routing: return full htlc attempt from shard handler

channeldb/mp_payment.go

@@ -2,6 +2,7 @@ package channeldb
 
 import (
 	"bytes"
+	"errors"
 	"io"
 	"time"
 
@@ -177,6 +178,18 @@ func (m *MPPayment) InFlightHTLCs() []HTLCAttempt {
 	return inflights
 }
 
+// GetAttempt returns the specified htlc attempt on the payment.
+func (m *MPPayment) GetAttempt(id uint64) (*HTLCAttempt, error) {
+	for _, htlc := range m.HTLCs {
+		htlc := htlc
+		if htlc.AttemptID == id {
+			return &htlc, nil
+		}
+	}
+
+	return nil, errors.New("htlc attempt not found on payment")
+}
+
 // serializeHTLCSettleInfo serializes the details of a settled htlc.
 func serializeHTLCSettleInfo(w io.Writer, s *HTLCSettleInfo) error {
 	if _, err := w.Write(s.Preimage[:]); err != nil {

routing/control_tower.go

@@ -30,10 +30,12 @@ type ControlTower interface {
 	// error to prevent us from making duplicate payments to the same
 	// payment hash. The provided preimage is atomically saved to the DB
 	// for record keeping.
-	SettleAttempt(lntypes.Hash, uint64, *channeldb.HTLCSettleInfo) error
+	SettleAttempt(lntypes.Hash, uint64, *channeldb.HTLCSettleInfo) (
+		*channeldb.HTLCAttempt, error)
 
 	// FailAttempt marks the given payment attempt failed.
-	FailAttempt(lntypes.Hash, uint64, *channeldb.HTLCFailInfo) error
+	FailAttempt(lntypes.Hash, uint64, *channeldb.HTLCFailInfo) (
+		*channeldb.HTLCAttempt, error)
 
 	// FetchPayment fetches the payment corresponding to the given payment
 	// hash.
@@ -146,38 +148,40 @@ func (p *controlTower) RegisterAttempt(paymentHash lntypes.Hash,
 // this is a multi shard payment, this might implicitly mean the the
 // full payment succeeded.
 func (p *controlTower) SettleAttempt(paymentHash lntypes.Hash,
-	attemptID uint64, settleInfo *channeldb.HTLCSettleInfo) error {
+	attemptID uint64, settleInfo *channeldb.HTLCSettleInfo) (
+	*channeldb.HTLCAttempt, error) {
 
 	p.paymentsMtx.Lock(paymentHash)
 	defer p.paymentsMtx.Unlock(paymentHash)
 
 	payment, err := p.db.SettleAttempt(paymentHash, attemptID, settleInfo)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	// Notify subscribers of success event.
 	p.notifySubscribers(paymentHash, payment)
 
-	return nil
+	return payment.GetAttempt(attemptID)
 }
 
 // FailAttempt marks the given payment attempt failed.
 func (p *controlTower) FailAttempt(paymentHash lntypes.Hash,
-	attemptID uint64, failInfo *channeldb.HTLCFailInfo) error {
+	attemptID uint64, failInfo *channeldb.HTLCFailInfo) (
+	*channeldb.HTLCAttempt, error) {
 
 	p.paymentsMtx.Lock(paymentHash)
 	defer p.paymentsMtx.Unlock(paymentHash)
 
 	payment, err := p.db.FailAttempt(paymentHash, attemptID, failInfo)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	// Notify subscribers of failed attempt.
 	p.notifySubscribers(paymentHash, payment)
 
-	return nil
+	return payment.GetAttempt(attemptID)
 }
 
 // FetchPayment fetches the payment corresponding to the given payment hash.

routing/control_tower_test.go

@@ -104,15 +104,18 @@ func TestControlTowerSubscribeSuccess(t *testing.T) {
 	}
 
 	// Mark the payment as successful.
-	err = pControl.SettleAttempt(
-		info.PaymentHash, attempt.AttemptID,
-		&channeldb.HTLCSettleInfo{
-			Preimage: preimg,
-		},
+	settleInfo := channeldb.HTLCSettleInfo{
+		Preimage: preimg,
+	}
+	htlcAttempt, err := pControl.SettleAttempt(
+		info.PaymentHash, attempt.AttemptID, &settleInfo,
 	)
 	if err != nil {
 		t.Fatal(err)
 	}
+	if *htlcAttempt.Settle != settleInfo {
+		t.Fatalf("unexpected settle info returned")
+	}
 
