cmd/rlpdump: add support for text to rlp (#23745)

This PR adds support for the rlpdump tool to go from text format to RLP.

Author: holiman

cmd/rlpdump/main.go

@@ -18,26 +18,30 @@
 package main
 
 import (
+	"bufio"
 	"bytes"
+	"container/list"
 	"encoding/hex"
 	"flag"
 	"fmt"
 	"io"
 	"os"
 	"strings"
 
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
 var (
-	hexMode = flag.String("hex", "", "dump given hex data")
-	noASCII = flag.Bool("noascii", false, "don't print ASCII strings readably")
-	single  = flag.Bool("single", false, "print only the first element, discard the rest")
+	hexMode     = flag.String("hex", "", "dump given hex data")
+	reverseMode = flag.Bool("reverse", false, "convert ASCII to rlp")
+	noASCII     = flag.Bool("noascii", false, "don't print ASCII strings readably")
+	single      = flag.Bool("single", false, "print only the first element, discard the rest")
 )
 
 func init() {
 	flag.Usage = func() {
-		fmt.Fprintln(os.Stderr, "Usage:", os.Args[0], "[-noascii] [-hex <data>] [filename]")
+		fmt.Fprintln(os.Stderr, "Usage:", os.Args[0], "[-noascii] [-hex <data>][-reverse] [filename]")
 		flag.PrintDefaults()
 		fmt.Fprintln(os.Stderr, `
 Dumps RLP data from the given file in readable form.
@@ -73,23 +77,40 @@ func main() {
 		flag.Usage()
 		os.Exit(2)
 	}
+	out := os.Stdout
+	if *reverseMode {
+		data, err := textToRlp(r)
+		if err != nil {
+			die(err)
+		}
+		fmt.Printf("0x%x\n", data)
+		return
+	} else {
+		err := rlpToText(r, out)
+		if err != nil {
+			die(err)
+		}
+	}
+}
 
+func rlpToText(r io.Reader, out io.Writer) error {
 	s := rlp.NewStream(r, 0)
 	for {
-		if err := dump(s, 0); err != nil {
+		if err := dump(s, 0, out); err != nil {
 			if err != io.EOF {
-				die(err)
+				return err
 			}
 			break
 		}
-		fmt.Println()
+		fmt.Fprintln(out)
 		if *single {
 			break
 		}
 	}
+	return nil
 }
 
-func dump(s *rlp.Stream, depth int) error {
+func dump(s *rlp.Stream, depth int, out io.Writer) error {
 	kind, size, err := s.Kind()
 	if err != nil {
 		return err
@@ -101,28 +122,28 @@ func dump(s *rlp.Stream, depth int) error {
 			return err
 		}
 		if len(str) == 0 || !*noASCII && isASCII(str) {
-			fmt.Printf("%s%q", ws(depth), str)
+			fmt.Fprintf(out, "%s%q", ws(depth), str)
 		} else {
-			fmt.Printf("%s%x", ws(depth), str)
+			fmt.Fprintf(out, "%s%x", ws(depth), str)
 		}
 	case rlp.List:
 		s.List()
 		defer s.ListEnd()
 		if size == 0 {
-			fmt.Print(ws(depth) + "[]")
+			fmt.Fprintf(out, ws(depth)+"[]")
 		} else {
-			fmt.Println(ws(depth) + "[")
+			fmt.Fprintln(out, ws(depth)+"[")
 			for i := 0; ; i++ {
 				if i > 0 {
-					fmt.Print(",\n")
+					fmt.Fprint(out, ",\n")
 				}
-				if err := dump(s, depth+1); err == rlp.EOL {
+				if err := dump(s, depth+1, out); err == rlp.EOL {
 					break
 				} else if err != nil {
 					return err
 				}
 			}
-			fmt.Print(ws(depth) + "]")
+			fmt.Fprint(out, ws(depth)+"]")
 		}
 	}
 	return nil
@@ -145,3 +166,45 @@ func die(args ...interface{}) {
 	fmt.Fprintln(os.Stderr, args...)
 	os.Exit(1)
 }
+
+// textToRlp converts text into RLP (best effort).
+func textToRlp(r io.Reader) ([]byte, error) {
+	// We're expecting the input to be well-formed, meaning that
+	// - each element is on a separate line
+	// - each line is either an (element OR a list start/end) + comma
+	// - an element is either hex-encoded bytes OR a quoted string
+	var (
+		scanner = bufio.NewScanner(r)
+		obj     []interface{}
+		stack   = list.New()
+	)
+	for scanner.Scan() {
+		t := strings.TrimSpace(scanner.Text())
+		if len(t) == 0 {
+			continue
+		}
+		switch t {
+		case "[": // list start
+			stack.PushFront(obj)
+			obj = make([]interface{}, 0)
+		case "]", "],": // list end
+			parent := stack.Remove(stack.Front()).([]interface{})
+			obj = append(parent, obj)
+		case "[],": // empty list
+			obj = append(obj, make([]interface{}, 0))
+		default: // element
+			data := []byte(t)[:len(t)-1] // cut off comma
+			if data[0] == '"' {          // ascii string
+				data = []byte(t)[1 : len(data)-1]
+			} else { // hex data
+				data = common.FromHex(string(data))
+			}
+			obj = append(obj, data)
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+	data, err := rlp.EncodeToBytes(obj[0])
+	return data, err
+}

cmd/rlpdump/rlpdump_test.go

@@ -0,0 +1,65 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+)
+
+func TestRoundtrip(t *testing.T) {
+	for i, want := range []string{
+		"0xf880806482520894d0d0d0d0d0d0d0d0d0d0d0d0d0d0d0d0d0d0d0d0a1010000000000000000000000000000000000000000000000000000000000000001801ba0c16787a8e25e941d67691954642876c08f00996163ae7dfadbbfd6cd436f549da06180e5626cae31590f40641fe8f63734316c4bfeb4cdfab6714198c1044d2e28",
+		"0xd5c0d3cb84746573742a2a808213378667617a6f6e6b",
+		"0xc780c0c1c0825208",
+	} {
+		var out strings.Builder
+		err := rlpToText(bytes.NewReader(common.FromHex(want)), &out)
+		if err != nil {
+			t.Fatal(err)
+		}
+		text := out.String()
+		rlpBytes, err := textToRlp(strings.NewReader(text))
+		if err != nil {
+			t.Errorf("test %d: error %v", i, err)
+			continue
+		}
+		have := fmt.Sprintf("0x%x", rlpBytes)
+		if have != want {
+			t.Errorf("test %d: have\n%v\nwant:\n%v\n", i, have, want)
+		}
+	}
+}
+
+func TestTextToRlp(t *testing.T) {
+	type tc struct {
+		text string
+		want string
+	}
+	cases := []tc{
+		{
+			text: `[
+  "",
+  [],
+[     
+ [],
+    ],
+  5208,
+]`,
+			want: "0xc780c0c1c0825208",
+		},
+	}
+	for i, tc := range cases {
+		have, err := textToRlp(strings.NewReader(tc.text))
+		if err != nil {
+			t.Errorf("test %d: error %v", i, err)
+			continue
+		}
+		if hexutil.Encode(have) != tc.want {
+			t.Errorf("test %d:\nhave %v\nwant %v", i, hexutil.Encode(have), tc.want)
+		}
+	}
+}