From db85f600230eadbe7cb9048ca9de8ad92dae71bf Mon Sep 17 00:00:00 2001 From: Emmm Monster <58943012+emmmx@users.noreply.github.com> Date: Sat, 26 Dec 2020 00:49:03 +0800 Subject: [PATCH] Update NCM Decoder --- algo/common/common.go | 3 +- algo/ncm/ncm.go | 146 +++++++++++++++++++++--------------------- 2 files changed, 75 insertions(+), 74 deletions(-) diff --git a/algo/common/common.go b/algo/common/common.go index bfbe5d5..1b8bea9 100644 --- a/algo/common/common.go +++ b/algo/common/common.go @@ -1,11 +1,12 @@ package common type Decoder interface { + Validate() bool Decode() error GetCoverImage() []byte GetAudioData() []byte GetAudioExt() string - GetMeta() *Meta + GetMeta() Meta } type Meta interface { diff --git a/algo/ncm/ncm.go b/algo/ncm/ncm.go index 4d2f8ba..2687bc6 100644 --- a/algo/ncm/ncm.go +++ b/algo/ncm/ncm.go @@ -28,14 +28,14 @@ var ( func NewDecoder(data []byte) *Decoder { return &Decoder{ - data: data, - fileLength: uint32(len(data)), + file: data, + fileLen: uint32(len(data)), } } type Decoder struct { - data []byte - fileLength uint32 + file []byte + fileLen uint32 key []byte box []byte @@ -53,51 +53,51 @@ type Decoder struct { offsetAudio uint32 } -func (f *Decoder) Validate() bool { - if !bytes.Equal(magicHeader, f.data[:len(magicHeader)]) { +func (d *Decoder) Validate() bool { + if !bytes.Equal(magicHeader, d.file[:len(magicHeader)]) { return false } /*if status.IsDebug { - logging.Log().Info("the unknown field of the header is: \n" + spew.Sdump(f.data[8:10])) + logging.Log().Info("the unknown field of the header is: \n" + spew.Sdump(d.file[8:10])) }*/ - f.offsetKey = 8 + 2 + d.offsetKey = 8 + 2 return true } //todo: 读取前进行检查长度，防止越界 -func (f *Decoder) readKeyData() error { - if f.offsetKey == 0 || f.offsetKey+4 > f.fileLength { - return errors.New("invalid cover data offset") +func (d *Decoder) readKeyData() error { + if d.offsetKey == 0 || d.offsetKey+4 > d.fileLen { + return errors.New("invalid cover file offset") } - bKeyLen := f.data[f.offsetKey : f.offsetKey+4] + bKeyLen := d.file[d.offsetKey : d.offsetKey+4] iKeyLen := binary.LittleEndian.Uint32(bKeyLen) - f.offsetMeta = f.offsetKey + 4 + iKeyLen + d.offsetMeta = d.offsetKey + 4 + iKeyLen bKeyRaw := make([]byte, iKeyLen) for i := uint32(0); i < iKeyLen; i++ { - bKeyRaw[i] = f.data[i+4+f.offsetKey] ^ 0x64 + bKeyRaw[i] = d.file[i+4+d.offsetKey] ^ 0x64 } - f.key = utils.PKCS7UnPadding(utils.DecryptAes128Ecb(bKeyRaw, keyCore))[17:] + d.key = utils.PKCS7UnPadding(utils.DecryptAes128Ecb(bKeyRaw, keyCore))[17:] return nil } -func (f *Decoder) readMetaData() error { - if f.offsetMeta == 0 || f.offsetMeta+4 > f.fileLength { - return errors.New("invalid meta data offset") +func (d *Decoder) readMetaData() error { + if d.offsetMeta == 0 || d.offsetMeta+4 > d.fileLen { + return errors.New("invalid meta file offset") } - bMetaLen := f.data[f.offsetMeta : f.offsetMeta+4] + bMetaLen := d.file[d.offsetMeta : d.offsetMeta+4] iMetaLen := binary.LittleEndian.Uint32(bMetaLen) - f.offsetCover = f.offsetMeta + 4 + iMetaLen + d.offsetCover = d.offsetMeta + 4 + iMetaLen if iMetaLen == 0 { - return errors.New("no any meta data found") + return errors.New("no any meta file found") } // Why sub 22: Remove "163 key(Don't modify):" bKeyRaw := make([]byte, iMetaLen-22) for i := uint32(0); i < iMetaLen-22; i++ { - bKeyRaw[i] = f.data[f.offsetMeta+4+22+i] ^ 0x63 + bKeyRaw[i] = d.file[d.offsetMeta+4+22+i] ^ 0x63 } cipherText, err := base64.StdEncoding.DecodeString(string(bKeyRaw)) @@ -107,129 +107,129 @@ func (f *Decoder) readMetaData() error { metaRaw := utils.PKCS7UnPadding(utils.DecryptAes128Ecb(cipherText, keyMeta)) sepIdx := bytes.IndexRune(metaRaw, ':') if sepIdx == -1 { - return errors.New("invalid ncm meta data") + return errors.New("invalid ncm meta file") } - f.metaType = string(metaRaw[:sepIdx]) - f.metaRaw = metaRaw[sepIdx+1:] + d.metaType = string(metaRaw[:sepIdx]) + d.metaRaw = metaRaw[sepIdx+1:] return nil } -func (f *Decoder) buildKeyBox() { +func (d *Decoder) buildKeyBox() { box := make([]byte, 256) for i := 0; i < 256; i++ { box[i] = byte(i) } - keyLen := len(f.key) + keyLen := len(d.key) var j byte for i := 0; i < 256; i++ { - j = box[i] + j + f.key[i%keyLen] + j = box[i] + j + d.key[i%keyLen] box[i], box[j] = box[j], box[i] } - f.box = make([]byte, 