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This library is stripped down version of NetServices library. HTTP server and client function is NOT supported.

lwip/core/ipv4/icmp.c@0:dcf3c92487ca, 2011-07-20 (annotated)

Committer:: idinor
Date:: Wed Jul 20 11:45:39 2011 +0000
Revision:: 0:dcf3c92487ca

Who changed what in which revision?

User	Revision	Line number	New contents of line
idinor	0:dcf3c92487ca	1	/**
idinor	0:dcf3c92487ca	2	* @file
idinor	0:dcf3c92487ca	3	* ICMP - Internet Control Message Protocol
idinor	0:dcf3c92487ca	4	*
idinor	0:dcf3c92487ca	5	*/
idinor	0:dcf3c92487ca	6
idinor	0:dcf3c92487ca	7	/*
idinor	0:dcf3c92487ca	8	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
idinor	0:dcf3c92487ca	9	* All rights reserved.
idinor	0:dcf3c92487ca	10	*
idinor	0:dcf3c92487ca	11	* Redistribution and use in source and binary forms, with or without modification,
idinor	0:dcf3c92487ca	12	* are permitted provided that the following conditions are met:
idinor	0:dcf3c92487ca	13	*
idinor	0:dcf3c92487ca	14	* 1. Redistributions of source code must retain the above copyright notice,
idinor	0:dcf3c92487ca	15	* this list of conditions and the following disclaimer.
idinor	0:dcf3c92487ca	16	* 2. Redistributions in binary form must reproduce the above copyright notice,
idinor	0:dcf3c92487ca	17	* this list of conditions and the following disclaimer in the documentation
idinor	0:dcf3c92487ca	18	* and/or other materials provided with the distribution.
idinor	0:dcf3c92487ca	19	* 3. The name of the author may not be used to endorse or promote products
idinor	0:dcf3c92487ca	20	* derived from this software without specific prior written permission.
idinor	0:dcf3c92487ca	21	*
idinor	0:dcf3c92487ca	22	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
idinor	0:dcf3c92487ca	23	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
idinor	0:dcf3c92487ca	24	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
idinor	0:dcf3c92487ca	25	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
idinor	0:dcf3c92487ca	26	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
idinor	0:dcf3c92487ca	27	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
idinor	0:dcf3c92487ca	28	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
idinor	0:dcf3c92487ca	29	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
idinor	0:dcf3c92487ca	30	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
idinor	0:dcf3c92487ca	31	* OF SUCH DAMAGE.
idinor	0:dcf3c92487ca	32	*
idinor	0:dcf3c92487ca	33	* This file is part of the lwIP TCP/IP stack.
idinor	0:dcf3c92487ca	34	*
idinor	0:dcf3c92487ca	35	* Author: Adam Dunkels <adam@sics.se>
idinor	0:dcf3c92487ca	36	*
idinor	0:dcf3c92487ca	37	*/
idinor	0:dcf3c92487ca	38
idinor	0:dcf3c92487ca	39	/* Some ICMP messages should be passed to the transport protocols. This
idinor	0:dcf3c92487ca	40	is not implemented. */
idinor	0:dcf3c92487ca	41
idinor	0:dcf3c92487ca	42	#include "lwip/opt.h"
idinor	0:dcf3c92487ca	43
idinor	0:dcf3c92487ca	44	#if LWIP_ICMP /* don't build if not configured for use in lwipopts.h */
idinor	0:dcf3c92487ca	45
idinor	0:dcf3c92487ca	46	#include "lwip/icmp.h"
idinor	0:dcf3c92487ca	47	#include "lwip/inet_chksum.h"
idinor	0:dcf3c92487ca	48	#include "lwip/ip.h"
idinor	0:dcf3c92487ca	49	#include "lwip/def.h"
idinor	0:dcf3c92487ca	50	#include "lwip/stats.h"
idinor	0:dcf3c92487ca	51	#include "lwip/snmp.h"
idinor	0:dcf3c92487ca	52
idinor	0:dcf3c92487ca	53	#include <string.h>
idinor	0:dcf3c92487ca	54
idinor	0:dcf3c92487ca	55	/** Small optimization: set to 0 if incoming PBUF_POOL pbuf always can be
idinor	0:dcf3c92487ca	56	* used to modify and send a response packet (and to 1 if this is not the case,
idinor	0:dcf3c92487ca	57	* e.g. when link header is stripped of when receiving) */
idinor	0:dcf3c92487ca	58	#ifndef LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
idinor	0:dcf3c92487ca	59	#define LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN 1
idinor	0:dcf3c92487ca	60	#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
idinor	0:dcf3c92487ca	61
idinor	0:dcf3c92487ca	62	/* The amount of data from the original packet to return in a dest-unreachable */
idinor	0:dcf3c92487ca	63	#define ICMP_DEST_UNREACH_DATASIZE 8
idinor	0:dcf3c92487ca	64
idinor	0:dcf3c92487ca	65	static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code);
idinor	0:dcf3c92487ca	66
idinor	0:dcf3c92487ca	67	/**
idinor	0:dcf3c92487ca	68	* Processes ICMP input packets, called from ip_input().
