/**

  * vim: set ts=4 sw=4 tw=99 noet :

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

  * SourceMod

  * Copyright (C) 2004-2009 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: $Id$

  */

 /**

  * On SourceHook v4.3 or lower, there are no DVP hooks. Very sad, right?

  * Only do this on newer version. For the older code, we'll do an incredibly

  * hacky detour.

  *

  * The idea of the "non-hacky" (yeah... no) code is that every unique

  * ConCommand vtable gets its own DVP hook. We watch for unloading and

  * loading commands to remove stale hooks from SH.

  */

 #include "sourcemod.h"

 #include "sourcemm_api.h"

 #include "Logger.h"

 #include "compat_wrappers.h"

 #include "ConsoleDetours.h"

 #include "GameConfigs.h"

 #include "sm_stringutil.h"

 #include "ConCmdManager.h"

 #include "HalfLife2.h"

 #include "ConCommandBaseIterator.h"

 #if defined PLATFORM_LINUX

 # include <dlfcn.h>

 # include <sys/mman.h>

 # include <stdint.h>

 # include <unistd.h>

 #endif

 #if SH_IMPL_VERSION >= 5

 # if SOURCE_ENGINE >= SE_ORANGEBOX

 	SH_DECL_EXTERN1_void(ConCommand, Dispatch, SH_NOATTRIB, false, const CCommand &);

 # else

 	SH_DECL_EXTERN0_void(ConCommand, Dispatch, SH_NOATTRIB, false);

 # endif

 #elif SH_IMPL_VERSION == 3

 extern bool __SourceHook_FHAddConCommandDispatch(void *, bool, class fastdelegate::FastDelegate0<void>);

 extern bool __SourceHook_FHRemoveConCommandDispatch(void *, bool, class fastdelegate::FastDelegate0<void>);

 #endif

 #if SH_IMPL_VERSION >= 4

 class GenericCommandHooker : public IConCommandLinkListener

 {

 	struct HackInfo

 	{

 		void **vtable;

 		int hook;

 		unsigned int refcount;

 	};

 	CVector<HackInfo> vtables;

 	bool enabled;

 	SourceHook::MemFuncInfo dispatch;

 	inline void **GetVirtualTable(ConCommandBase *pBase)

 	{

 		return *reinterpret_cast<void***>(reinterpret_cast<char*>(pBase) +

 		                                  dispatch.thisptroffs +

 		                                  dispatch.vtbloffs);

 	}

 	inline bool FindVtable(void **ptr, size_t& index)

 	{

 		for (size_t i = 0; i < vtables.size(); i++)

 		{

 			if (vtables[i].vtable == ptr)

 			{

 				index = i;

 				return true;

 			}

 		}

 		return false;

 	}

 	void MakeHookable(ConCommandBase *pBase)

 	{

 		if (!pBase->IsCommand())

 			return;

 		ConCommand *cmd = (ConCommand*)pBase;

 		void **vtable = GetVirtualTable(cmd);

 		size_t index;

 		if (!FindVtable(vtable, index))

 		{

 			HackInfo hack;

 			hack.vtable = vtable;

 			hack.hook = SH_ADD_VPHOOK(ConCommand, Dispatch, cmd, SH_MEMBER(this, &GenericCommandHooker::Dispatch), false);

 			hack.refcount = 1;

 			vtables.push_back(hack);

 		}

 		else

 		{

 			vtables[index].refcount++;

 		}

 	}

 # if SOURCE_ENGINE >= SE_ORANGEBOX

 	void Dispatch(const CCommand& args)

 # else

 	void Dispatch()

 # endif

 	{

 		cell_t res = ConsoleDetours::Dispatch(META_IFACEPTR(ConCommand)

 # if SOURCE_ENGINE >= SE_ORANGEBOX

 			, args

 # endif

 			);

 		if (res >= Pl_Handled)

 			RETURN_META(MRES_SUPERCEDE);

 	}

 	void ReparseCommandList()

 	{

 		for (size_t i = 0; i < vtables.size(); i++)

 			vtables[i].refcount = 0;

 		for (ConCommandBaseIterator iter; iter.IsValid(); iter.Next())

 			MakeHookable(iter.Get());

 		CVector<HackInfo>::iterator iter = vtables.begin();

 		while (iter != vtables.end())

 		{

 			if ((*iter).refcount)

 				continue;

 			/* Damn it. This event happens AFTER the plugin has unloaded!

