C++ Alternative to GetProcAddress
Code:
void* GetFuncAddress(HMODULE hModule, const char* FunctionName)
{
char *modb = (char *)hModule;
IMAGE_DOS_HEADER *dos_header = (IMAGE_DOS_HEADER *)modb;
IMAGE_NT_HEADERS *nt_headers = (IMAGE_NT_HEADERS *)(modb + dos_header->e_lfanew);
IMAGE_OPTIONAL_HEADER *opt_header = &nt_headers->OptionalHeader;
IMAGE_DATA_DIRECTORY *exp_entry = (IMAGE_DATA_DIRECTORY *)(&opt_header->DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT]);
IMAGE_EXPORT_DIRECTORY *exp_dir = (IMAGE_EXPORT_DIRECTORY *)(modb + exp_entry->VirtualAddress);
void **func_table = (void **)(modb + exp_dir->AddressOfFunctions);
WORD *ord_table = (WORD *)(modb + exp_dir->AddressOfNameOrdinals);
char **name_table = (char **)(modb + exp_dir->AddressOfNames);
void *address = NULL;
DWORD i;
if (((DWORD)FunctionName >> 16) == 0) {
WORD ordinal = LOWORD(FunctionName);
DWORD ord_base = exp_dir->Base;
if (ordinal < ord_base || ordinal > ord_base + exp_dir->NumberOfFunctions)
return NULL;
address = (void *)(modb + (DWORD)func_table[ordinal - ord_base]);
}
else {
for (i = 0; i < exp_dir->NumberOfNames; i++) {
if (strcmp(FunctionName, modb + (DWORD)name_table[i]) == 0)
address = (void *)(modb + (DWORD)func_table[ord_table[i]]);
}
}
if ((char *)address >= (char *)exp_dir &&
(char *)address < (char *)exp_dir + exp_entry->Size) {
char *dll_name, *func_name;
HMODULE frwd_module;
dll_name = _strdup((char *)address);
if (!dll_name)
return NULL;
address = NULL;
func_name = strchr(dll_name, '.');
*func_name++ = 0;
frwd_module = GetModuleHandleA(dll_name);
if (!frwd_module)
frwd_module = LoadLibraryA(dll_name);
if (frwd_module)
address = GetFuncAddress(frwd_module, func_name);
free(dll_name);
}
return address;
}