/**

 * 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);