configure.ac

# configure.ac for the libcoap package
#
# Copyright (C) 2010-2015 Olaf Bergmann <bergmann@tzi.org>
#           (C) 2015-2018 Carsten Schoenert <c.schoenert@t-online.de>
#
# Please run 'autogen.sh' to let autoconf produce a configure script.

# Define the libcoap software version here. Note! The libtool versions are
# defined later.
m4_define([libcoap_major_version], [4])
m4_define([libcoap_minor_version], [3])
m4_define([libcoap_micro_version], [0])

# define an appending release state if needed, for example for pre-releases
# like 'alpha' or 'rc1', for a full release keep the value empty!
m4_define([libcoap_release_state], [beta])

# concatenate the full libcoap version string
m4_define([libcoap_version], [m4_format([%s.%s.%s%s], libcoap_major_version, libcoap_minor_version, libcoap_micro_version, libcoap_release_state)])

AC_INIT([libcoap], [libcoap_version], [libcoap-developers@lists.sourceforge.net], [libcoap], [https://libcoap.net/])
AC_PREREQ([2.64])
AM_INIT_AUTOMAKE([1.10 -Wall no-define no-dist-gzip dist-bzip2])
PKG_PROG_PKG_CONFIG([0.20])
AM_SILENT_RULES([yes])
AC_HEADER_ASSERT

# Generate one configuration header file for building the library itself with
# an auto generated template. We need later a second one (include/libcoap.h)
# that will be installed alongside the library.
AC_CONFIG_HEADERS([coap_config.h])

AC_PROG_CC
AM_PROG_CC_C_O
AC_PROG_SED
AC_CONFIG_MACRO_DIR([m4])
m4_pattern_allow([AM_PROG_AR])
AM_PROG_AR

AC_C_BIGENDIAN

# enable the automatically build of shared and static libraries
LT_INIT([shared static])

# Setting the libtool versioning
###################################################################################
#                                                                                 #
#  To set the version of the library, libtool provides the -version-info          #
#  parameter, which accepts three numbers, separated by colons, that are called   #
#  respectively, current, revision and age. Both their name and their behavior,   #
#  nowadays, have to be considered fully arbitrary, as the explanation provided   #
#  in the official documentation is confusing to say the least, and can be, in    #
#  some cases, considered completely wrong.                                       #
#  https://autotools.io/libtool/version.html                                      #
#                                                                                 #
###################################################################################
#
# How to work with the libtool versioning?
#
# Follow the following steps from top to bottom. This means always start at point 1
# if you plan to make a release and change the values.
# Every new library starts with a version 'current'  (short 'c') = 0
#                                         'revision' (short 'r') = 0
#                                         'age'      (short 'a') = 0
#
# Update the libtool versioning only after the release of a public release of libcoap.
# Go through the following checklist from top to bottom and check your needs, following
# the reminded changes if you can say "Yes" for specific check.
#
# 1. Only existing code has changed, no functional changes
#    If the library source code has changed but *no* new symbols were added at all
#    since the last update, then increment revision (c:r:a becomes c:r+1:a).
#    This is usually happen if the existing source of a function was changed for
#    bug fixing e.g.
#
#  --> Increase the 'LT_LIBCOAP_REVISION' value with *every* new software release
#      within one release cycle.
#
# 2. Interfaces were added, functions have changed or are removed
#    If any interfaces [exported functions or data] have been added, got internal
#    changes that implies a different behavior or removed and by this the visible
#    symbols have changed since the last update, increment current, and set
#    revision to 0 (c:r:a becomes c+1:r=0:a).
#
#  --> Increase the 'LT_LIBCOAP_CURRENT' value whenever as an interface has been added
#      or removed. This implies also a API change! You mostly have to change the
#      'libcoap_major_version' or at least 'libcoap_minor_version' then too!
#  --> Set 'LT_LIBCOAP_REVISION' to 0.
#
# 3. Interfaces were added but none removed or changed
#    If any interfaces have been added since the last public release and non of the
#    existing interfaces were removed and existing interfaces have not changed internal
#    functionality then the new library is backward compatible. Existing binaries can
#    use the new library the same than as the existing old library without loosing
#    existing functionality or breakage.
#    Increase age by 1 (c:r:a becomes c:r:a+1).
#
#  --> Increase the 'LT_LIBCOAP_AGE' value only if the changes made to the ABI are
#      backward compatible.
#
# 4. Interfaces were removed or have functional changes
#    If any interfaces within the library have been removed since the last public
#    release or got some internal changes that let the interface act different than
#    before, then set age to 0. The library isn't backwards compatible.
#
#  --> Set 'LT_LIBCOAP_AGE' to 0.

