| 1 | /*
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| 2 | * Copyright (c) 1982, 1986, 1988, 1993
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| 3 | * The Regents of the University of California. All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | * 1. Redistributions of source code must retain the above copyright
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| 9 | * notice, this list of conditions and the following disclaimer.
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| 10 | * 2. Redistributions in binary form must reproduce the above copyright
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| 11 | * notice, this list of conditions and the following disclaimer in the
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| 12 | * documentation and/or other materials provided with the distribution.
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| 13 | * 3. All advertising materials mentioning features or use of this software
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| 14 | * must display the following acknowledgement:
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| 15 | * This product includes software developed by the University of
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| 16 | * California, Berkeley and its contributors.
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| 17 | * 4. Neither the name of the University nor the names of its contributors
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| 18 | * may be used to endorse or promote products derived from this software
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| 19 | * without specific prior written permission.
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| 20 | *
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| 21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 31 | * SUCH DAMAGE.
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| 32 | *
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| 33 | * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
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| 34 | * ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
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| 35 | */
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| 36 |
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| 37 | #include "slirp.h"
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| 38 | #include "ip_icmp.h"
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| 39 |
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| 40 |
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| 41 | /* The message sent when emulating PING */
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| 42 | /* Be nice and tell them it's just a psuedo-ping packet */
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| 43 | static const char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
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| 44 |
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| 45 | /* list of actions for icmp_error() on RX of an icmp message */
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| 46 | static const int icmp_flush[19] = {
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| 47 | /* ECHO REPLY (0) */ 0,
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| 48 | 1,
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| 49 | 1,
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| 50 | /* DEST UNREACH (3) */ 1,
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| 51 | /* SOURCE QUENCH (4)*/ 1,
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| 52 | /* REDIRECT (5) */ 1,
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| 53 | 1,
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| 54 | 1,
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| 55 | /* ECHO (8) */ 0,
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| 56 | /* ROUTERADVERT (9) */ 1,
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| 57 | /* ROUTERSOLICIT (10) */ 1,
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| 58 | /* TIME EXCEEDED (11) */ 1,
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| 59 | /* PARAMETER PROBLEM (12) */ 1,
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| 60 | /* TIMESTAMP (13) */ 0,
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| 61 | /* TIMESTAMP REPLY (14) */ 0,
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| 62 | /* INFO (15) */ 0,
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| 63 | /* INFO REPLY (16) */ 0,
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| 64 | /* ADDR MASK (17) */ 0,
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| 65 | /* ADDR MASK REPLY (18) */ 0
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| 66 | };
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| 67 |
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| 68 | /*
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| 69 | * Process a received ICMP message.
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| 70 | */
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| 71 | void
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| 72 | icmp_input(PNATState pData, struct mbuf *m, int hlen)
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| 73 | {
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| 74 | register struct icmp *icp;
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| 75 | register struct ip *ip=mtod(m, struct ip *);
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| 76 | int icmplen=ip->ip_len;
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| 77 | /* int code; */
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| 78 |
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| 79 | DEBUG_CALL("icmp_input");
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| 80 | DEBUG_ARG("m = %lx", (long )m);
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| 81 | DEBUG_ARG("m_len = %d", m->m_len);
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| 82 |
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| 83 | icmpstat.icps_received++;
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| 84 |
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| 85 | /*
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| 86 | * Locate icmp structure in mbuf, and check
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| 87 | * that its not corrupted and of at least minimum length.
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| 88 | */
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| 89 | if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
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| 90 | icmpstat.icps_tooshort++;
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| 91 | freeit:
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| 92 | m_freem(pData, m);
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| 93 | goto end_error;
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| 94 | }
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| 95 |
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| 96 | m->m_len -= hlen;
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| 97 | m->m_data += hlen;
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| 98 | icp = mtod(m, struct icmp *);
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| 99 | if (cksum(m, icmplen)) {
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| 100 | icmpstat.icps_checksum++;
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| 101 | goto freeit;
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| 102 | }
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| 103 | m->m_len += hlen;
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| 104 | m->m_data -= hlen;
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| 105 |
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| 106 | /* icmpstat.icps_inhist[icp->icmp_type]++; */
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| 107 | /* code = icp->icmp_code; */
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| 108 |
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| 109 | DEBUG_ARG("icmp_type = %d", icp->icmp_type);
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| 110 | switch (icp->icmp_type) {
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| 111 | case ICMP_ECHO:
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| 112 | icp->icmp_type = ICMP_ECHOREPLY;
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| 113 | ip->ip_len += hlen; /* since ip_input subtracts this */
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| 114 | if (ip->ip_dst.s_addr == alias_addr.s_addr) {
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| 115 | icmp_reflect(pData, m);
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| 116 | } else {
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| 117 | struct socket *so;
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| 118 | struct sockaddr_in addr;
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| 119 | if ((so = socreate()) == NULL) goto freeit;
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| 120 | if(udp_attach(pData, so) == -1) {
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| 121 | DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
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| 122 | errno,strerror(errno)));
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| 123 | sofree(pData, so);
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| 124 | m_free(pData, m);
