mbed unsupported / lwip

A version of LWIP, provided for backwards compatibility.

Dependents:   AA_DemoBoard DemoBoard HelloServerDemo DemoBoard_RangeIndicator ... more

trunk/Core/lwIP/core/ipv4/icmp.c@0:5e1631496985, 2012-05-08 (annotated)

Committer:
root@mbed.org
Date:
Tue May 08 15:32:10 2012 +0100
Revision:
0:5e1631496985
initial commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
root@mbed.org 0:5e1631496985 1 /**
root@mbed.org 0:5e1631496985 2 * @file
root@mbed.org 0:5e1631496985 3 * ICMP - Internet Control Message Protocol
root@mbed.org 0:5e1631496985 4 *
root@mbed.org 0:5e1631496985 5 */
root@mbed.org 0:5e1631496985 6
root@mbed.org 0:5e1631496985 7 /*
root@mbed.org 0:5e1631496985 8 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
root@mbed.org 0:5e1631496985 9 * All rights reserved.
root@mbed.org 0:5e1631496985 10 *
root@mbed.org 0:5e1631496985 11 * Redistribution and use in source and binary forms, with or without modification,
root@mbed.org 0:5e1631496985 12 * are permitted provided that the following conditions are met:
root@mbed.org 0:5e1631496985 13 *
root@mbed.org 0:5e1631496985 14 * 1. Redistributions of source code must retain the above copyright notice,
root@mbed.org 0:5e1631496985 15 * this list of conditions and the following disclaimer.
root@mbed.org 0:5e1631496985 16 * 2. Redistributions in binary form must reproduce the above copyright notice,
root@mbed.org 0:5e1631496985 17 * this list of conditions and the following disclaimer in the documentation
root@mbed.org 0:5e1631496985 18 * and/or other materials provided with the distribution.
root@mbed.org 0:5e1631496985 19 * 3. The name of the author may not be used to endorse or promote products
root@mbed.org 0:5e1631496985 20 * derived from this software without specific prior written permission.
root@mbed.org 0:5e1631496985 21 *
root@mbed.org 0:5e1631496985 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
root@mbed.org 0:5e1631496985 23 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
root@mbed.org 0:5e1631496985 24 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
root@mbed.org 0:5e1631496985 25 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
root@mbed.org 0:5e1631496985 26 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
root@mbed.org 0:5e1631496985 27 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
root@mbed.org 0:5e1631496985 28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
root@mbed.org 0:5e1631496985 29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
root@mbed.org 0:5e1631496985 30 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
root@mbed.org 0:5e1631496985 31 * OF SUCH DAMAGE.
root@mbed.org 0:5e1631496985 32 *
root@mbed.org 0:5e1631496985 33 * This file is part of the lwIP TCP/IP stack.
root@mbed.org 0:5e1631496985 34 *
root@mbed.org 0:5e1631496985 35 * Author: Adam Dunkels <adam@sics.se>
root@mbed.org 0:5e1631496985 36 *
root@mbed.org 0:5e1631496985 37 */
root@mbed.org 0:5e1631496985 38
root@mbed.org 0:5e1631496985 39 /* Some ICMP messages should be passed to the transport protocols. This
root@mbed.org 0:5e1631496985 40 is not implemented. */
root@mbed.org 0:5e1631496985 41
root@mbed.org 0:5e1631496985 42 #include "lwip/opt.h"
root@mbed.org 0:5e1631496985 43
root@mbed.org 0:5e1631496985 44 #if LWIP_ICMP /* don't build if not configured for use in lwipopts.h */
root@mbed.org 0:5e1631496985 45
root@mbed.org 0:5e1631496985 46 #include "lwip/icmp.h"
root@mbed.org 0:5e1631496985 47 #include "lwip/inet.h"
root@mbed.org 0:5e1631496985 48 #include "lwip/inet_chksum.h"
root@mbed.org 0:5e1631496985 49 #include "lwip/ip.h"
root@mbed.org 0:5e1631496985 50 #include "lwip/def.h"
root@mbed.org 0:5e1631496985 51 #include "lwip/stats.h"
root@mbed.org 0:5e1631496985 52 #include "lwip/snmp.h"
root@mbed.org 0:5e1631496985 53
root@mbed.org 0:5e1631496985 54 #include <string.h>
root@mbed.org 0:5e1631496985 55
root@mbed.org 0:5e1631496985 56 /** Small optimization: set to 0 if incoming PBUF_POOL pbuf always can be
root@mbed.org 0:5e1631496985 57 * used to modify and send a response packet (and to 1 if this is not the case,
root@mbed.org 0:5e1631496985 58 * e.g. when link header is stripped of when receiving) */
root@mbed.org 0:5e1631496985 59 #ifndef LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
root@mbed.org 0:5e1631496985 60 #define LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN 1
root@mbed.org 0:5e1631496985 61 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
root@mbed.org 0:5e1631496985 62
root@mbed.org 0:5e1631496985 63 /* The amount of data from the original packet to return in a dest-unreachable */
root@mbed.org 0:5e1631496985 64 #define ICMP_DEST_UNREACH_DATASIZE 8
root@mbed.org 0:5e1631496985 65
root@mbed.org 0:5e1631496985 66 static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code);
root@mbed.org 0:5e1631496985 67
root@mbed.org 0:5e1631496985 68 /**
root@mbed.org 0:5e1631496985 69 * Processes ICMP input packets, called from ip_input().
