mac-802_11.cc

ns2 中802.11 mac层的实现代码！

/* -*-	Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*-
 *
 * Copyright (c) 1997 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the Computer Systems
 *	Engineering Group at Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $Header: /u23/ns-user/cvsroot/ns-2/mac-802_11.cc,v 1.1.1.1.6.3 2001/08/20 12:04:14 dugdale Exp $
 *
 * Ported from CMU/Monarch's code, nov'98 -Padma.
 */
/*
 * Code contained within lines such as the below
 *
  // wqos - <date> - dugdale
  // wqos - changes by dugdale ends
 *
 * or
 *
  // wqos - <date> - almquist
  // wqos - changes by almquist ends
 *
 * have been changed or added to implement the PCF mode of IEEE 802.11 and is
 * Copyright (c) 2001 Anders Lindgren and Andreas Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the above disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the above disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 *    The disclaimer above apply to the modifications made to the source code
 *    by Anders Lindgren and Andreas Almquist as well as to the rest of the code.
 */

#include "delay.h"
#include "connector.h"
#include "packet.h"
#include "random.h"
#include "mobilenode.h"

// #define DEBUG

#include "arp.h"
#include "ll.h"
#include "mac.h"
#include "mac-timers.h"
#include "mac-802_11.h"
#include "cmu-trace.h"


// XXX Can't we make these macros inline methods? Otherwise why should we have
// inline methods at all??

#define CHECK_BACKOFF_TIMER()						\
{									\
	if(is_idle() && mhBackoff_.paused())				\
		mhBackoff_.resume(difs_);				\
	if(! is_idle() && mhBackoff_.busy() && ! mhBackoff_.paused())	\
		mhBackoff_.pause();					\
}

#define TRANSMIT(p, t)                                                  \
{                                                                       \
	tx_active_ = 1;                                                  \
                                                                        \
        /*                                                              \
         * If I'm transmitting without doing CS, such as when           \
         * sending an ACK, any incoming packet will be "missed"         \
         * and hence, must be discarded.                                \
         */                                                             \
        if(rx_state_ != MAC_IDLE) {                                      \
                struct hdr_mac802_11 *dh = HDR_MAC802_11(p);                  \
                                                                        \
                assert(dh->dh_fc.fc_type == MAC_Type_Control);          \
                assert(dh->dh_fc.fc_subtype == MAC_Subtype_ACK);        \
                                                                        \
                assert(pktRx_);                                          \
                struct hdr_cmn *ch = HDR_CMN(pktRx_);                    \
                                                                        \
                ch->error() = 1;        /* force packet discard */      \
        }                                                               \
                                                                        \
        /*                                                              \
         * pass the packet on the "interface" which will in turn        \
         * place the packet on the channel.                             \
         *                                                              \
         * NOTE: a handler is passed along so that the Network          \
         *       Interface can distinguish between incoming and         \
         *       outgoing packets.                                      \
         */                                                             \
        downtarget_->recv(p->copy(), this);                             \
                                                                        \
        mhSend_.start(t);                                                \
                                                                        \
	mhIF_.start(TX_Time(p));                                         \
}

#define SET_RX_STATE(x)			\
{					\
	rx_state_ = (x);		\
	CHECK_BACKOFF_TIMER();		\
}

#define SET_TX_STATE(x)				\
{						\
	tx_state_ = (x);			\
	CHECK_BACKOFF_TIMER();			\
}

/* ======================================================================
   Global Variables
   ====================================================================== */

static PHY_MIB PMIB =
{
	DSSS_CWMin, DSSS_CWMax, DSSS_SlotTime, DSSS_CCATime,
	DSSS_RxTxTurnaroundTime, DSSS_SIFSTime, DSSS_PreambleLength,
	DSSS_PLCPHeaderLength
};	

static MAC_MIB MMIB =
{
	0 /* MAC_RTSThreshold */, MAC_ShortRetryLimit,
	MAC_LongRetryLimit, MAC_FragmentationThreshold,
	MAC_MaxTransmitMSDULifetime, MAC_MaxReceiveLifetime,
  // wqos - Wed 04 Oct 00, 11:10 - dugdale
  0 /* CF Pollable */, 1 /* CFP Period */, 15 /* CFP Max Duration*/,
  20 /* BeaconPeriod */, 0 /* DTIM Period */,
  // wqos - changes by dugdale ends
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/* ======================================================================
   TCL Hooks for the simulator
   ====================================================================== */
static class Mac802_11Class : public TclClass {
public:
	Mac802_11Class() : TclClass("Mac/802_11") {}
	TclObject* create(int, const char*const*) {
		return (new Mac802_11(&PMIB, &MMIB));
	}
} class_mac802_11;


