How to programmatically get the Authorization code without requiring the user approval in OAuth 2.0

Hi Здравко 

Thank you for provided information

I faced with following problem 

In console application everything works fine and token successfully generated

Here I attach body of the await methods

Some important notes : 

RedirectUri variable is local host

redirectUri is bariable with value that DropBox returns to me with approve code

The rest part of the code is same to the example that is provided in documentation

The problem is that this code does not work in my Application. It stops at Proce/ssCodeFlowAsync method and after that the eternal loading of response begins. Sometimes eternal loading begins at HandleJSRedirect and HandleOAuth2Redirect methods, I do not know what causes such behavior.

I want to mention that in  Console Application everything works great, without any troubles, but when I execute same code in my project app - eternal loading always starts, it looks like some troubles with threads, but I do not know what is wrong.

Here is my code in text

var http = new HttpListener();
http.Prefixes.Add(LoopbackHost);
http.Start();

var state = Guid.NewGuid().ToString("N");
var authorizeUri = DropboxOAuth2Helper.GetAuthorizeUri(OAuthResponseType.Code, ApiKey,
RedirectUri, state: state, tokenAccessType: TokenAccessType.Offline, scopeList: scopeList, includeGrantedScopes: includeGrantedScopes);

System.Diagnostics.Process.Start(authorizeUri.ToString());

// Handle OAuth redirect and send URL fragment to local server using JS.
await HandleOAuth2Redirect(http);

// Handle redirect from JS and process OAuth response.
var redirectUri = await HandleJSRedirect(http);

var tokenResult = await DropboxOAuth2Helper.ProcessCodeFlowAsync(redirectUri, ApiKey, ApiSecret, RedirectUri.ToString(), state);
Console.WriteLine("Finished Exchanging Code for Token");
string Access = tokenResult.AccessToken;

-------------------------------------------------------------------------------

private async Task<Uri> HandleJSRedirect(HttpListener http)
{
var context = await http.GetContextAsync();
// We only care about request to TokenRedirectUri endpoint.
//while (context.Request.Url.AbsolutePath != JSRedirectUri.AbsolutePath)
//{
// context = await http.GetContextAsync();
//}
Uri redirectUri = new Uri(context.Request.UrlReferrer.ToString());
return redirectUri;
}
private async Task HandleOAuth2Redirect(HttpListener http)
{
var context = await http.GetContextAsync();
// We only care about request to RedirectUri endpoint.
while (context.Request.Url.AbsolutePath != RedirectUri.AbsolutePath)
{
context = await http.GetContextAsync();
}
//context.Response.ContentType = "text/html";
//Respond with a page which runs JS and sends URL fragment as query string
//to TokenRedirectUri.
//using (var file = File.OpenRead("index.html"))
//{
// file.CopyTo(context.Response.OutputStream);
//}
context.Response.OutputStream.Close();
}