FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_socket.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1982, 1986, 1988, 1990, 1993
      *      The Regents of the University of California.
      * Copyright (c) 2004 The FreeBSD Foundation
      * Copyright (c) 2004-2008 Robert N. M. Watson
      * 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_socket.c       8.3 (Berkeley) 4/15/94
     */
    
    /*
     * Comments on the socket life cycle:
     *
     * soalloc() sets of socket layer state for a socket, called only by
     * socreate() and sonewconn().  Socket layer private.
     *
     * sodealloc() tears down socket layer state for a socket, called only by
     * sofree() and sonewconn().  Socket layer private.
     *
     * pru_attach() associates protocol layer state with an allocated socket;
     * called only once, may fail, aborting socket allocation.  This is called
     * from socreate() and sonewconn().  Socket layer private.
     *
     * pru_detach() disassociates protocol layer state from an attached socket,
     * and will be called exactly once for sockets in which pru_attach() has
     * been successfully called.  If pru_attach() returned an error,
     * pru_detach() will not be called.  Socket layer private.
     *
     * pru_abort() and pru_close() notify the protocol layer that the last
     * consumer of a socket is starting to tear down the socket, and that the
     * protocol should terminate the connection.  Historically, pru_abort() also
     * detached protocol state from the socket state, but this is no longer the
     * case.
     *
     * socreate() creates a socket and attaches protocol state.  This is a public
     * interface that may be used by socket layer consumers to create new
     * sockets.
     *
     * sonewconn() creates a socket and attaches protocol state.  This is a
     * public interface  that may be used by protocols to create new sockets when
     * a new connection is received and will be available for accept() on a
     * listen socket.
     *
     * soclose() destroys a socket after possibly waiting for it to disconnect.
     * This is a public interface that socket consumers should use to close and
     * release a socket when done with it.
     *
     * soabort() destroys a socket without waiting for it to disconnect (used
     * only for incoming connections that are already partially or fully
     * connected).  This is used internally by the socket layer when clearing
     * listen socket queues (due to overflow or close on the listen socket), but
     * is also a public interface protocols may use to abort connections in
     * their incomplete listen queues should they no longer be required.  Sockets
     * placed in completed connection listen queues should not be aborted for
     * reasons described in the comment above the soclose() implementation.  This
     * is not a general purpose close routine, and except in the specific
     * circumstances described here, should not be used.
     *
     * sofree() will free a socket and its protocol state if all references on
     * the socket have been released, and is the public interface to attempt to
     * free a socket when a reference is removed.  This is a socket layer private
     * interface.
     *
     * NOTE: In addition to socreate() and soclose(), which provide a single
     * socket reference to the consumer to be managed as required, there are two
     * calls to explicitly manage socket references, soref(), and sorele().
     * Currently, these are generally required only when transitioning a socket
     * from a listen queue to a file descriptor, in order to prevent garbage
     * collection of the socket at an untimely moment.  For a number of reasons,
     * these interfaces are not preferred, and should be avoided.
     *
     * NOTE: With regard to VNETs the general rule is that callers do not set
     * curvnet. Exceptions to this rule include soabort(), sodisconnect(),
    * sofree() (and with that sorele(), sotryfree()), as well as sonewconn()
    * and sorflush(), which are usually called from a pre-set VNET context.
    * sopoll() currently does not need a VNET context to be set.
    */
   
   #include <sys/cdefs.h>
   __FBSDID("$FreeBSD$");
   
   #include "opt_inet.h"
   #include "opt_inet6.h"
   #include "opt_kern_tls.h"
   #include "opt_sctp.h"
   
   #include <sys/param.h>
   #include <sys/systm.h>
   #include <sys/capsicum.h>
   #include <sys/fcntl.h>
   #include <sys/limits.h>
   #include <sys/lock.h>
   #include <sys/mac.h>
   #include <sys/malloc.h>
   #include <sys/mbuf.h>
   #include <sys/mutex.h>
   #include <sys/domain.h>
   #include <sys/file.h>                   /* for struct knote */
   #include <sys/hhook.h>
   #include <sys/kernel.h>
   #include <sys/khelp.h>
   #include <sys/ktls.h>
   #include <sys/event.h>
   #include <sys/eventhandler.h>
   #include <sys/poll.h>
   #include <sys/proc.h>
   #include <sys/protosw.h>
   #include <sys/sbuf.h>
   #include <sys/socket.h>
   #include <sys/socketvar.h>
   #include <sys/resourcevar.h>
   #include <net/route.h>
   #include <sys/signalvar.h>
   #include <sys/stat.h>
   #include <sys/sx.h>
   #include <sys/sysctl.h>
   #include <sys/taskqueue.h>
   #include <sys/uio.h>
   #include <sys/un.h>
   #include <sys/unpcb.h>
   #include <sys/jail.h>
   #include <sys/syslog.h>
   #include <netinet/in.h>
   #include <netinet/in_pcb.h>
   #include <netinet/tcp.h>
   
   #include <net/vnet.h>
   
   #include <security/mac/mac_framework.h>
   
   #include <vm/uma.h>
   
   #ifdef COMPAT_FREEBSD32
   #include <sys/mount.h>
   #include <sys/sysent.h>
   #include <compat/freebsd32/freebsd32.h>
   #endif
   
   static int      soreceive_rcvoob(struct socket *so, struct uio *uio,
                       int flags);
   static void     so_rdknl_lock(void *);
   static void     so_rdknl_unlock(void *);
   static void     so_rdknl_assert_lock(void *, int);
   static void     so_wrknl_lock(void *);
   static void     so_wrknl_unlock(void *);
   static void     so_wrknl_assert_lock(void *, int);
   
   static void     filt_sordetach(struct knote *kn);
   static int      filt_soread(struct knote *kn, long hint);
   static void     filt_sowdetach(struct knote *kn);
   static int      filt_sowrite(struct knote *kn, long hint);
   static int      filt_soempty(struct knote *kn, long hint);
   static int inline hhook_run_socket(struct socket *so, void *hctx, int32_t h_id);
   fo_kqfilter_t   soo_kqfilter;
   
   static struct filterops soread_filtops = {
           .f_isfd = 1,
           .f_detach = filt_sordetach,
           .f_event = filt_soread,
   };
   static struct filterops sowrite_filtops = {
           .f_isfd = 1,
           .f_detach = filt_sowdetach,
           .f_event = filt_sowrite,
   };
   static struct filterops soempty_filtops = {
           .f_isfd = 1,
           .f_detach = filt_sowdetach,
           .f_event = filt_soempty,
   };
   
   so_gen_t        so_gencnt;      /* generation count for sockets */
   
   MALLOC_DEFINE(M_SONAME, "soname", "socket name");
   MALLOC_DEFINE(M_PCB, "pcb", "protocol control block");
   
   #define VNET_SO_ASSERT(so)                                              \
           VNET_ASSERT(curvnet != NULL,                                    \
               ("%s:%d curvnet is NULL, so=%p", __func__, __LINE__, (so)));
   
   VNET_DEFINE(struct hhook_head *, socket_hhh[HHOOK_SOCKET_LAST + 1]);
   #define V_socket_hhh            VNET(socket_hhh)
   
   /*
    * Limit on the number of connections in the listen queue waiting
    * for accept(2).
    * NB: The original sysctl somaxconn is still available but hidden
    * to prevent confusion about the actual purpose of this number.
    */
   static u_int somaxconn = SOMAXCONN;
   
   static int
   sysctl_somaxconn(SYSCTL_HANDLER_ARGS)
   {
           int error;
           int val;
   
           val = somaxconn;
           error = sysctl_handle_int(oidp, &val, 0, req);
           if (error || !req->newptr )
                   return (error);
   
           /*
            * The purpose of the UINT_MAX / 3 limit, is so that the formula
            *   3 * so_qlimit / 2
            * below, will not overflow.
            */
   
           if (val < 1 || val > UINT_MAX / 3)
                   return (EINVAL);
   
           somaxconn = val;
           return (0);
   }
   SYSCTL_PROC(_kern_ipc, OID_AUTO, soacceptqueue,
       CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, sizeof(int),
       sysctl_somaxconn, "I",
       "Maximum listen socket pending connection accept queue size");
   SYSCTL_PROC(_kern_ipc, KIPC_SOMAXCONN, somaxconn,
       CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_SKIP | CTLFLAG_MPSAFE, 0,
       sizeof(int), sysctl_somaxconn, "I",
       "Maximum listen socket pending connection accept queue size (compat)");
   
   static int numopensockets;
   SYSCTL_INT(_kern_ipc, OID_AUTO, numopensockets, CTLFLAG_RD,
       &numopensockets, 0, "Number of open sockets");
   
   /*
    * so_global_mtx protects so_gencnt, numopensockets, and the per-socket
    * so_gencnt field.
    */
   static struct mtx so_global_mtx;
   MTX_SYSINIT(so_global_mtx, &so_global_mtx, "so_glabel", MTX_DEF);
   
   /*
    * General IPC sysctl name space, used by sockets and a variety of other IPC
    * types.
    */
   SYSCTL_NODE(_kern, KERN_IPC, ipc, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
       "IPC");
   
   /*
    * Initialize the socket subsystem and set up the socket
    * memory allocator.
    */
   static uma_zone_t socket_zone;
   int     maxsockets;
   
   static void
   socket_zone_change(void *tag)
   {
   
           maxsockets = uma_zone_set_max(socket_zone, maxsockets);
   }
   
   static void
   socket_hhook_register(int subtype)
   {
   
           if (hhook_head_register(HHOOK_TYPE_SOCKET, subtype,
               &V_socket_hhh[subtype],
               HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
                   printf("%s: WARNING: unable to register hook\n", __func__);
   }
   
   static void
   socket_hhook_deregister(int subtype)
   {
   
           if (hhook_head_deregister(V_socket_hhh[subtype]) != 0)
                   printf("%s: WARNING: unable to deregister hook\n", __func__);
   }
   
   static void
   socket_init(void *tag)
   {
   
           socket_zone = uma_zcreate("socket", sizeof(struct socket), NULL, NULL,
               NULL, NULL, UMA_ALIGN_PTR, 0);
           maxsockets = uma_zone_set_max(socket_zone, maxsockets);
           uma_zone_set_warning(socket_zone, "kern.ipc.maxsockets limit reached");
           EVENTHANDLER_REGISTER(maxsockets_change, socket_zone_change, NULL,
               EVENTHANDLER_PRI_FIRST);
   }
   SYSINIT(socket, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY, socket_init, NULL);
   
   static void
   socket_vnet_init(const void *unused __unused)
   {
           int i;
   
           /* We expect a contiguous range */
           for (i = 0; i <= HHOOK_SOCKET_LAST; i++)
                   socket_hhook_register(i);
   }
   VNET_SYSINIT(socket_vnet_init, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY,
       socket_vnet_init, NULL);
   
   static void
   socket_vnet_uninit(const void *unused __unused)
   {
           int i;
   
           for (i = 0; i <= HHOOK_SOCKET_LAST; i++)
                   socket_hhook_deregister(i);
   }
   VNET_SYSUNINIT(socket_vnet_uninit, SI_SUB_PROTO_DOMAININIT, SI_ORDER_ANY,
       socket_vnet_uninit, NULL);
   
   /*
    * Initialise maxsockets.  This SYSINIT must be run after
    * tunable_mbinit().
    */
   static void
   init_maxsockets(void *ignored)
   {
   
           TUNABLE_INT_FETCH("kern.ipc.maxsockets", &maxsockets);
           maxsockets = imax(maxsockets, maxfiles);
   }
   SYSINIT(param, SI_SUB_TUNABLES, SI_ORDER_ANY, init_maxsockets, NULL);
   
   /*
    * Sysctl to get and set the maximum global sockets limit.  Notify protocols
    * of the change so that they can update their dependent limits as required.
    */
   static int
   sysctl_maxsockets(SYSCTL_HANDLER_ARGS)
   {
           int error, newmaxsockets;
   
           newmaxsockets = maxsockets;
           error = sysctl_handle_int(oidp, &newmaxsockets, 0, req);
           if (error == 0 && req->newptr && newmaxsockets != maxsockets) {
                   if (newmaxsockets > maxsockets &&
                       newmaxsockets <= maxfiles) {
                           maxsockets = newmaxsockets;
                           EVENTHANDLER_INVOKE(maxsockets_change);
                   } else
                           error = EINVAL;
           }
           return (error);
   }
   SYSCTL_PROC(_kern_ipc, OID_AUTO, maxsockets,
       CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, &maxsockets, 0,
       sysctl_maxsockets, "IU",
       "Maximum number of sockets available");
   
   /*
    * Socket operation routines.  These routines are called by the routines in
    * sys_socket.c or from a system process, and implement the semantics of
    * socket operations by switching out to the protocol specific routines.
    */
   
   /*
    * Get a socket structure from our zone, and initialize it.  Note that it
    * would probably be better to allocate socket and PCB at the same time, but
    * I'm not convinced that all the protocols can be easily modified to do
    * this.
    *
    * soalloc() returns a socket with a ref count of 0.
    */
   static struct socket *
   soalloc(struct vnet *vnet)
   {
           struct socket *so;
   
           so = uma_zalloc(socket_zone, M_NOWAIT | M_ZERO);
           if (so == NULL)
                   return (NULL);
   #ifdef MAC
           if (mac_socket_init(so, M_NOWAIT) != 0) {
                   uma_zfree(socket_zone, so);
                   return (NULL);
           }
   #endif
           if (khelp_init_osd(HELPER_CLASS_SOCKET, &so->osd)) {
                   uma_zfree(socket_zone, so);
                   return (NULL);
           }
   
           /*
            * The socket locking protocol allows to lock 2 sockets at a time,
            * however, the first one must be a listening socket.  WITNESS lacks
            * a feature to change class of an existing lock, so we use DUPOK.
            */
           mtx_init(&so->so_lock, "socket", NULL, MTX_DEF | MTX_DUPOK);
           mtx_init(&so->so_snd_mtx, "so_snd", NULL, MTX_DEF);
           mtx_init(&so->so_rcv_mtx, "so_rcv", NULL, MTX_DEF);
           so->so_rcv.sb_sel = &so->so_rdsel;
           so->so_snd.sb_sel = &so->so_wrsel;
           sx_init(&so->so_snd_sx, "so_snd_sx");
           sx_init(&so->so_rcv_sx, "so_rcv_sx");
           TAILQ_INIT(&so->so_snd.sb_aiojobq);
           TAILQ_INIT(&so->so_rcv.sb_aiojobq);
           TASK_INIT(&so->so_snd.sb_aiotask, 0, soaio_snd, so);
           TASK_INIT(&so->so_rcv.sb_aiotask, 0, soaio_rcv, so);
   #ifdef VIMAGE
           VNET_ASSERT(vnet != NULL, ("%s:%d vnet is NULL, so=%p",
               __func__, __LINE__, so));
           so->so_vnet = vnet;
   #endif
           /* We shouldn't need the so_global_mtx */
           if (hhook_run_socket(so, NULL, HHOOK_SOCKET_CREATE)) {
                   /* Do we need more comprehensive error returns? */
                   uma_zfree(socket_zone, so);
                   return (NULL);
           }
           mtx_lock(&so_global_mtx);
           so->so_gencnt = ++so_gencnt;
           ++numopensockets;
   #ifdef VIMAGE
           vnet->vnet_sockcnt++;
   #endif
           mtx_unlock(&so_global_mtx);
   
           return (so);
   }
   
   /*
    * Free the storage associated with a socket at the socket layer, tear down
    * locks, labels, etc.  All protocol state is assumed already to have been
    * torn down (and possibly never set up) by the caller.
    */
   void
   sodealloc(struct socket *so)
   {
   
           KASSERT(so->so_count == 0, ("sodealloc(): so_count %d", so->so_count));
           KASSERT(so->so_pcb == NULL, ("sodealloc(): so_pcb != NULL"));
   
           mtx_lock(&so_global_mtx);
           so->so_gencnt = ++so_gencnt;
           --numopensockets;       /* Could be below, but faster here. */
   #ifdef VIMAGE
           VNET_ASSERT(so->so_vnet != NULL, ("%s:%d so_vnet is NULL, so=%p",
               __func__, __LINE__, so));
           so->so_vnet->vnet_sockcnt--;
   #endif
           mtx_unlock(&so_global_mtx);
   #ifdef MAC
           mac_socket_destroy(so);
   #endif
           hhook_run_socket(so, NULL, HHOOK_SOCKET_CLOSE);
   
           khelp_destroy_osd(&so->osd);
           if (SOLISTENING(so)) {
                   if (so->sol_accept_filter != NULL)
                           accept_filt_setopt(so, NULL);
           } else {
                   if (so->so_rcv.sb_hiwat)
                           (void)chgsbsize(so->so_cred->cr_uidinfo,
                               &so->so_rcv.sb_hiwat, 0, RLIM_INFINITY);
                   if (so->so_snd.sb_hiwat)
                           (void)chgsbsize(so->so_cred->cr_uidinfo,
                               &so->so_snd.sb_hiwat, 0, RLIM_INFINITY);
                   sx_destroy(&so->so_snd_sx);
                   sx_destroy(&so->so_rcv_sx);
                   mtx_destroy(&so->so_snd_mtx);
                   mtx_destroy(&so->so_rcv_mtx);
           }
           crfree(so->so_cred);
           mtx_destroy(&so->so_lock);
           uma_zfree(socket_zone, so);
   }
   
   /*
    * socreate returns a socket with a ref count of 1 and a file descriptor
    * reference.  The socket should be closed with soclose().
    */
   int
   socreate(int dom, struct socket **aso, int type, int proto,
       struct ucred *cred, struct thread *td)
   {
           struct protosw *prp;
           struct socket *so;
           int error;
   
           /*
            * XXX: divert(4) historically abused PF_INET.  Keep this compatibility
            * shim until all applications have been updated.
            */
           if (__predict_false(dom == PF_INET && type == SOCK_RAW &&
               proto == IPPROTO_DIVERT)) {
                   dom = PF_DIVERT;
                   printf("%s uses obsolete way to create divert(4) socket\n",
                       td->td_proc->p_comm);
           }
   
           prp = pffindproto(dom, type, proto);
           if (prp == NULL) {
                   /* No support for domain. */
                   if (pffinddomain(dom) == NULL)
                           return (EAFNOSUPPORT);
                   /* No support for socket type. */
                   if (proto == 0 && type != 0)
                           return (EPROTOTYPE);
                   return (EPROTONOSUPPORT);
           }
   
