1 // This file is Copyright its original authors, visible in version control
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
10 //! Feature flag definitions for the Lightning protocol according to [BOLT #9].
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).
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.
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).
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 //! - `ShutdownAnySegwit` - requires/supports that future segwit versions are allowed in `shutdown`
43 //! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
44 //! - `ChannelType` - node supports the channel_type field in open/accept
45 //! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
46 //! - `SCIDPrivacy` - supply channel aliases for routing
47 //! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
48 //! - `Keysend` - send funds to a node without an invoice
49 //! (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
51 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
52 //! [messages]: crate::ln::msgs
57 use core::hash::{Hash, Hasher};
58 use core::marker::PhantomData;
61 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
62 use ln::msgs::DecodeError;
63 use util::ser::{Readable, Writeable, Writer};
67 use ln::features::Features;
69 /// The context in which [`Features`] are applicable. Defines which features are required and
70 /// which are optional for the context.
72 /// Features that are known to the implementation, where a required feature is indicated by
73 /// its even bit and an optional feature is indicated by its odd bit.
74 const KNOWN_FEATURE_FLAGS: &'static [u8];
76 /// Bitmask for selecting features that are known to the implementation, regardless of
77 /// whether each feature is required or optional.
78 const KNOWN_FEATURE_MASK: &'static [u8];
81 /// Defines a [`Context`] by stating which features it requires and which are optional. Features
82 /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
83 /// feature identifiers.
84 macro_rules! define_context {
86 required_features: [$( $( $required_feature: ident )|*, )*],
87 optional_features: [$( $( $optional_feature: ident )|*, )*],
89 #[derive(Eq, PartialEq)]
90 pub struct $context {}
92 impl Context for $context {
93 const KNOWN_FEATURE_FLAGS: &'static [u8] = &[
94 // For each byte, use bitwise-OR to compute the applicable flags for known
95 // required features `r_i` and optional features `o_j` for all `i` and `j` such
96 // that the following slice is formed:
99 // `r_0` | `r_1` | ... | `o_0` | `o_1` | ...,
104 <Self as $required_feature>::REQUIRED_MASK)*
106 <Self as $optional_feature>::OPTIONAL_MASK)*,
110 const KNOWN_FEATURE_MASK: &'static [u8] = &[
111 // Similar as above, but set both flags for each feature regardless of whether
112 // the feature is required or optional.
115 <Self as $required_feature>::REQUIRED_MASK |
116 <Self as $required_feature>::OPTIONAL_MASK)*
118 <Self as $optional_feature>::REQUIRED_MASK |
119 <Self as $optional_feature>::OPTIONAL_MASK)*,
124 impl alloc::fmt::Display for Features<$context> {
125 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
128 fmt.write_fmt(format_args!("{}: {}, ", stringify!($required_feature),
129 if <$context as $required_feature>::requires_feature(&self.flags) { "required" }
130 else if <$context as $required_feature>::supports_feature(&self.flags) { "supported" }
131 else { "not supported" }))?;
134 fmt.write_fmt(format_args!("{}: {}, ", stringify!($optional_feature),
135 if <$context as $optional_feature>::requires_feature(&self.flags) { "required" }
136 else if <$context as $optional_feature>::supports_feature(&self.flags) { "supported" }
137 else { "not supported" }))?;
140 fmt.write_fmt(format_args!("unknown flags: {}",
141 if self.requires_unknown_bits() { "required" }
142 else if self.supports_unknown_bits() { "supported" } else { "none" }))
148 define_context!(InitContext {
153 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
167 DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
177 ChannelType | SCIDPrivacy,
182 define_context!(NodeContext {
187 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
201 DataLossProtect | UpfrontShutdownScript | GossipQueries,
211 ChannelType | SCIDPrivacy,
216 define_context!(ChannelContext {
217 required_features: [],
218 optional_features: [],
220 define_context!(InvoiceContext {
225 VariableLengthOnion | PaymentSecret,
238 // This isn't a "real" feature context, and is only used in the channel_type field in an
239 // `OpenChannel` message.
240 define_context!(ChannelTypeContext {
275 /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
276 /// useful for manipulating feature flags.
277 macro_rules! define_feature {
278 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
279 $required_setter: ident, $supported_getter: ident) => {
282 /// See [BOLT #9] for details.
284 /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
285 pub trait $feature: Context {
286 /// The bit used to signify that the feature is required.
