         <T as $feature>::set_required_bit(&mut self.flags);
 381                                 }
 382
 383                                 /// Checks if this feature is supported.
 384                                 pub fn $supported_getter(&self) -> bool {
 385                                         <T as $feature>::supports_feature(&self.flags)
 386                                 }
 387                         }
 388
 389                         $(
 390                                 impl $feature for $context {
 391                                         // EVEN_BIT % 2 == 0
 392                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
 393
 394                                         // ODD_BIT % 2 == 1
 395                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
 396                                 }
 397                         )*
 398                 };
 399                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 400                  $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
 401                         define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
 402                         impl <T: $feature> Features<T> {
 403                                 /// Checks if this feature is required.
 404                                 pub fn $required_getter(&self) -> bool {
 405                                         <T as $feature>::requires_feature(&self.flags)
 406                                 }
 407                         }
 408                 }
 409         }
 410
 411         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
 412                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
 413                 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
 414         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
 415         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
 416                 set_initial_routing_sync_optional, set_initial_routing_sync_required,
 417                 initial_routing_sync);
 418         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
 419                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
 420                 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
 421                 requires_upfront_shutdown_script);
 422         define_feature!(7, GossipQueries, [InitContext, NodeContext],
 423                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
 424                 supports_gossip_queries, requires_gossip_queries);
 425         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
 426                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
 427                 set_variable_length_onion_required, supports_variable_length_onion,
 428                 requires_variable_length_onion);
 429         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
 430                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
 431                 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
 432         define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
 433                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
 434                 supports_payment_secret, requires_payment_secret);
 435         define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext],
 436                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
 437                 supports_basic_mpp, requires_basic_mpp);
 438         define_feature!(19, Wumbo, [InitContext, NodeContext],
 439                 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
 440                 supports_wumbo, requires_wumbo);
 441         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
 442                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
 443                 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
 444         define_feature!(39, OnionMessages, [InitContext, NodeContext],
 445                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
 446                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
 447         define_feature!(45, ChannelType, [InitContext, NodeContext],
 448                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
 449                 set_channel_type_required, supports_channel_type, requires_channel_type);
 450         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
 451                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
 452                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
 453         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
 454                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
 455                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
 456         define_feature!(55, Keysend, [NodeContext],
 457                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
 458                 supports_keysend, requires_keysend);
 459
 460         #[cfg(test)]
 461         define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext, InvoiceContext],
 462                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
 463                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
 464 }
 465
 466 /// Tracks the set of features which a node implements, templated by the context in which it
 467 /// appears.
 468 ///
 469 /// (C-not exported) as we map the concrete feature types below directly instead
 470 #[derive(Eq)]
 471 pub struct Features<T: sealed::Context> {
 472         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
 473         flags: Vec<u8>,
 474         mark: PhantomData<T>,
 475 }
 476
 477 impl <T: sealed::Context> Features<T> {
 478         pub(crate) fn or(mut self, o: Self) -> Self {
 479                 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
 480                 self.flags.resize(total_feature_len, 0u8);
 481                 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
 482                         *byte |= *o_byte;
 483                 }
 484                 self
 485         }
 486 }
 487
 488 impl<T: sealed::Context> Clone for Features<T> {
 489         fn clone(&self) -> Self {
 490                 Self {
 491                         flags: self.flags.clone(),
 492                         mark: PhantomData,
 493                 }
 494         }
 495 }
 496 impl<T: sealed::Context> Hash for Features<T> {
 497         fn hash<H: Hasher>(&self, hasher: &mut H) {
 498                 self.flags.hash(hasher);
 499         }
 500 }
 501 impl<T: sealed::Context> PartialEq for Features<T> {
 502         fn eq(&self, o: &Self) -> bool {
 503                 self.flags.eq(&o.flags)
 504         }
 505 }
 506 impl<T: sealed::Context> fmt::Debug for Features<T> {
 507         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 508                 self.flags.fmt(fmt)
 509         }
 510 }
 511
 512 /// Features used within an `init` message.
 513 pub type InitFeatures = Features<sealed::InitContext>;
 514 /// Features used within a `node_announcement` message.
 515 pub type NodeFeatures = Features<sealed::NodeContext>;
 516 /// Features used within a `channel_announcement` message.
