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Adapt intro node process_pending_htlcs test for non-intro nodes
[rust-lightning] / lightning / src / ln / features.rs
1 // This file is Copyright its original authors, visible in version control
2 // history.
3 //
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
8 // licenses.
9
10 //! Feature flag definitions for the Lightning protocol according to [BOLT #9].
11 //!
12 //! Lightning nodes advertise a supported set of operation through feature flags. Features are
13 //! applicable for a specific context as indicated in some [messages]. [`Features`] encapsulates
14 //! behavior for specifying and checking feature flags for a particular context. Each feature is
15 //! defined internally by a trait specifying the corresponding flags (i.e., even and odd bits).
16 //!
17 //! Whether a feature is considered "known" or "unknown" is relative to the implementation, whereas
18 //! the term "supports" is used in reference to a particular set of [`Features`]. That is, a node
19 //! supports a feature if it advertises the feature (as either required or optional) to its peers.
20 //! And the implementation can interpret a feature if the feature is known to it.
21 //!
22 //! The following features are currently required in the LDK:
23 //! - `VariableLengthOnion` - requires/supports variable-length routing onion payloads
24 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md) for more information).
25 //! - `StaticRemoteKey` - requires/supports static key for remote output
26 //!     (see [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more information).
27 //!
28 //! The following features are currently supported in the LDK:
29 //! - `DataLossProtect` - requires/supports that a node which has somehow fallen behind, e.g., has been restored from an old backup,
30 //!     can detect that it has fallen behind
31 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
32 //! - `InitialRoutingSync` - requires/supports that the sending node needs a complete routing information dump
33 //!     (see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#initial-sync) for more information).
34 //! - `UpfrontShutdownScript` - commits to a shutdown scriptpubkey when opening a channel
35 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-open_channel-message) for more information).
36 //! - `GossipQueries` - requires/supports more sophisticated gossip control
37 //!     (see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md) for more information).
38 //! - `PaymentSecret` - requires/supports that a node supports payment_secret field
39 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md) for more information).
40 //! - `BasicMPP` - requires/supports that a node can receive basic multi-part payments
41 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md#basic-multi-part-payments) for more information).
42 //! - `Wumbo` - requires/supports that a node create large channels. Called `option_support_large_channel` in the spec.
43 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-open_channel-message) for more information).
44 //! - `AnchorsZeroFeeHtlcTx` - requires/supports that commitment transactions include anchor outputs
45 //!     and HTLC transactions are pre-signed with zero fee (see
46 //!     [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more
47 //!     information).
48 //! - `RouteBlinding` - requires/supports that a node can relay payments over blinded paths
49 //!     (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md#route-blinding) for more information).
50 //! - `ShutdownAnySegwit` - requires/supports that future segwit versions are allowed in `shutdown`
51 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
52 //! - `OnionMessages` - requires/supports forwarding onion messages
53 //!     (see [BOLT-7](https://github.com/lightning/bolts/pull/759/files) for more information).
54 //     TODO: update link
55 //! - `ChannelType` - node supports the channel_type field in open/accept
56 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
57 //! - `SCIDPrivacy` - supply channel aliases for routing
58 //!     (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
59 //! - `PaymentMetadata` - include additional data in invoices which is passed to recipients in the
60 //!      onion.
61 //!      (see [BOLT-11](https://github.com/lightning/bolts/blob/master/11-payment-encoding.md) for
62 //!      more).
63 //! - `ZeroConf` - supports accepting HTLCs and using channels prior to funding confirmation
64 //!      (see
65 //!      [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-channel_ready-message)
66 //!      for more info).
67 //! - `Keysend` - send funds to a node without an invoice
68 //!     (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
69 //!
70 //! LDK knows about the following features, but does not support them:
71 //! - `AnchorsNonzeroFeeHtlcTx` - the initial version of anchor outputs, which was later found to be
72 //!     vulnerable (see this
73 //!     [mailing list post](https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-September/002796.html)
74 //!     for more information).
75 //!
76 //! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
77 //! [messages]: crate::ln::msgs
78
79 use crate::{io, io_extras};
80 use crate::prelude::*;
81 use core::{cmp, fmt};
82 use core::borrow::Borrow;
83 use core::hash::{Hash, Hasher};
84 use core::marker::PhantomData;
85
86 use bitcoin::bech32;
87 use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
88 use crate::ln::msgs::DecodeError;
89 use crate::util::ser::{Readable, WithoutLength, Writeable, Writer};
90
91 mod sealed {
92         use crate::prelude::*;
93         use crate::ln::features::Features;
94
95         /// The context in which [`Features`] are applicable. Defines which features are known to the
96         /// implementation, though specification of them as required or optional is up to the code
97         /// constructing a features object.
98         pub trait Context {
99                 /// Bitmask for selecting features that are known to the implementation.
100                 const KNOWN_FEATURE_MASK: &'static [u8];
101         }
102
103         /// Defines a [`Context`] by stating which features it requires and which are optional. Features
104         /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
105         /// feature identifiers.
