epan/dissectors/packet-m2tp.c

   1 /* packet-m2tp.c
   2  * Routines for M2TP User Adaptation Layer dissection
   3  * M2TP - MTP2 Transparent Proxy - is a Radisys proprietary
   4  * protocol based on the IETF SIGTRAN standard
   5  *
   6  * Copyright 2001, Heinz Prantner <heinz.prantner[AT]radisys.com>
   7  *
   8  * Wireshark - Network traffic analyzer
   9  * By Gerald Combs <gerald@wireshark.org>
  10  * Copyright 1998 Gerald Combs
  11  *
  12  * Copied from packet-m3ua.c
  13  * Thanks to Michael Tuexen for his valuable improvements
  14  *
  15  * SPDX-License-Identifier: GPL-2.0-or-later
  16  */
  17
  18 #include "config.h"
  19
  20 #include <epan/packet.h>
  21
  22 #include <wsutil/str_util.h>
  23
  24 #define M2TP_PAYLOAD_PROTOCOL_ID                       99    /* s-link, not IANA-registered */
  25
  26 void proto_register_m2tp(void);
  27 void proto_reg_handoff_m2tp(void);
  28
  29 static dissector_handle_t m2tp_handle;
  30
  31 #define SCTP_PORT_M2TP        9908  /* unassigned port number (not assigned by IANA) */
  32
  33 #define VERSION_LENGTH         1
  34 #define RESERVED_LENGTH        1
  35 #define MESSAGE_CLASS_LENGTH   1
  36 #define MESSAGE_TYPE_LENGTH    1
  37 #define MESSAGE_LENGTH_LENGTH  4
  38 #define COMMON_HEADER_LENGTH   (VERSION_LENGTH + RESERVED_LENGTH + MESSAGE_CLASS_LENGTH + \
  39                                 MESSAGE_TYPE_LENGTH + MESSAGE_LENGTH_LENGTH)
  40
  41 #define VERSION_OFFSET         0
  42 #define RESERVED_OFFSET        (VERSION_OFFSET + VERSION_LENGTH)
  43 #define MESSAGE_CLASS_OFFSET   (RESERVED_OFFSET + RESERVED_LENGTH)
  44 #define MESSAGE_TYPE_OFFSET    (MESSAGE_CLASS_OFFSET + MESSAGE_CLASS_LENGTH)
  45 #define MESSAGE_LENGTH_OFFSET  (MESSAGE_TYPE_OFFSET + MESSAGE_TYPE_LENGTH)
  46
  47 #define PARAMETER_TAG_LENGTH    2
  48 #define PARAMETER_LENGTH_LENGTH 2
  49 #define PARAMETER_HEADER_LENGTH (PARAMETER_TAG_LENGTH + PARAMETER_LENGTH_LENGTH)
  50
  51 #define PARAMETER_TAG_OFFSET      0
  52 #define PARAMETER_LENGTH_OFFSET   (PARAMETER_TAG_OFFSET + PARAMETER_TAG_LENGTH)
  53 #define PARAMETER_VALUE_OFFSET    (PARAMETER_LENGTH_OFFSET + PARAMETER_LENGTH_LENGTH)
  54 #define PARAMETER_HEADER_OFFSET   PARAMETER_TAG_OFFSET
  55
  56 #define INTERFACE_IDENTIFIER_PARAMETER_TAG     1
  57 #define MASTER_SLAVE_INDICATOR_PARAMETER_TAG   2
  58 #define M2TP_USER_IDENTIFIER_PARAMETER_TAG     3
  59 #define INFO_PARAMETER_TAG                     4
  60 #define DIAGNOSTIC_INFORMATION_PARAMETER_TAG   7
  61 #define HEARTBEAT_DATA_PARAMETER_TAG           9
  62 #define REASON_PARAMETER_TAG                  10
  63 #define ERROR_CODE_PARAMETER_TAG              12
  64 #define PROTOCOL_DATA_PARAMETER_TAG           13
  65
  66
  67 static const value_string m2tp_parameter_tag_values[] = {
  68   { INTERFACE_IDENTIFIER_PARAMETER_TAG,         "Interface Identifier" },
  69   { MASTER_SLAVE_INDICATOR_PARAMETER_TAG,       "Master Slave Indicator" },
  70   { M2TP_USER_IDENTIFIER_PARAMETER_TAG,         "M2tp User Identifier" },
  71   { INFO_PARAMETER_TAG,                         "Info" },
  72   { DIAGNOSTIC_INFORMATION_PARAMETER_TAG,       "Diagnostic Information" },
  73   { HEARTBEAT_DATA_PARAMETER_TAG,               "Heartbeat Data" },
  74   { REASON_PARAMETER_TAG,                       "Reason" },
  75   { ERROR_CODE_PARAMETER_TAG,                   "Error Code" },
  76   { PROTOCOL_DATA_PARAMETER_TAG,                "Protocol Data" },
  77   { 0,                           NULL } };
  78
  79 #define PROTOCOL_VERSION_RELEASE_1             1
  80
  81 static const value_string m2tp_protocol_version_values[] = {
  82   { PROTOCOL_VERSION_RELEASE_1,  "Release 1" },
