xnu-3247.1.106.tar.gz

[apple/xnu.git] / bsd / kern / uipc_socket2.c

/*
 * Copyright (c) 1998-2015 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) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *	The Regents of the University of California.  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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *	@(#)uipc_socket2.c	8.1 (Berkeley) 6/10/93
 */
/*
 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/domain.h>
#include <sys/kernel.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mcache.h>
#include <sys/protosw.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/ev.h>
#include <kern/locks.h>
#include <net/route.h>
#include <net/content_filter.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <sys/kdebug.h>
#include <libkern/OSAtomic.h>

#if CONFIG_MACF
#include <security/mac_framework.h>
#endif

#include <mach/vm_param.h>

#if MPTCP
#include <netinet/mptcp_var.h>
#endif

#define	DBG_FNC_SBDROP		NETDBG_CODE(DBG_NETSOCK, 4)
#define	DBG_FNC_SBAPPEND	NETDBG_CODE(DBG_NETSOCK, 5)

SYSCTL_DECL(_kern_ipc);

__private_extern__ u_int32_t net_io_policy_throttle_best_effort = 0;
SYSCTL_INT(_kern_ipc, OID_AUTO, throttle_best_effort,
    CTLFLAG_RW | CTLFLAG_LOCKED, &net_io_policy_throttle_best_effort, 0, "");

static inline void sbcompress(struct sockbuf *, struct mbuf *, struct mbuf *);
static struct socket *sonewconn_internal(struct socket *, int);
static int sbappendaddr_internal(struct sockbuf *, struct sockaddr *,
    struct mbuf *, struct mbuf *);
static int sbappendcontrol_internal(struct sockbuf *, struct mbuf *,
    struct mbuf *);
static void soevent_ifdenied(struct socket *);

/*
 * Primitive routines for operating on sockets and socket buffers
 */
static int soqlimitcompat = 1;
static int soqlencomp = 0;

/*
 * Based on the number of mbuf clusters configured, high_sb_max and sb_max can
 * get scaled up or down to suit that memory configuration. high_sb_max is a
 * higher limit on sb_max that is checked when sb_max gets set through sysctl.
 */

u_int32_t	sb_max = SB_MAX;		/* XXX should be static */
u_int32_t	high_sb_max = SB_MAX;

static	u_int32_t sb_efficiency = 8;	/* parameter for sbreserve() */
int32_t total_sbmb_cnt __attribute__((aligned(8))) = 0;
int32_t total_sbmb_cnt_peak __attribute__((aligned(8))) = 0;
int32_t total_snd_byte_count __attribute__((aligned(8))) = 0;
int64_t sbmb_limreached __attribute__((aligned(8))) = 0;

/* Control whether to throttle sockets eligible to be throttled */
__private_extern__ u_int32_t net_io_policy_throttled = 0;
static int sysctl_io_policy_throttled SYSCTL_HANDLER_ARGS;

u_int32_t net_io_policy_log = 0;	/* log socket policy changes */
#if CONFIG_PROC_UUID_POLICY
u_int32_t net_io_policy_uuid = 1;	/* enable UUID socket policy */
#endif /* CONFIG_PROC_UUID_POLICY */

/*
 * Procedures to manipulate state flags of socket
 * and do appropriate wakeups.  Normal sequence from the
 * active (originating) side is that soisconnecting() is
 * called during processing of connect() call,
 * resulting in an eventual call to soisconnected() if/when the
 * connection is established.  When the connection is torn down
 * soisdisconnecting() is called during processing of disconnect() call,
 * and soisdisconnected() is called when the connection to the peer
 * is totally severed.  The semantics of these routines are such that
 * connectionless protocols can call soisconnected() and soisdisconnected()
 * only, bypassing the in-progress calls when setting up a ``connection''
 * takes no time.
 *
 * From the passive side, a socket is created with
 * two queues of sockets: so_incomp for connections in progress
 * and so_comp for connections already made and awaiting user acceptance.
 * As a protocol is preparing incoming connections, it creates a socket
 * structure queued on so_incomp by calling sonewconn().  When the connection
 * is established, soisconnected() is called, and transfers the
 * socket structure to so_comp, making it available to accept().
 *
 * If a socket is closed with sockets on either
 * so_incomp or so_comp, these sockets are dropped.
 *
 * If higher level protocols are implemented in
 * the kernel, the wakeups done here will sometimes
 * cause software-interrupt process scheduling.
 */
void
soisconnecting(struct socket *so)
{

	so->so_state &= ~(SS_ISCONNECTED|SS_ISDISCONNECTING);
	so->so_state |= SS_ISCONNECTING;

	sflt_notify(so, sock_evt_connecting, NULL);
}

void
soisconnected(struct socket *so)
{
	struct socket *head = so->so_head;

	so->so_state &= ~(SS_ISCONNECTING|SS_ISDISCONNECTING|SS_ISCONFIRMING);
	so->so_state |= SS_ISCONNECTED;

	soreserve_preconnect(so, 0);

	sflt_notify(so, sock_evt_connected, NULL);

	if (head && (so->so_state & SS_INCOMP)) {
		so->so_state &= ~SS_INCOMP;
		so->so_state |= SS_COMP;
		if (head->so_proto->pr_getlock != NULL) {
			socket_unlock(so, 0);
			socket_lock(head, 1);
		}
		postevent(head, 0, EV_RCONN);
		TAILQ_REMOVE(&head->so_incomp, so, so_list);
		head->so_incqlen--;
		TAILQ_INSERT_TAIL(&head->so_comp, so, so_list);
		sorwakeup(head);
		wakeup_one((caddr_t)&head->so_timeo);
		if (head->so_proto->pr_getlock != NULL) {
			socket_unlock(head, 1);
			socket_lock(so, 0);
		}
	} else {
		postevent(so, 0, EV_WCONN);
		wakeup((caddr_t)&so->so_timeo);
		sorwakeup(so);
		sowwakeup(so);
		soevent(so, SO_FILT_HINT_LOCKED | SO_FILT_HINT_CONNECTED |
		    SO_FILT_HINT_CONNINFO_UPDATED);
	}
}

boolean_t
socanwrite(struct socket *so)
{
	return ((so->so_state & SS_ISCONNECTED) ||
	       !(so->so_proto->pr_flags & PR_CONNREQUIRED) ||
	       (so->so_flags1 & SOF1_PRECONNECT_DATA));

}

void
soisdisconnecting(struct socket *so)
{
	so->so_state &= ~SS_ISCONNECTING;
	so->so_state |= (SS_ISDISCONNECTING|SS_CANTRCVMORE|SS_CANTSENDMORE);
	soevent(so, SO_FILT_HINT_LOCKED);
	sflt_notify(so, sock_evt_disconnecting, NULL);
	wakeup((caddr_t)&so->so_timeo);
	sowwakeup(so);
	sorwakeup(so);
}

void
soisdisconnected(struct socket *so)
{
	so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
	so->so_state |= (SS_CANTRCVMORE|SS_CANTSENDMORE|SS_ISDISCONNECTED);
	soevent(so, SO_FILT_HINT_LOCKED | SO_FILT_HINT_DISCONNECTED |
	    SO_FILT_HINT_CONNINFO_UPDATED);
	sflt_notify(so, sock_evt_disconnected, NULL);
	wakeup((caddr_t)&so->so_timeo);
	sowwakeup(so);
	sorwakeup(so);

#if CONTENT_FILTER
	/* Notify content filters as soon as we cannot send/receive data */
	cfil_sock_notify_shutdown(so, SHUT_RDWR);
#endif /* CONTENT_FILTER */
}

/*
 * This function will issue a wakeup like soisdisconnected but it will not
 * notify the socket filters. This will avoid unlocking the socket
 * in the midst of closing it.
 */
void
sodisconnectwakeup(struct socket *so)
{
	so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
	so->so_state |= (SS_CANTRCVMORE|SS_CANTSENDMORE|SS_ISDISCONNECTED);
	soevent(so, SO_FILT_HINT_LOCKED | SO_FILT_HINT_DISCONNECTED |
	    SO_FILT_HINT_CONNINFO_UPDATED);
	wakeup((caddr_t)&so->so_timeo);
	sowwakeup(so);
	sorwakeup(so);

#if CONTENT_FILTER
	/* Notify content filters as soon as we cannot send/receive data */
	cfil_sock_notify_shutdown(so, SHUT_RDWR);
#endif /* CONTENT_FILTER */
}

/*
 * When an attempt at a new connection is noted on a socket
 * which accepts connections, sonewconn is called.  If the
 * connection is possible (subject to space constraints, etc.)
 * then we allocate a new structure, propoerly linked into the
 * data structure of the original socket, and return this.
 * Connstatus may be 0, or SO_ISCONFIRMING, or SO_ISCONNECTED.
 */
static struct socket *
sonewconn_internal(struct socket *head, int connstatus)
{
	int so_qlen, error = 0;
	struct socket *so;
	lck_mtx_t *mutex_held;

	if (head->so_proto->pr_getlock != NULL)
		mutex_held = (*head->so_proto->pr_getlock)(head, 0);
	else
		mutex_held = head->so_proto->pr_domain->dom_mtx;
	lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

	if (!soqlencomp) {
		/*
		 * This is the default case; so_qlen represents the
		 * sum of both incomplete and completed queues.
		 */
		so_qlen = head->so_qlen;
	} else {
		/*
		 * When kern.ipc.soqlencomp is set to 1, so_qlen
		 * represents only the completed queue.  Since we
		 * cannot let the incomplete queue goes unbounded
		 * (in case of SYN flood), we cap the incomplete
		 * queue length to at most somaxconn, and use that
		 * as so_qlen so that we fail immediately below.
		 */
		so_qlen = head->so_qlen - head->so_incqlen;
		if (head->so_incqlen > somaxconn)
			so_qlen = somaxconn;
	}

	if (so_qlen >=
	    (soqlimitcompat ? head->so_qlimit : (3 * head->so_qlimit / 2)))
		return ((struct socket *)0);
	so = soalloc(1, SOCK_DOM(head), head->so_type);
	if (so == NULL)
		return ((struct socket *)0);
	/* check if head was closed during the soalloc */
	if (head->so_proto == NULL) {
		sodealloc(so);
		return ((struct socket *)0);
	}

	so->so_type = head->so_type;
	so->so_options = head->so_options &~ SO_ACCEPTCONN;
	so->so_linger = head->so_linger;
	so->so_state = head->so_state | SS_NOFDREF;
	so->so_proto = head->so_proto;
	so->so_timeo = head->so_timeo;
	so->so_pgid  = head->so_pgid;
	kauth_cred_ref(head->so_cred);
	so->so_cred = head->so_cred;
	so->last_pid = head->last_pid;
	so->last_upid = head->last_upid;
	memcpy(so->last_uuid, head->last_uuid, sizeof (so->last_uuid));
	if (head->so_flags & SOF_DELEGATED) {
		so->e_pid = head->e_pid;
		so->e_upid = head->e_upid;
		memcpy(so->e_uuid, head->e_uuid, sizeof (so->e_uuid));
	}
	/* inherit socket options stored in so_flags */
	so->so_flags = head->so_flags &
	    (SOF_NOSIGPIPE | SOF_NOADDRAVAIL | SOF_REUSESHAREUID |
	    SOF_NOTIFYCONFLICT | SOF_BINDRANDOMPORT | SOF_NPX_SETOPTSHUT |
	    SOF_NODEFUNCT | SOF_PRIVILEGED_TRAFFIC_CLASS| SOF_NOTSENT_LOWAT |
	    SOF_USELRO | SOF_DELEGATED);
	so->so_usecount = 1;
	so->next_lock_lr = 0;
	so->next_unlock_lr = 0;

	so->so_rcv.sb_flags |= SB_RECV;	/* XXX */
	so->so_rcv.sb_so = so->so_snd.sb_so = so;
	TAILQ_INIT(&so->so_evlist);

#if CONFIG_MACF_SOCKET
	mac_socket_label_associate_accept(head, so);
#endif

	/* inherit traffic management properties of listener */
	so->so_traffic_mgt_flags =
	    head->so_traffic_mgt_flags & (TRAFFIC_MGT_SO_BACKGROUND);
	so->so_background_thread = head->so_background_thread;
	so->so_traffic_class = head->so_traffic_class;

	if (soreserve(so, head->so_snd.sb_hiwat, head->so_rcv.sb_hiwat)) {
		sodealloc(so);
		return ((struct socket *)0);
	}
	so->so_rcv.sb_flags |= (head->so_rcv.sb_flags & SB_USRSIZE);
	so->so_snd.sb_flags |= (head->so_snd.sb_flags & SB_USRSIZE);

	/*
	 * Must be done with head unlocked to avoid deadlock
	 * for protocol with per socket mutexes.
	 */
	if (head->so_proto->pr_unlock)
		socket_unlock(head, 0);
	if (((*so->so_proto->pr_usrreqs->pru_attach)(so, 0, NULL) != 0) ||
	    error) {
		sodealloc(so);
		if (head->so_proto->pr_unlock)
			socket_lock(head, 0);
		return ((struct socket *)0);
	}
	if (head->so_proto->pr_unlock) {
		socket_lock(head, 0);
		/*
		 * Radar 7385998 Recheck that the head is still accepting
		 * to avoid race condition when head is getting closed.
		 */
		if ((head->so_options & SO_ACCEPTCONN) == 0) {
			so->so_state &= ~SS_NOFDREF;
			soclose(so);
			return ((struct socket *)0);
		}
	}

	atomic_add_32(&so->so_proto->pr_domain->dom_refs, 1);

	/* Insert in head appropriate lists */
	so->so_head = head;

	/*
	 * Since this socket is going to be inserted into the incomp
	 * queue, it can be picked up by another thread in
	 * tcp_dropdropablreq to get dropped before it is setup..
	 * To prevent this race, set in-progress flag which can be
	 * cleared later
	 */
	so->so_flags |= SOF_INCOMP_INPROGRESS;

	if (connstatus) {
		TAILQ_INSERT_TAIL(&head->so_comp, so, so_list);
		so->so_state |= SS_COMP;
	} else {
		TAILQ_INSERT_TAIL(&head->so_incomp, so, so_list);
		so->so_state |= SS_INCOMP;
		head->so_incqlen++;
	}
	head->so_qlen++;

	/* Attach socket filters for this protocol */
	sflt_initsock(so);

	if (connstatus) {
		so->so_state |= connstatus;
		sorwakeup(head);
		wakeup((caddr_t)&head->so_timeo);
	}
	return (so);
}


struct socket *
sonewconn(struct socket *head, int connstatus, const struct sockaddr *from)
{
	int error = sflt_connectin(head, from);
	if (error) {
		return (NULL);
	}

	return (sonewconn_internal(head, connstatus));
}

/*
 * Socantsendmore indicates that no more data will be sent on the
 * socket; it would normally be applied to a socket when the user
 * informs the system that no more data is to be sent, by the protocol
 * code (in case PRU_SHUTDOWN).  Socantrcvmore indicates that no more data
 * will be received, and will normally be applied to the socket by a
 * protocol when it detects that the peer will send no more data.
 * Data queued for reading in the socket may yet be read.
 */

void
socantsendmore(struct socket *so)
{
	so->so_state |= SS_CANTSENDMORE;
	soevent(so, SO_FILT_HINT_LOCKED | SO_FILT_HINT_CANTSENDMORE);
	sflt_notify(so, sock_evt_cantsendmore, NULL);
	sowwakeup(so);
}

void
socantrcvmore(struct socket *so)
{
	so->so_state |= SS_CANTRCVMORE;
	soevent(so, SO_FILT_HINT_LOCKED | SO_FILT_HINT_CANTRCVMORE);
	sflt_notify(so, sock_evt_cantrecvmore, NULL);
	sorwakeup(so);
}

/*
 * Wait for data to arrive at/drain from a socket buffer.
 */
int
sbwait(struct sockbuf *sb)
{
	boolean_t nointr = (sb->sb_flags & SB_NOINTR);
	void *lr_saved = __builtin_return_address(0);
	struct socket *so = sb->sb_so;
	lck_mtx_t *mutex_held;
	struct timespec ts;
	int error = 0;

	if (so == NULL) {
		panic("%s: null so, sb=%p sb_flags=0x%x lr=%p\n",
		    __func__, sb, sb->sb_flags, lr_saved);
		/* NOTREACHED */
	} else if (so->so_usecount < 1) {
		panic("%s: sb=%p sb_flags=0x%x sb_so=%p usecount=%d lr=%p "
		    "lrh= %s\n", __func__, sb, sb->sb_flags, so,
		    so->so_usecount, lr_saved, solockhistory_nr(so));
		/* NOTREACHED */
	}

	if (so->so_proto->pr_getlock != NULL)
		mutex_held = (*so->so_proto->pr_getlock)(so, 0);
	else
		mutex_held = so->so_proto->pr_domain->dom_mtx;

	lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

	ts.tv_sec = sb->sb_timeo.tv_sec;
	ts.tv_nsec = sb->sb_timeo.tv_usec * 1000;

	sb->sb_waiters++;
	VERIFY(sb->sb_waiters != 0);

	error = msleep((caddr_t)&sb->sb_cc, mutex_held,
	    nointr ? PSOCK : PSOCK | PCATCH,
	    nointr ? "sbwait_nointr" : "sbwait", &ts);

	VERIFY(sb->sb_waiters != 0);
	sb->sb_waiters--;

	if (so->so_usecount < 1) {
		panic("%s: 2 sb=%p sb_flags=0x%x sb_so=%p usecount=%d lr=%p "
		    "lrh= %s\n", __func__, sb, sb->sb_flags, so,
		    so->so_usecount, lr_saved, solockhistory_nr(so));
		/* NOTREACHED */
	}

	if ((so->so_state & SS_DRAINING) || (so->so_flags & SOF_DEFUNCT)) {
		error = EBADF;
		if (so->so_flags & SOF_DEFUNCT) {
			SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] "
			    "(%d)\n", __func__, proc_selfpid(),
			    (uint64_t)VM_KERNEL_ADDRPERM(so),
			    SOCK_DOM(so), SOCK_TYPE(so), error));
		}
	}

	return (error);
}

void
sbwakeup(struct sockbuf *sb)
{
	if (sb->sb_waiters > 0)
		wakeup((caddr_t)&sb->sb_cc);
}

/*
 * Wakeup processes waiting on a socket buffer.
 * Do asynchronous notification via SIGIO
 * if the socket has the SS_ASYNC flag set.
 */
void
sowakeup(struct socket *so, struct sockbuf *sb)
{
	if (so->so_flags & SOF_DEFUNCT) {
		SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] si 0x%x, "
		    "fl 0x%x [%s]\n", __func__, proc_selfpid(),
		    (uint64_t)VM_KERNEL_ADDRPERM(so), SOCK_DOM(so),
		    SOCK_TYPE(so), (uint32_t)sb->sb_sel.si_flags, sb->sb_flags,
		    (sb->sb_flags & SB_RECV) ? "rcv" : "snd"));
	}

	sb->sb_flags &= ~SB_SEL;
	selwakeup(&sb->sb_sel);
	sbwakeup(sb);
	if (so->so_state & SS_ASYNC) {
		if (so->so_pgid < 0)
			gsignal(-so->so_pgid, SIGIO);
		else if (so->so_pgid > 0)
			proc_signal(so->so_pgid, SIGIO);
	}
	if (sb->sb_flags & SB_KNOTE) {
		KNOTE(&sb->sb_sel.si_note, SO_FILT_HINT_LOCKED);
	}
	if (sb->sb_flags & SB_UPCALL) {
		void (*sb_upcall)(struct socket *, void *, int);
		caddr_t sb_upcallarg;

		sb_upcall = sb->sb_upcall;
		sb_upcallarg = sb->sb_upcallarg;
		/* Let close know that we're about to do an upcall */
		so->so_upcallusecount++;

		socket_unlock(so, 0);
		(*sb_upcall)(so, sb_upcallarg, M_DONTWAIT);
		socket_lock(so, 0);

		so->so_upcallusecount--;
		/* Tell close that it's safe to proceed */
		if ((so->so_flags & SOF_CLOSEWAIT) &&
		    so->so_upcallusecount == 0)
			wakeup((caddr_t)&so->so_upcallusecount);
	}
#if CONTENT_FILTER
	/*
	 * Trap disconnection events for content filters
	 */
	if ((so->so_flags & SOF_CONTENT_FILTER) != 0) {
		if ((sb->sb_flags & SB_RECV)) {
			if (so->so_state & (SS_CANTRCVMORE))
				cfil_sock_notify_shutdown(so, SHUT_RD);
		} else {
			if (so->so_state & (SS_CANTSENDMORE))
				cfil_sock_notify_shutdown(so, SHUT_WR);
		}
	}
#endif /* CONTENT_FILTER */
}

/*
 * Socket buffer (struct sockbuf) utility routines.
 *
 * Each socket contains two socket buffers: one for sending data and
 * one for receiving data.  Each buffer contains a queue of mbufs,
 * information about the number of mbufs and amount of data in the
 * queue, and other fields allowing select() statements and notification
 * on data availability to be implemented.
 *
 * Data stored in a socket buffer is maintained as a list of records.
 * Each record is a list of mbufs chained together with the m_next
 * field.  Records are chained together with the m_nextpkt field. The upper
 * level routine soreceive() expects the following conventions to be
 * observed when placing information in the receive buffer:
 *
 * 1. If the protocol requires each message be preceded by the sender's
 *    name, then a record containing that name must be present before
 *    any associated data (mbuf's must be of type MT_SONAME).
 * 2. If the protocol supports the exchange of ``access rights'' (really
 *    just additional data associated with the message), and there are
 *    ``rights'' to be received, then a record containing this data
 *    should be present (mbuf's must be of type MT_RIGHTS).
 * 3. If a name or rights record exists, then it must be followed by
 *    a data record, perhaps of zero length.
 *
 * Before using a new socket structure it is first necessary to reserve
 * buffer space to the socket, by calling sbreserve().  This should commit
 * some of the available buffer space in the system buffer pool for the
 * socket (currently, it does nothing but enforce limits).  The space
 * should be released by calling sbrelease() when the socket is destroyed.
 */

/*
 * Returns:	0			Success
 *		ENOBUFS
 */
int
soreserve(struct socket *so, u_int32_t sndcc, u_int32_t rcvcc)
{

	if (sbreserve(&so->so_snd, sndcc) == 0)
		goto bad;
	else
		so->so_snd.sb_idealsize = sndcc;

	if (sbreserve(&so->so_rcv, rcvcc) == 0)
		goto bad2;
	else
		so->so_rcv.sb_idealsize = rcvcc;

	if (so->so_rcv.sb_lowat == 0)
		so->so_rcv.sb_lowat = 1;
	if (so->so_snd.sb_lowat == 0)
		so->so_snd.sb_lowat = MCLBYTES;
	if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
		so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
	return (0);
bad2:
	so->so_snd.sb_flags &= ~SB_SEL;
	selthreadclear(&so->so_snd.sb_sel);
	sbrelease(&so->so_snd);
bad:
	return (ENOBUFS);
}

void
soreserve_preconnect(struct socket *so, unsigned int pre_cc)
{
	/* As of now, same bytes for both preconnect read and write */
	so->so_snd.sb_preconn_hiwat = pre_cc;
	so->so_rcv.sb_preconn_hiwat = pre_cc;
}

/*
 * Allot mbufs to a sockbuf.
 * Attempt to scale mbmax so that mbcnt doesn't become limiting
 * if buffering efficiency is near the normal case.
 */
int
sbreserve(struct sockbuf *sb, u_int32_t cc)
{
	if ((u_quad_t)cc > (u_quad_t)sb_max * MCLBYTES / (MSIZE + MCLBYTES))
		return (0);
	sb->sb_hiwat = cc;
	sb->sb_mbmax = min(cc * sb_efficiency, sb_max);
	if (sb->sb_lowat > sb->sb_hiwat)
		sb->sb_lowat = sb->sb_hiwat;
	return (1);
}

/*
 * Free mbufs held by a socket, and reserved mbuf space.
 */
/*  WARNING needs to do selthreadclear() before calling this */
void
sbrelease(struct sockbuf *sb)
{
	sbflush(sb);
	sb->sb_hiwat = 0;
	sb->sb_mbmax = 0;
}

