selfcheck.py: add network check

clever/src/selfcheck.py

@@ -9,6 +9,7 @@
 # The above copyright notice and this permission notice shall be included in all
 # copies or substantial portions of the Software.
 
+import os
 import math
 import subprocess
 import re
@@ -692,9 +693,32 @@ def check_preflight_status():
                 failure(' '.join([match.groups()[1], 'check:', check_status]))
 
 
+@check('Network')
+def check_network():
+    ros_hostname = os.environ.get('ROS_HOSTNAME').strip()
+
+    if not ros_hostname:
+        failure('No ROS_HOSTNAME is set')
+
+    elif ros_hostname.endswith('.local'):
+        # using mdns hostname
+        hosts = open('/etc/hosts', 'r')
+        for line in hosts:
+            parts = line.split()
+            if len(parts) < 2:
+                continue
+            ip = parts.pop(0).split('.')
+            if ip[0] == '127':  # loopback ip
+                if ros_hostname in parts:
+                    break
+        else:
+            failure('Not found %s in /etc/hosts, ROS will malfunction if network interfaces are down, https://clever.coex.tech/hostname', ros_hostname)
+
+
 def selfcheck():
     check_image()
     check_clever_service()
+    check_network()
     check_fcu()
     check_imu()
     check_local_position()