  83   { 0,                           NULL } };
  84
  85 #define MESSAGE_CLASS_MGMT_MESSAGE        0
  86 #define MESSAGE_CLASS_SGSM_MESSAGE        3
  87 #define MESSAGE_CLASS_MAUP_MESSAGE        6
  88 #define MESSAGE_CLASS_DATA_MESSAGE        255
  89
  90 static const value_string m2tp_message_class_values[] = {
  91   { MESSAGE_CLASS_MGMT_MESSAGE,   "Management Messages" },
  92   { MESSAGE_CLASS_SGSM_MESSAGE,   "SG State Maintenance Messages" },
  93   { MESSAGE_CLASS_MAUP_MESSAGE,   "MTP2 User Adaptation Messages" },
  94   { MESSAGE_CLASS_DATA_MESSAGE,   "User Data Messages" },
  95   { 0,                            NULL } };
  96
  97 /* management messages */
  98 #define MESSAGE_TYPE_ERR                  0
  99
 100 /* sg state maintenance messages */
 101 #define MESSAGE_TYPE_UP                   1
 102 #define MESSAGE_TYPE_DOWN                 2
 103 #define MESSAGE_TYPE_BEAT                 3
 104 #define MESSAGE_TYPE_UP_ACK               4
 105 #define MESSAGE_TYPE_DOWN_ACK             5
 106 #define MESSAGE_TYPE_BEAT_ACK             6
 107
 108 /* mtp2 user message */
 109 #define MESSAGE_TYPE_DATA                 1
 110
 111
 112 static const value_string m2tp_message_class_type_values[] = {
 113   { MESSAGE_CLASS_MGMT_MESSAGE  * 256 + MESSAGE_TYPE_ERR,           "Error (ERR)" },
 114   { MESSAGE_CLASS_DATA_MESSAGE  * 256 + MESSAGE_TYPE_DATA,          "Payload data (DATA)" },
 115   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP,            "ASP up (UP)" },
 116   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN,          "ASP down (DOWN)" },
 117   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT,          "Heartbeat (BEAT)" },
 118   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP_ACK,        "ASP up ack (UP ACK)" },
 119   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN_ACK,      "ASP down ack (DOWN ACK)" },
 120   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT_ACK,      "Heartbeat ack (BEAT ACK)" },
 121   { 0,                           NULL } };
 122
 123 static const value_string m2tp_message_class_type_acro_values[] = {
 124   { MESSAGE_CLASS_MGMT_MESSAGE  * 256 + MESSAGE_TYPE_ERR,           "ERR" },
 125   { MESSAGE_CLASS_DATA_MESSAGE  * 256 + MESSAGE_TYPE_DATA,          "DATA" },
 126   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP,            "ASP_UP" },
 127   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN,          "ASP_DOWN" },
 128   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT,          "BEAT" },
 129   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP_ACK,        "ASP_UP_ACK" },
 130   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN_ACK,      "ASP_DOWN_ACK" },
 131   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT_ACK,      "BEAT_ACK" },
 132   { 0,                           NULL } };
 133
 134
 135
 136 #define HEARTBEAT_PERIOD_OFFSET PARAMETER_VALUE_OFFSET
 137
 138 #define INTERFACE_IDENTIFIER_LENGTH 4
 139 #define INTERFACE_IDENTIFIER_OFFSET PARAMETER_VALUE_OFFSET
 140
 141 #define M2TP_USER_LENGTH 4
 142 #define M2TP_USER_OFFSET PARAMETER_VALUE_OFFSET
 143
 144 #define PROTOCOL_DATA_OFFSET PARAMETER_VALUE_OFFSET
 145
 146 #define MASTER_SLAVE_LENGTH 4
 147 #define MASTER_SLAVE_OFFSET PARAMETER_VALUE_OFFSET
 148
 149 #define REASON_LENGTH 4
 150 #define REASON_OFFSET PARAMETER_VALUE_OFFSET
 151
 152 #define HEART_BEAT_DATA_OFFSET PARAMETER_VALUE_OFFSET
 153
 154 #define ERROR_CODE_LENGTH 4
 155 #define ERROR_CODE_OFFSET PARAMETER_VALUE_OFFSET
 156
 157 #define INFO_STRING_OFFSET PARAMETER_VALUE_OFFSET
 158
 159 #define BSN_OFFSET PARAMETER_VALUE_OFFSET
 160 #define FSN_OFFSET PARAMETER_VALUE_OFFSET+1
 161
 162 #define M2TP_USER_MTP2          1
