DotNetOpenAuth 谷歌 OAuth2

在最后一个DotNetOpenAuth包中，GoogleClient扩展了OpenIdClient，有人知道我在哪里可以找到扩展DotNetOpenAuth OAuth2Client的google Oauth2的实现？

From OAuth2 和 DotNetOpenAuth - 实现 Google 自定义客户端 https://stackoverflow.com/questions/13727466/oauth2-and-dotnetopenauth-implementing-google-custom-client

public class GoogleOAuth2Client : OAuth2Client
{
    #region Constants and Fields

    /// <summary>
    /// The authorization endpoint.
    /// </summary>
    private const string AuthorizationEndpoint = "https://accounts.google.com/o/oauth2/auth";

    /// <summary>
    /// The token endpoint.
    /// </summary>
    private const string TokenEndpoint = "https://accounts.google.com/o/oauth2/token";

    /// <summary>
    /// The _app id.
    /// </summary>
    private readonly string _clientId;

    /// <summary>
    /// The _app secret.
    /// </summary>
    private readonly string _clientSecret;

    #endregion

    public const string ProviderAppendix = "__provider__=google";

    public GoogleOAuth2Client(string clientId, string clientSecret)
        : base("google")
    {
        if (string.IsNullOrWhiteSpace(clientId)) throw new ArgumentNullException("clientId");
        if (string.IsNullOrWhiteSpace(clientSecret)) throw new ArgumentNullException("clientSecret");

        this._clientId = clientId;
        this._clientSecret = clientSecret;
    }

    protected override Uri GetServiceLoginUrl(Uri returnUrl)
    {
        StringBuilder serviceUrl = new StringBuilder();

        serviceUrl.AppendFormat("{0}?scope=https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fuserinfo.email+https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fuserinfo.profile", AuthorizationEndpoint);
        serviceUrl.Append("&state=google");
        serviceUrl.AppendFormat("&redirect_uri={0}", returnUrl.ToString().ToLower());
        serviceUrl.Append("&response_type=code");
        serviceUrl.AppendFormat("&client_id={0}", _clientId);

        return new Uri(serviceUrl.ToString());
    }

    protected override IDictionary<string, string> GetUserData(string accessToken)
    {
        var client = new RestClient("https://www.googleapis.com");
        var request = new RestRequest(String.Format("/oauth2/v1/userinfo?access_token={0}", accessToken), Method.GET);
        IDictionary<String, String> extraData = new Dictionary<String, String>();

        var response = client.Execute(request);
        if (null != response.ErrorException)
        {
            return null;
        }
        else
        {
            try
            {
                var json = JObject.Parse(response.Content);

                string firstName = (string)json["given_name"];
                string lastName = (string)json["family_name"];
                string emailAddress = (string)json["email"];
                string id = (string)json["id"];

                extraData = new Dictionary<String, String>
            {
                {"accesstoken", accessToken}, 
                {"name", String.Format("{0} {1}", firstName, lastName)},
                {"firstname", firstName},
                {"lastname", lastName},
                {"email", emailAddress},
                {"id", id}                                           
            };
            }
            catch (Exception ex)
            {
                Ccl.Log.Logging.Error("Error requesting OAuth user data from Google", ex);
                return null;
            }

            return extraData;
        }
    }

    protected override string QueryAccessToken(Uri returnUrl, string authorizationCode)
    {
        StringBuilder postData = new StringBuilder();
        postData.AppendFormat("client_id={0}", this._clientId);
        postData.AppendFormat("&redirect_uri={0}", HttpUtility.UrlEncode(returnUrl.ToString().ToLower()));
        postData.AppendFormat("&client_secret={0}", this._clientSecret);
        postData.AppendFormat("&grant_type={0}", "authorization_code");
        postData.AppendFormat("&code={0}", authorizationCode);

        string response = "";
        string accessToken = "";

        var webRequest = (HttpWebRequest)WebRequest.Create(TokenEndpoint);

        webRequest.Method = "POST";
        webRequest.ContentType = "application/x-www-form-urlencoded";

        try
        {

            using (Stream s = webRequest.GetRequestStream())
            {
                using (StreamWriter sw = new StreamWriter(s))
                    sw.Write(postData.ToString());
            }

            using (WebResponse webResponse = webRequest.GetResponse())
            {
                using (var reader = new StreamReader(webResponse.GetResponseStream()))
                {
                    response = reader.ReadToEnd();
                }
            }

            var json = JObject.Parse(response);
            accessToken = (string)json["access_token"];
        }
        catch (Exception ex)
        {
            Ccl.Log.Logging.Error("Error requesting OAuth access token from Google", ex);
            return null;
        }

        return accessToken;
    }

    public override AuthenticationResult VerifyAuthentication(HttpContextBase context, Uri returnPageUrl)
    {
        string code = context.Request.QueryString["code"];
        if (string.IsNullOrEmpty(code))
        {
            return AuthenticationResult.Failed;
        }

        string accessToken = this.QueryAccessToken(returnPageUrl, code);
        if (accessToken == null)
        {
            return AuthenticationResult.Failed;
        }

        IDictionary<string, string> userData = this.GetUserData(accessToken);
        if (userData == null)
        {
            return AuthenticationResult.Failed;
        }

        string id = userData["id"];
        string name;

        // Some oAuth providers do not return value for the 'username' attribute. 
        // In that case, try the 'name' attribute. If it's still unavailable, fall back to 'id'
        if (!userData.TryGetValue("username", out name) && !userData.TryGetValue("name", out name))
        {
            name = id;
        }

        // add the access token to the user data dictionary just in case page developers want to use it
        userData["accesstoken"] = accessToken;

        return new AuthenticationResult(
            isSuccessful: true, provider: this.ProviderName, providerUserId: id, userName: name, extraData: userData);
    }
}