sm-ext-A2SFixes/extension.cpp

/**
 * vim: set ts=4 :
 * =============================================================================
 * SourceMod A2SFixes Extension
 * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
 * =============================================================================
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, version 3.0, as published by the
 * Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * As a special exception, AlliedModders LLC gives you permission to link the
 * code of this program (as well as its derivative works) to "Half-Life 2," the
 * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software
 * by the Valve Corporation.  You must obey the GNU General Public License in
 * all respects for all other code used.  Additionally, AlliedModders LLC grants
 * this exception to all derivative works.  AlliedModders LLC defines further
 * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
 * or <http://www.sourcemod.net/license.php>.
 *
 * Version: $Id$
 */

#include "extension.h"
#include "string.h"
#include "sys/socket.h"
#include "CDetour/detours.h"

#define DETOUR_CREATE_MEMBER_ADDRESS(name, address) CDetourManager::CreateDetour(GET_MEMBER_CALLBACK(name), GET_MEMBER_TRAMPOLINE(name), address);
#define DETOUR_CREATE_STATIC_ADDRESS(name, address) CDetourManager::CreateDetour(GET_STATIC_CALLBACK(name), GET_STATIC_TRAMPOLINE(name), address);

#define A2S_INFO_REQUEST    "\xFF\xFF\xFF\xFF\x54"
#define A2S_INFO_REPLY      "\xFF\xFF\xFF\xFF\x49"

#define A2S_PLAYER_REQUEST  "\xFF\xFF\xFF\xFF\x55"
#define A2S_PLAYER_REPLY    "\xFF\xFF\xFF\xFF\x44"

/**
 * @file extension.cpp
 * @brief Implement extension code here.
 */

A2SFixes g_Interface;
SMEXT_LINK(&g_Interface);

CDetour *g_pDetour_SendTo = NULL;
CDetour *g_pDetour_RecvFrom = NULL;

/**
 * @brief
 */
DETOUR_DECL_STATIC6(Detour_SendTo, int, int, s, char *, buf, int, len, int, flags, sockaddr *, to, socklen_t*, tolen)
{
	if (memcmp(buf, A2S_INFO_REPLY, 5) == 0)
	{
//		g_pSM->LogMessage(myself, "A2S_INFO_REPLY: %s", buf);

		char *NewBuf;
		char *OldBuf;

		NewBuf = new char[len];
		memcpy(NewBuf, buf, len);
		OldBuf = NewBuf;

		// Skip header and protocol
		NewBuf += 5;

		// Skip server name
		while(*NewBuf)
			NewBuf++;

		NewBuf++;

		// Skip map name
		while(*NewBuf)
			NewBuf++;

		NewBuf++;

		// Skip folder
		while(*NewBuf)
			NewBuf++;

		NewBuf++;

		// Skip game name
		while(*NewBuf)
			NewBuf++;

		NewBuf++;

		// Skip game id
		NewBuf += 2;

		// Calculate playercount
		int iPlayers = 0;

		for (int index = 0; index <= SM_MAXPLAYERS; index++)
		{
			IGamePlayer *pPlayer = playerhelpers->GetGamePlayer(index);

			if (pPlayer != NULL && pPlayer->IsConnected() && !pPlayer->IsSourceTV())
			{
				iPlayers += 1;
			}
		}

		// Correct playercount
		memset(NewBuf, iPlayers, 1);

		// Reset Pointer
		NewBuf = OldBuf;

		return DETOUR_STATIC_CALL(Detour_SendTo)(s, NewBuf, len, flags, to, tolen);
	}

//	if (memcmp(buf, A2S_PLAYER_REPLY, 5) == 0)
//	{
//		g_pSM->LogMessage(myself, "A2S_PLAYER_REPLY: %s", buf);
//	}

	return DETOUR_STATIC_CALL(Detour_SendTo)(s, buf, len, flags, to, tolen);
}

/**
 * @brief
 */
DETOUR_DECL_STATIC6(Detour_RecvFrom, int, int, s, char *, buf, int, len, int, flags, sockaddr *, from, socklen_t*, fromlen)
{
//	if (memcmp(buf, A2S_INFO_REQUEST, 5) == 0)
//	{
//		g_pSM->LogMessage(myself, "A2S_INFO_REQUEST: %s", buf);
//	}

//	if (memcmp(buf, A2S_PLAYER_REQUEST, 5) == 0)
//	{
//		g_pSM->LogMessage(myself, "A2S_PLAYER_REQUEST: %s", buf);
//	}

	return DETOUR_STATIC_CALL(Detour_RecvFrom)(s, buf, len, flags, from, fromlen);
}

/**
 * @brief This is called after the initial loading sequence has been processed.
 *
 * @param error		Error message buffer.
 * @param maxlength	Size of error message buffer.
 * @param late		Whether or not the module was loaded after map load.
 * @return			True to succeed loading, false to fail.
 */
bool A2SFixes::SDK_OnLoad(char *error, size_t maxlength, bool late)
{
	CDetourManager::Init(g_pSM->GetScriptingEngine(), NULL);

	g_pDetour_SendTo = DETOUR_CREATE_STATIC_ADDRESS(Detour_SendTo, (void*)sendto);

	if (g_pDetour_SendTo == NULL)
	{
		snprintf(error, maxlength, "Could not create detour for 'sendto'");
		SDK_OnUnload();
		return false;
	}

	g_pDetour_RecvFrom = DETOUR_CREATE_STATIC_ADDRESS(Detour_RecvFrom, (void*)recvfrom);

	if (g_pDetour_RecvFrom == NULL)
	{
		snprintf(error, maxlength, "Could not create detour for 'recvfrom'");
		SDK_OnUnload();
		return false;
	}

	g_pDetour_SendTo->EnableDetour();
	g_pDetour_RecvFrom->EnableDetour();
	return true;
}

/**
 * @brief This is called right before the extension is unloaded.
 */
void A2SFixes::SDK_OnUnload()
{
	if(g_pDetour_SendTo != NULL)
	{
		g_pDetour_SendTo->Destroy();
		g_pDetour_SendTo = NULL;
	}

	if(g_pDetour_RecvFrom != NULL)
	{
		g_pDetour_RecvFrom->Destroy();
		g_pDetour_RecvFrom = NULL;
	}
}