/* packet-arcnet.c

 * Routines for arcnet dissection

 * Copyright 2001-2002, Peter Fales <ethereal@fales-lorenz.net>

 *

 * 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/capture_dissectors.h>

#include <epan/address_types.h>

#include <epan/arcnet_pids.h>

#include <epan/to_str.h>

#include "packet-ip.h"

#include "packet-arp.h"

void proto_register_arcnet(void);

void proto_reg_handoff_arcnet(void);

static dissector_handle_t arcnet_handle;

static dissector_handle_t arcnet_linux_handle;

static capture_dissector_handle_t arcnet_cap_handle;

static capture_dissector_handle_t arcnet_cap_has_ex_handle;

/* Initialize the protocol and registered fields */

static int proto_arcnet;

static int hf_arcnet_src;

static int hf_arcnet_dst;

static int hf_arcnet_offset;

static int hf_arcnet_protID;

static int hf_arcnet_exception_flag;

static int hf_arcnet_split_flag;

static int hf_arcnet_sequence;

static int hf_arcnet_padding;

/* Initialize the subtree pointers */

static int ett_arcnet;

static int arcnet_address_type = -1;

static dissector_table_t arcnet_dissector_table;

static capture_dissector_handle_t ip_cap_handle;

static capture_dissector_handle_t arp_cap_handle;

/* Cache protocol for packet counting */

static int proto_ipx;

static int arcnet_str_len(const address* addr _U_)

{

  return 5;

}

static int arcnet_to_str(const address* addr, char *buf, int buf_len _U_)

{

  *buf++ = '0';

  *buf++ = 'x';

  buf = bytes_to_hexstr(buf, (const uint8_t *)addr->data, 1);

  *buf = '\0'; /* NULL terminate */

  return arcnet_str_len(addr);

}

static const char* arcnet_col_filter_str(const address* addr _U_, bool is_src)

{

  if (is_src)

    return "arcnet.src";

  return "arcnet.dst";

}

static int arcnet_len(void)

{

  return 1;

}

static bool

capture_arcnet_common(const unsigned char *pd, int offset, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header, bool has_exception)

{

  if (!BYTES_ARE_IN_FRAME(offset, len, 1)) {

    return false;

  }

  switch (pd[offset]) {

  case ARCNET_PROTO_IP_1051:

    /* No fragmentation stuff in the header */

    return call_capture_dissector(ip_cap_handle, pd, offset + 1, len, cpinfo, pseudo_header);

  case ARCNET_PROTO_IP_1201:

    /*

     * There's fragmentation stuff in the header.

     *

     * XXX - on at least some versions of NetBSD, it appears that we

     * might we get ARCNET frames, not reassembled packets; we should

     * perhaps bump "counts->other" for all but the first frame of a packet.

     *

     * XXX - but on FreeBSD it appears that we get reassembled packets

     * on input (but apparently we get frames on output - or maybe

     * we get the packet *and* all its frames!); how to tell the

     * difference?  It looks from the FreeBSD reassembly code as if

     * the reassembled packet arrives with the header for the first

     * frame.  It also looks as if, on output, we first get the

     * full packet, with a header containing none of the fragmentation

     * stuff, and then get the frames.

     *

     * On Linux, we get only reassembled packets, and the exception

     * frame stuff is hidden - there's a split flag and sequence

     * number, but it appears that it will never have the exception

     * frame stuff.

     *

     * XXX - what about OpenBSD?  And, for that matter, what about

     * Windows?  (I suspect Windows supplies reassembled frames,

     * as WinPcap, like PF_PACKET sockets, taps into the networking

     * stack just as other protocols do.)

