[457] | 1 | /**
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| 2 | * @file
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| 3 | * This is the IPv4 packet segmentation and reassembly implementation.
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| 4 | *
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| 5 | */
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| 6 |
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| 7 | /*
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| 8 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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| 9 | * All rights reserved.
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| 10 | *
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| 11 | * Redistribution and use in source and binary forms, with or without modification,
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| 12 | * are permitted provided that the following conditions are met:
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| 13 | *
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| 14 | * 1. Redistributions of source code must retain the above copyright notice,
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| 15 | * this list of conditions and the following disclaimer.
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| 16 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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| 17 | * this list of conditions and the following disclaimer in the documentation
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| 18 | * and/or other materials provided with the distribution.
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| 19 | * 3. The name of the author may not be used to endorse or promote products
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| 20 | * derived from this software without specific prior written permission.
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| 21 | *
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| 22 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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| 23 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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| 24 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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| 25 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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| 26 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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| 27 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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| 28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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| 29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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| 30 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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| 31 | * OF SUCH DAMAGE.
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| 32 | *
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| 33 | * This file is part of the lwIP TCP/IP stack.
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| 34 | *
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| 35 | * Author: Jani Monoses <jani@iv.ro>
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| 36 | * Simon Goldschmidt
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| 37 | * original reassembly code by Adam Dunkels <adam@sics.se>
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| 38 | *
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| 39 | */
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| 40 |
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| 41 | #include "lwip/opt.h"
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| 42 |
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| 43 | #if LWIP_IPV4
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| 44 |
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| 45 | #include "lwip/ip4_frag.h"
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| 46 | #include "lwip/def.h"
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| 47 | #include "lwip/inet_chksum.h"
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| 48 | #include "lwip/netif.h"
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| 49 | #include "lwip/stats.h"
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| 50 | #include "lwip/icmp.h"
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| 51 |
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| 52 | #include <string.h>
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| 53 |
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| 54 | #if IP_REASSEMBLY
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| 55 | /**
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| 56 | * The IP reassembly code currently has the following limitations:
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| 57 | * - IP header options are not supported
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| 58 | * - fragments must not overlap (e.g. due to different routes),
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| 59 | * currently, overlapping or duplicate fragments are thrown away
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| 60 | * if IP_REASS_CHECK_OVERLAP=1 (the default)!
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| 61 | *
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| 62 | * @todo: work with IP header options
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| 63 | */
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| 64 |
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| 65 | /** Setting this to 0, you can turn off checking the fragments for overlapping
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| 66 | * regions. The code gets a little smaller. Only use this if you know that
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| 67 | * overlapping won't occur on your network! */
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| 68 | #ifndef IP_REASS_CHECK_OVERLAP
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| 69 | #define IP_REASS_CHECK_OVERLAP 1
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| 70 | #endif /* IP_REASS_CHECK_OVERLAP */
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| 71 |
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| 72 | /** Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is
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| 73 | * full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller.
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| 74 | * Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA
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| 75 | * is set to 1, so one datagram can be reassembled at a time, only. */
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| 76 | #ifndef IP_REASS_FREE_OLDEST
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| 77 | #define IP_REASS_FREE_OLDEST 1
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| 78 | #endif /* IP_REASS_FREE_OLDEST */
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| 79 |
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| 80 | #define IP_REASS_FLAG_LASTFRAG 0x01
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| 81 |
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| 82 | #define IP_REASS_VALIDATE_TELEGRAM_FINISHED 1
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| 83 | #define IP_REASS_VALIDATE_PBUF_QUEUED 0
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| 84 | #define IP_REASS_VALIDATE_PBUF_DROPPED -1
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| 85 |
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| 86 | /** This is a helper struct which holds the starting
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| 87 | * offset and the ending offset of this fragment to
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| 88 | * easily chain the fragments.
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| 89 | * It has the same packing requirements as the IP header, since it replaces
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| 90 | * the IP header in memory in incoming fragments (after copying it) to keep
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| 91 | * track of the various fragments. (-> If the IP header doesn't need packing,
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| 92 | * this struct doesn't need packing, too.)
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| 93 | */
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| 94 | #ifdef PACK_STRUCT_USE_INCLUDES
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| 95 | # include "arch/bpstruct.h"
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| 96 | #endif
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| 97 | PACK_STRUCT_BEGIN
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| 98 | struct ip_reass_helper {
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| 99 | PACK_STRUCT_FIELD(struct pbuf *next_pbuf);
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| 100 | PACK_STRUCT_FIELD(u16_t start);
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| 101 | PACK_STRUCT_FIELD(u16_t end);
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| 102 | } PACK_STRUCT_STRUCT;
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| 103 | PACK_STRUCT_END
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| 104 | #ifdef PACK_STRUCT_USE_INCLUDES
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| 105 | # include "arch/epstruct.h"
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| 106 | #endif
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| 107 |
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| 108 | #define IP_ADDRESSES_AND_ID_MATCH(iphdrA, iphdrB) \
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| 109 | (ip4_addr_cmp(&(iphdrA)->src, &(iphdrB)->src) && \
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| 110 | ip4_addr_cmp(&(iphdrA)->dest, &(iphdrB)->dest) && \
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| 111 | IPH_ID(iphdrA) == IPH_ID(iphdrB)) ? 1 : 0
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| 112 |
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| 113 | /* global variables */
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| 114 | static struct ip_reassdata *reassdatagrams;
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| 115 | static u16_t ip_reass_pbufcount;
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| 116 |
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| 117 | /* function prototypes */
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| 118 | static void ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev);
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| 119 | static int ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev);
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| 120 |
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| 121 | /**
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| 122 | * Reassembly timer base function
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| 123 | * for both NO_SYS == 0 and 1 (!).
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| 124 | *
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| 125 | * Should be called every 1000 msec (defined by IP_TMR_INTERVAL).