106         macro_rules! define_context {
107                 ($context: ident, [$( $( $known_feature: ident )|*, )*]) => {
108                         #[derive(Eq, PartialEq)]
109                         pub struct $context {}
110
111                         impl Context for $context {
112                                 const KNOWN_FEATURE_MASK: &'static [u8] = &[
113                                         $(
114                                                 0b00_00_00_00 $(|
115                                                         <Self as $known_feature>::REQUIRED_MASK |
116                                                         <Self as $known_feature>::OPTIONAL_MASK)*,
117                                         )*
118                                 ];
119                         }
120
121                         impl alloc::fmt::Display for Features<$context> {
122                                 fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
123                                         $(
124                                                 $(
125                                                         fmt.write_fmt(format_args!("{}: {}, ", stringify!($known_feature),
126                                                                 if <$context as $known_feature>::requires_feature(&self.flags) { "required" }
127                                                                 else if <$context as $known_feature>::supports_feature(&self.flags) { "supported" }
128                                                                 else { "not supported" }))?;
129                                                 )*
130                                                 {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
131                                         )*
132                                         fmt.write_fmt(format_args!("unknown flags: {}",
133                                                 if self.requires_unknown_bits() { "required" }
134                                                 else if self.supports_unknown_bits() { "supported" } else { "none" }))
135                                 }
136                         }
137                 };
138         }
139
140         define_context!(InitContext, [
141                 // Byte 0
142                 DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
143                 // Byte 1
144                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
145                 // Byte 2
146                 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
147                 // Byte 3
148                 RouteBlinding | ShutdownAnySegwit | Taproot,
149                 // Byte 4
150                 OnionMessages,
151                 // Byte 5
152                 ChannelType | SCIDPrivacy,
153                 // Byte 6
154                 ZeroConf,
155         ]);
156         define_context!(NodeContext, [
157                 // Byte 0
158                 DataLossProtect | UpfrontShutdownScript | GossipQueries,
159                 // Byte 1
160                 VariableLengthOnion | StaticRemoteKey | PaymentSecret,
161                 // Byte 2
162                 BasicMPP | Wumbo | AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
163                 // Byte 3
164                 RouteBlinding | ShutdownAnySegwit | Taproot,
165                 // Byte 4
166                 OnionMessages,
167                 // Byte 5
168                 ChannelType | SCIDPrivacy,
169                 // Byte 6
170                 ZeroConf | Keysend,
171         ]);
172         define_context!(ChannelContext, []);
173         define_context!(Bolt11InvoiceContext, [
174                 // Byte 0
175                 ,
176                 // Byte 1
177                 VariableLengthOnion | PaymentSecret,
178                 // Byte 2
179                 BasicMPP,
180                 // Byte 3
181                 ,
182                 // Byte 4
183                 ,
184                 // Byte 5
185                 ,
186                 // Byte 6
187                 PaymentMetadata,
188         ]);
189         define_context!(OfferContext, []);
190         define_context!(InvoiceRequestContext, []);
191         define_context!(Bolt12InvoiceContext, [
192                 // Byte 0
193                 ,
194                 // Byte 1
195                 ,
196                 // Byte 2
197                 BasicMPP,
198         ]);
199         define_context!(BlindedHopContext, []);
200         // This isn't a "real" feature context, and is only used in the channel_type field in an
201         // `OpenChannel` message.
202         define_context!(ChannelTypeContext, [
203                 // Byte 0
204                 ,
205                 // Byte 1
206                 StaticRemoteKey,
207                 // Byte 2
208                 AnchorsNonzeroFeeHtlcTx | AnchorsZeroFeeHtlcTx,
209                 // Byte 3
210                 Taproot,
211                 // Byte 4
212                 ,
213                 // Byte 5
214                 SCIDPrivacy,
215                 // Byte 6
216                 ZeroConf,
217         ]);
218
219         /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
220         /// useful for manipulating feature flags.
221         macro_rules! define_feature {
222                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
223                  $required_setter: ident, $supported_getter: ident) => {
224                         #[doc = $doc]
225                         ///
226                         /// See [BOLT #9] for details.
227                         ///
228                         /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
229                         pub trait $feature: Context {
230                                 /// The bit used to signify that the feature is required.
231                                 const EVEN_BIT: usize = $odd_bit - 1;
232
233                                 /// The bit used to signify that the feature is optional.
234                                 const ODD_BIT: usize = $odd_bit;
235
236                                 /// Assertion that [`EVEN_BIT`] is actually even.
237                                 ///
238                                 /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
239                                 const ASSERT_EVEN_BIT_PARITY: usize;
240
241                                 /// Assertion that [`ODD_BIT`] is actually odd.
242                                 ///
243                                 /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
244                                 const ASSERT_ODD_BIT_PARITY: usize;
245
246                                 /// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
247                                 ///
248                                 /// [`KNOWN_FEATURE_MASK`]: Context::KNOWN_FEATURE_MASK
249                                 #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
250                                 const ASSERT_BITS_IN_MASK: u8;
251
252                                 /// The byte where the feature is set.
253                                 const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
254
255                                 /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
256                                 ///
257                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
258                                 const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
259
260                                 /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
261                                 ///
262                                 /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
263                                 const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
264
265                                 /// Returns whether the feature is required by the given flags.
266                                 #[inline]
267                                 fn requires_feature(flags: &Vec<u8>) -> bool {
268                                         flags.len() > Self::BYTE_OFFSET &&
269                                                 (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
270                                 }
271
272                                 /// Returns whether the feature is supported by the given flags.
273                                 #[inline]
274                                 fn supports_feature(flags: &Vec<u8>) -> bool {
275                                         flags.len() > Self::BYTE_OFFSET &&
276                                                 (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
277                                 }
278
279                                 /// Sets the feature's required (even) bit in the given flags.
280                                 #[inline]
281                                 fn set_required_bit(flags: &mut Vec<u8>) {
282                                         if flags.len() <= Self::BYTE_OFFSET {
283                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
284                                         }
285
286                                         flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
287                                         flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
288                                 }
289
290                                 /// Sets the feature's optional (odd) bit in the given flags.
291                                 #[inline]
292                                 fn set_optional_bit(flags: &mut Vec<u8>) {
293                                         if flags.len() <= Self::BYTE_OFFSET {
294                                                 flags.resize(Self::BYTE_OFFSET + 1, 0u8);
295                                         }
296
297                                         flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
298                                 }
299
300                                 /// Clears the feature's required (even) and optional (odd) bits from the given
301                                 /// flags.
302                                 #[inline]
303                                 fn clear_bits(flags: &mut Vec<u8>) {
304                                         if flags.len() > Self::BYTE_OFFSET {
305                                                 flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
306                                                 flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
307                                         }
308
309                                         let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
310                                         let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
311                                         flags.resize(size, 0u8);
312                                 }
313                         }
314
315                         impl <T: $feature> Features<T> {
316                                 /// Set this feature as optional.
317                                 pub fn $optional_setter(&mut self) {
318                                         <T as $feature>::set_optional_bit(&mut self.flags);
319                                 }
320
321                                 /// Set this feature as required.
322                                 pub fn $required_setter(&mut self) {
323                                         <T as $feature>::set_required_bit(&mut self.flags);
324                                 }
325
326                                 /// Checks if this feature is supported.
