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  * $Id$
   9  *
  10  * Wireshark - Network traffic analyzer
  11  * By Gerald Combs <gerald@wireshark.org>
  12  * Copyright 1998 Gerald Combs
  13  *
  14  * Copied from packet-m3ua.c
  15  * Thanks to Michael Tuexen for his valuable improvements
  16  *
  17  * This program is free software; you can redistribute it and/or
  18  * modify it under the terms of the GNU General Public License
  19  * as published by the Free Software Foundation; either version 2
  20  * of the License, or (at your option) any later version.
  21  *
  22  * This program is distributed in the hope that it will be useful,
  23  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25  * GNU General Public License for more details.
  26  *
  27  * You should have received a copy of the GNU General Public License
  28  * along with this program; if not, write to the Free Software
  29  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  30  */
  31
  32 #include "config.h"
  33
  34 #include <glib.h>
  35
  36 #include <epan/packet.h>
  37 #include <epan/sctpppids.h>
  38
  39 #define SCTP_PORT_M2TP        9908  /* unassigned port number (not assigned by IANA) */
  40
  41 #define VERSION_LENGTH         1
  42 #define RESERVED_LENGTH        1
  43 #define MESSAGE_CLASS_LENGTH   1
  44 #define MESSAGE_TYPE_LENGTH    1
  45 #define MESSAGE_LENGTH_LENGTH  4
  46 #define COMMON_HEADER_LENGTH   (VERSION_LENGTH + RESERVED_LENGTH + MESSAGE_CLASS_LENGTH + \
  47                                 MESSAGE_TYPE_LENGTH + MESSAGE_LENGTH_LENGTH)
  48
  49 #define VERSION_OFFSET         0
  50 #define RESERVED_OFFSET        (VERSION_OFFSET + VERSION_LENGTH)
  51 #define MESSAGE_CLASS_OFFSET   (RESERVED_OFFSET + RESERVED_LENGTH)
  52 #define MESSAGE_TYPE_OFFSET    (MESSAGE_CLASS_OFFSET + MESSAGE_CLASS_LENGTH)
  53 #define MESSAGE_LENGTH_OFFSET  (MESSAGE_TYPE_OFFSET + MESSAGE_TYPE_LENGTH)
  54
  55 #define PARAMETER_TAG_LENGTH    2
  56 #define PARAMETER_LENGTH_LENGTH 2
  57 #define PARAMETER_HEADER_LENGTH (PARAMETER_TAG_LENGTH + PARAMETER_LENGTH_LENGTH)
  58
  59 #define PARAMETER_TAG_OFFSET      0
  60 #define PARAMETER_LENGTH_OFFSET   (PARAMETER_TAG_OFFSET + PARAMETER_TAG_LENGTH)
  61 #define PARAMETER_VALUE_OFFSET    (PARAMETER_LENGTH_OFFSET + PARAMETER_LENGTH_LENGTH)
  62 #define PARAMETER_HEADER_OFFSET   PARAMETER_TAG_OFFSET
  63
  64 #define INTERFACE_IDENTIFIER_PARAMETER_TAG     1
  65 #define MASTER_SLAVE_INDICATOR_PARAMETER_TAG   2
  66 #define M2TP_USER_IDENTIFIER_PARAMETER_TAG     3
  67 #define INFO_PARAMETER_TAG                     4
  68 #define DIAGNOSTIC_INFORMATION_PARAMETER_TAG   7
  69 #define HEARTBEAT_DATA_PARAMETER_TAG           9
  70 #define REASON_PARAMETER_TAG                  10
  71 #define ERROR_CODE_PARAMETER_TAG              12
  72 #define PROTOCOL_DATA_PARAMETER_TAG           13
  73
  74
  75 static const value_string m2tp_parameter_tag_values[] = {
  76   { INTERFACE_IDENTIFIER_PARAMETER_TAG,         "Interface Identifier" },
  77   { MASTER_SLAVE_INDICATOR_PARAMETER_TAG,       "Master Slave Indicator" },
  78   { M2TP_USER_IDENTIFIER_PARAMETER_TAG,         "M2tp User Identifier" },
  79   { INFO_PARAMETER_TAG,                         "Info" },
  80   { DIAGNOSTIC_INFORMATION_PARAMETER_TAG,       "Diagnostic Information" },
  81   { HEARTBEAT_DATA_PARAMETER_TAG,               "Heartbeat Data" },
  82   { REASON_PARAMETER_TAG,                       "Reason" },
  83   { ERROR_CODE_PARAMETER_TAG,                   "Error Code" },
  84   { PROTOCOL_DATA_PARAMETER_TAG,                "Protocol Data" },
  85   { 0,                           NULL } };
  86
  87 #define PROTOCOL_VERSION_RELEASE_1             1
  88
  89 static const value_string m2tp_protocol_version_values[] = {
  90   { PROTOCOL_VERSION_RELEASE_1,  "Release 1" },
  91   { 0,                           NULL } };
  92
  93 #define MESSAGE_CLASS_MGMT_MESSAGE        0
  94 #define MESSAGE_CLASS_SGSM_MESSAGE        3
  95 #define MESSAGE_CLASS_MAUP_MESSAGE        6
  96 #define MESSAGE_CLASS_DATA_MESSAGE        255
  97
  98 static const value_string m2tp_message_class_values[] = {
  99   { MESSAGE_CLASS_MGMT_MESSAGE,   "Management Messages" },
 100   { MESSAGE_CLASS_SGSM_MESSAGE,   "SG State Maintenance Messages" },
 101   { MESSAGE_CLASS_MAUP_MESSAGE,   "MTP2 User Adaptation Messages" },
 102   { MESSAGE_CLASS_DATA_MESSAGE,   "User Data Messages" },
 103   { 0,                            NULL } };
 104
 105 /* management messages */
 106 #define MESSAGE_TYPE_ERR                  0
 107
 108 /* sg state maintenance messages */
 109 #define MESSAGE_TYPE_UP                   1
 110 #define MESSAGE_TYPE_DOWN                 2
 111 #define MESSAGE_TYPE_BEAT                 3
 112 #define MESSAGE_TYPE_UP_ACK               4
 113 #define MESSAGE_TYPE_DOWN_ACK             5
 114 #define MESSAGE_TYPE_BEAT_ACK             6
 115
 116 /* mtp2 user message */
 117 #define MESSAGE_TYPE_DATA                 1
 118
 119
 120 static const value_string m2tp_message_class_type_values[] = {
 121   { MESSAGE_CLASS_MGMT_MESSAGE  * 256 + MESSAGE_TYPE_ERR,           "Error (ERR)" },
 122   { MESSAGE_CLASS_DATA_MESSAGE  * 256 + MESSAGE_TYPE_DATA,          "Payload data (DATA)" },
 123   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP,            "ASP up (UP)" },
 124   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN,          "ASP down (DOWN)" },
 125   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT,          "Heartbeat (BEAT)" },
 126   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP_ACK,        "ASP up ack (UP ACK)" },
 127   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN_ACK,      "ASP down ack (DOWN ACK)" },
 128   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT_ACK,      "Heartbeat ack (BEAT ACK)" },
 129   { 0,                           NULL } };
 130
 131 static const value_string m2tp_message_class_type_acro_values[] = {
 132   { MESSAGE_CLASS_MGMT_MESSAGE  * 256 + MESSAGE_TYPE_ERR,           "ERR" },
 133   { MESSAGE_CLASS_DATA_MESSAGE  * 256 + MESSAGE_TYPE_DATA,          "DATA" },
 134   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP,            "ASP_UP" },
 135   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN,          "ASP_DOWN" },
 136   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT,          "BEAT" },
 137   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP_ACK,        "ASP_UP_ACK" },
 138   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN_ACK,      "ASP_DOWN_ACK" },
 139   { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT_ACK,      "BEAT_ACK" },
 140   { 0,                           NULL } };
 141
 142
 143
 144 #define HEARTBEAT_PERIOD_OFFSET PARAMETER_VALUE_OFFSET
 145
 146 #define INTERFACE_IDENTIFIER_LENGTH 4
 147 #define INTERFACE_IDENTIFIER_OFFSET PARAMETER_VALUE_OFFSET
 148
 149 #define M2TP_USER_LENGTH 4
 150 #define M2TP_USER_OFFSET PARAMETER_VALUE_OFFSET
 151
 152 #define PROTOCOL_DATA_OFFSET PARAMETER_VALUE_OFFSET
 153
 154 #define MASTER_SLAVE_LENGTH 4
 155 #define MASTER_SLAVE_OFFSET PARAMETER_VALUE_OFFSET
 156
 157 #define REASON_LENGTH 4
 158 #define REASON_OFFSET PARAMETER_VALUE_OFFSET
 159
 160 #define HEART_BEAT_DATA_OFFSET PARAMETER_VALUE_OFFSET
 161
 162 #define ERROR_CODE_LENGTH 4
 163 #define ERROR_CODE_OFFSET PARAMETER_VALUE_OFFSET
