path: root/common/bytes.go

// Copyright 2014 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 common contains various helper functions.
package common

import (
    "bytes"
    "encoding/binary"
    "encoding/hex"
    "fmt"
    "math/big"
    "strings"
)

func ToHex(b []byte) string {
    hex := Bytes2Hex(b)
    // Prefer output of "0x0" instead of "0x"
    if len(hex) == 0 {
        hex = "0"
    }
    return "0x" + hex
}

func FromHex(s string) []byte {
    if len(s) > 1 {
        if s[0:2] == "0x" {
            s = s[2:]
        }
        if len(s)%2 == 1 {
            s = "0" + s
        }
        return Hex2Bytes(s)
    }
    return nil
}

type Bytes []byte

func (self Bytes) String() string {
    return string(self)
}

func DeleteFromByteSlice(s [][]byte, hash []byte) [][]byte {
    for i, h := range s {
        if bytes.Compare(h, hash) == 0 {
            return append(s[:i:i], s[i+1:]...)
        }
    }

    return s
}

// Number to bytes
//
// Returns the number in bytes with the specified base
func NumberToBytes(num interface{}, bits int) []byte {
    buf := new(bytes.Buffer)
    err := binary.Write(buf, binary.BigEndian, num)
    if err != nil {
        fmt.Println("NumberToBytes failed:", err)
    }

    return buf.Bytes()[buf.Len()-(bits/8):]
}

// Bytes to number
//
// Attempts to cast a byte slice to a unsigned integer
func BytesToNumber(b []byte) uint64 {
    var number uint64

    // Make sure the buffer is 64bits
    data := make([]byte, 8)
    data = append(data[:len(b)], b...)

    buf := bytes.NewReader(data)
    err := binary.Read(buf, binary.BigEndian, &number)
    if err != nil {
        fmt.Println("BytesToNumber failed:", err)
    }

    return number
}

// Read variable int
//
// Read a variable length number in big endian byte order
func ReadVarInt(buff []byte) (ret uint64) {
    switch l := len(buff); {
    case l > 4:
        d := LeftPadBytes(buff, 8)
        binary.Read(bytes.NewReader(d), binary.BigEndian, &ret)
    case l > 2:
        var num uint32
        d := LeftPadBytes(buff, 4)
        binary.Read(bytes.NewReader(d), binary.BigEndian, &num)
        ret = uint64(num)
    case l > 1:
        var num uint16
        d := LeftPadBytes(buff, 2)
        binary.Read(bytes.NewReader(d), binary.BigEndian, &num)
        ret = uint64(num)
    default:
        var num uint8
        binary.Read(bytes.NewReader(buff), binary.BigEndian, &num)
        ret = uint64(num)
    }

    return
}

// Copy bytes
//
// Returns an exact copy of the provided bytes
func CopyBytes(b []byte) (copiedBytes []byte) {
    copiedBytes = make([]byte, len(b))
    copy(copiedBytes, b)

    return
}

func HasHexPrefix(str string) bool {
    l := len(str)
    return l >= 2 && str[0:2] == "0x"
}

func IsHex(str string) bool {
    l := len(str)
    return l >= 4 && l%2 == 0 && str[0:2] == "0x"
}

func Bytes2Hex(d []byte) string {
    return hex.EncodeToString(d)
}

func Hex2Bytes(str string) []byte {
    h, _ := hex.DecodeString(str)

    return h
}

func Hex2BytesFixed(str string, flen int) []byte {
    h, _ := hex.DecodeString(str)
    if len(h) == flen {
        return h
    } else {
        if len(h) > flen {
            return h[len(h)-flen : len(h)]
        } else {
            hh := make([]byte, flen)
            copy(hh[flen-len(h):flen], h[:])
            return hh
        }
    }
}

func StringToByteFunc(str string, cb func(str string) []byte) (ret []byte) {
    if len(str) > 1 && str[0:2] == "0x" && !strings.Contains(str, "\n") {
        ret = Hex2Bytes(str[2:])
    } else {
        ret = cb(str)
    }

    return
}

func FormatData(data string) []byte {
    if len(data) == 0 {
        return nil
    }
    // Simple stupid
    d := new(big.Int)
    if data[0:1] == "\"" && data[len(data)-1:] == "\"" {
        return RightPadBytes([]byte(data[1:len(data)-1]), 32)
    } else if len(data) > 1 && data[:2] == "0x" {
        d.SetBytes(Hex2Bytes(data[2:]))
    } else {
        d.SetString(data, 0)
    }

    return BigToBytes(d, 256)
}

func ParseData(data ...interface{}) (ret []byte) {
    for _, item := range data {
        switch t := item.(type) {
        case string:
            var str []byte
            if IsHex(t) {
                str = Hex2Bytes(t[2:])
            } else {
                str = []byte(t)
            }

            ret = append(ret, RightPadBytes(str, 32)...)
        case []byte:
            ret = append(ret, LeftPadBytes(t, 32)...)
        }
    }

    return
}

func RightPadBytes(slice []byte, l int) []byte {
    if l < len(slice) {
        return slice
    }

    padded := make([]byte, l)
    copy(padded[0:len(slice)], slice)

    return padded
}

func LeftPadBytes(slice []byte, l int) []byte {
    if l < len(slice) {
        return slice
    }

    padded := make([]byte, l)
    copy(padded[l-len(slice):], slice)

    return padded
}

func LeftPadString(str string, l int) string {
    if l < len(str) {
        return str
    }

    zeros := Bytes2Hex(make([]byte, (l-len(str))/2))

    return zeros + str

}

func RightPadString(str string, l int) string {
    if l < len(str) {
        return str
    }

    zeros := Bytes2Hex(make([]byte, (l-len(str))/2))

    return str + zeros

}

func ToAddress(slice []byte) (addr []byte) {
    if len(slice) < 20 {
        addr = LeftPadBytes(slice, 20)
    } else if len(slice) > 20 {
        addr = slice[len(slice)-20:]
    } else {
        addr = slice
    }

    addr = CopyBytes(addr)

    return
}

func ByteSliceToInterface(slice [][]byte) (ret []interface{}) {
    for _, i := range slice {
        ret = append(ret, i)
    }

    return
}