/
hexutil.go
220 lines (198 loc) · 4.89 KB
/
hexutil.go
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package common
import (
"encoding/hex"
"errors"
"fmt"
"math/big"
"strconv"
)
const uintBits = 32 << (uint64(^uint(0)) >> 63)
// Errors
var (
ErrEmptyString = &decError{"empty hex string"}
ErrSyntax = &decError{"invalid hex string"}
ErrMissingPrefix = &decError{"hex string without 0x prefix"}
ErrOddLength = &decError{"hex string of odd length"}
ErrEmptyNumber = &decError{"hex string \"0x\""}
ErrLeadingZero = &decError{"hex number with leading zero digits"}
ErrUint64Range = &decError{"hex number > 64 bits"}
ErrUintRange = &decError{fmt.Sprintf("hex number > %d bits", uintBits)}
ErrBig256Range = &decError{"hex number > 256 bits"}
)
type decError struct{ msg string }
func (err decError) Error() string { return err.msg }
// Decode decodes a hex string with 0x prefix.
func Decode(input string) ([]byte, error) {
if len(input) == 0 {
return nil, ErrEmptyString
}
if !has0xPrefix(input) {
return nil, ErrMissingPrefix
}
b, err := hex.DecodeString(input[2:])
if err != nil {
err = mapError(err)
}
return b, err
}
// MustDecode decodes a hex string with 0x prefix. It panics for invalid input.
func MustDecode(input string) []byte {
dec, err := Decode(input)
if err != nil {
panic(err)
}
return dec
}
// Encode encodes b as a hex string with 0x prefix.
func Encode(b []byte) string {
enc := make([]byte, len(b)*2+2)
copy(enc, "0x")
hex.Encode(enc[2:], b)
return string(enc)
}
// DecodeUint64 decodes a hex string with 0x prefix as a quantity.
func DecodeUint64(input string) (uint64, error) {
raw, err := checkNumber(input)
if err != nil {
return 0, err
}
dec, err := strconv.ParseUint(raw, 16, 64)
if err != nil {
err = mapError(err)
}
return dec, err
}
// MustDecodeUint64 decodes a hex string with 0x prefix as a quantity.
// It panics for invalid input.
func MustDecodeUint64(input string) uint64 {
dec, err := DecodeUint64(input)
if err != nil {
panic(err)
}
return dec
}
// EncodeUint64 encodes i as a hex string with 0x prefix.
func EncodeUint64(i uint64) string {
enc := make([]byte, 2, 10)
copy(enc, "0x")
return string(strconv.AppendUint(enc, i, 16))
}
var bigWordNibbles int
func init() {
// This is a weird way to compute the number of nibbles required for big.Word.
// The usual way would be to use constant arithmetic but go vet can't handle that.
b, _ := new(big.Int).SetString("FFFFFFFFFF", 16)
switch len(b.Bits()) {
case 1:
bigWordNibbles = 16
case 2:
bigWordNibbles = 8
default:
panic("weird big.Word size")
}
}
// DecodeBig decodes a hex string with 0x prefix as a quantity.
// Numbers larger than 256 bits are not accepted.
func DecodeBig(input string) (*big.Int, error) {
raw, err := checkNumber(input)
if err != nil {
return nil, err
}
if len(raw) > 64 {
return nil, ErrBig256Range
}
words := make([]big.Word, len(raw)/bigWordNibbles+1)
end := len(raw)
for i := range words {
start := end - bigWordNibbles
if start < 0 {
start = 0
}
for ri := start; ri < end; ri++ {
nib := decodeNibble(raw[ri])
if nib == badNibble {
return nil, ErrSyntax
}
words[i] *= 16
words[i] += big.Word(nib)
}
end = start
}
dec := new(big.Int).SetBits(words)
return dec, nil
}
// MustDecodeBig decodes a hex string with 0x prefix as a quantity.
// It panics for invalid input.
func MustDecodeBig(input string) *big.Int {
dec, err := DecodeBig(input)
if err != nil {
panic(err)
}
return dec
}
// EncodeBig encodes bigint as a hex string with 0x prefix.
// The sign of the integer is ignored.
func EncodeBig(bigint *big.Int) string {
nbits := bigint.BitLen()
if nbits == 0 {
return "0x0"
}
return fmt.Sprintf("%#x", bigint)
}
func has0xPrefix(input string) bool {
return len(input) >= 2 && input[0] == '0' && (input[1] == 'x' || input[1] == 'X')
}
func checkNumber(input string) (raw string, err error) {
if len(input) == 0 {
return "", ErrEmptyString
}
if !has0xPrefix(input) {
return "", ErrMissingPrefix
}
input = input[2:]
if len(input) == 0 {
return "", ErrEmptyNumber
}
if len(input) > 1 && input[0] == '0' {
return "", ErrLeadingZero
}
return input, nil
}
const badNibble = ^uint64(0)
func decodeNibble(in byte) uint64 {
switch {
case in >= '0' && in <= '9':
return uint64(in - '0')
case in >= 'A' && in <= 'F':
return uint64(in - 'A' + 10)
case in >= 'a' && in <= 'f':
return uint64(in - 'a' + 10)
default:
return badNibble
}
}
func mapError(err error) error {
if err, ok := err.(*strconv.NumError); ok {
switch err.Err {
case strconv.ErrRange:
return ErrUint64Range
case strconv.ErrSyntax:
return ErrSyntax
}
}
if _, ok := err.(hex.InvalidByteError); ok {
return ErrSyntax
}
if err == hex.ErrLength {
return ErrOddLength
}
return err
}
func BigIntMustFromString(number string) *big.Int {
bigInt := new(big.Int)
bigInt, isSuccess := bigInt.SetString(number, 10)
if !isSuccess {
panic(errors.New("cannt decode input string to big int"))
}
return bigInt
}