/*
* 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,
[email protected]
*
* Reference documentation:
*
https://web.archive.org/web/20000914194913/http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.pdf
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-cdp.c,v 1.10 2024/09/02 16:15:30 christos Exp $");
#endif
/* \summary: Cisco Discovery Protocol (CDP) printer */
#include <config.h>
#include "netdissect-stdinc.h"
#include <string.h>
#define ND_LONGJMP_FROM_TCHECK
#include "netdissect.h"
#include "addrtoname.h"
#include "extract.h"
#include "nlpid.h"
#define CDP_HEADER_LEN 4
#define CDP_HEADER_VERSION_OFFSET 0
#define CDP_HEADER_TTL_OFFSET 1
#define CDP_HEADER_CHECKSUM_OFFSET 2
#define CDP_TLV_HEADER_LEN 4
#define CDP_TLV_TYPE_OFFSET 0
#define CDP_TLV_LEN_OFFSET 2
static const struct tok cdp_capability_values[] = {
{ 0x01, "Router" },
{ 0x02, "Transparent Bridge" },
{ 0x04, "Source Route Bridge" },
{ 0x08, "L2 Switch" },
{ 0x10, "L3 capable" },
{ 0x20, "IGMP snooping" },
{ 0x40, "L1 capable" },
{ 0, NULL }
};
static void cdp_print_addr(netdissect_options *, const u_char *, u_int);
static void cdp_print_prefixes(netdissect_options *, const u_char *, u_int);
static void
cdp_print_string(netdissect_options *ndo,
const u_char *cp, const u_int len)
{
ND_PRINT("'");
(void)nd_printn(ndo, cp, len, NULL);
ND_PRINT("'");
}
static void
cdp_print_power(netdissect_options *ndo,
const u_char *cp, const u_int len)
{
u_int val = 0;
switch (len) {
case 1:
val = GET_U_1(cp);
break;
case 2:
val = GET_BE_U_2(cp);
break;
case 3:
val = GET_BE_U_3(cp);
break;
}
ND_PRINT("%1.2fW", val / 1000.0);
}
static void
cdp_print_capability(netdissect_options *ndo,
const u_char *cp, const u_int len _U_)
{
uint32_t val = GET_BE_U_4(cp);
ND_PRINT("(0x%08x): %s", val,
bittok2str(cdp_capability_values, "none", val));
}
/* Rework the version string to get a nice indentation. */
static void
cdp_print_version(netdissect_options *ndo,
const u_char *cp, const u_int len)
{
unsigned i;
ND_PRINT("\n\t ");
for (i = 0; i < len; i++) {
u_char c = GET_U_1(cp + i);
if (c == '\n')
ND_PRINT("\n\t ");
else
fn_print_char(ndo, c);
}
}
static void
cdp_print_uint16(netdissect_options *ndo,
const u_char *cp, const u_int len _U_)
{
ND_PRINT("%u", GET_BE_U_2(cp));
}
static void
cdp_print_duplex(netdissect_options *ndo,
const u_char *cp, const u_int len _U_)
{
ND_PRINT("%s", GET_U_1(cp) ? "full": "half");
}
/*
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cata/186/2_12_m/english/release/notes/186rn21m.html
* plus more details from other sources
*
* There are apparently versions of the request with both
* 2 bytes and 3 bytes of value. The 3 bytes of value
* appear to be a 1-byte application type followed by a
* 2-byte VLAN ID; the 2 bytes of value are unknown
* (they're 0x20 0x00 in some captures I've seen; that
* is not a valid VLAN ID, as VLAN IDs are 12 bits).
*
* The replies all appear to be 3 bytes long.
