git.bitcoin.ninja 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 //! - `PaymentMetadata` - include additional data in invoices which is passed to recipients in the
  54 //!      onion.
  55 //!      (see [BOLT-11](https://github.com/lightning/bolts/blob/master/11-payment-encoding.md) for
  56 //!      more).
  57 //! - `ZeroConf` - supports accepting HTLCs and using channels prior to funding confirmation
  58 //!      (see
  59 //!      [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-channel_ready-message)
  60 //!      for more info).
  61 //! - `Keysend` - send funds to a node without an invoice
  62 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
  63 //! - `AnchorsZeroFeeHtlcTx` - requires/supports that commitment transactions include anchor outputs
  64 //!     and HTLC transactions are pre-signed with zero fee (see
  65 //!     [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more
  66 //!     information).
  67 //!
  68 //! LDK knows about the following features, but does not support them:
  69 //! - `AnchorsNonzeroFeeHtlcTx` - the initial version of anchor outputs, which was later found to be
  70 //!     vulnerable (see this
  71 //!     [mailing list post](https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-September/002796.html)
  72 //!     for more information).
  73 //!
  74 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
  75 //! [messages]: crate::ln::msgs
  76
  77 use crate::{io, io_extras};
  78 use crate::prelude::*;
  79 use core::{cmp, fmt};
  80 use core::borrow::Borrow;
  81 use core::hash::{Hash, Hasher};
  82 use core::marker::PhantomData;
  83
  84 use bitcoin::bech32;
  85 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
  86 use crate::ln::msgs::DecodeError;
  87 use crate::util::ser::{Readable, WithoutLength, Writeable, Writer};
  88
  89 mod sealed {
  90         use crate::prelude::*;
  91         use crate::ln::features::Features;
  92
  93         /// The context in which [`Features`] are applicable. Defines which features are known to the
  94         /// implementation, though specification of them as required or optional is up to the code
  95         /// constructing a features object.
  96         pub trait Context {
  97                 /// Bitmask for selecting features that are known to the implementation.
  98                 const KNOWN_FEATURE_MASK: &'static [u8];
  99         }
 100
 101         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
 102         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
 103         /// feature identifiers.
 104         macro_rules! define_context {
 105                 ($context: ident, [$( $( $known_feature: ident )|*, )*]) => {
 106                         #[derive(Eq, PartialEq)]
 107                         pub struct $context {}
 108
 109                         impl Context for $context {
 110                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
 111                                         $(
 112                                                 0b00_00_00_00 $(|
 113                                                         <Self as $known_feature>::REQUIRED_MASK |
 114                                                         <Self as $known_feature>::OPTIONAL_MASK)*,
 115                                         )*
 116                                 ];
 117                         }
 118
 119                         impl alloc::fmt::Display for Features<$context> {
 120                                 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
 121                                         $(
 122                                                 $(
 123                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($known_feature),
 124                                                                 if <$context as $known_feature>::requires_feature(&self.flags) { "required" }
 125                                                                 else if <$context as $known_feature>::supports_feature(&self.flags) { "supported" }
 126                                                                 else { "not supported" }))?;
 127                                                 )*
 128                                                 {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
 129                                         )*
 130                                         fmt.write_fmt(format_args!("unknown flags: {}",
 131                                                 if self.requires_unknown_bits() { "required" }
 132                                                 else if self.supports_unknown_bits() { "supported" } else { "none" }))
 133                                 }
 134                         }
 135                 };
 136         }
 137
 138         define_context!(InitContext, [
 139                 // Byte 0
 140                 DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
 141                 // Byte 1
 142                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 143                 // Byte 2
 144                 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
 145                 // Byte 3
 146                 ShutdownAnySegwit | Taproot,
 147                 // Byte 4
 148                 OnionMessages,
 149                 // Byte 5
 150                 ChannelType | SCIDPrivacy,
 151                 // Byte 6
 152                 ZeroConf,
 153         ]);
 154         define_context!(NodeContext, [
 155                 // Byte 0
 156                 DataLossProtect | UpfrontShutdownScript | GossipQueries,
 157                 // Byte 1
 158                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 159                 // Byte 2
 160                 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
 161                 // Byte 3
 162                 ShutdownAnySegwit | Taproot,
 163                 // Byte 4
 164                 OnionMessages,
 165                 // Byte 5
 166                 ChannelType | SCIDPrivacy,
 167                 // Byte 6
 168                 ZeroConf | Keysend,
 169         ]);
 170         define_context!(ChannelContext, []);
 171         define_context!(Bolt11InvoiceContext, [
 172                 // Byte 0
 173                 ,
 174                 // Byte 1
 175                 VariableLengthOnion | PaymentSecret,
 176                 // Byte 2
 177                 BasicMPP,
 178                 // Byte 3
 179                 ,
 180                 // Byte 4
 181                 ,
 182                 // Byte 5
 183                 ,
 184                 // Byte 6
 185                 PaymentMetadata,
 186         ]);
 187         define_context!(OfferContext, []);
 188         define_context!(InvoiceRequestContext, []);
 189         define_context!(Bolt12InvoiceContext, [
 190                 // Byte 0
 191                 ,
 192                 // Byte 1
 193                 ,
 194                 // Byte 2
 195                 BasicMPP,
 196         ]);
 197         define_context!(BlindedHopContext, []);
 198         // This isn't a "real" feature context, and is only used in the channel_type field in an
 199         // `OpenChannel` message.
