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core/ipv4/icmp.c@0:51ac1d130fd4, 2012-06-22 (annotated)

Committer:
mbed_official
Date:
Fri Jun 22 09:25:39 2012 +0000
Revision:
0:51ac1d130fd4
Initial import from lwip-1.4.0: http://download.savannah.gnu.org/releases/lwip/lwip-1.4.0.zip

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 0:51ac1d130fd4 1 /**
mbed_official 0:51ac1d130fd4 2 * @file
mbed_official 0:51ac1d130fd4 3 * ICMP - Internet Control Message Protocol
mbed_official 0:51ac1d130fd4 4 *
mbed_official 0:51ac1d130fd4 5 */
mbed_official 0:51ac1d130fd4 6
mbed_official 0:51ac1d130fd4 7 /*
mbed_official 0:51ac1d130fd4 8 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
mbed_official 0:51ac1d130fd4 9 * All rights reserved.
mbed_official 0:51ac1d130fd4 10 *
mbed_official 0:51ac1d130fd4 11 * Redistribution and use in source and binary forms, with or without modification,
mbed_official 0:51ac1d130fd4 12 * are permitted provided that the following conditions are met:
mbed_official 0:51ac1d130fd4 13 *
mbed_official 0:51ac1d130fd4 14 * 1. Redistributions of source code must retain the above copyright notice,
mbed_official 0:51ac1d130fd4 15 * this list of conditions and the following disclaimer.
mbed_official 0:51ac1d130fd4 16 * 2. Redistributions in binary form must reproduce the above copyright notice,
mbed_official 0:51ac1d130fd4 17 * this list of conditions and the following disclaimer in the documentation
mbed_official 0:51ac1d130fd4 18 * and/or other materials provided with the distribution.
mbed_official 0:51ac1d130fd4 19 * 3. The name of the author may not be used to endorse or promote products
mbed_official 0:51ac1d130fd4 20 * derived from this software without specific prior written permission.
mbed_official 0:51ac1d130fd4 21 *
mbed_official 0:51ac1d130fd4 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
mbed_official 0:51ac1d130fd4 23 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
mbed_official 0:51ac1d130fd4 24 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
mbed_official 0:51ac1d130fd4 25 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
mbed_official 0:51ac1d130fd4 26 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
mbed_official 0:51ac1d130fd4 27 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
mbed_official 0:51ac1d130fd4 28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
mbed_official 0:51ac1d130fd4 29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
mbed_official 0:51ac1d130fd4 30 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
mbed_official 0:51ac1d130fd4 31 * OF SUCH DAMAGE.
mbed_official 0:51ac1d130fd4 32 *
mbed_official 0:51ac1d130fd4 33 * This file is part of the lwIP TCP/IP stack.
