aodv.c

这个软件提供了ns AODV路由的最新代码。欢迎研究AD HOC的共勉。

   forward(rt, p, NO_DELAY);
 }
 /*
  *  if I am the source of the packet, then do a Route Request.
  */
	else if(ih->saddr() == index) {
   rqueue.enque(p);
   sendRequest(rt->rt_dst);
 }
 /*
  *	A local repair is in progress. Buffer the packet. 
  */
 else if (rt->rt_flags == RTF_IN_REPAIR) {
   rqueue.enque(p);
 }

 /*
  * I am trying to forward a packet for someone else to which
  * I don't have a route.
  */
 else {
 Packet *rerr = Packet::alloc();
 struct hdr_aodv_error *re = HDR_AODV_ERROR(rerr);
 /* 
  * For now, drop the packet and send error upstream.
  * Now the route errors are broadcast to upstream
  * neighbors - Mahesh 09/11/99
  */	
 
   assert (rt->rt_flags == RTF_DOWN);
   re->DestCount = 0;
   re->unreachable_dst[re->DestCount] = rt->rt_dst;
   re->unreachable_dst_seqno[re->DestCount] = rt->rt_seqno;
   re->DestCount += 1;
#ifdef DEBUG
   fprintf(stderr, "%s: sending RERR...\n", __FUNCTION__);
#endif
   sendError(rerr, false);

   drop(p, DROP_RTR_NO_ROUTE);
 }

}

void
AODV::rt_purge() {
aodv_rt_entry *rt, *rtn;
double now = CURRENT_TIME;
double delay = 0.0;
Packet *p;

 for(rt = rtable.head(); rt; rt = rtn) {  // for each rt entry
   rtn = rt->rt_link.le_next;
   if ((rt->rt_flags == RTF_UP) && (rt->rt_expire < now)) {
   // if a valid route has expired, purge all packets from 
   // send buffer and invalidate the route.                    
	assert(rt->rt_hops != INFINITY2);
     while((p = rqueue.deque(rt->rt_dst))) {
#ifdef DEBUG
       fprintf(stderr, "%s: calling drop()\n",
                       __FUNCTION__);
#endif // DEBUG
       drop(p, DROP_RTR_NO_ROUTE);
     }
     rt->rt_seqno++;
     assert (rt->rt_seqno%2);
     rt_down(rt);
   }
   else if (rt->rt_flags == RTF_UP) {
   // If the route is not expired,
   // and there are packets in the sendbuffer waiting,
   // forward them. This should not be needed, but this extra 
   // check does no harm.
     assert(rt->rt_hops != INFINITY2);
     while((p = rqueue.deque(rt->rt_dst))) {
       forward (rt, p, delay);
       delay += ARP_DELAY;
     }
   } 
   else if (rqueue.find(rt->rt_dst))
   // If the route is down and 
   // if there is a packet for this destination waiting in
   // the sendbuffer, then send out route request. sendRequest
   // will check whether it is time to really send out request
   // or not.
   // This may not be crucial to do it here, as each generated 
   // packet will do a sendRequest anyway.

     sendRequest(rt->rt_dst); 
   }

}

/*
  Packet Reception Routines
*/

void
AODV::recv(Packet *p, Handler*) {
struct hdr_cmn *ch = HDR_CMN(p);
struct hdr_ip *ih = HDR_IP(p);

 assert(initialized());
 //assert(p->incoming == 0);
 // XXXXX NOTE: use of incoming flag has been depracated; In order to track direction of pkt flow, direction_ in hdr_cmn is used instead. see packet.h for details.

 if(ch->ptype() == PT_AODV) {
   ih->ttl_ -= 1;
   recvAODV(p);
   return;
 }

 /*
  *  Must be a packet I'm originating...
  */
if((ih->saddr() == index) && (ch->num_forwards() == 0)) {
 /*
  * Add the IP Header
  */
   ch->size() += IP_HDR_LEN;
   // Added by Parag Dadhania && John Novatnack to handle broadcasting
   if ( (u_int32_t)ih->daddr() != IP_BROADCAST)
     ih->ttl_ = NETWORK_DIAMETER;
}
 /*
  *  I received a packet that I sent.  Probably
  *  a routing loop.
  */
else if(ih->saddr() == index) {
   drop(p, DROP_RTR_ROUTE_LOOP);
   return;
 }
 /*
  *  Packet I'm forwarding...
  */
 else {
 /*
  *  Check the TTL.  If it is zero, then discard.
  */
   if(--ih->ttl_ == 0) {
     drop(p, DROP_RTR_TTL);
     return;
   }
 }
// Added by Parag Dadhania && John Novatnack to handle broadcasting
 if ( (u_int32_t)ih->daddr() != IP_BROADCAST)
   rt_resolve(p);
 else
   forward((aodv_rt_entry*) 0, p, NO_DELAY);
}


void
AODV::recvAODV(Packet *p) {
struct hdr_aodv *ah = HDR_AODV(p);
struct hdr_ip *ih = HDR_IP(p);

 assert(ih->sport() == RT_PORT);
 assert(ih->dport() == RT_PORT);

