Add multiverse RPC proof courier (#473)

* tapfreighter: fix proof transition state doc

* rpc: move MarshalAsset function to new file taprpc/marshal.go

This refactor allows us to avoid an import cycle when the RPC proof
courier marshals an asset.

* taprpc: add marshal functions for universe RPC types

* proof: clarify doc for Proof.PrevOut

* asset: add asset method for retrieving PrevID which handles split commit

This commit adds a method to the Asset structure which returns the
asset's primary PrevID and takes account of the fact that the asset may
correspond to a split output.

* multi: add universe RPC proof courier

* tapgarden: add proof retrieval delay to custodian

* proof: remove roasbeef's TODO now that we have two different couriers

* rpc: add debug messages for InsertProof and QueryProof endpoints

* universe: allow registering non-issuance proofs in universe/multiverse

* universe: use previous asset snapshot when verifying transition proof

* itest: fix nits

* itest: add universe RPC harness and utilise for basic send

asset/asset.go

@@ -822,6 +822,37 @@ func (a *Asset) IsBurn() bool {
 	return IsBurnKey(a.ScriptKey.PubKey, a.PrevWitnesses[0])
 }
 
+// PrimaryPrevID returns the primary prev ID of an asset. This is the prev ID of
+// the first witness, unless the first witness is a split-commitment witness,
+// in which case it is the prev ID of the first witness of the root asset.
+// The first witness effectively corresponds to the asset's direct lineage.
+func (a *Asset) PrimaryPrevID() (*PrevID, error) {
+	if len(a.PrevWitnesses) == 0 {
+		return nil, fmt.Errorf("asset missing previous witnesses")
+	}
+
+	// The primary prev ID is stored on the root asset if this asset is a
+	// split output. We determine whether this asset is a split output by
+	// inspecting the first previous witness.
+	primaryWitness := a.PrevWitnesses[0]
+	isSplitOutput := IsSplitCommitWitness(primaryWitness)
+
+	// If this is a split output, then we need to look up the first PrevID
+	// in the split root asset.
+	if isSplitOutput {
+		rootAsset := primaryWitness.SplitCommitment.RootAsset
+		if len(rootAsset.PrevWitnesses) == 0 {
+			return nil, fmt.Errorf("asset missing previous " +
+				"witnesses")
+		}
+		return rootAsset.PrevWitnesses[0].PrevID, nil
+	}
+
+	// This asset is not a split output, so we can just return the PrevID
+	// found in the first witness.
+	return primaryWitness.PrevID, nil
+}
+
 // Copy returns a deep copy of an Asset.
 func (a *Asset) Copy() *Asset {
 	assetCopy := *a

cmd/tapcli/universe.go

@@ -7,6 +7,7 @@ import (
 
 	tap "github.com/lightninglabs/taproot-assets"
 	"github.com/lightninglabs/taproot-assets/proof"
+	"github.com/lightninglabs/taproot-assets/taprpc"
 	"github.com/lightninglabs/taproot-assets/taprpc/universerpc"
 	unirpc "github.com/lightninglabs/taproot-assets/taprpc/universerpc"
 	"github.com/lightningnetwork/lnd/lncfg"
@@ -417,7 +418,7 @@ func universeProofInsert(ctx *cli.Context) error {
 	if err != nil {
 		return err
 	}
-	rpcAsset, err := tap.MarshalAsset(
+	rpcAsset, err := taprpc.MarshalAsset(
 		ctxc, &assetProof.Asset, false, true, nil,
 	)
 	if err != nil {

itest/send_test.go

@@ -20,8 +20,8 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-// testBasicSend tests that we can properly send assets back and forth between
-// nodes.
+// testBasicSendUnidirectional tests that we can properly send assets back and
+// forth between nodes.
 func testBasicSendUnidirectional(t *harnessTest) {
 	var (
 		ctxb = context.Background()

