X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=rust-lightning;a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Ffeatures.rs;h=e9e12b3517458bce06738065ae2921b63f96b21d;hp=f6912662497fb33f712838f40c907b8cf65e4235;hb=491bbc56cfcfa5c62c79113d1af2d17c37fbb75d;hpb=07cea6bfeda1641c2a1440f4e4847c747507c4f0 diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs index f6912662..e9e12b35 100644 --- a/lightning/src/ln/features.rs +++ b/lightning/src/ln/features.rs @@ -8,6 +8,7 @@ use std::marker::PhantomData; 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 {} @@ -19,28 +20,112 @@ mod sealed { // You should just use the type aliases instead. 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) -> 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) { + 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) { + 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 $context { + // EVEN_BIT % 2 == 0 + const ASSERT_EVEN_BIT_PARITY: usize = 0 - (::EVEN_BIT % 2); - pub trait PaymentSecret: Context {} - impl PaymentSecret for InitContext {} - impl PaymentSecret for NodeContext {} + // ODD_BIT % 2 == 1 + const ASSERT_ODD_BIT_PARITY: usize = (::ODD_BIT % 2) - 1; + } + )* + } + } - pub trait BasicMPP: Context {} - impl BasicMPP for InitContext {} - impl BasicMPP for NodeContext {} + define_feature!(1, DataLossProtect, [InitContext, NodeContext], + "Feature flags for `option_data_loss_protect`."); + // NOTE: Per Bolt #9, initial_routing_sync has no even bit. + define_feature!(3, InitialRoutingSync, [InitContext], + "Feature flags for `initial_routing_sync`."); + define_feature!(5, UpfrontShutdownScript, [InitContext, NodeContext], + "Feature flags for `option_upfront_shutdown_script`."); + define_feature!(9, VariableLengthOnion, [InitContext, NodeContext], + "Feature flags for `var_onion_optin`."); + define_feature!(15, PaymentSecret, [InitContext, NodeContext], + "Feature flags for `payment_secret`."); + define_feature!(17, BasicMPP, [InitContext, NodeContext], + "Feature flags for `basic_mpp`."); + + /// Generates a feature flag byte with the given features set as optional. Useful for initializing + /// the flags within [`Features`]. + /// + /// [`Features`]: struct.Features.html + macro_rules! feature_flags { + ($context: ty; $($feature: ident)|*) => { + (0b00_00_00_00 + $( + | <$context as sealed::$feature>::OPTIONAL_MASK + )* + ) + } + } } /// Tracks the set of features which a node implements, templated by the context in which it @@ -81,7 +166,11 @@ impl InitFeatures { /// Create a Features with the features we support pub fn supported() -> InitFeatures { InitFeatures { - flags: vec![2 | 1 << 3 | 1 << 5, 1 << (9-8) | 1 << (15 - 8), 1 << (17 - 8*2)], + flags: vec![ + feature_flags![sealed::InitContext; DataLossProtect | InitialRoutingSync | UpfrontShutdownScript], + feature_flags![sealed::InitContext; VariableLengthOnion | PaymentSecret], + feature_flags![sealed::InitContext; BasicMPP], + ], mark: PhantomData, } } @@ -144,14 +233,22 @@ impl NodeFeatures { #[cfg(not(feature = "fuzztarget"))] pub(crate) fn supported() -> NodeFeatures { NodeFeatures { - flags: vec![2 | 1 << 5, 1 << (9 - 8) | 1 << (15 - 8), 1 << (17 - 8*2)], + flags: vec![ + feature_flags![sealed::NodeContext; DataLossProtect | UpfrontShutdownScript], + feature_flags![sealed::NodeContext; VariableLengthOnion | PaymentSecret], + feature_flags![sealed::NodeContext; BasicMPP], + ], mark: PhantomData, } } #[cfg(feature = "fuzztarget")] pub fn supported() -> NodeFeatures { NodeFeatures { - flags: vec![2 | 1 << 5, 1 << (9 - 8) | 1 << (15 - 8), 1 << (17 - 8*2)], + flags: vec![ + feature_flags![sealed::NodeContext; DataLossProtect | UpfrontShutdownScript], + feature_flags![sealed::NodeContext; VariableLengthOnion | PaymentSecret], + feature_flags![sealed::NodeContext; BasicMPP], + ], mark: PhantomData, } } @@ -160,15 +257,25 @@ impl NodeFeatures { /// relevant in a node-context features and creates a node-context features from them. /// Be sure