mac-802_11.cc

ns2 中802.11 mac层的实现代码！

			else {
				discard(p, DROP_MAC_BUSY);
				//printf("(%d)..discard DATA\n",index_);
				return;
			}
			sendACK(src);
			tx_resume();
		}
		/*
		 *  We did not send a CTS and there's no
		 *  room to buffer an ACK.
		 */
		else {
			if(pktCTRL_) {
				discard(p, DROP_MAC_BUSY);
				return;
			}
			sendACK(src);
			if(mhSend_.busy() == 0)
				tx_resume();
		}
	}

	/* ============================================================
	    Make/update an entry in our sequence number cache.
	   ============================================================ */

	/* Changed by Debojyoti Dutta. This upper loop of if{}else was 
	   suggested by Joerg Diederich <[e-mail]>. 
	   Changed on 19th Oct'2000 */

        if(dst != MAC_BROADCAST) {
                if (src < (u_int32_t) cache_node_count_) {
                        Host *h = &cache_[src];

                        if(h->seqno && h->seqno == dh->dh_scontrol) {
                                discard(p, DROP_MAC_DUPLICATE);
                                return;
                        }
                        h->seqno = dh->dh_scontrol;
                } else {
			static int count = 0;
			if (++count <= 10) {
				printf ("MAC_802_11: accessing MAC cache_ array out of range (src %u, dst %u, size %d)!\n", src, dst, cache_node_count_);
				if (count == 10)
					printf ("[suppressing additional MAC cache_ warnings]\n");
			};
		};
	}

	/*
	 *  Pass the packet up to the link-layer.
	 *  XXX - we could schedule an event to account
	 *  for this processing delay.
	 */
	p->incoming = 1;
	uptarget_->recv(p, (Handler*) 0);
}


void
Mac802_11::recvACK(Packet *p)
{
	
	struct hdr_cmn *ch = HDR_CMN(p);

	if(tx_state_ != MAC_SEND) {
	discard(p, DROP_MAC_INVALID_STATE);
	return;
	}
	//printf("(%d)...................recving ACK:%x\n",index_,p);
	assert(pktTx_);
	Packet::free(pktTx_); pktTx_ = 0;

	mhSend_.stop();

	/*
	 * The successful reception of this ACK packet implies
	 * that our DATA transmission was successful.  Hence,
	 * we can reset the Short/Long Retry Count and the CW.
	 */
	if((u_int32_t) ch->size() <= macmib_->RTSThreshold)
		ssrc_ = 0;
	else
		slrc_ = 0;

	/*
	 * Backoff before sending again.
	 */
	rst_cw();
	assert(mhBackoff_.busy() == 0);
	mhBackoff_.start(cw_, is_idle());

	tx_resume();

	mac_log(p);
}


// wqos - Wed 29 Nov 00, 13:20 - dugdale
void
Mac802_11::recvPoll(Packet *p) {
	Packet *tp;
	//      tp = ll_->ifq()->deque();
	//      tp = ((Queue *)((LL *)uptarget_)->downtarget())->deque();
	mac_log(p);
	//  rx_resume();
	// Hmmm... maybe not so good...
	//	if(mhBackoff_.busy() && !mhBackoff_.paused())
	if(mhBackoff_.busy())
		mhBackoff_.stop();
	//		mhBackoff_.pause();
 retryPoll:
	if(!pktTx_) {
  		// Unless there already is a packet to be sent, try to dequeuec one
		tp = ((Queue *)(ll_->downtarget()))->deque();
		if(tp) { // Did we get a packet from the queue?
			//	abort();
			//send(tp, 0);
			//if(!pollsToSend_)
			//pollsToSend_=1;
			trace_pkt(tp);



			// Try with this commented out!!!
			// It is NOT good that the stuff below is here, but for some strange
			// reason it won't work without it... Not really correct, but it
			// works until I find out what's wrong.
			if(HDR_CMN(tp)->ptype()==PT_ARP||HDR_CMN(tp)->ptype()==PT_MESSAGE) {
				Packet::free(tp); tp=0;
				goto retryPoll;
			}
			sendDATA(tp);
			
			fprintf(stderr, "Hej %x %x %d %d!\n", ((struct hdr_mac802_11 *)pktTx_)->dh_fc.fc_type,((struct hdr_mac802_11 *)pktTx_)->dh_fc.fc_subtype,((struct hdr_mac802_11 *)HDR_MAC802_11(pktTx_))->dh_scontrol, pktTx_==0);
			
