path: root/ethutil/bytes.go

package ethutil

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

// 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(reader *bytes.Reader) (ret uint64) {
    if reader.Len() == 8 {
        var num uint64
        binary.Read(reader, binary.BigEndian, &num)
        ret = uint64(num)
    } else if reader.Len() == 4 {
        var num uint32
        binary.Read(reader, binary.BigEndian, &num)
        ret = uint64(num)
    } else if reader.Len() == 2 {
        var num uint16
        binary.Read(reader, binary.BigEndian, &num)
        ret = uint64(num)
    } else {
        var num uint8
        binary.Read(reader, binary.BigEndian, &num)
        ret = uint64(num)
    }

    return ret
}

// Binary length
//
// Returns the true binary length of the given number
func BinaryLength(num int) int {
    if num == 0 {
        return 0
    }

    return 1 + BinaryLength(num>>8)
}

// 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 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 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), 32)
    } else if len(data) > 1 && data[:2] == "0x" {
        d.SetBytes(Hex2Bytes(data[2:]))
    } else {
        d.SetString(data, 0)
    }

    return BigToBytes(d, 256)
}

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 Address(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
}