327                                 pub fn $supported_getter(&self) -> bool {
328                                         <T as $feature>::supports_feature(&self.flags)
329                                 }
330                         }
331
332                         $(
333                                 impl $feature for $context {
334                                         // EVEN_BIT % 2 == 0
335                                         const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
336
337                                         // ODD_BIT % 2 == 1
338                                         const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
339
340                                         // (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
341                                         #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
342                                         const ASSERT_BITS_IN_MASK: u8 =
343                                                 ((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
344                                                  >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
345                                 }
346                         )*
347                 };
348                 ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
349                  $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
350                         define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
351                         impl <T: $feature> Features<T> {
352                                 /// Checks if this feature is required.
353                                 pub fn $required_getter(&self) -> bool {
354                                         <T as $feature>::requires_feature(&self.flags)
355                                 }
356                         }
357                 }
358         }
359
360         define_feature!(1, DataLossProtect, [InitContext, NodeContext],
361                 "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
362                 set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
363         // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
364         define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
365                 set_initial_routing_sync_optional, set_initial_routing_sync_required,
366                 initial_routing_sync);
367         define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
368                 "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
369                 set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
370                 requires_upfront_shutdown_script);
371         define_feature!(7, GossipQueries, [InitContext, NodeContext],
372                 "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
373                 supports_gossip_queries, requires_gossip_queries);
374         define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, Bolt11InvoiceContext],
375                 "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
376                 set_variable_length_onion_required, supports_variable_length_onion,
377                 requires_variable_length_onion);
378         define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
379                 "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
380                 set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
381         define_feature!(15, PaymentSecret, [InitContext, NodeContext, Bolt11InvoiceContext],
382                 "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
383                 supports_payment_secret, requires_payment_secret);
384         define_feature!(17, BasicMPP, [InitContext, NodeContext, Bolt11InvoiceContext, Bolt12InvoiceContext],
385                 "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
386                 supports_basic_mpp, requires_basic_mpp);
387         define_feature!(19, Wumbo, [InitContext, NodeContext],
388                 "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
389                 supports_wumbo, requires_wumbo);
390         define_feature!(21, AnchorsNonzeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
391                 "Feature flags for `option_anchors_nonzero_fee_htlc_tx`.", set_anchors_nonzero_fee_htlc_tx_optional,
392                 set_anchors_nonzero_fee_htlc_tx_required, supports_anchors_nonzero_fee_htlc_tx, requires_anchors_nonzero_fee_htlc_tx);
393         define_feature!(23, AnchorsZeroFeeHtlcTx, [InitContext, NodeContext, ChannelTypeContext],
394                 "Feature flags for `option_anchors_zero_fee_htlc_tx`.", set_anchors_zero_fee_htlc_tx_optional,
395                 set_anchors_zero_fee_htlc_tx_required, supports_anchors_zero_fee_htlc_tx, requires_anchors_zero_fee_htlc_tx);
396         define_feature!(25, RouteBlinding, [InitContext, NodeContext],
397                 "Feature flags for `option_route_blinding`.", set_route_blinding_optional,
398                 set_route_blinding_required, supports_route_blinding, requires_route_blinding);
399         define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
400                 "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
401                 set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
402         define_feature!(31, Taproot, [InitContext, NodeContext, ChannelTypeContext],
403                 "Feature flags for `option_taproot`.", set_taproot_optional,
404                 set_taproot_required, supports_taproot, requires_taproot);
405         define_feature!(39, OnionMessages, [InitContext, NodeContext],
406                 "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
407                 set_onion_messages_required, supports_onion_messages, requires_onion_messages);
408         define_feature!(45, ChannelType, [InitContext, NodeContext],
409                 "Feature flags for `option_channel_type`.", set_channel_type_optional,
410                 set_channel_type_required, supports_channel_type, requires_channel_type);
411         define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
412                 "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
413                 set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
414         define_feature!(49, PaymentMetadata, [Bolt11InvoiceContext],
415                 "Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
416                 set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
417         define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
418                 "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
419                 set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
420         define_feature!(55, Keysend, [NodeContext],
421                 "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
422                 supports_keysend, requires_keysend);
423         // Note: update the module-level docs when a new feature bit is added!
424
425         #[cfg(test)]
426         define_feature!(123456789, UnknownFeature,
427                 [NodeContext, ChannelContext, Bolt11InvoiceContext, OfferContext, InvoiceRequestContext, Bolt12InvoiceContext, BlindedHopContext],
428                 "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
429                 set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
430 }
431
432 /// Tracks the set of features which a node implements, templated by the context in which it
433 /// appears.
434 ///
435 /// This is not exported to bindings users as we map the concrete feature types below directly instead
436 #[derive(Eq)]
437 pub struct Features<T: sealed::Context> {
438         /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
439         flags: Vec<u8>,
440         mark: PhantomData<T>,
441 }
442
443 impl<T: sealed::Context, Rhs: Borrow<Self>> core::ops::BitOrAssign<Rhs> for Features<T> {
444         fn bitor_assign(&mut self, rhs: Rhs) {
445                 let total_feature_len = cmp::max(self.flags.len(), rhs.borrow().flags.len());
446                 self.flags.resize(total_feature_len, 0u8);
447                 for (byte, rhs_byte) in self.flags.iter_mut().zip(rhs.borrow().flags.iter()) {
448                         *byte |= *rhs_byte;
449                 }
450         }
451 }
452
453 impl<T: sealed::Context> core::ops::BitOr for Features<T> {
454         type Output = Self;
455
456         fn bitor(mut self, o: Self) -> Self {
457                 self |= o;
458                 self
459         }
460 }
461
462 impl<T: sealed::Context> Clone for Features<T> {
463         fn clone(&self) -> Self {
464                 Self {
465                         flags: self.flags.clone(),
466                         mark: PhantomData,
467                 }
468         }
469 }
470 impl<T: sealed::Context> Hash for Features<T> {
471         fn hash<H: Hasher>(&self, hasher: &mut H) {
472                 let mut nonzero_flags = &self.flags[..];
473                 while nonzero_flags.last() == Some(&0) {
474                         nonzero_flags = &nonzero_flags[..nonzero_flags.len() - 1];
475                 }
476                 nonzero_flags.hash(hasher);
477         }
478 }
479 impl<T: sealed::Context> PartialEq for Features<T> {
480         fn eq(&self, o: &Self) -> bool {
481                 let mut o_iter = o.flags.iter();
482                 let mut self_iter = self.flags.iter();
483                 loop {
484                         match (o_iter.next(), self_iter.next()) {
485                                 (Some(o), Some(us)) => if o != us { return false },
486                                 (Some(b), None) | (None, Some(b)) => if *b != 0 { return false },
487                                 (None, None) => return true,
488                         }
489                 }
490         }
491 }
492 impl<T: sealed::Context> PartialOrd for Features<T> {
493         fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
494                 self.flags.partial_cmp(&other.flags)
495         }
496 }
497 impl<T: sealed::Context + Eq> Ord for Features<T> {
498         fn cmp(&self, other: &Self) -> cmp::Ordering {
499                 self.flags.cmp(&other.flags)
500         }
501 }
502 impl<T: sealed::Context> fmt::Debug for Features<T> {
503         fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
504                 self.flags.fmt(fmt)
505         }
506 }
507
508 /// Features used within an `init` message.
