Twitter: verifying username and password in C#

Question

Bounty Question

I am using c# 3.5 Window Forms Application. I am using the code mentioned in the accepted answer. and I am getting below error

The remote server returned an error: (401) Unauthorized.

Sample code to verify the UserName and Password will be really appreciated

Bounty Question Ends

---

I have an application with the following use-case: when the user first starts using the application, he inputs his username and password. Then, at a much later stage, the application may update his status.

Currently I'm using Twitterizer, but I believe the question is beyond the scope of the specific library I'm using. Following are the two relevant lines of code:

Twitter twitter = new Twitter("username", "password", "source"); 
twitter.Status.Update("update");

The construction of the Twitter object does not throw an exception if the username/password are incorrect. This is probably because nothing is sent at this point. On the other hand, the status update does throw an exception if the username/password are invalid.

My problem is that I want to validate the username/password at the point of user input, not when trying to post the update.

How can I validate the username/password without posting anything (in Twitterizer or otherwise)?

Answer 1

Taking a quick look at the verify_credentials API as mentioned by peSHIr, I wrote a little routine which seems to do the trick. It's late, but I was able to test it a couple of times and seems to work.

In my function, I am just returning true if I I get an HttpResponseCode.OK, and false if I get anything else or an exception is thrown. If twitter does not like the uid/password an exception will be thrown with a 401 error (not authorized.)

public bool CheckTwitterCredentials(string UserName, string Password)
{
    // Assume failure
    bool Result = false;

    // A try except block to handle any exceptions
    try {
        // Encode the user name with password
        string UserPass = Convert.ToBase64String(
            System.Text.Encoding.UTF8.GetBytes(UserName + ":" + Password));

        // Create our HTTP web request object
        HttpWebRequest Request = 
            (HttpWebRequest)WebRequest.Create("http://twitter.com/account/verify_credentials.xml");

        // Set up our request flags and submit type
        Request.Method = "GET";
        Request.ContentType = "application/x-www-form-urlencoded";

        // Add the authorization header with the encoded user name and password
        Request.Headers.Add("Authorization", "Basic " + UserPass);

        // Use an HttpWebResponse object to handle the response from Twitter
        HttpWebResponse WebResponse = (HttpWebResponse)Request.GetResponse();

        // Success if we get an OK response
        Result = WebResponse.StatusCode == HttpStatusCode.OK;
    } catch (Exception Ex) {
        System.Diagnostics.Debug.WriteLine("Error: " + Ex.Message);
    }

    // Return success/failure
    return Result;
}