lib/drivers/lwip/src/core/ipv4/icmp.c

   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_ICMP /* don't build if not configured for use in lwipopts.h */
  45
  46 #include "lwip/icmp.h"
  47 #include "lwip/inet.h"
  48 #include "lwip/inet_chksum.h"
  49 #include "lwip/ip.h"
  50 #include "lwip/def.h"
  51 #include "lwip/stats.h"
  52 #include "lwip/snmp.h"
  53
  54 #include <string.h>
  55
  56 /** Small optimization: set to 0 if incoming PBUF_POOL pbuf always can be
  57  * used to modify and send a response packet (and to 1 if this is not the case,
  58  * e.g. when link header is stripped of when receiving) */
  59 #ifndef LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
  60 #define LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN 1
  61 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
  62
  63 /* The amount of data from the original packet to return in a dest-unreachable */
  64 #define ICMP_DEST_UNREACH_DATASIZE 8
  65
  66 static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code);
  67
  68 /**
  69  * Processes ICMP input packets, called from ip_input().
  70  *
  71  * Currently only processes icmp echo requests and sends
  72  * out the echo response.
  73  *
  74  * @param p the icmp echo request packet, p->payload pointing to the ip header
  75  * @param inp the netif on which this packet was received
  76  */
  77 void
  78 icmp_input(struct pbuf *p, struct netif *inp)
  79 {
  80   u8_t type;
  81 #ifdef LWIP_DEBUG
  82   u8_t code;
  83 #endif /* LWIP_DEBUG */
  84   struct icmp_echo_hdr *iecho;
  85   struct ip_hdr *iphdr;
  86   struct ip_addr tmpaddr;
  87   s16_t hlen;
  88
  89   ICMP_STATS_INC(icmp.recv);
  90   snmp_inc_icmpinmsgs();
  91
  92
  93   iphdr = p->payload;
  94   hlen = IPH_HL(iphdr) * 4;
  95   if (pbuf_header(p, -hlen) || (p->tot_len < sizeof(u16_t)*2)) {
  96     LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
  97     goto lenerr;
  98   }
  99
 100   type = *((u8_t *)p->payload);
 101 #ifdef LWIP_DEBUG
 102   code = *(((u8_t *)p->payload)+1);
 103 #endif /* LWIP_DEBUG */
 104   switch (type) {
 105   case ICMP_ECHO:
 106 #if !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
 107     {
 108       int accepted = 1;
 109 #if !LWIP_MULTICAST_PING
 110       /* multicast destination address? */
 111       if (ip_addr_ismulticast(&iphdr->dest)) {
 112         accepted = 0;
 113       }
 114 #endif /* LWIP_MULTICAST_PING */
 115 #if !LWIP_BROADCAST_PING
 116       /* broadcast destination address? */
 117       if (ip_addr_isbroadcast(&iphdr->dest, inp)) {
 118         accepted = 0;
 119       }
 120 #endif /* LWIP_BROADCAST_PING */
 121       /* broadcast or multicast destination address not acceptd? */
 122       if (!accepted) {
 123         LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
 124         ICMP_STATS_INC(icmp.err);
 125         pbuf_free(p);
 126         return;
 127       }
 128     }
 129 #endif /* !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
 130     LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
 131     if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
 132       LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
 133       goto lenerr;
 134     }
 135     if (inet_chksum_pbuf(p) != 0) {
 136       LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
 137       pbuf_free(p);
 138       ICMP_STATS_INC(icmp.chkerr);
 139       snmp_inc_icmpinerrors();
 140       return;
 141     }
 142 #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
 143     if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
 144       /* p is not big enough to contain link headers
 145        * allocate a new one and copy p into it
 146        */
 147       struct pbuf *r;
 148       /* switch p->payload to ip header */
 149       if (pbuf_header(p, hlen)) {
 150         LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
 151         goto memerr;
 152       }
 153       /* allocate new packet buffer with space for link headers */
 154       r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
 155       if (r == NULL) {
 156         LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
 157         goto memerr;
 158       }
 159       LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
 160                   (r->len >= hlen + sizeof(struct icmp_echo_hdr)));
 161       /* copy the whole packet including ip header */
 162       if (pbuf_copy(r, p) != ERR_OK) {
 163         LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
 164         goto memerr;
 165       }
 166       iphdr = r->payload;
 167       /* switch r->payload back to icmp header */
 168       if (pbuf_header(r, -hlen)) {
 169         LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
 170         goto memerr;
 171       }
 172       /* free the original p */
 173       pbuf_free(p);
 174       /* we now have an identical copy of p that has room for link headers */
 175       p = r;
 176     } else {
 177       /* restore p->payload to point to icmp header */
 178       if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
 179         LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
 180         goto memerr;
 181       }
 182     }
 183 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
