BadVPN – Rev 1
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/**
* @file
*
* IPv6 fragmentation and reassembly.
*/
/*
* Copyright (c) 2010 Inico Technologies Ltd.
* 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: Ivan Delamer <delamer@inicotech.com>
*
*
* Please coordinate changes and requests with Ivan Delamer
* <delamer@inicotech.com>
*/
#include "lwip/opt.h"
#include "lwip/ip6_frag.h"
#include "lwip/ip6.h"
#include "lwip/icmp6.h"
#include "lwip/nd6.h"
#include "lwip/ip.h"
#include "lwip/pbuf.h"
#include "lwip/memp.h"
#include "lwip/stats.h"
#include <string.h>
#if LWIP_IPV6 && LWIP_IPV6_REASS /* don't build if not configured for use in lwipopts.h */
/** 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 */
#if IPV6_FRAG_COPYHEADER
/* The number of bytes we need to "borrow" from (i.e., overwrite in) the header
* that precedes the fragment header for reassembly pruposes. */
#define IPV6_FRAG_REQROOM ((s16_t)(sizeof(struct ip6_reass_helper) - IP6_FRAG_HLEN))
#endif
#define IP_REASS_FLAG_LASTFRAG 0x01
/** 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 IPv6 header, since it replaces
* the Fragment Header in memory in incoming fragments to keep
* track of the various fragments.
*/
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
struct ip6_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
/* static variables */
static struct ip6_reassdata *reassdatagrams;
static u16_t ip6_reass_pbufcount;
/* Forward declarations. */
static void ip6_reass_free_complete_datagram(struct ip6_reassdata *ipr);
#if IP_REASS_FREE_OLDEST
static void ip6_reass_remove_oldest_datagram(struct ip6_reassdata *ipr, int pbufs_needed);
#endif /* IP_REASS_FREE_OLDEST */
void
ip6_reass_tmr(void)
{
struct ip6_reassdata *r, *tmp;
#if !IPV6_FRAG_COPYHEADER
LWIP_ASSERT("sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN, set IPV6_FRAG_COPYHEADER to 1",
sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN);
#endif /* !IPV6_FRAG_COPYHEADER */
r = reassdatagrams;
while (r != NULL) {
/* Decrement the timer. Once it reaches 0,
* clean up the incomplete fragment assembly */
if (r->timer > 0) {
r->timer--;
r = r->next;
} else {
/* reassembly timed out */
tmp = r;
/* get the next pointer before freeing */
r = r->next;
/* free the helper struct and all enqueued pbufs */
ip6_reass_free_complete_datagram(tmp);
}
}
}
/**
* Free a datagram (struct ip6_reassdata) and all its pbufs.
* Updates the total count of enqueued pbufs (ip6_reass_pbufcount),
* sends an ICMP time exceeded packet.
*
* @param ipr datagram to free
*/
static void
ip6_reass_free_complete_datagram(struct ip6_reassdata *ipr)
{
struct ip6_reassdata *prev;
u16_t pbufs_freed = 0;
u16_t clen;
struct pbuf *p;
struct ip6_reass_helper *iprh;
#if LWIP_ICMP6
iprh = (struct ip6_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;
/* Restore the part that we've overwritten with our helper structure, or we
* might send garbage (and disclose a pointer) in the ICMPv6 reply. */
MEMCPY(p->payload, ipr->orig_hdr, sizeof(iprh));
/* Then, move back to the original ipv6 header (we are now pointing to Fragment header).
