X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Ffeatures.rs;h=e9e12b3517458bce06738065ae2921b63f96b21d;hb=491bbc56cfcfa5c62c79113d1af2d17c37fbb75d;hp=4f45b9338c62c4e84c03e5223abcb248717e195e;hpb=a3ddb9fb19f68584c1724328931afbef37e9f172;p=rust-lightning

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index 4f45b933..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 {}
@@ -19,20 +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 {}
+	/// 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 InitialRoutingSync: Context {}
-	impl InitialRoutingSync for InitContext {}
+			$(
+				impl $feature for $context {
+					// EVEN_BIT % 2 == 0
+					const ASSERT_EVEN_BIT_PARITY: usize = 0 - (<Self as $feature>::EVEN_BIT % 2);
 
-	pub trait UpfrontShutdownScript: Context {}
-	impl UpfrontShutdownScript for InitContext {}
-	impl UpfrontShutdownScript for NodeContext {}
+					// ODD_BIT % 2 == 1
+					const ASSERT_ODD_BIT_PARITY: usize = (<Self as $feature>::ODD_BIT % 2) - 1;
+				}
+			)*
+		}
+	}
 
-	pub trait VariableLengthOnion: Context {}
-	impl VariableLengthOnion for InitContext {}
-	impl VariableLengthOnion 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
@@ -73,7 +166,11 @@ impl InitFeatures {
 	/// Create a Features with the features we support
 	pub fn supported() -> InitFeatures {
 		InitFeatures {
-			flags: vec![2 | 1 << 5, 1 << (9-8)],
+			flags: vec![
+				feature_flags![sealed::InitContext; DataLossProtect | InitialRoutingSync | UpfrontShutdownScript],
+				feature_flags![sealed::InitContext; VariableLengthOnion | PaymentSecret],
+				feature_flags![sealed::InitContext; BasicMPP],
+			],
 			mark: PhantomData,
 		}
 	}
@@ -136,25 +233,51 @@ impl NodeFeatures {
 	#[cfg(not(feature = "fuzztarget"))]
 	pub(crate) fn supported() -> NodeFeatures {
 		NodeFeatures {
-			flags: vec![2 | 1 << 5, 1 << (9-8)],
+			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)],
+			flags: vec![
+				feature_flags![sealed::NodeContext; DataLossProtect | UpfrontShutdownScript],
+				feature_flags![sealed::NodeContext; VariableLengthOnion | PaymentSecret],
+				feature_flags![sealed::NodeContext; BasicMPP],
+			],
 			mark: PhantomData,
 		}
 	}
 
 	/// 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.
+	/// 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();
-		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);
+		for (i, feature_byte)in init_ctx.flags.iter().enumerate() {
+			match i {
+				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]),
+				_ => (),
+			}
 		}
 		Self { flags, mark: PhantomData, }
 	}
@@ -185,29 +308,47 @@ impl<T: sealed::Context> Features<T> {
 	}
 
 	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),
-				// unknown, unknown, unknown, var_onion_optin:
-				1 => (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),
-				// unknown, unknown, unknown, var_onion_optin:
-				1 => (byte & 0b11111100),
+				0 => (byte & features_excluding![DataLossProtect | InitialRoutingSync | UpfrontShutdownScript]),
+				1 => (byte & features_excluding![VariableLengthOnion | PaymentSecret]),
+				2 => (byte & features_excluding![BasicMPP]),
 				_ => byte,
 			}) != 0
 		})
@@ -221,16 +362,19 @@ impl<T: sealed::Context> Features<T> {
 
 	#[cfg(test)]
 	pub(crate) fn set_require_unknown_bits(&mut self) {
-		let newlen = cmp::max(2, self.flags.len());
+		let newlen = cmp::max(3, self.flags.len());
 		self.flags.resize(newlen, 0u8);
-		self.flags[1] |= 0x40;
+		self.flags[2] |= 0x40;
 	}
 
 	#[cfg(test)]
 	pub(crate) fn clear_require_unknown_bits(&mut self) {
-		let newlen = cmp::max(2, self.flags.len());
+		let newlen = cmp::max(3, self.flags.len());
 		self.flags.resize(newlen, 0u8);
-		self.flags[1] &= !0x40;
+		self.flags[2] &= !0x40;
+		if self.flags.len() == 3 && self.flags[2] == 0 {
+			self.flags.resize(2, 0u8);
+		}
 		if self.flags.len() == 2 && self.flags[1] == 0 {
 			self.flags.resize(1, 0u8);
 		}
@@ -239,36 +383,50 @@ impl<T: sealed::Context> Features<T> {
 
