3 * This is the IPv4 packet segmentation and reassembly implementation.
8 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
11 * Redistribution and use in source and binary forms, with or without modification,
12 * are permitted provided that the following conditions are met:
14 * 1. Redistributions of source code must retain the above copyright notice,
15 * this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright notice,
17 * this list of conditions and the following disclaimer in the documentation
18 * and/or other materials provided with the distribution.
19 * 3. The name of the author may not be used to endorse or promote products
20 * derived from this software without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
23 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
24 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
25 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
26 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
27 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
30 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
33 * This file is part of the lwIP TCP/IP stack.
35 * Author: Jani Monoses <jani@iv.ro>
37 * original reassembly code by Adam Dunkels <adam@sics.se>
45 #include "lwip/ip4_frag.h"
47 #include "lwip/inet_chksum.h"
48 #include "lwip/netif.h"
49 #include "lwip/stats.h"
50 #include "lwip/icmp.h"
56 * The IP reassembly code currently has the following limitations:
57 * - IP header options are not supported
58 * - fragments must not overlap (e.g. due to different routes),
59 * currently, overlapping or duplicate fragments are thrown away
60 * if IP_REASS_CHECK_OVERLAP=1 (the default)!
62 * @todo: work with IP header options
65 /** Setting this to 0, you can turn off checking the fragments for overlapping
66 * regions. The code gets a little smaller. Only use this if you know that
67 * overlapping won't occur on your network! */
68 #ifndef IP_REASS_CHECK_OVERLAP
69 #define IP_REASS_CHECK_OVERLAP 1
70 #endif /* IP_REASS_CHECK_OVERLAP */
72 /** Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is
73 * full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller.
74 * Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA
75 * is set to 1, so one datagram can be reassembled at a time, only. */
76 #ifndef IP_REASS_FREE_OLDEST
77 #define IP_REASS_FREE_OLDEST 1
78 #endif /* IP_REASS_FREE_OLDEST */
80 #define IP_REASS_FLAG_LASTFRAG 0x01
82 #define IP_REASS_VALIDATE_TELEGRAM_FINISHED 1
83 #define IP_REASS_VALIDATE_PBUF_QUEUED 0
84 #define IP_REASS_VALIDATE_PBUF_DROPPED -1
86 /** This is a helper struct which holds the starting
87 * offset and the ending offset of this fragment to
88 * easily chain the fragments.
89 * It has the same packing requirements as the IP header, since it replaces
90 * the IP header in memory in incoming fragments (after copying it) to keep
91 * track of the various fragments. (-> If the IP header doesn't need packing,
92 * this struct doesn't need packing, too.)
94 #ifdef PACK_STRUCT_USE_INCLUDES
95 # include "arch/bpstruct.h"
98 struct ip_reass_helper {
99 PACK_STRUCT_FIELD(struct pbuf *next_pbuf);
100 PACK_STRUCT_FIELD(u16_t start);
101 PACK_STRUCT_FIELD(u16_t end);
102 } PACK_STRUCT_STRUCT;
104 #ifdef PACK_STRUCT_USE_INCLUDES
105 # include "arch/epstruct.h"
108 #define IP_ADDRESSES_AND_ID_MATCH(iphdrA, iphdrB) \
109 (ip4_addr_cmp(&(iphdrA)->src, &(iphdrB)->src) && \
110 ip4_addr_cmp(&(iphdrA)->dest, &(iphdrB)->dest) && \
111 IPH_ID(iphdrA) == IPH_ID(iphdrB)) ? 1 : 0
113 /* global variables */
114 static struct ip_reassdata *reassdatagrams;
115 static u16_t ip_reass_pbufcount;
117 /* function prototypes */
118 static void ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev);
119 static int ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev);
122 * Reassembly timer base function
123 * for both NO_SYS == 0 and 1 (!).
125 * Should be called every 1000 msec (defined by IP_TMR_INTERVAL).