256) + d.box = make([]byte, 256) var _i byte for i := 0; i < 256; i++ { _i = byte(i + 1) si := box[_i] sj := box[_i+si] - f.box[i] = box[si+sj] + d.box[i] = box[si+sj] } } -func (f *Decoder) parseMeta() error { - switch f.metaType { +func (d *Decoder) parseMeta() error { + switch d.metaType { case "music": - f.Meta = new(RawMetaMusic) - return json.Unmarshal(f.metaRaw, f.Meta) + d.Meta = new(RawMetaMusic) + return json.Unmarshal(d.metaRaw, d.Meta) case "dj": - f.Meta = new(RawMetaDJ) + d.Meta = new(RawMetaDJ) + return json.Unmarshal(d.metaRaw, d.Meta) default: - return errors.New("unknown ncm meta type: " + f.metaType) + return errors.New("unknown ncm meta type: " + d.metaType) } - return nil } -func (f *Decoder) readCoverData() error { - if f.offsetCover == 0 || f.offsetCover+13 > f.fileLength { - return errors.New("invalid cover data offset") +func (d *Decoder) readCoverData() error { + if d.offsetCover == 0 || d.offsetCover+13 > d.fileLen { + return errors.New("invalid cover file offset") } - coverLenStart := f.offsetCover + 5 + 4 - bCoverLen := f.data[coverLenStart : coverLenStart+4] + coverLenStart := d.offsetCover + 5 + 4 + bCoverLen := d.file[coverLenStart : coverLenStart+4] /*if status.IsDebug { logging.Log().Info("the unknown field of the cover is: \n" + - spew.Sdump(f.data[f.offsetCover:f.offsetCover+5])) - coverLen2 := f.data[f.offsetCover+5 : f.offsetCover+5+4] // it seems that always the same + spew.Sdump(d.file[d.offsetCover:d.offsetCover+5])) + coverLen2 := d.file[d.offsetCover+5 : d.offsetCover+5+4] // it seems that always the same if !bytes.Equal(coverLen2, bCoverLen) { logging.Log().Warn("special file found! 2 cover length filed no the same!") } }*/ iCoverLen := binary.LittleEndian.Uint32(bCoverLen) - f.offsetAudio = coverLenStart + 4 + iCoverLen + d.offsetAudio = coverLenStart + 4 + iCoverLen if iCoverLen == 0 { - return errors.New("no any cover data found") + return errors.New("no any cover file found") } - f.Cover = f.data[coverLenStart+4 : 4+coverLenStart+iCoverLen] + d.Cover = d.file[coverLenStart+4 : 4+coverLenStart+iCoverLen] return nil } -func (f *Decoder) readAudioData() error { - if f.offsetAudio == 0 || f.offsetAudio > f.fileLength { +func (d *Decoder) readAudioData() error { + if d.offsetAudio == 0 || d.offsetAudio > d.fileLen { return errors.New("invalid audio offset") } - audioRaw := f.data[f.offsetAudio:] + audioRaw := d.file[d.offsetAudio:] audioLen := len(audioRaw) - f.Audio = make([]byte, audioLen) + d.Audio = make([]byte, audioLen) for i := uint32(0); i < uint32(audioLen); i++ { - f.Audio[i] = f.box[i&0xff] ^ audioRaw[i] + d.Audio[i] = d.box[i&0xff] ^ audioRaw[i] } return nil } -func (f *Decoder) Decode() error { - if err := f.readKeyData(); err != nil { +func (d *Decoder) Decode() error { + if err := d.readKeyData(); err != nil { return err } - f.buildKeyBox() + d.buildKeyBox() - err := f.readMetaData() + err := d.readMetaData() if err == nil { - err = f.parseMeta() + err = d.parseMeta() } if err != nil { - logging.Log().Warn("parse ncm meta data failed", zap.Error(err)) + logging.Log().Warn("parse ncm meta file failed", zap.Error(err)) } - err = f.readCoverData() + err = d.readCoverData() if err != nil { - logging.Log().Warn("parse ncm cover data failed", zap.Error(err)) + logging.Log().Warn("parse ncm cover file failed", zap.Error(err)) } - return f.readAudioData() + return d.readAudioData() } -func (f Decoder) GetAudioExt() string { - if f.Meta != nil { - return f.Meta.GetFormat() +func (d Decoder) GetAudioExt() string { + if d.Meta != nil { + return d.Meta.GetFormat() } return "" } -func (f Decoder) GetAudioData() []byte { - return f.Audio +func (d Decoder) GetAudioData() []byte { + return d.Audio } -func (f Decoder) GetCoverImage() []byte { - if f.Cover != nil { - return f.Cover +func (d Decoder) GetCoverImage() []byte { + if d.Cover != nil { + return d.Cover } { - imgURL := f.Meta.GetAlbumImageURL() - if f.Meta != nil && !strings.HasPrefix(imgURL, "http") { + imgURL := d.Meta.GetAlbumImageURL() + if d.Meta != nil && !strings.HasPrefix(imgURL, "http") { return nil } resp, err := http.Get(imgURL) @@ -252,6 +252,6 @@ func (f Decoder) GetCoverImage() []byte { } } -func (f Decoder) GetMeta() common.Meta { - return f.Meta +func (d Decoder) GetMeta() common.Meta { + return d.Meta }