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.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #define DUMMYNET_DEBUG
    
    #include "opt_inet6.h"
    
    /*
     * 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 <sys/taskqueue.h>
    #include <net/if.h>
    #include <net/netisr.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 <netinet/ip6.h>       /* for ip6_input, ip6_output prototypes */
    #include <netinet6/ip6_var.h>
    
    /*
     * We keep a private variable for the simulation time, but we could
     * probably use an existing one ("softticks" in sys/kern/kern_timeout.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 long 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 */
   
   static struct timeval prev_t, t;
   static long tick_last;                  /* Last tick duration (usec). */
   static long tick_delta;                 /* Last vs standard tick diff (usec). */
   static long tick_delta_sum;             /* Accumulated tick difference (usec).*/
   static long tick_adjustment;            /* Tick adjustments done. */
   static long tick_lost;                  /* Lost(coalesced) ticks number. */
   /* Adjusted vs non-adjusted curr_time difference (ticks). */
   static long tick_diff;
   
   /*
    * 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, struct mbuf **head,
                       struct mbuf **tail);
   static void     ready_event(struct dn_flow_queue *q, struct mbuf **head,
                       struct mbuf **tail);
   static void     ready_event_wfq(struct dn_pipe *p, struct mbuf **head,
                       struct mbuf **tail);
   
   #define HASHSIZE        16
   #define HASH(num)       ((((num) >> 8) ^ ((num) >> 4) ^ (num)) & 0x0f)
   static struct dn_pipe_head      pipehash[HASHSIZE];     /* all pipes */
   static struct dn_flow_set_head  flowsethash[HASHSIZE];  /* all flowsets */
   
   static struct callout dn_timeout;
   
   extern  void (*bridge_dn_p)(struct mbuf *, struct ifnet *);
   
   #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_LONG(_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_LONG(_net_inet_ip_dummynet, OID_AUTO, searches,
       CTLFLAG_RD, &searches, 0, "Number of queue searches");
   SYSCTL_LONG(_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");
   SYSCTL_LONG(_net_inet_ip_dummynet, OID_AUTO, tick_delta,
       CTLFLAG_RD, &tick_delta, 0, "Last vs standard tick difference (usec).");
   SYSCTL_LONG(_net_inet_ip_dummynet, OID_AUTO, tick_delta_sum,
       CTLFLAG_RD, &tick_delta_sum, 0, "Accumulated tick difference (usec).");
   SYSCTL_LONG(_net_inet_ip_dummynet, OID_AUTO, tick_adjustment,
       CTLFLAG_RD, &tick_adjustment, 0, "Tick adjustments done.");
   SYSCTL_LONG(_net_inet_ip_dummynet, OID_AUTO, tick_diff,
       CTLFLAG_RD, &tick_diff, 0,
       "Adjusted vs non-adjusted curr_time difference (ticks).");
   SYSCTL_LONG(_net_inet_ip_dummynet, OID_AUTO, tick_lost,
       CTLFLAG_RD, &tick_lost, 0,
       "Number of ticks coalesced by dummynet taskqueue.");
   #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 task      dn_task;
   static struct taskqueue *dn_tq = NULL;
   static void dummynet_task(void *, int);
   
   static struct mtx dummynet_mtx;
   #define DUMMYNET_LOCK_INIT() \
           mtx_init(&dummynet_mtx, "dummynet", NULL, MTX_DEF)
   #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 dummynet(void *);
   static void dummynet_flush(void);
   static void dummynet_send(struct mbuf *);
   void dummynet_drain(void);
   static ip_dn_io_t dummynet_io;
   static void dn_rule_delete(void *);
   
   /*
    * 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 ---
    */
   
   /*
    * Return the mbuf tag holding the dummynet state.  As an optimization
    * this is assumed to be the first tag on the list.  If this turns out
    * wrong we'll need to search the list.
    */
   static struct dn_pkt_tag *
   dn_tag_get(struct mbuf *m)
   {
       struct m_tag *mtag = m_tag_first(m);
       KASSERT(mtag != NULL &&
               mtag->m_tag_cookie == MTAG_ABI_COMPAT &&
               mtag->m_tag_id == PACKET_TAG_DUMMYNET,
               ("packet on dummynet queue w/o dummynet tag!"));
       return (struct dn_pkt_tag *)(mtag+1);
   }
   
   /*
    * 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 mbuf **head, struct mbuf **tail)
   {
           struct mbuf *m;
           struct dn_pkt_tag *pkt;
   
           DUMMYNET_LOCK_ASSERT();
   
           while ((m = pipe->head) != NULL) {
                   pkt = dn_tag_get(m);
                   if (!DN_KEY_LEQ(pkt->output_time, curr_time))
                           break;
   
                   pipe->head = m->m_nextpkt;
                   if (*tail != NULL)
                           (*tail)->m_nextpkt = m;
                   else
                           *head = m;
                   *tail = m;
           }
           if (*tail != NULL)
                   (*tail)->m_nextpkt = NULL;
   
           /* If there are leftover packets, put into the heap for next event. */
           if ((m = pipe->head) != NULL) {
                   pkt = dn_tag_get(m);
                   /*
                    * XXX: Should check errors on heap_insert, by draining the
                    * whole pipe p and hoping in the future we are more successful.
                    */
                   heap_insert(&extract_heap, pkt->output_time, pipe);
           }
   }
   
   /*
    * 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(_m, q, p)     \
       ((_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 mbuf *pkt, struct dn_flow_queue *q, struct dn_pipe *p,
       int len)
   {
       struct dn_pkt_tag *dt = dn_tag_get(pkt);
   
       q->head = pkt->m_nextpkt ;
       q->len-- ;
       q->len_bytes -= len ;
   
       dt->output_time = curr_time + p->delay ;
   
       if (p->head == NULL)
           p->head = pkt;
       else
           p->tail->m_nextpkt = pkt;
       p->tail = pkt;
       p->tail->m_nextpkt = 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 mbuf **head, struct mbuf **tail)
   {
       struct mbuf *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->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() now.
        * Otherwise, the scheduler will take care of it.
        */
       if (p_was_empty)
           transmit_event(p, head, tail);
   }
   
   /*
    * 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, struct mbuf **head, struct mbuf **tail)
   {
       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 mbuf *pkt = q->head;
               struct dn_flow_set *fs = q->fs;
               u_int64_t len = pkt->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)->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 ;
           dn_tag_get(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() now.
        * Otherwise, the scheduler will take care of it.
        */
       if (p_was_empty)
           transmit_event(p, head, tail);
   }
   
   /*
    * This is called one tick, after previous run. It is used to
    * schedule next run.
    */
   static void
   dummynet(void * __unused unused)
   {
   
           taskqueue_enqueue(dn_tq, &dn_task);
   }
   
   /*
    * The main dummynet processing function.
    */
   static void
   dummynet_task(void *context, int pending)
   {
           struct mbuf *head = NULL, *tail = NULL;
           struct dn_pipe *pipe;
           struct dn_heap *heaps[3];
           struct dn_heap *h;
           void *p;        /* generic parameter to handler */
           int i;
   
           DUMMYNET_LOCK();
   
           heaps[0] = &ready_heap;                 /* fixed-rate queues */
           heaps[1] = &wfq_ready_heap;             /* wfq queues */
           heaps[2] = &extract_heap;               /* delay line */
   
           /* Update number of lost(coalesced) ticks. */
           tick_lost += pending - 1;
    
           getmicrouptime(&t);
           /* Last tick duration (usec). */
           tick_last = (t.tv_sec - prev_t.tv_sec) * 1000000 +
               (t.tv_usec - prev_t.tv_usec);
           /* Last tick vs standard tick difference (usec). */
           tick_delta = (tick_last * hz - 1000000) / hz;
           /* Accumulated tick difference (usec). */
           tick_delta_sum += tick_delta;
    
           prev_t = t;
    
