The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1991, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD$");
   34 
   35 #include "opt_mac.h"
   36 #include "opt_param.h"
   37 #include "opt_mbuf_stress_test.h"
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/kernel.h>
   42 #include <sys/limits.h>
   43 #include <sys/lock.h>
   44 #include <sys/malloc.h>
   45 #include <sys/mbuf.h>
   46 #include <sys/sysctl.h>
   47 #include <sys/domain.h>
   48 #include <sys/protosw.h>
   49 #include <sys/uio.h>
   50 
   51 #include <security/mac/mac_framework.h>
   52 
   53 int     max_linkhdr;
   54 int     max_protohdr;
   55 int     max_hdr;
   56 int     max_datalen;
   57 #ifdef MBUF_STRESS_TEST
   58 int     m_defragpackets;
   59 int     m_defragbytes;
   60 int     m_defraguseless;
   61 int     m_defragfailure;
   62 int     m_defragrandomfailures;
   63 #endif
   64 
   65 /*
   66  * sysctl(8) exported objects
   67  */
   68 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RD,
   69            &max_linkhdr, 0, "Size of largest link layer header");
   70 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RD,
   71            &max_protohdr, 0, "Size of largest protocol layer header");
   72 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RD,
   73            &max_hdr, 0, "Size of largest link plus protocol header");
   74 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RD,
   75            &max_datalen, 0, "Minimum space left in mbuf after max_hdr");
   76 #ifdef MBUF_STRESS_TEST
   77 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD,
   78            &m_defragpackets, 0, "");
   79 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD,
   80            &m_defragbytes, 0, "");
   81 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD,
   82            &m_defraguseless, 0, "");
   83 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD,
   84            &m_defragfailure, 0, "");
   85 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW,
   86            &m_defragrandomfailures, 0, "");
   87 #endif
   88 
   89 /*
   90  * Allocate a given length worth of mbufs and/or clusters (whatever fits
   91  * best) and return a pointer to the top of the allocated chain.  If an
   92  * existing mbuf chain is provided, then we will append the new chain
   93  * to the existing one but still return the top of the newly allocated
   94  * chain.
   95  */
   96 struct mbuf *
   97 m_getm2(struct mbuf *m, int len, int how, short type, int flags)
   98 {
   99         struct mbuf *mb, *nm = NULL, *mtail = NULL;
  100 
  101         KASSERT(len >= 0, ("%s: len is < 0", __func__));
  102 
  103         /* Validate flags. */
  104         flags &= (M_PKTHDR | M_EOR);
  105 
  106         /* Packet header mbuf must be first in chain. */
  107         if ((flags & M_PKTHDR) && m != NULL)
  108                 flags &= ~M_PKTHDR;
  109 
  110         /* Loop and append maximum sized mbufs to the chain tail. */
  111         while (len > 0) {
  112                 if (len > MCLBYTES)
  113                         mb = m_getjcl(how, type, (flags & M_PKTHDR),
  114                             MJUMPAGESIZE);
  115                 else if (len >= MINCLSIZE)
  116                         mb = m_getcl(how, type, (flags & M_PKTHDR));
  117                 else if (flags & M_PKTHDR)
  118                         mb = m_gethdr(how, type);
  119                 else
  120                         mb = m_get(how, type);
  121 
  122                 /* Fail the whole operation if one mbuf can't be allocated. */
  123                 if (mb == NULL) {
  124                         if (nm != NULL)
  125                                 m_freem(nm);
  126                         return (NULL);
  127                 }
  128 
  129                 /* Book keeping. */
  130                 len -= (mb->m_flags & M_EXT) ? mb->m_ext.ext_size :
  131                         ((mb->m_flags & M_PKTHDR) ? MHLEN : MLEN);
  132                 if (mtail != NULL)
  133                         mtail->m_next = mb;
  134                 else
  135                         nm = mb;
  136                 mtail = mb;
  137                 flags &= ~M_PKTHDR;     /* Only valid on the first mbuf. */
  138         }
  139         if (flags & M_EOR)
  140                 mtail->m_flags |= M_EOR;  /* Only valid on the last mbuf. */
  141 
  142         /* If mbuf was supplied, append new chain to the end of it. */
  143         if (m != NULL) {
  144                 for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next)
  145                         ;
  146                 mtail->m_next = nm;
  147                 mtail->m_flags &= ~M_EOR;
  148         } else
  149                 m = nm;
  150 
  151         return (m);
  152 }
  153 
  154 /*
  155  * Free an entire chain of mbufs and associated external buffers, if
  156  * applicable.
  157  */
  158 void
  159 m_freem(struct mbuf *mb)
  160 {
  161 
  162         while (mb != NULL)
  163                 mb = m_free(mb);
  164 }
  165 
  166 /*-
  167  * Configure a provided mbuf to refer to the provided external storage
  168  * buffer and setup a reference count for said buffer.  If the setting
  169  * up of the reference count fails, the M_EXT bit will not be set.  If
  170  * successfull, the M_EXT bit is set in the mbuf's flags.
  171  *
  172  * Arguments:
  173  *    mb     The existing mbuf to which to attach the provided buffer.
  174  *    buf    The address of the provided external storage buffer.
  175  *    size   The size of the provided buffer.
  176  *    freef  A pointer to a routine that is responsible for freeing the
  177  *           provided external storage buffer.
  178  *    args   A pointer to an argument structure (of any type) to be passed
  179  *           to the provided freef routine (may be NULL).
  180  *    flags  Any other flags to be passed to the provided mbuf.
  181  *    type   The type that the external storage buffer should be
  182  *           labeled with.
  183  *
  184  * Returns:
  185  *    Nothing.
  186  */
  187 void
  188 m_extadd(struct mbuf *mb, caddr_t buf, u_int size,
  189     void (*freef)(void *, void *), void *args, int flags, int type)
  190 {
  191         KASSERT(type != EXT_CLUSTER, ("%s: EXT_CLUSTER not allowed", __func__));
  192 
  193         if (type != EXT_EXTREF)
  194                 mb->m_ext.ref_cnt = (u_int *)uma_zalloc(zone_ext_refcnt, M_NOWAIT);
  195         if (mb->m_ext.ref_cnt != NULL) {
  196                 *(mb->m_ext.ref_cnt) = 1;
  197                 mb->m_flags |= (M_EXT | flags);
  198                 mb->m_ext.ext_buf = buf;
  199                 mb->m_data = mb->m_ext.ext_buf;
  200                 mb->m_ext.ext_size = size;
  201                 mb->m_ext.ext_free = freef;
  202                 mb->m_ext.ext_args = args;
  203                 mb->m_ext.ext_type = type;
  204         }
  205 }
  206 
  207 /*
  208  * Non-directly-exported function to clean up after mbufs with M_EXT
  209  * storage attached to them if the reference count hits 1.
  210  */
  211 void
  212 mb_free_ext(struct mbuf *m)
  213 {
  214         int skipmbuf;
  215         
  216         KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
  217         KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
  218 
  219 
  220         /*
  221          * check if the header is embedded in the cluster
  222          */     
  223         skipmbuf = (m->m_flags & M_NOFREE);
  224         
  225         /* Free attached storage if this mbuf is the only reference to it. */
  226         if (*(m->m_ext.ref_cnt) == 1 ||
  227             atomic_fetchadd_int(m->m_ext.ref_cnt, -1) == 1) {
  228                 switch (m->m_ext.ext_type) {
  229                 case EXT_PACKET:        /* The packet zone is special. */
  230                         if (*(m->m_ext.ref_cnt) == 0)
  231                                 *(m->m_ext.ref_cnt) = 1;
  232                         uma_zfree(zone_pack, m);
  233                         return;         /* Job done. */
  234                 case EXT_CLUSTER:
  235                         uma_zfree(zone_clust, m->m_ext.ext_buf);
  236                         break;
  237                 case EXT_JUMBOP:
  238                         uma_zfree(zone_jumbop, m->m_ext.ext_buf);
  239                         break;
  240                 case EXT_JUMBO9:
  241                         uma_zfree(zone_jumbo9, m->m_ext.ext_buf);
  242                         break;
  243                 case EXT_JUMBO16:
  244                         uma_zfree(zone_jumbo16, m->m_ext.ext_buf);
  245                         break;
  246                 case EXT_SFBUF:
  247                 case EXT_NET_DRV:
  248                 case EXT_MOD_TYPE:
  249                 case EXT_DISPOSABLE:
  250                         *(m->m_ext.ref_cnt) = 0;
  251                         uma_zfree(zone_ext_refcnt, __DEVOLATILE(u_int *,
  252                                 m->m_ext.ref_cnt));
  253                         /* FALLTHROUGH */
  254                 case EXT_EXTREF:
  255                         KASSERT(m->m_ext.ext_free != NULL,
  256                                 ("%s: ext_free not set", __func__));
  257                         (*(m->m_ext.ext_free))(m->m_ext.ext_buf,
  258                             m->m_ext.ext_args);
  259                         break;
  260                 default:
  261                         KASSERT(m->m_ext.ext_type == 0,
  262                                 ("%s: unknown ext_type", __func__));
  263                 }
  264         }
  265         if (skipmbuf)
  266                 return;
  267         
  268         /*
  269          * Free this mbuf back to the mbuf zone with all m_ext
  270          * information purged.
