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 1.7 2001-06-15 07:58:28 itojun 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         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 0x01:
  88                         printf(" DevID '%.*s'", len - 4, p + i + 4);
  89                         break;
  90                 case 0x02:
  91                         printf(" Addr");
  92                         if (cdp_print_addr(p + i + 4, len - 4) < 0)
  93                                 goto trunc;
  94                         break;
  95                 case 0x03:
  96                         printf(" PortID '%.*s'", len - 4, p + i + 4);
  97                         break;
  98                 case 0x04:
  99                         printf(" CAP 0x%02x", (unsigned) p[i + 7]);
 100                         break;
 101                 case 0x05:
 102                         if (vflag > 1)
 103                                 printf(" Version:\n%.*s", len - 4, p + i + 4);
 104                         else
 105                                 printf(" Version: (suppressed)");
 106                         break;
 107                 case 0x06:
 108                         printf(" Platform: '%.*s'", len - 4, p + i + 4);
 109                         break;
 110                 case 0x07:
 111                         if (cdp_print_prefixes(p + i + 4, len - 4) < 0)
 112                                 goto trunc;
 113                         break;
 114                 case 0x09:              /* guess - not documented */
 115                         printf(" VTP Management Domain: '%.*s'", len - 4,
 116                             p + i + 4);
 117                         break;
 118                 case 0x0a:              /* guess - not documented */
 119                         printf(" Native VLAN ID: %d",
 120                             (p[i + 4] << 8) + p[i + 4 + 1] - 1);
 121                         break;
 122                 case 0x0b:              /* guess - not documented */
 123                         printf(" Duplex: %s", p[i + 4] ? "full": "half");
 124                         break;
 125                 default:
 126                         printf(" unknown field type %02x, len %d", type, len);
 127                         break;
 128                 }
 129
 130                 /* avoid infinite loop */
 131                 if (len == 0)
 132                         break;
 133                 i += len;
 134         }
 135
 136         return;
 137
 138 trunc:
 139         printf("[|cdp]");
 140 }
 141
 142 static int
 143 cdp_print_addr(const u_char * p, int l)
 144 {
 145         int pl, al, num;
 146         const u_char *endp = p + l;
 147
 148         num = (p[0] << 24) + (p[1] << 16) + (p[2] << 8) + p[3];
 149         p += 4;
 150
 151         printf(" (%d): ", num);
 152
 153         while (p < endp && num >= 0) {
 154                 if (p + 2 >= endp)
 155                         goto trunc;
 156                 pl = p[1];
 157                 p += 2;
 158
 159                 /* special case: IPv4, protocol type=0xcc, addr. length=4 */
 160                 if (p + 3 >= endp)
 161                         goto trunc;
 162                 if (pl == 1 && *p == 0xcc && p[1] == 0 && p[2] == 4) {
 163                         if (p + 7 >= endp)
 164                                 goto trunc;
 165                         p += 3;
 166
 167                         printf("IPv4 %u.%u.%u.%u ", p[0], p[1], p[2], p[3]);
 168                         p += 4;
 169                 } else {        /* generic case: just print raw data */
 170                         if (p + pl >= endp)
 171                                 goto trunc;
 172                         printf("pt=0x%02x, pl=%d, pb=", *(p - 2), pl);
 173                         while (pl-- > 0)
 174                                 printf(" %02x", *p++);
 175                         al = (*p << 8) + *(p + 1);
 176                         if (p + 2 + al >= endp)
 177                                 goto trunc;
 178                         printf(", al=%d, a=", al);
 179                         p += 2;
 180                         while (al-- > 0)
 181                                 printf(" %02x", *p++);
 182                 }
 183                 printf("  ");
 184                 num--;
 185         }
 186
 187         return 0;
 188
 189 trunc:
 190         return -1;
 191 }
 192
 193
 194 static int
 195 cdp_print_prefixes(const u_char * p, int l)
 196 {
 197         if (l % 5)
 198                 goto trunc;
 199
 200         printf(" IPv4 Prefixes (%d):", l / 5);
 201
 202         while (l > 0) {
 203                 printf(" %u.%u.%u.%u/%u", p[0], p[1], p[2], p[3], p[4]);
 204                 l -= 5;
 205                 p += 5;
 206         }
 207
 208         return 0;
 209
 210 trunc:
 211         return -1;
 212 }