693 lines
18 KiB
C
693 lines
18 KiB
C
/*
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* Copyright (c) 1982, 1986, 1988, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
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* $Id: ip_icmp.c,v 1.26 1997/05/23 22:33:16 julian Exp $
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/mbuf.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <net/if.h>
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#include <net/route.h>
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#define _IP_VHL
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/in_var.h>
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#include <netinet/ip.h>
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#include <netinet/ip_icmp.h>
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#include <netinet/ip_var.h>
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#include <netinet/icmp_var.h>
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/*
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* ICMP routines: error generation, receive packet processing, and
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* routines to turnaround packets back to the originator, and
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* host table maintenance routines.
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*/
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static struct icmpstat icmpstat;
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SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RD,
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&icmpstat, icmpstat, "");
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static int icmpmaskrepl = 0;
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SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
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&icmpmaskrepl, 0, "");
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#ifdef ICMPPRINTFS
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int icmpprintfs = 0;
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#endif
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static void icmp_reflect __P((struct mbuf *));
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static void icmp_send __P((struct mbuf *, struct mbuf *));
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static int ip_next_mtu __P((int, int));
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extern struct protosw inetsw[];
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/*
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* Generate an error packet of type error
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* in response to bad packet ip.
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*/
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void
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icmp_error(n, type, code, dest, destifp)
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struct mbuf *n;
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int type, code;
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n_long dest;
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struct ifnet *destifp;
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{
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register struct ip *oip = mtod(n, struct ip *), *nip;
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register unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
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register struct icmp *icp;
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register struct mbuf *m;
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unsigned icmplen;
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#ifdef ICMPPRINTFS
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if (icmpprintfs)
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printf("icmp_error(%p, %x, %d)\n", oip, type, code);
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#endif
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if (type != ICMP_REDIRECT)
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icmpstat.icps_error++;
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/*
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* Don't send error if not the first fragment of message.
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* Don't error if the old packet protocol was ICMP
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* error message, only known informational types.
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*/
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if (oip->ip_off &~ (IP_MF|IP_DF))
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goto freeit;
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if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
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n->m_len >= oiplen + ICMP_MINLEN &&
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!ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
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icmpstat.icps_oldicmp++;
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goto freeit;
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}
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/* Don't send error in response to a multicast or broadcast packet */
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if (n->m_flags & (M_BCAST|M_MCAST))
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goto freeit;
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/*
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* First, formulate icmp message
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*/
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m = m_gethdr(M_DONTWAIT, MT_HEADER);
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if (m == NULL)
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goto freeit;
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icmplen = oiplen + min(8, oip->ip_len);
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m->m_len = icmplen + ICMP_MINLEN;
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MH_ALIGN(m, m->m_len);
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icp = mtod(m, struct icmp *);
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if ((u_int)type > ICMP_MAXTYPE)
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panic("icmp_error");
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icmpstat.icps_outhist[type]++;
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icp->icmp_type = type;
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if (type == ICMP_REDIRECT)
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icp->icmp_gwaddr.s_addr = dest;
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else {
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icp->icmp_void = 0;
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/*
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* The following assignments assume an overlay with the
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* zeroed icmp_void field.
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*/
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if (type == ICMP_PARAMPROB) {
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icp->icmp_pptr = code;
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code = 0;
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} else if (type == ICMP_UNREACH &&
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code == ICMP_UNREACH_NEEDFRAG && destifp) {
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icp->icmp_nextmtu = htons(destifp->if_mtu);
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}
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}
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icp->icmp_code = code;
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bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
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nip = &icp->icmp_ip;
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nip->ip_len = htons((u_short)(nip->ip_len + oiplen));
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/*
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* Now, copy old ip header (without options)
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* in front of icmp message.
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*/
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if (m->m_data - sizeof(struct ip) < m->m_pktdat)
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panic("icmp len");
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m->m_data -= sizeof(struct ip);
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m->m_len += sizeof(struct ip);
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m->m_pkthdr.len = m->m_len;
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m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
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nip = mtod(m, struct ip *);
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bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
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nip->ip_len = m->m_len;
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nip->ip_vhl = IP_VHL_BORING;
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nip->ip_p = IPPROTO_ICMP;
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nip->ip_tos = 0;
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icmp_reflect(m);
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freeit:
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m_freem(n);
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}
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static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
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static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
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static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
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/*
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* Process a received ICMP message.
