Fix OneDriveGraphApi when use custom redirect url error.

[kgamecarter]

Fix issue #18

[KoenZomers]

Thanks for your contribution. I would like to test this first as it really should not be necessary to provide a client secret. Can you provide me with more detailed steps on how to reproduce the issue please?

[kgamecarter]

Create new Azure AD application. Add custom redirect url.

In ASP.NET Core MVC project.

private static OneDriveGraphApi oneDriveApi = new OneDriveGraphApi("4f205cff-965c-4f5e-b867-f5e27721c2db");

public async Task<IActionResult> AuthOneDrive()
{
    oneDriveApi.AuthenticationRedirectUrl = "https://localhost:44307/Home/ParseToken";
    return Redirect(oneDriveApi.GetAuthenticationUri().AbsoluteUri);
}

public async Task<IActionResult> ParseToken()
{
    var url = Microsoft.AspNetCore.Http.Extensions.UriHelper.GetDisplayUrl(Request);
    var authToken = oneDriveApi.GetAuthorizationTokenFromUrl(url);
    try
    {
        var token = await oneDriveApi.GetAccessToken();
        return RedirectToAction("Index");
    }
    catch(TokenRetrievalFailedException e) // The request body must contain the following parameter: 'client_assertion' or 'client_secret'.
    { }
    return BadRequest();
}