_ 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                         .clear_onion_messages()
 563         }
 564 }
 565
 566 impl NodeFeatures {
 567         /// Returns the set of known node features that are related to channels.
 568         pub fn known_channel_features() -> NodeFeatures {
 569                 Self::known()
 570                         .clear_gossip_queries()
 571                         .clear_onion_messages()
 572         }
 573 }
 574
 575 impl InvoiceFeatures {
 576         /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
 577         /// context `C` are included in the result.
 578         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 579                 self.to_context_internal()
 580         }
 581
 582         /// Getting a route for a keysend payment to a private node requires providing the payee's
 583         /// features (since they were not announced in a node announcement). However, keysend payments
 584         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
 585         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
 586         /// `InvoiceFeatures` for [`find_route`].
 587         ///
 588         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
 589         /// [`find_route`]: crate::routing::router::find_route
 590         pub(crate) fn for_keysend() -> InvoiceFeatures {
 591                 let mut res = InvoiceFeatures::empty();
 592                 res.set_variable_length_onion_optional();
 593                 res
 594         }
 595 }
 596
 597 impl ChannelTypeFeatures {
 598         /// Constructs the implicit channel type based on the common supported types between us and our
 599         /// counterparty
 600         pub(crate) fn from_counterparty_init(counterparty_init: &InitFeatures) -> Self {
 601                 let mut ret = counterparty_init.to_context_internal();
 602                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
 603                 // optional bits and then AND out the optional ones.
 604                 for byte in ret.flags.iter_mut() {
 605                         *byte |= (*byte & 0b10_10_10_10) >> 1;
 606                         *byte &= 0b01_01_01_01;
 607                 }
 608                 ret
 609         }
 610
 611         /// Constructs a ChannelTypeFeatures with only static_remotekey set
 612         pub(crate) fn only_static_remote_key() -> Self {
 613                 let mut ret = Self::empty();
 614                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
 615                 ret
 616         }
 617 }
 618
 619 impl ToBase32 for InvoiceFeatures {
 620         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
 621                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
 622                 // minus one before dividing
 623                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
 624                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
 625                 for (byte_idx, byte) in self.flags.iter().enumerate() {
 626                         let bit_pos_from_left_0_indexed = byte_idx * 8;
 627                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
 628                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
 629                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
 630                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
 631                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
 632                         if new_u5_idx > 0 {
 633                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
 634                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
 635                         }
 636                         if new_u5_idx > 1 {
 637                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
 638                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
 639                         }
 640                 }
 641                 // Trim the highest feature bits.
 642                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
 643                         res_u5s.remove(0);
 644                 }
 645                 writer.write(&res_u5s)
 646         }
 647 }
 648
 649 impl Base32Len for InvoiceFeatures {
 650         fn base32_len(&self) -> usize {
 651                 self.to_base32().len()
 652         }
 653 }
 654
 655 impl FromBase32 for InvoiceFeatures {
 656         type Err = bech32::Error;
 657
 658         fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
 659                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
 660                 // minus one before dividing
 661                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
 662                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
 663                 for (u5_idx, chunk) in field_data.iter().enumerate() {
 664                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
 665                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
 666                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
 667                         let chunk_u16 = chunk.to_u8() as u16;
 668                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
 669                         if new_byte_idx != length_bytes - 1 {
 670                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
 671                         }
 672                 }
 673                 // Trim the highest feature bits.
 674                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
 675                         res_bytes.pop();
 676                 }
 677                 Ok(InvoiceFeatures::from_le_bytes(res_bytes))
 678         }
 679 }
 680
 681 impl<T: sealed::Context> Features<T> {
 682         /// Create a blank Features with no features set
 683         pub fn empty() -> Self {
 684                 Features {
 685                         flags: Vec::new(),
 686                         mark: PhantomData,
 687                 }
 688         }
 689
 690         /// Creates a Features with the bits set which are known by the implementation
 691         pub fn known() -> Self {
 692                 Self {
 693                         flags: T::KNOWN_FEATURE_FLAGS.to_vec(),
 694                         mark: PhantomData,
 695                 }
 696         }
 697
 698         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
 699         /// included in the result.
