The Tcpdump Group git mirrors - tcpdump/blob - print-cdp.c

   1 /*
   2  * Copyright (c) 1992, 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  *
  21  * Code by Gert Doering, SpaceNet GmbH, gert@space.net
  22  *
  23  * Reference documentation:
  24  *    http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm
  25  */
  26
  27 #ifndef lint
  28 static const char rcsid[] =
  29     "@(#) $Header: /tcpdump/master/tcpdump/print-cdp.c,v 1.11 2001-09-17 21:57:56 fenner Exp $";
  30 #endif
  31
  32 #ifdef HAVE_CONFIG_H
  33 #include "config.h"
  34 #endif
  35
  36 #include <sys/param.h>
  37 #include <sys/time.h>
  38
  39 #include <netinet/in.h>
  40
  41 #include <ctype.h>
  42 #include <netdb.h>
  43 #include <stdio.h>
  44 #include <string.h>
  45
  46 #include "interface.h"
  47 #include "addrtoname.h"
  48 #include "extract.h"                    /* must come after interface.h */
  49
  50 static int cdp_print_addr(const u_char *, int);
  51 static int cdp_print_prefixes(const u_char *, int);
  52
  53 void
  54 cdp_print(const u_char *p, u_int length, u_int caplen,
  55           const u_char *esrc, const u_char *edst)
  56 {
  57         u_int i;
  58         int type, len;
  59
  60         /* Cisco Discovery Protocol */
  61
  62         if (caplen < 4) {
  63                 (void)printf("[|cdp]");
  64                 return;
  65         }
  66
  67         i = 0;          /* CDP data starts at offset 0 */
  68         printf("CDP v%u, ttl=%us", p[i], p[i + 1]);
  69         i += 4;         /* skip version, TTL and chksum */
  70
  71         while (i < length) {
  72                 if (i + 4 > caplen)
  73                         goto trunc;
  74                 type = (p[i] <<  8) + p[i + 1];
  75                 len  = (p[i + 2] << 8) + p[i + 3];
  76
  77                 if (vflag > 1)
  78                         printf("\n\t");
  79
  80                 if (vflag)
  81                         printf(" %02x/%02x", type, len);
  82
  83                 if (i + len > caplen)
  84                         goto trunc;
  85
  86                 switch (type) {
  87                 case 0x00:
  88                         printf(" Goodbye");
  89                         break;
  90                 case 0x01:
  91                         printf(" DevID '%.*s'", len - 4, p + i + 4);
  92                         break;
  93                 case 0x02:
  94                         printf(" Addr");
  95                         if (cdp_print_addr(p + i + 4, len - 4) < 0)
  96                                 goto trunc;
  97                         break;
  98                 case 0x03:
  99                         printf(" PortID '%.*s'", len - 4, p + i + 4);
 100                         break;
 101                 case 0x04:
 102                         printf(" CAP 0x%02x", (unsigned) p[i + 7]);
 103                         break;
 104                 case 0x05:
 105                         if (vflag > 1)
 106                                 printf(" Version:\n%.*s", len - 4, p + i + 4);
 107                         else
 108                                 printf(" Version: (suppressed)");
 109                         break;
 110                 case 0x06:
 111                         printf(" Platform: '%.*s'", len - 4, p + i + 4);
 112                         break;
 113                 case 0x07:
 114                         if (cdp_print_prefixes(p + i + 4, len - 4) < 0)
 115                                 goto trunc;
 116                         break;
 117                 case 0x09:              /* guess - not documented */
 118                         printf(" VTP Management Domain: '%.*s'", len - 4,
 119                             p + i + 4);
 120                         break;
 121                 case 0x0a:              /* guess - not documented */
 122                         printf(" Native VLAN ID: %d",
 123                             (p[i + 4] << 8) + p[i + 4 + 1] - 1);
 124                         break;
 125                 case 0x0b:              /* guess - not documented */
 126                         printf(" Duplex: %s", p[i + 4] ? "full": "half");
 127                         break;
 128                 default:
 129                         printf(" unknown field type %02x, len %d", type, len);
 130                         break;
 131                 }
 132
 133                 /* avoid infinite loop */
 134                 if (len == 0)
 135                         break;
 136                 i += len;
 137         }
 138
 139         return;
 140
 141 trunc:
 142         printf("[|cdp]");
 143 }
 144
 145 /*
 146  * Protocol type values.
