epan/dissectors/packet-aarp.c

   1 /* packet-aarp.c
   2  * Routines for Appletalk ARP packet disassembly
   3  *
   4  * $Id$
   5  *
   6  * Simon Wilkinson <sxw@dcs.ed.ac.uk>
   7  *
   8  * Wireshark - Network traffic analyzer
   9  * By Gerald Combs <gerald@wireshark.org>
  10  * Copyright 1998
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  25  */
  26
  27 #include "config.h"
  28
  29 #include <epan/packet.h>
  30 #include <epan/strutil.h>
  31 #include <epan/wmem/wmem.h>
  32 #include <epan/etypes.h>
  33 #include <epan/to_str.h>
  34
  35 /* Forward declarations */
  36 void proto_register_aarp(void);
  37 void proto_reg_handoff_aarp(void);
  38
  39 static int proto_aarp = -1;
  40 static int hf_aarp_hard_type = -1;
  41 static int hf_aarp_proto_type = -1;
  42 static int hf_aarp_hard_size = -1;
  43 static int hf_aarp_proto_size = -1;
  44 static int hf_aarp_opcode = -1;
  45 static int hf_aarp_src_hw = -1;
  46 static int hf_aarp_src_hw_mac = -1;
  47 static int hf_aarp_src_proto = -1;
  48 static int hf_aarp_src_proto_id = -1;
  49 static int hf_aarp_dst_hw = -1;
  50 static int hf_aarp_dst_hw_mac = -1;
  51 static int hf_aarp_dst_proto = -1;
  52 static int hf_aarp_dst_proto_id = -1;
  53
  54 static gint ett_aarp = -1;
  55
  56 #ifndef AARP_REQUEST
  57 #define AARP_REQUEST    0x0001
  58 #endif
  59 #ifndef AARP_REPLY
  60 #define AARP_REPLY      0x0002
  61 #endif
  62 #ifndef AARP_PROBE
  63 #define AARP_PROBE      0x0003
  64 #endif
  65
  66 /* The following is screwed up shit to deal with the fact that
  67    the linux kernel edits the packet inline. */
  68 #define AARP_REQUEST_SWAPPED    0x0100
  69 #define AARP_REPLY_SWAPPED  0x0200
  70 #define AARP_PROBE_SWAPPED  0x0300
  71
  72 static const value_string op_vals[] = {
  73   {AARP_REQUEST,  "request" },
  74   {AARP_REPLY,    "reply"   },
  75   {AARP_PROBE,    "probe"   },
  76   {AARP_REQUEST_SWAPPED,  "request" },
  77   {AARP_REPLY_SWAPPED,    "reply"   },
  78   {AARP_PROBE_SWAPPED,    "probe"   },
  79   {0,             NULL           } };
  80
  81 /* AARP protocol HARDWARE identifiers. */
  82 #define AARPHRD_ETHER   1               /* Ethernet 10Mbps              */
  83 #define AARPHRD_TR      2               /* Token Ring                   */
  84
  85 static const value_string hrd_vals[] = {
  86   {AARPHRD_ETHER,   "Ethernet"       },
  87   {AARPHRD_TR,      "Token Ring"     },
  88   {0,               NULL             } };
  89
  90 /*
  91  * Given the hardware address type and length, check whether an address
  92  * is an Ethernet address - the address must be of type "Ethernet" or
  93  * "Token Ring", and the length must be 6 bytes.
  94  */
  95 #define AARP_HW_IS_ETHER(ar_hrd, ar_hln) \
  96         (((ar_hrd) == AARPHRD_ETHER || (ar_hrd) == AARPHRD_TR) \
  97                                 && (ar_hln) == 6)
  98
  99 /*
 100  * Given the protocol address type and length, check whether an address
 101  * is an Appletalk address - the address must be of type "Appletalk",
 102  * and the length must be 4 bytes.