287 const EVEN_BIT: usize = $odd_bit - 1;
289 /// The bit used to signify that the feature is optional.
290 const ODD_BIT: usize = $odd_bit;
292 /// Assertion that [`EVEN_BIT`] is actually even.
294 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
295 const ASSERT_EVEN_BIT_PARITY: usize;
297 /// Assertion that [`ODD_BIT`] is actually odd.
299 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
300 const ASSERT_ODD_BIT_PARITY: usize;
302 /// The byte where the feature is set.
303 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
305 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
307 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
308 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
310 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
312 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
313 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
315 /// Returns whether the feature is required by the given flags.
317 fn requires_feature(flags: &Vec<u8>) -> bool {
318 flags.len() > Self::BYTE_OFFSET &&
319 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
322 /// Returns whether the feature is supported by the given flags.
324 fn supports_feature(flags: &Vec<u8>) -> bool {
325 flags.len() > Self::BYTE_OFFSET &&
326 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
329 /// Sets the feature's required (even) bit in the given flags.
331 fn set_required_bit(flags: &mut Vec<u8>) {
332 if flags.len() <= Self::BYTE_OFFSET {
333 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
336 flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
339 /// Sets the feature's optional (odd) bit in the given flags.
341 fn set_optional_bit(flags: &mut Vec<u8>) {
342 if flags.len() <= Self::BYTE_OFFSET {
343 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
346 flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
349 /// Clears the feature's required (even) and optional (odd) bits from the given
352 fn clear_bits(flags: &mut Vec<u8>) {
353 if flags.len() > Self::BYTE_OFFSET {
354 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
355 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
358 let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
359 let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
360 flags.resize(size, 0u8);
364 impl <T: $feature> Features<T> {
365 /// Set this feature as optional.
366 pub fn $optional_setter(&mut self) {
367 <T as $feature>::set_optional_bit(&mut self.flags);
370 /// Set this feature as required.
371 pub fn $required_setter(&mut self) {
372 <T as $feature>::set_required_bit(&mut self.flags);
375 /// Checks if this feature is supported.
376 pub fn $supported_getter(&self) -> bool {
377 <T as $feature>::supports_feature(&self.flags)
382 impl $feature for $context {
384 const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
387 const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
391 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
392 $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
393 define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
394 impl <T: $feature> Features<T> {
395 /// Checks if this feature is required.
396 pub fn $required_getter(&self) -> bool {
397 <T as $feature>::requires_feature(&self.flags)
403 define_feature!(1, DataLossProtect, [InitContext, NodeContext],
404 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
405 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
406 // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
407 define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
408 set_initial_routing_sync_optional, set_initial_routing_sync_required,
409 initial_routing_sync);
410 define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
411 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
412 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
413 requires_upfront_shutdown_script);
414 define_feature!(7, GossipQueries, [InitContext, NodeContext],
415 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
416 supports_gossip_queries, requires_gossip_queries);
417 define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
418 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
419 set_variable_length_onion_required, supports_variable_length_onion,
420 requires_variable_length_onion);
421 define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
422 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
423 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
424 define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
425 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
426 supports_payment_secret, requires_payment_secret);
427 define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext],
428 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
429 supports_basic_mpp, requires_basic_mpp);
430 define_feature!(19, Wumbo, [InitContext, NodeContext],
431 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
432 supports_wumbo, requires_wumbo);
433 define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
434 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
435 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
436 define_feature!(45, ChannelType, [InitContext, NodeContext],
437 "Feature flags for `option_channel_type`.", set_channel_type_optional,
438 set_channel_type_required, supports_channel_type, requires_channel_type);
439 define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
440 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
441 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
442 define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
443 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
444 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
445 define_feature!(55, Keysend, [NodeContext],
446 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
447 supports_keysend, requires_keysend);
450 define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext, InvoiceContext],
451 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
452 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
455 /// Tracks the set of features which a node implements, templated by the context in which it
458 /// (C-not exported) as we map the concrete feature types below directly instead
460 pub struct Features<T: sealed::Context> {
461 /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
463 mark: PhantomData<T>,
466 impl<T: sealed::Context> Clone for Features<T> {
467 fn clone(&self) -> Self {
469 flags: self.flags.clone(),
474 impl<T: sealed::Context> Hash for Features<T> {
475 fn hash<H: Hasher>(&self, hasher: &mut H) {
476 self.flags.hash(hasher);
479 impl<T: sealed::Context> PartialEq for Features<T> {
480 fn eq(&self, o: &Self) -> bool {
481 self.flags.eq(&o.flags)
484 impl<T: sealed::Context> fmt::Debug for Features<T> {
485 fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
490 /// Features used within an `init` message.
