FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_dummynet.c

     /*
      * Copyright (c) 1998-2002 Luigi Rizzo, Universita` di Pisa
      * Portions Copyright (c) 2000 Akamba Corp.
      * All rights reserved
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' 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 THE AUTHOR OR CONTRIBUTORS 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, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD: releng/5.2/sys/netinet/ip_dummynet.c 123169 2003-12-06 09:01:25Z emax $
     */
    
    #define DUMMYNET_DEBUG
    
    /*
     * This module implements IP dummynet, a bandwidth limiter/delay emulator
     * used in conjunction with the ipfw package.
     * Description of the data structures used is in ip_dummynet.h
     * Here you mainly find the following blocks of code:
     *  + variable declarations;
     *  + heap management functions;
     *  + scheduler and dummynet functions;
     *  + configuration and initialization.
     *
     * NOTA BENE: critical sections are protected by the "dummynet lock".
     *
     * Most important Changes:
     *
     * 011004: KLDable
     * 010124: Fixed WF2Q behaviour
     * 010122: Fixed spl protection.
     * 000601: WF2Q support
     * 000106: large rewrite, use heaps to handle very many pipes.
     * 980513:      initial release
     *
     * include files marked with XXX are probably not needed
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/proc.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/time.h>
    #include <sys/sysctl.h>
    #include <net/if.h>
    #include <net/route.h>
    #include <netinet/in.h>
    #include <netinet/in_systm.h>
    #include <netinet/in_var.h>
    #include <netinet/ip.h>
    #include <netinet/ip_fw.h>
    #include <netinet/ip_dummynet.h>
    #include <netinet/ip_var.h>
    
    #include <netinet/if_ether.h> /* for struct arpcom */
    #include <net/bridge.h>
    
    /*
     * We keep a private variable for the simulation time, but we could
     * probably use an existing one ("softticks" in sys/kern/kern_timer.c)
     */
    static dn_key curr_time = 0 ; /* current simulation time */
    
    static int dn_hash_size = 64 ;  /* default hash size */
    
    /* statistics on number of queue searches and search steps */
    static int searches, search_steps ;
    static int pipe_expire = 1 ;   /* expire queue if empty */
    static int dn_max_ratio = 16 ; /* max queues/buckets ratio */
    
    static int red_lookup_depth = 256;      /* RED - default lookup table depth */
    static int red_avg_pkt_size = 512;      /* RED - default medium packet size */
    static int red_max_pkt_size = 1500;     /* RED - default max packet size */
    
    /*
     * Three heaps contain queues and pipes that the scheduler handles:
     *
    * ready_heap contains all dn_flow_queue related to fixed-rate pipes.
    *
    * wfq_ready_heap contains the pipes associated with WF2Q flows
    *
    * extract_heap contains pipes associated with delay lines.
    *
    */
   
   MALLOC_DEFINE(M_DUMMYNET, "dummynet", "dummynet heap");
   
   static struct dn_heap ready_heap, extract_heap, wfq_ready_heap ;
   
   static int heap_init(struct dn_heap *h, int size) ;
   static int heap_insert (struct dn_heap *h, dn_key key1, void *p);
   static void heap_extract(struct dn_heap *h, void *obj);
   
   static void transmit_event(struct dn_pipe *pipe);
   static void ready_event(struct dn_flow_queue *q);
   
   static struct dn_pipe *all_pipes = NULL ;       /* list of all pipes */
   static struct dn_flow_set *all_flow_sets = NULL ;/* list of all flow_sets */
   
   static struct callout dn_timeout;
   
   #ifdef SYSCTL_NODE
   SYSCTL_NODE(_net_inet_ip, OID_AUTO, dummynet,
                   CTLFLAG_RW, 0, "Dummynet");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, hash_size,
               CTLFLAG_RW, &dn_hash_size, 0, "Default hash table size");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, curr_time,
               CTLFLAG_RD, &curr_time, 0, "Current tick");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, ready_heap,
               CTLFLAG_RD, &ready_heap.size, 0, "Size of ready heap");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, extract_heap,
               CTLFLAG_RD, &extract_heap.size, 0, "Size of extract heap");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, searches,
               CTLFLAG_RD, &searches, 0, "Number of queue searches");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, search_steps,
               CTLFLAG_RD, &search_steps, 0, "Number of queue search steps");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, expire,
               CTLFLAG_RW, &pipe_expire, 0, "Expire queue if empty");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, max_chain_len,
               CTLFLAG_RW, &dn_max_ratio, 0,
           "Max ratio between dynamic queues and buckets");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, red_lookup_depth,
           CTLFLAG_RD, &red_lookup_depth, 0, "Depth of RED lookup table");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, red_avg_pkt_size,
           CTLFLAG_RD, &red_avg_pkt_size, 0, "RED Medium packet size");
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, red_max_pkt_size,
           CTLFLAG_RD, &red_max_pkt_size, 0, "RED Max packet size");
   #endif
   
   #ifdef DUMMYNET_DEBUG
   int     dummynet_debug = 0;
   #ifdef SYSCTL_NODE
   SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, debug, CTLFLAG_RW, &dummynet_debug,
               0, "control debugging printfs");
   #endif
   #define DPRINTF(X)      if (dummynet_debug) printf X
   #else
   #define DPRINTF(X)
   #endif
   
   static struct mtx dummynet_mtx;
   /*
    * NB: Recursion is needed to deal with re-entry via ICMP.  That is,
    *     a packet may be dispatched via ip_input from dummynet_io and
    *     re-enter through ip_output.  Yech.
    */
   #define DUMMYNET_LOCK_INIT() \
           mtx_init(&dummynet_mtx, "dummynet", NULL, MTX_DEF | MTX_RECURSE)
   #define DUMMYNET_LOCK_DESTROY() mtx_destroy(&dummynet_mtx)
   #define DUMMYNET_LOCK()         mtx_lock(&dummynet_mtx)
   #define DUMMYNET_UNLOCK()       mtx_unlock(&dummynet_mtx)
   #define DUMMYNET_LOCK_ASSERT()  mtx_assert(&dummynet_mtx, MA_OWNED)
   
   static int config_pipe(struct dn_pipe *p);
   static int ip_dn_ctl(struct sockopt *sopt);
   
   static void rt_unref(struct rtentry *, const char *);
   static void dummynet(void *);
   static void dummynet_flush(void);
   void dummynet_drain(void);
   static ip_dn_io_t dummynet_io;
   static void dn_rule_delete(void *);
   
   int if_tx_rdy(struct ifnet *ifp);
   
   static void
   rt_unref(struct rtentry *rt, const char *where)
   {
       if (rt == NULL)
           return ;
       RT_LOCK(rt);
       if (rt->rt_refcnt <= 0) {
           printf("dummynet: warning, refcnt now %ld, decreasing (%s)\n",
               rt->rt_refcnt, where);
       }
       RTFREE_LOCKED(rt);
   }
   
   /*
    * Heap management functions.
    *
    * In the heap, first node is element 0. Children of i are 2i+1 and 2i+2.
    * Some macros help finding parent/children so we can optimize them.
    *
    * heap_init() is called to expand the heap when needed.
    * Increment size in blocks of 16 entries.
    * XXX failure to allocate a new element is a pretty bad failure
    * as we basically stall a whole queue forever!!
    * Returns 1 on error, 0 on success
    */
   #define HEAP_FATHER(x) ( ( (x) - 1 ) / 2 )
   #define HEAP_LEFT(x) ( 2*(x) + 1 )
   #define HEAP_IS_LEFT(x) ( (x) & 1 )
   #define HEAP_RIGHT(x) ( 2*(x) + 2 )
   #define HEAP_SWAP(a, b, buffer) { buffer = a ; a = b ; b = buffer ; }
   #define HEAP_INCREMENT  15
   
   static int
   heap_init(struct dn_heap *h, int new_size)
   {
       struct dn_heap_entry *p;
   
       if (h->size >= new_size ) {
           printf("dummynet: %s, Bogus call, have %d want %d\n", __func__,
                   h->size, new_size);
           return 0 ;
       }
       new_size = (new_size + HEAP_INCREMENT ) & ~HEAP_INCREMENT ;
       p = malloc(new_size * sizeof(*p), M_DUMMYNET, M_NOWAIT);
       if (p == NULL) {
           printf("dummynet: %s, resize %d failed\n", __func__, new_size );
           return 1 ; /* error */
       }
       if (h->size > 0) {
           bcopy(h->p, p, h->size * sizeof(*p) );
           free(h->p, M_DUMMYNET);
       }
       h->p = p ;
       h->size = new_size ;
       return 0 ;
   }
   
