github.com/decred/dcrlnd@v0.7.6/lntest/itest/lnd_routing_test.go

package itest

import (
	"bytes"
	"context"
	"encoding/hex"
	"fmt"
	"strings"
	"testing"
	"time"

	"github.com/decred/dcrd/dcrutil/v4"
	"github.com/decred/dcrd/wire"
	"github.com/decred/dcrlnd/chainreg"
	"github.com/decred/dcrlnd/lnrpc"
	"github.com/decred/dcrlnd/lnrpc/routerrpc"
	"github.com/decred/dcrlnd/lntest"
	"github.com/decred/dcrlnd/lntest/wait"
	"github.com/decred/dcrlnd/lnwire"
	"github.com/stretchr/testify/require"
	"google.golang.org/protobuf/proto"
	"matheusd.com/testctx"
)

type singleHopSendToRouteCase struct {
	name string

	// streaming tests streaming SendToRoute if true, otherwise tests
	// synchronous SenToRoute.
	streaming bool

	// routerrpc submits the request to the routerrpc subserver if true,
	// otherwise submits to the main rpc server.
	routerrpc bool
}

var singleHopSendToRouteCases = []singleHopSendToRouteCase{
	{
		name: "regular main sync",
	},
	{
		name:      "regular main stream",
		streaming: true,
	},
	{
		name:      "regular routerrpc sync",
		routerrpc: true,
	},
	{
		name: "mpp main sync",
	},
	{
		name:      "mpp main stream",
		streaming: true,
	},
	{
		name:      "mpp routerrpc sync",
		routerrpc: true,
	},
}

// testSingleHopSendToRoute tests that payments are properly processed through a
// provided route with a single hop. We'll create the following network
// topology:
//
//	Carol --100k--> Dave
//
// We'll query the daemon for routes from Carol to Dave and then send payments
// by feeding the route back into the various SendToRoute RPC methods. Here we
// test all three SendToRoute endpoints, forcing each to perform both a regular
// payment and an MPP payment.
func testSingleHopSendToRoute(net *lntest.NetworkHarness, t *harnessTest) {
	for _, test := range singleHopSendToRouteCases {
		test := test

		t.t.Run(test.name, func(t1 *testing.T) {
			ht := newHarnessTest(t1, t.lndHarness)
			ht.RunTestCase(&testCase{
				name: test.name,
				test: func(_ *lntest.NetworkHarness, tt *harnessTest) {
					testSingleHopSendToRouteCase(net, tt, test)
				},
			})
		})
	}
}

func testSingleHopSendToRouteCase(net *lntest.NetworkHarness, t *harnessTest,
	test singleHopSendToRouteCase) {

	const chanAmt = dcrutil.Amount(100000)
	const paymentAmtSat = 1000
	const numPayments = 5
	const amountPaid = int64(numPayments * paymentAmtSat)

	ctxb := context.Background()
	var networkChans []*lnrpc.ChannelPoint

	// Create Carol and Dave, then establish a channel between them. Carol
	// is the sole funder of the channel with 100k satoshis. The network
	// topology should look like:
	// Carol -> 100k -> Dave
	carol := net.NewNode(t.t, "Carol", nil)
	defer shutdownAndAssert(net, t, carol)

	dave := net.NewNode(t.t, "Dave", nil)
	defer shutdownAndAssert(net, t, dave)

	net.ConnectNodes(t.t, carol, dave)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, carol)

	// Open a channel with 100k satoshis between Carol and Dave with Carol
	// being the sole funder of the channel.
	chanPointCarol := openChannelAndAssert(
		t, net, carol, dave,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	networkChans = append(networkChans, chanPointCarol)

	carolChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointCarol)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	carolFundPoint := wire.OutPoint{
		Hash:  *carolChanTXID,
		Index: chanPointCarol.OutputIndex,
	}

	// Wait for all nodes to have seen all channels.
	nodes := []*lntest.HarnessNode{carol, dave}
	for _, chanPoint := range networkChans {
		for _, node := range nodes {
			txid, err := lnrpc.GetChanPointFundingTxid(chanPoint)
			if err != nil {
				t.Fatalf("unable to get txid: %v", err)
			}
			point := wire.OutPoint{
				Hash:  *txid,
				Index: chanPoint.OutputIndex,
			}

			err = node.WaitForNetworkChannelOpen(chanPoint)
			if err != nil {
				t.Fatalf("%s(%d): timeout waiting for "+
					"channel(%s) open: %v", node.Name(),
					node.NodeID, point, err)
			}
		}
	}

	// Create invoices for Dave, which expect a payment from Carol.
	payReqs, rHashes, _, err := createPayReqs(
		dave, paymentAmtSat, numPayments,
	)
	if err != nil {
		t.Fatalf("unable to create pay reqs: %v", err)
	}

	// Reconstruct payment addresses.
	var payAddrs [][]byte
	for _, payReq := range payReqs {
		ctx, _ := context.WithTimeout(
			context.Background(), defaultTimeout,
		)
		resp, err := dave.DecodePayReq(
			ctx,
			&lnrpc.PayReqString{PayReq: payReq},
		)
		if err != nil {
			t.Fatalf("decode pay req: %v", err)
		}
		payAddrs = append(payAddrs, resp.PaymentAddr)
	}

	// Assert Carol and Dave are synced to the chain before proceeding, to
	// ensure the queried route will have a valid final CLTV once the HTLC
	// reaches Dave.
	_, minerHeight, err := net.Miner.Node.GetBestBlock(testctx.New(t.t))
	if err != nil {
		t.Fatalf("unable to get best height: %v", err)
	}
	require.NoError(t.t, waitForNodeBlockHeight(carol, minerHeight))
	require.NoError(t.t, waitForNodeBlockHeight(dave, minerHeight))

	// Query for routes to pay from Carol to Dave using the default CLTV
	// config.
	routesReq := &lnrpc.QueryRoutesRequest{
		PubKey: dave.PubKeyStr,
		Amt:    paymentAmtSat,
	}
	ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
	routes, err := carol.QueryRoutes(ctxt, routesReq)
	if err != nil {
		t.Fatalf("unable to get route from %s: %v",
			carol.Name(), err)
	}

	// There should only be one route to try, so take the first item.
	r := routes.Routes[0]

	// Construct a closure that will set MPP fields on the route, which
	// allows us to test MPP payments.
	setMPPFields := func(i int) {
		hop := r.Hops[len(r.Hops)-1]
		hop.TlvPayload = true
		hop.MppRecord = &lnrpc.MPPRecord{
			PaymentAddr:    payAddrs[i],
			TotalAmtMAtoms: paymentAmtSat * 1000,
		}
	}

	// Construct closures for each of the payment types covered:
	//  - main rpc server sync
	//  - main rpc server streaming
	//  - routerrpc server sync
	sendToRouteSync := func() {
		for i, rHash := range rHashes {
			setMPPFields(i)

			sendReq := &lnrpc.SendToRouteRequest{
				PaymentHash: rHash,
				Route:       r,
			}
			ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
			resp, err := carol.SendToRouteSync(
				ctxt, sendReq,
			)
			if err != nil {
				t.Fatalf("unable to send to route for "+
					"%s: %v", carol.Name(), err)
			}
			if resp.PaymentError != "" {
				t.Fatalf("received payment error from %s: %v",
					carol.Name(), resp.PaymentError)
			}
		}
	}
	sendToRouteStream := func() {
		ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
		alicePayStream, err := carol.SendToRoute(ctxt) // nolint:staticcheck
		if err != nil {
			t.Fatalf("unable to create payment stream for "+
				"carol: %v", err)
		}

		for i, rHash := range rHashes {
			setMPPFields(i)

			sendReq := &lnrpc.SendToRouteRequest{
				PaymentHash: rHash,
				Route:       routes.Routes[0],
			}
			err := alicePayStream.Send(sendReq)

			if err != nil {
				t.Fatalf("unable to send payment: %v", err)
			}

			resp, err := alicePayStream.Recv()
			if err != nil {
				t.Fatalf("unable to send payment: %v", err)
			}
			if resp.PaymentError != "" {
				t.Fatalf("received payment error: %v",
					resp.PaymentError)
			}
		}
	}
	sendToRouteRouterRPC := func() {
		for i, rHash := range rHashes {
			setMPPFields(i)

			sendReq := &routerrpc.SendToRouteRequest{
				PaymentHash: rHash,
				Route:       r,
			}
			ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
			resp, err := carol.RouterClient.SendToRouteV2(
				ctxt, sendReq,
			)
			if err != nil {
				t.Fatalf("unable to send to route for "+
					"%s: %v", carol.Name(), err)
			}
			if resp.Failure != nil {
				t.Fatalf("received payment error from %s: %v",
					carol.Name(), resp.Failure)
			}
		}
	}

