routing: use Identifier in place of PaymentHash

Since we want to support AMP payment using a different unique payment identifier (AMP payments don't go to one specific hash), we change the nomenclature to be Identifier instead of PaymentHash.
2025-12-18 14:44:22 +01:00 · 2021-03-31 12:23:08 +02:00
parent 6104d12cf8
commit f07c9d002c
17 changed files with 296 additions and 245 deletions
--- a/routing/control_tower_test.go
+++ b/routing/control_tower_test.go
@@ -79,26 +79,26 @@ func TestControlTowerSubscribeSuccess(t *testing.T) {
 		t.Fatal(err)
 	}

-	err = pControl.InitPayment(info.PaymentHash, info)
+	err = pControl.InitPayment(info.PaymentIdentifier, info)
 	if err != nil {
 		t.Fatal(err)
 	}

 	// Subscription should succeed and immediately report the InFlight
 	// status.
-	subscriber1, err := pControl.SubscribePayment(info.PaymentHash)
+	subscriber1, err := pControl.SubscribePayment(info.PaymentIdentifier)
 	if err != nil {
 		t.Fatalf("expected subscribe to succeed, but got: %v", err)
 	}

 	// Register an attempt.
-	err = pControl.RegisterAttempt(info.PaymentHash, attempt)
+	err = pControl.RegisterAttempt(info.PaymentIdentifier, attempt)
 	if err != nil {
 		t.Fatal(err)
 	}

 	// Register a second subscriber after the first attempt has started.
-	subscriber2, err := pControl.SubscribePayment(info.PaymentHash)
+	subscriber2, err := pControl.SubscribePayment(info.PaymentIdentifier)
 	if err != nil {
 		t.Fatalf("expected subscribe to succeed, but got: %v", err)
 	}
@@ -108,7 +108,7 @@ func TestControlTowerSubscribeSuccess(t *testing.T) {
 		Preimage: preimg,
 	}
 	htlcAttempt, err := pControl.SettleAttempt(
-		info.PaymentHash, attempt.AttemptID, &settleInfo,
+		info.PaymentIdentifier, attempt.AttemptID, &settleInfo,
 	)
 	if err != nil {
 		t.Fatal(err)
@@ -118,7 +118,7 @@ func TestControlTowerSubscribeSuccess(t *testing.T) {
 	}

 	// Register a third subscriber after the payment succeeded.
-	subscriber3, err := pControl.SubscribePayment(info.PaymentHash)
+	subscriber3, err := pControl.SubscribePayment(info.PaymentIdentifier)
 	if err != nil {
 		t.Fatalf("expected subscribe to succeed, but got: %v", err)
 	}
@@ -196,13 +196,13 @@ func testPaymentControlSubscribeFail(t *testing.T, registerAttempt bool) {
 		t.Fatal(err)
 	}

-	err = pControl.InitPayment(info.PaymentHash, info)
+	err = pControl.InitPayment(info.PaymentIdentifier, info)
 	if err != nil {
 		t.Fatal(err)
 	}

 	// Subscription should succeed.
-	subscriber1, err := pControl.SubscribePayment(info.PaymentHash)
+	subscriber1, err := pControl.SubscribePayment(info.PaymentIdentifier)
 	if err != nil {
 		t.Fatalf("expected subscribe to succeed, but got: %v", err)
 	}
@@ -212,7 +212,7 @@ func testPaymentControlSubscribeFail(t *testing.T, registerAttempt bool) {
 	// making any attempts at all.
 	if registerAttempt {
 		// Register an attempt.
-		err = pControl.RegisterAttempt(info.PaymentHash, attempt)
+		err = pControl.RegisterAttempt(info.PaymentIdentifier, attempt)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -222,7 +222,7 @@ func testPaymentControlSubscribeFail(t *testing.T, registerAttempt bool) {
 			Reason: channeldb.HTLCFailInternal,
 		}
 		htlcAttempt, err := pControl.FailAttempt(
-			info.PaymentHash, attempt.AttemptID, &failInfo,
+			info.PaymentIdentifier, attempt.AttemptID, &failInfo,
 		)
 		if err != nil {
 			t.Fatalf("unable to fail htlc: %v", err)
@@ -233,12 +233,12 @@ func testPaymentControlSubscribeFail(t *testing.T, registerAttempt bool) {
 	}

