Fix master server

RageCoop.Server/Server.cs

@@ -141,7 +141,6 @@ namespace RageCoop.Server
                             Logger?.Error(ex.InnerException?.Message ?? ex.Message);
                             return;
                         }
-                        var realMaster = Settings.MasterServer;
                         while (!_stopping)
                         {
                             string msg =
@@ -161,7 +160,8 @@ namespace RageCoop.Server
                             HttpResponseMessage response = null;
                             try
                             {
-                                response = await httpClient.PostAsync(realMaster, new StringContent(msg, Encoding.UTF8, "application/json"));
+                                var realUrl = Util.GetFinalRedirect(Settings.MasterServer);
+                                response = await httpClient.PostAsync(realUrl, new StringContent(msg, Encoding.UTF8, "application/json"));
                             }
                             catch (Exception ex)
                             {

RageCoop.Server/Util.cs

@@ -103,5 +103,65 @@ namespace RageCoop.Server
         {
             return values[new Random().Next(values.Length-1)];
         }
+
+        public static string GetFinalRedirect(string url)
+        {
+            if (string.IsNullOrWhiteSpace(url))
+                return url;
+
+            int maxRedirCount = 8;  // prevent infinite loops
+            string newUrl = url;
+            do
+            {
+                HttpWebRequest req = null;
+                HttpWebResponse resp = null;
+                try
+                {
+                    req = (HttpWebRequest)HttpWebRequest.Create(url);
+                    req.Method = "HEAD";
+                    req.AllowAutoRedirect = false;
+                    resp = (HttpWebResponse)req.GetResponse();
+                    switch (resp.StatusCode)
+                    {
+                        case HttpStatusCode.OK:
+                            return newUrl;
+                        case HttpStatusCode.Redirect:
+                        case HttpStatusCode.MovedPermanently:
+                        case HttpStatusCode.RedirectKeepVerb:
+                        case HttpStatusCode.RedirectMethod:
+                            newUrl = resp.Headers["Location"];
+                            if (newUrl == null)
+                                return url;
+
+                            if (newUrl.IndexOf("://", System.StringComparison.Ordinal) == -1)
+                            {
+                                // Doesn't have a URL Schema, meaning it's a relative or absolute URL
+                                Uri u = new Uri(new Uri(url), newUrl);
+                                newUrl = u.ToString();
+                            }
+                            break;
+                        default:
+                            return newUrl;
+                    }
+                    url = newUrl;
+                }
+                catch (WebException)
+                {
+                    // Return the last known good URL
+                    return newUrl;
+                }
+                catch
+                {
+                    return null;
+                }
+                finally
+                {
+                    if (resp != null)
+                        resp.Close();
+                }
+            } while (maxRedirCount-- > 0);
+
+            return newUrl;
+        }
     }
 }