AC_CHECK_TOOL([PKG_CONFIG], [pkg-config])

	dnl Disable support for TLS 1.0 protocol
	AC_ARG_ENABLE([tls1], AS_HELP_STRING([--disable-tls1], [disable TLS1 protocol]), [
		if test "${enableval}" = "no"; then
			AC_DEFINE([NO_TLS1], [1], [Disable TLS1 protocol])
			AC_MSG_CHECKING([for disable TLS1 protocol])
			AC_MSG_RESULT([yes])
		fi
	])

	dnl Disable support for TLS 1.1 protocol
	AC_ARG_ENABLE([tls1_1], AS_HELP_STRING([--disable-tls1_1], [disable TLS1.1 protocol]), [
		if test "${enableval}" = "no"; then
			AC_DEFINE([NO_TLS1_1], [1], [Disable TLS1.1 protocol])
			AC_MSG_CHECKING([for disable TLS1.1 protocol])
			AC_MSG_RESULT([yes])
		fi
	])

	dnl Disable support for TLS 1.2 protocol
	AC_ARG_ENABLE([tls1_2], AS_HELP_STRING([--disable-tls1_2], [disable TLS1.2 protocol]), [
		if test "${enableval}" = "no"; then
			AC_DEFINE([NO_TLS1_2], [1], [Disable TLS1.2 protocol])
			AC_MSG_CHECKING([for disable TLS1.2 protocol])
			AC_MSG_RESULT([yes])
		fi
	])

	dnl Disable support for TLS 1.3 protocol
	AC_ARG_ENABLE([tls1_3], AS_HELP_STRING([--disable-tls1_3], [disable TLS1.3 protocol]), [
		if test "${enableval}" = "no"; then
			AC_DEFINE([NO_TLS1_3], [1], [Disable TLS1.3 protocol])
			AC_MSG_CHECKING([for disable TLS1.3 protocol])
			AC_MSG_RESULT([yes])
		fi
	])


	dnl Determine if we have been asked to use a fast path if possible
	AC_ARG_ENABLE([ssl-fastpath], AS_HELP_STRING([--enable-ssl-fastpath],
		[enable using the underlying file descriptor for talking directly to the SSL library]), [

	AC_ARG_WITH([openssl-includedir],
		AS_HELP_STRING([--with-openssl-includedir=<dir>],
			[path to include directory of OpenSSL or LibreSSL installation]
		), [
			opensslincludedir="$withval"
		], [
			if test ! -z "$openssldir"; then
				if test -f "${openssldir}/include/openssl/ssl.h"; then
					opensslincludedir="${openssldir}/include/openssl"
				else
					opensslincludedir="${openssldir}/include"
				fi
			else
				opensslincludedir=''
			fi
		]
	)
	AC_MSG_CHECKING([for OpenSSL include directory])
	AC_MSG_RESULT($opensslincludedir)

	dnl Set SSL include vars
	if test ! -z "$opensslincludedir"; then
		if test -f "$opensslincludedir/ssl.h"; then
			TCLTLS_SSL_CFLAGS="-I$opensslincludedir"
			TCLTLS_SSL_INCLUDES="-I$opensslincludedir"
			AC_MSG_CHECKING([for ssl.h])
			AC_MSG_RESULT([yes])
		else
			AC_MSG_CHECKING([for ssl.h])
			AC_MSG_RESULT([no])
			AC_MSG_ERROR([Unable to locate ssl.h])
		fi



	fi

	dnl Set SSL lib files path
	AC_ARG_WITH([openssl-libdir],
		AS_HELP_STRING([--with-openssl-libdir=<dir>],
			[path to lib directory of OpenSSL or LibreSSL installation]
		), [