/* ======================================================================
   Mac Class Functions
   ====================================================================== */
Mac802_11::Mac802_11(PHY_MIB *p, MAC_MIB *m) : Mac(),
	mhIF_(this), mhNav_(this), mhRecv_(this), mhSend_(this),
	mhDefer_(this, p->SlotTime), mhBackoff_(this, p->SlotTime),
// wqos - Sat 18 Aug 01, 16:49 - dugdale 
       mhBeacon_(this)				       
// wqos - changes by dugdale ends
{
	macmib_ = m;
	phymib_ = p;

	nav_ = 0.0;

	tx_state_ = rx_state_ = MAC_IDLE;
	tx_active_ = 0;

	pktRTS_ = 0;
	pktCTRL_ = 0;

	cw_ = phymib_->CWMin;
	ssrc_ = slrc_ = 0;

	sifs_ = phymib_->SIFSTime;
	pifs_ = sifs_ + phymib_->SlotTime;
	difs_ = sifs_ + 2*phymib_->SlotTime;
	eifs_ = sifs_ + difs_ + DATA_Time(ETHER_ACK_LEN +
		phymib_->PreambleLength/8 + phymib_->PLCPHeaderLength/8);
	tx_sifs_ = sifs_ - phymib_->RxTxTurnaroundTime;
	tx_pifs_ = tx_sifs_ + phymib_->SlotTime;
	tx_difs_ = tx_sifs_ + 2 * phymib_->SlotTime;

	sta_seqno_ = 1;
	cache_ = 0;
	cache_node_count_ = 0;

  // wqos - Fri 06 Oct 00, 10:29 - dugdale
  pc_=0; dtimcount_=0; cfp_=0; 
  cfpcount_ = macmib_->dot11CFPPeriod;
  pktPCF_ = 0; pollList_=0;
  pollsToSend_=0; btbs_=0;
  // wqos - changes by dugdale ends
}
	

int
Mac802_11::command(int argc, const char*const* argv)
{
	if (argc >= 3) {
		if (strcmp(argv[1], "log-target") == 0) {
			logtarget_ = (NsObject*) TclObject::lookup(argv[2]);
			if(logtarget_ == 0)
				return TCL_ERROR;
			return TCL_OK;
		} else if(strcmp(argv[1], "nodes") == 0) {
			if(cache_) return TCL_ERROR;
			cache_node_count_ = atoi(argv[2]);
			cache_ = new Host[cache_node_count_ + 1];
			assert(cache_);
			bzero(cache_, sizeof(Host) * (cache_node_count_+1 ));
			return TCL_OK;
		}
// wqos - Sat 18 Aug 01, 12:39 - dugdale
		// If this node is a base station, add a station to its polling list
		else if(strcmp(argv[1], "addSTA") == 0){
			if(pc_) {
				int macId = atoi(argv[2]);
				int cfPollable = atoi(argv[3]);
				int cfPollReq = atoi(argv[4]);
				
				pollList_->insertNode(macId, cfPollable, cfPollReq);
				// TODO: Some debug printouts and errorchecking.
				//      free(tmpstr);
				return TCL_OK;
			} else
				return TCL_ERROR;
		}
		// If this node is a base station, remove a station from its polling list
		else if(strcmp(argv[1], "remSTA") == 0){
			if(pc_) {
				int macId = atoi(argv[2]);
				if(pollList_->deleteNode(macId)==0)
					return TCL_OK;
				else
					return TCL_ERROR;
			} else
				return TCL_ERROR;
		}
		// Sets the beacon period
		else if(strcmp(argv[1], "beaconperiod") == 0){
			macmib_->dot11BeaconPeriod = atoi(argv[2]);
			// Calculate the maximum length of a CFP (the CFP interval - the time
			// to send a maximum length frame)
			// (Each beacon starts a CFP)
			macmib_->dot11CFPMaxDuration = macmib_->dot11CFPPeriod*(macmib_->dot11DTIMPeriod+1)*macmib_->dot11BeaconPeriod - tu(2346/bandwidth_);
			return TCL_OK;
		}
	} else if(argc==2) {
		// Let this node be the Point Coordinator
		if(strcmp(argv[1], "make-pc") == 0) {
			pc_=1;
			if(!pollList_)
				pollList_ = new PCFPollList();
			mhBeacon_.start(macmib_->dot11BeaconPeriod*0.001024);
			return TCL_OK;
		}
	}
	// wqos - changes by dugdale ends
	return Mac::command(argc, argv);
}

