configure.in - platform/external/libsrtp2 - Gitiles

 dnl Process this file with autoconf to produce a configure script.
 AC_INIT([libsrtp2], [2.1.0-pre], [https://github.com/cisco/libsrtp/issues])

 dnl Must come before AC_PROG_CC
 EMPTY_CFLAGS="no"
 if test "x$CFLAGS" = "x"; then
    dnl Default value for CFLAGS if not specified.
    EMPTY_CFLAGS="yes"
 fi

 dnl Checks for programs.
 m4_ifdef([AM_PROG_AR], [AM_PROG_AR])
 AC_PROG_RANLIB
 AC_PROG_CC
 AC_PROG_INSTALL
 AC_PROG_SED

 dnl Check the byte order
 AC_C_BIGENDIAN

 AC_CANONICAL_HOST

 dnl check host_cpu type, set defines appropriately
 case $host_cpu in
   i*86 | x86_64 )
     AC_DEFINE([CPU_CISC], [1], [Define if building for a CISC machine (e.g. Intel).])
     AC_DEFINE([HAVE_X86], [1], [Define to use X86 inlined assembly code])
     ;;
   * )
     AC_DEFINE([CPU_RISC], [1], [Define if building for a RISC machine (assume slow byte access).])
     ;;
 esac

 dnl Check if we are on a Windows platform.
 case $host_os in
   *cygwin*|*mingw* )
     EXE=.exe
     ;;
   * )
     EXE=""
     ;;
 esac
 AC_SUBST([EXE])   # define executable suffix; this is needed for `make clean'

 dnl Checks for supported compiler flags.
 supported_cflags=""
 if test "$EMPTY_CFLAGS" = "no"; then
   supported_cflags="$CFLAGS"
 fi

 dnl For accurate detection, we need warnings as errors.
 dnl I.e. Clang will issue a warning about unsupported flags.
 dnl For the compilation to fail, those warnings needs to be upgraded to errors.
 dnl This will be removed again once the tests are complete (see below).
 WERROR=""
 for w in -Werror -errwarn; do
   if test "x$WERROR" = "x"; then
     AC_MSG_CHECKING([whether the compiler supports $w])
     save_cflags="$CFLAGS"
     AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$w"], [CFLAGS="$CFLAGS $w"])
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
       [WERROR="$w"
        AC_MSG_RESULT([yes])],
       [CFLAGS="$save_cflags"
        AC_MSG_RESULT([no])])
   fi
 done

 dnl Note that -fPIC is also added to LDFLAGS.
 AC_MSG_CHECKING([whether the compiler supports -fPIC])
 save_cflags="$CFLAGS"
 AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="-fPIC"], [CFLAGS="$CFLAGS -fPIC"])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
   [AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="-fPIC"], [supported_cflags="$supported_cflags -fPIC"])
    AS_IF([test "x$LDFLAGS" = "x"], [LDFLAGS="-fPIC"], [LDFLAGS="$LDFLAGS -fPIC"])
    AC_MSG_RESULT([yes])],
   [CFLAGS="$save_cflags"
    AC_MSG_RESULT([no])])

 if test "$EMPTY_CFLAGS" = "yes"; then
   for f in -Wall -pedantic; do
     AC_MSG_CHECKING([whether the compiler supports $f])
     save_cflags="$CFLAGS"
     AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$f"], [CFLAGS="$CFLAGS $f"])
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
       [AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="$f"], [supported_cflags="$supported_cflags $f"])
        AC_MSG_RESULT([yes])],
       [CFLAGS="$save_cflags"
        AC_MSG_RESULT([no])])
   done

   OOPT=""
   for f in -O4 -O3; do
     if test "x$OOPT" = "x"; then
       AC_MSG_CHECKING([whether the compiler supports $f])
       save_cflags="$CFLAGS"
       AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$f"], [CFLAGS="$CFLAGS $f"])
       AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
         [AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="$f"], [supported_cflags="$supported_cflags $f"])
          OOPT="$f"
          AC_MSG_RESULT([yes])],
         [CFLAGS="$save_cflags"
          AC_MSG_RESULT([no])])
     fi
   done

   for f in -fexpensive-optimizations -funroll-loops; do
     AC_MSG_CHECKING([whether the compiler supports $f])
     save_cflags="$CFLAGS"
     AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$f"], [CFLAGS="$CFLAGS $f"])
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
       [AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="$f"], [supported_cflags="$supported_cflags $f"])
        AC_MSG_RESULT([yes])],
       [CFLAGS="$save_cflags"
        AC_MSG_RESULT([no])])
   done
 fi

 dnl When turning off warnigns, we're expecting unrecognized command line option errors if they're not
 dnl supported. However, the -Wno-<warning> form isn't consulted unless a warning is triggered.
 dnl At least that's the case for GCC. So to check which warnings we can turn off, we dnl need to check
 dnl if they can be turned on, thereby forcing GCC to take the argument into account right away.
 for f in -Wno-language-extension-token; do
   AC_MSG_CHECKING([whether the compiler supports $f])
   save_cflags="$CFLAGS"
   testf=$(echo "$f" | $SED 's|-Wno-\(.*\)|-W\1|g')
   AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$testf"], [CFLAGS="$CFLAGS $testf"])
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
     [AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="$f"], [supported_cflags="$supported_cflags $f"])
      AC_MSG_RESULT([yes])],
     [CFLAGS="$save_cflags"
      AC_MSG_RESULT([no])])
 done

 dnl Remowing -Werror again
 CFLAGS="$supported_cflags"

 dnl Checks for header files.
 AC_HEADER_STDC
 AC_CHECK_HEADERS(
     [unistd.h byteswap.h stdint.h sys/uio.h inttypes.h sys/types.h machine/types.h sys/int_types.h],
     [], [], [AC_INCLUDES_DEFAULT])

 dnl socket() and friends
 AC_CHECK_HEADERS([sys/socket.h netinet/in.h arpa/inet.h], [], [], [AC_INCLUDES_DEFAULT])
 AC_CHECK_HEADERS(
     [windows.h],
     [AC_CHECK_HEADERS([winsock2.h], [], [], [AC_INCLUDES_DEFAULT])],
     [], [AC_INCLUDES_DEFAULT])

 AC_CHECK_TYPES([int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, uint64_t])
 AC_CHECK_SIZEOF([unsigned long])
 AC_CHECK_SIZEOF([unsigned long long])

 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
 AC_C_INLINE
 AC_TYPE_SIZE_T

 dnl Checks for library functions.
 AC_CHECK_FUNCS([socket inet_aton usleep sigaction])

 dnl Find socket function if not found yet.
 if test "x$ac_cv_func_socket" = "xno"; then
   AC_CHECK_LIB([socket], [socket])
   AC_MSG_CHECKING([for socket in -lwsock32])
   SAVELIBS="$LIBS"
   LIBS="$LIBS -lwsock32"
   AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 #include <winsock2.h>
 ]], [[
 socket(0, 0, 0);
 ]])],[ac_cv_func_socket=yes
     AC_MSG_RESULT([yes])],[LIBS="$SAVELIBS"
     AC_MSG_RESULT([no])])
 fi

 AC_MSG_CHECKING([whether to enable debug logging in all modules])
 AC_ARG_ENABLE([debug-logging],
   [AS_HELP_STRING([--enable-debug-logging], [Enable debug logging in all modules])],
   [], enable_debug_logging=no)
 if test "$enable_debug_logging" = "yes"; then
    AC_DEFINE([ENABLE_DEBUG_LOGGING], [1], [Define to enabled debug logging for all mudules.])
 fi
 AC_MSG_RESULT([$enable_debug_logging])

 PKG_PROG_PKG_CONFIG
 AS_IF([test "x$PKG_CONFIG" != "x"], [PKG_CONFIG="$PKG_CONFIG --static"])

