UserCmd strings

From Valve Developer Community

This modification allows a mod to send messages from the client to the server without using commands. This allows for a more secure method of communication from the client to the server. A possible implementation would be with VGUI Screens.

 Note: This method should only be used on multiplayer servers, where cheating has a negative effect on gameplay.

Changes

UserCmd.cpp

Note how WriteUsercmd only writes data if there is a delta (change). Notice how the count is tested, the data is then sent, and all of the saved data is then purged. This means only delta data will be sent.

WriteUsercmd

At the end:

	C_BasePlayer *pLocalPlayer = C_BasePlayer::GetLocalPlayer();
	byte count = pLocalPlayer->GetUserDataCount();
	if(count)
	{
		buf->WriteOneBit( 1 );

		buf->WriteByte(count);

		for(byte x=0;x<count;x++)
		{
			buf->WriteString(pLocalPlayer->GetUserData(x));
		}

		pLocalPlayer->ClearUserData();
	}
	else
	{
		buf->WriteOneBit( 0 );
	}

ReadUsercmd

void ReadUsercmd( bf_read *buf, CUserCmd *move, CUserCmd *from, CBasePlayer *pPlayer /*= NULL*/ )

At the end:

	if( buf->ReadOneBit() )
	{
		int count = buf->ReadByte();
		for(int x=0;x<count;x++)
		{
			bool bOverflow = false;
			char *cmd = buf->ReadAndAllocateString(&bOverflow);
			Assert(!bOverflow);
#ifndef CLIENT_DLL
			Assert(pPlayer);
			pPlayer->EvaluateUserData(cmd);
#endif
			delete cmd;
		}
	}

UserCmd.h

#include "baseplayer_shared.h"

void ReadUsercmd( bf_read *buf, CUserCmd *move, CUserCmd *from, CBasePlayer *pPlayer = NULL );

Changes to gameinterface.cpp

ReadUsercmd( buf, to, from, pPlayer );

Implementation

C_BasePlayer

• protected CUtlLinkedList<const char *, byte> m_UserData stores all of the data to send (The player should never have to send over 255 strings for 1 usercmd).
• public void AddUserData(const char *pNewData) adds data to send.
• public byte GetUserDataCount(void) returns m_UserData.Count().
• public const char *GetUserData(byte index) returns m_UserData.Element(index).
• public void ClearUserData(void) calls m_UserData.PurgeAndDeleteElements(). See strdup to make sure you don't accidentally get any null pointers.

CBasePlayer

• public void EvaluateUserData(const char *pData) evaluates what to do with the command stored in pData.