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[netbsd-mini2440.git] / sys / kern / uipc_socket2.c

/*      $NetBSD: uipc_socket2.c,v 1.105 2009/12/30 18:33:53 elad Exp $  */

/*-
 * Copyright (c) 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * 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. 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      8.2 (Berkeley) 2/14/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uipc_socket2.c,v 1.105 2009/12/30 18:33:53 elad Exp $");

#include "opt_mbuftrace.h"
#include "opt_sb_max.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/file.h>
#include <sys/buf.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/signalvar.h>
#include <sys/kauth.h>
#include <sys/pool.h>
#include <sys/uidinfo.h>

/*
 * Primitive routines for operating on sockets and socket buffers.
 *
 * Locking rules and assumptions:
 *
 * o socket::so_lock can change on the fly.  The low level routines used
 *   to lock sockets are aware of this.  When so_lock is acquired, the
 *   routine locking must check to see if so_lock still points to the
 *   lock that was acquired.  If so_lock has changed in the meantime, the
 *   now irellevant lock that was acquired must be dropped and the lock
 *   operation retried.  Although not proven here, this is completely safe
 *   on a multiprocessor system, even with relaxed memory ordering, given
 *   the next two rules:
 *
 * o In order to mutate so_lock, the lock pointed to by the current value
 *   of so_lock must be held: i.e., the socket must be held locked by the
 *   changing thread.  The thread must issue membar_exit() to prevent
 *   memory accesses being reordered, and can set so_lock to the desired
 *   value.  If the lock pointed to by the new value of so_lock is not
 *   held by the changing thread, the socket must then be considered
 *   unlocked.
 *
 * o If so_lock is mutated, and the previous lock referred to by so_lock
 *   could still be visible to other threads in the system (e.g. via file
 *   descriptor or protocol-internal reference), then the old lock must
 *   remain valid until the socket and/or protocol control block has been
 *   torn down.
 *
 * o If a socket has a non-NULL so_head value (i.e. is in the process of
 *   connecting), then locking the socket must also lock the socket pointed
 *   to by so_head: their lock pointers must match.
 *
 * o If a socket has connections in progress (so_q, so_q0 not empty) then
 *   locking the socket must also lock the sockets attached to both queues.
 *   Again, their lock pointers must match.
 *
 * o Beyond the initial lock assigment in socreate(), assigning locks to
 *   sockets is the responsibility of the individual protocols / protocol
 *   domains.
 */

static pool_cache_t socket_cache;

u_long  sb_max = SB_MAX;        /* maximum socket buffer size */
static u_long sb_max_adj;       /* adjusted sb_max */

/*
 * 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_q0 for connections in progress
 * and so_q for connections already made and awaiting user acceptance.
 * As a protocol is preparing incoming connections, it creates a socket
 * structure queued on so_q0 by calling sonewconn().  When the connection
 * is established, soisconnected() is called, and transfers the
 * socket structure to so_q, making it available to accept().
 *
 * If a socket is closed with sockets on either
 * so_q0 or so_q, 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)
{

        KASSERT(solocked(so));

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

void
soisconnected(struct socket *so)
{
        struct socket   *head;

        head = so->so_head;

        KASSERT(solocked(so));
        KASSERT(head == NULL || solocked2(so, head));

        so->so_state &= ~(SS_ISCONNECTING|SS_ISDISCONNECTING|SS_ISCONFIRMING);
        so->so_state |= SS_ISCONNECTED;
        if (head && so->so_onq == &head->so_q0) {
                if ((so->so_options & SO_ACCEPTFILTER) == 0) {
                        soqremque(so, 0);
                        soqinsque(head, so, 1);
                        sorwakeup(head);
                        cv_broadcast(&head->so_cv);
                } else {
                        so->so_upcall =
                            head->so_accf->so_accept_filter->accf_callback;
                        so->so_upcallarg = head->so_accf->so_accept_filter_arg;
                        so->so_rcv.sb_flags |= SB_UPCALL;
                        so->so_options &= ~SO_ACCEPTFILTER;
                        (*so->so_upcall)(so, so->so_upcallarg,
                                         POLLIN|POLLRDNORM, M_DONTWAIT);
                }
        } else {
                cv_broadcast(&so->so_cv);
                sorwakeup(so);
                sowwakeup(so);
        }
}