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| 126 | */
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| 127 | void
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| 128 | ip_reass_tmr(void)
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| 129 | {
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| 130 | struct ip_reassdata *r, *prev = NULL;
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| 131 |
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| 132 | r = reassdatagrams;
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| 133 | while (r != NULL) {
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| 134 | /* Decrement the timer. Once it reaches 0,
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| 135 | * clean up the incomplete fragment assembly */
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| 136 | if (r->timer > 0) {
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| 137 | r->timer--;
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| 138 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer dec %"U16_F"\n", (u16_t)r->timer));
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| 139 | prev = r;
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| 140 | r = r->next;
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| 141 | } else {
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| 142 | /* reassembly timed out */
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| 143 | struct ip_reassdata *tmp;
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| 144 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer timed out\n"));
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| 145 | tmp = r;
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| 146 | /* get the next pointer before freeing */
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| 147 | r = r->next;
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| 148 | /* free the helper struct and all enqueued pbufs */
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| 149 | ip_reass_free_complete_datagram(tmp, prev);
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| 150 | }
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| 151 | }
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| 152 | }
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| 153 |
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| 154 | /**
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| 155 | * Free a datagram (struct ip_reassdata) and all its pbufs.
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| 156 | * Updates the total count of enqueued pbufs (ip_reass_pbufcount),
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| 157 | * SNMP counters and sends an ICMP time exceeded packet.
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| 158 | *
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| 159 | * @param ipr datagram to free
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| 160 | * @param prev the previous datagram in the linked list
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| 161 | * @return the number of pbufs freed
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| 162 | */
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| 163 | static int
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| 164 | ip_reass_free_complete_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev)
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| 165 | {
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| 166 | u16_t pbufs_freed = 0;
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| 167 | u16_t clen;
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| 168 | struct pbuf *p;
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| 169 | struct ip_reass_helper *iprh;
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| 170 |
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| 171 | LWIP_ASSERT("prev != ipr", prev != ipr);
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| 172 | if (prev != NULL) {
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| 173 | LWIP_ASSERT("prev->next == ipr", prev->next == ipr);
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| 174 | }
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| 175 |
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| 176 | MIB2_STATS_INC(mib2.ipreasmfails);
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| 177 | #if LWIP_ICMP
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| 178 | iprh = (struct ip_reass_helper *)ipr->p->payload;
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| 179 | if (iprh->start == 0) {
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| 180 | /* The first fragment was received, send ICMP time exceeded. */
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| 181 | /* First, de-queue the first pbuf from r->p. */
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| 182 | p = ipr->p;
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| 183 | ipr->p = iprh->next_pbuf;
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| 184 | /* Then, copy the original header into it. */
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| 185 | SMEMCPY(p->payload, &ipr->iphdr, IP_HLEN);
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| 186 | icmp_time_exceeded(p, ICMP_TE_FRAG);
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| 187 | clen = pbuf_clen(p);
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| 188 | LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
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| 189 | pbufs_freed = (u16_t)(pbufs_freed + clen);
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| 190 | pbuf_free(p);
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| 191 | }
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| 192 | #endif /* LWIP_ICMP */
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| 193 |
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| 194 | /* First, free all received pbufs. The individual pbufs need to be released
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| 195 | separately as they have not yet been chained */
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| 196 | p = ipr->p;
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| 197 | while (p != NULL) {
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| 198 | struct pbuf *pcur;
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| 199 | iprh = (struct ip_reass_helper *)p->payload;
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| 200 | pcur = p;
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| 201 | /* get the next pointer before freeing */
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| 202 | p = iprh->next_pbuf;
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| 203 | clen = pbuf_clen(pcur);
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| 204 | LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
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| 205 | pbufs_freed = (u16_t)(pbufs_freed + clen);
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| 206 | pbuf_free(pcur);
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| 207 | }
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| 208 | /* Then, unchain the struct ip_reassdata from the list and free it. */
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| 209 | ip_reass_dequeue_datagram(ipr, prev);
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| 210 | LWIP_ASSERT("ip_reass_pbufcount >= pbufs_freed", ip_reass_pbufcount >= pbufs_freed);
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| 211 | ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount - pbufs_freed);
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| 212 |
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| 213 | return pbufs_freed;
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| 214 | }
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| 215 |
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| 216 | #if IP_REASS_FREE_OLDEST
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| 217 | /**
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| 218 | * Free the oldest datagram to make room for enqueueing new fragments.
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| 219 | * The datagram 'fraghdr' belongs to is not freed!
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| 220 | *
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| 221 | * @param fraghdr IP header of the current fragment
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| 222 | * @param pbufs_needed number of pbufs needed to enqueue
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| 223 | * (used for freeing other datagrams if not enough space)
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| 224 | * @return the number of pbufs freed
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| 225 | */
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| 226 | static int
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| 227 | ip_reass_remove_oldest_datagram(struct ip_hdr *fraghdr, int pbufs_needed)
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| 228 | {
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| 229 | /* @todo Can't we simply remove the last datagram in the
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| 230 | * linked list behind reassdatagrams?
