863 lines
28 KiB
C
863 lines
28 KiB
C
/**
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* @file
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* This is the IPv4 packet segmentation and reassembly implementation.
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*
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*/
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/*
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* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* This file is part of the lwIP TCP/IP stack.
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*
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* Author: Jani Monoses <jani@iv.ro>
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* Simon Goldschmidt
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* original reassembly code by Adam Dunkels <adam@sics.se>
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*
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*/
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#include "lwip/opt.h"
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#include "lwip/ip_frag.h"
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#include "lwip/def.h"
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#include "lwip/inet_chksum.h"
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#include "lwip/netif.h"
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#include "lwip/snmp.h"
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#include "lwip/stats.h"
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#include "lwip/icmp.h"
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#include <string.h>
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#if IP_REASSEMBLY
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/**
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* The IP reassembly code currently has the following limitations:
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* - IP header options are not supported
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* - fragments must not overlap (e.g. due to different routes),
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* currently, overlapping or duplicate fragments are thrown away
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* if IP_REASS_CHECK_OVERLAP=1 (the default)!
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*
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* @todo: work with IP header options
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*/
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/** Setting this to 0, you can turn off checking the fragments for overlapping
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* regions. The code gets a little smaller. Only use this if you know that
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* overlapping won't occur on your network! */
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#ifndef IP_REASS_CHECK_OVERLAP
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#define IP_REASS_CHECK_OVERLAP 1
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#endif /* IP_REASS_CHECK_OVERLAP */
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/** Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is
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* full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller.
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* Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA
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* is set to 1, so one datagram can be reassembled at a time, only. */
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#ifndef IP_REASS_FREE_OLDEST
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#define IP_REASS_FREE_OLDEST 1
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#endif /* IP_REASS_FREE_OLDEST */
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#define IP_REASS_FLAG_LASTFRAG 0x01
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/** This is a helper struct which holds the starting
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* offset and the ending offset of this fragment to
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* easily chain the fragments.
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* It has the same packing requirements as the IP header, since it replaces
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* the IP header in memory in incoming fragments (after copying it) to keep
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* track of the various fragments. (-> If the IP header doesn't need packing,
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* this struct doesn't need packing, too.)
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*/
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#ifdef PACK_STRUCT_USE_INCLUDES
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# include "arch/bpstruct.h"
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#endif
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PACK_STRUCT_BEGIN
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struct ip_reass_helper {
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PACK_STRUCT_FIELD(struct pbuf *next_pbuf);
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PACK_STRUCT_FIELD(u16_t start);
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PACK_STRUCT_FIELD(u16_t end);
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} PACK_STRUCT_STRUCT;
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PACK_STRUCT_END
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#ifdef PACK_STRUCT_USE_INCLUDES
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# include "arch/epstruct.h"
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#endif
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#define IP_ADDRESSES_AND_ID_MATCH(iphdrA, iphdrB) \
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(ip_addr_cmp(&(iphdrA)->src, &(iphdrB)->src) && \
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ip_addr_cmp(&(iphdrA)->dest, &(iphdrB)->dest) && \
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IPH_ID(iphdrA) == IPH_ID(iphdrB)) ? 1 : 0
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/* global variables */
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static struct ip_reassdata *reassdatagrams;
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static u16_t ip_reass_pbufcount;
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/* function prototypes */
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static void ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev);
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static int ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev);
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/**
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* Reassembly timer base function
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* for both NO_SYS == 0 and 1 (!).
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*
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* Should be called every 1000 msec (defined by IP_TMR_INTERVAL).
