/*
 *  KernelEx
 *  Copyright (C) 2010, Xeno86
 *
 *  This file is part of KernelEx source code.
 *
 *  KernelEx is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published
 *  by the Free Software Foundation; version 2 of the License.
 *
 *  KernelEx 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 GNU Make; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <windows.h>
#include <cassert>
#include "patch.h"
#include "debug.h"
#include "loadstub.h"
#include "pemanip.h"
#include "resource.h"

#define CODE_SEG ".text"
#define DATA_SEG ".data"
#define INIT_SEG "_INIT"

void ShowError(UINT id, ...);


Patch::Patch(PEmanip& pem) : pefile(pem)
{
}

void Patch::apply()
{
	find_ExportFromX();
	find_IsKnownDLL();
	find_FLoadTreeNotify1();
	find_FLoadTreeNotify2();
	prepare_subsystem_check();
	find_resource_check1();
	find_resource_check2();
	disable_named_and_rcdata_resources_mirroring();
	mod_imte_alloc();
	mod_mr_alloc();
	mod_pdb_alloc();

	KernelEx_codeseg* cseg;
	KernelEx_dataseg* dseg;
	if (!pefile.AllocSectionSpace(CODE_SEG, 
			sizeof(KernelEx_codeseg), (void**) &cseg, sizeof(DWORD)))
		ShowError(IDS_FAILSEC, CODE_SEG);
	if (!pefile.AllocSectionSpace(DATA_SEG,
			sizeof(KernelEx_dataseg), (void**) &dseg, sizeof(DWORD)))
		ShowError(IDS_FAILSEC, DATA_SEG);

	memcpy(cseg->signature, "KrnlEx", 6);
	cseg->version = KEX_STUB_VER;
	for (int i = 0 ; i < JTAB_SIZE ; i++)
	{
		cseg->jmp_stub[i].opcode = 0x25ff;
		cseg->jmp_stub[i].addr = (DWORD) 
				pefile.PointerToRva(&dseg->jtab[i]) + pefile.GetImageBase();
		cseg->jmp_stub[i].nop = 0x9090;
	}

	memcpy(dseg->signature, "KrnlEx", 6);
	dseg->version = KEX_STUB_VER;
	dseg->jtab[JTAB_EFO_DYN] = _ExportFromOrdinal + pefile.GetImageBase();
	dseg->jtab[JTAB_EFO_STA] = _ExportFromOrdinal + pefile.GetImageBase();
	dseg->jtab[JTAB_EFN_DYN] = _ExportFromName + pefile.GetImageBase();
	dseg->jtab[JTAB_EFN_STA] = _ExportFromName + pefile.GetImageBase();
	dseg->jtab[JTAB_KNO_DLL] = _IsKnownDLL + pefile.GetImageBase();
	dseg->jtab[JTAB_FLD_TRN] = _FLoadTreeNotify + pefile.GetImageBase();
	dseg->jtab[JTAB_SYS_CHK] = _SubsysCheckPerform + pefile.GetImageBase();
	dseg->jtab[JTAB_RES_CHK] = _GetOrdinal + pefile.GetImageBase();

	//exportfromx patch
	DWORD code = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int code_size = pefile.GetSectionSize(CODE_SEG);

	int efo_cnt = 0;
	int efn_cnt = 0;

	for (DWORD a = code ; a < code + code_size ; a++)
	{
		if (is_call_ref(a, _ExportFromOrdinal))
		{
			DWORD file_loc = a;
			if (a == EFN_EFO_call) 
				continue;
			if (a == gpa_ExportFromOrdinal_call)
				set_call_ref(file_loc, (DWORD) &cseg->jmp_stub[JTAB_EFO_DYN]);
			else
				set_call_ref(file_loc, (DWORD) &cseg->jmp_stub[JTAB_EFO_STA]);
			DBGPRINTF(("%s: address 0x%08x\n", "EFO", pefile.PointerToRva((void*) a) 
					+ pefile.GetImageBase()));
			efo_cnt++;
		}
		else if (is_call_ref(a, _ExportFromName))
		{
			DWORD file_loc = a;
			if (is_fixupc(a))
				continue;
			if (a == gpa_ExportFromName_call)
				set_call_ref(file_loc, (DWORD) &cseg->jmp_stub[JTAB_EFN_DYN]);
			else
				set_call_ref(file_loc, (DWORD) &cseg->jmp_stub[JTAB_EFN_STA]);
			DBGPRINTF(("%s: address 0x%08x\n", "EFN", pefile.PointerToRva((void*) a) 
					+ pefile.GetImageBase()));
			efn_cnt++;
		}
	}

	if (efo_cnt != 2 || efn_cnt != 2)
		ShowError(IDS_ERRCHECK);

