bsd/netinet/ip_dummynet.c

/*
 * Copyright (c) 2000-2024 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * 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: src/sys/netinet/ip_dummynet.c,v 1.84 2004/08/25 09:31:30 pjd Exp $
 */

#define DUMMYNET_DEBUG 0

/*
 * This module implements IP dummynet, a bandwidth limiter/delay emulator
 * 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:
 *
 * 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/queue.h>                  /* XXX */
#include <sys/kernel.h>
#include <sys/random.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/time.h>
#include <sys/sysctl.h>
#include <kern/debug.h>
#include <net/if.h>
#include <net/route.h>
#include <net/kpi_protocol.h>
#if DUMMYNET
#include <net/kpi_protocol.h>
#endif /* DUMMYNET */
#include <net/nwk_wq.h>
#include <net/pfvar.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_dummynet.h>
#include <netinet/ip_var.h>

#include <netinet/ip6.h>       /* for ip6_input, ip6_output prototypes */
#include <netinet6/ip6_var.h>

#include <stdbool.h>
#include <net/sockaddr_utils.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 */

/* this is for the timer that fires to call dummynet() - we only enable the timer when
 *       there are packets to process, otherwise it's disabled */
static int timer_enabled = 0;

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 */

static int serialize = 0;

/*
 * 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.
 *
 */
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 *__sized_by_or_null(size)p, size_t size);
static void heap_extract(struct dn_heap *h, void *__sized_by_or_null(size)obj, size_t size);


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);

#ifdef SYSCTL_NODE
/*
 * Sysctl handler for reading the heap sizes.
 */
static int dn_heap_size_sysctl SYSCTL_HANDLER_ARGS;
#endif /* SYSCTL_NODE */

/*
 * Packets are retrieved from queues in Dummynet in chains instead of
 * packet-by-packet.  The entire list of packets is first dequeued and
 * sent out by the following function.
 */
static void dummynet_send(struct mbuf *m);

#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 */

#ifdef SYSCTL_NODE

const caddr_t SYSCTL_READY_HEAP_ARG = __unsafe_forge_single(caddr_t, &ready_heap);
const caddr_t SYSCTL_EXTRACT_HEAP_ARG = __unsafe_forge_single(caddr_t, &extract_heap);

static int
dn_heap_size_sysctl SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg2)
	int error = 0;
	int heap_size;
	const caddr_t heap_selector =
	    __unsafe_forge_single(const caddr_t, arg1);

	if (heap_selector == SYSCTL_READY_HEAP_ARG) {
		heap_size = ready_heap.size;
	} else if (heap_selector == SYSCTL_EXTRACT_HEAP_ARG) {
		heap_size = extract_heap.size;
	} else {
		error = EINVAL;
		os_log_error(OS_LOG_DEFAULT, "Unrecognized heap selector");
	}

	if (error == 0) {
		error = SYSCTL_OUT(req, &heap_size, sizeof(heap_size));
	}

	return error;
}

SYSCTL_NODE(_net_inet_ip, OID_AUTO, dummynet,
    CTLFLAG_RW | CTLFLAG_LOCKED, 0, "Dummynet");
SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, hash_size,
    CTLFLAG_RW | CTLFLAG_LOCKED, &dn_hash_size, 0, "Default hash table size");
SYSCTL_QUAD(_net_inet_ip_dummynet, OID_AUTO, curr_time,
    CTLFLAG_RD | CTLFLAG_LOCKED, &curr_time, "Current tick");
SYSCTL_PROC(_net_inet_ip_dummynet, OID_AUTO, ready_heap,
    CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_LOCKED,
    SYSCTL_READY_HEAP_ARG, 0, dn_heap_size_sysctl,
    "I", "Size of ready heap");
SYSCTL_PROC(_net_inet_ip_dummynet, OID_AUTO, extract_heap,
    CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_LOCKED,
    SYSCTL_EXTRACT_HEAP_ARG, 0, dn_heap_size_sysctl,
    "I", "Size of extract heap");
SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, searches,
    CTLFLAG_RD | CTLFLAG_LOCKED, &searches, 0, "Number of queue searches");
SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, search_steps,
    CTLFLAG_RD | CTLFLAG_LOCKED, &search_steps, 0, "Number of queue search steps");
SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, expire,
    CTLFLAG_RW | CTLFLAG_LOCKED, &pipe_expire, 0, "Expire queue if empty");
SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, max_chain_len,
    CTLFLAG_RW | CTLFLAG_LOCKED, &dn_max_ratio, 0,
    "Max ratio between dynamic queues and buckets");
SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, red_lookup_depth,
    CTLFLAG_RD | CTLFLAG_LOCKED, &red_lookup_depth, 0, "Depth of RED lookup table");
SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, red_avg_pkt_size,
    CTLFLAG_RD | CTLFLAG_LOCKED, &red_avg_pkt_size, 0, "RED Medium packet size");
SYSCTL_INT(_net_inet_ip_dummynet, OID_AUTO, red_max_pkt_size,
    CTLFLAG_RD | CTLFLAG_LOCKED, &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 | CTLFLAG_LOCKED, &dummynet_debug,
    0, "control debugging printfs");
#endif
#define DPRINTF(X)      if (dummynet_debug) printf X
#define IP_DN_DBG_LOG(fmt, ...) os_log_error(OS_LOG_DEFAULT, "ip_dn_debug %s:%d : " fmt "\n", __func__, __LINE__, ## __VA_ARGS__)
#else
#define DPRINTF(X)
#define IP_DN_DBG_LOG(fmt, ...) do {} while (0)
#endif
#define IP_DN_ERR_LOG(fmt, ...) os_log_error(OS_LOG_DEFAULT, fmt, ## __VA_ARGS__)

/* dummynet lock */
static LCK_GRP_DECLARE(dn_mutex_grp, "dn");
static LCK_MTX_DECLARE(dn_mutex, &dn_mutex_grp);

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);
void dummynet_drain(void);
static ip_dn_io_t dummynet_io;

/*
 * Functions to copy dat from/to userspace.
 * Functions that operate with buffers use `__ended_by' sentinel
 * to avoid out-of-bounds memory accesses.
 */
static void cp_flow_set_to_64_user(struct dn_flow_set *set, struct dn_flow_set_64 *fs_bp);
static void cp_queue_to_64_user( struct dn_flow_queue *q, struct dn_flow_queue_64 *qp);
static char *cp_pipe_to_64_user(struct dn_pipe *p, char *bp __ended_by(bp_end), char *bp_end);
static char *dn_copy_set_64(struct dn_flow_set *set, char *bp __ended_by(bp_end), char *bp_end);
static int cp_pipe_from_user_64( struct sockopt *sopt, struct dn_pipe *p );

static void cp_flow_set_to_32_user(struct dn_flow_set *set, struct dn_flow_set_32 *fs_bp);
static void cp_queue_to_32_user( struct dn_flow_queue *q, struct dn_flow_queue_32 *qp);
static char *cp_pipe_to_32_user(struct dn_pipe *p, char *bp __ended_by(bp_end), char *bp_end);
static char *dn_copy_set_32(struct dn_flow_set *set, char *bp __ended_by(bp_end), char *bp_end);
static int cp_pipe_from_user_32( struct sockopt *sopt, struct dn_pipe *p );

static struct m_tag * m_tag_kalloc_dummynet(u_int32_t id, u_int16_t type, uint16_t len, int wait);
static void m_tag_kfree_dummynet(struct m_tag *tag);

struct eventhandler_lists_ctxt dummynet_evhdlr_ctxt;

uint32_t
my_random(void)
{
	uint32_t val;
	read_frandom(&val, sizeof(val));
	val &= 0x7FFFFFFF;

	return val;
}

/*
 * 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


int
cp_pipe_from_user_32( struct sockopt *sopt, struct dn_pipe *p )
{
	struct dn_pipe_32 user_pipe_32;
	int error = 0;

	error = sooptcopyin(sopt, &user_pipe_32, sizeof(struct dn_pipe_32), sizeof(struct dn_pipe_32));
	if (!error) {
		p->pipe_nr = user_pipe_32.pipe_nr;
		p->bandwidth = user_pipe_32.bandwidth;
		p->delay = user_pipe_32.delay;
		p->V = user_pipe_32.V;
		p->sum = user_pipe_32.sum;
		p->numbytes = user_pipe_32.numbytes;
		p->sched_time = user_pipe_32.sched_time;
		bcopy( user_pipe_32.if_name, p->if_name, IFNAMSIZ);
		p->if_name[IFNAMSIZ - 1] = '\0';
		p->ready = user_pipe_32.ready;