root@mbed.org 0:5e1631496985 70 *
root@mbed.org 0:5e1631496985 71 * Currently only processes icmp echo requests and sends
root@mbed.org 0:5e1631496985 72 * out the echo response.
root@mbed.org 0:5e1631496985 73 *
root@mbed.org 0:5e1631496985 74 * @param p the icmp echo request packet, p->payload pointing to the ip header
root@mbed.org 0:5e1631496985 75 * @param inp the netif on which this packet was received
root@mbed.org 0:5e1631496985 76 */
root@mbed.org 0:5e1631496985 77 void
root@mbed.org 0:5e1631496985 78 icmp_input(struct pbuf *p, struct netif *inp)
root@mbed.org 0:5e1631496985 79 {
root@mbed.org 0:5e1631496985 80 u8_t type;
root@mbed.org 0:5e1631496985 81 #ifdef LWIP_DEBUG
root@mbed.org 0:5e1631496985 82 u8_t code;
root@mbed.org 0:5e1631496985 83 #endif /* LWIP_DEBUG */
root@mbed.org 0:5e1631496985 84 struct icmp_echo_hdr *iecho;
root@mbed.org 0:5e1631496985 85 struct ip_hdr *iphdr;
root@mbed.org 0:5e1631496985 86 struct ip_addr tmpaddr;
root@mbed.org 0:5e1631496985 87 s16_t hlen;
root@mbed.org 0:5e1631496985 88
root@mbed.org 0:5e1631496985 89 ICMP_STATS_INC(icmp.recv);
root@mbed.org 0:5e1631496985 90 snmp_inc_icmpinmsgs();
root@mbed.org 0:5e1631496985 91
root@mbed.org 0:5e1631496985 92
root@mbed.org 0:5e1631496985 93 iphdr = (struct ip_hdr *)p->payload;
root@mbed.org 0:5e1631496985 94 hlen = IPH_HL(iphdr) * 4;
root@mbed.org 0:5e1631496985 95 if (pbuf_header(p, -hlen) || (p->tot_len < sizeof(u16_t)*2)) {
root@mbed.org 0:5e1631496985 96 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
root@mbed.org 0:5e1631496985 97 goto lenerr;
root@mbed.org 0:5e1631496985 98 }
root@mbed.org 0:5e1631496985 99
root@mbed.org 0:5e1631496985 100 type = *((u8_t *)p->payload);
root@mbed.org 0:5e1631496985 101 #ifdef LWIP_DEBUG
root@mbed.org 0:5e1631496985 102 code = *(((u8_t *)p->payload)+1);
root@mbed.org 0:5e1631496985 103 #endif /* LWIP_DEBUG */
root@mbed.org 0:5e1631496985 104 switch (type) {
root@mbed.org 0:5e1631496985 105 case ICMP_ECHO:
root@mbed.org 0:5e1631496985 106 #if !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
root@mbed.org 0:5e1631496985 107 {
root@mbed.org 0:5e1631496985 108 int accepted = 1;
root@mbed.org 0:5e1631496985 109 #if !LWIP_MULTICAST_PING
root@mbed.org 0:5e1631496985 110 /* multicast destination address? */
root@mbed.org 0:5e1631496985 111 if (ip_addr_ismulticast(&iphdr->dest)) {
root@mbed.org 0:5e1631496985 112 accepted = 0;
root@mbed.org 0:5e1631496985 113 }
root@mbed.org 0:5e1631496985 114 #endif /* LWIP_MULTICAST_PING */
root@mbed.org 0:5e1631496985 115 #if !LWIP_BROADCAST_PING
root@mbed.org 0:5e1631496985 116 /* broadcast destination address? */
root@mbed.org 0:5e1631496985 117 if (ip_addr_isbroadcast(&iphdr->dest, inp)) {
root@mbed.org 0:5e1631496985 118 accepted = 0;
root@mbed.org 0:5e1631496985 119 }
root@mbed.org 0:5e1631496985 120 #endif /* LWIP_BROADCAST_PING */
root@mbed.org 0:5e1631496985 121 /* broadcast or multicast destination address not acceptd? */
root@mbed.org 0:5e1631496985 122 if (!accepted) {
root@mbed.org 0:5e1631496985 123 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
root@mbed.org 0:5e1631496985 124 ICMP_STATS_INC(icmp.err);
