#***************************************************************************
# $Id$
#
# Copyright (C) 2008 by Daniel Stenberg et al
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose and without fee is hereby granted, provided
# that the above copyright notice appear in all copies and that both that
# copyright notice and this permission notice appear in supporting
# documentation, and that the name of M.I.T. not be used in advertising or
# publicity pertaining to distribution of the software without specific,
# written prior permission.  M.I.T. makes no representations about the
# suitability of this software for any purpose.  It is provided "as is"
# without express or implied warranty.
#
#***************************************************************************

# File version for 'aclocal' use. Keep it a single number.
# serial 17


dnl CARES_INCLUDES_ARPA_INET
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when arpa/inet.h is to be included.

AC_DEFUN([CARES_INCLUDES_ARPA_INET], [
cares_includes_arpa_inet="\
/* includes start */
#ifdef HAVE_SYS_TYPES_H
#  include <sys/types.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#  include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#  include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#  include <arpa_inet.h>
#endif
/* includes end */"
  AC_CHECK_HEADERS(
    sys/types.h sys/socket.h netinet/in.h arpa/inet.h,
    [], [], [$cares_includes_arpa_inet])
])


dnl CARES_INCLUDES_NETDB
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when netdb.h is to be included.

AC_DEFUN([CARES_INCLUDES_NETDB], [
cares_includes_netdb="\
/* includes start */
#ifdef HAVE_SYS_TYPES_H
#  include <sys/types.h>
#endif
#ifdef HAVE_NETDB_H
#  include <netdb.h>
#endif
/* includes end */"
  AC_CHECK_HEADERS(
    sys/types.h netdb.h,
    [], [], [$cares_includes_netdb])
])


dnl CARES_INCLUDES_STDLIB
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when stdlib.h is to be included.

AC_DEFUN([CARES_INCLUDES_STDLIB], [
cares_includes_stdlib="\
/* includes start */
#ifdef HAVE_SYS_TYPES_H
#  include <sys/types.h>
#endif
#ifdef HAVE_STDLIB_H
#  include <stdlib.h>
#endif
/* includes end */"
  AC_CHECK_HEADERS(
    sys/types.h stdlib.h,
    [], [], [$cares_includes_stdlib])
])


dnl CARES_INCLUDES_STRING
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when string(s).h is to be included.

AC_DEFUN([CARES_INCLUDES_STRING], [
cares_includes_string="\
/* includes start */
#ifdef HAVE_SYS_TYPES_H
#  include <sys/types.h>
#endif
#ifdef HAVE_STRING_H
#  include <string.h>
#endif
#ifdef HAVE_STRINGS_H
#  include <strings.h>
#endif
/* includes end */"
  AC_CHECK_HEADERS(
    sys/types.h string.h strings.h,
    [], [], [$cares_includes_string])
])


dnl CARES_INCLUDES_SYS_SOCKET
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when sys/socket.h is to be included.

AC_DEFUN([CARES_INCLUDES_SYS_SOCKET], [
cares_includes_sys_socket="\
/* includes start */
#ifdef HAVE_SYS_TYPES_H
#  include <sys/types.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#  include <sys/socket.h>
#endif
/* includes end */"
  AC_CHECK_HEADERS(
    sys/types.h sys/socket.h,
    [], [], [$cares_includes_sys_socket])
])


dnl CARES_INCLUDES_SYS_UIO
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when sys/uio.h is to be included.

AC_DEFUN([CARES_INCLUDES_SYS_UIO], [
cares_includes_sys_uio="\
/* includes start */
#ifdef HAVE_SYS_TYPES_H
#  include <sys/types.h>
#endif
#ifdef HAVE_SYS_UIO_H
#  include <sys/uio.h>
#endif
/* includes end */"
  AC_CHECK_HEADERS(
    sys/types.h sys/uio.h,
    [], [], [$cares_includes_sys_uio])
])


dnl CARES_INCLUDES_UNISTD
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when unistd.h is to be included.

AC_DEFUN([CARES_INCLUDES_UNISTD], [
cares_includes_unistd="\
/* includes start */
#ifdef HAVE_SYS_TYPES_H
#  include <sys/types.h>
#endif
#ifdef HAVE_UNISTD_H
#  include <unistd.h>
#endif
/* includes end */"
  AC_CHECK_HEADERS(
    sys/types.h unistd.h,
    [], [], [$cares_includes_unistd])
])


dnl CARES_INCLUDES_WINSOCK2
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when winsock(2).h is to be included.

