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 1.48 2002/08/18 15:30:38 gerald 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 #include <stdlib.h>
  29 #include <string.h>
  30
  31 #include <glib.h>
  32 #include <epan/packet.h>
  33 #include <epan/strutil.h>
  34 #include "nlpid.h"
  35
  36 /*
  37  * See
  38  *
  39  *      http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm
  40  *
  41  * for some information on CDP.
  42  */
  43
  44 /* Offsets in TLV structure. */
  45 #define TLV_TYPE        0
  46 #define TLV_LENGTH      2
  47
  48 static int proto_cdp = -1;
  49 static int hf_cdp_version = -1;
  50 static int hf_cdp_checksum = -1;
  51 static int hf_cdp_ttl = -1;
  52 static int hf_cdp_tlvtype = -1;
  53 static int hf_cdp_tlvlength = -1;
  54
  55 static gint ett_cdp = -1;
  56 static gint ett_cdp_tlv = -1;
  57 static gint ett_cdp_address = -1;
  58 static gint ett_cdp_capabilities = -1;
  59
  60 static dissector_handle_t data_handle;
  61
  62 static int
  63 dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree);
  64 static void
  65 dissect_capabilities(tvbuff_t *tvb, int offset, int length, proto_tree *tree);
  66 static void
  67 add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
  68   gint len, const gchar *prefix);
  69
  70 #define TYPE_DEVICE_ID          0x0001
  71 #define TYPE_ADDRESS            0x0002
  72 #define TYPE_PORT_ID            0x0003
  73 #define TYPE_CAPABILITIES       0x0004
  74 #define TYPE_IOS_VERSION        0x0005
  75 #define TYPE_PLATFORM           0x0006
  76 #define TYPE_IP_PREFIX          0x0007
  77
  78 #define TYPE_VTP_MGMT_DOMAIN    0x0009 /* Guessed, from tcpdump */
  79 #define TYPE_NATIVE_VLAN        0x000a /* Guessed, from tcpdump */
  80 #define TYPE_DUPLEX             0x000b /* Guessed, from tcpdump */
  81
  82 static const value_string type_vals[] = {
  83         { TYPE_DEVICE_ID,       "Device ID" },
  84         { TYPE_ADDRESS,         "Addresses" },
  85         { TYPE_PORT_ID,         "Port ID" },
  86         { TYPE_CAPABILITIES,    "Capabilities" },
  87         { TYPE_IOS_VERSION,     "Software version" },
  88         { TYPE_PLATFORM,        "Platform" },
  89         { TYPE_IP_PREFIX,       "IP Prefix (used for ODR)" },
  90         { TYPE_VTP_MGMT_DOMAIN, "VTP Management Domain" },
  91         { TYPE_NATIVE_VLAN,     "Native VLAN" },
  92         { TYPE_DUPLEX,          "Duplex" },
  93         { 0,                    NULL },
  94 };
  95
  96 static void
  97 dissect_cdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  98 {
  99     proto_item *ti;
 100     proto_tree *cdp_tree = NULL;
 101     int offset = 0;
 102     guint16 type;
 103     guint16 length;
 104     proto_item *tlvi;
 105     proto_tree *tlv_tree;
 106     int real_length;
 107     guint32 naddresses;
 108     int addr_length;
 109
 110     if (check_col(pinfo->cinfo, COL_PROTOCOL))
 111         col_set_str(pinfo->cinfo, COL_PROTOCOL, "CDP");
 112     if (check_col(pinfo->cinfo, COL_INFO))
 113         col_set_str(pinfo->cinfo, COL_INFO, "Cisco Discovery Protocol");
 114
 115     if (tree){
 116         ti = proto_tree_add_item(tree, proto_cdp, tvb, offset, -1, FALSE);
 117         cdp_tree = proto_item_add_subtree(ti, ett_cdp);
 118
 119         /* CDP header */
 120         proto_tree_add_item(cdp_tree, hf_cdp_version, tvb, offset, 1, FALSE);
 121         offset += 1;
 122         proto_tree_add_uint_format(cdp_tree, hf_cdp_ttl, tvb, offset, 1,
 123                                    tvb_get_guint8(tvb, offset),
 124                                    "TTL: %u seconds",
 125                                    tvb_get_guint8(tvb, offset));
 126         offset += 1;
 127         proto_tree_add_item(cdp_tree, hf_cdp_checksum, tvb, offset, 2, FALSE);
 128         offset += 2;
 129
 130         while (tvb_reported_length_remaining(tvb, offset) != 0) {
 131             type = tvb_get_ntohs(tvb, offset + TLV_TYPE);
 132             length = tvb_get_ntohs(tvb, offset + TLV_LENGTH);
 133             if (length < 4) {
 134                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset, 4,
 135                     "TLV with invalid length %u (< 4)",
 136                     length);
 137                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 138                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 139                             offset + TLV_TYPE, 2, type);
 140                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 141                             offset + TLV_LENGTH, 2, length);
 142                 offset += 4;
 143                 break;
 144             }
 145
 146             switch (type) {
 147
 148             case TYPE_DEVICE_ID:
 149                 /* Device ID */
 150                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 151                             length, "Device ID: %.*s",
 152                             length - 4,
 153                             tvb_get_ptr(tvb, offset + 4, length - 4));
