339 lines
11 KiB
C
339 lines
11 KiB
C
/**
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* @file
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* ICMP - Internet Control Message Protocol
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*
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*/
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/*
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* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* This file is part of the lwIP TCP/IP stack.
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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*/
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/* Some ICMP messages should be passed to the transport protocols. This
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is not implemented. */
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#include "lwip/opt.h"
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#if LWIP_ICMP /* don't build if not configured for use in lwipopts.h */
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#include "lwip/icmp.h"
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#include "lwip/inet_chksum.h"
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#include "lwip/ip.h"
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#include "lwip/def.h"
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#include "lwip/stats.h"
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#include "lwip/snmp.h"
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#include <string.h>
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/** Small optimization: set to 0 if incoming PBUF_POOL pbuf always can be
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* used to modify and send a response packet (and to 1 if this is not the case,
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* e.g. when link header is stripped of when receiving) */
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#ifndef LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
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#define LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN 1
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#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
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/* The amount of data from the original packet to return in a dest-unreachable */
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#define ICMP_DEST_UNREACH_DATASIZE 8
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static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code);
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/**
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* Processes ICMP input packets, called from ip_input().
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*
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* Currently only processes icmp echo requests and sends
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* out the echo response.
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*
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* @param p the icmp echo request packet, p->payload pointing to the icmp header
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* @param inp the netif on which this packet was received
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*/
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void
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icmp_input(struct pbuf *p, struct netif *inp)
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{
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u8_t type;
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#ifdef LWIP_DEBUG
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u8_t code;
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#endif /* LWIP_DEBUG */
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struct icmp_echo_hdr *iecho;
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struct ip_hdr *iphdr;
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s16_t hlen;
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ICMP_STATS_INC(icmp.recv);
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snmp_inc_icmpinmsgs();
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iphdr = (struct ip_hdr *)ip_current_header();
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hlen = IPH_HL(iphdr) * 4;
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if (p->len < sizeof(u16_t)*2) {
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%"U16_F" bytes) received\n", p->tot_len));
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goto lenerr;
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}
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type = *((u8_t *)p->payload);
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#ifdef LWIP_DEBUG
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code = *(((u8_t *)p->payload)+1);
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#endif /* LWIP_DEBUG */
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switch (type) {
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case ICMP_ER:
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/* This is OK, echo reply might have been parsed by a raw PCB
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(as obviously, an echo request has been sent, too). */
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break;
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case ICMP_ECHO:
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#if !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING
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{
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int accepted = 1;
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#if !LWIP_MULTICAST_PING
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/* multicast destination address? */
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if (ip_addr_ismulticast(ip_current_dest_addr())) {
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accepted = 0;
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}
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#endif /* LWIP_MULTICAST_PING */
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#if !LWIP_BROADCAST_PING
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/* broadcast destination address? */
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if (ip_addr_isbroadcast(ip_current_dest_addr(), inp)) {
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accepted = 0;
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}
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#endif /* LWIP_BROADCAST_PING */
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/* broadcast or multicast destination address not acceptd? */
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if (!accepted) {
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast or broadcast pings\n"));
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ICMP_STATS_INC(icmp.err);
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pbuf_free(p);
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return;
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}
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}
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#endif /* !LWIP_MULTICAST_PING || !LWIP_BROADCAST_PING */
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
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if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
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goto lenerr;
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}
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if (inet_chksum_pbuf(p) != 0) {
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
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pbuf_free(p);
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ICMP_STATS_INC(icmp.chkerr);
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snmp_inc_icmpinerrors();
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return;
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}
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#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
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if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
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/* p is not big enough to contain link headers
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* allocate a new one and copy p into it
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*/
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struct pbuf *r;
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/* switch p->payload to ip header */
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if (pbuf_header(p, hlen)) {
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LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
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goto memerr;
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}
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/* allocate new packet buffer with space for link headers */
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r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
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if (r == NULL) {
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
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goto memerr;
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}
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LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
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(r->len >= hlen + sizeof(struct icmp_echo_hdr)));
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/* copy the whole packet including ip header */
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if (pbuf_copy(r, p) != ERR_OK) {
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LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
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goto memerr;
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}
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iphdr = (struct ip_hdr *)r->payload;
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/* switch r->payload back to icmp header */
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if (pbuf_header(r, -hlen)) {
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LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
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goto memerr;
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}
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/* free the original p */
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pbuf_free(p);
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/* we now have an identical copy of p that has room for link headers */
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p = r;
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} else {
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/* restore p->payload to point to icmp header */
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if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN))) {
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LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
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goto memerr;
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}
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}
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#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
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/* At this point, all checks are OK. */