  271          */
  272         m->m_ext.ext_buf = NULL;
  273         m->m_ext.ext_free = NULL;
  274         m->m_ext.ext_args = NULL;
  275         m->m_ext.ref_cnt = NULL;
  276         m->m_ext.ext_size = 0;
  277         m->m_ext.ext_type = 0;
  278         m->m_flags &= ~M_EXT;
  279         uma_zfree(zone_mbuf, m);
  280 }
  281 
  282 /*
  283  * Attach the the cluster from *m to *n, set up m_ext in *n
  284  * and bump the refcount of the cluster.
  285  */
  286 static void
  287 mb_dupcl(struct mbuf *n, struct mbuf *m)
  288 {
  289         KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
  290         KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
  291         KASSERT((n->m_flags & M_EXT) == 0, ("%s: M_EXT set", __func__));
  292 
  293         if (*(m->m_ext.ref_cnt) == 1)
  294                 *(m->m_ext.ref_cnt) += 1;
  295         else
  296                 atomic_add_int(m->m_ext.ref_cnt, 1);
  297         n->m_ext.ext_buf = m->m_ext.ext_buf;
  298         n->m_ext.ext_free = m->m_ext.ext_free;
  299         n->m_ext.ext_args = m->m_ext.ext_args;
  300         n->m_ext.ext_size = m->m_ext.ext_size;
  301         n->m_ext.ref_cnt = m->m_ext.ref_cnt;
  302         n->m_ext.ext_type = m->m_ext.ext_type;
  303         n->m_flags |= M_EXT;
  304 }
  305 
  306 /*
  307  * Clean up mbuf (chain) from any tags and packet headers.
  308  * If "all" is set then the first mbuf in the chain will be
  309  * cleaned too.
  310  */
  311 void
  312 m_demote(struct mbuf *m0, int all)
  313 {
  314         struct mbuf *m;
  315 
  316         for (m = all ? m0 : m0->m_next; m != NULL; m = m->m_next) {
  317                 if (m->m_flags & M_PKTHDR) {
  318                         m_tag_delete_chain(m, NULL);
  319                         m->m_flags &= ~M_PKTHDR;
  320                         bzero(&m->m_pkthdr, sizeof(struct pkthdr));
  321                 }
  322                 if (m->m_type == MT_HEADER)
  323                         m->m_type = MT_DATA;
  324                 if (m != m0 && m->m_nextpkt != NULL)
  325                         m->m_nextpkt = NULL;
  326                 m->m_flags = m->m_flags & (M_EXT|M_EOR|M_RDONLY|M_FREELIST);
  327         }
  328 }
  329 
  330 /*
  331  * Sanity checks on mbuf (chain) for use in KASSERT() and general
  332  * debugging.
  333  * Returns 0 or panics when bad and 1 on all tests passed.
  334  * Sanitize, 0 to run M_SANITY_ACTION, 1 to garble things so they
  335  * blow up later.
  336  */
  337 int
  338 m_sanity(struct mbuf *m0, int sanitize)
  339 {
  340         struct mbuf *m;
  341         caddr_t a, b;
  342         int pktlen = 0;
  343 
  344 #ifdef INVARIANTS
  345 #define M_SANITY_ACTION(s)      panic("mbuf %p: " s, m)
  346 #else 
  347 #define M_SANITY_ACTION(s)      printf("mbuf %p: " s, m)
  348 #endif
  349 
  350         for (m = m0; m != NULL; m = m->m_next) {
  351                 /*
  352                  * Basic pointer checks.  If any of these fails then some
  353                  * unrelated kernel memory before or after us is trashed.
  354                  * No way to recover from that.
  355                  */
  356                 a = ((m->m_flags & M_EXT) ? m->m_ext.ext_buf :
  357                         ((m->m_flags & M_PKTHDR) ? (caddr_t)(&m->m_pktdat) :
  358                          (caddr_t)(&m->m_dat)) );
  359                 b = (caddr_t)(a + (m->m_flags & M_EXT ? m->m_ext.ext_size :
  360                         ((m->m_flags & M_PKTHDR) ? MHLEN : MLEN)));
  361                 if ((caddr_t)m->m_data < a)
  362                         M_SANITY_ACTION("m_data outside mbuf data range left");
  363                 if ((caddr_t)m->m_data > b)
  364                         M_SANITY_ACTION("m_data outside mbuf data range right");
  365                 if ((caddr_t)m->m_data + m->m_len > b)
  366                         M_SANITY_ACTION("m_data + m_len exeeds mbuf space");
  367                 if ((m->m_flags & M_PKTHDR) && m->m_pkthdr.header) {
  368                         if ((caddr_t)m->m_pkthdr.header < a ||
  369                             (caddr_t)m->m_pkthdr.header > b)
  370                                 M_SANITY_ACTION("m_pkthdr.header outside mbuf data range");
  371                 }
  372 
  373                 /* m->m_nextpkt may only be set on first mbuf in chain. */
  374                 if (m != m0 && m->m_nextpkt != NULL) {
  375                         if (sanitize) {
  376                                 m_freem(m->m_nextpkt);
  377                                 m->m_nextpkt = (struct mbuf *)0xDEADC0DE;
  378                         } else
  379                                 M_SANITY_ACTION("m->m_nextpkt on in-chain mbuf");
  380                 }
  381 
  382                 /* packet length (not mbuf length!) calculation */
  383                 if (m0->m_flags & M_PKTHDR)
  384                         pktlen += m->m_len;
  385 
  386                 /* m_tags may only be attached to first mbuf in chain. */
  387                 if (m != m0 && m->m_flags & M_PKTHDR &&
  388                     !SLIST_EMPTY(&m->m_pkthdr.tags)) {
  389                         if (sanitize) {
  390                                 m_tag_delete_chain(m, NULL);
  391                                 /* put in 0xDEADC0DE perhaps? */
  392                         } else
  393                                 M_SANITY_ACTION("m_tags on in-chain mbuf");
  394                 }
  395 
  396                 /* M_PKTHDR may only be set on first mbuf in chain */
  397                 if (m != m0 && m->m_flags & M_PKTHDR) {
  398                         if (sanitize) {
  399                                 bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
  400                                 m->m_flags &= ~M_PKTHDR;
  401                                 /* put in 0xDEADCODE and leave hdr flag in */
  402                         } else
  403                                 M_SANITY_ACTION("M_PKTHDR on in-chain mbuf");
  404                 }
  405         }
  406         m = m0;
  407         if (pktlen && pktlen != m->m_pkthdr.len) {
  408                 if (sanitize)
  409                         m->m_pkthdr.len = 0;
  410                 else
  411                         M_SANITY_ACTION("m_pkthdr.len != mbuf chain length");
  412         }
  413         return 1;
  414 
  415 #undef  M_SANITY_ACTION
  416 }
  417 
  418 
  419 /*
  420  * "Move" mbuf pkthdr from "from" to "to".
  421  * "from" must have M_PKTHDR set, and "to" must be empty.
  422  */
  423 void
  424 m_move_pkthdr(struct mbuf *to, struct mbuf *from)
  425 {
  426 
  427 #if 0
  428         /* see below for why these are not enabled */
  429         M_ASSERTPKTHDR(to);
  430         /* Note: with MAC, this may not be a good assertion. */
  431         KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags),
  432             ("m_move_pkthdr: to has tags"));
  433 #endif
  434 #ifdef MAC
  435         /*
  436          * XXXMAC: It could be this should also occur for non-MAC?
  437          */
  438         if (to->m_flags & M_PKTHDR)
  439                 m_tag_delete_chain(to, NULL);
  440 #endif
  441         to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
  442         if ((to->m_flags & M_EXT) == 0)
  443                 to->m_data = to->m_pktdat;
  444         to->m_pkthdr = from->m_pkthdr;          /* especially tags */
  445         SLIST_INIT(&from->m_pkthdr.tags);       /* purge tags from src */
  446         from->m_flags &= ~M_PKTHDR;
  447 }
  448 
  449 /*
  450  * Duplicate "from"'s mbuf pkthdr in "to".
