From 4869559e8201e8a1e8c7dc5a3ecf7c081f059fcd Mon Sep 17 00:00:00 2001
From: Fey <fey@imail.yo3explorer.moe>
Date: Tue, 25 Aug 2026 18:15:26 +0200
Subject: [PATCH] The SSDP M-SEARCH feature can now run on Synology DSM.

---
 .gitignore                                         |  1 +
 .../SimpleServiceDiscoveryProtocol/SsdpClient.cs   | 14 +++++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/.gitignore b/.gitignore
index 2d26019..9553a02 100644
--- a/.gitignore
+++ b/.gitignore
@@ -139,3 +139,4 @@ imgui.ini
 /skyscraper8.Tests.NUnit/obj/Debug/net8.0
 /skyscraper8.Tests.NUnit/obj
 .idea/.idea.skyscraper8/.idea
+/skyscraper8/bin/Release/net8.0/linux-x64
diff --git a/skyscraper8/SimpleServiceDiscoveryProtocol/SsdpClient.cs b/skyscraper8/SimpleServiceDiscoveryProtocol/SsdpClient.cs
index 13a4cc7..bf03811 100644
--- a/skyscraper8/SimpleServiceDiscoveryProtocol/SsdpClient.cs
+++ b/skyscraper8/SimpleServiceDiscoveryProtocol/SsdpClient.cs
@@ -27,14 +27,17 @@ namespace skyscraper8.SimpleServiceDiscoveryProtocol
 		{
 			NetworkInterface[] networkInterfaces = NetworkInterface.GetAllNetworkInterfaces();
 			IPAddress[] ipAddresses = Array.ConvertAll(networkInterfaces, x => GetIPAddress(x));
-			IPEndPoint[] localEndPoints = Array.ConvertAll(ipAddresses, x => new IPEndPoint(x, 1901));
+			IPEndPoint[] localEndPoints = Array.ConvertAll(ipAddresses, x => new IPEndPoint(x, 0));	//don't use port 1901 here. It's used by old SSDP example code but is wrong.
 			IPEndPoint remoteEndPoint = new IPEndPoint(IPAddress.Parse("239.255.255.250"), 1900);
 			Socket[] udpSockets = Array.ConvertAll(localEndPoints,
 				x =>
 				{
 					byte[] addressBytes = x.Address.GetAddressBytes();
-					if (addressBytes[0] == 169)
-						return null;
+					if (addressBytes[0] == 169 || addressBytes.Length != 4)
+					{
+						logger.WarnFormat("The address {0} will not be used because it's network type is not supported.", new IPAddress(addressBytes));
+						return null;
+					}
 					Socket temp = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
 					temp.Bind(x);
 					temp.SendTo(Encoding.UTF8.GetBytes(SEARCH_STRING), SocketFlags.None, remoteEndPoint);
@@ -81,6 +84,11 @@ namespace skyscraper8.SimpleServiceDiscoveryProtocol
 		{
 			IPInterfaceProperties ipProperties = networkInterface.GetIPProperties();
 			UnicastIPAddressInformationCollection addresses = ipProperties.UnicastAddresses;
+			if (addresses.Count == 0)
+			{
+				logger.WarnFormat("Network interface {0} does not have an unicast address.", networkInterface.Name);
+				return IPAddress.Loopback;
+            }
 			UnicastIPAddressInformation[] addressArray = addresses.ToArray();
 			Array.Sort(addressArray, (a, b) => RateIpAddress(b).CompareTo(RateIpAddress(a)));
 			UnicastIPAddressInformation address = addressArray[0];