509 pub type InitFeatures = Features<sealed::InitContext>;
510 /// Features used within a `node_announcement` message.
511 pub type NodeFeatures = Features<sealed::NodeContext>;
512 /// Features used within a `channel_announcement` message.
513 pub type ChannelFeatures = Features<sealed::ChannelContext>;
514 /// Features used within an invoice.
515 pub type Bolt11InvoiceFeatures = Features<sealed::Bolt11InvoiceContext>;
516 /// Features used within an `offer`.
517 pub type OfferFeatures = Features<sealed::OfferContext>;
518 /// Features used within an `invoice_request`.
519 pub type InvoiceRequestFeatures = Features<sealed::InvoiceRequestContext>;
520 /// Features used within an `invoice`.
521 pub type Bolt12InvoiceFeatures = Features<sealed::Bolt12InvoiceContext>;
522 /// Features used within BOLT 4 encrypted_data_tlv and BOLT 12 blinded_payinfo
523 pub type BlindedHopFeatures = Features<sealed::BlindedHopContext>;
524
525 /// Features used within the channel_type field in an OpenChannel message.
526 ///
527 /// A channel is always of some known "type", describing the transaction formats used and the exact
528 /// semantics of our interaction with our peer.
529 ///
530 /// Note that because a channel is a specific type which is proposed by the opener and accepted by
531 /// the counterparty, only required features are allowed here.
532 ///
533 /// This is serialized differently from other feature types - it is not prefixed by a length, and
534 /// thus must only appear inside a TLV where its length is known in advance.
535 pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
536
537 impl InitFeatures {
538         /// Writes all features present up to, and including, 13.
539         pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
540                 let len = cmp::min(2, self.flags.len());
541                 (len as u16).write(w)?;
542                 for i in (0..len).rev() {
543                         if i == 0 {
544                                 self.flags[i].write(w)?;
545                         } else {
546                                 // On byte 1, we want up-to-and-including-bit-13, 0-indexed, which is
547                                 // up-to-and-including-bit-5, 0-indexed, on this byte:
548                                 (self.flags[i] & 0b00_11_11_11).write(w)?;
549                         }
550                 }
551                 Ok(())
552         }
553
554         /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
555         /// are included in the result.
556         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
557                 self.to_context_internal()
558         }
559 }
560
561 impl Bolt11InvoiceFeatures {
562         /// Converts `Bolt11InvoiceFeatures` to `Features<C>`. Only known `Bolt11InvoiceFeatures` relevant to
563         /// context `C` are included in the result.
564         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
565                 self.to_context_internal()
566         }
567
568         /// Getting a route for a keysend payment to a private node requires providing the payee's
569         /// features (since they were not announced in a node announcement). However, keysend payments
570         /// don't have an invoice to pull the payee's features from, so this method is provided for use in
571         /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
572         /// `Bolt11InvoiceFeatures` for [`find_route`].
573         ///
574         /// MPP keysend is not widely supported yet, so we parameterize support to allow the user to
575         /// choose whether their router should find multi-part routes.
576         ///
577         /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
578         /// [`find_route`]: crate::routing::router::find_route
579         pub(crate) fn for_keysend(allow_mpp: bool) -> Bolt11InvoiceFeatures {
580                 let mut res = Bolt11InvoiceFeatures::empty();
581                 res.set_variable_length_onion_optional();
582                 if allow_mpp {
583                         res.set_basic_mpp_optional();
584                 }
585                 res
586         }
587 }
588
589 impl Bolt12InvoiceFeatures {
590         /// Converts [`Bolt12InvoiceFeatures`] to [`Features<C>`]. Only known [`Bolt12InvoiceFeatures`]
591         /// relevant to context `C` are included in the result.
592         pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
593                 self.to_context_internal()
594         }
595 }
596
597 impl ChannelTypeFeatures {
598         // Maps the relevant `InitFeatures` to `ChannelTypeFeatures`. Any unknown features to
599         // `ChannelTypeFeatures` are not included in the result.
600         pub(crate) fn from_init(init: &InitFeatures) -> Self {
601                 let mut ret = init.to_context_internal();
602                 // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
603                 // optional bits and then AND out the optional ones.
604                 for byte in ret.flags.iter_mut() {
605                         *byte |= (*byte & 0b10_10_10_10) >> 1;
606                         *byte &= 0b01_01_01_01;
607                 }
608                 ret
609         }
610
611         /// Constructs a ChannelTypeFeatures with only static_remotekey set
612         pub(crate) fn only_static_remote_key() -> Self {
613                 let mut ret = Self::empty();
614                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
615                 ret
616         }
617
618         /// Constructs a ChannelTypeFeatures with anchors support
619         pub(crate) fn anchors_zero_htlc_fee_and_dependencies() -> Self {
620                 let mut ret = Self::empty();
621                 <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
622                 <sealed::ChannelTypeContext as sealed::AnchorsZeroFeeHtlcTx>::set_required_bit(&mut ret.flags);
623                 ret
624         }
625 }
626
627 impl ToBase32 for Bolt11InvoiceFeatures {
628         fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
629                 // Explanation for the "4": the normal way to round up when dividing is to add the divisor
630                 // minus one before dividing
631                 let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
632                 let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
633                 for (byte_idx, byte) in self.flags.iter().enumerate() {
634                         let bit_pos_from_left_0_indexed = byte_idx * 8;
635                         let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
636                         let new_bit_pos = bit_pos_from_left_0_indexed % 5;
637                         let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
638                         let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
639                         res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
640                         if new_u5_idx > 0 {
641                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
642                                 res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
643                         }
644                         if new_u5_idx > 1 {
645                                 let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
646                                 res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
647                         }
648                 }
649                 // Trim the highest feature bits.