	//isknowndll patch
	set_call_ref(IsKnownDLL_call, (DWORD) &cseg->jmp_stub[JTAB_KNO_DLL]);
	DBGPRINTF(("%s: address 0x%08x\n", "KNO_DLL", pefile.PointerToRva((void*) IsKnownDLL_call) 
			+ pefile.GetImageBase()));

	//FLoadTreeNotify patch
	set_call_ref(FLoadTreeNotify_call1, (DWORD) &cseg->jmp_stub[JTAB_FLD_TRN]);
	DBGPRINTF(("%s: address 0x%08x\n", "FLD_TRN1", pefile.PointerToRva((void*) FLoadTreeNotify_call1)
			+ pefile.GetImageBase()));
	set_call_ref(FLoadTreeNotify_call2, (DWORD) &cseg->jmp_stub[JTAB_FLD_TRN]);
	DBGPRINTF(("%s: address 0x%08x\n", "FLD_TRN2", pefile.PointerToRva((void*) FLoadTreeNotify_call2)
			+ pefile.GetImageBase()));

	//subsys check patch
	set_jmp_ref(SubsysCheck_jmp, (DWORD) &cseg->jmp_stub[JTAB_SYS_CHK]);
	DBGPRINTF(("%s: address 0x%08x\n", "SYS_CHK", pefile.PointerToRva((void*) SubsysCheck_jmp)
			+ pefile.GetImageBase()));

	//resource check patch
	set_call_ref(GetOrdinal_call1, (DWORD) &cseg->jmp_stub[JTAB_RES_CHK]);
	DBGPRINTF(("%s: address 0x%08x\n", "RES_CHK1", pefile.PointerToRva((void*) GetOrdinal_call1)
			+ pefile.GetImageBase()));
	set_call_ref(GetOrdinal_call2, (DWORD) &cseg->jmp_stub[JTAB_RES_CHK]);
	DBGPRINTF(("%s: address 0x%08x\n", "RES_CHK2", pefile.PointerToRva((void*) GetOrdinal_call2)
			+ pefile.GetImageBase()));
}

int Patch::find_pattern(DWORD offset, int size, const short* pattern, 
						int pat_len, DWORD* found_loc)
{
	DWORD end_offset = offset + size - pat_len;
	int found = 0;

	for (DWORD i = offset ; i <= end_offset ; i++)
	{
		if (pattern[0] < 0 || *(unsigned char*)i == pattern[0])
		{
			int j;
			for (j = 1 ; j < pat_len ; j++)
			{
				if (pattern[j] >= 0 && *(unsigned char*)(i + j) != pattern[j]) 
					break;
			}
			if (j == pat_len) //pattern found
			{
				*found_loc = i;
				found++;
			}
		}
	}
	return found;
}

void Patch::set_pattern(DWORD loc, const short* new_pattern, int pat_len)
{
	unsigned char* offset = (unsigned char*) loc;
	const short* pat_ptr = new_pattern;

	while (pat_len--)
	{
		if (*pat_ptr != -1)
			*offset = *pat_ptr & 0xff;
		offset++;
		pat_ptr++;
	}
}

void Patch::prepare_subsystem_check()
{
	static const short pattern[] = {
		0x66,0x8b,0x46,0x48,0x66,0x3d,0x04,0x00,0x0f,0x87,0x9c,0x01,0x00,0x00,
		0x75,0x0b,0x66,0x83,0x7e,0x4a,0x0a,0x0f,0x87,0x8f,0x01,0x00,0x00,0x66,
		0x81,0x7e,0x04,0x4c,0x01,
	};
	static const short after[] = {
		0x66,0x83,0x7E,0x48,0x04,0x75,0x05,0x66,0x83,0x7E,0x4A,0x0A,0xE9,0x00,
		0x00,0x00,0x00,0x0F,0x87,0x93,0x01,0x00,0x00,0x90,0x90,0x90,0x90,0x66,
		0x81,0x7e,0x04,0x4c,0x01,
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size, pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "subsystem_check");
		else ShowError(IDS_MULPAT, "subsystem_check");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "subsystem_check", 
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	set_pattern(found_loc, after, length);
	