root@mbed.org 0:5e1631496985 125 pbuf_free(p);
root@mbed.org 0:5e1631496985 126 return;
root@mbed.org 0:5e1631496985 127 }
root@mbed.org 0:5e1631496985 128 }
root@mbed.org 0:5e1631496985 129 #endif /* !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
root@mbed.org 0:5e1631496985 130 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
root@mbed.org 0:5e1631496985 131 if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
root@mbed.org 0:5e1631496985 132 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
root@mbed.org 0:5e1631496985 133 goto lenerr;
root@mbed.org 0:5e1631496985 134 }
root@mbed.org 0:5e1631496985 135 if (inet_chksum_pbuf(p) != 0) {
root@mbed.org 0:5e1631496985 136 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
root@mbed.org 0:5e1631496985 137 pbuf_free(p);
root@mbed.org 0:5e1631496985 138 ICMP_STATS_INC(icmp.chkerr);
root@mbed.org 0:5e1631496985 139 snmp_inc_icmpinerrors();
root@mbed.org 0:5e1631496985 140 return;
root@mbed.org 0:5e1631496985 141 }
root@mbed.org 0:5e1631496985 142 #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
root@mbed.org 0:5e1631496985 143 if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
root@mbed.org 0:5e1631496985 144 /* p is not big enough to contain link headers
root@mbed.org 0:5e1631496985 145 * allocate a new one and copy p into it
root@mbed.org 0:5e1631496985 146 */
root@mbed.org 0:5e1631496985 147 struct pbuf *r;
root@mbed.org 0:5e1631496985 148 /* switch p->payload to ip header */
root@mbed.org 0:5e1631496985 149 if (pbuf_header(p, hlen)) {
root@mbed.org 0:5e1631496985 150 LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
root@mbed.org 0:5e1631496985 151 goto memerr;
root@mbed.org 0:5e1631496985 152 }
root@mbed.org 0:5e1631496985 153 /* allocate new packet buffer with space for link headers */
root@mbed.org 0:5e1631496985 154 r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
root@mbed.org 0:5e1631496985 155 if (r == NULL) {
root@mbed.org 0:5e1631496985 156 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
root@mbed.org 0:5e1631496985 157 goto memerr;
root@mbed.org 0:5e1631496985 158 }
root@mbed.org 0:5e1631496985 159 LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
root@mbed.org 0:5e1631496985 160 (r->len >= hlen + sizeof(struct icmp_echo_hdr)));
root@mbed.org 0:5e1631496985 161 /* copy the whole packet including ip header */
root@mbed.org 0:5e1631496985 162 if (pbuf_copy(r, p) != ERR_OK) {
root@mbed.org 0:5e1631496985 163 LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
root@mbed.org 0:5e1631496985 164 goto memerr;
root@mbed.org 0:5e1631496985 165 }
root@mbed.org 0:5e1631496985 166 iphdr = (struct ip_hdr *)r->payload;
root@mbed.org 0:5e1631496985 167 /* switch r->payload back to icmp header */
root@mbed.org 0:5e1631496985 168 if (pbuf_header(r, -hlen)) {
root@mbed.org 0:5e1631496985 169 LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
root@mbed.org 0:5e1631496985 170 goto memerr;
root@mbed.org 0:5e1631496985 171 }
root@mbed.org 0:5e1631496985 172 /* free the original p */
root@mbed.org 0:5e1631496985 173 pbuf_free(p);