idinor	0:dcf3c92487ca	69	*
idinor	0:dcf3c92487ca	70	* Currently only processes icmp echo requests and sends
idinor	0:dcf3c92487ca	71	* out the echo response.
idinor	0:dcf3c92487ca	72	*
idinor	0:dcf3c92487ca	73	* @param p the icmp echo request packet, p->payload pointing to the ip header
idinor	0:dcf3c92487ca	74	* @param inp the netif on which this packet was received
idinor	0:dcf3c92487ca	75	*/
idinor	0:dcf3c92487ca	76	void
idinor	0:dcf3c92487ca	77	icmp_input(struct pbuf p, struct netif inp)
idinor	0:dcf3c92487ca	78	{
idinor	0:dcf3c92487ca	79	u8_t type;
idinor	0:dcf3c92487ca	80	#ifdef LWIP_DEBUG
idinor	0:dcf3c92487ca	81	u8_t code;
idinor	0:dcf3c92487ca	82	#endif /* LWIP_DEBUG */
idinor	0:dcf3c92487ca	83	struct icmp_echo_hdr *iecho;
idinor	0:dcf3c92487ca	84	struct ip_hdr *iphdr;
idinor	0:dcf3c92487ca	85	s16_t hlen;
idinor	0:dcf3c92487ca	86
idinor	0:dcf3c92487ca	87	ICMP_STATS_INC(icmp.recv);
idinor	0:dcf3c92487ca	88	snmp_inc_icmpinmsgs();
idinor	0:dcf3c92487ca	89
idinor	0:dcf3c92487ca	90
idinor	0:dcf3c92487ca	91	iphdr = (struct ip_hdr *)p->payload;
idinor	0:dcf3c92487ca	92	hlen = IPH_HL(iphdr) * 4;
idinor	0:dcf3c92487ca	93	if (pbuf_header(p, -hlen) \|\| (p->tot_len < sizeof(u16_t)*2)) {
idinor	0:dcf3c92487ca	94	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
idinor	0:dcf3c92487ca	95	goto lenerr;
idinor	0:dcf3c92487ca	96	}
idinor	0:dcf3c92487ca	97
idinor	0:dcf3c92487ca	98	type = ((u8_t )p->payload);
idinor	0:dcf3c92487ca	99	#ifdef LWIP_DEBUG
idinor	0:dcf3c92487ca	100	code = (((u8_t )p->payload)+1);
idinor	0:dcf3c92487ca	101	#endif /* LWIP_DEBUG */
idinor	0:dcf3c92487ca	102	switch (type) {
idinor	0:dcf3c92487ca	103	case ICMP_ER:
idinor	0:dcf3c92487ca	104	/* This is OK, echo reply might have been parsed by a raw PCB
idinor	0:dcf3c92487ca	105	(as obviously, an echo request has been sent, too). */
idinor	0:dcf3c92487ca	106	break;
idinor	0:dcf3c92487ca	107	case ICMP_ECHO:
idinor	0:dcf3c92487ca	108	#if !LWIP_MULTICAST_PING \|\| !LWIP_BROADCAST_PING
idinor	0:dcf3c92487ca	109	{
idinor	0:dcf3c92487ca	110	int accepted = 1;
idinor	0:dcf3c92487ca	111	#if !LWIP_MULTICAST_PING
idinor	0:dcf3c92487ca	112	/* multicast destination address? */
idinor	0:dcf3c92487ca	113	if (ip_addr_ismulticast(&current_iphdr_dest)) {
idinor	0:dcf3c92487ca	114	accepted = 0;
idinor	0:dcf3c92487ca	115	}
idinor	0:dcf3c92487ca	116	#endif /* LWIP_MULTICAST_PING */
idinor	0:dcf3c92487ca	117	#if !LWIP_BROADCAST_PING
idinor	0:dcf3c92487ca	118	/* broadcast destination address? */
idinor	0:dcf3c92487ca	119	if (ip_addr_isbroadcast(&current_iphdr_dest, inp)) {
idinor	0:dcf3c92487ca	120	accepted = 0;
idinor	0:dcf3c92487ca	121	}
idinor	0:dcf3c92487ca	122	#endif /* LWIP_BROADCAST_PING */
idinor	0:dcf3c92487ca	123	/* broadcast or multicast destination address not acceptd? */
idinor	0:dcf3c92487ca	124	if (!accepted) {