/*
 * Routines to add and remove
 * data from an mbuf queue.
 *
 * The routines sbappend() or sbappendrecord() are normally called to
 * append new mbufs to a socket buffer, after checking that adequate
 * space is available, comparing the function sbspace() with the amount
 * of data to be added.  sbappendrecord() differs from sbappend() in
 * that data supplied is treated as the beginning of a new record.
 * To place a sender's address, optional access rights, and data in a
 * socket receive buffer, sbappendaddr() should be used.  To place
 * access rights and data in a socket receive buffer, sbappendrights()
 * should be used.  In either case, the new data begins a new record.
 * Note that unlike sbappend() and sbappendrecord(), these routines check
 * for the caller that there will be enough space to store the data.
 * Each fails if there is not enough space, or if it cannot find mbufs
 * to store additional information in.
 *
 * Reliable protocols may use the socket send buffer to hold data
 * awaiting acknowledgement.  Data is normally copied from a socket
 * send buffer in a protocol with m_copy for output to a peer,
 * and then removing the data from the socket buffer with sbdrop()
 * or sbdroprecord() when the data is acknowledged by the peer.
 */

/*
 * Append mbuf chain m to the last record in the
 * socket buffer sb.  The additional space associated
 * the mbuf chain is recorded in sb.  Empty mbufs are
 * discarded and mbufs are compacted where possible.
 */
int
sbappend(struct sockbuf *sb, struct mbuf *m)
{
	struct socket *so = sb->sb_so;

	if (m == NULL || (sb->sb_flags & SB_DROP)) {
		if (m != NULL)
			m_freem(m);
		return (0);
	}

	SBLASTRECORDCHK(sb, "sbappend 1");

	if (sb->sb_lastrecord != NULL && (sb->sb_mbtail->m_flags & M_EOR))
		return (sbappendrecord(sb, m));

	if (sb->sb_flags & SB_RECV && !(m && m->m_flags & M_SKIPCFIL)) {
		int error = sflt_data_in(so, NULL, &m, NULL, 0);
		SBLASTRECORDCHK(sb, "sbappend 2");

#if CONTENT_FILTER
		if (error == 0)
			error = cfil_sock_data_in(so, NULL, m, NULL, 0);
#endif /* CONTENT_FILTER */

		if (error != 0) {
			if (error != EJUSTRETURN)
				m_freem(m);
			return (0);
		}
	} else if (m) {
		m->m_flags &= ~M_SKIPCFIL;
	}

	/* If this is the first record, it's also the last record */
	if (sb->sb_lastrecord == NULL)
		sb->sb_lastrecord = m;

	sbcompress(sb, m, sb->sb_mbtail);
	SBLASTRECORDCHK(sb, "sbappend 3");
	return (1);
}

/*
 * Similar to sbappend, except that this is optimized for stream sockets.
 */
int
sbappendstream(struct sockbuf *sb, struct mbuf *m)
{
	struct socket *so = sb->sb_so;

	if (m == NULL || (sb->sb_flags & SB_DROP)) {
		if (m != NULL)
			m_freem(m);
		return (0);
	}

	if (m->m_nextpkt != NULL || (sb->sb_mb != sb->sb_lastrecord)) {
		panic("sbappendstream: nexpkt %p || mb %p != lastrecord %p\n",
		    m->m_nextpkt, sb->sb_mb, sb->sb_lastrecord);
		/* NOTREACHED */
	}

	SBLASTMBUFCHK(sb, __func__);

	if (sb->sb_flags & SB_RECV && !(m && m->m_flags & M_SKIPCFIL)) {
		int error = sflt_data_in(so, NULL, &m, NULL, 0);
		SBLASTRECORDCHK(sb, "sbappendstream 1");

#if CONTENT_FILTER
		if (error == 0)
			error = cfil_sock_data_in(so, NULL, m, NULL, 0);
#endif /* CONTENT_FILTER */

		if (error != 0) {
			if (error != EJUSTRETURN)
				m_freem(m);
			return (0);
		}
	} else if (m) {
		m->m_flags &= ~M_SKIPCFIL;
	}

	sbcompress(sb, m, sb->sb_mbtail);
	sb->sb_lastrecord = sb->sb_mb;
	SBLASTRECORDCHK(sb, "sbappendstream 2");
	return (1);
}

#ifdef SOCKBUF_DEBUG
void
sbcheck(struct sockbuf *sb)
{
	struct mbuf *m;
	struct mbuf *n = 0;
	u_int32_t len = 0, mbcnt = 0;
	lck_mtx_t *mutex_held;

	if (sb->sb_so->so_proto->pr_getlock != NULL)
		mutex_held = (*sb->sb_so->so_proto->pr_getlock)(sb->sb_so, 0);
	else
		mutex_held = sb->sb_so->so_proto->pr_domain->dom_mtx;

	lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

	if (sbchecking == 0)
		return;

	for (m = sb->sb_mb; m; m = n) {
		n = m->m_nextpkt;
		for (; m; m = m->m_next) {
			len += m->m_len;
			mbcnt += MSIZE;
			/* XXX pretty sure this is bogus */
			if (m->m_flags & M_EXT)
				mbcnt += m->m_ext.ext_size;
		}
	}
	if (len != sb->sb_cc || mbcnt != sb->sb_mbcnt) {
		panic("cc %ld != %ld || mbcnt %ld != %ld\n", len, sb->sb_cc,
		    mbcnt, sb->sb_mbcnt);
	}
}
#endif

void
sblastrecordchk(struct sockbuf *sb, const char *where)
{
	struct mbuf *m = sb->sb_mb;

	while (m && m->m_nextpkt)
		m = m->m_nextpkt;

	if (m != sb->sb_lastrecord) {
		printf("sblastrecordchk: mb 0x%llx lastrecord 0x%llx "
		    "last 0x%llx\n",
		    (uint64_t)VM_KERNEL_ADDRPERM(sb->sb_mb),
		    (uint64_t)VM_KERNEL_ADDRPERM(sb->sb_lastrecord),
		    (uint64_t)VM_KERNEL_ADDRPERM(m));
		printf("packet chain:\n");
		for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt)
			printf("\t0x%llx\n", (uint64_t)VM_KERNEL_ADDRPERM(m));
		panic("sblastrecordchk from %s", where);
	}
}

void
sblastmbufchk(struct sockbuf *sb, const char *where)
{
	struct mbuf *m = sb->sb_mb;
	struct mbuf *n;

	while (m && m->m_nextpkt)
		m = m->m_nextpkt;

	while (m && m->m_next)
		m = m->m_next;

	if (m != sb->sb_mbtail) {
		printf("sblastmbufchk: mb 0x%llx mbtail 0x%llx last 0x%llx\n",
		    (uint64_t)VM_KERNEL_ADDRPERM(sb->sb_mb),
		    (uint64_t)VM_KERNEL_ADDRPERM(sb->sb_mbtail),
		    (uint64_t)VM_KERNEL_ADDRPERM(m));
		printf("packet tree:\n");
		for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt) {
			printf("\t");
			for (n = m; n != NULL; n = n->m_next)
				printf("0x%llx ",
				    (uint64_t)VM_KERNEL_ADDRPERM(n));
			printf("\n");
		}
		panic("sblastmbufchk from %s", where);
	}
}

/*
 * Similar to sbappend, except the mbuf chain begins a new record.
 */
int
sbappendrecord(struct sockbuf *sb, struct mbuf *m0)
{
	struct mbuf *m;
	int space = 0;

	if (m0 == NULL || (sb->sb_flags & SB_DROP)) {
		if (m0 != NULL)
			m_freem(m0);
		return (0);
	}

	for (m = m0; m != NULL; m = m->m_next)
		space += m->m_len;

	if (space > sbspace(sb) && !(sb->sb_flags & SB_UNIX)) {
		m_freem(m0);
		return (0);
	}

	if (sb->sb_flags & SB_RECV && !(m0 && m0->m_flags & M_SKIPCFIL)) {
		int error = sflt_data_in(sb->sb_so, NULL, &m0, NULL,
		    sock_data_filt_flag_record);

#if CONTENT_FILTER
		if (error == 0)
			error = cfil_sock_data_in(sb->sb_so, NULL, m0, NULL, 0);
#endif /* CONTENT_FILTER */

		if (error != 0) {
			SBLASTRECORDCHK(sb, "sbappendrecord 1");
			if (error != EJUSTRETURN)
				m_freem(m0);
			return (0);
		}
	} else if (m0) {
		m0->m_flags &= ~M_SKIPCFIL;
	}

	/*
	 * Note this permits zero length records.
	 */
	sballoc(sb, m0);
	SBLASTRECORDCHK(sb, "sbappendrecord 2");
	if (sb->sb_lastrecord != NULL) {
		sb->sb_lastrecord->m_nextpkt = m0;
	} else {
		sb->sb_mb = m0;
	}
	sb->sb_lastrecord = m0;
	sb->sb_mbtail = m0;

	m = m0->m_next;
	m0->m_next = 0;
	if (m && (m0->m_flags & M_EOR)) {
		m0->m_flags &= ~M_EOR;
		m->m_flags |= M_EOR;
	}
	sbcompress(sb, m, m0);
	SBLASTRECORDCHK(sb, "sbappendrecord 3");
	return (1);
}

/*
 * As above except that OOB data
 * is inserted at the beginning of the sockbuf,
 * but after any other OOB data.
 */
int
sbinsertoob(struct sockbuf *sb, struct mbuf *m0)
{
	struct mbuf *m;
	struct mbuf **mp;

	if (m0 == 0)
		return (0);

	SBLASTRECORDCHK(sb, "sbinsertoob 1");

	if ((sb->sb_flags & SB_RECV && !(m0->m_flags & M_SKIPCFIL)) != 0) {
		int error = sflt_data_in(sb->sb_so, NULL, &m0, NULL,
		    sock_data_filt_flag_oob);

		SBLASTRECORDCHK(sb, "sbinsertoob 2");

#if CONTENT_FILTER
		if (error == 0)
			error = cfil_sock_data_in(sb->sb_so, NULL, m0, NULL, 0);
#endif /* CONTENT_FILTER */

		if (error) {
			if (error != EJUSTRETURN) {
				m_freem(m0);
			}
			return (0);
		}
	} else if (m0) {
		m0->m_flags &= ~M_SKIPCFIL;
	}

	for (mp = &sb->sb_mb; *mp; mp = &((*mp)->m_nextpkt)) {
		m = *mp;
again:
		switch (m->m_type) {

		case MT_OOBDATA:
			continue;		/* WANT next train */

		case MT_CONTROL:
			m = m->m_next;
			if (m)
				goto again;	/* inspect THIS train further */
		}
		break;
	}
	/*
	 * Put the first mbuf on the queue.
	 * Note this permits zero length records.
	 */
	sballoc(sb, m0);
	m0->m_nextpkt = *mp;
	if (*mp == NULL) {
		/* m0 is actually the new tail */
		sb->sb_lastrecord = m0;
	}
	*mp = m0;
	m = m0->m_next;
	m0->m_next = 0;
	if (m && (m0->m_flags & M_EOR)) {
		m0->m_flags &= ~M_EOR;
		m->m_flags |= M_EOR;
	}
	sbcompress(sb, m, m0);
	SBLASTRECORDCHK(sb, "sbinsertoob 3");
	return (1);
}

/*
 * Append address and data, and optionally, control (ancillary) data
 * to the receive queue of a socket.  If present,
 * m0 must include a packet header with total length.
 * Returns 0 if no space in sockbuf or insufficient mbufs.
 *
 * Returns:	0			No space/out of mbufs
 *		1			Success
 */
static int
sbappendaddr_internal(struct sockbuf *sb, struct sockaddr *asa,
    struct mbuf *m0, struct mbuf *control)
{
	struct mbuf *m, *n, *nlast;
	int space = asa->sa_len;

	if (m0 && (m0->m_flags & M_PKTHDR) == 0)
		panic("sbappendaddr");

	if (m0)
		space += m0->m_pkthdr.len;
	for (n = control; n; n = n->m_next) {
		space += n->m_len;
		if (n->m_next == 0)	/* keep pointer to last control buf */
			break;
	}
	if (space > sbspace(sb))
		return (0);
	if (asa->sa_len > MLEN)
		return (0);
	MGET(m, M_DONTWAIT, MT_SONAME);
	if (m == 0)
		return (0);
	m->m_len = asa->sa_len;
	bcopy((caddr_t)asa, mtod(m, caddr_t), asa->sa_len);
	if (n)
		n->m_next = m0;		/* concatenate data to control */
	else
		control = m0;
	m->m_next = control;

	SBLASTRECORDCHK(sb, "sbappendadddr 1");

	for (n = m; n->m_next != NULL; n = n->m_next)
		sballoc(sb, n);
	sballoc(sb, n);
	nlast = n;

	if (sb->sb_lastrecord != NULL) {
		sb->sb_lastrecord->m_nextpkt = m;
	} else {
		sb->sb_mb = m;
	}
	sb->sb_lastrecord = m;
	sb->sb_mbtail = nlast;

