#!/usr/sbin/nft -f

<% unless @interfaces.empty? -%>
define external-interfaces = { <%= @interfaces.sort.uniq.join(", ") %> }
<% end -%>
# Exclude 169.254.169.0/24 from ip-private-addresses as is widely by cloud providers.
define ip-private-addresses = { 0.0.0.0, 10.0.0.0/8, 127.0.0.0/8, 169.254.0.0-169.254.168.255, 169.254.170.0-169.254.255.255, 172.16.0.0/12, 192.0.2.0/24, 192.168.0.0/16 }
define ip-multicast-addresses = { 224.0.0.0/4 }
define ip6-private-addresses = { 2001:db8::/32, fc00::/7 }
define ip6-multicast-addresses = { ff00::/8 }

table inet chef-filter {
  set ip-osm-addresses {
    type ipv4_addr
<% unless Array(@hosts[:inet]).empty? -%>
    elements = { <%= Array(@hosts[:inet]).sort.join(", ") %> }
<% end -%>
  }

  set ip6-osm-addresses {
    type ipv6_addr
<% unless Array(@hosts[:inet6]).empty? -%>
    elements = { <%= Array(@hosts[:inet6]).sort.join(", ") %> }
<% end -%>
  }

  set ip-blocklist {
    type ipv4_addr
    flags interval
  }

  set ip6-blocklist {
    type ipv6_addr
    flags interval
  }

  set ratelimit-icmp-echo-ip {
    type ipv4_addr
    flags dynamic
    timeout 120s
  }

  set ratelimit-icmp-echo-ip6 {
    type ipv6_addr
    flags dynamic
    timeout 120s
  }

<% node[:networking][:firewall][:sets].each do |set| -%>
  set <%= set[:name] %> {
    type <%= set[:type] %>
<% if set[:flags] -%>
    flags <%= set[:flags].join(", ") %>
<% end -%>
<% if set[:timeout] -%>
    timeout <%= set[:timeout] %>s
<% end -%>
  }

<% end -%>

<% node[:networking][:firewall][:helpers].each do |helper| -%>
  ct helper <%= helper[:name] %> {
    type "<%= helper[:helper] %>" protocol <%= helper[:protocol] %>
  }

<% end -%>
  chain log-and-drop {
    limit rate 1/second log level notice
    drop
  }

  chain log-and-reject {
    limit rate 1/second log level notice
    reject
  }

  chain incoming {
<% if node[:networking][:firewall][:allowlist].empty? -%>
    ip saddr { $ip-private-addresses, $ip-multicast-addresses } jump log-and-drop
<% else -%>
    ip saddr { $ip-private-addresses, $ip-multicast-addresses } ip saddr != { <%= node[:networking][:firewall][:allowlist].sort.join(", ") %> } jump log-and-drop
<% end -%>
    ip6 saddr { $ip6-private-addresses, $ip6-multicast-addresses } jump log-and-drop

    ip saddr @ip-blocklist jump log-and-drop
    ip6 saddr @ip6-blocklist jump log-and-drop

    icmp type { echo-request } update @ratelimit-icmp-echo-ip { ip saddr limit rate 1/second } accept
    icmp type { echo-request } drop

    icmpv6 type { nd-neighbor-solicit, nd-neighbor-advert, nd-router-solicit, nd-router-advert } accept
    icmpv6 type { echo-request } update @ratelimit-icmp-echo-ip6 { ip6 saddr limit rate 1/second } accept
    icmpv6 type { echo-request } drop

    ct state { established, related } accept

    meta l4proto { icmp, icmpv6 } jump log-and-drop

    tcp flags & (fin|syn|rst|psh|ack|urg) == fin|psh|urg jump log-and-drop
    tcp flags & (fin|syn|rst|psh|ack|urg) == 0x0 jump log-and-drop
    tcp flags & (syn|rst) == syn|rst jump log-and-drop
    tcp flags & (fin|rst) == fin|rst jump log-and-drop
    tcp flags & (fin|syn) == fin|syn jump log-and-drop
    tcp flags & (fin|psh|ack) == fin|psh jump log-and-drop
    tcp sport 0 tcp flags & (fin|syn|rst|ack) == syn jump log-and-drop

<% node[:networking][:firewall][:incoming].uniq.each do |rule| -%>
    <%= rule %>
<% end -%>

    jump log-and-drop
  }

  chain outgoing {
<% if node[:networking][:firewall][:allowlist].empty? -%>
    ip daddr { $ip-private-addresses } jump log-and-drop
<% else -%>
    ip daddr { $ip-private-addresses } ip daddr != { <%= node[:networking][:firewall][:allowlist].sort.join(", ") %> } jump log-and-drop
<% end -%>
    ip6 daddr { $ip6-private-addresses } jump log-and-drop

<% node[:networking][:firewall][:outgoing].each do |rule| -%>
    <%= rule %>
<% end -%>

    accept
  }

  chain input {
    type filter hook input priority filter;

<% unless @interfaces.empty? -%>
    iifname { $external-interfaces } jump incoming
<% end -%>

    accept
  }

  chain forward {
    type filter hook forward priority filter;

<% unless @interfaces.empty? -%>
    iifname { $external-interfaces } jump incoming
    oifname { $external-interfaces } jump outgoing
<% end -%>

    accept
  }

  chain output {
    type filter hook output priority filter;

<% unless @interfaces.empty? -%>
    oifname { $external-interfaces } jump outgoing
<% end -%>

    accept
  }
}
<% if node[:roles].include?("gateway") -%>

table ip chef-nat {
  chain postrouting {
    type nat hook postrouting priority srcnat;

<% node.interfaces(:role => :external).each do |external| -%>
<% node.ipaddresses(:role => :internal, :family => :inet).each do |internal| -%>
    oifname { <%= external[:interface] %> } ip saddr { <%= internal.subnet %> } snat <%= external[:inet][:address] %>
<% end -%>
<% end -%>
  }
}
<% end -%>