// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package hexutil
import (
"encoding/hex"
"errors"
"fmt"
"math/big"
"strconv"
)
var (
jsonNull = []byte("null")
jsonZero = []byte(`"0x0"`)
errNonString = errors.New("cannot unmarshal non-string as hex data")
errNegativeBigInt = errors.New("hexutil.Big: can't marshal negative integer")
)
// Bytes marshals/unmarshals as a JSON string with 0x prefix.
// The empty slice marshals as "0x".
type Bytes []byte
// MarshalJSON implements json.Marshaler.
func (b Bytes) MarshalJSON() ([]byte, error) {
result := make([]byte, len(b)*2+4)
copy(result, `"0x`)
hex.Encode(result[3:], b)
result[len(result)-1] = '"'
return result, nil
}
// UnmarshalJSON implements json.Unmarshaler.
func (b *Bytes) UnmarshalJSON(input []byte) error {
raw, err := checkJSON(input)
if err != nil {
return err
}
dec := make([]byte, len(raw)/2)
if _, err = hex.Decode(dec, raw); err != nil {
err = mapError(err)
} else {
*b = dec
}
return err
}
// String returns the hex encoding of b.
func (b Bytes) String() string {
return Encode(b)
}
// UnmarshalJSON decodes input as a JSON string with 0x prefix. The length of out
// determines the required input length. This function is commonly used to implement the
// UnmarshalJSON method for fixed-size types:
//
// type Foo [8]byte
//
// func (f *Foo) UnmarshalJSON(input []byte) error {
// return hexutil.UnmarshalJSON("Foo", input, f[:])
// }
func UnmarshalJSON(typname string, input, out []byte) error {
raw, err := checkJSON(input)
if err != nil {
return err
}
if len(raw)/2 != len(out) {
return fmt.Errorf("hex string has length %d, want %d for %s", len(raw), len(out)*2, typname)
}
// Pre-verify syntax before modifying out.
for _, b := range raw {
if decodeNibble(b) == badNibble {
return ErrSyntax
}
}
hex.Decode(out, raw)
return nil
}
// Big marshals/unmarshals as a JSON string with 0x prefix. The zero value marshals as
// "0x0". Negative integers are not supported at this time. Attempting to marshal them
// will return an error.
type Big big.Int
// MarshalJSON implements json.Marshaler.
func (b *Big) MarshalJSON() ([]byte, error) {
if b == nil {
return jsonNull, nil
}
bigint := (*big.Int)(b)
if bigint.Sign() == -1 {
return nil, errNegativeBigInt
}
nbits := bigint.BitLen()
if nbits == 0 {
return jsonZero, nil
}
enc := fmt.Sprintf(`"0x%x"`, bigint)
return []byte(enc), nil
}
// UnmarshalJSON implements json.Unmarshaler.
func (b *Big) UnmarshalJSON(input []byte) error {
raw, err := checkNumberJSON(input)
if err != nil {
return err
}
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 ErrSyntax
}
words[i] *= 16
words[i] += big.Word(nib)
}
end = start
}
var dec big.Int
dec.SetBits(words)
*b = (Big)(dec)
return nil
}
// ToInt converts b to a big.Int.
func (b *Big) ToInt() *big.Int {
return (*big.Int)(b)
}
// String returns the hex encoding of b.
func (b *Big) String() string {
return EncodeBig(b.ToInt())
}
// Uint64 marshals/unmarshals as a JSON string with 0x prefix.
// The zero value marshals as "0x0".
type Uint64 uint64
// MarshalJSON implements json.Marshaler.
func (b Uint64) MarshalJSON() ([]byte, error) {
buf := make([]byte, 3, 12)
copy(buf, `"0x`)
buf = strconv.AppendUint(buf, uint64(b), 16)
buf = append(buf, '"')
return buf, nil
}
// UnmarshalJSON implements json.Unmarshaler.
func (b *Uint64) UnmarshalJSON(input []byte) error {
raw, err := checkNumberJSON(input)
if err != nil {
return err
}
if len(raw) > 16 {
return ErrUint64Range
}
var dec uint64
for _, byte := range raw {
nib := decodeNibble(byte)
if nib == badNibble {
return ErrSyntax
}
dec *= 16
dec += uint64(nib)
}
*b = Uint64(dec)
return nil
}
// String returns the hex encoding of b.
func (b Uint64) String() string {
return EncodeUint64(uint64(b))
}
// Uint marshals/unmarshals as a JSON string with 0x prefix.
// The zero value marshals as "0x0".
type Uint uint
// MarshalJSON implements json.Marshaler.
func (b Uint) MarshalJSON() ([]byte, error) {
return Uint64(b).MarshalJSON()
}
// UnmarshalJSON implements json.Unmarshaler.
func (b *Uint) UnmarshalJSON(input []byte) error {
var u64 Uint64
err := u64.UnmarshalJSON(input)
if err != nil {
return err
} else if u64 > Uint64(^uint(0)) {
return ErrUintRange
}
*b = Uint(u64)
return nil
}
// String returns the hex encoding of b.
func (b Uint) String() string {
return EncodeUint64(uint64(b))
}
func isString(input []byte) bool {
return len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"'
}
func bytesHave0xPrefix(input []byte) bool {
return len(input) >= 2 && input[0] == '0' && (input[1] == 'x' || input[1] == 'X')
}
func checkJSON(input []byte) (raw []byte, err error) {
if !isString(input) {
return nil, errNonString
}
if len(input) == 2 {
return nil, nil // empty strings are allowed
}
if !bytesHave0xPrefix(input[1:]) {
return nil, ErrMissingPrefix
}
input = input[3 : len(input)-1]
if len(input)%2 != 0 {
return nil, ErrOddLength
}
return input, nil
}
func checkNumberJSON(input []byte) (raw []byte, err error) {
if !isString(input) {
return nil, errNonString
}
input = input[1 : len(input)-1]
if len(input) == 0 {
return nil, nil // empty strings are allowed
}
if !bytesHave0xPrefix(input) {
return nil, ErrMissingPrefix
}
input = input[2:]
if len(input) == 0 {
return nil, ErrEmptyNumber
}
if len(input) > 1 && input[0] == '0' {
return nil, ErrLeadingZero
}
return input, nil
}