idinor	0:dcf3c92487ca	125	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
idinor	0:dcf3c92487ca	126	ICMP_STATS_INC(icmp.err);
idinor	0:dcf3c92487ca	127	pbuf_free(p);
idinor	0:dcf3c92487ca	128	return;
idinor	0:dcf3c92487ca	129	}
idinor	0:dcf3c92487ca	130	}
idinor	0:dcf3c92487ca	131	#endif /* !LWIP_MULTICAST_PING \|\| !LWIP_BROADCAST_PING */
idinor	0:dcf3c92487ca	132	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
idinor	0:dcf3c92487ca	133	if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
idinor	0:dcf3c92487ca	134	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
idinor	0:dcf3c92487ca	135	goto lenerr;
idinor	0:dcf3c92487ca	136	}
idinor	0:dcf3c92487ca	137	if (inet_chksum_pbuf(p) != 0) {
idinor	0:dcf3c92487ca	138	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
idinor	0:dcf3c92487ca	139	pbuf_free(p);
idinor	0:dcf3c92487ca	140	ICMP_STATS_INC(icmp.chkerr);
idinor	0:dcf3c92487ca	141	snmp_inc_icmpinerrors();
idinor	0:dcf3c92487ca	142	return;
idinor	0:dcf3c92487ca	143	}
idinor	0:dcf3c92487ca	144	#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
idinor	0:dcf3c92487ca	145	if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
idinor	0:dcf3c92487ca	146	/* p is not big enough to contain link headers
idinor	0:dcf3c92487ca	147	* allocate a new one and copy p into it
idinor	0:dcf3c92487ca	148	*/
idinor	0:dcf3c92487ca	149	struct pbuf *r;
idinor	0:dcf3c92487ca	150	/* switch p->payload to ip header */
idinor	0:dcf3c92487ca	151	if (pbuf_header(p, hlen)) {
idinor	0:dcf3c92487ca	152	LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
idinor	0:dcf3c92487ca	153	goto memerr;
idinor	0:dcf3c92487ca	154	}
idinor	0:dcf3c92487ca	155	/* allocate new packet buffer with space for link headers */
idinor	0:dcf3c92487ca	156	r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
idinor	0:dcf3c92487ca	157	if (r == NULL) {
idinor	0:dcf3c92487ca	158	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
idinor	0:dcf3c92487ca	159	goto memerr;
idinor	0:dcf3c92487ca	160	}
idinor	0:dcf3c92487ca	161	LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
idinor	0:dcf3c92487ca	162	(r->len >= hlen + sizeof(struct icmp_echo_hdr)));
idinor	0:dcf3c92487ca	163	/* copy the whole packet including ip header */
idinor	0:dcf3c92487ca	164	if (pbuf_copy(r, p) != ERR_OK) {
idinor	0:dcf3c92487ca	165	LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
idinor	0:dcf3c92487ca	166	goto memerr;
idinor	0:dcf3c92487ca	167	}
idinor	0:dcf3c92487ca	168	iphdr = (struct ip_hdr *)r->payload;
idinor	0:dcf3c92487ca	169	/* switch r->payload back to icmp header */
idinor	0:dcf3c92487ca	170	if (pbuf_header(r, -hlen)) {
idinor	0:dcf3c92487ca	171	LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
idinor	0:dcf3c92487ca	172	goto memerr;
idinor	0:dcf3c92487ca	173	}
idinor	0:dcf3c92487ca	174	/* free the original p */
idinor	0:dcf3c92487ca	175	pbuf_free(p);