 163 #define M2TP_USER_Q921          2
 164 #define M2TP_USER_FRAME_RELAY   3
 165
 166 static const value_string m2tp_user_identifier_values[] = {
 167   { M2TP_USER_MTP2,        "MTP2" },
 168   { M2TP_USER_Q921,        "Q.921" },
 169   { M2TP_USER_FRAME_RELAY, "Frame Relay" },
 170   { 0, NULL }};
 171
 172 #define M2TP_MODE_MASTER 1
 173 #define M2TP_MODE_SLAVE  2
 174
 175 static const value_string m2tp_mode_values[] = {
 176   { M2TP_MODE_MASTER,      "Master" },
 177   { M2TP_MODE_SLAVE,       "Slave" },
 178   { 0, NULL}};
 179
 180 #define M2TP_ERROR_CODE_INVALID_VERSION                         1
 181 #define M2TP_ERROR_CODE_INVALID_INTERFACE_IDENTIFIER            2
 182 #define M2TP_ERROR_CODE_INVALID_ADAPTATION_LAYER_IDENTIFIER     3
 183 #define M2TP_ERROR_CODE_INVALID_MESSAGE_TYPE                    4
 184 #define M2TP_ERROR_CODE_INVALID_TRAFFIC_HANDLING_MODE           5
 185 #define M2TP_ERROR_CODE_UNEXPECTED_MESSAGE                      6
 186 #define M2TP_ERROR_CODE_PROTOCOL_ERROR                          7
 187 #define M2TP_ERROR_CODE_INVALID_STREAM_IDENTIFIER               8
 188 #define M2TP_ERROR_CODE_INCOMPATIBLE_MASTER_SLAVE_CONFIGURATION 9
 189
 190 static const value_string m2tp_error_code_values[] = {
 191   { M2TP_ERROR_CODE_INVALID_VERSION,                        "Invalid Version" },
 192   { M2TP_ERROR_CODE_INVALID_INTERFACE_IDENTIFIER,           "Invalid Interface Identifier" },
 193   { M2TP_ERROR_CODE_INVALID_ADAPTATION_LAYER_IDENTIFIER,    "Invalid Adaptation Layer Identifier" },
 194   { M2TP_ERROR_CODE_INVALID_MESSAGE_TYPE,                   "Invalid Message Type" },
 195   { M2TP_ERROR_CODE_INVALID_TRAFFIC_HANDLING_MODE,          "Invalid Traffic Handling Mode" },
 196   { M2TP_ERROR_CODE_UNEXPECTED_MESSAGE,                     "Unexpected Message" },
 197   { M2TP_ERROR_CODE_PROTOCOL_ERROR,                         "Protocol Error" },
 198   { M2TP_ERROR_CODE_INVALID_STREAM_IDENTIFIER,              "Invalid Stream Identified" },
 199   { M2TP_ERROR_CODE_INCOMPATIBLE_MASTER_SLAVE_CONFIGURATION,"Incompatible Master Slave Configuration" },
 200   { 0,                                                      NULL } };
 201
 202 #define MANAGEMENT_ORDER_REASON_CODE       1
 203 #define MTP_RELEASE_REASON_CODE            2
 204
 205 static const value_string m2tp_reason_code_values[] = {
 206   { MANAGEMENT_ORDER_REASON_CODE,                      "Management Order" },
 207   { MTP_RELEASE_REASON_CODE,                           "MTP Release" },
 208   { 0,                                                 NULL } };
 209
 210
 211 /* Initialize the protocol and registered fields */
 212 static int proto_m2tp;
 213 static int hf_m2tp_version;
 214 static int hf_m2tp_reserved;
 215 static int hf_m2tp_message_class;
 216 static int hf_m2tp_message_type;
 217 static int hf_m2tp_message_length;
 218 static int hf_m2tp_parameter_tag;
 219 static int hf_m2tp_parameter_length;
 220 static int hf_m2tp_parameter_value;
 221 static int hf_m2tp_parameter_padding;
 222 static int hf_m2tp_interface_identifier;
 223 static int hf_m2tp_user;
 224 static int hf_m2tp_master_slave;
 225 static int hf_m2tp_info_string;
 226 static int hf_m2tp_heartbeat_data;
 227 static int hf_m2tp_diagnostic_info;
 228 static int hf_m2tp_error_code;
 229 static int hf_m2tp_reason;
 230
 231 /* Initialize the subtree pointers */
 232 static int ett_m2tp;
 233 static int ett_m2tp_parameter;
 234
 235 static dissector_handle_t mtp2_handle;
 236
 237 static unsigned
 238 nr_of_padding_bytes (unsigned length)
 239 {
 240   unsigned remainder;
 241
 242   remainder = length % 4;
 243
 244   if (remainder == 0)
 245     return 0;
 246   else