LT_LIBCOAP_CURRENT=2
LT_LIBCOAP_REVISION=1
LT_LIBCOAP_AGE=0
LIBCOAP_SO_VERSION=$LT_LIBCOAP_CURRENT.$LT_LIBCOAP_REVISION.$LT_LIBCOAP_AGE

# Announce the libtool version
AC_SUBST(LT_LIBCOAP_CURRENT)
AC_SUBST(LT_LIBCOAP_REVISION)
AC_SUBST(LT_LIBCOAP_AGE)
AC_SUBST(LIBCOAP_SO_VERSION)

# Defining the API Version
LIBCOAP_API_VERSION=2
AC_SUBST(LIBCOAP_API_VERSION)

# Define a numeric version string
m4_define([version_number],
          [m4_format([%u%03u%03u],
                     libcoap_major_version,
                     libcoap_minor_version,
                     libcoap_micro_version)])
LIBCOAP_VERSION=version_number
AC_SUBST(LIBCOAP_VERSION)

# Adding some default warning options for code QS
# see https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
# and http://www.gnu.org/software/automake/manual/html_node/Flag-Variables-Ordering.html
WARNING_CFLAGS="\
-pedantic \
-Wall \
-Wcast-qual \
-Wextra \
-Wformat-security \
-Winline \
-Wmissing-declarations \
-Wmissing-prototypes \
-Wnested-externs \
-Wpointer-arith \
-Wshadow \
-Wstrict-prototypes \
-Wswitch-default \
-Wswitch-enum \
-Wunused \
-Wwrite-strings \
"

# check whether or not the compiler supports -Wlogical-op (clang does not...)
AX_CHECK_COMPILE_FLAG([-Wlogical-op], [WARNING_CFLAGS="$WARNING_CFLAGS -Wlogical-op"],,[-Werror])
AX_CHECK_COMPILE_FLAG([-fdiagnostics-color], [CFLAGS="$CFLAGS -fdiagnostics-color"],,[-Werror])
AX_CHECK_COMPILE_FLAG([-Wunused-result], [WARNING_CFLAGS="$WARNING_CFLAGS -Wunused-result"])

AC_SUBST([WARNING_CFLAGS])

AX_CHECK_LINK_FLAG([-Wl,--version-script=${srcdir}/libcoap-${LIBCOAP_API_VERSION}.map],
                   [libcoap_SYMBOLS="-Wl,--version-script=\$(srcdir)/libcoap-\$(LIBCOAP_API_VERSION).map"],
                   [libcoap_SYMBOLS="-export-symbols \$(top_builddir)/libcoap-\$(LIBCOAP_API_VERSION).sym"])

AC_SUBST(libcoap_SYMBOLS)

# configure options
# __documentation__

AC_ARG_ENABLE([documentation],
              [AS_HELP_STRING([--enable-documentation],
                              [Enable building all the documentation [default=yes]])],
              [build_documentation="$enableval"],
              [build_documentation="yes"])

AM_CONDITIONAL(BUILD_DOCUMENTATION, [test "x$build_documentation" = "xyes"])

doxygen_version_required=1.7.0
dot_version_required=2.26.0

AC_ARG_ENABLE([doxygen],
              [AS_HELP_STRING([--enable-doxygen],
                              [Enable building the doxygen documentation [default=yes]])],
              [build_doxygen="$enableval"],
              [build_doxygen="yes"])

if test -z "$enable_doxygen"; then
    if test "x$enable_documentation" = "xno"; then
        build_doxygen="no"
    fi
fi

if test "x$build_doxygen" = "xyes"; then
    # Check for doxygen
    AC_PATH_PROGS([DOXYGEN], [doxygen])
    if test -z "$DOXYGEN"; then
        if test "x$build_doxygen" = "xyes"; then
            AC_MSG_WARN([==> You want to build the doxygen documentation but doxygen was not found!])
            AC_MSG_ERROR([==> Install the package that contains doxygen or disable the doxygen documentation using '--disable-doxygen'.])
        fi
    else
        AC_MSG_CHECKING([for compatible doxygen version (>= $doxygen_version_required)])
        doxygen_version=`$DOXYGEN --version`
        AS_VERSION_COMPARE([$doxygen_version],
                           [$doxygen_version_required],
                           [AC_MSG_RESULT([no])
                            DOXYGEN=""],
                           [AC_MSG_RESULT([yes $doxygen_version])],
                           [AC_MSG_RESULT([yes $doxygen_version])])
        if test "x$DOXYGEN" = "x" -a "x$build_doxygen" = "xyes"; then
            AC_MSG_WARN([==> Doxygen $doxygen_version too old. Doxygen >= $doxygen_version_required required for documentation build.])
            AC_MSG_ERROR([==> Install required doxygen version or disable the doxygen documentation using '--disable-doxygen'.])
        else
            # we found doxygen and the version is valid
            DOC_DIR=doc
            AC_SUBST(DOC_DIR)
            # now checking dot (needed for graphics)
            AC_PATH_PROG([DOT], [dot])
            if test "x$DOT" = "x"; then
                AC_MSG_WARN([==> dot not found - continuing without DOT support])
                AC_MSG_WARN([==> The libcoap html documentation will be build without DOT graphics!])
                HAVE_DOT="NO"
                USE_CALL_GRAPH="NO"
            else
                AC_MSG_CHECKING([for compatible dot version (>= $dot_version_required)])
                case $host in
                    *-freebsd1*)
                    # csh and tcsh have a different output redirection than more recent shells
                    # cmd >& file   # Redirect both stdout and stderr to file.
                    # cmd >>& file  # Append both stdout and stderr to file.
                    # cmd1 | cmd2   # pipe stdout to cmd2
                    # cmd1 |& cmd2  # pipe stdout and stderr to cmd2
                    # Using an explicit call with the default always available C-shell on FreeBSD,
                    # the user may have installed another shell from a port which we don't know here
                    dot_version=`export DOT=$DOT && csh -c '$DOT -V |& cut -f5 -d" "'`
                    ;;