		p->fs.fs_nr = user_pipe_32.fs.fs_nr;
		p->fs.flags_fs = user_pipe_32.fs.flags_fs;
		p->fs.parent_nr = user_pipe_32.fs.parent_nr;
		p->fs.weight = user_pipe_32.fs.weight;
		p->fs.qsize = user_pipe_32.fs.qsize;
		p->fs.plr = user_pipe_32.fs.plr;
		p->fs.flow_mask = user_pipe_32.fs.flow_mask;
		p->fs.rq = NULL;
		p->fs.rq_size = user_pipe_32.fs.rq_size;
		p->fs.rq_elements = user_pipe_32.fs.rq_elements;
		p->fs.last_expired = user_pipe_32.fs.last_expired;
		p->fs.backlogged = user_pipe_32.fs.backlogged;
		p->fs.w_q = user_pipe_32.fs.w_q;
		p->fs.max_th = user_pipe_32.fs.max_th;
		p->fs.min_th = user_pipe_32.fs.min_th;
		p->fs.max_p = user_pipe_32.fs.max_p;
		p->fs.c_1 = user_pipe_32.fs.c_1;
		p->fs.c_2 = user_pipe_32.fs.c_2;
		p->fs.c_3 = user_pipe_32.fs.c_3;
		p->fs.c_4 = user_pipe_32.fs.c_4;
		p->fs.w_q_lookup = NULL;
		p->fs.lookup_depth = user_pipe_32.fs.lookup_depth;
		p->fs.lookup_step = user_pipe_32.fs.lookup_step;
		p->fs.lookup_weight = user_pipe_32.fs.lookup_weight;
		p->fs.avg_pkt_size = user_pipe_32.fs.avg_pkt_size;
		p->fs.max_pkt_size = user_pipe_32.fs.max_pkt_size;
	}
	return error;
}


int
cp_pipe_from_user_64( struct sockopt *sopt, struct dn_pipe *p )
{
	struct dn_pipe_64 user_pipe_64;
	int error = 0;

	error = sooptcopyin(sopt, &user_pipe_64, sizeof(struct dn_pipe_64), sizeof(struct dn_pipe_64));
	if (!error) {
		p->pipe_nr = user_pipe_64.pipe_nr;
		p->bandwidth = user_pipe_64.bandwidth;
		p->delay = user_pipe_64.delay;
		p->V = user_pipe_64.V;
		p->sum = user_pipe_64.sum;
		p->numbytes = user_pipe_64.numbytes;
		p->sched_time = user_pipe_64.sched_time;
		bcopy( user_pipe_64.if_name, p->if_name, IFNAMSIZ);
		p->if_name[IFNAMSIZ - 1] = '\0';
		p->ready = user_pipe_64.ready;

		p->fs.fs_nr = user_pipe_64.fs.fs_nr;
		p->fs.flags_fs = user_pipe_64.fs.flags_fs;
		p->fs.parent_nr = user_pipe_64.fs.parent_nr;
		p->fs.weight = user_pipe_64.fs.weight;
		p->fs.qsize = user_pipe_64.fs.qsize;
		p->fs.plr = user_pipe_64.fs.plr;
		p->fs.flow_mask = user_pipe_64.fs.flow_mask;
		p->fs.rq = NULL;
		p->fs.rq_size = user_pipe_64.fs.rq_size;
		p->fs.rq_elements = user_pipe_64.fs.rq_elements;
		p->fs.last_expired = user_pipe_64.fs.last_expired;
		p->fs.backlogged = user_pipe_64.fs.backlogged;
		p->fs.w_q = user_pipe_64.fs.w_q;
		p->fs.max_th = user_pipe_64.fs.max_th;
		p->fs.min_th = user_pipe_64.fs.min_th;
		p->fs.max_p = user_pipe_64.fs.max_p;
		p->fs.c_1 = user_pipe_64.fs.c_1;
		p->fs.c_2 = user_pipe_64.fs.c_2;
		p->fs.c_3 = user_pipe_64.fs.c_3;
		p->fs.c_4 = user_pipe_64.fs.c_4;
		p->fs.w_q_lookup = NULL;
		p->fs.lookup_depth = user_pipe_64.fs.lookup_depth;
		p->fs.lookup_step = user_pipe_64.fs.lookup_step;
		p->fs.lookup_weight = user_pipe_64.fs.lookup_weight;
		p->fs.avg_pkt_size = user_pipe_64.fs.avg_pkt_size;
		p->fs.max_pkt_size = user_pipe_64.fs.max_pkt_size;
	} else {
		IP_DN_ERR_LOG("Error copying pipe from user, %d", error);
	}
	return error;
}

static void
cp_flow_set_to_32_user(struct dn_flow_set *set, struct dn_flow_set_32 *fs_bp)
{
	fs_bp->fs_nr = set->fs_nr;
	fs_bp->flags_fs = set->flags_fs;
	fs_bp->parent_nr = set->parent_nr;
	fs_bp->weight = set->weight;
	fs_bp->qsize = set->qsize;
	fs_bp->plr = set->plr;
	fs_bp->flow_mask = set->flow_mask;
	fs_bp->rq_size = set->rq_size;
	fs_bp->rq_elements = set->rq_elements;
	fs_bp->last_expired = set->last_expired;
	fs_bp->backlogged = set->backlogged;
	fs_bp->w_q = set->w_q;
	fs_bp->max_th = set->max_th;
	fs_bp->min_th = set->min_th;
	fs_bp->max_p = set->max_p;
	fs_bp->c_1 = set->c_1;
	fs_bp->c_2 = set->c_2;
	fs_bp->c_3 = set->c_3;
	fs_bp->c_4 = set->c_4;
	fs_bp->w_q_lookup = CAST_DOWN_EXPLICIT(user32_addr_t, VM_KERNEL_ADDRHIDE(set->w_q_lookup));
	fs_bp->lookup_depth = set->lookup_depth;
	fs_bp->lookup_step = set->lookup_step;
	fs_bp->lookup_weight = set->lookup_weight;
	fs_bp->avg_pkt_size = set->avg_pkt_size;
	fs_bp->max_pkt_size = set->max_pkt_size;
}

static void
cp_flow_set_to_64_user(struct dn_flow_set *set, struct dn_flow_set_64 *fs_bp)
{
	fs_bp->fs_nr = set->fs_nr;
	fs_bp->flags_fs = set->flags_fs;
	fs_bp->parent_nr = set->parent_nr;
	fs_bp->weight = set->weight;
	fs_bp->qsize = set->qsize;
	fs_bp->plr = set->plr;
	fs_bp->flow_mask = set->flow_mask;
	fs_bp->rq_size = set->rq_size;
	fs_bp->rq_elements = set->rq_elements;
	fs_bp->last_expired = set->last_expired;
	fs_bp->backlogged = set->backlogged;
	fs_bp->w_q = set->w_q;
	fs_bp->max_th = set->max_th;
	fs_bp->min_th = set->min_th;
	fs_bp->max_p = set->max_p;
	fs_bp->c_1 = set->c_1;
	fs_bp->c_2 = set->c_2;
	fs_bp->c_3 = set->c_3;
	fs_bp->c_4 = set->c_4;
	fs_bp->w_q_lookup = CAST_DOWN(user64_addr_t, VM_KERNEL_ADDRHIDE(set->w_q_lookup));
	fs_bp->lookup_depth = set->lookup_depth;
	fs_bp->lookup_step = set->lookup_step;
	fs_bp->lookup_weight = set->lookup_weight;
	fs_bp->avg_pkt_size = set->avg_pkt_size;
	fs_bp->max_pkt_size = set->max_pkt_size;
}

static
void
cp_queue_to_32_user( struct dn_flow_queue *q, struct dn_flow_queue_32 *qp)
{
	qp->id = q->id;
	qp->len = q->len;
	qp->len_bytes = q->len_bytes;
	qp->numbytes = q->numbytes;
	qp->tot_pkts = q->tot_pkts;
	qp->tot_bytes = q->tot_bytes;
	qp->drops = q->drops;
	qp->hash_slot = q->hash_slot;
	qp->avg = q->avg;
	qp->count = q->count;
	qp->random = q->random;
	qp->q_time = (u_int32_t)q->q_time;
	qp->heap_pos = q->heap_pos;
	qp->sched_time = q->sched_time;
	qp->S = q->S;
	qp->F = q->F;
}

static
void
cp_queue_to_64_user( struct dn_flow_queue *q, struct dn_flow_queue_64 *qp)
{
	qp->id = q->id;
	qp->len = q->len;
	qp->len_bytes = q->len_bytes;
	qp->numbytes = q->numbytes;
	qp->tot_pkts = q->tot_pkts;
	qp->tot_bytes = q->tot_bytes;
	qp->drops = q->drops;
	qp->hash_slot = q->hash_slot;
	qp->avg = q->avg;
	qp->count = q->count;
	qp->random = q->random;
	qp->q_time = (u_int32_t)q->q_time;
	qp->heap_pos = q->heap_pos;
	qp->sched_time = q->sched_time;
	qp->S = q->S;
	qp->F = q->F;
}

static
char *
cp_pipe_to_32_user(struct dn_pipe *p, char *bp0 __ended_by(bp_end), char *bp_end)
{
	struct dn_pipe_32 *pipe_bp = NULL; /* Pipe header */
	caddr_t bp; /* Pointer after the pipe header */