 	// Mark the payment as failed.
-	if err := pControl.Fail(info.PaymentHash, channeldb.FailureReasonTimeout); err != nil {
+	if err := pControl.Fail(info.PaymentIdentifier, channeldb.FailureReasonTimeout); err != nil {
 		t.Fatal(err)
 	}

 	// Register a second subscriber after the payment failed.
-	subscriber2, err := pControl.SubscribePayment(info.PaymentHash)
+	subscriber2, err := pControl.SubscribePayment(info.PaymentIdentifier)
 	if err != nil {
 		t.Fatalf("expected subscribe to succeed, but got: %v", err)
 	}
@@ -326,10 +326,10 @@ func genInfo() (*channeldb.PaymentCreationInfo, *channeldb.HTLCAttemptInfo,

 	rhash := sha256.Sum256(preimage[:])
 	return &channeldb.PaymentCreationInfo{
-			PaymentHash:    rhash,
-			Value:          testRoute.ReceiverAmt(),
-			CreationTime:   time.Unix(time.Now().Unix(), 0),
-			PaymentRequest: []byte("hola"),
+			PaymentIdentifier: rhash,
+			Value:             testRoute.ReceiverAmt(),
+			CreationTime:      time.Unix(time.Now().Unix(), 0),
+			PaymentRequest:    []byte("hola"),
 		},
 		&channeldb.HTLCAttemptInfo{
 			AttemptID:  1,
--- a/routing/integrated_routing_context_test.go
+++ b/routing/integrated_routing_context_test.go
@@ -152,6 +152,11 @@ func (c *integratedRoutingContext) testPayment(maxParts uint32,
 		MaxParts:       maxParts,
 	}

+	var paymentHash [32]byte
+	if err := payment.SetPaymentHash(paymentHash); err != nil {
+		return nil, err
+	}
+
 	if c.maxShardAmt != nil {
 		payment.MaxShardAmt = c.maxShardAmt
 	}
--- a/routing/payment_lifecycle.go
+++ b/routing/payment_lifecycle.go
@@ -24,7 +24,7 @@ type paymentLifecycle struct {
 	router        *ChannelRouter
 	totalAmount   lnwire.MilliSatoshi
 	feeLimit      lnwire.MilliSatoshi
-	paymentHash   lntypes.Hash
+	identifier    lntypes.Hash
 	paySession    PaymentSession
 	shardTracker  shards.ShardTracker
 	timeoutChan   <-chan time.Time
@@ -86,7 +86,7 @@ func (p *paymentLifecycle) paymentState(payment *channeldb.MPPayment) (
 func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 	shardHandler := &shardHandler{
 		router:       p.router,
-		paymentHash:  p.paymentHash,
+		identifier:   p.identifier,
 		shardTracker: p.shardTracker,
 		shardErrors:  make(chan error),
 		quit:         make(chan struct{}),
@@ -101,7 +101,7 @@ func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 	// up goroutines that'll collect their results and deliver them to the
 	// lifecycle loop below.
 	payment, err := p.router.cfg.Control.FetchPayment(
-		p.paymentHash,
+		p.identifier,
 	)
 	if err != nil {
 		return [32]byte{}, nil, err
@@ -110,8 +110,8 @@ func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
 	for _, a := range payment.InFlightHTLCs() {
 		a := a