 103  */
 104 #define AARP_PRO_IS_ATALK(ar_pro, ar_pln) \
 105         ((ar_pro) == ETHERTYPE_ATALK && (ar_pln) == 4)
 106
 107 static gchar *
 108 tvb_atalkid_to_str(tvbuff_t *tvb, gint offset)
 109 {
 110   gint node;
 111   gchar *cur;
 112
 113   cur=(gchar *)wmem_alloc(wmem_packet_scope(), 16);
 114   node=tvb_get_guint8(tvb, offset)<<8|tvb_get_guint8(tvb, offset+1);
 115   g_snprintf(cur, 16, "%d.%d",node,tvb_get_guint8(tvb, offset+2));
 116   return cur;
 117 }
 118
 119 static const gchar *
 120 tvb_aarphrdaddr_to_str(tvbuff_t *tvb, gint offset, int ad_len, guint16 type)
 121 {
 122   if (AARP_HW_IS_ETHER(type, ad_len)) {
 123     /* Ethernet address (or Token Ring address, which is the same type
 124        of address). */
 125     return tvb_ether_to_str(tvb, offset);
 126   }
 127   return tvb_bytes_to_str(tvb, offset, ad_len);
 128 }
 129
 130 static gchar *
 131 tvb_aarpproaddr_to_str(tvbuff_t *tvb, gint offset, int ad_len, guint16 type)
 132 {
 133   if (AARP_PRO_IS_ATALK(type, ad_len)) {
 134     /* Appletalk address.  */
 135     return tvb_atalkid_to_str(tvb, offset);
 136   }
 137   return tvb_bytes_to_str(tvb, offset, ad_len);
 138 }
 139
 140 /* Offsets of fields within an AARP packet. */
 141 #define AR_HRD          0
 142 #define AR_PRO          2
 143 #define AR_HLN          4
 144 #define AR_PLN          5
 145 #define AR_OP           6
 146 #define MIN_AARP_HEADER_SIZE    8
 147
 148 static void
 149 dissect_aarp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) {
 150   guint16     ar_hrd;
 151   guint16     ar_pro;
 152   guint8      ar_hln;
 153   guint8      ar_pln;
 154   guint16     ar_op;
 155   proto_tree  *aarp_tree;
 156   proto_item  *ti;
 157   const gchar *op_str;
 158   int         sha_offset, spa_offset, tha_offset, tpa_offset;
 159   const gchar *sha_str, *spa_str, /* *tha_str, */ *tpa_str;
 160
 161   col_set_str(pinfo->cinfo, COL_PROTOCOL, "AARP");
 162   col_clear(pinfo->cinfo, COL_INFO);
 163
 164   ar_hrd = tvb_get_ntohs(tvb, AR_HRD);
 165   ar_pro = tvb_get_ntohs(tvb, AR_PRO);
 166   ar_hln = tvb_get_guint8(tvb, AR_HLN);
 167   ar_pln = tvb_get_guint8(tvb, AR_PLN);
 168   ar_op  = tvb_get_ntohs(tvb, AR_OP);
 169
 170   /* Get the offsets of the addresses. */
 171   sha_offset = MIN_AARP_HEADER_SIZE;
 172   spa_offset = sha_offset + ar_hln;
 173   tha_offset = spa_offset + ar_pln;
 174   tpa_offset = tha_offset + ar_hln;
 175
 176   /* Extract the addresses.  */
 177   sha_str = tvb_aarphrdaddr_to_str(tvb, sha_offset, ar_hln, ar_hrd);
 178   spa_str = tvb_aarpproaddr_to_str(tvb, spa_offset, ar_pln, ar_pro);
 179 #if 0
 180   /* TODO: tha_str is currently not shown nor parsed */
 181   tha_str = tvb_aarphrdaddr_to_str(tvb, tha_offset, ar_hln, ar_hrd);
 182 #endif
 183   tpa_str = tvb_aarpproaddr_to_str(tvb, tpa_offset, ar_pln, ar_pro);
 184
 185   switch (ar_op) {
 186     case AARP_REQUEST:
 187     case AARP_REQUEST_SWAPPED:
 188       col_add_fstr(pinfo->cinfo, COL_INFO, "Who has %s?  Tell %s", tpa_str, spa_str);
 189       break;
 190     case AARP_REPLY:
 191     case AARP_REPLY_SWAPPED:
 192       col_add_fstr(pinfo->cinfo, COL_INFO, "%s is at %s", spa_str, sha_str);
 193       break;
 194     case AARP_PROBE:
 195     case AARP_PROBE_SWAPPED:
 196       col_add_fstr(pinfo->cinfo, COL_INFO, "Is there a %s", tpa_str);
 197       break;
 198     default:
 199       col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown AARP opcode 0x%04x", ar_op);
 200       break;
 201   }
 202
 203   if (tree) {
 204     if ((op_str = try_val_to_str(ar_op, op_vals)))
 205       ti = proto_tree_add_protocol_format(tree, proto_aarp, tvb, 0,
 206                                       MIN_AARP_HEADER_SIZE + 2*ar_hln +
 207                                       2*ar_pln, "AppleTalk Address Resolution Protocol (%s)", op_str);
 208     else
 209       ti = proto_tree_add_protocol_format(tree, proto_aarp, tvb, 0,
