1 | /**
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2 | * @file
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3 | *
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4 | * IPv6 fragmentation and reassembly.
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5 | */
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6 |
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7 | /*
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8 | * Copyright (c) 2010 Inico Technologies Ltd.
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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: Ivan Delamer <delamer@inicotech.com>
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36 | *
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37 | *
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38 | * Please coordinate changes and requests with Ivan Delamer
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39 | * <delamer@inicotech.com>
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40 | */
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41 |
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42 | #include "lwip/opt.h"
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43 | #include "lwip/ip6_frag.h"
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44 | #include "lwip/ip6.h"
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45 | #include "lwip/icmp6.h"
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46 | #include "lwip/nd6.h"
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47 | #include "lwip/ip.h"
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48 |
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49 | #include "lwip/pbuf.h"
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50 | #include "lwip/memp.h"
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51 | #include "lwip/stats.h"
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52 |
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53 | #include <string.h>
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54 |
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55 | #if LWIP_IPV6 && LWIP_IPV6_REASS /* don't build if not configured for use in lwipopts.h */
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56 |
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57 |
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58 | /** Setting this to 0, you can turn off checking the fragments for overlapping
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59 | * regions. The code gets a little smaller. Only use this if you know that
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60 | * overlapping won't occur on your network! */
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61 | #ifndef IP_REASS_CHECK_OVERLAP
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62 | #define IP_REASS_CHECK_OVERLAP 1
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63 | #endif /* IP_REASS_CHECK_OVERLAP */
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64 |
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65 | /** Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is
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66 | * full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller.
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67 | * Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA
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68 | * is set to 1, so one datagram can be reassembled at a time, only. */
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69 | #ifndef IP_REASS_FREE_OLDEST
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70 | #define IP_REASS_FREE_OLDEST 1
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71 | #endif /* IP_REASS_FREE_OLDEST */
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72 |
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73 | #if IPV6_FRAG_COPYHEADER
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74 | /* The number of bytes we need to "borrow" from (i.e., overwrite in) the header
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75 | * that precedes the fragment header for reassembly pruposes. */
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76 | #define IPV6_FRAG_REQROOM ((s16_t)(sizeof(struct ip6_reass_helper) - IP6_FRAG_HLEN))
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77 | #endif
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78 |
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79 | #define IP_REASS_FLAG_LASTFRAG 0x01
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80 |
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81 | /** This is a helper struct which holds the starting
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82 | * offset and the ending offset of this fragment to
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83 | * easily chain the fragments.
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84 | * It has the same packing requirements as the IPv6 header, since it replaces
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85 | * the Fragment Header in memory in incoming fragments to keep
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86 | * track of the various fragments.
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87 | */
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88 | #ifdef PACK_STRUCT_USE_INCLUDES
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89 | # include "arch/bpstruct.h"
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90 | #endif
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91 | PACK_STRUCT_BEGIN
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92 | struct ip6_reass_helper {
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93 | PACK_STRUCT_FIELD(struct pbuf *next_pbuf);
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94 | PACK_STRUCT_FIELD(u16_t start);
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95 | PACK_STRUCT_FIELD(u16_t end);
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96 | } PACK_STRUCT_STRUCT;
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97 | PACK_STRUCT_END
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98 | #ifdef PACK_STRUCT_USE_INCLUDES
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99 | # include "arch/epstruct.h"
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100 | #endif
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101 |
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102 | /* static variables */
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103 | static struct ip6_reassdata *reassdatagrams;
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104 | static u16_t ip6_reass_pbufcount;
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105 |
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106 | /* Forward declarations. */
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107 | static void ip6_reass_free_complete_datagram(struct ip6_reassdata *ipr);
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108 | #if IP_REASS_FREE_OLDEST
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109 | static void ip6_reass_remove_oldest_datagram(struct ip6_reassdata *ipr, int pbufs_needed);
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110 | #endif /* IP_REASS_FREE_OLDEST */
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111 |
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112 | void
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113 | ip6_reass_tmr(void)
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114 | {
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115 | struct ip6_reassdata *r, *tmp;
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116 |
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117 | #if !IPV6_FRAG_COPYHEADER
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118 | LWIP_ASSERT("sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN, set IPV6_FRAG_COPYHEADER to 1",
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119 | sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN);
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120 | #endif /* !IPV6_FRAG_COPYHEADER */
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121 |
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122 | r = reassdatagrams;
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123 | while (r != NULL) {
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124 | /* Decrement the timer. Once it reaches 0,
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125 | * clean up the incomplete fragment assembly */
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126 | if (r->timer > 0) {
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127 | r->timer--;
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128 | r = r->next;
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129 | } else {
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130 | /* reassembly timed out */
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131 | tmp = r;
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132 | /* get the next pointer before freeing */
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133 | r = r->next;
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134 | /* free the helper struct and all enqueued pbufs */
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135 | ip6_reass_free_complete_datagram(tmp);
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136 | }
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137 | }
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138 | }
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139 |
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140 | /**
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141 | * Free a datagram (struct ip6_reassdata) and all its pbufs.
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142 | * Updates the total count of enqueued pbufs (ip6_reass_pbufcount),
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143 | * sends an ICMP time exceeded packet.
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144 | *
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145 | * @param ipr datagram to free
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146 | */
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147 | static void
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148 | ip6_reass_free_complete_datagram(struct ip6_reassdata *ipr)
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149 | {
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150 | struct ip6_reassdata *prev;
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151 | u16_t pbufs_freed = 0;
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152 | u16_t clen;
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153 | struct pbuf *p;
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154 | struct ip6_reass_helper *iprh;
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155 |
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156 | #if LWIP_ICMP6
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157 | iprh = (struct ip6_reass_helper *)ipr->p->payload;
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158 | if (iprh->start == 0) {
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159 | /* The first fragment was received, send ICMP time exceeded. */
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160 | /* First, de-queue the first pbuf from r->p. */
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161 | p = ipr->p;
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162 | ipr->p = iprh->next_pbuf;
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163 | /* Restore the part that we've overwritten with our helper structure, or we
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164 | * might send garbage (and disclose a pointer) in the ICMPv6 reply. */
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165 | MEMCPY(p->payload, ipr->orig_hdr, sizeof(iprh));
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166 | /* Then, move back to the original ipv6 header (we are now pointing to Fragment header).
