packet-cdp.c

   1 /* packet-cdp.c
   2  * Routines for the disassembly of the "Cisco Discovery Protocol"
   3  * (c) Copyright Hannes R. Boehm <hannes@boehm.org>
   4  *
   5  * $Id: packet-cdp.c,v 1.35 2001/01/25 06:14:13 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@zing.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  25  */
  26
  27 #include "config.h"
  28
  29 #ifdef HAVE_SYS_TYPES_H
  30 #include <sys/types.h>
  31 #endif
  32
  33 #include <stdlib.h>
  34 #include <string.h>
  35
  36 #include <glib.h>
  37 #include "packet.h"
  38 #include "strutil.h"
  39 #include "nlpid.h"
  40
  41 /*
  42  * See
  43  *
  44  *      http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm
  45  *
  46  * for some information on CDP.
  47  */
  48
  49 /* Offsets in TLV structure. */
  50 #define TLV_TYPE        0
  51 #define TLV_LENGTH      2
  52
  53 static int proto_cdp = -1;
  54 static int hf_cdp_version = -1;
  55 static int hf_cdp_checksum = -1;
  56 static int hf_cdp_ttl = -1;
  57 static int hf_cdp_tlvtype = -1;
  58 static int hf_cdp_tlvlength = -1;
  59
  60 static gint ett_cdp = -1;
  61 static gint ett_cdp_tlv = -1;
  62 static gint ett_cdp_address = -1;
  63 static gint ett_cdp_capabilities = -1;
  64
  65 static int
  66 dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree);
  67 static void
  68 dissect_capabilities(tvbuff_t *tvb, int offset, int length, proto_tree *tree);
  69 static void
  70 add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
  71   gint len, const gchar *prefix);
  72
  73 #define TYPE_DEVICE_ID          0x0001
  74 #define TYPE_ADDRESS            0x0002
  75 #define TYPE_PORT_ID            0x0003
  76 #define TYPE_CAPABILITIES       0x0004
  77 #define TYPE_IOS_VERSION        0x0005
  78 #define TYPE_PLATFORM           0x0006
  79 #define TYPE_IP_PREFIX          0x0007
  80
  81 #define TYPE_VTP_MGMT_DOMAIN    0x0009 /* Guessed, from tcpdump */
  82 #define TYPE_NATIVE_VLAN        0x000a /* Guessed, from tcpdump */
  83 #define TYPE_DUPLEX             0x000b /* Guessed, from tcpdump */
  84
  85 static const value_string type_vals[] = {
  86         { TYPE_DEVICE_ID,       "Device ID" },
  87         { TYPE_ADDRESS,         "Addresses" },
  88         { TYPE_PORT_ID,         "Port ID" },
  89         { TYPE_CAPABILITIES,    "Capabilities" },
  90         { TYPE_IOS_VERSION,     "Software version" },
  91         { TYPE_PLATFORM,        "Platform" },
  92         { TYPE_IP_PREFIX,       "IP Prefix (used for ODR)" },
  93         { TYPE_VTP_MGMT_DOMAIN, "VTP Management Domain" },
  94         { TYPE_NATIVE_VLAN,     "Native VLAN" },
  95         { TYPE_DUPLEX,          "Duplex" },
  96         { 0,                    NULL },
  97 };
  98
  99 static void
 100 dissect_cdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 101 {
 102     proto_item *ti;
 103     proto_tree *cdp_tree = NULL;
 104     int offset = 0;
 105     guint16 type;
 106     guint16 length;
 107     proto_item *tlvi;
 108     proto_tree *tlv_tree;
 109     int real_length;
 110     guint32 naddresses;
 111     int addr_length;
 112
 113     if (check_col(pinfo->fd, COL_PROTOCOL))
 114         col_set_str(pinfo->fd, COL_PROTOCOL, "CDP");
 115     if (check_col(pinfo->fd, COL_INFO))
 116         col_set_str(pinfo->fd, COL_INFO, "Cisco Discovery Protocol");
 117
 118     if (tree){
 119         ti = proto_tree_add_item(tree, proto_cdp, tvb, offset,
 120                                  tvb_length_remaining(tvb, offset), FALSE);
 121         cdp_tree = proto_item_add_subtree(ti, ett_cdp);
 122
 123         /* CDP header */
 124         proto_tree_add_item(cdp_tree, hf_cdp_version, tvb, offset, 1, FALSE);
 125         offset += 1;
 126         proto_tree_add_uint_format(cdp_tree, hf_cdp_ttl, tvb, offset, 1,
 127                                    tvb_get_guint8(tvb, offset),
 128                                    "TTL: %u seconds",
 129                                    tvb_get_guint8(tvb, offset));
 130         offset += 1;
 131         proto_tree_add_item(cdp_tree, hf_cdp_checksum, tvb, offset, 2, FALSE);
 132         offset += 2;
 133
 134         while (tvb_reported_length_remaining(tvb, offset) != 0) {
 135             type = tvb_get_ntohs(tvb, offset + TLV_TYPE);
 136             length = tvb_get_ntohs(tvb, offset + TLV_LENGTH);
 137
 138             switch (type) {
 139
 140             case TYPE_DEVICE_ID:
 141                 /* Device ID */
 142                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 143                             length, "Device ID: %.*s",
 144                             length - 4,
 145                             tvb_get_ptr(tvb, offset + 4, length - 4));
 146                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 147                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 148                             offset + TLV_TYPE, 2, type);
 149                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 150                             offset + TLV_LENGTH, 2, length);
