feat: mmkv 加密数据库解析

algo/qmc/key_mmkv.go

@@ -1,17 +1,20 @@
 package qmc
 
 import (
+	"bytes"
+	"encoding/base64"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"runtime"
 
+	"git.unlock-music.dev/awalol/go-mmkv"
 	"github.com/samber/lo"
 	"go.uber.org/zap"
 	"golang.org/x/exp/slices"
 	"golang.org/x/text/unicode/norm"
-	"unlock-music.dev/mmkv"
 )
 
 var streamKeyVault mmkv.Vault
@@ -80,6 +83,45 @@ func readKeyFromMMKV(file string, logger *zap.Logger) ([]byte, error) {
 	return deriveKey(buf)
 }
 
+func readKeyFromMMKVCustom(d *Decoder) ([]byte, error) {
+	logger := d.logger
+	filePath, fileName := filepath.Split(VaultPath)
+
+	if streamKeyVault == nil {
+		mgr, err := mmkv.NewManager(filepath.Dir(filePath))
+		if err != nil {
+			return nil, fmt.Errorf("init mmkv manager: %w", err)
+		}
+
+		streamKeyVault, err = mgr.OpenVaultCrypto(fileName, VaultKey)
+		if err != nil {
+			return nil, fmt.Errorf("open mmkv vault: %w", err)
+		}
+
+		logger.Debug("mmkv vault opened", zap.Strings("keys", streamKeyVault.Keys()))
+	}
+
+	// 获取mid即数据库键值
+	_, err := d.raw.Seek(-128, io.SeekEnd)
+	if err != nil {
+		return nil, fmt.Errorf("get mid error: %w", err)
+	}
+	mid, err := io.ReadAll(io.LimitReader(d.raw, 64))   // 取64字节确保完全取完
+	mid = bytes.ReplaceAll(mid, []byte{0x00}, []byte{}) // clean NUL
+	mid = bytes.Trim(mid, "\0000")                      // maybe a little stupid
+
+	// 从数据库获取eKey
+	eKey, err := streamKeyVault.GetBytes(string(mid))
+	if err != nil {
+		return nil, fmt.Errorf("get eKey error: %w", err)
+	}
+	n, err := base64.StdEncoding.Decode(eKey, eKey)
+	if err != nil {
+		return nil, fmt.Errorf("base64 error: %w", err)
+	}
+	return deriveKeyV1(eKey[:n])
+}
+
 func getRelativeMMKVDir(file string) (string, error) {
 	mmkvDir := filepath.Join(filepath.Dir(file), "../mmkv")
 	if _, err := os.Stat(mmkvDir); err != nil {

algo/qmc/qmc.go

@@ -16,6 +16,9 @@ import (
 	"unlock-music.dev/cli/internal/sniff"
 )
 
+var VaultPath = ""
+var VaultKey = ""
+
 type Decoder struct {
 	raw    io.ReadSeeker // raw is the original file reader
 	params *common.DecoderParams
@@ -140,11 +143,32 @@ func (d *Decoder) searchKey() (err error) {
 		return err
 	}
 
-	switch string(suffixBuf) {
+	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)