X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Ffeatures.rs;h=28710c343649e813f5e9581f9fad5fa618c4430b;hb=b530cdc25227acf512b6cf32ac4fcf815c67dff9;hp=bcaa91ab266fe7f10ebbc8de710fc30d927365c3;hpb=3141630f78a0f1ec7ef374ede95a21e4e64213f5;p=rust-lightning

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index bcaa91ab2..28710c343 100644
--- a/lightning/src/ln/features.rs
+++ b/lightning/src/ln/features.rs
@@ -718,7 +718,11 @@ impl<T: sealed::Context> Features<T> {
 		Ok(())
 	}
 
-	fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
+	/// Create a [`Features`] given a set of flags, in big-endian. This is in byte order from
+	/// most on-the-wire encodings.
+	///
+	/// This is not exported to bindings users as we don't support export across multiple T
+	pub fn from_be_bytes(mut flags: Vec<u8>) -> Features<T> {
 		flags.reverse(); // Swap to little-endian
 		Self {
 			flags,
@@ -754,16 +758,23 @@ impl<T: sealed::Context> Features<T> {
 	pub fn requires_unknown_bits(&self) -> bool {
 		// Bitwise AND-ing with all even bits set except for known features will select required
 		// unknown features.
-		let byte_count = T::KNOWN_FEATURE_MASK.len();
-		self.flags.iter().enumerate().any(|(i, &byte)| {
-			let required_features = 0b01_01_01_01;
-			let unknown_features = if i < byte_count {
-				!T::KNOWN_FEATURE_MASK[i]
-			} else {
-				0b11_11_11_11
-			};
-			(byte & (required_features & unknown_features)) != 0
-		})
+		let mut known_chunks = T::KNOWN_FEATURE_MASK.chunks(8);
+		for chunk in self.flags.chunks(8) {
+			let mut flag_bytes = [0; 8];
+			flag_bytes[..chunk.len()].copy_from_slice(&chunk);
+			let flag_int = u64::from_le_bytes(flag_bytes);
+
+			let known_chunk = known_chunks.next().unwrap_or(&[0; 0]);
+			let mut known_bytes = [0; 8];
+			known_bytes[..known_chunk.len()].copy_from_slice(&known_chunk);
+			let known_int = u64::from_le_bytes(known_bytes);
+
+			const REQ_MASK: u64 = 0x55555555_55555555;
+			if flag_int & (REQ_MASK & !known_int) != 0 {
+				return true;
+			}
+		}
+		false
 	}
 
 	pub(crate) fn supports_unknown_bits(&self) -> bool {