           /*
            * Adjust curr_time if accumulated tick difference greater than
            * 'standard' tick. Since curr_time should be monotonically increasing,
            * we do positive adjustment as required and throttle curr_time in
            * case of negative adjustment.
            */
           curr_time++;
           if (tick_delta_sum - tick >= 0) {
                   int diff = tick_delta_sum / tick;
    
                   curr_time += diff;
                   tick_diff += diff;
                   tick_delta_sum %= tick;
                   tick_adjustment++;
           } else if (tick_delta_sum + tick <= 0) {
                   curr_time--;
                   tick_diff--;
                   tick_delta_sum += tick;
                   tick_adjustment++;
           }
   
           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));
                           /* store a copy before heap_extract */
                           p = h->p[0].object;
                           /* need to extract before processing */
                           heap_extract(h, NULL);
                           if (i == 0)
                                   ready_event(p, &head, &tail);
                           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, &head, &tail);
                           } else
                                   transmit_event(p, &head, &tail);
                   }
           }
   
           /* Sweep pipes trying to expire idle flow_queues. */
           for (i = 0; i < HASHSIZE; i++)
                   SLIST_FOREACH(pipe, &pipehash[i], next)
                           if (pipe->idle_heap.elements > 0 &&
                               DN_KEY_LT(pipe->idle_heap.p[0].key, pipe->V)) {
                                   struct dn_flow_queue *q =
                                       pipe->idle_heap.p[0].object;
   
                                   heap_extract(&(pipe->idle_heap), NULL);
                                   /* Mark timestamp as invalid. */
                                   q->S = q->F + 1;
                                   pipe->sum -= q->fs->weight;
                           }
   
           DUMMYNET_UNLOCK();
   
           if (head != NULL)
                   dummynet_send(head);
   
           callout_reset(&dn_timeout, 1, dummynet, NULL);
   }
   
   static void
   dummynet_send(struct mbuf *m)
   {
           struct dn_pkt_tag *pkt;
           struct mbuf *n;
           struct ip *ip;
   
           for (; m != NULL; m = n) {
                   n = m->m_nextpkt;
                   m->m_nextpkt = NULL;
                   pkt = dn_tag_get(m);
                   switch (pkt->dn_dir) {
                   case DN_TO_IP_OUT:
                           ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
                           break ;
                     case DN_TO_IP_IN :
                           ip = mtod(m, struct ip *);
                           ip->ip_len = htons(ip->ip_len);
                           ip->ip_off = htons(ip->ip_off);
                           netisr_dispatch(NETISR_IP, m);
                           break;
   #ifdef INET6
                   case DN_TO_IP6_IN:
                           netisr_dispatch(NETISR_IPV6, m);
                           break;
   
                   case DN_TO_IP6_OUT:
                           ip6_output(m, NULL, NULL, IPV6_FORWARDING, NULL, NULL, NULL);
                           break;
   #endif
                   case DN_TO_IFB_FWD:
                           if (bridge_dn_p != NULL)
                                   ((*bridge_dn_p)(m, pkt->ifp));
                           else
                                   printf("dummynet: if_bridge not loaded\n");
   
                           break;
                   case DN_TO_ETH_DEMUX:
                           /*
                            * The Ethernet code assumes the Ethernet header is
                            * contiguous in the first mbuf header.
                            * Insure this is true.
                            */
                           if (m->m_len < ETHER_HDR_LEN &&
                               (m = m_pullup(m, ETHER_HDR_LEN)) == NULL) {
                                   printf("dummynet/ether: pullup failed, "
                                       "dropping packet\n");
                                   break;
                           }
                           ether_demux(m->m_pkthdr.rcvif, m);
                           break;
                   case DN_TO_ETH_OUT:
                           ether_output_frame(pkt->ifp, m);
                           break;
                   default:
                           printf("dummynet: bad switch %d!\n", pkt->dn_dir);
                           m_freem(m);
                           break;
                   }
           }
   }
   
   /*
    * 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_uptime)
           return 0 ;
       fs->last_expired = time_uptime ;
       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;
       int is_v6 = IS_IP6_FLOW_ID(id);
   
       if ( !(fs->flags_fs & DN_HAVE_FLOW_MASK) )
           q = fs->rq[0] ;
       else {
           /* first, do the masking, then hash */
           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 */
           if (is_v6) {
               APPLY_MASK(&id->dst_ip6, &fs->flow_mask.dst_ip6);
               APPLY_MASK(&id->src_ip6, &fs->flow_mask.src_ip6);
               id->flow_id6 &= fs->flow_mask.flow_id6;
   
               i = ((id->dst_ip6.__u6_addr.__u6_addr32[0]) & 0xffff)^
                   ((id->dst_ip6.__u6_addr.__u6_addr32[1]) & 0xffff)^
                   ((id->dst_ip6.__u6_addr.__u6_addr32[2]) & 0xffff)^
                   ((id->dst_ip6.__u6_addr.__u6_addr32[3]) & 0xffff)^
   