 154                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 155                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 156                             offset + TLV_TYPE, 2, type);
 157                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 158                             offset + TLV_LENGTH, 2, length);
 159                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 160                             length - 4, "Device ID: %.*s",
 161                             length - 4,
 162                             tvb_get_ptr(tvb, offset + 4, length - 4));
 163                 offset += length;
 164                 break;
 165
 166             case TYPE_ADDRESS:
 167                 /* Addresses */
 168                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 169                             length, "Addresses");
 170                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 171                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 172                             offset + TLV_TYPE, 2, type);
 173                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 174                             offset + TLV_LENGTH, 2, length);
 175                 offset += 4;
 176                 length -= 4;
 177                 naddresses = tvb_get_ntohl(tvb, offset);
 178                 proto_tree_add_text(tlv_tree, tvb, offset, 4,
 179                             "Number of addresses: %u", naddresses);
 180                 offset += 4;
 181                 length -= 4;
 182                 while (naddresses != 0) {
 183                     addr_length = dissect_address_tlv(tvb, offset, length,
 184                                 tlv_tree);
 185                     if (addr_length < 0)
 186                         break;
 187                     offset += addr_length;
 188                     length -= addr_length;
 189
 190                     naddresses--;
 191                 }
 192                 offset += length;
 193                 break;
 194
 195             case TYPE_PORT_ID:
 196                 real_length = length;
 197                 if (tvb_get_guint8(tvb, offset + real_length) != 0x00) {
 198                     /* The length in the TLV doesn't appear to be the
 199                        length of the TLV, as the byte just past it
 200                        isn't the first byte of a 2-byte big-endian
 201                        small integer; make the length of the TLV the length
 202                        in the TLV, plus 4 bytes for the TLV type and length,
 203                        minus 1 because that's what makes one capture work. */
 204                     real_length = length + 3;
 205                 }
 206                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 207                             real_length, "Port ID: %.*s",
 208                             real_length - 4,
 209                             tvb_get_ptr(tvb, offset + 4, real_length - 4));
 210                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 211                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 212                             offset + TLV_TYPE, 2, type);
 213                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 214                             offset + TLV_LENGTH, 2, length);
 215                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 216                             real_length - 4,
 217                             "Sent through Interface: %.*s",
 218                             real_length - 4,
 219                             tvb_get_ptr(tvb, offset + 4, real_length - 4));
 220                 offset += real_length;
 221                 break;
 222
 223             case TYPE_CAPABILITIES:
 224                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 225                             length, "Capabilities");
 226                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 227                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 228                             offset + TLV_TYPE, 2, type);
 229                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 230                             offset + TLV_LENGTH, 2, length);
 231                 offset += 4;
 232                 length -= 4;
 233                 dissect_capabilities(tvb, offset, length, tlv_tree);
 234                 offset += length;
 235                 break;
 236
 237             case TYPE_IOS_VERSION:
 238                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 239                             length, "Software Version");
 240                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 241                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 242                             offset + TLV_TYPE, 2, type);
 243                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 244                             offset + TLV_LENGTH, 2, length);
 245                 add_multi_line_string_to_tree(tlv_tree, tvb, offset + 4,
 246                                 length - 4, "Software Version: ");
 247                 offset += length;
