bird-filter/filter_aspa.conf

function is_aspa_invalid_customer() {
    int prev_asn = MY_ASN;

    for int cur_asn in bgp_path do {
        if prev_asn != cur_asn && is_aspa_invalid_pair(prev_asn, cur_asn) then
            return true;
        prev_asn = cur_asn;
    }

    return false;
}

function is_aspa_invalid_peer(int peer_asn) {
    int prev_asn = peer_asn;

    for int cur_asn in bgp_path do {
        if cur_asn != peer_asn && prev_asn != cur_asn &&
                is_aspa_invalid_pair(prev_asn, cur_asn) then
            return true;
        prev_asn = cur_asn;
    }

    return false;
}

function is_aspa_invalid_upstream() {
    int prev_asn = MY_ASN;
    int max_up_ramp = bgp_path.len;
    int min_down_ramp = 0;
    int i = 0;

    for int cur_asn in bgp_path do {
        if prev_asn != cur_asn then {
            if is_aspa_invalid_pair(cur_asn, cur_asn) && max_up_ramp > i then
                max_up_ramp = i;

            if is_aspa_invalid_pair(prev_asn, cur_asn) && min_down_ramp < i then
                min_down_ramp = i;
        }

        prev_asn = cur_asn;
        i = i + 1;
    }

    return min_down_ramp > max_up_ramp;
}