FreeBSD/Linux Kernel Cross Reference
sys/netinet6/frag6.c
1 /*-
2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the project nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: releng/7.3/sys/netinet6/frag6.c 182632 2008-09-01 19:23:04Z obrien $");
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/malloc.h>
38 #include <sys/mbuf.h>
39 #include <sys/domain.h>
40 #include <sys/protosw.h>
41 #include <sys/socket.h>
42 #include <sys/errno.h>
43 #include <sys/time.h>
44 #include <sys/kernel.h>
45 #include <sys/syslog.h>
46
47 #include <net/if.h>
48 #include <net/route.h>
49
50 #include <netinet/in.h>
51 #include <netinet/in_var.h>
52 #include <netinet/ip6.h>
53 #include <netinet6/ip6_var.h>
54 #include <netinet/icmp6.h>
55 #include <netinet/in_systm.h> /* for ECN definitions */
56 #include <netinet/ip.h> /* for ECN definitions */
57
58 /*
59 * Define it to get a correct behavior on per-interface statistics.
60 * You will need to perform an extra routing table lookup, per fragment,
61 * to do it. This may, or may not be, a performance hit.
62 */
63 #define IN6_IFSTAT_STRICT
64
65 static void frag6_enq(struct ip6asfrag *, struct ip6asfrag *);
66 static void frag6_deq(struct ip6asfrag *);
67 static void frag6_insque(struct ip6q *, struct ip6q *);
68 static void frag6_remque(struct ip6q *);
69 static void frag6_freef(struct ip6q *);
70
71 static struct mtx ip6qlock;
72 /*
73 * These fields all protected by ip6qlock.
74 */
75 static u_int frag6_nfragpackets;
76 static u_int frag6_nfrags;
77 static struct ip6q ip6q; /* ip6 reassemble queue */
78
79 #define IP6Q_LOCK_INIT() mtx_init(&ip6qlock, "ip6qlock", NULL, MTX_DEF);
80 #define IP6Q_LOCK() mtx_lock(&ip6qlock)
81 #define IP6Q_TRYLOCK() mtx_trylock(&ip6qlock)
82 #define IP6Q_LOCK_ASSERT() mtx_assert(&ip6qlock, MA_OWNED)
83 #define IP6Q_UNLOCK() mtx_unlock(&ip6qlock)
84
85 static MALLOC_DEFINE(M_FTABLE, "fragment", "fragment reassembly header");
86
87 /*
88 * Initialise reassembly queue and fragment identifier.
89 */
90 static void
91 frag6_change(void *tag)
92 {
93
94 ip6_maxfragpackets = nmbclusters / 4;
95 ip6_maxfrags = nmbclusters / 4;
96 }
97
98 void
99 frag6_init(void)
100 {
101
102 ip6_maxfragpackets = nmbclusters / 4;
103 ip6_maxfrags = nmbclusters / 4;
104 EVENTHANDLER_REGISTER(nmbclusters_change,
105 frag6_change, NULL, EVENTHANDLER_PRI_ANY);
106
107 IP6Q_LOCK_INIT();
108
109 ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
110 }
111
112 /*
113 * In RFC2460, fragment and reassembly rule do not agree with each other,
114 * in terms of next header field handling in fragment header.
115 * While the sender will use the same value for all of the fragmented packets,
116 * receiver is suggested not to check the consistency.
117 *
118 * fragment rule (p20):
119 * (2) A Fragment header containing:
120 * The Next Header value that identifies the first header of
121 * the Fragmentable Part of the original packet.
122 * -> next header field is same for all fragments
123 *
124 * reassembly rule (p21):
125 * The Next Header field of the last header of the Unfragmentable
126 * Part is obtained from the Next Header field of the first
127 * fragment's Fragment header.
128 * -> should grab it from the first fragment only
129 *
130 * The following note also contradicts with fragment rule - noone is going to
131 * send different fragment with different next header field.