 			 * There's two options. Remove the hook now and hope SH's memory

 			 * protection will prevent a crash. Otherwise, we can wait until

 			 * the server shuts down and more likely crash then.

 			 *

 			 * This situation only arises if:

 			 * 1) Someone has used AddCommandFilter()

 			 * 2) ... on a Dark Messiah server (mm:s new api)

 			 * 3) ... and another MM:S plugin that uses ConCommands has unloaded.

 			 *

 			 * Even though the impact is really small, we'll wait until the

 			 * server shuts down, so normal operation isn't interrupted.

 			 *

 			 * See bug 4018.

 			 */

 			iter = vtables.erase(iter);

 		}

 	}

 	void UnhookCommand(ConCommandBase *pBase)

 	{

 		if (!pBase->IsCommand())

 			return;

 		ConCommand *cmd = (ConCommand*)pBase;

 		void **vtable = GetVirtualTable(cmd);

 		size_t index;

 		if (!FindVtable(vtable, index))

 		{

 			g_Logger.LogError("Console detour tried to unhook command \"%s\" but it wasn't found", pBase->GetName());

 			return;

 		}

 		assert(vtables[index].refcount > 0);

 		vtables[index].refcount--;

 		if (vtables[index].refcount == 0)

 		{

 			SH_REMOVE_HOOK_ID(vtables[index].hook);

 			vtables.erase(vtables.iterAt(index));

 		}

 	}

 public:

 	GenericCommandHooker() : enabled(false)

 	{

 	}

 	bool Enable()

 	{

 		SourceHook::GetFuncInfo(&ConCommand::Dispatch, dispatch);

 		if (dispatch.thisptroffs < 0)

 		{

 			g_Logger.LogError("Command filter could not determine ConCommand layout");

 			return false;

 		}

 		for (ConCommandBaseIterator iter; iter.IsValid(); iter.Next())

 			MakeHookable(iter.Get());

 		if (!vtables.size())

 		{

 			g_Logger.LogError("Command filter could not find any cvars!");

 			return false;

 		}

 		enabled = true;

 		return true;

 	}

 	void Disable()

 	{

 		for (size_t i = 0; i < vtables.size(); i++)

 			SH_REMOVE_HOOK_ID(vtables[i].hook);

 		vtables.clear();

 	}

 	virtual void OnLinkConCommand(ConCommandBase *pBase)

 	{

 		if (!enabled)

 			return;

 		MakeHookable(pBase);

 	}

 	virtual void OnUnlinkConCommand(ConCommandBase *pBase)

 	{

 		if (!enabled)

 			return;

 		if (pBase == NULL)

 			ReparseCommandList();

 		else

 			UnhookCommand(pBase);

 	}

 };

 /**

  * END DVP HOOK VERSION

  */

 #else /* SH_IMPL_VERSION >= 4 */

 /**

  * BEGIN ENGINE DETOUR VERSION

  */

 # include <jit/jit_helpers.h>

 # include <jit/x86/x86_macros.h>

 class GenericCommandHooker

 {

 	struct Patch

 	{

 		Patch() : applied(false)

 		{

 		}

 		bool applied;

 		void *base;

 		unsigned char search[16];

 		size_t search_len;

 		size_t offset;

 		size_t saveat;

 		int regparam;

 		void *detour;

 	};

 	Patch ces;

 	Patch cgc;

 public:

 	bool Enable()

 	{

 		const char *platform = NULL;

 # if defined(PLATFORM_WINDOWS)

 		platform = "Windows";

 # else	

 		void *addrInBase = (void *)g_SMAPI->GetEngineFactory(false);

 		Dl_info info;

 		if (!dladdr(addrInBase, &info))

 		{

 			g_Logger.LogError("Command filter could not find engine name");

 			return false;

 		}

 		if (strstr(info.dli_fname, "engine_i486"))

 		{

 			platform = "Linux_486";

 		}

 		else if (strstr(info.dli_fname, "engine_i686"))

 		{

 			platform = "Linux_686";

 		}

 		else if (strstr(info.dli_fname, "engine_amd"))

 		{

 			platform = "Linux_AMD";