 247     return 4 - remainder;
 248 }
 249
 250 /* Common Header */
 251 static void
 252 dissect_m2tp_common_header(tvbuff_t *common_header_tvb, packet_info *pinfo, proto_tree *m2tp_tree)
 253 {
 254   uint8_t version, reserved, message_class, message_type;
 255   uint32_t message_length;
 256
 257   /* Extract the common header */
 258   version        = tvb_get_uint8(common_header_tvb, VERSION_OFFSET);
 259   reserved       = tvb_get_uint8(common_header_tvb, RESERVED_OFFSET);
 260   message_class  = tvb_get_uint8(common_header_tvb, MESSAGE_CLASS_OFFSET);
 261   message_type   = tvb_get_uint8(common_header_tvb, MESSAGE_TYPE_OFFSET);
 262   message_length = tvb_get_ntohl (common_header_tvb, MESSAGE_LENGTH_OFFSET);
 263
 264   col_add_fstr(pinfo->cinfo, COL_INFO, "%s ", val_to_str_const(message_class * 256 + message_type, m2tp_message_class_type_acro_values, "reserved"));
 265
 266   if (m2tp_tree) {
 267     /* add the components of the common header to the protocol tree */
 268     proto_tree_add_uint(m2tp_tree, hf_m2tp_version, common_header_tvb, VERSION_OFFSET, VERSION_LENGTH, version);
 269     proto_tree_add_uint(m2tp_tree, hf_m2tp_reserved, common_header_tvb, RESERVED_OFFSET, RESERVED_LENGTH, reserved);
 270     proto_tree_add_uint(m2tp_tree, hf_m2tp_message_class, common_header_tvb, MESSAGE_CLASS_OFFSET, MESSAGE_CLASS_LENGTH, message_class);
 271     proto_tree_add_uint_format_value(m2tp_tree, hf_m2tp_message_type,
 272                                common_header_tvb, MESSAGE_TYPE_OFFSET, MESSAGE_TYPE_LENGTH,
 273                                message_type, "%u (%s)",
 274                                message_type, val_to_str_const(message_class * 256 + message_type, m2tp_message_class_type_values, "reserved"));
 275     proto_tree_add_uint(m2tp_tree, hf_m2tp_message_length, common_header_tvb, MESSAGE_LENGTH_OFFSET, MESSAGE_LENGTH_LENGTH, message_length);
 276   };
 277 }
 278
 279 /* Interface Identifier */
 280 static void
 281 dissect_m2tp_interface_identifier_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo _U_, proto_tree *parameter_tree, proto_item *parameter_item)
 282 {
 283   uint32_t parameter_value;
 284
 285   if (parameter_tree) {
 286     parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
 287     proto_tree_add_uint(parameter_tree, hf_m2tp_interface_identifier, parameter_tvb, INTERFACE_IDENTIFIER_OFFSET, INTERFACE_IDENTIFIER_LENGTH, parameter_value);
 288     proto_item_set_text(parameter_item, "Interface Identifier (%u)", parameter_value);
 289   }
 290 }
 291
 292 /* Master Slave Indicator */
 293 static void
 294 dissect_m2tp_master_slave_parameter (tvbuff_t *parameter_tvb, packet_info *pinfo _U_, proto_tree *parameter_tree, proto_item *parameter_item)
 295 {
 296   uint32_t parameter_value;
 297
 298   if (parameter_tree) {
 299     parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
 300     proto_tree_add_uint(parameter_tree, hf_m2tp_master_slave, parameter_tvb, MASTER_SLAVE_OFFSET, MASTER_SLAVE_LENGTH, parameter_value);
 301     proto_item_set_text(parameter_item, "Master Slave Indicator (%s)", val_to_str_const(parameter_value, m2tp_mode_values, "unknown"));
 302   }
 303 }
 304
 305 /* M2tp User Identifier */
 306 static void
 307 dissect_m2tp_user_identifier_parameter (tvbuff_t *parameter_tvb, packet_info *pinfo _U_, proto_tree *parameter_tree, proto_item *parameter_item)
 308 {
 309   uint32_t parameter_value;
 310
 311   if (parameter_tree) {
 312     parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
 313     proto_tree_add_uint(parameter_tree, hf_m2tp_user, parameter_tvb, M2TP_USER_OFFSET, M2TP_USER_LENGTH, parameter_value);
 314     proto_item_set_text(parameter_item, "M2TP User Identifier (%u)", parameter_value);