	// Using Carol as the node as the source, send the payments
	// synchronously via the the routerrpc's SendToRoute, or via the main RPC
	// server's SendToRoute streaming or sync calls.
	switch {
	case !test.routerrpc && test.streaming:
		sendToRouteStream()
	case !test.routerrpc && !test.streaming:
		sendToRouteSync()
	case test.routerrpc && !test.streaming:
		sendToRouteRouterRPC()
	default:
		t.Fatalf("routerrpc does not support streaming send_to_route")
	}

	// Verify that the payment's from Carol's PoV have the correct payment
	// hash and amount.
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	paymentsResp, err := carol.ListPayments(
		ctxt, &lnrpc.ListPaymentsRequest{},
	)
	if err != nil {
		t.Fatalf("error when obtaining %s payments: %v",
			carol.Name(), err)
	}
	if len(paymentsResp.Payments) != numPayments {
		t.Fatalf("incorrect number of payments, got %v, want %v",
			len(paymentsResp.Payments), numPayments)
	}

	for i, p := range paymentsResp.Payments {
		// Assert that the payment hashes for each payment match up.
		rHashHex := hex.EncodeToString(rHashes[i])
		if p.PaymentHash != rHashHex {
			t.Fatalf("incorrect payment hash for payment %d, "+
				"want: %s got: %s",
				i, rHashHex, p.PaymentHash)
		}

		// Assert that each payment has no invoice since the payment was
		// completed using SendToRoute.
		if p.PaymentRequest != "" {
			t.Fatalf("incorrect payment request for payment: %d, "+
				"want: \"\", got: %s",
				i, p.PaymentRequest)
		}

		// Assert the payment amount is correct.
		if p.ValueAtoms != paymentAmtSat {
			t.Fatalf("incorrect payment amt for payment %d, "+
				"want: %d, got: %d",
				i, paymentAmtSat, p.ValueAtoms)
		}

		// Assert exactly one htlc was made.
		if len(p.Htlcs) != 1 {
			t.Fatalf("expected 1 htlc for payment %d, got: %d",
				i, len(p.Htlcs))
		}

		// Assert the htlc's route is populated.
		htlc := p.Htlcs[0]
		if htlc.Route == nil {
			t.Fatalf("expected route for payment %d", i)
		}

		// Assert the hop has exactly one hop.
		if len(htlc.Route.Hops) != 1 {
			t.Fatalf("expected 1 hop for payment %d, got: %d",
				i, len(htlc.Route.Hops))
		}

		// If this is an MPP test, assert the MPP record's fields are
		// properly populated. Otherwise the hop should not have an MPP
		// record.
		hop := htlc.Route.Hops[0]
		if hop.MppRecord == nil {
			t.Fatalf("expected mpp record for mpp payment")
		}

		if hop.MppRecord.TotalAmtMAtoms != paymentAmtSat*1000 {
			t.Fatalf("incorrect mpp total msat for payment %d "+
				"want: %d, got: %d",
				i, paymentAmtSat*1000,
				hop.MppRecord.TotalAmtMAtoms)
		}

		expAddr := payAddrs[i]
		if !bytes.Equal(hop.MppRecord.PaymentAddr, expAddr) {
			t.Fatalf("incorrect mpp payment addr for payment %d "+
				"want: %x, got: %x",
				i, expAddr, hop.MppRecord.PaymentAddr)
		}
	}

	// Verify that the invoices's from Dave's PoV have the correct payment
	// hash and amount.
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	invoicesResp, err := dave.ListInvoices(
		ctxt, &lnrpc.ListInvoiceRequest{},
	)
	if err != nil {
		t.Fatalf("error when obtaining %s payments: %v",
			dave.Name(), err)
	}
	if len(invoicesResp.Invoices) != numPayments {
		t.Fatalf("incorrect number of invoices, got %v, want %v",
			len(invoicesResp.Invoices), numPayments)
	}

	for i, inv := range invoicesResp.Invoices {
		// Assert that the payment hashes match up.
		if !bytes.Equal(inv.RHash, rHashes[i]) {
			t.Fatalf("incorrect payment hash for invoice %d, "+
				"want: %x got: %x",
				i, rHashes[i], inv.RHash)
		}

		// Assert that the amount paid to the invoice is correct.
		if inv.AmtPaidAtoms != paymentAmtSat {
			t.Fatalf("incorrect payment amt for invoice %d, "+
				"want: %d, got %d",
				i, paymentAmtSat, inv.AmtPaidAtoms)
		}
	}

	// At this point all the channels within our proto network should be
	// shifted by 5k satoshis in the direction of Dave, the sink within the
	// payment flow generated above. The order of asserts corresponds to
	// increasing of time is needed to embed the HTLC in commitment
	// transaction, in channel Carol->Dave, order is Dave and then Carol.
	assertAmountPaid(t, "Carol(local) => Dave(remote)", dave,
		carolFundPoint, int64(0), amountPaid)
	assertAmountPaid(t, "Carol(local) => Dave(remote)", carol,
		carolFundPoint, amountPaid, int64(0))

	closeChannelAndAssert(t, net, carol, chanPointCarol, false)
}

// testMultiHopSendToRoute tests that payments are properly processed
// through a provided route. We'll create the following network topology:
//
//	Alice --100k--> Bob --100k--> Carol
//
// We'll query the daemon for routes from Alice to Carol and then
// send payments through the routes.
func testMultiHopSendToRoute(net *lntest.NetworkHarness, t *harnessTest) {
	t.t.Run("with cache", func(tt *testing.T) {
		ht := newHarnessTest(tt, t.lndHarness)
		runMultiHopSendToRoute(net, ht, true)
	})
	if *dbBackendFlag == "bbolt" {
		t.t.Run("without cache", func(tt *testing.T) {
			ht := newHarnessTest(tt, t.lndHarness)
			runMultiHopSendToRoute(net, ht, false)
		})
	}
}

// runMultiHopSendToRoute tests that payments are properly processed
// through a provided route. We'll create the following network topology:
//
//	Alice --100k--> Bob --100k--> Carol
//
// We'll query the daemon for routes from Alice to Carol and then
// send payments through the routes.
func runMultiHopSendToRoute(net *lntest.NetworkHarness, t *harnessTest,
	useGraphCache bool) {

	ctxb := context.Background()

	var opts []string
	if !useGraphCache {
		opts = append(opts, "--db.no-graph-cache")
	}

	alice := net.NewNode(t.t, "Alice", opts)
	defer shutdownAndAssert(net, t, alice)

	net.ConnectNodes(t.t, alice, net.Bob)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, alice)

	const chanAmt = dcrutil.Amount(100000)
	var networkChans []*lnrpc.ChannelPoint

	// Open a channel with 100k satoshis between Alice and Bob with Alice
	// being the sole funder of the channel.
	chanPointAlice := openChannelAndAssert(
		t, net, alice, net.Bob,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	networkChans = append(networkChans, chanPointAlice)

	aliceChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointAlice)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	aliceFundPoint := wire.OutPoint{
		Hash:  *aliceChanTXID,
		Index: chanPointAlice.OutputIndex,
	}

	// Create Carol and establish a channel from Bob. Bob is the sole funder
	// of the channel with 100k satoshis. The network topology should look like:
	// Alice -> Bob -> Carol
	carol := net.NewNode(t.t, "Carol", nil)
	defer shutdownAndAssert(net, t, carol)

	net.ConnectNodes(t.t, carol, net.Bob)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, net.Bob)

	chanPointBob := openChannelAndAssert(
		t, net, net.Bob, carol,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	networkChans = append(networkChans, chanPointBob)
	bobChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointBob)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	bobFundPoint := wire.OutPoint{
		Hash:  *bobChanTXID,
		Index: chanPointBob.OutputIndex,
	}

	// Wait for all nodes to have seen all channels.
	nodes := []*lntest.HarnessNode{alice, net.Bob, carol}
	nodeNames := []string{"Alice", "Bob", "Carol"}
	for _, chanPoint := range networkChans {
		for i, node := range nodes {
			txid, err := lnrpc.GetChanPointFundingTxid(chanPoint)
			if err != nil {
				t.Fatalf("unable to get txid: %v", err)
			}
			point := wire.OutPoint{
				Hash:  *txid,
				Index: chanPoint.OutputIndex,
			}

			err = node.WaitForNetworkChannelOpen(chanPoint)
			if err != nil {
				t.Fatalf("%s(%d): timeout waiting for "+
					"channel(%s) open: %v", nodeNames[i],
					node.NodeID, point, err)
			}
		}
	}

