Async receive prefactor

fuzz/src/chanmon_consistency.rs

@@ -133,7 +133,7 @@ impl Router for FuzzRouter {
 
 	fn create_blinded_payment_paths<T: secp256k1::Signing + secp256k1::Verification>(
 		&self, _recipient: PublicKey, _first_hops: Vec<ChannelDetails>, _tlvs: ReceiveTlvs,
-		_amount_msats: u64, _secp_ctx: &Secp256k1<T>,
+		_amount_msats: Option<u64>, _secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedPaymentPath>, ()> {
 		unreachable!()
 	}

fuzz/src/full_stack.rs

@@ -160,7 +160,7 @@ impl Router for FuzzRouter {
 
 	fn create_blinded_payment_paths<T: secp256k1::Signing + secp256k1::Verification>(
 		&self, _recipient: PublicKey, _first_hops: Vec<ChannelDetails>, _tlvs: ReceiveTlvs,
-		_amount_msats: u64, _secp_ctx: &Secp256k1<T>,
+		_amount_msats: Option<u64>, _secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedPaymentPath>, ()> {
 		unreachable!()
 	}

fuzz/src/onion_message.rs

@@ -122,7 +122,8 @@ struct TestAsyncPaymentsMessageHandler {}
 
 impl AsyncPaymentsMessageHandler for TestAsyncPaymentsMessageHandler {
 	fn handle_held_htlc_available(
-		&self, _message: HeldHtlcAvailable, responder: Option<Responder>,
+		&self, _message: HeldHtlcAvailable, _context: AsyncPaymentsContext,
+		responder: Option<Responder>,
 	) -> Option<(ReleaseHeldHtlc, ResponseInstruction)> {
 		let responder = match responder {
 			Some(resp) => resp,

lightning/src/blinded_path/message.rs

@@ -402,6 +402,24 @@ pub enum AsyncPaymentsContext {
 		/// containing the expected [`PaymentId`].
 		hmac: Hmac<Sha256>,
 	},
+	/// Context contained within the [`BlindedMessagePath`]s we put in static invoices, provided back
+	/// to us in corresponding [`HeldHtlcAvailable`] messages.
+	///
+	/// [`HeldHtlcAvailable`]: crate::onion_message::async_payments::HeldHtlcAvailable
+	InboundPayment {
+		/// A nonce used for authenticating that a [`HeldHtlcAvailable`] message is valid for a
+		/// preceding static invoice.
+		///
+		/// [`HeldHtlcAvailable`]: crate::onion_message::async_payments::HeldHtlcAvailable
+		nonce: Nonce,
+		/// Authentication code for the [`HeldHtlcAvailable`] message.
+		///
+		/// Prevents nodes from creating their own blinded path to us, sending a [`HeldHtlcAvailable`]
+		/// message and trivially getting notified whenever we come online.
+		///
+		/// [`HeldHtlcAvailable`]: crate::onion_message::async_payments::HeldHtlcAvailable
+		hmac: Hmac<Sha256>,
+	},
 }
 
 impl_writeable_tlv_based_enum!(MessageContext,
@@ -433,6 +451,10 @@ impl_writeable_tlv_based_enum!(AsyncPaymentsContext,
 		(2, nonce, required),
 		(4, hmac, required),
 	},
+	(1, InboundPayment) => {
+		(0, nonce, required),
+		(2, hmac, required),
+	},
 );
 
 /// Contains a simple nonce for use in a blinded path's context.

lightning/src/blinded_path/payment.rs

@@ -349,6 +349,11 @@ pub enum PaymentContext {
 	/// [`Offer`]: crate::offers::offer::Offer
 	Bolt12Offer(Bolt12OfferContext),
 
+	/// The payment was made for a static invoice requested from a BOLT 12 [`Offer`].
+	///
+	/// [`Offer`]: crate::offers::offer::Offer
+	AsyncBolt12Offer(AsyncBolt12OfferContext),
+
 	/// The payment was made for an invoice sent for a BOLT 12 [`Refund`].
 	///
 	/// [`Refund`]: crate::offers::refund::Refund
@@ -378,6 +383,18 @@ pub struct Bolt12OfferContext {
 	pub invoice_request: InvoiceRequestFields,
 }
 
+/// The context of a payment made for a static invoice requested from a BOLT 12 [`Offer`].
+///
+/// [`Offer`]: crate::offers::offer::Offer
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct AsyncBolt12OfferContext {
+	/// The [`Nonce`] used to verify that an inbound [`InvoiceRequest`] corresponds to this static
+	/// invoice's offer.
+	///
+	/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+	pub offer_nonce: Nonce,
+}
+
 /// The context of a payment made for an invoice sent for a BOLT 12 [`Refund`].
 ///
 /// [`Refund`]: crate::offers::refund::Refund
@@ -627,6 +644,7 @@ impl_writeable_tlv_based_enum_legacy!(PaymentContext,
 	// 0 for Unknown removed in version 0.1.
 	(1, Bolt12Offer),
 	(2, Bolt12Refund),
+	(3, AsyncBolt12Offer),
 );
 
 impl<'a> Writeable for PaymentContextRef<'a> {
@@ -651,6 +669,10 @@ impl_writeable_tlv_based!(Bolt12OfferContext, {
 	(2, invoice_request, required),
 });
 
+impl_writeable_tlv_based!(AsyncBolt12OfferContext, {
+	(0, offer_nonce, required),
+});
+
 impl_writeable_tlv_based!(Bolt12RefundContext, {});
 
 #[cfg(test)]

lightning/src/events/mod.rs

@@ -181,27 +181,32 @@ impl PaymentPurpose {
 	pub(crate) fn from_parts(
 		payment_preimage: Option<PaymentPreimage>, payment_secret: PaymentSecret,
 		payment_context: Option<PaymentContext>,
-	) -> Self {
+	) -> Result<Self, ()> {
 		match payment_context {
 			None => {
-				PaymentPurpose::Bolt11InvoicePayment {
+				Ok(PaymentPurpose::Bolt11InvoicePayment {
 					payment_preimage,
 					payment_secret,
-				}
+				})
 			},
 			Some(PaymentContext::Bolt12Offer(context)) => {
-				PaymentPurpose::Bolt12OfferPayment {
+				Ok(PaymentPurpose::Bolt12OfferPayment {
 					payment_preimage,
 					payment_secret,
 					payment_context: context,
-				}
+				})
 			},
 			Some(PaymentContext::Bolt12Refund(context)) => {
-				PaymentPurpose::Bolt12RefundPayment {
+				Ok(PaymentPurpose::Bolt12RefundPayment {
 					payment_preimage,
 					payment_secret,
 					payment_context: context,
-				}
+				})
+			},
+			Some(PaymentContext::AsyncBolt12Offer(_context)) => {
+				// This code will change to return Self::Bolt12OfferPayment when we add support for async
+				// receive.
+				Err(())
 			},
 		}
 	}
@@ -1865,7 +1870,8 @@ impl MaybeReadable for Event {
 						(13, payment_id, option),
 					});
 					let purpose = match payment_secret {
-						Some(secret) => PaymentPurpose::from_parts(payment_preimage, secret, payment_context),
+						Some(secret) => PaymentPurpose::from_parts(payment_preimage, secret, payment_context)
+							.map_err(|()| msgs::DecodeError::InvalidValue)?,
 						None if payment_preimage.is_some() => PaymentPurpose::SpontaneousPayment(payment_preimage.unwrap()),
 						None => return Err(msgs::DecodeError::InvalidValue),
 					};