diff options
Diffstat (limited to 'lwip/src/core/ipv4/ip4_frag.c')
| -rw-r--r-- | lwip/src/core/ipv4/ip4_frag.c | 894 |
1 files changed, 894 insertions, 0 deletions
diff --git a/lwip/src/core/ipv4/ip4_frag.c b/lwip/src/core/ipv4/ip4_frag.c new file mode 100644 index 0000000..a445530 --- /dev/null +++ b/lwip/src/core/ipv4/ip4_frag.c @@ -0,0 +1,894 @@ +/** + * @file + * This is the IPv4 packet segmentation and reassembly implementation. + * + */ + +/* + * Copyright (c) 2001-2004 Swedish Institute of Computer Science. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without modification, + * are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT + * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT + * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING + * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY + * OF SUCH DAMAGE. + * + * This file is part of the lwIP TCP/IP stack. + * + * Author: Jani Monoses <jani@iv.ro> + * Simon Goldschmidt + * original reassembly code by Adam Dunkels <adam@sics.se> + * + */ + +#include "lwip/opt.h" + +#if LWIP_IPV4 + +#include "lwip/ip4_frag.h" +#include "lwip/def.h" +#include "lwip/inet_chksum.h" +#include "lwip/netif.h" +#include "lwip/stats.h" +#include "lwip/icmp.h" + +#include <string.h> + +#if IP_REASSEMBLY +/** + * The IP reassembly code currently has the following limitations: + * - IP header options are not supported + * - fragments must not overlap (e.g. due to different routes), + * currently, overlapping or duplicate fragments are thrown away + * if IP_REASS_CHECK_OVERLAP=1 (the default)! + * + * @todo: work with IP header options + */ + +/** Setting this to 0, you can turn off checking the fragments for overlapping + * regions. The code gets a little smaller. Only use this if you know that + * overlapping won't occur on your network! */ +#ifndef IP_REASS_CHECK_OVERLAP +#define IP_REASS_CHECK_OVERLAP 1 +#endif /* IP_REASS_CHECK_OVERLAP */ + +/** Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is + * full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller. + * Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA + * is set to 1, so one datagram can be reassembled at a time, only. */ +#ifndef IP_REASS_FREE_OLDEST +#define IP_REASS_FREE_OLDEST 1 +#endif /* IP_REASS_FREE_OLDEST */ + +#define IP_REASS_FLAG_LASTFRAG 0x01 + +#define IP_REASS_VALIDATE_TELEGRAM_FINISHED 1 +#define IP_REASS_VALIDATE_PBUF_QUEUED 0 +#define IP_REASS_VALIDATE_PBUF_DROPPED -1 + +/** This is a helper struct which holds the starting + * offset and the ending offset of this fragment to + * easily chain the fragments. + * It has the same packing requirements as the IP header, since it replaces + * the IP header in memory in incoming fragments (after copying it) to keep + * track of the various fragments. (-> If the IP header doesn't need packing, + * this struct doesn't need packing, too.) + */ +#ifdef PACK_STRUCT_USE_INCLUDES +# include "arch/bpstruct.h" +#endif +PACK_STRUCT_BEGIN +struct ip_reass_helper { + PACK_STRUCT_FIELD(struct pbuf *next_pbuf); + PACK_STRUCT_FIELD(u16_t start); + PACK_STRUCT_FIELD(u16_t end); +} PACK_STRUCT_STRUCT; +PACK_STRUCT_END +#ifdef PACK_STRUCT_USE_INCLUDES +# include "arch/epstruct.h" +#endif + +#define IP_ADDRESSES_AND_ID_MATCH(iphdrA, iphdrB) \ + (ip4_addr_cmp(&(iphdrA)->src, &(iphdrB)->src) && \ + ip4_addr_cmp(&(iphdrA)->dest, &(iphdrB)->dest) && \ + IPH_ID(iphdrA) == IPH_ID(iphdrB)) ? 