130 struct ip_reassdata *r, *prev = NULL;
134 /* Decrement the timer. Once it reaches 0,
135 * clean up the incomplete fragment assembly */
138 LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer dec %"U16_F"\n",(u16_t)r->timer));
142 /* reassembly timed out */
143 struct ip_reassdata *tmp;
144 LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer timed out\n"));
146 /* get the next pointer before freeing */
148 /* free the helper struct and all enqueued pbufs */
149 ip_reass_free_complete_datagram(tmp, prev);
155 * Free a datagram (struct ip_reassdata) and all its pbufs.
156 * Updates the total count of enqueued pbufs (ip_reass_pbufcount),
157 * SNMP counters and sends an ICMP time exceeded packet.
159 * @param ipr datagram to free
160 * @param prev the previous datagram in the linked list
161 * @return the number of pbufs freed
164 ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev)
166 u16_t pbufs_freed = 0;
169 struct ip_reass_helper *iprh;
171 LWIP_ASSERT("prev != ipr", prev != ipr);
173 LWIP_ASSERT("prev->next == ipr", prev->next == ipr);
176 MIB2_STATS_INC(mib2.ipreasmfails);
178 iprh = (struct ip_reass_helper *)ipr->p->payload;
179 if (iprh->start == 0) {
180 /* The first fragment was received, send ICMP time exceeded. */
181 /* First, de-queue the first pbuf from r->p. */
183 ipr->p = iprh->next_pbuf;
184 /* Then, copy the original header into it. */
185 SMEMCPY(p->payload, &ipr->iphdr, IP_HLEN);
186 icmp_time_exceeded(p, ICMP_TE_FRAG);
188 LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
192 #endif /* LWIP_ICMP */
194 /* First, free all received pbufs. The individual pbufs need to be released
195 separately as they have not yet been chained */
199 iprh = (struct ip_reass_helper *)p->payload;
201 /* get the next pointer before freeing */
203 clen = pbuf_clen(pcur);
204 LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
208 /* Then, unchain the struct ip_reassdata from the list and free it. */
209 ip_reass_dequeue_datagram(ipr, prev);
210 LWIP_ASSERT("ip_reass_pbufcount >= clen", ip_reass_pbufcount >= pbufs_freed);
211 ip_reass_pbufcount -= pbufs_freed;
216 #if IP_REASS_FREE_OLDEST
218 * Free the oldest datagram to make room for enqueueing new fragments.
219 * The datagram 'fraghdr' belongs to is not freed!
221 * @param fraghdr IP header of the current fragment
222 * @param pbufs_needed number of pbufs needed to enqueue
223 * (used for freeing other datagrams if not enough space)
224 * @return the number of pbufs freed
227 ip_reass_remove_oldest_datagram(struct ip_hdr *fraghdr, int pbufs_needed)
229 /* @todo Can't we simply remove the last datagram in the
230 * linked list behind reassdatagrams?
232 struct ip_reassdata *r, *oldest, *prev, *oldest_prev;
233 int pbufs_freed = 0, pbufs_freed_current;
236 /* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs,
237 * but don't free the datagram that 'fraghdr' belongs to! */
245 if (!IP_ADDRESSES_AND_ID_MATCH(&r->iphdr, fraghdr)) {
246 /* Not the same datagram as fraghdr */
248 if (oldest == NULL) {
251 } else if (r->timer <= oldest->timer) {
252 /* older than the previous oldest */
257 if (r->next != NULL) {
262 if (oldest != NULL) {
263 pbufs_freed_current = ip_reass_free_complete_datagram(oldest, oldest_prev);
264 pbufs_freed += pbufs_freed_current;
266 } while ((pbufs_freed < pbufs_needed) && (other_datagrams > 1));
269 #endif /* IP_REASS_FREE_OLDEST */
272 * Enqueues a new fragment into the fragment queue
273 * @param fraghdr points to the new fragments IP hdr
274 * @param clen number of pbufs needed to enqueue (used for freeing other datagrams if not enough space)
275 * @return A pointer to the queue location into which the fragment was enqueued
277 static struct ip_reassdata*
278 ip_reass_enqueue_new_datagram(struct ip_hdr *fraghdr, int clen)
280 struct ip_reassdata* ipr;
281 #if ! IP_REASS_FREE_OLDEST
282 LWIP_UNUSED_ARG(clen);
285 /* No matching previous fragment found, allocate a new reassdata struct */
286 ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
288 #if IP_REASS_FREE_OLDEST
289 if (ip_reass_remove_oldest_datagram(fraghdr, clen) >= clen) {
290 ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
293 #endif /* IP_REASS_FREE_OLDEST */
295 IPFRAG_STATS_INC(ip_frag.memerr);
296 LWIP_DEBUGF(IP_REASS_DEBUG,("Failed to alloc reassdata struct\n"));
300 memset(ipr, 0, sizeof(struct ip_reassdata));
301 ipr->timer = IP_REASS_MAXAGE;
303 /* enqueue the new structure to the front of the list */
304 ipr->next = reassdatagrams;
305 reassdatagrams = ipr;
306 /* copy the ip header for later tests and input */
307 /* @todo: no ip options supported? */
308 SMEMCPY(&(ipr->iphdr), fraghdr, IP_HLEN);
313 * Dequeues a datagram from the datagram queue. Doesn't deallocate the pbufs.
