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 1.44 2002/01/24 09:20:47 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@ethereal.com>
   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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  24  */
  25
  26 #include "config.h"
  27
  28 #ifdef HAVE_SYS_TYPES_H
  29 #include <sys/types.h>
  30 #endif
  31
  32 #include <stdlib.h>
  33 #include <string.h>
  34
  35 #include <glib.h>
  36 #include <epan/packet.h>
  37 #include <epan/strutil.h>
  38 #include "nlpid.h"
  39
  40 /*
  41  * See
  42  *
  43  *      http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm
  44  *
  45  * for some information on CDP.
  46  */
  47
  48 /* Offsets in TLV structure. */
  49 #define TLV_TYPE        0
  50 #define TLV_LENGTH      2
  51
  52 static int proto_cdp = -1;
  53 static int hf_cdp_version = -1;
  54 static int hf_cdp_checksum = -1;
  55 static int hf_cdp_ttl = -1;
  56 static int hf_cdp_tlvtype = -1;
  57 static int hf_cdp_tlvlength = -1;
  58
  59 static gint ett_cdp = -1;
  60 static gint ett_cdp_tlv = -1;
  61 static gint ett_cdp_address = -1;
  62 static gint ett_cdp_capabilities = -1;
  63
  64 static dissector_handle_t data_handle;
  65
  66 static int
  67 dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree);
  68 static void
  69 dissect_capabilities(tvbuff_t *tvb, int offset, int length, proto_tree *tree);
  70 static void
  71 add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
  72   gint len, const gchar *prefix);
  73
  74 #define TYPE_DEVICE_ID          0x0001
  75 #define TYPE_ADDRESS            0x0002
  76 #define TYPE_PORT_ID            0x0003
  77 #define TYPE_CAPABILITIES       0x0004
  78 #define TYPE_IOS_VERSION        0x0005
  79 #define TYPE_PLATFORM           0x0006
  80 #define TYPE_IP_PREFIX          0x0007
  81
  82 #define TYPE_VTP_MGMT_DOMAIN    0x0009 /* Guessed, from tcpdump */
  83 #define TYPE_NATIVE_VLAN        0x000a /* Guessed, from tcpdump */
  84 #define TYPE_DUPLEX             0x000b /* Guessed, from tcpdump */
  85
  86 static const value_string type_vals[] = {
  87         { TYPE_DEVICE_ID,       "Device ID" },
  88         { TYPE_ADDRESS,         "Addresses" },
  89         { TYPE_PORT_ID,         "Port ID" },
  90         { TYPE_CAPABILITIES,    "Capabilities" },
  91         { TYPE_IOS_VERSION,     "Software version" },
  92         { TYPE_PLATFORM,        "Platform" },
  93         { TYPE_IP_PREFIX,       "IP Prefix (used for ODR)" },
  94         { TYPE_VTP_MGMT_DOMAIN, "VTP Management Domain" },
  95         { TYPE_NATIVE_VLAN,     "Native VLAN" },
  96         { TYPE_DUPLEX,          "Duplex" },
  97         { 0,                    NULL },
  98 };
  99
 100 static void
 101 dissect_cdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 102 {
 103     proto_item *ti;
 104     proto_tree *cdp_tree = NULL;
 105     int offset = 0;
 106     guint16 type;
 107     guint16 length;
 108     proto_item *tlvi;
 109     proto_tree *tlv_tree;
 110     int real_length;
 111     guint32 naddresses;
 112     int addr_length;
 113
 114     if (check_col(pinfo->cinfo, COL_PROTOCOL))
 115         col_set_str(pinfo->cinfo, COL_PROTOCOL, "CDP");
 116     if (check_col(pinfo->cinfo, COL_INFO))
 117         col_set_str(pinfo->cinfo, COL_INFO, "Cisco Discovery Protocol");
 118
 119     if (tree){
 120         ti = proto_tree_add_item(tree, proto_cdp, tvb, offset, -1, 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             if (length < 4) {
 138                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset, 4,
 139                     "TLV with invalid length %u (< 4)",
 140                     length);
 141                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 142                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 143                             offset + TLV_TYPE, 2, type);
 144                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 145                             offset + TLV_LENGTH, 2, length);
 146                 offset += 4;
 147                 break;
 148             }
 149
 150             switch (type) {
 151
 152             case TYPE_DEVICE_ID:
 153                 /* Device ID */
 154                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 155                             length, "Device ID: %.*s",
 156                             length - 4,
 157                             tvb_get_ptr(tvb, offset + 4, length - 4));
 158                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 159                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 160                             offset + TLV_TYPE, 2, type);
 161                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 162                             offset + TLV_LENGTH, 2, length);
 163                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 164                             length - 4, "Device ID: %.*s",
