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) {
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386 | /* not the fragment with the lowest offset */
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387 | #if IP_REASS_CHECK_OVERLAP
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388 | if ((iprh->start < iprh_prev->end) || (iprh->end > iprh_tmp->start)) {
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389 | /* fragment overlaps with previous or following, throw away */
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390 | return IP_REASS_VALIDATE_PBUF_DROPPED;
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391 | }
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392 | #endif /* IP_REASS_CHECK_OVERLAP */
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393 | iprh_prev->next_pbuf = new_p;
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394 | if (iprh_prev->end != iprh->start) {
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395 | /* There is a fragment missing between the current
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396 | * and the previous fragment */
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397 | valid = 0;
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398 | }
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399 | } else {
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400 | #if IP_REASS_CHECK_OVERLAP
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401 | if (iprh->end > iprh_tmp->start) {
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402 | /* fragment overlaps with following, throw away */
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403 | return IP_REASS_VALIDATE_PBUF_DROPPED;
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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 */
|
---|