xnu-3247.10.11.tar.gz

[apple/xnu.git] / bsd / kern / uipc_socket.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_socket.c       8.3 (Berkeley) 4/15/94
 */
/*
 * 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/filedesc.h>
#include <sys/proc.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/file_internal.h>
#include <sys/fcntl.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/kernel.h>
#include <sys/event.h>
#include <sys/poll.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/uio.h>
#include <sys/uio_internal.h>
#include <sys/ev.h>
#include <sys/kdebug.h>
#include <sys/un.h>
#include <sys/user.h>
#include <sys/priv.h>
#include <sys/kern_event.h>
#include <net/route.h>
#include <net/init.h>
#include <net/ntstat.h>
#include <net/content_filter.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet/flow_divert.h>
#include <kern/zalloc.h>
#include <kern/locks.h>
#include <machine/limits.h>
#include <libkern/OSAtomic.h>
#include <pexpert/pexpert.h>
#include <kern/assert.h>
#include <kern/task.h>
#include <sys/kpi_mbuf.h>
#include <sys/mcache.h>
#include <sys/unpcb.h>

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

#if MULTIPATH
#include <netinet/mp_pcb.h>
#include <netinet/mptcp_var.h>
#endif /* MULTIPATH */

#define ROUNDUP(a, b) (((a) + ((b) - 1)) & (~((b) - 1)))

#if DEBUG || DEVELOPMENT
#define DEBUG_KERNEL_ADDRPERM(_v) (_v)
#else
#define DEBUG_KERNEL_ADDRPERM(_v) VM_KERNEL_ADDRPERM(_v)
#endif

/* TODO: this should be in a header file somewhere */
extern char *proc_name_address(void *p);

static u_int32_t        so_cache_hw;    /* High water mark for socache */
static u_int32_t        so_cache_timeouts;      /* number of timeouts */
static u_int32_t        so_cache_max_freed;     /* max freed per timeout */
static u_int32_t        cached_sock_count = 0;
STAILQ_HEAD(, socket)   so_cache_head;
int     max_cached_sock_count = MAX_CACHED_SOCKETS;
static u_int32_t        so_cache_time;
static int              socketinit_done;
static struct zone      *so_cache_zone;

static lck_grp_t        *so_cache_mtx_grp;
static lck_attr_t       *so_cache_mtx_attr;
static lck_grp_attr_t   *so_cache_mtx_grp_attr;
static lck_mtx_t        *so_cache_mtx;

#include <machine/limits.h>

static void     filt_sordetach(struct knote *kn);
static int      filt_soread(struct knote *kn, long hint);
static void     filt_sowdetach(struct knote *kn);
static int      filt_sowrite(struct knote *kn, long hint);
static void     filt_sockdetach(struct knote *kn);
static int      filt_sockev(struct knote *kn, long hint);
static void     filt_socktouch(struct knote *kn, struct kevent_internal_s *kev,
    long type);

static int sooptcopyin_timeval(struct sockopt *, struct timeval *);
static int sooptcopyout_timeval(struct sockopt *, const struct timeval *);

static struct filterops soread_filtops = {
        .f_isfd = 1,
        .f_detach = filt_sordetach,
        .f_event = filt_soread,
};

static struct filterops sowrite_filtops = {
        .f_isfd = 1,
        .f_detach = filt_sowdetach,
        .f_event = filt_sowrite,
};

static struct filterops sock_filtops = {
        .f_isfd = 1,
        .f_detach = filt_sockdetach,
        .f_event = filt_sockev,
        .f_touch = filt_socktouch,
};

SYSCTL_DECL(_kern_ipc);

#define EVEN_MORE_LOCKING_DEBUG 0

int socket_debug = 0;
SYSCTL_INT(_kern_ipc, OID_AUTO, socket_debug,
        CTLFLAG_RW | CTLFLAG_LOCKED, &socket_debug, 0, "");

static int socket_zone = M_SOCKET;
so_gen_t        so_gencnt;      /* generation count for sockets */

MALLOC_DEFINE(M_SONAME, "soname", "socket name");
MALLOC_DEFINE(M_PCB, "pcb", "protocol control block");

#define DBG_LAYER_IN_BEG        NETDBG_CODE(DBG_NETSOCK, 0)
#define DBG_LAYER_IN_END        NETDBG_CODE(DBG_NETSOCK, 2)
#define DBG_LAYER_OUT_BEG       NETDBG_CODE(DBG_NETSOCK, 1)
#define DBG_LAYER_OUT_END       NETDBG_CODE(DBG_NETSOCK, 3)
#define DBG_FNC_SOSEND          NETDBG_CODE(DBG_NETSOCK, (4 << 8) | 1)
#define DBG_FNC_SOSEND_LIST     NETDBG_CODE(DBG_NETSOCK, (4 << 8) | 3)
#define DBG_FNC_SORECEIVE       NETDBG_CODE(DBG_NETSOCK, (8 << 8))
#define DBG_FNC_SORECEIVE_LIST  NETDBG_CODE(DBG_NETSOCK, (8 << 8) | 3)
#define DBG_FNC_SOSHUTDOWN      NETDBG_CODE(DBG_NETSOCK, (9 << 8))

#define MAX_SOOPTGETM_SIZE      (128 * MCLBYTES)

int somaxconn = SOMAXCONN;
SYSCTL_INT(_kern_ipc, KIPC_SOMAXCONN, somaxconn,
        CTLFLAG_RW | CTLFLAG_LOCKED, &somaxconn, 0, "");

/* Should we get a maximum also ??? */
static int sosendmaxchain = 65536;
static int sosendminchain = 16384;
static int sorecvmincopy  = 16384;
SYSCTL_INT(_kern_ipc, OID_AUTO, sosendminchain,
        CTLFLAG_RW | CTLFLAG_LOCKED, &sosendminchain, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, sorecvmincopy,
        CTLFLAG_RW | CTLFLAG_LOCKED, &sorecvmincopy, 0, "");

/*
 * Set to enable jumbo clusters (if available) for large writes when
 * the socket is marked with SOF_MULTIPAGES; see below.
 */
int sosendjcl = 1;
SYSCTL_INT(_kern_ipc, OID_AUTO, sosendjcl,
        CTLFLAG_RW | CTLFLAG_LOCKED, &sosendjcl, 0, "");

/*
 * Set this to ignore SOF_MULTIPAGES and use jumbo clusters for large
 * writes on the socket for all protocols on any network interfaces,
 * depending upon sosendjcl above.  Be extra careful when setting this
 * to 1, because sending down packets that cross physical pages down to
 * broken drivers (those that falsely assume that the physical pages
 * are contiguous) might lead to system panics or silent data corruption.
 * When set to 0, the system will respect SOF_MULTIPAGES, which is set
 * only for TCP sockets whose outgoing interface is IFNET_MULTIPAGES
 * capable.  Set this to 1 only for testing/debugging purposes.
 */
int sosendjcl_ignore_capab = 0;
SYSCTL_INT(_kern_ipc, OID_AUTO, sosendjcl_ignore_capab,
        CTLFLAG_RW | CTLFLAG_LOCKED, &sosendjcl_ignore_capab, 0, "");

/*
 * Set this to ignore SOF1_IF_2KCL and use big clusters for large
 * writes on the socket for all protocols on any network interfaces.
 * Be extra careful when setting this to 1, because sending down packets with
 * clusters larger that 2 KB might lead to system panics or data corruption.
 * When set to 0, the system will respect SOF1_IF_2KCL, which is set
 * on the outgoing interface
 * Set this to 1  for testing/debugging purposes only.
 */
int sosendbigcl_ignore_capab = 0;
SYSCTL_INT(_kern_ipc, OID_AUTO, sosendbigcl_ignore_capab,
        CTLFLAG_RW | CTLFLAG_LOCKED, &sosendbigcl_ignore_capab, 0, "");

int sodefunctlog = 0;
SYSCTL_INT(_kern_ipc, OID_AUTO, sodefunctlog, CTLFLAG_RW | CTLFLAG_LOCKED,
        &sodefunctlog, 0, "");

int sothrottlelog = 0;
SYSCTL_INT(_kern_ipc, OID_AUTO, sothrottlelog, CTLFLAG_RW | CTLFLAG_LOCKED,
        &sothrottlelog, 0, "");

int sorestrictrecv = 1;
SYSCTL_INT(_kern_ipc, OID_AUTO, sorestrictrecv, CTLFLAG_RW | CTLFLAG_LOCKED,
        &sorestrictrecv, 0, "Enable inbound interface restrictions");

int sorestrictsend = 1;
SYSCTL_INT(_kern_ipc, OID_AUTO, sorestrictsend, CTLFLAG_RW | CTLFLAG_LOCKED,
        &sorestrictsend, 0, "Enable outbound interface restrictions");

int soreserveheadroom = 1;
SYSCTL_INT(_kern_ipc, OID_AUTO, soreserveheadroom, CTLFLAG_RW | CTLFLAG_LOCKED,
        &soreserveheadroom, 0, "To allocate contiguous datagram buffers");

extern struct inpcbinfo tcbinfo;

/* TODO: these should be in header file */
extern int get_inpcb_str_size(void);
extern int get_tcp_str_size(void);

static unsigned int sl_zone_size;               /* size of sockaddr_list */
static struct zone *sl_zone;                    /* zone for sockaddr_list */

static unsigned int se_zone_size;               /* size of sockaddr_entry */
static struct zone *se_zone;                    /* zone for sockaddr_entry */

vm_size_t       so_cache_zone_element_size;

static int sodelayed_copy(struct socket *, struct uio *, struct mbuf **,
    user_ssize_t *);
static void cached_sock_alloc(struct socket **, int);
static void cached_sock_free(struct socket *);

/*
 * Maximum of extended background idle sockets per process
 * Set to zero to disable further setting of the option
 */

#define SO_IDLE_BK_IDLE_MAX_PER_PROC    1
#define SO_IDLE_BK_IDLE_TIME            600
#define SO_IDLE_BK_IDLE_RCV_HIWAT       131072

struct soextbkidlestat soextbkidlestat;

SYSCTL_UINT(_kern_ipc, OID_AUTO, maxextbkidleperproc,
        CTLFLAG_RW | CTLFLAG_LOCKED, &soextbkidlestat.so_xbkidle_maxperproc, 0,
        "Maximum of extended background idle sockets per process");

SYSCTL_UINT(_kern_ipc, OID_AUTO, extbkidletime, CTLFLAG_RW | CTLFLAG_LOCKED,
        &soextbkidlestat.so_xbkidle_time, 0,
        "Time in seconds to keep extended background idle sockets");

SYSCTL_UINT(_kern_ipc, OID_AUTO, extbkidlercvhiwat, CTLFLAG_RW | CTLFLAG_LOCKED,
        &soextbkidlestat.so_xbkidle_rcvhiwat, 0,
        "High water mark for extended background idle sockets");

SYSCTL_STRUCT(_kern_ipc, OID_AUTO, extbkidlestat, CTLFLAG_RD | CTLFLAG_LOCKED,
        &soextbkidlestat, soextbkidlestat, "");

int so_set_extended_bk_idle(struct socket *, int);

/*
 * SOTCDB_NO_DSCP is set by default, to prevent the networking stack from
 * setting the DSCP code on the packet based on the service class; see
 * <rdar://problem/11277343> for details.
 */
__private_extern__ u_int32_t sotcdb = SOTCDB_NO_DSCP;
SYSCTL_INT(_kern_ipc, OID_AUTO, sotcdb, CTLFLAG_RW | CTLFLAG_LOCKED,
        &sotcdb, 0, "");

void
socketinit(void)
{
        _CASSERT(sizeof(so_gencnt) == sizeof(uint64_t));
        VERIFY(IS_P2ALIGNED(&so_gencnt, sizeof(uint32_t)));

#ifdef __LP64__
        _CASSERT(sizeof(struct sa_endpoints) == sizeof(struct user64_sa_endpoints));
        _CASSERT(offsetof(struct sa_endpoints, sae_srcif) == offsetof(struct user64_sa_endpoints, sae_srcif));
        _CASSERT(offsetof(struct sa_endpoints, sae_srcaddr) == offsetof(struct user64_sa_endpoints, sae_srcaddr));
        _CASSERT(offsetof(struct sa_endpoints, sae_srcaddrlen) == offsetof(struct user64_sa_endpoints, sae_srcaddrlen));
        _CASSERT(offsetof(struct sa_endpoints, sae_dstaddr) == offsetof(struct user64_sa_endpoints, sae_dstaddr));
        _CASSERT(offsetof(struct sa_endpoints, sae_dstaddrlen) == offsetof(struct user64_sa_endpoints, sae_dstaddrlen));
#else
        _CASSERT(sizeof(struct sa_endpoints) == sizeof(struct user32_sa_endpoints));
        _CASSERT(offsetof(struct sa_endpoints, sae_srcif) == offsetof(struct user32_sa_endpoints, sae_srcif));
        _CASSERT(offsetof(struct sa_endpoints, sae_srcaddr) == offsetof(struct user32_sa_endpoints, sae_srcaddr));
        _CASSERT(offsetof(struct sa_endpoints, sae_srcaddrlen) == offsetof(struct user32_sa_endpoints, sae_srcaddrlen));
        _CASSERT(offsetof(struct sa_endpoints, sae_dstaddr) == offsetof(struct user32_sa_endpoints, sae_dstaddr));
        _CASSERT(offsetof(struct sa_endpoints, sae_dstaddrlen) == offsetof(struct user32_sa_endpoints, sae_dstaddrlen));
#endif

        if (socketinit_done) {
                printf("socketinit: already called...\n");
                return;
        }
        socketinit_done = 1;

        PE_parse_boot_argn("socket_debug", &socket_debug,
            sizeof (socket_debug));

        /*
         * allocate lock group attribute and group for socket cache mutex
         */
        so_cache_mtx_grp_attr = lck_grp_attr_alloc_init();
        so_cache_mtx_grp = lck_grp_alloc_init("so_cache",
            so_cache_mtx_grp_attr);

        /*
         * allocate the lock attribute for socket cache mutex
         */
        so_cache_mtx_attr = lck_attr_alloc_init();

        /* cached sockets mutex */
        so_cache_mtx = lck_mtx_alloc_init(so_cache_mtx_grp, so_cache_mtx_attr);
        if (so_cache_mtx == NULL) {
                panic("%s: unable to allocate so_cache_mtx\n", __func__);
                /* NOTREACHED */
        }
        STAILQ_INIT(&so_cache_head);

        so_cache_zone_element_size = (vm_size_t)(sizeof (struct socket) + 4
            + get_inpcb_str_size() + 4 + get_tcp_str_size());

        so_cache_zone = zinit(so_cache_zone_element_size,
            (120000 * so_cache_zone_element_size), 8192, "socache zone");
        zone_change(so_cache_zone, Z_CALLERACCT, FALSE);
        zone_change(so_cache_zone, Z_NOENCRYPT, TRUE);

        sl_zone_size = sizeof (struct sockaddr_list);
        if ((sl_zone = zinit(sl_zone_size, 1024 * sl_zone_size, 1024,
            "sockaddr_list")) == NULL) {
                panic("%s: unable to allocate sockaddr_list zone\n", __func__);
                /* NOTREACHED */
        }
        zone_change(sl_zone, Z_CALLERACCT, FALSE);
        zone_change(sl_zone, Z_EXPAND, TRUE);

        se_zone_size = sizeof (struct sockaddr_entry);
        if ((se_zone = zinit(se_zone_size, 1024 * se_zone_size, 1024,
            "sockaddr_entry")) == NULL) {
                panic("%s: unable to allocate sockaddr_entry zone\n", __func__);
                /* NOTREACHED */
        }
        zone_change(se_zone, Z_CALLERACCT, FALSE);
        zone_change(se_zone, Z_EXPAND, TRUE);

        bzero(&soextbkidlestat, sizeof(struct soextbkidlestat));
        soextbkidlestat.so_xbkidle_maxperproc = SO_IDLE_BK_IDLE_MAX_PER_PROC;
        soextbkidlestat.so_xbkidle_time = SO_IDLE_BK_IDLE_TIME;
        soextbkidlestat.so_xbkidle_rcvhiwat = SO_IDLE_BK_IDLE_RCV_HIWAT;

        in_pcbinit();
        sflt_init();
        socket_tclass_init();
#if MULTIPATH
        mp_pcbinit();
#endif /* MULTIPATH */
}

static void
cached_sock_alloc(struct socket **so, int waitok)
{
        caddr_t temp;
        uintptr_t offset;

        lck_mtx_lock(so_cache_mtx);

        if (!STAILQ_EMPTY(&so_cache_head)) {
                VERIFY(cached_sock_count > 0);

                *so = STAILQ_FIRST(&so_cache_head);
                STAILQ_REMOVE_HEAD(&so_cache_head, so_cache_ent);
                STAILQ_NEXT((*so), so_cache_ent) = NULL;

                cached_sock_count--;
                lck_mtx_unlock(so_cache_mtx);

                temp = (*so)->so_saved_pcb;
                bzero((caddr_t)*so, sizeof (struct socket));

                (*so)->so_saved_pcb = temp;
        } else {

                lck_mtx_unlock(so_cache_mtx);

                if (waitok)
                        *so = (struct socket *)zalloc(so_cache_zone);
                else
                        *so = (struct socket *)zalloc_noblock(so_cache_zone);

                if (*so == NULL)
                        return;

                bzero((caddr_t)*so, sizeof (struct socket));

                /*
                 * Define offsets for extra structures into our
                 * single block of memory. Align extra structures
                 * on longword boundaries.
                 */

                offset = (uintptr_t)*so;
                offset += sizeof (struct socket);

                offset = ALIGN(offset);

                (*so)->so_saved_pcb = (caddr_t)offset;
                offset += get_inpcb_str_size();

                offset = ALIGN(offset);

                ((struct inpcb *)(void *)(*so)->so_saved_pcb)->inp_saved_ppcb =
                    (caddr_t)offset;
        }

        OSBitOrAtomic(SOF1_CACHED_IN_SOCK_LAYER, &(*so)->so_flags1);
}

static void
cached_sock_free(struct socket *so)
{

        lck_mtx_lock(so_cache_mtx);

        so_cache_time = net_uptime();
        if (++cached_sock_count > max_cached_sock_count) {
                --cached_sock_count;
                lck_mtx_unlock(so_cache_mtx);
                zfree(so_cache_zone, so);
        } else {
                if (so_cache_hw < cached_sock_count)
                        so_cache_hw = cached_sock_count;

                STAILQ_INSERT_TAIL(&so_cache_head, so, so_cache_ent);

                so->cache_timestamp = so_cache_time;
                lck_mtx_unlock(so_cache_mtx);
        }
}

void
so_update_last_owner_locked(struct socket *so, proc_t self)
{
        if (so->last_pid != 0) {
                /*
                 * last_pid and last_upid should remain zero for sockets
                 * created using sock_socket. The check above achieves that
                 */
                if (self == PROC_NULL)
                        self = current_proc();

                if (so->last_upid != proc_uniqueid(self) ||
                    so->last_pid != proc_pid(self)) {
                        so->last_upid = proc_uniqueid(self);
                        so->last_pid = proc_pid(self);
                        proc_getexecutableuuid(self, so->last_uuid,
                            sizeof (so->last_uuid));
                }
                proc_pidoriginatoruuid(so->so_vuuid, sizeof(so->so_vuuid));
        }
}

void
so_update_policy(struct socket *so)
{
        if (SOCK_DOM(so) == PF_INET || SOCK_DOM(so) == PF_INET6)
                (void) inp_update_policy(sotoinpcb(so));
}

#if NECP
static void
so_update_necp_policy(struct socket *so, struct sockaddr *override_local_addr,
    struct sockaddr *override_remote_addr)
{
        if (SOCK_DOM(so) == PF_INET || SOCK_DOM(so) == PF_INET6)
                inp_update_necp_policy(sotoinpcb(so), override_local_addr,
                    override_remote_addr, 0);
}
#endif /* NECP */

boolean_t
so_cache_timer(void)
{
        struct socket   *p;
        int             n_freed = 0;
        boolean_t rc = FALSE;

        lck_mtx_lock(so_cache_mtx);
        so_cache_timeouts++;
        so_cache_time = net_uptime();

        while (!STAILQ_EMPTY(&so_cache_head)) {
                VERIFY(cached_sock_count > 0);
                p = STAILQ_FIRST(&so_cache_head);
                if ((so_cache_time - p->cache_timestamp) <
                        SO_CACHE_TIME_LIMIT)
                        break;

                STAILQ_REMOVE_HEAD(&so_cache_head, so_cache_ent);
                --cached_sock_count;

                zfree(so_cache_zone, p);

                if (++n_freed >= SO_CACHE_MAX_FREE_BATCH) {
                        so_cache_max_freed++;
                        break;
                }
        }

        /* Schedule again if there is more to cleanup */
        if (!STAILQ_EMPTY(&so_cache_head))
                rc = TRUE;

        lck_mtx_unlock(so_cache_mtx);
        return (rc);
}

/*
 * Get a socket structure from our zone, and initialize it.
 * We don't implement `waitok' yet (see comments in uipc_domain.c).
 * Note that it would probably be better to allocate socket
 * and PCB at the same time, but I'm not convinced that all
 * the protocols can be easily modified to do this.
 */
struct socket *
soalloc(int waitok, int dom, int type)
{
        struct socket *so;

        if ((dom == PF_INET) && (type == SOCK_STREAM)) {
                cached_sock_alloc(&so, waitok);
        } else {
                MALLOC_ZONE(so, struct socket *, sizeof (*so), socket_zone,
                    M_WAITOK);
                if (so != NULL)
                        bzero(so, sizeof (*so));
        }
        if (so != NULL) {
                so->so_gencnt = OSIncrementAtomic64((SInt64 *)&so_gencnt);
                so->so_zone = socket_zone;
#if CONFIG_MACF_SOCKET
                /* Convert waitok to  M_WAITOK/M_NOWAIT for MAC Framework. */
                if (mac_socket_label_init(so, !waitok) != 0) {
                        sodealloc(so);
                        return (NULL);
                }
#endif /* MAC_SOCKET */
        }

        return (so);
}

int
socreate_internal(int dom, struct socket **aso, int type, int proto,
    struct proc *p, uint32_t flags, struct proc *ep)
{
        struct protosw *prp;
        struct socket *so;
        int error = 0;

#if TCPDEBUG
        extern int tcpconsdebug;
#endif

        VERIFY(aso != NULL);
        *aso = NULL;

        if (proto != 0)
                prp = pffindproto(dom, proto, type);
        else
                prp = pffindtype(dom, type);

        if (prp == NULL || prp->pr_usrreqs->pru_attach == NULL) {
                if (pffinddomain(dom) == NULL)
                        return (EAFNOSUPPORT);
                if (proto != 0) {
                        if (pffindprotonotype(dom, proto) != NULL)
                                return (EPROTOTYPE);
                }
                return (EPROTONOSUPPORT);
        }
        if (prp->pr_type != type)
                return (EPROTOTYPE);
        so = soalloc(1, dom, type);
        if (so == NULL)
                return (ENOBUFS);

        if (flags & SOCF_ASYNC)
                so->so_state |= SS_NBIO;
#if MULTIPATH
        if (flags & SOCF_MP_SUBFLOW) {
                /*
                 * A multipath subflow socket is used internally in the kernel,
                 * therefore it does not have a file desciptor associated by
                 * default.
                 */
                so->so_state |= SS_NOFDREF;
                so->so_flags |= SOF_MP_SUBFLOW;
        }
#endif /* MULTIPATH */

        TAILQ_INIT(&so->so_incomp);
        TAILQ_INIT(&so->so_comp);
        so->so_type = type;
        so->last_upid = proc_uniqueid(p);
        so->last_pid = proc_pid(p);
        proc_getexecutableuuid(p, so->last_uuid, sizeof (so->last_uuid));
        proc_pidoriginatoruuid(so->so_vuuid, sizeof(so->so_vuuid));

        if (ep != PROC_NULL && ep != p) {
                so->e_upid = proc_uniqueid(ep);
                so->e_pid = proc_pid(ep);
                proc_getexecutableuuid(ep, so->e_uuid, sizeof (so->e_uuid));
                so->so_flags |= SOF_DELEGATED;
        }

        so->so_cred = kauth_cred_proc_ref(p);
        if (!suser(kauth_cred_get(), NULL))
                so->so_state |= SS_PRIV;

        so->so_proto = prp;
        so->so_rcv.sb_flags |= SB_RECV;
        so->so_rcv.sb_so = so->so_snd.sb_so = so;
        so->next_lock_lr = 0;
        so->next_unlock_lr = 0;

#if CONFIG_MACF_SOCKET
        mac_socket_label_associate(kauth_cred_get(), so);
#endif /* MAC_SOCKET */

        /*
         * Attachment will create the per pcb lock if necessary and
         * increase refcount for creation, make sure it's done before
         * socket is inserted in lists.
         */
        so->so_usecount++;

        error = (*prp->pr_usrreqs->pru_attach)(so, proto, p);
        if (error != 0) {
                /*
                 * Warning:
                 * If so_pcb is not zero, the socket will be leaked,
                 * so protocol attachment handler must be coded carefuly
                 */
                so->so_state |= SS_NOFDREF;
                so->so_usecount--;
                sofreelastref(so, 1);   /* will deallocate the socket */
                return (error);
        }

        atomic_add_32(&prp->pr_domain->dom_refs, 1);
        TAILQ_INIT(&so->so_evlist);

        /* Attach socket filters for this protocol */
        sflt_initsock(so);
#if TCPDEBUG
        if (tcpconsdebug == 2)
                so->so_options |= SO_DEBUG;
#endif
        so_set_default_traffic_class(so);

        /*
         * If this thread or task is marked to create backgrounded sockets,
         * mark the socket as background.
         */
        if (proc_get_effective_thread_policy(current_thread(),
            TASK_POLICY_NEW_SOCKETS_BG)) {
                socket_set_traffic_mgt_flags(so, TRAFFIC_MGT_SO_BACKGROUND);
                so->so_background_thread = current_thread();
        }

        switch (dom) {
        /*
         * Don't mark Unix domain, system or multipath sockets as
         * eligible for defunct by default.
         */
        case PF_LOCAL:
        case PF_SYSTEM:
        case PF_MULTIPATH:
                so->so_flags |= SOF_NODEFUNCT;
                break;
        default:
                break;
        }

        /*
         * Entitlements can't be checked at socket creation time except if the
         * application requested a feature guarded by a privilege (c.f., socket
         * delegation).
         * The priv(9) and the Sandboxing APIs are designed with the idea that
         * a privilege check should only be triggered by a userland request.
         * A privilege check at socket creation time is time consuming and
         * could trigger many authorisation error messages from the security
         * APIs.
         */

        *aso = so;

        return (0);
}

/*
 * Returns:     0                       Success
 *              EAFNOSUPPORT
 *              EPROTOTYPE
 *              EPROTONOSUPPORT
 *              ENOBUFS
 *      <pru_attach>:ENOBUFS[AF_UNIX]
 *      <pru_attach>:ENOBUFS[TCP]
 *      <pru_attach>:ENOMEM[TCP]
 *      <pru_attach>:???                [other protocol families, IPSEC]
 */
int
socreate(int dom, struct socket **aso, int type, int proto)
{
        return (socreate_internal(dom, aso, type, proto, current_proc(), 0,
            PROC_NULL));
}

int
socreate_delegate(int dom, struct socket **aso, int type, int proto, pid_t epid)
{
        int error = 0;
        struct proc *ep = PROC_NULL;

        if ((proc_selfpid() != epid) && ((ep = proc_find(epid)) == PROC_NULL)) {
                error = ESRCH;
                goto done;
        }

        error = socreate_internal(dom, aso, type, proto, current_proc(), 0, ep);

        /*
         * It might not be wise to hold the proc reference when calling
         * socreate_internal since it calls soalloc with M_WAITOK
         */
done:
        if (ep != PROC_NULL)
                proc_rele(ep);

        return (error);
}

/*
 * Returns:     0                       Success
 *      <pru_bind>:EINVAL               Invalid argument [COMMON_START]
 *      <pru_bind>:EAFNOSUPPORT         Address family not supported
 *      <pru_bind>:EADDRNOTAVAIL        Address not available.
 *      <pru_bind>:EINVAL               Invalid argument
 *      <pru_bind>:EAFNOSUPPORT         Address family not supported [notdef]
 *      <pru_bind>:EACCES               Permission denied
 *      <pru_bind>:EADDRINUSE           Address in use
 *      <pru_bind>:EAGAIN               Resource unavailable, try again
 *      <pru_bind>:EPERM                Operation not permitted
 *      <pru_bind>:???
 *      <sf_bind>:???
 *
 * Notes:       It's not possible to fully enumerate the return codes above,
 *              since socket filter authors and protocol family authors may
 *              not choose to limit their error returns to those listed, even
 *              though this may result in some software operating incorrectly.
 *
 *              The error codes which are enumerated above are those known to
 *              be returned by the tcp_usr_bind function supplied.
 */
int
sobindlock(struct socket *so, struct sockaddr *nam, int dolock)
{
        struct proc *p = current_proc();
        int error = 0;

        if (dolock)
                socket_lock(so, 1);
        VERIFY(so->so_usecount > 1);

        so_update_last_owner_locked(so, p);
        so_update_policy(so);

