/*
* Copyright (C) 2001 WIDE Project.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-mpls.c,v 1.10 2024/09/02 16:15:32 christos Exp $");
#endif

/* \summary: Multi-Protocol Label Switching (MPLS) printer */

#include <config.h>

#include "netdissect-stdinc.h"

#define ND_LONGJMP_FROM_TCHECK
#include "netdissect.h"
#include "extract.h"
#include "mpls.h"

static const char *mpls_labelname[] = {
/*0*/   "IPv4 explicit NULL", "router alert", "IPv6 explicit NULL",
       "implicit NULL", "rsvd",
/*5*/   "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
/*10*/  "rsvd", "rsvd", "rsvd", "rsvd", "rsvd",
/*15*/  "rsvd",
};

enum mpls_packet_type {
       PT_UNKNOWN,
       PT_IPV4,
       PT_IPV6,
       PT_OSI
};

/*
* RFC3032: MPLS label stack encoding
*/
void
mpls_print(netdissect_options *ndo, const u_char *bp, u_int length)
{
       const u_char *p;
       uint32_t label_entry;
       uint16_t label_stack_depth = 0;
       uint8_t first;
       enum mpls_packet_type pt = PT_UNKNOWN;

       ndo->ndo_protocol = "mpls";
       p = bp;
       nd_print_protocol_caps(ndo);
       do {
               if (length < sizeof(label_entry))
                       goto invalid;
               label_entry = GET_BE_U_4(p);
               ND_PRINT("%s(label %u",
                      (label_stack_depth && ndo->ndo_vflag) ? "\n\t" : " ",
                       MPLS_LABEL(label_entry));
               label_stack_depth++;
               if (ndo->ndo_vflag &&
                   MPLS_LABEL(label_entry) < sizeof(mpls_labelname) / sizeof(mpls_labelname[0]))
                       ND_PRINT(" (%s)", mpls_labelname[MPLS_LABEL(label_entry)]);
               ND_PRINT(", tc %u", MPLS_TC(label_entry));
               if (MPLS_STACK(label_entry))
                       ND_PRINT(", [S]");
               ND_PRINT(", ttl %u)", MPLS_TTL(label_entry));

               p += sizeof(label_entry);
               length -= sizeof(label_entry);
       } while (!MPLS_STACK(label_entry));

       /*
        * Try to figure out the packet type.
        */
       switch (MPLS_LABEL(label_entry)) {

       case 0: /* IPv4 explicit NULL label */
       case 3: /* IPv4 implicit NULL label */
               pt = PT_IPV4;
               break;

       case 2: /* IPv6 explicit NULL label */
               pt = PT_IPV6;
               break;

       default:
               /*
                * Generally there's no indication of protocol in MPLS label
                * encoding.
                *
                * However, draft-hsmit-isis-aal5mux-00.txt describes a
                * technique for encapsulating IS-IS and IP traffic on the
                * same ATM virtual circuit; you look at the first payload
                * byte to determine the network layer protocol, based on
                * the fact that
                *
                *      1) the first byte of an IP header is 0x45-0x4f
                *         for IPv4 and 0x60-0x6f for IPv6;
                *
                *      2) the first byte of an OSI CLNP packet is 0x81,
                *         the first byte of an OSI ES-IS packet is 0x82,
                *         and the first byte of an OSI IS-IS packet is
                *         0x83;
                *
                * so the network layer protocol can be inferred from the
                * first byte of the packet, if the protocol is one of the
                * ones listed above.
                *
                * Cisco sends control-plane traffic MPLS-encapsulated in
                * this fashion.
                */
               if (length < 1) {
                       /* nothing to print */
                       return;
               }
               first = GET_U_1(p);
               pt =
                       (first >= 0x45 && first <= 0x4f) ? PT_IPV4 :
                       (first >= 0x60 && first <= 0x6f) ? PT_IPV6 :
                       (first >= 0x81 && first <= 0x83) ? PT_OSI :
                       /* ok bail out - we did not figure out what it is*/
                       PT_UNKNOWN;
       }

       /*
        * Print the payload.
        */
       switch (pt) {
       case PT_UNKNOWN:
               if (!ndo->ndo_suppress_default_print)
                       ND_DEFAULTPRINT(p, length);
               break;

       case PT_IPV4:
               ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
               ip_print(ndo, p, length);
               break;

       case PT_IPV6:
               ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
               ip6_print(ndo, p, length);
               break;

       case PT_OSI:
               ND_PRINT(ndo->ndo_vflag ? "\n\t" : " ");
               isoclns_print(ndo, p, length);
               break;
       }
       return;

invalid:
       nd_print_invalid(ndo);
       ND_TCHECK_LEN(p, length);
}