_ Git - rust-lightning/blob - lightning/src/ln/features.rs

   1 //! Feature flag definitions for the Lightning protocol according to [BOLT #9].
   2 //!
   3 //! Lightning nodes advertise a supported set of operation through feature flags. Features are
   4 //! applicable for a specific context as indicated in some [messages]. [`Features`] encapsulates
   5 //! behavior for specifying and checking feature flags for a particular context. Each feature is
   6 //! defined internally by a trait specifying the corresponding flags (i.e., even and odd bits). A
   7 //! [`Context`] is used to parameterize [`Features`] and defines which features it can support.
   8 //!
   9 //! Whether a feature is considered "known" or "unknown" is relative to the implementation, whereas
  10 //! the term "supports" is used in reference to a particular set of [`Features`]. That is, a node
  11 //! supports a feature if it advertises the feature (as either required or optional) to its peers.
  12 //! And the implementation can interpret a feature if the feature is known to it.
  13 //!
  14 //! [BOLT #9]: https://github.com/lightningnetwork/lightning-rfc/blob/master/09-features.md
  15 //! [messages]: ../msgs/index.html
  16 //! [`Features`]: struct.Features.html
  17 //! [`Context`]: sealed/trait.Context.html
  18
  19 use std::{cmp, fmt};
  20 use std::result::Result;
  21 use std::marker::PhantomData;
  22
  23 use ln::msgs::DecodeError;
  24 use util::ser::{Readable, Writeable, Writer};
  25
  26 mod sealed {
  27         /// The context in which [`Features`] are applicable. Defines which features are required and
  28         /// which are optional for the context.
  29         ///
  30         /// [`Features`]: ../struct.Features.html
  31         pub trait Context {
  32                 /// Features that are known to the implementation, where a required feature is indicated by
  33                 /// its even bit and an optional feature is indicated by its odd bit.
  34                 const KNOWN_FEATURE_FLAGS: &'static [u8];
  35
  36                 /// Bitmask for selecting features that are known to the implementation, regardless of
  37                 /// whether each feature is required or optional.
  38                 const KNOWN_FEATURE_MASK: &'static [u8];
  39         }
  40
  41         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
  42         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
  43         /// feature identifiers.
  44         ///
  45         /// [`Context`]: trait.Context.html
  46         macro_rules! define_context {
  47                 ($context: ident {
  48                         required_features: [$( $( $required_feature: ident )|*, )*],
  49                         optional_features: [$( $( $optional_feature: ident )|*, )*],
  50                 }) => {
  51                         pub struct $context {}
  52
  53                         impl Context for $context {
  54                                 const KNOWN_FEATURE_FLAGS: &'static [u8] = &[
  55                                         // For each byte, use bitwise-OR to compute the applicable flags for known
  56                                         // required features `r_i` and optional features `o_j` for all `i` and `j` such
  57                                         // that the following slice is formed:
  58                                         //
  59                                         // [
  60                                         //  `r_0` | `r_1` | ... | `o_0` | `o_1` | ...,
  61                                         //  ...,
  62                                         // ]
  63                                         $(
  64                                                 0b00_00_00_00 $(|
  65                                                         <Self as $required_feature>::REQUIRED_MASK)*
  66                                                 $(|
  67                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
  68                                         )*
  69                                 ];
  70
  71                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
  72                                         // Similar as above, but set both flags for each feature regardless of whether
  73                                         // the feature is required or optional.
