Find Python Linux Route Table

Question

I sent Python to find the first network hop about trying to find the first jump, and the more I thought about it, the easier it would be to do it. routing table in python. I am not a programmer, I do not know what I am doing .: P

This is what I came up with, the first problem I noticed is that the loopback interface does not appear in the / proc / net / route file, so a rating of 127.0.0.0/8 will give you the default route. for my application this does not matter.

Anything else important that I don't notice? Is it ip route get <ip>even better?

import re
import struct
import socket

'''
   Read all the routes into a list. Most specific first.
   # eth0  000219AC        04001EAC        0003    0       0       0       00FFFFFF ...
'''
def _RtTable():
    _rt = []
    rt_m = re.compile('^[a-z0-9]*\W([0-9A-F]{8})\W([0-9A-F]{8})[\W0-9]*([0-9A-F]{8})')
    rt = open('/proc/net/route', 'r')
    for line in rt.read().split('\n'):
        if rt_m.match(line):
            _rt.append(rt_m.findall(line)[0])

    rt.close()
    return _rt

'''
   Create a temp ip (tip) that is the entered ip with the host 
   section striped off.  Matching to routers in order, 
   the first match should be the most specific.

   If we get 0.0.0.0 as the next hop, the network is likely(?) 
   directly attached- the entered IP is the next (only) hop
'''
def FindGw(ip):
    int_ip = struct.unpack("I", socket.inet_aton(ip))[0]
    for entry in _RtTable():
        tip = int_ip & int(entry[2], 16)
        if tip == int(entry[0], 16):
            gw_s = socket.inet_ntoa(struct.pack("I", int(entry[1], 16)))
            if gw_s == '0.0.0.0':
                return ip
            else:
                return gw_s

if __name__ == '__main__':
    import sys
    print FindGw(sys.argv[1])

Answer 1

The proc file system manual page indicates that.

   /proc/net
          various net pseudo-files, all of which give the status of some part of
          the networking layer.  These files contain ASCII structures and  are,
          there‐fore, readable with cat(1).
          However, the standard netstat(8) suite provides much 
          cleaner access to these files.

, . netstat, traceroute . , .

Answer 2

pyroute2.IPRoute, , - 8.8.8.8:

from pyroute2 import IPRoute

with IPRoute() as ipr:
    print(ipr.route('get', dst='8.8.8.8'))