#!/usr/bin/python
#
# 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
#
# $Id: api-config,v 1.10 2006/05/24 03:08:55 mlhuang Exp $
#

import plcapilib
(plcapi, moreopts, argv) = plcapilib.plcapi(globals())
from plc_config import PLCConfiguration
import os, sys

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

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

    pidfile = file("/var/run/%s.pid" % prog, "w")
    pidfile.write(str(os.getpid()))
    pidfile.close()

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

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

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

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

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

    # Get the primary IP address for each node
    hosts = {}
    nodes = AdmGetNodes([], ['node_id', 'hostname'])
    plcapi.begin()
    for node in nodes:
        AdmGetAllNodeNetworks(node['node_id'])
    nodenetworks_list = plcapi.commit()
    if nodenetworks_list is not None:
        for i, nodenetworks in enumerate(nodenetworks_list):
            for nodenetwork in nodenetworks:
                if nodenetwork['hostname']:
                    hostname = nodenetwork['hostname']
                else:
                    hostname = nodes[i]['hostname']
        
                if hosts.has_key(nodenetwork['ip']):
                    if hostname not in hosts[nodenetwork['ip']]:
                        hosts[nodenetwork['ip']].append(hostname)
                else:
                    hosts[nodenetwork['ip']] = [hostname]
    
    # Write /etc/plc_hosts
    plc_hosts = open("/etc/plc_hosts", "w")
    for ip, hostnames in hosts.iteritems():
        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.
    #
    file("/etc/dnsmasq.conf", "w").write("""
domain-needed
bogus-priv
addn-hosts=/etc/plc_hosts
""".lstrip())

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

    removepid("dns-config")

if __name__ == '__main__':
    main()