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