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*/
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void
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icmp_input(m, hlen)
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register struct mbuf *m;
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int hlen;
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{
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register struct icmp *icp;
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register struct ip *ip = mtod(m, struct ip *);
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int icmplen = ip->ip_len;
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register int i;
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struct in_ifaddr *ia;
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void (*ctlfunc) __P((int, struct sockaddr *, void *));
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int code;
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/*
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* Locate icmp structure in mbuf, and check
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* that not corrupted and of at least minimum length.
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*/
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#ifdef ICMPPRINTFS
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if (icmpprintfs) {
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char buf[4 * sizeof "123"];
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strcpy(buf, inet_ntoa(ip->ip_src));
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printf("icmp_input from %s to %s, len %d\n",
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buf, inet_ntoa(ip->ip_dst), icmplen);
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}
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#endif
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if (icmplen < ICMP_MINLEN) {
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icmpstat.icps_tooshort++;
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goto freeit;
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}
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i = hlen + min(icmplen, ICMP_ADVLENMIN);
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if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
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icmpstat.icps_tooshort++;
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return;
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}
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ip = mtod(m, struct ip *);
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m->m_len -= hlen;
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m->m_data += hlen;
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icp = mtod(m, struct icmp *);
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if (in_cksum(m, icmplen)) {
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icmpstat.icps_checksum++;
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goto freeit;
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}
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m->m_len += hlen;
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m->m_data -= hlen;
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#ifdef ICMPPRINTFS
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if (icmpprintfs)
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printf("icmp_input, type %d code %d\n", icp->icmp_type,
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icp->icmp_code);
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#endif
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/*
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* Message type specific processing.
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*/
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if (icp->icmp_type > ICMP_MAXTYPE)
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goto raw;
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icmpstat.icps_inhist[icp->icmp_type]++;
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code = icp->icmp_code;
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switch (icp->icmp_type) {
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case ICMP_UNREACH:
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switch (code) {
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case ICMP_UNREACH_NET:
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case ICMP_UNREACH_HOST:
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case ICMP_UNREACH_PROTOCOL:
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case ICMP_UNREACH_PORT:
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case ICMP_UNREACH_SRCFAIL:
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code += PRC_UNREACH_NET;
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break;
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case ICMP_UNREACH_NEEDFRAG:
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code = PRC_MSGSIZE;
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break;
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case ICMP_UNREACH_NET_UNKNOWN:
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case ICMP_UNREACH_NET_PROHIB:
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case ICMP_UNREACH_TOSNET:
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code = PRC_UNREACH_NET;
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break;
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case ICMP_UNREACH_HOST_UNKNOWN:
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case ICMP_UNREACH_ISOLATED:
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case ICMP_UNREACH_HOST_PROHIB:
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case ICMP_UNREACH_TOSHOST:
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code = PRC_UNREACH_HOST;
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break;
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case ICMP_UNREACH_FILTER_PROHIB:
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case ICMP_UNREACH_HOST_PRECEDENCE:
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case ICMP_UNREACH_PRECEDENCE_CUTOFF:
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code = PRC_UNREACH_PORT;
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break;
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default:
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goto badcode;
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}
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goto deliver;
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case ICMP_TIMXCEED:
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if (code > 1)
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goto badcode;
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code += PRC_TIMXCEED_INTRANS;
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goto deliver;
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case ICMP_PARAMPROB:
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if (code > 1)
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goto badcode;
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code = PRC_PARAMPROB;
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goto deliver;
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case ICMP_SOURCEQUENCH:
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if (code)
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goto badcode;
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code = PRC_QUENCH;
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deliver:
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/*
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* Problem with datagram; advise higher level routines.
