btcd: add new RPC method testmempoolaccept

rpcserver.go

@@ -178,6 +178,7 @@ var rpcHandlersBeforeInit = map[string]commandHandler{
 	"verifychain":            handleVerifyChain,
 	"verifymessage":          handleVerifyMessage,
 	"version":                handleVersion,
+	"testmempoolaccept":      handleTestMempoolAccept,
 }
 
 // list of commands that we recognize, but for which btcd has no support because
@@ -3783,6 +3784,83 @@ func handleVersion(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (in
 	return result, nil
 }
 
+// handleTestMempoolAccept implements the testmempoolaccept command.
+func handleTestMempoolAccept(s *rpcServer, cmd interface{},
+	closeChan <-chan struct{}) (interface{}, error) {
+
+	c := cmd.(*btcjson.TestMempoolAcceptCmd)
+
+	// Create txns to hold the decoded tx.
+	txns := make([]*btcutil.Tx, 0, len(c.RawTxns))
+
+	// Iterate the raw hex slice and decode them.
+	for _, rawTx := range c.RawTxns {
+		rawBytes, err := hex.DecodeString(rawTx)
+		if err != nil {
+			return nil, rpcDecodeHexError(rawTx)
+		}
+
+		tx, err := btcutil.NewTxFromBytes(rawBytes)
+		if err != nil {
+			return nil, &btcjson.RPCError{
+				Code:    btcjson.ErrRPCDeserialization,
+				Message: "TX decode failed: " + err.Error(),
+			}
+		}
+
+		txns = append(txns, tx)
+	}
+
+	results := make([]*btcjson.TestMempoolAcceptResult, 0, len(txns))
+	for _, tx := range txns {
+		// Create a test result item.
+		item := &btcjson.TestMempoolAcceptResult{
+			Txid:  tx.Hash().String(),
+			Wtxid: tx.WitnessHash().String(),
+		}
+
+		// Check the mempool acceptance.
+		result, err := s.cfg.TxMemPool.CheckMempoolAcceptance(tx)
+
+		// If an error is returned, this tx is not allow, hence we
+		// record the reason.
+		if err != nil {
+			item.Allowed = false
+
+			// TODO(yy): differentiate the errors and put package
+			// error in `PackageError` field.
+			item.RejectReason = err.Error()
+
+			// Move to the next transaction.
+			continue
+		}
+
+		// If this transaction is an orphan, it's not allowed.
+		if result.MissingParents != nil {
+			item.Allowed = false
+
+			// NOTE: "missing-inputs" is what bitcoind returns
+			// here, so we mimic the same error message.
+			item.RejectReason = "missing-inputs"
+
+			// Move to the next transaction.
+			continue
+		}
+
+		// Otherwise this tx is allowed, we now patch the fields in
+		// `TestMempoolAcceptItem` as much as possible.
+		item.Allowed = true
+		item.Vsize = int32(result.TxSize)
+		item.Fees = &btcjson.TestMempoolAcceptFees{
+			Base: result.TxFee.ToBTC(),
+		}
+
+		results = append(results, item)
+	}
+
+	return results, nil
+}
+
 // rpcServer provides a concurrent safe RPC server to a chain server.
 type rpcServer struct {
 	started                int32

rpcserverhelp.go

@@ -708,6 +708,23 @@ var helpDescsEnUS = map[string]string{
 	"versionresult-patch":         "The patch component of the JSON-RPC API version",
 	"versionresult-prerelease":    "Prerelease info about the current build",
 	"versionresult-buildmetadata": "Metadata about the current build",
+
+	// TestMempoolAcceptCmd help.
+	"testmempoolaccept--synopsis":  "Returns result of mempool acceptance tests indicating if raw transaction(s) would be accepted by mempool.",
+	"testmempoolaccept-rawtxns":    "Serialized transactions to test.",
+	"testmempoolaccept-maxfeerate": "Maximum acceptable fee rate in BTC/kB",
+
+	// TestMempoolAcceptCmd result help.
+	"testmempoolacceptresult-txid":             "The transaction hash in hex.",
+	"testmempoolacceptresult-wtxid":            "The transaction witness hash in hex.",
+	"testmempoolacceptresult-package-error":    "Package validation error, if any (only possible if rawtxs had more than 1 transaction).",
+	"testmempoolacceptresult-allowed":          "Whether the transaction would be accepted to the mempool.",
+	"testmempoolacceptresult-vsize":            "Virtual transaction size as defined in BIP 141.(only present when 'allowed' is true)",
+	"testmempoolacceptresult-reject-reason":    "Rejection string (only present when 'allowed' is false).",
+	"testmempoolacceptresult-fees":             "Transaction fees (only present if 'allowed' is true).",
+	"testmempoolacceptfees-base":               "Transaction fees (only present if 'allowed' is true).",
+	"testmempoolacceptfees-effective-feerate":  "The effective feerate in BTC per KvB.",
+	"testmempoolacceptfees-effective-includes": "Transactions whose fees and vsizes are included in effective-feerate. Each item is a transaction wtxid in hex.",
 }
 
 // rpcResultTypes specifies the result types that each RPC command can return.
@@ -762,6 +779,7 @@ var rpcResultTypes = map[string][]interface{}{
 	"verifychain":            {(*bool)(nil)},
 	"verifymessage":          {(*bool)(nil)},
 	"version":                {(*map[string]btcjson.VersionResult)(nil)},
+	"testmempoolaccept":      {(*[]btcjson.TestMempoolAcceptResult)(nil)},
 
 	// Websocket commands.
 	"loadtxfilter":              nil,