Add support for Windows-style dynamic loading with LoadLibrary. Not

yet tested.

3 files changed, 32 insertions, 8 deletions

diff --git a/src/build-data/os/windows.txt b/src/build-data/os/windows.txt
index 140eddeba..2f344e33c 100644
--- a/src/build-data/os/windows.txt
+++ b/src/build-data/os/windows.txt
@@ -14,6 +14,7 @@ install_cmd_exec "copy"
 win32_virtual_lock
 win32_get_systemtime
 gmtime_s
+loadlibrary
 </target_features>
 
 <aliases>
diff --git a/src/utils/dyn_load/dyn_load.cpp b/src/utils/dyn_load/dyn_load.cpp
index 6d359bc01..5f3814778 100644
--- a/src/utils/dyn_load/dyn_load.cpp
+++ b/src/utils/dyn_load/dyn_load.cpp
@@ -11,10 +11,23 @@
 
 #if defined(BOTAN_TARGET_OS_HAS_DLOPEN)
   #include <dlfcn.h>
+#elif defined(BOTAN_TARGET_OS_HAS_LOADLIBRARY)
+  #include <windows.h>
 #endif
 
 namespace Botan {
 
+namespace {
+
+void raise_runtime_loader_exception(const std::string& lib_name,
+                                    const char* msg)
+   {
+   throw std::runtime_error("Failed to load " + lib_name + ": " +
+                            (msg ? msg : "Unknown error"));
+   }
+
+}
+
 Dynamically_Loaded_Library::Dynamically_Loaded_Library(
    const std::string& library) :
    lib_name(library), lib(0)
@@ -23,22 +36,25 @@ Dynamically_Loaded_Library::Dynamically_Loaded_Library(
    lib = ::dlopen(lib_name.c_str(), RTLD_LAZY);
 
    if(!lib)
-      {
-      const char* dl_err = dlerror();
-      if(!dl_err)
-         dl_err = "Unknown error";
-
-      throw std::runtime_error("Failed to load engine " + lib_name + ": " +
-                               dl_err);
-      }
+      raise_runtime_loader_exception(lib_name, dlerror());
+
+#elif defined(BOTAN_TARGET_OS_HAS_LOADLIBRARY)
+   lib = ::LoadLibrary(lib_name.c_str());
+
+   if(!lib)
+      raise_runtime_loader_exception(lib_name, "LoadLibrary failed");
 #endif
 
+   if(!lib)
+      raise_runtime_loader_exception(lib_name, "Dynamic load not supported");
    }
 
 Dynamically_Loaded_Library::~Dynamically_Loaded_Library()
    {
 #if defined(BOTAN_TARGET_OS_HAS_DLOPEN)
    ::dlclose(lib);
+#elif defined(BOTAN_TARGET_OS_HAS_LOADLIBRARY)
+   ::FreeLibrary(lib);
 #endif
    }
 
@@ -48,6 +64,8 @@ void* Dynamically_Loaded_Library::resolve_symbol(const std::string& symbol)
 
 #if defined(BOTAN_TARGET_OS_HAS_DLOPEN)
    addr = ::dlsym(lib, symbol.c_str());
+#elif defined(BOTAN_TARGET_OS_HAS_LOADLIBRARY)
+   addr = ::GetProcAddress(lib, symbol.c_str());
 #endif
 
    if(!addr)
diff --git a/src/utils/dyn_load/dyn_load.h b/src/utils/dyn_load/dyn_load.h
index 56277d3e4..c8fb31cf0 100644
--- a/src/utils/dyn_load/dyn_load.h
+++ b/src/utils/dyn_load/dyn_load.h
@@ -18,6 +18,11 @@ class Dynamically_Loaded_Library
       /**
       * Load a DLL (or fail with an exception)
       * @param lib_name name or path to a library
+      *
+      * If you don't use a full path, the search order will be defined
+      * by whatever the system linker does by default. Always using fully
+      * qualified pathnames can help prevent code injection attacks (eg
+      * via manipulation of LD_LIBRARY_PATH on Linux)
       */
       Dynamically_Loaded_Library(const std::string& lib_name);