	SBLASTMBUFCHK(sb, __func__);
	SBLASTRECORDCHK(sb, "sbappendadddr 2");

	postevent(0, sb, EV_RWBYTES);
	return (1);
}

/*
 * Returns:	0			Error: No space/out of mbufs/etc.
 *		1			Success
 *
 * Imputed:	(*error_out)		errno for error
 *		ENOBUFS
 *	sflt_data_in:???		[whatever a filter author chooses]
 */
int
sbappendaddr(struct sockbuf *sb, struct sockaddr *asa, struct mbuf *m0,
    struct mbuf *control, int *error_out)
{
	int result = 0;
	boolean_t sb_unix = (sb->sb_flags & SB_UNIX);

	if (error_out)
		*error_out = 0;

	if (m0 && (m0->m_flags & M_PKTHDR) == 0)
		panic("sbappendaddrorfree");

	if (sb->sb_flags & SB_DROP) {
		if (m0 != NULL)
			m_freem(m0);
		if (control != NULL && !sb_unix)
			m_freem(control);
		if (error_out != NULL)
			*error_out = EINVAL;
		return (0);
	}

	/* Call socket data in filters */
	if (sb->sb_flags & SB_RECV && !(m0 && m0->m_flags & M_SKIPCFIL)) {
		int error;
		error = sflt_data_in(sb->sb_so, asa, &m0, &control, 0);
		SBLASTRECORDCHK(sb, __func__);

#if CONTENT_FILTER
		if (error == 0)
			error = cfil_sock_data_in(sb->sb_so, asa, m0, control,
			    0);
#endif /* CONTENT_FILTER */

		if (error) {
			if (error != EJUSTRETURN) {
				if (m0)
					m_freem(m0);
				if (control != NULL && !sb_unix)
					m_freem(control);
				if (error_out)
					*error_out = error;
			}
			return (0);
		}
	} else if (m0) {
		m0->m_flags &= ~M_SKIPCFIL;
	}

	result = sbappendaddr_internal(sb, asa, m0, control);
	if (result == 0) {
		if (m0)
			m_freem(m0);
		if (control != NULL && !sb_unix)
			m_freem(control);
		if (error_out)
			*error_out = ENOBUFS;
	}

	return (result);
}

static int
sbappendcontrol_internal(struct sockbuf *sb, struct mbuf *m0,
    struct mbuf *control)
{
	struct mbuf *m, *mlast, *n;
	int space = 0;

	if (control == 0)
		panic("sbappendcontrol");

	for (m = control; ; m = m->m_next) {
		space += m->m_len;
		if (m->m_next == 0)
			break;
	}
	n = m;			/* save pointer to last control buffer */
	for (m = m0; m; m = m->m_next)
		space += m->m_len;
	if (space > sbspace(sb) && !(sb->sb_flags & SB_UNIX))
		return (0);
	n->m_next = m0;			/* concatenate data to control */
	SBLASTRECORDCHK(sb, "sbappendcontrol 1");

	for (m = control; m->m_next != NULL; m = m->m_next)
		sballoc(sb, m);
	sballoc(sb, m);
	mlast = m;

	if (sb->sb_lastrecord != NULL) {
		sb->sb_lastrecord->m_nextpkt = control;
	} else {
		sb->sb_mb = control;
	}
	sb->sb_lastrecord = control;
	sb->sb_mbtail = mlast;

	SBLASTMBUFCHK(sb, __func__);
	SBLASTRECORDCHK(sb, "sbappendcontrol 2");

	postevent(0, sb, EV_RWBYTES);
	return (1);
}

int
sbappendcontrol(struct sockbuf *sb, struct mbuf	*m0, struct mbuf *control,
    int *error_out)
{
	int result = 0;
	boolean_t sb_unix = (sb->sb_flags & SB_UNIX);

	if (error_out)
		*error_out = 0;

	if (sb->sb_flags & SB_DROP) {
		if (m0 != NULL)
			m_freem(m0);
		if (control != NULL && !sb_unix)
			m_freem(control);
		if (error_out != NULL)
			*error_out = EINVAL;
		return (0);
	}

	if (sb->sb_flags & SB_RECV && !(m0 && m0->m_flags & M_SKIPCFIL)) {
		int error;

		error = sflt_data_in(sb->sb_so, NULL, &m0, &control, 0);
		SBLASTRECORDCHK(sb, __func__);

#if CONTENT_FILTER
		if (error == 0)
			error = cfil_sock_data_in(sb->sb_so, NULL, m0, control,
			    0);
#endif /* CONTENT_FILTER */

		if (error) {
			if (error != EJUSTRETURN) {
				if (m0)
					m_freem(m0);
				if (control != NULL && !sb_unix)
					m_freem(control);
				if (error_out)
					*error_out = error;
			}
			return (0);
		}
	} else if (m0) {
		m0->m_flags &= ~M_SKIPCFIL;
	}

	result = sbappendcontrol_internal(sb, m0, control);
	if (result == 0) {
		if (m0)
			m_freem(m0);
		if (control != NULL && !sb_unix)
			m_freem(control);
		if (error_out)
			*error_out = ENOBUFS;
	}

	return (result);
}

/*
 * Append a contiguous TCP data blob with TCP sequence number as control data
 * as a new msg to the receive socket buffer.
 */
int
sbappendmsgstream_rcv(struct sockbuf *sb, struct mbuf *m, uint32_t seqnum,
    int unordered)
{
	struct mbuf *m_eor = NULL;
	u_int32_t data_len = 0;
	int ret = 0;
	struct socket *so = sb->sb_so;

	VERIFY((m->m_flags & M_PKTHDR) && m_pktlen(m) > 0);
	VERIFY(so->so_msg_state != NULL);
	VERIFY(sb->sb_flags & SB_RECV);

	/* Keep the TCP sequence number in the mbuf pkthdr */
	m->m_pkthdr.msg_seq = seqnum;

	/* find last mbuf and set M_EOR */
	for (m_eor = m; ; m_eor = m_eor->m_next) {
		/*
		 * If the msg is unordered, we need to account for
		 * these bytes in receive socket buffer size. Otherwise,
		 * the receive window advertised will shrink because
		 * of the additional unordered bytes added to the
		 * receive buffer.
		 */
		if (unordered) {
			m_eor->m_flags |= M_UNORDERED_DATA;
			data_len += m_eor->m_len;
			so->so_msg_state->msg_uno_bytes += m_eor->m_len;
		} else {
			m_eor->m_flags &= ~M_UNORDERED_DATA;
		}
		if (m_eor->m_next == NULL)
			break;
	}

	/* set EOR flag at end of byte blob */
	m_eor->m_flags |= M_EOR;

	/* expand the receive socket buffer to allow unordered data */
	if (unordered && !sbreserve(sb, sb->sb_hiwat + data_len)) {
		/*
		 * Could not allocate memory for unordered data, it
		 * means this packet will have to be delivered in order
		 */
		printf("%s: could not reserve space for unordered data\n",
		    __func__);
	}

	if (!unordered && (sb->sb_mbtail != NULL) &&
		!(sb->sb_mbtail->m_flags & M_UNORDERED_DATA)) {
		sb->sb_mbtail->m_flags &= ~M_EOR;
		sbcompress(sb, m, sb->sb_mbtail);
		ret = 1;
	} else {
		ret = sbappendrecord(sb, m);
	}
	VERIFY(sb->sb_mbtail->m_flags & M_EOR);
	return (ret);
}

/*
 * TCP streams have message based out of order delivery support, or have
 * Multipath TCP support, or are regular TCP sockets
 */
int
sbappendstream_rcvdemux(struct socket *so, struct mbuf *m, uint32_t seqnum,
	int unordered)
{
	int ret = 0;

	if ((m != NULL) && (m_pktlen(m) <= 0)) {
		m_freem(m);
		return (ret);
	}

	if (so->so_flags & SOF_ENABLE_MSGS) {
		ret = sbappendmsgstream_rcv(&so->so_rcv, m, seqnum, unordered);
	}
#if MPTCP
	else if (so->so_flags & SOF_MPTCP_TRUE) {
		ret = sbappendmptcpstream_rcv(&so->so_rcv, m);
	}
#endif /* MPTCP */
	else {
		ret = sbappendstream(&so->so_rcv, m);
	}
	return (ret);
}

#if MPTCP
int
sbappendmptcpstream_rcv(struct sockbuf *sb, struct mbuf *m)
{
	struct socket *so = sb->sb_so;

	VERIFY(m == NULL || (m->m_flags & M_PKTHDR));
	/* SB_NOCOMPRESS must be set prevent loss of M_PKTHDR data */
	VERIFY((sb->sb_flags & (SB_RECV|SB_NOCOMPRESS)) ==
	    (SB_RECV|SB_NOCOMPRESS));

	if (m == NULL || m_pktlen(m) == 0 || (sb->sb_flags & SB_DROP) ||
	    (so->so_state & SS_CANTRCVMORE)) {
		if (m != NULL)
			m_freem(m);
		return (0);
	}
	/* the socket is not closed, so SOF_MP_SUBFLOW must be set */
	VERIFY(so->so_flags & SOF_MP_SUBFLOW);

	if (m->m_nextpkt != NULL || (sb->sb_mb != sb->sb_lastrecord)) {
		panic("%s: nexpkt %p || mb %p != lastrecord %p\n", __func__,
		    m->m_nextpkt, sb->sb_mb, sb->sb_lastrecord);
		/* NOTREACHED */
	}

	SBLASTMBUFCHK(sb, __func__);

	if (mptcp_adj_rmap(so, m) != 0)
		return (0);

	/* No filter support (SB_RECV) on mptcp subflow sockets */

	sbcompress(sb, m, sb->sb_mbtail);
	sb->sb_lastrecord = sb->sb_mb;
	SBLASTRECORDCHK(sb, __func__);
	return (1);
}
#endif /* MPTCP */

/*
 * Append message to send socket buffer based on priority.
 */
int
sbappendmsg_snd(struct sockbuf *sb, struct mbuf *m)
{
	struct socket *so = sb->sb_so;
	struct msg_priq *priq;
	int set_eor = 0;

	VERIFY(so->so_msg_state != NULL);

	if (m->m_nextpkt != NULL || (sb->sb_mb != sb->sb_lastrecord))
		panic("sbappendstream: nexpkt %p || mb %p != lastrecord %p\n",
		    m->m_nextpkt, sb->sb_mb, sb->sb_lastrecord);

	SBLASTMBUFCHK(sb, __func__);

	if (m == NULL || (sb->sb_flags & SB_DROP) || so->so_msg_state == NULL) {
		if (m != NULL)
			m_freem(m);
		return (0);
	}

	priq = &so->so_msg_state->msg_priq[m->m_pkthdr.msg_pri];

	/* note if we need to propogate M_EOR to the last mbuf */
	if (m->m_flags & M_EOR) {
		set_eor = 1;

		/* Reset M_EOR from the first mbuf */
		m->m_flags &= ~(M_EOR);
	}

	if (priq->msgq_head == NULL) {
		VERIFY(priq->msgq_tail == NULL && priq->msgq_lastmsg == NULL);
		priq->msgq_head = priq->msgq_lastmsg = m;
	} else {
		VERIFY(priq->msgq_tail->m_next == NULL);

		/* Check if the last message has M_EOR flag set */
		if (priq->msgq_tail->m_flags & M_EOR) {
			/* Insert as a new message */
			priq->msgq_lastmsg->m_nextpkt = m;

			/* move the lastmsg pointer */
			priq->msgq_lastmsg = m;
		} else {
			/* Append to the existing message */
			priq->msgq_tail->m_next = m;
		}
	}

	/* Update accounting and the queue tail pointer */

	while (m->m_next != NULL) {
		sballoc(sb, m);
		priq->msgq_bytes += m->m_len;
		m = m->m_next;
	}
	sballoc(sb, m);
	priq->msgq_bytes += m->m_len;

	if (set_eor) {
		m->m_flags |= M_EOR;

		/*
		 * Since the user space can not write a new msg
		 * without completing the previous one, we can
		 * reset this flag to start sending again.
		 */
		priq->msgq_flags &= ~(MSGQ_MSG_NOTDONE);
	}

	priq->msgq_tail = m;

	SBLASTRECORDCHK(sb, "sbappendstream 2");
	postevent(0, sb, EV_RWBYTES);
	return (1);
}

/*
 * Pull data from priority queues to the serial snd queue
 * right before sending.
 */
void
sbpull_unordered_data(struct socket *so, int32_t off, int32_t len)
{
	int32_t topull, i;
	struct msg_priq *priq = NULL;

