76 lines
2.5 KiB
JavaScript
76 lines
2.5 KiB
JavaScript
const multer = require('multer');
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const path = require('path');
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const crypto = require('crypto');
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const fs = require('fs');
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const UPLOAD_DIR = path.join(__dirname, '..', '..', 'data', 'uploads');
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if (!fs.existsSync(UPLOAD_DIR)) fs.mkdirSync(UPLOAD_DIR, { recursive: true });
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const ALLOWED_MIME = {
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'image/jpeg': ['.jpg', '.jpeg'],
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'image/png': ['.png'],
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'image/gif': ['.gif'],
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'image/webp': ['.webp'],
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'video/mp4': ['.mp4'],
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'video/webm': ['.webm'],
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};
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const ALLOWED_EXT = ['.jpg', '.jpeg', '.png', '.gif', '.webp', '.mp4', '.webm'];
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function validateMagicBytes(buffer, mime) {
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const head = buffer.slice(0, 12);
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const sigs = {
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'image/jpeg': () => head[0] === 0xFF && head[1] === 0xD8,
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'image/png': () => head[0] === 0x89 && head[1] === 0x50 && head[2] === 0x4E && head[3] === 0x47,
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'image/gif': () => head.toString('ascii', 0, 6) === 'GIF89a' || head.toString('ascii', 0, 6) === 'GIF87a',
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'image/webp': () => head.toString('ascii', 0, 4) === 'RIFF' && head.toString('ascii', 8, 12) === 'WEBP',
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'video/mp4': () => buffer.includes(Buffer.from('ftyp')),
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'video/webm': () => head[0] === 0x1A && head[1] === 0x45 && head[2] === 0xDF && head[3] === 0xA3,
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};
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if (!sigs[mime]) return false;
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try { return sigs[mime](); } catch { return false; }
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}
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const storage = multer.diskStorage({
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destination: (req, file, cb) => cb(null, UPLOAD_DIR),
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filename: (req, file, cb) => {
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const ext = path.extname(file.originalname).toLowerCase();
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cb(null, crypto.randomUUID() + ext);
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},
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});
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function fileFilter(req, file, cb) {
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const ext = path.extname(file.originalname).toLowerCase();
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if (!ALLOWED_EXT.includes(ext)) {
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return cb(new Error('不支持的文件类型，仅允许: ' + ALLOWED_EXT.join(', ')));
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}
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cb(null, true);
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}
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const upload = multer({
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storage,
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fileFilter,
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limits: {
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fileSize: 50 * 1024 * 1024,
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files: 5,
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},
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});
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function finalizeUpload(req, res, next) {
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if (!req.files || req.files.length === 0) return next();
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for (const file of req.files) {
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const buf = fs.readFileSync(file.path);
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if (!ALLOWED_MIME[file.mimetype]) {
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fs.unlinkSync(file.path);
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return res.status(400).json({ error: `不支持的文件类型: ${file.mimetype}` });
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}
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if (!validateMagicBytes(buf, file.mimetype)) {
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fs.unlinkSync(file.path);
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return res.status(400).json({ error: '文件内容与声明类型不符，可能是恶意文件' });
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}
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}
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next();
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}
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module.exports = { upload, finalizeUpload, validateMagicBytes, UPLOAD_DIR, ALLOWED_MIME };
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