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