f add channeltypefeatures

Author: TheBlueMatt

lightning/src/ln/features.rs

@@ -482,7 +482,14 @@ 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 {
-		counterparty_init.to_context_internal()
+		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
 	}
 
 	/// Constructs a ChannelTypeFeatures with only static_remotekey set
@@ -619,6 +626,10 @@ impl<T: sealed::Context> Features<T> {
 		}
 	}
 
+	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 {
@@ -795,7 +806,7 @@ impl Readable for ChannelTypeFeatures {
 
 #[cfg(test)]
 mod tests {
-	use super::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
+	use super::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
 	use bitcoin::bech32::{Base32Len, FromBase32, ToBase32, u5};
 
 	#[test]
@@ -954,4 +965,15 @@ mod tests {
 		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 init_features = InitFeatures::empty().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());
+	}
 }