                   ((id->dst_ip6.__u6_addr.__u6_addr32[0] >> 15) & 0xffff)^
                   ((id->dst_ip6.__u6_addr.__u6_addr32[1] >> 15) & 0xffff)^
                   ((id->dst_ip6.__u6_addr.__u6_addr32[2] >> 15) & 0xffff)^
                   ((id->dst_ip6.__u6_addr.__u6_addr32[3] >> 15) & 0xffff)^
   
                   ((id->src_ip6.__u6_addr.__u6_addr32[0] << 1) & 0xfffff)^
                   ((id->src_ip6.__u6_addr.__u6_addr32[1] << 1) & 0xfffff)^
                   ((id->src_ip6.__u6_addr.__u6_addr32[2] << 1) & 0xfffff)^
                   ((id->src_ip6.__u6_addr.__u6_addr32[3] << 1) & 0xfffff)^
   
                   ((id->src_ip6.__u6_addr.__u6_addr32[0] << 16) & 0xffff)^
                   ((id->src_ip6.__u6_addr.__u6_addr32[1] << 16) & 0xffff)^
                   ((id->src_ip6.__u6_addr.__u6_addr32[2] << 16) & 0xffff)^
                   ((id->src_ip6.__u6_addr.__u6_addr32[3] << 16) & 0xffff)^
   
                   (id->dst_port << 1) ^ (id->src_port) ^
                   (id->proto ) ^
                   (id->flow_id6);
          } else {
              id->dst_ip &= fs->flow_mask.dst_ip ;
              id->src_ip &= fs->flow_mask.src_ip ;
  
              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 (is_v6 &&
                      IN6_ARE_ADDR_EQUAL(&id->dst_ip6,&q->id.dst_ip6) &&  
                      IN6_ARE_ADDR_EQUAL(&id->src_ip6,&q->id.src_ip6) &&  
                      id->dst_port == q->id.dst_port &&
                      id->src_port == q->id.src_port &&
                      id->proto == q->id.proto &&
                      id->flags == q->id.flags &&
                      id->flow_id6 == q->id.flow_id6)
                  break ; /* found */
  
              if (!is_v6 && 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 */
  
              /* No match. Check if we can expire the entry */
              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
                           *       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)
                   *       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 fs_nr)
  {
          struct dn_flow_set *fs;
  
          SLIST_FOREACH(fs, &flowsethash[HASH(fs_nr)], next)
                  if (fs->fs_nr == fs_nr)
                          return (fs);
  
          return (NULL);
  }
  
  static __inline struct dn_pipe *
  locate_pipe(int pipe_nr)
  {
          struct dn_pipe *pipe;
  
          SLIST_FOREACH(pipe, &pipehash[HASH(pipe_nr)], next)
                  if (pipe->pipe_nr == pipe_nr)
                          return (pipe);
  
          return (NULL);
  }
  
  /*
   * 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,
   * rule         matching rule, in case of multiple passes
   *
   */
  static int
  dummynet_io(struct mbuf *m, int dir, struct ip_fw_args *fwa)
  {
      struct mbuf *head = NULL, *tail = NULL;
      struct dn_pkt_tag *pkt;
      struct m_tag *mtag;
      struct dn_flow_set *fs = NULL;
      struct dn_pipe *pipe ;
      u_int64_t len = m->m_pkthdr.len ;
      struct dn_flow_queue *q = NULL ;
      int is_pipe;
      ipfw_insn *cmd = ACTION_PTR(fwa->rule);
  
