The Tcpdump Group git mirrors - tcpdump/blob - print-nsh.c

   1 /* Copyright (c) 2015, bugyo
   2  * 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 are met:
   6  * 1. Redistributions of source code must retain the above copyright notice,
   7  *    this list of conditions and the following disclaimer.
   8  * 2. Redistributions in binary form must reproduce the above copyright notice,
   9  *    this list of conditions and the following disclaimer in the documentation
  10  *    and/or other materials provided with the distribution.
  11  *
  12  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  13  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  14  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  15  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
  16  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  17  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  18  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  19  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  20  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  21  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  22  */
  23
  24 /* \summary: Network Service Header (NSH) printer */
  25
  26 /* specification: draft-ietf-sfc-nsh-01 */
  27
  28 #ifdef HAVE_CONFIG_H
  29 #include <config.h>
  30 #endif
  31
  32 #include "netdissect-stdinc.h"
  33
  34 #include "netdissect.h"
  35 #include "extract.h"
  36
  37 static const struct tok nsh_flags [] = {
  38     { 0x20, "O" },
  39     { 0x10, "C" },
  40     { 0, NULL }
  41 };
  42
  43 #define NSH_BASE_HDR_LEN 4
  44 #define NSH_SERVICE_PATH_HDR_LEN 4
  45 #define NSH_HDR_WORD_SIZE 4U
  46
  47 void
  48 nsh_print(netdissect_options *ndo, const u_char *bp, u_int len)
  49 {
  50     u_int n, vn;
  51     uint8_t ver;
  52     uint8_t flags;
  53     u_int length;
  54     uint8_t md_type;
  55     uint8_t next_protocol;
  56     uint32_t service_path_id;
  57     uint8_t service_index;
  58     uint32_t ctx;
  59     uint16_t tlv_class;
  60     uint8_t tlv_type;
  61     uint8_t tlv_len;
  62     u_int next_len;
  63
  64     ndo->ndo_protocol = "nsh";
  65     /* print Base Header and Service Path Header */
  66     if (len < NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN)
  67         goto trunc;
  68
  69     ND_TCHECK_LEN(bp, NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN);
  70
  71     ver = (uint8_t)(GET_U_1(bp) >> 6);
  72     flags = GET_U_1(bp);
  73     bp += 1;
  74     length = GET_U_1(bp);
  75     bp += 1;
  76     md_type = GET_U_1(bp);
  77     bp += 1;
  78     next_protocol = GET_U_1(bp);
  79     bp += 1;
  80     service_path_id = GET_BE_U_3(bp);
  81     bp += 3;
  82     service_index = GET_U_1(bp);
  83     bp += 1;
  84
  85     ND_PRINT("NSH, ");
  86     if (ndo->ndo_vflag > 1) {
  87         ND_PRINT("ver %u, ", ver);
  88     }
  89     ND_PRINT("flags [%s], ", bittok2str_nosep(nsh_flags, "none", flags));
  90     if (ndo->ndo_vflag > 2) {
  91         ND_PRINT("length %u, ", length);
  92         ND_PRINT("md type 0x%x, ", md_type);
  93     }
  94     if (ndo->ndo_vflag > 1) {
  95         ND_PRINT("next-protocol 0x%x, ", next_protocol);
  96     }
  97     ND_PRINT("service-path-id 0x%06x, ", service_path_id);
  98     ND_PRINT("service-index 0x%x", service_index);
  99
 100     /* Make sure we have all the headers */
 101     if (len < length * NSH_HDR_WORD_SIZE)
 102         goto trunc;
 103
 104     ND_TCHECK_LEN(bp, length * NSH_HDR_WORD_SIZE);
 105
 106     /*
 107      * length includes the lengths of the Base and Service Path headers.
 108      * That means it must be at least 2.
 109      */
 110     if (length < 2)
 111         goto trunc;
 112
 113     /*
 114      * Print, or skip, the Context Headers.
 115      * (length - 2) is the length of those headers.
 116      */
 117     if (ndo->ndo_vflag > 2) {
 118         if (md_type == 0x01) {
 119             for (n = 0; n < length - 2; n++) {
 120                 ctx = GET_BE_U_4(bp);
 121                 bp += NSH_HDR_WORD_SIZE;
 122                 ND_PRINT("\n        Context[%02u]: 0x%08x", n, ctx);
 123             }
 124         }
 125         else if (md_type == 0x02) {
 126             n = 0;
 127             while (n < length - 2) {
 128                 tlv_class = GET_BE_U_2(bp);
 129                 bp += 2;
 130                 tlv_type  = GET_U_1(bp);
 131                 bp += 1;
 132                 tlv_len   = GET_U_1(bp);
 133                 bp += 1;
 134
 135                 ND_PRINT("\n        TLV Class %u, Type %u, Len %u",
 136                           tlv_class, tlv_type, tlv_len);
 137
 138                 n += 1;
 139
 140                 if (length - 2 < n + tlv_len) {
 141                     ND_PRINT(" ERROR: invalid-tlv-length");
 142                     return;
 143                 }
 144
 145                 for (vn = 0; vn < tlv_len; vn++) {
 146                     ctx = GET_BE_U_4(bp);
 147                     bp += NSH_HDR_WORD_SIZE;
 148                     ND_PRINT("\n            Value[%02u]: 0x%08x", vn, ctx);
 149                 }
 150                 n += tlv_len;
 151             }
 152         }
 153         else {
 154             ND_PRINT("ERROR: unknown-next-protocol");
 155             return;
 156         }
 157     }
 158     else {
 159         bp += (length - 2) * NSH_HDR_WORD_SIZE;
 160     }
 161     ND_PRINT(ndo->ndo_vflag ? "\n    " : ": ");
 162
 163     /* print Next Protocol */
 164     next_len = len - length * NSH_HDR_WORD_SIZE;
 165     switch (next_protocol) {
 166     case 0x1:
 167         ip_print(ndo, bp, next_len);
 168         break;
 169     case 0x2:
 170         ip6_print(ndo, bp, next_len);
 171         break;
 172     case 0x3:
 173         ether_print(ndo, bp, next_len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
 174         break;
 175     default:
 176         ND_PRINT("ERROR: unknown-next-protocol");
 177         return;
 178     }
 179
 180     return;
 181
 182 trunc:
 183     nd_print_trunc(ndo);
 184 }
 185