+
+AC_SEARCH_LIBS(connect, socket nsl)
+AC_SEARCH_LIBS(inet_ntoa, socket nsl)
+AC_SEARCH_LIBS(inet_addr, socket nsl)
+AC_SEARCH_LIBS(gethostbyname, socket nsl resolv)
+AC_SEARCH_LIBS(getaddrinfo, socket nsl resolv)
+
+AC_CHECK_FUNCS([ftruncate fdopendir lstat64 stat64 memchr munmap select socket strcasecmp strchr strcspn strerror strrchr strspn strtoul strtoull connect inet_ntoa inet_addr gethostbyname getaddrinfo])
+
+AC_ARG_ENABLE([ipv6],
+ AS_HELP_STRING([--disable-ipv6],
+ [disable IPv6 in the built-in web server]),
+ [ipv6=$enableval],[ipv6=$ac_cv_func_getaddrinfo])
+AC_ARG_ENABLE([ipv4],
+ AS_HELP_STRING([--disable-ipv4],
+ [disable IPv4 in the built-in web server]),
+ [ipv4=$enableval],[ipv4=yes])
+if test "$ipv6" = "no"; then
+ AC_DEFINE([NO_IPV6], [1], [define if IPv6 is disabled at configure time])
+fi
+if test "$ipv4" = "no"; then
+ AC_DEFINE([NO_IPV4], [1], [define if IPv4 is disabled at configure time])
+fi