 517 pub type ChannelFeatures = Features<sealed::ChannelContext>;
 518 /// Features used within an invoice.
 519 pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
 520
 521 /// Features used within the channel_type field in an OpenChannel message.
 522 ///
 523 /// A channel is always of some known "type", describing the transaction formats used and the exact
 524 /// semantics of our interaction with our peer.
 525 ///
 526 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
 527 /// the counterparty, only required features are allowed here.
 528 ///
 529 /// This is serialized differently from other feature types - it is not prefixed by a length, and
 530 /// thus must only appear inside a TLV where its length is known in advance.
 531 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
 532
 533 impl InitFeatures {
 534         /// Writes all features present up to, and including, 13.
 535         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 536                 let len = cmp::min(2, self.flags.len());
 537                 (len as u16).write(w)?;
 538                 for i in (0..len).rev() {
 539                         if i == 0 {
 540                                 self.flags[i].write(w)?;
 541                         } else {
 542                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
 543                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
 544                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
 545                         }
 546                 }
 547                 Ok(())
 548         }
 549
 550         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
 551         /// are included in the result.
 552         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 553                 self.to_context_internal()
 554         }
 555
 556         /// Returns the set of known init features that are related to channels. At least some of
 557         /// these features are likely required for peers to talk to us.
 558         pub fn known_channel_features() -> InitFeatures {
 559                 Self::known()
 560                         .clear_initial_routing_sync()
 561                         .clear_gossip_queries()
 562         }
 563 }
 564
 565 impl NodeFeatures {
 566         /// Returns the set of known node features that are related to channels.
 567         pub fn known_channel_features() -> NodeFeatures {
 568                 Self::known().clear_gossip_queries()
 569         }
 570 }
 571
 572 impl InvoiceFeatures {
 573         /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
 574         /// context `C` are included in the result.
 575         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 576                 self.to_context_internal()
 577         }
 578
 579         /// Getting a route for a keysend payment to a private node requires providing the payee's
 580         /// features (since they were not announced in a node announcement). However, keysend payments
 581         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
 582         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
 583         /// `InvoiceFeatures` for [`find_route`].
 584         ///
 585         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
 586         /// [`find_route`]: crate::routing::router::find_route
 587         pub(crate) fn for_keysend() -> InvoiceFeatures {
 588                 let mut res = InvoiceFeatures::empty();
 589                 res.set_variable_length_onion_optional();
 590                 res
 591         }
 592 }
 593
 594 impl ChannelTypeFeatures {
 595         /// Constructs the implicit channel type based on the common supported types between us and our
 596         /// counterparty
 597         pub(crate) fn from_counterparty_init(counterparty_init: &InitFeatures) -> Self {
 598                 let mut ret = counterparty_init.to_context_internal();
 599                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
 600                 // optional bits and then AND out the optional ones.
 601                 for byte in ret.flags.iter_mut() {
 602                         *byte |= (*byte & 0b10_10_10_10) >> 1;
 603                         *byte &= 0b01_01_01_01;
 604                 }
 605                 ret
 606         }
 607
 608         /// Constructs a ChannelTypeFeatures with only static_remotekey set
 609         pub(crate) fn only_static_remote_key() -> Self {
 610                 let mut ret = Self::empty();
 611                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
 612                 ret
 613         }
 614 }
 615
 616 impl ToBase32 for InvoiceFeatures {
 617         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
 618                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
 619                 // minus one before dividing
 620                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
 621                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
 622                 for (byte_idx, byte) in self.flags.iter().enumerate() {
 623                         let bit_pos_from_left_0_indexed = byte_idx * 8;
 624                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
 625                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
 626                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
 627                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
 628                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
 629                         if new_u5_idx > 0 {
 630                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
 631                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
 632                         }
 633                         if new_u5_idx > 1 {
 634                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
 635                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
 636                         }
 637                 }
 638                 // Trim the highest feature bits.