	// Create 5 invoices for Carol, which expect a payment from Alice for 1k
	// satoshis with a different preimage each time.
	const (
		numPayments = 5
		paymentAmt  = 1000
	)
	_, rHashes, invoices, err := createPayReqs(
		carol, paymentAmt, numPayments,
	)
	if err != nil {
		t.Fatalf("unable to create pay reqs: %v", err)
	}

	// Construct a route from Alice to Carol for each of the invoices
	// created above.  We set FinalCltvDelta to 40 since by default
	// QueryRoutes returns the last hop with a final cltv delta of 9 where
	// as the default in htlcswitch is 40.
	routesReq := &lnrpc.QueryRoutesRequest{
		PubKey:         carol.PubKeyStr,
		Amt:            paymentAmt,
		FinalCltvDelta: chainreg.DefaultDecredTimeLockDelta,
	}
	ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
	routes, err := alice.QueryRoutes(ctxt, routesReq)
	if err != nil {
		t.Fatalf("unable to get route: %v", err)
	}

	// We'll wait for all parties to recognize the new channels within the
	// network.
	err = carol.WaitForNetworkChannelOpen(chanPointBob)
	if err != nil {
		t.Fatalf("bob didn't advertise his channel in time: %v", err)
	}

	time.Sleep(time.Millisecond * 50)

	// Using Alice as the source, pay to the 5 invoices from Carol created
	// above.
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)

	for i, rHash := range rHashes {
		// Manually set the MPP payload a new for each payment since
		// the payment addr will change with each invoice, although we
		// can re-use the route itself.
		route := *routes.Routes[0]
		route.Hops[len(route.Hops)-1].TlvPayload = true
		route.Hops[len(route.Hops)-1].MppRecord = &lnrpc.MPPRecord{
			PaymentAddr: invoices[i].PaymentAddr,
			TotalAmtMAtoms: int64(
				lnwire.NewMAtomsFromAtoms(paymentAmt),
			),
		}

		sendReq := &routerrpc.SendToRouteRequest{
			PaymentHash: rHash,
			Route:       &route,
		}
		resp, err := alice.RouterClient.SendToRouteV2(ctxt, sendReq)
		if err != nil {
			t.Fatalf("unable to send payment: %v", err)
		}

		if resp.Failure != nil {
			t.Fatalf("received payment error: %v", resp.Failure)
		}
	}

	// When asserting the amount of satoshis moved, we'll factor in the
	// default base fee, as we didn't modify the fee structure when
	// creating the seed nodes in the network.
	const baseFee = 1

	// At this point all the channels within our proto network should be
	// shifted by 5k satoshis in the direction of Carol, the sink within the
	// payment flow generated above. The order of asserts corresponds to
	// increasing of time is needed to embed the HTLC in commitment
	// transaction, in channel Alice->Bob->Carol, order is Carol, Bob,
	// Alice.
	const amountPaid = int64(5000)
	assertAmountPaid(t, "Bob(local) => Carol(remote)", carol,
		bobFundPoint, int64(0), amountPaid)
	assertAmountPaid(t, "Bob(local) => Carol(remote)", net.Bob,
		bobFundPoint, amountPaid, int64(0))
	assertAmountPaid(t, "Alice(local) => Bob(remote)", net.Bob,
		aliceFundPoint, int64(0), amountPaid+(baseFee*numPayments))
	assertAmountPaid(t, "Alice(local) => Bob(remote)", alice,
		aliceFundPoint, amountPaid+(baseFee*numPayments), int64(0))

	closeChannelAndAssert(t, net, alice, chanPointAlice, false)
	closeChannelAndAssert(t, net, carol, chanPointBob, false)
}

// testSendToRouteErrorPropagation tests propagation of errors that occur
// while processing a multi-hop payment through an unknown route.
func testSendToRouteErrorPropagation(net *lntest.NetworkHarness, t *harnessTest) {
	ctxb := context.Background()

	const chanAmt = dcrutil.Amount(100000)

	// Open a channel with 100k satoshis between Alice and Bob with Alice
	// being the sole funder of the channel.
	chanPointAlice := openChannelAndAssert(
		t, net, net.Alice, net.Bob,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)

	err := net.Alice.WaitForNetworkChannelOpen(chanPointAlice)
	if err != nil {
		t.Fatalf("alice didn't advertise her channel: %v", err)
	}

	// Create a new nodes (Carol and Charlie), load her with some funds,
	// then establish a connection between Carol and Charlie with a channel
	// that has identical capacity to the one created above.Then we will
	// get route via queryroutes call which will be fake route for Alice ->
	// Bob graph.
	//
	// The network topology should now look like: Alice -> Bob; Carol -> Charlie.
	carol := net.NewNode(t.t, "Carol", nil)
	defer shutdownAndAssert(net, t, carol)

	net.SendCoins(t.t, dcrutil.AtomsPerCoin, carol)

	charlie := net.NewNode(t.t, "Charlie", nil)
	defer shutdownAndAssert(net, t, charlie)

	net.SendCoins(t.t, dcrutil.AtomsPerCoin, charlie)

	net.ConnectNodes(t.t, carol, charlie)

	chanPointCarol := openChannelAndAssert(
		t, net, carol, charlie,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	err = carol.WaitForNetworkChannelOpen(chanPointCarol)
	if err != nil {
		t.Fatalf("carol didn't advertise her channel: %v", err)
	}

	// Query routes from Carol to Charlie which will be an invalid route
	// for Alice -> Bob.
	fakeReq := &lnrpc.QueryRoutesRequest{
		PubKey: charlie.PubKeyStr,
		Amt:    int64(1),
	}
	ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
	fakeRoute, err := carol.QueryRoutes(ctxt, fakeReq)
	if err != nil {
		t.Fatalf("unable get fake route: %v", err)
	}

	// Create 1 invoices for Bob, which expect a payment from Alice for 1k
	// satoshis
	const paymentAmt = 1000

	invoice := &lnrpc.Invoice{
		Memo:  "testing",
		Value: paymentAmt,
	}
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	resp, err := net.Bob.AddInvoice(ctxt, invoice)
	if err != nil {
		t.Fatalf("unable to add invoice: %v", err)
	}

	rHash := resp.RHash

	// Using Alice as the source, pay to the 5 invoices from Bob created above.
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	alicePayStream, err := net.Alice.SendToRoute(ctxt)
	if err != nil {
		t.Fatalf("unable to create payment stream for alice: %v", err)
	}

	sendReq := &lnrpc.SendToRouteRequest{
		PaymentHash: rHash,
		Route:       fakeRoute.Routes[0],
	}

	if err := alicePayStream.Send(sendReq); err != nil {
		t.Fatalf("unable to send payment: %v", err)
	}

	// At this place we should get an rpc error with notification
	// that edge is not found on hop(0)
	if _, err := alicePayStream.Recv(); err != nil && strings.Contains(err.Error(),
		"edge not found") {

	} else if err != nil {
		t.Fatalf("payment stream has been closed but fake route has consumed: %v", err)
	}

	closeChannelAndAssert(t, net, net.Alice, chanPointAlice, false)
	closeChannelAndAssert(t, net, carol, chanPointCarol, false)
}

// testPrivateChannels tests that a private channel can be used for
// routing by the two endpoints of the channel, but is not known by
// the rest of the nodes in the graph.
func testPrivateChannels(net *lntest.NetworkHarness, t *harnessTest) {
	ctxb := context.Background()

	const chanAmt = dcrutil.Amount(100000)
	var networkChans []*lnrpc.ChannelPoint

	// We create the following topology:
	//
	// Dave --100k--> Alice --200k--> Bob
	//  ^		    ^
	//  |		    |
	// 100k		   100k
	//  |		    |
	//  +---- Carol ----+
	//
	// where the 100k channel between Carol and Alice is private.