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167 | This cannot fail since we already checked when receiving this fragment. */
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168 | if (pbuf_header_force(p, (s16_t)((u8_t*)p->payload - (u8_t*)ipr->iphdr))) {
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169 | LWIP_ASSERT("ip6_reass_free: moving p->payload to ip6 header failed\n", 0);
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170 | }
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171 | else {
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172 | /* Reconstruct the zoned source and destination addresses, so that we do
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173 | * not end up sending the ICMP response over the wrong link. */
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174 | ip6_addr_t src_addr, dest_addr;
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175 | ip6_addr_copy_from_packed(src_addr, IPV6_FRAG_SRC(ipr));
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176 | ip6_addr_set_zone(&src_addr, ipr->src_zone);
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177 | ip6_addr_copy_from_packed(dest_addr, IPV6_FRAG_DEST(ipr));
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178 | ip6_addr_set_zone(&dest_addr, ipr->dest_zone);
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179 | /* Send the actual ICMP response. */
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180 | icmp6_time_exceeded_with_addrs(p, ICMP6_TE_FRAG, &src_addr, &dest_addr);
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181 | }
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182 | clen = pbuf_clen(p);
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183 | LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
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184 | pbufs_freed = (u16_t)(pbufs_freed + clen);
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185 | pbuf_free(p);
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186 | }
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187 | #endif /* LWIP_ICMP6 */
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188 |
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189 | /* First, free all received pbufs. The individual pbufs need to be released
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190 | separately as they have not yet been chained */
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191 | p = ipr->p;
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192 | while (p != NULL) {
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193 | struct pbuf *pcur;
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194 | iprh = (struct ip6_reass_helper *)p->payload;
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195 | pcur = p;
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196 | /* get the next pointer before freeing */
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197 | p = iprh->next_pbuf;
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198 | clen = pbuf_clen(pcur);
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199 | LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
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200 | pbufs_freed = (u16_t)(pbufs_freed + clen);
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201 | pbuf_free(pcur);
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202 | }
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203 |
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204 | /* Then, unchain the struct ip6_reassdata from the list and free it. */
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205 | if (ipr == reassdatagrams) {
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206 | reassdatagrams = ipr->next;
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207 | } else {
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208 | prev = reassdatagrams;
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209 | while (prev != NULL) {
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210 | if (prev->next == ipr) {
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211 | break;
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212 | }
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213 | prev = prev->next;
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214 | }
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215 | if (prev != NULL) {
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216 | prev->next = ipr->next;
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217 | }
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218 | }
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219 | memp_free(MEMP_IP6_REASSDATA, ipr);
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220 |
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221 | /* Finally, update number of pbufs in reassembly queue */
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222 | LWIP_ASSERT("ip_reass_pbufcount >= clen", ip6_reass_pbufcount >= pbufs_freed);
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223 | ip6_reass_pbufcount = (u16_t)(ip6_reass_pbufcount - pbufs_freed);
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224 | }
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225 |
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226 | #if IP_REASS_FREE_OLDEST
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227 | /**
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228 | * Free the oldest datagram to make room for enqueueing new fragments.
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229 | * The datagram ipr is not freed!
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230 | *
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231 | * @param ipr ip6_reassdata for the current fragment
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232 | * @param pbufs_needed number of pbufs needed to enqueue
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233 | * (used for freeing other datagrams if not enough space)
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234 | */
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235 | static void
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236 | ip6_reass_remove_oldest_datagram(struct ip6_reassdata *ipr, int pbufs_needed)
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237 | {
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238 | struct ip6_reassdata *r, *oldest;
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239 |
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240 | /* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs,
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241 | * but don't free the current datagram! */
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242 | do {
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243 | r = oldest = reassdatagrams;
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244 | while (r != NULL) {
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245 | if (r != ipr) {
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246 | if (r->timer <= oldest->timer) {
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247 | /* older than the previous oldest */
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248 | oldest = r;
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249 | }
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250 | }
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251 | r = r->next;
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252 | }
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253 | if (oldest == ipr) {
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254 | /* nothing to free, ipr is the only element on the list */
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255 | return;
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256 | }
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257 | if (oldest != NULL) {
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258 | ip6_reass_free_complete_datagram(oldest);
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259 | }
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260 | } while (((ip6_reass_pbufcount + pbufs_needed) > IP_REASS_MAX_PBUFS) && (reassdatagrams != NULL));
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261 | }
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262 | #endif /* IP_REASS_FREE_OLDEST */
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263 |
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264 | /**
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265 | * Reassembles incoming IPv6 fragments into an IPv6 datagram.
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266 | *
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267 | * @param p points to the IPv6 Fragment Header
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268 | * @return NULL if reassembly is incomplete, pbuf pointing to
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269 | * IPv6 Header if reassembly is complete
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270 | */
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271 | struct pbuf *
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272 | ip6_reass(struct pbuf *p)
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273 | {
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274 | struct ip6_reassdata *ipr, *ipr_prev;
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275 | struct ip6_reass_helper *iprh, *iprh_tmp, *iprh_prev=NULL;
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276 | struct ip6_frag_hdr *frag_hdr;
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277 | u16_t offset, len, start, end;
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278 | ptrdiff_t hdrdiff;
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279 | u16_t clen;
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280 | u8_t valid = 1;
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281 | struct pbuf *q, *next_pbuf;
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282 |
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283 | IP6_FRAG_STATS_INC(ip6_frag.recv);
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284 |
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285 | /* ip6_frag_hdr must be in the first pbuf, not chained. Checked by caller. */
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286 | LWIP_ASSERT("IPv6 fragment header does not fit in first pbuf",
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287 | p->len >= sizeof(struct ip6_frag_hdr));
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288 |
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289 | frag_hdr = (struct ip6_frag_hdr *) p->payload;
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290 |
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291 | clen = pbuf_clen(p);
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292 |
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293 | offset = lwip_ntohs(frag_hdr->_fragment_offset);
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294 |
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295 | /* Calculate fragment length from IPv6 payload length.
