dsragent.cc

CBRP协议（移动adhoc中基于分簇的路由协议）ns2下的源码

    { // this must be an outgoing packet, it doesn't have a SR header on it
      srh->init();		 // give packet an SR header now
      cmh->size() += IP_HDR_LEN; // add on IP header size
      if (verbose)
	trace("S %.9f _%s_ originating %s -> %s",
	      Scheduler::instance().clock(), net_id.dump(), p.src.dump(), 
	      p.dest.dump());
      handlePktWithoutSR(p, false);
      goto done;
    }
  else if (p.dest == net_id || p.dest == IP_broadcast)
    { // this packet is intended for us
      handlePacketReceipt(p);
      goto done;
    }
      
  // should we check to see if it's an error packet we're handling
  // and if so call processBrokenRouteError to snoop
  if (dsragent_snoop_forwarded_errors && srh->route_error())
    {
      processBrokenRouteError(p);
    }

  if (srh->route_request())
    { // propagate a route_request that's not for us
      handleRouteRequest(p);
    }
  else
    { // we're not the intended final recpt, but we're a hop
      handleForwarding(p);
    }


done:
  assert(p.pkt == 0);

  p.pkt = 0;
  return;
}


/*===========================================================================
  handlers for each class of packet
---------------------------------------------------------------------------*/
void
DSRAgent::handlePktWithoutSR(SRPacket& p, bool retry)
  /* obtain a source route to p's destination and send it off.
     this should be a retry if the packet is already in the sendbuffer */
{
  hdr_sr *srh =  (hdr_sr*)p.pkt->access(off_sr_);
  assert(srh->valid());

  if (p.dest == net_id)
    { // it doesn't need a source route, 'cause it's for us
      handlePacketReceipt(p);
      return;
    }

  if (route_cache->findRoute(p.dest, p.route, 1))
    { // we've got a route...
      if (verbose)
	trace("S$hit %.5f _%s_ %s -> %s %s",
	      Scheduler::instance().clock(), net_id.dump(),
	      p.src.dump(), p.dest.dump(), p.route.dump());      
      sendOutPacketWithRoute(p, true);
      return;
    } // end if we have a route
  else
    { // we don't have a route...
      if (verbose) 
	trace("S$miss %.5f _%s_ %s -> %s", 
	      Scheduler::instance().clock(), net_id.dump(), 
	      net_id.dump(), p.dest.dump());

      getRouteForPacket(p, retry);
      return;
    } // end of we don't have a route
}

void
DSRAgent::handlePacketReceipt(SRPacket& p)
  /* Handle a packet destined to us */
{
  hdr_sr *srh =  (hdr_sr*)p.pkt->access(off_sr_);

  if (srh->route_reply())
    { // we got a route_reply piggybacked on a route_request
      // accept the new source route before we do anything else
      // (we'll send off any packet's we have queued and waiting)
      acceptRouteReply(p);
    }
  
  if (srh->route_request())
    {
      if (dsragent_reply_only_to_first_rtreq  && ignoreRouteRequestp(p)) 
	{ //we only respond to the first route request
	  // we receive from a host 
	  Packet::free(p.pkt);     // drop silently
	  p.pkt = 0;
	  return;
	}
      else
	{ // we're going to process this request now, so record the req_num
	  request_table.insert(p.src, p.src, srh->rtreq_seq());
	  returnSrcRouteToRequestor(p);
	}
    }

  if (srh->route_error())
    { // register the dead route      
      processBrokenRouteError(p);
    }

  /* give the data in the packet to our higher layer (our port dmuxer, most 
   likely) */
  assert(p.dest == net_id || p.dest == MAC_id);
  target_->recv(p.pkt, (Handler*)0);
  p.pkt = 0;
}

void
DSRAgent::handleForwarding(SRPacket &p)
  /* forward packet on to next host in source route,
   snooping as appropriate */
{
  hdr_sr *srh =  (hdr_sr*)p.pkt->access(off_sr_);
  hdr_cmn *cmh =  (hdr_cmn*)p.pkt->access(off_cmn_);

  trace("SF %.9f _%s_ --- %d [%s -> %s] %s", 
	Scheduler::instance().clock(), net_id.dump(), cmh->uid(),
	p.src.dump(), p.dest.dump(), srh->dump());

