X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Ffeatures.rs;h=4b49a56eacf73d5f4fe39c033a2206affbd889db;hb=3313abb37d8745597c7fe8aeaa230f4e89160e02;hp=cf375603b37b5290aaf10250218f4b66cce0678a;hpb=2e15df730ff5668ee37678bf7c355b60cdc6cbe8;p=rust-lightning

diff --git a/lightning/src/ln/features.rs b/lightning/src/ln/features.rs
index cf375603..4b49a56e 100644
--- a/lightning/src/ln/features.rs
+++ b/lightning/src/ln/features.rs
@@ -422,8 +422,10 @@ pub struct Features<T: sealed::Context> {
 	mark: PhantomData<T>,
 }
 
-impl <T: sealed::Context> Features<T> {
-	pub(crate) fn or(mut self, o: Self) -> Self {
+impl<T: sealed::Context> core::ops::BitOr for Features<T> {
+	type Output = Self;
+
+	fn bitor(mut self, o: Self) -> Self {
 		let total_feature_len = cmp::max(self.flags.len(), o.flags.len());
 		self.flags.resize(total_feature_len, 0u8);
 		for (byte, o_byte) in self.flags.iter_mut().zip(o.flags.iter()) {
@@ -677,6 +679,25 @@ impl<T: sealed::Context> Features<T> {
 		self.flags.iter().any(|&byte| (byte & 0b10_10_10_10) != 0)
 	}
 
+	/// Returns true if this `Features` object contains required features unknown by `other`.
+	pub fn requires_unknown_bits_from(&self, other: &Features<T>) -> bool {
+		// Bitwise AND-ing with all even bits set except for known features will select required
+		// unknown features.
+		self.flags.iter().enumerate().any(|(i, &byte)| {
+			const REQUIRED_FEATURES: u8 = 0b01_01_01_01;
+			const OPTIONAL_FEATURES: u8 = 0b10_10_10_10;
+			let unknown_features = if i < other.flags.len() {
+				// Form a mask similar to !T::KNOWN_FEATURE_MASK only for `other`
+				!(other.flags[i]
+					| ((other.flags[i] >> 1) & REQUIRED_FEATURES)
+					| ((other.flags[i] << 1) & OPTIONAL_FEATURES))
+			} else {
+				0b11_11_11_11
+			};
+			(byte & (REQUIRED_FEATURES & unknown_features)) != 0
+		})
+	}
+
 	/// Returns true if this `Features` object contains unknown feature flags which are set as
 	/// "required".
 	pub fn requires_unknown_bits(&self) -> bool {
@@ -850,13 +871,50 @@ mod tests {
 		assert!(features.supports_unknown_bits());
 	}
 
+	#[test]
+	fn requires_unknown_bits_from() {
+		let mut features1 = InitFeatures::empty();
+		let mut features2 = InitFeatures::empty();
+		assert!(!features1.requires_unknown_bits_from(&features2));
+		assert!(!features2.requires_unknown_bits_from(&features1));
+
+		features1.set_data_loss_protect_required();
+		assert!(features1.requires_unknown_bits_from(&features2));
+		assert!(!features2.requires_unknown_bits_from(&features1));
+
+		features2.set_data_loss_protect_optional();
+		assert!(!features1.requires_unknown_bits_from(&features2));
+		assert!(!features2.requires_unknown_bits_from(&features1));
+
+		features2.set_gossip_queries_required();
+		assert!(!features1.requires_unknown_bits_from(&features2));
+		assert!(features2.requires_unknown_bits_from(&features1));
+
+		features1.set_gossip_queries_optional();
+		assert!(!features1.requires_unknown_bits_from(&features2));
+		assert!(!features2.requires_unknown_bits_from(&features1));
+
+		features1.set_variable_length_onion_required();
+		assert!(features1.requires_unknown_bits_from(&features2));
+		assert!(!features2.requires_unknown_bits_from(&features1));
+
+		features2.set_variable_length_onion_optional();
+		assert!(!features1.requires_unknown_bits_from(&features2));
+		assert!(!features2.requires_unknown_bits_from(&features1));
+
+		features1.set_basic_mpp_required();
+		features2.set_wumbo_required();
+		assert!(features1.requires_unknown_bits_from(&features2));
+		assert!(features2.requires_unknown_bits_from(&features1));
+	}
+
 	#[test]
 	fn convert_to_context_with_relevant_flags() {
 		let mut init_features = InitFeatures::empty();
 		// Set a bunch of features we use, plus initial_routing_sync_required (which shouldn't get
 		// converted as it's only relevant in an init context).
 		init_features.set_initial_routing_sync_required();
-		init_features.set_data_loss_protect_optional();
+		init_features.set_data_loss_protect_required();
 		init_features.set_variable_length_onion_required();
 		init_features.set_static_remote_key_required();
 		init_features.set_payment_secret_required();
@@ -876,7 +934,7 @@ mod tests {
 		let node_features: NodeFeatures = init_features.to_context();
 		{
 			// Check that the flags are as expected:
-			// - option_data_loss_protect
+			// - option_data_loss_protect (req)
 			// - var_onion_optin (req) | static_remote_key (req) | payment_secret(req)
 			// - basic_mpp | wumbo
 			// - opt_shutdown_anysegwit
@@ -884,7 +942,7 @@ mod tests {
 			// - option_channel_type | option_scid_alias
 			// - option_zeroconf
 			assert_eq!(node_features.flags.len(), 7);
-			assert_eq!(node_features.flags[0], 0b00000010);
+			assert_eq!(node_features.flags[0], 0b00000001);
 			assert_eq!(node_features.flags[1], 0b01010001);
 			assert_eq!(node_features.flags[2], 0b10001010);
 			assert_eq!(node_features.flags[3], 0b00001000);