root@mbed.org 0:5e1631496985 174 /* we now have an identical copy of p that has room for link headers */
root@mbed.org 0:5e1631496985 175 p = r;
root@mbed.org 0:5e1631496985 176 } else {
root@mbed.org 0:5e1631496985 177 /* restore p->payload to point to icmp header */
root@mbed.org 0:5e1631496985 178 if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
root@mbed.org 0:5e1631496985 179 LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
root@mbed.org 0:5e1631496985 180 goto memerr;
root@mbed.org 0:5e1631496985 181 }
root@mbed.org 0:5e1631496985 182 }
root@mbed.org 0:5e1631496985 183 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
root@mbed.org 0:5e1631496985 184 /* At this point, all checks are OK. */
root@mbed.org 0:5e1631496985 185 /* We generate an answer by switching the dest and src ip addresses,
root@mbed.org 0:5e1631496985 186 * setting the icmp type to ECHO_RESPONSE and updating the checksum. */
root@mbed.org 0:5e1631496985 187 iecho = (struct icmp_echo_hdr *)p->payload;
root@mbed.org 0:5e1631496985 188 tmpaddr.addr = iphdr->src.addr;
root@mbed.org 0:5e1631496985 189 iphdr->src.addr = iphdr->dest.addr;
root@mbed.org 0:5e1631496985 190 iphdr->dest.addr = tmpaddr.addr;
root@mbed.org 0:5e1631496985 191 ICMPH_TYPE_SET(iecho, ICMP_ER);
root@mbed.org 0:5e1631496985 192 /* adjust the checksum */
root@mbed.org 0:5e1631496985 193 if (iecho->chksum >= htons(0xffff - (ICMP_ECHO << 8))) {
root@mbed.org 0:5e1631496985 194 iecho->chksum += htons(ICMP_ECHO << 8) + 1;
root@mbed.org 0:5e1631496985 195 } else {
root@mbed.org 0:5e1631496985 196 iecho->chksum += htons(ICMP_ECHO << 8);
root@mbed.org 0:5e1631496985 197 }
root@mbed.org 0:5e1631496985 198
root@mbed.org 0:5e1631496985 199 /* Set the correct TTL and recalculate the header checksum. */
root@mbed.org 0:5e1631496985 200 IPH_TTL_SET(iphdr, ICMP_TTL);
root@mbed.org 0:5e1631496985 201 IPH_CHKSUM_SET(iphdr, 0);
root@mbed.org 0:5e1631496985 202 #if CHECKSUM_GEN_IP
root@mbed.org 0:5e1631496985 203 IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
root@mbed.org 0:5e1631496985 204 #endif /* CHECKSUM_GEN_IP */
root@mbed.org 0:5e1631496985 205
root@mbed.org 0:5e1631496985 206 ICMP_STATS_INC(icmp.xmit);
root@mbed.org 0:5e1631496985 207 /* increase number of messages attempted to send */
root@mbed.org 0:5e1631496985 208 snmp_inc_icmpoutmsgs();
root@mbed.org 0:5e1631496985 209 /* increase number of echo replies attempted to send */
root@mbed.org 0:5e1631496985 210 snmp_inc_icmpoutechoreps();
root@mbed.org 0:5e1631496985 211
root@mbed.org 0:5e1631496985 212 if(pbuf_header(p, hlen)) {
root@mbed.org 0:5e1631496985 213 LWIP_ASSERT("Can't move over header in packet", 0);
root@mbed.org 0:5e1631496985 214 } else {
root@mbed.org 0:5e1631496985 215 err_t ret;
root@mbed.org 0:5e1631496985 216 ret = ip_output_if(p, &(iphdr->src), IP_HDRINCL,
root@mbed.org 0:5e1631496985 217 ICMP_TTL, 0, IP_PROTO_ICMP, inp);
root@mbed.org 0:5e1631496985 218 if (ret != ERR_OK) {
root@mbed.org 0:5e1631496985 219 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
root@mbed.org 0:5e1631496985 220 }
root@mbed.org 0:5e1631496985 221 }
root@mbed.org 0:5e1631496985 222 break;
root@mbed.org 0:5e1631496985 223 default:
root@mbed.org 0:5e1631496985 224 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
root@mbed.org 0:5e1631496985 225 (s16_t)type, (s16_t)code));
root@mbed.org 0:5e1631496985 226 ICMP_STATS_INC(icmp.proterr);
root@mbed.org 0:5e1631496985 227 ICMP_STATS_INC(icmp.drop);
root@mbed.org 0:5e1631496985 228 }
root@mbed.org 0:5e1631496985 229 pbuf_free(p);
root@mbed.org 0:5e1631496985 230 return;
root@mbed.org 0:5e1631496985 231 lenerr:
root@mbed.org 0:5e1631496985 232 pbuf_free(p);
root@mbed.org 0:5e1631496985 233 ICMP_STATS_INC(icmp.lenerr);
root@mbed.org 0:5e1631496985 234 snmp_inc_icmpinerrors();
root@mbed.org 0:5e1631496985 235 return;
root@mbed.org 0:5e1631496985 236 #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
root@mbed.org 0:5e1631496985 237 memerr:
root@mbed.org 0:5e1631496985 238 pbuf_free(p);
root@mbed.org 0:5e1631496985 239 ICMP_STATS_INC(icmp.err);
root@mbed.org 0:5e1631496985 240 snmp_inc_icmpinerrors();
root@mbed.org 0:5e1631496985 241 return;
root@mbed.org 0:5e1631496985 242 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
root@mbed.org 0:5e1631496985 243 }
root@mbed.org 0:5e1631496985 244
root@mbed.org 0:5e1631496985 245 /**
root@mbed.org 0:5e1631496985 246 * Send an icmp 'destination unreachable' packet, called from ip_input() if
root@mbed.org 0:5e1631496985 247 * the transport layer protocol is unknown and from udp_input() if the local
root@mbed.org 0:5e1631496985 248 * port is not bound.
root@mbed.org 0:5e1631496985 249 *
root@mbed.org 0:5e1631496985 250 * @param p the input packet for which the 'unreachable' should be sent,
root@mbed.org 0:5e1631496985 251 * p->payload pointing to the IP header
root@mbed.org 0:5e1631496985 252 * @param t type of the 'unreachable' packet
root@mbed.org 0:5e1631496985 253 */
root@mbed.org 0:5e1631496985 254 void
root@mbed.org 0:5e1631496985 255 icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t)
root@mbed.org 0:5e1631496985 256 {
root@mbed.org 0:5e1631496985 257 icmp_send_response(p, ICMP_DUR, t);
root@mbed.org 0:5e1631496985 258 }
root@mbed.org 0:5e1631496985 259
root@mbed.org 0:5e1631496985 260 #if IP_FORWARD || IP_REASSEMBLY
root@mbed.org 0:5e1631496985 261 /**
root@mbed.org 0:5e1631496985 262 * Send a 'time exceeded' packet, called from ip_forward() if TTL is 0.
root@mbed.org 0:5e1631496985 263 *
root@mbed.org 0:5e1631496985 264 * @param p the input packet for which the 'time exceeded' should be sent,
root@mbed.org 0:5e1631496985 265 * p->payload pointing to the IP header
root@mbed.org 0:5e1631496985 266 * @param t type of the 'time exceeded' packet
root@mbed.org 0:5e1631496985 267 */
root@mbed.org 0:5e1631496985 268 void
root@mbed.org 0:5e1631496985 269 icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t)
root@mbed.org 0:5e1631496985 270 {
root@mbed.org 0:5e1631496985 271 icmp_send_response(p, ICMP_TE, t);
root@mbed.org 0:5e1631496985 272 }
root@mbed.org 0:5e1631496985 273
root@mbed.org 0:5e1631496985 274 #endif /* IP_FORWARD || IP_REASSEMBLY */
root@mbed.org 0:5e1631496985 275
root@mbed.org 0:5e1631496985 276 /**
root@mbed.org 0:5e1631496985 277 * Send an icmp packet in response to an incoming packet.