           MPASS(prp->pr_attach);
   
           if (IN_CAPABILITY_MODE(td) && (prp->pr_flags & PR_CAPATTACH) == 0)
                   return (ECAPMODE);
   
           if (prison_check_af(cred, prp->pr_domain->dom_family) != 0)
                   return (EPROTONOSUPPORT);
   
           so = soalloc(CRED_TO_VNET(cred));
           if (so == NULL)
                   return (ENOBUFS);
   
           so->so_type = type;
           so->so_cred = crhold(cred);
           if ((prp->pr_domain->dom_family == PF_INET) ||
               (prp->pr_domain->dom_family == PF_INET6) ||
               (prp->pr_domain->dom_family == PF_ROUTE))
                   so->so_fibnum = td->td_proc->p_fibnum;
           else
                   so->so_fibnum = 0;
           so->so_proto = prp;
   #ifdef MAC
           mac_socket_create(cred, so);
   #endif
           knlist_init(&so->so_rdsel.si_note, so, so_rdknl_lock, so_rdknl_unlock,
               so_rdknl_assert_lock);
           knlist_init(&so->so_wrsel.si_note, so, so_wrknl_lock, so_wrknl_unlock,
               so_wrknl_assert_lock);
           if ((prp->pr_flags & PR_SOCKBUF) == 0) {
                   so->so_snd.sb_mtx = &so->so_snd_mtx;
                   so->so_rcv.sb_mtx = &so->so_rcv_mtx;
           }
           /*
            * Auto-sizing of socket buffers is managed by the protocols and
            * the appropriate flags must be set in the pru_attach function.
            */
           CURVNET_SET(so->so_vnet);
           error = prp->pr_attach(so, proto, td);
           CURVNET_RESTORE();
           if (error) {
                   sodealloc(so);
                   return (error);
           }
           soref(so);
           *aso = so;
           return (0);
   }
   
   #ifdef REGRESSION
   static int regression_sonewconn_earlytest = 1;
   SYSCTL_INT(_regression, OID_AUTO, sonewconn_earlytest, CTLFLAG_RW,
       &regression_sonewconn_earlytest, 0, "Perform early sonewconn limit test");
   #endif
   
   static struct timeval overinterval = { 60, 0 };
   SYSCTL_TIMEVAL_SEC(_kern_ipc, OID_AUTO, sooverinterval, CTLFLAG_RW,
       &overinterval,
       "Delay in seconds between warnings for listen socket overflows");
   
   /*
    * When an attempt at a new connection is noted on a socket which supports
    * accept(2), the protocol has two options:
    * 1) Call legacy sonewconn() function, which would call protocol attach
    *    method, same as used for socket(2).
    * 2) Call solisten_clone(), do attach that is specific to a cloned connection,
    *    and then call solisten_enqueue().
    *
    * Note: the ref count on the socket is 0 on return.
    */
   struct socket *
   solisten_clone(struct socket *head)
   {
           struct sbuf descrsb;
           struct socket *so;
           int len, overcount;
           u_int qlen;
           const char localprefix[] = "local:";
           char descrbuf[SUNPATHLEN + sizeof(localprefix)];
   #if defined(INET6)
           char addrbuf[INET6_ADDRSTRLEN];
   #elif defined(INET)
           char addrbuf[INET_ADDRSTRLEN];
   #endif
           bool dolog, over;
   
           SOLISTEN_LOCK(head);
           over = (head->sol_qlen > 3 * head->sol_qlimit / 2);
   #ifdef REGRESSION
           if (regression_sonewconn_earlytest && over) {
   #else
           if (over) {
   #endif
                   head->sol_overcount++;
                   dolog = !!ratecheck(&head->sol_lastover, &overinterval);
   
                   /*
                    * If we're going to log, copy the overflow count and queue
                    * length from the listen socket before dropping the lock.
                    * Also, reset the overflow count.
                    */
                   if (dolog) {
                           overcount = head->sol_overcount;
                           head->sol_overcount = 0;
                           qlen = head->sol_qlen;
                   }
                   SOLISTEN_UNLOCK(head);
   
                   if (dolog) {
                           /*
                            * Try to print something descriptive about the
                            * socket for the error message.
                            */
                           sbuf_new(&descrsb, descrbuf, sizeof(descrbuf),
                               SBUF_FIXEDLEN);
                           switch (head->so_proto->pr_domain->dom_family) {
   #if defined(INET) || defined(INET6)
   #ifdef INET
                           case AF_INET:
   #endif
   #ifdef INET6
                           case AF_INET6:
                                   if (head->so_proto->pr_domain->dom_family ==
                                       AF_INET6 ||
                                       (sotoinpcb(head)->inp_inc.inc_flags &
                                       INC_ISIPV6)) {
                                           ip6_sprintf(addrbuf,
                                               &sotoinpcb(head)->inp_inc.inc6_laddr);
                                           sbuf_printf(&descrsb, "[%s]", addrbuf);
                                   } else
   #endif
                                   {
   #ifdef INET
                                           inet_ntoa_r(
                                               sotoinpcb(head)->inp_inc.inc_laddr,
                                               addrbuf);
                                           sbuf_cat(&descrsb, addrbuf);
   #endif
                                   }
                                   sbuf_printf(&descrsb, ":%hu (proto %u)",
                                       ntohs(sotoinpcb(head)->inp_inc.inc_lport),
                                       head->so_proto->pr_protocol);
                                   break;
   #endif /* INET || INET6 */
                           case AF_UNIX:
                                   sbuf_cat(&descrsb, localprefix);
                                   if (sotounpcb(head)->unp_addr != NULL)
                                           len =
                                               sotounpcb(head)->unp_addr->sun_len -
                                               offsetof(struct sockaddr_un,
                                               sun_path);
                                   else
                                           len = 0;
                                   if (len > 0)
                                           sbuf_bcat(&descrsb,
                                               sotounpcb(head)->unp_addr->sun_path,
                                               len);
                                   else
                                           sbuf_cat(&descrsb, "(unknown)");
                                   break;
                           }
   
                           /*
                            * If we can't print something more specific, at least
                            * print the domain name.
                            */
                           if (sbuf_finish(&descrsb) != 0 ||
                               sbuf_len(&descrsb) <= 0) {
                                   sbuf_clear(&descrsb);
                                   sbuf_cat(&descrsb,
                                       head->so_proto->pr_domain->dom_name ?:
                                       "unknown");
                                   sbuf_finish(&descrsb);
                           }
                           KASSERT(sbuf_len(&descrsb) > 0,
                               ("%s: sbuf creation failed", __func__));
                           /*
                            * Preserve the historic listen queue overflow log
                            * message, that starts with "sonewconn:".  It has
                            * been known to sysadmins for years and also test
                            * sys/kern/sonewconn_overflow checks for it.
                            */
                           if (head->so_cred == 0) {
                                   log(LOG_DEBUG, "sonewconn: pcb %p (%s): "
                                       "Listen queue overflow: %i already in "
                                       "queue awaiting acceptance (%d "
                                       "occurrences)\n", head->so_pcb,
                                       sbuf_data(&descrsb),
                                   qlen, overcount);
                           } else {
                                   log(LOG_DEBUG, "sonewconn: pcb %p (%s): "
                                       "Listen queue overflow: "
                                       "%i already in queue awaiting acceptance "
                                       "(%d occurrences), euid %d, rgid %d, jail %s\n",
                                       head->so_pcb, sbuf_data(&descrsb), qlen,
                                       overcount, head->so_cred->cr_uid,
                                       head->so_cred->cr_rgid,
                                       head->so_cred->cr_prison ?
                                           head->so_cred->cr_prison->pr_name :
                                           "not_jailed");
                           }
                           sbuf_delete(&descrsb);
   
                           overcount = 0;
                   }
   
                   return (NULL);
           }
           SOLISTEN_UNLOCK(head);
           VNET_ASSERT(head->so_vnet != NULL, ("%s: so %p vnet is NULL",
               __func__, head));
           so = soalloc(head->so_vnet);
           if (so == NULL) {
                   log(LOG_DEBUG, "%s: pcb %p: New socket allocation failure: "
                       "limit reached or out of memory\n",
                       __func__, head->so_pcb);
                   return (NULL);
           }
           so->so_listen = head;
           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;
           so->so_fibnum = head->so_fibnum;
           so->so_proto = head->so_proto;
           so->so_cred = crhold(head->so_cred);
   #ifdef MAC
           mac_socket_newconn(head, so);
   #endif
           knlist_init(&so->so_rdsel.si_note, so, so_rdknl_lock, so_rdknl_unlock,
               so_rdknl_assert_lock);
           knlist_init(&so->so_wrsel.si_note, so, so_wrknl_lock, so_wrknl_unlock,
               so_wrknl_assert_lock);
           VNET_SO_ASSERT(head);
           if (soreserve(so, head->sol_sbsnd_hiwat, head->sol_sbrcv_hiwat)) {
                   sodealloc(so);
                   log(LOG_DEBUG, "%s: pcb %p: soreserve() failed\n",
                       __func__, head->so_pcb);
                   return (NULL);
           }
           so->so_rcv.sb_lowat = head->sol_sbrcv_lowat;
           so->so_snd.sb_lowat = head->sol_sbsnd_lowat;
           so->so_rcv.sb_timeo = head->sol_sbrcv_timeo;
           so->so_snd.sb_timeo = head->sol_sbsnd_timeo;
           so->so_rcv.sb_flags = head->sol_sbrcv_flags & SB_AUTOSIZE;
           so->so_snd.sb_flags = head->sol_sbsnd_flags & SB_AUTOSIZE;
           if ((so->so_proto->pr_flags & PR_SOCKBUF) == 0) {
                   so->so_snd.sb_mtx = &so->so_snd_mtx;
                   so->so_rcv.sb_mtx = &so->so_rcv_mtx;
           }
   
           return (so);
   }
   
   /* Connstatus may be 0, or SS_ISCONFIRMING, or SS_ISCONNECTED. */
   struct socket *
   sonewconn(struct socket *head, int connstatus)
   {
           struct socket *so;
   
           if ((so = solisten_clone(head)) == NULL)
                   return (NULL);
   
           if (so->so_proto->pr_attach(so, 0, NULL) != 0) {
                   sodealloc(so);
                   log(LOG_DEBUG, "%s: pcb %p: pr_attach() failed\n",
                       __func__, head->so_pcb);
                   return (NULL);
           }
   
           (void)solisten_enqueue(so, connstatus);
   
           return (so);
   }
   
   /*
    * Enqueue socket cloned by solisten_clone() to the listen queue of the
    * listener it has been cloned from.
    *
    * Return 'true' if socket landed on complete queue, otherwise 'false'.
    */
   bool
   solisten_enqueue(struct socket *so, int connstatus)
   {
           struct socket *head = so->so_listen;
   
           MPASS(refcount_load(&so->so_count) == 0);
           refcount_init(&so->so_count, 1);
   
           SOLISTEN_LOCK(head);
           if (head->sol_accept_filter != NULL)
                   connstatus = 0;
           so->so_state |= connstatus;
           soref(head); /* A socket on (in)complete queue refs head. */
           if (connstatus) {
                   TAILQ_INSERT_TAIL(&head->sol_comp, so, so_list);
                   so->so_qstate = SQ_COMP;
                   head->sol_qlen++;
                   solisten_wakeup(head);  /* unlocks */
                   return (true);
           } else {
                   /*
                    * Keep removing sockets from the head until there's room for
                    * us to insert on the tail.  In pre-locking revisions, this
                    * was a simple if(), but as we could be racing with other
                    * threads and soabort() requires dropping locks, we must
                    * loop waiting for the condition to be true.
                    */
                   while (head->sol_incqlen > head->sol_qlimit) {
                           struct socket *sp;
   
                           sp = TAILQ_FIRST(&head->sol_incomp);
                           TAILQ_REMOVE(&head->sol_incomp, sp, so_list);
                           head->sol_incqlen--;
                           SOCK_LOCK(sp);
                           sp->so_qstate = SQ_NONE;
                           sp->so_listen = NULL;
                           SOCK_UNLOCK(sp);
                           sorele_locked(head);    /* does SOLISTEN_UNLOCK, head stays */
                           soabort(sp);
                           SOLISTEN_LOCK(head);
                   }
                   TAILQ_INSERT_TAIL(&head->sol_incomp, so, so_list);
                   so->so_qstate = SQ_INCOMP;
                   head->sol_incqlen++;
                   SOLISTEN_UNLOCK(head);
                   return (false);
           }
   }
   
   #if defined(SCTP) || defined(SCTP_SUPPORT)
   /*
    * Socket part of sctp_peeloff().  Detach a new socket from an
    * association.  The new socket is returned with a reference.
    *
    * XXXGL: reduce copy-paste with solisten_clone().
    */
   struct socket *
   sopeeloff(struct socket *head)
   {
           struct socket *so;
   
           VNET_ASSERT(head->so_vnet != NULL, ("%s:%d so_vnet is NULL, head=%p",
               __func__, __LINE__, head));
           so = soalloc(head->so_vnet);
           if (so == NULL) {
                   log(LOG_DEBUG, "%s: pcb %p: New socket allocation failure: "
                       "limit reached or out of memory\n",
                       __func__, head->so_pcb);
                   return (NULL);
           }
           so->so_type = head->so_type;
           so->so_options = head->so_options;
           so->so_linger = head->so_linger;
           so->so_state = (head->so_state & SS_NBIO) | SS_ISCONNECTED;
           so->so_fibnum = head->so_fibnum;
           so->so_proto = head->so_proto;
           so->so_cred = crhold(head->so_cred);
   #ifdef MAC
           mac_socket_newconn(head, so);
   #endif
           knlist_init(&so->so_rdsel.si_note, so, so_rdknl_lock, so_rdknl_unlock,
               so_rdknl_assert_lock);
           knlist_init(&so->so_wrsel.si_note, so, so_wrknl_lock, so_wrknl_unlock,
               so_wrknl_assert_lock);
           VNET_SO_ASSERT(head);
           if (soreserve(so, head->so_snd.sb_hiwat, head->so_rcv.sb_hiwat)) {
                   sodealloc(so);
                   log(LOG_DEBUG, "%s: pcb %p: soreserve() failed\n",
                       __func__, head->so_pcb);
                   return (NULL);
           }
           if ((*so->so_proto->pr_attach)(so, 0, NULL)) {
                   sodealloc(so);
                   log(LOG_DEBUG, "%s: pcb %p: pru_attach() failed\n",
                       __func__, head->so_pcb);
                   return (NULL);
           }
           so->so_rcv.sb_lowat = head->so_rcv.sb_lowat;
           so->so_snd.sb_lowat = head->so_snd.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;
   
           soref(so);
   
           return (so);
   }
   #endif  /* SCTP */
   
   int
   sobind(struct socket *so, struct sockaddr *nam, struct thread *td)
   {
           int error;
   
           CURVNET_SET(so->so_vnet);
           error = so->so_proto->pr_bind(so, nam, td);
           CURVNET_RESTORE();
           return (error);
   }
   
   int
   sobindat(int fd, struct socket *so, struct sockaddr *nam, struct thread *td)
   {
           int error;
   
           CURVNET_SET(so->so_vnet);
           error = so->so_proto->pr_bindat(fd, so, nam, td);
           CURVNET_RESTORE();
           return (error);
   }
   
   /*
    * solisten() transitions a socket from a non-listening state to a listening
    * state, but can also be used to update the listen queue depth on an
    * existing listen socket.  The protocol will call back into the sockets
    * layer using solisten_proto_check() and solisten_proto() to check and set
    * socket-layer listen state.  Call backs are used so that the protocol can
    * acquire both protocol and socket layer locks in whatever order is required
    * by the protocol.
    *
    * Protocol implementors are advised to hold the socket lock across the
    * socket-layer test and set to avoid races at the socket layer.
    */
   int
   solisten(struct socket *so, int backlog, struct thread *td)
   {
           int error;
   
           CURVNET_SET(so->so_vnet);
           error = so->so_proto->pr_listen(so, backlog, td);
           CURVNET_RESTORE();
           return (error);
   }
   
   /*
    * Prepare for a call to solisten_proto().  Acquire all socket buffer locks in
    * order to interlock with socket I/O.
    */
   int
   solisten_proto_check(struct socket *so)
   {
           SOCK_LOCK_ASSERT(so);
   
           if ((so->so_state & (SS_ISCONNECTED | SS_ISCONNECTING |
               SS_ISDISCONNECTING)) != 0)
                   return (EINVAL);
   
           /*
            * Sleeping is not permitted here, so simply fail if userspace is
            * attempting to transmit or receive on the socket.  This kind of
            * transient failure is not ideal, but it should occur only if userspace
            * is misusing the socket interfaces.
            */
           if (!sx_try_xlock(&so->so_snd_sx))
                   return (EAGAIN);
           if (!sx_try_xlock(&so->so_rcv_sx)) {
                   sx_xunlock(&so->so_snd_sx);
                   return (EAGAIN);
           }
           mtx_lock(&so->so_snd_mtx);
           mtx_lock(&so->so_rcv_mtx);
   
           /* Interlock with soo_aio_queue(). */
           if (!SOLISTENING(so) &&
              ((so->so_snd.sb_flags & (SB_AIO | SB_AIO_RUNNING)) != 0 ||
              (so->so_rcv.sb_flags & (SB_AIO | SB_AIO_RUNNING)) != 0)) {
                   solisten_proto_abort(so);
                   return (EINVAL);
           }
           return (0);
   }
   
  /*
   * Undo the setup done by solisten_proto_check().
   */
  void
  solisten_proto_abort(struct socket *so)
  {
          mtx_unlock(&so->so_snd_mtx);
          mtx_unlock(&so->so_rcv_mtx);
          sx_xunlock(&so->so_snd_sx);
          sx_xunlock(&so->so_rcv_sx);
  }
  
  void
  solisten_proto(struct socket *so, int backlog)
  {
          int sbrcv_lowat, sbsnd_lowat;
          u_int sbrcv_hiwat, sbsnd_hiwat;
          short sbrcv_flags, sbsnd_flags;
          sbintime_t sbrcv_timeo, sbsnd_timeo;
  
