_ 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 //! - `AnchorsZeroFeeHtlcTx` - requires/supports that commitment transactions include anchor outputs
  45 //!     and HTLC transactions are pre-signed with zero fee (see
  46 //!     [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more
  47 //!     information).
  48 //! - `RouteBlinding` - requires/supports that a node can relay payments over blinded paths
  49 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md#route-blinding) for more information).
  50 //! - `ShutdownAnySegwit` - requires/supports that future segwit versions are allowed in `shutdown`
  51 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  52 //! - `OnionMessages` - requires/supports forwarding onion messages
  53 //!     (see [BOLT-7](https://github.com/lightning/bolts/pull/759/files) for more information).
  54 //     TODO: update link
  55 //! - `ChannelType` - node supports the channel_type field in open/accept
  56 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  57 //! - `SCIDPrivacy` - supply channel aliases for routing
  58 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
  59 //! - `PaymentMetadata` - include additional data in invoices which is passed to recipients in the
  60 //!      onion.
  61 //!      (see [BOLT-11](https://github.com/lightning/bolts/blob/master/11-payment-encoding.md) for
  62 //!      more).
  63 //! - `ZeroConf` - supports accepting HTLCs and using channels prior to funding confirmation
  64 //!      (see
  65 //!      [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-channel_ready-message)
  66 //!      for more info).
  67 //! - `Keysend` - send funds to a node without an invoice
  68 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
  69 //! - `Trampoline` - supports receiving and forwarding Trampoline payments
  70 //!     (see the [`Trampoline` feature proposal](https://github.com/lightning/bolts/pull/836) for more information).
  71 //!
  72 //! LDK knows about the following features, but does not support them:
  73 //! - `AnchorsNonzeroFeeHtlcTx` - the initial version of anchor outputs, which was later found to be
  74 //!     vulnerable (see this
  75 //!     [mailing list post](https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-September/002796.html)
  76 //!     for more information).
  77 //!
  78 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
  79 //! [messages]: crate::ln::msgs
  80
  81 #[allow(unused_imports)]
  82 use crate::prelude::*;
  83
  84 use crate::{io, io_extras};
  85 use core::{cmp, fmt};
  86 use core::borrow::Borrow;
  87 use core::hash::{Hash, Hasher};
  88 use core::marker::PhantomData;
  89
  90 use bitcoin::bech32;
  91 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
  92 use crate::ln::msgs::DecodeError;
  93 use crate::util::ser::{Readable, WithoutLength, Writeable, Writer};
  94
  95 mod sealed {
  96         #[allow(unused_imports)]
  97         use crate::prelude::*;
  98         use crate::ln::features::Features;
  99
 100         /// The context in which [`Features`] are applicable. Defines which features are known to the
 101         /// implementation, though specification of them as required or optional is up to the code
 102         /// constructing a features object.
 103         pub trait Context {
 104                 /// Bitmask for selecting features that are known to the implementation.
 105                 const KNOWN_FEATURE_MASK: &'static [u8];
 106         }
 107
 108         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
 109         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
 110         /// feature identifiers.
 111         macro_rules! define_context {
 112                 ($context: ident, [$( $( $known_feature: ident )|*, )*]) => {
 113                         #[derive(Eq, PartialEq)]
 114                         pub struct $context {}
 115
 116                         impl Context for $context {
 117                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
 118                                         $(
 119                                                 0b00_00_00_00 $(|
 120                                                         <Self as $known_feature>::REQUIRED_MASK |
 121                                                         <Self as $known_feature>::OPTIONAL_MASK)*,
 122                                         )*
 123                                 ];
 124                         }
 125
 126                         impl alloc::fmt::Display for Features<$context> {
 127                                 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
 128                                         $(
 129                                                 $(
 130                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($known_feature),
 131                                                                 if <$context as $known_feature>::requires_feature(&self.flags) { "required" }
 132                                                                 else if <$context as $known_feature>::supports_feature(&self.flags) { "supported" }
 133                                                                 else { "not supported" }))?;
 134                                                 )*
 135                                                 {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
 136                                         )*
 137                                         fmt.write_fmt(format_args!("unknown flags: {}",
 138                                                 if self.requires_unknown_bits() { "required" }
 139                                                 else if self.supports_unknown_bits() { "supported" } else { "none" }))
 140                                 }
 141                         }
 142                 };
 143         }
 144
 145         define_context!(InitContext, [
 146                 // Byte 0
 147                 DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
 148                 // Byte 1
 149                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 150                 // Byte 2
 151                 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
 152                 // Byte 3
 153                 RouteBlinding | ShutdownAnySegwit | Taproot,
 154                 // Byte 4
 155                 OnionMessages,
 156                 // Byte 5
 157                 ChannelType | SCIDPrivacy,
 158                 // Byte 6
 159                 ZeroConf,
 160                 // Byte 7
 161                 Trampoline,
 162         ]);
 163         define_context!(NodeContext, [
 164                 // Byte 0
 165                 DataLossProtect | UpfrontShutdownScript | GossipQueries,
 166                 // Byte 1
 167                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
 168                 // Byte 2
 169                 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
 170                 // Byte 3
 171                 RouteBlinding | ShutdownAnySegwit | Taproot,
 172                 // Byte 4
 173                 OnionMessages,
 174                 // Byte 5
 175                 ChannelType | SCIDPrivacy,
 176                 // Byte 6
 177                 ZeroConf | Keysend,
 178                 // Byte 7
 179                 Trampoline,
 180         ]);
 181         define_context!(ChannelContext, []);
 182         define_context!(Bolt11InvoiceContext, [
 183                 // Byte 0
 184                 ,
 185                 // Byte 1
 186                 VariableLengthOnion | PaymentSecret,
 187                 // Byte 2
 188                 BasicMPP,
 189                 // Byte 3
 190                 ,
 191                 // Byte 4
 192                 ,
 193                 // Byte 5
 194                 ,
 195                 // Byte 6
 196                 PaymentMetadata,
 197                 // Byte 7
 198                 Trampoline,
 199         ]);
 200         define_context!(OfferContext, []);
 201         define_context!(InvoiceRequestContext, []);
 202         define_context!(Bolt12InvoiceContext, [
 203                 // Byte 0
 204                 ,
 205                 // Byte 1
 206                 ,
 207                 // Byte 2
 208                 BasicMPP,
 209         ]);
 210         define_context!(BlindedHopContext, []);
 211         // This isn't a "real" feature context, and is only used in the channel_type field in an
 212         // `OpenChannel` message.