			
			((struct hdr_mac802_11 *)HDR_MAC802_11(pktTx_))->dh_scontrol = sta_seqno_++;
			((struct hdr_mac802_11 *)HDR_MAC802_11(pktTx_))->dh_duration = 32768;
		}
	} else {
		trace_pkt(pktTx_);


		if(HDR_CMN(pktTx_)->ptype()==PT_ARP||HDR_CMN(pktTx_)->ptype()==PT_MESSAGE) {
			Packet::free(pktTx_); pktTx_=0;
			goto retryPoll;
		}
		
		//if(!pollsToSend_)
		//pollsToSend_=1;
		fprintf(stderr,"tx_state_:%x %d\n",tx_state_,cfp_);
		((struct hdr_mac802_11 *)HDR_MAC802_11(pktTx_))->dh_duration = 32768;
		
		if(pktRTS_) {
			// We won't be needing this RTS frame
			Packet::free(pktRTS_); pktRTS_=0; 
		}
		
	}
	if(!mhDefer_.busy()&&pktTx_)
		mhDefer_.start(sifs_);
	

	// If there is no packet to send in the queue, the station won't do anything, so a
	// timer will time out at the PC, and a new poll frame will be sent (to another station)
	// Would be better if this station sent a "No data" frame in this case.
	// Not implemented yet.

}
// wqos - changes by dugdale ends


// wqos - Mon 09 Oct 00, 20:01 - dugdale 
void
Mac802_11::do_cfp()
{
	// Hmmm... Not much use having this function
	sendPoll();
}

void
Mac802_11::send_beacon()
{
	if(tx_state_!=MAC_SEND&&tx_state_!=MAC_CTS && rx_state_==MAC_IDLE) {
		// We can send the beacon now
		pcfSend(MAC_Type_Management, MAC_Subtype_Beacon);
	} else {
		// We have to wait to send the beacon, but set the flag
		// (btbs=beacon to be sent) so we know that it should be sent.
		btbs_=1;
	}
}

void
Mac802_11::sendPoll()
{
	pcfSend(MAC_Type_Data, MAC_Subtype_CFPoll);
}

void
Mac802_11::sendCFEnd()
{
	pcfSend(MAC_Type_Control, MAC_Subtype_CFEnd);
}
// wqos - changes by dugdale ends


// wqos - Tue 24 Oct 00, 10:20 - dugdale
/*
	Function to send the control frames of the PCF mode.
	The frame sent depends on the arguments to the function.
	Called by send_beacon(), sendPoll(), and sendCFEnd().
 */
void
Mac802_11::pcfSend(int type, int subtype)
{
	Packet* p = Packet::alloc();
	struct hdr_mac802_11 *mh =  (struct hdr_mac802_11 *)p->access(hdr_mac::offset_);
	hdr_cmn* ch = HDR_CMN(p);
	ch->ptype()=PT_MAC;
	int dst = MAC_BROADCAST;
	double defertime=pifs_;
	Scheduler &s = Scheduler::instance();
    
	bzero(&mh->dh_fc, sizeof(struct frame_control));
	// Set some info in the frame
	mh->dh_fc.fc_protocol_version = MAC_ProtocolVersion;
	mh->dh_fc.fc_type       = type;
	mh->dh_fc.fc_subtype    = subtype;
	/*
	 * Assign the data packet a sequence number.
	 */
	mh->dh_scontrol = sta_seqno_++;
	ch->size() += ETHER_HDR_LEN;
  
	switch(type) {
	case MAC_Type_Management:
		switch(subtype) {
		case MAC_Subtype_Beacon:
			struct beacon_frame *beacon = (struct beacon_frame *)p->access(hdr_mac::offset_);
			// Schedule the transmission of the next beacon
			// Moved to beaconHandler()
			//			mhBeacon_.start(macmib_->dot11BeaconPeriod*0.001024);
      
			// do some timestamp stuff, and set it in the frame
			beacon->bf_timestamp=(unsigned long long)((Scheduler::instance()).clock()*1000);
      
			// Set the beacon interval in the frame
			beacon->bf_binterval=macmib_->dot11BeaconPeriod;
      
      
			//     assert(pktPCF_ == 0);

			fprintf(stderr, "Beacon sent at %f\n", Scheduler::instance().clock());
      
