use ln::msgs::DecodeError;
use util::ser::{Readable, Writeable, Writer};
+#[macro_use]
mod sealed { // You should just use the type aliases instead.
pub struct InitContext {}
pub struct NodeContext {}
impl Context for NodeContext {}
impl Context for ChannelContext {}
- pub trait DataLossProtect: Context {}
- impl DataLossProtect for InitContext {}
- impl DataLossProtect for NodeContext {}
-
- pub trait InitialRoutingSync: Context {}
- impl InitialRoutingSync for InitContext {}
-
- pub trait UpfrontShutdownScript: Context {}
- impl UpfrontShutdownScript for InitContext {}
- impl UpfrontShutdownScript for NodeContext {}
+ /// Defines a feature with the given bits for the specified [`Context`]s. The generated trait is
+ /// useful for manipulating feature flags.
+ ///
+ /// [`Context`]: trait.Context.html
+ macro_rules! define_feature {
+ ($odd_bit: expr, $feature: ident, [$($context: ty),+], $doc: expr) => {
+ #[doc = $doc]
+ ///
+ /// See [BOLT #9] for details.
+ ///
+ /// [BOLT #9]: https://github.com/lightningnetwork/lightning-rfc/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;
+
+ /// 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 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 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 optional (odd) bit from the given flags.
+ #[inline]
+ fn clear_optional_bit(flags: &mut Vec<u8>) {
+ if flags.len() > Self::BYTE_OFFSET {
+ flags[Self::BYTE_OFFSET] &= !Self::OPTIONAL_MASK;
+ }
+ }
+ }
- pub trait VariableLengthOnion: Context {}
- impl VariableLengthOnion for InitContext {}
- impl VariableLengthOnion for NodeContext {}
+ $(
+ impl $feature for $context {
+ // EVEN_BIT % 2 == 0
+ const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
- pub trait PaymentSecret: Context {}
- impl PaymentSecret for InitContext {}
- impl PaymentSecret for NodeContext {}
+ // ODD_BIT % 2 == 1
+ const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
+ }
+ )*
+ }
+ }
- pub trait BasicMPP: Context {}
- impl BasicMPP for InitContext {}
- impl BasicMPP for NodeContext {}
+ define_feature!(1, DataLossProtect, [InitContext, NodeContext],
+ "Feature flags for `option_data_loss_protect`.");
+ // NOTE: Per Bolt #9, initial_routing_sync has no even bit.
+ define_feature!(3, InitialRoutingSync, [InitContext],
+ "Feature flags for `initial_routing_sync`.");
+ define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext],
+ "Feature flags for `option_upfront_shutdown_script`.");
+ define_feature!(9, VariableLengthOnion, [InitContext, NodeContext],
+ "Feature flags for `var_onion_optin`.");
+ define_feature!(15, PaymentSecret, [InitContext, NodeContext],
+ "Feature flags for `payment_secret`.");
+ define_feature!(17, BasicMPP, [InitContext, NodeContext],
+ "Feature flags for `basic_mpp`.");
+
+ /// Generates a feature flag byte with the given features set as optional. Useful for initializing
+ /// the flags within [`Features`].