     */

    offset++;

    if (!BYTES_ARE_IN_FRAME(offset, len, 1)) {

      return false;

    }

    if (has_exception && pd[offset] == 0xff) {

      /* This is an exception packet.  The flag value there is the

         "this is an exception flag" packet; the next two bytes

         after it are padding, and another copy of the packet

         type appears after the padding. */

      offset += 4;

    }

    return call_capture_dissector(ip_cap_handle, pd, offset + 3, len, cpinfo, pseudo_header);

  case ARCNET_PROTO_ARP_1051:

  case ARCNET_PROTO_ARP_1201:

    /*

     * XXX - do we have to worry about fragmentation for ARP?

     */

    return call_capture_dissector(arp_cap_handle, pd, offset + 1, len, cpinfo, pseudo_header);

  case ARCNET_PROTO_IPX:

    capture_dissector_increment_count(cpinfo, proto_ipx);

    break;

  default:

    return false;

  }

  return true;

}

static bool

capture_arcnet (const unsigned char *pd, int offset _U_, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header)

{

  return capture_arcnet_common(pd, 4, len, cpinfo, pseudo_header, false);

}

static bool

capture_arcnet_has_exception(const unsigned char *pd, int offset _U_, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header)

{

  return capture_arcnet_common(pd, 2, len, cpinfo, pseudo_header, true);

}

static void

dissect_arcnet_common (tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree,

                       bool has_offset, bool has_exception)

{

  int offset = 0;

  uint8_t dst, src, protID, split_flag;

  tvbuff_t *next_tvb;

  proto_item *ti;

  proto_tree *arcnet_tree;

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

  col_set_str(pinfo->cinfo, COL_INFO, "ARCNET");

  src = tvb_get_uint8 (tvb, 0);

  dst = tvb_get_uint8 (tvb, 1);

  set_address_tvb(&pinfo->dl_src,   arcnet_address_type, 1, tvb, 0);

  copy_address_shallow(&pinfo->src, &pinfo->dl_src);

  set_address_tvb(&pinfo->dl_dst,   arcnet_address_type, 1, tvb, 1);

  copy_address_shallow(&pinfo->dst, &pinfo->dl_dst);

  ti = proto_tree_add_item (tree, proto_arcnet, tvb, 0, -1, ENC_NA);

  arcnet_tree = proto_item_add_subtree (ti, ett_arcnet);

  proto_tree_add_uint (arcnet_tree, hf_arcnet_src, tvb, offset, 1, src);

  offset++;

  proto_tree_add_uint (arcnet_tree, hf_arcnet_dst, tvb, offset, 1, dst);

  offset++;

  if (has_offset) {

    proto_tree_add_item (arcnet_tree, hf_arcnet_offset, tvb, offset, 2, ENC_NA);

    offset += 2;

  }

  protID = tvb_get_uint8 (tvb, offset);

  proto_tree_add_uint (arcnet_tree, hf_arcnet_protID, tvb, offset, 1, protID);

  offset++;

  switch (protID) {

  case ARCNET_PROTO_IP_1051:

  case ARCNET_PROTO_ARP_1051:

  case ARCNET_PROTO_DIAGNOSE:

  case ARCNET_PROTO_BACNET:     /* XXX - no fragmentation? */

    /* No fragmentation stuff in the header */

    break;

  default:

    /*

     * Show the fragmentation stuff - flag and sequence ID.

     *

     * XXX - on at least some versions of NetBSD, it appears that

     * we might get ARCNET frames, not reassembled packets; if so,

     * we should reassemble them.

     *

     * XXX - but on FreeBSD it appears that we get reassembled packets

     * on input (but apparently we get frames on output - or maybe

     * we get the packet *and* all its frames!); how to tell the

     * difference?  It looks from the FreeBSD reassembly code as if

     * the reassembled packet arrives with the header for the first

     * frame.  It also looks as if, on output, we first get the

     * full packet, with a header containing none of the fragmentation

     * stuff, and then get the frames.

     *

     * On Linux, we get only reassembled packets, and the exception

     * frame stuff is hidden - there's a split flag and sequence

     * number, but it appears that it will never have the exception

     * frame stuff.