650                 while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
651                         res_u5s.remove(0);
652                 }
653                 writer.write(&res_u5s)
654         }
655 }
656
657 impl Base32Len for Bolt11InvoiceFeatures {
658         fn base32_len(&self) -> usize {
659                 self.to_base32().len()
660         }
661 }
662
663 impl FromBase32 for Bolt11InvoiceFeatures {
664         type Err = bech32::Error;
665
666         fn from_base32(field_data: &[u5]) -> Result<Bolt11InvoiceFeatures, bech32::Error> {
667                 // Explanation for the "7": the normal way to round up when dividing is to add the divisor
668                 // minus one before dividing
669                 let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
670                 let mut res_bytes: Vec<u8> = vec![0; length_bytes];
671                 for (u5_idx, chunk) in field_data.iter().enumerate() {
672                         let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
673                         let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
674                         let new_bit_pos = bit_pos_from_right_0_indexed % 8;
675                         let chunk_u16 = chunk.to_u8() as u16;
676                         res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
677                         if new_byte_idx != length_bytes - 1 {
678                                 res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
679                         }
680                 }
681                 // Trim the highest feature bits.
682                 while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
683                         res_bytes.pop();
684                 }
685                 Ok(Bolt11InvoiceFeatures::from_le_bytes(res_bytes))
686         }
687 }
688
689 impl<T: sealed::Context> Features<T> {
690         /// Create a blank Features with no features set
691         pub fn empty() -> Self {
692                 Features {
693                         flags: Vec::new(),
694                         mark: PhantomData,
695                 }
696         }
697
698         /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
699         /// included in the result.
700         fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
701                 let from_byte_count = T::KNOWN_FEATURE_MASK.len();
702                 let to_byte_count = C::KNOWN_FEATURE_MASK.len();
703                 let mut flags = Vec::new();
704                 for (i, byte) in self.flags.iter().enumerate() {
705                         if i < from_byte_count && i < to_byte_count {
706                                 let from_known_features = T::KNOWN_FEATURE_MASK[i];
707                                 let to_known_features = C::KNOWN_FEATURE_MASK[i];
708                                 flags.push(byte & from_known_features & to_known_features);
709                         }
710                 }
711                 Features::<C> { flags, mark: PhantomData, }
712         }
713
714         /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
715         /// most on-the-wire encodings.
716         ///
717         /// This is not exported to bindings users as we don't support export across multiple T
718         pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
719                 Features {
720                         flags,
721                         mark: PhantomData,
722                 }
723         }
724
725         #[cfg(test)]
726         /// Gets the underlying flags set, in LE.
727         pub fn le_flags(&self) -> &Vec<u8> {
728                 &self.flags
729         }
730
731         fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
732                 for f in self.flags.iter().rev() { // Swap back to big-endian
733                         f.write(w)?;
734                 }
735                 Ok(())
736         }
737
738         /// Create a [`Features`] given a set of flags, in big-endian. This is in byte order from
739         /// most on-the-wire encodings.
740         ///
741         /// This is not exported to bindings users as we don't support export across multiple T
742         pub fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
743                 flags.reverse(); // Swap to little-endian
744                 Self {
745                         flags,
746                         mark: PhantomData,
747                 }
748         }
749
750         pub(crate) fn supports_any_optional_bits(&self) -> bool {
751                 self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
752         }
753
754         /// Returns true if this `Features` object contains required features unknown by `other`.
755         pub fn requires_unknown_bits_from(&self, other: &Self) -> bool {
756                 // Bitwise AND-ing with all even bits set except for known features will select required
757                 // unknown features.
758                 self.flags.iter().enumerate().any(|(i, &byte)| {
759                         const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
760                         const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
761                         let unknown_features = if i < other.flags.len() {
762                                 // Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
763                                 !(other.flags[i]
764                                         | ((other.flags[i] >> 1) & REQUIRED_FEATURES)
765                                         | ((other.flags[i] << 1) & OPTIONAL_FEATURES))
766                         } else {
767                                 0b11_11_11_11
768                         };
769                         (byte & (REQUIRED_FEATURES & unknown_features)) != 0
770                 })
771         }
772
773         /// Returns true if this `Features` object contains unknown feature flags which are set as
774         /// "required".
775         pub fn requires_unknown_bits(&self) -> bool {
776                 // Bitwise AND-ing with all even bits set except for known features will select required
777                 // unknown features.
778                 let byte_count = T::KNOWN_FEATURE_MASK.len();
779                 self.flags.iter().enumerate().any(|(i, &byte)| {
780                         let required_features = 0b01_01_01_01;
781                         let unknown_features = if i < byte_count {
782                                 !T::KNOWN_FEATURE_MASK[i]
783                         } else {
784                                 0b11_11_11_11
785                         };
786                         (byte & (required_features & unknown_features)) != 0
787                 })
788         }
789
790         pub(crate) fn supports_unknown_bits(&self) -> bool {
791                 // Bitwise AND-ing with all even and odd bits set except for known features will select
792                 // both required and optional unknown features.
793                 let byte_count = T::KNOWN_FEATURE_MASK.len();
794                 self.flags.iter().enumerate().any(|(i, &byte)| {
795                         let unknown_features = if i < byte_count {
796                                 !T::KNOWN_FEATURE_MASK[i]
797                         } else {
798                                 0b11_11_11_11
799                         };
800                         (byte & unknown_features) != 0
801                 })
802         }
803
804         // Returns true if the features within `self` are a subset of the features within `other`.