itest/tapd_harness.go

@@ -177,6 +177,13 @@ func newTapdHarness(t *testing.T, ht *harnessTest, cfg tapdConfig,
 			ReceiverAckTimeout: receiverAckTimeout,
 			BackoffCfg:         backoffCfg,
 		}
+
+	case *UniverseRPCHarness:
+		finalCfg.DefaultProofCourierAddr = fmt.Sprintf(
+			"%s://%s", proof.UniverseRpcCourierType,
+			typedProofCourier.ListenAddr,
+		)
+
 	default:
 		finalCfg.DefaultProofCourierAddr = ""
 		finalCfg.HashMailCourier = nil

itest/test_harness.go

@@ -175,7 +175,7 @@ func (h *harnessTest) LogfTimestamped(format string, args ...interface{}) {
 }
 
 // shutdown stops both the mock universe and tapd server.
-func (h *harnessTest) shutdown(t *testing.T) error {
+func (h *harnessTest) shutdown(_ *testing.T) error {
 	h.universeServer.stop()
 
 	if h.proofCourier != nil {
@@ -284,6 +284,9 @@ func setupHarnesses(t *testing.T, ht *harnessTest,
 		port := nextAvailablePort()
 		apHarness := NewApertureHarness(ht.t, port)
 		proofCourier = &apHarness
+
+	case proof.UniverseRpcCourierType:
+		proofCourier = NewUniverseRPCHarness(t, ht, lndHarness.Bob)
 	}
 
 	// Start the proof courier harness if specified.

itest/test_list_on_test.go

@@ -43,6 +43,11 @@ var testCases = []*testCase{
 		test:             testBasicSendUnidirectional,
 		proofCourierType: proof.HashmailCourierType,
 	},
+	{
+		name:             "basic send universerpc proof courier",
+		test:             testBasicSendUnidirectional,
+		proofCourierType: proof.UniverseRpcCourierType,
+	},
 	{
 		name:             "resume pending package send",
 		test:             testResumePendingPackageSend,

itest/universerpc_harness.go

@@ -0,0 +1,51 @@
+package itest
+
+import (
+	"testing"
+
+	"github.com/lightninglabs/taproot-assets/proof"
+	"github.com/lightningnetwork/lnd/lntest/node"
+	"github.com/stretchr/testify/require"
+)
+
+// UniverseRPCHarness is an integration testing harness for the universe tap
+// service.
+type UniverseRPCHarness struct {
+	// service is the instance of the universe tap service.
+	service *tapdHarness
+
+	// ListenAddr is the address that the service is listening on.
+	ListenAddr string
+}
+
+// NewUniverseRPCHarness creates a new test harness for a universe tap service.
+func NewUniverseRPCHarness(t *testing.T, ht *harnessTest,
+	lndHarness *node.HarnessNode) *UniverseRPCHarness {
+
+	service, err := newTapdHarness(
+		t, ht, tapdConfig{
+			NetParams: harnessNetParams,
+			LndNode:   lndHarness,
+		}, nil, nil, nil,
+	)
+	require.NoError(t, err)
+
+	return &UniverseRPCHarness{
+		service:    service,
+		ListenAddr: service.rpcHost(),
+	}
+}
+
+// Start starts the service.
+func (h *UniverseRPCHarness) Start(_ chan error) error {
+	return h.service.start(false)
+}
+
+// Stop stops the service.
+func (h *UniverseRPCHarness) Stop() error {
+	return h.service.stop(true)
+}
+
+// Ensure that NewUniverseRPCHarness implements the proof.CourierHarness
+// interface.
+var _ proof.CourierHarness = (*UniverseRPCHarness)(nil)

proof/archive.go

@@ -57,6 +57,10 @@ type Locator struct {
 	// ScriptKey specifies the script key of the asset to fetch/store. This
 	// field MUST be specified.
 	ScriptKey btcec.PublicKey
+
+	// OutPoint is the outpoint of the associated asset. This field is
+	// optional.
+	OutPoint *wire.OutPoint
 }
 
 // Hash returns a SHA256 hash of the bytes serialized locator.