 213         define_context!(ChannelTypeContext, [
 214                 // Byte 0
 215                 ,
 216                 // Byte 1
 217                 StaticRemoteKey,
 218                 // Byte 2
 219                 AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
 220                 // Byte 3
 221                 Taproot,
 222                 // Byte 4
 223                 ,
 224                 // Byte 5
 225                 SCIDPrivacy,
 226                 // Byte 6
 227                 ZeroConf,
 228         ]);
 229
 230         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
 231         /// useful for manipulating feature flags.
 232         macro_rules! define_feature {
 233                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 234                  $required_setter: ident, $supported_getter: ident) => {
 235                         #[doc = $doc]
 236                         ///
 237                         /// See [BOLT #9] for details.
 238                         ///
 239                         /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
 240                         pub trait $feature: Context {
 241                                 /// The bit used to signify that the feature is required.
 242                                 const EVEN_BIT: usize = $odd_bit - 1;
 243
 244                                 /// The bit used to signify that the feature is optional.
 245                                 const ODD_BIT: usize = $odd_bit;
 246
 247                                 /// Assertion that [`EVEN_BIT`] is actually even.
 248                                 ///
 249                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
 250                                 const ASSERT_EVEN_BIT_PARITY: usize;
 251
 252                                 /// Assertion that [`ODD_BIT`] is actually odd.
 253                                 ///
 254                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
 255                                 const ASSERT_ODD_BIT_PARITY: usize;
 256
 257                                 /// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
 258                                 ///
 259                                 /// [`KNOWN_FEATURE_MASK`]: Context::KNOWN_FEATURE_MASK
 260                                 #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
 261                                 const ASSERT_BITS_IN_MASK: u8;
 262
 263                                 /// The byte where the feature is set.
 264                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
 265
 266                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
 267                                 ///
 268                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 269                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
 270
 271                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
 272                                 ///
 273                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
 274                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
 275
 276                                 /// Returns whether the feature is required by the given flags.
 277                                 #[inline]
 278                                 fn requires_feature(flags: &Vec<u8>) -> bool {
 279                                         flags.len() > Self::BYTE_OFFSET &&
 280                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
 281                                 }
 282
 283                                 /// Returns whether the feature is supported by the given flags.
 284                                 #[inline]
 285                                 fn supports_feature(flags: &Vec<u8>) -> bool {
 286                                         flags.len() > Self::BYTE_OFFSET &&
 287                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
 288                                 }
 289
 290                                 /// Sets the feature's required (even) bit in the given flags.
 291                                 #[inline]
 292                                 fn set_required_bit(flags: &mut Vec<u8>) {
 293                                         if flags.len() <= Self::BYTE_OFFSET {
 294                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 295                                         }
 296
 297                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
 298                                         flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 299                                 }
 300
 301                                 /// Sets the feature's optional (odd) bit in the given flags.
 302                                 #[inline]
 303                                 fn set_optional_bit(flags: &mut Vec<u8>) {
 304                                         if flags.len() <= Self::BYTE_OFFSET {
 305                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
 306                                         }
 307
 308                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
 309                                 }
 310
 311                                 /// Clears the feature's required (even) and optional (odd) bits from the given
 312                                 /// flags.
 313                                 #[inline]
 314                                 fn clear_bits(flags: &mut Vec<u8>) {
 315                                         if flags.len() > Self::BYTE_OFFSET {
 316                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
 317                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
 318                                         }
 319
 320                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
 321                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
 322                                         flags.resize(size, 0u8);
 323                                 }
 324                         }
 325
 326                         impl <T: $feature> Features<T> {
 327                                 /// Set this feature as optional.
 328                                 pub fn $optional_setter(&mut self) {
 329                                         <T as $feature>::set_optional_bit(&mut self.flags);
 330                                 }
 331
 332                                 /// Set this feature as required.
 333                                 pub fn $required_setter(&mut self) {
 334                                         <T as $feature>::set_required_bit(&mut self.flags);
 335                                 }
 336
 337                                 /// Checks if this feature is supported.
 338                                 pub fn $supported_getter(&self) -> bool {
 339                                         <T as $feature>::supports_feature(&self.flags)
 340                                 }
 341                         }
 342
 343                         $(
 344                                 impl $feature for $context {
 345                                         // EVEN_BIT % 2 == 0
 346                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
 347
 348                                         // ODD_BIT % 2 == 1
 349                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
 350
 351                                         // (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
 352                                         #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
 353                                         const ASSERT_BITS_IN_MASK: u8 =
 354                                                 ((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
 355                                                  >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
 356                                 }
 357                         )*
 358                 };
 359                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
 360                  $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
 361                         define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
 362                         impl <T: $feature> Features<T> {
 363                                 /// Checks if this feature is required.