 200         define_context!(ChannelTypeContext, [
 201                 // Byte 0
 202                 ,
 203                 // Byte 1
 204                 StaticRemoteKey,
 205                 // Byte 2
 206                 AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
 207                 // Byte 3
 208                 Taproot,
 209                 // Byte 4
 210                 ,
 211                 // Byte 5
 212                 SCIDPrivacy,
 213                 // Byte 6
 214                 ZeroConf,
 215         ]);
 216
 217         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
 218         /// useful for manipulating feature flags.
 219         macro_rules! define_feature {
 220                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 221                  $required_setter: ident, $supported_getter: ident) => {
 222                         #[doc = $doc]
 223                         ///
 224                         /// See [BOLT #9] for details.
 225                         ///
 226                         /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 227                         pub trait $feature: Context {
 228                                 /// The bit used to signify that the feature is required.
 229                                 const EVEN_BIT: usize = $odd_bit - 1;
 230
 231                                 /// The bit used to signify that the feature is optional.
 232                                 const ODD_BIT: usize = $odd_bit;
 233
 234                                 /// Assertion that [`EVEN_BIT`] is actually even.
 235                                 ///
 236                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
 237                                 const ASSERT_EVEN_BIT_PARITY: usize;
 238
 239                                 /// Assertion that [`ODD_BIT`] is actually odd.
 240                                 ///
 241                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
 242                                 const ASSERT_ODD_BIT_PARITY: usize;
 243
 244                                 /// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
 245                                 ///
 246                                 /// [`KNOWN_FEATURE_MASK`]: Context::KNOWN_FEATURE_MASK
 247                                 #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
 248                                 const ASSERT_BITS_IN_MASK: u8;
 249
 250                                 /// The byte where the feature is set.
 251                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
 252
 253                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
 254                                 ///
 255                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 256                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
 257
 258                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
 259                                 ///
 260                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 261                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
 262
 263                                 /// Returns whether the feature is required by the given flags.
 264                                 #[inline]
 265                                 fn requires_feature(flags: &Vec<u8>) -> bool {
 266                                         flags.len() > Self::BYTE_OFFSET &&
 267                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
 268                                 }
 269
 270                                 /// Returns whether the feature is supported by the given flags.
 271                                 #[inline]
 272                                 fn supports_feature(flags: &Vec<u8>) -> bool {
 273                                         flags.len() > Self::BYTE_OFFSET &&
 274                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
 275                                 }
 276
 277                                 /// Sets the feature's required (even) bit in the given flags.
 278                                 #[inline]
 279                                 fn set_required_bit(flags: &mut Vec<u8>) {
 280                                         if flags.len() <= Self::BYTE_OFFSET {
 281                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 282                                         }
 283
 284                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
 285                                         flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 286                                 }
 287
 288                                 /// Sets the feature's optional (odd) bit in the given flags.
 289                                 #[inline]
 290                                 fn set_optional_bit(flags: &mut Vec<u8>) {
 291                                         if flags.len() <= Self::BYTE_OFFSET {
 292                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 293                                         }
 294
 295                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
 296                                 }
 297
 298                                 /// Clears the feature's required (even) and optional (odd) bits from the given
 299                                 /// flags.
 300                                 #[inline]
 301                                 fn clear_bits(flags: &mut Vec<u8>) {
 302                                         if flags.len() > Self::BYTE_OFFSET {
 303                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
 304                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 305                                         }
 306
 307                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
 308                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
 309                                         flags.resize(size, 0u8);
 310                                 }
 311                         }
 312
 313                         impl <T: $feature> Features<T> {
 314                                 /// Set this feature as optional.
 315                                 pub fn $optional_setter(&mut self) {
 316                                         <T as $feature>::set_optional_bit(&mut self.flags);
 317                                 }
 318
 319                                 /// Set this feature as required.
 320                                 pub fn $required_setter(&mut self) {
 321                                         <T as $feature>::set_required_bit(&mut self.flags);
 322                                 }
 323
 324                                 /// Checks if this feature is supported.
 325                                 pub fn $supported_getter(&self) -> bool {
 326                                         <T as $feature>::supports_feature(&self.flags)
 327                                 }
 328                         }
 329
 330                         $(
 331                                 impl $feature for $context {
 332                                         // EVEN_BIT % 2 == 0
 333                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
 334
 335                                         // ODD_BIT % 2 == 1
 336                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
 337
 338                                         // (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
 339                                         #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
 340                                         const ASSERT_BITS_IN_MASK: u8 =
 341                                                 ((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
 342                                                  >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
 343                                 }
 344                         )*
 345                 };
 346                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 347                  $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
 348                         define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
 349                         impl <T: $feature> Features<T> {
 350                                 /// Checks if this feature is required.