void
soisdisconnecting(struct socket *so)
{

        KASSERT(solocked(so));

        so->so_state &= ~SS_ISCONNECTING;
        so->so_state |= (SS_ISDISCONNECTING|SS_CANTRCVMORE|SS_CANTSENDMORE);
        cv_broadcast(&so->so_cv);
        sowwakeup(so);
        sorwakeup(so);
}

void
soisdisconnected(struct socket *so)
{

        KASSERT(solocked(so));

        so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
        so->so_state |= (SS_CANTRCVMORE|SS_CANTSENDMORE|SS_ISDISCONNECTED);
        cv_broadcast(&so->so_cv);
        sowwakeup(so);
        sorwakeup(so);
}

void
soinit2(void)
{

        socket_cache = pool_cache_init(sizeof(struct socket), 0, 0, 0,
            "socket", NULL, IPL_SOFTNET, NULL, NULL, NULL);
}

/*
 * 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, SS_ISCONFIRMING, or SS_ISCONNECTED.
 */
struct socket *
sonewconn(struct socket *head, int connstatus)
{
        struct socket   *so;
        int             soqueue, error;

        KASSERT(connstatus == 0 || connstatus == SS_ISCONFIRMING ||
            connstatus == SS_ISCONNECTED);
        KASSERT(solocked(head));

        if ((head->so_options & SO_ACCEPTFILTER) != 0)
                connstatus = 0;
        soqueue = connstatus ? 1 : 0;
        if (head->so_qlen + head->so_q0len > 3 * head->so_qlimit / 2)
                return NULL;
        so = soget(false);
        if (so == NULL)
                return NULL;
        mutex_obj_hold(head->so_lock);
        so->so_lock = head->so_lock;
        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_nbio = head->so_nbio;
        so->so_proto = head->so_proto;
        so->so_timeo = head->so_timeo;
        so->so_pgid = head->so_pgid;
        so->so_send = head->so_send;
        so->so_receive = head->so_receive;
        so->so_uidinfo = head->so_uidinfo;
        so->so_cpid = head->so_cpid;
#ifdef MBUFTRACE
        so->so_mowner = head->so_mowner;
        so->so_rcv.sb_mowner = head->so_rcv.sb_mowner;
        so->so_snd.sb_mowner = head->so_snd.sb_mowner;
#endif
        if (soreserve(so, head->so_snd.sb_hiwat, head->so_rcv.sb_hiwat) != 0)
                goto out;
        so->so_snd.sb_lowat = head->so_snd.sb_lowat;
        so->so_rcv.sb_lowat = head->so_rcv.sb_lowat;
        so->so_rcv.sb_timeo = head->so_rcv.sb_timeo;
        so->so_snd.sb_timeo = head->so_snd.sb_timeo;
        so->so_rcv.sb_flags |= head->so_rcv.sb_flags & SB_AUTOSIZE;
        so->so_snd.sb_flags |= head->so_snd.sb_flags & SB_AUTOSIZE;
        soqinsque(head, so, soqueue);
        error = (*so->so_proto->pr_usrreq)(so, PRU_ATTACH, NULL, NULL,
            NULL, NULL);
        KASSERT(solocked(so));
        if (error != 0) {
                (void) soqremque(so, soqueue);
out:
                /*
                 * Remove acccept filter if one is present.
                 * XXX Is this really needed?
                 */
                if (so->so_accf != NULL)
                        (void)accept_filt_clear(so);
                soput(so);
                return NULL;
        }
        if (connstatus) {
                sorwakeup(head);
                cv_broadcast(&head->so_cv);
                so->so_state |= connstatus;
        }
        return so;
}

struct socket *
soget(bool waitok)
{
        struct socket *so;