 639                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
 640                         res_u5s.remove(0);
 641                 }
 642                 writer.write(&res_u5s)
 643         }
 644 }
 645
 646 impl Base32Len for InvoiceFeatures {
 647         fn base32_len(&self) -> usize {
 648                 self.to_base32().len()
 649         }
 650 }
 651
 652 impl FromBase32 for InvoiceFeatures {
 653         type Err = bech32::Error;
 654
 655         fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
 656                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
 657                 // minus one before dividing
 658                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
 659                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
 660                 for (u5_idx, chunk) in field_data.iter().enumerate() {
 661                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
 662                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
 663                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
 664                         let chunk_u16 = chunk.to_u8() as u16;
 665                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
 666                         if new_byte_idx != length_bytes - 1 {
 667                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
 668                         }
 669                 }
 670                 // Trim the highest feature bits.
 671                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
 672                         res_bytes.pop();
 673                 }
 674                 Ok(InvoiceFeatures::from_le_bytes(res_bytes))
 675         }
 676 }
 677
 678 impl<T: sealed::Context> Features<T> {
 679         /// Create a blank Features with no features set
 680         pub fn empty() -> Self {
 681                 Features {
 682                         flags: Vec::new(),
 683                         mark: PhantomData,
 684                 }
 685         }
 686
 687         /// Creates a Features with the bits set which are known by the implementation
 688         pub fn known() -> Self {
 689                 Self {
 690                         flags: T::KNOWN_FEATURE_FLAGS.to_vec(),
 691                         mark: PhantomData,
 692                 }
 693         }
 694
 695         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
 696         /// included in the result.
 697         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
 698                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
 699                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
 700                 let mut flags = Vec::new();
 701                 for (i, byte) in self.flags.iter().enumerate() {
 702                         if i < from_byte_count && i < to_byte_count {
 703                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
 704                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
 705                                 flags.push(byte & from_known_features & to_known_features);
 706                         }
 707                 }
 708                 Features::<C> { flags, mark: PhantomData, }
 709         }
 710
 711         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
 712         /// most on-the-wire encodings.
 713         /// (C-not exported) as we don't support export across multiple T
 714         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 715                 Features {
 716                         flags,
 717                         mark: PhantomData,
 718                 }
 719         }
 720
 721         #[cfg(test)]
 722         /// Gets the underlying flags set, in LE.
 723         pub fn le_flags(&self) -> &Vec<u8> {
 724                 &self.flags
 725         }
 726
 727         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 728                 for f in self.flags.iter().rev() { // Swap back to big-endian
 729                         f.write(w)?;
 730                 }
 731                 Ok(())
 732         }
 733
 734         fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
 735                 flags.reverse(); // Swap to little-endian
 736                 Self {
 737                         flags,
 738                         mark: PhantomData,
 739                 }
 740         }
 741
 742         pub(crate) fn supports_any_optional_bits(&self) -> bool {
 743                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
 744         }
 745
 746         /// Returns true if this `Features` object contains unknown feature flags which are set as
 747         /// "required".
 748         pub fn requires_unknown_bits(&self) -> bool {
 749                 // Bitwise AND-ing with all even bits set except for known features will select required
 750                 // unknown features.
 751                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 752                 self.flags.iter().enumerate().any(|(i, &byte)| {
 753                         let required_features = 0b01_01_01_01;
 754                         let unknown_features = if i < byte_count {
 755                                 !T::KNOWN_FEATURE_MASK[i]
 756                         } else {
 757                                 0b11_11_11_11
 758                         };
 759                         (byte & (required_features & unknown_features)) != 0
 760                 })
 761         }
 762
 763         pub(crate) fn supports_unknown_bits(&self) -> bool {
 764                 // Bitwise AND-ing with all even and odd bits set except for known features will select
 765                 // both required and optional unknown features.
 766                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 767                 self.flags.iter().enumerate().any(|(i, &byte)| {
 768                         let unknown_features = if i < byte_count {
 769                                 !T::KNOWN_FEATURE_MASK[i]
 770                         } else {
 771                                 0b11_11_11_11
 772                         };
 773                         (byte & unknown_features) != 0
 774                 })
 775         }
 776 }
 777
 778 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 779         #[cfg(test)]
 780         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
 781                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
 782                 self
 783         }
 784 }
 785
 786
 787 impl<T: sealed::GossipQueries> Features<T> {
 788         pub(crate) fn clear_gossip_queries(mut self) -> Self {
 789                 <T as sealed::GossipQueries>::clear_bits(&mut self.flags);
 790                 self
 791         }
 792 }
 793
 794 impl<T: sealed::InitialRoutingSync> Features<T> {
 795         // Note that initial_routing_sync is ignored if gossip_queries is set.