 147  *
 148  * PT_NLPID means that the protocol type field contains an OSI NLPID.
 149  *
 150  * PT_IEEE_802_2 means that the protocol type field contains an IEEE 802.2
 151  * LLC header that specifies that the payload is for that protocol.
 152  */
 153 #define PT_NLPID                1       /* OSI NLPID */
 154 #define PT_IEEE_802_2           2       /* IEEE 802.2 LLC header */
 155
 156 static int
 157 cdp_print_addr(const u_char * p, int l)
 158 {
 159         int pt, pl, al, num;
 160         const u_char *endp = p + l;
 161 #ifdef INET6
 162         static u_char prot_ipv6[] = {
 163                 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00, 0x86, 0xdd
 164         };
 165 #endif
 166
 167         num = EXTRACT_32BITS(p);
 168         p += 4;
 169
 170         printf(" (%d): ", num);
 171
 172         while (p < endp && num >= 0) {
 173                 if (p + 2 > endp)
 174                         goto trunc;
 175                 pt = p[0];              /* type of "protocol" field */
 176                 pl = p[1];              /* length of "protocol" field */
 177                 p += 2;
 178
 179                 if (p + pl + 2 > endp)
 180                         goto trunc;
 181                 al = EXTRACT_16BITS(&p[pl]);    /* address length */
 182
 183                 if (pt == PT_NLPID && pl == 1 && *p == 0xcc && al == 4) {
 184                         /*
 185                          * IPv4: protocol type = NLPID, protocol length = 1
 186                          * (1-byte NLPID), protocol = 0xcc (NLPID for IPv4),
 187                          * address length = 4
 188                          */
 189                         p += 3;
 190
 191                         if (p + 4 > endp)
 192                                 goto trunc;
 193                         printf("IPv4 %u.%u.%u.%u", p[0], p[1], p[2], p[3]);
 194                         p += 4;
 195                 }
 196 #ifdef INET6
 197                 else if (pt == PT_IEEE_802_2 && pl == 8 &&
 198                     memcmp(p, prot_ipv6, 8) == 0 && al == 16) {
 199                         /*
 200                          * IPv6: protocol type = IEEE 802.2 header,
 201                          * protocol length = 8 (size of LLC+SNAP header),
 202                          * protocol = LLC+SNAP header with the IPv6
 203                          * Ethertype, address length = 16
 204                          */
 205                         p += 10;
 206                         if (p + al > endp)
 207                                 goto trunc;
 208
 209                         printf("IPv6 %s", ip6addr_string(p));
 210                         p += al;
 211                 }
 212 #endif
 213                 else {
 214                         /*
 215                          * Generic case: just print raw data
 216                          */
 217                         if (p + pl > endp)
 218                                 goto trunc;
 219                         printf("pt=0x%02x, pl=%d, pb=", *(p - 2), pl);
 220                         while (pl-- > 0)
 221                                 printf(" %02x", *p++);
 222                         if (p + 2 > endp)
 223                                 goto trunc;
 224                         al = (*p << 8) + *(p + 1);
 225                         printf(", al=%d, a=", al);
 226                         p += 2;
 227                         if (p + al > endp)
 228                                 goto trunc;
 229                         while (al-- > 0)
 230                                 printf(" %02x", *p++);
 231                 }
 232                 num--;
 233                 if (num)
 234                         printf(" ");
 235         }
 236
 237         return 0;
 238
 239 trunc:
 240         return -1;
 241 }
 242
 243
 244 static int
 245 cdp_print_prefixes(const u_char * p, int l)
 246 {
 247         if (l % 5)
 248                 goto trunc;
 249
 250         printf(" IPv4 Prefixes (%d):", l / 5);
 251
 252         while (l > 0) {
 253                 printf(" %u.%u.%u.%u/%u", p[0], p[1], p[2], p[3], p[4]);
 254                 l -= 5;
 255                 p += 5;
 256         }
 257
 258         return 0;
 259
 260 trunc:
 261         return -1;
 262 }