  451  * "from" must have M_PKTHDR set, and "to" must be empty.
  452  * In particular, this does a deep copy of the packet tags.
  453  */
  454 int
  455 m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how)
  456 {
  457 
  458 #if 0
  459         /*
  460          * The mbuf allocator only initializes the pkthdr
  461          * when the mbuf is allocated with MGETHDR. Many users
  462          * (e.g. m_copy*, m_prepend) use MGET and then
  463          * smash the pkthdr as needed causing these
  464          * assertions to trip.  For now just disable them.
  465          */
  466         M_ASSERTPKTHDR(to);
  467         /* Note: with MAC, this may not be a good assertion. */
  468         KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags"));
  469 #endif
  470         MBUF_CHECKSLEEP(how);
  471 #ifdef MAC
  472         if (to->m_flags & M_PKTHDR)
  473                 m_tag_delete_chain(to, NULL);
  474 #endif
  475         to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
  476         if ((to->m_flags & M_EXT) == 0)
  477                 to->m_data = to->m_pktdat;
  478         to->m_pkthdr = from->m_pkthdr;
  479         SLIST_INIT(&to->m_pkthdr.tags);
  480         return (m_tag_copy_chain(to, from, MBTOM(how)));
  481 }
  482 
  483 /*
  484  * Lesser-used path for M_PREPEND:
  485  * allocate new mbuf to prepend to chain,
  486  * copy junk along.
  487  */
  488 struct mbuf *
  489 m_prepend(struct mbuf *m, int len, int how)
  490 {
  491         struct mbuf *mn;
  492 
  493         if (m->m_flags & M_PKTHDR)
  494                 MGETHDR(mn, how, m->m_type);
  495         else
  496                 MGET(mn, how, m->m_type);
  497         if (mn == NULL) {
  498                 m_freem(m);
  499                 return (NULL);
  500         }
  501         if (m->m_flags & M_PKTHDR)
  502                 M_MOVE_PKTHDR(mn, m);
  503         mn->m_next = m;
  504         m = mn;
  505         if(m->m_flags & M_PKTHDR) {
  506                 if (len < MHLEN)
  507                         MH_ALIGN(m, len);
  508         } else {
  509                 if (len < MLEN) 
  510                         M_ALIGN(m, len);
  511         }
  512         m->m_len = len;
  513         return (m);
  514 }
  515 
  516 /*
  517  * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
  518  * continuing for "len" bytes.  If len is M_COPYALL, copy to end of mbuf.
  519  * The wait parameter is a choice of M_TRYWAIT/M_DONTWAIT from caller.
  520  * Note that the copy is read-only, because clusters are not copied,
  521  * only their reference counts are incremented.
  522  */
  523 struct mbuf *
  524 m_copym(struct mbuf *m, int off0, int len, int wait)
  525 {
  526         struct mbuf *n, **np;
  527         int off = off0;
  528         struct mbuf *top;
  529         int copyhdr = 0;
  530 
  531         KASSERT(off >= 0, ("m_copym, negative off %d", off));
  532         KASSERT(len >= 0, ("m_copym, negative len %d", len));
  533         MBUF_CHECKSLEEP(wait);
  534         if (off == 0 && m->m_flags & M_PKTHDR)
  535                 copyhdr = 1;
  536         while (off > 0) {
  537                 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
  538                 if (off < m->m_len)
  539                         break;
  540                 off -= m->m_len;
  541                 m = m->m_next;
  542         }
  543         np = &top;
  544         top = 0;
  545         while (len > 0) {
  546                 if (m == NULL) {
  547                         KASSERT(len == M_COPYALL, 
  548                             ("m_copym, length > size of mbuf chain"));
  549                         break;
  550                 }
  551                 if (copyhdr)
  552                         MGETHDR(n, wait, m->m_type);
  553                 else
  554                         MGET(n, wait, m->m_type);
  555                 *np = n;
  556                 if (n == NULL)
  557                         goto nospace;
  558                 if (copyhdr) {
  559                         if (!m_dup_pkthdr(n, m, wait))
  560                                 goto nospace;
  561                         if (len == M_COPYALL)
  562                                 n->m_pkthdr.len -= off0;
  563                         else
  564                                 n->m_pkthdr.len = len;
  565                         copyhdr = 0;
  566                 }
  567                 n->m_len = min(len, m->m_len - off);
  568                 if (m->m_flags & M_EXT) {
  569                         n->m_data = m->m_data + off;
  570                         mb_dupcl(n, m);
  571                 } else
  572                         bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
  573                             (u_int)n->m_len);
  574                 if (len != M_COPYALL)
  575                         len -= n->m_len;
  576                 off = 0;
  577                 m = m->m_next;
  578                 np = &n->m_next;
  579         }
  580         if (top == NULL)
  581                 mbstat.m_mcfail++;      /* XXX: No consistency. */
  582 
  583         return (top);
  584 nospace:
  585         m_freem(top);
  586         mbstat.m_mcfail++;      /* XXX: No consistency. */
  587         return (NULL);
  588 }
  589 
  590 /*
  591  * Returns mbuf chain with new head for the prepending case.
  592  * Copies from mbuf (chain) n from off for len to mbuf (chain) m
  593  * either prepending or appending the data.
  594  * The resulting mbuf (chain) m is fully writeable.
  595  * m is destination (is made writeable)
  596  * n is source, off is offset in source, len is len from offset
  597  * dir, 0 append, 1 prepend
  598  * how, wait or nowait
  599  */
  600 
  601 static int
  602 m_bcopyxxx(void *s, void *t, u_int len)
  603 {
  604         bcopy(s, t, (size_t)len);
  605         return 0;
  606 }
  607 
  608 struct mbuf *
  609 m_copymdata(struct mbuf *m, struct mbuf *n, int off, int len,
  610     int prep, int how)
  611 {
  612         struct mbuf *mm, *x, *z, *prev = NULL;
  613         caddr_t p;
  614         int i, nlen = 0;
  615         caddr_t buf[MLEN];
  616 
  617         KASSERT(m != NULL && n != NULL, ("m_copymdata, no target or source"));
  618         KASSERT(off >= 0, ("m_copymdata, negative off %d", off));
  619         KASSERT(len >= 0, ("m_copymdata, negative len %d", len));
  620         KASSERT(prep == 0 || prep == 1, ("m_copymdata, unknown direction %d", prep));
  621 
  622         mm = m;
  623         if (!prep) {
  624                 while(mm->m_next) {
  625                         prev = mm;
  626                         mm = mm->m_next;
  627                 }
  628         }
  629         for (z = n; z != NULL; z = z->m_next)
  630                 nlen += z->m_len;
  631         if (len == M_COPYALL)
  632                 len = nlen - off;
  633         if (off + len > nlen || len < 1)
  634                 return NULL;
  635 
  636         if (!M_WRITABLE(mm)) {
  637                 /* XXX: Use proper m_xxx function instead. */
  638                 x = m_getcl(how, MT_DATA, mm->m_flags);
  639                 if (x == NULL)
  640                         return NULL;
  641                 bcopy(mm->m_ext.ext_buf, x->m_ext.ext_buf, x->m_ext.ext_size);
  642                 p = x->m_ext.ext_buf + (mm->m_data - mm->m_ext.ext_buf);
  643                 x->m_data = p;
  644                 mm->m_next = NULL;
  645                 if (mm != m)
  646                         prev->m_next = x;
  647                 m_free(mm);
  648                 mm = x;
  649         }
  650 
  651         /*
  652          * Append/prepend the data.  Allocating mbufs as necessary.
