# Volatility
# Copyright (C) 2007-2013 Volatility Foundation
#
# This file is part of Volatility.
#
# Volatility 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.
#
# Volatility 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 Volatility.  If not, see <http://www.gnu.org/licenses/>.
#

"""
@author:       Andrew Case
@license:      GNU General Public License 2.0
@contact:      atcuno@gmail.com
@organization:
"""

import os
import volatility.debug as debug
import volatility.plugins.linux.common as linux_common
from volatility.plugins.linux.slab_info import linux_slabinfo

class linux_sk_buff_cache(linux_common.AbstractLinuxCommand):
    """Recovers packets from the sk_buff kmem_cache"""

    def __init__(self, config, *args, **kwargs):
        self.edir = None
        linux_common.AbstractLinuxCommand.__init__(self, config, *args, **kwargs)
        self._config.add_option('UNALLOCATED', short_option = 'u', default = False, help = 'Show unallocated', action = 'store_true')
        self._config.add_option('DUMP-DIR', short_option = 'D', default = None, help = 'output directory for recovered packets', action = 'store', type = 'str')

    def write_sk_buff(self, s):
        pkt_len = s.len

        # keep sane sized packets
        if 0 < pkt_len < 0x6400000:

            start = s.data

            data = self.addr_space.zread(start, pkt_len)

            fname = "{0:x}".format(s.obj_offset)
            fd = open(os.path.join(self.edir, fname), "wb")
            fd.write(data)
            fd.close()

            yield "Wrote {0:d} bytes to {1:s}".format(pkt_len, fname)

    def walk_cache(self, cache_name):
        cache = linux_slabinfo(self._config).get_kmem_cache(cache_name, self._config.UNALLOCATED, struct_name = "sk_buff")

        if not cache:
            return

        for s in cache:
            for msg in self.write_sk_buff(s):
                yield msg

    def calculate(self):
        linux_common.set_plugin_members(self)

        self.edir = self._config.DUMP_DIR

        if not self.edir:
            debug.error("No output directory given.")

        for msg in self.walk_cache("skbuff_head_cache"):
            yield msg

        for msg in self.walk_cache("skbuff_fclone_cache"):
            yield msg

    def render_text(self, outfd, data):

        for msg in data:
            outfd.write("{0:s}\n".format(msg))


