Attributable failures optional feature bit

Signal to senders that the node will return attributable failures. When
the sender makes sure all path nodes supports this, they will be able to
attribute every failure that may occur.

Author: joostjager

lightning-invoice/src/lib.rs

@@ -597,12 +597,18 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::F
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currency: Currency) -> Self {
+		let mut features = Bolt11InvoiceFeatures::empty();
+		features.set_attributable_failures_optional();
+
+		let mut tagged_fields = Vec::with_capacity(8);
+		tagged_fields.push(TaggedField::Features(features));
+
 		InvoiceBuilder {
 			currency,
 			amount: None,
 			si_prefix: None,
 			timestamp: None,
-			tagged_fields: Vec::with_capacity(8),
+			tagged_fields,
 			error: None,
 
 			phantom_d: core::marker::PhantomData,

lightning-types/src/features.rs

@@ -154,7 +154,7 @@ mod sealed {
 			// Byte 3
 			RouteBlinding | ShutdownAnySegwit | DualFund | Taproot,
 			// Byte 4
-			Quiescence | OnionMessages,
+			Quiescence | OnionMessages | AttributableFailures,
 			// Byte 5
 			ProvideStorage | ChannelType | SCIDPrivacy,
 			// Byte 6
@@ -175,7 +175,7 @@ mod sealed {
 			// Byte 3
 			RouteBlinding | ShutdownAnySegwit | DualFund | Taproot,
 			// Byte 4
-			Quiescence | OnionMessages,
+			Quiescence | OnionMessages | AttributableFailures,
 			// Byte 5
 			ProvideStorage | ChannelType | SCIDPrivacy,
 			// Byte 6
@@ -199,7 +199,7 @@ mod sealed {
 		// Byte 3
 		,
 		// Byte 4
-		,
+		AttributableFailures,
 		// Byte 5
 		,
 		// Byte 6
@@ -219,7 +219,7 @@ mod sealed {
 		// Byte 3
 		,
 		// Byte 4
-		,
+		AttributableFailures,
 		// Byte 5
 		,
 		// Byte 6
@@ -548,6 +548,16 @@ mod sealed {
 		supports_quiescence,
 		requires_quiescence
 	);
+	define_feature!(
+		37,
+		AttributableFailures,
+		[InitContext, NodeContext, Bolt11InvoiceContext, Bolt12InvoiceContext],
+		"Feature flags for `option_attributable_failures`.",
+		set_attributable_failures_optional,
+		set_attributable_failures_required,
+		supports_attributable_failures,
+		requires_attributable_failures
+	);
 	define_feature!(
 		39,
 		OnionMessages,

lightning/src/offers/invoice.rs

@@ -413,14 +413,17 @@ macro_rules! invoice_builder_methods {
 			payment_paths: Vec<BlindedPaymentPath>, created_at: Duration,
 			payment_hash: PaymentHash, amount_msats: u64, signing_pubkey: PublicKey,
 		) -> InvoiceFields {
+			let mut features = Bolt12InvoiceFeatures::empty();
+			features.set_attributable_failures_optional();
+
 			InvoiceFields {
 				payment_paths,
 				created_at,
 				relative_expiry: None,
 				payment_hash,
 				amount_msats,
 				fallbacks: None,
-				features: Bolt12InvoiceFeatures::empty(),
+				features,
 				signing_pubkey,
 				#[cfg(test)]
 				experimental_baz: None,
@@ -1777,6 +1780,7 @@ mod tests {
 	use bitcoin::secp256k1::{self, Keypair, Message, Secp256k1, SecretKey, XOnlyPublicKey};
 	use bitcoin::{CompressedPublicKey, WitnessProgram, WitnessVersion};
 
+	use core::f32::consts::E;
 	use core::time::Duration;
 
 	use crate::blinded_path::message::BlindedMessagePath;
@@ -1878,7 +1882,10 @@ mod tests {
 		assert!(!unsigned_invoice.is_expired());
 		assert_eq!(unsigned_invoice.payment_hash(), payment_hash);
 		assert!(unsigned_invoice.fallbacks().is_empty());
-		assert_eq!(unsigned_invoice.invoice_features(), &Bolt12InvoiceFeatures::empty());
+
+		let mut expected_features = Bolt12InvoiceFeatures::empty();
+		expected_features.set_attributable_failures_optional();
+		assert_eq!(unsigned_invoice.invoice_features(), &expected_features);
 
 		match UnsignedBolt12Invoice::try_from(buffer) {
 			Err(e) => panic!("error parsing unsigned invoice: {:?}", e),
@@ -1926,7 +1933,7 @@ mod tests {
 		assert!(!invoice.is_expired());
 		assert_eq!(invoice.payment_hash(), payment_hash);
 		assert!(invoice.fallbacks().is_empty());
-		assert_eq!(invoice.invoice_features(), &Bolt12InvoiceFeatures::empty());
+		assert_eq!(invoice.invoice_features(), &expected_features);
 		assert!(!invoice.is_for_refund_without_paths());
 
 		let message = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &invoice.bytes);
@@ -1974,7 +1981,7 @@ mod tests {
 					payment_hash: Some(&payment_hash),
 					amount: Some(1000),
 					fallbacks: None,
-					features: None,
+					features: Some(&expected_features),
 					node_id: Some(&recipient_pubkey()),
 					message_paths: None,
 				},
@@ -2009,6 +2016,9 @@ mod tests {
 		let mut buffer = Vec::new();
 		invoice.write(&mut buffer).unwrap();
 
+		let mut expected_features = Bolt12InvoiceFeatures::empty();
+		expected_features.set_attributable_failures_optional();
+
 		assert_eq!(invoice.bytes, buffer.as_slice());
 		assert_eq!(invoice.payer_metadata(), &[1; 32]);
 		assert_eq!(invoice.offer_chains(), None);
@@ -2034,7 +2044,7 @@ mod tests {
 		assert!(!invoice.is_expired());
 		assert_eq!(invoice.payment_hash(), payment_hash);
 		assert!(invoice.fallbacks().is_empty());
-		assert_eq!(invoice.invoice_features(), &Bolt12InvoiceFeatures::empty());
+		assert_eq!(invoice.invoice_features(), &expected_features);
 		assert!(invoice.is_for_refund_without_paths());
 
 		let message = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &invoice.bytes);
@@ -2077,7 +2087,7 @@ mod tests {
 					payment_hash: Some(&payment_hash),
 					amount: Some(1000),
 					fallbacks: None,
-					features: None,
+					features: Some(&expected_features),
 					node_id: Some(&recipient_pubkey()),
 					message_paths: None,
 				},
@@ -2501,6 +2511,7 @@ mod tests {
 
 		let mut features = Bolt12InvoiceFeatures::empty();
 		features.set_basic_mpp_optional();
+		features.set_attributable_failures_optional();
 
 		let invoice = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
@@ -2838,6 +2849,7 @@ mod tests {
 			Ok(invoice) => {
 				let mut features = Bolt12InvoiceFeatures::empty();
 				features.set_basic_mpp_optional();
+				features.set_attributable_failures_optional();
 				assert_eq!(invoice.invoice_features(), &features);
 			},
 			Err(e) => panic!("error parsing invoice: {:?}", e),