<reponame>Mahdi-Asaly/Coursera-SDN-Assignments
# Copyright 2012 <NAME>
#
# This file is part of POX.
#
# POX 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 3 of the License, or
# (at your option) any later version.
#
# POX 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 POX.  If not, see <http://www.gnu.org/licenses/>.

from pox.lib.addresses import *
import pox.lib.packet as pkt

from struct import pack
import time


class SocketWedge (object):
  def __init__ (self, socket):
    self._socket = socket

  def send (self, string, *args, **kw):
    r = self._socket.send(string, *args, **kw)
    self._send_out(string, r)
    return r

  def recv (self, bufsize, *args, **kw):
    r = self._socket.recv(bufsize, *args, **kw)
    self._recv_out(r)
    return r

  def __getattr__ (self, n):
    return getattr(self._socket, n)


class PCapWriter (object):
  def __init__ (self, outstream, socket = None, flush = False,
                local_addrs = (None,None,None),
                remote_addrs = (None,None,None)):
    """
    outstream is the stream to write the PCAP trace to.
    Ethernet addresses have to be faked, and it can be convenient to
    fake IP and TCP addresses as well.  Thus, you can specify local_addrs
    or remote_addrs.  These are tuples of (EthAddr, IPAddr, TCPPort).
    Any item that is None gets a default value.
    """
    self._out = outstream
    self._flush = flush

    if socket is not None:
      remote = socket.getpeername()
      local = socket.getsockname()
    else:
      remote = ("1.1.1.1",1)
      local = ("0.0.0.0",0)

    def create_packet (e1,e2,i1,i2,t1,t2):
      e = pkt.ethernet(
          src = e1,
          dst = e2,
          type = pkt.ethernet.IP_TYPE)
      i = pkt.ipv4(
          srcip = i1,
          dstip = i2,
          protocol = pkt.ipv4.TCP_PROTOCOL)
      t = pkt.tcp(
          srcport = t1,
          dstport = t2,
          off = 5,
          win = 1)
      t.ACK = True
      i.payload = t
      e.payload = i
      return e

    self._c_to_s = create_packet(
      local_addrs[0] or EthAddr("\x02" + "\x00" * 5),
      remote_addrs[0] or EthAddr("\x02" + "\x11" * 5),
      local_addrs[1] or IPAddr(local[0]),
      remote_addrs[1] or IPAddr(remote[0]),
      local_addrs[2] or local[1],
      remote_addrs[2] or remote[1],
      )

    self._s_to_c = create_packet(
      remote_addrs[0] or EthAddr("\x02" + "\x11" * 5),
      local_addrs[0] or EthAddr("\x02" + "\x00" * 5),
      remote_addrs[1] or IPAddr(remote[0]),
      local_addrs[1] or IPAddr(local[0]),
      remote_addrs[2] or remote[1],
      local_addrs[2] or local[1],
      )

    outstream.write(pack("IHHiIII",
      0xa1b2c3d4,    # Magic
      2,4,           # Version
      time.timezone, # TZ offset
      0,             # Accuracy of timestamps (apparently 0 is OK)
      0x7fffFFff,    # Snaplen
      1              # Ethernet
      ))

  def write (self, outgoing, buf):
    if len(buf) == 0: return
    e = self._c_to_s if outgoing else self._s_to_c
    e2 = self._c_to_s if not outgoing else self._s_to_c
    l = len(buf)
    e.payload.payload.payload = buf
    buf = e.pack()

    t = time.time()
    ut = t - int(t)
    t = int(t)
    ut = int(ut * 1000000)
    self._out.write(pack("IIII",
      t,ut,          # Timestamp
      len(buf),      # Saved size
      len(buf),      # Original size
      ))

    self._out.write(buf)
    if self._flush: self._out.flush()

    e.next.next.seq += l
    e2.next.next.ack += l


class CaptureSocket (SocketWedge):
  """
  Wraps a TCP socket and writes a faked PCAP format trace
  """
  def __init__ (self, socket, outstream, close = True,
                local_addrs = (None,None,None),
                remote_addrs = (None,None,None)):
    """
    socket is the socket to be wrapped.
    outstream is the stream to write the PCAP trace to.
    Ethernet addresses have to be faked, and it can be convenient to
    fake IP and TCP addresses as well.  Thus, you can specify local_addrs
    or remote_addrs.  These are tuples of (EthAddr, IPAddr, TCPPort).
    Any item that is None gets a default value.
    """
    super(CaptureSocket, self).__init__(socket)
    self._close = close
    self._writer = PCapWriter(outstream, socket=socket,
                              local_addrs=local_addrs,
                              remote_addrs=remote_addrs)


  def _recv_out (self, buf):
    try:
      self._writer.write(False, buf)
    except Exception:
      pass

  def _send_out (self, buf, r):
    try:
      self._writer.write(True, buf[:r])
    except Exception:
      pass

  def close (self, *args, **kw):
    if self._close:
      try:
        self._writer._out.close()
      except Exception:
        pass
    return self._socket.close(*args, **kw)


if __name__ == "__main__":
  """
  Test with:
  nc -v -v -l 9933
  """
  import socket
  sock = socket.create_connection(("127.0.0.1",9933))
  s = CaptureSocket(sock, file("test.pcap", "w"))
  while True:
    d = s.recv(1024)
    d = d.upper()
    import sys
    import time
    import random
    time.sleep(random.random() * 1.5)
    sys.stdout.write(d)
    s.send(d)