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296 | * Adjust for headers before Fragment Header.
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297 | * And finally adjust by Fragment Header length. */
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298 | len = lwip_ntohs(ip6_current_header()->_plen);
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299 | hdrdiff = (u8_t*)p->payload - (const u8_t*)ip6_current_header();
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300 | LWIP_ASSERT("not a valid pbuf (ip6_input check missing?)", hdrdiff <= 0xFFFF);
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301 | LWIP_ASSERT("not a valid pbuf (ip6_input check missing?)", hdrdiff >= IP6_HLEN);
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302 | hdrdiff -= IP6_HLEN;
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303 | hdrdiff += IP6_FRAG_HLEN;
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304 | if (hdrdiff > len) {
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305 | IP6_FRAG_STATS_INC(ip6_frag.proterr);
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306 | goto nullreturn;
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307 | }
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308 | len = (u16_t)(len - hdrdiff);
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309 | start = (offset & IP6_FRAG_OFFSET_MASK);
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310 | if (start > (0xFFFF - len)) {
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311 | /* u16_t overflow, cannot handle this */
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312 | IP6_FRAG_STATS_INC(ip6_frag.proterr);
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313 | goto nullreturn;
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314 | }
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315 |
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316 | /* Look for the datagram the fragment belongs to in the current datagram queue,
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317 | * remembering the previous in the queue for later dequeueing. */
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318 | for (ipr = reassdatagrams, ipr_prev = NULL; ipr != NULL; ipr = ipr->next) {
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319 | /* Check if the incoming fragment matches the one currently present
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320 | in the reassembly buffer. If so, we proceed with copying the
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321 | fragment into the buffer. */
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322 | if ((frag_hdr->_identification == ipr->identification) &&
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323 | ip6_addr_cmp_packed(ip6_current_src_addr(), &(IPV6_FRAG_SRC(ipr)), ipr->src_zone) &&
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324 | ip6_addr_cmp_packed(ip6_current_dest_addr(), &(IPV6_FRAG_DEST(ipr)), ipr->dest_zone)) {
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325 | IP6_FRAG_STATS_INC(ip6_frag.cachehit);
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326 | break;
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327 | }
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328 | ipr_prev = ipr;
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329 | }
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330 |
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331 | if (ipr == NULL) {
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332 | /* Enqueue a new datagram into the datagram queue */
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333 | ipr = (struct ip6_reassdata *)memp_malloc(MEMP_IP6_REASSDATA);
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334 | if (ipr == NULL) {
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335 | #if IP_REASS_FREE_OLDEST
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336 | /* Make room and try again. */
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337 | ip6_reass_remove_oldest_datagram(ipr, clen);
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338 | ipr = (struct ip6_reassdata *)memp_malloc(MEMP_IP6_REASSDATA);
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339 | if (ipr != NULL) {
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340 | /* re-search ipr_prev since it might have been removed */
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341 | for (ipr_prev = reassdatagrams; ipr_prev != NULL; ipr_prev = ipr_prev->next) {
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342 | if (ipr_prev->next == ipr) {
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343 | break;
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344 | }
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345 | }
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346 | } else
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347 | #endif /* IP_REASS_FREE_OLDEST */
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348 | {
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349 | IP6_FRAG_STATS_INC(ip6_frag.memerr);
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350 | goto nullreturn;
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351 | }
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352 | }
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353 |
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354 | memset(ipr, 0, sizeof(struct ip6_reassdata));
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355 | ipr->timer = IPV6_REASS_MAXAGE;
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356 |
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357 | /* enqueue the new structure to the front of the list */
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358 | ipr->next = reassdatagrams;
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359 | reassdatagrams = ipr;
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360 |
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361 | /* Use the current IPv6 header for src/dest address reference.
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362 | * Eventually, we will replace it when we get the first fragment
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363 | * (it might be this one, in any case, it is done later). */
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364 | /* need to use the none-const pointer here: */
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365 | ipr->iphdr = ip_data.current_ip6_header;
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366 | #if IPV6_FRAG_COPYHEADER
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367 | MEMCPY(&ipr->src, &ip6_current_header()->src, sizeof(ipr->src));
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368 | MEMCPY(&ipr->dest, &ip6_current_header()->dest, sizeof(ipr->dest));
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369 | #endif /* IPV6_FRAG_COPYHEADER */
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370 | #if LWIP_IPV6_SCOPES
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371 | /* Also store the address zone information.
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372 | * @todo It is possible that due to netif destruction and recreation, the
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373 | * stored zones end up resolving to a different interface. In that case, we
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374 | * risk sending a "time exceeded" ICMP response over the wrong link.
