#!/usr/bin/env /usr/bin/plcsh
#
# Writes IP addresses and hostnames of PlanetLab nodes to
# /etc/plc_hosts. Useful for dnsmasq, specify "addn-hosts
# /etc/plc_hosts" in /etc/dnsmasq.conf.
#
# Mark Huang <mlhuang@cs.princeton.edu>
# Copyright (C) 2006 The Trustees of Princeton University
#
# pylint: disable=c0111

import sys
import os
from plc_config import PLCConfiguration

def writepid(prog):
    """
    Check PID file. Exit if already running. Update PID file.
    """

    try:
        with open("/var/run/%s.pid" % prog, "r") as pidfile:
            pid = pidfile.readline().strip()
        if os.path.isdir("/proc/" + pid):
            print("Error: Another copy of %s is still running (%s)" % (prog, pid))
            sys.exit(1)
    except IOError:
        pass

    with open("/var/run/%s.pid" % prog, "w") as pidfile:
        pidfile.write(str(os.getpid()))

def removepid(prog):
    os.unlink("/var/run/%s.pid" % prog)

def main():
    writepid("dns-config")

    cfg = PLCConfiguration()
    cfg.load()
    variables = cfg.variables()

    (_, variablelist) = variables['plc_dns']
    plc_dns = dict(list(zip(list(variablelist.keys()),
                            [variable['value']
                             for variable in list(variablelist.values())])))

    if plc_dns['enabled'] != "true":
        return 0

    # Get the primary IP address for each node
    hosts = {}

    nodes = {}
    for node in GetNodes():
        nodes[node['node_id']] = node

    interface_ids = set()
    for node in list(nodes.values()):
        interface_ids.update(node['interface_ids'])

    for interface in GetInterfaces(list(interface_ids)):
        if not interface['ip']:
            continue

        if interface['hostname']:
            hostname = interface['hostname']
        else:
            hostname = nodes[interface['node_id']]['hostname']

        if interface['ip'] in hosts:
            if hostname not in hosts[interface['ip']]:
                hosts[interface['ip']].append(hostname)
        else:
            hosts[interface['ip']] = [hostname]

    # Write /etc/plc_hosts
    plc_hosts = open("/etc/plc_hosts", "w")
    plc_hosts.write("# DO NOT EDIT; File is written and removed by automatic scripts\n")
    for ip, hostnames in hosts.items():
        plc_hosts.write(ip + "\t" + " ".join(hostnames) + "\n")
    plc_hosts.close()

    # From the default dnsmasq.conf configuration file:
    #
    # The [domain-needed and bogus-priv] options make you a better
    # netizen, since they tell dnsmasq to filter out queries which
    # the public DNS cannot answer, and which load the servers
    # (especially the root servers) uneccessarily.
    #
    with open("/etc/dnsmasq.conf", "w") as writer:
        writer.write("""
domain-needed
bogus-priv
addn-hosts=/etc/plc_hosts
resolv-file=/etc/resolv.conf
""".lstrip())

    # Reload dnsmasq
    os.system("killall -q -HUP dnsmasq")

    removepid("dns-config")

if __name__ == '__main__':
    main()