1 /* $FreeBSD$ */ 2 /* $KAME: uipc_mbuf2.c,v 1.15 2000/02/22 14:01:37 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. All advertising materials mentioning features or use of this software 47 * must display the following acknowledgement: 48 * This product includes software developed by the University of 49 * California, Berkeley and its contributors. 50 * 4. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 * 66 * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95 67 */ 68 69 /*#define PULLDOWN_DEBUG*/ 70 71 #include <sys/param.h> 72 #include <sys/systm.h> 73 #include <sys/malloc.h> 74 #include <sys/mbuf.h> 75 76 /* 77 * ensure that [off, off + len) is contiguous on the mbuf chain "m". 78 * packet chain before "off" is kept untouched. 79 * if offp == NULL, the target will start at <retval, 0> on resulting chain. 80 * if offp != NULL, the target will start at <retval, *offp> on resulting chain. 81 * 82 * on error return (NULL return value), original "m" will be freed. 83 * 84 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. 85 */ 86 struct mbuf * 87 m_pulldown(m, off, len, offp) 88 struct mbuf *m; 89 int off, len; 90 int *offp; 91 { 92 struct mbuf *n, *o; 93 int hlen, tlen, olen; 94 int writable; 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 printf("before:"); 108 for (t = m; t; t = t->m_next) 109 printf(" %d", t->m_len); 110 printf("\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 /* 129 * the target data is on <n, off>. 130 * if we got enough data on the mbuf "n", we're done. 131 */ 132 if ((off == 0 || offp) && len <= n->m_len - off) 133 goto ok; 134 135 /* 136 * when len < n->m_len - off and off != 0, it is a special case. 137 * len bytes from <n, off> sits in single mbuf, but the caller does 138 * not like the starting position (off). 139 * chop the current mbuf into two pieces, set off to 0. 140 */ 141 if (len < n->m_len - off) { 142 o = m_copym(n, off, n->m_len - off, M_DONTWAIT); 143 if (o == NULL) { 144 m_freem(m); 145 return NULL; /* ENOBUFS */ 146 } 147 n->m_len = off; 148 o->m_next = n->m_next; 149 n->m_next = o; 150 n = n->m_next; 151 off = 0; 152 goto ok; 153 } 154 155 /* 156 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, 157 * and construct contiguous mbuf with m_len == len. 158 * note that hlen + tlen == len, and tlen > 0. 159 */ 160 hlen = n->m_len - off; 161 tlen = len - hlen; 162 163 /* 164 * ensure that we have enough trailing data on mbuf chain. 165 * if not, we can do nothing about the chain. 166 */ 167 olen = 0; 168 for (o = n->m_next; o != NULL; o = o->m_next) 169 olen += o->m_len; 170 if (hlen + olen < len) { 171 m_freem(m); 172 return NULL; /* mbuf chain too short */ 173 } 174 175 /* 176 * easy cases first. 177 * we need to use m_copydata() to get data from <n->m_next, 0>. 178 */ 179 /* 180 * XXX: This code is flawed because it considers a "writable" mbuf 181 * data region to require all of the following: 182 * (i) mbuf _has_ to have M_EXT set; if it is just a regular 183 * mbuf, it is still not considered "writable." 184 * (ii) since mbuf has M_EXT, the ext_type _has_ to be 185 * EXT_CLUSTER. Anything else makes it non-writable. 186 * (iii) M_WRITABLE() must evaluate true. 187 * Ideally, the requirement should only be (iii). 