idinor	0:dcf3c92487ca	176	/* we now have an identical copy of p that has room for link headers */
idinor	0:dcf3c92487ca	177	p = r;
idinor	0:dcf3c92487ca	178	} else {
idinor	0:dcf3c92487ca	179	/* restore p->payload to point to icmp header */
idinor	0:dcf3c92487ca	180	if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
idinor	0:dcf3c92487ca	181	LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
idinor	0:dcf3c92487ca	182	goto memerr;
idinor	0:dcf3c92487ca	183	}
idinor	0:dcf3c92487ca	184	}
idinor	0:dcf3c92487ca	185	#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
idinor	0:dcf3c92487ca	186	/* At this point, all checks are OK. */
idinor	0:dcf3c92487ca	187	/* We generate an answer by switching the dest and src ip addresses,
idinor	0:dcf3c92487ca	188	* setting the icmp type to ECHO_RESPONSE and updating the checksum. */
idinor	0:dcf3c92487ca	189	iecho = (struct icmp_echo_hdr *)p->payload;
idinor	0:dcf3c92487ca	190	ip_addr_copy(iphdr->src, *ip_current_dest_addr());
idinor	0:dcf3c92487ca	191	ip_addr_copy(iphdr->dest, *ip_current_src_addr());
idinor	0:dcf3c92487ca	192	ICMPH_TYPE_SET(iecho, ICMP_ER);
idinor	0:dcf3c92487ca	193	/* adjust the checksum */
idinor	0:dcf3c92487ca	194	if (iecho->chksum >= PP_HTONS(0xffff - (ICMP_ECHO << 8))) {
idinor	0:dcf3c92487ca	195	iecho->chksum += PP_HTONS(ICMP_ECHO << 8) + 1;
idinor	0:dcf3c92487ca	196	} else {
idinor	0:dcf3c92487ca	197	iecho->chksum += PP_HTONS(ICMP_ECHO << 8);
idinor	0:dcf3c92487ca	198	}
idinor	0:dcf3c92487ca	199
idinor	0:dcf3c92487ca	200	/* Set the correct TTL and recalculate the header checksum. */
idinor	0:dcf3c92487ca	201	IPH_TTL_SET(iphdr, ICMP_TTL);
idinor	0:dcf3c92487ca	202	IPH_CHKSUM_SET(iphdr, 0);
idinor	0:dcf3c92487ca	203	#if CHECKSUM_GEN_IP
idinor	0:dcf3c92487ca	204	IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
idinor	0:dcf3c92487ca	205	#endif /* CHECKSUM_GEN_IP */
idinor	0:dcf3c92487ca	206
idinor	0:dcf3c92487ca	207	ICMP_STATS_INC(icmp.xmit);
idinor	0:dcf3c92487ca	208	/* increase number of messages attempted to send */
idinor	0:dcf3c92487ca	209	snmp_inc_icmpoutmsgs();
idinor	0:dcf3c92487ca	210	/* increase number of echo replies attempted to send */
idinor	0:dcf3c92487ca	211	snmp_inc_icmpoutechoreps();
idinor	0:dcf3c92487ca	212
idinor	0:dcf3c92487ca	213	if(pbuf_header(p, hlen)) {
idinor	0:dcf3c92487ca	214	LWIP_ASSERT("Can't move over header in packet", 0);
idinor	0:dcf3c92487ca	215	} else {
idinor	0:dcf3c92487ca	216	err_t ret;
idinor	0:dcf3c92487ca	217	/* send an ICMP packet, src addr is the dest addr of the curren packet */
idinor	0:dcf3c92487ca	218	ret = ip_output_if(p, ip_current_dest_addr(), IP_HDRINCL,
idinor	0:dcf3c92487ca	219	ICMP_TTL, 0, IP_PROTO_ICMP, inp);
idinor	0:dcf3c92487ca	220	if (ret != ERR_OK) {
idinor	0:dcf3c92487ca	221	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
idinor	0:dcf3c92487ca	222	}
