From 3e0cfd3af36f024b685ed512d4fa5f8c9b3fbe59 Mon Sep 17 00:00:00 2001
From: Luke Pulverenti <luke.pulverenti@gmail.com>
Date: Wed, 11 Oct 2017 00:45:21 -0400
Subject: [PATCH] fixes #1769 - IsInLocalNetwork returns wrong value

---
 .../Networking/NetworkManager.cs              | 57 +++++++++++++++++--
 1 file changed, 52 insertions(+), 5 deletions(-)

diff --git a/Emby.Server.Implementations/Networking/NetworkManager.cs b/Emby.Server.Implementations/Networking/NetworkManager.cs
index 7f0eef0b9f..66b2cba39b 100644
--- a/Emby.Server.Implementations/Networking/NetworkManager.cs
+++ b/Emby.Server.Implementations/Networking/NetworkManager.cs
@@ -81,8 +81,18 @@ namespace Emby.Server.Implementations.Networking
                 return true;
             }
 
-            // Handle ipv4 mapped to ipv6
-            endpoint = endpoint.Replace("::ffff:", string.Empty);
+            // ipv6
+            if (endpoint.Split('.').Length > 4)
+            {
+                // Handle ipv4 mapped to ipv6
+                var originalEndpoint = endpoint;
+                endpoint = endpoint.Replace("::ffff:", string.Empty);
+
+                if (string.Equals(endpoint, originalEndpoint, StringComparison.OrdinalIgnoreCase))
+                {
+                    return false;
+                }
+            }
 
             // Private address space:
             // http://en.wikipedia.org/wiki/Private_network
@@ -92,13 +102,15 @@ namespace Emby.Server.Implementations.Networking
                 return Is172AddressPrivate(endpoint);
             }
 
-            return
-                endpoint.StartsWith("localhost", StringComparison.OrdinalIgnoreCase) ||
+            return endpoint.StartsWith("localhost", StringComparison.OrdinalIgnoreCase) ||
+                endpoint.StartsWith("127.0.0.1", StringComparison.OrdinalIgnoreCase) ||
                 IsInPrivateAddressSpaceAndLocalSubnet(endpoint);
         }
 
         public bool IsInPrivateAddressSpaceAndLocalSubnet(string endpoint)
         {
+            var endpointFirstPart = endpoint.Split('.')[0];
+
             string subnet_Match = "";
             if (
                 endpoint.StartsWith("127.", StringComparison.OrdinalIgnoreCase) ||
@@ -109,7 +121,7 @@ namespace Emby.Server.Implementations.Networking
             {
                 foreach (NetworkInterface adapter in NetworkInterface.GetAllNetworkInterfaces())
                     foreach (UnicastIPAddressInformation unicastIPAddressInformation in adapter.GetIPProperties().UnicastAddresses)
-                        if (unicastIPAddressInformation.Address.AddressFamily == AddressFamily.InterNetwork && endpoint.Split('.')[0] == unicastIPAddressInformation.Address.ToString().Split('.')[0])
+                        if (unicastIPAddressInformation.Address.AddressFamily == AddressFamily.InterNetwork && endpointFirstPart == unicastIPAddressInformation.Address.ToString().Split('.')[0])
                         {
                             int subnet_Test = 0;
                             foreach (string part in unicastIPAddressInformation.IPv4Mask.ToString().Split('.'))
@@ -125,6 +137,41 @@ namespace Emby.Server.Implementations.Networking
             return endpoint.StartsWith(subnet_Match + ".", StringComparison.OrdinalIgnoreCase);
         }
 
+        private Dictionary<string, string> _subnetLookup = new Dictionary<string, string>(StringComparer.Ordinal);
+        private string GetSubnet(string endpointFirstPart)
+        {
+            string subnet_Match = "";
+
+            lock (_subnetLookup)
+            {
+                if (_subnetLookup.TryGetValue(endpointFirstPart, out subnet_Match))
+                {
+                    return subnet_Match;
+                }
+
+                foreach (NetworkInterface adapter in NetworkInterface.GetAllNetworkInterfaces())
+                    foreach (UnicastIPAddressInformation unicastIPAddressInformation in adapter.GetIPProperties().UnicastAddresses)
+                        if (unicastIPAddressInformation.Address.AddressFamily == AddressFamily.InterNetwork && endpointFirstPart == unicastIPAddressInformation.Address.ToString().Split('.')[0])
+                        {
+                            int subnet_Test = 0;
+                            foreach (string part in unicastIPAddressInformation.IPv4Mask.ToString().Split('.'))
+                            {
+                                if (part.Equals("0")) break;
+                                subnet_Test++;
+                            }
+
+                            subnet_Match = String.Join(".", unicastIPAddressInformation.Address.ToString().Split('.').Take(subnet_Test).ToArray());
+                        }
+
+                if (!string.IsNullOrWhiteSpace(subnet_Match))
+                {
+                    _subnetLookup[endpointFirstPart] = subnet_Match;
+                }
+            }
+
+            return subnet_Match;
+        }
+
         private bool Is172AddressPrivate(string endpoint)
         {
             for (var i = 16; i <= 31; i++)