          SOCK_LOCK_ASSERT(so);
          KASSERT((so->so_state & (SS_ISCONNECTED | SS_ISCONNECTING |
              SS_ISDISCONNECTING)) == 0,
              ("%s: bad socket state %p", __func__, so));
  
          if (SOLISTENING(so))
                  goto listening;
  
          /*
           * Change this socket to listening state.
           */
          sbrcv_lowat = so->so_rcv.sb_lowat;
          sbsnd_lowat = so->so_snd.sb_lowat;
          sbrcv_hiwat = so->so_rcv.sb_hiwat;
          sbsnd_hiwat = so->so_snd.sb_hiwat;
          sbrcv_flags = so->so_rcv.sb_flags;
          sbsnd_flags = so->so_snd.sb_flags;
          sbrcv_timeo = so->so_rcv.sb_timeo;
          sbsnd_timeo = so->so_snd.sb_timeo;
  
          sbdestroy(so, SO_SND);
          sbdestroy(so, SO_RCV);
  
  #ifdef INVARIANTS
          bzero(&so->so_rcv,
              sizeof(struct socket) - offsetof(struct socket, so_rcv));
  #endif
  
          so->sol_sbrcv_lowat = sbrcv_lowat;
          so->sol_sbsnd_lowat = sbsnd_lowat;
          so->sol_sbrcv_hiwat = sbrcv_hiwat;
          so->sol_sbsnd_hiwat = sbsnd_hiwat;
          so->sol_sbrcv_flags = sbrcv_flags;
          so->sol_sbsnd_flags = sbsnd_flags;
          so->sol_sbrcv_timeo = sbrcv_timeo;
          so->sol_sbsnd_timeo = sbsnd_timeo;
  
          so->sol_qlen = so->sol_incqlen = 0;
          TAILQ_INIT(&so->sol_incomp);
          TAILQ_INIT(&so->sol_comp);
  
          so->sol_accept_filter = NULL;
          so->sol_accept_filter_arg = NULL;
          so->sol_accept_filter_str = NULL;
  
          so->sol_upcall = NULL;
          so->sol_upcallarg = NULL;
  
          so->so_options |= SO_ACCEPTCONN;
  
  listening:
          if (backlog < 0 || backlog > somaxconn)
                  backlog = somaxconn;
          so->sol_qlimit = backlog;
  
          mtx_unlock(&so->so_snd_mtx);
          mtx_unlock(&so->so_rcv_mtx);
          sx_xunlock(&so->so_snd_sx);
          sx_xunlock(&so->so_rcv_sx);
  }
  
  /*
   * Wakeup listeners/subsystems once we have a complete connection.
   * Enters with lock, returns unlocked.
   */
  void
  solisten_wakeup(struct socket *sol)
  {
  
          if (sol->sol_upcall != NULL)
                  (void )sol->sol_upcall(sol, sol->sol_upcallarg, M_NOWAIT);
          else {
                  selwakeuppri(&sol->so_rdsel, PSOCK);
                  KNOTE_LOCKED(&sol->so_rdsel.si_note, 0);
          }
          SOLISTEN_UNLOCK(sol);
          wakeup_one(&sol->sol_comp);
          if ((sol->so_state & SS_ASYNC) && sol->so_sigio != NULL)
                  pgsigio(&sol->so_sigio, SIGIO, 0);
  }
  
  /*
   * Return single connection off a listening socket queue.  Main consumer of
   * the function is kern_accept4().  Some modules, that do their own accept
   * management also use the function.  The socket reference held by the
   * listen queue is handed to the caller.
   *
   * Listening socket must be locked on entry and is returned unlocked on
   * return.
   * The flags argument is set of accept4(2) flags and ACCEPT4_INHERIT.
   */
  int
  solisten_dequeue(struct socket *head, struct socket **ret, int flags)
  {
          struct socket *so;
          int error;
  
          SOLISTEN_LOCK_ASSERT(head);
  
          while (!(head->so_state & SS_NBIO) && TAILQ_EMPTY(&head->sol_comp) &&
              head->so_error == 0) {
                  error = msleep(&head->sol_comp, SOCK_MTX(head), PSOCK | PCATCH,
                      "accept", 0);
                  if (error != 0) {
                          SOLISTEN_UNLOCK(head);
                          return (error);
                  }
          }
          if (head->so_error) {
                  error = head->so_error;
                  head->so_error = 0;
          } else if ((head->so_state & SS_NBIO) && TAILQ_EMPTY(&head->sol_comp))
                  error = EWOULDBLOCK;
          else
                  error = 0;
          if (error) {
                  SOLISTEN_UNLOCK(head);
                  return (error);
          }
          so = TAILQ_FIRST(&head->sol_comp);
          SOCK_LOCK(so);
          KASSERT(so->so_qstate == SQ_COMP,
              ("%s: so %p not SQ_COMP", __func__, so));
          head->sol_qlen--;
          so->so_qstate = SQ_NONE;
          so->so_listen = NULL;
          TAILQ_REMOVE(&head->sol_comp, so, so_list);
          if (flags & ACCEPT4_INHERIT)
                  so->so_state |= (head->so_state & SS_NBIO);
          else
                  so->so_state |= (flags & SOCK_NONBLOCK) ? SS_NBIO : 0;
          SOCK_UNLOCK(so);
          sorele_locked(head);
  
          *ret = so;
          return (0);
  }
  
  /*
   * Free socket upon release of the very last reference.
   */
  static void
  sofree(struct socket *so)
  {
          struct protosw *pr = so->so_proto;
  
          SOCK_LOCK_ASSERT(so);
          KASSERT(refcount_load(&so->so_count) == 0,
              ("%s: so %p has references", __func__, so));
          KASSERT(SOLISTENING(so) || so->so_qstate == SQ_NONE,
              ("%s: so %p is on listen queue", __func__, so));
  
          SOCK_UNLOCK(so);
  
          if (so->so_dtor != NULL)
                  so->so_dtor(so);
  
          VNET_SO_ASSERT(so);
          if ((pr->pr_flags & PR_RIGHTS) && !SOLISTENING(so)) {
                  MPASS(pr->pr_domain->dom_dispose != NULL);
                  (*pr->pr_domain->dom_dispose)(so);
          }
          if (pr->pr_detach != NULL)
                  pr->pr_detach(so);
  
          /*
           * From this point on, we assume that no other references to this
           * socket exist anywhere else in the stack.  Therefore, no locks need
           * to be acquired or held.
           */
          if (!(pr->pr_flags & PR_SOCKBUF) && !SOLISTENING(so)) {
                  sbdestroy(so, SO_SND);
                  sbdestroy(so, SO_RCV);
          }
          seldrain(&so->so_rdsel);
          seldrain(&so->so_wrsel);
          knlist_destroy(&so->so_rdsel.si_note);
          knlist_destroy(&so->so_wrsel.si_note);
          sodealloc(so);
  }
  
  /*
   * Release a reference on a socket while holding the socket lock.
   * Unlocks the socket lock before returning.
   */
  void
  sorele_locked(struct socket *so)
  {
          SOCK_LOCK_ASSERT(so);
          if (refcount_release(&so->so_count))
                  sofree(so);
          else
                  SOCK_UNLOCK(so);
  }
  
  /*
   * Close a socket on last file table reference removal.  Initiate disconnect
   * if connected.  Free socket when disconnect complete.
   *
   * This function will sorele() the socket.  Note that soclose() may be called
   * prior to the ref count reaching zero.  The actual socket structure will
   * not be freed until the ref count reaches zero.
   */
  int
  soclose(struct socket *so)
  {
          struct accept_queue lqueue;
          int error = 0;
          bool listening, last __diagused;
  
          CURVNET_SET(so->so_vnet);
          funsetown(&so->so_sigio);
          if (so->so_state & SS_ISCONNECTED) {
                  if ((so->so_state & SS_ISDISCONNECTING) == 0) {
                          error = sodisconnect(so);
                          if (error) {
                                  if (error == ENOTCONN)
                                          error = 0;
                                  goto drop;
                          }
                  }
  
                  if ((so->so_options & SO_LINGER) != 0 && so->so_linger != 0) {
                          if ((so->so_state & SS_ISDISCONNECTING) &&
                              (so->so_state & SS_NBIO))
                                  goto drop;
                          while (so->so_state & SS_ISCONNECTED) {
                                  error = tsleep(&so->so_timeo,
                                      PSOCK | PCATCH, "soclos",
                                      so->so_linger * hz);
                                  if (error)
                                          break;
                          }
                  }
          }
  
  drop:
          if (so->so_proto->pr_close != NULL)
                  so->so_proto->pr_close(so);
  
          SOCK_LOCK(so);
          if ((listening = SOLISTENING(so))) {
                  struct socket *sp;
  
                  TAILQ_INIT(&lqueue);
                  TAILQ_SWAP(&lqueue, &so->sol_incomp, socket, so_list);
                  TAILQ_CONCAT(&lqueue, &so->sol_comp, so_list);
  
                  so->sol_qlen = so->sol_incqlen = 0;
  
                  TAILQ_FOREACH(sp, &lqueue, so_list) {
                          SOCK_LOCK(sp);
                          sp->so_qstate = SQ_NONE;
                          sp->so_listen = NULL;
                          SOCK_UNLOCK(sp);
                          last = refcount_release(&so->so_count);
                          KASSERT(!last, ("%s: released last reference for %p",
                              __func__, so));
                  }
          }
          sorele_locked(so);
          if (listening) {
                  struct socket *sp, *tsp;
  
                  TAILQ_FOREACH_SAFE(sp, &lqueue, so_list, tsp)
                          soabort(sp);
          }
          CURVNET_RESTORE();
          return (error);
  }
  
  /*
   * soabort() is used to abruptly tear down a connection, such as when a
   * resource limit is reached (listen queue depth exceeded), or if a listen
   * socket is closed while there are sockets waiting to be accepted.
   *
   * This interface is tricky, because it is called on an unreferenced socket,
   * and must be called only by a thread that has actually removed the socket
   * from the listen queue it was on.  Likely this thread holds the last
   * reference on the socket and soabort() will proceed with sofree().  But
   * it might be not the last, as the sockets on the listen queues are seen
   * from the protocol side.
   *
   * This interface will call into the protocol code, so must not be called
   * with any socket locks held.  Protocols do call it while holding their own
   * recursible protocol mutexes, but this is something that should be subject
   * to review in the future.
   *
   * Usually socket should have a single reference left, but this is not a
   * requirement.  In the past, when we have had named references for file
   * descriptor and protocol, we asserted that none of them are being held.
   */
  void
  soabort(struct socket *so)
  {
  
          VNET_SO_ASSERT(so);
  
          if (so->so_proto->pr_abort != NULL)
                  so->so_proto->pr_abort(so);
          SOCK_LOCK(so);
          sorele_locked(so);
  }
  
  int
  soaccept(struct socket *so, struct sockaddr **nam)
  {
          int error;
  
          CURVNET_SET(so->so_vnet);
          error = so->so_proto->pr_accept(so, nam);
          CURVNET_RESTORE();
          return (error);
  }
  
  int
  soconnect(struct socket *so, struct sockaddr *nam, struct thread *td)
  {
  
          return (soconnectat(AT_FDCWD, so, nam, td));
  }
  
  int
  soconnectat(int fd, struct socket *so, struct sockaddr *nam, struct thread *td)
  {
          int error;
  
          CURVNET_SET(so->so_vnet);
          /*
           * If protocol is connection-based, can only connect once.
           * Otherwise, if connected, try to disconnect first.  This allows
           * user to disconnect by connecting to, e.g., a null address.
           */
          if (so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING) &&
              ((so->so_proto->pr_flags & PR_CONNREQUIRED) ||
              (error = sodisconnect(so)))) {
                  error = EISCONN;
          } else {
                  /*
                   * Prevent accumulated error from previous connection from
                   * biting us.
                   */
                  so->so_error = 0;
                  if (fd == AT_FDCWD) {
                          error = so->so_proto->pr_connect(so, nam, td);
                  } else {
                          error = so->so_proto->pr_connectat(fd, so, nam, td);
                  }
          }
          CURVNET_RESTORE();
  
          return (error);
  }
  
  int
  soconnect2(struct socket *so1, struct socket *so2)
  {
          int error;
  
          CURVNET_SET(so1->so_vnet);
          error = so1->so_proto->pr_connect2(so1, so2);
          CURVNET_RESTORE();
          return (error);
  }
  
  int
  sodisconnect(struct socket *so)
  {
          int error;
  
          if ((so->so_state & SS_ISCONNECTED) == 0)
                  return (ENOTCONN);
          if (so->so_state & SS_ISDISCONNECTING)
                  return (EALREADY);
          VNET_SO_ASSERT(so);
          error = so->so_proto->pr_disconnect(so);
          return (error);
  }
  
  int
  sosend_dgram(struct socket *so, struct sockaddr *addr, struct uio *uio,
      struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
  {
          long space;
          ssize_t resid;
          int clen = 0, error, dontroute;
  
          KASSERT(so->so_type == SOCK_DGRAM, ("sosend_dgram: !SOCK_DGRAM"));
          KASSERT(so->so_proto->pr_flags & PR_ATOMIC,
              ("sosend_dgram: !PR_ATOMIC"));
  
          if (uio != NULL)
                  resid = uio->uio_resid;
          else
                  resid = top->m_pkthdr.len;
          /*
           * In theory resid should be unsigned.  However, space must be
           * signed, as it might be less than 0 if we over-committed, and we
           * must use a signed comparison of space and resid.  On the other
           * hand, a negative resid causes us to loop sending 0-length
           * segments to the protocol.
           */
          if (resid < 0) {
                  error = EINVAL;
                  goto out;
          }
  
          dontroute =
              (flags & MSG_DONTROUTE) && (so->so_options & SO_DONTROUTE) == 0;
          if (td != NULL)
                  td->td_ru.ru_msgsnd++;
          if (control != NULL)
                  clen = control->m_len;
  
          SOCKBUF_LOCK(&so->so_snd);
          if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
                  SOCKBUF_UNLOCK(&so->so_snd);
                  error = EPIPE;
                  goto out;
          }
          if (so->so_error) {
                  error = so->so_error;
                  so->so_error = 0;
                  SOCKBUF_UNLOCK(&so->so_snd);
                  goto out;
          }
          if ((so->so_state & SS_ISCONNECTED) == 0) {
                  /*
                   * `sendto' and `sendmsg' is allowed on a connection-based
                   * socket if it supports implied connect.  Return ENOTCONN if
                   * not connected and no address is supplied.
                   */
                  if ((so->so_proto->pr_flags & PR_CONNREQUIRED) &&
                      (so->so_proto->pr_flags & PR_IMPLOPCL) == 0) {
                          if ((so->so_state & SS_ISCONFIRMING) == 0 &&
                              !(resid == 0 && clen != 0)) {
                                  SOCKBUF_UNLOCK(&so->so_snd);
                                  error = ENOTCONN;
                                  goto out;
                          }
                  } else if (addr == NULL) {
                          if (so->so_proto->pr_flags & PR_CONNREQUIRED)
                                  error = ENOTCONN;
                          else
                                  error = EDESTADDRREQ;
                          SOCKBUF_UNLOCK(&so->so_snd);
                          goto out;
                  }
          }
  
          /*
           * Do we need MSG_OOB support in SOCK_DGRAM?  Signs here may be a
           * problem and need fixing.
           */
          space = sbspace(&so->so_snd);
          if (flags & MSG_OOB)
                  space += 1024;
          space -= clen;
          SOCKBUF_UNLOCK(&so->so_snd);
          if (resid > space) {
                  error = EMSGSIZE;
                  goto out;
          }
          if (uio == NULL) {
                  resid = 0;
                  if (flags & MSG_EOR)
                          top->m_flags |= M_EOR;
          } else {
                  /*
                   * Copy the data from userland into a mbuf chain.
                   * If no data is to be copied in, a single empty mbuf
                   * is returned.
                   */
                  top = m_uiotombuf(uio, M_WAITOK, space, max_hdr,
                      (M_PKTHDR | ((flags & MSG_EOR) ? M_EOR : 0)));
                  if (top == NULL) {
                          error = EFAULT; /* only possible error */
                          goto out;
                  }
                  space -= resid - uio->uio_resid;
                  resid = uio->uio_resid;
          }
          KASSERT(resid == 0, ("sosend_dgram: resid != 0"));
          /*
           * XXXRW: Frobbing SO_DONTROUTE here is even worse without sblock
           * than with.
           */
          if (dontroute) {
                  SOCK_LOCK(so);
                  so->so_options |= SO_DONTROUTE;
                  SOCK_UNLOCK(so);
          }
          /*
           * XXX all the SBS_CANTSENDMORE checks previously done could be out
           * of date.  We could have received a reset packet in an interrupt or
           * maybe we slept while doing page faults in uiomove() etc.  We could
           * probably recheck again inside the locking protection here, but
           * there are probably other places that this also happens.  We must
           * rethink this.
           */
          VNET_SO_ASSERT(so);
          error = so->so_proto->pr_send(so, (flags & MSG_OOB) ? PRUS_OOB :
          /*
           * If the user set MSG_EOF, the protocol understands this flag and
           * nothing left to send then use PRU_SEND_EOF instead of PRU_SEND.
           */
              ((flags & MSG_EOF) &&
               (so->so_proto->pr_flags & PR_IMPLOPCL) &&
               (resid <= 0)) ?
                  PRUS_EOF :
                  /* If there is more to send set PRUS_MORETOCOME */
                  (flags & MSG_MORETOCOME) ||
                  (resid > 0 && space > 0) ? PRUS_MORETOCOME : 0,
                  top, addr, control, td);
          if (dontroute) {
                  SOCK_LOCK(so);
                  so->so_options &= ~SO_DONTROUTE;
                  SOCK_UNLOCK(so);
          }
          clen = 0;
          control = NULL;
          top = NULL;
  out:
          if (top != NULL)
                  m_freem(top);
          if (control != NULL)
                  m_freem(control);
          return (error);
  }
  