/* ======================================================================
   Debugging Routines
   ====================================================================== */
void
Mac802_11::trace_pkt(Packet *p) {
	struct hdr_cmn *ch = HDR_CMN(p);
	struct hdr_mac802_11* dh = HDR_MAC802_11(p);
	u_int16_t *t = (u_int16_t*) &dh->dh_fc;

	fprintf(stderr, "\t[ %2x %2x %2x %2x ] %x %s %d\n",
		*t, dh->dh_duration,
		ETHER_ADDR(dh->dh_da), ETHER_ADDR(dh->dh_sa),
		index_, packet_info.name(ch->ptype()), ch->size());
}

void
Mac802_11::dump(char *fname)
{
	fprintf(stderr,
		"\n%s --- (INDEX: %d, time: %2.9f)\n",
		fname, index_, Scheduler::instance().clock());

	fprintf(stderr,
		"\ttx_state_: %x, rx_state_: %x, nav: %2.9f, idle: %d\n",
		tx_state_, rx_state_, nav_, is_idle());

	fprintf(stderr,
		"\tpktTx_: %x, pktRx_: %x, pktRTS_: %x, pktCTRL_: %x, callback: %x\n",
		(int) pktTx_, (int) pktRx_, (int) pktRTS_,
		(int) pktCTRL_, (int) callback_);

	fprintf(stderr,
		"\tDefer: %d, Backoff: %d (%d), Recv: %d, Timer: %d Nav: %d\n",
		mhDefer_.busy(), mhBackoff_.busy(), mhBackoff_.paused(),
		mhRecv_.busy(), mhSend_.busy(), mhNav_.busy());
	fprintf(stderr,
		"\tBackoff Expire: %f\n",
		mhBackoff_.expire());
}


/* ======================================================================
   Packet Headers Routines
   ====================================================================== */
inline int
Mac802_11::hdr_dst(char* hdr, int dst )
{
	struct hdr_mac802_11 *dh = (struct hdr_mac802_11*) hdr;
	//dst = (u_int32_t)(dst);

	if(dst > -2)
		STORE4BYTE(&dst, (dh->dh_da));

	return ETHER_ADDR(dh->dh_da);
}

inline int 
Mac802_11::hdr_src(char* hdr, int src )
{
	struct hdr_mac802_11 *dh = (struct hdr_mac802_11*) hdr;
	if(src > -2)
		STORE4BYTE(&src, (dh->dh_sa));
	return ETHER_ADDR(dh->dh_sa);
}

inline int 
Mac802_11::hdr_type(char* hdr, u_int16_t type)
{
	struct hdr_mac802_11 *dh = (struct hdr_mac802_11*) hdr;
	if(type)
		STORE2BYTE(&type,(dh->dh_body));
	return GET2BYTE(dh->dh_body);
}


/* ======================================================================
   Misc Routines
   ====================================================================== */
inline int
Mac802_11::is_idle()
{
	if(rx_state_ != MAC_IDLE)
		return 0;
	if(tx_state_ != MAC_IDLE)
		return 0;
	if(nav_ > Scheduler::instance().clock())
		return 0;
	return 1;
}

void
Mac802_11::discard(Packet *p, const char* why)
{
	hdr_mac802_11* mh = HDR_MAC802_11(p);
	hdr_cmn *ch = HDR_CMN(p);

#if 0
	/* old logic 8/8/98 -dam */
	/*
	 * If received below the RXThreshold, then just free.
	 */
	if(p->txinfo_.Pr < p->txinfo_.ant.RXThresh) {
		Packet::free(p);
		//p = 0;
		return;
	}
#endif // 0