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375 | * Ideally, netif destruction would clean up matching pending reassembly
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376 | * structures, but custom zone mappings would make that non-trivial. */
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377 | ipr->src_zone = ip6_addr_zone(ip6_current_src_addr());
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378 | ipr->dest_zone = ip6_addr_zone(ip6_current_dest_addr());
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379 | #endif /* LWIP_IPV6_SCOPES */
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380 | /* copy the fragmented packet id. */
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381 | ipr->identification = frag_hdr->_identification;
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382 |
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383 | /* copy the nexth field */
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384 | ipr->nexth = frag_hdr->_nexth;
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385 | }
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386 |
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387 | /* Check if we are allowed to enqueue more datagrams. */
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388 | if ((ip6_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS) {
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389 | #if IP_REASS_FREE_OLDEST
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390 | ip6_reass_remove_oldest_datagram(ipr, clen);
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391 | if ((ip6_reass_pbufcount + clen) <= IP_REASS_MAX_PBUFS) {
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392 | /* re-search ipr_prev since it might have been removed */
|
---|
393 | for (ipr_prev = reassdatagrams; ipr_prev != NULL; ipr_prev = ipr_prev->next) {
|
---|
394 | if (ipr_prev->next == ipr) {
|
---|
395 | break;
|
---|
396 | }
|
---|
397 | }
|
---|
398 | } else
|
---|
399 | #endif /* IP_REASS_FREE_OLDEST */
|
---|
400 | {
|
---|
401 | /* @todo: send ICMPv6 time exceeded here? */
|
---|
402 | /* drop this pbuf */
|
---|
403 | IP6_FRAG_STATS_INC(ip6_frag.memerr);
|
---|
404 | goto nullreturn;
|
---|
405 | }
|
---|
406 | }
|
---|
407 |
|
---|
408 | /* Overwrite Fragment Header with our own helper struct. */
|
---|
409 | #if IPV6_FRAG_COPYHEADER
|
---|
410 | if (IPV6_FRAG_REQROOM > 0) {
|
---|
411 | /* Make room for struct ip6_reass_helper (only required if sizeof(void*) > 4).
|
---|
412 | This cannot fail since we already checked when receiving this fragment. */
|
---|
413 | u8_t hdrerr = pbuf_header_force(p, IPV6_FRAG_REQROOM);
|
---|
414 | LWIP_UNUSED_ARG(hdrerr); /* in case of LWIP_NOASSERT */
|
---|
415 | LWIP_ASSERT("no room for struct ip6_reass_helper", hdrerr == 0);
|
---|
416 | }
|
---|
417 | #else /* IPV6_FRAG_COPYHEADER */
|
---|
418 | LWIP_ASSERT("sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN, set IPV6_FRAG_COPYHEADER to 1",
|
---|
419 | sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN);
|
---|
420 | #endif /* IPV6_FRAG_COPYHEADER */
|
---|
421 |
|
---|
422 | /* Prepare the pointer to the helper structure, and its initial values.
|
---|
423 | * Do not yet write to the structure itself, as we still have to make a
|
---|
424 | * backup of the original data, and we should not do that until we know for
|
---|
425 | * sure that we are going to add this packet to the list. */
|
---|
426 | iprh = (struct ip6_reass_helper *)p->payload;
|
---|
427 | next_pbuf = NULL;
|
---|
428 | end = (u16_t)(start + len);
|
---|
429 |
|
---|
430 | /* find the right place to insert this pbuf */
|
---|
431 | /* Iterate through until we either get to the end of the list (append),
|
---|
432 | * or we find on with a larger offset (insert). */
|
---|
433 | for (q = ipr->p; q != NULL;) {
|
---|
434 | iprh_tmp = (struct ip6_reass_helper*)q->payload;
|
---|
435 | if (start < iprh_tmp->start) {
|
---|
436 | #if IP_REASS_CHECK_OVERLAP
|
---|
437 | if (end > iprh_tmp->start) {
|
---|
438 | /* fragment overlaps with following, throw away */
|
---|
439 | IP6_FRAG_STATS_INC(ip6_frag.proterr);
|
---|
440 | goto nullreturn;
|
---|
441 | }
|
---|
442 | if (iprh_prev != NULL) {
|
---|
443 | if (start < iprh_prev->end) {
|
---|
444 | /* fragment overlaps with previous, throw away */
|
---|
445 | IP6_FRAG_STATS_INC(ip6_frag.proterr);
|
---|
446 | goto nullreturn;
|
---|
447 | }
|
---|
448 | }
|
---|
449 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
450 | /* the new pbuf should be inserted before this */
|
---|
451 | next_pbuf = q;
|
---|
452 | if (iprh_prev != NULL) {
|
---|
453 | /* not the fragment with the lowest offset */
|
---|
454 | iprh_prev->next_pbuf = p;
|
---|
455 | } else {
|
---|
456 | /* fragment with the lowest offset */
|
---|
457 | ipr->p = p;
|
---|
458 | }
|
---|
459 | break;
|
---|
460 | } else if (start == iprh_tmp->start) {
|
---|
461 | /* received the same datagram twice: no need to keep the datagram */
|
---|
462 | goto nullreturn;
|
---|
463 | #if IP_REASS_CHECK_OVERLAP
|
---|
464 | } else if (start < iprh_tmp->end) {
|
---|
465 | /* overlap: no need to keep the new datagram */
|
---|
466 | IP6_FRAG_STATS_INC(ip6_frag.proterr);
