epan/dissectors/packet-mdshdr.c

   1 /* packet-mdshdr.c
   2  * Routines for dissection of Cisco MDS Switch Internal Header
   3  * Copyright 2001, Dinesh G Dutt <ddutt@andiamo.com>
   4  *
   5  * $Id$
   6  *
   7  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; either version 2
  14  * of the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  24  */
  25
  26 #include "config.h"
  27
  28 #include <glib.h>
  29
  30 #include <epan/packet.h>
  31 #include <etypes.h>
  32 #include <epan/prefs.h>
  33
  34 #define MDSHDR_VERSION_OFFSET             0
  35
  36 /* Mdshdr Control bits */
  37 #define MDSHDR_CTL_IDXDIRECT              1
  38 #define MDSHDR_CTL_IGNACLO                2
  39 #define MDSHDR_CTL_DRP                    4
  40
  41 /* OFFSETS OF FIELDS */
  42 #define MDSHDR_VER_OFFSET                 0
  43 #define MDSHDR_SOF_OFFSET                 1
  44 #define MDSHDR_PKTLEN_OFFSET              2
  45 #define MDSHDR_DIDX_OFFSET                5
  46 #define MDSHDR_SIDX_OFFSET                6
  47 #define MDSHDR_VSAN_OFFSET               13
  48
  49 /* Two size definitions are sufficient */
  50 #define MDSHDR_SIZE_BYTE                 sizeof(gchar)
  51 #define MDSHDR_SIZE_INT16                sizeof(guint16)
  52 #define MDSHDR_SIZE_INT32                sizeof(guint32)
  53
  54 /* Other miscellaneous defines; can't rely on sizeof structs */
  55 #define MDSHDR_MAX_VERSION                0
  56 #define MDSHDR_HEADER_SIZE               16
  57 #define MDSHDR_TRAILER_SIZE               6
  58
  59 /* SOF Encodings */
  60 #define MDSHDR_SOFc1                     0x1
  61 #define MDSHDR_SOFi1                     0x2
  62 #define MDSHDR_SOFn1                     0x3
  63 #define MDSHDR_SOFi2                     0x4
  64 #define MDSHDR_SOFn2                     0x5
  65 #define MDSHDR_SOFi3                     0x6
  66 #define MDSHDR_SOFn3                     0x7
  67 #define MDSHDR_SOFf                      0x8
  68 #define MDSHDR_SOFc4                     0x9
  69 #define MDSHDR_SOFi4                     0xa
  70 #define MDSHDR_SOFn4                     0xb
  71
  72 /* EOF Encodings */
  73 #define MDSHDR_EOFt                      0x1
  74 #define MDSHDR_EOFdt                     0x2
  75 #define MDSHDR_EOFa                      0x4
  76 #define MDSHDR_EOFn                      0x3
  77 #define MDSHDR_EOFdti                    0x6
  78 #define MDSHDR_EOFni                     0x7
  79 #define MDSHDR_EOFrt                     0xa
  80 #define MDSHDR_EOFrti                    0xe
  81 #define MDSHDR_EOF_UNKNOWN               0xb
  82
  83 /* Initialize the protocol and registered fields */
  84 static int proto_mdshdr = -1;
  85 static int hf_mdshdr_sof = -1;
  86 static int hf_mdshdr_pkt_len = -1;
  87 static int hf_mdshdr_dstidx = -1;
  88 static int hf_mdshdr_srcidx = -1;
  89 static int hf_mdshdr_vsan = -1;
  90 static int hf_mdshdr_eof = -1;
  91 static int hf_mdshdr_span = -1;
  92 static int hf_mdshdr_fccrc = -1;
  93
  94 /* Initialize the subtree pointers */
  95 static gint ett_mdshdr = -1;
  96 static gint ett_mdshdr_hdr = -1;
  97 static gint ett_mdshdr_trlr = -1;
  98
  99 static dissector_handle_t data_handle, fc_dissector_handle;
 100
 101 static gboolean decode_if_zero_etype = TRUE;
 102
 103 static const value_string sof_vals[] = {
 104     {MDSHDR_SOFc1,               "SOFc1"},
 105     {MDSHDR_SOFi1,               "SOFi1"},
 106     {MDSHDR_SOFn1,               "SOFn1"},
 107     {MDSHDR_SOFi2,               "SOFi2"},
 108     {MDSHDR_SOFn2,               "SOFn2"},
 109     {MDSHDR_SOFi3,               "SOFi3"},
