-//! Lightning exposes sets of supported operations through "feature flags". This module includes
-//! types to store those feature flags and query for specific flags.
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
-use std::{cmp, fmt};
-use std::result::Result;
-use std::marker::PhantomData;
+//! Feature flag definitions for the Lightning protocol according to [BOLT #9].
+//!
+//! Lightning nodes advertise a supported set of operation through feature flags. Features are
+//! applicable for a specific context as indicated in some [messages]. [`Features`] encapsulates
+//! behavior for specifying and checking feature flags for a particular context. Each feature is
+//! defined internally by a trait specifying the corresponding flags (i.e., even and odd bits).
+//!
+//! Whether a feature is considered "known" or "unknown" is relative to the implementation, whereas
+//! the term "supports" is used in reference to a particular set of [`Features`]. That is, a node
+//! supports a feature if it advertises the feature (as either required or optional) to its peers.
+//! And the implementation can interpret a feature if the feature is known to it.
+//!
+//! The following features are currently required in the LDK:
+//! - `VariableLengthOnion` - requires/supports variable-length routing onion payloads
+//! (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md) for more information).
+//! - `StaticRemoteKey` - requires/supports static key for remote output
+//! (see [BOLT-3](https://github.com/lightning/bolts/blob/master/03-transactions.md) for more information).
+//!
+//! The following features are currently supported in the LDK:
+//! - `DataLossProtect` - requires/supports that a node which has somehow fallen behind, e.g., has been restored from an old backup,
+//! can detect that it has fallen behind
+//! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
+//! - `InitialRoutingSync` - requires/supports that the sending node needs a complete routing information dump
+//! (see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#initial-sync) for more information).
+//! - `UpfrontShutdownScript` - commits to a shutdown scriptpubkey when opening a channel
+//! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-open_channel-message) for more information).
+//! - `GossipQueries` - requires/supports more sophisticated gossip control
+//! (see [BOLT-7](https://github.com/lightning/bolts/blob/master/07-routing-gossip.md) for more information).
+//! - `PaymentSecret` - requires/supports that a node supports payment_secret field
+//! (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md) for more information).
+//! - `BasicMPP` - requires/supports that a node can receive basic multi-part payments
+//! (see [BOLT-4](https://github.com/lightning/bolts/blob/master/04-onion-routing.md#basic-multi-part-payments) for more information).
+//! - `Wumbo` - requires/supports that a node create large channels. Called `option_support_large_channel` in the spec.
+//! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md#the-open_channel-message) for more information).
+//! - `ShutdownAnySegwit` - requires/supports that future segwit versions are allowed in `shutdown`
+//! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
+//! - `OnionMessages` - requires/supports forwarding onion messages
+//! (see [BOLT-7](https://github.com/lightning/bolts/pull/759/files) for more information).
+//! TODO: update link
+//! - `ChannelType` - node supports the channel_type field in open/accept
+//! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
+//! - `SCIDPrivacy` - supply channel aliases for routing
+//! (see [BOLT-2](https://github.com/lightning/bolts/blob/master/02-peer-protocol.md) for more information).
+//! - `Keysend` - send funds to a node without an invoice
+//! (see the [`Keysend` feature assignment proposal](https://github.com/lightning/bolts/issues/605#issuecomment-606679798) for more information).
+//!
+//! [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
+//! [messages]: crate::ln::msgs
-use ln::msgs::DecodeError;
-use util::ser::{Readable, Writeable, Writer};
+use crate::{io, io_extras};
+use crate::prelude::*;
+use core::{cmp, fmt};
+use core::hash::{Hash, Hasher};
+use core::marker::PhantomData;
-mod sealed { // You should just use the type aliases instead.
- pub struct InitContext {}
- pub struct NodeContext {}
- pub struct ChannelContext {}
+use bitcoin::bech32;
+use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5, WriteBase32};
+use crate::ln::msgs::DecodeError;
+use crate::util::ser::{Readable, Writeable, Writer};
- /// An internal trait capturing the various feature context types
- pub trait Context {}
- impl Context for InitContext {}
- impl Context for NodeContext {}
- impl Context for ChannelContext {}
+mod sealed {
+ use crate::prelude::*;
+ use crate::ln::features::Features;
- pub trait DataLossProtect: Context {}
- impl DataLossProtect for InitContext {}
- impl DataLossProtect for NodeContext {}
+ /// The context in which [`Features`] are applicable. Defines which features are known to the
+ /// implementation, though specification of them as required or optional is up to the code
+ /// constructing a features object.
+ pub trait Context {
+ /// Bitmask for selecting features that are known to the implementation.
+ const KNOWN_FEATURE_MASK: &'static [u8];
+ }
+
+ /// Defines a [`Context`] by stating which features it requires and which are optional. Features
+ /// are specified as a comma-separated list of bytes where each byte is a pipe-delimited list of
+ /// feature identifiers.
