CORS anywhere returning proxy text, not desired target resource

问题

I am trying to set up a proxy using node, express, and an instance of cors-anywhere for my arcgis-js-api app. My server file looks like this:

import express from 'express';
import cors from 'cors';
import corsAnywhere from 'cors-anywhere';

const { PORT } = process.env;
const port = PORT || 3030;

var app = express();

let proxy = corsAnywhere.createServer({
    originWhitelist: [], // Allow all origins
    requireHeaders: [], // Do not require any headers.
    removeHeaders: [], // Do not remove any headers.
});

app.use(cors());

app.get('/proxy/:proxyUrl*', (req, res) => {
    req.url = req.url.replace('/proxy/', '/');
    proxy.emit('request', req, res);
});

app.get('*', (req, res) => {
    res.sendFile(path.resolve(__dirname, 'index.html'));
});

app.listen(port, () => {
    console.log(`App listening on port ${port}`);
});

When I go to http://localhost:3030/proxy/https://maps.disasters.nasa.gov/ags04/rest/services/ca_fires_202008/sentinel2/MapServer?f=json, I get to my target json no problem, with access-control-allow-origin: * correctly tacked on.

In my front end html (an arcgis-js-api app), I am calling that same url:

var layer = new MapImageLayer({
  url: 'http://localhost:3030/proxy/https://maps.disasters.nasa.gov/ags04/rest/services/ca_fires_202008/sentinel2/MapServer?f=json',
});

My network tab shows a response not of the expected JSON, but of the text of the cors-anywhere proxy:

For those familiar with the arcgis-js-api, you can also preconfigure use of a proxy:

urlUtils.addProxyRule({
  urlPrefix: 'maps.disasters.nasa.gov',
  proxyUrl: 'http://localhost:3030/proxy/',
});

If I do it this way, the network tab shows that the call to the localhost:3030/proxy/<url> is returning the index.html page, not the desired json.

Why is the proxy giving the expected/required result when I access the url directly through the browser, but not when being called from my front end file? Thanks for reading.

回答1:

I checked the browser console and noticed that the url being sent to the proxy instead of this

http://localhost:3030/proxy/https://maps.disasters.nasa.gov/ags04/rest/services/ca_fires_202008/sentinel2/MapServer?f=json

looks like this

http://localhost:3030/proxy/https:/maps.disasters.nasa.gov/ags04/rest/services/ca_fires_202008/sentinel2/MapServer?f=json

Not sure why it's happening, but as a quick fix you can replace

req.url = req.url.replace('/proxy/', '/');

with

req.url = req.url.replace('/proxy/https:/', '/https://');

来源：https://stackoverflow.com/questions/65176887/cors-anywhere-returning-proxy-text-not-desired-target-resource

标签

node.js

express

proxy

cors

arcgis-js-api