	SubsysCheck_jmp = found_loc + 12;
	_SubsysCheckPerform = decode_jmp(SubsysCheck_jmp, 5);
}

void Patch::find_resource_check1()
{
	static const short pattern[] = {
		0x6A,0x00,0x8D,0x45,0xE0,0x50,0xFF,0x75,0xA4,0xFF,0x75,0xD0,0x8D,0x45,
		0xCC,0x50,0xFF,0x75,0x08,0xE8,-2,-2,-2,-2,0x85,0xC0
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size,pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "resource_check1");
		else ShowError(IDS_MULPAT, "resource_check1");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "resource_check1", 
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	GetOrdinal_call1 = found_loc + 19;
	_GetOrdinal = decode_call(GetOrdinal_call1, 5);
}

void Patch::find_resource_check2()
{
	static const short pattern[] = {
		0x66,0x8B,0x45,0xE0,0x66,0x2D,0x06,0x80,0x66,0x3D,0x01,0x00,0x1B,0xC0,
		0xF7,0xD8,0x50,0x8D,0x45,0xDE,0x50,0xFF,0x75,  -1,0xFF,0x75,0xD0,0x8D,
		0x45,0xCC,0x50,0xFF,0x75,0x08,0xE8,  -2,  -2,  -2,  -2,0x85,0xC0
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size,pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "resource_check2");
		else ShowError(IDS_MULPAT, "resource_check2");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "resource_check2", 
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	GetOrdinal_call2 = found_loc + 34;
}

//no named/rcdata resource types mirroring
void Patch::disable_named_and_rcdata_resources_mirroring()
{
	static const short pattern[] = {
		0x66,0x8B,0x40,0x0E,0x66,0x89,0x45,0xDA,0x8B,0x45,  -1,0x66,0x8B,0x48,
		0x0C,0x66,0x89,0x4D,0xD8,0x66,0x8B,0x45,0xE0,0x8B,0x4D,0xD4,0x66,0x89,
		0x01,0x83,0x45,0xD4,0x02,0x66,0x8B,0x45,0xDA,0x66,0x03,0x45,0xD8,0x66,
		0x89,0x45,0x8C,0x8B,0x4D,0xD4,0x66,0x89,0x01,0x83,0x45,0xD4,0x02
	};
	static const short after[] = {
		0x66,0x8B,0x48,0x0E,0x66,0x03,0x48,0x0C,0x66,0x89,0x4D,0x8C,0x8B,0x45,
		0xA4,0x83,0x38,0x0A,0x74,0x40,0x83,0x38,0x00,0x79,0x04,0x3B,0xC0,0xEB,
		0x37,0x66,0x8B,0x45,0xE0,0x8B,0x4D,0xD4,0x66,0x89,0x01,0x83,0xC1,0x02,
		0x66,0x8B,0x45,0x8C,0x66,0x89,0x01,0x83,0xC1,0x02,0x89,0x4D,0xD4
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size, pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "disable_named_and_rcdata_resources_mirroring");
		else ShowError(IDS_MULPAT, "disable_named_and_rcdata_resources_mirroring");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "disable_named_and_rcdata_resources_mirroring",
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	set_pattern(found_loc, after, length);
}

void Patch::mod_imte_alloc()
{
	//VA BFF8745C, RVA 1745C, file 15A5C, sec E45C
	static const short pattern[] = {
		0x66,0xff,0x05,-1,-1,-1,0xbf,0x6a,0x3c,0xe8,
	};
	static const short after[] = {
		0x66,0xff,0x05,-1,-1,-1,0xbf,0x6a,0x40,0xe8,
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size, pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "mod_imte_alloc");
		else ShowError(IDS_MULPAT, "mod_imte_alloc");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "mod_imte_alloc",
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	set_pattern(found_loc, after, length);
}

