FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf2.c

     /*      $NetBSD: uipc_mbuf2.c,v 1.25 2006/11/01 10:17:59 yamt Exp $     */
     /*      $KAME: uipc_mbuf2.c,v 1.29 2001/02/14 13:42:10 itojun Exp $     */
     
     /*
      * Copyright (C) 1999 WIDE Project.
      * 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 project 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 PROJECT 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 PROJECT OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    /*
     * Copyright (c) 1982, 1986, 1988, 1991, 1993
     *      The Regents of the University of California.  All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: uipc_mbuf2.c,v 1.25 2006/11/01 10:17:59 yamt Exp $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    
    MALLOC_DEFINE(M_PACKET_TAGS, "packet tags", "Packet-attached information");
    
    /*
     * ensure that [off, off + len) is contiguous on the mbuf chain "m".
     * packet chain before "off" is kept untouched.
     * if offp == NULL, the target will start at <retval, 0> on resulting chain.
     * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
     *
     * on error return (NULL return value), original "m" will be freed.
     *
     * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
     */
    struct mbuf *
    m_pulldown(struct mbuf *m, int off, int len, int *offp)
    {
            struct mbuf *n, *o;
            int hlen, tlen, olen;
            int sharedcluster;
    
            /* check invalid arguments. */
            if (m == NULL)
                    panic("m == NULL in m_pulldown()");
            if (len > MCLBYTES) {
                    m_freem(m);
                    return NULL;    /* impossible */
            }
    
           n = m;
           while (n != NULL && off > 0) {
                   if (n->m_len > off)
                           break;
                   off -= n->m_len;
                   n = n->m_next;
           }
           /* be sure to point non-empty mbuf */
           while (n != NULL && n->m_len == 0)
                   n = n->m_next;
           if (!n) {
                   m_freem(m);
                   return NULL;    /* mbuf chain too short */
           }
   
           sharedcluster = M_READONLY(n);
   
           /*
            * the target data is on <n, off>.
            * if we got enough data on the mbuf "n", we're done.
            */
           if ((off == 0 || offp) && len <= n->m_len - off && !sharedcluster)
                   goto ok;
   
           /*
            * when len <= n->m_len - off and off != 0, it is a special case.
            * len bytes from <n, off> sits in single mbuf, but the caller does
            * not like the starting position (off).
            * chop the current mbuf into two pieces, set off to 0.
            */
           if (len <= n->m_len - off) {
                   struct mbuf *mlast;
   
                   o = m_dup(n, off, n->m_len - off, M_DONTWAIT);
                   if (o == NULL) {
                           m_freem(m);
                           return NULL;    /* ENOBUFS */
                   }
                   KASSERT(o->m_len >= len);
                   for (mlast = o; mlast->m_next != NULL; mlast = mlast->m_next)
                           ;
                   n->m_len = off;
                   mlast->m_next = n->m_next;
                   n->m_next = o;
                   n = o;
                   off = 0;
                   goto ok;
           }
   
           /*
            * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
            * and construct contiguous mbuf with m_len == len.
            * note that hlen + tlen == len, and tlen > 0.
            */
           hlen = n->m_len - off;
           tlen = len - hlen;
   
           /*
            * ensure that we have enough trailing data on mbuf chain.
            * if not, we can do nothing about the chain.
            */
           olen = 0;
           for (o = n->m_next; o != NULL; o = o->m_next)
                   olen += o->m_len;
           if (hlen + olen < len) {
                   m_freem(m);
                   return NULL;    /* mbuf chain too short */
           }
   
           /*
            * easy cases first.
            * we need to use m_copydata() to get data from <n->m_next, 0>.
            */
           if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
               !sharedcluster) {
                   m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
                   n->m_len += tlen;
                   m_adj(n->m_next, tlen);
                   goto ok;
           }
           if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
               !sharedcluster && n->m_next->m_len >= tlen) {
                   n->m_next->m_data -= hlen;
                   n->m_next->m_len += hlen;
                   memcpy(mtod(n->m_next, caddr_t), mtod(n, caddr_t) + off, hlen);
                   n->m_len -= hlen;
                   n = n->m_next;
                   off = 0;
                   goto ok;
           }
   
           /*
            * now, we need to do the hard way.  don't m_copy as there's no room
            * on both end.
            */
           MGET(o, M_DONTWAIT, m->m_type);
           if (o && len > MLEN) {
                   MCLGET(o, M_DONTWAIT);
                   if ((o->m_flags & M_EXT) == 0) {
                           m_free(o);
                           o = NULL;
                   }
           }
           if (!o) {
                   m_freem(m);
                   return NULL;    /* ENOBUFS */
           }
           /* get hlen from <n, off> into <o, 0> */
           o->m_len = hlen;
           memcpy(mtod(o, caddr_t), mtod(n, caddr_t) + off, hlen);
           n->m_len -= hlen;
           /* get tlen from <n->m_next, 0> into <o, hlen> */
           m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
           o->m_len += tlen;
           m_adj(n->m_next, tlen);
           o->m_next = n->m_next;
           n->m_next = o;
           n = o;
           off = 0;
   
   ok:
           if (offp)
                   *offp = off;
           return n;
   }
   