  /*
   * Send on a socket.  If send must go all at once and message is larger than
   * send buffering, then hard error.  Lock against other senders.  If must go
   * all at once and not enough room now, then inform user that this would
   * block and do nothing.  Otherwise, if nonblocking, send as much as
   * possible.  The data to be sent is described by "uio" if nonzero, otherwise
   * by the mbuf chain "top" (which must be null if uio is not).  Data provided
   * in mbuf chain must be small enough to send all at once.
   *
   * Returns nonzero on error, timeout or signal; callers must check for short
   * counts if EINTR/ERESTART are returned.  Data and control buffers are freed
   * on return.
   */
  int
  sosend_generic(struct socket *so, struct sockaddr *addr, struct uio *uio,
      struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
  {
          long space;
          ssize_t resid;
          int clen = 0, error, dontroute;
          int atomic = sosendallatonce(so) || top;
          int pr_send_flag;
  #ifdef KERN_TLS
          struct ktls_session *tls;
          int tls_enq_cnt, tls_send_flag;
          uint8_t tls_rtype;
  
          tls = NULL;
          tls_rtype = TLS_RLTYPE_APP;
  #endif
          if (uio != NULL)
                  resid = uio->uio_resid;
          else if ((top->m_flags & M_PKTHDR) != 0)
                  resid = top->m_pkthdr.len;
          else
                  resid = m_length(top, NULL);
          /*
           * In theory resid should be unsigned.  However, space must be
           * signed, as it might be less than 0 if we over-committed, and we
           * must use a signed comparison of space and resid.  On the other
           * hand, a negative resid causes us to loop sending 0-length
           * segments to the protocol.
           *
           * Also check to make sure that MSG_EOR isn't used on SOCK_STREAM
           * type sockets since that's an error.
           */
          if (resid < 0 || (so->so_type == SOCK_STREAM && (flags & MSG_EOR))) {
                  error = EINVAL;
                  goto out;
          }
  
          dontroute =
              (flags & MSG_DONTROUTE) && (so->so_options & SO_DONTROUTE) == 0 &&
              (so->so_proto->pr_flags & PR_ATOMIC);
          if (td != NULL)
                  td->td_ru.ru_msgsnd++;
          if (control != NULL)
                  clen = control->m_len;
  
          error = SOCK_IO_SEND_LOCK(so, SBLOCKWAIT(flags));
          if (error)
                  goto out;
  
  #ifdef KERN_TLS
          tls_send_flag = 0;
          tls = ktls_hold(so->so_snd.sb_tls_info);
          if (tls != NULL) {
                  if (tls->mode == TCP_TLS_MODE_SW)
                          tls_send_flag = PRUS_NOTREADY;
  
                  if (control != NULL) {
                          struct cmsghdr *cm = mtod(control, struct cmsghdr *);
  
                          if (clen >= sizeof(*cm) &&
                              cm->cmsg_type == TLS_SET_RECORD_TYPE) {
                                  tls_rtype = *((uint8_t *)CMSG_DATA(cm));
                                  clen = 0;
                                  m_freem(control);
                                  control = NULL;
                                  atomic = 1;
                          }
                  }
  
                  if (resid == 0 && !ktls_permit_empty_frames(tls)) {
                          error = EINVAL;
                          goto release;
                  }
          }
  #endif
  
  restart:
          do {
                  SOCKBUF_LOCK(&so->so_snd);
                  if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
                          SOCKBUF_UNLOCK(&so->so_snd);
                          error = EPIPE;
                          goto release;
                  }
                  if (so->so_error) {
                          error = so->so_error;
                          so->so_error = 0;
                          SOCKBUF_UNLOCK(&so->so_snd);
                          goto release;
                  }
                  if ((so->so_state & SS_ISCONNECTED) == 0) {
                          /*
                           * `sendto' and `sendmsg' is allowed on a connection-
                           * based socket if it supports implied connect.
                           * Return ENOTCONN if not connected and no address is
                           * supplied.
                           */
                          if ((so->so_proto->pr_flags & PR_CONNREQUIRED) &&
                              (so->so_proto->pr_flags & PR_IMPLOPCL) == 0) {
                                  if ((so->so_state & SS_ISCONFIRMING) == 0 &&
                                      !(resid == 0 && clen != 0)) {
                                          SOCKBUF_UNLOCK(&so->so_snd);
                                          error = ENOTCONN;
                                          goto release;
                                  }
                          } else if (addr == NULL) {
                                  SOCKBUF_UNLOCK(&so->so_snd);
                                  if (so->so_proto->pr_flags & PR_CONNREQUIRED)
                                          error = ENOTCONN;
                                  else
                                          error = EDESTADDRREQ;
                                  goto release;
                          }
                  }
                  space = sbspace(&so->so_snd);
                  if (flags & MSG_OOB)
                          space += 1024;
                  if ((atomic && resid > so->so_snd.sb_hiwat) ||
                      clen > so->so_snd.sb_hiwat) {
                          SOCKBUF_UNLOCK(&so->so_snd);
                          error = EMSGSIZE;
                          goto release;
                  }
                  if (space < resid + clen &&
                      (atomic || space < so->so_snd.sb_lowat || space < clen)) {
                          if ((so->so_state & SS_NBIO) ||
                              (flags & (MSG_NBIO | MSG_DONTWAIT)) != 0) {
                                  SOCKBUF_UNLOCK(&so->so_snd);
                                  error = EWOULDBLOCK;
                                  goto release;
                          }
                          error = sbwait(so, SO_SND);
                          SOCKBUF_UNLOCK(&so->so_snd);
                          if (error)
                                  goto release;
                          goto restart;
                  }
                  SOCKBUF_UNLOCK(&so->so_snd);
                  space -= clen;
                  do {
                          if (uio == NULL) {
                                  resid = 0;
                                  if (flags & MSG_EOR)
                                          top->m_flags |= M_EOR;
  #ifdef KERN_TLS
                                  if (tls != NULL) {
                                          ktls_frame(top, tls, &tls_enq_cnt,
                                              tls_rtype);
                                          tls_rtype = TLS_RLTYPE_APP;
                                  }
  #endif
                          } else {
                                  /*
                                   * Copy the data from userland into a mbuf
                                   * chain.  If resid is 0, which can happen
                                   * only if we have control to send, then
                                   * a single empty mbuf is returned.  This
                                   * is a workaround to prevent protocol send
                                   * methods to panic.
                                   */
  #ifdef KERN_TLS
                                  if (tls != NULL) {
                                          top = m_uiotombuf(uio, M_WAITOK, space,
                                              tls->params.max_frame_len,
                                              M_EXTPG |
                                              ((flags & MSG_EOR) ? M_EOR : 0));
                                          if (top != NULL) {
                                                  ktls_frame(top, tls,
                                                      &tls_enq_cnt, tls_rtype);
                                          }
                                          tls_rtype = TLS_RLTYPE_APP;
                                  } else
  #endif
                                          top = m_uiotombuf(uio, M_WAITOK, space,
                                              (atomic ? max_hdr : 0),
                                              (atomic ? M_PKTHDR : 0) |
                                              ((flags & MSG_EOR) ? M_EOR : 0));
                                  if (top == NULL) {
                                          error = EFAULT; /* only possible error */
                                          goto release;
                                  }
                                  space -= resid - uio->uio_resid;
                                  resid = uio->uio_resid;
                          }
                          if (dontroute) {
                                  SOCK_LOCK(so);
                                  so->so_options |= SO_DONTROUTE;
                                  SOCK_UNLOCK(so);
                          }
                          /*
                           * XXX all the SBS_CANTSENDMORE checks previously
                           * done could be out of date.  We could have received
                           * a reset packet in an interrupt or maybe we slept
                           * while doing page faults in uiomove() etc.  We
                           * could probably recheck again inside the locking
                           * protection here, but there are probably other
                           * places that this also happens.  We must rethink
                           * this.
                           */
                          VNET_SO_ASSERT(so);
  
                          pr_send_flag = (flags & MSG_OOB) ? PRUS_OOB :
                          /*
                           * If the user set MSG_EOF, the protocol understands
                           * this flag and nothing left to send then use
                           * PRU_SEND_EOF instead of PRU_SEND.
                           */
                              ((flags & MSG_EOF) &&
                               (so->so_proto->pr_flags & PR_IMPLOPCL) &&
                               (resid <= 0)) ?
                                  PRUS_EOF :
                          /* If there is more to send set PRUS_MORETOCOME. */
                              (flags & MSG_MORETOCOME) ||
                              (resid > 0 && space > 0) ? PRUS_MORETOCOME : 0;
  
  #ifdef KERN_TLS
                          pr_send_flag |= tls_send_flag;
  #endif
  
                          error = so->so_proto->pr_send(so, pr_send_flag, top,
                              addr, control, td);
  
                          if (dontroute) {
                                  SOCK_LOCK(so);
                                  so->so_options &= ~SO_DONTROUTE;
                                  SOCK_UNLOCK(so);
                          }
  
  #ifdef KERN_TLS
                          if (tls != NULL && tls->mode == TCP_TLS_MODE_SW) {
                                  if (error != 0) {
                                          m_freem(top);
                                          top = NULL;
                                  } else {
                                          soref(so);
                                          ktls_enqueue(top, so, tls_enq_cnt);
                                  }
                          }
  #endif
                          clen = 0;
                          control = NULL;
                          top = NULL;
                          if (error)
                                  goto release;
                  } while (resid && space > 0);
          } while (resid);
  
  release:
          SOCK_IO_SEND_UNLOCK(so);
  out:
  #ifdef KERN_TLS
          if (tls != NULL)
                  ktls_free(tls);
  #endif
          if (top != NULL)
                  m_freem(top);
          if (control != NULL)
                  m_freem(control);
          return (error);
  }
  
  /*
   * Send to a socket from a kernel thread.
   *
   * XXXGL: in almost all cases uio is NULL and the mbuf is supplied.
   * Exception is nfs/bootp_subr.c.  It is arguable that the VNET context needs
   * to be set at all.  This function should just boil down to a static inline
   * calling the protocol method.
   */
  int
  sosend(struct socket *so, struct sockaddr *addr, struct uio *uio,
      struct mbuf *top, struct mbuf *control, int flags, struct thread *td)
  {
          int error;
  
          CURVNET_SET(so->so_vnet);
          error = so->so_proto->pr_sosend(so, addr, uio,
              top, control, flags, td);
          CURVNET_RESTORE();
          return (error);
  }
  
  /*
   * send(2), write(2) or aio_write(2) on a socket.
   */
  int
  sousrsend(struct socket *so, struct sockaddr *addr, struct uio *uio,
      struct mbuf *control, int flags, struct proc *userproc)
  {
          struct thread *td;
          ssize_t len;
          int error;
  
          td = uio->uio_td;
          len = uio->uio_resid;
          CURVNET_SET(so->so_vnet);
          error = so->so_proto->pr_sosend(so, addr, uio, NULL, control, flags,
              td);
          CURVNET_RESTORE();
          if (error != 0) {
                  if (uio->uio_resid != len &&
                      (so->so_proto->pr_flags & PR_ATOMIC) == 0 &&
                      (error == ERESTART || error == EINTR ||
                      error == EWOULDBLOCK))
                          error = 0;
                  /* Generation of SIGPIPE can be controlled per socket. */
                  if (error == EPIPE && (so->so_options & SO_NOSIGPIPE) == 0 &&
                      (flags & MSG_NOSIGNAL) == 0) {
                          if (userproc != NULL) {
                                  /* aio(4) job */
                                  PROC_LOCK(userproc);
                                  kern_psignal(userproc, SIGPIPE);
                                  PROC_UNLOCK(userproc);
                          } else {
                                  PROC_LOCK(td->td_proc);
                                  tdsignal(td, SIGPIPE);
                                  PROC_UNLOCK(td->td_proc);
                          }
                  }
          }
          return (error);
  }
  
  /*
   * The part of soreceive() that implements reading non-inline out-of-band
   * data from a socket.  For more complete comments, see soreceive(), from
   * which this code originated.
   *
   * Note that soreceive_rcvoob(), unlike the remainder of soreceive(), is
   * unable to return an mbuf chain to the caller.
   */
  static int
  soreceive_rcvoob(struct socket *so, struct uio *uio, int flags)
  {
          struct protosw *pr = so->so_proto;
          struct mbuf *m;
          int error;
  
          KASSERT(flags & MSG_OOB, ("soreceive_rcvoob: (flags & MSG_OOB) == 0"));
          VNET_SO_ASSERT(so);
  
          m = m_get(M_WAITOK, MT_DATA);
          error = pr->pr_rcvoob(so, m, flags & MSG_PEEK);
          if (error)
                  goto bad;
          do {
                  error = uiomove(mtod(m, void *),
                      (int) min(uio->uio_resid, m->m_len), uio);
                  m = m_free(m);
          } while (uio->uio_resid && error == 0 && m);
  bad:
          if (m != NULL)
                  m_freem(m);
          return (error);
  }
  
  /*
   * Following replacement or removal of the first mbuf on the first mbuf chain
   * of a socket buffer, push necessary state changes back into the socket
   * buffer so that other consumers see the values consistently.  'nextrecord'
   * is the callers locally stored value of the original value of
   * sb->sb_mb->m_nextpkt which must be restored when the lead mbuf changes.
   * NOTE: 'nextrecord' may be NULL.
   */
  static __inline void
  sockbuf_pushsync(struct sockbuf *sb, struct mbuf *nextrecord)
  {
  
          SOCKBUF_LOCK_ASSERT(sb);
          /*
           * First, update for the new value of nextrecord.  If necessary, make
           * it the first record.
           */
          if (sb->sb_mb != NULL)
                  sb->sb_mb->m_nextpkt = nextrecord;
          else
                  sb->sb_mb = nextrecord;
  
          /*
           * Now update any dependent socket buffer fields to reflect the new
           * state.  This is an expanded inline of SB_EMPTY_FIXUP(), with the
           * addition of a second clause that takes care of the case where
           * sb_mb has been updated, but remains the last record.
           */
          if (sb->sb_mb == NULL) {
                  sb->sb_mbtail = NULL;
                  sb->sb_lastrecord = NULL;
          } else if (sb->sb_mb->m_nextpkt == NULL)
                  sb->sb_lastrecord = sb->sb_mb;
  }
  
  /*
   * Implement receive operations on a socket.  We depend on the way that
   * records are added to the sockbuf by sbappend.  In particular, each record
   * (mbufs linked through m_next) must begin with an address if the protocol
   * so specifies, followed by an optional mbuf or mbufs containing ancillary
   * data, and then zero or more mbufs of data.  In order to allow parallelism
   * between network receive and copying to user space, as well as avoid
   * sleeping with a mutex held, we release the socket buffer mutex during the
   * user space copy.  Although the sockbuf is locked, new data may still be
   * appended, and thus we must maintain consistency of the sockbuf during that
   * time.
   *
   * The caller may receive the data as a single mbuf chain by supplying an
   * mbuf **mp0 for use in returning the chain.  The uio is then used only for
   * the count in uio_resid.
   */
  int
  soreceive_generic(struct socket *so, struct sockaddr **psa, struct uio *uio,
      struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
  {
          struct mbuf *m, **mp;
          int flags, error, offset;
          ssize_t len;
          struct protosw *pr = so->so_proto;
          struct mbuf *nextrecord;
          int moff, type = 0;
          ssize_t orig_resid = uio->uio_resid;
          bool report_real_len = false;
  
          mp = mp0;
          if (psa != NULL)
                  *psa = NULL;
          if (controlp != NULL)
                  *controlp = NULL;
          if (flagsp != NULL) {
                  report_real_len = *flagsp & MSG_TRUNC;
                  *flagsp &= ~MSG_TRUNC;
                  flags = *flagsp &~ MSG_EOR;
          } else
                  flags = 0;
          if (flags & MSG_OOB)
                  return (soreceive_rcvoob(so, uio, flags));
          if (mp != NULL)
                  *mp = NULL;
          if ((pr->pr_flags & PR_WANTRCVD) && (so->so_state & SS_ISCONFIRMING)
              && uio->uio_resid) {
                  VNET_SO_ASSERT(so);
                  pr->pr_rcvd(so, 0);
          }
  
          error = SOCK_IO_RECV_LOCK(so, SBLOCKWAIT(flags));
          if (error)
                  return (error);
  
  restart:
          SOCKBUF_LOCK(&so->so_rcv);
          m = so->so_rcv.sb_mb;
          /*
           * If we have less data than requested, block awaiting more (subject
           * to any timeout) if:
           *   1. the current count is less than the low water mark, or
           *   2. MSG_DONTWAIT is not set
           */
          if (m == NULL || (((flags & MSG_DONTWAIT) == 0 &&
              sbavail(&so->so_rcv) < uio->uio_resid) &&
              sbavail(&so->so_rcv) < so->so_rcv.sb_lowat &&
              m->m_nextpkt == NULL && (pr->pr_flags & PR_ATOMIC) == 0)) {
                  KASSERT(m != NULL || !sbavail(&so->so_rcv),
                      ("receive: m == %p sbavail == %u",
                      m, sbavail(&so->so_rcv)));
                  if (so->so_error || so->so_rerror) {
                          if (m != NULL)
                                  goto dontblock;
                          if (so->so_error)
                                  error = so->so_error;
                          else
                                  error = so->so_rerror;
                          if ((flags & MSG_PEEK) == 0) {
                                  if (so->so_error)
                                          so->so_error = 0;
                                  else
                                          so->so_rerror = 0;
                          }
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          goto release;
                  }
                  SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                  if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
                          if (m != NULL)
                                  goto dontblock;
  #ifdef KERN_TLS
                          else if (so->so_rcv.sb_tlsdcc == 0 &&
                              so->so_rcv.sb_tlscc == 0) {
  #else
                          else {
  #endif
                                  SOCKBUF_UNLOCK(&so->so_rcv);
                                  goto release;
                          }
                  }
                  for (; m != NULL; m = m->m_next)
                          if (m->m_type == MT_OOBDATA  || (m->m_flags & M_EOR)) {
                                  m = so->so_rcv.sb_mb;
                                  goto dontblock;
                          }
                  if ((so->so_state & (SS_ISCONNECTING | SS_ISCONNECTED |
                      SS_ISDISCONNECTING | SS_ISDISCONNECTED)) == 0 &&
                      (so->so_proto->pr_flags & PR_CONNREQUIRED) != 0) {
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          error = ENOTCONN;
                          goto release;
                  }
                  if (uio->uio_resid == 0 && !report_real_len) {
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          goto release;
                  }
                  if ((so->so_state & SS_NBIO) ||
                      (flags & (MSG_DONTWAIT|MSG_NBIO))) {
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          error = EWOULDBLOCK;
                          goto release;
                  }
                  SBLASTRECORDCHK(&so->so_rcv);
                  SBLASTMBUFCHK(&so->so_rcv);
                  error = sbwait(so, SO_RCV);
                  SOCKBUF_UNLOCK(&so->so_rcv);
                  if (error)
                          goto release;
                  goto restart;
          }
  dontblock:
          /*
           * From this point onward, we maintain 'nextrecord' as a cache of the
           * pointer to the next record in the socket buffer.  We must keep the
           * various socket buffer pointers and local stack versions of the
           * pointers in sync, pushing out modifications before dropping the
           * socket buffer mutex, and re-reading them when picking it up.
           *
           * Otherwise, we will race with the network stack appending new data
           * or records onto the socket buffer by using inconsistent/stale
           * versions of the field, possibly resulting in socket buffer
           * corruption.
           *
           * By holding the high-level sblock(), we prevent simultaneous
           * readers from pulling off the front of the socket buffer.
           */
          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
          if (uio->uio_td)
                  uio->uio_td->td_ru.ru_msgrcv++;
          KASSERT(m == so->so_rcv.sb_mb, ("soreceive: m != so->so_rcv.sb_mb"));
          SBLASTRECORDCHK(&so->so_rcv);
          SBLASTMBUFCHK(&so->so_rcv);
          nextrecord = m->m_nextpkt;
          if (pr->pr_flags & PR_ADDR) {
                  KASSERT(m->m_type == MT_SONAME,
                      ("m->m_type == %d", m->m_type));
                  orig_resid = 0;
                  if (psa != NULL)
                          *psa = sodupsockaddr(mtod(m, struct sockaddr *),
                              M_NOWAIT);
                  if (flags & MSG_PEEK) {
                          m = m->m_next;
                  } else {
                          sbfree(&so->so_rcv, m);
                          so->so_rcv.sb_mb = m_free(m);
                          m = so->so_rcv.sb_mb;
                          sockbuf_pushsync(&so->so_rcv, nextrecord);
                  }
          }
  