+ macro_rules! define_context {
+ ($context: ident, [$( $( $known_feature: ident )|*, )*]) => {
+ #[derive(Eq, PartialEq)]
+ pub struct $context {}
+
+ impl Context for $context {
+ const KNOWN_FEATURE_MASK: &'static [u8] = &[
+ $(
+ 0b00_00_00_00 $(|
+ <Self as $known_feature>::REQUIRED_MASK |
+ <Self as $known_feature>::OPTIONAL_MASK)*,
+ )*
+ ];
+ }
+
+ impl alloc::fmt::Display for Features<$context> {
+ fn fmt(&self, fmt: &mut alloc::fmt::Formatter) -> Result<(), alloc::fmt::Error> {
+ $(
+ $(
+ fmt.write_fmt(format_args!("{}: {}, ", stringify!($known_feature),
+ if <$context as $known_feature>::requires_feature(&self.flags) { "required" }
+ else if <$context as $known_feature>::supports_feature(&self.flags) { "supported" }
+ else { "not supported" }))?;
+ )*
+ {} // Rust gets mad if we only have a $()* block here, so add a dummy {}
+ )*
+ fmt.write_fmt(format_args!("unknown flags: {}",
+ if self.requires_unknown_bits() { "required" }
+ else if self.supports_unknown_bits() { "supported" } else { "none" }))
+ }
+ }
+ };
+ }
+
+ define_context!(InitContext, [
+ // Byte 0
+ DataLossProtect | InitialRoutingSync | UpfrontShutdownScript | GossipQueries,
+ // Byte 1
+ VariableLengthOnion | StaticRemoteKey | PaymentSecret,
+ // Byte 2
+ BasicMPP | Wumbo,
+ // Byte 3
+ ShutdownAnySegwit,
+ // Byte 4
+ OnionMessages,
+ // Byte 5
+ ChannelType | SCIDPrivacy,
+ // Byte 6
+ ZeroConf,
+ ]);
+ define_context!(NodeContext, [
+ // Byte 0
+ DataLossProtect | UpfrontShutdownScript | GossipQueries,
+ // Byte 1
+ VariableLengthOnion | StaticRemoteKey | PaymentSecret,
+ // Byte 2
+ BasicMPP | Wumbo,
+ // Byte 3
+ ShutdownAnySegwit,
+ // Byte 4
+ OnionMessages,
+ // Byte 5
+ ChannelType | SCIDPrivacy,
+ // Byte 6
+ ZeroConf | Keysend,
+ ]);
+ define_context!(ChannelContext, []);
+ define_context!(InvoiceContext, [
+ // Byte 0
+ ,
+ // Byte 1
+ VariableLengthOnion | PaymentSecret,
+ // Byte 2
+ BasicMPP,
+ ]);
+ define_context!(OfferContext, []);
+ define_context!(InvoiceRequestContext, []);
+ // This isn't a "real" feature context, and is only used in the channel_type field in an
+ // `OpenChannel` message.
+ define_context!(ChannelTypeContext, [
+ // Byte 0
+ ,
+ // Byte 1
+ StaticRemoteKey,
+ // Byte 2
+ ,
+ // Byte 3
+ ,
+ // Byte 4
+ ,
+ // Byte 5
+ SCIDPrivacy,
+ // Byte 6
+ ZeroConf,
+ ]);
+
+ /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
+ /// useful for manipulating feature flags.
+ macro_rules! define_feature {
+ ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
+ $required_setter: ident, $supported_getter: ident) => {
+ #[doc = $doc]
+ ///
+ /// See [BOLT #9] for details.
+ ///
+ /// [BOLT #9]: https://github.com/lightning/bolts/blob/master/09-features.md
+ pub trait $feature: Context {
+ /// The bit used to signify that the feature is required.
+ const EVEN_BIT: usize = $odd_bit - 1;
+
+ /// The bit used to signify that the feature is optional.
+ const ODD_BIT: usize = $odd_bit;
+
+ /// Assertion that [`EVEN_BIT`] is actually even.
+ ///
+ /// [`EVEN_BIT`]: #associatedconstant.EVEN_BIT
+ const ASSERT_EVEN_BIT_PARITY: usize;
+
+ /// Assertion that [`ODD_BIT`] is actually odd.
+ ///
+ /// [`ODD_BIT`]: #associatedconstant.ODD_BIT
+ const ASSERT_ODD_BIT_PARITY: usize;
+
+ /// Assertion that the bits are set in the context's [`KNOWN_FEATURE_MASK`].
+ ///
+ /// [`KNOWN_FEATURE_MASK`]: Context::KNOWN_FEATURE_MASK
+ #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
+ const ASSERT_BITS_IN_MASK: u8;
+
+ /// The byte where the feature is set.
+ const BYTE_OFFSET: usize = Self::EVEN_BIT / 8;
+
+ /// The bitmask for the feature's required flag relative to the [`BYTE_OFFSET`].
+ ///
+ /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
+ const REQUIRED_MASK: u8 = 1 << (Self::EVEN_BIT - 8 * Self::BYTE_OFFSET);
+
+ /// The bitmask for the feature's optional flag relative to the [`BYTE_OFFSET`].
+ ///
+ /// [`BYTE_OFFSET`]: #associatedconstant.BYTE_OFFSET
+ const OPTIONAL_MASK: u8 = 1 << (Self::ODD_BIT - 8 * Self::BYTE_OFFSET);
+
+ /// Returns whether the feature is required by the given flags.
+ #[inline]
+ fn requires_feature(flags: &Vec<u8>) -> bool {
+ flags.len() > Self::BYTE_OFFSET &&
+ (flags[Self::BYTE_OFFSET] & Self::REQUIRED_MASK) != 0
+ }
+
+ /// Returns whether the feature is supported by the given flags.