 364                                 pub fn $required_getter(&self) -> bool {
 365                                         <T as $feature>::requires_feature(&self.flags)
 366                                 }
 367                         }
 368                 }
 369         }
 370
 371         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
 372                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
 373                 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
 374         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
 375         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
 376                 set_initial_routing_sync_optional, set_initial_routing_sync_required,
 377                 initial_routing_sync);
 378         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
 379                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
 380                 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
 381                 requires_upfront_shutdown_script);
 382         define_feature!(7, GossipQueries, [InitContext, NodeContext],
 383                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
 384                 supports_gossip_queries, requires_gossip_queries);
 385         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, Bolt11InvoiceContext],
 386                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
 387                 set_variable_length_onion_required, supports_variable_length_onion,
 388                 requires_variable_length_onion);
 389         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
 390                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
 391                 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
 392         define_feature!(15, PaymentSecret, [InitContext, NodeContext, Bolt11InvoiceContext],
 393                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
 394                 supports_payment_secret, requires_payment_secret);
 395         define_feature!(17, BasicMPP, [InitContext, NodeContext, Bolt11InvoiceContext, Bolt12InvoiceContext],
 396                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
 397                 supports_basic_mpp, requires_basic_mpp);
 398         define_feature!(19, Wumbo, [InitContext, NodeContext],
 399                 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
 400                 supports_wumbo, requires_wumbo);
 401         define_feature!(21, AnchorsNonzeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
 402                 "Feature flags for `option_anchors_nonzero_fee_htlc_tx`.", set_anchors_nonzero_fee_htlc_tx_optional,
 403                 set_anchors_nonzero_fee_htlc_tx_required, supports_anchors_nonzero_fee_htlc_tx, requires_anchors_nonzero_fee_htlc_tx);
 404         define_feature!(23, AnchorsZeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
 405                 "Feature flags for `option_anchors_zero_fee_htlc_tx`.", set_anchors_zero_fee_htlc_tx_optional,
 406                 set_anchors_zero_fee_htlc_tx_required, supports_anchors_zero_fee_htlc_tx, requires_anchors_zero_fee_htlc_tx);
 407         define_feature!(25, RouteBlinding, [InitContext, NodeContext],
 408                 "Feature flags for `option_route_blinding`.", set_route_blinding_optional,
 409                 set_route_blinding_required, supports_route_blinding, requires_route_blinding);
 410         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
 411                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
 412                 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
 413         define_feature!(31, Taproot, [InitContext, NodeContext, ChannelTypeContext],
 414                 "Feature flags for `option_taproot`.", set_taproot_optional,
 415                 set_taproot_required, supports_taproot, requires_taproot);
 416         define_feature!(39, OnionMessages, [InitContext, NodeContext],
 417                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
 418                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
 419         define_feature!(45, ChannelType, [InitContext, NodeContext],
 420                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
 421                 set_channel_type_required, supports_channel_type, requires_channel_type);
 422         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
 423                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
 424                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
 425         define_feature!(49, PaymentMetadata, [Bolt11InvoiceContext],
 426                 "Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
 427                 set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
 428         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
 429                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
 430                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
 431         define_feature!(55, Keysend, [NodeContext],
 432                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
 433                 supports_keysend, requires_keysend);
 434         define_feature!(57, Trampoline, [InitContext, NodeContext, Bolt11InvoiceContext],
 435                 "Feature flags for Trampoline routing.", set_trampoline_routing_optional, set_trampoline_routing_required,
 436                 supports_trampoline_routing, requires_trampoline_routing);
 437         // Note: update the module-level docs when a new feature bit is added!
 438
 439         #[cfg(test)]
 440         define_feature!(123456789, UnknownFeature,
 441                 [NodeContext, ChannelContext, Bolt11InvoiceContext, OfferContext, InvoiceRequestContext, Bolt12InvoiceContext, BlindedHopContext],
 442                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
 443                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
 444 }
 445
 446 /// Tracks the set of features which a node implements, templated by the context in which it
 447 /// appears.
 448 ///
 449 /// This is not exported to bindings users as we map the concrete feature types below directly instead
 450 #[derive(Eq)]
 451 pub struct Features<T: sealed::Context> {
 452         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
 453         flags: Vec<u8>,
 454         mark: PhantomData<T>,
 455 }
 456
 457 impl<T: sealed::Context, Rhs: Borrow<Self>> core::ops::BitOrAssign<Rhs> for Features<T> {
 458         fn bitor_assign(&mut self, rhs: Rhs) {
 459                 let total_feature_len = cmp::max(self.flags.len(), rhs.borrow().flags.len());
 460                 self.flags.resize(total_feature_len, 0u8);
 461                 for (byte, rhs_byte) in self.flags.iter_mut().zip(rhs.borrow().flags.iter()) {
 462                         *byte |= *rhs_byte;
 463                 }
 464         }
 465 }
 466
 467 impl<T: sealed::Context> core::ops::BitOr for Features<T> {
 468         type Output = Self;
 469
 470         fn bitor(mut self, o: Self) -> Self {
 471                 self |= o;
 472                 self
 473         }
 474 }
 475
 476 impl<T: sealed::Context> Clone for Features<T> {
 477         fn clone(&self) -> Self {
 478                 Self {
 479                         flags: self.flags.clone(),
 480                         mark: PhantomData,
 481                 }
 482         }
 483 }
 484 impl<T: sealed::Context> Hash for Features<T> {
 485         fn hash<H: Hasher>(&self, hasher: &mut H) {
 486                 let mut nonzero_flags = &self.flags[..];
 487                 while nonzero_flags.last() == Some(&0) {
 488                         nonzero_flags = &nonzero_flags[..nonzero_flags.len() - 1];
 489                 }
 490                 nonzero_flags.hash(hasher);
 491         }
 492 }
 493 impl<T: sealed::Context> PartialEq for Features<T> {
 494         fn eq(&self, o: &Self) -> bool {
 495                 let mut o_iter = o.flags.iter();
 496                 let mut self_iter = self.flags.iter();
 497                 loop {
 498                         match (o_iter.next(), self_iter.next()) {
 499                                 (Some(o), Some(us)) => if o != us { return false },
 500                                 (Some(b), None) | (None, Some(b)) => if *b != 0 { return false },
 501                                 (None, None) => return true,
 502                         }
 503                 }
 504         }
 505 }
 506 impl<T: sealed::Context> PartialOrd for Features<T> {
 507         fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
 508                 self.flags.partial_cmp(&other.flags)
 509         }
 510 }
 511 impl<T: sealed::Context + Eq> Ord for Features<T> {
 512         fn cmp(&self, other: &Self) -> cmp::Ordering {
 513                 self.flags.cmp(&other.flags)
 514         }
 515 }
 516 impl<T: sealed::Context> fmt::Debug for Features<T> {
 517         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 518                 self.flags.fmt(fmt)
 519         }
 520 }
 521
 522 /// Features used within an `init` message.
