/* Copyright (c) 2015, bugyo
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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-nsh.c,v 1.5 2024/09/02 16:15:32 christos Exp $");
#endif

/* \summary: Network Service Header (NSH) printer */

/* specification: RFC 8300 */

#include <config.h>

#include "netdissect-stdinc.h"

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

static const struct tok nsh_flags [] = {
   { 0x2, "O" },
   { 0, NULL }
};

/*
*    0                   1                   2                   3
*    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
*   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*   |Ver|O|U|    TTL    |   Length  |U|U|U|U|MD Type| Next Protocol |
*   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
#define NSH_BASE_HDR_LEN 4
#define NSH_VER(x)       (((x) & 0xc0000000) >> 30)
#define NSH_FLAGS(x)     (((x) & 0x30000000) >> 28)
#define NSH_TTL(x)       (((x) & 0x0fc00000) >> 22)
#define NSH_LENGTH(x)    (((x) & 0x003f0000) >> 16)
#define NSH_MD_TYPE(x)   (((x) & 0x00000f00) >>  8)
#define NSH_NEXT_PROT(x) (((x) & 0x000000ff) >>  0)

#define NSH_SERVICE_PATH_HDR_LEN 4
#define NSH_HDR_WORD_SIZE 4U

#define MD_RSV   0x00
#define MD_TYPE1 0x01
#define MD_TYPE2 0x02
#define MD_EXP   0x0F
static const struct tok md_str[] = {
   { MD_RSV,   "reserved"     },
   { MD_TYPE1, "1"            },
   { MD_TYPE2, "2"            },
   { MD_EXP,   "experimental" },
   { 0, NULL }
};

#define NP_IPV4 0x01
#define NP_IPV6 0x02
#define NP_ETH  0x03
#define NP_NSH  0x04
#define NP_MPLS 0x05
#define NP_EXP1 0xFE
#define NP_EXP2 0xFF
static const struct tok np_str[] = {
   { NP_IPV4, "IPv4"         },
   { NP_IPV6, "IPv6"         },
   { NP_ETH,  "Ethernet"     },
   { NP_NSH,  "NSH"          },
   { NP_MPLS, "MPLS"         },
   { NP_EXP1, "Experiment 1" },
   { NP_EXP2, "Experiment 2" },
   { 0, NULL }
};

void
nsh_print(netdissect_options *ndo, const u_char *bp, u_int len)
{
   uint32_t basehdr;
   u_int ver, length, md_type;
   uint8_t next_protocol;
   u_char past_headers = 0;
   u_int next_len;

   ndo->ndo_protocol = "nsh";
   /*
    *    0                   1                   2                   3
    *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    *   |                Base Header                                    |
    *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    *   |                Service Path Header                            |
    *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    *   |                                                               |
    *   ~                Context Header(s)                              ~
    *   |                                                               |
    *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    */

   /* print Base Header and Service Path Header */
   if (len < NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN) {
       ND_PRINT(" (packet length %u < %u)",
                len, NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN);
       goto invalid;
   }

   basehdr = GET_BE_U_4(bp);
   bp += 4;
   ver = NSH_VER(basehdr);
   length = NSH_LENGTH(basehdr);
   md_type = NSH_MD_TYPE(basehdr);
   next_protocol = NSH_NEXT_PROT(basehdr);

   ND_PRINT("NSH, ");
   if (ndo->ndo_vflag > 1) {
       ND_PRINT("ver %u, ", ver);
   }
   if (ver != 0)
       return;
   ND_PRINT("flags [%s], ",
            bittok2str_nosep(nsh_flags, "none", NSH_FLAGS(basehdr)));
   if (ndo->ndo_vflag > 2) {
       ND_PRINT("TTL %u, ", NSH_TTL(basehdr));
       ND_PRINT("length %u, ", length);
       ND_PRINT("md type %s, ", tok2str(md_str, "unknown (0x%02x)", md_type));
   }
   if (ndo->ndo_vflag > 1) {
       ND_PRINT("next-protocol %s, ",
                tok2str(np_str, "unknown (0x%02x)", next_protocol));
   }

   /* Make sure we have all the headers */
   if (len < length * NSH_HDR_WORD_SIZE) {
       ND_PRINT(" (too many headers for packet length %u)", len);
       goto invalid;
   }

   /*
    *    0                   1                   2                   3
    *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    *   |          Service Path Identifier (SPI)        | Service Index |
    *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    *
    */
   ND_PRINT("service-path-id 0x%06x, ", GET_BE_U_3(bp));
   bp += 3;
   ND_PRINT("service-index 0x%x", GET_U_1(bp));
   bp += 1;

   /*
    * length includes the lengths of the Base and Service Path headers.
    * That means it must be at least 2.
    */
   if (length < 2) {
       ND_PRINT(" (less than two headers)");
       goto invalid;
   }

   /*
    * Print, or skip, the Context Headers.
    * (length - 2) is the length of those headers.
    */
   if (ndo->ndo_vflag > 2) {
       u_int n;

       if (md_type == MD_TYPE1) {
           if (length != 6) {
               ND_PRINT(" (length for the MD type)");
               goto invalid;
           }
           for (n = 0; n < length - 2; n++) {
               ND_PRINT("\n        Context[%02u]: 0x%08x", n, GET_BE_U_4(bp));
               bp += NSH_HDR_WORD_SIZE;
           }
           past_headers = 1;
       } else if (md_type == MD_TYPE2) {
           n = 0;
           while (n < length - 2) {
               uint16_t tlv_class;
               uint8_t tlv_type, tlv_len, tlv_len_padded;

               tlv_class = GET_BE_U_2(bp);
               bp += 2;
               tlv_type  = GET_U_1(bp);
               bp += 1;
               tlv_len   = GET_U_1(bp) & 0x7f;
               bp += 1;
               tlv_len_padded = roundup2(tlv_len, NSH_HDR_WORD_SIZE);

               ND_PRINT("\n        TLV Class %u, Type %u, Len %u",
                         tlv_class, tlv_type, tlv_len);

               n += 1;

               if (length - 2 < n + tlv_len_padded / NSH_HDR_WORD_SIZE) {
                   ND_PRINT(" (length too big)");
                   goto invalid;
               }

               if (tlv_len) {
                   const char *sep = "0x";
                   u_int vn;

                   ND_PRINT("\n            Value: ");
                   for (vn = 0; vn < tlv_len; vn++) {
                       ND_PRINT("%s%02x", sep, GET_U_1(bp));
                       bp += 1;
                       sep = ":";
                   }
                   /* Cover any TLV padding. */
                   ND_TCHECK_LEN(bp, tlv_len_padded - tlv_len);
                   bp += tlv_len_padded - tlv_len;
                   n += tlv_len_padded / NSH_HDR_WORD_SIZE;
               }
           }
           past_headers = 1;
       }
   }
   if (! past_headers) {
       ND_TCHECK_LEN(bp, (length - 2) * NSH_HDR_WORD_SIZE);
       bp += (length - 2) * NSH_HDR_WORD_SIZE;
   }
   ND_PRINT(ndo->ndo_vflag ? "\n    " : ": ");

   /* print Next Protocol */
   next_len = len - length * NSH_HDR_WORD_SIZE;
   switch (next_protocol) {
   case NP_IPV4:
       ip_print(ndo, bp, next_len);
       break;
   case NP_IPV6:
       ip6_print(ndo, bp, next_len);
       break;
   case NP_ETH:
       ether_print(ndo, bp, next_len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
       break;
   default:
       ND_PRINT("ERROR: unknown-next-protocol");
       return;
   }

   return;

invalid:
   nd_print_invalid(ndo);
}

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