                    *)
                    dot_version=`$DOT -V 2>&1 | cut -f5 -d" "`
                    ;;

                esac
                AS_VERSION_COMPARE([$dot_version],
                                   [$dot_version_required],
                                   [AC_MSG_RESULT([no])
                                    DOT=""],
                                   [AC_MSG_RESULT([yes $dot_version])],
                                   [AC_MSG_RESULT([yes $dot_version])])
                if test "x$DOT" = "x" -a "x$build_doxygen" = "xyes"; then
                    AC_MSG_WARN([==> Graphviz dot $dot_version too old. Graphviz >= $dot_version_required required for doxygen build.])
                    AC_MSG_ERROR([==> Install required graphviz version or disable the doxygen documentation using '--disable-doxygen'.])
                fi
                # we found dot and the version is valid
                HAVE_DOT="YES"
                # let doxygen create caller graphics
                # see http://www.stack.nl/~dimitri/doxygen/manual/config.html#cfg_call_graph
                USE_CALL_GRAPH="YES"
                # exporting the tests to doc/Doxygen(.in)
                AC_SUBST(HAVE_DOT)
                AC_SUBST(USE_CALL_GRAPH)
            fi
        fi
    fi
fi
AM_CONDITIONAL(BUILD_DOXYGEN, [test "x$build_doxygen" = "xyes"])

AM_CONDITIONAL([HAVE_DOXYGEN], [test -n "$DOXYGEN"])
AM_COND_IF([HAVE_DOXYGEN], [AC_CONFIG_FILES([doc/Doxyfile])])

# __manpages__

AC_ARG_ENABLE([manpages],
              [AS_HELP_STRING([--enable-manpages],
                              [Enable building the manpages [default=yes]])],
              [build_manpages="$enableval"],
              [build_manpages="yes"])

if test -z "$enable_manpages"; then
    if test "x$enable_documentation" = "xno"; then
        build_manpages="no"
    fi
fi

if test "x$build_manpages" = "xyes"; then
    AC_ARG_VAR([A2X], [a2x command])
    AC_PATH_PROG([A2X], [a2x])
    if test "x$A2X" = "x"; then
        AC_MSG_WARN([==> You want to build the manpages, but a2x was not found!])
        AC_MSG_ERROR([==> Install the package that contains a2x (mostly asciidoc) or disable the build of the manpages using '--disable-manpages'.])
        build_manpages="no"
    else
        AX_CHECK_A2X_TO_MANPAGE([], [
            AC_MSG_RESULT([no])
            AC_MSG_WARN([==> You want to build the manpages with a2x, but manpage formatting does not work!])
            AC_MSG_ERROR([==> Install the packages that contains the docbook DTD and XSL stylesheets (presumably docbook, docbook-xml) or disable the build of the manpages using '--disable-manpages'.])
            build_manpages="no"
        ])
    fi
fi
AM_CONDITIONAL(BUILD_MANPAGES, [test "x$build_manpages" = "xyes"])

# configure options
# __dtls__
# The Datagram Transport Layer Security (DTLS) feature needs cryptography
# functions.
# We currently support the GnuTLS and OpenSSL library. The user can preselect
# the cryptography library that should be used by adding '--with-gnutls' or
# '--with-openssl'.
# If the user isn't using a selection we first search for GnuTLS and fallback
# to OpenSSL if the GnuTLS library couldn't be found.

gnutls_version_required=3.3.0
openssl_version_required=1.1.0
mbedtls_version_required=2.7.10

AC_ARG_ENABLE([dtls],
              [AS_HELP_STRING([--enable-dtls],
                              [Enable building with DTLS support [default=yes]])],
              [build_dtls="$enableval"],
              [build_dtls="yes"])

AC_ARG_WITH([gnutls],
            [AS_HELP_STRING([--with-gnutls],
                            [Use GnuTLS for DTLS functions])],
            [with_gnutls="$withval"],
            [with_gnutls="no"])

AC_ARG_WITH([openssl],
            [AS_HELP_STRING([--with-openssl],
                            [Use OpenSSL for DTLS functions])],
            [with_openssl="$withval"],
            [with_openssl="no"])

AC_ARG_WITH([mbedtls],
            [AS_HELP_STRING([--with-mbedtls],
                            [Use mbed TLS for DTLS functions])],
            [with_mbedtls="$withval"],
            [with_mbedtls="no"])

AC_ARG_WITH([tinydtls],
           [AS_HELP_STRING([--with-tinydtls],
                           [Use TinyDTLS for DTLS functions])],
           [with_tinydtls="$withval"],
           [with_tinydtls="no"])

if test "x$with_gnutls" = "xyes" -o "x$with_openssl" = "xyes" -o "x$with_mbedtls" = "xyes" -o "x$with_tinydtls" = "xyes"; then
    if test "x$build_dtls" = "x"; then
        # Give an advice that '--with_gnutls', '--with_openssl', '--with-mbedtls' or '--with-tinydtls' was used but
        # DTLS support isn't configured.
        AC_MSG_NOTICE([==> Using the configure options '--with-gnutls', '--with-openssl', '--with-mbedtls' or '--with-tinydtls' without '--enable-dtls' is useles and will be ignored.])
    fi
fi