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/* We generate an answer by switching the dest and src ip addresses,
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* setting the icmp type to ECHO_RESPONSE and updating the checksum. */
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iecho = (struct icmp_echo_hdr *)p->payload;
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ip_addr_copy(iphdr->src, *ip_current_dest_addr());
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ip_addr_copy(iphdr->dest, *ip_current_src_addr());
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ICMPH_TYPE_SET(iecho, ICMP_ER);
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#if CHECKSUM_GEN_ICMP
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/* adjust the checksum */
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if (iecho->chksum >= PP_HTONS(0xffffU - (ICMP_ECHO << 8))) {
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iecho->chksum += PP_HTONS(ICMP_ECHO << 8) + 1;
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} else {
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iecho->chksum += PP_HTONS(ICMP_ECHO << 8);
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}
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#else /* CHECKSUM_GEN_ICMP */
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iecho->chksum = 0;
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#endif /* CHECKSUM_GEN_ICMP */
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/* Set the correct TTL and recalculate the header checksum. */
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IPH_TTL_SET(iphdr, ICMP_TTL);
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IPH_CHKSUM_SET(iphdr, 0);
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#if CHECKSUM_GEN_IP
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IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
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#endif /* CHECKSUM_GEN_IP */
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ICMP_STATS_INC(icmp.xmit);
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/* increase number of messages attempted to send */
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snmp_inc_icmpoutmsgs();
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/* increase number of echo replies attempted to send */
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snmp_inc_icmpoutechoreps();
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if(pbuf_header(p, hlen)) {
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LWIP_ASSERT("Can't move over header in packet", 0);
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} else {
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err_t ret;
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/* send an ICMP packet, src addr is the dest addr of the curren packet */
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ret = ip_output_if(p, ip_current_dest_addr(), IP_HDRINCL,
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ICMP_TTL, 0, IP_PROTO_ICMP, inp);
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if (ret != ERR_OK) {
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %c.\n", ret));
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}
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}
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break;
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default:
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %"S16_F" code %"S16_F" not supported.\n",
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(s16_t)type, (s16_t)code));
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ICMP_STATS_INC(icmp.proterr);
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ICMP_STATS_INC(icmp.drop);
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}
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pbuf_free(p);
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return;
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lenerr:
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pbuf_free(p);
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ICMP_STATS_INC(icmp.lenerr);
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snmp_inc_icmpinerrors();
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return;
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#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
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memerr:
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pbuf_free(p);
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ICMP_STATS_INC(icmp.err);
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snmp_inc_icmpinerrors();
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return;
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#endif /* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
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}
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/**
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* Send an icmp 'destination unreachable' packet, called from ip_input() if
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* the transport layer protocol is unknown and from udp_input() if the local
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* port is not bound.
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*
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* @param p the input packet for which the 'unreachable' should be sent,
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* p->payload pointing to the IP header
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* @param t type of the 'unreachable' packet
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*/
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void
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icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t)
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{
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icmp_send_response(p, ICMP_DUR, t);
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}
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#if IP_FORWARD || IP_REASSEMBLY
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/**
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* Send a 'time exceeded' packet, called from ip_forward() if TTL is 0.
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*
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* @param p the input packet for which the 'time exceeded' should be sent,
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* p->payload pointing to the IP header
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* @param t type of the 'time exceeded' packet
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*/
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void
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icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t)
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{
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icmp_send_response(p, ICMP_TE, t);
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}
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#endif /* IP_FORWARD || IP_REASSEMBLY */
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/**
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* Send an icmp packet in response to an incoming packet.
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*
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* @param p the input packet for which the 'unreachable' should be sent,
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* p->payload pointing to the IP header
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* @param type Type of the ICMP header
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* @param code Code of the ICMP header
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*/
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static void
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icmp_send_response(struct pbuf *p, u8_t type, u8_t code)
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{
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struct pbuf *q;
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struct ip_hdr *iphdr;
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/* we can use the echo header here */
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struct icmp_echo_hdr *icmphdr;
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ip_addr_t iphdr_src;
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/* ICMP header + IP header + 8 bytes of data */
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q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE,
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PBUF_RAM);
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if (q == NULL) {
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n"));
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return;
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}
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LWIP_ASSERT("check that first pbuf can hold icmp message",
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(q->len >= (sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE)));
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iphdr = (struct ip_hdr *)p->payload;
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LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));
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ip_addr_debug_print(ICMP_DEBUG, &(iphdr->src));
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LWIP_DEBUGF(ICMP_DEBUG, (" to "));
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ip_addr_debug_print(ICMP_DEBUG, &(iphdr->dest));
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LWIP_DEBUGF(ICMP_DEBUG, ("\n"));
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icmphdr = (struct icmp_echo_hdr *)q->payload;
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icmphdr->type = type;
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icmphdr->code = code;
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icmphdr->id = 0;
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icmphdr->seqno = 0;
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/* copy fields from original packet */
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SMEMCPY((u8_t *)q->payload + sizeof(struct icmp_echo_hdr), (u8_t *)p->payload,
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IP_HLEN + ICMP_DEST_UNREACH_DATASIZE);
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/* calculate checksum */
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icmphdr->chksum = 0;
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icmphdr->chksum = inet_chksum(icmphdr, q->len);
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ICMP_STATS_INC(icmp.xmit);
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/* increase number of messages attempted to send */
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snmp_inc_icmpoutmsgs();
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/* increase number of destination unreachable messages attempted to send */
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snmp_inc_icmpouttimeexcds();
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ip_addr_copy(iphdr_src, iphdr->src);
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ip_output(q, NULL, &iphdr_src, ICMP_TTL, 0, IP_PROTO_ICMP);
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pbuf_free(q);
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}
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#endif /* LWIP_ICMP */
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