mbed_official 0:51ac1d130fd4 34 *
mbed_official 0:51ac1d130fd4 35 * Author: Adam Dunkels <adam@sics.se>
mbed_official 0:51ac1d130fd4 36 *
mbed_official 0:51ac1d130fd4 37 */
mbed_official 0:51ac1d130fd4 38
mbed_official 0:51ac1d130fd4 39 /* Some ICMP messages should be passed to the transport protocols. This
mbed_official 0:51ac1d130fd4 40 is not implemented. */
mbed_official 0:51ac1d130fd4 41
mbed_official 0:51ac1d130fd4 42 #include "lwip/opt.h"
mbed_official 0:51ac1d130fd4 43
mbed_official 0:51ac1d130fd4 44 #if LWIP_ICMP /* don't build if not configured for use in lwipopts.h */
mbed_official 0:51ac1d130fd4 45
mbed_official 0:51ac1d130fd4 46 #include "lwip/icmp.h"
mbed_official 0:51ac1d130fd4 47 #include "lwip/inet_chksum.h"
mbed_official 0:51ac1d130fd4 48 #include "lwip/ip.h"
mbed_official 0:51ac1d130fd4 49 #include "lwip/def.h"
mbed_official 0:51ac1d130fd4 50 #include "lwip/stats.h"
mbed_official 0:51ac1d130fd4 51 #include "lwip/snmp.h"
mbed_official 0:51ac1d130fd4 52
mbed_official 0:51ac1d130fd4 53 #include <string.h>
mbed_official 0:51ac1d130fd4 54
mbed_official 0:51ac1d130fd4 55 /** Small optimization: set to 0 if incoming PBUF_POOL pbuf always can be
mbed_official 0:51ac1d130fd4 56 * used to modify and send a response packet (and to 1 if this is not the case,
mbed_official 0:51ac1d130fd4 57 * e.g. when link header is stripped of when receiving) */
mbed_official 0:51ac1d130fd4 58 #ifndef LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
mbed_official 0:51ac1d130fd4 59 #define LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN 1
mbed_official 0:51ac1d130fd4 60 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
mbed_official 0:51ac1d130fd4 61
mbed_official 0:51ac1d130fd4 62 /* The amount of data from the original packet to return in a dest-unreachable */
mbed_official 0:51ac1d130fd4 63 #define ICMP_DEST_UNREACH_DATASIZE 8
mbed_official 0:51ac1d130fd4 64
mbed_official 0:51ac1d130fd4 65 static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code);
mbed_official 0:51ac1d130fd4 66
mbed_official 0:51ac1d130fd4 67 /**
mbed_official 0:51ac1d130fd4 68 * Processes ICMP input packets, called from ip_input().
mbed_official 0:51ac1d130fd4 69 *
mbed_official 0:51ac1d130fd4 70 * Currently only processes icmp echo requests and sends
mbed_official 0:51ac1d130fd4 71 * out the echo response.
mbed_official 0:51ac1d130fd4 72 *
mbed_official 0:51ac1d130fd4 73 * @param p the icmp echo request packet, p->payload pointing to the ip header
mbed_official 0:51ac1d130fd4 74 * @param inp the netif on which this packet was received
mbed_official 0:51ac1d130fd4 75 */
mbed_official 0:51ac1d130fd4 76 void
mbed_official 0:51ac1d130fd4 77 icmp_input(struct pbuf *p, struct netif *inp)
mbed_official 0:51ac1d130fd4 78 {
mbed_official 0:51ac1d130fd4 79 u8_t type;
mbed_official 0:51ac1d130fd4 80 #ifdef LWIP_DEBUG
mbed_official 0:51ac1d130fd4 81 u8_t code;
mbed_official 0:51ac1d130fd4 82 #endif /* LWIP_DEBUG */
mbed_official 0:51ac1d130fd4 83 struct icmp_echo_hdr *iecho;
mbed_official 0:51ac1d130fd4 84 struct ip_hdr *iphdr;
mbed_official 0:51ac1d130fd4 85 s16_t hlen;
mbed_official 0:51ac1d130fd4 86
mbed_official 0:51ac1d130fd4 87 ICMP_STATS_INC(icmp.recv);
mbed_official 0:51ac1d130fd4 88 snmp_inc_icmpinmsgs();
mbed_official 0:51ac1d130fd4 89
mbed_official 0:51ac1d130fd4 90
