SDK: Add FProperty::PropertyFlags bruteforcer

praydog · Dec 25, 2023 · ac82f2a · ac82f2a
1 parent 13f5155
commit ac82f2a
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Showing 3 changed files with 77 additions and 0 deletions.
diff --git a/shared/sdk/FProperty.cpp b/shared/sdk/FProperty.cpp
@@ -1,5 +1,8 @@
 #include <spdlog/spdlog.h>
 
+#include "UObjectArray.hpp"
+#include "UFunction.hpp"
+
 #include "UProperty.hpp"
 #include "FProperty.hpp"
 
@@ -42,4 +45,70 @@ void FProperty::bruteforce_fproperty_offset(FProperty* x_prop, FProperty* y_prop
         SPDLOG_ERROR("[FProperty] Failed to bruteforce offset field");
     }
 }
+
+void FProperty::update_offsets() try {
+    if (s_attempted_update_offsets) {
+        return;
+    }
+
+    s_attempted_update_offsets = true;
+    SPDLOG_INFO("[FProperty] Updating offsets...");
+
+    // Get ActorComponent class
+    const auto actor_component_class = sdk::find_uobject<sdk::UClass>(L"Class /Script/Engine.ActorComponent");
+
+    if (actor_component_class == nullptr) {
+        SPDLOG_ERROR("[FProperty] Failed to find ActorComponent class");
+        return;
+    }
+
+    // Find IsActive function
+    const auto is_active_function = actor_component_class->find_function(L"IsActive");
+
+    if (is_active_function == nullptr) {
+        SPDLOG_ERROR("[FProperty] Failed to find IsActive function");
+        return;
+    }
+
+    // Get first parameter
+    const auto first_param = is_active_function->get_child_properties();
+
+    if (first_param == nullptr) {
+        SPDLOG_ERROR("[FProperty] Failed to find first parameter");
+        return;
+    }
+
+    const auto start_raw = std::max(FField::s_next_offset, FField::s_name_offset) + sizeof(void*);
+
+    // Alignup to sizeof(void*)
+    const auto start = (start_raw + sizeof(void*) - 1) & ~(sizeof(void*) - 1);
+
+    constexpr auto cpf_param = 0x80;
+    constexpr auto cpf_out_param = 0x100;
+    constexpr auto cpf_return_param = 0x400;
+    constexpr auto cpf_is_pod = 0x40000000; // CPF_IsPlainOldData
+
+    // 4 flags that will definitely always be set
+    const auto wanted_flags = cpf_param | cpf_out_param | cpf_return_param | cpf_is_pod;
+
+    for (auto i = start; i < 0x200; i += sizeof(void*)) try {
+        const auto value = *(uint64_t*)((uintptr_t)first_param + i);
+        if ((value & wanted_flags) == wanted_flags) {
+            SPDLOG_INFO("[FProperty] Found PropertyFlags offset at 0x{:X} (full value {:x})", i, value);
+            s_property_flags_offset = i;
+            break;
+        }
+    } catch (...) {
+        continue;
+    }
+
+    if (s_property_flags_offset == 0) {
+        SPDLOG_ERROR("[FProperty] Failed to find PropertyFlags offset");
+        return;
+    }
+
+    SPDLOG_INFO("[FProperty] done");
+} catch(...) {
+    SPDLOG_ERROR("[FProperty] Failed to update offsets");
+}
 }
diff --git a/shared/sdk/FProperty.hpp b/shared/sdk/FProperty.hpp
@@ -25,11 +25,18 @@ class FProperty : public FField {
         return (T*)((uintptr_t)object + get_offset());
     }
 
+    uint64_t get_property_flags() const {
+        return *(uint64_t*)((uintptr_t)this + s_property_flags_offset);
+    }
+
     // Given xyz props from FVector, find the offset which matches up with all of them
     static void bruteforce_fproperty_offset(FProperty* x_prop, FProperty* y_prop, FProperty* z_prop);
+    static void update_offsets(); // for other offsets like PropertyFlags
 
 protected:
+    static inline bool s_attempted_update_offsets{false};
     static inline uint32_t s_offset_offset{0x0}; // idk
+    static inline uint32_t s_property_flags_offset{0x0}; // idk
 
     friend class UStruct;
     friend class UProperty;

diff --git a/shared/sdk/UObjectArray.cpp b/shared/sdk/UObjectArray.cpp
@@ -419,6 +419,7 @@ FUObjectArray* FUObjectArray::get() try {
         sdk::FObjectProperty::update_offsets();
         sdk::FArrayProperty::update_offsets();
         sdk::FEnumProperty::update_offsets();
+        sdk::FProperty::update_offsets();
         //sdk::UObjectHashTables::get();
 
 #ifdef TESTING_GUOBJECTARRAY