_cdp.c

This directory contains source code for tcpdump, a tool for network monitoring and data acquisition

/*
 * Copyright (c) 1992, 1993, 1994, 1995, 1996, 1997
 * The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Code by Gert Doering, SpaceNet GmbH, [e-mail]
 *
 * Reference documentation:
 *    http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm
 */

#include <ctype.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>

#include "interfac.h"
#include "a2name.h"
#include "extract.h"            /* must come after interface.h */

static void cdp_print_addr (const u_char * p, int l);
static void cdp_print_prefixes (const u_char * p, int l);

/*
 * Returns non-zero IFF it succeeds in printing the header
 */
void cdp_print (const u_char *p, u_int length, u_int caplen,
                const u_char *esrc, const u_char *edst)
{
  int i, type, len;

  /* Cisco Discovery Protocol
   */
  if (caplen < 12)
  {
    PUTS ("[|cdp]");
    return;
  }

  i = 8;                        /* CDP data starts at offset 8 */
  PRINTF ("CDP v%d, ttl=%ds", p[i], p[i + 1]);
  i += 4;                       /* skip version, TTL and chksum */

  while (i < length)
  {
    if (i + 4 > caplen)
    {
      PUTS ("[!cdp]");
      return;
    }
    type = (p[i] << 8) + p[i+1];
    len = (p[i + 2] << 8) + p[i+3];

    if (vflag)
         PRINTF ("\n\t%02x/%02x", type, len);
    else PRINTF ("\n\t");

    if (i + len > caplen)
    {
      PUTS ("[!cdp]");
      return;
    }

    switch (type)
    {
      case 0x01:
           PRINTF (" DevID '%.*s'", len-4, p+i+4);
           break;
      case 0x02:
           PUTS (" Addr");
           cdp_print_addr (p+i+4, len-4);
           break;
      case 0x03:
           PRINTF (" PortID '%.*s'", len-4, p+i+4);
           break;
      case 0x04:
           PRINTF (" CAP 0x%02x", p[i+7]);
           break;
      case 0x05:
           if (vflag)
                PRINTF (" Version:\n%.*s", len-4, p+i+4);
           else PUTS (" Version: (suppressed)");
           break;
      case 0x06:
           PRINTF (" Platform: '%.*s'", len-4, p+i+4);
           break;
      case 0x07:
           cdp_print_prefixes (p+i+4, len-4);
           break;
      case 0x09:            /* guess - not documented */
           PRINTF (" VTP Management Domain: '%.*s'", len-4, p+i+4);
           break;
      case 0x0a:            /* guess - not documented */
           PRINTF (" Native VLAN ID: %d", (p[i+4] << 8) + p[i+4+1]-1);
           break;
      case 0x0b:            /* guess - not documented */
           PRINTF (" Duplex: %s", p[i+4] ? "full" : "half");
           break;
      default:
           PRINTF (" unknown field type %02x, len %d", type, len);
    }

    /* avoid infinite loop */
    if (len == 0)
       break;
    i += len;
  }
}

static void cdp_print_addr (const u_char *p, int l)
{
  const u_char *endp = p + l;
  int   pl, al, num;

  num = (p[0] << 24) + (p[1] << 16) + (p[2] << 8) + p[3];
  p  += 4;

  PRINTF (" (%d): ", num);

  while (p < endp && num >= 0)
  {
    pl = *(p + 1);
    p += 2;

    /* special case: IPv4, protocol type=0xcc, addr. length=4 */
    if (pl == 1 && *p == 0xcc && p[1] == 0 && p[2] == 4)
    {
      p += 3;
      PRINTF ("IPv4 %d.%d.%d.%d ", p[0], p[1], p[2], p[3]);
      p += 4;
    }
    else
    {                           /* generic case: just print raw data */
      PRINTF ("pt=0x%02x, pl=%d, pb=", *(p - 2), pl);
      while (pl-- > 0)
        PRINTF (" %02x", *p++);
      al = (*p << 8) + *(p + 1);
      PRINTF (", al=%d, a=", al);
      p += 2;
      while (al-- > 0)
        PRINTF (" %02x", *p++);
    }
    PUTS ("  ");
    num--;
  }
}


static void cdp_print_prefixes (const u_char * p, int l)
{
  PRINTF (" IPv4 Prefixes (%d):", l / 5);

  while (l > 0)
  {
    PRINTF (" %d.%d.%d.%d/%d", p[0], p[1], p[2], p[3], p[4]);
    l -= 5;
    p += 5;
  }
}