 165                             length - 4,
 166                             tvb_get_ptr(tvb, offset + 4, length - 4));
 167                 offset += length;
 168                 break;
 169
 170             case TYPE_ADDRESS:
 171                 /* Addresses */
 172                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 173                             length, "Addresses");
 174                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 175                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 176                             offset + TLV_TYPE, 2, type);
 177                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 178                             offset + TLV_LENGTH, 2, length);
 179                 offset += 4;
 180                 length -= 4;
 181                 naddresses = tvb_get_ntohl(tvb, offset);
 182                 proto_tree_add_text(tlv_tree, tvb, offset, 4,
 183                             "Number of addresses: %u", naddresses);
 184                 offset += 4;
 185                 length -= 4;
 186                 while (naddresses != 0) {
 187                     addr_length = dissect_address_tlv(tvb, offset, length,
 188                                 tlv_tree);
 189                     if (addr_length < 0)
 190                         break;
 191                     offset += addr_length;
 192                     length -= addr_length;
 193
 194                     naddresses--;
 195                 }
 196                 offset += length;
 197                 break;
 198
 199             case TYPE_PORT_ID:
 200                 real_length = length;
 201                 if (tvb_get_guint8(tvb, offset + real_length) != 0x00) {
 202                     /* The length in the TLV doesn't appear to be the
 203                        length of the TLV, as the byte just past it
 204                        isn't the first byte of a 2-byte big-endian
 205                        small integer; make the length of the TLV the length
 206                        in the TLV, plus 4 bytes for the TLV type and length,
 207                        minus 1 because that's what makes one capture work. */
 208                     real_length = length + 3;
 209                 }
 210                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 211                             real_length, "Port ID: %.*s",
 212                             real_length - 4,
 213                             tvb_get_ptr(tvb, offset + 4, real_length - 4));
 214                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 215                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 216                             offset + TLV_TYPE, 2, type);
 217                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 218                             offset + TLV_LENGTH, 2, length);
 219                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 220                             real_length - 4,
 221                             "Sent through Interface: %.*s",
 222                             real_length - 4,
 223                             tvb_get_ptr(tvb, offset + 4, real_length - 4));
 224                 offset += real_length;
 225                 break;
 226
 227             case TYPE_CAPABILITIES:
 228                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 229                             length, "Capabilities");
 230                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 231                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 232                             offset + TLV_TYPE, 2, type);
 233                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 234                             offset + TLV_LENGTH, 2, length);
 235                 offset += 4;
 236                 length -= 4;
 237                 dissect_capabilities(tvb, offset, length, tlv_tree);
 238                 offset += length;
 239                 break;
 240
 241             case TYPE_IOS_VERSION:
 242                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 243                             length, "Software Version");
 244                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 245                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 246                             offset + TLV_TYPE, 2, type);
 247                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 248                             offset + TLV_LENGTH, 2, length);
 249                 add_multi_line_string_to_tree(tlv_tree, tvb, offset + 4,
 250                                 length - 4, "Software Version: ");
 251                 offset += length;
 252                 break;
 253
 254             case TYPE_PLATFORM:
 255                 /* ??? platform */
 256                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 257                             offset, length, "Platform: %.*s",
 258                             length - 4,
