/* packet-db-lsp.c

 * Routines for Dropbox LAN sync Protocol

 *

 * Copyright 2010, Stig Bjorlykke <stig@bjorlykke.org>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

 * SPDX-License-Identifier: GPL-2.0-or-later

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/asn1.h>

#include <epan/prefs.h>

#include "packet-tcp.h"

#include "packet-x509af.h"

#define DB_LSP_PORT  17500

void proto_register_db_lsp(void);

void proto_reg_handoff_db_lsp(void);

static int proto_db_lsp;

static int proto_db_lsp_disc;

static int hf_type;

static int hf_magic;

static int hf_length;

static int hf_opvalue;

static int hf_data;

static int hf_value;

static int hf_text;

static int ett_db_lsp;

static heur_dissector_list_t heur_subdissector_list;

static dissector_handle_t db_lsp_tcp_handle;

static dissector_handle_t db_lsp_udp_handle;

/* Use heuristic */

static bool try_heuristic = true;

/* desegmentation of tcp payload */

static bool db_lsp_desegment = true;

#define TYPE_CONFIG   0x16

#define TYPE_DATA     0x17

static const value_string type_vals[] = {

  { TYPE_CONFIG,    "Configuration" },

  { TYPE_DATA,      "Data" },

  { 0, NULL }

};

#define OP_CERT       0x0B

static const value_string op_vals[] = {

  { OP_CERT,   "Certificate" },

  { 0, NULL }

};

static int

dissect_db_lsp_pdu (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

  proto_tree *db_lsp_tree;

  proto_item *db_lsp_item;

  int         offset = 0;

  uint8_t     type, opvalue;

  uint16_t    magic, length;

  col_set_str (pinfo->cinfo, COL_PROTOCOL, "DB-LSP");

  col_set_str (pinfo->cinfo, COL_INFO, "Dropbox LAN sync Protocol");

  db_lsp_item = proto_tree_add_item (tree, proto_db_lsp, tvb, offset, -1, ENC_NA);

  db_lsp_tree = proto_item_add_subtree (db_lsp_item, ett_db_lsp);

  proto_tree_add_item_ret_uint8 (db_lsp_tree, hf_type, tvb, offset, 1, ENC_BIG_ENDIAN, &type);

  offset += 1;

  if (type == 0x80) {

    /* Two unknown bytes */

    offset += 2;

  }

  proto_tree_add_item_ret_uint16 (db_lsp_tree, hf_magic, tvb, offset, 2, ENC_BIG_ENDIAN, &magic);

  offset += 2;

  proto_tree_add_item_ret_uint16 (db_lsp_tree, hf_length, tvb, offset, 2, ENC_BIG_ENDIAN, &length);

  offset += 2;

  if (magic != 0x0301 || length > tvb_reported_length_remaining (tvb, offset)) {

    /* Probably an unknown packet */

    /* expert_add_info_format (pinfo, db_lsp_item, PI_UNDECODED, PI_WARN, "Unknown packet"); */

    return 0;

  }

  if (type == TYPE_CONFIG) {

    proto_tree_add_item_ret_uint8 (db_lsp_tree, hf_opvalue, tvb, offset, 1, ENC_BIG_ENDIAN, &opvalue);

    if (opvalue == OP_CERT && length >= 10) {

      /* X509 Certificate, after 10 octets */

      tvbuff_t *cert_tvb = tvb_new_subset_length (tvb, offset+10, length-10);

      dissect_x509af_Certificate_PDU (cert_tvb, pinfo, db_lsp_tree, NULL);

    } else {

      proto_tree_add_item (db_lsp_tree, hf_value, tvb, offset, length, ENC_NA);

    }

  } else if (type == TYPE_DATA) {

    proto_tree_add_item (db_lsp_tree, hf_data, tvb, offset, length, ENC_NA);

  } else {

    proto_tree_add_item (db_lsp_tree, hf_value, tvb, offset, length, ENC_NA);

  }

  /*offset += length;*/

  proto_item_append_text (db_lsp_item, ", Type: %d, Length: %d", type, length);

  proto_item_set_len (db_lsp_item, length + 5);

  return tvb_reported_length(tvb);

}

static unsigned

get_db_lsp_pdu_len (packet_info *pinfo _U_, tvbuff_t *tvb,

                    int offset, void *data _U_)

{

  if (tvb_get_ntohs (tvb, offset + 1) != 0x0301) {

    /* Unknown data, eat remaining data for this frame */

    return tvb_reported_length_remaining (tvb, offset);

  }

  return tvb_get_ntohs (tvb, offset + 3) + 5;

}

static int

dissect_db_lsp_tcp (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)

{

  tcp_dissect_pdus (tvb, pinfo, tree, db_lsp_desegment, 5,

                    get_db_lsp_pdu_len, dissect_db_lsp_pdu, data);

  return tvb_reported_length(tvb);

