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 //! - `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
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).
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
61 //! (see [BOLT-11](https://github.com/lightning/bolts/blob/master/11-payment-encoding.md) for
63 //! - `ZeroConf` - supports accepting HTLCs and using channels prior to funding confirmation
65 //! [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-channel_ready-message)
67 //! - `Keysend` - send funds to a node without an invoice
68 //! (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
69 //! - `Trampoline` - supports receiving and forwarding Trampoline payments
70 //! (see the [`Trampoline` feature proposal](https://github.com/lightning/bolts/pull/836) for more information).
72 //! LDK knows about the following features, but does not support them:
73 //! - `AnchorsNonzeroFeeHtlcTx` - the initial version of anchor outputs, which was later found to be
74 //! vulnerable (see this
75 //! [mailing list post](https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-September/002796.html)
76 //! for more information).
78 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
79 //! [messages]: crate::ln::msgs
81 use crate::{io, io_extras};
82 use crate::prelude::*;
84 use core::borrow::Borrow;
85 use core::hash::{Hash, Hasher};
86 use core::marker::PhantomData;
89 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
90 use crate::ln::msgs::DecodeError;
91 use crate::util::ser::{Readable, WithoutLength, Writeable, Writer};
94 use crate::prelude::*;
95 use crate::ln::features::Features;
97 /// The context in which [`Features`] are applicable. Defines which features are known to the
98 /// implementation, though specification of them as required or optional is up to the code
99 /// constructing a features object.
101 /// Bitmask for selecting features that are known to the implementation.
102 const KNOWN_FEATURE_MASK: &'static [u8];
105 /// Defines a [`Context`] by stating which features it requires and which are optional. Features
106 /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
107 /// feature identifiers.
108 macro_rules! define_context {
109 ($context: ident, [$( $( $known_feature: ident )|*, )*]) => {
110 #[derive(Eq, PartialEq)]
111 pub struct $context {}
113 impl Context for $context {
114 const KNOWN_FEATURE_MASK: &'static [u8] = &[
117 <Self as $known_feature>::REQUIRED_MASK |
118 <Self as $known_feature>::OPTIONAL_MASK)*,
123 impl alloc::fmt::Display for Features<$context> {
124 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
127 fmt.write_fmt(format_args!("{}: {}, ", stringify!($known_feature),
128 if <$context as $known_feature>::requires_feature(&self.flags) { "required" }
129 else if <$context as $known_feature>::supports_feature(&self.flags) { "supported" }
130 else { "not supported" }))?;
132 {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
134 fmt.write_fmt(format_args!("unknown flags: {}",
135 if self.requires_unknown_bits() { "required" }
136 else if self.supports_unknown_bits() { "supported" } else { "none" }))
142 define_context!(InitContext, [
144 DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
146 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
148 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
150 RouteBlinding | ShutdownAnySegwit | Taproot,
154 ChannelType | SCIDPrivacy,
160 define_context!(NodeContext, [
162 DataLossProtect | UpfrontShutdownScript | GossipQueries,
164 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
166 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
168 RouteBlinding | ShutdownAnySegwit | Taproot,
172 ChannelType | SCIDPrivacy,
178 define_context!(ChannelContext, []);
179 define_context!(Bolt11InvoiceContext, [
183 VariableLengthOnion | PaymentSecret,
197 define_context!(OfferContext, []);
198 define_context!(InvoiceRequestContext, []);
199 define_context!(Bolt12InvoiceContext, [
207 define_context!(BlindedHopContext, []);
208 // This isn't a "real" feature context, and is only used in the channel_type field in an
209 // `OpenChannel` message.
210 define_context!(ChannelTypeContext, [
216 AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
227 /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
228 /// useful for manipulating feature flags.
229 macro_rules! define_feature {
230 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
231 $required_setter: ident, $supported_getter: ident) => {
234 /// See [BOLT #9] for details.
236 /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
237 pub trait $feature: Context {
238 /// The bit used to signify that the feature is required.
239 const EVEN_BIT: usize = $odd_bit - 1;
241 /// The bit used to signify that the feature is optional.
242 const ODD_BIT: usize = $odd_bit;
244 /// Assertion that [`EVEN_BIT`] is actually even.
246 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
247 const ASSERT_EVEN_BIT_PARITY: usize;
249 /// Assertion that [`ODD_BIT`] is actually odd.
251 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
252 const ASSERT_ODD_BIT_PARITY: usize;
254 /// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
256 /// [`KNOWN_FEATURE_MASK`]: Context::KNOWN_FEATURE_MASK
257 #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
258 const ASSERT_BITS_IN_MASK: u8;
260 /// The byte where the feature is set.
