The custom ISC SPNEGO mechanism implementation is no longer needed on
the basis that all major Kerberos 5/GSSAPI (mit-krb5, heimdal and
Windows) implementations support SPNEGO mechanism since 2006.
This commit removes the custom ISC SPNEGO implementation, and removes
the option from both autoconf and win32 Configure script. Unknown
options are being ignored, so this doesn't require any special handling.
Instead of calling isc_tls_initialize()/isc_tls_destroy() explicitly use
gcc/clang attributes on POSIX and DLLMain on Windows to initialize and
shutdown OpenSSL library.
This resolves the issue when isc_nm_create() / isc_nm_destroy() was
called multiple times and it would call OpenSSL library destructors from
isc_nm_destroy().
At the same time, since we now have introduced the ctor/dtor for libisc,
this commit moves the isc_mem API initialization (the list of the
contexts) and changes the isc_mem_checkdestroyed() to schedule the
checking of memory context on library unload instead of executing the
code immediately.
As libssl depends on libcrypto, -lssl needs to precede -lcrypto in
linker invocations or else the build will fail with static OpenSSL
libraries. Adjust m4/ax_check_openssl.m4 to prevent this issue from
getting triggered when pkg-config files for OpenSSL are not available.
(cherry picked from commit 9223c7d599)
The ax_check_openssl m4 macro used OPENSSL_INCLUDES. Rename the
subst variable to OPENSSL_CFLAGS and wrap AX_CHECK_OPENSSL() in
action-if-not-found part of PKG_CHECK_MODULE check for libcrypto.
Pull and use several autoconf archive convenience macros to simplify
configure.ac.
* AX_CHECK_COMPILE_FLAG(FLAG, ...) - check whether given CFLAG works
* AX_CHECK_LINK_FLAG(FLAG, ...) - check whether given LDFLAG works
* AX_CHECK_PREPROC_FLAG(FLAG, ...) - check whether give CPPFLAG works
* AX_SAVE_FLAGS/AX_RESTORE_FLAGS - save and restore *FLAGS
Mark AndrewsandOndřej Surý
Witold KręcickiandOndřej Surý