 351                                 pub fn $required_getter(&self) -> bool {
 352                                         <T as $feature>::requires_feature(&self.flags)
 353                                 }
 354                         }
 355                 }
 356         }
 357
 358         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
 359                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
 360                 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
 361         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
 362         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
 363                 set_initial_routing_sync_optional, set_initial_routing_sync_required,
 364                 initial_routing_sync);
 365         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
 366                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
 367                 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
 368                 requires_upfront_shutdown_script);
 369         define_feature!(7, GossipQueries, [InitContext, NodeContext],
 370                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
 371                 supports_gossip_queries, requires_gossip_queries);
 372         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, Bolt11InvoiceContext],
 373                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
 374                 set_variable_length_onion_required, supports_variable_length_onion,
 375                 requires_variable_length_onion);
 376         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
 377                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
 378                 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
 379         define_feature!(15, PaymentSecret, [InitContext, NodeContext, Bolt11InvoiceContext],
 380                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
 381                 supports_payment_secret, requires_payment_secret);
 382         define_feature!(17, BasicMPP, [InitContext, NodeContext, Bolt11InvoiceContext, Bolt12InvoiceContext],
 383                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
 384                 supports_basic_mpp, requires_basic_mpp);
 385         define_feature!(19, Wumbo, [InitContext, NodeContext],
 386                 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
 387                 supports_wumbo, requires_wumbo);
 388         define_feature!(21, AnchorsNonzeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
 389                 "Feature flags for `option_anchors_nonzero_fee_htlc_tx`.", set_anchors_nonzero_fee_htlc_tx_optional,
 390                 set_anchors_nonzero_fee_htlc_tx_required, supports_anchors_nonzero_fee_htlc_tx, requires_anchors_nonzero_fee_htlc_tx);
 391         define_feature!(23, AnchorsZeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
 392                 "Feature flags for `option_anchors_zero_fee_htlc_tx`.", set_anchors_zero_fee_htlc_tx_optional,
 393                 set_anchors_zero_fee_htlc_tx_required, supports_anchors_zero_fee_htlc_tx, requires_anchors_zero_fee_htlc_tx);
 394         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
 395                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
 396                 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
 397         define_feature!(31, Taproot, [InitContext, NodeContext, ChannelTypeContext],
 398                 "Feature flags for `option_taproot`.", set_taproot_optional,
 399                 set_taproot_required, supports_taproot, requires_taproot);
 400         define_feature!(39, OnionMessages, [InitContext, NodeContext],
 401                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
 402                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
 403         define_feature!(45, ChannelType, [InitContext, NodeContext],
 404                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
 405                 set_channel_type_required, supports_channel_type, requires_channel_type);
 406         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
 407                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
 408                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
 409         define_feature!(49, PaymentMetadata, [Bolt11InvoiceContext],
 410                 "Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
 411                 set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
 412         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
 413                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
 414                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
 415         define_feature!(55, Keysend, [NodeContext],
 416                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
 417                 supports_keysend, requires_keysend);
 418         // Note: update the module-level docs when a new feature bit is added!
 419
 420         #[cfg(test)]
 421         define_feature!(123456789, UnknownFeature,
 422                 [NodeContext, ChannelContext, Bolt11InvoiceContext, OfferContext, InvoiceRequestContext, Bolt12InvoiceContext, BlindedHopContext],
 423                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
 424                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
 425 }
 426
 427 /// Tracks the set of features which a node implements, templated by the context in which it
 428 /// appears.
 429 ///
 430 /// This is not exported to bindings users as we map the concrete feature types below directly instead
 431 #[derive(Eq)]
 432 pub struct Features<T: sealed::Context> {
 433         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
 434         flags: Vec<u8>,
 435         mark: PhantomData<T>,
 436 }
 437
 438 impl<T: sealed::Context, Rhs: Borrow<Self>> core::ops::BitOrAssign<Rhs> for Features<T> {
 439         fn bitor_assign(&mut self, rhs: Rhs) {
 440                 let total_feature_len = cmp::max(self.flags.len(), rhs.borrow().flags.len());
 441                 self.flags.resize(total_feature_len, 0u8);
 442                 for (byte, rhs_byte) in self.flags.iter_mut().zip(rhs.borrow().flags.iter()) {
 443                         *byte |= *rhs_byte;
 444                 }
 445         }
 446 }
 447
 448 impl<T: sealed::Context> core::ops::BitOr for Features<T> {
 449         type Output = Self;
 450
 451         fn bitor(mut self, o: Self) -> Self {
 452                 self |= o;
 453                 self
 454         }
 455 }
 456
 457 impl<T: sealed::Context> Clone for Features<T> {
 458         fn clone(&self) -> Self {
 459                 Self {
 460                         flags: self.flags.clone(),
 461                         mark: PhantomData,
 462                 }
 463         }
 464 }
 465 impl<T: sealed::Context> Hash for Features<T> {
 466         fn hash<H: Hasher>(&self, hasher: &mut H) {
 467                 self.flags.hash(hasher);
 468         }
 469 }
 470 impl<T: sealed::Context> PartialEq for Features<T> {
 471         fn eq(&self, o: &Self) -> bool {
 472                 self.flags.eq(&o.flags)
 473         }
 474 }
 475 impl<T: sealed::Context> PartialOrd for Features<T> {
 476         fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
 477                 self.flags.partial_cmp(&other.flags)
 478         }
 479 }
 480 impl<T: sealed::Context + Eq> Ord for Features<T> {
 481         fn cmp(&self, other: &Self) -> cmp::Ordering {
 482                 self.flags.cmp(&other.flags)
 483         }
 484 }
 485 impl<T: sealed::Context> fmt::Debug for Features<T> {
 486         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 487                 self.flags.fmt(fmt)
 488         }
 489 }
 490
 491 /// Features used within an `init` message.
 492 pub type InitFeatures = Features<sealed::InitContext>;
 493 /// Features used within a `node_announcement` message.
 494 pub type NodeFeatures = Features<sealed::NodeContext>;
 495 /// Features used within a `channel_announcement` message.
 496 pub type ChannelFeatures = Features<sealed::ChannelContext>;
 497 /// Features used within an invoice.
