WIP: Authenticate invoices

Author: jkczyz

lightning/src/ln/channelmanager.rs

@@ -10366,8 +10366,17 @@ where
 				}
 			},
 			OffersMessage::Invoice(invoice) => {
+				let expected_payment_id = match context {
+					OffersContext::OutboundPayment { payment_id } => payment_id,
+					_ => return ResponseInstruction::NoResponse,
+				};
+
 				let result = match invoice.verify(expanded_key, secp_ctx) {
 					Ok(payment_id) => {
+						if payment_id != expected_payment_id {
+							return ResponseInstruction::NoResponse;
+						}
+
 						let features = self.bolt12_invoice_features();
 						if invoice.invoice_features().requires_unknown_bits_from(&features) {
 							Err(InvoiceError::from(Bolt12SemanticError::UnknownRequiredFeatures))