	VERIFY(so->so_msg_state != NULL);

	topull = (off + len) - so->so_msg_state->msg_serial_bytes;

	i = MSG_PRI_MAX;
	while (i >= MSG_PRI_MIN && topull > 0) {
		struct mbuf *m = NULL, *mqhead = NULL, *mend = NULL;
		priq = &so->so_msg_state->msg_priq[i];
		if ((priq->msgq_flags & MSGQ_MSG_NOTDONE) &&
		    priq->msgq_head == NULL) {
			/*
			 * We were in the middle of sending
			 * a message and we have not seen the
			 * end of it.
			 */
			VERIFY(priq->msgq_lastmsg == NULL &&
			    priq->msgq_tail == NULL);
			return;
		}
		if (priq->msgq_head != NULL) {
			int32_t bytes = 0, topull_tmp = topull;
			/*
			 * We found a msg while scanning the priority
			 * queue from high to low priority.
			 */
			m = priq->msgq_head;
			mqhead = m;
			mend = m;

			/*
			 * Move bytes from the priority queue to the
			 * serial queue. Compute the number of bytes
			 * being added.
			 */
			while (mqhead->m_next != NULL && topull_tmp > 0) {
				bytes += mqhead->m_len;
				topull_tmp -= mqhead->m_len;
				mend = mqhead;
				mqhead = mqhead->m_next;
			}

			if (mqhead->m_next == NULL) {
				/*
				 * If we have only one more mbuf left,
				 * move the last mbuf of this message to
				 * serial queue and set the head of the
				 * queue to be the next message.
				 */
				bytes += mqhead->m_len;
				mend = mqhead;
				mqhead = m->m_nextpkt;
				if (!(mend->m_flags & M_EOR)) {
					/*
					 * We have not seen the end of
					 * this message, so we can not
					 * pull anymore.
					 */
					priq->msgq_flags |= MSGQ_MSG_NOTDONE;
				} else {
					/* Reset M_EOR */
					mend->m_flags &= ~(M_EOR);
				}
			} else {
				/* propogate the next msg pointer */
				mqhead->m_nextpkt = m->m_nextpkt;
			}
			priq->msgq_head = mqhead;

			/*
			 * if the lastmsg pointer points to
			 * the mbuf that is being dequeued, update
			 * it to point to the new head.
			 */
			if (priq->msgq_lastmsg == m)
				priq->msgq_lastmsg = priq->msgq_head;

			m->m_nextpkt = NULL;
			mend->m_next = NULL;

			if (priq->msgq_head == NULL) {
				/* Moved all messages, update tail */
				priq->msgq_tail = NULL;
				VERIFY(priq->msgq_lastmsg == NULL);
			}

			/* Move it to serial sb_mb queue */
			if (so->so_snd.sb_mb == NULL) {
				so->so_snd.sb_mb = m;
			} else {
				so->so_snd.sb_mbtail->m_next = m;
			}

			priq->msgq_bytes -= bytes;
			VERIFY(priq->msgq_bytes >= 0);
			sbwakeup(&so->so_snd);

			so->so_msg_state->msg_serial_bytes += bytes;
			so->so_snd.sb_mbtail = mend;
			so->so_snd.sb_lastrecord = so->so_snd.sb_mb;

			topull =
			    (off + len) - so->so_msg_state->msg_serial_bytes;

			if (priq->msgq_flags & MSGQ_MSG_NOTDONE)
				break;
		} else {
			--i;
		}
	}
	sblastrecordchk(&so->so_snd, "sbpull_unordered_data");
	sblastmbufchk(&so->so_snd, "sbpull_unordered_data");
}

/*
 * Compress mbuf chain m into the socket
 * buffer sb following mbuf n.  If n
 * is null, the buffer is presumed empty.
 */
static inline void
sbcompress(struct sockbuf *sb, struct mbuf *m, struct mbuf *n)
{
	int eor = 0, compress = (!(sb->sb_flags & SB_NOCOMPRESS));
	struct mbuf *o;

	if (m == NULL) {
		/* There is nothing to compress; just update the tail */
		for (; n->m_next != NULL; n = n->m_next)
			;
		sb->sb_mbtail = n;
		goto done;
	}

	while (m != NULL) {
		eor |= m->m_flags & M_EOR;
		if (compress && m->m_len == 0 && (eor == 0 ||
		    (((o = m->m_next) || (o = n)) && o->m_type == m->m_type))) {
			if (sb->sb_lastrecord == m)
				sb->sb_lastrecord = m->m_next;
			m = m_free(m);
			continue;
		}
		if (compress && n != NULL && (n->m_flags & M_EOR) == 0 &&
#ifndef __APPLE__
		    M_WRITABLE(n) &&
#endif
		    m->m_len <= MCLBYTES / 4 && /* XXX: Don't copy too much */
		    m->m_len <= M_TRAILINGSPACE(n) &&
		    n->m_type == m->m_type) {
			bcopy(mtod(m, caddr_t), mtod(n, caddr_t) + n->m_len,
			    (unsigned)m->m_len);
			n->m_len += m->m_len;
			sb->sb_cc += m->m_len;
			if (m->m_type != MT_DATA && m->m_type != MT_HEADER &&
			    m->m_type != MT_OOBDATA) {
				/* XXX: Probably don't need */
				sb->sb_ctl += m->m_len;
			}
			m = m_free(m);
			continue;
		}
		if (n != NULL)
			n->m_next = m;
		else
			sb->sb_mb = m;
		sb->sb_mbtail = m;
		sballoc(sb, m);
		n = m;
		m->m_flags &= ~M_EOR;
		m = m->m_next;
		n->m_next = NULL;
	}
	if (eor != 0) {
		if (n != NULL)
			n->m_flags |= eor;
		else
			printf("semi-panic: sbcompress\n");
	}
done:
	SBLASTMBUFCHK(sb, __func__);
	postevent(0, sb, EV_RWBYTES);
}

void
sb_empty_assert(struct sockbuf *sb, const char *where)
{
	if (!(sb->sb_cc == 0 && sb->sb_mb == NULL && sb->sb_mbcnt == 0 &&
	    sb->sb_mbtail == NULL && sb->sb_lastrecord == NULL)) {
		panic("%s: sb %p so %p cc %d mbcnt %d mb %p mbtail %p "
		    "lastrecord %p\n", where, sb, sb->sb_so, sb->sb_cc,
		    sb->sb_mbcnt, sb->sb_mb, sb->sb_mbtail,
		    sb->sb_lastrecord);
		/* NOTREACHED */
	}
}

static void
sbflush_priq(struct msg_priq *priq)
{
	struct mbuf *m;
	m = priq->msgq_head;
	if (m != NULL)
		m_freem_list(m);
	priq->msgq_head = priq->msgq_tail = priq->msgq_lastmsg = NULL;
	priq->msgq_bytes = priq->msgq_flags = 0;
}

/*
 * Free all mbufs in a sockbuf.
 * Check that all resources are reclaimed.
 */
void
sbflush(struct sockbuf *sb)
{
	void *lr_saved = __builtin_return_address(0);
	struct socket *so = sb->sb_so;
#ifdef notyet
	lck_mtx_t *mutex_held;
#endif
	u_int32_t i;

	/* so_usecount may be 0 if we get here from sofreelastref() */
	if (so == NULL) {
		panic("%s: null so, sb=%p sb_flags=0x%x lr=%p\n",
		    __func__, sb, sb->sb_flags, lr_saved);
		/* NOTREACHED */
	} else if (so->so_usecount < 0) {
		panic("%s: sb=%p sb_flags=0x%x sb_so=%p usecount=%d lr=%p "
		    "lrh= %s\n", __func__, sb, sb->sb_flags, so,
		    so->so_usecount, lr_saved, solockhistory_nr(so));
		/* NOTREACHED */
	}
#ifdef notyet
	/*
	 * XXX: This code is currently commented out, because we may get here
	 * as part of sofreelastref(), and at that time, pr_getlock() may no
	 * longer be able to return us the lock; this will be fixed in future.
	 */
	if (so->so_proto->pr_getlock != NULL)
		mutex_held = (*so->so_proto->pr_getlock)(so, 0);
	else
		mutex_held = so->so_proto->pr_domain->dom_mtx;

	lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);
#endif

	/*
	 * Obtain lock on the socket buffer (SB_LOCK).  This is required
	 * to prevent the socket buffer from being unexpectedly altered
	 * while it is used by another thread in socket send/receive.
	 *
	 * sblock() must not fail here, hence the assertion.
	 */
	(void) sblock(sb, SBL_WAIT | SBL_NOINTR | SBL_IGNDEFUNCT);
	VERIFY(sb->sb_flags & SB_LOCK);

	while (sb->sb_mbcnt > 0) {
		/*
		 * Don't call sbdrop(sb, 0) if the leading mbuf is non-empty:
		 * we would loop forever. Panic instead.
		 */
		if (!sb->sb_cc && (sb->sb_mb == NULL || sb->sb_mb->m_len))
			break;
		sbdrop(sb, (int)sb->sb_cc);
	}

	if (!(sb->sb_flags & SB_RECV) && (so->so_flags & SOF_ENABLE_MSGS)) {
		VERIFY(so->so_msg_state != NULL);
		for (i = MSG_PRI_MIN; i <= MSG_PRI_MAX; ++i) {
			sbflush_priq(&so->so_msg_state->msg_priq[i]);
		}
		so->so_msg_state->msg_serial_bytes = 0;
		so->so_msg_state->msg_uno_bytes = 0;
	}

	sb_empty_assert(sb, __func__);
	postevent(0, sb, EV_RWBYTES);

	sbunlock(sb, TRUE);	/* keep socket locked */
}

/*
 * Drop data from (the front of) a sockbuf.
 * use m_freem_list to free the mbuf structures
 * under a single lock... this is done by pruning
 * the top of the tree from the body by keeping track
 * of where we get to in the tree and then zeroing the
 * two pertinent pointers m_nextpkt and m_next
 * the socket buffer is then updated to point at the new
 * top of the tree and the pruned area is released via
 * m_freem_list.
 */
void
sbdrop(struct sockbuf *sb, int len)
{
	struct mbuf *m, *free_list, *ml;
	struct mbuf *next, *last;

	next = (m = sb->sb_mb) ? m->m_nextpkt : 0;
#if MPTCP
	if ((m != NULL) && (len > 0) &&
	    (!(sb->sb_flags & SB_RECV)) &&
	    ((sb->sb_so->so_flags & SOF_MP_SUBFLOW) ||
	    ((SOCK_CHECK_DOM(sb->sb_so, PF_MULTIPATH)) &&
	    (SOCK_CHECK_PROTO(sb->sb_so, IPPROTO_TCP)))) &&
	    (!(sb->sb_so->so_flags1 & SOF1_POST_FALLBACK_SYNC))) {
		mptcp_preproc_sbdrop(m, (unsigned int)len);
	}
#endif /* MPTCP */
	KERNEL_DEBUG((DBG_FNC_SBDROP | DBG_FUNC_START), sb, len, 0, 0, 0);

	free_list = last = m;
	ml = (struct mbuf *)0;

	while (len > 0) {
		if (m == 0) {
			if (next == 0) {
				/*
				 * temporarily replacing this panic with printf
				 * because it occurs occasionally when closing
				 * a socket when there is no harm in ignoring
				 * it. This problem will be investigated
				 * further.
				 */
				/* panic("sbdrop"); */
				printf("sbdrop - count not zero\n");
				len = 0;
				/*
				 * zero the counts. if we have no mbufs,
				 * we have no data (PR-2986815)
				 */
				sb->sb_cc = 0;
				sb->sb_mbcnt = 0;
				if (!(sb->sb_flags & SB_RECV) &&
				    (sb->sb_so->so_flags & SOF_ENABLE_MSGS)) {
					sb->sb_so->so_msg_state->
					    msg_serial_bytes = 0;
				}
				break;
			}
			m = last = next;
			next = m->m_nextpkt;
			continue;
		}
		if (m->m_len > len) {
			m->m_len -= len;
			m->m_data += len;
			sb->sb_cc -= len;
			if (m->m_type != MT_DATA && m->m_type != MT_HEADER &&
			    m->m_type != MT_OOBDATA)
				sb->sb_ctl -= len;
			break;
		}
		len -= m->m_len;
		sbfree(sb, m);

		ml = m;
		m = m->m_next;
	}
	while (m && m->m_len == 0) {
		sbfree(sb, m);

		ml = m;
		m = m->m_next;
	}
	if (ml) {
		ml->m_next = (struct mbuf *)0;
		last->m_nextpkt = (struct mbuf *)0;
		m_freem_list(free_list);
	}
	if (m) {
		sb->sb_mb = m;
		m->m_nextpkt = next;
	} else {
		sb->sb_mb = next;
	}

