btcjson: add new command GetTxSpendingPrevOutCmd

btcjson/chainsvrcmds.go

@@ -1064,6 +1064,38 @@ func NewTestMempoolAcceptCmd(rawTxns []string,
 	}
 }
 
+// GetTxSpendingPrevOutCmd defines the gettxspendingprevout JSON-RPC command.
+type GetTxSpendingPrevOutCmd struct {
+	// Outputs is a list of transaction outputs to query.
+	Outputs []*GetTxSpendingPrevOutCmdOutput
+}
+
+// GetTxSpendingPrevOutCmdOutput defines the output to query for the
+// gettxspendingprevout JSON-RPC command.
+type GetTxSpendingPrevOutCmdOutput struct {
+	Txid string `json:"txid"`
+	Vout uint32 `json:"vout"`
+}
+
+// NewGetTxSpendingPrevOutCmd returns a new instance which can be used to issue
+// a gettxspendingprevout JSON-RPC command.
+func NewGetTxSpendingPrevOutCmd(
+	outpoints []wire.OutPoint) *GetTxSpendingPrevOutCmd {
+
+	outputs := make([]*GetTxSpendingPrevOutCmdOutput, 0, len(outpoints))
+
+	for _, op := range outpoints {
+		outputs = append(outputs, &GetTxSpendingPrevOutCmdOutput{
+			Txid: op.Hash.String(),
+			Vout: op.Index,
+		})
+	}
+
+	return &GetTxSpendingPrevOutCmd{
+		Outputs: outputs,
+	}
+}
+
 func init() {
 	// No special flags for commands in this file.
 	flags := UsageFlag(0)
@@ -1125,4 +1157,5 @@ func init() {
 	MustRegisterCmd("verifymessage", (*VerifyMessageCmd)(nil), flags)
 	MustRegisterCmd("verifytxoutproof", (*VerifyTxOutProofCmd)(nil), flags)
 	MustRegisterCmd("testmempoolaccept", (*TestMempoolAcceptCmd)(nil), flags)
+	MustRegisterCmd("gettxspendingprevout", (*GetTxSpendingPrevOutCmd)(nil), flags)
 }

btcjson/chainsvrcmds_test.go

@@ -13,6 +13,7 @@ import (
 	"testing"
 
 	"github.com/btcsuite/btcd/btcjson"
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 )
 
@@ -1500,6 +1501,29 @@ func TestChainSvrCmds(t *testing.T) {
 				MaxFeeRate: 0.01,
 			},
 		},
+		{
+			name: "gettxspendingprevout",
+			newCmd: func() (interface{}, error) {
+				return btcjson.NewCmd(
+					"gettxspendingprevout",
+					[]*btcjson.GetTxSpendingPrevOutCmdOutput{
+						{Txid: "0000000000000000000000000000000000000000000000000000000000000001", Vout: 0},
+					})
+			},
+			staticCmd: func() interface{} {
+				outputs := []wire.OutPoint{
+					{Hash: chainhash.Hash{1}, Index: 0},
+				}
+				return btcjson.NewGetTxSpendingPrevOutCmd(outputs)
+			},
+			marshalled: `{"jsonrpc":"1.0","method":"gettxspendingprevout","params":[[{"txid":"0000000000000000000000000000000000000000000000000000000000000001","vout":0}]],"id":1}`,
+			unmarshalled: &btcjson.GetTxSpendingPrevOutCmd{
+				Outputs: []*btcjson.GetTxSpendingPrevOutCmdOutput{{
+					Txid: "0000000000000000000000000000000000000000000000000000000000000001",
+					Vout: 0,
+				}},
+			},
+		},
 	}
 
 	t.Logf("Running %d tests", len(tests))

btcjson/chainsvrresults.go

@@ -911,3 +911,17 @@ type TestMempoolAcceptFees struct {
 	// NOTE: this field only exists in bitcoind v25.0 and above.
 	EffectiveIncludes []string `json:"effective-includes"`
 }
+
+// GetTxSpendingPrevOutResult defines a single item returned from the
+// gettxspendingprevout command.
+type GetTxSpendingPrevOutResult struct {
+	// Txid is the transaction id of the checked output.
+	Txid string `json:"txid"`
+
+	// Vout is the vout value of the checked output.
+	Vout uint32 `json:"vout"`
+
+	// SpendingTxid is the transaction id of the mempool transaction
+	// spending this output (omitted if unspent).
+	SpendingTxid string `json:"spendingtxid,omitempty"`
+}