314 * @param ipr points to the queue entry to dequeue
317 ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev)
319 /* dequeue the reass struct */
320 if (reassdatagrams == ipr) {
321 /* it was the first in the list */
322 reassdatagrams = ipr->next;
324 /* it wasn't the first, so it must have a valid 'prev' */
325 LWIP_ASSERT("sanity check linked list", prev != NULL);
326 prev->next = ipr->next;
329 /* now we can free the ip_reassdata struct */
330 memp_free(MEMP_REASSDATA, ipr);
334 * Chain a new pbuf into the pbuf list that composes the datagram. The pbuf list
335 * will grow over time as new pbufs are rx.
336 * Also checks that the datagram passes basic continuity checks (if the last
337 * fragment was received at least once).
338 * @param ipr points to the reassembly state
339 * @param new_p points to the pbuf for the current fragment
340 * @param is_last is 1 if this pbuf has MF==0 (ipr->flags not updated yet)
341 * @return see IP_REASS_VALIDATE_* defines
344 ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct pbuf *new_p, int is_last)
346 struct ip_reass_helper *iprh, *iprh_tmp, *iprh_prev=NULL;
349 struct ip_hdr *fraghdr;
352 /* Extract length and fragment offset from current fragment */
353 fraghdr = (struct ip_hdr*)new_p->payload;
354 len = lwip_ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4;
355 offset = (lwip_ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8;
357 /* overwrite the fragment's ip header from the pbuf with our helper struct,
358 * and setup the embedded helper structure. */
359 /* make sure the struct ip_reass_helper fits into the IP header */
360 LWIP_ASSERT("sizeof(struct ip_reass_helper) <= IP_HLEN",
361 sizeof(struct ip_reass_helper) <= IP_HLEN);
362 iprh = (struct ip_reass_helper*)new_p->payload;
363 iprh->next_pbuf = NULL;
364 iprh->start = offset;
365 iprh->end = offset + len;
367 /* Iterate through until we either get to the end of the list (append),
368 * or we find one with a larger offset (insert). */
369 for (q = ipr->p; q != NULL;) {
370 iprh_tmp = (struct ip_reass_helper*)q->payload;
371 if (iprh->start < iprh_tmp->start) {
372 /* the new pbuf should be inserted before this */
374 if (iprh_prev != NULL) {
375 /* not the fragment with the lowest offset */
376 #if IP_REASS_CHECK_OVERLAP
377 if ((iprh->start < iprh_prev->end) || (iprh->end > iprh_tmp->start)) {
378 /* fragment overlaps with previous or following, throw away */
381 #endif /* IP_REASS_CHECK_OVERLAP */
382 iprh_prev->next_pbuf = new_p;
383 if (iprh_prev->end != iprh->start) {
384 /* There is a fragment missing between the current
385 * and the previous fragment */
389 #if IP_REASS_CHECK_OVERLAP
390 if (iprh->end > iprh_tmp->start) {
391 /* fragment overlaps with following, throw away */
394 #endif /* IP_REASS_CHECK_OVERLAP */
