loader.c

#include <Windows.h>

__declspec(dllexport)
DWORD WINAPI  GetIpAddrTable(void *p, long *n, BOOL o) {
	return 1;
}

void *(*mono_runtime_invoke)(void *, void *, void **, void **);
void *(*mono_method_desc_new)(const char *name, BOOL include_namespace);
void *(*mono_method_desc_search_in_image)(void *, void*);
void *(*mono_array_new)(void *, void *, uintptr_t);
void *(*mono_get_string_class)();
void *(*mono_get_root_domain)();
void *(*mono_assembly_get_image)(void *);

void *(*mono_assembly_open_full)(const char *name, int *stat, BOOL refonly);
void (*mono_register_bundled_assemblies)(void **);
void (*mono_jit_exec)(void *dom, void *ass, int, const char**);
void (*mono_profiler_install)(void *, void *);
void (*mono_profiler_set_events)(int mask);
void (*mono_profiler_install_module)(void *, void *, void *, void *);
void (*mono_profiler_install_assembly)(void *, void *, void *, void *);


// gets called for every dll module loaded, memory or not.
// we need to skip one call for mscorlib to get a chance, but no further so we can hijack implicit System.*
static int count = 0;
static void hook(void *prof, void *ldrimg) {
	count++;
	if (count != 2)
		return;
	MessageBoxA(NULL, "Intro", "Fatal", MB_OK);
	mono_profiler_set_events(0);
	void *ass = mono_assembly_open_full("patch.exe", NULL, FALSE);
	if (!ass) {
		MessageBoxA(NULL, "Failed to load embedded assembly. The game will run without patch.", "Fatal", MB_OK);
		return;
	}
	void *domain = mono_get_root_domain();
	void *image = mono_assembly_get_image(ass);
	void *desc = mono_method_desc_new("*:Main", FALSE);
	void *meth = mono_method_desc_search_in_image(desc, image);
	void *args = mono_array_new(domain, mono_get_string_class(), 0);
	mono_runtime_invoke(meth, NULL, args, NULL);
}

BOOL APIENTRY DllMain(HMODULE hModule, DWORD  ul_reason_for_call, LPVOID lpReserved)
{
	if (ul_reason_for_call != DLL_PROCESS_ATTACH)
		return TRUE;

	// load mono
	wchar_t name[MAX_PATH + 1];
	int len = GetModuleFileName(NULL, name, MAX_PATH);
	lstrcpy(name + len - 4, L"_Data\\Mono\\mono.dll");
	HMODULE mono = LoadLibrary(name);
	if (!mono) {
		lstrcpy(name + len - 4 + 5, L"\\EmbedRuntime\\mono.dll");
		mono = LoadLibrary(name);
		if (!mono) {
			MessageBoxA(NULL, "Can't find mono.dll. Is this the right game folder?", "Fatal", MB_OK | MB_ICONASTERISK);
			return FALSE;
		}
	}

#define LOAD(n) \
	n = (void*)GetProcAddress(mono, #n); \
	if (!n) { \
		MessageBoxA(NULL, #n, "Method missing", MB_OK | MB_ICONASTERISK); \
		ExitProcess(1); \
	}
	LOAD(mono_jit_exec);
	LOAD(mono_register_bundled_assemblies);
	LOAD(mono_assembly_open_full);	
	LOAD(mono_assembly_get_image);
	LOAD(mono_profiler_install);
	LOAD(mono_profiler_set_events);
	LOAD(mono_profiler_install_module);
	LOAD(mono_profiler_install_assembly);
	LOAD(mono_runtime_invoke);
	LOAD(mono_method_desc_new);
	LOAD(mono_method_desc_search_in_image);
	LOAD(mono_array_new);
	LOAD(mono_get_string_class);
	LOAD(mono_get_root_domain);

	// load assembly
	HRSRC hres = FindResource(hModule, MAKEINTRESOURCE(12123), MAKEINTRESOURCE(RT_RCDATA));
	if (!hres) {
		MessageBoxA(NULL, "Failed to load embedded resource. The game will run without patch.", "Fatal", MB_OK);
		return TRUE;
	}

	HGLOBAL hglob = LoadResource(hModule, hres);
	void *res_data = (char*)LockResource(hglob);
	int stat = 0;
	static struct {
		const char *name;
		unsigned char *data;
		unsigned int len;
	} info, *infol[2] = { &info, NULL };
	info.name = "patch.exe";
	info.data = LockResource(hglob);
	info.len = SizeofResource(hModule, hres);


	// register the assembly
	mono_register_bundled_assemblies(&infol[0]);

	// register assembly load hook
	mono_profiler_install(NULL, NULL);
	mono_profiler_set_events(1 << 2); // module load events
	mono_profiler_install_module(&hook, NULL, NULL, NULL);
	//mono_profiler_install_assembly(&hook, NULL, NULL, NULL); TBD
	return TRUE;
}