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forked from um/cli

refactor: rework on MusicEx footer parser

This commit is contained in:
鲁树人 2024-07-06 20:32:26 +01:00
parent e010d1b308
commit 68e0c06246
3 changed files with 77 additions and 49 deletions

View File

@ -98,6 +98,7 @@ func OpenMMKV(mmkvPath string, key string, logger *zap.Logger) error {
return nil
}
// /
func readKeyFromMMKVCustom(mid string) ([]byte, error) {
if streamKeyVault == nil {
return nil, fmt.Errorf("mmkv vault not loaded")

View File

@ -145,13 +145,12 @@ func (d *Decoder) searchKey() (err error) {
case "STag":
return errors.New("qmc: file with 'STag' suffix doesn't contains media key")
case "cex\x00":
footer := qqMusicTagMusicEx{}
audioLen, err := footer.Read(d.raw)
footer, err := NewMusicExTag(d.raw)
if err != nil {
return err
}
d.audioLen = int(audioLen)
d.decodedKey, err = readKeyFromMMKVCustom(footer.mediafile)
d.audioLen = fileSize - int(footer.TagSize)
d.decodedKey, err = readKeyFromMMKVCustom(footer.MediaFileName)
if err != nil {
return err
}

View File

@ -1,65 +1,93 @@
package qmc
import (
bytes "bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"strings"
)
type qqMusicTagMusicEx struct {
songid uint32 // Song ID
unknown_1 uint32 // unused & unknown
unknown_2 uint32 // unused & unknown
mid string // Media ID
mediafile string // real file name
unknown_3 uint32 // unused; uninitialized memory?
sizeof_struct uint32 // 19.57: fixed value: 0xC0
version uint32 // 19.57: fixed value: 0x01
tag_magic []byte // fixed value "musicex\0" (8 bytes)
type MusicExTagV1 struct {
SongID uint32 // Song ID
Unknown1 uint32 // unused & unknown
Unknown2 uint32 // unused & unknown
MediaID string // Media ID
MediaFileName string // real file name
Unknown3 uint32 // unused; uninitialized memory?
// 16 byte at the end of tag.
// TagSize should be respected when parsing.
TagSize uint32 // 19.57: fixed value: 0xC0
TagVersion uint32 // 19.57: fixed value: 0x01
TagMagic []byte // fixed value "musicex\0" (8 bytes)
}
func (tag *qqMusicTagMusicEx) Read(raw io.ReadSeeker) (int64, error) {
_, err := raw.Seek(-16, io.SeekEnd)
func NewMusicExTag(f io.ReadSeeker) (*MusicExTagV1, error) {
_, err := f.Seek(-16, io.SeekEnd)
if err != nil {
return 0, fmt.Errorf("musicex seek error: %w", err)
return nil, fmt.Errorf("musicex seek error: %w", err)
}
footerBuf := make([]byte, 4)
footerBuf, err = io.ReadAll(io.LimitReader(raw, 4))
buffer := make([]byte, 16)
bytesRead, err := f.Read(buffer)
if err != nil {
return 0, fmt.Errorf("get musicex error: %w", err)
return nil, fmt.Errorf("get musicex error: %w", err)
}
if bytesRead != 16 {
return nil, fmt.Errorf("MusicExV1: read %d bytes (expected %d)", bytesRead, 16)
}
footerLen := int64(binary.LittleEndian.Uint32(footerBuf))
audioLen, err := raw.Seek(-footerLen, io.SeekEnd)
buf, err := io.ReadAll(io.LimitReader(raw, audioLen))
tag := &MusicExTagV1{
TagSize: binary.LittleEndian.Uint32(buffer[0x00:0x04]),
TagVersion: binary.LittleEndian.Uint32(buffer[0x04:0x08]),
TagMagic: buffer[0x04:0x0C],
}
if !bytes.Equal(tag.TagMagic, []byte("musicex\x00")) {
return nil, errors.New("MusicEx magic mismatch")
}
if tag.TagVersion != 1 {
return nil, errors.New(fmt.Sprintf("unsupported musicex tag version. expecting 1, got %d", tag.TagVersion))
}
if tag.TagSize < 0xC0 {
return nil, errors.New(fmt.Sprintf("unsupported musicex tag size. expecting at least 0xC0, got 0x%02x", tag.TagSize))
}
buffer = make([]byte, tag.TagSize)
bytesRead, err = f.Read(buffer)
if err != nil {
return 0, err
return nil, err
}
if uint32(bytesRead) != tag.TagSize {
return nil, fmt.Errorf("MusicExV1: read %d bytes (expected %d)", bytesRead, tag.TagSize)
}
tag.songid = binary.LittleEndian.Uint32(buf[0:4])
tag.unknown_1 = binary.LittleEndian.Uint32(buf[4:8])
tag.unknown_2 = binary.LittleEndian.Uint32(buf[8:12])
tag.SongID = binary.LittleEndian.Uint32(buffer[0x00:0x04])
tag.Unknown1 = binary.LittleEndian.Uint32(buffer[0x04:0x08])
tag.Unknown2 = binary.LittleEndian.Uint32(buffer[0x08:0x0C])
tag.MediaID = readUnicodeTagName(buffer[0x0C:], 30*2)
tag.MediaFileName = readUnicodeTagName(buffer[0x48:], 50*2)
tag.Unknown3 = binary.LittleEndian.Uint32(buffer[0xAC:0xB0])
return tag, nil
}
for i := 0; i < 30; i++ {
u := binary.LittleEndian.Uint16(buf[12+i*2 : 12+(i+1)*2])
if u == 0 {
// readUnicodeTagName reads a buffer to maxLen.
// reconstruct text by skipping alternate char (ascii chars encoded in UTF-16-LE),
// until finding a zero or reaching maxLen.
func readUnicodeTagName(buffer []byte, maxLen int) string {
builder := strings.Builder{}
for i := 0; i < maxLen; i += 2 {
chr := buffer[i]
if chr != 0 {
builder.WriteByte(chr)
} else {
break
}
tag.mid += string(u)
}
for i := 0; i < 50; i++ {
u := binary.LittleEndian.Uint16(buf[72+i*2 : 72+(i+1)*2])
if u == 0 {
break
}
tag.mediafile += string(u)
}
tag.unknown_3 = binary.LittleEndian.Uint32(buf[173:177])
tag.sizeof_struct = binary.LittleEndian.Uint32(buf[177:181])
tag.version = binary.LittleEndian.Uint32(buf[181:185])
tag.tag_magic = buf[185:193]
return audioLen, nil
return builder.String()
}