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libhat

A modern, high-performance library for C++20 designed around game hacking

Feature overview

  • Windows x86/x64 support
  • Vectorized scanning for byte patterns
  • RAII memory protector
  • Convenience wrappers over OS APIs
  • Language bindings (C, C#, etc.)

Versioning

This project adheres to semantic versioning. Any declaration that is within a detail or experimental namespace is not considered part of the public API, and usage may break at any time without the MAJOR version number being incremented.

Benchmarks

The table below compares the single threaded throughput in bytes/s (real time) between libhat and two other commonly used implementations for pattern scanning. The input buffers were randomly generated using a fixed seed, and the pattern scanned does not contain any match in the buffer. The benchmark was run on a system with an i7-9700K (which supports libhat's AVX2 scanner implementation). The full source code is available here.

---------------------------------------------------------------------------------------
Benchmark                            Time             CPU   Iterations bytes_per_second
---------------------------------------------------------------------------------------
BM_Throughput_Libhat/4MiB       131578 ns        48967 ns        21379      29.6876Gi/s
BM_Throughput_Libhat/16MiB      813977 ns       413524 ns         3514      19.1959Gi/s
BM_Throughput_Libhat/128MiB    6910936 ns      3993486 ns          403      18.0873Gi/s
BM_Throughput_Libhat/256MiB   13959379 ns      8121906 ns          202      17.9091Gi/s

BM_Throughput_UC1/4MiB         4739731 ns      2776015 ns          591       843.93Mi/s
BM_Throughput_UC1/16MiB       19011485 ns     10841837 ns          147      841.597Mi/s
BM_Throughput_UC1/128MiB     152277511 ns     82465278 ns           18      840.571Mi/s
BM_Throughput_UC1/256MiB     304964544 ns    180555556 ns            9      839.442Mi/s

BM_Throughput_UC2/4MiB         9633499 ns      4617698 ns          291      415.218Mi/s
BM_Throughput_UC2/16MiB       38507193 ns     22474315 ns           73      415.507Mi/s
BM_Throughput_UC2/128MiB     307989100 ns    164930556 ns            9      415.599Mi/s
BM_Throughput_UC2/256MiB     616449240 ns    331250000 ns            5      415.282Mi/s

Quick start

Pattern scanning

#include <libhat/Scanner.hpp>

// Parse a pattern's string representation to an array of bytes at compile time
constexpr hat::fixed_signature pattern = hat::compile_signature<"48 8D 05 ? ? ? ? E8">();

// ...or parse it at runtime
using parsed_t = hat::result<hat::signature, hat::signature_parse_error>;
parsed_t runtime_pattern = hat::parse_signature("48 8D 05 ? ? ? ? E8");

// Scan for this pattern using your CPU's vectorization features
auto begin = /* a contiguous iterator over std::byte */;
auto end = /* ... */;
hat::scan_result result = hat::find_pattern(begin, end, pattern);

// Scan a section in the process's base module
hat::scan_result result = hat::find_pattern(pattern, ".text");

// Or another module loaded into the process
std::optional<hat::process::module> ntdll = hat::process::get_module("ntdll.dll");
assert(ntdll.has_value());
hat::scan_result result = hat::find_pattern(pattern, *ntdll, ".text");

// Get the address pointed at by the pattern
const std::byte* address = result.get();

// Resolve an RIP relative address at a given offset
// 
//   | signature matches here
//   |        | relative address located at +3
//   v        v
//   48 8D 05 BE 53 23 01    lea  rax, [rip+0x12353be]
//
const std::byte* relative_address = result.rel(3);

Accessing offsets

#include <libhat/Access.hpp>

// An example struct and it's member offsets
struct S {
    uint32_t a{}; // 0x0
    uint32_t b{}; // 0x4
    uint32_t c{}; // 0x8
    uint32_t d{}; // 0xC
};

S s;

// Obtain a mutable reference to 's.b' via it's offset
uint32_t& b = hat::member_at<uint32_t>(&s, 0x4);

// If the provided pointer is const, the returned reference is const
const uint32_t& b = hat::member_at<uint32_t>(&std::as_const(s), 0x4);

Writing to protected memory

#include <libhat/MemoryProtector.hpp>

uintptr_t* vftable = ...;       // Pointer to a virtual function table in read-only data
size_t target_func_index = ...; // Index to an interesting function

// Use memory_protector to enable write protections
hat::memory_protector prot{
    (uintptr_t) &vftable[target_func_index],        // a pointer to the target memory
    sizeof(uintptr_t),                              // the size of the memory block
    hat::protection::Read | hat::protection::Write  // the new protection flags
};

// Overwrite function table entry to redirect to a custom callback
vftable[target_func_index] = (uintptr_t) my_callback;

// On scope exit, original protections will be restored
prot.~memory_protector(); // compiler generated