1 files changed, 271 insertions, 0 deletions
diff --git a/common/hexutil/json.go b/common/hexutil/json.go
new file mode 100644
index 000000000..cbbadbed6
--- /dev/null
+++ b/common/hexutil/json.go
@@ -0,0 +1,271 @@
+// 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 := make([]byte, 3, (nbits/8)*2+4)
+	copy(enc, `"0x`)
+	for i := len(bigint.Bits()) - 1; i >= 0; i-- {
+		enc = strconv.AppendUint(enc, uint64(bigint.Bits()[i]), 16)
+	}
+	enc = append(enc, '"')
+	return 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, ErrEmptyString
+	}
+	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, ErrEmptyString
+	}
+	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
+}