This cannot fail since we already checked when receiving this fragment. */
if (pbuf_header_force(p, (s16_t)((u8_t*)p->payload - (u8_t*)ipr->iphdr))) {
LWIP_ASSERT("ip6_reass_free: moving p->payload to ip6 header failed\n", 0);
}
else {
/* Reconstruct the zoned source and destination addresses, so that we do
* not end up sending the ICMP response over the wrong link. */
ip6_addr_t src_addr, dest_addr;
ip6_addr_copy_from_packed(src_addr, IPV6_FRAG_SRC(ipr));
ip6_addr_set_zone(&src_addr, ipr->src_zone);
ip6_addr_copy_from_packed(dest_addr, IPV6_FRAG_DEST(ipr));
ip6_addr_set_zone(&dest_addr, ipr->dest_zone);
/* Send the actual ICMP response. */
icmp6_time_exceeded_with_addrs(p, ICMP6_TE_FRAG, &src_addr, &dest_addr);
}
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_ICMP6 */
/* 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 ip6_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 ip6_reassdata from the list and free it. */
if (ipr == reassdatagrams) {
reassdatagrams = ipr->next;
} else {
prev = reassdatagrams;
while (prev != NULL) {
if (prev->next == ipr) {
break;
}
prev = prev->next;
}
if (prev != NULL) {
prev->next = ipr->next;
}
}
memp_free(MEMP_IP6_REASSDATA, ipr);
/* Finally, update number of pbufs in reassembly queue */
LWIP_ASSERT("ip_reass_pbufcount >= clen", ip6_reass_pbufcount >= pbufs_freed);
ip6_reass_pbufcount = (u16_t)(ip6_reass_pbufcount - pbufs_freed);
}
#if IP_REASS_FREE_OLDEST
/**
* Free the oldest datagram to make room for enqueueing new fragments.
* The datagram ipr is not freed!
*
* @param ipr ip6_reassdata for the current fragment
* @param pbufs_needed number of pbufs needed to enqueue
* (used for freeing other datagrams if not enough space)
*/
static void
ip6_reass_remove_oldest_datagram(struct ip6_reassdata *ipr, int pbufs_needed)
{
struct ip6_reassdata *r, *oldest;
/* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs,
* but don't free the current datagram! */
do {
r = oldest = reassdatagrams;
while (r != NULL) {
if (r != ipr) {
if (r->timer <= oldest->timer) {
/* older than the previous oldest */
oldest = r;
}
}
r = r->next;
}
if (oldest == ipr) {
/* nothing to free, ipr is the only element on the list */
return;
}
if (oldest != NULL) {
ip6_reass_free_complete_datagram(oldest);
}
} while (((ip6_reass_pbufcount + pbufs_needed) > IP_REASS_MAX_PBUFS) && (reassdatagrams != NULL));
}
#endif /* IP_REASS_FREE_OLDEST */
/**
* Reassembles incoming IPv6 fragments into an IPv6 datagram.
*
* @param p points to the IPv6 Fragment Header
* @return NULL if reassembly is incomplete, pbuf pointing to
* IPv6 Header if reassembly is complete
*/
struct pbuf *
ip6_reass(struct pbuf *p)
{
struct ip6_reassdata *ipr, *ipr_prev;
struct ip6_reass_helper *iprh, *iprh_tmp, *iprh_prev=NULL;
struct ip6_frag_hdr *frag_hdr;
u16_t offset, len, start, end;
ptrdiff_t hdrdiff;
u16_t clen;
u8_t valid = 1;
struct pbuf *q, *next_pbuf;
IP6_FRAG_STATS_INC(ip6_frag.recv);
/* ip6_frag_hdr must be in the first pbuf, not chained. Checked by caller. */
LWIP_ASSERT("IPv6 fragment header does not fit in first pbuf",
p->len >= sizeof(struct ip6_frag_hdr));
frag_hdr = (struct ip6_frag_hdr *) p->payload;
clen = pbuf_clen(p);
offset = lwip_ntohs(frag_hdr->_fragment_offset);
/* Calculate fragment length from IPv6 payload length.
* Adjust for headers before Fragment Header.