   /*
    * Insert element in heap. Normally, p != NULL, we insert p in
    * a new position and bubble up. If p == NULL, then the element is
    * already in place, and key is the position where to start the
    * bubble-up.
    * Returns 1 on failure (cannot allocate new heap entry)
    *
    * If offset > 0 the position (index, int) of the element in the heap is
    * also stored in the element itself at the given offset in bytes.
    */
   #define SET_OFFSET(heap, node) \
       if (heap->offset > 0) \
               *((int *)((char *)(heap->p[node].object) + heap->offset)) = node ;
   /*
    * RESET_OFFSET is used for sanity checks. It sets offset to an invalid value.
    */
   #define RESET_OFFSET(heap, node) \
       if (heap->offset > 0) \
               *((int *)((char *)(heap->p[node].object) + heap->offset)) = -1 ;
   static int
   heap_insert(struct dn_heap *h, dn_key key1, void *p)
   {
       int son = h->elements ;
   
       if (p == NULL)      /* data already there, set starting point */
           son = key1 ;
       else {              /* insert new element at the end, possibly resize */
           son = h->elements ;
           if (son == h->size) /* need resize... */
               if (heap_init(h, h->elements+1) )
                   return 1 ; /* failure... */
           h->p[son].object = p ;
           h->p[son].key = key1 ;
           h->elements++ ;
       }
       while (son > 0) {                           /* bubble up */
           int father = HEAP_FATHER(son) ;
           struct dn_heap_entry tmp  ;
   
           if (DN_KEY_LT( h->p[father].key, h->p[son].key ) )
               break ; /* found right position */
           /* son smaller than father, swap and repeat */
           HEAP_SWAP(h->p[son], h->p[father], tmp) ;
           SET_OFFSET(h, son);
           son = father ;
       }
       SET_OFFSET(h, son);
       return 0 ;
   }
   
   /*
    * remove top element from heap, or obj if obj != NULL
    */
   static void
   heap_extract(struct dn_heap *h, void *obj)
   {
       int child, father, max = h->elements - 1 ;
   
       if (max < 0) {
           printf("dummynet: warning, extract from empty heap 0x%p\n", h);
           return ;
       }
       father = 0 ; /* default: move up smallest child */
       if (obj != NULL) { /* extract specific element, index is at offset */
           if (h->offset <= 0)
               panic("dummynet: heap_extract from middle not supported on this heap!!!\n");
           father = *((int *)((char *)obj + h->offset)) ;
           if (father < 0 || father >= h->elements) {
               printf("dummynet: heap_extract, father %d out of bound 0..%d\n",
                   father, h->elements);
               panic("dummynet: heap_extract");
           }
       }
       RESET_OFFSET(h, father);
       child = HEAP_LEFT(father) ;         /* left child */
       while (child <= max) {              /* valid entry */
           if (child != max && DN_KEY_LT(h->p[child+1].key, h->p[child].key) )
               child = child+1 ;           /* take right child, otherwise left */
           h->p[father] = h->p[child] ;
           SET_OFFSET(h, father);
           father = child ;
           child = HEAP_LEFT(child) ;   /* left child for next loop */
       }
       h->elements-- ;
       if (father != max) {
           /*
            * Fill hole with last entry and bubble up, reusing the insert code
            */
           h->p[father] = h->p[max] ;
           heap_insert(h, father, NULL); /* this one cannot fail */
       }
   }
   
   #if 0
   /*
    * change object position and update references
    * XXX this one is never used!
    */
   static void
   heap_move(struct dn_heap *h, dn_key new_key, void *object)
   {
       int temp;
       int i ;
       int max = h->elements-1 ;
       struct dn_heap_entry buf ;
   
       if (h->offset <= 0)
           panic("cannot move items on this heap");
   
       i = *((int *)((char *)object + h->offset));
       if (DN_KEY_LT(new_key, h->p[i].key) ) { /* must move up */
           h->p[i].key = new_key ;
           for (; i>0 && DN_KEY_LT(new_key, h->p[(temp = HEAP_FATHER(i))].key) ;
                    i = temp ) { /* bubble up */
               HEAP_SWAP(h->p[i], h->p[temp], buf) ;
               SET_OFFSET(h, i);
           }
       } else {            /* must move down */
           h->p[i].key = new_key ;
           while ( (temp = HEAP_LEFT(i)) <= max ) { /* found left child */
               if ((temp != max) && DN_KEY_GT(h->p[temp].key, h->p[temp+1].key))
                   temp++ ; /* select child with min key */
               if (DN_KEY_GT(new_key, h->p[temp].key)) { /* go down */
                   HEAP_SWAP(h->p[i], h->p[temp], buf) ;
                   SET_OFFSET(h, i);
               } else
                   break ;
               i = temp ;
           }
       }
       SET_OFFSET(h, i);
   }
   #endif /* heap_move, unused */
   
   /*
    * heapify() will reorganize data inside an array to maintain the
    * heap property. It is needed when we delete a bunch of entries.
    */
   static void
   heapify(struct dn_heap *h)
   {
       int i ;
   
       for (i = 0 ; i < h->elements ; i++ )
           heap_insert(h, i , NULL) ;
   }
   
   /*
    * cleanup the heap and free data structure
    */
   static void
   heap_free(struct dn_heap *h)
   {
       if (h->size >0 )
           free(h->p, M_DUMMYNET);
       bzero(h, sizeof(*h) );
   }
   
   /*
    * --- end of heap management functions ---
    */
   
   /*
    * Scheduler functions:
    *
    * transmit_event() is called when the delay-line needs to enter
    * the scheduler, either because of existing pkts getting ready,
    * or new packets entering the queue. The event handled is the delivery
    * time of the packet.
    *
    * ready_event() does something similar with fixed-rate queues, and the
    * event handled is the finish time of the head pkt.
    *
    * wfq_ready_event() does something similar with WF2Q queues, and the
    * event handled is the start time of the head pkt.
    *
    * In all cases, we make sure that the data structures are consistent
    * before passing pkts out, because this might trigger recursive
    * invocations of the procedures.
    */
   static void
   transmit_event(struct dn_pipe *pipe)
   {
       struct dn_pkt *pkt ;
   
       DUMMYNET_LOCK_ASSERT();
   
       while ( (pkt = pipe->head) && DN_KEY_LEQ(pkt->output_time, curr_time) ) {
           /*
            * first unlink, then call procedures, since ip_input() can invoke
            * ip_output() and viceversa, thus causing nested calls
            */
           pipe->head = DN_NEXT(pkt) ;
   
           /* XXX: drop the lock for now to avoid LOR's */
           DUMMYNET_UNLOCK();
           /*
            * The actual mbuf is preceded by a struct dn_pkt, resembling an mbuf
            * (NOT A REAL one, just a small block of malloc'ed memory) with
            *     m_type = MT_TAG, m_flags = PACKET_TAG_DUMMYNET
            *     dn_m (m_next) = actual mbuf to be processed by ip_input/output
            * and some other fields.
            * The block IS FREED HERE because it contains parameters passed
            * to the called routine.
            */
           switch (pkt->dn_dir) {
           case DN_TO_IP_OUT:
               (void)ip_output((struct mbuf *)pkt, NULL, NULL, 0, NULL, NULL);
               rt_unref (pkt->ro.ro_rt, __func__) ;
               break ;
   
           case DN_TO_IP_IN :
               ip_input((struct mbuf *)pkt) ;
               break ;
   
           case DN_TO_BDG_FWD :
               if (!BDG_LOADED) {
                   /* somebody unloaded the bridge module. Drop pkt */
                   /* XXX rate limit */
                   printf("dummynet: dropping bridged packet trapped in pipe\n");
                   m_freem(pkt->dn_m);
                   break;
               } /* fallthrough */
           case DN_TO_ETH_DEMUX:
               {
                   struct mbuf *m = (struct mbuf *)pkt ;
   
                   if (pkt->dn_m->m_len < ETHER_HDR_LEN &&
                       (pkt->dn_m = m_pullup(pkt->dn_m, ETHER_HDR_LEN)) == NULL) {
                       printf("dummynet/bridge: pullup fail, dropping pkt\n");
                       break;
                   }
                   /*
                    * bdg_forward() wants a pointer to the pseudo-mbuf-header, but
                    * on return it will supply the pointer to the actual packet
                    * (originally pkt->dn_m, but could be something else now) if
                    * it has not consumed it.
                    */
                   if (pkt->dn_dir == DN_TO_BDG_FWD) {
                       m = bdg_forward_ptr(m, pkt->ifp);
                       if (m)
                           m_freem(m);
                   } else
                       ether_demux(NULL, m); /* which consumes the mbuf */
               }
               break ;
           case DN_TO_ETH_OUT:
               ether_output_frame(pkt->ifp, (struct mbuf *)pkt);
               break;
   
           default:
               printf("dummynet: bad switch %d!\n", pkt->dn_dir);
               m_freem(pkt->dn_m);
               break ;
           }
           free(pkt, M_DUMMYNET);
           DUMMYNET_LOCK();
       }
       /* if there are leftover packets, put into the heap for next event */
       if ( (pkt = pipe->head) )
            heap_insert(&extract_heap, pkt->output_time, pipe ) ;
       /* XXX should check errors on heap_insert, by draining the
        * whole pipe p and hoping in the future we are more successful
        */
   }
   
   /*
    * the following macro computes how many ticks we have to wait
    * before being able to transmit a packet. The credit is taken from
    * either a pipe (WF2Q) or a flow_queue (per-flow queueing)
    */
   #define SET_TICKS(pkt, q, p)    \
       (pkt->dn_m->m_pkthdr.len*8*hz - (q)->numbytes + p->bandwidth - 1 ) / \
               p->bandwidth ;
   