 164
 165 #define INFO_STRING_OFFSET PARAMETER_VALUE_OFFSET
 166
 167 #define BSN_OFFSET PARAMETER_VALUE_OFFSET
 168 #define FSN_OFFSET PARAMETER_VALUE_OFFSET+1
 169
 170 #define M2TP_USER_MTP2          1
 171 #define M2TP_USER_Q921          2
 172 #define M2TP_USER_FRAME_RELAY   3
 173
 174 static const value_string m2tp_user_identifier_values[] = {
 175     { M2TP_USER_MTP2,        "MTP2" },
 176     { M2TP_USER_Q921,        "Q.921" },
 177     { M2TP_USER_FRAME_RELAY, "Frame Relay" },
 178     { 0, NULL }};
 179
 180 #define M2TP_MODE_MASTER 1
 181 #define M2TP_MODE_SLAVE  2
 182
 183 static const value_string m2tp_mode_values[] = {
 184     { M2TP_MODE_MASTER,      "Master" },
 185     { M2TP_MODE_SLAVE,       "Slave" },
 186     { 0, NULL}};
 187
 188 #define M2TP_ERROR_CODE_INVALID_VERSION                         1
 189 #define M2TP_ERROR_CODE_INVALID_INTERFACE_IDENTIFIER            2
 190 #define M2TP_ERROR_CODE_INVALID_ADAPTATION_LAYER_IDENTIFIER     3
 191 #define M2TP_ERROR_CODE_INVALID_MESSAGE_TYPE                    4
 192 #define M2TP_ERROR_CODE_INVALID_TRAFFIC_HANDLING_MODE           5
 193 #define M2TP_ERROR_CODE_UNEXPECTED_MESSAGE                      6
 194 #define M2TP_ERROR_CODE_PROTOCOL_ERROR                          7
 195 #define M2TP_ERROR_CODE_INVALID_STREAM_IDENTIFIER               8
 196 #define M2TP_ERROR_CODE_INCOMPATIBLE_MASTER_SLAVE_CONFIGURATION 9
 197
 198 static const value_string m2tp_error_code_values[] = {
 199       { M2TP_ERROR_CODE_INVALID_VERSION,                        "Invalid Version" },
 200       { M2TP_ERROR_CODE_INVALID_INTERFACE_IDENTIFIER,           "Invalid Interface Identifier" },
 201       { M2TP_ERROR_CODE_INVALID_ADAPTATION_LAYER_IDENTIFIER,    "Invalid Adaptation Layer Identifier" },
 202       { M2TP_ERROR_CODE_INVALID_MESSAGE_TYPE,                   "Invalid Message Type" },
 203       { M2TP_ERROR_CODE_INVALID_TRAFFIC_HANDLING_MODE,          "Invalid Traffic Handling Mode" },
 204       { M2TP_ERROR_CODE_UNEXPECTED_MESSAGE,                     "Unexpected Message" },
 205       { M2TP_ERROR_CODE_PROTOCOL_ERROR,                         "Protocol Error" },
 206       { M2TP_ERROR_CODE_INVALID_STREAM_IDENTIFIER,              "Invalid Stream Identified" },
 207       { M2TP_ERROR_CODE_INCOMPATIBLE_MASTER_SLAVE_CONFIGURATION,"Incompatible Master Slave Configuration" },
 208       { 0,                                                      NULL } };
 209
 210 #define MANAGEMENT_ORDER_REASON_CODE       1
 211 #define MTP_RELEASE_REASON_CODE            2
 212
 213 static const value_string m2tp_reason_code_values[] = {
 214       { MANAGEMENT_ORDER_REASON_CODE,                      "Management Order" },
 215       { MTP_RELEASE_REASON_CODE,                           "MTP Release" },
 216       { 0,                                                 NULL } };
 217
 218
 219 /* Initialize the protocol and registered fields */
 220 static int proto_m2tp = -1;
 221 static int hf_m2tp_version = -1;
 222 static int hf_m2tp_reserved = -1;
 223 static int hf_m2tp_message_class = -1;
 224 static int hf_m2tp_message_type = -1;
 225 static int hf_m2tp_message_length = -1;
 226 static int hf_m2tp_parameter_tag = -1;
 227 static int hf_m2tp_parameter_length = -1;
 228 static int hf_m2tp_parameter_value = -1;
 229 static int hf_m2tp_parameter_padding = -1;
 230 static int hf_m2tp_interface_identifier = -1;
 231 static int hf_m2tp_user = -1;
 232 static int hf_m2tp_master_slave = -1;
 233 static int hf_m2tp_info_string = -1;
 234 static int hf_m2tp_heartbeat_data = -1;
 235 static int hf_m2tp_diagnostic_info = -1;
 236 static int hf_m2tp_error_code = -1;
 237 static int hf_m2tp_reason = -1;