* And finally adjust by Fragment Header length. */
len = lwip_ntohs(ip6_current_header()->_plen);
hdrdiff = (u8_t*)p->payload - (const u8_t*)ip6_current_header();
LWIP_ASSERT("not a valid pbuf (ip6_input check missing?)", hdrdiff <= 0xFFFF);
LWIP_ASSERT("not a valid pbuf (ip6_input check missing?)", hdrdiff >= IP6_HLEN);
hdrdiff -= IP6_HLEN;
hdrdiff += IP6_FRAG_HLEN;
if (hdrdiff > len) {
IP6_FRAG_STATS_INC(ip6_frag.proterr);
goto nullreturn;
}
len = (u16_t)(len - hdrdiff);
start = (offset & IP6_FRAG_OFFSET_MASK);
if (start > (0xFFFF - len)) {
/* u16_t overflow, cannot handle this */
IP6_FRAG_STATS_INC(ip6_frag.proterr);
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_prev = NULL; 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 ((frag_hdr->_identification == ipr->identification) &&
ip6_addr_cmp_packed(ip6_current_src_addr(), &(IPV6_FRAG_SRC(ipr)), ipr->src_zone) &&
ip6_addr_cmp_packed(ip6_current_dest_addr(), &(IPV6_FRAG_DEST(ipr)), ipr->dest_zone)) {
IP6_FRAG_STATS_INC(ip6_frag.cachehit);
break;
}
ipr_prev = ipr;
}
if (ipr == NULL) {
/* Enqueue a new datagram into the datagram queue */
ipr = (struct ip6_reassdata *)memp_malloc(MEMP_IP6_REASSDATA);
if (ipr == NULL) {
#if IP_REASS_FREE_OLDEST
/* Make room and try again. */
ip6_reass_remove_oldest_datagram(ipr, clen);
ipr = (struct ip6_reassdata *)memp_malloc(MEMP_IP6_REASSDATA);
if (ipr != NULL) {
/* re-search ipr_prev since it might have been removed */
for (ipr_prev = reassdatagrams; ipr_prev != NULL; ipr_prev = ipr_prev->next) {
if (ipr_prev->next == ipr) {
break;
}
}
} else
#endif /* IP_REASS_FREE_OLDEST */
{
IP6_FRAG_STATS_INC(ip6_frag.memerr);
goto nullreturn;
}
}
memset(ipr, 0, sizeof(struct ip6_reassdata));
ipr->timer = IPV6_REASS_MAXAGE;
/* enqueue the new structure to the front of the list */
ipr->next = reassdatagrams;
reassdatagrams = ipr;
/* Use the current IPv6 header for src/dest address reference.
* Eventually, we will replace it when we get the first fragment
* (it might be this one, in any case, it is done later). */
/* need to use the none-const pointer here: */
ipr->iphdr = ip_data.current_ip6_header;
#if IPV6_FRAG_COPYHEADER
MEMCPY(&ipr->src, &ip6_current_header()->src, sizeof(ipr->src));
MEMCPY(&ipr->dest, &ip6_current_header()->dest, sizeof(ipr->dest));
#endif /* IPV6_FRAG_COPYHEADER */
#if LWIP_IPV6_SCOPES
/* Also store the address zone information.
* @todo It is possible that due to netif destruction and recreation, the
* stored zones end up resolving to a different interface. In that case, we
* risk sending a "time exceeded" ICMP response over the wrong link.
* Ideally, netif destruction would clean up matching pending reassembly
* structures, but custom zone mappings would make that non-trivial. */
ipr->src_zone = ip6_addr_zone(ip6_current_src_addr());
ipr->dest_zone = ip6_addr_zone(ip6_current_dest_addr());
#endif /* LWIP_IPV6_SCOPES */
/* copy the fragmented packet id. */
ipr->identification = frag_hdr->_identification;
/* copy the nexth field */
ipr->nexth = frag_hdr->_nexth;
}
/* Check if we are allowed to enqueue more datagrams. */
if ((ip6_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS) {
#if IP_REASS_FREE_OLDEST
ip6_reass_remove_oldest_datagram(ipr, clen);
if ((ip6_reass_pbufcount + clen) <= IP_REASS_MAX_PBUFS) {
/* re-search ipr_prev since it might have been removed */
for (ipr_prev = reassdatagrams; ipr_prev != NULL; ipr_prev = ipr_prev->next) {
if (ipr_prev->next == ipr) {
break;
}
}
} else
#endif /* IP_REASS_FREE_OLDEST */
{
/* @todo: send ICMPv6 time exceeded here? */
/* drop this pbuf */
IP6_FRAG_STATS_INC(ip6_frag.memerr);
goto nullreturn;
}
}
/* Overwrite Fragment Header with our own helper struct. */
#if IPV6_FRAG_COPYHEADER
if (IPV6_FRAG_REQROOM > 0) {
/* Make room for struct ip6_reass_helper (only required if sizeof(void*) > 4).
