When Client sends message longer than 256 bytes, kick him instead of handling message (#4514)

* Wrong overload of function push() got called when pushing a cEntity*.
Using a const cEntity * fixes this.

* Fixed accidental wrong indentation

* Compiler didn't like old style cast

* Kicking player when writing chat message longer than 2048

* Accounted for Astrings size() method returning bits, not bytes

* Fixed typo

* Changed MAX_STRING_SIZE to 1024, removed unnecessary division by 8

* Handling message length check in cClientHandle:HandleChat

* Guard clause instead of if else

* Remove stale changes

* Fixed formatting

Co-authored-by: mluchterhand <mluchterhand@max.de>
Co-authored-by: Peter Bell <peterbell10@live.co.uk>
Co-authored-by: Mattes D <github@xoft.cz>

src/ClientHandle.cpp

@@ -43,6 +43,9 @@
 /** Maximum number of block change interactions a player can perform per tick - exceeding this causes a kick */
 #define MAX_BLOCK_CHANGE_INTERACTIONS 20
 
+/** Maximum number of bytes that a chat message sent by a player may consist of */
+#define MAX_CHAT_MSG_LENGTH 1024
+
 /** The interval for sending pings to clients.
 Vanilla sends one ping every 1 second. */
 static const std::chrono::milliseconds PING_TIME_MS = std::chrono::milliseconds(1000);
@@ -1549,6 +1552,13 @@ void cClientHandle::HandleRightClick(int a_BlockX, int a_BlockY, int a_BlockZ, e
 
 void cClientHandle::HandleChat(const AString & a_Message)
 {
+	if ((a_Message.size()) > MAX_CHAT_MSG_LENGTH)
+	{
+		this->Kick(std::string("Please don't exceed the maximum message length of ")
+			+ std::to_string(MAX_CHAT_MSG_LENGTH)
+		);
+		return;
+	}
 	// We no longer need to postpone message processing, because the messages already arrive in the Tick thread
 
 	// If a command, perform it: