reactos/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_chksum.h"
  48 #include "lwip/ip.h"
  49 #include "lwip/def.h"
  50 #include "lwip/stats.h"
  51 #include "lwip/snmp.h"
  52
  53 #include <string.h>
  54
  55 /** Small optimization: set to 0 if incoming PBUF_POOL pbuf always can be
  56  * used to modify and send a response packet (and to 1 if this is not the case,
  57  * e.g. when link header is stripped of when receiving) */
  58 #ifndef LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
  59 #define LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN 1
  60 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
  61
  62 /* The amount of data from the original packet to return in a dest-unreachable */
  63 #define ICMP_DEST_UNREACH_DATASIZE 8
  64
  65 static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code);
  66
  67 /**
  68  * Processes ICMP input packets, called from ip_input().
  69  *
  70  * Currently only processes icmp echo requests and sends
  71  * out the echo response.
  72  *
  73  * @param p the icmp echo request packet, p->payload pointing to the ip header
  74  * @param inp the netif on which this packet was received
  75  */
  76 void
  77 icmp_input(struct pbuf *p, struct netif *inp)
  78 {
  79   u8_t type;
  80 #ifdef LWIP_DEBUG
  81   u8_t code;
  82 #endif /* LWIP_DEBUG */
  83   struct icmp_echo_hdr *iecho;
  84   struct ip_hdr *iphdr;
  85   s16_t hlen;
  86
  87   ICMP_STATS_INC(icmp.recv);
  88   snmp_inc_icmpinmsgs();
  89
  90
  91   iphdr = (struct ip_hdr *)p->payload;
  92   hlen = IPH_HL(iphdr) * 4;
  93   if (pbuf_header(p, -hlen) || (p->tot_len < sizeof(u16_t)*2)) {
  94     LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
  95     goto lenerr;
  96   }
  97
  98   type = *((u8_t *)p->payload);
  99 #ifdef LWIP_DEBUG
 100   code = *(((u8_t *)p->payload)+1);
 101 #endif /* LWIP_DEBUG */
 102   switch (type) {
 103   case ICMP_ER:
 104     /* This is OK, echo reply might have been parsed by a raw PCB
 105        (as obviously, an echo request has been sent, too). */
 106     break;
 107   case ICMP_ECHO:
 108 #if !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
 109     {
 110       int accepted = 1;
 111 #if !LWIP_MULTICAST_PING
 112       /* multicast destination address? */
 113       if (ip_addr_ismulticast(&current_iphdr_dest)) {
 114         accepted = 0;
 115       }
 116 #endif /* LWIP_MULTICAST_PING */
 117 #if !LWIP_BROADCAST_PING
 118       /* broadcast destination address? */
 119       if (ip_addr_isbroadcast(&current_iphdr_dest, inp)) {
 120         accepted = 0;
 121       }
 122 #endif /* LWIP_BROADCAST_PING */
 123       /* broadcast or multicast destination address not acceptd? */
 124       if (!accepted) {
 125         LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
 126         ICMP_STATS_INC(icmp.err);
 127         pbuf_free(p);
 128         return;
 129       }
 130     }
 131 #endif /* !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
 132     LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
 133     if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
 134       LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
 135       goto lenerr;
 136     }
 137     if (inet_chksum_pbuf(p) != 0) {
 138       LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
 139       pbuf_free(p);
 140       ICMP_STATS_INC(icmp.chkerr);
 141       snmp_inc_icmpinerrors();
 142       return;
 143     }
 144 #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
 145     if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
 146       /* p is not big enough to contain link headers
 147        * allocate a new one and copy p into it
 148        */
 149       struct pbuf *r;
 150       /* switch p->payload to ip header */
 151       if (pbuf_header(p, hlen)) {
 152         LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
 153         goto memerr;
 154       }
 155       /* allocate new packet buffer with space for link headers */
 156       r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
 157       if (r == NULL) {
 158         LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
 159         goto memerr;
 160       }
 161       LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
 162                   (r->len >= hlen + sizeof(struct icmp_echo_hdr)));
 163       /* copy the whole packet including ip header */
 164       if (pbuf_copy(r, p) != ERR_OK) {
 165         LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
 166         goto memerr;
 167       }
 168       iphdr = (struct ip_hdr *)r->payload;
 169       /* switch r->payload back to icmp header */
 170       if (pbuf_header(r, -hlen)) {
 171         LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
 172         goto memerr;
 173       }
 174       /* free the original p */
 175       pbuf_free(p);
 176       /* we now have an identical copy of p that has room for link headers */
 177       p = r;
 178     } else {
 179       /* restore p->payload to point to icmp header */
 180       if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
 181         LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
 182         goto memerr;
 183       }
 184     }
 185 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
 186     /* At this point, all checks are OK. */
 187     /* We generate an answer by switching the dest and src ip addresses,
