package routing import ( "testing" "github.com/btcsuite/btcutil" "github.com/lightningnetwork/lnd/lnwire" ) // TestProbabilityExtrapolation tests that probabilities for tried channels are // extrapolated to untried channels. This is a way to improve pathfinding // success by steering away from bad nodes. func TestProbabilityExtrapolation(t *testing.T) { ctx := newIntegratedRoutingContext(t) // Create the following network of nodes: // source -> expensiveNode (charges routing fee) -> target // source -> intermediate1 (free routing) -> intermediate(1-10) (free routing) -> target g := ctx.graph const expensiveNodeID = 3 expensiveNode := newMockNode(expensiveNodeID) expensiveNode.baseFee = 10000 g.addNode(expensiveNode) g.addChannel(100, sourceNodeID, expensiveNodeID, 100000) g.addChannel(101, targetNodeID, expensiveNodeID, 100000) const intermediate1NodeID = 4 intermediate1 := newMockNode(intermediate1NodeID) g.addNode(intermediate1) g.addChannel(102, sourceNodeID, intermediate1NodeID, 100000) for i := 0; i < 10; i++ { imNodeID := byte(10 + i) imNode := newMockNode(imNodeID) g.addNode(imNode) g.addChannel(uint64(200+i), imNodeID, targetNodeID, 100000) g.addChannel(uint64(300+i), imNodeID, intermediate1NodeID, 100000) // The channels from intermediate1 all have insufficient balance. g.nodes[intermediate1.pubkey].channels[imNode.pubkey].balance = 0 } // It is expected that pathfinding will try to explore the routes via // intermediate1 first, because those are free. But as failures happen, // the node probability of intermediate1 will go down in favor of the // paid route via expensiveNode. // // The exact number of attempts required is dependent on mission control // config. For this test, it would have been enough to only assert that // we are not trying all routes via intermediate1. However, we do assert // a specific number of attempts to safe-guard against accidental // modifications anywhere in the chain of components that is involved in // this test. attempts, err := ctx.testPayment(1) if err != nil { t.Fatalf("payment failed: %v", err) } if len(attempts) != 5 { t.Fatalf("expected 5 attempts, but needed %v", len(attempts)) } // If we use a static value for the node probability (no extrapolation // of data from other channels), all ten bad channels will be tried // first before switching to the paid channel. ctx.mcCfg.AprioriWeight = 1 attempts, err = ctx.testPayment(1) if err != nil { t.Fatalf("payment failed: %v", err) } if len(attempts) != 11 { t.Fatalf("expected 11 attempts, but needed %v", len(attempts)) } } type mppSendTestCase struct { name string amt btcutil.Amount expectedAttempts int // expectedSuccesses is a list of htlcs that made it to the receiver, // regardless of whether the final set became complete or not. expectedSuccesses []expectedHtlcSuccess graph func(g *mockGraph) expectedFailure bool maxHtlcs uint32 } const ( chanSourceIm1 = 13 chanIm1Target = 32 chanSourceIm2 = 14 chanIm2Target = 42 ) func onePathGraph(g *mockGraph) { // Create the following network of nodes: // source -> intermediate1 -> target const im1NodeID = 3 intermediate1 := newMockNode(im1NodeID) g.addNode(intermediate1) g.addChannel(chanSourceIm1, sourceNodeID, im1NodeID, 200000) g.addChannel(chanIm1Target, targetNodeID, im1NodeID, 100000) } func twoPathGraph(g *mockGraph) { // Create the following network of nodes: // source -> intermediate1 -> target // source -> intermediate2 -> target const im1NodeID = 3 intermediate1 := newMockNode(im1NodeID) g.addNode(intermediate1) const im2NodeID = 4 intermediate2 := newMockNode(im2NodeID) g.addNode(intermediate2) g.addChannel(chanSourceIm1, sourceNodeID, im1NodeID, 