CODEWITHSUNDEEP
.netc#-4.0facebook-graph-apisystem.netsystem.net.webexception
Umair Khan Jadoon
Umair Khan Jadoon

Reputation: 2914

Getting '(400) Bad Request' with GetResponseStream() in C#

I am using the following code to send a get request to facebook graph api oauth server. 

public string GetAccessToken(string code)
    {
        HttpWebRequest req = (HttpWebRequest) WebRequest.Create(@"https://graph.facebook.com/oauth/access_token?client_id=249725835046216&redirect_uri=http://localhost:2794/&client_secret=APP_SECRETa&code=" + code);
        HttpWebResponse res = (HttpWebResponse)req.GetResponse();
        string response=res.GetResponseStream().ToString();
        return response;
    }

The above code throws the following exception:

The remote server returned an error: (400) Bad Request.

Meanwhile if I type the same url in browser, it works. Please help, where am I wrong?

(P.S In the URL, I am surely replacing APP_SECRET with the secret key)

Upvotes: 1

Views: 4713

Answers (5)

toha
toha

Reputation: 5510

This is what happened to me and how to solve that:

  1. Redirect the user to

    https://www.facebook.com/dialog/oauth?client_id=YOUR_APP_ID&redirect_uri=YOUR_URL

  2. After user click allow, it'll hit our Redirect Uri

  3. At that point we'll get the code and we need to do a server side HTTP Get to the following Url to exchange the code with our oAuth access token:

    https://graph.facebook.com/oauth/access_token?client_id=YOUR_APP_ID&redirect_uri=YOUR_URL&client_secret=YOUR_APP_SECRET&code=THE_CODE_FROM_ABOVE

Now at step 3, I kept on getting Http 400 response back.

So after some research, I found out that on that redirect_uri that we submitted on step 3 doesn't do anything but validate the request. Thus, the value need to match with step 2.

In short :

redirect_uri MUST MATCH both step 2 and step 3

Upvotes: 0

Chris Beemster
Chris Beemster

Reputation: 362

The redirect URL needs to be the same as the one that you posten when getting a code.

Please check this article, helped me!
http://www.ronaldwidha.net/2011/03/24/facebook-oauth-access_token-return-http-400-error-validating-verification-code/

Upvotes: 0

Hans
Hans

Reputation: 13040

You have to encode the parameters of your URL. You could use the HttpUtility class for encoding your parameters.

Upvotes: 1

RoccoC5
RoccoC5

Reputation: 4213

Your querystring parameters should be UrlEncoded:

HttpWebRequest req = (HttpWebRequest) WebRequest.Create(@"https://graph.facebook.com/oauth/access_token?client_id=249725835046216&redirect_uri=" + UrlEncode("http://localhost:2794/") + "&client_secret=" + UrlEncode(APP_SECRET) + "&code=" + UrlEncode(code));

Upvotes: 2

pabdulin
pabdulin

Reputation: 35225

Most probably you need to specify user agent to satisfy some check logic of a server:

HttpWebRequest req = (HttpWebRequest) WebRequest.Create(@"https://...&code=" + code);
req.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";

try this and see if it helps.

Upvotes: 0

Related Questions