  653          */
  654         /* Shortcut if enough free space in first/last mbuf. */
  655         if (!prep && M_TRAILINGSPACE(mm) >= len) {
  656                 m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t) +
  657                          mm->m_len);
  658                 mm->m_len += len;
  659                 mm->m_pkthdr.len += len;
  660                 return m;
  661         }
  662         if (prep && M_LEADINGSPACE(mm) >= len) {
  663                 mm->m_data = mtod(mm, caddr_t) - len;
  664                 m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t));
  665                 mm->m_len += len;
  666                 mm->m_pkthdr.len += len;
  667                 return mm;
  668         }
  669 
  670         /* Expand first/last mbuf to cluster if possible. */
  671         if (!prep && !(mm->m_flags & M_EXT) && len > M_TRAILINGSPACE(mm)) {
  672                 bcopy(mm->m_data, &buf, mm->m_len);
  673                 m_clget(mm, how);
  674                 if (!(mm->m_flags & M_EXT))
  675                         return NULL;
  676                 bcopy(&buf, mm->m_ext.ext_buf, mm->m_len);
  677                 mm->m_data = mm->m_ext.ext_buf;
  678                 mm->m_pkthdr.header = NULL;
  679         }
  680         if (prep && !(mm->m_flags & M_EXT) && len > M_LEADINGSPACE(mm)) {
  681                 bcopy(mm->m_data, &buf, mm->m_len);
  682                 m_clget(mm, how);
  683                 if (!(mm->m_flags & M_EXT))
  684                         return NULL;
  685                 bcopy(&buf, (caddr_t *)mm->m_ext.ext_buf +
  686                        mm->m_ext.ext_size - mm->m_len, mm->m_len);
  687                 mm->m_data = (caddr_t)mm->m_ext.ext_buf +
  688                               mm->m_ext.ext_size - mm->m_len;
  689                 mm->m_pkthdr.header = NULL;
  690         }
  691 
  692         /* Append/prepend as many mbuf (clusters) as necessary to fit len. */
  693         if (!prep && len > M_TRAILINGSPACE(mm)) {
  694                 if (!m_getm(mm, len - M_TRAILINGSPACE(mm), how, MT_DATA))
  695                         return NULL;
  696         }
  697         if (prep && len > M_LEADINGSPACE(mm)) {
  698                 if (!(z = m_getm(NULL, len - M_LEADINGSPACE(mm), how, MT_DATA)))
  699                         return NULL;
  700                 i = 0;
  701                 for (x = z; x != NULL; x = x->m_next) {
  702                         i += x->m_flags & M_EXT ? x->m_ext.ext_size :
  703                               (x->m_flags & M_PKTHDR ? MHLEN : MLEN);
  704                         if (!x->m_next)
  705                                 break;
  706                 }
  707                 z->m_data += i - len;
  708                 m_move_pkthdr(mm, z);
  709                 x->m_next = mm;
  710                 mm = z;
  711         }
  712 
  713         /* Seek to start position in source mbuf. Optimization for long chains. */
  714         while (off > 0) {
  715                 if (off < n->m_len)
  716                         break;
  717                 off -= n->m_len;
  718                 n = n->m_next;
  719         }
  720 
  721         /* Copy data into target mbuf. */
  722         z = mm;
  723         while (len > 0) {
  724                 KASSERT(z != NULL, ("m_copymdata, falling off target edge"));
  725                 i = M_TRAILINGSPACE(z);
  726                 m_apply(n, off, i, m_bcopyxxx, mtod(z, caddr_t) + z->m_len);
  727                 z->m_len += i;
  728                 /* fixup pkthdr.len if necessary */
  729                 if ((prep ? mm : m)->m_flags & M_PKTHDR)
  730                         (prep ? mm : m)->m_pkthdr.len += i;
  731                 off += i;
  732                 len -= i;
  733                 z = z->m_next;
  734         }
  735         return (prep ? mm : m);
  736 }
  737 
  738 /*
  739  * Copy an entire packet, including header (which must be present).
  740  * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'.
  741  * Note that the copy is read-only, because clusters are not copied,
  742  * only their reference counts are incremented.
  743  * Preserve alignment of the first mbuf so if the creator has left
  744  * some room at the beginning (e.g. for inserting protocol headers)
  745  * the copies still have the room available.
  746  */
  747 struct mbuf *
  748 m_copypacket(struct mbuf *m, int how)
  749 {
  750         struct mbuf *top, *n, *o;
  751 
  752         MBUF_CHECKSLEEP(how);
  753         MGET(n, how, m->m_type);
  754         top = n;
  755         if (n == NULL)
  756                 goto nospace;
  757 
  758         if (!m_dup_pkthdr(n, m, how))
  759                 goto nospace;
  760         n->m_len = m->m_len;
  761         if (m->m_flags & M_EXT) {
  762                 n->m_data = m->m_data;
  763                 mb_dupcl(n, m);
  764         } else {
  765                 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat );
  766                 bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
  767         }
  768 
  769         m = m->m_next;
  770         while (m) {
  771                 MGET(o, how, m->m_type);
  772                 if (o == NULL)
  773                         goto nospace;
  774 
  775                 n->m_next = o;
  776                 n = n->m_next;
  777 
  778                 n->m_len = m->m_len;
  779                 if (m->m_flags & M_EXT) {
  780                         n->m_data = m->m_data;
  781                         mb_dupcl(n, m);
  782                 } else {
  783                         bcopy(mtod(m, char *), mtod(n, char *), n->m_len);
  784                 }
  785 
  786                 m = m->m_next;
  787         }
  788         return top;
  789 nospace:
  790         m_freem(top);
  791         mbstat.m_mcfail++;      /* XXX: No consistency. */ 
  792         return (NULL);
  793 }
  794 
  795 /*
  796  * Copy data from an mbuf chain starting "off" bytes from the beginning,
  797  * continuing for "len" bytes, into the indicated buffer.
  798  */
  799 void
  800 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp)
  801 {
  802         u_int count;
  803 
  804         KASSERT(off >= 0, ("m_copydata, negative off %d", off));
  805         KASSERT(len >= 0, ("m_copydata, negative len %d", len));
  806         while (off > 0) {
  807                 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
  808                 if (off < m->m_len)
  809                         break;
  810                 off -= m->m_len;
  811                 m = m->m_next;
  812         }
  813         while (len > 0) {
  814                 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
  815                 count = min(m->m_len - off, len);
  816                 bcopy(mtod(m, caddr_t) + off, cp, count);
  817                 len -= count;
  818                 cp += count;
  819                 off = 0;
  820                 m = m->m_next;
  821         }
  822 }
  823 
  824 /*
  825  * Copy a packet header mbuf chain into a completely new chain, including
  826  * copying any mbuf clusters.  Use this instead of m_copypacket() when
  827  * you need a writable copy of an mbuf chain.
  828  */
  829 struct mbuf *
  830 m_dup(struct mbuf *m, int how)
  831 {
  832         struct mbuf **p, *top = NULL;
  833         int remain, moff, nsize;
  834 
  835         MBUF_CHECKSLEEP(how);
  836         /* Sanity check */
  837         if (m == NULL)
  838                 return (NULL);
  839         M_ASSERTPKTHDR(m);
  840 
  841         /* While there's more data, get a new mbuf, tack it on, and fill it */
  842         remain = m->m_pkthdr.len;
  843         moff = 0;
  844         p = &top;
  845         while (remain > 0 || top == NULL) {     /* allow m->m_pkthdr.len == 0 */
  846                 struct mbuf *n;
  847 
  848                 /* Get the next new mbuf */
  849                 if (remain >= MINCLSIZE) {
  850                         n = m_getcl(how, m->m_type, 0);
  851                         nsize = MCLBYTES;
  852                 } else {
  853                         n = m_get(how, m->m_type);
  854                         nsize = MLEN;
  855                 }
  856                 if (n == NULL)
  857                         goto nospace;
  858 
  859                 if (top == NULL) {              /* First one, must be PKTHDR */
  860                         if (!m_dup_pkthdr(n, m, how)) {
  861                                 m_free(n);
  862                                 goto nospace;
  863                         }
  864                         if ((n->m_flags & M_EXT) == 0)
  865                                 nsize = MHLEN;
  866                 }
  867                 n->m_len = 0;
  868 
  869                 /* Link it into the new chain */
  870                 *p = n;
  871                 p = &n->m_next;
  872 
  873                 /* Copy data from original mbuf(s) into new mbuf */
  874                 while (n->m_len < nsize && m != NULL) {
  875                         int chunk = min(nsize - n->m_len, m->m_len - moff);
  876 
  877                         bcopy(m->m_data + moff, n->m_data + n->m_len, chunk);
  878                         moff += chunk;
  879                         n->m_len += chunk;
  880                         remain -= chunk;
  881                         if (moff == m->m_len) {
  882                                 m = m->m_next;
  883                                 moff = 0;
  884                         }
  885                 }
  886 
  887                 /* Check correct total mbuf length */
  888                 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL),
  889                         ("%s: bogus m_pkthdr.len", __func__));
  890         }
  891         return (top);
  892 
  893 nospace:
  894         m_freem(top);
  895         mbstat.m_mcfail++;      /* XXX: No consistency. */
  896         return (NULL);
  897 }
  898 
  899 /*
  900  * Concatenate mbuf chain n to m.
  901  * Both chains must be of the same type (e.g. MT_DATA).
  902  * Any m_pkthdr is not updated.