AC_DEFUN([CARES_INCLUDES_WINSOCK2], [
cares_includes_winsock2="\
/* includes start */
#ifdef HAVE_WINDOWS_H
#  ifndef WIN32_LEAN_AND_MEAN
#    define WIN32_LEAN_AND_MEAN
#  endif
#  include <windows.h>
#  ifdef HAVE_WINSOCK2_H
#    include <winsock2.h>
#  else
#    ifdef HAVE_WINSOCK_H
#      include <winsock.h>
#    endif
#  endif
#endif
/* includes end */"
  CURL_CHECK_HEADER_WINDOWS
  CURL_CHECK_HEADER_WINSOCK
  CURL_CHECK_HEADER_WINSOCK2
])


dnl CARES_INCLUDES_WS2TCPIP
dnl -------------------------------------------------
dnl Set up variable with list of headers that must be
dnl included when ws2tcpip.h is to be included.

AC_DEFUN([CARES_INCLUDES_WS2TCPIP], [
cares_includes_ws2tcpip="\
/* includes start */
#ifdef HAVE_WINDOWS_H
#  ifndef WIN32_LEAN_AND_MEAN
#    define WIN32_LEAN_AND_MEAN
#  endif
#  include <windows.h>
#  ifdef HAVE_WINSOCK2_H
#    include <winsock2.h>
#    ifdef HAVE_WS2TCPIP_H
#       include <ws2tcpip.h>
#    endif
#  endif
#endif
/* includes end */"
  CURL_CHECK_HEADER_WINDOWS
  CURL_CHECK_HEADER_WINSOCK2
  CURL_CHECK_HEADER_WS2TCPIP
])


dnl CARES_CHECK_FUNC_GETADDRINFO
dnl -------------------------------------------------
dnl Verify if getaddrinfo 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_getaddrinfo, then
dnl HAVE_GETADDRINFO will be defined.

AC_DEFUN([CARES_CHECK_FUNC_GETADDRINFO], [
  AC_REQUIRE([CARES_INCLUDES_WS2TCPIP])dnl
  AC_REQUIRE([CARES_INCLUDES_STDLIB])dnl
  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
  AC_REQUIRE([CARES_INCLUDES_NETDB])dnl
  #
  tst_links_getaddrinfo="unknown"
  tst_proto_getaddrinfo="unknown"
  tst_compi_getaddrinfo="unknown"
  tst_works_getaddrinfo="unknown"
  tst_allow_getaddrinfo="unknown"
  #
  AC_MSG_CHECKING([if getaddrinfo can be linked])
  AC_LINK_IFELSE([
    AC_LANG_PROGRAM([[
      $cares_includes_ws2tcpip
      $cares_includes_sys_socket
      $cares_includes_netdb
    ]],[[
      if(0 != getaddrinfo(0, 0, 0, 0))
        return 1;
    ]])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_getaddrinfo="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_getaddrinfo="no"
  ])
  #
  if test "$tst_links_getaddrinfo" = "yes"; then
    AC_MSG_CHECKING([if getaddrinfo is prototyped])
    AC_EGREP_CPP([getaddrinfo],[
      $cares_includes_ws2tcpip
      $cares_includes_sys_socket
      $cares_includes_netdb
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_getaddrinfo="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_getaddrinfo="no"
    ])
  fi
  #
  if test "$tst_proto_getaddrinfo" = "yes"; then
    AC_MSG_CHECKING([if getaddrinfo is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_ws2tcpip
        $cares_includes_sys_socket
        $cares_includes_netdb
      ]],[[
        if(0 != getaddrinfo(0, 0, 0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_getaddrinfo="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_getaddrinfo="no"
    ])
  fi
  #
  dnl only do runtime verification when not cross-compiling
  if test "x$cross_compiling" != "xyes" &&
    test "$tst_compi_getaddrinfo" = "yes"; then
    AC_MSG_CHECKING([if getaddrinfo seems to work])
    AC_RUN_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_ws2tcpip
        $cares_includes_stdlib
        $cares_includes_sys_socket
        $cares_includes_netdb
      ]],[[
        struct addrinfo hints;
        struct addrinfo *ai = 0;
        int error;