# O.K. the user hasn't de-selected DTLS
if test "x$build_dtls" = "xyes"; then
    # The user can't select multiple crypto libraries.
    TLSCOUNT=0
    if test "x$with_gnutls" = "xyes"; then
        TLSCOUNT=`expr $TLSCOUNT + 1`
    fi
    if test "x$with_openssl" = "xyes"; then
        TLSCOUNT=`expr $TLSCOUNT + 1`
    fi
    if test "x$with_mbedtls" = "xyes"; then
        TLSCOUNT=`expr $TLSCOUNT + 1`
    fi
    if test "x$with_tinydtls" = "xyes"; then
        TLSCOUNT=`expr $TLSCOUNT + 1`
    fi
    if test "$TLSCOUNT" -gt 1; then
        AC_MSG_ERROR([==> You can't use more than 1 of the options '--with-gnutls', '--with-openssl', '--with-mbedtls' or '--with-tinydtls' at the same time while '--enable-dtls' is selected!
                  ==> Please note, the option '--enable-dtls' is turned on by default if not explicitly disabled!])
    fi

    # Check for all possible usable and supported SSL crypto libraries
    # GnuTLS
    PKG_CHECK_MODULES([GnuTLS],
                      [gnutls],
                      [have_gnutls="yes"],
                      [have_gnutls="no"])

    # OpenSSL
    PKG_CHECK_MODULES([OpenSSL],
                      [openssl],
                      [have_openssl="yes"],
                      [have_openssl="no"])

    # mbed TLS [does not have mbedtls.pc pkg-config file]
    AC_CHECK_LIB(mbedtls, mbedtls_ssl_handshake,
                 [have_mbedtls="yes"; MbedTLS_CFLAGS="" ; MbedTLS_LIBS="-lmbedtls -lmbedcrypto -lmbedx509"],
                 [have_mbedtls="no"])

    # TinyDTLS ?
    # TBD ?

    # The user wants to use explicit GnuTLS if '--with-gnutls' was set.
    if test "x$with_gnutls" = "xyes"; then
        # Some more sanity checking.
        if test "x$have_gnutls" != "xyes"; then
            AC_MSG_ERROR([==> You want to build libcoap with DTLS support by the GnuTLS library but pkg-config file 'gnutls.pc' could not be found!
                      Install the package(s) that contains the development files for GnuTLS,
                      or select a different TLS library or disable the DTLS support using '--disable-dtls'.])
        fi
        AC_MSG_NOTICE([The use of GnuTLS was explicitly requested with configure option '--with-gnutls'!])

        # check for valid GnuTLS version
        gnutls_version=`pkg-config --modversion gnutls`
        AX_CHECK_GNUTLS_VERSION
        have_openssl="no" # don't confuse AC_MSG_RESULT at the end of the script
        have_mbedtls="no" # don't confuse AC_MSG_RESULT at the end of the script
        have_tinydtls="no" # don't confuse AC_MSG_RESULT at the end of the script
    fi

    # The user wants to use explicit OpenSSL if '--with-openssl was set'.
    if test "x$with_openssl" = "xyes"; then
        # Some more sanity checking.
        if test "x$have_openssl" != "xyes"; then
            AC_MSG_ERROR([==> You want to build libcoap with DTLS support by the OpenSSL library but pkg-config file 'openssl.pc' could not be found!
                      Install the package(s) that contains the development files for OpenSSL,
                      or select a different TLS library or disable the DTLS support using '--disable-dtls'.])
        fi
        AC_MSG_NOTICE([The use of OpenSSL was explicitly requested with configure option '--with-openssl'!])

        # check for valid OpenSSL version
        openssl_version=`pkg-config --modversion openssl`
        AX_CHECK_OPENSSL_VERSION
        have_gnutls="no" # don't confuse AC_MSG_RESULT at the end of the script
        have_mbedtls="no" # don't confuse AC_MSG_RESULT at the end of the script
        have_tinydtls="no" # don't confuse AC_MSG_RESULT at the end of the script
    fi

    # The user wants to use explicit mbed TLS if '--with-mbedtls was set'.
    if test "x$with_mbedtls" = "xyes"; then
        # Some more sanity checking.
        if test "x$have_mbedtls" != "xyes"; then
            AC_MSG_ERROR([==> You want to build libcoap with DTLS support by the mbed TLS library but library 'mbedtls' could not be found!
                      Install the package(s) that contains the development files for mbed TLS,
                      or select a different TLS library or disable the DTLS support using '--disable-dtls'.])
        fi
        AC_MSG_NOTICE([The use of mbed TLS was explicitly requested with configure option '--with-mbedtls'!])

        # check for valid mbed TLS version (mbedtls.pc does not exist - hmm)
        # mbedtls_version=`pkg-config --modversion mbedtls`
        # AX_CHECK_MBEDTLS_VERSION
        have_gnutls="no" # don't confuse AC_MSG_RESULT at the end of the script
        have_openssl="no" # don't confuse AC_MSG_RESULT at the end of the script
        have_tinydtls="no" # don't confuse AC_MSG_RESULT at the end of the script
    fi

    # The user wants to use explicit TinyDTLS if '--with-tinydtls was set'.
    if test "x$with_tinydtls" = "xyes" ; then
        if test -d "$srcdir/ext/tinydtls"; then
           AC_CONFIG_SUBDIRS([ext/tinydtls])
           have_tinydtls="yes"
         else
           have_tinydtls="no" # don't confuse AC_MSG_RESULT at the end of the script
         fi
         have_gnutls="no" # don't confuse AC_MSG_RESULT at the end of the script
         have_openssl="no" # don't confuse AC_MSG_RESULT at the end of the script
         have_mbedtls="no" # don't confuse AC_MSG_RESULT at the end of the script
    fi

    if test "$TLSCOUNT" -eq 0; then
      # The user hasn't requested the use of a specific cryptography library
      # we try first GnuTLS for usability ...
      if test "x$have_gnutls" = "xyes"; then
          gnutls_version=`pkg-config --modversion gnutls`
          AX_CHECK_GNUTLS_VERSION
          AC_MSG_NOTICE([Using auto selected library GnuTLS for DTLS support!])
          with_gnutls_auto="yes"
          have_openssl="no" # don't confuse AC_MSG_RESULT at the end of the script
          have_mbedtls="no" # don't confuse AC_MSG_RESULT at the end of the script
          have_tinydtls="no" # don't confuse AC_MSG_RESULT at the end of the script

