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).
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).
76 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
77 //! [messages]: crate::ln::msgs
79 use crate::{io, io_extras};
80 use crate::prelude::*;
82 use core::borrow::Borrow;
83 use core::hash::{Hash, Hasher};
84 use core::marker::PhantomData;
87 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
88 use crate::ln::msgs::DecodeError;
89 use crate::util::ser::{Readable, WithoutLength, Writeable, Writer};
92 use crate::prelude::*;
93 use crate::ln::features::Features;
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.
99 /// Bitmask for selecting features that are known to the implementation.
100 const KNOWN_FEATURE_MASK: &'static [u8];
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 {}
111 impl Context for $context {
112 const KNOWN_FEATURE_MASK: &'static [u8] = &[
115 <Self as $known_feature>::REQUIRED_MASK |
116 <Self as $known_feature>::OPTIONAL_MASK)*,
121 impl alloc::fmt::Display for Features<$context> {
122 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
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" }))?;
130 {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
132 fmt.write_fmt(format_args!("unknown flags: {}",
133 if self.requires_unknown_bits() { "required" }
134 else if self.supports_unknown_bits() { "supported" } else { "none" }))
140 define_context!(InitContext, [
142 DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
144 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
146 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
148 RouteBlinding | ShutdownAnySegwit | Taproot,
152 ChannelType | SCIDPrivacy,
156 define_context!(NodeContext, [
158 DataLossProtect | UpfrontShutdownScript | GossipQueries,
160 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
162 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
164 RouteBlinding | ShutdownAnySegwit | Taproot,
168 ChannelType | SCIDPrivacy,
172 define_context!(ChannelContext, []);
173 define_context!(Bolt11InvoiceContext, [
177 VariableLengthOnion | PaymentSecret,
189 define_context!(OfferContext, []);
190 define_context!(InvoiceRequestContext, []);
191 define_context!(Bolt12InvoiceContext, [
199 define_context!(BlindedHopContext, []);
200 // This isn't a "real" feature context, and is only used in the channel_type field in an
201 // `OpenChannel` message.
202 define_context!(ChannelTypeContext, [
208 AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
219 /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
220 /// useful for manipulating feature flags.
221 macro_rules! define_feature {
222 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
223 $required_setter: ident, $supported_getter: ident) => {
226 /// See [BOLT #9] for details.
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;
233 /// The bit used to signify that the feature is optional.
234 const ODD_BIT: usize = $odd_bit;
236 /// Assertion that [`EVEN_BIT`] is actually even.
238 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
239 const ASSERT_EVEN_BIT_PARITY: usize;
241 /// Assertion that [`ODD_BIT`] is actually odd.
243 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
244 const ASSERT_ODD_BIT_PARITY: usize;
246 /// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
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;
252 /// The byte where the feature is set.
253 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
255 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
257 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
258 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
260 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
262 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
263 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
265 /// Returns whether the feature is required by the given flags.
267 fn requires_feature(flags: &Vec<u8>) -> bool {
268 flags.len() > Self::BYTE_OFFSET &&
269 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
272 /// Returns whether the feature is supported by the given flags.
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
279 /// Sets the feature's required (even) bit in the given flags.
281 fn set_required_bit(flags: &mut Vec<u8>) {
282 if flags.len() <= Self::BYTE_OFFSET {
283 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
286 flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
287 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
290 /// Sets the feature's optional (odd) bit in the given flags.
292 fn set_optional_bit(flags: &mut Vec<u8>) {
293 if flags.len() <= Self::BYTE_OFFSET {
294 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
297 flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
300 /// Clears the feature's required (even) and optional (odd) bits from the given
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;
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);
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);
321 /// Set this feature as required.
322 pub fn $required_setter(&mut self) {
323 <T as $feature>::set_required_bit(&mut self.flags);
326 /// Checks if this feature is supported.