+ #[inline]
+ fn supports_feature(flags: &Vec<u8>) -> bool {
+ flags.len() > Self::BYTE_OFFSET &&
+ (flags[Self::BYTE_OFFSET] & (Self::REQUIRED_MASK | Self::OPTIONAL_MASK)) != 0
+ }
+
+ /// Sets the feature's required (even) bit in the given flags.
+ #[inline]
+ fn set_required_bit(flags: &mut Vec<u8>) {
+ if flags.len() <= Self::BYTE_OFFSET {
+ flags.resize(Self::BYTE_OFFSET + 1, 0u8);
+ }
- pub trait InitialRoutingSync: Context {}
- impl InitialRoutingSync for InitContext {}
+ flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
+ }
- pub trait UpfrontShutdownScript: Context {}
- impl UpfrontShutdownScript for InitContext {}
- impl UpfrontShutdownScript for NodeContext {}
+ /// Sets the feature's optional (odd) bit in the given flags.
+ #[inline]
+ fn set_optional_bit(flags: &mut Vec<u8>) {
+ if flags.len() <= Self::BYTE_OFFSET {
+ flags.resize(Self::BYTE_OFFSET + 1, 0u8);
+ }
+
+ flags[Self::BYTE_OFFSET] |= Self::OPTIONAL_MASK;
+ }
+
+ /// Clears the feature's required (even) and optional (odd) bits from the given
+ /// flags.
+ #[inline]
+ fn clear_bits(flags: &mut Vec<u8>) {
+ if flags.len() > Self::BYTE_OFFSET {
+ flags[Self::BYTE_OFFSET] &= !Self::REQUIRED_MASK;
+ flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
+ }
+
+ let last_non_zero_byte = flags.iter().rposition(|&byte| byte != 0);
+ let size = if let Some(offset) = last_non_zero_byte { offset + 1 } else { 0 };
+ flags.resize(size, 0u8);
+ }
+ }
+
+ impl <T: $feature> Features<T> {
+ /// Set this feature as optional.
+ pub fn $optional_setter(&mut self) {
+ <T as $feature>::set_optional_bit(&mut self.flags);
+ }
+
+ /// Set this feature as required.
+ pub fn $required_setter(&mut self) {
+ <T as $feature>::set_required_bit(&mut self.flags);
+ }
+
+ /// Checks if this feature is supported.
+ pub fn $supported_getter(&self) -> bool {
+ <T as $feature>::supports_feature(&self.flags)
+ }
+ }
+
+ $(
+ impl $feature for $context {
+ // EVEN_BIT % 2 == 0
+ const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
+
+ // ODD_BIT % 2 == 1
+ const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
+
+ // (byte & (REQUIRED_MASK | OPTIONAL_MASK)) >> (EVEN_BIT % 8) == 3
+ #[cfg(not(test))] // We violate this constraint with `UnknownFeature`
+ const ASSERT_BITS_IN_MASK: u8 =
+ ((<$context>::KNOWN_FEATURE_MASK[<Self as $feature>::BYTE_OFFSET] & (<Self as $feature>::REQUIRED_MASK | <Self as $feature>::OPTIONAL_MASK))
+ >> (<Self as $feature>::EVEN_BIT % 8)) - 3;
+ }
+ )*
+ };
+ ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr, $optional_setter: ident,
+ $required_setter: ident, $supported_getter: ident, $required_getter: ident) => {
+ define_feature!($odd_bit, $feature, [$($context),+], $doc, $optional_setter, $required_setter, $supported_getter);
+ impl <T: $feature> Features<T> {
+ /// Checks if this feature is required.
+ pub fn $required_getter(&self) -> bool {
+ <T as $feature>::requires_feature(&self.flags)
+ }
+ }
+ }
+ }
+
+ define_feature!(1, DataLossProtect, [InitContext, NodeContext],
+ "Feature flags for `option_data_loss_protect`.", set_data_loss_protect_optional,
+ set_data_loss_protect_required, supports_data_loss_protect, requires_data_loss_protect);
+ // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
+ define_feature!(3, InitialRoutingSync, [InitContext], "Feature flags for `initial_routing_sync`.",
+ set_initial_routing_sync_optional, set_initial_routing_sync_required,
+ initial_routing_sync);
+ define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
+ "Feature flags for `option_upfront_shutdown_script`.", set_upfront_shutdown_script_optional,
+ set_upfront_shutdown_script_required, supports_upfront_shutdown_script,
+ requires_upfront_shutdown_script);
+ define_feature!(7, GossipQueries, [InitContext, NodeContext],
+ "Feature flags for `gossip_queries`.", set_gossip_queries_optional, set_gossip_queries_required,
+ supports_gossip_queries, requires_gossip_queries);
+ define_feature!(9, VariableLengthOnion, [InitContext, NodeContext, InvoiceContext],
+ "Feature flags for `var_onion_optin`.", set_variable_length_onion_optional,
+ set_variable_length_onion_required, supports_variable_length_onion,
+ requires_variable_length_onion);
+ define_feature!(13, StaticRemoteKey, [InitContext, NodeContext, ChannelTypeContext],
+ "Feature flags for `option_static_remotekey`.", set_static_remote_key_optional,
+ set_static_remote_key_required, supports_static_remote_key, requires_static_remote_key);
+ define_feature!(15, PaymentSecret, [InitContext, NodeContext, InvoiceContext],
+ "Feature flags for `payment_secret`.", set_payment_secret_optional, set_payment_secret_required,
+ supports_payment_secret, requires_payment_secret);
+ define_feature!(17, BasicMPP, [InitContext, NodeContext, InvoiceContext],
+ "Feature flags for `basic_mpp`.", set_basic_mpp_optional, set_basic_mpp_required,
+ supports_basic_mpp, requires_basic_mpp);
+ define_feature!(19, Wumbo, [InitContext, NodeContext],
+ "Feature flags for `option_support_large_channel` (aka wumbo channels).", set_wumbo_optional, set_wumbo_required,
+ supports_wumbo, requires_wumbo);
