_ 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 //! [BOLT #9]: https://github.com/lightningnetwork/lightning-rfc/blob/master/09-features.md
  23 //! [messages]: crate::ln::msgs
  24
  25 use prelude::*;
  26 use core::{cmp, fmt};
  27 use core::marker::PhantomData;
  28
  29 use bitcoin::bech32;
  30 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
  31 use ln::msgs::DecodeError;
  32 use util::ser::{Readable, Writeable, Writer};
  33
  34 mod sealed {
  35         use prelude::*;
  36         use ln::features::Features;
  37
  38         /// The context in which [`Features`] are applicable. Defines which features are required and
  39         /// which are optional for the context.
  40         pub trait Context {
  41                 /// Features that are known to the implementation, where a required feature is indicated by
  42                 /// its even bit and an optional feature is indicated by its odd bit.
  43                 const KNOWN_FEATURE_FLAGS: &'static [u8];
  44
  45                 /// Bitmask for selecting features that are known to the implementation, regardless of
  46                 /// whether each feature is required or optional.
  47                 const KNOWN_FEATURE_MASK: &'static [u8];
  48         }
  49
  50         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
  51         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
  52         /// feature identifiers.
  53         macro_rules! define_context {
  54                 ($context: ident {
  55                         required_features: [$( $( $required_feature: ident )|*, )*],
  56                         optional_features: [$( $( $optional_feature: ident )|*, )*],
  57                 }) => {
  58                         #[derive(Eq, PartialEq)]
  59                         pub struct $context {}
  60
  61                         impl Context for $context {
  62                                 const KNOWN_FEATURE_FLAGS: &'static [u8] = &[
  63                                         // For each byte, use bitwise-OR to compute the applicable flags for known
  64                                         // required features `r_i` and optional features `o_j` for all `i` and `j` such
  65                                         // that the following slice is formed:
  66                                         //
  67                                         // [
  68                                         //  `r_0` | `r_1` | ... | `o_0` | `o_1` | ...,
  69                                         //  ...,
  70                                         // ]
  71                                         $(
  72                                                 0b00_00_00_00 $(|
  73                                                         <Self as $required_feature>::REQUIRED_MASK)*
  74                                                 $(|
  75                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
  76                                         )*
  77                                 ];
  78
  79                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
  80                                         // Similar as above, but set both flags for each feature regardless of whether
  81                                         // the feature is required or optional.
  82                                         $(
  83                                                 0b00_00_00_00 $(|
  84                                                         <Self as $required_feature>::REQUIRED_MASK |
  85                                                         <Self as $required_feature>::OPTIONAL_MASK)*
  86                                                 $(|
  87                                                         <Self as $optional_feature>::REQUIRED_MASK |
  88                                                         <Self as $optional_feature>::OPTIONAL_MASK)*,
  89                                         )*
  90                                 ];
  91                         }
  92                 };
  93         }
  94
  95         define_context!(InitContext {
  96                 required_features: [
  97                         // Byte 0
  98                         ,
  99                         // Byte 1
 100                         VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 101                         // Byte 2
 102                         ,
 103                         // Byte 3
 104                         ,
 105                 ],
 106                 optional_features: [
 107                         // Byte 0
 108                         DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
 109                         // Byte 1
 110                         ,
 111                         // Byte 2
 112                         BasicMPP,
 113                         // Byte 3
 114                         ShutdownAnySegwit,
 115                 ],
 116         });
 117         define_context!(NodeContext {
 118                 required_features: [
 119                         // Byte 0
 120                         ,
 121                         // Byte 1
 122                         VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 123                         // Byte 2
 124                         ,
 125                         // Byte 3
 126                         ,
 127                 ],
 128                 optional_features: [
 129                         // Byte 0
 130                         DataLossProtect | UpfrontShutdownScript | GossipQueries,
 131                         // Byte 1
 132                         ,
 133                         // Byte 2
 134                         BasicMPP,
 135                         // Byte 3
 136                         ShutdownAnySegwit,
 137                 ],
 138         });
 139         define_context!(ChannelContext {
 140                 required_features: [],
 141                 optional_features: [],
 142         });
 143         define_context!(InvoiceContext {
 144                 required_features: [
 145                         // Byte 0
 146                         ,
 147                         // Byte 1
 148                         VariableLengthOnion | PaymentSecret,
 149                         // Byte 2
 150                         ,
 151                 ],
 152                 optional_features: [
 153                         // Byte 0
 154                         ,
 155                         // Byte 1
 156                         ,
 157                         // Byte 2
 158                         BasicMPP,
 159                 ],
 160         });
 161
 162         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
 163         /// useful for manipulating feature flags.
