1 | /**
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2 | * @file
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3 | * ICMP - Internet Control Message Protocol
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4 | *
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5 | */
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6 |
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7 | /*
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8 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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9 | * All rights reserved.
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10 | *
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11 | * Redistribution and use in source and binary forms, with or without modification,
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12 | * are permitted provided that the following conditions are met:
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13 | *
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14 | * 1. Redistributions of source code must retain the above copyright notice,
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15 | * this list of conditions and the following disclaimer.
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16 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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17 | * this list of conditions and the following disclaimer in the documentation
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18 | * and/or other materials provided with the distribution.
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19 | * 3. The name of the author may not be used to endorse or promote products
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20 | * derived from this software without specific prior written permission.
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21 | *
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22 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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23 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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24 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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25 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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26 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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27 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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30 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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31 | * OF SUCH DAMAGE.
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32 | *
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33 | * This file is part of the lwIP TCP/IP stack.
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34 | *
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35 | * Author: Adam Dunkels <adam@sics.se>
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36 | *
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37 | */
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38 |
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39 | /* Some ICMP messages should be passed to the transport protocols. This
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40 | is not implemented. */
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41 |
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42 | #include "lwip/opt.h"
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43 |
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44 | #if LWIP_IPV4 && LWIP_ICMP /* don't build if not configured for use in lwipopts.h */
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45 |
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46 | #include "lwip/icmp.h"
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47 | #include "lwip/inet_chksum.h"
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48 | #include "lwip/ip.h"
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49 | #include "lwip/def.h"
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50 | #include "lwip/stats.h"
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51 |
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52 | #include <string.h>
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53 |
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54 | #ifdef LWIP_HOOK_FILENAME
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55 | #include LWIP_HOOK_FILENAME
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56 | #endif
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57 |
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58 | /** Small optimization: set to 0 if incoming PBUF_POOL pbuf always can be
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59 | * used to modify and send a response packet (and to 1 if this is not the case,
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60 | * e.g. when link header is stripped off when receiving) */
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61 | #ifndef LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
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62 | #define LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN 1
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63 | #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
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64 |
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65 | /* The amount of data from the original packet to return in a dest-unreachable */
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66 | #define ICMP_DEST_UNREACH_DATASIZE 8
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67 |
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68 | static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code);
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69 |
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70 | /**
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71 | * Processes ICMP input packets, called from ip_input().
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72 | *
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73 | * Currently only processes icmp echo requests and sends
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74 | * out the echo response.
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75 | *
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76 | * @param p the icmp echo request packet, p->payload pointing to the icmp header
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77 | * @param inp the netif on which this packet was received
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78 | */
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79 | void
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80 | icmp_input(struct pbuf *p, struct netif *inp)
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81 | {
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82 | u8_t type;
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83 | #ifdef LWIP_DEBUG
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84 | u8_t code;
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85 | #endif /* LWIP_DEBUG */
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86 | struct icmp_echo_hdr *iecho;
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87 | const struct ip_hdr *iphdr_in;
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88 | u16_t hlen;
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89 | const ip4_addr_t *src;
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90 |
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91 | ICMP_STATS_INC(icmp.recv);
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92 | MIB2_STATS_INC(mib2.icmpinmsgs);
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93 |
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94 | iphdr_in = ip4_current_header();
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95 | hlen = IPH_HL_BYTES(iphdr_in);
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96 | if (hlen < IP_HLEN) {
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97 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short IP header (%"S16_F" bytes) received\n", hlen));
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98 | goto lenerr;
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99 | }
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100 | if (p->len < sizeof(u16_t) * 2) {
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101 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
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102 | goto lenerr;
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103 | }
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104 |
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105 | type = *((u8_t *)p->payload);