 315   }
 316 }
 317
 318 /* Info String */
 319 static void
 320 dissect_m2tp_info_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo, proto_tree *parameter_tree, proto_item *parameter_item)
 321 {
 322   uint16_t length, info_string_length;
 323   const uint8_t *info_string;
 324
 325   if (parameter_tree) {
 326     length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 327     info_string_length = length - PARAMETER_HEADER_LENGTH;
 328     proto_tree_add_item_ret_string(parameter_tree, hf_m2tp_info_string, parameter_tvb, INFO_STRING_OFFSET, info_string_length, ENC_ASCII, pinfo->pool, &info_string);
 329     proto_item_set_text(parameter_item, "Info String (%s)", info_string);
 330   }
 331 }
 332
 333 /* Diagnostic Information */
 334 static void
 335 dissect_m2tp_diagnostic_information_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo _U_, proto_tree *parameter_tree, proto_item *parameter_item)
 336 {
 337   uint16_t length, diagnostic_info_length;
 338
 339   if (parameter_tree) {
 340     length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 341     diagnostic_info_length = length - PARAMETER_HEADER_LENGTH;
 342     proto_tree_add_item(parameter_tree, hf_m2tp_diagnostic_info, parameter_tvb, PARAMETER_VALUE_OFFSET, diagnostic_info_length, ENC_NA);
 343     proto_item_set_text(parameter_item, "Diagnostic information (%u byte%s)", diagnostic_info_length, plurality(diagnostic_info_length, "", "s"));
 344   }
 345 }
 346
 347 /* Heartbeat Data */
 348 static void
 349 dissect_m2tp_heartbeat_data_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo _U_, proto_tree *parameter_tree, proto_item *parameter_item)
 350 {
 351   uint16_t length, heartbeat_data_length;
 352
 353   if (parameter_tree) {
 354     length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 355     heartbeat_data_length = length - PARAMETER_HEADER_LENGTH;
 356     proto_tree_add_item(parameter_tree, hf_m2tp_heartbeat_data, parameter_tvb, PARAMETER_VALUE_OFFSET, heartbeat_data_length, ENC_NA);
 357     proto_item_set_text(parameter_item, "Heartbeat data (%u byte%s)", heartbeat_data_length, plurality(heartbeat_data_length, "", "s"));
 358   }
 359 }
 360
 361 /* Reason Parameter */
 362 static void
 363 dissect_m2tp_reason_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo _U_, proto_tree *parameter_tree, proto_item *parameter_item)
 364 {
 365   uint32_t reason;
 366
 367   if (parameter_tree) {
 368     reason = tvb_get_ntohl(parameter_tvb, REASON_OFFSET);
 369     proto_tree_add_uint(parameter_tree, hf_m2tp_reason, parameter_tvb, REASON_OFFSET, REASON_LENGTH, reason);
 370     proto_item_set_text(parameter_item, "Reason parameter (%s)", val_to_str_const(reason, m2tp_reason_code_values, "unknown"));
 371   }
 372 }
 373
 374 /* Error Code */
 375 static void
 376 dissect_m2tp_error_code_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo _U_, proto_tree *parameter_tree, proto_item *parameter_item)
 377 {
 378   uint32_t error_code;
 379
 380   if (parameter_tree) {
 381     error_code = tvb_get_ntohl(parameter_tvb, ERROR_CODE_OFFSET);
 382     proto_tree_add_uint(parameter_tree, hf_m2tp_error_code, parameter_tvb, ERROR_CODE_OFFSET, ERROR_CODE_LENGTH, error_code);
 383     proto_item_set_text(parameter_item, "Error code parameter (%s)", val_to_str_const(error_code, m2tp_error_code_values, "unknown"));
 384   }
 385 }
 386
 387 /* Protocol Data */
 388 static void
 389 dissect_m2tp_protocol_data_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo, proto_tree *parameter_tree, proto_item *parameter_item, proto_item *m2tp_item, proto_tree *tree)
 390 {
 391   uint16_t length, protocol_data_length, padding_length;
