#!/usr/bin/python
# VSYS script to configure per-slice virtual network interfaces from the root slice
#   Thom Haddow - 06/10/09
#
# Gets slice name as argv[1]
# Takes remaining args on stdin:
#   - Interface name (eg [tun|tap]<sliceid>-<n>)
#   - IP address (eg 1.2.3.4)
#   - Netmask (as int, e.g. 24)

import sys
import pwd
import re
import socket
import struct
import os

vsys_config_dir = "/etc/planetlab/vsys-attributes"

if len(sys.argv) != 2: sys.exit(1)

# VSYS scripts get slicename as $1
slicename=sys.argv[1]
sliceid = pwd.getpwnam(slicename).pw_uid

netblock_config=os.path.join(vsys_config_dir,slicename,"vsys_vnet")

# Read netblock allocation file
base = None

for netblock in open(netblock_config,'r'):
    base, mask = netblock.split('/')

if base is None:
    print >>sys.stderr, "Could not find entry for slice %s in netblock config file %s" % (slicename, netblock_config)
    sys.exit(1)


### Read args from stdin
vif = sys.stdin.readline().strip() # interface name
vip = sys.stdin.readline().strip() # IP
vmask = int(sys.stdin.readline().strip()) # netmask as int

# TODO further config args? txqueue, nat? Can add these later...



# Convert network base addr to int format by unpacking as 32bit net-ordered long (!L)
base_int = struct.unpack('!L',socket.inet_aton(base))[0]
mask = int(mask)


### Validate args
# Validate interface name
if len(vif)>16:
    print >>sys.stderr, "Interface name %s invalid"%(vif)
    sys.exit(1)

if re.match(r'(tun|tap)%d-\d+' % sliceid, vif ) is None:
    print >>sys.stderr, "Interface name %s does not match slice id %d."%(vif, sliceid)
    sys.exit(1)



# Validate requested IP and convert to int format.
try:
    vip_int = struct.unpack('!L',socket.inet_aton(vip))[0]
except socket.error:
    print >>sys.stderr, "Invalid IP: %s" % vip
    sys.exit(1)

# Check IP is in netblock
if (vip_int>>(32-mask)) != (base_int>>(32-mask)):
    print >>sys.stderr, "Requested IP %s not in netblock %s/%d" % (vip,base,mask)
    sys.exit(1)

# TODO. Check IP is not in use?

# Validate mask: Check requested mask is sane and within our netblock
if vmask>32 or vmask <8:
    print >>sys.stderr, "Requested netmask /%d is invalid" %(vmask)
    sys.exit(1)
    
if vmask<mask:
    print >>sys.stderr, "Requested netmask /%d larger than allocation /%d" %(vmask, mask)
    sys.exit(1)



### Configure interface

cmd_ifconfig = "/sbin/ifconfig %s %s/%d" % (vif, vip, vmask)
os.system(cmd_ifconfig)

# Add iptables rules (Clearing old ones first, if they exist)
cmd_iptables_in = "/sbin/iptables -A INPUT -i %s -m mark ! --mark %d -j DROP" % (vif, sliceid)
cmd_iptables_del_in = "/sbin/iptables -D INPUT -i %s -m mark ! --mark %d -j DROP 2>/dev/null" % (vif, sliceid)
cmd_iptables_out = "/sbin/iptables -A OUTPUT -o %s -m mark ! --mark %d -j DROP" % (vif, sliceid)
cmd_iptables_del_out = "/sbin/iptables -D OUTPUT -o %s -m mark ! --mark %d -j DROP 2>/dev/null" % (vif, sliceid)

os.system(cmd_iptables_del_in)
os.system(cmd_iptables_in)
os.system(cmd_iptables_del_out)
os.system(cmd_iptables_out)