tappsbt+itest: make V2 address transfers interactive

Because we don't need to be able to fully predict the asset leaf as it
is put on chain (which was the case for V0 and V1 addresses), we can
optimize chain usage by avoiding the creation of a tombstone output on
full value sends (meaning we use an interactive transfer scheme for V2
addresses, since the receiver will learn about the proofs from the auth
mailbox and doesn't need to predict the leave(s) themselves).
That means we no longer have to create a zero-value change output that
locks 1k sats until we implement garbage collection if the user wants to
send all assets. So fewer outputs created on-chain and fewer sats locked
for the user.

Author: guggero

itest/addrs_v2_test.go

@@ -271,8 +271,7 @@ func testAddressV2WithGroupKey(t *harnessTest) {
 	AssertAssetOutboundTransferWithOutputs(
 		t.t, t.lndHarness.Miner().Client, t.tapd,
 		sendResp.Transfer, [][]byte{firstAssetID, secondAssetID},
-		[]uint64{0, firstAsset.Amount, 0, secondAsset.Amount}, 0,
-		1, 4, true,
+		[]uint64{firstAsset.Amount, secondAsset.Amount}, 0, 1, 2, true,
 	)
 	AssertReceiveEventsCustom(t.t, addrEvents, []taprpc.AddrEventStatus{
 		statusConfirmed,
@@ -284,13 +283,6 @@ func testAddressV2WithGroupKey(t *harnessTest) {
 		WithNumUtxos(2),
 	)
 
-	// The sending node should only have two tombstone outputs, but the
-	// total value should be zero.
-	AssertBalanceByGroup(
-		t.t, t.tapd, hex.EncodeToString(groupKey), 0, WithNumUtxos(2),
-		WithAllScriptKeyTypes(),
-	)
-
 	// We now make sure we can spend those assets again by sending
 	// them back to ourselves, using an address with an amount.
 	groupAddrBob2, _ := NewAddrWithEventStream(
@@ -354,8 +346,8 @@ func testAddressV2WithGroupKey(t *harnessTest) {
 	AssertAssetOutboundTransferWithOutputs(
 		t.t, t.lndHarness.Miner().Client, bobTapd,
 		sendResp3.Transfer, [][]byte{firstAssetID, secondAssetID},
-		[]uint64{0, totalAmount/2 - 50, 50, 0, totalAmount / 2}, 1,
-		2, 5, true,
+		[]uint64{totalAmount/2 - 50, 50, totalAmount / 2}, 1, 2, 3,
+		true,
 	)
 	AssertBalanceByGroup(
 		t.t, t.tapd, hex.EncodeToString(groupKey), totalAmount,
@@ -493,8 +485,8 @@ func testAddressV2WithGroupKeyMultipleRoundTrips(t *harnessTest) {
 	AssertAssetOutboundTransferWithOutputs(
 		t.t, t.lndHarness.Miner().Client, t.tapd,
 		sendResp.Transfer, [][]byte{firstAssetID},
-		[]uint64{0, firstAsset.Amount}, currentTransferIdx,
-		numTransfers, 2, true,
+		[]uint64{firstAsset.Amount}, currentTransferIdx,
+		numTransfers, 1, true,
 	)
 
 	AssertAddrEventByStatus(t.t, bobTapd, statusCompleted, numTransfers)
@@ -516,8 +508,8 @@ func testAddressV2WithGroupKeyMultipleRoundTrips(t *harnessTest) {
 	AssertAssetOutboundTransferWithOutputs(
 		t.t, t.lndHarness.Miner().Client, t.tapd,
 		sendResp.Transfer, [][]byte{secondAssetID},
-		[]uint64{0, secondAsset.Amount}, currentTransferIdx,
-		numTransfers, 2, true,
+		[]uint64{secondAsset.Amount}, currentTransferIdx,
+		numTransfers, 1, true,
 	)
 
 	AssertAddrEventByStatus(t.t, bobTapd, statusCompleted, numTransfers)
@@ -539,8 +531,8 @@ func testAddressV2WithGroupKeyMultipleRoundTrips(t *harnessTest) {
 	AssertAssetOutboundTransferWithOutputs(
 		t.t, t.lndHarness.Miner().Client, t.tapd,
 		sendResp.Transfer, [][]byte{thirdAssetID},
-		[]uint64{0, thirdAsset.Amount}, currentTransferIdx,
-		numTransfers, 2, true,
+		[]uint64{thirdAsset.Amount}, currentTransferIdx,
+		numTransfers, 1, true,
 	)
 