132 *
133 * additional note (p22):
134 * The Next Header values in the Fragment headers of different
135 * fragments of the same original packet may differ. Only the value
136 * from the Offset zero fragment packet is used for reassembly.
137 * -> should grab it from the first fragment only
138 *
139 * There is no explicit reason given in the RFC. Historical reason maybe?
140 */
141 /*
142 * Fragment input
143 */
144 int
145 frag6_input(struct mbuf **mp, int *offp, int proto)
146 {
147 struct mbuf *m = *mp, *t;
148 struct ip6_hdr *ip6;
149 struct ip6_frag *ip6f;
150 struct ip6q *q6;
151 struct ip6asfrag *af6, *ip6af, *af6dwn;
152 #ifdef IN6_IFSTAT_STRICT
153 struct in6_ifaddr *ia;
154 #endif
155 int offset = *offp, nxt, i, next;
156 int first_frag = 0;
157 int fragoff, frgpartlen; /* must be larger than u_int16_t */
158 struct ifnet *dstifp;
159 u_int8_t ecn, ecn0;
160 #if 0
161 char ip6buf[INET6_ADDRSTRLEN];
162 #endif
163
164 ip6 = mtod(m, struct ip6_hdr *);
165 #ifndef PULLDOWN_TEST
166 IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
167 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
168 #else
169 IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
170 if (ip6f == NULL)
171 return (IPPROTO_DONE);
172 #endif
173
174 dstifp = NULL;
175 #ifdef IN6_IFSTAT_STRICT
176 /* find the destination interface of the packet. */
177 if ((ia = ip6_getdstifaddr(m)) != NULL)
178 dstifp = ia->ia_ifp;
179 #else
180 /* we are violating the spec, this is not the destination interface */
181 if ((m->m_flags & M_PKTHDR) != 0)
182 dstifp = m->m_pkthdr.rcvif;
183 #endif
184
185 /* jumbo payload can't contain a fragment header */
186 if (ip6->ip6_plen == 0) {
187 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
188 in6_ifstat_inc(dstifp, ifs6_reass_fail);
189 return IPPROTO_DONE;
190 }
191
192 /*
193 * check whether fragment packet's fragment length is
194 * multiple of 8 octets.
195 * sizeof(struct ip6_frag) == 8
196 * sizeof(struct ip6_hdr) = 40
197 */
198 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
199 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
200 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
201 offsetof(struct ip6_hdr, ip6_plen));
202 in6_ifstat_inc(dstifp, ifs6_reass_fail);
203 return IPPROTO_DONE;
204 }
205
206 ip6stat.ip6s_fragments++;
207 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
208
209 /* offset now points to data portion */
210 offset += sizeof(struct ip6_frag);
211
212 IP6Q_LOCK();
213
214 /*
215 * Enforce upper bound on number of fragments.
216 * If maxfrag is 0, never accept fragments.
217 * If maxfrag is -1, accept all fragments without limitation.
218 */
219 if (ip6_maxfrags < 0)
220 ;
221 else if (frag6_nfrags >= (u_int)ip6_maxfrags)
222 goto dropfrag;
223
224 for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
225 if (ip6f->ip6f_ident == q6->ip6q_ident &&
226 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
227 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
228 break;
229
230 if (q6 == &ip6q) {
231 /*
232 * the first fragment to arrive, create a reassembly queue.
233 */
234 first_frag = 1;
235
236 /*
237 * Enforce upper bound on number of fragmented packets
238 * for which we attempt reassembly;
239 * If maxfragpackets is 0, never accept fragments.
240 * If maxfragpackets is -1, accept all fragments without
241 * limitation.
