#!/usr/bin/env python
"""
Author: Bas van der Vlies <basv@sara.nl>
Date  : 12 February 2002
Desc. : This script is used to control how a node is booted with PXE
        enabled network cards. The PC boots starts and fetch a pxe
        config file which tells how the PC must boot. This daemon
        enables a client to remove his pxe-config file. It then uses
        the DEFAULT one. 
          
        Note:
          This server can ONLY be started from inetd.

CVS info
  $Date: 2002/02/18 15:02:00 $
  $Revision: 1.1 $
"""
import time
import socket
import sys
import os
import string
import syslog

# DEBUG
#
DEBUG=1

# Some Global Constants
#
BUFSIZE=4096
STDIN=0
STDOUT=1

PXE_CONF_DIR = '/tftpboot/pxelinux.cfg'

# Give the current time
#
def now():
    return time.ctime(time.time())


def remove_link(filename):
  """This removes the pxe config filename for the host that is connected:
      filename : string
  """

  file = os.path.join(PXE_CONF_DIR, filename)

  if DEBUG:
    print 'file = %s' %file

  if not os.path.exists(file): return

  if os.path.islink(file): 
    try:
      os.unlink(file)
      syslog.openlog("pxeconfigd")
      syslog.syslog(syslog.LOG_INFO, file)
      syslog.closelog()
    except OSError:
      err_msg = "No permission at directory: %s" %PXE_CONF_DIR
      os.write(STDOUT, err_msg)
      sys.exit(1)

# This function handles the client connection. It closes
# the connection if there is no data
#
def handleConnection():
  """Determines which host connects to the server
  """

  # Determine client address
  # 
  try:
    client_addr = socket.fromfd(sys.stdin.fileno(), socket.AF_INET, 
                          socket.SOCK_STREAM)
    client_ip = client_addr.getpeername()[0] 

  except socket.error, detail:
    print "pxeconfigd can only be started from inetd!!!"
    sys.exit(1)


  # translate ip address ---> hex address
  #
  d = string.split(client_ip, '.')
  client_haddr = '%02X%02X%02X%02X' %(int(d[0]), int(d[1]), int(d[2]), int(d[3]))

  if DEBUG:
    print 'ip = %s, hex = %s' %(client_ip, client_haddr)

  remove_link(client_haddr)
  sys.exit(0)


def server():
  """Start the daemon
  """

  if not os.path.isdir(PXE_CONF_DIR):
    os.write(STDOUT, "PXE booting is not configured")
    sys.exit(1)

  handleConnection()

if __name__ == '__main__':
  server()