radiotapdecap.cc

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

/*
 * radiotapdecap.{cc,hh} -- decapsultates 802.11 packets
 * John Bicket
 *
 * Copyright (c) 2004 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 "radiotapdecap.hh"
#include <click/etheraddress.hh>
#include <click/confparse.hh>
#include <click/error.hh>
#include <click/glue.hh>
#include <clicknet/wifi.h>
#include <clicknet/radiotap.h>
#include <click/packet_anno.hh>
#include <clicknet/llc.h>
CLICK_DECLS

#define NUM_RADIOTAP_ELEMENTS 18

static const int radiotap_elem_to_bytes[NUM_RADIOTAP_ELEMENTS] = 
	{8, /* IEEE80211_RADIOTAP_TSFT */
	 1, /* IEEE80211_RADIOTAP_FLAGS */
	 1, /* IEEE80211_RADIOTAP_RATE */
	 4, /* IEEE80211_RADIOTAP_CHANNEL */
	 2, /* IEEE80211_RADIOTAP_FHSS */
	 1, /* IEEE80211_RADIOTAP_DBM_ANTSIGNAL */
	 1, /* IEEE80211_RADIOTAP_DBM_ANTNOISE */
	 2, /* IEEE80211_RADIOTAP_LOCK_QUALITY */
	 2, /* IEEE80211_RADIOTAP_TX_ATTENUATION */
	 2, /* IEEE80211_RADIOTAP_DB_TX_ATTENUATION */
	 1, /* IEEE80211_RADIOTAP_DBM_TX_POWER */
	 1, /* IEEE80211_RADIOTAP_ANTENNA */
	 1, /* IEEE80211_RADIOTAP_DB_ANTSIGNAL */
	 1, /* IEEE80211_RADIOTAP_DB_ANTNOISE */
	 2, /* IEEE80211_RADIOTAP_RX_FLAGS */
	 2, /* IEEE80211_RADIOTAP_TX_FLAGS */
	 1, /* IEEE80211_RADIOTAP_RTS_RETRIES */
	 1, /* IEEE80211_RADIOTAP_DATA_RETRIES */
	};

static int rt_el_present(struct ieee80211_radiotap_header *th, u_int32_t element)
{
	if (element > NUM_RADIOTAP_ELEMENTS)
		return 0;
	return th->it_present & (1 << element);
}

static int rt_check_header(struct ieee80211_radiotap_header *th, int len) 
{
	int bytes = 0;
	int x = 0;
	if (th->it_version != 0) 
		return 0;

	if (th->it_len < sizeof(struct ieee80211_radiotap_header))
		return 0;
	
	for (x = 0; x < NUM_RADIOTAP_ELEMENTS; x++) {
		if (rt_el_present(th, x))
		    bytes += radiotap_elem_to_bytes[x];
	}

	if (th->it_len < sizeof(struct ieee80211_radiotap_header) + bytes) 
		return 0;
	
	if (th->it_len > len)
		return 0;

	return 1;
}

static u_int8_t *rt_el_offset(struct ieee80211_radiotap_header *th, u_int32_t element) {
	unsigned int x = 0;
	u_int8_t *offset = ((u_int8_t *) th) + sizeof(ieee80211_radiotap_header);
	for (x = 0; x < NUM_RADIOTAP_ELEMENTS && x < element; x++) {
		if (rt_el_present(th, x))
			offset += radiotap_elem_to_bytes[x];
	}

	return offset;
}

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

RadiotapDecap::~RadiotapDecap()
{
}

int
RadiotapDecap::configure(Vector<String> &conf, ErrorHandler *errh)
{

  _debug = false;
  if (cp_va_parse(conf, this, errh,
		  /* not required */
		  cpKeywords,
		  "DEBUG", cpBool, "Debug", &_debug,
		  cpEnd) < 0)
    return -1;
  return 0;
}