242 */
243 if (ip6_maxfragpackets < 0)
244 ;
245 else if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets)
246 goto dropfrag;
247 frag6_nfragpackets++;
248 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
249 M_NOWAIT);
250 if (q6 == NULL)
251 goto dropfrag;
252 bzero(q6, sizeof(*q6));
253
254 frag6_insque(q6, &ip6q);
255
256 /* ip6q_nxt will be filled afterwards, from 1st fragment */
257 q6->ip6q_down = q6->ip6q_up = (struct ip6asfrag *)q6;
258 #ifdef notyet
259 q6->ip6q_nxtp = (u_char *)nxtp;
260 #endif
261 q6->ip6q_ident = ip6f->ip6f_ident;
262 q6->ip6q_ttl = IPV6_FRAGTTL;
263 q6->ip6q_src = ip6->ip6_src;
264 q6->ip6q_dst = ip6->ip6_dst;
265 q6->ip6q_ecn =
266 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
267 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
268
269 q6->ip6q_nfrag = 0;
270 }
271
272 /*
273 * If it's the 1st fragment, record the length of the
274 * unfragmentable part and the next header of the fragment header.
275 */
276 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
277 if (fragoff == 0) {
278 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
279 sizeof(struct ip6_frag);
280 q6->ip6q_nxt = ip6f->ip6f_nxt;
281 }
282
283 /*
284 * Check that the reassembled packet would not exceed 65535 bytes
285 * in size.
286 * If it would exceed, discard the fragment and return an ICMP error.
287 */
288 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
289 if (q6->ip6q_unfrglen >= 0) {
290 /* The 1st fragment has already arrived. */
291 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
292 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
293 offset - sizeof(struct ip6_frag) +
294 offsetof(struct ip6_frag, ip6f_offlg));
295 IP6Q_UNLOCK();
296 return (IPPROTO_DONE);
297 }
298 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
299 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
300 offset - sizeof(struct ip6_frag) +
301 offsetof(struct ip6_frag, ip6f_offlg));
302 IP6Q_UNLOCK();
303 return (IPPROTO_DONE);
304 }
305 /*
306 * If it's the first fragment, do the above check for each
307 * fragment already stored in the reassembly queue.
308 */
309 if (fragoff == 0) {
310 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
311 af6 = af6dwn) {
312 af6dwn = af6->ip6af_down;
313
314 if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
315 IPV6_MAXPACKET) {
316 struct mbuf *merr = IP6_REASS_MBUF(af6);
317 struct ip6_hdr *ip6err;
318 int erroff = af6->ip6af_offset;
319
320 /* dequeue the fragment. */
321 frag6_deq(af6);
322 free(af6, M_FTABLE);
323
324 /* adjust pointer. */
325 ip6err = mtod(merr, struct ip6_hdr *);
326
327 /*
328 * Restore source and destination addresses
329 * in the erroneous IPv6 header.
330 */
331 ip6err->ip6_src = q6->ip6q_src;
332 ip6err->ip6_dst = q6->ip6q_dst;
333
334 icmp6_error(merr, ICMP6_PARAM_PROB,
335 ICMP6_PARAMPROB_HEADER,
336 erroff - sizeof(struct ip6_frag) +
337 offsetof(struct ip6_frag, ip6f_offlg));
338 }
339 }
340 }
341
342 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
343 M_NOWAIT);
344 if (ip6af == NULL)
345 goto dropfrag;
346 bzero(ip6af, sizeof(*ip6af));
347 ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
348 ip6af->ip6af_off = fragoff;
349 ip6af->ip6af_frglen = frgpartlen;
350 ip6af->ip6af_offset = offset;
351 IP6_REASS_MBUF(ip6af) = m;
352
353 if (first_frag) {
354 af6 = (struct ip6asfrag *)q6;
355 goto insert;
356 }
357
358 /*
359 * Handle ECN by comparing this segment with the first one;
360 * if CE is set, do not lose CE.
361 * drop if CE and not-ECT are mixed for the same packet.
362 */
363 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
364 ecn0 = q6->ip6q_ecn;
365 if (ecn == IPTOS_ECN_CE) {
366 if (ecn0 == IPTOS_ECN_NOTECT) {
367 free(ip6af, M_FTABLE);
368 goto dropfrag;
369 }
370 if (ecn0 != IPTOS_ECN_CE)
371 q6->ip6q_ecn = IPTOS_ECN_CE;
372 }
373 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
374 free(ip6af, M_FTABLE);
375 goto dropfrag;
376 }
377
378 /*
379 * Find a segment which begins after this one does.
