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