 248                 break;
 249
 250             case TYPE_PLATFORM:
 251                 /* ??? platform */
 252                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 253                             offset, length, "Platform: %.*s",
 254                             length - 4,
 255                             tvb_get_ptr(tvb, offset + 4, length - 4));
 256                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 257                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 258                             offset + TLV_TYPE, 2, type);
 259                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 260                             offset + TLV_LENGTH, 2, length);
 261                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 262                             length - 4, "Platform: %.*s",
 263                             length - 4,
 264                             tvb_get_ptr(tvb, offset + 4, length - 4));
 265                 offset += length;
 266                 break;
 267             case TYPE_IP_PREFIX:
 268                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 269                             length, "IP Prefixes: %d",length/5);
 270
 271                             /* the actual number of prefixes is (length-4)/5
 272                             but if the variable is not a "float" but "integer"
 273                             then length/5=(length-4)/5  :)  */
 274
 275                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 276                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 277                             offset + TLV_TYPE, 2, type);
 278                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 279                             offset + TLV_LENGTH, 2, length);
 280                 offset += 4;
 281                 length -= 4;
 282                 while (length > 0) {
 283                         proto_tree_add_text(tlv_tree, tvb, offset, 5,
 284                                 "IP Prefix = %s/%u",
 285                                 ip_to_str(tvb_get_ptr(tvb, offset, 4)),
 286                                 tvb_get_guint8(tvb,offset+4));
 287                         offset += 5;
 288                         length -= 5;
 289                 }
 290                 break;
 291             case TYPE_VTP_MGMT_DOMAIN:
 292                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 293                             offset, length, "VTP Management Domain: %.*s",
 294                             length - 4,
 295                             tvb_get_ptr(tvb, offset + 4, length - 4));
 296                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 297                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 298                             offset + TLV_TYPE, 2, type);
 299                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 300                             offset + TLV_LENGTH, 2, length);
 301                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 302                             length - 4, "VTP Management Domain: %.*s",
 303                             length - 4,
 304                             tvb_get_ptr(tvb, offset + 4, length - 4));
 305                 offset += length;
 306                 break;
 307             case TYPE_NATIVE_VLAN:
 308                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 309                             offset, length, "Native VLAN: %u",
 310                                            tvb_get_ntohs(tvb, offset + 4));
 311                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 312                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 313                             offset + TLV_TYPE, 2, type);
 314                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 315                             offset + TLV_LENGTH, 2, length);
 316                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 317                             length - 4, "Native VLAN: %u",
 318                                     tvb_get_ntohs(tvb, offset + 4));
 319                 offset += length;
 320                 break;
 321             case TYPE_DUPLEX:
 322                 tlvi = proto_tree_add_text(cdp_tree, tvb,
 323                             offset, length, "Duplex: %s",
 324                                            tvb_get_guint8(tvb, offset + 4) ?
 325                                            "Full" : "Half" );
 326                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 327                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 328                             offset + TLV_TYPE, 2, type);
 329                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 330                             offset + TLV_LENGTH, 2, length);
 331                 proto_tree_add_text(tlv_tree, tvb, offset + 4,
 332                             length - 4, "Duplex: %s",
 333                                     tvb_get_guint8(tvb, offset + 4) ?