	/*
	 * First part is an inline SB_EMPTY_FIXUP().  Second part
	 * makes sure sb_lastrecord is up-to-date if we dropped
	 * part of the last record.
	 */
	m = sb->sb_mb;
	if (m == NULL) {
		sb->sb_mbtail = NULL;
		sb->sb_lastrecord = NULL;
	} else if (m->m_nextpkt == NULL) {
		sb->sb_lastrecord = m;
	}

#if CONTENT_FILTER
	cfil_sock_buf_update(sb);
#endif /* CONTENT_FILTER */

	postevent(0, sb, EV_RWBYTES);

	KERNEL_DEBUG((DBG_FNC_SBDROP | DBG_FUNC_END), sb, 0, 0, 0, 0);
}

/*
 * Drop a record off the front of a sockbuf
 * and move the next record to the front.
 */
void
sbdroprecord(struct sockbuf *sb)
{
	struct mbuf *m, *mn;

	m = sb->sb_mb;
	if (m) {
		sb->sb_mb = m->m_nextpkt;
		do {
			sbfree(sb, m);
			MFREE(m, mn);
			m = mn;
		} while (m);
	}
	SB_EMPTY_FIXUP(sb);
	postevent(0, sb, EV_RWBYTES);
}

/*
 * Create a "control" mbuf containing the specified data
 * with the specified type for presentation on a socket buffer.
 */
struct mbuf *
sbcreatecontrol(caddr_t p, int size, int type, int level)
{
	struct cmsghdr *cp;
	struct mbuf *m;

	if (CMSG_SPACE((u_int)size) > MLEN)
		return ((struct mbuf *)NULL);
	if ((m = m_get(M_DONTWAIT, MT_CONTROL)) == NULL)
		return ((struct mbuf *)NULL);
	cp = mtod(m, struct cmsghdr *);
	VERIFY(IS_P2ALIGNED(cp, sizeof (u_int32_t)));
	/* XXX check size? */
	(void) memcpy(CMSG_DATA(cp), p, size);
	m->m_len = CMSG_SPACE(size);
	cp->cmsg_len = CMSG_LEN(size);
	cp->cmsg_level = level;
	cp->cmsg_type = type;
	return (m);
}

struct mbuf **
sbcreatecontrol_mbuf(caddr_t p, int size, int type, int level, struct mbuf **mp)
{
	struct mbuf *m;
	struct cmsghdr *cp;

	if (*mp == NULL) {
		*mp = sbcreatecontrol(p, size, type, level);
		return (mp);
	}

	if (CMSG_SPACE((u_int)size) + (*mp)->m_len > MLEN) {
		mp = &(*mp)->m_next;
		*mp = sbcreatecontrol(p, size, type, level);
		return (mp);
	}

	m = *mp;

	cp = (struct cmsghdr *)(void *)(mtod(m, char *) + m->m_len);
	/* CMSG_SPACE ensures 32-bit alignment */
	VERIFY(IS_P2ALIGNED(cp, sizeof (u_int32_t)));
	m->m_len += CMSG_SPACE(size);

	/* XXX check size? */
	(void) memcpy(CMSG_DATA(cp), p, size);
	cp->cmsg_len = CMSG_LEN(size);
	cp->cmsg_level = level;
	cp->cmsg_type = type;

	return (mp);
}


/*
 * Some routines that return EOPNOTSUPP for entry points that are not
 * supported by a protocol.  Fill in as needed.
 */
int
pru_abort_notsupp(struct socket *so)
{
#pragma unused(so)
	return (EOPNOTSUPP);
}

int
pru_accept_notsupp(struct socket *so, struct sockaddr **nam)
{
#pragma unused(so, nam)
	return (EOPNOTSUPP);
}

int
pru_attach_notsupp(struct socket *so, int proto, struct proc *p)
{
#pragma unused(so, proto, p)
	return (EOPNOTSUPP);
}

int
pru_bind_notsupp(struct socket *so, struct sockaddr *nam, struct proc *p)
{
#pragma unused(so, nam, p)
	return (EOPNOTSUPP);
}

int
pru_connect_notsupp(struct socket *so, struct sockaddr *nam, struct proc *p)
{
#pragma unused(so, nam, p)
	return (EOPNOTSUPP);
}

int
pru_connect2_notsupp(struct socket *so1, struct socket *so2)
{
#pragma unused(so1, so2)
	return (EOPNOTSUPP);
}

int
pru_connectx_notsupp(struct socket *so, struct sockaddr_list **src_sl,
    struct sockaddr_list **dst_sl, struct proc *p, uint32_t ifscope,
    sae_associd_t aid, sae_connid_t *pcid, uint32_t flags, void *arg,
    uint32_t arglen, struct uio *uio, user_ssize_t *bytes_written)
{
#pragma unused(so, src_sl, dst_sl, p, ifscope, aid, pcid, flags, arg, arglen, uio, bytes_written)
	return (EOPNOTSUPP);
}

int
pru_control_notsupp(struct socket *so, u_long cmd, caddr_t data,
    struct ifnet *ifp, struct proc *p)
{
#pragma unused(so, cmd, data, ifp, p)
	return (EOPNOTSUPP);
}

int
pru_detach_notsupp(struct socket *so)
{
#pragma unused(so)
	return (EOPNOTSUPP);
}

int
pru_disconnect_notsupp(struct socket *so)
{
#pragma unused(so)
	return (EOPNOTSUPP);
}

int
pru_disconnectx_notsupp(struct socket *so, sae_associd_t aid, sae_connid_t cid)
{
#pragma unused(so, aid, cid)
	return (EOPNOTSUPP);
}

int
pru_listen_notsupp(struct socket *so, struct proc *p)
{
#pragma unused(so, p)
	return (EOPNOTSUPP);
}

int
pru_peeloff_notsupp(struct socket *so, sae_associd_t aid, struct socket **psop)
{
#pragma unused(so, aid, psop)
	return (EOPNOTSUPP);
}

int
pru_peeraddr_notsupp(struct socket *so, struct sockaddr **nam)
{
#pragma unused(so, nam)
	return (EOPNOTSUPP);
}

int
pru_rcvd_notsupp(struct socket *so, int flags)
{
#pragma unused(so, flags)
	return (EOPNOTSUPP);
}

int
pru_rcvoob_notsupp(struct socket *so, struct mbuf *m, int flags)
{
#pragma unused(so, m, flags)
	return (EOPNOTSUPP);
}

int
pru_send_notsupp(struct socket *so, int flags, struct mbuf *m,
    struct sockaddr *addr, struct mbuf *control, struct proc *p)
{
#pragma unused(so, flags, m, addr, control, p)
	return (EOPNOTSUPP);
}

int
pru_send_list_notsupp(struct socket *so, int flags, struct mbuf *m,
    struct sockaddr *addr, struct mbuf *control, struct proc *p)
{
#pragma unused(so, flags, m, addr, control, p)
	return (EOPNOTSUPP);
}

/*
 * This isn't really a ``null'' operation, but it's the default one
 * and doesn't do anything destructive.
 */
int
pru_sense_null(struct socket *so, void *ub, int isstat64)
{
	if (isstat64 != 0) {
		struct stat64 *sb64;

		sb64 = (struct stat64 *)ub;
		sb64->st_blksize = so->so_snd.sb_hiwat;
	} else {
		struct stat *sb;

		sb = (struct stat *)ub;
		sb->st_blksize = so->so_snd.sb_hiwat;
	}

	return (0);
}


int
pru_sosend_notsupp(struct socket *so, struct sockaddr *addr, struct uio *uio,
    struct mbuf *top, struct mbuf *control, int flags)
{
#pragma unused(so, addr, uio, top, control, flags)
	return (EOPNOTSUPP);
}

int
pru_sosend_list_notsupp(struct socket *so, struct uio **uio,
    u_int uiocnt, int flags)
{
#pragma unused(so, uio, uiocnt, flags)
	return (EOPNOTSUPP);
}

int
pru_soreceive_notsupp(struct socket *so, struct sockaddr **paddr,
    struct uio *uio, struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
{
#pragma unused(so, paddr, uio, mp0, controlp, flagsp)
	return (EOPNOTSUPP);
}

int
pru_soreceive_list_notsupp(struct socket *so, 
    struct recv_msg_elem *recv_msg_array, u_int uiocnt, int *flagsp)
{
#pragma unused(so, recv_msg_array, uiocnt, flagsp)
	return (EOPNOTSUPP);
}

int
pru_shutdown_notsupp(struct socket *so)
{
#pragma unused(so)
	return (EOPNOTSUPP);
}

int
pru_sockaddr_notsupp(struct socket *so, struct sockaddr **nam)
{
#pragma unused(so, nam)
	return (EOPNOTSUPP);
}

int
pru_sopoll_notsupp(struct socket *so, int events, kauth_cred_t cred, void *wql)
{
#pragma unused(so, events, cred, wql)
	return (EOPNOTSUPP);
}

int
pru_socheckopt_null(struct socket *so, struct sockopt *sopt)
{
#pragma unused(so, sopt)
	/*
	 * Allow all options for set/get by default.
	 */
	return (0);
}

static int
pru_preconnect_null(struct socket *so)
{
#pragma unused(so)
	return (0);
}

void
pru_sanitize(struct pr_usrreqs *pru)
{
#define	DEFAULT(foo, bar)	if ((foo) == NULL) (foo) = (bar)
	DEFAULT(pru->pru_abort, pru_abort_notsupp);
	DEFAULT(pru->pru_accept, pru_accept_notsupp);
	DEFAULT(pru->pru_attach, pru_attach_notsupp);
	DEFAULT(pru->pru_bind, pru_bind_notsupp);
	DEFAULT(pru->pru_connect, pru_connect_notsupp);
	DEFAULT(pru->pru_connect2, pru_connect2_notsupp);
	DEFAULT(pru->pru_connectx, pru_connectx_notsupp);
	DEFAULT(pru->pru_control, pru_control_notsupp);
	DEFAULT(pru->pru_detach, pru_detach_notsupp);
	DEFAULT(pru->pru_disconnect, pru_disconnect_notsupp);
	DEFAULT(pru->pru_disconnectx, pru_disconnectx_notsupp);
	DEFAULT(pru->pru_listen, pru_listen_notsupp);
	DEFAULT(pru->pru_peeloff, pru_peeloff_notsupp);
	DEFAULT(pru->pru_peeraddr, pru_peeraddr_notsupp);
	DEFAULT(pru->pru_rcvd, pru_rcvd_notsupp);
	DEFAULT(pru->pru_rcvoob, pru_rcvoob_notsupp);
	DEFAULT(pru->pru_send, pru_send_notsupp);
	DEFAULT(pru->pru_send_list, pru_send_list_notsupp);
	DEFAULT(pru->pru_sense, pru_sense_null);
	DEFAULT(pru->pru_shutdown, pru_shutdown_notsupp);
	DEFAULT(pru->pru_sockaddr, pru_sockaddr_notsupp);
	DEFAULT(pru->pru_sopoll, pru_sopoll_notsupp);
	DEFAULT(pru->pru_soreceive, pru_soreceive_notsupp);
	DEFAULT(pru->pru_soreceive_list, pru_soreceive_list_notsupp);
	DEFAULT(pru->pru_sosend, pru_sosend_notsupp);
	DEFAULT(pru->pru_sosend_list, pru_sosend_list_notsupp);
	DEFAULT(pru->pru_socheckopt, pru_socheckopt_null);
	DEFAULT(pru->pru_preconnect, pru_preconnect_null);
#undef DEFAULT
}

/*
 * The following are macros on BSD and functions on Darwin
 */

/*
 * Do we need to notify the other side when I/O is possible?
 */

int
sb_notify(struct sockbuf *sb)
{
	return (sb->sb_waiters > 0 ||
	    (sb->sb_flags & (SB_SEL|SB_ASYNC|SB_UPCALL|SB_KNOTE)));
}