mbed_official 0:51ac1d130fd4 91 iphdr = (struct ip_hdr *)p->payload;
mbed_official 0:51ac1d130fd4 92 hlen = IPH_HL(iphdr) * 4;
mbed_official 0:51ac1d130fd4 93 if (pbuf_header(p, -hlen) || (p->tot_len < sizeof(u16_t)*2)) {
mbed_official 0:51ac1d130fd4 94 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
mbed_official 0:51ac1d130fd4 95 goto lenerr;
mbed_official 0:51ac1d130fd4 96 }
mbed_official 0:51ac1d130fd4 97
mbed_official 0:51ac1d130fd4 98 type = *((u8_t *)p->payload);
mbed_official 0:51ac1d130fd4 99 #ifdef LWIP_DEBUG
mbed_official 0:51ac1d130fd4 100 code = *(((u8_t *)p->payload)+1);
mbed_official 0:51ac1d130fd4 101 #endif /* LWIP_DEBUG */
mbed_official 0:51ac1d130fd4 102 switch (type) {
mbed_official 0:51ac1d130fd4 103 case ICMP_ER:
mbed_official 0:51ac1d130fd4 104 /* This is OK, echo reply might have been parsed by a raw PCB
mbed_official 0:51ac1d130fd4 105 (as obviously, an echo request has been sent, too). */
mbed_official 0:51ac1d130fd4 106 break;
mbed_official 0:51ac1d130fd4 107 case ICMP_ECHO:
mbed_official 0:51ac1d130fd4 108 #if !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
mbed_official 0:51ac1d130fd4 109 {
mbed_official 0:51ac1d130fd4 110 int accepted = 1;
mbed_official 0:51ac1d130fd4 111 #if !LWIP_MULTICAST_PING
mbed_official 0:51ac1d130fd4 112 /* multicast destination address? */
mbed_official 0:51ac1d130fd4 113 if (ip_addr_ismulticast(&current_iphdr_dest)) {
mbed_official 0:51ac1d130fd4 114 accepted = 0;
mbed_official 0:51ac1d130fd4 115 }
mbed_official 0:51ac1d130fd4 116 #endif /* LWIP_MULTICAST_PING */
mbed_official 0:51ac1d130fd4 117 #if !LWIP_BROADCAST_PING
mbed_official 0:51ac1d130fd4 118 /* broadcast destination address? */
mbed_official 0:51ac1d130fd4 119 if (ip_addr_isbroadcast(&current_iphdr_dest, inp)) {
mbed_official 0:51ac1d130fd4 120 accepted = 0;
mbed_official 0:51ac1d130fd4 121 }
mbed_official 0:51ac1d130fd4 122 #endif /* LWIP_BROADCAST_PING */
mbed_official 0:51ac1d130fd4 123 /* broadcast or multicast destination address not acceptd? */
mbed_official 0:51ac1d130fd4 124 if (!accepted) {
mbed_official 0:51ac1d130fd4 125 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
mbed_official 0:51ac1d130fd4 126 ICMP_STATS_INC(icmp.err);
mbed_official 0:51ac1d130fd4 127 pbuf_free(p);
mbed_official 0:51ac1d130fd4 128 return;
mbed_official 0:51ac1d130fd4 129 }
mbed_official 0:51ac1d130fd4 130 }
mbed_official 0:51ac1d130fd4 131 #endif /* !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
mbed_official 0:51ac1d130fd4 132 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
mbed_official 0:51ac1d130fd4 133 if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
mbed_official 0:51ac1d130fd4 134 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
mbed_official 0:51ac1d130fd4 135 goto lenerr;
mbed_official 0:51ac1d130fd4 136 }
mbed_official 0:51ac1d130fd4 137 if (inet_chksum_pbuf(p) != 0) {
mbed_official 0:51ac1d130fd4 138 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
mbed_official 0:51ac1d130fd4 139 pbuf_free(p);
mbed_official 0:51ac1d130fd4 140 ICMP_STATS_INC(icmp.chkerr);
mbed_official 0:51ac1d130fd4 141 snmp_inc_icmpinerrors();
mbed_official 0:51ac1d130fd4 142 return;
mbed_official 0:51ac1d130fd4 143 }
mbed_official 0:51ac1d130fd4 144 #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
mbed_official 0:51ac1d130fd4 145 if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