 164         macro_rules! define_feature {
 165                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 166                  $required_setter: ident) => {
 167                         #[doc = $doc]
 168                         ///
 169                         /// See [BOLT #9] for details.
 170                         ///
 171                         /// [BOLT #9]: https://github.com/lightningnetwork/lightning-rfc/blob/master/09-features.md
 172                         pub trait $feature: Context {
 173                                 /// The bit used to signify that the feature is required.
 174                                 const EVEN_BIT: usize = $odd_bit - 1;
 175
 176                                 /// The bit used to signify that the feature is optional.
 177                                 const ODD_BIT: usize = $odd_bit;
 178
 179                                 /// Assertion that [`EVEN_BIT`] is actually even.
 180                                 ///
 181                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
 182                                 const ASSERT_EVEN_BIT_PARITY: usize;
 183
 184                                 /// Assertion that [`ODD_BIT`] is actually odd.
 185                                 ///
 186                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
 187                                 const ASSERT_ODD_BIT_PARITY: usize;
 188
 189                                 /// The byte where the feature is set.
 190                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
 191
 192                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
 193                                 ///
 194                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 195                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
 196
 197                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
 198                                 ///
 199                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 200                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
 201
 202                                 /// Returns whether the feature is required by the given flags.
 203                                 #[inline]
 204                                 fn requires_feature(flags: &Vec<u8>) -> bool {
 205                                         flags.len() > Self::BYTE_OFFSET &&
 206                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
 207                                 }
 208
 209                                 /// Returns whether the feature is supported by the given flags.
 210                                 #[inline]
 211                                 fn supports_feature(flags: &Vec<u8>) -> bool {
 212                                         flags.len() > Self::BYTE_OFFSET &&
 213                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
 214                                 }
 215
 216                                 /// Sets the feature's required (even) bit in the given flags.
 217                                 #[inline]
 218                                 fn set_required_bit(flags: &mut Vec<u8>) {
 219                                         if flags.len() <= Self::BYTE_OFFSET {
 220                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 221                                         }
 222
 223                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
 224                                 }
 225
 226                                 /// Sets the feature's optional (odd) bit in the given flags.
 227                                 #[inline]
 228                                 fn set_optional_bit(flags: &mut Vec<u8>) {
 229                                         if flags.len() <= Self::BYTE_OFFSET {
 230                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 231                                         }
 232
 233                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
 234                                 }
 235
 236                                 /// Clears the feature's required (even) and optional (odd) bits from the given
 237                                 /// flags.
 238                                 #[inline]
 239                                 fn clear_bits(flags: &mut Vec<u8>) {
 240                                         if flags.len() > Self::BYTE_OFFSET {
 241                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
 242                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 243                                         }
 244
 245                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
 246                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
 247                                         flags.resize(size, 0u8);
 248                                 }
 249                         }
 250
 251                         impl <T: $feature> Features<T> {
 252                                 /// Set this feature as optional.
 253                                 pub fn $optional_setter(mut self) -> Self {
 254                                         <T as $feature>::set_optional_bit(&mut self.flags);
 255                                         self
 256                                 }
 257
 258                                 /// Set this feature as required.
 259                                 pub fn $required_setter(mut self) -> Self {
 260                                         <T as $feature>::set_required_bit(&mut self.flags);
 261                                         self
 262                                 }
 263                         }
 264
 265                         $(
 266                                 impl $feature for $context {
 267                                         // EVEN_BIT % 2 == 0
 268                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
 269
 270                                         // ODD_BIT % 2 == 1
 271                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
 272                                 }
 273                         )*
 274
 275                 }
 276         }
 277
 278         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
 279                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
 280                 set_data_loss_protect_required);
 281         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
 282         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
 283                 set_initial_routing_sync_optional, set_initial_routing_sync_required);
 284         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
 285                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
 286                 set_upfront_shutdown_script_required);
 287         define_feature!(7, GossipQueries, [InitContext, NodeContext],
 288                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required);
 289         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
 290                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
 291                 set_variable_length_onion_required);
 292         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext],
 293                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
 294                 set_static_remote_key_required);
 295         define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
 296                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required);
 297         define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext],
 298                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required);
 299         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
 300                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
 301                 set_shutdown_any_segwit_required);
 302
 303         #[cfg(test)]
 304         define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext],
 305                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
 306                 set_unknown_feature_required);
 307 }
 308
 309 /// Tracks the set of features which a node implements, templated by the context in which it
 310 /// appears.
 311 ///
 312 /// (C-not exported) as we map the concrete feature types below directly instead
 313 #[derive(Eq)]
 314 pub struct Features<T: sealed::Context> {
 315         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
 316         flags: Vec<u8>,
 317         mark: PhantomData<T>,
 318 }
 319
 320 impl<T: sealed::Context> Clone for Features<T> {
 321         fn clone(&self) -> Self {
 322                 Self {
 323                         flags: self.flags.clone(),
 324                         mark: PhantomData,
 325                 }
 326         }
 327 }
 328 impl<T: sealed::Context> PartialEq for Features<T> {
 329         fn eq(&self, o: &Self) -> bool {
 330                 self.flags.eq(&o.flags)
 331         }
 332 }
 333 impl<T: sealed::Context> fmt::Debug for Features<T> {
 334         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 335                 self.flags.fmt(fmt)
 336         }
 337 }
 338
 339 /// Features used within an `init` message.
 340 pub type InitFeatures = Features<sealed::InitContext>;
 341 /// Features used within a `node_announcement` message.
 342 pub type NodeFeatures = Features<sealed::NodeContext>;
 343 /// Features used within a `channel_announcement` message.
 344 pub type ChannelFeatures = Features<sealed::ChannelContext>;
 345 /// Features used within an invoice.
 346 pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
 347
 348 impl InitFeatures {
 349         /// Writes all features present up to, and including, 13.
 350         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
 351                 let len = cmp::min(2, self.flags.len());
 352                 w.size_hint(len + 2);
 353                 (len as u16).write(w)?;
 354                 for i in (0..len).rev() {
 355                         if i == 0 {
 356                                 self.flags[i].write(w)?;
 357                         } else {
 358                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
 359                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
 360                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
 361                         }
 362                 }
 363                 Ok(())
 364         }
 365
 366         /// or's another InitFeatures into this one.
 367         pub(crate) fn or(mut self, o: InitFeatures) -> InitFeatures {
 368                 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
 369                 self.flags.resize(total_feature_len, 0u8);
 370                 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
 371                         *byte |= *o_byte;
 372                 }
 373                 self
 374         }
 375
 376         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
 377         /// are included in the result.
 378         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 379                 self.to_context_internal()
 380         }
 381 }
 382
 383 impl InvoiceFeatures {
 384         /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
 385         /// context `C` are included in the result.
 386         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 387                 self.to_context_internal()
 388         }
 389 }
 390
 391 impl ToBase32 for InvoiceFeatures {
 392         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
 393                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
 394                 // minus one before dividing
 395                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
 396                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
 397                 for (byte_idx, byte) in self.flags.iter().enumerate() {
 398                         let bit_pos_from_left_0_indexed = byte_idx * 8;
 399                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
 400                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
 401                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
 402                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
 403                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
 404                         if new_u5_idx > 0 {
 405                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
 406                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
 407                         }
 408                         if new_u5_idx > 1 {
 409                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
 410                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
 411                         }
 412                 }
 413                 // Trim the highest feature bits.
