sys/kern/uipc_mbuf2.c

   1 /*      $FreeBSD: src/sys/kern/uipc_mbuf2.c,v 1.2.2.5 2003/01/23 21:06:44 sam Exp $     */
   2 /*      $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $     */
   3 /*      $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $   */
   4
   5 /*
   6  * Copyright (C) 1999 WIDE Project.
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the project nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 /*
  35  * Copyright (c) 1982, 1986, 1988, 1991, 1993
  36  *      The Regents of the University of California.  All rights reserved.
  37  *
  38  * Redistribution and use in source and binary forms, with or without
  39  * modification, are permitted provided that the following conditions
  40  * are met:
  41  * 1. Redistributions of source code must retain the above copyright
  42  *    notice, this list of conditions and the following disclaimer.
  43  * 2. Redistributions in binary form must reproduce the above copyright
  44  *    notice, this list of conditions and the following disclaimer in the
  45  *    documentation and/or other materials provided with the distribution.
  46  * 3. Neither the name of the University nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  51  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  53  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  54  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  58  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  59  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  60  * SUCH DAMAGE.
  61  *
  62  *      @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
  63  */
  64
  65 /*#define PULLDOWN_DEBUG*/
  66
  67 #include <sys/param.h>
  68 #include <sys/systm.h>
  69 #include <sys/kernel.h>
  70 #include <sys/proc.h>
  71 #include <sys/malloc.h>
  72 #include <sys/mbuf.h>
  73
  74 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information");
  75
  76 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
  77 static struct mbuf *m_dup1 (struct mbuf *, int, int, int);
  78
  79 /*
  80  * ensure that [off, off + len) is contiguous on the mbuf chain "m".
  81  * packet chain before "off" is kept untouched.
  82  * if offp == NULL, the target will start at <retval, 0> on resulting chain.
  83  * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
  84  *
  85  * on error return (NULL return value), original "m" will be freed.
  86  *
  87  * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
  88  */
  89 struct mbuf *
  90 m_pulldown(struct mbuf *m, int off, int len, int *offp)
  91 {
  92         struct mbuf *n, *o;
  93         int hlen, tlen, olen;
  94         int sharedcluster;
  95
  96         /* check invalid arguments. */
  97         if (m == NULL)
  98                 panic("m == NULL in m_pulldown()");
  99         if (len > MCLBYTES) {
 100                 m_freem(m);
 101                 return NULL;    /* impossible */
 102         }
 103
 104 #ifdef PULLDOWN_DEBUG
 105     {
 106         struct mbuf *t;
 107         kprintf("before:");
 108         for (t = m; t; t = t->m_next)
 109                 kprintf(" %d", t->m_len);
 110         kprintf("\n");
 111     }
 112 #endif
 113         n = m;
 114         while (n != NULL && off > 0) {
 115                 if (n->m_len > off)
 116                         break;
 117                 off -= n->m_len;
 118                 n = n->m_next;
 119         }
 120         /* be sure to point non-empty mbuf */
 121         while (n != NULL && n->m_len == 0)
 122                 n = n->m_next;
 123         if (!n) {
 124                 m_freem(m);
 125                 return NULL;    /* mbuf chain too short */
 126         }
 127
 128         sharedcluster = (m_sharecount(n) > 1);
 129
 130         /*
 131          * the target data is on <n, off>.
 132          * if we got enough data on the mbuf "n", we're done.
 133          */
 134         if ((off == 0 || offp) && len <= n->m_len - off && !sharedcluster)
 135                 goto ok;
 136
 137         /*
 138          * when len <= n->m_len - off and off != 0, it is a special case.
 139          * len bytes from <n, off> sits in single mbuf, but the caller does
 140          * not like the starting position (off).
 141          * chop the current mbuf into two pieces, set off to 0.
 142          */
 143         if (len <= n->m_len - off) {
 144                 o = m_dup1(n, off, n->m_len - off, M_NOWAIT);
 145                 if (o == NULL) {
 146                         m_freem(m);
 147                         return NULL;    /* ENOBUFS */
 148                 }
 149                 n->m_len = off;
 150                 o->m_next = n->m_next;
 151                 n->m_next = o;
 152                 n = n->m_next;
 153                 off = 0;
 154                 goto ok;
 155         }
 156
 157         /*
 158          * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
 159          * and construct contiguous mbuf with m_len == len.
