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