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| 125 | goto end_error;
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| 126 | }
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| 127 | so->so_m = m;
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| 128 | so->so_faddr = ip->ip_dst;
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| 129 | so->so_fport = htons(7);
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| 130 | so->so_laddr = ip->ip_src;
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| 131 | so->so_lport = htons(9);
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| 132 | so->so_iptos = ip->ip_tos;
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| 133 | so->so_type = IPPROTO_ICMP;
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| 134 | so->so_state = SS_ISFCONNECTED;
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| 135 |
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| 136 | /* Send the packet */
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| 137 | addr.sin_family = AF_INET;
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| 138 | if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
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| 139 | /* It's an alias */
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| 140 | switch(ntohl(so->so_faddr.s_addr) & 0xff) {
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| 141 | case CTL_DNS:
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| 142 | addr.sin_addr = dns_addr;
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| 143 | break;
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| 144 | case CTL_ALIAS:
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| 145 | default:
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| 146 | addr.sin_addr = loopback_addr;
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| 147 | break;
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| 148 | }
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| 149 | } else {
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| 150 | addr.sin_addr = so->so_faddr;
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| 151 | }
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| 152 | addr.sin_port = so->so_fport;
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| 153 | if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
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| 154 | (struct sockaddr *)&addr, sizeof(addr)) == -1) {
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| 155 | DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
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| 156 | errno,strerror(errno)));
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| 157 | icmp_error(pData, m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
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| 158 | udp_detach(pData, so);
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| 159 | }
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| 160 | } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
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| 161 | break;
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| 162 | case ICMP_UNREACH:
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| 163 | /* XXX? report error? close socket? */
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| 164 | case ICMP_TIMXCEED:
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| 165 | case ICMP_PARAMPROB:
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| 166 | case ICMP_SOURCEQUENCH:
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| 167 | case ICMP_TSTAMP:
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| 168 | case ICMP_MASKREQ:
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| 169 | case ICMP_REDIRECT:
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| 170 | icmpstat.icps_notsupp++;
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| 171 | m_freem(pData, m);
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| 172 | break;
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| 173 |
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| 174 | default:
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| 175 | icmpstat.icps_badtype++;
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| 176 | m_freem(pData, m);
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| 177 | } /* swith */
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| 178 |
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| 179 | end_error:
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| 180 | /* m is m_free()'d xor put in a socket xor or given to ip_send */
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| 181 | return;
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| 182 | }
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| 183 |
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| 184 |
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| 185 | /*
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| 186 | * Send an ICMP message in response to a situation
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| 187 | *
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| 188 | * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
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| 189 | * MUST NOT change this header information.
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| 190 | * MUST NOT reply to a multicast/broadcast IP address.
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| 191 | * MUST NOT reply to a multicast/broadcast MAC address.
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| 192 | * MUST reply to only the first fragment.
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| 193 | */
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| 194 | /*
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| 195 | * Send ICMP_UNREACH back to the source regarding msrc.
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| 196 | * mbuf *msrc is used as a template, but is NOT m_free()'d.
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| 197 | * It is reported as the bad ip packet. The header should
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| 198 | * be fully correct and in host byte order.
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| 199 | * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
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| 200 | * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
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| 201 | */
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| 202 |
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| 203 | #define ICMP_MAXDATALEN (IP_MSS-28)
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| 204 | void icmp_error(PNATState pData, struct mbuf *msrc, u_char type, u_char code, int minsize, char *message)
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| 205 | {
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| 206 | unsigned hlen, shlen, s_ip_len;
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| 207 | register struct ip *ip;
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| 208 | register struct icmp *icp;
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| 209 | register struct mbuf *m;
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| 210 |
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| 211 | DEBUG_CALL("icmp_error");
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| 212 | DEBUG_ARG("msrc = %lx", (long )msrc);
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| 213 | DEBUG_ARG("msrc_len = %d", msrc->m_len);
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| 214 |
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| 215 | if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
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| 216 |
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| 217 | /* check msrc */
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| 218 | if(!msrc) goto end_error;
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| 219 | ip = mtod(msrc, struct ip *);
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| 220 | #if DEBUG
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| 221 | { char bufa[20], bufb[20];
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| 222 | strcpy(bufa, inet_ntoa(ip->ip_src));
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| 223 | strcpy(bufb, inet_ntoa(ip->ip_dst));
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| 224 | DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
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| 225 | }
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| 226 | #endif
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| 227 | if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
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| 228 |
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| 229 | shlen=ip->ip_hl << 2;
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| 230 | s_ip_len=ip->ip_len;
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| 231 | if(ip->ip_p == IPPROTO_ICMP) {
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| 232 | icp = (struct icmp *)((char *)ip + shlen);
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| 233 | /*
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| 234 | * Assume any unknown ICMP type is an error. This isn't
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| 235 | * specified by the RFC, but think about it..