 160          * note that hlen + tlen == len, and tlen > 0.
 161          */
 162         hlen = n->m_len - off;
 163         tlen = len - hlen;
 164
 165         /*
 166          * ensure that we have enough trailing data on mbuf chain.
 167          * if not, we can do nothing about the chain.
 168          */
 169         olen = 0;
 170         for (o = n->m_next; o != NULL; o = o->m_next)
 171                 olen += o->m_len;
 172         if (hlen + olen < len) {
 173                 m_freem(m);
 174                 return NULL;    /* mbuf chain too short */
 175         }
 176
 177         /*
 178          * easy cases first.
 179          * we need to use m_copydata() to get data from <n->m_next, 0>.
 180          */
 181         if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
 182             !sharedcluster) {
 183                 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
 184                 n->m_len += tlen;
 185                 m_adj(n->m_next, tlen);
 186                 goto ok;
 187         }
 188         if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
 189             !sharedcluster) {
 190                 n->m_next->m_data -= hlen;
 191                 n->m_next->m_len += hlen;
 192                 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
 193                 n->m_len -= hlen;
 194                 n = n->m_next;
 195                 off = 0;
 196                 goto ok;
 197         }
 198
 199         /*
 200          * now, we need to do the hard way.  don't m_copy as there's no room
 201          * on both end.
 202          */
 203         o = m_getl(len, M_NOWAIT, m->m_type, 0, NULL);
 204         if (!o) {
 205                 m_freem(m);
 206                 return NULL;    /* ENOBUFS */
 207         }
 208         /* get hlen from <n, off> into <o, 0> */
 209         o->m_len = hlen;
 210         bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
 211         n->m_len -= hlen;
 212         /* get tlen from <n->m_next, 0> into <o, hlen> */
 213         m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
 214         o->m_len += tlen;
 215         m_adj(n->m_next, tlen);
 216         o->m_next = n->m_next;
 217         n->m_next = o;
 218         n = o;
 219         off = 0;
 220
 221 ok:
 222 #ifdef PULLDOWN_DEBUG
 223     {
 224         struct mbuf *t;
 225         kprintf("after:");
 226         for (t = m; t; t = t->m_next)
 227                 kprintf("%c%d", t == n ? '*' : ' ', t->m_len);
 228         kprintf(" (off=%d)\n", off);
 229     }
 230 #endif
 231         if (offp)
 232                 *offp = off;
 233         return n;
 234 }
 235
 236 static struct mbuf *
 237 m_dup1(struct mbuf *m, int off, int len, int wait)
 238 {
 239         struct mbuf *n;
 240
 241         if (len > MCLBYTES)
 242                 return NULL;
 243         n = m_getl(len, wait, m->m_type, m->m_flags, NULL);
 244         if (!n)
 245                 return NULL;
 246         if (off == 0 && (m->m_flags & M_PKTHDR) && !m_dup_pkthdr(n, m, wait)) {
 247                 m_free(n);
 248                 return NULL;
 249         }
 250         m_copydata(m, off, len, mtod(n, caddr_t));
 251         return n;
 252 }
 253
 254 /* Get a packet tag structure along with specified data following. */
 255 struct m_tag *
 256 m_tag_alloc(uint32_t cookie, int type, int len, int mflags)
 257 {
 258         struct m_tag *t;
 259
 260         if (len < 0)
 261                 return NULL;
 262         t = kmalloc(len + sizeof(struct m_tag), M_PACKET_TAGS, mflags);
 263         if (t == NULL)
 264                 return NULL;
 265         t->m_tag_id = type;
 266         t->m_tag_len = len;
 267         t->m_tag_cookie = cookie;
 268         return t;
 269 }
 270
 271
 272 /* Free a packet tag. */
 273 void
 274 m_tag_free(struct m_tag *t)
 275 {
 276         kfree(t, M_PACKET_TAGS);
 277 }
 278
 279 /* Prepend a packet tag. */
 280 void
 281 m_tag_prepend(struct mbuf *m, struct m_tag *t)
 282 {
 283         KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t));
