#!/usr/bin/env python

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#

# (C) Copyright 2007 One Laptop Per Child

#

import commands, sys, syslog, os

def get_ip4_address(iface):

    import socket

    import fcntl

    import struct

    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

    fd = s.fileno()

    SIOCGIFADDR = 0x8915

    addr = fcntl.ioctl(fd, SIOCGIFADDR, struct.pack('256s', iface[:15]))[20:24]

    s.close()

    return socket.inet_ntoa(addr)

def get_hw_address(iface):

    import struct

    import fcntl

    import socket

    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

    fd = s.fileno()

    SIOCGIFHWADDR = 0x8927

    req = fcntl.ioctl(fd, SIOCGIFHWADDR, struct.pack('16s16s', iface, ''))

    s.close()

    ignore1, ignore2, addr_high, addr_low = struct.unpack('>16sHHL8x', req)

    addr = (long(addr_high)<<32) + addr_low

    b0 = addr & 0xFF

    b1 = (addr >> 8) & 0xFF

    b2 = (addr >> 16) & 0xFF

    b3 = (addr >> 24) & 0xFF

    b4 = (addr >> 32) & 0xFF

    b5 = (addr >> 40) & 0xFF

    return "%02X:%02X:%02X:%02X:%02X:%02X" % (b5, b4, b3, b2, b1, b0)

def set_anycast(mask, mesh_dev):

    commands.getstatusoutput('echo "%s" > /sys/class/net/%s/anycast_mask' % (mask, mesh_dev))

def ipt(args):

    (s, o) = commands.getstatusoutput("/sbin/iptables %s" % args)

    if (s != 0):

        syslog("Error executing iptables command '%s': %s" % (args, o))

def masq_start(extif, intif):

    os.system('echo "1" > /proc/sys/net/ipv4/ip_forward')

    os.system('echo "1" > /proc/sys/net/ipv4/ip_dynaddr')

    modules = ["ip_tables", "ip_conntrack", "ip_conntrack_ftp", "ip_conntrack_irc",

                "iptable_nat", "ip_nat_ftp", "ip_nat_irc"]

    os.system("/sbin/modprobe " + " ".join(modules))

    ipt("-P INPUT ACCEPT")

    ipt("-F INPUT")

    ipt("-P OUTPUT ACCEPT")

    ipt("-F OUTPUT")

    ipt("-P FORWARD DROP")

    ipt("-F FORWARD")

    ipt("-t nat -F")

    # FWD: Allow all connections OUT and only existing and related ones IN

    ipt("-A FORWARD -i %s -o %s -m state --state ESTABLISHED,RELATED -j ACCEPT" % (extif, intif))

    ipt("-A FORWARD -i %s -o %s -j ACCEPT" % (extif, intif))

    ipt("-A FORWARD -i %s -o %s -j ACCEPT" % (intif, extif))

    #ipt("-A FORWARD -j LOG")

    # Enabling SNAT (MASQUERADE) functionality on $EXTIF

    ipt("-t nat -A POSTROUTING -o %s -j MASQUERADE" % extif)

def masq_stop():

    ipt("-F INPUT")

    ipt("-F OUTPUT")

    ipt("-P FORWARD DROP")

    ipt("-F FORWARD")

    ipt("-F -t nat")

    # Delete all User-specified chains

    ipt("-X")

    # Reset all IPTABLES counters

    ipt("-Z")

def mpp_start(mesh_dev, primary_dev):

    dns_file = file('/etc/resolv.conf','r')

    dns_addresses = ""

    for line in dns_file.readlines():

        if len(line.split()) >= 2 and line.split()[0] == "nameserver":

            dns_addresses += line.split()[1] + ", "

    dns_addresses = dns_addresses[:len(dns_addresses) - 2]

    dns_file.close()

    mesh_ip4_addr = get_ip4_address(mesh_dev)

    if not mesh_ip4_addr or not len(mesh_ip4_addr):

        return

    primary_hw_addr = get_hw_address(primary_dev).lower()

    #copy parameters to the DHCP conf file

    dhcpd_conf_text = """#Custom DHCP daemon configuration file - XO as MPP

ddns-update-style interim;

# free the addresses quickly, clients ignore them anyway

default-lease-time      60;

max-lease-time          60;

option domain-name-servers %s;

# Ignore requests from ourselves.  Because the 8388's mesh interface has

# the same MAC address as the eth interface, dhclient gets confused

class "me" {

    match if hardware = 01:%s;

}

subnet 169.254.0.0 netmask 255.255.0.0 {

    pool {

        deny members of "me";

        option routers            %s;

        # range of link-local addresses, won't be used by XO's

        range 169.254.0.1  169.254.255.254;

    }

}

"""   % (dns_addresses, primary_hw_addr, mesh_ip4_addr)

    fd = open("/etc/dhcpd.conf","w")

    fd.write(dhcpd_conf_text)

    fd.flush()

    fd.close()

    masq_start(primary_dev, mesh_dev)

    # Start MPP functionality in mesh firmware

    set_anycast("0x2", mesh_dev)   # mask for xo-as-mpp

    # Tell dhcpd to only listen on the mesh interface

    fd = open("/etc/sysconfig/dhcpd", "w")

    fd.write('DHCPDARGS="%s"' % mesh_dev)

    fd.close()

    (s, o) = commands.getstatusoutput("service dhcpd restart")

def mpp_stop(mesh_dev, primary_dev):

    masq_stop()

    (s, o) = commands.getstatusoutput("service dhcpd stop")

    try:

        os.remove("/etc/sysconfig/dhcpd")

        os.remove("/etc/dhcpd.conf")

    except OSError, e:

        pass

    # Stop MPP functionality in mesh firmware

    set_anycast("0x0", mesh_dev)   # mask for off

def main():

    if len(sys.argv) < 4:

        sys.exit()

    mesh_dev = sys.argv[1]

    action = sys.argv[2]

    primary_dev = sys.argv[3]

    if action == "meshready":

        mpp_start(mesh_dev, primary_dev)

    elif action == "meshdown":

        mpp_stop(mesh_dev, primary_dev)    

if __name__ == "__main__":

    main()