From fce4734ed9a5aea2beead12c965ea4746fb2b175 Mon Sep 17 00:00:00 2001
From: MengYX <admin@mengyx.cn>
Date: Fri, 17 Dec 2021 06:24:21 +0800
Subject: [PATCH] feat(QMCv2): use js decoder

(cherry picked from commit c24e5d29733cfa771dd41ae40032029c6bbb9186)
---
 src/decrypt/qmc.ts                    | 21 +++++++++------------
 src/decrypt/{qmcv2.ts => qmc_wasm.ts} |  2 +-
 2 files changed, 10 insertions(+), 13 deletions(-)
 rename src/decrypt/{qmcv2.ts => qmc_wasm.ts} (97%)

diff --git a/src/decrypt/qmc.ts b/src/decrypt/qmc.ts
index 91a652e..0ff1350 100644
--- a/src/decrypt/qmc.ts
+++ b/src/decrypt/qmc.ts
@@ -10,7 +10,7 @@ import {
   WriteMetaToMp3
 } from "@/decrypt/utils";
 import {parseBlob as metaParseBlob} from "music-metadata-browser";
-import {DecryptQMCv2} from "./qmcv2";
+import {DecryptQMCWasm} from "./qmc_wasm";
 
 
 import iconv from "iconv-lite";
@@ -55,22 +55,19 @@ export async function Decrypt(file: Blob, raw_filename: string, raw_ext: string)
   const fileBuffer = await GetArrayBuffer(file);
   let musicDecoded: Uint8Array | undefined;
 
-  if (version === 2) {
-    const v2Decrypted = await DecryptQMCv2(fileBuffer);
+  if (version === 2 && globalThis.WebAssembly) {
+    console.log("qmc: using wasm decoder")
+    const v2Decrypted = await DecryptQMCWasm(fileBuffer);
     // 如果 v2 检测失败，降级到 v1 再尝试一次
     if (v2Decrypted) {
       musicDecoded = v2Decrypted;
-    } else {
-      version = 1;
     }
   }
-
-  if (version === 1) {
-    const seed = new QmcStaticCipher();
-    musicDecoded = new Uint8Array(fileBuffer)
-    seed.decrypt(musicDecoded, 0);
-  } else if (!musicDecoded) {
-    throw new Error(`解密失败: ${raw_ext}`);
+  if (!musicDecoded) {
+    // may throw error
+    console.log("qmc: using js decoder")
+    const d = new QmcDecoder(new Uint8Array(fileBuffer))
+    musicDecoded = d.decrypt()
   }
 
   const ext = SniffAudioExt(musicDecoded, handler.ext);
diff --git a/src/decrypt/qmcv2.ts b/src/decrypt/qmc_wasm.ts
similarity index 97%
rename from src/decrypt/qmcv2.ts
rename to src/decrypt/qmc_wasm.ts
index 3189426..7a1fd49 100644
--- a/src/decrypt/qmcv2.ts
+++ b/src/decrypt/qmc_wasm.ts
@@ -29,7 +29,7 @@ function MergeUint8Array(array: Uint8Array[]): Uint8Array {
  * @param  {ArrayBuffer} mggBlob 读入的文件 Blob
  * @return {Promise<Uint8Array|false>}
  */
-export async function DecryptQMCv2(mggBlob: ArrayBuffer) {
+export async function DecryptQMCWasm(mggBlob: ArrayBuffer) {
   // 初始化模组
   const QMCCrypto = await QMCCryptoModule();