  // first make sure we are the ``current'' host along the source route.
  // if we're not, the previous node set up the source route incorrectly.
  assert(p.route[p.route.index()] == net_id
	 || p.route[p.route.index()] == MAC_id);

  if (p.route.index() >= p.route.length())
    {
      fprintf(stderr,"dfu: ran off the end of a source route\n");
      trace("SDFU:  ran off the end of a source route\n");
      drop(p.pkt, DROP_RTR_ROUTE_LOOP);
      p.pkt = 0;
      // maybe we should send this packet back as an error...
      return;
    }

  // if there's a source route, maybe we should snoop it too
  if (dsragent_snoop_source_routes)
    route_cache->noticeRouteUsed(p.route, Scheduler::instance().clock(), 
				 net_id);

  // sendOutPacketWithRoute will add in the size of the src hdr, so
  // we have to subtract it out here
  struct hdr_cmn *ch = HDR_CMN(p.pkt);
  ch->size() -= srh->size();

  // now forward the packet...
  sendOutPacketWithRoute(p, false);
}

void
DSRAgent::handleRouteRequest(SRPacket &p)
  /* process a route request that isn't targeted at us */
{
  hdr_sr *srh =  (hdr_sr*)p.pkt->access(off_sr_);
  assert (srh->route_request());

  if (ignoreRouteRequestp(p)) 
    {
      if (verbose_srr) 
        trace("SRR %.5f _%s_ dropped %s #%d (ignored)",
              Scheduler::instance().clock(), net_id.dump(), p.src.dump(),
              srh->rtreq_seq());
      Packet::free(p.pkt);  // pkt is a route request we've already processed
      p.pkt = 0;
      return; // drop silently
    }

  // we're going to process this request now, so record the req_num
  request_table.insert(p.src, p.src, srh->rtreq_seq());

  /*  - if it's a Ring 0 search, check the rt$ for a reply and use it if
     possible.  There's not much point in doing Ring 0 search if you're 
     not going to check the cache.  See the comment about turning off all
     reply from cache behavior near the definition of d_r_f_c_o_p (if your 
     workload had really good spatial locality, it might still make 
     sense 'cause your target is probably sitting next to you)
      - if reply from cache is on, check the cache and reply if possible
      - otherwise, just propagate if possible. */
  if ((srh->max_propagation() == 0 || dsragent_reply_from_cache_on_propagating)
      && replyFromRouteCache(p))
    return;			// all done

  // does the orginator want us to propagate?
  if (p.route.length() > srh->max_propagation())
    { 	// no propagation
      if (verbose_srr) 
        trace("SRR %.5f _%s_ dropped %s #%d (prop limit exceeded)",
              Scheduler::instance().clock(), net_id.dump(), p.src.dump(),
              srh->rtreq_seq());
      Packet::free(p.pkt); // pkt isn't for us, and isn't data carrying
      p.pkt = 0;
      return;		
    }

  // can we propagate?
  if (p.route.full())
    { 	// no propagation
      trace("SRR %.5f _%s_ dropped %s #%d (SR full)",
            Scheduler::instance().clock(), net_id.dump(), p.src.dump(),
	    srh->rtreq_seq());
      /* pkt is a rt req, even if data carrying, we don't want to log 
	 the drop using drop() since many nodes could be dropping the 
	 packet in this fashion */
      Packet::free(p.pkt);
      p.pkt = 0;
      return;		
    }