 110     {MDSHDR_SOFn3,               "SOFn3"},
 111     {MDSHDR_SOFc4,               "SOFc4"},
 112     {MDSHDR_SOFi4,               "SOFi4"},
 113     {MDSHDR_SOFn4,               "SOFn4"},
 114     {MDSHDR_SOFf,                "SOFf"},
 115     {0,                         NULL},
 116 };
 117
 118 static const value_string eof_vals[] = {
 119     {MDSHDR_EOFt,                "EOFt"},
 120     {MDSHDR_EOFdt,               "EOFdt"},
 121     {MDSHDR_EOFa,                "EOFa"},
 122     {MDSHDR_EOFn,                "EOFn"},
 123     {MDSHDR_EOFdti,              "EOFdti"},
 124     {MDSHDR_EOFni,               "EOFni"},
 125     {MDSHDR_EOFrt,               "EOFrt"},
 126     {MDSHDR_EOFrti,              "EOFrti"},
 127     /*{MDSHDR_EOF_UNKNOWN,         ""}, intentionally removed*/
 128     {0,                          NULL},
 129 };
 130
 131 void proto_reg_handoff_mdshdr(void);
 132
 133 static void
 134 dissect_mdshdr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 135 {
 136
 137 /* Set up structures needed to add the protocol subtree and manage it */
 138     proto_item *ti_main, *ti_hdr, *ti_trlr;
 139     proto_item *hidden_item;
 140     proto_tree *mdshdr_tree_main, *mdshdr_tree_hdr, *mdshdr_tree_trlr;
 141     int         offset        = 0;
 142     guint       pktlen;
 143     tvbuff_t   *next_tvb;
 144     guint8      sof, eof;
 145     int         trailer_start = 0; /*0 means "no trailer found"*/
 146
 147     col_set_str(pinfo->cinfo, COL_PROTOCOL, "MDS Header");
 148
 149     col_clear(pinfo->cinfo, COL_INFO);
 150
 151     sof     = tvb_get_guint8(tvb, offset+MDSHDR_SOF_OFFSET) & 0x0F;
 152     pktlen  = tvb_get_ntohs(tvb, offset+MDSHDR_PKTLEN_OFFSET) & 0x1FFF;
 153
 154     /* The Mdshdr trailer is at the end of the frame */
 155     if ((tvb_length(tvb) >= (MDSHDR_HEADER_SIZE + pktlen))
 156         /* Avoid header/trailer overlap if something wrong */
 157         && (pktlen >= MDSHDR_TRAILER_SIZE))  {
 158         trailer_start = MDSHDR_HEADER_SIZE + pktlen - MDSHDR_TRAILER_SIZE;
 159
 160         eof = tvb_get_guint8(tvb, trailer_start);
 161         tvb_set_reported_length(tvb, MDSHDR_HEADER_SIZE+pktlen);
 162     }
 163     else {
 164         eof = MDSHDR_EOF_UNKNOWN;
 165     }
 166
 167     pinfo->sof_eof = 0;
 168
 169     if ((sof == MDSHDR_SOFi3) || (sof == MDSHDR_SOFi2) || (sof == MDSHDR_SOFi1)
 170         || (sof == MDSHDR_SOFi4)) {
 171         pinfo->sof_eof = PINFO_SOF_FIRST_FRAME;
 172     }
 173     else if (sof == MDSHDR_SOFf) {
 174         pinfo->sof_eof = PINFO_SOF_SOFF;
 175     }
 176
 177     if (eof != MDSHDR_EOFn) {
 178         pinfo->sof_eof |= PINFO_EOF_LAST_FRAME;
 179     }
 180     else if (eof != MDSHDR_EOFt) {
 181         pinfo->sof_eof |= PINFO_EOF_INVALID;
 182     }
 183
 184     if (tree) {
 185         ti_main = proto_tree_add_protocol_format(tree, proto_mdshdr, tvb, 0,
 186                                                  MDSHDR_HEADER_SIZE+pktlen,
 187                                                  "MDS Header(%s/%s)",
 188                                                  val_to_str(sof, sof_vals, "Unknown(%u)"),
 189                                                  val_to_str(eof, eof_vals, "Unknown(%u)"));
 190
 191         mdshdr_tree_main = proto_item_add_subtree(ti_main, ett_mdshdr);
 192
 193         /* Add Header part as subtree first */
 194         ti_hdr = proto_tree_add_text(mdshdr_tree_main, tvb, MDSHDR_VER_OFFSET,
 195                                      MDSHDR_HEADER_SIZE, "MDS Header");
 196
 197         mdshdr_tree_hdr = proto_item_add_subtree(ti_hdr, ett_mdshdr_hdr);