  74                                         $(
  75                                                 0b00_00_00_00 $(|
  76                                                         <Self as $required_feature>::REQUIRED_MASK |
  77                                                         <Self as $required_feature>::OPTIONAL_MASK)*
  78                                                 $(|
  79                                                         <Self as $optional_feature>::REQUIRED_MASK |
  80                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
  81                                         )*
  82                                 ];
  83                         }
  84                 };
  85         }
  86
  87         define_context!(InitContext {
  88                 required_features: [
  89                         // Byte 0
  90                         ,
  91                         // Byte 1
  92                         ,
  93                         // Byte 2
  94                         ,
  95                 ],
  96                 optional_features: [
  97                         // Byte 0
  98                         DataLossProtect | InitialRoutingSync | UpfrontShutdownScript,
  99                         // Byte 1
 100                         VariableLengthOnion | PaymentSecret,
 101                         // Byte 2
 102                         BasicMPP,
 103                 ],
 104         });
 105         define_context!(NodeContext {
 106                 required_features: [
 107                         // Byte 0
 108                         ,
 109                         // Byte 1
 110                         ,
 111                         // Byte 2
 112                         ,
 113                 ],
 114                 optional_features: [
 115                         // Byte 0
 116                         DataLossProtect | UpfrontShutdownScript,
 117                         // Byte 1
 118                         VariableLengthOnion | PaymentSecret,
 119                         // Byte 2
 120                         BasicMPP,
 121                 ],
 122         });
 123         define_context!(ChannelContext {
 124                 required_features: [],
 125                 optional_features: [],
 126         });
 127
 128         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
 129         /// useful for manipulating feature flags.
 130         ///
 131         /// [`Context`]: trait.Context.html
 132         macro_rules! define_feature {
 133                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr) => {
 134                         #[doc = $doc]
 135                         ///
 136                         /// See [BOLT #9] for details.
 137                         ///
 138                         /// [BOLT #9]: https://github.com/lightningnetwork/lightning-rfc/blob/master/09-features.md
 139                         pub trait $feature: Context {
 140                                 /// The bit used to signify that the feature is required.
 141                                 const EVEN_BIT: usize = $odd_bit - 1;
 142
 143                                 /// The bit used to signify that the feature is optional.
 144                                 const ODD_BIT: usize = $odd_bit;
 145
 146                                 /// Assertion that [`EVEN_BIT`] is actually even.
 147                                 ///
 148                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
 149                                 const ASSERT_EVEN_BIT_PARITY: usize;
 150
 151                                 /// Assertion that [`ODD_BIT`] is actually odd.
 152                                 ///
 153                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
 154                                 const ASSERT_ODD_BIT_PARITY: usize;
 155
 156                                 /// The byte where the feature is set.
 157                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
 158
 159                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
 160                                 ///
 161                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 162                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
 163
 164                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
 165                                 ///
 166                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 167                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
 168
 169                                 /// Returns whether the feature is required by the given flags.
 170                                 #[inline]
 171                                 fn requires_feature(flags: &Vec<u8>) -> bool {
 172                                         flags.len() > Self::BYTE_OFFSET &&
 173                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
 174                                 }
 175
 176                                 /// Returns whether the feature is supported by the given flags.
 177                                 #[inline]
 178                                 fn supports_feature(flags: &Vec<u8>) -> bool {
 179                                         flags.len() > Self::BYTE_OFFSET &&
 180                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
 181                                 }
 182
 183                                 /// Sets the feature's required (even) bit in the given flags.
 184                                 #[inline]
 185                                 fn set_required_bit(flags: &mut Vec<u8>) {
 186                                         if flags.len() <= Self::BYTE_OFFSET {
 187                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 188                                         }
 189
 190                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
 191                                 }
 192
 193                                 /// Sets the feature's optional (odd) bit in the given flags.
 194                                 #[inline]
 195                                 fn set_optional_bit(flags: &mut Vec<u8>) {
 196                                         if flags.len() <= Self::BYTE_OFFSET {
 197                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 198                                         }
 199
 200                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
 201                                 }
 202
 203                                 /// Clears the feature's required (even) and optional (odd) bits from the given
 204                                 /// flags.