 700         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
 701                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
 702                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
 703                 let mut flags = Vec::new();
 704                 for (i, byte) in self.flags.iter().enumerate() {
 705                         if i < from_byte_count && i < to_byte_count {
 706                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
 707                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
 708                                 flags.push(byte & from_known_features & to_known_features);
 709                         }
 710                 }
 711                 Features::<C> { flags, mark: PhantomData, }
 712         }
 713
 714         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
 715         /// most on-the-wire encodings.
 716         /// (C-not exported) as we don't support export across multiple T
 717         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 718                 Features {
 719                         flags,
 720                         mark: PhantomData,
 721                 }
 722         }
 723
 724         #[cfg(test)]
 725         /// Gets the underlying flags set, in LE.
 726         pub fn le_flags(&self) -> &Vec<u8> {
 727                 &self.flags
 728         }
 729
 730         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 731                 for f in self.flags.iter().rev() { // Swap back to big-endian
 732                         f.write(w)?;
 733                 }
 734                 Ok(())
 735         }
 736
 737         fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
 738                 flags.reverse(); // Swap to little-endian
 739                 Self {
 740                         flags,
 741                         mark: PhantomData,
 742                 }
 743         }
 744
 745         pub(crate) fn supports_any_optional_bits(&self) -> bool {
 746                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
 747         }
 748
 749         /// Returns true if this `Features` object contains unknown feature flags which are set as
 750         /// "required".
 751         pub fn requires_unknown_bits(&self) -> bool {
 752                 // Bitwise AND-ing with all even bits set except for known features will select required
 753                 // unknown features.
 754                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 755                 self.flags.iter().enumerate().any(|(i, &byte)| {
 756                         let required_features = 0b01_01_01_01;
 757                         let unknown_features = if i < byte_count {
 758                                 !T::KNOWN_FEATURE_MASK[i]
 759                         } else {
 760                                 0b11_11_11_11
 761                         };
 762                         (byte & (required_features & unknown_features)) != 0
 763                 })
 764         }
 765
 766         pub(crate) fn supports_unknown_bits(&self) -> bool {
 767                 // Bitwise AND-ing with all even and odd bits set except for known features will select
 768                 // both required and optional unknown features.
 769                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 770                 self.flags.iter().enumerate().any(|(i, &byte)| {
 771                         let unknown_features = if i < byte_count {
 772                                 !T::KNOWN_FEATURE_MASK[i]
 773                         } else {
 774                                 0b11_11_11_11
 775                         };
 776                         (byte & unknown_features) != 0
 777                 })
 778         }
 779 }
 780
 781 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 782         #[cfg(test)]
 783         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
 784                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
 785                 self
 786         }
 787 }
 788
 789
 790 impl<T: sealed::GossipQueries> Features<T> {
 791         pub(crate) fn clear_gossip_queries(mut self) -> Self {
 792                 <T as sealed::GossipQueries>::clear_bits(&mut self.flags);
 793                 self
 794         }
 795 }
 796
 797 impl<T: sealed::InitialRoutingSync> Features<T> {
 798         // Note that initial_routing_sync is ignored if gossip_queries is set.