void Patch::mod_mr_alloc()
{
	static const short pattern[] = {
		0x75,0xF6,0x8D,0x04,-1,0x1C,0x00,0x00,0x00,0x50
	};
	static const short after[] = {
		0x75,0xF6,0x8D,0x04,-1,0x24,0x00,0x00,0x00,0x50
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size, pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "mod_mr_alloc");
		else ShowError(IDS_MULPAT, "mod_mr_alloc");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "mod_mr_alloc",
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	set_pattern(found_loc, after, length);
}

void Patch::mod_pdb_alloc()
{
	static const short pattern[] = {
		0x53,0x56,0x57,0x6A,0x06,0x68,0xC4,0x00,0x00,0x00,0xE8
	};
	static const short after[] = {
		0x53,0x56,0x57,0x6A,0x06,0x68,0xC8,0x00,0x00,0x00,0xE8
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size, pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "mod_pdb_alloc");
		else ShowError(IDS_MULPAT, "mod_pdb_alloc");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "mod_pdb_alloc",
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	set_pattern(found_loc, after, length);
}

void Patch::find_ExportFromX()
{
	static const short pattern[] = {
		0x8B,0x0D,-1,-1,-1,-1,0x0F,0xBF,0x40,0x10,0x8B,0x14,0x81,0x8B,0x44,
		0x24,0x14,0x3D,0x00,0x00,0x01,0x00,0x8B,0x4A,0x04,0x73,0x15,-1,0x1D,
		-1,-1,-1,-1,0x75,0x04,0x6A,0x32,0xEB,0x3E,0x50,0x51,0xE8,-2,-2,-2,-2,
		0xEB,0x0C,0xFF,0x74,0x24,0x14,0x6A,0x00,0x51,0xE8,-2,-2,-2,-2,0x83,
		0x7F,0x54,0x00,0x8B,0xF0
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size,pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "exportfromX");
		else ShowError(IDS_MULPAT, "exportfromX");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "exportfromX", 
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	gpa_ExportFromOrdinal_call = found_loc + 0x29;
	gpa_ExportFromName_call = found_loc + 0x37;
	_ExportFromOrdinal = decode_call(gpa_ExportFromOrdinal_call, 5);
	_ExportFromName = decode_call(gpa_ExportFromName_call, 5);
	DWORD start = (DWORD) pefile.RvaToPointer(_ExportFromName);
	for (DWORD a = start ; a < start + 0x100 ; a++)
		if (is_call_ref(a, _ExportFromOrdinal))
			EFN_EFO_call = a;
}

void Patch::find_IsKnownDLL()
{
	static const short pattern[] = {
		0xFF,0x75,0xFC,0x8D,0x8D,0xF0,0xFE,0xFF,0xFF,0x51,0xE8,-2,-2,-2,-2,
		0x85,0xC0,0x75,0x1E,0x8D,0x85,0xE8,0xFD,0xFF,0xFF,
		0x8D,0x8D,0xF0,0xFE,0xFF,0xFF,0x50,0x51
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size,pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "IsKnownDLL");
		else ShowError(IDS_MULPAT, "IsKnownDLL");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "IsKnownDLL", 
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	IsKnownDLL_call = found_loc + 10;
	_IsKnownDLL = decode_call(IsKnownDLL_call, 5);
}

void Patch::find_FLoadTreeNotify1()
{
	static const short pattern[] = {
		0x56,0xA1,-1,-1,-1,-1,0x6A,0x01,0x8B,0x08,0xFF,0xB1,0x98,0x00,0x00,
		0x00,0xE8,-2,-2,-2,-2,0x83,0xF8,0x01,0x1B,0xF6,0xF7,0xDE
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size,pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "FLoadTreeNotify1");
		else ShowError(IDS_MULPAT, "FLoadTreeNotify1");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "FLoadTreeNotify1", 
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	FLoadTreeNotify_call1 = found_loc + 16;
	_FLoadTreeNotify = decode_call(FLoadTreeNotify_call1, 5);
}

void Patch::find_FLoadTreeNotify2()
{
	static const short pattern[] = {
		0x6A,0x00,0x57,0xE8,-1,-1,-1,-1,0x6A,0x00,0x56,0xE8,-2,-2,-2,-2,
		0x85,0xC0,0x74,0x12,0x56,0xE8,-1,-1,-1,-1,0x68,0x5A,0x04,0x00,0x00,
		0x33,0xF6,0xE8,-1,-1,-1,-1
	};