 392   tvbuff_t *mtp2_tvb;
 393
 394   length               = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 395   padding_length       = nr_of_padding_bytes(length);
 396   protocol_data_length = length - PARAMETER_HEADER_LENGTH;
 397
 398   mtp2_tvb = tvb_new_subset_length(parameter_tvb, PARAMETER_VALUE_OFFSET, protocol_data_length);
 399   call_dissector(mtp2_handle, mtp2_tvb, pinfo, tree);
 400
 401   if (parameter_tree) {
 402     proto_item_set_text(parameter_item, "Protocol data (SS7 message)");
 403     proto_item_set_len(parameter_item, proto_item_get_len(parameter_item) - protocol_data_length - padding_length);
 404     proto_item_set_len(m2tp_item,      proto_item_get_len(m2tp_item)      - protocol_data_length - padding_length);
 405
 406   }
 407 }
 408
 409 /* Unknown Parameter */
 410 static void
 411 dissect_m2tp_unknown_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo _U_, proto_tree *parameter_tree, proto_item *parameter_item)
 412 {
 413   uint16_t tag, length, parameter_value_length;
 414
 415   if (parameter_tree) {
 416     tag    = tvb_get_ntohs(parameter_tvb, PARAMETER_TAG_OFFSET);
 417     length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 418
 419     parameter_value_length = length - PARAMETER_HEADER_LENGTH;
 420     proto_tree_add_item(parameter_tree, hf_m2tp_parameter_value, parameter_tvb, PARAMETER_VALUE_OFFSET, parameter_value_length, ENC_NA);
 421
 422     proto_item_set_text(parameter_item, "Parameter with tag %u and %u byte%s value", tag, parameter_value_length, plurality(parameter_value_length, "", "s"));
 423   }
 424 }
 425
 426 /* M2TP Parameter */
 427 static void
 428 dissect_m2tp_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo, proto_tree *m2tp_tree, proto_item *m2tp_item, proto_tree *tree)
 429 {
 430   uint16_t tag, length, padding_length, total_length;
 431   proto_item *parameter_item = NULL;
 432   proto_tree *parameter_tree = NULL;
 433
 434   /* extract tag and length from the parameter */
 435   tag            = tvb_get_ntohs(parameter_tvb, PARAMETER_TAG_OFFSET);
 436   length         = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 437
 438   /* calculate padding and total length */
 439   padding_length = nr_of_padding_bytes(length);
 440   total_length   = length + padding_length;
 441
 442   if (tree) {
 443     /* create proto_tree stuff */
 444     parameter_tree = proto_tree_add_subtree(m2tp_tree, parameter_tvb, PARAMETER_HEADER_OFFSET, total_length,
 445                                         ett_m2tp_parameter, &parameter_item, "Incomplete parameter");
 446
 447     /* add tag and length to the m2tp tree */
 448     proto_tree_add_uint(parameter_tree, hf_m2tp_parameter_tag, parameter_tvb, PARAMETER_TAG_OFFSET, PARAMETER_TAG_LENGTH, tag);
 449     proto_tree_add_uint(parameter_tree, hf_m2tp_parameter_length, parameter_tvb, PARAMETER_LENGTH_OFFSET, PARAMETER_LENGTH_LENGTH, length);
 450   }
 451
 452   switch(tag) {
 453     case INTERFACE_IDENTIFIER_PARAMETER_TAG:
 454       dissect_m2tp_interface_identifier_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 455       break;
 456     case MASTER_SLAVE_INDICATOR_PARAMETER_TAG:
 457       dissect_m2tp_master_slave_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 458       break;
 459     case M2TP_USER_IDENTIFIER_PARAMETER_TAG:
 460       dissect_m2tp_user_identifier_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 461       break;
 462     case INFO_PARAMETER_TAG:
 463       dissect_m2tp_info_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 464       break;
 465     case DIAGNOSTIC_INFORMATION_PARAMETER_TAG:
 466       dissect_m2tp_diagnostic_information_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 467       break;