      # ... and if not found check OpenSSL is suitable.
      elif test "x$have_openssl" = "xyes"; then
          openssl_version=`pkg-config --modversion openssl`
          AX_CHECK_OPENSSL_VERSION
          AC_MSG_NOTICE([Using auto selected library OpenSSL for DTLS support!])
          with_openssl_auto="yes"
          have_gnutls="no" # don't confuse AC_MSG_RESULT at the end of the script
          have_mbedtls="no" # don't confuse AC_MSG_RESULT at the end of the script
          have_tinydtls="no" # don't confuse AC_MSG_RESULT at the end of the script

      # ... and if not found check mbed TLS is suitable.
      elif test "x$have_mbedtls" = "xyes"; then
          # mbed TLS [does not have mbedtls.pc pkg-config file]
          # mbedtls_version=`pkg-config --modversion mbedtls`
          # AX_CHECK_MBEDTLS_VERSION
          AC_MSG_NOTICE([Using auto selected library mbed TLS for DTLS support!])
          with_mbedtls_auto="yes"
          have_gnutls="no" # don't confuse AC_MSG_RESULT at the end of the script
          have_openssl="no" # don't confuse AC_MSG_RESULT at the end of the script
          have_tinydtls="no" # don't confuse AC_MSG_RESULT at the end of the script

      # Note that tinyDTLS is used only when explicitly requested.
      # Giving out an error message if we haven't found at least one crypto library.
      else
          AC_MSG_ERROR([==> Option '--enable-dtls' is set but none of the needed cryptography libraries GnuTLS, OpenSSL or mbed TLS could be found!
                        Install at least one of the package(s) that contains the development files for GnuTLS (>= $gnutls_version_required), OpenSSL(>= $openssl_version_required), or mbed TLS(>= $mbedtls_version_required)
                        or disable the DTLS support using '--disable-dtls'.])
      fi
    fi

    # Saving the DTLS related Compiler flags.
    if test "x$with_gnutls" = "xyes" -o "x$with_gnutls_auto" = "xyes"; then
        DTLS_CFLAGS="$GnuTLS_CFLAGS"
        DTLS_LIBS="$GnuTLS_LIBS"
        AC_DEFINE(HAVE_LIBGNUTLS, [1], [Define if the system has libgnutls28])
    fi
    if test "x$with_openssl" = "xyes" -o "x$with_openssl_auto" = "xyes"; then
        DTLS_CFLAGS="$OpenSSL_CFLAGS"
        DTLS_LIBS="$OpenSSL_LIBS"
        AC_DEFINE(HAVE_OPENSSL, [1], [Define if the system has libssl1.1])
    fi
    if test "x$with_mbedtls" = "xyes" -o "x$with_mbedtls_auto" = "xyes"; then
        DTLS_CFLAGS="$MbedTLS_CFLAGS"
        DTLS_LIBS="$MbedTLS_LIBS"
        AC_DEFINE(HAVE_MBEDTLS, [1], [Define if the system has libmbedtls2.7.10])
    fi
    if test "x$with_tinydtls" = "xyes"; then
        DTLS_CFLAGS="-I \$(top_srcdir)/ext/tinydtls"
        if test "x$enable_shared" = "xyes"; then
            DTLS_LIBS="-L\$(top_builddir)/ext/tinydtls -ltinydtls"
        else
            # Needed as TinyDTLS compiling does not recognize --disable-shared
            # and still builds libtinydtls.so which gets linked in otherwise
            DTLS_LIBS="-L\$(top_builddir)/ext/tinydtls -l:libtinydtls.a"
        fi
        AC_DEFINE(HAVE_LIBTINYDTLS, [1], [Define if the system has libtinydtls])
    fi
    AC_SUBST(DTLS_CFLAGS)
    AC_SUBST(DTLS_LIBS)
fi

# Define the Library name extension for the TLS the library was linked against
if test "x$with_openssl" = "xyes" -o "x$with_openssl_auto" = "xyes"; then
    LIBCOAP_DTLS_LIB_EXTENSION_NAME=-openssl
elif test "x$with_gnutls" = "xyes" -o "x$with_gnutls_auto" = "xyes"; then
    LIBCOAP_DTLS_LIB_EXTENSION_NAME=-gnutls
elif test "x$with_mbedtls" = "xyes" -o "x$with_mbedtls_auto" = "xyes"; then
    LIBCOAP_DTLS_LIB_EXTENSION_NAME=-mbedtls
elif test "x$with_tinydtls" = "xyes"; then
    LIBCOAP_DTLS_LIB_EXTENSION_NAME=-tinydtls
else
    LIBCOAP_DTLS_LIB_EXTENSION_NAME=
fi

if test "x$LIBCOAP_DTLS_LIB_EXTENSION_NAME" != "x"; then
    LIBCOAP_NAME_SUFFIX="$LIBCOAP_API_VERSION$LIBCOAP_DTLS_LIB_EXTENSION_NAME"
else
    LIBCOAP_NAME_SUFFIX="$LIBCOAP_API_VERSION"
fi

