configure: disable engines if OPENSSL_NO_ENGINE is defined

Starting with LibreSSL 3.8.1 the engines have been removed which causes
the OpenVPN build to fail. This can be solved during configure by
checking if OPENSSL_NO_ENGINE is defined in opensslconf.h.

Signed-off-by: orbea <orbea@riseup.net>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20230909134956.5902-1-orbea@riseup.net>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26994.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 34bf473e19118eecf525e7401ef37b1cbf661e67)

diff --git a/configure.ac b/configure.ac
index 16c40bb58806ddcc5cc67dd516fdad5ff7b7df23..931aa334f35309e7cba1884ee1f642b348df3e07 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -930,11 +930,17 @@ if test "${with_crypto_library}" = "openssl"; then
                                    [AC_LANG_PROGRAM(
                                            [[
            #include <openssl/opensslv.h>
+           #include <openssl/opensslconf.h>
                                            ]],
                                            [[
            /*       Version encoding: MNNFFPPS - see opensslv.h for details */
            #if OPENSSL_VERSION_NUMBER >= 0x30000000L
-           #error Engine supported disabled by default in OpenSSL 3.0+
+           #error Engine support disabled by default in OpenSSL 3.0+
+           #endif
+
+           /*       BoringSSL and LibreSSL >= 3.8.1 removed engine support */
+           #ifdef OPENSSL_NO_ENGINE
+           #error Engine support disabled in openssl/opensslconf.h
            #endif
                                            ]]
                                    )],