M2TP support, from Heinz Prantner.

svn path=/trunk/; revision=4409

1 files changed, 683 insertions, 0 deletions

diff --git a/packet-m2tp.c b/packet-m2tp.c
new file mode 100644
index 0000000000..38fc4ec199
--- /dev/null
+++ b/packet-m2tp.c
@@ -0,0 +1,683 @@
+/* packet-m2tp.c
+ * Routines for M2TP User Adaptation Layer dissection
+ * M2TP - MTP2 Transparent Proxy - is a Radisys proprietary
+ * protocol based on the IETF SIGTRAN standard
+ *
+ * Copyright 2001, Heinz Prantner <heinz.prantner[AT]radisys.com>
+ *
+ * $Id: packet-m2tp.c,v 1.1 2001/12/16 22:30:09 guy Exp $
+ *
+ * Ethereal - Network traffic analyzer
+ * By Gerald Combs <gerald@ethereal.com>
+ * Copyright 1998 Gerald Combs
+ *
+ * Copied from packet-m3ua.c
+ * Thanks to Michael Tuexen for his valuable improvements
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <glib.h>
+
+#include "packet.h"
+
+#define SCTP_PORT_M2TP        9908  /* unassigned port number (not assigned by IANA) */
+#define M2TP_PAYLOAD_PROTO_ID 99    /* s-link */
+
+#define VERSION_LENGTH         1
+#define RESERVED_LENGTH        1
+#define MESSAGE_CLASS_LENGTH   1
+#define MESSAGE_TYPE_LENGTH    1
+#define MESSAGE_LENGTH_LENGTH  4
+#define COMMON_HEADER_LENGTH   (VERSION_LENGTH + RESERVED_LENGTH + MESSAGE_CLASS_LENGTH + \
+                                MESSAGE_TYPE_LENGTH + MESSAGE_LENGTH_LENGTH)
+
+#define VERSION_OFFSET         0
+#define RESERVED_OFFSET        (VERSION_OFFSET + VERSION_LENGTH)
+#define MESSAGE_CLASS_OFFSET   (RESERVED_OFFSET + RESERVED_LENGTH)
+#define MESSAGE_TYPE_OFFSET    (MESSAGE_CLASS_OFFSET + MESSAGE_CLASS_LENGTH)
+#define MESSAGE_LENGTH_OFFSET  (MESSAGE_TYPE_OFFSET + MESSAGE_TYPE_LENGTH)
+
+#define PARAMETER_TAG_LENGTH    2
+#define PARAMETER_LENGTH_LENGTH 2
+#define PARAMETER_HEADER_LENGTH (PARAMETER_TAG_LENGTH + PARAMETER_LENGTH_LENGTH)
+
+#define PARAMETER_TAG_OFFSET      0
+#define PARAMETER_LENGTH_OFFSET   (PARAMETER_TAG_OFFSET + PARAMETER_TAG_LENGTH)
+#define PARAMETER_VALUE_OFFSET    (PARAMETER_LENGTH_OFFSET + PARAMETER_LENGTH_LENGTH)
+#define PARAMETER_HEADER_OFFSET   PARAMETER_TAG_OFFSET
+
+#define INTERFACE_IDENTIFIER_PARAMETER_TAG     1
+#define MASTER_SLAVE_INDICATOR_PARAMETER_TAG   2
+#define M2TP_USER_IDENTIFIER_PARAMETER_TAG     3
+#define INFO_PARAMETER_TAG                     4
+#define DIAGNOSTIC_INFORMATION_PARAMETER_TAG   7
+#define HEARTBEAT_DATA_PARAMETER_TAG           9
+#define REASON_PARAMETER_TAG                  10
+#define ERROR_CODE_PARAMETER_TAG              12
+#define PROTOCOL_DATA_PARAMETER_TAG           13
+
+
+static const value_string m2tp_parameter_tag_values[] = {
+  { INTERFACE_IDENTIFIER_PARAMETER_TAG,         "Interface Identifier" },
+  { MASTER_SLAVE_INDICATOR_PARAMETER_TAG,       "Master Slave Indicator" },
+  { M2TP_USER_IDENTIFIER_PARAMETER_TAG,         "M2tp User Identifier" },
+  { INFO_PARAMETER_TAG,                         "Info" },
+  { DIAGNOSTIC_INFORMATION_PARAMETER_TAG,       "Diagnostic Information" },
+  { HEARTBEAT_DATA_PARAMETER_TAG,               "Heartbeat Data" },
+  { REASON_PARAMETER_TAG,                       "Reason" },
+  { ERROR_CODE_PARAMETER_TAG,                   "Error Code" },
+  { PROTOCOL_DATA_PARAMETER_TAG,                "Protocol Data" },
+  { 0,                           NULL } };
+
+#define PROTOCOL_VERSION_RELEASE_1             1
+
+static const value_string m2tp_protocol_version_values[] = {
+  { PROTOCOL_VERSION_RELEASE_1,  "Release 1" },