          /*
           * Process one or more MT_CONTROL mbufs present before any data mbufs
           * in the first mbuf chain on the socket buffer.  If MSG_PEEK, we
           * just copy the data; if !MSG_PEEK, we call into the protocol to
           * perform externalization (or freeing if controlp == NULL).
           */
          if (m != NULL && m->m_type == MT_CONTROL) {
                  struct mbuf *cm = NULL, *cmn;
                  struct mbuf **cme = &cm;
  #ifdef KERN_TLS
                  struct cmsghdr *cmsg;
                  struct tls_get_record tgr;
  
                  /*
                   * For MSG_TLSAPPDATA, check for an alert record.
                   * If found, return ENXIO without removing
                   * it from the receive queue.  This allows a subsequent
                   * call without MSG_TLSAPPDATA to receive it.
                   * Note that, for TLS, there should only be a single
                   * control mbuf with the TLS_GET_RECORD message in it.
                   */
                  if (flags & MSG_TLSAPPDATA) {
                          cmsg = mtod(m, struct cmsghdr *);
                          if (cmsg->cmsg_type == TLS_GET_RECORD &&
                              cmsg->cmsg_len == CMSG_LEN(sizeof(tgr))) {
                                  memcpy(&tgr, CMSG_DATA(cmsg), sizeof(tgr));
                                  if (__predict_false(tgr.tls_type ==
                                      TLS_RLTYPE_ALERT)) {
                                          SOCKBUF_UNLOCK(&so->so_rcv);
                                          error = ENXIO;
                                          goto release;
                                  }
                          }
                  }
  #endif
  
                  do {
                          if (flags & MSG_PEEK) {
                                  if (controlp != NULL) {
                                          *controlp = m_copym(m, 0, m->m_len,
                                              M_NOWAIT);
                                          controlp = &(*controlp)->m_next;
                                  }
                                  m = m->m_next;
                          } else {
                                  sbfree(&so->so_rcv, m);
                                  so->so_rcv.sb_mb = m->m_next;
                                  m->m_next = NULL;
                                  *cme = m;
                                  cme = &(*cme)->m_next;
                                  m = so->so_rcv.sb_mb;
                          }
                  } while (m != NULL && m->m_type == MT_CONTROL);
                  if ((flags & MSG_PEEK) == 0)
                          sockbuf_pushsync(&so->so_rcv, nextrecord);
                  while (cm != NULL) {
                          cmn = cm->m_next;
                          cm->m_next = NULL;
                          if (pr->pr_domain->dom_externalize != NULL) {
                                  SOCKBUF_UNLOCK(&so->so_rcv);
                                  VNET_SO_ASSERT(so);
                                  error = (*pr->pr_domain->dom_externalize)
                                      (cm, controlp, flags);
                                  SOCKBUF_LOCK(&so->so_rcv);
                          } else if (controlp != NULL)
                                  *controlp = cm;
                          else
                                  m_freem(cm);
                          if (controlp != NULL) {
                                  while (*controlp != NULL)
                                          controlp = &(*controlp)->m_next;
                          }
                          cm = cmn;
                  }
                  if (m != NULL)
                          nextrecord = so->so_rcv.sb_mb->m_nextpkt;
                  else
                          nextrecord = so->so_rcv.sb_mb;
                  orig_resid = 0;
          }
          if (m != NULL) {
                  if ((flags & MSG_PEEK) == 0) {
                          KASSERT(m->m_nextpkt == nextrecord,
                              ("soreceive: post-control, nextrecord !sync"));
                          if (nextrecord == NULL) {
                                  KASSERT(so->so_rcv.sb_mb == m,
                                      ("soreceive: post-control, sb_mb!=m"));
                                  KASSERT(so->so_rcv.sb_lastrecord == m,
                                      ("soreceive: post-control, lastrecord!=m"));
                          }
                  }
                  type = m->m_type;
                  if (type == MT_OOBDATA)
                          flags |= MSG_OOB;
          } else {
                  if ((flags & MSG_PEEK) == 0) {
                          KASSERT(so->so_rcv.sb_mb == nextrecord,
                              ("soreceive: sb_mb != nextrecord"));
                          if (so->so_rcv.sb_mb == NULL) {
                                  KASSERT(so->so_rcv.sb_lastrecord == NULL,
                                      ("soreceive: sb_lastercord != NULL"));
                          }
                  }
          }
          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
          SBLASTRECORDCHK(&so->so_rcv);
          SBLASTMBUFCHK(&so->so_rcv);
  
          /*
           * Now continue to read any data mbufs off of the head of the socket
           * buffer until the read request is satisfied.  Note that 'type' is
           * used to store the type of any mbuf reads that have happened so far
           * such that soreceive() can stop reading if the type changes, which
           * causes soreceive() to return only one of regular data and inline
           * out-of-band data in a single socket receive operation.
           */
          moff = 0;
          offset = 0;
          while (m != NULL && !(m->m_flags & M_NOTAVAIL) && uio->uio_resid > 0
              && error == 0) {
                  /*
                   * If the type of mbuf has changed since the last mbuf
                   * examined ('type'), end the receive operation.
                   */
                  SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                  if (m->m_type == MT_OOBDATA || m->m_type == MT_CONTROL) {
                          if (type != m->m_type)
                                  break;
                  } else if (type == MT_OOBDATA)
                          break;
                  else
                      KASSERT(m->m_type == MT_DATA,
                          ("m->m_type == %d", m->m_type));
                  so->so_rcv.sb_state &= ~SBS_RCVATMARK;
                  len = uio->uio_resid;
                  if (so->so_oobmark && len > so->so_oobmark - offset)
                          len = so->so_oobmark - offset;
                  if (len > m->m_len - moff)
                          len = m->m_len - moff;
                  /*
                   * If mp is set, just pass back the mbufs.  Otherwise copy
                   * them out via the uio, then free.  Sockbuf must be
                   * consistent here (points to current mbuf, it points to next
                   * record) when we drop priority; we must note any additions
                   * to the sockbuf when we block interrupts again.
                   */
                  if (mp == NULL) {
                          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                          SBLASTRECORDCHK(&so->so_rcv);
                          SBLASTMBUFCHK(&so->so_rcv);
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          if ((m->m_flags & M_EXTPG) != 0)
                                  error = m_unmapped_uiomove(m, moff, uio,
                                      (int)len);
                          else
                                  error = uiomove(mtod(m, char *) + moff,
                                      (int)len, uio);
                          SOCKBUF_LOCK(&so->so_rcv);
                          if (error) {
                                  /*
                                   * The MT_SONAME mbuf has already been removed
                                   * from the record, so it is necessary to
                                   * remove the data mbufs, if any, to preserve
                                   * the invariant in the case of PR_ADDR that
                                   * requires MT_SONAME mbufs at the head of
                                   * each record.
                                   */
                                  if (pr->pr_flags & PR_ATOMIC &&
                                      ((flags & MSG_PEEK) == 0))
                                          (void)sbdroprecord_locked(&so->so_rcv);
                                  SOCKBUF_UNLOCK(&so->so_rcv);
                                  goto release;
                          }
                  } else
                          uio->uio_resid -= len;
                  SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                  if (len == m->m_len - moff) {
                          if (m->m_flags & M_EOR)
                                  flags |= MSG_EOR;
                          if (flags & MSG_PEEK) {
                                  m = m->m_next;
                                  moff = 0;
                          } else {
                                  nextrecord = m->m_nextpkt;
                                  sbfree(&so->so_rcv, m);
                                  if (mp != NULL) {
                                          m->m_nextpkt = NULL;
                                          *mp = m;
                                          mp = &m->m_next;
                                          so->so_rcv.sb_mb = m = m->m_next;
                                          *mp = NULL;
                                  } else {
                                          so->so_rcv.sb_mb = m_free(m);
                                          m = so->so_rcv.sb_mb;
                                  }
                                  sockbuf_pushsync(&so->so_rcv, nextrecord);
                                  SBLASTRECORDCHK(&so->so_rcv);
                                  SBLASTMBUFCHK(&so->so_rcv);
                          }
                  } else {
                          if (flags & MSG_PEEK)
                                  moff += len;
                          else {
                                  if (mp != NULL) {
                                          if (flags & MSG_DONTWAIT) {
                                                  *mp = m_copym(m, 0, len,
                                                      M_NOWAIT);
                                                  if (*mp == NULL) {
                                                          /*
                                                           * m_copym() couldn't
                                                           * allocate an mbuf.
                                                           * Adjust uio_resid back
                                                           * (it was adjusted
                                                           * down by len bytes,
                                                           * which we didn't end
                                                           * up "copying" over).
                                                           */
                                                          uio->uio_resid += len;
                                                          break;
                                                  }
                                          } else {
                                                  SOCKBUF_UNLOCK(&so->so_rcv);
                                                  *mp = m_copym(m, 0, len,
                                                      M_WAITOK);
                                                  SOCKBUF_LOCK(&so->so_rcv);
                                          }
                                  }
                                  sbcut_locked(&so->so_rcv, len);
                          }
                  }
                  SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                  if (so->so_oobmark) {
                          if ((flags & MSG_PEEK) == 0) {
                                  so->so_oobmark -= len;
                                  if (so->so_oobmark == 0) {
                                          so->so_rcv.sb_state |= SBS_RCVATMARK;
                                          break;
                                  }
                          } else {
                                  offset += len;
                                  if (offset == so->so_oobmark)
                                          break;
                          }
                  }
                  if (flags & MSG_EOR)
                          break;
                  /*
                   * If the MSG_WAITALL flag is set (for non-atomic socket), we
                   * must not quit until "uio->uio_resid == 0" or an error
                   * termination.  If a signal/timeout occurs, return with a
                   * short count but without error.  Keep sockbuf locked
                   * against other readers.
                   */
                  while (flags & MSG_WAITALL && m == NULL && uio->uio_resid > 0 &&
                      !sosendallatonce(so) && nextrecord == NULL) {
                          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
                          if (so->so_error || so->so_rerror ||
                              so->so_rcv.sb_state & SBS_CANTRCVMORE)
                                  break;
                          /*
                           * Notify the protocol that some data has been
                           * drained before blocking.
                           */
                          if (pr->pr_flags & PR_WANTRCVD) {
                                  SOCKBUF_UNLOCK(&so->so_rcv);
                                  VNET_SO_ASSERT(so);
                                  pr->pr_rcvd(so, flags);
                                  SOCKBUF_LOCK(&so->so_rcv);
                          }
                          SBLASTRECORDCHK(&so->so_rcv);
                          SBLASTMBUFCHK(&so->so_rcv);
                          /*
                           * We could receive some data while was notifying
                           * the protocol. Skip blocking in this case.
                           */
                          if (so->so_rcv.sb_mb == NULL) {
                                  error = sbwait(so, SO_RCV);
                                  if (error) {
                                          SOCKBUF_UNLOCK(&so->so_rcv);
                                          goto release;
                                  }
                          }
                          m = so->so_rcv.sb_mb;
                          if (m != NULL)
                                  nextrecord = m->m_nextpkt;
                  }
          }
  
          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
          if (m != NULL && pr->pr_flags & PR_ATOMIC) {
                  if (report_real_len)
                          uio->uio_resid -= m_length(m, NULL) - moff;
                  flags |= MSG_TRUNC;
                  if ((flags & MSG_PEEK) == 0)
                          (void) sbdroprecord_locked(&so->so_rcv);
          }
          if ((flags & MSG_PEEK) == 0) {
                  if (m == NULL) {
                          /*
                           * First part is an inline SB_EMPTY_FIXUP().  Second
                           * part makes sure sb_lastrecord is up-to-date if
                           * there is still data in the socket buffer.
                           */
                          so->so_rcv.sb_mb = nextrecord;
                          if (so->so_rcv.sb_mb == NULL) {
                                  so->so_rcv.sb_mbtail = NULL;
                                  so->so_rcv.sb_lastrecord = NULL;
                          } else if (nextrecord->m_nextpkt == NULL)
                                  so->so_rcv.sb_lastrecord = nextrecord;
                  }
                  SBLASTRECORDCHK(&so->so_rcv);
                  SBLASTMBUFCHK(&so->so_rcv);
                  /*
                   * If soreceive() is being done from the socket callback,
                   * then don't need to generate ACK to peer to update window,
                   * since ACK will be generated on return to TCP.
                   */
                  if (!(flags & MSG_SOCALLBCK) &&
                      (pr->pr_flags & PR_WANTRCVD)) {
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          VNET_SO_ASSERT(so);
                          pr->pr_rcvd(so, flags);
                          SOCKBUF_LOCK(&so->so_rcv);
                  }
          }
          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
          if (orig_resid == uio->uio_resid && orig_resid &&
              (flags & MSG_EOR) == 0 && (so->so_rcv.sb_state & SBS_CANTRCVMORE) == 0) {
                  SOCKBUF_UNLOCK(&so->so_rcv);
                  goto restart;
          }
          SOCKBUF_UNLOCK(&so->so_rcv);
  
          if (flagsp != NULL)
                  *flagsp |= flags;
  release:
          SOCK_IO_RECV_UNLOCK(so);
          return (error);
  }
  
  /*
   * Optimized version of soreceive() for stream (TCP) sockets.
   */
  int
  soreceive_stream(struct socket *so, struct sockaddr **psa, struct uio *uio,
      struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
  {
          int len = 0, error = 0, flags, oresid;
          struct sockbuf *sb;
          struct mbuf *m, *n = NULL;
  
          /* We only do stream sockets. */
          if (so->so_type != SOCK_STREAM)
                  return (EINVAL);
          if (psa != NULL)
                  *psa = NULL;
          if (flagsp != NULL)
                  flags = *flagsp &~ MSG_EOR;
          else
                  flags = 0;
          if (controlp != NULL)
                  *controlp = NULL;
          if (flags & MSG_OOB)
                  return (soreceive_rcvoob(so, uio, flags));
          if (mp0 != NULL)
                  *mp0 = NULL;
  
          sb = &so->so_rcv;
  
  #ifdef KERN_TLS
          /*
           * KTLS store TLS records as records with a control message to
           * describe the framing.
           *
           * We check once here before acquiring locks to optimize the
           * common case.
           */
          if (sb->sb_tls_info != NULL)
                  return (soreceive_generic(so, psa, uio, mp0, controlp,
                      flagsp));
  #endif
  
          /* Prevent other readers from entering the socket. */
          error = SOCK_IO_RECV_LOCK(so, SBLOCKWAIT(flags));
          if (error)
                  return (error);
          SOCKBUF_LOCK(sb);
  
  #ifdef KERN_TLS
          if (sb->sb_tls_info != NULL) {
                  SOCKBUF_UNLOCK(sb);
                  SOCK_IO_RECV_UNLOCK(so);
                  return (soreceive_generic(so, psa, uio, mp0, controlp,
                      flagsp));
          }
  #endif
  
          /* Easy one, no space to copyout anything. */
          if (uio->uio_resid == 0) {
                  error = EINVAL;
                  goto out;
          }
          oresid = uio->uio_resid;
  
          /* We will never ever get anything unless we are or were connected. */
          if (!(so->so_state & (SS_ISCONNECTED|SS_ISDISCONNECTED))) {
                  error = ENOTCONN;
                  goto out;
          }
  
  restart:
          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
  
          /* Abort if socket has reported problems. */
          if (so->so_error) {
                  if (sbavail(sb) > 0)
                          goto deliver;
                  if (oresid > uio->uio_resid)
                          goto out;
                  error = so->so_error;
                  if (!(flags & MSG_PEEK))
                          so->so_error = 0;
                  goto out;
          }
  
          /* Door is closed.  Deliver what is left, if any. */
          if (sb->sb_state & SBS_CANTRCVMORE) {
                  if (sbavail(sb) > 0)
                          goto deliver;
                  else
                          goto out;
          }
  
          /* Socket buffer is empty and we shall not block. */
          if (sbavail(sb) == 0 &&
              ((so->so_state & SS_NBIO) || (flags & (MSG_DONTWAIT|MSG_NBIO)))) {
                  error = EAGAIN;
                  goto out;
          }
  
          /* Socket buffer got some data that we shall deliver now. */
          if (sbavail(sb) > 0 && !(flags & MSG_WAITALL) &&
              ((so->so_state & SS_NBIO) ||
               (flags & (MSG_DONTWAIT|MSG_NBIO)) ||
               sbavail(sb) >= sb->sb_lowat ||
               sbavail(sb) >= uio->uio_resid ||
               sbavail(sb) >= sb->sb_hiwat) ) {
                  goto deliver;
          }
  