This cannot fail since we already checked when receiving this fragment. */
u8_t hdrerr = pbuf_header_force(p, IPV6_FRAG_REQROOM);
LWIP_UNUSED_ARG(hdrerr); /* in case of LWIP_NOASSERT */
LWIP_ASSERT("no room for struct ip6_reass_helper", hdrerr == 0);
}
#else /* IPV6_FRAG_COPYHEADER */
LWIP_ASSERT("sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN, set IPV6_FRAG_COPYHEADER to 1",
sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN);
#endif /* IPV6_FRAG_COPYHEADER */
/* Prepare the pointer to the helper structure, and its initial values.
* Do not yet write to the structure itself, as we still have to make a
* backup of the original data, and we should not do that until we know for
* sure that we are going to add this packet to the list. */
iprh = (struct ip6_reass_helper *)p->payload;
next_pbuf = NULL;
end = (u16_t)(start + len);
/* find the right place to insert this pbuf */
/* Iterate through until we either get to the end of the list (append),
* or we find on with a larger offset (insert). */
for (q = ipr->p; q != NULL;) {
iprh_tmp = (struct ip6_reass_helper*)q->payload;
if (start < iprh_tmp->start) {
#if IP_REASS_CHECK_OVERLAP
if (end > iprh_tmp->start) {
/* fragment overlaps with following, throw away */
IP6_FRAG_STATS_INC(ip6_frag.proterr);
goto nullreturn;
}
if (iprh_prev != NULL) {
if (start < iprh_prev->end) {
/* fragment overlaps with previous, throw away */
IP6_FRAG_STATS_INC(ip6_frag.proterr);
goto nullreturn;
}
}
#endif /* IP_REASS_CHECK_OVERLAP */
/* the new pbuf should be inserted before this */
next_pbuf = q;
if (iprh_prev != NULL) {
/* not the fragment with the lowest offset */
iprh_prev->next_pbuf = p;
} else {
/* fragment with the lowest offset */
ipr->p = p;
}
break;
} else if (start == iprh_tmp->start) {
/* received the same datagram twice: no need to keep the datagram */
goto nullreturn;
#if IP_REASS_CHECK_OVERLAP
} else if (start < iprh_tmp->end) {
/* overlap: no need to keep the new datagram */
IP6_FRAG_STATS_INC(ip6_frag.proterr);
goto nullreturn;
#endif /* IP_REASS_CHECK_OVERLAP */
} else {
/* Check if the fragments received so far have no gaps. */
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 <= start);
#endif /* IP_REASS_CHECK_OVERLAP */
iprh_prev->next_pbuf = p;
if (iprh_prev->end != 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 = p;
}
}
/* 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 */
ip6_reass_pbufcount = (u16_t)(ip6_reass_pbufcount + clen);
/* Remember IPv6 header if this is the first fragment. */
if (start == 0) {
/* need to use the none-const pointer here: */
ipr->iphdr = ip_data.current_ip6_header;
/* Make a backup of the part of the packet data that we are about to
* overwrite, so that we can restore the original later. */
MEMCPY(ipr->orig_hdr, p->payload, sizeof(*iprh));
/* For IPV6_FRAG_COPYHEADER there is no need to copy src/dst again, as they
* will be the same as they were. With LWIP_IPV6_SCOPES, the same applies
* to the source/destination zones. */
}
/* Only after the backup do we get to fill in the actual helper structure. */
iprh->next_pbuf = next_pbuf;
iprh->start = start;
iprh->end = end;
/* If this is the last fragment, calculate total packet length. */
if ((offset & IP6_FRAG_MORE_FLAG) == 0) {
ipr->datagram_len = iprh->end;
}
/* Additional validity tests: we have received first and last fragment. */
iprh_tmp = (struct ip6_reass_helper*)ipr->p->payload;
if (iprh_tmp->start != 0) {
valid = 0;
