fix: use stdlib IPAddress.IsLoopback

Jellyfin.Networking/Manager/NetworkManager.cs

@@ -464,35 +464,13 @@ namespace Jellyfin.Networking.Manager
         /// <inheritdoc/>
         public bool IsInLocalNetwork(IPObject address)
         {
-            if (address == null)
-            {
-                throw new ArgumentNullException(nameof(address));
-            }
-
-            if (address.Equals(IPAddress.None))
-            {
-                return false;
-            }
-
-            // See conversation at https://github.com/jellyfin/jellyfin/pull/3515.
-            if (TrustAllIP6Interfaces && address.AddressFamily == AddressFamily.InterNetworkV6)
-            {
-                return true;
-            }
-
-            // As private addresses can be redefined by Configuration.LocalNetworkAddresses
-            return address.IsLoopback() || (_lanSubnets.ContainsAddress(address) && !_excludedSubnets.ContainsAddress(address));
+            return IsInLocalNetwork(address.Address);
         }
 
         /// <inheritdoc/>
         public bool IsInLocalNetwork(string address)
         {
-            if (IPHost.TryParse(address, out IPHost ep))
-            {
-                return _lanSubnets.ContainsAddress(ep) && !_excludedSubnets.ContainsAddress(ep);
-            }
-
-            return false;
+            return IPHost.TryParse(address, out IPHost ipHost) && IsInLocalNetwork(ipHost);
         }
 
         /// <inheritdoc/>
@@ -503,6 +481,11 @@ namespace Jellyfin.Networking.Manager
                 throw new ArgumentNullException(nameof(address));
             }
 
+            if (address.Equals(IPAddress.None))
+            {
+                return false;
+            }
+
             // See conversation at https://github.com/jellyfin/jellyfin/pull/3515.
             if (TrustAllIP6Interfaces && address.AddressFamily == AddressFamily.InterNetworkV6)
             {
@@ -510,7 +493,7 @@ namespace Jellyfin.Networking.Manager
             }
 
             // As private addresses can be redefined by Configuration.LocalNetworkAddresses
-            return _lanSubnets.ContainsAddress(address) && !_excludedSubnets.ContainsAddress(address);
+            return IPAddress.IsLoopback(address) || (_lanSubnets.ContainsAddress(address) && !_excludedSubnets.ContainsAddress(address));
         }
 
         /// <inheritdoc/>

MediaBrowser.Common/Net/IPObject.cs

@@ -65,7 +65,7 @@ namespace MediaBrowser.Common.Net
                 address = address.MapToIPv4();
             }
 
-            if (IsLoopback(address))
+            if (IPAddress.IsLoopback(address))
             {
                 return (address, prefixLength);
             }
@@ -102,31 +102,6 @@ namespace MediaBrowser.Common.Net
             return (new IPAddress(addressBytes), prefixLength);
         }
 
-        /// <summary>
-        /// Tests to see if the ip address is a Loopback address.
-        /// </summary>
-        /// <param name="address">Value to test.</param>
-        /// <returns>True if it is.</returns>
-        public static bool IsLoopback(IPAddress address)
-        {
-            if (address == null)
-            {
-                throw new ArgumentNullException(nameof(address));
-            }
-
-            if (!address.Equals(IPAddress.None))
-            {
-                if (address.IsIPv4MappedToIPv6)
-                {
-                    address = address.MapToIPv4();
-                }
-
-                return address.Equals(IPAddress.Loopback) || address.Equals(IPAddress.IPv6Loopback);
-            }
-
-            return false;
-        }
-
         /// <summary>
         /// Tests to see if the ip address is an IP6 address.
         /// </summary>
@@ -295,7 +270,7 @@ namespace MediaBrowser.Common.Net
         /// <returns>True if it is.</returns>
         public virtual bool IsLoopback()
         {
-            return IsLoopback(Address);
+            return IPAddress.IsLoopback(Address);
         }
 
         /// <summary>