/* * Copyright (c) 2001-2004 Swedish Institute of Computer Science. * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, *    this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright notice, *    this list of conditions and the following disclaimer in the documentation *    and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products *    derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY * OF SUCH DAMAGE. * * This file is part of the lwIP TCP/IP stack. * * Author: Adam Dunkels <adam@sics.se> * *//* Some ICMP messages should be passed to the transport protocols. This   is not implemented. */#include <string.h>#include "lwip/opt.h"#include "lwip/icmp.h"#include "lwip/inet.h"#include "lwip/ip.h"#include "lwip/def.h"#include "lwip/stats.h"#include "lwip/snmp.h"voidicmp_input(struct pbuf *p, struct netif *inp){  unsigned char type;  unsigned char code;  struct icmp_echo_hdr *iecho;  struct ip_hdr *iphdr;  struct ip_addr tmpaddr;  u16_t hlen;  ICMP_STATS_INC(icmp.recv);  snmp_inc_icmpinmsgs();  iphdr = p->payload;  hlen = IPH_HL(iphdr) * 4;  if (pbuf_header(p, -((s16_t)hlen)) || (p->tot_len < sizeof(u16_t)*2)) {    LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%u bytes) received\n", p->tot_len));    pbuf_free(p);    ICMP_STATS_INC(icmp.lenerr);    snmp_inc_icmpinerrors();    return;  }  type = *((u8_t *)p->payload);  code = *(((u8_t *)p->payload)+1);  switch (type) {  case ICMP_ECHO:    /* broadcast or multicast destination address? */    if (ip_addr_isbroadcast(&iphdr->dest, inp) || ip_addr_ismulticast(&iphdr->dest)) {      LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));      ICMP_STATS_INC(icmp.err);      pbuf_free(p);      return;    }    LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));    if (p->tot_len < sizeof(struct icmp_echo_hdr)) {      LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));      pbuf_free(p);      ICMP_STATS_INC(icmp.lenerr);      snmp_inc_icmpinerrors();      return;    }    iecho = p->payload;    if (inet_chksum_pbuf(p) != 0) {      LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));      pbuf_free(p);      ICMP_STATS_INC(icmp.chkerr);      snmp_inc_icmpinerrors();      return;    }    tmpaddr.addr = iphdr->src.addr;    iphdr->src.addr = iphdr->dest.addr;    iphdr->dest.addr = tmpaddr.addr;    ICMPH_TYPE_SET(iecho, ICMP_ER);    /* adjust the checksum */    if (iecho->chksum >= htons(0xffff - (ICMP_ECHO << 8))) {      iecho->chksum += htons(ICMP_ECHO << 8) + 1;    } else {      iecho->chksum += htons(ICMP_ECHO << 8);    }    ICMP_STATS_INC(icmp.xmit);    /* increase number of messages attempted to send */    snmp_inc_icmpoutmsgs();    /* increase number of echo replies attempted to send */    snmp_inc_icmpoutechoreps();    pbuf_header(p, hlen);    ip_output_if(p, &(iphdr->src), IP_HDRINCL,		 IPH_TTL(iphdr), 0, IP_PROTO_ICMP, inp);    break;  default:  LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %d code %d not supported.\n", (int)type, (int)code));    ICMP_STATS_INC(icmp.proterr);    ICMP_STATS_INC(icmp.drop);  }  pbuf_free(p);}voidicmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t){  struct pbuf *q;  struct ip_hdr *iphdr;  struct icmp_dur_hdr *idur;  q = pbuf_alloc(PBUF_IP, 8 + IP_HLEN + 8, PBUF_RAM);  /* ICMP header + IP header + 8 bytes of data */  iphdr = p->payload;  idur = q->payload;  ICMPH_TYPE_SET(idur, ICMP_DUR);  ICMPH_CODE_SET(idur, t);  memcpy((char *)q->payload + 8, p->payload, IP_HLEN + 8);  /* calculate checksum */  idur->chksum = 0;  idur->chksum = inet_chksum(idur, q->len);  ICMP_STATS_INC(icmp.xmit);  /* increase number of messages attempted to send */  snmp_inc_icmpoutmsgs();  /* increase number of destination unreachable messages attempted to send */  snmp_inc_icmpoutdestunreachs();  ip_output(q, NULL, &(iphdr->src),	    ICMP_TTL, 0, IP_PROTO_ICMP);  pbuf_free(q);}#if IP_FORWARDvoidicmp_time_exceeded(struct pbuf *p, enum icmp_te_type t){  struct pbuf *q;  struct ip_hdr *iphdr;  struct icmp_te_hdr *tehdr;  q = pbuf_alloc(PBUF_IP, 8 + IP_HLEN + 8, PBUF_RAM);  iphdr = p->payload;  LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));  ip_addr_debug_print(ICMP_DEBUG, &(iphdr->src));  LWIP_DEBUGF(ICMP_DEBUG, (" to "));  ip_addr_debug_print(ICMP_DEBUG, &(iphdr->dest));  LWIP_DEBUGF(ICMP_DEBUG, ("\n"));  tehdr = q->payload;  ICMPH_TYPE_SET(tehdr, ICMP_TE);  ICMPH_CODE_SET(tehdr, t);  /* copy fields from original packet */  memcpy((char *)q->payload + 8, (char *)p->payload, IP_HLEN + 8);  /* calculate checksum */  tehdr->chksum = 0;  tehdr->chksum = inet_chksum(tehdr, q->len);  ICMP_STATS_INC(icmp.xmit);  /* increase number of messages attempted to send */  snmp_inc_icmpoutmsgs();  /* increase number of destination unreachable messages attempted to send */  snmp_inc_icmpouttimeexcds();  ip_output(q, NULL, &(iphdr->src),	    ICMP_TTL, 0, IP_PROTO_ICMP);  pbuf_free(q);}#endif /* IP_FORWARD */