	// Open a channel with 200k satoshis between Alice and Bob.
	chanPointAlice := openChannelAndAssert(
		t, net, net.Alice, net.Bob,
		lntest.OpenChannelParams{
			Amt: chanAmt * 2,
		},
	)
	networkChans = append(networkChans, chanPointAlice)

	aliceChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointAlice)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	aliceFundPoint := wire.OutPoint{
		Hash:  *aliceChanTXID,
		Index: chanPointAlice.OutputIndex,
	}

	// Create Dave, and a channel to Alice of 100k.
	dave := net.NewNode(t.t, "Dave", nil)
	defer shutdownAndAssert(net, t, dave)

	net.ConnectNodes(t.t, dave, net.Alice)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, dave)

	chanPointDave := openChannelAndAssert(
		t, net, dave, net.Alice,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	networkChans = append(networkChans, chanPointDave)
	daveChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointDave)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	daveFundPoint := wire.OutPoint{
		Hash:  *daveChanTXID,
		Index: chanPointDave.OutputIndex,
	}

	// Next, we'll create Carol and establish a channel from her to
	// Dave of 100k.
	carol := net.NewNode(t.t, "Carol", nil)
	defer shutdownAndAssert(net, t, carol)

	net.ConnectNodes(t.t, carol, dave)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, carol)

	chanPointCarol := openChannelAndAssert(
		t, net, carol, dave,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	networkChans = append(networkChans, chanPointCarol)

	carolChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointCarol)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	carolFundPoint := wire.OutPoint{
		Hash:  *carolChanTXID,
		Index: chanPointCarol.OutputIndex,
	}

	// Wait for all nodes to have seen all these channels, as they
	// are all public.
	nodes := []*lntest.HarnessNode{net.Alice, net.Bob, carol, dave}
	nodeNames := []string{"Alice", "Bob", "Carol", "Dave"}
	for _, chanPoint := range networkChans {
		for i, node := range nodes {
			txid, err := lnrpc.GetChanPointFundingTxid(chanPoint)
			if err != nil {
				t.Fatalf("unable to get txid: %v", err)
			}
			point := wire.OutPoint{
				Hash:  *txid,
				Index: chanPoint.OutputIndex,
			}

			err = node.WaitForNetworkChannelOpen(chanPoint)
			if err != nil {
				t.Fatalf("%s(%d): timeout waiting for "+
					"channel(%s) open: %v", nodeNames[i],
					node.NodeID, point, err)
			}
		}
	}
	// Now create a _private_ channel directly between Carol and
	// Alice of 100k.
	net.ConnectNodes(t.t, carol, net.Alice)
	chanOpenUpdate := openChannelStream(
		t, net, carol, net.Alice,
		lntest.OpenChannelParams{
			Amt:     chanAmt,
			Private: true,
		},
	)
	if err != nil {
		t.Fatalf("unable to open channel: %v", err)
	}

	// One block is enough to make the channel ready for use, since the
	// nodes have defaultNumConfs=1 set.
	block := mineBlocks(t, net, 1, 1)[0]

	chanPointPrivate, err := net.WaitForChannelOpen(chanOpenUpdate)
	if err != nil {
		t.Fatalf("error while waiting for channel open: %v", err)
	}
	fundingTxID, err := lnrpc.GetChanPointFundingTxid(chanPointPrivate)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	assertTxInBlock(t, block, fundingTxID)

	// The channel should be listed in the peer information returned by
	// both peers.
	privateFundPoint := wire.OutPoint{
		Hash:  *fundingTxID,
		Index: chanPointPrivate.OutputIndex,
	}
	err = net.AssertChannelExists(carol, &privateFundPoint)
	if err != nil {
		t.Fatalf("unable to assert channel existence: %v", err)
	}
	err = net.AssertChannelExists(net.Alice, &privateFundPoint)
	if err != nil {
		t.Fatalf("unable to assert channel existence: %v", err)
	}

	// The channel should be available for payments between Carol and Alice.
	// We check this by sending payments from Carol to Bob, that
	// collectively would deplete at least one of Carol's channels.

	// Create 2 invoices for Bob, each of 70k satoshis. Since each of
	// Carol's channels is of size 100k, these payments cannot succeed
	// by only using one of the channels.
	const numPayments = 2
	const paymentAmt = 70000
	payReqs, _, _, err := createPayReqs(
		net.Bob, paymentAmt, numPayments,
	)
	if err != nil {
		t.Fatalf("unable to create pay reqs: %v", err)
	}

	time.Sleep(time.Millisecond * 50)

	// Let Carol pay the invoices.
	err = completePaymentRequests(carol, carol.RouterClient, payReqs, true)
	if err != nil {
		t.Fatalf("unable to send payments: %v", err)
	}

	// When asserting the amount of satoshis moved, we'll factor in the
	// default base fee, as we didn't modify the fee structure when
	// creating the seed nodes in the network.
	const baseFee = 1

	// Bob should have received 140k satoshis from Alice.
	assertAmountPaid(t, "Alice(local) => Bob(remote)", net.Bob,
		aliceFundPoint, int64(0), 2*paymentAmt)

	// Alice sent 140k to Bob.
	assertAmountPaid(t, "Alice(local) => Bob(remote)", net.Alice,
		aliceFundPoint, 2*paymentAmt, int64(0))

	// Alice received 70k + fee from Dave.
	assertAmountPaid(t, "Dave(local) => Alice(remote)", net.Alice,
		daveFundPoint, int64(0), paymentAmt+baseFee)

	// Dave sent 70k+fee to Alice.
	assertAmountPaid(t, "Dave(local) => Alice(remote)", dave,
		daveFundPoint, paymentAmt+baseFee, int64(0))

	// Dave received 70k+fee of two hops from Carol.
	assertAmountPaid(t, "Carol(local) => Dave(remote)", dave,
		carolFundPoint, int64(0), paymentAmt+baseFee*2)

	// Carol sent 70k+fee of two hops to Dave.
	assertAmountPaid(t, "Carol(local) => Dave(remote)", carol,
		carolFundPoint, paymentAmt+baseFee*2, int64(0))

	// Alice received 70k+fee from Carol.
	assertAmountPaid(t, "Carol(local) [private=>] Alice(remote)",
		net.Alice, privateFundPoint, int64(0), paymentAmt+baseFee)

	// Carol sent 70k+fee to Alice.
	assertAmountPaid(t, "Carol(local) [private=>] Alice(remote)",
		carol, privateFundPoint, paymentAmt+baseFee, int64(0))

	// Alice should also be able to route payments using this channel,
	// so send two payments of 60k back to Carol.
	const paymentAmt60k = 60000
	payReqs, _, _, err = createPayReqs(
		carol, paymentAmt60k, numPayments,
	)
	if err != nil {
		t.Fatalf("unable to create pay reqs: %v", err)
	}

	time.Sleep(time.Millisecond * 50)

	// Let Bob pay the invoices.
	err = completePaymentRequests(
		net.Alice, net.Alice.RouterClient, payReqs, true,
	)
	if err != nil {
		t.Fatalf("unable to send payments: %v", err)
	}

	// Finally, we make sure Dave and Bob does not know about the
	// private channel between Carol and Alice. We first mine
	// plenty of blocks, such that the channel would have been
	// announced in case it was public.
	mineBlocks(t, net, 10, 0)

	// We create a helper method to check how many edges each of the
	// nodes know about. Carol and Alice should know about 4, while
	// Bob and Dave should only know about 3, since one channel is
	// private.
	numChannels := func(node *lntest.HarnessNode, includeUnannounced bool) int {
		req := &lnrpc.ChannelGraphRequest{
			IncludeUnannounced: includeUnannounced,
		}
		ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
		chanGraph, err := node.DescribeGraph(ctxt, req)
		if err != nil {
			t.Fatalf("unable go describegraph: %v", err)
		}
		return len(chanGraph.Edges)
	}

	var predErr error
	err = wait.Predicate(func() bool {
		aliceChans := numChannels(net.Alice, true)
		if aliceChans != 4 {
			predErr = fmt.Errorf("expected Alice to know 4 edges, "+
				"had %v", aliceChans)
			return false
		}
		alicePubChans := numChannels(net.Alice, false)
		if alicePubChans != 3 {
			predErr = fmt.Errorf("expected Alice to know 3 public edges, "+
				"had %v", alicePubChans)
			return false
		}
		bobChans := numChannels(net.Bob, true)
		if bobChans != 3 {
			predErr = fmt.Errorf("expected Bob to know 3 edges, "+
				"had %v", bobChans)
			return false
		}
		carolChans := numChannels(carol, true)
		if carolChans != 4 {
			predErr = fmt.Errorf("expected Carol to know 4 edges, "+
				"had %v", carolChans)
			return false
		}
		carolPubChans := numChannels(carol, false)
		if carolPubChans != 3 {
			predErr = fmt.Errorf("expected Carol to know 3 public edges, "+
				"had %v", carolPubChans)
			return false
		}
		daveChans := numChannels(dave, true)
		if daveChans != 3 {
			predErr = fmt.Errorf("expected Dave to know 3 edges, "+
				"had %v", daveChans)
			return false
		}
		return true
	}, defaultTimeout)
	if err != nil {
		t.Fatalf("%v", predErr)
	}