/*
 * How much space is there in a socket buffer (so->so_snd or so->so_rcv)?
 * This is problematical if the fields are unsigned, as the space might
 * still be negative (cc > hiwat or mbcnt > mbmax).  Should detect
 * overflow and return 0.
 */
int
sbspace(struct sockbuf *sb)
{
	int pending = 0;
	int space = imin((int)(sb->sb_hiwat - sb->sb_cc),
	    (int)(sb->sb_mbmax - sb->sb_mbcnt));

	if (sb->sb_preconn_hiwat != 0)
		space = imin((int)(sb->sb_preconn_hiwat - sb->sb_cc), space);

	if (space < 0)
		space = 0;

	/* Compensate for data being processed by content filters */
#if CONTENT_FILTER
	pending = cfil_sock_data_space(sb);
#endif /* CONTENT_FILTER */
	if (pending > space)
		space = 0;
	else
		space -= pending;

	return (space);
}

/*
 * If this socket has priority queues, check if there is enough
 * space in the priority queue for this msg.
 */
int
msgq_sbspace(struct socket *so, struct mbuf *control)
{
	int space = 0, error;
	u_int32_t msgpri;
	VERIFY(so->so_type == SOCK_STREAM &&
		SOCK_PROTO(so) == IPPROTO_TCP);
	if (control != NULL) {
		error = tcp_get_msg_priority(control, &msgpri);
		if (error)
			return (0);
	} else {
		msgpri = MSG_PRI_0;
	}
	space = (so->so_snd.sb_idealsize / MSG_PRI_COUNT) -
	    so->so_msg_state->msg_priq[msgpri].msgq_bytes;
	if (space < 0)
		space = 0;
	return (space);
}

/* do we have to send all at once on a socket? */
int
sosendallatonce(struct socket *so)
{
	return (so->so_proto->pr_flags & PR_ATOMIC);
}

/* can we read something from so? */
int
soreadable(struct socket *so)
{
	return (so->so_rcv.sb_cc >= so->so_rcv.sb_lowat ||
	    ((so->so_state & SS_CANTRCVMORE)
#if CONTENT_FILTER
	    && cfil_sock_data_pending(&so->so_rcv) == 0
#endif /* CONTENT_FILTER */
	    ) ||
	    so->so_comp.tqh_first || so->so_error);
}

/* can we write something to so? */

int
sowriteable(struct socket *so)
{
	if ((so->so_state & SS_CANTSENDMORE) ||
	    so->so_error > 0)
		return (1);
	if (so_wait_for_if_feedback(so) || !socanwrite(so))
		return (0);
	if (so->so_flags1 & SOF1_PRECONNECT_DATA)
		return(1);

	if (sbspace(&(so)->so_snd) >= (so)->so_snd.sb_lowat) {
		if (so->so_flags & SOF_NOTSENT_LOWAT) {
			if ((SOCK_DOM(so) == PF_INET6 ||
			    SOCK_DOM(so) == PF_INET) &&
			    so->so_type == SOCK_STREAM) {
				return (tcp_notsent_lowat_check(so));
			}
#if MPTCP
			else if ((SOCK_DOM(so) == PF_MULTIPATH) &&
			    (SOCK_PROTO(so) == IPPROTO_TCP)) {
				return (mptcp_notsent_lowat_check(so));
			}
#endif
			else {
				return (1);
			}
		} else {
			return (1);
		}
	}
	return (0);
}

/* adjust counters in sb reflecting allocation of m */

void
sballoc(struct sockbuf *sb, struct mbuf *m)
{
	u_int32_t cnt = 1;
	sb->sb_cc += m->m_len;
	if (m->m_type != MT_DATA && m->m_type != MT_HEADER &&
	    m->m_type != MT_OOBDATA)
		sb->sb_ctl += m->m_len;
	sb->sb_mbcnt += MSIZE;

	if (m->m_flags & M_EXT) {
		sb->sb_mbcnt += m->m_ext.ext_size;
		cnt += (m->m_ext.ext_size >> MSIZESHIFT);
	}
	OSAddAtomic(cnt, &total_sbmb_cnt);
	VERIFY(total_sbmb_cnt > 0);
	if (total_sbmb_cnt > total_sbmb_cnt_peak)
		total_sbmb_cnt_peak = total_sbmb_cnt;

	/*
	 * If data is being appended to the send socket buffer,
	 * update the send byte count
	 */
	if (!(sb->sb_flags & SB_RECV))
		OSAddAtomic(cnt, &total_snd_byte_count);
}

/* adjust counters in sb reflecting freeing of m */
void
sbfree(struct sockbuf *sb, struct mbuf *m)
{
	int cnt = -1;

	sb->sb_cc -= m->m_len;
	if (m->m_type != MT_DATA && m->m_type != MT_HEADER &&
	    m->m_type != MT_OOBDATA)
		sb->sb_ctl -= m->m_len;
	sb->sb_mbcnt -= MSIZE;
	if (m->m_flags & M_EXT) {
		sb->sb_mbcnt -= m->m_ext.ext_size;
		cnt -= (m->m_ext.ext_size >> MSIZESHIFT);
	}
	OSAddAtomic(cnt, &total_sbmb_cnt);
	VERIFY(total_sbmb_cnt >= 0);

	/*
	 * If data is being removed from the send socket buffer,
	 * update the send byte count
	 */
	if (!(sb->sb_flags & SB_RECV)) {
		OSAddAtomic(cnt, &total_snd_byte_count);
	}
}

/*
 * Set lock on sockbuf sb; sleep if lock is already held.
 * Unless SB_NOINTR is set on sockbuf, sleep is interruptible.
 * Returns error without lock if sleep is interrupted.
 */
int
sblock(struct sockbuf *sb, uint32_t flags)
{
	boolean_t nointr = ((sb->sb_flags & SB_NOINTR) || (flags & SBL_NOINTR));
	void *lr_saved = __builtin_return_address(0);
	struct socket *so = sb->sb_so;
	void * wchan;
	int error = 0;
	thread_t tp = current_thread();

	VERIFY((flags & SBL_VALID) == flags);

	/* so_usecount may be 0 if we get here from sofreelastref() */
	if (so == NULL) {
		panic("%s: null so, sb=%p sb_flags=0x%x lr=%p\n",
		    __func__, sb, sb->sb_flags, lr_saved);
		/* NOTREACHED */
	} else if (so->so_usecount < 0) {
		panic("%s: sb=%p sb_flags=0x%x sb_so=%p usecount=%d lr=%p "
		    "lrh= %s\n", __func__, sb, sb->sb_flags, so,
		    so->so_usecount, lr_saved, solockhistory_nr(so));
		/* NOTREACHED */
	}

	/*
	 * The content filter thread must hold the sockbuf lock
	 */
	if ((so->so_flags & SOF_CONTENT_FILTER) && sb->sb_cfil_thread == tp) {
		/*
		 * Don't panic if we are defunct because SB_LOCK has
		 * been cleared by sodefunct()
		 */
		if (!(so->so_flags & SOF_DEFUNCT) && !(sb->sb_flags & SB_LOCK))
			panic("%s: SB_LOCK not held for %p\n",
			    __func__, sb);

		/* Keep the sockbuf locked */
		return (0);
	}

	if ((sb->sb_flags & SB_LOCK) && !(flags & SBL_WAIT))
		return (EWOULDBLOCK);
	/*
	 * We may get here from sorflush(), in which case "sb" may not
	 * point to the real socket buffer.  Use the actual socket buffer
	 * address from the socket instead.
	 */
	wchan = (sb->sb_flags & SB_RECV) ?
	    &so->so_rcv.sb_flags : &so->so_snd.sb_flags;

	/*
	 * A content filter thread has exclusive access to the sockbuf
	 * until it clears the
	 */
	while ((sb->sb_flags & SB_LOCK) ||
		((so->so_flags & SOF_CONTENT_FILTER) &&
		sb->sb_cfil_thread != NULL)) {
		lck_mtx_t *mutex_held;

		/*
		 * XXX: This code should be moved up above outside of this loop;
		 * however, we may get here as part of sofreelastref(), and
		 * at that time pr_getlock() may no longer be able to return
		 * us the lock.  This will be fixed in future.
		 */
		if (so->so_proto->pr_getlock != NULL)
			mutex_held = (*so->so_proto->pr_getlock)(so, 0);
		else
			mutex_held = so->so_proto->pr_domain->dom_mtx;

		lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

		sb->sb_wantlock++;
		VERIFY(sb->sb_wantlock != 0);

		error = msleep(wchan, mutex_held,
		    nointr ? PSOCK : PSOCK | PCATCH,
		    nointr ? "sb_lock_nointr" : "sb_lock", NULL);

		VERIFY(sb->sb_wantlock != 0);
		sb->sb_wantlock--;

		if (error == 0 && (so->so_flags & SOF_DEFUNCT) &&
		    !(flags & SBL_IGNDEFUNCT)) {
			error = EBADF;
			SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] "
			    "(%d)\n", __func__, proc_selfpid(),
			    (uint64_t)VM_KERNEL_ADDRPERM(so),
			    SOCK_DOM(so), SOCK_TYPE(so), error));
		}

		if (error != 0)
			return (error);
	}
	sb->sb_flags |= SB_LOCK;
	return (0);
}

/*
 * Release lock on sockbuf sb
 */
void
sbunlock(struct sockbuf *sb, boolean_t keeplocked)
{
	void *lr_saved = __builtin_return_address(0);
	struct socket *so = sb->sb_so;
	thread_t tp = current_thread();

	/* so_usecount may be 0 if we get here from sofreelastref() */
	if (so == NULL) {
		panic("%s: null so, sb=%p sb_flags=0x%x lr=%p\n",
		    __func__, sb, sb->sb_flags, lr_saved);
		/* NOTREACHED */
	} else if (so->so_usecount < 0) {
		panic("%s: sb=%p sb_flags=0x%x sb_so=%p usecount=%d lr=%p "
		    "lrh= %s\n", __func__, sb, sb->sb_flags, so,
		    so->so_usecount, lr_saved, solockhistory_nr(so));
		/* NOTREACHED */
	}

	/*
	 * The content filter thread must hold the sockbuf lock
	 */
	if ((so->so_flags & SOF_CONTENT_FILTER) && sb->sb_cfil_thread == tp) {
		/*
		 * Don't panic if we are defunct because SB_LOCK has
		 * been cleared by sodefunct()
		 */
		if (!(so->so_flags & SOF_DEFUNCT) &&
		    !(sb->sb_flags & SB_LOCK) &&
		    !(so->so_state & SS_DEFUNCT) &&
		    !(so->so_flags1 & SOF1_DEFUNCTINPROG)) {
			panic("%s: SB_LOCK not held for %p\n",
			    __func__, sb);
		}
		/* Keep the sockbuf locked and proceed */
	} else {
		VERIFY((sb->sb_flags & SB_LOCK) ||
		    (so->so_state & SS_DEFUNCT) ||
		    (so->so_flags1 & SOF1_DEFUNCTINPROG));

		sb->sb_flags &= ~SB_LOCK;

		if (sb->sb_wantlock > 0) {
			/*
			 * We may get here from sorflush(), in which case "sb"
			 * may not point to the real socket buffer.  Use the
			 * actual socket buffer address from the socket instead.
			 */
			wakeup((sb->sb_flags & SB_RECV) ? &so->so_rcv.sb_flags :
			    &so->so_snd.sb_flags);
		}
	}

	if (!keeplocked) {	/* unlock on exit */
		lck_mtx_t *mutex_held;

		if (so->so_proto->pr_getlock != NULL)
			mutex_held = (*so->so_proto->pr_getlock)(so, 0);
		else
			mutex_held = so->so_proto->pr_domain->dom_mtx;

		lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

		VERIFY(so->so_usecount != 0);
		so->so_usecount--;
		so->unlock_lr[so->next_unlock_lr] = lr_saved;
		so->next_unlock_lr = (so->next_unlock_lr + 1) % SO_LCKDBG_MAX;
		lck_mtx_unlock(mutex_held);
	}
}

void
sorwakeup(struct socket *so)
{
	if (sb_notify(&so->so_rcv))
		sowakeup(so, &so->so_rcv);
}

void
sowwakeup(struct socket *so)
{
	if (sb_notify(&so->so_snd))
		sowakeup(so, &so->so_snd);
}

void
soevent(struct socket *so, long hint)
{
	if (so->so_flags & SOF_KNOTE)
		KNOTE(&so->so_klist, hint);

	soevupcall(so, hint);