 523 pub type InitFeatures = Features<sealed::InitContext>;
 524 /// Features used within a `node_announcement` message.
 525 pub type NodeFeatures = Features<sealed::NodeContext>;
 526 /// Features used within a `channel_announcement` message.
 527 pub type ChannelFeatures = Features<sealed::ChannelContext>;
 528 /// Features used within an invoice.
 529 pub type Bolt11InvoiceFeatures = Features<sealed::Bolt11InvoiceContext>;
 530 /// Features used within an `offer`.
 531 pub type OfferFeatures = Features<sealed::OfferContext>;
 532 /// Features used within an `invoice_request`.
 533 pub type InvoiceRequestFeatures = Features<sealed::InvoiceRequestContext>;
 534 /// Features used within an `invoice`.
 535 pub type Bolt12InvoiceFeatures = Features<sealed::Bolt12InvoiceContext>;
 536 /// Features used within BOLT 4 encrypted_data_tlv and BOLT 12 blinded_payinfo
 537 pub type BlindedHopFeatures = Features<sealed::BlindedHopContext>;
 538
 539 /// Features used within the channel_type field in an OpenChannel message.
 540 ///
 541 /// A channel is always of some known "type", describing the transaction formats used and the exact
 542 /// semantics of our interaction with our peer.
 543 ///
 544 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
 545 /// the counterparty, only required features are allowed here.
 546 ///
 547 /// This is serialized differently from other feature types - it is not prefixed by a length, and
 548 /// thus must only appear inside a TLV where its length is known in advance.
 549 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
 550
 551 impl InitFeatures {
 552         /// Writes all features present up to, and including, 13.
 553         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 554                 let len = cmp::min(2, self.flags.len());
 555                 (len as u16).write(w)?;
 556                 for i in (0..len).rev() {
 557                         if i == 0 {
 558                                 self.flags[i].write(w)?;
 559                         } else {
 560                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
 561                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
 562                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
 563                         }
 564                 }
 565                 Ok(())
 566         }
 567
 568         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
 569         /// are included in the result.
 570         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 571                 self.to_context_internal()
 572         }
 573 }
 574
 575 impl Bolt11InvoiceFeatures {
 576         /// Converts `Bolt11InvoiceFeatures` to `Features<C>`. Only known `Bolt11InvoiceFeatures` relevant to
 577         /// context `C` are included in the result.
 578         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 579                 self.to_context_internal()
 580         }
 581
 582         /// Getting a route for a keysend payment to a private node requires providing the payee's
 583         /// features (since they were not announced in a node announcement). However, keysend payments
 584         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
 585         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
 586         /// `Bolt11InvoiceFeatures` for [`find_route`].
 587         ///
 588         /// MPP keysend is not widely supported yet, so we parameterize support to allow the user to
 589         /// choose whether their router should find multi-part routes.
 590         ///
 591         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
 592         /// [`find_route`]: crate::routing::router::find_route
 593         pub(crate) fn for_keysend(allow_mpp: bool) -> Bolt11InvoiceFeatures {
 594                 let mut res = Bolt11InvoiceFeatures::empty();
 595                 res.set_variable_length_onion_optional();
 596                 if allow_mpp {
 597                         res.set_basic_mpp_optional();
 598                 }
 599                 res
 600         }
 601 }
 602
 603 impl Bolt12InvoiceFeatures {
 604         /// Converts [`Bolt12InvoiceFeatures`] to [`Features<C>`]. Only known [`Bolt12InvoiceFeatures`]
 605         /// relevant to context `C` are included in the result.
 606         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
 607                 self.to_context_internal()
 608         }
 609 }
 610
 611 impl ChannelTypeFeatures {
 612         // Maps the relevant `InitFeatures` to `ChannelTypeFeatures`. Any unknown features to
 613         // `ChannelTypeFeatures` are not included in the result.
 614         pub(crate) fn from_init(init: &InitFeatures) -> Self {
 615                 let mut ret = init.to_context_internal();
 616                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
 617                 // optional bits and then AND out the optional ones.
 618                 for byte in ret.flags.iter_mut() {
 619                         *byte |= (*byte & 0b10_10_10_10) >> 1;
 620                         *byte &= 0b01_01_01_01;
 621                 }
 622                 ret
 623         }
 624
 625         /// Constructs a ChannelTypeFeatures with only static_remotekey set
 626         pub(crate) fn only_static_remote_key() -> Self {
 627                 let mut ret = Self::empty();
 628                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
 629                 ret
 630         }
 631
 632         /// Constructs a ChannelTypeFeatures with anchors support
 633         pub(crate) fn anchors_zero_htlc_fee_and_dependencies() -> Self {
 634                 let mut ret = Self::empty();
 635                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
 636                 <sealed::ChannelTypeContext as sealed::AnchorsZeroFeeHtlcTx>::set_required_bit(&mut ret.flags);
 637                 ret
 638         }
 639 }
 640
 641 impl ToBase32 for Bolt11InvoiceFeatures {
 642         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
 643                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
 644                 // minus one before dividing
 645                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
 646                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
 647                 for (byte_idx, byte) in self.flags.iter().enumerate() {
 648                         let bit_pos_from_left_0_indexed = byte_idx * 8;
 649                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
 650                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
 651                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
 652                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
 653                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
 654                         if new_u5_idx > 0 {
 655                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
 656                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
 657                         }
 658                         if new_u5_idx > 1 {
 659                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
 660                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
 661                         }
 662                 }
 663                 // Trim the highest feature bits.
