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packet-armagetronad.c

/* packet-armagetronad.c
 * Routines for the Armagetronad packet dissection
 * Copyright 2005, Guillaume Chazarain <guichaz@yahoo.fr>
 *
 * $Id: packet-armagetronad.c 29340 2009-08-09 06:26:46Z krj $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * 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 <epan/packet.h>
#include <epan/emem.h>

/* Initialize the protocol and registered fields */
static int proto_armagetronad = -1;
static int hf_armagetronad_descriptor_id = -1;
static int hf_armagetronad_message_id = -1;
static int hf_armagetronad_data_len = -1;
static int hf_armagetronad_data = -1;
static int hf_armagetronad_sender_id = -1;
static int hf_armagetronad_msg_subtree = -1;

/* Initialize the subtree pointers */
static gint ett_armagetronad = -1;
static gint ett_message = -1;

#define UDP_PORT_ARMAGETRONAD 4534
#define UDP_PORT_MASTER 4533

/*
 * The ACK packet is so common that we treat it
 * differently: it has no MessageID
 */
#define ACK 1

/*
 * armagetronad-0.2.8.2.1
 * The numbers and names were retrieved at runtime using the
 * 'nDescriptor* descriptors[MAXDESCRIPTORS]' array
 */
static const value_string descriptors[] = {
      {1, "ack"},
      {2, "req_info"},
      {3, "login_deny"},
      {4, "login_ignore"},
      {5, "login_accept"},
      {6, "login1"},
      {7, "logout"},
      {8, "sn_ConsoleOut"},
      {9, "client_cen"},
      {10, "version"},
      {11, "login2"},
      {20, "req_id"},
      {21, "id_req_handler"},
      {22, "net_destroy"},
      {23, "net_control"},
      {24, "net_sync"},
      {25, "ready to get objects"},
      {26, "net_clear"},
      {27, "sync_ack"},
      {28, "sync_msg"},
      {40, "password_request"},
      {41, "password_answer"},
      {50, "small_server"},
      {51, "big_server"},
      {52, "small_request"},
      {53, "big_request"},
      {54, "big_server_master"},
      {55, "big_request_master"},
      {60, "transfer config"},
      {200, "Chat"},
      {201, "ePlayerNetID"},
      {202, "player_removed_from_game"},
      {203, "Chat Client"},
      {210, "eTimer"},
      {220, "eTeam"},
      {230, "vote cast"},
      {231, "Kick vote"},
      {232, "Server controlled vote"},
      {233, "Server controlled vote expired"},
      {300, "gNetPlayerWall"},
      {310, "game"},
      {311, "client_gamestate"},
      {320, "cycle"},
      {321, "destination"},
      {330, "gAIPlayer"},
      {331, "gAITeam"},
      {340, "zone"},
      {0, NULL}
};

static gboolean
is_armagetronad_packet(tvbuff_t * tvb)
{
      gint offset = 0;

      /* For each message in the frame */
      while (tvb_length_remaining(tvb, offset) > 2) {
            gint data_len = tvb_get_ntohs(tvb, offset + 4) * 2;

#if 0
            /*
             * If the descriptor_id is not in the table it's possibly
             * because the protocol evoluated, losing synchronization
             * with the table, that's why we don't consider that as
             * a heuristic
             */
            if (!match_strval(tvb_get_ntohs(tvb, offset), descriptors))
                  /* DescriptorID not found in the table */
                  return FALSE;
#endif

            if (!tvb_bytes_exist(tvb, offset + 6, data_len))
                  /* Advertised length too long */
                  return FALSE;

            offset += 6 + data_len;
      }

      /* The packed should end with a 2 bytes ID */
      return tvb_length_remaining(tvb, offset) == 2;
}

static void
add_message_data(tvbuff_t * tvb, gint offset, gint data_len, proto_tree * tree)
{
      gchar *data = NULL;
      gchar tmp;
      int i;

      if (!tree)
            return;

      data = tvb_memcpy(tvb, ep_alloc(data_len + 1), offset, data_len);
      data[data_len] = '\0';

      for (i = 0; i < data_len; i += 2) {
            /*
             * There must be a better way to tell
             * Wireshark not to stop on null bytes
             * as the length is known
             */
            if (!data[i])
                  data[i] = ' ';

            if (!data[i+1])
                  data[i+1] = ' ';

            /* Armagetronad swaps unconditionally */
            tmp = data[i];
            data[i] = data[i+1];
            data[i+1] = tmp;
      }

      proto_tree_add_string(tree, hf_armagetronad_data, tvb, offset,
                        data_len, (gchar *) data);
}

static gint
add_message(tvbuff_t * tvb, gint offset, proto_tree * tree, GString * info)
{
      guint16 descriptor_id, message_id;
      gint data_len;
      proto_item *msg;
      proto_tree *msg_tree;
      const gchar *descriptor;

      descriptor_id = tvb_get_ntohs(tvb, offset);
      message_id = tvb_get_ntohs(tvb, offset + 2);
      data_len = tvb_get_ntohs(tvb, offset + 4) * 2;