 796         pub(crate) fn clear_initial_routing_sync(mut self) -> Self {
 797                 <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags);
 798                 self
 799         }
 800 }
 801
 802 impl<T: sealed::ShutdownAnySegwit> Features<T> {
 803         #[cfg(test)]
 804         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
 805                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
 806                 self
 807         }
 808 }
 809
 810 impl<T: sealed::Wumbo> Features<T> {
 811         #[cfg(test)]
 812         pub(crate) fn clear_wumbo(mut self) -> Self {
 813                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
 814                 self
 815         }
 816 }
 817
 818 macro_rules! impl_feature_len_prefixed_write {
 819         ($features: ident) => {
 820                 impl Writeable for $features {
 821                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 822                                 (self.flags.len() as u16).write(w)?;
 823                                 self.write_be(w)
 824                         }
 825                 }
 826                 impl Readable for $features {
 827                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 828                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
 829                         }
 830                 }
 831         }
 832 }
 833 impl_feature_len_prefixed_write!(InitFeatures);
 834 impl_feature_len_prefixed_write!(ChannelFeatures);
 835 impl_feature_len_prefixed_write!(NodeFeatures);
 836 impl_feature_len_prefixed_write!(InvoiceFeatures);
 837
 838 // Because ChannelTypeFeatures only appears inside of TLVs, it doesn't have a length prefix when
 839 // serialized. Thus, we can't use `impl_feature_len_prefixed_write`, above, and have to write our
 840 // own serialization.
 841 impl Writeable for ChannelTypeFeatures {
 842         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 843                 self.write_be(w)
 844         }
 845 }
 846 impl Readable for ChannelTypeFeatures {
 847         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 848                 let v = io_extras::read_to_end(r)?;
 849                 Ok(Self::from_be_bytes(v))
 850         }
 851 }
 852
 853 #[cfg(test)]
 854 mod tests {
 855         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
 856         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
 857
 858         #[test]
 859         fn sanity_test_known_features() {
 860                 assert!(!ChannelFeatures::known().requires_unknown_bits());
 861                 assert!(!ChannelFeatures::known().supports_unknown_bits());
 862                 assert!(!InitFeatures::known().requires_unknown_bits());
 863                 assert!(!InitFeatures::known().supports_unknown_bits());
 864                 assert!(!NodeFeatures::known().requires_unknown_bits());
 865                 assert!(!NodeFeatures::known().supports_unknown_bits());
 866
 867                 assert!(InitFeatures::known().supports_upfront_shutdown_script());
 868                 assert!(NodeFeatures::known().supports_upfront_shutdown_script());
 869                 assert!(!InitFeatures::known().requires_upfront_shutdown_script());
 870                 assert!(!NodeFeatures::known().requires_upfront_shutdown_script());
 871
 872                 assert!(InitFeatures::known().supports_gossip_queries());
 873                 assert!(NodeFeatures::known().supports_gossip_queries());
 874                 assert!(!InitFeatures::known().requires_gossip_queries());
 875                 assert!(!NodeFeatures::known().requires_gossip_queries());
 876
 877                 assert!(InitFeatures::known().supports_data_loss_protect());
 878                 assert!(NodeFeatures::known().supports_data_loss_protect());
 879                 assert!(!InitFeatures::known().requires_data_loss_protect());
 880                 assert!(!NodeFeatures::known().requires_data_loss_protect());
 881
 882                 assert!(InitFeatures::known().supports_variable_length_onion());
 883                 assert!(NodeFeatures::known().supports_variable_length_onion());
 884                 assert!(InvoiceFeatures::known().supports_variable_length_onion());
 885                 assert!(InitFeatures::known().requires_variable_length_onion());
 886                 assert!(NodeFeatures::known().requires_variable_length_onion());
 887                 assert!(InvoiceFeatures::known().requires_variable_length_onion());
 888
 889                 assert!(InitFeatures::known().supports_static_remote_key());
 890                 assert!(NodeFeatures::known().supports_static_remote_key());
 891                 assert!(InitFeatures::known().requires_static_remote_key());
 892                 assert!(NodeFeatures::known().requires_static_remote_key());
 893