-		log.Infof("Resuming payment shard %v for hash %v",
-			a.AttemptID, p.paymentHash)
+		log.Infof("Resuming payment shard %v for payment %v",
+			a.AttemptID, p.identifier)

 		shardHandler.collectResultAsync(&a.HTLCAttemptInfo)
 	}
@@ -131,7 +131,7 @@ lifecycle:
 		// act on the latest available information, whether we are
 		// resuming an existing payment or just sent a new attempt.
 		payment, err := p.router.cfg.Control.FetchPayment(
-			p.paymentHash,
+			p.identifier,
 		)
 		if err != nil {
 			return [32]byte{}, nil, err
@@ -146,7 +146,7 @@ lifecycle:

 		log.Debugf("Payment %v in state terminate=%v, "+
 			"active_shards=%v, rem_value=%v, fee_limit=%v",
-			p.paymentHash, state.terminate, state.numShardsInFlight,
+			p.identifier, state.terminate, state.numShardsInFlight,
 			state.remainingAmt, state.remainingFees)

 		switch {
@@ -193,7 +193,7 @@ lifecycle:
 			// return with an error the moment all active shards
 			// have finished.
 			saveErr := p.router.cfg.Control.Fail(
-				p.paymentHash, channeldb.FailureReasonTimeout,
+				p.identifier, channeldb.FailureReasonTimeout,
 			)
 			if saveErr != nil {
 				return [32]byte{}, nil, saveErr
@@ -215,7 +215,7 @@ lifecycle:
 		)
 		if err != nil {
 			log.Warnf("Failed to find route for payment %v: %v",
-				p.paymentHash, err)
+				p.identifier, err)

 			routeErr, ok := err.(noRouteError)
 			if !ok {
@@ -229,10 +229,10 @@ lifecycle:
 				failureCode := routeErr.FailureReason()
 				log.Debugf("Marking payment %v permanently "+
 					"failed with no route: %v",
-					p.paymentHash, failureCode)
+					p.identifier, failureCode)

 				saveErr := p.router.cfg.Control.Fail(
-					p.paymentHash, failureCode,
+					p.identifier, failureCode,
 				)
 				if saveErr != nil {
 					return [32]byte{}, nil, saveErr
@@ -261,8 +261,8 @@ lifecycle:
 		// were pathfinding. We know we're in a terminal state here,
 		// so we can continue and wait for our last shards to return.
 		case err == channeldb.ErrPaymentTerminal:
-			log.Infof("Payment: %v in terminal state, abandoning "+
-				"shard", p.paymentHash)
+			log.Infof("Payment %v in terminal state, abandoning "+
+				"shard", p.identifier)

 			continue lifecycle

@@ -275,7 +275,7 @@ lifecycle:
 		if outcome.err != nil {
 			log.Warnf("Failed to launch shard %v for "+
 				"payment %v: %v", attempt.AttemptID,
-				p.paymentHash, outcome.err)
+				p.identifier, outcome.err)

 			// We must inspect the error to know whether it was
 			// critical or not, to decide whether we should
@@ -301,7 +301,7 @@ lifecycle:
 // shardHandler holds what is necessary to send and collect the result of
 // shards.
 type shardHandler struct {
-	paymentHash  lntypes.Hash
+	identifier   lntypes.Hash
 	router       *ChannelRouter
 	shardTracker shards.ShardTracker

@@ -398,7 +398,7 @@ func (p *shardHandler) launchShard(rt *route.Route,
 	// of the payment that we attempted to send, such that we can query the
 	// Switch for its whereabouts. The route is needed to handle the result
 	// when it eventually comes back.
-	err = p.router.cfg.Control.RegisterAttempt(p.paymentHash, attempt)
+	err = p.router.cfg.Control.RegisterAttempt(p.identifier, attempt)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -450,7 +450,7 @@ func (p *shardHandler) collectResultAsync(attempt *channeldb.HTLCAttemptInfo) {

 				log.Errorf("Error collecting result for "+
 					"shard %v for payment %v: %v",
-					attempt.AttemptID, p.paymentHash, err)
+					attempt.AttemptID, p.identifier, err)
 			}

 			select {
@@ -515,7 +515,7 @@ func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (
 	// Now ask the switch to return the result of the payment when
 	// available.
 	resultChan, err := p.router.cfg.Payer.GetPaymentResult(
-		attempt.AttemptID, p.paymentHash, errorDecryptor,
+		attempt.AttemptID, p.identifier, errorDecryptor,
 	)
 	switch {