 259                             tvb_get_ptr(tvb, offset + 4, length - 4));
 260                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 261                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 262                             offset + TLV_TYPE, 2, type);
 263                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 264                             offset + TLV_LENGTH, 2, length);
 265                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 266                             length - 4, "Platform: %.*s",
 267                             length - 4,
 268                             tvb_get_ptr(tvb, offset + 4, length - 4));
 269                 offset += length;
 270                 break;
 271             case TYPE_IP_PREFIX:
 272                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 273                             length, "IP Prefixes: %d",length/5);
 274
 275                             /* the actual number of prefixes is (length-4)/5
 276                             but if the variable is not a "float" but "integer"
 277                             then length/5=(length-4)/5  :)  */
 278
 279                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 280                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 281                             offset + TLV_TYPE, 2, type);
 282                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 283                             offset + TLV_LENGTH, 2, length);
 284                 offset += 4;
 285                 length -= 4;
 286                 while (length > 0) {
 287                         proto_tree_add_text(tlv_tree, tvb, offset, 5,
 288                                 "IP Prefix = %s/%u",
 289                                 ip_to_str(tvb_get_ptr(tvb, offset, 4)),
 290                                 tvb_get_guint8(tvb,offset+4));
 291                         offset += 5;
 292                         length -= 5;
 293                 }
 294                 break;
 295             case TYPE_VTP_MGMT_DOMAIN:
 296                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 297                             offset, length, "VTP Management Domain: %.*s",
 298                             length - 4,
 299                             tvb_get_ptr(tvb, offset + 4, length - 4));
 300                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 301                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 302                             offset + TLV_TYPE, 2, type);
 303                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 304                             offset + TLV_LENGTH, 2, length);
 305                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 306                             length - 4, "VTP Management Domain: %.*s",
 307                             length - 4,
 308                             tvb_get_ptr(tvb, offset + 4, length - 4));
 309                 offset += length;
 310                 break;
 311             case TYPE_NATIVE_VLAN:
 312                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 313                             offset, length, "Native VLAN: %u",
 314                                            tvb_get_ntohs(tvb, offset + 4));
 315                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 316                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 317                             offset + TLV_TYPE, 2, type);
 318                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 319                             offset + TLV_LENGTH, 2, length);
 320                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 321                             length - 4, "Native VLAN: %u",
 322                                     tvb_get_ntohs(tvb, offset + 4));
 323                 offset += length;
 324                 break;
 325             case TYPE_DUPLEX:
 326                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 327                             offset, length, "Duplex: %s",
 328                                            tvb_get_guint8(tvb, offset + 4) ?
 329                                            "Full" : "Half" );
 330                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 331                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 332                             offset + TLV_TYPE, 2, type);
 333                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 334                             offset + TLV_LENGTH, 2, length);
 335                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 336                             length - 4, "Duplex: %s",
 337                                     tvb_get_guint8(tvb, offset + 4) ?
 338                                     "Full" : "Half" );
 339                 offset += length;
 340                 break;
 341             default:
 342                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 343                             length, "Type: %s, length: %u",
 344                             val_to_str(type, type_vals, "Unknown (0x%04x)"),
 345                             length);
 346                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 347                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 348                             offset + TLV_TYPE, 2, type);
 349                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 350                             offset + TLV_LENGTH, 2, length);
 351                 if (length > 4) {
 352                         proto_tree_add_text(tlv_tree, tvb, offset + 4,
 353                                         length - 4, "Data");
 354                 } else
 355                         return;
 356                 offset += length;
 357             }
 358         }
 359         call_dissector(data_handle,tvb_new_subset(tvb, offset,-1,tvb_reported_length_remaining(tvb,offset)), pinfo, cdp_tree);
 360     }
 361 }
 362
 363 #define PROTO_TYPE_NLPID        1
 364 #define PROTO_TYPE_IEEE_802_2   2
 365
 366 static const value_string proto_type_vals[] = {
 367         { PROTO_TYPE_NLPID,      "NLPID" },
 368         { PROTO_TYPE_IEEE_802_2, "802.2" },
 369         { 0,                     NULL },
 370 };
 371
 372 static int
 373 dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
 374 {
 375     proto_item *ti;
 376     proto_tree *address_tree;
 377     guint8 protocol_type;
 378     guint8 protocol_length;
 379     int nlpid;
 380     char *protocol_str;
 381     guint16 address_length;
 382     char *address_type_str;
 383     char *address_str;
 384
 385     if (length < 1)
 386         return -1;
 387     ti = proto_tree_add_text(tree, tvb, offset, length, "Truncated address");
 388     address_tree = proto_item_add_subtree(ti, ett_cdp_address);
 389     protocol_type = tvb_get_guint8(tvb, offset);
 390     proto_tree_add_text(address_tree, tvb, offset, 1, "Protocol type: %s",
 391         val_to_str(protocol_type, proto_type_vals, "Unknown (0x%02x)"));
 392     offset += 1;
 393     length -= 1;
 394
 395     if (length < 1)
 396         return -1;
 397     protocol_length = tvb_get_guint8(tvb, offset);
 398     proto_tree_add_text(address_tree, tvb, offset, 1, "Protocol length: %u",
 399                         protocol_length);
 400     offset += 1;
 401     length -= 1;
 402
 403     if (length < protocol_length) {
 404         if (length != 0) {
 405             proto_tree_add_text(address_tree, tvb, offset, length,
 406               "Protocol: %s (truncated)",
 407               tvb_bytes_to_str(tvb, offset, length));
 408         }
 409         return -1;
 410     }
 411     protocol_str = NULL;
 412     if (protocol_type == PROTO_TYPE_NLPID && protocol_length == 1) {
 413         nlpid = tvb_get_guint8(tvb, offset);
 414         protocol_str = val_to_str(nlpid, nlpid_vals, "Unknown (0x%02x)");
 415     } else
 416         nlpid = -1;
 417     if (protocol_str == NULL)
 418         protocol_str = tvb_bytes_to_str(tvb, offset, protocol_length);
 419     proto_tree_add_text(address_tree, tvb, offset, protocol_length,
 420                         "Protocol: %s", protocol_str);
 421     offset += protocol_length;
 422     length -= protocol_length;
 423
 424     if (length < 2)
 425         return -1;
 426     address_length = tvb_get_ntohs(tvb, offset);
 427     proto_tree_add_text(address_tree, tvb, offset, 2, "Address length: %u",
 428                         address_length);
 429     offset += 2;
 430     length -= 2;
 431
 432     if (length < address_length) {
 433         if (length != 0) {
 434             proto_tree_add_text(address_tree, tvb, offset, length,
 435               "Address: %s (truncated)",
 436               tvb_bytes_to_str(tvb, offset, length));
 437         }
 438         return -1;
 439     }
 440     /* XXX - the Cisco document seems to be saying that, for 802.2-format
 441        protocol types, 0xAAAA03 0x000000 0x0800 is IPv6, but 0x0800 is
 442        the Ethernet protocol type for IPv4. */
 443     length = 2 + protocol_length + 2 + address_length;
 444     address_type_str = NULL;
 445     address_str = NULL;
 446     if (protocol_type == PROTO_TYPE_NLPID && protocol_length == 1) {
 447         switch (nlpid) {
 448
 449         /* XXX - dissect NLPID_ISO8473_CLNP as OSI CLNP address? */
 450
 451         case NLPID_IP:
 452             if (address_length == 4) {
 453                 /* The address is an IP address. */
 454                 address_type_str = "IP address";
 455                 address_str = ip_to_str(tvb_get_ptr(tvb, offset, 4));
 456             }
 457             break;
 458         }
 459     }
 460     if (address_type_str == NULL)
 461         address_type_str = "Address";
 462     if (address_str == NULL) {
 463         address_str = tvb_bytes_to_str(tvb, offset, address_length);
 464     }