261 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
263 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
265 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
266 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
268 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
270 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
271 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
273 /// Returns whether the feature is required by the given flags.
275 fn requires_feature(flags: &Vec<u8>) -> bool {
276 flags.len() > Self::BYTE_OFFSET &&
277 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
280 /// Returns whether the feature is supported by the given flags.
282 fn supports_feature(flags: &Vec<u8>) -> bool {
283 flags.len() > Self::BYTE_OFFSET &&
284 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
287 /// Sets the feature's required (even) bit in the given flags.
289 fn set_required_bit(flags: &mut Vec<u8>) {
290 if flags.len() <= Self::BYTE_OFFSET {
291 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
294 flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
295 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
298 /// Sets the feature's optional (odd) bit in the given flags.
300 fn set_optional_bit(flags: &mut Vec<u8>) {
301 if flags.len() <= Self::BYTE_OFFSET {
302 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
305 flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
308 /// Clears the feature's required (even) and optional (odd) bits from the given
311 fn clear_bits(flags: &mut Vec<u8>) {
312 if flags.len() > Self::BYTE_OFFSET {
313 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
314 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
317 let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
318 let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
319 flags.resize(size, 0u8);
323 impl <T: $feature> Features<T> {
324 /// Set this feature as optional.
325 pub fn $optional_setter(&mut self) {
326 <T as $feature>::set_optional_bit(&mut self.flags);
329 /// Set this feature as required.
330 pub fn $required_setter(&mut self) {
331 <T as $feature>::set_required_bit(&mut self.flags);
334 /// Checks if this feature is supported.
335 pub fn $supported_getter(&self) -> bool {
336 <T as $feature>::supports_feature(&self.flags)
341 impl $feature for $context {
343 const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
346 const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
348 // (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
349 #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
350 const ASSERT_BITS_IN_MASK: u8 =
351 ((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
352 >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
356 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
357 $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
358 define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
359 impl <T: $feature> Features<T> {
360 /// Checks if this feature is required.
361 pub fn $required_getter(&self) -> bool {
362 <T as $feature>::requires_feature(&self.flags)
368 define_feature!(1, DataLossProtect, [InitContext, NodeContext],
369 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
370 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
371 // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
372 define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
373 set_initial_routing_sync_optional, set_initial_routing_sync_required,
374 initial_routing_sync);
375 define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
376 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
377 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
378 requires_upfront_shutdown_script);
379 define_feature!(7, GossipQueries, [InitContext, NodeContext],
380 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
381 supports_gossip_queries, requires_gossip_queries);
382 define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, Bolt11InvoiceContext],
383 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
384 set_variable_length_onion_required, supports_variable_length_onion,
385 requires_variable_length_onion);
386 define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
387 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
388 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
389 define_feature!(15, PaymentSecret, [InitContext, NodeContext, Bolt11InvoiceContext],
390 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
391 supports_payment_secret, requires_payment_secret);
392 define_feature!(17, BasicMPP, [InitContext, NodeContext, Bolt11InvoiceContext, Bolt12InvoiceContext],
393 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
394 supports_basic_mpp, requires_basic_mpp);
395 define_feature!(19, Wumbo, [InitContext, NodeContext],
396 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
397 supports_wumbo, requires_wumbo);
398 define_feature!(21, AnchorsNonzeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
399 "Feature flags for `option_anchors_nonzero_fee_htlc_tx`.", set_anchors_nonzero_fee_htlc_tx_optional,
400 set_anchors_nonzero_fee_htlc_tx_required, supports_anchors_nonzero_fee_htlc_tx, requires_anchors_nonzero_fee_htlc_tx);
401 define_feature!(23, AnchorsZeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
402 "Feature flags for `option_anchors_zero_fee_htlc_tx`.", set_anchors_zero_fee_htlc_tx_optional,
403 set_anchors_zero_fee_htlc_tx_required, supports_anchors_zero_fee_htlc_tx, requires_anchors_zero_fee_htlc_tx);
404 define_feature!(25, RouteBlinding, [InitContext, NodeContext],
405 "Feature flags for `option_route_blinding`.", set_route_blinding_optional,
406 set_route_blinding_required, supports_route_blinding, requires_route_blinding);
407 define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
408 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
409 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
410 define_feature!(31, Taproot, [InitContext, NodeContext, ChannelTypeContext],
411 "Feature flags for `option_taproot`.", set_taproot_optional,
412 set_taproot_required, supports_taproot, requires_taproot);
413 define_feature!(39, OnionMessages, [InitContext, NodeContext],
414 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
415 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
416 define_feature!(45, ChannelType, [InitContext, NodeContext],
417 "Feature flags for `option_channel_type`.", set_channel_type_optional,
418 set_channel_type_required, supports_channel_type, requires_channel_type);
419 define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
420 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
421 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
422 define_feature!(49, PaymentMetadata, [Bolt11InvoiceContext],
423 "Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
424 set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
425 define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
426 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
427 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
428 define_feature!(55, Keysend, [NodeContext],
429 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
430 supports_keysend, requires_keysend);
431 define_feature!(57, Trampoline, [InitContext, NodeContext, Bolt11InvoiceContext],
432 "Feature flags for Trampoline routing.", set_trampoline_routing_optional, set_trampoline_routing_required,
433 supports_trampoline_routing, requires_trampoline_routing);
434 // Note: update the module-level docs when a new feature bit is added!
