/** | |
* @file | |
* ICMP - Internet Control Message Protocol | |
* | |
*/ | |
/* | |
* 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 "lwip/opt.h" | |
#if LWIP_ICMP /* don't build if not configured for use in lwipopts.h */ | |
#include "lwip/icmp.h" | |
#include "lwip/inet.h" | |
#include "lwip/inet_chksum.h" | |
#include "lwip/ip.h" | |
#include "lwip/def.h" | |
#include "lwip/stats.h" | |
#include "lwip/snmp.h" | |
#include <string.h> | |
/* The amount of data from the original packet to return in a dest-unreachable */ | |
#define ICMP_DEST_UNREACH_DATASIZE 8 | |
/** | |
* Processes ICMP input packets, called from ip_input(). | |
* | |
* Currently only processes icmp echo requests and sends | |
* out the echo response. | |
* | |
* @param p the icmp echo request packet, p->payload pointing to the ip header | |
* @param inp the netif on which this packet was received | |
*/ | |
void | |
icmp_input(struct pbuf *p, struct netif *inp) | |
{ | |
u8_t type; | |
#ifdef LWIP_DEBUG | |
u8_t code; | |
#endif /* LWIP_DEBUG */ | |
struct icmp_echo_hdr *iecho; | |
struct ip_hdr *iphdr; | |
struct ip_addr tmpaddr; | |
s16_t hlen; | |
ICMP_STATS_INC(icmp.recv); | |
snmp_inc_icmpinmsgs(); | |
iphdr = p->payload; | |
hlen = IPH_HL(iphdr) * 4; | |
if (pbuf_header(p, -hlen) || (p->tot_len < sizeof(u16_t)*2)) { | |
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len)); | |
goto lenerr; | |
} | |
type = *((u8_t *)p->payload); | |
#ifdef LWIP_DEBUG | |
code = *(((u8_t *)p->payload)+1); | |
#endif /* LWIP_DEBUG */ | |
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")); | |
goto lenerr; | |
} | |
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; | |
} | |
if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) { | |
/* p is not big enough to contain link headers | |
* allocate a new one and copy p into it | |
*/ | |
struct pbuf *r; | |
/* switch p->payload to ip header */ | |
if (pbuf_header(p, hlen)) { | |
LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0); | |
goto memerr; | |
} | |
/* allocate new packet buffer with space for link headers */ | |
r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM); | |
if (r == NULL) { | |
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n")); | |
goto memerr; | |
} | |
LWIP_ASSERT("check that first pbuf can hold struct the ICMP header", | |
(r->len >= hlen + sizeof(struct icmp_echo_hdr))); | |
/* copy the whole packet including ip header */ | |
if (pbuf_copy(r, p) != ERR_OK) { | |
LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0); | |
goto memerr; | |
} | |
iphdr = r->payload; | |
/* switch r->payload back to icmp header */ | |
if (pbuf_header(r, -hlen)) { | |
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0); | |
goto memerr; | |
} | |
/* free the original p */ | |
pbuf_free(p); | |
/* we now have an identical copy of p that has room for link headers */ | |
p = r; | |
} else { | |
/* restore p->payload to point to icmp header */ | |
if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) { | |
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0); | |
goto memerr; | |
} | |
} | |
/* At this point, all checks are OK. */ | |
/* We generate an answer by switching the dest and src ip addresses, | |
* setting the icmp type to ECHO_RESPONSE and updating the checksum. */ | |
iecho = p->payload; | |
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); | |
} | |
/* Set the correct TTL and recalculate the header checksum. */ | |
IPH_TTL_SET(iphdr, ICMP_TTL); | |
IPH_CHKSUM_SET(iphdr, 0); | |
#if CHECKSUM_GEN_IP | |
IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN)); | |
#endif /* CHECKSUM_GEN_IP */ | |
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(); | |
if(pbuf_header(p, hlen)) { | |
LWIP_ASSERT("Can't move over header in packet", 0); | |
} else { | |
err_t ret; | |
ret = ip_output_if(p, &(iphdr->src), IP_HDRINCL, | |
ICMP_TTL, 0, IP_PROTO_ICMP, inp); | |
if (ret != ERR_OK) { | |
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret)); | |
} | |
} | |
break; | |
default: | |
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n", | |
(s16_t)type, (s16_t)code)); | |
ICMP_STATS_INC(icmp.proterr); | |
ICMP_STATS_INC(icmp.drop); | |
} | |
pbuf_free(p); | |
return; | |
lenerr: | |
pbuf_free(p); | |
ICMP_STATS_INC(icmp.lenerr); | |
snmp_inc_icmpinerrors(); | |
return; | |
memerr: | |
pbuf_free(p); | |
ICMP_STATS_INC(icmp.err); | |
snmp_inc_icmpinerrors(); | |
return; | |
} | |
/** | |
* Send an icmp 'destination unreachable' packet, called from ip_input() if | |
* the transport layer protocol is unknown and from udp_input() if the local | |
* port is not bound. | |
* | |
* @param p the input packet for which the 'unreachable' should be sent, | |
* p->payload pointing to the IP header | |
* @param t type of the 'unreachable' packet | |
*/ | |
void | |
icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t) | |
{ | |
struct pbuf *q; | |
struct ip_hdr *iphdr; | |
struct icmp_dur_hdr *idur; | |
/* ICMP header + IP header + 8 bytes of data */ | |
q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_dur_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE, | |
PBUF_RAM); | |
if (q == NULL) { | |
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_dest_unreach: failed to allocate pbuf for ICMP packet.\n")); | |
return; | |
} | |
LWIP_ASSERT("check that first pbuf can hold icmp message", | |
(q->len >= (sizeof(struct icmp_dur_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE))); | |
iphdr = p->payload; | |
idur = q->payload; | |
ICMPH_TYPE_SET(idur, ICMP_DUR); | |
ICMPH_CODE_SET(idur, t); | |
SMEMCPY((u8_t *)q->payload + sizeof(struct icmp_dur_hdr), p->payload, | |
IP_HLEN + ICMP_DEST_UNREACH_DATASIZE); | |
/* 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_FORWARD || IP_REASSEMBLY | |
/** | |
* Send a 'time exceeded' packet, called from ip_forward() if TTL is 0. | |
* | |
* @param p the input packet for which the 'time exceeded' should be sent, | |
* p->payload pointing to the IP header | |
* @param t type of the 'time exceeded' packet | |
*/ | |
void | |
icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t) | |
{ | |
struct pbuf *q; | |
struct ip_hdr *iphdr; | |
struct icmp_te_hdr *tehdr; | |
/* ICMP header + IP header + 8 bytes of data */ | |
q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_dur_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE, | |
PBUF_RAM); | |
if (q == NULL) { | |
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n")); | |
return; | |
} | |
LWIP_ASSERT("check that first pbuf can hold icmp message", | |
(q->len >= (sizeof(struct icmp_dur_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE))); | |
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 */ | |
SMEMCPY((u8_t *)q->payload + sizeof(struct icmp_dur_hdr), (u8_t *)p->payload, | |
IP_HLEN + ICMP_DEST_UNREACH_DATASIZE); | |
/* 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 */ | |
#endif /* LWIP_ICMP */ |