			// set the TIM stuff
			beacon->bf_tim.elemID       = MMFF_TIM;
			beacon->bf_tim.length       = 6;
			beacon->bf_tim.DTIMcount    = dtimcount_;
			beacon->bf_tim.DTIMperiod   = macmib_->dot11DTIMPeriod;
      
			beacon->bf_cfparamset.CFPCount  = cfpcount_;
			beacon->bf_cfparamset.CFPPeriod = macmib_->dot11CFPPeriod;
			beacon->bf_cfparamset.CFPMaxDuration = macmib_->dot11CFPMaxDuration;
      
			beacon->bf_duration = 0;
			if(dtimcount_==0) {
				// We have a DTIM, and might want to start a CFP
				dtimcount_=macmib_->dot11DTIMPeriod;
				cfpcount_--;
				beacon->bf_cfparamset.CFPCount  = cfpcount_;
				if(cfpcount_ == 0) { // Let's do a CFP
					//					cfp_ = 1; // CFP...
					cfpcount_ = macmib_->dot11CFPPeriod;
					// Calculate how many polls to send
					pollsToSend_=pollList_->numPollable()-1;
					// Calculate when the CFP must be over
					lastPoll_=s.clock()+tutos(macmib_->dot11CFPMaxDuration) - 2346/bandwidth_;
				}
			} else {
				dtimcount_--;
			}
			//     SET_TX_STATE(MAC_BEACONING); // HMMM...      
			break;
		}
		break;
	case MAC_Type_Control:
		switch(subtype) {
		case MAC_Subtype_CFEnd:
			fprintf(stderr,"CFEnd: %f\n",s.clock());
			//      assert(pktPCF_ == 0);
      
      
			mh->dh_duration = 32768;
			//			mh->dh_scontrol = sta_seqno_++;
      
			cfp_ = 0;
      
			break;
		}
		break;
	case MAC_Type_Data:
		switch(subtype) {
		case MAC_Subtype_CFPoll:
			dst=pollList_->getNextPollable();
			defertime=sifs_;
			if(dst==-1) { // No stations to poll...
				sendCFEnd(); 
				return;
			}
			fprintf(stderr,"Poll: %d %f\n",dst,s.clock());
			//     assert(pktPCF_ == 0);
      
			mh->dh_duration = 32768; // This is sent during a CFP
      
			mh->dh_scontrol = sta_seqno_++;

			break;
		}
		break;
	}

	pktPCF_ = p;

	STORE4BYTE(&dst,(mh->dh_da));
	STORE4BYTE(&index_, (mh->dh_sa));

	/* CAN THIS BE REMOVED?????? /dugdale
	 * drop the packet if the node is in sleep mode
	 XXX sleep mode can't stop node from sending packets
	*/
	EnergyModel *em = netif_->node()->energy_model();
	if (em && em->sleep()) {
		em->set_node_sleep(0);
		em->set_node_state(EnergyModel::INROUTE);
	}

	if(mhBackoff_.busy() == 0) {
		if(is_idle()) {
			/*
			 * If we are already deferring, there is no
			 * need to reset the Defer timer.
			 */
			if(mhDefer_.busy() == 0)
				mhDefer_.start(defertime);
		}
		
		/*
		 * If the medium is NOT IDLE, then we start
		 * the backoff timer.
		 */

		// Should we really do this here????????? /dugdale
		else {
			mhBackoff_.start(cw_, is_idle());
		}
	}
}
// wqos - changes by dugdale ends



// wqos - Fri 06 Oct 00, 11:20 - almquist
/* ======================================================================
   Implementation of the PCFPollList 
   ======================================================================

	 This polling list is used by the Point Coordinator (PC) in the PCF scheme
	 to maintain a list of stations to poll (and of those not to poll as well).	 
*/

/**
	 Constructor

	 This will initialize the list and set nextToBePolled to the first element in the list.
 */
PCFPollList::PCFPollList(){
	lastPollable = lastPolled = firstElement = lastElement = NULL;
  // nrOfNodes = 0;
  fprintf(stderr, "DEBUG: PCFPollList created\n");
}

/**
	 Destructor

	 This removes all elements in the poll list.
*/
PCFPollList::~PCFPollList(){
  PCFPollElement *elem = firstElement;
	PCFPollElement *tmpElem;
	firstElement = lastElement = NULL;
  fprintf(stderr, "DEBUG: PCFPollList: Deleting elements with macId_ : ");
  while(elem != NULL){		
		tmpElem = elem;
		elem = elem->next_;
		fprintf(stderr, "%d, ", elem->macId_);
    delete tmpElem;		
	}
  fprintf(stderr, "\nDEBUG: PCFPollList destroyed\n");
}

/**
	 This will return the macId of the node to be polled.
	 