 664                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
 665                         res_u5s.remove(0);
 666                 }
 667                 writer.write(&res_u5s)
 668         }
 669 }
 670
 671 impl Base32Len for Bolt11InvoiceFeatures {
 672         fn base32_len(&self) -> usize {
 673                 self.to_base32().len()
 674         }
 675 }
 676
 677 impl FromBase32 for Bolt11InvoiceFeatures {
 678         type Err = bech32::Error;
 679
 680         fn from_base32(field_data: &[u5]) -> Result<Bolt11InvoiceFeatures, bech32::Error> {
 681                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
 682                 // minus one before dividing
 683                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
 684                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
 685                 for (u5_idx, chunk) in field_data.iter().enumerate() {
 686                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
 687                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
 688                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
 689                         let chunk_u16 = chunk.to_u8() as u16;
 690                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
 691                         if new_byte_idx != length_bytes - 1 {
 692                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
 693                         }
 694                 }
 695                 // Trim the highest feature bits.
 696                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
 697                         res_bytes.pop();
 698                 }
 699                 Ok(Bolt11InvoiceFeatures::from_le_bytes(res_bytes))
 700         }
 701 }
 702
 703 impl<T: sealed::Context> Features<T> {
 704         /// Create a blank Features with no features set
 705         pub fn empty() -> Self {
 706                 Features {
 707                         flags: Vec::new(),
 708                         mark: PhantomData,
 709                 }
 710         }
 711
 712         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
 713         /// included in the result.
 714         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
 715                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
 716                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
 717                 let mut flags = Vec::new();
 718                 for (i, byte) in self.flags.iter().enumerate() {
 719                         if i < from_byte_count && i < to_byte_count {
 720                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
 721                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
 722                                 flags.push(byte & from_known_features & to_known_features);
 723                         }
 724                 }
 725                 Features::<C> { flags, mark: PhantomData, }
 726         }
 727
 728         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
 729         /// most on-the-wire encodings.
 730         ///
 731         /// This is not exported to bindings users as we don't support export across multiple T
 732         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
 733                 Features {
 734                         flags,
 735                         mark: PhantomData,
 736                 }
 737         }
 738
 739         #[cfg(test)]
 740         /// Gets the underlying flags set, in LE.
 741         pub fn le_flags(&self) -> &Vec<u8> {
 742                 &self.flags
 743         }
 744
 745         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 746                 for f in self.flags.iter().rev() { // Swap back to big-endian
 747                         f.write(w)?;
 748                 }
 749                 Ok(())
 750         }
 751
 752         /// Create a [`Features`] given a set of flags, in big-endian. This is in byte order from
 753         /// most on-the-wire encodings.
 754         ///
 755         /// This is not exported to bindings users as we don't support export across multiple T
 756         pub fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
 757                 flags.reverse(); // Swap to little-endian
 758                 Self {
 759                         flags,
 760                         mark: PhantomData,
 761                 }
 762         }
 763
 764         pub(crate) fn supports_any_optional_bits(&self) -> bool {
 765                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
 766         }
 767
 768         /// Returns true if this `Features` object contains required features unknown by `other`.
 769         pub fn requires_unknown_bits_from(&self, other: &Self) -> bool {
 770                 // Bitwise AND-ing with all even bits set except for known features will select required
 771                 // unknown features.
 772                 self.flags.iter().enumerate().any(|(i, &byte)| {
 773                         const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
 774                         const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
 775                         let unknown_features = if i < other.flags.len() {
 776                                 // Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
 777                                 !(other.flags[i]
 778                                         | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
 779                                         | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
 780                         } else {
 781                                 0b11_11_11_11
 782                         };
 783                         (byte & (REQUIRED_FEATURES & unknown_features)) != 0
 784                 })
 785         }
 786
 787         /// Returns true if this `Features` object contains unknown feature flags which are set as
 788         /// "required".
 789         pub fn requires_unknown_bits(&self) -> bool {
 790                 // Bitwise AND-ing with all even bits set except for known features will select required
 791                 // unknown features.
 792                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 793                 self.flags.iter().enumerate().any(|(i, &byte)| {
 794                         let required_features = 0b01_01_01_01;
 795                         let unknown_features = if i < byte_count {
 796                                 !T::KNOWN_FEATURE_MASK[i]
 797                         } else {
 798                                 0b11_11_11_11
 799                         };
 800                         (byte & (required_features & unknown_features)) != 0
 801                 })
 802         }
 803
 804         pub(crate) fn supports_unknown_bits(&self) -> bool {
 805                 // Bitwise AND-ing with all even and odd bits set except for known features will select
 806                 // both required and optional unknown features.
 807                 let byte_count = T::KNOWN_FEATURE_MASK.len();
 808                 self.flags.iter().enumerate().any(|(i, &byte)| {
 809                         let unknown_features = if i < byte_count {
 810                                 !T::KNOWN_FEATURE_MASK[i]
 811                         } else {
 812                                 0b11_11_11_11
 813                         };
 814                         (byte & unknown_features) != 0
 815                 })
 816         }
 817
 818         // Returns true if the features within `self` are a subset of the features within `other`.
 819         pub(crate) fn is_subset(&self, other: &Self) -> bool {
 820                 for (idx, byte) in self.flags.iter().enumerate() {
 821                         if let Some(other_byte) = other.flags.get(idx) {
 822                                 if byte & other_byte != *byte {
 823                                         // `self` has bits set that `other` doesn't.
 824                                         return false;
 825                                 }
 826                         } else {
 827                                 if *byte > 0 {
 828                                         // `self` has a non-zero byte that `other` doesn't.
 829                                         return false;
 830                                 }
 831                         }
 832                 }
 833                 true
 834         }
 835
 836         /// Sets a required feature bit. Errors if `bit` is outside the feature range as defined
 837         /// by [BOLT 9].
 838         ///
 839         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
 840         /// be set instead (i.e., `bit - 1`).