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106 | #ifdef LWIP_DEBUG
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107 | code = *(((u8_t *)p->payload) + 1);
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108 | /* if debug is enabled but debug statement below is somehow disabled: */
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109 | LWIP_UNUSED_ARG(code);
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110 | #endif /* LWIP_DEBUG */
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111 | switch (type) {
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112 | case ICMP_ER:
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113 | /* This is OK, echo reply might have been parsed by a raw PCB
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114 | (as obviously, an echo request has been sent, too). */
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115 | MIB2_STATS_INC(mib2.icmpinechoreps);
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116 | break;
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117 | case ICMP_ECHO:
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118 | MIB2_STATS_INC(mib2.icmpinechos);
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119 | src = ip4_current_dest_addr();
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120 | /* multicast destination address? */
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121 | if (ip4_addr_ismulticast(ip4_current_dest_addr())) {
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122 | #if LWIP_MULTICAST_PING
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123 | /* For multicast, use address of receiving interface as source address */
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124 | src = netif_ip4_addr(inp);
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125 | #else /* LWIP_MULTICAST_PING */
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126 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast pings\n"));
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127 | goto icmperr;
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128 | #endif /* LWIP_MULTICAST_PING */
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129 | }
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130 | /* broadcast destination address? */
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131 | if (ip4_addr_isbroadcast(ip4_current_dest_addr(), ip_current_netif())) {
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132 | #if LWIP_BROADCAST_PING
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133 | /* For broadcast, use address of receiving interface as source address */
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134 | src = netif_ip4_addr(inp);
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135 | #else /* LWIP_BROADCAST_PING */
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136 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to broadcast pings\n"));
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137 | goto icmperr;
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138 | #endif /* LWIP_BROADCAST_PING */
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139 | }
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140 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
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141 | if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
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142 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
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143 | goto lenerr;
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144 | }
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145 | #if CHECKSUM_CHECK_ICMP
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146 | IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_CHECK_ICMP) {
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147 | if (inet_chksum_pbuf(p) != 0) {
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148 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
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149 | pbuf_free(p);
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150 | ICMP_STATS_INC(icmp.chkerr);
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151 | MIB2_STATS_INC(mib2.icmpinerrors);
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152 | return;
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153 | }
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154 | }
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155 | #endif
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156 | #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
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157 | if (pbuf_add_header(p, hlen + PBUF_LINK_HLEN + PBUF_LINK_ENCAPSULATION_HLEN)) {
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158 | /* p is not big enough to contain link headers
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159 | * allocate a new one and copy p into it
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160 | */
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161 | struct pbuf *r;
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162 | u16_t alloc_len = (u16_t)(p->tot_len + hlen);
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163 | if (alloc_len < p->tot_len) {
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164 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed (tot_len overflow)\n"));
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165 | goto icmperr;
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166 | }
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167 | /* allocate new packet buffer with space for link headers */
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168 | r = pbuf_alloc(PBUF_LINK, alloc_len, PBUF_RAM);
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169 | if (r == NULL) {
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170 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
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171 | goto icmperr;
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172 | }
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173 | if (r->len < hlen + sizeof(struct icmp_echo_hdr)) {
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174 | LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("first pbuf cannot hold the ICMP header"));
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175 | pbuf_free(r);
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176 | goto icmperr;
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177 | }
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178 | /* copy the ip header */
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179 | MEMCPY(r->payload, iphdr_in, hlen);
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180 | /* switch r->payload back to icmp header (cannot fail) */
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181 | if (pbuf_remove_header(r, hlen)) {
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182 | LWIP_ASSERT("icmp_input: moving r->payload to icmp header failed\n", 0);
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183 | pbuf_free(r);
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184 | goto icmperr;
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185 | }
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186 | /* copy the rest of the packet without ip header */
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187 | if (pbuf_copy(r, p) != ERR_OK) {
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188 | LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("icmp_input: copying to new pbuf failed"));
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189 | pbuf_free(r);
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190 | goto icmperr;
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191 | }
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192 | /* free the original p */
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193 | pbuf_free(p);
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194 | /* we now have an identical copy of p that has room for link headers */
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195 | p = r;
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196 | } else {
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197 | /* restore p->payload to point to icmp header (cannot fail) */
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198 | if (pbuf_remove_header(p, hlen + PBUF_LINK_HLEN + PBUF_LINK_ENCAPSULATION_HLEN)) {
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199 | LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
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200 | goto icmperr;
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201 | }
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202 | }
