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