   /*
    * extract pkt from queue, compute output time (could be now)
    * and put into delay line (p_queue)
    */
   static void
   move_pkt(struct dn_pkt *pkt, struct dn_flow_queue *q,
           struct dn_pipe *p, int len)
   {
       q->head = DN_NEXT(pkt) ;
       q->len-- ;
       q->len_bytes -= len ;
   
       pkt->output_time = curr_time + p->delay ;
   
       if (p->head == NULL)
           p->head = pkt;
       else
           DN_NEXT(p->tail) = pkt;
       p->tail = pkt;
       DN_NEXT(p->tail) = NULL;
   }
   
   /*
    * ready_event() is invoked every time the queue must enter the
    * scheduler, either because the first packet arrives, or because
    * a previously scheduled event fired.
    * On invokation, drain as many pkts as possible (could be 0) and then
    * if there are leftover packets reinsert the pkt in the scheduler.
    */
   static void
   ready_event(struct dn_flow_queue *q)
   {
       struct dn_pkt *pkt;
       struct dn_pipe *p = q->fs->pipe ;
       int p_was_empty ;
   
       DUMMYNET_LOCK_ASSERT();
   
       if (p == NULL) {
           printf("dummynet: ready_event- pipe is gone\n");
           return ;
       }
       p_was_empty = (p->head == NULL) ;
   
       /*
        * schedule fixed-rate queues linked to this pipe:
        * Account for the bw accumulated since last scheduling, then
        * drain as many pkts as allowed by q->numbytes and move to
        * the delay line (in p) computing output time.
        * bandwidth==0 (no limit) means we can drain the whole queue,
        * setting len_scaled = 0 does the job.
        */
       q->numbytes += ( curr_time - q->sched_time ) * p->bandwidth;
       while ( (pkt = q->head) != NULL ) {
           int len = pkt->dn_m->m_pkthdr.len;
           int len_scaled = p->bandwidth ? len*8*hz : 0 ;
           if (len_scaled > q->numbytes )
               break ;
           q->numbytes -= len_scaled ;
           move_pkt(pkt, q, p, len);
       }
       /*
        * If we have more packets queued, schedule next ready event
        * (can only occur when bandwidth != 0, otherwise we would have
        * flushed the whole queue in the previous loop).
        * To this purpose we record the current time and compute how many
        * ticks to go for the finish time of the packet.
        */
       if ( (pkt = q->head) != NULL ) { /* this implies bandwidth != 0 */
           dn_key t = SET_TICKS(pkt, q, p); /* ticks i have to wait */
           q->sched_time = curr_time ;
           heap_insert(&ready_heap, curr_time + t, (void *)q );
           /* XXX should check errors on heap_insert, and drain the whole
            * queue on error hoping next time we are luckier.
            */
       } else {    /* RED needs to know when the queue becomes empty */
           q->q_time = curr_time;
           q->numbytes = 0;
       }
       /*
        * If the delay line was empty call transmit_event(p) now.
        * Otherwise, the scheduler will take care of it.
        */
       if (p_was_empty)
           transmit_event(p);
   }
   
   /*
    * Called when we can transmit packets on WF2Q queues. Take pkts out of
    * the queues at their start time, and enqueue into the delay line.
    * Packets are drained until p->numbytes < 0. As long as
    * len_scaled >= p->numbytes, the packet goes into the delay line
    * with a deadline p->delay. For the last packet, if p->numbytes<0,
    * there is an additional delay.
    */
   static void
   ready_event_wfq(struct dn_pipe *p)
   {
       int p_was_empty = (p->head == NULL) ;
       struct dn_heap *sch = &(p->scheduler_heap);
       struct dn_heap *neh = &(p->not_eligible_heap) ;
   
       DUMMYNET_LOCK_ASSERT();
   
       if (p->if_name[0] == 0) /* tx clock is simulated */
           p->numbytes += ( curr_time - p->sched_time ) * p->bandwidth;
       else { /* tx clock is for real, the ifq must be empty or this is a NOP */
           if (p->ifp && p->ifp->if_snd.ifq_head != NULL)
               return ;
           else {
               DPRINTF(("dummynet: pipe %d ready from %s --\n",
                   p->pipe_nr, p->if_name));
           }
       }
   
       /*
        * While we have backlogged traffic AND credit, we need to do
        * something on the queue.
        */
       while ( p->numbytes >=0 && (sch->elements>0 || neh->elements >0) ) {
           if (sch->elements > 0) { /* have some eligible pkts to send out */
               struct dn_flow_queue *q = sch->p[0].object ;
               struct dn_pkt *pkt = q->head;
               struct dn_flow_set *fs = q->fs;
               u_int64_t len = pkt->dn_m->m_pkthdr.len;
               int len_scaled = p->bandwidth ? len*8*hz : 0 ;
   
               heap_extract(sch, NULL); /* remove queue from heap */
               p->numbytes -= len_scaled ;
               move_pkt(pkt, q, p, len);
   
               p->V += (len<<MY_M) / p->sum ; /* update V */
               q->S = q->F ; /* update start time */
               if (q->len == 0) { /* Flow not backlogged any more */
                   fs->backlogged-- ;
                   heap_insert(&(p->idle_heap), q->F, q);
               } else { /* still backlogged */
                   /*
                    * update F and position in backlogged queue, then
                    * put flow in not_eligible_heap (we will fix this later).
                    */
                   len = (q->head)->dn_m->m_pkthdr.len;
                   q->F += (len<<MY_M)/(u_int64_t) fs->weight ;
                   if (DN_KEY_LEQ(q->S, p->V))
                       heap_insert(neh, q->S, q);
                   else
                       heap_insert(sch, q->F, q);
               }
           }
           /*
            * now compute V = max(V, min(S_i)). Remember that all elements in sch
            * have by definition S_i <= V so if sch is not empty, V is surely
            * the max and we must not update it. Conversely, if sch is empty
            * we only need to look at neh.
            */
           if (sch->elements == 0 && neh->elements > 0)
               p->V = MAX64 ( p->V, neh->p[0].key );
           /* move from neh to sch any packets that have become eligible */
           while (neh->elements > 0 && DN_KEY_LEQ(neh->p[0].key, p->V) ) {
               struct dn_flow_queue *q = neh->p[0].object ;
               heap_extract(neh, NULL);
               heap_insert(sch, q->F, q);
           }
   
           if (p->if_name[0] != '\0') {/* tx clock is from a real thing */
               p->numbytes = -1 ; /* mark not ready for I/O */
               break ;
           }
       }
       if (sch->elements == 0 && neh->elements == 0 && p->numbytes >= 0
               && p->idle_heap.elements > 0) {
           /*
            * no traffic and no events scheduled. We can get rid of idle-heap.
            */
           int i ;
   
           for (i = 0 ; i < p->idle_heap.elements ; i++) {
               struct dn_flow_queue *q = p->idle_heap.p[i].object ;
   
               q->F = 0 ;
               q->S = q->F + 1 ;
           }
           p->sum = 0 ;
           p->V = 0 ;
           p->idle_heap.elements = 0 ;
       }
       /*
        * If we are getting clocks from dummynet (not a real interface) and
        * If we are under credit, schedule the next ready event.
        * Also fix the delivery time of the last packet.
        */
       if (p->if_name[0]==0 && p->numbytes < 0) { /* this implies bandwidth >0 */
           dn_key t=0 ; /* number of ticks i have to wait */
   
           if (p->bandwidth > 0)
               t = ( p->bandwidth -1 - p->numbytes) / p->bandwidth ;
           p->tail->output_time += t ;
           p->sched_time = curr_time ;
           heap_insert(&wfq_ready_heap, curr_time + t, (void *)p);
           /* XXX should check errors on heap_insert, and drain the whole
            * queue on error hoping next time we are luckier.
            */
       }
       /*
        * If the delay line was empty call transmit_event(p) now.
        * Otherwise, the scheduler will take care of it.
        */
       if (p_was_empty)
           transmit_event(p);
   }
   
   /*
    * This is called once per tick, or HZ times per second. It is used to
    * increment the current tick counter and schedule expired events.
    */
   static void
   dummynet(void * __unused unused)
   {
       void *p ; /* generic parameter to handler */
       struct dn_heap *h ;
       struct dn_heap *heaps[3];
       int i;
       struct dn_pipe *pe ;
   
       heaps[0] = &ready_heap ;            /* fixed-rate queues */
       heaps[1] = &wfq_ready_heap ;        /* wfq queues */
       heaps[2] = &extract_heap ;          /* delay line */
   