+ ///
+ /// [`Features`]: struct.Features.html
+ macro_rules! feature_flags {
+ ($context: ty; $($feature: ident)|*) => {
+ (0b00_00_00_00
+ $(
+ | <$context as sealed::$feature>::OPTIONAL_MASK
+ )*
+ )
+ }
+ }
}
/// Tracks the set of features which a node implements, templated by the context in which it
/// Create a Features with the features we support
pub fn supported() -> InitFeatures {
InitFeatures {
- flags: vec![2 | 1 << 3 | 1 << 5, 1 << (9-8) | 1 << (15 - 8), 1 << (17 - 8*2)],
+ flags: vec![
+ feature_flags![sealed::InitContext; DataLossProtect | InitialRoutingSync | UpfrontShutdownScript],
+ feature_flags![sealed::InitContext; VariableLengthOnion | PaymentSecret],
+ feature_flags![sealed::InitContext; BasicMPP],
+ ],
mark: PhantomData,
}
}
#[cfg(not(feature = "fuzztarget"))]
pub(crate) fn supported() -> NodeFeatures {
NodeFeatures {
- flags: vec![2 | 1 << 5, 1 << (9 - 8) | 1 << (15 - 8), 1 << (17 - 8*2)],
+ flags: vec![
+ feature_flags![sealed::NodeContext; DataLossProtect | UpfrontShutdownScript],
+ feature_flags![sealed::NodeContext; VariableLengthOnion | PaymentSecret],
+ feature_flags![sealed::NodeContext; BasicMPP],
+ ],
mark: PhantomData,
}
}
#[cfg(feature = "fuzztarget")]
pub fn supported() -> NodeFeatures {
NodeFeatures {
- flags: vec![2 | 1 << 5, 1 << (9 - 8) | 1 << (15 - 8), 1 << (17 - 8*2)],
+ flags: vec![
+ feature_flags![sealed::NodeContext; DataLossProtect | UpfrontShutdownScript],
+ feature_flags![sealed::NodeContext; VariableLengthOnion | PaymentSecret],
+ feature_flags![sealed::NodeContext; BasicMPP],
+ ],
mark: PhantomData,
}
}
/// relevant in a node-context features and creates a node-context features from them.
/// Be sure to blank out features that are unknown to us.
pub(crate) fn with_known_relevant_init_flags(init_ctx: &InitFeatures) -> Self {
+ // Generates a bitmask with both even and odd bits set for the given features. Bitwise
+ // AND-ing it with a byte will select only common features.
+ macro_rules! features_including {
+ ($($feature: ident)|*) => {
+ (0b00_00_00_00
+ $(
+ | <sealed::NodeContext as sealed::$feature>::REQUIRED_MASK
+ | <sealed::NodeContext as sealed::$feature>::OPTIONAL_MASK
+ )*
+ )
+ }
+ }
+
let mut flags = Vec::new();
for (i, feature_byte)in init_ctx.flags.iter().enumerate() {
match i {
- // Blank out initial_routing_sync (feature bits 2/3), gossip_queries (6/7),
- // gossip_queries_ex (10/11), option_static_remotekey (12/13), and
- // option_support_large_channel (16/17)
- 0 => flags.push(feature_byte & 0b00110011),
- 1 => flags.push(feature_byte & 0b11000011),
- 2 => flags.push(feature_byte & 0b00000011),
+ 0 => flags.push(feature_byte & features_including![DataLossProtect | UpfrontShutdownScript]),
+ 1 => flags.push(feature_byte & features_including![VariableLengthOnion | PaymentSecret]),
+ 2 => flags.push(feature_byte & features_including![BasicMPP]),
_ => (),
}
}
}
pub(crate) fn requires_unknown_bits(&self) -> bool {
+ // Generates a bitmask with all even bits set except for the given features. Bitwise
+ // AND-ing it with a byte will select unknown required features.
+ macro_rules! features_excluding {
+ ($($feature: ident)|*) => {
+ (0b01_01_01_01
+ $(
+ & !(<sealed::InitContext as sealed::$feature>::REQUIRED_MASK)
+ )*
+ )
+ }
+ }
+
self.flags.iter().enumerate().any(|(idx, &byte)| {
(match idx {
- // Unknown bits are even bits which we don't understand, we list ones which we do
- // here:
- // unknown, upfront_shutdown_script, unknown (actually initial_routing_sync, but it
- // is only valid as an optional feature), and data_loss_protect:
- 0 => (byte & 0b01000100),
- // payment_secret, unknown, unknown, var_onion_optin:
- 1 => (byte & 0b00010100),
- // unknown, unknown, unknown, basic_mpp:
- 2 => (byte & 0b01010100),
- // fallback, all even bits set:
- _ => (byte & 0b01010101),
+ 0 => (byte & features_excluding![DataLossProtect | InitialRoutingSync | UpfrontShutdownScript]),
+ 1 => (byte & features_excluding![VariableLengthOnion | PaymentSecret]),
+ 2 => (byte & features_excluding![BasicMPP]),
+ _ => (byte & features_excluding![]),
}) != 0
})
}
pub(crate) fn supports_unknown_bits(&self) -> bool {
+ // Generates a bitmask with all even and odd bits set except for the given features. Bitwise
+ // AND-ing it with a byte will select unknown supported features.
