Add NOP packet.

DiscImageChef.Devices/Remote/Enums.cs

@@ -1,7 +1,8 @@
 namespace DiscImageChef.Devices.Remote
 {
-    public enum DicPacketType : byte
+    public enum DicPacketType : sbyte
     {
+        Nop = -1,
         Hello = 1,
         CommandListDevices = 2,
         ResponseListDevices = 3

DiscImageChef.Devices/Remote/Remote.cs

@@ -14,8 +14,8 @@ namespace DiscImageChef.Devices.Remote
 {
     public class Remote : IDisposable
     {
-        private readonly Socket _socket;
         private readonly string _host;
+        private readonly Socket _socket;
 
         public Remote(string host)
         {
@@ -54,19 +54,38 @@ namespace DiscImageChef.Devices.Remote
                 throw new ArgumentException();
             }
 
+            byte[] buf;
+
             if (hdr.packetType != DicPacketType.Hello)
+            {
+                if (hdr.packetType != DicPacketType.Nop)
                 {
                     DicConsole.ErrorWriteLine("Expected Hello Packet, got packet type {0}...", hdr.packetType);
                     throw new ArgumentException();
                 }
 
+                buf = new byte[hdr.len];
+                len = _socket.Receive(buf, buf.Length, SocketFlags.None);
+
+                if (len < buf.Length)
+                {
+                    DicConsole.ErrorWriteLine("Could not read from the network...");
+                    throw new IOException();
+                }
+
+                var nop = Marshal.ByteArrayToStructureLittleEndian<DicPacketNop>(buf);
+
+                DicConsole.ErrorWriteLine($"{nop.reason}");
+                throw new ArgumentException();
+            }
+
             if (hdr.version != Consts.PacketVersion)
             {
                 DicConsole.ErrorWriteLine("Unrecognized packet version...");
                 throw new ArgumentException();
             }
 
-            var buf = new byte[hdr.len];
+            buf = new byte[hdr.len];
             len = _socket.Receive(buf, buf.Length, SocketFlags.None);
 
             if (len < buf.Length)
@@ -173,12 +192,29 @@ namespace DiscImageChef.Devices.Remote
             }
 
             if (hdr.packetType != DicPacketType.ResponseListDevices)
+            {
+                if (hdr.packetType != DicPacketType.Nop)
                 {
                     DicConsole.ErrorWriteLine("Expected List Devices Response Packet, got packet type {0}...",
                         hdr.packetType);
                     return new DeviceInfo[0];
                 }
 
+                buf = new byte[hdr.len];
+                len = _socket.Receive(buf, buf.Length, SocketFlags.None);
+
+                if (len < buf.Length)
+                {
+                    DicConsole.ErrorWriteLine("Could not read from the network...");
+                    return new DeviceInfo[0];
+                }
+
+                var nop = Marshal.ByteArrayToStructureLittleEndian<DicPacketNop>(buf);
+
+                DicConsole.ErrorWriteLine($"{nop.reason}");
+                return new DeviceInfo[0];
+            }
+
             if (hdr.version != Consts.PacketVersion)
             {
                 DicConsole.ErrorWriteLine("Unrecognized packet version...");

DiscImageChef.Devices/Remote/Structs.cs

@@ -53,4 +53,17 @@ namespace DiscImageChef.Devices.Remote
         public readonly DicPacketHeader hdr;
         public readonly ushort devices;
     }
+
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
+    public struct DicPacketNop
+    {
+        public DicPacketHeader hdr;
+        public byte reasonCode;
+
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
+        public readonly byte[] spare;
+
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
+        public string reason;
+    }
 }