#if NECP
        so_update_necp_policy(so, nam, NULL);
#endif /* NECP */

        /*
         * If this is a bind request on a socket that has been marked
         * as inactive, reject it now before we go any further.
         */
        if (so->so_flags & SOF_DEFUNCT) {
                error = EINVAL;
                SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] (%d)\n",
                    __func__, proc_pid(p), (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so), error));
                goto out;
        }

        /* Socket filter */
        error = sflt_bind(so, nam);

        if (error == 0)
                error = (*so->so_proto->pr_usrreqs->pru_bind)(so, nam, p);
out:
        if (dolock)
                socket_unlock(so, 1);

        if (error == EJUSTRETURN)
                error = 0;

        return (error);
}

void
sodealloc(struct socket *so)
{
        kauth_cred_unref(&so->so_cred);

        /* Remove any filters */
        sflt_termsock(so);

#if CONTENT_FILTER
        cfil_sock_detach(so);
#endif /* CONTENT_FILTER */

        /* Delete the state allocated for msg queues on a socket */
        if (so->so_flags & SOF_ENABLE_MSGS) {
                FREE(so->so_msg_state, M_TEMP);
                so->so_msg_state = NULL;
        }
        VERIFY(so->so_msg_state == NULL);

        so->so_gencnt = OSIncrementAtomic64((SInt64 *)&so_gencnt);

#if CONFIG_MACF_SOCKET
        mac_socket_label_destroy(so);
#endif /* MAC_SOCKET */

        if (so->so_flags1 & SOF1_CACHED_IN_SOCK_LAYER) {
                cached_sock_free(so);
        } else {
                FREE_ZONE(so, sizeof (*so), so->so_zone);
        }
}

/*
 * Returns:     0                       Success
 *              EINVAL
 *              EOPNOTSUPP
 *      <pru_listen>:EINVAL[AF_UNIX]
 *      <pru_listen>:EINVAL[TCP]
 *      <pru_listen>:EADDRNOTAVAIL[TCP] Address not available.
 *      <pru_listen>:EINVAL[TCP]        Invalid argument
 *      <pru_listen>:EAFNOSUPPORT[TCP]  Address family not supported [notdef]
 *      <pru_listen>:EACCES[TCP]        Permission denied
 *      <pru_listen>:EADDRINUSE[TCP]    Address in use
 *      <pru_listen>:EAGAIN[TCP]        Resource unavailable, try again
 *      <pru_listen>:EPERM[TCP]         Operation not permitted
 *      <sf_listen>:???
 *
 * Notes:       Other <pru_listen> returns depend on the protocol family; all
 *              <sf_listen> returns depend on what the filter author causes
 *              their filter to return.
 */
int
solisten(struct socket *so, int backlog)
{
        struct proc *p = current_proc();
        int error = 0;

        socket_lock(so, 1);

        so_update_last_owner_locked(so, p);
        so_update_policy(so);

#if NECP
        so_update_necp_policy(so, NULL, NULL);
#endif /* NECP */

        if (so->so_proto == NULL) {
                error = EINVAL;
                goto out;
        }
        if ((so->so_proto->pr_flags & PR_CONNREQUIRED) == 0) {
                error = EOPNOTSUPP;
                goto out;
        }

        /*
         * If the listen request is made on a socket that is not fully
         * disconnected, or on a socket that has been marked as inactive,
         * reject the request now.
         */
        if ((so->so_state &
            (SS_ISCONNECTED|SS_ISCONNECTING|SS_ISDISCONNECTING)) ||
            (so->so_flags & SOF_DEFUNCT)) {
                error = EINVAL;
                if (so->so_flags & SOF_DEFUNCT) {
                        SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] "
                            "(%d)\n", __func__, proc_pid(p),
                            (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                            SOCK_DOM(so), SOCK_TYPE(so), error));
                }
                goto out;
        }

        if ((so->so_restrictions & SO_RESTRICT_DENY_IN) != 0) {
                error = EPERM;
                goto out;
        }

        error = sflt_listen(so);
        if (error == 0)
                error = (*so->so_proto->pr_usrreqs->pru_listen)(so, p);

        if (error) {
                if (error == EJUSTRETURN)
                        error = 0;
                goto out;
        }

        if (TAILQ_EMPTY(&so->so_comp))
                so->so_options |= SO_ACCEPTCONN;
        /*
         * POSIX: The implementation may have an upper limit on the length of
         * the listen queue-either global or per accepting socket. If backlog
         * exceeds this limit, the length of the listen queue is set to the
         * limit.
         *
         * If listen() is called with a backlog argument value that is less
         * than 0, the function behaves as if it had been called with a backlog
         * argument value of 0.
         *
         * A backlog argument of 0 may allow the socket to accept connections,
         * in which case the length of the listen queue may be set to an
         * implementation-defined minimum value.
         */
        if (backlog <= 0 || backlog > somaxconn)
                backlog = somaxconn;

        so->so_qlimit = backlog;
out:
        socket_unlock(so, 1);
        return (error);
}

void
sofreelastref(struct socket *so, int dealloc)
{
        struct socket *head = so->so_head;

        /* Assume socket is locked */

        if (!(so->so_flags & SOF_PCBCLEARING) || !(so->so_state & SS_NOFDREF)) {
                selthreadclear(&so->so_snd.sb_sel);
                selthreadclear(&so->so_rcv.sb_sel);
                so->so_rcv.sb_flags &= ~(SB_SEL|SB_UPCALL);
                so->so_snd.sb_flags &= ~(SB_SEL|SB_UPCALL);
                so->so_event = sonullevent;
                return;
        }
        if (head != NULL) {
                socket_lock(head, 1);
                if (so->so_state & SS_INCOMP) {
                        TAILQ_REMOVE(&head->so_incomp, so, so_list);
                        head->so_incqlen--;
                } else if (so->so_state & SS_COMP) {
                        /*
                         * We must not decommission a socket that's
                         * on the accept(2) queue.  If we do, then
                         * accept(2) may hang after select(2) indicated
                         * that the listening socket was ready.
                         */
                        selthreadclear(&so->so_snd.sb_sel);
                        selthreadclear(&so->so_rcv.sb_sel);
                        so->so_rcv.sb_flags &= ~(SB_SEL|SB_UPCALL);
                        so->so_snd.sb_flags &= ~(SB_SEL|SB_UPCALL);
                        so->so_event = sonullevent;
                        socket_unlock(head, 1);
                        return;
                } else {
                        panic("sofree: not queued");
                }
                head->so_qlen--;
                so->so_state &= ~SS_INCOMP;
                so->so_head = NULL;
                socket_unlock(head, 1);
        }
        sowflush(so);
        sorflush(so);

#if FLOW_DIVERT
        if (so->so_flags & SOF_FLOW_DIVERT) {
                flow_divert_detach(so);
        }
#endif  /* FLOW_DIVERT */

        /* 3932268: disable upcall */
        so->so_rcv.sb_flags &= ~SB_UPCALL;
        so->so_snd.sb_flags &= ~SB_UPCALL;
        so->so_event = sonullevent;

        if (dealloc)
                sodealloc(so);
}

void
soclose_wait_locked(struct socket *so)
{
        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);

        /*
         * Double check here and return if there's no outstanding upcall;
         * otherwise proceed further only if SOF_UPCALLCLOSEWAIT is set.
         */
        if (!so->so_upcallusecount || !(so->so_flags & SOF_UPCALLCLOSEWAIT))
                return;
        so->so_rcv.sb_flags &= ~SB_UPCALL;
        so->so_snd.sb_flags &= ~SB_UPCALL;
        so->so_flags |= SOF_CLOSEWAIT;
        (void) msleep((caddr_t)&so->so_upcallusecount, mutex_held, (PZERO - 1),
            "soclose_wait_locked", NULL);
        lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);
        so->so_flags &= ~SOF_CLOSEWAIT;
}

/*
 * Close a socket on last file table reference removal.
 * Initiate disconnect if connected.
 * Free socket when disconnect complete.
 */
int
soclose_locked(struct socket *so)
{
        int error = 0;
        lck_mtx_t *mutex_held;
        struct timespec ts;

        if (so->so_usecount == 0) {
                panic("soclose: so=%p refcount=0\n", so);
                /* NOTREACHED */
        }

        sflt_notify(so, sock_evt_closing, NULL);

        if (so->so_upcallusecount)
                soclose_wait_locked(so);

#if CONTENT_FILTER
        /*
         * We have to wait until the content filters are done
         */
        if ((so->so_flags & SOF_CONTENT_FILTER) != 0) {
                cfil_sock_close_wait(so);
                cfil_sock_is_closed(so);
                cfil_sock_detach(so);
        }
#endif /* CONTENT_FILTER */

        if (so->so_flags1 & SOF1_EXTEND_BK_IDLE_INPROG) {
                soresume(current_proc(), so, 1);
                so->so_flags1 &= ~SOF1_EXTEND_BK_IDLE_WANTED;
        }

        if ((so->so_options & SO_ACCEPTCONN)) {
                struct socket *sp, *sonext;
                int socklock = 0;

                /*
                 * We do not want new connection to be added
                 * to the connection queues
                 */
                so->so_options &= ~SO_ACCEPTCONN;

                for (sp = TAILQ_FIRST(&so->so_incomp);
                    sp != NULL; sp = sonext) {
                        sonext = TAILQ_NEXT(sp, so_list);

                        /*
                         * Radar 5350314
                         * skip sockets thrown away by tcpdropdropblreq
                         * they will get cleanup by the garbage collection.
                         * otherwise, remove the incomp socket from the queue
                         * and let soabort trigger the appropriate cleanup.
                         */
                        if (sp->so_flags & SOF_OVERFLOW)
                                continue;

                        if (so->so_proto->pr_getlock != NULL) {
                                /*
                                 * Lock ordering for consistency with the
                                 * rest of the stack, we lock the socket
                                 * first and then grabb the head.
                                 */
                                socket_unlock(so, 0);
                                socket_lock(sp, 1);
                                socket_lock(so, 0);
                                socklock = 1;
                        }

                        TAILQ_REMOVE(&so->so_incomp, sp, so_list);
                        so->so_incqlen--;

                        if (sp->so_state & SS_INCOMP) {
                                sp->so_state &= ~SS_INCOMP;
                                sp->so_head = NULL;

                                (void) soabort(sp);
                        }

                        if (socklock)
                                socket_unlock(sp, 1);
                }

                while ((sp = TAILQ_FIRST(&so->so_comp)) != NULL) {
                        /* Dequeue from so_comp since sofree() won't do it */
                        TAILQ_REMOVE(&so->so_comp, sp, so_list);
                        so->so_qlen--;

                        if (so->so_proto->pr_getlock != NULL) {
                                socket_unlock(so, 0);
                                socket_lock(sp, 1);
                        }

                        if (sp->so_state & SS_COMP) {
                                sp->so_state &= ~SS_COMP;
                                sp->so_head = NULL;

                                (void) soabort(sp);
                        }

                        if (so->so_proto->pr_getlock != NULL) {
                                socket_unlock(sp, 1);
                                socket_lock(so, 0);
                        }
                }
        }
        if (so->so_pcb == NULL) {
                /* 3915887: mark the socket as ready for dealloc */
                so->so_flags |= SOF_PCBCLEARING;
                goto discard;
        }
        if (so->so_state & SS_ISCONNECTED) {
                if ((so->so_state & SS_ISDISCONNECTING) == 0) {
                        error = sodisconnectlocked(so);
                        if (error)
                                goto drop;
                }
                if (so->so_options & SO_LINGER) {
                        if ((so->so_state & SS_ISDISCONNECTING) &&
                            (so->so_state & SS_NBIO))
                                goto drop;
                        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;
                        while (so->so_state & SS_ISCONNECTED) {
                                ts.tv_sec = (so->so_linger/100);
                                ts.tv_nsec = (so->so_linger % 100) *
                                    NSEC_PER_USEC * 1000 * 10;
                                error = msleep((caddr_t)&so->so_timeo,
                                    mutex_held, PSOCK | PCATCH, "soclose", &ts);
                                if (error) {
                                        /*
                                         * It's OK when the time fires,
                                         * don't report an error
                                         */
                                        if (error == EWOULDBLOCK)
                                                error = 0;
                                        break;
                                }
                        }
                }
        }
drop:
        if (so->so_usecount == 0) {
                panic("soclose: usecount is zero so=%p\n", so);
                /* NOTREACHED */
        }
        if (so->so_pcb != NULL && !(so->so_flags & SOF_PCBCLEARING)) {
                int error2 = (*so->so_proto->pr_usrreqs->pru_detach)(so);
                if (error == 0)
                        error = error2;
        }
        if (so->so_usecount <= 0) {
                panic("soclose: usecount is zero so=%p\n", so);
                /* NOTREACHED */
        }
discard:
        if (so->so_pcb != NULL && !(so->so_flags & SOF_MP_SUBFLOW) &&
            (so->so_state & SS_NOFDREF)) {
                panic("soclose: NOFDREF");
                /* NOTREACHED */
        }
        so->so_state |= SS_NOFDREF;

        if (so->so_flags & SOF_MP_SUBFLOW)
                so->so_flags &= ~SOF_MP_SUBFLOW;

        if ((so->so_flags & SOF_KNOTE) != 0)
                KNOTE(&so->so_klist, SO_FILT_HINT_LOCKED);

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

        so->so_usecount--;
        sofree(so);
        return (error);
}

int
soclose(struct socket *so)
{
        int error = 0;
        socket_lock(so, 1);

        if (so->so_retaincnt == 0) {
                error = soclose_locked(so);
        } else {
                /*
                 * if the FD is going away, but socket is
                 * retained in kernel remove its reference
                 */
                so->so_usecount--;
                if (so->so_usecount < 2)
                        panic("soclose: retaincnt non null and so=%p "
                            "usecount=%d\n", so, so->so_usecount);
        }
        socket_unlock(so, 1);
        return (error);
}

/*
 * Must be called at splnet...
 */
/* Should already be locked */
int
soabort(struct socket *so)
{
        int error;

#ifdef MORE_LOCKING_DEBUG
        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);
#endif

        if ((so->so_flags & SOF_ABORTED) == 0) {
                so->so_flags |= SOF_ABORTED;
                error = (*so->so_proto->pr_usrreqs->pru_abort)(so);
                if (error) {
                        sofree(so);
                        return (error);
                }
        }
        return (0);
}

int
soacceptlock(struct socket *so, struct sockaddr **nam, int dolock)
{
        int error;

        if (dolock)
                socket_lock(so, 1);

        so_update_last_owner_locked(so, PROC_NULL);
        so_update_policy(so);
#if NECP
        so_update_necp_policy(so, NULL, NULL);
#endif /* NECP */

        if ((so->so_state & SS_NOFDREF) == 0)
                panic("soaccept: !NOFDREF");
        so->so_state &= ~SS_NOFDREF;
        error = (*so->so_proto->pr_usrreqs->pru_accept)(so, nam);

        if (dolock)
                socket_unlock(so, 1);
        return (error);
}

int
soaccept(struct socket *so, struct sockaddr **nam)
{
        return (soacceptlock(so, nam, 1));
}

int
soacceptfilter(struct socket *so)
{
        struct sockaddr *local = NULL, *remote = NULL;
        int error = 0;
        struct socket *head = so->so_head;

        /*
         * Hold the lock even if this socket has not been made visible
         * to the filter(s).  For sockets with global locks, this protects
         * against the head or peer going away
         */
        socket_lock(so, 1);
        if (sogetaddr_locked(so, &remote, 1) != 0 ||
            sogetaddr_locked(so, &local, 0) != 0) {
                so->so_state &= ~(SS_NOFDREF | SS_COMP);
                so->so_head = NULL;
                socket_unlock(so, 1);
                soclose(so);
                /* Out of resources; try it again next time */
                error = ECONNABORTED;
                goto done;
        }

        error = sflt_accept(head, so, local, remote);

        /*
         * If we get EJUSTRETURN from one of the filters, mark this socket
         * as inactive and return it anyway.  This newly accepted socket
         * will be disconnected later before we hand it off to the caller.
         */
        if (error == EJUSTRETURN) {
                error = 0;
                (void) sosetdefunct(current_proc(), so,
                    SHUTDOWN_SOCKET_LEVEL_DISCONNECT_INTERNAL, FALSE);
        }

        if (error != 0) {
                /*
                 * This may seem like a duplication to the above error
                 * handling part when we return ECONNABORTED, except
                 * the following is done while holding the lock since
                 * the socket has been exposed to the filter(s) earlier.
                 */
                so->so_state &= ~(SS_NOFDREF | SS_COMP);
                so->so_head = NULL;
                socket_unlock(so, 1);
                soclose(so);
                /* Propagate socket filter's error code to the caller */
        } else {
                socket_unlock(so, 1);
        }
done:
        /* Callee checks for NULL pointer */
        sock_freeaddr(remote);
        sock_freeaddr(local);
        return (error);
}

/*
 * Returns:     0                       Success
 *              EOPNOTSUPP              Operation not supported on socket
 *              EISCONN                 Socket is connected
 *      <pru_connect>:EADDRNOTAVAIL     Address not available.
 *      <pru_connect>:EINVAL            Invalid argument
 *      <pru_connect>:EAFNOSUPPORT      Address family not supported [notdef]
 *      <pru_connect>:EACCES            Permission denied
 *      <pru_connect>:EADDRINUSE        Address in use
 *      <pru_connect>:EAGAIN            Resource unavailable, try again
 *      <pru_connect>:EPERM             Operation not permitted
 *      <sf_connect_out>:???            [anything a filter writer might set]
 */
int
soconnectlock(struct socket *so, struct sockaddr *nam, int dolock)
{
        int error;
        struct proc *p = current_proc();

        if (dolock)
                socket_lock(so, 1);

        so_update_last_owner_locked(so, p);
        so_update_policy(so);

#if NECP
        so_update_necp_policy(so, NULL, nam);
#endif /* NECP */

        /*
         * If this is a listening socket or if this is a previously-accepted
         * socket that has been marked as inactive, reject the connect request.
         */
        if ((so->so_options & SO_ACCEPTCONN) || (so->so_flags & SOF_DEFUNCT)) {
                error = EOPNOTSUPP;
                if (so->so_flags & SOF_DEFUNCT) {
                        SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] "
                            "(%d)\n", __func__, proc_pid(p),
                            (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                            SOCK_DOM(so), SOCK_TYPE(so), error));
                }
                if (dolock)
                        socket_unlock(so, 1);
                return (error);
        }

        if ((so->so_restrictions & SO_RESTRICT_DENY_OUT) != 0) {
                if (dolock)
                        socket_unlock(so, 1);
                return (EPERM);
        }

        /*
         * If protocol is connection-based, can only connect once.
         * Otherwise, if connected, try to disconnect first.
         * This allows user to disconnect by connecting to, e.g.,
         * a null address.
         */
        if (so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING) &&
            ((so->so_proto->pr_flags & PR_CONNREQUIRED) ||
            (error = sodisconnectlocked(so)))) {
                error = EISCONN;
        } else {
                /*
                 * Run connect filter before calling protocol:
                 *  - non-blocking connect returns before completion;
                 */
                error = sflt_connectout(so, nam);
                if (error != 0) {
                        if (error == EJUSTRETURN)
                                error = 0;
                } else {
                        error = (*so->so_proto->pr_usrreqs->pru_connect)
                            (so, nam, p);
                }
        }
        if (dolock)
                socket_unlock(so, 1);
        return (error);
}

int
soconnect(struct socket *so, struct sockaddr *nam)
{
        return (soconnectlock(so, nam, 1));
}

/*
 * Returns:     0                       Success
 *      <pru_connect2>:EINVAL[AF_UNIX]
 *      <pru_connect2>:EPROTOTYPE[AF_UNIX]
 *      <pru_connect2>:???              [other protocol families]
 *
 * Notes:       <pru_connect2> is not supported by [TCP].
 */
int
soconnect2(struct socket *so1, struct socket *so2)
{
        int error;

        socket_lock(so1, 1);
        if (so2->so_proto->pr_lock)
                socket_lock(so2, 1);

        error = (*so1->so_proto->pr_usrreqs->pru_connect2)(so1, so2);

        socket_unlock(so1, 1);
        if (so2->so_proto->pr_lock)
                socket_unlock(so2, 1);
        return (error);
}

int
soconnectxlocked(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, uio_t auio, user_ssize_t *bytes_written)
{
        int error;

        so_update_last_owner_locked(so, p);
        so_update_policy(so);

        /*
         * If this is a listening socket or if this is a previously-accepted
         * socket that has been marked as inactive, reject the connect request.
         */
        if ((so->so_options & SO_ACCEPTCONN) || (so->so_flags & SOF_DEFUNCT)) {
                error = EOPNOTSUPP;
                if (so->so_flags & SOF_DEFUNCT) {
                        SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] "
                            "(%d)\n", __func__, proc_pid(p),
                            (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                            SOCK_DOM(so), SOCK_TYPE(so), error));
                }
                return (error);
        }

        if ((so->so_restrictions & SO_RESTRICT_DENY_OUT) != 0)
                return (EPERM);

        /*
         * If protocol is connection-based, can only connect once
         * unless PR_MULTICONN is set.  Otherwise, if connected,
         * try to disconnect first.  This allows user to disconnect
         * by connecting to, e.g., a null address.
         */
        if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) &&
            !(so->so_proto->pr_flags & PR_MULTICONN) &&
            ((so->so_proto->pr_flags & PR_CONNREQUIRED) ||
            (error = sodisconnectlocked(so)) != 0)) {
                error = EISCONN;
        } else {
                /*
                 * Run connect filter before calling protocol:
                 *  - non-blocking connect returns before completion;
                 */
                error = sflt_connectxout(so, dst_sl);
                if (error != 0) {
                        if (error == EJUSTRETURN)
                                error = 0;
                } else {
                        error = (*so->so_proto->pr_usrreqs->pru_connectx)
                            (so, src_sl, dst_sl, p, ifscope, aid, pcid,
                            flags, arg, arglen, auio, bytes_written);
                }
        }

        return (error);
}

int
sodisconnectlocked(struct socket *so)
{
        int error;

        if ((so->so_state & SS_ISCONNECTED) == 0) {
                error = ENOTCONN;
                goto bad;
        }
        if (so->so_state & SS_ISDISCONNECTING) {
                error = EALREADY;
                goto bad;
        }

        error = (*so->so_proto->pr_usrreqs->pru_disconnect)(so);
        if (error == 0)
                sflt_notify(so, sock_evt_disconnected, NULL);

bad:
        return (error);
}

/* Locking version */
int
sodisconnect(struct socket *so)
{
        int error;

        socket_lock(so, 1);
        error = sodisconnectlocked(so);
        socket_unlock(so, 1);
        return (error);
}

int
sodisconnectxlocked(struct socket *so, sae_associd_t aid, sae_connid_t cid)
{
        int error;

        /*
         * Call the protocol disconnectx handler; let it handle all
         * matters related to the connection state of this session.
         */
        error = (*so->so_proto->pr_usrreqs->pru_disconnectx)(so, aid, cid);
        if (error == 0) {
                /*
                 * The event applies only for the session, not for
                 * the disconnection of individual subflows.
                 */
                if (so->so_state & (SS_ISDISCONNECTING|SS_ISDISCONNECTED))
                        sflt_notify(so, sock_evt_disconnected, NULL);
        }
        return (error);
}

int
sodisconnectx(struct socket *so, sae_associd_t aid, sae_connid_t cid)
{
        int error;

        socket_lock(so, 1);
        error = sodisconnectxlocked(so, aid, cid);
        socket_unlock(so, 1);
        return (error);
}

int
sopeelofflocked(struct socket *so, sae_associd_t aid, struct socket **psop)
{
        return ((*so->so_proto->pr_usrreqs->pru_peeloff)(so, aid, psop));
}

#define SBLOCKWAIT(f)   (((f) & MSG_DONTWAIT) ? 0 : SBL_WAIT)

/*
 * sosendcheck will lock the socket buffer if it isn't locked and
 * verify that there is space for the data being inserted.
 *
 * Returns:     0                       Success
 *              EPIPE
 *      sblock:EWOULDBLOCK
 *      sblock:EINTR
 *      sbwait:EBADF
 *      sbwait:EINTR
 *      [so_error]:???
 */
int
sosendcheck(struct socket *so, struct sockaddr *addr, user_ssize_t resid,
    int32_t clen, int32_t atomic, int flags, int *sblocked,
    struct mbuf *control)
{
        int     error = 0;
        int32_t space;
        int     assumelock = 0;

restart:
        if (*sblocked == 0) {
                if ((so->so_snd.sb_flags & SB_LOCK) != 0 &&
                    so->so_send_filt_thread != 0 &&
                    so->so_send_filt_thread == current_thread()) {
                        /*
                         * We're being called recursively from a filter,
                         * allow this to continue. Radar 4150520.
                         * Don't set sblocked because we don't want
                         * to perform an unlock later.
                         */
                        assumelock = 1;
                } else {
                        error = sblock(&so->so_snd, SBLOCKWAIT(flags));
                        if (error) {
                                if (so->so_flags & SOF_DEFUNCT)
                                        goto defunct;
                                return (error);
                        }
                        *sblocked = 1;
                }
        }

        /*
         * If a send attempt is made on a socket that has been marked
         * as inactive (disconnected), reject the request.
         */
        if (so->so_flags & SOF_DEFUNCT) {
defunct:
                error = EPIPE;
                SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] (%d)\n",
                    __func__, proc_selfpid(),
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so), error));
                return (error);
        }

        if (so->so_state & SS_CANTSENDMORE) {
#if CONTENT_FILTER
                /*
                 * Can re-inject data of half closed connections
                 */
                if ((so->so_state & SS_ISDISCONNECTED) == 0 &&
                        so->so_snd.sb_cfil_thread == current_thread() &&
                        cfil_sock_data_pending(&so->so_snd) != 0)
                        CFIL_LOG(LOG_INFO,
                                "so %llx ignore SS_CANTSENDMORE",
                                (uint64_t)DEBUG_KERNEL_ADDRPERM(so));
                else
#endif /* CONTENT_FILTER */
                        return (EPIPE);
        }
        if (so->so_error) {
                error = so->so_error;
                so->so_error = 0;
                return (error);
        }

        if ((so->so_state & SS_ISCONNECTED) == 0) {
                if ((so->so_proto->pr_flags & PR_CONNREQUIRED) != 0) {
                        if (((so->so_state & SS_ISCONFIRMING) == 0) &&
                            (resid != 0 || clen == 0) &&
                            !(so->so_flags1 & SOF1_PRECONNECT_DATA)) {
#if MPTCP
                                /*
                                 * MPTCP Fast Join sends data before the
                                 * socket is truly connected.
                                 */
                                if ((so->so_flags & (SOF_MP_SUBFLOW |
                                        SOF_MPTCP_FASTJOIN)) !=
                                    (SOF_MP_SUBFLOW | SOF_MPTCP_FASTJOIN))
#endif /* MPTCP */
                                return (ENOTCONN);
                        }
                } else if (addr == 0 && !(flags&MSG_HOLD)) {
                        return ((so->so_proto->pr_flags & PR_CONNREQUIRED) ?
                            ENOTCONN : EDESTADDRREQ);
                }
        }

        if (so->so_flags & SOF_ENABLE_MSGS)
                space = msgq_sbspace(so, control);
        else
                space = sbspace(&so->so_snd);

        if (flags & MSG_OOB)
                space += 1024;
        if ((atomic && resid > so->so_snd.sb_hiwat) ||
            clen > so->so_snd.sb_hiwat)
                return (EMSGSIZE);

        if ((space < resid + clen &&
            (atomic || (space < (int32_t)so->so_snd.sb_lowat) ||
            space < clen)) ||
            (so->so_type == SOCK_STREAM && so_wait_for_if_feedback(so))) {
                /*
                 * don't block the connectx call when there's more data
                 * than can be copied.
                 */
                if (so->so_flags1 & SOF1_PRECONNECT_DATA) {
                        if (space == 0) {
                                return (EWOULDBLOCK);
                        }
                        if (space < (int32_t)so->so_snd.sb_lowat) {
                                return (0);
                        }
                }
                if ((so->so_state & SS_NBIO) || (flags & MSG_NBIO) ||
                    assumelock) {
                        return (EWOULDBLOCK);
                }
                sbunlock(&so->so_snd, TRUE);    /* keep socket locked */
                *sblocked = 0;
                error = sbwait(&so->so_snd);
                if (error) {
                        if (so->so_flags & SOF_DEFUNCT)
                                goto defunct;
                        return (error);
                }
                goto restart;
        }
        return (0);
}

