Support imports by ordinal value.

fancycode · fancycode · commit 6276f4426dd6 · 2015-08-21T22:19:28.000+02:00
Code based on pull-request fancycode#28.
diff --git a/MemoryModule.c b/MemoryModule.c
@@ -584,9 +584,7 @@ HMEMORYMODULE MemoryLoadLibraryEx(const void *data,
 FARPROC MemoryGetProcAddress(HMEMORYMODULE module, LPCSTR name)
 {
     unsigned char *codeBase = ((PMEMORYMODULE)module)->codeBase;
-    int idx=-1;
-    DWORD i, *nameRef;
-    WORD *ordinal;
+    int idx;
     PIMAGE_EXPORT_DIRECTORY exports;
     PIMAGE_DATA_DIRECTORY directory = GET_HEADER_DICTIONARY((PMEMORYMODULE)module, IMAGE_DIRECTORY_ENTRY_EXPORT);
     if (directory->Size == 0) {
@@ -602,20 +600,32 @@ FARPROC MemoryGetProcAddress(HMEMORYMODULE module, LPCSTR name)
         return NULL;
     }
 
-    // search function name in list of exported names
-    nameRef = (DWORD *) (codeBase + exports->AddressOfNames);
-    ordinal = (WORD *) (codeBase + exports->AddressOfNameOrdinals);
-    for (i=0; i<exports->NumberOfNames; i++, nameRef++, ordinal++) {
-        if (_stricmp(name, (const char *) (codeBase + (*nameRef))) == 0) {
-            idx = *ordinal;
-            break;
+    if (HIWORD(name) == 0) {
+        // load function by ordinal value
+        if (LOWORD(name) < exports->Base) {
+            SetLastError(ERROR_PROC_NOT_FOUND);
+            return NULL;
         }
-    }
 
-    if (idx == -1) {
-        // exported symbol not found
-        SetLastError(ERROR_PROC_NOT_FOUND);
-        return NULL;
+        idx = LOWORD(name) - exports->Base;
+    } else {
+        // search function name in list of exported names
+        DWORD i;
+        DWORD *nameRef = (DWORD *) (codeBase + exports->AddressOfNames);
+        WORD *ordinal = (WORD *) (codeBase + exports->AddressOfNameOrdinals);
+        idx = -1;
+        for (i=0; i<exports->NumberOfNames; i++, nameRef++, ordinal++) {
+            if (_stricmp(name, (const char *) (codeBase + (*nameRef))) == 0) {
+                idx = *ordinal;
+                break;
+            }
+        }
+
+        if (idx == -1) {
+            // exported symbol not found
+            SetLastError(ERROR_PROC_NOT_FOUND);
+            return NULL;
+        }
     }
 
     if ((DWORD)idx > exports->NumberOfFunctions) {
diff --git a/MemoryModule.h b/MemoryModule.h
@@ -63,7 +63,8 @@ HMEMORYMODULE MemoryLoadLibraryEx(const void *,
     void *);
 
 /**
- * Get address of exported method.
+ * Get address of exported method. Supports loading both by name and by
+ * ordinal value.
  */
 FARPROC MemoryGetProcAddress(HMEMORYMODULE, LPCSTR);
 
diff --git a/tests/LoadDll.cpp b/tests/LoadDll.cpp
@@ -16,6 +16,7 @@ BOOL LoadFromMemory(char *filename)
     size_t size;
     HMEMORYMODULE handle;
     addNumberProc addNumber;
+    addNumberProc addNumber2;
     HMEMORYRSRC resourceInfo;
     DWORD resourceSize;
     LPVOID resourceData;
@@ -45,9 +46,31 @@ BOOL LoadFromMemory(char *filename)
         goto exit;
     }
 
+    addNumber = (addNumberProc)MemoryGetProcAddress(handle, NULL);
+    if (addNumber != NULL) {
+        _tprintf(_T("MemoryGetProcAddress(NULL) returned %p\n"), addNumber);
+        result = FALSE;
+        goto exit;
+    }
+
+    addNumber = (addNumberProc)MemoryGetProcAddress(handle, reinterpret_cast<LPCTSTR>(0xff));
+    if (addNumber != NULL) {
+        _tprintf(_T("MemoryGetProcAddress(0xff) returned %p\n"), addNumber);
+        result = FALSE;
+        goto exit;
+    }
+
     addNumber = (addNumberProc)MemoryGetProcAddress(handle, "addNumbers");
     _tprintf(_T("From memory: %d\n"), addNumber(1, 2));
 
+    // the DLL only exports one function, try to load by ordinal value
+    addNumber2 = (addNumberProc)MemoryGetProcAddress(handle, reinterpret_cast<LPCTSTR>(0x01));
+    if (addNumber != addNumber2) {
+        _tprintf(_T("MemoryGetProcAddress(0x01) returned %p (expected %p)\n"), addNumber2, addNumber);
+        result = FALSE;
+        goto exit;
+    }
+
     resourceInfo = MemoryFindResource(handle, MAKEINTRESOURCE(VS_VERSION_INFO), RT_VERSION);
     _tprintf(_T("MemoryFindResource returned 0x%p\n"), resourceInfo);
 