+  { 0,                           NULL } };
+
+#define MESSAGE_CLASS_MGMT_MESSAGE        0
+#define MESSAGE_CLASS_SGSM_MESSAGE        3
+#define MESSAGE_CLASS_MAUP_MESSAGE        6
+#define MESSAGE_CLASS_DATA_MESSAGE        255
+
+static const value_string m2tp_message_class_values[] = {
+  { MESSAGE_CLASS_MGMT_MESSAGE,   "Management Messages" },
+  { MESSAGE_CLASS_SGSM_MESSAGE,   "SG State Maintenance Messages" },
+  { MESSAGE_CLASS_MAUP_MESSAGE,   "MTP2 User Adaptation Messages" },
+  { MESSAGE_CLASS_DATA_MESSAGE,   "User Data Messages" },
+  { 0,                            NULL } };
+
+/* management messages */
+#define MESSAGE_TYPE_ERR                  0
+
+/* sg state maintenance messages */
+#define MESSAGE_TYPE_UP                   1
+#define MESSAGE_TYPE_DOWN                 2
+#define MESSAGE_TYPE_BEAT                 3
+#define MESSAGE_TYPE_UP_ACK               4
+#define MESSAGE_TYPE_DOWN_ACK             5
+#define MESSAGE_TYPE_BEAT_ACK             6
+
+/* mtp2 user message */
+#define MESSAGE_TYPE_DATA                 1
+
+
+static const value_string m2tp_message_class_type_values[] = {
+  { MESSAGE_CLASS_MGMT_MESSAGE  * 256 + MESSAGE_TYPE_ERR,           "Error (ERR)" },
+  { MESSAGE_CLASS_DATA_MESSAGE  * 256 + MESSAGE_TYPE_DATA,          "Payload data (DATA)" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP,            "ASP up (UP)" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN,          "ASP down (DOWN)" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT,          "Heartbeat (BEAT)" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP_ACK,        "ASP up ack (UP ACK)" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN_ACK,      "ASP down ack (DOWN ACK)" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT_ACK,      "Heartbeat ack (BEAT ACK)" },
+  { 0,                           NULL } };
+
+static const value_string m2tp_message_class_type_acro_values[] = {
+  { MESSAGE_CLASS_MGMT_MESSAGE  * 256 + MESSAGE_TYPE_ERR,           "ERR" },
+  { MESSAGE_CLASS_DATA_MESSAGE  * 256 + MESSAGE_TYPE_DATA,          "DATA" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP,            "ASP_UP" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN,          "ASP_DOWN" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT,          "BEAT" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_UP_ACK,        "ASP_UP_ACK" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_DOWN_ACK,      "ASP_DOWN_ACK" },
+  { MESSAGE_CLASS_SGSM_MESSAGE  * 256 + MESSAGE_TYPE_BEAT_ACK,      "BEAT_ACK" },
+  { 0,                           NULL } };
+
+
+
+#define HEARTBEAT_PERIOD_OFFSET PARAMETER_VALUE_OFFSET
+
+#define INTERFACE_IDENTIFIER_LENGTH 4
+#define INTERFACE_IDENTIFIER_OFFSET PARAMETER_VALUE_OFFSET
+
+#define M2TP_USER_LENGTH 4
+#define M2TP_USER_OFFSET PARAMETER_VALUE_OFFSET
+
+#define PROTOCOL_DATA_OFFSET PARAMETER_VALUE_OFFSET
+  
+#define MASTER_SLAVE_LENGTH 4
+#define MASTER_SLAVE_OFFSET PARAMETER_VALUE_OFFSET
+
+#define REASON_LENGTH 4
+#define REASON_OFFSET PARAMETER_VALUE_OFFSET
+
+#define HEART_BEAT_DATA_OFFSET PARAMETER_VALUE_OFFSET
+
+#define ERROR_CODE_LENGTH 4
+#define ERROR_CODE_OFFSET PARAMETER_VALUE_OFFSET
+  
+#define INFO_STRING_OFFSET PARAMETER_VALUE_OFFSET
+
+#define BSN_OFFSET PARAMETER_VALUE_OFFSET
+#define FSN_OFFSET PARAMETER_VALUE_OFFSET+1
+
+#define M2TP_USER_MTP2          1
+#define M2TP_USER_Q921          2
+#define M2TP_USER_FRAME_RELAY   3