	 @return The macId of the node to be polled or -1 if no nodes in list
 */
int
PCFPollList::getNextPollable(){
  PCFPollElement *toBePolled;
  if(firstElement == NULL){
    return -1;
  }

  if(lastPolled == NULL || lastPolled == lastElement){
    toBePolled = firstElement;
  } else {
    toBePolled = lastPolled->next_;
  }
	
  switch(toBePolled->cfPollField_){
  case 0: // STA is not pollable
  case 1: // STA pollable but not req. to be put on pollinglist
	case 3: // STA pollable but req. never to be polled (PowerSave)
		if(toBePolled == lastElement){
			return -1;
		} else {
			return(this->getNextPollable());
		}
    break;
	case 2: // STA pollable and in pollinglist
    if(toBePolled->dontPoll_){
      return(this->getNextPollable());
    }
    lastPollable = toBePolled;
    break;
  default:
    fprintf(stderr, "Error: PCFPollList getNextPollable(): node %d has invalid CFPollable+CFPollReq fields, %x !\n", toBePolled->macId_, toBePolled->cfPollField_);
    break;
  }
  lastPolled = toBePolled;
  return toBePolled->macId_;
}

/**
	 This inserts an element last in the poll list.

	 @param macId        The mac id of the node to insert.
	 @param cfPollable   Indicates if this node is pollable (1 or 0)
	 @param cfPollReq    Indicates if this node should be polled (1 or 0)
 */
void
PCFPollList::insertNode(int macId, int cfPollable, int cfPollReq){
  int cfPollField = (cfPollable<<1) | cfPollReq;
  fprintf(stderr, "DEBUG: PCFPollList insertNode(%d, %d, %d): cfPollField = %d\n",
	  macId, cfPollable, cfPollReq, cfPollField);
  PCFPollElement *elem = new PCFPollElement(macId, cfPollField);
  if(firstElement == NULL){
    firstElement = lastElement = elem;
  } else {
    lastElement->next_ = elem;
    lastElement = elem;
  }
  // nrOfNodes++;
}

/**
   Deletes a node from the list
   Returns zero if successful, otherwise -1
*/
int
PCFPollList::deleteNode(int macId) {
  PCFPollElement *prev=NULL, *elem = firstElement;
  while(elem != NULL){
    if(elem->macId_==macId) { // Remove this node from the list
      if(prev)
	prev->next_ = elem->next_;
      else
	firstElement = elem->next_;
      if(!elem->next_) {
	lastElement = prev;
	prev->next_=NULL;
      }
      if(elem==lastPolled)
	lastPolled=NULL;
      delete(elem);
      return 0;
    }
    prev=elem;
    elem = elem->next_;
  }
  return -1;
}

/**
   Initializes the list.
*/
void
PCFPollList::initPoll(){
  lastPolled = NULL;
  clearDontPoll();
}

/**
   Used to perform some sort of polling policy.
   
   @param macId if this is -1 disable last polled STA
*/
void
PCFPollList::markDontPoll(int macId){
  if(macId != -1){
    PCFPollElement *elem = firstElement;
    while(elem != NULL && elem->macId_ != macId){
      elem = elem->next_;
    }
    elem->dontPoll_ = 1;
  } else {
    lastPolled->dontPoll_ = 1;
  }
}

/**
	 Clears the dontPoll_ flag in all pollable nodes.
 */
void
PCFPollList::clearDontPoll(){
  PCFPollElement *elem = firstElement;
  while(elem != NULL){
    elem->dontPoll_ = 0;
    elem = elem->next_;
  }
}

/**
       Returns the number of pollable stations
 */
int
PCFPollList::numPollable() {
  PCFPollElement *elem = firstElement;
  int num=0;
  while(elem) {
    if(elem->cfPollField_ == 2)
      num++;
    elem = elem->next_;
  }
  return num;
}

// wqos - changes by almquist ends