root@mbed.org 0:5e1631496985 278 *
root@mbed.org 0:5e1631496985 279 * @param p the input packet for which the 'unreachable' should be sent,
root@mbed.org 0:5e1631496985 280 * p->payload pointing to the IP header
root@mbed.org 0:5e1631496985 281 * @param type Type of the ICMP header
root@mbed.org 0:5e1631496985 282 * @param code Code of the ICMP header
root@mbed.org 0:5e1631496985 283 */
root@mbed.org 0:5e1631496985 284 static void
root@mbed.org 0:5e1631496985 285 icmp_send_response(struct pbuf *p, u8_t type, u8_t code)
root@mbed.org 0:5e1631496985 286 {
root@mbed.org 0:5e1631496985 287 struct pbuf *q;
root@mbed.org 0:5e1631496985 288 struct ip_hdr *iphdr;
root@mbed.org 0:5e1631496985 289 /* we can use the echo header here */
root@mbed.org 0:5e1631496985 290 struct icmp_echo_hdr *icmphdr;
root@mbed.org 0:5e1631496985 291
root@mbed.org 0:5e1631496985 292 /* ICMP header + IP header + 8 bytes of data */
root@mbed.org 0:5e1631496985 293 q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE,
root@mbed.org 0:5e1631496985 294 PBUF_RAM);
root@mbed.org 0:5e1631496985 295 if (q == NULL) {
root@mbed.org 0:5e1631496985 296 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n"));
root@mbed.org 0:5e1631496985 297 return;
root@mbed.org 0:5e1631496985 298 }
root@mbed.org 0:5e1631496985 299 LWIP_ASSERT("check that first pbuf can hold icmp message",
root@mbed.org 0:5e1631496985 300 (q->len >= (sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE)));
root@mbed.org 0:5e1631496985 301
root@mbed.org 0:5e1631496985 302 iphdr = (struct ip_hdr *)p->payload;
root@mbed.org 0:5e1631496985 303 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));
root@mbed.org 0:5e1631496985 304 ip_addr_debug_print(ICMP_DEBUG, &(iphdr->src));
root@mbed.org 0:5e1631496985 305 LWIP_DEBUGF(ICMP_DEBUG, (" to "));
root@mbed.org 0:5e1631496985 306 ip_addr_debug_print(ICMP_DEBUG, &(iphdr->dest));
root@mbed.org 0:5e1631496985 307 LWIP_DEBUGF(ICMP_DEBUG, ("\n"));
root@mbed.org 0:5e1631496985 308
root@mbed.org 0:5e1631496985 309 icmphdr = (struct icmp_echo_hdr *)q->payload;
root@mbed.org 0:5e1631496985 310 icmphdr->type = type;
root@mbed.org 0:5e1631496985 311 icmphdr->code = code;
root@mbed.org 0:5e1631496985 312 icmphdr->id = 0;
root@mbed.org 0:5e1631496985 313 icmphdr->seqno = 0;
root@mbed.org 0:5e1631496985 314
root@mbed.org 0:5e1631496985 315 /* copy fields from original packet */
root@mbed.org 0:5e1631496985 316 SMEMCPY((u8_t *)q->payload + sizeof(struct icmp_echo_hdr), (u8_t *)p->payload,
root@mbed.org 0:5e1631496985 317 IP_HLEN + ICMP_DEST_UNREACH_DATASIZE);
root@mbed.org 0:5e1631496985 318
root@mbed.org 0:5e1631496985 319 /* calculate checksum */
root@mbed.org 0:5e1631496985 320 icmphdr->chksum = 0;
root@mbed.org 0:5e1631496985 321 icmphdr->chksum = inet_chksum(icmphdr, q->len);
root@mbed.org 0:5e1631496985 322 ICMP_STATS_INC(icmp.xmit);
root@mbed.org 0:5e1631496985 323 /* increase number of messages attempted to send */
root@mbed.org 0:5e1631496985 324 snmp_inc_icmpoutmsgs();
root@mbed.org 0:5e1631496985 325 /* increase number of destination unreachable messages attempted to send */
root@mbed.org 0:5e1631496985 326 snmp_inc_icmpouttimeexcds();
root@mbed.org 0:5e1631496985 327 ip_output(q, NULL, &(iphdr->src), ICMP_TTL, 0, IP_PROTO_ICMP);
root@mbed.org 0:5e1631496985 328 pbuf_free(q);
root@mbed.org 0:5e1631496985 329 }
root@mbed.org 0:5e1631496985 330
root@mbed.org 0:5e1631496985 331 #endif /* LWIP_ICMP */