+
+static const value_string m2tp_user_identifier_values[] = {
+    { M2TP_USER_MTP2,        "MTP2" },
+    { M2TP_USER_Q921,        "Q.921" },
+    { M2TP_USER_FRAME_RELAY, "Frame Relay" },
+    { 0, NULL }};
+
+#define M2TP_MODE_MASTER 1
+#define M2TP_MODE_SLAVE  2
+
+static const value_string m2tp_mode_values[] = {
+    { M2TP_MODE_MASTER,      "Master" },
+    { M2TP_MODE_SLAVE,       "Slave" },
+    { 0, NULL}};
+    
+#define M2TP_ERROR_CODE_INVALID_VERSION                         1
+#define M2TP_ERROR_CODE_INVALID_INTERFACE_IDENTIFIER            2
+#define M2TP_ERROR_CODE_INVALID_ADAPTATION_LAYER_IDENTIFIER     3
+#define M2TP_ERROR_CODE_INVALID_MESSAGE_TYPE                    4
+#define M2TP_ERROR_CODE_INVALID_TRAFFIC_HANDLING_MODE           5
+#define M2TP_ERROR_CODE_UNEXPECTED_MESSAGE                      6
+#define M2TP_ERROR_CODE_PROTOCOL_ERROR                          7
+#define M2TP_ERROR_CODE_INVALID_STREAM_IDENTIFIER               8
+#define M2TP_ERROR_CODE_INCOMPATIBLE_MASTER_SLAVE_CONFIGURATION 9
+
+static const value_string m2tp_error_code_values[] = {
+      { M2TP_ERROR_CODE_INVALID_VERSION,                        "Invalid Version" },
+      { M2TP_ERROR_CODE_INVALID_INTERFACE_IDENTIFIER,           "Invalid Interface Identifier" },
+      { M2TP_ERROR_CODE_INVALID_ADAPTATION_LAYER_IDENTIFIER,    "Invalid Adaptation Layer Identifier" },
+      { M2TP_ERROR_CODE_INVALID_MESSAGE_TYPE,                   "Invalid Message Type" },
+      { M2TP_ERROR_CODE_INVALID_TRAFFIC_HANDLING_MODE,          "Invalid Traffic Handling Mode" },
+      { M2TP_ERROR_CODE_UNEXPECTED_MESSAGE,                     "Unexpected Message" },
+      { M2TP_ERROR_CODE_PROTOCOL_ERROR,                         "Protocol Error" },
+      { M2TP_ERROR_CODE_INVALID_STREAM_IDENTIFIER,              "Invalid Stream Identified" },
+      { M2TP_ERROR_CODE_INCOMPATIBLE_MASTER_SLAVE_CONFIGURATION,"Incompatible Master Slave Configuration" },
+      { 0,                                                      NULL } };
+
+#define MANAGEMENT_ORDER_REASON_CODE       1
+#define MTP_RELEASE_REASON_CODE            2
+
+static const value_string m2tp_reason_code_values[] = {
+      { MANAGEMENT_ORDER_REASON_CODE,                      "Management Order" },
+      { MTP_RELEASE_REASON_CODE,                           "MTP Release" },
+      { 0,                                                 NULL } };
+
+      
+/* Initialize the protocol and registered fields */
+static int proto_m2tp = -1;
+static int hf_m2tp_version = -1;
+static int hf_m2tp_reserved = -1;
+static int hf_m2tp_message_class = -1;
+static int hf_m2tp_message_type = -1;
+static int hf_m2tp_message_length = -1;
+static int hf_m2tp_parameter_tag = -1;
+static int hf_m2tp_parameter_length = -1;
+static int hf_m2tp_parameter_value = -1;
+static int hf_m2tp_parameter_padding = -1;
+static int hf_m2tp_interface_identifier = -1;
+static int hf_m2tp_user = -1;
+static int hf_m2tp_master_slave = -1;
+static int hf_m2tp_info_string = -1;
+static int hf_m2tp_heartbeat_data = -1;
+static int hf_m2tp_diagnostic_info = -1;
+static int hf_m2tp_error_code = -1;
+static int hf_m2tp_reason = -1;
+
+/* Initialize the subtree pointers */
+static gint ett_m2tp = -1;
+static gint ett_m2tp_parameter = -1;
+
+static dissector_handle_t mtp2_handle;
+static int mtp2_proto_id;
+
+static guint 
+nr_of_padding_bytes (guint length)
+{
+  guint remainder;
+
