cmd/evm: implement input txs via rlp in t8n tool (#23138)

In many cases, it's desireable to use already-signed transactions as input to the state transition, instead of having the evm sign them internally (for example to use malformed or not-yet-valid transactions). This PR adds support + docs for that feature.

cmd/evm/internal/t8ntool/transition.go

@@ -25,6 +25,7 @@ import (
 	"math/big"
 	"os"
 	"path"
+	"strings"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
@@ -72,6 +73,7 @@ type input struct {
 	Alloc core.GenesisAlloc `json:"alloc,omitempty"`
 	Env   *stEnv            `json:"env,omitempty"`
 	Txs   []*txWithKey      `json:"txs,omitempty"`
+	TxRlp string            `json:"txsRlp,omitempty"`
 }
 
 func Main(ctx *cli.Context) error {
@@ -199,11 +201,44 @@ func Main(ctx *cli.Context) error {
 		}
 		defer inFile.Close()
 		decoder := json.NewDecoder(inFile)
-		if err := decoder.Decode(&txsWithKeys); err != nil {
-			return NewError(ErrorJson, fmt.Errorf("failed unmarshaling txs-file: %v", err))
+		if strings.HasSuffix(txStr, ".rlp") {
+			var body hexutil.Bytes
+			if err := decoder.Decode(&body); err != nil {
+				return err
+			}
+			var txs types.Transactions
+			if err := rlp.DecodeBytes(body, &txs); err != nil {
+				return err
+			}
+			for _, tx := range txs {
+				txsWithKeys = append(txsWithKeys, &txWithKey{
+					key: nil,
+					tx:  tx,
+				})
+			}
+		} else {
+			if err := decoder.Decode(&txsWithKeys); err != nil {
+				return NewError(ErrorJson, fmt.Errorf("failed unmarshaling txs-file: %v", err))
+			}
 		}
 	} else {
-		txsWithKeys = inputData.Txs
+		if len(inputData.TxRlp) > 0 {
+			// Decode the body of already signed transactions
+			body := common.FromHex(inputData.TxRlp)
+			var txs types.Transactions
+			if err := rlp.DecodeBytes(body, &txs); err != nil {
+				return err
+			}
+			for _, tx := range txs {
+				txsWithKeys = append(txsWithKeys, &txWithKey{
+					key: nil,
+					tx:  tx,
+				})
+			}
+		} else {
+			// JSON encoded transactions
+			txsWithKeys = inputData.Txs
+		}
 	}
 	// We may have to sign the transactions.
 	signer := types.MakeSigner(chainConfig, big.NewInt(int64(prestate.Env.Number)))
@@ -365,6 +400,7 @@ func dispatchOutput(ctx *cli.Context, baseDir string, result *ExecutionResult, a
 			return NewError(ErrorJson, fmt.Errorf("failed marshalling output: %v", err))
 		}
 		os.Stdout.Write(b)
+		os.Stdout.Write([]byte("\n"))
 	}
 	if len(stdErrObject) > 0 {
 		b, err := json.MarshalIndent(stdErrObject, "", " ")
@@ -372,6 +408,7 @@ func dispatchOutput(ctx *cli.Context, baseDir string, result *ExecutionResult, a
 			return NewError(ErrorJson, fmt.Errorf("failed marshalling output: %v", err))
 		}
 		os.Stderr.Write(b)
+		os.Stderr.Write([]byte("\n"))
 	}
 	return nil
 }