Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3615 insertions, 0 deletions

diff --git a/src/c-ares/m4/cares-functions.m4 b/src/c-ares/m4/cares-functions.m4
new file mode 100644
index 000000000..7c7c92b53
--- /dev/null
+++ b/src/c-ares/m4/cares-functions.m4
@@ -0,0 +1,3615 @@
+#***************************************************************************
+#
+# Copyright (C) 2008 - 2012 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 46
+
+
+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,
+    [], [], [$cares_includes_arpa_inet])
+])
+
+
+dnl CARES_INCLUDES_FCNTL
+dnl -------------------------------------------------
+dnl Set up variable with list of headers that must be
+dnl included when fcntl.h is to be included.
+
+AC_DEFUN([CARES_INCLUDES_FCNTL], [
+cares_includes_fcntl="\
+/* includes start */
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+#endif
+#ifdef HAVE_UNISTD_H
+#  include <unistd.h>
+#endif
+#ifdef HAVE_FCNTL_H
+#  include <fcntl.h>
+#endif
+/* includes end */"
+  AC_CHECK_HEADERS(
+    sys/types.h unistd.h fcntl.h,
+    [], [], [$cares_includes_fcntl])
+])
+
+
+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,
+    [], [], [$cares_includes_netdb])
+])
+
+
+dnl CARES_INCLUDES_SOCKET
+dnl -------------------------------------------------
+dnl Set up variable with list of headers that must be
+dnl included when socket.h is to be included.
+
+AC_DEFUN([CARES_INCLUDES_SOCKET], [
+cares_includes_socket="\
+/* includes start */
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+#endif
+#ifdef HAVE_SOCKET_H
+#  include <socket.h>
+#endif
+/* includes end */"
+  AC_CHECK_HEADERS(
+    sys/types.h socket.h,
+    [], [], [$cares_includes_socket])
+])
+
+
+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_STROPTS
+dnl -------------------------------------------------
+dnl Set up variable with list of headers that must be
+dnl included when stropts.h is to be included.
+
+AC_DEFUN([CARES_INCLUDES_STROPTS], [
+cares_includes_stropts="\
+/* includes start */
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+#endif
+#ifdef HAVE_UNISTD_H
+#  include <unistd.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#  include <sys/socket.h>
+#endif
+#ifdef HAVE_SYS_IOCTL_H
+#  include <sys/ioctl.h>
+#endif
+#ifdef HAVE_STROPTS_H
+#  include <stropts.h>
+#endif
+/* includes end */"
+  AC_CHECK_HEADERS(
+    sys/types.h unistd.h sys/socket.h sys/ioctl.h stropts.h,
+    [], [], [$cares_includes_stropts])
+])
+
+
+dnl CARES_INCLUDES_SYS_SOCKET
+dnl -------------------------------------------------
+dnl Set up variable with list of headers that must be
+dnl included when sys/socket.h is to be included.
+
+AC_DEFUN([CARES_INCLUDES_SYS_SOCKET], [
+cares_includes_sys_socket="\
+/* includes start */
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#  include <sys/socket.h>
+#endif
+/* includes end */"
+  AC_CHECK_HEADERS(
+    sys/types.h sys/socket.h,
+    [], [], [$cares_includes_sys_socket])
+])
+
+
+dnl CARES_INCLUDES_SYS_TYPES
+dnl -------------------------------------------------
+dnl Set up variable with list of headers that must be
+dnl included when sys/types.h is to be included.
+
+AC_DEFUN([CARES_INCLUDES_SYS_TYPES], [
+cares_includes_sys_types="\
+/* includes start */
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+#endif
+/* includes end */"
+  AC_CHECK_HEADERS(
+    sys/types.h,
+    [], [], [$cares_includes_sys_types])
+])
+
+
+dnl CARES_INCLUDES_SYS_UIO
+dnl -------------------------------------------------
+dnl Set up variable with list of headers that must be
+dnl included when sys/uio.h is to be included.
+
+AC_DEFUN([CARES_INCLUDES_SYS_UIO], [
+cares_includes_sys_uio="\
+/* includes start */
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_UIO_H
+#  include <sys/uio.h>
+#endif
+/* includes end */"
+  AC_CHECK_HEADERS(
+    sys/types.h sys/uio.h,
+    [], [], [$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_PREPROCESS_CALLCONV
+dnl -------------------------------------------------
+dnl Set up variable with a preprocessor block which
+dnl defines function calling convention.
+
+AC_DEFUN([CARES_PREPROCESS_CALLCONV], [
+cares_preprocess_callconv="\
+/* preprocess start */
+#ifdef HAVE_WINDOWS_H
+#  define FUNCALLCONV __stdcall
+#else
+#  define FUNCALLCONV
+#endif
+/* preprocess end */"
+])
+
+
+dnl CARES_CHECK_FUNC_CLOSESOCKET
+dnl -------------------------------------------------
+dnl Verify if closesocket 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_closesocket, then
+dnl HAVE_CLOSESOCKET will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_CLOSESOCKET], [
+  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
+  AC_REQUIRE([CARES_INCLUDES_SOCKET])dnl
+  #
+  tst_links_closesocket="unknown"
+  tst_proto_closesocket="unknown"
+  tst_compi_closesocket="unknown"
+  tst_allow_closesocket="unknown"
+  #
+  AC_MSG_CHECKING([if closesocket can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_winsock2
+      $cares_includes_socket
+    ]],[[
+      if(0 != closesocket(0))
+        return 1;
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_closesocket="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_closesocket="no"
+  ])
+  #
+  if test "$tst_links_closesocket" = "yes"; then
+    AC_MSG_CHECKING([if closesocket is prototyped])
+    AC_EGREP_CPP([closesocket],[
+      $cares_includes_winsock2
+      $cares_includes_socket
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_closesocket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_closesocket="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_closesocket" = "yes"; then
+    AC_MSG_CHECKING([if closesocket is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+        $cares_includes_socket
+      ]],[[
+        if(0 != closesocket(0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_closesocket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_closesocket="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_closesocket" = "yes"; then
+    AC_MSG_CHECKING([if closesocket usage allowed])
+    if test "x$cares_disallow_closesocket" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_closesocket="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_closesocket="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if closesocket might be used])
+  if test "$tst_links_closesocket" = "yes" &&
+     test "$tst_proto_closesocket" = "yes" &&
+     test "$tst_compi_closesocket" = "yes" &&
+     test "$tst_allow_closesocket" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_CLOSESOCKET, 1,
+      [Define to 1 if you have the closesocket function.])