+  remainder = length % 4;
+
+  if (remainder == 0)
+    return 0;
+  else
+    return 4 - remainder;
+}
+
+/* Common Header */
+static void
+dissect_m2tp_common_header(tvbuff_t *common_header_tvb, packet_info *pinfo, proto_tree *m2tp_tree)
+{
+  guint8  version, reserved, message_class, message_type;
+  guint32 message_length;
+  
+  /* Extract the common header */
+  version        = tvb_get_guint8(common_header_tvb, VERSION_OFFSET);
+  reserved       = tvb_get_guint8(common_header_tvb, RESERVED_OFFSET);
+  message_class  = tvb_get_guint8(common_header_tvb, MESSAGE_CLASS_OFFSET);
+  message_type   = tvb_get_guint8(common_header_tvb, MESSAGE_TYPE_OFFSET);
+  message_length = tvb_get_ntohl (common_header_tvb, MESSAGE_LENGTH_OFFSET);
+
+  if ((check_col(pinfo->cinfo, COL_INFO)) && (message_class != MESSAGE_CLASS_DATA_MESSAGE)){
+    col_append_str(pinfo->cinfo, COL_INFO,
+        val_to_str(message_class * 256 + message_type, m2tp_message_class_type_acro_values, "reserved"));
+    col_append_str(pinfo->cinfo, COL_INFO, " ");
+  };
+
+  if (m2tp_tree) {
+    /* add the components of the common header to the protocol tree */
+    proto_tree_add_uint(m2tp_tree, hf_m2tp_version, common_header_tvb, VERSION_OFFSET, VERSION_LENGTH, version);
+    proto_tree_add_uint(m2tp_tree, hf_m2tp_reserved, common_header_tvb, RESERVED_OFFSET, RESERVED_LENGTH, reserved);
+    proto_tree_add_uint(m2tp_tree, hf_m2tp_message_class, common_header_tvb, MESSAGE_CLASS_OFFSET, MESSAGE_CLASS_LENGTH, message_class);
+    proto_tree_add_uint_format(m2tp_tree, hf_m2tp_message_type, 
+                               common_header_tvb, MESSAGE_TYPE_OFFSET, MESSAGE_TYPE_LENGTH,
+                               message_type, "Message type: %u (%s)",
+                               message_type, val_to_str(message_class * 256 + message_type, m2tp_message_class_type_values, "reserved"));
+    proto_tree_add_uint(m2tp_tree, hf_m2tp_message_length, common_header_tvb, MESSAGE_LENGTH_OFFSET, MESSAGE_LENGTH_LENGTH, message_length);
+  };
+}
+
+/* Interface Identifier */
+static void
+dissect_m2tp_interface_identifier_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint32 parameter_value;
+
+  if (parameter_tree) {
+    parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
+    proto_tree_add_uint(parameter_tree, hf_m2tp_interface_identifier, parameter_tvb, INTERFACE_IDENTIFIER_OFFSET, INTERFACE_IDENTIFIER_LENGTH, parameter_value);
+    proto_item_set_text(parameter_item, "Interface Identifier (%u)", parameter_value);
+  }
+}
+
+/* Master Slave Indicator */
+static void
+dissect_m2tp_master_slave_parameter (tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint32 parameter_value;
+
+  if (parameter_tree) {
+    parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
+    proto_tree_add_uint(parameter_tree, hf_m2tp_master_slave, parameter_tvb, MASTER_SLAVE_OFFSET, MASTER_SLAVE_LENGTH, parameter_value);
+    proto_item_set_text(parameter_item, "Master Slave Indicator (%s)", val_to_str(parameter_value, m2tp_mode_values, "unknown"));
+  }
+}
+
+/* M2tp User Identifier */
+static void
+dissect_m2tp_user_identifier_parameter (tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint32 parameter_value;
+
+  if (parameter_tree) {
+    parameter_value = tvb_get_ntohl(parameter_tvb, PARAMETER_VALUE_OFFSET);
+    proto_tree_add_uint(parameter_tree, hf_m2tp_user, parameter_tvb, M2TP_USER_OFFSET, M2TP_USER_LENGTH, parameter_value);
