You cannot select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
unlock-music-cli/algo/qmc/qmc.go

277 lines
6.4 KiB
Go

This file contains ambiguous Unicode characters!

This file contains ambiguous Unicode characters that may be confused with others in your current locale. If your use case is intentional and legitimate, you can safely ignore this warning. Use the Escape button to highlight these characters.

package qmc
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"runtime"
"strconv"
"strings"
"go.uber.org/zap"
"unlock-music.dev/cli/algo/common"
"unlock-music.dev/cli/internal/sniff"
)
type Decoder struct {
raw io.ReadSeeker // raw is the original file reader
params *common.DecoderParams
audio io.Reader // audio is the encrypted audio data
audioLen int // audioLen is the audio data length
offset int // offset is the current audio read position
decodedKey []byte // decodedKey is the decoded key for cipher
cipher common.StreamDecoder
songID int
rawMetaExtra2 int
albumID int
albumMediaID string
// cache
meta common.AudioMeta
cover []byte
embeddedCover bool // embeddedCover is true if the cover is embedded in the file
probeBuf *bytes.Buffer // probeBuf is the buffer for sniffing metadata, TODO: consider pipe?
// provider
logger *zap.Logger
}
// Read implements io.Reader, offer the decrypted audio data.
// Validate should call before Read to check if the file is valid.
func (d *Decoder) Read(p []byte) (int, error) {
n, err := d.audio.Read(p)
if n > 0 {
d.cipher.Decrypt(p[:n], d.offset)
d.offset += n
_, _ = d.probeBuf.Write(p[:n]) // bytes.Buffer.Write never return error
}
return n, err
}
func NewDecoder(p *common.DecoderParams) common.Decoder {
return &Decoder{raw: p.Reader, params: p, logger: p.Logger}
}
func (d *Decoder) Validate() error {
// search & derive key
err := d.searchKey()
if err != nil {
return err
}
// check cipher type and init decode cipher
if len(d.decodedKey) > 300 {
d.cipher, err = newRC4Cipher(d.decodedKey)
if err != nil {
return err
}
} else if len(d.decodedKey) != 0 {
d.cipher, err = newMapCipher(d.decodedKey)
if err != nil {
return err
}
} else {
d.cipher = newStaticCipher()
}
// test with first 16 bytes
if err := d.validateDecode(); err != nil {
return err
}
// reset position, limit to audio, prepare for Read
if _, err := d.raw.Seek(0, io.SeekStart); err != nil {
return err
}
d.audio = io.LimitReader(d.raw, int64(d.audioLen))
// prepare for sniffing metadata
d.probeBuf = bytes.NewBuffer(make([]byte, 0, d.audioLen))
return nil
}
func (d *Decoder) validateDecode() error {
_, err := d.raw.Seek(0, io.SeekStart)
if err != nil {
return fmt.Errorf("qmc seek to start: %w", err)
}
buf := make([]byte, 64)
if _, err := io.ReadFull(d.raw, buf); err != nil {
return fmt.Errorf("qmc read header: %w", err)
}
d.cipher.Decrypt(buf, 0)
_, ok := sniff.AudioExtension(buf)
if !ok {
return errors.New("qmc: detect file type failed")
}
return nil
}
func (d *Decoder) searchKey() (err error) {
fileSizeM4, err := d.raw.Seek(-4, io.SeekEnd)
if err != nil {
return err
}
fileSize := int(fileSizeM4) + 4
//goland:noinspection GoBoolExpressions
if runtime.GOOS == "darwin" && !strings.HasPrefix(d.params.Extension, ".qmc") {