        memset(&hints, 0, sizeof(hints));
        hints.ai_flags = AI_NUMERICHOST;
        hints.ai_family = AF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        error = getaddrinfo("127.0.0.1", 0, &hints, &ai);
        if(error || !ai)
          exit(1); /* fail */
        else
          exit(0);
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_works_getaddrinfo="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_works_getaddrinfo="no"
    ])
  fi
  #
  if test "$tst_compi_getaddrinfo" = "yes" &&
    test "$tst_works_getaddrinfo" != "no"; then
    AC_MSG_CHECKING([if getaddrinfo usage allowed])
    if test "x$cares_disallow_getaddrinfo" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_getaddrinfo="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_getaddrinfo="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if getaddrinfo might be used])
  if test "$tst_links_getaddrinfo" = "yes" &&
     test "$tst_proto_getaddrinfo" = "yes" &&
     test "$tst_compi_getaddrinfo" = "yes" &&
     test "$tst_allow_getaddrinfo" = "yes" &&
     test "$tst_works_getaddrinfo" != "no"; then
    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"
  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
        $cares_includes_string
      ]],[[
        unsigned char ipv6a[26];
        unsigned char ipv4a[5];
        const char *ipv6src = "fe80::214:4fff:fe0b:76c8";
        const char *ipv4src = "192.168.100.1";
        /* - */
        memset(ipv4a, 1, sizeof(ipv4a));
        if(1 != inet_pton(AF_INET, ipv4src, ipv4a))
          exit(1); /* fail */
        /* - */
        if( (ipv4a[0] != 0xc0) ||
            (ipv4a[1] != 0xa8) ||
            (ipv4a[2] != 0x64) ||
            (ipv4a[3] != 0x01) ||
            (ipv4a[4] != 0x01) )
          exit(1); /* fail */
        /* - */
        memset(ipv6a, 1, sizeof(ipv6a));
        if(1 != inet_pton(AF_INET6, ipv6src, ipv6a))
          exit(1); /* fail */
        /* - */
        ipv6res[0] = '\0';
        memset(ipv6a, 0, sizeof(ipv6a));
        if( (ipv6a[0]  != 0xfe) ||
            (ipv6a[1]  != 0x80) ||
            (ipv6a[8]  != 0x02) ||
            (ipv6a[9]  != 0x14) ||
            (ipv6a[10] != 0x4f) ||
            (ipv6a[11] != 0xff) ||
            (ipv6a[12] != 0xfe) ||
            (ipv6a[13] != 0x0b) ||
            (ipv6a[14] != 0x76) ||
            (ipv6a[15] != 0xc8) ||
            (ipv6a[25] != 0x01) )
          exit(1); /* fail */
        /* - */
        if( (ipv6a[2]  != 0x0) ||
            (ipv6a[3]  != 0x0) ||
            (ipv6a[4]  != 0x0) ||
            (ipv6a[5]  != 0x0) ||
            (ipv6a[6]  != 0x0) ||
            (ipv6a[7]  != 0x0) ||
            (ipv6a[16] != 0x0) ||
            (ipv6a[17] != 0x0) ||
            (ipv6a[18] != 0x0) ||
            (ipv6a[19] != 0x0) ||
            (ipv6a[20] != 0x0) ||
            (ipv6a[21] != 0x0) ||
            (ipv6a[22] != 0x0) ||
            (ipv6a[23] != 0x0) ||
            (ipv6a[24] != 0x0) )
          exit(1); /* fail */
        /* - */
        exit(0);
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_works_inet_pton="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_works_inet_pton="no"
    ])
  fi
  #
  if test "$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_STRCASECMP
dnl -------------------------------------------------
dnl Verify if strcasecmp 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_strcasecmp, then
dnl HAVE_STRCASECMP will be defined.

AC_DEFUN([CARES_CHECK_FUNC_STRCASECMP], [
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_strcasecmp="unknown"
  tst_proto_strcasecmp="unknown"
  tst_compi_strcasecmp="unknown"
  tst_allow_strcasecmp="unknown"
  #
  AC_MSG_CHECKING([if strcasecmp can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([strcasecmp])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_strcasecmp="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_strcasecmp="no"
  ])
  #
  if test "$tst_links_strcasecmp" = "yes"; then
    AC_MSG_CHECKING([if strcasecmp is prototyped])
    AC_EGREP_CPP([strcasecmp],[
      $cares_includes_string
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_strcasecmp="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_strcasecmp="no"
    ])
  fi
  #
  if test "$tst_proto_strcasecmp" = "yes"; then
    AC_MSG_CHECKING([if strcasecmp is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_string
      ]],[[
        if(0 != strcasecmp(0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_strcasecmp="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_strcasecmp="no"
    ])
  fi
  #
  if test "$tst_compi_strcasecmp" = "yes"; then
    AC_MSG_CHECKING([if strcasecmp usage allowed])
    if test "x$cares_disallow_strcasecmp" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_strcasecmp="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_strcasecmp="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if strcasecmp might be used])
  if test "$tst_links_strcasecmp" = "yes" &&
     test "$tst_proto_strcasecmp" = "yes" &&
     test "$tst_compi_strcasecmp" = "yes" &&
     test "$tst_allow_strcasecmp" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_STRCASECMP, 1,
      [Define to 1 if you have the strcasecmp function.])
    ac_cv_func_strcasecmp="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_strcasecmp="no"
  fi
])