}
if (ipr->datagram_len == 0) {
valid = 0;
}
/* Final validity test: no gaps between current and last fragment. */
iprh_prev = iprh;
q = iprh->next_pbuf;
while ((q != NULL) && valid) {
iprh = (struct ip6_reass_helper*)q->payload;
if (iprh_prev->end != iprh->start) {
valid = 0;
break;
}
iprh_prev = iprh;
q = iprh->next_pbuf;
}
if (valid) {
/* All fragments have been received */
struct ip6_hdr* iphdr_ptr;
/* chain together the pbufs contained within the ip6_reassdata list. */
iprh = (struct ip6_reass_helper*) ipr->p->payload;
while (iprh != NULL) {
next_pbuf = iprh->next_pbuf;
if (next_pbuf != NULL) {
/* Save next helper struct (will be hidden in next step). */
iprh_tmp = (struct ip6_reass_helper*)next_pbuf->payload;
/* hide the fragment header for every succeeding fragment */
pbuf_remove_header(next_pbuf, IP6_FRAG_HLEN);
#if IPV6_FRAG_COPYHEADER
if (IPV6_FRAG_REQROOM > 0) {
/* hide the extra bytes borrowed from ip6_hdr for struct ip6_reass_helper */
u8_t hdrerr = pbuf_remove_header(next_pbuf, IPV6_FRAG_REQROOM);
LWIP_UNUSED_ARG(hdrerr); /* in case of LWIP_NOASSERT */
LWIP_ASSERT("no room for struct ip6_reass_helper", hdrerr == 0);
}
#endif
pbuf_cat(ipr->p, next_pbuf);
}
else {
iprh_tmp = NULL;
}
iprh = iprh_tmp;
}
/* Get the first pbuf. */
p = ipr->p;
#if IPV6_FRAG_COPYHEADER
if (IPV6_FRAG_REQROOM > 0) {
u8_t hdrerr;
/* Restore (only) the bytes that we overwrote beyond the fragment header.
* Those bytes may belong to either the IPv6 header or an extension
* header placed before the fragment header. */
MEMCPY(p->payload, ipr->orig_hdr, IPV6_FRAG_REQROOM);
/* get back room for struct ip6_reass_helper (only required if sizeof(void*) > 4) */
hdrerr = pbuf_remove_header(p, IPV6_FRAG_REQROOM);
LWIP_UNUSED_ARG(hdrerr); /* in case of LWIP_NOASSERT */
LWIP_ASSERT("no room for struct ip6_reass_helper", hdrerr == 0);
}
#endif
/* We need to get rid of the fragment header itself, which is somewhere in
* the middle of the packet (but still in the first pbuf of the chain).
* Getting rid of the header is required by RFC 2460 Sec. 4.5 and necessary
* in order to be able to reassemble packets that are close to full size
* (i.e., around 65535 bytes). We simply move up all the headers before the
* fragment header, including the IPv6 header, and adjust the payload start
* accordingly. This works because all these headers are in the first pbuf
* of the chain, and because the caller adjusts all its pointers on
* successful reassembly. */
MEMMOVE((u8_t*)ipr->iphdr + sizeof(struct ip6_frag_hdr), ipr->iphdr,
(size_t)((u8_t*)p->payload - (u8_t*)ipr->iphdr));
/* This is where the IPv6 header is now. */
iphdr_ptr = (struct ip6_hdr*)((u8_t*)ipr->iphdr +
sizeof(struct ip6_frag_hdr));
/* Adjust datagram length by adding header lengths. */
ipr->datagram_len = (u16_t)(ipr->datagram_len + ((u8_t*)p->payload - (u8_t*)iphdr_ptr)
- IP6_HLEN);
/* Set payload length in ip header. */
iphdr_ptr->_plen = lwip_htons(ipr->datagram_len);
/* With the fragment header gone, we now need to adjust the next-header
* field of whatever header was originally before it. Since the packet made
* it through the original header processing routines at least up to the
* fragment header, we do not need any further sanity checks here. */
if (IP6H_NEXTH(iphdr_ptr) == IP6_NEXTH_FRAGMENT) {
iphdr_ptr->_nexth = ipr->nexth;
} else {
u8_t *ptr = (u8_t *)iphdr_ptr + IP6_HLEN;
while (*ptr != IP6_NEXTH_FRAGMENT) {
ptr += 8 * (1 + ptr[1]);