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| 231 | */
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| 232 | struct ip_reassdata *r, *oldest, *prev, *oldest_prev;
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| 233 | int pbufs_freed = 0, pbufs_freed_current;
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| 234 | int other_datagrams;
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| 235 |
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| 236 | /* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs,
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| 237 | * but don't free the datagram that 'fraghdr' belongs to! */
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| 238 | do {
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| 239 | oldest = NULL;
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| 240 | prev = NULL;
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| 241 | oldest_prev = NULL;
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| 242 | other_datagrams = 0;
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| 243 | r = reassdatagrams;
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| 244 | while (r != NULL) {
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| 245 | if (!IP_ADDRESSES_AND_ID_MATCH(&r->iphdr, fraghdr)) {
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| 246 | /* Not the same datagram as fraghdr */
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| 247 | other_datagrams++;
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| 248 | if (oldest == NULL) {
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| 249 | oldest = r;
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| 250 | oldest_prev = prev;
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| 251 | } else if (r->timer <= oldest->timer) {
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| 252 | /* older than the previous oldest */
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| 253 | oldest = r;
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| 254 | oldest_prev = prev;
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| 255 | }
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| 256 | }
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| 257 | if (r->next != NULL) {
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| 258 | prev = r;
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| 259 | }
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| 260 | r = r->next;
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| 261 | }
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| 262 | if (oldest != NULL) {
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| 263 | pbufs_freed_current = ip_reass_free_complete_datagram(oldest, oldest_prev);
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| 264 | pbufs_freed += pbufs_freed_current;
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| 265 | }
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| 266 | } while ((pbufs_freed < pbufs_needed) && (other_datagrams > 1));
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| 267 | return pbufs_freed;
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| 268 | }
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| 269 | #endif /* IP_REASS_FREE_OLDEST */
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| 270 |
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| 271 | /**
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| 272 | * Enqueues a new fragment into the fragment queue
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| 273 | * @param fraghdr points to the new fragments IP hdr
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| 274 | * @param clen number of pbufs needed to enqueue (used for freeing other datagrams if not enough space)
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| 275 | * @return A pointer to the queue location into which the fragment was enqueued
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| 276 | */
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| 277 | static struct ip_reassdata *
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| 278 | ip_reass_enqueue_new_datagram(struct ip_hdr *fraghdr, int clen)
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| 279 | {
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| 280 | struct ip_reassdata *ipr;
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| 281 | #if ! IP_REASS_FREE_OLDEST
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| 282 | LWIP_UNUSED_ARG(clen);
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| 283 | #endif
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| 284 |
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| 285 | /* No matching previous fragment found, allocate a new reassdata struct */
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| 286 | ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
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| 287 | if (ipr == NULL) {
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| 288 | #if IP_REASS_FREE_OLDEST
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| 289 | if (ip_reass_remove_oldest_datagram(fraghdr, clen) >= clen) {
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| 290 | ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
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| 291 | }
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| 292 | if (ipr == NULL)
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| 293 | #endif /* IP_REASS_FREE_OLDEST */
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| 294 | {
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| 295 | IPFRAG_STATS_INC(ip_frag.memerr);
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| 296 | LWIP_DEBUGF(IP_REASS_DEBUG, ("Failed to alloc reassdata struct\n"));
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| 297 | return NULL;
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| 298 | }
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| 299 | }
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| 300 | memset(ipr, 0, sizeof(struct ip_reassdata));
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| 301 | ipr->timer = IP_REASS_MAXAGE;
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| 302 |
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| 303 | /* enqueue the new structure to the front of the list */
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| 304 | ipr->next = reassdatagrams;
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| 305 | reassdatagrams = ipr;
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| 306 | /* copy the ip header for later tests and input */
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| 307 | /* @todo: no ip options supported? */
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| 308 | SMEMCPY(&(ipr->iphdr), fraghdr, IP_HLEN);
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| 309 | return ipr;
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| 310 | }
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| 311 |
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| 312 | /**
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| 313 | * Dequeues a datagram from the datagram queue. Doesn't deallocate the pbufs.
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| 314 | * @param ipr points to the queue entry to dequeue
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| 315 | */
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| 316 | static void
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| 317 | ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev)
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| 318 | {
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| 319 | /* dequeue the reass struct */
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| 320 | if (reassdatagrams == ipr) {
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| 321 | /* it was the first in the list */
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| 322 | reassdatagrams = ipr->next;
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| 323 | } else {
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| 324 | /* it wasn't the first, so it must have a valid 'prev' */
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| 325 | LWIP_ASSERT("sanity check linked list", prev != NULL);
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| 326 | prev->next = ipr->next;
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| 327 | }
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| 328 |
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| 329 | /* now we can free the ip_reassdata struct */
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| 330 | memp_free(MEMP_REASSDATA, ipr);
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| 331 | }
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| 332 |
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| 333 | /**
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| 334 | * Chain a new pbuf into the pbuf list that composes the datagram. The pbuf list
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| 335 | * will grow over time as new pbufs are rx.
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| 336 | * Also checks that the datagram passes basic continuity checks (if the last
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| 337 | * fragment was received at least once).
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| 338 | * @param ipr points to the reassembly state
