// https://developers.google.com/identity/protocols/OAuth2InstalledApp
public static OAuthRequest BuildLoopbackRequest(params string[] scopes)
{
var request = new OAuthRequest
{
CodeVerifier = RandomDataBase64Url(32),
Scopes = scopes
};
string codeChallenge = Base64UrlEncodeNoPadding(Sha256(request.CodeVerifier));
const string codeChallengeMethod = "S256";
string scope = BuildScopes(scopes);
request.RedirectUri = string.Format("http://{0}:{1}/", IPAddress.Loopback, GetRandomUnusedPort());
request.State = RandomDataBase64Url(32);
request.AuthorizationRequestUri = string.Format("{0}?response_type=code&scope=openid%20profile{6}&redirect_uri={1}&client_id={2}&state={3}&code_challenge={4}&code_challenge_method={5}",
AuthorizationEndpoint,
Uri.EscapeDataString(request.RedirectUri),
ClientId,
request.State,
codeChallenge,
codeChallengeMethod,
scope);
return(request);
}
private async void HandleRedirect()
{
this.State.Token = null;
// for example, let's pretend I want also want to have access to WebAlbums
var scopes = new[] { "https://picasaweb.google.com/data/" };
var request = OAuthRequest.BuildLoopbackRequest(scopes);
var listener = new HttpListener();
listener.Prefixes.Add(request.RedirectUri);
listener.Start();
// note: add a reference to System.Windows.Presentation and a 'using System.Windows.Threading' for this to compile
await this.Dispatcher.BeginInvoke(new Action(() => { this.Wb.Navigate(request.AuthorizationRequestUri); }));
// here, we'll wait for redirection from our hosted webbrowser
var context = await listener.GetContextAsync();
// browser has navigated to our small http servern answer anything here
string html = "<html><body></body></html>";
var buffer = Encoding.UTF8.GetBytes(html);
context.Response.ContentLength64 = buffer.Length;
var stream = context.Response.OutputStream;
var responseTask = stream.WriteAsync(buffer, 0, buffer.Length).ContinueWith(task =>
{
stream.Close();
listener.Stop();
});
string error = context.Request.QueryString["error"];
if (error != null)
{
return;
}
string state = context.Request.QueryString["state"];
if (state != request.State)
{
return;
}
string code = context.Request.QueryString["code"];
this.State.Token = request.ExchangeCodeForAccessToken(code);
}