| /** |
| * @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 */ |