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unlock-music-cli/algo/kgm/kgm.go

79 lines
1.5 KiB
Go

package kgm
import (
"bytes"
"fmt"
"io"
"github.com/unlock-music/cli/algo/common"
)
type Decoder struct {
header Header
initializer kgmCryptoInitializer
file []byte
audio []byte
}
type kgmCryptoInitializer func(header *Header, body io.Reader) (io.Reader, error)
var kgmCryptoInitializers = map[uint32]kgmCryptoInitializer{
3: newKgmCryptoV3,
}
func NewDecoder(file []byte) common.Decoder {
return &Decoder{
file: file,
}
}
func (d *Decoder) GetAudioData() []byte {
return d.audio
}
func (d *Decoder) GetAudioExt() string {
return "" // use sniffer
}
func (d *Decoder) GetMeta() common.Meta {
return nil
}
func (d *Decoder) Validate() error {
if err := d.header.FromBytes(d.file); err != nil {
return err
}
// TODO; validate crypto version
var ok bool
d.initializer, ok = kgmCryptoInitializers[d.header.CryptoVersion]
if !ok {
return fmt.Errorf("kgm: unsupported crypto version %d", d.header.CryptoVersion)
}
return nil
}
func (d *Decoder) Decode() error {
d.audio = d.file[d.header.AudioOffset:]
r, err := d.initializer(&d.header, bytes.NewReader(d.audio))
if err != nil {
return fmt.Errorf("kgm: failed to initialize crypto: %w", err)
}
d.audio, err = io.ReadAll(r)
if err != nil {
return fmt.Errorf("kgm: failed to decrypt audio: %w", err)
}
return nil
}
func init() {
// Kugou
common.RegisterDecoder("kgm", false, NewDecoder)
common.RegisterDecoder("kgma", false, NewDecoder)
// Viper
common.RegisterDecoder("vpr", false, NewDecoder)
}