From 1cb0d10e200f75cd90610c1d5ecddb1cf00c2d25 Mon Sep 17 00:00:00 2001
From: _xeroxz <xerox@back.engineering>
Date: Sat, 5 Jun 2021 19:06:10 -0700
Subject: [PATCH] added generated header template example/reference

---
 src/gen_header_template.h | 73 ++++++++++++++++++++++++++++++++-------
 1 file changed, 61 insertions(+), 12 deletions(-)

diff --git a/src/gen_header_template.h b/src/gen_header_template.h
index 4a1904a..09daa4e 100644
--- a/src/gen_header_template.h
+++ b/src/gen_header_template.h
@@ -1,31 +1,80 @@
 #pragma once
 #pragma section( ".xmp2" )
 #pragma comment( linker, "/section:.xmp2,RWE" )
-using __vmcall_t = void* (*)(...);
+
+using u8 = unsigned char;
+using u16 = unsigned short;
+using u32 = unsigned int;
+using u64 = unsigned long long;
+using __vmcall_t = void *( * )( ... );
 
 namespace vm
 {
-    struct _gen_data
+    constexpr auto entry_rva = 0x1000;
+
+    enum class calls : u32
+    {
+        get_world = 0xBFFD6FE9,
+        get_hello = 0xBFFD6FDD
+    };
+
+    template < class T, class U > struct _pair_t
     {
-        unsigned char __vmcall_shell_code[3] = {0x0, 0x0, 0x0};
-    } __declspec( allocate( ".xmp2" ) ) gen_data;
+        T first;
+        U second;
+    };
 
-    inline __vmcall_t __vmcall = reinterpret_cast< __vmcall_t >( gen_data.__vmcall_shell_code );
+    inline _pair_t< u8, calls > call_map[ 2 ] = { { 0, calls::get_world }, { 1, calls::get_hello } };
 
-    enum class calls : unsigned long long
+    struct _gen_data
     {
-        get_world = 0xBFFD6FE9,
-        get_hello = 0xBFFD6FE9
+        u8 bin[ 0x100000 ]; // this will the vmp binary...
+        u8 __vmcall_shell_code[ 2 ][ 15 ] = { {
+                                                  0x68, 0xE9, 0xD6, 0xFF, 0x0B, // push xxxx
+                                                  0x68, 0xE9, 0xD6, 0xFF, 0x0B, // push xxxx
+                                                  0xE9, 0x00, 0x00, 0x00, 0x00  // jmp rip+xxxx
+                                              },
+
+                                              {
+                                                  0x68, 0xE9, 0xD6, 0xFF, 0x0B, // push xxxx
+                                                  0x68, 0xE9, 0xD6, 0xFF, 0x0B, // push xxxx
+                                                  0xE9, 0x00, 0x00, 0x00, 0x00  // jmp rip+xxxx
+                                              } };
+
+        bool init()
+        {
+            for ( auto idx = 0u; idx < ( sizeof( __vmcall_shell_code ) / 15 ); ++idx )
+            {
+                *reinterpret_cast< u32 * >( &__vmcall_shell_code[ idx ][ 1 ] ) =
+                    static_cast< u32 >( call_map[ idx ].second );
+
+                *reinterpret_cast< u32 * >( &__vmcall_shell_code[ idx ][ 6 ] ) =
+                    static_cast< u32 >( call_map[ idx ].second );
+
+                *reinterpret_cast< u32 * >( &__vmcall_shell_code[ idx ][ 11 ] ) = reinterpret_cast< u32 >(
+                    ( bin - ( reinterpret_cast< u64 >( &__vmcall_shell_code[ idx ] ) + 15 ) ) + entry_rva );
+            }
+
+            return true; // only a bool so i can use static/call once...
+        }
     };
 
-    template < class T, class... Ts > T call( vm::calls e_call, Ts... args )
+    __declspec( allocate( ".xmp2" ) ) inline _gen_data gen_data;
+
+    template < calls e_call, class T, class... Ts > auto call( Ts... args ) -> T
     {
-        return reinterpret_cast< T >( __vmcall( e_call, args ) );
+        static auto __init_result = gen_data.init();
+
+        __vmcall_t vmcall = nullptr;
+        for ( auto idx = 0u; idx < sizeof( call_map ) / sizeof( _pair_t< u8, calls > ); ++idx )
+            if ( call_map[ idx ].second == e_call )
+                vmcall = reinterpret_cast< __vmcall_t >( &gen_data.__vmcall_shell_code[ idx ] );
+
+        return reinterpret_cast< T >( vmcall( args... ) );
     }
 } // namespace vm
 
 int main()
 {
-    vm::call<unsigned long long>( vm::calls::get_hello );
-
+    vm::call< vm::calls::get_hello, void * >( "hello world" );
 }
\ No newline at end of file