          /* On MSG_WAITALL we must wait until all data or error arrives. */
          if ((flags & MSG_WAITALL) &&
              (sbavail(sb) >= uio->uio_resid || sbavail(sb) >= sb->sb_hiwat))
                  goto deliver;
  
          /*
           * Wait and block until (more) data comes in.
           * NB: Drops the sockbuf lock during wait.
           */
          error = sbwait(so, SO_RCV);
          if (error)
                  goto out;
          goto restart;
  
  deliver:
          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
          KASSERT(sbavail(sb) > 0, ("%s: sockbuf empty", __func__));
          KASSERT(sb->sb_mb != NULL, ("%s: sb_mb == NULL", __func__));
  
          /* Statistics. */
          if (uio->uio_td)
                  uio->uio_td->td_ru.ru_msgrcv++;
  
          /* Fill uio until full or current end of socket buffer is reached. */
          len = min(uio->uio_resid, sbavail(sb));
          if (mp0 != NULL) {
                  /* Dequeue as many mbufs as possible. */
                  if (!(flags & MSG_PEEK) && len >= sb->sb_mb->m_len) {
                          if (*mp0 == NULL)
                                  *mp0 = sb->sb_mb;
                          else
                                  m_cat(*mp0, sb->sb_mb);
                          for (m = sb->sb_mb;
                               m != NULL && m->m_len <= len;
                               m = m->m_next) {
                                  KASSERT(!(m->m_flags & M_NOTAVAIL),
                                      ("%s: m %p not available", __func__, m));
                                  len -= m->m_len;
                                  uio->uio_resid -= m->m_len;
                                  sbfree(sb, m);
                                  n = m;
                          }
                          n->m_next = NULL;
                          sb->sb_mb = m;
                          sb->sb_lastrecord = sb->sb_mb;
                          if (sb->sb_mb == NULL)
                                  SB_EMPTY_FIXUP(sb);
                  }
                  /* Copy the remainder. */
                  if (len > 0) {
                          KASSERT(sb->sb_mb != NULL,
                              ("%s: len > 0 && sb->sb_mb empty", __func__));
  
                          m = m_copym(sb->sb_mb, 0, len, M_NOWAIT);
                          if (m == NULL)
                                  len = 0;        /* Don't flush data from sockbuf. */
                          else
                                  uio->uio_resid -= len;
                          if (*mp0 != NULL)
                                  m_cat(*mp0, m);
                          else
                                  *mp0 = m;
                          if (*mp0 == NULL) {
                                  error = ENOBUFS;
                                  goto out;
                          }
                  }
          } else {
                  /* NB: Must unlock socket buffer as uiomove may sleep. */
                  SOCKBUF_UNLOCK(sb);
                  error = m_mbuftouio(uio, sb->sb_mb, len);
                  SOCKBUF_LOCK(sb);
                  if (error)
                          goto out;
          }
          SBLASTRECORDCHK(sb);
          SBLASTMBUFCHK(sb);
  
          /*
           * Remove the delivered data from the socket buffer unless we
           * were only peeking.
           */
          if (!(flags & MSG_PEEK)) {
                  if (len > 0)
                          sbdrop_locked(sb, len);
  
                  /* Notify protocol that we drained some data. */
                  if ((so->so_proto->pr_flags & PR_WANTRCVD) &&
                      (((flags & MSG_WAITALL) && uio->uio_resid > 0) ||
                       !(flags & MSG_SOCALLBCK))) {
                          SOCKBUF_UNLOCK(sb);
                          VNET_SO_ASSERT(so);
                          so->so_proto->pr_rcvd(so, flags);
                          SOCKBUF_LOCK(sb);
                  }
          }
  
          /*
           * For MSG_WAITALL we may have to loop again and wait for
           * more data to come in.
           */
          if ((flags & MSG_WAITALL) && uio->uio_resid > 0)
                  goto restart;
  out:
          SBLASTRECORDCHK(sb);
          SBLASTMBUFCHK(sb);
          SOCKBUF_UNLOCK(sb);
          SOCK_IO_RECV_UNLOCK(so);
          return (error);
  }
  
  /*
   * Optimized version of soreceive() for simple datagram cases from userspace.
   * Unlike in the stream case, we're able to drop a datagram if copyout()
   * fails, and because we handle datagrams atomically, we don't need to use a
   * sleep lock to prevent I/O interlacing.
   */
  int
  soreceive_dgram(struct socket *so, struct sockaddr **psa, struct uio *uio,
      struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
  {
          struct mbuf *m, *m2;
          int flags, error;
          ssize_t len;
          struct protosw *pr = so->so_proto;
          struct mbuf *nextrecord;
  
          if (psa != NULL)
                  *psa = NULL;
          if (controlp != NULL)
                  *controlp = NULL;
          if (flagsp != NULL)
                  flags = *flagsp &~ MSG_EOR;
          else
                  flags = 0;
  
          /*
           * For any complicated cases, fall back to the full
           * soreceive_generic().
           */
          if (mp0 != NULL || (flags & (MSG_PEEK | MSG_OOB | MSG_TRUNC)))
                  return (soreceive_generic(so, psa, uio, mp0, controlp,
                      flagsp));
  
          /*
           * Enforce restrictions on use.
           */
          KASSERT((pr->pr_flags & PR_WANTRCVD) == 0,
              ("soreceive_dgram: wantrcvd"));
          KASSERT(pr->pr_flags & PR_ATOMIC, ("soreceive_dgram: !atomic"));
          KASSERT((so->so_rcv.sb_state & SBS_RCVATMARK) == 0,
              ("soreceive_dgram: SBS_RCVATMARK"));
          KASSERT((so->so_proto->pr_flags & PR_CONNREQUIRED) == 0,
              ("soreceive_dgram: P_CONNREQUIRED"));
  
          /*
           * Loop blocking while waiting for a datagram.
           */
          SOCKBUF_LOCK(&so->so_rcv);
          while ((m = so->so_rcv.sb_mb) == NULL) {
                  KASSERT(sbavail(&so->so_rcv) == 0,
                      ("soreceive_dgram: sb_mb NULL but sbavail %u",
                      sbavail(&so->so_rcv)));
                  if (so->so_error) {
                          error = so->so_error;
                          so->so_error = 0;
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          return (error);
                  }
                  if (so->so_rcv.sb_state & SBS_CANTRCVMORE ||
                      uio->uio_resid == 0) {
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          return (0);
                  }
                  if ((so->so_state & SS_NBIO) ||
                      (flags & (MSG_DONTWAIT|MSG_NBIO))) {
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          return (EWOULDBLOCK);
                  }
                  SBLASTRECORDCHK(&so->so_rcv);
                  SBLASTMBUFCHK(&so->so_rcv);
                  error = sbwait(so, SO_RCV);
                  if (error) {
                          SOCKBUF_UNLOCK(&so->so_rcv);
                          return (error);
                  }
          }
          SOCKBUF_LOCK_ASSERT(&so->so_rcv);
  
          if (uio->uio_td)
                  uio->uio_td->td_ru.ru_msgrcv++;
          SBLASTRECORDCHK(&so->so_rcv);
          SBLASTMBUFCHK(&so->so_rcv);
          nextrecord = m->m_nextpkt;
          if (nextrecord == NULL) {
                  KASSERT(so->so_rcv.sb_lastrecord == m,
                      ("soreceive_dgram: lastrecord != m"));
          }
  
          KASSERT(so->so_rcv.sb_mb->m_nextpkt == nextrecord,
              ("soreceive_dgram: m_nextpkt != nextrecord"));
  
          /*
           * Pull 'm' and its chain off the front of the packet queue.
           */
          so->so_rcv.sb_mb = NULL;
          sockbuf_pushsync(&so->so_rcv, nextrecord);
  
          /*
           * Walk 'm's chain and free that many bytes from the socket buffer.
           */
          for (m2 = m; m2 != NULL; m2 = m2->m_next)
                  sbfree(&so->so_rcv, m2);
  
          /*
           * Do a few last checks before we let go of the lock.
           */
          SBLASTRECORDCHK(&so->so_rcv);
          SBLASTMBUFCHK(&so->so_rcv);
          SOCKBUF_UNLOCK(&so->so_rcv);
  
          if (pr->pr_flags & PR_ADDR) {
                  KASSERT(m->m_type == MT_SONAME,
                      ("m->m_type == %d", m->m_type));
                  if (psa != NULL)
                          *psa = sodupsockaddr(mtod(m, struct sockaddr *),
                              M_NOWAIT);
                  m = m_free(m);
          }
          if (m == NULL) {
                  /* XXXRW: Can this happen? */
                  return (0);
          }
  
          /*
           * Packet to copyout() is now in 'm' and it is disconnected from the
           * queue.
           *
           * Process one or more MT_CONTROL mbufs present before any data mbufs
           * in the first mbuf chain on the socket buffer.  We call into the
           * protocol to perform externalization (or freeing if controlp ==
           * NULL). In some cases there can be only MT_CONTROL mbufs without
           * MT_DATA mbufs.
           */
          if (m->m_type == MT_CONTROL) {
                  struct mbuf *cm = NULL, *cmn;
                  struct mbuf **cme = &cm;
  
                  do {
                          m2 = m->m_next;
                          m->m_next = NULL;
                          *cme = m;
                          cme = &(*cme)->m_next;
                          m = m2;
                  } while (m != NULL && m->m_type == MT_CONTROL);
                  while (cm != NULL) {
                          cmn = cm->m_next;
                          cm->m_next = NULL;
                          if (pr->pr_domain->dom_externalize != NULL) {
                                  error = (*pr->pr_domain->dom_externalize)
                                      (cm, controlp, flags);
                          } else if (controlp != NULL)
                                  *controlp = cm;
                          else
                                  m_freem(cm);
                          if (controlp != NULL) {
                                  while (*controlp != NULL)
                                          controlp = &(*controlp)->m_next;
                          }
                          cm = cmn;
                  }
          }
          KASSERT(m == NULL || m->m_type == MT_DATA,
              ("soreceive_dgram: !data"));
          while (m != NULL && uio->uio_resid > 0) {
                  len = uio->uio_resid;
                  if (len > m->m_len)
                          len = m->m_len;
                  error = uiomove(mtod(m, char *), (int)len, uio);
                  if (error) {
                          m_freem(m);
                          return (error);
                  }
                  if (len == m->m_len)
                          m = m_free(m);
                  else {
                          m->m_data += len;
                          m->m_len -= len;
                  }
          }
          if (m != NULL) {
                  flags |= MSG_TRUNC;
                  m_freem(m);
          }
          if (flagsp != NULL)
                  *flagsp |= flags;
          return (0);
  }
  
  int
  soreceive(struct socket *so, struct sockaddr **psa, struct uio *uio,
      struct mbuf **mp0, struct mbuf **controlp, int *flagsp)
  {
          int error;
  
          CURVNET_SET(so->so_vnet);
          error = so->so_proto->pr_soreceive(so, psa, uio, mp0, controlp, flagsp);
          CURVNET_RESTORE();
          return (error);
  }
  
  int
  soshutdown(struct socket *so, int how)
  {
          struct protosw *pr;
          int error, soerror_enotconn;
  
          if (!(how == SHUT_RD || how == SHUT_WR || how == SHUT_RDWR))
                  return (EINVAL);
  
          soerror_enotconn = 0;
          SOCK_LOCK(so);
          if ((so->so_state &
              (SS_ISCONNECTED | SS_ISCONNECTING | SS_ISDISCONNECTING)) == 0) {
                  /*
                   * POSIX mandates us to return ENOTCONN when shutdown(2) is
                   * invoked on a datagram sockets, however historically we would
                   * actually tear socket down. This is known to be leveraged by
                   * some applications to unblock process waiting in recvXXX(2)
                   * by other process that it shares that socket with. Try to meet
                   * both backward-compatibility and POSIX requirements by forcing
                   * ENOTCONN but still asking protocol to perform pru_shutdown().
                   */
                  if (so->so_type != SOCK_DGRAM && !SOLISTENING(so)) {
                          SOCK_UNLOCK(so);
                          return (ENOTCONN);
                  }
                  soerror_enotconn = 1;
          }
  
          if (SOLISTENING(so)) {
                  if (how != SHUT_WR) {
                          so->so_error = ECONNABORTED;
                          solisten_wakeup(so);    /* unlocks so */
                  } else {
                          SOCK_UNLOCK(so);
                  }
                  goto done;
          }
          SOCK_UNLOCK(so);
  
          CURVNET_SET(so->so_vnet);
          pr = so->so_proto;
          if (pr->pr_flush != NULL)
                  pr->pr_flush(so, how);
          if (how != SHUT_WR)
                  sorflush(so);
          if (how != SHUT_RD) {
                  error = pr->pr_shutdown(so);
                  wakeup(&so->so_timeo);
                  CURVNET_RESTORE();
                  return ((error == 0 && soerror_enotconn) ? ENOTCONN : error);
          }
          wakeup(&so->so_timeo);
          CURVNET_RESTORE();
  
  done:
          return (soerror_enotconn ? ENOTCONN : 0);
  }
  
  void
  sorflush(struct socket *so)
  {
          struct protosw *pr;
          int error;
  
          VNET_SO_ASSERT(so);
  
          /*
           * Dislodge threads currently blocked in receive and wait to acquire
           * a lock against other simultaneous readers before clearing the
           * socket buffer.  Don't let our acquire be interrupted by a signal
           * despite any existing socket disposition on interruptable waiting.
           */
          socantrcvmore(so);
  
          error = SOCK_IO_RECV_LOCK(so, SBL_WAIT | SBL_NOINTR);
          if (error != 0) {
                  KASSERT(SOLISTENING(so),
                      ("%s: soiolock(%p) failed", __func__, so));
                  return;
          }
  
          pr = so->so_proto;
          if (pr->pr_flags & PR_RIGHTS) {
                  MPASS(pr->pr_domain->dom_dispose != NULL);
                  (*pr->pr_domain->dom_dispose)(so);
          } else {
                  sbrelease(so, SO_RCV);
                  SOCK_IO_RECV_UNLOCK(so);
          }
  
  }
  
  /*
   * Wrapper for Socket established helper hook.
   * Parameters: socket, context of the hook point, hook id.
   */
  static int inline
  hhook_run_socket(struct socket *so, void *hctx, int32_t h_id)
  {
          struct socket_hhook_data hhook_data = {
                  .so = so,
                  .hctx = hctx,
                  .m = NULL,
                  .status = 0
          };
  
          CURVNET_SET(so->so_vnet);
          HHOOKS_RUN_IF(V_socket_hhh[h_id], &hhook_data, &so->osd);
          CURVNET_RESTORE();
  
          /* Ugly but needed, since hhooks return void for now */
          return (hhook_data.status);
  }
  
  /*
   * Perhaps this routine, and sooptcopyout(), below, ought to come in an
   * additional variant to handle the case where the option value needs to be
   * some kind of integer, but not a specific size.  In addition to their use
   * here, these functions are also called by the protocol-level pr_ctloutput()
   * routines.
   */
  int
  sooptcopyin(struct sockopt *sopt, void *buf, size_t len, size_t minlen)
  {
          size_t  valsize;
  
          /*
           * If the user gives us more than we wanted, we ignore it, but if we
           * don't get the minimum length the caller wants, we return EINVAL.
           * On success, sopt->sopt_valsize is set to however much we actually
           * retrieved.
           */
          if ((valsize = sopt->sopt_valsize) < minlen)
                  return EINVAL;
          if (valsize > len)
                  sopt->sopt_valsize = valsize = len;
  
          if (sopt->sopt_td != NULL)
                  return (copyin(sopt->sopt_val, buf, valsize));
  
          bcopy(sopt->sopt_val, buf, valsize);
          return (0);
  }
  
  /*
   * Kernel version of setsockopt(2).
   *
   * XXX: optlen is size_t, not socklen_t
   */
  int
  so_setsockopt(struct socket *so, int level, int optname, void *optval,
      size_t optlen)
  {
          struct sockopt sopt;
  
          sopt.sopt_level = level;
          sopt.sopt_name = optname;
          sopt.sopt_dir = SOPT_SET;
          sopt.sopt_val = optval;
          sopt.sopt_valsize = optlen;
          sopt.sopt_td = NULL;
          return (sosetopt(so, &sopt));
  }
  
  int
  sosetopt(struct socket *so, struct sockopt *sopt)
  {
          int     error, optval;
          struct  linger l;
          struct  timeval tv;
          sbintime_t val, *valp;
          uint32_t val32;
  #ifdef MAC
          struct mac extmac;
  #endif
  
          CURVNET_SET(so->so_vnet);
          error = 0;
          if (sopt->sopt_level != SOL_SOCKET) {
                  if (so->so_proto->pr_ctloutput != NULL)
                          error = (*so->so_proto->pr_ctloutput)(so, sopt);
                  else
                          error = ENOPROTOOPT;
          } else {
                  switch (sopt->sopt_name) {
                  case SO_ACCEPTFILTER:
                          error = accept_filt_setopt(so, sopt);
                          if (error)
                                  goto bad;
                          break;
  
                  case SO_LINGER:
                          error = sooptcopyin(sopt, &l, sizeof l, sizeof l);
                          if (error)
                                  goto bad;
                          if (l.l_linger < 0 ||
                              l.l_linger > USHRT_MAX ||
                              l.l_linger > (INT_MAX / hz)) {
                                  error = EDOM;
                                  goto bad;
                          }
                          SOCK_LOCK(so);
                          so->so_linger = l.l_linger;
                          if (l.l_onoff)
                                  so->so_options |= SO_LINGER;
                          else
                                  so->so_options &= ~SO_LINGER;
                          SOCK_UNLOCK(so);
                          break;
  
                  case SO_DEBUG:
                  case SO_KEEPALIVE:
                  case SO_DONTROUTE:
                  case SO_USELOOPBACK:
                  case SO_BROADCAST:
                  case SO_REUSEADDR:
                  case SO_REUSEPORT:
                  case SO_REUSEPORT_LB:
                  case SO_OOBINLINE:
                  case SO_TIMESTAMP:
                  case SO_BINTIME:
                  case SO_NOSIGPIPE:
                  case SO_NO_DDP:
                  case SO_NO_OFFLOAD:
                  case SO_RERROR:
                          error = sooptcopyin(sopt, &optval, sizeof optval,
                              sizeof optval);
                          if (error)
                                  goto bad;
                          SOCK_LOCK(so);
                          if (optval)
                                  so->so_options |= sopt->sopt_name;
                          else
                                  so->so_options &= ~sopt->sopt_name;
                          SOCK_UNLOCK(so);
                          break;
  
                  case SO_SETFIB:
                          error = sooptcopyin(sopt, &optval, sizeof optval,
                              sizeof optval);
                          if (error)
                                  goto bad;
  