*/
static void
cdp_print_ata186(netdissect_options *ndo,
const u_char *cp, const u_int len)
{
if (len == 2)
ND_PRINT("unknown 0x%04x", GET_BE_U_2(cp));
else
ND_PRINT("app %u, vlan %u", GET_U_1(cp), GET_BE_U_2(cp + 1));
}
static void
cdp_print_mtu(netdissect_options *ndo,
const u_char *cp, const u_int len _U_)
{
ND_PRINT("%u bytes", GET_BE_U_4(cp));
}
static void
cdp_print_uint8x(netdissect_options *ndo,
const u_char *cp, const u_int len _U_)
{
ND_PRINT("0x%02x", GET_U_1(cp));
}
static void
cdp_print_phys_loc(netdissect_options *ndo,
const u_char *cp, const u_int len)
{
ND_PRINT("0x%02x", GET_U_1(cp));
if (len > 1) {
ND_PRINT("/");
(void)nd_printn(ndo, cp + 1, len - 1, NULL);
}
}
struct cdp_tlvinfo {
const char *name;
void (*printer)(netdissect_options *ndo, const u_char *, u_int);
int min_len, max_len;
};
#define T_DEV_ID 0x01
#define T_MAX 0x17
static const struct cdp_tlvinfo cdptlvs[T_MAX + 1] = {
/* 0x00 */
[ T_DEV_ID ] = { "Device-ID", cdp_print_string, -1, -1 },
[ 0x02 ] = { "Address", cdp_print_addr, -1, -1 },
[ 0x03 ] = { "Port-ID", cdp_print_string, -1, -1 },
[ 0x04 ] = { "Capability", cdp_print_capability, 4, 4 },
[ 0x05 ] = { "Version String", cdp_print_version, -1, -1 },
[ 0x06 ] = { "Platform", cdp_print_string, -1, -1 },
[ 0x07 ] = { "Prefixes", cdp_print_prefixes, -1, -1 },
/* not documented */
[ 0x08 ] = { "Protocol-Hello option", NULL, -1, -1 },
/* CDPv2 */
[ 0x09 ] = { "VTP Management Domain", cdp_print_string, -1, -1 },
/* CDPv2 */
[ 0x0a ] = { "Native VLAN ID", cdp_print_uint16, 2, 2 },
/* CDPv2 */
[ 0x0b ] = { "Duplex", cdp_print_duplex, 1, 1 },
/* 0x0c */
/* 0x0d */
/* incomplete doc. */
[ 0x0e ] = { "ATA-186 VoIP VLAN assignment", cdp_print_ata186, 3, 3 },
/* incomplete doc. */
[ 0x0f ] = { "ATA-186 VoIP VLAN request", cdp_print_ata186, 2, 3 },
/* not documented */
[ 0x10 ] = { "power consumption", cdp_print_power, 1, 3 },
/* not documented */
[ 0x11 ] = { "MTU", cdp_print_mtu, 4, 4 },
/* not documented */
[ 0x12 ] = { "AVVID trust bitmap", cdp_print_uint8x, 1, 1 },
/* not documented */
[ 0x13 ] = { "AVVID untrusted ports CoS", cdp_print_uint8x, 1, 1 },
/* not documented */
[ 0x14 ] = { "System Name", cdp_print_string, -1, -1 },
/* not documented */
[ 0x15 ] = { "System Object ID (not decoded)", NULL, -1, -1 },
[ 0x16 ] = { "Management Addresses", cdp_print_addr, 4, -1 },
/* not documented */
[ 0x17 ] = { "Physical Location", cdp_print_phys_loc, 1, -1 },
};
void
cdp_print(netdissect_options *ndo,
const u_char *tptr, u_int length)
{
u_int orig_length = length;
uint16_t checksum;
ndo->ndo_protocol = "cdp";
if (length < CDP_HEADER_LEN) {
ND_PRINT(" (packet length %u < %u)", length, CDP_HEADER_LEN);
goto invalid;
}
ND_PRINT("CDPv%u, ttl: %us",
GET_U_1(tptr + CDP_HEADER_VERSION_OFFSET),
GET_U_1(tptr + CDP_HEADER_TTL_OFFSET));
checksum = GET_BE_U_2(tptr + CDP_HEADER_CHECKSUM_OFFSET);
if (ndo->ndo_vflag)
ND_PRINT(", checksum: 0x%04x (unverified), length %u",
checksum, orig_length);
tptr += CDP_HEADER_LEN;
length -= CDP_HEADER_LEN;
while (length) {
u_int type, len;
const struct cdp_tlvinfo *info;
const char *name;
u_char covered = 0;
if (length < CDP_TLV_HEADER_LEN) {
ND_PRINT(" (remaining packet length %u < %u)",
length, CDP_TLV_HEADER_LEN);
goto invalid;
}
type = GET_BE_U_2(tptr + CDP_TLV_TYPE_OFFSET);
len = GET_BE_U_2(tptr + CDP_TLV_LEN_OFFSET); /* object length includes the 4 bytes header length */
info = type <= T_MAX ? &cdptlvs[type] : NULL;
name = (info && info->name) ? info->name : "unknown field type";
if (len < CDP_TLV_HEADER_LEN) {
if (ndo->ndo_vflag)
ND_PRINT("\n\t%s (0x%02x), TLV length: %u byte%s (too short)",
name, type, len, PLURAL_SUFFIX(len));
else
ND_PRINT(", %s TLV length %u too short",
name, len);
goto invalid;
}
if (len > length) {
ND_PRINT(" (TLV length %u > %u)", len, length);
goto invalid;
}
tptr += CDP_TLV_HEADER_LEN;
length -= CDP_TLV_HEADER_LEN;
len -= CDP_TLV_HEADER_LEN;
/* In non-verbose mode just print Device-ID. */
if (!ndo->ndo_vflag && type == T_DEV_ID)
ND_PRINT(", Device-ID ");
else if (ndo->ndo_vflag)
ND_PRINT("\n\t%s (0x%02x), value length: %u byte%s: ",
name, type, len, PLURAL_SUFFIX(len));
if (info) {
if ((info->min_len > 0 && len < (unsigned)info->min_len) ||
(info->max_len > 0 && len > (unsigned)info->max_len))
ND_PRINT(" (malformed TLV)");
else if (ndo->ndo_vflag || type == T_DEV_ID) {
if (info->printer)
info->printer(ndo, tptr, len);
else
ND_TCHECK_LEN(tptr, len);
/*
* When the type is defined without a printer,
* do not print the hex dump.
