Fix Mono 4.8+

ArchiSteamFarm/Runtime.cs

@@ -127,6 +127,21 @@ namespace ArchiSteamFarm {
 			}
 		}
 
+		// TODO: Remove me once BTLS in Mono 4.8+ is fixed
+		internal static bool RequiresNoCertificateValidation() {
+			if (!IsRunningOnMono) {
+				return false;
+			}
+
+			Version monoVersion = GetMonoVersion();
+
+			if (monoVersion?.Major != 4) {
+				return false;
+			}
+
+			return monoVersion.Minor >= 8;
+		}
+
 		private static Version GetNetVersion() {
 			uint release;
 			using (RegistryKey registryKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32).OpenSubKey("SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full\\")) {

ArchiSteamFarm/WebBrowser.cs

@@ -54,6 +54,10 @@ namespace ArchiSteamFarm {
 			// Don't use Expect100Continue, we're sure about our POSTs, save some TCP packets
 			ServicePointManager.Expect100Continue = false;
 
+			if (Runtime.RequiresNoCertificateValidation()) {
+				ServicePointManager.ServerCertificateValidationCallback += (s, ce, ca, p) => true;
+			}
+
 #if !__MonoCS__
 			// We run Windows-compiled ASF on both Windows and Mono. Normally we'd simply put code in the if
 			// However, if we did that, then we would still crash on Mono due to potentially calling non-existing methods