switch+router+server: move NextPaymentID to router

This commit moves the responsibility of generating a unique payment ID
from the switch to the router. This will make it easier for the router
to keep track of which HTLCs were successfully forwarded onto the
network, as it can query the switch for existing HTLCs as long as the
paymentIDs are kept.

The router is expected to maintain a map from paymentHash->paymentID,
such that they can be replayed on restart. This also lets the router
check the status of a sent payment after a restart, by querying the
switch for the paymentID in question.

htlcswitch/link_test.go

@@ -1100,15 +1100,16 @@ func TestChannelLinkMultiHopUnknownPaymentHash(t *testing.T) {
 	// Generate payment invoice and htlc, but don't add this invoice to the
 	// receiver registry. This should trigger an unknown payment hash
 	// failure.
-	_, htlc, err := generatePayment(amount, htlcAmt, totalTimelock,
-		blob)
+	_, htlc, pid, err := generatePayment(
+		amount, htlcAmt, totalTimelock, blob,
+	)
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	// Send payment and expose err channel.
 	_, err = n.aliceServer.htlcSwitch.SendHTLC(
-		n.firstBobChannelLink.ShortChanID(), htlc,
+		n.firstBobChannelLink.ShortChanID(), pid, htlc,
 		newMockDeobfuscator(),
 	)
 	if !strings.Contains(err.Error(), lnwire.CodeUnknownPaymentHash.String()) {
@@ -1909,7 +1910,9 @@ func TestChannelLinkBandwidthConsistency(t *testing.T) {
 	// a switch initiated payment.  The resulting bandwidth should
 	// now be decremented to reflect the new HTLC.
 	htlcAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
-	invoice, htlc, err := generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
+	invoice, htlc, _, err := generatePayment(
+		htlcAmt, htlcAmt, 5, mockBlob,
+	)
 	if err != nil {
 		t.Fatalf("unable to create payment: %v", err)
 	}
@@ -1989,7 +1992,7 @@ func TestChannelLinkBandwidthConsistency(t *testing.T) {
 
 	// Next, we'll add another HTLC initiated by the switch (of the same
 	// amount as the prior one).
-	invoice, htlc, err = generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
+	invoice, htlc, _, err = generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
 	if err != nil {
 		t.Fatalf("unable to create payment: %v", err)
 	}
@@ -2075,8 +2078,9 @@ func TestChannelLinkBandwidthConsistency(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unable to gen route: %v", err)
 	}
-	invoice, htlc, err = generatePayment(htlcAmt, htlcAmt,
-		totalTimelock, blob)
+	invoice, htlc, _, err = generatePayment(
+		htlcAmt, htlcAmt, totalTimelock, blob,
+	)
 	if err != nil {
 		t.Fatalf("unable to create payment: %v", err)
 	}
@@ -2183,7 +2187,9 @@ func TestChannelLinkBandwidthConsistency(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unable to gen route: %v", err)
 	}
-	invoice, htlc, err = generatePayment(htlcAmt, htlcAmt, totalTimelock, blob)
+	invoice, htlc, _, err = generatePayment(
+		htlcAmt, htlcAmt, totalTimelock, blob,
+	)
 	if err != nil {
 		t.Fatalf("unable to create payment: %v", err)
 	}
@@ -2314,7 +2320,9 @@ func TestChannelLinkBandwidthConsistencyOverflow(t *testing.T) {
 