                          if (optval < 0 || optval >= rt_numfibs) {
                                  error = EINVAL;
                                  goto bad;
                          }
                          if (((so->so_proto->pr_domain->dom_family == PF_INET) ||
                             (so->so_proto->pr_domain->dom_family == PF_INET6) ||
                             (so->so_proto->pr_domain->dom_family == PF_ROUTE)))
                                  so->so_fibnum = optval;
                          else
                                  so->so_fibnum = 0;
                          break;
  
                  case SO_USER_COOKIE:
                          error = sooptcopyin(sopt, &val32, sizeof val32,
                              sizeof val32);
                          if (error)
                                  goto bad;
                          so->so_user_cookie = val32;
                          break;
  
                  case SO_SNDBUF:
                  case SO_RCVBUF:
                  case SO_SNDLOWAT:
                  case SO_RCVLOWAT:
                          error = so->so_proto->pr_setsbopt(so, sopt);
                          if (error)
                                  goto bad;
                          break;
  
                  case SO_SNDTIMEO:
                  case SO_RCVTIMEO:
  #ifdef COMPAT_FREEBSD32
                          if (SV_CURPROC_FLAG(SV_ILP32)) {
                                  struct timeval32 tv32;
  
                                  error = sooptcopyin(sopt, &tv32, sizeof tv32,
                                      sizeof tv32);
                                  CP(tv32, tv, tv_sec);
                                  CP(tv32, tv, tv_usec);
                          } else
  #endif
                                  error = sooptcopyin(sopt, &tv, sizeof tv,
                                      sizeof tv);
                          if (error)
                                  goto bad;
                          if (tv.tv_sec < 0 || tv.tv_usec < 0 ||
                              tv.tv_usec >= 1000000) {
                                  error = EDOM;
                                  goto bad;
                          }
                          if (tv.tv_sec > INT32_MAX)
                                  val = SBT_MAX;
                          else
                                  val = tvtosbt(tv);
                          SOCK_LOCK(so);
                          valp = sopt->sopt_name == SO_SNDTIMEO ?
                              (SOLISTENING(so) ? &so->sol_sbsnd_timeo :
                              &so->so_snd.sb_timeo) :
                              (SOLISTENING(so) ? &so->sol_sbrcv_timeo :
                              &so->so_rcv.sb_timeo);
                          *valp = val;
                          SOCK_UNLOCK(so);
                          break;
  
                  case SO_LABEL:
  #ifdef MAC
                          error = sooptcopyin(sopt, &extmac, sizeof extmac,
                              sizeof extmac);
                          if (error)
                                  goto bad;
                          error = mac_setsockopt_label(sopt->sopt_td->td_ucred,
                              so, &extmac);
  #else
                          error = EOPNOTSUPP;
  #endif
                          break;
  
                  case SO_TS_CLOCK:
                          error = sooptcopyin(sopt, &optval, sizeof optval,
                              sizeof optval);
                          if (error)
                                  goto bad;
                          if (optval < 0 || optval > SO_TS_CLOCK_MAX) {
                                  error = EINVAL;
                                  goto bad;
                          }
                          so->so_ts_clock = optval;
                          break;
  
                  case SO_MAX_PACING_RATE:
                          error = sooptcopyin(sopt, &val32, sizeof(val32),
                              sizeof(val32));
                          if (error)
                                  goto bad;
                          so->so_max_pacing_rate = val32;
                          break;
  
                  default:
                          if (V_socket_hhh[HHOOK_SOCKET_OPT]->hhh_nhooks > 0)
                                  error = hhook_run_socket(so, sopt,
                                      HHOOK_SOCKET_OPT);
                          else
                                  error = ENOPROTOOPT;
                          break;
                  }
                  if (error == 0 && so->so_proto->pr_ctloutput != NULL)
                          (void)(*so->so_proto->pr_ctloutput)(so, sopt);
          }
  bad:
          CURVNET_RESTORE();
          return (error);
  }
  
  /*
   * Helper routine for getsockopt.
   */
  int
  sooptcopyout(struct sockopt *sopt, const void *buf, size_t len)
  {
          int     error;
          size_t  valsize;
  
          error = 0;
  
          /*
           * Documented get behavior is that we always return a value, possibly
           * truncated to fit in the user's buffer.  Traditional behavior is
           * that we always tell the user precisely how much we copied, rather
           * than something useful like the total amount we had available for
           * her.  Note that this interface is not idempotent; the entire
           * answer must be generated ahead of time.
           */
          valsize = min(len, sopt->sopt_valsize);
          sopt->sopt_valsize = valsize;
          if (sopt->sopt_val != NULL) {
                  if (sopt->sopt_td != NULL)
                          error = copyout(buf, sopt->sopt_val, valsize);
                  else
                          bcopy(buf, sopt->sopt_val, valsize);
          }
          return (error);
  }
  
  int
  sogetopt(struct socket *so, struct sockopt *sopt)
  {
          int     error, optval;
          struct  linger l;
          struct  timeval tv;
  #ifdef MAC
          struct mac extmac;
  #endif
  
          CURVNET_SET(so->so_vnet);
          error = 0;
          if (sopt->sopt_level != SOL_SOCKET) {
                  if (so->so_proto->pr_ctloutput != NULL)
                          error = (*so->so_proto->pr_ctloutput)(so, sopt);
                  else
                          error = ENOPROTOOPT;
                  CURVNET_RESTORE();
                  return (error);
          } else {
                  switch (sopt->sopt_name) {
                  case SO_ACCEPTFILTER:
                          error = accept_filt_getopt(so, sopt);
                          break;
  
                  case SO_LINGER:
                          SOCK_LOCK(so);
                          l.l_onoff = so->so_options & SO_LINGER;
                          l.l_linger = so->so_linger;
                          SOCK_UNLOCK(so);
                          error = sooptcopyout(sopt, &l, sizeof l);
                          break;
  
                  case SO_USELOOPBACK:
                  case SO_DONTROUTE:
                  case SO_DEBUG:
                  case SO_KEEPALIVE:
                  case SO_REUSEADDR:
                  case SO_REUSEPORT:
                  case SO_REUSEPORT_LB:
                  case SO_BROADCAST:
                  case SO_OOBINLINE:
                  case SO_ACCEPTCONN:
                  case SO_TIMESTAMP:
                  case SO_BINTIME:
                  case SO_NOSIGPIPE:
                  case SO_NO_DDP:
                  case SO_NO_OFFLOAD:
                  case SO_RERROR:
                          optval = so->so_options & sopt->sopt_name;
  integer:
                          error = sooptcopyout(sopt, &optval, sizeof optval);
                          break;
  
                  case SO_DOMAIN:
                          optval = so->so_proto->pr_domain->dom_family;
                          goto integer;
  
                  case SO_TYPE:
                          optval = so->so_type;
                          goto integer;
  
                  case SO_PROTOCOL:
                          optval = so->so_proto->pr_protocol;
                          goto integer;
  
                  case SO_ERROR:
                          SOCK_LOCK(so);
                          if (so->so_error) {
                                  optval = so->so_error;
                                  so->so_error = 0;
                          } else {
                                  optval = so->so_rerror;
                                  so->so_rerror = 0;
                          }
                          SOCK_UNLOCK(so);
                          goto integer;
  
                  case SO_SNDBUF:
                          optval = SOLISTENING(so) ? so->sol_sbsnd_hiwat :
                              so->so_snd.sb_hiwat;
                          goto integer;
  
                  case SO_RCVBUF:
                          optval = SOLISTENING(so) ? so->sol_sbrcv_hiwat :
                              so->so_rcv.sb_hiwat;
                          goto integer;
  
                  case SO_SNDLOWAT:
                          optval = SOLISTENING(so) ? so->sol_sbsnd_lowat :
                              so->so_snd.sb_lowat;
                          goto integer;
  
                  case SO_RCVLOWAT:
                          optval = SOLISTENING(so) ? so->sol_sbrcv_lowat :
                              so->so_rcv.sb_lowat;
                          goto integer;
  
                  case SO_SNDTIMEO:
                  case SO_RCVTIMEO:
                          SOCK_LOCK(so);
                          tv = sbttotv(sopt->sopt_name == SO_SNDTIMEO ?
                              (SOLISTENING(so) ? so->sol_sbsnd_timeo :
                              so->so_snd.sb_timeo) :
                              (SOLISTENING(so) ? so->sol_sbrcv_timeo :
                              so->so_rcv.sb_timeo));
                          SOCK_UNLOCK(so);
  #ifdef COMPAT_FREEBSD32
                          if (SV_CURPROC_FLAG(SV_ILP32)) {
                                  struct timeval32 tv32;
  
                                  CP(tv, tv32, tv_sec);
                                  CP(tv, tv32, tv_usec);
                                  error = sooptcopyout(sopt, &tv32, sizeof tv32);
                          } else
  #endif
                                  error = sooptcopyout(sopt, &tv, sizeof tv);
                          break;
  
                  case SO_LABEL:
  #ifdef MAC
                          error = sooptcopyin(sopt, &extmac, sizeof(extmac),
                              sizeof(extmac));
                          if (error)
                                  goto bad;
                          error = mac_getsockopt_label(sopt->sopt_td->td_ucred,
                              so, &extmac);
                          if (error)
                                  goto bad;
                          error = sooptcopyout(sopt, &extmac, sizeof extmac);
  #else
                          error = EOPNOTSUPP;
  #endif
                          break;
  
                  case SO_PEERLABEL:
  #ifdef MAC
                          error = sooptcopyin(sopt, &extmac, sizeof(extmac),
                              sizeof(extmac));
                          if (error)
                                  goto bad;
                          error = mac_getsockopt_peerlabel(
                              sopt->sopt_td->td_ucred, so, &extmac);
                          if (error)
                                  goto bad;
                          error = sooptcopyout(sopt, &extmac, sizeof extmac);
  #else
                          error = EOPNOTSUPP;
  #endif
                          break;
  
                  case SO_LISTENQLIMIT:
                          optval = SOLISTENING(so) ? so->sol_qlimit : 0;
                          goto integer;
  
                  case SO_LISTENQLEN:
                          optval = SOLISTENING(so) ? so->sol_qlen : 0;
                          goto integer;
  
                  case SO_LISTENINCQLEN:
                          optval = SOLISTENING(so) ? so->sol_incqlen : 0;
                          goto integer;
  
                  case SO_TS_CLOCK:
                          optval = so->so_ts_clock;
                          goto integer;
  
                  case SO_MAX_PACING_RATE:
                          optval = so->so_max_pacing_rate;
                          goto integer;
  
                  default:
                          if (V_socket_hhh[HHOOK_SOCKET_OPT]->hhh_nhooks > 0)
                                  error = hhook_run_socket(so, sopt,
                                      HHOOK_SOCKET_OPT);
                          else
                                  error = ENOPROTOOPT;
                          break;
                  }
          }
  #ifdef MAC
  bad:
  #endif
          CURVNET_RESTORE();
          return (error);
  }
  
  int
  soopt_getm(struct sockopt *sopt, struct mbuf **mp)
  {
          struct mbuf *m, *m_prev;
          int sopt_size = sopt->sopt_valsize;
  
          MGET(m, sopt->sopt_td ? M_WAITOK : M_NOWAIT, MT_DATA);
          if (m == NULL)
                  return ENOBUFS;
          if (sopt_size > MLEN) {
                  MCLGET(m, sopt->sopt_td ? M_WAITOK : M_NOWAIT);
                  if ((m->m_flags & M_EXT) == 0) {
                          m_free(m);
                          return ENOBUFS;
                  }
                  m->m_len = min(MCLBYTES, sopt_size);
          } else {
                  m->m_len = min(MLEN, sopt_size);
          }
          sopt_size -= m->m_len;
          *mp = m;
          m_prev = m;
  
          while (sopt_size) {
                  MGET(m, sopt->sopt_td ? M_WAITOK : M_NOWAIT, MT_DATA);
                  if (m == NULL) {
                          m_freem(*mp);
                          return ENOBUFS;
                  }
                  if (sopt_size > MLEN) {
                          MCLGET(m, sopt->sopt_td != NULL ? M_WAITOK :
                              M_NOWAIT);
                          if ((m->m_flags & M_EXT) == 0) {
                                  m_freem(m);
                                  m_freem(*mp);
                                  return ENOBUFS;
                          }
                          m->m_len = min(MCLBYTES, sopt_size);
                  } else {
                          m->m_len = min(MLEN, sopt_size);
                  }
                  sopt_size -= m->m_len;
                  m_prev->m_next = m;
                  m_prev = m;
          }
          return (0);
  }
  
  int
  soopt_mcopyin(struct sockopt *sopt, struct mbuf *m)
  {
          struct mbuf *m0 = m;
  
          if (sopt->sopt_val == NULL)
                  return (0);
          while (m != NULL && sopt->sopt_valsize >= m->m_len) {
                  if (sopt->sopt_td != NULL) {
                          int error;
  
                          error = copyin(sopt->sopt_val, mtod(m, char *),
                              m->m_len);
                          if (error != 0) {
                                  m_freem(m0);
                                  return(error);
                          }
                  } else
                          bcopy(sopt->sopt_val, mtod(m, char *), m->m_len);
                  sopt->sopt_valsize -= m->m_len;
                  sopt->sopt_val = (char *)sopt->sopt_val + m->m_len;
                  m = m->m_next;
          }
          if (m != NULL) /* should be allocated enoughly at ip6_sooptmcopyin() */
                  panic("ip6_sooptmcopyin");
          return (0);
  }
  
  int
  soopt_mcopyout(struct sockopt *sopt, struct mbuf *m)
  {
          struct mbuf *m0 = m;
          size_t valsize = 0;
  
          if (sopt->sopt_val == NULL)
                  return (0);
          while (m != NULL && sopt->sopt_valsize >= m->m_len) {
                  if (sopt->sopt_td != NULL) {
                          int error;
  
                          error = copyout(mtod(m, char *), sopt->sopt_val,
                              m->m_len);
                          if (error != 0) {
                                  m_freem(m0);
                                  return(error);
                          }
                  } else
                          bcopy(mtod(m, char *), sopt->sopt_val, m->m_len);
                  sopt->sopt_valsize -= m->m_len;
                  sopt->sopt_val = (char *)sopt->sopt_val + m->m_len;
                  valsize += m->m_len;
                  m = m->m_next;
          }
          if (m != NULL) {
                  /* enough soopt buffer should be given from user-land */
                  m_freem(m0);
                  return(EINVAL);
          }
          sopt->sopt_valsize = valsize;
          return (0);
  }
  
  /*
   * sohasoutofband(): protocol notifies socket layer of the arrival of new
   * out-of-band data, which will then notify socket consumers.
   */
  void
  sohasoutofband(struct socket *so)
  {
  
          if (so->so_sigio != NULL)
                  pgsigio(&so->so_sigio, SIGURG, 0);
          selwakeuppri(&so->so_rdsel, PSOCK);
  }
  
  int
  sopoll(struct socket *so, int events, struct ucred *active_cred,
      struct thread *td)
  {
  
          /*
           * We do not need to set or assert curvnet as long as everyone uses
           * sopoll_generic().
           */
          return (so->so_proto->pr_sopoll(so, events, active_cred, td));
  }
  
  int
  sopoll_generic(struct socket *so, int events, struct ucred *active_cred,
      struct thread *td)
  {
          int revents;
  
          SOCK_LOCK(so);
          if (SOLISTENING(so)) {
                  if (!(events & (POLLIN | POLLRDNORM)))
                          revents = 0;
                  else if (!TAILQ_EMPTY(&so->sol_comp))
                          revents = events & (POLLIN | POLLRDNORM);
                  else if ((events & POLLINIGNEOF) == 0 && so->so_error)
                          revents = (events & (POLLIN | POLLRDNORM)) | POLLHUP;
                  else {
                          selrecord(td, &so->so_rdsel);
                          revents = 0;
                  }
          } else {
                  revents = 0;
                  SOCK_SENDBUF_LOCK(so);
                  SOCK_RECVBUF_LOCK(so);
                  if (events & (POLLIN | POLLRDNORM))
                          if (soreadabledata(so))
                                  revents |= events & (POLLIN | POLLRDNORM);
                  if (events & (POLLOUT | POLLWRNORM))
                          if (sowriteable(so))
                                  revents |= events & (POLLOUT | POLLWRNORM);
                  if (events & (POLLPRI | POLLRDBAND))
                          if (so->so_oobmark ||
                              (so->so_rcv.sb_state & SBS_RCVATMARK))
                                  revents |= events & (POLLPRI | POLLRDBAND);
                  if ((events & POLLINIGNEOF) == 0) {
                          if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
                                  revents |= events & (POLLIN | POLLRDNORM);
                                  if (so->so_snd.sb_state & SBS_CANTSENDMORE)
                                          revents |= POLLHUP;
                          }
                  }
                  if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
                          revents |= events & POLLRDHUP;
                  if (revents == 0) {
                          if (events &
                              (POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND | POLLRDHUP)) {
                                  selrecord(td, &so->so_rdsel);
                                  so->so_rcv.sb_flags |= SB_SEL;
                          }
                          if (events & (POLLOUT | POLLWRNORM)) {
                                  selrecord(td, &so->so_wrsel);
                                  so->so_snd.sb_flags |= SB_SEL;
                          }
                  }
                  SOCK_RECVBUF_UNLOCK(so);
                  SOCK_SENDBUF_UNLOCK(so);
          }
          SOCK_UNLOCK(so);
          return (revents);
  }
  
  int
  soo_kqfilter(struct file *fp, struct knote *kn)
  {
          struct socket *so = kn->kn_fp->f_data;
          struct sockbuf *sb;
          sb_which which;
          struct knlist *knl;
  
          switch (kn->kn_filter) {
          case EVFILT_READ:
                  kn->kn_fop = &soread_filtops;
                  knl = &so->so_rdsel.si_note;
                  sb = &so->so_rcv;
                  which = SO_RCV;
                  break;
          case EVFILT_WRITE:
                  kn->kn_fop = &sowrite_filtops;
                  knl = &so->so_wrsel.si_note;
                  sb = &so->so_snd;
                  which = SO_SND;
                  break;
          case EVFILT_EMPTY:
                  kn->kn_fop = &soempty_filtops;
                  knl = &so->so_wrsel.si_note;
                  sb = &so->so_snd;
                  which = SO_SND;
                  break;
          default:
                  return (EINVAL);
          }
  