	/* Check for overflow, and assign `pipe_bp' and `bp' pointers, if safe */
	if (bp_end - bp0 < sizeof(*pipe_bp)) {
		/* Will overflow, can not proceed */
		return NULL;
	}
	pipe_bp = __unsafe_forge_single(struct dn_pipe_32 *, bp0);
	bp = bp0 + sizeof(*pipe_bp);

	pipe_bp->pipe_nr = p->pipe_nr;
	pipe_bp->bandwidth = p->bandwidth;
	pipe_bp->delay = p->delay;
	bcopy( &(p->scheduler_heap), &(pipe_bp->scheduler_heap), sizeof(struct dn_heap_32));
	pipe_bp->scheduler_heap.p = CAST_DOWN_EXPLICIT(user32_addr_t, VM_KERNEL_ADDRHIDE(pipe_bp->scheduler_heap.p));
	bcopy( &(p->not_eligible_heap), &(pipe_bp->not_eligible_heap), sizeof(struct dn_heap_32));
	pipe_bp->not_eligible_heap.p = CAST_DOWN_EXPLICIT(user32_addr_t, VM_KERNEL_ADDRHIDE(pipe_bp->not_eligible_heap.p));
	bcopy( &(p->idle_heap), &(pipe_bp->idle_heap), sizeof(struct dn_heap_32));
	pipe_bp->idle_heap.p = CAST_DOWN_EXPLICIT(user32_addr_t, VM_KERNEL_ADDRHIDE(pipe_bp->idle_heap.p));
	pipe_bp->V = p->V;
	pipe_bp->sum = p->sum;
	pipe_bp->numbytes = p->numbytes;
	pipe_bp->sched_time = p->sched_time;
	bcopy( p->if_name, pipe_bp->if_name, IFNAMSIZ);
	pipe_bp->ifp = CAST_DOWN_EXPLICIT(user32_addr_t, VM_KERNEL_ADDRHIDE(p->ifp));
	pipe_bp->ready = p->ready;

	cp_flow_set_to_32_user( &(p->fs), &(pipe_bp->fs));

	pipe_bp->delay = (pipe_bp->delay * 1000) / (hz * 10);
	/*
	 * 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 = CAST_DOWN_EXPLICIT( user32_addr_t, DN_IS_PIPE );
	/* clean pointers */
	pipe_bp->head = pipe_bp->tail = (user32_addr_t) 0;
	pipe_bp->fs.next = (user32_addr_t)0;
	pipe_bp->fs.pipe = (user32_addr_t)0;
	pipe_bp->fs.rq = (user32_addr_t)0;
	return dn_copy_set_32( &(p->fs), bp, bp_end);
}

/*
 * Returns NULL on error.
 */
static
char *
cp_pipe_to_64_user(struct dn_pipe *p, char *bp0 __ended_by(bp_end), char *bp_end)
{
	struct dn_pipe_64 *pipe_bp = NULL; /* Pipe header */
	caddr_t bp; /* Pointer after the pipe header */

	/* Check for overflow, and assign `pipe_bp' and `bp' pointers, if safe */
	if (bp_end - bp0 < sizeof(*pipe_bp)) {
		IP_DN_DBG_LOG("Would overflow: available=%ld", bp_end - bp0);
		/* Will overflow, can not proceed */
		return NULL;
	}
	pipe_bp = __unsafe_forge_single(struct dn_pipe_64 *, bp0);
	bp = bp0 + sizeof(*pipe_bp);

	/* Populate the pipe header */
	pipe_bp->pipe_nr = p->pipe_nr;
	pipe_bp->bandwidth = p->bandwidth;
	pipe_bp->delay = p->delay;
	bcopy( &(p->scheduler_heap), &(pipe_bp->scheduler_heap), sizeof(struct dn_heap_64));
	pipe_bp->scheduler_heap.p = CAST_DOWN(user64_addr_t, VM_KERNEL_ADDRHIDE(pipe_bp->scheduler_heap.p));
	bcopy( &(p->not_eligible_heap), &(pipe_bp->not_eligible_heap), sizeof(struct dn_heap_64));
	pipe_bp->not_eligible_heap.p = CAST_DOWN(user64_addr_t, VM_KERNEL_ADDRHIDE(pipe_bp->not_eligible_heap.p));
	bcopy( &(p->idle_heap), &(pipe_bp->idle_heap), sizeof(struct dn_heap_64));
	pipe_bp->idle_heap.p = CAST_DOWN(user64_addr_t, VM_KERNEL_ADDRHIDE(pipe_bp->idle_heap.p));
	pipe_bp->V = p->V;
	pipe_bp->sum = p->sum;
	pipe_bp->numbytes = p->numbytes;
	pipe_bp->sched_time = p->sched_time;
	bcopy( p->if_name, pipe_bp->if_name, IFNAMSIZ);
	pipe_bp->ifp = CAST_DOWN(user64_addr_t, VM_KERNEL_ADDRHIDE(p->ifp));
	pipe_bp->ready = p->ready;

	cp_flow_set_to_64_user( &(p->fs), &(pipe_bp->fs));

	pipe_bp->delay = (pipe_bp->delay * 1000) / (hz * 10);
	/*
	 * 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 = CAST_DOWN( user64_addr_t, DN_IS_PIPE );
	/* clean pointers */
	pipe_bp->head = pipe_bp->tail = USER_ADDR_NULL;
	pipe_bp->fs.next = USER_ADDR_NULL;
	pipe_bp->fs.pipe = USER_ADDR_NULL;
	pipe_bp->fs.rq = USER_ADDR_NULL;
	return dn_copy_set_64( &(p->fs), bp, bp_end);
}

static int
heap_init(struct dn_heap *h, int new_size)
{
	struct dn_heap_entry *p;

	if (h->size >= new_size) {
		printf("dummynet: heap_init, Bogus call, have %d want %d\n",
		    h->size, new_size);
		return 0;
	}
	new_size = (new_size + HEAP_INCREMENT) & ~HEAP_INCREMENT;
	p = krealloc_type(struct dn_heap_entry, h->size, new_size,
	    h->p, Z_NOWAIT | Z_ZERO);
	if (p == NULL) {
		printf("dummynet: heap_init, resize %d failed\n", new_size );
		return ENOMEM; /* error */
	}
	h->p = p;
	h->size = new_size;
	return 0;
}

/*
 * Routines to safely manage node offsets.
 *
 * If `heap->offset' > 0, the offset of the node in the heap
 * is also stored in the heap entries at the given offset.
 *
 * Otherwise, the heap entries do not contain heap offsets.
 */
static inline void
dn_heap_update_node_offset(struct dn_heap *heap, int node, int pos)
{
	caddr_t offset_ptr, obj_bytes;
	struct dn_heap_entry *ent;

	if (heap->offset <= 0) {
		/* Heap entries don't contain offsets, nothing to do. */
		return;
	}
	VERIFY(heap->size <= node);
	ent = &(heap->p[node]);
	VERIFY(heap->offset + sizeof(int) <= ent->obj_size);
	obj_bytes = ent->object;
	offset_ptr = obj_bytes + heap->offset;

	memcpy(offset_ptr, &pos, sizeof(int));
}

#define DN_INVALID_OFFSET (-1)

static inline int
dn_heap_get_node_offset(struct dn_heap *heap, char *obj_bytes __sized_by(obj_size), size_t obj_size)
{
	int obj_offset;
	caddr_t offset_ptr;
	if (heap->offset <= 0) {
		/* Heap entries don't contain offsets, nothing to do. */
		os_log(OS_LOG_DEFAULT,
		    "dummynet: dn_heap_get_node_offset from middle not supported on this heap!!!");
		return DN_INVALID_OFFSET;
	}
	VERIFY(heap->offset + sizeof(int) <= obj_size);
	offset_ptr = obj_bytes + heap->offset;
	memcpy(&obj_offset, offset_ptr, sizeof(int));
	if (obj_offset < 0 || obj_offset >= heap->elements) {
		printf("dummynet: dn_heap_get_node_offset, offset %d out of bound 0..%d\n",
		    obj_offset, heap->elements);
		return DN_INVALID_OFFSET;
	}
	return obj_offset;
}