 205                                 #[inline]
 206                                 fn clear_bits(flags: &mut Vec<u8>) {
 207                                         if flags.len() > Self::BYTE_OFFSET {
 208                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
 209                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 210                                         }
 211
 212                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
 213                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
 214                                         flags.resize(size, 0u8);
 215                                 }
 216                         }
 217
 218                         $(
 219                                 impl $feature for $context {
 220                                         // EVEN_BIT % 2 == 0
 221                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
 222
 223                                         // ODD_BIT % 2 == 1
 224                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
 225                                 }
 226                         )*
 227                 }
 228         }
 229
 230         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
 231                 "Feature flags for `option_data_loss_protect`.");
 232         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
 233         define_feature!(3, InitialRoutingSync, [InitContext],
 234                 "Feature flags for `initial_routing_sync`.");
 235         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
 236                 "Feature flags for `option_upfront_shutdown_script`.");
 237         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext],
 238                 "Feature flags for `var_onion_optin`.");
 239         define_feature!(15, PaymentSecret, [InitContext, NodeContext],
 240                 "Feature flags for `payment_secret`.");
 241         define_feature!(17, BasicMPP, [InitContext, NodeContext],
 242                 "Feature flags for `basic_mpp`.");
 243
 244         #[cfg(test)]
 245         define_context!(TestingContext {
 246                 required_features: [
 247                         // Byte 0
 248                         ,
 249                         // Byte 1
 250                         ,
 251                         // Byte 2
 252                         UnknownFeature,
 253                 ],
 254                 optional_features: [
 255                         // Byte 0
 256                         ,
 257                         // Byte 1
 258                         ,
 259                         // Byte 2
 260                         ,
 261                 ],
 262         });
 263
 264         #[cfg(test)]
 265         define_feature!(23, UnknownFeature, [TestingContext],
 266                 "Feature flags for an unknown feature used in testing.");
 267 }
 268
 269 /// Tracks the set of features which a node implements, templated by the context in which it
 270 /// appears.
 271 pub struct Features<T: sealed::Context> {
 272         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
 273         flags: Vec<u8>,
 274         mark: PhantomData<T>,
 275 }
 276
 277 impl<T: sealed::Context> Clone for Features<T> {
 278         fn clone(&self) -> Self {
 279                 Self {
 280                         flags: self.flags.clone(),
 281                         mark: PhantomData,
 282                 }
 283         }
 284 }
 285 impl<T: sealed::Context> PartialEq for Features<T> {
 286         fn eq(&self, o: &Self) -> bool {
 287                 self.flags.eq(&o.flags)
 288         }
 289 }
 290 impl<T: sealed::Context> fmt::Debug for Features<T> {
 291         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 292                 self.flags.fmt(fmt)
 293         }
 294 }
 295
 296 /// Features used within an `init` message.
 297 pub type InitFeatures = Features<sealed::InitContext>;
 298 /// Features used within a `node_announcement` message.
 299 pub type NodeFeatures = Features<sealed::NodeContext>;
 300 /// Features used within a `channel_announcement` message.
 301 pub type ChannelFeatures = Features<sealed::ChannelContext>;
 302
 303 impl InitFeatures {
 304         /// Writes all features present up to, and including, 13.
 305         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
 306                 let len = cmp::min(2, self.flags.len());
 307                 w.size_hint(len + 2);
 308                 (len as u16).write(w)?;
 309                 for i in (0..len).rev() {
 310                         if i == 0 {
 311                                 self.flags[i].write(w)?;
 312                         } else {
 313                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
 314                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
 315                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
 316                         }
 317                 }
 318                 Ok(())
 319         }
 320
 321         /// or's another InitFeatures into this one.
 322         pub(crate) fn or(mut self, o: InitFeatures) -> InitFeatures {
 323                 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
 324                 self.flags.resize(total_feature_len, 0u8);
 325                 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
 326                         *byte |= *o_byte;
 327                 }
 328                 self
 329         }
 330
 331         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
 332         /// are included in the result.
 333         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 334                 self.to_context_internal()
 335         }
 336 }
 337
 338 impl<T: sealed::Context> Features<T> {
 339         /// Create a blank Features with no features set
 340         pub fn empty() -> Features<T> {
 341                 Features {
 342                         flags: Vec::new(),
 343                         mark: PhantomData,
 344                 }
 345         }
 346
 347         /// Creates features known by the implementation as defined by [`T::KNOWN_FEATURE_FLAGS`].