       DUMMYNET_LOCK();
       curr_time++ ;
       for (i=0; i < 3 ; i++) {
           h = heaps[i];
           while (h->elements > 0 && DN_KEY_LEQ(h->p[0].key, curr_time) ) {
               if (h->p[0].key > curr_time)
                   printf("dummynet: warning, heap %d is %d ticks late\n",
                       i, (int)(curr_time - h->p[0].key));
               p = h->p[0].object ; /* store a copy before heap_extract */
               heap_extract(h, NULL); /* need to extract before processing */
               if (i == 0)
                   ready_event(p) ;
               else if (i == 1) {
                   struct dn_pipe *pipe = p;
                   if (pipe->if_name[0] != '\0')
                       printf("dummynet: bad ready_event_wfq for pipe %s\n",
                           pipe->if_name);
                   else
                       ready_event_wfq(p) ;
               } else
                   transmit_event(p);
           }
       }
       /* sweep pipes trying to expire idle flow_queues */
       for (pe = all_pipes; pe ; pe = pe->next )
           if (pe->idle_heap.elements > 0 &&
                   DN_KEY_LT(pe->idle_heap.p[0].key, pe->V) ) {
               struct dn_flow_queue *q = pe->idle_heap.p[0].object ;
   
               heap_extract(&(pe->idle_heap), NULL);
               q->S = q->F + 1 ; /* mark timestamp as invalid */
               pe->sum -= q->fs->weight ;
           }
       DUMMYNET_UNLOCK();
   
       callout_reset(&dn_timeout, 1, dummynet, NULL);
   }
   
   /*
    * called by an interface when tx_rdy occurs.
    */
   int
   if_tx_rdy(struct ifnet *ifp)
   {
       struct dn_pipe *p;
   
       DUMMYNET_LOCK();
       for (p = all_pipes; p ; p = p->next )
           if (p->ifp == ifp)
               break ;
       if (p == NULL) {
           for (p = all_pipes; p ; p = p->next )
               if (!strcmp(p->if_name, ifp->if_xname) ) {
                   p->ifp = ifp ;
                   DPRINTF(("dummynet: ++ tx rdy from %s (now found)\n",
                           ifp->if_xname));
                   break ;
               }
       }
       if (p != NULL) {
           DPRINTF(("dummynet: ++ tx rdy from %s - qlen %d\n", ifp->if_xname,
                   ifp->if_snd.ifq_len));
           p->numbytes = 0 ; /* mark ready for I/O */
           ready_event_wfq(p);
       }
       DUMMYNET_UNLOCK();
   
       return 0;
   }
   
   /*
    * Unconditionally expire empty queues in case of shortage.
    * Returns the number of queues freed.
    */
   static int
   expire_queues(struct dn_flow_set *fs)
   {
       struct dn_flow_queue *q, *prev ;
       int i, initial_elements = fs->rq_elements ;
   
       if (fs->last_expired == time_second)
           return 0 ;
       fs->last_expired = time_second ;
       for (i = 0 ; i <= fs->rq_size ; i++) /* last one is overflow */
           for (prev=NULL, q = fs->rq[i] ; q != NULL ; )
               if (q->head != NULL || q->S != q->F+1) {
                   prev = q ;
                   q = q->next ;
               } else { /* entry is idle, expire it */
                   struct dn_flow_queue *old_q = q ;
   
                   if (prev != NULL)
                       prev->next = q = q->next ;
                   else
                       fs->rq[i] = q = q->next ;
                   fs->rq_elements-- ;
                   free(old_q, M_DUMMYNET);
               }
       return initial_elements - fs->rq_elements ;
   }
   
   /*
    * If room, create a new queue and put at head of slot i;
    * otherwise, create or use the default queue.
    */
   static struct dn_flow_queue *
   create_queue(struct dn_flow_set *fs, int i)
   {
       struct dn_flow_queue *q ;
   
       if (fs->rq_elements > fs->rq_size * dn_max_ratio &&
               expire_queues(fs) == 0) {
           /*
            * No way to get room, use or create overflow queue.
            */
           i = fs->rq_size ;
           if ( fs->rq[i] != NULL )
               return fs->rq[i] ;
       }
       q = malloc(sizeof(*q), M_DUMMYNET, M_NOWAIT | M_ZERO);
       if (q == NULL) {
           printf("dummynet: sorry, cannot allocate queue for new flow\n");
           return NULL ;
       }
       q->fs = fs ;
       q->hash_slot = i ;
       q->next = fs->rq[i] ;
       q->S = q->F + 1;   /* hack - mark timestamp as invalid */
       fs->rq[i] = q ;
       fs->rq_elements++ ;
       return q ;
   }
   
   /*
    * Given a flow_set and a pkt in last_pkt, find a matching queue
    * after appropriate masking. The queue is moved to front
    * so that further searches take less time.
    */
   static struct dn_flow_queue *
   find_queue(struct dn_flow_set *fs, struct ipfw_flow_id *id)
   {
       int i = 0 ; /* we need i and q for new allocations */
       struct dn_flow_queue *q, *prev;
   
       if ( !(fs->flags_fs & DN_HAVE_FLOW_MASK) )
           q = fs->rq[0] ;
       else {
           /* first, do the masking */
           id->dst_ip &= fs->flow_mask.dst_ip ;
           id->src_ip &= fs->flow_mask.src_ip ;
           id->dst_port &= fs->flow_mask.dst_port ;
           id->src_port &= fs->flow_mask.src_port ;
           id->proto &= fs->flow_mask.proto ;
           id->flags = 0 ; /* we don't care about this one */
           /* then, hash function */
           i = ( (id->dst_ip) & 0xffff ) ^
               ( (id->dst_ip >> 15) & 0xffff ) ^
               ( (id->src_ip << 1) & 0xffff ) ^
               ( (id->src_ip >> 16 ) & 0xffff ) ^
               (id->dst_port << 1) ^ (id->src_port) ^
               (id->proto );
           i = i % fs->rq_size ;
           /* finally, scan the current list for a match */
           searches++ ;
           for (prev=NULL, q = fs->rq[i] ; q ; ) {
               search_steps++;
               if (id->dst_ip == q->id.dst_ip &&
                       id->src_ip == q->id.src_ip &&
                       id->dst_port == q->id.dst_port &&
                       id->src_port == q->id.src_port &&
                       id->proto == q->id.proto &&
                       id->flags == q->id.flags)
                   break ; /* found */
               else if (pipe_expire && q->head == NULL && q->S == q->F+1 ) {
                   /* entry is idle and not in any heap, expire it */
                   struct dn_flow_queue *old_q = q ;
   
                   if (prev != NULL)
                       prev->next = q = q->next ;
                   else
                       fs->rq[i] = q = q->next ;
                   fs->rq_elements-- ;
                   free(old_q, M_DUMMYNET);
                   continue ;
               }
               prev = q ;
               q = q->next ;
           }
           if (q && prev != NULL) { /* found and not in front */
               prev->next = q->next ;
               q->next = fs->rq[i] ;
               fs->rq[i] = q ;
           }
       }
       if (q == NULL) { /* no match, need to allocate a new entry */
           q = create_queue(fs, i);
           if (q != NULL)
           q->id = *id ;
       }
       return q ;
   }
   
   static int
   red_drops(struct dn_flow_set *fs, struct dn_flow_queue *q, int len)
   {
       /*
        * RED algorithm
        *
        * RED calculates the average queue size (avg) using a low-pass filter
        * with an exponential weighted (w_q) moving average:
        *  avg  <-  (1-w_q) * avg + w_q * q_size
        * where q_size is the queue length (measured in bytes or * packets).
        *
        * If q_size == 0, we compute the idle time for the link, and set
        *  avg = (1 - w_q)^(idle/s)
        * where s is the time needed for transmitting a medium-sized packet.
        *
        * Now, if avg < min_th the packet is enqueued.
        * If avg > max_th the packet is dropped. Otherwise, the packet is
        * dropped with probability P function of avg.
        *
        */
   
       int64_t p_b = 0;
       /* queue in bytes or packets ? */
       u_int q_size = (fs->flags_fs & DN_QSIZE_IS_BYTES) ? q->len_bytes : q->len;
   
       DPRINTF(("\ndummynet: %d q: %2u ", (int) curr_time, q_size));
   
       /* average queue size estimation */
       if (q_size != 0) {
           /*
            * queue is not empty, avg <- avg + (q_size - avg) * w_q
            */
           int diff = SCALE(q_size) - q->avg;
           int64_t v = SCALE_MUL((int64_t) diff, (int64_t) fs->w_q);
   
           q->avg += (int) v;
       } else {
           /*
            * queue is empty, find for how long the queue has been
            * empty and use a lookup table for computing
            * (1 - * w_q)^(idle_time/s) where s is the time to send a
            * (small) packet.
            * XXX check wraps...
            */
           if (q->avg) {
               u_int t = (curr_time - q->q_time) / fs->lookup_step;
   
               q->avg = (t < fs->lookup_depth) ?
                       SCALE_MUL(q->avg, fs->w_q_lookup[t]) : 0;
           }
      }
      DPRINTF(("dummynet: avg: %u ", SCALE_VAL(q->avg)));
  
