aodv.cc

对IEEE 802.11e里的分布式信道接入算法EDCA进行改进

/* 
   aodv.cc
   $Id: aodv.cc,v 1.7 2000/03/10 00:57:29 yaxu Exp $
 */

/* The AODV code developed by the CMU/MONARCH group was optimized
 * and tuned by Samir Das (UTSA) and Mahesh Marina (UTSA). The 
 * work was partially done in Sun Microsystems.
 * 
 * The original CMU copyright is below. 
 */

/*
Copyright (c) 1997, 1998 Carnegie Mellon University.  All Rights
Reserved. 

Permission to use, copy, modify, and distribute this
software and its documentation is hereby granted (including for
commercial or for-profit use), provided that both the copyright notice
and this permission notice appear in all copies of the software,
derivative works, or modified versions, and any portions thereof, and
that both notices appear in supporting documentation, and that credit
is given to Carnegie Mellon University in all publications reporting
on direct or indirect use of this code or its derivatives.

ALL CODE, SOFTWARE, PROTOCOLS, AND ARCHITECTURES DEVELOPED BY THE CMU
MONARCH PROJECT ARE EXPERIMENTAL AND ARE KNOWN TO HAVE BUGS, SOME OF
WHICH MAY HAVE SERIOUS CONSEQUENCES. CARNEGIE MELLON PROVIDES THIS
SOFTWARE OR OTHER INTELLECTUAL PROPERTY IN ITS ``AS IS'' CONDITION,
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 CARNEGIE MELLON UNIVERSITY
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 OR
INTELLECTUAL PROPERTY, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
DAMAGE.

Carnegie Mellon encourages (but does not require) users of this
software or intellectual property to return any improvements or
extensions that they make, and to grant Carnegie Mellon the rights to
redistribute these changes without encumbrance.

*/


#include <aodv/aodv.h>
#include <aodv/aodv_packet.h>
#include <ip.h>
#include <random.h>
#include <cmu-trace.h>


#define max(a,b)        a > b ? a : b
#define CURRENT_TIME    Scheduler::instance().clock()

//#define DEBUG

#ifdef DEBUG
static int extra_route_reply = 0;
static int limit_route_request = 0;
static int route_request = 0;
#endif


/* ===================================================================
   TCL Hooks
   ================================================================= */
static class AODVHeaderClass : public PacketHeaderClass {
public:
        AODVHeaderClass() : PacketHeaderClass("PacketHeader/AODV",
                                              AODV_HDR_LEN) { } 
} class_rtProtoAODV_hdr;

static class AODVclass : public TclClass {
public:
        AODVclass() : TclClass("Agent/AODV") {}
        TclObject* create(int argc, const char*const* argv) {
                assert(argc == 5);
                return (new AODV((nsaddr_t) atoi(argv[4])));
        }
} class_rtProtoAODV;



/* ================================================================
   Timers
    ============================================================= */
void
BroadcastTimer::handle(Event*)
{
        agent->id_purge();

        Scheduler::instance().schedule(this, &intr, BCAST_ID_SAVE);
}

void
HelloTimer::handle(Event*)
{
	agent->sendHello();

    double interval = MinHelloInterval +
            ((MaxHelloInterval - MinHelloInterval) * Random::uniform());

    assert(interval >= 0);

    Scheduler::instance().schedule(this, &intr, interval);
}

void
NeighborTimer::handle(Event*)
{
        agent->nb_purge();

        Scheduler::instance().schedule(this, &intr, HELLO_INTERVAL);
}



void
RouteCacheTimer::handle(Event*)
{
        agent->rt_purge();

#define FREQUENCY 0.5 // sec
        Scheduler::instance().schedule(this, &intr, FREQUENCY);
}

void
LocalRepairTimer::handle(Event* p)    // SRD: 5/4/99
{
	rt_entry *rt;

	/* you get here after the timeout in a local repair attempt */
	/*	fprintf(stderr, "%s\n", __FUNCTION__); */

	struct hdr_ip *ih = HDR_IP( (Packet *)p);
	//	rt = agent->rtable.rt_lookup(ih->dst_);

	rt = agent->rtable.rt_lookup(ih->daddr());

	if (rt && rt->rt_flags != RTF_UP) {  // route is yet to be repaired
		// I will be conservative and bring down the route
		// and send triggered replies upstream.