}
*ptr = ipr->nexth;
}
/* release the resources allocated for the fragment queue entry */
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", ipr_prev != NULL);
ipr_prev->next = ipr->next;
}
memp_free(MEMP_IP6_REASSDATA, ipr);
/* adjust the number of pbufs currently queued for reassembly. */
clen = pbuf_clen(p);
LWIP_ASSERT("ip6_reass_pbufcount >= clen", ip6_reass_pbufcount >= clen);
ip6_reass_pbufcount = (u16_t)(ip6_reass_pbufcount - clen);
/* Move pbuf back to IPv6 header. This should never fail. */
if (pbuf_header_force(p, (s16_t)((u8_t*)p->payload - (u8_t*)iphdr_ptr))) {
LWIP_ASSERT("ip6_reass: moving p->payload to ip6 header failed\n", 0);
pbuf_free(p);
return NULL;
}
/* Return the pbuf chain */
return p;
}
/* the datagram is not (yet?) reassembled completely */
return NULL;
nullreturn:
IP6_FRAG_STATS_INC(ip6_frag.drop);
pbuf_free(p);
return NULL;
}
#endif /* LWIP_IPV6 && LWIP_IPV6_REASS */
#if LWIP_IPV6 && LWIP_IPV6_FRAG
#if !LWIP_NETIF_TX_SINGLE_PBUF
/** Allocate a new struct pbuf_custom_ref */
static struct pbuf_custom_ref*
ip6_frag_alloc_pbuf_custom_ref(void)
{
return (struct pbuf_custom_ref*)memp_malloc(MEMP_FRAG_PBUF);
}
/** Free a struct pbuf_custom_ref */
static void
ip6_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
ip6_frag_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);
}
ip6_frag_free_pbuf_custom_ref(pcr);
}
#endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
/**
* Fragment an IPv6 datagram if too large for the netif or path MTU.
*
* Chop the datagram in MTU sized chunks and send them in order
* by pointing PBUF_REFs into p
*
* @param p ipv6 packet to send
* @param netif the netif on which to send
* @param dest destination ipv6 address to which to send
*
* @return ERR_OK if sent successfully, err_t otherwise
*/
err_t
ip6_frag(struct pbuf *p, struct netif *netif, const ip6_addr_t *dest)
{
struct ip6_hdr *original_ip6hdr;
struct ip6_hdr *ip6hdr;
struct ip6_frag_hdr *frag_hdr;
struct pbuf *rambuf;
#if !LWIP_NETIF_TX_SINGLE_PBUF
struct pbuf *newpbuf;
u16_t newpbuflen = 0;
u16_t left_to_copy;
#endif
static u32_t identification;
u16_t left, cop;
const u16_t mtu = nd6_get_destination_mtu(dest, netif);
const u16_t nfb = (u16_t)((mtu - (IP6_HLEN + IP6_FRAG_HLEN)) & IP6_FRAG_OFFSET_MASK);
u16_t fragment_offset = 0;
u16_t last;
u16_t poff = IP6_HLEN;
identification++;
original_ip6hdr = (struct ip6_hdr *)p->payload;
/* @todo we assume there are no options in the unfragmentable part (IPv6 header). */
LWIP_ASSERT("p->tot_len >= IP6_HLEN", p->tot_len >= IP6_HLEN);
left = (u16_t)(p->tot_len - IP6_HLEN);
while (left) {
last = (left <= nfb);
/* Fill this fragment */
cop = last ? left : nfb;
#if LWIP_NETIF_TX_SINGLE_PBUF
rambuf = pbuf_alloc(PBUF_IP, cop + IP6_FRAG_HLEN, PBUF_RAM);
if (rambuf == NULL) {
IP6_FRAG_STATS_INC(ip6_frag.memerr);
return ERR_MEM;
}
LWIP_ASSERT("this needs a pbuf in one piece!",
(rambuf->len == rambuf->tot_len) && (rambuf->next == NULL));
poff += pbuf_copy_partial(p, (u8_t*)rambuf->payload + IP6_FRAG_HLEN, cop, poff);
/* make room for the IP header */
if (pbuf_add_header(rambuf, IP6_HLEN)) {
pbuf_free(rambuf);
IP6_FRAG_STATS_INC(ip6_frag.memerr);
return ERR_MEM;
}
/* fill in the IP header */
SMEMCPY(rambuf->payload, original_ip6hdr, IP6_HLEN);
ip6hdr = (struct ip6_hdr *)rambuf->payload;
frag_hdr = (struct ip6_frag_hdr *)((u8_t*)rambuf->payload + IP6_HLEN);
#else
/* When not using a static buffer, create a chain of pbufs.