Packet *
RadiotapDecap::simple_action(Packet *p)
{
	struct ieee80211_radiotap_header *th = (struct ieee80211_radiotap_header *) p->data();
	struct click_wifi_extra *ceh = (struct click_wifi_extra *) p->all_user_anno();
	if (rt_check_header(th, p->length())) {
		ceh->magic = WIFI_EXTRA_MAGIC;

		if (rt_el_present(th, IEEE80211_RADIOTAP_RATE)) {
			ceh->rate = *((u_int8_t *) rt_el_offset(th, IEEE80211_RADIOTAP_RATE));
		}

		if (rt_el_present(th, IEEE80211_RADIOTAP_DBM_ANTSIGNAL))
			ceh->rssi = *((u_int8_t *) rt_el_offset(th, IEEE80211_RADIOTAP_DBM_ANTSIGNAL));

		if (rt_el_present(th, IEEE80211_RADIOTAP_DBM_ANTNOISE))
			ceh->silence = *((u_int8_t *) rt_el_offset(th, IEEE80211_RADIOTAP_DBM_ANTNOISE));

		if (rt_el_present(th, IEEE80211_RADIOTAP_DB_ANTSIGNAL))
			ceh->rssi = *((u_int8_t *) rt_el_offset(th, IEEE80211_RADIOTAP_DB_ANTSIGNAL));

		if (rt_el_present(th, IEEE80211_RADIOTAP_DB_ANTNOISE))
			ceh->silence = *((u_int8_t *) rt_el_offset(th, IEEE80211_RADIOTAP_DB_ANTNOISE));

		if (rt_el_present(th, IEEE80211_RADIOTAP_RX_FLAGS)) {
			u_int16_t flags = *((u_int16_t *) rt_el_offset(th, IEEE80211_RADIOTAP_RX_FLAGS));
			if (flags & IEEE80211_RADIOTAP_F_RX_BADFCS) 
				ceh->flags |= WIFI_EXTRA_RX_ERR;
		}

		if (rt_el_present(th, IEEE80211_RADIOTAP_TX_FLAGS)) {
			u_int16_t flags = *((u_int16_t *) rt_el_offset(th, IEEE80211_RADIOTAP_TX_FLAGS));
			ceh->flags |= WIFI_EXTRA_TX;
			if (flags & IEEE80211_RADIOTAP_F_TX_FAIL) 
				ceh->flags |= WIFI_EXTRA_TX_FAIL;

			if (flags & IEEE80211_RADIOTAP_F_FCS) {
				p->take(4);
			}
		}

		if (rt_el_present(th, IEEE80211_RADIOTAP_DATA_RETRIES))
			ceh->retries = *((u_int8_t *) rt_el_offset(th, IEEE80211_RADIOTAP_DATA_RETRIES));
		
		p->pull(th->it_len);
	}

  return p;
}


enum {H_DEBUG};

static String 
RadiotapDecap_read_param(Element *e, void *thunk)
{
  RadiotapDecap *td = (RadiotapDecap *)e;
    switch ((uintptr_t) thunk) {
      case H_DEBUG:
	return String(td->_debug) + "\n";
    default:
      return String();
    }
}
static int 
RadiotapDecap_write_param(const String &in_s, Element *e, void *vparam,
		      ErrorHandler *errh)
{
  RadiotapDecap *f = (RadiotapDecap *)e;
  String s = cp_uncomment(in_s);
  switch((int)vparam) {
  case H_DEBUG: {    //debug
    bool debug;
    if (!cp_bool(s, &debug)) 
      return errh->error("debug parameter must be boolean");
    f->_debug = debug;
    break;
  }
  }
  return 0;
}
 
void
RadiotapDecap::add_handlers()
{
  add_default_handlers(true);

  add_read_handler("debug", RadiotapDecap_read_param, (void *) H_DEBUG);

  add_write_handler("debug", RadiotapDecap_write_param, (void *) H_DEBUG);
}
CLICK_ENDDECLS
EXPORT_ELEMENT(RadiotapDecap)