 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 set_initial_routing_sync(&mut self) {
-		if self.flags.len() == 0 {
-			self.flags.resize(1, 1 << 3);
-		} else {
-			self.flags[0] |= 1 << 3;
-		}
+	pub(crate) fn clear_initial_routing_sync(&mut self) {
+		<T as sealed::InitialRoutingSync>::clear_optional_bit(&mut self.flags)
+	}
+}
+
+impl<T: sealed::PaymentSecret> Features<T> {
+	#[allow(dead_code)]
+	// Note that we never need to test this since what really matters is the invoice - iff the
+	// 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 {
+		<T as sealed::PaymentSecret>::supports_feature(&self.flags)
+	}
+}
+
+impl<T: sealed::BasicMPP> Features<T> {
+	// 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 {
+		<T as sealed::BasicMPP>::supports_feature(&self.flags)
 	}
 }
 
@@ -283,8 +441,8 @@ impl<T: sealed::Context> Writeable for Features<T> {
 	}
 }
 
-impl<R: ::std::io::Read, T: sealed::Context> Readable<R> for Features<T> {
-	fn read(r: &mut R) -> Result<Self, DecodeError> {
+impl<T: sealed::Context> Readable for Features<T> {
+	fn read<R: ::std::io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 		let mut flags: Vec<u8> = Readable::read(r)?;
 		flags.reverse(); // Swap to little-endian
 		Ok(Self {
@@ -293,3 +451,71 @@ impl<R: ::std::io::Read, T: sealed::Context> Readable<R> for Features<T> {
 		})
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use super::{ChannelFeatures, InitFeatures, NodeFeatures, Features};
+
+	#[test]
+	fn sanity_test_our_features() {
+		assert!(!ChannelFeatures::supported().requires_unknown_bits());
+		assert!(!ChannelFeatures::supported().supports_unknown_bits());
+		assert!(!InitFeatures::supported().requires_unknown_bits());
+		assert!(!InitFeatures::supported().supports_unknown_bits());
+		assert!(!NodeFeatures::supported().requires_unknown_bits());
+		assert!(!NodeFeatures::supported().supports_unknown_bits());
+
+		assert!(InitFeatures::supported().supports_upfront_shutdown_script());
+		assert!(NodeFeatures::supported().supports_upfront_shutdown_script());
+
+		assert!(InitFeatures::supported().supports_data_loss_protect());
+		assert!(NodeFeatures::supported().supports_data_loss_protect());
+
+		assert!(InitFeatures::supported().supports_variable_length_onion());
+		assert!(NodeFeatures::supported().supports_variable_length_onion());
+
+		assert!(InitFeatures::supported().supports_payment_secret());
+		assert!(NodeFeatures::supported().supports_payment_secret());
+
+		assert!(InitFeatures::supported().supports_basic_mpp());
+		assert!(NodeFeatures::supported().supports_basic_mpp());
+
+		let mut init_features = InitFeatures::supported();
+		assert!(init_features.initial_routing_sync());
+		init_features.clear_initial_routing_sync();
+		assert!(!init_features.initial_routing_sync());
+	}
+
+	#[test]
+	fn sanity_test_unkown_bits_testing() {
+		let mut features = ChannelFeatures::supported();
+		features.set_require_unknown_bits();
+		assert!(features.requires_unknown_bits());
+		features.clear_require_unknown_bits();
+		assert!(!features.requires_unknown_bits());
+	}
+
+	#[test]
+	fn test_node_with_known_relevant_init_flags() {
+		// Create an InitFeatures with initial_routing_sync supported.
+		let init_features = InitFeatures::supported();
+		assert!(init_features.initial_routing_sync());
+
+		// Attempt to pull out non-node-context feature flags from these InitFeatures.
+		let res = NodeFeatures::with_known_relevant_init_flags(&init_features);
+
+		{
+			// Check that the flags are as expected: optional_data_loss_protect,
+			// option_upfront_shutdown_script, var_onion_optin, payment_secret, and
+			// basic_mpp.
+			assert_eq!(res.flags.len(), 3);
+			assert_eq!(res.flags[0], 0b00100010);
+			assert_eq!(res.flags[1], 0b10000010);
+			assert_eq!(res.flags[2], 0b00000010);
+		}
+
+		// Check that the initial_routing_sync feature was correctly blanked out.
+		let new_features: InitFeatures = Features::from_le_bytes(res.flags);
+		assert!(!new_features.initial_routing_sync());
+	}
+}