491 pub type InitFeatures = Features<sealed::InitContext>;
492 /// Features used within a `node_announcement` message.
493 pub type NodeFeatures = Features<sealed::NodeContext>;
494 /// Features used within a `channel_announcement` message.
495 pub type ChannelFeatures = Features<sealed::ChannelContext>;
496 /// Features used within an invoice.
497 pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
499 /// Features used within the channel_type field in an OpenChannel message.
501 /// A channel is always of some known "type", describing the transaction formats used and the exact
502 /// semantics of our interaction with our peer.
504 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
505 /// the counterparty, only required features are allowed here.
507 /// This is serialized differently from other feature types - it is not prefixed by a length, and
508 /// thus must only appear inside a TLV where its length is known in advance.
509 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
512 /// Writes all features present up to, and including, 13.
513 pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
514 let len = cmp::min(2, self.flags.len());
515 (len as u16).write(w)?;
516 for i in (0..len).rev() {
518 self.flags[i].write(w)?;
520 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
521 // up-to-and-including-bit-5, 0-indexed, on this byte:
522 (self.flags[i] & 0b00_11_11_11).write(w)?;
528 /// or's another InitFeatures into this one.
529 pub(crate) fn or(mut self, o: InitFeatures) -> InitFeatures {
530 let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
531 self.flags.resize(total_feature_len, 0u8);
532 for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
538 /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
539 /// are included in the result.
540 pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
541 self.to_context_internal()
545 impl InvoiceFeatures {
546 /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
547 /// context `C` are included in the result.
548 pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
549 self.to_context_internal()
552 /// Getting a route for a keysend payment to a private node requires providing the payee's
553 /// features (since they were not announced in a node announcement). However, keysend payments
554 /// don't have an invoice to pull the payee's features from, so this method is provided for use in
555 /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
556 /// `InvoiceFeatures` for [`find_route`].
558 /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
559 /// [`find_route`]: crate::routing::router::find_route
560 pub(crate) fn for_keysend() -> InvoiceFeatures {
561 let mut res = InvoiceFeatures::empty();
562 res.set_variable_length_onion_optional();
567 impl ChannelTypeFeatures {
568 /// Constructs the implicit channel type based on the common supported types between us and our
570 pub(crate) fn from_counterparty_init(counterparty_init: &InitFeatures) -> Self {
571 let mut ret = counterparty_init.to_context_internal();
572 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
573 // optional bits and then AND out the optional ones.
574 for byte in ret.flags.iter_mut() {
575 *byte |= (*byte & 0b10_10_10_10) >> 1;
576 *byte &= 0b01_01_01_01;
581 /// Constructs a ChannelTypeFeatures with only static_remotekey set
582 pub(crate) fn only_static_remote_key() -> Self {
583 let mut ret = Self::empty();
584 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
589 impl ToBase32 for InvoiceFeatures {
590 fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
591 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
592 // minus one before dividing
593 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
594 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
595 for (byte_idx, byte) in self.flags.iter().enumerate() {
596 let bit_pos_from_left_0_indexed = byte_idx * 8;
597 let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
598 let new_bit_pos = bit_pos_from_left_0_indexed % 5;
599 let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
600 let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
601 res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
603 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
604 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
607 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
608 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
611 // Trim the highest feature bits.
612 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
615 writer.write(&res_u5s)
619 impl Base32Len for InvoiceFeatures {
620 fn base32_len(&self) -> usize {
621 self.to_base32().len()
625 impl FromBase32 for InvoiceFeatures {
626 type Err = bech32::Error;
628 fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
629 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
630 // minus one before dividing
631 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
632 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
633 for (u5_idx, chunk) in field_data.iter().enumerate() {
634 let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
635 let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
636 let new_bit_pos = bit_pos_from_right_0_indexed % 8;
637 let chunk_u16 = chunk.to_u8() as u16;
638 res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
639 if new_byte_idx != length_bytes - 1 {
640 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
643 // Trim the highest feature bits.
644 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
647 Ok(InvoiceFeatures::from_le_bytes(res_bytes))
651 impl<T: sealed::Context> Features<T> {
652 /// Create a blank Features with no features set
653 pub fn empty() -> Self {
660 /// Creates a Features with the bits set which are known by the implementation
661 pub fn known() -> Self {
663 flags: T::KNOWN_FEATURE_FLAGS.to_vec(),
668 /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
669 /// included in the result.