dnl CARES_CHECK_FUNC_STRCMPI
dnl -------------------------------------------------
dnl Verify if strcmpi 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_strcmpi, then
dnl HAVE_STRCMPI will be defined.

AC_DEFUN([CARES_CHECK_FUNC_STRCMPI], [
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_strcmpi="unknown"
  tst_proto_strcmpi="unknown"
  tst_compi_strcmpi="unknown"
  tst_allow_strcmpi="unknown"
  #
  AC_MSG_CHECKING([if strcmpi can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([strcmpi])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_strcmpi="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_strcmpi="no"
  ])
  #
  if test "$tst_links_strcmpi" = "yes"; then
    AC_MSG_CHECKING([if strcmpi is prototyped])
    AC_EGREP_CPP([strcmpi],[
      $cares_includes_string
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_strcmpi="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_strcmpi="no"
    ])
  fi
  #
  if test "$tst_proto_strcmpi" = "yes"; then
    AC_MSG_CHECKING([if strcmpi is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_string
      ]],[[
        if(0 != strcmpi(0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_strcmpi="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_strcmpi="no"
    ])
  fi
  #
  if test "$tst_compi_strcmpi" = "yes"; then
    AC_MSG_CHECKING([if strcmpi usage allowed])
    if test "x$cares_disallow_strcmpi" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_strcmpi="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_strcmpi="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if strcmpi might be used])
  if test "$tst_links_strcmpi" = "yes" &&
     test "$tst_proto_strcmpi" = "yes" &&
     test "$tst_compi_strcmpi" = "yes" &&
     test "$tst_allow_strcmpi" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_STRCMPI, 1,
      [Define to 1 if you have the strcmpi function.])
    ac_cv_func_strcmpi="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_strcmpi="no"
  fi
])


dnl CARES_CHECK_FUNC_STRDUP
dnl -------------------------------------------------
dnl Verify if strdup 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_strdup, then
dnl HAVE_STRDUP will be defined.

AC_DEFUN([CARES_CHECK_FUNC_STRDUP], [
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_strdup="unknown"
  tst_proto_strdup="unknown"
  tst_compi_strdup="unknown"
  tst_allow_strdup="unknown"
  #
  AC_MSG_CHECKING([if strdup can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([strdup])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_strdup="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_strdup="no"
  ])
  #
  if test "$tst_links_strdup" = "yes"; then
    AC_MSG_CHECKING([if strdup is prototyped])
    AC_EGREP_CPP([strdup],[
      $cares_includes_string
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_strdup="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_strdup="no"
    ])
  fi
  #
  if test "$tst_proto_strdup" = "yes"; then
    AC_MSG_CHECKING([if strdup is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_string
      ]],[[
        if(0 != strdup(0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_strdup="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_strdup="no"
    ])
  fi
  #
  if test "$tst_compi_strdup" = "yes"; then
    AC_MSG_CHECKING([if strdup usage allowed])
    if test "x$cares_disallow_strdup" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_strdup="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_strdup="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if strdup might be used])
  if test "$tst_links_strdup" = "yes" &&
     test "$tst_proto_strdup" = "yes" &&
     test "$tst_compi_strdup" = "yes" &&
     test "$tst_allow_strdup" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_STRDUP, 1,
      [Define to 1 if you have the strdup function.])
    ac_cv_func_strdup="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_strdup="no"
  fi
])


dnl CARES_CHECK_FUNC_STRICMP
dnl -------------------------------------------------
dnl Verify if stricmp 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_stricmp, then
dnl HAVE_STRICMP will be defined.