 /*
  * Incoming Packets.
  */
 switch(ah->ah_type) {

 case AODVTYPE_RREQ:
   recvRequest(p);
   break;

 case AODVTYPE_RREP:
   recvReply(p);
   break;

 case AODVTYPE_RERR:
   recvError(p);
   break;

 case AODVTYPE_HELLO:
   recvHello(p);
   break;
        
 default:
   fprintf(stderr, "Invalid AODV type (%x)\n", ah->ah_type);
   exit(1);
 }

}


void
AODV::recvRequest(Packet *p) {
struct hdr_ip *ih = HDR_IP(p);
struct hdr_aodv_request *rq = HDR_AODV_REQUEST(p);
aodv_rt_entry *rt;

  /*
   * Drop if:
   *      - I'm the source
   *      - I recently heard this request.
   */

  if(rq->rq_src == index) {
#ifdef DEBUG
    fprintf(stderr, "%s: got my own REQUEST\n", __FUNCTION__);
#endif // DEBUG
    Packet::free(p);
    return;
  } 

 if (id_lookup(rq->rq_src, rq->rq_bcast_id)) {

#ifdef DEBUG
   fprintf(stderr, "%s: discarding request\n", __FUNCTION__);
#endif // DEBUG
 
   Packet::free(p);
   return;
 }

 /*
  * Cache the broadcast ID
  */
 id_insert(rq->rq_src, rq->rq_bcast_id);



	/* 
	* We are either going to forward the REQUEST or generate a
	* REPLY. Before we do anything, we make sure that the REVERSE
	* route is in the route table.
	*/
   aodv_rt_entry *rt0; // rt0 is the reverse route 
   
   rt0 = rtable.rt_lookup(rq->rq_src);
   if(rt0 == 0) { /* if not in the route table */
   // create an entry for the reverse route.
     rt0 = rtable.rt_add(rq->rq_src);
   }
  
   rt0->rt_expire = max(rt0->rt_expire, (CURRENT_TIME + REV_ROUTE_LIFE));

   if ( (rq->rq_src_seqno > rt0->rt_seqno ) ||((rq->rq_src_seqno == rt0->rt_seqno) && 
	 (rq->rq_hop_count < rt0->rt_hops)) ) {
		// If we have a fresher seq no. or lesser #hops for the 
		// same seq no., update the rt entry. Else don't bother.
		rt_update(rt0, rq->rq_src_seqno, rq->rq_hop_count, ih->saddr(),max(rt0->rt_expire, 
			(CURRENT_TIME + REV_ROUTE_LIFE)) );
		if (rt0->rt_req_timeout > 0.0) {
			// Reset the soft state and 
			// Set expiry time to CURRENT_TIME + ACTIVE_ROUTE_TIMEOUT
			// This is because route is used in the forward direction,
			// but only sources get benefited by this change
			rt0->rt_req_cnt = 0;
			rt0->rt_req_timeout = 0.0; 
			rt0->rt_req_last_ttl = rq->rq_hop_count;
			rt0->rt_expire = CURRENT_TIME + ACTIVE_ROUTE_TIMEOUT;
		}

		/* Find out whether any buffered packet can benefit from the 
		* reverse route.
		* May need some change in the following code - Mahesh 09/11/99
		*/
		assert (rt0->rt_flags == RTF_UP);
		Packet *buffered_pkt;
		while ((buffered_pkt = rqueue.deque(rt0->rt_dst))) {
			if (rt0 && (rt0->rt_flags == RTF_UP)) {
				assert(rt0->rt_hops != INFINITY2);
				forward(rt0, buffered_pkt, NO_DELAY);
			}
		}
   } 
   // End for putting reverse route in rt table


 /*
  * We have taken care of the reverse route stuff.
  * Now see whether we can send a route reply. 
  */

 rt = rtable.rt_lookup(rq->rq_dst);

 // First check if I am the destination ..

 if(rq->rq_dst == index) {

#ifdef DEBUG
   fprintf(stderr, "%d - %s: destination sending reply\n",
                   index, __FUNCTION__);
#endif // DEBUG

               
   // Just to be safe, I use the max. Somebody may have
   // incremented the dst seqno.
   seqno = max(seqno, rq->rq_dst_seqno)+1;
   if (seqno%2) seqno++;

   sendReply(rq->rq_src,           // IP Destination
             1,                    // Hop Count
             index,                // Dest IP Address
             seqno,                // Dest Sequence Num
             MY_ROUTE_TIMEOUT,     // Lifetime
             rq->rq_timestamp);    // timestamp
 
   Packet::free(p);
 }

 // I am not the destination, but I may have a fresh enough route.

 else if (rt && (rt->rt_hops != INFINITY2) && (rt->rt_seqno >= rq->rq_dst_seqno) ) {

   //assert (rt->rt_flags == RTF_UP);
   assert(rq->rq_dst == rt->rt_dst);
   //assert ((rt->rt_seqno%2) == 0);	// is the seqno even?
   sendReply(rq->rq_src,
             rt->rt_hops + 1,
             rq->rq_dst,
             rt->rt_seqno,
			(u_int32_t) (rt->rt_expire - CURRENT_TIME),
	     // rt->rt_expire - CURRENT_TIME,
             rq->rq_timestamp);
   // Insert nexthops to RREQ source and RREQ destination in the
   // precursor lists of destination and source respectively
   rt->pc_insert(rt0->rt_nexthop); // nexthop to RREQ source
   rt0->pc_insert(rt->rt_nexthop); // nexthop to RREQ destination

