/* packet-rudp.c

 * Routines for Reliable UDP Protocol.

 * Copyright 2004, Duncan Sargeant <dunc-ethereal@rcpt.to>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

 * Copied from packet-data.c, README.developer, and various other files.

 *

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

 * Reliable UDP is a lightweight protocol for providing TCP-like flow

 * control over UDP.  Cisco published an PFC a long time ago, and

 * their actual implementation is slightly different, having no

 * checksum field.

 *

 * I've cheated here - RUDP could be used for anything, but I've only

 * seen it used to switched telephony calls, so we just call the Cisco SM

 * dissector from here.

 *

 * Here are some links:

 *

 * http://www.watersprings.org/pub/id/draft-ietf-sigtran-reliable-udp-00.txt

 * http://www.javvin.com/protocolRUDP.html

 * http://www.cisco.com/univercd/cc/td/doc/product/access/sc/rel7/omts/omts_apb.htm#30052

 */

#include "config.h"

#include <epan/packet.h>

void proto_register_rudp(void);

void proto_reg_handoff_rudp(void);

static dissector_handle_t rudp_handle;

static int proto_rudp;

static int hf_rudp_flags;

static int hf_rudp_flags_syn;

static int hf_rudp_flags_ack;

static int hf_rudp_flags_eak;

static int hf_rudp_flags_rst;

static int hf_rudp_flags_nul;

static int hf_rudp_flags_chk;

static int hf_rudp_flags_tcs;

static int hf_rudp_flags_0;

static int hf_rudp_hlen;

static int hf_rudp_seq;

static int hf_rudp_ack;

static int hf_rudp_cksum;

static int ett_rudp;

static int ett_rudp_flags;

static dissector_handle_t sm_handle;

static int

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

{

  tvbuff_t * next_tvb;

  proto_tree *rudp_tree;

  proto_item *ti;

  uint8_t hlen;

  static int * const flags[] = {

    &hf_rudp_flags_syn,

    &hf_rudp_flags_ack,

    &hf_rudp_flags_eak,

    &hf_rudp_flags_rst,

    &hf_rudp_flags_nul,

    &hf_rudp_flags_chk,

    &hf_rudp_flags_tcs,

    &hf_rudp_flags_0,

    NULL

  };

  hlen = tvb_get_uint8(tvb, 1);

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

  col_clear(pinfo->cinfo, COL_INFO);

  ti = proto_tree_add_item(tree, proto_rudp, tvb, 0, hlen, ENC_NA);

  rudp_tree = proto_item_add_subtree(ti, ett_rudp);

  proto_tree_add_bitmask(rudp_tree, tvb, 0, hf_rudp_flags, ett_rudp_flags, flags, ENC_BIG_ENDIAN);

  proto_tree_add_item(rudp_tree, hf_rudp_hlen, tvb, 1, 1, ENC_BIG_ENDIAN);

  proto_tree_add_item(rudp_tree, hf_rudp_seq, tvb, 2, 1, ENC_BIG_ENDIAN);

  proto_tree_add_item(rudp_tree, hf_rudp_ack, tvb, 3, 1, ENC_BIG_ENDIAN);

  /* If the header is more than 4 bytes the next 2 bytes are the checksum */

  if (hlen > 4) {

    proto_tree_add_checksum(rudp_tree, tvb, 4, hf_rudp_cksum, -1, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);

  }

  /* If we have even more bytes their meaning is unknown - we have seen this

    * in live captures */

  if (hlen > 6) {

    next_tvb = tvb_new_subset_length(tvb, 6, hlen-6);

    call_data_dissector(next_tvb, pinfo, rudp_tree);

  }

  next_tvb = tvb_new_subset_remaining(tvb, hlen);

  if (tvb_captured_length(next_tvb) && sm_handle)

    call_dissector(sm_handle, next_tvb, pinfo, tree);

  return tvb_captured_length(tvb);

}

void

proto_register_rudp(void)