  903  */
  904 void
  905 m_cat(struct mbuf *m, struct mbuf *n)
  906 {
  907         while (m->m_next)
  908                 m = m->m_next;
  909         while (n) {
  910                 if (m->m_flags & M_EXT ||
  911                     m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) {
  912                         /* just join the two chains */
  913                         m->m_next = n;
  914                         return;
  915                 }
  916                 /* splat the data from one into the other */
  917                 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
  918                     (u_int)n->m_len);
  919                 m->m_len += n->m_len;
  920                 n = m_free(n);
  921         }
  922 }
  923 
  924 void
  925 m_adj(struct mbuf *mp, int req_len)
  926 {
  927         int len = req_len;
  928         struct mbuf *m;
  929         int count;
  930 
  931         if ((m = mp) == NULL)
  932                 return;
  933         if (len >= 0) {
  934                 /*
  935                  * Trim from head.
  936                  */
  937                 while (m != NULL && len > 0) {
  938                         if (m->m_len <= len) {
  939                                 len -= m->m_len;
  940                                 m->m_len = 0;
  941                                 m = m->m_next;
  942                         } else {
  943                                 m->m_len -= len;
  944                                 m->m_data += len;
  945                                 len = 0;
  946                         }
  947                 }
  948                 m = mp;
  949                 if (mp->m_flags & M_PKTHDR)
  950                         m->m_pkthdr.len -= (req_len - len);
  951         } else {
  952                 /*
  953                  * Trim from tail.  Scan the mbuf chain,
  954                  * calculating its length and finding the last mbuf.
  955                  * If the adjustment only affects this mbuf, then just
  956                  * adjust and return.  Otherwise, rescan and truncate
  957                  * after the remaining size.
  958                  */
  959                 len = -len;
  960                 count = 0;
  961                 for (;;) {
  962                         count += m->m_len;
  963                         if (m->m_next == (struct mbuf *)0)
  964                                 break;
  965                         m = m->m_next;
  966                 }
  967                 if (m->m_len >= len) {
  968                         m->m_len -= len;
  969                         if (mp->m_flags & M_PKTHDR)
  970                                 mp->m_pkthdr.len -= len;
  971                         return;
  972                 }
  973                 count -= len;
  974                 if (count < 0)
  975                         count = 0;
  976                 /*
  977                  * Correct length for chain is "count".
  978                  * Find the mbuf with last data, adjust its length,
  979                  * and toss data from remaining mbufs on chain.
  980                  */
  981                 m = mp;
  982                 if (m->m_flags & M_PKTHDR)
  983                         m->m_pkthdr.len = count;
  984                 for (; m; m = m->m_next) {
  985                         if (m->m_len >= count) {
  986                                 m->m_len = count;
  987                                 if (m->m_next != NULL) {
  988                                         m_freem(m->m_next);
  989                                         m->m_next = NULL;
  990                                 }
  991                                 break;
  992                         }
  993                         count -= m->m_len;
  994                 }
  995         }
  996 }
  997 
  998 /*
  999  * Rearange an mbuf chain so that len bytes are contiguous
 1000  * and in the data area of an mbuf (so that mtod and dtom
 1001  * will work for a structure of size len).  Returns the resulting
 1002  * mbuf chain on success, frees it and returns null on failure.
 1003  * If there is room, it will add up to max_protohdr-len extra bytes to the
 1004  * contiguous region in an attempt to avoid being called next time.
 1005  */
 1006 struct mbuf *
 1007 m_pullup(struct mbuf *n, int len)
 1008 {
 1009         struct mbuf *m;
 1010         int count;
 1011         int space;
 1012 
 1013         /*
 1014          * If first mbuf has no cluster, and has room for len bytes
 1015          * without shifting current data, pullup into it,
 1016          * otherwise allocate a new mbuf to prepend to the chain.
 1017          */
 1018         if ((n->m_flags & M_EXT) == 0 &&
 1019             n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
 1020                 if (n->m_len >= len)
 1021                         return (n);
 1022                 m = n;
 1023                 n = n->m_next;
 1024                 len -= m->m_len;
 1025         } else {
 1026                 if (len > MHLEN)
 1027                         goto bad;
 1028                 MGET(m, M_DONTWAIT, n->m_type);
 1029                 if (m == NULL)
 1030                         goto bad;
 1031                 m->m_len = 0;
 1032                 if (n->m_flags & M_PKTHDR)
 1033                         M_MOVE_PKTHDR(m, n);
 1034         }
 1035         space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
 1036         do {
 1037                 count = min(min(max(len, max_protohdr), space), n->m_len);
 1038                 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
 1039                   (u_int)count);
 1040                 len -= count;
 1041                 m->m_len += count;
 1042                 n->m_len -= count;
 1043                 space -= count;
 1044                 if (n->m_len)
 1045                         n->m_data += count;
 1046                 else
 1047                         n = m_free(n);
 1048         } while (len > 0 && n);
 1049         if (len > 0) {
 1050                 (void) m_free(m);
 1051                 goto bad;
 1052         }
 1053         m->m_next = n;
 1054         return (m);
 1055 bad:
 1056         m_freem(n);
 1057         mbstat.m_mpfail++;      /* XXX: No consistency. */
 1058         return (NULL);
 1059 }
 1060 
 1061 /*
 1062  * Like m_pullup(), except a new mbuf is always allocated, and we allow
 1063  * the amount of empty space before the data in the new mbuf to be specified
 1064  * (in the event that the caller expects to prepend later).
 1065  */
 1066 int MSFail;
 1067 
 1068 struct mbuf *
 1069 m_copyup(struct mbuf *n, int len, int dstoff)
 1070 {
 1071         struct mbuf *m;
 1072         int count, space;
 1073 
 1074         if (len > (MHLEN - dstoff))
 1075                 goto bad;
 1076         MGET(m, M_DONTWAIT, n->m_type);
 1077         if (m == NULL)
 1078                 goto bad;
 1079         m->m_len = 0;
 1080         if (n->m_flags & M_PKTHDR)
 1081                 M_MOVE_PKTHDR(m, n);
 1082         m->m_data += dstoff;
 1083         space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
 1084         do {
 1085                 count = min(min(max(len, max_protohdr), space), n->m_len);
 1086                 memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t),
 1087                     (unsigned)count);
 1088                 len -= count;
 1089                 m->m_len += count;
 1090                 n->m_len -= count;
 1091                 space -= count;
 1092                 if (n->m_len)
 1093                         n->m_data += count;
 1094                 else
 1095                         n = m_free(n);
 1096         } while (len > 0 && n);
 1097         if (len > 0) {
 1098                 (void) m_free(m);
 1099                 goto bad;
 1100         }
 1101         m->m_next = n;
 1102         return (m);
 1103  bad:
 1104         m_freem(n);
 1105         MSFail++;
 1106         return (NULL);
 1107 }
 1108 
 1109 /*
 1110  * Partition an mbuf chain in two pieces, returning the tail --
 1111  * all but the first len0 bytes.  In case of failure, it returns NULL and
 1112  * attempts to restore the chain to its original state.
 1113  *
 1114  * Note that the resulting mbufs might be read-only, because the new
 1115  * mbuf can end up sharing an mbuf cluster with the original mbuf if
 1116  * the "breaking point" happens to lie within a cluster mbuf. Use the
 1117  * M_WRITABLE() macro to check for this case.
 1118  */
 1119 struct mbuf *
 1120 m_split(struct mbuf *m0, int len0, int wait)
 1121 {
 1122         struct mbuf *m, *n;
 1123         u_int len = len0, remain;
 1124 
 1125         MBUF_CHECKSLEEP(wait);
 1126         for (m = m0; m && len > m->m_len; m = m->m_next)
 1127                 len -= m->m_len;
 1128         if (m == NULL)
 1129                 return (NULL);
 1130         remain = m->m_len - len;
 1131         if (m0->m_flags & M_PKTHDR) {
 1132                 MGETHDR(n, wait, m0->m_type);
 1133                 if (n == NULL)
 1134                         return (NULL);
 1135                 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
 1136                 n->m_pkthdr.len = m0->m_pkthdr.len - len0;
 1137                 m0->m_pkthdr.len = len0;
 1138                 if (m->m_flags & M_EXT)
 1139                         goto extpacket;
 1140                 if (remain > MHLEN) {
 1141                         /* m can't be the lead packet */
 1142                         MH_ALIGN(n, 0);
 1143                         n->m_next = m_split(m, len, wait);
 1144                         if (n->m_next == NULL) {
 1145                                 (void) m_free(n);
 1146                                 return (NULL);
 1147                         } else {
 1148                                 n->m_len = 0;
 1149                                 return (n);
 1150                         }
 1151                 } else
 1152                         MH_ALIGN(n, remain);
 1153         } else if (remain == 0) {
 1154                 n = m->m_next;
 1155                 m->m_next = NULL;
 1156                 return (n);
 1157         } else {
 1158                 MGET(n, wait, m->m_type);
 1159                 if (n == NULL)
 1160                         return (NULL);
 1161                 M_ALIGN(n, remain);
 1162         }
 1163 extpacket:
 1164         if (m->m_flags & M_EXT) {
 1165                 n->m_data = m->m_data + len;
 1166                 mb_dupcl(n, m);
 1167         } else {
 1168                 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
 1169         }
 1170         n->m_len = remain;
 1171         m->m_len = len;
 1172         n->m_next = m->m_next;
 1173         m->m_next = NULL;
 1174         return (n);
 1175 }
 1176 /*
 1177  * Routine to copy from device local memory into mbufs.