+ define_feature!(27, ShutdownAnySegwit, [InitContext, NodeContext],
+ "Feature flags for `opt_shutdown_anysegwit`.", set_shutdown_any_segwit_optional,
+ set_shutdown_any_segwit_required, supports_shutdown_anysegwit, requires_shutdown_anysegwit);
+ define_feature!(39, OnionMessages, [InitContext, NodeContext],
+ "Feature flags for `option_onion_messages`.", set_onion_messages_optional,
+ set_onion_messages_required, supports_onion_messages, requires_onion_messages);
+ define_feature!(45, ChannelType, [InitContext, NodeContext],
+ "Feature flags for `option_channel_type`.", set_channel_type_optional,
+ set_channel_type_required, supports_channel_type, requires_channel_type);
+ define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
+ "Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
+ set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
+ define_feature!(51, ZeroConf, [InitContext, NodeContext, ChannelTypeContext],
+ "Feature flags for accepting channels with zero confirmations. Called `option_zeroconf` in the BOLTs",
+ set_zero_conf_optional, set_zero_conf_required, supports_zero_conf, requires_zero_conf);
+ define_feature!(55, Keysend, [NodeContext],
+ "Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
+ supports_keysend, requires_keysend);
+
+ #[cfg(test)]
+ define_feature!(123456789, UnknownFeature,
+ [NodeContext, ChannelContext, InvoiceContext, OfferContext, InvoiceRequestContext],
+ "Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
+ set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
}
/// Tracks the set of features which a node implements, templated by the context in which it
/// appears.
+///
+/// (C-not exported) as we map the concrete feature types below directly instead
+#[derive(Eq)]
pub struct Features<T: sealed::Context> {
- /// Note that, for convinience, flags is LITTLE endian (despite being big-endian on the wire)
+ /// Note that, for convenience, flags is LITTLE endian (despite being big-endian on the wire)
flags: Vec<u8>,
mark: PhantomData<T>,
}
+impl <T: sealed::Context> Features<T> {
+ pub(crate) fn or(mut self, o: Self) -> Self {
+ let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
+ self.flags.resize(total_feature_len, 0u8);
+ for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
+ *byte |= *o_byte;
+ }
+ self
+ }
+}
+
impl<T: sealed::Context> Clone for Features<T> {
fn clone(&self) -> Self {
Self {
}
}
}
+impl<T: sealed::Context> Hash for Features<T> {
+ fn hash<H: Hasher>(&self, hasher: &mut H) {
+ self.flags.hash(hasher);
+ }
+}
impl<T: sealed::Context> PartialEq for Features<T> {
fn eq(&self, o: &Self) -> bool {
self.flags.eq(&o.flags)
}
}
-/// A feature message as it appears in an init message
+/// Features used within an `init` message.
pub type InitFeatures = Features<sealed::InitContext>;
-/// A feature message as it appears in a node_announcement message
+/// Features used within a `node_announcement` message.
pub type NodeFeatures = Features<sealed::NodeContext>;
-/// A feature message as it appears in a channel_announcement message
+/// Features used within a `channel_announcement` message.
pub type ChannelFeatures = Features<sealed::ChannelContext>;
+/// Features used within an invoice.
+pub type InvoiceFeatures = Features<sealed::InvoiceContext>;
+/// Features used within an `offer`.
+pub type OfferFeatures = Features<sealed::OfferContext>;
+/// Features used within an `invoice_request`.
+pub type InvoiceRequestFeatures = Features<sealed::InvoiceRequestContext>;
-impl InitFeatures {
- /// Create a Features with the features we support
- pub fn supported() -> InitFeatures {
- InitFeatures {
- flags: vec![2 | 1 << 5],
- mark: PhantomData,
- }
- }
+/// Features used within the channel_type field in an OpenChannel message.
+///
+/// A channel is always of some known "type", describing the transaction formats used and the exact
+/// semantics of our interaction with our peer.
+///
+/// Note that because a channel is a specific type which is proposed by the opener and accepted by
+/// the counterparty, only required features are allowed here.
+///
+/// This is serialized differently from other feature types - it is not prefixed by a length, and
+/// thus must only appear inside a TLV where its length is known in advance.
+pub type ChannelTypeFeatures = Features<sealed::ChannelTypeContext>;
+impl InitFeatures {
/// Writes all features present up to, and including, 13.
- pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
+ pub(crate) fn write_up_to_13<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
let len = cmp::min(2, self.flags.len());
- w.size_hint(len + 2);
(len as u16).write(w)?;
for i in (0..len).rev() {
if i == 0 {
Ok(())
}
- /// or's another InitFeatures into this one.
- pub(crate) fn or(mut self, o: InitFeatures) -> InitFeatures {
- let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
- self.flags.resize(total_feature_len, 0u8);
- for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
- *byte |= *o_byte;
- }
- self
+ /// Converts `InitFeatures` to `Features<C>`. Only known `InitFeatures` relevant to context `C`
+ /// are included in the result.
+ pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
+ self.to_context_internal()
}
}
-impl ChannelFeatures {
- /// Create a Features with the features we support
- #[cfg(not(feature = "fuzztarget"))]
- pub(crate) fn supported() -> ChannelFeatures {
- ChannelFeatures {
- flags: Vec::new(),
- mark: PhantomData,
- }
+impl InvoiceFeatures {
+ /// Converts `InvoiceFeatures` to `Features<C>`. Only known `InvoiceFeatures` relevant to
+ /// context `C` are included in the result.
+ pub(crate) fn to_context<C: sealed::Context>(&self) -> Features<C> {
+ self.to_context_internal()
}
- #[cfg(feature = "fuzztarget")]
- pub fn supported() -> ChannelFeatures {
- ChannelFeatures {
- flags: Vec::new(),
- mark: PhantomData,
+
+ /// Getting a route for a keysend payment to a private node requires providing the payee's
+ /// features (since they were not announced in a node announcement). However, keysend payments
+ /// don't have an invoice to pull the payee's features from, so this method is provided for use in
+ /// [`PaymentParameters::for_keysend`], thus omitting the need for payers to manually construct an
+ /// `InvoiceFeatures` for [`find_route`].
+ ///
+ /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
+ /// [`find_route`]: crate::routing::router::find_route
+ pub(crate) fn for_keysend() -> InvoiceFeatures {
+ let mut res = InvoiceFeatures::empty();
+ res.set_variable_length_onion_optional();
+ res
+ }
+}
+
+impl ChannelTypeFeatures {
+ /// Constructs the implicit channel type based on the common supported types between us and our
+ /// counterparty
+ pub(crate) fn from_counterparty_init(counterparty_init: &InitFeatures) -> Self {
+ let mut ret = counterparty_init.to_context_internal();
+ // ChannelTypeFeatures must only contain required bits, so we OR the required forms of all
+ // optional bits and then AND out the optional ones.
+ for byte in ret.flags.iter_mut() {
+ *byte |= (*byte & 0b10_10_10_10) >> 1;
+ *byte &= 0b01_01_01_01;
}
+ ret
}
- /// Takes the flags that we know how to interpret in an init-context features that are also
- /// relevant in a channel-context features and creates a channel-context features from them.
- pub(crate) fn with_known_relevant_init_flags(_init_ctx: &InitFeatures) -> Self {
- // There are currently no channel flags defined that we understand.
- Self { flags: Vec::new(), mark: PhantomData, }
+ /// Constructs a ChannelTypeFeatures with only static_remotekey set
+ pub(crate) fn only_static_remote_key() -> Self {
+ let mut ret = Self::empty();
+ <sealed::ChannelTypeContext as sealed::StaticRemoteKey>::set_required_bit(&mut ret.flags);
+ ret
}
}
-impl NodeFeatures {
- /// Create a Features with the features we support
- #[cfg(not(feature = "fuzztarget"))]
- pub(crate) fn supported() -> NodeFeatures {
- NodeFeatures {
- flags: vec![2 | 1 << 5],
- mark: PhantomData,
+impl ToBase32 for InvoiceFeatures {
+ fn write_base32<W: WriteBase32>(&self, writer: &mut W) -> Result<(), <W as WriteBase32>::Err> {
+ // Explanation for the "4": the normal way to round up when dividing is to add the divisor
+ // minus one before dividing
+ let length_u5s = (self.flags.len() * 8 + 4) / 5 as usize;
+ let mut res_u5s: Vec<u5> = vec![u5::try_from_u8(0).unwrap(); length_u5s];
+ for (byte_idx, byte) in self.flags.iter().enumerate() {
+ let bit_pos_from_left_0_indexed = byte_idx * 8;
+ let new_u5_idx = length_u5s - (bit_pos_from_left_0_indexed / 5) as usize - 1;
+ let new_bit_pos = bit_pos_from_left_0_indexed % 5;
+ let shifted_chunk_u16 = (*byte as u16) << new_bit_pos;
+ let curr_u5_as_u8 = res_u5s[new_u5_idx].to_u8();
+ res_u5s[new_u5_idx] = u5::try_from_u8(curr_u5_as_u8 | ((shifted_chunk_u16 & 0x001f) as u8)).unwrap();
+ if new_u5_idx > 0 {
+ let curr_u5_as_u8 = res_u5s[new_u5_idx - 1].to_u8();
+ res_u5s[new_u5_idx - 1] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 5) & 0x001f) as u8)).unwrap();
+ }
+ if new_u5_idx > 1 {
+ let curr_u5_as_u8 = res_u5s[new_u5_idx - 2].to_u8();
+ res_u5s[new_u5_idx - 2] = u5::try_from_u8(curr_u5_as_u8 | (((shifted_chunk_u16 >> 10) & 0x001f) as u8)).unwrap();
+ }
}
- }
- #[cfg(feature = "fuzztarget")]
- pub fn supported() -> NodeFeatures {
- NodeFeatures {
- flags: vec![2 | 1 << 5],
- mark: PhantomData,
+ // Trim the highest feature bits.
+ while !res_u5s.is_empty() && res_u5s[0] == u5::try_from_u8(0).unwrap() {
+ res_u5s.remove(0);
}
+ writer.write(&res_u5s)
}
+}
- /// Takes the flags that we know how to interpret in an init-context features that are also
- /// relevant in a node-context features and creates a node-context features from them.