@@ -524,9 +524,9 @@ func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (
 	// case we can safely send a new payment attempt, and wait for its
 	// result to be available.
 	case err == htlcswitch.ErrPaymentIDNotFound:
-		log.Debugf("Payment ID %v for hash %v not found in "+
+		log.Debugf("Attempt ID %v for payment %v not found in "+
 			"the Switch, retrying.", attempt.AttemptID,
-			p.paymentHash)
+			p.identifier)

 		attempt, cErr := p.failAttempt(attempt, err)
 		if cErr != nil {
@@ -582,7 +582,7 @@ func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (

 	// We successfully got a payment result back from the switch.
 	log.Debugf("Payment %v succeeded with pid=%v",
-		p.paymentHash, attempt.AttemptID)
+		p.identifier, attempt.AttemptID)

 	// Report success to mission control.
 	err = p.router.cfg.MissionControl.ReportPaymentSuccess(
@@ -596,7 +596,7 @@ 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.
 	htlcAttempt, err := p.router.cfg.Control.SettleAttempt(
-		p.paymentHash, attempt.AttemptID,
+		p.identifier, attempt.AttemptID,
 		&channeldb.HTLCSettleInfo{
 			Preimage:   result.Preimage,
 			SettleTime: p.router.cfg.Clock.Now(),
@@ -696,7 +696,7 @@ func (p *shardHandler) sendPaymentAttempt(
 	htlcAdd *lnwire.UpdateAddHTLC) error {

 	log.Tracef("Attempting to send payment %v (pid=%v), "+
-		"using route: %v", p.paymentHash, attempt.AttemptID,
+		"using route: %v", p.identifier, attempt.AttemptID,
 		newLogClosure(func() string {
 			return spew.Sdump(attempt.Route)
 		}),
@@ -712,12 +712,12 @@ func (p *shardHandler) sendPaymentAttempt(
 	if err != nil {
 		log.Errorf("Failed sending attempt %d for payment "+
 			"%v to switch: %v", attempt.AttemptID,
-			p.paymentHash, err)
+			p.identifier, err)
 		return err
 	}

 	log.Debugf("Payment %v (pid=%v) successfully sent to switch, route: %v",
-		p.paymentHash, attempt.AttemptID, &attempt.Route)
+		p.identifier, attempt.AttemptID, &attempt.Route)

 	return nil
 }
@@ -737,9 +737,9 @@ func (p *shardHandler) handleSendError(attempt *channeldb.HTLCAttemptInfo,
 	}

 	log.Infof("Payment %v failed: final_outcome=%v, raw_err=%v",
-		p.paymentHash, *reason, sendErr)
+		p.identifier, *reason, sendErr)

-	err := p.router.cfg.Control.Fail(p.paymentHash, *reason)
+	err := p.router.cfg.Control.Fail(p.identifier, *reason)
 	if err != nil {
 		return err
 	}
@@ -752,7 +752,7 @@ func (p *shardHandler) failAttempt(attempt *channeldb.HTLCAttemptInfo,
 	sendError error) (*channeldb.HTLCAttempt, error) {

 	log.Warnf("Attempt %v for payment %v failed: %v", attempt.AttemptID,
-		p.paymentHash, sendError)
+		p.identifier, sendError)

 	failInfo := marshallError(
 		sendError,
@@ -767,7 +767,7 @@ func (p *shardHandler) failAttempt(attempt *channeldb.HTLCAttemptInfo,
 	}

 	return p.router.cfg.Control.FailAttempt(
-		p.paymentHash, attempt.AttemptID,
+		p.identifier, attempt.AttemptID,
 		failInfo,
 	)
 }
--- a/routing/payment_lifecycle_test.go
+++ b/routing/payment_lifecycle_test.go
@@ -815,7 +815,7 @@ func testPaymentLifecycle(t *testing.T, test paymentLifecycleTestCase,
 		Target:      testGraph.aliasMap["c"],
 		Amount:      paymentAmt,
 		FeeLimit:    noFeeLimit,
-		PaymentHash: payHash,
+		paymentHash: &payHash,
 	}