/*
 * Send on a socket.
 * If send must go all at once and message is larger than
 * send buffering, then hard error.
 * Lock against other senders.
 * If must go all at once and not enough room now, then
 * inform user that this would block and do nothing.
 * Otherwise, if nonblocking, send as much as possible.
 * The data to be sent is described by "uio" if nonzero,
 * otherwise by the mbuf chain "top" (which must be null
 * if uio is not).  Data provided in mbuf chain must be small
 * enough to send all at once.
 *
 * Returns nonzero on error, timeout or signal; callers
 * must check for short counts if EINTR/ERESTART are returned.
 * Data and control buffers are freed on return.
 * Experiment:
 * MSG_HOLD: go thru most of sosend(), but just enqueue the mbuf
 * MSG_SEND: go thru as for MSG_HOLD on current fragment, then
 *  point at the mbuf chain being constructed and go from there.
 *
 * Returns:     0                       Success
 *              EOPNOTSUPP
 *              EINVAL
 *              ENOBUFS
 *      uiomove:EFAULT
 *      sosendcheck:EPIPE
 *      sosendcheck:EWOULDBLOCK
 *      sosendcheck:EINTR
 *      sosendcheck:EBADF
 *      sosendcheck:EINTR
 *      sosendcheck:???                 [value from so_error]
 *      <pru_send>:ECONNRESET[TCP]
 *      <pru_send>:EINVAL[TCP]
 *      <pru_send>:ENOBUFS[TCP]
 *      <pru_send>:EADDRINUSE[TCP]
 *      <pru_send>:EADDRNOTAVAIL[TCP]
 *      <pru_send>:EAFNOSUPPORT[TCP]
 *      <pru_send>:EACCES[TCP]
 *      <pru_send>:EAGAIN[TCP]
 *      <pru_send>:EPERM[TCP]
 *      <pru_send>:EMSGSIZE[TCP]
 *      <pru_send>:EHOSTUNREACH[TCP]
 *      <pru_send>:ENETUNREACH[TCP]
 *      <pru_send>:ENETDOWN[TCP]
 *      <pru_send>:ENOMEM[TCP]
 *      <pru_send>:ENOBUFS[TCP]
 *      <pru_send>:???[TCP]             [ignorable: mostly IPSEC/firewall/DLIL]
 *      <pru_send>:EINVAL[AF_UNIX]
 *      <pru_send>:EOPNOTSUPP[AF_UNIX]
 *      <pru_send>:EPIPE[AF_UNIX]
 *      <pru_send>:ENOTCONN[AF_UNIX]
 *      <pru_send>:EISCONN[AF_UNIX]
 *      <pru_send>:???[AF_UNIX]         [whatever a filter author chooses]
 *      <sf_data_out>:???               [whatever a filter author chooses]
 *
 * Notes:       Other <pru_send> returns depend on the protocol family; all
 *              <sf_data_out> returns depend on what the filter author causes
 *              their filter to return.
 */
int
sosend(struct socket *so, struct sockaddr *addr, struct uio *uio,
    struct mbuf *top, struct mbuf *control, int flags)
{
        struct mbuf **mp;
        struct mbuf *m, *freelist = NULL;
        user_ssize_t space, len, resid, orig_resid;
        int clen = 0, error, dontroute, mlen, sendflags;
        int atomic = sosendallatonce(so) || top;
        int sblocked = 0;
        struct proc *p = current_proc();
        struct mbuf *control_copy = NULL;
        uint16_t headroom = 0;
        boolean_t en_tracing = FALSE;

        if (uio != NULL)
                resid = uio_resid(uio);
        else
                resid = top->m_pkthdr.len;

        KERNEL_DEBUG((DBG_FNC_SOSEND | DBG_FUNC_START), so, resid,
            so->so_snd.sb_cc, so->so_snd.sb_lowat, so->so_snd.sb_hiwat);

        socket_lock(so, 1);

        /*
         * trace if tracing & network (vs. unix) sockets & and
         * non-loopback
         */
        if (ENTR_SHOULDTRACE &&
            (SOCK_CHECK_DOM(so, AF_INET) || SOCK_CHECK_DOM(so, AF_INET6))) {
                struct inpcb *inp = sotoinpcb(so);
                if (inp->inp_last_outifp != NULL &&
                    !(inp->inp_last_outifp->if_flags & IFF_LOOPBACK)) {
                        en_tracing = TRUE;
                        KERNEL_ENERGYTRACE(kEnTrActKernSockWrite, DBG_FUNC_START,
                            VM_KERNEL_ADDRPERM(so),
                            ((so->so_state & SS_NBIO) ? kEnTrFlagNonBlocking : 0),
                            (int64_t)resid);
                        orig_resid = resid;
                }
        }

        /*
         * Re-injection should not affect process accounting
         */
        if ((flags & MSG_SKIPCFIL) == 0) {
                so_update_last_owner_locked(so, p);
                so_update_policy(so);

#if NECP
                so_update_necp_policy(so, NULL, addr);
#endif /* NECP */
        }

        if (so->so_type != SOCK_STREAM && (flags & MSG_OOB) != 0) {
                error = EOPNOTSUPP;
                socket_unlock(so, 1);
                goto out;
        }

        /*
         * In theory resid should be unsigned.
         * However, space must be signed, as it might be less than 0
         * if we over-committed, and we must use a signed comparison
         * of space and resid.  On the other hand, a negative resid
         * causes us to loop sending 0-length segments to the protocol.
         *
         * Usually, MSG_EOR isn't used on SOCK_STREAM type sockets.
         * But it will be used by sockets doing message delivery.
         *
         * Note: We limit resid to be a positive int value as we use
         * imin() to set bytes_to_copy -- radr://14558484
         */
        if (resid < 0 || resid > INT_MAX || (so->so_type == SOCK_STREAM &&
            !(so->so_flags & SOF_ENABLE_MSGS) && (flags & MSG_EOR))) {
                error = EINVAL;
                socket_unlock(so, 1);
                goto out;
        }

        dontroute = (flags & MSG_DONTROUTE) &&
            (so->so_options & SO_DONTROUTE) == 0 &&
            (so->so_proto->pr_flags & PR_ATOMIC);
        OSIncrementAtomicLong(&p->p_stats->p_ru.ru_msgsnd);

        if (control != NULL)
                clen = control->m_len;

        if (soreserveheadroom != 0)
                headroom = so->so_pktheadroom;

        do {
                error = sosendcheck(so, addr, resid, clen, atomic, flags,
                    &sblocked, control);
                if (error)
                        goto release;

                mp = &top;
                if (so->so_flags & SOF_ENABLE_MSGS)
                        space = msgq_sbspace(so, control);
                else
                        space = sbspace(&so->so_snd) - clen;
                space += ((flags & MSG_OOB) ? 1024 : 0);

                do {
                        if (uio == NULL) {
                                /*
                                 * Data is prepackaged in "top".
                                 */
                                resid = 0;
                                if (flags & MSG_EOR)
                                        top->m_flags |= M_EOR;
                        } else {
                                int chainlength;
                                int bytes_to_copy;
                                boolean_t jumbocl;
                                boolean_t bigcl;
                                int bytes_to_alloc;

                                bytes_to_copy = imin(resid, space);

                                bytes_to_alloc = bytes_to_copy;
                                if (top == NULL)
                                        bytes_to_alloc += headroom;

                                if (sosendminchain > 0)
                                        chainlength = 0;
                                else
                                        chainlength = sosendmaxchain;

                                /*
                                 * Use big 4 KB cluster when the outgoing interface
                                 * does not prefer 2 KB clusters
                                 */
                                bigcl = !(so->so_flags1 & SOF1_IF_2KCL) ||
                                    sosendbigcl_ignore_capab;

                                /*
                                 * Attempt to use larger than system page-size
                                 * clusters for large writes only if there is
                                 * a jumbo cluster pool and if the socket is
                                 * marked accordingly.
                                 */
                                jumbocl = sosendjcl && njcl > 0 &&
                                    ((so->so_flags & SOF_MULTIPAGES) ||
                                    sosendjcl_ignore_capab) &&
                                    bigcl;

                                socket_unlock(so, 0);

                                do {
                                        int num_needed;
                                        int hdrs_needed = (top == NULL) ? 1 : 0;

                                        /*
                                         * try to maintain a local cache of mbuf
                                         * clusters needed to complete this
                                         * write the list is further limited to
                                         * the number that are currently needed
                                         * to fill the socket this mechanism
                                         * allows a large number of mbufs/
                                         * clusters to be grabbed under a single
                                         * mbuf lock... if we can't get any
                                         * clusters, than fall back to trying
                                         * for mbufs if we fail early (or
                                         * miscalcluate the number needed) make
                                         * sure to release any clusters we
                                         * haven't yet consumed.
                                         */
                                        if (freelist == NULL &&
                                            bytes_to_alloc > MBIGCLBYTES &&
                                            jumbocl) {
                                                num_needed =
                                                    bytes_to_alloc / M16KCLBYTES;

                                                if ((bytes_to_alloc -
                                                    (num_needed * M16KCLBYTES))
                                                    >= MINCLSIZE)
                                                        num_needed++;

                                                freelist =
                                                    m_getpackets_internal(
                                                    (unsigned int *)&num_needed,
                                                    hdrs_needed, M_WAIT, 0,
                                                    M16KCLBYTES);
                                                /*
                                                 * Fall back to 4K cluster size
                                                 * if allocation failed
                                                 */
                                        }

                                        if (freelist == NULL &&
                                            bytes_to_alloc > MCLBYTES &&
                                            bigcl) {
                                                num_needed =
                                                    bytes_to_alloc / MBIGCLBYTES;

                                                if ((bytes_to_alloc -
                                                    (num_needed * MBIGCLBYTES)) >=
                                                    MINCLSIZE)
                                                        num_needed++;

                                                freelist =
                                                    m_getpackets_internal(
                                                    (unsigned int *)&num_needed,
                                                    hdrs_needed, M_WAIT, 0,
                                                    MBIGCLBYTES);
                                                /*
                                                 * Fall back to cluster size
                                                 * if allocation failed
                                                 */
                                        }

                                        /*
                                         * Allocate a cluster as we want to
                                         * avoid to split the data in more
                                         * that one segment and using MINCLSIZE
                                         * would lead us to allocate two mbufs
                                         */
                                        if (soreserveheadroom != 0 &&
                                            freelist == NULL &&
                                            ((top == NULL &&
                                            bytes_to_alloc > _MHLEN) ||
                                            bytes_to_alloc > _MLEN)) {
                                                num_needed = ROUNDUP(bytes_to_alloc, MCLBYTES) /
                                                    MCLBYTES;
                                                freelist =
                                                    m_getpackets_internal(
                                                    (unsigned int *)&num_needed,
                                                    hdrs_needed, M_WAIT, 0,
                                                    MCLBYTES);
                                                /*
                                                 * Fall back to a single mbuf
                                                 * if allocation failed
                                                 */
                                        } else if (freelist == NULL &&
                                            bytes_to_alloc > MINCLSIZE) {
                                                num_needed =
                                                    bytes_to_alloc / MCLBYTES;

                                                if ((bytes_to_alloc -
                                                    (num_needed * MCLBYTES)) >=
                                                    MINCLSIZE)
                                                        num_needed++;

                                                freelist =
                                                    m_getpackets_internal(
                                                    (unsigned int *)&num_needed,
                                                    hdrs_needed, M_WAIT, 0,
                                                    MCLBYTES);
                                                /*
                                                 * Fall back to a single mbuf
                                                 * if allocation failed
                                                 */
                                        }
                                        /*
                                         * For datagram protocols, leave
                                         * headroom for protocol headers
                                         * in the first cluster of the chain
                                         */
                                        if (freelist != NULL && atomic &&
                                            top == NULL && headroom > 0) {
                                                freelist->m_data += headroom;
                                        }
                                        
                                        /*
                                         * Fall back to regular mbufs without
                                         * reserving the socket headroom
                                         */
                                        if (freelist == NULL) {
                                                if (top == NULL)
                                                        MGETHDR(freelist,
                                                            M_WAIT, MT_DATA);
                                                else
                                                        MGET(freelist,
                                                            M_WAIT, MT_DATA);

                                                if (freelist == NULL) {
                                                        error = ENOBUFS;
                                                        socket_lock(so, 0);
                                                        goto release;
                                                }
                                                /*
                                                 * For datagram protocols,
                                                 * leave room for protocol
                                                 * headers in first mbuf.
                                                 */
                                                if (atomic && top == NULL &&
                                                    bytes_to_copy < MHLEN) {
                                                        MH_ALIGN(freelist,
                                                            bytes_to_copy);
                                                }
                                        }
                                        m = freelist;
                                        freelist = m->m_next;
                                        m->m_next = NULL;

                                        if ((m->m_flags & M_EXT))
                                                mlen = m->m_ext.ext_size -
                                                    m_leadingspace(m);
                                        else if ((m->m_flags & M_PKTHDR))
                                                mlen =
                                                    MHLEN - m_leadingspace(m);
                                        else
                                                mlen = MLEN - m_leadingspace(m);
                                        len = imin(mlen, bytes_to_copy);

                                        chainlength += len;

                                        space -= len;

                                        error = uiomove(mtod(m, caddr_t),
                                            len, uio);

                                        resid = uio_resid(uio);

                                        m->m_len = len;
                                        *mp = m;
                                        top->m_pkthdr.len += len;
                                        if (error)
                                                break;
                                        mp = &m->m_next;
                                        if (resid <= 0) {
                                                if (flags & MSG_EOR)
                                                        top->m_flags |= M_EOR;
                                                break;
                                        }
                                        bytes_to_copy = min(resid, space);

                                } while (space > 0 &&
                                    (chainlength < sosendmaxchain || atomic ||
                                    resid < MINCLSIZE));

                                socket_lock(so, 0);

                                if (error)
                                        goto release;
                        }

                        if (flags & (MSG_HOLD|MSG_SEND)) {
                                /* Enqueue for later, go away if HOLD */
                                struct mbuf *mb1;
                                if (so->so_temp && (flags & MSG_FLUSH)) {
                                        m_freem(so->so_temp);
                                        so->so_temp = NULL;
                                }
                                if (so->so_temp)
                                        so->so_tail->m_next = top;
                                else
                                        so->so_temp = top;
                                mb1 = top;
                                while (mb1->m_next)
                                        mb1 = mb1->m_next;
                                so->so_tail = mb1;
                                if (flags & MSG_HOLD) {
                                        top = NULL;
                                        goto release;
                                }
                                top = so->so_temp;
                        }
                        if (dontroute)
                                so->so_options |= SO_DONTROUTE;

                        /*
                         * Compute flags here, for pru_send and NKEs
                         *
                         * If the user set MSG_EOF, the protocol
                         * understands this flag and nothing left to
                         * send then use PRU_SEND_EOF instead of PRU_SEND.
                         */
                        sendflags = (flags & MSG_OOB) ? PRUS_OOB :
                            ((flags & MSG_EOF) &&
                            (so->so_proto->pr_flags & PR_IMPLOPCL) &&
                            (resid <= 0)) ? PRUS_EOF :
                            /* If there is more to send set PRUS_MORETOCOME */
                            (resid > 0 && space > 0) ? PRUS_MORETOCOME : 0;

                        if ((flags & MSG_SKIPCFIL) == 0) {
                                /*
                                 * Socket filter processing
                                 */
                                error = sflt_data_out(so, addr, &top,
                                    &control, (sendflags & MSG_OOB) ?
                                    sock_data_filt_flag_oob : 0);
                                if (error) {
                                        if (error == EJUSTRETURN) {
                                                error = 0;
                                                clen = 0;
                                                control = NULL;
                                                top = NULL;
                                        }
                                        goto release;
                                }
#if CONTENT_FILTER
                                /*
                                 * Content filter processing
                                 */
                                error = cfil_sock_data_out(so, addr, top,
                                    control, (sendflags & MSG_OOB) ?
                                    sock_data_filt_flag_oob : 0);
                                if (error) {
                                        if (error == EJUSTRETURN) {
                                                error = 0;
                                                clen = 0;
                                                control = NULL;
                                                top = NULL;
                                                }
                                        goto release;
                                }
#endif /* CONTENT_FILTER */
                        }
                        if (so->so_flags & SOF_ENABLE_MSGS) {
                                /*
                                 * Make a copy of control mbuf,
                                 * so that msg priority can be
                                 * passed to subsequent mbufs.
                                 */
                                control_copy = m_dup(control, M_NOWAIT);
                        }
                        error = (*so->so_proto->pr_usrreqs->pru_send)
                            (so, sendflags, top, addr, control, p);

                        if (flags & MSG_SEND)
                                so->so_temp = NULL;

                        if (dontroute)
                                so->so_options &= ~SO_DONTROUTE;

                        clen = 0;
                        control = control_copy;
                        control_copy = NULL;
                        top = NULL;
                        mp = &top;
                        if (error)
                                goto release;
                } while (resid && space > 0);
        } while (resid);

release:
        if (sblocked)
                sbunlock(&so->so_snd, FALSE);   /* will unlock socket */
        else
                socket_unlock(so, 1);
out:
        if (top != NULL)
                m_freem(top);
        if (control != NULL)
                m_freem(control);
        if (freelist != NULL)
                m_freem_list(freelist);
        if (control_copy != NULL)
                m_freem(control_copy);

        /*
         * One write has been done. This was enough. Get back to "normal"
         * behavior.
         */
        if (so->so_flags1 & SOF1_PRECONNECT_DATA)
                so->so_flags1 &= ~SOF1_PRECONNECT_DATA;

        if (en_tracing) {
                /* resid passed here is the bytes left in uio */
                KERNEL_ENERGYTRACE(kEnTrActKernSockWrite, DBG_FUNC_END,
                    VM_KERNEL_ADDRPERM(so),
                    ((error == EWOULDBLOCK) ? kEnTrFlagNoWork : 0),
                    (int64_t)(orig_resid - resid));
        }
        KERNEL_DEBUG(DBG_FNC_SOSEND | DBG_FUNC_END, so, resid,
            so->so_snd.sb_cc, space, error);

        return (error);
}

/*
 * Supported only connected sockets (no address) without ancillary data
 * (control mbuf) for atomic protocols
 */
int
sosend_list(struct socket *so, struct uio **uioarray, u_int uiocnt, int flags)
{
        struct mbuf *m, *freelist = NULL;
        user_ssize_t len, resid;
        int error, dontroute, mlen;
        int atomic = sosendallatonce(so);
        int sblocked = 0;
        struct proc *p = current_proc();
        u_int uiofirst = 0;
        u_int uiolast = 0;
        struct mbuf *top = NULL;
        uint16_t headroom = 0;
        boolean_t bigcl;

        KERNEL_DEBUG((DBG_FNC_SOSEND_LIST | DBG_FUNC_START), so, uiocnt,
            so->so_snd.sb_cc, so->so_snd.sb_lowat, so->so_snd.sb_hiwat);

        if (so->so_type != SOCK_DGRAM) {
                error = EINVAL;
                goto out;
        }
        if (atomic == 0) {
                error = EINVAL;
                goto out;
        }
        if (so->so_proto->pr_usrreqs->pru_send_list == NULL) {
                error = EPROTONOSUPPORT;
                goto out;
        }
        if (flags & ~(MSG_DONTWAIT | MSG_NBIO)) {
                error = EINVAL;
                goto out;
        }
        resid = uio_array_resid(uioarray, uiocnt);

        /*
         * In theory resid should be unsigned.
         * However, space must be signed, as it might be less than 0
         * if we over-committed, and we must use a signed comparison
         * of space and resid.  On the other hand, a negative resid
         * causes us to loop sending 0-length segments to the protocol.
         *
         * Note: We limit resid to be a positive int value as we use
         * imin() to set bytes_to_copy -- radr://14558484
         */
        if (resid < 0 || resid > INT_MAX) {
                error = EINVAL;
                goto out;
        }

        socket_lock(so, 1);
        so_update_last_owner_locked(so, p);
        so_update_policy(so);

#if NECP
        so_update_necp_policy(so, NULL, NULL);
#endif /* NECP */

        dontroute = (flags & MSG_DONTROUTE) &&
            (so->so_options & SO_DONTROUTE) == 0 &&
            (so->so_proto->pr_flags & PR_ATOMIC);
        OSIncrementAtomicLong(&p->p_stats->p_ru.ru_msgsnd);

        error = sosendcheck(so, NULL, resid, 0, atomic, flags,
            &sblocked, NULL);
        if (error)
                goto release;

        /*
         * Use big 4 KB clusters when the outgoing interface does not prefer
         * 2 KB clusters
         */
        bigcl = !(so->so_flags1 & SOF1_IF_2KCL) || sosendbigcl_ignore_capab;

        if (soreserveheadroom != 0)
                headroom = so->so_pktheadroom;

        do {
                int i;
                int num_needed = 0;
                int chainlength;
                size_t maxpktlen = 0;
                int bytes_to_alloc;

                if (sosendminchain > 0)
                        chainlength = 0;
                else
                        chainlength = sosendmaxchain;

                socket_unlock(so, 0);

                /*
                 * Find a set of uio that fit in a reasonable number
                 * of mbuf packets
                 */
                for (i = uiofirst; i < uiocnt; i++) {
                        struct uio *auio = uioarray[i];

                        len = uio_resid(auio);

                        /* Do nothing for empty messages */
                        if (len == 0)
                                continue;

                        num_needed += 1;
                        uiolast += 1;

                        if (len > maxpktlen)
                                maxpktlen = len;

                        chainlength += len;
                        if (chainlength > sosendmaxchain)
                                break;
                }
                /*
                 * Nothing left to send
                 */
                if (num_needed == 0) {
                        socket_lock(so, 0);
                        break;
                }
                /*
                 * Allocate buffer large enough to include headroom space for
                 * network and link header
                 * 
                 */
                bytes_to_alloc = maxpktlen + headroom;

                /*
                 * Allocate a single contiguous buffer of the smallest available
                 * size when possible
                 */
                if (bytes_to_alloc > MCLBYTES &&
                    bytes_to_alloc <= MBIGCLBYTES && bigcl) {
                        freelist = m_getpackets_internal(
                            (unsigned int *)&num_needed,
                            num_needed, M_WAIT, 1,
                            MBIGCLBYTES);
                } else if (bytes_to_alloc > _MHLEN &&
                    bytes_to_alloc <= MCLBYTES) {
                        freelist = m_getpackets_internal(
                            (unsigned int *)&num_needed,
                            num_needed, M_WAIT, 1,
                            MCLBYTES);
                } else {
                        freelist = m_allocpacket_internal(
                            (unsigned int *)&num_needed,
                            bytes_to_alloc, NULL, M_WAIT, 1, 0);
                }
                
                if (freelist == NULL) {
                        socket_lock(so, 0);
                        error = ENOMEM;
                        goto release;
                }
                /*
                 * Copy each uio of the set into its own mbuf packet
                 */
                for (i = uiofirst, m = freelist;
                    i < uiolast && m != NULL;
                    i++) {
                        int bytes_to_copy;
                        struct mbuf *n;
                        struct uio *auio = uioarray[i];

                        bytes_to_copy = uio_resid(auio);

                        /* Do nothing for empty messages */
                        if (bytes_to_copy == 0)
                                continue;
                        /*
                         * Leave headroom for protocol headers
                         * in the first mbuf of the chain
                         */
                        m->m_data += headroom;

                        for (n = m; n != NULL; n = n->m_next) {
                                if ((m->m_flags & M_EXT))
                                        mlen = m->m_ext.ext_size -
                                            m_leadingspace(m);
                                else if ((m->m_flags & M_PKTHDR))
                                        mlen =
                                            MHLEN - m_leadingspace(m);
                                else
                                        mlen = MLEN - m_leadingspace(m);
                                len = imin(mlen, bytes_to_copy);

                                /*
                                 * Note: uiomove() decrements the iovec
                                 * length
                                 */
                                error = uiomove(mtod(n, caddr_t),
                                    len, auio);
                                if (error != 0)
                                        break;
                                n->m_len = len;
                                m->m_pkthdr.len += len;

                                VERIFY(m->m_pkthdr.len <= maxpktlen);

                                bytes_to_copy -= len;
                                resid -= len;
                        }
                        if (m->m_pkthdr.len == 0) {
                                printf(
                                    "%s:%d so %llx pkt %llx type %u len null\n",
                                    __func__, __LINE__,
                                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                                    (uint64_t)DEBUG_KERNEL_ADDRPERM(m),
                                    m->m_type);
                        }
                        if (error != 0)
                                break;
                        m = m->m_nextpkt;
                }

                socket_lock(so, 0);

                if (error)
                        goto release;
                top = freelist;
                freelist = NULL;

                if (dontroute)
                        so->so_options |= SO_DONTROUTE;

                if ((flags & MSG_SKIPCFIL) == 0) {
                        struct mbuf **prevnextp = NULL;

                        for (i = uiofirst, m = top;
                            i < uiolast && m != NULL;
                            i++) {
                                struct mbuf *nextpkt = m->m_nextpkt;

                                /*
                                 * Socket filter processing
                                 */
                                error = sflt_data_out(so, NULL, &m,
                                    NULL, 0);
                                if (error != 0 && error != EJUSTRETURN)
                                        goto release;

#if CONTENT_FILTER
                                if (error == 0) {
                                        /*
                                         * Content filter processing
                                         */
                                        error = cfil_sock_data_out(so, NULL, m,
                                            NULL, 0);
                                        if (error != 0 && error != EJUSTRETURN)
                                                goto release;
                                }
#endif /* CONTENT_FILTER */
                                /*
                                 * Remove packet from the list when
                                 * swallowed by a filter
                                 */
                                if (error == EJUSTRETURN) {
                                        error = 0;
                                        if (prevnextp != NULL)
                                                *prevnextp = nextpkt;
                                        else
                                                top = nextpkt;
                                }

                                m = nextpkt;
                                if (m != NULL)
                                        prevnextp = &m->m_nextpkt;
                        }
                }
                if (top != NULL)
                        error = (*so->so_proto->pr_usrreqs->pru_send_list)
                            (so, 0, top, NULL, NULL, p);

                if (dontroute)
                        so->so_options &= ~SO_DONTROUTE;

                top = NULL;
                uiofirst = uiolast;
        } while (resid > 0 && error == 0);
release:
        if (sblocked)
                sbunlock(&so->so_snd, FALSE);   /* will unlock socket */
        else
                socket_unlock(so, 1);
out:
        if (top != NULL)
                m_freem(top);
        if (freelist != NULL)
                m_freem_list(freelist);

        KERNEL_DEBUG(DBG_FNC_SOSEND_LIST | DBG_FUNC_END, so, resid,
            so->so_snd.sb_cc, 0, error);

        return (error);
}

/*
 * May return ERESTART when packet is dropped by MAC policy check
 */
static int
soreceive_addr(struct proc *p, struct socket *so, struct sockaddr **psa,
    int flags, struct mbuf **mp, struct mbuf **nextrecordp, int canwait)
{
        int error = 0;
        struct mbuf *m = *mp;
        struct mbuf *nextrecord = *nextrecordp;

        KASSERT(m->m_type == MT_SONAME, ("receive 1a"));
#if CONFIG_MACF_SOCKET_SUBSET
        /*
         * Call the MAC framework for policy checking if we're in
         * the user process context and the socket isn't connected.
         */
        if (p != kernproc && !(so->so_state & SS_ISCONNECTED)) {
                struct mbuf *m0 = m;
                /*
                 * Dequeue this record (temporarily) from the receive
                 * list since we're about to drop the socket's lock
                 * where a new record may arrive and be appended to
                 * the list.  Upon MAC policy failure, the record
                 * will be freed.  Otherwise, we'll add it back to
                 * the head of the list.  We cannot rely on SB_LOCK
                 * because append operation uses the socket's lock.
                 */
                do {
                        m->m_nextpkt = NULL;
                        sbfree(&so->so_rcv, m);
                        m = m->m_next;
                } while (m != NULL);
                m = m0;
                so->so_rcv.sb_mb = nextrecord;
                SB_EMPTY_FIXUP(&so->so_rcv);
                SBLASTRECORDCHK(&so->so_rcv, "soreceive 1a");
                SBLASTMBUFCHK(&so->so_rcv, "soreceive 1a");
                socket_unlock(so, 0);

                if (mac_socket_check_received(proc_ucred(p), so,
                    mtod(m, struct sockaddr *)) != 0) {
                        /*
                         * MAC policy failure; free this record and
                         * process the next record (or block until
                         * one is available).  We have adjusted sb_cc
                         * and sb_mbcnt above so there is no need to
                         * call sbfree() again.
                         */
                        m_freem(m);
                        /*
                         * Clear SB_LOCK but don't unlock the socket.
                         * Process the next record or wait for one.
                         */
                        socket_lock(so, 0);
                        sbunlock(&so->so_rcv, TRUE); /* stay locked */
                        error = ERESTART;
                        goto done;
                }
                socket_lock(so, 0);
                /*
                 * If the socket has been defunct'd, drop it.
                 */
                if (so->so_flags & SOF_DEFUNCT) {
                        m_freem(m);
                        error = ENOTCONN;
                        goto done;
                }
                /*
                 * Re-adjust the socket receive list and re-enqueue
                 * the record in front of any packets which may have
                 * been appended while we dropped the lock.
                 */
                for (m = m0; m->m_next != NULL; m = m->m_next)
                        sballoc(&so->so_rcv, m);
                sballoc(&so->so_rcv, m);
                if (so->so_rcv.sb_mb == NULL) {
                        so->so_rcv.sb_lastrecord = m0;
                        so->so_rcv.sb_mbtail = m;
                }
                m = m0;
                nextrecord = m->m_nextpkt = so->so_rcv.sb_mb;
                so->so_rcv.sb_mb = m;
                SBLASTRECORDCHK(&so->so_rcv, "soreceive 1b");
                SBLASTMBUFCHK(&so->so_rcv, "soreceive 1b");
        }
#endif /* CONFIG_MACF_SOCKET_SUBSET */
        if (psa != NULL) {
                *psa = dup_sockaddr(mtod(m, struct sockaddr *), canwait);
                if ((*psa == NULL) && (flags & MSG_NEEDSA)) {
                        error = EWOULDBLOCK;
                        goto done;
                }
        }
        if (flags & MSG_PEEK) {
                m = m->m_next;
        } else {
                sbfree(&so->so_rcv, m);
                if (m->m_next == NULL && so->so_rcv.sb_cc != 0) {
                        panic("%s: about to create invalid socketbuf",
                            __func__);
                        /* NOTREACHED */
                }
                MFREE(m, so->so_rcv.sb_mb);
                m = so->so_rcv.sb_mb;
                if (m != NULL) {
                        m->m_nextpkt = nextrecord;
                } else {
                        so->so_rcv.sb_mb = nextrecord;
                        SB_EMPTY_FIXUP(&so->so_rcv);
                }
        }
done:
        *mp = m;
        *nextrecordp = nextrecord;

        return (error);
}

/*
 * Process one or more MT_CONTROL mbufs present before any data mbufs
 * in the first mbuf chain on the socket buffer.  If MSG_PEEK, we
 * just copy the data; if !MSG_PEEK, we call into the protocol to
 * perform externalization.
 */
static int
soreceive_ctl(struct socket *so, struct mbuf **controlp, int flags,
    struct mbuf **mp, struct mbuf **nextrecordp)
{
        int error = 0;
        struct mbuf *cm = NULL, *cmn;
        struct mbuf **cme = &cm;
        struct sockbuf *sb_rcv = &so->so_rcv;
        struct mbuf **msgpcm = NULL;
        struct mbuf *m = *mp;
        struct mbuf *nextrecord = *nextrecordp;
        struct protosw *pr = so->so_proto;