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*/
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if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
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IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
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icmpstat.icps_badlen++;
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goto freeit;
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}
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NTOHS(icp->icmp_ip.ip_len);
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/* Discard ICMP's in response to multicast packets */
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if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
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goto badcode;
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#ifdef ICMPPRINTFS
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if (icmpprintfs)
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printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
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#endif
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icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
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#if 1
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/*
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* MTU discovery:
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* If we got a needfrag and there is a host route to the
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* original destination, and the MTU is not locked, then
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* set the MTU in the route to the suggested new value
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* (if given) and then notify as usual. The ULPs will
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* notice that the MTU has changed and adapt accordingly.
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* If no new MTU was suggested, then we guess a new one
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* less than the current value. If the new MTU is
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* unreasonably small (arbitrarily set at 296), then
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* we reset the MTU to the interface value and enable the
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* lock bit, indicating that we are no longer doing MTU
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* discovery.
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*/
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if (code == PRC_MSGSIZE) {
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struct rtentry *rt;
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int mtu;
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rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
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RTF_CLONING | RTF_PRCLONING);
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if (rt && (rt->rt_flags & RTF_HOST)
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&& !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
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mtu = ntohs(icp->icmp_nextmtu);
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if (!mtu)
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mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
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1);
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#ifdef DEBUG_MTUDISC
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printf("MTU for %s reduced to %d\n",
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inet_ntoa(icmpsrc.sin_addr), mtu);
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#endif
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if (mtu < 296) {
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/* rt->rt_rmx.rmx_mtu =
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rt->rt_ifp->if_mtu; */
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rt->rt_rmx.rmx_locks |= RTV_MTU;
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} else if (rt->rt_rmx.rmx_mtu > mtu) {
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rt->rt_rmx.rmx_mtu = mtu;
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}
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}
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if (rt)
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RTFREE(rt);
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}
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#endif
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ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
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if (ctlfunc)
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(*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
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(void *)&icp->icmp_ip);
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break;
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badcode:
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icmpstat.icps_badcode++;
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break;
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case ICMP_ECHO:
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icp->icmp_type = ICMP_ECHOREPLY;
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goto reflect;
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case ICMP_TSTAMP:
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if (icmplen < ICMP_TSLEN) {
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icmpstat.icps_badlen++;
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break;
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}
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icp->icmp_type = ICMP_TSTAMPREPLY;
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icp->icmp_rtime = iptime();
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icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
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goto reflect;
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case ICMP_MASKREQ:
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#define satosin(sa) ((struct sockaddr_in *)(sa))
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if (icmpmaskrepl == 0)
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break;
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/*
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* We are not able to respond with all ones broadcast
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* unless we receive it over a point-to-point interface.
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*/
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if (icmplen < ICMP_MASKLEN)
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break;
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switch (ip->ip_dst.s_addr) {
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case INADDR_BROADCAST:
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case INADDR_ANY:
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icmpdst.sin_addr = ip->ip_src;
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break;
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default:
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icmpdst.sin_addr = ip->ip_dst;
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}
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ia = (struct in_ifaddr *)ifaof_ifpforaddr(
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(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
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if (ia == 0)
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break;
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if (ia->ia_ifp == 0)
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break;
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icp->icmp_type = ICMP_MASKREPLY;
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icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
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if (ip->ip_src.s_addr == 0) {
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if (ia->ia_ifp->if_flags & IFF_BROADCAST)
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ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
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else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
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ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
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}
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reflect:
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ip->ip_len += hlen; /* since ip_input deducts this */
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icmpstat.icps_reflect++;
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icmpstat.icps_outhist[icp->icmp_type]++;
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icmp_reflect(m);
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return;
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case ICMP_REDIRECT:
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if (code > 3)
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goto badcode;
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if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
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IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
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icmpstat.icps_badlen++;
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break;
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}
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/*
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* Short circuit routing redirects to force
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* immediate change in the kernel's routing
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* tables. The message is also handed to anyone
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* listening on a raw socket (e.g. the routing
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* daemon for use in updating its tables).
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*/
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icmpgw.sin_addr = ip->ip_src;
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icmpdst.sin_addr = icp->icmp_gwaddr;
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#ifdef ICMPPRINTFS
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if (icmpprintfs) {
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char buf[4 * sizeof "123"];
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strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
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printf("redirect dst %s to %s\n",
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buf, inet_ntoa(icp->icmp_gwaddr));
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}
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#endif
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icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
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rtredirect((struct sockaddr *)&icmpsrc,
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(struct sockaddr *)&icmpdst,
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(struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
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(struct sockaddr *)&icmpgw, (struct rtentry **)0);
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pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
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break;
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/*
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* No kernel processing for the following;
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* just fall through to send to raw listener.
