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