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mpls_ttl.c revision 1.10
      1  1.10    maxv /*	$NetBSD: mpls_ttl.c,v 1.10 2018/01/19 10:54:31 maxv Exp $ */
      2   1.1  kefren 
      3   1.9    maxv /*
      4   1.1  kefren  * Copyright (c) 2010 The NetBSD Foundation, Inc.
      5   1.1  kefren  * All rights reserved.
      6   1.1  kefren  *
      7   1.1  kefren  * This code is derived from software contributed to The NetBSD Foundation
      8   1.1  kefren  * by Public Access Networks Corporation ("Panix").  It was developed under
      9   1.1  kefren  * contract to Panix by Eric Haszlakiewicz and Thor Lancelot Simon.
     10   1.1  kefren  *
     11   1.1  kefren  * This code is derived from software contributed to The NetBSD Foundation
     12   1.1  kefren  * by Jason R. Thorpe of Zembu Labs, Inc.
     13   1.1  kefren  *
     14   1.1  kefren  * This code is derived from software contributed to The NetBSD Foundation
     15   1.1  kefren  * by Mihai Chelaru <kefren (at) NetBSD.org>
     16   1.1  kefren  *
     17   1.1  kefren  * Redistribution and use in source and binary forms, with or without
     18   1.1  kefren  * modification, are permitted provided that the following conditions
     19   1.1  kefren  * are met:
     20   1.1  kefren  * 1. Redistributions of source code must retain the above copyright
     21   1.1  kefren  *    notice, this list of conditions and the following disclaimer.
     22   1.1  kefren  * 2. Redistributions in binary form must reproduce the above copyright
     23   1.1  kefren  *    notice, this list of conditions and the following disclaimer in the
     24   1.1  kefren  *    documentation and/or other materials provided with the distribution.
     25   1.1  kefren  *
     26   1.1  kefren  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27   1.1  kefren  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28   1.1  kefren  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29   1.1  kefren  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30   1.1  kefren  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31   1.1  kefren  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32   1.1  kefren  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33   1.1  kefren  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34   1.1  kefren  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35   1.1  kefren  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36   1.1  kefren  * POSSIBILITY OF SUCH DAMAGE.
     37   1.1  kefren  */
     38   1.1  kefren 
     39   1.1  kefren /*
     40  1.10    maxv  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
     41  1.10    maxv  * All rights reserved.
     42  1.10    maxv  *
     43  1.10    maxv  * Redistribution and use in source and binary forms, with or without
     44  1.10    maxv  * modification, are permitted provided that the following conditions
     45  1.10    maxv  * are met:
     46  1.10    maxv  * 1. Redistributions of source code must retain the above copyright
     47  1.10    maxv  *    notice, this list of conditions and the following disclaimer.
     48  1.10    maxv  * 2. Redistributions in binary form must reproduce the above copyright
     49  1.10    maxv  *    notice, this list of conditions and the following disclaimer in the
     50  1.10    maxv  *    documentation and/or other materials provided with the distribution.
     51  1.10    maxv  * 3. Neither the name of the project nor the names of its contributors
     52  1.10    maxv  *    may be used to endorse or promote products derived from this software
     53  1.10    maxv  *    without specific prior written permission.
     54  1.10    maxv  *
     55  1.10    maxv  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     56  1.10    maxv  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     57  1.10    maxv  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     58  1.10    maxv  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     59  1.10    maxv  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     60  1.10    maxv  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     61  1.10    maxv  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     62  1.10    maxv  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     63  1.10    maxv  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     64  1.10    maxv  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     65  1.10    maxv  * SUCH DAMAGE.
     66  1.10    maxv  */
     67  1.10    maxv 
     68  1.10    maxv /*
     69   1.1  kefren  * Copyright (c) 1982, 1986, 1988, 1993
     70   1.1  kefren  *      The Regents of the University of California.  All rights reserved.
     71   1.1  kefren  *
     72   1.1  kefren  * Redistribution and use in source and binary forms, with or without
     73   1.1  kefren  * modification, are permitted provided that the following conditions
     74   1.1  kefren  * are met:
     75   1.1  kefren  * 1. Redistributions of source code must retain the above copyright
     76   1.1  kefren  *    notice, this list of conditions and the following disclaimer.