- pub(crate) fn with_known_relevant_init_flags(init_ctx: &InitFeatures) -> Self {
- let mut flags = Vec::new();
- if init_ctx.flags.len() > 0 {
- // Pull out data_loss_protect and upfront_shutdown_script (bits 0, 1, 4, and 5)
- flags.push(init_ctx.flags.last().unwrap() & 0b00110011);
+impl Base32Len for InvoiceFeatures {
+ fn base32_len(&self) -> usize {
+ self.to_base32().len()
+ }
+}
+
+impl FromBase32 for InvoiceFeatures {
+ type Err = bech32::Error;
+
+ fn from_base32(field_data: &[u5]) -> Result<InvoiceFeatures, bech32::Error> {
+ // Explanation for the "7": the normal way to round up when dividing is to add the divisor
+ // minus one before dividing
+ let length_bytes = (field_data.len() * 5 + 7) / 8 as usize;
+ let mut res_bytes: Vec<u8> = vec![0; length_bytes];
+ for (u5_idx, chunk) in field_data.iter().enumerate() {
+ let bit_pos_from_right_0_indexed = (field_data.len() - u5_idx - 1) * 5;
+ let new_byte_idx = (bit_pos_from_right_0_indexed / 8) as usize;
+ let new_bit_pos = bit_pos_from_right_0_indexed % 8;
+ let chunk_u16 = chunk.to_u8() as u16;
+ res_bytes[new_byte_idx] |= ((chunk_u16 << new_bit_pos) & 0xff) as u8;
+ if new_byte_idx != length_bytes - 1 {
+ res_bytes[new_byte_idx + 1] |= ((chunk_u16 >> (8-new_bit_pos)) & 0xff) as u8;
+ }
+ }
+ // Trim the highest feature bits.
+ while !res_bytes.is_empty() && res_bytes[res_bytes.len() - 1] == 0 {
+ res_bytes.pop();
}
- Self { flags, mark: PhantomData, }
+ Ok(InvoiceFeatures::from_le_bytes(res_bytes))
}
}
impl<T: sealed::Context> Features<T> {
/// Create a blank Features with no features set
- pub fn empty() -> Features<T> {
+ pub fn empty() -> Self {
Features {
flags: Vec::new(),
mark: PhantomData,
}
}
- #[cfg(test)]
- /// Create a Features given a set of flags, in LE.
+ /// Converts `Features<T>` to `Features<C>`. Only known `T` features relevant to context `C` are
+ /// included in the result.
+ fn to_context_internal<C: sealed::Context>(&self) -> Features<C> {
+ let from_byte_count = T::KNOWN_FEATURE_MASK.len();
+ let to_byte_count = C::KNOWN_FEATURE_MASK.len();
+ let mut flags = Vec::new();
+ for (i, byte) in self.flags.iter().enumerate() {
+ if i < from_byte_count && i < to_byte_count {
+ let from_known_features = T::KNOWN_FEATURE_MASK[i];
+ let to_known_features = C::KNOWN_FEATURE_MASK[i];
+ flags.push(byte & from_known_features & to_known_features);
+ }
+ }
+ Features::<C> { flags, mark: PhantomData, }
+ }
+
+ /// Create a Features given a set of flags, in little-endian. This is in reverse byte order from
+ /// most on-the-wire encodings.
+ /// (C-not exported) as we don't support export across multiple T
pub fn from_le_bytes(flags: Vec<u8>) -> Features<T> {
Features {
flags,
&self.flags
}
- pub(crate) fn requires_unknown_bits(&self) -> bool {
- self.flags.iter().enumerate().any(|(idx, &byte)| {
- ( idx != 0 && (byte & 0x55) != 0 ) || ( idx == 0 && (byte & 0x14) != 0 )
+ fn write_be<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ for f in self.flags.iter().rev() { // Swap back to big-endian
+ f.write(w)?;
+ }
+ Ok(())
+ }
+
+ fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
+ flags.reverse(); // Swap to little-endian
+ Self {
+ flags,
+ mark: PhantomData,
+ }
+ }
+
+ pub(crate) fn supports_any_optional_bits(&self) -> bool {
+ self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
+ }
+
+ /// Returns true if this `Features` object contains unknown feature flags which are set as
+ /// "required".
+ pub fn requires_unknown_bits(&self) -> bool {
+ // Bitwise AND-ing with all even bits set except for known features will select required
+ // unknown features.
+ let byte_count = T::KNOWN_FEATURE_MASK.len();
+ self.flags.iter().enumerate().any(|(i, &byte)| {
+ let required_features = 0b01_01_01_01;
+ let unknown_features = if i < byte_count {
+ !T::KNOWN_FEATURE_MASK[i]
+ } else {
+ 0b11_11_11_11
+ };
+ (byte & (required_features & unknown_features)) != 0
})
}
pub(crate) fn supports_unknown_bits(&self) -> bool {
- self.flags.iter().enumerate().any(|(idx, &byte)| {
- ( idx != 0 && byte != 0 ) || ( idx == 0 && (byte & 0xc4) != 0 )
+ // Bitwise AND-ing with all even and odd bits set except for known features will select
+ // both required and optional unknown features.
