tuna: Replace python_ethtool with builtin funtionality

This patch replaces the dependency on python_ethtool with some
simplified functions to achieve the same result.

Reviewed-by: Federico Pellegrin <fede@evolware.org>
- return 'tun' only if tun_flags exists
Signed-off-by: John Kacur <jkacur@redhat.com>
diff --git a/tuna-cmd.py b/tuna-cmd.py
index 9a3d3f3..b13b25b 100755
--- a/tuna-cmd.py
+++ b/tuna-cmd.py
@@ -26,7 +26,7 @@
 import gettext
 import locale
 from functools import reduce
-import ethtool
+import tuna.new_eth as ethtool
 import tuna.tuna_sched as tuna_sched
 import procfs
 from tuna import tuna, sysfs
diff --git a/tuna/gui/irqview.py b/tuna/gui/irqview.py
index 35fc3fd..5143d6d 100755
--- a/tuna/gui/irqview.py
+++ b/tuna/gui/irqview.py
@@ -7,7 +7,7 @@
 from gi.repository import GObject
 import os
 from functools import reduce
-import ethtool
+import tuna.new_eth as ethtool
 import tuna.tuna_sched as tuna_sched
 
 import gi
diff --git a/tuna/new_eth.py b/tuna/new_eth.py
new file mode 100755
index 0000000..98f9179
--- /dev/null
+++ b/tuna/new_eth.py
@@ -0,0 +1,37 @@
+# Copyright (C) 2022 John Kacur
+""" A few functions similar to ethtool """
+import os
+import socket
+
+def get_active_devices():
+    """ return a list of network devices """
+    ret = []
+
+    for device in socket.if_nameindex():
+        ret.append(device[1])
+
+    return ret
+
+def get_module(intf):
+    """ return the kernel module for the given network interface """
+    if intf == 'lo':
+        return ""
+    myp = f'/sys/class/net/{intf}/device/driver'
+    if os.path.exists(myp):
+        return os.path.basename(os.readlink(myp))
+    if os.path.exists(f'/sys/class/net/{intf}/bridge'):
+        return 'bridge'
+    if os.path.exists(f'/sys/class/net/{intf}/tun_flags'):
+        return 'tun'
+    return ""
+
+if __name__ == "__main__":
+    nics = get_active_devices()
+    print(f'nics = {nics}')
+
+    for intf in nics:
+        driver = get_module(intf)
+        if driver:
+            print(f'{intf}, {driver}')
+        else:
+            print(f'{intf}')
diff --git a/tuna/tuna.py b/tuna/tuna.py
index 30a5a57..43adb84 100755
--- a/tuna/tuna.py
+++ b/tuna/tuna.py
@@ -9,7 +9,7 @@
 import shlex
 import fnmatch
 import platform
-import ethtool
+import tuna.new_eth as ethtool
 import procfs
 from procfs import utilist
 from tuna import help