 334                                     "Full" : "Half" );
 335                 offset += length;
 336                 break;
 337             default:
 338                 tlvi = proto_tree_add_text(cdp_tree, tvb, offset,
 339                             length, "Type: %s, length: %u",
 340                             val_to_str(type, type_vals, "Unknown (0x%04x)"),
 341                             length);
 342                 tlv_tree = proto_item_add_subtree(tlvi, ett_cdp_tlv);
 343                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvtype, tvb,
 344                             offset + TLV_TYPE, 2, type);
 345                 proto_tree_add_uint(tlv_tree, hf_cdp_tlvlength, tvb,
 346                             offset + TLV_LENGTH, 2, length);
 347                 if (length > 4) {
 348                         proto_tree_add_text(tlv_tree, tvb, offset + 4,
 349                                         length - 4, "Data");
 350                 } else
 351                         return;
 352                 offset += length;
 353             }
 354         }
 355         call_dissector(data_handle, tvb_new_subset(tvb, offset, -1, -1), pinfo,
 356                         cdp_tree);
 357     }
 358 }
 359
 360 #define PROTO_TYPE_NLPID        1
 361 #define PROTO_TYPE_IEEE_802_2   2
 362
 363 static const value_string proto_type_vals[] = {
 364         { PROTO_TYPE_NLPID,      "NLPID" },
 365         { PROTO_TYPE_IEEE_802_2, "802.2" },
 366         { 0,                     NULL },
 367 };
 368
 369 static int
 370 dissect_address_tlv(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
 371 {
 372     proto_item *ti;
 373     proto_tree *address_tree;
 374     guint8 protocol_type;
 375     guint8 protocol_length;
 376     int nlpid;
 377     char *protocol_str;
 378     guint16 address_length;
 379     char *address_type_str;
 380     char *address_str;
 381
 382     if (length < 1)
 383         return -1;
 384     ti = proto_tree_add_text(tree, tvb, offset, length, "Truncated address");
 385     address_tree = proto_item_add_subtree(ti, ett_cdp_address);
 386     protocol_type = tvb_get_guint8(tvb, offset);
 387     proto_tree_add_text(address_tree, tvb, offset, 1, "Protocol type: %s",
 388         val_to_str(protocol_type, proto_type_vals, "Unknown (0x%02x)"));
 389     offset += 1;
 390     length -= 1;
 391
 392     if (length < 1)
 393         return -1;
 394     protocol_length = tvb_get_guint8(tvb, offset);
 395     proto_tree_add_text(address_tree, tvb, offset, 1, "Protocol length: %u",
 396                         protocol_length);
 397     offset += 1;
 398     length -= 1;
 399
 400     if (length < protocol_length) {
 401         if (length != 0) {
 402             proto_tree_add_text(address_tree, tvb, offset, length,
 403               "Protocol: %s (truncated)",
 404               tvb_bytes_to_str(tvb, offset, length));
 405         }
 406         return -1;
 407     }
 408     protocol_str = NULL;
 409     if (protocol_type == PROTO_TYPE_NLPID && protocol_length == 1) {
 410         nlpid = tvb_get_guint8(tvb, offset);
 411         protocol_str = val_to_str(nlpid, nlpid_vals, "Unknown (0x%02x)");
 412     } else
 413         nlpid = -1;
 414     if (protocol_str == NULL)
 415         protocol_str = tvb_bytes_to_str(tvb, offset, protocol_length);
 416     proto_tree_add_text(address_tree, tvb, offset, protocol_length,
 417                         "Protocol: %s", protocol_str);
 418     offset += protocol_length;
 419     length -= protocol_length;
 420
 421     if (length < 2)
 422         return -1;
 423     address_length = tvb_get_ntohs(tvb, offset);
 424     proto_tree_add_text(address_tree, tvb, offset, 2, "Address length: %u",
 425                         address_length);
 426     offset += 2;
 427     length -= 2;
 428
 429     if (length < address_length) {
 430         if (length != 0) {
 431             proto_tree_add_text(address_tree, tvb, offset, length,
 432               "Address: %s (truncated)",
 433               tvb_bytes_to_str(tvb, offset, length));
 434         }
 435         return -1;
 436     }
 437     /* XXX - the Cisco document seems to be saying that, for 802.2-format
 438        protocol types, 0xAAAA03 0x000000 0x0800 is IPv6, but 0x0800 is
 439        the Ethernet protocol type for IPv4. */
 440     length = 2 + protocol_length + 2 + address_length;
 441     address_type_str = NULL;
 442     address_str = NULL;
 443     if (protocol_type == PROTO_TYPE_NLPID && protocol_length == 1) {
 444         switch (nlpid) {
 445
 446         /* XXX - dissect NLPID_ISO8473_CLNP as OSI CLNP address? */
 447
 448         case NLPID_IP:
 449             if (address_length == 4) {
 450                 /* The address is an IP address. */
 451                 address_type_str = "IP address";
 452                 address_str = ip_to_str(tvb_get_ptr(tvb, offset, 4));
 453             }
 454             break;
 455         }
 456     }
 457     if (address_type_str == NULL)
 458         address_type_str = "Address";
 459     if (address_str == NULL) {
 460         address_str = tvb_bytes_to_str(tvb, offset, address_length);
 461     }
 462     proto_item_set_text(ti, "%s: %s", address_type_str, address_str);
 463     proto_tree_add_text(address_tree, tvb, offset, address_length, "%s: %s",
 464       address_type_str, address_str);
 465     return 2 + protocol_length + 2 + address_length;
 466 }
 467
 468 static void
 469 dissect_capabilities(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
 470 {
 471     proto_item *ti;
 472     proto_tree *capabilities_tree;
 473     guint32 capabilities;
 474
 475     if (length < 4)
 476         return;
 477     capabilities = tvb_get_ntohl(tvb, offset);
 478     ti = proto_tree_add_text(tree, tvb, offset, length, "Capabilities: 0x%08x",
 479         capabilities);
 480     capabilities_tree = proto_item_add_subtree(ti, ett_cdp_capabilities);
 481     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 482         decode_boolean_bitfield(capabilities, 0x01, 4*8,
 483             "Performs level 3 routing",
 484             "Doesn't perform level 3 routing"));
 485     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 486         decode_boolean_bitfield(capabilities, 0x02, 4*8,
 487             "Performs level 2 transparent bridging",
 488             "Doesn't perform level 2 transparent bridging"));
 489     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 490         decode_boolean_bitfield(capabilities, 0x04, 4*8,
 491             "Performs level 2 source-route bridging",
 492             "Doesn't perform level 2 source-route bridging"));
 493     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 494         decode_boolean_bitfield(capabilities, 0x08, 4*8,
 495             "Performs level 2 switching",
 496             "Doesn't perform level 2 switching"));
 497     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 498         decode_boolean_bitfield(capabilities, 0x10, 4*8,
 499             "Sends and receives packets for network-layer protocols",
 500             "Doesn't send or receive packets for network-layer protocols"));
 501     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 502         decode_boolean_bitfield(capabilities, 0x20, 4*8,
 503             "Doesn't forward IGMP Report packets on nonrouter ports",
 504             "Forwards IGMP Report packets on nonrouter ports"));
 505     proto_tree_add_text(capabilities_tree, tvb, offset, 4,
 506         decode_boolean_bitfield(capabilities, 0x40, 4*8,
 507             "Provides level 1 functionality",
 508             "Doesn't provide level 1 functionality"));
 509 }
 510
 511 static void
 512 add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
 513   gint len, const gchar *prefix)
 514 {
 515     int prefix_len;
 516     int i;
 517     char blanks[64+1];
 518     gint next;
 519     int line_len;
 520     int data_len;
 521
 522     prefix_len = strlen(prefix);
 523     if (prefix_len > 64)
 524         prefix_len = 64;
 525     for (i = 0; i < prefix_len; i++)
 526         blanks[i] = ' ';
 527     blanks[i] = '\0';
 528     while (len > 0) {
 529         line_len = tvb_find_line_end(tvb, start, len, &next, FALSE);
 530         data_len = next - start;
 531         proto_tree_add_text(tree, tvb, start, data_len, "%s%.*s", prefix,
 532            line_len, tvb_get_ptr(tvb, start, line_len));
 533         start += data_len;
 534         len -= data_len;
 535         prefix = blanks;
 536     }
 537 }
 538
 539 void
 540 proto_register_cdp(void)
 541 {
 542     static hf_register_info hf[] = {
 543         { &hf_cdp_version,
 544         { "Version",            "cdp.version",  FT_UINT8, BASE_DEC, NULL, 0x0,
 545           "", HFILL }},
 546
 547         { &hf_cdp_ttl,
 548         { "TTL",                "cdp.ttl", FT_UINT16, BASE_DEC, NULL, 0x0,
 549           "", HFILL }},
 550
 551         { &hf_cdp_checksum,
 552         { "Checksum",           "cdp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
 553           "", HFILL }},
 554
 555         { &hf_cdp_tlvtype,
 556         { "Type",               "cdp.tlv.type", FT_UINT16, BASE_HEX, VALS(type_vals), 0x0,
 557           "", HFILL }},
 558
 559         { &hf_cdp_tlvlength,
 560         { "Length",             "cdp.tlv.len", FT_UINT16, BASE_DEC, NULL, 0x0,
 561           "", HFILL }},
 562     };
 563     static gint *ett[] = {
 564         &ett_cdp,
 565         &ett_cdp_tlv,
 566         &ett_cdp_address,
 567         &ett_cdp_capabilities,
 568     };
 569
 570     proto_cdp = proto_register_protocol("Cisco Discovery Protocol",
 571                                         "CDP", "cdp");
 572     proto_register_field_array(proto_cdp, hf, array_length(hf));
 573     proto_register_subtree_array(ett, array_length(ett));
 574 }
 575
 576 void
 577 proto_reg_handoff_cdp(void)
 578 {
 579     dissector_handle_t cdp_handle;
 580
 581     data_handle = find_dissector("data");
 582     cdp_handle = create_dissector_handle(dissect_cdp, proto_cdp);
 583     dissector_add("llc.cisco_pid", 0x2000, cdp_handle);
 584     dissector_add("chdlctype", 0x2000, cdp_handle);
 585     dissector_add("ppp.protocol", 0x0207, cdp_handle);
 586 }