|
---|
467 | goto nullreturn;
|
---|
468 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
469 | } else {
|
---|
470 | /* Check if the fragments received so far have no gaps. */
|
---|
471 | if (iprh_prev != NULL) {
|
---|
472 | if (iprh_prev->end != iprh_tmp->start) {
|
---|
473 | /* There is a fragment missing between the current
|
---|
474 | * and the previous fragment */
|
---|
475 | valid = 0;
|
---|
476 | }
|
---|
477 | }
|
---|
478 | }
|
---|
479 | q = iprh_tmp->next_pbuf;
|
---|
480 | iprh_prev = iprh_tmp;
|
---|
481 | }
|
---|
482 |
|
---|
483 | /* If q is NULL, then we made it to the end of the list. Determine what to do now */
|
---|
484 | if (q == NULL) {
|
---|
485 | if (iprh_prev != NULL) {
|
---|
486 | /* this is (for now), the fragment with the highest offset:
|
---|
487 | * chain it to the last fragment */
|
---|
488 | #if IP_REASS_CHECK_OVERLAP
|
---|
489 | LWIP_ASSERT("check fragments don't overlap", iprh_prev->end <= start);
|
---|
490 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
491 | iprh_prev->next_pbuf = p;
|
---|
492 | if (iprh_prev->end != start) {
|
---|
493 | valid = 0;
|
---|
494 | }
|
---|
495 | } else {
|
---|
496 | #if IP_REASS_CHECK_OVERLAP
|
---|
497 | LWIP_ASSERT("no previous fragment, this must be the first fragment!",
|
---|
498 | ipr->p == NULL);
|
---|
499 | #endif /* IP_REASS_CHECK_OVERLAP */
|
---|
500 | /* this is the first fragment we ever received for this ip datagram */
|
---|
501 | ipr->p = p;
|
---|
502 | }
|
---|
503 | }
|
---|
504 |
|
---|
505 | /* Track the current number of pbufs current 'in-flight', in order to limit
|
---|
506 | the number of fragments that may be enqueued at any one time */
|
---|
507 | ip6_reass_pbufcount = (u16_t)(ip6_reass_pbufcount + clen);
|
---|
508 |
|
---|
509 | /* Remember IPv6 header if this is the first fragment. */
|
---|
510 | if (start == 0) {
|
---|
511 | /* need to use the none-const pointer here: */
|
---|
512 | ipr->iphdr = ip_data.current_ip6_header;
|
---|
513 | /* Make a backup of the part of the packet data that we are about to
|
---|
514 | * overwrite, so that we can restore the original later. */
|
---|
515 | MEMCPY(ipr->orig_hdr, p->payload, sizeof(*iprh));
|
---|
516 | /* For IPV6_FRAG_COPYHEADER there is no need to copy src/dst again, as they
|
---|
517 | * will be the same as they were. With LWIP_IPV6_SCOPES, the same applies
|
---|
518 | * to the source/destination zones. */
|
---|
519 | }
|
---|
520 | /* Only after the backup do we get to fill in the actual helper structure. */
|
---|
521 | iprh->next_pbuf = next_pbuf;
|
---|
522 | iprh->start = start;
|
---|
523 | iprh->end = end;
|
---|
524 |
|
---|
525 | /* If this is the last fragment, calculate total packet length. */
|
---|
526 | if ((offset & IP6_FRAG_MORE_FLAG) == 0) {
|
---|
527 | ipr->datagram_len = iprh->end;
|
---|
528 | }
|
---|
529 |
|
---|
530 | /* Additional validity tests: we have received first and last fragment. */
|
---|
531 | iprh_tmp = (struct ip6_reass_helper*)ipr->p->payload;
|
---|
532 | if (iprh_tmp->start != 0) {
|
---|
533 | valid = 0;
|
---|
534 | }
|
---|
535 | if (ipr->datagram_len == 0) {
|
---|
536 | valid = 0;
|
---|
537 | }
|
---|
538 |
|
---|
539 | /* Final validity test: no gaps between current and last fragment. */
|
---|
540 | iprh_prev = iprh;
|
---|
541 | q = iprh->next_pbuf;
|
---|
542 | while ((q != NULL) && valid) {
|
---|
543 | iprh = (struct ip6_reass_helper*)q->payload;
|
---|
544 | if (iprh_prev->end != iprh->start) {
|
---|
545 | valid = 0;
|
---|
546 | break;
|
---|
547 | }
|
---|
548 | iprh_prev = iprh;
|
---|
549 | q = iprh->next_pbuf;
|
---|
550 | }
|
---|
551 |
|
---|
552 | if (valid) {
|
---|
553 | /* All fragments have been received */
|
---|
554 | struct ip6_hdr* iphdr_ptr;
|
---|
555 |
|
---|
556 | /* chain together the pbufs contained within the ip6_reassdata list. */
|
---|
557 | iprh = (struct ip6_reass_helper*) ipr->p->payload;
|
---|
558 | while (iprh != NULL) {
|
---|
559 | next_pbuf = iprh->next_pbuf;
|
---|
560 | if (next_pbuf != NULL) {
|
---|
561 | /* Save next helper struct (will be hidden in next step). */
|
---|
562 | iprh_tmp = (struct ip6_reass_helper*)next_pbuf->payload;
|
---|
563 |
|
---|
564 | /* hide the fragment header for every succeeding fragment */
|
---|
565 | pbuf_remove_header(next_pbuf, IP6_FRAG_HLEN);
|
---|
566 | #if IPV6_FRAG_COPYHEADER
|
---|
567 | if (IPV6_FRAG_REQROOM > 0) {
|
---|
568 | /* hide the extra bytes borrowed from ip6_hdr for struct ip6_reass_helper */
|
---|
569 | u8_t hdrerr = pbuf_remove_header(next_pbuf, IPV6_FRAG_REQROOM);
|
---|
570 | LWIP_UNUSED_ARG(hdrerr); /* in case of LWIP_NOASSERT */
|
---|
571 | LWIP_ASSERT("no room for struct ip6_reass_helper", hdrerr == 0);
|
---|
572 | }
|
---|
573 | #endif
|
---|
574 | pbuf_cat(ipr->p, next_pbuf);
|
---|
575 | }
|
---|
576 | else {
|
---|
577 | iprh_tmp = NULL;
|
---|
578 | }
|
---|
579 |
|
---|
580 | iprh = iprh_tmp;
|
---|
581 | }
|
---|
582 |
|
---|
583 | /* Get the first pbuf. */
|
---|
584 | p = ipr->p;
|
---|
585 |
|
---|
586 | #if IPV6_FRAG_COPYHEADER
|
---|
587 | if (IPV6_FRAG_REQROOM > 0) {
|
---|
588 | u8_t hdrerr;
|
---|
589 | /* Restore (only) the bytes that we overwrote beyond the fragment header.
