[Ferm] ferm @if condition

[Kiss Gabor (Bitman)]

> I'd like to get something like the following, where I can use the @if to only
> be used as a conditional on the differences.
> 
> ======== Desired ========
> @if @eq($DOMAIN, ip) {
>   proto icmp @subchain "icmp"
> }
> @if @eq($DOMAIN, ip6) {
>   proto ipv6-icmp @subchain "ipv6-icmp"
> }
> {
>   icmp-type (
>     # Common icmp type names
>     echo-reply
>     echo-request
>     destination-unreachable
>     time-exceeded
> 
>     @if @eq($DOMAIN, ip6) {
>       # IPv6 ICMP specific additions
>       packet-too-big
>       router-advertisement
>     }
>     ) ACCEPT;
>   }
> }
> ======== End Desired ========

This is my best offer:  :-)

@def $ICMP_COMMON = (echo-reply echo-request destination-unreachable time-exceeded);
@def $ICMP_V6 = (packet-too-big router-advertisement);
@def $ICMP_V4 = ();

proto icmp @subchain "icmp" {
    ACCEPT icmp-type $ICMP_COMMON;
    @if @eq($DOMAIN, ip) {
        ACCEPT icmp-type $ICMP_V4;
    }
    @if @eq($DOMAIN, ip6) {
        ACCEPT icmp-type $ICMP_V6;
    }
}

$ICMP_* vars introduced obly for readability.

Regards

Gabor