 151                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 152                             length - 4, "Device ID: %.*s",
 153                             length - 4,
 154                             tvb_get_ptr(tvb, offset + 4, length - 4));
 155                 offset += length;
 156                 break;
 157
 158             case TYPE_ADDRESS:
 159                 /* Addresses */
 160                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 161                             length, "Addresses");
 162                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 163                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 164                             offset + TLV_TYPE, 2, type);
 165                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 166                             offset + TLV_LENGTH, 2, length);
 167                 offset += 4;
 168                 length -= 4;
 169                 naddresses = tvb_get_ntohl(tvb, offset);
 170                 proto_tree_add_text(tlv_tree, tvb, offset, 4,
 171                             "Number of addresses: %u", naddresses);
 172                 offset += 4;
 173                 length -= 4;
 174                 while (naddresses != 0) {
 175                     addr_length = dissect_address_tlv(tvb, offset, length,
 176                                 tlv_tree);
 177                     if (addr_length < 0)
 178                         break;
 179                     offset += addr_length;
 180                     length -= addr_length;
 181
 182                     naddresses--;
 183                 }
 184                 offset += length;
 185                 break;
 186
 187             case TYPE_PORT_ID:
 188                 real_length = length;
 189                 if (tvb_get_guint8(tvb, offset + real_length) != 0x00) {
 190                     /* The length in the TLV doesn't appear to be the
 191                        length of the TLV, as the byte just past it
 192                        isn't the first byte of a 2-byte big-endian
 193                        small integer; make the length of the TLV the length
 194                        in the TLV, plus 4 bytes for the TLV type and length,
 195                        minus 1 because that's what makes one capture work. */
 196                     real_length = length + 3;
 197                 }
 198                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 199                             real_length, "Port ID: %.*s",
 200                             real_length - 4,
 201                             tvb_get_ptr(tvb, offset + 4, real_length - 4));
 202                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 203                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 204                             offset + TLV_TYPE, 2, type);
 205                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 206                             offset + TLV_LENGTH, 2, length);
 207                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 208                             real_length - 4,
 209                             "Sent through Interface: %.*s",
 210                             real_length - 4,
 211                             tvb_get_ptr(tvb, offset + 4, real_length - 4));
 212                 offset += real_length;
 213                 break;
 214
 215             case TYPE_CAPABILITIES:
 216                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 217                             length, "Capabilities");
 218                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 219                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 220                             offset + TLV_TYPE, 2, type);
 221                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 222                             offset + TLV_LENGTH, 2, length);
 223                 offset += 4;
 224                 length -= 4;
 225                 dissect_capabilities(tvb, offset, length, tlv_tree);
 226                 offset += length;
 227                 break;
 228
 229             case TYPE_IOS_VERSION:
 230                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 231                             length, "Software Version");
 232                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 233                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 234                             offset + TLV_TYPE, 2, type);
 235                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 236                             offset + TLV_LENGTH, 2, length);
 237                 add_multi_line_string_to_tree(tlv_tree, tvb, offset + 4,
 238                                 length - 4, "Software Version: ");
 239                 offset += length;
 240                 break;
 241
 242             case TYPE_PLATFORM:
 243                 /* ??? platform */
