hook.cpp

#include "include/hook.h"

// credit goes to Trypthamine (https://github.com/NougatBitz/HookBasedInjection) for this
#define Offset(Base, Rva) reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(Base) + Rva)

__forceinline void* read_jmp_rel32(Process& p, void* instruction) {
    int32_t relativeoffset = 0;
    p.read_mem(Offset(instruction, 1), &relativeoffset, sizeof(int32_t), NULL);
    return Offset(Offset(instruction, 5), relativeoffset);
}

__forceinline void* read_jmp_m64(Process& p, void* instruction) {
    void* m64 = 0;
    p.read_mem(Offset(instruction, 6), &m64, sizeof(void*), NULL);
    return m64;
}

__forceinline void* write_jmp_m64(Process& p, void* instruction, void* target) {
    void* oldtarget = read_jmp_m64(p, instruction);
    DWORD oldprot;
    p.change_protection(Offset(instruction, 6), sizeof(void*), PAGE_EXECUTE_READWRITE, &oldprot);
    p.write_mem(Offset(instruction, 6), &target, sizeof(void*), NULL);
    p.change_protection(Offset(instruction, 6), sizeof(void*), oldprot, NULL);
    return oldtarget;
}

Hook::Hook(std::string name, void* address)
{
	this->currentFunction.name = name;
	this->currentFunction.address = address;
}

Hook::HookedFunction Hook::get_hooked_function()
{
    return this->currentFunction;
}

Hook::CurrentHook Hook::get_current_hook()
{
    return this->currentHook;
}

void Hook::hook_function(Process& p, void* jmpPage)
{
    auto dynamicstub = read_jmp_rel32(p, this->currentFunction.address);
    printf("[%s] Dynamic Stub Jmp Relative Offset = 0x%p\n", __FUNCTION__, dynamicstub);
    auto hook = read_jmp_m64(p, dynamicstub);
    printf("[%s] Hook Jmp m64 = 0x%p\n", __FUNCTION__, hook);
    write_jmp_m64(p, dynamicstub, jmpPage);
    this->currentHook.address = jmpPage;
    this->currentHook.previousaddress = hook;
    this->currentHook.stub = dynamicstub;
}

void Hook::unhook(Process& p)
{
    write_jmp_m64(p, this->currentHook.stub, this->currentHook.previousaddress);
    FlushInstructionCache(p.get_handle(), nullptr, 0);
}

Hook::~Hook()
{
}