 498 pub type Bolt11InvoiceFeatures = Features<sealed::Bolt11InvoiceContext>;
 499 /// Features used within an `offer`.
 500 pub type OfferFeatures = Features<sealed::OfferContext>;
 501 /// Features used within an `invoice_request`.
 502 pub type InvoiceRequestFeatures = Features<sealed::InvoiceRequestContext>;
 503 /// Features used within an `invoice`.
 504 pub type Bolt12InvoiceFeatures = Features<sealed::Bolt12InvoiceContext>;
 505 /// Features used within BOLT 4 encrypted_data_tlv and BOLT 12 blinded_payinfo
 506 pub type BlindedHopFeatures = Features<sealed::BlindedHopContext>;
 507
 508 /// Features used within the channel_type field in an OpenChannel message.
 509 ///
 510 /// A channel is always of some known "type", describing the transaction formats used and the exact
 511 /// semantics of our interaction with our peer.
 512 ///
 513 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
 514 /// the counterparty, only required features are allowed here.
 515 ///
 516 /// This is serialized differently from other feature types - it is not prefixed by a length, and
 517 /// thus must only appear inside a TLV where its length is known in advance.
 518 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
 519
 520 impl InitFeatures {
 521         /// Writes all features present up to, and including, 13.
 522         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 523                 let len = cmp::min(2, self.flags.len());
 524                 (len as u16).write(w)?;
 525                 for i in (0..len).rev() {
 526                         if i == 0 {
 527                                 self.flags[i].write(w)?;
 528                         } else {
 529                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
 530                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
 531                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
 532                         }
 533                 }
 534                 Ok(())
 535         }
 536
 537         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
 538         /// are included in the result.
 539         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 540                 self.to_context_internal()
 541         }
 542 }
 543
 544 impl Bolt11InvoiceFeatures {
 545         /// Converts `Bolt11InvoiceFeatures` to `Features<C>`. Only known `Bolt11InvoiceFeatures` relevant to
 546         /// context `C` are included in the result.
 547         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 548                 self.to_context_internal()
 549         }
 550
 551         /// Getting a route for a keysend payment to a private node requires providing the payee's
 552         /// features (since they were not announced in a node announcement). However, keysend payments
 553         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
 554         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
 555         /// `Bolt11InvoiceFeatures` for [`find_route`].
 556         ///
 557         /// MPP keysend is not widely supported yet, so we parameterize support to allow the user to
 558         /// choose whether their router should find multi-part routes.
 559         ///
 560         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
 561         /// [`find_route`]: crate::routing::router::find_route
 562         pub(crate) fn for_keysend(allow_mpp: bool) -> Bolt11InvoiceFeatures {
 563                 let mut res = Bolt11InvoiceFeatures::empty();
 564                 res.set_variable_length_onion_optional();
 565                 if allow_mpp {
 566                         res.set_basic_mpp_optional();
 567                 }
 568                 res
 569         }
 570 }
 571
 572 impl Bolt12InvoiceFeatures {
 573         /// Converts [`Bolt12InvoiceFeatures`] to [`Features<C>`]. Only known [`Bolt12InvoiceFeatures`]
 574         /// relevant to context `C` are included in the result.
 575         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 576                 self.to_context_internal()
 577         }
 578 }
 579
 580 impl ChannelTypeFeatures {
 581         // Maps the relevant `InitFeatures` to `ChannelTypeFeatures`. Any unknown features to
 582         // `ChannelTypeFeatures` are not included in the result.
 583         pub(crate) fn from_init(init: &InitFeatures) -> Self {
 584                 let mut ret = init.to_context_internal();
 585                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
 586                 // optional bits and then AND out the optional ones.
 587                 for byte in ret.flags.iter_mut() {
 588                         *byte |= (*byte & 0b10_10_10_10) >> 1;
 589                         *byte &= 0b01_01_01_01;
 590                 }
 591                 ret
 592         }
 593
 594         /// Constructs a ChannelTypeFeatures with only static_remotekey set
 595         pub(crate) fn only_static_remote_key() -> Self {
 596                 let mut ret = Self::empty();
 597                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
 598                 ret
 599         }
 600
 601         /// Constructs a ChannelTypeFeatures with anchors support
 602         pub(crate) fn anchors_zero_htlc_fee_and_dependencies() -> Self {
 603                 let mut ret = Self::empty();
 604                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
 605                 <sealed::ChannelTypeContext as sealed::AnchorsZeroFeeHtlcTx>::set_required_bit(&mut ret.flags);
 606                 ret
 607         }
 608 }
 609
 610 impl ToBase32 for Bolt11InvoiceFeatures {
 611         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
 612                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
 613                 // minus one before dividing
 614                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
 615                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
 616                 for (byte_idx, byte) in self.flags.iter().enumerate() {
 617                         let bit_pos_from_left_0_indexed = byte_idx * 8;
 618                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
 619                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
 620                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
 621                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
 622                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
 623                         if new_u5_idx > 0 {
 624                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
 625                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
 626                         }
 627                         if new_u5_idx > 1 {
 628                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
 629                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
 630                         }
 631                 }
 632                 // Trim the highest feature bits.