mbed_official 0:51ac1d130fd4 146 /* p is not big enough to contain link headers
mbed_official 0:51ac1d130fd4 147 * allocate a new one and copy p into it
mbed_official 0:51ac1d130fd4 148 */
mbed_official 0:51ac1d130fd4 149 struct pbuf *r;
mbed_official 0:51ac1d130fd4 150 /* switch p->payload to ip header */
mbed_official 0:51ac1d130fd4 151 if (pbuf_header(p, hlen)) {
mbed_official 0:51ac1d130fd4 152 LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
mbed_official 0:51ac1d130fd4 153 goto memerr;
mbed_official 0:51ac1d130fd4 154 }
mbed_official 0:51ac1d130fd4 155 /* allocate new packet buffer with space for link headers */
mbed_official 0:51ac1d130fd4 156 r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
mbed_official 0:51ac1d130fd4 157 if (r == NULL) {
mbed_official 0:51ac1d130fd4 158 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
mbed_official 0:51ac1d130fd4 159 goto memerr;
mbed_official 0:51ac1d130fd4 160 }
mbed_official 0:51ac1d130fd4 161 LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
mbed_official 0:51ac1d130fd4 162 (r->len >= hlen + sizeof(struct icmp_echo_hdr)));
mbed_official 0:51ac1d130fd4 163 /* copy the whole packet including ip header */
mbed_official 0:51ac1d130fd4 164 if (pbuf_copy(r, p) != ERR_OK) {
mbed_official 0:51ac1d130fd4 165 LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
mbed_official 0:51ac1d130fd4 166 goto memerr;
mbed_official 0:51ac1d130fd4 167 }
mbed_official 0:51ac1d130fd4 168 iphdr = (struct ip_hdr *)r->payload;
mbed_official 0:51ac1d130fd4 169 /* switch r->payload back to icmp header */
mbed_official 0:51ac1d130fd4 170 if (pbuf_header(r, -hlen)) {
mbed_official 0:51ac1d130fd4 171 LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
mbed_official 0:51ac1d130fd4 172 goto memerr;
mbed_official 0:51ac1d130fd4 173 }
mbed_official 0:51ac1d130fd4 174 /* free the original p */
mbed_official 0:51ac1d130fd4 175 pbuf_free(p);
mbed_official 0:51ac1d130fd4 176 /* we now have an identical copy of p that has room for link headers */
mbed_official 0:51ac1d130fd4 177 p = r;
mbed_official 0:51ac1d130fd4 178 } else {
mbed_official 0:51ac1d130fd4 179 /* restore p->payload to point to icmp header */
mbed_official 0:51ac1d130fd4 180 if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
mbed_official 0:51ac1d130fd4 181 LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
mbed_official 0:51ac1d130fd4 182 goto memerr;
mbed_official 0:51ac1d130fd4 183 }
mbed_official 0:51ac1d130fd4 184 }
mbed_official 0:51ac1d130fd4 185 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
mbed_official 0:51ac1d130fd4 186 /* At this point, all checks are OK. */
mbed_official 0:51ac1d130fd4 187 /* We generate an answer by switching the dest and src ip addresses,
mbed_official 0:51ac1d130fd4 188 * setting the icmp type to ECHO_RESPONSE and updating the checksum. */
mbed_official 0:51ac1d130fd4 189 iecho = (struct icmp_echo_hdr *)p->payload;
mbed_official 0:51ac1d130fd4 190 ip_addr_copy(iphdr->src, *ip_current_dest_addr());
mbed_official 0:51ac1d130fd4 191 ip_addr_copy(iphdr->dest, *ip_current_src_addr());
mbed_official 0:51ac1d130fd4 192 ICMPH_TYPE_SET(iecho, ICMP_ER);
mbed_official 0:51ac1d130fd4 193 /* adjust the checksum */
mbed_official 0:51ac1d130fd4 194 if (iecho->chksum >= PP_HTONS(0xffffU - (ICMP_ECHO << 8))) {
