def getbans()

in blocky-client.py [0:0]
78 lines of code
17 McCabe index (conditional complexity)

def getbans(chain='INPUT'):
    """ Gets a list of all bans in a chain """
    banlist = []

    # Get IPv4 list
    for i in range(0, MAX_IPTABLES_TRIES):
        out = None
        try:
            out = subprocess.check_output([ENV_EXEC, IPTABLES_EXEC, '--list', chain, '-n', '--line-numbers'],
                                          stderr=subprocess.STDOUT)
        except subprocess.CalledProcessError as err:
            if 'you must be root' in str(err.output) or 'Permission denied' in str(err.output):
                print("Looks like blocky doesn't have permission to access iptables, giving up completely! (are you "
                      "running as root?)")
                sys.exit(-1)
            if 'No chain/target/match' in str(err.output):
                continue
            time.sleep(1)  # write lock, probably
        if out:
            for line in out.decode('ascii').split("\n"):
                m = re.match(r"^(\d+)\s+([A-Z]+)\s+(all|tcp|udp)\s+(\S+)\s+([0-9a-f.:/]+)\s+([0-9a-f.:/]+)\s*(.*?)$",
                             line)
                if m:
                    ln = m.group(1)
                    action = m.group(2)
                    protocol = m.group(3)
                    option = m.group(4)
                    source = m.group(5)
                    destination = m.group(6)
                    extensions = m.group(7)

                    entry = {
                        'chain': chain,
                        'linenumber': ln,
                        'action': action,
                        'protocol': protocol,
                        'option': option,
                        'source': source,
                        'asNet': netaddr.IPNetwork(source),
                        'destination': destination,
                        'extensions': extensions,
                    }

                    banlist.append(entry)
            break
    # Get IPv6 list
    if not os.path.exists(IP6TABLES_EXEC):
        return banlist
    for i in range(0, MAX_IPTABLES_TRIES):
        try:
            out = subprocess.check_output([ENV_EXEC, IP6TABLES_EXEC, '--list', chain, '-n', '--line-numbers'],
                                          stderr=subprocess.STDOUT)
        except subprocess.CalledProcessError as err:
            if 'you must be root' in str(err.output):
                print("Looks like blocky doesn't have permission to access iptables, giving up completely! (are you "
                      "running as root?)")
                sys.exit(-1)
            if 'No chain/target/match' in str(err.output):
                continue
            time.sleep(1)  # write lock, probably
        if out:
            for line in out.decode('ascii').split("\n"):
                # Unlike ipv4 iptables, the 'option' thing is blank here, so omit it
                m = re.match(r"^(\d+)\s+([A-Z]+)\s+(all|tcp|udp)\s+([0-9a-f.:/]+)\s+([0-9a-f.:/]+)\s*(.*?)$", line)
                if m:
                    ln = m.group(1)
                    action = m.group(2)
                    protocol = m.group(3)
                    source = m.group(4)
                    destination = m.group(5)
                    extensions = m.group(6)

                    entry = {
                        'chain': chain,
                        'linenumber': ln,
                        'action': action,
                        'protocol': protocol,
                        'option': '---',
                        'source': source,
                        'asNet': netaddr.IPNetwork(source),
                        'destination': destination,
                        'extensions': extensions,
                    }

                    banlist.append(entry)
            break
    return banlist