 238
 239 /* Initialize the subtree pointers */
 240 static gint ett_m2tp = -1;
 241 static gint ett_m2tp_parameter = -1;
 242
 243 static dissector_handle_t mtp2_handle;
 244
 245 static guint
 246 nr_of_padding_bytes (guint length)
 247 {
 248   guint remainder;
 249
 250   remainder = length % 4;
 251
 252   if (remainder == 0)
 253     return 0;
 254   else
 255     return 4 - remainder;
 256 }
 257
 258 /* Common Header */
 259 static void
 260 dissect_m2tp_common_header(tvbuff_t *common_header_tvb, packet_info *pinfo, proto_tree *m2tp_tree)
 261 {
 262   guint8  version, reserved, message_class, message_type;
 263   guint32 message_length;
 264
 265   /* Extract the common header */
 266   version        = tvb_get_guint8(common_header_tvb, VERSION_OFFSET);
 267   reserved       = tvb_get_guint8(common_header_tvb, RESERVED_OFFSET);
 268   message_class  = tvb_get_guint8(common_header_tvb, MESSAGE_CLASS_OFFSET);
 269   message_type   = tvb_get_guint8(common_header_tvb, MESSAGE_TYPE_OFFSET);
 270   message_length = tvb_get_ntohl (common_header_tvb, MESSAGE_LENGTH_OFFSET);
 271
 272   col_add_fstr(pinfo->cinfo, COL_INFO, "%s ", val_to_str_const(message_class * 256 + message_type, m2tp_message_class_type_acro_values, "reserved"));
 273
 274   if (m2tp_tree) {
 275     /* add the components of the common header to the protocol tree */
 276     proto_tree_add_uint(m2tp_tree, hf_m2tp_version, common_header_tvb, VERSION_OFFSET, VERSION_LENGTH, version);
 277     proto_tree_add_uint(m2tp_tree, hf_m2tp_reserved, common_header_tvb, RESERVED_OFFSET, RESERVED_LENGTH, reserved);
 278     proto_tree_add_uint(m2tp_tree, hf_m2tp_message_class, common_header_tvb, MESSAGE_CLASS_OFFSET, MESSAGE_CLASS_LENGTH, message_class);
 279     proto_tree_add_uint_format_value(m2tp_tree, hf_m2tp_message_type,
 280                                common_header_tvb, MESSAGE_TYPE_OFFSET, MESSAGE_TYPE_LENGTH,
 281                                message_type, "%u (%s)",
 282                                message_type, val_to_str_const(message_class * 256 + message_type, m2tp_message_class_type_values, "reserved"));
 283     proto_tree_add_uint(m2tp_tree, hf_m2tp_message_length, common_header_tvb, MESSAGE_LENGTH_OFFSET, MESSAGE_LENGTH_LENGTH, message_length);
 284   };
 285 }
 286
 287 /* Interface Identifier */
 288 static void
 289 dissect_m2tp_interface_identifier_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 290 {
 291   guint32 parameter_value;
 292
 293   if (parameter_tree) {
 294     parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
 295     proto_tree_add_uint(parameter_tree, hf_m2tp_interface_identifier, parameter_tvb, INTERFACE_IDENTIFIER_OFFSET, INTERFACE_IDENTIFIER_LENGTH, parameter_value);
 296     proto_item_set_text(parameter_item, "Interface Identifier (%u)", parameter_value);
 297   }
 298 }
 299
 300 /* Master Slave Indicator */
 301 static void
 302 dissect_m2tp_master_slave_parameter (tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 303 {
 304   guint32 parameter_value;
 305
 306   if (parameter_tree) {
 307     parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
 308     proto_tree_add_uint(parameter_tree, hf_m2tp_master_slave, parameter_tvb, MASTER_SLAVE_OFFSET, MASTER_SLAVE_LENGTH, parameter_value);
 309     proto_item_set_text(parameter_item, "Master Slave Indicator (%s)", val_to_str_const(parameter_value, m2tp_mode_values, "unknown"));
 310   }
 311 }
 312
 313 /* M2tp User Identifier */
 314 static void
 315 dissect_m2tp_user_identifier_parameter (tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 316 {
 317   guint32 parameter_value;
 318
 319   if (parameter_tree) {