 894                 assert!(InitFeatures::known().supports_payment_secret());
 895                 assert!(NodeFeatures::known().supports_payment_secret());
 896                 assert!(InvoiceFeatures::known().supports_payment_secret());
 897                 assert!(InitFeatures::known().requires_payment_secret());
 898                 assert!(NodeFeatures::known().requires_payment_secret());
 899                 assert!(InvoiceFeatures::known().requires_payment_secret());
 900
 901                 assert!(InitFeatures::known().supports_basic_mpp());
 902                 assert!(NodeFeatures::known().supports_basic_mpp());
 903                 assert!(InvoiceFeatures::known().supports_basic_mpp());
 904                 assert!(!InitFeatures::known().requires_basic_mpp());
 905                 assert!(!NodeFeatures::known().requires_basic_mpp());
 906                 assert!(!InvoiceFeatures::known().requires_basic_mpp());
 907
 908                 assert!(InitFeatures::known().supports_channel_type());
 909                 assert!(NodeFeatures::known().supports_channel_type());
 910                 assert!(!InitFeatures::known().requires_channel_type());
 911                 assert!(!NodeFeatures::known().requires_channel_type());
 912
 913                 assert!(InitFeatures::known().supports_shutdown_anysegwit());
 914                 assert!(NodeFeatures::known().supports_shutdown_anysegwit());
 915
 916                 assert!(InitFeatures::known().supports_scid_privacy());
 917                 assert!(NodeFeatures::known().supports_scid_privacy());
 918                 assert!(ChannelTypeFeatures::known().supports_scid_privacy());
 919                 assert!(!InitFeatures::known().requires_scid_privacy());
 920                 assert!(!NodeFeatures::known().requires_scid_privacy());
 921                 assert!(ChannelTypeFeatures::known().requires_scid_privacy());
 922
 923                 assert!(InitFeatures::known().supports_wumbo());
 924                 assert!(NodeFeatures::known().supports_wumbo());
 925                 assert!(!InitFeatures::known().requires_wumbo());
 926                 assert!(!NodeFeatures::known().requires_wumbo());
 927
 928                 assert!(InitFeatures::known().supports_onion_messages());
 929                 assert!(NodeFeatures::known().supports_onion_messages());
 930                 assert!(!InitFeatures::known().requires_onion_messages());
 931                 assert!(!NodeFeatures::known().requires_onion_messages());
 932
 933                 assert!(InitFeatures::known().supports_zero_conf());
 934                 assert!(!InitFeatures::known().requires_zero_conf());
 935                 assert!(NodeFeatures::known().supports_zero_conf());
 936                 assert!(!NodeFeatures::known().requires_zero_conf());
 937                 assert!(ChannelTypeFeatures::known().supports_zero_conf());
 938                 assert!(ChannelTypeFeatures::known().requires_zero_conf());
 939
 940                 let mut init_features = InitFeatures::known();
 941                 assert!(init_features.initial_routing_sync());
 942                 init_features = init_features.clear_initial_routing_sync();
 943                 assert!(!init_features.initial_routing_sync());
 944         }
 945
 946         #[test]
 947         fn sanity_test_unknown_bits() {
 948                 let features = ChannelFeatures::empty();
 949                 assert!(!features.requires_unknown_bits());
 950                 assert!(!features.supports_unknown_bits());
 951
 952                 let mut features = ChannelFeatures::empty();
 953                 features.set_unknown_feature_required();
 954                 assert!(features.requires_unknown_bits());
 955                 assert!(features.supports_unknown_bits());
 956
 957                 let mut features = ChannelFeatures::empty();
 958                 features.set_unknown_feature_optional();
 959                 assert!(!features.requires_unknown_bits());
 960                 assert!(features.supports_unknown_bits());
 961         }
 962
 963         #[test]
 964         fn convert_to_context_with_relevant_flags() {
 965                 let init_features = InitFeatures::known().clear_upfront_shutdown_script().clear_gossip_queries();
 966                 assert!(init_features.initial_routing_sync());
 967                 assert!(!init_features.supports_upfront_shutdown_script());
 968                 assert!(!init_features.supports_gossip_queries());
 969
 970                 let node_features: NodeFeatures = init_features.to_context();
 971                 {
 972                         // Check that the flags are as expected:
 973                         // - option_data_loss_protect
 974                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
 975                         // - basic_mpp | wumbo