 244                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 245                             offset, length, "Platform: %.*s",
 246                             length - 4,
 247                             tvb_get_ptr(tvb, offset + 4, length - 4));
 248                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 249                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 250                             offset + TLV_TYPE, 2, type);
 251                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 252                             offset + TLV_LENGTH, 2, length);
 253                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 254                             length - 4, "Platform: %.*s",
 255                             length - 4,
 256                             tvb_get_ptr(tvb, offset + 4, length - 4));
 257                 offset += length;
 258                 break;
 259             case TYPE_IP_PREFIX:
 260                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 261                             length, "IP Prefixes: %d",length/5);
 262
 263                             /* the actual number of prefixes is (length-4)/5
 264                             but if the variable is not a "float" but "integer"
 265                             then length/5=(length-4)/5  :)  */
 266
 267                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 268                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 269                             offset + TLV_TYPE, 2, type);
 270                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 271                             offset + TLV_LENGTH, 2, length);
 272                 offset += 4;
 273                 length -= 4;
 274                 while (length > 0) {
 275                         proto_tree_add_text(tlv_tree, tvb, offset, 5,
 276                                 "IP Prefix = %s/%u",
 277                                 ip_to_str(tvb_get_ptr(tvb, offset, 4)),
 278                                 tvb_get_guint8(tvb,offset+4));
 279                         offset += 5;
 280                         length -= 5;
 281                 }
 282                 break;
 283             case TYPE_VTP_MGMT_DOMAIN:
 284                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 285                             offset, length, "VTP Management Domain: %.*s",
 286                             length - 4,
 287                             tvb_get_ptr(tvb, offset + 4, length - 4));
 288                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 289                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 290                             offset + TLV_TYPE, 2, type);
 291                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 292                             offset + TLV_LENGTH, 2, length);
 293                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 294                             length - 4, "VTP Management Domain: %.*s",
 295                             length - 4,
 296                             tvb_get_ptr(tvb, offset + 4, length - 4));
 297                 offset += length;
 298                 break;
 299             case TYPE_NATIVE_VLAN:
 300                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 301                             offset, length, "Native VLAN: %u",
 302                                            tvb_get_ntohs(tvb, offset + 4));
 303                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 304                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 305                             offset + TLV_TYPE, 2, type);
 306                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 307                             offset + TLV_LENGTH, 2, length);
 308                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 309                             length - 4, "Native VLAN: %u",
 310                                     tvb_get_ntohs(tvb, offset + 4));
 311                 offset += length;
 312                 break;
 313             case TYPE_DUPLEX:
 314                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 315                             offset, length, "Duplex: %s",
 316                                            tvb_get_guint8(tvb, offset + 4) ?
 317                                            "Full" : "Half" );
 318                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 319                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 320                             offset + TLV_TYPE, 2, type);
 321                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 322                             offset + TLV_LENGTH, 2, length);
 323                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 324                             length - 4, "Duplex: %s",
 325                                     tvb_get_guint8(tvb, offset + 4) ?
 326                                     "Full" : "Half" );
 327                 offset += length;