#define GET_OFFSET(heap, obj, obj_size) dn_heap_get_node_offset((heap), (obj), (obj_size))

#define SET_OFFSET(heap, node) dn_heap_update_node_offset((heap), (node), (node))

/*
 * RESET_OFFSET is used for sanity checks. It sets offset to an invalid value.
 */
#define RESET_OFFSET(heap, node) dn_heap_update_node_offset((heap), (node), DN_INVALID_OFFSET)

/*
 * 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.
 */
static int
heap_insert(struct dn_heap *h, dn_key key1, void *__sized_by_or_null(obj_size)object, size_t obj_size)
{
	int son = h->elements;

	if (object == NULL) { /* data already there, set starting point */
		VERIFY(key1 < INT_MAX);
		son = (int)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 = object;
		h->p[son].obj_size = obj_size;
		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 *__sized_by_or_null(obj_size)obj, size_t obj_size)
{
	int child, father, maxelt = h->elements - 1;

	if (maxelt < 0) {
		printf("dummynet: warning, extract from empty heap 0x%llx\n",
		    (uint64_t)VM_KERNEL_ADDRPERM(h));
		return;
	}
	father = 0; /* default: move up smallest child */
	if (obj != NULL) { /* extract specific element, index is at offset */
		father = GET_OFFSET(h, obj, obj_size);
		if (father == DN_INVALID_OFFSET) {
			panic("dummynet: heap_extract");
		}
	}
	RESET_OFFSET(h, father);
	child = HEAP_LEFT(father);      /* left child */
	while (child <= maxelt) {       /* valid entry */
		if (child != maxelt && 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 != maxelt) {
		/*
		 * Fill hole with last entry and bubble up, reusing the insert code
		 */
		h->p[father] = h->p[maxelt];
		heap_insert(h, father, NULL, 0); /* this one cannot fail */
	}
}

/*
 * 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, 0);
	}
}

/*
 * cleanup the heap and free data structure
 */
static void
heap_free(struct dn_heap *h)
{
	kfree_type_counted_by(struct dn_heap_entry, h->size, h->p);
	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);

	if (!(mtag != NULL &&
	    mtag->m_tag_id == KERNEL_MODULE_TAG_ID &&
	    mtag->m_tag_type == KERNEL_TAG_TYPE_DUMMYNET &&
	    sizeof(struct dn_pkt_tag) <= mtag->m_tag_len)) {
		panic("packet on dummynet queue w/o dummynet tag: 0x%llx",
		    (uint64_t)VM_KERNEL_ADDRPERM(m));
	}

	return (struct dn_pkt_tag *)(mtag->m_tag_data);
}

/*
 * 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 = NULL;
	u_int64_t schedule_time;

	LCK_MTX_ASSERT(&dn_mutex, LCK_MTX_ASSERT_OWNED);
	ASSERT(serialize >= 0);
	if (serialize == 0) {
		while ((m = pipe->head) != NULL) {
			pkt = dn_tag_get(m);
			if (!DN_KEY_LEQ(pkt->dn_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;
		}
	}

	schedule_time = pkt == NULL || DN_KEY_LEQ(pkt->dn_output_time, curr_time) ?
	    curr_time + 1 : pkt->dn_output_time;

	/* if there are leftover packets, put the pipe into the heap for next ready 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, schedule_time, pipe, sizeof(struct dn_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)
 */

/* hz is 100, which gives a granularity of 10ms in the old timer.
 * The timer has been changed to fire every 1ms, so the use of
 * hz has been modified here. All instances of hz have been left
 * in place but adjusted by a factor of 10 so that hz is functionally
 * equal to 1000.
 */
#define SET_TICKS(_m, q, p)     \
    ((_m)->m_pkthdr.len*8*(hz*10) - (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->dn_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;

	LCK_MTX_ASSERT(&dn_mutex, LCK_MTX_ASSERT_OWNED);

	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 * 10) : 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, q, sizeof(struct dn_flow_queue));
		/* 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, 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);
	int64_t p_numbytes = p->numbytes;

	LCK_MTX_ASSERT(&dn_mutex, LCK_MTX_ASSERT_OWNED);

	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 && !IFCQ_IS_EMPTY(p->ifp->if_snd)) {
			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_int32_t len = pkt->m_pkthdr.len;
			u_int64_t len_scaled = p->bandwidth ? len * 8 * (hz * 10) : 0;

			heap_extract(sch, NULL, 0); /* 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, sizeof(struct dn_flow_queue));
			} 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, sizeof(struct dn_flow_queue));
				} else {
					heap_insert(sch, q->F, q, sizeof(struct dn_flow_queue));
				}
			}
		}
		/*
		 * 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, 0);
			heap_insert(sch, q->F, q, sizeof(struct dn_flow_queue));
		}

		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)->dn_output_time += t;
		p->sched_time = curr_time;
		heap_insert(&wfq_ready_heap, curr_time + t, p, sizeof(struct dn_pipe));
		/* XXX should check errors on heap_insert, and drain the whole
		 * queue on error hoping next time we are luckier.
		 */
	}

	/* Fit (adjust if necessary) 64bit result into 32bit variable. */
	if (p_numbytes > INT_MAX) {
		p->numbytes = INT_MAX;
	} else if (p_numbytes < INT_MIN) {
		p->numbytes = INT_MIN;
	} else {
		p->numbytes = (int)p_numbytes;
	}

	/*
	 * 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, head, tail);
	}
}

/*
 * This is called every 1ms. It is used to
 * increment the current tick counter and schedule expired events.
 */
static void
dummynet(__unused void * unused)
{
	void *p; /* generic parameter to handler */
	struct dn_heap *h;
	struct dn_heap *heaps[3];
	struct mbuf * __single head = NULL, * __single tail = NULL;
	int i;
	struct dn_pipe *pe;
	struct timespec ts;
	struct timeval      tv;

	heaps[0] = &ready_heap;         /* fixed-rate queues */
	heaps[1] = &wfq_ready_heap;     /* wfq queues */
	heaps[2] = &extract_heap;       /* delay line */

	lck_mtx_lock(&dn_mutex);

	/* make all time measurements in milliseconds (ms) -
	 * here we convert secs and usecs to msecs (just divide the
	 * usecs and take the closest whole number).
	 */
	microuptime(&tv);
	curr_time = (tv.tv_sec * 1000) + (tv.tv_usec / 1000);

	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, 0); /* need to extract before processing */
			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(pe, &pipehash[i], 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, 0);
				q->S = q->F + 1; /* mark timestamp as invalid */
				pe->sum -= q->fs->weight;
			}
		}
	}

	/* check the heaps to see if there's still stuff in there, and
	 * only set the timer if there are packets to process
	 */
	timer_enabled = 0;
	for (i = 0; i < 3; i++) {
		h = heaps[i];
		if (h->elements > 0) { // set the timer
			ts.tv_sec = 0;
			ts.tv_nsec = 1 * 1000000;       // 1ms
			timer_enabled = 1;
			bsd_timeout(dummynet, NULL, &ts);
			break;
		}
	}

	if (head != NULL) {
		serialize++;
	}

	lck_mtx_unlock(&dn_mutex);

	/* Send out the de-queued list of ready-to-send packets */
	if (head != NULL) {
		dummynet_send(head);
		lck_mtx_lock(&dn_mutex);
		serialize--;
		lck_mtx_unlock(&dn_mutex);
	}
}


static void
dummynet_send(struct mbuf *m)
{
	struct dn_pkt_tag *pkt;
	struct mbuf *n;

	for (; m != NULL; m = n) {
		n = m->m_nextpkt;
		m->m_nextpkt = NULL;
		pkt = dn_tag_get(m);

		DPRINTF(("dummynet_send m: 0x%llx dn_dir: %d dn_flags: 0x%x\n",
		    (uint64_t)VM_KERNEL_ADDRPERM(m), pkt->dn_dir,
		    pkt->dn_flags));

		switch (pkt->dn_dir) {
		case DN_TO_IP_OUT: {
			struct route tmp_rt;