 AC_MSG_CHECKING([whether to leverage OpenSSL crypto])
 AC_ARG_ENABLE([openssl],
   [AS_HELP_STRING([--enable-openssl], [compile in OpenSSL crypto engine])],
   [], [enable_openssl=no])
 AC_MSG_RESULT([$enable_openssl])
 if test "$enable_openssl" = "yes"; then
    AC_MSG_CHECKING([for user specified OpenSSL directory])
    AC_ARG_WITH([openssl-dir],
       [AS_HELP_STRING([--with-openssl-dir], [Location of OpenSSL installation])],
       [if test "x$PKG_CONFIG" != "x" && test -f $with_openssl_dir/lib/pkgconfig/libcrypto.pc; then
          if test "x$PKG_CONFIG_PATH" = "x"; then
            export PKG_CONFIG_PATH="$with_openssl_dir/lib/pkgconfig"
          else
            export PKG_CONFIG_PATH="$with_openssl_dir/lib/pkgconfig:$PKG_CONFIG_PATH"
          fi
          AC_MSG_RESULT([$with_openssl_dir])
        elif test -d $with_openssl_dir/lib; then
          CFLAGS="$CFLAGS -I$with_openssl_dir/include"
          if test "x$LDFLAGS" = "x"; then
            LDFLAGS="-L$with_openssl_dir/lib"
          else
            LDFLAGS="$LDFLAGS -L$with_openssl_dir/lib"
          fi
          AC_MSG_RESULT([$with_openssl_dir])
        else
          AC_MSG_RESULT([invalid])
          AC_MSG_FAILURE([Invalid OpenSSL location: $with_openssl_dir])
        fi],
       [AC_MSG_RESULT([no])])

    if test "x$PKG_CONFIG" != "x"; then
      PKG_CHECK_MODULES([crypto], [libcrypto >= 1.0.1],
        [CFLAGS="$CFLAGS $crypto_CFLAGS"
         LIBS="$crypto_LIBS $LIBS"])
    else
      AC_CHECK_LIB([dl], [dlopen], [], [AC_MSG_WARN([can't find libdl])])
      AC_CHECK_LIB([z], [inflate], [], [AC_MSG_WARN([can't find libz])])
    fi

    AC_SEARCH_LIBS([EVP_EncryptInit], [crypto],
      [], [AC_MSG_FAILURE([can't find openssl >= 1.0.1 crypto lib])])
    AC_SEARCH_LIBS([EVP_aes_128_ctr], [crypto],
      [], [AC_MSG_FAILURE([can't find openssl >= 1.0.1 crypto lib])])
    AC_SEARCH_LIBS([EVP_aes_128_gcm], [crypto],
      [], [AC_MSG_FAILURE([can't find openssl >= 1.0.1 crypto lib])])

    AC_DEFINE([OPENSSL], [1], [Define this to use OpenSSL crypto.])
    AES_ICM_OBJS="crypto/cipher/aes_icm_ossl.o crypto/cipher/aes_gcm_ossl.o"
    HMAC_OBJS=crypto/hash/hmac_ossl.o
    AC_SUBST([USE_OPENSSL], [1])

    AC_MSG_CHECKING([whether to leverage OpenSSL KDF algorithm])
    AC_ARG_ENABLE([openssl-kdf],
       [AS_HELP_STRING([--enable-openssl-kdf], [Use OpenSSL KDF algorithm])],
       [], [enable_openssl_kdf=no])
    AC_MSG_RESULT([$enable_openssl_kdf])
    if test "$enable_openssl_kdf" = "yes"; then
      AC_SEARCH_LIBS([kdf_srtp], [crypto],
        [], [AC_MSG_FAILURE([can't find openssl KDF lib])])
      AC_DEFINE([OPENSSL_KDF], [1], [Define this to use OpenSSL KDF for SRTP.])
    fi
 else
    AES_ICM_OBJS="crypto/cipher/aes_icm.o crypto/cipher/aes.o"
    HMAC_OBJS="crypto/hash/hmac.o crypto/hash/sha1.o"
 fi
 AC_SUBST([AES_ICM_OBJS])
 AC_SUBST([HMAC_OBJS])

 dnl Checking for PCAP
 AC_CHECK_LIB([pcap], [pcap_create],
   [LIBS="-lpcap $LIBS"
    AC_DEFINE([HAVE_PCAP], [1], [Define to 1 if you have the `pcap' library (-lpcap)])
    AC_SUBST([HAVE_PCAP], [1])])

 AC_MSG_CHECKING([whether to redirect logging to stdout])
 AC_ARG_ENABLE([log-stdout],
   [AS_HELP_STRING([--enable-log-stdout], [redirecting logging to stdout])],
   [], [enable_log_stdout=no])
 if test "$enable_log_stdout" = "yes"; then
    AC_DEFINE([ERR_REPORTING_STDOUT], [1], [Define to redirect logging to stdout.])
 fi
 AC_MSG_RESULT([$enable_log_stdout])