+    ac_cv_func_closesocket="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_closesocket="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_CLOSESOCKET_CAMEL
+dnl -------------------------------------------------
+dnl Verify if CloseSocket 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_closesocket_camel,
+dnl then HAVE_CLOSESOCKET_CAMEL will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_CLOSESOCKET_CAMEL], [
+  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
+  #
+  tst_links_closesocket_camel="unknown"
+  tst_proto_closesocket_camel="unknown"
+  tst_compi_closesocket_camel="unknown"
+  tst_allow_closesocket_camel="unknown"
+  #
+  AC_MSG_CHECKING([if CloseSocket can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_sys_socket
+    ]],[[
+      if(0 != CloseSocket(0))
+        return 1;
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_closesocket_camel="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_closesocket_camel="no"
+  ])
+  #
+  if test "$tst_links_closesocket_camel" = "yes"; then
+    AC_MSG_CHECKING([if CloseSocket is prototyped])
+    AC_EGREP_CPP([CloseSocket],[
+      $cares_includes_sys_socket
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_closesocket_camel="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_closesocket_camel="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_closesocket_camel" = "yes"; then
+    AC_MSG_CHECKING([if CloseSocket is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_sys_socket
+      ]],[[
+        if(0 != CloseSocket(0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_closesocket_camel="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_closesocket_camel="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_closesocket_camel" = "yes"; then
+    AC_MSG_CHECKING([if CloseSocket usage allowed])
+    if test "x$cares_disallow_closesocket_camel" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_closesocket_camel="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_closesocket_camel="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if CloseSocket might be used])
+  if test "$tst_links_closesocket_camel" = "yes" &&
+     test "$tst_proto_closesocket_camel" = "yes" &&
+     test "$tst_compi_closesocket_camel" = "yes" &&
+     test "$tst_allow_closesocket_camel" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_CLOSESOCKET_CAMEL, 1,
+      [Define to 1 if you have the CloseSocket camel case function.])
+    ac_cv_func_closesocket_camel="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_closesocket_camel="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_CONNECT
+dnl -------------------------------------------------
+dnl Verify if connect 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_connect, then
+dnl HAVE_CONNECT will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_CONNECT], [
+  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
+  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
+  AC_REQUIRE([CARES_INCLUDES_SOCKET])dnl
+  #
+  tst_links_connect="unknown"
+  tst_proto_connect="unknown"
+  tst_compi_connect="unknown"
+  tst_allow_connect="unknown"
+  #
+  AC_MSG_CHECKING([if connect can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_winsock2
+      $cares_includes_sys_socket
+      $cares_includes_socket
+    ]],[[
+      if(0 != connect(0, 0, 0))
+        return 1;
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_connect="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_connect="no"
+  ])
+  #
+  if test "$tst_links_connect" = "yes"; then
+    AC_MSG_CHECKING([if connect is prototyped])
+    AC_EGREP_CPP([connect],[
+      $cares_includes_winsock2
+      $cares_includes_sys_socket
+      $cares_includes_socket
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_connect="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_connect="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_connect" = "yes"; then
+    AC_MSG_CHECKING([if connect is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+        $cares_includes_sys_socket
+        $cares_includes_socket
+      ]],[[
+        if(0 != connect(0, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_connect="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_connect="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_connect" = "yes"; then
+    AC_MSG_CHECKING([if connect usage allowed])
+    if test "x$cares_disallow_connect" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_connect="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_connect="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if connect might be used])
+  if test "$tst_links_connect" = "yes" &&
+     test "$tst_proto_connect" = "yes" &&
+     test "$tst_compi_connect" = "yes" &&
+     test "$tst_allow_connect" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_CONNECT, 1,
+      [Define to 1 if you have the connect function.])
+    ac_cv_func_connect="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_connect="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_FCNTL
+dnl -------------------------------------------------
+dnl Verify if fcntl is available, prototyped, and
+dnl can be compiled. If all of these are true, and
+dnl usage has not been previously disallowed with
+dnl shell variable cares_disallow_fcntl, then
+dnl HAVE_FCNTL will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_FCNTL], [
+  AC_REQUIRE([CARES_INCLUDES_FCNTL])dnl
+  #
+  tst_links_fcntl="unknown"
+  tst_proto_fcntl="unknown"
+  tst_compi_fcntl="unknown"
+  tst_allow_fcntl="unknown"
+  #
+  AC_MSG_CHECKING([if fcntl can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([fcntl])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_fcntl="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_fcntl="no"
+  ])
+  #
+  if test "$tst_links_fcntl" = "yes"; then
+    AC_MSG_CHECKING([if fcntl is prototyped])
+    AC_EGREP_CPP([fcntl],[
+      $cares_includes_fcntl
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_fcntl="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_fcntl="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_fcntl" = "yes"; then
+    AC_MSG_CHECKING([if fcntl is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_fcntl
+      ]],[[
+        if(0 != fcntl(0, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_fcntl="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_fcntl="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_fcntl" = "yes"; then
+    AC_MSG_CHECKING([if fcntl usage allowed])
+    if test "x$cares_disallow_fcntl" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_fcntl="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_fcntl="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if fcntl might be used])
+  if test "$tst_links_fcntl" = "yes" &&
+     test "$tst_proto_fcntl" = "yes" &&
+     test "$tst_compi_fcntl" = "yes" &&
+     test "$tst_allow_fcntl" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_FCNTL, 1,
+      [Define to 1 if you have the fcntl function.])