 633                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
 634                         res_u5s.remove(0);
 635                 }
 636                 writer.write(&res_u5s)
 637         }
 638 }
 639
 640 impl Base32Len for Bolt11InvoiceFeatures {
 641         fn base32_len(&self) -> usize {
 642                 self.to_base32().len()
 643         }
 644 }
 645
 646 impl FromBase32 for Bolt11InvoiceFeatures {
 647         type Err = bech32::Error;
 648
 649         fn from_base32(field_data: &[u5]) -> Result<Bolt11InvoiceFeatures, bech32::Error> {
 650                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
 651                 // minus one before dividing
 652                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
 653                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
 654                 for (u5_idx, chunk) in field_data.iter().enumerate() {
 655                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
 656                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
 657                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
 658                         let chunk_u16 = chunk.to_u8() as u16;
 659                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
 660                         if new_byte_idx != length_bytes - 1 {
 661                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
 662                         }
 663                 }
 664                 // Trim the highest feature bits.
 665                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
 666                         res_bytes.pop();
 667                 }
 668                 Ok(Bolt11InvoiceFeatures::from_le_bytes(res_bytes))
 669         }
 670 }
 671
 672 impl<T: sealed::Context> Features<T> {
 673         /// Create a blank Features with no features set
 674         pub fn empty() -> Self {
 675                 Features {
 676                         flags: Vec::new(),
 677                         mark: PhantomData,
 678                 }
 679         }
 680
 681         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
 682         /// included in the result.
 683         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
 684                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
 685                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
 686                 let mut flags = Vec::new();
 687                 for (i, byte) in self.flags.iter().enumerate() {
 688                         if i < from_byte_count && i < to_byte_count {
 689                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
 690                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
 691                                 flags.push(byte & from_known_features & to_known_features);
 692                         }
 693                 }
 694                 Features::<C> { flags, mark: PhantomData, }
 695         }
 696
 697         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
 698         /// most on-the-wire encodings.
 699         ///
 700         /// This is not exported to bindings users as we don't support export across multiple T
 701         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 702                 Features {
 703                         flags,
 704                         mark: PhantomData,
 705                 }
 706         }
 707
 708         #[cfg(test)]
 709         /// Gets the underlying flags set, in LE.
 710         pub fn le_flags(&self) -> &Vec<u8> {
 711                 &self.flags
 712         }
 713
 714         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 715                 for f in self.flags.iter().rev() { // Swap back to big-endian
 716                         f.write(w)?;
 717                 }
 718                 Ok(())
 719         }
 720
 721         /// Create a [`Features`] given a set of flags, in big-endian. This is in byte order from
 722         /// most on-the-wire encodings.
 723         ///
 724         /// This is not exported to bindings users as we don't support export across multiple T
 725         pub fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
 726                 flags.reverse(); // Swap to little-endian
 727                 Self {
 728                         flags,
 729                         mark: PhantomData,
 730                 }
 731         }
 732
 733         pub(crate) fn supports_any_optional_bits(&self) -> bool {
 734                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
 735         }
 736
 737         /// Returns true if this `Features` object contains required features unknown by `other`.
 738         pub fn requires_unknown_bits_from(&self, other: &Self) -> bool {
 739                 // Bitwise AND-ing with all even bits set except for known features will select required
 740                 // unknown features.
 741                 self.flags.iter().enumerate().any(|(i, &byte)| {
 742                         const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
 743                         const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
 744                         let unknown_features = if i < other.flags.len() {
 745                                 // Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
 746                                 !(other.flags[i]
 747                                         | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
 748                                         | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
 749                         } else {
 750                                 0b11_11_11_11
 751                         };
 752                         (byte & (REQUIRED_FEATURES & unknown_features)) != 0
 753                 })
 754         }
 755
 756         /// Returns true if this `Features` object contains unknown feature flags which are set as
 757         /// "required".
 758         pub fn requires_unknown_bits(&self) -> bool {
 759                 // Bitwise AND-ing with all even bits set except for known features will select required
 760                 // unknown features.
 761                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 762                 self.flags.iter().enumerate().any(|(i, &byte)| {
 763                         let required_features = 0b01_01_01_01;
 764                         let unknown_features = if i < byte_count {
 765                                 !T::KNOWN_FEATURE_MASK[i]
 766                         } else {
 767                                 0b11_11_11_11
 768                         };
 769                         (byte & (required_features & unknown_features)) != 0
 770                 })
 771         }
 772
 773         pub(crate) fn supports_unknown_bits(&self) -> bool {
 774                 // Bitwise AND-ing with all even and odd bits set except for known features will select
 775                 // both required and optional unknown features.
 776                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 777                 self.flags.iter().enumerate().any(|(i, &byte)| {
 778                         let unknown_features = if i < byte_count {
 779                                 !T::KNOWN_FEATURE_MASK[i]
 780                         } else {
 781                                 0b11_11_11_11
 782                         };
 783                         (byte & unknown_features) != 0
 784                 })
 785         }
 786
 787         // Returns true if the features within `self` are a subset of the features within `other`.
 788         pub(crate) fn is_subset(&self, other: &Self) -> bool {
 789                 for (idx, byte) in self.flags.iter().enumerate() {
 790                         if let Some(other_byte) = other.flags.get(idx) {
 791                                 if byte & other_byte != *byte {
 792                                         // `self` has bits set that `other` doesn't.
 793                                         return false;
 794                                 }
 795                         } else {
 796                                 if *byte > 0 {
 797                                         // `self` has a non-zero byte that `other` doesn't.
 798                                         return false;
 799                                 }
 800                         }
 801                 }
 802                 true
 803         }
 804
 805         /// Sets a required feature bit. Errors if `bit` is outside the feature range as defined
 806         /// by [BOLT 9].
 807         ///
 808         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
 809         /// be set instead (i.e., `bit - 1`).