+    proto_item_set_text(parameter_item, "M2TP User Identifier (%u)", parameter_value);
+  }
+}
+
+/* Info String */
+static void
+dissect_m2tp_info_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint16 length, info_string_length;
+  char *info_string;
+
+  if (parameter_tree) {
+    length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
+    info_string_length = length - PARAMETER_HEADER_LENGTH;
+    info_string = (char *)tvb_get_ptr(parameter_tvb, INFO_STRING_OFFSET, info_string_length);
+    proto_tree_add_string(parameter_tree, hf_m2tp_info_string, parameter_tvb, INFO_STRING_OFFSET, info_string_length, info_string);
+    proto_item_set_text(parameter_item, "Info String (%.*s)", info_string_length, info_string);
+  }
+}
+
+/* Diagnostic Information */
+static void
+dissect_m2tp_diagnostic_information_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint16 length, diagnostic_info_length;
+  
+  if (parameter_tree) {
+    length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);  
+    diagnostic_info_length = length - PARAMETER_HEADER_LENGTH;
+    proto_tree_add_bytes(parameter_tree, hf_m2tp_diagnostic_info, parameter_tvb, PARAMETER_VALUE_OFFSET, diagnostic_info_length,
+                         tvb_get_ptr(parameter_tvb, PARAMETER_VALUE_OFFSET, diagnostic_info_length));
+    proto_item_set_text(parameter_item, "Diagnostic information (%u byte%s)", diagnostic_info_length, plurality(diagnostic_info_length, "", "s"));
+  }
+}
+
+/* Heartbeat Data */
+static void
+dissect_m2tp_heartbeat_data_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint16 length, heartbeat_data_length;
+  
+  if (parameter_tree) {
+    length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
+    heartbeat_data_length = length - PARAMETER_HEADER_LENGTH;
+    proto_tree_add_bytes(parameter_tree, hf_m2tp_heartbeat_data, parameter_tvb, PARAMETER_VALUE_OFFSET, heartbeat_data_length,
+                         tvb_get_ptr(parameter_tvb, PARAMETER_VALUE_OFFSET, heartbeat_data_length));
+    proto_item_set_text(parameter_item, "Heartbeat data (%u byte%s)", heartbeat_data_length, plurality(heartbeat_data_length, "", "s"));
+  }
+}
+
+/* Reason Parameter */
+static void
+dissect_m2tp_reason_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint32 reason;
+
+  if (parameter_tree) {
+    reason = tvb_get_ntohl(parameter_tvb, REASON_OFFSET);
+    proto_tree_add_uint(parameter_tree, hf_m2tp_reason, parameter_tvb, REASON_OFFSET, REASON_LENGTH, reason);
+    proto_item_set_text(parameter_item, "Reason parameter (%s)", val_to_str(reason, m2tp_reason_code_values, "unknown"));
+  }
+}
+
+/* Error Code */
+static void
+dissect_m2tp_error_code_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint32 error_code;
+
+  if (parameter_tree) {
+    error_code = tvb_get_ntohl(parameter_tvb, ERROR_CODE_OFFSET);
+    proto_tree_add_uint(parameter_tree, hf_m2tp_error_code, parameter_tvb, ERROR_CODE_OFFSET, ERROR_CODE_LENGTH, error_code);
+    proto_item_set_text(parameter_item, "Error code parameter (%s)", val_to_str(error_code, m2tp_error_code_values, "unknown"));
+  }
+}
+
+/* Protocol Data */
+static void
+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)
+{
+  guint16 length, protocol_data_length, padding_length;
+  tvbuff_t *mtp2_tvb;
+
+  length               = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
+  padding_length       = nr_of_padding_bytes(length);
+  protocol_data_length = length - PARAMETER_HEADER_LENGTH;
