Oauth2 Yahoo Gemini API

Question

I am having trouble calling Yahoo Gemini API to access Yahoo Gemini Advertising from my C# console (desktop) application.

Here are steps I used:

1. Create an installed application on https://developer.yahoo.com/apps/create/. This gave me both {Client ID} and {Client Secret}.
2. https://api.login.yahoo.com/oauth2/request_auth?client_id={Client ID} &redirect_uri=oob&response_type=code&language=en-us. This will take me to the yahoo login screen where I sign in. Press the Agree button and the next screen shows the seven-letter authorization code (say nzbcns9). I write down this authorization code.

3. Then I use the following code to try to get the access token:

   class Program
   {
   static void Main(string[] args)
   {
       string clientId = {Client ID};
       string secret = {Client Secret};
   
       var request = WebRequest.Create(@"https://api.login.yahoo.com/oauth2/get_token");
       request.Method = "POST";
   
       SetBasicAuthHeader(request, clientId, secret);
   
       string postData = "grant_type=authorization_code&redirect_uri=oob&code=nzbcns9";
       ASCIIEncoding encoding = new ASCIIEncoding();
       byte[] byte1 = encoding.GetBytes(postData);
       request.ContentLength = byte1.Length;
       Stream dataStream = request.GetRequestStream();
       dataStream.Write(byte1, 0, byte1.Length);
       dataStream.Close();
   
       request.ContentType = "application/x-www-form-urlencoded";
       var response = request.GetResponse();
       Console.WriteLine(((HttpWebResponse)response).StatusDescription);
   }
   
   static void SetBasicAuthHeader(WebRequest request, String userName, String userPassword)
   {
       string authInfo = userName + ":" + userPassword;
       authInfo = Convert.ToBase64String(Encoding.Default.GetBytes(authInfo));
       request.Headers["Authorization"] = "Basic " + authInfo;
   }
   }
   

Then I get

Unhandled Exception: System.Net.WebException: The remote server returned an error: (401) Unauthorized. at System.Net.HttpWebRequest.GetResponse().

What did I do wrong?

I also try to post the same message using Fiddler, I get

{"error":"invalid_request"}

Answer 1

I tried your code and what worked for me was to put the line request.ContentType = "application/x-www-form-urlencoded"; BEFORE Stream dataStream = request.GetRequestStream();

So this worked:

    string postData = "grant_type=authorization_code&redirect_uri=oob&code=nzbcns9";
    ASCIIEncoding encoding = new ASCIIEncoding();
    byte[] byte1 = encoding.GetBytes(postData);
    request.ContentLength = byte1.Length;
    request.ContentType = "application/x-www-form-urlencoded";
    Stream dataStream = request.GetRequestStream();
    dataStream.Write(byte1, 0, byte1.Length);
    dataStream.Close();

Answer 2

Neither of these worked for me, but it did work once I changed the SetBasicAuthHeader to use ISO-8859-1 encoding:

    static void SetBasicAuthHeader( WebRequest request, String userName, String userPassword )
    {
        string authInfo = userName + ":" + userPassword;
        authInfo = Convert.ToBase64String( Encoding.GetEncoding( "ISO-8859-1" ).GetBytes( authInfo ) );
        request.Headers[ "Authorization" ] = "Basic " + authInfo;
    }