 284         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_prepend: mbuf %p non-header", m));
 285         SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
 286 }
 287
 288 /* Unlink a packet tag. */
 289 void
 290 m_tag_unlink(struct mbuf *m, struct m_tag *t)
 291 {
 292         KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t));
 293         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_unlink: mbuf %p non-header", m));
 294         SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
 295 }
 296
 297 /* Unlink and free a packet tag. */
 298 void
 299 m_tag_delete(struct mbuf *m, struct m_tag *t)
 300 {
 301         KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
 302         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete: mbuf %p non-header", m));
 303         m_tag_unlink(m, t);
 304         m_tag_free(t);
 305 }
 306
 307 /* Unlink and free a packet tag chain, starting from given tag. */
 308 void
 309 m_tag_delete_chain(struct mbuf *m)
 310 {
 311         struct m_tag *p, *q;
 312
 313         KASSERT(m, ("m_tag_delete_chain: null mbuf"));
 314         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete_chain: mbuf %p non-header", m));
 315         p = SLIST_FIRST(&m->m_pkthdr.tags);
 316         if (p == NULL)
 317                 return;
 318         while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
 319                 m_tag_delete(m, q);
 320         m_tag_delete(m, p);
 321 }
 322
 323 /* Find a tag, starting from a given position. */
 324 struct m_tag *
 325 m_tag_locate(struct mbuf *m, uint32_t cookie, int type, struct m_tag *t)
 326 {
 327         struct m_tag *p;
 328
 329         KASSERT(m, ("m_tag_find: null mbuf"));
 330         if (t == NULL)
 331                 p = SLIST_FIRST(&m->m_pkthdr.tags);
 332         else
 333                 p = SLIST_NEXT(t, m_tag_link);
 334         while (p != NULL) {
 335                 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
 336                         return p;
 337                 p = SLIST_NEXT(p, m_tag_link);
 338         }
 339         return NULL;
 340 }
 341
 342 /* Copy a single tag. */
 343 struct m_tag *
 344 m_tag_copy(struct m_tag *t, int how)
 345 {
 346         struct m_tag *p;
 347
 348         KASSERT(t, ("m_tag_copy: null tag"));
 349         p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
 350         if (p == NULL)
 351                 return (NULL);
 352         bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
 353         return p;
 354 }
 355
 356 /*
 357  * Copy two tag chains. The destination mbuf (to) loses any attached
 358  * tags even if the operation fails. This should not be a problem, as
 359  * m_tag_copy_chain() is typically called with a newly-allocated
 360  * destination mbuf.
 361  */
 362 int
 363 m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how)
 364 {
 365         struct m_tag *p, *t, *tprev = NULL;
 366
 367         KASSERT(to && from,
 368                 ("m_tag_copy: null argument, to %p from %p", to, from));
 369         m_tag_delete_chain(to);
 370         SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
 371                 t = m_tag_copy(p, how);
 372                 if (t == NULL) {
 373                         m_tag_delete_chain(to);
 374                         return 0;
 375                 }
 376                 if (tprev == NULL)
 377                         SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
 378                 else {
 379                         SLIST_INSERT_AFTER(tprev, t, m_tag_link);
 380                         tprev = t;
 381                 }
 382         }
 383         return 1;
 384 }
 385
 386 /* Initialize tags on an mbuf. */
 387 void
 388 m_tag_init(struct mbuf *m)
 389 {
 390         SLIST_INIT(&m->m_pkthdr.tags);
 391 }
 392
 393 /* Get first tag in chain. */
 394 struct m_tag *
 395 m_tag_first(struct mbuf *m)
 396 {
 397         return SLIST_FIRST(&m->m_pkthdr.tags);
 398 }
 399
 400 /* Get next tag in chain. */
 401 struct m_tag *
 402 m_tag_next(struct mbuf *m, struct m_tag *t)
 403 {
 404         return SLIST_NEXT(t, m_tag_link);
 405 }