     77   1.1  kefren  * 2. Redistributions in binary form must reproduce the above copyright
     78   1.1  kefren  *    notice, this list of conditions and the following disclaimer in the
     79   1.1  kefren  *    documentation and/or other materials provided with the distribution.
     80   1.1  kefren  * 3. Neither the name of the University nor the names of its contributors
     81   1.1  kefren  *    may be used to endorse or promote products derived from this software
     82   1.1  kefren  *    without specific prior written permission.
     83   1.1  kefren  *
     84   1.1  kefren  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     85   1.1  kefren  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     86   1.1  kefren  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     87   1.1  kefren  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     88   1.1  kefren  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     89   1.1  kefren  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     90   1.1  kefren  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     91   1.1  kefren  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     92   1.1  kefren  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     93   1.1  kefren  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     94   1.1  kefren  * SUCH DAMAGE.
     95   1.1  kefren  *
     96   1.1  kefren  *      @(#)ip_icmp.c   8.2 (Berkeley) 1/4/94
     97   1.1  kefren  */
     98   1.1  kefren 
     99   1.1  kefren #include <sys/cdefs.h>
    100  1.10    maxv __KERNEL_RCSID(0, "$NetBSD: mpls_ttl.c,v 1.10 2018/01/19 10:54:31 maxv Exp $");
    101   1.1  kefren 
    102   1.5   pooka #ifdef _KERNEL_OPT
    103   1.1  kefren #include "opt_inet.h"
    104   1.1  kefren #include "opt_mpls.h"
    105   1.5   pooka #endif
    106   1.1  kefren 
    107   1.1  kefren #include <sys/param.h>
    108   1.1  kefren #include <sys/malloc.h>
    109   1.1  kefren #include <sys/mbuf.h>
    110   1.1  kefren #include <sys/errno.h>
    111   1.1  kefren #include <sys/socket.h>
    112   1.1  kefren #include <sys/systm.h>
    113   1.1  kefren 
    114   1.1  kefren #include <net/if.h>
    115   1.1  kefren #include <net/if_dl.h>
    116   1.1  kefren 
    117   1.1  kefren #include <netinet/in.h>
    118   1.1  kefren #include <netinet/in_systm.h>
    119   1.1  kefren #include <netinet/ip.h>
    120   1.1  kefren #include <netinet/ip_icmp.h>
    121   1.1  kefren #include <netinet/icmp_private.h>
    122   1.1  kefren #include <netinet/icmp_var.h>
    123   1.1  kefren 
    124   1.1  kefren #include <netmpls/mpls.h>
    125   1.1  kefren #include <netmpls/mpls_var.h>
    126   1.1  kefren 
    127   1.1  kefren #ifdef INET
    128   1.1  kefren 
    129   1.1  kefren /* in netinet/ip_icmp.c */
    130   1.1  kefren extern int icmpreturndatabytes;
    131   1.1  kefren 
    132   1.1  kefren /* ICMP Extensions */
    133   1.1  kefren #define MPLS_STACK_ENTRY_CLASS 1
    134   1.1  kefren #define MPLS_STACK_ENTRY_C_TYPE 1
    135   1.1  kefren 
    136   1.1  kefren struct mpls_extension {
    137  1.10    maxv 	struct icmp_ext_hdr cmn_hdr;
    138   1.1  kefren 	struct icmp_ext_obj_hdr obj_hdr;
    139   1.1  kefren 	union mpls_shim ms;
    140   1.1  kefren } __packed;
    141   1.1  kefren 
    142   1.3  kefren static void mpls_icmp_error(struct mbuf *, int, int, n_long, int,
    143   1.9    maxv     union mpls_shim *);
    144   1.9    maxv static struct mbuf *ip4_check(struct mbuf *);
    145   1.1  kefren 
    146   1.1  kefren /*
    147  1.10    maxv  * Send an ICMP Extended error message. References: RFC4884 and RFC4950.