380 */
381 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
382 af6 = af6->ip6af_down)
383 if (af6->ip6af_off > ip6af->ip6af_off)
384 break;
385
386 #if 0
387 /*
388 * If there is a preceding segment, it may provide some of
389 * our data already. If so, drop the data from the incoming
390 * segment. If it provides all of our data, drop us.
391 */
392 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
393 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
394 - ip6af->ip6af_off;
395 if (i > 0) {
396 if (i >= ip6af->ip6af_frglen)
397 goto dropfrag;
398 m_adj(IP6_REASS_MBUF(ip6af), i);
399 ip6af->ip6af_off += i;
400 ip6af->ip6af_frglen -= i;
401 }
402 }
403
404 /*
405 * While we overlap succeeding segments trim them or,
406 * if they are completely covered, dequeue them.
407 */
408 while (af6 != (struct ip6asfrag *)q6 &&
409 ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
410 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
411 if (i < af6->ip6af_frglen) {
412 af6->ip6af_frglen -= i;
413 af6->ip6af_off += i;
414 m_adj(IP6_REASS_MBUF(af6), i);
415 break;
416 }
417 af6 = af6->ip6af_down;
418 m_freem(IP6_REASS_MBUF(af6->ip6af_up));
419 frag6_deq(af6->ip6af_up);
420 }
421 #else
422 /*
423 * If the incoming framgent overlaps some existing fragments in
424 * the reassembly queue, drop it, since it is dangerous to override
425 * existing fragments from a security point of view.
426 * We don't know which fragment is the bad guy - here we trust
427 * fragment that came in earlier, with no real reason.
428 *
429 * Note: due to changes after disabling this part, mbuf passed to
430 * m_adj() below now does not meet the requirement.
431 */
432 if (af6->ip6af_up != (struct ip6asfrag *)q6) {
433 i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
434 - ip6af->ip6af_off;
435 if (i > 0) {
436 #if 0 /* suppress the noisy log */
437 log(LOG_ERR, "%d bytes of a fragment from %s "
438 "overlaps the previous fragment\n",
439 i, ip6_sprintf(ip6buf, &q6->ip6q_src));
440 #endif
441 free(ip6af, M_FTABLE);
442 goto dropfrag;
443 }
444 }
445 if (af6 != (struct ip6asfrag *)q6) {
446 i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
447 if (i > 0) {
448 #if 0 /* suppress the noisy log */
449 log(LOG_ERR, "%d bytes of a fragment from %s "
450 "overlaps the succeeding fragment",
451 i, ip6_sprintf(ip6buf, &q6->ip6q_src));
452 #endif
453 free(ip6af, M_FTABLE);
454 goto dropfrag;
455 }
456 }
457 #endif
458
459 insert:
460
461 /*
462 * Stick new segment in its place;
463 * check for complete reassembly.
464 * Move to front of packet queue, as we are
465 * the most recently active fragmented packet.
466 */
467 frag6_enq(ip6af, af6->ip6af_up);
468 frag6_nfrags++;
469 q6->ip6q_nfrag++;
470 #if 0 /* xxx */
471 if (q6 != ip6q.ip6q_next) {
472 frag6_remque(q6);
473 frag6_insque(q6, &ip6q);
474 }
475 #endif
476 next = 0;
477 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
478 af6 = af6->ip6af_down) {
479 if (af6->ip6af_off != next) {
480 IP6Q_UNLOCK();
481 return IPPROTO_DONE;
482 }
483 next += af6->ip6af_frglen;
484 }
485 if (af6->ip6af_up->ip6af_mff) {
486 IP6Q_UNLOCK();
487 return IPPROTO_DONE;
488 }
489
490 /*
491 * Reassembly is complete; concatenate fragments.