437 define_feature!(123456789, UnknownFeature,
438 [NodeContext, ChannelContext, Bolt11InvoiceContext, OfferContext, InvoiceRequestContext, Bolt12InvoiceContext, BlindedHopContext],
439 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
440 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
443 /// Tracks the set of features which a node implements, templated by the context in which it
446 /// This is not exported to bindings users as we map the concrete feature types below directly instead
448 pub struct Features<T: sealed::Context> {
449 /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
451 mark: PhantomData<T>,
454 impl<T: sealed::Context, Rhs: Borrow<Self>> core::ops::BitOrAssign<Rhs> for Features<T> {
455 fn bitor_assign(&mut self, rhs: Rhs) {
456 let total_feature_len = cmp::max(self.flags.len(), rhs.borrow().flags.len());
457 self.flags.resize(total_feature_len, 0u8);
458 for (byte, rhs_byte) in self.flags.iter_mut().zip(rhs.borrow().flags.iter()) {
464 impl<T: sealed::Context> core::ops::BitOr for Features<T> {
467 fn bitor(mut self, o: Self) -> Self {
473 impl<T: sealed::Context> Clone for Features<T> {
474 fn clone(&self) -> Self {
476 flags: self.flags.clone(),
481 impl<T: sealed::Context> Hash for Features<T> {
482 fn hash<H: Hasher>(&self, hasher: &mut H) {
483 let mut nonzero_flags = &self.flags[..];
484 while nonzero_flags.last() == Some(&0) {
485 nonzero_flags = &nonzero_flags[..nonzero_flags.len() - 1];
487 nonzero_flags.hash(hasher);
490 impl<T: sealed::Context> PartialEq for Features<T> {
491 fn eq(&self, o: &Self) -> bool {
492 let mut o_iter = o.flags.iter();
493 let mut self_iter = self.flags.iter();
495 match (o_iter.next(), self_iter.next()) {
496 (Some(o), Some(us)) => if o != us { return false },
497 (Some(b), None) | (None, Some(b)) => if *b != 0 { return false },
498 (None, None) => return true,
503 impl<T: sealed::Context> PartialOrd for Features<T> {
504 fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
505 self.flags.partial_cmp(&other.flags)
508 impl<T: sealed::Context + Eq> Ord for Features<T> {
509 fn cmp(&self, other: &Self) -> cmp::Ordering {
510 self.flags.cmp(&other.flags)
513 impl<T: sealed::Context> fmt::Debug for Features<T> {
514 fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
519 /// Features used within an `init` message.
520 pub type InitFeatures = Features<sealed::InitContext>;
521 /// Features used within a `node_announcement` message.
522 pub type NodeFeatures = Features<sealed::NodeContext>;
523 /// Features used within a `channel_announcement` message.
524 pub type ChannelFeatures = Features<sealed::ChannelContext>;
525 /// Features used within an invoice.
526 pub type Bolt11InvoiceFeatures = Features<sealed::Bolt11InvoiceContext>;
527 /// Features used within an `offer`.
528 pub type OfferFeatures = Features<sealed::OfferContext>;
529 /// Features used within an `invoice_request`.
530 pub type InvoiceRequestFeatures = Features<sealed::InvoiceRequestContext>;
531 /// Features used within an `invoice`.
532 pub type Bolt12InvoiceFeatures = Features<sealed::Bolt12InvoiceContext>;
533 /// Features used within BOLT 4 encrypted_data_tlv and BOLT 12 blinded_payinfo
534 pub type BlindedHopFeatures = Features<sealed::BlindedHopContext>;
536 /// Features used within the channel_type field in an OpenChannel message.
538 /// A channel is always of some known "type", describing the transaction formats used and the exact
539 /// semantics of our interaction with our peer.
541 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
542 /// the counterparty, only required features are allowed here.
