From 2fc9368a9241e2eca85378b8a99abcdfd1726842 Mon Sep 17 00:00:00 2001
From: MengYX <admin@mengyx.cn>
Date: Mon, 10 Feb 2020 20:06:59 +0800
Subject: [PATCH] Add Experimental Support For Mgg

---
 src/App.vue           |  2 +-
 src/decrypt/common.js |  4 +++
 src/decrypt/mgg.js    | 84 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+), 1 deletion(-)
 create mode 100644 src/decrypt/mgg.js

diff --git a/src/App.vue b/src/App.vue
index 32fa547..593d64e 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -75,7 +75,7 @@
                 this.$notify.info({
                     title: '离线使用',
                     message: '我们使用PWA技术，无网络也能使用<br/>' +
-                        '最近更新：支持bkcmp3/bkcflac/tkm<br/>' +
+                        '最近更新：提供实验性mgg支持<br/>' +
                         '点击查看 <a target="_blank" href="https://github.com/ix64/unlock-music/wiki/使用提示">使用提示</a>',
                     dangerouslyUseHTMLString: true,
                     duration: 10000,
diff --git a/src/decrypt/common.js b/src/decrypt/common.js
index 16d9d07..29fc926 100644
--- a/src/decrypt/common.js
+++ b/src/decrypt/common.js
@@ -2,6 +2,7 @@ const NcmDecrypt = require("./ncm");
 const QmcDecrypt = require("./qmc");
 const RawDecrypt = require("./raw");
 const MFlacDecrypt = require("./mflac");
+const MggDecrypt = require("./mgg");
 const TmDecrypt = require("./tm");
 
 
@@ -35,6 +36,9 @@ export async function CommonDecrypt(file) {
         case "mflac"://QQ Music Desktop Flac
             rt_data = await MFlacDecrypt.Decrypt(file.raw, raw_filename, raw_ext);
             break;
+        case "mgg":
+            rt_data = await MggDecrypt.Decrypt(file.raw, raw_filename, raw_ext);
+            break;
         case "tm2":// QQ Music IOS M4a
         case "tm6":// QQ Music IOS M4a
             rt_data = await TmDecrypt.Decrypt(file.raw, raw_filename);
diff --git a/src/decrypt/mgg.js b/src/decrypt/mgg.js
new file mode 100644
index 0000000..5a8ad1e
--- /dev/null
+++ b/src/decrypt/mgg.js
@@ -0,0 +1,84 @@
+const musicMetadata = require("music-metadata-browser");
+const util = require("./util");
+export {Decrypt}
+const FLAC_HEADER = [0x4F, 0x67, 0x67, 0x53, 0x00];
+
+async function Decrypt(file, raw_filename, raw_ext) {
+    // 获取扩展名
+    if (raw_ext !== "mgg") return {
+        status: false,
+        message: "File type is incorrect!",
+    };
+    // 读取文件
+    const fileBuffer = await util.GetArrayBuffer(file);
+    const audioData = new Uint8Array(fileBuffer.slice(0, -0x170));
+    const audioDataLen = audioData.length;
+    const keyData = new Uint8Array(fileBuffer.slice(-0x170));
+    const headData = new Uint8Array(fileBuffer.slice(0, 170));
+    let seed;
+    try {
+        let resp = await queryKeyInfo(keyData, headData, raw_filename);
+        let data = await resp.json();
+        seed = new Mask(data.Mask);
+
+    } catch (e) {
+        return {
+            status: false,
+            message: "此音乐无法解锁，目前mgg格式仅提供试验性支持",
+        };
+    }
+
+    for (let cur = 0; cur < audioDataLen; ++cur) {
+        audioData[cur] ^= seed.NextMask();
+    }
+    // 导出
+    const musicData = new Blob([audioData], {type: "audio/ogg"});
+
+    // 读取Meta
+    let tag = await musicMetadata.parseBlob(musicData);
+    const info = util.GetFileInfo(tag.common.artist, tag.common.title, raw_filename);
+
+    // 返回
+    return {
+        status: true,
+        title: info.title,
+        artist: info.artist,
+        ext: 'ogg',
+        album: tag.common.album,
+        picture: util.GetCoverURL(tag),
+        file: URL.createObjectURL(musicData),
+        mime: "audio/ogg"
+    }
+
+}
+
+class Mask {
+    constructor(mask) {
+        this.index = -1;
+        this.mask_index = -1;
+        this.mask128 = mask;
+    }
+
+    NextMask() {
+        this.index++;
+        this.mask_index++;
+        if (this.index === 0x8000 || (this.index > 0x8000 && (this.index + 1) % 0x8000 === 0)) {
+            this.index++;
+            this.mask_index++;
+        }
+        if (this.mask_index >= 128) {
+            this.mask_index -= 128;
+        }
+        return this.mask128[this.mask_index]
+    }
+
+}
+
+
+function queryKeyInfo(keyData, headData, filename) {
+    return fetch("https://stats.ixarea.com/collect/mgg/query", {
+        method: "POST",
+        headers: {"Content-Type": "application/json"},
+        body: JSON.stringify({Key: Array.from(keyData), Head: Array.from(headData), Filename: filename}),
+    })
+}