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 /*      $DragonFly: src/sys/kern/uipc_mbuf2.c,v 1.15 2007/10/20 10:28:44 sephe Exp $    */
   3 /*      $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $     */
   4 /*      $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $   */
   5
   6 /*
   7  * Copyright (C) 1999 WIDE Project.
   8  * All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the project nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 /*
  36  * Copyright (c) 1982, 1986, 1988, 1991, 1993
  37  *      The Regents of the University of California.  All rights reserved.
  38  *
  39  * Redistribution and use in source and binary forms, with or without
  40  * modification, are permitted provided that the following conditions
  41  * are met:
  42  * 1. Redistributions of source code must retain the above copyright
  43  *    notice, this list of conditions and the following disclaimer.
  44  * 2. Redistributions in binary form must reproduce the above copyright
  45  *    notice, this list of conditions and the following disclaimer in the
  46  *    documentation and/or other materials provided with the distribution.
  47  * 3. All advertising materials mentioning features or use of this software
  48  *    must display the following acknowledgement:
  49  *      This product includes software developed by the University of
  50  *      California, Berkeley and its contributors.
  51  * 4. Neither the name of the University nor the names of its contributors
  52  *    may be used to endorse or promote products derived from this software
  53  *    without specific prior written permission.
  54  *
  55  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  56  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  57  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  58  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  59  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  60  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  61  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  62  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  63  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  64  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  65  * SUCH DAMAGE.
  66  *
  67  *      @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
  68  */
  69
  70 /*#define PULLDOWN_DEBUG*/
  71
  72 #include <sys/param.h>
  73 #include <sys/systm.h>
  74 #include <sys/kernel.h>
  75 #include <sys/proc.h>
  76 #include <sys/malloc.h>
  77 #include <sys/mbuf.h>
  78
  79 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information");
  80
  81 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
  82 static struct mbuf *m_dup1 (struct mbuf *, int, int, int);
  83
  84 /*
  85  * ensure that [off, off + len) is contiguous on the mbuf chain "m".
  86  * packet chain before "off" is kept untouched.
  87  * if offp == NULL, the target will start at <retval, 0> on resulting chain.
  88  * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
  89  *
  90  * on error return (NULL return value), original "m" will be freed.
  91  *
  92  * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
  93  */
  94 struct mbuf *
  95 m_pulldown(struct mbuf *m, int off, int len, int *offp)
  96 {
  97         struct mbuf *n, *o;
  98         int hlen, tlen, olen;
  99         int sharedcluster;
 100
 101         /* check invalid arguments. */
 102         if (m == NULL)
 103                 panic("m == NULL in m_pulldown()");
 104         if (len > MCLBYTES) {
 105                 m_freem(m);
 106                 return NULL;    /* impossible */
 107         }
 108
 109 #ifdef PULLDOWN_DEBUG
 110     {
 111         struct mbuf *t;
 112         kprintf("before:");
 113         for (t = m; t; t = t->m_next)
 114                 kprintf(" %d", t->m_len);
 115         kprintf("\n");
 116     }
 117 #endif
 118         n = m;
 119         while (n != NULL && off > 0) {
 120                 if (n->m_len > off)
 121                         break;
 122                 off -= n->m_len;
 123                 n = n->m_next;
 124         }
 125         /* be sure to point non-empty mbuf */
 126         while (n != NULL && n->m_len == 0)
 127                 n = n->m_next;
 128         if (!n) {
 129                 m_freem(m);
 130                 return NULL;    /* mbuf chain too short */
 131         }
 132
 133         sharedcluster = (m_sharecount(n) > 1);
 134
 135         /*
 136          * the target data is on <n, off>.
 137          * if we got enough data on the mbuf "n", we're done.
 138          */
 139         if ((off == 0 || offp) && len <= n->m_len - off && !sharedcluster)
 140                 goto ok;
 141
 142         /*
 143          * when len <= n->m_len - off and off != 0, it is a special case.
 144          * len bytes from <n, off> sits in single mbuf, but the caller does
 145          * not like the starting position (off).
 146          * chop the current mbuf into two pieces, set off to 0.
