httpclient: treat "refresh" as redirect (#15646)

src/Jackett.Common/Utils/Clients/WebClient.cs

@@ -5,6 +5,7 @@ using System.Net;
 using System.Net.Http;
 using System.Net.Http.Headers;
 using System.Text;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using System.Web;
 using com.LandonKey.SocksWebProxy;
@@ -17,6 +18,8 @@ namespace Jackett.Common.Utils.Clients
 {
     public abstract class WebClient : IObserver<ServerConfig>
     {
+        private static readonly Regex _RefreshHeaderRegex = new Regex("^(.*?url)=(.*?)(?:;|$)", RegexOptions.Compiled);
+
         protected IDisposable ServerConfigUnsubscriber;
         protected Logger logger;
         protected IConfigurationService configService;
@@ -263,5 +266,31 @@ namespace Jackett.Common.Utils.Clients
             content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
             return content;
         }
+
+        protected static Uri RedirectUri(HttpResponseMessage response)
+        {
+            var newUri = response.Headers.Location;
+
+            if (newUri == null && response.Headers.TryGetValues("Refresh", out var refreshHeaders))
+            {
+                var refreshHeader = refreshHeaders.FirstOrDefault();
+
+                if (refreshHeader == null)
+                {
+                    return null;
+                }
+
+                var match = _RefreshHeaderRegex.Match(refreshHeader);
+
+                if (match.Success)
+                {
+                    return new Uri(response.RequestMessage.RequestUri, match.Groups[2].Value);
+                }
+
+                return null;
+            }
+
+            return newUri;
+        }
     }
 }