      KASSERT(m->m_nextpkt == NULL,
          ("dummynet_io: mbuf queue passed to dummynet"));
  
      if (cmd->opcode == O_LOG)
          cmd += F_LEN(cmd);
      if (cmd->opcode == O_ALTQ)
          cmd += F_LEN(cmd);
      if (cmd->opcode == O_TAG)
          cmd += F_LEN(cmd);
      is_pipe = (cmd->opcode == O_PIPE);
  
      DUMMYNET_LOCK();
      /*
       * This is a dummynet rule, so we expect an O_PIPE or O_QUEUE rule.
       *
       * XXXGL: probably the pipe->fs and fs->pipe logic here
       * below can be simplified.
       */
      if (is_pipe) {
          pipe = locate_pipe(fwa->cookie);
          if (pipe != NULL)
                  fs = &(pipe->fs);
      } else
          fs = locate_flowset(fwa->cookie);
  
      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. */
          pipe = locate_pipe(fs->parent_nr);
          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*/
      mtag = m_tag_get(PACKET_TAG_DUMMYNET,
                  sizeof(struct dn_pkt_tag), M_NOWAIT|M_ZERO);
      if ( mtag == NULL )
          goto dropit ;           /* cannot allocate packet header        */
      m_tag_prepend(m, mtag);     /* attach to mbuf chain */
  
      pkt = (struct dn_pkt_tag *)(mtag+1);
      /* ok, i can handle the pkt now... */
      /* build and enqueue packet + parameters */
      pkt->rule = fwa->rule ;
      pkt->dn_dir = dir ;
  
      pkt->ifp = fwa->oif;
  
      if (q->head == NULL)
          q->head = m;
      else
          q->tail->m_nextpkt = m;
      q->tail = m;
      q->len++;
      q->len_bytes += len ;
  
      if ( q->head != m )         /* 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(m, q, pipe);
          q->sched_time = curr_time ;
          if (t == 0)     /* must process it now */
              ready_event(q, &head, &tail);
          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, &head, &tail);
              }
          }
      }
  done:
      DUMMYNET_UNLOCK();
      if (head != NULL)
          dummynet_send(head);
      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(_m) do {                            \
          m_freem(_m);                                    \
  } while (0)
  
  /*
   * 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_flow_queue *q, *qn;
          int i;
  
          DUMMYNET_LOCK_ASSERT();
  
          for (i = 0; i <= fs->rq_size; i++) {
                  for (q = fs->rq[i]; q != NULL; q = qn) {
                          struct mbuf *m, *mnext;
  
                          mnext = q->head;
                          while ((m = mnext) != NULL) {
                                  mnext = m->m_nextpkt;
                                  DN_FREE_PKT(m);
                          }
                          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 != NULL)
                          free(fs->w_q_lookup, M_DUMMYNET);
                  if (fs->rq != NULL)
                          free(fs->rq, M_DUMMYNET);
                  /* If this fs is not part of a pipe, free it. */
                  if (fs->pipe == NULL || 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 mbuf *m, *mnext;
  
      purge_flow_set( &(pipe->fs), 1 );
  
      mnext = pipe->head;
      while ((m = mnext) != NULL) {
          mnext = m->m_nextpkt;
          DN_FREE_PKT(m);
      }
  
      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(void)
  {
          struct dn_pipe *pipe, *pipe1;
          struct dn_flow_set *fs, *fs1;
          int i;
  
          DUMMYNET_LOCK();
          /* 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.
           *
           * XXXGL: can we merge the for(;;) cycles into one or not?
           */
          for (i = 0; i < HASHSIZE; i++)
                  SLIST_FOREACH_SAFE(fs, &flowsethash[i], next, fs1) {
                          SLIST_REMOVE(&flowsethash[i], fs, dn_flow_set, next);
                          purge_flow_set(fs, 1);
                  }
          for (i = 0; i < HASHSIZE; i++)
                  SLIST_FOREACH_SAFE(pipe, &pipehash[i], next, pipe1) {
                          SLIST_REMOVE(&pipehash[i], pipe, dn_pipe, next);
                          purge_pipe(pipe);
                          free(pipe, 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 mbuf *m ;
  
      for (i = 0 ; i <= fs->rq_size ; i++) /* last one is ovflow */
          for (q = fs->rq[i] ; q ; q = q->next )
              for (m = q->head ; m ; m = m->m_nextpkt ) {
                  struct dn_pkt_tag *pkt = dn_tag_get(m) ;
                  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 *pipe;
      struct dn_flow_set *fs;
      struct dn_pkt_tag *pkt;
      struct mbuf *m;
      int i;
  