 AC_MSG_CHECKING([wheather to use a file for logging])
 AC_ARG_WITH([log-file],
   [AS_HELP_STRING([--with-log-file], [Use file for logging])],
   [AS_CASE([x$with_log_file],
      [x], [valid_with_log_file="no"],
      [xyes], [valid_with_log_file="no"],
      [valid_with_error_file="yes"])
    AS_IF([test "$valid_with_log_file" = "no"],
      [AC_MSG_RESULT([invalid])
       AC_MSG_FAILURE([Invalid value for --with-log-file: "$with_log_file"])],
      [AC_DEFINE_UNQUOTED([ERR_REPORTING_FILE], ["$with_log_file"], [Logging statments will be writen to this file.])
       AC_MSG_RESULT([using log file: "$with_log_file"])])],
   [AC_MSG_RESULT([no])])

 AS_IF(
   [test "$enable_log_stdout" = "yes" && test "x$with_log_file" != "x"],
   [AC_MSG_FAILURE([Can only use one of --enable-log-stdout and --with-log-file; they are mutually exclusive])])

 AC_CONFIG_HEADER([crypto/include/config.h:config_in.h])

 AC_CONFIG_FILES([Makefile crypto/Makefile doc/Makefile libsrtp2.pc])
 AC_OUTPUT

 # This is needed when building outside the source dir.
 AS_MKDIR_P([crypto/cipher])
 AS_MKDIR_P([crypto/hash])
 AS_MKDIR_P([crypto/kernel])
 AS_MKDIR_P([crypto/math])
 AS_MKDIR_P([crypto/replay])
 AS_MKDIR_P([crypto/test])
 AS_MKDIR_P([doc])
 AS_MKDIR_P([srtp])
 AS_MKDIR_P([test])
	dnl Process this file with autoconf to produce a configure script.
	AC_INIT([libsrtp2], [2.1.0-pre], [https://github.com/cisco/libsrtp/issues])

	dnl Must come before AC_PROG_CC
	EMPTY_CFLAGS="no"
	if test "x$CFLAGS" = "x"; then
	dnl Default value for CFLAGS if not specified.
	EMPTY_CFLAGS="yes"
	fi

	dnl Checks for programs.
	m4_ifdef([AM_PROG_AR], [AM_PROG_AR])
	AC_PROG_RANLIB
	AC_PROG_CC
	AC_PROG_INSTALL
	AC_PROG_SED

	dnl Check the byte order
	AC_C_BIGENDIAN

	AC_CANONICAL_HOST

	dnl check host_cpu type, set defines appropriately
	case $host_cpu in
	i*86 \| x86_64 )
	AC_DEFINE([CPU_CISC], [1], [Define if building for a CISC machine (e.g. Intel).])
	AC_DEFINE([HAVE_X86], [1], [Define to use X86 inlined assembly code])
	;;
	* )
	AC_DEFINE([CPU_RISC], [1], [Define if building for a RISC machine (assume slow byte access).])
	;;
	esac

	dnl Check if we are on a Windows platform.
	case $host_os in
	cygwin\|mingw )
	EXE=.exe
	;;
	* )
	EXE=""
	;;
	esac
	AC_SUBST([EXE]) # define executable suffix; this is needed for `make clean'

	dnl Checks for supported compiler flags.
	supported_cflags=""
	if test "$EMPTY_CFLAGS" = "no"; then
	supported_cflags="$CFLAGS"
	fi

	dnl For accurate detection, we need warnings as errors.
	dnl I.e. Clang will issue a warning about unsupported flags.
	dnl For the compilation to fail, those warnings needs to be upgraded to errors.
	dnl This will be removed again once the tests are complete (see below).
	WERROR=""
	for w in -Werror -errwarn; do
	if test "x$WERROR" = "x"; then
	AC_MSG_CHECKING([whether the compiler supports $w])
	save_cflags="$CFLAGS"
	AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$w"], [CFLAGS="$CFLAGS $w"])
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
	[WERROR="$w"
	AC_MSG_RESULT([yes])],
	[CFLAGS="$save_cflags"
	AC_MSG_RESULT([no])])
	fi
	done