 147          */
 148         if (len <= n->m_len - off) {
 149                 o = m_dup1(n, off, n->m_len - off, MB_DONTWAIT);
 150                 if (o == NULL) {
 151                         m_freem(m);
 152                         return NULL;    /* ENOBUFS */
 153                 }
 154                 n->m_len = off;
 155                 o->m_next = n->m_next;
 156                 n->m_next = o;
 157                 n = n->m_next;
 158                 off = 0;
 159                 goto ok;
 160         }
 161
 162         /*
 163          * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
 164          * and construct contiguous mbuf with m_len == len.
 165          * note that hlen + tlen == len, and tlen > 0.
 166          */
 167         hlen = n->m_len - off;
 168         tlen = len - hlen;
 169
 170         /*
 171          * ensure that we have enough trailing data on mbuf chain.
 172          * if not, we can do nothing about the chain.
 173          */
 174         olen = 0;
 175         for (o = n->m_next; o != NULL; o = o->m_next)
 176                 olen += o->m_len;
 177         if (hlen + olen < len) {
 178                 m_freem(m);
 179                 return NULL;    /* mbuf chain too short */
 180         }
 181
 182         /*
 183          * easy cases first.
 184          * we need to use m_copydata() to get data from <n->m_next, 0>.
 185          */
 186         if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
 187             !sharedcluster) {
 188                 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
 189                 n->m_len += tlen;
 190                 m_adj(n->m_next, tlen);
 191                 goto ok;
 192         }
 193         if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
 194             !sharedcluster) {
 195                 n->m_next->m_data -= hlen;
 196                 n->m_next->m_len += hlen;
 197                 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
 198                 n->m_len -= hlen;
 199                 n = n->m_next;
 200                 off = 0;
 201                 goto ok;
 202         }
 203
 204         /*
 205          * now, we need to do the hard way.  don't m_copy as there's no room
 206          * on both end.
 207          */
 208         o = m_getl(len, MB_DONTWAIT, m->m_type, 0, NULL);
 209         if (!o) {
 210                 m_freem(m);
 211                 return NULL;    /* ENOBUFS */
 212         }
 213         /* get hlen from <n, off> into <o, 0> */
 214         o->m_len = hlen;
 215         bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
 216         n->m_len -= hlen;
 217         /* get tlen from <n->m_next, 0> into <o, hlen> */
 218         m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
 219         o->m_len += tlen;
 220         m_adj(n->m_next, tlen);
 221         o->m_next = n->m_next;
 222         n->m_next = o;
 223         n = o;
 224         off = 0;
 225
 226 ok:
 227 #ifdef PULLDOWN_DEBUG
 228     {
 229         struct mbuf *t;
 230         kprintf("after:");
 231         for (t = m; t; t = t->m_next)
 232                 kprintf("%c%d", t == n ? '*' : ' ', t->m_len);
 233         kprintf(" (off=%d)\n", off);
 234     }
 235 #endif
 236         if (offp)
 237                 *offp = off;
 238         return n;
 239 }
 240
 241 static struct mbuf *
 242 m_dup1(struct mbuf *m, int off, int len, int wait)
 243 {
 244         struct mbuf *n;
 245
 246         if (len > MCLBYTES)
 247                 return NULL;
 248         n = m_getl(len, wait, m->m_type, m->m_flags, NULL);
 249         if (!n)
 250                 return NULL;
 251         if (off == 0 && (m->m_flags & M_PKTHDR) && !m_dup_pkthdr(n, m, wait)) {
 252                 m_free(n);
 253                 return NULL;
 254         }
 255         m_copydata(m, off, len, mtod(n, caddr_t));
 256         return n;
 257 }
 258
 259 /* Get a packet tag structure along with specified data following. */
 260 struct m_tag *
 261 m_tag_alloc(u_int32_t cookie, int type, int len, int wait)
 262 {
 263         struct m_tag *t;
 264
 265         if (len < 0)
 266                 return NULL;
 267         t = kmalloc(len + sizeof(struct m_tag), M_PACKET_TAGS, MBTOM(wait));
 268         if (t == NULL)
 269                 return NULL;
 270         t->m_tag_id = type;
 271         t->m_tag_len = len;
 272         t->m_tag_cookie = cookie;
 273         return t;
 274 }
 275
