lntest/itest: add coverage for querying routes to blinded paths

itest/list_on_test.go

@@ -546,4 +546,8 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "update pending open channels",
 		TestFunc: testUpdateOnPendingOpenChannels,
 	},
+	{
+		Name:     "query blinded route",
+		TestFunc: testQueryBlindedRoutes,
+	},
 }

itest/lnd_route_blinding.go

@@ -0,0 +1,273 @@
+package itest
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcutil"
+	"github.com/lightningnetwork/lnd/chainreg"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
+	"github.com/lightningnetwork/lnd/lntest"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// testQueryBlindedRoutes tests querying routes to blinded routes. To do this,
+// it sets up a nework of Alice - Bob - Carol and creates a mock blinded route
+// that uses Carol as the introduction node (plus dummy hops to cover multiple
+// hops). The test simply asserts that the structure of the route is as
+// expected.
+func testQueryBlindedRoutes(ht *lntest.HarnessTest) {
+	var (
+		// Convenience aliases.
+		alice = ht.Alice
+		bob   = ht.Bob
+	)
+
+	// Setup a two hop channel network: Alice -- Bob -- Carol.
+	// We set our proportional fee for these channels to zero, so that
+	// our calculations are easier. This is okay, because we're not testing
+	// the basic mechanics of pathfinding in this test.
+	chanAmt := btcutil.Amount(100000)
+	chanPointAliceBob := ht.OpenChannel(
+		alice, bob, lntest.OpenChannelParams{
+			Amt:        chanAmt,
+			BaseFee:    10000,
+			FeeRate:    0,
+			UseBaseFee: true,
+			UseFeeRate: true,
+		},
+	)
+
+	carol := ht.NewNode("Carol", nil)
+	ht.EnsureConnected(bob, carol)
+
+	var bobCarolBase uint64 = 2000
+	chanPointBobCarol := ht.OpenChannel(
+		bob, carol, lntest.OpenChannelParams{
+			Amt:        chanAmt,
+			BaseFee:    bobCarolBase,
+			FeeRate:    0,
+			UseBaseFee: true,
+			UseFeeRate: true,
+		},
+	)
+
+	// Wait for Alice to see Bob/Carol's channel because she'll need it for
+	// pathfinding.
+	ht.AssertTopologyChannelOpen(alice, chanPointBobCarol)
+
+	// Lookup full channel info so that we have channel ids for our route.
+	aliceBobChan := ht.GetChannelByChanPoint(alice, chanPointAliceBob)
+	bobCarolChan := ht.GetChannelByChanPoint(bob, chanPointBobCarol)
+
+	// Sanity check that bob's fee is as expected.
+	chanInfoReq := &lnrpc.ChanInfoRequest{
+		ChanId: bobCarolChan.ChanId,
+	}
+
+	bobCarolInfo := bob.RPC.GetChanInfo(chanInfoReq)
+
+	// Our test relies on knowing the fee rate for bob - carol to set the
+	// fees we expect for our route. Perform a quick sanity check that our
+	// policy is as expected.
+	var policy *lnrpc.RoutingPolicy
+	if bobCarolInfo.Node1Pub == bob.PubKeyStr {
+		policy = bobCarolInfo.Node1Policy
+	} else {
+		policy = bobCarolInfo.Node2Policy
+	}
+	require.Equal(ht, bobCarolBase, uint64(policy.FeeBaseMsat), "base fee")
+	require.EqualValues(ht, 0, policy.FeeRateMilliMsat, "fee rate")
+
+	// We'll also need the current block height to calculate our locktimes.
+	info := alice.RPC.GetInfo()
+
+	// Since we created channels with default parameters, we can assume
+	// that all of our channels have the default cltv delta.
+	bobCarolDelta := uint32(chainreg.DefaultBitcoinTimeLockDelta)
+
+	// Create arbitrary pubkeys for use in our blinded route. They're not
+	// actually used functionally in this test, so we can just make them up.
+	var (
+		_, blindingPoint = btcec.PrivKeyFromBytes([]byte{1})
+		_, carolBlinded  = btcec.PrivKeyFromBytes([]byte{2})
+		_, blindedHop1   = btcec.PrivKeyFromBytes([]byte{3})
+		_, blindedHop2   = btcec.PrivKeyFromBytes([]byte{4})
+
+		encryptedDataCarol = []byte{1, 2, 3}
+		encryptedData1     = []byte{4, 5, 6}
+		encryptedData2     = []byte{7, 8, 9}
+
+		blindingBytes     = blindingPoint.SerializeCompressed()
+		carolBlindedBytes = carolBlinded.SerializeCompressed()
+		blinded1Bytes     = blindedHop1.SerializeCompressed()
+		blinded2Bytes     = blindedHop2.SerializeCompressed()
+	)
+
+	// Now we create a blinded route which uses carol as an introduction
+	// node followed by two dummy hops (the arbitrary pubkeys in our
+	// blinded route above:
+	// Carol --- B1 --- B2
+	route := &lnrpc.BlindedPath{
+		IntroductionNode: carol.PubKey[:],
+		BlindingPoint:    blindingBytes,
+		BlindedHops: []*lnrpc.BlindedHop{
+			{