 1178  * Note that `off' argument is offset into first mbuf of target chain from
 1179  * which to begin copying the data to.
 1180  */
 1181 struct mbuf *
 1182 m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
 1183     void (*copy)(char *from, caddr_t to, u_int len))
 1184 {
 1185         struct mbuf *m;
 1186         struct mbuf *top = NULL, **mp = &top;
 1187         int len;
 1188 
 1189         if (off < 0 || off > MHLEN)
 1190                 return (NULL);
 1191 
 1192         while (totlen > 0) {
 1193                 if (top == NULL) {      /* First one, must be PKTHDR */
 1194                         if (totlen + off >= MINCLSIZE) {
 1195                                 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
 1196                                 len = MCLBYTES;
 1197                         } else {
 1198                                 m = m_gethdr(M_DONTWAIT, MT_DATA);
 1199                                 len = MHLEN;
 1200 
 1201                                 /* Place initial small packet/header at end of mbuf */
 1202                                 if (m && totlen + off + max_linkhdr <= MLEN) {
 1203                                         m->m_data += max_linkhdr;
 1204                                         len -= max_linkhdr;
 1205                                 }
 1206                         }
 1207                         if (m == NULL)
 1208                                 return NULL;
 1209                         m->m_pkthdr.rcvif = ifp;
 1210                         m->m_pkthdr.len = totlen;
 1211                 } else {
 1212                         if (totlen + off >= MINCLSIZE) {
 1213                                 m = m_getcl(M_DONTWAIT, MT_DATA, 0);
 1214                                 len = MCLBYTES;
 1215                         } else {
 1216                                 m = m_get(M_DONTWAIT, MT_DATA);
 1217                                 len = MLEN;
 1218                         }
 1219                         if (m == NULL) {
 1220                                 m_freem(top);
 1221                                 return NULL;
 1222                         }
 1223                 }
 1224                 if (off) {
 1225                         m->m_data += off;
 1226                         len -= off;
 1227                         off = 0;
 1228                 }
 1229                 m->m_len = len = min(totlen, len);
 1230                 if (copy)
 1231                         copy(buf, mtod(m, caddr_t), (u_int)len);
 1232                 else
 1233                         bcopy(buf, mtod(m, caddr_t), (u_int)len);
 1234                 buf += len;
 1235                 *mp = m;
 1236                 mp = &m->m_next;
 1237                 totlen -= len;
 1238         }
 1239         return (top);
 1240 }
 1241 
 1242 /*
 1243  * Copy data from a buffer back into the indicated mbuf chain,
 1244  * starting "off" bytes from the beginning, extending the mbuf
 1245  * chain if necessary.
 1246  */
 1247 void
 1248 m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp)
 1249 {
 1250         int mlen;
 1251         struct mbuf *m = m0, *n;
 1252         int totlen = 0;
 1253 
 1254         if (m0 == NULL)
 1255                 return;
 1256         while (off > (mlen = m->m_len)) {
 1257                 off -= mlen;
 1258                 totlen += mlen;
 1259                 if (m->m_next == NULL) {
 1260                         n = m_get(M_DONTWAIT, m->m_type);
 1261                         if (n == NULL)
 1262                                 goto out;
 1263                         bzero(mtod(n, caddr_t), MLEN);
 1264                         n->m_len = min(MLEN, len + off);
 1265                         m->m_next = n;
 1266                 }
 1267                 m = m->m_next;
 1268         }
 1269         while (len > 0) {
 1270                 mlen = min (m->m_len - off, len);
 1271                 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
 1272                 cp += mlen;
 1273                 len -= mlen;
 1274                 mlen += off;
 1275                 off = 0;
 1276                 totlen += mlen;
 1277                 if (len == 0)
 1278                         break;
 1279                 if (m->m_next == NULL) {
 1280                         n = m_get(M_DONTWAIT, m->m_type);
 1281                         if (n == NULL)
 1282                                 break;
 1283                         n->m_len = min(MLEN, len);
 1284                         m->m_next = n;
 1285                 }
 1286                 m = m->m_next;
 1287         }
 1288 out:    if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
 1289                 m->m_pkthdr.len = totlen;
 1290 }
 1291 
 1292 /*
 1293  * Append the specified data to the indicated mbuf chain,
 1294  * Extend the mbuf chain if the new data does not fit in
 1295  * existing space.
 1296  *
 1297  * Return 1 if able to complete the job; otherwise 0.
 1298  */
 1299 int
 1300 m_append(struct mbuf *m0, int len, c_caddr_t cp)
 1301 {
 1302         struct mbuf *m, *n;
 1303         int remainder, space;
 1304 
 1305         for (m = m0; m->m_next != NULL; m = m->m_next)
 1306                 ;
 1307         remainder = len;
 1308         space = M_TRAILINGSPACE(m);
 1309         if (space > 0) {
 1310                 /*
 1311                  * Copy into available space.
 1312                  */
 1313                 if (space > remainder)
 1314                         space = remainder;
 1315                 bcopy(cp, mtod(m, caddr_t) + m->m_len, space);
 1316                 m->m_len += space;
 1317                 cp += space, remainder -= space;
 1318         }
 1319         while (remainder > 0) {
 1320                 /*
 1321                  * Allocate a new mbuf; could check space
 1322                  * and allocate a cluster instead.
 1323                  */
 1324                 n = m_get(M_DONTWAIT, m->m_type);
 1325                 if (n == NULL)
 1326                         break;
 1327                 n->m_len = min(MLEN, remainder);
 1328                 bcopy(cp, mtod(n, caddr_t), n->m_len);
 1329                 cp += n->m_len, remainder -= n->m_len;
 1330                 m->m_next = n;
 1331                 m = n;
 1332         }
 1333         if (m0->m_flags & M_PKTHDR)
 1334                 m0->m_pkthdr.len += len - remainder;
 1335         return (remainder == 0);
 1336 }
 1337 
 1338 /*
 1339  * Apply function f to the data in an mbuf chain starting "off" bytes from
 1340  * the beginning, continuing for "len" bytes.
 1341  */
 1342 int
 1343 m_apply(struct mbuf *m, int off, int len,
 1344     int (*f)(void *, void *, u_int), void *arg)
 1345 {
 1346         u_int count;
 1347         int rval;
 1348 
 1349         KASSERT(off >= 0, ("m_apply, negative off %d", off));
 1350         KASSERT(len >= 0, ("m_apply, negative len %d", len));
 1351         while (off > 0) {
 1352                 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
 1353                 if (off < m->m_len)
 1354                         break;
 1355                 off -= m->m_len;
 1356                 m = m->m_next;
 1357         }
 1358         while (len > 0) {
 1359                 KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
 1360                 count = min(m->m_len - off, len);
 1361                 rval = (*f)(arg, mtod(m, caddr_t) + off, count);
 1362                 if (rval)
 1363                         return (rval);
 1364                 len -= count;
 1365                 off = 0;
 1366                 m = m->m_next;
 1367         }
 1368         return (0);
 1369 }
 1370 
 1371 /*
 1372  * Return a pointer to mbuf/offset of location in mbuf chain.