1 : 0 + +/* global variables */ +static struct ip_reassdata *reassdatagrams; +static u16_t ip_reass_pbufcount; + +/* function prototypes */ +static void ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev); +static int ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev); + +/** + * Reassembly timer base function + * for both NO_SYS == 0 and 1 (!). + * + * Should be called every 1000 msec (defined by IP_TMR_INTERVAL). + */ +void +ip_reass_tmr(void) +{ + struct ip_reassdata *r, *prev = NULL; + + r = reassdatagrams; + while (r != NULL) { + /* Decrement the timer. Once it reaches 0, + * clean up the incomplete fragment assembly */ + if (r->timer > 0) { + r->timer--; + LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer dec %"U16_F"\n", (u16_t)r->timer)); + prev = r; + r = r->next; + } else { + /* reassembly timed out */ + struct ip_reassdata *tmp; + LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer timed out\n")); + tmp = r; + /* get the next pointer before freeing */ + r = r->next; + /* free the helper struct and all enqueued pbufs */ + ip_reass_free_complete_datagram(tmp, prev); + } + } +} + +/** + * Free a datagram (struct ip_reassdata) and all its pbufs. + * Updates the total count of enqueued pbufs (ip_reass_pbufcount), + * SNMP counters and sends an ICMP time exceeded packet. + * + * @param ipr datagram to free + * @param prev the previous datagram in the linked list + * @return the number of pbufs freed + */ +static int +ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev) +{ + u16_t pbufs_freed = 0; + u16_t clen; + struct pbuf *p; + struct ip_reass_helper *iprh; + + LWIP_ASSERT("prev != ipr", prev != ipr); + if (prev != NULL) { + LWIP_ASSERT("prev->next == ipr", prev->next == ipr); + } + + MIB2_STATS_INC(mib2.ipreasmfails); +#if LWIP_ICMP + iprh = (struct ip_reass_helper *)ipr->p->payload; + if (iprh->start == 0) { + /* The first fragment was received, send ICMP time exceeded. */ + /* First, de-queue the first pbuf from r->p. */ + p = ipr->p; + ipr->p = iprh->next_pbuf; + /* Then, copy the original header into it. */ + SMEMCPY(p->payload, &ipr->iphdr, IP_HLEN); + icmp_time_exceeded(p, ICMP_TE_FRAG); + clen = pbuf_clen(p); + LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff); + pbufs_freed = (u16_t)(pbufs_freed + clen); + pbuf_free(p); + } +#endif /* LWIP_ICMP */ + + /* First, free all received pbufs. The individual pbufs need to be released + separately as they have not yet been chained */ + p = ipr->p; + while (p != NULL) { + struct pbuf *pcur; + iprh = (struct ip_reass_helper *)p->payload; + pcur = p; + /* get the next pointer before freeing */ + p = iprh->next_pbuf; + clen = pbuf_clen(pcur); + LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff); + pbufs_freed = (u16_t)(pbufs_freed + clen); + pbuf_free(pcur); + } + /* Then, unchain the struct ip_reassdata from the list and free it. */ + ip_reass_dequeue_datagram(ipr, prev); + LWIP_ASSERT("ip_reass_pbufcount >= pbufs_freed", ip_reass_pbufcount >= pbufs_freed); + ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount - pbufs_freed); + + return pbufs_freed; +} + +#if IP_REASS_FREE_OLDEST +/** + * Free the oldest datagram to make room for enqueueing new fragments. + * The datagram 'fraghdr' belongs to is not freed! + * + * @param fraghdr IP header of the current fragment + * @param pbufs_needed number of pbufs needed to enqueue + * (used for freeing other datagrams if not enough space) + * @return the number of pbufs freed + */ +static int +ip_reass_remove_oldest_datagram(struct ip_hdr *fraghdr, int pbufs_needed) +{ + /* @todo Can't we simply remove the last datagram in the + * linked list behind reassdatagrams? + */ + struct ip_reassdata *r, *oldest, *prev, *oldest_prev; + int pbufs_freed = 0, pbufs_freed_current; + int other_datagrams; + + /* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs, + * but don't free the datagram that 'fraghdr' belongs to! */ + do { + oldest = NULL; + prev = NULL; + oldest_prev = NULL; + other_datagrams = 0; + r = reassdatagrams; + while (r != NULL) { + if (!IP_ADDRESSES_AND_ID_MATCH(&r->iphdr, fraghdr)) { + /* Not the same datagram as fraghdr */ + other_datagrams++; + if (oldest == NULL) { + oldest = r; + oldest_prev = prev; + } else if (r->timer <= oldest->timer) { + /* older than the previous oldest */ + oldest = r; + oldest_prev = prev; + } + } + if (r->next != NULL) { + prev = r; + } + r = r->next; + } + if (oldest != NULL) { + pbufs_freed_current = ip_reass_free_complete_datagram(oldest, oldest_prev); + pbufs_freed += pbufs_freed_current; + } + } while ((pbufs_freed < pbufs_needed) && (other_datagrams > 1)); + return pbufs_freed; +} +#endif /* IP_REASS_FREE_OLDEST */ + +/** + * Enqueues a new fragment into the fragment queue + * @param fraghdr points to the new fragments IP hdr + * @param clen number of pbufs needed to enqueue (used for freeing other datagrams if not enough space) + * @return A pointer to the queue location into which the fragment was enqueued + */ +static struct ip_reassdata * +ip_reass_enqueue_new_datagram(struct ip_hdr *fraghdr, int clen) +{ + struct ip_reassdata *ipr; +#if ! IP_REASS_FREE_OLDEST + LWIP_UNUSED_ARG(clen); +#endif + + /* No matching previous fragment found, allocate a new reassdata struct */ + ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA); + if (ipr == NULL) { +#if IP_REASS_FREE_OLDEST + if (ip_reass_remove_oldest_datagram(fraghdr, clen) >= clen) { + ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA); + } + if (ipr == NULL) +#endif /* IP_REASS_FREE_OLDEST */ + { + IPFRAG_STATS_INC(ip_frag.memerr); + LWIP_DEBUGF(IP_REASS_DEBUG, ("Failed to alloc reassdata struct\n")); + return NULL; + } + } + memset(ipr, 0, sizeof(struct ip_reassdata)); + ipr->timer = IP_REASS_MAXAGE; + + /* enqueue the new structure to the front of the list */ + ipr->next = reassdatagrams; + reassdatagrams = ipr; + /* copy the ip header for later tests and input */ + /* @todo: no ip options supported? */ + SMEMCPY(&(ipr->iphdr), fraghdr, IP_HLEN); + return ipr; +} + +/** + * Dequeues a datagram from the datagram queue. Doesn't deallocate the pbufs. + * @param ipr points to the queue entry to dequeue + */ +static void +ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev) +{ + /* dequeue the reass struct */ + if (reassdatagrams == ipr) { + /* it was the first in the list */ + reassdatagrams = ipr->next; + } else { + /* it wasn't the first, so it must have a valid 'prev' */ + LWIP_ASSERT("sanity check linked list", prev != NULL); + prev->next = ipr->next; + } + + /* now we can free the ip_reassdata struct */ + memp_free(MEMP_REASSDATA, ipr); +} + +/** + * Chain a new pbuf into the pbuf list that composes the datagram. The pbuf list + * will grow over time as new pbufs are rx. + * Also checks that the datagram passes basic continuity checks (if the last + * fragment was received at least once). + * @param ipr points to the reassembly state + * @param new_p points to the pbuf for the current fragment + * @param is_last is 1 if this pbuf has MF==0 (ipr->flags not updated yet) + * @return see IP_REASS_VALIDATE_* defines + */ +static int +ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct pbuf *new_p, int is_last) +{ + struct ip_reass_helper *iprh, *iprh_tmp, *iprh_prev = NULL; + struct pbuf *q; + u16_t offset, len; + u8_t hlen; + struct ip_hdr *fraghdr; + int valid = 1; + + /* Extract length and fragment offset from current fragment */ + fraghdr = (struct ip_hdr *)new_p->payload; + len = lwip_ntohs(IPH_LEN(fraghdr)); + hlen = IPH_HL_BYTES(fraghdr); + if (hlen > len) { + /* invalid datagram */ + return IP_REASS_VALIDATE_PBUF_DROPPED; + } + len = (u16_t)(len - hlen); + offset = IPH_OFFSET_BYTES(fraghdr); + + /* overwrite the fragment's ip header from the pbuf with our helper struct, + * and setup the embedded helper structure. */ + /* make sure the struct ip_reass_helper fits into the IP header */ + LWIP_ASSERT("sizeof(struct ip_reass_helper) <= IP_HLEN", + sizeof(struct ip_reass_helper) <= IP_HLEN); + iprh = (struct ip_reass_helper *)new_p->payload; + iprh->next_pbuf = NULL; + iprh->start = offset; + iprh->end = (u16_t)(offset + len); + if (iprh->end < offset) { + /* u16_t overflow, cannot handle this */ + return IP_REASS_VALIDATE_PBUF_DROPPED; + } + + /* Iterate through until we either get to the end of the list (append), + * or we find one with a larger offset (insert). */ + for (q = ipr->p; q != NULL;) { + iprh_tmp = (struct ip_reass_helper *)q->payload; + if (iprh->start < iprh_tmp->start) { + /* the new pbuf should be inserted before this */ + iprh->next_pbuf = q; + if (iprh_prev != NULL) { + /* not the fragment with the lowest offset */ +#if IP_REASS_CHECK_OVERLAP + if ((iprh->start < iprh_prev->end) || (iprh->end > iprh_tmp->start)) { + /* fragment overlaps with previous or following, throw away */ + return IP_REASS_VALIDATE_PBUF_DROPPED; + } +#endif /* IP_REASS_CHECK_OVERLAP */ + iprh_prev->next_pbuf = new_p; + if (iprh_prev->end != iprh->start) { + /* There is a fragment missing between the current + * and the previous fragment */ + valid = 0; + } + } else { +#if IP_REASS_CHECK_OVERLAP + if (iprh->end > iprh_tmp->start) { + /* fragment overlaps with following, throw away */ + return IP_REASS_VALIDATE_PBUF_DROPPED; + } +#endif /* IP_REASS_CHECK_OVERLAP */ + /* fragment with the lowest offset */ + ipr->p = new_p; + } + break; + } else if (iprh->start == iprh_tmp->start) { + /* received the same datagram twice: no need to keep the datagram */ + return IP_REASS_VALIDATE_PBUF_DROPPED; +#if IP_REASS_CHECK_OVERLAP + } else if (iprh->start < iprh_tmp->end) { + /* overlap: no need to keep the new datagram */ + return IP_REASS_VALIDATE_PBUF_DROPPED; +#endif /* IP_REASS_CHECK_OVERLAP */ + } else { + /* Check if the fragments received so far have no holes. */ + if (iprh_prev != NULL) { + if (iprh_prev->end != iprh_tmp->start) { + /* There is a fragment missing between the current + * and the previous fragment */ + valid = 0; + } + } + } + q = iprh_tmp->next_pbuf; + iprh_prev = iprh_tmp; + } + + /* If q is NULL, then we made it to the end of the list. Determine what to do now */ + if (q == NULL) { + if (iprh_prev != NULL) { + /* this is (for now), the fragment with the highest offset: + * chain it to the last fragment */ +#if IP_REASS_CHECK_OVERLAP + LWIP_ASSERT("check fragments don't overlap", iprh_prev->end <= iprh->start); +#endif /* IP_REASS_CHECK_OVERLAP */ + iprh_prev->next_pbuf = new_p; + if (iprh_prev->end != iprh->start) { + valid = 0; + } + } else { +#if IP_REASS_CHECK_OVERLAP + LWIP_ASSERT("no previous fragment, this must be the first fragment!", + ipr->p == NULL); +#endif /* IP_REASS_CHECK_OVERLAP */ + /* this is the first fragment