+				// The first hop in the blinded route is
+				// expected to be the introduction node.
+				BlindedNode:   carolBlindedBytes,
+				EncryptedData: encryptedDataCarol,
+			},
+			{
+				BlindedNode:   blinded1Bytes,
+				EncryptedData: encryptedData1,
+			},
+			{
+				BlindedNode:   blinded2Bytes,
+				EncryptedData: encryptedData2,
+			},
+		},
+	}
+
+	// Create a blinded payment that has aggregate cltv and fee params
+	// for our route.
+	var (
+		blindedBaseFee   uint64 = 1500
+		blindedCltvDelta uint32 = 125
+	)
+
+	blindedPayment := &lnrpc.BlindedPaymentPath{
+		BlindedPath:    route,
+		BaseFeeMsat:    blindedBaseFee,
+		TotalCltvDelta: blindedCltvDelta,
+	}
+
+	// Query for a route to the blinded path constructed above.
+	var paymentAmt int64 = 100_000
+
+	req := &lnrpc.QueryRoutesRequest{
+		AmtMsat: paymentAmt,
+		BlindedPaymentPaths: []*lnrpc.BlindedPaymentPath{
+			blindedPayment,
+		},
+	}
+
+	resp := alice.RPC.QueryRoutes(req)
+	require.Len(ht, resp.Routes, 1)
+
+	// Payment amount and cltv will be included for the bob/carol edge
+	// (because we apply on the outgoing hop), and the blinded portion of
+	// the route.
+	totalFee := bobCarolBase + blindedBaseFee
+	totalAmt := uint64(paymentAmt) + totalFee
+	totalCltv := info.BlockHeight + bobCarolDelta + blindedCltvDelta
+
+	// Alice -> Bob
+	//   Forward: total - bob carol fees
+	//   Expiry: total - bob carol delta
+	//
+	// Bob -> Carol
+	//  Forward: 101500 (total + blinded fees)
+	//  Expiry: Height + blinded cltv delta
+	//  Encrypted Data: enc_carol
+	//
+	// Carol -> Blinded 1
+	//  Forward/ Expiry: 0
+	//  Encrypted Data: enc_1
+	//
+	// Blinded 1 -> Blinded 2
+	//  Forward/ Expiry: Height
+	//  Encrypted Data: enc_2
+	hop0Amount := int64(totalAmt - bobCarolBase)
+	hop0Expiry := totalCltv - bobCarolDelta
+	finalHopExpiry := totalCltv - bobCarolDelta - blindedCltvDelta
+
+	expectedRoute := &lnrpc.Route{
+		TotalTimeLock: totalCltv,
+		TotalAmtMsat:  int64(totalAmt),
+		TotalFeesMsat: int64(totalFee),
+		Hops: []*lnrpc.Hop{
+			{
+				ChanId:           aliceBobChan.ChanId,
+				Expiry:           hop0Expiry,
+				AmtToForwardMsat: hop0Amount,
+				FeeMsat:          int64(bobCarolBase),
+				PubKey:           bob.PubKeyStr,
+			},
+			{
+				ChanId:        bobCarolChan.ChanId,
+				PubKey:        carol.PubKeyStr,
+				BlindingPoint: blindingBytes,
+				FeeMsat:       int64(blindedBaseFee),
+				EncryptedData: encryptedDataCarol,
+			},
+			{
+				PubKey: hex.EncodeToString(
+					blinded1Bytes,
+				),
+				EncryptedData: encryptedData1,
+			},
+			{
+				PubKey: hex.EncodeToString(
+					blinded2Bytes,
+				),
+				AmtToForwardMsat: paymentAmt,
+				Expiry:           finalHopExpiry,
+				EncryptedData:    encryptedData2,
+				TotalAmtMsat:     uint64(paymentAmt),
+			},
+		},
+	}
+
+	r := resp.Routes[0]
+	assert.Equal(ht, expectedRoute.TotalTimeLock, r.TotalTimeLock)
+	assert.Equal(ht, expectedRoute.TotalAmtMsat, r.TotalAmtMsat)
+	assert.Equal(ht, expectedRoute.TotalFeesMsat, r.TotalFeesMsat)
+
+	assert.Equal(ht, len(expectedRoute.Hops), len(r.Hops))
+	for i, hop := range expectedRoute.Hops {
+		assert.Equal(ht, hop.PubKey, r.Hops[i].PubKey,
+			"hop: %v pubkey", i)
+
+		assert.Equal(ht, hop.ChanId, r.Hops[i].ChanId,
+			"hop: %v chan id", i)
+
+		assert.Equal(ht, hop.Expiry, r.Hops[i].Expiry,
+			"hop: %v expiry", i)
+
+		assert.Equal(ht, hop.AmtToForwardMsat,
+			r.Hops[i].AmtToForwardMsat, "hop: %v forward", i)
+
+		assert.Equal(ht, hop.FeeMsat, r.Hops[i].FeeMsat,
+			"hop: %v fee", i)
+
+		assert.Equal(ht, hop.BlindingPoint, r.Hops[i].BlindingPoint,
+			"hop: %v blinding point", i)
+
+		assert.Equal(ht, hop.EncryptedData, r.Hops[i].EncryptedData,
+			"hop: %v encrypted data", i)
+	}
+
+	// Dispatch a payment to our blinded route.
+	preimage := [33]byte{1, 2, 3}
+	hash := sha256.Sum256(preimage[:])
+
+	sendReq := &routerrpc.SendToRouteRequest{
+		PaymentHash: hash[:],
+		Route:       r,
+	}
+
+	htlcAttempt := alice.RPC.SendToRouteV2(sendReq)
+
+	// Since Carol doesn't understand blinded routes, we expect her to fail
+	// the payment because the onion payload is invalid (missing amount to
+	// forward).
+	require.NotNil(ht, htlcAttempt.Failure)
+	require.Equal(ht, uint32(2), htlcAttempt.Failure.FailureSourceIndex)
+
+	ht.CloseChannel(alice, chanPointAliceBob)
+	ht.CloseChannel(bob, chanPointBobCarol)
+}