805         pub(crate) fn is_subset(&self, other: &Self) -> bool {
806                 for (idx, byte) in self.flags.iter().enumerate() {
807                         if let Some(other_byte) = other.flags.get(idx) {
808                                 if byte & other_byte != *byte {
809                                         // `self` has bits set that `other` doesn't.
810                                         return false;
811                                 }
812                         } else {
813                                 if *byte > 0 {
814                                         // `self` has a non-zero byte that `other` doesn't.
815                                         return false;
816                                 }
817                         }
818                 }
819                 true
820         }
821
822         /// Sets a required feature bit. Errors if `bit` is outside the feature range as defined
823         /// by [BOLT 9].
824         ///
825         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
826         /// be set instead (i.e., `bit - 1`).
827         ///
828         /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
829         pub fn set_required_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
830                 self.set_feature_bit(bit - (bit % 2))
831         }
832
833         /// Sets an optional feature bit. Errors if `bit` is outside the feature range as defined
834         /// by [BOLT 9].
835         ///
836         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
837         /// set instead (i.e., `bit + 1`).
838         ///
839         /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
840         pub fn set_optional_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
841                 self.set_feature_bit(bit + (1 - (bit % 2)))
842         }
843
844         fn set_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
845                 if bit > 255 {
846                         return Err(());
847                 }
848                 self.set_bit(bit, false)
849         }
850
851         /// Sets a required custom feature bit. Errors if `bit` is outside the custom range as defined
852         /// by [bLIP 2] or if it is a known `T` feature.
853         ///
854         /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
855         /// be set instead (i.e., `bit - 1`).
856         ///
857         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
858         pub fn set_required_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
859                 self.set_custom_bit(bit - (bit % 2))
860         }
861
862         /// Sets an optional 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.
864         ///
865         /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
866         /// set instead (i.e., `bit + 1`).
867         ///
868         /// [bLIP 2]: https://github.com/lightning/blips/blob/master/blip-0002.md#feature-bits
869         pub fn set_optional_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
870                 self.set_custom_bit(bit + (1 - (bit % 2)))
871         }
872
873         fn set_custom_bit(&mut self, bit: usize) -> Result<(), ()> {
874                 if bit < 256 {
875                         return Err(());
876                 }
877                 self.set_bit(bit, true)
878         }
879
880         fn set_bit(&mut self, bit: usize, custom: bool) -> Result<(), ()> {
881                 let byte_offset = bit / 8;
882                 let mask = 1 << (bit - 8 * byte_offset);
883                 if byte_offset < T::KNOWN_FEATURE_MASK.len() && custom {
884                         if (T::KNOWN_FEATURE_MASK[byte_offset] & mask) != 0 {
885                                 return Err(());
886                         }
887                 }
888
889                 if self.flags.len() <= byte_offset {
890                         self.flags.resize(byte_offset + 1, 0u8);
891                 }
892
893                 self.flags[byte_offset] |= mask;
894
895                 Ok(())
896         }
897 }
898
899 impl<T: sealed::UpfrontShutdownScript> Features<T> {
900         #[cfg(test)]
901         pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
902                 <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
903                 self
904         }
905 }
906
907 impl<T: sealed::ShutdownAnySegwit> Features<T> {
908         #[cfg(test)]
909         pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
910                 <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
911                 self
912         }
913 }
914
915 impl<T: sealed::Wumbo> Features<T> {
916         #[cfg(test)]
917         pub(crate) fn clear_wumbo(mut self) -> Self {
918                 <T as sealed::Wumbo>::clear_bits(&mut self.flags);
919                 self
920         }
921 }
922
923 impl<T: sealed::SCIDPrivacy> Features<T> {
924         pub(crate) fn clear_scid_privacy(&mut self) {
925                 <T as sealed::SCIDPrivacy>::clear_bits(&mut self.flags);
926         }
927 }
928
929 impl<T: sealed::AnchorsZeroFeeHtlcTx> Features<T> {
930         pub(crate) fn clear_anchors_zero_fee_htlc_tx(&mut self) {
931                 <T as sealed::AnchorsZeroFeeHtlcTx>::clear_bits(&mut self.flags);
932         }
933 }
934
935 impl<T: sealed::RouteBlinding> Features<T> {
936         #[cfg(test)]
937         pub(crate) fn clear_route_blinding(&mut self) {
938                 <T as sealed::RouteBlinding>::clear_bits(&mut self.flags);
939         }
940 }
941
942 #[cfg(test)]
943 impl<T: sealed::UnknownFeature> Features<T> {
944         pub(crate) fn unknown() -> Self {
945                 let mut features = Self::empty();
946                 features.set_unknown_feature_required();
947                 features
948         }
949 }
950
951 macro_rules! impl_feature_len_prefixed_write {
952         ($features: ident) => {
953                 impl Writeable for $features {
954                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
955                                 (self.flags.len() as u16).write(w)?;
956                                 self.write_be(w)
957                         }
958                 }
959                 impl Readable for $features {
960                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
961                                 Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
962                         }
963                 }
964         }
965 }
966 impl_feature_len_prefixed_write!(InitFeatures);
967 impl_feature_len_prefixed_write!(ChannelFeatures);
968 impl_feature_len_prefixed_write!(NodeFeatures);
969 impl_feature_len_prefixed_write!(Bolt11InvoiceFeatures);
970 impl_feature_len_prefixed_write!(Bolt12InvoiceFeatures);
971 impl_feature_len_prefixed_write!(BlindedHopFeatures);
972
973 // Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
974 macro_rules! impl_feature_tlv_write {
975         ($features: ident) => {
976                 impl Writeable for $features {
977                         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
978                                 WithoutLength(self).write(w)
979                         }
980                 }
981                 impl Readable for $features {
982                         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
983                                 Ok(WithoutLength::<Self>::read(r)?.0)
984                         }
985                 }
986         }
987 }
988
989 impl_feature_tlv_write!(ChannelTypeFeatures);
990
991 // Some features may appear both in a TLV record and as part of a TLV subtype sequence. The latter
992 // requires a length but the former does not.