    148  1.10    maxv  *
    149   1.1  kefren  * This should be in sync with icmp_error() in sys/netinet/ip_icmp.c
    150   1.4  kefren  * XXX: is called only for ICMP_TIMXCEED_INTRANS but code is too general
    151   1.1  kefren  */
    152   1.1  kefren static void
    153   1.1  kefren mpls_icmp_error(struct mbuf *n, int type, int code, n_long dest,
    154   1.1  kefren     int destmtu, union mpls_shim *shim)
    155   1.1  kefren {
    156   1.2  kefren 	struct ip *oip = mtod(n, struct ip *), *nip;
    157   1.2  kefren 	unsigned oiplen = oip->ip_hl << 2;
    158   1.2  kefren 	struct icmp *icp;
    159   1.2  kefren 	struct mbuf *m;
    160   1.2  kefren 	unsigned icmplen, mblen, packetlen;
    161   1.1  kefren 	struct mpls_extension mpls_icmp_ext;
    162   1.9    maxv 
    163   1.1  kefren 	memset(&mpls_icmp_ext, 0, sizeof(mpls_icmp_ext));
    164   1.1  kefren 	mpls_icmp_ext.cmn_hdr.version = ICMP_EXT_VERSION;
    165   1.1  kefren 	mpls_icmp_ext.cmn_hdr.checksum = 0;
    166   1.1  kefren 
    167   1.9    maxv 	mpls_icmp_ext.obj_hdr.length = htons(sizeof(union mpls_shim) +
    168   1.9    maxv 	    sizeof(struct icmp_ext_obj_hdr));
    169   1.1  kefren 	mpls_icmp_ext.obj_hdr.class_num = MPLS_STACK_ENTRY_CLASS;
    170   1.1  kefren 	mpls_icmp_ext.obj_hdr.c_type = MPLS_STACK_ENTRY_C_TYPE;
    171   1.1  kefren 
    172   1.1  kefren 	mpls_icmp_ext.ms.s_addr = shim->s_addr;
    173   1.1  kefren 
    174   1.1  kefren #ifdef ICMPPRINTFS
    175   1.1  kefren 	if (icmpprintfs)
    176   1.1  kefren 		printf("mpls_icmp_error(%p, type:%d, code:%d)\n", oip, type,
    177   1.1  kefren 			code);
    178   1.1  kefren #endif
    179   1.1  kefren 	if (type != ICMP_REDIRECT)
    180   1.1  kefren 		ICMP_STATINC(ICMP_STAT_ERROR);
    181  1.10    maxv 
    182   1.1  kefren 	/*
    183   1.1  kefren 	 * Don't send error if the original packet was encrypted.
    184   1.1  kefren 	 * Don't send error if not the first fragment of message.
    185   1.1  kefren 	 * Don't error if the old packet protocol was ICMP
    186   1.1  kefren 	 * error message, only known informational types.
    187   1.1  kefren 	 */
    188   1.1  kefren 	if (n->m_flags & M_DECRYPTED)
    189   1.1  kefren 		goto freeit;
    190   1.1  kefren 	if (oip->ip_off &~ htons(IP_MF|IP_DF))
    191   1.1  kefren 		goto freeit;
    192   1.1  kefren 	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
    193   1.1  kefren 	    n->m_len >= oiplen + ICMP_MINLEN &&
    194   1.1  kefren 	    !ICMP_INFOTYPE(((struct icmp *)((char *)oip + oiplen))->icmp_type))
    195   1.1  kefren 	{
    196   1.1  kefren 		ICMP_STATINC(ICMP_STAT_OLDICMP);
    197   1.1  kefren 		goto freeit;
    198   1.1  kefren 	}
    199  1.10    maxv 
    200   1.1  kefren 	/* Don't send error in response to a multicast or broadcast packet */
    201   1.1  kefren 	if (n->m_flags & (M_BCAST|M_MCAST))
    202   1.1  kefren 		goto freeit;
    203   1.1  kefren 
    204   1.1  kefren 	/*
    205   1.1  kefren 	 * First, do a rate limitation check.