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*/
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void
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ip_reass_tmr(void)
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{
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struct ip_reassdata *r, *prev = NULL;
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r = reassdatagrams;
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while (r != NULL) {
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/* Decrement the timer. Once it reaches 0,
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* clean up the incomplete fragment assembly */
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if (r->timer > 0) {
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r->timer--;
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LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer dec %"U16_F"\n",(u16_t)r->timer));
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prev = r;
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r = r->next;
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} else {
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/* reassembly timed out */
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struct ip_reassdata *tmp;
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LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer timed out\n"));
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tmp = r;
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/* get the next pointer before freeing */
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r = r->next;
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/* free the helper struct and all enqueued pbufs */
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ip_reass_free_complete_datagram(tmp, prev);
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}
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}
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}
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/**
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* Free a datagram (struct ip_reassdata) and all its pbufs.
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* Updates the total count of enqueued pbufs (ip_reass_pbufcount),
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* SNMP counters and sends an ICMP time exceeded packet.
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*
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* @param ipr datagram to free
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* @param prev the previous datagram in the linked list
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* @return the number of pbufs freed
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*/
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static int
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ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev)
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{
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u16_t pbufs_freed = 0;
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u8_t clen;
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struct pbuf *p;
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struct ip_reass_helper *iprh;
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LWIP_ASSERT("prev != ipr", prev != ipr);
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if (prev != NULL) {
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LWIP_ASSERT("prev->next == ipr", prev->next == ipr);
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}
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snmp_inc_ipreasmfails();
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#if LWIP_ICMP
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iprh = (struct ip_reass_helper *)ipr->p->payload;
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if (iprh->start == 0) {
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/* The first fragment was received, send ICMP time exceeded. */
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/* First, de-queue the first pbuf from r->p. */
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p = ipr->p;
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ipr->p = iprh->next_pbuf;
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/* Then, copy the original header into it. */
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SMEMCPY(p->payload, &ipr->iphdr, IP_HLEN);
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icmp_time_exceeded(p, ICMP_TE_FRAG);
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clen = pbuf_clen(p);
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LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
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pbufs_freed += clen;
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pbuf_free(p);
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}
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#endif /* LWIP_ICMP */
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/* First, free all received pbufs. The individual pbufs need to be released
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separately as they have not yet been chained */
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p = ipr->p;
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while (p != NULL) {
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struct pbuf *pcur;
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iprh = (struct ip_reass_helper *)p->payload;
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pcur = p;
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/* get the next pointer before freeing */
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p = iprh->next_pbuf;
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clen = pbuf_clen(pcur);
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LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
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pbufs_freed += clen;
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pbuf_free(pcur);
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}
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/* Then, unchain the struct ip_reassdata from the list and free it. */
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ip_reass_dequeue_datagram(ipr, prev);
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LWIP_ASSERT("ip_reass_pbufcount >= clen", ip_reass_pbufcount >= pbufs_freed);
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ip_reass_pbufcount -= pbufs_freed;
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return pbufs_freed;
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}
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#if IP_REASS_FREE_OLDEST
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/**
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* Free the oldest datagram to make room for enqueueing new fragments.
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* The datagram 'fraghdr' belongs to is not freed!
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*
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* @param fraghdr IP header of the current fragment
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* @param pbufs_needed number of pbufs needed to enqueue
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* (used for freeing other datagrams if not enough space)
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* @return the number of pbufs freed
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*/
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static int
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ip_reass_remove_oldest_datagram(struct ip_hdr *fraghdr, int pbufs_needed)
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{
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/* @todo Can't we simply remove the last datagram in the
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* linked list behind reassdatagrams?
