recpfilter.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 "recpheader.hh"
#include "recpfilter.hh"

CLICK_DECLS

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

RecpFilter::~RecpFilter()
{
}

int
RecpFilter::configure(Vector<String> &conf, ErrorHandler *errh)
{
  int ret = cp_va_parse(conf, this, errh,
			cpKeywords,
			"ETHTYPE", cpUnsigned, "Ethernet Recp 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
RecpFilter::push(int, 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;
  if (ethtype != htons(_et)) {
    output(0).push(p);
    return;
  }

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

  // has an recp header, try to separate that into another precpet
  struct click_enc_recp *recph = (struct click_enc_recp *)(eh + 1);
  
  uint8_t hlen = recph->get_hlen(recph->nentries());
  recph = (struct click_enc_recp*) malloc(hlen);
  memcpy(recph, (struct click_enc_recp*)(eh+1), hlen);
  int recplen = sizeof(click_ether) + hlen;

  WritablePacket *recppkt = Packet::make(recplen);
  if (!recppkt)
    return;

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

  memcpy(recppkt->data(), p->data(), recplen);
  output(1).push(recppkt);

  if (recph->_et_next == htons(_et_nothing)) return;  // a pure recp packet

  click_chatter("%s : pushing the data packet", id().cc()); 
  // sort out the original precpet too
  WritablePacket *wp = p->uniqueify();
  wp->pull(recplen);  // 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 = recph->_et_next;
  sa.clear();
  sa << "Source EA " << src << " Dst EA " << dst;
  click_chatter("%s data packet %s %#x", id().cc(), sa.c_str(), ntohs(recph->_et_next)); 
  output(0).push(wp);
}

CLICK_ENDDECLS
EXPORT_ELEMENT(RecpFilter)