327 pub fn $supported_getter(&self) -> bool {
328 <T as $feature>::supports_feature(&self.flags)
333 impl $feature for $context {
335 const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
338 const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
340 // (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
341 #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
342 const ASSERT_BITS_IN_MASK: u8 =
343 ((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
344 >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
348 ($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)
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!
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);
432 /// Tracks the set of features which a node implements, templated by the context in which it
435 /// This is not exported to bindings users as we map the concrete feature types below directly instead
437 pub struct Features<T: sealed::Context> {
438 /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
440 mark: PhantomData<T>,
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()) {
453 impl<T: sealed::Context> core::ops::BitOr for Features<T> {
456 fn bitor(mut self, o: Self) -> Self {
462 impl<T: sealed::Context> Clone for Features<T> {
463 fn clone(&self) -> Self {
465 flags: self.flags.clone(),
470 impl<T: sealed::Context> Hash for Features<T> {
471 fn hash<H: Hasher>(&self, hasher: &mut H) {
472 self.flags.hash(hasher);
475 impl<T: sealed::Context> PartialEq for Features<T> {
476 fn eq(&self, o: &Self) -> bool {
477 self.flags.eq(&o.flags)
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)
485 impl<T: sealed::Context + Eq> Ord for Features<T> {
486 fn cmp(&self, other: &Self) -> cmp::Ordering {
487 self.flags.cmp(&other.flags)
490 impl<T: sealed::Context> fmt::Debug for Features<T> {
491 fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
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>;
513 /// Features used within the channel_type field in an OpenChannel message.
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.
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.
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>;
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() {
532 self.flags[i].write(w)?;
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)?;
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()
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()
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`].
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.
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();
571 res.set_basic_mpp_optional();
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()
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;
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);
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);
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();
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();
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();
637 // Trim the highest feature bits.
638 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
641 writer.write(&res_u5s)
645 impl Base32Len for Bolt11InvoiceFeatures {
646 fn base32_len(&self) -> usize {
647 self.to_base32().len()
651 impl FromBase32 for Bolt11InvoiceFeatures {
652 type Err = bech32::Error;
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;
669 // Trim the highest feature bits.
670 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
673 Ok(Bolt11InvoiceFeatures::from_le_bytes(res_bytes))
677 impl<T: sealed::Context> Features<T> {
678 /// Create a blank Features with no features set
679 pub fn empty() -> Self {
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);
699 Features::<C> { flags, mark: PhantomData, }
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.
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> {
714 /// Gets the underlying flags set, in LE.
715 pub fn le_flags(&self) -> &Vec<u8> {
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
726 /// Create a [`Features`] given a set of flags, in big-endian. This is in byte order from
727 /// most on-the-wire encodings.
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
738 pub(crate) fn supports_any_optional_bits(&self) -> bool {
739 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
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
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`
752 | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
753 | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
757 (byte & (REQUIRED_FEATURES & unknown_features)) != 0
761 /// Returns true if this `Features` object contains unknown feature flags which are set as
763 pub fn requires_unknown_bits(&self) -> bool {
764 // Bitwise AND-ing with all even bits set except for known features will select required
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]
774 (byte & (required_features & unknown_features)) != 0
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]
788 (byte & unknown_features) != 0
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.
802 // `self` has a non-zero byte that `other` doesn't.
810 /// Sets a required feature bit. Errors if `bit` is outside the feature range as defined
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`).
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))
821 /// Sets an optional feature bit. Errors if `bit` is outside the feature range as defined
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`).
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)))
832 fn set_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
836 self.set_bit(bit, false)
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.
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`).
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))
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.
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`).