+    ac_cv_func_fcntl="yes"
+    CARES_CHECK_FUNC_FCNTL_O_NONBLOCK
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_fcntl="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_FCNTL_O_NONBLOCK
+dnl -------------------------------------------------
+dnl Verify if fcntl with status flag O_NONBLOCK is
+dnl available, can be compiled, and seems to work. If
+dnl all of these are true, then HAVE_FCNTL_O_NONBLOCK
+dnl will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_FCNTL_O_NONBLOCK], [
+  #
+  tst_compi_fcntl_o_nonblock="unknown"
+  tst_allow_fcntl_o_nonblock="unknown"
+  #
+  case $host_os in
+    sunos4* | aix3* | beos*)
+      dnl O_NONBLOCK does not work on these platforms
+      cares_disallow_fcntl_o_nonblock="yes"
+      ;;
+  esac
+  #
+  if test "$ac_cv_func_fcntl" = "yes"; then
+    AC_MSG_CHECKING([if fcntl O_NONBLOCK is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_fcntl
+      ]],[[
+        int flags = 0;
+        if(0 != fcntl(0, F_SETFL, flags | O_NONBLOCK))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_fcntl_o_nonblock="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_fcntl_o_nonblock="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_fcntl_o_nonblock" = "yes"; then
+    AC_MSG_CHECKING([if fcntl O_NONBLOCK usage allowed])
+    if test "x$cares_disallow_fcntl_o_nonblock" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_fcntl_o_nonblock="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_fcntl_o_nonblock="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if fcntl O_NONBLOCK might be used])
+  if test "$tst_compi_fcntl_o_nonblock" = "yes" &&
+     test "$tst_allow_fcntl_o_nonblock" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_FCNTL_O_NONBLOCK, 1,
+      [Define to 1 if you have a working fcntl O_NONBLOCK function.])
+    ac_cv_func_fcntl_o_nonblock="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_fcntl_o_nonblock="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_FREEADDRINFO
+dnl -------------------------------------------------
+dnl Verify if freeaddrinfo 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_freeaddrinfo, then
+dnl HAVE_FREEADDRINFO will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_FREEADDRINFO], [
+  AC_REQUIRE([CARES_INCLUDES_WS2TCPIP])dnl
+  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
+  AC_REQUIRE([CARES_INCLUDES_NETDB])dnl
+  #
+  tst_links_freeaddrinfo="unknown"
+  tst_proto_freeaddrinfo="unknown"
+  tst_compi_freeaddrinfo="unknown"
+  tst_allow_freeaddrinfo="unknown"
+  #
+  AC_MSG_CHECKING([if freeaddrinfo can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_ws2tcpip
+      $cares_includes_sys_socket
+      $cares_includes_netdb
+    ]],[[
+      freeaddrinfo(0);
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_freeaddrinfo="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_freeaddrinfo="no"
+  ])
+  #
+  if test "$tst_links_freeaddrinfo" = "yes"; then
+    AC_MSG_CHECKING([if freeaddrinfo is prototyped])
+    AC_EGREP_CPP([freeaddrinfo],[
+      $cares_includes_ws2tcpip
+      $cares_includes_sys_socket
+      $cares_includes_netdb
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_freeaddrinfo="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_freeaddrinfo="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_freeaddrinfo" = "yes"; then
+    AC_MSG_CHECKING([if freeaddrinfo is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_ws2tcpip
+        $cares_includes_sys_socket
+        $cares_includes_netdb
+      ]],[[
+        freeaddrinfo(0);
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_freeaddrinfo="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_freeaddrinfo="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_freeaddrinfo" = "yes"; then
+    AC_MSG_CHECKING([if freeaddrinfo usage allowed])
+    if test "x$cares_disallow_freeaddrinfo" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_freeaddrinfo="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_freeaddrinfo="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if freeaddrinfo might be used])
+  if test "$tst_links_freeaddrinfo" = "yes" &&
+     test "$tst_proto_freeaddrinfo" = "yes" &&
+     test "$tst_compi_freeaddrinfo" = "yes" &&
+     test "$tst_allow_freeaddrinfo" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_FREEADDRINFO, 1,
+      [Define to 1 if you have the freeaddrinfo function.])
+    ac_cv_func_freeaddrinfo="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_freeaddrinfo="no"
+  fi
+])
+
+
+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. Additionally when
+dnl HAVE_GETADDRINFO gets defined this will also attempt
+dnl to find out if getaddrinfo happens to be threadsafe,
+dnl defining HAVE_GETADDRINFO_THREADSAFE when true.
+
+AC_DEFUN([CARES_CHECK_FUNC_GETADDRINFO], [
+  AC_REQUIRE([CARES_INCLUDES_WS2TCPIP])dnl
+  AC_REQUIRE([CARES_INCLUDES_STDLIB])dnl
+  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
+  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
+  AC_REQUIRE([CARES_INCLUDES_NETDB])dnl
+  AC_REQUIRE([CURL_CHECK_NATIVE_WINDOWS])dnl
+  #
+  tst_links_getaddrinfo="unknown"
+  tst_proto_getaddrinfo="unknown"
+  tst_compi_getaddrinfo="unknown"
+  tst_works_getaddrinfo="unknown"
+  tst_allow_getaddrinfo="unknown"
+  tst_tsafe_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_string
+        $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 "$tst_works_getaddrinfo" != "no"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_GETADDRINFO, 1,
+      [Define to 1 if you have a working getaddrinfo function.])
