build: libdl usage

1. properly detect.
2. Link only required components.
3. No way we don't have LoadLibrary on Windows.
4. ENABLE_PLUGIN should be controlled in autoconf.

Signed-off-by: Alon Bar-Lev <alon.barlev@gmail.com>
Acked-by: Adriaan de Jong <dejong@fox-it.com>
Acked-by: David Sommerseth <davids@redhat.com>
Signed-off-by: David Sommerseth <davids@redhat.com>

4 files changed, 15 insertions, 20 deletions

diff --git a/src/openvpn/Makefile.am b/src/openvpn/Makefile.am
index a509bba..c7626c8 100644
--- a/src/openvpn/Makefile.am
+++ b/src/openvpn/Makefile.am
@@ -95,7 +95,9 @@ openvpn_SOURCES = \
 	tun.c tun.h \
 	win32.h win32.c \
 	cryptoapi.h cryptoapi.c
+openvpn_LDADD = \
+	$(OPTIONAL_DL_LIBS)
 if WIN32
 openvpn_SOURCES += openvpn_win32_resources.rc
-openvpn_LDADD = -lgdi32 -lws2_32 -lwininet -lcrypt32 -liphlpapi -lwinmm -lshell32
+openvpn_LDADD += -lgdi32 -lws2_32 -lwininet -lcrypt32 -liphlpapi -lwinmm -lshell32
 endif
diff --git a/src/openvpn/plugin.c b/src/openvpn/plugin.c
index 4cc9c36..3f379dd 100644
--- a/src/openvpn/plugin.c
+++ b/src/openvpn/plugin.c
@@ -26,6 +26,10 @@
 
 #ifdef ENABLE_PLUGIN
 
+#ifdef HAVE_DLFCN_H
+#include <dlfcn.h>
+#endif
+
 #include "buffer.h"
 #include "error.h"
 #include "misc.h"
@@ -160,7 +164,7 @@ plugin_option_list_print (const struct plugin_option_list *list, int msglevel)
 }
 #endif
 
-#if defined(USE_LIBDL)
+#ifndef WIN32
 
 static void
 libdl_resolve_symbol (void *handle, void **dest, const char *symbol, const char *plugin_name, const unsigned int flags)
@@ -170,7 +174,7 @@ libdl_resolve_symbol (void *handle, void **dest, const char *symbol, const char
     msg (M_FATAL, "PLUGIN: could not find required symbol '%s' in plugin shared object %s: %s", symbol, plugin_name, dlerror());
 }
 
-#elif defined(USE_LOAD_LIBRARY)
+#else
 
 static void
 dll_resolve_symbol (HMODULE module, void **dest, const char *symbol, const char *plugin_name, const unsigned int flags)
@@ -191,7 +195,7 @@ plugin_init_item (struct plugin *p, const struct plugin_option *o)
   p->so_pathname = o->so_pathname;
   p->plugin_type_mask = plugin_supported_types ();
 
-#if defined(USE_LIBDL)
+#ifndef WIN32
 
   p->handle = NULL;
 #if defined(PLUGIN_LIBDIR)
@@ -220,7 +224,7 @@ plugin_init_item (struct plugin *p, const struct plugin_option *o)
 
 # define PLUGIN_SYM(var, name, flags) libdl_resolve_symbol (p->handle, (void*)&p->var, name, p->so_pathname, flags)
 
-#elif defined(USE_LOAD_LIBRARY)
+#else
 
   rel = !absolute_pathname (p->so_pathname);
   p->module = LoadLibraryW (wide_string (p->so_pathname, &gc));
@@ -427,10 +431,10 @@ plugin_close_item (struct plugin *p)
       if (p->plugin_handle)
 	(*p->close)(p->plugin_handle);
 
-#if defined(USE_LIBDL)
+#ifndef WIN32
       if (dlclose (p->handle))
 	msg (M_WARN, "PLUGIN_CLOSE: dlclose() failed on plugin: %s", p->so_pathname);
-#elif defined(USE_LOAD_LIBRARY)
+#elif defined(WIN32)
       if (!FreeLibrary (p->module))
 	msg (M_WARN, "PLUGIN_CLOSE: FreeLibrary() failed on plugin: %s", p->so_pathname);
 #endif
diff --git a/src/openvpn/plugin.h b/src/openvpn/plugin.h
index 6f75e27..4c0a1fd 100644
--- a/src/openvpn/plugin.h
+++ b/src/openvpn/plugin.h
@@ -59,9 +59,9 @@ struct plugin {
   unsigned int plugin_type_mask;
   int requested_initialization_point;
 
-#if defined(USE_LIBDL)
+#ifndef WIN32
   void *handle;
-#elif defined(USE_LOAD_LIBRARY)
+#else
   HMODULE module;
 #endif
 
diff --git a/src/openvpn/syshead.h b/src/openvpn/syshead.h
index b305660..1ad81d8 100644
--- a/src/openvpn/syshead.h
+++ b/src/openvpn/syshead.h
@@ -156,10 +156,6 @@
 #include <grp.h>
 #endif
 
-#ifdef USE_LIBDL
-#include <dlfcn.h>
-#endif
-
 #ifdef HAVE_NETDB_H
 #include <netdb.h>
 #endif
@@ -507,13 +503,6 @@ socket_defined (const socket_descriptor_t sd)
 #endif
 
 /*
- * Do we have a plug-in capability?
- */
-#if defined(USE_LIBDL) || defined(USE_LOAD_LIBRARY)
-#define ENABLE_PLUGIN
-#endif
-
-/*
  * Enable deferred authentication?
  */
 #if defined(ENABLE_DEF_AUTH) && P2MP_SERVER && defined(ENABLE_PLUGIN)