 414                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
 415                         res_u5s.remove(0);
 416                 }
 417                 writer.write(&res_u5s)
 418         }
 419 }
 420
 421 impl Base32Len for InvoiceFeatures {
 422         fn base32_len(&self) -> usize {
 423                 self.to_base32().len()
 424         }
 425 }
 426
 427 impl FromBase32 for InvoiceFeatures {
 428         type Err = bech32::Error;
 429
 430         fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
 431                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
 432                 // minus one before dividing
 433                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
 434                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
 435                 for (u5_idx, chunk) in field_data.iter().enumerate() {
 436                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
 437                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
 438                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
 439                         let chunk_u16 = chunk.to_u8() as u16;
 440                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
 441                         if new_byte_idx != length_bytes - 1 {
 442                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
 443                         }
 444                 }
 445                 // Trim the highest feature bits.
 446                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
 447                         res_bytes.pop();
 448                 }
 449                 Ok(InvoiceFeatures::from_le_bytes(res_bytes))
 450         }
 451 }
 452
 453 impl<T: sealed::Context> Features<T> {
 454         /// Create a blank Features with no features set
 455         pub fn empty() -> Self {
 456                 Features {
 457                         flags: Vec::new(),
 458                         mark: PhantomData,
 459                 }
 460         }
 461
 462         /// Creates a Features with the bits set which are known by the implementation
 463         pub fn known() -> Self {
 464                 Self {
 465                         flags: T::KNOWN_FEATURE_FLAGS.to_vec(),
 466                         mark: PhantomData,
 467                 }
 468         }
 469
 470         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
 471         /// included in the result.
 472         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
 473                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
 474                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
 475                 let mut flags = Vec::new();
 476                 for (i, byte) in self.flags.iter().enumerate() {
 477                         if i < from_byte_count && i < to_byte_count {
 478                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
 479                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
 480                                 flags.push(byte & from_known_features & to_known_features);
 481                         }
 482                 }
 483                 Features::<C> { flags, mark: PhantomData, }
 484         }
 485
 486         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
 487         /// most on-the-wire encodings.
 488         /// (C-not exported) as we don't support export across multiple T
 489         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 490                 Features {
 491                         flags,
 492                         mark: PhantomData,
 493                 }
 494         }
 495
 496         #[cfg(test)]
 497         /// Gets the underlying flags set, in LE.
 498         pub fn le_flags(&self) -> &Vec<u8> {
 499                 &self.flags
 500         }
 501
 502         pub(crate) fn requires_unknown_bits(&self) -> bool {
 503                 // Bitwise AND-ing with all even bits set except for known features will select required
 504                 // unknown features.
 505                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 506                 self.flags.iter().enumerate().any(|(i, &byte)| {
 507                         let required_features = 0b01_01_01_01;
 508                         let unknown_features = if i < byte_count {
 509                                 !T::KNOWN_FEATURE_MASK[i]
 510                         } else {
 511                                 0b11_11_11_11
 512                         };
 513                         (byte & (required_features & unknown_features)) != 0
 514                 })
 515         }
 516
 517         pub(crate) fn supports_unknown_bits(&self) -> bool {
 518                 // Bitwise AND-ing with all even and odd bits set except for known features will select
 519                 // both required and optional unknown features.
 520                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 521                 self.flags.iter().enumerate().any(|(i, &byte)| {
 522                         let unknown_features = if i < byte_count {
 523                                 !T::KNOWN_FEATURE_MASK[i]
 524                         } else {
 525                                 0b11_11_11_11
 526                         };
 527                         (byte & unknown_features) != 0
 528                 })
 529         }
 530
 531         /// The number of bytes required to represent the feature flags present. This does not include
 532         /// the length bytes which are included in the serialized form.