      /* should i drop ? */
  
      if (q->avg < fs->min_th) {
          q->count = -1;
          return 0; /* accept packet ; */
      }
      if (q->avg >= fs->max_th) { /* average queue >=  max threshold */
          if (fs->flags_fs & DN_IS_GENTLE_RED) {
              /*
               * According to Gentle-RED, if avg is greater than max_th the
               * packet is dropped with a probability
               *  p_b = c_3 * avg - c_4
               * where c_3 = (1 - max_p) / max_th, and c_4 = 1 - 2 * max_p
               */
              p_b = SCALE_MUL((int64_t) fs->c_3, (int64_t) q->avg) - fs->c_4;
          } else {
              q->count = -1;
              DPRINTF(("dummynet: - drop"));
              return 1 ;
          }
      } else if (q->avg > fs->min_th) {
          /*
           * we compute p_b using the linear dropping function p_b = c_1 *
           * avg - c_2, where c_1 = max_p / (max_th - min_th), and c_2 =
           * max_p * min_th / (max_th - min_th)
           */
          p_b = SCALE_MUL((int64_t) fs->c_1, (int64_t) q->avg) - fs->c_2;
      }
      if (fs->flags_fs & DN_QSIZE_IS_BYTES)
          p_b = (p_b * len) / fs->max_pkt_size;
      if (++q->count == 0)
          q->random = random() & 0xffff;
      else {
          /*
           * q->count counts packets arrived since last drop, so a greater
           * value of q->count means a greater packet drop probability.
           */
          if (SCALE_MUL(p_b, SCALE((int64_t) q->count)) > q->random) {
              q->count = 0;
              DPRINTF(("dummynet: - red drop"));
              /* after a drop we calculate a new random value */
              q->random = random() & 0xffff;
              return 1;    /* drop */
          }
      }
      /* end of RED algorithm */
      return 0 ; /* accept */
  }
  
  static __inline
  struct dn_flow_set *
  locate_flowset(int pipe_nr, struct ip_fw *rule)
  {
  #if IPFW2
      struct dn_flow_set *fs;
      ipfw_insn *cmd = rule->cmd + rule->act_ofs;
  
      if (cmd->opcode == O_LOG)
          cmd += F_LEN(cmd);
  #ifdef __i386__
      fs = ((ipfw_insn_pipe *)cmd)->pipe_ptr;
  #else
      bcopy(& ((ipfw_insn_pipe *)cmd)->pipe_ptr, &fs, sizeof(fs));
  #endif
  
      if (fs != NULL)
          return fs;
  
      if (cmd->opcode == O_QUEUE)
  #else /* !IPFW2 */
      struct dn_flow_set *fs = NULL ;
  
      if ( (rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_QUEUE )
  #endif /* !IPFW2 */
          for (fs=all_flow_sets; fs && fs->fs_nr != pipe_nr; fs=fs->next)
              ;
      else {
          struct dn_pipe *p1;
          for (p1 = all_pipes; p1 && p1->pipe_nr != pipe_nr; p1 = p1->next)
              ;
          if (p1 != NULL)
              fs = &(p1->fs) ;
      }
      /* record for the future */
  #if IPFW2
  #ifdef __i386__
      ((ipfw_insn_pipe *)cmd)->pipe_ptr = fs;
  #else
      bcopy(&fs, & ((ipfw_insn_pipe *)cmd)->pipe_ptr, sizeof(fs));
  #endif
  #else
      if (fs != NULL)
          rule->pipe_ptr = fs;
  #endif
      return fs ;
  }
  
  /*
   * dummynet hook for packets. Below 'pipe' is a pipe or a queue
   * depending on whether WF2Q or fixed bw is used.
   *
   * pipe_nr      pipe or queue the packet is destined for.
   * dir          where shall we send the packet after dummynet.
   * m            the mbuf with the packet
   * ifp          the 'ifp' parameter from the caller.
   *              NULL in ip_input, destination interface in ip_output,
   *              real_dst in bdg_forward
   * ro           route parameter (only used in ip_output, NULL otherwise)
   * dst          destination address, only used by ip_output
   * rule         matching rule, in case of multiple passes
   * flags        flags from the caller, only used in ip_output
   *
   */
  static int
  dummynet_io(struct mbuf *m, int pipe_nr, int dir, struct ip_fw_args *fwa)
  {
      struct dn_pkt *pkt;
      struct dn_flow_set *fs;
      struct dn_pipe *pipe ;
      u_int64_t len = m->m_pkthdr.len ;
      struct dn_flow_queue *q = NULL ;
      int is_pipe;
  #if IPFW2
      ipfw_insn *cmd = fwa->rule->cmd + fwa->rule->act_ofs;
  
      if (cmd->opcode == O_LOG)
          cmd += F_LEN(cmd);
      is_pipe = (cmd->opcode == O_PIPE);
  #else
      is_pipe = (fwa->rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_PIPE;
  #endif
  
      pipe_nr &= 0xffff ;
  
      DUMMYNET_LOCK();
      /*
       * This is a dummynet rule, so we expect an O_PIPE or O_QUEUE rule.
       */
      fs = locate_flowset(pipe_nr, fwa->rule);
      if (fs == NULL)
          goto dropit ;   /* this queue/pipe does not exist! */
      pipe = fs->pipe ;
      if (pipe == NULL) { /* must be a queue, try find a matching pipe */
          for (pipe = all_pipes; pipe && pipe->pipe_nr != fs->parent_nr;
                   pipe = pipe->next)
              ;
          if (pipe != NULL)
              fs->pipe = pipe ;
          else {
              printf("dummynet: no pipe %d for queue %d, drop pkt\n",
                  fs->parent_nr, fs->fs_nr);
              goto dropit ;
          }
      }
      q = find_queue(fs, &(fwa->f_id));
      if ( q == NULL )
          goto dropit ;           /* cannot allocate queue                */
      /*
       * update statistics, then check reasons to drop pkt
       */
      q->tot_bytes += len ;
      q->tot_pkts++ ;
      if ( fs->plr && random() < fs->plr )
          goto dropit ;           /* random pkt drop                      */
      if ( fs->flags_fs & DN_QSIZE_IS_BYTES) {
          if (q->len_bytes > fs->qsize)
              goto dropit ;       /* queue size overflow                  */
      } else {
          if (q->len >= fs->qsize)
              goto dropit ;       /* queue count overflow                 */
      }
      if ( fs->flags_fs & DN_IS_RED && red_drops(fs, q, len) )
          goto dropit ;
  
      /* XXX expensive to zero, see if we can remove it*/
      pkt = (struct dn_pkt *)malloc(sizeof (*pkt), M_DUMMYNET, M_NOWAIT|M_ZERO);
      if ( pkt == NULL )
          goto dropit ;           /* cannot allocate packet header        */
      /* ok, i can handle the pkt now... */
      /* build and enqueue packet + parameters */
      pkt->hdr.mh_type = MT_TAG;
      pkt->hdr.mh_flags = PACKET_TAG_DUMMYNET;
      pkt->rule = fwa->rule ;
      DN_NEXT(pkt) = NULL;
      pkt->dn_m = m;
      pkt->dn_dir = dir ;
  
      pkt->ifp = fwa->oif;
      if (dir == DN_TO_IP_OUT) {
          /*
           * We need to copy *ro because for ICMP pkts (and maybe others)
           * the caller passed a pointer into the stack; dst might also be
           * a pointer into *ro so it needs to be updated.
           */
          pkt->ro = *(fwa->ro);
          if (pkt->ro.ro_rt) {
              RT_LOCK(pkt->ro.ro_rt);
              RT_ADDREF(pkt->ro.ro_rt) ;
              RT_UNLOCK(pkt->ro.ro_rt);
          }
          if (fwa->dst == (struct sockaddr_in *)&fwa->ro->ro_dst) /* dst points into ro */
              fwa->dst = (struct sockaddr_in *)&(pkt->ro.ro_dst) ;
          pkt->dn_dst = fwa->dst;
          pkt->flags = fwa->flags;
      }
      if (q->head == NULL)
          q->head = pkt;
      else
          DN_NEXT(q->tail) = pkt;
      q->tail = pkt;
      q->len++;
      q->len_bytes += len ;
  
      if ( q->head != pkt )       /* flow was not idle, we are done */
          goto done;
      /*
       * If we reach this point the flow was previously idle, so we need
       * to schedule it. This involves different actions for fixed-rate or
       * WF2Q queues.
       */
      if (is_pipe) {
          /*
           * Fixed-rate queue: just insert into the ready_heap.
           */
          dn_key t = 0 ;
          if (pipe->bandwidth)
              t = SET_TICKS(pkt, q, pipe);
          q->sched_time = curr_time ;
          if (t == 0)     /* must process it now */
              ready_event( q );
          else
              heap_insert(&ready_heap, curr_time + t , q );
      } else {
          /*
           * WF2Q. First, compute start time S: if the flow was idle (S=F+1)
           * set S to the virtual time V for the controlling pipe, and update
           * the sum of weights for the pipe; otherwise, remove flow from
           * idle_heap and set S to max(F,V).
           * Second, compute finish time F = S + len/weight.
           * Third, if pipe was idle, update V=max(S, V).
           * Fourth, count one more backlogged flow.
           */
          if (DN_KEY_GT(q->S, q->F)) { /* means timestamps are invalid */
              q->S = pipe->V ;
              pipe->sum += fs->weight ; /* add weight of new queue */
          } else {
              heap_extract(&(pipe->idle_heap), q);
              q->S = MAX64(q->F, pipe->V ) ;
          }
          q->F = q->S + ( len<<MY_M )/(u_int64_t) fs->weight;
  