to blank out features that are unknown to us. pub(crate) fn with_known_relevant_init_flags(init_ctx: &InitFeatures) -> Self { + // Generates a bitmask with both even and odd bits set for the given features. Bitwise + // AND-ing it with a byte will select only common features. + macro_rules! features_including { + ($($feature: ident)|*) => { + (0b00_00_00_00 + $( + | ::REQUIRED_MASK + | ::OPTIONAL_MASK + )* + ) + } + } + let mut flags = Vec::new(); for (i, feature_byte)in init_ctx.flags.iter().enumerate() { match i { - // Blank out initial_routing_sync (feature bits 2/3), gossip_queries (6/7), - // gossip_queries_ex (10/11), option_static_remotekey (12/13), and - // option_support_large_channel (16/17) - 0 => flags.push(feature_byte & 0b00110011), - 1 => flags.push(feature_byte & 0b11000011), - 2 => flags.push(feature_byte & 0b00000011), + 0 => flags.push(feature_byte & features_including![DataLossProtect | UpfrontShutdownScript]), + 1 => flags.push(feature_byte & features_including![VariableLengthOnion | PaymentSecret]), + 2 => flags.push(feature_byte & features_including![BasicMPP]), _ => (), } } @@ -201,33 +308,47 @@ impl Features { } pub(crate) fn requires_unknown_bits(&self) -> bool { + // Generates a bitmask with all even bits set except for the given features. Bitwise + // AND-ing it with a byte will select unknown required features. + macro_rules! features_excluding { + ($($feature: ident)|*) => { + (0b01_01_01_01 + $( + & !(::REQUIRED_MASK) + )* + ) + } + } + self.flags.iter().enumerate().any(|(idx, &byte)| { (match idx { - // Unknown bits are even bits which we don't understand, we list ones which we do - // here: - // unknown, upfront_shutdown_script, unknown (actually initial_routing_sync, but it - // is only valid as an optional feature), and data_loss_protect: - 0 => (byte & 0b01000100), - // payment_secret, unknown, unknown, var_onion_optin: - 1 => (byte & 0b00010100), - // unknown, unknown, unknown, basic_mpp: - 2 => (byte & 0b01010100), - // fallback, all even bits set: - _ => (byte & 0b01010101), + 0 => (byte & features_excluding![DataLossProtect | InitialRoutingSync | UpfrontShutdownScript]), + 1 => (byte & features_excluding![VariableLengthOnion | PaymentSecret]), + 2 => (byte & features_excluding![BasicMPP]), + _ => (byte & features_excluding![]), }) != 0 }) } pub(crate) fn supports_unknown_bits(&self) -> bool { + // Generates a bitmask with all even and odd bits set except for the given features. Bitwise + // AND-ing it with a byte will select unknown supported features. + macro_rules! features_excluding { + ($($feature: ident)|*) => { + (0b11_11_11_11 + $( + & !(::REQUIRED_MASK) + & !(::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 }) @@ -262,34 +383,32 @@ impl Features { impl Features { pub(crate) fn supports_data_loss_protect(&self) -> bool { - self.flags.len() > 0 && (self.flags[0] & 3) != 0 + ::supports_feature(&self.flags) } } impl Features { pub(crate) fn supports_upfront_shutdown_script(&self) -> bool { - self.flags.len() > 0 && (self.flags[0] & (3 << 4)) != 0 + ::supports_feature(&self.flags) } #[cfg(test)] pub(crate) fn unset_upfront_shutdown_script(&mut self) { - self.flags[0] &= !(1 << 5); + ::clear_optional_bit(&mut self.flags) } } impl Features { pub(crate) fn supports_variable_length_onion(&self) -> bool { - self.flags.len() > 1 && (self.flags[1] & 3) != 0 + ::supports_feature(&self.flags) } } impl Features { pub(crate) fn initial_routing_sync(&self) -> bool { - self.flags.len() > 0 && (self.flags[0] & (1 << 3)) != 0 + ::supports_feature(&self.flags) } pub(crate) fn clear_initial_routing_sync(&mut self) { - if self.flags.len() > 0 { - self.flags[0] &= !(1 << 3); - } + ::clear_optional_bit(&mut self.flags) } } @@ -299,7 +418,7 @@ impl Features { // 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 + ::supports_feature(&self.flags) } } @@ -307,7 +426,7 @@ impl Features { // 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 + ::supports_feature(&self.flags) } }