  // add ourselves to the source route
  p.route.appendToPath(net_id);

  if (verbose_srr)
    trace("SRR %.5f _%s_ rebroadcast %s #%d ->%s %s",
          Scheduler::instance().clock(), net_id.dump(), p.src.dump(),
          srh->rtreq_seq(), p.dest.dump(), p.route.dump());

  sendOutPacketWithRoute(p, false);
  return;      
}

/*===========================================================================
  Helpers
---------------------------------------------------------------------------*/
bool
DSRAgent::ignoreRouteRequestp(SRPacket &p)
// should we ignore this route request?
{
  hdr_sr *srh =  (hdr_sr*)p.pkt->access(off_sr_);

  if (request_table.get(p.src) >= srh->rtreq_seq())
    { // we've already processed a copy of this reqest so
      // we should drop the request silently
      return true;
    }
  if (p.route.member(net_id,MAC_id))
    { // we're already on the route, drop silently
      return true;
    }

  if (p.route.full())
    { // there won't be room for us to put our address into
      // the route
      // so drop silently - sigh, so close, and yet so far...
      // Note that since we don't record the req_id of this message yet,
      // we'll process the request if it gets to us on a shorter path
      return true;
    }
  return false;
}


bool
DSRAgent::replyFromRouteCache(SRPacket &p)
  /* - see if can reply to this route request from our cache
     if so, do it and return true, otherwise, return false 
     - frees or hands off p iff returns true */
{
  Path rest_of_route;
  Path complete_route = p.route;

  /* we shouldn't yet be on on the pkt's current source route */
  assert(!p.route.member(net_id, MAC_id));

  // do we have a cached route the target?
  /* XXX what if we have more than 1?  (and one is legal for reply from
     cache and one isn't?) 1/28/97 -dam */
  if (!route_cache->findRoute(p.dest, rest_of_route, 0))
    { // no route => we're done
      return false;
    }

  /* but we should be on on the remainder of the route (and should be at
   the start of the route */
  assert(rest_of_route[0] == net_id || rest_of_route[0] == MAC_id);

  if (rest_of_route.length() + p.route.length() > MAX_SR_LEN)
    return false; // too long to work with...

  // add our suggested completion to the route so far
  complete_route.appendPath(rest_of_route);

  // call compressPath to remove any double backs
  ::compressPath(complete_route);

  if (!complete_route.member(net_id, MAC_id))
    { // we're not on the suggested route, so we can't return it
      return false;
    }

  // if there is any other information piggybacked into the
  // route request pkt, we need to forward it on to the dst
  hdr_cmn *cmh =  (hdr_cmn*)p.pkt->access(off_cmn_);
  hdr_sr *srh =  (hdr_sr*)p.pkt->access(off_sr_);
  int request_seqnum = srh->rtreq_seq();
  
  if (PT_DSR != cmh->ptype()	// there's data
      || srh->route_reply()
      || (srh->route_error() && 
	  srh->down_links()[srh->num_route_errors()-1].tell_addr 
	  != GRAT_ROUTE_ERROR))
    { // must forward the packet on
      SRPacket p_copy = p;
      p.pkt = 0;
      srh->route_request() = 0;

      p_copy.route = complete_route;
      p_copy.route.setIterator(p.route.length());

      assert(p.route[p.route.index()] == net_id);
      
      if (verbose) trace("Sdebug %.9f _%s_ splitting %s to %s",
                         Scheduler::instance().clock(), net_id.dump(),
                         p.route.dump(), p_copy.route.dump());

      sendOutPacketWithRoute(p_copy,false);
    }
  else 
    {
      Packet::free(p.pkt);  // free the rcvd rt req before making rt reply
      p.pkt = 0;
    }

  // make up and send out a route reply
  p.route.appendToPath(net_id);
  p.route.reverseInPlace();
  route_cache->addRoute(p.route, Scheduler::instance().clock(), net_id);
  p.dest = p.src;
  p.src = net_id;
  p.pkt = allocpkt();

  hdr_ip *iph =  (hdr_ip*)p.pkt->access(off_ip_);
  iph->src() = p.src.addr;
  iph->sport() = RT_PORT;
  iph->dst() = p.dest.addr;
  iph->dport() = RT_PORT;
  iph->ttl() = 255;

  srh = (hdr_sr*)p.pkt->access(off_sr_);
  srh->init();
  for (int i = 0 ; i < complete_route.length() ; i++)
    complete_route[i].fillSRAddr(srh->reply_addrs()[i]);
  srh->route_reply_len() = complete_route.length();
  srh->route_reply() = 1;