+    ac_cv_func_getaddrinfo="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_getaddrinfo="no"
+    ac_cv_func_getaddrinfo_threadsafe="no"
+  fi
+  #
+  if test "$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" &&
+       test "$ac_cv_native_windows" = "yes"; then
+      tst_tsafe_getaddrinfo="yes"
+    fi
+    if test "$tst_tsafe_getaddrinfo" = "unknown"; then
+      CURL_CHECK_DEF_CC([h_errno], [
+        $cares_includes_sys_socket
+        $cares_includes_netdb
+        ], [silent])
+      if test "$curl_cv_have_def_h_errno" = "yes"; then
+        tst_h_errno_macro="yes"
+      else
+        tst_h_errno_macro="no"
+      fi
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([[
+          $cares_includes_sys_socket
+          $cares_includes_netdb
+        ]],[[
+          h_errno = 2;
+          if(0 != h_errno)
+            return 1;
+        ]])
+      ],[
+        tst_h_errno_modifiable_lvalue="yes"
+      ],[
+        tst_h_errno_modifiable_lvalue="no"
+      ])
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([[
+        ]],[[
+#if defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE >= 200809L)
+          return 0;
+#elif defined(_XOPEN_SOURCE) && (_XOPEN_SOURCE >= 700)
+          return 0;
+#else
+          force compilation error
+#endif
+        ]])
+      ],[
+        tst_h_errno_sbs_issue_7="yes"
+      ],[
+        tst_h_errno_sbs_issue_7="no"
+      ])
+      if test "$tst_h_errno_macro" = "no" &&
+         test "$tst_h_errno_modifiable_lvalue" = "no" &&
+         test "$tst_h_errno_sbs_issue_7" = "no"; then
+        tst_tsafe_getaddrinfo="no"
+      else
+        tst_tsafe_getaddrinfo="yes"
+      fi
+    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_GETENV
+dnl -------------------------------------------------
+dnl Verify if getenv 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_getenv, then
+dnl HAVE_GETENV will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_GETENV], [
+  AC_REQUIRE([CARES_INCLUDES_STDLIB])dnl
+  #
+  tst_links_getenv="unknown"
+  tst_proto_getenv="unknown"
+  tst_compi_getenv="unknown"
+  tst_allow_getenv="unknown"
+  #
+  AC_MSG_CHECKING([if getenv can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([getenv])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_getenv="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_getenv="no"
+  ])
+  #
+  if test "$tst_links_getenv" = "yes"; then
+    AC_MSG_CHECKING([if getenv is prototyped])
+    AC_EGREP_CPP([getenv],[
+      $cares_includes_stdlib
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_getenv="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_getenv="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_getenv" = "yes"; then
+    AC_MSG_CHECKING([if getenv is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_stdlib
+      ]],[[
+        if(0 != getenv(0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_getenv="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_getenv="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_getenv" = "yes"; then
+    AC_MSG_CHECKING([if getenv usage allowed])
+    if test "x$cares_disallow_getenv" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_getenv="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_getenv="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if getenv might be used])
+  if test "$tst_links_getenv" = "yes" &&
+     test "$tst_proto_getenv" = "yes" &&
+     test "$tst_compi_getenv" = "yes" &&
+     test "$tst_allow_getenv" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_GETENV, 1,
+      [Define to 1 if you have the getenv function.])
+    ac_cv_func_getenv="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_getenv="no"
+  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
+  AC_REQUIRE([CARES_PREPROCESS_CALLCONV])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([for gethostname arg 2 data type])
+    tst_gethostname_type_arg2="unknown"
+    for tst_arg1 in 'char *' 'unsigned char *' 'void *'; do
+      for tst_arg2 in 'int' 'unsigned int' 'size_t'; do
+        if test "$tst_gethostname_type_arg2" = "unknown"; then
+          AC_COMPILE_IFELSE([
+            AC_LANG_PROGRAM([[
+              $cares_includes_winsock2
+              $cares_includes_unistd
+              $cares_preprocess_callconv
+              extern int FUNCALLCONV gethostname($tst_arg1, $tst_arg2);
+            ]],[[
+              if(0 != gethostname(0, 0))
+                return 1;
+            ]])
+          ],[
+            tst_gethostname_type_arg2="$tst_arg2"
+          ])
+        fi
+      done
+    done
+    AC_MSG_RESULT([$tst_gethostname_type_arg2])
+    if test "$tst_gethostname_type_arg2" != "unknown"; then
+      AC_DEFINE_UNQUOTED(GETHOSTNAME_TYPE_ARG2, $tst_gethostname_type_arg2,
+        [Define to the type of arg 2 for gethostname.])