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| 339 | * @param new_p points to the pbuf for the current fragment
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| 340 | * @param is_last is 1 if this pbuf has MF==0 (ipr->flags not updated yet)
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| 341 | * @return see IP_REASS_VALIDATE_* defines
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| 342 | */
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| 343 | static int
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| 344 | ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct pbuf *new_p, int is_last)
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| 345 | {
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| 346 | struct ip_reass_helper *iprh, *iprh_tmp, *iprh_prev = NULL;
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| 347 | struct pbuf *q;
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| 348 | u16_t offset, len;
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| 349 | u8_t hlen;
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| 350 | struct ip_hdr *fraghdr;
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| 351 | int valid = 1;
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| 352 |
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| 353 | /* Extract length and fragment offset from current fragment */
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| 354 | fraghdr = (struct ip_hdr *)new_p->payload;
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| 355 | len = lwip_ntohs(IPH_LEN(fraghdr));
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| 356 | hlen = IPH_HL_BYTES(fraghdr);
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| 357 | if (hlen > len) {
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| 358 | /* invalid datagram */
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| 359 | return IP_REASS_VALIDATE_PBUF_DROPPED;
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| 360 | }
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| 361 | len = (u16_t)(len - hlen);
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| 362 | offset = IPH_OFFSET_BYTES(fraghdr);
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| 363 |
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| 364 | /* overwrite the fragment's ip header from the pbuf with our helper struct,
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| 365 | * and setup the embedded helper structure. */
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| 366 | /* make sure the struct ip_reass_helper fits into the IP header */
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| 367 | LWIP_ASSERT("sizeof(struct ip_reass_helper) <= IP_HLEN",
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| 368 | sizeof(struct ip_reass_helper) <= IP_HLEN);
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| 369 | iprh = (struct ip_reass_helper *)new_p->payload;
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| 370 | iprh->next_pbuf = NULL;
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| 371 | iprh->start = offset;
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| 372 | iprh->end = (u16_t)(offset + len);
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| 373 | if (iprh->end < offset) {
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| 374 | /* u16_t overflow, cannot handle this */
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| 375 | return IP_REASS_VALIDATE_PBUF_DROPPED;
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| 376 | }
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| 377 |
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| 378 | /* Iterate through until we either get to the end of the list (append),
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| 379 | * or we find one with a larger offset (insert). */
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| 380 | for (q = ipr->p; q != NULL;) {
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| 381 | iprh_tmp = (struct ip_reass_helper *)q->payload;
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| 382 | if (iprh->start < iprh_tmp->start) {
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| 383 | /* the new pbuf should be inserted before this */
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| 384 | iprh->next_pbuf = q;
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| 385 | if (iprh_prev != NULL) {
|
---|
| 386 | /* not the fragment with the lowest offset */
|
---|
| 387 | #if IP_REASS_CHECK_OVERLAP
|
---|
| 388 | if ((iprh->start < iprh_prev->end) || (iprh->end > iprh_tmp->start)) {
|
---|
| 389 | /* fragment overlaps with previous or following, throw away */
|
---|
| 390 | return IP_REASS_VALIDATE_PBUF_DROPPED;
|
---|
| 391 | }
|
---|
| 392 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
| 393 | iprh_prev->next_pbuf = new_p;
|
---|
| 394 | if (iprh_prev->end != iprh->start) {
|
---|
| 395 | /* There is a fragment missing between the current
|
---|
| 396 | * and the previous fragment */
|
---|
| 397 | valid = 0;
|
---|
| 398 | }
|
---|
| 399 | } else {
|
---|
| 400 | #if IP_REASS_CHECK_OVERLAP
|
---|
| 401 | if (iprh->end > iprh_tmp->start) {
|
---|
| 402 | /* fragment overlaps with following, throw away */
|
---|
| 403 | return IP_REASS_VALIDATE_PBUF_DROPPED;
|
---|
| 404 | }
|
---|
| 405 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
| 406 | /* fragment with the lowest offset */
|
---|
| 407 | ipr->p = new_p;
|
---|
| 408 | }
|
---|
| 409 | break;
|
---|
| 410 | } else if (iprh->start == iprh_tmp->start) {
|
---|
| 411 | /* received the same datagram twice: no need to keep the datagram */
|
---|
| 412 | return IP_REASS_VALIDATE_PBUF_DROPPED;
|
---|
| 413 | #if IP_REASS_CHECK_OVERLAP
|
---|
| 414 | } else if (iprh->start < iprh_tmp->end) {
|
---|
| 415 | /* overlap: no need to keep the new datagram */
|
---|
| 416 | return IP_REASS_VALIDATE_PBUF_DROPPED;
|
---|
| 417 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
| 418 | } else {
|
---|
| 419 | /* Check if the fragments received so far have no holes. */
|
---|
| 420 | if (iprh_prev != NULL) {
|
---|
| 421 | if (iprh_prev->end != iprh_tmp->start) {
|
---|
| 422 | /* There is a fragment missing between the current
|
---|
| 423 | * and the previous fragment */
|
---|
| 424 | valid = 0;
|
---|
| 425 | }
|
---|
| 426 | }
|
---|
| 427 | }
|
---|
| 428 | q = iprh_tmp->next_pbuf;
|
---|
| 429 | iprh_prev = iprh_tmp;
|
---|
| 430 | }
|
---|
| 431 |
|
---|
| 432 | /* If q is NULL, then we made it to the end of the list. Determine what to do now */
|
---|
| 433 | if (q == NULL) {
|
---|
| 434 | if (iprh_prev != NULL) {
|
---|
| 435 | /* this is (for now), the fragment with the highest offset:
|
---|
| 436 | * chain it to the last fragment */
|
---|
| 437 | #if IP_REASS_CHECK_OVERLAP
|
---|
| 438 | LWIP_ASSERT("check fragments don't overlap", iprh_prev->end <= iprh->start);
|
---|
| 439 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
| 440 | iprh_prev->next_pbuf = new_p;
|
---|
| 441 | if (iprh_prev->end != iprh->start) {
|
---|
| 442 | valid = 0;
|
---|
| 443 | }
|
---|
| 444 | } else {
|
---|
| 445 | #if IP_REASS_CHECK_OVERLAP
|
---|
| 446 | LWIP_ASSERT("no previous fragment, this must be the first fragment!",
|
---|
| 447 | ipr->p == NULL);
|
---|
| 448 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
| 449 | /* this is the first fragment we ever received for this ip datagram */
|
---|
| 450 | ipr->p = new_p;
|
---|
| 451 | }
|
---|
| 452 | }
|
---|
| 453 |
|
---|
| 454 | /* At this point, the validation part begins: */
|
---|
| 455 | /* If we already received the last fragment */
|
---|
| 456 | if (is_last || ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0)) {
|
---|
| 457 | /* and had no holes so far */
|
---|
| 458 | if (valid) {
|
---|
| 459 | /* then check if the rest of the fragments is here */
|
---|
| 460 | /* Check if the queue starts with the first datagram */
|
---|
| 461 | if ((ipr->p == NULL) || (((struct ip_reass_helper *)ipr->p->payload)->start != 0)) {
|
---|
| 462 | valid = 0;
|
---|
| 463 | } else {
|
---|
| 464 | /* and check that there are no holes after this datagram */
|
---|
| 465 | iprh_prev = iprh;
|
---|
| 466 | q = iprh->next_pbuf;
|
---|
| 467 | while (q != NULL) {
|
---|
| 468 | iprh = (struct ip_reass_helper *)q->payload;
|
---|
| 469 | if (iprh_prev->end != iprh->start) {
|
---|
| 470 | valid = 0;
|
---|
| 471 | break;
|
---|
| 472 | }
|
---|
| 473 | iprh_prev = iprh;
|
---|
| 474 | q = iprh->next_pbuf;
|
---|
| 475 | }
|
---|
| 476 | /* if still valid, all fragments are received
|
---|
| 477 | * (because to the MF==0 already arrived */
|
---|
| 478 | if (valid) {
|
---|
| 479 | LWIP_ASSERT("sanity check", ipr->p != NULL);
|
---|
| 480 | LWIP_ASSERT("sanity check",
|
---|
| 481 | ((struct ip_reass_helper *)ipr->p->payload) != iprh);
|
---|
| 482 | LWIP_ASSERT("validate_datagram:next_pbuf!=NULL",
|
---|
| 483 | iprh->next_pbuf == NULL);
|
---|
| 484 | }
|
---|
| 485 | }
|
---|
| 486 | }
|
---|
| 487 | /* If valid is 0 here, there are some fragments missing in the middle
|
---|
| 488 | * (since MF == 0 has already arrived). Such datagrams simply time out if
|
---|
| 489 | * no more fragments are received... */
|
---|
| 490 | return valid ? IP_REASS_VALIDATE_TELEGRAM_FINISHED : IP_REASS_VALIDATE_PBUF_QUEUED;
|
---|
| 491 | }
|
---|
| 492 | /* If we come here, not all fragments were received, yet! */
|
---|
| 493 | return IP_REASS_VALIDATE_PBUF_QUEUED; /* not yet valid! */
|
---|
| 494 | }
|
---|
| 495 |
|
---|
| 496 | /**
|
---|
| 497 | * Reassembles incoming IP fragments into an IP datagram.