 		}

 		else

 		{

 			g_Logger.LogError("Command filter could not determine engine (%s)", info.dli_fname);

 			return false;

 		}

 # endif

 		if (!PrepPatch("Cmd_ExecuteString", "CES", platform, &ces))

 			return false;

 		if (!PrepPatch("CGameClient::ExecuteString", "CGC", platform, &cgc))

 			return false;

 		ApplyPatch(&ces);

 		ApplyPatch(&cgc);

 		return true;

 	}

 	void Disable()

 	{

 		UndoPatch(&ces);

 		UndoPatch(&cgc);

 	}

 private:

 # if !defined PLATFORM_WINDOWS

 #  define PAGE_READWRITE     PROT_READ|PROT_WRITE

 #  define PAGE_EXECUTE_READ  PROT_READ|PROT_EXEC

 	static inline uintptr_t AddrToPage(uintptr_t address)

 	{

 		return (address & ~(uintptr_t(sysconf(_SC_PAGE_SIZE) - 1)));

 	}

 # endif

 	void Protect(void *addr, size_t length, int prot)

 	{

 # if defined PLATFORM_WINDOWS

 		DWORD ignore;

 		VirtualProtect(addr, length, prot, &ignore);

 # else

 		uintptr_t startPage = AddrToPage(uintptr_t(addr));

 		length += (uintptr_t(addr) - startPage);

 		mprotect((void*)startPage, length, prot);

 # endif

 	}

 	void UndoPatch(Patch *patch)

 	{

 		if (!patch->applied || patch->detour == NULL)

 			return;

 		g_pSourcePawn->FreePageMemory(patch->detour);

 		unsigned char *source = (unsigned char *)patch->base + patch->offset;

 		Protect(source, patch->search_len, PAGE_READWRITE);

 		for (size_t i = 0; i < patch->search_len; i++)

 			source[i] = patch->search[i];

 		Protect(source, patch->search_len, PAGE_EXECUTE_READ);

 	}

 	void ApplyPatch(Patch *patch)

 	{

 		assert(!patch->applied);

 		size_t length = 0;

 		void *callback = (void*)&ConsoleDetours::Dispatch;

 		/* Bogus assignment to make compiler is doing the right thing. */

 		patch->detour = callback;

 		/* Assemgle the detour. */

 		JitWriter writer;

 		writer.outbase = NULL;

 		writer.outptr = NULL;

 		do

 		{

 			/* Need a specific register, or value on stack? */

 			if (patch->regparam != -1)

 				IA32_Push_Reg(&writer, patch->regparam);

 			/* Call real function. */

 			IA32_Write_Jump32_Abs(&writer, IA32_Call_Imm32(&writer, 0), callback);

 			/* Restore stack. */

 			if (patch->regparam != -1)

 				IA32_Pop_Reg(&writer, patch->regparam);

 			/* Copy any saved bytes */

 			if (patch->saveat)

 			{

 				for (size_t i = patch->saveat; i < patch->search_len; i++)

 				{

 					writer.write_ubyte(patch->search[i]);

 				}

 			}

 			/* Jump back to the caller. */

 			unsigned char *target = (unsigned char *)patch->base + patch->offset + patch->search_len;

 			IA32_Jump_Imm32_Abs(&writer, target);

 			/* Assemble, if we can. */

 			if (writer.outbase == NULL)

 			{

 				length = writer.outptr - writer.outbase;

 				patch->detour = g_pSourcePawn->AllocatePageMemory(length);

 				if (patch->detour == NULL)

 				{

 					g_Logger.LogError("Ran out of memory!");

 					return;

 				}

 				g_pSourcePawn->SetReadWrite(patch->detour);

 				writer.outbase = (jitcode_t)patch->detour;

 				writer.outptr = writer.outbase;

 			}

 			else

 			{

 				break;

 			}

 		} while (true);

 		g_pSourcePawn->SetReadExecute(patch->detour);

 		unsigned char *source = (unsigned char *)patch->base + patch->offset;

 		Protect(source, 6, PAGE_READWRITE);

 		source[0] = 0xFF;

 		source[1] = 0x25;

 		*(void **)&source[2] = &patch->detour;

 		Protect(source, 6, PAGE_EXECUTE_READ);

 		patch->applied = true;

