cares-functions.m4

    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_GETADDRINFO, 1,
      [Define to 1 if you have a working getaddrinfo function.])
    ac_cv_func_getaddrinfo="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_getaddrinfo="no"
    ac_cv_func_getaddrinfo_threadsafe="no"
  fi
  #
  if test "$ac_cv_func_getaddrinfo" = "yes"; then
    AC_MSG_CHECKING([if getaddrinfo is threadsafe])
    case $host_os in
      aix[[1234]].* | aix5.[[01]].*)
        dnl aix 5.1 and older
        tst_tsafe_getaddrinfo="no"
        ;;
      aix*)
        dnl aix 5.2 and newer
        tst_tsafe_getaddrinfo="yes"
        ;;
      darwin[[12345]].*)
        dnl darwin 5.0 and mac os x 10.1.X and older
        tst_tsafe_getaddrinfo="no"
        ;;
      darwin*)
        dnl darwin 6.0 and mac os x 10.2.X and newer
        tst_tsafe_getaddrinfo="yes"
        ;;
      freebsd[[1234]].* | freebsd5.[[1234]]*)
        dnl freebsd 5.4 and older
        tst_tsafe_getaddrinfo="no"
        ;;
      freebsd*)
        dnl freebsd 5.5 and newer
        tst_tsafe_getaddrinfo="yes"
        ;;
      hpux[[123456789]].* | hpux10.* | hpux11.0* | hpux11.10*)
        dnl hpux 11.10 and older
        tst_tsafe_getaddrinfo="no"
        ;;
      hpux*)
        dnl hpux 11.11 and newer
        tst_tsafe_getaddrinfo="yes"
        ;;
      netbsd[[123]].*)
        dnl netbsd 3.X and older
        tst_tsafe_getaddrinfo="no"
        ;;
      netbsd*)
        dnl netbsd 4.X and newer
        tst_tsafe_getaddrinfo="yes"
        ;;
      *bsd*)
        dnl All other bsd's
        tst_tsafe_getaddrinfo="no"
        ;;
      solaris2*)
        dnl solaris which have it
        tst_tsafe_getaddrinfo="yes"
        ;;
    esac
    if test "$tst_tsafe_getaddrinfo" = "unknown"; then
      CURL_CHECK_DEF_CC([h_errno], [
        $curl_includes_ws2tcpip
        $curl_includes_sys_socket
        $curl_includes_netdb
        ], [silent])
      if test "$curl_cv_have_def_h_errno" = "no"; then
        tst_tsafe_getaddrinfo="no"
      fi
    fi
    if test "$tst_tsafe_getaddrinfo" = "unknown"; then
      tst_tsafe_getaddrinfo="yes"
    fi
    AC_MSG_RESULT([$tst_tsafe_getaddrinfo])
    if test "$tst_tsafe_getaddrinfo" = "yes"; then
      AC_DEFINE_UNQUOTED(HAVE_GETADDRINFO_THREADSAFE, 1,
        [Define to 1 if the getaddrinfo function is threadsafe.])
      ac_cv_func_getaddrinfo_threadsafe="yes"
    else
      ac_cv_func_getaddrinfo_threadsafe="no"
    fi
  fi
])


dnl CARES_CHECK_FUNC_GETHOSTBYADDR
dnl -------------------------------------------------
dnl Verify if gethostbyaddr is available, prototyped,
dnl and can be compiled. If all of these are true,
dnl and usage has not been previously disallowed with
dnl shell variable cares_disallow_gethostbyaddr, then
dnl HAVE_GETHOSTBYADDR will be defined.

