Framework to build dane support

[exim.git] / src / src / dane.c

diff --git a/src/src/dane.c b/src/src/dane.c
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+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2012 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This module provides TLS (aka SSL) support for Exim. The code for OpenSSL is
+based on a patch that was originally contributed by Steve Haslam. It was
+adapted from stunnel, a GPL program by Michal Trojnara. The code for GNU TLS is
+based on a patch contributed by Nikos Mavroyanopoulos. Because these packages
+are so very different, the functions for each are kept in separate files. The
+relevant file is #included as required, after any any common functions.
+
+No cryptographic code is included in Exim. All this module does is to call
+functions from the OpenSSL or GNU TLS libraries. */
+
+
+#include "exim.h"
+
+/* This module is compiled only when it is specifically requested in the
+build-time configuration. However, some compilers don't like compiling empty
+modules, so keep them happy with a dummy when skipping the rest. Make it
+reference itself to stop picky compilers complaining that it is unused, and put
+in a dummy argument to stop even pickier compilers complaining about infinite
+loops. */
+
+#ifndef EXPERIMENTAL_DANE
+static void dummy(int x) { dummy(x-1); }
+#else
+
+/* Enabling DANE without enabling TLS cannot work. Abort the compilation. */
+#ifndef SUPPORT_TLS
+#error DANE support requires that TLS support must be enabled. Abort build.
+#endif
+
+#ifdef USE_GNUTLS
+#include "dane-gnu.c"
+#else
+#include "dane-openssl.c"
+#endif
+
+
+#endif  /* EXPERIMENTAL_DANE */
+
+/* End of dane.c */