 	// Setup our payment session source to block on release of
--- a/routing/payment_session.go
+++ b/routing/payment_session.go
@@ -171,7 +171,7 @@ func newPaymentSession(p *LightningPayment,
 		return nil, err
 	}

-	logPrefix := fmt.Sprintf("PaymentSession(%x):", p.PaymentHash)
+	logPrefix := fmt.Sprintf("PaymentSession(%x):", p.Identifier())

 	return &paymentSession{
 		additionalEdges:   edges,
--- a/routing/payment_session_test.go
+++ b/routing/payment_session_test.go
@@ -23,6 +23,11 @@ func TestRequestRoute(t *testing.T) {
 		FeeLimit:       1000,
 	}

+	var paymentHash [32]byte
+	if err := payment.SetPaymentHash(paymentHash); err != nil {
+		t.Fatal(err)
+	}
+
 	session, err := newPaymentSession(
 		payment,
 		func() (map[uint64]lnwire.MilliSatoshi,
--- a/routing/router.go
+++ b/routing/router.go
@@ -600,7 +600,7 @@ func (r *ChannelRouter) Start() error {
 	}

 	for _, payment := range payments {
-		log.Infof("Resuming payment with hash %v", payment.Info.PaymentHash)
+		log.Infof("Resuming payment %v", payment.Info.PaymentIdentifier)
 		r.wg.Add(1)
 		go func(payment *channeldb.MPPayment) {
 			defer r.wg.Done()
@@ -613,7 +613,7 @@ func (r *ChannelRouter) Start() error {
 				// We check whether the individual attempts
 				// have their HTLC hash set, if not we'll fall
 				// back to the overall payment hash.
-				hash := payment.Info.PaymentHash
+				hash := payment.Info.PaymentIdentifier
 				if a.Hash != nil {
 					hash = *a.Hash
 				}
@@ -631,30 +631,32 @@ func (r *ChannelRouter) Start() error {
 			// we don't currently persist the root share necessary
 			// to re-derive them.
 			shardTracker := shards.NewSimpleShardTracker(
-				payment.Info.PaymentHash, htlcs,
+				payment.Info.PaymentIdentifier, htlcs,
 			)

 			// We create a dummy, empty payment session such that
 			// we won't make another payment attempt when the
 			// result for the in-flight attempt is received.
 			paySession := r.cfg.SessionSource.NewPaymentSessionEmpty()
+
 			// We pass in a zero timeout value, to indicate we
 			// don't need it to timeout. It will stop immediately
 			// after the existing attempt has finished anyway. We
 			// also set a zero fee limit, as no more routes should
 			// be tried.
 			_, _, err := r.sendPayment(
-				payment.Info.Value, 0, payment.Info.PaymentHash,
-				0, paySession, shardTracker,
+				payment.Info.Value, 0,
+				payment.Info.PaymentIdentifier, 0, paySession,
+				shardTracker,
 			)
 			if err != nil {
-				log.Errorf("Resuming payment with hash %v "+
-					"failed: %v.", payment.Info.PaymentHash, err)
+				log.Errorf("Resuming payment %v failed: %v.",
+					payment.Info.PaymentIdentifier, err)
 				return
 			}

-			log.Infof("Resumed payment with hash %v completed.",
-				payment.Info.PaymentHash)
+			log.Infof("Resumed payment %v completed.",
+				payment.Info.PaymentIdentifier)
 		}(payment)
 	}

@@ -1719,9 +1721,9 @@ type LightningPayment struct {
 	// complete this payment.
 	CltvLimit uint32

-	// PaymentHash is the r-hash value to use within the HTLC extended to
-	// the first hop.
-	PaymentHash [32]byte
+	// paymentHash is the r-hash value to use within the HTLC extended to
+	// the first hop. This won't be set for AMP payments.
+	paymentHash *lntypes.Hash