        so = pool_cache_get(socket_cache, (waitok ? PR_WAITOK : PR_NOWAIT));
        if (__predict_false(so == NULL))
                return (NULL);
        memset(so, 0, sizeof(*so));
        TAILQ_INIT(&so->so_q0);
        TAILQ_INIT(&so->so_q);
        cv_init(&so->so_cv, "socket");
        cv_init(&so->so_rcv.sb_cv, "netio");
        cv_init(&so->so_snd.sb_cv, "netio");
        selinit(&so->so_rcv.sb_sel);
        selinit(&so->so_snd.sb_sel);
        so->so_rcv.sb_so = so;
        so->so_snd.sb_so = so;
        return so;
}

void
soput(struct socket *so)
{

        KASSERT(!cv_has_waiters(&so->so_cv));
        KASSERT(!cv_has_waiters(&so->so_rcv.sb_cv));
        KASSERT(!cv_has_waiters(&so->so_snd.sb_cv));
        seldestroy(&so->so_rcv.sb_sel);
        seldestroy(&so->so_snd.sb_sel);
        mutex_obj_free(so->so_lock);
        cv_destroy(&so->so_cv);
        cv_destroy(&so->so_rcv.sb_cv);
        cv_destroy(&so->so_snd.sb_cv);
        pool_cache_put(socket_cache, so);
}

void
soqinsque(struct socket *head, struct socket *so, int q)
{

        KASSERT(solocked2(head, so));

#ifdef DIAGNOSTIC
        if (so->so_onq != NULL)
                panic("soqinsque");
#endif

        so->so_head = head;
        if (q == 0) {
                head->so_q0len++;
                so->so_onq = &head->so_q0;
        } else {
                head->so_qlen++;
                so->so_onq = &head->so_q;
        }
        TAILQ_INSERT_TAIL(so->so_onq, so, so_qe);
}

int
soqremque(struct socket *so, int q)
{
        struct socket   *head;

        head = so->so_head;

        KASSERT(solocked(so));
        if (q == 0) {
                if (so->so_onq != &head->so_q0)
                        return (0);
                head->so_q0len--;
        } else {
                if (so->so_onq != &head->so_q)
                        return (0);
                head->so_qlen--;
        }
        KASSERT(solocked2(so, head));
        TAILQ_REMOVE(so->so_onq, so, so_qe);
        so->so_onq = NULL;
        so->so_head = NULL;
        return (1);
}

/*
 * 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)
{

        KASSERT(solocked(so));

        so->so_state |= SS_CANTSENDMORE;
        sowwakeup(so);
}

void
socantrcvmore(struct socket *so)
{

        KASSERT(solocked(so));

        so->so_state |= SS_CANTRCVMORE;
        sorwakeup(so);
}

/*
 * Wait for data to arrive at/drain from a socket buffer.
 */
int
sbwait(struct sockbuf *sb)
{
        struct socket *so;
        kmutex_t *lock;
        int error;

        so = sb->sb_so;

        KASSERT(solocked(so));

        sb->sb_flags |= SB_NOTIFY;
        lock = so->so_lock;
        if ((sb->sb_flags & SB_NOINTR) != 0)
                error = cv_timedwait(&sb->sb_cv, lock, sb->sb_timeo);
        else
                error = cv_timedwait_sig(&sb->sb_cv, lock, sb->sb_timeo);
        if (__predict_false(lock != so->so_lock))
                solockretry(so, lock);
        return error;
}

/*
 * Wakeup processes waiting on a socket buffer.
 * Do asynchronous notification via SIGIO
 * if the socket buffer has the SB_ASYNC flag set.
 */
void
sowakeup(struct socket *so, struct sockbuf *sb, int code)
{
        int band;

        KASSERT(solocked(so));
        KASSERT(sb->sb_so == so);

        if (code == POLL_IN)
                band = POLLIN|POLLRDNORM;
        else
                band = POLLOUT|POLLWRNORM;
        sb->sb_flags &= ~SB_NOTIFY;
        selnotify(&sb->sb_sel, band, NOTE_SUBMIT);
        cv_broadcast(&sb->sb_cv);
        if (sb->sb_flags & SB_ASYNC)
                fownsignal(so->so_pgid, SIGIO, code, band, so);
        if (sb->sb_flags & SB_UPCALL)
                (*so->so_upcall)(so, so->so_upcallarg, band, M_DONTWAIT);
}