{

  static hf_register_info hf[] = {

    { &hf_rudp_flags,

      { "RUDP Header flags",           "rudp.flags",

      FT_UINT8, BASE_DEC, NULL, 0x0,

      NULL, HFILL }

    },

    { &hf_rudp_flags_syn,

      { "Syn",           "rudp.flags.syn",

      FT_BOOLEAN, 8, NULL, 0x80,

      NULL, HFILL }

    },

    { &hf_rudp_flags_ack,

      { "Ack",           "rudp.flags.ack",

      FT_BOOLEAN, 8, NULL, 0x40,

      NULL, HFILL }

    },

    { &hf_rudp_flags_eak,

      { "Eak",           "rudp.flags.eak",

      FT_BOOLEAN, 8, NULL, 0x20,

      "Extended Ack", HFILL }

    },

    { &hf_rudp_flags_rst,

      { "RST",           "rudp.flags.rst",

      FT_BOOLEAN, 8, NULL, 0x10,

      "Reset flag", HFILL }

    },

    { &hf_rudp_flags_nul,

      { "NULL",           "rudp.flags.nul",

      FT_BOOLEAN, 8, NULL, 0x08,

      "Null flag", HFILL }

    },

    { &hf_rudp_flags_chk,

      { "CHK",           "rudp.flags.chk",

      FT_BOOLEAN, 8, NULL, 0x04,

      "Checksum is on header or body", HFILL }

    },

    { &hf_rudp_flags_tcs,

      { "TCS",           "rudp.flags.tcs",

      FT_BOOLEAN, 8, NULL, 0x02,

      "Transfer Connection System", HFILL }

    },

    { &hf_rudp_flags_0,

      { "0",           "rudp.flags.0",

      FT_BOOLEAN, 8, NULL, 0x01,

      NULL, HFILL }

    },

    { &hf_rudp_hlen,

      { "Header Length",           "rudp.hlen",

      FT_UINT8, BASE_DEC, NULL, 0x0,

      NULL, HFILL }

    },

    { &hf_rudp_seq,

      { "Seq",           "rudp.seq",

      FT_UINT8, BASE_DEC, NULL, 0x0,

      "Sequence Number", HFILL }

    },

    { &hf_rudp_ack,

      { "Ack",           "rudp.ack",

      FT_UINT8, BASE_DEC, NULL, 0x0,

      "Acknowledgement Number", HFILL }

    },

    { &hf_rudp_cksum,

      { "Checksum",           "rudp.cksum",

      FT_UINT16, BASE_HEX, NULL, 0x0,

      NULL, HFILL }

    },

  };

/* Setup protocol subtree array */

  static int *ett[] = {

    &ett_rudp,

    &ett_rudp_flags,

  };

  proto_rudp = proto_register_protocol ("Reliable UDP", "RUDP", "rudp");

  proto_register_field_array(proto_rudp, hf, array_length(hf));

  proto_register_subtree_array(ett, array_length(ett));

  rudp_handle = register_dissector("rudp", dissect_rudp, proto_rudp);

}

void

proto_reg_handoff_rudp(void) {

/* Disable rudp by default. The previously hardcoded value of

 * 7000 (used by Cisco) collides with afs and as the draft states:

 * "RUDP doesn't place any restrictions on which UDP port numbers are used.

 *  Valid port numbers are ports not defined in RFC 1700."

 */

/* FIXME: The proper solution would be to convert this dissector into

 *        heuristic dissector, but it isn't complete anyway.

 */

  dissector_add_for_decode_as_with_preference("udp.port", rudp_handle);

  sm_handle = find_dissector_add_dependency("sm", proto_rudp);

}

/*

 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html

 *

 * Local variables:

 * c-basic-offset: 8

 * tab-width: 8

 * indent-tabs-mode: t

 * End:

 *

 * vi: set shiftwidth=8 tabstop=8 noexpandtab:

 * :indentSize=8:tabSize=8:noTabs=false:

 */