ShareX/ShareX.UploadersLib/OAuth/OAuthListener.cs

#region License Information (GPL v3)

/*
    ShareX - A program that allows you to take screenshots and share any file type
    Copyright (c) 2007-2022 ShareX Team

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

    Optionally you can also view the license at <http://www.gnu.org/licenses/>.
*/

#endregion License Information (GPL v3)

using ShareX.HelpersLib;
using ShareX.UploadersLib.Properties;
using System;
using System.IO;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace ShareX.UploadersLib
{
    public class OAuthListener
    {
        public IOAuth2 OAuth { get; private set; }

        public async Task<string> ConnectAsync()
        {
            IPAddress ip = IPAddress.Loopback;
            int port = URLHelpers.GetRandomUnusedPort();
            string redirectURI = string.Format($"http://{ip}:{port}/");
            URLHelpers.OpenURL(redirectURI + "?code=test");

            try
            {
                using (HttpListener listener = new HttpListener())
                {
                    listener.Prefixes.Add(redirectURI);
                    listener.Start();

                    HttpListenerContext context = await listener.GetContextAsync();
                    string code = context.Request.QueryString.Get("code");

                    using (HttpListenerResponse response = context.Response)
                    {
                        string status;

                        if (!string.IsNullOrEmpty(code))
                        {
                            status = "Authorization completed successfully.";
                        }
                        else
                        {
                            status = "Authorization did not succeed.";
                        }

                        string responseText = Resources.OAuthCallbackPage.Replace("{0}", status);
                        byte[] buffer = Encoding.UTF8.GetBytes(responseText);
                        response.ContentLength64 = buffer.Length;
                        response.KeepAlive = false;

                        using (Stream responseOutput = response.OutputStream)
                        {
                            await responseOutput.WriteAsync(buffer, 0, buffer.Length);
                            await responseOutput.FlushAsync();
                        }
                    }

                    return code;
                }
            }
            catch (Exception e)
            {
                DebugHelper.WriteException(e);
            }

            return null;
        }
    }
}