Require a PaymentContext in payment::ReceiveTlvs

UnknownPaymentContext is used when payment::ReceiveTlvs doesn't contain
a PaymentContext. This is only needed for a legacy BlindedPaymentPath.
Since these paths a short-lived, UnknownPaymentContext is no longer
needed. Remove it and require that payment::ReceiveTlvs always contains
a PaymentContext.

Any such path would fail authentication since the payment::ReceiveTlvs
would be missing an HMAC and Nonce, so this is a good time to remove
UnknownPaymentContext.

Author: jkczyz

lightning/src/blinded_path/payment.rs

@@ -315,9 +315,6 @@ pub struct PaymentConstraints {
 /// [`PaymentPurpose`]: crate::events::PaymentPurpose
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub enum PaymentContext {
-	/// The payment context was unknown.
-	Unknown(UnknownPaymentContext),
-
 	/// The payment was made for an invoice requested from a BOLT 12 [`Offer`].
 	///
 	/// [`Offer`]: crate::offers::offer::Offer
@@ -335,10 +332,6 @@ pub(crate) enum PaymentContextRef<'a> {
 	Bolt12Refund(&'a Bolt12RefundContext),
 }
 
-/// An unknown payment context.
-#[derive(Clone, Debug, Eq, PartialEq)]
-pub struct UnknownPaymentContext(());
-
 /// The context of a payment made for an invoice requested from a BOLT 12 [`Offer`].
 ///
 /// [`Offer`]: crate::offers::offer::Offer
@@ -362,12 +355,6 @@ pub struct Bolt12OfferContext {
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct Bolt12RefundContext {}
 
-impl PaymentContext {
-	pub(crate) fn unknown() -> Self {
-		PaymentContext::Unknown(UnknownPaymentContext(()))
-	}
-}
-
 impl TryFrom<CounterpartyForwardingInfo> for PaymentRelay {
 	type Error = ();
 
@@ -437,7 +424,7 @@ impl Readable for BlindedPaymentTlvs {
 			(12, payment_constraints, required),
 			(14, features, (option, encoding: (BlindedHopFeatures, WithoutLength))),
 			(65536, payment_secret, option),
-			(65537, payment_context, (default_value, PaymentContext::unknown())),
+			(65537, payment_context, option),
 			(65539, authentication, option),
 		});
 		let _padding: Option<utils::Padding> = _padding;
@@ -458,7 +445,7 @@ impl Readable for BlindedPaymentTlvs {
 			Ok(BlindedPaymentTlvs::Receive(ReceiveTlvs {
 				payment_secret: payment_secret.ok_or(DecodeError::InvalidValue)?,
 				payment_constraints: payment_constraints.0.unwrap(),
-				payment_context: payment_context.0.unwrap(),
+				payment_context: payment_context.ok_or(DecodeError::InvalidValue)?,
 				authentication,
 			}))
 		}
@@ -595,7 +582,6 @@ impl Readable for PaymentConstraints {
 
 impl_writeable_tlv_based_enum_legacy!(PaymentContext,
 	;
-	(0, Unknown),
 	(1, Bolt12Offer),
 	(2, Bolt12Refund),
 );
@@ -617,18 +603,6 @@ impl<'a> Writeable for PaymentContextRef<'a> {
 	}
 }
 
-impl Writeable for UnknownPaymentContext {
-	fn write<W: Writer>(&self, _w: &mut W) -> Result<(), io::Error> {
-		Ok(())
-	}
-}
-
-impl Readable for UnknownPaymentContext {
-	fn read<R: io::Read>(_r: &mut R) -> Result<Self, DecodeError> {
-		Ok(UnknownPaymentContext(()))
-	}
-}
-
 impl_writeable_tlv_based!(Bolt12OfferContext, {
 	(0, offer_id, required),
 	(2, invoice_request, required),
@@ -639,7 +613,7 @@ impl_writeable_tlv_based!(Bolt12RefundContext, {});
 #[cfg(test)]
 mod tests {
 	use bitcoin::secp256k1::PublicKey;
-	use crate::blinded_path::payment::{PaymentForwardNode, ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentContext, PaymentRelay};
+	use crate::blinded_path::payment::{Bolt12RefundContext, PaymentForwardNode, ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentContext, PaymentRelay};
 	use crate::types::payment::PaymentSecret;
 	use crate::types::features::BlindedHopFeatures;
 	use crate::ln::functional_test_utils::TEST_FINAL_CLTV;
@@ -690,7 +664,7 @@ mod tests {
 				max_cltv_expiry: 0,
 				htlc_minimum_msat: 1,
 			},
-			payment_context: PaymentContext::unknown(),
+			payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 			authentication: None,
 		};
 		let htlc_maximum_msat = 100_000;
@@ -710,7 +684,7 @@ mod tests {
 				max_cltv_expiry: 0,
 				htlc_minimum_msat: 1,
 			},
-			payment_context: PaymentContext::unknown(),
+			payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 			authentication: None,
 		};
 		let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs, 4242, TEST_FINAL_CLTV as u16).unwrap();
@@ -767,7 +741,7 @@ mod tests {
 				max_cltv_expiry: 0,
 				htlc_minimum_msat: 3,
 			},
-			payment_context: PaymentContext::unknown(),
+			payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 			authentication: None,
 		};
 		let htlc_maximum_msat = 100_000;
@@ -821,7 +795,7 @@ mod tests {
 				max_cltv_expiry: 0,
 				htlc_minimum_msat: 1,
 			},
-			payment_context: PaymentContext::unknown(),
+			payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 			authentication: None,
 		};
 		let htlc_minimum_msat = 3798;
@@ -879,7 +853,7 @@ mod tests {
 				max_cltv_expiry: 0,
 				htlc_minimum_msat: 1,
 			},
-			payment_context: PaymentContext::unknown(),
+			payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 			authentication: None,
 		};
 