  // propagate the request sequence number in the reply for analysis purposes
  srh->rtreq_seq() = request_seqnum;

  hdr_cmn *cmnh =  (hdr_cmn*)p.pkt->access(off_cmn_);
  cmnh->ptype() = PT_DSR;
  cmnh->size() = IP_HDR_LEN;

  trace("SRR %.9f _%s_ cache-reply-sent %s -> %s #%d (len %d) %s",
	Scheduler::instance().clock(), net_id.dump(),
	p.src.dump(), p.dest.dump(), request_seqnum, complete_route.length(),
	complete_route.dump());
  sendOutPacketWithRoute(p, true);
  return true;
}


void
DSRAgent::sendOutPacketWithRoute(SRPacket& p, bool fresh, Time delay = 0.0)
     // take packet and send it out, packet must a have a route in it
     // return value is not very meaningful
     // if fresh is true then reset the path before using it, if fresh
     //  is false then our caller wants us use a path with the index
     //  set as it currently is
{
  hdr_sr *srh =  (hdr_sr*)p.pkt->access(off_sr_);
  hdr_cmn *cmnh = (hdr_cmn*)p.pkt->access(off_cmn_);

  assert(srh->valid());
  assert(cmnh->size() > 0);

  if (p.dest == net_id)
    { // it doesn't need to go on the wire, 'cause it's for us
      recv(p.pkt, (Handler *) 0);
      p.pkt = 0;
      return;
    }

  if (fresh)
    {
      p.route.resetIterator();
      if (verbose && !srh->route_request())
	{
	  trace("SO %.9f _%s_ originating %s %s", 
		Scheduler::instance().clock(), 
		net_id.dump(), packet_names[cmnh->ptype()], p.route.dump());
	}
    }
  p.route.fillSR(srh);
  cmnh->size() += srh->size();

  if (srh->route_request())
    { // broadcast forward
      cmnh->xmit_failure_ = 0;
      cmnh->next_hop() = MAC_BROADCAST;
      cmnh->addr_type() = AF_LINK;
    }
  else
    { // forward according to source route
      cmnh->xmit_failure_ = XmitFailureCallback;
      cmnh->xmit_failure_data_ = (void *) this;

      cmnh->next_hop() = srh->get_next_addr();
      cmnh->addr_type() = srh->get_next_type();
      srh->cur_addr() = srh->cur_addr() + 1;
    }

  /* put route errors at the head of the ifq somehow? -dam 4/13/98 */

  // make sure we aren't cycling packets
  assert(p.pkt->incoming == 0); // this is an outgoing packet

  if (ifq->length() > 25)
    trace("SIFQ %.5f _%s_ len %d",
          Scheduler::instance().clock(), net_id.dump(), ifq->length());

  // off it goes!
  if (srh->route_request())
    { // route requests need to be jittered a bit
      Scheduler::instance().schedule(ll, p.pkt, 
				     Random::uniform(RREQ_JITTER) + delay);
    }
  else
    { // no jitter required 
      Scheduler::instance().schedule(ll, p.pkt, delay);
    }
  p.pkt = NULL; /* packet sent off */
}

void
DSRAgent::getRouteForPacket(SRPacket &p, bool retry)
  /* try to obtain a route for packet
     pkt is freed or handed off as needed, unless retry == true
     in which case it is not touched */
{
  // since we'll commonly be only one hop away, we should
  // arp first before route discovery as an optimization...

  Entry *e = request_table.getEntry(p.dest);
  Time time = Scheduler::instance().clock();
  
  /* for now, no piggybacking at all, queue all pkts */
  if (!retry) 
    {
      stickPacketInSendBuffer(p);
      p.pkt = 0; // pkt is handled for now (it's in sendbuffer)
    }

#if 0
  /* pre 4/13/98 logic -dam removed b/c it seemed more complicated than
     needed since we're not doing piggybacking and we're returning
     route replies via a reversed route (the copy in this code is
     critical if we need to piggyback route replies on the route request to
     discover the return path) */

  /* make the route request packet */
  SRPacket rrp = p;
  rrp.pkt = p.pkt->copy();
  hdr_sr *srh =  (hdr_sr*)rrp.pkt->access(off_sr_);
  hdr_ip *iph =  (hdr_ip*)rrp.pkt->access(off_ip_);