|
---|
| 498 | *
|
---|
| 499 | * @param p points to a pbuf chain of the fragment
|
---|
| 500 | * @return NULL if reassembly is incomplete, ? otherwise
|
---|
| 501 | */
|
---|
| 502 | struct pbuf *
|
---|
| 503 | ip4_reass(struct pbuf *p)
|
---|
| 504 | {
|
---|
| 505 | struct pbuf *r;
|
---|
| 506 | struct ip_hdr *fraghdr;
|
---|
| 507 | struct ip_reassdata *ipr;
|
---|
| 508 | struct ip_reass_helper *iprh;
|
---|
| 509 | u16_t offset, len, clen;
|
---|
| 510 | u8_t hlen;
|
---|
| 511 | int valid;
|
---|
| 512 | int is_last;
|
---|
| 513 |
|
---|
| 514 | IPFRAG_STATS_INC(ip_frag.recv);
|
---|
| 515 | MIB2_STATS_INC(mib2.ipreasmreqds);
|
---|
| 516 |
|
---|
| 517 | fraghdr = (struct ip_hdr *)p->payload;
|
---|
| 518 |
|
---|
| 519 | if (IPH_HL_BYTES(fraghdr) != IP_HLEN) {
|
---|
| 520 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: IP options currently not supported!\n"));
|
---|
| 521 | IPFRAG_STATS_INC(ip_frag.err);
|
---|
| 522 | goto nullreturn;
|
---|
| 523 | }
|
---|
| 524 |
|
---|
| 525 | offset = IPH_OFFSET_BYTES(fraghdr);
|
---|
| 526 | len = lwip_ntohs(IPH_LEN(fraghdr));
|
---|
| 527 | hlen = IPH_HL_BYTES(fraghdr);
|
---|
| 528 | if (hlen > len) {
|
---|
| 529 | /* invalid datagram */
|
---|
| 530 | goto nullreturn;
|
---|
| 531 | }
|
---|
| 532 | len = (u16_t)(len - hlen);
|
---|
| 533 |
|
---|
| 534 | /* Check if we are allowed to enqueue more datagrams. */
|
---|
| 535 | clen = pbuf_clen(p);
|
---|
| 536 | if ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS) {
|
---|
| 537 | #if IP_REASS_FREE_OLDEST
|
---|
| 538 | if (!ip_reass_remove_oldest_datagram(fraghdr, clen) ||
|
---|
| 539 | ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS))
|
---|
| 540 | #endif /* IP_REASS_FREE_OLDEST */
|
---|
| 541 | {
|
---|
| 542 | /* No datagram could be freed and still too many pbufs enqueued */
|
---|
| 543 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: Overflow condition: pbufct=%d, clen=%d, MAX=%d\n",
|
---|
| 544 | ip_reass_pbufcount, clen, IP_REASS_MAX_PBUFS));
|
---|
| 545 | IPFRAG_STATS_INC(ip_frag.memerr);
|
---|
| 546 | /* @todo: send ICMP time exceeded here? */
|
---|
| 547 | /* drop this pbuf */
|
---|
| 548 | goto nullreturn;
|
---|
| 549 | }
|
---|
| 550 | }
|
---|
| 551 |
|
---|
| 552 | /* Look for the datagram the fragment belongs to in the current datagram queue,
|
---|
| 553 | * remembering the previous in the queue for later dequeueing. */
|
---|
| 554 | for (ipr = reassdatagrams; ipr != NULL; ipr = ipr->next) {
|
---|
| 555 | /* Check if the incoming fragment matches the one currently present
|
---|
| 556 | in the reassembly buffer. If so, we proceed with copying the
|
---|
| 557 | fragment into the buffer. */
|
---|
| 558 | if (IP_ADDRESSES_AND_ID_MATCH(&ipr->iphdr, fraghdr)) {
|
---|
| 559 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: matching previous fragment ID=%"X16_F"\n",
|
---|
| 560 | lwip_ntohs(IPH_ID(fraghdr))));
|
---|
| 561 | IPFRAG_STATS_INC(ip_frag.cachehit);
|
---|
| 562 | break;
|
---|
| 563 | }
|
---|
| 564 | }
|
---|
| 565 |
|
---|
| 566 | if (ipr == NULL) {
|
---|
| 567 | /* Enqueue a new datagram into the datagram queue */
|
---|
| 568 | ipr = ip_reass_enqueue_new_datagram(fraghdr, clen);
|
---|
| 569 | /* Bail if unable to enqueue */
|
---|
| 570 | if (ipr == NULL) {
|
---|
| 571 | goto nullreturn;
|
---|
| 572 | }
|
---|
| 573 | } else {
|
---|
| 574 | if (((lwip_ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) == 0) &&
|
---|
| 575 | ((lwip_ntohs(IPH_OFFSET(&ipr->iphdr)) & IP_OFFMASK) != 0)) {
|
---|
| 576 | /* ipr->iphdr is not the header from the first fragment, but fraghdr is
|
---|
| 577 | * -> copy fraghdr into ipr->iphdr since we want to have the header
|
---|
| 578 | * of the first fragment (for ICMP time exceeded and later, for copying
|
---|
| 579 | * all options, if supported)*/
|
---|
| 580 | SMEMCPY(&ipr->iphdr, fraghdr, IP_HLEN);
|
---|
| 581 | }
|
---|
| 582 | }
|
---|
| 583 |
|
---|
| 584 | /* At this point, we have either created a new entry or pointing
|
---|
| 585 | * to an existing one */
|
---|
| 586 |
|
---|
| 587 | /* check for 'no more fragments', and update queue entry*/
|
---|
| 588 | is_last = (IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0;
|
---|
| 589 | if (is_last) {
|
---|
| 590 | u16_t datagram_len = (u16_t)(offset + len);
|
---|
| 591 | if ((datagram_len < offset) || (datagram_len > (0xFFFF - IP_HLEN))) {
|
---|
| 592 | /* u16_t overflow, cannot handle this */
|
---|
| 593 | goto nullreturn_ipr;
