sys/kern/uipc_mbuf2.c

   1 /*      $NetBSD: uipc_mbuf2.c,v 1.27 2009/03/18 17:06:51 cegger Exp $   */
   2 /*      $KAME: uipc_mbuf2.c,v 1.29 2001/02/14 13:42:10 itojun Exp $     */
   3
   4 /*
   5  * Copyright (C) 1999 WIDE Project.
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the project nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 /*
  34  * Copyright (c) 1982, 1986, 1988, 1991, 1993
  35  *      The Regents of the University of California.  All rights reserved.
  36  *
  37  * Redistribution and use in source and binary forms, with or without
  38  * modification, are permitted provided that the following conditions
  39  * are met:
  40  * 1. Redistributions of source code must retain the above copyright
  41  *    notice, this list of conditions and the following disclaimer.
  42  * 2. Redistributions in binary form must reproduce the above copyright
  43  *    notice, this list of conditions and the following disclaimer in the
  44  *    documentation and/or other materials provided with the distribution.
  45  * 3. Neither the name of the University nor the names of its contributors
  46  *    may be used to endorse or promote products derived from this software
  47  *    without specific prior written permission.
  48  *
  49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  59  * SUCH DAMAGE.
  60  *
  61  *      @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
  62  */
  63
  64 #include <sys/cdefs.h>
  65 __KERNEL_RCSID(0, "$NetBSD: uipc_mbuf2.c,v 1.27 2009/03/18 17:06:51 cegger Exp $");
  66
  67 #include <sys/param.h>
  68 #include <sys/systm.h>
  69 #include <sys/proc.h>
  70 #include <sys/malloc.h>
  71 #include <sys/mbuf.h>
  72
  73 MALLOC_DEFINE(M_PACKET_TAGS, "packet tags", "Packet-attached information");
  74
  75 /*
  76  * ensure that [off, off + len) is contiguous on the mbuf chain "m".
  77  * packet chain before "off" is kept untouched.
  78  * if offp == NULL, the target will start at <retval, 0> on resulting chain.
  79  * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
  80  *
  81  * on error return (NULL return value), original "m" will be freed.
  82  *
  83  * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
  84  */
  85 struct mbuf *
  86 m_pulldown(struct mbuf *m, int off, int len, int *offp)
  87 {
  88         struct mbuf *n, *o;
  89         int hlen, tlen, olen;
  90         int sharedcluster;
  91
  92         /* check invalid arguments. */
  93         if (m == NULL)
  94                 panic("m == NULL in m_pulldown()");
  95         if (len > MCLBYTES) {
  96                 m_freem(m);
  97                 return NULL;    /* impossible */
  98         }
  99
 100         n = m;
 101         while (n != NULL && off > 0) {
 102                 if (n->m_len > off)
 103                         break;
 104                 off -= n->m_len;
 105                 n = n->m_next;
 106         }
 107         /* be sure to point non-empty mbuf */
 108         while (n != NULL && n->m_len == 0)
 109                 n = n->m_next;
 110         if (!n) {
 111                 m_freem(m);
 112                 return NULL;    /* mbuf chain too short */
 113         }
 114
 115         sharedcluster = M_READONLY(n);
 116
 117         /*
 118          * the target data is on <n, off>.
 119          * if we got enough data on the mbuf "n", we're done.
 120          */
 121         if ((off == 0 || offp) && len <= n->m_len - off && !sharedcluster)
 122                 goto ok;
 123
 124         /*
 125          * when len <= n->m_len - off and off != 0, it is a special case.
 126          * len bytes from <n, off> sits in single mbuf, but the caller does
 127          * not like the starting position (off).
 128          * chop the current mbuf into two pieces, set off to 0.
 129          */
 130         if (len <= n->m_len - off) {
 131                 struct mbuf *mlast;
 132
 133                 o = m_dup(n, off, n->m_len - off, M_DONTWAIT);
 134                 if (o == NULL) {
 135                         m_freem(m);
 136                         return NULL;    /* ENOBUFS */
 137                 }
 138                 KASSERT(o->m_len >= len);
 139                 for (mlast = o; mlast->m_next != NULL; mlast = mlast->m_next)
 140                         ;
 141                 n->m_len = off;
 142                 mlast->m_next = n->m_next;
 143                 n->m_next = o;
 144                 n = o;
 145                 off = 0;
 146                 goto ok;
 147         }
 148
 149         /*
 150          * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
 151          * and construct contiguous mbuf with m_len == len.