|
---|
590 | * Those bytes may belong to either the IPv6 header or an extension
|
---|
591 | * header placed before the fragment header. */
|
---|
592 | MEMCPY(p->payload, ipr->orig_hdr, IPV6_FRAG_REQROOM);
|
---|
593 | /* get back room for struct ip6_reass_helper (only required if sizeof(void*) > 4) */
|
---|
594 | hdrerr = pbuf_remove_header(p, IPV6_FRAG_REQROOM);
|
---|
595 | LWIP_UNUSED_ARG(hdrerr); /* in case of LWIP_NOASSERT */
|
---|
596 | LWIP_ASSERT("no room for struct ip6_reass_helper", hdrerr == 0);
|
---|
597 | }
|
---|
598 | #endif
|
---|
599 |
|
---|
600 | /* We need to get rid of the fragment header itself, which is somewhere in
|
---|
601 | * the middle of the packet (but still in the first pbuf of the chain).
|
---|
602 | * Getting rid of the header is required by RFC 2460 Sec. 4.5 and necessary
|
---|
603 | * in order to be able to reassemble packets that are close to full size
|
---|
604 | * (i.e., around 65535 bytes). We simply move up all the headers before the
|
---|
605 | * fragment header, including the IPv6 header, and adjust the payload start
|
---|
606 | * accordingly. This works because all these headers are in the first pbuf
|
---|
607 | * of the chain, and because the caller adjusts all its pointers on
|
---|
608 | * successful reassembly. */
|
---|
609 | MEMMOVE((u8_t*)ipr->iphdr + sizeof(struct ip6_frag_hdr), ipr->iphdr,
|
---|
610 | (size_t)((u8_t*)p->payload - (u8_t*)ipr->iphdr));
|
---|
611 |
|
---|
612 | /* This is where the IPv6 header is now. */
|
---|
613 | iphdr_ptr = (struct ip6_hdr*)((u8_t*)ipr->iphdr +
|
---|
614 | sizeof(struct ip6_frag_hdr));
|
---|
615 |
|
---|
616 | /* Adjust datagram length by adding header lengths. */
|
---|
617 | ipr->datagram_len = (u16_t)(ipr->datagram_len + ((u8_t*)p->payload - (u8_t*)iphdr_ptr)
|
---|
618 | - IP6_HLEN);
|
---|
619 |
|
---|
620 | /* Set payload length in ip header. */
|
---|
621 | iphdr_ptr->_plen = lwip_htons(ipr->datagram_len);
|
---|
622 |
|
---|
623 | /* With the fragment header gone, we now need to adjust the next-header
|
---|
624 | * field of whatever header was originally before it. Since the packet made
|
---|
625 | * it through the original header processing routines at least up to the
|
---|
626 | * fragment header, we do not need any further sanity checks here. */
|
---|
627 | if (IP6H_NEXTH(iphdr_ptr) == IP6_NEXTH_FRAGMENT) {
|
---|
628 | iphdr_ptr->_nexth = ipr->nexth;
|
---|
629 | } else {
|
---|
630 | u8_t *ptr = (u8_t *)iphdr_ptr + IP6_HLEN;
|
---|
631 | while (*ptr != IP6_NEXTH_FRAGMENT) {
|
---|
632 | ptr += 8 * (1 + ptr[1]);
|
---|
633 | }
|
---|
634 | *ptr = ipr->nexth;
|
---|
635 | }
|
---|
636 |
|
---|
637 | /* release the resources allocated for the fragment queue entry */
|
---|
638 | if (reassdatagrams == ipr) {
|
---|
639 | /* it was the first in the list */
|
---|
640 | reassdatagrams = ipr->next;
|
---|
641 | } else {
|
---|
642 | /* it wasn't the first, so it must have a valid 'prev' */
|
---|
643 | LWIP_ASSERT("sanity check linked list", ipr_prev != NULL);
|
---|
644 | ipr_prev->next = ipr->next;
|
---|
645 | }
|
---|
646 | memp_free(MEMP_IP6_REASSDATA, ipr);
|
---|
647 |
|
---|
648 | /* adjust the number of pbufs currently queued for reassembly. */
|
---|
649 | clen = pbuf_clen(p);
|
---|
650 | LWIP_ASSERT("ip6_reass_pbufcount >= clen", ip6_reass_pbufcount >= clen);
|
---|
651 | ip6_reass_pbufcount = (u16_t)(ip6_reass_pbufcount - clen);
|
---|
652 |
|
---|
653 | /* Move pbuf back to IPv6 header. This should never fail. */
|
---|
654 | if (pbuf_header_force(p, (s16_t)((u8_t*)p->payload - (u8_t*)iphdr_ptr))) {
|
---|
655 | LWIP_ASSERT("ip6_reass: moving p->payload to ip6 header failed\n", 0);
|
---|
656 | pbuf_free(p);
|
---|
657 | return NULL;
|
---|
658 | }
|
---|
659 |
|
---|
660 | /* Return the pbuf chain */
|
---|
661 | return p;
|
---|
662 | }
|
---|
663 | /* the datagram is not (yet?) reassembled completely */
|
---|
664 | return NULL;
|
---|
665 |
|
---|
666 | nullreturn:
|
---|
667 | IP6_FRAG_STATS_INC(ip6_frag.drop);
|
---|
668 | pbuf_free(p);
|
---|
669 | return NULL;
|
---|
670 | }
|
---|
671 |
|
---|
672 | #endif /* LWIP_IPV6 && LWIP_IPV6_REASS */
|
---|
673 |
|