395 /* fragment with the lowest offset */
399 } else if (iprh->start == iprh_tmp->start) {
400 /* received the same datagram twice: no need to keep the datagram */
402 #if IP_REASS_CHECK_OVERLAP
403 } else if (iprh->start < iprh_tmp->end) {
404 /* overlap: no need to keep the new datagram */
406 #endif /* IP_REASS_CHECK_OVERLAP */
408 /* Check if the fragments received so far have no holes. */
409 if (iprh_prev != NULL) {
410 if (iprh_prev->end != iprh_tmp->start) {
411 /* There is a fragment missing between the current
412 * and the previous fragment */
417 q = iprh_tmp->next_pbuf;
418 iprh_prev = iprh_tmp;
421 /* If q is NULL, then we made it to the end of the list. Determine what to do now */
423 if (iprh_prev != NULL) {
424 /* this is (for now), the fragment with the highest offset:
425 * chain it to the last fragment */
426 #if IP_REASS_CHECK_OVERLAP
427 LWIP_ASSERT("check fragments don't overlap", iprh_prev->end <= iprh->start);
428 #endif /* IP_REASS_CHECK_OVERLAP */
429 iprh_prev->next_pbuf = new_p;
430 if (iprh_prev->end != iprh->start) {
434 #if IP_REASS_CHECK_OVERLAP
435 LWIP_ASSERT("no previous fragment, this must be the first fragment!",
437 #endif /* IP_REASS_CHECK_OVERLAP */
438 /* this is the first fragment we ever received for this ip datagram */
443 /* At this point, the validation part begins: */
444 /* If we already received the last fragment */
445 if (is_last || ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0)) {
446 /* and had no holes so far */
448 /* then check if the rest of the fragments is here */
449 /* Check if the queue starts with the first datagram */
450 if ((ipr->p == NULL) || (((struct ip_reass_helper*)ipr->p->payload)->start != 0)) {
453 /* and check that there are no holes after this datagram */
457 iprh = (struct ip_reass_helper*)q->payload;
458 if (iprh_prev->end != iprh->start) {
465 /* if still valid, all fragments are received
466 * (because to the MF==0 already arrived */
468 LWIP_ASSERT("sanity check", ipr->p != NULL);
469 LWIP_ASSERT("sanity check",
470 ((struct ip_reass_helper*)ipr->p->payload) != iprh);
471 LWIP_ASSERT("validate_datagram:next_pbuf!=NULL",
472 iprh->next_pbuf == NULL);
476 /* If valid is 0 here, there are some fragments missing in the middle
477 * (since MF == 0 has already arrived). Such datagrams simply time out if
478 * no more fragments are received... */
479 return valid ? IP_REASS_VALIDATE_TELEGRAM_FINISHED : IP_REASS_VALIDATE_PBUF_QUEUED;
481 /* If we come here, not all fragments were received, yet! */
482 return IP_REASS_VALIDATE_PBUF_QUEUED; /* not yet valid! */
483 #if IP_REASS_CHECK_OVERLAP
485 ip_reass_pbufcount -= pbuf_clen(new_p);
487 return IP_REASS_VALIDATE_PBUF_DROPPED;
488 #endif /* IP_REASS_CHECK_OVERLAP */
492 * Reassembles incoming IP fragments into an IP datagram.