        /*
         * Externalizing the control messages would require us to
         * drop the socket's lock below.  Once we re-acquire the
         * lock, the mbuf chain might change.  In order to preserve
         * consistency, we unlink all control messages from the
         * first mbuf chain in one shot and link them separately
         * onto a different chain.
         */
        do {
                if (flags & MSG_PEEK) {
                        if (controlp != NULL) {
                                if (*controlp == NULL) {
                                        msgpcm = controlp;
                                }
                                *controlp = m_copy(m, 0, m->m_len);

                                /*
                                 * If we failed to allocate an mbuf,
                                 * release any previously allocated
                                 * mbufs for control data. Return
                                 * an error. Keep the mbufs in the
                                 * socket as this is using
                                 * MSG_PEEK flag.
                                 */
                                if (*controlp == NULL) {
                                        m_freem(*msgpcm);
                                        error = ENOBUFS;
                                        goto done;
                                }
                                controlp = &(*controlp)->m_next;
                        }
                        m = m->m_next;
                } else {
                        m->m_nextpkt = NULL;
                        sbfree(sb_rcv, m);
                        sb_rcv->sb_mb = m->m_next;
                        m->m_next = NULL;
                        *cme = m;
                        cme = &(*cme)->m_next;
                        m = sb_rcv->sb_mb;
                }
        } while (m != NULL && m->m_type == MT_CONTROL);

        if (!(flags & MSG_PEEK)) {
                if (sb_rcv->sb_mb != NULL) {
                        sb_rcv->sb_mb->m_nextpkt = nextrecord;
                } else {
                        sb_rcv->sb_mb = nextrecord;
                        SB_EMPTY_FIXUP(sb_rcv);
                }
                if (nextrecord == NULL)
                        sb_rcv->sb_lastrecord = m;
        }

        SBLASTRECORDCHK(&so->so_rcv, "soreceive ctl");
        SBLASTMBUFCHK(&so->so_rcv, "soreceive ctl");

        while (cm != NULL) {
                int cmsg_type;

                cmn = cm->m_next;
                cm->m_next = NULL;
                cmsg_type = mtod(cm, struct cmsghdr *)->cmsg_type;

                /*
                 * Call the protocol to externalize SCM_RIGHTS message
                 * and return the modified message to the caller upon
                 * success.  Otherwise, all other control messages are
                 * returned unmodified to the caller.  Note that we
                 * only get into this loop if MSG_PEEK is not set.
                 */
                if (pr->pr_domain->dom_externalize != NULL &&
                    cmsg_type == SCM_RIGHTS) {
                        /*
                         * Release socket lock: see 3903171.  This
                         * would also allow more records to be appended
                         * to the socket buffer.  We still have SB_LOCK
                         * set on it, so we can be sure that the head
                         * of the mbuf chain won't change.
                         */
                        socket_unlock(so, 0);
                        error = (*pr->pr_domain->dom_externalize)(cm);
                        socket_lock(so, 0);
                } else {
                        error = 0;
                }

                if (controlp != NULL && error == 0) {
                        *controlp = cm;
                        controlp = &(*controlp)->m_next;
                } else {
                        (void) m_free(cm);
                }
                cm = cmn;
        }
        /*
         * Update the value of nextrecord in case we received new
         * records when the socket was unlocked above for
         * externalizing SCM_RIGHTS.
         */
        if (m != NULL)
                nextrecord = sb_rcv->sb_mb->m_nextpkt;
        else
                nextrecord = sb_rcv->sb_mb;

done:
        *mp = m;
        *nextrecordp = nextrecord;

        return (error);
}

/*
 * Implement receive operations on a socket.
 * We depend on the way that records are added to the sockbuf
 * by sbappend*.  In particular, each record (mbufs linked through m_next)
 * must begin with an address if the protocol so specifies,
 * followed by an optional mbuf or mbufs containing ancillary data,
 * and then zero or more mbufs of data.
 * In order to avoid blocking network interrupts for the entire time here,
 * we splx() while doing the actual copy to user space.
 * Although the sockbuf is locked, new data may still be appended,
 * and thus we must maintain consistency of the sockbuf during that time.
 *
 * The caller may receive the data as a single mbuf chain by supplying
 * an mbuf **mp0 for use in returning the chain.  The uio is then used
 * only for the count in uio_resid.
 *
 * Returns:     0                       Success
 *              ENOBUFS
 *              ENOTCONN
 *              EWOULDBLOCK
 *      uiomove:EFAULT
 *      sblock:EWOULDBLOCK
 *      sblock:EINTR
 *      sbwait:EBADF
 *      sbwait:EINTR
 *      sodelayed_copy:EFAULT
 *      <pru_rcvoob>:EINVAL[TCP]
 *      <pru_rcvoob>:EWOULDBLOCK[TCP]
 *      <pru_rcvoob>:???
 *      <pr_domain->dom_externalize>:EMSGSIZE[AF_UNIX]
 *      <pr_domain->dom_externalize>:ENOBUFS[AF_UNIX]
 *      <pr_domain->dom_externalize>:???
 *
 * Notes:       Additional return values from calls through <pru_rcvoob> and
 *              <pr_domain->dom_externalize> depend on protocols other than
 *              TCP or AF_UNIX, which are documented above.
 */
int
soreceive(struct socket *so, struct sockaddr **psa, struct uio *uio,
    struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
{
        struct mbuf *m, **mp, *ml = NULL;
        struct mbuf *nextrecord, *free_list;
        int flags, error, offset;
        user_ssize_t len;
        struct protosw *pr = so->so_proto;
        int moff, type = 0;
        user_ssize_t orig_resid = uio_resid(uio);
        user_ssize_t delayed_copy_len;
        int can_delay;
        int need_event;
        struct proc *p = current_proc();
        boolean_t en_tracing = FALSE;

        /*
         * Sanity check on the length passed by caller as we are making 'int'
         * comparisons
         */
        if (orig_resid < 0 || orig_resid > INT_MAX)
                return (EINVAL);

        KERNEL_DEBUG(DBG_FNC_SORECEIVE | DBG_FUNC_START, so,
            uio_resid(uio), so->so_rcv.sb_cc, so->so_rcv.sb_lowat,
            so->so_rcv.sb_hiwat);

        socket_lock(so, 1);
        so_update_last_owner_locked(so, p);
        so_update_policy(so);

#ifdef MORE_LOCKING_DEBUG
        if (so->so_usecount == 1) {
                panic("%s: so=%x no other reference on socket\n", __func__, so);
                /* NOTREACHED */
        }
#endif
        mp = mp0;
        if (psa != NULL)
                *psa = NULL;
        if (controlp != NULL)
                *controlp = NULL;
        if (flagsp != NULL)
                flags = *flagsp &~ MSG_EOR;
        else
                flags = 0;

        /*
         * If a recv attempt is made on a previously-accepted socket
         * that has been marked as inactive (disconnected), reject
         * the request.
         */
        if (so->so_flags & SOF_DEFUNCT) {
                struct sockbuf *sb = &so->so_rcv;

                error = ENOTCONN;
                SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] (%d)\n",
                    __func__, proc_pid(p), (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so), error));
                /*
                 * This socket should have been disconnected and flushed
                 * prior to being returned from sodefunct(); there should
                 * be no data on its receive list, so panic otherwise.
                 */
                if (so->so_state & SS_DEFUNCT)
                        sb_empty_assert(sb, __func__);
                socket_unlock(so, 1);
                return (error);
        }

        if ((so->so_flags1 & SOF1_PRECONNECT_DATA) &&
            pr->pr_usrreqs->pru_preconnect) {
                /*
                 * A user may set the CONNECT_RESUME_ON_READ_WRITE-flag but not
                 * calling write() right after this. *If* the app calls a read
                 * we do not want to block this read indefinetely. Thus,
                 * we trigger a connect so that the session gets initiated.
                 */
                error = (*pr->pr_usrreqs->pru_preconnect)(so);

                if (error) {
                        socket_unlock(so, 1);
                        return (error);
                }
        }

        if (ENTR_SHOULDTRACE &&
            (SOCK_CHECK_DOM(so, AF_INET) || SOCK_CHECK_DOM(so, AF_INET6))) {
                /*
                 * enable energy tracing for inet sockets that go over
                 * non-loopback interfaces only.
                 */
                struct inpcb *inp = sotoinpcb(so);
                if (inp->inp_last_outifp != NULL &&
                    !(inp->inp_last_outifp->if_flags & IFF_LOOPBACK)) {
                        en_tracing = TRUE;
                        KERNEL_ENERGYTRACE(kEnTrActKernSockRead, DBG_FUNC_START,
                            VM_KERNEL_ADDRPERM(so),
                            ((so->so_state & SS_NBIO) ?
                            kEnTrFlagNonBlocking : 0),
                            (int64_t)orig_resid);
                }
        }

        /*
         * When SO_WANTOOBFLAG is set we try to get out-of-band data
         * regardless of the flags argument. Here is the case were
         * out-of-band data is not inline.
         */
        if ((flags & MSG_OOB) ||
            ((so->so_options & SO_WANTOOBFLAG) != 0 &&
            (so->so_options & SO_OOBINLINE) == 0 &&
            (so->so_oobmark || (so->so_state & SS_RCVATMARK)))) {
                m = m_get(M_WAIT, MT_DATA);
                if (m == NULL) {
                        socket_unlock(so, 1);
                        KERNEL_DEBUG(DBG_FNC_SORECEIVE | DBG_FUNC_END,
                            ENOBUFS, 0, 0, 0, 0);
                        return (ENOBUFS);
                }
                error = (*pr->pr_usrreqs->pru_rcvoob)(so, m, flags & MSG_PEEK);
                if (error)
                        goto bad;
                socket_unlock(so, 0);
                do {
                        error = uiomove(mtod(m, caddr_t),
                            imin(uio_resid(uio), m->m_len), uio);
                        m = m_free(m);
                } while (uio_resid(uio) && error == 0 && m != NULL);
                socket_lock(so, 0);
bad:
                if (m != NULL)
                        m_freem(m);

                if ((so->so_options & SO_WANTOOBFLAG) != 0) {
                        if (error == EWOULDBLOCK || error == EINVAL) {
                                /*
                                 * Let's try to get normal data:
                                 * EWOULDBLOCK: out-of-band data not
                                 * receive yet. EINVAL: out-of-band data
                                 * already read.
                                 */
                                error = 0;
                                goto nooob;
                        } else if (error == 0 && flagsp != NULL) {
                                *flagsp |= MSG_OOB;
                        }
                }
                socket_unlock(so, 1);
                if (en_tracing) {
                        KERNEL_ENERGYTRACE(kEnTrActKernSockRead, DBG_FUNC_END,
                            VM_KERNEL_ADDRPERM(so), 0,
                            (int64_t)(orig_resid - uio_resid(uio)));
                }
                KERNEL_DEBUG(DBG_FNC_SORECEIVE | DBG_FUNC_END, error,
                    0, 0, 0, 0);

                return (error);
        }
nooob:
        if (mp != NULL)
                *mp = NULL;

        if (so->so_state & SS_ISCONFIRMING && uio_resid(uio)) {
                (*pr->pr_usrreqs->pru_rcvd)(so, 0);
        }

        free_list = NULL;
        delayed_copy_len = 0;
restart:
#ifdef MORE_LOCKING_DEBUG
        if (so->so_usecount <= 1)
                printf("soreceive: sblock so=0x%llx ref=%d on socket\n",
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so), so->so_usecount);
#endif
        /*
         * See if the socket has been closed (SS_NOFDREF|SS_CANTRCVMORE)
         * and if so just return to the caller.  This could happen when
         * soreceive() is called by a socket upcall function during the
         * time the socket is freed.  The socket buffer would have been
         * locked across the upcall, therefore we cannot put this thread
         * to sleep (else we will deadlock) or return EWOULDBLOCK (else
         * we may livelock), because the lock on the socket buffer will
         * only be released when the upcall routine returns to its caller.
         * Because the socket has been officially closed, there can be
         * no further read on it.
         *
         * A multipath subflow socket would have its SS_NOFDREF set by
         * default, so check for SOF_MP_SUBFLOW socket flag; when the
         * socket is closed for real, SOF_MP_SUBFLOW would be cleared.
         */
        if ((so->so_state & (SS_NOFDREF | SS_CANTRCVMORE)) ==
            (SS_NOFDREF | SS_CANTRCVMORE) && !(so->so_flags & SOF_MP_SUBFLOW)) {
                socket_unlock(so, 1);
                return (0);
        }

        error = sblock(&so->so_rcv, SBLOCKWAIT(flags));
        if (error) {
                socket_unlock(so, 1);
                KERNEL_DEBUG(DBG_FNC_SORECEIVE | DBG_FUNC_END, error,
                    0, 0, 0, 0);
                if (en_tracing) {
                        KERNEL_ENERGYTRACE(kEnTrActKernSockRead, DBG_FUNC_END,
                            VM_KERNEL_ADDRPERM(so), 0,
                            (int64_t)(orig_resid - uio_resid(uio)));
                }
                return (error);
        }

        m = so->so_rcv.sb_mb;
        /*
         * If we have less data than requested, block awaiting more
         * (subject to any timeout) if:
         *   1. the current count is less than the low water mark, or
         *   2. MSG_WAITALL is set, and it is possible to do the entire
         *      receive operation at once if we block (resid <= hiwat).
         *   3. MSG_DONTWAIT is not set
         * If MSG_WAITALL is set but resid is larger than the receive buffer,
         * we have to do the receive in sections, and thus risk returning
         * a short count if a timeout or signal occurs after we start.
         */
        if (m == NULL || (((flags & MSG_DONTWAIT) == 0 &&
            so->so_rcv.sb_cc < uio_resid(uio)) &&
            (so->so_rcv.sb_cc < so->so_rcv.sb_lowat ||
            ((flags & MSG_WAITALL) && uio_resid(uio) <= so->so_rcv.sb_hiwat)) &&
            m->m_nextpkt == NULL && (pr->pr_flags & PR_ATOMIC) == 0)) {
                /*
                 * Panic if we notice inconsistencies in the socket's
                 * receive list; both sb_mb and sb_cc should correctly
                 * reflect the contents of the list, otherwise we may
                 * end up with false positives during select() or poll()
                 * which could put the application in a bad state.
                 */
                SB_MB_CHECK(&so->so_rcv);

                if (so->so_error) {
                        if (m != NULL)
                                goto dontblock;
                        error = so->so_error;
                        if ((flags & MSG_PEEK) == 0)
                                so->so_error = 0;
                        goto release;
                }
                if (so->so_state & SS_CANTRCVMORE) {
#if CONTENT_FILTER
                        /*
                         * Deal with half closed connections
                         */
                        if ((so->so_state & SS_ISDISCONNECTED) == 0 &&
                                cfil_sock_data_pending(&so->so_rcv) != 0)
                                CFIL_LOG(LOG_INFO,
                                        "so %llx ignore SS_CANTRCVMORE",
                                        (uint64_t)DEBUG_KERNEL_ADDRPERM(so));
                        else
#endif /* CONTENT_FILTER */
                        if (m != NULL)
                                goto dontblock;
                        else
                                goto release;
                }
                for (; m != NULL; m = m->m_next)
                        if (m->m_type == MT_OOBDATA || (m->m_flags & M_EOR)) {
                                m = so->so_rcv.sb_mb;
                                goto dontblock;
                        }
                if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) == 0 &&
                    (so->so_proto->pr_flags & PR_CONNREQUIRED)) {
                        error = ENOTCONN;
                        goto release;
                }
                if (uio_resid(uio) == 0)
                        goto release;

                if ((so->so_state & SS_NBIO) ||
                    (flags & (MSG_DONTWAIT|MSG_NBIO))) {
                        error = EWOULDBLOCK;
                        goto release;
                }
                SBLASTRECORDCHK(&so->so_rcv, "soreceive sbwait 1");
                SBLASTMBUFCHK(&so->so_rcv, "soreceive sbwait 1");
                sbunlock(&so->so_rcv, TRUE);    /* keep socket locked */
#if EVEN_MORE_LOCKING_DEBUG
                if (socket_debug)
                        printf("Waiting for socket data\n");
#endif

                error = sbwait(&so->so_rcv);
#if EVEN_MORE_LOCKING_DEBUG
                if (socket_debug)
                        printf("SORECEIVE - sbwait returned %d\n", error);
#endif
                if (so->so_usecount < 1) {
                        panic("%s: after 2nd sblock so=%p ref=%d on socket\n",
                            __func__, so, so->so_usecount);
                        /* NOTREACHED */
                }
                if (error) {
                        socket_unlock(so, 1);
                        KERNEL_DEBUG(DBG_FNC_SORECEIVE | DBG_FUNC_END, error,
                            0, 0, 0, 0);
                        if (en_tracing) {
                                KERNEL_ENERGYTRACE(kEnTrActKernSockRead, DBG_FUNC_END,
                                    VM_KERNEL_ADDRPERM(so), 0,
                                    (int64_t)(orig_resid - uio_resid(uio)));
                        }
                        return (error);
                }
                goto restart;
        }
dontblock:
        OSIncrementAtomicLong(&p->p_stats->p_ru.ru_msgrcv);
        SBLASTRECORDCHK(&so->so_rcv, "soreceive 1");
        SBLASTMBUFCHK(&so->so_rcv, "soreceive 1");
        nextrecord = m->m_nextpkt;

        if ((pr->pr_flags & PR_ADDR) && m->m_type == MT_SONAME) {
                error = soreceive_addr(p, so, psa, flags, &m, &nextrecord,
                    mp0 == NULL);
                if (error == ERESTART)
                        goto restart;
                else if (error != 0)
                        goto release;
                orig_resid = 0;
        }

        /*
         * Process one or more MT_CONTROL mbufs present before any data mbufs
         * in the first mbuf chain on the socket buffer.  If MSG_PEEK, we
         * just copy the data; if !MSG_PEEK, we call into the protocol to
         * perform externalization.
         */
        if (m != NULL && m->m_type == MT_CONTROL) {
                error = soreceive_ctl(so, controlp, flags, &m, &nextrecord);
                if (error != 0)
                        goto release;
                orig_resid = 0;
        }

        /*
         * If the socket is a TCP socket with message delivery
         * enabled, then create a control msg to deliver the
         * relative TCP sequence number for this data. Waiting
         * until this point will protect against failures to
         * allocate an mbuf for control msgs.
         */
        if (so->so_type == SOCK_STREAM && SOCK_PROTO(so) == IPPROTO_TCP &&
            (so->so_flags & SOF_ENABLE_MSGS) && controlp != NULL) {
                struct mbuf *seq_cm;

                seq_cm = sbcreatecontrol((caddr_t)&m->m_pkthdr.msg_seq,
                    sizeof (uint32_t), SCM_SEQNUM, SOL_SOCKET);
                if (seq_cm == NULL) {
                        /* unable to allocate a control mbuf */
                        error = ENOBUFS;
                        goto release;
                }
                *controlp = seq_cm;
                controlp = &seq_cm->m_next;
        }

        if (m != NULL) {
                if (!(flags & MSG_PEEK)) {
                        /*
                         * We get here because m points to an mbuf following
                         * any MT_SONAME or MT_CONTROL mbufs which have been
                         * processed above.  In any case, m should be pointing
                         * to the head of the mbuf chain, and the nextrecord
                         * should be either NULL or equal to m->m_nextpkt.
                         * See comments above about SB_LOCK.
                         */
                        if (m != so->so_rcv.sb_mb ||
                            m->m_nextpkt != nextrecord) {
                                panic("%s: post-control !sync so=%p m=%p "
                                    "nextrecord=%p\n", __func__, so, m,
                                    nextrecord);
                                /* NOTREACHED */
                        }
                        if (nextrecord == NULL)
                                so->so_rcv.sb_lastrecord = m;
                }
                type = m->m_type;
                if (type == MT_OOBDATA)
                        flags |= MSG_OOB;
        } else {
                if (!(flags & MSG_PEEK)) {
                        SB_EMPTY_FIXUP(&so->so_rcv);
                }
        }
        SBLASTRECORDCHK(&so->so_rcv, "soreceive 2");
        SBLASTMBUFCHK(&so->so_rcv, "soreceive 2");

        moff = 0;
        offset = 0;

        if (!(flags & MSG_PEEK) && uio_resid(uio) > sorecvmincopy)
                can_delay = 1;
        else
                can_delay = 0;

        need_event = 0;

        while (m != NULL &&
            (uio_resid(uio) - delayed_copy_len) > 0 && error == 0) {
                if (m->m_type == MT_OOBDATA) {
                        if (type != MT_OOBDATA)
                                break;
                } else if (type == MT_OOBDATA) {
                        break;
                }
                /*
                 * Make sure to allways set MSG_OOB event when getting
                 * out of band data inline.
                 */
                if ((so->so_options & SO_WANTOOBFLAG) != 0 &&
                    (so->so_options & SO_OOBINLINE) != 0 &&
                    (so->so_state & SS_RCVATMARK) != 0) {
                        flags |= MSG_OOB;
                }
                so->so_state &= ~SS_RCVATMARK;
                len = uio_resid(uio) - delayed_copy_len;
                if (so->so_oobmark && len > so->so_oobmark - offset)
                        len = so->so_oobmark - offset;
                if (len > m->m_len - moff)
                        len = m->m_len - moff;
                /*
                 * If mp is set, just pass back the mbufs.
                 * Otherwise copy them out via the uio, then free.
                 * Sockbuf must be consistent here (points to current mbuf,
                 * it points to next record) when we drop priority;
                 * we must note any additions to the sockbuf when we
                 * block interrupts again.
                 */
                if (mp == NULL) {
                        SBLASTRECORDCHK(&so->so_rcv, "soreceive uiomove");
                        SBLASTMBUFCHK(&so->so_rcv, "soreceive uiomove");
                        if (can_delay && len == m->m_len) {
                                /*
                                 * only delay the copy if we're consuming the
                                 * mbuf and we're NOT in MSG_PEEK mode
                                 * and we have enough data to make it worthwile
                                 * to drop and retake the lock... can_delay
                                 * reflects the state of the 2 latter
                                 * constraints moff should always be zero
                                 * in these cases
                                 */
                                delayed_copy_len += len;
                        } else {
                                if (delayed_copy_len) {
                                        error = sodelayed_copy(so, uio,
                                            &free_list, &delayed_copy_len);

                                        if (error) {
                                                goto release;
                                        }
                                        /*
                                         * can only get here if MSG_PEEK is not
                                         * set therefore, m should point at the
                                         * head of the rcv queue; if it doesn't,
                                         * it means something drastically
                                         * changed while we were out from behind
                                         * the lock in sodelayed_copy. perhaps
                                         * a RST on the stream. in any event,
                                         * the stream has been interrupted. it's
                                         * probably best just to return whatever
                                         * data we've moved and let the caller
                                         * sort it out...
                                         */
                                        if (m != so->so_rcv.sb_mb) {
                                                break;
                                        }
                                }
                                socket_unlock(so, 0);
                                error = uiomove(mtod(m, caddr_t) + moff,
                                    (int)len, uio);
                                socket_lock(so, 0);

                                if (error)
                                        goto release;
                        }
                } else {
                        uio_setresid(uio, (uio_resid(uio) - len));
                }
                if (len == m->m_len - moff) {
                        if (m->m_flags & M_EOR)
                                flags |= MSG_EOR;
                        if (flags & MSG_PEEK) {
                                m = m->m_next;
                                moff = 0;
                        } else {
                                nextrecord = m->m_nextpkt;
                                sbfree(&so->so_rcv, m);
                                m->m_nextpkt = NULL;

                                /*
                                 * If this packet is an unordered packet
                                 * (indicated by M_UNORDERED_DATA flag), remove
                                 * the additional bytes added to the
                                 * receive socket buffer size.
                                 */
                                if ((so->so_flags & SOF_ENABLE_MSGS) &&
                                    m->m_len &&
                                    (m->m_flags & M_UNORDERED_DATA) &&
                                    sbreserve(&so->so_rcv,
                                    so->so_rcv.sb_hiwat - m->m_len)) {
                                        if (so->so_msg_state->msg_uno_bytes >
                                            m->m_len) {
                                                so->so_msg_state->
                                                    msg_uno_bytes -= m->m_len;
                                        } else {
                                                so->so_msg_state->
                                                    msg_uno_bytes = 0;
                                        }
                                        m->m_flags &= ~M_UNORDERED_DATA;
                                }

                                if (mp != NULL) {
                                        *mp = m;
                                        mp = &m->m_next;
                                        so->so_rcv.sb_mb = m = m->m_next;
                                        *mp = NULL;
                                } else {
                                        if (free_list == NULL)
                                                free_list = m;
                                        else
                                                ml->m_next = m;
                                        ml = m;
                                        so->so_rcv.sb_mb = m = m->m_next;
                                        ml->m_next = NULL;
                                }
                                if (m != NULL) {
                                        m->m_nextpkt = nextrecord;
                                        if (nextrecord == NULL)
                                                so->so_rcv.sb_lastrecord = m;
                                } else {
                                        so->so_rcv.sb_mb = nextrecord;
                                        SB_EMPTY_FIXUP(&so->so_rcv);
                                }
                                SBLASTRECORDCHK(&so->so_rcv, "soreceive 3");
                                SBLASTMBUFCHK(&so->so_rcv, "soreceive 3");
                        }
                } else {
                        if (flags & MSG_PEEK) {
                                moff += len;
                        } else {
                                if (mp != NULL) {
                                        int copy_flag;

                                        if (flags & MSG_DONTWAIT)
                                                copy_flag = M_DONTWAIT;
                                        else
                                                copy_flag = M_WAIT;
                                        *mp = m_copym(m, 0, len, copy_flag);
                                        /*
                                         * Failed to allocate an mbuf?
                                         * Adjust uio_resid back, it was
                                         * adjusted down by len bytes which
                                         * we didn't copy over.
                                         */
                                        if (*mp == NULL) {
                                                uio_setresid(uio,
                                                    (uio_resid(uio) + len));
                                                break;
                                        }
                                }
                                m->m_data += len;
                                m->m_len -= len;
                                so->so_rcv.sb_cc -= len;
                        }
                }
                if (so->so_oobmark) {
                        if ((flags & MSG_PEEK) == 0) {
                                so->so_oobmark -= len;
                                if (so->so_oobmark == 0) {
                                        so->so_state |= SS_RCVATMARK;
                                        /*
                                         * delay posting the actual event until
                                         * after any delayed copy processing
                                         * has finished
                                         */
                                        need_event = 1;
                                        break;
                                }
                        } else {
                                offset += len;
                                if (offset == so->so_oobmark)
                                        break;
                        }
                }
                if (flags & MSG_EOR)
                        break;
                /*
                 * If the MSG_WAITALL or MSG_WAITSTREAM flag is set
                 * (for non-atomic socket), we must not quit until
                 * "uio->uio_resid == 0" or an error termination.
                 * If a signal/timeout occurs, return with a short
                 * count but without error.  Keep sockbuf locked
                 * against other readers.
                 */
                while (flags & (MSG_WAITALL|MSG_WAITSTREAM) && m == NULL &&
                    (uio_resid(uio) - delayed_copy_len) > 0 &&
                    !sosendallatonce(so) && !nextrecord) {
                        if (so->so_error || ((so->so_state & SS_CANTRCVMORE)
#if CONTENT_FILTER
                            && cfil_sock_data_pending(&so->so_rcv) == 0
#endif /* CONTENT_FILTER */
                            ))
                                goto release;

