flowspec_next_component
l = flowspec_next_component(buf, len, is_v6, &type);
acomplen = flowspec_next_component(a, alen, is_v6, &atype);
bcomplen = flowspec_next_component(b, blen, is_v6, &btype);
complen = flowspec_next_component(flow, flowlen, is_v6, &t);