lightning/src/events/mod.rs

@@ -183,7 +183,7 @@ impl PaymentPurpose {
 		payment_context: Option<PaymentContext>,
 	) -> Self {
 		match payment_context {
-			Some(PaymentContext::Unknown(_)) | None => {
+			None => {
 				PaymentPurpose::Bolt11InvoicePayment {
 					payment_preimage,
 					payment_secret,

lightning/src/ln/blinded_payment_tests.rs

@@ -14,7 +14,7 @@ use bitcoin::secp256k1::{PublicKey, Scalar, Secp256k1, SecretKey, schnorr};
 use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
 use crate::blinded_path;
-use crate::blinded_path::payment::{BlindedPaymentPath, PaymentForwardNode, ForwardTlvs, PaymentConstraints, PaymentContext, PaymentRelay, ReceiveTlvs};
+use crate::blinded_path::payment::{BlindedPaymentPath, Bolt12RefundContext, PaymentForwardNode, ForwardTlvs, PaymentConstraints, PaymentContext, PaymentRelay, ReceiveTlvs};
 use crate::events::{Event, HTLCDestination, MessageSendEvent, MessageSendEventsProvider, PaymentFailureReason};
 use crate::ln::types::ChannelId;
 use crate::types::payment::{PaymentHash, PaymentSecret};
@@ -81,7 +81,7 @@ fn blinded_payment_path(
 			htlc_minimum_msat:
 				intro_node_min_htlc_opt.unwrap_or_else(|| channel_upds.last().unwrap().htlc_minimum_msat),
 		},
-		payment_context: PaymentContext::unknown(),
+		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 		authentication: None,
 	};
 	payee_tlvs.authentication = Some(hmac_payee_tlvs(&payee_tlvs, keys_manager));
@@ -139,7 +139,7 @@ fn do_one_hop_blinded_path(success: bool) {
 			max_cltv_expiry: u32::max_value(),
 			htlc_minimum_msat: chan_upd.htlc_minimum_msat,
 		},
-		payment_context: PaymentContext::unknown(),
+		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 		authentication: None,
 	};
 	payee_tlvs.authentication = Some(hmac_payee_tlvs(&payee_tlvs, &chanmon_cfgs[1].keys_manager));
@@ -185,7 +185,7 @@ fn mpp_to_one_hop_blinded_path() {
 			max_cltv_expiry: u32::max_value(),
 			htlc_minimum_msat: chan_upd_1_3.htlc_minimum_msat,
 		},
-		payment_context: PaymentContext::unknown(),
+		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 		authentication: None,
 	};
 	payee_tlvs.authentication = Some(hmac_payee_tlvs(&payee_tlvs, &chanmon_cfgs[3].keys_manager));
@@ -1398,7 +1398,7 @@ fn custom_tlvs_to_blinded_path() {
 			max_cltv_expiry: u32::max_value(),
 			htlc_minimum_msat: chan_upd.htlc_minimum_msat,
 		},
-		payment_context: PaymentContext::unknown(),
+		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 		authentication: None,
 	};
 	payee_tlvs.authentication = Some(hmac_payee_tlvs(&payee_tlvs, &chanmon_cfgs[1].keys_manager));

lightning/src/ln/max_payment_path_len_tests.rs

@@ -12,7 +12,7 @@
 
 use bitcoin::secp256k1::{Secp256k1, PublicKey};
 use crate::blinded_path::BlindedHop;
-use crate::blinded_path::payment::{BlindedPayInfo, BlindedPaymentPath, PaymentConstraints, PaymentContext, ReceiveTlvs};
+use crate::blinded_path::payment::{BlindedPayInfo, BlindedPaymentPath, Bolt12RefundContext, PaymentConstraints, PaymentContext, ReceiveTlvs};
 use crate::events::{Event, MessageSendEventsProvider};
 use crate::types::payment::PaymentSecret;
 use crate::ln::blinded_payment_tests::get_blinded_route_parameters;
@@ -165,7 +165,7 @@ fn one_hop_blinded_path_with_custom_tlv() {
 			max_cltv_expiry: u32::max_value(),
 			htlc_minimum_msat: chan_upd_1_2.htlc_minimum_msat,
 		},
-		payment_context: PaymentContext::unknown(),
+		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 		authentication: None,
 	};
 	let nonce = Nonce([42u8; 16]);