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203 | #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
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204 | /* At this point, all checks are OK. */
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205 | /* We generate an answer by switching the dest and src ip addresses,
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206 | * setting the icmp type to ECHO_RESPONSE and updating the checksum. */
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207 | iecho = (struct icmp_echo_hdr *)p->payload;
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208 | if (pbuf_add_header(p, hlen)) {
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209 | LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("Can't move over header in packet"));
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210 | } else {
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211 | err_t ret;
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212 | struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
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213 | ip4_addr_copy(iphdr->src, *src);
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214 | ip4_addr_copy(iphdr->dest, *ip4_current_src_addr());
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215 | ICMPH_TYPE_SET(iecho, ICMP_ER);
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216 | #if CHECKSUM_GEN_ICMP
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217 | IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_GEN_ICMP) {
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218 | /* adjust the checksum */
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219 | if (iecho->chksum > PP_HTONS(0xffffU - (ICMP_ECHO << 8))) {
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220 | iecho->chksum = (u16_t)(iecho->chksum + PP_HTONS((u16_t)(ICMP_ECHO << 8)) + 1);
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221 | } else {
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222 | iecho->chksum = (u16_t)(iecho->chksum + PP_HTONS(ICMP_ECHO << 8));
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223 | }
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224 | }
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225 | #if LWIP_CHECKSUM_CTRL_PER_NETIF
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226 | else {
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227 | iecho->chksum = 0;
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228 | }
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229 | #endif /* LWIP_CHECKSUM_CTRL_PER_NETIF */
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230 | #else /* CHECKSUM_GEN_ICMP */
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231 | iecho->chksum = 0;
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232 | #endif /* CHECKSUM_GEN_ICMP */
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233 |
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234 | /* Set the correct TTL and recalculate the header checksum. */
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235 | IPH_TTL_SET(iphdr, ICMP_TTL);
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236 | IPH_CHKSUM_SET(iphdr, 0);
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237 | #if CHECKSUM_GEN_IP
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238 | IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_GEN_IP) {
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239 | IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, hlen));
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240 | }
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241 | #endif /* CHECKSUM_GEN_IP */
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242 |
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243 | ICMP_STATS_INC(icmp.xmit);
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244 | /* increase number of messages attempted to send */
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245 | MIB2_STATS_INC(mib2.icmpoutmsgs);
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246 | /* increase number of echo replies attempted to send */
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247 | MIB2_STATS_INC(mib2.icmpoutechoreps);
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248 |
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249 | /* send an ICMP packet */
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250 | ret = ip4_output_if(p, src, LWIP_IP_HDRINCL,
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251 | ICMP_TTL, 0, IP_PROTO_ICMP, inp);
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252 | if (ret != ERR_OK) {
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253 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %s\n", lwip_strerr(ret)));
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254 | }
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255 | }
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256 | break;
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257 | default:
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258 | if (type == ICMP_DUR) {
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259 | MIB2_STATS_INC(mib2.icmpindestunreachs);
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260 | } else if (type == ICMP_TE) {
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261 | MIB2_STATS_INC(mib2.icmpintimeexcds);
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262 | } else if (type == ICMP_PP) {
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263 | MIB2_STATS_INC(mib2.icmpinparmprobs);
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264 | } else if (type == ICMP_SQ) {
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265 | MIB2_STATS_INC(mib2.icmpinsrcquenchs);
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266 | } else if (type == ICMP_RD) {
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267 | MIB2_STATS_INC(mib2.icmpinredirects);
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268 | } else if (type == ICMP_TS) {
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269 | MIB2_STATS_INC(mib2.icmpintimestamps);
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270 | } else if (type == ICMP_TSR) {
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271 | MIB2_STATS_INC(mib2.icmpintimestampreps);
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272 | } else if (type == ICMP_AM) {
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273 | MIB2_STATS_INC(mib2.icmpinaddrmasks);
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274 | } else if (type == ICMP_AMR) {
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275 | MIB2_STATS_INC(mib2.icmpinaddrmaskreps);
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276 | }
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277 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
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278 | (s16_t)type, (s16_t)code));
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279 | ICMP_STATS_INC(icmp.proterr);
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280 | ICMP_STATS_INC(icmp.drop);
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281 | }
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282 | pbuf_free(p);
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283 | return;
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284 | lenerr:
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285 | pbuf_free(p);
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286 | ICMP_STATS_INC(icmp.lenerr);
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287 | MIB2_STATS_INC(mib2.icmpinerrors);
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288 | return;
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289 | #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN || !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
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290 | icmperr:
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291 | pbuf_free(p);
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292 | ICMP_STATS_INC(icmp.err);
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293 | MIB2_STATS_INC(mib2.icmpinerrors);
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294 | return;
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295 | #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN || !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
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296 | }
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297 |
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298 | /**
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299 | * Send an icmp 'destination unreachable' packet, called from ip_input() if
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300 | * the transport layer protocol is unknown and from udp_input() if the local
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301 | * port is not bound.