AC_DEFUN([CARES_CHECK_FUNC_STRICMP], [
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_stricmp="unknown"
  tst_proto_stricmp="unknown"
  tst_compi_stricmp="unknown"
  tst_allow_stricmp="unknown"
  #
  AC_MSG_CHECKING([if stricmp can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([stricmp])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_stricmp="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_stricmp="no"
  ])
  #
  if test "$tst_links_stricmp" = "yes"; then
    AC_MSG_CHECKING([if stricmp is prototyped])
    AC_EGREP_CPP([stricmp],[
      $cares_includes_string
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_stricmp="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_stricmp="no"
    ])
  fi
  #
  if test "$tst_proto_stricmp" = "yes"; then
    AC_MSG_CHECKING([if stricmp is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_string
      ]],[[
        if(0 != stricmp(0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_stricmp="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_stricmp="no"
    ])
  fi
  #
  if test "$tst_compi_stricmp" = "yes"; then
    AC_MSG_CHECKING([if stricmp usage allowed])
    if test "x$cares_disallow_stricmp" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_stricmp="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_stricmp="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if stricmp might be used])
  if test "$tst_links_stricmp" = "yes" &&
     test "$tst_proto_stricmp" = "yes" &&
     test "$tst_compi_stricmp" = "yes" &&
     test "$tst_allow_stricmp" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_STRICMP, 1,
      [Define to 1 if you have the stricmp function.])
    ac_cv_func_stricmp="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_stricmp="no"
  fi
])


dnl CARES_CHECK_FUNC_STRNCASECMP
dnl -------------------------------------------------
dnl Verify if strncasecmp 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_strncasecmp, then
dnl HAVE_STRNCASECMP will be defined.

AC_DEFUN([CARES_CHECK_FUNC_STRNCASECMP], [
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_strncasecmp="unknown"
  tst_proto_strncasecmp="unknown"
  tst_compi_strncasecmp="unknown"
  tst_allow_strncasecmp="unknown"
  #
  AC_MSG_CHECKING([if strncasecmp can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([strncasecmp])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_strncasecmp="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_strncasecmp="no"
  ])
  #
  if test "$tst_links_strncasecmp" = "yes"; then
    AC_MSG_CHECKING([if strncasecmp is prototyped])
    AC_EGREP_CPP([strncasecmp],[
      $cares_includes_string
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_strncasecmp="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_strncasecmp="no"
    ])
  fi
  #
  if test "$tst_proto_strncasecmp" = "yes"; then
    AC_MSG_CHECKING([if strncasecmp is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_string
      ]],[[
        if(0 != strncasecmp(0, 0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_strncasecmp="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_strncasecmp="no"
    ])
  fi
  #
  if test "$tst_compi_strncasecmp" = "yes"; then
    AC_MSG_CHECKING([if strncasecmp usage allowed])
    if test "x$cares_disallow_strncasecmp" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_strncasecmp="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_strncasecmp="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if strncasecmp might be used])
  if test "$tst_links_strncasecmp" = "yes" &&
     test "$tst_proto_strncasecmp" = "yes" &&
     test "$tst_compi_strncasecmp" = "yes" &&
     test "$tst_allow_strncasecmp" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_STRNCASECMP, 1,
      [Define to 1 if you have the strncasecmp function.])
    ac_cv_func_strncasecmp="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_strncasecmp="no"
  fi
])


dnl CARES_CHECK_FUNC_STRNCMPI
dnl -------------------------------------------------
dnl Verify if strncmpi 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_strncmpi, then
dnl HAVE_STRNCMPI will be defined.

AC_DEFUN([CARES_CHECK_FUNC_STRNCMPI], [
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_strncmpi="unknown"
  tst_proto_strncmpi="unknown"
  tst_compi_strncmpi="unknown"
  tst_allow_strncmpi="unknown"
  #
  AC_MSG_CHECKING([if strncmpi can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([strncmpi])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_strncmpi="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_strncmpi="no"
  ])
  #
  if test "$tst_links_strncmpi" = "yes"; then
    AC_MSG_CHECKING([if strncmpi is prototyped])
    AC_EGREP_CPP([strncmpi],[
      $cares_includes_string
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_strncmpi="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_strncmpi="no"
    ])
  fi
  #
  if test "$tst_proto_strncmpi" = "yes"; then
    AC_MSG_CHECKING([if strncmpi is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_string
      ]],[[
        if(0 != strncmpi(0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_strncmpi="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_strncmpi="no"
    ])
  fi
  #
  if test "$tst_compi_strncmpi" = "yes"; then
    AC_MSG_CHECKING([if strncmpi usage allowed])
    if test "x$cares_disallow_strncmpi" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_strncmpi="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_strncmpi="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if strncmpi might be used])
  if test "$tst_links_strncmpi" = "yes" &&
     test "$tst_proto_strncmpi" = "yes" &&
     test "$tst_compi_strncmpi" = "yes" &&
     test "$tst_allow_strncmpi" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_STRNCMPI, 1,
      [Define to 1 if you have the strncmpi function.])
    ac_cv_func_strncmpi="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_strncmpi="no"
  fi
])


dnl CARES_CHECK_FUNC_STRNICMP
dnl -------------------------------------------------
dnl Verify if strnicmp 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_strnicmp, then
dnl HAVE_STRNICMP will be defined.

