package itest import ( "context" "time" "github.com/btcsuite/btcd/wire" "github.com/btcsuite/btcutil" "github.com/lightningnetwork/lnd/chainreg" "github.com/lightningnetwork/lnd/lnrpc" "github.com/lightningnetwork/lnd/lnrpc/routerrpc" "github.com/lightningnetwork/lnd/lntest" ) func testMultiHopPayments(net *lntest.NetworkHarness, t *harnessTest) { ctxb := context.Background() const chanAmt = btcutil.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. ctxt, _ := context.WithTimeout(ctxb, channelOpenTimeout) chanPointAlice := openChannelAndAssert( ctxt, t, net, 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, } // As preliminary setup, we'll create two new nodes: Carol and Dave, // such that we now have a 4 node, 3 channel topology. Dave will make a // channel with Alice, and Carol with Dave. After this setup, the // network topology should now look like: // Carol -> Dave -> Alice -> Bob // // First, we'll create Dave and establish a channel to Alice. Dave will // be running an older node that requires the legacy onion payload. daveArgs := []string{"--protocol.legacy.onion"} dave := net.NewNode(t.t, "Dave", daveArgs) defer shutdownAndAssert(net, t, dave) ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) net.ConnectNodes(ctxt, t.t, dave, net.Alice) ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) net.SendCoins(ctxt, t.t, btcutil.SatoshiPerBitcoin, dave) ctxt, _ = context.WithTimeout(ctxb, channelOpenTimeout) chanPointDave := openChannelAndAssert( ctxt, 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 to from her to // Dave. carol := net.NewNode(t.t, "Carol", nil) defer shutdownAndAssert(net, t, carol) ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) net.ConnectNodes(ctxt, t.t, carol, dave) ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) net.SendCoins(ctxt, t.t, btcutil.SatoshiPerBitcoin, carol) ctxt, _ = context.WithTimeout(ctxb, channelOpenTimeout) chanPointCarol := openChannelAndAssert( ctxt, 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{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, } ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) err = node.WaitForNetworkChannelOpen(ctxt, 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 Bob, which expect a payment from Carol for 1k // satoshis with a different preimage each time. const numPayments = 5 const paymentAmt = 1000 payReqs, _, _, err := createPayReqs( net.Bob, paymentAmt, numPayments, ) if err != nil { t.Fatalf("unable to create pay reqs: %v", err) } // We'll wait for all parties to recognize the new channels within the // network. ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) err = dave.WaitForNetworkChannelOpen(ctxt, chanPointDave) if err != nil { t.Fatalf("dave didn't advertise his channel: %v", err) } ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) err = carol.WaitForNetworkChannelOpen(ctxt, chanPointCarol) if err != nil { t.Fatalf("carol didn't advertise her channel in time: %v", err) } time.Sleep(time.Millisecond * 50) // Set the fee policies of the Alice -> Bob and the Dave -> Alice // channel edges to relatively large non default values. This makes it // possible to pick up more subtle fee calculation errors. maxHtlc := calculateMaxHtlc(chanAmt) const aliceBaseFeeSat = 1 const aliceFeeRatePPM = 100000 updateChannelPolicy( t, net.Alice, chanPointAlice, aliceBaseFeeSat*1000, aliceFeeRatePPM, chainreg.DefaultBitcoinTimeLockDelta, maxHtlc, carol, ) const daveBaseFeeSat = 5 const daveFeeRatePPM = 150000 updateChannelPolicy( t, dave, chanPointDave, daveBaseFeeSat*1000, daveFeeRatePPM, chainreg.DefaultBitcoinTimeLockDelta, maxHtlc, carol, ) // Before we start sending payments, subscribe to