	// Close all channels.
	closeChannelAndAssert(t, net, net.Alice, chanPointAlice, false)
	closeChannelAndAssert(t, net, dave, chanPointDave, false)
	closeChannelAndAssert(t, net, carol, chanPointCarol, false)
	closeChannelAndAssert(t, net, carol, chanPointPrivate, false)
}

// testInvoiceRoutingHints tests that the routing hints for an invoice are
// created properly.
func testInvoiceRoutingHints(net *lntest.NetworkHarness, t *harnessTest) {
	ctxb := context.Background()

	const chanAmt = dcrutil.Amount(100000)

	// Throughout this test, we'll be opening a channel between Alice and
	// several other parties.
	//
	// First, we'll create a private channel between Alice and Bob. This
	// will be the only channel that will be considered as a routing hint
	// throughout this test. We'll include a push amount since we currently
	// require channels to have enough remote balance to cover the invoice's
	// payment.
	chanPointBob := openChannelAndAssert(
		t, net, net.Alice, net.Bob,
		lntest.OpenChannelParams{
			Amt:     chanAmt,
			PushAmt: chanAmt / 2,
			Private: true,
		},
	)

	// Then, we'll create Carol's node and open a public channel between her
	// and Alice. This channel will not be considered as a routing hint due
	// to it being public.
	carol := net.NewNode(t.t, "Carol", nil)
	defer shutdownAndAssert(net, t, carol)

	net.ConnectNodes(t.t, net.Alice, carol)
	chanPointCarol := openChannelAndAssert(
		t, net, net.Alice, carol,
		lntest.OpenChannelParams{
			Amt:     chanAmt,
			PushAmt: chanAmt / 2,
		},
	)

	// We'll also create a public channel between Bob and Carol to ensure
	// that Bob gets selected as the only routing hint. We do this as
	// we should only include routing hints for nodes that are publicly
	// advertised, otherwise we'd end up leaking information about nodes
	// that wish to stay unadvertised.
	net.ConnectNodes(t.t, net.Bob, carol)
	chanPointBobCarol := openChannelAndAssert(
		t, net, net.Bob, carol,
		lntest.OpenChannelParams{
			Amt:     chanAmt,
			PushAmt: chanAmt / 2,
		},
	)

	// Then, we'll create Dave's node and open a private channel between him
	// and Alice. We will not include a push amount in order to not consider
	// this channel as a routing hint as it will not have enough remote
	// balance for the invoice's amount.
	dave := net.NewNode(t.t, "Dave", nil)
	defer shutdownAndAssert(net, t, dave)

	net.ConnectNodes(t.t, net.Alice, dave)
	chanPointDave := openChannelAndAssert(
		t, net, net.Alice, dave,
		lntest.OpenChannelParams{
			Amt:     chanAmt,
			Private: true,
		},
	)

	// Finally, we'll create Eve's node and open a private channel between
	// her and Alice. This time though, we'll take Eve's node down after the
	// channel has been created to avoid populating routing hints for
	// inactive channels.
	eve := net.NewNode(t.t, "Eve", nil)
	net.ConnectNodes(t.t, net.Alice, eve)
	chanPointEve := openChannelAndAssert(
		t, net, net.Alice, eve,
		lntest.OpenChannelParams{
			Amt:     chanAmt,
			PushAmt: chanAmt / 2,
			Private: true,
		},
	)

	// Make sure all the channels have been opened.
	chanNames := []string{
		"alice-bob", "alice-carol", "bob-carol", "alice-dave",
		"alice-eve",
	}
	aliceChans := []*lnrpc.ChannelPoint{
		chanPointBob, chanPointCarol, chanPointBobCarol, chanPointDave,
		chanPointEve,
	}
	for i, chanPoint := range aliceChans {
		err := net.Alice.WaitForNetworkChannelOpen(chanPoint)
		if err != nil {
			t.Fatalf("timed out waiting for channel open %s: %v",
				chanNames[i], err)
		}
	}

	// Now that the channels are open, we'll take down Eve's node.
	shutdownAndAssert(net, t, eve)

	// Create an invoice for Alice that will populate the routing hints.
	invoice := &lnrpc.Invoice{
		Memo:    "routing hints",
		Value:   int64(chanAmt / 4),
		Private: true,
	}

	// Due to the way the channels were set up above, the channel between
	// Alice and Bob should be the only channel used as a routing hint.
	var predErr error
	var decoded *lnrpc.PayReq
	err := wait.Predicate(func() bool {
		ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
		resp, err := net.Alice.AddInvoice(ctxt, invoice)
		if err != nil {
			predErr = fmt.Errorf("unable to add invoice: %v", err)
			return false
		}

		// We'll decode the invoice's payment request to determine which
		// channels were used as routing hints.
		payReq := &lnrpc.PayReqString{
			PayReq: resp.PaymentRequest,
		}
		ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
		decoded, err = net.Alice.DecodePayReq(ctxt, payReq)
		if err != nil {
			predErr = fmt.Errorf("unable to decode payment "+
				"request: %v", err)
			return false
		}

		if len(decoded.RouteHints) != 1 {
			predErr = fmt.Errorf("expected one route hint, got %d",
				len(decoded.RouteHints))
			return false
		}
		return true
	}, defaultTimeout)
	if err != nil {
		t.Fatalf(predErr.Error())
	}

	hops := decoded.RouteHints[0].HopHints
	if len(hops) != 1 {
		t.Fatalf("expected one hop in route hint, got %d", len(hops))
	}
	chanID := hops[0].ChanId

	// We'll need the short channel ID of the channel between Alice and Bob
	// to make sure the routing hint is for this channel.
	listReq := &lnrpc.ListChannelsRequest{}
	ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
	listResp, err := net.Alice.ListChannels(ctxt, listReq)
	if err != nil {
		t.Fatalf("unable to retrieve alice's channels: %v", err)
	}

	var aliceBobChanID uint64
	for _, channel := range listResp.Channels {
		if channel.RemotePubkey == net.Bob.PubKeyStr {
			aliceBobChanID = channel.ChanId
		}
	}

	if aliceBobChanID == 0 {
		t.Fatalf("channel between alice and bob not found")
	}

	if chanID != aliceBobChanID {
		t.Fatalf("expected channel ID %d, got %d", aliceBobChanID,
			chanID)
	}

	// Now that we've confirmed the routing hints were added correctly, we
	// can close all the channels and shut down all the nodes created.
	closeChannelAndAssert(t, net, net.Alice, chanPointBob, false)
	closeChannelAndAssert(t, net, net.Alice, chanPointCarol, false)
	closeChannelAndAssert(t, net, net.Bob, chanPointBobCarol, false)
	closeChannelAndAssert(t, net, net.Alice, chanPointDave, false)

	// The channel between Alice and Eve should be force closed since Eve
	// is offline.
	closeChannelAndAssert(t, net, net.Alice, chanPointEve, true)

	// Cleanup by mining the force close and sweep transaction.
	cleanupForceClose(t, net, net.Alice, chanPointEve)
}

// testMultiHopOverPrivateChannels tests that private channels can be used as
// intermediate hops in a route for payments.
func testMultiHopOverPrivateChannels(net *lntest.NetworkHarness, t *harnessTest) {
	ctxb := context.Background()

	// We'll test that multi-hop payments over private channels work as
	// intended. To do so, we'll create the following topology:
	//         private        public           private
	// Alice <--100k--> Bob <--100k--> Carol <--100k--> Dave
	const chanAmt = dcrutil.Amount(100000)

	// First, we'll open a private channel between Alice and Bob with Alice
	// being the funder.
	chanPointAlice := openChannelAndAssert(
		t, net, net.Alice, net.Bob,
		lntest.OpenChannelParams{
			Amt:     chanAmt,
			Private: true,
		},
	)

	err := net.Alice.WaitForNetworkChannelOpen(chanPointAlice)
	if err != nil {
		t.Fatalf("alice didn't see the channel alice <-> bob before "+
			"timeout: %v", err)
	}
	err = net.Bob.WaitForNetworkChannelOpen(chanPointAlice)
	if err != nil {
		t.Fatalf("bob didn't see the channel alice <-> bob before "+
			"timeout: %v", err)
	}

