wlb: T4470: Migrate WAN load balancer to Python/XML

data/templates/load-balancing/nftables-wlb.j2

@@ -0,0 +1,60 @@
+#!/usr/sbin/nft -f
+
+{% if first_install is not vyos_defined %}
+delete table ip vyos_wanloadbalance
+{% endif %}
+table ip vyos_wanloadbalance {
+    chain wlb_nat_postrouting {
+        type nat hook postrouting priority srcnat - 1; policy accept;
+{% for ifname, health_conf in interface_health.items() if health_state[ifname].if_addr %}
+{%     if disable_source_nat is not vyos_defined %}
+{%         set state = health_state[ifname] %}
+        ct mark {{ state.mark }} counter snat to {{ state.if_addr }}
+{%     endif %}
+{% endfor %}
+    }
+
+    chain wlb_mangle_prerouting {
+        type filter hook prerouting priority mangle; policy accept;
+{% for ifname, health_conf in interface_health.items() %}
+{%     set state = health_state[ifname] %}
+{%     if sticky_connections is vyos_defined %}
+        iifname "{{ ifname }}" ct state new ct mark set {{ state.mark }}
+{%     endif %}
+{% endfor %}
+{% for rule_id, rule_conf in rule.items() %}
+{%     if rule_conf.exclude is vyos_defined %}
+        {{ rule_conf | wlb_nft_rule(rule_id, exclude=True, action='accept') }}
+{%     else %}
+{%         set limit = rule_conf.limit is vyos_defined %}
+        {{ rule_conf | wlb_nft_rule(rule_id, limit=limit, weight=True, health_state=health_state) }}
+        {{ rule_conf | wlb_nft_rule(rule_id, restore_mark=True) }}
+{%     endif %}
+{% endfor %}
+    }
+
+    chain wlb_mangle_output {
+        type filter hook output priority -150; policy accept;
+{% if enable_local_traffic is vyos_defined %}
+        meta mark != 0x0 counter accept
+        meta l4proto icmp counter accept
+        ip saddr 127.0.0.0/8 ip daddr 127.0.0.0/8 counter accept
+{%     for rule_id, rule_conf in rule.items() %}
+{%         if rule_conf.exclude is vyos_defined  %}
+        {{ rule_conf | wlb_nft_rule(rule_id, local=True, exclude=True, action='accept') }}
+{%         else %}
+{%             set limit = rule_conf.limit is vyos_defined %}
+        {{ rule_conf | wlb_nft_rule(rule_id, local=True, limit=limit, weight=True, health_state=health_state) }}
+        {{ rule_conf | wlb_nft_rule(rule_id, local=True, restore_mark=True) }}
+{%         endif %}
+{%     endfor %}
+{% endif %}
+    }
+
+{% for ifname, health_conf in interface_health.items() %}
+{%     set state = health_state[ifname] %}
+    chain wlb_mangle_isp_{{ ifname }} {
+        meta mark set {{ state.mark }} ct mark set {{ state.mark }} counter accept
+    }
+{% endfor %}
+}

debian/control

@@ -205,9 +205,6 @@ Depends:
 # For "load-balancing reverse-proxy"
   haproxy,
 # End "load-balancing reverse-proxy"
-# For "load-balancing wan"
-  vyatta-wanloadbalance,
-# End "load-balancing wan"
 # For "service dhcp-relay"
   isc-dhcp-relay,
 # For "service dhcp-server"

python/vyos/template.py

@@ -779,6 +779,11 @@ def conntrack_ct_policy(protocol_conf):
 
     return ", ".join(output)
 
+@register_filter('wlb_nft_rule')
+def wlb_nft_rule(rule_conf, rule_id, local=False, exclude=False, limit=False, weight=None, health_state=None, action=None, restore_mark=False):
+    from vyos.wanloadbalance import nft_rule as wlb_nft_rule
+    return wlb_nft_rule(rule_conf, rule_id, local, exclude, limit, weight, health_state, action, restore_mark)
+
 @register_filter('range_to_regex')
 def range_to_regex(num_range):
     """Convert range of numbers or list of ranges

python/vyos/wanloadbalance.py

@@ -0,0 +1,133 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2024 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+
+from vyos.utils.process import run
+
+dhclient_lease = '/var/lib/dhcp/dhclient_{0}.lease'
+
+def nft_rule(rule_conf, rule_id, local=False, exclude=False, limit=False, weight=None, health_state=None, action=None, restore_mark=False):
+    output = []
+
+    if 'inbound_interface' in rule_conf:
+        ifname = rule_conf['inbound_interface']
+        if local and not exclude:
+            output.append(f'oifname != "{ifname}"')
+        elif not local:
+            output.append(f'iifname "{ifname}"')
+
+    if 'protocol' in rule_conf and rule_conf['protocol'] != 'all':
+        protocol = rule_conf['protocol']
+
+        if protocol == 'tcp_udp':
+            protocol = '{ tcp, udp }'
+
+        output.append(f'meta l4proto {protocol}')
+
+    for direction in ['source', 'destination']:
+        if direction not in rule_conf:
+            continue
+
+        direction_conf = rule_conf[direction]
+        prefix = direction[:1]
+
+        if 'address' in direction_conf:
+            operator = ''
+            address = direction_conf['address']
+            if address[:1] == '!':
+                operator = '!='
+                address = address[1:]
+            output.append(f'ip {prefix}addr {operator} {address}')
+
+        if 'port' in direction_conf:
+            operator = ''
+            port = direction_conf['port']
+            if port[:1] == '!':
+                operator = '!='
+                port = port[1:]
+            output.append(f'th {prefix}port {operator} {port}')
+
+    if 'source_based_routing' not in rule_conf and not restore_mark:
+        output.append('ct state new')
+
+    if limit and 'limit' in rule_conf and 'rate' in rule_conf['limit']:
+        output.append(f'limit rate {rule_conf["limit"]["rate"]}/{rule_conf["limit"]["period"]}')
+        if 'burst' in rule_conf['limit']:
+            output.append(f'burst {rule_conf["limit"]["burst"]} packets')
+
+    output.append('counter')
+
+    if restore_mark:
+        output.append('meta mark set ct mark')
+    elif weight:
+        weights, total_weight = wlb_weight_interfaces(rule_conf, health_state)
+        if len(weights) > 1: # Create weight-based verdict map
+            vmap_str = ", ".join(f'{weight} : jump wlb_mangle_isp_{ifname}' for ifname, weight in weights)
+            output.append(f'numgen random mod {total_weight} vmap {{ {vmap_str} }}')
+        elif len(weights) == 1: # Jump to single ISP
+            ifname, _ = weights[0]
+            output.append(f'jump wlb_mangle_isp_{ifname}')
+        else: # No healthy interfaces
+            return ""
+    elif action:
+        output.append(action)
+
+    return " ".join(output)
+
+def wlb_weight_interfaces(rule_conf, health_state):
+    interfaces = [(ifname, int(if_conf.get('weight', 1))) for ifname, if_conf in rule_conf['interface'].items() if health_state[ifname]['state']]
+
+    if not interfaces:
+        return [], 0
+
+    if 'failover' in rule_conf:
+        for ifpair in sorted(interfaces, key=lambda i: i[1], reverse=True):
+            return [ifpair], ifpair[1] # Return highest weight interface that is ACTIVE when in failover
+
+    total_weight = sum(weight for ifname, weight in interfaces)
+    out = []
+    start = 0
+    for ifname, weight in sorted(interfaces, key=lambda i: i[1]): # build weight ranges
+        end = start + weight - 1
+        out.append((ifname, f'{start}-{end}' if end > start else start))
+        start = weight
+
+    return out, total_weight
+
+def health_ping_host(host, ifname, count=1, wait_time=0):
+    cmd_str = f'ping -c {count} -W {wait_time} -I {ifname} {host}'
+    rc = run(cmd_str)
+    return rc == 0
+
+def health_ping_host_ttl(host, ifname, count=1, ttl_limit=0):
+    cmd_str = f'ping -c {count} -t {ttl_limit} -I {ifname} {host}'
+    rc = run(cmd_str)
+    return rc != 0
+
+def parse_dhcp_nexthop(ifname):
+    lease_file = dhclient_lease.format(ifname)
+
+    if not os.path.exists(lease_file):
+        return False
+
+    with open(lease_file, 'r') as f:
+        for line in f.readlines():
+            data = line.replace('\n', '').split('=')
+            if data[0] == 'new_routers':
+                return data[1].replace("'", '').split(" ")[0]
+
+    return None