 841         ///
 842         /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
 843         pub fn set_required_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
 844                 self.set_feature_bit(bit - (bit % 2))
 845         }
 846
 847         /// Sets an optional feature bit. Errors if `bit` is outside the feature range as defined
 848         /// by [BOLT 9].
 849         ///
 850         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
 851         /// set instead (i.e., `bit + 1`).
 852         ///
 853         /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
 854         pub fn set_optional_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
 855                 self.set_feature_bit(bit + (1 - (bit % 2)))
 856         }
 857
 858         fn set_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
 859                 if bit > 255 {
 860                         return Err(());
 861                 }
 862                 self.set_bit(bit, false)
 863         }
 864
 865         /// Sets a required custom feature bit. Errors if `bit` is outside the custom range as defined
 866         /// by [bLIP 2] or if it is a known `T` feature.
 867         ///
 868         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
 869         /// be set instead (i.e., `bit - 1`).
 870         ///
 871         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
 872         pub fn set_required_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
 873                 self.set_custom_bit(bit - (bit % 2))
 874         }
 875
 876         /// Sets an optional custom feature bit. Errors if `bit` is outside the custom range as defined
 877         /// by [bLIP 2] or if it is a known `T` feature.
 878         ///
 879         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
 880         /// set instead (i.e., `bit + 1`).
 881         ///
 882         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
 883         pub fn set_optional_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
 884                 self.set_custom_bit(bit + (1 - (bit % 2)))
 885         }
 886
 887         fn set_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
 888                 if bit < 256 {
 889                         return Err(());
 890                 }
 891                 self.set_bit(bit, true)
 892         }
 893
 894         fn set_bit(&mut self, bit: usize, custom: bool) -> Result<(), ()> {
 895                 let byte_offset = bit / 8;
 896                 let mask = 1 << (bit - 8 * byte_offset);
 897                 if byte_offset < T::KNOWN_FEATURE_MASK.len() && custom {
 898                         if (T::KNOWN_FEATURE_MASK[byte_offset] & mask) != 0 {
 899                                 return Err(());
 900                         }
 901                 }
 902
 903                 if self.flags.len() <= byte_offset {
 904                         self.flags.resize(byte_offset + 1, 0u8);
 905                 }
 906
 907                 self.flags[byte_offset] |= mask;
 908
 909                 Ok(())
 910         }
 911 }
 912
 913 impl<T: sealed::UpfrontShutdownScript> Features<T> {
 914         #[cfg(test)]
 915         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
 916                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
 917                 self
 918         }
 919 }
 920
 921 impl<T: sealed::ShutdownAnySegwit> Features<T> {
 922         #[cfg(test)]
 923         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
 924                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
 925                 self
 926         }
 927 }
 928
 929 impl<T: sealed::Wumbo> Features<T> {
 930         #[cfg(test)]
 931         pub(crate) fn clear_wumbo(mut self) -> Self {
 932                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
 933                 self
 934         }
 935 }
 936
 937 impl<T: sealed::SCIDPrivacy> Features<T> {
 938         pub(crate) fn clear_scid_privacy(&mut self) {
 939                 <T as sealed::SCIDPrivacy>::clear_bits(&mut self.flags);
 940         }
 941 }
 942
 943 impl<T: sealed::AnchorsZeroFeeHtlcTx> Features<T> {
 944         pub(crate) fn clear_anchors_zero_fee_htlc_tx(&mut self) {
 945                 <T as sealed::AnchorsZeroFeeHtlcTx>::clear_bits(&mut self.flags);
 946         }
 947 }
 948
 949 impl<T: sealed::RouteBlinding> Features<T> {
 950         #[cfg(test)]
 951         pub(crate) fn clear_route_blinding(&mut self) {
 952                 <T as sealed::RouteBlinding>::clear_bits(&mut self.flags);
 953         }
 954 }
 955
 956 #[cfg(test)]
 957 impl<T: sealed::UnknownFeature> Features<T> {
 958         pub(crate) fn unknown() -> Self {
 959                 let mut features = Self::empty();
 960                 features.set_unknown_feature_required();
 961                 features
 962         }
 963 }
 964
 965 macro_rules! impl_feature_len_prefixed_write {
 966         ($features: ident) => {
 967                 impl Writeable for $features {
 968                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 969                                 (self.flags.len() as u16).write(w)?;
 970                                 self.write_be(w)
 971                         }
 972                 }
 973                 impl Readable for $features {
 974                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 975                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
 976                         }
 977                 }
 978         }
 979 }
 980 impl_feature_len_prefixed_write!(InitFeatures);
 981 impl_feature_len_prefixed_write!(ChannelFeatures);
 982 impl_feature_len_prefixed_write!(NodeFeatures);
 983 impl_feature_len_prefixed_write!(Bolt11InvoiceFeatures);
 984 impl_feature_len_prefixed_write!(Bolt12InvoiceFeatures);
 985 impl_feature_len_prefixed_write!(BlindedHopFeatures);
 986
 987 // Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
 988 macro_rules! impl_feature_tlv_write {
 989         ($features: ident) => {
 990                 impl Writeable for $features {
 991                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 992                                 WithoutLength(self).write(w)
 993                         }
 994                 }
 995                 impl Readable for $features {
 996                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 997                                 Ok(WithoutLength::<Self>::read(r)?.0)
 998                         }
 999                 }
1000         }
1001 }
1002
1003 impl_feature_tlv_write!(ChannelTypeFeatures);
1004
1005 // Some features may appear both in a TLV record and as part of a TLV subtype sequence. The latter
1006 // requires a length but the former does not.