*/
covered = 1;
}
}
if (ndo->ndo_vflag && !covered) {
ND_TCHECK_LEN(tptr, len);
print_unknown_data(ndo, tptr, "\n\t ", len);
}
tptr += len;
length -= len;
}
if (ndo->ndo_vflag < 1)
ND_PRINT(", length %u", orig_length);
return;
invalid:
nd_print_invalid(ndo);
ND_TCHECK_LEN(tptr, length);
}
/*
* Protocol type values.
*
* PT_NLPID means that the protocol type field contains an OSI NLPID.
*
* PT_IEEE_802_2 means that the protocol type field contains an IEEE 802.2
* LLC header that specifies that the payload is for that protocol.
*/
#define PT_NLPID 1 /* OSI NLPID */
#define PT_IEEE_802_2 2 /* IEEE 802.2 LLC header */
static void
cdp_print_addr(netdissect_options *ndo,
const u_char * p, u_int l)
{
u_int num;
static const u_char prot_ipv6[] = {
0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00, 0x86, 0xdd
};
if (l < 4) {
ND_PRINT(" (not enough space for num)");
goto invalid;
}
num = GET_BE_U_4(p);
p += 4;
l -= 4;
while (num) {
u_int pt, pl, al;
if (l < 2) {
ND_PRINT(" (not enough space for PT+PL)");
goto invalid;
}
pt = GET_U_1(p); /* type of "protocol" field */
pl = GET_U_1(p + 1); /* length of "protocol" field */
p += 2;
l -= 2;
if (l < pl + 2) {
ND_PRINT(" (not enough space for P+AL)");
goto invalid;
}
/* Skip the protocol for now. */
al = GET_BE_U_2(p + pl); /* address length */
if (pt == PT_NLPID && pl == 1 && GET_U_1(p) == NLPID_IP &&
al == 4) {
/*
* IPv4: protocol type = NLPID, protocol length = 1
* (1-byte NLPID), protocol = 0xcc (NLPID for IPv4),
* address length = 4
*/
p += pl + 2;
l -= pl + 2;
/* p is just beyond al now. */
if (l < al) {
ND_PRINT(" (not enough space for A)");
goto invalid;
}
ND_PRINT("IPv4 (%u) %s", num, GET_IPADDR_STRING(p));
p += al;
l -= al;
} else if (pt == PT_IEEE_802_2 && pl == 8 &&
memcmp(p, prot_ipv6, 8) == 0 && al == 16) {
/*
* IPv6: protocol type = IEEE 802.2 header,
* protocol length = 8 (size of LLC+SNAP header),
* protocol = LLC+SNAP header with the IPv6
* Ethertype, address length = 16
*/
p += pl + 2;
l -= pl + 2;
/* p is just beyond al now. */
if (l < al) {
ND_PRINT(" (not enough space for A)");
goto invalid;
}
ND_PRINT("IPv6 (%u) %s", num, GET_IP6ADDR_STRING(p));
p += al;
l -= al;
} else {
/*
* Generic case: just print raw data
*/
ND_PRINT("pt=0x%02x, pl=%u, pb=", pt, pl);
while (pl != 0) {
ND_PRINT(" %02x", GET_U_1(p));
p++;
l--;
pl--;
}
ND_PRINT(", al=%u, a=", al);
p += 2;
l -= 2;
/* p is just beyond al now. */
if (l < al) {
ND_PRINT(" (not enough space for A)");
goto invalid;
}
while (al != 0) {
ND_PRINT(" %02x", GET_U_1(p));
p++;
l--;
al--;
}
}
num--;
if (num)
ND_PRINT(" ");
}
if (l)
ND_PRINT(" (%u bytes of stray data)", l);
return;
invalid:
ND_TCHECK_LEN(p, l);
}
static void
cdp_print_prefixes(netdissect_options *ndo,
const u_char * p, u_int l)
{
if (l % 5) {
ND_PRINT(" [length %u is not a multiple of 5]", l);
goto invalid;
}
ND_PRINT(" IPv4 Prefixes (%u):", l / 5);
while (l > 0) {
ND_PRINT(" %u.%u.%u.%u/%u",
GET_U_1(p), GET_U_1(p + 1), GET_U_1(p + 2),
GET_U_1(p + 3), GET_U_1(p + 4));
l -= 5;
p += 5;
}
return;
invalid:
ND_TCHECK_LEN(p, l);
}