|
---|
| 594 | }
|
---|
| 595 | }
|
---|
| 596 | /* find the right place to insert this pbuf */
|
---|
| 597 | /* @todo: trim pbufs if fragments are overlapping */
|
---|
| 598 | valid = ip_reass_chain_frag_into_datagram_and_validate(ipr, p, is_last);
|
---|
| 599 | if (valid == IP_REASS_VALIDATE_PBUF_DROPPED) {
|
---|
| 600 | goto nullreturn_ipr;
|
---|
| 601 | }
|
---|
| 602 | /* if we come here, the pbuf has been enqueued */
|
---|
| 603 |
|
---|
| 604 | /* Track the current number of pbufs current 'in-flight', in order to limit
|
---|
| 605 | the number of fragments that may be enqueued at any one time
|
---|
| 606 | (overflow checked by testing against IP_REASS_MAX_PBUFS) */
|
---|
| 607 | ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount + clen);
|
---|
| 608 | if (is_last) {
|
---|
| 609 | u16_t datagram_len = (u16_t)(offset + len);
|
---|
| 610 | ipr->datagram_len = datagram_len;
|
---|
| 611 | ipr->flags |= IP_REASS_FLAG_LASTFRAG;
|
---|
| 612 | LWIP_DEBUGF(IP_REASS_DEBUG,
|
---|
| 613 | ("ip4_reass: last fragment seen, total len %"S16_F"\n",
|
---|
| 614 | ipr->datagram_len));
|
---|
| 615 | }
|
---|
| 616 |
|
---|
| 617 | if (valid == IP_REASS_VALIDATE_TELEGRAM_FINISHED) {
|
---|
| 618 | struct ip_reassdata *ipr_prev;
|
---|
| 619 | /* the totally last fragment (flag more fragments = 0) was received at least
|
---|
| 620 | * once AND all fragments are received */
|
---|
| 621 | u16_t datagram_len = (u16_t)(ipr->datagram_len + IP_HLEN);
|
---|
| 622 |
|
---|
| 623 | /* save the second pbuf before copying the header over the pointer */
|
---|
| 624 | r = ((struct ip_reass_helper *)ipr->p->payload)->next_pbuf;
|
---|
| 625 |
|
---|
| 626 | /* copy the original ip header back to the first pbuf */
|
---|
| 627 | fraghdr = (struct ip_hdr *)(ipr->p->payload);
|
---|
| 628 | SMEMCPY(fraghdr, &ipr->iphdr, IP_HLEN);
|
---|
| 629 | IPH_LEN_SET(fraghdr, lwip_htons(datagram_len));
|
---|
| 630 | IPH_OFFSET_SET(fraghdr, 0);
|
---|
| 631 | IPH_CHKSUM_SET(fraghdr, 0);
|
---|
| 632 | /* @todo: do we need to set/calculate the correct checksum? */
|
---|
| 633 | #if CHECKSUM_GEN_IP
|
---|
| 634 | IF__NETIF_CHECKSUM_ENABLED(ip_current_input_netif(), NETIF_CHECKSUM_GEN_IP) {
|
---|
| 635 | IPH_CHKSUM_SET(fraghdr, inet_chksum(fraghdr, IP_HLEN));
|
---|
| 636 | }
|
---|
| 637 | #endif /* CHECKSUM_GEN_IP */
|
---|
| 638 |
|
---|
| 639 | p = ipr->p;
|
---|
| 640 |
|
---|
| 641 | /* chain together the pbufs contained within the reass_data list. */
|
---|
| 642 | while (r != NULL) {
|
---|
| 643 | iprh = (struct ip_reass_helper *)r->payload;
|
---|
| 644 |
|
---|
| 645 | /* hide the ip header for every succeeding fragment */
|
---|
| 646 | pbuf_remove_header(r, IP_HLEN);
|
---|
| 647 | pbuf_cat(p, r);
|
---|
| 648 | r = iprh->next_pbuf;
|
---|
| 649 | }
|
---|
| 650 |
|
---|
| 651 | /* find the previous entry in the linked list */
|
---|
| 652 | if (ipr == reassdatagrams) {
|
---|
| 653 | ipr_prev = NULL;
|
---|
| 654 | } else {
|
---|
| 655 | for (ipr_prev = reassdatagrams; ipr_prev != NULL; ipr_prev = ipr_prev->next) {
|
---|
| 656 | if (ipr_prev->next == ipr) {
|
---|
| 657 | break;
|
---|
| 658 | }
|
---|
| 659 | }
|
---|
| 660 | }
|
---|
| 661 |
|
---|
| 662 | /* release the sources allocate for the fragment queue entry */
|
---|
| 663 | ip_reass_dequeue_datagram(ipr, ipr_prev);
|
---|
| 664 |
|
---|
| 665 | /* and adjust the number of pbufs currently queued for reassembly. */
|
---|
| 666 | clen = pbuf_clen(p);
|
---|
| 667 | LWIP_ASSERT("ip_reass_pbufcount >= clen", ip_reass_pbufcount >= clen);
|
---|
| 668 | ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount - clen);
|
---|
| 669 |
|
---|
| 670 | MIB2_STATS_INC(mib2.ipreasmoks);
|
---|
| 671 |
|
---|
| 672 | /* Return the pbuf chain */
|
---|
| 673 | return p;
|
---|
| 674 | }
|
---|
| 675 | /* the datagram is not (yet?) reassembled completely */
|
---|
| 676 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_pbufcount: %d out\n", ip_reass_pbufcount));
|
---|
| 677 | return NULL;
|
---|
| 678 |
|
---|
| 679 | nullreturn_ipr:
|
---|
| 680 | LWIP_ASSERT("ipr != NULL", ipr != NULL);
|
---|
| 681 | if (ipr->p == NULL) {
|
---|
| 682 | /* dropped pbuf after creating a new datagram entry: remove the entry, too */
|
---|
| 683 | LWIP_ASSERT("not firstalthough just enqueued", ipr == reassdatagrams);
|
---|
| 684 | ip_reass_dequeue_datagram(ipr, NULL);
|
---|
| 685 | }
|
---|
| 686 |
|
---|
| 687 | nullreturn:
|
---|