993
994 impl<T: sealed::Context> Writeable for WithoutLength<&Features<T>> {
995         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
996                 self.0.write_be(w)
997         }
998 }
999
1000 impl<T: sealed::Context> Readable for WithoutLength<Features<T>> {
1001         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
1002                 let v = io_extras::read_to_end(r)?;
1003                 Ok(WithoutLength(Features::<T>::from_be_bytes(v)))
1004         }
1005 }
1006
1007 #[cfg(test)]
1008 mod tests {
1009         use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, Bolt11InvoiceFeatures, NodeFeatures, OfferFeatures, sealed};
1010         use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
1011         use crate::util::ser::{Readable, WithoutLength, Writeable};
1012
1013         #[test]
1014         fn sanity_test_unknown_bits() {
1015                 let features = ChannelFeatures::empty();
1016                 assert!(!features.requires_unknown_bits());
1017                 assert!(!features.supports_unknown_bits());
1018
1019                 let mut features = ChannelFeatures::empty();
1020                 features.set_unknown_feature_required();
1021                 assert!(features.requires_unknown_bits());
1022                 assert!(features.supports_unknown_bits());
1023
1024                 let mut features = ChannelFeatures::empty();
1025                 features.set_unknown_feature_optional();
1026                 assert!(!features.requires_unknown_bits());
1027                 assert!(features.supports_unknown_bits());
1028         }
1029
1030         #[test]
1031         fn requires_unknown_bits_from() {
1032                 let mut features1 = InitFeatures::empty();
1033                 let mut features2 = InitFeatures::empty();
1034                 assert!(!features1.requires_unknown_bits_from(&features2));
1035                 assert!(!features2.requires_unknown_bits_from(&features1));
1036
1037                 features1.set_data_loss_protect_required();
1038                 assert!(features1.requires_unknown_bits_from(&features2));
1039                 assert!(!features2.requires_unknown_bits_from(&features1));
1040
1041                 features2.set_data_loss_protect_optional();
1042                 assert!(!features1.requires_unknown_bits_from(&features2));
1043                 assert!(!features2.requires_unknown_bits_from(&features1));
1044
1045                 features2.set_gossip_queries_required();
1046                 assert!(!features1.requires_unknown_bits_from(&features2));
1047                 assert!(features2.requires_unknown_bits_from(&features1));
1048
1049                 features1.set_gossip_queries_optional();
1050                 assert!(!features1.requires_unknown_bits_from(&features2));
1051                 assert!(!features2.requires_unknown_bits_from(&features1));
1052
1053                 features1.set_variable_length_onion_required();
1054                 assert!(features1.requires_unknown_bits_from(&features2));
1055                 assert!(!features2.requires_unknown_bits_from(&features1));
1056
1057                 features2.set_variable_length_onion_optional();
1058                 assert!(!features1.requires_unknown_bits_from(&features2));
1059                 assert!(!features2.requires_unknown_bits_from(&features1));
1060
1061                 features1.set_basic_mpp_required();
1062                 features2.set_wumbo_required();
1063                 assert!(features1.requires_unknown_bits_from(&features2));
1064                 assert!(features2.requires_unknown_bits_from(&features1));
1065         }
1066
1067         #[test]
1068         fn convert_to_context_with_relevant_flags() {
1069                 let mut init_features = InitFeatures::empty();
1070                 // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
1071                 // converted as it's only relevant in an init context).
1072                 init_features.set_initial_routing_sync_required();
1073                 init_features.set_data_loss_protect_required();
1074                 init_features.set_variable_length_onion_required();
1075                 init_features.set_static_remote_key_required();
1076                 init_features.set_payment_secret_required();
1077                 init_features.set_basic_mpp_optional();
1078                 init_features.set_wumbo_optional();
1079                 init_features.set_anchors_zero_fee_htlc_tx_optional();
1080                 init_features.set_route_blinding_optional();
1081                 init_features.set_shutdown_any_segwit_optional();
1082                 init_features.set_onion_messages_optional();
1083                 init_features.set_channel_type_optional();
1084                 init_features.set_scid_privacy_optional();
1085                 init_features.set_zero_conf_optional();
1086
1087                 assert!(init_features.initial_routing_sync());
1088                 assert!(!init_features.supports_upfront_shutdown_script());
1089                 assert!(!init_features.supports_gossip_queries());
1090
1091                 let node_features: NodeFeatures = init_features.to_context();
1092                 {
1093                         // Check that the flags are as expected:
1094                         // - option_data_loss_protect (req)
1095                         // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
1096                         // - basic_mpp | wumbo | option_anchors_zero_fee_htlc_tx
1097                         // - option_route_blinding | opt_shutdown_anysegwit
1098                         // - onion_messages
1099                         // - option_channel_type | option_scid_alias
1100                         // - option_zeroconf
1101                         assert_eq!(node_features.flags.len(), 7);
1102                         assert_eq!(node_features.flags[0], 0b00000001);
1103                         assert_eq!(node_features.flags[1], 0b01010001);
1104                         assert_eq!(node_features.flags[2], 0b10001010);
1105                         assert_eq!(node_features.flags[3], 0b00001010);
1106                         assert_eq!(node_features.flags[4], 0b10000000);
1107                         assert_eq!(node_features.flags[5], 0b10100000);
1108                         assert_eq!(node_features.flags[6], 0b00001000);
1109                 }
1110
1111                 // Check that cleared flags are kept blank when converting back:
1112                 // - initial_routing_sync was not applicable to NodeContext
1113                 // - upfront_shutdown_script was cleared before converting
1114                 // - gossip_queries was cleared before converting
1115                 let features: InitFeatures = node_features.to_context_internal();
1116                 assert!(!features.initial_routing_sync());
1117                 assert!(!features.supports_upfront_shutdown_script());
1118                 assert!(!init_features.supports_gossip_queries());
1119         }
1120
1121         #[test]
1122         fn convert_to_context_with_unknown_flags() {
1123                 // Ensure the `from` context has fewer known feature bytes than the `to` context.
