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 #include <sys/cdefs.h>
23 #ifndef lint
24 __RCSID("$NetBSD: print-udld.c,v 1.5 2024/09/02 16:15:33 christos Exp $");
25 #endif
26
27 #include <config.h>
28
29 #include "netdissect-stdinc.h"
30
31 #define ND_LONGJMP_FROM_TCHECK
32 #include "netdissect.h"
33 #include "extract.h"
34
35
36 #define UDLD_HEADER_LEN 4
37 #define UDLD_TLV_HEADER_LEN 4
38 #define UDLD_DEVICE_ID_TLV 0x0001
39 #define UDLD_PORT_ID_TLV 0x0002
40 #define UDLD_ECHO_TLV 0x0003
41 #define UDLD_MESSAGE_INTERVAL_TLV 0x0004
42 #define UDLD_TIMEOUT_INTERVAL_TLV 0x0005
43 #define UDLD_DEVICE_NAME_TLV 0x0006
44 #define UDLD_SEQ_NUMBER_TLV 0x0007
45
46 static const struct tok udld_tlv_values[] = {
47 { UDLD_DEVICE_ID_TLV, "Device-ID TLV"},
48 { UDLD_PORT_ID_TLV, "Port-ID TLV"},
49 { UDLD_ECHO_TLV, "Echo TLV"},
50 { UDLD_MESSAGE_INTERVAL_TLV, "Message Interval TLV"},
51 { UDLD_TIMEOUT_INTERVAL_TLV, "Timeout Interval TLV"},
52 { UDLD_DEVICE_NAME_TLV, "Device Name TLV"},
53 { UDLD_SEQ_NUMBER_TLV,"Sequence Number TLV"},
54 { 0, NULL}
55 };
56
57 static const struct tok udld_code_values[] = {
58 { 0x00, "Reserved"},
59 { 0x01, "Probe message"},
60 { 0x02, "Echo message"},
61 { 0x03, "Flush message"},
62 { 0, NULL}
63 };
64
65 static const struct tok udld_flags_bitmap_str[] = {
66 { 1U << 0, "RT" },
67 { 1U << 1, "RSY" },
68 { 1U << 2, "MBZ-2" },
69 { 1U << 3, "MBZ-3" },
70 { 1U << 4, "MBZ-4" },
71 { 1U << 5, "MBZ-5" },
72 { 1U << 6, "MBZ-6" },
73 { 1U << 7, "MBZ-7" },
74 { 0, NULL}
75 };
76
77 /*
78 * UDLD's Protocol Data Unit format:
79 *
80 * 0 1 2 3
81 * 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
82 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
83 * | Ver | Opcode | Flags | Checksum |
84 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
85 * | List of TLVs (variable length list) |
86 * | ... |
87 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
88 *
89 * TLV format:
90 *
91 * 0 1 2 3
92 * 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
93 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
94 * | TYPE | LENGTH |
95 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
96 * | VALUE |
97 * | ... |
98 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
99 *
100 * LENGTH: Length in bytes of the Type, Length, and Value fields.
101 */
102
103 #define UDLD_EXTRACT_VERSION(x) (((x)&0xe0)>>5)
104 #define UDLD_EXTRACT_OPCODE(x) ((x)&0x1f)
105
106 void
udld_print(netdissect_options * ndo,const u_char * tptr,u_int length)107 udld_print(netdissect_options *ndo,
108 const u_char *tptr, u_int length)
109 {
110 uint8_t ver, code, flags;
111
112 ndo->ndo_protocol = "udld";
113 if (length < UDLD_HEADER_LEN)
114 goto invalid;
115
116 ver = UDLD_EXTRACT_VERSION(GET_U_1(tptr));
117 code = UDLD_EXTRACT_OPCODE(GET_U_1(tptr));
118 tptr += 1;
119 length -= 1;
120
121 flags = GET_U_1(tptr);
122 tptr += 1;
123 length -= 1;
124
125 ND_PRINT("UDLDv%u, Code %s (%x), Flags [%s] (0x%02x), length %u",
126 ver,
127 tok2str(udld_code_values, "Reserved", code),
128 code,
129 bittok2str(udld_flags_bitmap_str, "none", flags),
130 flags,
131 length + 2);
132
133 /*
134 * In non-verbose mode, just print version and opcode type
135 */
136 if (ndo->ndo_vflag < 1) {
137 goto tcheck_remainder;
138 }
139
140 ND_PRINT("\n\tChecksum 0x%04x (unverified)", GET_BE_U_2(tptr));
141 tptr += 2;
142 length -= 2;
143
144 while (length) {
145 uint16_t type, len;
146
147 if (length < UDLD_TLV_HEADER_LEN)
148 goto invalid;
149
150 type = GET_BE_U_2(tptr);
151 tptr += 2;
152 length -= 2;
153
154 len = GET_BE_U_2(tptr);
155 tptr += 2;
156 length -= 2;
157
158 ND_PRINT("\n\t%s (0x%04x) TLV, length %u",
159 tok2str(udld_tlv_values, "Unknown", type),
160 type, len);
161
162 /* infinite loop check */
163 if (len <= UDLD_TLV_HEADER_LEN)
164 goto invalid;
165
166 len -= UDLD_TLV_HEADER_LEN;
167 if (length < len)
168 goto invalid;
169
170 switch (type) {
171 case UDLD_DEVICE_ID_TLV:
172 case UDLD_PORT_ID_TLV:
173 case UDLD_DEVICE_NAME_TLV:
174 ND_PRINT(", ");
175 nd_printjnp(ndo, tptr, len);
176 break;
177
178 case UDLD_ECHO_TLV:
179 ND_PRINT(", ");
180 (void)nd_printn(ndo, tptr, len, NULL);
181 break;
182
183 case UDLD_MESSAGE_INTERVAL_TLV:
184 case UDLD_TIMEOUT_INTERVAL_TLV:
185 if (len != 1)
186 goto invalid;
187 ND_PRINT(", %us", (GET_U_1(tptr)));
188 break;
189
190 case UDLD_SEQ_NUMBER_TLV:
191 if (len != 4)
192 goto invalid;
193 ND_PRINT(", %u", GET_BE_U_4(tptr));
194 break;
195
196 default:
197 ND_TCHECK_LEN(tptr, len);
198 break;
199 }
200 tptr += len;
201 length -= len;
202 }
203
204 return;
205
206 invalid:
207 nd_print_invalid(ndo);
208 tcheck_remainder:
209 ND_TCHECK_LEN(tptr, length);
210 }
211