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