                        /*
                         * Depending on the protocol (e.g. TCP), the following
                         * might cause the socket lock to be dropped and later
                         * be reacquired, and more data could have arrived and
                         * have been appended to the receive socket buffer by
                         * the time it returns.  Therefore, we only sleep in
                         * sbwait() below if and only if the socket buffer is
                         * empty, in order to avoid a false sleep.
                         */
                        if (pr->pr_flags & PR_WANTRCVD && so->so_pcb &&
                            (((struct inpcb *)so->so_pcb)->inp_state !=
                            INPCB_STATE_DEAD))
                                (*pr->pr_usrreqs->pru_rcvd)(so, flags);

                        SBLASTRECORDCHK(&so->so_rcv, "soreceive sbwait 2");
                        SBLASTMBUFCHK(&so->so_rcv, "soreceive sbwait 2");

                        if (so->so_rcv.sb_mb == NULL && sbwait(&so->so_rcv)) {
                                error = 0;
                                goto release;
                        }
                        /*
                         * have to wait until after we get back from the sbwait
                         * to do the copy because we will drop the lock if we
                         * have enough data that has been delayed... by dropping
                         * the lock we open up a window allowing the netisr
                         * thread to process the incoming packets and to change
                         * the state of this socket... we're issuing the sbwait
                         * because the socket is empty and we're expecting the
                         * netisr thread to wake us up when more packets arrive;
                         * if we allow that processing to happen and then sbwait
                         * we could stall forever with packets sitting in the
                         * socket if no further packets arrive from the remote
                         * side.
                         *
                         * we want to copy before we've collected all the data
                         * to satisfy this request to allow the copy to overlap
                         * the incoming packet processing on an MP system
                         */
                        if (delayed_copy_len > sorecvmincopy &&
                            (delayed_copy_len > (so->so_rcv.sb_hiwat / 2))) {
                                error = sodelayed_copy(so, uio,
                                    &free_list, &delayed_copy_len);

                                if (error)
                                        goto release;
                        }
                        m = so->so_rcv.sb_mb;
                        if (m != NULL) {
                                nextrecord = m->m_nextpkt;
                        }
                        SB_MB_CHECK(&so->so_rcv);
                }
        }
#ifdef MORE_LOCKING_DEBUG
        if (so->so_usecount <= 1) {
                panic("%s: after big while so=%p ref=%d on socket\n",
                    __func__, so, so->so_usecount);
                /* NOTREACHED */
        }
#endif

        if (m != NULL && pr->pr_flags & PR_ATOMIC) {
                if (so->so_options & SO_DONTTRUNC) {
                        flags |= MSG_RCVMORE;
                } else {
                        flags |= MSG_TRUNC;
                        if ((flags & MSG_PEEK) == 0)
                                (void) sbdroprecord(&so->so_rcv);
                }
        }

        /*
         * pru_rcvd below (for TCP) may cause more data to be received
         * if the socket lock is dropped prior to sending the ACK; some
         * legacy OpenTransport applications don't handle this well
         * (if it receives less data than requested while MSG_HAVEMORE
         * is set), and so we set the flag now based on what we know
         * prior to calling pru_rcvd.
         */
        if ((so->so_options & SO_WANTMORE) && so->so_rcv.sb_cc > 0)
                flags |= MSG_HAVEMORE;

        if ((flags & MSG_PEEK) == 0) {
                if (m == NULL) {
                        so->so_rcv.sb_mb = nextrecord;
                        /*
                         * First part is an inline SB_EMPTY_FIXUP().  Second
                         * part makes sure sb_lastrecord is up-to-date if
                         * there is still data in the socket buffer.
                         */
                        if (so->so_rcv.sb_mb == NULL) {
                                so->so_rcv.sb_mbtail = NULL;
                                so->so_rcv.sb_lastrecord = NULL;
                        } else if (nextrecord->m_nextpkt == NULL) {
                                so->so_rcv.sb_lastrecord = nextrecord;
                        }
                        SB_MB_CHECK(&so->so_rcv);
                }
                SBLASTRECORDCHK(&so->so_rcv, "soreceive 4");
                SBLASTMBUFCHK(&so->so_rcv, "soreceive 4");
                if (pr->pr_flags & PR_WANTRCVD && so->so_pcb)
                        (*pr->pr_usrreqs->pru_rcvd)(so, flags);
        }

        if (delayed_copy_len) {
                error = sodelayed_copy(so, uio, &free_list, &delayed_copy_len);
                if (error)
                        goto release;
        }
        if (free_list != NULL) {
                m_freem_list(free_list);
                free_list = NULL;
        }
        if (need_event)
                postevent(so, 0, EV_OOB);

        if (orig_resid == uio_resid(uio) && orig_resid &&
            (flags & MSG_EOR) == 0 && (so->so_state & SS_CANTRCVMORE) == 0) {
                sbunlock(&so->so_rcv, TRUE);    /* keep socket locked */
                goto restart;
        }

        if (flagsp != NULL)
                *flagsp |= flags;
release:
#ifdef MORE_LOCKING_DEBUG
        if (so->so_usecount <= 1) {
                panic("%s: release so=%p ref=%d on socket\n", __func__,
                    so, so->so_usecount);
                /* NOTREACHED */
        }
#endif
        if (delayed_copy_len)
                error = sodelayed_copy(so, uio, &free_list, &delayed_copy_len);

        if (free_list != NULL)
                m_freem_list(free_list);

        sbunlock(&so->so_rcv, FALSE);   /* will unlock socket */

        if (en_tracing) {
                KERNEL_ENERGYTRACE(kEnTrActKernSockRead, DBG_FUNC_END,
                    VM_KERNEL_ADDRPERM(so),
                    ((error == EWOULDBLOCK) ? kEnTrFlagNoWork : 0),
                    (int64_t)(orig_resid - uio_resid(uio)));
        }
        KERNEL_DEBUG(DBG_FNC_SORECEIVE | DBG_FUNC_END, so, uio_resid(uio),
            so->so_rcv.sb_cc, 0, error);

        return (error);
}

/*
 * Returns:     0                       Success
 *      uiomove:EFAULT
 */
static int
sodelayed_copy(struct socket *so, struct uio *uio, struct mbuf **free_list,
    user_ssize_t *resid)
{
        int error = 0;
        struct mbuf *m;

        m = *free_list;

        socket_unlock(so, 0);

        while (m != NULL && error == 0) {
                error = uiomove(mtod(m, caddr_t), (int)m->m_len, uio);
                m = m->m_next;
        }
        m_freem_list(*free_list);

        *free_list = NULL;
        *resid = 0;

        socket_lock(so, 0);

        return (error);
}

static int
sodelayed_copy_list(struct socket *so, struct recv_msg_elem *msgarray,
    u_int uiocnt, struct mbuf **free_list, user_ssize_t *resid)
{
#pragma unused(so)
        int error = 0;
        struct mbuf *ml, *m;
        int i = 0;
        struct uio *auio;

        for (ml = *free_list, i = 0; ml != NULL && i < uiocnt;
            ml = ml->m_nextpkt, i++) {
                auio = msgarray[i].uio;
                for (m = ml; m != NULL; m = m->m_next) {
                        error = uiomove(mtod(m, caddr_t), m->m_len, auio);
                        if (error != 0)
                                goto out;
                }
        }
out:
        m_freem_list(*free_list);

        *free_list = NULL;
        *resid = 0;

        return (error);
}

int
soreceive_list(struct socket *so, struct recv_msg_elem *msgarray, u_int uiocnt,
    int *flagsp)
{
        struct mbuf *m;
        struct mbuf *nextrecord;
        struct mbuf *ml = NULL, *free_list = NULL, *free_tail = NULL;
        int error;
        user_ssize_t len, pktlen, delayed_copy_len = 0;
        struct protosw *pr = so->so_proto;
        user_ssize_t resid;
        struct proc *p = current_proc();
        struct uio *auio = NULL;
        int npkts = 0;
        int sblocked = 0;
        struct sockaddr **psa = NULL;
        struct mbuf **controlp = NULL;
        int can_delay;
        int flags;
        struct mbuf *free_others = NULL;

        KERNEL_DEBUG(DBG_FNC_SORECEIVE_LIST | DBG_FUNC_START,
            so, uiocnt,
            so->so_rcv.sb_cc, so->so_rcv.sb_lowat, so->so_rcv.sb_hiwat);

        /*
         * Sanity checks:
         * - Only supports don't wait flags
         * - Only support datagram sockets (could be extended to raw)
         * - Must be atomic
         * - Protocol must support packet chains
         * - The uio array is NULL (should we panic?)
         */
        if (flagsp != NULL)
                flags = *flagsp;
        else
                flags = 0;
        if (flags & ~(MSG_PEEK | MSG_WAITALL | MSG_DONTWAIT | MSG_NEEDSA |
            MSG_NBIO)) {
                printf("%s invalid flags 0x%x\n", __func__, flags);
                error = EINVAL;
                goto out;
        }
        if (so->so_type != SOCK_DGRAM) {
                error = EINVAL;
                goto out;
        }
        if (sosendallatonce(so) == 0) {
                error = EINVAL;
                goto out;
        }
        if (so->so_proto->pr_usrreqs->pru_send_list == NULL) {
                error = EPROTONOSUPPORT;
                goto out;
        }
        if (msgarray == NULL) {
                printf("%s uioarray is NULL\n", __func__);
                error = EINVAL;
                goto out;
        }
        if (uiocnt == 0) {
                printf("%s uiocnt is 0\n", __func__);
                error = EINVAL;
                goto out;
        }
        /*
         * Sanity check on the length passed by caller as we are making 'int'
         * comparisons
         */
        resid = recv_msg_array_resid(msgarray, uiocnt);
        if (resid < 0 || resid > INT_MAX) {
                error = EINVAL;
                goto out;
        }

        if (!(flags & MSG_PEEK) && sorecvmincopy > 0)
                can_delay = 1;
        else
                can_delay = 0;

        socket_lock(so, 1);
        so_update_last_owner_locked(so, p);
        so_update_policy(so);

#if NECP
        so_update_necp_policy(so, NULL, NULL);
#endif /* NECP */

        /*
         * If a recv attempt is made on a previously-accepted socket
         * that has been marked as inactive (disconnected), reject
         * the request.
         */
        if (so->so_flags & SOF_DEFUNCT) {
                struct sockbuf *sb = &so->so_rcv;

                error = ENOTCONN;
                SODEFUNCTLOG(("%s[%d]: defunct so 0x%llx [%d,%d] (%d)\n",
                    __func__, proc_pid(p), (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so), error));
                /*
                 * This socket should have been disconnected and flushed
                 * prior to being returned from sodefunct(); there should
                 * be no data on its receive list, so panic otherwise.
                 */
                if (so->so_state & SS_DEFUNCT)
                        sb_empty_assert(sb, __func__);
                goto release;
        }

next:
        /*
         * The uio may be empty
         */
        if (npkts >= uiocnt) {
                error = 0;
                goto release;
        }
restart:
        /*
         * See if the socket has been closed (SS_NOFDREF|SS_CANTRCVMORE)
         * and if so just return to the caller.  This could happen when
         * soreceive() is called by a socket upcall function during the
         * time the socket is freed.  The socket buffer would have been
         * locked across the upcall, therefore we cannot put this thread
         * to sleep (else we will deadlock) or return EWOULDBLOCK (else
         * we may livelock), because the lock on the socket buffer will
         * only be released when the upcall routine returns to its caller.
         * Because the socket has been officially closed, there can be
         * no further read on it.
         */
        if ((so->so_state & (SS_NOFDREF | SS_CANTRCVMORE)) ==
            (SS_NOFDREF | SS_CANTRCVMORE)) {
                error = 0;
                goto release;
        }

        error = sblock(&so->so_rcv, SBLOCKWAIT(flags));
        if (error) {
                goto release;
        }
        sblocked = 1;

        m = so->so_rcv.sb_mb;
        /*
         * Block awaiting more datagram if needed
         */
        if (m == NULL || (((flags & MSG_DONTWAIT) == 0 &&
            (so->so_rcv.sb_cc < so->so_rcv.sb_lowat ||
            ((flags & MSG_WAITALL) && npkts < uiocnt))))) {
                /*
                 * Panic if we notice inconsistencies in the socket's
                 * receive list; both sb_mb and sb_cc should correctly
                 * reflect the contents of the list, otherwise we may
                 * end up with false positives during select() or poll()
                 * which could put the application in a bad state.
                 */
                SB_MB_CHECK(&so->so_rcv);

                if (so->so_error) {
                        error = so->so_error;
                        if ((flags & MSG_PEEK) == 0)
                                so->so_error = 0;
                        goto release;
                }
                if (so->so_state & SS_CANTRCVMORE) {
                        goto release;
                }
                if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) == 0 &&
                    (so->so_proto->pr_flags & PR_CONNREQUIRED)) {
                        error = ENOTCONN;
                        goto release;
                }
                if ((so->so_state & SS_NBIO) ||
                    (flags & (MSG_DONTWAIT|MSG_NBIO))) {
                        error = EWOULDBLOCK;
                        goto release;
                }
                /*
                 * Do not block if we got some data
                 */
                if (free_list != NULL) {
                        error = 0;
                        goto release;
                }

                SBLASTRECORDCHK(&so->so_rcv, "soreceive sbwait 1");
                SBLASTMBUFCHK(&so->so_rcv, "soreceive sbwait 1");

                sbunlock(&so->so_rcv, TRUE);    /* keep socket locked */
                sblocked = 0;

                error = sbwait(&so->so_rcv);
                if (error) {
                        goto release;
                }
                goto restart;
        }

        OSIncrementAtomicLong(&p->p_stats->p_ru.ru_msgrcv);
        SBLASTRECORDCHK(&so->so_rcv, "soreceive 1");
        SBLASTMBUFCHK(&so->so_rcv, "soreceive 1");

        /*
         * Consume the current uio index as we have a datagram
         */
        auio = msgarray[npkts].uio;
        resid = uio_resid(auio);
        msgarray[npkts].which |= SOCK_MSG_DATA;
        psa = (msgarray[npkts].which & SOCK_MSG_SA) ?
            &msgarray[npkts].psa : NULL;
        controlp = (msgarray[npkts].which & SOCK_MSG_CONTROL) ?
            &msgarray[npkts].controlp : NULL;
        npkts += 1;
        nextrecord = m->m_nextpkt;

        if ((pr->pr_flags & PR_ADDR) && m->m_type == MT_SONAME) {
                error = soreceive_addr(p, so, psa, flags, &m, &nextrecord, 1);
                if (error == ERESTART)
                        goto restart;
                else if (error != 0)
                        goto release;
        }

        if (m != NULL && m->m_type == MT_CONTROL) {
                error = soreceive_ctl(so, controlp, flags, &m, &nextrecord);
                if (error != 0)
                        goto release;
        }

        if (m->m_pkthdr.len == 0) {
                printf("%s:%d so %llx pkt %llx type %u pktlen null\n",
                    __func__, __LINE__,
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(m),
                    m->m_type);
        }

        /*
         * Loop to copy the mbufs of the current record
         * Support zero length packets
         */
        ml = NULL;
        pktlen = 0;
        while (m != NULL && (len = resid - pktlen) >= 0 && error == 0) {
                if (m->m_len == 0)
                        panic("%p m_len zero", m);
                if (m->m_type == 0)
                        panic("%p m_type zero", m);
                /*
                 * Clip to the residual length
                 */
                if (len > m->m_len)
                        len = m->m_len;
                pktlen += len;
                /*
                 * Copy the mbufs via the uio or delay the copy
                 * Sockbuf must be consistent here (points to current mbuf,
                 * it points to next record) when we drop priority;
                 * we must note any additions to the sockbuf when we
                 * block interrupts again.
                 */
                if (len > 0 && can_delay == 0) {
                        socket_unlock(so, 0);
                        error = uiomove(mtod(m, caddr_t), (int)len, auio);
                        socket_lock(so, 0);
                        if (error)
                                goto release;
                } else {
                        delayed_copy_len += len;
                }

                if (len == m->m_len) {
                        /*
                         * m was entirely copied
                         */
                        sbfree(&so->so_rcv, m);
                        nextrecord = m->m_nextpkt;
                        m->m_nextpkt = NULL;

                        /*
                         * Set the first packet to the head of the free list
                         */
                        if (free_list == NULL)
                                free_list = m;
                        /*
                         * Link current packet to tail of free list
                         */
                        if (ml == NULL) {
                                if (free_tail != NULL)
                                        free_tail->m_nextpkt = m;
                                free_tail = m;
                        }
                        /*
                         * Link current mbuf to last mbuf of current packet
                         */
                        if (ml != NULL)
                                ml->m_next = m;
                        ml = m;

                        /*
                         * Move next buf to head of socket buffer
                         */
                        so->so_rcv.sb_mb = m = ml->m_next;
                        ml->m_next = NULL;

                        if (m != NULL) {
                                m->m_nextpkt = nextrecord;
                                if (nextrecord == NULL)
                                        so->so_rcv.sb_lastrecord = m;
                        } else {
                                so->so_rcv.sb_mb = nextrecord;
                                SB_EMPTY_FIXUP(&so->so_rcv);
                        }
                        SBLASTRECORDCHK(&so->so_rcv, "soreceive 3");
                        SBLASTMBUFCHK(&so->so_rcv, "soreceive 3");
                } else {
                        /*
                         * Stop the loop on partial copy
                         */
                        break;
                }
        }
#ifdef MORE_LOCKING_DEBUG
        if (so->so_usecount <= 1) {
                panic("%s: after big while so=%llx ref=%d on socket\n",
                    __func__,
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so), so->so_usecount);
                /* NOTREACHED */
        }
#endif
        /*
         * Tell the caller we made a partial copy
         */
        if (m != NULL) {
                if (so->so_options & SO_DONTTRUNC) {
                        /*
                         * Copyout first the freelist then the partial mbuf
                         */
                        socket_unlock(so, 0);
                        if (delayed_copy_len)
                                error = sodelayed_copy_list(so, msgarray,
                                    uiocnt, &free_list, &delayed_copy_len);

                        if (error == 0) {
                                error = uiomove(mtod(m, caddr_t), (int)len,
                                    auio);
                        }
                        socket_lock(so, 0);
                        if (error)
                                goto release;

                        m->m_data += len;
                        m->m_len -= len;
                        so->so_rcv.sb_cc -= len;
                        flags |= MSG_RCVMORE;
                } else {
                        (void) sbdroprecord(&so->so_rcv);
                        nextrecord = so->so_rcv.sb_mb;
                        m = NULL;
                        flags |= MSG_TRUNC;
                }
        }

        if (m == NULL) {
                so->so_rcv.sb_mb = nextrecord;
                /*
                 * First part is an inline SB_EMPTY_FIXUP().  Second
                 * part makes sure sb_lastrecord is up-to-date if
                 * there is still data in the socket buffer.
                 */
                if (so->so_rcv.sb_mb == NULL) {
                        so->so_rcv.sb_mbtail = NULL;
                        so->so_rcv.sb_lastrecord = NULL;
                } else if (nextrecord->m_nextpkt == NULL) {
                        so->so_rcv.sb_lastrecord = nextrecord;
                }
                SB_MB_CHECK(&so->so_rcv);
        }
        SBLASTRECORDCHK(&so->so_rcv, "soreceive 4");
        SBLASTMBUFCHK(&so->so_rcv, "soreceive 4");

        /*
         * We can continue to the next packet as long as:
         * - We haven't exhausted the uio array
         * - There was no error
         * - A packet was not truncated
         * - We can still receive more data
         */
        if (npkts < uiocnt && error == 0 &&
            (flags & (MSG_RCVMORE | MSG_TRUNC)) == 0 &&
            (so->so_state & SS_CANTRCVMORE) == 0) {
                sbunlock(&so->so_rcv, TRUE);    /* keep socket locked */
                sblocked = 0;

                goto next;
        }
        if (flagsp != NULL)
                *flagsp |= flags;

release:
        /*
         * pru_rcvd may cause more data to be received if the socket lock
         * is dropped so we set MSG_HAVEMORE now based on what we know.
         * That way the caller won't be surprised if it receives less data
         * than requested.
         */
        if ((so->so_options & SO_WANTMORE) && so->so_rcv.sb_cc > 0)
                flags |= MSG_HAVEMORE;

        if (pr->pr_flags & PR_WANTRCVD && so->so_pcb)
                (*pr->pr_usrreqs->pru_rcvd)(so, flags);

        if (sblocked)
                sbunlock(&so->so_rcv, FALSE);   /* will unlock socket */
        else
                socket_unlock(so, 1);

        if (delayed_copy_len)
                error = sodelayed_copy_list(so, msgarray, uiocnt,
                    &free_list, &delayed_copy_len);
out:
        /*
         * Amortize the cost of freeing the mbufs
         */
        if (free_list != NULL)
                m_freem_list(free_list);
        if (free_others != NULL)
                m_freem_list(free_others);

        KERNEL_DEBUG(DBG_FNC_SORECEIVE_LIST | DBG_FUNC_END, error,
            0, 0, 0, 0);
        return (error);
}

/*
 * Returns:     0                       Success
 *              EINVAL
 *              ENOTCONN
 *      <pru_shutdown>:EINVAL
 *      <pru_shutdown>:EADDRNOTAVAIL[TCP]
 *      <pru_shutdown>:ENOBUFS[TCP]
 *      <pru_shutdown>:EMSGSIZE[TCP]
 *      <pru_shutdown>:EHOSTUNREACH[TCP]
 *      <pru_shutdown>:ENETUNREACH[TCP]
 *      <pru_shutdown>:ENETDOWN[TCP]
 *      <pru_shutdown>:ENOMEM[TCP]
 *      <pru_shutdown>:EACCES[TCP]
 *      <pru_shutdown>:EMSGSIZE[TCP]
 *      <pru_shutdown>:ENOBUFS[TCP]
 *      <pru_shutdown>:???[TCP]         [ignorable: mostly IPSEC/firewall/DLIL]
 *      <pru_shutdown>:???              [other protocol families]
 */
int
soshutdown(struct socket *so, int how)
{
        int error;

        KERNEL_DEBUG(DBG_FNC_SOSHUTDOWN | DBG_FUNC_START, how, 0, 0, 0, 0);

        switch (how) {
        case SHUT_RD:
        case SHUT_WR:
        case SHUT_RDWR:
                socket_lock(so, 1);
                if ((so->so_state &
                    (SS_ISCONNECTED|SS_ISCONNECTING|SS_ISDISCONNECTING)) == 0) {
                        error = ENOTCONN;
                } else {
                        error = soshutdownlock(so, how);
                }
                socket_unlock(so, 1);
                break;
        default:
                error = EINVAL;
                break;
        }

        KERNEL_DEBUG(DBG_FNC_SOSHUTDOWN | DBG_FUNC_END, how, error, 0, 0, 0);

        return (error);
}

int
soshutdownlock_final(struct socket *so, int how)
{
        struct protosw *pr = so->so_proto;
        int error = 0;

        sflt_notify(so, sock_evt_shutdown, &how);

        if (how != SHUT_WR) {
                if ((so->so_state & SS_CANTRCVMORE) != 0) {
                        /* read already shut down */
                        error = ENOTCONN;
                        goto done;
                }
                sorflush(so);
                postevent(so, 0, EV_RCLOSED);
        }
        if (how != SHUT_RD) {
                if ((so->so_state & SS_CANTSENDMORE) != 0) {
                        /* write already shut down */
                        error = ENOTCONN;
                        goto done;
                }
                error = (*pr->pr_usrreqs->pru_shutdown)(so);
                postevent(so, 0, EV_WCLOSED);
        }
done:
        KERNEL_DEBUG(DBG_FNC_SOSHUTDOWN, how, 1, 0, 0, 0);
        return (error);
}

int
soshutdownlock(struct socket *so, int how)
{
        int error = 0;

#if CONTENT_FILTER
        /*
         * A content filter may delay the actual shutdown until it
         * has processed the pending data
         */
        if (so->so_flags & SOF_CONTENT_FILTER) {
                error = cfil_sock_shutdown(so, &how);
                if (error == EJUSTRETURN) {
                        error = 0;
                        goto done;
                } else if (error != 0) {
                        goto done;
                }
        }
#endif /* CONTENT_FILTER */

        error = soshutdownlock_final(so, how);

done:
        return (error);
}

void
sowflush(struct socket *so)
{
        struct sockbuf *sb = &so->so_snd;
#ifdef notyet
        lck_mtx_t *mutex_held;
        /*
         * 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 /* notyet */

        /*
         * 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);

        sb->sb_flags            &= ~(SB_SEL|SB_UPCALL);
        sb->sb_flags            |= SB_DROP;
        sb->sb_upcall           = NULL;
        sb->sb_upcallarg        = NULL;

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

        selthreadclear(&sb->sb_sel);
        sbrelease(sb);
}

void
sorflush(struct socket *so)
{
        struct sockbuf *sb = &so->so_rcv;
        struct protosw *pr = so->so_proto;
        struct sockbuf asb;
#ifdef notyet
        lck_mtx_t *mutex_held;
        /*
         * 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 /* notyet */

        sflt_notify(so, sock_evt_flush_read, NULL);

        socantrcvmore(so);

        /*
         * 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);

        /*
         * Copy only the relevant fields from "sb" to "asb" which we
         * need for sbrelease() to function.  In particular, skip
         * sb_sel as it contains the wait queue linkage, which would
         * wreak havoc if we were to issue selthreadclear() on "asb".
         * Make sure to not carry over SB_LOCK in "asb", as we need
         * to acquire it later as part of sbrelease().
         */
        bzero(&asb, sizeof (asb));
        asb.sb_cc               = sb->sb_cc;
        asb.sb_hiwat            = sb->sb_hiwat;
        asb.sb_mbcnt            = sb->sb_mbcnt;
        asb.sb_mbmax            = sb->sb_mbmax;
        asb.sb_ctl              = sb->sb_ctl;
        asb.sb_lowat            = sb->sb_lowat;
        asb.sb_mb               = sb->sb_mb;
        asb.sb_mbtail           = sb->sb_mbtail;
        asb.sb_lastrecord       = sb->sb_lastrecord;
        asb.sb_so               = sb->sb_so;
        asb.sb_flags            = sb->sb_flags;
        asb.sb_flags            &= ~(SB_LOCK|SB_SEL|SB_KNOTE|SB_UPCALL);
        asb.sb_flags            |= SB_DROP;

        /*
         * Ideally we'd bzero() these and preserve the ones we need;
         * but to do that we'd need to shuffle things around in the
         * sockbuf, and we can't do it now because there are KEXTS
         * that are directly referring to the socket structure.
         *
         * Setting SB_DROP acts as a barrier to prevent further appends.
         * Clearing SB_SEL is done for selthreadclear() below.
         */
        sb->sb_cc               = 0;
        sb->sb_hiwat            = 0;
        sb->sb_mbcnt            = 0;
        sb->sb_mbmax            = 0;
        sb->sb_ctl              = 0;
        sb->sb_lowat            = 0;
        sb->sb_mb               = NULL;
        sb->sb_mbtail           = NULL;
        sb->sb_lastrecord       = NULL;
        sb->sb_timeo.tv_sec     = 0;
        sb->sb_timeo.tv_usec    = 0;
        sb->sb_upcall           = NULL;
        sb->sb_upcallarg        = NULL;
        sb->sb_flags            &= ~(SB_SEL|SB_UPCALL);
        sb->sb_flags            |= SB_DROP;

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

        /*
         * Note that selthreadclear() is called on the original "sb" and
         * not the local "asb" because of the way wait queue linkage is
         * implemented.  Given that selwakeup() may be triggered, SB_SEL
         * should no longer be set (cleared above.)
         */
        selthreadclear(&sb->sb_sel);

        if ((pr->pr_flags & PR_RIGHTS) && pr->pr_domain->dom_dispose)
                (*pr->pr_domain->dom_dispose)(asb.sb_mb);

        sbrelease(&asb);
}

/*
 * Perhaps this routine, and sooptcopyout(), below, ought to come in
 * an additional variant to handle the case where the option value needs
 * to be some kind of integer, but not a specific size.
 * In addition to their use here, these functions are also called by the
 * protocol-level pr_ctloutput() routines.
 *
 * Returns:     0                       Success
 *              EINVAL
 *      copyin:EFAULT
 */
int
sooptcopyin(struct sockopt *sopt, void *buf, size_t len, size_t minlen)
{
        size_t  valsize;

        /*
         * If the user gives us more than we wanted, we ignore it,
         * but if we don't get the minimum length the caller
         * wants, we return EINVAL.  On success, sopt->sopt_valsize
         * is set to however much we actually retrieved.
         */
        if ((valsize = sopt->sopt_valsize) < minlen)
                return (EINVAL);
        if (valsize > len)
                sopt->sopt_valsize = valsize = len;

        if (sopt->sopt_p != kernproc)
                return (copyin(sopt->sopt_val, buf, valsize));

        bcopy(CAST_DOWN(caddr_t, sopt->sopt_val), buf, valsize);
        return (0);
}

/*
 * sooptcopyin_timeval
 *   Copy in a timeval value into tv_p, and take into account whether the
 *   the calling process is 64-bit or 32-bit.  Moved the sanity checking
 *   code here so that we can verify the 64-bit tv_sec value before we lose
 *   the top 32-bits assigning tv64.tv_sec to tv_p->tv_sec.
 */
static int
sooptcopyin_timeval(struct sockopt *sopt, struct timeval *tv_p)
{
        int                     error;

        if (proc_is64bit(sopt->sopt_p)) {
                struct user64_timeval   tv64;

                if (sopt->sopt_valsize < sizeof (tv64))
                        return (EINVAL);

                sopt->sopt_valsize = sizeof (tv64);
                if (sopt->sopt_p != kernproc) {
                        error = copyin(sopt->sopt_val, &tv64, sizeof (tv64));
                        if (error != 0)
                                return (error);
                } else {
                        bcopy(CAST_DOWN(caddr_t, sopt->sopt_val), &tv64,
                            sizeof (tv64));
                }
                if (tv64.tv_sec < 0 || tv64.tv_sec > LONG_MAX ||
                    tv64.tv_usec < 0 || tv64.tv_usec >= 1000000)
                        return (EDOM);

                tv_p->tv_sec = tv64.tv_sec;
                tv_p->tv_usec = tv64.tv_usec;
        } else {
                struct user32_timeval   tv32;

                if (sopt->sopt_valsize < sizeof (tv32))
                        return (EINVAL);

                sopt->sopt_valsize = sizeof (tv32);
                if (sopt->sopt_p != kernproc) {
                        error = copyin(sopt->sopt_val, &tv32, sizeof (tv32));
                        if (error != 0) {
                                return (error);
                        }
                } else {
                        bcopy(CAST_DOWN(caddr_t, sopt->sopt_val), &tv32,
                            sizeof (tv32));
                }
#ifndef __LP64__
                /*
                 * K64todo "comparison is always false due to
                 * limited range of data type"
                 */
                if (tv32.tv_sec < 0 || tv32.tv_sec > LONG_MAX ||
                    tv32.tv_usec < 0 || tv32.tv_usec >= 1000000)
                        return (EDOM);
#endif
                tv_p->tv_sec = tv32.tv_sec;
                tv_p->tv_usec = tv32.tv_usec;
        }
        return (0);
}

/*
 * Returns:     0                       Success
 *              EINVAL
 *              ENOPROTOOPT
 *              ENOBUFS
 *              EDOM
 *      sooptcopyin:EINVAL
 *      sooptcopyin:EFAULT
 *      sooptcopyin_timeval:EINVAL
 *      sooptcopyin_timeval:EFAULT
 *      sooptcopyin_timeval:EDOM
 *      <pr_ctloutput>:EOPNOTSUPP[AF_UNIX]
 *      <pr_ctloutput>:???w
 *      sflt_attach_private:???         [whatever a filter author chooses]
 *      <sf_setoption>:???              [whatever a filter author chooses]
 *
 * Notes:       Other <pru_listen> returns depend on the protocol family; all
 *              <sf_listen> returns depend on what the filter author causes
 *              their filter to return.
 */
int
sosetoptlock(struct socket *so, struct sockopt *sopt, int dolock)
{
        int     error, optval;
        struct  linger l;
        struct  timeval tv;
#if CONFIG_MACF_SOCKET
        struct mac extmac;
#endif /* MAC_SOCKET */

        if (sopt->sopt_dir != SOPT_SET)
                sopt->sopt_dir = SOPT_SET;

        if (dolock)
                socket_lock(so, 1);

        if ((so->so_state & (SS_CANTRCVMORE | SS_CANTSENDMORE)) ==
            (SS_CANTRCVMORE | SS_CANTSENDMORE) &&
            (so->so_flags & SOF_NPX_SETOPTSHUT) == 0) {
                /* the socket has been shutdown, no more sockopt's */
                error = EINVAL;
                goto out;
        }

        error = sflt_setsockopt(so, sopt);
        if (error != 0) {
                if (error == EJUSTRETURN)
                        error = 0;
                goto out;
        }

        if (sopt->sopt_level != SOL_SOCKET) {
                if (so->so_proto != NULL &&
                    so->so_proto->pr_ctloutput != NULL) {
                        error = (*so->so_proto->pr_ctloutput)(so, sopt);
                        goto out;
                }
                error = ENOPROTOOPT;
        } else {
                /*
                 * Allow socket-level (SOL_SOCKET) options to be filtered by
                 * the protocol layer, if needed.  A zero value returned from
                 * the handler means use default socket-level processing as
                 * done by the rest of this routine.  Otherwise, any other
                 * return value indicates that the option is unsupported.
                 */
                if (so->so_proto != NULL && (error = so->so_proto->pr_usrreqs->
                    pru_socheckopt(so, sopt)) != 0)
                        goto out;

                error = 0;
                switch (sopt->sopt_name) {
                case SO_LINGER:
                case SO_LINGER_SEC:
                        error = sooptcopyin(sopt, &l, sizeof (l), sizeof (l));
                        if (error != 0)
                                goto out;

                        so->so_linger = (sopt->sopt_name == SO_LINGER) ?
                            l.l_linger : l.l_linger * hz;
                        if (l.l_onoff != 0)
                                so->so_options |= SO_LINGER;
                        else
                                so->so_options &= ~SO_LINGER;
                        break;

                case SO_DEBUG:
                case SO_KEEPALIVE:
                case SO_DONTROUTE:
                case SO_USELOOPBACK:
                case SO_BROADCAST:
                case SO_REUSEADDR:
                case SO_REUSEPORT:
                case SO_OOBINLINE:
                case SO_TIMESTAMP:
                case SO_TIMESTAMP_MONOTONIC:
                case SO_DONTTRUNC:
                case SO_WANTMORE:
                case SO_WANTOOBFLAG:
                case SO_NOWAKEFROMSLEEP:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval)
                                so->so_options |= sopt->sopt_name;
                        else
                                so->so_options &= ~sopt->sopt_name;
                        break;

                case SO_SNDBUF:
                case SO_RCVBUF:
                case SO_SNDLOWAT:
                case SO_RCVLOWAT:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;

                        /*
                         * Values < 1 make no sense for any of these
                         * options, so disallow them.
                         */
                        if (optval < 1) {
                                error = EINVAL;
                                goto out;
                        }

                        switch (sopt->sopt_name) {
                        case SO_SNDBUF:
                        case SO_RCVBUF: {
                                struct sockbuf *sb =
                                    (sopt->sopt_name == SO_SNDBUF) ?
                                    &so->so_snd : &so->so_rcv;
                                if (sbreserve(sb, (u_int32_t)optval) == 0) {
                                        error = ENOBUFS;
                                        goto out;
                                }
                                sb->sb_flags |= SB_USRSIZE;
                                sb->sb_flags &= ~SB_AUTOSIZE;
                                sb->sb_idealsize = (u_int32_t)optval;
                                break;
                        }
                        /*
                         * Make sure the low-water is never greater than
                         * the high-water.
                         */
                        case SO_SNDLOWAT: {
                                int space = sbspace(&so->so_snd);
                                u_int32_t hiwat = so->so_snd.sb_hiwat;

                                if (so->so_snd.sb_flags & SB_UNIX) {
                                        struct unpcb *unp =
                                            (struct unpcb *)(so->so_pcb);
                                        if (unp != NULL &&
                                            unp->unp_conn != NULL) {
                                                hiwat += unp->unp_conn->unp_cc;
                                        }
                                }

                                so->so_snd.sb_lowat =
                                    (optval > hiwat) ?
                                    hiwat : optval;

                                if (space >= so->so_snd.sb_lowat) {
                                        sowwakeup(so);
                                }
                                break;
                        }
                        case SO_RCVLOWAT: {
                                int64_t data_len;
                                so->so_rcv.sb_lowat =
                                    (optval > so->so_rcv.sb_hiwat) ?
                                    so->so_rcv.sb_hiwat : optval;
                                data_len = so->so_rcv.sb_cc
                                    - so->so_rcv.sb_ctl;
                                if (data_len >= so->so_rcv.sb_lowat)
                                    sorwakeup(so);
                                break;
                        }
                        }
                        break;

                case SO_SNDTIMEO:
                case SO_RCVTIMEO:
                        error = sooptcopyin_timeval(sopt, &tv);
                        if (error != 0)
                                goto out;

                        switch (sopt->sopt_name) {
                        case SO_SNDTIMEO:
                                so->so_snd.sb_timeo = tv;
                                break;
                        case SO_RCVTIMEO:
                                so->so_rcv.sb_timeo = tv;
                                break;
                        }
                        break;

                case SO_NKE: {
                        struct so_nke nke;

                        error = sooptcopyin(sopt, &nke, sizeof (nke),
                            sizeof (nke));
                        if (error != 0)
                                goto out;

                        error = sflt_attach_internal(so, nke.nke_handle);
                        break;
                }

                case SO_NOSIGPIPE:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval != 0)
                                so->so_flags |= SOF_NOSIGPIPE;
                        else
                                so->so_flags &= ~SOF_NOSIGPIPE;
                        break;

                case SO_NOADDRERR:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval != 0)
                                so->so_flags |= SOF_NOADDRAVAIL;
                        else
                                so->so_flags &= ~SOF_NOADDRAVAIL;
                        break;

                case SO_REUSESHAREUID:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval != 0)
                                so->so_flags |= SOF_REUSESHAREUID;
                        else
                                so->so_flags &= ~SOF_REUSESHAREUID;
                        break;

                case SO_NOTIFYCONFLICT:
                        if (kauth_cred_issuser(kauth_cred_get()) == 0) {
                                error = EPERM;
                                goto out;
                        }
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval != 0)
                                so->so_flags |= SOF_NOTIFYCONFLICT;
                        else
                                so->so_flags &= ~SOF_NOTIFYCONFLICT;
                        break;

                case SO_RESTRICTIONS:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;

                        error = so_set_restrictions(so, optval);
                        break;

                case SO_AWDL_UNRESTRICTED:
                        if (SOCK_DOM(so) != PF_INET &&
                            SOCK_DOM(so) != PF_INET6) {
                                error = EOPNOTSUPP;
                                goto out;
                        }
                        error = sooptcopyin(sopt, &optval, sizeof(optval),
                            sizeof(optval));
                        if (error != 0)
                                goto out;
                        if (optval != 0) {
                                kauth_cred_t cred =  NULL;
                                proc_t ep = PROC_NULL;

                                if (so->so_flags & SOF_DELEGATED) {
                                        ep = proc_find(so->e_pid);
                                        if (ep)
                                                cred = kauth_cred_proc_ref(ep);
                                }
                                error = priv_check_cred(
                                    cred ? cred : so->so_cred,
                                    PRIV_NET_RESTRICTED_AWDL, 0);
                                if (error == 0)
                                        inp_set_awdl_unrestricted(
                                            sotoinpcb(so));
                                if (cred)
                                        kauth_cred_unref(&cred);
                                if (ep != PROC_NULL)
                                        proc_rele(ep);
                        } else
                                inp_clear_awdl_unrestricted(sotoinpcb(so));
                        break;

                case SO_LABEL:
#if CONFIG_MACF_SOCKET
                        if ((error = sooptcopyin(sopt, &extmac, sizeof (extmac),
                            sizeof (extmac))) != 0)
                                goto out;

                        error = mac_setsockopt_label(proc_ucred(sopt->sopt_p),
                            so, &extmac);
#else
                        error = EOPNOTSUPP;
#endif /* MAC_SOCKET */
                        break;

                case SO_UPCALLCLOSEWAIT:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval != 0)
                                so->so_flags |= SOF_UPCALLCLOSEWAIT;
                        else
                                so->so_flags &= ~SOF_UPCALLCLOSEWAIT;
                        break;

                case SO_RANDOMPORT:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval != 0)
                                so->so_flags |= SOF_BINDRANDOMPORT;
                        else
                                so->so_flags &= ~SOF_BINDRANDOMPORT;
                        break;

                case SO_NP_EXTENSIONS: {
                        struct so_np_extensions sonpx;

                        error = sooptcopyin(sopt, &sonpx, sizeof (sonpx),
                            sizeof (sonpx));
                        if (error != 0)
                                goto out;
                        if (sonpx.npx_mask & ~SONPX_MASK_VALID) {
                                error = EINVAL;
                                goto out;
                        }
                        /*
                         * Only one bit defined for now
                         */
                        if ((sonpx.npx_mask & SONPX_SETOPTSHUT)) {
                                if ((sonpx.npx_flags & SONPX_SETOPTSHUT))
                                        so->so_flags |= SOF_NPX_SETOPTSHUT;
                                else
                                        so->so_flags &= ~SOF_NPX_SETOPTSHUT;
                        }
                        break;
                }

                case SO_TRAFFIC_CLASS: {
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        error = so_set_traffic_class(so, optval);
                        if (error != 0)
                                goto out;
                        break;
                }

                case SO_RECV_TRAFFIC_CLASS: {
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval == 0)
                                so->so_flags &= ~SOF_RECV_TRAFFIC_CLASS;
                        else
                                so->so_flags |= SOF_RECV_TRAFFIC_CLASS;
                        break;
                }

                case SO_TRAFFIC_CLASS_DBG: {
                        struct so_tcdbg so_tcdbg;

                        error = sooptcopyin(sopt, &so_tcdbg,
                            sizeof (struct so_tcdbg), sizeof (struct so_tcdbg));
                        if (error != 0)
                                goto out;
                        error = so_set_tcdbg(so, &so_tcdbg);
                        if (error != 0)
                                goto out;
                        break;
                }

                case SO_PRIVILEGED_TRAFFIC_CLASS:
                        error = priv_check_cred(kauth_cred_get(),
                            PRIV_NET_PRIVILEGED_TRAFFIC_CLASS, 0);
                        if (error != 0)
                                goto out;
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval == 0)
                                so->so_flags &= ~SOF_PRIVILEGED_TRAFFIC_CLASS;
                        else
                                so->so_flags |= SOF_PRIVILEGED_TRAFFIC_CLASS;
                        break;

                case SO_DEFUNCTOK:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0 || (so->so_flags & SOF_DEFUNCT)) {
                                if (error == 0)
                                        error = EBADF;
                                goto out;
                        }
                        /*
                         * Any process can set SO_DEFUNCTOK (clear
                         * SOF_NODEFUNCT), but only root can clear
                         * SO_DEFUNCTOK (set SOF_NODEFUNCT).
                         */
                        if (optval == 0 &&
                            kauth_cred_issuser(kauth_cred_get()) == 0) {
                                error = EPERM;
                                goto out;
                        }
                        if (optval)
                                so->so_flags &= ~SOF_NODEFUNCT;
                        else
                                so->so_flags |= SOF_NODEFUNCT;

                        if (SOCK_DOM(so) == PF_INET ||
                            SOCK_DOM(so) == PF_INET6) {
                                char s[MAX_IPv6_STR_LEN];
                                char d[MAX_IPv6_STR_LEN];
                                struct inpcb *inp = sotoinpcb(so);

                                SODEFUNCTLOG(("%s[%d]: so 0x%llx [%s %s:%d -> "
                                    "%s:%d] is now marked as %seligible for "
                                    "defunct\n", __func__, proc_selfpid(),
                                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                                    (SOCK_TYPE(so) == SOCK_STREAM) ?
                                    "TCP" : "UDP", inet_ntop(SOCK_DOM(so),
                                    ((SOCK_DOM(so) == PF_INET) ?
                                    (void *)&inp->inp_laddr.s_addr :
                                    (void *)&inp->in6p_laddr), s, sizeof (s)),
                                    ntohs(inp->in6p_lport),
                                    inet_ntop(SOCK_DOM(so),
                                    (SOCK_DOM(so) == PF_INET) ?
                                    (void *)&inp->inp_faddr.s_addr :
                                    (void *)&inp->in6p_faddr, d, sizeof (d)),
                                    ntohs(inp->in6p_fport),
                                    (so->so_flags & SOF_NODEFUNCT) ?
                                    "not " : ""));
                        } else {
                                SODEFUNCTLOG(("%s[%d]: so 0x%llx [%d,%d] is "
                                    "now marked as %seligible for defunct\n",
                                    __func__, proc_selfpid(),
                                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                                    SOCK_DOM(so), SOCK_TYPE(so),
                                    (so->so_flags & SOF_NODEFUNCT) ?
                                    "not " : ""));
                        }
                        break;

                case SO_ISDEFUNCT:
                        /* This option is not settable */
                        error = EINVAL;
                        break;

                case SO_OPPORTUNISTIC:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error == 0)
                                error = so_set_opportunistic(so, optval);
                        break;

                case SO_FLUSH:
                        /* This option is handled by lower layer(s) */
                        error = 0;
                        break;

                case SO_RECV_ANYIF:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error == 0)
                                error = so_set_recv_anyif(so, optval);
                        break;

                case SO_TRAFFIC_MGT_BACKGROUND: {
                        /* This option is handled by lower layer(s) */
                        error = 0;
                        break;
                }

#if FLOW_DIVERT
                case SO_FLOW_DIVERT_TOKEN:
                        error = flow_divert_token_set(so, sopt);
                        break;
#endif  /* FLOW_DIVERT */


                case SO_DELEGATED:
                        if ((error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval))) != 0)
                                break;

                        error = so_set_effective_pid(so, optval, sopt->sopt_p);
                        break;

                case SO_DELEGATED_UUID: {
                        uuid_t euuid;

                        if ((error = sooptcopyin(sopt, &euuid, sizeof (euuid),
                            sizeof (euuid))) != 0)
                                break;

                        error = so_set_effective_uuid(so, euuid, sopt->sopt_p);
                        break;
                }

#if NECP
                case SO_NECP_ATTRIBUTES:
                        error = necp_set_socket_attributes(so, sopt);
                        break;
#endif /* NECP */

#if MPTCP
                case SO_MPTCP_FASTJOIN:
                        if (!((so->so_flags & SOF_MP_SUBFLOW) ||
                            ((SOCK_CHECK_DOM(so, PF_MULTIPATH)) &&
                            (SOCK_CHECK_PROTO(so, IPPROTO_TCP))))) {
                                error = ENOPROTOOPT;
                                break;
                        }

                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error != 0)
                                goto out;
                        if (optval == 0)
                                so->so_flags &= ~SOF_MPTCP_FASTJOIN;
                        else
                                so->so_flags |= SOF_MPTCP_FASTJOIN;
                        break;
#endif /* MPTCP */

                case SO_EXTENDED_BK_IDLE:
                        error = sooptcopyin(sopt, &optval, sizeof (optval),
                            sizeof (optval));
                        if (error == 0)
                                error = so_set_extended_bk_idle(so, optval);
                        break;

                default:
                        error = ENOPROTOOPT;
                        break;
                }
                if (error == 0 && so->so_proto != NULL &&
                    so->so_proto->pr_ctloutput != NULL) {
                        (void) so->so_proto->pr_ctloutput(so, sopt);
                }
        }
out:
        if (dolock)
                socket_unlock(so, 1);
        return (error);
}

/* Helper routines for getsockopt */
int
sooptcopyout(struct sockopt *sopt, void *buf, size_t len)
{
        int     error;
        size_t  valsize;

        error = 0;

        /*
         * Documented get behavior is that we always return a value,
         * possibly truncated to fit in the user's buffer.
         * Traditional behavior is that we always tell the user
         * precisely how much we copied, rather than something useful
         * like the total amount we had available for her.
         * Note that this interface is not idempotent; the entire answer must
         * generated ahead of time.
         */
        valsize = min(len, sopt->sopt_valsize);
        sopt->sopt_valsize = valsize;
        if (sopt->sopt_val != USER_ADDR_NULL) {
                if (sopt->sopt_p != kernproc)
                        error = copyout(buf, sopt->sopt_val, valsize);
                else
                        bcopy(buf, CAST_DOWN(caddr_t, sopt->sopt_val), valsize);
        }
        return (error);
}

static int
sooptcopyout_timeval(struct sockopt *sopt, const struct timeval *tv_p)
{
        int                     error;
        size_t                  len;
        struct user64_timeval   tv64;
        struct user32_timeval   tv32;
        const void *            val;
        size_t                  valsize;

        error = 0;
        if (proc_is64bit(sopt->sopt_p)) {
                len = sizeof (tv64);
                tv64.tv_sec = tv_p->tv_sec;
                tv64.tv_usec = tv_p->tv_usec;
                val = &tv64;
        } else {
                len = sizeof (tv32);
                tv32.tv_sec = tv_p->tv_sec;
                tv32.tv_usec = tv_p->tv_usec;
                val = &tv32;
        }
        valsize = min(len, sopt->sopt_valsize);
        sopt->sopt_valsize = valsize;
        if (sopt->sopt_val != USER_ADDR_NULL) {
                if (sopt->sopt_p != kernproc)
                        error = copyout(val, sopt->sopt_val, valsize);
                else
                        bcopy(val, CAST_DOWN(caddr_t, sopt->sopt_val), valsize);
        }
        return (error);
}

/*
 * Return:      0                       Success
 *              ENOPROTOOPT
 *      <pr_ctloutput>:EOPNOTSUPP[AF_UNIX]
 *      <pr_ctloutput>:???
 *      <sf_getoption>:???
 */
int
sogetoptlock(struct socket *so, struct sockopt *sopt, int dolock)
{
        int     error, optval;
        struct  linger l;
        struct  timeval tv;
#if CONFIG_MACF_SOCKET
        struct mac extmac;
#endif /* MAC_SOCKET */

        if (sopt->sopt_dir != SOPT_GET)
                sopt->sopt_dir = SOPT_GET;

        if (dolock)
                socket_lock(so, 1);

        error = sflt_getsockopt(so, sopt);
        if (error != 0) {
                if (error == EJUSTRETURN)
                        error = 0;
                goto out;
        }

        if (sopt->sopt_level != SOL_SOCKET) {
                if (so->so_proto != NULL &&
                    so->so_proto->pr_ctloutput != NULL) {
                        error = (*so->so_proto->pr_ctloutput)(so, sopt);
                        goto out;
                }
                error = ENOPROTOOPT;
        } else {
                /*
                 * Allow socket-level (SOL_SOCKET) options to be filtered by
                 * the protocol layer, if needed.  A zero value returned from
                 * the handler means use default socket-level processing as
                 * done by the rest of this routine.  Otherwise, any other
                 * return value indicates that the option is unsupported.
                 */
                if (so->so_proto != NULL && (error = so->so_proto->pr_usrreqs->
                    pru_socheckopt(so, sopt)) != 0)
                        goto out;

                error = 0;
                switch (sopt->sopt_name) {
                case SO_LINGER:
                case SO_LINGER_SEC:
                        l.l_onoff = ((so->so_options & SO_LINGER) ? 1 : 0);
                        l.l_linger = (sopt->sopt_name == SO_LINGER) ?
                            so->so_linger : so->so_linger / hz;
                        error = sooptcopyout(sopt, &l, sizeof (l));
                        break;

                case SO_USELOOPBACK:
                case SO_DONTROUTE:
                case SO_DEBUG:
                case SO_KEEPALIVE:
                case SO_REUSEADDR:
                case SO_REUSEPORT:
                case SO_BROADCAST:
                case SO_OOBINLINE:
                case SO_TIMESTAMP:
                case SO_TIMESTAMP_MONOTONIC:
                case SO_DONTTRUNC:
                case SO_WANTMORE:
                case SO_WANTOOBFLAG:
                case SO_NOWAKEFROMSLEEP:
                        optval = so->so_options & sopt->sopt_name;
integer:
                        error = sooptcopyout(sopt, &optval, sizeof (optval));
                        break;

                case SO_TYPE:
                        optval = so->so_type;
                        goto integer;

                case SO_NREAD:
                        if (so->so_proto->pr_flags & PR_ATOMIC) {
                                int pkt_total;
                                struct mbuf *m1;

                                pkt_total = 0;
                                m1 = so->so_rcv.sb_mb;
                                while (m1 != NULL) {
                                        if (m1->m_type == MT_DATA ||
                                            m1->m_type == MT_HEADER ||
                                            m1->m_type == MT_OOBDATA)
                                                pkt_total += m1->m_len;
                                        m1 = m1->m_next;
                                }
                                optval = pkt_total;
                        } else {
                                optval = so->so_rcv.sb_cc - so->so_rcv.sb_ctl;
                        }
                        goto integer;

                case SO_NUMRCVPKT:
                        if (so->so_proto->pr_flags & PR_ATOMIC) {
                                int cnt = 0;
                                struct mbuf *m1;

                                m1 = so->so_rcv.sb_mb;
                                while (m1 != NULL) {
                                        if (m1->m_type == MT_DATA ||
                                            m1->m_type == MT_HEADER ||
                                            m1->m_type == MT_OOBDATA)
                                                cnt += 1;
                                        m1 = m1->m_nextpkt;
                                }
                                optval = cnt;
                                goto integer;
                        } else {
                                error = EINVAL;
                                break;
                        }

                case SO_NWRITE:
                        optval = so->so_snd.sb_cc;
                        goto integer;

                case SO_ERROR:
                        optval = so->so_error;
                        so->so_error = 0;
                        goto integer;

                case SO_SNDBUF: {
                        u_int32_t hiwat = so->so_snd.sb_hiwat;

                        if (so->so_snd.sb_flags & SB_UNIX) {
                                struct unpcb *unp =
                                    (struct unpcb *)(so->so_pcb);
                                if (unp != NULL && unp->unp_conn != NULL) {
                                        hiwat += unp->unp_conn->unp_cc;
                                }
                        }

                        optval = hiwat;
                        goto integer;
                }
                case SO_RCVBUF:
                        optval = so->so_rcv.sb_hiwat;
                        goto integer;

                case SO_SNDLOWAT:
                        optval = so->so_snd.sb_lowat;
                        goto integer;

                case SO_RCVLOWAT:
                        optval = so->so_rcv.sb_lowat;
                        goto integer;

                case SO_SNDTIMEO:
                case SO_RCVTIMEO:
                        tv = (sopt->sopt_name == SO_SNDTIMEO ?
                            so->so_snd.sb_timeo : so->so_rcv.sb_timeo);

                        error = sooptcopyout_timeval(sopt, &tv);
                        break;

                case SO_NOSIGPIPE:
                        optval = (so->so_flags & SOF_NOSIGPIPE);
                        goto integer;

                case SO_NOADDRERR:
                        optval = (so->so_flags & SOF_NOADDRAVAIL);
                        goto integer;

                case SO_REUSESHAREUID:
                        optval = (so->so_flags & SOF_REUSESHAREUID);
                        goto integer;


                case SO_NOTIFYCONFLICT:
                        optval = (so->so_flags & SOF_NOTIFYCONFLICT);
                        goto integer;

                case SO_RESTRICTIONS:
                        optval = so_get_restrictions(so);
                        goto integer;

                case SO_AWDL_UNRESTRICTED:
                        if (SOCK_DOM(so) == PF_INET ||
                            SOCK_DOM(so) == PF_INET6) {
                                optval = inp_get_awdl_unrestricted(
                                    sotoinpcb(so));
                                goto integer;
                        } else
                                error = EOPNOTSUPP;
                        break;

                case SO_LABEL:
#if CONFIG_MACF_SOCKET
                        if ((error = sooptcopyin(sopt, &extmac, sizeof (extmac),
                            sizeof (extmac))) != 0 ||
                            (error = mac_socket_label_get(proc_ucred(
                            sopt->sopt_p), so, &extmac)) != 0)
                                break;

                        error = sooptcopyout(sopt, &extmac, sizeof (extmac));
#else
                        error = EOPNOTSUPP;
#endif /* MAC_SOCKET */
                        break;

                case SO_PEERLABEL:
#if CONFIG_MACF_SOCKET
                        if ((error = sooptcopyin(sopt, &extmac, sizeof (extmac),
                            sizeof (extmac))) != 0 ||
                            (error = mac_socketpeer_label_get(proc_ucred(
                            sopt->sopt_p), so, &extmac)) != 0)
                                break;

                        error = sooptcopyout(sopt, &extmac, sizeof (extmac));
#else
                        error = EOPNOTSUPP;
#endif /* MAC_SOCKET */
                        break;

#ifdef __APPLE_API_PRIVATE
                case SO_UPCALLCLOSEWAIT:
                        optval = (so->so_flags & SOF_UPCALLCLOSEWAIT);
                        goto integer;
#endif
                case SO_RANDOMPORT:
                        optval = (so->so_flags & SOF_BINDRANDOMPORT);
                        goto integer;

                case SO_NP_EXTENSIONS: {
                        struct so_np_extensions sonpx;

                        sonpx.npx_flags = (so->so_flags & SOF_NPX_SETOPTSHUT) ?
                            SONPX_SETOPTSHUT : 0;
                        sonpx.npx_mask = SONPX_MASK_VALID;

                        error = sooptcopyout(sopt, &sonpx,
                            sizeof (struct so_np_extensions));
                        break;
                }

                case SO_TRAFFIC_CLASS:
                        optval = so->so_traffic_class;
                        goto integer;

                case SO_RECV_TRAFFIC_CLASS:
                        optval = (so->so_flags & SOF_RECV_TRAFFIC_CLASS);
                        goto integer;

                case SO_TRAFFIC_CLASS_STATS:
                        error = sooptcopyout(sopt, &so->so_tc_stats,
                            sizeof (so->so_tc_stats));
                        break;

                case SO_TRAFFIC_CLASS_DBG:
                        error = sogetopt_tcdbg(so, sopt);
                        break;

                case SO_PRIVILEGED_TRAFFIC_CLASS:
                        optval = (so->so_flags & SOF_PRIVILEGED_TRAFFIC_CLASS);
                        goto integer;

                case SO_DEFUNCTOK:
                        optval = !(so->so_flags & SOF_NODEFUNCT);
                        goto integer;

                case SO_ISDEFUNCT:
                        optval = (so->so_flags & SOF_DEFUNCT);
                        goto integer;

                case SO_OPPORTUNISTIC:
                        optval = so_get_opportunistic(so);
                        goto integer;

                case SO_FLUSH:
                        /* This option is not gettable */
                        error = EINVAL;
                        break;

                case SO_RECV_ANYIF:
                        optval = so_get_recv_anyif(so);
                        goto integer;

                case SO_TRAFFIC_MGT_BACKGROUND:
                        /* This option is handled by lower layer(s) */
                        if (so->so_proto != NULL &&
                            so->so_proto->pr_ctloutput != NULL) {
                                (void) so->so_proto->pr_ctloutput(so, sopt);
                        }
                        break;

#if FLOW_DIVERT
                case SO_FLOW_DIVERT_TOKEN:
                        error = flow_divert_token_get(so, sopt);
                        break;
#endif  /* FLOW_DIVERT */

#if NECP
                case SO_NECP_ATTRIBUTES:
                        error = necp_get_socket_attributes(so, sopt);
                        break;
#endif /* NECP */

#if CONTENT_FILTER
                case SO_CFIL_SOCK_ID: {
                        cfil_sock_id_t sock_id;

                        sock_id = cfil_sock_id_from_socket(so);

                        error = sooptcopyout(sopt, &sock_id,
                                sizeof(cfil_sock_id_t));
                        break;
                }
#endif  /* CONTENT_FILTER */

#if MPTCP
                case SO_MPTCP_FASTJOIN:
                        if (!((so->so_flags & SOF_MP_SUBFLOW) ||
                            ((SOCK_CHECK_DOM(so, PF_MULTIPATH)) &&
                            (SOCK_CHECK_PROTO(so, IPPROTO_TCP))))) {
                                error = ENOPROTOOPT;
                                break;
                        }
                        optval = (so->so_flags & SOF_MPTCP_FASTJOIN);
                        /* Fixed along with rdar://19391339 */
                        goto integer;
#endif /* MPTCP */

                case SO_EXTENDED_BK_IDLE:
                        optval = (so->so_flags1 & SOF1_EXTEND_BK_IDLE_WANTED);
                        goto integer;

                default:
                        error = ENOPROTOOPT;
                        break;
                }
        }
out:
        if (dolock)
                socket_unlock(so, 1);
        return (error);
}

/*
 * The size limits on our soopt_getm is different from that on FreeBSD.
 * We limit the size of options to MCLBYTES. This will have to change
 * if we need to define options that need more space than MCLBYTES.
 */
int
soopt_getm(struct sockopt *sopt, struct mbuf **mp)
{
        struct mbuf *m, *m_prev;
        int sopt_size = sopt->sopt_valsize;
        int how;

        if (sopt_size <= 0 || sopt_size > MCLBYTES)
                return (EMSGSIZE);

        how = sopt->sopt_p != kernproc ? M_WAIT : M_DONTWAIT;
        MGET(m, how, MT_DATA);
        if (m == NULL)
                return (ENOBUFS);
        if (sopt_size > MLEN) {
                MCLGET(m, how);
                if ((m->m_flags & M_EXT) == 0) {
                        m_free(m);
                        return (ENOBUFS);
                }
                m->m_len = min(MCLBYTES, sopt_size);
        } else {
                m->m_len = min(MLEN, sopt_size);
        }
        sopt_size -= m->m_len;
        *mp = m;
        m_prev = m;

        while (sopt_size > 0) {
                MGET(m, how, MT_DATA);
                if (m == NULL) {
                        m_freem(*mp);
                        return (ENOBUFS);
                }
                if (sopt_size > MLEN) {
                        MCLGET(m, how);
                        if ((m->m_flags & M_EXT) == 0) {
                                m_freem(*mp);
                                m_freem(m);
                                return (ENOBUFS);
                        }
                        m->m_len = min(MCLBYTES, sopt_size);
                } else {
                        m->m_len = min(MLEN, sopt_size);
                }
                sopt_size -= m->m_len;
                m_prev->m_next = m;
                m_prev = m;
        }
        return (0);
}

/* copyin sopt data into mbuf chain */
int
soopt_mcopyin(struct sockopt *sopt, struct mbuf *m)
{
        struct mbuf *m0 = m;

        if (sopt->sopt_val == USER_ADDR_NULL)
                return (0);
        while (m != NULL && sopt->sopt_valsize >= m->m_len) {
                if (sopt->sopt_p != kernproc) {
                        int error;

                        error = copyin(sopt->sopt_val, mtod(m, char *),
                            m->m_len);
                        if (error != 0) {
                                m_freem(m0);
                                return (error);
                        }
                } else {
                        bcopy(CAST_DOWN(caddr_t, sopt->sopt_val),
                            mtod(m, char *), m->m_len);
                }
                sopt->sopt_valsize -= m->m_len;
                sopt->sopt_val += m->m_len;
                m = m->m_next;
        }
        /* should be allocated enoughly at ip6_sooptmcopyin() */
        if (m != NULL) {
                panic("soopt_mcopyin");
                /* NOTREACHED */
        }
        return (0);
}

/* copyout mbuf chain data into soopt */
int
soopt_mcopyout(struct sockopt *sopt, struct mbuf *m)
{
        struct mbuf *m0 = m;
        size_t valsize = 0;

        if (sopt->sopt_val == USER_ADDR_NULL)
                return (0);
        while (m != NULL && sopt->sopt_valsize >= m->m_len) {
                if (sopt->sopt_p != kernproc) {
                        int error;

                        error = copyout(mtod(m, char *), sopt->sopt_val,
                            m->m_len);
                        if (error != 0) {
                                m_freem(m0);
                                return (error);
                        }
                } else {
                        bcopy(mtod(m, char *),
                            CAST_DOWN(caddr_t, sopt->sopt_val), m->m_len);
                }
                sopt->sopt_valsize -= m->m_len;
                sopt->sopt_val += m->m_len;
                valsize += m->m_len;
                m = m->m_next;
        }
        if (m != NULL) {
                /* enough soopt buffer should be given from user-land */
                m_freem(m0);
                return (EINVAL);
        }
        sopt->sopt_valsize = valsize;
        return (0);
}

void
sohasoutofband(struct socket *so)
{
        if (so->so_pgid < 0)
                gsignal(-so->so_pgid, SIGURG);
        else if (so->so_pgid > 0)
                proc_signal(so->so_pgid, SIGURG);
        selwakeup(&so->so_rcv.sb_sel);
}

int
sopoll(struct socket *so, int events, kauth_cred_t cred, void * wql)
{
#pragma unused(cred)
        struct proc *p = current_proc();
        int revents = 0;

        socket_lock(so, 1);
        so_update_last_owner_locked(so, PROC_NULL);
        so_update_policy(so);

        if (events & (POLLIN | POLLRDNORM))
                if (soreadable(so))
                        revents |= events & (POLLIN | POLLRDNORM);

        if (events & (POLLOUT | POLLWRNORM))
                if (sowriteable(so))
                        revents |= events & (POLLOUT | POLLWRNORM);

        if (events & (POLLPRI | POLLRDBAND))
                if (so->so_oobmark || (so->so_state & SS_RCVATMARK))
                        revents |= events & (POLLPRI | POLLRDBAND);

        if (revents == 0) {
                if (events & (POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND)) {
                        /*
                         * Darwin sets the flag first,
                         * BSD calls selrecord first
                         */
                        so->so_rcv.sb_flags |= SB_SEL;
                        selrecord(p, &so->so_rcv.sb_sel, wql);
                }

                if (events & (POLLOUT | POLLWRNORM)) {
                        /*
                         * Darwin sets the flag first,
                         * BSD calls selrecord first
                         */
                        so->so_snd.sb_flags |= SB_SEL;
                        selrecord(p, &so->so_snd.sb_sel, wql);
                }
        }

        socket_unlock(so, 1);
        return (revents);
}

int
soo_kqfilter(struct fileproc *fp, struct knote *kn, vfs_context_t ctx)
{
#pragma unused(fp)
#if !CONFIG_MACF_SOCKET
#pragma unused(ctx)
#endif /* MAC_SOCKET */
        struct socket *so = (struct socket *)kn->kn_fp->f_fglob->fg_data;
        struct klist *skl;

        socket_lock(so, 1);
        so_update_last_owner_locked(so, PROC_NULL);
        so_update_policy(so);

#if CONFIG_MACF_SOCKET
        if (mac_socket_check_kqfilter(proc_ucred(vfs_context_proc(ctx)),
            kn, so) != 0) {
                socket_unlock(so, 1);
                return (1);
        }
#endif /* MAC_SOCKET */

        switch (kn->kn_filter) {
        case EVFILT_READ:
                kn->kn_fop = &soread_filtops;
                /*
                 * If the caller explicitly asked for OOB results (e.g. poll()),
                 * save that off in the hookid field and reserve the kn_flags
                 * EV_OOBAND bit for output only.
                 */
                if (kn->kn_flags & EV_OOBAND) {
                        kn->kn_flags &= ~EV_OOBAND;
                        kn->kn_hookid = EV_OOBAND;
                } else {
                        kn->kn_hookid = 0;
                }
                skl = &so->so_rcv.sb_sel.si_note;
                break;
        case EVFILT_WRITE:
                kn->kn_fop = &sowrite_filtops;
                skl = &so->so_snd.sb_sel.si_note;
                break;
        case EVFILT_SOCK:
                kn->kn_fop = &sock_filtops;
                skl = &so->so_klist;
                kn->kn_hookid = 0;
                kn->kn_status |= KN_TOUCH;
                break;
        default:
                socket_unlock(so, 1);
                return (1);
        }

        if (KNOTE_ATTACH(skl, kn)) {
                switch (kn->kn_filter) {
                case EVFILT_READ:
                        so->so_rcv.sb_flags |= SB_KNOTE;
                        break;
                case EVFILT_WRITE:
                        so->so_snd.sb_flags |= SB_KNOTE;
                        break;
                case EVFILT_SOCK:
                        so->so_flags |= SOF_KNOTE;
                        break;
                default:
                        socket_unlock(so, 1);
                        return (1);
                }
        }
        socket_unlock(so, 1);
        return (0);
}

static void
filt_sordetach(struct knote *kn)
{
        struct socket *so = (struct socket *)kn->kn_fp->f_fglob->fg_data;

        socket_lock(so, 1);
        if (so->so_rcv.sb_flags & SB_KNOTE)
                if (KNOTE_DETACH(&so->so_rcv.sb_sel.si_note, kn))
                        so->so_rcv.sb_flags &= ~SB_KNOTE;
        socket_unlock(so, 1);
}

/*ARGSUSED*/
static int
filt_soread(struct knote *kn, long hint)
{
        struct socket *so = (struct socket *)kn->kn_fp->f_fglob->fg_data;

        if ((hint & SO_FILT_HINT_LOCKED) == 0)
                socket_lock(so, 1);

        if (so->so_options & SO_ACCEPTCONN) {
                int isempty;

                /*
                 * Radar 6615193 handle the listen case dynamically
                 * for kqueue read filter. This allows to call listen()
                 * after registering the kqueue EVFILT_READ.
                 */

                kn->kn_data = so->so_qlen;
                isempty = ! TAILQ_EMPTY(&so->so_comp);

                if ((hint & SO_FILT_HINT_LOCKED) == 0)
                        socket_unlock(so, 1);

                return (isempty);
        }

        /* socket isn't a listener */
        /*
         * NOTE_LOWAT specifies new low water mark in data, i.e.
         * the bytes of protocol data. We therefore exclude any
         * control bytes.
         */
        kn->kn_data = so->so_rcv.sb_cc - so->so_rcv.sb_ctl;

        /*
         * Clear out EV_OOBAND that filt_soread may have set in the
         * past.
         */
        kn->kn_flags &= ~EV_OOBAND;
        if ((so->so_oobmark) || (so->so_state & SS_RCVATMARK)) {
                kn->kn_flags |= EV_OOBAND;
                /*
                 * If caller registered explicit interest in OOB data,
                 * return immediately (data == amount beyond mark, for
                 * legacy reasons - that should be changed later).
                 */
                if (kn->kn_hookid == EV_OOBAND) {
                        /*
                         * When so_state is SS_RCVATMARK, so_oobmark
                         * is 0.
                         */
                        kn->kn_data -= so->so_oobmark;
                        if ((hint & SO_FILT_HINT_LOCKED) == 0)
                                socket_unlock(so, 1);
                        return (1);
                }
        }

        if ((so->so_state & SS_CANTRCVMORE)
#if CONTENT_FILTER
            && cfil_sock_data_pending(&so->so_rcv) == 0
#endif /* CONTENT_FILTER */
           ) {
                kn->kn_flags |= EV_EOF;
                kn->kn_fflags = so->so_error;
                if ((hint & SO_FILT_HINT_LOCKED) == 0)
                        socket_unlock(so, 1);
                return (1);
        }

        if (so->so_error) {     /* temporary udp error */
                if ((hint & SO_FILT_HINT_LOCKED) == 0)
                        socket_unlock(so, 1);
                return (1);
        }

        int64_t lowwat = so->so_rcv.sb_lowat;
        /*
         * Ensure that when NOTE_LOWAT is used, the derived
         * low water mark is bounded by socket's rcv buf's
         * high and low water mark values.
         */
        if (kn->kn_sfflags & NOTE_LOWAT) {
                if (kn->kn_sdata > so->so_rcv.sb_hiwat)
                        lowwat = so->so_rcv.sb_hiwat;
                else if (kn->kn_sdata > lowwat)
                        lowwat = kn->kn_sdata;
        }

        if ((hint & SO_FILT_HINT_LOCKED) == 0)
                socket_unlock(so, 1);

        /*
         * The order below is important. Since NOTE_LOWAT
         * overrides sb_lowat, check for NOTE_LOWAT case
         * first.
         */
        if (kn->kn_sfflags & NOTE_LOWAT)
                return (kn->kn_data >= lowwat);

        return (so->so_rcv.sb_cc >= lowwat);
}

static void
filt_sowdetach(struct knote *kn)
{
        struct socket *so = (struct socket *)kn->kn_fp->f_fglob->fg_data;
        socket_lock(so, 1);

        if (so->so_snd.sb_flags & SB_KNOTE)
                if (KNOTE_DETACH(&so->so_snd.sb_sel.si_note, kn))
                        so->so_snd.sb_flags &= ~SB_KNOTE;
        socket_unlock(so, 1);
}

int
so_wait_for_if_feedback(struct socket *so)
{
        if ((SOCK_DOM(so) == PF_INET || SOCK_DOM(so) == PF_INET6) &&
            (so->so_state & SS_ISCONNECTED)) {
                struct inpcb *inp = sotoinpcb(so);
                if (INP_WAIT_FOR_IF_FEEDBACK(inp))
                        return (1);
        }
        return (0);
}

/*ARGSUSED*/
static int
filt_sowrite(struct knote *kn, long hint)
{
        struct socket *so = (struct socket *)kn->kn_fp->f_fglob->fg_data;
        int ret = 0;

        if ((hint & SO_FILT_HINT_LOCKED) == 0)
                socket_lock(so, 1);

        kn->kn_data = sbspace(&so->so_snd);
        if (so->so_state & SS_CANTSENDMORE) {
                kn->kn_flags |= EV_EOF;
                kn->kn_fflags = so->so_error;
                ret = 1;
                goto out;
        }
        if (so->so_error) {     /* temporary udp error */
                ret = 1;
                goto out;
        }
        if (!socanwrite(so)) {
                ret = 0;
                goto out;
        }
        if (so->so_flags1 & SOF1_PRECONNECT_DATA) {
                ret = 1;
                goto out;
        }
        int64_t lowwat = so->so_snd.sb_lowat;
        if (kn->kn_sfflags & NOTE_LOWAT) {
                if (kn->kn_sdata > so->so_snd.sb_hiwat)
                        lowwat = so->so_snd.sb_hiwat;
                else if (kn->kn_sdata > lowwat)
                        lowwat = kn->kn_sdata;
        }
        if (kn->kn_data >= lowwat) {
                if (so->so_flags & SOF_NOTSENT_LOWAT) {
                        if ((SOCK_DOM(so) == PF_INET
                            || SOCK_DOM(so) == PF_INET6)
                            && so->so_type == SOCK_STREAM) {
                                ret = tcp_notsent_lowat_check(so);
                        }
#if MPTCP
                        else if ((SOCK_DOM(so) == PF_MULTIPATH) &&
                            (SOCK_PROTO(so) == IPPROTO_TCP)) {
                                ret = mptcp_notsent_lowat_check(so);
                        }
#endif
                        else {
                                ret = 1;
                                goto out;
                        }
                } else {
                        ret = 1;
                }
        }
        if (so_wait_for_if_feedback(so))
                ret = 0;
out:
        if ((hint & SO_FILT_HINT_LOCKED) == 0)
                socket_unlock(so, 1);
        return (ret);
}

static void
filt_sockdetach(struct knote *kn)
{
        struct socket *so = (struct socket *)kn->kn_fp->f_fglob->fg_data;
        socket_lock(so, 1);

        if ((so->so_flags & SOF_KNOTE) != 0)
                if (KNOTE_DETACH(&so->so_klist, kn))
                        so->so_flags &= ~SOF_KNOTE;
        socket_unlock(so, 1);
}

static int
filt_sockev(struct knote *kn, long hint)
{
        int ret = 0, locked = 0;
        struct socket *so = (struct socket *)kn->kn_fp->f_fglob->fg_data;
        long ev_hint = (hint & SO_FILT_HINT_EV);
        uint32_t level_trigger = 0;

        if ((hint & SO_FILT_HINT_LOCKED) == 0) {
                socket_lock(so, 1);
                locked = 1;
        }

        if (ev_hint & SO_FILT_HINT_CONNRESET) {
                kn->kn_fflags |= NOTE_CONNRESET;
        }
        if (ev_hint & SO_FILT_HINT_TIMEOUT) {
                kn->kn_fflags |= NOTE_TIMEOUT;
        }
        if (ev_hint & SO_FILT_HINT_NOSRCADDR) {
                kn->kn_fflags |= NOTE_NOSRCADDR;
        }
        if (ev_hint & SO_FILT_HINT_IFDENIED) {
                kn->kn_fflags |= NOTE_IFDENIED;
        }
        if (ev_hint & SO_FILT_HINT_KEEPALIVE) {
                kn->kn_fflags |= NOTE_KEEPALIVE;
        }
        if (ev_hint & SO_FILT_HINT_ADAPTIVE_WTIMO) {
                kn->kn_fflags |= NOTE_ADAPTIVE_WTIMO;
        }
        if (ev_hint & SO_FILT_HINT_ADAPTIVE_RTIMO) {
                kn->kn_fflags |= NOTE_ADAPTIVE_RTIMO;
        }
        if ((ev_hint & SO_FILT_HINT_CONNECTED) ||
            (so->so_state & SS_ISCONNECTED)) {
                kn->kn_fflags |= NOTE_CONNECTED;
                level_trigger |= NOTE_CONNECTED;
        }
        if ((ev_hint & SO_FILT_HINT_DISCONNECTED) ||
            (so->so_state & SS_ISDISCONNECTED)) {
                kn->kn_fflags |= NOTE_DISCONNECTED;
                level_trigger |= NOTE_DISCONNECTED;
        }
        if (ev_hint & SO_FILT_HINT_CONNINFO_UPDATED) {
                if (so->so_proto != NULL &&
                    (so->so_proto->pr_flags & PR_EVCONNINFO))
                        kn->kn_fflags |= NOTE_CONNINFO_UPDATED;
        }

        if ((so->so_state & SS_CANTRCVMORE)
#if CONTENT_FILTER
            && cfil_sock_data_pending(&so->so_rcv) == 0
#endif /* CONTENT_FILTER */
            ) {
                kn->kn_fflags |= NOTE_READCLOSED;
                level_trigger |= NOTE_READCLOSED;
        }

        if (so->so_state & SS_CANTSENDMORE) {
                kn->kn_fflags |= NOTE_WRITECLOSED;
                level_trigger |= NOTE_WRITECLOSED;
        }

        if ((ev_hint & SO_FILT_HINT_SUSPEND) ||
            (so->so_flags & SOF_SUSPENDED)) {
                kn->kn_fflags &= ~(NOTE_SUSPEND | NOTE_RESUME);

                /* If resume event was delivered before, reset it */
                kn->kn_hookid &= ~NOTE_RESUME;

                kn->kn_fflags |= NOTE_SUSPEND;
                level_trigger |= NOTE_SUSPEND;
        }

        if ((ev_hint & SO_FILT_HINT_RESUME) ||
            (so->so_flags & SOF_SUSPENDED) == 0) {
                kn->kn_fflags &= ~(NOTE_SUSPEND | NOTE_RESUME);

                /* If suspend event was delivered before, reset it */
                kn->kn_hookid &= ~NOTE_SUSPEND;

                kn->kn_fflags |= NOTE_RESUME;
                level_trigger |= NOTE_RESUME;
        }

        if (so->so_error != 0) {
                ret = 1;
                kn->kn_data = so->so_error;
                kn->kn_flags |= EV_EOF;
        } else {
                get_sockev_state(so, (u_int32_t *)&(kn->kn_data));
        }

        /* Reset any events that are not requested on this knote */
        kn->kn_fflags &= (kn->kn_sfflags & EVFILT_SOCK_ALL_MASK);
        level_trigger &= (kn->kn_sfflags & EVFILT_SOCK_ALL_MASK);

        /* Find the level triggerred events that are already delivered */
        level_trigger &= kn->kn_hookid;
        level_trigger &= EVFILT_SOCK_LEVEL_TRIGGER_MASK;

        /* Do not deliver level triggerred events more than once */
        if ((kn->kn_fflags & ~level_trigger) != 0)
                ret = 1;

        if (locked)
                socket_unlock(so, 1);

        return (ret);
}

static void
filt_socktouch(struct knote *kn, struct kevent_internal_s *kev, long type)
{
#pragma unused(kev)
        switch (type) {
        case EVENT_REGISTER:
        {
                uint32_t changed_flags;
                changed_flags = (kn->kn_sfflags ^ kn->kn_hookid);

                /*
                 * Since we keep track of events that are already
                 * delivered, if any of those events are not requested
                 * anymore the state related to them can be reset
                 */
                kn->kn_hookid &=
                    ~(changed_flags & EVFILT_SOCK_LEVEL_TRIGGER_MASK);
                break;
        }
        case EVENT_PROCESS:
                /*
                 * Store the state of the events being delivered. This
                 * state can be used to deliver level triggered events
                 * ateast once and still avoid waking up the application
                 * multiple times as long as the event is active.
                 */
                if (kn->kn_fflags != 0)
                        kn->kn_hookid |= (kn->kn_fflags &
                                EVFILT_SOCK_LEVEL_TRIGGER_MASK);

                /*
                 * NOTE_RESUME and NOTE_SUSPEND are an exception, deliver
                 * only one of them and remember the last one that was
                 * delivered last
                 */
                if (kn->kn_fflags & NOTE_SUSPEND)
                        kn->kn_hookid &= ~NOTE_RESUME;
                if (kn->kn_fflags & NOTE_RESUME)
                        kn->kn_hookid &= ~NOTE_SUSPEND;
                break;
        default:
                break;
        }
}

void
get_sockev_state(struct socket *so, u_int32_t *statep)
{
        u_int32_t state = *(statep);

        if (so->so_state & SS_ISCONNECTED)
                state |= SOCKEV_CONNECTED;
        else
                state &= ~(SOCKEV_CONNECTED);
        state |= ((so->so_state & SS_ISDISCONNECTED) ? SOCKEV_DISCONNECTED : 0);
        *(statep) = state;
}

#define SO_LOCK_HISTORY_STR_LEN \
        (2 * SO_LCKDBG_MAX * (2 + (2 * sizeof (void *)) + 1) + 1)

__private_extern__ const char *
solockhistory_nr(struct socket *so)
{
        size_t n = 0;
        int i;
        static char lock_history_str[SO_LOCK_HISTORY_STR_LEN];

        bzero(lock_history_str, sizeof (lock_history_str));
        for (i = SO_LCKDBG_MAX - 1; i >= 0; i--) {
                n += snprintf(lock_history_str + n,
                    SO_LOCK_HISTORY_STR_LEN - n, "%p:%p ",
                    so->lock_lr[(so->next_lock_lr + i) % SO_LCKDBG_MAX],
                    so->unlock_lr[(so->next_unlock_lr + i) % SO_LCKDBG_MAX]);
        }
        return (lock_history_str);
}

int
socket_lock(struct socket *so, int refcount)
{
        int error = 0;
        void *lr_saved;

        lr_saved = __builtin_return_address(0);

        if (so->so_proto->pr_lock) {
                error = (*so->so_proto->pr_lock)(so, refcount, lr_saved);
        } else {
#ifdef MORE_LOCKING_DEBUG
                lck_mtx_assert(so->so_proto->pr_domain->dom_mtx,
                    LCK_MTX_ASSERT_NOTOWNED);
#endif
                lck_mtx_lock(so->so_proto->pr_domain->dom_mtx);
                if (refcount)
                        so->so_usecount++;
                so->lock_lr[so->next_lock_lr] = lr_saved;
                so->next_lock_lr = (so->next_lock_lr+1) % SO_LCKDBG_MAX;
        }

        return (error);
}

int
socket_unlock(struct socket *so, int refcount)
{
        int error = 0;
        void *lr_saved;
        lck_mtx_t *mutex_held;

        lr_saved = __builtin_return_address(0);

        if (so->so_proto == NULL) {
                panic("%s: null so_proto so=%p\n", __func__, so);
                /* NOTREACHED */
        }

        if (so && so->so_proto->pr_unlock) {
                error = (*so->so_proto->pr_unlock)(so, refcount, lr_saved);
        } else {
                mutex_held = so->so_proto->pr_domain->dom_mtx;
#ifdef MORE_LOCKING_DEBUG
                lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);
#endif
                so->unlock_lr[so->next_unlock_lr] = lr_saved;
                so->next_unlock_lr = (so->next_unlock_lr+1) % SO_LCKDBG_MAX;

                if (refcount) {
                        if (so->so_usecount <= 0) {
                                panic("%s: bad refcount=%d so=%p (%d, %d, %d) "
                                    "lrh=%s", __func__, so->so_usecount, so,
                                    SOCK_DOM(so), so->so_type,
                                    SOCK_PROTO(so), solockhistory_nr(so));
                                /* NOTREACHED */
                        }

                        so->so_usecount--;
                        if (so->so_usecount == 0)
                                sofreelastref(so, 1);
                }
                lck_mtx_unlock(mutex_held);
        }

        return (error);
}

/* Called with socket locked, will unlock socket */
void
sofree(struct socket *so)
{
        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);

        sofreelastref(so, 0);
}

void
soreference(struct socket *so)
{
        socket_lock(so, 1);     /* locks & take one reference on socket */
        socket_unlock(so, 0);   /* unlock only */
}

void
sodereference(struct socket *so)
{
        socket_lock(so, 0);
        socket_unlock(so, 1);
}

/*
 * Set or clear SOF_MULTIPAGES on the socket to enable or disable the
 * possibility of using jumbo clusters.  Caller must ensure to hold
 * the socket lock.
 */
void
somultipages(struct socket *so, boolean_t set)
{
        if (set)
                so->so_flags |= SOF_MULTIPAGES;
        else
                so->so_flags &= ~SOF_MULTIPAGES;
}

void
soif2kcl(struct socket *so, boolean_t set)
{
        if (set)
                so->so_flags1 |= SOF1_IF_2KCL;
        else
                so->so_flags1 &= ~SOF1_IF_2KCL;
}

int
so_isdstlocal(struct socket *so) {

        struct inpcb *inp = (struct inpcb *)so->so_pcb;

        if (SOCK_DOM(so) == PF_INET)
                return (inaddr_local(inp->inp_faddr));
        else if (SOCK_DOM(so) == PF_INET6)
                return (in6addr_local(&inp->in6p_faddr));

        return (0);
}

int
sosetdefunct(struct proc *p, struct socket *so, int level, boolean_t noforce)
{
        struct sockbuf *rcv, *snd;
        int err = 0, defunct;

        rcv = &so->so_rcv;
        snd = &so->so_snd;

        defunct = (so->so_flags & SOF_DEFUNCT);
        if (defunct) {
                if (!(snd->sb_flags & rcv->sb_flags & SB_DROP)) {
                        panic("%s: SB_DROP not set", __func__);
                        /* NOTREACHED */
                }
                goto done;
        }

        if (so->so_flags & SOF_NODEFUNCT) {
                if (noforce) {
                        err = EOPNOTSUPP;
                        SODEFUNCTLOG(("%s[%d]: (target pid %d level %d) "
                            "so 0x%llx [%d,%d] is not eligible for defunct "
                            "(%d)\n", __func__, proc_selfpid(), proc_pid(p),
                            level, (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                            SOCK_DOM(so), SOCK_TYPE(so), err));
                        return (err);
                }
                so->so_flags &= ~SOF_NODEFUNCT;
                SODEFUNCTLOG(("%s[%d]: (target pid %d level %d) so 0x%llx "
                    "[%d,%d] defunct by force\n", __func__, proc_selfpid(),
                    proc_pid(p), level, (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so)));
        } else if (so->so_flags1 & SOF1_EXTEND_BK_IDLE_WANTED) {
                struct inpcb *inp = (struct inpcb *)so->so_pcb;
                struct ifnet *ifp = inp->inp_last_outifp;

                if (ifp && IFNET_IS_CELLULAR(ifp)) {
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_nocell);
                } else if (so->so_flags & SOF_DELEGATED) {
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_nodlgtd);
                } else if (soextbkidlestat.so_xbkidle_time == 0) {
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_notime);
                } else if (noforce) {
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_active);
                
