NodeJS proxy not working as intended - angularjs

Question

The current route of the request originates on localhost:3001, goes through a proxy running on that same localhost at localhost:3001/proxy, where the request is then routed to the Salesforce instance. The proxy is made using ExpressJS and the client side app is made using AngularJS. Note: I did remember to tag my security token at the end of my password (Salesforce API requirement), although when using cURL, this doesn't seem to be necessary. Here are a series of HTTP traces that will hopefully provide some clues:
HTTP Request Log from Angular.JS App:
POST /proxy HTTP/1.1
Host: localhost:3001
Connection: keep-alive
Content-Length: 234
Pragma: no-cache
Cache-Control: no-cache
X-User-Agent: salesforce-toolkit-rest-javascript/v29.0
Origin: http://localhost:3001
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.107 Safari/537.36
Content-Type: application/x-www-form-urlencoded
Accept: application/json, text/plain, */*
SalesforceProxy-Endpoint: https://uniquename.salesforce.com/services/oauth2/token
Referer: http://localhost:3001/
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.8
Cookie: liveagent_oref=; liveagent_ptid=3c69c2f9-139d-4439-ba6c-fd8d9dcae101; liveagent_vc=5
grant_type=password&client_id=3MVGxyzxyzxyzxyz&client_secret=99889988&username=first.last%40email.com&password=pswdwACYodaYfHs
400 Bad Request
Object {error_description: "grant type not supported", error: "unsupported_grant_type"}
Relevant Express.JS code used for proxy routing:
app.all('/proxy', function(req, res) {
var url = req.header('SalesforceProxy-Endpoint');
console.log(req.body); //prints all form data variables in JSON format
console.log(res.body); //undefined
request({url: url}).pipe(res).on('error', function(error){
//I think I may need to pipe more information using request?
console.log(error);
});
});
Request details using cURL:
curl -v https://uniquename.salesforce.com/services/oauth2/token
-d "grant_type=password" -d "client_id=3MVGxyzxyzxyzxyz"
-d "client_secret=99889988" -d "username=jfirst.last#email.com" -d "password=pswd"
> POST /services/oauth2/token HTTP/1.1
> User-Agent: curl/7.41.0
> Host: uniquename.salesforce.com
> Accept: */*
> Content-Length: 207
> Content-Type: application/x-www-form-urlencoded
>
* upload completely sent off: 207 out of 207 bytes
< HTTP/1.1 200 OK
< Date: Wed, 29 Jul 2015 06:04:55 GMT
< Set-Cookie: BrowserId=auu1mgvHSMS1EedDEduz8Q;Path=/;Domain=.salesforce.com;Exp
ires=Sun, 27-Sep-2015 06:04:55 GMT
< Expires: Thu, 01 Jan 1970 00:00:00 GMT
< Pragma: no-cache
< Cache-Control: no-cache, no-store
< Content-Type: application/json;charset=UTF-8
< Transfer-Encoding: chunked
<
{
"id":"https://test.salesforce.com/id/05390530530",
"issued_at":"1438132525896197",
"token_type":"Bearer",
"instance_url":"https://uniquename.salesforce.com",
"signature":"blahblah",
"access_token":"XXXXXXXXXXXXXXXXX"
}
* Connection #0 to
host uniquename.salesforce.com left intact
As you can see, I get back a valid response from the cURL request. I suspect something is wrong with the proxy, as it may not be forwarding all the form data to Salesforce, but I'm not sure how to debug that in Express.JS. The reason I suspect this is because if I try curl https://uniquename.salesforce.com/services/oauth2/token it returns the same unsupported_grant_type error.

Answer 1

I finally got this working by switching to use the cors-anywhere proxy. I deploy my AngularJS app on port 8080, and the proxy on port 3001. My packages are managed using npm and grunt. Here is the code for the proxy:
var host = 'localhost';
var port = 3001;
var cors_proxy = require('cors-anywhere');
cors_proxy.createServer().listen(port, host, function() {
console.log('CORS proxy running on ' + host + ':' + port);
});
And here is how I'm making the HTTP request in AngularJS (you have to fill in your own credentials in the data object):
var login = {
method: 'POST',
url: 'http://localhost:3001/https://login.salesforce.com/services/oauth2/token',
data: 'grant_type=password&client_id='+encodeURIComponent(CLIENT_ID)+'&client_secret='+encodeURIComponent(CLIENT_SECRET)+'&username='+encodeURIComponent(EMAIL)+'&password='+encodeURIComponent(PASSWORD+USER_SECURITY_TOKEN),
headers: {
'Content-Type': 'application/x-www-form-urlencoded',
'Accept': '*/*'
}
};
$http(login).success(function(response){
console.log(response);
})
.error( function(response, status){
console.log(response);
console.log("Status: " + status);
});
You can run the proxy with the node server.js command, and run the AngularJS app with grunt. I hope this helps someone out, this was a tough problem to solve.

Answer 2

I don't think you're proxying everything in the HTTP request. I've included some code below that will pass the request method and the request headers to your endpoint.. Also try using the 'request-debug' library so you can compare the proxy HTTP request vs your curl request and look for differences
var express = require('express');
var app = express();
var request = require('request');
require('request-debug')(request);
app.all('/proxy', function(req, res) {
var url = req.header('SalesforceProxy-Endpoint');
var options = {
url: url,
method: req.method,
headers: req.headers
}
request(options).pipe(res).on('error', function (error, response, body) {
if (!error && response.statusCode == 200) {
//TODO: do something useful with the response
} else {
console.log('ERROR: ' + error);
}
});
});