 533         pub(crate) fn byte_count(&self) -> usize {
 534                 self.flags.len()
 535         }
 536 }
 537
 538 impl<T: sealed::DataLossProtect> Features<T> {
 539         #[cfg(test)]
 540         pub(crate) fn requires_data_loss_protect(&self) -> bool {
 541                 <T as sealed::DataLossProtect>::requires_feature(&self.flags)
 542         }
 543         pub(crate) fn supports_data_loss_protect(&self) -> bool {
 544                 <T as sealed::DataLossProtect>::supports_feature(&self.flags)
 545         }
 546 }
 547
 548 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 549         #[cfg(test)]
 550         pub(crate) fn requires_upfront_shutdown_script(&self) -> bool {
 551                 <T as sealed::UpfrontShutdownScript>::requires_feature(&self.flags)
 552         }
 553         pub(crate) fn supports_upfront_shutdown_script(&self) -> bool {
 554                 <T as sealed::UpfrontShutdownScript>::supports_feature(&self.flags)
 555         }
 556         #[cfg(test)]
 557         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
 558                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
 559                 self
 560         }
 561 }
 562
 563
 564 impl<T: sealed::GossipQueries> Features<T> {
 565         #[cfg(test)]
 566         pub(crate) fn requires_gossip_queries(&self) -> bool {
 567                 <T as sealed::GossipQueries>::requires_feature(&self.flags)
 568         }
 569         pub(crate) fn supports_gossip_queries(&self) -> bool {
 570                 <T as sealed::GossipQueries>::supports_feature(&self.flags)
 571         }
 572         #[cfg(test)]
 573         pub(crate) fn clear_gossip_queries(mut self) -> Self {
 574                 <T as sealed::GossipQueries>::clear_bits(&mut self.flags);
 575                 self
 576         }
 577 }
 578
 579 impl<T: sealed::VariableLengthOnion> Features<T> {
 580         #[cfg(test)]
 581         pub(crate) fn requires_variable_length_onion(&self) -> bool {
 582                 <T as sealed::VariableLengthOnion>::requires_feature(&self.flags)
 583         }
 584         pub(crate) fn supports_variable_length_onion(&self) -> bool {
 585                 <T as sealed::VariableLengthOnion>::supports_feature(&self.flags)
 586         }
 587 }
 588
 589 impl<T: sealed::StaticRemoteKey> Features<T> {
 590         pub(crate) fn supports_static_remote_key(&self) -> bool {
 591                 <T as sealed::StaticRemoteKey>::supports_feature(&self.flags)
 592         }
 593         #[cfg(test)]
 594         pub(crate) fn requires_static_remote_key(&self) -> bool {
 595                 <T as sealed::StaticRemoteKey>::requires_feature(&self.flags)
 596         }
 597 }
 598
 599 impl<T: sealed::InitialRoutingSync> Features<T> {
 600         pub(crate) fn initial_routing_sync(&self) -> bool {
 601                 <T as sealed::InitialRoutingSync>::supports_feature(&self.flags)
 602         }
 603         // We are no longer setting initial_routing_sync now that gossip_queries
 604         // is enabled. This feature is ignored by a peer when gossip_queries has
 605         // been negotiated.
 606         #[cfg(test)]
 607         pub(crate) fn clear_initial_routing_sync(&mut self) {
 608                 <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags)
 609         }
 610 }
 611
 612 impl<T: sealed::PaymentSecret> Features<T> {
 613         #[cfg(test)]
 614         pub(crate) fn requires_payment_secret(&self) -> bool {
 615                 <T as sealed::PaymentSecret>::requires_feature(&self.flags)
 616         }
 617         /// Returns whether the `payment_secret` feature is supported.
 618         pub fn supports_payment_secret(&self) -> bool {
 619                 <T as sealed::PaymentSecret>::supports_feature(&self.flags)
 620         }
 621 }
 622
 623 impl<T: sealed::BasicMPP> Features<T> {
 624         #[cfg(test)]
 625         pub(crate) fn requires_basic_mpp(&self) -> bool {
 626                 <T as sealed::BasicMPP>::requires_feature(&self.flags)
 627         }
 628         // We currently never test for this since we don't actually *generate* multipath routes.