+ let byte_count = T::KNOWN_FEATURE_MASK.len();
+ self.flags.iter().enumerate().any(|(i, &byte)| {
+ let unknown_features = if i < byte_count {
+ !T::KNOWN_FEATURE_MASK[i]
+ } else {
+ 0b11_11_11_11
+ };
+ (byte & unknown_features) != 0
})
}
+}
- /// The number of bytes required to represent the feature flags present. This does not include
- /// the length bytes which are included in the serialized form.
- pub(crate) fn byte_count(&self) -> usize {
- self.flags.len()
+impl<T: sealed::UpfrontShutdownScript> Features<T> {
+ #[cfg(test)]
+ pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
+ <T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
+ self
}
+}
+impl<T: sealed::ShutdownAnySegwit> Features<T> {
#[cfg(test)]
- pub(crate) fn set_require_unknown_bits(&mut self) {
- let newlen = cmp::max(2, self.flags.len());
- self.flags.resize(newlen, 0u8);
- self.flags[1] |= 0x40;
+ pub(crate) fn clear_shutdown_anysegwit(mut self) -> Self {
+ <T as sealed::ShutdownAnySegwit>::clear_bits(&mut self.flags);
+ self
}
+}
+impl<T: sealed::Wumbo> Features<T> {
#[cfg(test)]
- pub(crate) fn clear_require_unknown_bits(&mut self) {
- let newlen = cmp::max(2, self.flags.len());
- self.flags.resize(newlen, 0u8);
- self.flags[1] &= !0x40;
- if self.flags.len() == 2 && self.flags[1] == 0 {
- self.flags.resize(1, 0u8);
- }
+ pub(crate) fn clear_wumbo(mut self) -> Self {
+ <T as sealed::Wumbo>::clear_bits(&mut self.flags);
+ self
}
}
-impl<T: sealed::DataLossProtect> Features<T> {
- pub(crate) fn supports_data_loss_protect(&self) -> bool {
- self.flags.len() > 0 && (self.flags[0] & 3) != 0
+#[cfg(test)]
+impl<T: sealed::UnknownFeature> Features<T> {
+ pub(crate) fn unknown() -> Self {
+ let mut features = Self::empty();
+ features.set_unknown_feature_required();
+ features
}
}
-impl<T: sealed::UpfrontShutdownScript> Features<T> {
- pub(crate) fn supports_upfront_shutdown_script(&self) -> bool {
- self.flags.len() > 0 && (self.flags[0] & (3 << 4)) != 0
- }
- #[cfg(test)]
- pub(crate) fn unset_upfront_shutdown_script(&mut self) {
- self.flags[0] ^= 1 << 5;
+macro_rules! impl_feature_len_prefixed_write {
+ ($features: ident) => {
+ impl Writeable for $features {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ (self.flags.len() as u16).write(w)?;
+ self.write_be(w)
+ }
+ }
+ impl Readable for $features {
+ fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
+ Ok(Self::from_be_bytes(Vec::<u8>::read(r)?))
+ }
+ }
}
}
+impl_feature_len_prefixed_write!(InitFeatures);
+impl_feature_len_prefixed_write!(ChannelFeatures);
+impl_feature_len_prefixed_write!(NodeFeatures);
+impl_feature_len_prefixed_write!(InvoiceFeatures);
-impl<T: sealed::InitialRoutingSync> Features<T> {
- pub(crate) fn initial_routing_sync(&self) -> bool {
- self.flags.len() > 0 && (self.flags[0] & (1 << 3)) != 0
- }
- pub(crate) fn set_initial_routing_sync(&mut self) {
- if self.flags.len() == 0 {
- self.flags.resize(1, 1 << 3);
- } else {
- self.flags[0] |= 1 << 3;
+// Some features only appear inside of TLVs, so they don't have a length prefix when serialized.
+macro_rules! impl_feature_tlv_write {
+ ($features: ident) => {
+ impl Writeable for $features {
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ self.write_be(w)
+ }
+ }
+ impl Readable for $features {
+ fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
+ let v = io_extras::read_to_end(r)?;
+ Ok(Self::from_be_bytes(v))
+ }
}
}
}
-impl<T: sealed::Context> Writeable for Features<T> {
- fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
- w.size_hint(self.flags.len() + 2);
- (self.flags.len() as u16).write(w)?;
- for f in self.flags.iter().rev() { // Swap back to big-endian
- f.write(w)?;
+impl_feature_tlv_write!(ChannelTypeFeatures);
+impl_feature_tlv_write!(OfferFeatures);
+impl_feature_tlv_write!(InvoiceRequestFeatures);
+
+#[cfg(test)]
+mod tests {
+ use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures, sealed};
+ use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
+
+ #[test]
+ fn sanity_test_unknown_bits() {
+ let features = ChannelFeatures::empty();
+ assert!(!features.requires_unknown_bits());
+ assert!(!features.supports_unknown_bits());
+
+ let mut features = ChannelFeatures::empty();
+ features.set_unknown_feature_required();
+ assert!(features.requires_unknown_bits());
+ assert!(features.supports_unknown_bits());
+
+ let mut features = ChannelFeatures::empty();
+ features.set_unknown_feature_optional();
+ assert!(!features.requires_unknown_bits());
+ assert!(features.supports_unknown_bits());
+ }
+
+ #[test]
+ fn convert_to_context_with_relevant_flags() {
+ let mut init_features = InitFeatures::empty();
+ // Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
+ // converted as it's only relevant in an init context).
