#!/usr/bin/python2
# Vsys script to set a device in promisc mode
# The user needs to have the device allocated to him
# via the vsys_vnet tag. Set vsys_vnet to the IP address of
# the device. 
#
# From the slice:
# cat > /vsys/promisc.in
# vif312
# ^D
# 
# To disable promisc mode:
#
# cat > /vsys/promisc.in
# vif312
# -
# ^D
#
# (Notice the - on a newline)


import sys
import pwd
import re
import socket
import struct
import os
import string
import fcntl

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

def get_ip_address(ifname):
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    return socket.inet_ntoa(fcntl.ioctl(
        s.fileno(),
        0x8915,  # SIOCGIFADDR
        struct.pack('256s', ifname[:15])
    )[20:24])

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

slicename=sys.argv[1]
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
arglines = map(string.strip, sys.stdin.readlines())

if len(arglines)<1:
    print >>sys.stderr, "Insufficient argument lines."
    sys.exit(1)

vif = arglines[0] # interface name

if (len(arglines)==2 and arglines[1]=='-'):
    neg = True
else:
    neg = False

vip = get_ip_address(vif)


# 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)

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)

# OK. All checks passed. We can now act on the device.

if (not neg):
    os.system('ifconfig %s promisc'%vif)
else:
    os.system('ifconfig %s -promisc'%vif)