+
+  mtp2_tvb = tvb_new_subset(parameter_tvb, PARAMETER_VALUE_OFFSET, protocol_data_length, protocol_data_length);
+  call_dissector(mtp2_handle, mtp2_tvb, pinfo, tree);
+
+  if ((check_col(pinfo->cinfo, COL_INFO)) && (!proto_is_protocol_enabled(mtp2_proto_id)))
+    col_append_str(pinfo->cinfo, COL_INFO, "DATA");
+
+  if (parameter_tree) {
+    proto_item_set_text(parameter_item, "Protocol data (SS7 message)");
+    proto_item_set_len(parameter_item, proto_item_get_len(parameter_item) - protocol_data_length - padding_length);
+    proto_item_set_len(m2tp_item,      proto_item_get_len(m2tp_item)      - protocol_data_length - padding_length);
+
+  }
+}
+
+/* Unknown Parameter */
+static void
+dissect_m2tp_unknown_parameter(tvbuff_t *parameter_tvb, proto_tree *parameter_tree, proto_item *parameter_item)
+{
+  guint16 tag, length, parameter_value_length;
+  
+  if (parameter_tree) {
+    tag    = tvb_get_ntohs(parameter_tvb, PARAMETER_TAG_OFFSET);
+    length = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
+    
+    parameter_value_length = length - PARAMETER_HEADER_LENGTH;
+    proto_tree_add_bytes(parameter_tree, hf_m2tp_parameter_value, 
+                        parameter_tvb, PARAMETER_VALUE_OFFSET, parameter_value_length,
+                        tvb_get_ptr(parameter_tvb, PARAMETER_VALUE_OFFSET, parameter_value_length));
+  
+    proto_item_set_text(parameter_item, "Parameter with tag %u and %u byte%s value", tag, parameter_value_length, plurality(parameter_value_length, "", "s"));
+  }
+}
+
+/* M2TP Parameter */
+static void
+dissect_m2tp_parameter(tvbuff_t *parameter_tvb, packet_info *pinfo, proto_tree *m2tp_tree, proto_item *m2tp_item, proto_tree *tree)
+{
+  guint16 tag, length, padding_length, total_length;
+  proto_item *parameter_item = NULL;
+  proto_tree *parameter_tree = NULL;
+
+  /* extract tag and length from the parameter */
+  tag            = tvb_get_ntohs(parameter_tvb, PARAMETER_TAG_OFFSET);
+  length         = tvb_get_ntohs(parameter_tvb, PARAMETER_LENGTH_OFFSET);
+
+  /* calculate padding and total length */
+  padding_length = nr_of_padding_bytes(length);
+  total_length   = length + padding_length;
+
+  if (tree) {
+    /* create proto_tree stuff */
+    parameter_item   = proto_tree_add_text(m2tp_tree, parameter_tvb, PARAMETER_HEADER_OFFSET, total_length, "Incomplete parameter");
+    parameter_tree   = proto_item_add_subtree(parameter_item, ett_m2tp_parameter);
+  
+    /* add tag and length to the m2tp tree */
+    proto_tree_add_uint(parameter_tree, hf_m2tp_parameter_tag, parameter_tvb, PARAMETER_TAG_OFFSET, PARAMETER_TAG_LENGTH, tag);
+    proto_tree_add_uint(parameter_tree, hf_m2tp_parameter_length, parameter_tvb, PARAMETER_LENGTH_OFFSET, PARAMETER_LENGTH_LENGTH, length);
+  }
+    
+  switch(tag) {
+    case INTERFACE_IDENTIFIER_PARAMETER_TAG:
+      dissect_m2tp_interface_identifier_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+    case MASTER_SLAVE_INDICATOR_PARAMETER_TAG:
+      dissect_m2tp_master_slave_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+    case M2TP_USER_IDENTIFIER_PARAMETER_TAG:
+      dissect_m2tp_user_identifier_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+    case INFO_PARAMETER_TAG:
+      dissect_m2tp_info_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+    case DIAGNOSTIC_INFORMATION_PARAMETER_TAG:
+      dissect_m2tp_diagnostic_information_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+    case HEARTBEAT_DATA_PARAMETER_TAG:
+      dissect_m2tp_heartbeat_data_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+    case REASON_PARAMETER_TAG:
+      dissect_m2tp_reason_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+    case ERROR_CODE_PARAMETER_TAG:
+      dissect_m2tp_error_code_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+    case PROTOCOL_DATA_PARAMETER_TAG:
+      dissect_m2tp_protocol_data_parameter(parameter_tvb, parameter_tree, parameter_item, pinfo, m2tp_item, tree);
+      break;
+    default:
+      dissect_m2tp_unknown_parameter(parameter_tvb, parameter_tree, parameter_item);
+      break;
+  };
+
+  if ((parameter_tree) && (padding_length > 0))
+    proto_tree_add_bytes(parameter_tree, hf_m2tp_parameter_padding, 
+                         parameter_tvb, PARAMETER_HEADER_OFFSET + length, padding_length,
+                         tvb_get_ptr(parameter_tvb, PARAMETER_HEADER_OFFSET + length, padding_length));
+}
+
+/* M2TP Message */
+static void
+dissect_m2tp_message(tvbuff_t *message_tvb, packet_info *pinfo, proto_item *m2tp_item, proto_tree *m2tp_tree, proto_tree *tree)
+{
+  gint offset, length, padding_length, total_length;
+  tvbuff_t *common_header_tvb, *parameter_tvb;
+
+  offset = 0;
+
+  /* extract and process the common header */
+  common_header_tvb = tvb_new_subset(message_tvb, offset, COMMON_HEADER_LENGTH, COMMON_HEADER_LENGTH);
+  dissect_m2tp_common_header(common_header_tvb, pinfo, m2tp_tree);
+  offset += COMMON_HEADER_LENGTH;
+  
+  /* extract zero or more parameters and process them individually */
+  while(tvb_length_remaining(message_tvb, offset)) {
+    length         = tvb_get_ntohs(message_tvb, offset + PARAMETER_LENGTH_OFFSET);
+    padding_length = nr_of_padding_bytes(length);
+    total_length   = length + padding_length;
+    /* create a tvb for the parameter including the padding bytes */
+    parameter_tvb    = tvb_new_subset(message_tvb, offset, total_length, total_length);
+    dissect_m2tp_parameter(parameter_tvb, pinfo, m2tp_tree, m2tp_item, tree); 
+    /* get rid of the handled parameter */
+    offset += total_length;
+  }
+}
+
+/* M2tp */
+static void
+dissect_m2tp(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
+{
+  proto_item *m2tp_item;
+  proto_tree *m2tp_tree;
+
+  /* make entry in the Protocol column on summary display */
+  if (check_col(pinfo->cinfo, COL_PROTOCOL)) 
+    col_set_str(pinfo->cinfo, COL_PROTOCOL, "M2TP");
+  
+  /* In the interest of speed, if "tree" is NULL, don't do any work not
+     necessary to generate protocol tree items. */
+  if (tree) {
+    /* create the m2tp protocol tree */
+    m2tp_item = proto_tree_add_item(tree, proto_m2tp, message_tvb, 0, tvb_length(message_tvb), FALSE);
+    m2tp_tree = proto_item_add_subtree(m2tp_item, ett_m2tp);
+  } else {
+    m2tp_item = NULL;
+    m2tp_tree = NULL;
+  };
+  /* dissect the message */
+  dissect_m2tp_message(message_tvb, pinfo, m2tp_item, m2tp_tree, tree);
+}
+
+/* Register the protocol with Ethereal */
+void
+proto_register_m2tp(void)
+{                 
+
+  /* Setup list of header fields */
+  static hf_register_info hf[] = {
+    { &hf_m2tp_version,
+      { "Version", "m2tp.version",
+        FT_UINT8, BASE_DEC, VALS(m2tp_protocol_version_values), 0x0,          
+        "", HFILL}
+    },
+    { &hf_m2tp_reserved,
+      { "Reserved", "m2tp.reserved",