	// Retrieve Alice's funding outpoint.
	aliceChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointAlice)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	aliceFundPoint := wire.OutPoint{
		Hash:  *aliceChanTXID,
		Index: chanPointAlice.OutputIndex,
	}

	// Next, we'll create Carol's node and open a public channel between
	// her and Bob with Bob being the funder.
	carol := net.NewNode(t.t, "Carol", nil)
	defer shutdownAndAssert(net, t, carol)

	net.ConnectNodes(t.t, net.Bob, carol)
	chanPointBob := openChannelAndAssert(
		t, net, net.Bob, carol,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)

	err = net.Bob.WaitForNetworkChannelOpen(chanPointBob)
	if err != nil {
		t.Fatalf("bob didn't see the channel bob <-> carol before "+
			"timeout: %v", err)
	}
	err = carol.WaitForNetworkChannelOpen(chanPointBob)
	if err != nil {
		t.Fatalf("carol didn't see the channel bob <-> carol before "+
			"timeout: %v", err)
	}
	err = net.Alice.WaitForNetworkChannelOpen(chanPointBob)
	if err != nil {
		t.Fatalf("alice didn't see the channel bob <-> carol before "+
			"timeout: %v", err)
	}

	// Retrieve Bob's funding outpoint.
	bobChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointBob)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	bobFundPoint := wire.OutPoint{
		Hash:  *bobChanTXID,
		Index: chanPointBob.OutputIndex,
	}

	// Next, we'll create Dave's node and open a private channel between him
	// and Carol with Carol being the funder.
	dave := net.NewNode(t.t, "Dave", nil)
	defer shutdownAndAssert(net, t, dave)

	net.ConnectNodes(t.t, carol, dave)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, carol)

	chanPointCarol := openChannelAndAssert(
		t, net, carol, dave,
		lntest.OpenChannelParams{
			Amt:     chanAmt,
			Private: true,
		},
	)

	err = carol.WaitForNetworkChannelOpen(chanPointCarol)
	if err != nil {
		t.Fatalf("carol didn't see the channel carol <-> dave before "+
			"timeout: %v", err)
	}
	err = dave.WaitForNetworkChannelOpen(chanPointCarol)
	if err != nil {
		t.Fatalf("dave didn't see the channel carol <-> dave before "+
			"timeout: %v", err)
	}
	err = dave.WaitForNetworkChannelOpen(chanPointBob)
	if err != nil {
		t.Fatalf("dave didn't see the channel bob <-> carol before "+
			"timeout: %v", err)
	}

	// Retrieve Carol's funding point.
	carolChanTXID, err := lnrpc.GetChanPointFundingTxid(chanPointCarol)
	if err != nil {
		t.Fatalf("unable to get txid: %v", err)
	}
	carolFundPoint := wire.OutPoint{
		Hash:  *carolChanTXID,
		Index: chanPointCarol.OutputIndex,
	}

	// Now that all the channels are set up according to the topology from
	// above, we can proceed to test payments. We'll create an invoice for
	// Dave of 20k satoshis and pay it with Alice. Since there is no public
	// route from Alice to Dave, we'll need to use the private channel
	// between Carol and Dave as a routing hint encoded in the invoice.
	const paymentAmt = 20000

	// Create the invoice for Dave.
	invoice := &lnrpc.Invoice{
		Memo:    "two hopz!",
		Value:   paymentAmt,
		Private: true,
	}

	ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
	resp, err := dave.AddInvoice(ctxt, invoice)
	if err != nil {
		t.Fatalf("unable to add invoice for dave: %v", err)
	}

	// Let Alice pay the invoice.
	payReqs := []string{resp.PaymentRequest}
	err = completePaymentRequests(
		net.Alice, net.Alice.RouterClient, payReqs, true,
	)
	if err != nil {
		t.Fatalf("unable to send payments from alice to dave: %v", err)
	}

	// When asserting the amount of satoshis moved, we'll factor in the
	// default base fee, as we didn't modify the fee structure when opening
	// the channels.
	const baseFee = 1

	// Dave should have received 20k satoshis from Carol.
	assertAmountPaid(t, "Carol(local) [private=>] Dave(remote)",
		dave, carolFundPoint, 0, paymentAmt)

	// Carol should have sent 20k satoshis to Dave.
	assertAmountPaid(t, "Carol(local) [private=>] Dave(remote)",
		carol, carolFundPoint, paymentAmt, 0)

	// Carol should have received 20k satoshis + fee for one hop from Bob.
	assertAmountPaid(t, "Bob(local) => Carol(remote)",
		carol, bobFundPoint, 0, paymentAmt+baseFee)

	// Bob should have sent 20k satoshis + fee for one hop to Carol.
	assertAmountPaid(t, "Bob(local) => Carol(remote)",
		net.Bob, bobFundPoint, paymentAmt+baseFee, 0)

	// Bob should have received 20k satoshis + fee for two hops from Alice.
	assertAmountPaid(t, "Alice(local) [private=>] Bob(remote)", net.Bob,
		aliceFundPoint, 0, paymentAmt+baseFee*2)

	// Alice should have sent 20k satoshis + fee for two hops to Bob.
	assertAmountPaid(t, "Alice(local) [private=>] Bob(remote)", net.Alice,
		aliceFundPoint, paymentAmt+baseFee*2, 0)

	// At this point, the payment was successful. We can now close all the
	// channels and shutdown the nodes created throughout this test.
	closeChannelAndAssert(t, net, net.Alice, chanPointAlice, false)
	closeChannelAndAssert(t, net, net.Bob, chanPointBob, false)
	closeChannelAndAssert(t, net, carol, chanPointCarol, false)
}

// computeFee calculates the payment fee as specified in BOLT07
func computeFee(baseFee, feeRate, amt lnwire.MilliAtom) lnwire.MilliAtom {
	return baseFee + amt*feeRate/1000000
}

// testQueryRoutes checks the response of queryroutes.
// We'll create the following network topology:
//
//	Alice --> Bob --> Carol --> Dave
//
// and query the daemon for routes from Alice to Dave.
func testQueryRoutes(net *lntest.NetworkHarness, t *harnessTest) {
	ctxb := context.Background()

	const chanAmt = dcrutil.Amount(100000)
	var networkChans []*lnrpc.ChannelPoint

	// Open a channel between Alice and Bob.
	chanPointAlice := openChannelAndAssert(
		t, net, net.Alice, net.Bob,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	networkChans = append(networkChans, chanPointAlice)

	// Create Carol and establish a channel from Bob.
	carol := net.NewNode(t.t, "Carol", nil)
	defer shutdownAndAssert(net, t, carol)

	net.ConnectNodes(t.t, carol, net.Bob)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, net.Bob)

	chanPointBob := openChannelAndAssert(
		t, net, net.Bob, carol,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	networkChans = append(networkChans, chanPointBob)

	// Create Dave and establish a channel from Carol.
	dave := net.NewNode(t.t, "Dave", nil)
	defer shutdownAndAssert(net, t, dave)

	net.ConnectNodes(t.t, dave, carol)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, carol)

	chanPointCarol := openChannelAndAssert(
		t, net, carol, dave,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)
	networkChans = append(networkChans, chanPointCarol)

	// Wait for all nodes to have seen all channels.
	nodes := []*lntest.HarnessNode{net.Alice, net.Bob, carol, dave}
	nodeNames := []string{"Alice", "Bob", "Carol", "Dave"}
	for _, chanPoint := range networkChans {
		for i, node := range nodes {
			txid, err := lnrpc.GetChanPointFundingTxid(chanPoint)
			if err != nil {
				t.Fatalf("unable to get txid: %v", err)
			}
			point := wire.OutPoint{
				Hash:  *txid,
				Index: chanPoint.OutputIndex,
			}

			err = node.WaitForNetworkChannelOpen(chanPoint)
			if err != nil {
				t.Fatalf("%s(%d): timeout waiting for "+
					"channel(%s) open: %v", nodeNames[i],
					node.NodeID, point, err)
			}
		}
	}