544 /// This is serialized differently from other feature types - it is not prefixed by a length, and
545 /// thus must only appear inside a TLV where its length is known in advance.
546 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
549 /// Writes all features present up to, and including, 13.
550 pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
551 let len = cmp::min(2, self.flags.len());
552 (len as u16).write(w)?;
553 for i in (0..len).rev() {
555 self.flags[i].write(w)?;
557 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
558 // up-to-and-including-bit-5, 0-indexed, on this byte:
559 (self.flags[i] & 0b00_11_11_11).write(w)?;
565 /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
566 /// are included in the result.
567 pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
568 self.to_context_internal()
572 impl Bolt11InvoiceFeatures {
573 /// Converts `Bolt11InvoiceFeatures` to `Features<C>`. Only known `Bolt11InvoiceFeatures` relevant to
574 /// context `C` are included in the result.
575 pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
576 self.to_context_internal()
579 /// Getting a route for a keysend payment to a private node requires providing the payee's
580 /// features (since they were not announced in a node announcement). However, keysend payments
581 /// don't have an invoice to pull the payee's features from, so this method is provided for use in
582 /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
583 /// `Bolt11InvoiceFeatures` for [`find_route`].
585 /// MPP keysend is not widely supported yet, so we parameterize support to allow the user to
586 /// choose whether their router should find multi-part routes.
588 /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
589 /// [`find_route`]: crate::routing::router::find_route
590 pub(crate) fn for_keysend(allow_mpp: bool) -> Bolt11InvoiceFeatures {
591 let mut res = Bolt11InvoiceFeatures::empty();
592 res.set_variable_length_onion_optional();
594 res.set_basic_mpp_optional();
600 impl Bolt12InvoiceFeatures {
601 /// Converts [`Bolt12InvoiceFeatures`] to [`Features<C>`]. Only known [`Bolt12InvoiceFeatures`]
602 /// relevant to context `C` are included in the result.
603 pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
604 self.to_context_internal()
608 impl ChannelTypeFeatures {
609 // Maps the relevant `InitFeatures` to `ChannelTypeFeatures`. Any unknown features to
610 // `ChannelTypeFeatures` are not included in the result.
611 pub(crate) fn from_init(init: &InitFeatures) -> Self {
612 let mut ret = init.to_context_internal();
613 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
614 // optional bits and then AND out the optional ones.
615 for byte in ret.flags.iter_mut() {
616 *byte |= (*byte & 0b10_10_10_10) >> 1;
617 *byte &= 0b01_01_01_01;
622 /// Constructs a ChannelTypeFeatures with only static_remotekey set
623 pub(crate) fn only_static_remote_key() -> Self {
624 let mut ret = Self::empty();
625 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
629 /// Constructs a ChannelTypeFeatures with anchors support
630 pub(crate) fn anchors_zero_htlc_fee_and_dependencies() -> Self {
631 let mut ret = Self::empty();
632 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
633 <sealed::ChannelTypeContext as sealed::AnchorsZeroFeeHtlcTx>::set_required_bit(&mut ret.flags);
638 impl ToBase32 for Bolt11InvoiceFeatures {
639 fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
640 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
641 // minus one before dividing
642 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
643 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
644 for (byte_idx, byte) in self.flags.iter().enumerate() {
645 let bit_pos_from_left_0_indexed = byte_idx * 8;
646 let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
647 let new_bit_pos = bit_pos_from_left_0_indexed % 5;
648 let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
649 let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
650 res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
652 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
653 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
656 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
657 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
660 // Trim the highest feature bits.
661 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
664 writer.write(&res_u5s)
668 impl Base32Len for Bolt11InvoiceFeatures {
669 fn base32_len(&self) -> usize {
670 self.to_base32().len()
674 impl FromBase32 for Bolt11InvoiceFeatures {
675 type Err = bech32::Error;
677 fn from_base32(field_data: &[u5]) -> Result<Bolt11InvoiceFeatures, bech32::Error> {
678 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
679 // minus one before dividing
680 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
681 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
682 for (u5_idx, chunk) in field_data.iter().enumerate() {
683 let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
684 let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
685 let new_bit_pos = bit_pos_from_right_0_indexed % 8;
686 let chunk_u16 = chunk.to_u8() as u16;
687 res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
688 if new_byte_idx != length_bytes - 1 {
689 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
692 // Trim the highest feature bits.
693 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
696 Ok(Bolt11InvoiceFeatures::from_le_bytes(res_bytes))
700 impl<T: sealed::Context> Features<T> {
701 /// Create a blank Features with no features set
702 pub fn empty() -> Self {
709 /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
710 /// included in the result.