 799         pub(crate) fn clear_initial_routing_sync(mut self) -> Self {
 800                 <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags);
 801                 self
 802         }
 803 }
 804
 805 impl<T: sealed::OnionMessages> Features<T> {
 806         pub(crate) fn clear_onion_messages(mut self) -> Self {
 807                 <T as sealed::OnionMessages>::clear_bits(&mut self.flags);
 808                 self
 809         }
 810 }
 811
 812 impl<T: sealed::ShutdownAnySegwit> Features<T> {
 813         #[cfg(test)]
 814         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
 815                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
 816                 self
 817         }
 818 }
 819
 820 impl<T: sealed::Wumbo> Features<T> {
 821         #[cfg(test)]
 822         pub(crate) fn clear_wumbo(mut self) -> Self {
 823                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
 824                 self
 825         }
 826 }
 827
 828 macro_rules! impl_feature_len_prefixed_write {
 829         ($features: ident) => {
 830                 impl Writeable for $features {
 831                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 832                                 (self.flags.len() as u16).write(w)?;
 833                                 self.write_be(w)
 834                         }
 835                 }
 836                 impl Readable for $features {
 837                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 838                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
 839                         }
 840                 }
 841         }
 842 }
 843 impl_feature_len_prefixed_write!(InitFeatures);
 844 impl_feature_len_prefixed_write!(ChannelFeatures);
 845 impl_feature_len_prefixed_write!(NodeFeatures);
 846 impl_feature_len_prefixed_write!(InvoiceFeatures);
 847
 848 // Because ChannelTypeFeatures only appears inside of TLVs, it doesn't have a length prefix when
 849 // serialized. Thus, we can't use `impl_feature_len_prefixed_write`, above, and have to write our
 850 // own serialization.
 851 impl Writeable for ChannelTypeFeatures {
 852         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 853                 self.write_be(w)
 854         }
 855 }
 856 impl Readable for ChannelTypeFeatures {
 857         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 858                 let v = io_extras::read_to_end(r)?;
 859                 Ok(Self::from_be_bytes(v))
 860         }
 861 }
 862
 863 #[cfg(test)]
 864 mod tests {
 865         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
 866         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
 867
 868         #[test]
 869         fn sanity_test_known_features() {
 870                 assert!(!ChannelFeatures::known().requires_unknown_bits());
 871                 assert!(!ChannelFeatures::known().supports_unknown_bits());
 872                 assert!(!InitFeatures::known().requires_unknown_bits());
 873                 assert!(!InitFeatures::known().supports_unknown_bits());
 874                 assert!(!NodeFeatures::known().requires_unknown_bits());
 875                 assert!(!NodeFeatures::known().supports_unknown_bits());
 876
 877                 assert!(InitFeatures::known().supports_upfront_shutdown_script());
 878                 assert!(NodeFeatures::known().supports_upfront_shutdown_script());
 879                 assert!(!InitFeatures::known().requires_upfront_shutdown_script());
 880                 assert!(!NodeFeatures::known().requires_upfront_shutdown_script());
 881
 882                 assert!(InitFeatures::known().supports_gossip_queries());
 883                 assert!(NodeFeatures::known().supports_gossip_queries());
 884                 assert!(!InitFeatures::known().requires_gossip_queries());
 885                 assert!(!NodeFeatures::known().requires_gossip_queries());
 886
 887                 assert!(InitFeatures::known().supports_data_loss_protect());
 888                 assert!(NodeFeatures::known().supports_data_loss_protect());
 889                 assert!(!InitFeatures::known().requires_data_loss_protect());
 890                 assert!(!NodeFeatures::known().requires_data_loss_protect());
 891
 892                 assert!(InitFeatures::known().supports_variable_length_onion());
 893                 assert!(NodeFeatures::known().supports_variable_length_onion());
 894                 assert!(InvoiceFeatures::known().supports_variable_length_onion());
 895                 assert!(InitFeatures::known().requires_variable_length_onion());
 896                 assert!(NodeFeatures::known().requires_variable_length_onion());
 897                 assert!(InvoiceFeatures::known().requires_variable_length_onion());
 898
 899                 assert!(InitFeatures::known().supports_static_remote_key());
 900                 assert!(NodeFeatures::known().supports_static_remote_key());
