syslog-ng python function to unwrap e-mail addresses rewritten with SRS

sender_rewriting_scheme.py

import re

def unwrap(message, address):
    address = address.decode("utf-8")
    result = re.search(r"\ASRS0=[^=]+=[^=]+=(?P<domain_name>[^=]+)=(?P<local_part>[^@]+)@", address)

    if result == None:
        result = re.search(r"\ASRS1=[^=]+=[^=]+==[^=]+=[^=]+=(?P<domain_name>[^=]+)=(?P<local_part>[^@]+)@", address)

    if result == None:
        return address

    return "{0}@{1}".format(result['local_part'], result['domain_name'])

test_sender_rewriting_scheme.py

import pytest

from sender_rewriting_scheme import unwrap

def test_srs_unwrap():
    assert unwrap(None, b'alice@example.org') == 'alice@example.org'
    assert unwrap(None, b'SRS0=HHH=TT=example.org=alice@example.com') == 'alice@example.org'
    assert unwrap(None, b'SRS1=HHH=example.com==HHH=TT=example.org=alice@example.net') == 'alice@example.org'