/*
 * Reset a socket's lock pointer.  Wake all threads waiting on the
 * socket's condition variables so that they can restart their waits
 * using the new lock.  The existing lock must be held.
 */
void
solockreset(struct socket *so, kmutex_t *lock)
{

        KASSERT(solocked(so));

        so->so_lock = lock;
        cv_broadcast(&so->so_snd.sb_cv);
        cv_broadcast(&so->so_rcv.sb_cv);
        cv_broadcast(&so->so_cv);
}

/*
 * 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 poll() 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_CONTROL).
 * 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.
 */

int
sb_max_set(u_long new_sbmax)
{
        int s;

        if (new_sbmax < (16 * 1024))
                return (EINVAL);

        s = splsoftnet();
        sb_max = new_sbmax;
        sb_max_adj = (u_quad_t)new_sbmax * MCLBYTES / (MSIZE + MCLBYTES);
        splx(s);

        return (0);
}

int
soreserve(struct socket *so, u_long sndcc, u_long rcvcc)
{

        KASSERT(so->so_lock == NULL || solocked(so));

        /*
         * there's at least one application (a configure script of screen)
         * which expects a fifo is writable even if it has "some" bytes
         * in its buffer.
         * so we want to make sure (hiwat - lowat) >= (some bytes).
         *
         * PIPE_BUF here is an arbitrary value chosen as (some bytes) above.
         * we expect it's large enough for such applications.
         */
        u_long  lowat = MAX(sock_loan_thresh, MCLBYTES);
        u_long  hiwat = lowat + PIPE_BUF;

        if (sndcc < hiwat)
                sndcc = hiwat;
        if (sbreserve(&so->so_snd, sndcc, so) == 0)
                goto bad;
        if (sbreserve(&so->so_rcv, rcvcc, so) == 0)
                goto bad2;
        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 = lowat;
        if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
                so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
        return (0);
 bad2:
        sbrelease(&so->so_snd, so);
 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_long cc, struct socket *so)
{
        struct lwp *l = curlwp; /* XXX */
        rlim_t maxcc;
        struct uidinfo *uidinfo;

        KASSERT(so->so_lock == NULL || solocked(so));
        KASSERT(sb->sb_so == so);
        KASSERT(sb_max_adj != 0);

        if (cc == 0 || cc > sb_max_adj)
                return (0);

        maxcc = l->l_proc->p_rlimit[RLIMIT_SBSIZE].rlim_cur;

        uidinfo = so->so_uidinfo;
        if (!chgsbsize(uidinfo, &sb->sb_hiwat, cc, maxcc))
                return 0;
        sb->sb_mbmax = min(cc * 2, 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.  We do not assert
 * that the socket is held locked here: see sorflush().
 */
void
sbrelease(struct sockbuf *sb, struct socket *so)
{

        KASSERT(sb->sb_so == so);

        sbflush(sb);
        (void)chgsbsize(so->so_uidinfo, &sb->sb_hiwat, 0, RLIM_INFINITY);
        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.
 */

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

        KASSERT(solocked(sb->sb_so));

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

        if (m != sb->sb_lastrecord) {
                printf("sblastrecordchk: sb_mb %p sb_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;

        KASSERT(solocked(sb->sb_so));

        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: sb_mb %p sb_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);
        }
}
#endif /* SOCKBUF_DEBUG */

/*
 * Link a chain of records onto a socket buffer
 */
#define SBLINKRECORDCHAIN(sb, m0, mlast)                                \
do {                                                                    \
        if ((sb)->sb_lastrecord != NULL)                                \
                (sb)->sb_lastrecord->m_nextpkt = (m0);                  \
        else                                                            \
                (sb)->sb_mb = (m0);                                     \
        (sb)->sb_lastrecord = (mlast);                                  \
} while (/*CONSTCOND*/0)


#define SBLINKRECORD(sb, m0)                                            \
    SBLINKRECORDCHAIN(sb, m0, m0)

/*
 * 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.
 */
void
sbappend(struct sockbuf *sb, struct mbuf *m)
{
        struct mbuf     *n;

        KASSERT(solocked(sb->sb_so));

        if (m == 0)
                return;