 901                 assert!(InitFeatures::known().requires_static_remote_key());
 902                 assert!(NodeFeatures::known().requires_static_remote_key());
 903
 904                 assert!(InitFeatures::known().supports_payment_secret());
 905                 assert!(NodeFeatures::known().supports_payment_secret());
 906                 assert!(InvoiceFeatures::known().supports_payment_secret());
 907                 assert!(InitFeatures::known().requires_payment_secret());
 908                 assert!(NodeFeatures::known().requires_payment_secret());
 909                 assert!(InvoiceFeatures::known().requires_payment_secret());
 910
 911                 assert!(InitFeatures::known().supports_basic_mpp());
 912                 assert!(NodeFeatures::known().supports_basic_mpp());
 913                 assert!(InvoiceFeatures::known().supports_basic_mpp());
 914                 assert!(!InitFeatures::known().requires_basic_mpp());
 915                 assert!(!NodeFeatures::known().requires_basic_mpp());
 916                 assert!(!InvoiceFeatures::known().requires_basic_mpp());
 917
 918                 assert!(InitFeatures::known().supports_channel_type());
 919                 assert!(NodeFeatures::known().supports_channel_type());
 920                 assert!(!InitFeatures::known().requires_channel_type());
 921                 assert!(!NodeFeatures::known().requires_channel_type());
 922
 923                 assert!(InitFeatures::known().supports_shutdown_anysegwit());
 924                 assert!(NodeFeatures::known().supports_shutdown_anysegwit());
 925
 926                 assert!(InitFeatures::known().supports_scid_privacy());
 927                 assert!(NodeFeatures::known().supports_scid_privacy());
 928                 assert!(ChannelTypeFeatures::known().supports_scid_privacy());
 929                 assert!(!InitFeatures::known().requires_scid_privacy());
 930                 assert!(!NodeFeatures::known().requires_scid_privacy());
 931                 assert!(ChannelTypeFeatures::known().requires_scid_privacy());
 932
 933                 assert!(InitFeatures::known().supports_wumbo());
 934                 assert!(NodeFeatures::known().supports_wumbo());
 935                 assert!(!InitFeatures::known().requires_wumbo());
 936                 assert!(!NodeFeatures::known().requires_wumbo());
 937
 938                 assert!(InitFeatures::known().supports_onion_messages());
 939                 assert!(NodeFeatures::known().supports_onion_messages());
 940                 assert!(!InitFeatures::known().requires_onion_messages());
 941                 assert!(!NodeFeatures::known().requires_onion_messages());
 942
 943                 assert!(InitFeatures::known().supports_zero_conf());
 944                 assert!(!InitFeatures::known().requires_zero_conf());
 945                 assert!(NodeFeatures::known().supports_zero_conf());
 946                 assert!(!NodeFeatures::known().requires_zero_conf());
 947                 assert!(ChannelTypeFeatures::known().supports_zero_conf());
 948                 assert!(ChannelTypeFeatures::known().requires_zero_conf());
 949
 950                 let mut init_features = InitFeatures::known();
 951                 assert!(init_features.initial_routing_sync());
 952                 init_features = init_features.clear_initial_routing_sync();
 953                 assert!(!init_features.initial_routing_sync());
 954         }
 955
 956         #[test]
 957         fn sanity_test_unknown_bits() {
 958                 let features = ChannelFeatures::empty();
 959                 assert!(!features.requires_unknown_bits());
 960                 assert!(!features.supports_unknown_bits());
 961
 962                 let mut features = ChannelFeatures::empty();
 963                 features.set_unknown_feature_required();
 964                 assert!(features.requires_unknown_bits());
 965                 assert!(features.supports_unknown_bits());
 966
 967                 let mut features = ChannelFeatures::empty();
 968                 features.set_unknown_feature_optional();
 969                 assert!(!features.requires_unknown_bits());
 970                 assert!(features.supports_unknown_bits());
 971         }
 972
 973         #[test]
 974         fn convert_to_context_with_relevant_flags() {
 975                 let init_features = InitFeatures::known().clear_upfront_shutdown_script().clear_gossip_queries();
 976                 assert!(init_features.initial_routing_sync());
 977                 assert!(!init_features.supports_upfront_shutdown_script());
 978                 assert!(!init_features.supports_gossip_queries());
 979
 980                 let node_features: NodeFeatures = init_features.to_context();
 981                 {
 982                         // Check that the flags are as expected:
 983                         // - option_data_loss_protect
 984                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