}

static int

dissect_db_lsp_disc (tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

  proto_tree *db_lsp_tree;

  proto_item *db_lsp_item;

  int         offset = 0;

  heur_dtbl_entry_t *hdtbl_entry;

  proto_tree *data_subtree;

  col_set_str (pinfo->cinfo, COL_PROTOCOL, "DB-LSP-DISC");

  col_set_str (pinfo->cinfo, COL_INFO, "Dropbox LAN sync Discovery Protocol");

  db_lsp_item = proto_tree_add_item (tree, proto_db_lsp_disc, tvb, offset, -1, ENC_NA);

  db_lsp_tree = proto_item_add_subtree (db_lsp_item, ett_db_lsp);

  /* try the heuristic dissectors */

  if (try_heuristic) {

    data_subtree = proto_item_add_subtree(db_lsp_item, ett_db_lsp);

    if (dissector_try_heuristic(heur_subdissector_list, tvb, pinfo, data_subtree, &hdtbl_entry, NULL)) {

      return tvb_captured_length(tvb);

    }

  }

  /* heuristic failed. Print remaining bytes as text */

  proto_tree_add_item (db_lsp_tree, hf_text, tvb, offset, -1, ENC_ASCII);

  return tvb_captured_length(tvb);

}

void

proto_register_db_lsp (void)

{

  static hf_register_info hf[] = {

    { &hf_type,

      { "Type", "db-lsp.type",

        FT_UINT8, BASE_DEC_HEX, VALS(type_vals), 0x0,

        NULL, HFILL } },

    { &hf_magic,

      { "Magic", "db-lsp.magic",

        FT_UINT16, BASE_DEC_HEX, NULL, 0x0,

        "Magic number", HFILL } },

    { &hf_length,

      { "Length", "db-lsp.length",

        FT_UINT16, BASE_DEC_HEX, NULL, 0x0,

        "Length in bytes", HFILL } },

    { &hf_opvalue,

      { "OP Value", "db-lsp.op",

        FT_UINT8, BASE_DEC_HEX, VALS(op_vals), 0x0,

        NULL, HFILL } },

    { &hf_value,

      { "Value", "db-lsp.value",

        FT_BYTES, BASE_NONE, NULL, 0x0,

        NULL, HFILL } },

    { &hf_data,

      { "Data", "db-lsp.data",

        FT_BYTES, BASE_NONE, NULL, 0x0,

        NULL, HFILL } },

    { &hf_text,

      { "Text", "db-lsp.text",

        FT_STRING, BASE_NONE, NULL, 0x0,

        NULL, HFILL } },

  };

  static int *ett[] = {

    &ett_db_lsp,

  };

  module_t *db_lsp_module;

  proto_db_lsp = proto_register_protocol ("Dropbox LAN sync Protocol", "DB-LSP", "db-lsp");

  proto_db_lsp_disc = proto_register_protocol ("Dropbox LAN sync Discovery Protocol", "DB-LSP-DISC", "db-lsp-disc");

  db_lsp_tcp_handle = register_dissector ("db-lsp.tcp", dissect_db_lsp_tcp, proto_db_lsp);

  db_lsp_udp_handle = register_dissector ("db-lsp.udp", dissect_db_lsp_disc, proto_db_lsp_disc);

  heur_subdissector_list = register_heur_dissector_list_with_description("db-lsp", "DB-LSP-DISC payload", proto_db_lsp);

  proto_register_field_array (proto_db_lsp, hf, array_length (hf));

  proto_register_subtree_array (ett, array_length (ett));

  /* Register our configuration options */

  db_lsp_module = prefs_register_protocol (proto_db_lsp, NULL);

  prefs_register_bool_preference (db_lsp_module, "desegment_pdus",

                                  "Reassemble PDUs spanning multiple TCP segments",

                                  "Whether the LAN sync dissector should reassemble PDUs"

                                  " spanning multiple TCP segments."

                                  " To use this option, you must also enable \"Allow subdissectors"

                                  " to reassemble TCP streams\" in the TCP protocol settings.",

                                  &db_lsp_desegment);

  prefs_register_bool_preference(db_lsp_module, "try_heuristic",

                                  "Try heuristic sub-dissectors",

                                  "Try to decode the payload using an heuristic sub-dissector",

                                  &try_heuristic);

}

void

proto_reg_handoff_db_lsp (void)

{

  dissector_add_uint_with_preference("tcp.port", DB_LSP_PORT, db_lsp_tcp_handle);

  dissector_add_uint_with_preference("udp.port", DB_LSP_PORT, db_lsp_udp_handle);

}

/*

 * Editor modelines

 *

 * Local Variables:

 * c-basic-offset: 2

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 * indent-tabs-mode: nil

 * End:

 *

 * ex: set shiftwidth=2 tabstop=8 expandtab:

 * :indentSize=2:tabSize=8:noTabs=true:

 */