 276
 277 /* Free a packet tag. */
 278 void
 279 m_tag_free(struct m_tag *t)
 280 {
 281         kfree(t, M_PACKET_TAGS);
 282 }
 283
 284 /* Prepend a packet tag. */
 285 void
 286 m_tag_prepend(struct mbuf *m, struct m_tag *t)
 287 {
 288         KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t));
 289         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_prepend: mbuf %p non-header", m));
 290         SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
 291 }
 292
 293 /* Unlink a packet tag. */
 294 void
 295 m_tag_unlink(struct mbuf *m, struct m_tag *t)
 296 {
 297         KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t));
 298         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_unlink: mbuf %p non-header", m));
 299         SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
 300 }
 301
 302 /* Unlink and free a packet tag. */
 303 void
 304 m_tag_delete(struct mbuf *m, struct m_tag *t)
 305 {
 306         KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
 307         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete: mbuf %p non-header", m));
 308         m_tag_unlink(m, t);
 309         m_tag_free(t);
 310 }
 311
 312 /* Unlink and free a packet tag chain, starting from given tag. */
 313 void
 314 m_tag_delete_chain(struct mbuf *m)
 315 {
 316         struct m_tag *p, *q;
 317
 318         KASSERT(m, ("m_tag_delete_chain: null mbuf"));
 319         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete_chain: mbuf %p non-header", m));
 320         p = SLIST_FIRST(&m->m_pkthdr.tags);
 321         if (p == NULL)
 322                 return;
 323         while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
 324                 m_tag_delete(m, q);
 325         m_tag_delete(m, p);
 326 }
 327
 328 /* Find a tag, starting from a given position. */
 329 struct m_tag *
 330 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t)
 331 {
 332         struct m_tag *p;
 333
 334         KASSERT(m, ("m_tag_find: null mbuf"));
 335         if (t == NULL)
 336                 p = SLIST_FIRST(&m->m_pkthdr.tags);
 337         else
 338                 p = SLIST_NEXT(t, m_tag_link);
 339         while (p != NULL) {
 340                 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
 341                         return p;
 342                 p = SLIST_NEXT(p, m_tag_link);
 343         }
 344         return NULL;
 345 }
 346
 347 /* Copy a single tag. */
 348 struct m_tag *
 349 m_tag_copy(struct m_tag *t, int how)
 350 {
 351         struct m_tag *p;
 352
 353         KASSERT(t, ("m_tag_copy: null tag"));
 354         p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
 355         if (p == NULL)
 356                 return (NULL);
 357         bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
 358         return p;
 359 }
 360
 361 /*
 362  * Copy two tag chains. The destination mbuf (to) loses any attached
 363  * tags even if the operation fails. This should not be a problem, as
 364  * m_tag_copy_chain() is typically called with a newly-allocated
 365  * destination mbuf.
 366  */
 367 int
 368 m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how)
 369 {
 370         struct m_tag *p, *t, *tprev = NULL;
 371
 372         KASSERT(to && from,
 373                 ("m_tag_copy: null argument, to %p from %p", to, from));
 374         m_tag_delete_chain(to);
 375         SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
 376                 t = m_tag_copy(p, how);
 377                 if (t == NULL) {
 378                         m_tag_delete_chain(to);
 379                         return 0;
 380                 }
 381                 if (tprev == NULL)
 382                         SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
 383                 else {
 384                         SLIST_INSERT_AFTER(tprev, t, m_tag_link);
 385                         tprev = t;
 386                 }
 387         }
 388         return 1;
 389 }
 390
 391 /* Initialize tags on an mbuf. */
 392 void
 393 m_tag_init(struct mbuf *m)
 394 {
 395         SLIST_INIT(&m->m_pkthdr.tags);
 396 }
 397
 398 /* Get first tag in chain. */
 399 struct m_tag *
 400 m_tag_first(struct mbuf *m)
 401 {
 402         return SLIST_FIRST(&m->m_pkthdr.tags);
 403 }
 404
 405 /* Get next tag in chain. */
 406 struct m_tag *
 407 m_tag_next(struct mbuf *m, struct m_tag *t)
 408 {
 409         return SLIST_NEXT(t, m_tag_link);
 410 }