711 fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
712 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
713 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
714 let mut flags = Vec::new();
715 for (i, byte) in self.flags.iter().enumerate() {
716 if i < from_byte_count && i < to_byte_count {
717 let from_known_features = T::KNOWN_FEATURE_MASK[i];
718 let to_known_features = C::KNOWN_FEATURE_MASK[i];
719 flags.push(byte & from_known_features & to_known_features);
722 Features::<C> { flags, mark: PhantomData, }
725 /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
726 /// most on-the-wire encodings.
728 /// This is not exported to bindings users as we don't support export across multiple T
729 pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
737 /// Gets the underlying flags set, in LE.
738 pub fn le_flags(&self) -> &Vec<u8> {
742 fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
743 for f in self.flags.iter().rev() { // Swap back to big-endian
749 /// Create a [`Features`] given a set of flags, in big-endian. This is in byte order from
750 /// most on-the-wire encodings.
752 /// This is not exported to bindings users as we don't support export across multiple T
753 pub fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
754 flags.reverse(); // Swap to little-endian
761 pub(crate) fn supports_any_optional_bits(&self) -> bool {
762 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
765 /// Returns true if this `Features` object contains required features unknown by `other`.
766 pub fn requires_unknown_bits_from(&self, other: &Self) -> bool {
767 // Bitwise AND-ing with all even bits set except for known features will select required
769 self.flags.iter().enumerate().any(|(i, &byte)| {
770 const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
771 const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
772 let unknown_features = if i < other.flags.len() {
773 // Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
775 | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
776 | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
780 (byte & (REQUIRED_FEATURES & unknown_features)) != 0
784 /// Returns true if this `Features` object contains unknown feature flags which are set as
786 pub fn requires_unknown_bits(&self) -> bool {
787 // Bitwise AND-ing with all even bits set except for known features will select required
789 let byte_count = T::KNOWN_FEATURE_MASK.len();
790 self.flags.iter().enumerate().any(|(i, &byte)| {
791 let required_features = 0b01_01_01_01;
792 let unknown_features = if i < byte_count {
793 !T::KNOWN_FEATURE_MASK[i]
797 (byte & (required_features & unknown_features)) != 0
801 pub(crate) fn supports_unknown_bits(&self) -> bool {
802 // Bitwise AND-ing with all even and odd bits set except for known features will select
803 // both required and optional unknown features.
804 let byte_count = T::KNOWN_FEATURE_MASK.len();
805 self.flags.iter().enumerate().any(|(i, &byte)| {
806 let unknown_features = if i < byte_count {
807 !T::KNOWN_FEATURE_MASK[i]
811 (byte & unknown_features) != 0
815 // Returns true if the features within `self` are a subset of the features within `other`.
816 pub(crate) fn is_subset(&self, other: &Self) -> bool {
817 for (idx, byte) in self.flags.iter().enumerate() {
818 if let Some(other_byte) = other.flags.get(idx) {
819 if byte & other_byte != *byte {
820 // `self` has bits set that `other` doesn't.
825 // `self` has a non-zero byte that `other` doesn't.
833 /// Sets a required feature bit. Errors if `bit` is outside the feature range as defined
836 /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
837 /// be set instead (i.e., `bit - 1`).
839 /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
840 pub fn set_required_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
841 self.set_feature_bit(bit - (bit % 2))
844 /// Sets an optional feature bit. Errors if `bit` is outside the feature range as defined
847 /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
848 /// set instead (i.e., `bit + 1`).
850 /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
851 pub fn set_optional_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
852 self.set_feature_bit(bit + (1 - (bit % 2)))
855 fn set_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
859 self.set_bit(bit, false)
862 /// Sets a required custom feature bit. Errors if `bit` is outside the custom range as defined
863 /// by [bLIP 2] or if it is a known `T` feature.
865 /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
866 /// be set instead (i.e., `bit - 1`).
868 /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
869 pub fn set_required_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
870 self.set_custom_bit(bit - (bit % 2))
873 /// Sets an optional custom feature bit. Errors if `bit` is outside the custom range as defined
874 /// by [bLIP 2] or if it is a known `T` feature.
876 /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
877 /// set instead (i.e., `bit + 1`).
