Node.js connection reset on file upload with multer

问题

I have a node/express app that handles file uploads with multer. Everything works well on my local machine, but on the server, if the uploaded file exceeds a couple of Mbs, the browser stops with a "connection reset" error.

Here is a simple test version of the upload script:

var express = require('express');
var multer = require('multer');

// Create server
var app = express();

// Start server
function startServer() {
    var port = 8888;
    server = app.listen(port, function () {
        console.log('Node version:' + process.versions.node);
        console.log('Express server listening on port %d in %s mode', port, app.settings.env);
    });
}

var upload = multer({dest: './tmp/'});

var app = express()

app.post('/', upload.single('data'), function (req, res, next) {
    console.log(req.file);
});

startServer();

And here's the html page to test the upload:

<!doctype html>
<html>
    <head>
        <meta charset="utf-8">
        <meta http-equiv="x-ua-compatible" content="ie=edge">
        <title>Test Upload</title>
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">

    </head>
    <body>
        <p>Hello world! This is a test upload.</p>

        <form method="post" action="http://192.168.1.234:8888" enctype="multipart/form-data">
            <label>file</label><br>
            <input type="file" name="data"><br>

            <input type="submit" name="submit" value="Upload">
        </form>


    </body>
</html>

I tested on two different servers – a VPS and a bare-metal box – I ended up with the same error on both servers. The upload starts and I can see a chunck of the file in my ./tmp directory, but it never finishes and doesn't throw any error, neither in node nor in the syslog.

回答1:

@NadavL was right, despite the fact that I had no front server, node was timing out itself.

It's written in the docs that there's no timeout in node by default. Express might override that but I couldn't find any information on the matter.

To define a specific timeout globally, you can proceed by changing the socket timeout when the server connects

[…]

// Start server
function startServer() {
    var port = 8888;
    server = app.listen(port, function () {
        console.log('Node version:' + process.versions.node);
        console.log('Express server listening on port %d in %s mode', port, app.settings.env);
    });

    server.on('connection', function(socket) {
        // 10 minutes timeout
        socket.setTimeout(10 * 60 * 1000);
    });
}

But as a high timeout rises your server's exposure to Slow HTTP Attacks, you might want to change the default timeout just for a specific route – in my case, just for the upload route. In this particular case, all you have to do is change the timeout in your route's handler like so:

app.post('/myroute', function (req, res) {
    // 10 minutes timeout just for POST to myroute
    req.socket.setTimeout(10 * 60 * 1000);
    upload.single('data');
    console.log(req.file);
});

There's also a dedicated middleware to handle timeouts, it's called connect-timeout and it can be used to configure specific timeouts for different routes too (see this post on SO).

回答2:

As far as I understood my issue, receiving ERR_CONNECTION_RESET after 60 seconds uploading big files. Increasing the request timeout with req.setTimeout(value, cb) isn't enough.

The server headersTimeout field needs to be increased manually as such: