/**

 * vim: set ts=4 :

 * =============================================================================

 * SourceMod SDKTools 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"

void **g_pGameRules = NULL;

void *g_EntList = NULL;

void InitializeValveGlobals()

{

	g_EntList = gamehelpers->GetGlobalEntityList();

	char *addr;

#ifdef PLATFORM_WINDOWS

	/* g_pGameRules */

	if (!g_pGameConf->GetMemSig("CreateGameRulesObject", (void **)&addr) || !addr)

	{

		return;

	}

	int offset;

	if (!g_pGameConf->GetOffset("g_pGameRules", &offset) || !offset)

	{

		return;

	}

	g_pGameRules = *reinterpret_cast<void ***>(addr + offset);

#elif defined PLATFORM_LINUX

	/* g_pGameRules */

	if (!g_pGameConf->GetMemSig("g_pGameRules", (void **)&addr) || !addr)

	{

		return;

	}

	g_pGameRules = reinterpret_cast<void **>(addr);

#endif

}

size_t UTIL_StringToSignature(const char *str, char buffer[], size_t maxlength)

{

	size_t real_bytes = 0;

	size_t length = strlen(str);

	for (size_t i=0; i<length; i++)

	{

		if (real_bytes >= maxlength)

		{

			break;

		}

		buffer[real_bytes++] = (unsigned char)str[i];

		if (str[i] == '\\'

			&& str[i+1] == 'x')

		{

			if (i + 3 >= length)

			{

				continue;

			}

			/* Get the hex part */

			char s_byte[3];

			int r_byte;

			s_byte[0] = str[i+2];

			s_byte[1] = str[i+3];

			s_byte[2] = '\n';

			/* Read it as an integer */

			sscanf(s_byte, "%x", &r_byte);

			/* Save the value */

			buffer[real_bytes-1] = (unsigned char)r_byte;

			/* Adjust index */

			i += 3;

		}

	}

	return real_bytes;

}

bool UTIL_VerifySignature(const void *addr, const char *sig, size_t len)

{

	unsigned char *addr1 = (unsigned char *) addr;

	unsigned char *addr2 = (unsigned char *) sig;

	for (size_t i = 0; i < len; i++)

	{

		if (addr2[i] == '*')

			continue;

		if (addr1[i] != addr2[i])

			return false;

	}

	return true;

}

#if defined PLATFORM_WINDOWS

void GetIServer()

{

	const char *sigstr;

	char sig[32];

	size_t siglen;

	int offset;

	void *vfunc = NULL;

#if defined METAMOD_PLAPI_VERSION

	/* Get the CreateFakeClient function pointer */

	if (!(vfunc=SH_GET_ORIG_VFNPTR_ENTRY(engine, &IVEngineServer::CreateFakeClient)))

	{

		return;

	}

#else

	/* Get the interface manually */

	SourceHook::MemFuncInfo info = {true, -1, 0, 0};

	SourceHook::GetFuncInfo(&IVEngineServer::CreateFakeClient, info);

	vfunc = enginePatch->GetOrigFunc(info.vtbloffs, info.vtblindex);

	if (!vfunc)

	{

		void **vtable = *reinterpret_cast<void ***>(enginePatch->GetThisPtr() + info.thisptroffs + info.vtbloffs);

		vfunc = vtable[info.vtblindex];

	}

#endif

	/* Get signature string for IVEngineServer::CreateFakeClient() */

	sigstr = g_pGameConf->GetKeyValue("CreateFakeClient_Windows");

	if (!sigstr)

	{

		return;

	}

	/* Convert signature string to signature bytes */

	siglen = UTIL_StringToSignature(sigstr, sig, sizeof(sig));

	/* Check if we're on the expected function */

	if (!UTIL_VerifySignature(vfunc, sig, siglen))

	{

		return;

	}

	/* Get the offset into CreateFakeClient */

	if (!g_pGameConf->GetOffset("sv", &offset))

	{

		return;

	}

	/* Finally we have the interface we were looking for */

	iserver = *reinterpret_cast<IServer **>(reinterpret_cast<unsigned char *>(vfunc) + offset);

}

#elif defined PLATFORM_POSIX

void GetIServer()

{

	void *addr;

	if (!g_pGameConf->GetMemSig("sv", &addr) || !addr)

	{

		return;

	}

	iserver = reinterpret_cast<IServer *>(addr);

}

#endif