From e811cd7caf434acd84645af8bd05248b54c65c39 Mon Sep 17 00:00:00 2001
From: Shadowghost <Ghost_of_Stone@web.de>
Date: Wed, 13 May 2026 13:47:56 +0200
Subject: [PATCH] Prevent unecessary log spam in NetworkUtils

---
 MediaBrowser.Common/Net/NetworkUtils.cs       |  9 ++-
 .../NetworkParseTests.cs                      | 59 +++++++++++++++++++
 2 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/MediaBrowser.Common/Net/NetworkUtils.cs b/MediaBrowser.Common/Net/NetworkUtils.cs
index 71539b8b78..25a1022d4e 100644
--- a/MediaBrowser.Common/Net/NetworkUtils.cs
+++ b/MediaBrowser.Common/Net/NetworkUtils.cs
@@ -180,9 +180,16 @@ public static partial class NetworkUtils
         List<IPData>? tmpResult = null;
         for (int a = 0; a < values.Length; a++)
         {
+            // Skip entries whose '!' polarity doesn't match this pass
+            var trimmed = values[a].AsSpan().Trim();
+            if (trimmed.StartsWith('!') != negated)
+            {
+                continue;
+            }
+
             if (TryParseToSubnet(values[a], out var innerResult, negated))
             {
-                (tmpResult ??= new()).Add(innerResult);
+                (tmpResult ??= []).Add(innerResult);
             }
             else
             {
diff --git a/tests/Jellyfin.Networking.Tests/NetworkParseTests.cs b/tests/Jellyfin.Networking.Tests/NetworkParseTests.cs
index 66eec077dc..1f523f7f21 100644
--- a/tests/Jellyfin.Networking.Tests/NetworkParseTests.cs
+++ b/tests/Jellyfin.Networking.Tests/NetworkParseTests.cs
@@ -135,6 +135,65 @@ namespace Jellyfin.Networking.Tests
                 Times.Once);
         }
 
+        /// <summary>
+        /// Verifies that IPv4 entries whose '!' polarity doesn't match the requested pass are skipped silently,
+        /// not logged as invalid. Callers parse the same list twice (LAN and excluded) so the off-polarity
+        /// entries are expected, not erroneous.
+        /// </summary>
+        [Fact]
+        public static void TryParseToSubnets_PolarityMismatchIPv4_DoesNotWarn()
+        {
+            var logger = new Mock<ILogger>();
+            var values = new[] { "127.0.0.0/8", "192.168.178.0/24", "!10.0.0.0/8" };
+
+            // Non-negated pass picks up the two non-'!' entries and ignores '!10.0.0.0/8' silently.
+            Assert.True(NetworkUtils.TryParseToSubnets(values, out var lanResult, false, logger.Object));
+            Assert.NotNull(lanResult);
+            Assert.Equal(2, lanResult.Count);
+
+            // Negated pass picks up the single '!' entry and ignores the others silently.
+            Assert.True(NetworkUtils.TryParseToSubnets(values, out var excludedResult, true, logger.Object));
+            Assert.NotNull(excludedResult);
+            Assert.Single(excludedResult);
+
+            logger.Verify(
+                l => l.Log(
+                    LogLevel.Warning,
+                    It.IsAny<EventId>(),
+                    It.IsAny<It.IsAnyType>(),
+                    It.IsAny<Exception>(),
+                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()),
+                Times.Never);
+        }
+
+        /// <summary>
+        /// Same as the IPv4 case but for IPv6 entries — makes sure the polarity pre-check works
+        /// for IPv6 CIDR notation (with '::') as well.
+        /// </summary>
+        [Fact]
+        public static void TryParseToSubnets_PolarityMismatchIPv6_DoesNotWarn()
+        {
+            var logger = new Mock<ILogger>();
+            var values = new[] { "fd00::/8", "fe80::/10", "!fd12:3456:789a::/48" };
+
+            Assert.True(NetworkUtils.TryParseToSubnets(values, out var lanResult, false, logger.Object));
+            Assert.NotNull(lanResult);
+            Assert.Equal(2, lanResult.Count);
+
+            Assert.True(NetworkUtils.TryParseToSubnets(values, out var excludedResult, true, logger.Object));
+            Assert.NotNull(excludedResult);
+            Assert.Single(excludedResult);
+
+            logger.Verify(
+                l => l.Log(
+                    LogLevel.Warning,
+                    It.IsAny<EventId>(),
+                    It.IsAny<It.IsAnyType>(),
+                    It.IsAny<Exception>(),
+                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()),
+                Times.Never);
+        }
+
         /// <summary>
         /// Checks if IPv4 address is within a defined subnet.
         /// </summary>