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 1.11 2005/06/17 19:12:16 dillon 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(m, off, len, offp)
  96         struct mbuf *m;
  97         int off, len;
  98         int *offp;
  99 {
 100         struct mbuf *n, *o;
 101         int hlen, tlen, olen;
 102         int sharedcluster;
 103
 104         /* check invalid arguments. */
 105         if (m == NULL)
 106                 panic("m == NULL in m_pulldown()");
 107         if (len > MCLBYTES) {
 108                 m_freem(m);
 109                 return NULL;    /* impossible */
 110         }
 111
 112 #ifdef PULLDOWN_DEBUG
 113     {
 114         struct mbuf *t;
 115         printf("before:");
 116         for (t = m; t; t = t->m_next)
 117                 printf(" %d", t->m_len);
 118         printf("\n");
 119     }
 120 #endif
 121         n = m;
 122         while (n != NULL && off > 0) {
 123                 if (n->m_len > off)
 124                         break;
 125                 off -= n->m_len;
 126                 n = n->m_next;
 127         }
 128         /* be sure to point non-empty mbuf */
 129         while (n != NULL && n->m_len == 0)
 130                 n = n->m_next;
 131         if (!n) {
 132                 m_freem(m);
 133                 return NULL;    /* mbuf chain too short */
 134         }
 135
 136         sharedcluster = (m_sharecount(n) > 1);
 137
 138         /*
 139          * the target data is on <n, off>.
 140          * if we got enough data on the mbuf "n", we're done.
 141          */
 142         if ((off == 0 || offp) && len <= n->m_len - off && !sharedcluster)
 143                 goto ok;
 144
 145         /*
 146          * when len <= n->m_len - off and off != 0, it is a special case.
 147          * len bytes from <n, off> sits in single mbuf, but the caller does
 148          * not like the starting position (off).
 149          * chop the current mbuf into two pieces, set off to 0.
 150          */
 151         if (len <= n->m_len - off) {
 152                 o = m_dup1(n, off, n->m_len - off, MB_DONTWAIT);
 153                 if (o == NULL) {
 154                         m_freem(m);
 155                         return NULL;    /* ENOBUFS */
 156                 }
 157                 n->m_len = off;
 158                 o->m_next = n->m_next;
 159                 n->m_next = o;
 160                 n = n->m_next;
 161                 off = 0;
 162                 goto ok;
 163         }
 164
 165         /*
 166          * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
 167          * and construct contiguous mbuf with m_len == len.
 168          * note that hlen + tlen == len, and tlen > 0.
 169          */
 170         hlen = n->m_len - off;
 171         tlen = len - hlen;
 172
 173         /*
 174          * ensure that we have enough trailing data on mbuf chain.
 175          * if not, we can do nothing about the chain.
 176          */
 177         olen = 0;
 178         for (o = n->m_next; o != NULL; o = o->m_next)
 179                 olen += o->m_len;
 180         if (hlen + olen < len) {
 181                 m_freem(m);
 182                 return NULL;    /* mbuf chain too short */
 183         }
 184
 185         /*
 186          * easy cases first.
 187          * we need to use m_copydata() to get data from <n->m_next, 0>.
 188          */
 189         if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
 190             !sharedcluster) {
 191                 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
 192                 n->m_len += tlen;
 193                 m_adj(n->m_next, tlen);
 194                 goto ok;
 195         }
 196         if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
 197             !sharedcluster) {
 198                 n->m_next->m_data -= hlen;
 199                 n->m_next->m_len += hlen;
 200                 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
 201                 n->m_len -= hlen;
 202                 n = n->m_next;
 203                 off = 0;
 204                 goto ok;
 205         }
 206
 207         /*
 208          * now, we need to do the hard way.  don't m_copy as there's no room
 209          * on both end.
