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: RFC 8300 */
  27
  28 #include <config.h>
  29
  30 #include "netdissect-stdinc.h"
  31
  32 #define ND_LONGJMP_FROM_TCHECK
  33 #include "netdissect.h"
  34 #include "extract.h"
  35
  36 static const struct tok nsh_flags [] = {
  37     { 0x2, "O" },
  38     { 0, NULL }
  39 };
  40
  41 /*
  42  *    0                   1                   2                   3
  43  *    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
  44  *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  45  *   |Ver|O|U|    TTL    |   Length  |U|U|U|U|MD Type| Next Protocol |
  46  *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  47  */
  48 #define NSH_BASE_HDR_LEN 4
  49 #define NSH_VER(x)       (((x) & 0xc0000000) >> 30)
  50 #define NSH_FLAGS(x)     (((x) & 0x30000000) >> 28)
  51 #define NSH_TTL(x)       (((x) & 0x0fc00000) >> 22)
  52 #define NSH_LENGTH(x)    (((x) & 0x003f0000) >> 16)
  53 #define NSH_MD_TYPE(x)   (((x) & 0x00000f00) >>  8)
  54 #define NSH_NEXT_PROT(x) (((x) & 0x000000ff) >>  0)
  55
  56 #define NSH_SERVICE_PATH_HDR_LEN 4
  57 #define NSH_HDR_WORD_SIZE 4U
  58
  59 #define MD_RSV   0x00
  60 #define MD_TYPE1 0x01
  61 #define MD_TYPE2 0x02
  62 #define MD_EXP   0x0F
  63 static const struct tok md_str[] = {
  64     { MD_RSV,   "reserved"     },
  65     { MD_TYPE1, "1"            },
  66     { MD_TYPE2, "2"            },
  67     { MD_EXP,   "experimental" },
  68     { 0, NULL }
  69 };
  70
  71 #define NP_IPV4 0x01
  72 #define NP_IPV6 0x02
  73 #define NP_ETH  0x03
  74 #define NP_NSH  0x04
  75 #define NP_MPLS 0x05
  76 #define NP_EXP1 0xFE
  77 #define NP_EXP2 0xFF
  78 static const struct tok np_str[] = {
  79     { NP_IPV4, "IPv4"         },
  80     { NP_IPV6, "IPv6"         },
  81     { NP_ETH,  "Ethernet"     },
  82     { NP_NSH,  "NSH"          },
  83     { NP_MPLS, "MPLS"         },
  84     { NP_EXP1, "Experiment 1" },
  85     { NP_EXP2, "Experiment 2" },
  86     { 0, NULL }
  87 };
  88
  89 void
  90 nsh_print(netdissect_options *ndo, const u_char *bp, u_int len)
  91 {
  92     uint32_t basehdr;
  93     u_int ver, length, md_type;
  94     uint8_t next_protocol;
  95     u_char past_headers = 0;
  96     u_int next_len;
  97
  98     ndo->ndo_protocol = "nsh";
  99     /*
 100      *    0                   1                   2                   3
 101      *    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
 102      *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 103      *   |                Base Header                                    |
 104      *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 105      *   |                Service Path Header                            |
 106      *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 107      *   |                                                               |
 108      *   ~                Context Header(s)                              ~
 109      *   |                                                               |
 110      *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 111      */
 112
 113     /* print Base Header and Service Path Header */
 114     if (len < NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN) {
 115         ND_PRINT(" (packet length %u < %u)",
 116                  len, NSH_BASE_HDR_LEN + NSH_SERVICE_PATH_HDR_LEN);
 117         goto invalid;
 118     }
 119
 120     basehdr = GET_BE_U_4(bp);
 121     bp += 4;
 122     ver = NSH_VER(basehdr);
 123     length = NSH_LENGTH(basehdr);
 124     md_type = NSH_MD_TYPE(basehdr);
 125     next_protocol = NSH_NEXT_PROT(basehdr);
 126
 127     ND_PRINT("NSH, ");
 128     if (ndo->ndo_vflag > 1) {
 129         ND_PRINT("ver %u, ", ver);
 130     }
 131     if (ver != 0)
 132         return;
 133     ND_PRINT("flags [%s], ",
 134              bittok2str_nosep(nsh_flags, "none", NSH_FLAGS(basehdr)));
 135     if (ndo->ndo_vflag > 2) {
 136         ND_PRINT("TTL %u, ", NSH_TTL(basehdr));
 137         ND_PRINT("length %u, ", length);
 138         ND_PRINT("md type %s, ", tok2str(md_str, "unknown (0x%02x)", md_type));
 139     }
 140     if (ndo->ndo_vflag > 1) {
 141         ND_PRINT("next-protocol %s, ",
 142                  tok2str(np_str, "unknown (0x%02x)", next_protocol));
 143     }
 144
 145     /* Make sure we have all the headers */
 146     if (len < length * NSH_HDR_WORD_SIZE) {
 147         ND_PRINT(" (too many headers for packet length %u)", len);
 148         goto invalid;
 149     }
 150
 151     /*
 152      *    0                   1                   2                   3
 153      *    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
 154      *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 155      *   |          Service Path Identifier (SPI)        | Service Index |
 156      *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 157      *
 158      */
 159     ND_PRINT("service-path-id 0x%06x, ", GET_BE_U_3(bp));
 160     bp += 3;
 161     ND_PRINT("service-index 0x%x", GET_U_1(bp));
 162     bp += 1;
 163
 164     /*
 165      * length includes the lengths of the Base and Service Path headers.