          if (pipe->not_eligible_heap.elements == 0 &&
                  pipe->scheduler_heap.elements == 0)
              pipe->V = MAX64 ( q->S, pipe->V );
          fs->backlogged++ ;
          /*
           * Look at eligibility. A flow is not eligibile if S>V (when
           * this happens, it means that there is some other flow already
           * scheduled for the same pipe, so the scheduler_heap cannot be
           * empty). If the flow is not eligible we just store it in the
           * not_eligible_heap. Otherwise, we store in the scheduler_heap
           * and possibly invoke ready_event_wfq() right now if there is
           * leftover credit.
           * Note that for all flows in scheduler_heap (SCH), S_i <= V,
           * and for all flows in not_eligible_heap (NEH), S_i > V .
           * So when we need to compute max( V, min(S_i) ) forall i in SCH+NEH,
           * we only need to look into NEH.
           */
          if (DN_KEY_GT(q->S, pipe->V) ) { /* not eligible */
              if (pipe->scheduler_heap.elements == 0)
                  printf("dummynet: ++ ouch! not eligible but empty scheduler!\n");
              heap_insert(&(pipe->not_eligible_heap), q->S, q);
          } else {
              heap_insert(&(pipe->scheduler_heap), q->F, q);
              if (pipe->numbytes >= 0) { /* pipe is idle */
                  if (pipe->scheduler_heap.elements != 1)
                      printf("dummynet: OUCH! pipe should have been idle!\n");
                  DPRINTF(("dummynet: waking up pipe %d at %d\n",
                          pipe->pipe_nr, (int)(q->F >> MY_M)));
                  pipe->sched_time = curr_time ;
                  ready_event_wfq(pipe);
              }
          }
      }
  done:
      DUMMYNET_UNLOCK();
      return 0;
  
  dropit:
      if (q)
          q->drops++ ;
      DUMMYNET_UNLOCK();
      m_freem(m);
      return ( (fs && (fs->flags_fs & DN_NOERROR)) ? 0 : ENOBUFS);
  }
  
  /*
   * Below, the rt_unref is only needed when (pkt->dn_dir == DN_TO_IP_OUT)
   * Doing this would probably save us the initial bzero of dn_pkt
   */
  #define DN_FREE_PKT(pkt)        {               \
          struct dn_pkt *n = pkt ;                \
          rt_unref ( n->ro.ro_rt, __func__ ) ;    \
          m_freem(n->dn_m);                       \
          pkt = DN_NEXT(n) ;                      \
          free(n, M_DUMMYNET) ;   }
  
  /*
   * Dispose all packets and flow_queues on a flow_set.
   * If all=1, also remove red lookup table and other storage,
   * including the descriptor itself.
   * For the one in dn_pipe MUST also cleanup ready_heap...
   */
  static void
  purge_flow_set(struct dn_flow_set *fs, int all)
  {
      struct dn_pkt *pkt ;
      struct dn_flow_queue *q, *qn ;
      int i ;
  
      DUMMYNET_LOCK_ASSERT();
  
      for (i = 0 ; i <= fs->rq_size ; i++ ) {
          for (q = fs->rq[i] ; q ; q = qn ) {
              for (pkt = q->head ; pkt ; )
                  DN_FREE_PKT(pkt) ;
              qn = q->next ;
              free(q, M_DUMMYNET);
          }
          fs->rq[i] = NULL ;
      }
      fs->rq_elements = 0 ;
      if (all) {
          /* RED - free lookup table */
          if (fs->w_q_lookup)
              free(fs->w_q_lookup, M_DUMMYNET);
          if (fs->rq)
              free(fs->rq, M_DUMMYNET);
          /* if this fs is not part of a pipe, free it */
          if (fs->pipe && fs != &(fs->pipe->fs) )
              free(fs, M_DUMMYNET);
      }
  }
  
  /*
   * Dispose all packets queued on a pipe (not a flow_set).
   * Also free all resources associated to a pipe, which is about
   * to be deleted.
   */
  static void
  purge_pipe(struct dn_pipe *pipe)
  {
      struct dn_pkt *pkt ;
  
      purge_flow_set( &(pipe->fs), 1 );
  
      for (pkt = pipe->head ; pkt ; )
          DN_FREE_PKT(pkt) ;
  
      heap_free( &(pipe->scheduler_heap) );
      heap_free( &(pipe->not_eligible_heap) );
      heap_free( &(pipe->idle_heap) );
  }
  
  /*
   * Delete all pipes and heaps returning memory. Must also
   * remove references from all ipfw rules to all pipes.
   */
  static void
  dummynet_flush()
  {
      struct dn_pipe *curr_p, *p ;
      struct dn_flow_set *fs, *curr_fs;
  
      DUMMYNET_LOCK();
      /* remove all references to pipes ...*/
      flush_pipe_ptrs(NULL);
      /* prevent future matches... */
      p = all_pipes ;
      all_pipes = NULL ;
      fs = all_flow_sets ;
      all_flow_sets = NULL ;
      /* and free heaps so we don't have unwanted events */
      heap_free(&ready_heap);
      heap_free(&wfq_ready_heap);
      heap_free(&extract_heap);
  
      /*
       * Now purge all queued pkts and delete all pipes
       */
      /* scan and purge all flow_sets. */
      for ( ; fs ; ) {
          curr_fs = fs ;
          fs = fs->next ;
          purge_flow_set(curr_fs, 1);
      }
      for ( ; p ; ) {
          purge_pipe(p);
          curr_p = p ;
          p = p->next ;
          free(curr_p, M_DUMMYNET);
      }
      DUMMYNET_UNLOCK();
  }
  
  
  extern struct ip_fw *ip_fw_default_rule ;
  static void
  dn_rule_delete_fs(struct dn_flow_set *fs, void *r)
  {
      int i ;
      struct dn_flow_queue *q ;
      struct dn_pkt *pkt ;
  
      for (i = 0 ; i <= fs->rq_size ; i++) /* last one is ovflow */
          for (q = fs->rq[i] ; q ; q = q->next )
              for (pkt = q->head ; pkt ; pkt = DN_NEXT(pkt) )
                  if (pkt->rule == r)
                      pkt->rule = ip_fw_default_rule ;
  }
  /*
   * when a firewall rule is deleted, scan all queues and remove the flow-id
   * from packets matching this rule.
   */
  void
  dn_rule_delete(void *r)
  {
      struct dn_pipe *p ;
      struct dn_pkt *pkt ;
      struct dn_flow_set *fs ;
  
      DUMMYNET_LOCK();
      /*
       * If the rule references a queue (dn_flow_set), then scan
       * the flow set, otherwise scan pipes. Should do either, but doing
       * both does not harm.
       */
      for ( fs = all_flow_sets ; fs ; fs = fs->next )
          dn_rule_delete_fs(fs, r);
      for ( p = all_pipes ; p ; p = p->next ) {
          fs = &(p->fs) ;
          dn_rule_delete_fs(fs, r);
          for (pkt = p->head ; pkt ; pkt = DN_NEXT(pkt) )
              if (pkt->rule == r)
                  pkt->rule = ip_fw_default_rule ;
      }
      DUMMYNET_UNLOCK();
  }
  
  /*
   * setup RED parameters
   */
  static int
  config_red(struct dn_flow_set *p, struct dn_flow_set * x)
  {
      int i;
  
      x->w_q = p->w_q;
      x->min_th = SCALE(p->min_th);
      x->max_th = SCALE(p->max_th);
      x->max_p = p->max_p;
  
      x->c_1 = p->max_p / (p->max_th - p->min_th);
      x->c_2 = SCALE_MUL(x->c_1, SCALE(p->min_th));
      if (x->flags_fs & DN_IS_GENTLE_RED) {
          x->c_3 = (SCALE(1) - p->max_p) / p->max_th;
          x->c_4 = (SCALE(1) - 2 * p->max_p);
      }
  
      /* if the lookup table already exist, free and create it again */
      if (x->w_q_lookup) {
          free(x->w_q_lookup, M_DUMMYNET);
          x->w_q_lookup = NULL ;
      }
      if (red_lookup_depth == 0) {
          printf("\ndummynet: net.inet.ip.dummynet.red_lookup_depth must be > 0\n");
          free(x, M_DUMMYNET);
          return EINVAL;
      }
      x->lookup_depth = red_lookup_depth;
      x->w_q_lookup = (u_int *) malloc(x->lookup_depth * sizeof(int),
              M_DUMMYNET, M_NOWAIT);
      if (x->w_q_lookup == NULL) {
          printf("dummynet: sorry, cannot allocate red lookup table\n");
          free(x, M_DUMMYNET);
          return ENOSPC;
      }
  