 810         ///
 811         /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
 812         pub fn set_required_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
 813                 self.set_feature_bit(bit - (bit % 2))
 814         }
 815
 816         /// Sets an optional feature bit. Errors if `bit` is outside the feature range as defined
 817         /// by [BOLT 9].
 818         ///
 819         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
 820         /// set instead (i.e., `bit + 1`).
 821         ///
 822         /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
 823         pub fn set_optional_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
 824                 self.set_feature_bit(bit + (1 - (bit % 2)))
 825         }
 826
 827         fn set_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
 828                 if bit > 255 {
 829                         return Err(());
 830                 }
 831                 self.set_bit(bit, false)
 832         }
 833
 834         /// Sets a required custom feature bit. Errors if `bit` is outside the custom range as defined
 835         /// by [bLIP 2] or if it is a known `T` feature.
 836         ///
 837         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
 838         /// be set instead (i.e., `bit - 1`).
 839         ///
 840         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
 841         pub fn set_required_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
 842                 self.set_custom_bit(bit - (bit % 2))
 843         }
 844
 845         /// Sets an optional custom feature bit. Errors if `bit` is outside the custom range as defined
 846         /// by [bLIP 2] or if it is a known `T` feature.
 847         ///
 848         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
 849         /// set instead (i.e., `bit + 1`).
 850         ///
 851         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
 852         pub fn set_optional_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
 853                 self.set_custom_bit(bit + (1 - (bit % 2)))
 854         }
 855
 856         fn set_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
 857                 if bit < 256 {
 858                         return Err(());
 859                 }
 860                 self.set_bit(bit, true)
 861         }
 862
 863         fn set_bit(&mut self, bit: usize, custom: bool) -> Result<(), ()> {
 864                 let byte_offset = bit / 8;
 865                 let mask = 1 << (bit - 8 * byte_offset);
 866                 if byte_offset < T::KNOWN_FEATURE_MASK.len() && custom {
 867                         if (T::KNOWN_FEATURE_MASK[byte_offset] & mask) != 0 {
 868                                 return Err(());
 869                         }
 870                 }
 871
 872                 if self.flags.len() <= byte_offset {
 873                         self.flags.resize(byte_offset + 1, 0u8);
 874                 }
 875
 876                 self.flags[byte_offset] |= mask;
 877
 878                 Ok(())
 879         }
 880 }
 881
 882 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 883         #[cfg(test)]
 884         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
 885                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
 886                 self
 887         }
 888 }
 889
 890 impl<T: sealed::ShutdownAnySegwit> Features<T> {
 891         #[cfg(test)]
 892         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
 893                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
 894                 self
 895         }
 896 }
 897
 898 impl<T: sealed::Wumbo> Features<T> {
 899         #[cfg(test)]
 900         pub(crate) fn clear_wumbo(mut self) -> Self {
 901                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
 902                 self
 903         }
 904 }
 905
 906 impl<T: sealed::SCIDPrivacy> Features<T> {
 907         pub(crate) fn clear_scid_privacy(&mut self) {
 908                 <T as sealed::SCIDPrivacy>::clear_bits(&mut self.flags);
 909         }
 910 }
 911
 912 impl<T: sealed::AnchorsZeroFeeHtlcTx> Features<T> {
 913         pub(crate) fn clear_anchors_zero_fee_htlc_tx(&mut self) {
 914                 <T as sealed::AnchorsZeroFeeHtlcTx>::clear_bits(&mut self.flags);
 915         }
 916 }
 917
 918 #[cfg(test)]
 919 impl<T: sealed::UnknownFeature> Features<T> {
 920         pub(crate) fn unknown() -> Self {
 921                 let mut features = Self::empty();
 922                 features.set_unknown_feature_required();
 923                 features
 924         }
 925 }
 926
 927 macro_rules! impl_feature_len_prefixed_write {
 928         ($features: ident) => {
 929                 impl Writeable for $features {
 930                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 931                                 (self.flags.len() as u16).write(w)?;
 932                                 self.write_be(w)
 933                         }
 934                 }
 935                 impl Readable for $features {
 936                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 937                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
 938                         }
 939                 }
 940         }
 941 }
 942 impl_feature_len_prefixed_write!(InitFeatures);
 943 impl_feature_len_prefixed_write!(ChannelFeatures);
 944 impl_feature_len_prefixed_write!(NodeFeatures);
 945 impl_feature_len_prefixed_write!(Bolt11InvoiceFeatures);
 946 impl_feature_len_prefixed_write!(Bolt12InvoiceFeatures);
 947 impl_feature_len_prefixed_write!(BlindedHopFeatures);
 948
 949 // Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
 950 macro_rules! impl_feature_tlv_write {
 951         ($features: ident) => {
 952                 impl Writeable for $features {
 953                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 954                                 WithoutLength(self).write(w)
 955                         }
 956                 }
 957                 impl Readable for $features {
 958                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 959                                 Ok(WithoutLength::<Self>::read(r)?.0)
 960                         }
 961                 }
 962         }
 963 }
 964
 965 impl_feature_tlv_write!(ChannelTypeFeatures);
 966
 967 // Some features may appear both in a TLV record and as part of a TLV subtype sequence. The latter
 968 // requires a length but the former does not.
