1/*
2 * Copyright (c) 1998-2007 The TCPDUMP project
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that: (1) source code
6 * distributions retain the above copyright notice and this paragraph
7 * in its entirety, and (2) distributions including binary code include
8 * the above copyright notice and this paragraph in its entirety in
9 * the documentation or other materials provided with the distribution.
10 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
11 * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
12 * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
13 * FOR A PARTICULAR PURPOSE.
14 *
15 * Original code by Carles Kishimoto <carles.kishimoto@gmail.com>
16 */
17
18/* \summary: Cisco UniDirectional Link Detection (UDLD) protocol printer */
19
20/* specification: RFC 5171 */
21
22#ifdef HAVE_CONFIG_H
23#include "config.h"
24#endif
25
26#include <netdissect-stdinc.h>
27
28#include "netdissect.h"
29#include "extract.h"
30
31static const char tstr[] = " [|udld]";
32
33#define UDLD_HEADER_LEN			4
34#define UDLD_DEVICE_ID_TLV		0x0001
35#define UDLD_PORT_ID_TLV		0x0002
36#define UDLD_ECHO_TLV			0x0003
37#define UDLD_MESSAGE_INTERVAL_TLV	0x0004
38#define UDLD_TIMEOUT_INTERVAL_TLV	0x0005
39#define UDLD_DEVICE_NAME_TLV		0x0006
40#define UDLD_SEQ_NUMBER_TLV		0x0007
41
42static const struct tok udld_tlv_values[] = {
43    { UDLD_DEVICE_ID_TLV, "Device-ID TLV"},
44    { UDLD_PORT_ID_TLV, "Port-ID TLV"},
45    { UDLD_ECHO_TLV, "Echo TLV"},
46    { UDLD_MESSAGE_INTERVAL_TLV, "Message Interval TLV"},
47    { UDLD_TIMEOUT_INTERVAL_TLV, "Timeout Interval TLV"},
48    { UDLD_DEVICE_NAME_TLV, "Device Name TLV"},
49    { UDLD_SEQ_NUMBER_TLV,"Sequence Number TLV"},
50    { 0, NULL}
51};
52
53static const struct tok udld_code_values[] = {
54    { 0x00, "Reserved"},
55    { 0x01, "Probe message"},
56    { 0x02, "Echo message"},
57    { 0x03, "Flush message"},
58    { 0, NULL}
59};
60
61static const struct tok udld_flags_values[] = {
62    { 0x00, "RT"},
63    { 0x01, "RSY"},
64    { 0, NULL}
65};
66
67/*
68 * UDLD's Protocol Data Unit format:
69 *
70 *  0                   1                   2                   3
71 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
72 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
73 * | Ver | Opcode  |     Flags     |           Checksum            |
74 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
75 * |               List of TLVs (variable length list)             |
76 * |                              ...                              |
77 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
78 *
79 * TLV format:
80 *
81 *  0                   1                   2                   3
82 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
83 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
84 * |             TYPE              |            LENGTH             |
85 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
86 * |                             VALUE                             |
87 * |                              ...                              |
88 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
89 *
90 * LENGTH: Length in bytes of the Type, Length, and Value fields.
91 */
92
93#define	UDLD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
94#define	UDLD_EXTRACT_OPCODE(x) ((x)&0x1f)
95
96void
97udld_print (netdissect_options *ndo, const u_char *pptr, u_int length)
98{
99    int code, type, len;
100    const u_char *tptr;
101
102    if (length < UDLD_HEADER_LEN)
103        goto trunc;
104
105    tptr = pptr;
106
107    ND_TCHECK2(*tptr, UDLD_HEADER_LEN);
108
109    code = UDLD_EXTRACT_OPCODE(*tptr);
110
111    ND_PRINT((ndo, "UDLDv%u, Code %s (%x), Flags [%s] (0x%02x), length %u",
112           UDLD_EXTRACT_VERSION(*tptr),
113           tok2str(udld_code_values, "Reserved", code),
114           code,
115           bittok2str(udld_flags_values, "none", *(tptr+1)),
116           *(tptr+1),
117           length));
118
119    /*
120     * In non-verbose mode, just print version and opcode type
121     */
122    if (ndo->ndo_vflag < 1) {
123	return;
124    }
125
126    ND_PRINT((ndo, "\n\tChecksum 0x%04x (unverified)", EXTRACT_16BITS(tptr+2)));
127
128    tptr += UDLD_HEADER_LEN;
129
130    while (tptr < (pptr+length)) {
131
132        ND_TCHECK2(*tptr, 4);
133	type = EXTRACT_16BITS(tptr);
134        len  = EXTRACT_16BITS(tptr+2);
135
136        ND_PRINT((ndo, "\n\t%s (0x%04x) TLV, length %u",
137               tok2str(udld_tlv_values, "Unknown", type),
138               type, len));
139
140        if (type == 0)
141            goto invalid;
142
143        /* infinite loop check */
144        if (len <= 4)
145            goto invalid;
146
147        len -= 4;
148        tptr += 4;
149
150        ND_TCHECK2(*tptr, len);
151
152        switch (type) {
153        case UDLD_DEVICE_ID_TLV:
154        case UDLD_PORT_ID_TLV:
155        case UDLD_DEVICE_NAME_TLV:
156            ND_PRINT((ndo, ", "));
157            fn_printzp(ndo, tptr, len, NULL);
158            break;
159
160        case UDLD_ECHO_TLV:
161            ND_PRINT((ndo, ", "));
162            (void)fn_printn(ndo, tptr, len, NULL);
163            break;
164
165        case UDLD_MESSAGE_INTERVAL_TLV:
166        case UDLD_TIMEOUT_INTERVAL_TLV:
167            if (len != 1)
168                goto invalid;
169            ND_PRINT((ndo, ", %us", (*tptr)));
170            break;
171
172        case UDLD_SEQ_NUMBER_TLV:
173            if (len != 4)
174                goto invalid;
175            ND_PRINT((ndo, ", %u", EXTRACT_32BITS(tptr)));
176            break;
177
178        default:
179            break;
180        }
181        tptr += len;
182    }
183
184    return;
185
186invalid:
187    ND_PRINT((ndo, "%s", istr));
188    return;
189trunc:
190    ND_PRINT((ndo, "%s", tstr));
191}
192
193/*
194 * Local Variables:
195 * c-style: whitesmith
196 * c-basic-offset: 4
197 * End:
198 */
199