#ifdef MBUFTRACE
        m_claimm(m, sb->sb_mowner);
#endif

        SBLASTRECORDCHK(sb, "sbappend 1");

        if ((n = sb->sb_lastrecord) != NULL) {
                /*
                 * XXX Would like to simply use sb_mbtail here, but
                 * XXX I need to verify that I won't miss an EOR that
                 * XXX way.
                 */
                do {
                        if (n->m_flags & M_EOR) {
                                sbappendrecord(sb, m); /* XXXXXX!!!! */
                                return;
                        }
                } while (n->m_next && (n = n->m_next));
        } else {
                /*
                 * If this is the first record in the socket buffer, it's
                 * also the last record.
                 */
                sb->sb_lastrecord = m;
        }
        sbcompress(sb, m, n);
        SBLASTRECORDCHK(sb, "sbappend 2");
}

/*
 * This version of sbappend() should only be used when the caller
 * absolutely knows that there will never be more than one record
 * in the socket buffer, that is, a stream protocol (such as TCP).
 */
void
sbappendstream(struct sockbuf *sb, struct mbuf *m)
{

        KASSERT(solocked(sb->sb_so));
        KDASSERT(m->m_nextpkt == NULL);
        KASSERT(sb->sb_mb == sb->sb_lastrecord);

        SBLASTMBUFCHK(sb, __func__);

#ifdef MBUFTRACE
        m_claimm(m, sb->sb_mowner);
#endif

        sbcompress(sb, m, sb->sb_mbtail);

        sb->sb_lastrecord = sb->sb_mb;
        SBLASTRECORDCHK(sb, __func__);
}

#ifdef SOCKBUF_DEBUG
void
sbcheck(struct sockbuf *sb)
{
        struct mbuf     *m, *m2;
        u_long          len, mbcnt;

        KASSERT(solocked(sb->sb_so));

        len = 0;
        mbcnt = 0;
        for (m = sb->sb_mb; m; m = m->m_nextpkt) {
                for (m2 = m; m2 != NULL; m2 = m2->m_next) {
                        len += m2->m_len;
                        mbcnt += MSIZE;
                        if (m2->m_flags & M_EXT)
                                mbcnt += m2->m_ext.ext_size;
                        if (m2->m_nextpkt != NULL)
                                panic("sbcheck nextpkt");
                }
        }
        if (len != sb->sb_cc || mbcnt != sb->sb_mbcnt) {
                printf("cc %lu != %lu || mbcnt %lu != %lu\n", len, sb->sb_cc,
                    mbcnt, sb->sb_mbcnt);
                panic("sbcheck");
        }
}
#endif

/*
 * As above, except the mbuf chain
 * begins a new record.
 */
void
sbappendrecord(struct sockbuf *sb, struct mbuf *m0)
{
        struct mbuf     *m;

        KASSERT(solocked(sb->sb_so));

        if (m0 == 0)
                return;

#ifdef MBUFTRACE
        m_claimm(m0, sb->sb_mowner);
#endif
        /*
         * Put the first mbuf on the queue.
         * Note this permits zero length records.
         */
        sballoc(sb, m0);
        SBLASTRECORDCHK(sb, "sbappendrecord 1");
        SBLINKRECORD(sb, 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 2");
}

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

        KASSERT(solocked(sb->sb_so));

        if (m0 == 0)
                return;

        SBLASTRECORDCHK(sb, "sbinsertoob 1");

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

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

                case MT_CONTROL:
                        if ((m = m->m_next) != NULL)
                                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 2");
}

/*
 * 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.
 */
int
sbappendaddr(struct sockbuf *sb, const struct sockaddr *asa, struct mbuf *m0,
        struct mbuf *control)
{
        struct mbuf     *m, *n, *nlast;
        int             space, len;