AC_SUBST(LIBCOAP_NAME_SUFFIX)
AC_SUBST(LIBCOAP_DTLS_LIB_EXTENSION_NAME)
AC_SUBST([DOLLAR_SIGN],[$])

# configure options
# __tests__
AC_ARG_ENABLE([tests],
              [AS_HELP_STRING([--enable-tests],
                              [Enable building the binary testsuite. Requires --enable-static  [default=no]])],
              [build_tests="$enableval"],
              [build_tests="no"])

if test "x$build_tests" = "xyes"; then
    PKG_CHECK_MODULES([CUNIT],
                      [cunit],
                      [have_cunit=yes
                       AC_DEFINE(HAVE_LIBCUNIT, [1], [Define if the system has libcunit])],
                      [have_cunit=no
                       AC_MSG_WARN([==> You want to build the testing binary but the pkg-config file cunit.pc could not be found or installed CUnit version is too old!])
                       AC_MSG_ERROR([==> Install the package(s) that contains the development files for CUnit or disable the testing binary using '--disable-tests'.])
                      ])
    if test "x$enable_static" = "xno"; then
        enable_static=yes
        AC_MSG_WARN([--enable-tests requires --enable-static which is now enabled.])
    fi
fi
AM_CONDITIONAL(HAVE_CUNIT, [test "x$CUNIT_LIBS" != "x"])

# configure options
# __examples__
AC_ARG_ENABLE([examples],
              [AS_HELP_STRING([--enable-examples],
                              [Enable building the example binaries [default=yes]])],
              [build_examples="$enableval"],
              [build_examples="yes"])

AM_CONDITIONAL(BUILD_EXAMPLES, [test "x$build_examples" = "xyes"])

# configure options
# __gcov__
AC_ARG_ENABLE([gcov],
              [AS_HELP_STRING([--enable-gcov],
                              [Enable building with gcov test coverage support [default=no]])],
              [build_gcov="$enableval"],
              [build_gcov="no"
               AC_MSG_WARN([gcov is disabled])
              ])

if test "x$build_gcov" = "xyes"; then
   if test "x$GCC" != "xyes"; then
        AC_MSG_ERROR([Currently, gcov is assumed to work with GCC-compatible compilers only.])
   else
        AX_CHECK_COMPILE_FLAG([-fprofile-arcs], [CFLAGS="$CFLAGS -fprofile-arcs"])
        AX_CHECK_COMPILE_FLAG([-ftest-coverage], [CFLAGS="$CFLAGS -ftest-coverage"])
        # FIXME: clang complains about '--coverage'
        AX_CHECK_COMPILE_FLAG([--coverage], [CFLAGS="$CFLAGS --coverage -O0" LDFLAGS="$LDFLAGS --coverage"])
   fi
fi

# configure options
# __tcp__
AC_ARG_ENABLE([tcp],
              [AS_HELP_STRING([--enable-tcp],
                              [Enable building with TCP support [default=yes]])],
              [build_tcp="$enableval"],
              [build_tcp="yes"])

AC_DEFINE(COAP_DISABLE_TCP, [0], [Define to 1 to build without TCP support.])
AS_IF([test "x$build_tcp" != "xyes"], [AC_DEFINE(COAP_DISABLE_TCP, [1])])
AC_SUBST(COAP_DISABLE_TCP)

# end configure options
#######################

###########################################
# from configure options independent checks

# Check for (ex)ctags binary
# The needed ctags binary name differs on FreeBSD and Linux, on Linux
# systems we search for 'ctags', on FreeBSD for 'exctags'
case $host in
    # FreeBSD has exctags from the ctags port
    *-freebsd1*)
    AC_ARG_VAR([CTAGS_PROG],[the 'exctags' program to use for make target 'update-map-file'])
    AC_PATH_PROG([CTAGS_PROG],[exctags])
    ;;

    *)
    # Linux distributions have exuberant-ctags
    AC_ARG_VAR([CTAGS_PROG],[the 'ctags' program to use for make target 'update-map-file'])
    AC_PATH_PROG([CTAGS_PROG],[ctags])
    ;;

esac

if test "x$CTAGS_PROG" = "x"; then
    AC_MSG_NOTICE([==> Note: '(ex)ctags' command not found!])
    AC_MSG_WARN([==> Without ctags you will be unable to run the target 'update-map-file'!])
    AC_MSG_WARN([==> This is no problem if you just want to build the library libcoap.])
else
    if test "`$CTAGS_PROG --help | grep '\--<LANG>-kinds'`" = ""; then
        AC_MSG_NOTICE([==> Note: Your ctags binary does not support '--c-kinds'!])
        AC_MSG_NOTICE([==> Most likely, you are using the GNU Emacs ctag and not exuberant ctag.])
        AC_MSG_WARN([==> This option is required for the target 'update-map-file'.])
        AC_MSG_WARN([==> which is not a problem if you just want to build the library libcoap.])
    fi
fi

# Checks for header files.
AC_CHECK_HEADERS([assert.h arpa/inet.h limits.h netdb.h netinet/in.h \
                  pthread.h \
                  stdlib.h string.h strings.h sys/socket.h sys/time.h \
                  time.h unistd.h sys/unistd.h syslog.h sys/ioctl.h])