 348         ///
 349         /// [`T::KNOWN_FEATURE_FLAGS`]: sealed/trait.Context.html#associatedconstant.KNOWN_FEATURE_FLAGS
 350         pub fn known() -> Features<T> {
 351                 Self {
 352                         flags: T::KNOWN_FEATURE_FLAGS.to_vec(),
 353                         mark: PhantomData,
 354                 }
 355         }
 356
 357         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
 358         /// included in the result.
 359         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
 360                 let byte_count = C::KNOWN_FEATURE_MASK.len();
 361                 let mut flags = Vec::new();
 362                 for (i, byte) in self.flags.iter().enumerate() {
 363                         if i < byte_count {
 364                                 let known_source_features = T::KNOWN_FEATURE_MASK[i];
 365                                 let known_target_features = C::KNOWN_FEATURE_MASK[i];
 366                                 flags.push(byte & known_source_features & known_target_features);
 367                         }
 368                 }
 369                 Features::<C> { flags, mark: PhantomData, }
 370         }
 371
 372         #[cfg(test)]
 373         /// Create a Features given a set of flags, in LE.
 374         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 375                 Features {
 376                         flags,
 377                         mark: PhantomData,
 378                 }
 379         }
 380
 381         #[cfg(test)]
 382         /// Gets the underlying flags set, in LE.
 383         pub fn le_flags(&self) -> &Vec<u8> {
 384                 &self.flags
 385         }
 386
 387         pub(crate) fn requires_unknown_bits(&self) -> bool {
 388                 // Bitwise AND-ing with all even bits set except for known features will select required
 389                 // unknown features.
 390                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 391                 self.flags.iter().enumerate().any(|(i, &byte)| {
 392                         let required_features = 0b01_01_01_01;
 393                         let unknown_features = if i < byte_count {
 394                                 !T::KNOWN_FEATURE_MASK[i]
 395                         } else {
 396                                 0b11_11_11_11
 397                         };
 398                         (byte & (required_features & unknown_features)) != 0
 399                 })
 400         }
 401
 402         pub(crate) fn supports_unknown_bits(&self) -> bool {
 403                 // Bitwise AND-ing with all even and odd bits set except for known features will select
 404                 // both required and optional unknown features.
 405                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 406                 self.flags.iter().enumerate().any(|(i, &byte)| {
 407                         let unknown_features = if i < byte_count {
 408                                 !T::KNOWN_FEATURE_MASK[i]
 409                         } else {
 410                                 0b11_11_11_11
 411                         };
 412                         (byte & unknown_features) != 0
 413                 })
 414         }
 415
 416         /// The number of bytes required to represent the feature flags present. This does not include
 417         /// the length bytes which are included in the serialized form.
