/// <summary>
/// Calls Twitter with a request token and a verifier, and receives an access token and an access token secret
/// </summary>
/// <param name="userRequestToken">request token obtained from Twitter in the first place (see above) </param>
/// <param name="userVerifier">corresponds to <c>oauth_verifier</c> in Step 2 of Token sign in</param>
/// <param name="twtrConsumerKey">ConsumerKey issued by Twitter to the calling app.</param>
/// <param name="twtrConsumerSecret">ConsumerSecret issued by Twitter to the calling app.</param>
/// <returns>a tuple where the first item is the access token and the second the access token secret</returns>
private async Task <Tuple <string, string> > GetTwitterAccessTokenAndTokenSecret(string userRequestToken, string userVerifier, string twtrConsumerKey, string twtrConsumerSecret)
{
// access token
string accessToken = null;
// access token secret
string accessTokenSecret = null;
// Response string returned by third party id provider
string responseString = null;
// Construct the request token request to Twitter
TwitterAuthHeader twitterAccessTokenRequest = new TwitterAuthHeader
{
SigningKey = twtrConsumerSecret + "&" + Uri.EscapeDataString(userRequestToken),
OauthToken = userRequestToken,
OauthVerifier = userVerifier,
OauthCallback = twtrAccessTokenURL,
OauthConsumerKey = Uri.EscapeDataString(twtrConsumerKey), // must escape the consumer key
OauthNonce = OAuthUtil.GeneratePseudoRandomAlphaNumericString(32),
OauthSignatureMethod = "HMAC-SHA1",
OauthTimestamp = OAuthUtil.SecondsSinceBeginningOfTime,
OauthVersion = "1.0"
};
// Create the outgoing HTTP request
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(twtrAccessTokenURL);
request.Method = "POST";
request.Headers["Authorization"] = twitterAccessTokenRequest.AuthHeader(twtrAccessTokenURL, "POST");
try
{
// Parse the incoming response
WebResponse response = await request.GetResponseAsync();
using (Stream responseStream = response.GetResponseStream())
using (StreamReader r = new StreamReader(responseStream))
{
responseString = r.ReadToEnd();
var responseValues = System.Web.HttpUtility.ParseQueryString(responseString);
// Check whether the response is empty
if (responseValues == null)
{
throw new OAuthException(OAuthErrors.ServiceUnavailable_503_Twitter_3);
}
accessToken = responseValues["oauth_token"];
accessTokenSecret = responseValues["oauth_token_secret"];
}
}
catch (Exception ex)
{
throw new OAuthException(OAuthErrors.ServiceUnavailable_503_Twitter_3, ex);
}
return(new Tuple <string, string>(accessToken, accessTokenSecret));
}
/// <summary>
/// Calls Twitter with the access token and access token secret and expects the user profile (aka decodes the token)
/// </summary>
/// <param name="accessToken">Twitter user access token</param>
/// <param name="accessTokenSecret">Twitter user access token secret</param>
/// <param name="twtrConsumerKey">ConsumerKey issued by Twitter to the calling app.</param>
/// <param name="twtrConsumerSecret">ConsumerSecret issued by Twitter to the calling app.</param>
/// <returns>a user profile specific to Twitter</returns>
private async Task <TwitterProfile> TwitterImplicitFlow(string accessToken, string accessTokenSecret, string twtrConsumerKey, string twtrConsumerSecret)
{
// Construct the request token request to Twitter
TwitterAuthHeader twitterUserProfileRequest = new TwitterAuthHeader
{
SigningKey = twtrConsumerSecret + "&" + accessTokenSecret,
OauthToken = accessToken,
OauthConsumerKey = Uri.EscapeDataString(twtrConsumerKey), // must escape the consumer key
OauthNonce = OAuthUtil.GeneratePseudoRandomAlphaNumericString(32),
OauthSignatureMethod = "HMAC-SHA1",
OauthTimestamp = OAuthUtil.SecondsSinceBeginningOfTime,
OauthVersion = "1.0"
};
// User profile extracted from the token
TwitterProfile tokenProfile = null;
// Response string returned by third party id provider
string responseString = null;
// Create the outgoing HTTP request
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(twtrGetProfileURL);
request.Method = "GET";
request.Headers["Authorization"] = twitterUserProfileRequest.AuthHeader(twtrGetProfileURL, "GET");
try
{
// Parse the incoming response
WebResponse response = await request.GetResponseAsync();
using (Stream responseStream = response.GetResponseStream())
using (StreamReader r = new StreamReader(responseStream))
{
responseString = r.ReadToEnd();
}
if (string.IsNullOrEmpty(responseString))
{
throw new OAuthException(OAuthErrors.ServiceUnavailable_503_Twitter_2);
}
tokenProfile = JsonConvert.DeserializeObject <TwitterProfile>(responseString);
}
catch (Exception ex)
{
throw new OAuthException(OAuthErrors.ServiceUnavailable_503_Twitter_2, ex);
}
return(tokenProfile);
}
/// <summary>
/// Constructs the signed request syntax according to Twitter's spec.
/// </summary>
/// <param name="url">url for request to Twitter</param>
/// <param name="method">string representing the HTTP method (GET versus POST)</param>
/// <returns>the properly formatted HTTP request string.</returns>
private string SignedHTTPRequest(string url, string method)
{
string requestString = string.Empty;
foreach (PropertyInfo prop in this.GetType().GetProperties())
{
object[] attributes = prop.GetCustomAttributes(typeof(TwitterAuthHeaderAttribute), true);
if (attributes.Length > 0)
{
string propVal = (string)prop.GetValue(this);
if (!string.IsNullOrEmpty(propVal))
{
string propName = ((TwitterAuthHeaderAttribute)attributes[0]).Name;
requestString += '&' + propName + "=" + propVal;
}
}
}
// The two '&' chars after POST and the TokenURL must stay unescaped, but the rest must be escaped.
requestString = method + "&" + Uri.EscapeDataString(url) + "&" + Uri.EscapeDataString(requestString.Substring(1));
return(OAuthUtil.Base64HMACString(requestString, this.SigningKey));
}