 1373  */
 1374 struct mbuf *
 1375 m_getptr(struct mbuf *m, int loc, int *off)
 1376 {
 1377 
 1378         while (loc >= 0) {
 1379                 /* Normal end of search. */
 1380                 if (m->m_len > loc) {
 1381                         *off = loc;
 1382                         return (m);
 1383                 } else {
 1384                         loc -= m->m_len;
 1385                         if (m->m_next == NULL) {
 1386                                 if (loc == 0) {
 1387                                         /* Point at the end of valid data. */
 1388                                         *off = m->m_len;
 1389                                         return (m);
 1390                                 }
 1391                                 return (NULL);
 1392                         }
 1393                         m = m->m_next;
 1394                 }
 1395         }
 1396         return (NULL);
 1397 }
 1398 
 1399 void
 1400 m_print(const struct mbuf *m, int maxlen)
 1401 {
 1402         int len;
 1403         int pdata;
 1404         const struct mbuf *m2;
 1405 
 1406         if (m->m_flags & M_PKTHDR)
 1407                 len = m->m_pkthdr.len;
 1408         else
 1409                 len = -1;
 1410         m2 = m;
 1411         while (m2 != NULL && (len == -1 || len)) {
 1412                 pdata = m2->m_len;
 1413                 if (maxlen != -1 && pdata > maxlen)
 1414                         pdata = maxlen;
 1415                 printf("mbuf: %p len: %d, next: %p, %b%s", m2, m2->m_len,
 1416                     m2->m_next, m2->m_flags, "\2\20freelist\17skipfw"
 1417                     "\11proto5\10proto4\7proto3\6proto2\5proto1\4rdonly"
 1418                     "\3eor\2pkthdr\1ext", pdata ? "" : "\n");
 1419                 if (pdata)
 1420                         printf(", %*D\n", pdata, (u_char *)m2->m_data, "-");
 1421                 if (len != -1)
 1422                         len -= m2->m_len;
 1423                 m2 = m2->m_next;
 1424         }
 1425         if (len > 0)
 1426                 printf("%d bytes unaccounted for.\n", len);
 1427         return;
 1428 }
 1429 
 1430 u_int
 1431 m_fixhdr(struct mbuf *m0)
 1432 {
 1433         u_int len;
 1434 
 1435         len = m_length(m0, NULL);
 1436         m0->m_pkthdr.len = len;
 1437         return (len);
 1438 }
 1439 
 1440 u_int
 1441 m_length(struct mbuf *m0, struct mbuf **last)
 1442 {
 1443         struct mbuf *m;
 1444         u_int len;
 1445 
 1446         len = 0;
 1447         for (m = m0; m != NULL; m = m->m_next) {
 1448                 len += m->m_len;
 1449                 if (m->m_next == NULL)
 1450                         break;
 1451         }
 1452         if (last != NULL)
 1453                 *last = m;
 1454         return (len);
 1455 }
 1456 
 1457 /*
 1458  * Defragment a mbuf chain, returning the shortest possible
 1459  * chain of mbufs and clusters.  If allocation fails and
 1460  * this cannot be completed, NULL will be returned, but
 1461  * the passed in chain will be unchanged.  Upon success,
 1462  * the original chain will be freed, and the new chain
 1463  * will be returned.
 1464  *
 1465  * If a non-packet header is passed in, the original
 1466  * mbuf (chain?) will be returned unharmed.
 1467  */
 1468 struct mbuf *
 1469 m_defrag(struct mbuf *m0, int how)
 1470 {
 1471         struct mbuf *m_new = NULL, *m_final = NULL;
 1472         int progress = 0, length;
 1473 
 1474         MBUF_CHECKSLEEP(how);
 1475         if (!(m0->m_flags & M_PKTHDR))
 1476                 return (m0);
 1477 
 1478         m_fixhdr(m0); /* Needed sanity check */
 1479 
 1480 #ifdef MBUF_STRESS_TEST
 1481         if (m_defragrandomfailures) {
 1482                 int temp = arc4random() & 0xff;
 1483                 if (temp == 0xba)
 1484                         goto nospace;
 1485         }
 1486 #endif
 1487         
 1488         if (m0->m_pkthdr.len > MHLEN)
 1489                 m_final = m_getcl(how, MT_DATA, M_PKTHDR);
 1490         else
 1491                 m_final = m_gethdr(how, MT_DATA);
 1492 
 1493         if (m_final == NULL)
 1494                 goto nospace;
 1495 
 1496         if (m_dup_pkthdr(m_final, m0, how) == 0)
 1497                 goto nospace;
 1498 
 1499         m_new = m_final;
 1500 
 1501         while (progress < m0->m_pkthdr.len) {
 1502                 length = m0->m_pkthdr.len - progress;
 1503                 if (length > MCLBYTES)
 1504                         length = MCLBYTES;
 1505 
 1506                 if (m_new == NULL) {
 1507                         if (length > MLEN)
 1508                                 m_new = m_getcl(how, MT_DATA, 0);
 1509                         else
 1510                                 m_new = m_get(how, MT_DATA);
 1511                         if (m_new == NULL)
 1512                                 goto nospace;
 1513                 }
 1514 
 1515                 m_copydata(m0, progress, length, mtod(m_new, caddr_t));
 1516                 progress += length;
 1517                 m_new->m_len = length;
 1518                 if (m_new != m_final)
 1519                         m_cat(m_final, m_new);
 1520                 m_new = NULL;
 1521         }
 1522 #ifdef MBUF_STRESS_TEST
 1523         if (m0->m_next == NULL)
 1524                 m_defraguseless++;
 1525 #endif
 1526         m_freem(m0);
 1527         m0 = m_final;
 1528 #ifdef MBUF_STRESS_TEST
 1529         m_defragpackets++;
 1530         m_defragbytes += m0->m_pkthdr.len;
 1531 #endif
 1532         return (m0);
 1533 nospace:
 1534 #ifdef MBUF_STRESS_TEST
 1535         m_defragfailure++;
 1536 #endif
 1537         if (m_final)
 1538                 m_freem(m_final);
 1539         return (NULL);
 1540 }
 1541 
 1542 #ifdef MBUF_STRESS_TEST
 1543 
 1544 /*
 1545  * Fragment an mbuf chain.  There's no reason you'd ever want to do
 1546  * this in normal usage, but it's great for stress testing various
 1547  * mbuf consumers.
 1548  *
 1549  * If fragmentation is not possible, the original chain will be
 1550  * returned.
 1551  *
 1552  * Possible length values:
 1553  * 0     no fragmentation will occur
 1554  * > 0  each fragment will be of the specified length
 1555  * -1   each fragment will be the same random value in length
 1556  * -2   each fragment's length will be entirely random
 1557  * (Random values range from 1 to 256)
 1558  */
 1559 struct mbuf *
 1560 m_fragment(struct mbuf *m0, int how, int length)
 1561 {
 1562         struct mbuf *m_new = NULL, *m_final = NULL;
 1563         int progress = 0;
 1564 
 1565         if (!(m0->m_flags & M_PKTHDR))
 1566                 return (m0);
 1567         
 1568         if ((length == 0) || (length < -2))
 1569                 return (m0);
 1570 
 1571         m_fixhdr(m0); /* Needed sanity check */
 1572 
 1573         m_final = m_getcl(how, MT_DATA, M_PKTHDR);
 1574 
 1575         if (m_final == NULL)
 1576                 goto nospace;
 1577 
 1578         if (m_dup_pkthdr(m_final, m0, how) == 0)
 1579                 goto nospace;
 1580 
 1581         m_new = m_final;
 1582 
 1583         if (length == -1)
 1584                 length = 1 + (arc4random() & 255);
 1585 
 1586         while (progress < m0->m_pkthdr.len) {
 1587                 int fraglen;
 1588 
 1589                 if (length > 0)
 1590                         fraglen = length;
 1591                 else
 1592                         fraglen = 1 + (arc4random() & 255);
 1593                 if (fraglen > m0->m_pkthdr.len - progress)
 1594                         fraglen = m0->m_pkthdr.len - progress;
 1595 
 1596                 if (fraglen > MCLBYTES)
 1597                         fraglen = MCLBYTES;
 1598 
 1599                 if (m_new == NULL) {
 1600                         m_new = m_getcl(how, MT_DATA, 0);
 1601                         if (m_new == NULL)
 1602                                 goto nospace;
 1603                 }
 1604 
 1605                 m_copydata(m0, progress, fraglen, mtod(m_new, caddr_t));
 1606                 progress += fraglen;
 1607                 m_new->m_len = fraglen;
 1608                 if (m_new != m_final)
 1609                         m_cat(m_final, m_new);
 1610                 m_new = NULL;
 1611         }
 1612         m_freem(m0);
 1613         m0 = m_final;
 1614         return (m0);
 1615 nospace:
 1616         if (m_final)
 1617                 m_freem(m_final);
 1618         /* Return the original chain on failure */
 1619         return (m0);
 1620 }
 1621 
 1622 #endif
 1623 
 1624 /*
 1625  * Copy the contents of uio into a properly sized mbuf chain.
 1626  */
 1627 struct mbuf *
 1628 m_uiotombuf(struct uio *uio, int how, int len, int align, int flags)
 1629 {
 1630         struct mbuf *m, *mb;
 1631         int error, length, total;
 1632         int progress = 0;
 1633 
 1634         /*
 1635          * len can be zero or an arbitrary large value bound by
 1636          * the total data supplied by the uio.
