dsragent.cc

动态路由协议dsr改进算法

      p.route.index() - amt > 0) {
    trace("SFARS %.9f _%s_ %d [%s -> %s] %d %d", 
	  Scheduler::instance().clock(), net_id.dump(), cmnh->uid(),
	  p.src.dump(), p.dest.dump(), flow_table[flowidx].flowId, amt);

    // stamp a route in the packet...
    p.route = flow_table[flowidx].sourceRoute;
    p.route.index() -= amt;
    sendRouteShortening(p, p.route.index(), 
			flow_table[flowidx].sourceRoute.index());
  }

  if (dsragent_always_reestablish) {
    // XXX this is an utter hack. the flow_table needs to remember the original
    // timeout value specified, as well as the original time to timeout. No
    // establishment packets are allowed after the original time. Must make sure
    // flowids assigned do not overlap. ych 5/8/01
    flow_table[flowidx].timeout = Scheduler::instance().clock() + 
				  default_flow_timeout;
  }
  // set the direction pkt to be down
  cmnh->direction() = hdr_cmn::DOWN;
  Scheduler::instance().schedule(ll, p.pkt, 0);
  p.pkt = 0;
}

void
DSRAgent::handleFlowForwarding(SRPacket &p) {
  hdr_sr *srh = hdr_sr::access(p.pkt);
  hdr_ip *iph = hdr_ip::access(p.pkt);
  int flowidx = flow_table.find(p.src.addr, p.dest.addr, srh->flow_id());

  assert(srh->flow_header());

  if (srh->num_addrs()) {
    assert(srh->flow_timeout());

    if (flowidx == -1) {
      flow_table.cleanup();
      flowidx = flow_table.createEntry(p.src.addr, p.dest.addr, srh->flow_id());

      assert(flowidx != -1);

      flow_table[flowidx].timeout = Scheduler::instance().clock() + 
				    srh->flow_timeout_time();
      flow_table[flowidx].hopCount = srh->hopCount();
      flow_table[flowidx].expectedTTL = iph->ttl();
      flow_table[flowidx].sourceRoute = p.route;
      flow_table[flowidx].nextHop = srh->get_next_addr();
      assert(srh->hopCount() == srh->cur_addr());
      assert(srh->get_next_type() == ::IP);
      assert(flow_table[flowidx].sourceRoute[flow_table[flowidx].hopCount] == 
	     net_id);

      flow_table[flowidx].count = 0;            // shouldn't be used
      flow_table[flowidx].allowDefault = false; // shouldn't be used
    }

    assert(flowidx != -1);
    //assert(flow_table[flowidx].hopCount == srh->hopCount());
    
    srh->hopCount()++;
    return;
  }

  if (flowidx == -1) {
    // return an error
    sendUnknownFlow(p, false, srh->flow_id());
    assert(p.pkt == 0);
    return;
  }

  //assert(flow_table[flowidx].hopCount == srh->hopCount());

  srh->hopCount()++;

  // forward the packet
  handleFlowForwarding(p, flowidx);
}

void
DSRAgent::handleForwarding(SRPacket &p)
  /* forward packet on to next host in source route,
   snooping as appropriate */
{
  hdr_sr *srh =  hdr_sr::access(p.pkt);
  hdr_ip *iph = hdr_ip::access(p.pkt);
  hdr_cmn *ch =  hdr_cmn::access(p.pkt);
  bool flowOnly = !srh->num_addrs();

  if (srh->flow_header())
    handleFlowForwarding(p);
  else if (!srh->num_addrs())
    handleDefaultForwarding(p);

  if (flowOnly)
    return;

  assert(p.pkt); // make sure flow state didn't eat the pkt

  // 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
  ch->size() -= srh->size();

  // we need to manually decr this, since nothing else does.
  if (!iph->ttl()--) {
    drop(p.pkt, DROP_RTR_TTL);
    p.pkt = 0;
    return;
  }

  // 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::access(p.pkt);
  assert (srh->route_request());

#ifdef notdef
  {
          int src = mac_->hdr_src(HDR_MAC(p.pkt));

          if(mac_->is_neighbor(src) == 0) {
                  Packet::free(p.pkt);
                  p.pkt = 0;
                  return;
          }
  }
#endif

  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

#ifdef NEW_REQUEST_LOGIC
  /*
   * If we are congested, don't forward or answer the Route Reply
   */
  if(ifq->prq_length() > 10) {
	  trace("SRR %.9f _%s_ discarding %s #%d (ifq length %d)",
		Scheduler::instance().clock(),
		net_id.dump(),
		p.src.dump(),
		srh->rtreq_seq(),
		ifq->prq_length());
	  Packet::free(p.pkt);
	  p.pkt = 0;
	  return;
  }

  /*
   *  If "free air time" < 15%, don't forward or answer the Route Reply
   */
  {
	  double atime = mac_->air_time_free(10);

	  if(atime > 0.0 && atime < 0.15) {
		  trace("SRR %.9f _%s_ discarding %s #%d (free air time %f)",
			Scheduler::instance().clock(),
			net_id.dump(),
			p.src.dump(),
			srh->rtreq_seq(),
			atime);
		  Packet::free(p.pkt);
		  p.pkt = 0;
		  return;
	  }
  }  
#endif /* NEW_REQUEST_LOGIC */

  // 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::access(p.pkt);

  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::access(p.pkt);
  hdr_sr *srh =  hdr_sr::access(p.pkt);
  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::access(p.pkt);
  iph->saddr() = Address::instance().create_ipaddr(p.src.addr, RT_PORT);
  iph->sport() = RT_PORT;
  iph->daddr() = Address::instance().create_ipaddr(p.dest.addr, RT_PORT);
  iph->dport() = RT_PORT;
  iph->ttl() = 255;

  srh = hdr_sr::access(p.pkt);
  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::access(p.pkt);
  cmnh->ptype() = PT_DSR;
  cmnh->size() = IP_HDR_LEN;

  if (verbose_srr)
    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)
     // 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::access(p.pkt);
  hdr_cmn *cmnh = hdr_cmn::access(p.pkt);

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

  ID dest;
  if (diff_subnet(p.dest,net_id)) {
  dest = ID(node_->base_stn(),::IP);
  p.dest = dest;
  }

  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)
    {