			/* route is already in the packet's dn_ro */
			bzero(&tmp_rt, sizeof(tmp_rt));

			/* Force IP_RAWOUTPUT as the IP header is fully formed */
			pkt->dn_flags |= IP_RAWOUTPUT | IP_FORWARDING;
			(void)ip_output(m, NULL, &tmp_rt, pkt->dn_flags, NULL, NULL);
			ROUTE_RELEASE(&tmp_rt);
			break;
		}
		case DN_TO_IP_IN:
			proto_inject(PF_INET, m);
			break;
		case DN_TO_IP6_OUT: {
			/* routes already in the packet's dn_{ro6,pmtu} */
			if (pkt->dn_origifp != NULL) {
				ip6_output_setsrcifscope(m, pkt->dn_origifp->if_index, NULL);
				ip6_output_setdstifscope(m, pkt->dn_origifp->if_index, NULL);
			} else {
				ip6_output_setsrcifscope(m, IFSCOPE_UNKNOWN, NULL);
				ip6_output_setdstifscope(m, IFSCOPE_UNKNOWN, NULL);
			}

			ip6_output(m, NULL, NULL, IPV6_FORWARDING, NULL, NULL, NULL);
			break;
		}
		case DN_TO_IP6_IN:
			proto_inject(PF_INET6, 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;
	struct timeval timenow;

	/* reviewed for getmicrotime usage */
	getmicrotime(&timenow);

	if (fs->last_expired == timenow.tv_sec) {
		return 0;
	}
	fs->last_expired = (int)timenow.tv_sec;
	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--;
				kfree_type(struct dn_flow_queue, old_q);
			}
		}
	}
	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 = kalloc_type(struct dn_flow_queue, Z_NOWAIT | Z_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 ip_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--;
				kfree_type(struct dn_flow_queue, old_q);
				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_int64_t 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 = (my_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 = (my_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,
 *		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 mbuf *__single head = NULL, *__single tail = NULL;
	struct dn_pkt_tag *pkt;
	struct m_tag *mtag;
	struct dn_flow_set *fs = NULL;
	struct dn_pipe *pipe;
	u_int32_t len = m->m_pkthdr.len;
	struct dn_flow_queue *q = NULL;
	int is_pipe = 0;
	struct timespec ts;
	struct timeval      tv;

	DPRINTF(("dummynet_io m: 0x%llx pipe: %d dir: %d\n",
	    (uint64_t)VM_KERNEL_ADDRPERM(m), pipe_nr, dir));


#if DUMMYNET
	is_pipe = fwa->fwa_flags == DN_IS_PIPE ? 1 : 0;
#endif /* DUMMYNET */

	pipe_nr &= 0xffff;

	lck_mtx_lock(&dn_mutex);

	/* make all time measurements in milliseconds (ms) -
	 * here we convert secs and usecs to msecs (just divide the
	 * usecs and take the closest whole number).
	 */
	microuptime(&tv);
	curr_time = (tv.tv_sec * 1000) + (tv.tv_usec / 1000);

	/*
	 * This is a dummynet rule, so we expect an O_PIPE or O_QUEUE rule.
	 */
	if (is_pipe) {
		pipe = locate_pipe(pipe_nr);
		if (pipe != NULL) {
			fs = &(pipe->fs);
		}
	} else {
		fs = locate_flowset(pipe_nr);
	}


	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->fwa_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 && (my_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_create(KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_DUMMYNET,
	    sizeof(struct dn_pkt_tag), M_NOWAIT, m);
	if (mtag == NULL) {
		goto dropit;            /* cannot allocate packet header	*/
	}
	m_tag_prepend(m, mtag); /* attach to mbuf chain */

	pkt = (struct dn_pkt_tag *)(mtag->m_tag_data);
	bzero(pkt, sizeof(struct dn_pkt_tag));
	/* ok, i can handle the pkt now... */
	/* build and enqueue packet + parameters */
	pkt->dn_pf_rule = fwa->fwa_pf_rule;
	pkt->dn_dir = dir;

	pkt->dn_ifp = fwa->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.
		 */
		if (fwa->fwa_ro) {
			route_copyout(&pkt->dn_ro, fwa->fwa_ro, sizeof(pkt->dn_ro));
		}
		if (fwa->fwa_dst) {
			if (fwa->fwa_dst == SIN(&fwa->fwa_ro->ro_dst)) { /* dst points into ro */
				fwa->fwa_dst = SIN(&(pkt->dn_ro.ro_dst));
			}

			SOCKADDR_COPY(fwa->fwa_dst, &pkt->dn_dst, sizeof(pkt->dn_dst));
		}
	} else if (dir == DN_TO_IP6_OUT) {
		if (fwa->fwa_ro6) {
			route_copyout((struct route *)&pkt->dn_ro6,
			    (struct route *)fwa->fwa_ro6, sizeof(pkt->dn_ro6));
		}
		if (fwa->fwa_ro6_pmtu) {
			route_copyout((struct route *)&pkt->dn_ro6_pmtu,
			    (struct route *)fwa->fwa_ro6_pmtu, sizeof(pkt->dn_ro6_pmtu));
		}
		if (fwa->fwa_dst6) {
			if (fwa->fwa_dst6 == SIN6(&fwa->fwa_ro6->ro_dst)) { /* dst points into ro */
				fwa->fwa_dst6 = SIN6(&(pkt->dn_ro6.ro_dst));
			}

			SOCKADDR_COPY(fwa->fwa_dst6, &pkt->dn_dst6, sizeof(pkt->dn_dst6));
		}
		pkt->dn_origifp = fwa->fwa_origifp;
		pkt->dn_mtu = fwa->fwa_mtu;
		pkt->dn_unfragpartlen = fwa->fwa_unfragpartlen;
		if (fwa->fwa_exthdrs) {
			bcopy(fwa->fwa_exthdrs, &pkt->dn_exthdrs, sizeof(pkt->dn_exthdrs));
			/*
			 * Need to zero out the source structure so the mbufs
			 * won't be freed by ip6_output()
			 */
			bzero(fwa->fwa_exthdrs, sizeof(struct ip6_exthdrs));
		}
	}
	if (dir == DN_TO_IP_OUT || dir == DN_TO_IP6_OUT) {
		pkt->dn_flags = fwa->fwa_oflags;
		if (fwa->fwa_ipoa != NULL) {
			pkt->dn_ipoa = *(fwa->fwa_ipoa);
		}
	}
	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, sizeof(struct dn_flow_queue));
		}
	} 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, sizeof(struct dn_flow_queue));
			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, sizeof(struct dn_flow_queue));
		} else {
			heap_insert(&(pipe->scheduler_heap), q->F, q, sizeof(struct dn_flow_queue));
			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:
	/* start the timer and set global if not already set */
	if (!timer_enabled) {
		ts.tv_sec = 0;
		ts.tv_nsec = 1 * 1000000;       // 1ms
		timer_enabled = 1;
		bsd_timeout(dummynet, NULL, &ts);
	}

	lck_mtx_unlock(&dn_mutex);

	if (head != NULL) {
		dummynet_send(head);
	}

	return 0;

dropit:
	if (q) {
		q->drops++;
	}
	lck_mtx_unlock(&dn_mutex);
	m_freem(m);
	return (fs && (fs->flags_fs & DN_NOERROR)) ? 0 : ENOBUFS;
}

/*
 * Below, the ROUTE_RELEASE 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 {                                                  \
	struct m_tag *tag = m_tag_locate(                                         \
	    (_m), KERNEL_MODULE_TAG_ID, KERNEL_TAG_TYPE_DUMMYNET);                \
	if (tag) {                                                                \
	    VERIFY(sizeof(struct dn_pkt_tag) <= tag->m_tag_len);                  \
	    struct dn_pkt_tag *n = (struct dn_pkt_tag *)(tag->m_tag_data);        \
	    ROUTE_RELEASE(&n->dn_ro);                                             \
	}                                                                         \
	m_tag_delete((_m), tag);                                                  \
	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;