494 * @param p points to a pbuf chain of the fragment
495 * @return NULL if reassembly is incomplete, ? otherwise
498 ip4_reass(struct pbuf *p)
501 struct ip_hdr *fraghdr;
502 struct ip_reassdata *ipr;
503 struct ip_reass_helper *iprh;
504 u16_t offset, len, clen;
508 IPFRAG_STATS_INC(ip_frag.recv);
509 MIB2_STATS_INC(mib2.ipreasmreqds);
511 fraghdr = (struct ip_hdr*)p->payload;
513 if ((IPH_HL(fraghdr) * 4) != IP_HLEN) {
514 LWIP_DEBUGF(IP_REASS_DEBUG,("ip4_reass: IP options currently not supported!\n"));
515 IPFRAG_STATS_INC(ip_frag.err);
519 offset = (lwip_ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8;
520 len = lwip_ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4;
522 /* Check if we are allowed to enqueue more datagrams. */
524 if ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS) {
525 #if IP_REASS_FREE_OLDEST
526 if (!ip_reass_remove_oldest_datagram(fraghdr, clen) ||
527 ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS))
528 #endif /* IP_REASS_FREE_OLDEST */
530 /* No datagram could be freed and still too many pbufs enqueued */
531 LWIP_DEBUGF(IP_REASS_DEBUG,("ip4_reass: Overflow condition: pbufct=%d, clen=%d, MAX=%d\n",
532 ip_reass_pbufcount, clen, IP_REASS_MAX_PBUFS));
533 IPFRAG_STATS_INC(ip_frag.memerr);
534 /* @todo: send ICMP time exceeded here? */
540 /* Look for the datagram the fragment belongs to in the current datagram queue,
541 * remembering the previous in the queue for later dequeueing. */
542 for (ipr = reassdatagrams; ipr != NULL; ipr = ipr->next) {
543 /* Check if the incoming fragment matches the one currently present
544 in the reassembly buffer. If so, we proceed with copying the
545 fragment into the buffer. */
546 if (IP_ADDRESSES_AND_ID_MATCH(&ipr->iphdr, fraghdr)) {
547 LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: matching previous fragment ID=%"X16_F"\n",
548 lwip_ntohs(IPH_ID(fraghdr))));
549 IPFRAG_STATS_INC(ip_frag.cachehit);
555 /* Enqueue a new datagram into the datagram queue */
556 ipr = ip_reass_enqueue_new_datagram(fraghdr, clen);
557 /* Bail if unable to enqueue */
562 if (((lwip_ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) == 0) &&
563 ((lwip_ntohs(IPH_OFFSET(&ipr->iphdr)) & IP_OFFMASK) != 0)) {
564 /* ipr->iphdr is not the header from the first fragment, but fraghdr is
565 * -> copy fraghdr into ipr->iphdr since we want to have the header
566 * of the first fragment (for ICMP time exceeded and later, for copying
567 * all options, if supported)*/
568 SMEMCPY(&ipr->iphdr, fraghdr, IP_HLEN);
572 /* At this point, we have either created a new entry or pointing
573 * to an existing one */
575 /* check for 'no more fragments', and update queue entry*/
576 is_last = (IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0;
578 u16_t datagram_len = (u16_t)(offset + len);
579 if ((datagram_len < offset) || (datagram_len > (0xFFFF - IP_HLEN))) {
580 /* u16_t overflow, cannot handle this */
584 /* find the right place to insert this pbuf */
585 /* @todo: trim pbufs if fragments are overlapping */
586 valid = ip_reass_chain_frag_into_datagram_and_validate(ipr, p, is_last);
587 if (valid == IP_REASS_VALIDATE_PBUF_DROPPED) {
590 /* if we come here, the pbuf has been enqueued */
592 /* Track the current number of pbufs current 'in-flight', in order to limit
