server.js

'use strict';

const express = require('express');
const cors = require('cors');
const fs = require('fs');
const path = require('path');
const app = express();
const port = process.env.PORT || 8080;

// Replace with your actual logging mechanism
const log = {
    warn: console.warn,
    error: console.error,
    debug: console.log,
};

// Directory where recordings will be stored
const recordingDirectory = path.join(__dirname, 'rec');

// Flag to enable/disable server recording
const isServerRecordingEnabled = true;

// CORS options
const corsOptions = {
    origin: '*',
    methods: ['POST'],
};

// Middleware
app.use(express.json());
app.use(cors(corsOptions));

// Ensure the recording directory exists
function ensureRecordingDirectoryExists() {
    if (!fs.existsSync(recordingDirectory)) {
        fs.mkdirSync(recordingDirectory, { recursive: true });
    }
}

// Endpoint to handle recording uploads
app.post('/recSync', (req, res) => {
    try {
        if (!isServerRecordingEnabled) {
            return res.status(403).send('Server recording is disabled');
        }

        const { fileName } = req.query;

        if (!fileName) {
            return res.status(400).send('Filename not provided');
        }

        if (!isValidRecFileNameFormat(fileName)) {
            log.warn('[RecSync] - Invalid file name', fileName);
            return res.status(400).send('Invalid file name');
        }

        ensureRecordingDirectoryExists();

        const filePath = path.join(recordingDirectory, fileName);
        const writeStream = fs.createWriteStream(filePath, { flags: 'a' });

        req.pipe(writeStream);

        writeStream.on('error', (err) => {
            log.error('[RecSync] - Error writing to file:', err.message);
            res.status(500).send('Internal Server Error');
        });

        writeStream.on('finish', () => {
            log.debug('[RecSync] - File saved successfully:', fileName);
            res.status(200).send('File uploaded successfully');
        });

        req.on('error', (err) => {
            log.error('[RecSync] - Error processing request:', err.message);
            res.status(500).send('Internal Server Error');
        });
    } catch (err) {
        log.error('[RecSync] - Error processing upload', err.message);
        res.status(500).send('Internal Server Error');
    }
});

// Start the server
app.listen(port, () => {
    log.debug(`Server is running on http://localhost:${port}`);
});

// Utils
function isValidRecFileNameFormat(input) {
    if (typeof input !== 'string') {
        return false;
    }
    if (!input.startsWith('Rec_') || !input.endsWith('.webm')) {
        return false;
    }
    return !hasPathTraversal(input);
}

function hasPathTraversal(input) {
    const pathTraversalPattern = /(\.\.(\/|\\))+/;
    return pathTraversalPattern.test(input);
}