      /* fill the lookup table with (1 - w_q)^x */
      x->lookup_step = p->lookup_step ;
      x->lookup_weight = p->lookup_weight ;
      x->w_q_lookup[0] = SCALE(1) - x->w_q;
      for (i = 1; i < x->lookup_depth; i++)
          x->w_q_lookup[i] = SCALE_MUL(x->w_q_lookup[i - 1], x->lookup_weight);
      if (red_avg_pkt_size < 1)
          red_avg_pkt_size = 512 ;
      x->avg_pkt_size = red_avg_pkt_size ;
      if (red_max_pkt_size < 1)
          red_max_pkt_size = 1500 ;
      x->max_pkt_size = red_max_pkt_size ;
      return 0 ;
  }
  
  static int
  alloc_hash(struct dn_flow_set *x, struct dn_flow_set *pfs)
  {
      if (x->flags_fs & DN_HAVE_FLOW_MASK) {     /* allocate some slots */
          int l = pfs->rq_size;
  
          if (l == 0)
              l = dn_hash_size;
          if (l < 4)
              l = 4;
          else if (l > DN_MAX_HASH_SIZE)
              l = DN_MAX_HASH_SIZE;
          x->rq_size = l;
      } else                  /* one is enough for null mask */
          x->rq_size = 1;
      x->rq = malloc((1 + x->rq_size) * sizeof(struct dn_flow_queue *),
              M_DUMMYNET, M_NOWAIT | M_ZERO);
      if (x->rq == NULL) {
          printf("dummynet: sorry, cannot allocate queue\n");
          return ENOSPC;
      }
      x->rq_elements = 0;
      return 0 ;
  }
  
  static void
  set_fs_parms(struct dn_flow_set *x, struct dn_flow_set *src)
  {
      x->flags_fs = src->flags_fs;
      x->qsize = src->qsize;
      x->plr = src->plr;
      x->flow_mask = src->flow_mask;
      if (x->flags_fs & DN_QSIZE_IS_BYTES) {
          if (x->qsize > 1024*1024)
              x->qsize = 1024*1024 ;
      } else {
          if (x->qsize == 0)
              x->qsize = 50 ;
          if (x->qsize > 100)
              x->qsize = 50 ;
      }
      /* configuring RED */
      if ( x->flags_fs & DN_IS_RED )
          config_red(src, x) ;    /* XXX should check errors */
  }
  
  /*
   * setup pipe or queue parameters.
   */
  
  static int
  config_pipe(struct dn_pipe *p)
  {
      int i, r;
      struct dn_flow_set *pfs = &(p->fs);
      struct dn_flow_queue *q;
  
      /*
       * The config program passes parameters as follows:
       * bw = bits/second (0 means no limits),
       * delay = ms, must be translated into ticks.
       * qsize = slots/bytes
       */
      p->delay = ( p->delay * hz ) / 1000 ;
      /* We need either a pipe number or a flow_set number */
      if (p->pipe_nr == 0 && pfs->fs_nr == 0)
          return EINVAL ;
      if (p->pipe_nr != 0 && pfs->fs_nr != 0)
          return EINVAL ;
      if (p->pipe_nr != 0) { /* this is a pipe */
          struct dn_pipe *x, *a, *b;
  
          DUMMYNET_LOCK();
          /* locate pipe */
          for (a = NULL , b = all_pipes ; b && b->pipe_nr < p->pipe_nr ;
                   a = b , b = b->next) ;
  
          if (b == NULL || b->pipe_nr != p->pipe_nr) { /* new pipe */
              x = malloc(sizeof(struct dn_pipe), M_DUMMYNET, M_NOWAIT | M_ZERO);
              if (x == NULL) {
                  printf("dummynet: no memory for new pipe\n");
                  return ENOSPC;
              }
              x->pipe_nr = p->pipe_nr;
              x->fs.pipe = x ;
              /* idle_heap is the only one from which we extract from the middle.
               */
              x->idle_heap.size = x->idle_heap.elements = 0 ;
              x->idle_heap.offset=OFFSET_OF(struct dn_flow_queue, heap_pos);
          } else {
              x = b;
              /* Flush accumulated credit for all queues */
              for (i = 0; i <= x->fs.rq_size; i++)
                  for (q = x->fs.rq[i]; q; q = q->next)
                      q->numbytes = 0;
          }
  
          x->bandwidth = p->bandwidth ;
          x->numbytes = 0; /* just in case... */
          bcopy(p->if_name, x->if_name, sizeof(p->if_name) );
          x->ifp = NULL ; /* reset interface ptr */
          x->delay = p->delay ;
          set_fs_parms(&(x->fs), pfs);
  
  
          if ( x->fs.rq == NULL ) { /* a new pipe */
              r = alloc_hash(&(x->fs), pfs) ;
              if (r) {
                  DUMMYNET_UNLOCK();
                  free(x, M_DUMMYNET);
                  return r ;
              }
              x->next = b ;
              if (a == NULL)
                  all_pipes = x ;
              else
                  a->next = x ;
          }
          DUMMYNET_UNLOCK();
      } else { /* config queue */
          struct dn_flow_set *x, *a, *b ;
  
          DUMMYNET_LOCK();
          /* locate flow_set */
          for (a=NULL, b=all_flow_sets ; b && b->fs_nr < pfs->fs_nr ;
                   a = b , b = b->next) ;
  
          if (b == NULL || b->fs_nr != pfs->fs_nr) { /* new  */
              if (pfs->parent_nr == 0)    /* need link to a pipe */
                  return EINVAL ;
              x = malloc(sizeof(struct dn_flow_set), M_DUMMYNET, M_NOWAIT|M_ZERO);
              if (x == NULL) {
                  DUMMYNET_UNLOCK();
                  printf("dummynet: no memory for new flow_set\n");
                  return ENOSPC;
              }
              x->fs_nr = pfs->fs_nr;
              x->parent_nr = pfs->parent_nr;
              x->weight = pfs->weight ;
              if (x->weight == 0)
                  x->weight = 1 ;
              else if (x->weight > 100)
                  x->weight = 100 ;
          } else {
              /* Change parent pipe not allowed; must delete and recreate */
              if (pfs->parent_nr != 0 && b->parent_nr != pfs->parent_nr)
                  return EINVAL ;
              x = b;
          }
          set_fs_parms(x, pfs);
  
          if ( x->rq == NULL ) { /* a new flow_set */
              r = alloc_hash(x, pfs) ;
              if (r) {
                  DUMMYNET_UNLOCK();
                  free(x, M_DUMMYNET);
                  return r ;
              }
              x->next = b;
              if (a == NULL)
                  all_flow_sets = x;
              else
                  a->next = x;
          }
          DUMMYNET_UNLOCK();
      }
      return 0 ;
  }
  
  /*
   * Helper function to remove from a heap queues which are linked to
   * a flow_set about to be deleted.
   */
  static void
  fs_remove_from_heap(struct dn_heap *h, struct dn_flow_set *fs)
  {
      int i = 0, found = 0 ;
      for (; i < h->elements ;)
          if ( ((struct dn_flow_queue *)h->p[i].object)->fs == fs) {
              h->elements-- ;
              h->p[i] = h->p[h->elements] ;
              found++ ;
          } else
              i++ ;
      if (found)
          heapify(h);
  }
  
  /*
   * helper function to remove a pipe from a heap (can be there at most once)
   */
  static void
  pipe_remove_from_heap(struct dn_heap *h, struct dn_pipe *p)
  {
      if (h->elements > 0) {
          int i = 0 ;
          for (i=0; i < h->elements ; i++ ) {
              if (h->p[i].object == p) { /* found it */
                  h->elements-- ;
                  h->p[i] = h->p[h->elements] ;
                  heapify(h);
                  break ;
              }
          }
      }
  }
  
  /*
   * drain all queues. Called in case of severe mbuf shortage.
   */
  void
  dummynet_drain()
  {
      struct dn_flow_set *fs;
      struct dn_pipe *p;
      struct dn_pkt *pkt;
  
      DUMMYNET_LOCK_ASSERT();
  
      heap_free(&ready_heap);
      heap_free(&wfq_ready_heap);
      heap_free(&extract_heap);
      /* remove all references to this pipe from flow_sets */
      for (fs = all_flow_sets; fs; fs= fs->next )
          purge_flow_set(fs, 0);
  
      for (p = all_pipes; p; p= p->next ) {
          purge_flow_set(&(p->fs), 0);
          for (pkt = p->head ; pkt ; )
              DN_FREE_PKT(pkt) ;
          p->head = p->tail = NULL ;
      }
  }
  
  /*
   * Fully delete a pipe or a queue, cleaning up associated info.
   */
  static int
  delete_pipe(struct dn_pipe *p)
  {
      if (p->pipe_nr == 0 && p->fs.fs_nr == 0)
          return EINVAL ;
      if (p->pipe_nr != 0 && p->fs.fs_nr != 0)
          return EINVAL ;
      if (p->pipe_nr != 0) { /* this is an old-style pipe */
          struct dn_pipe *a, *b;
          struct dn_flow_set *fs;
  
          DUMMYNET_LOCK();
          /* locate pipe */
          for (a = NULL , b = all_pipes ; b && b->pipe_nr < p->pipe_nr ;
                   a = b , b = b->next) ;
          if (b == NULL || (b->pipe_nr != p->pipe_nr) ) {
              DUMMYNET_UNLOCK();
              return EINVAL ; /* not found */
          }
  
          /* unlink from list of pipes */
          if (a == NULL)
              all_pipes = b->next ;
          else
              a->next = b->next ;
          /* remove references to this pipe from the ip_fw rules. */
          flush_pipe_ptrs(&(b->fs));
  
          /* remove all references to this pipe from flow_sets */
          for (fs = all_flow_sets; fs; fs= fs->next )
              if (fs->pipe == b) {
                  printf("dummynet: ++ ref to pipe %d from fs %d\n",
                          p->pipe_nr, fs->fs_nr);
                  fs->pipe = NULL ;
                  purge_flow_set(fs, 0);
              }
          fs_remove_from_heap(&ready_heap, &(b->fs));
          purge_pipe(b);  /* remove all data associated to this pipe */
          /* remove reference to here from extract_heap and wfq_ready_heap */
          pipe_remove_from_heap(&extract_heap, b);
          pipe_remove_from_heap(&wfq_ready_heap, b);
          DUMMYNET_UNLOCK();
  
          free(b, M_DUMMYNET);
      } else { /* this is a WF2Q queue (dn_flow_set) */
          struct dn_flow_set *a, *b;
  