	/* if the rcvd pkt contains errors, a real MAC layer couldn't
	   necessarily read any data from it, so we just toss it now */
	if(ch->error() != 0) {
		Packet::free(p);
		//p = 0;
		return;
	}

	switch(mh->dh_fc.fc_type) {
	case MAC_Type_Management:
		drop(p, why);
		return;
	case MAC_Type_Control:
		switch(mh->dh_fc.fc_subtype) {
		case MAC_Subtype_RTS:
			if((u_int32_t)ETHER_ADDR(mh->dh_sa) == \
			   (u_int32_t)index_) {
				drop(p, why);
				return;
			}
			/* fall through - if necessary */
		case MAC_Subtype_CTS:
		case MAC_Subtype_ACK:
			if((u_int32_t)ETHER_ADDR(mh->dh_da) == \
			   (u_int32_t)index_) {
				drop(p, why);
				return;
			}
			break;
// wqos - Sat 18 Aug 01, 17:17 - dugdale 			
		case MAC_Subtype_CFEnd:
		case MAC_Subtype_CFEnd_CFACK:
			break;			
// wqos - changes by dugdale ends
		default:
			fprintf(stderr, "invalid MAC Control subtype\n");
			exit(1);
		}
		break;
	case MAC_Type_Data:
		switch(mh->dh_fc.fc_subtype) {
		case MAC_Subtype_Data:
			if((u_int32_t)ETHER_ADDR(mh->dh_da) == \
			   (u_int32_t)index_ ||
			   (u_int32_t)ETHER_ADDR(mh->dh_sa) == \
			   (u_int32_t)index_ ||
			   (u_int32_t)ETHER_ADDR(mh->dh_da) == MAC_BROADCAST) {
				drop(p);
				return;
			}
			break;
// wqos - Sat 18 Aug 01, 17:17 - dugdale 			
		case MAC_Subtype_Data_CFACK:
		case MAC_Subtype_Data_CFACK_CFPoll:
		case MAC_Subtype_NullFunction:
		case MAC_Subtype_CFACK:
		case MAC_Subtype_CFPoll:
		case MAC_Subtype_CFACK_CFPoll:			
			break;
// wqos - changes by dugdale ends
		default:
			fprintf(stderr, "invalid MAC Data subtype\n");
			exit(1);
		}
		break;
	default:
		fprintf(stderr, "invalid MAC type (%x)\n", mh->dh_fc.fc_type);
		trace_pkt(p);
		exit(1);
	}
	Packet::free(p);
}

void
Mac802_11::capture(Packet *p)
{
	/*
	 * Update the NAV so that this does not screw
	 * up carrier sense.
	 */
	set_nav(usec(eifs_ + TX_Time(p)));
	Packet::free(p);
}

void
Mac802_11::collision(Packet *p)
{
	switch(rx_state_) {
	case MAC_RECV:
		SET_RX_STATE(MAC_COLL);
		/* fall through */
	case MAC_COLL:
		assert(pktRx_);
		assert(mhRecv_.busy());
		/*
		 *  Since a collision has occurred, figure out
		 *  which packet that caused the collision will
		 *  "last" the longest.  Make this packet,
		 *  pktRx_ and reset the Recv Timer if necessary.
		 */
		if(TX_Time(p) > mhRecv_.expire()) {
			mhRecv_.stop();
			discard(pktRx_, DROP_MAC_COLLISION);
			pktRx_ = p;
			mhRecv_.start(TX_Time(pktRx_));
		}
		else {
			discard(p, DROP_MAC_COLLISION);
		}
		break;
	default:
		assert(0);
	}
}

void
Mac802_11::tx_resume()
{
	assert(mhSend_.busy() == 0);
	assert(mhDefer_.busy() == 0);

	// wqos - Thu 09 Nov 00, 09:55 - dugdale
	if(btbs_) { // Make sure beacons are sent...
		btbs_=0;
		send_beacon();
	}
	// wqos - changes by dugdale ends

	if(pktCTRL_) {
		/*
		 *  Need to send a CTS or ACK.
		 */
		mhDefer_.start(sifs_);
	}
	// wqos - Tue 10 Oct 00, 14:17 - dugdale 
	else if(pktPCF_) { // We have been polled, and should send a packet
		//		if(mhBackoff_.busy() && !mhBackoff_.paused()) // Should we really do this?? 
		if(mhBackoff_.busy()) // Should we really do this?? 
			mhBackoff_.stop(); // Pausing
		//			mhBackoff_.pause(); // Pausing
		mhDefer_.start(sifs_);
		// We should only wait a SIFS to send this...
	}
	// wqos - changes by dugdale ends
	else if(pktRTS_) {
		if(mhBackoff_.busy() == 0)
			mhDefer_.start(difs_);
	} else if(pktTx_) {
		if(mhBackoff_.busy() == 0)
			mhDefer_.start(difs_);
	} else if(callback_) {
		Handler *h = callback_;
		callback_ = 0;
		h->handle((Event*) 0);
	}
	SET_TX_STATE(MAC_IDLE);
}