 210          */
 211         o = m_getl(len, MB_DONTWAIT, m->m_type, 0, NULL);
 212         if (!o) {
 213                 m_freem(m);
 214                 return NULL;    /* ENOBUFS */
 215         }
 216         /* get hlen from <n, off> into <o, 0> */
 217         o->m_len = hlen;
 218         bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
 219         n->m_len -= hlen;
 220         /* get tlen from <n->m_next, 0> into <o, hlen> */
 221         m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
 222         o->m_len += tlen;
 223         m_adj(n->m_next, tlen);
 224         o->m_next = n->m_next;
 225         n->m_next = o;
 226         n = o;
 227         off = 0;
 228
 229 ok:
 230 #ifdef PULLDOWN_DEBUG
 231     {
 232         struct mbuf *t;
 233         printf("after:");
 234         for (t = m; t; t = t->m_next)
 235                 printf("%c%d", t == n ? '*' : ' ', t->m_len);
 236         printf(" (off=%d)\n", off);
 237     }
 238 #endif
 239         if (offp)
 240                 *offp = off;
 241         return n;
 242 }
 243
 244 static struct mbuf *
 245 m_dup1(m, off, len, wait)
 246         struct mbuf *m;
 247         int off;
 248         int len;
 249         int wait;
 250 {
 251         struct mbuf *n;
 252
 253         if (len > MCLBYTES)
 254                 return NULL;
 255         n = m_getl(len, wait, m->m_type, m->m_flags, NULL);
 256         if (!n)
 257                 return NULL;
 258         if (off == 0 && (m->m_flags & M_PKTHDR) && !m_dup_pkthdr(n, m, wait)) {
 259                 m_free(n);
 260                 return NULL;
 261         }
 262         m_copydata(m, off, len, mtod(n, caddr_t));
 263         return n;
 264 }
 265
 266 /* Get a packet tag structure along with specified data following. */
 267 struct m_tag *
 268 m_tag_alloc(u_int32_t cookie, int type, int len, int wait)
 269 {
 270         struct m_tag *t;
 271
 272         if (len < 0)
 273                 return NULL;
 274         t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS,
 275                    wait != MB_WAIT ? M_NOWAIT : M_WAITOK);
 276         if (t == NULL)
 277                 return NULL;
 278         t->m_tag_id = type;
 279         t->m_tag_len = len;
 280         t->m_tag_cookie = cookie;
 281         return t;
 282 }
 283
 284
 285 /* Free a packet tag. */
 286 void
 287 m_tag_free(struct m_tag *t)
 288 {
 289         free(t, M_PACKET_TAGS);
 290 }
 291
 292 /* Prepend a packet tag. */
 293 void
 294 m_tag_prepend(struct mbuf *m, struct m_tag *t)
 295 {
 296         KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t));
 297         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_prepend: mbuf %p non-header", m));
 298         SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
 299 }
 300
 301 /* Unlink a packet tag. */
 302 void
 303 m_tag_unlink(struct mbuf *m, struct m_tag *t)
 304 {
 305         KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t));
 306         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_unlink: mbuf %p non-header", m));
 307         SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
 308 }
 309
 310 /* Unlink and free a packet tag. */
 311 void
 312 m_tag_delete(struct mbuf *m, struct m_tag *t)
 313 {
 314         KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
 315         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete: mbuf %p non-header", m));
 316         m_tag_unlink(m, t);
 317         m_tag_free(t);
 318 }
 319
 320 /* Unlink and free a packet tag chain, starting from given tag. */
 321 void
 322 m_tag_delete_chain(struct mbuf *m)
 323 {
 324         struct m_tag *p, *q;
 325
 326         KASSERT(m, ("m_tag_delete_chain: null mbuf"));
 327         KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete_chain: mbuf %p non-header", m));
 328         p = SLIST_FIRST(&m->m_pkthdr.tags);
 329         if (p == NULL)
 330                 return;
 331         while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
 332                 m_tag_delete(m, q);
 333         m_tag_delete(m, p);
 334 }
 335
 336 /* Find a tag, starting from a given position. */
 337 struct m_tag *
 338 m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t)
 339 {
 340         struct m_tag *p;
 341
 342         KASSERT(m, ("m_tag_find: null mbuf"));
 343         if (t == NULL)
 344                 p = SLIST_FIRST(&m->m_pkthdr.tags);
 345         else
 346                 p = SLIST_NEXT(t, m_tag_link);
 347         while (p != NULL) {
 348                 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
 349                         return p;
 350                 p = SLIST_NEXT(p, m_tag_link);
 351         }
 352         return NULL;
 353 }
 354
 355 /* Copy a single tag. */
 356 struct m_tag *
 357 m_tag_copy(struct m_tag *t, int how)
 358 {
 359         struct m_tag *p;
 360
 361         KASSERT(t, ("m_tag_copy: null tag"));
 362         p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
 363         if (p == NULL)
 364                 return (NULL);
 365         bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
 366         return p;
 367 }
 368
 369 /*
 370  * Copy two tag chains. The destination mbuf (to) loses any attached
 371  * tags even if the operation fails. This should not be a problem, as
 372  * m_tag_copy_chain() is typically called with a newly-allocated
 373  * destination mbuf.
 374  */
 375 int
 376 m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how)
 377 {
 378         struct m_tag *p, *t, *tprev = NULL;
 379
 380         KASSERT(to && from,
 381                 ("m_tag_copy: null argument, to %p from %p", to, from));
 382         m_tag_delete_chain(to);
 383         SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
 384                 t = m_tag_copy(p, how);
 385                 if (t == NULL) {
 386                         m_tag_delete_chain(to);
 387                         return 0;
 388                 }
 389                 if (tprev == NULL)
 390                         SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
 391                 else {
 392                         SLIST_INSERT_AFTER(tprev, t, m_tag_link);
 393                         tprev = t;
 394                 }
 395         }
 396         return 1;
 397 }
 398
 399 /* Initialize tags on an mbuf. */
 400 void
 401 m_tag_init(struct mbuf *m)
 402 {
 403         SLIST_INIT(&m->m_pkthdr.tags);
 404 }
 405
 406 /* Get first tag in chain. */
 407 struct m_tag *
 408 m_tag_first(struct mbuf *m)
 409 {
 410         return SLIST_FIRST(&m->m_pkthdr.tags);
 411 }
 412
 413 /* Get next tag in chain. */
 414 struct m_tag *
 415 m_tag_next(struct mbuf *m, struct m_tag *t)
 416 {
 417         return SLIST_NEXT(t, m_tag_link);
 418 }