188 * 189 * If we're writable, we're sure we're writable, because the ref. count 190 * cannot increase from 1, as that would require posession of mbuf 191 * n by someone else (which is impossible). However, if we're _not_ 192 * writable, we may eventually become writable )if the ref. count drops 193 * to 1), but we'll fail to notice it unless we re-evaluate 194 * M_WRITABLE(). For now, we only evaluate once at the beginning and 195 * live with this. 196 */ 197 /* 198 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT, 199 * then we're not "writable," according to this code. 200 */ 201 writable = 0; 202 if ((n->m_flags & M_EXT) && (n->m_ext.ext_type == EXT_CLUSTER) && 203 M_WRITABLE(n)) 204 writable = 1; 205 206 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen 207 && writable) { 208 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); 209 n->m_len += tlen; 210 m_adj(n->m_next, tlen); 211 goto ok; 212 } 213 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen 214 && writable) { 215 n->m_next->m_data -= hlen; 216 n->m_next->m_len += hlen; 217 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); 218 n->m_len -= hlen; 219 n = n->m_next; 220 off = 0; 221 goto ok; 222 } 223 224 /* 225 * now, we need to do the hard way. don't m_copy as there's no room 226 * on both end. 227 */ 228 MGET(o, M_DONTWAIT, m->m_type); 229 if (o == NULL) { 230 m_freem(m); 231 return NULL; /* ENOBUFS */ 232 } 233 if (len > MHLEN) { /* use MHLEN just for safety */ 234 MCLGET(o, M_DONTWAIT); 235 if ((o->m_flags & M_EXT) == 0) { 236 m_freem(m); 237 m_free(o); 238 return NULL; /* ENOBUFS */ 239 } 240 } 241 /* get hlen from <n, off> into <o, 0> */ 242 o->m_len = hlen; 243 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 244 n->m_len -= hlen; 245 /* get tlen from <n->m_next, 0> into <o, hlen> */ 246 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 247 o->m_len += tlen; 248 m_adj(n->m_next, tlen); 249 o->m_next = n->m_next; 250 n->m_next = o; 251 n = o; 252 off = 0; 253 254 ok: 255 #ifdef PULLDOWN_DEBUG 256 { 257 struct mbuf *t; 258 printf("after:"); 259 for (t = m; t; t = t->m_next) 260 printf("%c%d", t == n ? '*' : ' ', t->m_len); 261 printf(" (off=%d)\n", off); 262 } 263 #endif 264 if (offp) 265 *offp = off; 266 return n; 267 } 268 269 /* 270 * pkthdr.aux chain manipulation. 271 * we don't allow clusters at this moment. 272 */ 273 struct mbuf * 274 m_aux_add(m, af, type) 275 struct mbuf *m; 276 int af, type; 277 { 278 struct mbuf *n; 279 struct mauxtag *t; 280 281 if ((m->m_flags & M_PKTHDR) == 0) 282 return NULL; 283 284 n = m_aux_find(m, af, type); 285 if (n) 286 return n; 287 288 MGET(n, M_DONTWAIT, m->m_type); 289 if (n == NULL) 290 return NULL; 291 292 t = mtod(n, struct mauxtag *); 293 t->af = af; 294 t->type = type; 295 n->m_data += sizeof(struct mauxtag); 296 n->m_len = 0; 297 n->m_next = m->m_pkthdr.aux; 298 m->m_pkthdr.aux = n; 299 return n; 300 } 301 302 struct mbuf * 303 m_aux_find(m, af, type) 304 struct mbuf *m; 305 int af, type; 306 { 307 struct mbuf *n; 308 struct mauxtag *t; 309 310 if ((m->m_flags & M_PKTHDR) == 0) 311 return NULL; 312 313 for (n = m->m_pkthdr.aux; n; n = n->m_next) { 314 t = (struct mauxtag *)n->m_dat; 315 if (t->af == af && t->type == type) 316 return n; 317 } 318 return NULL; 319 } 320 321 void 322 m_aux_delete(m, victim) 323 struct mbuf *m; 324 struct mbuf *victim; 325 { 326 struct mbuf *n, *prev, *next; 327 struct mauxtag *t; 328 329 if ((m->m_flags & M_PKTHDR) == 0) 330 return; 331 332 prev = NULL; 333 n = m->m_pkthdr.aux; 334 while (n) { 335 t = (struct mauxtag *)n->m_dat; 336 next = n->m_next; 337 if (n == victim) { 338 if (prev) 339 prev->m_next = n->m_next; 340 else 341 m->m_pkthdr.aux = n->m_next; 342 n->m_next = NULL; 343 m_free(n); 344 } else 345 prev = n; 346 n = next; 347 } 348 } 349