    206   1.1  kefren 	 */
    207   1.1  kefren 	if (icmp_ratelimit(&oip->ip_src, type, code))
    208   1.1  kefren 		/* XXX stats */
    209   1.1  kefren 		goto freeit;
    210   1.1  kefren 
    211   1.1  kefren 	/*
    212   1.1  kefren 	 * Now, formulate icmp message
    213   1.1  kefren 	 */
    214   1.1  kefren 	icmplen = min(ICMP_EXT_OFFSET, ntohs(oip->ip_len));
    215  1.10    maxv 
    216   1.1  kefren 	/*
    217   1.1  kefren 	 * Defend against mbuf chains shorter than oip->ip_len - oiplen:
    218   1.1  kefren 	 */
    219   1.1  kefren 	mblen = 0;
    220   1.1  kefren 	for (m = n; m && (mblen < icmplen); m = m->m_next)
    221   1.1  kefren 		mblen += m->m_len;
    222   1.1  kefren 	icmplen = min(mblen, icmplen);
    223   1.1  kefren 
    224   1.4  kefren 	packetlen = sizeof(struct ip) + offsetof(struct icmp, icmp_ip) +
    225   1.4  kefren 	    ICMP_EXT_OFFSET + sizeof(mpls_icmp_ext);
    226   1.2  kefren 
    227   1.1  kefren 	/*
    228   1.1  kefren 	 * As we are not required to return everything we have,
    229   1.1  kefren 	 * we return whatever we can return at ease.
    230   1.1  kefren 	 *
    231   1.1  kefren 	 * Note that ICMP datagrams longer than 576 octets are out of spec
    232   1.1  kefren 	 * according to RFC1812; the limit on icmpreturndatabytes below in
    233   1.1  kefren 	 * icmp_sysctl will keep things below that limit.
    234   1.1  kefren 	 */
    235   1.1  kefren 
    236  1.10    maxv 	KASSERT(packetlen <= MCLBYTES);
    237   1.1  kefren 
    238   1.1  kefren 	m = m_gethdr(M_DONTWAIT, MT_HEADER);
    239   1.2  kefren 	if (m && (packetlen > MHLEN)) {
    240   1.1  kefren 		MCLGET(m, M_DONTWAIT);
    241   1.1  kefren 		if ((m->m_flags & M_EXT) == 0) {
    242   1.1  kefren 			m_freem(m);
    243   1.1  kefren 			m = NULL;
    244   1.1  kefren 		}
    245   1.1  kefren 	}
    246   1.1  kefren 	if (m == NULL)
    247   1.1  kefren 		goto freeit;
    248  1.10    maxv 
    249   1.1  kefren 	MCLAIM(m, n->m_owner);
    250   1.2  kefren 	m->m_len = packetlen;
    251   1.1  kefren 	if ((m->m_flags & M_EXT) == 0)
    252   1.1  kefren 		MH_ALIGN(m, m->m_len);
    253   1.4  kefren 	m->m_data += sizeof(struct ip);
    254   1.4  kefren 	m->m_len -= sizeof(struct ip);
    255   1.4  kefren 
    256   1.1  kefren 	icp = mtod(m, struct icmp *);
    257   1.1  kefren 	if ((u_int)type > ICMP_MAXTYPE)
    258   1.4  kefren 		panic("icmp error (mpls_ttl)");
    259   1.1  kefren 	ICMP_STATINC(ICMP_STAT_OUTHIST + type);
    260   1.1  kefren 	icp->icmp_type = type;
    261   1.1  kefren 	if (type == ICMP_REDIRECT)
    262   1.1  kefren 		icp->icmp_gwaddr.s_addr = dest;
    263   1.1  kefren 	else {
    264   1.1  kefren 		icp->icmp_void = 0;
    265   1.1  kefren 		/*
    266   1.1  kefren 		 * The following assignments assume an overlay with the
    267   1.1  kefren 		 * zeroed icmp_void field.