        KASSERT(solocked(sb->sb_so));

        space = asa->sa_len;

        if (m0 != NULL) {
                if ((m0->m_flags & M_PKTHDR) == 0)
                        panic("sbappendaddr");
                space += m0->m_pkthdr.len;
#ifdef MBUFTRACE
                m_claimm(m0, sb->sb_mowner);
#endif
        }
        for (n = control; n; n = n->m_next) {
                space += n->m_len;
                MCLAIM(n, sb->sb_mowner);
                if (n->m_next == 0)     /* keep pointer to last control buf */
                        break;
        }
        if (space > sbspace(sb))
                return (0);
        MGET(m, M_DONTWAIT, MT_SONAME);
        if (m == 0)
                return (0);
        MCLAIM(m, sb->sb_mowner);
        /*
         * XXX avoid 'comparison always true' warning which isn't easily
         * avoided.
         */
        len = asa->sa_len;
        if (len > MLEN) {
                MEXTMALLOC(m, asa->sa_len, M_NOWAIT);
                if ((m->m_flags & M_EXT) == 0) {
                        m_free(m);
                        return (0);
                }
        }
        m->m_len = asa->sa_len;
        memcpy(mtod(m, void *), asa, asa->sa_len);
        if (n)
                n->m_next = m0;         /* concatenate data to control */
        else
                control = m0;
        m->m_next = control;

        SBLASTRECORDCHK(sb, "sbappendaddr 1");

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

        sb->sb_mbtail = nlast;
        SBLASTMBUFCHK(sb, "sbappendaddr");
        SBLASTRECORDCHK(sb, "sbappendaddr 2");

        return (1);
}

/*
 * Helper for sbappendchainaddr: prepend a struct sockaddr* to
 * an mbuf chain.
 */
static inline struct mbuf *
m_prepend_sockaddr(struct sockbuf *sb, struct mbuf *m0,
                   const struct sockaddr *asa)
{
        struct mbuf *m;
        const int salen = asa->sa_len;

        KASSERT(solocked(sb->sb_so));

        /* only the first in each chain need be a pkthdr */
        MGETHDR(m, M_DONTWAIT, MT_SONAME);
        if (m == 0)
                return (0);
        MCLAIM(m, sb->sb_mowner);
#ifdef notyet
        if (salen > MHLEN) {
                MEXTMALLOC(m, salen, M_NOWAIT);
                if ((m->m_flags & M_EXT) == 0) {
                        m_free(m);
                        return (0);
                }
        }
#else
        KASSERT(salen <= MHLEN);
#endif
        m->m_len = salen;
        memcpy(mtod(m, void *), asa, salen);
        m->m_next = m0;
        m->m_pkthdr.len = salen + m0->m_pkthdr.len;

        return m;
}

int
sbappendaddrchain(struct sockbuf *sb, const struct sockaddr *asa,
                  struct mbuf *m0, int sbprio)
{
        int space;
        struct mbuf *m, *n, *n0, *nlast;
        int error;

        KASSERT(solocked(sb->sb_so));

        /*
         * XXX sbprio reserved for encoding priority of this* request:
         *  SB_PRIO_NONE --> honour normal sb limits
         *  SB_PRIO_ONESHOT_OVERFLOW --> if socket has any space,
         *      take whole chain. Intended for large requests
         *      that should be delivered atomically (all, or none).
         * SB_PRIO_OVERDRAFT -- allow a small (2*MLEN) overflow
         *       over normal socket limits, for messages indicating
         *       buffer overflow in earlier normal/lower-priority messages
         * SB_PRIO_BESTEFFORT -->  ignore limits entirely.
         *       Intended for  kernel-generated messages only.
         *        Up to generator to avoid total mbuf resource exhaustion.
         */
        (void)sbprio;

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

        space = sbspace(sb);

#ifdef notyet
        /*
         * Enforce SB_PRIO_* limits as described above.
         */
#endif

        n0 = NULL;
        nlast = NULL;
        for (m = m0; m; m = m->m_nextpkt) {
                struct mbuf *np;

#ifdef MBUFTRACE
                m_claimm(m, sb->sb_mowner);
#endif

                /* Prepend sockaddr to this record (m) of input chain m0 */
                n = m_prepend_sockaddr(sb, m, asa);
                if (n == NULL) {
                        error = ENOBUFS;
                        goto bad;
                }