 320     parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
 321     proto_tree_add_uint(parameter_tree, hf_m2tp_user, parameter_tvb, M2TP_USER_OFFSET, M2TP_USER_LENGTH, parameter_value);
 322     proto_item_set_text(parameter_item, "M2TP User Identifier (%u)", parameter_value);
 323   }
 324 }
 325
 326 /* Info String */
 327 static void
 328 dissect_m2tp_info_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 329 {
 330   guint16 length, info_string_length;
 331   const char *info_string;
 332
 333   if (parameter_tree) {
 334     length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 335     info_string_length = length - PARAMETER_HEADER_LENGTH;
 336     info_string = tvb_get_string(wmem_packet_scope(), parameter_tvb, INFO_STRING_OFFSET, info_string_length);
 337     proto_tree_add_string(parameter_tree, hf_m2tp_info_string, parameter_tvb, INFO_STRING_OFFSET, info_string_length, info_string);
 338     proto_item_set_text(parameter_item, "Info String (%.*s)", info_string_length, info_string);
 339   }
 340 }
 341
 342 /* Diagnostic Information */
 343 static void
 344 dissect_m2tp_diagnostic_information_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 345 {
 346   guint16 length, diagnostic_info_length;
 347
 348   if (parameter_tree) {
 349     length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 350     diagnostic_info_length = length - PARAMETER_HEADER_LENGTH;
 351     proto_tree_add_item(parameter_tree, hf_m2tp_diagnostic_info, parameter_tvb, PARAMETER_VALUE_OFFSET, diagnostic_info_length, ENC_NA);
 352     proto_item_set_text(parameter_item, "Diagnostic information (%u byte%s)", diagnostic_info_length, plurality(diagnostic_info_length, "", "s"));
 353   }
 354 }
 355
 356 /* Heartbeat Data */
 357 static void
 358 dissect_m2tp_heartbeat_data_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 359 {
 360   guint16 length, heartbeat_data_length;
 361
 362   if (parameter_tree) {
 363     length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 364     heartbeat_data_length = length - PARAMETER_HEADER_LENGTH;
 365     proto_tree_add_item(parameter_tree, hf_m2tp_heartbeat_data, parameter_tvb, PARAMETER_VALUE_OFFSET, heartbeat_data_length, ENC_NA);
 366     proto_item_set_text(parameter_item, "Heartbeat data (%u byte%s)", heartbeat_data_length, plurality(heartbeat_data_length, "", "s"));
 367   }
 368 }
 369
 370 /* Reason Parameter */
 371 static void
 372 dissect_m2tp_reason_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 373 {
 374   guint32 reason;
 375
 376   if (parameter_tree) {
 377     reason = tvb_get_ntohl(parameter_tvb, REASON_OFFSET);
 378     proto_tree_add_uint(parameter_tree, hf_m2tp_reason, parameter_tvb, REASON_OFFSET, REASON_LENGTH, reason);
 379     proto_item_set_text(parameter_item, "Reason parameter (%s)", val_to_str_const(reason, m2tp_reason_code_values, "unknown"));
 380   }
 381 }
 382
 383 /* Error Code */
 384 static void
 385 dissect_m2tp_error_code_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 386 {
 387   guint32 error_code;
 388
 389   if (parameter_tree) {
 390     error_code = tvb_get_ntohl(parameter_tvb, ERROR_CODE_OFFSET);
 391     proto_tree_add_uint(parameter_tree, hf_m2tp_error_code, parameter_tvb, ERROR_CODE_OFFSET, ERROR_CODE_LENGTH, error_code);
 392     proto_item_set_text(parameter_item, "Error code parameter (%s)", val_to_str_const(error_code, m2tp_error_code_values, "unknown"));
 393   }
 394 }
 395
 396 /* Protocol Data */
 397 static void
 398 dissect_m2tp_protocol_data_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item, packet_info *pinfo, proto_item *m2tp_item, proto_tree *tree)
 399 {
 400   guint16 length, protocol_data_length, padding_length;
