/*
 * Copyright (c) 2003 Markus Friedl.  All rights reserved.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/ipproto.h>
#include <epan/expert.h>

void proto_register_etherip(void);
void proto_reg_handoff_etherip(void);

static int proto_etherip = -1;
static int hf_etherip_ver = -1;
static int hf_etherip_reserved = -1;

static gint ett_etherip = -1;

static expert_field ei_etherip_ver_3 = EI_INIT;
static expert_field ei_etherip_reserved_0 = EI_INIT;

static dissector_handle_t eth_withoutfcs_handle;
static dissector_handle_t etherip_handle;

/*
 * RFC 3378: EtherIP: Tunneling Ethernet Frames in IP Datagrams
 *
 *      Bits 0-3:  Protocol version
 *      Bits 4-15: Reserved for future use
 */

#define ETHERIP_VERS_MASK    0xF000
#define ETHERIP_RESERVE_MASK 0x0FFF


static int
dissect_etherip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
  tvbuff_t *next_tvb;
  proto_tree *etherip_tree;
  proto_item *ti;
  guint16 field, version;

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

  field = tvb_get_ntohs(tvb, 0);
  version = (field & ETHERIP_VERS_MASK) >> 12;

  if (tree) {
    ti = proto_tree_add_protocol_format(tree, proto_etherip, tvb, 0,
             2,
             "EtherIP, Version %d",
             version
             );
    etherip_tree = proto_item_add_subtree(ti, ett_etherip);

    ti = proto_tree_add_item(etherip_tree, hf_etherip_ver, tvb,
             0, 2, ENC_BIG_ENDIAN);
    if (version != 3) {
      expert_add_info(pinfo, ti, &ei_etherip_ver_3);
    }

    ti = proto_tree_add_item(etherip_tree, hf_etherip_reserved, tvb,
             0, 2, ENC_BIG_ENDIAN);
    if ((field & ETHERIP_RESERVE_MASK) != 0) {
      expert_add_info(pinfo, ti, &ei_etherip_reserved_0);
    }
  }

  /* Set the tvbuff for the payload after the header */
  next_tvb = tvb_new_subset_remaining(tvb, 2);

  call_dissector(eth_withoutfcs_handle, next_tvb, pinfo, tree);
  return tvb_captured_length(tvb);
}

void
proto_register_etherip(void)
{
  static hf_register_info hf_etherip[] = {
    { &hf_etherip_ver,
      { "Version", "etherip.ver", FT_UINT16, BASE_DEC, NULL, ETHERIP_VERS_MASK,
        NULL, HFILL }},
    { &hf_etherip_reserved,
      { "Reserved", "etherip.reserved", FT_UINT16, BASE_HEX, NULL, ETHERIP_RESERVE_MASK,
        "Reserved (must be 0)", HFILL }},
  };

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

  static ei_register_info ei[] = {
     { &ei_etherip_ver_3, { "etherip.ver.not3", PI_PROTOCOL, PI_WARN, "Version must be 3", EXPFILL }},
     { &ei_etherip_reserved_0, { "etherip.reserved.not0", PI_PROTOCOL, PI_WARN, "Reserved field must be 0", EXPFILL }},
  };

  expert_module_t* expert_etherip;

  proto_etherip = proto_register_protocol("Ethernet over IP",
                                          "ETHERIP", "etherip");
  proto_register_field_array(proto_etherip, hf_etherip, array_length(hf_etherip));
  proto_register_subtree_array(ett, array_length(ett));
  expert_etherip = expert_register_protocol(proto_etherip);
  expert_register_field_array(expert_etherip, ei, array_length(ei));

  etherip_handle = register_dissector("etherip", dissect_etherip, proto_etherip);
}

void
proto_reg_handoff_etherip(void)
{
  eth_withoutfcs_handle = find_dissector_add_dependency("eth_withoutfcs", proto_etherip);
  dissector_add_uint("ip.proto", IP_PROTO_ETHERIP, etherip_handle);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local Variables:
 * c-basic-offset: 2
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * ex: set shiftwidth=2 tabstop=8 expandtab:
 * :indentSize=2:tabSize=8:noTabs=true:
 */