492 */
493 ip6af = q6->ip6q_down;
494 t = m = IP6_REASS_MBUF(ip6af);
495 af6 = ip6af->ip6af_down;
496 frag6_deq(ip6af);
497 while (af6 != (struct ip6asfrag *)q6) {
498 af6dwn = af6->ip6af_down;
499 frag6_deq(af6);
500 while (t->m_next)
501 t = t->m_next;
502 t->m_next = IP6_REASS_MBUF(af6);
503 m_adj(t->m_next, af6->ip6af_offset);
504 free(af6, M_FTABLE);
505 af6 = af6dwn;
506 }
507
508 /* adjust offset to point where the original next header starts */
509 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
510 free(ip6af, M_FTABLE);
511 ip6 = mtod(m, struct ip6_hdr *);
512 ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
513 if (q6->ip6q_ecn == IPTOS_ECN_CE)
514 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
515 nxt = q6->ip6q_nxt;
516 #ifdef notyet
517 *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
518 #endif
519
520 /* Delete frag6 header */
521 if (m->m_len >= offset + sizeof(struct ip6_frag)) {
522 /* This is the only possible case with !PULLDOWN_TEST */
523 ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
524 offset);
525 m->m_data += sizeof(struct ip6_frag);
526 m->m_len -= sizeof(struct ip6_frag);
527 } else {
528 /* this comes with no copy if the boundary is on cluster */
529 if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
530 frag6_remque(q6);
531 frag6_nfrags -= q6->ip6q_nfrag;
532 free(q6, M_FTABLE);
533 frag6_nfragpackets--;
534 goto dropfrag;
535 }
536 m_adj(t, sizeof(struct ip6_frag));
537 m_cat(m, t);
538 }
539
540 /*
541 * Store NXT to the original.
542 */
543 {
544 char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
545 *prvnxtp = nxt;
546 }
547
548 frag6_remque(q6);
549 frag6_nfrags -= q6->ip6q_nfrag;
550 free(q6, M_FTABLE);
551 frag6_nfragpackets--;
552
553 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
554 int plen = 0;
555 for (t = m; t; t = t->m_next)
556 plen += t->m_len;
557 m->m_pkthdr.len = plen;
558 }
559
560 ip6stat.ip6s_reassembled++;
561 in6_ifstat_inc(dstifp, ifs6_reass_ok);
562
563 /*
564 * Tell launch routine the next header
565 */
566
567 *mp = m;
568 *offp = offset;
569
570 IP6Q_UNLOCK();
571 return nxt;
572
573 dropfrag:
574 IP6Q_UNLOCK();
575 in6_ifstat_inc(dstifp, ifs6_reass_fail);
576 ip6stat.ip6s_fragdropped++;
577 m_freem(m);
578 return IPPROTO_DONE;
579 }
580
581 /*
582 * Free a fragment reassembly header and all
583 * associated datagrams.
584 */
585 void
586 frag6_freef(struct ip6q *q6)
587 {
588 struct ip6asfrag *af6, *down6;
589
590 IP6Q_LOCK_ASSERT();
591
592 for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
593 af6 = down6) {
594 struct mbuf *m = IP6_REASS_MBUF(af6);
595
596 down6 = af6->ip6af_down;
597 frag6_deq(af6);
598
599 /*
600 * Return ICMP time exceeded error for the 1st fragment.
601 * Just free other fragments.
602 */
603 if (af6->ip6af_off == 0) {
604 struct ip6_hdr *ip6;
605
606 /* adjust pointer */
607 ip6 = mtod(m, struct ip6_hdr *);
608
609 /* restore source and destination addresses */
610 ip6->ip6_src = q6->ip6q_src;
611 ip6->ip6_dst = q6->ip6q_dst;
612
613 icmp6_error(m, ICMP6_TIME_EXCEEDED,
614 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
615 } else
616 m_freem(m);
617 free(af6, M_FTABLE);
618 }
619 frag6_remque(q6);
620 frag6_nfrags -= q6->ip6q_nfrag;
621 free(q6, M_FTABLE);
622 frag6_nfragpackets--;
623 }
624
625 /*
626 * Put an ip fragment on a reassembly chain.