1007
1008 impl<T: sealed::Context> Writeable for WithoutLength<&Features<T>> {
1009         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1010                 self.0.write_be(w)
1011         }
1012 }
1013
1014 impl<T: sealed::Context> Readable for WithoutLength<Features<T>> {
1015         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
1016                 let v = io_extras::read_to_end(r)?;
1017                 Ok(WithoutLength(Features::<T>::from_be_bytes(v)))
1018         }
1019 }
1020
1021 #[cfg(test)]
1022 mod tests {
1023         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, Bolt11InvoiceFeatures, NodeFeatures, OfferFeatures, sealed};
1024         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
1025         use crate::util::ser::{Readable, WithoutLength, Writeable};
1026
1027         #[test]
1028         fn sanity_test_unknown_bits() {
1029                 let features = ChannelFeatures::empty();
1030                 assert!(!features.requires_unknown_bits());
1031                 assert!(!features.supports_unknown_bits());
1032
1033                 let mut features = ChannelFeatures::empty();
1034                 features.set_unknown_feature_required();
1035                 assert!(features.requires_unknown_bits());
1036                 assert!(features.supports_unknown_bits());
1037
1038                 let mut features = ChannelFeatures::empty();
1039                 features.set_unknown_feature_optional();
1040                 assert!(!features.requires_unknown_bits());
1041                 assert!(features.supports_unknown_bits());
1042         }
1043
1044         #[test]
1045         fn requires_unknown_bits_from() {
1046                 let mut features1 = InitFeatures::empty();
1047                 let mut features2 = InitFeatures::empty();
1048                 assert!(!features1.requires_unknown_bits_from(&features2));
1049                 assert!(!features2.requires_unknown_bits_from(&features1));
1050
1051                 features1.set_data_loss_protect_required();
1052                 assert!(features1.requires_unknown_bits_from(&features2));
1053                 assert!(!features2.requires_unknown_bits_from(&features1));
1054
1055                 features2.set_data_loss_protect_optional();
1056                 assert!(!features1.requires_unknown_bits_from(&features2));
1057                 assert!(!features2.requires_unknown_bits_from(&features1));
1058
1059                 features2.set_gossip_queries_required();
1060                 assert!(!features1.requires_unknown_bits_from(&features2));
1061                 assert!(features2.requires_unknown_bits_from(&features1));
1062
1063                 features1.set_gossip_queries_optional();
1064                 assert!(!features1.requires_unknown_bits_from(&features2));
1065                 assert!(!features2.requires_unknown_bits_from(&features1));
1066
1067                 features1.set_variable_length_onion_required();
1068                 assert!(features1.requires_unknown_bits_from(&features2));
1069                 assert!(!features2.requires_unknown_bits_from(&features1));
1070
1071                 features2.set_variable_length_onion_optional();
1072                 assert!(!features1.requires_unknown_bits_from(&features2));
1073                 assert!(!features2.requires_unknown_bits_from(&features1));
1074
1075                 features1.set_basic_mpp_required();
1076                 features2.set_wumbo_required();
1077                 assert!(features1.requires_unknown_bits_from(&features2));
1078                 assert!(features2.requires_unknown_bits_from(&features1));
1079         }
1080
1081         #[test]
1082         fn convert_to_context_with_relevant_flags() {
1083                 let mut init_features = InitFeatures::empty();
1084                 // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
1085                 // converted as it's only relevant in an init context).
1086                 init_features.set_initial_routing_sync_required();
1087                 init_features.set_data_loss_protect_required();
1088                 init_features.set_variable_length_onion_required();
1089                 init_features.set_static_remote_key_required();
1090                 init_features.set_payment_secret_required();
1091                 init_features.set_basic_mpp_optional();
1092                 init_features.set_wumbo_optional();
1093                 init_features.set_anchors_zero_fee_htlc_tx_optional();
1094                 init_features.set_route_blinding_optional();
1095                 init_features.set_shutdown_any_segwit_optional();
1096                 init_features.set_onion_messages_optional();
1097                 init_features.set_channel_type_optional();
1098                 init_features.set_scid_privacy_optional();
1099                 init_features.set_zero_conf_optional();
1100
1101                 assert!(init_features.initial_routing_sync());
1102                 assert!(!init_features.supports_upfront_shutdown_script());
1103                 assert!(!init_features.supports_gossip_queries());
1104
1105                 let node_features: NodeFeatures = init_features.to_context();
1106                 {
1107                         // Check that the flags are as expected:
1108                         // - option_data_loss_protect (req)
1109                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
1110                         // - basic_mpp | wumbo | option_anchors_zero_fee_htlc_tx
1111                         // - option_route_blinding | opt_shutdown_anysegwit
1112                         // - onion_messages
1113                         // - option_channel_type | option_scid_alias
1114                         // - option_zeroconf
1115                         assert_eq!(node_features.flags.len(), 7);
1116                         assert_eq!(node_features.flags[0], 0b00000001);
1117                         assert_eq!(node_features.flags[1], 0b01010001);
1118                         assert_eq!(node_features.flags[2], 0b10001010);
1119                         assert_eq!(node_features.flags[3], 0b00001010);
1120                         assert_eq!(node_features.flags[4], 0b10000000);
1121                         assert_eq!(node_features.flags[5], 0b10100000);
1122                         assert_eq!(node_features.flags[6], 0b00001000);
1123                 }
1124
1125                 // Check that cleared flags are kept blank when converting back:
1126                 // - initial_routing_sync was not applicable to NodeContext
1127                 // - upfront_shutdown_script was cleared before converting
1128                 // - gossip_queries was cleared before converting
1129                 let features: InitFeatures = node_features.to_context_internal();
1130                 assert!(!features.initial_routing_sync());
1131                 assert!(!features.supports_upfront_shutdown_script());
1132                 assert!(!init_features.supports_gossip_queries());
1133         }
1134
1135         #[test]
1136         fn convert_to_context_with_unknown_flags() {
1137                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1138                 assert!(<sealed::ChannelContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