 969
 970 impl<T: sealed::Context> Writeable for WithoutLength<&Features<T>> {
 971         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 972                 self.0.write_be(w)
 973         }
 974 }
 975
 976 impl<T: sealed::Context> Readable for WithoutLength<Features<T>> {
 977         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 978                 let v = io_extras::read_to_end(r)?;
 979                 Ok(WithoutLength(Features::<T>::from_be_bytes(v)))
 980         }
 981 }
 982
 983 #[cfg(test)]
 984 mod tests {
 985         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, Bolt11InvoiceFeatures, NodeFeatures, OfferFeatures, sealed};
 986         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
 987         use crate::util::ser::{Readable, WithoutLength, Writeable};
 988
 989         #[test]
 990         fn sanity_test_unknown_bits() {
 991                 let features = ChannelFeatures::empty();
 992                 assert!(!features.requires_unknown_bits());
 993                 assert!(!features.supports_unknown_bits());
 994
 995                 let mut features = ChannelFeatures::empty();
 996                 features.set_unknown_feature_required();
 997                 assert!(features.requires_unknown_bits());
 998                 assert!(features.supports_unknown_bits());
 999
1000                 let mut features = ChannelFeatures::empty();
1001                 features.set_unknown_feature_optional();
1002                 assert!(!features.requires_unknown_bits());
1003                 assert!(features.supports_unknown_bits());
1004         }
1005
1006         #[test]
1007         fn requires_unknown_bits_from() {
1008                 let mut features1 = InitFeatures::empty();
1009                 let mut features2 = InitFeatures::empty();
1010                 assert!(!features1.requires_unknown_bits_from(&features2));
1011                 assert!(!features2.requires_unknown_bits_from(&features1));
1012
1013                 features1.set_data_loss_protect_required();
1014                 assert!(features1.requires_unknown_bits_from(&features2));
1015                 assert!(!features2.requires_unknown_bits_from(&features1));
1016
1017                 features2.set_data_loss_protect_optional();
1018                 assert!(!features1.requires_unknown_bits_from(&features2));
1019                 assert!(!features2.requires_unknown_bits_from(&features1));
1020
1021                 features2.set_gossip_queries_required();
1022                 assert!(!features1.requires_unknown_bits_from(&features2));
1023                 assert!(features2.requires_unknown_bits_from(&features1));
1024
1025                 features1.set_gossip_queries_optional();
1026                 assert!(!features1.requires_unknown_bits_from(&features2));
1027                 assert!(!features2.requires_unknown_bits_from(&features1));
1028
1029                 features1.set_variable_length_onion_required();
1030                 assert!(features1.requires_unknown_bits_from(&features2));
1031                 assert!(!features2.requires_unknown_bits_from(&features1));
1032
1033                 features2.set_variable_length_onion_optional();
1034                 assert!(!features1.requires_unknown_bits_from(&features2));
1035                 assert!(!features2.requires_unknown_bits_from(&features1));
1036
1037                 features1.set_basic_mpp_required();
1038                 features2.set_wumbo_required();
1039                 assert!(features1.requires_unknown_bits_from(&features2));
1040                 assert!(features2.requires_unknown_bits_from(&features1));
1041         }
1042
1043         #[test]
1044         fn convert_to_context_with_relevant_flags() {
1045                 let mut init_features = InitFeatures::empty();
1046                 // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
1047                 // converted as it's only relevant in an init context).
1048                 init_features.set_initial_routing_sync_required();
1049                 init_features.set_data_loss_protect_required();
1050                 init_features.set_variable_length_onion_required();
1051                 init_features.set_static_remote_key_required();
1052                 init_features.set_payment_secret_required();
1053                 init_features.set_basic_mpp_optional();
1054                 init_features.set_wumbo_optional();
1055                 init_features.set_anchors_zero_fee_htlc_tx_optional();
1056                 init_features.set_shutdown_any_segwit_optional();
1057                 init_features.set_onion_messages_optional();
1058                 init_features.set_channel_type_optional();
1059                 init_features.set_scid_privacy_optional();
1060                 init_features.set_zero_conf_optional();
1061
1062                 assert!(init_features.initial_routing_sync());
1063                 assert!(!init_features.supports_upfront_shutdown_script());
1064                 assert!(!init_features.supports_gossip_queries());
1065
1066                 let node_features: NodeFeatures = init_features.to_context();
1067                 {
1068                         // Check that the flags are as expected:
1069                         // - option_data_loss_protect (req)
1070                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
1071                         // - basic_mpp | wumbo | anchors_zero_fee_htlc_tx
1072                         // - opt_shutdown_anysegwit
1073                         // - onion_messages
1074                         // - option_channel_type | option_scid_alias
1075                         // - option_zeroconf
1076                         assert_eq!(node_features.flags.len(), 7);
1077                         assert_eq!(node_features.flags[0], 0b00000001);
1078                         assert_eq!(node_features.flags[1], 0b01010001);
1079                         assert_eq!(node_features.flags[2], 0b10001010);
1080                         assert_eq!(node_features.flags[3], 0b00001000);
1081                         assert_eq!(node_features.flags[4], 0b10000000);
1082                         assert_eq!(node_features.flags[5], 0b10100000);
1083                         assert_eq!(node_features.flags[6], 0b00001000);
1084                 }
1085
1086                 // Check that cleared flags are kept blank when converting back:
1087                 // - initial_routing_sync was not applicable to NodeContext
1088                 // - upfront_shutdown_script was cleared before converting
1089                 // - gossip_queries was cleared before converting