	DWORD offset = (DWORD) pefile.GetSectionByName(CODE_SEG);
	int size = pefile.GetSectionSize(CODE_SEG);
	int length = sizeof(pattern) / sizeof(short);
	DWORD found_loc;
	int found = find_pattern(offset, size,pattern, length, &found_loc);
	if (found != 1)
	{
		if (!found) ShowError(IDS_NOPAT, "FLoadTreeNotify2");
		else ShowError(IDS_MULPAT, "FLoadTreeNotify2");
	}
	DBGPRINTF(("%s: pattern found @ 0x%08x\n", "FLoadTreeNotify2", 
			pefile.PointerToRva((void*) found_loc) + pefile.GetImageBase()));
	FLoadTreeNotify_call2 = found_loc + 11;
}

DWORD Patch::decode_call(DWORD addr, int len)
{
	unsigned char* code = (unsigned char*)addr;

	/* CALL rel32 */
	if (code[0] == 0xe8)
	{
		if (len && len == 5 || !len)
		return (DWORD)(pefile.PointerToRva(code) + 5 + *(INT32*)(code + 1));
	}
	/* CALL imm32 */
	else if (code[0] == 0xff && code[1] == 0x15)
	{
		if (len && len == 6 || !len)
		return *(DWORD*)(code + 2);
	}
	/* unmatched */
	return 0;
}

DWORD Patch::decode_jmp(DWORD addr, int len)
{
	unsigned char* code = (unsigned char*)addr;

	/* JMP rel8 */
	if (code[0] == 0xeb)
	{
		if (len && len == 2 || !len)
		return (DWORD)(pefile.PointerToRva(code) + 2 + *(INT8*)(code + 1));
	}
	/* JMP rel32 */
	else if (code[0] == 0xe9)
	{
		if (len && len == 5 || !len)
		return (DWORD)(pefile.PointerToRva(code) + 5 + *(INT32*)(code + 1));
	}
	/* JMP imm32 */
	else if (code[0] == 0xff && code[1] == 0x25)
	{
		if (len && len == 6 || !len)
		return *(DWORD*)(code + 2);
	}
	/* Jxx rel8 */
	else if (code[0] >= 0x70 && code[0] < 0x7f || code[0] == 0xe3)
	{
		if (len && len == 2 || !len)
		return (DWORD)(pefile.PointerToRva(code) + 2 + *(INT8*)(code + 1));
	}
	/* Jxx rel32 */
	else if (code[0] == 0x0f && code[1] >= 0x80 && code[1] <= 0x8f)
	{
		if (len && len == 6 || !len)
		return (DWORD)(pefile.PointerToRva(code) + 6 + *(INT32*)(code + 2));
	}
	/* unmatched */
	return 0;
}

bool Patch::is_call_ref(DWORD loc, DWORD target)
{
	DWORD addr = decode_call(loc, 5); // size of call imm32 opcode
	if (addr == target)
		return true;
	return false;
}

// Both addresses have to be from the same section!
void Patch::set_call_ref(DWORD loc, DWORD target)
{
	DWORD rel;

	assert(*(BYTE*) loc == 0xe8);

	rel = target - (loc + 5);
	*(DWORD*)(loc + 1) = rel;
}

// Both addresses have to be from the same section!
void Patch::set_jmp_ref(DWORD loc, DWORD target)
{
	DWORD rel;
	unsigned char* code = (unsigned char*)loc;

	if (code[0] == 0xe9)
	{
		rel = target - (loc + 5);
		*(DWORD*)(loc + 1) = rel;
	}
	else if (code[0] == 0x0f && code[1] >= 0x80 && code[1] <= 0x8f)
	{
		rel = target - (loc + 6);
		*(DWORD*)(loc + 2) = rel;
	}
	else assert(false);
}

bool Patch::is_fixupc(DWORD addr)
{
	if (*(DWORD*)(addr - 5) == 0xDAC)
		return true;
	return false;
}