 	}

 	bool PrepPatch(const char *signature, const char *name, const char *platform, Patch *patch)

 	{

 		/* Get the base address of the function. */

 		if (!g_pGameConf->GetMemSig(signature, &patch->base) || patch->base == NULL)

 		{

 			g_Logger.LogError("Command filter could not find signature: %s", signature);

 			return false;

 		}

 		const char *value;

 		char keyname[255];

 		/* Get the verification bytes that will be written over. */

 		UTIL_Format(keyname, sizeof(keyname), "%s_Patch_%s", name, platform);

 		if ((value = g_pGameConf->GetKeyValue(keyname)) == NULL)

 		{

 			g_Logger.LogError("Command filter could not find key: %s", keyname);

 			return false;

 		}

 		patch->search_len = UTIL_DecodeHexString(patch->search, sizeof(patch->search), value);

 		if (patch->search_len < 6)

 		{

 			g_Logger.LogError("Error decoding %s value, or not long enough", keyname);

 			return false;

 		}

 		/* Get the offset into the function. */

 		UTIL_Format(keyname, sizeof(keyname), "%s_Offset_%s", name, platform);

 		if ((value = g_pGameConf->GetKeyValue(keyname)) == NULL)

 		{

 			g_Logger.LogError("Command filter could not find key: %s", keyname);

 			return false;

 		}

 		patch->offset = atoi(value);

 		if (patch->offset > 20000)

 		{

 			g_Logger.LogError("Command filter %s value is bogus", keyname);

 			return false;

 		}

 		/* Get the number of bytes to save from what was written over. */

 		patch->saveat = 0;

 		UTIL_Format(keyname, sizeof(keyname), "%s_Save_%s", name, platform);

 		if ((value = g_pGameConf->GetKeyValue(keyname)) != NULL)

 		{

 			patch->saveat = atoi(value);

 			if (patch->saveat >= patch->search_len)

 			{

 				g_Logger.LogError("Command filter %s value is too large", keyname);

 				return false;

 			}

 		}

 		/* Get register for parameter, if any. */

 		patch->regparam = -1;

 		UTIL_Format(keyname, sizeof(keyname), "%s_Reg_%s", name, platform);

 		if ((value = g_pGameConf->GetKeyValue(keyname)) != NULL)

 		{

 			patch->regparam = atoi(value);

 		}

 		/* Everything loaded from gamedata, make sure the patch will succeed. */

 		unsigned char *address = (unsigned char *)patch->base + patch->offset;

 		for (size_t i = 0; i < patch->search_len; i++)

 		{

 			if (address[i] != patch->search[i])

 			{

 				g_Logger.LogError("Command filter %s has changed (byte %x is not %x sub-offset %d)",

 				                  name, address[i], patch->search[i], i);

 				return false;

 			}

 		}

 		return true;

 	}

 };

 static bool dummy_hook_set = false;

 void DummyHook()

 {

 	if (dummy_hook_set)

 	{

 		dummy_hook_set = false;

 		RETURN_META(MRES_SUPERCEDE);

 	}

 }

 #endif

 /**

  * BEGIN THE ACTUALLY GENERIC CODE.

  */

 static GenericCommandHooker s_GenericHooker;

 ConsoleDetours g_ConsoleDetours;

 ConsoleDetours::ConsoleDetours() : triedToEnable(false), isEnabled(false)

 {

 }

 void ConsoleDetours::OnSourceModAllInitialized()

 {

 	m_pForward = g_Forwards.CreateForwardEx("OnAnyCommand", ET_Hook, 3, NULL, Param_Cell,

 	                                        Param_String, Param_Cell);

 }

 void ConsoleDetours::OnSourceModShutdown()

 {

 	List<Listener*>::iterator iter = m_Listeners.begin();

 	while (iter != m_Listeners.end())

 	{

 		Listener *listener = (*iter);

 		g_Forwards.ReleaseForward(listener->forward);

 		delete listener;

 		iter = m_Listeners.erase(iter);

 	}

 	g_Forwards.ReleaseForward(m_pForward);

 	s_GenericHooker.Disable();

 }

 bool ConsoleDetours::IsAvailable()

 {

 	if (triedToEnable)

 		return isEnabled;

 	isEnabled = s_GenericHooker.Enable();

 	triedToEnable = true;

 	return isEnabled;