879 /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
880 pub fn set_optional_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
881 self.set_custom_bit(bit + (1 - (bit % 2)))
884 fn set_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
888 self.set_bit(bit, true)
891 fn set_bit(&mut self, bit: usize, custom: bool) -> Result<(), ()> {
892 let byte_offset = bit / 8;
893 let mask = 1 << (bit - 8 * byte_offset);
894 if byte_offset < T::KNOWN_FEATURE_MASK.len() && custom {
895 if (T::KNOWN_FEATURE_MASK[byte_offset] & mask) != 0 {
900 if self.flags.len() <= byte_offset {
901 self.flags.resize(byte_offset + 1, 0u8);
904 self.flags[byte_offset] |= mask;
910 impl<T: sealed::UpfrontShutdownScript> Features<T> {
912 pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
913 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
918 impl<T: sealed::ShutdownAnySegwit> Features<T> {
920 pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
921 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
926 impl<T: sealed::Wumbo> Features<T> {
928 pub(crate) fn clear_wumbo(mut self) -> Self {
929 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
934 impl<T: sealed::SCIDPrivacy> Features<T> {
935 pub(crate) fn clear_scid_privacy(&mut self) {
936 <T as sealed::SCIDPrivacy>::clear_bits(&mut self.flags);
940 impl<T: sealed::AnchorsZeroFeeHtlcTx> Features<T> {
941 pub(crate) fn clear_anchors_zero_fee_htlc_tx(&mut self) {
942 <T as sealed::AnchorsZeroFeeHtlcTx>::clear_bits(&mut self.flags);
946 impl<T: sealed::RouteBlinding> Features<T> {
948 pub(crate) fn clear_route_blinding(&mut self) {
949 <T as sealed::RouteBlinding>::clear_bits(&mut self.flags);
954 impl<T: sealed::UnknownFeature> Features<T> {
955 pub(crate) fn unknown() -> Self {
956 let mut features = Self::empty();
957 features.set_unknown_feature_required();
962 macro_rules! impl_feature_len_prefixed_write {
963 ($features: ident) => {
964 impl Writeable for $features {
965 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
966 (self.flags.len() as u16).write(w)?;
970 impl Readable for $features {
971 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
972 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
977 impl_feature_len_prefixed_write!(InitFeatures);
978 impl_feature_len_prefixed_write!(ChannelFeatures);
979 impl_feature_len_prefixed_write!(NodeFeatures);
980 impl_feature_len_prefixed_write!(Bolt11InvoiceFeatures);
981 impl_feature_len_prefixed_write!(Bolt12InvoiceFeatures);
982 impl_feature_len_prefixed_write!(BlindedHopFeatures);
984 // Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
985 macro_rules! impl_feature_tlv_write {
986 ($features: ident) => {
987 impl Writeable for $features {
988 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
989 WithoutLength(self).write(w)
992 impl Readable for $features {
993 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
994 Ok(WithoutLength::<Self>::read(r)?.0)
1000 impl_feature_tlv_write!(ChannelTypeFeatures);
1002 // Some features may appear both in a TLV record and as part of a TLV subtype sequence. The latter
1003 // requires a length but the former does not.
1005 impl<T: sealed::Context> Writeable for WithoutLength<&Features<T>> {
1006 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
1011 impl<T: sealed::Context> Readable for WithoutLength<Features<T>> {
1012 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
1013 let v = io_extras::read_to_end(r)?;
1014 Ok(WithoutLength(Features::<T>::from_be_bytes(v)))
1020 use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, Bolt11InvoiceFeatures, NodeFeatures, OfferFeatures, sealed};
1021 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
1022 use crate::util::ser::{Readable, WithoutLength, Writeable};
1025 fn sanity_test_unknown_bits() {
1026 let features = ChannelFeatures::empty();
1027 assert!(!features.requires_unknown_bits());
1028 assert!(!features.supports_unknown_bits());
1030 let mut features = ChannelFeatures::empty();
1031 features.set_unknown_feature_required();
1032 assert!(features.requires_unknown_bits());
1033 assert!(features.supports_unknown_bits());
1035 let mut features = ChannelFeatures::empty();
1036 features.set_unknown_feature_optional();
1037 assert!(!features.requires_unknown_bits());
1038 assert!(features.supports_unknown_bits());
1042 fn requires_unknown_bits_from() {
1043 let mut features1 = InitFeatures::empty();
1044 let mut features2 = InitFeatures::empty();
1045 assert!(!features1.requires_unknown_bits_from(&features2));
1046 assert!(!features2.requires_unknown_bits_from(&features1));
1048 features1.set_data_loss_protect_required();
1049 assert!(features1.requires_unknown_bits_from(&features2));
1050 assert!(!features2.requires_unknown_bits_from(&features1));
1052 features2.set_data_loss_protect_optional();
1053 assert!(!features1.requires_unknown_bits_from(&features2));
1054 assert!(!features2.requires_unknown_bits_from(&features1));
1056 features2.set_gossip_queries_required();
1057 assert!(!features1.requires_unknown_bits_from(&features2));
1058 assert!(features2.requires_unknown_bits_from(&features1));
1060 features1.set_gossip_queries_optional();
1061 assert!(!features1.requires_unknown_bits_from(&features2));
1062 assert!(!features2.requires_unknown_bits_from(&features1));
1064 features1.set_variable_length_onion_required();
1065 assert!(features1.requires_unknown_bits_from(&features2));
1066 assert!(!features2.requires_unknown_bits_from(&features1));
1068 features2.set_variable_length_onion_optional();
1069 assert!(!features1.requires_unknown_bits_from(&features2));
1070 assert!(!features2.requires_unknown_bits_from(&features1));
1072 features1.set_basic_mpp_required();
1073 features2.set_wumbo_required();
1074 assert!(features1.requires_unknown_bits_from(&features2));
1075 assert!(features2.requires_unknown_bits_from(&features1));
1079 fn convert_to_context_with_relevant_flags() {
1080 let mut init_features = InitFeatures::empty();
1081 // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
1082 // converted as it's only relevant in an init context).