 328                 break;
 329             default:
 330                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 331                             length, "Type: %s, length: %u",
 332                             val_to_str(type, type_vals, "Unknown (0x%04x)"),
 333                             length);
 334                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 335                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 336                             offset + TLV_TYPE, 2, type);
 337                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 338                             offset + TLV_LENGTH, 2, length);
 339                 if (length > 4) {
 340                         proto_tree_add_text(tlv_tree, tvb, offset + 4,
 341                                         length - 4, "Data");
 342                 } else
 343                         return;
 344                 offset += length;
 345             }
 346         }
 347         dissect_data(tvb, offset, pinfo, cdp_tree);
 348     }
 349 }
 350
 351 #define PROTO_TYPE_NLPID        1
 352 #define PROTO_TYPE_IEEE_802_2   2
 353
 354 static const value_string proto_type_vals[] = {
 355         { PROTO_TYPE_NLPID,      "NLPID" },
 356         { PROTO_TYPE_IEEE_802_2, "802.2" },
 357         { 0,                     NULL },
 358 };
 359
 360 static int
 361 dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
 362 {
 363     proto_item *ti;
 364     proto_tree *address_tree;
 365     guint8 protocol_type;
 366     guint8 protocol_length;
 367     int nlpid;
 368     char *protocol_str;
 369     guint16 address_length;
 370     char *address_type_str;
 371     char *address_str;
 372
 373     if (length < 1)
 374         return -1;
 375     ti = proto_tree_add_notext(tree, tvb, offset, length);
 376     address_tree = proto_item_add_subtree(ti, ett_cdp_address);
 377     protocol_type = tvb_get_guint8(tvb, offset);
 378     proto_tree_add_text(address_tree, tvb, offset, 1, "Protocol type: %s",
 379         val_to_str(protocol_type, proto_type_vals, "Unknown (0x%02x)"));
 380     offset += 1;
 381     length -= 1;
 382
 383     if (length < 1) {
 384         proto_item_set_text(ti, "Truncated address");
 385         return -1;
 386     }
 387     protocol_length = tvb_get_guint8(tvb, offset);
 388     proto_tree_add_text(address_tree, tvb, offset, 1, "Protocol length: %u",
 389                         protocol_length);
 390     offset += 1;
 391     length -= 1;
 392
 393     if (length < protocol_length) {
 394         proto_item_set_text(ti, "Truncated address");
 395         if (length != 0) {
 396             proto_tree_add_text(address_tree, tvb, offset, length,
 397               "Protocol: %s (truncated)",
 398               tvb_bytes_to_str(tvb, offset, length));
 399         }
 400         return -1;
 401     }
 402     protocol_str = NULL;
 403     if (protocol_type == PROTO_TYPE_NLPID && protocol_length == 1) {
 404         nlpid = tvb_get_guint8(tvb, offset);
 405         protocol_str = val_to_str(nlpid, nlpid_vals, "Unknown (0x%02x)");
 406     } else
 407         nlpid = -1;
 408     if (protocol_str == NULL)
 409         protocol_str = tvb_bytes_to_str(tvb, offset, protocol_length);
 410     proto_tree_add_text(address_tree, tvb, offset, protocol_length,
 411                         "Protocol: %s", protocol_str);
 412     offset += protocol_length;
 413     length -= protocol_length;
 414
 415     if (length < 2) {
 416         proto_item_set_text(ti, "Truncated address");
 417         return -1;
 418     }
 419     address_length = tvb_get_ntohs(tvb, offset);
 420     proto_tree_add_text(address_tree, tvb, offset, 2, "Address length: %u",
 421                         address_length);
 422     offset += 2;
 423     length -= 2;
 424
 425     if (length < address_length) {
 426         proto_item_set_text(ti, "Truncated address");
 427         if (length != 0) {
 428             proto_tree_add_text(address_tree, tvb, offset, length,
 429               "Address: %s (truncated)",
 430               tvb_bytes_to_str(tvb, offset, length));
 431         }
 432         return -1;
 433     }
 434     /* XXX - the Cisco document seems to be saying that, for 802.2-format
 435        protocol types, 0xAAAA03 0x000000 0x0800 is IPv6, but 0x0800 is
 436        the Ethernet protocol type for IPv4. */
 437     length = 2 + protocol_length + 2 + address_length;
 438     address_type_str = NULL;
 439     address_str = NULL;
 440     if (protocol_type == PROTO_TYPE_NLPID && protocol_length == 1) {
 441         switch (nlpid) {
 442
 443         /* XXX - dissect NLPID_ISO8473_CLNP as OSI CLNP address? */
 444
 445         case NLPID_IP:
 446             if (address_length == 4) {
 447                 /* The address is an IP address. */
 448                 address_type_str = "IP address";
 449                 address_str = ip_to_str(tvb_get_ptr(tvb, offset, 4));
 450             }
 451             break;
 452         }
 453     }
