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 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