Merge pull request #21 from NethServer/feat-7210

Inhibit DNS service if Samba is installed

Refs NethServer/dev#7210

container/dnsmasq.conf

@@ -2,7 +2,7 @@
 
 # container related configuration
 keep-in-foreground
-log-facility=/dev/stdout
+log-facility=-
 cache-size=4000
 
 # DNS

imageroot/actions/configure-module/10validate

@@ -65,7 +65,7 @@ if request["dhcp-server"]["enabled"]:
         sys.exit(2)
 
 if request["dns-server"]["enabled"]:
-    is_dns_bound = network.are_ports_53_bound()
+    is_dns_bound = network.are_ports_53_bound() or bool(network.get_local_samba_dcs())
     # read config.json and determine if dns is used for this instance
     config = json.load(open("config.json"))
     is_dns_enabled = config["dns-server"]["enabled"]

imageroot/actions/configure-module/20configure

@@ -7,29 +7,11 @@
 
 import json
 import sys
+import agent
 
 request = json.load(sys.stdin)
 
 # write dnsmasq configuration to easy json file, will be used by UI
 open("config.json", "w").write(json.dumps(request))
 
-# convert json to configuration file
-with open("dnsmasq.d/00config.conf", "w") as file:
-    file.write("# This file is automatically generated by NethServer, manual changes will be lost.\n")
-    # write interface only if dhcp-server or dns-server are enabled
-    if request["dhcp-server"]["enabled"] or request["dns-server"]["enabled"]:
-        file.write("interface=" + request["interface"] + "\n")
-
-    # write dhcp-server configuration
-    if request["dhcp-server"]["enabled"]:
-        file.write("dhcp-range=set:default," + request["dhcp-server"]["start"] + "," + request["dhcp-server"]["end"] + "," + str(request["dhcp-server"]["lease"]) + "h\n")
-
-    # write dns-server configuration
-    if request["dns-server"]["enabled"]:
-        file.write("server=" + request["dns-server"]["primary-server"] + "\n")
-        if request["dns-server"]["secondary-server"] != "":
-            file.write("server=" + request["dns-server"]["secondary-server"] + "\n")
-
-    else:
-        # shut down dns server if not enabled
-        file.write("port=0\n")
+agent.run_helper('expand-config').check_returncode()

imageroot/actions/create-module/20default_config

@@ -6,22 +6,9 @@
 #
 
 import json
+import agent
 
-config = {
-    "interface": "",
-    "dhcp-server": {
-        "enabled": False,
-        "start": "",
-        "end": "",
-        "lease": 12
-    },
-    "dns-server": {
-        "enabled": False,
-        "primary-server": "",
-        "secondary-server": ""
-    },
-}
-
-open("config.json", "w").write(json.dumps(config))
+# Force the initialization of config.json for get-configuration:
+agent.run_helper('expand-config').check_returncode()
 
 open("dns-records.json", "w").write(json.dumps({"records": []}))

imageroot/actions/get-configuration/10get

@@ -7,7 +7,7 @@
 
 import json
 import sys
-
+import agent
 import network
 
 config = json.load(open("config.json"))
@@ -18,10 +18,16 @@ if config["interface"] != "" and config["dhcp-server"]["start"] == "" and config
     config["dhcp-server"]["start"] = str(interface["start"])
     config["dhcp-server"]["end"] = str(interface["end"])
 
-# we test if tcp/53 or udp/53 is bound to the interface
-config["is_dns_bound"] = network.are_ports_53_bound()
-# check if dnsmasq is enabled in the configuration, needed to determine in the UI if the DNS server was enabled and used by dnsmasq.
-# the dnsmasq service is always running, we cannot state if it is enabled/active or not.
-config['is_dns_enabled'] = config["dns-server"]["enabled"]
+# we test if tcp/53 or udp/53 is bound to the interface, or local Samba DCs are present
+local_samba_dcs = network.get_local_samba_dcs()
+if len(local_samba_dcs) > 0:
+    config["is_dns_bound"] = True
+    config["is_dns_enabled"] = False
+    config["dns-server"]["enabled"] = False
+else:
+    config["is_dns_bound"] = network.are_ports_53_bound()
+    # check if dnsmasq is enabled in the configuration, needed to determine in the UI if the DNS server was enabled and used by dnsmasq.
+    # the dnsmasq service is always running, we cannot state if it is enabled/active or not.
+    config['is_dns_enabled'] = config["dns-server"]["enabled"]
 
 json.dump(config, sys.stdout)

