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extended_uuid.go
132 lines (115 loc) · 3.1 KB
/
extended_uuid.go
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package extended_uuid
import (
"encoding/binary"
"encoding/hex"
"errors"
"github.com/google/uuid"
"hash/crc32"
"strings"
)
type ExUuid struct {
Uuid *uuid.UUID
additionalData []uint32
}
func Parse(exUuidText string, isLittleEndian bool) (*ExUuid, error) {
var exUuid ExUuid
uuidText := exUuidText[len(exUuidText) - 36:len(exUuidText)]
uuid, err := uuid.Parse(uuidText)
if err != nil {
return &exUuid, errors.New("fail to parse uuid")
}
data := exUuidText[0: len(exUuidText) - 37]
segments := strings.Split(data, "-")
for i := 0; i < len(segments); i++ {
segment := segments[i]
if len(segment) != 8 {
return &exUuid, errors.New("bad format for ExUuid")
}
bytes, err := hex.DecodeString(segment)
if err != nil {
return &exUuid, errors.New("bad format for ExUuid")
}
if isLittleEndian {
exUuid.additionalData = append(exUuid.additionalData, binary.BigEndian.Uint32(bytes))
} else {
exUuid.additionalData = append(exUuid.additionalData, binary.LittleEndian.Uint32(bytes))
}
}
exUuid.Uuid = &uuid
return &exUuid, nil
}
type ExUuidReader struct {
offset uint
bytes []byte
}
func (r *ExUuidReader) ReadByte() byte {
byte := r.bytes[r.offset]
r.offset = r.offset + 1
return byte
}
func NewExUuidReader(exUuid *ExUuid, isLittleEndian bool) *ExUuidReader {
var reader ExUuidReader
bytes, err := read(exUuid, isLittleEndian)
if err == nil {
reader.bytes = bytes
}
reader.offset = 0
return &reader
}
func reverseArray(array []byte) []byte {
var result []byte
for i := len(array) - 1; i >= 0; i-- {
result = append(result, array[i])
}
return result
}
func UuidToBytesArray(uuid *uuid.UUID) ([]byte, error) {
var result []byte
uuidBytes, err := uuid.MarshalBinary()
if err != nil {
return result, err
}
a := reverseArray(uuidBytes[0:4])
b := reverseArray(uuidBytes[4:6])
c := reverseArray(uuidBytes[6:8])
result = append(result, a[:]...)
result = append(result, b[:]...)
result = append(result, c[:]...)
result = append(result, uuidBytes[8:]...)
return result, nil
}
func read(exUuid *ExUuid, isLittleEndian bool) ([]byte, error) {
var bytes []byte
for i := 0; i < len(exUuid.additionalData); i++ {
cipher := exUuid.additionalData[i]
var byteStream []byte
for y := 0; y < i; y++ {
if isLittleEndian {
additionalDataBinary := make([]byte, 4)
binary.LittleEndian.PutUint32(additionalDataBinary, exUuid.additionalData[y])
byteStream = append(byteStream, additionalDataBinary[:]...)
} else {
additionalDataBinary := make([]byte, 4)
binary.BigEndian.PutUint32(additionalDataBinary, exUuid.additionalData[y])
byteStream = append(byteStream, additionalDataBinary[:]...)
}
}
uuidBytes, err := UuidToBytesArray(exUuid.Uuid)
if err != nil {
return byteStream, err
}
byteStream = append(byteStream, uuidBytes[:]...)
crc := crc32.NewIEEE()
crc.Write(byteStream)
key := crc.Sum32()
values := cipher ^ key
valueBytes := make([]byte, 4)
if isLittleEndian {
binary.LittleEndian.PutUint32(valueBytes, values)
} else {
binary.BigEndian.PutUint32(valueBytes, values)
}
bytes = append(bytes, valueBytes[:]...)
}
return bytes, nil
}