AC_DEFUN([CARES_CHECK_FUNC_STRNICMP], [
  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
  #
  tst_links_strnicmp="unknown"
  tst_proto_strnicmp="unknown"
  tst_compi_strnicmp="unknown"
  tst_allow_strnicmp="unknown"
  #
  AC_MSG_CHECKING([if strnicmp can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([strnicmp])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_strnicmp="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_strnicmp="no"
  ])
  #
  if test "$tst_links_strnicmp" = "yes"; then
    AC_MSG_CHECKING([if strnicmp is prototyped])
    AC_EGREP_CPP([strnicmp],[
      $cares_includes_string
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_strnicmp="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_strnicmp="no"
    ])
  fi
  #
  if test "$tst_proto_strnicmp" = "yes"; then
    AC_MSG_CHECKING([if strnicmp is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_string
      ]],[[
        if(0 != strnicmp(0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_strnicmp="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_strnicmp="no"
    ])
  fi
  #
  if test "$tst_compi_strnicmp" = "yes"; then
    AC_MSG_CHECKING([if strnicmp usage allowed])
    if test "x$cares_disallow_strnicmp" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_strnicmp="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_strnicmp="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if strnicmp might be used])
  if test "$tst_links_strnicmp" = "yes" &&
     test "$tst_proto_strnicmp" = "yes" &&
     test "$tst_compi_strnicmp" = "yes" &&
     test "$tst_allow_strnicmp" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_STRNICMP, 1,
      [Define to 1 if you have the strnicmp function.])
    ac_cv_func_strnicmp="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_strnicmp="no"
  fi
])


dnl CARES_CHECK_FUNC_WRITEV
dnl -------------------------------------------------
dnl Verify if writev 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_writev, then
dnl HAVE_WRITEV will be defined.

AC_DEFUN([CARES_CHECK_FUNC_WRITEV], [
  AC_REQUIRE([CARES_INCLUDES_SYS_UIO])dnl
  #
  tst_links_writev="unknown"
  tst_proto_writev="unknown"
  tst_compi_writev="unknown"
  tst_allow_writev="unknown"
  #
  AC_MSG_CHECKING([if writev can be linked])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([writev])
  ],[
    AC_MSG_RESULT([yes])
    tst_links_writev="yes"
  ],[
    AC_MSG_RESULT([no])
    tst_links_writev="no"
  ])
  #
  if test "$tst_links_writev" = "yes"; then
    AC_MSG_CHECKING([if writev is prototyped])
    AC_EGREP_CPP([writev],[
      $cares_includes_sys_uio
    ],[
      AC_MSG_RESULT([yes])
      tst_proto_writev="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_proto_writev="no"
    ])
  fi
  #
  if test "$tst_proto_writev" = "yes"; then
    AC_MSG_CHECKING([if writev is compilable])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
        $cares_includes_sys_uio
      ]],[[
        if(0 != writev(0, 0, 0))
          return 1;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tst_compi_writev="yes"
    ],[
      AC_MSG_RESULT([no])
      tst_compi_writev="no"
    ])
  fi
  #
  if test "$tst_compi_writev" = "yes"; then
    AC_MSG_CHECKING([if writev usage allowed])
    if test "x$cares_disallow_writev" != "xyes"; then
      AC_MSG_RESULT([yes])
      tst_allow_writev="yes"
    else
      AC_MSG_RESULT([no])
      tst_allow_writev="no"
    fi
  fi
  #
  AC_MSG_CHECKING([if writev might be used])
  if test "$tst_links_writev" = "yes" &&
     test "$tst_proto_writev" = "yes" &&
     test "$tst_compi_writev" = "yes" &&
     test "$tst_allow_writev" = "yes"; then
    AC_MSG_RESULT([yes])
    AC_DEFINE_UNQUOTED(HAVE_WRITEV, 1,
      [Define to 1 if you have the writev function.])
    ac_cv_func_writev="yes"
  else
    AC_MSG_RESULT([no])
    ac_cv_func_writev="no"
  fi
])