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/lock.h> 74 #include <sys/malloc.h> 75 #include <sys/mbuf.h> 76 #include <sys/mutex.h> 77 78 /* 79 * ensure that [off, off + len) is contiguous on the mbuf chain "m". 80 * packet chain before "off" is kept untouched. 81 * if offp == NULL, the target will start at <retval, 0> on resulting chain. 82 * if offp != NULL, the target will start at <retval, *offp> on resulting chain. 83 * 84 * on error return (NULL return value), original "m" will be freed. 85 * 86 * XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf. 87 */ 88 struct mbuf * 89 m_pulldown(struct mbuf *m, int off, int len, int *offp) 90 { 91 struct mbuf *n, *o; 92 int hlen, tlen, olen; 93 int writable; 94 95 /* check invalid arguments. */ 96 if (m == NULL) 97 panic("m == NULL in m_pulldown()"); 98 if (len > MCLBYTES) { 99 m_freem(m); 100 return NULL; /* impossible */ 101 } 102 103 #ifdef PULLDOWN_DEBUG 104 { 105 struct mbuf *t; 106 printf("before:"); 107 for (t = m; t; t = t->m_next) 108 printf(" %d", t->m_len); 109 printf("\n"); 110 } 111 #endif 112 n = m; 113 while (n != NULL && off > 0) { 114 if (n->m_len > off) 115 break; 116 off -= n->m_len; 117 n = n->m_next; 118 } 119 /* be sure to point non-empty mbuf */ 120 while (n != NULL && n->m_len == 0) 121 n = n->m_next; 122 if (!n) { 123 m_freem(m); 124 return NULL; /* mbuf chain too short */ 125 } 126 127 /* 128 * the target data is on <n, off>. 129 * if we got enough data on the mbuf "n", we're done. 130 */ 131 if ((off == 0 || offp) && len <= n->m_len - off) 132 goto ok; 133 134 /* 135 * when len < n->m_len - off and off != 0, it is a special case. 136 * len bytes from <n, off> sits in single mbuf, but the caller does 137 * not like the starting position (off). 138 * chop the current mbuf into two pieces, set off to 0. 139 */ 140 if (len < n->m_len - off) { 141 o = m_copym(n, off, n->m_len - off, M_DONTWAIT); 142 if (o == NULL) { 143 m_freem(m); 144 return NULL; /* ENOBUFS */ 145 } 146 n->m_len = off; 147 o->m_next = n->m_next; 148 n->m_next = o; 149 n = n->m_next; 150 off = 0; 151 goto ok; 152 } 153 154 /* 155 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>, 156 * and construct contiguous mbuf with m_len == len. 157 * note that hlen + tlen == len, and tlen > 0. 158 */ 159 hlen = n->m_len - off; 160 tlen = len - hlen; 161 162 /* 163 * ensure that we have enough trailing data on mbuf chain. 164 * if not, we can do nothing about the chain. 165 */ 166 olen = 0; 167 for (o = n->m_next; o != NULL; o = o->m_next) 168 olen += o->m_len; 169 if (hlen + olen < len) { 170 m_freem(m); 171 return NULL; /* mbuf chain too short */ 172 } 173 174 /* 175 * easy cases first. 176 * we need to use m_copydata() to get data from <n->m_next, 0>. 177 */ 178 /* 179 * XXX: This code is flawed because it considers a "writable" mbuf 180 * data region to require all of the following: 181 * (i) mbuf _has_ to have M_EXT set; if it is just a regular 182 * mbuf, it is still not considered "writable." 183 * (ii) since mbuf has M_EXT, the ext_type _has_ to be 184 * EXT_CLUSTER. Anything else makes it non-writable. 185 * (iii) M_WRITABLE() must evaluate true. 186 * Ideally, the requirement should only be (iii). 