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302 | *
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303 | * @param p the input packet for which the 'unreachable' should be sent,
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304 | * p->payload pointing to the IP header
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305 | * @param t type of the 'unreachable' packet
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306 | */
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307 | void
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308 | icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t)
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309 | {
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310 | MIB2_STATS_INC(mib2.icmpoutdestunreachs);
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311 | icmp_send_response(p, ICMP_DUR, t);
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312 | }
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313 |
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314 | #if IP_FORWARD || IP_REASSEMBLY
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315 | /**
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316 | * Send a 'time exceeded' packet, called from ip_forward() if TTL is 0.
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317 | *
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318 | * @param p the input packet for which the 'time exceeded' should be sent,
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319 | * p->payload pointing to the IP header
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320 | * @param t type of the 'time exceeded' packet
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321 | */
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322 | void
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323 | icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t)
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324 | {
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325 | MIB2_STATS_INC(mib2.icmpouttimeexcds);
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326 | icmp_send_response(p, ICMP_TE, t);
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327 | }
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328 |
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329 | #endif /* IP_FORWARD || IP_REASSEMBLY */
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330 |
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331 | /**
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332 | * Send an icmp packet in response to an incoming packet.
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333 | *
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334 | * @param p the input packet for which the 'unreachable' should be sent,
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335 | * p->payload pointing to the IP header
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336 | * @param type Type of the ICMP header
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337 | * @param code Code of the ICMP header
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338 | */
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339 | static void
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340 | icmp_send_response(struct pbuf *p, u8_t type, u8_t code)
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341 | {
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342 | struct pbuf *q;
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343 | struct ip_hdr *iphdr;
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344 | /* we can use the echo header here */
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345 | struct icmp_echo_hdr *icmphdr;
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346 | ip4_addr_t iphdr_src;
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347 | struct netif *netif;
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348 |
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349 | /* increase number of messages attempted to send */
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350 | MIB2_STATS_INC(mib2.icmpoutmsgs);
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351 |
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352 | /* ICMP header + IP header + 8 bytes of data */
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353 | q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE,
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354 | PBUF_RAM);
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355 | if (q == NULL) {
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356 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n"));
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357 | MIB2_STATS_INC(mib2.icmpouterrors);
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358 | return;
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359 | }
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360 | LWIP_ASSERT("check that first pbuf can hold icmp message",
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361 | (q->len >= (sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE)));
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362 |
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363 | iphdr = (struct ip_hdr *)p->payload;
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364 | LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));
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365 | ip4_addr_debug_print_val(ICMP_DEBUG, iphdr->src);
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366 | LWIP_DEBUGF(ICMP_DEBUG, (" to "));
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367 | ip4_addr_debug_print_val(ICMP_DEBUG, iphdr->dest);
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368 | LWIP_DEBUGF(ICMP_DEBUG, ("\n"));
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369 |
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370 | icmphdr = (struct icmp_echo_hdr *)q->payload;
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371 | icmphdr->type = type;
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372 | icmphdr->code = code;
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373 | icmphdr->id = 0;
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374 | icmphdr->seqno = 0;
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375 |
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376 | /* copy fields from original packet */
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377 | SMEMCPY((u8_t *)q->payload + sizeof(struct icmp_echo_hdr), (u8_t *)p->payload,
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378 | IP_HLEN + ICMP_DEST_UNREACH_DATASIZE);
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379 |
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380 | ip4_addr_copy(iphdr_src, iphdr->src);
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381 | #ifdef LWIP_HOOK_IP4_ROUTE_SRC
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382 | {
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383 | ip4_addr_t iphdr_dst;
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384 | ip4_addr_copy(iphdr_dst, iphdr->dest);
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385 | netif = ip4_route_src(&iphdr_dst, &iphdr_src);
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386 | }
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387 | #else
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388 | netif = ip4_route(&iphdr_src);
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389 | #endif
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390 | if (netif != NULL) {
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391 | /* calculate checksum */
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392 | icmphdr->chksum = 0;
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393 | #if CHECKSUM_GEN_ICMP
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394 | IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_ICMP) {
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395 | icmphdr->chksum = inet_chksum(icmphdr, q->len);
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396 | }
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397 | #endif
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398 | ICMP_STATS_INC(icmp.xmit);
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399 | ip4_output_if(q, NULL, &iphdr_src, ICMP_TTL, 0, IP_PROTO_ICMP, netif);
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400 | }
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401 | pbuf_free(q);
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402 | }
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403 |
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404 | #endif /* LWIP_IPV4 && LWIP_ICMP */
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