		/* The following assert fails, not sure why */
		/* assert (rt->rt_flags == RTF_IN_REPAIR); */
		
		agent->rt_down(rt);
/* 
 printf("Node %d: Dst - %d, failed local repair\n",index, rt->rt_dst);
*/
	}
	Packet::free((Packet *)p);
}




/*================================================================== */

AODV::AODV(nsaddr_t id) : Agent(PT_AODV),
        btimer(this), htimer(this), ntimer(this), rtimer(this), lrtimer(this),
        rqueue()
{
        bind("off_AODV_", &off_AODV_);
                
        index = id;
        seqno = 1;
        bid = 1;

        LIST_INIT(&nbhead);
        LIST_INIT(&bihead);

        logtarget = 0;
        ifqueue = 0;
}

int
AODV::command(int argc, const char*const* argv)
{
        if(argc == 2) {
                Tcl& tcl = Tcl::instance();

                if(strncasecmp(argv[1], "id", 2) == 0) {
                        tcl.resultf("%d", index);
                        return TCL_OK;
                }
                if(strncasecmp(argv[1], "start", 2) == 0) {
                        btimer.handle((Event*) 0);
#ifndef AODV_LINK_LAYER_DETECTION
                        htimer.handle((Event*) 0);
                        ntimer.handle((Event*) 0);
#endif
                        rtimer.handle((Event*) 0);
                        return TCL_OK;
                }               
        }
        else if(argc == 3) {

                if(strcmp(argv[1], "index") == 0) {
                        index = atoi(argv[2]);
                        return TCL_OK;
                }
                else if(strcmp(argv[1], "log-target") == 0 || strcmp(argv[1], "tracetarget") == 0 ) {
                        logtarget = (Trace*) TclObject::lookup(argv[2]);
                        if(logtarget == 0)
                                return TCL_ERROR;
                        return TCL_OK;
                }
                else if(strcmp(argv[1], "drop-target") == 0) {
		        int stat = rqueue.command(argc,argv);
			if (stat != TCL_OK) return stat;
			return Agent::command(argc, argv);
                }
                else if(strcmp(argv[1], "if-queue") == 0) {
                        ifqueue = (PriQueue*) TclObject::lookup(argv[2]);
                        if(ifqueue == 0)
                                return TCL_ERROR;
                        return TCL_OK;
                }
        }
        return Agent::command(argc, argv);
}


/* =====================================================================
   Neighbor Management Functions
   ===================================================================== */
void
AODV::nb_insert(nsaddr_t id)
{
        Neighbor *nb = new Neighbor(id);
        assert(nb);

        nb->nb_expire = CURRENT_TIME +
                (1.5 * ALLOWED_HELLO_LOSS * HELLO_INTERVAL);
        LIST_INSERT_HEAD(&nbhead, nb, nb_link);
        seqno += 1;             // set of neighbors changed
}


Neighbor*
AODV::nb_lookup(nsaddr_t id)
{
        Neighbor *nb = nbhead.lh_first;

        for(; nb; nb = nb->nb_link.le_next) {
                if(nb->nb_addr == id)
                        break;
        }
        return nb;
}


/*
 * Called when we receive *explicit* notification that a Neighbor
 * is no longer reachable.
 */
void
AODV::nb_delete(nsaddr_t id)
{
        Neighbor *nb = nbhead.lh_first;
        rt_entry *rt;

        log_link_del(id);

        seqno += 1;     // Set of neighbors changed

        for(; nb; nb = nb->nb_link.le_next) {
                if(nb->nb_addr == id) {
                        LIST_REMOVE(nb,nb_link);
                        delete nb;
                        break;
                }
        }

        for(rt = rtable.head(); rt; rt = rt->rt_link.le_next) {
                if(rt->rt_nexthop == id) {
                        rt_down(rt);
                }
        }
}


/*
 * Purges all timed-out Neighbor Entries - runs every
 * HELLO_INTERVAL * 1.5 seconds.
 */
void
AODV::nb_purge()
{
        Neighbor *nb = nbhead.lh_first;
        Neighbor *nbn;
        double now = CURRENT_TIME;

        for(; nb; nb = nbn) {
                nbn = nb->nb_link.le_next;

                if(nb->nb_expire <= now) {
                        nb_delete(nb->nb_addr);
                }
        }
}


/* =====================================================================
   Broadcast ID Management  Functions
   ===================================================================== */

void
AODV::id_insert(nsaddr_t id, u_int32_t bid)
{
        BroadcastID *b = new BroadcastID(id, bid);
        assert(b);

        b->expire = CURRENT_TIME + BCAST_ID_SAVE;
        LIST_INSERT_HEAD(&bihead, b, link);
}

/* I changed this, SRD */
u_int32_t
AODV::id_lookup(nsaddr_t id, u_int32_t bid)
{
        BroadcastID *b = bihead.lh_first;

	// Search the list for a match of source and bid
        for( ; b; b = b->link.le_next) {
                if ((b->src == id) && (b->id == bid))
		  return ID_FOUND;     
        }
        return ID_NOT_FOUND;
}

void
AODV::id_purge()
{
        BroadcastID *b = bihead.lh_first;
        BroadcastID *bn;
        double now = CURRENT_TIME;

        for(; b; b = bn) {
                bn = b->link.le_next;

                if(b->expire <= now) {
                        LIST_REMOVE(b,link);
                        delete b;
                }
        }
}

