From b362314340ecfa67a33ece4827674755f031dd32 Mon Sep 17 00:00:00 2001
From: Tom Kirkpatrick <tom@strike.me>
Date: Fri, 9 Feb 2024 15:26:16 +0000
Subject: [PATCH] Include outgoing payment description in audit memo

---
 accounting/entries.go | 19 +++++++++++++++----
 accounting/filter.go  | 41 +++++++++++++++++++++++++++++++++++------
 2 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/accounting/entries.go b/accounting/entries.go
index 3de443c..208bde2 100644
--- a/accounting/entries.go
+++ b/accounting/entries.go
@@ -401,11 +401,22 @@ func paymentReference(sequenceNumber uint64, preimage lntypes.Preimage) string {
 
 // paymentNote creates a note for payments from our node.
 // nolint: interfacer
-func paymentNote(dest *route.Vertex) string {
-	if dest == nil {
+func paymentNote(dest *route.Vertex, memo *string) string {
+	var notes []string
+
+	if memo != nil && *memo != "" {
+		notes = append(notes, fmt.Sprintf("memo: %v", *memo))
+	}
+
+	if dest != nil {
+		notes = append(notes, fmt.Sprintf("destination: %v", dest))
+	}
+
+	if len(notes) == 0 {
 		return ""
 	}
-	return dest.String()
+
+	return strings.Join(notes, "/")
 }
 
 // paymentEntry creates an entry for an off chain payment, including fee entries
@@ -432,7 +443,7 @@ func paymentEntry(payment paymentInfo, paidToSelf bool,
 
 	// Create a note for our payment. Since we have already checked that our
 	// payment is settled, we will not have a nil preimage.
-	note := paymentNote(payment.destination)
+	note := paymentNote(payment.destination, payment.description)
 	ref := paymentReference(payment.SequenceNumber, *payment.Preimage)
 
 	// Payment values are expressed as positive values over rpc, but they
diff --git a/accounting/filter.go b/accounting/filter.go
index 90f48e5..f221b01 100644
--- a/accounting/filter.go
+++ b/accounting/filter.go
@@ -109,15 +109,16 @@ func filterInvoices(startTime, endTime time.Time,
 	return filtered
 }
 
-// paymentInfo wraps a lndclient payment struct with a destination, if it is
-// available from the information we have available, and its settle time.
-// Since we now allow multi-path payments, a single payment may have multiple
-// htlcs resolved over a period of time. We use the most recent settle time for
-// payment because payments are not considered settled until all the htlcs are
-// resolved.
+// paymentInfo wraps a lndclient payment struct with a destination, and
+// description if available from the information we have available, and its
+// settle time. Since we now allow multi-path payments, a single payment may
+// have multiple htlcs resolved over a period of time. We use the most recent
+// settle time for payment because payments are not considered settled until
+// all the htlcs are resolved.
 type paymentInfo struct {
 	lndclient.Payment
 	destination *route.Vertex
+	description *string
 	settleTime  time.Time
 }
 
@@ -150,9 +151,20 @@ func preProcessPayments(payments []lndclient.Payment,
 			}
 		}
 
+		// Try to get our payment description from our payment request
+		// This value may not be present for all payments, so we do not
+		// error if it is not.
+		description, err := paymentRequestDescription(
+			payment.PaymentRequest, decode,
+		)
+		if err != nil && err != errNoPaymentRequest {
+			return nil, err
+		}
+
 		pmt := paymentInfo{
 			Payment:     payment,
 			destination: destination,
+			description: description,
 		}
 
 		// If the payment did not succeed, we can add it to our list
@@ -229,6 +241,23 @@ func paymentRequestDestination(paymentRequest string,
 	return &payReq.Destination, nil
 }
 
+// paymentRequestDescription attempts to decode a payment address, and returns
+// the description.
+func paymentRequestDescription(paymentRequest string,
+	decode decodePaymentRequest) (*string, error) {
+
+	if paymentRequest == "" {
+		return nil, errNoPaymentRequest
+	}
+
+	payReq, err := decode(paymentRequest)
+	if err != nil {
+		return nil, fmt.Errorf("decode payment request failed: %w", err)
+	}
+
+	return &payReq.Description, nil
+}
+
 // filterPayments filters out unsuccessful payments and those which did not
 // occur within the range we specify.
 func filterPayments(startTime, endTime time.Time,