AC_DEFUN([CARES_CHECK_FUNC_GETHOSTBYADDR], [
  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
  AC_REQUIRE([CARES_INCLUDES_NETDB])dnl
  #
  tst_links_gethostbyaddr="unknown"
  tst_proto_gethostbyaddr="unknown"
  tst_compi_gethostbyaddr="unknown"
  tst_allow_gethostbyaddr="unknown"
  #
  AC_MSG_CHECKING([if gethostbyaddr can be linked])
  AC_LINK_IFELSE([
    AC_LANG_PROGRAM([[
      $cares_includes_winsock2
      $cares_includes_netdb
    ]],[[
      if(0 != gethostbyaddr(0, 0, 0))
        return 1;
    ]])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_gethostbyaddr="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_gethostbyaddr="no"
  ])
  #
  if test "$tst_links_gethostbyaddr" = "yes"; then
    AC_MSG_CHECKING([if gethostbyaddr is prototyped])
    AC_EGREP_CPP([gethostbyaddr],[
      $cares_includes_winsock2
      $cares_includes_netdb
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_gethostbyaddr="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_gethostbyaddr="no"
    ])
  fi
  #
  if test "$tst_proto_gethostbyaddr" = "yes"; then
    AC_MSG_CHECKING([if gethostbyaddr is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_winsock2
        $cares_includes_netdb
      ]],[[
        if(0 != gethostbyaddr(0, 0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_gethostbyaddr="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_gethostbyaddr="no"
    ])
  fi
  #
  if test "$tst_compi_gethostbyaddr" = "yes"; then
    AC_MSG_CHECKING([if gethostbyaddr usage allowed])
    if test "x$cares_disallow_gethostbyaddr" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_gethostbyaddr="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_gethostbyaddr="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if gethostbyaddr might be used])
  if test "$tst_links_gethostbyaddr" = "yes" &&
     test "$tst_proto_gethostbyaddr" = "yes" &&
     test "$tst_compi_gethostbyaddr" = "yes" &&
     test "$tst_allow_gethostbyaddr" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_GETHOSTBYADDR, 1,
      [Define to 1 if you have the gethostbyaddr function.])
    ac_cv_func_gethostbyaddr="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_gethostbyaddr="no"
  fi
])


dnl CARES_CHECK_FUNC_GETHOSTBYNAME
dnl -------------------------------------------------
dnl Verify if gethostbyname is available, prototyped,
dnl and can be compiled. If all of these are true,
dnl and usage has not been previously disallowed with
dnl shell variable cares_disallow_gethostbyname, then
dnl HAVE_GETHOSTBYNAME will be defined.

AC_DEFUN([CARES_CHECK_FUNC_GETHOSTBYNAME], [
  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
  AC_REQUIRE([CARES_INCLUDES_NETDB])dnl
  #
  tst_links_gethostbyname="unknown"
  tst_proto_gethostbyname="unknown"
  tst_compi_gethostbyname="unknown"
  tst_allow_gethostbyname="unknown"
  #
  AC_MSG_CHECKING([if gethostbyname can be linked])
  AC_LINK_IFELSE([
    AC_LANG_PROGRAM([[
      $cares_includes_winsock2
      $cares_includes_netdb
    ]],[[
      if(0 != gethostbyname(0))
        return 1;
    ]])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_gethostbyname="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_gethostbyname="no"
  ])
  #
  if test "$tst_links_gethostbyname" = "yes"; then
    AC_MSG_CHECKING([if gethostbyname is prototyped])
    AC_EGREP_CPP([gethostbyname],[
      $cares_includes_winsock2
      $cares_includes_netdb
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_gethostbyname="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_gethostbyname="no"
    ])
  fi
  #
  if test "$tst_proto_gethostbyname" = "yes"; then
    AC_MSG_CHECKING([if gethostbyname is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_winsock2
        $cares_includes_netdb
      ]],[[
        if(0 != gethostbyname(0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_gethostbyname="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_gethostbyname="no"
    ])
  fi
  #
  if test "$tst_compi_gethostbyname" = "yes"; then
    AC_MSG_CHECKING([if gethostbyname usage allowed])
    if test "x$cares_disallow_gethostbyname" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_gethostbyname="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_gethostbyname="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if gethostbyname might be used])
  if test "$tst_links_gethostbyname" = "yes" &&
     test "$tst_proto_gethostbyname" = "yes" &&
     test "$tst_compi_gethostbyname" = "yes" &&
     test "$tst_allow_gethostbyname" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_GETHOSTBYNAME, 1,
      [Define to 1 if you have the gethostbyname function.])
    ac_cv_func_gethostbyname="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_gethostbyname="no"
  fi
])


dnl CARES_CHECK_FUNC_GETHOSTNAME
dnl -------------------------------------------------
dnl Verify if gethostname is available, prototyped, and
dnl can be compiled. If all of these are true, and
dnl usage has not been previously disallowed with
dnl shell variable cares_disallow_gethostname, then
dnl HAVE_GETHOSTNAME will be defined.