670 fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
671 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
672 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
673 let mut flags = Vec::new();
674 for (i, byte) in self.flags.iter().enumerate() {
675 if i < from_byte_count && i < to_byte_count {
676 let from_known_features = T::KNOWN_FEATURE_MASK[i];
677 let to_known_features = C::KNOWN_FEATURE_MASK[i];
678 flags.push(byte & from_known_features & to_known_features);
681 Features::<C> { flags, mark: PhantomData, }
684 /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
685 /// most on-the-wire encodings.
686 /// (C-not exported) as we don't support export across multiple T
687 pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
695 /// Gets the underlying flags set, in LE.
696 pub fn le_flags(&self) -> &Vec<u8> {
700 fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
701 for f in self.flags.iter().rev() { // Swap back to big-endian
707 fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
708 flags.reverse(); // Swap to little-endian
715 pub(crate) fn supports_any_optional_bits(&self) -> bool {
716 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
719 /// Returns true if this `Features` object contains unknown feature flags which are set as
721 pub fn requires_unknown_bits(&self) -> bool {
722 // Bitwise AND-ing with all even bits set except for known features will select required
724 let byte_count = T::KNOWN_FEATURE_MASK.len();
725 self.flags.iter().enumerate().any(|(i, &byte)| {
726 let required_features = 0b01_01_01_01;
727 let unknown_features = if i < byte_count {
728 !T::KNOWN_FEATURE_MASK[i]
732 (byte & (required_features & unknown_features)) != 0
736 pub(crate) fn supports_unknown_bits(&self) -> bool {
737 // Bitwise AND-ing with all even and odd bits set except for known features will select
738 // both required and optional unknown features.
739 let byte_count = T::KNOWN_FEATURE_MASK.len();
740 self.flags.iter().enumerate().any(|(i, &byte)| {
741 let unknown_features = if i < byte_count {
742 !T::KNOWN_FEATURE_MASK[i]
746 (byte & unknown_features) != 0
751 impl<T: sealed::UpfrontShutdownScript> Features<T> {
753 pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
754 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
760 impl<T: sealed::GossipQueries> Features<T> {
762 pub(crate) fn clear_gossip_queries(mut self) -> Self {
763 <T as sealed::GossipQueries>::clear_bits(&mut self.flags);
768 impl<T: sealed::InitialRoutingSync> Features<T> {
769 // We are no longer setting initial_routing_sync now that gossip_queries
770 // is enabled. This feature is ignored by a peer when gossip_queries has
773 pub(crate) fn clear_initial_routing_sync(&mut self) {
774 <T as sealed::InitialRoutingSync>::clear_bits(&mut self.flags)
778 impl<T: sealed::ShutdownAnySegwit> Features<T> {
780 pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
781 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
786 impl<T: sealed::Wumbo> Features<T> {
788 pub(crate) fn clear_wumbo(mut self) -> Self {
789 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
794 macro_rules! impl_feature_len_prefixed_write {
795 ($features: ident) => {
796 impl Writeable for $features {
797 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
798 (self.flags.len() as u16).write(w)?;
802 impl Readable for $features {
803 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
804 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
809 impl_feature_len_prefixed_write!(InitFeatures);
810 impl_feature_len_prefixed_write!(ChannelFeatures);
811 impl_feature_len_prefixed_write!(NodeFeatures);
812 impl_feature_len_prefixed_write!(InvoiceFeatures);
814 // Because ChannelTypeFeatures only appears inside of TLVs, it doesn't have a length prefix when
815 // serialized. Thus, we can't use `impl_feature_len_prefixed_write`, above, and have to write our
816 // own serialization.
817 impl Writeable for ChannelTypeFeatures {
818 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
822 impl Readable for ChannelTypeFeatures {
823 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
824 let v = io_extras::read_to_end(r)?;
825 Ok(Self::from_be_bytes(v))
831 use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
832 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
835 fn sanity_test_known_features() {
836 assert!(!ChannelFeatures::known().requires_unknown_bits());
837 assert!(!ChannelFeatures::known().supports_unknown_bits());
838 assert!(!InitFeatures::known().requires_unknown_bits());
839 assert!(!InitFeatures::known().supports_unknown_bits());
840 assert!(!NodeFeatures::known().requires_unknown_bits());
841 assert!(!NodeFeatures::known().supports_unknown_bits());
843 assert!(InitFeatures::known().supports_upfront_shutdown_script());
844 assert!(NodeFeatures::known().supports_upfront_shutdown_script());
845 assert!(!InitFeatures::known().requires_upfront_shutdown_script());
846 assert!(!NodeFeatures::known().requires_upfront_shutdown_script());
848 assert!(InitFeatures::known().supports_gossip_queries());
849 assert!(NodeFeatures::known().supports_gossip_queries());
850 assert!(!InitFeatures::known().requires_gossip_queries());
851 assert!(!NodeFeatures::known().requires_gossip_queries());
853 assert!(InitFeatures::known().supports_data_loss_protect());
854 assert!(NodeFeatures::known().supports_data_loss_protect());
855 assert!(!InitFeatures::known().requires_data_loss_protect());
856 assert!(!NodeFeatures::known().requires_data_loss_protect());
858 assert!(InitFeatures::known().supports_variable_length_onion());
859 assert!(NodeFeatures::known().supports_variable_length_onion());
860 assert!(InvoiceFeatures::known().supports_variable_length_onion());
861 assert!(InitFeatures::known().requires_variable_length_onion());
862 assert!(NodeFeatures::known().requires_variable_length_onion());
863 assert!(InvoiceFeatures::known().requires_variable_length_onion());
865 assert!(InitFeatures::known().supports_static_remote_key());
866 assert!(NodeFeatures::known().supports_static_remote_key());
867 assert!(InitFeatures::known().requires_static_remote_key());
868 assert!(NodeFeatures::known().requires_static_remote_key());
870 assert!(InitFeatures::known().supports_payment_secret());
871 assert!(NodeFeatures::known().supports_payment_secret());
872 assert!(InvoiceFeatures::known().supports_payment_secret());
873 assert!(InitFeatures::known().requires_payment_secret());
874 assert!(NodeFeatures::known().requires_payment_secret());
875 assert!(InvoiceFeatures::known().requires_payment_secret());
877 assert!(InitFeatures::known().supports_basic_mpp());
878 assert!(NodeFeatures::known().supports_basic_mpp());
879 assert!(InvoiceFeatures::known().supports_basic_mpp());
880 assert!(!InitFeatures::known().requires_basic_mpp());
881 assert!(!NodeFeatures::known().requires_basic_mpp());
882 assert!(!InvoiceFeatures::known().requires_basic_mpp());
884 assert!(InitFeatures::known().supports_channel_type());
885 assert!(NodeFeatures::known().supports_channel_type());
886 assert!(!InitFeatures::known().requires_channel_type());
887 assert!(!NodeFeatures::known().requires_channel_type());
889 assert!(InitFeatures::known().supports_shutdown_anysegwit());
890 assert!(NodeFeatures::known().supports_shutdown_anysegwit());
892 assert!(InitFeatures::known().supports_scid_privacy());
893 assert!(NodeFeatures::known().supports_scid_privacy());
894 assert!(ChannelTypeFeatures::known().supports_scid_privacy());
895 assert!(!InitFeatures::known().requires_scid_privacy());
896 assert!(!NodeFeatures::known().requires_scid_privacy());
897 assert!(ChannelTypeFeatures::known().requires_scid_privacy());
899 assert!(InitFeatures::known().supports_wumbo());
900 assert!(NodeFeatures::known().supports_wumbo());
901 assert!(!InitFeatures::known().requires_wumbo());
902 assert!(!NodeFeatures::known().requires_wumbo());
904 assert!(InitFeatures::known().supports_zero_conf());
905 assert!(!InitFeatures::known().requires_zero_conf());
906 assert!(NodeFeatures::known().supports_zero_conf());
907 assert!(!NodeFeatures::known().requires_zero_conf());
908 assert!(ChannelTypeFeatures::known().supports_zero_conf());
909 assert!(ChannelTypeFeatures::known().requires_zero_conf());
911 let mut init_features = InitFeatures::known();
912 assert!(init_features.initial_routing_sync());
913 init_features.clear_initial_routing_sync();
