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Rev | Author | Line No. | Line |
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1 | office | 1 | /** |
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 | |||
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 | |||
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 | |||
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 | |||
53 | #include <string.h> |
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54 | |||
55 | #if LWIP_IPV6 && LWIP_IPV6_REASS /* don't build if not configured for use in lwipopts.h */ |
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56 | |||
57 | |||
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 | |||
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 | |||
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 | |||
79 | #define IP_REASS_FLAG_LASTFRAG 0x01 |
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80 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
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 | |||
283 | IP6_FRAG_STATS_INC(ip6_frag.recv); |
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284 | |||
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 | |||
289 | frag_hdr = (struct ip6_frag_hdr *) p->payload; |
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290 | |||
291 | clen = pbuf_clen(p); |
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292 | |||
293 | offset = lwip_ntohs(frag_hdr->_fragment_offset); |
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294 | |||
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 | |||
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 | |||
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 | |||
354 | memset(ipr, 0, sizeof(struct ip6_reassdata)); |
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355 | ipr->timer = IPV6_REASS_MAXAGE; |
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356 | |||
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 | |||
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 | |||
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 | |||
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 */ |
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393 | for (ipr_prev = reassdatagrams; ipr_prev != NULL; ipr_prev = ipr_prev->next) { |
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394 | if (ipr_prev->next == ipr) { |
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395 | break; |
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396 | } |
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397 | } |
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398 | } else |
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399 | #endif /* IP_REASS_FREE_OLDEST */ |
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400 | { |
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401 | /* @todo: send ICMPv6 time exceeded here? */ |
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402 | /* drop this pbuf */ |
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403 | IP6_FRAG_STATS_INC(ip6_frag.memerr); |
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404 | goto nullreturn; |
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405 | } |
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406 | } |
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407 | |||
408 | /* Overwrite Fragment Header with our own helper struct. */ |
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409 | #if IPV6_FRAG_COPYHEADER |
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410 | if (IPV6_FRAG_REQROOM > 0) { |
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411 | /* Make room for struct ip6_reass_helper (only required if sizeof(void*) > 4). |
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412 | This cannot fail since we already checked when receiving this fragment. */ |
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413 | u8_t hdrerr = pbuf_header_force(p, IPV6_FRAG_REQROOM); |
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414 | LWIP_UNUSED_ARG(hdrerr); /* in case of LWIP_NOASSERT */ |
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415 | LWIP_ASSERT("no room for struct ip6_reass_helper", hdrerr == 0); |
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416 | } |
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417 | #else /* IPV6_FRAG_COPYHEADER */ |
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418 | LWIP_ASSERT("sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN, set IPV6_FRAG_COPYHEADER to 1", |
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419 | sizeof(struct ip6_reass_helper) <= IP6_FRAG_HLEN); |
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420 | #endif /* IPV6_FRAG_COPYHEADER */ |
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421 | |||
422 | /* Prepare the pointer to the helper structure, and its initial values. |
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423 | * Do not yet write to the structure itself, as we still have to make a |
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424 | * backup of the original data, and we should not do that until we know for |
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425 | * sure that we are going to add this packet to the list. */ |
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426 | iprh = (struct ip6_reass_helper *)p->payload; |
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427 | next_pbuf = NULL; |
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428 | end = (u16_t)(start + len); |
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429 | |||
430 | /* find the right place to insert this pbuf */ |
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431 | /* Iterate through until we either get to the end of the list (append), |
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432 | * or we find on with a larger offset (insert). */ |
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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 */ |