FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf2.c
1 /* $NetBSD: uipc_mbuf2.c,v 1.16.2.1 2005/05/06 23:50:22 snj 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 1.16.2.1 2005/05/06 23:50:22 snj 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 o = m_dup(n, off, n->m_len - off, M_DONTWAIT);
132 if (o == NULL) {
133 m_freem(m);
134 return NULL; /* ENOBUFS */
135 }
136 n->m_len = off;
137 o->m_next = n->m_next;
138 n->m_next = o;
139 n = n->m_next;
140 off = 0;
141 goto ok;
142 }
143
144 /*
145 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
146 * and construct contiguous mbuf with m_len == len.
147 * note that hlen + tlen == len, and tlen > 0.
148 */
149 hlen = n->m_len - off;
150 tlen = len - hlen;
151
152 /*
153 * ensure that we have enough trailing data on mbuf chain.
154 * if not, we can do nothing about the chain.
155 */
156 olen = 0;
157 for (o = n->m_next; o != NULL; o = o->m_next)
158 olen += o->m_len;
159 if (hlen + olen < len) {
160 m_freem(m);
161 return NULL; /* mbuf chain too short */
162 }
163
164 /*
165 * easy cases first.
166 * we need to use m_copydata() to get data from <n->m_next, 0>.
167 */
168 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
169 !sharedcluster) {
170 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
171 n->m_len += tlen;
172 m_adj(n->m_next, tlen);
173 goto ok;
174 }
175 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
176 !sharedcluster && n->m_next->m_len >= tlen) {
177 n->m_next->m_data -= hlen;
178 n->m_next->m_len += hlen;
179 memcpy(mtod(n->m_next, caddr_t), mtod(n, caddr_t) + off, hlen);
180 n->m_len -= hlen;
181 n = n->m_next;
182 off = 0;
183 goto ok;
184 }
185
186 /*
187 * now, we need to do the hard way. don't m_copy as there's no room
188 * on both end.
189 */
190 MGET(o, M_DONTWAIT, m->m_type);
191 if (o && len > MLEN) {
192 MCLGET(o, M_DONTWAIT);
193 if ((o->m_flags & M_EXT) == 0) {
194 m_free(o);
195 o = NULL;
196 }
197 }
198 if (!o) {
199 m_freem(m);
200 return NULL; /* ENOBUFS */
201 }
202 /* get hlen from <n, off> into <o, 0> */
203 o->m_len = hlen;
204 memcpy(mtod(o, caddr_t), mtod(n, caddr_t) + off, hlen);
205 n->m_len -= hlen;
206 /* get tlen from <n->m_next, 0> into <o, hlen> */
207 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
208 o->m_len += tlen;
209 m_adj(n->m_next, tlen);
210 o->m_next = n->m_next;
211 n->m_next = o;
212 n = o;
213 off = 0;
214
215 ok:
216 if (offp)
217 *offp = off;
218 return n;
219 }
220
221 /* Get a packet tag structure along with specified data following. */
222 struct m_tag *
223 m_tag_get(int type, int len, int wait)
224 {
225 struct m_tag *t;
226
227 if (len < 0)
228 return (NULL);
229 t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
230 if (t == NULL)
231 return (NULL);
232 t->m_tag_id = type;
233 t->m_tag_len = len;
234 return (t);
235 }
236
237 /* Free a packet tag. */
238 void
239 m_tag_free(struct m_tag *t)
240 {
241
242 free(t, M_PACKET_TAGS);
243 }
244
245 /* Prepend a packet tag. */
246 void
247 m_tag_prepend(struct mbuf *m, struct m_tag *t)
248 {
249
250 SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
251 }
252
253 /* Unlink a packet tag. */
254 void
255 m_tag_unlink(struct mbuf *m, struct m_tag *t)
256 {
257
258 SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
259 }
260
261 /* Unlink and free a packet tag. */
262 void
263 m_tag_delete(struct mbuf *m, struct m_tag *t)
264 {
265
266 m_tag_unlink(m, t);
267 m_tag_free(t);
268 }
269
270 /* Unlink and free a packet tag chain, starting from given tag. */
271 __inline void
272 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
273 {
274 struct m_tag *p, *q;
275
276 if (t != NULL)
277 p = t;
278 else
279 p = SLIST_FIRST(&m->m_pkthdr.tags);
280 if (p == NULL)
281 return;
282 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
283 m_tag_delete(m, q);
284 m_tag_delete(m, p);
285 }
286
287 /*
288 * Strip off all tags that would normally vanish when
289 * passing through a network interface. Only persistent
290 * tags will exist after this; these are expected to remain
291 * so long as the mbuf chain exists, regardless of the
292 * path the mbufs take.
293 */
294 void
295 m_tag_delete_nonpersistent(struct mbuf *m)
296 {
297 /* NetBSD has no persistent tags yet, so just delete all tags. */
298 return m_tag_delete_chain(m, NULL);
299 }
300
301
302 /* Find a tag, starting from a given position. */
303 struct m_tag *
304 m_tag_find(struct mbuf *m, int type, struct m_tag *t)
305 {
306 struct m_tag *p;
307
308 if (t == NULL)
309 p = SLIST_FIRST(&m->m_pkthdr.tags);
310 else
311 p = SLIST_NEXT(t, m_tag_link);
312 while (p != NULL) {
313 if (p->m_tag_id == type)
314 return (p);
315 p = SLIST_NEXT(p, m_tag_link);
316 }
317 return (NULL);
318 }
319
320 /* Copy a single tag. */
321 struct m_tag *
322 m_tag_copy(struct m_tag *t)
323 {
324 struct m_tag *p;
325
326 p = m_tag_get(t->m_tag_id, t->m_tag_len, M_NOWAIT);
327 if (p == NULL)
328 return (NULL);
329 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
330 return (p);
331 }
332
333 /*
334 * Copy two tag chains. The destination mbuf (to) loses any attached
335 * tags even if the operation fails. This should not be a problem, as
336 * m_tag_copy_chain() is typically called with a newly-allocated
337 * destination mbuf.
338 */
339 int
340 m_tag_copy_chain(struct mbuf *to, struct mbuf *from)
341 {
342 struct m_tag *p, *t, *tprev = NULL;
343
344 m_tag_delete_chain(to, NULL);
345 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
346 t = m_tag_copy(p);
347 if (t == NULL) {
348 m_tag_delete_chain(to, NULL);
349 return (0);
350 }
351 if (tprev == NULL)
352 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
353 else
354 SLIST_INSERT_AFTER(tprev, t, m_tag_link);
355 tprev = t;
356 }
357 return (1);
358 }
359
360 /* Initialize tags on an mbuf. */
361 void
362 m_tag_init(struct mbuf *m)
363 {
364
365 SLIST_INIT(&m->m_pkthdr.tags);
366 }
367
368 /* Get first tag in chain. */
369 struct m_tag *
370 m_tag_first(struct mbuf *m)
371 {
372
373 return (SLIST_FIRST(&m->m_pkthdr.tags));
374 }
375
376 /* Get next tag in chain. */
377 struct m_tag *
378 m_tag_next(struct mbuf *m, struct m_tag *t)
379 {
380
381 return (SLIST_NEXT(t, m_tag_link));
382 }
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