200000) g.addChannel(chanSourceIm2, sourceNodeID, im2NodeID, 200000) g.addChannel(chanIm1Target, targetNodeID, im1NodeID, 100000) g.addChannel(chanIm2Target, targetNodeID, im2NodeID, 100000) } var mppTestCases = []mppSendTestCase{ // Test a two-path graph with sufficient liquidity. It is expected that // pathfinding will try first try to send the full amount via the two // available routes. When that fails, it will half the amount to 35k sat // and retry. That attempt reaches the target successfully. Then the // same route is tried again. Because the channel only had 50k sat, it // will fail. Finally the second route is tried for 35k and it succeeds // too. Mpp payment complete. { name: "sufficient inbound", graph: twoPathGraph, amt: 70000, expectedAttempts: 5, expectedSuccesses: []expectedHtlcSuccess{ { amt: 35000, chans: []uint64{chanSourceIm1, chanIm1Target}, }, { amt: 35000, chans: []uint64{chanSourceIm2, chanIm2Target}, }, }, maxHtlcs: 1000, }, // Test that a cap on the max htlcs makes it impossible to pay. { name: "no splitting", graph: twoPathGraph, amt: 70000, expectedAttempts: 2, expectedSuccesses: []expectedHtlcSuccess{}, expectedFailure: true, maxHtlcs: 1, }, // Test that an attempt is made to split the payment in multiple parts // that all use the same route if the full amount cannot be sent in a // single htlc. The sender is effectively probing the receiver's // incoming channel to see if it has sufficient balance. In this test // case, the endeavour fails. { name: "one path split", graph: onePathGraph, amt: 70000, expectedAttempts: 7, expectedSuccesses: []expectedHtlcSuccess{ { amt: 35000, chans: []uint64{chanSourceIm1, chanIm1Target}, }, { amt: 8750, chans: []uint64{chanSourceIm1, chanIm1Target}, }, }, expectedFailure: true, maxHtlcs: 1000, }, } // TestMppSend tests that a payment can be completed using multiple shards. func TestMppSend(t *testing.T) { for _, testCase := range mppTestCases { testCase := testCase t.Run(testCase.name, func(t *testing.T) { testMppSend(t, &testCase) }) } } func testMppSend(t *testing.T, testCase *mppSendTestCase) { ctx := newIntegratedRoutingContext(t) g := ctx.graph testCase.graph(g) ctx.amt = lnwire.NewMSatFromSatoshis(testCase.amt) attempts, err := ctx.testPayment(testCase.maxHtlcs) switch { case err == nil && testCase.expectedFailure: t.Fatal("expected payment to fail") case err != nil && !testCase.expectedFailure: t.Fatal("expected payment to succeed") } if len(attempts) != testCase.expectedAttempts { t.Fatalf("expected %v attempts, but needed %v", testCase.expectedAttempts, len(attempts), ) } assertSuccessAttempts(t, attempts, testCase.expectedSuccesses) } // expectedHtlcSuccess describes an expected successful htlc attempt. type expectedHtlcSuccess struct { amt btcutil.Amount chans []uint64 } // equals matches the expectation with an actual attempt. func (e *expectedHtlcSuccess) equals(a htlcAttempt) bool { if a.route.TotalAmount != lnwire.NewMSatFromSatoshis(e.amt) { return false } if len(a.route.Hops) != len(e.chans) { return false } for i, h := range a.route.Hops { if h.ChannelID != e.chans[i] { return false } } return true } // assertSuccessAttempts asserts that the set of successful htlc attempts // matches the given expectation. func assertSuccessAttempts(t *testing.T, attempts []htlcAttempt, expected []expectedHtlcSuccess) { successCount := 0 loop: for _, a := range attempts { if !a.success { continue } successCount++ for _, exp := range expected { if exp.equals(a) { continue loop } } t.Fatalf("htlc success %v not found", a) } if successCount != len(expected) { t.Fatalf("expected %v successful htlcs, but got %v", expected, successCount) } }