1124                 assert!(<sealed::ChannelContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
1125                         <sealed::Bolt11InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
1126                 let mut channel_features = ChannelFeatures::empty();
1127                 channel_features.set_unknown_feature_optional();
1128                 assert!(channel_features.supports_unknown_bits());
1129                 let invoice_features: Bolt11InvoiceFeatures = channel_features.to_context_internal();
1130                 assert!(!invoice_features.supports_unknown_bits());
1131         }
1132
1133         #[test]
1134         fn set_feature_bits() {
1135                 let mut features = Bolt11InvoiceFeatures::empty();
1136                 features.set_basic_mpp_optional();
1137                 features.set_payment_secret_required();
1138                 assert!(features.supports_basic_mpp());
1139                 assert!(!features.requires_basic_mpp());
1140                 assert!(features.requires_payment_secret());
1141                 assert!(features.supports_payment_secret());
1142
1143                 // Set flags manually
1144                 let mut features = NodeFeatures::empty();
1145                 assert!(features.set_optional_feature_bit(55).is_ok());
1146                 assert!(features.supports_keysend());
1147                 assert!(features.set_optional_feature_bit(255).is_ok());
1148                 assert!(features.set_required_feature_bit(256).is_err());
1149         }
1150
1151         #[test]
1152         fn set_custom_bits() {
1153                 let mut features = Bolt11InvoiceFeatures::empty();
1154                 features.set_variable_length_onion_optional();
1155                 assert_eq!(features.flags[1], 0b00000010);
1156
1157                 assert!(features.set_optional_custom_bit(255).is_err());
1158                 assert!(features.set_required_custom_bit(256).is_ok());
1159                 assert!(features.set_required_custom_bit(258).is_ok());
1160                 assert_eq!(features.flags[31], 0b00000000);
1161                 assert_eq!(features.flags[32], 0b00000101);
1162
1163                 let known_bit = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::EVEN_BIT;
1164                 let byte_offset = <sealed::Bolt11InvoiceContext as sealed::PaymentSecret>::BYTE_OFFSET;
1165                 assert_eq!(byte_offset, 1);
1166                 assert_eq!(features.flags[byte_offset], 0b00000010);
1167                 assert!(features.set_required_custom_bit(known_bit).is_err());
1168                 assert_eq!(features.flags[byte_offset], 0b00000010);
1169
1170                 let mut features = Bolt11InvoiceFeatures::empty();
1171                 assert!(features.set_optional_custom_bit(256).is_ok());
1172                 assert!(features.set_optional_custom_bit(259).is_ok());
1173                 assert_eq!(features.flags[32], 0b00001010);
1174
1175                 let mut features = Bolt11InvoiceFeatures::empty();
1176                 assert!(features.set_required_custom_bit(257).is_ok());
1177                 assert!(features.set_required_custom_bit(258).is_ok());
1178                 assert_eq!(features.flags[32], 0b00000101);
1179         }
1180
1181         #[test]
1182         fn encodes_features_without_length() {
1183                 let features = OfferFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1184                 assert_eq!(features.flags.len(), 8);
1185
1186                 let mut serialized_features = Vec::new();
1187                 WithoutLength(&features).write(&mut serialized_features).unwrap();
1188                 assert_eq!(serialized_features.len(), 8);
1189
1190                 let deserialized_features =
1191                         WithoutLength::<OfferFeatures>::read(&mut &serialized_features[..]).unwrap().0;
1192                 assert_eq!(features, deserialized_features);
1193         }
1194
1195         #[test]
1196         fn invoice_features_encoding() {
1197                 let features_as_u5s = vec![
1198                         u5::try_from_u8(6).unwrap(),
1199                         u5::try_from_u8(10).unwrap(),
1200                         u5::try_from_u8(25).unwrap(),
1201                         u5::try_from_u8(1).unwrap(),
1202                         u5::try_from_u8(10).unwrap(),
1203                         u5::try_from_u8(0).unwrap(),
1204                         u5::try_from_u8(20).unwrap(),
1205                         u5::try_from_u8(2).unwrap(),
1206                         u5::try_from_u8(0).unwrap(),
1207                         u5::try_from_u8(6).unwrap(),
1208                         u5::try_from_u8(0).unwrap(),
1209                         u5::try_from_u8(16).unwrap(),
1210                         u5::try_from_u8(1).unwrap(),
1211                 ];
1212                 let features = Bolt11InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
1213
1214                 // Test length calculation.
1215                 assert_eq!(features.base32_len(), 13);
1216
1217                 // Test serialization.
1218                 let features_serialized = features.to_base32();
1219                 assert_eq!(features_as_u5s, features_serialized);
1220
1221                 // Test deserialization.
1222                 let features_deserialized = Bolt11InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
1223                 assert_eq!(features, features_deserialized);
1224         }
1225
1226         #[test]
1227         fn test_channel_type_mapping() {
1228                 // If we map an Bolt11InvoiceFeatures with StaticRemoteKey optional, it should map into a
1229                 // required-StaticRemoteKey ChannelTypeFeatures.
1230                 let mut init_features = InitFeatures::empty();
1231                 init_features.set_static_remote_key_optional();
1232                 let converted_features = ChannelTypeFeatures::from_init(&init_features);
1233                 assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
1234                 assert!(!converted_features.supports_any_optional_bits());
1235                 assert!(converted_features.requires_static_remote_key());
1236         }
1237
1238         #[test]
1239         #[cfg(feature = "std")]
1240         fn test_excess_zero_bytes_ignored() {
1241                 // Checks that `Hash` and `PartialEq` ignore excess zero bytes, which may appear due to
1242                 // feature conversion or because a peer serialized their feature poorly.
1243                 use std::collections::hash_map::DefaultHasher;
1244                 use std::hash::{Hash, Hasher};
1245
1246                 let mut zerod_features = InitFeatures::empty();
1247                 zerod_features.flags = vec![0];
1248                 let empty_features = InitFeatures::empty();
1249                 assert!(empty_features.flags.is_empty());
1250
1251                 assert_eq!(zerod_features, empty_features);
1252
1253                 let mut zerod_hash = DefaultHasher::new();
1254                 zerod_features.hash(&mut zerod_hash);
1255                 let mut empty_hash = DefaultHasher::new();
1256                 empty_features.hash(&mut empty_hash);
1257                 assert_eq!(zerod_hash.finish(), empty_hash.finish());
1258         }
1259 }