+    fi
+  fi
+  #
+  if test "$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_NET_PTON
+dnl -------------------------------------------------
+dnl Verify if inet_net_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_net_pton, then
+dnl HAVE_INET_NET_PTON will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_INET_NET_PTON], [
+  AC_REQUIRE([CARES_INCLUDES_STDLIB])dnl
+  AC_REQUIRE([CARES_INCLUDES_ARPA_INET])dnl
+  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
+  #
+  tst_links_inet_net_pton="unknown"
+  tst_proto_inet_net_pton="unknown"
+  tst_compi_inet_net_pton="unknown"
+  tst_works_inet_net_pton="unknown"
+  tst_allow_inet_net_pton="unknown"
+  #
+  AC_MSG_CHECKING([if inet_net_pton can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([inet_net_pton])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_inet_net_pton="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_inet_net_pton="no"
+  ])
+  #
+  if test "$tst_links_inet_net_pton" = "yes"; then
+    AC_MSG_CHECKING([if inet_net_pton is prototyped])
+    AC_EGREP_CPP([inet_net_pton],[
+      $cares_includes_arpa_inet
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_inet_net_pton="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_inet_net_pton="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_inet_net_pton" = "yes"; then
+    AC_MSG_CHECKING([if inet_net_pton is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_arpa_inet
+      ]],[[
+        if(0 != inet_net_pton(0, 0, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_inet_net_pton="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_inet_net_pton="no"
+    ])
+  fi
+  #
+  dnl only do runtime verification when not cross-compiling
+  if test "x$cross_compiling" != "xyes" &&
+    test "$tst_compi_inet_net_pton" = "yes"; then
+    AC_MSG_CHECKING([if inet_net_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 *ipv6net1 = "fe80::214:4fff:fe0b:76c8";
+        const char *ipv6net2 = "::fffe:7f00:1";
+        const char *ipv6net3 = "7f20:1::/64";
+        const char *ipv6net4 = "7f20:1::/2147483649";
+        const char *ipv4net1 = "192.168.100.1";
+        const char *ipv4net2 = "192.168.100/32";
+        const char *ipv4net3 = "192.168.100.1/2147483649";
+        /* - */
+        memset(ipv4a, 1, sizeof(ipv4a));
+        if(32 != inet_net_pton(AF_INET, ipv4net1, ipv4a, 4))
+          exit(1); /* fail */
+        /* - */
+        if( (ipv4a[0x00] != 0xc0) ||
+            (ipv4a[0x01] != 0xa8) ||
+            (ipv4a[0x02] != 0x64) ||
+            (ipv4a[0x03] != 0x01) ||
+            (ipv4a[0x04] != 0x01) )
+          exit(1); /* fail */
+        /* - */
+        memset(ipv4a, 1, sizeof(ipv4a));
+        if(32 != inet_net_pton(AF_INET, ipv4net2, ipv4a, 4))
+          exit(1); /* fail */
+        /* - */
+        if( (ipv4a[0x00] != 0xc0) ||
+            (ipv4a[0x01] != 0xa8) ||
+            (ipv4a[0x02] != 0x64) ||
+            (ipv4a[0x03] != 0x00) ||
+            (ipv4a[0x04] != 0x01) )
+          exit(1); /* fail */
+        /* - */
+        memset(ipv4a, 1, sizeof(ipv4a));
+        if(-1 != inet_net_pton(AF_INET, ipv4net3, ipv4a, 4))
+          exit(1); /* fail */
+        /* - */
+        memset(ipv6a, 1, sizeof(ipv6a));
+        if(128 != inet_net_pton(AF_INET6, ipv6net1, ipv6a, 16))
+          exit(1); /* fail */
+        /* - */
+        if( (ipv6a[0x00] != 0xfe) ||
+            (ipv6a[0x01] != 0x80) ||
+            (ipv6a[0x08] != 0x02) ||
+            (ipv6a[0x09] != 0x14) ||
+            (ipv6a[0x0a] != 0x4f) ||
+            (ipv6a[0x0b] != 0xff) ||
+            (ipv6a[0x0c] != 0xfe) ||
+            (ipv6a[0x0d] != 0x0b) ||
+            (ipv6a[0x0e] != 0x76) ||
+            (ipv6a[0x0f] != 0xc8) ||
+            (ipv6a[0x10] != 0x01) )
+          exit(1); /* fail */
+        /* - */
+        if( (ipv6a[0x02] != 0x0) ||
+            (ipv6a[0x03] != 0x0) ||
+            (ipv6a[0x04] != 0x0) ||
+            (ipv6a[0x05] != 0x0) ||
+            (ipv6a[0x06] != 0x0) ||
+            (ipv6a[0x07] != 0x0) )
+          exit(1); /* fail */
+        /* - */
+        memset(ipv6a, 0, sizeof(ipv6a));
+        ipv6a[0x10] = 0x01;
+        if(128 != inet_net_pton(AF_INET6, ipv6net2, ipv6a, 16))
+          exit(1); /* fail */
+        /* - */
+        if( (ipv6a[0x0a] != 0xff) ||
+            (ipv6a[0x0b] != 0xfe) ||
+            (ipv6a[0x0c] != 0x7f) ||
+            (ipv6a[0x0f] != 0x01) ||
+            (ipv6a[0x10] != 0x01) )
+          exit(1); /* fail */
+        /* - */
+        if( (ipv6a[0x00] != 0x0) ||
+            (ipv6a[0x01] != 0x0) ||
+            (ipv6a[0x02] != 0x0) ||
+            (ipv6a[0x03] != 0x0) ||
+            (ipv6a[0x04] != 0x0) ||
+            (ipv6a[0x05] != 0x0) ||
+            (ipv6a[0x06] != 0x0) ||
+            (ipv6a[0x07] != 0x0) ||
+            (ipv6a[0x08] != 0x0) ||
+            (ipv6a[0x09] != 0x0) ||
+            (ipv6a[0x0d] != 0x0) ||
+            (ipv6a[0x0e] != 0x0) )
+          exit(1); /* fail */
+        /* - */
+        memset(ipv6a, 1, sizeof(ipv6a));
+        if(64 != inet_net_pton(AF_INET6, ipv6net3, ipv6a, 16))
+          exit(1); /* fail */
+        if( (ipv6a[0x00] != 0x7f) ||
+            (ipv6a[0x01] != 0x20) ||
+            (ipv6a[0x03] != 0x01) ||
+            (ipv6a[0x08] != 0x01) ||
+            (ipv6a[0x09] != 0x01) ||
+            (ipv6a[0x0a] != 0x01) ||
+            (ipv6a[0x0b] != 0x01) ||
+            (ipv6a[0x0c] != 0x01) ||
+            (ipv6a[0x0d] != 0x01) ||
+            (ipv6a[0x0e] != 0x01) ||
+            (ipv6a[0x0f] != 0x01) ||
+            (ipv6a[0x10] != 0x01) )
+          exit(1); /* fail */
+        if( (ipv6a[0x02] != 0x0) ||
+            (ipv6a[0x04] != 0x0) ||
+            (ipv6a[0x05] != 0x0) ||
+            (ipv6a[0x06] != 0x0) ||
+            (ipv6a[0x07] != 0x0) ||
+            (ipv6a[0x07] != 0x0) )
+          exit(1); /* fail */
+        /* - */
+        memset(ipv6a, 1, sizeof(ipv6a));
+        if(-1 != inet_net_pton(AF_INET6, ipv6net4, ipv6a, 16))
+          exit(1); /* fail */
+        /* - */
+        exit(0);
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_works_inet_net_pton="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_works_inet_net_pton="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_inet_net_pton" = "yes" &&
+    test "$tst_works_inet_net_pton" != "no"; then
+    AC_MSG_CHECKING([if inet_net_pton usage allowed])
+    if test "x$cares_disallow_inet_net_pton" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_inet_net_pton="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_inet_net_pton="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if inet_net_pton might be used])
+  if test "$tst_links_inet_net_pton" = "yes" &&
+     test "$tst_proto_inet_net_pton" = "yes" &&
+     test "$tst_compi_inet_net_pton" = "yes" &&
+     test "$tst_allow_inet_net_pton" = "yes" &&
+     test "$tst_works_inet_net_pton" != "no"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_INET_NET_PTON, 1,
+      [Define to 1 if you have a IPv6 capable working inet_net_pton function.])