 152          * note that hlen + tlen == len, and tlen > 0.
 153          */
 154         hlen = n->m_len - off;
 155         tlen = len - hlen;
 156
 157         /*
 158          * ensure that we have enough trailing data on mbuf chain.
 159          * if not, we can do nothing about the chain.
 160          */
 161         olen = 0;
 162         for (o = n->m_next; o != NULL; o = o->m_next)
 163                 olen += o->m_len;
 164         if (hlen + olen < len) {
 165                 m_freem(m);
 166                 return NULL;    /* mbuf chain too short */
 167         }
 168
 169         /*
 170          * easy cases first.
 171          * we need to use m_copydata() to get data from <n->m_next, 0>.
 172          */
 173         if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
 174             !sharedcluster) {
 175                 m_copydata(n->m_next, 0, tlen, mtod(n, char *) + n->m_len);
 176                 n->m_len += tlen;
 177                 m_adj(n->m_next, tlen);
 178                 goto ok;
 179         }
 180         if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
 181             !sharedcluster && n->m_next->m_len >= tlen) {
 182                 n->m_next->m_data -= hlen;
 183                 n->m_next->m_len += hlen;
 184                 memcpy(mtod(n->m_next, void *), mtod(n, char *) + off, hlen);
 185                 n->m_len -= hlen;
 186                 n = n->m_next;
 187                 off = 0;
 188                 goto ok;
 189         }
 190
 191         /*
 192          * now, we need to do the hard way.  don't m_copy as there's no room
 193          * on both end.
 194          */
 195         MGET(o, M_DONTWAIT, m->m_type);
 196         if (o && len > MLEN) {
 197                 MCLGET(o, M_DONTWAIT);
 198                 if ((o->m_flags & M_EXT) == 0) {
 199                         m_free(o);
 200                         o = NULL;
 201                 }
 202         }
 203         if (!o) {
 204                 m_freem(m);
 205                 return NULL;    /* ENOBUFS */
 206         }
 207         /* get hlen from <n, off> into <o, 0> */
 208         o->m_len = hlen;
 209         memcpy(mtod(o, void *), mtod(n, char *) + off, hlen);
 210         n->m_len -= hlen;
 211         /* get tlen from <n->m_next, 0> into <o, hlen> */
 212         m_copydata(n->m_next, 0, tlen, mtod(o, char *) + o->m_len);
 213         o->m_len += tlen;
 214         m_adj(n->m_next, tlen);
 215         o->m_next = n->m_next;
 216         n->m_next = o;
 217         n = o;
 218         off = 0;
 219
 220 ok:
 221         if (offp)
 222                 *offp = off;
 223         return n;
 224 }
 225
 226 /*
 227  * FreeBSD 4.6 introduced m_getcl(), which performs `fast' allocation
 228  * mbuf clusters from a cache of recently-freed clusters. (If the cache
 229  * is empty, new clusters are allocated en-masse).
 230  * On NetBSD, for now, implement the `cache' as a function
 231  * using normal NetBSD mbuf/cluster allocation macros. Replace this
 232  * with fast-cache code, if and when NetBSD implements one.