we ever received for this ip datagram */ + ipr->p = new_p; + } + } + + /* At this point, the validation part begins: */ + /* If we already received the last fragment */ + if (is_last || ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0)) { + /* and had no holes so far */ + if (valid) { + /* then check if the rest of the fragments is here */ + /* Check if the queue starts with the first datagram */ + if ((ipr->p == NULL) || (((struct ip_reass_helper *)ipr->p->payload)->start != 0)) { + valid = 0; + } else { + /* and check that there are no holes after this datagram */ + iprh_prev = iprh; + q = iprh->next_pbuf; + while (q != NULL) { + iprh = (struct ip_reass_helper *)q->payload; + if (iprh_prev->end != iprh->start) { + valid = 0; + break; + } + iprh_prev = iprh; + q = iprh->next_pbuf; + } + /* if still valid, all fragments are received + * (because to the MF==0 already arrived */ + if (valid) { + LWIP_ASSERT("sanity check", ipr->p != NULL); + LWIP_ASSERT("sanity check", + ((struct ip_reass_helper *)ipr->p->payload) != iprh); + LWIP_ASSERT("validate_datagram:next_pbuf!=NULL", + iprh->next_pbuf == NULL); + } + } + } + /* If valid is 0 here, there are some fragments missing in the middle + * (since MF == 0 has already arrived). Such datagrams simply time out if + * no more fragments are received... */ + return valid ? IP_REASS_VALIDATE_TELEGRAM_FINISHED : IP_REASS_VALIDATE_PBUF_QUEUED; + } + /* If we come here, not all fragments were received, yet! */ + return IP_REASS_VALIDATE_PBUF_QUEUED; /* not yet valid! */ +} + +/** + * Reassembles incoming IP fragments into an IP datagram. + * + * @param p points to a pbuf chain of the fragment + * @return NULL if reassembly is incomplete, ? otherwise + */ +struct pbuf * +ip4_reass(struct pbuf *p) +{ + struct pbuf *r; + struct ip_hdr *fraghdr; + struct ip_reassdata *ipr; + struct ip_reass_helper *iprh; + u16_t offset, len, clen; + u8_t hlen; + int valid; + int is_last; + + IPFRAG_STATS_INC(ip_frag.recv); + MIB2_STATS_INC(mib2.ipreasmreqds); + + fraghdr = (struct ip_hdr *)p->payload; + + if (IPH_HL_BYTES(fraghdr) != IP_HLEN) { + LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: IP options currently not supported!\n")); + IPFRAG_STATS_INC(ip_frag.err); + goto nullreturn; + } + + offset = IPH_OFFSET_BYTES(fraghdr); + len = lwip_ntohs(IPH_LEN(fraghdr)); + hlen = IPH_HL_BYTES(fraghdr); + if (hlen > len) { + /* invalid datagram */ + goto nullreturn; + } + len = (u16_t)(len - hlen); + + /* Check if we are allowed to enqueue more datagrams. */ + clen = pbuf_clen(p); + if ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS) { +#if IP_REASS_FREE_OLDEST + if (!ip_reass_remove_oldest_datagram(fraghdr, clen) || + ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS)) +#endif /* IP_REASS_FREE_OLDEST */ + { + /* No datagram could be freed and still too many pbufs enqueued */ + LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: Overflow condition: pbufct=%d, clen=%d, MAX=%d\n", + ip_reass_pbufcount, clen, IP_REASS_MAX_PBUFS)); + IPFRAG_STATS_INC(ip_frag.memerr); + /* @todo: send ICMP time exceeded here? */ + /* drop this pbuf */ + goto nullreturn; + } + } + + /* Look for the datagram the fragment belongs to in the current datagram queue, + * remembering the previous in the queue for later dequeueing. */ + for (ipr = reassdatagrams; ipr != NULL; ipr = ipr->next) { + /* Check if the incoming fragment matches the one currently present + in the reassembly buffer. If so, we proceed with copying the + fragment into the buffer. */ + if (IP_ADDRESSES_AND_ID_MATCH(&ipr->iphdr, fraghdr)) { + LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: matching previous fragment ID=%"X16_F"\n", + lwip_ntohs(IPH_ID(fraghdr)))); + IPFRAG_STATS_INC(ip_frag.cachehit); + break; + } + } + + if (ipr == NULL) { + /* Enqueue a new datagram into the datagram queue */ + ipr = ip_reass_enqueue_new_datagram(fraghdr, clen); + /* Bail if unable to enqueue */ + if (ipr == NULL) { + goto nullreturn; + } + } else { + if (((lwip_ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) == 0) && + ((lwip_ntohs(IPH_OFFSET(&ipr->iphdr)) & IP_OFFMASK) != 0)) { + /* ipr->iphdr is not the header from the first fragment, but fraghdr is + * -> copy fraghdr into ipr->iphdr since we want to have the header + * of the first fragment (for ICMP time exceeded and later, for copying + * all options, if supported)*/ + SMEMCPY(&ipr->iphdr, fraghdr, IP_HLEN); + } + } + + /* At this point, we have either created a new entry or pointing + * to an existing one */ + + /* check for 'no more fragments', and update queue entry*/ + is_last = (IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0; + if (is_last) { + u16_t datagram_len = (u16_t)(offset + len); + if ((datagram_len < offset) || (datagram_len > (0xFFFF - IP_HLEN))) { + /* u16_t overflow, cannot handle this */ + goto nullreturn_ipr; + } + } + /* find the right place to insert this pbuf */ + /* @todo: trim pbufs if fragments are overlapping */ + valid = ip_reass_chain_frag_into_datagram_and_validate(ipr, p, is_last); + if (valid == IP_REASS_VALIDATE_PBUF_DROPPED) { + goto nullreturn_ipr; + } + /* if we come here, the pbuf has been enqueued */ + + /* Track the current number of pbufs current 'in-flight', in order to limit + the number of fragments that may be enqueued at any one time + (overflow checked by testing against IP_REASS_MAX_PBUFS) */ + ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount + clen); + if (is_last) { + u16_t datagram_len = (u16_t)(offset + len); + ipr->datagram_len = datagram_len; + ipr->flags |= IP_REASS_FLAG_LASTFRAG; + LWIP_DEBUGF(IP_REASS_DEBUG, + ("ip4_reass: last fragment seen, total len %"S16_F"\n", + ipr->datagram_len)); + } + + if (valid == IP_REASS_VALIDATE_TELEGRAM_FINISHED) { + struct ip_reassdata *ipr_prev; + /* the totally last fragment (flag more fragments = 0) was received at least + * once AND all fragments are received */ + u16_t datagram_len = (u16_t)(ipr->datagram_len + IP_HLEN); + + /* save the second pbuf before copying the header over the pointer */ + r = ((struct ip_reass_helper *)ipr->p->payload)->next_pbuf; + + /* copy the original ip header back to the first pbuf */ + fraghdr = (struct ip_hdr *)(ipr->p->payload); + SMEMCPY(fraghdr, &ipr->iphdr, IP_HLEN); + IPH_LEN_SET(fraghdr, lwip_htons(datagram_len)); + IPH_OFFSET_SET(fraghdr, 0); + IPH_CHKSUM_SET(fraghdr, 0); + /* @todo: do we need to set/calculate the correct checksum? */ +#if CHECKSUM_GEN_IP + IF__NETIF_CHECKSUM_ENABLED(ip_current_input_netif(), NETIF_CHECKSUM_GEN_IP) { + IPH_CHKSUM_SET(fraghdr, inet_chksum(fraghdr, IP_HLEN)); + } +#endif /* CHECKSUM_GEN_IP */ + + p = ipr->p; + + /* chain together the pbufs contained within the reass_data list. */ + while (r != NULL) { + iprh = (struct ip_reass_helper *)r->payload; + + /* hide the ip header for every succeeding fragment */ + pbuf_remove_header(r, IP_HLEN); + pbuf_cat(p, r); + r = iprh->next_pbuf; + } + + /* find the previous entry in the linked list */ + if (ipr == reassdatagrams) { + ipr_prev = NULL; + } else { + for (ipr_prev = reassdatagrams; ipr_prev != NULL; ipr_prev = ipr_prev->next) { + if (ipr_prev->next == ipr) { + break; + } + } + } + + /* release the sources allocate for the fragment queue entry */ + ip_reass_dequeue_datagram(ipr, ipr_prev); + + /* and adjust the number of pbufs currently queued for reassembly. */ + clen = pbuf_clen(p); + LWIP_ASSERT("ip_reass_pbufcount >= clen", ip_reass_pbufcount >= clen); + ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount - clen); + + MIB2_STATS_INC(mib2.ipreasmoks); + + /* Return the pbuf chain */ + return p; + } + /* the datagram is not (yet?) reassembled completely */ + LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_pbufcount: %d out\n", ip_reass_pbufcount)); + return NULL; + +nullreturn_ipr: + LWIP_ASSERT("ipr != NULL", ipr != NULL); + if (ipr->p == NULL) { + /* dropped pbuf after creating a new datagram entry: remove the entry, too */ + LWIP_ASSERT("not firstalthough just enqueued", ipr == reassdatagrams); + ip_reass_dequeue_datagram(ipr, NULL); + } + +nullreturn: + LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: nullreturn\n")); + IPFRAG_STATS_INC(ip_frag.drop); + pbuf_free(p); + return NULL; +} +#endif /* IP_REASSEMBLY */ + +#if IP_FRAG +#if !LWIP_NETIF_TX_SINGLE_PBUF +/** Allocate a new struct pbuf_custom_ref */ +static struct pbuf_custom_ref * +ip_frag_alloc_pbuf_custom_ref(void) +{ + return (struct pbuf_custom_ref *)memp_malloc(MEMP_FRAG_PBUF); +} + +/** Free a struct pbuf_custom_ref */ +static void +ip_frag_free_pbuf_custom_ref(struct pbuf_custom_ref *p) +{ + LWIP_ASSERT("p != NULL", p != NULL); + memp_free(MEMP_FRAG_PBUF, p); +} + +/** Free-callback function to free a 'struct pbuf_custom_ref', called by + * pbuf_free. */ +static void +ipfrag_free_pbuf_custom(struct pbuf *p) +{ + struct pbuf_custom_ref *pcr = (struct pbuf_custom_ref *)p; + LWIP_ASSERT("pcr != NULL", pcr != NULL); + LWIP_ASSERT("pcr == p", (void *)pcr == (void *)p); + if (pcr->original != NULL) { + pbuf_free(pcr->original); + } + ip_frag_free_pbuf_custom_ref(pcr); +} +#endif /* !LWIP_NETIF_TX_SINGLE_PBUF */ + +/** + * Fragment an IP datagram if too large for the netif. + * + * Chop the datagram in MTU sized chunks and send them in order + * by pointing PBUF_REFs into p. + * + * @param p ip packet to send + * @param netif the netif on which to send + * @param dest destination ip address to which to send + * + * @return ERR_OK if sent successfully, err_t otherwise + */ +err_t +ip4_frag(struct pbuf *p, struct netif *netif, const ip4_addr_t *dest) +{ + struct pbuf *rambuf; +#if !LWIP_NETIF_TX_SINGLE_PBUF + struct pbuf *newpbuf; + u16_t newpbuflen = 0; + u16_t left_to_copy; +#endif + struct ip_hdr *original_iphdr; + struct ip_hdr *iphdr; + const u16_t nfb = (u16_t)((netif->mtu - IP_HLEN) / 8); + u16_t left, fragsize; + u16_t ofo; + int last; + u16_t poff = IP_HLEN; + u16_t tmp; + int mf_set; + + original_iphdr = (struct ip_hdr *)p->payload; + iphdr = original_iphdr; + if (IPH_HL_BYTES(iphdr) != IP_HLEN) { + /* ip4_frag() does not support IP options */ + return ERR_VAL; + } + LWIP_ERROR("ip4_frag(): pbuf too short", p->len >= IP_HLEN, return ERR_VAL); + + /* Save original offset */ + tmp = lwip_ntohs(IPH_OFFSET(iphdr)); + ofo = tmp & IP_OFFMASK; + /* already fragmented? if so, the last fragment we create must have MF, too */ + mf_set = tmp & IP_MF; + + left = (u16_t)(p->tot_len - IP_HLEN); + + while (left) { + /* Fill this fragment */ + fragsize = LWIP_MIN(left, (u16_t)(nfb * 8)); + +#if LWIP_NETIF_TX_SINGLE_PBUF + rambuf = pbuf_alloc(PBUF_IP, fragsize, PBUF_RAM); + if (rambuf == NULL) { + goto memerr; + } + LWIP_ASSERT("this needs a pbuf in one piece!", + (rambuf->len == rambuf->tot_len) && (rambuf->next == NULL)); + poff += pbuf_copy_partial(p, rambuf->payload, fragsize, poff); + /* make room for the IP header */ + if (pbuf_add_header(rambuf, IP_HLEN)) { + pbuf_free(rambuf); + goto memerr; + } + /* fill in the IP header */ + SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN); + iphdr = (struct ip_hdr *)rambuf->payload; +#else /* LWIP_NETIF_TX_SINGLE_PBUF */ + /* When not using a static buffer, create a chain of pbufs. + * The first will be a PBUF_RAM holding the link and IP header. + * The rest will be PBUF_REFs mirroring the pbuf chain to be fragged, + * but limited to the size of an mtu. + */ + rambuf = pbuf_alloc(PBUF_LINK, IP_HLEN, PBUF_RAM); + if (rambuf == NULL) { + goto memerr; + } + LWIP_ASSERT("this needs a pbuf in one piece!", + (rambuf->len >= (IP_HLEN))); + SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN); + iphdr = (struct ip_hdr *)rambuf->payload; + + left_to_copy = fragsize; + while (left_to_copy) { + struct pbuf_custom_ref *pcr; + u16_t plen = (u16_t)(p->len - poff); + LWIP_ASSERT("p->len >= poff", p->len >= poff); + newpbuflen = LWIP_MIN(left_to_copy, plen); + /* Is this pbuf already empty? */ + if (!newpbuflen) { + poff = 0; + p = p->next; + continue; + } + pcr = ip_frag_alloc_pbuf_custom_ref(); + if (pcr == NULL) { + pbuf_free(rambuf); + goto memerr; + } + /* Mirror this pbuf, although we might not need all of it. */ + newpbuf = pbuf_alloced_custom(PBUF_RAW, newpbuflen, PBUF_REF, &pcr->pc, + (u8_t *)p->payload + poff, newpbuflen); + if (newpbuf == NULL) { + ip_frag_free_pbuf_custom_ref(pcr); + pbuf_free(rambuf); + goto memerr; + } + pbuf_ref(p); + pcr->original = p; + pcr->pc.custom_free_function = ipfrag_free_pbuf_custom; + + /* Add it to end of rambuf's chain, but using pbuf_cat, not pbuf_chain + * so that it is removed when pbuf_dechain is later called on rambuf. + */ + pbuf_cat(rambuf, newpbuf); + left_to_copy = (u16_t)(left_to_copy - newpbuflen); + if (left_to_copy) { + poff = 0; + p = p->next; + } + } + poff = (u16_t)(poff + newpbuflen); +#endif /* LWIP_NETIF_TX_SINGLE_PBUF */ + + /* Correct header */ + last = (left <= netif->mtu - IP_HLEN); + + /* Set new offset and MF flag */ + tmp = (IP_OFFMASK & (ofo)); + if (!last || mf_set) { + /* the last fragment has MF set if the input frame had it */ + tmp = tmp | IP_MF; + } + IPH_OFFSET_SET(iphdr, lwip_htons(tmp)); + IPH_LEN_SET(iphdr, lwip_htons((u16_t)(fragsize + IP_HLEN))); + IPH_CHKSUM_SET(iphdr, 0); +#if CHECKSUM_GEN_IP + IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) { + IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN)); + } +#endif /* CHECKSUM_GEN_IP */ + + /* No need for separate header pbuf - we allowed room for it in rambuf + * when allocated. + */ + netif->output(netif, rambuf, dest); + IPFRAG_STATS_INC(ip_frag.xmit); + + /* Unfortunately we can't reuse rambuf - the hardware may still be + * using the buffer. Instead we free it (and the ensuing chain) and + * recreate it next time round the loop. If we're lucky the hardware + * will have already sent the packet, the free will really free, and + * there will be zero memory penalty. + */ + + pbuf_free(rambuf); + left = (u16_t)(left - fragsize); + ofo = (u16_t)(ofo + nfb); + } + MIB2_STATS_INC(mib2.ipfragoks); + return ERR_OK; +memerr: + MIB2_STATS_INC(mib2.ipfragfails); + return ERR_MEM; +} +#endif /* IP_FRAG */ + +#endif /* LWIP_IPV4 */ |