#!/usr/sbin/nft -f

{% macro nat_rule(rule, config, chain) %}
{%   set comment  = '' %}
{%   set base_log = '' %}
{%   set src_addr  = 'ip saddr ' + config.source.address.replace('!','!= ') if config.source is defined and config.source.address is defined and config.source.address is not none %}
{%   set dst_addr  = 'ip daddr ' + config.destination.address.replace('!','!= ') if config.destination is defined and config.destination.address is defined and config.destination.address is not none %}
{#   negated port groups need special treatment, move != in front of { } group #}
{%   if config.source is defined and config.source.port is defined and config.source.port is not none and config.source.port.startswith('!=') %}
{%     set src_port  = 'sport != { ' + config.source.port.replace('!=','') + ' }' %}
{%   else %}
{%     set src_port  = 'sport { ' + config.source.port + ' }' if config.source is defined and config.source.port is defined and config.source.port is not none %}
{%   endif %}
{#   negated port groups need special treatment, move != in front of { } group #}
{%   if config.destination is defined and config.destination.port is defined and config.destination.port is not none and config.destination.port.startswith('!=') %}
{%     set dst_port  = 'dport != { ' + config.destination.port.replace('!=','') + ' }' %}
{%   else %}
{%     set dst_port  = 'dport { ' + config.destination.port + ' }' if config.destination is defined and config.destination.port is defined and config.destination.port is not none %}
{%   endif %}
{%   if chain == 'PREROUTING' %}
{%     set comment   = 'DST-NAT-' + rule %}
{%     set base_log  = '[NAT-DST-' + rule %}
{%     set interface = ' iifname "' + config.inbound_interface + '"' if config.inbound_interface is defined and config.inbound_interface != 'any' else '' %}
{%     if config.translation is defined and config.translation.address is defined and config.translation.address is not none %}
{#       support 1:1 network translation #}
{%       if config.translation.address | is_ip_network %}
{%         set trns_addr = 'dnat ip prefix to ip daddr map { ' + config.destination.address + ' : ' + config.translation.address + ' }' %}
{#         we can now clear out the dst_addr part as it's already covered in aboves map #}
{%         set dst_addr  = '' %}
{%       else %}
{%         set trns_addr = 'dnat to ' + config.translation.address %}
{%       endif %}
{%     endif %}
{%   elif chain == 'POSTROUTING' %}
{%     set comment   = 'SRC-NAT-' + rule %}
{%     set base_log  = '[NAT-SRC-' + rule %}
{%     set interface = ' oifname "' + config.outbound_interface + '"' if config.outbound_interface is defined and config.outbound_interface != 'any' else '' %}
{%     if config.translation is defined and config.translation.address is defined and config.translation.address is not none %}
{%       if config.translation.address == 'masquerade' %}
{%         set trns_addr = config.translation.address %}
{%         if config.translation.port is defined and config.translation.port is not none %}
{%           set trns_addr = trns_addr + ' to ' %}
{%         endif %}
{#       support 1:1 network translation #}
{%       elif config.translation.address | is_ip_network %}
{%         set trns_addr = 'snat ip prefix to ip saddr map { ' + config.source.address + ' : ' + config.translation.address + ' }' %}
{#         we can now clear out the src_addr part as it's already covered in aboves map #}
{%         set src_addr  = '' %}
{%       else %}
{%         set trns_addr = 'snat to ' + config.translation.address %}
{%       endif %}
{%     endif %}
{%   endif %}
{%   set trns_port = ':' + config.translation.port if config.translation is defined and config.translation.port is defined and config.translation.port is not none %}
{#   protocol has a default value thus it is always present #}
{%   if config.protocol == 'tcp_udp' %}
{%     set protocol  = 'tcp' %}
{%     set comment   = comment + ' tcp_udp' %}
{%   else %}
{%     set protocol  = config.protocol %}
{%   endif %}
{%   if config.log is defined %}
{%     if config.exclude is defined %}
{%       set log = base_log + '-EXCL]' %}
{%     elif config.translation is defined and config.translation.address is defined and config.translation.address == 'masquerade' %}
{%       set log = base_log +'-MASQ]' %}
{%     else %}
{%       set log = base_log + ']' %}
{%     endif %}
{%   endif %}
{%   if config.exclude is defined %}
{#     rule has been marked as 'exclude' thus we simply return here #}
{%     set trns_addr = 'return' %}
{%     set trns_port = '' %}
{%   endif %}
{%   set output = 'add rule ip nat ' + chain + interface %}
{%   if protocol != 'all' %}
{%     set output = output + ' ip protocol ' + protocol %}
{%   endif %}
{%   if src_addr %}
{%     set output = output + ' ' + src_addr %}
{%   endif %}
{%   if src_port %}
{%     set output = output + ' ' + protocol + ' ' + src_port %}
{%   endif %}
{%   if dst_addr %}
{%     set output = output + ' ' + dst_addr %}
{%   endif %}
{%   if dst_port %}
{%     set output = output + ' ' + protocol + ' ' + dst_port %}
{%   endif %}
{#   Count packets #}
{%     set output = output + ' counter' %}
{#   Special handling of log option, we must repeat the entire rule before the #}
{#   NAT translation options are added, this is essential                      #}
{%   if log %}
{%     set log_output = output + ' log prefix "' + log + '" comment "' + comment + '"' %}
{%   endif %}
{%   if trns_addr %}
{%     set output = output + ' ' + trns_addr %}
{%   endif %}
{%   if trns_port %}
{#     Do not add a whitespace here, translation port must be directly added after IP address #}
{#     e.g. 192.0.2.10:3389                                                                   #}
{%     set output = output + trns_port %}
{%   endif %}
{%   if comment %}
{%     set output = output + ' comment "' + comment + '"' %}
{%   endif %}
{{ log_output if log_output }}
{{ output }}
{#   Special handling if protocol is tcp_udp, we must repeat the entire rule with udp as protocol #}
{%   if config.protocol == 'tcp_udp' %}
{#     Beware of trailing whitespace, without it the comment tcp_udp will be changed to udp_udp   #}
{{ log_output | replace('tcp ', 'udp ') if log_output }}
{{ output | replace('tcp ', 'udp ') }}
{%   endif %}
{% endmacro %}