 	// Register a third subscriber after the payment succeeded.
 	subscriber3, err := pControl.SubscribePayment(info.PaymentHash)
@@ -215,13 +218,18 @@ func testPaymentControlSubscribeFail(t *testing.T, registerAttempt bool) {
 		}
 
 		// Fail the payment attempt.
-		err := pControl.FailAttempt(
-			info.PaymentHash, attempt.AttemptID,
-			&channeldb.HTLCFailInfo{},
+		failInfo := channeldb.HTLCFailInfo{
+			Reason: channeldb.HTLCFailInternal,
+		}
+		htlcAttempt, err := pControl.FailAttempt(
+			info.PaymentHash, attempt.AttemptID, &failInfo,
 		)
 		if err != nil {
 			t.Fatalf("unable to fail htlc: %v", err)
 		}
+		if *htlcAttempt.Failure != failInfo {
+			t.Fatalf("unexpected fail info returned")
+		}
 	}
 
 	// Mark the payment as failed.

routing/mock_test.go

@@ -301,7 +301,8 @@ func (m *mockControlTower) RegisterAttempt(phash lntypes.Hash,
 }
 
 func (m *mockControlTower) SettleAttempt(phash lntypes.Hash,
-	pid uint64, settleInfo *channeldb.HTLCSettleInfo) error {
+	pid uint64, settleInfo *channeldb.HTLCSettleInfo) (
+	*channeldb.HTLCAttempt, error) {
 
 	m.Lock()
 	defer m.Unlock()
@@ -313,7 +314,7 @@ func (m *mockControlTower) SettleAttempt(phash lntypes.Hash,
 	// Only allow setting attempts if the payment is known.
 	p, ok := m.payments[phash]
 	if !ok {
-		return channeldb.ErrPaymentNotInitiated
+		return nil, channeldb.ErrPaymentNotInitiated
 	}
 
 	// Find the attempt with this pid, and set the settle info.
@@ -323,24 +324,26 @@ func (m *mockControlTower) SettleAttempt(phash lntypes.Hash,
 		}
 
 		if a.Settle != nil {
-			return channeldb.ErrAttemptAlreadySettled
+			return nil, channeldb.ErrAttemptAlreadySettled
 		}
 		if a.Failure != nil {
-			return channeldb.ErrAttemptAlreadyFailed
+			return nil, channeldb.ErrAttemptAlreadyFailed
 		}
 
 		p.attempts[i].Settle = settleInfo
 
 		// Mark the payment successful on first settled attempt.
 		m.successful[phash] = struct{}{}
-		return nil
+		return &channeldb.HTLCAttempt{
+			Settle: settleInfo,
+		}, nil
 	}
 
-	return fmt.Errorf("pid not found")
+	return nil, fmt.Errorf("pid not found")
 }
 
 func (m *mockControlTower) FailAttempt(phash lntypes.Hash, pid uint64,
-	failInfo *channeldb.HTLCFailInfo) error {
+	failInfo *channeldb.HTLCFailInfo) (*channeldb.HTLCAttempt, error) {
 
 	m.Lock()
 	defer m.Unlock()
@@ -352,7 +355,7 @@ func (m *mockControlTower) FailAttempt(phash lntypes.Hash, pid uint64,
 	// Only allow failing attempts if the payment is known.
 	p, ok := m.payments[phash]
 	if !ok {
-		return channeldb.ErrPaymentNotInitiated
+		return nil, channeldb.ErrPaymentNotInitiated
 	}
 
 	// Find the attempt with this pid, and set the failure info.
@@ -362,17 +365,19 @@ func (m *mockControlTower) FailAttempt(phash lntypes.Hash, pid uint64,
 		}
 
 		if a.Settle != nil {
-			return channeldb.ErrAttemptAlreadySettled
+			return nil, channeldb.ErrAttemptAlreadySettled
 		}
 		if a.Failure != nil {
-			return channeldb.ErrAttemptAlreadyFailed
+			return nil, channeldb.ErrAttemptAlreadyFailed
 		}
 
 		p.attempts[i].Failure = failInfo
-		return nil
+		return &channeldb.HTLCAttempt{
+			Failure: failInfo,
+		}, nil
 	}
 