/* ================================================================= */

static void
aodv_rt_failed_callback(Packet *p, void *arg)
{
        ((AODV*) arg)->rt_ll_failed(p);
}


/*
 * This routine is invoked when the link-layer reports a route failed.
 */
void
AODV::rt_ll_failed(Packet *p)
{
#ifndef AODV_LINK_LAYER_DETECTION
        drop(p, DROP_RTR_MAC_CALLBACK);
#else
        struct hdr_cmn *ch = HDR_CMN(p);
        struct hdr_ip *ih = HDR_IP(p);
        rt_entry *rt;

        /*
         * Non-data packets and Broadcast Packets can be dropped.
         */
        if(! DATA_PACKET(ch->ptype()) ||
	   //           (u_int32_t) ih->dst_ == IP_BROADCAST) {
	   ih->daddr() == (nsaddr_t)IP_BROADCAST) {
                drop(p, DROP_RTR_MAC_CALLBACK);
                return;
        }

        log_link_broke(p);

        // if((rt = rtable.rt_lookup(ih->dst_)) == 0) {
	if((rt = rtable.rt_lookup(ih->daddr())) == 0) {
                drop(p, DROP_RTR_MAC_CALLBACK);
                return;
        }

        log_link_del(ch->next_hop_);

		/* if the broken link is closer to the dest than source, 
		 attempt a local repair. Otherwise, bring down the route. */

#ifdef AODV_LOCAL_REPAIR

		if (ch->num_forwards() > rt->rt_hops) {
			local_rt_repair(rt, p); // local repair
			// Mahesh 09/11/99
			// retrieve all the packets in the ifq using this link,
			// queue the packets for which local repair is done, 
			// drop the rest of the packets and send triggered replies
			return;
		}
		else	
#endif
		{
		  /* Increment the sequence no. and bring down the route */
		  rt->rt_seqno++;
		  rt_down(rt);
		  
		  //		  if (index == ih->src_) {
		  if (index == ih->saddr()) {
		    // If I am the source,
		    // queue the packet since rt_down tries to send a request
		    // Mahesh 09/11/99
		         rqueue.enque(p);
		  }
		  else {
		  	drop(p,DROP_RTR_NO_ROUTE);
		  }
		}


#endif /* AODV_LINK_LAYER_DETECTION */
}


void
AODV::local_rt_repair(rt_entry *rt, Packet *p)
{
  	/* fprintf(stderr,"%s: Dst - %d\n", __FUNCTION__, rt->rt_dst); */

	/* Buffer the packet */
	rqueue.enque(p);

	/* mark the route as under repair */
	rt->rt_flags = RTF_IN_REPAIR;

	/* start a route discovery */
	/* Mahesh 09/11/99
	   Note that the following does not ensure that route request 
	   is actually sent.
	*/
	sendRequest(rt->rt_dst);

	/* set up a timer interrupt */
	Scheduler::instance().schedule(&lrtimer, p->copy(),
						rt->rt_req_timeout);
}



void
AODV::rt_down(rt_entry *rt)
{
	/*
  	 *  Make sure that you don't "down" a route more than once.
  	 */

 	if(rt->rt_flags == RTF_DOWN) {
 		return;
 	}
	/*
	// Mahesh 09/11/99 
	// This function has changed considerably from the last version.
	// Need to check whether the next hop for the destination
	// is changed before bringing down the route, for the time being
	// we ignore this case.
	*/

 	rt->rt_flags = RTF_DOWN;
 	rt->rt_expire = 0;
#ifndef ERROR_BROADCAST
    {
   	Neighbor *nb = rt->rt_nblist.lh_first;
	Neighbor *nbn;

    	for( ; nb; nb = nbn) {
       	 nbn = nb->nb_link.le_next;
		 if (nb->nb_expire > CURRENT_TIME)
		 // If this neighbor is still considered active
	     	sendTriggeredReply(nb->nb_addr,
           		                 rt->rt_dst,
               		             rt->rt_seqno);
            LIST_REMOVE(nb, nb_link);
            delete nb;
     	}
	}
#else
	// Broadcast an unsolicited route reply to the upstream neighbors
	sendTriggeredReply(rt->rt_dst, rt->rt_seqno);
#endif


	/*
	 *  Now purge the Network Interface queues that
	 *  may have packets destined for this broken
	 *  neighbor.
	 */

     {
     Packet *p;

      	 while((p = ifqueue->filter(rt->rt_nexthop))) {
	   //         struct hdr_cmn *ch = HDR_CMN(p);
         struct hdr_ip *ih = HDR_IP(p);         

	 //	     if (index == ih->src_) {
	     if (index == ih->saddr()) {
	       // If I am the source of the packet,
	       // queue this packet and send route request.
	       
            	rqueue.enque(p);
		//                sendRequest(ih->dst_);