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*/
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case ICMP_ECHOREPLY:
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case ICMP_ROUTERADVERT:
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case ICMP_ROUTERSOLICIT:
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case ICMP_TSTAMPREPLY:
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case ICMP_IREQREPLY:
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case ICMP_MASKREPLY:
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default:
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break;
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}
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raw:
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rip_input(m, hlen);
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return;
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freeit:
|
|
m_freem(m);
|
|
}
|
|
|
|
/*
|
|
* Reflect the ip packet back to the source
|
|
*/
|
|
static void
|
|
icmp_reflect(m)
|
|
struct mbuf *m;
|
|
{
|
|
register struct ip *ip = mtod(m, struct ip *);
|
|
register struct in_ifaddr *ia;
|
|
struct in_addr t;
|
|
struct mbuf *opts = 0;
|
|
int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
|
|
|
|
if (!in_canforward(ip->ip_src) &&
|
|
((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
|
|
(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
|
|
m_freem(m); /* Bad return address */
|
|
goto done; /* Ip_output() will check for broadcast */
|
|
}
|
|
t = ip->ip_dst;
|
|
ip->ip_dst = ip->ip_src;
|
|
/*
|
|
* If the incoming packet was addressed directly to us,
|
|
* use dst as the src for the reply. Otherwise (broadcast
|
|
* or anonymous), use the address which corresponds
|
|
* to the incoming interface.
|
|
*/
|
|
for (ia = in_ifaddrhead.tqh_first; ia; ia = ia->ia_link.tqe_next) {
|
|
if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
|
|
break;
|
|
if (ia->ia_ifp && (ia->ia_ifp->if_flags & IFF_BROADCAST) &&
|
|
t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
|
|
break;
|
|
}
|
|
icmpdst.sin_addr = t;
|
|
if ((ia == (struct in_ifaddr *)0) && m->m_pkthdr.rcvif)
|
|
ia = (struct in_ifaddr *)ifaof_ifpforaddr(
|
|
(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
|
|
/*
|
|
* The following happens if the packet was not addressed to us,
|
|
* and was received on an interface with no IP address.
|
|
*/
|
|
if (ia == (struct in_ifaddr *)0)
|
|
ia = in_ifaddrhead.tqh_first;
|
|
t = IA_SIN(ia)->sin_addr;
|
|
ip->ip_src = t;
|
|
ip->ip_ttl = MAXTTL;
|
|
|
|
if (optlen > 0) {
|
|
register u_char *cp;
|
|
int opt, cnt;
|
|
u_int len;
|
|
|
|
/*
|
|
* Retrieve any source routing from the incoming packet;
|
|
* add on any record-route or timestamp options.
|
|
*/
|
|
cp = (u_char *) (ip + 1);
|
|
if ((opts = ip_srcroute()) == 0 &&
|
|
(opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
|
|
opts->m_len = sizeof(struct in_addr);
|
|
mtod(opts, struct in_addr *)->s_addr = 0;
|
|
}
|
|
if (opts) {
|
|
#ifdef ICMPPRINTFS
|
|
if (icmpprintfs)
|
|
printf("icmp_reflect optlen %d rt %d => ",
|
|
optlen, opts->m_len);
|
|
#endif
|
|
for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
|
|
opt = cp[IPOPT_OPTVAL];
|
|
if (opt == IPOPT_EOL)
|
|
break;
|
|
if (opt == IPOPT_NOP)
|
|
len = 1;
|
|
else {
|
|
len = cp[IPOPT_OLEN];
|
|
if (len <= 0 || len > cnt)
|
|
break;
|
|
}
|
|
/*
|
|
* Should check for overflow, but it "can't happen"
|
|
*/
|
|
if (opt == IPOPT_RR || opt == IPOPT_TS ||
|
|
opt == IPOPT_SECURITY) {
|
|
bcopy((caddr_t)cp,
|
|
mtod(opts, caddr_t) + opts->m_len, len);
|
|
opts->m_len += len;
|
|
}
|
|
}
|
|
/* Terminate & pad, if necessary */
|
|
cnt = opts->m_len % 4;
|
|
if (cnt) {
|
|
for (; cnt < 4; cnt++) {
|
|
*(mtod(opts, caddr_t) + opts->m_len) =
|
|
IPOPT_EOL;
|
|
opts->m_len++;
|
|
}
|
|
}
|
|
#ifdef ICMPPRINTFS
|
|
if (icmpprintfs)
|
|
printf("%d\n", opts->m_len);
|
|
#endif
|
|
}
|
|
/*
|
|
* Now strip out original options by copying rest of first
|
|
* mbuf's data back, and adjust the IP length.