1090                 let features: InitFeatures = node_features.to_context_internal();
1091                 assert!(!features.initial_routing_sync());
1092                 assert!(!features.supports_upfront_shutdown_script());
1093                 assert!(!init_features.supports_gossip_queries());
1094         }
1095
1096         #[test]
1097         fn convert_to_context_with_unknown_flags() {
1098                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1099                 assert!(<sealed::ChannelContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
1100                         <sealed::Bolt11InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
1101                 let mut channel_features = ChannelFeatures::empty();
1102                 channel_features.set_unknown_feature_optional();
1103                 assert!(channel_features.supports_unknown_bits());
1104                 let invoice_features: Bolt11InvoiceFeatures = channel_features.to_context_internal();
1105                 assert!(!invoice_features.supports_unknown_bits());
1106         }
1107
1108         #[test]
1109         fn set_feature_bits() {
1110                 let mut features = Bolt11InvoiceFeatures::empty();
1111                 features.set_basic_mpp_optional();
1112                 features.set_payment_secret_required();
1113                 assert!(features.supports_basic_mpp());
1114                 assert!(!features.requires_basic_mpp());
1115                 assert!(features.requires_payment_secret());
1116                 assert!(features.supports_payment_secret());
1117
1118                 // Set flags manually
1119                 let mut features = NodeFeatures::empty();
1120                 assert!(features.set_optional_feature_bit(55).is_ok());
1121                 assert!(features.supports_keysend());
1122                 assert!(features.set_optional_feature_bit(255).is_ok());
1123                 assert!(features.set_required_feature_bit(256).is_err());
1124         }
1125
1126         #[test]
1127         fn set_custom_bits() {
1128                 let mut features = Bolt11InvoiceFeatures::empty();
1129                 features.set_variable_length_onion_optional();
1130                 assert_eq!(features.flags[1], 0b00000010);
1131
1132                 assert!(features.set_optional_custom_bit(255).is_err());
1133                 assert!(features.set_required_custom_bit(256).is_ok());
1134                 assert!(features.set_required_custom_bit(258).is_ok());
1135                 assert_eq!(features.flags[31], 0b00000000);
1136                 assert_eq!(features.flags[32], 0b00000101);
1137
1138                 let known_bit = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::EVEN_BIT;
1139                 let byte_offset = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::BYTE_OFFSET;
1140                 assert_eq!(byte_offset, 1);
1141                 assert_eq!(features.flags[byte_offset], 0b00000010);
1142                 assert!(features.set_required_custom_bit(known_bit).is_err());
1143                 assert_eq!(features.flags[byte_offset], 0b00000010);
1144
1145                 let mut features = Bolt11InvoiceFeatures::empty();
1146                 assert!(features.set_optional_custom_bit(256).is_ok());
1147                 assert!(features.set_optional_custom_bit(259).is_ok());
1148                 assert_eq!(features.flags[32], 0b00001010);
1149
1150                 let mut features = Bolt11InvoiceFeatures::empty();
1151                 assert!(features.set_required_custom_bit(257).is_ok());
1152                 assert!(features.set_required_custom_bit(258).is_ok());
1153                 assert_eq!(features.flags[32], 0b00000101);
1154         }
1155
1156         #[test]
1157         fn encodes_features_without_length() {
1158                 let features = OfferFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1159                 assert_eq!(features.flags.len(), 8);
1160
1161                 let mut serialized_features = Vec::new();
1162                 WithoutLength(&features).write(&mut serialized_features).unwrap();
1163                 assert_eq!(serialized_features.len(), 8);
1164
1165                 let deserialized_features =
1166                         WithoutLength::<OfferFeatures>::read(&mut &serialized_features[..]).unwrap().0;
1167                 assert_eq!(features, deserialized_features);
1168         }
1169
1170         #[test]
1171         fn invoice_features_encoding() {
1172                 let features_as_u5s = vec![
1173                         u5::try_from_u8(6).unwrap(),
1174                         u5::try_from_u8(10).unwrap(),
1175                         u5::try_from_u8(25).unwrap(),
1176                         u5::try_from_u8(1).unwrap(),
1177                         u5::try_from_u8(10).unwrap(),
1178                         u5::try_from_u8(0).unwrap(),
1179                         u5::try_from_u8(20).unwrap(),
1180                         u5::try_from_u8(2).unwrap(),
1181                         u5::try_from_u8(0).unwrap(),
1182                         u5::try_from_u8(6).unwrap(),
1183                         u5::try_from_u8(0).unwrap(),
1184                         u5::try_from_u8(16).unwrap(),
1185                         u5::try_from_u8(1).unwrap(),
1186                 ];
1187                 let features = Bolt11InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1188
1189                 // Test length calculation.
1190                 assert_eq!(features.base32_len(), 13);
1191
1192                 // Test serialization.
1193                 let features_serialized = features.to_base32();
1194                 assert_eq!(features_as_u5s, features_serialized);
1195
1196                 // Test deserialization.
1197                 let features_deserialized = Bolt11InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1198                 assert_eq!(features, features_deserialized);
1199         }
1200
1201         #[test]
1202         fn test_channel_type_mapping() {
1203                 // If we map an Bolt11InvoiceFeatures with StaticRemoteKey optional, it should map into a
1204                 // required-StaticRemoteKey ChannelTypeFeatures.
1205                 let mut init_features = InitFeatures::empty();
1206                 init_features.set_static_remote_key_optional();
1207                 let converted_features = ChannelTypeFeatures::from_init(&init_features);
1208                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1209                 assert!(!converted_features.supports_any_optional_bits());
1210                 assert!(converted_features.requires_static_remote_key());
1211         }
1212 }