 401   tvbuff_t *mtp2_tvb;
 402
 403   length               = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 404   padding_length       = nr_of_padding_bytes(length);
 405   protocol_data_length = length - PARAMETER_HEADER_LENGTH;
 406
 407   mtp2_tvb = tvb_new_subset(parameter_tvb, PARAMETER_VALUE_OFFSET, protocol_data_length, protocol_data_length);
 408   call_dissector(mtp2_handle, mtp2_tvb, pinfo, tree);
 409
 410   if (parameter_tree) {
 411     proto_item_set_text(parameter_item, "Protocol data (SS7 message)");
 412     proto_item_set_len(parameter_item, proto_item_get_len(parameter_item) - protocol_data_length - padding_length);
 413     proto_item_set_len(m2tp_item,      proto_item_get_len(m2tp_item)      - protocol_data_length - padding_length);
 414
 415   }
 416 }
 417
 418 /* Unknown Parameter */
 419 static void
 420 dissect_m2tp_unknown_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
 421 {
 422   guint16 tag, length, parameter_value_length;
 423
 424   if (parameter_tree) {
 425     tag    = tvb_get_ntohs(parameter_tvb, PARAMETER_TAG_OFFSET);
 426     length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 427
 428     parameter_value_length = length - PARAMETER_HEADER_LENGTH;
 429     proto_tree_add_item(parameter_tree, hf_m2tp_parameter_value, parameter_tvb, PARAMETER_VALUE_OFFSET, parameter_value_length, ENC_NA);
 430
 431     proto_item_set_text(parameter_item, "Parameter with tag %u and %u byte%s value", tag, parameter_value_length, plurality(parameter_value_length, "", "s"));
 432   }
 433 }
 434
 435 /* M2TP Parameter */
 436 static void
 437 dissect_m2tp_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo, proto_tree *m2tp_tree, proto_item *m2tp_item, proto_tree *tree)
 438 {
 439   guint16 tag, length, padding_length, total_length;
 440   proto_item *parameter_item = NULL;
 441   proto_tree *parameter_tree = NULL;
 442
 443   /* extract tag and length from the parameter */
 444   tag            = tvb_get_ntohs(parameter_tvb, PARAMETER_TAG_OFFSET);
 445   length         = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
 446
 447   /* calculate padding and total length */
 448   padding_length = nr_of_padding_bytes(length);
 449   total_length   = length + padding_length;
 450
 451   if (tree) {
 452     /* create proto_tree stuff */
 453     parameter_item   = proto_tree_add_text(m2tp_tree, parameter_tvb, PARAMETER_HEADER_OFFSET, total_length, "Incomplete parameter");
 454     parameter_tree   = proto_item_add_subtree(parameter_item, ett_m2tp_parameter);
 455
 456     /* add tag and length to the m2tp tree */
 457     proto_tree_add_uint(parameter_tree, hf_m2tp_parameter_tag, parameter_tvb, PARAMETER_TAG_OFFSET, PARAMETER_TAG_LENGTH, tag);
 458     proto_tree_add_uint(parameter_tree, hf_m2tp_parameter_length, parameter_tvb, PARAMETER_LENGTH_OFFSET, PARAMETER_LENGTH_LENGTH, length);
 459   }
 460
 461   switch(tag) {
 462     case INTERFACE_IDENTIFIER_PARAMETER_TAG:
 463       dissect_m2tp_interface_identifier_parameter(parameter_tvb, parameter_tree, parameter_item);
 464       break;
 465     case MASTER_SLAVE_INDICATOR_PARAMETER_TAG:
 466       dissect_m2tp_master_slave_parameter(parameter_tvb, parameter_tree, parameter_item);
 467       break;
 468     case M2TP_USER_IDENTIFIER_PARAMETER_TAG:
 469       dissect_m2tp_user_identifier_parameter(parameter_tvb, parameter_tree, parameter_item);
 470       break;
 471     case INFO_PARAMETER_TAG:
 472       dissect_m2tp_info_parameter(parameter_tvb, parameter_tree, parameter_item);
 473       break;
 474     case DIAGNOSTIC_INFORMATION_PARAMETER_TAG:
 475       dissect_m2tp_diagnostic_information_parameter(parameter_tvb, parameter_tree, parameter_item);
 476       break;
 477     case HEARTBEAT_DATA_PARAMETER_TAG:
 478       dissect_m2tp_heartbeat_data_parameter(parameter_tvb, parameter_tree, parameter_item);
 479       break;
 480     case REASON_PARAMETER_TAG:
 481       dissect_m2tp_reason_parameter(parameter_tvb, parameter_tree, parameter_item);
 482       break;
 483     case ERROR_CODE_PARAMETER_TAG:
 484       dissect_m2tp_error_code_parameter(parameter_tvb, parameter_tree, parameter_item);
 485       break;
 486     case PROTOCOL_DATA_PARAMETER_TAG:
 487       dissect_m2tp_protocol_data_parameter(parameter_tvb, parameter_tree, parameter_item, pinfo, m2tp_item, tree);
 488       break;
 489     default:
 490       dissect_m2tp_unknown_parameter(parameter_tvb, parameter_tree, parameter_item);
 491       break;
 492   };
 493
 494   if ((parameter_tree) && (padding_length > 0))
 495     proto_tree_add_item(parameter_tree, hf_m2tp_parameter_padding, parameter_tvb, PARAMETER_HEADER_OFFSET + length, padding_length, ENC_NA);
 496 }
 497
 498 /* M2TP Message */
 499 static void
 500 dissect_m2tp_message(tvbuff_t *message_tvb, packet_info *pinfo, proto_item *m2tp_item, proto_tree *m2tp_tree, proto_tree *tree)
 501 {
 502   gint offset, length, padding_length, total_length;
 503   tvbuff_t *common_header_tvb, *parameter_tvb;
 504
 505   offset = 0;
 506
 507   /* extract and process the common header */
 508   common_header_tvb = tvb_new_subset(message_tvb, offset, COMMON_HEADER_LENGTH, COMMON_HEADER_LENGTH);
 509   dissect_m2tp_common_header(common_header_tvb, pinfo, m2tp_tree);
 510   offset += COMMON_HEADER_LENGTH;
 511
 512   /* extract zero or more parameters and process them individually */
 513   while(tvb_reported_length_remaining(message_tvb, offset) > 0) {
 514     length         = tvb_get_ntohs(message_tvb, offset + PARAMETER_LENGTH_OFFSET);
 515     padding_length = nr_of_padding_bytes(length);
 516     total_length   = length + padding_length;
 517     /* create a tvb for the parameter including the padding bytes */
 518     parameter_tvb    = tvb_new_subset(message_tvb, offset, total_length, total_length);
 519     dissect_m2tp_parameter(parameter_tvb, pinfo, m2tp_tree, m2tp_item, tree);
 520     /* get rid of the handled parameter */
 521     offset += total_length;
 522   }
 523 }
 524
 525 /* M2tp */
 526 static void
 527 dissect_m2tp(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
 528 {
 529   proto_item *m2tp_item;
 530   proto_tree *m2tp_tree;
 531
 532   /* make entry in the Protocol column on summary display */
 533   col_set_str(pinfo->cinfo, COL_PROTOCOL, "M2TP");
 534
 535   /* In the interest of speed, if "tree" is NULL, don't do any work not
 536      necessary to generate protocol tree items. */
 537   if (tree) {
 538     /* create the m2tp protocol tree */
 539     m2tp_item = proto_tree_add_item(tree, proto_m2tp, message_tvb, 0, -1, ENC_NA);
 540     m2tp_tree = proto_item_add_subtree(m2tp_item, ett_m2tp);
 541   } else {
 542     m2tp_item = NULL;
 543     m2tp_tree = NULL;
 544   };
 545   /* dissect the message */
 546   dissect_m2tp_message(message_tvb, pinfo, m2tp_item, m2tp_tree, tree);
 547 }
 548
 549 /* Register the protocol with Wireshark */
 550 void
 551 proto_register_m2tp(void)
 552 {
 553
 554   /* Setup list of header fields */
 555   static hf_register_info hf[] = {
 556     { &hf_m2tp_version,
 557       { "Version", "m2tp.version",
 558         FT_UINT8, BASE_DEC, VALS(m2tp_protocol_version_values), 0x0,
 559         NULL, HFILL}
 560     },
 561     { &hf_m2tp_reserved,
 562       { "Reserved", "m2tp.reserved",
 563         FT_UINT8, BASE_HEX, NULL, 0x0,