	AC_MSG_RESULT($openssllibdir)

	dnl Set SSL lib vars
	if test ! -z "$openssllibdir"; then
		if test -f "$openssllibdir/libssl${SHLIB_SUFFIX}"; then
			if test "${TCLEXT_TLS_STATIC_SSL}" == 'no'; then
				TCLTLS_SSL_LIBS="-L$openssllibdir -lcrypto -lssl"
			#else
				# Linux and Solaris
				#TCLTLS_SSL_LIBS="-Wl,-Bstatic `$PKG_CONFIG --static --libs crypto ssl` -Wl,-Bdynamic"
				# HPUX
				# -Wl,-a,archive ... -Wl,-a,shared_archive
			fi
		else
			AC_MSG_ERROR([Unable to locate libssl${SHLIB_SUFFIX}])
		fi


	fi








	dnl Set location of pkgconfig files
	AC_ARG_WITH([openssl-pkgconfig],
		AS_HELP_STRING([--with-openssl-pkgconfig=<dir>],
			[path to pkgconfigdir directory for OpenSSL or LibreSSL]
		), [
			opensslpkgconfigdir="$withval"
		], [
			if test -d ${libdir}/../pkgconfig; then
				opensslpkgconfigdir="$libdir/../pkgconfig"
			else
				opensslpkgconfigdir=''
			fi
		]
	)
	AC_MSG_CHECKING([for OpenSSL pkgconfig])
	AC_MSG_RESULT($opensslpkgconfigdir)


	# Use Package Config tool to get config

		dnl Temporarily update PKG_CONFIG_PATH
		PKG_CONFIG_PATH_SAVE="${PKG_CONFIG_PATH}"
		if test -n "${opensslpkgconfigdir}"; then
			if ! test -f "${opensslpkgconfigdir}/openssl.pc"; then
				AC_MSG_ERROR([Unable to locate ${opensslpkgconfigdir}/openssl.pc])
			fi

			PKG_CONFIG_PATH="${opensslpkgconfigdir}:${PKG_CONFIG_PATH}"
			export PKG_CONFIG_PATH
		fi
		if test -z "$TCLTLS_SSL_LIBS"; then
			TCLTLS_SSL_LIBS="`"${PKG_CONFIG}" openssl --libs $pkgConfigExtraArgs`" || AC_MSG_ERROR([Unable to get OpenSSL Configuration])
		fi
		if test -z "$TCLTLS_SSL_CFLAGS"; then
			TCLTLS_SSL_CFLAGS="`"${PKG_CONFIG}" openssl --cflags-only-other $pkgConfigExtraArgs`" || AC_MSG_ERROR([Unable to get OpenSSL Configuration])
		fi
		if test -z "$TCLTLS_SSL_INCLUDES"; then
			TCLTLS_SSL_INCLUDES="`"${PKG_CONFIG}" openssl --cflags-only-I $pkgConfigExtraArgs`" || AC_MSG_ERROR([Unable to get OpenSSL Configuration])
		fi
		PKG_CONFIG_PATH="${PKG_CONFIG_PATH_SAVE}"
	fi


	dnl Fallback settings for OpenSSL includes and libs
	if test -z "$TCLTLS_SSL_LIBS"; then
		TCLTLS_SSL_LIBS="-lcrypto -lssl"
	fi
	if test -z "$TCLTLS_SSL_CFLAGS"; then
		TCLTLS_SSL_CFLAGS=""
	fi
	if test -z "$TCLTLS_SSL_INCLUDES"; then
		if test -d /usr/include/openssl; then
			TCLTLS_SSL_INCLUDES="-I/usr/include/openssl"
		else
			TCLTLS_SSL_INCLUDES="-I/usr/include"
		fi
	fi

	dnl Include config variables in --help list and make available to be substituted via AC_SUBST.
	AC_ARG_VAR([TCLTLS_SSL_CFLAGS], [C compiler flags for OpenSSL or LibreSSL])
	AC_ARG_VAR([TCLTLS_SSL_INCLUDES], [C compiler include paths for OpenSSL or LibreSSL])
	AC_ARG_VAR([TCLTLS_SSL_LIBS], [libraries to pass to the linker for OpenSSL or LibreSSL])
])