| 688 | LWIP_DEBUGF(IP_REASS_DEBUG, ("ip4_reass: nullreturn\n"));
|
---|
| 689 | IPFRAG_STATS_INC(ip_frag.drop);
|
---|
| 690 | pbuf_free(p);
|
---|
| 691 | return NULL;
|
---|
| 692 | }
|
---|
| 693 | #endif /* IP_REASSEMBLY */
|
---|
| 694 |
|
---|
| 695 | #if IP_FRAG
|
---|
| 696 | #if !LWIP_NETIF_TX_SINGLE_PBUF
|
---|
| 697 | /** Allocate a new struct pbuf_custom_ref */
|
---|
| 698 | static struct pbuf_custom_ref *
|
---|
| 699 | ip_frag_alloc_pbuf_custom_ref(void)
|
---|
| 700 | {
|
---|
| 701 | return (struct pbuf_custom_ref *)memp_malloc(MEMP_FRAG_PBUF);
|
---|
| 702 | }
|
---|
| 703 |
|
---|
| 704 | /** Free a struct pbuf_custom_ref */
|
---|
| 705 | static void
|
---|
| 706 | ip_frag_free_pbuf_custom_ref(struct pbuf_custom_ref *p)
|
---|
| 707 | {
|
---|
| 708 | LWIP_ASSERT("p != NULL", p != NULL);
|
---|
| 709 | memp_free(MEMP_FRAG_PBUF, p);
|
---|
| 710 | }
|
---|
| 711 |
|
---|
| 712 | /** Free-callback function to free a 'struct pbuf_custom_ref', called by
|
---|
| 713 | * pbuf_free. */
|
---|
| 714 | static void
|
---|
| 715 | ipfrag_free_pbuf_custom(struct pbuf *p)
|
---|
| 716 | {
|
---|
| 717 | struct pbuf_custom_ref *pcr = (struct pbuf_custom_ref *)p;
|
---|
| 718 | LWIP_ASSERT("pcr != NULL", pcr != NULL);
|
---|
| 719 | LWIP_ASSERT("pcr == p", (void *)pcr == (void *)p);
|
---|
| 720 | if (pcr->original != NULL) {
|
---|
| 721 | pbuf_free(pcr->original);
|
---|
| 722 | }
|
---|
| 723 | ip_frag_free_pbuf_custom_ref(pcr);
|
---|
| 724 | }
|
---|
| 725 | #endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
|
---|
| 726 |
|
---|
| 727 | /**
|
---|
| 728 | * Fragment an IP datagram if too large for the netif.
|
---|
| 729 | *
|
---|
| 730 | * Chop the datagram in MTU sized chunks and send them in order
|
---|
| 731 | * by pointing PBUF_REFs into p.
|
---|
| 732 | *
|
---|
| 733 | * @param p ip packet to send
|
---|
| 734 | * @param netif the netif on which to send
|
---|
| 735 | * @param dest destination ip address to which to send
|
---|
| 736 | *
|
---|
| 737 | * @return ERR_OK if sent successfully, err_t otherwise
|
---|
| 738 | */
|
---|
| 739 | err_t
|
---|
| 740 | ip4_frag(struct pbuf *p, struct netif *netif, const ip4_addr_t *dest)
|
---|
| 741 | {
|
---|
| 742 | struct pbuf *rambuf;
|
---|
| 743 | #if !LWIP_NETIF_TX_SINGLE_PBUF
|
---|
| 744 | struct pbuf *newpbuf;
|
---|
| 745 | u16_t newpbuflen = 0;
|
---|
| 746 | u16_t left_to_copy;
|
---|
| 747 | #endif
|
---|
| 748 | struct ip_hdr *original_iphdr;
|
---|
| 749 | struct ip_hdr *iphdr;
|
---|
| 750 | const u16_t nfb = (u16_t)((netif->mtu - IP_HLEN) / 8);
|
---|
| 751 | u16_t left, fragsize;
|
---|
| 752 | u16_t ofo;
|
---|
| 753 | int last;
|
---|
| 754 | u16_t poff = IP_HLEN;
|
---|
| 755 | u16_t tmp;
|
---|
| 756 | int mf_set;
|
---|
| 757 |
|
---|
| 758 | original_iphdr = (struct ip_hdr *)p->payload;
|
---|
| 759 | iphdr = original_iphdr;
|
---|
| 760 | if (IPH_HL_BYTES(iphdr) != IP_HLEN) {
|
---|
| 761 | /* ip4_frag() does not support IP options */
|
---|
| 762 | return ERR_VAL;
|
---|
| 763 | }
|
---|
| 764 | LWIP_ERROR("ip4_frag(): pbuf too short", p->len >= IP_HLEN, return ERR_VAL);
|
---|
| 765 |
|
---|
| 766 | /* Save original offset */
|
---|
| 767 | tmp = lwip_ntohs(IPH_OFFSET(iphdr));
|
---|
| 768 | ofo = tmp & IP_OFFMASK;
|
---|
| 769 | /* already fragmented? if so, the last fragment we create must have MF, too */
|
---|
| 770 | mf_set = tmp & IP_MF;
|
---|
| 771 |
|
---|
| 772 | left = (u16_t)(p->tot_len - IP_HLEN);
|
---|
| 773 |
|
---|
| 774 | while (left) {
|
---|
| 775 | /* Fill this fragment */
|
---|
| 776 | fragsize = LWIP_MIN(left, (u16_t)(nfb * 8));
|
---|
| 777 |
|
---|
| 778 | #if LWIP_NETIF_TX_SINGLE_PBUF
|
---|
| 779 | rambuf = pbuf_alloc(PBUF_IP, fragsize, PBUF_RAM);
|
---|
| 780 | if (rambuf == NULL) {
|
---|
| 781 | goto memerr;
|
---|
| 782 | }
|
---|
| 783 | LWIP_ASSERT("this needs a pbuf in one piece!",
|
---|
| 784 | (rambuf->len == rambuf->tot_len) && (rambuf->next == NULL));
|
---|
| 785 | poff += pbuf_copy_partial(p, rambuf->payload, fragsize, poff);
|
---|
| 786 | /* make room for the IP header */
|
---|
| 787 | if (pbuf_add_header(rambuf, IP_HLEN)) {
|
---|
| 788 | pbuf_free(rambuf);
|
---|
| 789 | goto memerr;
|
---|
| 790 | }
|
---|
| 791 | /* fill in the IP header */
|
---|
| 792 | SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
|
---|
| 793 | iphdr = (struct ip_hdr *)rambuf->payload;
|
---|
| 794 | #else /* LWIP_NETIF_TX_SINGLE_PBUF */
|
---|
| 795 | /* When not using a static buffer, create a chain of pbufs.