          SOCK_LOCK(so);
          if (SOLISTENING(so)) {
                  knlist_add(knl, kn, 1);
          } else {
                  SOCK_BUF_LOCK(so, which);
                  knlist_add(knl, kn, 1);
                  sb->sb_flags |= SB_KNOTE;
                  SOCK_BUF_UNLOCK(so, which);
          }
          SOCK_UNLOCK(so);
          return (0);
  }
  
  static void
  filt_sordetach(struct knote *kn)
  {
          struct socket *so = kn->kn_fp->f_data;
  
          so_rdknl_lock(so);
          knlist_remove(&so->so_rdsel.si_note, kn, 1);
          if (!SOLISTENING(so) && knlist_empty(&so->so_rdsel.si_note))
                  so->so_rcv.sb_flags &= ~SB_KNOTE;
          so_rdknl_unlock(so);
  }
  
  /*ARGSUSED*/
  static int
  filt_soread(struct knote *kn, long hint)
  {
          struct socket *so;
  
          so = kn->kn_fp->f_data;
  
          if (SOLISTENING(so)) {
                  SOCK_LOCK_ASSERT(so);
                  kn->kn_data = so->sol_qlen;
                  if (so->so_error) {
                          kn->kn_flags |= EV_EOF;
                          kn->kn_fflags = so->so_error;
                          return (1);
                  }
                  return (!TAILQ_EMPTY(&so->sol_comp));
          }
  
          SOCK_RECVBUF_LOCK_ASSERT(so);
  
          kn->kn_data = sbavail(&so->so_rcv) - so->so_rcv.sb_ctl;
          if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
                  kn->kn_flags |= EV_EOF;
                  kn->kn_fflags = so->so_error;
                  return (1);
          } else if (so->so_error || so->so_rerror)
                  return (1);
  
          if (kn->kn_sfflags & NOTE_LOWAT) {
                  if (kn->kn_data >= kn->kn_sdata)
                          return (1);
          } else if (sbavail(&so->so_rcv) >= so->so_rcv.sb_lowat)
                  return (1);
  
          /* This hook returning non-zero indicates an event, not error */
          return (hhook_run_socket(so, NULL, HHOOK_FILT_SOREAD));
  }
  
  static void
  filt_sowdetach(struct knote *kn)
  {
          struct socket *so = kn->kn_fp->f_data;
  
          so_wrknl_lock(so);
          knlist_remove(&so->so_wrsel.si_note, kn, 1);
          if (!SOLISTENING(so) && knlist_empty(&so->so_wrsel.si_note))
                  so->so_snd.sb_flags &= ~SB_KNOTE;
          so_wrknl_unlock(so);
  }
  
  /*ARGSUSED*/
  static int
  filt_sowrite(struct knote *kn, long hint)
  {
          struct socket *so;
  
          so = kn->kn_fp->f_data;
  
          if (SOLISTENING(so))
                  return (0);
  
          SOCK_SENDBUF_LOCK_ASSERT(so);
          kn->kn_data = sbspace(&so->so_snd);
  
          hhook_run_socket(so, kn, HHOOK_FILT_SOWRITE);
  
          if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
                  kn->kn_flags |= EV_EOF;
                  kn->kn_fflags = so->so_error;
                  return (1);
          } else if (so->so_error)        /* temporary udp error */
                  return (1);
          else if (((so->so_state & SS_ISCONNECTED) == 0) &&
              (so->so_proto->pr_flags & PR_CONNREQUIRED))
                  return (0);
          else if (kn->kn_sfflags & NOTE_LOWAT)
                  return (kn->kn_data >= kn->kn_sdata);
          else
                  return (kn->kn_data >= so->so_snd.sb_lowat);
  }
  
  static int
  filt_soempty(struct knote *kn, long hint)
  {
          struct socket *so;
  
          so = kn->kn_fp->f_data;
  
          if (SOLISTENING(so))
                  return (1);
  
          SOCK_SENDBUF_LOCK_ASSERT(so);
          kn->kn_data = sbused(&so->so_snd);
  
          if (kn->kn_data == 0)
                  return (1);
          else
                  return (0);
  }
  
  int
  socheckuid(struct socket *so, uid_t uid)
  {
  
          if (so == NULL)
                  return (EPERM);
          if (so->so_cred->cr_uid != uid)
                  return (EPERM);
          return (0);
  }
  
  /*
   * These functions are used by protocols to notify the socket layer (and its
   * consumers) of state changes in the sockets driven by protocol-side events.
   */
  
  /*
   * 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)
  {
  
          SOCK_LOCK(so);
          so->so_state &= ~(SS_ISCONNECTED|SS_ISDISCONNECTING);
          so->so_state |= SS_ISCONNECTING;
          SOCK_UNLOCK(so);
  }
  
  void
  soisconnected(struct socket *so)
  {
          bool last __diagused;
  
          SOCK_LOCK(so);
          so->so_state &= ~(SS_ISCONNECTING|SS_ISDISCONNECTING|SS_ISCONFIRMING);
          so->so_state |= SS_ISCONNECTED;
  
          if (so->so_qstate == SQ_INCOMP) {
                  struct socket *head = so->so_listen;
                  int ret;
  
                  KASSERT(head, ("%s: so %p on incomp of NULL", __func__, so));
                  /*
                   * Promoting a socket from incomplete queue to complete, we
                   * need to go through reverse order of locking.  We first do
                   * trylock, and if that doesn't succeed, we go the hard way
                   * leaving a reference and rechecking consistency after proper
                   * locking.
                   */
                  if (__predict_false(SOLISTEN_TRYLOCK(head) == 0)) {
                          soref(head);
                          SOCK_UNLOCK(so);
                          SOLISTEN_LOCK(head);
                          SOCK_LOCK(so);
                          if (__predict_false(head != so->so_listen)) {
                                  /*
                                   * The socket went off the listen queue,
                                   * should be lost race to close(2) of sol.
                                   * The socket is about to soabort().
                                   */
                                  SOCK_UNLOCK(so);
                                  sorele_locked(head);
                                  return;
                          }
                          last = refcount_release(&head->so_count);
                          KASSERT(!last, ("%s: released last reference for %p",
                              __func__, head));
                  }
  again:
                  if ((so->so_options & SO_ACCEPTFILTER) == 0) {
                          TAILQ_REMOVE(&head->sol_incomp, so, so_list);
                          head->sol_incqlen--;
                          TAILQ_INSERT_TAIL(&head->sol_comp, so, so_list);
                          head->sol_qlen++;
                          so->so_qstate = SQ_COMP;
                          SOCK_UNLOCK(so);
                          solisten_wakeup(head);  /* unlocks */
                  } else {
                          SOCK_RECVBUF_LOCK(so);
                          soupcall_set(so, SO_RCV,
                              head->sol_accept_filter->accf_callback,
                              head->sol_accept_filter_arg);
                          so->so_options &= ~SO_ACCEPTFILTER;
                          ret = head->sol_accept_filter->accf_callback(so,
                              head->sol_accept_filter_arg, M_NOWAIT);
                          if (ret == SU_ISCONNECTED) {
                                  soupcall_clear(so, SO_RCV);
                                  SOCK_RECVBUF_UNLOCK(so);
                                  goto again;
                          }
                          SOCK_RECVBUF_UNLOCK(so);
                          SOCK_UNLOCK(so);
                          SOLISTEN_UNLOCK(head);
                  }
                  return;
          }
          SOCK_UNLOCK(so);
          wakeup(&so->so_timeo);
          sorwakeup(so);
          sowwakeup(so);
  }
  
  void
  soisdisconnecting(struct socket *so)
  {
  
          SOCK_LOCK(so);
          so->so_state &= ~SS_ISCONNECTING;
          so->so_state |= SS_ISDISCONNECTING;
  
          if (!SOLISTENING(so)) {
                  SOCK_RECVBUF_LOCK(so);
                  socantrcvmore_locked(so);
                  SOCK_SENDBUF_LOCK(so);
                  socantsendmore_locked(so);
          }
          SOCK_UNLOCK(so);
          wakeup(&so->so_timeo);
  }
  
  void
  soisdisconnected(struct socket *so)
  {
  
          SOCK_LOCK(so);
  
          /*
           * There is at least one reader of so_state that does not
           * acquire socket lock, namely soreceive_generic().  Ensure
           * that it never sees all flags that track connection status
           * cleared, by ordering the update with a barrier semantic of
           * our release thread fence.
           */
          so->so_state |= SS_ISDISCONNECTED;
          atomic_thread_fence_rel();
          so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
  
          if (!SOLISTENING(so)) {
                  SOCK_UNLOCK(so);
                  SOCK_RECVBUF_LOCK(so);
                  socantrcvmore_locked(so);
                  SOCK_SENDBUF_LOCK(so);
                  sbdrop_locked(&so->so_snd, sbused(&so->so_snd));
                  socantsendmore_locked(so);
          } else
                  SOCK_UNLOCK(so);
          wakeup(&so->so_timeo);
  }
  
  int
  soiolock(struct socket *so, struct sx *sx, int flags)
  {
          int error;
  
          KASSERT((flags & SBL_VALID) == flags,
              ("soiolock: invalid flags %#x", flags));
  
          if ((flags & SBL_WAIT) != 0) {
                  if ((flags & SBL_NOINTR) != 0) {
                          sx_xlock(sx);
                  } else {
                          error = sx_xlock_sig(sx);
                          if (error != 0)
                                  return (error);
                  }
          } else if (!sx_try_xlock(sx)) {
                  return (EWOULDBLOCK);
          }
  
          if (__predict_false(SOLISTENING(so))) {
                  sx_xunlock(sx);
                  return (ENOTCONN);
          }
          return (0);
  }
  
  void
  soiounlock(struct sx *sx)
  {
          sx_xunlock(sx);
  }
  
  /*
   * Make a copy of a sockaddr in a malloced buffer of type M_SONAME.
   */
  struct sockaddr *
  sodupsockaddr(const struct sockaddr *sa, int mflags)
  {
          struct sockaddr *sa2;
  
          sa2 = malloc(sa->sa_len, M_SONAME, mflags);
          if (sa2)
                  bcopy(sa, sa2, sa->sa_len);
          return sa2;
  }
  
  /*
   * Register per-socket destructor.
   */
  void
  sodtor_set(struct socket *so, so_dtor_t *func)
  {
  
          SOCK_LOCK_ASSERT(so);
          so->so_dtor = func;
  }
  
  /*
   * Register per-socket buffer upcalls.
   */
  void
  soupcall_set(struct socket *so, sb_which which, so_upcall_t func, void *arg)
  {
          struct sockbuf *sb;
  
          KASSERT(!SOLISTENING(so), ("%s: so %p listening", __func__, so));
  
          switch (which) {
          case SO_RCV:
                  sb = &so->so_rcv;
                  break;
          case SO_SND:
                  sb = &so->so_snd;
                  break;
          }
          SOCK_BUF_LOCK_ASSERT(so, which);
          sb->sb_upcall = func;
          sb->sb_upcallarg = arg;
          sb->sb_flags |= SB_UPCALL;
  }
  
  void
  soupcall_clear(struct socket *so, sb_which which)
  {
          struct sockbuf *sb;
  
          KASSERT(!SOLISTENING(so), ("%s: so %p listening", __func__, so));
  
          switch (which) {
          case SO_RCV:
                  sb = &so->so_rcv;
                  break;
          case SO_SND:
                  sb = &so->so_snd;
                  break;
          }
          SOCK_BUF_LOCK_ASSERT(so, which);
          KASSERT(sb->sb_upcall != NULL,
              ("%s: so %p no upcall to clear", __func__, so));
          sb->sb_upcall = NULL;
          sb->sb_upcallarg = NULL;
          sb->sb_flags &= ~SB_UPCALL;
  }
  
  void
  solisten_upcall_set(struct socket *so, so_upcall_t func, void *arg)
  {
  
          SOLISTEN_LOCK_ASSERT(so);
          so->sol_upcall = func;
          so->sol_upcallarg = arg;
  }
  
  static void
  so_rdknl_lock(void *arg)
  {
          struct socket *so = arg;
  
  retry:
          if (SOLISTENING(so)) {
                  SOLISTEN_LOCK(so);
          } else {
                  SOCK_RECVBUF_LOCK(so);
                  if (__predict_false(SOLISTENING(so))) {
                          SOCK_RECVBUF_UNLOCK(so);
                          goto retry;
                  }
          }
  }
  
  static void
  so_rdknl_unlock(void *arg)
  {
          struct socket *so = arg;
  
          if (SOLISTENING(so))
                  SOLISTEN_UNLOCK(so);
          else
                  SOCK_RECVBUF_UNLOCK(so);
  }
  
  static void
  so_rdknl_assert_lock(void *arg, int what)
  {
          struct socket *so = arg;
  
          if (what == LA_LOCKED) {
                  if (SOLISTENING(so))
                          SOLISTEN_LOCK_ASSERT(so);
                  else
                          SOCK_RECVBUF_LOCK_ASSERT(so);
          } else {
                  if (SOLISTENING(so))
                          SOLISTEN_UNLOCK_ASSERT(so);
                  else
                          SOCK_RECVBUF_UNLOCK_ASSERT(so);
          }
  }
  
  static void
  so_wrknl_lock(void *arg)
  {
          struct socket *so = arg;
  
  retry:
          if (SOLISTENING(so)) {
                  SOLISTEN_LOCK(so);
          } else {
                  SOCK_SENDBUF_LOCK(so);
                  if (__predict_false(SOLISTENING(so))) {
                          SOCK_SENDBUF_UNLOCK(so);
                          goto retry;
                  }
          }
  }
  
  static void
  so_wrknl_unlock(void *arg)
  {
          struct socket *so = arg;
  
          if (SOLISTENING(so))
                  SOLISTEN_UNLOCK(so);
          else
                  SOCK_SENDBUF_UNLOCK(so);
  }
  
  static void
  so_wrknl_assert_lock(void *arg, int what)
  {
          struct socket *so = arg;
  
          if (what == LA_LOCKED) {
                  if (SOLISTENING(so))
                          SOLISTEN_LOCK_ASSERT(so);
                  else
                          SOCK_SENDBUF_LOCK_ASSERT(so);
          } else {
                  if (SOLISTENING(so))
                          SOLISTEN_UNLOCK_ASSERT(so);
                  else
                          SOCK_SENDBUF_UNLOCK_ASSERT(so);
          }
  }
  
  /*
   * 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)
  {
  
          bzero(xso, sizeof(*xso));
          xso->xso_len = sizeof *xso;
          xso->xso_so = (uintptr_t)so;
          xso->so_type = so->so_type;
          xso->so_options = so->so_options;
          xso->so_linger = so->so_linger;
          xso->so_state = so->so_state;
          xso->so_pcb = (uintptr_t)so->so_pcb;
          xso->xso_protocol = so->so_proto->pr_protocol;
          xso->xso_family = so->so_proto->pr_domain->dom_family;
          xso->so_timeo = so->so_timeo;
          xso->so_error = so->so_error;
          xso->so_uid = so->so_cred->cr_uid;
          xso->so_pgid = so->so_sigio ? so->so_sigio->sio_pgid : 0;
          if (SOLISTENING(so)) {
                  xso->so_qlen = so->sol_qlen;
                  xso->so_incqlen = so->sol_incqlen;
                  xso->so_qlimit = so->sol_qlimit;
                  xso->so_oobmark = 0;
          } else {
                  xso->so_state |= so->so_qstate;
                  xso->so_qlen = xso->so_incqlen = xso->so_qlimit = 0;
                  xso->so_oobmark = so->so_oobmark;
                  sbtoxsockbuf(&so->so_snd, &xso->so_snd);
                  sbtoxsockbuf(&so->so_rcv, &xso->so_rcv);
          }
  }
  
  struct sockbuf *
  so_sockbuf_rcv(struct socket *so)
  {
  
          return (&so->so_rcv);
  }
  
  struct sockbuf *
  so_sockbuf_snd(struct socket *so)
  {
  
          return (&so->so_snd);
  }
  
  int
  so_state_get(const struct socket *so)
  {
  
          return (so->so_state);
  }
  
  void
  so_state_set(struct socket *so, int val)
  {
  
          so->so_state = val;
  }
  
  int
  so_options_get(const struct socket *so)
  {
  
          return (so->so_options);
  }
  
  void
  so_options_set(struct socket *so, int val)
  {
  
          so->so_options = val;
  }
  
  int
  so_error_get(const struct socket *so)
  {
  
          return (so->so_error);
  }
  
  void
  so_error_set(struct socket *so, int val)
  {
  
          so->so_error = val;
  }
  
  int
  so_linger_get(const struct socket *so)
  {
  
          return (so->so_linger);
  }
  
  void
  so_linger_set(struct socket *so, int val)
  {
  
          KASSERT(val >= 0 && val <= USHRT_MAX && val <= (INT_MAX / hz),
              ("%s: val %d out of range", __func__, val));
  
          so->so_linger = val;
  }
  
  struct protosw *
  so_protosw_get(const struct socket *so)
  {
  
          return (so->so_proto);
  }
  
  void
  so_protosw_set(struct socket *so, struct protosw *val)
  {
  
          so->so_proto = val;
  }
  
  void
  so_sorwakeup(struct socket *so)
  {
  
          sorwakeup(so);
  }
  
  void
  so_sowwakeup(struct socket *so)
  {
  
          sowwakeup(so);
  }
  
  void
  so_sorwakeup_locked(struct socket *so)
  {
  
          sorwakeup_locked(so);
  }
  
  void
  so_sowwakeup_locked(struct socket *so)
  {
  
          sowwakeup_locked(so);
  }
  
  void
  so_lock(struct socket *so)
  {
  
          SOCK_LOCK(so);
  }
  
  void
  so_unlock(struct socket *so)
  {
  
          SOCK_UNLOCK(so);
  }