627 * Like insque, but pointers in middle of structure.
628 */
629 void
630 frag6_enq(struct ip6asfrag *af6, struct ip6asfrag *up6)
631 {
632
633 IP6Q_LOCK_ASSERT();
634
635 af6->ip6af_up = up6;
636 af6->ip6af_down = up6->ip6af_down;
637 up6->ip6af_down->ip6af_up = af6;
638 up6->ip6af_down = af6;
639 }
640
641 /*
642 * To frag6_enq as remque is to insque.
643 */
644 void
645 frag6_deq(struct ip6asfrag *af6)
646 {
647
648 IP6Q_LOCK_ASSERT();
649
650 af6->ip6af_up->ip6af_down = af6->ip6af_down;
651 af6->ip6af_down->ip6af_up = af6->ip6af_up;
652 }
653
654 void
655 frag6_insque(struct ip6q *new, struct ip6q *old)
656 {
657
658 IP6Q_LOCK_ASSERT();
659
660 new->ip6q_prev = old;
661 new->ip6q_next = old->ip6q_next;
662 old->ip6q_next->ip6q_prev= new;
663 old->ip6q_next = new;
664 }
665
666 void
667 frag6_remque(struct ip6q *p6)
668 {
669
670 IP6Q_LOCK_ASSERT();
671
672 p6->ip6q_prev->ip6q_next = p6->ip6q_next;
673 p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
674 }
675
676 /*
677 * IPv6 reassembling timer processing;
678 * if a timer expires on a reassembly
679 * queue, discard it.
680 */
681 void
682 frag6_slowtimo(void)
683 {
684 struct ip6q *q6;
685
686 #if 0
687 GIANT_REQUIRED; /* XXX bz: ip6_forward_rt */
688 #endif
689
690 IP6Q_LOCK();
691 q6 = ip6q.ip6q_next;
692 if (q6)
693 while (q6 != &ip6q) {
694 --q6->ip6q_ttl;
695 q6 = q6->ip6q_next;
696 if (q6->ip6q_prev->ip6q_ttl == 0) {
697 ip6stat.ip6s_fragtimeout++;
698 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
699 frag6_freef(q6->ip6q_prev);
700 }
701 }
702 /*
703 * If we are over the maximum number of fragments
704 * (due to the limit being lowered), drain off
705 * enough to get down to the new limit.
706 */
707 while (frag6_nfragpackets > (u_int)ip6_maxfragpackets &&
708 ip6q.ip6q_prev) {
709 ip6stat.ip6s_fragoverflow++;
710 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
711 frag6_freef(ip6q.ip6q_prev);
712 }
713 IP6Q_UNLOCK();
714
715 #if 0
716 /*
717 * Routing changes might produce a better route than we last used;
718 * make sure we notice eventually, even if forwarding only for one
719 * destination and the cache is never replaced.
720 */
721 if (ip6_forward_rt.ro_rt) {
722 RTFREE(ip6_forward_rt.ro_rt);
723 ip6_forward_rt.ro_rt = 0;
724 }
725 if (ipsrcchk_rt.ro_rt) {
726 RTFREE(ipsrcchk_rt.ro_rt);
727 ipsrcchk_rt.ro_rt = 0;
728 }
729 #endif
730 }
731
732 /*
733 * Drain off all datagram fragments.
734 */
735 void
736 frag6_drain(void)
737 {
738
739 if (IP6Q_TRYLOCK() == 0)
740 return;
741 while (ip6q.ip6q_next != &ip6q) {
742 ip6stat.ip6s_fragdropped++;
743 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
744 frag6_freef(ip6q.ip6q_next);
745 }
746 IP6Q_UNLOCK();
747 }
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