	/*
	 * Don't post an event if this a subflow socket or
	 * the app has opted out of using cellular interface
	 */
	if ((hint & SO_FILT_HINT_IFDENIED) &&
	    !(so->so_flags & SOF_MP_SUBFLOW) &&
	    !(so->so_restrictions & SO_RESTRICT_DENY_CELLULAR) &&
	    !(so->so_restrictions & SO_RESTRICT_DENY_EXPENSIVE))
		soevent_ifdenied(so);
}

void
soevupcall(struct socket *so, u_int32_t hint)
{
	if (so->so_event != NULL) {
		caddr_t so_eventarg = so->so_eventarg;
		int locked = hint & SO_FILT_HINT_LOCKED;

		hint &= so->so_eventmask;
		if (hint != 0) {
			if (locked)
				socket_unlock(so, 0);

			so->so_event(so, so_eventarg, hint);

			if (locked)
				socket_lock(so, 0);
		}
	}
}

static void
soevent_ifdenied(struct socket *so)
{
	struct kev_netpolicy_ifdenied ev_ifdenied;

	bzero(&ev_ifdenied, sizeof (ev_ifdenied));
	/*
	 * The event consumer is interested about the effective {upid,pid,uuid}
	 * info which can be different than the those related to the process
	 * that recently performed a system call on the socket, i.e. when the
	 * socket is delegated.
	 */
	if (so->so_flags & SOF_DELEGATED) {
		ev_ifdenied.ev_data.eupid = so->e_upid;
		ev_ifdenied.ev_data.epid = so->e_pid;
		uuid_copy(ev_ifdenied.ev_data.euuid, so->e_uuid);
	} else {
		ev_ifdenied.ev_data.eupid = so->last_upid;
		ev_ifdenied.ev_data.epid = so->last_pid;
		uuid_copy(ev_ifdenied.ev_data.euuid, so->last_uuid);
	}

	if (++so->so_ifdenied_notifies > 1) {
		/*
		 * Allow for at most one kernel event to be generated per
		 * socket; so_ifdenied_notifies is reset upon changes in
		 * the UUID policy.  See comments in inp_update_policy.
		 */
		if (net_io_policy_log) {
			uuid_string_t buf;

			uuid_unparse(ev_ifdenied.ev_data.euuid, buf);
			log(LOG_DEBUG, "%s[%d]: so 0x%llx [%d,%d] epid %d "
			    "euuid %s%s has %d redundant events supressed\n",
			    __func__, so->last_pid,
			    (uint64_t)VM_KERNEL_ADDRPERM(so), SOCK_DOM(so),
			    SOCK_TYPE(so), ev_ifdenied.ev_data.epid, buf,
			    ((so->so_flags & SOF_DELEGATED) ?
			    " [delegated]" : ""), so->so_ifdenied_notifies);
		}
	} else {
		if (net_io_policy_log) {
			uuid_string_t buf;

			uuid_unparse(ev_ifdenied.ev_data.euuid, buf);
			log(LOG_DEBUG, "%s[%d]: so 0x%llx [%d,%d] epid %d "
			    "euuid %s%s event posted\n", __func__,
			    so->last_pid, (uint64_t)VM_KERNEL_ADDRPERM(so),
			    SOCK_DOM(so), SOCK_TYPE(so),
			    ev_ifdenied.ev_data.epid, buf,
			    ((so->so_flags & SOF_DELEGATED) ?
			    " [delegated]" : ""));
		}
		netpolicy_post_msg(KEV_NETPOLICY_IFDENIED, &ev_ifdenied.ev_data,
		    sizeof (ev_ifdenied));
	}
}

/*
 * Make a copy of a sockaddr in a malloced buffer of type M_SONAME.
 */
struct sockaddr *
dup_sockaddr(struct sockaddr *sa, int canwait)
{
	struct sockaddr *sa2;

	MALLOC(sa2, struct sockaddr *, sa->sa_len, M_SONAME,
	    canwait ? M_WAITOK : M_NOWAIT);
	if (sa2)
		bcopy(sa, sa2, sa->sa_len);
	return (sa2);
}

/*
 * Create an external-format (``xsocket'') structure using the information
 * in the kernel-format socket structure pointed to by so.  This is done
 * to reduce the spew of irrelevant information over this interface,
 * to isolate user code from changes in the kernel structure, and
 * potentially to provide information-hiding if we decide that
 * some of this information should be hidden from users.
 */
void
sotoxsocket(struct socket *so, struct xsocket *xso)
{
	xso->xso_len = sizeof (*xso);
	xso->xso_so = (_XSOCKET_PTR(struct socket *))VM_KERNEL_ADDRPERM(so);
	xso->so_type = so->so_type;
	xso->so_options = (short)(so->so_options & 0xffff);
	xso->so_linger = so->so_linger;
	xso->so_state = so->so_state;
	xso->so_pcb = (_XSOCKET_PTR(caddr_t))VM_KERNEL_ADDRPERM(so->so_pcb);
	if (so->so_proto) {
		xso->xso_protocol = SOCK_PROTO(so);
		xso->xso_family = SOCK_DOM(so);
	} else {
		xso->xso_protocol = xso->xso_family = 0;
	}
	xso->so_qlen = so->so_qlen;
	xso->so_incqlen = so->so_incqlen;
	xso->so_qlimit = so->so_qlimit;
	xso->so_timeo = so->so_timeo;
	xso->so_error = so->so_error;
	xso->so_pgid = so->so_pgid;
	xso->so_oobmark = so->so_oobmark;
	sbtoxsockbuf(&so->so_snd, &xso->so_snd);
	sbtoxsockbuf(&so->so_rcv, &xso->so_rcv);
	xso->so_uid = kauth_cred_getuid(so->so_cred);
}



void
sotoxsocket64(struct socket *so, struct xsocket64 *xso)
{
	xso->xso_len = sizeof (*xso);
	xso->xso_so = (u_int64_t)VM_KERNEL_ADDRPERM(so);
	xso->so_type = so->so_type;
	xso->so_options = (short)(so->so_options & 0xffff);
	xso->so_linger = so->so_linger;
	xso->so_state = so->so_state;
	xso->so_pcb = (u_int64_t)VM_KERNEL_ADDRPERM(so->so_pcb);
	if (so->so_proto) {
		xso->xso_protocol = SOCK_PROTO(so);
		xso->xso_family = SOCK_DOM(so);
	} else {
		xso->xso_protocol = xso->xso_family = 0;
	}
	xso->so_qlen = so->so_qlen;
	xso->so_incqlen = so->so_incqlen;
	xso->so_qlimit = so->so_qlimit;
	xso->so_timeo = so->so_timeo;
	xso->so_error = so->so_error;
	xso->so_pgid = so->so_pgid;
	xso->so_oobmark = so->so_oobmark;
	sbtoxsockbuf(&so->so_snd, &xso->so_snd);
	sbtoxsockbuf(&so->so_rcv, &xso->so_rcv);
	xso->so_uid = kauth_cred_getuid(so->so_cred);
}


/*
 * This does the same for sockbufs.  Note that the xsockbuf structure,
 * since it is always embedded in a socket, does not include a self
 * pointer nor a length.  We make this entry point public in case
 * some other mechanism needs it.
 */
void
sbtoxsockbuf(struct sockbuf *sb, struct xsockbuf *xsb)
{
	xsb->sb_cc = sb->sb_cc;
	xsb->sb_hiwat = sb->sb_hiwat;
	xsb->sb_mbcnt = sb->sb_mbcnt;
	xsb->sb_mbmax = sb->sb_mbmax;
	xsb->sb_lowat = sb->sb_lowat;
	xsb->sb_flags = sb->sb_flags;
	xsb->sb_timeo = (short)
	    (sb->sb_timeo.tv_sec * hz) + sb->sb_timeo.tv_usec / tick;
	if (xsb->sb_timeo == 0 && sb->sb_timeo.tv_usec != 0)
		xsb->sb_timeo = 1;
}

/*
 * Based on the policy set by an all knowing decison maker, throttle sockets
 * that either have been marked as belonging to "background" process.
 */
inline int
soisthrottled(struct socket *so)
{
	/*
	 * On non-embedded, we rely on implicit throttling by the
	 * application, as we're missing the system wide "decision maker"
	 */
	return (
		(so->so_traffic_mgt_flags & TRAFFIC_MGT_SO_BACKGROUND));
}

inline int
soisprivilegedtraffic(struct socket *so)
{
	return ((so->so_flags & SOF_PRIVILEGED_TRAFFIC_CLASS) ? 1 : 0);
}

inline int
soissrcbackground(struct socket *so)
{
	return ((so->so_traffic_mgt_flags & TRAFFIC_MGT_SO_BACKGROUND) ||
		IS_SO_TC_BACKGROUND(so->so_traffic_class));
}

inline int
soissrcrealtime(struct socket *so)
{
	return (so->so_traffic_class >= SO_TC_AV &&
	    so->so_traffic_class <= SO_TC_VO);
}

inline int
soissrcbesteffort(struct socket *so)
{
	return (so->so_traffic_class == SO_TC_BE ||
	    so->so_traffic_class == SO_TC_RD ||
	    so->so_traffic_class == SO_TC_OAM);
}

void
sonullevent(struct socket *so, void *arg, uint32_t hint)
{
#pragma unused(so, arg, hint)
}

/*
 * Here is the definition of some of the basic objects in the kern.ipc
 * branch of the MIB.
 */
SYSCTL_NODE(_kern, KERN_IPC, ipc,
	CTLFLAG_RW|CTLFLAG_LOCKED|CTLFLAG_ANYBODY, 0, "IPC");

/* Check that the maximum socket buffer size is within a range */

static int
sysctl_sb_max SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
	u_int32_t new_value;
	int changed = 0;
	int error = sysctl_io_number(req, sb_max, sizeof (u_int32_t),
	    &new_value, &changed);
	if (!error && changed) {
		if (new_value > LOW_SB_MAX && new_value <= high_sb_max) {
			sb_max = new_value;
		} else {
			error = ERANGE;
		}
	}
	return (error);
}

static int
sysctl_io_policy_throttled SYSCTL_HANDLER_ARGS
{
#pragma unused(arg1, arg2)
	int i, err;

	i = net_io_policy_throttled;

	err = sysctl_handle_int(oidp, &i, 0, req);
	if (err != 0 || req->newptr == USER_ADDR_NULL)
		return (err);

	if (i != net_io_policy_throttled)
		SOTHROTTLELOG(("throttle: network IO policy throttling is "
		    "now %s\n", i ? "ON" : "OFF"));

	net_io_policy_throttled = i;

	return (err);
}

SYSCTL_PROC(_kern_ipc, KIPC_MAXSOCKBUF, maxsockbuf,
	CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED,
	&sb_max, 0, &sysctl_sb_max, "IU", "Maximum socket buffer size");

SYSCTL_INT(_kern_ipc, KIPC_SOCKBUF_WASTE, sockbuf_waste_factor,
	CTLFLAG_RW | CTLFLAG_LOCKED, &sb_efficiency, 0, "");

SYSCTL_INT(_kern_ipc, KIPC_NMBCLUSTERS, nmbclusters,
	CTLFLAG_RD | CTLFLAG_LOCKED, &nmbclusters, 0, "");

SYSCTL_INT(_kern_ipc, OID_AUTO, njcl,
	CTLFLAG_RD | CTLFLAG_LOCKED, &njcl, 0, "");

SYSCTL_INT(_kern_ipc, OID_AUTO, njclbytes,
	CTLFLAG_RD | CTLFLAG_LOCKED, &njclbytes, 0, "");

SYSCTL_INT(_kern_ipc, KIPC_SOQLIMITCOMPAT, soqlimitcompat,
	CTLFLAG_RW | CTLFLAG_LOCKED, &soqlimitcompat, 1,
	"Enable socket queue limit compatibility");

SYSCTL_INT(_kern_ipc, OID_AUTO, soqlencomp, CTLFLAG_RW | CTLFLAG_LOCKED,
	&soqlencomp, 0, "Listen backlog represents only complete queue");

SYSCTL_NODE(_kern_ipc, OID_AUTO, io_policy, CTLFLAG_RW, 0, "network IO policy");

SYSCTL_PROC(_kern_ipc_io_policy, OID_AUTO, throttled,
	CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &net_io_policy_throttled, 0,
	sysctl_io_policy_throttled, "I", "");

SYSCTL_INT(_kern_ipc_io_policy, OID_AUTO, log, CTLFLAG_RW | CTLFLAG_LOCKED,
	&net_io_policy_log, 0, "");

#if CONFIG_PROC_UUID_POLICY
SYSCTL_INT(_kern_ipc_io_policy, OID_AUTO, uuid, CTLFLAG_RW | CTLFLAG_LOCKED,
	&net_io_policy_uuid, 0, "");
#endif /* CONFIG_PROC_UUID_POLICY */