mbed_official 0:51ac1d130fd4 195 iecho->chksum += PP_HTONS(ICMP_ECHO << 8) + 1;
mbed_official 0:51ac1d130fd4 196 } else {
mbed_official 0:51ac1d130fd4 197 iecho->chksum += PP_HTONS(ICMP_ECHO << 8);
mbed_official 0:51ac1d130fd4 198 }
mbed_official 0:51ac1d130fd4 199
mbed_official 0:51ac1d130fd4 200 /* Set the correct TTL and recalculate the header checksum. */
mbed_official 0:51ac1d130fd4 201 IPH_TTL_SET(iphdr, ICMP_TTL);
mbed_official 0:51ac1d130fd4 202 IPH_CHKSUM_SET(iphdr, 0);
mbed_official 0:51ac1d130fd4 203 #if CHECKSUM_GEN_IP
mbed_official 0:51ac1d130fd4 204 IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
mbed_official 0:51ac1d130fd4 205 #endif /* CHECKSUM_GEN_IP */
mbed_official 0:51ac1d130fd4 206
mbed_official 0:51ac1d130fd4 207 ICMP_STATS_INC(icmp.xmit);
mbed_official 0:51ac1d130fd4 208 /* increase number of messages attempted to send */
mbed_official 0:51ac1d130fd4 209 snmp_inc_icmpoutmsgs();
mbed_official 0:51ac1d130fd4 210 /* increase number of echo replies attempted to send */
mbed_official 0:51ac1d130fd4 211 snmp_inc_icmpoutechoreps();
mbed_official 0:51ac1d130fd4 212
mbed_official 0:51ac1d130fd4 213 if(pbuf_header(p, hlen)) {
mbed_official 0:51ac1d130fd4 214 LWIP_ASSERT("Can't move over header in packet", 0);
mbed_official 0:51ac1d130fd4 215 } else {
mbed_official 0:51ac1d130fd4 216 err_t ret;
mbed_official 0:51ac1d130fd4 217 /* send an ICMP packet, src addr is the dest addr of the curren packet */
mbed_official 0:51ac1d130fd4 218 ret = ip_output_if(p, ip_current_dest_addr(), IP_HDRINCL,
mbed_official 0:51ac1d130fd4 219 ICMP_TTL, 0, IP_PROTO_ICMP, inp);
mbed_official 0:51ac1d130fd4 220 if (ret != ERR_OK) {
mbed_official 0:51ac1d130fd4 221 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
mbed_official 0:51ac1d130fd4 222 }
mbed_official 0:51ac1d130fd4 223 }
mbed_official 0:51ac1d130fd4 224 break;
mbed_official 0:51ac1d130fd4 225 default:
mbed_official 0:51ac1d130fd4 226 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
mbed_official 0:51ac1d130fd4 227 (s16_t)type, (s16_t)code));
mbed_official 0:51ac1d130fd4 228 ICMP_STATS_INC(icmp.proterr);
mbed_official 0:51ac1d130fd4 229 ICMP_STATS_INC(icmp.drop);
mbed_official 0:51ac1d130fd4 230 }
mbed_official 0:51ac1d130fd4 231 pbuf_free(p);
mbed_official 0:51ac1d130fd4 232 return;
mbed_official 0:51ac1d130fd4 233 lenerr:
mbed_official 0:51ac1d130fd4 234 pbuf_free(p);
mbed_official 0:51ac1d130fd4 235 ICMP_STATS_INC(icmp.lenerr);
mbed_official 0:51ac1d130fd4 236 snmp_inc_icmpinerrors();
mbed_official 0:51ac1d130fd4 237 return;
mbed_official 0:51ac1d130fd4 238 #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
mbed_official 0:51ac1d130fd4 239 memerr:
mbed_official 0:51ac1d130fd4 240 pbuf_free(p);
mbed_official 0:51ac1d130fd4 241 ICMP_STATS_INC(icmp.err);
mbed_official 0:51ac1d130fd4 242 snmp_inc_icmpinerrors();
mbed_official 0:51ac1d130fd4 243 return;
mbed_official 0:51ac1d130fd4 244 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
mbed_official 0:51ac1d130fd4 245 }
mbed_official 0:51ac1d130fd4 246
mbed_official 0:51ac1d130fd4 247 /**
mbed_official 0:51ac1d130fd4 248 * Send an icmp 'destination unreachable' packet, called from ip_input() if
mbed_official 0:51ac1d130fd4 249 * the transport layer protocol is unknown and from udp_input() if the local
mbed_official 0:51ac1d130fd4 250 * port is not bound.