 418         pub(crate) fn byte_count(&self) -> usize {
 419                 self.flags.len()
 420         }
 421
 422         #[cfg(test)]
 423         pub(crate) fn set_required_unknown_bits(&mut self) {
 424                 <sealed::TestingContext as sealed::UnknownFeature>::set_required_bit(&mut self.flags);
 425         }
 426
 427         #[cfg(test)]
 428         pub(crate) fn set_optional_unknown_bits(&mut self) {
 429                 <sealed::TestingContext as sealed::UnknownFeature>::set_optional_bit(&mut self.flags);
 430         }
 431
 432         #[cfg(test)]
 433         pub(crate) fn clear_unknown_bits(&mut self) {
 434                 <sealed::TestingContext as sealed::UnknownFeature>::clear_bits(&mut self.flags);
 435         }
 436 }
 437
 438 impl<T: sealed::DataLossProtect> Features<T> {
 439         #[cfg(test)]
 440         pub(crate) fn requires_data_loss_protect(&self) -> bool {
 441                 <T as sealed::DataLossProtect>::requires_feature(&self.flags)
 442         }
 443         pub(crate) fn supports_data_loss_protect(&self) -> bool {
 444                 <T as sealed::DataLossProtect>::supports_feature(&self.flags)
 445         }
 446 }
 447
 448 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 449         #[cfg(test)]
 450         pub(crate) fn requires_upfront_shutdown_script(&self) -> bool {
 451                 <T as sealed::UpfrontShutdownScript>::requires_feature(&self.flags)
 452         }
 453         pub(crate) fn supports_upfront_shutdown_script(&self) -> bool {
 454                 <T as sealed::UpfrontShutdownScript>::supports_feature(&self.flags)
 455         }
 456         #[cfg(test)]
 457         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
 458                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
 459                 self
 460         }
 461 }
 462
 463 impl<T: sealed::VariableLengthOnion> Features<T> {
 464         #[cfg(test)]
 465         pub(crate) fn requires_variable_length_onion(&self) -> bool {
 466                 <T as sealed::VariableLengthOnion>::requires_feature(&self.flags)
 467         }
 468         pub(crate) fn supports_variable_length_onion(&self) -> bool {
 469                 <T as sealed::VariableLengthOnion>::supports_feature(&self.flags)
 470         }
 471 }
 472
 473 impl<T: sealed::InitialRoutingSync> Features<T> {
 474         pub(crate) fn initial_routing_sync(&self) -> bool {
 475                 <T as sealed::InitialRoutingSync>::supports_feature(&self.flags)
 476         }
 477         pub(crate) fn clear_initial_routing_sync(&mut self) {
 478                 <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags)
 479         }
 480 }
 481
 482 impl<T: sealed::PaymentSecret> Features<T> {
 483         #[cfg(test)]
 484         pub(crate) fn requires_payment_secret(&self) -> bool {
 485                 <T as sealed::PaymentSecret>::requires_feature(&self.flags)
 486         }
 487         // Note that we never need to test this since what really matters is the invoice - iff the
 488         // invoice provides a payment_secret, we assume that we can use it (ie that the recipient
 489         // supports payment_secret).
 490         #[allow(dead_code)]
 491         pub(crate) fn supports_payment_secret(&self) -> bool {
 492                 <T as sealed::PaymentSecret>::supports_feature(&self.flags)
 493         }
 494 }
 495
 496 impl<T: sealed::BasicMPP> Features<T> {
 497         #[cfg(test)]
 498         pub(crate) fn requires_basic_mpp(&self) -> bool {
 499                 <T as sealed::BasicMPP>::requires_feature(&self.flags)
 500         }
 501         // We currently never test for this since we don't actually *generate* multipath routes.
 502         #[allow(dead_code)]
 503         pub(crate) fn supports_basic_mpp(&self) -> bool {
 504                 <T as sealed::BasicMPP>::supports_feature(&self.flags)
 505         }
 506 }
 507
 508 impl<T: sealed::Context> Writeable for Features<T> {
 509         fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
 510                 w.size_hint(self.flags.len() + 2);
 511                 (self.flags.len() as u16).write(w)?;
 512                 for f in self.flags.iter().rev() { // Swap back to big-endian
 513                         f.write(w)?;
 514                 }
 515                 Ok(())
 516         }
 517 }
 518
 519 impl<T: sealed::Context> Readable for Features<T> {
 520         fn read<R: ::std::io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 521                 let mut flags: Vec<u8> = Readable::read(r)?;
 522                 flags.reverse(); // Swap to little-endian
 523                 Ok(Self {
 524                         flags,
 525                         mark: PhantomData,
 526                 })
 527         }
 528 }
 529
 530 #[cfg(test)]
 531 mod tests {
 532         use super::{ChannelFeatures, InitFeatures, NodeFeatures};
