udpipencaps.cc

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

/*
 * udpipencap.{cc,hh} -- element encapsulates packet in UDP/IP header
 * Benjie Chen, Eddie Kohler
 *
 * Copyright (c) 1999-2000 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 <clicknet/ip.h>
#include "udpipencaps.hh"
#include <click/confparse.hh>
#include <click/error.hh>
#include <click/glue.hh>
#include <click/straccum.hh>
#include <click/string.hh>
#include <click/standard/alignmentinfo.hh>
#ifdef CLICK_LINUXMODULE
# include <net/checksum.h>
#endif
CLICK_DECLS

UDPIPEncaps::UDPIPEncaps()
  : Element(1, 1)
{
}

UDPIPEncaps::~UDPIPEncaps()
{
}

int
UDPIPEncaps::configure(Vector<String> &conf, ErrorHandler *errh)
{
  bool do_cksum = true;
  if (cp_va_parse(conf, this, errh,
		  cpOptional,
		  cpBool, "do UDP checksum?", &do_cksum,
		  cpEnd) < 0)
    return -1;

  _id = 0;
  _cksum = do_cksum;

#if HAVE_FAST_CHECKSUM && FAST_CHECKSUM_ALIGNED
  // check alignment
  {
    int ans, c, o;
    ans = AlignmentInfo::query(this, 0, c, o);
    _aligned = (ans && c == 4 && o == 0);
    if (!_aligned)
      errh->warning("IP header unaligned, cannot use fast IP checksum");
    if (!ans)
      errh->message("(Try passing the configuration through `click-align'.)");
  }
#endif
  
  _nflows = 0;
  _flowidx = -1;
  return 0;
}

Packet *
UDPIPEncaps::simple_action(Packet *p_in)
{
  WritablePacket *p = p_in->push(sizeof(click_udp) + sizeof(click_ip));
  click_ip *ip = reinterpret_cast<click_ip *>(p->data());
  click_udp *udp = reinterpret_cast<click_udp *>(ip + 1);

  // set up IP header
  ip->ip_v = 4;
  ip->ip_hl = sizeof(click_ip) >> 2;
  ip->ip_len = htons(p->length());
  ip->ip_id = htons(_id.read_and_add(1));
  ip->ip_p = IP_PROTO_UDP;
  ip->ip_src = _flows[_flowidx]->_src.in_addr();
  ip->ip_dst = _flows[_flowidx]->_dst.in_addr();
  ip->ip_tos = 0;
  ip->ip_off = 0;
  ip->ip_ttl = 250;

  ip->ip_sum = 0;
#if HAVE_FAST_CHECKSUM && FAST_CHECKSUM_ALIGNED
  if (_aligned)
    ip->ip_sum = ip_fast_csum((unsigned char *)ip, sizeof(click_ip) >> 2);
  else
    ip->ip_sum = click_in_cksum((unsigned char *)ip, sizeof(click_ip));
#elif HAVE_FAST_CHECKSUM
  ip->ip_sum = ip_fast_csum((unsigned char *)ip, sizeof(click_ip) >> 2);
#else
  ip->ip_sum = click_in_cksum((unsigned char *)ip, sizeof(click_ip));
#endif
  
  p->set_dst_ip_anno(_flows[_flowidx]->_dst);
  p->set_ip_header(ip, sizeof(click_ip));

  // set up UDP header
  udp->uh_sport = htons((short)_flows[_flowidx]->_sport);
  udp->uh_dport = htons((short)_flows[_flowidx]->_dport);
  uint16_t len = p->length() - sizeof(click_ip);
  udp->uh_ulen = htons(len);
  udp->uh_sum = 0;
  if (_cksum) {
    unsigned csum = click_in_cksum((unsigned char *)udp, len);
    udp->uh_sum = click_in_cksum_pseudohdr(csum, ip, len);
  }
  StringAccum sa;
  sa << "Src: " << IPAddress(ip->ip_src) << " Dst: " << IPAddress(ip->ip_dst) << " sp: " << ntohs(udp->uh_sport) << " dp: " << ntohs(udp->uh_dport);
  click_chatter("forwarding a packet %s", sa.c_str());
  if (_flowidx == (_nflows-1)) {
    _flowidx = 0;
  } else {
    _flowidx++;
  }
  return p;
}

int
UDPIPEncaps::add_flow(const String &arg, Element *e, void *, ErrorHandler *errh)
{
  Vector<String> args;
  UDPIPEncaps *me = static_cast<UDPIPEncaps *>(e); 

  cp_spacevec(arg, args);

  UDPFlow *newflow = new UDPFlow();

  me->_flows.push_back(newflow);
  if (!cp_ip_address(args[0], &me->_flows[me->_nflows]->_src)) {
       return errh->error("Couldn't read arg %d to src IP address: %s", 0, args[0].cc());
  }
 
  if (!cp_unsigned(args[1], &me->_flows[me->_nflows]->_sport)) {
       return errh->error("Couldn't read arg %d to src port: %s", 1, args[1].cc());
  }

  if (!cp_ip_address(args[2], &me->_flows[me->_nflows]->_dst)) {
       return errh->error("Couldn't read arg %d to dst IP address: %s", 2, args[2].cc());
  }
 
  if (!cp_unsigned(args[3], &me->_flows[me->_nflows]->_dport)) {
       return errh->error("Couldn't read arg %d to dst port: %s", 3, args[3].cc());
  }
  StringAccum sa;
  sa << "Src: " << me->_flows[me->_nflows]->_src << " sport: " << me->_flows[me->_nflows]->_sport << " Dst: " << me->_flows[me->_nflows]->_dst << " dport: " << me->_flows[me->_nflows]->_dport;
  click_chatter("%s",sa.c_str());
  me->_nflows++;
  if (me->_flowidx == -1) {
    me->_flowidx = 0;
  }
  return 1;
}

void
UDPIPEncaps::add_handlers()
{
  add_write_handler("flow", add_flow, (void*)0);
}

CLICK_ENDDECLS
EXPORT_ELEMENT(UDPIPEncaps)
ELEMENT_MT_SAFE(UDPIPEncaps)