mbed_official 0:51ac1d130fd4 251 *
mbed_official 0:51ac1d130fd4 252 * @param p the input packet for which the 'unreachable' should be sent,
mbed_official 0:51ac1d130fd4 253 * p->payload pointing to the IP header
mbed_official 0:51ac1d130fd4 254 * @param t type of the 'unreachable' packet
mbed_official 0:51ac1d130fd4 255 */
mbed_official 0:51ac1d130fd4 256 void
mbed_official 0:51ac1d130fd4 257 icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t)
mbed_official 0:51ac1d130fd4 258 {
mbed_official 0:51ac1d130fd4 259 icmp_send_response(p, ICMP_DUR, t);
mbed_official 0:51ac1d130fd4 260 }
mbed_official 0:51ac1d130fd4 261
mbed_official 0:51ac1d130fd4 262 #if IP_FORWARD || IP_REASSEMBLY
mbed_official 0:51ac1d130fd4 263 /**
mbed_official 0:51ac1d130fd4 264 * Send a 'time exceeded' packet, called from ip_forward() if TTL is 0.
mbed_official 0:51ac1d130fd4 265 *
mbed_official 0:51ac1d130fd4 266 * @param p the input packet for which the 'time exceeded' should be sent,
mbed_official 0:51ac1d130fd4 267 * p->payload pointing to the IP header
mbed_official 0:51ac1d130fd4 268 * @param t type of the 'time exceeded' packet
mbed_official 0:51ac1d130fd4 269 */
mbed_official 0:51ac1d130fd4 270 void
mbed_official 0:51ac1d130fd4 271 icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t)
mbed_official 0:51ac1d130fd4 272 {
mbed_official 0:51ac1d130fd4 273 icmp_send_response(p, ICMP_TE, t);
mbed_official 0:51ac1d130fd4 274 }
mbed_official 0:51ac1d130fd4 275
mbed_official 0:51ac1d130fd4 276 #endif /* IP_FORWARD || IP_REASSEMBLY */
mbed_official 0:51ac1d130fd4 277
mbed_official 0:51ac1d130fd4 278 /**
mbed_official 0:51ac1d130fd4 279 * Send an icmp packet in response to an incoming packet.
