/* packet-aarp.c

 * Routines for Appletalk ARP packet disassembly

 *

 * Simon Wilkinson <sxw@dcs.ed.ac.uk>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998

 *

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

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/etypes.h>

#include <epan/expert.h>

#include <epan/to_str.h>

/* Forward declarations */

void proto_register_aarp(void);

void proto_reg_handoff_aarp(void);

static int proto_aarp;

static int hf_aarp_hard_type;

static int hf_aarp_proto_type;

static int hf_aarp_hard_size;

static int hf_aarp_proto_size;

static int hf_aarp_opcode;

static int hf_aarp_src_hw;

static int hf_aarp_src_hw_mac;

static int hf_aarp_src_proto;

static int hf_aarp_src_proto_id;

static int hf_aarp_dst_hw;

static int hf_aarp_dst_hw_mac;

static int hf_aarp_dst_proto;

static int hf_aarp_dst_proto_id;

static int ett_aarp;

static expert_field ei_aarp_length_invalid;

#ifndef AARP_REQUEST

#define AARP_REQUEST    0x0001

#endif

#ifndef AARP_REPLY

#define AARP_REPLY      0x0002

#endif

#ifndef AARP_PROBE

#define AARP_PROBE      0x0003

#endif

/* The following is screwed up shit to deal with the fact that

   the linux kernel edits the packet inline. */

#define AARP_REQUEST_SWAPPED    0x0100

#define AARP_REPLY_SWAPPED  0x0200

#define AARP_PROBE_SWAPPED  0x0300

static const value_string op_vals[] = {

  {AARP_REQUEST,  "request" },

  {AARP_REPLY,    "reply"   },

  {AARP_PROBE,    "probe"   },

  {AARP_REQUEST_SWAPPED,  "request" },

  {AARP_REPLY_SWAPPED,    "reply"   },

  {AARP_PROBE_SWAPPED,    "probe"   },

  {0,             NULL           } };

/* AARP protocol HARDWARE identifiers. */

#define AARPHRD_ETHER   1               /* Ethernet 10Mbps              */

#define AARPHRD_TR      2               /* Token Ring                   */

static const value_string hrd_vals[] = {

  {AARPHRD_ETHER,   "Ethernet"       },

  {AARPHRD_TR,      "Token Ring"     },

  {0,               NULL             } };

/*

 * Given the hardware address type and length, check whether an address

 * is an Ethernet address - the address must be of type "Ethernet" or

 * "Token Ring", and the length must be 6 bytes.

 */

#define AARP_HW_IS_ETHER(ar_hrd, ar_hln) \

        (((ar_hrd) == AARPHRD_ETHER || (ar_hrd) == AARPHRD_TR) \

                                && (ar_hln) == 6)

/*

 * Given the protocol address type and length, check whether an address

 * is an Appletalk address - the address must be of type "Appletalk",

 * and the length must be 4 bytes.

 */

#define AARP_PRO_IS_ATALK(ar_pro, ar_pln) \

        ((ar_pro) == ETHERTYPE_ATALK && (ar_pln) == 4)

static char *

tvb_atalkid_to_str(wmem_allocator_t *scope, tvbuff_t *tvb, unsigned offset)

{

  unsigned node;

  char *cur;

  cur=(char *)wmem_alloc(scope, 16);

  node=tvb_get_uint8(tvb, offset+1)<<8|tvb_get_uint8(tvb, offset+2);

  snprintf(cur, 16, "%u.%u", node, tvb_get_uint8(tvb, offset+3));

  return cur;

}

static const char *

tvb_aarphrdaddr_to_str(wmem_allocator_t *scope, tvbuff_t *tvb, unsigned offset, unsigned ad_len, uint16_t type)

{

  if (AARP_HW_IS_ETHER(type, ad_len)) {

    /* Ethernet address (or Token Ring address, which is the same type

       of address). */

    return tvb_ether_to_str(scope, tvb, offset);

  }

  return tvb_bytes_to_str(scope, tvb, offset, ad_len);

}

static char *

tvb_aarpproaddr_to_str(wmem_allocator_t *scope, tvbuff_t *tvb, unsigned offset, unsigned ad_len, uint16_t type)

{

  if (AARP_PRO_IS_ATALK(type, ad_len)) {

    /* Appletalk address.  */

    return tvb_atalkid_to_str(scope, tvb, offset);

  }

  return tvb_bytes_to_str(scope, tvb, offset, ad_len);

}

/* Offsets of fields within an AARP packet. */

#define AR_HRD          0

#define AR_PRO          2

#define AR_HLN          4

#define AR_PLN          5

#define AR_OP           6

#define MIN_AARP_HEADER_SIZE    8

static int

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

  uint16_t    ar_hrd;

  uint16_t    ar_pro;

  uint8_t     ar_hln;

  uint8_t     ar_pln;

  uint16_t    ar_op;

  proto_tree  *aarp_tree;

  proto_item  *ti;

  const char *op_str;

  unsigned    sha_offset, spa_offset, tha_offset, tpa_offset;

  const char *sha_str, *spa_str, /* *tha_str, */ *tpa_str;