d.decodedKey, err = readKeyFromMMKV(d.params.FilePath, d.logger)
if err == nil {
d.audioLen = fileSize
return
}
d.logger.Warn("read key from mmkv failed", zap.Error(err))
}
suffixBuf := make([]byte, 4)
if _, err := io.ReadFull(d.raw, suffixBuf); err != nil {
return err
}
switch string(bytes.ReplaceAll(suffixBuf, []byte{0x00}, []byte{})) {
case "QTag":
return d.readRawMetaQTag()
case "STag":
return errors.New("qmc: file with 'STag' suffix doesn't contains media key")
case "cex":
d.decodedKey, err = readKeyFromMMKVCustom(d)
if err == nil {
suffix := []byte{0x63, 0x65, 0x78, 0x00} // cex
for i := 0; i <= 3; i++ {
// 末尾的信息数据每192字节出现一次故只要循环判断末尾不为musicex时即为歌曲数据
musicexLen, err := d.raw.Seek(int64(-(192*i)-4), io.SeekEnd)
if err != nil {
return fmt.Errorf("get musicexLen error: %w", err)
}
buf, err := io.ReadAll(io.LimitReader(d.raw, 4))
if err != nil {
return fmt.Errorf("get musicex error: %w", err)
}
if !bytes.Equal(buf, suffix) {
d.audioLen = int(musicexLen) + 4
return nil
}
}
}
return err
default:
size := binary.LittleEndian.Uint32(suffixBuf)
if size <= 0xFFFF && size != 0 { // assume size is key len
return d.readRawKey(int64(size))
}
// try to use default static cipher
d.audioLen = fileSize
return nil
}
}
func (d *Decoder) readRawKey(rawKeyLen int64) error {
audioLen, err := d.raw.Seek(-(4 + rawKeyLen), io.SeekEnd)
if err != nil {
return err
}
d.audioLen = int(audioLen)
rawKeyData, err := io.ReadAll(io.LimitReader(d.raw, rawKeyLen))
if err != nil {
return err
}
// clean suffix NULs
rawKeyData = bytes.TrimRight(rawKeyData, "\x00")
d.decodedKey, err = deriveKey(rawKeyData)
if err != nil {
return err
}
return nil
}
func (d *Decoder) readRawMetaQTag() error {
// get raw meta data len
if _, err := d.raw.Seek(-8, io.SeekEnd); err != nil {
return err
}
buf, err := io.ReadAll(io.LimitReader(d.raw, 4))
if err != nil {
return err
}
rawMetaLen := int64(binary.BigEndian.Uint32(buf))
// read raw meta data
audioLen, err := d.raw.Seek(-(8 + rawMetaLen), io.SeekEnd)
if err != nil {
return err
}
d.audioLen = int(audioLen)
rawMetaData, err := io.ReadAll(io.LimitReader(d.raw, rawMetaLen))
if err != nil {
return err
}
items := strings.Split(string(rawMetaData), ",")
if len(items) != 3 {
return errors.New("invalid raw meta data")
}
d.decodedKey, err = deriveKey([]byte(items[0]))
if err != nil {
return err
}
d.songID, err = strconv.Atoi(items[1])
if err != nil {
return err
}
d.rawMetaExtra2, err = strconv.Atoi(items[2])
if err != nil {
return err
}
return nil
}
//goland:noinspection SpellCheckingInspection
func init() {
supportedExts := []string{
"qmc0", "qmc3", //QQ Music MP3
"qmc2", "qmc4", "qmc6", "qmc8", //QQ Music M4A
"qmcflac", //QQ Music FLAC
"qmcogg", //QQ Music OGG
"tkm", //QQ Music Accompaniment M4A
"bkcmp3", "bkcm4a", "bkcflac", "bkcwav", "bkcape", "bkcogg", "bkcwma", //Moo Music
"666c6163", //QQ Music Weiyun Flac
"6d7033", //QQ Music Weiyun Mp3
"6f6767", //QQ Music Weiyun Ogg
"6d3461", //QQ Music Weiyun M4a
"776176", //QQ Music Weiyun Wav
"mgg", "mgg1", "mggl", //QQ Music New Ogg
"mflac", "mflac0", "mflach", //QQ Music New Flac
"mmp4", // QQ Music MP4 Container, tipically used for Dolby EAC3 stream
}
for _, ext := range supportedExts {
common.RegisterDecoder(ext, false, NewDecoder)
}
}