AC_DEFUN([CARES_CHECK_FUNC_GETHOSTNAME], [
  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
  AC_REQUIRE([CARES_INCLUDES_UNISTD])dnl
  #
  tst_links_gethostname="unknown"
  tst_proto_gethostname="unknown"
  tst_compi_gethostname="unknown"
  tst_allow_gethostname="unknown"
  #
  AC_MSG_CHECKING([if gethostname can be linked])
  AC_LINK_IFELSE([
    AC_LANG_PROGRAM([[
      $cares_includes_winsock2
      $cares_includes_unistd
    ]],[[
      if(0 != gethostname(0, 0))
        return 1;
    ]])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_gethostname="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_gethostname="no"
  ])
  #
  if test "$tst_links_gethostname" = "yes"; then
    AC_MSG_CHECKING([if gethostname is prototyped])
    AC_EGREP_CPP([gethostname],[
      $cares_includes_winsock2
      $cares_includes_unistd
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_gethostname="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_gethostname="no"
    ])
  fi
  #
  if test "$tst_proto_gethostname" = "yes"; then
    AC_MSG_CHECKING([if gethostname is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_winsock2
        $cares_includes_unistd
      ]],[[
        if(0 != gethostname(0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_gethostname="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_gethostname="no"
    ])
  fi
  #
  if test "$tst_compi_gethostname" = "yes"; then
    AC_MSG_CHECKING([if gethostname usage allowed])
    if test "x$cares_disallow_gethostname" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_gethostname="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_gethostname="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if gethostname might be used])
  if test "$tst_links_gethostname" = "yes" &&
     test "$tst_proto_gethostname" = "yes" &&
     test "$tst_compi_gethostname" = "yes" &&
     test "$tst_allow_gethostname" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_GETHOSTNAME, 1,
      [Define to 1 if you have the gethostname function.])
    ac_cv_func_gethostname="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_gethostname="no"
  fi
])


dnl CARES_CHECK_FUNC_GETSERVBYPORT_R
dnl -------------------------------------------------
dnl Verify if getservbyport_r is available, prototyped,
dnl and can be compiled. If all of these are true, and
dnl usage has not been previously disallowed with
dnl shell variable cares_disallow_getservbyport_r, then
dnl HAVE_GETSERVBYPORT_R will be defined.