      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 (i = 0; i < HASHSIZE; i++)
          SLIST_FOREACH(fs, &flowsethash[i], next)
                  dn_rule_delete_fs(fs, r);
  
      for (i = 0; i < HASHSIZE; i++)
          SLIST_FOREACH(pipe, &pipehash[i], next) {
                  fs = &(pipe->fs);
                  dn_rule_delete_fs(fs, r);
                  for (m = pipe->head ; m ; m = m->m_nextpkt ) {
                          pkt = dn_tag_get(m);
                          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 (ENOMEM);
      }
      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)
  {
          struct dn_flow_set *pfs = &(p->fs);
          struct dn_flow_queue *q;
          int i, error;
  
          /*
           * 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 *pipe;
  
                  DUMMYNET_LOCK();
                  pipe = locate_pipe(p->pipe_nr); /* locate pipe */
  
                  if (pipe == NULL) {             /* new pipe */
                          pipe = malloc(sizeof(struct dn_pipe), M_DUMMYNET,
                              M_NOWAIT | M_ZERO);
                          if (pipe == NULL) {
                                  DUMMYNET_UNLOCK();
                                  printf("dummynet: no memory for new pipe\n");
                                  return (ENOMEM);
                          }
                          pipe->pipe_nr = p->pipe_nr;
                          pipe->fs.pipe = pipe;
                          /*
                           * idle_heap is the only one from which
                           * we extract from the middle.
                           */
                          pipe->idle_heap.size = pipe->idle_heap.elements = 0;
                          pipe->idle_heap.offset =
                              offsetof(struct dn_flow_queue, heap_pos);
                  } else
                          /* Flush accumulated credit for all queues. */
                          for (i = 0; i <= pipe->fs.rq_size; i++)
                                  for (q = pipe->fs.rq[i]; q; q = q->next)
                                          q->numbytes = 0;
  
                  pipe->bandwidth = p->bandwidth;
                  pipe->numbytes = 0;             /* just in case... */
                  bcopy(p->if_name, pipe->if_name, sizeof(p->if_name));
                  pipe->ifp = NULL;               /* reset interface ptr */
                  pipe->delay = p->delay;
                  set_fs_parms(&(pipe->fs), pfs);
  
                  if (pipe->fs.rq == NULL) {      /* a new pipe */
                          error = alloc_hash(&(pipe->fs), pfs);
                          if (error) {
                                  DUMMYNET_UNLOCK();
                                  free(pipe, M_DUMMYNET);
                                  return (error);
                          }
                          SLIST_INSERT_HEAD(&pipehash[HASH(pipe->pipe_nr)],
                              pipe, next);
                  }
                  DUMMYNET_UNLOCK();
          } else {                                /* config queue */
                  struct dn_flow_set *fs;
  
                  DUMMYNET_LOCK();
                  fs = locate_flowset(pfs->fs_nr); /* locate flow_set */
  
                  if (fs == NULL) {               /* new */
                          if (pfs->parent_nr == 0) { /* need link to a pipe */
                                  DUMMYNET_UNLOCK();
                                  return (EINVAL);
                          }
                          fs = malloc(sizeof(struct dn_flow_set), M_DUMMYNET,
                              M_NOWAIT | M_ZERO);
                          if (fs == NULL) {
                                  DUMMYNET_UNLOCK();
                                  printf(
                                      "dummynet: no memory for new flow_set\n");
                                  return (ENOMEM);
                          }
                          fs->fs_nr = pfs->fs_nr;
                          fs->parent_nr = pfs->parent_nr;
                          fs->weight = pfs->weight;
                          if (fs->weight == 0)
                                  fs->weight = 1;
                          else if (fs->weight > 100)
                                  fs->weight = 100;
                  } else {
                          /*
                           * Change parent pipe not allowed;
                           * must delete and recreate.
                           */
                          if (pfs->parent_nr != 0 &&
                              fs->parent_nr != pfs->parent_nr) {
                                  DUMMYNET_UNLOCK();
                                  return (EINVAL);
                          }
                  }
  
