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 char tstr[] = " [|NSH]";
  38 static const struct tok nsh_flags [] = {
  39     { 0x20, "O" },
  40     { 0x10, "C" },
  41     { 0, NULL }
  42 };
  43
  44 #define NSH_BASE_HDR_LEN 4
  45 #define NSH_SERVICE_PATH_HDR_LEN 4
  46 #define NSH_HDR_WORD_SIZE 4U
  47
  48 void
  49 nsh_print(netdissect_options *ndo, const u_char *bp, u_int len)
  50 {
  51     u_int n, vn;
  52     uint8_t ver;
  53     uint8_t flags;
  54     u_int length;
  55     uint8_t md_type;
  56     uint8_t next_protocol;
  57     uint32_t service_path_id;
  58     uint8_t service_index;
  59     uint32_t ctx;
  60     uint16_t tlv_class;
  61     uint8_t tlv_type;
  62     uint8_t tlv_len;
  63     u_int next_len;
  64
  65     ndo->ndo_protocol = "nsh";
  66     /* print Base Header and Service Path Header */
  67     if (len < NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN)
  68         goto trunc;
  69
  70     ND_TCHECK_LEN(bp, NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN);
  71
  72     ver = (uint8_t)(EXTRACT_U_1(bp) >> 6);
  73     flags = EXTRACT_U_1(bp);
  74     bp += 1;
  75     length = EXTRACT_U_1(bp);
  76     bp += 1;
  77     md_type = EXTRACT_U_1(bp);
  78     bp += 1;
  79     next_protocol = EXTRACT_U_1(bp);
  80     bp += 1;
  81     service_path_id = EXTRACT_BE_U_3(bp);
  82     bp += 3;
  83     service_index = EXTRACT_U_1(bp);
  84     bp += 1;
  85
  86     ND_PRINT("NSH, ");
  87     if (ndo->ndo_vflag > 1) {
  88         ND_PRINT("ver %u, ", ver);
  89     }
  90     ND_PRINT("flags [%s], ", bittok2str_nosep(nsh_flags, "none", flags));
  91     if (ndo->ndo_vflag > 2) {
  92         ND_PRINT("length %u, ", length);
  93         ND_PRINT("md type 0x%x, ", md_type);
  94     }
  95     if (ndo->ndo_vflag > 1) {
  96         ND_PRINT("next-protocol 0x%x, ", next_protocol);
  97     }
  98     ND_PRINT("service-path-id 0x%06x, ", service_path_id);
  99     ND_PRINT("service-index 0x%x", service_index);
 100
 101     /* Make sure we have all the headers */
 102     if (len < length * NSH_HDR_WORD_SIZE)
 103         goto trunc;
 104
 105     ND_TCHECK_LEN(bp, length * NSH_HDR_WORD_SIZE);
 106
 107     /*
 108      * length includes the lengths of the Base and Service Path headers.
 109      * That means it must be at least 2.
 110      */
 111     if (length < 2)
 112         goto trunc;
 113
 114     /*
 115      * Print, or skip, the Context Headers.
 116      * (length - 2) is the length of those headers.
 117      */
 118     if (ndo->ndo_vflag > 2) {
 119         if (md_type == 0x01) {
 120             for (n = 0; n < length - 2; n++) {
 121                 ctx = EXTRACT_BE_U_4(bp);
 122                 bp += NSH_HDR_WORD_SIZE;
 123                 ND_PRINT("\n        Context[%02u]: 0x%08x", n, ctx);
 124             }
 125         }
 126         else if (md_type == 0x02) {
 127             n = 0;
 128             while (n < length - 2) {
 129                 tlv_class = EXTRACT_BE_U_2(bp);
 130                 bp += 2;
 131                 tlv_type  = EXTRACT_U_1(bp);
 132                 bp += 1;
 133                 tlv_len   = EXTRACT_U_1(bp);
 134                 bp += 1;
 135
 136                 ND_PRINT("\n        TLV Class %u, Type %u, Len %u",
 137                           tlv_class, tlv_type, tlv_len);
 138
 139                 n += 1;
 140
 141                 if (length - 2 < n + tlv_len) {
 142                     ND_PRINT(" ERROR: invalid-tlv-length");
 143                     return;
 144                 }
 145
 146                 for (vn = 0; vn < tlv_len; vn++) {
 147                     ctx = EXTRACT_BE_U_4(bp);
 148                     bp += NSH_HDR_WORD_SIZE;
 149                     ND_PRINT("\n            Value[%02u]: 0x%08x", vn, ctx);
 150                 }
 151                 n += tlv_len;
 152             }
 153         }
 154         else {
 155             ND_PRINT("ERROR: unknown-next-protocol");
 156             return;
 157         }
 158     }
 159     else {
 160         bp += (length - 2) * NSH_HDR_WORD_SIZE;
 161     }
 162     ND_PRINT(ndo->ndo_vflag ? "\n    " : ": ");
 163
 164     /* print Next Protocol */
 165     next_len = len - length * NSH_HDR_WORD_SIZE;
 166     switch (next_protocol) {
 167     case 0x1:
 168         ip_print(ndo, bp, next_len);
 169         break;
 170     case 0x2:
 171         ip6_print(ndo, bp, next_len);
 172         break;
 173     case 0x3:
 174         ether_print(ndo, bp, next_len, ndo->ndo_snapend - bp, NULL, NULL);
 175         break;
 176     default:
 177         ND_PRINT("ERROR: unknown-next-protocol");
 178         return;
 179     }
 180
 181     return;
 182
 183 trunc:
 184     ND_PRINT("%s", tstr);
 185 }
 186