	LCK_MTX_ASSERT(&dn_mutex, LCK_MTX_ASSERT_OWNED);

	for (i = 0; i <= fs->rq_size; i++) {
		for (q = fs->rq[i]; q; q = qn) {
			struct mbuf *m, *mnext;

			mnext = q->head;
			while ((m = mnext) != NULL) {
				mnext = m->m_nextpkt;
				DN_FREE_PKT(m);
			}
			qn = q->next;
			kfree_type(struct dn_flow_queue, q);
		}
		fs->rq[i] = NULL;
	}
	fs->rq_elements = 0;
	if (all) {
		/* RED - free lookup table */
		if (fs->w_q_lookup) {
			kfree_data_counted_by(fs->w_q_lookup, fs->lookup_depth);
		}
		/*
		 * Can not use `kfree_type_counted_by' `for fs->rq',
		 * because the latter is counted by `fs->rq_size + 1'
		 */
		struct dn_flow_queue ** rq = fs->rq;
		kfree_type(struct dn_flow_queue *, fs->rq_size + 1, rq);
		fs->rq = NULL;
		fs->rq_size = 0;
		/* if this fs is not part of a pipe, free it */
		if (fs->pipe && fs != &(fs->pipe->fs)) {
			kfree_type(struct dn_flow_set, fs);
		}
	}
}

/*
 * 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.
 */
static void
dummynet_flush(void)
{
	struct dn_pipe *pipe, *pipe1;
	struct dn_flow_set *fs, *fs1;
	int i;

	lck_mtx_lock(&dn_mutex);


	/* 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);
			kfree_type(struct dn_pipe, pipe);
		}
	}
	lck_mtx_unlock(&dn_mutex);
}

/*
 * 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) {
		kfree_data_counted_by(x->w_q_lookup, x->lookup_depth);
	}
	if (red_lookup_depth == 0) {
		printf("\ndummynet: net.inet.ip.dummynet.red_lookup_depth must be > 0\n");
		return EINVAL;
	}
	x->w_q_lookup = (u_int *) kalloc_data(red_lookup_depth * sizeof(int),
	    Z_WAITOK | Z_ZERO);
	x->lookup_depth = red_lookup_depth;
	if (x->w_q_lookup == NULL) {
		printf("dummynet: sorry, cannot allocate red lookup table\n");
		return ENOMEM;
	}

	/* 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 = kalloc_type(struct dn_flow_queue *, l + 1,
		    Z_NOWAIT | Z_ZERO);
		x->rq_size = l;
	} else {            /* one is enough for null mask */
		x->rq = kalloc_type(struct dn_flow_queue *, 1 + 1,
		    Z_NOWAIT | Z_ZERO);
		x->rq_size = 1;
	}

	if (x->rq == NULL) {
		printf("dummynet: sorry, cannot allocate queue\n");
		return ENOMEM;
	}
	x->rq_elements = 0;
	return 0;
}

static int
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) {
		return config_red(src, x); /* XXX should check errors */
	}
	return 0;
}

/*
 * 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;
	bool is_new = false;

	/*
	 * 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 * 10)) / 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, *b;
		struct dummynet_event dn_event;
		lck_mtx_lock(&dn_mutex);

		/* locate pipe */
		b = locate_pipe(p->pipe_nr);

		if (b == NULL || b->pipe_nr != p->pipe_nr) { /* new pipe */
			is_new = true;
			x = kalloc_type(struct dn_pipe, Z_WAITOK | Z_ZERO);
			if (x == NULL) {
				lck_mtx_unlock(&dn_mutex);
				printf("dummynet: no memory for new pipe\n");
				return ENOMEM;
			}
			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.p = NULL;
			x->idle_heap.size = x->idle_heap.elements = 0;
			x->idle_heap.offset = offsetof(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;
		r = set_fs_parms(&(x->fs), pfs);
		if (r != 0) {
			lck_mtx_unlock(&dn_mutex);
			if (is_new) { /* a new pipe */
				kfree_type(struct dn_pipe, x);
			}
			return r;
		}

		if (x->fs.rq == NULL) { /* a new pipe */
			r = alloc_hash(&(x->fs), pfs);
			if (r) {
				lck_mtx_unlock(&dn_mutex);
				if (is_new) {
					kfree_type(struct dn_pipe, x);
				}
				return r;
			}
			SLIST_INSERT_HEAD(&pipehash[HASH(x->pipe_nr)],
			    x, next);
		}
		lck_mtx_unlock(&dn_mutex);

		bzero(&dn_event, sizeof(dn_event));
		dn_event.dn_event_code = DUMMYNET_PIPE_CONFIG;
		dn_event.dn_event_pipe_config.bandwidth = p->bandwidth;
		dn_event.dn_event_pipe_config.delay = p->delay;
		dn_event.dn_event_pipe_config.plr = pfs->plr;

		dummynet_event_enqueue_nwk_wq_entry(&dn_event);
	} else { /* config queue */
		struct dn_flow_set *x, *b;

		lck_mtx_lock(&dn_mutex);
		/* locate flow_set */
		b = locate_flowset(pfs->fs_nr);

		if (b == NULL || b->fs_nr != pfs->fs_nr) { /* new  */
			is_new = true;
			if (pfs->parent_nr == 0) { /* need link to a pipe */
				lck_mtx_unlock(&dn_mutex);
				return EINVAL;
			}
			x = kalloc_type(struct dn_flow_set, Z_WAITOK | Z_ZERO);
			if (x == NULL) {
				lck_mtx_unlock(&dn_mutex);
				printf("dummynet: no memory for new flow_set\n");
				return ENOMEM;
			}
			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) {
				lck_mtx_unlock(&dn_mutex);
				return EINVAL;
			}
			x = b;
		}
		r = set_fs_parms(x, pfs);
		if (r != 0) {
			lck_mtx_unlock(&dn_mutex);
			printf("dummynet: no memory for new flow_set\n");
			if (is_new) {
				kfree_type(struct dn_flow_set, x);
			}
			return r;
		}

		if (x->rq == NULL) { /* a new flow_set */
			r = alloc_hash(x, pfs);
			if (r) {
				lck_mtx_unlock(&dn_mutex);
				kfree_type(struct dn_flow_set, x);
				return r;
			}
			SLIST_INSERT_HEAD(&flowsethash[HASH(x->fs_nr)],
			    x, next);
		}
		lck_mtx_unlock(&dn_mutex);
	}
	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 *p;
	struct mbuf *m, *mnext;
	int i;

	LCK_MTX_ASSERT(&dn_mutex, LCK_MTX_ASSERT_OWNED);

	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(p, &pipehash[i], next) {
			purge_flow_set(&(p->fs), 0);

			mnext = p->head;
			while ((m = mnext) != NULL) {
				mnext = m->m_nextpkt;
				DN_FREE_PKT(m);
			}
			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 *b;
		struct dn_flow_set *fs;
		int i;

		lck_mtx_lock(&dn_mutex);
		/* locate pipe */
		b = locate_pipe(p->pipe_nr);
		if (b == NULL) {
			lck_mtx_unlock(&dn_mutex);
			return EINVAL; /* not found */
		}

		/* Unlink from list of pipes. */
		SLIST_REMOVE(&pipehash[HASH(b->pipe_nr)], b, 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 == 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);
		lck_mtx_unlock(&dn_mutex);

		kfree_type(struct dn_pipe, b);
	} else { /* this is a WF2Q queue (dn_flow_set) */
		struct dn_flow_set *b;

		lck_mtx_lock(&dn_mutex);
		/* locate set */
		b = locate_flowset(p->fs.fs_nr);
		if (b == NULL) {
			lck_mtx_unlock(&dn_mutex);
			return EINVAL; /* not found */
		}


		/* Unlink from list of flowsets. */
		SLIST_REMOVE( &flowsethash[HASH(b->fs_nr)], b, dn_flow_set, next);

		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);
		lck_mtx_unlock(&dn_mutex);
	}
	return 0;
}

/*
 * helper function used to copy data from kernel in DUMMYNET_GET
 */
static
char*
dn_copy_set_32(struct dn_flow_set *set, char *bp __ended_by(bp_end), char *bp_end)
{
	int i, copied = 0, overflow = 0;
	struct dn_flow_queue *q;
	struct dn_flow_queue_32 *qp;
	caddr_t bp_inner = bp;

	IP_DN_DBG_LOG("Asked to copy set_32: available=%ld, required=%lu",
	    bp_end - bp_inner, sizeof(*qp));
	if (bp_end - bp_inner < sizeof(*qp)) {
		IP_DN_DBG_LOG("Insufficient space to copy: available=%ld, required=%lu",
		    bp_end - bp_inner, sizeof(*qp));
		return NULL;
	}