                /* Append record (asa+m) to end of new chain n0 */
                if (n0 == NULL) {
                        n0 = n;
                } else {
                        nlast->m_nextpkt = n;
                }
                /* Keep track of last record on new chain */
                nlast = n;

                for (np = n; np; np = np->m_next)
                        sballoc(sb, np);
        }

        SBLASTRECORDCHK(sb, "sbappendaddrchain 1");

        /* Drop the entire chain of (asa+m) records onto the socket */
        SBLINKRECORDCHAIN(sb, n0, nlast);

        SBLASTRECORDCHK(sb, "sbappendaddrchain 2");

        for (m = nlast; m->m_next; m = m->m_next)
                ;
        sb->sb_mbtail = m;
        SBLASTMBUFCHK(sb, "sbappendaddrchain");

        return (1);

bad:
        /*
         * On error, free the prepended addreseses. For consistency
         * with sbappendaddr(), leave it to our caller to free
         * the input record chain passed to us as m0.
         */
        while ((n = n0) != NULL) {
                struct mbuf *np;

                /* Undo the sballoc() of this record */
                for (np = n; np; np = np->m_next)
                        sbfree(sb, np);

                n0 = n->m_nextpkt;      /* iterate at next prepended address */
                MFREE(n, np);           /* free prepended address (not data) */
        }
        return 0;
}


int
sbappendcontrol(struct sockbuf *sb, struct mbuf *m0, struct mbuf *control)
{
        struct mbuf     *m, *mlast, *n;
        int             space;

        KASSERT(solocked(sb->sb_so));

        space = 0;
        if (control == 0)
                panic("sbappendcontrol");
        for (m = control; ; m = m->m_next) {
                space += m->m_len;
                MCLAIM(m, sb->sb_mowner);
                if (m->m_next == 0)
                        break;
        }
        n = m;                  /* save pointer to last control buffer */
        for (m = m0; m; m = m->m_next) {
                MCLAIM(m, sb->sb_mowner);
                space += m->m_len;
        }
        if (space > sbspace(sb))
                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;
        SBLINKRECORD(sb, control);

        sb->sb_mbtail = mlast;
        SBLASTMBUFCHK(sb, "sbappendcontrol");
        SBLASTRECORDCHK(sb, "sbappendcontrol 2");

        return (1);
}

/*
 * Compress mbuf chain m into the socket
 * buffer sb following mbuf n.  If n
 * is null, the buffer is presumed empty.
 */
void
sbcompress(struct sockbuf *sb, struct mbuf *m, struct mbuf *n)
{
        int             eor;
        struct mbuf     *o;

        KASSERT(solocked(sb->sb_so));

        eor = 0;
        while (m) {
                eor |= m->m_flags & M_EOR;
                if (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 (n && (n->m_flags & M_EOR) == 0 &&
                    /* M_TRAILINGSPACE() checks buffer writeability */
                    m->m_len <= MCLBYTES / 4 && /* XXX Don't copy too much */
                    m->m_len <= M_TRAILINGSPACE(n) &&
                    n->m_type == m->m_type) {
                        memcpy(mtod(n, char *) + n->m_len, mtod(m, void *),
                            (unsigned)m->m_len);
                        n->m_len += m->m_len;
                        sb->sb_cc += m->m_len;
                        m = m_free(m);
                        continue;
                }
                if (n)
                        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 = 0;
        }
        if (eor) {
                if (n)
                        n->m_flags |= eor;
                else
                        printf("semi-panic: sbcompress\n");
        }
        SBLASTMBUFCHK(sb, __func__);
}

/*
 * Free all mbufs in a sockbuf.
 * Check that all resources are reclaimed.
 */
void
sbflush(struct sockbuf *sb)
{

        KASSERT(solocked(sb->sb_so));
        KASSERT((sb->sb_flags & SB_LOCK) == 0);

        while (sb->sb_mbcnt)
                sbdrop(sb, (int)sb->sb_cc);

        KASSERT(sb->sb_cc == 0);
        KASSERT(sb->sb_mb == NULL);
        KASSERT(sb->sb_mbtail == NULL);
        KASSERT(sb->sb_lastrecord == NULL);
}