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*/
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struct ip_reassdata *r, *oldest, *prev;
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int pbufs_freed = 0, pbufs_freed_current;
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int other_datagrams;
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/* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs,
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* but don't free the datagram that 'fraghdr' belongs to! */
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do {
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oldest = NULL;
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prev = NULL;
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other_datagrams = 0;
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r = reassdatagrams;
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while (r != NULL) {
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if (!IP_ADDRESSES_AND_ID_MATCH(&r->iphdr, fraghdr)) {
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/* Not the same datagram as fraghdr */
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other_datagrams++;
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if (oldest == NULL) {
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oldest = r;
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} else if (r->timer <= oldest->timer) {
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/* older than the previous oldest */
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oldest = r;
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}
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}
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if (r->next != NULL) {
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prev = r;
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}
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r = r->next;
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}
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if (oldest != NULL) {
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pbufs_freed_current = ip_reass_free_complete_datagram(oldest, prev);
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pbufs_freed += pbufs_freed_current;
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}
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} while ((pbufs_freed < pbufs_needed) && (other_datagrams > 1));
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return pbufs_freed;
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}
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#endif /* IP_REASS_FREE_OLDEST */
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/**
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* Enqueues a new fragment into the fragment queue
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* @param fraghdr points to the new fragments IP hdr
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* @param clen number of pbufs needed to enqueue (used for freeing other datagrams if not enough space)
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* @return A pointer to the queue location into which the fragment was enqueued
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*/
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static struct ip_reassdata*
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ip_reass_enqueue_new_datagram(struct ip_hdr *fraghdr, int clen)
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{
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struct ip_reassdata* ipr;
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/* No matching previous fragment found, allocate a new reassdata struct */
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ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
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if (ipr == NULL) {
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#if IP_REASS_FREE_OLDEST
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if (ip_reass_remove_oldest_datagram(fraghdr, clen) >= clen) {
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ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
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}
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if (ipr == NULL)
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#endif /* IP_REASS_FREE_OLDEST */
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{
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IPFRAG_STATS_INC(ip_frag.memerr);
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LWIP_DEBUGF(IP_REASS_DEBUG,("Failed to alloc reassdata struct\n"));
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return NULL;
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}
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}
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memset(ipr, 0, sizeof(struct ip_reassdata));
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ipr->timer = IP_REASS_MAXAGE;
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/* enqueue the new structure to the front of the list */
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ipr->next = reassdatagrams;
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reassdatagrams = ipr;
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/* copy the ip header for later tests and input */
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/* @todo: no ip options supported? */
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SMEMCPY(&(ipr->iphdr), fraghdr, IP_HLEN);
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return ipr;
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}
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/**
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* Dequeues a datagram from the datagram queue. Doesn't deallocate the pbufs.
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* @param ipr points to the queue entry to dequeue
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*/
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static void
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ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev)
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{
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/* dequeue the reass struct */
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if (reassdatagrams == ipr) {
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/* it was the first in the list */
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reassdatagrams = ipr->next;
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} else {
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/* it wasn't the first, so it must have a valid 'prev' */
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LWIP_ASSERT("sanity check linked list", prev != NULL);
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prev->next = ipr->next;
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}
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/* now we can free the ip_reass struct */
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memp_free(MEMP_REASSDATA, ipr);
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}
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/**
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* Chain a new pbuf into the pbuf list that composes the datagram. The pbuf list
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* will grow over time as new pbufs are rx.
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* Also checks that the datagram passes basic continuity checks (if the last
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* fragment was received at least once).
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* @param root_p points to the 'root' pbuf for the current datagram being assembled.
