feat(ns8): add DNS server running check and disabled dns toggle (#16)

Co-authored-by: Davide Principi <[email protected]>

imageroot/actions/configure-module/10validate

@@ -63,3 +63,14 @@ if request["dhcp-server"]["enabled"]:
         agent.set_status('validation-failed')
         json.dump([{'field':'dhcp-server.start', 'parameter':'dhcp-server.start','value': request['dhcp-server']['start'], 'error':'must_be_less_than_end'}], fp=sys.stdout)
         sys.exit(2)
+
+if request["dns-server"]["enabled"]:
+    is_dns_bound = network.are_ports_53_bound()
+    # 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"]
+    # check if dns is already bound to port 53 and stop the action
+    if is_dns_bound and not is_dns_enabled:
+        agent.set_status('validation-failed')
+        json.dump([{'field':'dnsEnableField', 'parameter':'dnsEnableField', 'value': request['dns-server']['enabled'], 'error':'dns_port_already_bind'}], fp=sys.stdout)
+        sys.exit(3)

imageroot/actions/get-configuration/10get

@@ -18,4 +18,10 @@ 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"]
+
 json.dump(config, sys.stdout)

imageroot/actions/get-configuration/validate-output.json

@@ -96,11 +96,21 @@
                 "primary-server",
                 "secondary-server"
             ]
+        },
+        "is_dns_enabled": {
+            "description": "True if dnsmasq is configured",
+            "type": "boolean"
+        },
+        "is_dns_bound": {
+            "description": "True if DNS servers are bound to the interface",
+            "type": "boolean"
         }
     },
     "required": [
         "interface",
         "dhcp-server",
-        "dns-server"
+        "dns-server",
+        "is_dns_enabled",
+        "is_dns_bound"
     ]
 }

imageroot/pypkg/network.py

@@ -8,6 +8,7 @@
 import ipaddress
 import json
 import subprocess
+import socket
 
 
 def __filter_interface(interface):
@@ -59,3 +60,21 @@ def list_interfaces():
     """
     subprocess_result = subprocess.run(["ip", "-4", "-j", "addr"], check=True, capture_output=True)
     return [__format_interface(interface) for interface in json.loads(subprocess_result.stdout) if __filter_interface(interface)]
+
+def __is_port_bound(port, protocol, ip='127.0.0.1'):
+    """
+    Check if a port is already bound for a given protocol (TCP/UDP) on a specific IP address.
+    """
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM if protocol == 'tcp' else socket.SOCK_DGRAM)
+    try:
+        s.bind((ip, port))
+        s.close()
+        return False
+    except OSError:
+        return True
+
+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)

ui/public/i18n/en/translation.json

@@ -53,7 +53,9 @@
         "dhcp-server_invalid_type": "Number required",
         "dhcp-server_number_gte": "Enter a positive number",
         "dns-server_format": "IPv4 format required",
-        "dns-server_number_one_of": "IPv4 or IPv6 required"
+        "dns-server_number_one_of": "IPv4 or IPv6 required",
+        "dns_server_is_running": "A DNS server is currently running",
+        "dns_server_is_running_description": "You cannot enable the DNS feature because a DNS server is already active on this node. Another application, such as Samba DC, might be using the DNS port."
     },
     "dns_records": {
         "title": "DNS records",

ui/src/views/Settings.vue

@@ -162,11 +162,28 @@
                 <div class="title-description mg-bottom-xlg">
                   {{ $t("settings.DNS_description") }}
                 </div>
+                <cv-row
+                  v-if="is_dns_bound && !dnsEnableField && !is_dns_enabled"
+                >
+                  <cv-column>
+                    <NsInlineNotification
+                      kind="info"
+                      :title="$t('settings.dns_server_is_running')"
+                      :description="
+                        $t('settings.dns_server_is_running_description')
+                      "
+                      :showCloseButton="false"
+                    />
+                  </cv-column>
+                </cv-row>
                 <NsToggle
                   :label="$t('settings.DNS_enable_label')"
                   v-model="dnsEnableField"
                   value="dnsEnableField"
                   formItem
+                  :disabled="
+                    is_dns_bound && !dnsEnableField && !is_dns_enabled
+                  "
                   ref="dnsEnableField"
                 >
                   <template slot="text-left">{{
@@ -201,7 +218,9 @@
                   :icon="Save20"
                   :loading="loading.configureModule"
                   :disabled="
-                    loading.getConfiguration || loading.configureModule
+                    loading.getConfiguration ||
+                    loading.configureModule ||
+                    (is_dns_bound && !dnsEnableField && !is_dns_enabled)
                   "
                   >{{ $t("settings.save") }}</NsButton
                 >
@@ -250,6 +269,8 @@ export default {
       dhcpStartField: "",
       dhcpEndField: "",
       dhcpLeaseField: 12,
+      is_dns_bound: false,
+      is_dns_enabled: false,
       dnsEnableField: false,
       dnsPrimaryField: "",
       dnsSecondaryField: "",
@@ -406,6 +427,8 @@ export default {
       this.dnsEnableField = dns_server["enabled"];
       this.dnsPrimaryField = dns_server["primary-server"];
       this.dnsSecondaryField = dns_server["secondary-server"];
+      this.is_dns_bound = config["is_dns_bound"];
+      this.is_dns_enabled = config["is_dns_enabled"];
     },
     validateConfigureModule() {
       this.clearErrors(this);