914 assert!(!init_features.initial_routing_sync());
918 fn sanity_test_unknown_bits() {
919 let features = ChannelFeatures::empty();
920 assert!(!features.requires_unknown_bits());
921 assert!(!features.supports_unknown_bits());
923 let mut features = ChannelFeatures::empty();
924 features.set_unknown_feature_required();
925 assert!(features.requires_unknown_bits());
926 assert!(features.supports_unknown_bits());
928 let mut features = ChannelFeatures::empty();
929 features.set_unknown_feature_optional();
930 assert!(!features.requires_unknown_bits());
931 assert!(features.supports_unknown_bits());
935 fn convert_to_context_with_relevant_flags() {
936 let init_features = InitFeatures::known().clear_upfront_shutdown_script().clear_gossip_queries();
937 assert!(init_features.initial_routing_sync());
938 assert!(!init_features.supports_upfront_shutdown_script());
939 assert!(!init_features.supports_gossip_queries());
941 let node_features: NodeFeatures = init_features.to_context();
943 // Check that the flags are as expected:
944 // - option_data_loss_protect
945 // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
946 // - basic_mpp | wumbo
947 // - opt_shutdown_anysegwit
949 // - option_channel_type | option_scid_alias
951 assert_eq!(node_features.flags.len(), 7);
952 assert_eq!(node_features.flags[0], 0b00000010);
953 assert_eq!(node_features.flags[1], 0b01010001);
954 assert_eq!(node_features.flags[2], 0b00001010);
955 assert_eq!(node_features.flags[3], 0b00001000);
956 assert_eq!(node_features.flags[4], 0b00000000);
957 assert_eq!(node_features.flags[5], 0b10100000);
958 assert_eq!(node_features.flags[6], 0b00001000);
961 // Check that cleared flags are kept blank when converting back:
962 // - initial_routing_sync was not applicable to NodeContext
963 // - upfront_shutdown_script was cleared before converting
964 // - gossip_queries was cleared before converting
965 let features: InitFeatures = node_features.to_context_internal();
966 assert!(!features.initial_routing_sync());
967 assert!(!features.supports_upfront_shutdown_script());
968 assert!(!init_features.supports_gossip_queries());
972 fn convert_to_context_with_unknown_flags() {
973 // Ensure the `from` context has fewer known feature bytes than the `to` context.
974 assert!(InvoiceFeatures::known().flags.len() < NodeFeatures::known().flags.len());
975 let mut invoice_features = InvoiceFeatures::known();
976 invoice_features.set_unknown_feature_optional();
977 assert!(invoice_features.supports_unknown_bits());
978 let node_features: NodeFeatures = invoice_features.to_context();
979 assert!(!node_features.supports_unknown_bits());
983 fn set_feature_bits() {
984 let mut features = InvoiceFeatures::empty();
985 features.set_basic_mpp_optional();
986 features.set_payment_secret_required();
987 assert!(features.supports_basic_mpp());
988 assert!(!features.requires_basic_mpp());
989 assert!(features.requires_payment_secret());
990 assert!(features.supports_payment_secret());
994 fn invoice_features_encoding() {
995 let features_as_u5s = vec![
996 u5::try_from_u8(6).unwrap(),
997 u5::try_from_u8(10).unwrap(),
998 u5::try_from_u8(25).unwrap(),
999 u5::try_from_u8(1).unwrap(),
1000 u5::try_from_u8(10).unwrap(),
1001 u5::try_from_u8(0).unwrap(),
1002 u5::try_from_u8(20).unwrap(),
1003 u5::try_from_u8(2).unwrap(),
1004 u5::try_from_u8(0).unwrap(),
1005 u5::try_from_u8(6).unwrap(),
1006 u5::try_from_u8(0).unwrap(),
1007 u5::try_from_u8(16).unwrap(),
1008 u5::try_from_u8(1).unwrap(),
1010 let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1012 // Test length calculation.
1013 assert_eq!(features.base32_len(), 13);
1015 // Test serialization.
1016 let features_serialized = features.to_base32();
1017 assert_eq!(features_as_u5s, features_serialized);
1019 // Test deserialization.
1020 let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1021 assert_eq!(features, features_deserialized);
1025 fn test_channel_type_mapping() {
1026 // If we map an InvoiceFeatures with StaticRemoteKey optional, it should map into a
1027 // required-StaticRemoteKey ChannelTypeFeatures.
1028 let mut init_features = InitFeatures::empty();
1029 init_features.set_static_remote_key_optional();
1030 let converted_features = ChannelTypeFeatures::from_counterparty_init(&init_features);
1031 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1032 assert!(!converted_features.supports_any_optional_bits());
1033 assert!(converted_features.requires_static_remote_key());