#!/usr/bin/env python3

import sys
import os
import re
import socket
import xml.etree.ElementTree as etree

hosts_xml = "/opt/etc/hosts.xml"
dhcp_hosts = "/etc/dhcp/dhcpd.hosts"
ipset_entries = "/etc/iptables/ipset.entries"

bool_flags = ['service', 'voip', 'ext']

def err_msg(msg):
    sys.stderr.write("Fail: " + str(msg) + "\n")
    sys.exit(-1)

# getting attributes of hosts
def get_hosts(root):
    hosts = []
    for item in root.iter('host'):
        host = {}
        # main attributes
        try:
            host['name'] = item.attrib['name']
            host['ip'] = item.attrib['ip']
            host['mac'] = item.attrib['mac'].lower()
        except KeyError as key:
            print("Next host does't have attribute ", key, ":", sep="")
            etree.dump(item)
            continue
        # check IP address
        try:
            socket.inet_aton(host['ip'])
        except socket.error:
            print("This host has a incorrectly value of a IP address:")
            etree.dump(item)
            continue
        # check MAC address
        if not (re.match("[0-9a-f]{2}([-:][0-9a-f]{2}){5}$", host['mac'])):
            print("This host has a incorrectly value of a MAC address:")
            etree.dump(item)
            continue
        # other attributes
        host['mac_wifi'] = item.attrib.get('mac_wifi', '').lower()
        if ((not (re.match("[0-9a-f]{2}([-:][0-9a-f]{2}){5}$", host['mac_wifi'])))
            and (host['mac_wifi'] != '')):
            print("This host has a incorrectly value of a MAC Wi-Fi address:")
            etree.dump(item)
        host['desc'] = item.attrib.get('desc', 'Unknow')
        # boolean attributes
        for attrib in bool_flags:
            attrib_value = item.attrib.get(attrib, 'false').lower()
            if attrib_value not in ['true', 'false']:
                print("This host has a incorrectly value attribute '", attrib, "':", sep="")
                etree.dump(item)
            host[attrib] = (attrib_value == 'true')
        hosts.append(host)
    return hosts

def get_dhcp_host(name, ip, mac, desc):
    return ("host "+ name + " { # " + desc + "\n"
            "    hardware ethernet " + mac + ";\n"
            "    fixed-address " + ip + ";\n"
            "}\n")

if  __name__ == "__main__":

    try:
        tree = etree.parse(hosts_xml)
        dhcp_f = open(dhcp_hosts, 'w')
        ipset_f = open(ipset_entries, 'w')
    except IOError as error:
        err_msg(error)

    hosts = get_hosts(tree.getroot())

    # sorting by IP
    for host in sorted(hosts, key=lambda host: socket.inet_aton(host['ip'])):

        # write hosts in dhcp.hosts and ipset.entries
        dhcp_f.write(get_dhcp_host(host['name'], host['ip'], host['mac'], host['desc']))
        ipset_f.write("# " + host['desc'] + "\n")
        ipset_f.write("add check_mac " + host['ip'] + "," + host['mac'] + "\n")
        if (host['mac_wifi'] != ''):
            dhcp_f.write(get_dhcp_host(host['name'] + "-wifi", host['ip'], host['mac_wifi'], host['desc'] + " wifi"))
            ipset_f.write("add check_mac_wifi " + host['ip'] + "," + host['mac_wifi'] + "\n")
        for flag in bool_flags:
            if (host[flag]): ipset_f.write("add " + flag + " " + host['ip'] + "\n")
        ipset_f.write("\n")

    dhcp_f.close()
    ipset_f.close()

    # reload dhcpd and ipset
    os.system("/etc/init.d/isc-dhcp-server restart")
    os.system("/usr/sbin/ipset flush")
    os.system("/usr/sbin/ipset restore < " + ipset_entries)