Looping through multiple regex efficiently

Question

I'm writing a program that adds all network interfaces with multiple parameters to a list.

I have written the following code, which should work out of the box on any Linux system with Python and ethtool installed:

import imp
import os
import subprocess
import re
from enum import Enum 


class interface_type(Enum):

    OPTIC = 1
    TWISTED_PAIR = 2


class NetworkInterface:

    def set_indentifier(self, id):
        self.id = id

    def set_mac_address(self, mac):
        self.mac = mac

    def set_interface_type(self, interface_type):
        self.interface_type = interface_type


def findNetworkInterfaces(ignoredInterface):

    filteredList = netifaces.interfaces()
    network_interfaces = []

    for interface in filteredList:
        for regex in ignoredInterface:
            if re.search(regex, interface):
                break
            else:
                nwi = NetworkInterface()
                nwi.set_indentifier(interface)
                nwi.set_mac_address(setMAC(interface))
                nwi.set_interface_type(setInterfaceType(interface))
                network_interfaces.append(nwi)
                filteredList.remove(interface)
                break
    return network_interfaces


def setMAC(identifier):

    addrs = netifaces.ifaddresses(identifier)
    mac_address = addrs[netifaces.AF_LINK][0].get("addr")

    return mac_address


def setInterfaceType(identifier):

    bashCommand1 = "ethtool " + identifier 
    bashCommand2 = "grep ports"

    try:
        process1 = subprocess.Popen(bashCommand1.split(), 
            stdout=subprocess.PIPE)
        process2 = subprocess.Popen(bashCommand2.split(), 
            stdin=process1.stdout, stdout=subprocess.PIPE)
        output, error = process2.communicate()

    except:
        print ("Error determining interface type: " + error + "\n")
        print ("Interface will be treated as Optical \n")

    if "TP" in output:
        return interface_type.TWISTED_PAIR
    else: 
        return interface_type.OPTIC


if __name__ == "__main__":

    ignored_interface = ["lo", "wlp2s0"]

    try:
        imp.find_module("netifaces")
        netifaces_status = True
        import netifaces

    except ImportError as e:
        print ("netifaces not found: " + str(e))
        os.sys.exit(-1)

    network_identifiers = findNetworkInterfaces(ignored_interface)

    #print network_identifiers

    for iface in network_identifiers:
        print iface.id
        print iface.mac
        print iface.interface_type

I'm mainly concerned with the findNetworkInterfaces function, as I feel I'm doing this in a very ineffecient way (basically copying the list and removing interfaces as to not have doubles). In this special case, I'm not concerned with PEP8 - this is something I'll do later. Any other suggestions to improve the code are very welcome.

Ludisposed · Accepted Answer · 2019-01-21 20:25:20Z

Start writing in python3.x ;)

End of Life for python2.x will happen pretty soon 1
One regex to rule them all

Instead of looping over a the list to create a regex,

you could use the | char which will work as an or so it can handle multiple outputs

REGEX_FILTER = re.conmpile('lo|wlp2s0')
If you only need the parameters, a simple namedtuple will suffice

You could create a namedtuple that will get rid of the empty looking class
IMHO setting the variables outside of the init is bad style

I would get the different variables needed before, and only then create the NetworkInterface object.

Note I will not review getting the interface type, since I am nowhere near a linux atm

Code

from collections import namedtuple
import re

import netifaces

FILTER_REGEX = re.compile(r'lo|wlp2s0')
NetworkInterface = namedtuple('NetworkInterface', ['iface', 'mac', 'type'])

def get_mac(iface):
    addresses = netifaces.ifaddresses(iface)
    return addresses[netifaces.AF_LINK][0].get("addr")

def get_type(iface):
    """Just return TP for testing"""
    return "TP"

def find_network_interfaces():
    for iface in netifaces.interfaces():
        if FILTER_REGEX.search(iface):
            continue
        yield NetworkInterface(iface, get_mac(iface), get_type(iface))

if __name__ == '__main__':
    for nwi in find_network_interfaces():
        print(nwi.iface)
        print(nwi.mac)
        print(nwi.type)

Since you saved the compiled regexes to a variable, you could do FILTER_REGEX.search(iface). — Graipher
– Graipher, Commented Jan 21, 2019 at 18:58

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