nat: T2198: restructure DNAT template part for less duplicated code

Build up only one output rule string by appending the configuration part by
part.

1 files changed, 72 insertions, 32 deletions

diff --git a/data/templates/firewall/nftables-nat.tmpl b/data/templates/firewall/nftables-nat.tmpl
index 9bab8b363..5ce110d82 100644
--- a/data/templates/firewall/nftables-nat.tmpl
+++ b/data/templates/firewall/nftables-nat.tmpl
@@ -5,10 +5,12 @@ flush table nat
 
 {% if helper_functions == 'remove' %}
 {# NAT if going to be disabled - remove rules and targets from nftables #}
-delete rule ip raw PREROUTING handle {{ pre_ct_ignore }}
-delete rule ip raw PREROUTING handle {{ pre_ct_conntrack }}
-delete rule ip raw OUTPUT handle {{ out_ct_ignore }}
-delete rule ip raw OUTPUT handle {{ out_ct_conntrack }}
+
+{% 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
 
@@ -17,13 +19,17 @@ delete chain ip raw NAT_CONNTRACK
 add chain ip raw NAT_CONNTRACK
 add rule ip raw NAT_CONNTRACK counter accept
 
-add rule ip raw PREROUTING position {{ pre_ct_ignore }} counter jump VYATTA_CT_HELPER
-add rule ip raw PREROUTING position {{ pre_ct_conntrack }} counter jump NAT_CONNTRACK
-add rule ip raw OUTPUT position {{ out_ct_ignore }} counter jump VYATTA_CT_HELPER
-add rule ip raw OUTPUT position {{ out_ct_conntrack }} counter jump NAT_CONNTRACK
-{% endif %}
+{% 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 %}
@@ -32,16 +38,24 @@ add rule ip raw OUTPUT position {{ out_ct_conntrack }} counter jump NAT_CONNTRAC
 {%   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 %}
-{%   set iface     = r.interface_in %}
+
+{%   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 = "[" + comment + "-EXCL]" %}
+{%       set log = base_log + "-EXCL]" %}
 {%     elif r.translation_address == 'masquerade' %}
-{%       set log = "[" + comment + "-MASQ]" %}
+{%       set log = base_log + "-MASQ]" %}
 {%     else %}
-{%       set log = "[" + comment + "]" %}
+{%       set log = base_log + "]" %}
 {%     endif %}
 {%   endif %}
 
@@ -51,34 +65,60 @@ add rule ip raw OUTPUT position {{ out_ct_conntrack }} counter jump NAT_CONNTRAC
 {%     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 output = "add rule ip nat " + chain + interface + " counter" %}
+{%   set output = output + " comment \"" + comment + "\"" %}
 
-{%       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" %}
+{%   if src_addr %}
+{%     set output = output + " " + src_addr %}
+{%   endif %}
 
-add rule ip nat {{ chain }} iifname "{{ iface }}" {{ src_addr }} {{ src_port }} {{ tcp_dst_port }} {{ dst_addr }} counter log prefix "{{ log }}" comment "{{ comment }}"
-{%     endif %}
-add rule ip nat {{ chain }} iifname "{{ iface }}" {{ src_addr }} {{ src_port }} {{ tcp_dst_port }} {{ dst_addr }} counter {{ trns_addr }}{{ trns_port }} comment "{{ comment }}"
-{%     if log %}
-add rule ip nat {{ chain }} iifname "{{ iface }}" {{ src_addr }} {{ src_port }} {{ udp_dst_port }} {{ dst_addr }} counter log prefix "{{ log }}" comment "{{ comment }}"
-{%     endif %}
-add rule ip nat {{ chain }} iifname "{{ iface }}" {{ src_addr }} {{ src_port }} {{ udp_dst_port }} {{ dst_addr }} counter {{ trns_addr }}{{ trns_port }} comment "{{ comment }}"
+{%   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 proto_dst_port = dst_port if dst_port else "ip protocol " + r.protocol %}
-{%       set proto_dst_port = "" if r.protocol == "all" %}
+{%     set output = output + " ip protocol " + protocol %}
+{%   endif %}
 
-{%     if log %}
-add rule ip nat {{ chain }} iifname "{{ iface }}" {{ src_addr }} {{ src_port }} {{ proto_dst_port }} {{ dst_addr }} counter log prefix "{{ log }}" comment "{{ comment }}"
-{%     endif %}
-add rule ip nat {{ chain }} iifname "{{ iface }}" {{ src_addr }} {{ src_port }} {{ proto_dst_port }} {{ dst_addr }} counter {{ trns_addr }}{{ trns_port }} comment "{{ comment }}"
+{#   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 %}