+ init_features.set_initial_routing_sync_required();
+ init_features.set_data_loss_protect_optional();
+ init_features.set_variable_length_onion_required();
+ init_features.set_static_remote_key_required();
+ init_features.set_payment_secret_required();
+ init_features.set_basic_mpp_optional();
+ init_features.set_wumbo_optional();
+ init_features.set_shutdown_any_segwit_optional();
+ init_features.set_onion_messages_optional();
+ init_features.set_channel_type_optional();
+ init_features.set_scid_privacy_optional();
+ init_features.set_zero_conf_optional();
+
+ assert!(init_features.initial_routing_sync());
+ assert!(!init_features.supports_upfront_shutdown_script());
+ assert!(!init_features.supports_gossip_queries());
+
+ let node_features: NodeFeatures = init_features.to_context();
+ {
+ // Check that the flags are as expected:
+ // - option_data_loss_protect
+ // - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
+ // - basic_mpp | wumbo
+ // - opt_shutdown_anysegwit
+ // - onion_messages
+ // - option_channel_type | option_scid_alias
+ // - option_zeroconf
+ assert_eq!(node_features.flags.len(), 7);
+ assert_eq!(node_features.flags[0], 0b00000010);
+ assert_eq!(node_features.flags[1], 0b01010001);
+ assert_eq!(node_features.flags[2], 0b00001010);
+ assert_eq!(node_features.flags[3], 0b00001000);
+ assert_eq!(node_features.flags[4], 0b10000000);
+ assert_eq!(node_features.flags[5], 0b10100000);
+ assert_eq!(node_features.flags[6], 0b00001000);
}
- Ok(())
+
+ // Check that cleared flags are kept blank when converting back:
+ // - initial_routing_sync was not applicable to NodeContext
+ // - upfront_shutdown_script was cleared before converting
+ // - gossip_queries was cleared before converting
+ let features: InitFeatures = node_features.to_context_internal();
+ assert!(!features.initial_routing_sync());
+ assert!(!features.supports_upfront_shutdown_script());
+ assert!(!init_features.supports_gossip_queries());
}
-}
-impl<R: ::std::io::Read, T: sealed::Context> Readable<R> for Features<T> {
- fn read(r: &mut R) -> Result<Self, DecodeError> {
- let mut flags: Vec<u8> = Readable::read(r)?;
- flags.reverse(); // Swap to little-endian
- Ok(Self {
- flags,
- mark: PhantomData,
- })
+ #[test]
+ fn convert_to_context_with_unknown_flags() {
+ // Ensure the `from` context has fewer known feature bytes than the `to` context.
+ assert!(<sealed::InvoiceContext as sealed::Context>::KNOWN_FEATURE_MASK.len() <
+ <sealed::NodeContext as sealed::Context>::KNOWN_FEATURE_MASK.len());
+ let mut invoice_features = InvoiceFeatures::empty();
+ invoice_features.set_unknown_feature_optional();
+ assert!(invoice_features.supports_unknown_bits());
+ let node_features: NodeFeatures = invoice_features.to_context();
+ assert!(!node_features.supports_unknown_bits());
+ }
+
+ #[test]
+ fn set_feature_bits() {
+ let mut features = InvoiceFeatures::empty();
+ features.set_basic_mpp_optional();
+ features.set_payment_secret_required();
+ assert!(features.supports_basic_mpp());
+ assert!(!features.requires_basic_mpp());
+ assert!(features.requires_payment_secret());
+ assert!(features.supports_payment_secret());
+ }
+
+ #[test]
+ fn invoice_features_encoding() {
+ let features_as_u5s = vec![
+ u5::try_from_u8(6).unwrap(),
+ u5::try_from_u8(10).unwrap(),
+ u5::try_from_u8(25).unwrap(),
+ u5::try_from_u8(1).unwrap(),
+ u5::try_from_u8(10).unwrap(),
+ u5::try_from_u8(0).unwrap(),
+ u5::try_from_u8(20).unwrap(),
+ u5::try_from_u8(2).unwrap(),
+ u5::try_from_u8(0).unwrap(),
+ u5::try_from_u8(6).unwrap(),
+ u5::try_from_u8(0).unwrap(),
+ u5::try_from_u8(16).unwrap(),
+ u5::try_from_u8(1).unwrap(),
+ ];
+ let features = InvoiceFeatures::from_le_bytes(vec![1, 2, 3, 4, 5, 42, 100, 101]);
+
+ // Test length calculation.
+ assert_eq!(features.base32_len(), 13);
+
+ // Test serialization.
+ let features_serialized = features.to_base32();
+ assert_eq!(features_as_u5s, features_serialized);
+
+ // Test deserialization.
+ let features_deserialized = InvoiceFeatures::from_base32(&features_as_u5s).unwrap();
+ assert_eq!(features, features_deserialized);
+ }
+
+ #[test]
+ fn test_channel_type_mapping() {
+ // If we map an InvoiceFeatures with StaticRemoteKey optional, it should map into a
+ // required-StaticRemoteKey ChannelTypeFeatures.
+ let mut init_features = InitFeatures::empty();
+ init_features.set_static_remote_key_optional();
+ let converted_features = ChannelTypeFeatures::from_counterparty_init(&init_features);
+ assert_eq!(converted_features, ChannelTypeFeatures::only_static_remote_key());
+ assert!(!converted_features.supports_any_optional_bits());
+ assert!(converted_features.requires_static_remote_key());
}
}