-	return fmt.Errorf("pid not found")
+	return nil, fmt.Errorf("pid not found")
 }
 
 func (m *mockControlTower) Fail(phash lntypes.Hash,

routing/payment_lifecycle.go

@@ -345,6 +345,9 @@ type launchOutcome struct {
 	// reflect this error. This can be errors like not enough local
 	// balance for the given route etc.
 	err error
+
+	// attempt is the attempt structure as recorded in the database.
+	attempt *channeldb.HTLCAttempt
 }
 
 // launchShard creates and sends an HTLC attempt along the given route,
@@ -382,14 +385,15 @@ func (p *shardHandler) launchShard(rt *route.Route) (*channeldb.HTLCAttemptInfo,
 	if sendErr != nil {
 		// TODO(joostjager): Distinguish unexpected internal errors
 		// from real send errors.
-		err := p.failAttempt(attempt, sendErr)
+		htlcAttempt, err := p.failAttempt(attempt, sendErr)
 		if err != nil {
 			return nil, nil, err
 		}
 
 		// Return a launchOutcome indicating the shard failed.
 		return attempt, &launchOutcome{
-			err: sendErr,
+			attempt: htlcAttempt,
+			err:     sendErr,
 		}, nil
 	}
 
@@ -398,9 +402,8 @@ func (p *shardHandler) launchShard(rt *route.Route) (*channeldb.HTLCAttemptInfo,
 
 // shardResult holds the resulting outcome of a shard sent.
 type shardResult struct {
-	// preimage is the payment preimage in case of a settled HTLC. Only set
-	// if err is non-nil.
-	preimage lntypes.Preimage
+	// attempt is the attempt structure as recorded in the database.
+	attempt *channeldb.HTLCAttempt
 
 	// err indicates that the shard failed.
 	err error
@@ -493,13 +496,14 @@ func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (
 			"the Switch, retrying.", attempt.AttemptID,
 			p.paymentHash)
 
-		cErr := p.failAttempt(attempt, err)
+		attempt, cErr := p.failAttempt(attempt, err)
 		if cErr != nil {
 			return nil, cErr
 		}
 
 		return &shardResult{
-			err: err,
+			attempt: attempt,
+			err:     err,
 		}, nil
 
 	// A critical, unexpected error was encountered.
@@ -533,13 +537,14 @@ func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (
 	// In case of a payment failure, fail the attempt with the control
 	// tower and return.
 	if result.Error != nil {
-		err := p.failAttempt(attempt, result.Error)
+		attempt, err := p.failAttempt(attempt, result.Error)
 		if err != nil {
 			return nil, err
 		}
 
 		return &shardResult{
-			err: result.Error,
+			attempt: attempt,
+			err:     result.Error,
 		}, nil
 	}
 
@@ -558,7 +563,7 @@ func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (
 
 	// In case of success we atomically store settle result to the DB move
 	// the shard to the settled state.
-	err = p.router.cfg.Control.SettleAttempt(
+	htlcAttempt, err := p.router.cfg.Control.SettleAttempt(
 		p.paymentHash, attempt.AttemptID,
 		&channeldb.HTLCSettleInfo{
 			Preimage:   result.Preimage,
@@ -571,7 +576,7 @@ func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (
 	}
 
 	return &shardResult{
-		preimage: result.Preimage,
+		attempt: htlcAttempt,
 	}, nil
 }
 
@@ -691,7 +696,7 @@ func (p *shardHandler) handleSendError(attempt *channeldb.HTLCAttemptInfo,
 
 // failAttempt calls control tower to fail the current payment attempt.
 func (p *shardHandler) failAttempt(attempt *channeldb.HTLCAttemptInfo,
-	sendError error) error {
+	sendError error) (*channeldb.HTLCAttempt, error) {
 
 	log.Warnf("Attempt %v for payment %v failed: %v", attempt.AttemptID,
 		p.paymentHash, sendError)

routing/router.go

@@ -1827,7 +1827,7 @@ func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
 
 		// We got a successful result.
 		if result.err == nil {
-			return result.preimage, nil
+			return result.attempt.Settle.Preimage, nil
 		}
 
 		// The shard failed, break switch to handle it.