	dnl Note that -fPIC is also added to LDFLAGS.
	AC_MSG_CHECKING([whether the compiler supports -fPIC])
	save_cflags="$CFLAGS"
	AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="-fPIC"], [CFLAGS="$CFLAGS -fPIC"])
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
	[AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="-fPIC"], [supported_cflags="$supported_cflags -fPIC"])
	AS_IF([test "x$LDFLAGS" = "x"], [LDFLAGS="-fPIC"], [LDFLAGS="$LDFLAGS -fPIC"])
	AC_MSG_RESULT([yes])],
	[CFLAGS="$save_cflags"
	AC_MSG_RESULT([no])])

	if test "$EMPTY_CFLAGS" = "yes"; then
	for f in -Wall -pedantic; do
	AC_MSG_CHECKING([whether the compiler supports $f])
	save_cflags="$CFLAGS"
	AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$f"], [CFLAGS="$CFLAGS $f"])
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
	[AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="$f"], [supported_cflags="$supported_cflags $f"])
	AC_MSG_RESULT([yes])],
	[CFLAGS="$save_cflags"
	AC_MSG_RESULT([no])])
	done

	OOPT=""
	for f in -O4 -O3; do
	if test "x$OOPT" = "x"; then
	AC_MSG_CHECKING([whether the compiler supports $f])
	save_cflags="$CFLAGS"
	AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$f"], [CFLAGS="$CFLAGS $f"])
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
	[AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="$f"], [supported_cflags="$supported_cflags $f"])
	OOPT="$f"
	AC_MSG_RESULT([yes])],
	[CFLAGS="$save_cflags"
	AC_MSG_RESULT([no])])
	fi
	done

	for f in -fexpensive-optimizations -funroll-loops; do
	AC_MSG_CHECKING([whether the compiler supports $f])
	save_cflags="$CFLAGS"
	AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$f"], [CFLAGS="$CFLAGS $f"])
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
	[AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="$f"], [supported_cflags="$supported_cflags $f"])
	AC_MSG_RESULT([yes])],
	[CFLAGS="$save_cflags"
	AC_MSG_RESULT([no])])
	done
	fi

	dnl When turning off warnigns, we're expecting unrecognized command line option errors if they're not
	dnl supported. However, the -Wno-<warning> form isn't consulted unless a warning is triggered.
	dnl At least that's the case for GCC. So to check which warnings we can turn off, we dnl need to check
	dnl if they can be turned on, thereby forcing GCC to take the argument into account right away.
	for f in -Wno-language-extension-token; do
	AC_MSG_CHECKING([whether the compiler supports $f])
	save_cflags="$CFLAGS"
	testf=$(echo "$f" \| $SED 's\|-Wno-\(.*\)\|-W\1\|g')
	AS_IF([test "x$CFLAGS" = "x"], [CFLAGS="$testf"], [CFLAGS="$CFLAGS $testf"])
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
	[AS_IF([test "x$supported_cflags" = "x"], [supported_cflags="$f"], [supported_cflags="$supported_cflags $f"])
	AC_MSG_RESULT([yes])],
	[CFLAGS="$save_cflags"
	AC_MSG_RESULT([no])])
	done

	dnl Remowing -Werror again
	CFLAGS="$supported_cflags"

	dnl Checks for header files.
	AC_HEADER_STDC
	AC_CHECK_HEADERS(
	[unistd.h byteswap.h stdint.h sys/uio.h inttypes.h sys/types.h machine/types.h sys/int_types.h],
	[], [], [AC_INCLUDES_DEFAULT])

	dnl socket() and friends
	AC_CHECK_HEADERS([sys/socket.h netinet/in.h arpa/inet.h], [], [], [AC_INCLUDES_DEFAULT])
	AC_CHECK_HEADERS(
	[windows.h],
	[AC_CHECK_HEADERS([winsock2.h], [], [], [AC_INCLUDES_DEFAULT])],
	[], [AC_INCLUDES_DEFAULT])