	// Query for routes to pay from Alice to Dave.
	const paymentAmt = 1000
	routesReq := &lnrpc.QueryRoutesRequest{
		PubKey: dave.PubKeyStr,
		Amt:    paymentAmt,
	}
	ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
	routesRes, err := net.Alice.QueryRoutes(ctxt, routesReq)
	if err != nil {
		t.Fatalf("unable to get route: %v", err)
	}

	const mSat = 1000
	feePerHopMSat := computeFee(1000, 1, paymentAmt*mSat)

	for i, route := range routesRes.Routes {
		expectedTotalFeesMSat :=
			lnwire.MilliAtom(len(route.Hops)-1) * feePerHopMSat
		expectedTotalAmtMSat := (paymentAmt * mSat) + expectedTotalFeesMSat

		if route.TotalFees != route.TotalFeesMAtoms/mSat { // nolint:staticcheck
			t.Fatalf("route %v: total fees %v (msat) does not "+
				"round down to %v (sat)",
				i, route.TotalFeesMAtoms, route.TotalFees) // nolint:staticcheck
		}
		if route.TotalFeesMAtoms != int64(expectedTotalFeesMSat) {
			t.Fatalf("route %v: total fees in msat expected %v got %v",
				i, expectedTotalFeesMSat, route.TotalFeesMAtoms)
		}

		if route.TotalAmt != route.TotalAmtMAtoms/mSat { // nolint:staticcheck
			t.Fatalf("route %v: total amt %v (msat) does not "+
				"round down to %v (sat)",
				i, route.TotalAmtMAtoms, route.TotalAmt) // nolint:staticcheck
		}
		if route.TotalAmtMAtoms != int64(expectedTotalAmtMSat) {
			t.Fatalf("route %v: total amt in msat expected %v got %v",
				i, expectedTotalAmtMSat, route.TotalAmtMAtoms)
		}

		// For all hops except the last, we check that fee equals feePerHop
		// and amount to forward deducts feePerHop on each hop.
		expectedAmtToForwardMSat := expectedTotalAmtMSat
		for j, hop := range route.Hops[:len(route.Hops)-1] {
			expectedAmtToForwardMSat -= feePerHopMSat

			if hop.Fee != hop.FeeMAtoms/mSat { // nolint:staticcheck
				t.Fatalf("route %v hop %v: fee %v (msat) does not "+
					"round down to %v (sat)",
					i, j, hop.FeeMAtoms, hop.Fee) // nolint:staticcheck
			}
			if hop.FeeMAtoms != int64(feePerHopMSat) {
				t.Fatalf("route %v hop %v: fee in msat expected %v got %v",
					i, j, feePerHopMSat, hop.FeeMAtoms)
			}

			if hop.AmtToForward != hop.AmtToForwardMAtoms/mSat { // nolint:staticcheck
				t.Fatalf("route %v hop %v: amt to forward %v (msat) does not "+
					"round down to %v (sat)",
					i, j, hop.AmtToForwardMAtoms, hop.AmtToForward) // nolint:staticcheck
			}
			if hop.AmtToForwardMAtoms != int64(expectedAmtToForwardMSat) {
				t.Fatalf("route %v hop %v: amt to forward in msat "+
					"expected %v got %v",
					i, j, expectedAmtToForwardMSat, hop.AmtToForwardMAtoms)
			}
		}
		// Last hop should have zero fee and amount to forward should equal
		// payment amount.
		hop := route.Hops[len(route.Hops)-1]

		if hop.Fee != 0 || hop.FeeMAtoms != 0 { // nolint:staticcheck
			t.Fatalf("route %v hop %v: fee expected 0 got %v (sat) %v (msat)",
				i, len(route.Hops)-1, hop.Fee, hop.FeeMAtoms) // nolint:staticcheck
		}

		if hop.AmtToForward != hop.AmtToForwardMAtoms/mSat { // nolint:staticcheck
			t.Fatalf("route %v hop %v: amt to forward %v (msat) does not "+
				"round down to %v (sat)",
				i, len(route.Hops)-1, hop.AmtToForwardMAtoms, hop.AmtToForward) // nolint:staticcheck
		}
		if hop.AmtToForwardMAtoms != paymentAmt*mSat {
			t.Fatalf("route %v hop %v: amt to forward in msat "+
				"expected %v got %v",
				i, len(route.Hops)-1, paymentAmt*mSat, hop.AmtToForwardMAtoms)
		}
	}

	// While we're here, we test updating mission control's config values
	// and assert that they are correctly updated and check that our mission
	// control import function updates appropriately.
	testMissionControlCfg(t.t, net.Alice)
	testMissionControlImport(
		t.t, net.Alice, net.Bob.PubKey[:], carol.PubKey[:],
	)

	// We clean up the test case by closing channels that were created for
	// the duration of the tests.
	closeChannelAndAssert(t, net, net.Alice, chanPointAlice, false)
	closeChannelAndAssert(t, net, net.Bob, chanPointBob, false)
	closeChannelAndAssert(t, net, carol, chanPointCarol, false)
}

// testMissionControlCfg tests getting and setting of a node's mission control
// config, resetting to the original values after testing so that no other
// tests are affected.
func testMissionControlCfg(t *testing.T, node *lntest.HarnessNode) {
	ctxb := context.Background()
	startCfg, err := node.RouterClient.GetMissionControlConfig(
		ctxb, &routerrpc.GetMissionControlConfigRequest{},
	)
	require.NoError(t, err)

	cfg := &routerrpc.MissionControlConfig{
		HalfLifeSeconds:             8000,
		HopProbability:              0.8,
		Weight:                      0.3,
		MaximumPaymentResults:       30,
		MinimumFailureRelaxInterval: 60,
	}

	_, err = node.RouterClient.SetMissionControlConfig(
		ctxb, &routerrpc.SetMissionControlConfigRequest{
			Config: cfg,
		},
	)
	require.NoError(t, err)

	resp, err := node.RouterClient.GetMissionControlConfig(
		ctxb, &routerrpc.GetMissionControlConfigRequest{},
	)
	require.NoError(t, err)
	require.True(t, proto.Equal(cfg, resp.Config))

	_, err = node.RouterClient.SetMissionControlConfig(
		ctxb, &routerrpc.SetMissionControlConfigRequest{
			Config: startCfg.Config,
		},
	)
	require.NoError(t, err)
}

// testMissionControlImport tests import of mission control results from an
// external source.
func testMissionControlImport(t *testing.T, node *lntest.HarnessNode,
	fromNode, toNode []byte) {

	ctxb := context.Background()

	// Reset mission control so that our query will return the default
	// probability for our first request.
	_, err := node.RouterClient.ResetMissionControl(
		ctxb, &routerrpc.ResetMissionControlRequest{},
	)
	require.NoError(t, err, "could not reset mission control")

	// Get our baseline probability for a 10 msat hop between our target
	// nodes.
	var amount int64 = 10
	probReq := &routerrpc.QueryProbabilityRequest{
		FromNode:  fromNode,
		ToNode:    toNode,
		AmtMAtoms: amount,
	}

	importHistory := &routerrpc.PairData{
		FailTime:      time.Now().Unix(),
		FailAmtMAtoms: amount,
	}

	// Assert that our history is not already equal to the value we want to
	// set. This should not happen because we have just cleared our state.
	resp1, err := node.RouterClient.QueryProbability(ctxb, probReq)
	require.NoError(t, err, "query probability failed")
	require.Zero(t, resp1.History.FailTime)
	require.Zero(t, resp1.History.FailAmtMAtoms)

	// Now, we import a single entry which tracks a failure of the amount
	// we want to query between our nodes.
	req := &routerrpc.XImportMissionControlRequest{
		Pairs: []*routerrpc.PairHistory{
			{
				NodeFrom: fromNode,
				NodeTo:   toNode,
				History:  importHistory,
			},
		},
	}

	_, err = node.RouterClient.XImportMissionControl(ctxb, req)
	require.NoError(t, err, "could not import config")

	resp2, err := node.RouterClient.QueryProbability(ctxb, probReq)
	require.NoError(t, err, "query probability failed")
	require.Equal(t, importHistory.FailTime, resp2.History.FailTime)
	require.Equal(t, importHistory.FailAmtMAtoms, resp2.History.FailAmtMAtoms)

	// Finally, check that we will fail if inconsistent sat/msat values are
	// set.
	importHistory.FailAmtAtoms = amount * 2
	_, err = node.RouterClient.XImportMissionControl(ctxb, req)
	require.Error(t, err, "mismatched import amounts succeeded")
}

// testRouteFeeCutoff tests that we are able to prevent querying routes and
// sending payments that incur a fee higher than the fee limit.
func testRouteFeeCutoff(net *lntest.NetworkHarness, t *harnessTest) {
	ctxb := context.Background()

	// For this test, we'll create the following topology:
	//
	//              --- Bob ---
	//            /             \
	// Alice ----                 ---- Dave
	//            \             /
	//              -- Carol --
	//
	// Alice will attempt to send payments to Dave that should not incur a
	// fee greater than the fee limit expressed as a percentage of the
	// amount and as a fixed amount of satoshis.
	const chanAmt = dcrutil.Amount(100000)