593 the number of fragments that may be enqueued at any one time
594 (overflow checked by testing against IP_REASS_MAX_PBUFS) */
595 ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount + clen);
597 u16_t datagram_len = (u16_t)(offset + len);
598 ipr->datagram_len = datagram_len;
599 ipr->flags |= IP_REASS_FLAG_LASTFRAG;
600 LWIP_DEBUGF(IP_REASS_DEBUG,
601 ("ip4_reass: last fragment seen, total len %"S16_F"\n",
605 if (valid == IP_REASS_VALIDATE_TELEGRAM_FINISHED) {
606 struct ip_reassdata *ipr_prev;
607 /* the totally last fragment (flag more fragments = 0) was received at least
608 * once AND all fragments are received */
609 ipr->datagram_len += IP_HLEN;
611 /* save the second pbuf before copying the header over the pointer */
612 r = ((struct ip_reass_helper*)ipr->p->payload)->next_pbuf;
614 /* copy the original ip header back to the first pbuf */
615 fraghdr = (struct ip_hdr*)(ipr->p->payload);
616 SMEMCPY(fraghdr, &ipr->iphdr, IP_HLEN);
617 IPH_LEN_SET(fraghdr, lwip_htons(ipr->datagram_len));
618 IPH_OFFSET_SET(fraghdr, 0);
619 IPH_CHKSUM_SET(fraghdr, 0);
620 /* @todo: do we need to set/calculate the correct checksum? */
622 IF__NETIF_CHECKSUM_ENABLED(ip_current_input_netif(), NETIF_CHECKSUM_GEN_IP) {
623 IPH_CHKSUM_SET(fraghdr, inet_chksum(fraghdr, IP_HLEN));
625 #endif /* CHECKSUM_GEN_IP */
629 /* chain together the pbufs contained within the reass_data list. */
631 iprh = (struct ip_reass_helper*)r->payload;
633 /* hide the ip header for every succeeding fragment */
634 pbuf_header(r, -IP_HLEN);
639 /* find the previous entry in the linked list */
640 if (ipr == reassdatagrams) {
643 for (ipr_prev = reassdatagrams; ipr_prev != NULL; ipr_prev = ipr_prev->next) {
644 if (ipr_prev->next == ipr) {
650 /* release the sources allocate for the fragment queue entry */
651 ip_reass_dequeue_datagram(ipr, ipr_prev);
653 /* and adjust the number of pbufs currently queued for reassembly. */
654 ip_reass_pbufcount -= pbuf_clen(p);
656 MIB2_STATS_INC(mib2.ipreasmoks);
658 /* Return the pbuf chain */
661 /* the datagram is not (yet?) reassembled completely */
662 LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass_pbufcount: %d out\n", ip_reass_pbufcount));
666 LWIP_DEBUGF(IP_REASS_DEBUG,("ip4_reass: nullreturn\n"));
667 IPFRAG_STATS_INC(ip_frag.drop);
671 #endif /* IP_REASSEMBLY */
674 #if !LWIP_NETIF_TX_SINGLE_PBUF
675 /** Allocate a new struct pbuf_custom_ref */
676 static struct pbuf_custom_ref*
677 ip_frag_alloc_pbuf_custom_ref(void)
679 return (struct pbuf_custom_ref*)memp_malloc(MEMP_FRAG_PBUF);
682 /** Free a struct pbuf_custom_ref */
684 ip_frag_free_pbuf_custom_ref(struct pbuf_custom_ref* p)
686 LWIP_ASSERT("p != NULL", p != NULL);
687 memp_free(MEMP_FRAG_PBUF, p);
690 /** Free-callback function to free a 'struct pbuf_custom_ref', called by
693 ipfrag_free_pbuf_custom(struct pbuf *p)
695 struct pbuf_custom_ref *pcr = (struct pbuf_custom_ref*)p;
696 LWIP_ASSERT("pcr != NULL", pcr != NULL);
697 LWIP_ASSERT("pcr == p", (void*)pcr == (void*)p);
698 if (pcr->original != NULL) {
699 pbuf_free(pcr->original);
701 ip_frag_free_pbuf_custom_ref(pcr);
703 #endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
706 * Fragment an IP datagram if too large for the netif.
708 * Chop the datagram in MTU sized chunks and send them in order
709 * by pointing PBUF_REFs into p.