 }

 bool ConsoleDetours::AddListener(IPluginFunction *fun, const char *command)

 {

 	if (!IsAvailable())

 		return false;

 	if (command == NULL)

 	{

 		m_pForward->AddFunction(fun);

 	}

 	else

 	{

 		const char *str = UTIL_ToLowerCase(command);

 		Listener *listener;

 		Listener **plistener = m_CmdLookup.retrieve(str);

 		if (plistener == NULL)

 		{

 			listener = new Listener;

 			listener->forward = g_Forwards.CreateForwardEx(NULL, ET_Hook, 3, NULL, Param_Cell,

 			                                               Param_String, Param_Cell);

 			m_CmdLookup.insert(str, listener);

 		}

 		else

 		{

 			listener = *plistener;

 		}

 		listener->forward->AddFunction(fun);

 		delete [] str;

 	}

 	return true;

 }

 bool ConsoleDetours::RemoveListener(IPluginFunction *fun, const char *command)

 {

 	if (command == NULL)

 	{

 		return m_pForward->RemoveFunction(fun);

 	}

 	else

 	{

 		const char *str = UTIL_ToLowerCase(command);

 		Listener *listener;

 		Listener **plistener = m_CmdLookup.retrieve(str);

 		delete [] str;

 		if (plistener == NULL)

 			return false;

 		listener = *plistener;

 		return listener->forward->RemoveFunction(fun);

 	}

 }

 cell_t ConsoleDetours::InternalDispatch(int client, const CCommand& args)

 {

 	char name[255];

 	const char *realname = args.Arg(0);

 	size_t len = strlen(realname);

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

 	{

 		if (realname[i] >= 'A' && realname[i] <= 'Z')

 			name[i] = tolower(realname[i]);

 		else

 			name[i] = realname[i];

 	}

 	name[len] = '\0';

 	cell_t result = Pl_Continue;

 	m_pForward->PushCell(client);

 	m_pForward->PushString(name);

 	m_pForward->PushCell(args.ArgC() - 1);

 	m_pForward->Execute(&result, NULL);

 	/* Don't let plugins block this. */

 	if (strcmp(name, "sm") == 0)

 		result = Pl_Continue;

 	if (result >= Pl_Stop)

 		return result;

 	Listener **plistener = m_CmdLookup.retrieve(name);

 	if (plistener == NULL)

 		return result;

 	Listener *listener = *plistener;

 	if (listener->forward->GetFunctionCount() == 0)

 		return result;

 	cell_t result2 = Pl_Continue;

 	listener->forward->PushCell(client);

 	listener->forward->PushString(name);

 	listener->forward->PushCell(args.ArgC() - 1);

 	listener->forward->Execute(&result2, NULL);

 	if (result2 > result)

 		result = result2;

 	/* "sm" should not have flown through the above. */

 	assert(strcmp(name, "sm") != 0 || result == Pl_Continue);

 	return result;

 }

 #if SOURCE_ENGINE >= SE_ORANGEBOX

 cell_t ConsoleDetours::Dispatch(ConCommand *pBase, const CCommand& args)

 {

 #else

 cell_t ConsoleDetours::Dispatch(ConCommand *pBase)

 {

 	CCommand args;

 #endif

 	g_HL2.PushCommandStack(&args);

 	cell_t res = g_ConsoleDetours.InternalDispatch(g_ConCmds.GetCommandClient(), args);

 	g_HL2.PopCommandStack();

 #if SH_IMPL_VERSION < 4

 	if (res >= Pl_Handled)

 	{

 		/* See bug 4020 - we can't optimize this because looking at the vtable

 		 * is probably more expensive, since there's no SH_GET_ORIG_VFNPTR_ENTRY.

 		 */

 		SH_ADD_HOOK_STATICFUNC(ConCommand, Dispatch, pBase, DummyHook, false);

 		dummy_hook_set = true;

 		pBase->Dispatch();

 		SH_REMOVE_HOOK_STATICFUNC(ConCommand, Dispatch, pBase, DummyHook, false);

 	}

 	else

 	{

 		/* Make sure the command gets invoked. See bug 4019 on making this better. */

 		pBase->Dispatch();

 	}

 #endif

 	return res;

 }