ackfilter.cc

COPE the first practical network coding scheme which is developped on click

/*
 * ackfilter.{cc,hh} -- Picks up ack header for encoded packets
 * Wenjun Hu
 *
 * Copyright (c) 2005 University of Cambridge
 * Copyright (c) 2005 Massachusetts Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, subject to the conditions
 * listed in the Click LICENSE file. These conditions include: you must
 * preserve this copyright notice, and you cannot mention the copyright
 * holders in advertising related to the Software without their permission.
 * The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
 * notice is a summary of the Click LICENSE file; the license in that file is
 * legally binding.
 */

#include <click/config.h>
#include <click/confparse.hh>
#include <click/error.hh>
#include <click/glue.hh>
#include <click/etheraddress.hh>
#include <clicknet/ether.h>
#include <click/straccum.hh>
#include <click/timestamp.hh>
#include <click/string.hh>
#include "ackheader.hh"
#include "ackfilter.hh"
#include "../sr/srpacket.hh"
#include <click/ipaddress.hh>
#include <click/timestamp.hh>
#include <click/straccum.hh>
#include <click/packet_anno.hh>

CLICK_DECLS

AckFilter::AckFilter()
  : Element(1, 2),
    _et(0), _et_nothing(0)
{
}

AckFilter::~AckFilter()
{
}

int
AckFilter::configure(Vector<String> &conf, ErrorHandler *errh)
{
  int ret = cp_va_parse(conf, this, errh,
			cpKeywords,
			"ETHTYPE", cpUnsigned, "Ethernet Ack encapsulation type", &_et, 
			"NOTHINGETHTYPE", cpUnsigned, "Nothing Ethernet Encapsulation type", &_et_nothing, 
			cpEnd);

  if (!_et)
    return errh->error("ETHTYPE not specified");
  if (!_et_nothing)
    return errh->error("NOTHINGETHTYPE not specified");


  return ret;
}


void
AckFilter::push(int port, Packet *p)
{
  click_ether *eh = (click_ether *) p->data();
  EtherAddress src = EtherAddress(eh->ether_shost);
  EtherAddress dst = EtherAddress(eh->ether_dhost);
  uint16_t ethtype = eh->ether_type;
  click_chatter("%s packet length %d", id().cc(), p->length());
  if (ethtype != htons(_et)) {
    if (ntohs(ethtype) == 0x0943) {
      WritablePacket *pw = p->uniqueify();
  
      struct srpacket *pk = (struct srpacket *)(eh+1);
      int extra = pk->hlen_wo_data() + sizeof(click_ether);
  
      const click_ip *i = reinterpret_cast<const click_ip *>(pw->data()+extra);
      pw->set_ip_header(i, i->ip_hl << 2);
      StringAccum sa; 
      sa << EtherAddress(eh->ether_shost) << " " << IPAddress(i->ip_src) << " " << ntohs(i->ip_id) << " " << IPAddress(i->ip_dst);
      click_chatter("%s ackfilter %s", id().cc(), sa.c_str()); 
    }
    output(0).push(p);
    return;
  }

  click_chatter("ackfilter received a packet with ackheader and ethtype %04x at %u", ntohs(ethtype), Timestamp::now().msec1());

  // has an ack header, try to separate that into another packet
  struct click_enc_ack *ackh = (struct click_enc_ack *)(eh + 1);
  
  uint8_t hlen = ackh->get_hlen(ackh->nentries());
  ackh = (struct click_enc_ack*) malloc(hlen);
  memcpy(ackh, (struct click_enc_ack*)(eh+1), hlen);
  int acklen = sizeof(click_ether) + hlen;

  WritablePacket *ackpkt = Packet::make(acklen);
  if (!ackpkt)
    return;

  StringAccum sa;
  sa << "push() separating ack packet from ea " << EtherAddress(src);
  click_chatter("%s %s", id().cc(), sa.c_str());

  memcpy(ackpkt->data(), p->data(), acklen);
  output(1).push(ackpkt);

  if (ackh->_et_next == htons(_et_nothing)) return;  // a pure ack packet

  click_chatter("%s : pushing the data packet", id().cc()); 
  // sort out the original packet too
  WritablePacket *wp = p->uniqueify();
  wp->pull(acklen);  // not sure about this offset...***
  wp = wp->push(sizeof(click_ether));
  click_ether *oeth = (click_ether *)wp->data();
  memcpy(oeth->ether_dhost, dst.data(), 6);
  memcpy(oeth->ether_shost, src.data(), 6);
  oeth->ether_type = ackh->_et_next;
  sa.clear();
  sa << "Source EA " << src << " Dst EA " << dst;
  click_chatter("%s data packet %s %#x", id().cc(), sa.c_str(), ntohs(ackh->_et_next)); 
  output(0).push(wp);
}

CLICK_ENDDECLS
EXPORT_ELEMENT(AckFilter)