Editing Csv File To Edit Subnets So There Is No Overlap In Ip Ranges (ipaddress Module In Python 3.3)

I have been trying to create a csv file that will change all the subnets and IP address ranges so none overlap. I have this file to start: Zone Name, IPStart, IPStop,Range,Source G

Solution 1:

Both of my issues were solved by reordering the if statements and correctly resetting the iterator. There continues to be issues with the code, but my questions here have been answered.

This is my current code and it works better:

import ipaddress
import csv
from csv import DictReader, DictWriter
from itertools import filterfalse

withopen(r'file1.csv', newline='') as fin3,\
     open(r'file2.csv', newline='') as fin4,\
     open(r'file3.csv', 'w', newline='') as fout3:


    read3 = DictReader(fin3) # fin 3 and 4 are copies of the same file
    read4 = DictReader(fin4)

    writenum3 = DictWriter(fout3, fieldnames=read3.fieldnames) 
    writenum3.writeheader()

    lst4=[] # To prevent duplicate linesfor line3 in read3:
        line3['Range']=ipaddress.ip_network(line3['Range']) # Convert IP ranges to ip network object
        fin4.seek(0) # Reset iterator
        read4 = DictReader(fin4) # Read again to prevent errorsfor line4 in read4:
            line4['Range']=ipaddress.ip_network(line4['Range']) # Convert IP ranges to ip network objectif line3 notin lst4: # To prevent duplicate linesif line3['Range'].overlaps(line4['Range']): # Tests for IP overlapif line3['Range'].netmask < line4['Range'].netmask: # To avoid "Not contained in" errors
                        lst=list(line3['Range'].address_exclude(line4['Range'])) # List of subnets excluding line4 subnetfor val in lst:
                            line3['Range']=val # New range
                            line3[' IPStart']=val.network_address #New net address
                            line3[' IPStop']=val.broadcast_address #New broadcast address
                            lst4.append(line3)
                            writenum3.writerow(line3) # Write lineselse:
                        lst4.append(line3)
                        writenum3.writerow(line3) # Write lineselse:
                    lst4.append(line3)
                    writenum3.writerow(line3) # Write lines