mbed_official 0:51ac1d130fd4 280 *
mbed_official 0:51ac1d130fd4 281 * @param p the input packet for which the 'unreachable' should be sent,
mbed_official 0:51ac1d130fd4 282 * p->payload pointing to the IP header
mbed_official 0:51ac1d130fd4 283 * @param type Type of the ICMP header
mbed_official 0:51ac1d130fd4 284 * @param code Code of the ICMP header
mbed_official 0:51ac1d130fd4 285 */
mbed_official 0:51ac1d130fd4 286 static void
mbed_official 0:51ac1d130fd4 287 icmp_send_response(struct pbuf *p, u8_t type, u8_t code)
mbed_official 0:51ac1d130fd4 288 {
mbed_official 0:51ac1d130fd4 289 struct pbuf *q;
mbed_official 0:51ac1d130fd4 290 struct ip_hdr *iphdr;
mbed_official 0:51ac1d130fd4 291 /* we can use the echo header here */
mbed_official 0:51ac1d130fd4 292 struct icmp_echo_hdr *icmphdr;
mbed_official 0:51ac1d130fd4 293 ip_addr_t iphdr_src;
mbed_official 0:51ac1d130fd4 294
mbed_official 0:51ac1d130fd4 295 /* ICMP header + IP header + 8 bytes of data */
mbed_official 0:51ac1d130fd4 296 q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE,
mbed_official 0:51ac1d130fd4 297 PBUF_RAM);
mbed_official 0:51ac1d130fd4 298 if (q == NULL) {
mbed_official 0:51ac1d130fd4 299 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n"));
mbed_official 0:51ac1d130fd4 300 return;
mbed_official 0:51ac1d130fd4 301 }
mbed_official 0:51ac1d130fd4 302 LWIP_ASSERT("check that first pbuf can hold icmp message",
mbed_official 0:51ac1d130fd4 303 (q->len >= (sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE)));
mbed_official 0:51ac1d130fd4 304
mbed_official 0:51ac1d130fd4 305 iphdr = (struct ip_hdr *)p->payload;
mbed_official 0:51ac1d130fd4 306 LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));
mbed_official 0:51ac1d130fd4 307 ip_addr_debug_print(ICMP_DEBUG, &(iphdr->src));
mbed_official 0:51ac1d130fd4 308 LWIP_DEBUGF(ICMP_DEBUG, (" to "));
mbed_official 0:51ac1d130fd4 309 ip_addr_debug_print(ICMP_DEBUG, &(iphdr->dest));
mbed_official 0:51ac1d130fd4 310 LWIP_DEBUGF(ICMP_DEBUG, ("\n"));
mbed_official 0:51ac1d130fd4 311
mbed_official 0:51ac1d130fd4 312 icmphdr = (struct icmp_echo_hdr *)q->payload;
mbed_official 0:51ac1d130fd4 313 icmphdr->type = type;
mbed_official 0:51ac1d130fd4 314 icmphdr->code = code;
mbed_official 0:51ac1d130fd4 315 icmphdr->id = 0;
mbed_official 0:51ac1d130fd4 316 icmphdr->seqno = 0;
mbed_official 0:51ac1d130fd4 317
mbed_official 0:51ac1d130fd4 318 /* copy fields from original packet */
mbed_official 0:51ac1d130fd4 319 SMEMCPY((u8_t *)q->payload + sizeof(struct icmp_echo_hdr), (u8_t *)p->payload,
mbed_official 0:51ac1d130fd4 320 IP_HLEN + ICMP_DEST_UNREACH_DATASIZE);
mbed_official 0:51ac1d130fd4 321
mbed_official 0:51ac1d130fd4 322 /* calculate checksum */
mbed_official 0:51ac1d130fd4 323 icmphdr->chksum = 0;
mbed_official 0:51ac1d130fd4 324 icmphdr->chksum = inet_chksum(icmphdr, q->len);
mbed_official 0:51ac1d130fd4 325 ICMP_STATS_INC(icmp.xmit);
mbed_official 0:51ac1d130fd4 326 /* increase number of messages attempted to send */
mbed_official 0:51ac1d130fd4 327 snmp_inc_icmpoutmsgs();
mbed_official 0:51ac1d130fd4 328 /* increase number of destination unreachable messages attempted to send */
mbed_official 0:51ac1d130fd4 329 snmp_inc_icmpouttimeexcds();
mbed_official 0:51ac1d130fd4 330 ip_addr_copy(iphdr_src, iphdr->src);
mbed_official 0:51ac1d130fd4 331 ip_output(q, NULL, &iphdr_src, ICMP_TTL, 0, IP_PROTO_ICMP);
mbed_official 0:51ac1d130fd4 332 pbuf_free(q);
mbed_official 0:51ac1d130fd4 333 }
mbed_official 0:51ac1d130fd4 334
mbed_official 0:51ac1d130fd4 335 #endif /* LWIP_ICMP */