1139                         <sealed::Bolt11InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
1140                 let mut channel_features = ChannelFeatures::empty();
1141                 channel_features.set_unknown_feature_optional();
1142                 assert!(channel_features.supports_unknown_bits());
1143                 let invoice_features: Bolt11InvoiceFeatures = channel_features.to_context_internal();
1144                 assert!(!invoice_features.supports_unknown_bits());
1145         }
1146
1147         #[test]
1148         fn set_feature_bits() {
1149                 let mut features = Bolt11InvoiceFeatures::empty();
1150                 features.set_basic_mpp_optional();
1151                 features.set_payment_secret_required();
1152                 assert!(features.supports_basic_mpp());
1153                 assert!(!features.requires_basic_mpp());
1154                 assert!(features.requires_payment_secret());
1155                 assert!(features.supports_payment_secret());
1156
1157                 // Set flags manually
1158                 let mut features = NodeFeatures::empty();
1159                 assert!(features.set_optional_feature_bit(55).is_ok());
1160                 assert!(features.supports_keysend());
1161                 assert!(features.set_optional_feature_bit(255).is_ok());
1162                 assert!(features.set_required_feature_bit(256).is_err());
1163         }
1164
1165         #[test]
1166         fn set_custom_bits() {
1167                 let mut features = Bolt11InvoiceFeatures::empty();
1168                 features.set_variable_length_onion_optional();
1169                 assert_eq!(features.flags[1], 0b00000010);
1170
1171                 assert!(features.set_optional_custom_bit(255).is_err());
1172                 assert!(features.set_required_custom_bit(256).is_ok());
1173                 assert!(features.set_required_custom_bit(258).is_ok());
1174                 assert_eq!(features.flags[31], 0b00000000);
1175                 assert_eq!(features.flags[32], 0b00000101);
1176
1177                 let known_bit = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::EVEN_BIT;
1178                 let byte_offset = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::BYTE_OFFSET;
1179                 assert_eq!(byte_offset, 1);
1180                 assert_eq!(features.flags[byte_offset], 0b00000010);
1181                 assert!(features.set_required_custom_bit(known_bit).is_err());
1182                 assert_eq!(features.flags[byte_offset], 0b00000010);
1183
1184                 let mut features = Bolt11InvoiceFeatures::empty();
1185                 assert!(features.set_optional_custom_bit(256).is_ok());
1186                 assert!(features.set_optional_custom_bit(259).is_ok());
1187                 assert_eq!(features.flags[32], 0b00001010);
1188
1189                 let mut features = Bolt11InvoiceFeatures::empty();
1190                 assert!(features.set_required_custom_bit(257).is_ok());
1191                 assert!(features.set_required_custom_bit(258).is_ok());
1192                 assert_eq!(features.flags[32], 0b00000101);
1193         }
1194
1195         #[test]
1196         fn encodes_features_without_length() {
1197                 let features = OfferFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1198                 assert_eq!(features.flags.len(), 8);
1199
1200                 let mut serialized_features = Vec::new();
1201                 WithoutLength(&features).write(&mut serialized_features).unwrap();
1202                 assert_eq!(serialized_features.len(), 8);
1203
1204                 let deserialized_features =
1205                         WithoutLength::<OfferFeatures>::read(&mut &serialized_features[..]).unwrap().0;
1206                 assert_eq!(features, deserialized_features);
1207         }
1208
1209         #[test]
1210         fn invoice_features_encoding() {
1211                 let features_as_u5s = vec![
1212                         u5::try_from_u8(6).unwrap(),
1213                         u5::try_from_u8(10).unwrap(),
1214                         u5::try_from_u8(25).unwrap(),
1215                         u5::try_from_u8(1).unwrap(),
1216                         u5::try_from_u8(10).unwrap(),
1217                         u5::try_from_u8(0).unwrap(),
1218                         u5::try_from_u8(20).unwrap(),
1219                         u5::try_from_u8(2).unwrap(),
1220                         u5::try_from_u8(0).unwrap(),
1221                         u5::try_from_u8(6).unwrap(),
1222                         u5::try_from_u8(0).unwrap(),
1223                         u5::try_from_u8(16).unwrap(),
1224                         u5::try_from_u8(1).unwrap(),
1225                 ];
1226                 let features = Bolt11InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1227
1228                 // Test length calculation.
1229                 assert_eq!(features.base32_len(), 13);
1230
1231                 // Test serialization.
1232                 let features_serialized = features.to_base32();
1233                 assert_eq!(features_as_u5s, features_serialized);
1234
1235                 // Test deserialization.
1236                 let features_deserialized = Bolt11InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1237                 assert_eq!(features, features_deserialized);
1238         }
1239
1240         #[test]
1241         fn test_channel_type_mapping() {
1242                 // If we map an Bolt11InvoiceFeatures with StaticRemoteKey optional, it should map into a
1243                 // required-StaticRemoteKey ChannelTypeFeatures.
1244                 let mut init_features = InitFeatures::empty();
1245                 init_features.set_static_remote_key_optional();
1246                 let converted_features = ChannelTypeFeatures::from_init(&init_features);
1247                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1248                 assert!(!converted_features.supports_any_optional_bits());
1249                 assert!(converted_features.requires_static_remote_key());
1250         }
1251
1252         #[test]
1253         #[cfg(feature = "std")]
1254         fn test_excess_zero_bytes_ignored() {
1255                 // Checks that `Hash` and `PartialEq` ignore excess zero bytes, which may appear due to
1256                 // feature conversion or because a peer serialized their feature poorly.
1257                 use std::collections::hash_map::DefaultHasher;
1258                 use std::hash::{Hash, Hasher};
1259
1260                 let mut zerod_features = InitFeatures::empty();
1261                 zerod_features.flags = vec![0];
1262                 let empty_features = InitFeatures::empty();
1263                 assert!(empty_features.flags.is_empty());
1264
1265                 assert_eq!(zerod_features, empty_features);
1266
1267                 let mut zerod_hash = DefaultHasher::new();
1268                 zerod_features.hash(&mut zerod_hash);
1269                 let mut empty_hash = DefaultHasher::new();
1270                 empty_features.hash(&mut empty_hash);
1271                 assert_eq!(zerod_hash.finish(), empty_hash.finish());
1272         }
1273 }