187 * 188 * If we're writable, we're sure we're writable, because the ref. count 189 * cannot increase from 1, as that would require posession of mbuf 190 * n by someone else (which is impossible). However, if we're _not_ 191 * writable, we may eventually become writable )if the ref. count drops 192 * to 1), but we'll fail to notice it unless we re-evaluate 193 * M_WRITABLE(). For now, we only evaluate once at the beginning and 194 * live with this. 195 */ 196 /* 197 * XXX: This is dumb. If we're just a regular mbuf with no M_EXT, 198 * then we're not "writable," according to this code. 199 */ 200 writable = 0; 201 if ((n->m_flags & M_EXT) && (n->m_ext.ext_type == EXT_CLUSTER) && 202 M_WRITABLE(n)) 203 writable = 1; 204 205 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen 206 && writable) { 207 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len); 208 n->m_len += tlen; 209 m_adj(n->m_next, tlen); 210 goto ok; 211 } 212 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen 213 && writable) { 214 n->m_next->m_data -= hlen; 215 n->m_next->m_len += hlen; 216 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen); 217 n->m_len -= hlen; 218 n = n->m_next; 219 off = 0; 220 goto ok; 221 } 222 223 /* 224 * now, we need to do the hard way. don't m_copy as there's no room 225 * on both end. 226 */ 227 MGET(o, M_DONTWAIT, m->m_type); 228 if (o == NULL) { 229 m_freem(m); 230 return NULL; /* ENOBUFS */ 231 } 232 if (len > MHLEN) { /* use MHLEN just for safety */ 233 MCLGET(o, M_DONTWAIT); 234 if ((o->m_flags & M_EXT) == 0) { 235 m_freem(m); 236 m_free(o); 237 return NULL; /* ENOBUFS */ 238 } 239 } 240 /* get hlen from <n, off> into <o, 0> */ 241 o->m_len = hlen; 242 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen); 243 n->m_len -= hlen; 244 /* get tlen from <n->m_next, 0> into <o, hlen> */ 245 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len); 246 o->m_len += tlen; 247 m_adj(n->m_next, tlen); 248 o->m_next = n->m_next; 249 n->m_next = o; 250 n = o; 251 off = 0; 252 253 ok: 254 #ifdef PULLDOWN_DEBUG 255 { 256 struct mbuf *t; 257 printf("after:"); 258 for (t = m; t; t = t->m_next) 259 printf("%c%d", t == n ? '*' : ' ', t->m_len); 260 printf(" (off=%d)\n", off); 261 } 262 #endif 263 if (offp) 264 *offp = off; 265 return n; 266 } 267 268 /* 269 * pkthdr.aux chain manipulation. 270 * we don't allow clusters at this moment. 271 */ 272 struct mbuf * 273 m_aux_add(struct mbuf *m, int af, int type) 274 { 275 struct mbuf *n; 276 struct mauxtag *t; 277 278 if ((m->m_flags & M_PKTHDR) == 0) 279 return NULL; 280 281 n = m_aux_find(m, af, type); 282 if (n) 283 return n; 284 285 MGET(n, M_DONTWAIT, m->m_type); 286 if (n == NULL) 287 return NULL; 288 289 t = mtod(n, struct mauxtag *); 290 t->af = af; 291 t->type = type; 292 n->m_data += sizeof(struct mauxtag); 293 n->m_len = 0; 294 n->m_next = m->m_pkthdr.aux; 295 m->m_pkthdr.aux = n; 296 return n; 297 } 298 299 struct mbuf * 300 m_aux_find(struct mbuf *m, int af, int type) 301 { 302 struct mbuf *n; 303 struct mauxtag *t; 304 305 if ((m->m_flags & M_PKTHDR) == 0) 306 return NULL; 307 308 for (n = m->m_pkthdr.aux; n; n = n->m_next) { 309 t = (struct mauxtag *)n->m_dat; 310 if (t->af == af && t->type == type) 311 return n; 312 } 313 return NULL; 314 } 315 316 void 317 m_aux_delete(struct mbuf *m, struct mbuf *victim) 318 { 319 struct mbuf *n, *prev, *next; 320 struct mauxtag *t; 321 322 if ((m->m_flags & M_PKTHDR) == 0) 323 return; 324 325 prev = NULL; 326 n = m->m_pkthdr.aux; 327 while (n) { 328 t = (struct mauxtag *)n->m_dat; 329 next = n->m_next; 330 if (n == victim) { 331 if (prev) 332 prev->m_next = n->m_next; 333 else 334 m->m_pkthdr.aux = n->m_next; 335 n->m_next = NULL; 336 m_free(n); 337 } else 338 prev = n; 339 n = next; 340 } 341 } 342