#!/bin/bash

ip link set lo up

$NFT -f - <<EOF
table inet filter {
 chain underflow { }

  chain input {
    type filter hook input priority filter; policy accept;
    icmp type echo-reply accept
    ip saddr 127.0.0.1 ip daddr 127.0.0.2 counter accept
    goto underflow
    }
}
EOF
[ $? -ne 0 ] && exit 1

ping -q -c 1 127.0.0.2 >/dev/null || exit 2

# should work, polict is accept.
ping -q -c 1 127.0.0.1 >/dev/null || exit 1

$NFT -f - <<EOF
table inet filter {
  chain input {
    type filter hook input priority filter; policy drop;
  }
}
EOF
[ $? -ne 0 ] && exit 1

$NFT list ruleset

ping -W 1 -q -c 1 127.0.0.2

ping -q -c 1 127.0.0.2 >/dev/null || exit 2

# should fail, policy is set to drop
ping -W 1 -q -c 1 127.0.0.1 >/dev/null 2>&1 && exit 1

exit 0