 198         hidden_item = proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_sof, tvb, MDSHDR_SOF_OFFSET,
 199                                           MDSHDR_SIZE_BYTE, ENC_BIG_ENDIAN);
 200         PROTO_ITEM_SET_HIDDEN(hidden_item);
 201         proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_pkt_len, tvb, MDSHDR_PKTLEN_OFFSET,
 202                             MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
 203         proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_dstidx, tvb, MDSHDR_DIDX_OFFSET,
 204                             MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
 205         proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_srcidx, tvb, MDSHDR_SIDX_OFFSET,
 206                             MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
 207         proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_vsan, tvb, MDSHDR_VSAN_OFFSET,
 208                             MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
 209         hidden_item = proto_tree_add_item(mdshdr_tree_hdr, hf_mdshdr_span,
 210                                           tvb, MDSHDR_VSAN_OFFSET,
 211                                           MDSHDR_SIZE_INT16, ENC_BIG_ENDIAN);
 212         PROTO_ITEM_SET_HIDDEN(hidden_item);
 213
 214         /* Add Mdshdr Trailer part */
 215         if (tvb_length(tvb) >= MDSHDR_HEADER_SIZE + pktlen
 216             && 0 != trailer_start) {
 217             ti_trlr = proto_tree_add_text(mdshdr_tree_main, tvb, trailer_start,
 218                                           MDSHDR_TRAILER_SIZE,
 219                                           "MDS Trailer");
 220             mdshdr_tree_trlr = proto_item_add_subtree(ti_trlr, ett_mdshdr_trlr);
 221
 222             proto_tree_add_item(mdshdr_tree_trlr, hf_mdshdr_eof, tvb,
 223                                 trailer_start, MDSHDR_SIZE_BYTE, ENC_BIG_ENDIAN);
 224             proto_tree_add_item(mdshdr_tree_trlr, hf_mdshdr_fccrc, tvb,
 225                                 trailer_start+2, MDSHDR_SIZE_INT32, ENC_BIG_ENDIAN);
 226         }
 227         else {
 228             proto_tree_add_text(mdshdr_tree_main, tvb, 0, 0, "MDS Trailer: Not Found");
 229         }
 230     }
 231
 232     if (tvb_length(tvb) >= MDSHDR_HEADER_SIZE + pktlen
 233         && 0 != pktlen /*if something wrong*/) {
 234         next_tvb = tvb_new_subset(tvb, MDSHDR_HEADER_SIZE, pktlen, pktlen);
 235         /* XXX what to do with the rest of this frame? --ArtemTamazov */
 236     }
 237     else {
 238         next_tvb = tvb_new_subset_remaining(tvb, MDSHDR_HEADER_SIZE);
 239     }
 240
 241     /* Call the Fibre Channel dissector */
 242     if (fc_dissector_handle) {
 243         call_dissector(fc_dissector_handle, next_tvb, pinfo, tree);
 244     }
 245     else {
 246         call_dissector(data_handle, next_tvb, pinfo, tree);
 247     }
 248 }
 249
 250
 251 void
 252 proto_register_mdshdr(void)
 253 {
 254
 255     static hf_register_info hf[] = {
 256         { &hf_mdshdr_sof,
 257           {"SOF", "mdshdr.sof", FT_UINT8, BASE_DEC, VALS(sof_vals), 0x0, NULL, HFILL}},
 258
 259         { &hf_mdshdr_pkt_len,
 260           {"Packet Len", "mdshdr.plen", FT_UINT16, BASE_DEC, NULL, 0x1FFF, NULL, HFILL}},
 261
 262         { &hf_mdshdr_dstidx,
 263           {"Dst Index", "mdshdr.dstidx", FT_UINT16, BASE_HEX, NULL, 0xFFC, NULL, HFILL}},
 264
 265         { &hf_mdshdr_srcidx,
 266           {"Src Index", "mdshdr.srcidx", FT_UINT16, BASE_HEX, NULL, 0x3FF, NULL, HFILL}},
 267
 268         { &hf_mdshdr_vsan,
 269           {"VSAN", "mdshdr.vsan", FT_UINT16, BASE_DEC, NULL, 0x0FFF, NULL, HFILL}},