|
|
*/
|
|
ip->ip_len -= optlen;
|
|
ip->ip_vhl = IP_VHL_BORING;
|
|
m->m_len -= optlen;
|
|
if (m->m_flags & M_PKTHDR)
|
|
m->m_pkthdr.len -= optlen;
|
|
optlen += sizeof(struct ip);
|
|
bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
|
|
(unsigned)(m->m_len - sizeof(struct ip)));
|
|
}
|
|
m->m_flags &= ~(M_BCAST|M_MCAST);
|
|
icmp_send(m, opts);
|
|
done:
|
|
if (opts)
|
|
(void)m_free(opts);
|
|
}
|
|
|
|
/*
|
|
* Send an icmp packet back to the ip level,
|
|
* after supplying a checksum.
|
|
*/
|
|
static void
|
|
icmp_send(m, opts)
|
|
register struct mbuf *m;
|
|
struct mbuf *opts;
|
|
{
|
|
register struct ip *ip = mtod(m, struct ip *);
|
|
register int hlen;
|
|
register struct icmp *icp;
|
|
struct route ro;
|
|
|
|
hlen = IP_VHL_HL(ip->ip_vhl) << 2;
|
|
m->m_data += hlen;
|
|
m->m_len -= hlen;
|
|
icp = mtod(m, struct icmp *);
|
|
icp->icmp_cksum = 0;
|
|
icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
|
|
m->m_data -= hlen;
|
|
m->m_len += hlen;
|
|
#ifdef ICMPPRINTFS
|
|
if (icmpprintfs) {
|
|
char buf[4 * sizeof "123"];
|
|
strcpy(buf, inet_ntoa(ip->ip_dst));
|
|
printf("icmp_send dst %s src %s\n",
|
|
buf, inet_ntoa(ip->ip_src));
|
|
}
|
|
#endif
|
|
bzero(&ro, sizeof ro);
|
|
(void) ip_output(m, opts, &ro, 0, NULL);
|
|
if (ro.ro_rt)
|
|
RTFREE(ro.ro_rt);
|
|
}
|
|
|
|
n_time
|
|
iptime()
|
|
{
|
|
struct timeval atv;
|
|
u_long t;
|
|
|
|
microtime(&atv);
|
|
t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
|
|
return (htonl(t));
|
|
}
|
|
|
|
#if 1
|
|
/*
|
|
* Return the next larger or smaller MTU plateau (table from RFC 1191)
|
|
* given current value MTU. If DIR is less than zero, a larger plateau
|
|
* is returned; otherwise, a smaller value is returned.
|
|
*/
|
|
static int
|
|
ip_next_mtu(mtu, dir)
|
|
int mtu;
|
|
int dir;
|
|
{
|
|
static int mtutab[] = {
|
|
65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
|
|
68, 0
|
|
};
|
|
int i;
|
|
|
|
for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
|
|
if (mtu >= mtutab[i])
|
|
break;
|
|
}
|
|
|
|
if (dir < 0) {
|
|
if (i == 0) {
|
|
return 0;
|
|
} else {
|
|
return mtutab[i - 1];
|
|
}
|
|
} else {
|
|
if (mtutab[i] == 0) {
|
|
return 0;
|
|
} else if(mtu > mtutab[i]) {
|
|
return mtutab[i];
|
|
} else {
|
|
return mtutab[i + 1];
|
|
}
|
|
}
|
|
}
|
|
#endif
|