#ifdef RREQ_GRAT_RREP  

   sendReply(rq->rq_dst,
             rq->rq_hop_count,
             rq->rq_src,
             rq->rq_src_seqno,
	     (u_int32_t) (rt->rt_expire - CURRENT_TIME),
	     //             rt->rt_expire - CURRENT_TIME,
             rq->rq_timestamp);
#endif
   
// TODO: send grat RREP to dst if G flag set in RREQ using rq->rq_src_seqno, rq->rq_hop_counT
   
// DONE: Included gratuitous replies to be sent as per IETF aodv draft specification. As of now, G flag has not been dynamically used and is always set or reset in aodv-packet.h --- Anant Utgikar, 09/16/02.

	Packet::free(p);
 }
 /*
  * Can't reply. So forward the  Route Request
  */
 else {
   ih->saddr() = index;
   ih->daddr() = IP_BROADCAST;
   rq->rq_hop_count += 1;
   // Maximum sequence number seen en route
   if (rt) rq->rq_dst_seqno = max(rt->rt_seqno, rq->rq_dst_seqno);
   forward((aodv_rt_entry*) 0, p, DELAY);
 }

}


void
AODV::recvReply(Packet *p) {
//struct hdr_cmn *ch = HDR_CMN(p);
struct hdr_ip *ih = HDR_IP(p);
struct hdr_aodv_reply *rp = HDR_AODV_REPLY(p);
aodv_rt_entry *rt;
char suppress_reply = 0;
double delay = 0.0;
	
#ifdef DEBUG
 fprintf(stderr, "%d - %s: received a REPLY\n", index, __FUNCTION__);
#endif // DEBUG


 /*
  *  Got a reply. So reset the "soft state" maintained for 
  *  route requests in the request table. We don't really have
  *  have a separate request table. It is just a part of the
  *  routing table itself. 
  */
 // Note that rp_dst is the dest of the data packets, not the
 // the dest of the reply, which is the src of the data packets.

 rt = rtable.rt_lookup(rp->rp_dst);
        
 /*
  *  If I don't have a rt entry to this host... adding
  */
 if(rt == 0) {
   rt = rtable.rt_add(rp->rp_dst);
 }

 /*
  * Add a forward route table entry... here I am following 
  * Perkins-Royer AODV paper almost literally - SRD 5/99
  */

 if ( (rt->rt_seqno < rp->rp_dst_seqno) ||   // newer route 
      ((rt->rt_seqno == rp->rp_dst_seqno) &&  
       (rt->rt_hops > rp->rp_hop_count)) ) { // shorter or better route
	
  // Update the rt entry 
  rt_update(rt, rp->rp_dst_seqno, rp->rp_hop_count,
		rp->rp_src, CURRENT_TIME + rp->rp_lifetime);

  // reset the soft state
  rt->rt_req_cnt = 0;
  rt->rt_req_timeout = 0.0; 
  rt->rt_req_last_ttl = rp->rp_hop_count;
  
if (ih->daddr() == index) { // If I am the original source
  // Update the route discovery latency statistics
  // rp->rp_timestamp is the time of request origination
		
    rt->rt_disc_latency[rt->hist_indx] = (CURRENT_TIME - rp->rp_timestamp)
                                         / (double) rp->rp_hop_count;
    // increment indx for next time
    rt->hist_indx = (rt->hist_indx + 1) % MAX_HISTORY;
  }	

  /*
   * Send all packets queued in the sendbuffer destined for
   * this destination. 
   * XXX - observe the "second" use of p.
   */
  Packet *buf_pkt;
  while((buf_pkt = rqueue.deque(rt->rt_dst))) {
    if(rt->rt_hops != INFINITY2) {
          assert (rt->rt_flags == RTF_UP);
    // Delay them a little to help ARP. Otherwise ARP 
    // may drop packets. -SRD 5/23/99
      forward(rt, buf_pkt, delay);
      delay += ARP_DELAY;
    }
  }
 }
 else {
  suppress_reply = 1;
 }

 /*
  * If reply is for me, discard it.
  */

if(ih->daddr() == index || suppress_reply) {
   Packet::free(p);
 }
 /*
  * Otherwise, forward the Route Reply.
  */
 else {
 // Find the rt entry
aodv_rt_entry *rt0 = rtable.rt_lookup(ih->daddr());
   // If the rt is up, forward
   if(rt0 && (rt0->rt_hops != INFINITY2)) {
        assert (rt0->rt_flags == RTF_UP);
     rp->rp_hop_count += 1;
     rp->rp_src = index;
     forward(rt0, p, NO_DELAY);
     // Insert the nexthop towards the RREQ source to 
     // the precursor list of the RREQ destination
     rt->pc_insert(rt0->rt_nexthop); // nexthop to RREQ source
     
   }