    268   1.1  kefren 		 */
    269   1.1  kefren 		if (type == ICMP_PARAMPROB) {
    270   1.1  kefren 			icp->icmp_pptr = code;
    271   1.1  kefren 			code = 0;
    272   1.1  kefren 		} else if (type == ICMP_UNREACH &&
    273   1.1  kefren 		    code == ICMP_UNREACH_NEEDFRAG && destmtu)
    274   1.1  kefren 			icp->icmp_nextmtu = htons(destmtu);
    275   1.1  kefren 	}
    276   1.1  kefren 
    277   1.1  kefren 	icp->icmp_code = code;
    278   1.2  kefren 
    279   1.2  kefren 	memset(&icp->icmp_ip, 0, ICMP_EXT_OFFSET);
    280   1.1  kefren 	m_copydata(n, 0, icmplen, (char *)&icp->icmp_ip);
    281   1.1  kefren 
    282   1.2  kefren 	/* Append the extension structure */
    283   1.2  kefren 	memcpy(((char*)&icp->icmp_ip) + ICMP_EXT_OFFSET,
    284   1.1  kefren 	    &mpls_icmp_ext, sizeof(mpls_icmp_ext));
    285   1.1  kefren 
    286   1.1  kefren 	/*
    287   1.1  kefren 	 * Now, copy old ip header (without options)
    288   1.1  kefren 	 * in front of icmp message.
    289   1.9    maxv 	 */
    290   1.2  kefren 	if ((m->m_flags & M_EXT) == 0 &&
    291   1.2  kefren 	    m->m_data - sizeof(struct ip) < m->m_pktdat)
    292   1.2  kefren 		panic("icmp len");
    293   1.1  kefren 	m->m_data -= sizeof(struct ip);
    294   1.1  kefren 	m->m_len += sizeof(struct ip);
    295   1.1  kefren 	m->m_pkthdr.len = m->m_len;
    296   1.8   ozaki 	m_copy_rcvif(m, n);
    297   1.1  kefren 	nip = mtod(m, struct ip *);
    298   1.1  kefren 	/* ip_v set in ip_output */
    299   1.1  kefren 	nip->ip_hl = sizeof(struct ip) >> 2;
    300   1.1  kefren 	nip->ip_tos = 0;
    301   1.1  kefren 	nip->ip_len = htons(m->m_len);
    302   1.1  kefren 	/* ip_id set in ip_output */
    303   1.1  kefren 	nip->ip_off = htons(0);
    304   1.1  kefren 	/* ip_ttl set in icmp_reflect */
    305   1.1  kefren 	nip->ip_p = IPPROTO_ICMP;
    306   1.1  kefren 	nip->ip_src = oip->ip_src;
    307   1.1  kefren 	nip->ip_dst = oip->ip_dst;
    308   1.1  kefren 	icmp_reflect(m);
    309   1.1  kefren 
    310   1.1  kefren freeit:
    311   1.1  kefren 	m_freem(n);
    312   1.1  kefren }
    313   1.1  kefren 
    314   1.9    maxv static struct mbuf *
    315   1.3  kefren ip4_check(struct mbuf *m)
    316   1.3  kefren {
    317   1.3  kefren 	struct ip *iph;
    318   1.3  kefren 	int hlen, len;
    319   1.3  kefren 
    320   1.3  kefren 	if (m->m_len < sizeof(struct ip) &&
    321   1.3  kefren 	    (m = m_pullup(m, sizeof(struct ip))) == NULL)
    322   1.9    maxv 		return NULL;
    323   1.3  kefren 
    324   1.3  kefren 	iph = mtod(m, struct ip *);
    325   1.3  kefren 
    326   1.3  kefren 	if (iph->ip_v != IPVERSION)
    327   1.3  kefren 		goto freeit;
    328   1.3  kefren 	hlen = iph->ip_hl << 2;
    329   1.3  kefren 	if (hlen < sizeof(struct ip))
    330   1.3  kefren 		goto freeit;
    331   1.3  kefren 	if (hlen > m->m_len) {
    332   1.3  kefren 		if ((m = m_pullup(m, hlen)) == NULL)
    333   1.9    maxv 			return NULL;
    334   1.3  kefren 		iph = mtod(m, struct ip *);
    335   1.3  kefren 	}
    336  1.10    maxv 
    337  1.10    maxv 	/*
    338  1.10    maxv 	 * RFC1122: packets with a multicast source address are
    339  1.10    maxv 	 * not allowed.