     *

     * XXX - what about OpenBSD?  And, for that matter, what about

     * Windows?  (I suspect Windows supplies reassembled frames,

     * as WinPcap, like PF_PACKET sockets, taps into the networking

     * stack just as other protocols do.)

     */

    split_flag = tvb_get_uint8 (tvb, offset);

    if (has_exception && split_flag == 0xff) {

      /* This is an exception packet.  The flag value there is the

         "this is an exception flag" packet; the next two bytes

         after it are padding. */

      proto_tree_add_uint (arcnet_tree, hf_arcnet_exception_flag, tvb, offset, 1,

                           split_flag);

      offset++;

      proto_tree_add_item(arcnet_tree, hf_arcnet_padding, tvb, offset, 2, ENC_BIG_ENDIAN);

      offset += 2;

      /* Another copy of the packet type appears after the padding. */

      proto_tree_add_item (arcnet_tree, hf_arcnet_protID, tvb, offset, 1, ENC_BIG_ENDIAN);

      offset++;

      /* And after that comes the real split flag. */

      split_flag = tvb_get_uint8 (tvb, offset);

    }

    proto_tree_add_uint (arcnet_tree, hf_arcnet_split_flag, tvb, offset, 1,

                         split_flag);

    offset++;

    proto_tree_add_item (arcnet_tree, hf_arcnet_sequence, tvb, offset, 2, ENC_BIG_ENDIAN);

    offset += 2;

    break;

  }

  /* Set the length of the ARCNET header protocol tree item. */

  proto_item_set_len(ti, offset);

  next_tvb = tvb_new_subset_remaining (tvb, offset);

  if (!dissector_try_uint (arcnet_dissector_table, protID,

                           next_tvb, pinfo, tree))

    {

      col_add_fstr (pinfo->cinfo, COL_PROTOCOL, "0x%04x", protID);

      call_data_dissector(next_tvb, pinfo, tree);

    }

}

/*

 * BSD-style ARCNET headers - they don't have the offset field from the

 * ARCNET hardware packet, but we might get an exception frame header.

 */

static int

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

{

  dissect_arcnet_common (tvb, pinfo, tree, false, true);

  return tvb_captured_length(tvb);

}

/*

 * Linux-style ARCNET headers - they *do* have the offset field from the

 * ARCNET hardware packet, but we should never see an exception frame

 * header.

 */

static int

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

{

  dissect_arcnet_common (tvb, pinfo, tree, true, false);

  return tvb_captured_length(tvb);

}

static const value_string arcnet_prot_id_vals[] = {

  {ARCNET_PROTO_IP_1051,          "RFC 1051 IP"},

  {ARCNET_PROTO_ARP_1051,         "RFC 1051 ARP"},

  {ARCNET_PROTO_IP_1201,          "RFC 1201 IP"},

  {ARCNET_PROTO_ARP_1201,         "RFC 1201 ARP"},

  {ARCNET_PROTO_RARP_1201,        "RFC 1201 RARP"},

  {ARCNET_PROTO_IPX,              "IPX"},

  {ARCNET_PROTO_NOVELL_EC,        "Novell of some sort"},

  {ARCNET_PROTO_IPv6,             "IPv6"},

  {ARCNET_PROTO_ETHERNET,         "Encapsulated Ethernet"},

  {ARCNET_PROTO_DATAPOINT_BOOT,   "Datapoint boot"},

  {ARCNET_PROTO_DATAPOINT_MOUNT,  "Datapoint mount"},

  {ARCNET_PROTO_POWERLAN_BEACON,  "PowerLAN beacon"},

  {ARCNET_PROTO_POWERLAN_BEACON2, "PowerLAN beacon2"},

  {ARCNET_PROTO_APPLETALK,        "Appletalk"},

  {ARCNET_PROTO_BANYAN,           "Banyan VINES"},

  {ARCNET_PROTO_DIAGNOSE,         "Diagnose"},

  {ARCNET_PROTO_BACNET,           "BACnet"},

  {0,                             NULL}

};

void

proto_register_arcnet (void)

