Crate detour [−] [src]

A cross-platform detour library written in Rust.

Intro

This library provides a thread-safe, inline detouring functionality by disassembling and patching functions during runtime, using assembly opcodes allocated within executable memory. It modifies the target functions and replaces their prolog with an unconditional jump.

Beyond the basic functionality this library handles several different edge cases:

  • Relative branches.
  • RIP relative operands.
  • Detects NOP-padding.
  • Relay for large offsets (>2GB)
  • Supports hot patching.

Detours

Three different types of detours are provided:

  • Static: A static & type-safe interface. Thanks to its static nature it can accept a closure as its second argument, but on the other hand, only one detour can be active at a time.

  • Generic: A type-safe interface — the same prototype is enforced for both the target and the detour. It is also enforced when invoking the original target.

  • Raw: The underlying building block that the others types abstract upon. It has no type-safety and interacts with raw pointers.
    It should be avoided unless the types used aren't known until runtime.

All detours dereferences to the Detour interface, which exposes several methods, and enforces Send + Sync.

Features

  • nightly: Enabled by default. Required for the static detours, due to usage of const_fn & unboxed_closures. The feature also enables a more extensive test suite.

Platforms

  • Both x86 & x86-64 are supported.

Procedure

To illustrate a detour on an x86 platform:

0 int return_five() {
1     return 5;
00400020 [b8 05 00 00 00] mov eax, 5
00400025 [c3]             ret
2 }
3
4 int detour_function() {
5     return 10;
00400040 [b8 0A 00 00 00] mov eax, 10
00400045 [c3]             ret
6 }

To detour return_five the library by default tries to replace five bytes with a relative jump (the optimal scenario), which works in this case. Executable memory will be allocated for the instruction and the function's prolog will be replaced.

0 int return_five() {
1     return detour_function();
00400020 [e9 16 00 00 00] jmp 1b <detour_function>
00400025 [c3]             ret
2 }
3
4 int detour_function() {
5     return 10;
00400040 [b8 0A 00 00 00] mov eax, 10
00400045 [c3]             ret
6 }

Beyond what is shown here, a trampoline is also generated so the original function can be called regardless whether the function is hooked or not.

Macros

static_detours

A macro for defining type-safe detours.

Structs

Detour

An architecture-independent implementation of a base detour.
GenericDetour

A type-safe wrapper around Detour.
RawDetour

A type-less wrapper around Detour.
StaticDetour

A type-safe static detour.
StaticDetourController

An instantiator for StaticDetour.

Enums

Error

Traits

Function

Trait representing a function that can be used as a target or detour for detouring.
HookableWith

Trait indicating that Self can be detoured by the given function D.