Merge pull request #485 from tiiuae/fix_avahi

Fix "IPv6 connection unreliable from external PC"

Author: joenpera

modules/sc-mesh-secure-deployment/src/nats/conf/default_ms_config.yaml

@@ -2,6 +2,9 @@
 # Mesh Shield config file #
 ###########################
 
+# hostname of the device
+hostname: nixos
+
 # All the interfaces are black by default.
 # Excluded interfaces or interfaces without macsec certificates are not added to lower CBMA.
 # White interfaces are added to upper CBMA and are excluded automatically from lower CBMA.

modules/sc-mesh-secure-deployment/src/nats/src/cbma_adaptation.py

@@ -22,6 +22,7 @@
 from src.interface import Interface
 from src import comms_config_store
 from src.bat_ctrl_utils import BatCtrlUtils
+from src.comms_service_refresh import CommsServiceRefresh
 
 from controller import CBMAController
 from models.certificates import CBMACertificates
@@ -85,6 +86,7 @@ def __init__(
         if self.__config is not None:
             self.__cbma_config = self.__config.read("CBMA")
             self.__vlan_config = self.__config.read("VLAN")
+            self.__hostname = self.__config.read("hostname")
 
         # Create VLAN interfaces if configured
         self.__create_vlan_interfaces()
@@ -106,6 +108,9 @@ def __init__(
                 self.__red_interfaces.extend(red_interfaces)
                 self.__na_cbma_interfaces.extend(exclude_interfaces)
 
+        self.__service_refresh = CommsServiceRefresh(self.__hostname, logger)
+        self.__service_thread = None
+
     def __validate_cbma_config(
         self,
         exclude_interfaces: List[str],
@@ -280,6 +285,24 @@ def __delete_vlan_interfaces(self) -> bool:
                 success = False
         return success
 
+    def __set_hostname(self) -> None:
+        """
+        Set hostname for device configured in ms_config.yaml.
+        """
+        try:
+            subprocess.run(["hostname", self.__hostname], check=True)
+        except subprocess.CalledProcessError as e:
+            self.logger.error(f"Error setting hostname {self.__hostname}: {e}")
+
+    def __update_avahi_hostname(self) -> None:
+        """
+        Update avahi hostname for device configured in ms_config.yaml.
+        """
+        try:
+            subprocess.run(["avahi-set-host-name", self.__hostname], check=True)
+        except subprocess.CalledProcessError as e:
+            self.logger.error(f"Error updating avahi hostname {self.__hostname}: {e}")
+
     def __get_interfaces(self) -> None:
         interfaces = []
         ip = IPRoute()
@@ -809,6 +832,10 @@ def setup_cbma(self) -> bool:
         :return: True if both lower and upper CBMA was setup
                  successfully. Returns False otherwise.
         """
+        # hostname updates
+        self.__set_hostname()
+        self.__update_avahi_hostname()
+
         self.__init_batman_and_bridge()
 
         self.__update_cbma_interface_lists()
@@ -841,6 +868,10 @@ def setup_cbma(self) -> bool:
         # Set batman hop penalty
         self.__batman.set_hop_penalty()
 
+        # Start the service publisher thread
+        self.__service_thread = threading.Thread(target=self.__service_refresh.dns_service_refresh)
+        self.__service_thread.start()
+
         return True
 
     def __is_valid_ipv6_local(self, address: tuple[str, int]) -> bool:
@@ -1090,4 +1121,8 @@ def stop_cbma(self) -> bool:
         self.__cleanup_cbma()
         self.stop_radios()
 
+        self.__service_refresh.shutdown_service()
+        if self.__service_thread is not None:
+            self.__service_thread.join()
+
         return lower_stopped and upper_stopped

modules/sc-mesh-secure-deployment/src/nats/src/comms_service_refresh.py

@@ -0,0 +1,50 @@
+"""
+Refresher class for the comms service registration
+"""
+import logging
+import threading
+import time
+import subprocess
+
+class CommsServiceRefresh:
+    """
+    Comms service publisher class
+    """
+    DNS_SERVICE_EVENT_LOOP_TIMEOUT: int = 5
+
+    def __init__(self, __hostname, __logger: logging.Logger) -> None:
+
+        self.logger: logging.Logger = __logger.getChild("CommsServicePublisher")
+        self.logger.setLevel(logging.INFO)
+        self.__event: threading.Event = threading.Event()
+        self.__hostname: str = __hostname
+
+
+    def __refresh_hostname(self) -> None:
+        """
+        Refresh the hostname with avahi-resolve-host-name
+        """
+        try:
+            subprocess.run(["avahi-resolve-host-name", self.__hostname + ".local"],
+                           check=True,
+                           stdout=subprocess.PIPE,
+                           stderr=subprocess.PIPE)
+        except subprocess.CalledProcessError:
+            self.logger.exception("Error refreshing hostname")
+
+    def dns_service_refresh(self) -> None:
+        """
+        Register and re-announce service periodically
+        """
+        self.logger.info("Refresh start")
+        while not self.__event.is_set():
+            time.sleep(self.DNS_SERVICE_EVENT_LOOP_TIMEOUT)
+            self.__refresh_hostname()
+        self.logger.info("Refresh stopped")
+
+
+    def shutdown_service(self) -> None:
+        """
+        Shutdown the service
+        """
+        self.__event.set()