                  set_fs_parms(fs, pfs);
  
                  if (fs->rq == NULL) {           /* a new flow_set */
                          error = alloc_hash(fs, pfs);
                          if (error) {
                                  DUMMYNET_UNLOCK();
                                  free(fs, M_DUMMYNET);
                                  return (error);
                          }
                          SLIST_INSERT_HEAD(&flowsethash[HASH(fs->fs_nr)],
                              fs, next);
                  }
                  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(void)
  {
      struct dn_flow_set *fs;
      struct dn_pipe *pipe;
      struct mbuf *m, *mnext;
      int i;
  
      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 (i = 0; i < HASHSIZE; i++)
          SLIST_FOREACH(fs, &flowsethash[i], next)
                  purge_flow_set(fs, 0);
  
      for (i = 0; i < HASHSIZE; i++) {
          SLIST_FOREACH(pipe, &pipehash[i], next) {
                  purge_flow_set(&(pipe->fs), 0);
  
                  mnext = pipe->head;
                  while ((m = mnext) != NULL) {
                          mnext = m->m_nextpkt;
                          DN_FREE_PKT(m);
                  }
                  pipe->head = pipe->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 *pipe;
          struct dn_flow_set *fs;
          int i;
  
          DUMMYNET_LOCK();
          pipe = locate_pipe(p->pipe_nr); /* locate pipe */
  
          if (pipe == NULL) {
              DUMMYNET_UNLOCK();
              return (ENOENT);    /* not found */
          }
  
          /* Unlink from list of pipes. */
          SLIST_REMOVE(&pipehash[HASH(pipe->pipe_nr)], pipe, dn_pipe, next);
  
          /* Remove all references to this pipe from flow_sets. */
          for (i = 0; i < HASHSIZE; i++)
              SLIST_FOREACH(fs, &flowsethash[i], next)
                  if (fs->pipe == pipe) {
                          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, &(pipe->fs));
          purge_pipe(pipe); /* remove all data associated to this pipe */
          /* remove reference to here from extract_heap and wfq_ready_heap */
          pipe_remove_from_heap(&extract_heap, pipe);
          pipe_remove_from_heap(&wfq_ready_heap, pipe);
          DUMMYNET_UNLOCK();
  
          free(pipe, M_DUMMYNET);
      } else { /* this is a WF2Q queue (dn_flow_set) */
          struct dn_flow_set *fs;
  
          DUMMYNET_LOCK();
          fs = locate_flowset(p->fs.fs_nr); /* locate set */
  
          if (fs == NULL) {
              DUMMYNET_UNLOCK();
              return (ENOENT); /* not found */
          }
  
          /* Unlink from list of flowsets. */
          SLIST_REMOVE( &flowsethash[HASH(fs->fs_nr)], fs, dn_flow_set, next);
  
          if (fs->pipe != NULL) {
              /* Update total weight on parent pipe and cleanup parent heaps. */
              fs->pipe->sum -= fs->weight * fs->backlogged ;
              fs_remove_from_heap(&(fs->pipe->not_eligible_heap), fs);
              fs_remove_from_heap(&(fs->pipe->scheduler_heap), fs);
  #if 1   /* XXX should i remove from idle_heap as well ? */
              fs_remove_from_heap(&(fs->pipe->idle_heap), fs);
  #endif
          }
          purge_flow_set(fs, 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 size_t
  dn_calc_size(void)
  {
      struct dn_flow_set *fs;
      struct dn_pipe *pipe;
      size_t size = 0;
      int i;
  
      DUMMYNET_LOCK_ASSERT();
      /*
       * Compute size of data structures: list of pipes and flow_sets.
       */
      for (i = 0; i < HASHSIZE; i++) {
          SLIST_FOREACH(pipe, &pipehash[i], next)
                  size += sizeof(*pipe) +
                      pipe->fs.rq_elements * sizeof(struct dn_flow_queue);
          SLIST_FOREACH(fs, &flowsethash[i], next)
                  size += sizeof (*fs) +
                      fs->rq_elements * sizeof(struct dn_flow_queue);
      }
      return size;
  }
  
  static int
  dummynet_get(struct sockopt *sopt)
  {
      char *buf, *bp ; /* bp is the "copy-pointer" */
      size_t size ;
      struct dn_flow_set *fs;
      struct dn_pipe *pipe;
      int error=0, i ;
  
      /* XXX lock held too long */
      DUMMYNET_LOCK();
      /*
       * XXX: Ugly, but we need to allocate memory with M_WAITOK flag and we
       *      cannot use this flag while holding a mutex.
       */
      for (i = 0; i < 10; i++) {
          size = dn_calc_size();
          DUMMYNET_UNLOCK();
          buf = malloc(size, M_TEMP, M_WAITOK);
          DUMMYNET_LOCK();
          if (size == dn_calc_size())
                  break;
          free(buf, M_TEMP);
          buf = NULL;
      }
      if (buf == NULL) {
          DUMMYNET_UNLOCK();
          return ENOBUFS ;
      }
      bp = buf;
      for (i = 0; i < HASHSIZE; i++)
          SLIST_FOREACH(pipe, &pipehash[i], 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(pipe, bp, sizeof(*pipe));
                  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.sle_next = (struct dn_pipe *)DN_IS_PIPE;
                  /* Clean pointers. */
                  pipe_bp->head = pipe_bp->tail = NULL;
                  pipe_bp->fs.next.sle_next = NULL;
                  pipe_bp->fs.pipe = NULL;
                  pipe_bp->fs.rq = NULL;
  
                  bp += sizeof(*pipe) ;
                  bp = dn_copy_set(&(pipe->fs), bp);
          }
  
      for (i = 0; i < HASHSIZE; i++)
          SLIST_FOREACH(fs, &flowsethash[i], next) {
                  struct dn_flow_set *fs_bp = (struct dn_flow_set *)bp;
  
                  bcopy(fs, bp, sizeof(*fs));
                  /* XXX same hack as above */
                  fs_bp->next.sle_next = (struct dn_flow_set *)DN_IS_QUEUE;
                  fs_bp->pipe = NULL;
                  fs_bp->rq = NULL;
                  bp += sizeof(*fs);
                  bp = dn_copy_set(fs, 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)
  {
          int i;
  
          if (bootverbose)
                  printf("DUMMYNET with IPv6 initialized (040826)\n");
  
          DUMMYNET_LOCK_INIT();
  
          for (i = 0; i < HASHSIZE; i++) {
                  SLIST_INIT(&pipehash[i]);
                  SLIST_INIT(&flowsethash[i]);
          }
          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;
  
          TASK_INIT(&dn_task, 0, dummynet_task, NULL);
          dn_tq = taskqueue_create_fast("dummynet", M_NOWAIT,
              taskqueue_thread_enqueue, &dn_tq);
          taskqueue_start_threads(&dn_tq, 1, PI_NET, "dummynet");
  
          callout_init(&dn_timeout, CALLOUT_MPSAFE);
          callout_reset(&dn_timeout, 1, dummynet, NULL);
  
          /* Initialize curr_time adjustment mechanics. */
          getmicrouptime(&prev_t);
  }
  
  #ifdef KLD_MODULE
  static void
  ip_dn_destroy(void)
  {
          ip_dn_ctl_ptr = NULL;
          ip_dn_io_ptr = NULL;
          ip_dn_ruledel_ptr = NULL;
  
          DUMMYNET_LOCK();
          callout_stop(&dn_timeout);
          DUMMYNET_UNLOCK();
          taskqueue_drain(dn_tq, &dn_task);
          taskqueue_free(dn_tq);
  
          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:
                  return EOPNOTSUPP;
                  break ;
          }
          return 0 ;
  }
  
  static moduledata_t dummynet_mod = {
          "dummynet",
          dummynet_modevent,
          NULL
  };
  DECLARE_MODULE(dummynet, dummynet_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
  MODULE_DEPEND(dummynet, ipfw, 2, 2, 2);
  MODULE_VERSION(dummynet, 1);

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