+    ac_cv_func_inet_net_pton="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_inet_net_pton="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_INET_NTOP
+dnl -------------------------------------------------
+dnl Verify if inet_ntop is available, prototyped, can
+dnl be compiled and seems to work. If all of these are
+dnl true, and usage has not been previously disallowed
+dnl with shell variable cares_disallow_inet_ntop, then
+dnl HAVE_INET_NTOP will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_INET_NTOP], [
+  AC_REQUIRE([CARES_INCLUDES_STDLIB])dnl
+  AC_REQUIRE([CARES_INCLUDES_ARPA_INET])dnl
+  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
+  #
+  tst_links_inet_ntop="unknown"
+  tst_proto_inet_ntop="unknown"
+  tst_compi_inet_ntop="unknown"
+  tst_works_inet_ntop="unknown"
+  tst_allow_inet_ntop="unknown"
+  #
+  AC_MSG_CHECKING([if inet_ntop can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([inet_ntop])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_inet_ntop="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_inet_ntop="no"
+  ])
+  #
+  if test "$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$cares_disallow_ioctl_siocgifaddr" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_ioctl_siocgifaddr="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_ioctl_siocgifaddr="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if ioctl SIOCGIFADDR might be used])
+  if test "$tst_compi_ioctl_siocgifaddr" = "yes" &&
+     test "$tst_allow_ioctl_siocgifaddr" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_IOCTL_SIOCGIFADDR, 1,
+      [Define to 1 if you have a working ioctl SIOCGIFADDR function.])
+    ac_cv_func_ioctl_siocgifaddr="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_ioctl_siocgifaddr="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_IOCTLSOCKET
+dnl -------------------------------------------------
+dnl Verify if ioctlsocket 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_ioctlsocket, then
+dnl HAVE_IOCTLSOCKET will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_IOCTLSOCKET], [
+  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
+  #
+  tst_links_ioctlsocket="unknown"
+  tst_proto_ioctlsocket="unknown"
+  tst_compi_ioctlsocket="unknown"
+  tst_allow_ioctlsocket="unknown"
+  #
+  AC_MSG_CHECKING([if ioctlsocket can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_winsock2
+    ]],[[
+      if(0 != ioctlsocket(0, 0, 0))
+        return 1;
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_ioctlsocket="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_ioctlsocket="no"
+  ])
+  #
+  if test "$tst_links_ioctlsocket" = "yes"; then
+    AC_MSG_CHECKING([if ioctlsocket is prototyped])
+    AC_EGREP_CPP([ioctlsocket],[
+      $cares_includes_winsock2
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_ioctlsocket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_ioctlsocket="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_ioctlsocket" = "yes"; then
+    AC_MSG_CHECKING([if ioctlsocket is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+      ]],[[
+        if(0 != ioctlsocket(0, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_ioctlsocket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_ioctlsocket="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_ioctlsocket" = "yes"; then
+    AC_MSG_CHECKING([if ioctlsocket usage allowed])
+    if test "x$cares_disallow_ioctlsocket" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_ioctlsocket="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_ioctlsocket="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if ioctlsocket might be used])
+  if test "$tst_links_ioctlsocket" = "yes" &&
+     test "$tst_proto_ioctlsocket" = "yes" &&
+     test "$tst_compi_ioctlsocket" = "yes" &&
+     test "$tst_allow_ioctlsocket" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_IOCTLSOCKET, 1,
+      [Define to 1 if you have the ioctlsocket function.])
+    ac_cv_func_ioctlsocket="yes"
+    CARES_CHECK_FUNC_IOCTLSOCKET_FIONBIO
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_ioctlsocket="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_IOCTLSOCKET_FIONBIO
+dnl -------------------------------------------------
+dnl Verify if ioctlsocket with the FIONBIO command is
+dnl available, can be compiled, and seems to work. If
+dnl all of these are true, then HAVE_IOCTLSOCKET_FIONBIO
+dnl will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_IOCTLSOCKET_FIONBIO], [
+  #
+  tst_compi_ioctlsocket_fionbio="unknown"
+  tst_allow_ioctlsocket_fionbio="unknown"
+  #
+  if test "$ac_cv_func_ioctlsocket" = "yes"; then
+    AC_MSG_CHECKING([if ioctlsocket FIONBIO is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+      ]],[[
+        int flags = 0;
+        if(0 != ioctlsocket(0, FIONBIO, &flags))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_ioctlsocket_fionbio="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_ioctlsocket_fionbio="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_ioctlsocket_fionbio" = "yes"; then
+    AC_MSG_CHECKING([if ioctlsocket FIONBIO usage allowed])
+    if test "x$cares_disallow_ioctlsocket_fionbio" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_ioctlsocket_fionbio="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_ioctlsocket_fionbio="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if ioctlsocket FIONBIO might be used])
+  if test "$tst_compi_ioctlsocket_fionbio" = "yes" &&
+     test "$tst_allow_ioctlsocket_fionbio" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_IOCTLSOCKET_FIONBIO, 1,
+      [Define to 1 if you have a working ioctlsocket FIONBIO function.])