	AC_CHECK_TYPES([int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, uint64_t])
	AC_CHECK_SIZEOF([unsigned long])
	AC_CHECK_SIZEOF([unsigned long long])

	dnl Checks for typedefs, structures, and compiler characteristics.
	AC_C_CONST
	AC_C_INLINE
	AC_TYPE_SIZE_T

	dnl Checks for library functions.
	AC_CHECK_FUNCS([socket inet_aton usleep sigaction])

	dnl Find socket function if not found yet.
	if test "x$ac_cv_func_socket" = "xno"; then
	AC_CHECK_LIB([socket], [socket])
	AC_MSG_CHECKING([for socket in -lwsock32])
	SAVELIBS="$LIBS"
	LIBS="$LIBS -lwsock32"
	AC_LINK_IFELSE([AC_LANG_PROGRAM([[
	#include <winsock2.h>
	]], [[
	socket(0, 0, 0);
	]])],[ac_cv_func_socket=yes
	AC_MSG_RESULT([yes])],[LIBS="$SAVELIBS"
	AC_MSG_RESULT([no])])
	fi

	AC_MSG_CHECKING([whether to enable debug logging in all modules])
	AC_ARG_ENABLE([debug-logging],
	[AS_HELP_STRING([--enable-debug-logging], [Enable debug logging in all modules])],
	[], enable_debug_logging=no)
	if test "$enable_debug_logging" = "yes"; then
	AC_DEFINE([ENABLE_DEBUG_LOGGING], [1], [Define to enabled debug logging for all mudules.])
	fi
	AC_MSG_RESULT([$enable_debug_logging])

	PKG_PROG_PKG_CONFIG
	AS_IF([test "x$PKG_CONFIG" != "x"], [PKG_CONFIG="$PKG_CONFIG --static"])

	AC_MSG_CHECKING([whether to leverage OpenSSL crypto])
	AC_ARG_ENABLE([openssl],
	[AS_HELP_STRING([--enable-openssl], [compile in OpenSSL crypto engine])],
	[], [enable_openssl=no])
	AC_MSG_RESULT([$enable_openssl])
	if test "$enable_openssl" = "yes"; then
	AC_MSG_CHECKING([for user specified OpenSSL directory])
	AC_ARG_WITH([openssl-dir],
	[AS_HELP_STRING([--with-openssl-dir], [Location of OpenSSL installation])],
	[if test "x$PKG_CONFIG" != "x" && test -f $with_openssl_dir/lib/pkgconfig/libcrypto.pc; then
	if test "x$PKG_CONFIG_PATH" = "x"; then
	export PKG_CONFIG_PATH="$with_openssl_dir/lib/pkgconfig"
	else
	export PKG_CONFIG_PATH="$with_openssl_dir/lib/pkgconfig:$PKG_CONFIG_PATH"
	fi
	AC_MSG_RESULT([$with_openssl_dir])
	elif test -d $with_openssl_dir/lib; then
	CFLAGS="$CFLAGS -I$with_openssl_dir/include"
	if test "x$LDFLAGS" = "x"; then
	LDFLAGS="-L$with_openssl_dir/lib"
	else
	LDFLAGS="$LDFLAGS -L$with_openssl_dir/lib"
	fi
	AC_MSG_RESULT([$with_openssl_dir])
	else
	AC_MSG_RESULT([invalid])
	AC_MSG_FAILURE([Invalid OpenSSL location: $with_openssl_dir])
	fi],
	[AC_MSG_RESULT([no])])

	if test "x$PKG_CONFIG" != "x"; then
	PKG_CHECK_MODULES([crypto], [libcrypto >= 1.0.1],
	[CFLAGS="$CFLAGS $crypto_CFLAGS"
	LIBS="$crypto_LIBS $LIBS"])
	else
	AC_CHECK_LIB([dl], [dlopen], [], [AC_MSG_WARN([can't find libdl])])
	AC_CHECK_LIB([z], [inflate], [], [AC_MSG_WARN([can't find libz])])
	fi

	AC_SEARCH_LIBS([EVP_EncryptInit], [crypto],
	[], [AC_MSG_FAILURE([can't find openssl >= 1.0.1 crypto lib])])
	AC_SEARCH_LIBS([EVP_aes_128_ctr], [crypto],
	[], [AC_MSG_FAILURE([can't find openssl >= 1.0.1 crypto lib])])
	AC_SEARCH_LIBS([EVP_aes_128_gcm], [crypto],
	[], [AC_MSG_FAILURE([can't find openssl >= 1.0.1 crypto lib])])