 465     proto_item_set_text(ti, "%s: %s", address_type_str, address_str);
 466     proto_tree_add_text(address_tree, tvb, offset, address_length, "%s: %s",
 467       address_type_str, address_str);
 468     return 2 + protocol_length + 2 + address_length;
 469 }
 470
 471 static void
 472 dissect_capabilities(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
 473 {
 474     proto_item *ti;
 475     proto_tree *capabilities_tree;
 476     guint32 capabilities;
 477
 478     if (length < 4)
 479         return;
 480     capabilities = tvb_get_ntohl(tvb, offset);
 481     ti = proto_tree_add_text(tree, tvb, offset, length, "Capabilities: 0x%08x",
 482         capabilities);
 483     capabilities_tree = proto_item_add_subtree(ti, ett_cdp_capabilities);
 484     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 485         decode_boolean_bitfield(capabilities, 0x01, 4*8,
 486             "Performs level 3 routing",
 487             "Doesn't perform level 3 routing"));
 488     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 489         decode_boolean_bitfield(capabilities, 0x02, 4*8,
 490             "Performs level 2 transparent bridging",
 491             "Doesn't perform level 2 transparent bridging"));
 492     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 493         decode_boolean_bitfield(capabilities, 0x04, 4*8,
 494             "Performs level 2 source-route bridging",
 495             "Doesn't perform level 2 source-route bridging"));
 496     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 497         decode_boolean_bitfield(capabilities, 0x08, 4*8,
 498             "Performs level 2 switching",
 499             "Doesn't perform level 2 switching"));
 500     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 501         decode_boolean_bitfield(capabilities, 0x10, 4*8,
 502             "Sends and receives packets for network-layer protocols",
 503             "Doesn't send or receive packets for network-layer protocols"));
 504     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 505         decode_boolean_bitfield(capabilities, 0x20, 4*8,
 506             "Doesn't forward IGMP Report packets on nonrouter ports",
 507             "Forwards IGMP Report packets on nonrouter ports"));
 508     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 509         decode_boolean_bitfield(capabilities, 0x40, 4*8,
 510             "Provides level 1 functionality",
 511             "Doesn't provide level 1 functionality"));
 512 }
 513
 514 static void
 515 add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
 516   gint len, const gchar *prefix)
 517 {
 518     int prefix_len;
 519     int i;
 520     char blanks[64+1];
 521     gint next;
 522     int line_len;
 523     int data_len;
 524
 525     prefix_len = strlen(prefix);
 526     if (prefix_len > 64)
 527         prefix_len = 64;
 528     for (i = 0; i < prefix_len; i++)
 529         blanks[i] = ' ';
 530     blanks[i] = '\0';
 531     while (len > 0) {
 532         line_len = tvb_find_line_end(tvb, start, len, &next);
 533         data_len = next - start;
 534         proto_tree_add_text(tree, tvb, start, data_len, "%s%.*s", prefix,
 535            line_len, tvb_get_ptr(tvb, start, line_len));
 536         start += data_len;
 537         len -= data_len;
 538         prefix = blanks;
 539     }
 540 }
 541
 542 void
 543 proto_register_cdp(void)
 544 {
 545     static hf_register_info hf[] = {
 546         { &hf_cdp_version,
 547         { "Version",            "cdp.version",  FT_UINT8, BASE_DEC, NULL, 0x0,
 548           "", HFILL }},
 549
 550         { &hf_cdp_ttl,
 551         { "TTL",                "cdp.ttl", FT_UINT16, BASE_DEC, NULL, 0x0,
 552           "", HFILL }},
 553
 554         { &hf_cdp_checksum,
 555         { "Checksum",           "cdp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
 556           "", HFILL }},
 557
 558         { &hf_cdp_tlvtype,
 559         { "Type",               "cdp.tlv.type", FT_UINT16, BASE_HEX, VALS(type_vals), 0x0,
 560           "", HFILL }},
 561
 562         { &hf_cdp_tlvlength,
 563         { "Length",             "cdp.tlv.len", FT_UINT16, BASE_DEC, NULL, 0x0,
 564           "", HFILL }},
 565     };
 566     static gint *ett[] = {
 567         &ett_cdp,
 568         &ett_cdp_tlv,
 569         &ett_cdp_address,
 570         &ett_cdp_capabilities,
 571     };
 572
 573     proto_cdp = proto_register_protocol("Cisco Discovery Protocol",
 574                                         "CDP", "cdp");
 575     proto_register_field_array(proto_cdp, hf, array_length(hf));
 576     proto_register_subtree_array(ett, array_length(ett));
 577 }
 578
 579 void
 580 proto_reg_handoff_cdp(void)
 581 {
 582     dissector_handle_t cdp_handle;
 583
 584     data_handle = find_dissector("data");
 585     cdp_handle = create_dissector_handle(dissect_cdp, proto_cdp);
 586     dissector_add("llc.cisco_pid", 0x2000, cdp_handle);
 587     dissector_add("chdlctype", 0x2000, cdp_handle);
 588 }