accounts: associate payments before sending them

Author: ViktorT-11

accounts/checkers.go

@@ -522,6 +522,7 @@ func checkSend(ctx context.Context, chainParams *chaincfg.Params,
 	}
 
 	// The invoice is optional.
+	var paymentHash lntypes.Hash
 	if len(invoice) > 0 {
 		payReq, err := zpay32.Decode(invoice, chainParams)
 		if err != nil {
@@ -531,6 +532,10 @@ func checkSend(ctx context.Context, chainParams *chaincfg.Params,
 		if payReq.MilliSat != nil && *payReq.MilliSat > sendAmt {
 			sendAmt = *payReq.MilliSat
 		}
+
+		if payReq.PaymentHash != nil {
+			paymentHash = *payReq.PaymentHash
+		}
 	}
 
 	// We also add the max fee to the amount to check. This might mean that
@@ -549,6 +554,14 @@ func checkSend(ctx context.Context, chainParams *chaincfg.Params,
 		return fmt.Errorf("error validating account balance: %w", err)
 	}
 
+	emptyHash := lntypes.Hash{}
+	if paymentHash != emptyHash {
+		err = service.AssociatePayment(acct.ID, paymentHash, sendAmt)
+		if err != nil {
+			return fmt.Errorf("error associating payment: %w", err)
+		}
+	}
+
 	return nil
 }
 

accounts/checkers_test.go

@@ -68,6 +68,12 @@ func (m *mockService) AssociateInvoice(id AccountID, hash lntypes.Hash) error {
 	return nil
 }
 
+func (m *mockService) AssociatePayment(id AccountID, paymentHash lntypes.Hash,
+	amt lnwire.MilliSatoshi) error {
+
+	return nil
+}
+
 func (m *mockService) TrackPayment(_ AccountID, hash lntypes.Hash,
 	amt lnwire.MilliSatoshi) error {
 

accounts/interface.go

@@ -247,6 +247,9 @@ type Service interface {
 	// so we never need to debit the amount from the account.
 	RemovePayment(hash lntypes.Hash) error
 
-	// IsRunning returns true if the service can be used.
-	IsRunning() bool
+	// AssociatePayment associates a payment (hash) with the given account,
+	// ensuring that the payment will be tracked for a user when LiT is
+	// restarted.
+	AssociatePayment(id AccountID, paymentHash lntypes.Hash,
+		fullAmt lnwire.MilliSatoshi) error
 }

accounts/service.go

@@ -416,6 +416,40 @@ func (s *InterceptorService) AssociateInvoice(id AccountID,
 	return s.store.UpdateAccount(account)
 }
 
+// AssociatePayment associates a payment (hash) with the given account,
+// ensuring that the payment will be tracked for a user when LiT is
+// restarted.
+func (s *InterceptorService) AssociatePayment(id AccountID,
+	paymentHash lntypes.Hash, fullAmt lnwire.MilliSatoshi) error {
+
+	s.Lock()
+	defer s.Unlock()
+
+	account, err := s.store.Account(id)
+	if err != nil {
+		return err
+	}
+
+	// If the payment is already associated with the account, we don't need
+	// to associate it again.
+	_, ok := account.Payments[paymentHash]
+	if ok {
+		return nil
+	}
+
+	// Associate the payment with the account and store it.
+	account.Payments[paymentHash] = &PaymentEntry{
+		Status:     lnrpc.Payment_UNKNOWN,
+		FullAmount: fullAmt,
+	}
+
+	if err := s.store.UpdateAccount(account); err != nil {
+		return fmt.Errorf("error updating account: %w", err)
+	}
+
+	return nil
+}
+
 // invoiceUpdate credits the account an invoice was registered with, in case the
 // invoice was settled.
 //
@@ -527,13 +561,33 @@ func (s *InterceptorService) TrackPayment(id AccountID, hash lntypes.Hash,
 		return nil
 	}
 
-	// Okay, we haven't tracked this payment before. So let's now associate
-	// the account with it.
 	account.Payments[hash] = &PaymentEntry{
 		Status:     lnrpc.Payment_UNKNOWN,
 		FullAmount: fullAmt,
 	}
+
 	if err := s.store.UpdateAccount(account); err != nil {
+		if !ok {
+			// In the rare case that the payment isn't associated
+			// with an account yet, and we fail to update the
+			// account we will not be tracking the payment, even if
+			// track the service is restarted. Therefore the node
+			// runner needs to manually check if the payment was
+			// made and debit the account if that's the case.
+			errStr := "critical error: failed to store the " +
+				"payment with hash %v for user with account " +
+				"id %v. Manual intervention required! " +
+				"Verify if the payment was executed, and " +
+				"manually update the user account balance by " +
+				"subtracting the payment amount if it was"
+
+			mainChanErr := s.disableAndErrorfUnsafe(
+				errStr, hash, id,
+			)
+
+			s.mainErrCallback(mainChanErr)
+		}
+
 		return fmt.Errorf("error updating account: %w", err)
 	}