---|
674 | #if LWIP_IPV6 && LWIP_IPV6_FRAG
|
---|
675 |
|
---|
676 | #if !LWIP_NETIF_TX_SINGLE_PBUF
|
---|
677 | /** Allocate a new struct pbuf_custom_ref */
|
---|
678 | static struct pbuf_custom_ref*
|
---|
679 | ip6_frag_alloc_pbuf_custom_ref(void)
|
---|
680 | {
|
---|
681 | return (struct pbuf_custom_ref*)memp_malloc(MEMP_FRAG_PBUF);
|
---|
682 | }
|
---|
683 |
|
---|
684 | /** Free a struct pbuf_custom_ref */
|
---|
685 | static void
|
---|
686 | ip6_frag_free_pbuf_custom_ref(struct pbuf_custom_ref* p)
|
---|
687 | {
|
---|
688 | LWIP_ASSERT("p != NULL", p != NULL);
|
---|
689 | memp_free(MEMP_FRAG_PBUF, p);
|
---|
690 | }
|
---|
691 |
|
---|
692 | /** Free-callback function to free a 'struct pbuf_custom_ref', called by
|
---|
693 | * pbuf_free. */
|
---|
694 | static void
|
---|
695 | ip6_frag_free_pbuf_custom(struct pbuf *p)
|
---|
696 | {
|
---|
697 | struct pbuf_custom_ref *pcr = (struct pbuf_custom_ref*)p;
|
---|
698 | LWIP_ASSERT("pcr != NULL", pcr != NULL);
|
---|
699 | LWIP_ASSERT("pcr == p", (void*)pcr == (void*)p);
|
---|
700 | if (pcr->original != NULL) {
|
---|
701 | pbuf_free(pcr->original);
|
---|
702 | }
|
---|
703 | ip6_frag_free_pbuf_custom_ref(pcr);
|
---|
704 | }
|
---|
705 | #endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
|
---|
706 |
|
---|
707 | /**
|
---|
708 | * Fragment an IPv6 datagram if too large for the netif or path MTU.
|
---|
709 | *
|
---|
710 | * Chop the datagram in MTU sized chunks and send them in order
|
---|
711 | * by pointing PBUF_REFs into p
|
---|
712 | *
|
---|
713 | * @param p ipv6 packet to send
|
---|
714 | * @param netif the netif on which to send
|
---|
715 | * @param dest destination ipv6 address to which to send
|
---|
716 | *
|
---|
717 | * @return ERR_OK if sent successfully, err_t otherwise
|
---|
718 | */
|
---|
719 | err_t
|
---|
720 | ip6_frag(struct pbuf *p, struct netif *netif, const ip6_addr_t *dest)
|
---|
721 | {
|
---|
722 | struct ip6_hdr *original_ip6hdr;
|
---|
723 | struct ip6_hdr *ip6hdr;
|
---|
724 | struct ip6_frag_hdr *frag_hdr;
|
---|
725 | struct pbuf *rambuf;
|
---|
726 | #if !LWIP_NETIF_TX_SINGLE_PBUF
|
---|
727 | struct pbuf *newpbuf;
|
---|
728 | u16_t newpbuflen = 0;
|
---|
729 | u16_t left_to_copy;
|
---|
730 | #endif
|
---|
731 | static u32_t identification;
|
---|
732 | u16_t left, cop;
|
---|
733 | const u16_t mtu = nd6_get_destination_mtu(dest, netif);
|
---|
734 | const u16_t nfb = (u16_t)((mtu - (IP6_HLEN + IP6_FRAG_HLEN)) & IP6_FRAG_OFFSET_MASK);
|
---|
735 | u16_t fragment_offset = 0;
|
---|
736 | u16_t last;
|
---|
737 | u16_t poff = IP6_HLEN;
|
---|
738 |
|
---|
739 | identification++;
|
---|
740 |
|
---|
741 | original_ip6hdr = (struct ip6_hdr *)p->payload;
|
---|
742 |
|
---|
743 | /* @todo we assume there are no options in the unfragmentable part (IPv6 header). */
|
---|
744 | LWIP_ASSERT("p->tot_len >= IP6_HLEN", p->tot_len >= IP6_HLEN);
|
---|
745 | left = (u16_t)(p->tot_len - IP6_HLEN);
|
---|
746 |
|
---|
747 | while (left) {
|
---|
748 | last = (left <= nfb);
|
---|
749 |
|
---|
750 | /* Fill this fragment */
|
---|
751 | cop = last ? left : nfb;
|
---|
752 |
|
---|
753 | #if LWIP_NETIF_TX_SINGLE_PBUF
|
---|
754 | rambuf = pbuf_alloc(PBUF_IP, cop + IP6_FRAG_HLEN, PBUF_RAM);
|
---|
755 | if (rambuf == NULL) {
|
---|
756 | IP6_FRAG_STATS_INC(ip6_frag.memerr);
|
---|
757 | return ERR_MEM;
|
---|
758 | }
|
---|
759 | LWIP_ASSERT("this needs a pbuf in one piece!",
|
---|
760 | (rambuf->len == rambuf->tot_len) && (rambuf->next == NULL));
|
---|
761 | poff += pbuf_copy_partial(p, (u8_t*)rambuf->payload + IP6_FRAG_HLEN, cop, poff);
|
---|
762 | /* make room for the IP header */
|
---|
763 | if (pbuf_add_header(rambuf, IP6_HLEN)) {
|
---|
764 | pbuf_free(rambuf);
|
---|
765 | IP6_FRAG_STATS_INC(ip6_frag.memerr);
|
---|
766 | return ERR_MEM;
|
---|
767 | }
|
---|
768 | /* fill in the IP header */
|
---|
769 | SMEMCPY(rambuf->payload, original_ip6hdr, IP6_HLEN);
|
---|
770 | ip6hdr = (struct ip6_hdr *)rambuf->payload;
|
---|
771 | frag_hdr = (struct ip6_frag_hdr *)((u8_t*)rambuf->payload + IP6_HLEN);
|
---|
772 | #else
|
---|
773 | /* When not using a static buffer, create a chain of pbufs.