          DUMMYNET_LOCK();
          /* locate set */
          for (a = NULL, b = all_flow_sets ; b && b->fs_nr < p->fs.fs_nr ;
                   a = b , b = b->next) ;
          if (b == NULL || (b->fs_nr != p->fs.fs_nr) ) {
              DUMMYNET_UNLOCK();
              return EINVAL ; /* not found */
          }
  
          if (a == NULL)
              all_flow_sets = b->next ;
          else
              a->next = b->next ;
          /* remove references to this flow_set from the ip_fw rules. */
          flush_pipe_ptrs(b);
  
          if (b->pipe != NULL) {
              /* Update total weight on parent pipe and cleanup parent heaps */
              b->pipe->sum -= b->weight * b->backlogged ;
              fs_remove_from_heap(&(b->pipe->not_eligible_heap), b);
              fs_remove_from_heap(&(b->pipe->scheduler_heap), b);
  #if 1   /* XXX should i remove from idle_heap as well ? */
              fs_remove_from_heap(&(b->pipe->idle_heap), b);
  #endif
          }
          purge_flow_set(b, 1);
          DUMMYNET_UNLOCK();
      }
      return 0 ;
  }
  
  /*
   * helper function used to copy data from kernel in DUMMYNET_GET
   */
  static char *
  dn_copy_set(struct dn_flow_set *set, char *bp)
  {
      int i, copied = 0 ;
      struct dn_flow_queue *q, *qp = (struct dn_flow_queue *)bp;
  
      DUMMYNET_LOCK_ASSERT();
  
      for (i = 0 ; i <= set->rq_size ; i++)
          for (q = set->rq[i] ; q ; q = q->next, qp++ ) {
              if (q->hash_slot != i)
                  printf("dummynet: ++ at %d: wrong slot (have %d, "
                      "should be %d)\n", copied, q->hash_slot, i);
              if (q->fs != set)
                  printf("dummynet: ++ at %d: wrong fs ptr (have %p, should be %p)\n",
                          i, q->fs, set);
              copied++ ;
              bcopy(q, qp, sizeof( *q ) );
              /* cleanup pointers */
              qp->next = NULL ;
              qp->head = qp->tail = NULL ;
              qp->fs = NULL ;
          }
      if (copied != set->rq_elements)
          printf("dummynet: ++ wrong count, have %d should be %d\n",
              copied, set->rq_elements);
      return (char *)qp ;
  }
  
  static int
  dummynet_get(struct sockopt *sopt)
  {
      char *buf, *bp ; /* bp is the "copy-pointer" */
      size_t size ;
      struct dn_flow_set *set ;
      struct dn_pipe *p ;
      int error=0 ;
  
      /* XXX lock held too long */
      DUMMYNET_LOCK();
      /*
       * compute size of data structures: list of pipes and flow_sets.
       */
      for (p = all_pipes, size = 0 ; p ; p = p->next )
          size += sizeof( *p ) +
              p->fs.rq_elements * sizeof(struct dn_flow_queue);
      for (set = all_flow_sets ; set ; set = set->next )
          size += sizeof ( *set ) +
              set->rq_elements * sizeof(struct dn_flow_queue);
      buf = malloc(size, M_TEMP, M_NOWAIT);
      if (buf == 0) {
          DUMMYNET_UNLOCK();
          return ENOBUFS ;
      }
      for (p = all_pipes, bp = buf ; p ; p = p->next ) {
          struct dn_pipe *pipe_bp = (struct dn_pipe *)bp ;
  
          /*
           * copy pipe descriptor into *bp, convert delay back to ms,
           * then copy the flow_set descriptor(s) one at a time.
           * After each flow_set, copy the queue descriptor it owns.
           */
          bcopy(p, bp, sizeof( *p ) );
          pipe_bp->delay = (pipe_bp->delay * 1000) / hz ;
          /*
           * XXX the following is a hack based on ->next being the
           * first field in dn_pipe and dn_flow_set. The correct
           * solution would be to move the dn_flow_set to the beginning
           * of struct dn_pipe.
           */
          pipe_bp->next = (struct dn_pipe *)DN_IS_PIPE ;
          /* clean pointers */
          pipe_bp->head = pipe_bp->tail = NULL ;
          pipe_bp->fs.next = NULL ;
          pipe_bp->fs.pipe = NULL ;
          pipe_bp->fs.rq = NULL ;
  
          bp += sizeof( *p ) ;
          bp = dn_copy_set( &(p->fs), bp );
      }
      for (set = all_flow_sets ; set ; set = set->next ) {
          struct dn_flow_set *fs_bp = (struct dn_flow_set *)bp ;
          bcopy(set, bp, sizeof( *set ) );
          /* XXX same hack as above */
          fs_bp->next = (struct dn_flow_set *)DN_IS_QUEUE ;
          fs_bp->pipe = NULL ;
          fs_bp->rq = NULL ;
          bp += sizeof( *set ) ;
          bp = dn_copy_set( set, bp );
      }
      DUMMYNET_UNLOCK();
  
      error = sooptcopyout(sopt, buf, size);
      free(buf, M_TEMP);
      return error ;
  }
  
  /*
   * Handler for the various dummynet socket options (get, flush, config, del)
   */
  static int
  ip_dn_ctl(struct sockopt *sopt)
  {
      int error = 0 ;
      struct dn_pipe *p, tmp_pipe;
  
      /* Disallow sets in really-really secure mode. */
      if (sopt->sopt_dir == SOPT_SET) {
  #if __FreeBSD_version >= 500034
          error =  securelevel_ge(sopt->sopt_td->td_ucred, 3);
          if (error)
              return (error);
  #else
          if (securelevel >= 3)
              return (EPERM);
  #endif
      }
  
      switch (sopt->sopt_name) {
      default :
          printf("dummynet: -- unknown option %d", sopt->sopt_name);
          return EINVAL ;
  
      case IP_DUMMYNET_GET :
          error = dummynet_get(sopt);
          break ;
  
      case IP_DUMMYNET_FLUSH :
          dummynet_flush() ;
          break ;
  
      case IP_DUMMYNET_CONFIGURE :
          p = &tmp_pipe ;
          error = sooptcopyin(sopt, p, sizeof *p, sizeof *p);
          if (error)
              break ;
          error = config_pipe(p);
          break ;
  
      case IP_DUMMYNET_DEL :      /* remove a pipe or queue */
          p = &tmp_pipe ;
          error = sooptcopyin(sopt, p, sizeof *p, sizeof *p);
          if (error)
              break ;
  
          error = delete_pipe(p);
          break ;
      }
      return error ;
  }
  
  static void
  ip_dn_init(void)
  {
      if (bootverbose)
              printf("DUMMYNET initialized (011031)\n");
  
      DUMMYNET_LOCK_INIT();
  
      all_pipes = NULL ;
      all_flow_sets = NULL ;
      ready_heap.size = ready_heap.elements = 0 ;
      ready_heap.offset = 0 ;
  
      wfq_ready_heap.size = wfq_ready_heap.elements = 0 ;
      wfq_ready_heap.offset = 0 ;
  
      extract_heap.size = extract_heap.elements = 0 ;
      extract_heap.offset = 0 ;
  
      ip_dn_ctl_ptr = ip_dn_ctl;
      ip_dn_io_ptr = dummynet_io;
      ip_dn_ruledel_ptr = dn_rule_delete;
  
      callout_init(&dn_timeout, debug_mpsafenet ? CALLOUT_MPSAFE : 0);
      callout_reset(&dn_timeout, 1, dummynet, NULL);
  }
  
  #ifdef KLD_MODULE
  static void
  ip_dn_destroy(void)
  {
      ip_dn_ctl_ptr = NULL;
      ip_dn_io_ptr = NULL;
      ip_dn_ruledel_ptr = NULL;
  
      callout_stop(&dn_timeout);
      dummynet_flush();
  
      DUMMYNET_LOCK_DESTROY();
  }
  #endif /* KLD_MODULE */
  
  static int
  dummynet_modevent(module_t mod, int type, void *data)
  {
          switch (type) {
          case MOD_LOAD:
                  if (DUMMYNET_LOADED) {
                      printf("DUMMYNET already loaded\n");
                      return EEXIST ;
                  }
                  ip_dn_init();
                  break;
  
          case MOD_UNLOAD:
  #if !defined(KLD_MODULE)
                  printf("dummynet statically compiled, cannot unload\n");
                  return EINVAL ;
  #else
                  ip_dn_destroy();
  #endif
                  break ;
          default:
                  break ;
          }
          return 0 ;
  }
  
  static moduledata_t dummynet_mod = {
          "dummynet",
          dummynet_modevent,
          NULL
  };
  DECLARE_MODULE(dummynet, dummynet_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
  MODULE_DEPEND(dummynet, ipfw, 1, 1, 1);
  MODULE_VERSION(dummynet, 1);

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