# For epoll, need two headers (sys/epoll.h sys/timerfd.h), but set up one #define
AC_CHECK_HEADER([sys/epoll.h])
AC_CHECK_HEADER([sys/timerfd.h])
if test "x$ac_cv_header_sys_epoll_h" = "xyes" -a "x$ac_cv_header_sys_timerfd_h" = "xyes"; then
    have_epoll="yes"
    AC_ARG_WITH([epoll],
            [AS_HELP_STRING([--with-epoll],
                            [Use epoll for I/O handling [if O/S supports it]])],
            [with_epoll="$withval"],
            [with_epoll="yes"])
else
    have_epoll="no"
    if test "x$with_epoll" = "xyes"; then
        AC_MSG_WARN([==> Underlying O/S does not support epoll - --with-epoll ignored.])
        with_epoll="no"
    fi
fi

if test "x$with_epoll" = "xyes"; then
    AC_DEFINE(COAP_EPOLL_SUPPORT, 1, [Define if the system has epoll support])
fi

AC_ARG_ENABLE([small-stack],
        [AS_HELP_STRING([--enable-small-stack],
                        [Use small-stack if the available stack space is restricted [default=no]])],
        [enable_small_stack="$enableval"],
        [enable_small_stack="no"])

if test "x$enable_small_stack" = "xyes"; then
    AC_DEFINE(COAP_CONSTRAINED_STACK, 1, [Define if the system has small stack size])
fi

# Checks for typedefs, structures, and compiler characteristics.
AC_TYPE_SIZE_T
AC_TYPE_SSIZE_T

# Checks for library functions.
AC_CHECK_FUNCS([memset select socket strcasecmp strrchr getaddrinfo \
                strnlen malloc pthread_mutex_lock getrandom])

# Check if -lsocket -lnsl is required (specifically Solaris)
AC_SEARCH_LIBS([socket], [socket])
AC_SEARCH_LIBS([inet_ntop], [nsl])

# Check if clock_gettime() requires librt, when available
AC_SEARCH_LIBS([clock_gettime], [rt])

#check for struct cmsghdr
AC_CHECK_TYPES([struct cmsghdr],,,[
AC_INCLUDES_DEFAULT
#include <sys/socket.h>])

AC_MSG_CHECKING([operating system])

# Set up here some extra platform depended defines and variables.
# The "ADDITIONAL_CFLAGS" is need as this stand-alone definition
# for the doxygen part.
case $host in
    *-linux* | *-uclinux*)
    AC_MSG_RESULT([Linux])
    ADDITIONAL_CFLAGS="-D_GNU_SOURCE"

    # Not yet needed but if some code definitions have to depend on the platform.
    #AC_DEFINE(OS_LINUX, 1, [Linux backend])
    #AC_SUBST(OS_LINUX)
    ;;

    *-cygwin*)
    AC_MSG_RESULT([Cygwin])
    ADDITIONAL_CFLAGS="-D_GNU_SOURCE -D_CYGWIN_ENV"
    LDFLAGS="-no-undefined $LDFLAGS"
    ;;

    *-solaris*)
    AC_MSG_RESULT([Solaris])
    # set _XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED to enable XPG4v2 (POSIX 2004)
    # set __EXTENSION__ to shut up feature test macros that restrict -std=c99
    # to only C99 (and nothing newer)
    ADDITIONAL_CFLAGS="-D_XOPEN_SOURCE=600 -D_XOPEN_SOURCE_EXTENDED=600 -D__EXTENSIONS__=1"
    ;;

    *-darwin*)
    AC_MSG_RESULT([Darwin])
    ADDITIONAL_CFLAGS="-D_GNU_SOURCE"

    AC_DEFINE(__APPLE_USE_RFC_3542, 1, [Define this to 1 for ancillary data on MacOS])

    # Not yet needed but if some code definitions have to depend on the platform.
    #AC_DEFINE(OS_MACOS, 1, [MacOS backend])
    #AC_SUBST(OS_MACOS)
    ;;

    *-freebsd1*)
    AC_MSG_RESULT([FreeBSD-1x])
    ADDITIONAL_CFLAGS="-D_GNU_SOURCE"
    ;;

    *kfreebsd*)
    AC_MSG_RESULT([kFreeBSD])
    ADDITIONAL_CFLAGS="-D_GNU_SOURCE"
    ;;

    *)
    AC_MSG_WARN([==> Currently unsupported operating system '${host}' !])
    AC_MSG_ERROR([==> If you can provide patches to support your operating system please write to 'libcoap-developers@lists.sourceforge.net'.])
esac

# Exporting the PREDEFINED_CFLAGS definition
PREDEFINED_CFLAGS=`echo $ADDITIONAL_CFLAGS | $SED -e 's/-D//g'`
AC_SUBST(PREDEFINED_CFLAGS)

# And finally combining the CFLAGS together ...
CFLAGS="$CFLAGS $ADDITIONAL_CFLAGS"

# Override the various template files, currently just makefiles and the
# pkgconfig *.pc file.
# Later if the API version is changing don't forget to change the
# libcoap-$LIBCOAP_API_VERSION.pc.in file too!! You will have to change
# the 'Cflags' variable to something like
#     Cflags: -I${includedir}/coap-@LIBCOAP_API_VERSION@
#
AC_CONFIG_FILES([
Makefile
doc/Makefile
examples/Makefile
include/coap2/coap.h
man/coap.txt
man/coap_attribute.txt
man/coap_cache.txt
man/coap_context.txt
man/coap_encryption.txt
man/coap_handler.txt
man/coap_io.txt
man/coap_keepalive.txt
man/coap_logging.txt
man/coap_observe.txt
man/coap_pdu_setup.txt
man/coap_recovery.txt
man/coap_resource.txt
man/coap_session.txt
man/coap_string.txt
man/coap_tls_library.txt
man/coap-client.txt
man/coap-server.txt
man/coap-rd.txt
man/Makefile
tests/Makefile
tests/oss-fuzz/Makefile.ci
libcoap-$LIBCOAP_NAME_SUFFIX.pc:libcoap-$LIBCOAP_API_VERSION.pc.in
])