711 * @param p ip packet to send
712 * @param netif the netif on which to send
713 * @param dest destination ip address to which to send
715 * @return ERR_OK if sent successfully, err_t otherwise
718 ip4_frag(struct pbuf *p, struct netif *netif, const ip4_addr_t *dest)
721 #if !LWIP_NETIF_TX_SINGLE_PBUF
722 struct pbuf *newpbuf;
723 u16_t newpbuflen = 0;
726 struct ip_hdr *original_iphdr;
727 struct ip_hdr *iphdr;
728 const u16_t nfb = (netif->mtu - IP_HLEN) / 8;
729 u16_t left, fragsize;
732 u16_t poff = IP_HLEN;
735 original_iphdr = (struct ip_hdr *)p->payload;
736 iphdr = original_iphdr;
737 LWIP_ERROR("ip4_frag() does not support IP options", IPH_HL(iphdr) * 4 == IP_HLEN, return ERR_VAL);
739 /* Save original offset */
740 tmp = lwip_ntohs(IPH_OFFSET(iphdr));
741 ofo = tmp & IP_OFFMASK;
742 LWIP_ERROR("ip_frag(): MF already set", (tmp & IP_MF) == 0, return ERR_VAL);
744 left = p->tot_len - IP_HLEN;
747 /* Fill this fragment */
748 fragsize = LWIP_MIN(left, nfb * 8);
750 #if LWIP_NETIF_TX_SINGLE_PBUF
751 rambuf = pbuf_alloc(PBUF_IP, fragsize, PBUF_RAM);
752 if (rambuf == NULL) {
755 LWIP_ASSERT("this needs a pbuf in one piece!",
756 (rambuf->len == rambuf->tot_len) && (rambuf->next == NULL));
757 poff += pbuf_copy_partial(p, rambuf->payload, fragsize, poff);
758 /* make room for the IP header */
759 if (pbuf_header(rambuf, IP_HLEN)) {
763 /* fill in the IP header */
764 SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
765 iphdr = (struct ip_hdr*)rambuf->payload;
766 #else /* LWIP_NETIF_TX_SINGLE_PBUF */
767 /* When not using a static buffer, create a chain of pbufs.
768 * The first will be a PBUF_RAM holding the link and IP header.
769 * The rest will be PBUF_REFs mirroring the pbuf chain to be fragged,
770 * but limited to the size of an mtu.
772 rambuf = pbuf_alloc(PBUF_LINK, IP_HLEN, PBUF_RAM);
773 if (rambuf == NULL) {
776 LWIP_ASSERT("this needs a pbuf in one piece!",
777 (p->len >= (IP_HLEN)));
778 SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
779 iphdr = (struct ip_hdr *)rambuf->payload;
781 left_to_copy = fragsize;
782 while (left_to_copy) {
783 struct pbuf_custom_ref *pcr;
784 u16_t plen = p->len - poff;
785 newpbuflen = LWIP_MIN(left_to_copy, plen);
786 /* Is this pbuf already empty? */
792 pcr = ip_frag_alloc_pbuf_custom_ref();
797 /* Mirror this pbuf, although we might not need all of it. */
798 newpbuf = pbuf_alloced_custom(PBUF_RAW, newpbuflen, PBUF_REF, &pcr->pc,
799 (u8_t*)p->payload + poff, newpbuflen);
800 if (newpbuf == NULL) {
801 ip_frag_free_pbuf_custom_ref(pcr);
807 pcr->pc.custom_free_function = ipfrag_free_pbuf_custom;
809 /* Add it to end of rambuf's chain, but using pbuf_cat, not pbuf_chain
810 * so that it is removed when pbuf_dechain is later called on rambuf.
812 pbuf_cat(rambuf, newpbuf);
813 left_to_copy -= newpbuflen;
820 #endif /* LWIP_NETIF_TX_SINGLE_PBUF */
823 last = (left <= netif->mtu - IP_HLEN);
825 /* Set new offset and MF flag */
826 tmp = (IP_OFFMASK & (ofo));
830 IPH_OFFSET_SET(iphdr, lwip_htons(tmp));
831 IPH_LEN_SET(iphdr, lwip_htons(fragsize + IP_HLEN));
832 IPH_CHKSUM_SET(iphdr, 0);
834 IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) {
835 IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
837 #endif /* CHECKSUM_GEN_IP */
839 /* No need for separate header pbuf - we allowed room for it in rambuf
842 netif->output(netif, rambuf, dest);
843 IPFRAG_STATS_INC(ip_frag.xmit);
845 /* Unfortunately we can't reuse rambuf - the hardware may still be
846 * using the buffer. Instead we free it (and the ensuing chain) and
847 * recreate it next time round the loop. If we're lucky the hardware
848 * will have already sent the packet, the free will really free, and
849 * there will be zero memory penalty.
856 MIB2_STATS_INC(mib2.ipfragoks);
859 MIB2_STATS_INC(mib2.ipfragfails);
864 #endif /* LWIP_IPV4 */