{

/* Setup list of header fields  See Section 1.6.1 for details*/

  static hf_register_info hf[] = {

    {&hf_arcnet_src,

     {"Source", "arcnet.src",

      FT_UINT8, BASE_HEX, NULL, 0,

      "Source ID", HFILL}

     },

    {&hf_arcnet_dst,

     {"Dest", "arcnet.dst",

      FT_UINT8, BASE_HEX, NULL, 0,

      "Dest ID", HFILL}

     },

    {&hf_arcnet_offset,

     {"Offset", "arcnet.offset",

      FT_BYTES, BASE_NONE, NULL, 0,

      NULL, HFILL}

     },

    {&hf_arcnet_protID,

     {"Protocol ID", "arcnet.protID",

      FT_UINT8, BASE_HEX, VALS(arcnet_prot_id_vals), 0,

      "Proto type", HFILL}

     },

    {&hf_arcnet_split_flag,

     {"Split Flag", "arcnet.split_flag",

      FT_UINT8, BASE_DEC, NULL, 0,

      NULL, HFILL}

     },

    {&hf_arcnet_exception_flag,

     {"Exception Flag", "arcnet.exception_flag",

      FT_UINT8, BASE_HEX, NULL, 0,

      NULL, HFILL}

     },

    {&hf_arcnet_sequence,

     {"Sequence", "arcnet.sequence",

      FT_UINT16, BASE_DEC, NULL, 0,

      "Sequence number", HFILL}

     },

    {&hf_arcnet_padding,

     {"Padding", "arcnet.padding",

      FT_UINT16, BASE_HEX, NULL, 0,

      NULL, HFILL}

     },

  };

/* Setup protocol subtree array */

  static int *ett[] = {

    &ett_arcnet,

  };

/* Register the protocol name and description */

  proto_arcnet = proto_register_protocol ("ARCNET", "ARCNET", "arcnet");

/* Required function calls to register the header fields and subtrees used */

  proto_register_field_array (proto_arcnet, hf, array_length (hf));

  proto_register_subtree_array (ett, array_length (ett));

  arcnet_dissector_table = register_dissector_table ("arcnet.protocol_id", "ARCNET Protocol ID",

                                                     proto_arcnet, FT_UINT8, BASE_HEX);

  arcnet_address_type = address_type_dissector_register("AT_ARCNET", "ARCNET Address", arcnet_to_str, arcnet_str_len, NULL, arcnet_col_filter_str, arcnet_len, NULL, NULL);

  arcnet_handle = register_dissector("arcnet", dissect_arcnet, proto_arcnet);

  arcnet_linux_handle = register_dissector("arcnet_linux", dissect_arcnet_linux, proto_arcnet);

  arcnet_cap_handle = register_capture_dissector("arcnet_linux", capture_arcnet, proto_arcnet);

  arcnet_cap_has_ex_handle = register_capture_dissector("arcnet", capture_arcnet_has_exception, proto_arcnet);

}

void

proto_reg_handoff_arcnet (void)

{

  dissector_add_uint ("wtap_encap", WTAP_ENCAP_ARCNET, arcnet_handle);

  dissector_add_uint ("wtap_encap", WTAP_ENCAP_ARCNET_LINUX, arcnet_linux_handle);

  proto_ipx = proto_get_id_by_filter_name("ipx");

  capture_dissector_add_uint("wtap_encap", WTAP_ENCAP_ARCNET_LINUX, arcnet_cap_handle);

  capture_dissector_add_uint("wtap_encap", WTAP_ENCAP_ARCNET, arcnet_cap_has_ex_handle);

  ip_cap_handle = find_capture_dissector("ip");

  arp_cap_handle = find_capture_dissector("arp");

}

/*

 * 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:

 */