 629         pub(crate) fn supports_basic_mpp(&self) -> bool {
 630                 <T as sealed::BasicMPP>::supports_feature(&self.flags)
 631         }
 632 }
 633
 634 impl<T: sealed::ShutdownAnySegwit> Features<T> {
 635         pub(crate) fn supports_shutdown_anysegwit(&self) -> bool {
 636                 <T as sealed::ShutdownAnySegwit>::supports_feature(&self.flags)
 637         }
 638         #[cfg(test)]
 639         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
 640                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
 641                 self
 642         }
 643 }
 644
 645 impl<T: sealed::Context> Writeable for Features<T> {
 646         fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
 647                 w.size_hint(self.flags.len() + 2);
 648                 (self.flags.len() as u16).write(w)?;
 649                 for f in self.flags.iter().rev() { // Swap back to big-endian
 650                         f.write(w)?;
 651                 }
 652                 Ok(())
 653         }
 654 }
 655
 656 impl<T: sealed::Context> Readable for Features<T> {
 657         fn read<R: ::std::io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 658                 let mut flags: Vec<u8> = Readable::read(r)?;
 659                 flags.reverse(); // Swap to little-endian
 660                 Ok(Self {
 661                         flags,
 662                         mark: PhantomData,
 663                 })
 664         }
 665 }
 666
 667 #[cfg(test)]
 668 mod tests {
 669         use super::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
 670         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
 671
 672         #[test]
 673         fn sanity_test_known_features() {
 674                 assert!(!ChannelFeatures::known().requires_unknown_bits());
 675                 assert!(!ChannelFeatures::known().supports_unknown_bits());
 676                 assert!(!InitFeatures::known().requires_unknown_bits());
 677                 assert!(!InitFeatures::known().supports_unknown_bits());
 678                 assert!(!NodeFeatures::known().requires_unknown_bits());
 679                 assert!(!NodeFeatures::known().supports_unknown_bits());
 680
 681                 assert!(InitFeatures::known().supports_upfront_shutdown_script());
 682                 assert!(NodeFeatures::known().supports_upfront_shutdown_script());
 683                 assert!(!InitFeatures::known().requires_upfront_shutdown_script());
 684                 assert!(!NodeFeatures::known().requires_upfront_shutdown_script());
 685
 686                 assert!(InitFeatures::known().supports_gossip_queries());
 687                 assert!(NodeFeatures::known().supports_gossip_queries());
 688                 assert!(!InitFeatures::known().requires_gossip_queries());
 689                 assert!(!NodeFeatures::known().requires_gossip_queries());
 690
 691                 assert!(InitFeatures::known().supports_data_loss_protect());
 692                 assert!(NodeFeatures::known().supports_data_loss_protect());
 693                 assert!(!InitFeatures::known().requires_data_loss_protect());
 694                 assert!(!NodeFeatures::known().requires_data_loss_protect());
 695
 696                 assert!(InitFeatures::known().supports_variable_length_onion());
 697                 assert!(NodeFeatures::known().supports_variable_length_onion());
 698                 assert!(InvoiceFeatures::known().supports_variable_length_onion());
 699                 assert!(InitFeatures::known().requires_variable_length_onion());
 700                 assert!(NodeFeatures::known().requires_variable_length_onion());
 701                 assert!(InvoiceFeatures::known().requires_variable_length_onion());
 702
 703                 assert!(InitFeatures::known().supports_static_remote_key());
 704                 assert!(NodeFeatures::known().supports_static_remote_key());
 705                 assert!(InitFeatures::known().requires_static_remote_key());
 706                 assert!(NodeFeatures::known().requires_static_remote_key());
 707
 708                 assert!(InitFeatures::known().supports_payment_secret());
 709                 assert!(NodeFeatures::known().supports_payment_secret());
 710                 assert!(InvoiceFeatures::known().supports_payment_secret());
 711                 assert!(InitFeatures::known().requires_payment_secret());
 712                 assert!(NodeFeatures::known().requires_payment_secret());
 713                 assert!(InvoiceFeatures::known().requires_payment_secret());
 714
 715                 assert!(InitFeatures::known().supports_basic_mpp());
 716                 assert!(NodeFeatures::known().supports_basic_mpp());
 717                 assert!(InvoiceFeatures::known().supports_basic_mpp());
 718                 assert!(!InitFeatures::known().requires_basic_mpp());
 719                 assert!(!NodeFeatures::known().requires_basic_mpp());
 720                 assert!(!InvoiceFeatures::known().requires_basic_mpp());
 721