idinor	0:dcf3c92487ca	223	}
idinor	0:dcf3c92487ca	224	break;
idinor	0:dcf3c92487ca	225	default:
idinor	0:dcf3c92487ca	226	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
idinor	0:dcf3c92487ca	227	(s16_t)type, (s16_t)code));
idinor	0:dcf3c92487ca	228	ICMP_STATS_INC(icmp.proterr);
idinor	0:dcf3c92487ca	229	ICMP_STATS_INC(icmp.drop);
idinor	0:dcf3c92487ca	230	}
idinor	0:dcf3c92487ca	231	pbuf_free(p);
idinor	0:dcf3c92487ca	232	return;
idinor	0:dcf3c92487ca	233	lenerr:
idinor	0:dcf3c92487ca	234	pbuf_free(p);
idinor	0:dcf3c92487ca	235	ICMP_STATS_INC(icmp.lenerr);
idinor	0:dcf3c92487ca	236	snmp_inc_icmpinerrors();
idinor	0:dcf3c92487ca	237	return;
idinor	0:dcf3c92487ca	238	#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
idinor	0:dcf3c92487ca	239	memerr:
idinor	0:dcf3c92487ca	240	pbuf_free(p);
idinor	0:dcf3c92487ca	241	ICMP_STATS_INC(icmp.err);
idinor	0:dcf3c92487ca	242	snmp_inc_icmpinerrors();
idinor	0:dcf3c92487ca	243	return;
idinor	0:dcf3c92487ca	244	#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
idinor	0:dcf3c92487ca	245	}
idinor	0:dcf3c92487ca	246
idinor	0:dcf3c92487ca	247	/**
idinor	0:dcf3c92487ca	248	* Send an icmp 'destination unreachable' packet, called from ip_input() if
idinor	0:dcf3c92487ca	249	* the transport layer protocol is unknown and from udp_input() if the local
idinor	0:dcf3c92487ca	250	* port is not bound.
idinor	0:dcf3c92487ca	251	*
idinor	0:dcf3c92487ca	252	* @param p the input packet for which the 'unreachable' should be sent,
idinor	0:dcf3c92487ca	253	* p->payload pointing to the IP header
idinor	0:dcf3c92487ca	254	* @param t type of the 'unreachable' packet
idinor	0:dcf3c92487ca	255	*/
idinor	0:dcf3c92487ca	256	void
idinor	0:dcf3c92487ca	257	icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t)
idinor	0:dcf3c92487ca	258	{
idinor	0:dcf3c92487ca	259	icmp_send_response(p, ICMP_DUR, t);
idinor	0:dcf3c92487ca	260	}
idinor	0:dcf3c92487ca	261
idinor	0:dcf3c92487ca	262	#if IP_FORWARD \|\| IP_REASSEMBLY
idinor	0:dcf3c92487ca	263	/**
idinor	0:dcf3c92487ca	264	* Send a 'time exceeded' packet, called from ip_forward() if TTL is 0.
idinor	0:dcf3c92487ca	265	*
idinor	0:dcf3c92487ca	266	* @param p the input packet for which the 'time exceeded' should be sent,
idinor	0:dcf3c92487ca	267	* p->payload pointing to the IP header
idinor	0:dcf3c92487ca	268	* @param t type of the 'time exceeded' packet
idinor	0:dcf3c92487ca	269	*/
idinor	0:dcf3c92487ca	270	void
idinor	0:dcf3c92487ca	271	icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t)
idinor	0:dcf3c92487ca	272	{
idinor	0:dcf3c92487ca	273	icmp_send_response(p, ICMP_TE, t);
idinor	0:dcf3c92487ca	274	}
idinor	0:dcf3c92487ca	275
idinor	0:dcf3c92487ca	276	#endif /* IP_FORWARD \|\| IP_REASSEMBLY */
idinor	0:dcf3c92487ca	277
idinor	0:dcf3c92487ca	278	/**
idinor	0:dcf3c92487ca	279	* Send an icmp packet in response to an incoming packet.