 188      * setting the icmp type to ECHO_RESPONSE and updating the checksum. */
 189     iecho = (struct icmp_echo_hdr *)p->payload;
 190     ip_addr_copy(iphdr->src, *ip_current_dest_addr());
 191     ip_addr_copy(iphdr->dest, *ip_current_src_addr());
 192     ICMPH_TYPE_SET(iecho, ICMP_ER);
 193     /* adjust the checksum */
 194     if (iecho->chksum >= PP_HTONS(0xffffU - (ICMP_ECHO << 8))) {
 195       iecho->chksum += PP_HTONS(ICMP_ECHO << 8) + 1;
 196     } else {
 197       iecho->chksum += PP_HTONS(ICMP_ECHO << 8);
 198     }
 199
 200     /* Set the correct TTL and recalculate the header checksum. */
 201     IPH_TTL_SET(iphdr, ICMP_TTL);
 202     IPH_CHKSUM_SET(iphdr, 0);
 203 #if CHECKSUM_GEN_IP
 204     IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
 205 #endif /* CHECKSUM_GEN_IP */
 206
 207     ICMP_STATS_INC(icmp.xmit);
 208     /* increase number of messages attempted to send */
 209     snmp_inc_icmpoutmsgs();
 210     /* increase number of echo replies attempted to send */
 211     snmp_inc_icmpoutechoreps();
 212
 213     if(pbuf_header(p, hlen)) {
 214       LWIP_ASSERT("Can't move over header in packet", 0);
 215     } else {
 216       err_t ret;
 217       /* send an ICMP packet, src addr is the dest addr of the curren packet */
 218       ret = ip_output_if(p, ip_current_dest_addr(), IP_HDRINCL,
 219                    ICMP_TTL, 0, IP_PROTO_ICMP, inp);
 220       if (ret != ERR_OK) {
 221         LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
 222       }
 223     }
 224     break;
 225   default:
 226     LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
 227                 (s16_t)type, (s16_t)code));
 228     ICMP_STATS_INC(icmp.proterr);
 229     ICMP_STATS_INC(icmp.drop);
 230   }
 231   pbuf_free(p);
 232   return;
 233 lenerr:
 234   pbuf_free(p);
 235   ICMP_STATS_INC(icmp.lenerr);
 236   snmp_inc_icmpinerrors();
 237   return;
 238 #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
 239 memerr:
 240   pbuf_free(p);
 241   ICMP_STATS_INC(icmp.err);
 242   snmp_inc_icmpinerrors();
 243   return;
 244 #endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
 245 }
 246
 247 /**
 248  * Send an icmp 'destination unreachable' packet, called from ip_input() if
 249  * the transport layer protocol is unknown and from udp_input() if the local
 250  * port is not bound.
 251  *
 252  * @param p the input packet for which the 'unreachable' should be sent,
 253  *          p->payload pointing to the IP header
 254  * @param t type of the 'unreachable' packet
 255  */
 256 void
 257 icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t)
 258 {
 259   icmp_send_response(p, ICMP_DUR, t);
 260 }
 261
 262 #if IP_FORWARD || IP_REASSEMBLY
 263 /**
 264  * Send a 'time exceeded' packet, called from ip_forward() if TTL is 0.
 265  *
 266  * @param p the input packet for which the 'time exceeded' should be sent,
 267  *          p->payload pointing to the IP header
 268  * @param t type of the 'time exceeded' packet
 269  */
 270 void
 271 icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t)
 272 {
 273   icmp_send_response(p, ICMP_TE, t);
 274 }
 275
 276 #endif /* IP_FORWARD || IP_REASSEMBLY */
 277
 278 /**
 279  * Send an icmp packet in response to an incoming packet.
 280  *
 281  * @param p the input packet for which the 'unreachable' should be sent,
 282  *          p->payload pointing to the IP header
 283  * @param type Type of the ICMP header
 284  * @param code Code of the ICMP header
 285  */
 286 static void
 287 icmp_send_response(struct pbuf *p, u8_t type, u8_t code)
 288 {
 289   struct pbuf *q;
 290   struct ip_hdr *iphdr;
 291   /* we can use the echo header here */
 292   struct icmp_echo_hdr *icmphdr;
 293   ip_addr_t iphdr_src;
 294
 295   /* ICMP header + IP header + 8 bytes of data */
 296   q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE,
 297                  PBUF_RAM);
 298   if (q == NULL) {
 299     LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n"));
 300     return;
 301   }
 302   LWIP_ASSERT("check that first pbuf can hold icmp message",
 303              (q->len >= (sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE)));
 304
 305   iphdr = (struct ip_hdr *)p->payload;
 306   LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));
 307   ip_addr_debug_print(ICMP_DEBUG, &(iphdr->src));
 308   LWIP_DEBUGF(ICMP_DEBUG, (" to "));
 309   ip_addr_debug_print(ICMP_DEBUG, &(iphdr->dest));
 310   LWIP_DEBUGF(ICMP_DEBUG, ("\n"));
 311
 312   icmphdr = (struct icmp_echo_hdr *)q->payload;
 313   icmphdr->type = type;
 314   icmphdr->code = code;
 315   icmphdr->id = 0;
 316   icmphdr->seqno = 0;
 317
 318   /* copy fields from original packet */
 319   SMEMCPY((u8_t *)q->payload + sizeof(struct icmp_echo_hdr), (u8_t *)p->payload,
 320           IP_HLEN + ICMP_DEST_UNREACH_DATASIZE);
 321
 322   /* calculate checksum */
 323   icmphdr->chksum = 0;
 324   icmphdr->chksum = inet_chksum(icmphdr, q->len);
 325   ICMP_STATS_INC(icmp.xmit);
 326   /* increase number of messages attempted to send */
 327   snmp_inc_icmpoutmsgs();
 328   /* increase number of destination unreachable messages attempted to send */
 329   snmp_inc_icmpouttimeexcds();
 330   ip_addr_copy(iphdr_src, iphdr->src);
 331   ip_output(q, NULL, &iphdr_src, ICMP_TTL, 0, IP_PROTO_ICMP);
 332   pbuf_free(q);
 333 }
 334
 335 #endif /* LWIP_ICMP */