+    ac_cv_func_ioctlsocket_fionbio="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_ioctlsocket_fionbio="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_IOCTLSOCKET_CAMEL
+dnl -------------------------------------------------
+dnl Verify if IoctlSocket is available, prototyped, and
+dnl can be compiled. If all of these are true, and
+dnl usage has not been previously disallowed with
+dnl shell variable cares_disallow_ioctlsocket_camel,
+dnl then HAVE_IOCTLSOCKET_CAMEL will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_IOCTLSOCKET_CAMEL], [
+  AC_REQUIRE([CARES_INCLUDES_STROPTS])dnl
+  #
+  tst_links_ioctlsocket_camel="unknown"
+  tst_proto_ioctlsocket_camel="unknown"
+  tst_compi_ioctlsocket_camel="unknown"
+  tst_allow_ioctlsocket_camel="unknown"
+  #
+  AC_MSG_CHECKING([if IoctlSocket can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([IoctlSocket])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_ioctlsocket_camel="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_ioctlsocket_camel="no"
+  ])
+  #
+  if test "$tst_links_ioctlsocket_camel" = "yes"; then
+    AC_MSG_CHECKING([if IoctlSocket is prototyped])
+    AC_EGREP_CPP([IoctlSocket],[
+      $cares_includes_stropts
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_ioctlsocket_camel="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_ioctlsocket_camel="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_ioctlsocket_camel" = "yes"; then
+    AC_MSG_CHECKING([if IoctlSocket is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_stropts
+      ]],[[
+        if(0 != IoctlSocket(0, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_ioctlsocket_camel="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_ioctlsocket_camel="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_ioctlsocket_camel" = "yes"; then
+    AC_MSG_CHECKING([if IoctlSocket usage allowed])
+    if test "x$cares_disallow_ioctlsocket_camel" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_ioctlsocket_camel="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_ioctlsocket_camel="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if IoctlSocket might be used])
+  if test "$tst_links_ioctlsocket_camel" = "yes" &&
+     test "$tst_proto_ioctlsocket_camel" = "yes" &&
+     test "$tst_compi_ioctlsocket_camel" = "yes" &&
+     test "$tst_allow_ioctlsocket_camel" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_IOCTLSOCKET_CAMEL, 1,
+      [Define to 1 if you have the IoctlSocket camel case function.])
+    ac_cv_func_ioctlsocket_camel="yes"
+    CARES_CHECK_FUNC_IOCTLSOCKET_CAMEL_FIONBIO
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_ioctlsocket_camel="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_IOCTLSOCKET_CAMEL_FIONBIO
+dnl -------------------------------------------------
+dnl Verify if IoctlSocket with FIONBIO command is available,
+dnl can be compiled, and seems to work. If all of these are
+dnl true, then HAVE_IOCTLSOCKET_CAMEL_FIONBIO will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_IOCTLSOCKET_CAMEL_FIONBIO], [
+  #
+  tst_compi_ioctlsocket_camel_fionbio="unknown"
+  tst_allow_ioctlsocket_camel_fionbio="unknown"
+  #
+  if test "$ac_cv_func_ioctlsocket_camel" = "yes"; then
+    AC_MSG_CHECKING([if IoctlSocket FIONBIO is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_stropts
+      ]],[[
+        long flags = 0;
+        if(0 != ioctlsocket(0, FIONBIO, &flags))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_ioctlsocket_camel_fionbio="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_ioctlsocket_camel_fionbio="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_ioctlsocket_camel_fionbio" = "yes"; then
+    AC_MSG_CHECKING([if IoctlSocket FIONBIO usage allowed])
+    if test "x$cares_disallow_ioctlsocket_camel_fionbio" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_ioctlsocket_camel_fionbio="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_ioctlsocket_camel_fionbio="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if IoctlSocket FIONBIO might be used])
+  if test "$tst_compi_ioctlsocket_camel_fionbio" = "yes" &&
+     test "$tst_allow_ioctlsocket_camel_fionbio" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_IOCTLSOCKET_CAMEL_FIONBIO, 1,
+      [Define to 1 if you have a working IoctlSocket camel case FIONBIO function.])