htlc events for each // node. ctxt, cancel := context.WithTimeout(ctxb, defaultTimeout) defer cancel() aliceEvents, err := net.Alice.RouterClient.SubscribeHtlcEvents( ctxt, &routerrpc.SubscribeHtlcEventsRequest{}, ) if err != nil { t.Fatalf("could not subscribe events: %v", err) } bobEvents, err := net.Bob.RouterClient.SubscribeHtlcEvents( ctxt, &routerrpc.SubscribeHtlcEventsRequest{}, ) if err != nil { t.Fatalf("could not subscribe events: %v", err) } carolEvents, err := carol.RouterClient.SubscribeHtlcEvents( ctxt, &routerrpc.SubscribeHtlcEventsRequest{}, ) if err != nil { t.Fatalf("could not subscribe events: %v", err) } daveEvents, err := dave.RouterClient.SubscribeHtlcEvents( ctxt, &routerrpc.SubscribeHtlcEventsRequest{}, ) if err != nil { t.Fatalf("could not subscribe events: %v", err) } // Using Carol as the source, pay to the 5 invoices from Bob created // above. ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) err = completePaymentRequests( ctxt, carol, carol.RouterClient, payReqs, true, ) if err != nil { t.Fatalf("unable to send payments: %v", err) } // At this point all the channels within our proto network should be // shifted by 5k satoshis in the direction of Bob, 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->David->Alice->Bob, order is Bob, // Alice, David, Carol. // The final node bob expects to get paid five times 1000 sat. expectedAmountPaidAtoB := int64(numPayments * paymentAmt) assertAmountPaid(t, "Alice(local) => Bob(remote)", net.Bob, aliceFundPoint, int64(0), expectedAmountPaidAtoB) assertAmountPaid(t, "Alice(local) => Bob(remote)", net.Alice, aliceFundPoint, expectedAmountPaidAtoB, int64(0)) // To forward a payment of 1000 sat, Alice is charging a fee of // 1 sat + 10% = 101 sat. const aliceFeePerPayment = aliceBaseFeeSat + (paymentAmt * aliceFeeRatePPM / 1_000_000) const expectedFeeAlice = numPayments * aliceFeePerPayment // Dave needs to pay what Alice pays plus Alice's fee. expectedAmountPaidDtoA := expectedAmountPaidAtoB + expectedFeeAlice assertAmountPaid(t, "Dave(local) => Alice(remote)", net.Alice, daveFundPoint, int64(0), expectedAmountPaidDtoA) assertAmountPaid(t, "Dave(local) => Alice(remote)", dave, daveFundPoint, expectedAmountPaidDtoA, int64(0)) // To forward a payment of 1101 sat, Dave is charging a fee of // 5 sat + 15% = 170.15 sat. This is rounded down in rpcserver to 170. const davePaymentAmt = paymentAmt + aliceFeePerPayment const daveFeePerPayment = daveBaseFeeSat + (davePaymentAmt * daveFeeRatePPM / 1_000_000) const expectedFeeDave = numPayments * daveFeePerPayment // Carol needs to pay what Dave pays plus Dave's fee. expectedAmountPaidCtoD := expectedAmountPaidDtoA + expectedFeeDave assertAmountPaid(t, "Carol(local) => Dave(remote)", dave, carolFundPoint, int64(0), expectedAmountPaidCtoD) assertAmountPaid(t, "Carol(local) => Dave(remote)", carol, carolFundPoint, expectedAmountPaidCtoD, int64(0)) // Now that we know all the balances have been settled out properly, // we'll ensure that our internal record keeping for completed circuits // was properly updated. // First, check that the FeeReport response shows the proper fees // accrued over each time range. Dave should've earned 170 satoshi for // each of the forwarded payments. ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) feeReport, err := dave.FeeReport(ctxt, &lnrpc.FeeReportRequest{}) if err != nil { t.Fatalf("unable to query for fee report: %v", err) } if feeReport.DayFeeSum != uint64(expectedFeeDave) { t.Fatalf("fee mismatch: expected %v, got %v", expectedFeeDave, feeReport.DayFeeSum) } if feeReport.WeekFeeSum != uint64(expectedFeeDave) { t.Fatalf("fee mismatch: expected %v, got %v", expectedFeeDave, feeReport.WeekFeeSum) } if feeReport.MonthFeeSum != uint64(expectedFeeDave) { t.Fatalf("fee mismatch: expected %v, got %v", expectedFeeDave, feeReport.MonthFeeSum) } // Next, ensure that if we issue the vanilla query for the forwarding // history, it returns 5 values, and each entry is formatted properly. ctxt, _ = context.WithTimeout(ctxb, defaultTimeout) fwdingHistory, err := dave.ForwardingHistory( ctxt, &lnrpc.ForwardingHistoryRequest{}, ) if err != nil { t.Fatalf("unable to query for fee report: %v", err) } if len(fwdingHistory.ForwardingEvents) != numPayments { t.Fatalf("wrong number of forwarding event: expected %v, "+ "got %v", numPayments, len(fwdingHistory.ForwardingEvents)) } expectedForwardingFee := uint64(expectedFeeDave / numPayments) for _, event := range fwdingHistory.ForwardingEvents { // Each event should show a fee of 170 satoshi. if event.Fee != expectedForwardingFee { t.Fatalf("fee mismatch: expected %v, got %v", expectedForwardingFee, event.Fee) } } // We expect Carol to have successful forwards and settles for // her sends. assertHtlcEvents( t, numPayments, 0, numPayments, routerrpc.HtlcEvent_SEND, carolEvents, ) // Dave and Alice should both have forwards and settles for // their role as forwarding nodes. assertHtlcEvents( t, numPayments, 0, numPayments, routerrpc.HtlcEvent_FORWARD, daveEvents, ) assertHtlcEvents( t, numPayments, 0, numPayments, routerrpc.HtlcEvent_FORWARD, aliceEvents, ) // Bob should only have settle events for his receives. assertHtlcEvents( t, 0, 0, numPayments, routerrpc.HtlcEvent_RECEIVE, bobEvents, ) ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout) closeChannelAndAssert(ctxt, t, net, net.Alice, chanPointAlice, false) ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout) closeChannelAndAssert(ctxt, t, net, dave, chanPointDave, false) ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout) closeChannelAndAssert(ctxt, t, net, carol, chanPointCarol, false) } // assertHtlcEvents consumes events from a client and ensures that they are of // the expected type and contain the expected number of forwards, forward // failures and settles. func assertHtlcEvents(t *harnessTest, fwdCount, fwdFailCount, settleCount int, userType routerrpc.HtlcEvent_EventType, client routerrpc.Router_SubscribeHtlcEventsClient) { var forwards, forwardFails, settles int numEvents := fwdCount + fwdFailCount + settleCount for i := 0; i < numEvents; i++ { event := assertEventAndType(t, userType, client) switch event.Event.(type) { case *routerrpc.HtlcEvent_ForwardEvent: forwards++ case *routerrpc.HtlcEvent_ForwardFailEvent: forwardFails++ case *routerrpc.HtlcEvent_SettleEvent: settles++ default: t.Fatalf("unexpected event: %T", event.Event) } } if forwards != fwdCount { t.Fatalf("expected: %v forwards, got: %v", fwdCount, forwards) } if forwardFails != fwdFailCount { t.Fatalf("expected: %v forward fails, got: %v", fwdFailCount, forwardFails) } if settles != settleCount { t.Fatalf("expected: %v settles, got: %v", settleCount, settles) } } // assertEventAndType reads an event from the stream provided and ensures that // it is associated with the correct user related type - a user initiated send, // a receive to our node or a forward through our node. Note that this event // type is different from the htlc event type (forward, link failure etc). func assertEventAndType(t *harnessTest, eventType routerrpc.HtlcEvent_EventType, client routerrpc.Router_SubscribeHtlcEventsClient) *routerrpc.HtlcEvent { event, err := client.Recv() if err != nil { t.Fatalf("could not get event") } if event.EventType != eventType { t.Fatalf("expected: %v, got: %v", eventType, event.EventType) } return event }