 	// amp is an optional field that is set if and only if this is am AMP
 	// payment.
@@ -1801,6 +1803,20 @@ type AMPOptions struct {
 	RootShare [32]byte
 }

+// SetPaymentHash sets the given hash as the payment's overall hash. This
+// should only be used for non-AMP payments.
+func (l *LightningPayment) SetPaymentHash(hash lntypes.Hash) error {
+	l.paymentHash = &hash
+	return nil
+}
+
+// Identifier returns a 32-byte slice that uniquely identifies this single
+// payment. For non-AMP payments this will be the payment hash, for AMP
+// payments this will be the used SetID.
+func (l *LightningPayment) Identifier() [32]byte {
+	return *l.paymentHash
+}
+
 // SendPayment attempts to send a payment as described within the passed
 // LightningPayment. This function is blocking and will return either: when the
 // payment is successful, or all candidates routes have been attempted and
@@ -1822,7 +1838,7 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte,
 	// Since this is the first time this payment is being made, we pass nil
 	// for the existing attempt.
 	return r.sendPayment(
-		payment.Amount, payment.FeeLimit, payment.PaymentHash,
+		payment.Amount, payment.FeeLimit, payment.Identifier(),
 		payment.PayAttemptTimeout, paySession, shardTracker,
 	)
 }
@@ -1845,12 +1861,12 @@ func (r *ChannelRouter) SendPaymentAsync(payment *LightningPayment) error {
 			spewPayment(payment))

 		_, _, err := r.sendPayment(
-			payment.Amount, payment.FeeLimit, payment.PaymentHash,
+			payment.Amount, payment.FeeLimit, payment.Identifier(),
 			payment.PayAttemptTimeout, paySession, shardTracker,
 		)
 		if err != nil {
-			log.Errorf("Payment with hash %x failed: %v",
-				payment.PaymentHash, err)
+			log.Errorf("Payment %x failed: %v",
+				payment.Identifier(), err)
 		}
 	}()

@@ -1897,10 +1913,10 @@ func (r *ChannelRouter) preparePayment(payment *LightningPayment) (
 	//
 	// TODO(roasbeef): store records as part of creation info?
 	info := &channeldb.PaymentCreationInfo{
-		PaymentHash:    payment.PaymentHash,
-		Value:          payment.Amount,
-		CreationTime:   r.cfg.Clock.Now(),
-		PaymentRequest: payment.PaymentRequest,
+		PaymentIdentifier: payment.Identifier(),
+		Value:             payment.Amount,
+		CreationTime:      r.cfg.Clock.Now(),
+		PaymentRequest:    payment.PaymentRequest,
 	}

 	// Create a new ShardTracker that we'll use during the life cycle of
@@ -1919,11 +1935,11 @@ func (r *ChannelRouter) preparePayment(payment *LightningPayment) (
 	// the same payment hash.
 	default:
 		shardTracker = shards.NewSimpleShardTracker(
-			payment.PaymentHash, nil,
+			payment.Identifier(), nil,
 		)
 	}

-	err = r.cfg.Control.InitPayment(payment.PaymentHash, info)
+	err = r.cfg.Control.InitPayment(payment.Identifier(), info)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -1936,7 +1952,7 @@ func (r *ChannelRouter) preparePayment(payment *LightningPayment) (
 // information as it is stored in the database. For a successful htlc, this
 // information will contain the preimage. If an error occurs after the attempt
 // was initiated, both return values will be non-nil.
-func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
+func (r *ChannelRouter) SendToRoute(htlcHash lntypes.Hash, rt *route.Route) (
 	*channeldb.HTLCAttempt, error) {

 	// Calculate amount paid to receiver.
@@ -1950,16 +1966,20 @@ func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
 		amt = mpp.TotalMsat()
 	}