idinor	0:dcf3c92487ca	280	*
idinor	0:dcf3c92487ca	281	* @param p the input packet for which the 'unreachable' should be sent,
idinor	0:dcf3c92487ca	282	* p->payload pointing to the IP header
idinor	0:dcf3c92487ca	283	* @param type Type of the ICMP header
idinor	0:dcf3c92487ca	284	* @param code Code of the ICMP header
idinor	0:dcf3c92487ca	285	*/
idinor	0:dcf3c92487ca	286	static void
idinor	0:dcf3c92487ca	287	icmp_send_response(struct pbuf *p, u8_t type, u8_t code)
idinor	0:dcf3c92487ca	288	{
idinor	0:dcf3c92487ca	289	struct pbuf *q;
idinor	0:dcf3c92487ca	290	struct ip_hdr *iphdr;
idinor	0:dcf3c92487ca	291	/* we can use the echo header here */
idinor	0:dcf3c92487ca	292	struct icmp_echo_hdr *icmphdr;
idinor	0:dcf3c92487ca	293	ip_addr_t iphdr_src;
idinor	0:dcf3c92487ca	294
idinor	0:dcf3c92487ca	295	/* ICMP header + IP header + 8 bytes of data */
idinor	0:dcf3c92487ca	296	q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE,
idinor	0:dcf3c92487ca	297	PBUF_RAM);
idinor	0:dcf3c92487ca	298	if (q == NULL) {
idinor	0:dcf3c92487ca	299	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n"));
idinor	0:dcf3c92487ca	300	return;
idinor	0:dcf3c92487ca	301	}
idinor	0:dcf3c92487ca	302	LWIP_ASSERT("check that first pbuf can hold icmp message",
idinor	0:dcf3c92487ca	303	(q->len >= (sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE)));
idinor	0:dcf3c92487ca	304
idinor	0:dcf3c92487ca	305	iphdr = (struct ip_hdr *)p->payload;
idinor	0:dcf3c92487ca	306	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));
idinor	0:dcf3c92487ca	307	ip_addr_debug_print(ICMP_DEBUG, &(iphdr->src));
idinor	0:dcf3c92487ca	308	LWIP_DEBUGF(ICMP_DEBUG, (" to "));
idinor	0:dcf3c92487ca	309	ip_addr_debug_print(ICMP_DEBUG, &(iphdr->dest));
idinor	0:dcf3c92487ca	310	LWIP_DEBUGF(ICMP_DEBUG, ("\n"));
idinor	0:dcf3c92487ca	311
idinor	0:dcf3c92487ca	312	icmphdr = (struct icmp_echo_hdr *)q->payload;
idinor	0:dcf3c92487ca	313	icmphdr->type = type;
idinor	0:dcf3c92487ca	314	icmphdr->code = code;
idinor	0:dcf3c92487ca	315	icmphdr->id = 0;
idinor	0:dcf3c92487ca	316	icmphdr->seqno = 0;
idinor	0:dcf3c92487ca	317
idinor	0:dcf3c92487ca	318	/* copy fields from original packet */
idinor	0:dcf3c92487ca	319	SMEMCPY((u8_t )q->payload + sizeof(struct icmp_echo_hdr), (u8_t )p->payload,
idinor	0:dcf3c92487ca	320	IP_HLEN + ICMP_DEST_UNREACH_DATASIZE);
idinor	0:dcf3c92487ca	321
idinor	0:dcf3c92487ca	322	/* calculate checksum */
idinor	0:dcf3c92487ca	323	icmphdr->chksum = 0;
idinor	0:dcf3c92487ca	324	icmphdr->chksum = inet_chksum(icmphdr, q->len);
idinor	0:dcf3c92487ca	325	ICMP_STATS_INC(icmp.xmit);
idinor	0:dcf3c92487ca	326	/* increase number of messages attempted to send */
idinor	0:dcf3c92487ca	327	snmp_inc_icmpoutmsgs();
idinor	0:dcf3c92487ca	328	/* increase number of destination unreachable messages attempted to send */
idinor	0:dcf3c92487ca	329	snmp_inc_icmpouttimeexcds();
idinor	0:dcf3c92487ca	330	ip_addr_copy(iphdr_src, iphdr->src);
idinor	0:dcf3c92487ca	331	ip_output(q, NULL, &iphdr_src, ICMP_TTL, 0, IP_PROTO_ICMP);
idinor	0:dcf3c92487ca	332	pbuf_free(q);
idinor	0:dcf3c92487ca	333	}
idinor	0:dcf3c92487ca	334
idinor	0:dcf3c92487ca	335	#endif /* LWIP_ICMP */

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Type:	Library
Created:	20 Jul 2011
Imports:	35
Forks:	0
Commits:	1
Dependents:	1
Dependencies:	0
Followers:	1

lwip/core/ipv4/icmp.c@0:dcf3c92487ca, 2011-07-20 (annotated)

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