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| 236 | */
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| 237 | if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
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| 238 | }
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| 239 |
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| 240 | /* make a copy */
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| 241 | if(!(m=m_get(pData))) goto end_error; /* get mbuf */
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| 242 | { int new_m_size;
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| 243 | new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
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| 244 | if(new_m_size>m->m_size) m_inc(m, new_m_size);
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| 245 | }
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| 246 | memcpy(m->m_data, msrc->m_data, msrc->m_len);
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| 247 | m->m_len = msrc->m_len; /* copy msrc to m */
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| 248 |
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| 249 | /* make the header of the reply packet */
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| 250 | ip = mtod(m, struct ip *);
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| 251 | hlen= sizeof(struct ip ); /* no options in reply */
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| 252 |
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| 253 | /* fill in icmp */
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| 254 | m->m_data += hlen;
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| 255 | m->m_len -= hlen;
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| 256 |
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| 257 | icp = mtod(m, struct icmp *);
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| 258 |
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| 259 | if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
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| 260 | else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
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| 261 | s_ip_len=ICMP_MAXDATALEN;
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| 262 |
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| 263 | m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
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| 264 |
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| 265 | /* min. size = 8+sizeof(struct ip)+8 */
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| 266 |
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| 267 | icp->icmp_type = type;
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| 268 | icp->icmp_code = code;
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| 269 | icp->icmp_id = 0;
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| 270 | icp->icmp_seq = 0;
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| 271 |
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| 272 | memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
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| 273 | HTONS(icp->icmp_ip.ip_len);
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| 274 | HTONS(icp->icmp_ip.ip_id);
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| 275 | HTONS(icp->icmp_ip.ip_off);
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| 276 |
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| 277 | #if DEBUG
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| 278 | if(message) { /* DEBUG : append message to ICMP packet */
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| 279 | int message_len;
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| 280 | char *cpnt;
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| 281 | message_len=strlen(message);
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| 282 | if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
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| 283 | cpnt=(char *)m->m_data+m->m_len;
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| 284 | memcpy(cpnt, message, message_len);
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| 285 | m->m_len+=message_len;
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| 286 | }
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| 287 | #endif
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| 288 |
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| 289 | icp->icmp_cksum = 0;
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| 290 | icp->icmp_cksum = cksum(m, m->m_len);
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| 291 |
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| 292 | m->m_data -= hlen;
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| 293 | m->m_len += hlen;
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| 294 |
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| 295 | /* fill in ip */
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| 296 | ip->ip_hl = hlen >> 2;
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| 297 | ip->ip_len = m->m_len;
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| 298 |
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| 299 | ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */
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| 300 |
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| 301 | ip->ip_ttl = MAXTTL;
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| 302 | ip->ip_p = IPPROTO_ICMP;
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| 303 | ip->ip_dst = ip->ip_src; /* ip adresses */
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| 304 | ip->ip_src = alias_addr;
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| 305 |
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| 306 | (void ) ip_output(pData, (struct socket *)NULL, m);
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| 307 |
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| 308 | icmpstat.icps_reflect++;
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| 309 |
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| 310 | end_error:
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| 311 | return;
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| 312 | }
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| 313 | #undef ICMP_MAXDATALEN
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| 314 |
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| 315 | /*
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| 316 | * Reflect the ip packet back to the source
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| 317 | */
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| 318 | void
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| 319 | icmp_reflect(PNATState pData, struct mbuf *m)
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| 320 | {
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| 321 | register struct ip *ip = mtod(m, struct ip *);
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| 322 | int hlen = ip->ip_hl << 2;
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| 323 | int optlen = hlen - sizeof(struct ip );
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| 324 | register struct icmp *icp;
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| 325 |
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| 326 | /*
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| 327 | * Send an icmp packet back to the ip level,
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| 328 | * after supplying a checksum.
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| 329 | */
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| 330 | m->m_data += hlen;
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| 331 | m->m_len -= hlen;
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| 332 | icp = mtod(m, struct icmp *);
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| 333 |
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| 334 | icp->icmp_cksum = 0;
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| 335 | icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
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| 336 |
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| 337 | m->m_data -= hlen;
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| 338 | m->m_len += hlen;
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| 339 |
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| 340 | /* fill in ip */
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| 341 | if (optlen > 0) {
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| 342 | /*
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| 343 | * Strip out original options by copying rest of first
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| 344 | * mbuf's data back, and adjust the IP length.
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| 345 | */
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| 346 | memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
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| 347 | (unsigned )(m->m_len - hlen));
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| 348 | hlen -= optlen;
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| 349 | ip->ip_hl = hlen >> 2;
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| 350 | ip->ip_len -= optlen;
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| 351 | m->m_len -= optlen;
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| 352 | }
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| 353 |
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| 354 | ip->ip_ttl = MAXTTL;
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| 355 | { /* swap */
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| 356 | struct in_addr icmp_dst;
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| 357 | icmp_dst = ip->ip_dst;
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| 358 | ip->ip_dst = ip->ip_src;
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| 359 | ip->ip_src = icmp_dst;
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| 360 | }
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| 361 |
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| 362 | (void ) ip_output(pData, (struct socket *)NULL, m);
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| 363 |
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| 364 | icmpstat.icps_reflect++;
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| 365 | }
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