AC_DEFUN([CARES_CHECK_FUNC_GETSERVBYPORT_R], [
  AC_REQUIRE([CARES_INCLUDES_NETDB])dnl
  #
  tst_links_getservbyport_r="unknown"
  tst_proto_getservbyport_r="unknown"
  tst_compi_getservbyport_r="unknown"
  tst_allow_getservbyport_r="unknown"
  tst_nargs_getservbyport_r="unknown"
  #
  AC_MSG_CHECKING([if getservbyport_r can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([getservbyport_r])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_getservbyport_r="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_getservbyport_r="no"
  ])
  #
  if test "$tst_links_getservbyport_r" = "yes"; then
    AC_MSG_CHECKING([if getservbyport_r is prototyped])
    AC_EGREP_CPP([getservbyport_r],[
      $cares_includes_netdb
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_getservbyport_r="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_getservbyport_r="no"
    ])
  fi
  #
  if test "$tst_proto_getservbyport_r" = "yes"; then
    if test "$tst_nargs_getservbyport_r" = "unknown"; then
      AC_MSG_CHECKING([if getservbyport_r takes 4 args.])
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([[
          $cares_includes_netdb
        ]],[[
          if(0 != getservbyport_r(0, 0, 0, 0))
            return 1;
        ]])
      ],[
        AC_MSG_RESULT([yes])
        tst_compi_getservbyport_r="yes"
        tst_nargs_getservbyport_r="4"
      ],[
        AC_MSG_RESULT([no])
        tst_compi_getservbyport_r="no"
      ])
    fi
    if test "$tst_nargs_getservbyport_r" = "unknown"; then
      AC_MSG_CHECKING([if getservbyport_r takes 5 args.])
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([[
          $cares_includes_netdb
        ]],[[
          if(0 != getservbyport_r(0, 0, 0, 0, 0))
            return 1;
        ]])
      ],[
        AC_MSG_RESULT([yes])
        tst_compi_getservbyport_r="yes"
        tst_nargs_getservbyport_r="5"
      ],[
        AC_MSG_RESULT([no])
        tst_compi_getservbyport_r="no"
      ])
    fi
    if test "$tst_nargs_getservbyport_r" = "unknown"; then
      AC_MSG_CHECKING([if getservbyport_r takes 6 args.])
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([[
          $cares_includes_netdb
        ]],[[
          if(0 != getservbyport_r(0, 0, 0, 0, 0, 0))
            return 1;
        ]])
      ],[
        AC_MSG_RESULT([yes])
        tst_compi_getservbyport_r="yes"
        tst_nargs_getservbyport_r="6"
      ],[
        AC_MSG_RESULT([no])
        tst_compi_getservbyport_r="no"
      ])
    fi
    AC_MSG_CHECKING([if getservbyport_r is compilable])
    if test "$tst_compi_getservbyport_r" = "yes"; then
      AC_MSG_RESULT([yes])
    else
      AC_MSG_RESULT([no])
    fi
  fi
  #
  if test "$tst_compi_getservbyport_r" = "yes"; then
    AC_MSG_CHECKING([if getservbyport_r usage allowed])
    if test "x$cares_disallow_getservbyport_r" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_getservbyport_r="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_getservbyport_r="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if getservbyport_r might be used])
  if test "$tst_links_getservbyport_r" = "yes" &&
     test "$tst_proto_getservbyport_r" = "yes" &&
     test "$tst_compi_getservbyport_r" = "yes" &&
     test "$tst_allow_getservbyport_r" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_GETSERVBYPORT_R, 1,
      [Define to 1 if you have the getservbyport_r function.])
    AC_DEFINE_UNQUOTED(GETSERVBYPORT_R_ARGS, $tst_nargs_getservbyport_r,
      [Specifies the number of arguments to getservbyport_r])
    if test "$tst_nargs_getservbyport_r" -eq "4"; then
      AC_DEFINE(GETSERVBYPORT_R_BUFSIZE, sizeof(struct servent_data),
        [Specifies the size of the buffer to pass to getservbyport_r])
    else
      AC_DEFINE(GETSERVBYPORT_R_BUFSIZE, 4096,
        [Specifies the size of the buffer to pass to getservbyport_r])
    fi
    ac_cv_func_getservbyport_r="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_getservbyport_r="no"
  fi
])


dnl CARES_CHECK_FUNC_INET_NTOP
dnl -------------------------------------------------
dnl Verify if inet_ntop is available, prototyped, can
dnl be compiled and seems to work. If all of these are
dnl true, and usage has not been previously disallowed
dnl with shell variable cares_disallow_inet_ntop, then
dnl HAVE_INET_NTOP will be defined.