 1637          */
 1638         if (len > 0)
 1639                 total = min(uio->uio_resid, len);
 1640         else
 1641                 total = uio->uio_resid;
 1642 
 1643         /*
 1644          * The smallest unit returned by m_getm2() is a single mbuf
 1645          * with pkthdr.  We can't align past it.  Align align itself.
 1646          */
 1647         if (align)
 1648                 align &= ~(sizeof(long) - 1);
 1649         if (align >= MHLEN)
 1650                 return (NULL);
 1651 
 1652         /*
 1653          * Give us the full allocation or nothing.
 1654          * If len is zero return the smallest empty mbuf.
 1655          */
 1656         m = m_getm2(NULL, max(total + align, 1), how, MT_DATA, flags);
 1657         if (m == NULL)
 1658                 return (NULL);
 1659         m->m_data += align;
 1660 
 1661         /* Fill all mbufs with uio data and update header information. */
 1662         for (mb = m; mb != NULL; mb = mb->m_next) {
 1663                 length = min(M_TRAILINGSPACE(mb), total - progress);
 1664 
 1665                 error = uiomove(mtod(mb, void *), length, uio);
 1666                 if (error) {
 1667                         m_freem(m);
 1668                         return (NULL);
 1669                 }
 1670 
 1671                 mb->m_len = length;
 1672                 progress += length;
 1673                 if (flags & M_PKTHDR)
 1674                         m->m_pkthdr.len += length;
 1675         }
 1676         KASSERT(progress == total, ("%s: progress != total", __func__));
 1677 
 1678         return (m);
 1679 }
 1680 
 1681 /*
 1682  * Set the m_data pointer of a newly-allocated mbuf
 1683  * to place an object of the specified size at the
 1684  * end of the mbuf, longword aligned.
 1685  */
 1686 void
 1687 m_align(struct mbuf *m, int len)
 1688 {
 1689         int adjust;
 1690 
 1691         if (m->m_flags & M_EXT)
 1692                 adjust = m->m_ext.ext_size - len;
 1693         else if (m->m_flags & M_PKTHDR)
 1694                 adjust = MHLEN - len;
 1695         else
 1696                 adjust = MLEN - len;
 1697         m->m_data += adjust &~ (sizeof(long)-1);
 1698 }
 1699 
 1700 /*
 1701  * Create a writable copy of the mbuf chain.  While doing this
 1702  * we compact the chain with a goal of producing a chain with
 1703  * at most two mbufs.  The second mbuf in this chain is likely
 1704  * to be a cluster.  The primary purpose of this work is to create
 1705  * a writable packet for encryption, compression, etc.  The
 1706  * secondary goal is to linearize the data so the data can be
 1707  * passed to crypto hardware in the most efficient manner possible.
 1708  */
 1709 struct mbuf *
 1710 m_unshare(struct mbuf *m0, int how)
 1711 {
 1712         struct mbuf *m, *mprev;
 1713         struct mbuf *n, *mfirst, *mlast;
 1714         int len, off;
 1715 
 1716         mprev = NULL;
 1717         for (m = m0; m != NULL; m = mprev->m_next) {
 1718                 /*
 1719                  * Regular mbufs are ignored unless there's a cluster
 1720                  * in front of it that we can use to coalesce.  We do
 1721                  * the latter mainly so later clusters can be coalesced
 1722                  * also w/o having to handle them specially (i.e. convert
 1723                  * mbuf+cluster -> cluster).  This optimization is heavily
 1724                  * influenced by the assumption that we're running over
 1725                  * Ethernet where MCLBYTES is large enough that the max
 1726                  * packet size will permit lots of coalescing into a
 1727                  * single cluster.  This in turn permits efficient
 1728                  * crypto operations, especially when using hardware.
 1729                  */
 1730                 if ((m->m_flags & M_EXT) == 0) {
 1731                         if (mprev && (mprev->m_flags & M_EXT) &&
 1732                             m->m_len <= M_TRAILINGSPACE(mprev)) {
 1733                                 /* XXX: this ignores mbuf types */
 1734                                 memcpy(mtod(mprev, caddr_t) + mprev->m_len,
 1735                                        mtod(m, caddr_t), m->m_len);
 1736                                 mprev->m_len += m->m_len;
 1737                                 mprev->m_next = m->m_next;      /* unlink from chain */
 1738                                 m_free(m);                      /* reclaim mbuf */
 1739 #if 0
 1740                                 newipsecstat.ips_mbcoalesced++;
 1741 #endif
 1742                         } else {
 1743                                 mprev = m;
 1744                         }
 1745                         continue;
 1746                 }
 1747                 /*
 1748                  * Writable mbufs are left alone (for now).
 1749                  */
 1750                 if (M_WRITABLE(m)) {
 1751                         mprev = m;
 1752                         continue;
 1753                 }
 1754 
 1755                 /*
 1756                  * Not writable, replace with a copy or coalesce with
 1757                  * the previous mbuf if possible (since we have to copy
 1758                  * it anyway, we try to reduce the number of mbufs and
 1759                  * clusters so that future work is easier).
 1760                  */
 1761                 KASSERT(m->m_flags & M_EXT, ("m_flags 0x%x", m->m_flags));
 1762                 /* NB: we only coalesce into a cluster or larger */
 1763                 if (mprev != NULL && (mprev->m_flags & M_EXT) &&
 1764                     m->m_len <= M_TRAILINGSPACE(mprev)) {
 1765                         /* XXX: this ignores mbuf types */
 1766                         memcpy(mtod(mprev, caddr_t) + mprev->m_len,
 1767                                mtod(m, caddr_t), m->m_len);
 1768                         mprev->m_len += m->m_len;
 1769                         mprev->m_next = m->m_next;      /* unlink from chain */
 1770                         m_free(m);                      /* reclaim mbuf */
 1771 #if 0
 1772                         newipsecstat.ips_clcoalesced++;
 1773 #endif
 1774                         continue;
 1775                 }
 1776 
 1777                 /*
 1778                  * Allocate new space to hold the copy...
 1779                  */
 1780                 /* XXX why can M_PKTHDR be set past the first mbuf? */
 1781                 if (mprev == NULL && (m->m_flags & M_PKTHDR)) {
 1782                         /*
 1783                          * NB: if a packet header is present we must
 1784                          * allocate the mbuf separately from any cluster
 1785                          * because M_MOVE_PKTHDR will smash the data
 1786                          * pointer and drop the M_EXT marker.
 1787                          */
 1788                         MGETHDR(n, how, m->m_type);
 1789                         if (n == NULL) {
 1790                                 m_freem(m0);
 1791                                 return (NULL);
 1792                         }
 1793                         M_MOVE_PKTHDR(n, m);
 1794                         MCLGET(n, how);
 1795                         if ((n->m_flags & M_EXT) == 0) {
 1796                                 m_free(n);
 1797                                 m_freem(m0);
 1798                                 return (NULL);
 1799                         }
 1800                 } else {
 1801                         n = m_getcl(how, m->m_type, m->m_flags);
 1802                         if (n == NULL) {
 1803                                 m_freem(m0);
 1804                                 return (NULL);
 1805                         }
 1806                 }
 1807                 /*
 1808                  * ... and copy the data.  We deal with jumbo mbufs
 1809                  * (i.e. m_len > MCLBYTES) by splitting them into
 1810                  * clusters.  We could just malloc a buffer and make
 1811                  * it external but too many device drivers don't know
 1812                  * how to break up the non-contiguous memory when
 1813                  * doing DMA.
 1814                  */
 1815                 len = m->m_len;
 1816                 off = 0;
 1817                 mfirst = n;
 1818                 mlast = NULL;
 1819                 for (;;) {
 1820                         int cc = min(len, MCLBYTES);
 1821                         memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc);
 1822                         n->m_len = cc;
 1823                         if (mlast != NULL)
 1824                                 mlast->m_next = n;
 1825                         mlast = n;      
 1826 #if 0
 1827                         newipsecstat.ips_clcopied++;
 1828 #endif
 1829 
 1830                         len -= cc;
 1831                         if (len <= 0)
 1832                                 break;
 1833                         off += cc;
 1834 
 1835                         n = m_getcl(how, m->m_type, m->m_flags);
 1836                         if (n == NULL) {
 1837                                 m_freem(mfirst);
 1838                                 m_freem(m0);
 1839                                 return (NULL);
 1840                         }
 1841                 }
 1842                 n->m_next = m->m_next; 
 1843                 if (mprev == NULL)
 1844                         m0 = mfirst;            /* new head of chain */
 1845                 else
 1846                         mprev->m_next = mfirst; /* replace old mbuf */
 1847                 m_free(m);                      /* release old mbuf */
 1848                 mprev = mfirst;
 1849         }
 1850         return (m0);
 1851 }

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