/**
* Simple Memory Scanner Example
* (c) 2014 atom0s [atom0s@live.com]
*/

#include <Windows.h>
#include <string>
#include <TlHelp32.h>
#include <tchar.h>
//#include "stdafx.h"

/**
* @brief The target process to scan within.
*/
#define TARGET_NAME TEXT("Tutorial-i386.exe")

/**
* @brief Obtains the process id of the given target.
*
* @return The process id if found, 0 otherwise.
*/
unsigned int getTargetProcessId()
{
    PROCESSENTRY32 pe32 = { sizeof(PROCESSENTRY32) };

    // Obtain a snapshot of the current process list..
    auto handle = ::CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
    if (handle == INVALID_HANDLE_VALUE)
        return 0;

    // Obtain the first process..
    if (!::Process32First(handle, &pe32))
    {
        ::CloseHandle(handle);
        return 0;
    }

    // Loop each process looking for the target..
    do
    {
        if (!_tcsicmp(pe32.szExeFile, TARGET_NAME))
        {
            ::CloseHandle(handle);
            return pe32.th32ProcessID;
        }
    } while (::Process32Next(handle, &pe32));

    // Cleanup..
    ::CloseHandle(handle);
    return 0;
}

/**
* @brief Entry point of this application.
*
* @param argc  The count of arguments passed to this application.
* @param argv  The array of arguments passed to this application.
*
* @return Non-important return.
*/
int __cdecl main(int argc, char* argv[])
{
    // Obtain the target process id..
    auto processId = getTargetProcessId();
    if (processId == 0)
        return 0;

    // Open a handle to the target..
    auto handle = ::OpenProcess(PROCESS_VM_OPERATION | PROCESS_VM_READ | PROCESS_VM_WRITE | PROCESS_QUERY_INFORMATION, FALSE, processId);
    if (handle == INVALID_HANDLE_VALUE)
        return 0;

    // Obtain the current system information..
    SYSTEM_INFO sysInfo;
    ::GetSystemInfo(&sysInfo);

    auto addr_min = (intptr_t)sysInfo.lpMinimumApplicationAddress;
    auto addr_max = (intptr_t)sysInfo.lpMaximumApplicationAddress;

    auto found = 0;

    // Loop the pages of memory of the application..
#define TARGET_SCAN_TYPE_INT 1
#define TARGET_SCAN_TYPE_8BYTE 2
#define TARGET_SCAN_TYPE_FLOAT 3
#define TARGET_SCAN_TYPE_DOUBLE 4

#define TARGET_SCAN_TYPE TARGET_SCAN_TYPE_8BYTE

#if TARGET_SCAN_TYPE == TARGET_SCAN_TYPE_INT
    typedef int32_t target_t;
    double TARGET_EPSILON = 0;
#define PRITARGET PRII32
#elif TARGET_SCAN_TYPE == TARGET_SCAN_TYPE_8BYTE
    typedef int64_t target_t;
    double TARGET_EPSILON = 0;
#define PRITARGET "%lli"
#elif TARGET_SCAN_TYPE == TARGET_SCAN_TYPE_FLOAT
    typedef float target_t;
    double TARGET_EPSILON = std::numeric_limits<float>::epsilon();
#define PRITARGET "%f"
#elif TARGET_SCAN_TYPE == TARGET_SCAN_TYPE_DOUBLE
    typedef double target_t;
    double TARGET_EPSILON = std::numeric_limits<double>::epsilon();
#define PRITARGET "%f"
#endif
    target_t targtValue = (target_t)13371337.0f;
    target_t targtWriteValue = (target_t)-13371337.0f;
    while (addr_min < addr_max)
    {
        MEMORY_BASIC_INFORMATION mbi = { 0 };
        if (!::VirtualQueryEx(handle, (LPCVOID)addr_min, &mbi, sizeof(mbi)))
        {
            printf_s("Failed to query memory.\n");
            break;
        }

        // Determine if we have access to the page..
        if (mbi.State == MEM_COMMIT && ((mbi.Protect & PAGE_GUARD) == 0) && ((mbi.Protect & PAGE_NOACCESS) == 0))
        {
            //
            // Below are flags about the current region of memory. If you want to specifically scan for only
            // certain things like if the area is writable, executable, etc. you can use these flags to prevent
            // reading non-desired protection types.
            //

            auto isCopyOnWrite = ((mbi.Protect & PAGE_WRITECOPY) != 0 || (mbi.Protect & PAGE_EXECUTE_WRITECOPY) != 0);
            auto isExecutable = ((mbi.Protect & PAGE_EXECUTE) != 0 || (mbi.Protect & PAGE_EXECUTE_READ) != 0 || (mbi.Protect & PAGE_EXECUTE_READWRITE) != 0 || (mbi.Protect & PAGE_EXECUTE_WRITECOPY) != 0);
            auto isWritable = ((mbi.Protect & PAGE_READWRITE) != 0 || (mbi.Protect & PAGE_WRITECOPY) != 0 || (mbi.Protect & PAGE_EXECUTE_READWRITE) != 0 || (mbi.Protect & PAGE_EXECUTE_WRITECOPY) != 0);

            // Dump the region into a memory block..
            auto dump = new uint8_t[mbi.RegionSize + 1];
            //memset(dump, 0x00, mbi.RegionSize + 1);
            if (!::ReadProcessMemory(handle, mbi.BaseAddress, dump, mbi.RegionSize, NULL))
            {
                printf_s("Failed to read memory of location: %p\n", mbi.BaseAddress);
                break;
            }

            for (size_t x = 0; x < mbi.RegionSize - 4; x += 4)
            {
                target_t value = *(target_t*)(dump + x);
                if (abs(value-targtValue) <= TARGET_EPSILON)
                {
                    found++;
                    // assuming unqiue value for testing
                    SIZE_T written;
                    BOOL success = WriteProcessMemory(handle, (void*)(addr_min + x), &targtWriteValue, sizeof(targtWriteValue), &written);
                    printf_s("%s in trying to write %zu bytes (" PRITARGET ") written to %p\n",
                        success ? "Succeded" : "Failed", written, targtWriteValue, (void*)(addr_min + x));
                }
            }

            // Cleanup the memory dump..
            delete[] dump;
        }

        // Step the current address by this regions size..
        addr_min += mbi.RegionSize;
    }

    printf_s("Found %d results!\n", found);

    // Cleanup..
    ::CloseHandle(handle);
    return ERROR_SUCCESS;
}