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* @param new_p points to the pbuf for the current fragment
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* @return 0 if invalid, >0 otherwise
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*/
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static int
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ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct pbuf *new_p)
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{
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struct ip_reass_helper *iprh, *iprh_tmp, *iprh_prev=NULL;
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struct pbuf *q;
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u16_t offset,len;
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struct ip_hdr *fraghdr;
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int valid = 1;
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/* Extract length and fragment offset from current fragment */
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fraghdr = (struct ip_hdr*)new_p->payload;
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len = ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4;
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offset = (ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8;
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/* overwrite the fragment's ip header from the pbuf with our helper struct,
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* and setup the embedded helper structure. */
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/* make sure the struct ip_reass_helper fits into the IP header */
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LWIP_ASSERT("sizeof(struct ip_reass_helper) <= IP_HLEN",
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sizeof(struct ip_reass_helper) <= IP_HLEN);
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iprh = (struct ip_reass_helper*)new_p->payload;
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iprh->next_pbuf = NULL;
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iprh->start = offset;
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iprh->end = offset + len;
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/* Iterate through until we either get to the end of the list (append),
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* or we find on with a larger offset (insert). */
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for (q = ipr->p; q != NULL;) {
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iprh_tmp = (struct ip_reass_helper*)q->payload;
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if (iprh->start < iprh_tmp->start) {
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/* the new pbuf should be inserted before this */
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iprh->next_pbuf = q;
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if (iprh_prev != NULL) {
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/* not the fragment with the lowest offset */
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#if IP_REASS_CHECK_OVERLAP
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if ((iprh->start < iprh_prev->end) || (iprh->end > iprh_tmp->start)) {
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/* fragment overlaps with previous or following, throw away */
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goto freepbuf;
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}
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#endif /* IP_REASS_CHECK_OVERLAP */
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iprh_prev->next_pbuf = new_p;
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} else {
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/* fragment with the lowest offset */
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ipr->p = new_p;
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}
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break;
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} else if(iprh->start == iprh_tmp->start) {
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/* received the same datagram twice: no need to keep the datagram */
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goto freepbuf;
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#if IP_REASS_CHECK_OVERLAP
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} else if(iprh->start < iprh_tmp->end) {
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/* overlap: no need to keep the new datagram */
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goto freepbuf;
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#endif /* IP_REASS_CHECK_OVERLAP */
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} else {
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/* Check if the fragments received so far have no wholes. */
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if (iprh_prev != NULL) {
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if (iprh_prev->end != iprh_tmp->start) {
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/* There is a fragment missing between the current
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* and the previous fragment */
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valid = 0;
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}
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}
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}
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q = iprh_tmp->next_pbuf;
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iprh_prev = iprh_tmp;
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}
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/* If q is NULL, then we made it to the end of the list. Determine what to do now */
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if (q == NULL) {
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if (iprh_prev != NULL) {
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/* this is (for now), the fragment with the highest offset:
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* chain it to the last fragment */
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#if IP_REASS_CHECK_OVERLAP
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LWIP_ASSERT("check fragments don't overlap", iprh_prev->end <= iprh->start);
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#endif /* IP_REASS_CHECK_OVERLAP */
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iprh_prev->next_pbuf = new_p;
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if (iprh_prev->end != iprh->start) {
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valid = 0;
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}
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} else {
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#if IP_REASS_CHECK_OVERLAP
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LWIP_ASSERT("no previous fragment, this must be the first fragment!",
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ipr->p == NULL);
