Parsing output txt "show ip route" to csv - python-3.6

Question

I need to use python code to parse a text file with the output of the routing table from several routers (I will provide an example of a text file). I want to get a structure in which the title or the first column with the name of the router goes and then the parameters (routing protocol, network, mask, AD, nexthop, time). But with the name of the router I can’t.
This is a text file to parse:
..................THIS IS THE HOST IP ADDRESS...................
192.168.100.1
R1>show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
90.0.0.0/24 is subnetted, 11 subnets
B 90.1.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.2.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.3.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.4.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.5.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.6.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.7.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.8.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.9.0.0 [20/0] via 192.168.100.2, 15:02:50
B 90.10.0.0 [20/0] via 192.168.100.2, 15:02:50
--More-- B 90.11.0.0 [20/0] via 192.168.100.2, 15:02:50
192.168.100.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.100.0/24 is directly connected, FastEthernet0/0
L 192.168.100.1/32 is directly connected, FastEthernet0/0
R1>
..................THIS IS THE HOST IP ADDRESS...................
192.168.100.2
R2>show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
90.0.0.0/24 is subnetted, 11 subnets
S 90.1.0.0 is directly connected, Null0
S 90.2.0.0 is directly connected, Null0
S 90.3.0.0 is directly connected, Null0
S 90.4.0.0 is directly connected, Null0
S 90.5.0.0 is directly connected, Null0
S 90.6.0.0 is directly connected, Null0
S 90.7.0.0 is directly connected, Null0
S 90.8.0.0 is directly connected, Null0
S 90.9.0.0 is directly connected, Null0
S 90.10.0.0 is directly connected, Null0
--More-- S 90.11.0.0 is directly connected, Null0
192.168.100.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.100.0/24 is directly connected, FastEthernet0/0
L 192.168.100.2/32 is directly connected, FastEthernet0/0
R2>
..................THIS IS THE HOST IP ADDRESS...................
192.168.100.3
R3>show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
192.168.100.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.100.0/24 is directly connected, FastEthernet0/0
L 192.168.100.3/32 is directly connected, FastEthernet0/0
R3>
This is the result in the CSV that I get:
protocol,network,mask,AD,nextHop,interface,time
B,90.1.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.2.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.3.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.4.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.5.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.6.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.7.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.8.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.9.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.10.0.0,,[20/0],192.168.100.2,,02:47:13
B,90.11.0.0,,[20/0],192.168.100.2,,02:47:13
C,192.168.100.0,24,,is directly connected,FastEthernet0/0,
L,192.168.100.1,32,,is directly connected,FastEthernet0/0,
S,90.1.0.0,,,is directly connected,Null0,
S,90.2.0.0,,,is directly connected,Null0,
S,90.3.0.0,,,is directly connected,Null0,
S,90.4.0.0,,,is directly connected,Null0,
S,90.5.0.0,,,is directly connected,Null0,
S,90.6.0.0,,,is directly connected,Null0,
S,90.7.0.0,,,is directly connected,Null0,
S,90.8.0.0,,,is directly connected,Null0,
S,90.9.0.0,,,is directly connected,Null0,
S,90.10.0.0,,,is directly connected,Null0,
S,90.11.0.0,,,is directly connected,Null0,
C,192.168.100.0,24,,is directly connected,FastEthernet0/0,
L,192.168.100.2,32,,is directly connected,FastEthernet0/0,
C,192.168.100.0,24,,is directly connected,FastEthernet0/0,
L,192.168.100.3,32,,is directly connected,FastEthernet0/0,
C,192.168.100.0,24,,is directly connected,FastEthernet0/0,
L,192.168.100.3,32,,is directly connected,FastEthernet0/0,
The result that I want to get:
device,protocol,network,mask,AD,nextHop,interface,time
R1,B,90.1.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.2.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.3.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.4.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.5.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.6.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.7.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.8.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.9.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.10.0.0,,[20/0],192.168.100.2,,02:47:13
R1,B,90.11.0.0,,[20/0],192.168.100.2,,02:47:13
R1,C,192.168.100.0,24,,is directly connected,FastEthernet0/0,
R1,L,192.168.100.1,32,,is directly connected,FastEthernet0/0,
R2,S,90.1.0.0,,,is directly connected,Null0,
R2,S,90.2.0.0,,,is directly connected,Null0,
R2,S,90.3.0.0,,,is directly connected,Null0,
R2,S,90.4.0.0,,,is directly connected,Null0,
R2,S,90.5.0.0,,,is directly connected,Null0,
R2,S,90.6.0.0,,,is directly connected,Null0,
R2,S,90.7.0.0,,,is directly connected,Null0,
R2,S,90.8.0.0,,,is directly connected,Null0,
R2,S,90.9.0.0,,,is directly connected,Null0,
R2,S,90.10.0.0,,,is directly connected,Null0,
R2,S,90.11.0.0,,,is directly connected,Null0,
R2,C,192.168.100.0,24,,is directly connected,FastEthernet0/0,
R2,L,192.168.100.2,32,,is directly connected,FastEthernet0/0,
R3,C,192.168.100.0,24,,is directly connected,FastEthernet0/0,
R3,L,192.168.100.3,32,,is directly connected,FastEthernet0/0,
This is my code
from collections import ChainMap
import csv
import re
regex_device = re.compile('(?P<Router>^.+)[>#]')
regex = re.compile('(?P<protocol>\S+) +'
'(?P<network>\d+\.\d+\.\d+\.\d+)/?'
'(?P<mask>\d*) +'
'(?P<AD>\[\d+/\d+\]) +via +'
'(?P<nextHop>\d+\.\d+\.\d+\.\d+)\,\ +'
'(?P<interface>\S+\d+/\d+)*'
'(?P<time>\S+)')
regex_direktly = re.compile('(?P<protocol>[L|C|S]) +'
'(?P<network>\d+\.\d+\.\d+\.\d\d?\d?)/?'
'(?P<mask>\d*) +'
'(?P<nextHop>.*), +'
'(?P<interface>\S+\d/\d+|.*)'
'(?P<time>\S*)')
result = []
result1 = []
with open('output_route_table.txt') as data:
for line in data:
match = regex_device.search(line)
if match:
result1.append(match.groupdict())
with open('output_route_table.txt') as data:
for line in data:
match = regex.search(line)
if match:
result.append(match.groupdict())
with open('output_route_table.txt') as data:
for line in data:
match = regex_direktly.search(line)
if match:
result.append(match.groupdict())
with open('output_route_table.csv', 'a') as f:
writer = csv.DictWriter(f, fieldnames=list(result[0].keys()))
writer.writeheader()
for d in result:
writer.writerow(d)

Answer 1

with open('output_route_table.txt') as data:
for line in data:
match = regex_device.search(line)
if match:
result1.append(match.groupdict())
with open('output_route_table.txt') as data:
for line in data:
match = regex.search(line)
if match:
result.append(match.groupdict())
with open('output_route_table.txt') as data:
for line in data:
match = regex_direktly.search(line)
if match:
result.append(match.groupdict())
This parts opens the file 3 times and first one scrapes the router names... to a list you never use. You need to go through the file only once and save the last router you saw (routes belong to the last router mentioned so far).
last_router = ""
with open('output_route_table.txt') as data:
for line in data:
is_router = regex_device.search(line)
if is_router:
last_router = is_router.group('Router') # get the name of the router only
is_route = regex.search(line) or regex_direktly.search(line) # gets first non-None value or None if all are None
if is_route:
result.append({'device': last_router, **is_route.groupdict()})