	LCK_MTX_ASSERT(&dn_mutex, LCK_MTX_ASSERT_OWNED);

	for (i = 0; i <= set->rq_size && !overflow; i++) {
		for (q = set->rq[i]; q && !overflow; q = q->next) {
			/* Check for overflow before attempting to write to `bp_inner' */
			if (bp_end - bp_inner < sizeof(*qp)) {
				os_log_error(OS_LOG_DEFAULT,
				    "Stoping flow set copy after %d elements to avoid overflow; "
				    "mem: available=%lu, required=%lu", copied, bp_end - bp_inner, sizeof(*qp));
				overflow = 1;
				break;
			}

			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 0x%llx, should be 0x%llx)\n", i,
				    (uint64_t)VM_KERNEL_ADDRPERM(q->fs),
				    (uint64_t)VM_KERNEL_ADDRPERM(set));
			}
			copied++;
			qp = (struct dn_flow_queue_32 *)(void *)bp_inner;
			bp_inner += sizeof(*qp);
			IP_DN_DBG_LOG("Advancing bp_inner old=0x%llx new=0x%llx end=0x%llx available=%lu",
			    (uint64_t)VM_KERNEL_ADDRPERM(qp),
			    (uint64_t)VM_KERNEL_ADDRPERM(bp_inner),
			    (uint64_t)VM_KERNEL_ADDRPERM(bp_end),
			    bp_end - bp_inner);
			cp_queue_to_32_user( q, qp );
			/* cleanup pointers */
			qp->next = (user32_addr_t)0;
			qp->head = qp->tail = (user32_addr_t)0;
			qp->fs = (user32_addr_t)0;
		}
	}
	if (copied != set->rq_elements) {
		printf("dummynet: ++ wrong count, have %d should be %d\n",
		    copied, set->rq_elements);
	}
	return overflow ? NULL : bp_inner;
}

/*
 * Returns NULL on overflow.
 */
static
char*
dn_copy_set_64(struct dn_flow_set *set, char *bp __ended_by(bp_end), char *bp_end)
{
	int i, copied = 0, overflow = 0, total_required = 0;
	struct dn_flow_queue *q;
	struct dn_flow_queue_64 *qp;
	caddr_t bp_inner = bp;

	IP_DN_DBG_LOG("Asked to copy set_64: available=%ld", bp_end - bp_inner);
	if (bp_end - bp_inner < sizeof(*qp)) {
		IP_DN_DBG_LOG("Insufficient space to copy: available=%ld, required=%lu",
		    bp_end - bp_inner, sizeof(*qp));
		return NULL;
	}

	LCK_MTX_ASSERT(&dn_mutex, LCK_MTX_ASSERT_OWNED);

	for (i = 0; i <= set->rq_size && !overflow; i++) {
		for (q = set->rq[i]; q && !overflow; q = q->next) {
			IP_DN_DBG_LOG("Iter=%d to copied=%d available=%ld",
			    i, copied, bp_end - bp_inner);
			/* Check for overflow before attempting to write to `bp_inner' */
			if (bp_end - bp_inner < sizeof(*qp)) {
				os_log_error(OS_LOG_DEFAULT,
				    "Stoping flow set copy after %d elements to avoid overflow; "
				    "mem: available=%lu, required=%lu", copied, bp_end - bp_inner, sizeof(*qp));
				overflow = 1;
			}
			/* If overflow bit is set, continue the iteration only to count the total required memory */
			total_required += sizeof(*qp);
			if (overflow) {
				continue; /* to next q, we are only counting memory here. */
			}

			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 0x%llx, should be 0x%llx)\n", i,
				    (uint64_t)VM_KERNEL_ADDRPERM(q->fs),
				    (uint64_t)VM_KERNEL_ADDRPERM(set));
			}
			copied++;
			//bcopy(q, qp, sizeof(*q));
			qp = (struct dn_flow_queue_64 *)(void *)bp_inner;
			bp_inner += sizeof(*qp);
			IP_DN_DBG_LOG("Advancing bp_inner old=0x%llx new=0x%llx end=0x%llx available=%lu",
			    (uint64_t)VM_KERNEL_ADDRPERM(qp),
			    (uint64_t)VM_KERNEL_ADDRPERM(bp_inner),
			    (uint64_t)VM_KERNEL_ADDRPERM(bp_end),
			    bp_end - bp_inner);
			cp_queue_to_64_user( q, qp );
			/* cleanup pointers */
			qp->next = USER_ADDR_NULL;
			qp->head = qp->tail = USER_ADDR_NULL;
			qp->fs = USER_ADDR_NULL;
		}
	}
	if (copied != set->rq_elements) {
		printf("dummynet: ++ wrong count, have %d should be %d\n",
		    copied, set->rq_elements);
	}

	char * ret = overflow ? NULL : bp_inner;
	IP_DN_DBG_LOG("Returning 0x%llx overflow=%d bp=0x%llx bp_inner=0x%llx bp_end=0x%llx available=%ld total_required=%d total_available=%lu",
	    (uint64_t)VM_KERNEL_ADDRPERM(ret),
	    overflow,
	    (uint64_t)VM_KERNEL_ADDRPERM(bp),
	    (uint64_t)VM_KERNEL_ADDRPERM(bp_inner),
	    (uint64_t)VM_KERNEL_ADDRPERM(bp_end),
	    bp_end - bp_inner,
	    total_required,
	    bp_end - bp);
	return ret;
}

static size_t
dn_calc_size(int is64user)
{
	struct dn_flow_set *set;
	struct dn_pipe *p;
	size_t size = 0;
	size_t pipesize;
	size_t queuesize;
	size_t setsize;
	int i;

#if DUMMYNET_DEBUG
	unsigned pq_count = 0, pqe_count = 0;
	unsigned fsq_count = 0, fsqe_count = 0;
#endif /* DUMMYNET_DEBUG */

	LCK_MTX_ASSERT(&dn_mutex, LCK_MTX_ASSERT_OWNED);
	if (is64user) {
		pipesize = sizeof(struct dn_pipe_64);
		queuesize = sizeof(struct dn_flow_queue_64);
		setsize = sizeof(struct dn_flow_set_64);
	} else {
		pipesize = sizeof(struct dn_pipe_32);
		queuesize = sizeof(struct dn_flow_queue_32);
		setsize = sizeof(struct dn_flow_set_32);
	}
	/*
	 * compute size of data structures: list of pipes and flow_sets.
	 */
	for (i = 0; i < HASHSIZE; i++) {
		SLIST_FOREACH(p, &pipehash[i], next) {
#if DUMMYNET_DEBUG
			pq_count++;
			pqe_count += p->fs.rq_elements;
#endif /* DUMMYNET_DEBUG */
			size += sizeof(*p) +
			    p->fs.rq_elements * sizeof(struct dn_flow_queue);
		}
		SLIST_FOREACH(set, &flowsethash[i], next) {
#if DUMMYNET_DEBUG
			fsq_count++;
			fsqe_count += set->rq_elements;
#endif /* DUMMYNET_DEBUG */
			size += sizeof(*set) +
			    set->rq_elements * sizeof(struct dn_flow_queue);
		}
	}

#if DUMMYNET_DEBUG
	IP_DN_DBG_LOG("dn_size=%lu (pipe queues: count=%u elements=%u; flowset queues: count=%u elemnts=%u)",
	    size, pq_count, pqe_count, fsq_count, fsqe_count);
#endif /* DUMMYNET_DEBUG */

	return size;
}

static int
dummynet_get(struct sockopt *sopt)
{
	char *buf = NULL;
	char *bp_end = NULL; /* sentinel pointer */
	char *bp __ended_by(bp_end) = bp_end; /* "copy-pointer" */
	char *bp_next = NULL; /* next value for copy-pointer, may overflow */
	size_t size = 0;
	struct dn_flow_set *set;
	struct dn_pipe *p;
	int error = 0, i;
	int overflow = 0;
	int is64user = 0;

	/* XXX lock held too long */
	lck_mtx_lock(&dn_mutex);
	/*
	 * XXX: Ugly, but we need to allocate memory with M_WAITOK flag
	 * and we cannot use this flag while holding a mutex.
	 */
	if (proc_is64bit(sopt->sopt_p)) {
		is64user = 1;
	}
	for (i = 0; i < 10; i++) {
		size = dn_calc_size(is64user);
		lck_mtx_unlock(&dn_mutex);
		buf = kalloc_data(size, Z_WAITOK | Z_ZERO);
		if (buf == NULL) {
			return ENOMEM;
		}
		lck_mtx_lock(&dn_mutex);
		if (size == dn_calc_size(is64user)) {
			/*
			 * This check is necessary, because pipes/flowsets can change
			 * while we weren't holding the lock
			 */
			break;
		}
		kfree_data(buf, size);
		buf = NULL;
	}
	if (buf == NULL) {
		lck_mtx_unlock(&dn_mutex);
		return ENOMEM;
	}

