From d6e68aef7de1927e1ce31091cfab449f798be85b Mon Sep 17 00:00:00 2001
From: l_samenv <markus.zolliker@psi.ch>
Date: Wed, 6 Mar 2024 15:22:25 +0100
Subject: [PATCH] utils.MainIf: rename 'getip' to 'poll'

+ change mechanism for getting hostname
---
 display.py |  4 ++--
 utils.py   | 61 +++++++++++++++++++++++++++++++++---------------------
 2 files changed, 39 insertions(+), 26 deletions(-)

diff --git a/display.py b/display.py
index 821e2e3..ce0ce41 100644
--- a/display.py
+++ b/display.py
@@ -234,7 +234,7 @@ class Display:
             self.send(SET_COLOR, 0, 0, 0, 11 + self.blink)  # yellow / blue
             self.text('.', 0, dotpos, dotpos+1)
             self.color()
-            self.text(mainif.hostname or self.hostname, 1)
+            self.text(mainif.hostname() or self.hostname, 1)
             # self.event.set()
             self.blink = not self.blink
         else:
@@ -242,7 +242,7 @@ class Display:
             self.show('(cancel)(reboot)(shdown)')
 
     def refresh(self):
-        mainif.getip()
+        mainif.poll()
         func = self.menu or self.net_display
         func(self.gettouch())
 
diff --git a/utils.py b/utils.py
index d0d61b9..55200eb 100644
--- a/utils.py
+++ b/utils.py
@@ -45,12 +45,21 @@ def get_config(section=None):
     return result
 
 
+def gethostthread(ip, event, result):
+    try:
+        result[0] = socket.gethostbyaddr(ip)[0]
+    except Exception as e:
+        pass
+    event.set()
+
+
 class MainIf:
     address = None
     ip = None
     gateway = None
     hostname = None
     carrier = True
+    prev_ip = None
 
     def __init__(self):
         netcfg = get_config('NETWORK')
@@ -61,40 +70,44 @@ class MainIf:
         else:
             # take first one (alphabetically)
             self.name = sorted(netcfg)[0]
-        self.getip()
+        self.hostnameresult = [None]
+        with open(f'/sys/class/net/{self.name}/carrier_changes') as f:
+            self.carrier_changes = f.read()
+        self.poll()
 
-    def gethostthread(self, ip, event):
-        try:
-            hostname = socket.gethostbyaddr(ip)[0]
-            if event == self.event:
-                self.hostname = hostname
-        except Exception as e:
-            pass
-        event.set()
+    def hostname(self):
+        return self.hostnameresult[0]
 
-    def getip(self):
+    def poll(self):
         with open(f'/sys/class/net/{self.name}/carrier') as f:
             carrier = f.read().startswith('1')
-        if carrier != self.carrier:
+        with open(f'/sys/class/net/{self.name}/carrier_changes') as f:
+            carrier_changes = f.read()
+        if carrier_changes != self.carrier_changes:
+            self.hostnameresult = [None]  # new instance for result
+            self.carrier_changes = carrier_changes
             if carrier:
-                sudo(f'dhclient {self.name}')
-            else:
                 sudo(f'dhclient -r {self.name}')
+                sudo(f'dhclient {self.name}')
         self.carrier = carrier
         addrinfo = ifaddresses(self.name)
-        self.address = addrinfo.get(AF_LINK, [{}])[0].get('addr') 
+        self.address = addrinfo.get(AF_LINK, [{}])[0].get('addr')
         if carrier:
-            self.ip = addrinfo.get(AF_INET, [{}])[0].get('addr') 
-            self.gateway = gateways().get('default', {}).get(AF_INET) if self.ip else None
+            self.ip = addrinfo.get(AF_INET, [{}])[0].get('addr')
+            self.gateway = [g for g, n, _ in gateways().get(AF_INET, ()) if n == self.name]
         else:
             self.ip = None
-            self.gateway = None
-            self.hostname = None
+            self.gateway = ()
         if self.carrier and self.ip and self.gateway:
-            self.event = event = threading.Event()
-            result = []
-            threading.Thread(target=self.gethostthread, args=(self.ip, event), daemon=True).start()
-            event.wait(0.1)
+            if self.ip != self.prev_ip:
+                self.prev_ip = self.ip
+                self.event = event = threading.Event()
+                self.hostnameresult = list(self.hostnameresult)  # new instance for result
+                threading.Thread(target=gethostthread,
+                                 args=(self.ip, event, self.hostnameresult), daemon=True).start()
+                event.wait(0.1)
+                # in case of timeout, the thread may change self.hostnameresult later,
+                # but only until carrier or ip changes
         else:
-            self.event = None  # disable changing hostname from pending threads
-        return self.ip
+            self.prev_ip = None
+        return self.carrier, self.ip, self.hostnameresult[0], self.gateway