* The first will be a PBUF_RAM holding the link, IPv6, and Fragment 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, IP6_HLEN + IP6_FRAG_HLEN, PBUF_RAM);
if (rambuf == NULL) {
IP6_FRAG_STATS_INC(ip6_frag.memerr);
return ERR_MEM;
}
LWIP_ASSERT("this needs a pbuf in one piece!",
(p->len >= (IP6_HLEN)));
SMEMCPY(rambuf->payload, original_ip6hdr, IP6_HLEN);
ip6hdr = (struct ip6_hdr *)rambuf->payload;
frag_hdr = (struct ip6_frag_hdr *)((u8_t*)rambuf->payload + IP6_HLEN);
/* Can just adjust p directly for needed offset. */
p->payload = (u8_t *)p->payload + poff;
p->len = (u16_t)(p->len - poff);
p->tot_len = (u16_t)(p->tot_len - poff);
left_to_copy = cop;
while (left_to_copy) {
struct pbuf_custom_ref *pcr;
newpbuflen = (left_to_copy < p->len) ? left_to_copy : p->len;
/* Is this pbuf already empty? */
if (!newpbuflen) {
p = p->next;
continue;
}
pcr = ip6_frag_alloc_pbuf_custom_ref();
if (pcr == NULL) {
pbuf_free(rambuf);
IP6_FRAG_STATS_INC(ip6_frag.memerr);
return ERR_MEM;
}
/* Mirror this pbuf, although we might not need all of it. */
newpbuf = pbuf_alloced_custom(PBUF_RAW, newpbuflen, PBUF_REF, &pcr->pc, p->payload, newpbuflen);
if (newpbuf == NULL) {
ip6_frag_free_pbuf_custom_ref(pcr);
pbuf_free(rambuf);
IP6_FRAG_STATS_INC(ip6_frag.memerr);
return ERR_MEM;
}
pbuf_ref(p);
pcr->original = p;
pcr->pc.custom_free_function = ip6_frag_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) {
p = p->next;
}
}
poff = newpbuflen;
#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
/* Set headers */
frag_hdr->_nexth = original_ip6hdr->_nexth;
frag_hdr->reserved = 0;
frag_hdr->_fragment_offset = lwip_htons((u16_t)((fragment_offset & IP6_FRAG_OFFSET_MASK) | (last ? 0 : IP6_FRAG_MORE_FLAG)));
frag_hdr->_identification = lwip_htonl(identification);
IP6H_NEXTH_SET(ip6hdr, IP6_NEXTH_FRAGMENT);
IP6H_PLEN_SET(ip6hdr, (u16_t)(cop + IP6_FRAG_HLEN));
/* No need for separate header pbuf - we allowed room for it in rambuf
* when allocated.
*/
IP6_FRAG_STATS_INC(ip6_frag.xmit);
netif->output_ip6(netif, rambuf, dest);
/* 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 - cop);
fragment_offset = (u16_t)(fragment_offset + cop);
}
return ERR_OK;
}
#endif /* LWIP_IPV6 && LWIP_IPV6_FRAG */