|
---|
| 796 | * The first will be a PBUF_RAM holding the link and IP header.
|
---|
| 797 | * The rest will be PBUF_REFs mirroring the pbuf chain to be fragged,
|
---|
| 798 | * but limited to the size of an mtu.
|
---|
| 799 | */
|
---|
| 800 | rambuf = pbuf_alloc(PBUF_LINK, IP_HLEN, PBUF_RAM);
|
---|
| 801 | if (rambuf == NULL) {
|
---|
| 802 | goto memerr;
|
---|
| 803 | }
|
---|
| 804 | LWIP_ASSERT("this needs a pbuf in one piece!",
|
---|
| 805 | (rambuf->len >= (IP_HLEN)));
|
---|
| 806 | SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
|
---|
| 807 | iphdr = (struct ip_hdr *)rambuf->payload;
|
---|
| 808 |
|
---|
| 809 | left_to_copy = fragsize;
|
---|
| 810 | while (left_to_copy) {
|
---|
| 811 | struct pbuf_custom_ref *pcr;
|
---|
| 812 | u16_t plen = (u16_t)(p->len - poff);
|
---|
| 813 | LWIP_ASSERT("p->len >= poff", p->len >= poff);
|
---|
| 814 | newpbuflen = LWIP_MIN(left_to_copy, plen);
|
---|
| 815 | /* Is this pbuf already empty? */
|
---|
| 816 | if (!newpbuflen) {
|
---|
| 817 | poff = 0;
|
---|
| 818 | p = p->next;
|
---|
| 819 | continue;
|
---|
| 820 | }
|
---|
| 821 | pcr = ip_frag_alloc_pbuf_custom_ref();
|
---|
| 822 | if (pcr == NULL) {
|
---|
| 823 | pbuf_free(rambuf);
|
---|
| 824 | goto memerr;
|
---|
| 825 | }
|
---|
| 826 | /* Mirror this pbuf, although we might not need all of it. */
|
---|
| 827 | newpbuf = pbuf_alloced_custom(PBUF_RAW, newpbuflen, PBUF_REF, &pcr->pc,
|
---|
| 828 | (u8_t *)p->payload + poff, newpbuflen);
|
---|
| 829 | if (newpbuf == NULL) {
|
---|
| 830 | ip_frag_free_pbuf_custom_ref(pcr);
|
---|
| 831 | pbuf_free(rambuf);
|
---|
| 832 | goto memerr;
|
---|
| 833 | }
|
---|
| 834 | pbuf_ref(p);
|
---|
| 835 | pcr->original = p;
|
---|
| 836 | pcr->pc.custom_free_function = ipfrag_free_pbuf_custom;
|
---|
| 837 |
|
---|
| 838 | /* Add it to end of rambuf's chain, but using pbuf_cat, not pbuf_chain
|
---|
| 839 | * so that it is removed when pbuf_dechain is later called on rambuf.
|
---|
| 840 | */
|
---|
| 841 | pbuf_cat(rambuf, newpbuf);
|
---|
| 842 | left_to_copy = (u16_t)(left_to_copy - newpbuflen);
|
---|
| 843 | if (left_to_copy) {
|
---|
| 844 | poff = 0;
|
---|
| 845 | p = p->next;
|
---|
| 846 | }
|
---|
| 847 | }
|
---|
| 848 | poff = (u16_t)(poff + newpbuflen);
|
---|
| 849 | #endif /* LWIP_NETIF_TX_SINGLE_PBUF */
|
---|
| 850 |
|
---|
| 851 | /* Correct header */
|
---|
| 852 | last = (left <= netif->mtu - IP_HLEN);
|
---|
| 853 |
|
---|
| 854 | /* Set new offset and MF flag */
|
---|
| 855 | tmp = (IP_OFFMASK & (ofo));
|
---|
| 856 | if (!last || mf_set) {
|
---|
| 857 | /* the last fragment has MF set if the input frame had it */
|
---|
| 858 | tmp = tmp | IP_MF;
|
---|
| 859 | }
|
---|
| 860 | IPH_OFFSET_SET(iphdr, lwip_htons(tmp));
|
---|
| 861 | IPH_LEN_SET(iphdr, lwip_htons((u16_t)(fragsize + IP_HLEN)));
|
---|
| 862 | IPH_CHKSUM_SET(iphdr, 0);
|
---|
| 863 | #if CHECKSUM_GEN_IP
|
---|
| 864 | IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) {
|
---|
| 865 | IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
|
---|
| 866 | }
|
---|
| 867 | #endif /* CHECKSUM_GEN_IP */
|
---|
| 868 |
|
---|
| 869 | /* No need for separate header pbuf - we allowed room for it in rambuf
|
---|
| 870 | * when allocated.
|
---|
| 871 | */
|
---|
| 872 | netif->output(netif, rambuf, dest);
|
---|
| 873 | IPFRAG_STATS_INC(ip_frag.xmit);
|
---|
| 874 |
|
---|
| 875 | /* Unfortunately we can't reuse rambuf - the hardware may still be
|
---|
| 876 | * using the buffer. Instead we free it (and the ensuing chain) and
|
---|
| 877 | * recreate it next time round the loop. If we're lucky the hardware
|
---|
| 878 | * will have already sent the packet, the free will really free, and
|
---|
| 879 | * there will be zero memory penalty.
|
---|
| 880 | */
|
---|
| 881 |
|
---|
| 882 | pbuf_free(rambuf);
|
---|
| 883 | left = (u16_t)(left - fragsize);
|
---|
| 884 | ofo = (u16_t)(ofo + nfb);
|
---|
| 885 | }
|
---|
| 886 | MIB2_STATS_INC(mib2.ipfragoks);
|
---|
| 887 | return ERR_OK;
|
---|
| 888 | memerr:
|
---|
| 889 | MIB2_STATS_INC(mib2.ipfragfails);
|
---|
| 890 | return ERR_MEM;
|
---|
| 891 | }
|
---|
| 892 | #endif /* IP_FRAG */
|
---|
| 893 |
|
---|
| 894 | #endif /* LWIP_IPV4 */
|
---|