	AC_DEFINE([OPENSSL], [1], [Define this to use OpenSSL crypto.])
	AES_ICM_OBJS="crypto/cipher/aes_icm_ossl.o crypto/cipher/aes_gcm_ossl.o"
	HMAC_OBJS=crypto/hash/hmac_ossl.o
	AC_SUBST([USE_OPENSSL], [1])

	AC_MSG_CHECKING([whether to leverage OpenSSL KDF algorithm])
	AC_ARG_ENABLE([openssl-kdf],
	[AS_HELP_STRING([--enable-openssl-kdf], [Use OpenSSL KDF algorithm])],
	[], [enable_openssl_kdf=no])
	AC_MSG_RESULT([$enable_openssl_kdf])
	if test "$enable_openssl_kdf" = "yes"; then
	AC_SEARCH_LIBS([kdf_srtp], [crypto],
	[], [AC_MSG_FAILURE([can't find openssl KDF lib])])
	AC_DEFINE([OPENSSL_KDF], [1], [Define this to use OpenSSL KDF for SRTP.])
	fi
	else
	AES_ICM_OBJS="crypto/cipher/aes_icm.o crypto/cipher/aes.o"
	HMAC_OBJS="crypto/hash/hmac.o crypto/hash/sha1.o"
	fi
	AC_SUBST([AES_ICM_OBJS])
	AC_SUBST([HMAC_OBJS])

	dnl Checking for PCAP
	AC_CHECK_LIB([pcap], [pcap_create],
	[LIBS="-lpcap $LIBS"
	AC_DEFINE([HAVE_PCAP], [1], [Define to 1 if you have the `pcap' library (-lpcap)])
	AC_SUBST([HAVE_PCAP], [1])])

	AC_MSG_CHECKING([whether to redirect logging to stdout])
	AC_ARG_ENABLE([log-stdout],
	[AS_HELP_STRING([--enable-log-stdout], [redirecting logging to stdout])],
	[], [enable_log_stdout=no])
	if test "$enable_log_stdout" = "yes"; then
	AC_DEFINE([ERR_REPORTING_STDOUT], [1], [Define to redirect logging to stdout.])
	fi
	AC_MSG_RESULT([$enable_log_stdout])

	AC_MSG_CHECKING([wheather to use a file for logging])
	AC_ARG_WITH([log-file],
	[AS_HELP_STRING([--with-log-file], [Use file for logging])],
	[AS_CASE([x$with_log_file],
	[x], [valid_with_log_file="no"],
	[xyes], [valid_with_log_file="no"],
	[valid_with_error_file="yes"])
	AS_IF([test "$valid_with_log_file" = "no"],
	[AC_MSG_RESULT([invalid])
	AC_MSG_FAILURE([Invalid value for --with-log-file: "$with_log_file"])],
	[AC_DEFINE_UNQUOTED([ERR_REPORTING_FILE], ["$with_log_file"], [Logging statments will be writen to this file.])
	AC_MSG_RESULT([using log file: "$with_log_file"])])],
	[AC_MSG_RESULT([no])])

	AS_IF(
	[test "$enable_log_stdout" = "yes" && test "x$with_log_file" != "x"],
	[AC_MSG_FAILURE([Can only use one of --enable-log-stdout and --with-log-file; they are mutually exclusive])])

	AC_CONFIG_HEADER([crypto/include/config.h:config_in.h])

	AC_CONFIG_FILES([Makefile crypto/Makefile doc/Makefile libsrtp2.pc])
	AC_OUTPUT

	# This is needed when building outside the source dir.
	AS_MKDIR_P([crypto/cipher])
	AS_MKDIR_P([crypto/hash])
	AS_MKDIR_P([crypto/kernel])
	AS_MKDIR_P([crypto/math])
	AS_MKDIR_P([crypto/replay])
	AS_MKDIR_P([crypto/test])
	AS_MKDIR_P([doc])
	AS_MKDIR_P([srtp])
	AS_MKDIR_P([test])