X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Ffeatures.rs;h=613d2db14590b5115b9ae6c18461699141dd0c19;hb=b1c6499e1c50fc41c443883dde8e8248106089c3;hp=0dd5fa3049364a853c99ce34fe69d226a8dab689;hpb=65ff1bf0beaeb33397c5024d278a65a780fc8ffd;p=rust-lightning

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index 0dd5fa30..613d2db1 100644
--- a/lightning/src/ln/features.rs
+++ b/lightning/src/ln/features.rs
@@ -173,6 +173,16 @@ mod sealed {
 						(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);
+					}
+
+					flags[Self::BYTE_OFFSET] |= Self::REQUIRED_MASK;
+				}
+
 				/// Sets the feature's optional (odd) bit in the given flags.
 				#[inline]
 				fn set_optional_bit(flags: &mut Vec<u8>) {
@@ -191,6 +201,10 @@ mod sealed {
 						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);
 				}
 			}
 
@@ -219,6 +233,30 @@ mod sealed {
 		"Feature flags for `payment_secret`.");
 	define_feature!(17, BasicMPP, [InitContext, NodeContext],
 		"Feature flags for `basic_mpp`.");
+
+	#[cfg(test)]
+	define_context!(TestingContext {
+		required_features: [
+			// Byte 0
+			,
+			// Byte 1
+			,
+			// Byte 2
+			UnknownFeature,
+		],
+		optional_features: [
+			// Byte 0
+			,
+			// Byte 1
+			,
+			// Byte 2
+			,
+		],
+	});
+
+	#[cfg(test)]
+	define_feature!(23, UnknownFeature, [TestingContext],
+		"Feature flags for an unknown feature used in testing.");
 }
 
 /// Tracks the set of features which a node implements, templated by the context in which it
@@ -282,6 +320,12 @@ impl InitFeatures {
 		}
 		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<T: sealed::Context> Features<T> {
@@ -303,18 +347,19 @@ impl<T: sealed::Context> Features<T> {
 		}
 	}
 
-	/// 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 {
-		let byte_count = T::KNOWN_FEATURE_MASK.len();
+	/// 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 byte_count = C::KNOWN_FEATURE_MASK.len();
 		let mut flags = Vec::new();
-		for (i, feature_byte) in init_ctx.flags.iter().enumerate() {
+		for (i, byte) in self.flags.iter().enumerate() {
 			if i < byte_count {
-				flags.push(feature_byte & T::KNOWN_FEATURE_MASK[i]);
+				let known_source_features = T::KNOWN_FEATURE_MASK[i];
+				let known_target_features = C::KNOWN_FEATURE_MASK[i];
+				flags.push(byte & known_source_features & known_target_features);
 			}
 		}
-		Self { flags, mark: PhantomData, }
+		Features::<C> { flags, mark: PhantomData, }
 	}
 
 	#[cfg(test)]
@@ -368,23 +413,18 @@ impl<T: sealed::Context> Features<T> {
 	}
 
 	#[cfg(test)]
-	pub(crate) fn set_require_unknown_bits(&mut self) {
-		let newlen = cmp::max(3, self.flags.len());
-		self.flags.resize(newlen, 0u8);
-		self.flags[2] |= 0x40;
+	pub(crate) fn set_required_unknown_bits(&mut self) {
+		<sealed::TestingContext as sealed::UnknownFeature>::set_required_bit(&mut self.flags);
 	}
 
 	#[cfg(test)]
-	pub(crate) fn clear_require_unknown_bits(&mut self) {
-		let newlen = cmp::max(3, self.flags.len());
-		self.flags.resize(newlen, 0u8);
-		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);
-		}
+	pub(crate) fn set_optional_unknown_bits(&mut self) {
+		<sealed::TestingContext as sealed::UnknownFeature>::set_optional_bit(&mut self.flags);
+	}
+
+	#[cfg(test)]
+	pub(crate) fn clear_unknown_bits(&mut self) {
+		<sealed::TestingContext as sealed::UnknownFeature>::clear_bits(&mut self.flags);
 	}
 }
 
@@ -399,8 +439,9 @@ impl<T: sealed::UpfrontShutdownScript> Features<T> {
 		<T as sealed::UpfrontShutdownScript>::supports_feature(&self.flags)
 	}
 	#[cfg(test)]
-	pub(crate) fn unset_upfront_shutdown_script(&mut self) {
-		<T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags)
+	pub(crate) fn clear_upfront_shutdown_script(mut self) -> Self {
+		<T as sealed::UpfrontShutdownScript>::clear_bits(&mut self.flags);
+		self
 	}
 }
 
@@ -461,7 +502,7 @@ impl<T: sealed::Context> Readable for Features<T> {
 
 #[cfg(test)]
 mod tests {
-	use super::{ChannelFeatures, InitFeatures, NodeFeatures, Features};
+	use super::{ChannelFeatures, InitFeatures, NodeFeatures};
 
 	#[test]
 	fn sanity_test_our_features() {
@@ -494,35 +535,47 @@ mod tests {
 	}
 
 	#[test]
-	fn sanity_test_unkown_bits_testing() {
-		let mut features = ChannelFeatures::known();
-		features.set_require_unknown_bits();
+	fn sanity_test_unknown_bits() {
+		let mut features = ChannelFeatures::empty();
+		assert!(!features.requires_unknown_bits());
+		assert!(!features.supports_unknown_bits());
+
+		features.set_required_unknown_bits();
 		assert!(features.requires_unknown_bits());
-		features.clear_require_unknown_bits();
+		assert!(features.supports_unknown_bits());
+
+		features.clear_unknown_bits();
 		assert!(!features.requires_unknown_bits());
+		assert!(!features.supports_unknown_bits());
+
+		features.set_optional_unknown_bits();
+		assert!(!features.requires_unknown_bits());
+		assert!(features.supports_unknown_bits());
 	}
 
 	#[test]
-	fn test_node_with_known_relevant_init_flags() {
-		// Create an InitFeatures with initial_routing_sync supported.
-		let init_features = InitFeatures::known();
+	fn convert_to_context_with_relevant_flags() {
+		let init_features = InitFeatures::known().clear_upfront_shutdown_script();
 		assert!(init_features.initial_routing_sync());
+		assert!(!init_features.supports_upfront_shutdown_script());
 
-		// Attempt to pull out non-node-context feature flags from these InitFeatures.
-		let res = NodeFeatures::with_known_relevant_init_flags(&init_features);
-
+		let node_features: NodeFeatures = init_features.to_context();
 		{
-			// 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 flags are as expected:
+			// - option_data_loss_protect
+			// - var_onion_optin | payment_secret
+			// - basic_mpp
+			assert_eq!(node_features.flags.len(), 3);
+			assert_eq!(node_features.flags[0], 0b00000010);
+			assert_eq!(node_features.flags[1], 0b10000010);
+			assert_eq!(node_features.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());
+		// 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
+		let features: InitFeatures = node_features.to_context_internal();
+		assert!(!features.initial_routing_sync());
+		assert!(!features.supports_upfront_shutdown_script());
 	}
 }