+        FT_UINT8, BASE_HEX, NULL, 0x0,          
+        "", HFILL}
+    }, 
+    { &hf_m2tp_message_class,
+      { "Message class", "m2tp.message_class",
+        FT_UINT8, BASE_DEC, VALS(m2tp_message_class_values), 0x0,          
+        "", HFILL}
+    },
+    { &hf_m2tp_message_type,
+      { "Message Type", "m2tp.message_type",
+        FT_UINT8, BASE_DEC, NULL, 0x0,          
+        "", HFILL}
+    },
+    { &hf_m2tp_message_length,
+      { "Message length", "m2tp.message_length",
+        FT_UINT32, BASE_DEC, NULL, 0x0,          
+        "", HFILL}
+    }, 
+    { &hf_m2tp_parameter_tag,
+      { "Parameter Tag", "m2tp.parameter_tag",
+        FT_UINT16, BASE_DEC, VALS(m2tp_parameter_tag_values), 0x0,          
+        "", HFILL}
+    },
+    { &hf_m2tp_parameter_length,
+      { "Parameter length", "m2tp.parameter_length",
+        FT_UINT16, BASE_DEC, NULL, 0x0,          
+        "", HFILL}
+    }, 
+    { &hf_m2tp_parameter_value,
+      { "Parameter Value", "m2tp.parameter_value",
+	      FT_BYTES, BASE_NONE, NULL, 0x0,          
+	      "", HFILL }
+    },
+    { &hf_m2tp_parameter_padding,
+      { "Padding", "m2tp.parameter_padding",
+	      FT_BYTES, BASE_NONE, NULL, 0x0,          
+	      "", HFILL }
+    },   
+    { &hf_m2tp_interface_identifier,
+      { "Interface Identifier", "m2tp.interface_identifier",
+        FT_UINT32, BASE_DEC, NULL, 0x0,          
+        "", HFILL}
+    }, 
+    { &hf_m2tp_user,
+      { "M2tp User Identifier", "m2tp.user_identifier",
+        FT_UINT32, BASE_DEC, VALS(m2tp_user_identifier_values), 0x0,          
+        "", HFILL}
+    }, 
+    { &hf_m2tp_master_slave,
+      { "Master Slave Indicator", "m2tp.master_slave",
+        FT_UINT32, BASE_DEC, VALS(m2tp_mode_values), 0x0,          
+        "", HFILL}
+    }, 
+    { &hf_m2tp_info_string,
+      { "Info string", "m2tp.info_string",
+        FT_STRING, BASE_DEC, NULL, 0x0,          
+        "", HFILL}
+    }, 
+    { &hf_m2tp_diagnostic_info,
+      { "Diagnostic information", "m2tp.diagnostic_info",
+	       FT_BYTES, BASE_NONE, NULL, 0x0,          
+	       "", HFILL }
+    },
+    { &hf_m2tp_heartbeat_data,
+      { "Heartbeat data", "m2tp.heartbeat_data",
+	       FT_BYTES, BASE_NONE, NULL, 0x0,          
+	       "", HFILL }
+    },
+    { &hf_m2tp_error_code,
+      { "Error code", "m2tp.error_code",
+        FT_UINT32, BASE_DEC, VALS(m2tp_error_code_values), 0x0,          
+        "", HFILL}
+    }, 
+    { &hf_m2tp_reason,
+      { "Reason", "m2tp.reason",
+        FT_UINT32, BASE_DEC, NULL, 0x0,          
+        "", HFILL}
+    }, 
+  };
+  
+  /* Setup protocol subtree array */
+  static gint *ett[] = {
+    &ett_m2tp,
+    &ett_m2tp_parameter,
+  };
+  
+  /* Register the protocol name and description */
+  proto_m2tp = proto_register_protocol("MTP 2 Transparent Proxy", "M2TP",  "m2tp");
+
+  /* Required function calls to register the header fields and subtrees used */
+  proto_register_field_array(proto_m2tp, hf, array_length(hf));
+  proto_register_subtree_array(ett, array_length(ett));
+};
+
+void
+proto_reg_handoff_m2tp(void)
+{
+  dissector_handle_t m2tp_handle;
+  mtp2_handle   = find_dissector("mtp2");
+  mtp2_proto_id = proto_get_id_by_filter_name("mtp2");
+  m2tp_handle   = create_dissector_handle(dissect_m2tp, proto_m2tp);
+  dissector_add("sctp.ppi",  M2TP_PAYLOAD_PROTO_ID, m2tp_handle);
+  dissector_add("sctp.port", SCTP_PORT_M2TP, m2tp_handle);
+}