#!/usr/sbin/nft -f

# Start with clean NAT table
flush table 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
#
{% for r in destination if not r.disabled -%}
{%   set chain     = "PREROUTING" %}
{%   set src_addr  = "ip saddr " + r.source_address if r.source_address %}
{%   set src_port  = "sport { " + r.source_port +" }" if r.source_port %}
{%   set dst_addr  = "ip daddr " + r.dest_address if r.dest_address %}
{%   set dst_port  = "dport { " + r.dest_port +" }" if r.dest_port %}
{%   set trns_addr = "dnat to " + r.translation_address %}
{%   set trns_port = ":" + r.translation_port if r.translation_port %}
{%   set interface = " iifname \"" + r.interface_in + "\"" %}
{%   set comment   = "DST-NAT-" + r.number %}

{%   if r.protocol == "tcp_udp" %}
{%     set protocol  = "tcp" %}
{%     set comment   = comment + " tcp_udp" %}
{%   else %}
{%     set protocol  = r.protocol %}
{%   endif %}

{%   if r.log %}
{%     set base_log = "[NAT-DST-" + r.number %}
{%     if r.exclude %}
{%       set log = base_log + "-EXCL]" %}
{%     elif r.translation_address == 'masquerade' %}
{%       set log = base_log + "-MASQ]" %}
{%     else %}
{%       set log = base_log + "]" %}
{%     endif %}
{%   endif %}

{%   if r.exclude %}
{#     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 + " counter" %}
{%   set output = output + " comment \"" + comment + "\"" %}

{%   if src_addr %}
{%     set output = output + " " + src_addr %}
{%   endif %}

{%   if src_port %}
{%     set output = output + " " + src_port %}
{%   endif %}

{%   if dst_addr %}
{%     set output = output + " " + dst_addr %}
{%   endif %}

{%   if dst_port %}
{%     set output = output + " " + protocol + " " + dst_port %}
{%   else %}
{%     set output = output + " ip protocol " + protocol %}
{%   endif %}

{#   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 + "\"" %}
{%   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 %}

{{ log_output if log_output }}
{{ output }}

{#   Special handling if protocol is tcp_udp, we must repeat the entire rule with udp as protocol #}
{%   if r.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 %}
{% endfor %}




#
# Source NAT rules build up here
#
{% for r in source if not r.disabled -%}
{%   set chain     = "POSTROUTING" %}
{%   set src_addr  = "ip saddr " + r.source_address if r.source_address %}
{%   set src_port  = "sport { " + r.source_port +" }" if r.source_port %}
{%   set dst_addr  = "ip daddr " + r.dest_address if r.dest_address %}
{%   set dst_port  = "dport { " + r.dest_port +" }" if r.dest_port %}
{%   set trns_addr = "snat to " + r.translation_address if r.translation_address != "masquerade" else "masquerade" %}
{%   set trns_port = ":" + r.translation_port if r.translation_port %}
{%   set comment   = "SRC-NAT-" + r.number %}
{%   set iface     = r.interface_out %}

{%   if r.log %}
{%     if r.exclude %}
{%       set log = "[" + comment + "-EXCL]" %}
{%     elif r.translation_address == 'masquerade' %}
{%       set log = "[" + comment + "-MASQ]" %}
{%     else %}
{%       set log = "[" + comment + "]" %}
{%     endif %}
{%   endif %}

{%   if r.exclude %}
{#     rule has been marked as "exclude" thus we simply return here #}
{%     set trns_addr = "return" %}
{%     set trns_port = "" %}
{%   endif %}

{%   if r.protocol == 'tcp_udp' %}
{#     Special handling for protocol tcp_udp which is represented as two individual rules #}
{%     set comment = comment + " tcp_udp" %}
{%     if log %}

{%       set tcp_dst_port = "tcp " + dst_port if dst_port else "ip protocol tcp" %}
{%       set udp_dst_port = "udp " + dst_port if dst_port else "ip protocol udp" %}
{%       set tcp_src_port = "tcp " + src_port if src_port %}
{%       set udp_src_port = "udp " + src_port if src_port %}

add rule ip nat {{ chain }} oifname "{{ iface }}" {{ tcp_src_port }} {{ src_port }} {{ tcp_dst_port }} {{ dst_addr }} counter log prefix "{{ log }}" comment "{{ comment }}"
{%     endif %}
add rule ip nat {{ chain }} oifname "{{ iface }}" {{ tcp_src_port }} {{ src_port }} {{ tcp_dst_port }} {{ dst_addr }} counter {{ trns_addr }}{{ trns_port }} comment "{{ comment }}"
{%     if log %}
add rule ip nat {{ chain }} oifname "{{ iface }}" {{ udp_src_port }} {{ src_port }} {{ udp_dst_port }} {{ dst_addr }} counter log prefix "{{ log }}" comment "{{ comment }}"
{%     endif %}
add rule ip nat {{ chain }} oifname "{{ iface }}" {{ udp_src_port }} {{ src_port }} {{ udp_dst_port }} {{ dst_addr }} counter {{ trns_addr }}{{ trns_port }} comment "{{ comment }}"

{%   else %}
{%       set proto_dst_port = dst_port if dst_port else "ip protocol " + r.protocol %}
{%       set proto_dst_port = proto_dst_port if r.protocol != "all" %}
{%       set proto_src_port = r.protocol + " " + src_port if r.protocol != "all" else src_port %}

{%     if log %}
add rule ip nat {{ chain }} oifname "{{ iface }}" {{ src_addr }} {{ proto_src_port }} {{ proto_dst_port }} {{ dst_addr }} counter log prefix "{{ log }}" comment "{{ comment }}"
{%     endif %}
add rule ip nat {{ chain }} oifname "{{ iface }}" {{ src_addr }} {{ proto_src_port }} {{ proto_dst_port }} {{ dst_addr }} counter {{ trns_addr }}{{ trns_port }} comment "{{ comment }}"
{%   endif %}
{% endfor %}