forked from um/web
100 lines
2.9 KiB
JavaScript
100 lines
2.9 KiB
JavaScript
const musicMetadata = require("music-metadata-browser");
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const util = require("./util");
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export {Decrypt}
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async function Decrypt(file, raw_filename, raw_ext) {
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// 获取扩展名
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if (raw_ext !== "mflac") return {
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status: false,
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message: "File type is incorrect!",
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};
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// 读取文件
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const fileBuffer = await util.GetArrayBuffer(file);
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const audioData = new Uint8Array(fileBuffer.slice(0, -0x170));
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const audioDataLen = audioData.length;
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// 转换数据
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const seed = new Mask();
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if (!seed.DetectMask(audioData)) return {
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status: false,
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message: "此音乐无法解锁，目前mflac格式不提供完整支持",
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};
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for (let cur = 0; cur < audioDataLen; ++cur) {
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audioData[cur] ^= seed.NextMask();
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}
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// 导出
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const musicData = new Blob([audioData], {type: "audio/flac"});
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const musicUrl = URL.createObjectURL(musicData);
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// 读取Meta
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let tag = await musicMetadata.parseBlob(musicData);
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const info = util.GetFileInfo(tag.common.artist, tag.common.title, raw_filename, "flac");
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let picUrl = util.GetCoverURL(tag);
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// 返回
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return {
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status: true,
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filename: info.filename,
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title: info.title,
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artist: info.artist,
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album: tag.common.album,
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picture: picUrl,
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file: musicUrl,
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mime: "audio/flac"
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}
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}
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class Mask {
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FLAC_HEADER = [0x66, 0x4C, 0x61, 0x43, 0x00];
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constructor() {
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this.index = -1;
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this.mask_index = -1;
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this.mask = Array(128).fill(0x00);
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}
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DetectMask(data) {
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let search_len = data.length - 256, mask;
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for (let block_idx = 0; block_idx < search_len; block_idx += 128) {
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let flag = true;
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mask = data.slice(block_idx, block_idx + 128);
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let next_mask = data.slice(block_idx + 128, block_idx + 256);
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for (let idx = 0; idx < 128; idx++) {
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if (mask[idx] !== next_mask[idx]) {
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flag = false;
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break;
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}
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}
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if (!flag) continue;
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for (let test_idx = 0; test_idx < this.FLAC_HEADER.length; test_idx++) {
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let p = data[test_idx] ^ mask[test_idx];
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if (p !== this.FLAC_HEADER[test_idx]) {
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flag = false;
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debugger;
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break;
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}
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}
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if (!flag) continue;
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this.mask = mask;
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return true;
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}
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return false;
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}
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NextMask() {
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this.index++;
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this.mask_index++;
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if (this.index === 0x8000 || (this.index > 0x8000 && (this.index + 1) % 0x8000 === 0)) {
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this.index++;
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this.mask_index++;
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}
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if (this.mask_index >= 128) {
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this.mask_index -= 128;
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}
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return this.mask[this.mask_index]
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}
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}
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