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#endif /* IP_REASS_CHECK_OVERLAP */
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/* this is the first fragment we ever received for this ip datagram */
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ipr->p = new_p;
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}
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}
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/* At this point, the validation part begins: */
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/* If we already received the last fragment */
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if ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0) {
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/* and had no wholes so far */
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if (valid) {
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/* then check if the rest of the fragments is here */
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/* Check if the queue starts with the first datagram */
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if (((struct ip_reass_helper*)ipr->p->payload)->start != 0) {
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valid = 0;
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} else {
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/* and check that there are no wholes after this datagram */
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iprh_prev = iprh;
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q = iprh->next_pbuf;
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while (q != NULL) {
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iprh = (struct ip_reass_helper*)q->payload;
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if (iprh_prev->end != iprh->start) {
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valid = 0;
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break;
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}
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iprh_prev = iprh;
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q = iprh->next_pbuf;
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}
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/* if still valid, all fragments are received
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* (because to the MF==0 already arrived */
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if (valid) {
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LWIP_ASSERT("sanity check", ipr->p != NULL);
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LWIP_ASSERT("sanity check",
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((struct ip_reass_helper*)ipr->p->payload) != iprh);
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LWIP_ASSERT("validate_datagram:next_pbuf!=NULL",
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iprh->next_pbuf == NULL);
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LWIP_ASSERT("validate_datagram:datagram end!=datagram len",
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iprh->end == ipr->datagram_len);
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}
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}
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}
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/* If valid is 0 here, there are some fragments missing in the middle
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* (since MF == 0 has already arrived). Such datagrams simply time out if
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* no more fragments are received... */
|
|
return valid;
|
|
}
|
|
/* If we come here, not all fragments were received, yet! */
|
|
return 0; /* not yet valid! */
|
|
#if IP_REASS_CHECK_OVERLAP
|
|
freepbuf:
|
|
ip_reass_pbufcount -= pbuf_clen(new_p);
|
|
pbuf_free(new_p);
|
|
return 0;
|
|
#endif /* IP_REASS_CHECK_OVERLAP */
|
|
}
|
|
|
|
/**
|
|
* 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 *
|
|
ip_reass(struct pbuf *p)
|
|
{
|
|
struct pbuf *r;
|
|
struct ip_hdr *fraghdr;
|
|
struct ip_reassdata *ipr;
|
|
struct ip_reass_helper *iprh;
|
|
u16_t offset, len;
|
|
u8_t clen;
|
|
struct ip_reassdata *ipr_prev = NULL;
|
|
|
|
IPFRAG_STATS_INC(ip_frag.recv);
|
|
snmp_inc_ipreasmreqds();
|
|
|
|
fraghdr = (struct ip_hdr*)p->payload;
|
|
|
|
if ((IPH_HL(fraghdr) * 4) != IP_HLEN) {
|
|
LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: IP options currently not supported!\n"));
|
|
IPFRAG_STATS_INC(ip_frag.err);
|
|
goto nullreturn;
|
|
}
|
|
|
|
offset = (ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8;
|
|
len = ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4;
|
|
|
|
/* 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,("ip_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, ("ip_reass: matching previous fragment ID=%"X16_F"\n",
|
|
ntohs(IPH_ID(fraghdr))));
|
|
IPFRAG_STATS_INC(ip_frag.cachehit);
|
|
break;
|
|
}
|
|
ipr_prev = ipr;
|
|
}
|
|
|
|
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 (((ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) == 0) &&
|
|
((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);
|
|
}
|
|
}
|
|
/* 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 */
|
|
ip_reass_pbufcount += clen;
|
|
|
|
/* 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*/
|
|
if ((IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0) {
|
|
ipr->flags |= IP_REASS_FLAG_LASTFRAG;
|
|
ipr->datagram_len = offset + len;
|
|
LWIP_DEBUGF(IP_REASS_DEBUG,
|
|
("ip_reass: last fragment seen, total len %"S16_F"\n",
|
|
ipr->datagram_len));
|
|
}
|
|
/* find the right place to insert this pbuf */
|
|
/* @todo: trim pbufs if fragments are overlapping */
|
|
if (ip_reass_chain_frag_into_datagram_and_validate(ipr, p)) {
|
|
/* the totally last fragment (flag more fragments = 0) was received at least
|
|
* once AND all fragments are received */
|
|
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, htons(ipr->datagram_len));
|
|
IPH_OFFSET_SET(fraghdr, 0);
|
|
IPH_CHKSUM_SET(fraghdr, 0);
|
|
/* @todo: do we need to set calculate the correct checksum? */
|
|
IPH_CHKSUM_SET(fraghdr, inet_chksum(fraghdr, IP_HLEN));
|
|
|
|
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 succeding fragment */
|
|
pbuf_header(r, -IP_HLEN);
|
|
pbuf_cat(p, r);
|
|
r = iprh->next_pbuf;
|
|
}
|
|
/* 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. */
|
|
ip_reass_pbufcount -= pbuf_clen(p);
|
|
|
|
/* 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:
|
|
LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: nullreturn\n"));
|
|
IPFRAG_STATS_INC(ip_frag.drop);
|
|
pbuf_free(p);
|
|
return NULL;
|
|
}
|
|
#endif /* IP_REASSEMBLY */
|
|
|
|
#if IP_FRAG
|
|
#if IP_FRAG_USES_STATIC_BUF
|
|
static u8_t buf[LWIP_MEM_ALIGN_SIZE(IP_FRAG_MAX_MTU + MEM_ALIGNMENT - 1)];
|
|
#else /* IP_FRAG_USES_STATIC_BUF */
|
|
|
|
#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 */
|
|
#endif /* IP_FRAG_USES_STATIC_BUF */
|
|
|
|
/**
|
|
* Fragment an IP datagram if too large for the netif.