# Start with clean NAT table
flush table ip nat
{% if helper_functions == 'remove' %}
{# NAT if going to be disabled - remove rules and targets from nftables #}
{%   set base_command = 'delete rule ip raw' %}
{{ base_command }} PREROUTING handle {{ pre_ct_ignore }}
{{ base_command }} OUTPUT     handle {{ out_ct_ignore }}
{{ base_command }} PREROUTING handle {{ pre_ct_conntrack }}
{{ base_command }} OUTPUT     handle {{ out_ct_conntrack }}

delete chain ip raw NAT_CONNTRACK

{% elif helper_functions == 'add' %}
{# NAT if enabled - add targets to nftables #}
add chain ip raw NAT_CONNTRACK
add rule ip raw NAT_CONNTRACK counter accept
{%   set base_command = 'add rule ip raw' %}
{{ base_command }} PREROUTING position {{ pre_ct_ignore }}    counter jump VYATTA_CT_HELPER
{{ base_command }} OUTPUT     position {{ out_ct_ignore }}    counter jump VYATTA_CT_HELPER
{{ base_command }} PREROUTING position {{ pre_ct_conntrack }} counter jump NAT_CONNTRACK
{{ base_command }} OUTPUT     position {{ out_ct_conntrack }} counter jump NAT_CONNTRACK
{% endif %}

#
# Destination NAT rules build up here
#
{% if destination is defined and destination.rule is defined and destination.rule is not none %}
{%   for rule, config in destination.rule.items() if config.disable is not defined %}
{{ nat_rule(rule, config, 'PREROUTING') }}
{%   endfor %}
{% endif %}
#
# Source NAT rules build up here
#
{% if source is defined and source.rule is defined and source.rule is not none %}
{%   for rule, config in source.rule.items() if config.disable is not defined %}
{{ nat_rule(rule, config, 'POSTROUTING') }}
{%   endfor %}
{% endif %}