 976                         // - opt_shutdown_anysegwit
 977                         // - onion_messages
 978                         // - option_channel_type | option_scid_alias
 979                         // - option_zeroconf
 980                         assert_eq!(node_features.flags.len(), 7);
 981                         assert_eq!(node_features.flags[0], 0b00000010);
 982                         assert_eq!(node_features.flags[1], 0b01010001);
 983                         assert_eq!(node_features.flags[2], 0b00001010);
 984                         assert_eq!(node_features.flags[3], 0b00001000);
 985                         assert_eq!(node_features.flags[4], 0b10000000);
 986                         assert_eq!(node_features.flags[5], 0b10100000);
 987                         assert_eq!(node_features.flags[6], 0b00001000);
 988                 }
 989
 990                 // Check that cleared flags are kept blank when converting back:
 991                 // - initial_routing_sync was not applicable to NodeContext
 992                 // - upfront_shutdown_script was cleared before converting
 993                 // - gossip_queries was cleared before converting
 994                 let features: InitFeatures = node_features.to_context_internal();
 995                 assert!(!features.initial_routing_sync());
 996                 assert!(!features.supports_upfront_shutdown_script());
 997                 assert!(!init_features.supports_gossip_queries());
 998         }
 999
1000         #[test]
1001         fn convert_to_context_with_unknown_flags() {
1002                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1003                 assert!(InvoiceFeatures::known().flags.len() < NodeFeatures::known().flags.len());
1004                 let mut invoice_features = InvoiceFeatures::known();
1005                 invoice_features.set_unknown_feature_optional();
1006                 assert!(invoice_features.supports_unknown_bits());
1007                 let node_features: NodeFeatures = invoice_features.to_context();
1008                 assert!(!node_features.supports_unknown_bits());
1009         }
1010
1011         #[test]
1012         fn set_feature_bits() {
1013                 let mut features = InvoiceFeatures::empty();
1014                 features.set_basic_mpp_optional();
1015                 features.set_payment_secret_required();
1016                 assert!(features.supports_basic_mpp());
1017                 assert!(!features.requires_basic_mpp());
1018                 assert!(features.requires_payment_secret());
1019                 assert!(features.supports_payment_secret());
1020         }
1021
1022         #[test]
1023         fn invoice_features_encoding() {
1024                 let features_as_u5s = vec![
1025                         u5::try_from_u8(6).unwrap(),
1026                         u5::try_from_u8(10).unwrap(),
1027                         u5::try_from_u8(25).unwrap(),
1028                         u5::try_from_u8(1).unwrap(),
1029                         u5::try_from_u8(10).unwrap(),
1030                         u5::try_from_u8(0).unwrap(),
1031                         u5::try_from_u8(20).unwrap(),
1032                         u5::try_from_u8(2).unwrap(),
1033                         u5::try_from_u8(0).unwrap(),
1034                         u5::try_from_u8(6).unwrap(),
1035                         u5::try_from_u8(0).unwrap(),
1036                         u5::try_from_u8(16).unwrap(),
1037                         u5::try_from_u8(1).unwrap(),
1038                 ];
1039                 let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1040
1041                 // Test length calculation.
1042                 assert_eq!(features.base32_len(), 13);
1043
1044                 // Test serialization.
1045                 let features_serialized = features.to_base32();
1046                 assert_eq!(features_as_u5s, features_serialized);
1047
1048                 // Test deserialization.
1049                 let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1050                 assert_eq!(features, features_deserialized);
1051         }
1052
1053         #[test]
1054         fn test_channel_type_mapping() {
1055                 // If we map an InvoiceFeatures with StaticRemoteKey optional, it should map into a
1056                 // required-StaticRemoteKey ChannelTypeFeatures.
1057                 let mut init_features = InitFeatures::empty();
1058                 init_features.set_static_remote_key_optional();
1059                 let converted_features = ChannelTypeFeatures::from_counterparty_init(&init_features);
1060                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1061                 assert!(!converted_features.supports_any_optional_bits());
1062                 assert!(converted_features.requires_static_remote_key());
1063         }
1064 }