|
|
*
|
|
* Chop the datagram in MTU sized chunks and send them in order
|
|
* by using a fixed size static memory buffer (PBUF_REF) or
|
|
* point PBUF_REFs into p (depending on IP_FRAG_USES_STATIC_BUF).
|
|
*
|
|
* @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
|
|
ip_frag(struct pbuf *p, struct netif *netif, ip_addr_t *dest)
|
|
{
|
|
struct pbuf *rambuf;
|
|
#if IP_FRAG_USES_STATIC_BUF
|
|
struct pbuf *header;
|
|
#else
|
|
#if !LWIP_NETIF_TX_SINGLE_PBUF
|
|
struct pbuf *newpbuf;
|
|
#endif
|
|
struct ip_hdr *original_iphdr;
|
|
#endif
|
|
struct ip_hdr *iphdr;
|
|
u16_t nfb;
|
|
u16_t left, cop;
|
|
u16_t mtu = netif->mtu;
|
|
u16_t ofo, omf;
|
|
u16_t last;
|
|
u16_t poff = IP_HLEN;
|
|
u16_t tmp;
|
|
#if !IP_FRAG_USES_STATIC_BUF && !LWIP_NETIF_TX_SINGLE_PBUF
|
|
u16_t newpbuflen = 0;
|
|
u16_t left_to_copy;
|
|
#endif
|
|
|
|
/* Get a RAM based MTU sized pbuf */
|
|
#if IP_FRAG_USES_STATIC_BUF
|
|
/* When using a static buffer, we use a PBUF_REF, which we will
|
|
* use to reference the packet (without link header).
|
|
* Layer and length is irrelevant.
|
|
*/
|
|
rambuf = pbuf_alloc(PBUF_LINK, 0, PBUF_REF);
|
|
if (rambuf == NULL) {
|
|
LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc(PBUF_LINK, 0, PBUF_REF) failed\n"));
|
|
return ERR_MEM;
|
|
}
|
|
rambuf->tot_len = rambuf->len = mtu;
|
|
rambuf->payload = LWIP_MEM_ALIGN((void *)buf);
|
|
|
|
/* Copy the IP header in it */
|
|
iphdr = (struct ip_hdr *)rambuf->payload;
|
|
SMEMCPY(iphdr, p->payload, IP_HLEN);
|
|
#else /* IP_FRAG_USES_STATIC_BUF */
|
|
original_iphdr = (struct ip_hdr *)p->payload;
|
|
iphdr = original_iphdr;
|
|
#endif /* IP_FRAG_USES_STATIC_BUF */
|
|
|
|
/* Save original offset */
|
|
tmp = ntohs(IPH_OFFSET(iphdr));
|
|
ofo = tmp & IP_OFFMASK;
|
|
omf = tmp & IP_MF;
|
|
|
|
left = p->tot_len - IP_HLEN;
|
|
|
|
nfb = (mtu - IP_HLEN) / 8;
|
|
|
|
while (left) {
|
|
last = (left <= mtu - IP_HLEN);
|
|
|
|
/* Set new offset and MF flag */
|
|
tmp = omf | (IP_OFFMASK & (ofo));
|
|
if (!last) {
|
|
tmp = tmp | IP_MF;
|
|
}
|
|
|
|
/* Fill this fragment */
|
|
cop = last ? left : nfb * 8;
|
|
|
|
#if IP_FRAG_USES_STATIC_BUF
|
|
poff += pbuf_copy_partial(p, (u8_t*)iphdr + IP_HLEN, cop, poff);
|
|
#else /* IP_FRAG_USES_STATIC_BUF */
|
|
#if LWIP_NETIF_TX_SINGLE_PBUF
|
|
rambuf = pbuf_alloc(PBUF_IP, cop, PBUF_RAM);
|
|
if (rambuf == NULL) {
|
|
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, rambuf->payload, cop, poff);
