ovhdpkts.cc

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

#include <click/config.h>
#include <click/confparse.hh>
#include <click/error.hh>
#include <click/glue.hh>
#include <click/timestamp.hh>

#include <clicknet/ether.h>
#include <elements/wifi/sr/srpacket.hh>

#include "ovhdpkts.hh"
#include "xorheader_general.hh"

CLICK_DECLS

OverheardPackets::OverheardPackets()
  : Element(1, 1),  _enc_ethtype(0)
{
  click_chatter("init overheard packets");
}

OverheardPackets::~OverheardPackets()
{
}

void *
OverheardPackets::cast(const char *n)
{
  if (strcmp(n, "OverheardPackets") == 0)
    return (OverheardPackets *) this;
  else
    return 0;
}

int
OverheardPackets::configure(Vector<String> &conf, ErrorHandler *errh)
{
  click_chatter("starting overheard packets");
  int res;


  res = cp_va_parse(conf, this, errh,
		    cpKeywords, 
        "ETH", cpEtherAddress, "Ethernet address", &_myea,
        "ENCETHTYPE", cpUnsigned, "Ethtype for encoded packets", &_enc_ethtype,
        "LISTENMGR", cpElement, "Listen Manager for opp listening", &_listenmgr,
        "SCRAMBLEQ", cpElement, "Scramble Queue for timers", &_scrambleq,
        "GUESSMGR", cpElement, "Guess Manager", &_guessmgr,
		    cpEnd);

  if (!_myea)
    return errh->error("ETH not specified");

  if (!_enc_ethtype) {
    return errh->error("ENCETHTYPE not specified");
  }

  if (!_listenmgr) {
    return errh->error("LISTENMGR not specified");
  }
  if (_listenmgr->cast("ListenManager") == 0) {
    return errh->error("LISTENMGR element is not a ListenManager");
  }

  if (!_scrambleq) {
    return errh->error("SCRAMBLEQUEUE not specified");
  }
  if (_scrambleq->cast("ScrambleQueue") == 0) {
    return errh->error("SCRAMBLEQUEUE element is not a ScrambleQueue");
  }

  if (!_guessmgr) {
    return errh->error("GUESSMGR not specified");
  }
  if (_guessmgr->cast("GuessManager") == 0) {
    return errh->error("GUESSMGR element is not a GuessManager");
  }

  click_chatter("overheard packets done");
  return res;
}

  
void 
OverheardPackets::fwd_packet(Packet *p)
{
  if (p->packet_type_anno()!=Packet::OTHERHOST) {
    output(0).push(p);
    return; // packets are always new
  }
  else {
    struct click_ether *eth_p = (click_ether *)p->data();
    EtherAddress src = EtherAddress(eth_p->ether_shost);
    EtherAddress dst = EtherAddress(eth_p->ether_dhost);
    uint16_t et = ntohs(eth_p->ether_type);
    if (et == _enc_ethtype) {
      click_chatter("encoded and dropped");
    }
    StringAccum sa;
    sa << src << " " << dst << " " << et;
    click_chatter("%s: dropping a packet %s", id().cc(), sa.c_str());
    p->kill();
    return;
  }
}
 

//downstream element pushes packets to listenmanager
void
OverheardPackets::push(int, Packet *p)
{
  // there seem to be 4 bytes at the end, we will take them out now
  p->take(4);

  click_chatter("%s packet of length %d", id().cc(), p->length());
  int now = Timestamp::now().msec1();
  
  // Check if encoded packet
  struct click_ether *eth_p = (click_ether *)p->data();
  EtherAddress src = EtherAddress(eth_p->ether_shost);
  EtherAddress dst = EtherAddress(eth_p->ether_dhost);
  uint16_t et = ntohs(eth_p->ether_type);

  if (et == _enc_ethtype) {
    struct click_xorn_header *xorh = (struct click_xorn_header *)(eth_p + 1);
    int nentries = xorh->nentries();
    for (int i = 0; i < nentries; i++) {
      IPAddress ip_t = IPAddress(xorh->get_entry_src(i));
      uint16_t ipid_t = xorh->get_entry_ipid(i);
      _guessmgr->register_guess_single(src, ip_t, ipid_t);
      StringAccum sa_t;
      sa_t << "Encoded " << ip_t << " " << ipid_t;
      click_chatter("%s %s", id().cc(), sa_t.c_str());     
    }
    StringAccum sa;
    sa << et;
    click_chatter("%s got an encoded packet %s", id().cc(), sa.c_str());
    fwd_packet(p);
    return;
  }

  const click_ip *iph = p->ip_header();
  IPAddress ipsrc = IPAddress(iph->ip_src);
  uint16_t ipid = ntohs(iph->ip_id);

  if (src != _myea) {
    _guessmgr->register_guess(src, ipsrc, ipid);
  }

  if (dst == _myea) {
    click_chatter("%s packet addressed to me. just forward it", id().cc());
    fwd_packet(p);
    return;
  }

  bool isnew = _listenmgr->register_packet_to_recp(p, now);

  if (isnew) {
    _scrambleq->wakeup_if_needed();
  }

  fwd_packet(p);
}

 
CLICK_ENDDECLS
EXPORT_ELEMENT(OverheardPackets)