],,AC_MSG_ERROR([required C header missing!]))
# Optional header files
-AC_CHECK_HEADERS([ \
+AC_CHECK_HEADERS_ONCE([ \
arpa/inet.h inttypes.h malloc.h netinet/ip.h stdbool.h stddef.h \
stdint.h varargs.h \
])
AC_MSG_ERROR([required function missing!]))
# Optional functions
-AC_CHECK_FUNCS([ \
+AC_CHECK_FUNCS_ONCE([ \
gai_strerror getaddrinfo getnameinfo inet_aton sigaction sigprocmask \
snprintf vsnprintf strdup strlcpy strlcat strtok_r waitpid])