Define the PaymentMetadata feature to be used in invoices

Author: TheBlueMatt

lightning-invoice/src/lib.rs

@@ -1922,7 +1922,11 @@ mod test {
 		);
 		assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
 		assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
-		assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+		let mut features = InvoiceFeatures::empty();
+		features.set_payment_secret_required();
+		features.set_variable_length_onion_required();
+		features.set_basic_mpp_optional();
+		assert_eq!(invoice.features(), Some(&features));
 
 		let raw_invoice = builder.build_raw().unwrap();
 		assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())

lightning/src/ln/features.rs

@@ -192,14 +192,33 @@ mod sealed {
 			VariableLengthOnion | PaymentSecret,
 			// Byte 2
 			,
+			// Byte 3
+			,
+			// Byte 4
+			,
+			// Byte 5
+			,
+			// Byte 6
+			,
 		],
+		// Note that the optional feature bits set here are used to check if a bit is "known", but
+		// the `InvoiceBuilder` in lightning-invoice starts with `empty()` and does not set these
+		// bits unless the relevant data is included in the invoice.
 		optional_features: [
 			// Byte 0
 			,
 			// Byte 1
 			,
 			// Byte 2
 			BasicMPP,
+			// Byte 3
+			,
+			// Byte 4
+			,
+			// Byte 5
+			,
+			// Byte 6
+			PaymentMetadata,
 		],
 	});
 	// This isn't a "real" feature context, and is only used in the channel_type field in an
@@ -402,13 +421,15 @@ mod sealed {
 	define_feature!(47, SCIDPrivacy, [InitContext, NodeContext, ChannelTypeContext],
 		"Feature flags for only forwarding with SCID aliasing. Called `option_scid_alias` in the BOLTs",
 		set_scid_privacy_optional, set_scid_privacy_required, supports_scid_privacy, requires_scid_privacy);
-
+	define_feature!(49, PaymentMetadata, [InvoiceContext],
+		"Feature flags for payment metadata in invoices.", set_payment_metadata_optional,
+		set_payment_metadata_required, supports_payment_metadata, requires_payment_metadata);
 	define_feature!(55, Keysend, [NodeContext],
 		"Feature flags for keysend payments.", set_keysend_optional, set_keysend_required,
 		supports_keysend, requires_keysend);
 
 	#[cfg(test)]
-	define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext, InvoiceContext],
+	define_feature!(123456789, UnknownFeature, [NodeContext, ChannelContext, InitContext],
 		"Feature flags for an unknown feature used in testing.", set_unknown_feature_optional,
 		set_unknown_feature_required, supports_unknown_test_feature, requires_unknown_test_feature);
 }
@@ -921,11 +942,11 @@ mod tests {
 	#[test]
 	fn convert_to_context_with_unknown_flags() {
 		// Ensure the `from` context has fewer known feature bytes than the `to` context.
-		assert!(InvoiceFeatures::known().flags.len() < NodeFeatures::known().flags.len());
-		let mut invoice_features = InvoiceFeatures::known();
-		invoice_features.set_unknown_feature_optional();
-		assert!(invoice_features.supports_unknown_bits());
-		let node_features: NodeFeatures = invoice_features.to_context();
+		assert!(InitFeatures::known().flags.len() < NodeFeatures::known().flags.len());
+		let mut init_features = InitFeatures::known();
+		init_features.set_unknown_feature_optional();
+		assert!(init_features.supports_unknown_bits());
+		let node_features: NodeFeatures = init_features.to_context();
 		assert!(!node_features.supports_unknown_bits());
 	}
 

lightning/src/routing/router.rs

@@ -4917,7 +4917,6 @@ mod tests {
 			assert_eq!(route.paths[0][1].short_channel_id, 13);
 			assert_eq!(route.paths[0][1].fee_msat, 90_000);
 			assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
-			assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
 			assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
 		}
 	}