AC_DEFUN([CARES_CHECK_FUNC_INET_NTOP], [
  AC_REQUIRE([CARES_INCLUDES_STDLIB])dnl
  AC_REQUIRE([CARES_INCLUDES_ARPA_INET])dnl
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_inet_ntop="unknown"
  tst_proto_inet_ntop="unknown"
  tst_compi_inet_ntop="unknown"
  tst_works_inet_ntop="unknown"
  tst_allow_inet_ntop="unknown"
  #
  AC_MSG_CHECKING([if inet_ntop can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([inet_ntop])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_inet_ntop="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_inet_ntop="no"
  ])
  #
  if test "$tst_links_inet_ntop" = "yes"; then
    AC_MSG_CHECKING([if inet_ntop is prototyped])
    AC_EGREP_CPP([inet_ntop],[
      $cares_includes_arpa_inet
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_inet_ntop="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_inet_ntop="no"
    ])
  fi
  #
  if test "$tst_proto_inet_ntop" = "yes"; then
    AC_MSG_CHECKING([if inet_ntop is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_arpa_inet
      ]],[[
        if(0 != inet_ntop(0, 0, 0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_inet_ntop="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_inet_ntop="no"
    ])
  fi
  #
  dnl only do runtime verification when not cross-compiling
  if test "x$cross_compiling" != "xyes" &&
    test "$tst_compi_inet_ntop" = "yes"; then
    AC_MSG_CHECKING([if inet_ntop seems to work])
    AC_RUN_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_stdlib
        $cares_includes_arpa_inet
        $cares_includes_string
      ]],[[
        char ipv6res[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
        char ipv4res[sizeof "255.255.255.255"];
        unsigned char ipv6a[26];
        unsigned char ipv4a[5];
        char *ipv6ptr = 0;
        char *ipv4ptr = 0;
        /* - */
        ipv4res[0] = '\0';
        ipv4a[0] = 0xc0;
        ipv4a[1] = 0xa8;
        ipv4a[2] = 0x64;
        ipv4a[3] = 0x01;
        ipv4a[4] = 0x01;
        /* - */
        ipv4ptr = inet_ntop(AF_INET, ipv4a, ipv4res, sizeof(ipv4res));
        if(!ipv4ptr)
          exit(1); /* fail */
        if(ipv4ptr != ipv4res)
          exit(1); /* fail */
        if(!ipv4ptr[0])
          exit(1); /* fail */
        if(memcmp(ipv4res, "192.168.100.1", 13) != 0)
          exit(1); /* fail */
        /* - */
        ipv6res[0] = '\0';
        memset(ipv6a, 0, sizeof(ipv6a));
        ipv6a[0] = 0xfe;
        ipv6a[1] = 0x80;
        ipv6a[8] = 0x02;
        ipv6a[9] = 0x14;
        ipv6a[10] = 0x4f;
        ipv6a[11] = 0xff;
        ipv6a[12] = 0xfe;
        ipv6a[13] = 0x0b;
        ipv6a[14] = 0x76;
        ipv6a[15] = 0xc8;
        ipv6a[25] = 0x01;
        /* - */
        ipv6ptr = inet_ntop(AF_INET6, ipv6a, ipv6res, sizeof(ipv6res));
        if(!ipv6ptr)
          exit(1); /* fail */
        if(ipv6ptr != ipv6res)
          exit(1); /* fail */
        if(!ipv6ptr[0])
          exit(1); /* fail */
        if(memcmp(ipv6res, "fe80::214:4fff:fe0b:76c8", 24) != 0)
          exit(1); /* fail */
        /* - */
        exit(0);
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_works_inet_ntop="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_works_inet_ntop="no"
    ])
  fi
  #
  if test "$tst_compi_inet_ntop" = "yes" &&
    test "$tst_works_inet_ntop" != "no"; then
    AC_MSG_CHECKING([if inet_ntop usage allowed])
    if test "x$cares_disallow_inet_ntop" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_inet_ntop="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_inet_ntop="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if inet_ntop might be used])
  if test "$tst_links_inet_ntop" = "yes" &&
     test "$tst_proto_inet_ntop" = "yes" &&
     test "$tst_compi_inet_ntop" = "yes" &&
     test "$tst_allow_inet_ntop" = "yes" &&
     test "$tst_works_inet_ntop" != "no"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_INET_NTOP, 1,
      [Define to 1 if you have a IPv6 capable working inet_ntop function.])
    ac_cv_func_inet_ntop="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_inet_ntop="no"
  fi
])


dnl CARES_CHECK_FUNC_INET_PTON
dnl -------------------------------------------------
dnl Verify if inet_pton is available, prototyped, can
dnl be compiled and seems to work. If all of these are
dnl true, and usage has not been previously disallowed
dnl with shell variable cares_disallow_inet_pton, then
dnl HAVE_INET_PTON will be defined.