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

  col_clear(pinfo->cinfo, COL_INFO);

  ar_hrd = tvb_get_ntohs(tvb, AR_HRD);

  ar_pro = tvb_get_ntohs(tvb, AR_PRO);

  ar_hln = tvb_get_uint8(tvb, AR_HLN);

  ar_pln = tvb_get_uint8(tvb, AR_PLN);

  ar_op  = tvb_get_ntohs(tvb, AR_OP);

  /* Get the offsets of the addresses. */

  sha_offset = MIN_AARP_HEADER_SIZE;

  spa_offset = sha_offset + ar_hln;

  tha_offset = spa_offset + ar_pln;

  tpa_offset = tha_offset + ar_hln;

  /* Extract the addresses.  */

  if (ar_hln < 1) {

    expert_add_info_format(pinfo, tree, &ei_aarp_length_invalid,

      "Invalid hardware address length: %d", ar_hln);

    sha_str = "Unknown";

#if 0

    tha_str = "Unknown";

#endif

  } else {

    sha_str = tvb_aarphrdaddr_to_str(pinfo->pool, tvb, sha_offset, ar_hln, ar_hrd);

#if 0

    /* TODO: tha_str is currently not shown nor parsed */

    tha_str = tvb_aarphrdaddr_to_str(pinfo->pool, tvb, tha_offset, ar_hln, ar_hrd);

#endif

  }

  if (ar_pln < 1) {

    expert_add_info_format(pinfo, tree, &ei_aarp_length_invalid,

      "Invalid protocol address length: %d", ar_pln);

    spa_str = "Unknown";

    tpa_str = "Unknown";

  } else {

    spa_str = tvb_aarpproaddr_to_str(pinfo->pool, tvb, spa_offset, ar_pln, ar_pro);

    tpa_str = tvb_aarpproaddr_to_str(pinfo->pool, tvb, tpa_offset, ar_pln, ar_pro);

  }

  switch (ar_op) {

    case AARP_REQUEST:

    case AARP_REQUEST_SWAPPED:

      col_add_fstr(pinfo->cinfo, COL_INFO, "Who has %s?  Tell %s", tpa_str, spa_str);

      break;

    case AARP_REPLY:

    case AARP_REPLY_SWAPPED:

      col_add_fstr(pinfo->cinfo, COL_INFO, "%s is at %s", spa_str, sha_str);

      break;

    case AARP_PROBE:

    case AARP_PROBE_SWAPPED:

      col_add_fstr(pinfo->cinfo, COL_INFO, "Is there a %s", tpa_str);

      break;

    default:

      col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown AARP opcode 0x%04x", ar_op);

      break;

  }

  if (tree) {

    if ((op_str = try_val_to_str(ar_op, op_vals)))

      ti = proto_tree_add_protocol_format(tree, proto_aarp, tvb, 0,

                                      MIN_AARP_HEADER_SIZE + 2*ar_hln +

                                      2*ar_pln, "AppleTalk Address Resolution Protocol (%s)", op_str);

    else

      ti = proto_tree_add_protocol_format(tree, proto_aarp, tvb, 0,

                                      MIN_AARP_HEADER_SIZE + 2*ar_hln +

                                      2*ar_pln,

                                      "AppleTalk Address Resolution Protocol (opcode 0x%04x)", ar_op);

    aarp_tree = proto_item_add_subtree(ti, ett_aarp);

    proto_tree_add_uint(aarp_tree, hf_aarp_hard_type, tvb, AR_HRD, 2,

                               ar_hrd);

    proto_tree_add_uint(aarp_tree, hf_aarp_proto_type, tvb, AR_PRO, 2,

                               ar_pro);

    proto_tree_add_uint(aarp_tree, hf_aarp_hard_size, tvb, AR_HLN, 1,

                               ar_hln);

    proto_tree_add_uint(aarp_tree, hf_aarp_proto_size, tvb, AR_PLN, 1,

                               ar_pln);

    proto_tree_add_uint(aarp_tree, hf_aarp_opcode, tvb, AR_OP, 2,

                               ar_op);

    if (ar_hln != 0) {

      proto_tree_add_item(aarp_tree,

        AARP_HW_IS_ETHER(ar_hrd, ar_hln) ? hf_aarp_src_hw_mac : hf_aarp_src_hw,

        tvb, sha_offset, ar_hln, ENC_NA);

    }

    if (ar_pln != 0) {

      if (AARP_PRO_IS_ATALK(ar_pro, ar_pln)) {

        proto_tree_add_bytes_format_value(aarp_tree, hf_aarp_src_proto_id, tvb,

                                          spa_offset, ar_pln, NULL,

                                          "%s", spa_str);