imageroot/bin/expand-config

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+
+#
+# Copyright (C) 2024 Nethesis S.r.l.
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+
+import json
+import sys
+import agent
+import network
+
+# Read configuration from a JSON file or initialize it.
+try:
+    config = json.load(open("config.json"))
+except FileNotFoundError:
+    print(agent.SD_NOTICE, "Generating a new config.json file...", file=sys.stderr)
+    config = {
+        "interface": "",
+        "dhcp-server": {
+            "enabled": False,
+            "start": "",
+            "end": "",
+            "lease": 12
+        },
+        "dns-server": {
+            "enabled": False,
+            "primary-server": "",
+            "secondary-server": ""
+        },
+    }
+    json.dump(config, fp=open("config.json", "w"))
+
+
+# Lookup local Samba DCs. They want to bind DNS port 53 like us.
+local_samba_dcs = network.get_local_samba_dcs()
+
+# convert json to configuration file
+with open("dnsmasq.d/00config.conf", "w") as file:
+    file.write("# This file is automatically generated by NethServer, manual changes will be lost.\n")
+    # write interface only if dhcp-server or dns-server are enabled
+    if config["dhcp-server"]["enabled"] or config["dns-server"]["enabled"]:
+        file.write("interface=" + config["interface"] + "\n")
+
+    # write dhcp-server configuration
+    if config["dhcp-server"]["enabled"]:
+        file.write("dhcp-range=set:default," + config["dhcp-server"]["start"] + "," + config["dhcp-server"]["end"] + "," + str(config["dhcp-server"]["lease"]) + "h\n")
+
+    # write dns-server configuration, if no local Samba DC is present
+    if len(local_samba_dcs) > 0:
+        print("Local Active Directory DC found, DNS feature is blocked.", local_samba_dcs, file=sys.stderr)
+        file.write("port=0\n")
+    elif config["dns-server"]["enabled"]:
+        file.write("server=" + config["dns-server"]["primary-server"] + "\n")
+        if config["dns-server"]["secondary-server"] != "":
+            file.write("server=" + config["dns-server"]["secondary-server"] + "\n")
+    else:
+        # shut down dns server if not enabled
+        file.write("port=0\n")

imageroot/dnsmasq.service

@@ -8,19 +8,19 @@ RequiresMountsFor=%t/containers
 [Service]
 Environment=PODMAN_SYSTEMD_UNIT=%n
 EnvironmentFile=/var/lib/nethserver/%N/state/environment
-Restart=on-failure
+Restart=always
 TimeoutStopSec=70
 ExecStartPre=/bin/rm \
         -f %t/%n.ctr-id
 ExecStartPre=runagent -m %N reload_hosts
+ExecStartPre=runagent -m %N expand-config
 ExecStart=/usr/bin/podman run \
         --cidfile=%t/%n.ctr-id \
         --cgroups=no-conmon \
         --rm \
         --sdnotify=conmon \
-        -d \
-        --replace \
-        --name=dnsmasq \
+        --detach \
+        --replace --name=%N \
         --network=host \
         --cap-add=NET_ADMIN,NET_RAW \
         --volume=/var/lib/nethserver/%N/state/dnsmasq.d:/etc/dnsmasq.d:Z \

imageroot/events/module-added/10restart_dnsmasq

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+#
+# Copyright (C) 2024 Nethesis S.r.l.
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+
+import json
+import os
+import sys
+import agent
+
+data = json.load(sys.stdin)
+
+# skip if the event comes from another node
+if os.environ['NODE_ID'] != str(data['node']):
+    sys.exit(0)
+
+agent.run_helper('systemctl', 'try-restart', os.getenv('MODULE_ID'))

imageroot/events/module-removed/10restart_dnsmasq

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+#
+# Copyright (C) 2024 Nethesis S.r.l.
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+
+import json
+import os
+import sys
+import agent
+
+data = json.load(sys.stdin)
+
+# skip if the event comes from another node
+if os.environ['NODE_ID'] != str(data['node']):
+    sys.exit(0)
+
+agent.run_helper('systemctl', 'try-restart', os.getenv('MODULE_ID'))

imageroot/pypkg/network.py

@@ -5,6 +5,9 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 #
 
+import sys
+import os
+import agent
 import ipaddress
 import json
 import subprocess
@@ -78,3 +81,18 @@ def are_ports_53_bound(ip='127.0.0.1'):
     Check if both TCP and UDP ports 53 are bound on a specific IP address.
     """
     return __is_port_bound(53, 'tcp', ip) or __is_port_bound(53, 'udp', ip)
+
+def get_local_samba_dcs():
+    """
+    Lookup Samba modules installed on the local node. Returns an array of
+    Samba module IDs that were installed on the local node. Typically the
+    array has 1 element at most.
+    """
+    rdb = agent.redis_connect(use_replica=True)
+    local_samba_dcs = []
+    for module_id, node_id in rdb.hgetall("cluster/module_node").items():
+        if node_id != os.environ["NODE_ID"]:
+            continue
+        if module_id.startswith('samba'):
+            local_samba_dcs.append(module_id)
+    return local_samba_dcs