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web/src/decrypt/qmc.ts

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6.4 KiB

import {QmcMapCipher, QmcRC4Cipher, QmcStaticCipher, QmcStreamCipher} from "./qmc_cipher";
import {
AudioMimeType,
GetArrayBuffer,
GetCoverFromFile,
GetImageFromURL,
GetMetaFromFile,
SniffAudioExt,
WriteMetaToFlac,
WriteMetaToMp3
} from "@/decrypt/utils";
import {parseBlob as metaParseBlob} from "music-metadata-browser";
import {DecryptQMCWasm} from "./qmc_wasm";
import iconv from "iconv-lite";
import {DecryptResult} from "@/decrypt/entity";
import {queryAlbumCover} from "@/utils/api";
import {QmcDeriveKey} from "@/decrypt/qmc_key";
interface Handler {
ext: string
version: number
}
export const HandlerMap: { [key: string]: Handler } = {
"mgg": {ext: "ogg", version: 2},
"mgg1": {ext: "ogg", version: 2},
"mflac": {ext: "flac", version: 2},
"mflac0": {ext: "flac", version: 2},
// qmcflac / qmcogg:
// 有可能是 v2 加密但混用同一个后缀名。
"qmcflac": {ext: "flac", version: 2},
"qmcogg": {ext: "ogg", version: 2},
"qmc0": {ext: "mp3", version: 1},
"qmc2": {ext: "ogg", version: 1},
"qmc3": {ext: "mp3", version: 1},
"bkcmp3": {ext: "mp3", version: 1},
"bkcflac": {ext: "flac", version: 1},
"tkm": {ext: "m4a", version: 1},
"666c6163": {ext: "flac", version: 1},
"6d7033": {ext: "mp3", version: 1},
"6f6767": {ext: "ogg", version: 1},
"6d3461": {ext: "m4a", version: 1},
"776176": {ext: "wav", version: 1}
};
export async function Decrypt(file: Blob, raw_filename: string, raw_ext: string): Promise<DecryptResult> {
if (!(raw_ext in HandlerMap)) throw `Qmc cannot handle type: ${raw_ext}`;
const handler = HandlerMap[raw_ext];
let {version} = handler;
const fileBuffer = await GetArrayBuffer(file);
let musicDecoded: Uint8Array | undefined;
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;
}
}
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);
const mime = AudioMimeType[ext];
let musicBlob = new Blob([musicDecoded], {type: mime});
const musicMeta = await metaParseBlob(musicBlob);
for (let metaIdx in musicMeta.native) {
if (!musicMeta.native.hasOwnProperty(metaIdx)) continue
if (musicMeta.native[metaIdx].some(item => item.id === "TCON" && item.value === "(12)")) {
console.warn("try using gbk encoding to decode meta")
musicMeta.common.artist = iconv.decode(new Buffer(musicMeta.common.artist ?? ""), "gbk");
musicMeta.common.title = iconv.decode(new Buffer(musicMeta.common.title ?? ""), "gbk");
musicMeta.common.album = iconv.decode(new Buffer(musicMeta.common.album ?? ""), "gbk");
}
}
const info = GetMetaFromFile(raw_filename, musicMeta.common.title, musicMeta.common.artist)
let imgUrl = GetCoverFromFile(musicMeta);
if (!imgUrl) {
imgUrl = await getCoverImage(info.title, info.artist, musicMeta.common.album);
if (imgUrl) {
const imageInfo = await GetImageFromURL(imgUrl);
if (imageInfo) {
imgUrl = imageInfo.url
try {
const newMeta = {picture: imageInfo.buffer, title: info.title, artists: info.artist?.split(" _ ")}
if (ext === "mp3") {
musicDecoded = WriteMetaToMp3(Buffer.from(musicDecoded), newMeta, musicMeta)
musicBlob = new Blob([musicDecoded], {type: mime});
} else if (ext === 'flac') {
musicDecoded = WriteMetaToFlac(Buffer.from(musicDecoded), newMeta, musicMeta)
musicBlob = new Blob([musicDecoded], {type: mime});
} else {
console.info("writing metadata for " + ext + " is not being supported for now")
}
} catch (e) {
console.warn("Error while appending cover image to file " + e)
}
}
}
}
return {
title: info.title,
artist: info.artist,
ext: ext,
album: musicMeta.common.album,
picture: imgUrl,
file: URL.createObjectURL(musicBlob),
blob: musicBlob,
mime: mime
}
}
async function getCoverImage(title: string, artist?: string, album?: string): Promise<string> {
const song_query_url = "https://stats.ixarea.com/apis" + "/music/qq-cover"
try {
const data = await queryAlbumCover(title, artist, album)
return `${song_query_url}/${data.Type}/${data.Id}`
} catch (e) {
console.warn(e);
}
return ""
}
export class QmcDecoder {
file: Uint8Array
size: number
decoded: boolean = false
audioSize?: number
private static readonly BYTE_COMMA = ','.charCodeAt(0)
cipher?: QmcStreamCipher
constructor(file: Uint8Array) {
this.file = file
this.size = file.length
this.searchKey()
}
decrypt(): Uint8Array {
if (!this.cipher) {
throw new Error("no cipher found")
}
if (!this.audioSize || this.audioSize <= 0) {
throw new Error("invalid audio size")
}
const audioBuf = this.file.subarray(0, this.audioSize)
if (!this.decoded) {
this.cipher.decrypt(audioBuf, 0)
this.decoded = true
}
return audioBuf
}
private searchKey() {
const last4Byte = this.file.slice(-4);
const textEnc = new TextDecoder()
if (textEnc.decode(last4Byte) === 'QTag') {
const sizeBuf = this.file.slice(-8, -4)
const sizeView = new DataView(sizeBuf.buffer, sizeBuf.byteOffset)
const keySize = sizeView.getUint32(0, false)
this.audioSize = this.size - keySize - 8
const rawKey = this.file.subarray(this.audioSize, this.size - 8)
const keyEnd = rawKey.findIndex(v => v == QmcDecoder.BYTE_COMMA)
this.setCipher(rawKey.subarray(0, keyEnd))
} else {
const sizeView = new DataView(last4Byte.buffer, last4Byte.byteOffset);
const keySize = sizeView.getUint32(0, true)
if (keySize < 0x300) {
this.audioSize = this.size - keySize - 4
const rawKey = this.file.subarray(this.audioSize, this.size - 4)
this.setCipher(rawKey)
} else {
this.audioSize = this.size
this.cipher = new QmcStaticCipher()
}
}
}
private setCipher(keyRaw: Uint8Array) {
const keyDec = QmcDeriveKey(keyRaw)
if (keyDec.length > 300) {
this.cipher = new QmcRC4Cipher(keyDec)
} else {
this.cipher = new QmcMapCipher(keyDec)
}
}
}