/*
 * Drop data from (the front of) a sockbuf.
 */
void
sbdrop(struct sockbuf *sb, int len)
{
        struct mbuf     *m, *mn, *next;

        KASSERT(solocked(sb->sb_so));

        next = (m = sb->sb_mb) ? m->m_nextpkt : 0;
        while (len > 0) {
                if (m == 0) {
                        if (next == 0)
                                panic("sbdrop");
                        m = next;
                        next = m->m_nextpkt;
                        continue;
                }
                if (m->m_len > len) {
                        m->m_len -= len;
                        m->m_data += len;
                        sb->sb_cc -= len;
                        break;
                }
                len -= m->m_len;
                sbfree(sb, m);
                MFREE(m, mn);
                m = mn;
        }
        while (m && m->m_len == 0) {
                sbfree(sb, m);
                MFREE(m, mn);
                m = mn;
        }
        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;
}

/*
 * 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;

        KASSERT(solocked(sb->sb_so));

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

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

        if (CMSG_SPACE(size) > MCLBYTES) {
                printf("sbcreatecontrol: message too large %d\n", size);
                return NULL;
        }

        if ((m = m_get(M_DONTWAIT, MT_CONTROL)) == NULL)
                return ((struct mbuf *) NULL);
        if (CMSG_SPACE(size) > MLEN) {
                MCLGET(m, M_DONTWAIT);
                if ((m->m_flags & M_EXT) == 0) {
                        m_free(m);
                        return NULL;
                }
        }
        cp = mtod(m, struct cmsghdr *);
        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);
}

void
solockretry(struct socket *so, kmutex_t *lock)
{

        while (lock != so->so_lock) {
                mutex_exit(lock);
                lock = so->so_lock;
                mutex_enter(lock);
        }
}

bool
solocked(struct socket *so)
{

        return mutex_owned(so->so_lock);
}

bool
solocked2(struct socket *so1, struct socket *so2)
{
        kmutex_t *lock;

        lock = so1->so_lock;
        if (lock != so2->so_lock)
                return false;
        return mutex_owned(lock);
}

/*
 * Assign a default lock to a new socket.  For PRU_ATTACH, and done by
 * protocols that do not have special locking requirements.
 */
void
sosetlock(struct socket *so)
{
        kmutex_t *lock;

        if (so->so_lock == NULL) {
                lock = softnet_lock;
                so->so_lock = lock;
                mutex_obj_hold(lock);
                mutex_enter(lock);
        }

        /* In all cases, lock must be held on return from PRU_ATTACH. */
        KASSERT(solocked(so));
}

/*
 * 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, int wf)
{
        struct socket *so;
        kmutex_t *lock;
        int error;

        KASSERT(solocked(sb->sb_so));

        for (;;) {
                if (__predict_true((sb->sb_flags & SB_LOCK) == 0)) {
                        sb->sb_flags |= SB_LOCK;
                        return 0;
                }
                if (wf != M_WAITOK)
                        return EWOULDBLOCK;
                so = sb->sb_so;
                lock = so->so_lock;
                if ((sb->sb_flags & SB_NOINTR) != 0) {
                        cv_wait(&so->so_cv, lock);
                        error = 0;
                } else
                        error = cv_wait_sig(&so->so_cv, lock);
                if (__predict_false(lock != so->so_lock))
                        solockretry(so, lock);
                if (error != 0)
                        return error;
        }
}

void
sbunlock(struct sockbuf *sb)
{
        struct socket *so;

        so = sb->sb_so;

        KASSERT(solocked(so));
        KASSERT((sb->sb_flags & SB_LOCK) != 0);

        sb->sb_flags &= ~SB_LOCK;
        cv_broadcast(&so->so_cv);
}

int
sowait(struct socket *so, bool catch, int timo)
{
        kmutex_t *lock;
        int error;

        KASSERT(solocked(so));
        KASSERT(catch || timo != 0);

        lock = so->so_lock;
        if (catch)
                error = cv_timedwait_sig(&so->so_cv, lock, timo);
        else
                error = cv_timedwait(&so->so_cv, lock, timo);
        if (__predict_false(lock != so->so_lock))
                solockretry(so, lock);
        return error;
}