 468     case HEARTBEAT_DATA_PARAMETER_TAG:
 469       dissect_m2tp_heartbeat_data_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 470       break;
 471     case REASON_PARAMETER_TAG:
 472       dissect_m2tp_reason_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 473       break;
 474     case ERROR_CODE_PARAMETER_TAG:
 475       dissect_m2tp_error_code_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 476       break;
 477     case PROTOCOL_DATA_PARAMETER_TAG:
 478       dissect_m2tp_protocol_data_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item, m2tp_item, tree);
 479       break;
 480     default:
 481       dissect_m2tp_unknown_parameter(parameter_tvb, pinfo, parameter_tree, parameter_item);
 482       break;
 483   };
 484
 485   if ((parameter_tree) && (padding_length > 0))
 486     proto_tree_add_item(parameter_tree, hf_m2tp_parameter_padding, parameter_tvb, PARAMETER_HEADER_OFFSET + length, padding_length, ENC_NA);
 487 }
 488
 489 /* M2TP Message */
 490 static void
 491 dissect_m2tp_message(tvbuff_t *message_tvb, packet_info *pinfo, proto_item *m2tp_item, proto_tree *m2tp_tree, proto_tree *tree)
 492 {
 493   int offset, length, padding_length, total_length;
 494   tvbuff_t *common_header_tvb, *parameter_tvb;
 495
 496   offset = 0;
 497
 498   /* extract and process the common header */
 499   common_header_tvb = tvb_new_subset_length(message_tvb, offset, COMMON_HEADER_LENGTH);
 500   dissect_m2tp_common_header(common_header_tvb, pinfo, m2tp_tree);
 501   offset += COMMON_HEADER_LENGTH;
 502
 503   /* extract zero or more parameters and process them individually */
 504   while(tvb_reported_length_remaining(message_tvb, offset) > 0) {
 505     length         = tvb_get_ntohs(message_tvb, offset + PARAMETER_LENGTH_OFFSET);
 506     padding_length = nr_of_padding_bytes(length);
 507     total_length   = length + padding_length;
 508     /* create a tvb for the parameter including the padding bytes */
 509     parameter_tvb    = tvb_new_subset_length(message_tvb, offset, total_length);
 510     dissect_m2tp_parameter(parameter_tvb, pinfo, m2tp_tree, m2tp_item, tree);
 511     /* get rid of the handled parameter */
 512     offset += total_length;
 513   }
 514 }
 515
 516 /* M2tp */
 517 static int
 518 dissect_m2tp(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
 519 {
 520   proto_item *m2tp_item;
 521   proto_tree *m2tp_tree;
 522
 523   /* make entry in the Protocol column on summary display */
 524   col_set_str(pinfo->cinfo, COL_PROTOCOL, "M2TP");
 525
 526   /* create the m2tp protocol tree */
 527   m2tp_item = proto_tree_add_item(tree, proto_m2tp, message_tvb, 0, -1, ENC_NA);
 528   m2tp_tree = proto_item_add_subtree(m2tp_item, ett_m2tp);
 529
 530   /* dissect the message */
 531   dissect_m2tp_message(message_tvb, pinfo, m2tp_item, m2tp_tree, tree);
 532   return tvb_captured_length(message_tvb);
 533 }
 534
 535 /* Register the protocol with Wireshark */
 536 void
 537 proto_register_m2tp(void)
 538 {
 539
 540   /* Setup list of header fields */
 541   static hf_register_info hf[] = {
 542     { &hf_m2tp_version,
 543       { "Version", "m2tp.version",
 544         FT_UINT8, BASE_DEC, VALS(m2tp_protocol_version_values), 0x0,
 545         NULL, HFILL}
 546     },
 547     { &hf_m2tp_reserved,
 548       { "Reserved", "m2tp.reserved",
 549         FT_UINT8, BASE_HEX, NULL, 0x0,
 550         NULL, HFILL}
 551     },
 552     { &hf_m2tp_message_class,
 553       { "Message class", "m2tp.message_class",
 554         FT_UINT8, BASE_DEC, VALS(m2tp_message_class_values), 0x0,
 555         NULL, HFILL}
 556     },
 557     { &hf_m2tp_message_type,