+	// For non-AMP payments the overall payment identifier will be the same
+	// hash as used for this HTLC.
+	paymentIdentifier := htlcHash
+
 	// Record this payment hash with the ControlTower, ensuring it is not
 	// already in-flight.
 	info := &channeldb.PaymentCreationInfo{
-		PaymentHash:    hash,
-		Value:          amt,
-		CreationTime:   r.cfg.Clock.Now(),
-		PaymentRequest: nil,
+		PaymentIdentifier: paymentIdentifier,
+		Value:             amt,
+		CreationTime:      r.cfg.Clock.Now(),
+		PaymentRequest:    nil,
 	}

-	err := r.cfg.Control.InitPayment(hash, info)
+	err := r.cfg.Control.InitPayment(paymentIdentifier, info)
 	switch {
 	// If this is an MPP attempt and the hash is already registered with
 	// the database, we can go on to launch the shard.
@@ -1970,8 +1990,8 @@ func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
 		return nil, err
 	}

-	log.Tracef("Dispatching SendToRoute for hash %v: %v",
-		hash, newLogClosure(func() string {
+	log.Tracef("Dispatching SendToRoute for HTLC hash %v: %v",
+		htlcHash, newLogClosure(func() string {
 			return spew.Sdump(rt)
 		}),
 	)
@@ -1981,12 +2001,12 @@ func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
 	// a ShardTracker that can generate hashes for AMP payments. Instead we
 	// create a simple tracker that can just return the hash for the single
 	// shard we'll now launch.
-	shardTracker := shards.NewSimpleShardTracker(hash, nil)
+	shardTracker := shards.NewSimpleShardTracker(htlcHash, nil)

 	// Launch a shard along the given route.
 	sh := &shardHandler{
 		router:       r,
-		paymentHash:  hash,
+		identifier:   paymentIdentifier,
 		shardTracker: shardTracker,
 	}

@@ -1999,10 +2019,10 @@ func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
 		err == sphinx.ErrMaxRoutingInfoSizeExceeded {

 		log.Debugf("Invalid route provided for payment %x: %v",
-			hash, err)
+			paymentIdentifier, err)

 		controlErr := r.cfg.Control.Fail(
-			hash, channeldb.FailureReasonError,
+			paymentIdentifier, channeldb.FailureReasonError,
 		)
 		if controlErr != nil {
 			return nil, controlErr
@@ -2050,7 +2070,7 @@ func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
 		reason = &r
 	}

-	err = r.cfg.Control.Fail(hash, *reason)
+	err = r.cfg.Control.Fail(paymentIdentifier, *reason)
 	if err != nil {
 		return nil, err
 	}
@@ -2075,7 +2095,7 @@ func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
 // router will call this method for every payment still in-flight according to
 // the ControlTower.
 func (r *ChannelRouter) sendPayment(
-	totalAmt, feeLimit lnwire.MilliSatoshi, paymentHash lntypes.Hash,
+	totalAmt, feeLimit lnwire.MilliSatoshi, identifier lntypes.Hash,
 	timeout time.Duration, paySession PaymentSession,
 	shardTracker shards.ShardTracker) ([32]byte, *route.Route, error) {

@@ -2092,7 +2112,7 @@ func (r *ChannelRouter) sendPayment(
 		router:        r,
 		totalAmount:   totalAmt,
 		feeLimit:      feeLimit,
-		paymentHash:   paymentHash,
+		identifier:    identifier,
 		paySession:    paySession,
 		shardTracker:  shardTracker,
 		currentHeight: currentHeight,
--- a/routing/router_test.go
+++ b/routing/router_test.go
@@ -275,13 +275,13 @@ func TestSendPaymentRouteFailureFallback(t *testing.T) {

 	// Craft a LightningPayment struct that'll send a payment from roasbeef
 	// to luo ji for 1000 satoshis, with a maximum of 1000 satoshis in fees.
-	var payHash [32]byte
+	var payHash lntypes.Hash
 	paymentAmt := lnwire.NewMSatFromSatoshis(1000)
 	payment := LightningPayment{
 		Target:      ctx.aliases["sophon"],
 		Amount:      paymentAmt,
 		FeeLimit:    noFeeLimit,
-		PaymentHash: payHash,
+		paymentHash: &payHash,
 	}

 	var preImage [32]byte
@@ -510,13 +510,13 @@ func TestSendPaymentErrorRepeatedFeeInsufficient(t *testing.T) {

 	// Craft a LightningPayment struct that'll send a payment from roasbeef
 	// to luo ji for 100 satoshis.
-	var payHash [32]byte
+	var payHash lntypes.Hash
 	amt := lnwire.NewMSatFromSatoshis(1000)
 	payment := LightningPayment{
 		Target:      ctx.aliases["sophon"],
 		Amount:      amt,
 		FeeLimit:    noFeeLimit,
-		PaymentHash: payHash,
+		paymentHash: &payHash,
 	}

 	var preImage [32]byte
@@ -611,13 +611,13 @@ func TestSendPaymentErrorNonFinalTimeLockErrors(t *testing.T) {

 	// Craft a LightningPayment struct that'll send a payment from roasbeef
 	// to sophon for 1k satoshis.
-	var payHash [32]byte
+	var payHash lntypes.Hash
 	amt := lnwire.NewMSatFromSatoshis(1000)
 	payment := LightningPayment{
 		Target:      ctx.aliases["sophon"],
 		Amount:      amt,
 		FeeLimit:    noFeeLimit,
-		PaymentHash: payHash,
+		paymentHash: &payHash,
 	}

 	var preImage [32]byte
@@ -720,7 +720,7 @@ func TestSendPaymentErrorNonFinalTimeLockErrors(t *testing.T) {
 	// Once again, Roasbeef should route around Goku since they disagree
 	// w.r.t to the block height, and instead go through Pham Nuwen. We
 	// flip a bit in the payment hash to allow resending this payment.
-	payment.PaymentHash[1] ^= 1
+	payment.paymentHash[1] ^= 1
 	paymentPreImage, rt, err = ctx.router.SendPayment(&payment)
 	if err != nil {
 		t.Fatalf("unable to send payment: %v", err)
@@ -744,13 +744,13 @@ func TestSendPaymentErrorPathPruning(t *testing.T) {

 	// Craft a LightningPayment struct that'll send a payment from roasbeef
 	// to luo ji for 1000 satoshis, with a maximum of 1000 satoshis in fees.
-	var payHash [32]byte
+	var payHash lntypes.Hash
 	paymentAmt := lnwire.NewMSatFromSatoshis(1000)
 	payment := LightningPayment{
 		Target:      ctx.aliases["sophon"],
 		Amount:      paymentAmt,
 		FeeLimit:    noFeeLimit,
-		PaymentHash: payHash,
+		paymentHash: &payHash,
 	}

 	var preImage [32]byte
@@ -887,7 +887,7 @@ func TestSendPaymentErrorPathPruning(t *testing.T) {
 		})

 	// We flip a bit in the payment hash to allow resending this payment.
-	payment.PaymentHash[1] ^= 1
+	payment.paymentHash[1] ^= 1
 	paymentPreImage, rt, err = ctx.router.SendPayment(&payment)
 	if err != nil {
 		t.Fatalf("unable to send payment: %v", err)
@@ -2565,11 +2565,12 @@ func TestUnknownErrorSource(t *testing.T) {
 	}

 	// Create a payment to node c.
+	var payHash lntypes.Hash
 	payment := LightningPayment{
 		Target:      ctx.aliases["c"],
 		Amount:      lnwire.NewMSatFromSatoshis(1000),
 		FeeLimit:    noFeeLimit,
-		PaymentHash: lntypes.Hash{},
+		paymentHash: &payHash,
 	}

 	// We'll modify the SendToSwitch method so that it simulates hop b as a
@@ -2616,7 +2617,8 @@ func TestUnknownErrorSource(t *testing.T) {

 	// Send off the payment request to the router. We expect the payment to
 	// fail because both routes have been pruned.
-	payment.PaymentHash = lntypes.Hash{1}
+	payHash = lntypes.Hash{1}
+	payment.paymentHash = &payHash
 	_, _, err = ctx.router.SendPayment(&payment)
 	if err == nil {
 		t.Fatalf("expected payment to fail")