openvpn: add fallback chain for openssl

src/etc/inc/openvpn.inc

@@ -212,9 +212,21 @@ function openvpn_get_digestlist() {
 	return $digests;
 }
 
-function openvpn_get_engines() {
+function openvpn_get_engines()
+{
+	if (file_exists('/usr/local/bin/openssl')) {
+		/* use the ports version */
+		$bin_openssl = '/usr/local/bin/openssl';
+	} elseif (file_exists('/usr/bin/openssl')) {
+		/* use the base version (legacy fallback) */
+		$bin_openssl = '/usr/bin/openssl';
+	} else {
+		/* the infamous "this should never happen" */
+		log_error(_('Could not find an OpenSSL implementation on your system.'));
+	}
+
 	$openssl_engines = array('none' => 'No Hardware Crypto Acceleration');
-	exec("/usr/bin/openssl engine -t -c", $openssl_engine_output);
+	exec($bin_openssl . ' engine -t -c', $openssl_engine_output);
 	$openssl_engine_output = implode("\n", $openssl_engine_output);
 	$openssl_engine_output = preg_replace("/\\n\\s+/", "|", $openssl_engine_output);
 	$openssl_engine_output = explode("\n", $openssl_engine_output);