 985                         // - basic_mpp | wumbo
 986                         // - opt_shutdown_anysegwit
 987                         // - onion_messages
 988                         // - option_channel_type | option_scid_alias
 989                         // - option_zeroconf
 990                         assert_eq!(node_features.flags.len(), 7);
 991                         assert_eq!(node_features.flags[0], 0b00000010);
 992                         assert_eq!(node_features.flags[1], 0b01010001);
 993                         assert_eq!(node_features.flags[2], 0b00001010);
 994                         assert_eq!(node_features.flags[3], 0b00001000);
 995                         assert_eq!(node_features.flags[4], 0b10000000);
 996                         assert_eq!(node_features.flags[5], 0b10100000);
 997                         assert_eq!(node_features.flags[6], 0b00001000);
 998                 }
 999
1000                 // Check that cleared flags are kept blank when converting back:
1001                 // - initial_routing_sync was not applicable to NodeContext
1002                 // - upfront_shutdown_script was cleared before converting
1003                 // - gossip_queries was cleared before converting
1004                 let features: InitFeatures = node_features.to_context_internal();
1005                 assert!(!features.initial_routing_sync());
1006                 assert!(!features.supports_upfront_shutdown_script());
1007                 assert!(!init_features.supports_gossip_queries());
1008         }
1009
1010         #[test]
1011         fn convert_to_context_with_unknown_flags() {
1012                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1013                 assert!(InvoiceFeatures::known().flags.len() < NodeFeatures::known().flags.len());
1014                 let mut invoice_features = InvoiceFeatures::known();
1015                 invoice_features.set_unknown_feature_optional();
1016                 assert!(invoice_features.supports_unknown_bits());
1017                 let node_features: NodeFeatures = invoice_features.to_context();
1018                 assert!(!node_features.supports_unknown_bits());
1019         }
1020
1021         #[test]
1022         fn set_feature_bits() {
1023                 let mut features = InvoiceFeatures::empty();
1024                 features.set_basic_mpp_optional();
1025                 features.set_payment_secret_required();
1026                 assert!(features.supports_basic_mpp());
1027                 assert!(!features.requires_basic_mpp());
1028                 assert!(features.requires_payment_secret());
1029                 assert!(features.supports_payment_secret());
1030         }
1031
1032         #[test]
1033         fn invoice_features_encoding() {
1034                 let features_as_u5s = vec![
1035                         u5::try_from_u8(6).unwrap(),
1036                         u5::try_from_u8(10).unwrap(),
1037                         u5::try_from_u8(25).unwrap(),
1038                         u5::try_from_u8(1).unwrap(),
1039                         u5::try_from_u8(10).unwrap(),
1040                         u5::try_from_u8(0).unwrap(),
1041                         u5::try_from_u8(20).unwrap(),
1042                         u5::try_from_u8(2).unwrap(),
1043                         u5::try_from_u8(0).unwrap(),
1044                         u5::try_from_u8(6).unwrap(),
1045                         u5::try_from_u8(0).unwrap(),
1046                         u5::try_from_u8(16).unwrap(),
1047                         u5::try_from_u8(1).unwrap(),
1048                 ];
1049                 let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1050
1051                 // Test length calculation.
1052                 assert_eq!(features.base32_len(), 13);
1053
1054                 // Test serialization.
1055                 let features_serialized = features.to_base32();
1056                 assert_eq!(features_as_u5s, features_serialized);
1057
1058                 // Test deserialization.
1059                 let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1060                 assert_eq!(features, features_deserialized);
1061         }
1062
1063         #[test]
1064         fn test_channel_type_mapping() {
1065                 // If we map an InvoiceFeatures with StaticRemoteKey optional, it should map into a
1066                 // required-StaticRemoteKey ChannelTypeFeatures.
1067                 let mut init_features = InitFeatures::empty();
1068                 init_features.set_static_remote_key_optional();
1069                 let converted_features = ChannelTypeFeatures::from_counterparty_init(&init_features);
1070                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1071                 assert!(!converted_features.supports_any_optional_bits());
1072                 assert!(converted_features.requires_static_remote_key());
1073         }
1074 }