Python Script to Produce Difference Between Files and Resolve DNS Query for the Outpu

[sultan]

I wanted to write a python script that gives me the difference between two txt files that contain list of domains.

Below is my script that I was able to create.

import difflib

file1 = open("2.txt").readlines()
file2 = open("diff.txt").readlines()
with open ('diff.txt', 'w', encoding = 'UTF8') as diff:
	for line in difflib.unified_diff(file2,file1,n=0):
		for prefix in ('---','+++','@@'):
			if line.startswith(prefix):
				break
		if line.startswith('+'):
			diff.write("New DNS Entry:\n{}\n".format(line[1:]))
		elif line.startswith('-'):
			diff.write("Removed DNS Entry:\n{}\n".format(line[1:]))

Since unified_diff produces context and characters like +++, --- & @@, I have modified my code to omit this and disabled context.

The output I receive from the above code is as follows:

Output:
Removed DNS Entry:
-- 

New DNS Entry:
++ 

Removed DNS Entry:
example.com

As seen above, the output titles anything with a - as "Removed DNS Entry" and anything with a + as "New DNS Entry" and stops at very first iteration of a line change between two txt files (although there are multiple changes beyond example.com)

The output I'm expecting is that any line that starts with a + should be grouped together and titled "New DNS Entries" and similarly any line that starts with - should be grouped together and titled "Removed DNS Entries"

Eventually, the group of "New DNS Entries" should display their appropriate DNS resolutions.

Something like this..

Output:
New DNS Entries:
example1.com
example2.com

Removed DNS Entries:
example13.com
example21.com

DNS Resolution for new entries:

example1.com CNAME example.aws.com
example2.com A     192.168.1.1

Any help here is much appreciated!