 564         NULL, HFILL}
 565     },
 566     { &hf_m2tp_message_class,
 567       { "Message class", "m2tp.message_class",
 568         FT_UINT8, BASE_DEC, VALS(m2tp_message_class_values), 0x0,
 569         NULL, HFILL}
 570     },
 571     { &hf_m2tp_message_type,
 572       { "Message Type", "m2tp.message_type",
 573         FT_UINT8, BASE_DEC, NULL, 0x0,
 574         NULL, HFILL}
 575     },
 576     { &hf_m2tp_message_length,
 577       { "Message length", "m2tp.message_length",
 578         FT_UINT32, BASE_DEC, NULL, 0x0,
 579         NULL, HFILL}
 580     },
 581     { &hf_m2tp_parameter_tag,
 582       { "Parameter Tag", "m2tp.parameter_tag",
 583         FT_UINT16, BASE_DEC, VALS(m2tp_parameter_tag_values), 0x0,
 584         NULL, HFILL}
 585     },
 586     { &hf_m2tp_parameter_length,
 587       { "Parameter length", "m2tp.parameter_length",
 588         FT_UINT16, BASE_DEC, NULL, 0x0,
 589         NULL, HFILL}
 590     },
 591     { &hf_m2tp_parameter_value,
 592       { "Parameter Value", "m2tp.parameter_value",
 593               FT_BYTES, BASE_NONE, NULL, 0x0,
 594               NULL, HFILL }
 595     },
 596     { &hf_m2tp_parameter_padding,
 597       { "Padding", "m2tp.parameter_padding",
 598               FT_BYTES, BASE_NONE, NULL, 0x0,
 599               NULL, HFILL }
 600     },
 601     { &hf_m2tp_interface_identifier,
 602       { "Interface Identifier", "m2tp.interface_identifier",
 603         FT_UINT32, BASE_DEC, NULL, 0x0,
 604         NULL, HFILL}
 605     },
 606     { &hf_m2tp_user,
 607       { "M2tp User Identifier", "m2tp.user_identifier",
 608         FT_UINT32, BASE_DEC, VALS(m2tp_user_identifier_values), 0x0,
 609         NULL, HFILL}
 610     },
 611     { &hf_m2tp_master_slave,
 612       { "Master Slave Indicator", "m2tp.master_slave",
 613         FT_UINT32, BASE_DEC, VALS(m2tp_mode_values), 0x0,
 614         NULL, HFILL}
 615     },
 616     { &hf_m2tp_info_string,
 617       { "Info string", "m2tp.info_string",
 618         FT_STRING, BASE_NONE, NULL, 0x0,
 619         NULL, HFILL}
 620     },
 621     { &hf_m2tp_diagnostic_info,
 622       { "Diagnostic information", "m2tp.diagnostic_info",
 623                FT_BYTES, BASE_NONE, NULL, 0x0,
 624                NULL, HFILL }
 625     },
 626     { &hf_m2tp_heartbeat_data,
 627       { "Heartbeat data", "m2tp.heartbeat_data",
 628                FT_BYTES, BASE_NONE, NULL, 0x0,
 629                NULL, HFILL }
 630     },
 631     { &hf_m2tp_error_code,
 632       { "Error code", "m2tp.error_code",
 633         FT_UINT32, BASE_DEC, VALS(m2tp_error_code_values), 0x0,
 634         NULL, HFILL}
 635     },
 636     { &hf_m2tp_reason,
 637       { "Reason", "m2tp.reason",
 638         FT_UINT32, BASE_DEC, NULL, 0x0,
 639         NULL, HFILL}
 640     },
 641   };
 642
 643   /* Setup protocol subtree array */
 644   static gint *ett[] = {
 645     &ett_m2tp,
 646     &ett_m2tp_parameter,
 647   };
 648
 649   /* Register the protocol name and description */
 650   proto_m2tp = proto_register_protocol("MTP 2 Transparent Proxy", "M2TP",  "m2tp");
 651
 652   /* Required function calls to register the header fields and subtrees used */
 653   proto_register_field_array(proto_m2tp, hf, array_length(hf));
 654   proto_register_subtree_array(ett, array_length(ett));
 655 }
 656
 657 void
 658 proto_reg_handoff_m2tp(void)
 659 {
 660   dissector_handle_t m2tp_handle;
 661   mtp2_handle   = find_dissector("mtp2");
 662   m2tp_handle   = create_dissector_handle(dissect_m2tp, proto_m2tp);
 663   dissector_add_uint("sctp.ppi",  M2TP_PAYLOAD_PROTOCOL_ID, m2tp_handle);
 664   dissector_add_uint("sctp.port", SCTP_PORT_M2TP, m2tp_handle);
 665 }