 533
 534         #[test]
 535         fn sanity_test_known_features() {
 536                 assert!(!ChannelFeatures::known().requires_unknown_bits());
 537                 assert!(!ChannelFeatures::known().supports_unknown_bits());
 538                 assert!(!InitFeatures::known().requires_unknown_bits());
 539                 assert!(!InitFeatures::known().supports_unknown_bits());
 540                 assert!(!NodeFeatures::known().requires_unknown_bits());
 541                 assert!(!NodeFeatures::known().supports_unknown_bits());
 542
 543                 assert!(InitFeatures::known().supports_upfront_shutdown_script());
 544                 assert!(NodeFeatures::known().supports_upfront_shutdown_script());
 545                 assert!(!InitFeatures::known().requires_upfront_shutdown_script());
 546                 assert!(!NodeFeatures::known().requires_upfront_shutdown_script());
 547
 548                 assert!(InitFeatures::known().supports_data_loss_protect());
 549                 assert!(NodeFeatures::known().supports_data_loss_protect());
 550                 assert!(!InitFeatures::known().requires_data_loss_protect());
 551                 assert!(!NodeFeatures::known().requires_data_loss_protect());
 552
 553                 assert!(InitFeatures::known().supports_variable_length_onion());
 554                 assert!(NodeFeatures::known().supports_variable_length_onion());
 555                 assert!(!InitFeatures::known().requires_variable_length_onion());
 556                 assert!(!NodeFeatures::known().requires_variable_length_onion());
 557
 558                 assert!(InitFeatures::known().supports_payment_secret());
 559                 assert!(NodeFeatures::known().supports_payment_secret());
 560                 assert!(!InitFeatures::known().requires_payment_secret());
 561                 assert!(!NodeFeatures::known().requires_payment_secret());
 562
 563                 assert!(InitFeatures::known().supports_basic_mpp());
 564                 assert!(NodeFeatures::known().supports_basic_mpp());
 565                 assert!(!InitFeatures::known().requires_basic_mpp());
 566                 assert!(!NodeFeatures::known().requires_basic_mpp());
 567
 568                 let mut init_features = InitFeatures::known();
 569                 assert!(init_features.initial_routing_sync());
 570                 init_features.clear_initial_routing_sync();
 571                 assert!(!init_features.initial_routing_sync());
 572         }
 573
 574         #[test]
 575         fn sanity_test_unknown_bits() {
 576                 let mut features = ChannelFeatures::empty();
 577                 assert!(!features.requires_unknown_bits());
 578                 assert!(!features.supports_unknown_bits());
 579
 580                 features.set_required_unknown_bits();
 581                 assert!(features.requires_unknown_bits());
 582                 assert!(features.supports_unknown_bits());
 583
 584                 features.clear_unknown_bits();
 585                 assert!(!features.requires_unknown_bits());
 586                 assert!(!features.supports_unknown_bits());
 587
 588                 features.set_optional_unknown_bits();
 589                 assert!(!features.requires_unknown_bits());
 590                 assert!(features.supports_unknown_bits());
 591         }
 592
 593         #[test]
 594         fn convert_to_context_with_relevant_flags() {
 595                 let init_features = InitFeatures::known().clear_upfront_shutdown_script();
 596                 assert!(init_features.initial_routing_sync());
 597                 assert!(!init_features.supports_upfront_shutdown_script());
 598
 599                 let node_features: NodeFeatures = init_features.to_context();
 600                 {
 601                         // Check that the flags are as expected:
 602                         // - option_data_loss_protect
 603                         // - var_onion_optin | payment_secret
 604                         // - basic_mpp
 605                         assert_eq!(node_features.flags.len(), 3);
 606                         assert_eq!(node_features.flags[0], 0b00000010);
 607                         assert_eq!(node_features.flags[1], 0b10000010);
 608                         assert_eq!(node_features.flags[2], 0b00000010);
 609                 }
 610
 611                 // Check that cleared flags are kept blank when converting back:
 612                 // - initial_routing_sync was not applicable to NodeContext
 613                 // - upfront_shutdown_script was cleared before converting
 614                 let features: InitFeatures = node_features.to_context_internal();
 615                 assert!(!features.initial_routing_sync());
 616                 assert!(!features.supports_upfront_shutdown_script());
 617         }
 618 }