Fix subnet contains check

We are still using `Subnet.Contains` a lot but that does not handle IPv4 mapped to IPv6 addresses at all. It was partially fixed by #12094 in local network checking, but it may not always happen on LAN.

Also make all local network checking to use IsInLocalNetwork method instead of just performing `Subnet.Contains` which is not accurate.

Filter out all link-local addresses for external interface matching.

1 files changed, 19 insertions, 0 deletions

diff --git a/MediaBrowser.Common/Net/NetworkUtils.cs b/MediaBrowser.Common/Net/NetworkUtils.cs
index 738096352..e21fdeb3d 100644
--- a/MediaBrowser.Common/Net/NetworkUtils.cs
+++ b/MediaBrowser.Common/Net/NetworkUtils.cs
@@ -326,4 +326,23 @@ public static partial class NetworkUtils
 
         return new IPAddress(BitConverter.GetBytes(broadCastIPAddress));
     }
+
+    /// <summary>
+    /// Check if a subnet contains an address. This method also handles IPv4 mapped to IPv6 addresses.
+    /// </summary>
+    /// <param name="network">The <see cref="IPNetwork"/>.</param>
+    /// <param name="address">The <see cref="IPAddress"/>.</param>
+    /// <returns>Whether the supplied IP is in the supplied network.</returns>
+    public static bool SubNetContainsAddress(IPNetwork network, IPAddress address)
+    {
+        ArgumentNullException.ThrowIfNull(address);
+        ArgumentNullException.ThrowIfNull(network);
+
+        if (address.IsIPv4MappedToIPv6)
+        {
+            address = address.MapToIPv4();
+        }
+
+        return network.Contains(address);
+    }
 }