    340  1.10    maxv 	 * RFC1122: 127/8 must not appear on wire.
    341  1.10    maxv 	 */
    342   1.3  kefren 	if (IN_MULTICAST(iph->ip_src.s_addr) ||
    343   1.3  kefren 	    (ntohl(iph->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
    344   1.3  kefren 	    (ntohl(iph->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
    345   1.3  kefren 	    in_cksum(m, hlen) != 0)
    346   1.3  kefren 		goto freeit;
    347   1.3  kefren 
    348   1.3  kefren 	len = ntohs(iph->ip_len);
    349   1.3  kefren 	if (len < hlen || m->m_pkthdr.len < len)
    350   1.3  kefren 		goto freeit;
    351   1.3  kefren 
    352   1.9    maxv 	return m;
    353   1.9    maxv 
    354   1.3  kefren freeit:
    355   1.3  kefren 	m_freem(m);
    356   1.9    maxv 	return NULL;
    357   1.3  kefren }
    358   1.1  kefren #endif	/* INET */
    359   1.1  kefren 
    360   1.1  kefren struct mbuf *
    361   1.1  kefren mpls_ttl_dec(struct mbuf *m)
    362   1.1  kefren {
    363   1.1  kefren 	union mpls_shim *mshim;
    364   1.1  kefren #ifdef INET
    365  1.10    maxv 	union mpls_shim top_shim, bos_shim;
    366   1.1  kefren #endif
    367   1.1  kefren 
    368   1.4  kefren 	if (__predict_false(m->m_len < sizeof(union mpls_shim) &&
    369   1.4  kefren 	    (m = m_pullup(m, sizeof(union mpls_shim))) == NULL))
    370   1.1  kefren 		return NULL;
    371   1.1  kefren 	mshim = mtod(m, union mpls_shim *);
    372   1.1  kefren 	mshim->s_addr = ntohl(mshim->s_addr);
    373   1.1  kefren 	mshim->shim.ttl--;
    374   1.1  kefren 
    375   1.1  kefren 	if (mshim->shim.ttl == 0) {
    376   1.1  kefren 		if (!mpls_icmp_respond) {
    377   1.1  kefren 			m_freem(m);
    378   1.1  kefren 			return NULL;
    379   1.1  kefren 		}
    380   1.1  kefren 
    381   1.1  kefren #ifdef INET
    382   1.1  kefren 		/*
    383   1.9    maxv 		 * Shim ttl exceeded. Send back ICMP type 11 code 0.
    384   1.1  kefren 		 */
    385  1.10    maxv 		bos_shim.s_addr = mshim->s_addr;
    386   1.2  kefren 		top_shim.s_addr = htonl(mshim->s_addr);
    387   1.1  kefren 		m_adj(m, sizeof(union mpls_shim));
    388   1.1  kefren 
    389   1.1  kefren 		/* Goto BOS */
    390  1.10    maxv 		while (bos_shim.shim.bos == 0) {
    391   1.1  kefren 			if (m->m_len < sizeof(union mpls_shim) &&
    392   1.1  kefren 			    (m = m_pullup(m, sizeof(union mpls_shim))) == NULL) {
    393   1.1  kefren 				m_freem(m);
    394   1.1  kefren 				return NULL;
    395   1.1  kefren 			}
    396  1.10    maxv 			bos_shim.s_addr = ntohl(mtod(m, union mpls_shim *)->s_addr);
    397   1.1  kefren 			m_adj(m, sizeof(union mpls_shim));
    398   1.1  kefren 		}
    399   1.9    maxv 
    400   1.9    maxv 		if ((m = ip4_check(m)) != NULL)
    401   1.3  kefren 			mpls_icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
    402   1.3  kefren 			    0, 0, &top_shim);
    403   1.2  kefren #else
    404   1.2  kefren 		m_freem(m);
    405   1.1  kefren #endif
    406   1.1  kefren 		return NULL;
    407   1.1  kefren 	}
    408   1.1  kefren 
    409   1.1  kefren 	mshim->s_addr = htonl(mshim->s_addr);
    410   1.1  kefren 
    411   1.1  kefren 	return m;
    412   1.1  kefren }
    413