	// Open a channel between Alice and Bob.
	chanPointAliceBob := openChannelAndAssert(
		t, net, net.Alice, net.Bob,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)

	// Create Carol's node and open a channel between her and Alice with
	// Alice being the funder.
	carol := net.NewNode(t.t, "Carol", nil)
	defer shutdownAndAssert(net, t, carol)

	net.ConnectNodes(t.t, carol, net.Alice)
	net.SendCoins(t.t, dcrutil.AtomsPerCoin, carol)

	chanPointAliceCarol := openChannelAndAssert(
		t, net, net.Alice, carol,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)

	// Create Dave's node and open a channel between him and Bob with Bob
	// being the funder.
	dave := net.NewNode(t.t, "Dave", nil)
	defer shutdownAndAssert(net, t, dave)

	net.ConnectNodes(t.t, dave, net.Bob)
	chanPointBobDave := openChannelAndAssert(
		t, net, net.Bob, dave,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)

	// Open a channel between Carol and Dave.
	net.ConnectNodes(t.t, carol, dave)
	chanPointCarolDave := openChannelAndAssert(
		t, net, carol, dave,
		lntest.OpenChannelParams{
			Amt: chanAmt,
		},
	)

	// Now that all the channels were set up, we'll wait for all the nodes
	// to have seen all the channels.
	nodes := []*lntest.HarnessNode{net.Alice, net.Bob, carol, dave}
	nodeNames := []string{"alice", "bob", "carol", "dave"}
	networkChans := []*lnrpc.ChannelPoint{
		chanPointAliceBob, chanPointAliceCarol, chanPointBobDave,
		chanPointCarolDave,
	}
	for _, chanPoint := range networkChans {
		for i, node := range nodes {
			txid, err := lnrpc.GetChanPointFundingTxid(chanPoint)
			if err != nil {
				t.Fatalf("unable to get txid: %v", err)
			}
			outpoint := wire.OutPoint{
				Hash:  *txid,
				Index: chanPoint.OutputIndex,
			}

			err = node.WaitForNetworkChannelOpen(chanPoint)
			if err != nil {
				t.Fatalf("%s(%d) timed out waiting for "+
					"channel(%s) open: %v", nodeNames[i],
					node.NodeID, outpoint, err)
			}
		}
	}

	// The payments should only be successful across the route:
	//	Alice -> Bob -> Dave
	// Therefore, we'll update the fee policy on Carol's side for the
	// channel between her and Dave to invalidate the route:
	//	Alice -> Carol -> Dave
	baseFee := int64(10000)
	feeRate := int64(5)
	timeLockDelta := uint32(chainreg.DefaultDecredTimeLockDelta)
	maxHtlc := calculateMaxHtlc(chanAmt)

	expectedPolicy := &lnrpc.RoutingPolicy{
		FeeBaseMAtoms:      baseFee,
		FeeRateMilliMAtoms: testFeeBase * feeRate,
		TimeLockDelta:      timeLockDelta,
		MinHtlc:            1000, // default value
		MaxHtlcMAtoms:      maxHtlc,
	}

	updateFeeReq := &lnrpc.PolicyUpdateRequest{
		BaseFeeMAtoms: baseFee,
		FeeRate:       float64(feeRate),
		TimeLockDelta: timeLockDelta,
		MaxHtlcMAtoms: maxHtlc,
		Scope: &lnrpc.PolicyUpdateRequest_ChanPoint{
			ChanPoint: chanPointCarolDave,
		},
	}
	ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
	if _, err := carol.UpdateChannelPolicy(ctxt, updateFeeReq); err != nil {
		t.Fatalf("unable to update chan policy: %v", err)
	}

	// Wait for Alice to receive the channel update from Carol.
	assertChannelPolicyUpdate(
		t.t, net.Alice, carol.PubKeyStr,
		expectedPolicy, chanPointCarolDave, false,
	)

	// We'll also need the channel IDs for Bob's channels in order to
	// confirm the route of the payments.
	listReq := &lnrpc.ListChannelsRequest{}
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	listResp, err := net.Bob.ListChannels(ctxt, listReq)
	if err != nil {
		t.Fatalf("unable to retrieve bob's channels: %v", err)
	}

	var aliceBobChanID, bobDaveChanID uint64
	for _, channel := range listResp.Channels {
		switch channel.RemotePubkey {
		case net.Alice.PubKeyStr:
			aliceBobChanID = channel.ChanId
		case dave.PubKeyStr:
			bobDaveChanID = channel.ChanId
		}
	}

	if aliceBobChanID == 0 {
		t.Fatalf("channel between alice and bob not found")
	}
	if bobDaveChanID == 0 {
		t.Fatalf("channel between bob and dave not found")
	}
	hopChanIDs := []uint64{aliceBobChanID, bobDaveChanID}

	// checkRoute is a helper closure to ensure the route contains the
	// correct intermediate hops.
	checkRoute := func(route *lnrpc.Route) {
		if len(route.Hops) != 2 {
			t.Fatalf("expected two hops, got %d", len(route.Hops))
		}

		for i, hop := range route.Hops {
			if hop.ChanId != hopChanIDs[i] {
				t.Fatalf("expected chan id %d, got %d",
					hopChanIDs[i], hop.ChanId)
			}
		}
	}

	// We'll be attempting to send two payments from Alice to Dave. One will
	// have a fee cutoff expressed as a percentage of the amount and the
	// other will have it expressed as a fixed amount of satoshis.
	const paymentAmt = 100
	carolFee := computeFee(lnwire.MilliAtom(baseFee), 1, paymentAmt)

	// testFeeCutoff is a helper closure that will ensure the different
	// types of fee limits work as intended when querying routes and sending
	// payments.
	testFeeCutoff := func(feeLimit *lnrpc.FeeLimit) {
		queryRoutesReq := &lnrpc.QueryRoutesRequest{
			PubKey:   dave.PubKeyStr,
			Amt:      paymentAmt,
			FeeLimit: feeLimit,
		}
		ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
		routesResp, err := net.Alice.QueryRoutes(ctxt, queryRoutesReq)
		if err != nil {
			t.Fatalf("unable to get routes: %v", err)
		}

		checkRoute(routesResp.Routes[0])

		invoice := &lnrpc.Invoice{Value: paymentAmt}
		ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
		invoiceResp, err := dave.AddInvoice(ctxt, invoice)
		if err != nil {
			t.Fatalf("unable to create invoice: %v", err)
		}

		sendReq := &routerrpc.SendPaymentRequest{
			PaymentRequest: invoiceResp.PaymentRequest,
			TimeoutSeconds: 60,
			FeeLimitMAtoms: noFeeLimitMAtoms,
		}
		switch limit := feeLimit.Limit.(type) {
		case *lnrpc.FeeLimit_Fixed:
			sendReq.FeeLimitMAtoms = 1000 * limit.Fixed
		case *lnrpc.FeeLimit_Percent:
			sendReq.FeeLimitMAtoms = 1000 * paymentAmt * limit.Percent / 100
		}

		result := sendAndAssertSuccess(t, net.Alice, sendReq)

		checkRoute(result.Htlcs[0].Route)
	}

	// We'll start off using percentages first. Since the fee along the
	// route using Carol as an intermediate hop is 10% of the payment's
	// amount, we'll use a lower percentage in order to invalid that route.
	feeLimitPercent := &lnrpc.FeeLimit{
		Limit: &lnrpc.FeeLimit_Percent{
			Percent: baseFee/1000 - 1,
		},
	}
	testFeeCutoff(feeLimitPercent)

	// Now we'll test using fixed fee limit amounts. Since we computed the
	// fee for the route using Carol as an intermediate hop earlier, we can
	// use a smaller value in order to invalidate that route.
	feeLimitFixed := &lnrpc.FeeLimit{
		Limit: &lnrpc.FeeLimit_Fixed{
			Fixed: int64(carolFee.ToAtoms()) - 1,
		},
	}
	testFeeCutoff(feeLimitFixed)

	// Once we're done, close the channels and shut down the nodes created
	// throughout this test.
	closeChannelAndAssert(t, net, net.Alice, chanPointAliceBob, false)
	closeChannelAndAssert(t, net, net.Alice, chanPointAliceCarol, false)
	closeChannelAndAssert(t, net, net.Bob, chanPointBobDave, false)
	closeChannelAndAssert(t, net, carol, chanPointCarolDave, false)
}