      } else {

        proto_tree_add_bytes_format_value(aarp_tree, hf_aarp_src_proto, tvb,

                                          spa_offset, ar_pln, NULL,

                                          "%s", spa_str);

      }

    }

    if (ar_hln != 0) {

      proto_tree_add_item(aarp_tree,

        AARP_HW_IS_ETHER(ar_hrd, ar_hln) ? hf_aarp_dst_hw_mac : hf_aarp_dst_hw,

        tvb, tha_offset, ar_hln, ENC_NA);

    }

    if (ar_pln != 0) {

      if (AARP_PRO_IS_ATALK(ar_pro, ar_pln)) {

        proto_tree_add_bytes_format_value(aarp_tree, hf_aarp_dst_proto_id, tvb,

                                          tpa_offset, ar_pln,

                                          NULL, "%s", tpa_str);

      } else {

        proto_tree_add_bytes_format_value(aarp_tree, hf_aarp_dst_proto, tvb,

                                          tpa_offset, ar_pln,

                                          NULL, "%s", tpa_str);

      }

    }

  }

  return tvb_captured_length(tvb);

}

void

proto_register_aarp(void)

{

  static hf_register_info hf[] = {

    { &hf_aarp_hard_type,

      { "Hardware type",                "aarp.hard.type",

        FT_UINT16,      BASE_HEX,       VALS(hrd_vals), 0x0,

        NULL, HFILL }},

    { &hf_aarp_proto_type,

      { "Protocol type",                "aarp.proto.type",

        FT_UINT16,      BASE_HEX,       VALS(etype_vals),       0x0,

        NULL, HFILL }},

    { &hf_aarp_hard_size,

      { "Hardware size",                "aarp.hard.size",

        FT_UINT8,       BASE_DEC,       NULL,   0x0,

        NULL, HFILL }},

    { &hf_aarp_proto_size,

      { "Protocol size",                "aarp.proto.size",

        FT_UINT8,       BASE_DEC,       NULL,   0x0,

        NULL, HFILL }},

    { &hf_aarp_opcode,

      { "Opcode",                       "aarp.opcode",

        FT_UINT16,      BASE_DEC,       VALS(op_vals),  0x0,

        NULL, HFILL }},

    { &hf_aarp_src_hw,

      { "Sender hardware address",      "aarp.src.hw",

        FT_BYTES,       BASE_NONE,      NULL,   0x0,

        NULL, HFILL }},

    { &hf_aarp_src_hw_mac,

      { "Sender MAC address",           "aarp.src.hw_mac",

        FT_ETHER,       BASE_NONE,      NULL,   0x0,

        NULL, HFILL }},

    { &hf_aarp_src_proto,

      { "Sender protocol address",      "aarp.src.proto",

        FT_BYTES,       BASE_NONE,      NULL,   0x0,

        NULL, HFILL }},

    { &hf_aarp_src_proto_id,

      { "Sender ID",                    "aarp.src.proto_id",

        FT_BYTES,       BASE_NONE,      NULL,   0x0,

        NULL, HFILL }},

    { &hf_aarp_dst_hw,

      { "Target hardware address",      "aarp.dst.hw",

        FT_BYTES,       BASE_NONE,      NULL,   0x0,

        NULL, HFILL }},

    { &hf_aarp_dst_hw_mac,

      { "Target MAC address",           "aarp.dst.hw_mac",

        FT_ETHER,       BASE_NONE,      NULL,   0x0,

        NULL, HFILL }},

    { &hf_aarp_dst_proto,

      { "Target protocol address",      "aarp.dst.proto",

        FT_BYTES,       BASE_NONE,      NULL,   0x0,

      NULL, HFILL }},

    { &hf_aarp_dst_proto_id,

      { "Target ID",                    "aarp.dst.proto_id",

        FT_BYTES,       BASE_NONE,      NULL,   0x0,

        NULL, HFILL }},

  };

  static int *ett[] = {

    &ett_aarp,

  };

  static ei_register_info ei[] = {

    { &ei_aarp_length_invalid, { "aarp.length.invalid", PI_PROTOCOL, PI_WARN, "Invalid length", EXPFILL }},

  };

  proto_aarp = proto_register_protocol("Appletalk Address Resolution Protocol",

                                       "AARP",

                                       "aarp");

  register_dissector("aarp", dissect_aarp, proto_aarp);

  proto_register_field_array(proto_aarp, hf, array_length(hf));

  proto_register_subtree_array(ett, array_length(ett));

  expert_module_t* expert_aarp = expert_register_protocol(proto_aarp);

  expert_register_field_array(expert_aarp, ei, array_length(ei));

}

void

proto_reg_handoff_aarp(void)

{

  dissector_handle_t aarp_handle = find_dissector("aarp");

  dissector_add_uint("ethertype", ETHERTYPE_AARP, aarp_handle);

  dissector_add_uint("chdlc.protocol", ETHERTYPE_AARP, aarp_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:

 */