AC_OUTPUT

AC_MSG_RESULT([
libcoap configuration summary:
      libcoap package version : "$PACKAGE_VERSION"
      libcoap library version : "$LIBCOAP_SO_VERSION"
      libcoap API version     : "$LIBCOAP_API_VERSION"
      libcoap DTLS lib extn   : "$LIBCOAP_DTLS_LIB_EXTENSION_NAME"
      host system             : "$host"]);
if test "x$build_tcp" != "xno"; then
    AC_MSG_RESULT([      build with TCP support  : "yes"])
else
    AC_MSG_RESULT([      build with TCP support  : "no"])
fi
if test "x$with_gnutls" = "xyes" -o "x$with_gnutls_auto" = "xyes"; then
    AC_MSG_RESULT([      build DTLS support      : "yes"])
    AC_MSG_RESULT([          -->  GnuTLS around  : "yes" (found GnuTLS $gnutls_version)])
    AC_MSG_RESULT([               GNUTLS_CFLAGS  : "$GnuTLS_CFLAGS"])
    AC_MSG_RESULT([               GNUTLS_LIBS    : "$GnuTLS_LIBS"])
fi
if test "x$with_openssl" = "xyes" -o "x$with_openssl_auto" = "xyes"; then
    AC_MSG_RESULT([      build DTLS support      : "yes"])
    AC_MSG_RESULT([         -->  OpenSSL around  : "yes" (found OpenSSL $openssl_version)])
    AC_MSG_RESULT([              OPENSSL_CFLAGS  : "$OpenSSL_CFLAGS"])
    AC_MSG_RESULT([              OPENSSL_LIBS    : "$OpenSSL_LIBS"])
fi
if test "x$with_mbedtls" = "xyes" -o "x$with_mbedtls_auto" = "xyes"; then
    AC_MSG_RESULT([      build DTLS support      : "yes"])
    # mbed TLS [does not have mbedtls.pc pkg-config file, hence no mbedtls_version]
    AC_MSG_RESULT([         -->  mbed TLS around : "yes" (found mbed TLS)])
    AC_MSG_RESULT([              MBEDTLS_CFLAGS  : "$MbedTLS_CFLAGS"])
    AC_MSG_RESULT([              MBEDTLS_LIBS    : "$MbedTLS_LIBS"])
fi
if test "x$with_tinydtls" = "xyes"; then
    AC_MSG_RESULT([      build DTLS support      : "yes"])
    AC_MSG_RESULT([         -->  tinyDTLS around : "yes"])
    AC_MSG_RESULT([              TINYDTLS_CFLAGS : "$DTLS_CFLAGS"])
    AC_MSG_RESULT([              TINYDTLS_LIBS   : "$DTLS_LIBS"])
fi
if test "x$build_dtls" != "xyes"; then
    AC_MSG_RESULT([      build DTLS support      : "no"])
fi
if test "x$have_epoll" = "xyes"; then
    AC_MSG_RESULT([      build using epoll       : "$with_epoll"])
fi
AC_MSG_RESULT([      enable small stack size : "$enable_small_stack"])
if test "x$build_doxygen" = "xyes"; then
    AC_MSG_RESULT([      build doxygen pages     : "yes"])
    AC_MSG_RESULT([          --> Doxygen around  : "yes" ($DOXYGEN $doxygen_version)])
    if test "x$DOT" = "x"; then
        AC_MSG_RESULT([             -->  dot around  : "no" (DOT not found!)])
    else
        AC_MSG_RESULT([             -->  dot around  : "yes" ($DOT $dot_version)])
    fi
else
    if test "x$build_doxygen" = "xno"; then
        AC_MSG_RESULT([      build doxygen pages     : "no"])
    fi
fi
if test "x$build_manpages" = "xyes"; then
    AC_MSG_RESULT([      build man pages         : "yes"])
else
    AC_MSG_RESULT([      build man pages         : "no"])
fi
if test "x$build_tests" = "xyes"; then
    AC_MSG_RESULT([      build unit test binary  : "yes"])
else
    AC_MSG_RESULT([      build unit test binary  : "no"])
fi
if test "x$build_examples" = "xyes"; then
    AC_MSG_RESULT([      build examples          : "yes"])
else
    AC_MSG_RESULT([      build examples          : "no"])
fi
if test "x$build_gcov" = "xyes"; then
    AC_MSG_RESULT([      build with gcov support : "yes"])
else
    AC_MSG_RESULT([      build with gcov support : "no"])
fi
if test "x$enable_shared" = "xyes"; then
    AC_MSG_RESULT([      build shared library    : "yes"])
else
    AC_MSG_RESULT([      build shared library    : "no"])
fi
if test "x$enable_static" = "xyes"; then
    AC_MSG_RESULT([      build static library    : "yes"])
else
    AC_MSG_RESULT([      build static library    : "no"])
fi