 166      * That means it must be at least 2.
 167      */
 168     if (length < 2) {
 169         ND_PRINT(" (less than two headers)");
 170         goto invalid;
 171     }
 172
 173     /*
 174      * Print, or skip, the Context Headers.
 175      * (length - 2) is the length of those headers.
 176      */
 177     if (ndo->ndo_vflag > 2) {
 178         u_int n;
 179
 180         if (md_type == MD_TYPE1) {
 181             if (length != 6) {
 182                 ND_PRINT(" (length for the MD type)");
 183                 goto invalid;
 184             }
 185             for (n = 0; n < length - 2; n++) {
 186                 ND_PRINT("\n        Context[%02u]: 0x%08x", n, GET_BE_U_4(bp));
 187                 bp += NSH_HDR_WORD_SIZE;
 188             }
 189             past_headers = 1;
 190         } else if (md_type == MD_TYPE2) {
 191             n = 0;
 192             while (n < length - 2) {
 193                 uint16_t tlv_class;
 194                 uint8_t tlv_type, tlv_len, tlv_len_padded;
 195
 196                 tlv_class = GET_BE_U_2(bp);
 197                 bp += 2;
 198                 tlv_type  = GET_U_1(bp);
 199                 bp += 1;
 200                 tlv_len   = GET_U_1(bp) & 0x7f;
 201                 bp += 1;
 202                 tlv_len_padded = roundup2(tlv_len, NSH_HDR_WORD_SIZE);
 203
 204                 ND_PRINT("\n        TLV Class %u, Type %u, Len %u",
 205                           tlv_class, tlv_type, tlv_len);
 206
 207                 n += 1;
 208
 209                 if (length - 2 < n + tlv_len_padded / NSH_HDR_WORD_SIZE) {
 210                     ND_PRINT(" (length too big)");
 211                     goto invalid;
 212                 }
 213
 214                 if (tlv_len) {
 215                     const char *sep = "0x";
 216                     u_int vn;
 217
 218                     ND_PRINT("\n            Value: ");
 219                     for (vn = 0; vn < tlv_len; vn++) {
 220                         ND_PRINT("%s%02x", sep, GET_U_1(bp));
 221                         bp += 1;
 222                         sep = ":";
 223                     }
 224                     /* Cover any TLV padding. */
 225                     ND_TCHECK_LEN(bp, tlv_len_padded - tlv_len);
 226                     bp += tlv_len_padded - tlv_len;
 227                     n += tlv_len_padded / NSH_HDR_WORD_SIZE;
 228                 }
 229             }
 230             past_headers = 1;
 231         }
 232     }
 233     if (! past_headers) {
 234         ND_TCHECK_LEN(bp, (length - 2) * NSH_HDR_WORD_SIZE);
 235         bp += (length - 2) * NSH_HDR_WORD_SIZE;
 236     }
 237     ND_PRINT(ndo->ndo_vflag ? "\n    " : ": ");
 238
 239     /* print Next Protocol */
 240     next_len = len - length * NSH_HDR_WORD_SIZE;
 241     switch (next_protocol) {
 242     case NP_IPV4:
 243         ip_print(ndo, bp, next_len);
 244         break;
 245     case NP_IPV6:
 246         ip6_print(ndo, bp, next_len);
 247         break;
 248     case NP_ETH:
 249         ether_print(ndo, bp, next_len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
 250         break;
 251     default:
 252         ND_PRINT("ERROR: unknown-next-protocol");
 253         return;
 254     }
 255
 256     return;
 257
 258 invalid:
 259     nd_print_invalid(ndo);
 260 }
 261