|
|
/* make room for the IP header */
|
|
if(pbuf_header(rambuf, IP_HLEN)) {
|
|
pbuf_free(rambuf);
|
|
return ERR_MEM;
|
|
}
|
|
/* fill in the IP header */
|
|
SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
|
|
iphdr = 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) {
|
|
return ERR_MEM;
|
|
}
|
|
LWIP_ASSERT("this needs a pbuf in one piece!",
|
|
(p->len >= (IP_HLEN)));
|
|
SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
|
|
iphdr = (struct ip_hdr *)rambuf->payload;
|
|
|
|
/* Can just adjust p directly for needed offset. */
|
|
p->payload = (u8_t *)p->payload + poff;
|
|
p->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 = ip_frag_alloc_pbuf_custom_ref();
|
|
if (pcr == NULL) {
|
|
pbuf_free(rambuf);
|
|
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) {
|
|
ip_frag_free_pbuf_custom_ref(pcr);
|
|
pbuf_free(rambuf);
|
|
return ERR_MEM;
|
|
}
|
|
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 -= newpbuflen;
|
|
if (left_to_copy) {
|
|
p = p->next;
|
|
}
|
|
}
|
|
poff = newpbuflen;
|
|
#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
|
|
#endif /* IP_FRAG_USES_STATIC_BUF */
|
|
|
|
/* Correct header */
|
|
IPH_OFFSET_SET(iphdr, htons(tmp));
|
|
IPH_LEN_SET(iphdr, htons(cop + IP_HLEN));
|
|
IPH_CHKSUM_SET(iphdr, 0);
|
|
IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
|
|
|
|
#if IP_FRAG_USES_STATIC_BUF
|
|
if (last) {
|
|
pbuf_realloc(rambuf, left + IP_HLEN);
|
|
}
|
|
|
|
/* This part is ugly: we alloc a RAM based pbuf for
|
|
* the link level header for each chunk and then
|
|
* free it.A PBUF_ROM style pbuf for which pbuf_header
|
|
* worked would make things simpler.
|
|
*/
|
|
header = pbuf_alloc(PBUF_LINK, 0, PBUF_RAM);
|
|
if (header != NULL) {
|
|
pbuf_chain(header, rambuf);
|
|
netif->output(netif, header, dest);
|
|
IPFRAG_STATS_INC(ip_frag.xmit);
|
|
snmp_inc_ipfragcreates();
|
|
pbuf_free(header);
|
|
} else {
|
|
LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc() for header failed\n"));
|
|
pbuf_free(rambuf);
|
|
return ERR_MEM;
|
|
}
|
|
#else /* IP_FRAG_USES_STATIC_BUF */
|
|
/* 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);
|
|
#endif /* IP_FRAG_USES_STATIC_BUF */
|
|
left -= cop;
|
|
ofo += nfb;
|
|
}
|
|
#if IP_FRAG_USES_STATIC_BUF
|
|
pbuf_free(rambuf);
|
|
#endif /* IP_FRAG_USES_STATIC_BUF */
|
|
snmp_inc_ipfragoks();
|
|
return ERR_OK;
|
|
}
|
|
#endif /* IP_FRAG */
|