Address SteamRE/SteamKit#455

ArchiSteamFarm/GlobalConfig.cs

@@ -101,9 +101,6 @@ internal sealed class GlobalConfig {
 		[JsonProperty(Required = Required.DisallowNull)]
 		internal readonly bool Statistics = true;
 
-		[JsonProperty(Required = Required.DisallowNull)]
-		internal readonly ProtocolTypes SteamProtocols = ProtocolTypes.Tcp;
-
 		[JsonProperty(Required = Required.DisallowNull)]
 		internal readonly EUpdateChannel UpdateChannel = EUpdateChannel.Stable;
 
@@ -125,6 +122,9 @@ internal string SSteamOwnerID {
 		[JsonProperty(Required = Required.DisallowNull)]
 		internal ulong SteamOwnerID { get; private set; }
 
+		[JsonProperty(Required = Required.DisallowNull)]
+		internal ProtocolTypes SteamProtocols { get; private set; } = ProtocolTypes.Tcp;
+
 		// This constructor is used only by deserializer
 		private GlobalConfig() { }
 
@@ -174,6 +174,13 @@ internal static GlobalConfig Load(string filePath) {
 				return null;
 			}
 
+			if (globalConfig.SteamProtocols.HasFlag(ProtocolTypes.WebSocket) && !OS.SupportsWebSockets()) {
+				globalConfig.SteamProtocols &= ProtocolTypes.WebSocket;
+				if (globalConfig.SteamProtocols == 0) {
+					globalConfig.SteamProtocols = ProtocolTypes.Tcp;
+				}
+			}
+
 			GlobalConfig result = globalConfig;
 			return result;
 		}

ArchiSteamFarm/OS.cs

@@ -24,6 +24,7 @@ limitations under the License.
 
 using System;
 using System.IO;
+using System.Net.WebSockets;
 using System.Runtime.InteropServices;
 using ArchiSteamFarm.Localization;
 
@@ -45,6 +46,17 @@ internal static void Init(bool headless) {
 			}
 		}
 
+		// TODO: We should really get rid of this once https://github.com/SteamRE/SteamKit/issues/455 or https://github.com/dotnet/corefx/issues/9503 is solved
+		internal static bool SupportsWebSockets() {
+			try {
+				using (new ClientWebSocket()) {
+					return true;
+				}
+			} catch (PlatformNotSupportedException) {
+				return false;
+			}
+		}
+
 		internal static void UnixSetFileAccessExecutable(string path) {
 			if (string.IsNullOrEmpty(path) || !File.Exists(path)) {
 				ASF.ArchiLogger.LogNullError(nameof(path));