+ macro_rules! features_excluding {
+ ($($feature: ident)|*) => {
+ (0b11_11_11_11
+ $(
+ & !(<sealed::InitContext as sealed::$feature>::REQUIRED_MASK)
+ & !(<sealed::InitContext as sealed::$feature>::OPTIONAL_MASK)
+ )*
+ )
+ }
+ }
+
self.flags.iter().enumerate().any(|(idx, &byte)| {
(match idx {
- // unknown, upfront_shutdown_script, initial_routing_sync (is only valid as an
- // optional feature), and data_loss_protect:
- 0 => (byte & 0b11000100),
- // payment_secret, unknown, unknown, var_onion_optin:
- 1 => (byte & 0b00111100),
- // unknown, unknown, unknown, basic_mpp:
- 2 => (byte & 0b11111100),
+ 0 => (byte & features_excluding![DataLossProtect | InitialRoutingSync | UpfrontShutdownScript]),
+ 1 => (byte & features_excluding![VariableLengthOnion | PaymentSecret]),
+ 2 => (byte & features_excluding![BasicMPP]),
_ => byte,
}) != 0
})
impl<T: sealed::DataLossProtect> Features<T> {
pub(crate) fn supports_data_loss_protect(&self) -> bool {
- self.flags.len() > 0 && (self.flags[0] & 3) != 0
+ <T as sealed::DataLossProtect>::supports_feature(&self.flags)
}
}
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
+ <T as sealed::UpfrontShutdownScript>::supports_feature(&self.flags)
}
#[cfg(test)]
pub(crate) fn unset_upfront_shutdown_script(&mut self) {
- self.flags[0] &= !(1 << 5);
+ <T as sealed::UpfrontShutdownScript>::clear_optional_bit(&mut self.flags)
}
}
impl<T: sealed::VariableLengthOnion> Features<T> {
pub(crate) fn supports_variable_length_onion(&self) -> bool {
- self.flags.len() > 1 && (self.flags[1] & 3) != 0
+ <T as sealed::VariableLengthOnion>::supports_feature(&self.flags)
}
}
impl<T: sealed::InitialRoutingSync> Features<T> {
pub(crate) fn initial_routing_sync(&self) -> bool {
- self.flags.len() > 0 && (self.flags[0] & (1 << 3)) != 0
+ <T as sealed::InitialRoutingSync>::supports_feature(&self.flags)
}
pub(crate) fn clear_initial_routing_sync(&mut self) {
- if self.flags.len() > 0 {
- self.flags[0] &= !(1 << 3);
- }
+ <T as sealed::InitialRoutingSync>::clear_optional_bit(&mut self.flags)
}
}
// invoice provides a payment_secret, we assume that we can use it (ie that the recipient
// supports payment_secret).
pub(crate) fn supports_payment_secret(&self) -> bool {
- self.flags.len() > 1 && (self.flags[1] & (3 << (14-8))) != 0
+ <T as sealed::PaymentSecret>::supports_feature(&self.flags)
}
}
// We currently never test for this since we don't actually *generate* multipath routes.
#[allow(dead_code)]
pub(crate) fn supports_basic_mpp(&self) -> bool {
- self.flags.len() > 2 && (self.flags[2] & (3 << (16-8*2))) != 0
+ <T as sealed::BasicMPP>::supports_feature(&self.flags)
}
}
projects / rust-lightning / commitdiff