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      1 /*
      2  * Copyright (C) 2001 WIDE Project.  All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  * 3. Neither the name of the project nor the names of its contributors
     13  *    may be used to endorse or promote products derived from this software
     14  *    without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 #ifndef lint
     31 __RCSID("$NetBSD: print-mpls.c,v 1.10 2024/09/02 16:15:32 christos Exp $");
     32 #endif
     33 
     34 /* \summary: Multi-Protocol Label Switching (MPLS) printer */
     35 
     36 #include <config.h>
     37 
     38 #include "netdissect-stdinc.h"
     39 
     40 #define ND_LONGJMP_FROM_TCHECK
     41 #include "netdissect.h"
     42 #include "extract.h"
     43 #include "mpls.h"
     44 
     45 static const char *mpls_labelname[] = {
     46 /*0*/	"IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
     47 	"implicit NULL", "rsvd",
     48 /*5*/	"rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
     49 /*10*/	"rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
     50 /*15*/	"rsvd",
     51 };
     52 
     53 enum mpls_packet_type {
     54 	PT_UNKNOWN,
     55 	PT_IPV4,
     56 	PT_IPV6,
     57 	PT_OSI
     58 };
     59 
     60 /*
     61  * RFC3032: MPLS label stack encoding
     62  */
     63 void
     64 mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
     65 {
     66 	const u_char *p;
     67 	uint32_t label_entry;
     68 	uint16_t label_stack_depth = 0;
     69 	uint8_t first;
     70 	enum mpls_packet_type pt = PT_UNKNOWN;
     71 
     72 	ndo->ndo_protocol = "mpls";
     73 	p = bp;
     74 	nd_print_protocol_caps(ndo);
     75 	do {
     76 		if (length < sizeof(label_entry))
     77 			goto invalid;
     78 		label_entry = GET_BE_U_4(p);
     79 		ND_PRINT("%s(label %u",
     80 		       (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
     81 			MPLS_LABEL(label_entry));
     82 		label_stack_depth++;
     83 		if (ndo->ndo_vflag &&
     84 		    MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
     85 			ND_PRINT(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
     86 		ND_PRINT(", tc %u", MPLS_TC(label_entry));
     87 		if (MPLS_STACK(label_entry))
     88 			ND_PRINT(", [S]");
     89 		ND_PRINT(", ttl %u)", MPLS_TTL(label_entry));
     90 
     91 		p += sizeof(label_entry);
     92 		length -= sizeof(label_entry);
     93 	} while (!MPLS_STACK(label_entry));
     94 
     95 	/*
     96 	 * Try to figure out the packet type.
     97 	 */
     98 	switch (MPLS_LABEL(label_entry)) {
     99 
    100 	case 0:	/* IPv4 explicit NULL label */
    101 	case 3:	/* IPv4 implicit NULL label */
    102 		pt = PT_IPV4;
    103 		break;
    104 
    105 	case 2:	/* IPv6 explicit NULL label */
    106 		pt = PT_IPV6;
    107 		break;
    108 
    109 	default:
    110 		/*
    111 		 * Generally there's no indication of protocol in MPLS label
    112 		 * encoding.
    113 		 *
    114 		 * However, draft-hsmit-isis-aal5mux-00.txt describes a
    115 		 * technique for encapsulating IS-IS and IP traffic on the
    116 		 * same ATM virtual circuit; you look at the first payload
    117 		 * byte to determine the network layer protocol, based on
    118 		 * the fact that
    119 		 *
    120 		 *	1) the first byte of an IP header is 0x45-0x4f
    121 		 *	   for IPv4 and 0x60-0x6f for IPv6;
    122 		 *
    123 		 *	2) the first byte of an OSI CLNP packet is 0x81,
    124 		 *	   the first byte of an OSI ES-IS packet is 0x82,
    125 		 *	   and the first byte of an OSI IS-IS packet is
    126 		 *	   0x83;
    127 		 *
    128 		 * so the network layer protocol can be inferred from the
    129 		 * first byte of the packet, if the protocol is one of the
    130 		 * ones listed above.
    131 		 *
    132 		 * Cisco sends control-plane traffic MPLS-encapsulated in
    133 		 * this fashion.
    134 		 */
    135 		if (length < 1) {
    136 			/* nothing to print */
    137 			return;
    138 		}
    139 		first = GET_U_1(p);
    140 		pt =
    141 			(first >= 0x45 && first <= 0x4f) ? PT_IPV4 :
    142 			(first >= 0x60 && first <= 0x6f) ? PT_IPV6 :
    143 			(first >= 0x81 && first <= 0x83) ? PT_OSI :
    144 			/* ok bail out - we did not figure out what it is*/
    145 			PT_UNKNOWN;
    146 	}
    147 
    148 	/*
    149 	 * Print the payload.
    150 	 */
    151 	switch (pt) {
    152 	case PT_UNKNOWN:
    153 		if (!ndo->ndo_suppress_default_print)
    154 			ND_DEFAULTPRINT(p, length);
    155 		break;
    156 
    157 	case PT_IPV4:
    158 		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
    159 		ip_print(ndo, p, length);
    160 		break;
    161 
    162 	case PT_IPV6:
    163 		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
    164 		ip6_print(ndo, p, length);
    165 		break;
    166 
    167 	case PT_OSI:
    168 		ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
    169 		isoclns_print(ndo, p, length);
    170 		break;
    171 	}
    172 	return;
    173 
    174 invalid:
    175 	nd_print_invalid(ndo);
    176 	ND_TCHECK_LEN(p, length);
    177 }
    178