express.static() and sendFile() problem... creating a dynamic host with nodejs - node.js

Question

After configure my web server with nginx, i redirected all *.example.com to my nodejs server.
But before, i handle the http request, i check the url and host to see if it is correct or not.
For example, if the user writes something like what.ever.example.com
I redirect him to the main website because that host is not valid.
otherwise if the user writes something like mydomain.example.com
The user should access to this website and receive the angular APP.
So i am doing something like this.
UPDATED CODE
const express = require('express');
const cors = require('cors');
const mongoose = require('./server/database');
const bodyParser = require('body-parser');
const app = express();
var path = require('path');
// Settings
app.set('port', process.env.PORT || 4000)
// Middlewares
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(express.json());
app.use(cors());
// Routes API
app.use('/api/users', require('./server/routes/usuarios.routes'));
app.use('/api/almacenes', require('./server/routes/almacen.routes'))
app.use('/api/updates', require('./server/routes/update.routes'))
app.use('/api/dominios', require('./server/routes/dominios.routes'))
app.get('/', checkHost);
app.get('/', express.static('../nginx/app'));
app.get('/*', checkPath);
function checkHost(req, res, next) { //With this function what i pretend is check the subdomain that the user send, and if it doesn't exist. redirect it.
var domain = req.headers.host
subDomain = domain.split('.')
if (subDomain.length == 3) {
subDomain = subDomain[0].split("-").join(" ");
let query = { dominio: subDomain }
var dominiosModel = mongoose.model('dominios');
dominiosModel.findOne(query).exec((err, response) => {
if (response != null) {
if (response.dominio == subDomain) {
next();
} else {
res.writeHead(303, {
location: 'http://www.example.com/index.html'
})
res.end()
}
} else {
res.writeHead(303, {
location: 'http://www.example.com/index.html'
})
res.end()
}
})
} else {
res.writeHead(303, {
location: 'http://www.example.com/index.html'
})
res.end()
}
}
function checkPath(req, res, next) { //With this function what i want to do is.. if the user send *.example.com/whatever, i redirect it to *.example.com
if (req.url !== '/') {
res.writeHead(303, {
location: `http://${req.headers.host}`
})
res.end()
} else {
next()
}
}
// Starting Server.
app.listen(app.get('port'), () => {
console.log('Server listening on port', app.get('port'));
});
All redirects are working well, but when in checkHost the subDomain matched, it doesnt send nothing to the front... so what can i do here?

Answer 1

Try removing the response.end(). Since .sendFile() accepts a callback, it is most likely an async function, which means that calling .end() right after .sendFile() will most probably result in a blank response.

Answer 2

The sendFile function requires absolute path of the file to be sent, if root is not provided. If root is provided, a relative path could be used, but the root itself should be absolute. Check documentation here: https://expressjs.com/en/api.html#res.sendFile
You should try to send your index.html in following manner:
app.get('*', checkPath, checkHost, function (req, response) {
response.sendFile('index.html', { root: path.join(__dirname, '../nginx/app') });
}
This should work provided that the path ../nginx/app/index.html is valid, relative to the file in which this code is written.
Additionally, based on the sample code (and the comments), you probably don't need the express.static(...) at all. Unless, you need to serve 'other' files statically.
If it is needed, then the app.use(express.static('../nginx/app')) should be outside the controller. It should probably be added before the bodyParser, but since you are concerned about someone being able to access 'index.html' via the static middleware, you can consider following order for your middlewares:
//existing body parser and cors middlewares
// existing /api/* api middlewares.
app.use(checkPath);
app.use(checkHost);
app.use(express.static('../nginx/app'));
If the checkPath middleware is modified slightly to redirect to /index.html, the middleware with '*' path might not be required at all with this setup.