 	var htlcID uint64
 	addLinkHTLC := func(id uint64, amt lnwire.MilliSatoshi) [32]byte {
-		invoice, htlc, err := generatePayment(amt, amt, 5, mockBlob)
+		invoice, htlc, _, err := generatePayment(
+			amt, amt, 5, mockBlob,
+		)
 		if err != nil {
 			t.Fatalf("unable to create payment: %v", err)
 		}
@@ -2580,7 +2588,7 @@ func TestChannelLinkTrimCircuitsPending(t *testing.T) {
 	// message for the test.
 	var mockBlob [lnwire.OnionPacketSize]byte
 	htlcAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
-	_, htlc, err := generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
+	_, htlc, _, err := generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
 	if err != nil {
 		t.Fatalf("unable to create payment: %v", err)
 	}
@@ -2860,7 +2868,7 @@ func TestChannelLinkTrimCircuitsNoCommit(t *testing.T) {
 	// message for the test.
 	var mockBlob [lnwire.OnionPacketSize]byte
 	htlcAmt := lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin)
-	_, htlc, err := generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
+	_, htlc, _, err := generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
 	if err != nil {
 		t.Fatalf("unable to create payment: %v", err)
 	}
@@ -3113,7 +3121,7 @@ func TestChannelLinkBandwidthChanReserve(t *testing.T) {
 	// a switch initiated payment.  The resulting bandwidth should
 	// now be decremented to reflect the new HTLC.
 	htlcAmt := lnwire.NewMSatFromSatoshis(3 * btcutil.SatoshiPerBitcoin)
-	invoice, htlc, err := generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
+	invoice, htlc, _, err := generatePayment(htlcAmt, htlcAmt, 5, mockBlob)
 	if err != nil {
 		t.Fatalf("unable to create payment: %v", err)
 	}
@@ -3844,8 +3852,9 @@ func TestChannelLinkAcceptDuplicatePayment(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	invoice, htlc, err := generatePayment(amount, htlcAmt, totalTimelock,
-		blob)
+	invoice, htlc, pid, err := generatePayment(
+		amount, htlcAmt, totalTimelock, blob,
+	)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -3859,7 +3868,7 @@ func TestChannelLinkAcceptDuplicatePayment(t *testing.T) {
 	// payment. It should succeed w/o any issues as it has been crafted
 	// properly.
 	_, err = n.aliceServer.htlcSwitch.SendHTLC(
-		n.firstBobChannelLink.ShortChanID(), htlc,
+		n.firstBobChannelLink.ShortChanID(), pid, htlc,
 		newMockDeobfuscator(),
 	)
 	if err != nil {
@@ -3869,7 +3878,7 @@ func TestChannelLinkAcceptDuplicatePayment(t *testing.T) {
 	// Now, if we attempt to send the payment *again* it should be rejected
 	// as it's a duplicate request.
 	_, err = n.aliceServer.htlcSwitch.SendHTLC(
-		n.firstBobChannelLink.ShortChanID(), htlc,
+		n.firstBobChannelLink.ShortChanID(), pid, htlc,
 		newMockDeobfuscator(),
 	)
 	if err != ErrAlreadyPaid {
@@ -4255,7 +4264,7 @@ func generateHtlcAndInvoice(t *testing.T,
 		t.Fatalf("unable to generate route: %v", err)
 	}
 
-	invoice, htlc, err := generatePayment(
+	invoice, htlc, _, err := generatePayment(
 		htlcAmt, htlcAmt, uint32(htlcExpiry), blob,
 	)
 	if err != nil {

htlcswitch/switch.go

@@ -213,8 +213,6 @@ type Switch struct {
 	pendingPayments map[uint64]*pendingPayment
 	pendingMutex    sync.RWMutex
 
-	paymentSequencer Sequencer
-
 	// control provides verification of sending htlc mesages
 	control ControlTower
 
@@ -293,16 +291,10 @@ func New(cfg Config, currentHeight uint32) (*Switch, error) {
 		return nil, err
 	}
 
-	sequencer, err := NewPersistentSequencer(cfg.DB)
-	if err != nil {
-		return nil, err
-	}
-
 	return &Switch{
 		bestHeight:        currentHeight,
 		cfg:               &cfg,
 		circuits:          circuitMap,
-		paymentSequencer:  sequencer,
 		control:           NewPaymentControl(false, cfg.DB),
 		linkIndex:         make(map[lnwire.ChannelID]ChannelLink),
 		mailOrchestrator:  newMailOrchestrator(),
@@ -354,8 +346,9 @@ func (s *Switch) ProcessContractResolution(msg contractcourt.ResolutionMsg) erro
 }
 
 // SendHTLC is used by other subsystems which aren't belong to htlc switch
-// package in order to send the htlc update.
-func (s *Switch) SendHTLC(firstHop lnwire.ShortChannelID,
+// package in order to send the htlc update. The paymentID used MUST be unique
+// for this HTLC, otherwise the switch might reject it.
+func (s *Switch) SendHTLC(firstHop lnwire.ShortChannelID, paymentID uint64,
 	htlc *lnwire.UpdateAddHTLC,
 	deobfuscator ErrorDecrypter) ([sha256.Size]byte, error) {
 
@@ -376,11 +369,6 @@ func (s *Switch) SendHTLC(firstHop lnwire.ShortChannelID,
 		deobfuscator: deobfuscator,
 	}
 
-	paymentID, err := s.paymentSequencer.NextID()
-	if err != nil {
-		return zeroPreimage, err
-	}
-
 	s.pendingMutex.Lock()
 	s.pendingPayments[paymentID] = payment
 	s.pendingMutex.Unlock()
@@ -407,6 +395,7 @@ func (s *Switch) SendHTLC(firstHop lnwire.ShortChannelID,
 	// Returns channels so that other subsystem might wait/skip the
 	// waiting of handling of payment.
 	var preimage [sha256.Size]byte
+	var err error
 
 	select {
 	case e := <-payment.err:

htlcswitch/switch_test.go

@@ -1417,7 +1417,7 @@ func testSkipLinkLocalForward(t *testing.T, eligible bool,
 	// We'll attempt to send out a new HTLC that has Alice as the first
 	// outgoing link. This should fail as Alice isn't yet able to forward
 	// any active HTLC's.
-	_, err = s.SendHTLC(aliceChannelLink.ShortChanID(), addMsg, nil)
+	_, err = s.SendHTLC(aliceChannelLink.ShortChanID(), 0, addMsg, nil)
 	if err == nil {
 		t.Fatalf("local forward should fail due to inactive link")
 	}
@@ -1743,7 +1743,7 @@ func TestSwitchSendPayment(t *testing.T) {
 	errChan := make(chan error)
 	go func() {
 		_, err := s.SendHTLC(
-			aliceChannelLink.ShortChanID(), update,
+			aliceChannelLink.ShortChanID(), 0, update,
 			newMockDeobfuscator())
 		errChan <- err
 	}()
@@ -1752,7 +1752,7 @@ func TestSwitchSendPayment(t *testing.T) {
 		// Send the payment with the same payment hash and same
 		// amount and check that it will be propagated successfully
 		_, err := s.SendHTLC(
-			aliceChannelLink.ShortChanID(), update,
+			aliceChannelLink.ShortChanID(), 0, update,
 			newMockDeobfuscator(),
 		)
 		errChan <- err

htlcswitch/test_utils.go

@@ -543,7 +543,7 @@ func getChanID(msg lnwire.Message) (lnwire.ChannelID, error) {
 func generatePaymentWithPreimage(invoiceAmt, htlcAmt lnwire.MilliSatoshi,
 	timelock uint32, blob [lnwire.OnionPacketSize]byte,
 	preimage, rhash [32]byte) (*channeldb.Invoice, *lnwire.UpdateAddHTLC,
-	error) {
+	uint64, error) {
 
 	// Create the db invoice. Normally the payment requests needs to be set,
 	// because it is decoded in InvoiceRegistry to obtain the cltv expiry.
@@ -566,18 +566,25 @@ func generatePaymentWithPreimage(invoiceAmt, htlcAmt lnwire.MilliSatoshi,
 		OnionBlob:   blob,
 	}
 
-	return invoice, htlc, nil
+	pid, err := generateRandomBytes(8)
+	if err != nil {
+		return nil, nil, 0, err
+	}
+	paymentID := binary.BigEndian.Uint64(pid)
+
+	return invoice, htlc, paymentID, nil
 }
 
 // generatePayment generates the htlc add request by given path blob and
 // invoice which should be added by destination peer.
 func generatePayment(invoiceAmt, htlcAmt lnwire.MilliSatoshi, timelock uint32,
-	blob [lnwire.OnionPacketSize]byte) (*channeldb.Invoice, *lnwire.UpdateAddHTLC, error) {
+	blob [lnwire.OnionPacketSize]byte) (*channeldb.Invoice,
+	*lnwire.UpdateAddHTLC, uint64, error) {
 
 	var preimage [sha256.Size]byte
 	r, err := generateRandomBytes(sha256.Size)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, 0, err
 	}
 	copy(preimage[:], r)
 
@@ -772,7 +779,9 @@ func preparePayment(sendingPeer, receivingPeer lnpeer.Peer,
 	}
 
 	// Generate payment: invoice and htlc.
-	invoice, htlc, err := generatePayment(invoiceAmt, htlcAmt, timelock, blob)
+	invoice, htlc, pid, err := generatePayment(
+		invoiceAmt, htlcAmt, timelock, blob,
+	)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -786,7 +795,7 @@ func preparePayment(sendingPeer, receivingPeer lnpeer.Peer,
 	// Send payment and expose err channel.
 	return invoice, func() error {
 		_, err := sender.htlcSwitch.SendHTLC(
-			firstHop, htlc, newMockDeobfuscator(),
+			firstHop, pid, htlc, newMockDeobfuscator(),
 		)
 		return err
 	}, nil
@@ -1235,8 +1244,10 @@ func (n *twoHopNetwork) makeHoldPayment(sendingPeer, receivingPeer lnpeer.Peer,
 	rhash := preimage.Hash()
 
 	// Generate payment: invoice and htlc.
-	invoice, htlc, err := generatePaymentWithPreimage(invoiceAmt, htlcAmt, timelock, blob,
-		channeldb.UnknownPreimage, rhash)
+	invoice, htlc, pid, err := generatePaymentWithPreimage(
+		invoiceAmt, htlcAmt, timelock, blob,
+		channeldb.UnknownPreimage, rhash,
+	)
 	if err != nil {
 		paymentErr <- err
 		return paymentErr
@@ -1251,7 +1262,7 @@ func (n *twoHopNetwork) makeHoldPayment(sendingPeer, receivingPeer lnpeer.Peer,
 	// Send payment and expose err channel.
 	go func() {
 		_, err := sender.htlcSwitch.SendHTLC(
-			firstHop, htlc, newMockDeobfuscator(),
+			firstHop, pid, htlc, newMockDeobfuscator(),
 		)
 		paymentErr <- err
 	}()