AC_DEFUN([CARES_CHECK_FUNC_INET_PTON], [
  AC_REQUIRE([CARES_INCLUDES_STDLIB])dnl
  AC_REQUIRE([CARES_INCLUDES_ARPA_INET])dnl
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_inet_pton="unknown"
  tst_proto_inet_pton="unknown"
  tst_compi_inet_pton="unknown"
  tst_works_inet_pton="unknown"
  tst_allow_inet_pton="unknown"
  #
  AC_MSG_CHECKING([if inet_pton can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([inet_pton])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_inet_pton="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_inet_pton="no"
  ])
  #
  if test "$tst_links_inet_pton" = "yes"; then
    AC_MSG_CHECKING([if inet_pton is prototyped])
    AC_EGREP_CPP([inet_pton],[
      $cares_includes_arpa_inet
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_inet_pton="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_inet_pton="no"
    ])
  fi
  #
  if test "$tst_proto_inet_pton" = "yes"; then
    AC_MSG_CHECKING([if inet_pton is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_arpa_inet
      ]],[[
        if(0 != inet_pton(0, 0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_inet_pton="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_inet_pton="no"
    ])
  fi
  #
  dnl only do runtime verification when not cross-compiling
  if test "x$cross_compiling" != "xyes" &&
    test "$tst_compi_inet_pton" = "yes"; then
    AC_MSG_CHECKING([if inet_pton seems to work])
    AC_RUN_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_stdlib
        $cares_includes_arpa_inet
        $cares_includes_string
      ]],[[
        unsigned char ipv6a[16+1];
        unsigned char ipv4a[4+1];
        const char *ipv6src = "fe80::214:4fff:fe0b:76c8";
        const char *ipv4src = "192.168.100.1";
        /* - */
        memset(ipv4a, 1, sizeof(ipv4a));
        if(1 != inet_pton(AF_INET, ipv4src, ipv4a))
          exit(1); /* fail */
        /* - */
        if( (ipv4a[0] != 0xc0) ||
            (ipv4a[1] != 0xa8) ||
            (ipv4a[2] != 0x64) ||
            (ipv4a[3] != 0x01) ||
            (ipv4a[4] != 0x01) )
          exit(1); /* fail */
        /* - */
        memset(ipv6a, 1, sizeof(ipv6a));
        if(1 != inet_pton(AF_INET6, ipv6src, ipv6a))
          exit(1); /* fail */
        /* - */
        if( (ipv6a[0]  != 0xfe) ||
            (ipv6a[1]  != 0x80) ||
            (ipv6a[8]  != 0x02) ||
            (ipv6a[9]  != 0x14) ||
            (ipv6a[10] != 0x4f) ||
            (ipv6a[11] != 0xff) ||
            (ipv6a[12] != 0xfe) ||
            (ipv6a[13] != 0x0b) ||
            (ipv6a[14] != 0x76) ||
            (ipv6a[15] != 0xc8) ||
            (ipv6a[16] != 0x01) )
          exit(1); /* fail */
        /* - */
        if( (ipv6a[2]  != 0x0) ||
            (ipv6a[3]  != 0x0) ||
            (ipv6a[4]  != 0x0) ||
            (ipv6a[5]  != 0x0) ||
            (ipv6a[6]  != 0x0) ||
            (ipv6a[7]  != 0x0) )
          exit(1); /* fail */
        /* - */
        exit(0);
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_works_inet_pton="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_works_inet_pton="no"
    ])
  fi
  #
  if test "$tst_compi_inet_pton" = "yes" &&
    test "$tst_works_inet_pton" != "no"; then
    AC_MSG_CHECKING([if inet_pton usage allowed])
    if test "x$cares_disallow_inet_pton" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_inet_pton="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_inet_pton="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if inet_pton might be used])
  if test "$tst_links_inet_pton" = "yes" &&
     test "$tst_proto_inet_pton" = "yes" &&
     test "$tst_compi_inet_pton" = "yes" &&
     test "$tst_allow_inet_pton" = "yes" &&
     test "$tst_works_inet_pton" != "no"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_INET_PTON, 1,
      [Define to 1 if you have a IPv6 capable working inet_pton function.])
    ac_cv_func_inet_pton="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_inet_pton="no"
  fi
])


dnl CARES_CHECK_FUNC_IOCTL
dnl -------------------------------------------------
dnl Verify if ioctl is available, prototyped, and
dnl can be compiled. If all of these are true, and
dnl usage has not been previously disallowed with
dnl shell variable cares_disallow_ioctl, then
dnl HAVE_IOCTL will be defined.