 184     /* At this point, all checks are OK. */
 185     /* We generate an answer by switching the dest and src ip addresses,
 186      * setting the icmp type to ECHO_RESPONSE and updating the checksum. */
 187     iecho = p->payload;
 188     tmpaddr.addr = iphdr->src.addr;
 189     iphdr->src.addr = iphdr->dest.addr;
 190     iphdr->dest.addr = tmpaddr.addr;
 191     ICMPH_TYPE_SET(iecho, ICMP_ER);
 192     /* adjust the checksum */
 193     if (iecho->chksum >= htons(0xffff - (ICMP_ECHO << 8))) {
 194       iecho->chksum += htons(ICMP_ECHO << 8) + 1;
 195     } else {
 196       iecho->chksum += htons(ICMP_ECHO << 8);
 197     }
 198
 199     /* Set the correct TTL and recalculate the header checksum. */
 200     IPH_TTL_SET(iphdr, ICMP_TTL);
 201     IPH_CHKSUM_SET(iphdr, 0);
 202 #if CHECKSUM_GEN_IP
 203     IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
 204 #endif /* CHECKSUM_GEN_IP */
 205
 206     ICMP_STATS_INC(icmp.xmit);
 207     /* increase number of messages attempted to send */
 208     snmp_inc_icmpoutmsgs();
 209     /* increase number of echo replies attempted to send */
 210     snmp_inc_icmpoutechoreps();
 211
 212     if(pbuf_header(p, hlen)) {
 213       LWIP_ASSERT("Can't move over header in packet", 0);
 214     } else {
 215       err_t ret;
 216       ret = ip_output_if(p, &(iphdr->src), IP_HDRINCL,
 217                    ICMP_TTL, 0, IP_PROTO_ICMP, inp);
 218       if (ret != ERR_OK) {
 219         LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
 220       }
 221     }
 222     break;
 223   default:
 224     LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
 225                 (s16_t)type, (s16_t)code));
 226     ICMP_STATS_INC(icmp.proterr);
 227     ICMP_STATS_INC(icmp.drop);
 228   }
 229   pbuf_free(p);
 230   return;
 231 lenerr:
 232   pbuf_free(p);
 233   ICMP_STATS_INC(icmp.lenerr);
 234   snmp_inc_icmpinerrors();
 235   return;
 236 #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
 237 memerr:
 238   pbuf_free(p);
 239   ICMP_STATS_INC(icmp.err);
 240   snmp_inc_icmpinerrors();
 241   return;
 242 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
 243 }
 244
 245 /**
 246  * Send an icmp 'destination unreachable' packet, called from ip_input() if
 247  * the transport layer protocol is unknown and from udp_input() if the local
 248  * port is not bound.
 249  *
 250  * @param p the input packet for which the 'unreachable' should be sent,
 251  *          p->payload pointing to the IP header
 252  * @param t type of the 'unreachable' packet
 253  */
 254 void
 255 icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t)
 256 {
 257   icmp_send_response(p, ICMP_DUR, t);
 258 }
 259
 260 #if IP_FORWARD || IP_REASSEMBLY
 261 /**
 262  * Send a 'time exceeded' packet, called from ip_forward() if TTL is 0.
 263  *
 264  * @param p the input packet for which the 'time exceeded' should be sent,
 265  *          p->payload pointing to the IP header
 266  * @param t type of the 'time exceeded' packet
 267  */
 268 void
 269 icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t)
 270 {
 271   icmp_send_response(p, ICMP_TE, t);
 272 }
 273
 274 #endif /* IP_FORWARD || IP_REASSEMBLY */
 275
 276 /**
 277  * Send an icmp packet in response to an incoming packet.
 278  *
 279  * @param p the input packet for which the 'unreachable' should be sent,
 280  *          p->payload pointing to the IP header
 281  * @param type Type of the ICMP header
 282  * @param code Code of the ICMP header
 283  */
 284 static void
 285 icmp_send_response(struct pbuf *p, u8_t type, u8_t code)
 286 {
 287   struct pbuf *q;
 288   struct ip_hdr *iphdr;
 289   /* we can use the echo header here */
 290   struct icmp_echo_hdr *icmphdr;
 291
 292   /* ICMP header + IP header + 8 bytes of data */
 293   q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE,
 294                  PBUF_RAM);
 295   if (q == NULL) {
 296     LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n"));
 297     return;
 298   }
 299   LWIP_ASSERT("check that first pbuf can hold icmp message",
 300              (q->len >= (sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE)));
 301
 302   iphdr = p->payload;
 303   LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));
 304   ip_addr_debug_print(ICMP_DEBUG, &(iphdr->src));
 305   LWIP_DEBUGF(ICMP_DEBUG, (" to "));
 306   ip_addr_debug_print(ICMP_DEBUG, &(iphdr->dest));
 307   LWIP_DEBUGF(ICMP_DEBUG, ("\n"));
 308
 309   icmphdr = q->payload;
 310   icmphdr->type = type;
 311   icmphdr->code = code;
 312   icmphdr->id = 0;
 313   icmphdr->seqno = 0;
 314
 315   /* copy fields from original packet */
 316   SMEMCPY((u8_t *)q->payload + sizeof(struct icmp_echo_hdr), (u8_t *)p->payload,
 317           IP_HLEN + ICMP_DEST_UNREACH_DATASIZE);
 318
 319   /* calculate checksum */
 320   icmphdr->chksum = 0;
 321   icmphdr->chksum = inet_chksum(icmphdr, q->len);
 322   ICMP_STATS_INC(icmp.xmit);
 323   /* increase number of messages attempted to send */
 324   snmp_inc_icmpoutmsgs();
 325   /* increase number of destination unreachable messages attempted to send */
 326   snmp_inc_icmpouttimeexcds();
 327   ip_output(q, NULL, &(iphdr->src), ICMP_TTL, 0, IP_PROTO_ICMP);
 328   pbuf_free(q);
 329 }
 330
 331 #endif /* LWIP_ICMP */