 454     if (address_type_str == NULL)
 455         address_type_str = "Address";
 456     if (address_str == NULL) {
 457         address_str = tvb_bytes_to_str(tvb, offset, address_length);
 458     }
 459     proto_item_set_text(ti, "%s: %s", address_type_str, address_str);
 460     proto_tree_add_text(address_tree, tvb, offset, address_length, "%s: %s",
 461       address_type_str, address_str);
 462     return 2 + protocol_length + 2 + address_length;
 463 }
 464
 465 static void
 466 dissect_capabilities(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
 467 {
 468     proto_item *ti;
 469     proto_tree *capabilities_tree;
 470     guint32 capabilities;
 471
 472     if (length < 4)
 473         return;
 474     capabilities = tvb_get_ntohl(tvb, offset);
 475     ti = proto_tree_add_text(tree, tvb, offset, length, "Capabilities: 0x%08x",
 476         capabilities);
 477     capabilities_tree = proto_item_add_subtree(ti, ett_cdp_capabilities);
 478     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 479         decode_boolean_bitfield(capabilities, 0x01, 4*8,
 480             "Performs level 3 routing",
 481             "Doesn't perform level 3 routing"));
 482     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 483         decode_boolean_bitfield(capabilities, 0x02, 4*8,
 484             "Performs level 2 transparent bridging",
 485             "Doesn't perform level 2 transparent bridging"));
 486     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 487         decode_boolean_bitfield(capabilities, 0x04, 4*8,
 488             "Performs level 2 source-route bridging",
 489             "Doesn't perform level 2 source-route bridging"));
 490     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 491         decode_boolean_bitfield(capabilities, 0x08, 4*8,
 492             "Performs level 2 switching",
 493             "Doesn't perform level 2 switching"));
 494     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 495         decode_boolean_bitfield(capabilities, 0x10, 4*8,
 496             "Sends and receives packets for network-layer protocols",
 497             "Doesn't send or receive packets for network-layer protocols"));
 498     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 499         decode_boolean_bitfield(capabilities, 0x20, 4*8,
 500             "Doesn't forward IGMP Report packets on nonrouter ports",
 501             "Forwards IGMP Report packets on nonrouter ports"));
 502     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 503         decode_boolean_bitfield(capabilities, 0x40, 4*8,
 504             "Provides level 1 functionality",
 505             "Doesn't provide level 1 functionality"));
 506 }
 507
 508 static void
 509 add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
 510   gint len, const gchar *prefix)
 511 {
 512     int prefix_len;
 513     int i;
 514     char blanks[64+1];
 515     gint next;
 516     int line_len;
 517     int data_len;
 518
 519     prefix_len = strlen(prefix);
 520     if (prefix_len > 64)
 521         prefix_len = 64;
 522     for (i = 0; i < prefix_len; i++)
 523         blanks[i] = ' ';
 524     blanks[i] = '\0';
 525     while (len > 0) {
 526         line_len = tvb_find_line_end(tvb, start, len, &next);
 527         data_len = next - start;
 528         proto_tree_add_text(tree, tvb, start, data_len, "%s%.*s", prefix,
 529            line_len, tvb_get_ptr(tvb, start, line_len));
 530         start += data_len;
 531         len -= data_len;
 532         prefix = blanks;
 533     }
 534 }
 535
 536 void
 537 proto_register_cdp(void)
 538 {
 539     static hf_register_info hf[] = {
 540         { &hf_cdp_version,
 541         { "Version",            "cdp.version",  FT_UINT8, BASE_DEC, NULL, 0x0,
 542           "" }},
 543
 544         { &hf_cdp_ttl,
 545         { "TTL",                "cdp.ttl", FT_UINT16, BASE_DEC, NULL, 0x0,
 546           "" }},
 547
 548         { &hf_cdp_checksum,
 549         { "Checksum",           "cdp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
 550           "" }},
 551
 552         { &hf_cdp_tlvtype,
 553         { "Type",               "cdp.tlv.type", FT_UINT16, BASE_HEX, VALS(type_vals), 0x0,
 554           "" }},
 555
 556         { &hf_cdp_tlvlength,
 557         { "Length",             "cdp.tlv.len", FT_UINT16, BASE_DEC, NULL, 0x0,
 558           "" }},
 559     };
 560     static gint *ett[] = {
 561         &ett_cdp,
 562         &ett_cdp_tlv,
 563         &ett_cdp_address,
 564         &ett_cdp_capabilities,
 565     };
 566
 567     proto_cdp = proto_register_protocol("Cisco Discovery Protocol",
 568                                         "CDP", "cdp");
 569     proto_register_field_array(proto_cdp, hf, array_length(hf));
 570     proto_register_subtree_array(ett, array_length(ett));
 571 }
 572
 573 void
 574 proto_reg_handoff_cdp(void)
 575 {
 576     dissector_add("llc.cisco_pid", 0x2000, dissect_cdp, proto_cdp);
 577     dissector_add("fr.cisco", 0x2000, dissect_cdp, proto_cdp);
 578 }