|
---|
774 | * The first will be a PBUF_RAM holding the link, IPv6, and Fragment header.
|
---|
775 | * The rest will be PBUF_REFs mirroring the pbuf chain to be fragged,
|
---|
776 | * but limited to the size of an mtu.
|
---|
777 | */
|
---|
778 | rambuf = pbuf_alloc(PBUF_LINK, IP6_HLEN + IP6_FRAG_HLEN, PBUF_RAM);
|
---|
779 | if (rambuf == NULL) {
|
---|
780 | IP6_FRAG_STATS_INC(ip6_frag.memerr);
|
---|
781 | return ERR_MEM;
|
---|
782 | }
|
---|
783 | LWIP_ASSERT("this needs a pbuf in one piece!",
|
---|
784 | (p->len >= (IP6_HLEN)));
|
---|
785 | SMEMCPY(rambuf->payload, original_ip6hdr, IP6_HLEN);
|
---|
786 | ip6hdr = (struct ip6_hdr *)rambuf->payload;
|
---|
787 | frag_hdr = (struct ip6_frag_hdr *)((u8_t*)rambuf->payload + IP6_HLEN);
|
---|
788 |
|
---|
789 | /* Can just adjust p directly for needed offset. */
|
---|
790 | p->payload = (u8_t *)p->payload + poff;
|
---|
791 | p->len = (u16_t)(p->len - poff);
|
---|
792 | p->tot_len = (u16_t)(p->tot_len - poff);
|
---|
793 |
|
---|
794 | left_to_copy = cop;
|
---|
795 | while (left_to_copy) {
|
---|
796 | struct pbuf_custom_ref *pcr;
|
---|
797 | newpbuflen = (left_to_copy < p->len) ? left_to_copy : p->len;
|
---|
798 | /* Is this pbuf already empty? */
|
---|
799 | if (!newpbuflen) {
|
---|
800 | p = p->next;
|
---|
801 | continue;
|
---|
802 | }
|
---|
803 | pcr = ip6_frag_alloc_pbuf_custom_ref();
|
---|
804 | if (pcr == NULL) {
|
---|
805 | pbuf_free(rambuf);
|
---|
806 | IP6_FRAG_STATS_INC(ip6_frag.memerr);
|
---|
807 | return ERR_MEM;
|
---|
808 | }
|
---|
809 | /* Mirror this pbuf, although we might not need all of it. */
|
---|
810 | newpbuf = pbuf_alloced_custom(PBUF_RAW, newpbuflen, PBUF_REF, &pcr->pc, p->payload, newpbuflen);
|
---|
811 | if (newpbuf == NULL) {
|
---|
812 | ip6_frag_free_pbuf_custom_ref(pcr);
|
---|
813 | pbuf_free(rambuf);
|
---|
814 | IP6_FRAG_STATS_INC(ip6_frag.memerr);
|
---|
815 | return ERR_MEM;
|
---|
816 | }
|
---|
817 | pbuf_ref(p);
|
---|
818 | pcr->original = p;
|
---|
819 | pcr->pc.custom_free_function = ip6_frag_free_pbuf_custom;
|
---|
820 |
|
---|
821 | /* Add it to end of rambuf's chain, but using pbuf_cat, not pbuf_chain
|
---|
822 | * so that it is removed when pbuf_dechain is later called on rambuf.
|
---|
823 | */
|
---|
824 | pbuf_cat(rambuf, newpbuf);
|
---|
825 | left_to_copy = (u16_t)(left_to_copy - newpbuflen);
|
---|
826 | if (left_to_copy) {
|
---|
827 | p = p->next;
|
---|
828 | }
|
---|
829 | }
|
---|
830 | poff = newpbuflen;
|
---|
831 | #endif /* LWIP_NETIF_TX_SINGLE_PBUF */
|
---|
832 |
|
---|
833 | /* Set headers */
|
---|
834 | frag_hdr->_nexth = original_ip6hdr->_nexth;
|
---|
835 | frag_hdr->reserved = 0;
|
---|
836 | frag_hdr->_fragment_offset = lwip_htons((u16_t)((fragment_offset & IP6_FRAG_OFFSET_MASK) | (last ? 0 : IP6_FRAG_MORE_FLAG)));
|
---|
837 | frag_hdr->_identification = lwip_htonl(identification);
|
---|
838 |
|
---|
839 | IP6H_NEXTH_SET(ip6hdr, IP6_NEXTH_FRAGMENT);
|
---|
840 | IP6H_PLEN_SET(ip6hdr, (u16_t)(cop + IP6_FRAG_HLEN));
|
---|
841 |
|
---|
842 | /* No need for separate header pbuf - we allowed room for it in rambuf
|
---|
843 | * when allocated.
|
---|
844 | */
|
---|
845 | IP6_FRAG_STATS_INC(ip6_frag.xmit);
|
---|
846 | netif->output_ip6(netif, rambuf, dest);
|
---|
847 |
|
---|
848 | /* Unfortunately we can't reuse rambuf - the hardware may still be
|
---|
849 | * using the buffer. Instead we free it (and the ensuing chain) and
|
---|
850 | * recreate it next time round the loop. If we're lucky the hardware
|
---|
851 | * will have already sent the packet, the free will really free, and
|
---|
852 | * there will be zero memory penalty.
|
---|
853 | */
|
---|
854 |
|
---|
855 | pbuf_free(rambuf);
|
---|
856 | left = (u16_t)(left - cop);
|
---|
857 | fragment_offset = (u16_t)(fragment_offset + cop);
|
---|
858 | }
|
---|
859 | return ERR_OK;
|
---|
860 | }
|
---|
861 |
|
---|
862 | #endif /* LWIP_IPV6 && LWIP_IPV6_FRAG */
|
---|