+    ac_cv_func_ioctlsocket_camel_fionbio="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_ioctlsocket_camel_fionbio="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_SETSOCKOPT
+dnl -------------------------------------------------
+dnl Verify if setsockopt 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_setsockopt, then
+dnl HAVE_SETSOCKOPT will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_SETSOCKOPT], [
+  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
+  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
+  #
+  tst_links_setsockopt="unknown"
+  tst_proto_setsockopt="unknown"
+  tst_compi_setsockopt="unknown"
+  tst_allow_setsockopt="unknown"
+  #
+  AC_MSG_CHECKING([if setsockopt can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_winsock2
+      $cares_includes_sys_socket
+    ]],[[
+      if(0 != setsockopt(0, 0, 0, 0, 0))
+        return 1;
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_setsockopt="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_setsockopt="no"
+  ])
+  #
+  if test "$tst_links_setsockopt" = "yes"; then
+    AC_MSG_CHECKING([if setsockopt is prototyped])
+    AC_EGREP_CPP([setsockopt],[
+      $cares_includes_winsock2
+      $cares_includes_sys_socket
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_setsockopt="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_setsockopt="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_setsockopt" = "yes"; then
+    AC_MSG_CHECKING([if setsockopt is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+        $cares_includes_sys_socket
+      ]],[[
+        if(0 != setsockopt(0, 0, 0, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_setsockopt="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_setsockopt="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_setsockopt" = "yes"; then
+    AC_MSG_CHECKING([if setsockopt usage allowed])
+    if test "x$cares_disallow_setsockopt" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_setsockopt="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_setsockopt="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if setsockopt might be used])
+  if test "$tst_links_setsockopt" = "yes" &&
+     test "$tst_proto_setsockopt" = "yes" &&
+     test "$tst_compi_setsockopt" = "yes" &&
+     test "$tst_allow_setsockopt" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_SETSOCKOPT, 1,
+      [Define to 1 if you have the setsockopt function.])
+    ac_cv_func_setsockopt="yes"
+    CARES_CHECK_FUNC_SETSOCKOPT_SO_NONBLOCK
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_setsockopt="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_SETSOCKOPT_SO_NONBLOCK
+dnl -------------------------------------------------
+dnl Verify if setsockopt with the SO_NONBLOCK command is
+dnl available, can be compiled, and seems to work. If
+dnl all of these are true, then HAVE_SETSOCKOPT_SO_NONBLOCK
+dnl will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_SETSOCKOPT_SO_NONBLOCK], [
+  #
+  tst_compi_setsockopt_so_nonblock="unknown"
+  tst_allow_setsockopt_so_nonblock="unknown"
+  #
+  if test "$ac_cv_func_setsockopt" = "yes"; then
+    AC_MSG_CHECKING([if setsockopt SO_NONBLOCK is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+        $cares_includes_sys_socket
+      ]],[[
+        if(0 != setsockopt(0, SOL_SOCKET, SO_NONBLOCK, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_setsockopt_so_nonblock="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_setsockopt_so_nonblock="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_setsockopt_so_nonblock" = "yes"; then
+    AC_MSG_CHECKING([if setsockopt SO_NONBLOCK usage allowed])
+    if test "x$cares_disallow_setsockopt_so_nonblock" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_setsockopt_so_nonblock="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_setsockopt_so_nonblock="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if setsockopt SO_NONBLOCK might be used])
+  if test "$tst_compi_setsockopt_so_nonblock" = "yes" &&
+     test "$tst_allow_setsockopt_so_nonblock" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_SETSOCKOPT_SO_NONBLOCK, 1,
+      [Define to 1 if you have a working setsockopt SO_NONBLOCK function.])
+    ac_cv_func_setsockopt_so_nonblock="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_setsockopt_so_nonblock="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_SOCKET
+dnl -------------------------------------------------
+dnl Verify if socket 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_socket, then
+dnl HAVE_SOCKET will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_SOCKET], [
+  AC_REQUIRE([CARES_INCLUDES_WINSOCK2])dnl
+  AC_REQUIRE([CARES_INCLUDES_SYS_SOCKET])dnl
+  AC_REQUIRE([CARES_INCLUDES_SOCKET])dnl
+  #
+  tst_links_socket="unknown"
+  tst_proto_socket="unknown"
+  tst_compi_socket="unknown"
+  tst_allow_socket="unknown"
+  #
+  AC_MSG_CHECKING([if socket can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      $cares_includes_winsock2
+      $cares_includes_sys_socket
+      $cares_includes_socket
+    ]],[[
+      if(0 != socket(0, 0, 0))
+        return 1;
+    ]])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_socket="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_socket="no"
+  ])
+  #
+  if test "$tst_links_socket" = "yes"; then
+    AC_MSG_CHECKING([if socket is prototyped])
+    AC_EGREP_CPP([socket],[
+      $cares_includes_winsock2
+      $cares_includes_sys_socket
+      $cares_includes_socket
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_socket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_socket="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_socket" = "yes"; then
+    AC_MSG_CHECKING([if socket is compilable])
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM([[
+        $cares_includes_winsock2
+        $cares_includes_sys_socket
+        $cares_includes_socket
+      ]],[[
+        if(0 != socket(0, 0, 0))
+          return 1;
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_compi_socket="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_compi_socket="no"
+    ])
+  fi
+  #
+  if test "$tst_compi_socket" = "yes"; then
+    AC_MSG_CHECKING([if socket usage allowed])
+    if test "x$cares_disallow_socket" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_socket="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_socket="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if socket might be used])
+  if test "$tst_links_socket" = "yes" &&
+     test "$tst_proto_socket" = "yes" &&
+     test "$tst_compi_socket" = "yes" &&
+     test "$tst_allow_socket" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_SOCKET, 1,
+      [Define to 1 if you have the socket function.])
+    ac_cv_func_socket="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_socket="no"
+  fi
+])
+
+
+dnl CARES_CHECK_FUNC_STRCASECMP
+dnl -------------------------------------------------
+dnl Verify if strcasecmp is available, prototyped, and
+dnl can be compiled. If all of these are true, and
+dnl usage has not been previously disallowed with
+dnl shell variable cares_disallow_strcasecmp, then
+dnl HAVE_STRCASECMP will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_STRCASECMP], [
+  AC_REQUIRE([CARES_INCLUDES_STRING])dnl
+  #
+  tst_links_strcasecmp="unknown"
+  tst_proto_strcasecmp="unknown"
+  tst_compi_strcasecmp="unknown"
+  tst_allow_strcasecmp="unknown"
+  #
+  AC_MSG_CHECKING([if strcasecmp can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([strcasecmp])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_strcasecmp="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_strcasecmp="no"
+  ])
+  #
+  if test "$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
+])