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)))
861 fn set_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
865 self.set_bit(bit, true)
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 {
877 if self.flags.len() <= byte_offset {
878 self.flags.resize(byte_offset + 1, 0u8);
881 self.flags[byte_offset] |= mask;
887 impl<T: sealed::UpfrontShutdownScript> Features<T> {
889 pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
890 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
895 impl<T: sealed::ShutdownAnySegwit> Features<T> {
897 pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
898 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
903 impl<T: sealed::Wumbo> Features<T> {
905 pub(crate) fn clear_wumbo(mut self) -> Self {
906 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
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);
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);
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();
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)?;
940 impl Readable for $features {
941 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
942 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
947 impl_feature_len_prefixed_write!(InitFeatures);
948 impl_feature_len_prefixed_write!(ChannelFeatures);
949 impl_feature_len_prefixed_write!(NodeFeatures);
950 impl_feature_len_prefixed_write!(Bolt11InvoiceFeatures);
951 impl_feature_len_prefixed_write!(Bolt12InvoiceFeatures);
952 impl_feature_len_prefixed_write!(BlindedHopFeatures);
954 // Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
955 macro_rules! impl_feature_tlv_write {
956 ($features: ident) => {
957 impl Writeable for $features {
958 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
959 WithoutLength(self).write(w)
962 impl Readable for $features {
963 fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
964 Ok(WithoutLength::<Self>::read(r)?.0)
970 impl_feature_tlv_write!(ChannelTypeFeatures);
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.
975 impl<T: sealed::Context> Writeable for WithoutLength<&Features<T>> {
976 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
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)))
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};
995 fn sanity_test_unknown_bits() {
996 let features = ChannelFeatures::empty();
997 assert!(!features.requires_unknown_bits());
998 assert!(!features.supports_unknown_bits());
1000 let mut features = ChannelFeatures::empty();
1001 features.set_unknown_feature_required();
1002 assert!(features.requires_unknown_bits());
1003 assert!(features.supports_unknown_bits());
1005 let mut features = ChannelFeatures::empty();
1006 features.set_unknown_feature_optional();
1007 assert!(!features.requires_unknown_bits());
1008 assert!(features.supports_unknown_bits());
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));
1018 features1.set_data_loss_protect_required();
1019 assert!(features1.requires_unknown_bits_from(&features2));
1020 assert!(!features2.requires_unknown_bits_from(&features1));
1022 features2.set_data_loss_protect_optional();
1023 assert!(!features1.requires_unknown_bits_from(&features2));
1024 assert!(!features2.requires_unknown_bits_from(&features1));
1026 features2.set_gossip_queries_required();
1027 assert!(!features1.requires_unknown_bits_from(&features2));
1028 assert!(features2.requires_unknown_bits_from(&features1));
1030 features1.set_gossip_queries_optional();
1031 assert!(!features1.requires_unknown_bits_from(&features2));
1032 assert!(!features2.requires_unknown_bits_from(&features1));
1034 features1.set_variable_length_onion_required();
1035 assert!(features1.requires_unknown_bits_from(&features2));
1036 assert!(!features2.requires_unknown_bits_from(&features1));
1038 features2.set_variable_length_onion_optional();
1039 assert!(!features1.requires_unknown_bits_from(&features2));
1040 assert!(!features2.requires_unknown_bits_from(&features1));
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));
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();
1068 assert!(init_features.initial_routing_sync());
1069 assert!(!init_features.supports_upfront_shutdown_script());
1070 assert!(!init_features.supports_gossip_queries());
1072 let node_features: NodeFeatures = init_features.to_context();
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
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);
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());
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());
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());
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());
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);
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);
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);
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);
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);
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);
1167 let mut serialized_features = Vec::new();
1168 WithoutLength(&features).write(&mut serialized_features).unwrap();
1169 assert_eq!(serialized_features.len(), 8);
1171 let deserialized_features =
1172 WithoutLength::<OfferFeatures>::read(&mut &serialized_features[..]).unwrap().0;
1173 assert_eq!(features, deserialized_features);
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(),
1193 let features = Bolt11InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1195 // Test length calculation.
1196 assert_eq!(features.base32_len(), 13);
1198 // Test serialization.
1199 let features_serialized = features.to_base32();
1200 assert_eq!(features_as_u5s, features_serialized);
1202 // Test deserialization.
1203 let features_deserialized = Bolt11InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1204 assert_eq!(features, features_deserialized);
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());