Pipe a uploaded file to a remote server with node

2019-02-13 05:03发布

站内问答 / 后端开发
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I want to upload a file in my app.js server , which should pipe that file to a crossdomain server like my upload.js server.

The full code can be found under the following link

The upload.js server is working. My problem is the app.js server. Request seems to be capable of streaming files (https://github.com/request/request#streaming). But I dont get it working. I am always getting : [Error: Invalid protocol] in my app.js.

It musst be this line:

fs.createReadStream(file.path).pipe(request.post('localhost:4000/upload'))

I changed post to put and in my upload.js the post method also to put, but it results in the same error.

My Goal is to upload a file from the html page to localhost:3000/upload which pipes the file to localhost:4000/upload (ideally with same filename) . But I dont get it working (this post doesn't helped me).

app.js:

var express = require('express')
    , multiparty = require('multiparty')
    , request = require('request')
    , fs = require('fs')
    , util = require('util')
    , http = require('http');

var app = express();
app.use('/static', express.static('static'));

process.on('uncaughtException', function (err) {
    console.log(err);
});

app.get('/', function (req, res) {
    res.redirect('static/index.html');
});

app.post('/upload', function(req, res, next){

    //https://github.com/request/request#streaming

    var form = new multiparty.Form();

    form.parse(req, function(err, fields, files) {
        res.writeHead(200, {'content-type': 'text/plain'});
        res.write('received upload:\n\n');
        res.end(util.inspect({fields: fields, files: files}));
    });
    form.on('file', function(name,file) {

        //stream it to localhost:4000 with same name
        fs.createReadStream(file.path).pipe(request.post('localhost:4000/upload'))

        console.log(file.path);
    });

});

var server = app.listen(3000, '0.0.0.0' ,function () {
    var host = server.address().address;
    var port = server.address().port;

    console.log('Example app listening at http://%s:%s', host, port);
});

index.html:

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>Upload</title>
</head>
<body>
  <h2>Upload</h2>
  <form method="post" action="/upload" enctype="multipart/form-data">
    <input type="file" id="file" name="file" />
    <button>upload</button>
  </form>
</body>
</html>

upload.js:

var express = require('express')
    , multiparty = require('multiparty')
    , cors = require('cors')
    , util = require('util')
    , app = express();

app.use(cors());
process.on('uncaughtException', function (err) {
    console.log(err);
});

app.get('/', cors(), function(req, res, next){
    res.json({msg: 'This is CORS-enabled for all origins!'});
});

app.post('/upload', cors(), function(req, res, next){
    var form = new multiparty.Form();

    form.parse(req, function(err, fields, files) {
        res.writeHead(200, {'content-type': 'text/plain'});
        res.write('received upload:\n\n');
        res.end(util.inspect({fields: fields, files: files}));
    });
    form.on('file', function(name,file) {
        console.log(file);
        console.log(name);
    });

});

app.listen(4000, function(){
    console.log('CORS-enabled web server listening on port 4000');
});

3条回答
姐就是有狂的资本
2楼-- · 2019-02-13 05:15

You actually can do stream.pipe(request.post(url));, and then on the another server your req variable will have a stream-like behavior, so you should be able to req.pipe(fs.createWriteStream(path));.

Use req.params on your route to preserve the filename.

Example code for server one (use some hashing like md5 to validate your request):

const stream = fs.createReadStream(path);

const md5 = crypto.createHash('md5')
    .update(`${filename}${secret}`)
    .digest('hex').toUpperCase();

const url = `http://${host}/upload/${md5}/${filename}`;

const r = request.post(url, (err, resp, body) => {});

stream.pipe(r);

Example code for server two:

router.post('/upload/:md5/:filename', function(req, res, next) {
    const { md5, filename } = req.params;

    const check = crypto.createHash('md5')
        .update(`${filename}${secret}`)
        .digest('hex').toUpperCase();

    if (md5 !== check) {
        res.writeHead(403);
        res.end('403');
        return;
    }

    req.pipe(fs.createWriteStream(filename));

    req.on('end', next);
});
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We Are One
3楼-- · 2019-02-13 05:21

I had a similar problem but I wanted to stream the file directly to the remote server instead of saving it locally first. Here's my modifications to get streaming to work:

app.post('/upload', function(request, response, next) {
    var form = new multiparty.Form();

    form.on('part', function(formPart) {
        var contentType = formPart.headers['content-type'];

        var formData = {
            file: {
                value: formPart,
                options: {
                    filename: formPart.filename,
                    contentType: contentType,
                    knownLength: formPart.byteCount
                }
            }
        };

        requestJs.post({
            url: 'http://localhost:4000/upload',
            formData: formData,

            // These may or may not be necessary for your server:
            preambleCRLF: true,
            postambleCRLF: true
        });
    });

    form.on('error', function(error) {
        next(error);
    });

    form.on('close', function() {
       response.send('received upload');
    });

    form.parse(request);
});
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乱世女痞
4楼-- · 2019-02-13 05:26

Updated

I believe you're missing the protocol from the url. It should work, if you add the http protocol to the url:

fs.createReadStream(file.path).pipe(request.post('http://localhost:4000/upload'))

Make Upload work

When you pipe the file contents to the POST function in upload.js, the multipart form data is lost. You need to create a new POST request and pass the original file contents.

Do the following in app.js:

 form.on('file', function(name, file) {

    var formData = {
      file: {
        value:  fs.createReadStream(file.path),
        options: {
          filename: file.originalFilename
        }
      }
    };

    // Post the file to the upload server
    request.post({url: 'http://localhost:4000/upload', formData: formData});
}

This will also pass the original filename. For more information see: https://github.com/request/request#multipartform-data-multipart-form-uploads

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