1083 init_features.set_initial_routing_sync_required();
1084 init_features.set_data_loss_protect_required();
1085 init_features.set_variable_length_onion_required();
1086 init_features.set_static_remote_key_required();
1087 init_features.set_payment_secret_required();
1088 init_features.set_basic_mpp_optional();
1089 init_features.set_wumbo_optional();
1090 init_features.set_anchors_zero_fee_htlc_tx_optional();
1091 init_features.set_route_blinding_optional();
1092 init_features.set_shutdown_any_segwit_optional();
1093 init_features.set_onion_messages_optional();
1094 init_features.set_channel_type_optional();
1095 init_features.set_scid_privacy_optional();
1096 init_features.set_zero_conf_optional();
1098 assert!(init_features.initial_routing_sync());
1099 assert!(!init_features.supports_upfront_shutdown_script());
1100 assert!(!init_features.supports_gossip_queries());
1102 let node_features: NodeFeatures = init_features.to_context();
1104 // Check that the flags are as expected:
1105 // - option_data_loss_protect (req)
1106 // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
1107 // - basic_mpp | wumbo | option_anchors_zero_fee_htlc_tx
1108 // - option_route_blinding | opt_shutdown_anysegwit
1110 // - option_channel_type | option_scid_alias
1111 // - option_zeroconf
1112 assert_eq!(node_features.flags.len(), 7);
1113 assert_eq!(node_features.flags[0], 0b00000001);
1114 assert_eq!(node_features.flags[1], 0b01010001);
1115 assert_eq!(node_features.flags[2], 0b10001010);
1116 assert_eq!(node_features.flags[3], 0b00001010);
1117 assert_eq!(node_features.flags[4], 0b10000000);
1118 assert_eq!(node_features.flags[5], 0b10100000);
1119 assert_eq!(node_features.flags[6], 0b00001000);
1122 // Check that cleared flags are kept blank when converting back:
1123 // - initial_routing_sync was not applicable to NodeContext
1124 // - upfront_shutdown_script was cleared before converting
1125 // - gossip_queries was cleared before converting
1126 let features: InitFeatures = node_features.to_context_internal();
1127 assert!(!features.initial_routing_sync());
1128 assert!(!features.supports_upfront_shutdown_script());
1129 assert!(!init_features.supports_gossip_queries());
1133 fn convert_to_context_with_unknown_flags() {
1134 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1135 assert!(<sealed::ChannelContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
1136 <sealed::Bolt11InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
1137 let mut channel_features = ChannelFeatures::empty();
1138 channel_features.set_unknown_feature_optional();
1139 assert!(channel_features.supports_unknown_bits());
1140 let invoice_features: Bolt11InvoiceFeatures = channel_features.to_context_internal();
1141 assert!(!invoice_features.supports_unknown_bits());
1145 fn set_feature_bits() {
1146 let mut features = Bolt11InvoiceFeatures::empty();
1147 features.set_basic_mpp_optional();
1148 features.set_payment_secret_required();
1149 assert!(features.supports_basic_mpp());
1150 assert!(!features.requires_basic_mpp());
1151 assert!(features.requires_payment_secret());
1152 assert!(features.supports_payment_secret());
1154 // Set flags manually
1155 let mut features = NodeFeatures::empty();
1156 assert!(features.set_optional_feature_bit(55).is_ok());
1157 assert!(features.supports_keysend());
1158 assert!(features.set_optional_feature_bit(255).is_ok());
1159 assert!(features.set_required_feature_bit(256).is_err());
1163 fn set_custom_bits() {
1164 let mut features = Bolt11InvoiceFeatures::empty();
1165 features.set_variable_length_onion_optional();
1166 assert_eq!(features.flags[1], 0b00000010);
1168 assert!(features.set_optional_custom_bit(255).is_err());
1169 assert!(features.set_required_custom_bit(256).is_ok());
1170 assert!(features.set_required_custom_bit(258).is_ok());
1171 assert_eq!(features.flags[31], 0b00000000);
1172 assert_eq!(features.flags[32], 0b00000101);
1174 let known_bit = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::EVEN_BIT;
1175 let byte_offset = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::BYTE_OFFSET;
1176 assert_eq!(byte_offset, 1);
1177 assert_eq!(features.flags[byte_offset], 0b00000010);
1178 assert!(features.set_required_custom_bit(known_bit).is_err());
1179 assert_eq!(features.flags[byte_offset], 0b00000010);
1181 let mut features = Bolt11InvoiceFeatures::empty();
1182 assert!(features.set_optional_custom_bit(256).is_ok());
1183 assert!(features.set_optional_custom_bit(259).is_ok());
1184 assert_eq!(features.flags[32], 0b00001010);
1186 let mut features = Bolt11InvoiceFeatures::empty();
1187 assert!(features.set_required_custom_bit(257).is_ok());
1188 assert!(features.set_required_custom_bit(258).is_ok());
1189 assert_eq!(features.flags[32], 0b00000101);
1193 fn encodes_features_without_length() {
1194 let features = OfferFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1195 assert_eq!(features.flags.len(), 8);
1197 let mut serialized_features = Vec::new();
1198 WithoutLength(&features).write(&mut serialized_features).unwrap();
1199 assert_eq!(serialized_features.len(), 8);
1201 let deserialized_features =
1202 WithoutLength::<OfferFeatures>::read(&mut &serialized_features[..]).unwrap().0;
1203 assert_eq!(features, deserialized_features);
1207 fn invoice_features_encoding() {
1208 let features_as_u5s = vec![
1209 u5::try_from_u8(6).unwrap(),
1210 u5::try_from_u8(10).unwrap(),
1211 u5::try_from_u8(25).unwrap(),
1212 u5::try_from_u8(1).unwrap(),
1213 u5::try_from_u8(10).unwrap(),
1214 u5::try_from_u8(0).unwrap(),
1215 u5::try_from_u8(20).unwrap(),
1216 u5::try_from_u8(2).unwrap(),
1217 u5::try_from_u8(0).unwrap(),
1218 u5::try_from_u8(6).unwrap(),
1219 u5::try_from_u8(0).unwrap(),
1220 u5::try_from_u8(16).unwrap(),
1221 u5::try_from_u8(1).unwrap(),
1223 let features = Bolt11InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1225 // Test length calculation.
1226 assert_eq!(features.base32_len(), 13);
1228 // Test serialization.
1229 let features_serialized = features.to_base32();
1230 assert_eq!(features_as_u5s, features_serialized);
1232 // Test deserialization.
1233 let features_deserialized = Bolt11InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1234 assert_eq!(features, features_deserialized);
1238 fn test_channel_type_mapping() {
1239 // If we map an Bolt11InvoiceFeatures with StaticRemoteKey optional, it should map into a
1240 // required-StaticRemoteKey ChannelTypeFeatures.
1241 let mut init_features = InitFeatures::empty();
1242 init_features.set_static_remote_key_optional();
1243 let converted_features = ChannelTypeFeatures::from_init(&init_features);
1244 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1245 assert!(!converted_features.supports_any_optional_bits());
1246 assert!(converted_features.requires_static_remote_key());
1250 #[cfg(feature = "std")]
1251 fn test_excess_zero_bytes_ignored() {
1252 // Checks that `Hash` and `PartialEq` ignore excess zero bytes, which may appear due to
1253 // feature conversion or because a peer serialized their feature poorly.
1254 use std::collections::hash_map::DefaultHasher;
1255 use std::hash::{Hash, Hasher};
1257 let mut zerod_features = InitFeatures::empty();
1258 zerod_features.flags = vec![0];
1259 let empty_features = InitFeatures::empty();
1260 assert!(empty_features.flags.is_empty());
1262 assert_eq!(zerod_features, empty_features);
1264 let mut zerod_hash = DefaultHasher::new();
1265 zerod_features.hash(&mut zerod_hash);
1266 let mut empty_hash = DefaultHasher::new();
1267 empty_features.hash(&mut empty_hash);
1268 assert_eq!(zerod_hash.finish(), empty_hash.finish());