 558       { "Message Type", "m2tp.message_type",
 559         FT_UINT8, BASE_DEC, NULL, 0x0,
 560         NULL, HFILL}
 561     },
 562     { &hf_m2tp_message_length,
 563       { "Message length", "m2tp.message_length",
 564         FT_UINT32, BASE_DEC, NULL, 0x0,
 565         NULL, HFILL}
 566     },
 567     { &hf_m2tp_parameter_tag,
 568       { "Parameter Tag", "m2tp.parameter_tag",
 569         FT_UINT16, BASE_DEC, VALS(m2tp_parameter_tag_values), 0x0,
 570         NULL, HFILL}
 571     },
 572     { &hf_m2tp_parameter_length,
 573       { "Parameter length", "m2tp.parameter_length",
 574         FT_UINT16, BASE_DEC, NULL, 0x0,
 575         NULL, HFILL}
 576     },
 577     { &hf_m2tp_parameter_value,
 578       { "Parameter Value", "m2tp.parameter_value",
 579         FT_BYTES, BASE_NONE, NULL, 0x0,
 580         NULL, HFILL }
 581     },
 582     { &hf_m2tp_parameter_padding,
 583       { "Padding", "m2tp.parameter_padding",
 584         FT_BYTES, BASE_NONE, NULL, 0x0,
 585         NULL, HFILL }
 586     },
 587     { &hf_m2tp_interface_identifier,
 588       { "Interface Identifier", "m2tp.interface_identifier",
 589         FT_UINT32, BASE_DEC, NULL, 0x0,
 590         NULL, HFILL}
 591     },
 592     { &hf_m2tp_user,
 593       { "M2tp User Identifier", "m2tp.user_identifier",
 594         FT_UINT32, BASE_DEC, VALS(m2tp_user_identifier_values), 0x0,
 595         NULL, HFILL}
 596     },
 597     { &hf_m2tp_master_slave,
 598       { "Master Slave Indicator", "m2tp.master_slave",
 599         FT_UINT32, BASE_DEC, VALS(m2tp_mode_values), 0x0,
 600         NULL, HFILL}
 601     },
 602     { &hf_m2tp_info_string,
 603       { "Info string", "m2tp.info_string",
 604         FT_STRING, BASE_NONE, NULL, 0x0,
 605         NULL, HFILL}
 606     },
 607     { &hf_m2tp_diagnostic_info,
 608       { "Diagnostic information", "m2tp.diagnostic_info",
 609         FT_BYTES, BASE_NONE, NULL, 0x0,
 610         NULL, HFILL }
 611     },
 612     { &hf_m2tp_heartbeat_data,
 613       { "Heartbeat data", "m2tp.heartbeat_data",
 614         FT_BYTES, BASE_NONE, NULL, 0x0,
 615         NULL, HFILL }
 616     },
 617     { &hf_m2tp_error_code,
 618       { "Error code", "m2tp.error_code",
 619         FT_UINT32, BASE_DEC, VALS(m2tp_error_code_values), 0x0,
 620         NULL, HFILL}
 621     },
 622     { &hf_m2tp_reason,
 623       { "Reason", "m2tp.reason",
 624         FT_UINT32, BASE_DEC, NULL, 0x0,
 625         NULL, HFILL}
 626     },
 627   };
 628
 629   /* Setup protocol subtree array */
 630   static int *ett[] = {
 631     &ett_m2tp,
 632     &ett_m2tp_parameter,
 633   };
 634
 635   /* Register the protocol name and description */
 636   proto_m2tp = proto_register_protocol("MTP 2 Transparent Proxy", "M2TP",  "m2tp");
 637
 638   /* Required function calls to register the header fields and subtrees used */
 639   proto_register_field_array(proto_m2tp, hf, array_length(hf));
 640   proto_register_subtree_array(ett, array_length(ett));
 641
 642   /* Register the dissector */
 643   m2tp_handle = register_dissector("m2tp", dissect_m2tp, proto_m2tp);
 644 }
 645
 646 void
 647 proto_reg_handoff_m2tp(void)
 648 {
 649   mtp2_handle = find_dissector_add_dependency("mtp2", proto_m2tp);
 650   dissector_add_uint("sctp.ppi",  M2TP_PAYLOAD_PROTOCOL_ID, m2tp_handle);
 651   dissector_add_uint("sctp.port", SCTP_PORT_M2TP, m2tp_handle);
 652 }
 653
 654 /*
 655  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 656  *
 657  * Local Variables:
 658  * c-basic-offset: 2
 659  * tab-width: 8
 660  * indent-tabs-mode: nil
 661  * End:
 662  *
 663  * ex: set shiftwidth=2 tabstop=8 expandtab:
 664  * :indentSize=2:tabSize=8:noTabs=true:
 665  */