Packet filtering for those who never finish the handshake

This also kicks those who never finish handshaking upon chat now. (To free up the resources a bit I guess?)

Before a player finishes the connection handshake, the server will check if it's necessary to send them a packet - it checks against a list of necessary packets like:

- ContinueConnecting (Send User Slot),
- PlayerSpawnSelf (CompleteConnectionAndSpawn),
- WorldInfo (Which the server does a further check if the player is at the appropriate state to be sent the world info)
- Status
- Disconnection
- TileFrameSection & TileSendSection

TShockAPI/TSPlayer.cs

@@ -2102,6 +2102,28 @@ namespace TShockAPI
 			SendData(PacketTypes.PlayerAddBuff, number: Index, number2: type, number3: time);
 		}
 
+
+		/// <summary>
+		/// Determines if an outgoing packet is necessary to send to a player before they have finished the connection handshake.
+		/// </summary>
+		/// <param name="msgType">The packet type to check against the necessary list.</param>
+		/// <returns></returns>
+		private bool NecessaryPacket(PacketTypes msgType)
+		{
+			List<PacketTypes> ConnectionPackets = new List<PacketTypes>()
+			{
+				PacketTypes.ContinueConnecting,
+				PacketTypes.WorldInfo,
+				PacketTypes.Status,
+				PacketTypes.Disconnect,
+				PacketTypes.TileFrameSection,
+				PacketTypes.TileSendSection,
+				PacketTypes.PlayerSpawnSelf
+			};
+
+			return ConnectionPackets.Contains(msgType);
+		}
+
 		//Todo: Separate this into a few functions. SendTo, SendToAll, etc
 		/// <summary>
 		/// Sends data to the player.
@@ -2119,6 +2141,12 @@ namespace TShockAPI
 			if (RealPlayer && !ConnectionAlive)
 				return;
 
+			if (!NecessaryPacket(msgType) && !FinishedHandshake)
+				return;
+
+			if (msgType == PacketTypes.WorldInfo && State < 3) //If the player has requested the world data, their state will be 3.
+				return;
+
 			NetMessage.SendData((int)msgType, Index, -1, text == null ? null : NetworkText.FromLiteral(text), number, number2, number3, number4, number5);
 		}
 

TShockAPI/TShock.cs

@@ -1494,6 +1494,7 @@ namespace TShockAPI
 
 			if (!tsplr.FinishedHandshake)
 			{
+				tsplr.Kick(GetString("Your client didn't finish the handshake."), true);
 				args.Handled = true;
 				return;
 			}