 722                 assert!(InitFeatures::known().supports_shutdown_anysegwit());
 723                 assert!(NodeFeatures::known().supports_shutdown_anysegwit());
 724
 725                 let mut init_features = InitFeatures::known();
 726                 assert!(init_features.initial_routing_sync());
 727                 init_features.clear_initial_routing_sync();
 728                 assert!(!init_features.initial_routing_sync());
 729         }
 730
 731         #[test]
 732         fn sanity_test_unknown_bits() {
 733                 let features = ChannelFeatures::empty();
 734                 assert!(!features.requires_unknown_bits());
 735                 assert!(!features.supports_unknown_bits());
 736
 737                 let features = ChannelFeatures::empty().set_unknown_feature_required();
 738                 assert!(features.requires_unknown_bits());
 739                 assert!(features.supports_unknown_bits());
 740
 741                 let features = ChannelFeatures::empty().set_unknown_feature_optional();
 742                 assert!(!features.requires_unknown_bits());
 743                 assert!(features.supports_unknown_bits());
 744         }
 745
 746         #[test]
 747         fn convert_to_context_with_relevant_flags() {
 748                 let init_features = InitFeatures::known().clear_upfront_shutdown_script().clear_gossip_queries();
 749                 assert!(init_features.initial_routing_sync());
 750                 assert!(!init_features.supports_upfront_shutdown_script());
 751                 assert!(!init_features.supports_gossip_queries());
 752
 753                 let node_features: NodeFeatures = init_features.to_context();
 754                 {
 755                         // Check that the flags are as expected:
 756                         // - option_data_loss_protect
 757                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
 758                         // - basic_mpp
 759                         // - opt_shutdown_anysegwit
 760                         assert_eq!(node_features.flags.len(), 4);
 761                         assert_eq!(node_features.flags[0], 0b00000010);
 762                         assert_eq!(node_features.flags[1], 0b01010001);
 763                         assert_eq!(node_features.flags[2], 0b00000010);
 764                         assert_eq!(node_features.flags[3], 0b00001000);
 765                 }
 766
 767                 // Check that cleared flags are kept blank when converting back:
 768                 // - initial_routing_sync was not applicable to NodeContext
 769                 // - upfront_shutdown_script was cleared before converting
 770                 // - gossip_queries was cleared before converting
 771                 let features: InitFeatures = node_features.to_context_internal();
 772                 assert!(!features.initial_routing_sync());
 773                 assert!(!features.supports_upfront_shutdown_script());
 774                 assert!(!init_features.supports_gossip_queries());
 775         }
 776
 777         #[test]
 778         fn set_feature_bits() {
 779                 let features = InvoiceFeatures::empty()
 780                         .set_basic_mpp_optional()
 781                         .set_payment_secret_required();
 782                 assert!(features.supports_basic_mpp());
 783                 assert!(!features.requires_basic_mpp());
 784                 assert!(features.requires_payment_secret());
 785                 assert!(features.supports_payment_secret());
 786         }
 787
 788         #[test]
 789         fn invoice_features_encoding() {
 790                 let features_as_u5s = vec![
 791                         u5::try_from_u8(6).unwrap(),
 792                         u5::try_from_u8(10).unwrap(),
 793                         u5::try_from_u8(25).unwrap(),
 794                         u5::try_from_u8(1).unwrap(),
 795                         u5::try_from_u8(10).unwrap(),
 796                         u5::try_from_u8(0).unwrap(),
 797                         u5::try_from_u8(20).unwrap(),
 798                         u5::try_from_u8(2).unwrap(),
 799                         u5::try_from_u8(0).unwrap(),
 800                         u5::try_from_u8(6).unwrap(),
 801                         u5::try_from_u8(0).unwrap(),
 802                         u5::try_from_u8(16).unwrap(),
 803                         u5::try_from_u8(1).unwrap(),
 804                 ];
 805                 let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
 806
 807                 // Test length calculation.
 808                 assert_eq!(features.base32_len(), 13);
 809
 810                 // Test serialization.
 811                 let features_serialized = features.to_base32();
 812                 assert_eq!(features_as_u5s, features_serialized);
 813
 814                 // Test deserialization.
 815                 let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
 816                 assert_eq!(features, features_deserialized);
 817         }
 818 }