AC_DEFUN([CARES_CHECK_FUNC_IOCTL], [
  AC_REQUIRE([CARES_INCLUDES_STROPTS])dnl
  #
  tst_links_ioctl="unknown"
  tst_proto_ioctl="unknown"
  tst_compi_ioctl="unknown"
  tst_allow_ioctl="unknown"
  #
  AC_MSG_CHECKING([if ioctl can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([ioctl])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_ioctl="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_ioctl="no"
  ])
  #
  if test "$tst_links_ioctl" = "yes"; then
    AC_MSG_CHECKING([if ioctl is prototyped])
    AC_EGREP_CPP([ioctl],[
      $cares_includes_stropts
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_ioctl="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_ioctl="no"
    ])
  fi
  #
  if test "$tst_proto_ioctl" = "yes"; then
    AC_MSG_CHECKING([if ioctl is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_stropts
      ]],[[
        if(0 != ioctl(0, 0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_ioctl="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_ioctl="no"
    ])
  fi
  #
  if test "$tst_compi_ioctl" = "yes"; then
    AC_MSG_CHECKING([if ioctl usage allowed])
    if test "x$cares_disallow_ioctl" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_ioctl="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_ioctl="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if ioctl might be used])
  if test "$tst_links_ioctl" = "yes" &&
     test "$tst_proto_ioctl" = "yes" &&
     test "$tst_compi_ioctl" = "yes" &&
     test "$tst_allow_ioctl" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_IOCTL, 1,
      [Define to 1 if you have the ioctl function.])
    ac_cv_func_ioctl="yes"
    CARES_CHECK_FUNC_IOCTL_FIONBIO
    CARES_CHECK_FUNC_IOCTL_SIOCGIFADDR
  else
    AC_MSG_RESULT([no])
    ac_cv_func_ioctl="no"
  fi
])


dnl CARES_CHECK_FUNC_IOCTL_FIONBIO
dnl -------------------------------------------------
dnl Verify if ioctl with the FIONBIO command is
dnl available, can be compiled, and seems to work. If
dnl all of these are true, then HAVE_IOCTL_FIONBIO
dnl will be defined.

AC_DEFUN([CARES_CHECK_FUNC_IOCTL_FIONBIO], [
  #
  tst_compi_ioctl_fionbio="unknown"
  tst_allow_ioctl_fionbio="unknown"
  #
  if test "$ac_cv_func_ioctl" = "yes"; then
    AC_MSG_CHECKING([if ioctl FIONBIO is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_stropts
      ]],[[
        int flags = 0;
        if(0 != ioctl(0, FIONBIO, &flags))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_ioctl_fionbio="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_ioctl_fionbio="no"
    ])
  fi
  #
  if test "$tst_compi_ioctl_fionbio" = "yes"; then
    AC_MSG_CHECKING([if ioctl FIONBIO usage allowed])
    if test "x$cares_disallow_ioctl_fionbio" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_ioctl_fionbio="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_ioctl_fionbio="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if ioctl FIONBIO might be used])
  if test "$tst_compi_ioctl_fionbio" = "yes" &&
     test "$tst_allow_ioctl_fionbio" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_IOCTL_FIONBIO, 1,
      [Define to 1 if you have a working ioctl FIONBIO function.])
    ac_cv_func_ioctl_fionbio="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_ioctl_fionbio="no"
  fi
])


dnl CARES_CHECK_FUNC_IOCTL_SIOCGIFADDR
dnl -------------------------------------------------
dnl Verify if ioctl with the SIOCGIFADDR command is available,
dnl struct ifreq is defined, they can be compiled, and seem to
dnl work. If all of these are true, then HAVE_IOCTL_SIOCGIFADDR
dnl will be defined.

AC_DEFUN([CARES_CHECK_FUNC_IOCTL_SIOCGIFADDR], [
  #
  tst_compi_ioctl_siocgifaddr="unknown"
  tst_allow_ioctl_siocgifaddr="unknown"
  #
  if test "$ac_cv_func_ioctl" = "yes"; then
    AC_MSG_CHECKING([if ioctl SIOCGIFADDR is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_stropts
        #include <net/if.h>
      ]],[[
        struct ifreq ifr;
        if(0 != ioctl(0, SIOCGIFADDR, &ifr))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_ioctl_siocgifaddr="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_ioctl_siocgifaddr="no"
    ])
  fi
  #
  if test "$tst_compi_ioctl_siocgifaddr" = "yes"; then
    AC_MSG_CHECKING([if ioctl SIOCGIFADDR usage allowed])
    if test "x$cares_disallow_ioctl_siocgifaddr" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_ioctl_siocgifaddr="yes"