 233  */
 234 struct mbuf *
 235 m_getcl(int how, int type, int flags)
 236 {
 237         struct mbuf *mp;
 238
 239         if ((flags & M_PKTHDR) != 0)
 240                 MGETHDR(mp, how, type);
 241         else
 242                 MGET(mp, how, type);
 243
 244         if (mp == NULL)
 245                 return NULL;
 246
 247         MCLGET(mp, how);
 248         if ((mp->m_flags & M_EXT) != 0)
 249                 return mp;
 250
 251         m_free(mp);
 252         return NULL;
 253 }
 254
 255 /* Get a packet tag structure along with specified data following. */
 256 struct m_tag *
 257 m_tag_get(int type, int len, int wait)
 258 {
 259         struct m_tag *t;
 260
 261         if (len < 0)
 262                 return (NULL);
 263         t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
 264         if (t == NULL)
 265                 return (NULL);
 266         t->m_tag_id = type;
 267         t->m_tag_len = len;
 268         return (t);
 269 }
 270
 271 /* Free a packet tag. */
 272 void
 273 m_tag_free(struct m_tag *t)
 274 {
 275
 276         free(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
 284         SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
 285 }
 286
 287 /* Unlink a packet tag. */
 288 void
 289 m_tag_unlink(struct mbuf *m, struct m_tag *t)
 290 {
 291
 292         SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
 293 }
 294
 295 /* Unlink and free a packet tag. */
 296 void
 297 m_tag_delete(struct mbuf *m, struct m_tag *t)
 298 {
 299
 300         m_tag_unlink(m, t);
 301         m_tag_free(t);
 302 }
 303
 304 /* Unlink and free a packet tag chain, starting from given tag. */
 305 void
 306 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
 307 {
 308         struct m_tag *p, *q;
 309
 310         if (t != NULL)
 311                 p = t;
 312         else
 313                 p = SLIST_FIRST(&m->m_pkthdr.tags);
 314         if (p == NULL)
 315                 return;
 316         while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
 317                 m_tag_delete(m, q);
 318         m_tag_delete(m, p);
 319 }
 320
 321 /*
 322  * Strip off all tags that would normally vanish when
 323  * passing through a network interface.  Only persistent
 324  * tags will exist after this; these are expected to remain
 325  * so long as the mbuf chain exists, regardless of the
 326  * path the mbufs take.
 327  */
 328 void
 329 m_tag_delete_nonpersistent(struct mbuf *m)
 330 {
 331         /* NetBSD has no persistent tags yet, so just delete all tags. */
 332         m_tag_delete_chain(m, NULL);
 333 }
 334
 335
 336 /* Find a tag, starting from a given position. */
 337 struct m_tag *
 338 m_tag_find(struct mbuf *m, int type, struct m_tag *t)
 339 {
 340         struct m_tag *p;
 341
 342         if (t == NULL)
 343                 p = SLIST_FIRST(&m->m_pkthdr.tags);
 344         else
 345                 p = SLIST_NEXT(t, m_tag_link);
 346         while (p != NULL) {
 347                 if (p->m_tag_id == type)
 348                         return (p);
 349                 p = SLIST_NEXT(p, m_tag_link);
 350         }
 351         return (NULL);
 352 }
 353
 354 /* Copy a single tag. */
 355 struct m_tag *
 356 m_tag_copy(struct m_tag *t)
 357 {
 358         struct m_tag *p;
 359
 360         p = m_tag_get(t->m_tag_id, t->m_tag_len, M_NOWAIT);
 361         if (p == NULL)
 362                 return (NULL);
 363         memcpy(p + 1, t + 1, t->m_tag_len); /* Copy the data */
 364         return (p);
 365 }
 366
 367 /*
 368  * Copy two tag chains. The destination mbuf (to) loses any attached
 369  * tags even if the operation fails. This should not be a problem, as
 370  * m_tag_copy_chain() is typically called with a newly-allocated
 371  * destination mbuf.
 372  */
 373 int
 374 m_tag_copy_chain(struct mbuf *to, struct mbuf *from)
 375 {
 376         struct m_tag *p, *t, *tprev = NULL;
 377
 378         m_tag_delete_chain(to, NULL);
 379         SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
 380                 t = m_tag_copy(p);
 381                 if (t == NULL) {
 382                         m_tag_delete_chain(to, NULL);
 383                         return (0);
 384                 }
 385                 if (tprev == NULL)
 386                         SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
 387                 else
 388                         SLIST_INSERT_AFTER(tprev, t, m_tag_link);
 389                 tprev = t;
 390         }
 391         return (1);
 392 }
 393
 394 /* Initialize tags on an mbuf. */
 395 void
 396 m_tag_init(struct mbuf *m)
 397 {
 398
 399         SLIST_INIT(&m->m_pkthdr.tags);
 400 }
 401
 402 /* Get first tag in chain. */
 403 struct m_tag *
 404 m_tag_first(struct mbuf *m)
 405 {
 406
 407         return (SLIST_FIRST(&m->m_pkthdr.tags));
 408 }
 409
 410 /* Get next tag in chain. */
 411 struct m_tag *
 412 m_tag_next(struct mbuf *m, struct m_tag *t)
 413 {
 414
 415         return (SLIST_NEXT(t, m_tag_link));
 416 }