	/* TODO: follow up why without this forge `bp' gets fishy bounds. */
	bp = __unsafe_forge_bidi_indexable(char *, buf, size);
	bp_end = buf + size;

	for (i = 0; i < HASHSIZE && !overflow; i++) {
		SLIST_FOREACH(p, &pipehash[i], next) {
			/*
			 * 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.
			 */
			if (is64user) {
				bp_next = cp_pipe_to_64_user(p, bp, bp_end);
			} else {
				bp_next = cp_pipe_to_32_user(p, bp, bp_end);
			}
			if (bp_next == NULL) {
				IP_DN_DBG_LOG("Overflow detected old=0x%llx end=0x%llx",
				    (uint64_t)VM_KERNEL_ADDRPERM(bp),
				    (uint64_t)VM_KERNEL_ADDRPERM(bp_end));
				overflow = 1;
				break;
			}
			IP_DN_DBG_LOG("advancing bp: old=0x%llx new=0x%llx end=0x%llx",
			    (uint64_t)VM_KERNEL_ADDRPERM(bp),
			    (uint64_t)VM_KERNEL_ADDRPERM(bp_next),
			    (uint64_t)VM_KERNEL_ADDRPERM(bp_end));
			bp = bp_next;
			bp_end = bp_end;
		}
	}

#if DUMMYNET_DEBUG
	if (overflow) {
		IP_DN_DBG_LOG("Overflow detected old=0x%llx end=0x%llx",
		    (uint64_t)VM_KERNEL_ADDRPERM(bp),
		    (uint64_t)VM_KERNEL_ADDRPERM(bp_end));
	}
#endif

	for (i = 0; i < HASHSIZE && !overflow; i++) {
		SLIST_FOREACH(set, &flowsethash[i], next) {
			struct dn_flow_set_64 *fs_bp;
			bp_next = bp + sizeof(*fs_bp);
			if (bp_end < bp_next) {
				IP_DN_DBG_LOG("Overflow detected old=0x%llx end=0x%llx available=%lu required=%lu",
				    (uint64_t)VM_KERNEL_ADDRPERM(bp),
				    (uint64_t)VM_KERNEL_ADDRPERM(bp_end),
				    bp_end - bp,
				    sizeof(*fs_bp));
				overflow = 1;
				break;
			}
			fs_bp = (struct dn_flow_set_64 *)(void *)bp;
			bp = bp_next;
			bp_end = bp_end;
			cp_flow_set_to_64_user(set, fs_bp);
			/* XXX same hack as above */
			fs_bp->next = CAST_DOWN(user64_addr_t,
			    DN_IS_QUEUE);
			fs_bp->pipe = USER_ADDR_NULL;
			fs_bp->rq = USER_ADDR_NULL;
			bp_next = dn_copy_set_64( set, bp, bp_end);
			if (bp_next == NULL) {
				overflow = 1;
				break;
			}
			bp = bp_next;
			bp_end = bp_end;
		}
	}
	lck_mtx_unlock(&dn_mutex);
	error = sooptcopyout(sopt, buf, size);
	kfree_data(buf, size);
	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 && securelevel >= 3) {
		return EPERM;
	}

	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;
		if (proc_is64bit(sopt->sopt_p)) {
			error = cp_pipe_from_user_64( sopt, p );
		} else {
			error = cp_pipe_from_user_32( sopt, p );
		}

		if (error) {
			break;
		}
		error = config_pipe(p);
		break;

	case IP_DUMMYNET_DEL:   /* remove a pipe or queue */
		p = &tmp_pipe;
		if (proc_is64bit(sopt->sopt_p)) {
			error = cp_pipe_from_user_64( sopt, p );
		} else {
			error = cp_pipe_from_user_32( sopt, p );
		}
		if (error) {
			break;
		}

		error = delete_pipe(p);
		break;
	}
	return error;
}

void
dummynet_init(void)
{
	eventhandler_lists_ctxt_init(&dummynet_evhdlr_ctxt);
}

void
ip_dn_init(void)
{
	/* setup locks */
	ready_heap.p = NULL;
	ready_heap.size = ready_heap.elements = 0;
	ready_heap.offset = 0;

	wfq_ready_heap.p = NULL;
	wfq_ready_heap.size = wfq_ready_heap.elements = 0;
	wfq_ready_heap.offset = 0;

	extract_heap.p = NULL;
	extract_heap.size = extract_heap.elements = 0;
	extract_heap.offset = 0;
	ip_dn_ctl_ptr = ip_dn_ctl;
	ip_dn_io_ptr = dummynet_io;
}

struct dn_event_nwk_wq_entry {
	struct nwk_wq_entry nwk_wqe;
	struct dummynet_event dn_ev_arg;
};

static void
dummynet_event_callback(struct nwk_wq_entry *nwk_item)
{
	struct dn_event_nwk_wq_entry *p_ev;

	p_ev = __container_of(nwk_item, struct dn_event_nwk_wq_entry, nwk_wqe);

	EVENTHANDLER_INVOKE(&dummynet_evhdlr_ctxt, dummynet_event, &p_ev->dn_ev_arg);

	kfree_type(struct dn_event_nwk_wq_entry, p_ev);
}

void
dummynet_event_enqueue_nwk_wq_entry(struct dummynet_event *p_dn_event)
{
	struct dn_event_nwk_wq_entry *p_ev = NULL;

	evhlog(debug, "%s: eventhandler enqueuing event of type=dummynet_event event_code=%s",
	    __func__, dummynet_event2str(p_dn_event->dn_event_code));

	p_ev = kalloc_type(struct dn_event_nwk_wq_entry,
	    Z_WAITOK | Z_ZERO | Z_NOFAIL);
	p_ev->nwk_wqe.func = dummynet_event_callback;
	p_ev->dn_ev_arg = *p_dn_event;
	nwk_wq_enqueue(&p_ev->nwk_wqe);
}

const char *
dummynet_event2str(int event)
{
	switch (event) {
#define DUMMYNET_EVENT_TO_STRING(type) case type: return #type;
		DUMMYNET_EVENT_TO_STRING(DUMMYNET_RULE_CONFIG)
		DUMMYNET_EVENT_TO_STRING(DUMMYNET_RULE_DELETE)
		DUMMYNET_EVENT_TO_STRING(DUMMYNET_PIPE_CONFIG)
		DUMMYNET_EVENT_TO_STRING(DUMMYNET_PIPE_DELETE)
		DUMMYNET_EVENT_TO_STRING(DUMMYNET_NLC_DISABLED)
#undef DUMMYNET_EVENT_TO_STRING
	}
	return "UNKNOWN_DUMMYNET_EVENT";
}

struct dummynet_tag_container {
	struct m_tag            dtc_m_tag;
	struct dn_pkt_tag       dtc_dn_pkt_tag;
};

struct m_tag *
m_tag_kalloc_dummynet(u_int32_t id, u_int16_t type, uint16_t len, int wait)
{
	struct dummynet_tag_container *tag_container;
	struct m_tag *tag = NULL;

	assert3u(id, ==, KERNEL_MODULE_TAG_ID);
	assert3u(type, ==, KERNEL_TAG_TYPE_DUMMYNET);
	assert3u(len, ==, sizeof(struct dn_pkt_tag));

	if (len != sizeof(struct dn_pkt_tag)) {
		return NULL;
	}

	tag_container = kalloc_type(struct dummynet_tag_container, wait | M_ZERO);
	if (tag_container != NULL) {
		tag =  &tag_container->dtc_m_tag;

		assert3p(tag, ==, tag_container);

		M_TAG_INIT(tag, id, type, len, &tag_container->dtc_dn_pkt_tag, NULL);
	}

	return tag;
}

void
m_tag_kfree_dummynet(struct m_tag *tag)
{
	struct dummynet_tag_container *tag_container;

	assert3u(tag->m_tag_len, ==, sizeof(struct dn_pkt_tag));
	tag_container = __container_of(tag, struct dummynet_tag_container, dtc_m_tag);
	kfree_type(struct dummynet_tag_container, tag_container);
}

void
dummynet_register_m_tag(void)
{
	int error;

	error = m_register_internal_tag_type(KERNEL_TAG_TYPE_DUMMYNET, sizeof(struct dn_pkt_tag),
	    m_tag_kalloc_dummynet, m_tag_kfree_dummynet);

	assert3u(error, ==, 0);
}