 270
 271         { &hf_mdshdr_eof,
 272           {"EOF", "mdshdr.eof", FT_UINT8, BASE_DEC, VALS(eof_vals), 0x0, NULL, HFILL}},
 273
 274         { &hf_mdshdr_span,
 275           {"SPAN Frame", "mdshdr.span", FT_UINT16, BASE_DEC, NULL, 0xF000, NULL, HFILL}},
 276
 277         { &hf_mdshdr_fccrc,
 278           {"CRC", "mdshdr.crc", FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL}},
 279     };
 280
 281 /* Setup protocol subtree array */
 282     static gint *ett[] = {
 283         &ett_mdshdr,
 284         &ett_mdshdr_hdr,
 285         &ett_mdshdr_trlr
 286     };
 287     module_t *mdshdr_module;
 288
 289 /* Register the protocol name and description */
 290     proto_mdshdr = proto_register_protocol("MDS Header", "MDS Header", "mdshdr");
 291
 292     proto_register_field_array(proto_mdshdr, hf, array_length(hf));
 293     proto_register_subtree_array(ett, array_length(ett));
 294
 295     mdshdr_module = prefs_register_protocol(proto_mdshdr, proto_reg_handoff_mdshdr);
 296     prefs_register_bool_preference(mdshdr_module, "decode_if_etype_zero",
 297                                    "Decode as MDS Header if Ethertype == 0",
 298                                    "A frame is considered for decoding as MDSHDR if either "
 299                                    "ethertype is 0xFCFC or zero. Turn this flag off if you "
 300                                    "don't want ethertype zero to be decoded as MDSHDR. "
 301                                    "This might be useful to avoid problems with test frames.",
 302                                    &decode_if_zero_etype);
 303 }
 304
 305 void
 306 proto_reg_handoff_mdshdr(void)
 307 {
 308     static dissector_handle_t mdshdr_handle;
 309     static gboolean           registered_for_zero_etype = FALSE;
 310     static gboolean           mdshdr_prefs_initialized  = FALSE;
 311
 312     if (!mdshdr_prefs_initialized) {
 313         /*
 314          * This is the first time this has been called (i.e.,
 315          * Wireshark/TShark is starting up), so create a handle for
 316          * the MDS Header dissector, register the dissector for
 317          * ethertype ETHERTYPE_FCFT, and fetch the data and Fibre
 318          * Channel handles.
 319          */
 320         mdshdr_handle = create_dissector_handle(dissect_mdshdr, proto_mdshdr);
 321         dissector_add_uint("ethertype", ETHERTYPE_FCFT, mdshdr_handle);
 322         data_handle   = find_dissector("data");
 323         fc_dissector_handle = find_dissector("fc");
 324         mdshdr_prefs_initialized = TRUE;
 325     }
 326
 327     /*
 328      * Only register the dissector for ethertype 0 if the preference
 329      * is set to do so.
 330      */
 331     if (decode_if_zero_etype) {
 332         /*
 333          * The preference to register for ethertype ETHERTYPE_UNK (0)
 334          * is set; if we're not registered for ethertype ETHERTYPE_UNK,
 335          * do so.
 336          */
 337         if (!registered_for_zero_etype) {
 338             dissector_add_uint("ethertype", ETHERTYPE_UNK, mdshdr_handle);
 339             registered_for_zero_etype = TRUE;
 340         }
 341     } else {
 342         /*
 343          * The preference to register for ethertype ETHERTYPE_UNK (0)
 344          * is not set; if we're registered for ethertype ETHERTYPE_UNK,
 345          * undo that registration.
 346          */
 347         if (registered_for_zero_etype) {
 348             dissector_delete_uint("ethertype", ETHERTYPE_UNK, mdshdr_handle);
 349             registered_for_zero_etype = FALSE;
 350         }
 351     }
 352 }