   /*
    * FreeBSD 4.6 introduced m_getcl(), which performs `fast' allocation
    * mbuf clusters from a cache of recently-freed clusters. (If the cache
    * is empty, new clusters are allocated en-masse).
    * On NetBSD, for now, implement the `cache' as a function
    * using normal NetBSD mbuf/cluster allocation macros. Replace this
    * with fast-cache code, if and when NetBSD implements one.
    */
   struct mbuf *
   m_getcl(int how, int type, int flags)
   {
           struct mbuf *mp;
   
           if ((flags & M_PKTHDR) != 0)
                   MGETHDR(mp, how, type);
           else
                   MGET(mp, how, type);
   
           if (mp == NULL)
                   return NULL;
   
           MCLGET(mp, how);
           if ((mp->m_flags & M_EXT) != 0)
                   return mp;
   
           m_free(mp);
           return NULL;
   }
   
   /* Get a packet tag structure along with specified data following. */
   struct m_tag *
   m_tag_get(int type, int len, int wait)
   {
           struct m_tag *t;
   
           if (len < 0)
                   return (NULL);
           t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
           if (t == NULL)
                   return (NULL);
           t->m_tag_id = type;
           t->m_tag_len = len;
           return (t);
   }
   
   /* Free a packet tag. */
   void
   m_tag_free(struct m_tag *t)
   {
   
           free(t, M_PACKET_TAGS);
   }
   
   /* Prepend a packet tag. */
   void
   m_tag_prepend(struct mbuf *m, struct m_tag *t)
   {
   
           SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
   }
   
   /* Unlink a packet tag. */
   void
   m_tag_unlink(struct mbuf *m, struct m_tag *t)
   {
   
           SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
   }
   
   /* Unlink and free a packet tag. */
   void
   m_tag_delete(struct mbuf *m, struct m_tag *t)
   {
   
           m_tag_unlink(m, t);
           m_tag_free(t);
   }
   
   /* Unlink and free a packet tag chain, starting from given tag. */
   void
   m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
   {
           struct m_tag *p, *q;
   
           if (t != NULL)
                   p = t;
           else
                   p = SLIST_FIRST(&m->m_pkthdr.tags);
           if (p == NULL)
                   return;
           while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
                   m_tag_delete(m, q);
           m_tag_delete(m, p);
   }
   
   /*
    * Strip off all tags that would normally vanish when
    * passing through a network interface.  Only persistent
    * tags will exist after this; these are expected to remain
    * so long as the mbuf chain exists, regardless of the
    * path the mbufs take.
    */
   void
   m_tag_delete_nonpersistent(struct mbuf *m)
   {
           /* NetBSD has no persistent tags yet, so just delete all tags. */
           m_tag_delete_chain(m, NULL);
   }
   
   
   /* Find a tag, starting from a given position. */
   struct m_tag *
   m_tag_find(struct mbuf *m, int type, struct m_tag *t)
   {
           struct m_tag *p;
   
           if (t == NULL)
                   p = SLIST_FIRST(&m->m_pkthdr.tags);
           else
                   p = SLIST_NEXT(t, m_tag_link);
           while (p != NULL) {
                   if (p->m_tag_id == type)
                           return (p);
                   p = SLIST_NEXT(p, m_tag_link);
           }
           return (NULL);
   }
   
   /* Copy a single tag. */
   struct m_tag *
   m_tag_copy(struct m_tag *t)
   {
           struct m_tag *p;
   
           p = m_tag_get(t->m_tag_id, t->m_tag_len, M_NOWAIT);
           if (p == NULL)
                   return (NULL);
           bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
           return (p);
   }
   
   /*
    * Copy two tag chains. The destination mbuf (to) loses any attached
    * tags even if the operation fails. This should not be a problem, as
    * m_tag_copy_chain() is typically called with a newly-allocated
    * destination mbuf.
    */
   int
   m_tag_copy_chain(struct mbuf *to, struct mbuf *from)
   {
           struct m_tag *p, *t, *tprev = NULL;
   
           m_tag_delete_chain(to, NULL);
           SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
                   t = m_tag_copy(p);
                   if (t == NULL) {
                           m_tag_delete_chain(to, NULL);
                           return (0);
                   }
                   if (tprev == NULL)
                           SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
                   else
                           SLIST_INSERT_AFTER(tprev, t, m_tag_link);
                   tprev = t;
           }
           return (1);
   }
   
   /* Initialize tags on an mbuf. */
   void
   m_tag_init(struct mbuf *m)
   {
   
           SLIST_INIT(&m->m_pkthdr.tags);
   }
   
   /* Get first tag in chain. */
   struct m_tag *
   m_tag_first(struct mbuf *m)
   {
   
           return (SLIST_FIRST(&m->m_pkthdr.tags));
   }
   
   /* Get next tag in chain. */
   struct m_tag *
   m_tag_next(struct mbuf *m, struct m_tag *t)
   {
   
           return (SLIST_NEXT(t, m_tag_link));
   }

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