      /* Message subtree */
      descriptor = val_to_str(descriptor_id, descriptors, "Unknown (%u)");
      if (descriptor_id == ACK)
            msg = proto_tree_add_none_format(tree,
                                     hf_armagetronad_msg_subtree,
                                     tvb, offset, data_len + 6,
                                     "ACK %d messages",
                                     data_len / 2);
      else
            msg = proto_tree_add_none_format(tree,
                                     hf_armagetronad_msg_subtree,
                                     tvb, offset, data_len + 6,
                                     "Message 0x%04x [%s]",
                                     message_id, descriptor);

      msg_tree = proto_item_add_subtree(msg, ett_message);

      /* DescriptorID field */
      proto_tree_add_item(msg_tree, hf_armagetronad_descriptor_id, tvb,
                      offset, 2, FALSE);
      if (info)
            g_string_append_printf(info, "%s, ", descriptor);

      /* MessageID field */
      proto_tree_add_item(msg_tree, hf_armagetronad_message_id, tvb,
                      offset + 2, 2, FALSE);

      /* DataLen field */
      proto_tree_add_item(msg_tree, hf_armagetronad_data_len, tvb,
                      offset + 4, 2, FALSE);

      /* Data field */
      add_message_data(tvb, offset + 6, data_len, msg_tree);

      return data_len + 6;
}

/* Code to actually dissect the packets */
static gint
dissect_armagetronad(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree)
{
      proto_item *ti;
      proto_tree *armagetronad_tree;
      guint16 sender;
      gint offset = 0;
      GString *info;

      if (!is_armagetronad_packet(tvb))
            return 0;

      info = check_col(pinfo->cinfo, COL_INFO) ? g_string_new("") : NULL;

      col_set_str(pinfo->cinfo, COL_PROTOCOL, "Armagetronad");

      if (info)
            col_clear(pinfo->cinfo, COL_INFO);

      ti = proto_tree_add_item(tree, proto_armagetronad, tvb, 0, -1, FALSE);
      armagetronad_tree = proto_item_add_subtree(ti, ett_armagetronad);

      /* For each message in the frame */
      while (tvb_length_remaining(tvb, offset) > 2)
            offset += add_message(tvb, offset, armagetronad_tree, info);

      /* After the messages, comes the SenderID */
      sender = tvb_get_ntohs(tvb, offset);
      proto_tree_add_item(ti, hf_armagetronad_sender_id, tvb, offset, 2,
                      FALSE);

      if (info) {
            gsize new_len = info->len - 2;      /* Remove the trailing ", " */
            if (new_len > 0)
                  g_string_truncate(info, new_len);
            else
                  g_string_assign(info, "No message");

            col_add_fstr(pinfo->cinfo, COL_INFO, "[%s] from 0x%04x",
                       info->str, sender);
            g_string_free(info, TRUE);
      }

      return offset + 2;
}

void proto_register_armagetronad(void)
{
      static hf_register_info hf[] = {
            {&hf_armagetronad_descriptor_id,
             {"Descriptor", "armagetronad.descriptor_id",
              FT_UINT16, BASE_DEC, VALS(descriptors), 0x0,
              "The ID of the descriptor (the command)", HFILL}
             },
            {&hf_armagetronad_message_id,
             {"MessageID", "armagetronad.message_id",
              FT_UINT16, BASE_HEX, NULL, 0x0,
              "The ID of the message (to ack it)", HFILL}
             },
            {&hf_armagetronad_data_len,
             {"DataLen", "armagetronad.data_len",
              FT_UINT16, BASE_DEC, NULL, 0x0,
              "The length of the data (in shorts)", HFILL}
             },
            {&hf_armagetronad_data,
             {"Data", "armagetronad.data",
              FT_STRING, BASE_NONE, NULL, 0x0,
              "The actual data (array of shorts in network order)", HFILL}
             },
            {&hf_armagetronad_sender_id,
             {"SenderID", "armagetronad.sender_id",
              FT_UINT16, BASE_HEX, NULL, 0x0,
              "The ID of the sender (0x0000 for the server)", HFILL}
             },
            {&hf_armagetronad_msg_subtree,
             {"Message", "armagetronad.message",
              FT_NONE, BASE_NONE, NULL, 0x0,
              "A message", HFILL}
             }
      };

      static gint *ett[] = {
            &ett_armagetronad,
            &ett_message
      };

      proto_armagetronad =
          proto_register_protocol("The Armagetron Advanced OpenGL Tron clone",
                            "Armagetronad", "armagetronad");

      proto_register_field_array(proto_armagetronad, hf, array_length(hf));
      proto_register_subtree_array(ett, array_length(ett));
      new_register_dissector("armagetronad", dissect_armagetronad,
                         proto_armagetronad);
}

void proto_reg_handoff_armagetronad(void)
{
      dissector_handle_t armagetronad_handle;

      armagetronad_handle = find_dissector("armagetronad");

      dissector_add("udp.port", UDP_PORT_ARMAGETRONAD, armagetronad_handle);
      dissector_add("udp.port", UDP_PORT_MASTER, armagetronad_handle);
}

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