src: replace DEVICE env variable with get_ethernet_interface()

Use a python function to obtain the main net interface. Detect
the first ethernet inferface in use.
Stop using the DEVICE environment variable.

1 files changed, 67 insertions, 0 deletions

diff --git a/src/utils/net.py b/src/utils/net.py
index 01c6f04..e842c0f 100644
--- a/src/utils/net.py
+++ b/src/utils/net.py
@@ -10,6 +10,73 @@ import array
 import fcntl
 import socket
 import struct
+import psutil
+import logging
+
+def is_ethernet(interface):
+    SIOCGIFHWADDR = 0x8927
+    ARPHRD_ETHER = 1
+
+    try:
+        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        info = fcntl.ioctl(
+            s.fileno(),
+            SIOCGIFHWADDR,
+            struct.pack('256s', interface.encode('utf-8')[:15]))
+        if struct.unpack('H', info[16:18])[0] == ARPHRD_ETHER:
+            return True
+        return False
+    except IOError:
+        return False
+    finally:
+        s.close()
+
+def is_wifi(interface):
+    SIOCGIWNAME = 0x8B01  # Wireless-specific ioctl
+
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    try:
+        buffer = struct.pack('256s', interface.encode('utf-8'))
+        info = fcntl.ioctl(sock.fileno(), SIOCGIWNAME, buffer)
+        return True
+    except IOError:
+        return False
+    finally:
+        sock.close()
+
+def is_link_active(interface):
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+
+    try:
+        # Get interface flags
+        ifreq = struct.pack('16sh', interface.encode('utf-8'), 0)
+        flags = struct.unpack('16sh', fcntl.ioctl(sock.fileno(), 0x8913, ifreq))[1]
+
+        # Check if IFF_UP and IFF_RUNNING flags are set
+        if flags & 0x1 and flags & 0x40:
+            return True
+        else:
+            return False
+    except IOError:
+        return False
+    finally:
+        sock.close()
+
+def get_ethernet_interface():
+    eth_interfaces = []
+    interfaces = psutil.net_if_addrs()
+    for interface in interfaces:
+        if is_ethernet(interface) and not is_wifi(interface) and is_link_active(interface):
+            eth_interfaces.append(interface)
+
+    if len(eth_interfaces) > 1:
+        logging.info(f'Multiple active ethernet interfaces found: {", ".join(eth_interfaces)}. Using {eth_interfaces[0]}')
+
+    if not eth_interfaces:
+        logging.info('No valid ethernet interface found')
+        return None
+
+    return eth_interfaces[0]
 
 def ethtool(interface):
     try: