xnu-2422.115.4.tar.gz

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

/*
 * Copyright (c) 1998-2013 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)uipc_socket2.c      8.1 (Berkeley) 6/10/93
 */
/*
 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */

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

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

#include <mach/vm_param.h>

/* TODO: this should be in a header file somewhere */
extern void postevent(struct socket *, struct sockbuf *, int);

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

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

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

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

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

static  u_int32_t sb_efficiency = 8;    /* parameter for sbreserve() */
__private_extern__ int32_t total_sbmb_cnt = 0;

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

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

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

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

        sflt_notify(so, sock_evt_connecting, NULL);
}

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

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

        sflt_notify(so, sock_evt_connected, NULL);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

        return (sonewconn_internal(head, connstatus));
}

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

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

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

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

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

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

        lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

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

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

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

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

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

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

        return (error);
}

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

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

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

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

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

                so->so_upcallusecount--;
                /* Tell close that it's safe to proceed */
                if ((so->so_flags & SOF_CLOSEWAIT) &&
                    so->so_upcallusecount == 0)
                        wakeup((caddr_t)&so->so_upcallusecount);
        }
}

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

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

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

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

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

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

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

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

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

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

        SBLASTRECORDCHK(sb, "sbappend 1");

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

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

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

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

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

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

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

        SBLASTMBUFCHK(sb, __func__);

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

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

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

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

        lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

        if (sbchecking == 0)
                return;

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

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

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

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

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

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

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

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

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

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

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

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

        if (sb->sb_flags & SB_RECV) {
                int error = sflt_data_in(sb->sb_so, NULL, &m0, NULL,
                    sock_data_filt_flag_record);
                if (error != 0) {
                        SBLASTRECORDCHK(sb, "sbappendrecord 1");
                        if (error != EJUSTRETURN)
                                m_freem(m0);
                        return (0);
                }
        }

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

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

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

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

        SBLASTRECORDCHK(sb, "sbinsertoob 1");

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

                SBLASTRECORDCHK(sb, "sbinsertoob 2");
                if (error) {
                        if (error != EJUSTRETURN) {
                                m_freem(m0);
                        }
                        return (0);
                }
        }

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

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

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

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

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

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

        SBLASTRECORDCHK(sb, "sbappendadddr 1");

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

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

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

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

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

        if (error_out)
                *error_out = 0;

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

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

        /* Call socket data in filters */
        if ((sb->sb_flags & SB_RECV) != 0) {
                int error;
                error = sflt_data_in(sb->sb_so, asa, &m0, &control, 0);
                SBLASTRECORDCHK(sb, __func__);
                if (error) {
                        if (error != EJUSTRETURN) {
                                if (m0)
                                        m_freem(m0);
                                if (control != NULL && !sb_unix)
                                        m_freem(control);
                                if (error_out)
                                        *error_out = error;
                        }
                        return (0);
                }
        }

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

        return (result);
}

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

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

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

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

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

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

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

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

        if (error_out)
                *error_out = 0;

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

        if (sb->sb_flags & SB_RECV) {
                int error;

                error = sflt_data_in(sb->sb_so, NULL, &m0, &control, 0);
                SBLASTRECORDCHK(sb, __func__);
                if (error) {
                        if (error != EJUSTRETURN) {
                                if (m0)
                                        m_freem(m0);
                                if (control != NULL && !sb_unix)
                                        m_freem(control);
                                if (error_out)
                                        *error_out = error;
                        }
                        return (0);
                }
        }

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

        return (result);
}

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

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

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

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

                if (m_eor->m_next == NULL)
                        break;
        }

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

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

        ret = sbappendrecord(sb, m);
        return (ret);
}

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

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

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

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

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

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

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

        SBLASTMBUFCHK(sb, __func__);

        mptcp_adj_rmap(so, m);

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

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

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

        VERIFY(so->so_msg_state != NULL);

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

        SBLASTMBUFCHK(sb, __func__);

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

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

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

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

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

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

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

        /* Update accounting and the queue tail pointer */

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

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

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

        priq->msgq_tail = m;

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

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

        VERIFY(so->so_msg_state != NULL);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);
#endif

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

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

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

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

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

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

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

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

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

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

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

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

        postevent(0, sb, EV_RWBYTES);

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

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

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

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

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

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

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

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

        m = *mp;

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

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

        return (mp);
}


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        return (0);
}


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

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

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

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

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

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

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

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

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

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

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

        return (space);
}

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

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

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

/* can we write something to so? */

int
sowriteable(struct socket *so)
{
        return ((!so_wait_for_if_feedback(so) &&
            sbspace(&(so)->so_snd) >= (so)->so_snd.sb_lowat &&
            ((so->so_state & SS_ISCONNECTED) ||
            (so->so_proto->pr_flags & PR_CONNREQUIRED) == 0)) ||
            (so->so_state & SS_CANTSENDMORE) ||
            so->so_error);
}

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

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

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

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

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

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

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

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

        if ((sb->sb_flags & SB_LOCK) && !(flags & SBL_WAIT))
                return (EWOULDBLOCK);

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

        while (sb->sb_flags & SB_LOCK) {
                lck_mtx_t *mutex_held;

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

                lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

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

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

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

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

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

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

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

        VERIFY(sb->sb_flags & SB_LOCK);
        sb->sb_flags &= ~SB_LOCK;

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

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

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

                lck_mtx_assert(mutex_held, LCK_MTX_ASSERT_OWNED);

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

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

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

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

        soevupcall(so, hint);

        /* Don't post an event if this a subflow socket */
        if ((hint & SO_FILT_HINT_IFDENIED) && !(so->so_flags & SOF_MP_SUBFLOW))
                soevent_ifdenied(so);
}

void
soevupcall(struct socket *so, u_int32_t hint)
{
        void (*so_event)(struct socket *, void *, uint32_t);

        if ((so_event = so->so_event) != NULL) {
                caddr_t so_eventarg = so->so_eventarg;

                hint &= so->so_eventmask;
                if (hint != 0) {
                        socket_unlock(so, 0);
                        so->so_event(so, so_eventarg, hint);
                        socket_lock(so, 0);
                }
        }
}

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

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

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

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

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

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

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

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



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


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

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

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

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

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

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

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

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

        i = net_io_policy_throttled;

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

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

        net_io_policy_throttled = i;

        return (err);
}

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

SYSCTL_INT(_kern_ipc, OID_AUTO, maxsockets,
        CTLFLAG_RD | CTLFLAG_LOCKED, &maxsockets, 0,
        "Maximum number of sockets avaliable");

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

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

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

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

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

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

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

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

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

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