+# enable support for IPv6?
+x_ipv6_on=no
+AC_ARG_ENABLE(ipv6,
+ [ --enable-ipv6, enable IPv6 protocol support],
+ if test "$enableval" = "yes"; then x_ipv6_on=yes; fi
+)
+if test "$x_ipv6_on" = "yes"; then
+ AC_CHECK_FUNCS([ \
+ getaddrinfo getnameinfo \
+ ],,AC_MSG_ERROR([required function missing for IPv6 support!]))
+ AC_DEFINE(WANT_IPV6, 1)
+fi
+