                        so->so_flags1 |= SOF1_EXTEND_BK_IDLE_INPROG;
                        so->so_extended_bk_start = net_uptime();
                        OSBitOrAtomic(P_LXBKIDLEINPROG, &p->p_ladvflag);
                        
                        inpcb_timer_sched(inp->inp_pcbinfo, INPCB_TIMER_LAZY);
                        
                        err = EOPNOTSUPP;
                        SODEFUNCTLOG(("%s[%d]: (target pid %d level %d) "
                            "extend bk idle "
                            "so 0x%llx rcv hw %d cc %d\n",
                            __func__, proc_selfpid(), proc_pid(p),
                            level, (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                            so->so_rcv.sb_hiwat, so->so_rcv.sb_cc));
                        return (err);
                } else {
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_forced);
                }
        }

        so->so_flags |= SOF_DEFUNCT;

        /* Prevent further data from being appended to the socket buffers */
        snd->sb_flags |= SB_DROP;
        rcv->sb_flags |= SB_DROP;

        /* Flush any existing data in the socket buffers */
        if (rcv->sb_cc != 0) {
                rcv->sb_flags &= ~SB_SEL;
                selthreadclear(&rcv->sb_sel);
                sbrelease(rcv);
        }
        if (snd->sb_cc != 0) {
                snd->sb_flags &= ~SB_SEL;
                selthreadclear(&snd->sb_sel);
                sbrelease(snd);
        }

done:
        SODEFUNCTLOG(("%s[%d]: (target pid %d level %d) so 0x%llx [%d,%d] %s "
            "defunct%s\n", __func__, proc_selfpid(), proc_pid(p), level,
            (uint64_t)DEBUG_KERNEL_ADDRPERM(so), SOCK_DOM(so), SOCK_TYPE(so),
            defunct ? "is already" : "marked as",
            (so->so_flags1 & SOF1_EXTEND_BK_IDLE_WANTED) ? " extbkidle" : ""));

        return (err);
}

int
sodefunct(struct proc *p, struct socket *so, int level)
{
        struct sockbuf *rcv, *snd;

        if (!(so->so_flags & SOF_DEFUNCT)) {
                panic("%s improperly called", __func__);
                /* NOTREACHED */
        }
        if (so->so_state & SS_DEFUNCT)
                goto done;

        rcv = &so->so_rcv;
        snd = &so->so_snd;

        if (SOCK_DOM(so) == PF_INET || SOCK_DOM(so) == PF_INET6) {
                char s[MAX_IPv6_STR_LEN];
                char d[MAX_IPv6_STR_LEN];
                struct inpcb *inp = sotoinpcb(so);

                SODEFUNCTLOG(("%s[%d]: (target pid %d level %d) so 0x%llx [%s "
                    "%s:%d -> %s:%d] is now defunct [rcv_si 0x%x, snd_si 0x%x, "
                    "rcv_fl 0x%x, snd_fl 0x%x]\n", __func__, proc_selfpid(),
                    proc_pid(p), level, (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    (SOCK_TYPE(so) == SOCK_STREAM) ? "TCP" : "UDP",
                    inet_ntop(SOCK_DOM(so), ((SOCK_DOM(so) == PF_INET) ?
                    (void *)&inp->inp_laddr.s_addr : (void *)&inp->in6p_laddr),
                    s, sizeof (s)), ntohs(inp->in6p_lport),
                    inet_ntop(SOCK_DOM(so), (SOCK_DOM(so) == PF_INET) ?
                    (void *)&inp->inp_faddr.s_addr : (void *)&inp->in6p_faddr,
                    d, sizeof (d)), ntohs(inp->in6p_fport),
                    (uint32_t)rcv->sb_sel.si_flags,
                    (uint32_t)snd->sb_sel.si_flags,
                    rcv->sb_flags, snd->sb_flags));
        } else {
                SODEFUNCTLOG(("%s[%d]: (target pid %d level %d) so 0x%llx "
                    "[%d,%d] is now defunct [rcv_si 0x%x, snd_si 0x%x, "
                    "rcv_fl 0x%x, snd_fl 0x%x]\n", __func__, proc_selfpid(),
                    proc_pid(p), level, (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so), (uint32_t)rcv->sb_sel.si_flags,
                    (uint32_t)snd->sb_sel.si_flags, rcv->sb_flags,
                    snd->sb_flags));
        }

        /*
         * Unwedge threads blocked on sbwait() and sb_lock().
         */
        sbwakeup(rcv);
        sbwakeup(snd);

        so->so_flags1 |= SOF1_DEFUNCTINPROG;
        if (rcv->sb_flags & SB_LOCK)
                sbunlock(rcv, TRUE);    /* keep socket locked */
        if (snd->sb_flags & SB_LOCK)
                sbunlock(snd, TRUE);    /* keep socket locked */

        /*
         * Flush the buffers and disconnect.  We explicitly call shutdown
         * on both data directions to ensure that SS_CANT{RCV,SEND}MORE
         * states are set for the socket.  This would also flush out data
         * hanging off the receive list of this socket.
         */
        (void) soshutdownlock_final(so, SHUT_RD);
        (void) soshutdownlock_final(so, SHUT_WR);
        (void) sodisconnectlocked(so);

        /*
         * Explicitly handle connectionless-protocol disconnection
         * and release any remaining data in the socket buffers.
         */
        if (!(so->so_flags & SS_ISDISCONNECTED))
                (void) soisdisconnected(so);

        if (so->so_error == 0)
                so->so_error = EBADF;

        if (rcv->sb_cc != 0) {
                rcv->sb_flags &= ~SB_SEL;
                selthreadclear(&rcv->sb_sel);
                sbrelease(rcv);
        }
        if (snd->sb_cc != 0) {
                snd->sb_flags &= ~SB_SEL;
                selthreadclear(&snd->sb_sel);
                sbrelease(snd);
        }
        so->so_state |= SS_DEFUNCT;

done:
        return (0);
}

int
soresume(struct proc *p, struct socket *so, int locked)
{
        if (locked == 0)
                socket_lock(so, 1);

        if (so->so_flags1 & SOF1_EXTEND_BK_IDLE_INPROG) {
                SODEFUNCTLOG(("%s[%d]: )target pid %d) so 0x%llx [%d,%d] "
                    "resumed from bk idle\n",
                    __func__, proc_selfpid(), proc_pid(p),
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so)));

                so->so_flags1 &= ~SOF1_EXTEND_BK_IDLE_INPROG;
                so->so_extended_bk_start = 0;
                OSBitAndAtomic(~P_LXBKIDLEINPROG, &p->p_ladvflag);

                OSIncrementAtomic(&soextbkidlestat.so_xbkidle_resumed);
                OSDecrementAtomic(&soextbkidlestat.so_xbkidle_active);
                VERIFY(soextbkidlestat.so_xbkidle_active >= 0);
        }
        if (locked == 0)
                socket_unlock(so, 1);

        return (0);
}

/*
 * Does not attempt to account for sockets that are delegated from
 * the current process
 */
int
so_set_extended_bk_idle(struct socket *so, int optval)
{
        int error = 0;

        if ((SOCK_DOM(so) != PF_INET && SOCK_DOM(so) != PF_INET6) ||
            SOCK_PROTO(so) != IPPROTO_TCP) {
                OSDecrementAtomic(&soextbkidlestat.so_xbkidle_notsupp);
                error = EOPNOTSUPP;
        } else if (optval == 0) {
                so->so_flags1 &= ~SOF1_EXTEND_BK_IDLE_WANTED;

                soresume(current_proc(), so, 1);
        } else {
                struct proc *p = current_proc();
                int i;
                struct filedesc *fdp;
                int count = 0;

                proc_fdlock(p);

                fdp = p->p_fd;
                for (i = 0; i < fdp->fd_nfiles; i++) {
                        struct fileproc *fp = fdp->fd_ofiles[i];
                        struct socket *so2;

                        if (fp == NULL ||
                            (fdp->fd_ofileflags[i] & UF_RESERVED) != 0 ||
                            FILEGLOB_DTYPE(fp->f_fglob) != DTYPE_SOCKET)
                                continue;

                        so2 = (struct socket *)fp->f_fglob->fg_data;
                        if (so != so2 &&
                            so2->so_flags1 & SOF1_EXTEND_BK_IDLE_WANTED)
                                count++;
                        if (count >= soextbkidlestat.so_xbkidle_maxperproc)
                                break;
                }
                if (count >= soextbkidlestat.so_xbkidle_maxperproc) {
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_toomany);
                        error = EBUSY;
                } else if (so->so_flags & SOF_DELEGATED) {
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_nodlgtd);
                        error = EBUSY;
                } else {
                        so->so_flags1 |= SOF1_EXTEND_BK_IDLE_WANTED;
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_wantok);
                }
                SODEFUNCTLOG(("%s[%d]: so 0x%llx [%d,%d] "
                    "%s marked for extended bk idle\n",
                    __func__, proc_selfpid(),
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so),
                    (so->so_flags1 & SOF1_EXTEND_BK_IDLE_WANTED) ?
                    "is" : "not"));

                proc_fdunlock(p);
        }

        return (error);
}

static void
so_stop_extended_bk_idle(struct socket *so)
{
        so->so_flags1 &= ~SOF1_EXTEND_BK_IDLE_INPROG;
        so->so_extended_bk_start = 0;

        OSDecrementAtomic(&soextbkidlestat.so_xbkidle_active);
        VERIFY(soextbkidlestat.so_xbkidle_active >= 0);
        /*
         * Force defunct
         */
        sosetdefunct(current_proc(), so,
            SHUTDOWN_SOCKET_LEVEL_DISCONNECT_INTERNAL, FALSE);
        if (so->so_flags & SOF_DEFUNCT) {
                sodefunct(current_proc(), so,
                    SHUTDOWN_SOCKET_LEVEL_DISCONNECT_INTERNAL);
        }
}

void
so_drain_extended_bk_idle(struct socket *so)
{
        if (so && (so->so_flags1 & SOF1_EXTEND_BK_IDLE_INPROG)) {
                /*
                 * Only penalize sockets that have outstanding data
                 */
                if (so->so_rcv.sb_cc || so->so_snd.sb_cc) {
                        so_stop_extended_bk_idle(so);

                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_drained);
                }
        }
}

/*
 * Return values tells if socket is still in extended background idle
 */
int
so_check_extended_bk_idle_time(struct socket *so)
{
        int ret = 1;

        if ((so->so_flags1 & SOF1_EXTEND_BK_IDLE_INPROG)) {
                SODEFUNCTLOG(("%s[%d]: so 0x%llx [%d,%d]\n",
                    __func__, proc_selfpid(),
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so)));
                if (net_uptime() - so->so_extended_bk_start >
                    soextbkidlestat.so_xbkidle_time) {
                        so_stop_extended_bk_idle(so);

                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_expired);

                        ret = 0;
                } else {
                        struct inpcb *inp = (struct inpcb *)so->so_pcb;

                        inpcb_timer_sched(inp->inp_pcbinfo, INPCB_TIMER_LAZY);
                        OSIncrementAtomic(&soextbkidlestat.so_xbkidle_resched);
                }
        }
        
        return (ret);
}

void
resume_proc_sockets(proc_t p)
{
        if (p->p_ladvflag & P_LXBKIDLEINPROG) {
                struct filedesc *fdp;
                int i;

                proc_fdlock(p);
                fdp = p->p_fd;
                for (i = 0; i < fdp->fd_nfiles; i++) {
                        struct fileproc *fp;
                        struct socket *so;

                        fp = fdp->fd_ofiles[i];
                        if (fp == NULL || 
                            (fdp->fd_ofileflags[i] & UF_RESERVED) != 0 ||
                            FILEGLOB_DTYPE(fp->f_fglob) != DTYPE_SOCKET)
                                continue;

                        so = (struct socket *)fp->f_fglob->fg_data;
                        (void) soresume(p, so, 0);
                }
                proc_fdunlock(p);

                OSBitAndAtomic(~P_LXBKIDLEINPROG, &p->p_ladvflag);
        }
}

__private_extern__ int
so_set_recv_anyif(struct socket *so, int optval)
{
        int ret = 0;

#if INET6
        if (SOCK_DOM(so) == PF_INET || SOCK_DOM(so) == PF_INET6) {
#else
        if (SOCK_DOM(so) == PF_INET) {
#endif /* !INET6 */
                if (optval)
                        sotoinpcb(so)->inp_flags |= INP_RECV_ANYIF;
                else
                        sotoinpcb(so)->inp_flags &= ~INP_RECV_ANYIF;
        }

        return (ret);
}

__private_extern__ int
so_get_recv_anyif(struct socket *so)
{
        int ret = 0;

#if INET6
        if (SOCK_DOM(so) == PF_INET || SOCK_DOM(so) == PF_INET6) {
#else
        if (SOCK_DOM(so) == PF_INET) {
#endif /* !INET6 */
                ret = (sotoinpcb(so)->inp_flags & INP_RECV_ANYIF) ? 1 : 0;
        }

        return (ret);
}

int
so_set_restrictions(struct socket *so, uint32_t vals)
{
        int nocell_old, nocell_new;
        int noexpensive_old, noexpensive_new;

        /*
         * Deny-type restrictions are trapdoors; once set they cannot be
         * unset for the lifetime of the socket.  This allows them to be
         * issued by a framework on behalf of the application without
         * having to worry that they can be undone.
         *
         * Note here that socket-level restrictions overrides any protocol
         * level restrictions.  For instance, SO_RESTRICT_DENY_CELLULAR
         * socket restriction issued on the socket has a higher precendence
         * than INP_NO_IFT_CELLULAR.  The latter is affected by the UUID
         * policy PROC_UUID_NO_CELLULAR for unrestricted sockets only,
         * i.e. when SO_RESTRICT_DENY_CELLULAR has not been issued.
         */
        nocell_old = (so->so_restrictions & SO_RESTRICT_DENY_CELLULAR);
        noexpensive_old = (so->so_restrictions & SO_RESTRICT_DENY_EXPENSIVE);
        so->so_restrictions |= (vals & (SO_RESTRICT_DENY_IN |
            SO_RESTRICT_DENY_OUT | SO_RESTRICT_DENY_CELLULAR |
            SO_RESTRICT_DENY_EXPENSIVE));
        nocell_new = (so->so_restrictions & SO_RESTRICT_DENY_CELLULAR);
        noexpensive_new = (so->so_restrictions & SO_RESTRICT_DENY_EXPENSIVE);

        /* we can only set, not clear restrictions */
        if ((nocell_new - nocell_old) == 0 &&
            (noexpensive_new - noexpensive_old) == 0)
                return (0);
#if INET6
        if (SOCK_DOM(so) == PF_INET || SOCK_DOM(so) == PF_INET6) {
#else
        if (SOCK_DOM(so) == PF_INET) {
#endif /* !INET6 */
                if (nocell_new - nocell_old != 0) {
                        /*
                         * if deny cellular is now set, do what's needed
                         * for INPCB
                         */
                        inp_set_nocellular(sotoinpcb(so));
                }
                if (noexpensive_new - noexpensive_old != 0) {
                        inp_set_noexpensive(sotoinpcb(so));
                }
        }

        return (0);
}

uint32_t
so_get_restrictions(struct socket *so)
{
        return (so->so_restrictions & (SO_RESTRICT_DENY_IN |
            SO_RESTRICT_DENY_OUT |
            SO_RESTRICT_DENY_CELLULAR | SO_RESTRICT_DENY_EXPENSIVE));
}

struct sockaddr_entry *
sockaddrentry_alloc(int how)
{
        struct sockaddr_entry *se;

        se = (how == M_WAITOK) ? zalloc(se_zone) : zalloc_noblock(se_zone);
        if (se != NULL)
                bzero(se, se_zone_size);

        return (se);
}

void
sockaddrentry_free(struct sockaddr_entry *se)
{
        if (se->se_addr != NULL) {
                FREE(se->se_addr, M_SONAME);
                se->se_addr = NULL;
        }
        zfree(se_zone, se);
}

struct sockaddr_entry *
sockaddrentry_dup(const struct sockaddr_entry *src_se, int how)
{
        struct sockaddr_entry *dst_se;

        dst_se = sockaddrentry_alloc(how);
        if (dst_se != NULL) {
                int len = src_se->se_addr->sa_len;

                MALLOC(dst_se->se_addr, struct sockaddr *,
                    len, M_SONAME, how | M_ZERO);
                if (dst_se->se_addr != NULL) {
                        bcopy(src_se->se_addr, dst_se->se_addr, len);
                } else {
                        sockaddrentry_free(dst_se);
                        dst_se = NULL;
                }
        }

        return (dst_se);
}

struct sockaddr_list *
sockaddrlist_alloc(int how)
{
        struct sockaddr_list *sl;

        sl = (how == M_WAITOK) ? zalloc(sl_zone) : zalloc_noblock(sl_zone);
        if (sl != NULL) {
                bzero(sl, sl_zone_size);
                TAILQ_INIT(&sl->sl_head);
        }
        return (sl);
}

void
sockaddrlist_free(struct sockaddr_list *sl)
{
        struct sockaddr_entry *se, *tse;

        TAILQ_FOREACH_SAFE(se, &sl->sl_head, se_link, tse) {
                sockaddrlist_remove(sl, se);
                sockaddrentry_free(se);
        }
        VERIFY(sl->sl_cnt == 0 && TAILQ_EMPTY(&sl->sl_head));
        zfree(sl_zone, sl);
}

void
sockaddrlist_insert(struct sockaddr_list *sl, struct sockaddr_entry *se)
{
        VERIFY(!(se->se_flags & SEF_ATTACHED));
        se->se_flags |= SEF_ATTACHED;
        TAILQ_INSERT_TAIL(&sl->sl_head, se, se_link);
        sl->sl_cnt++;
        VERIFY(sl->sl_cnt != 0);
}

void
sockaddrlist_remove(struct sockaddr_list *sl, struct sockaddr_entry *se)
{
        VERIFY(se->se_flags & SEF_ATTACHED);
        se->se_flags &= ~SEF_ATTACHED;
        VERIFY(sl->sl_cnt != 0);
        sl->sl_cnt--;
        TAILQ_REMOVE(&sl->sl_head, se, se_link);
}

struct sockaddr_list *
sockaddrlist_dup(const struct sockaddr_list *src_sl, int how)
{
        struct sockaddr_entry *src_se, *tse;
        struct sockaddr_list *dst_sl;

        dst_sl = sockaddrlist_alloc(how);
        if (dst_sl == NULL)
                return (NULL);

        TAILQ_FOREACH_SAFE(src_se, &src_sl->sl_head, se_link, tse) {
                struct sockaddr_entry *dst_se;

                if (src_se->se_addr == NULL)
                        continue;

                dst_se = sockaddrentry_dup(src_se, how);
                if (dst_se == NULL) {
                        sockaddrlist_free(dst_sl);
                        return (NULL);
                }

                sockaddrlist_insert(dst_sl, dst_se);
        }
        VERIFY(src_sl->sl_cnt == dst_sl->sl_cnt);

        return (dst_sl);
}

int
so_set_effective_pid(struct socket *so, int epid, struct proc *p)
{
        struct proc *ep = PROC_NULL;
        int error = 0;

        /* pid 0 is reserved for kernel */
        if (epid == 0) {
                error = EINVAL;
                goto done;
        }

        /*
         * If this is an in-kernel socket, prevent its delegate
         * association from changing unless the socket option is
         * coming from within the kernel itself.
         */
        if (so->last_pid == 0 && p != kernproc) {
                error = EACCES;
                goto done;
        }

        /*
         * If this is issued by a process that's recorded as the
         * real owner of the socket, or if the pid is the same as
         * the process's own pid, then proceed.  Otherwise ensure
         * that the issuing process has the necessary privileges.
         */
        if (epid != so->last_pid || epid != proc_pid(p)) {
                if ((error = priv_check_cred(kauth_cred_get(),
                    PRIV_NET_PRIVILEGED_SOCKET_DELEGATE, 0))) {
                        error = EACCES;
                        goto done;
                }
        }

        /* Find the process that corresponds to the effective pid */
        if ((ep = proc_find(epid)) == PROC_NULL) {
                error = ESRCH;
                goto done;
        }

        /*
         * If a process tries to delegate the socket to itself, then
         * there's really nothing to do; treat it as a way for the
         * delegate association to be cleared.  Note that we check
         * the passed-in proc rather than calling proc_selfpid(),
         * as we need to check the process issuing the socket option
         * which could be kernproc.  Given that we don't allow 0 for
         * effective pid, it means that a delegated in-kernel socket
         * stays delegated during its lifetime (which is probably OK.)
         */
        if (epid == proc_pid(p)) {
                so->so_flags &= ~SOF_DELEGATED;
                so->e_upid = 0;
                so->e_pid = 0;
                uuid_clear(so->e_uuid);
        } else {
                so->so_flags |= SOF_DELEGATED;
                so->e_upid = proc_uniqueid(ep);
                so->e_pid = proc_pid(ep);
                proc_getexecutableuuid(ep, so->e_uuid, sizeof (so->e_uuid));
        }
done:
        if (error == 0 && net_io_policy_log) {
                uuid_string_t buf;

                uuid_unparse(so->e_uuid, buf);
                log(LOG_DEBUG, "%s[%s,%d]: so 0x%llx [%d,%d] epid %d (%s) "
                    "euuid %s%s\n", __func__, proc_name_address(p),
                    proc_pid(p), (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so),
                    so->e_pid, proc_name_address(ep), buf,
                    ((so->so_flags & SOF_DELEGATED) ? " [delegated]" : ""));
        } else if (error != 0 && net_io_policy_log) {
                log(LOG_ERR, "%s[%s,%d]: so 0x%llx [%d,%d] epid %d (%s) "
                    "ERROR (%d)\n", __func__, proc_name_address(p),
                    proc_pid(p), (uint64_t)DEBUG_KERNEL_ADDRPERM(so),
                    SOCK_DOM(so), SOCK_TYPE(so),
                    epid, (ep == PROC_NULL) ? "PROC_NULL" :
                    proc_name_address(ep), error);
        }

        /* Update this socket's policy upon success */
        if (error == 0) {
                so->so_policy_gencnt *= -1;
                so_update_policy(so);
#if NECP
                so_update_necp_policy(so, NULL, NULL);
#endif /* NECP */
        }

        if (ep != PROC_NULL)
                proc_rele(ep);

        return (error);
}

int
so_set_effective_uuid(struct socket *so, uuid_t euuid, struct proc *p)
{
        uuid_string_t buf;
        uuid_t uuid;
        int error = 0;

        /* UUID must not be all-zeroes (reserved for kernel) */
        if (uuid_is_null(euuid)) {
                error = EINVAL;
                goto done;
        }

        /*
         * If this is an in-kernel socket, prevent its delegate
         * association from changing unless the socket option is
         * coming from within the kernel itself.
         */
        if (so->last_pid == 0 && p != kernproc) {
                error = EACCES;
                goto done;
        }

        /* Get the UUID of the issuing process */
        proc_getexecutableuuid(p, uuid, sizeof (uuid));

        /*
         * If this is issued by a process that's recorded as the
         * real owner of the socket, or if the uuid is the same as
         * the process's own uuid, then proceed.  Otherwise ensure
         * that the issuing process has the necessary privileges.
         */
        if (uuid_compare(euuid, so->last_uuid) != 0 ||
            uuid_compare(euuid, uuid) != 0) {
                if ((error = priv_check_cred(kauth_cred_get(),
                    PRIV_NET_PRIVILEGED_SOCKET_DELEGATE, 0))) {
                        error = EACCES;
                        goto done;
                }
        }

        /*
         * If a process tries to delegate the socket to itself, then
         * there's really nothing to do; treat it as a way for the
         * delegate association to be cleared.  Note that we check
         * the uuid of the passed-in proc rather than that of the
         * current process, as we need to check the process issuing
         * the socket option which could be kernproc itself.  Given
         * that we don't allow 0 for effective uuid, it means that
         * a delegated in-kernel socket stays delegated during its
         * lifetime (which is okay.)
         */
        if (uuid_compare(euuid, uuid) == 0) {
                so->so_flags &= ~SOF_DELEGATED;
                so->e_upid = 0;
                so->e_pid = 0;
                uuid_clear(so->e_uuid);
        } else {
                so->so_flags |= SOF_DELEGATED;
                /*
                 * Unlike so_set_effective_pid(), we only have the UUID
                 * here and the process ID is not known.  Inherit the
                 * real {pid,upid} of the socket.
                 */
                so->e_upid = so->last_upid;
                so->e_pid = so->last_pid;
                uuid_copy(so->e_uuid, euuid);
        }

done:
        if (error == 0 && net_io_policy_log) {
                uuid_unparse(so->e_uuid, buf);
                log(LOG_DEBUG, "%s[%s,%d]: so 0x%llx [%d,%d] epid %d "
                    "euuid %s%s\n", __func__, proc_name_address(p), proc_pid(p),
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so), SOCK_DOM(so),
                    SOCK_TYPE(so), so->e_pid, buf,
                    ((so->so_flags & SOF_DELEGATED) ? " [delegated]" : ""));
        } else if (error != 0 && net_io_policy_log) {
                uuid_unparse(euuid, buf);
                log(LOG_DEBUG, "%s[%s,%d]: so 0x%llx [%d,%d] euuid %s "
                    "ERROR (%d)\n", __func__, proc_name_address(p), proc_pid(p),
                    (uint64_t)DEBUG_KERNEL_ADDRPERM(so), SOCK_DOM(so),
                    SOCK_TYPE(so), buf, error);
        }

        /* Update this socket's policy upon success */
        if (error == 0) {
                so->so_policy_gencnt *= -1;
                so_update_policy(so);
#if NECP
                so_update_necp_policy(so, NULL, NULL);
#endif /* NECP */
        }

        return (error);
}

void
netpolicy_post_msg(uint32_t ev_code, struct netpolicy_event_data *ev_data,
    uint32_t ev_datalen)
{
        struct kev_msg ev_msg;

        /*
         * A netpolicy event always starts with a netpolicy_event_data
         * structure, but the caller can provide for a longer event
         * structure to post, depending on the event code.
         */
        VERIFY(ev_data != NULL && ev_datalen >= sizeof (*ev_data));

        bzero(&ev_msg, sizeof (ev_msg));
        ev_msg.vendor_code      = KEV_VENDOR_APPLE;
        ev_msg.kev_class        = KEV_NETWORK_CLASS;
        ev_msg.kev_subclass     = KEV_NETPOLICY_SUBCLASS;
        ev_msg.event_code       = ev_code;

        ev_msg.dv[0].data_ptr   = ev_data;
        ev_msg.dv[0].data_length = ev_datalen;

        kev_post_msg(&ev_msg);
}

void
socket_post_kev_msg(uint32_t ev_code,
    struct kev_socket_event_data *ev_data,
    uint32_t ev_datalen)
{
        struct kev_msg ev_msg;

        bzero(&ev_msg, sizeof(ev_msg));
        ev_msg.vendor_code = KEV_VENDOR_APPLE;
        ev_msg.kev_class = KEV_NETWORK_CLASS;
        ev_msg.kev_subclass = KEV_SOCKET_SUBCLASS;
        ev_msg.event_code = ev_code;

        ev_msg.dv[0].data_ptr = ev_data;
        ev_msg.dv[0]. data_length = ev_datalen;

        kev_post_msg(&ev_msg);
}

void
socket_post_kev_msg_closed(struct socket *so)
{
        struct kev_socket_closed ev;
        struct sockaddr *socksa = NULL, *peersa = NULL;
        int err;
        bzero(&ev, sizeof(ev));
        err = (*so->so_proto->pr_usrreqs->pru_sockaddr)(so, &socksa);
        if (err == 0) {
                err = (*so->so_proto->pr_usrreqs->pru_peeraddr)(so,
                    &peersa);
                if (err == 0) {
                        memcpy(&ev.ev_data.kev_sockname, socksa,
                            min(socksa->sa_len,
                            sizeof (ev.ev_data.kev_sockname)));
                        memcpy(&ev.ev_data.kev_peername, peersa,
                            min(peersa->sa_len,
                            sizeof (ev.ev_data.kev_peername)));
                        socket_post_kev_msg(KEV_SOCKET_CLOSED,
                            &ev.ev_data, sizeof (ev));
                }
        }
        if (socksa != NULL)
                FREE(socksa, M_SONAME);
        if (peersa != NULL)
                FREE(peersa, M_SONAME);
}