 	AssertAddrEventByStatus(t.t, bobTapd, statusCompleted, numTransfers)
@@ -644,8 +636,8 @@ func testAddressV2WithGroupKeyMultipleRoundTrips(t *harnessTest) {
 		AssertAssetOutboundTransferWithOutputs(
 			t.t, t.lndHarness.Miner().Client, t.tapd,
 			sendResp.Transfer, [][]byte{assetIDs[idx]},
-			[]uint64{0, amount}, currentTransferIdx, numTransfers,
-			2, true,
+			[]uint64{amount}, currentTransferIdx, numTransfers, 1,
+			true,
 		)
 
 		AssertAddrEventByStatus(

tappsbt/create.go

@@ -39,8 +39,47 @@ func FromAddresses(receiverAddrs []*address.Tap,
 	switch firstAddr.Version {
 	case address.V0:
 		pkt.Version = V0
-	case address.V1, address.V2:
+	case address.V1:
 		pkt.Version = V1
+	case address.V2:
+		pkt.Version = V1
+
+		// All sends to V0 and V1 addresses _NEED_ to be non-
+		// interactive, because the receiver needs to be able to predict
+		// the final on-chain Taproot output key all the way up,
+		// starting at the asset leaf, assuming a split output.
+		// For V2 addresses that is no longer the case, since we are
+		// relying on the output list to be sent in a separate message
+		// and the proofs being fetched from a universe server. So we
+		// can use interactive (e.g. full value sends without tombstone)
+		// sends to V2 addresses.
+		for idx := range receiverAddrs {
+			addr := receiverAddrs[idx]
+			if addr.Version != firstAddr.Version {
+				return nil, fmt.Errorf("mixed address versions")
+			}
+
+			//nolint:lll
+			pkt.Outputs = append(pkt.Outputs, &VOutput{
+				AssetVersion: addr.AssetVersion,
+				Amount:       addr.Amount,
+				Interactive:  true,
+				// We can directly use the index as the anchor
+				// output here, a change output will be added
+				// by the funding logic at the end if necessary.
+				AnchorOutputIndex: uint32(idx),
+				ScriptKey: asset.NewScriptKey(
+					&addr.ScriptKey,
+				),
+				AnchorOutputInternalKey:      &addr.InternalKey,
+				AnchorOutputTapscriptSibling: addr.TapscriptSibling,
+				ProofDeliveryAddress:         &addr.ProofCourierAddr,
+				Address:                      addr,
+			})
+		}
+
+		return pkt, nil
+
 	default:
 		return nil, address.ErrUnknownVersion
 	}

tappsbt/testdata/psbt_encoding_generated.json

@@ -28,36 +28,12 @@
           }
         ],
         "outputs": [
-          {
-            "amount": 0,
-            "type": 1,
-            "asset_version": 0,
-            "interactive": false,
-            "anchor_output_index": 0,
-            "anchor_output_internal_key": "",
-            "anchor_output_bip32_derivation": null,
-            "anchor_output_tr_bip32_derivation": null,
-            "anchor_output_tapscript_sibling": "",
-            "asset": null,
-            "split_asset": null,
-            "pk_script": "51207c79b9b26e463895eef5679d8558942c86c4ad2233adef01bc3e6d540b3653fe",
-            "bip32_derivation": null,
-            "tr_bip32_derivation": null,
-            "tr_internal_key": "",
-            "tr_merkle_root": "",
-            "proof_delivery_address": "",
-            "proof_suffix": null,
-            "relative_lock_time": 0,
-            "lock_time": 0,
-            "alt_leaves": null,
-            "address": null
-          },
           {
             "amount": 1,
             "type": 0,
             "asset_version": 1,
-            "interactive": false,
-            "anchor_output_index": 1,
+            "interactive": true,
+            "anchor_output_index": 0,
             "anchor_output_internal_key": "02daf785f20dcb5bb06bef717296c3894ed2564d5e3f8325d2f6bad1315aaad16c",
             "anchor_output_bip32_derivation": null,
             "anchor_output_tr_bip32_derivation": null,
@@ -116,7 +92,7 @@
         "version": 1,
         "chain_params_hrp": "tapbc"
       },
-      "expected": "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",
+      "expected": "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",
       "comment": "minimal packet"
     },
     {