src: Allow for empty set variable definition

Allow for empty set definition in variables if they are merged to
non-empty set definition:

 define BASE_ALLOWED_INCOMING_TCP_PORTS = {22, 80, 443}
 define EXTRA_ALLOWED_INCOMING_TCP_PORTS = {}

 table inet filter {
    chain input {
        type filter hook input priority 0; policy drop;
        tcp dport {$BASE_ALLOWED_INCOMING_TCP_PORTS, $EXTRA_ALLOWED_INCOMING_TCP_PORTS} ct state new counter accept
    }
 }

However, disallow this:

 define EXTRA_ALLOWED_INCOMING_TCP_PORTS = {}

 table inet filter {
    chain input {
        type filter hook input priority 0; policy drop;
        tcp dport {$EXTRA_ALLOWED_INCOMING_TCP_PORTS} ct state new counter accept
    }
 }

 # nft -f x.nft
 /tmp/x.nft:6:18-52: Error: Set is empty
        tcp dport {$EXTRA_ALLOWED_INCOMING_TCP_PORTS} ct state new counter accept
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

0 files changed, 0 insertions, 0 deletions