 210                                       MIN_AARP_HEADER_SIZE + 2*ar_hln +
 211                                       2*ar_pln,
 212                                       "AppleTalk Address Resolution Protocol (opcode 0x%04x)", ar_op);
 213     aarp_tree = proto_item_add_subtree(ti, ett_aarp);
 214     proto_tree_add_uint(aarp_tree, hf_aarp_hard_type, tvb, AR_HRD, 2,
 215                                ar_hrd);
 216     proto_tree_add_uint(aarp_tree, hf_aarp_proto_type, tvb, AR_PRO, 2,
 217                                ar_pro);
 218     proto_tree_add_uint(aarp_tree, hf_aarp_hard_size, tvb, AR_HLN, 1,
 219                                ar_hln);
 220     proto_tree_add_uint(aarp_tree, hf_aarp_proto_size, tvb, AR_PLN, 1,
 221                                ar_pln);
 222     proto_tree_add_uint(aarp_tree, hf_aarp_opcode, tvb, AR_OP, 2,
 223                                ar_op);
 224     if (ar_hln != 0) {
 225       proto_tree_add_item(aarp_tree,
 226         AARP_HW_IS_ETHER(ar_hrd, ar_hln) ? hf_aarp_src_hw_mac : hf_aarp_src_hw,
 227         tvb, sha_offset, ar_hln, ENC_NA);
 228     }
 229
 230     if (ar_pln != 0) {
 231       if (AARP_PRO_IS_ATALK(ar_pro, ar_pln)) {
 232         proto_tree_add_bytes_format_value(aarp_tree, hf_aarp_src_proto_id, tvb,
 233                                           spa_offset, ar_pln, NULL,
 234                                           "%s", spa_str);
 235       } else {
 236         proto_tree_add_bytes_format_value(aarp_tree, hf_aarp_src_proto, tvb,
 237                                           spa_offset, ar_pln, NULL,
 238                                           "%s", spa_str);
 239       }
 240     }
 241
 242     if (ar_hln != 0) {
 243       proto_tree_add_item(aarp_tree,
 244         AARP_HW_IS_ETHER(ar_hrd, ar_hln) ? hf_aarp_dst_hw_mac : hf_aarp_dst_hw,
 245         tvb, tha_offset, ar_hln, ENC_NA);
 246     }
 247
 248     if (ar_pln != 0) {
 249       if (AARP_PRO_IS_ATALK(ar_pro, ar_pln)) {
 250         proto_tree_add_bytes_format_value(aarp_tree, hf_aarp_dst_proto_id, tvb,
 251                                           tpa_offset, ar_pln,
 252                                           NULL, "%s", tpa_str);
 253       } else {
 254         proto_tree_add_bytes_format_value(aarp_tree, hf_aarp_dst_proto, tvb,
 255                                           tpa_offset, ar_pln,
 256                                           NULL, "%s", tpa_str);
 257       }
 258     }
 259   }
 260 }
 261
 262 void
 263 proto_register_aarp(void)
 264 {
 265   static hf_register_info hf[] = {
 266     { &hf_aarp_hard_type,
 267       { "Hardware type",                "aarp.hard.type",
 268         FT_UINT16,      BASE_HEX,       VALS(hrd_vals), 0x0,
 269         NULL, HFILL }},
 270
 271     { &hf_aarp_proto_type,
 272       { "Protocol type",                "aarp.proto.type",
 273         FT_UINT16,      BASE_HEX,       VALS(etype_vals),       0x0,
 274         NULL, HFILL }},
 275
 276     { &hf_aarp_hard_size,
 277       { "Hardware size",                "aarp.hard.size",
 278         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 279         NULL, HFILL }},
 280
 281     { &hf_aarp_proto_size,
 282       { "Protocol size",                "aarp.proto.size",
 283         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 284         NULL, HFILL }},
 285
 286     { &hf_aarp_opcode,
 287       { "Opcode",                       "aarp.opcode",
 288         FT_UINT16,      BASE_DEC,       VALS(op_vals),  0x0,
 289         NULL, HFILL }},
 290
 291     { &hf_aarp_src_hw,
 292       { "Sender hardware address",      "aarp.src.hw",
 293         FT_BYTES,       BASE_NONE,      NULL,   0x0,
 294         NULL, HFILL }},
 295
 296     { &hf_aarp_src_hw_mac,
 297       { "Sender MAC address",           "aarp.src.hw_mac",
 298         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 299         NULL, HFILL }},
 300
 301     { &hf_aarp_src_proto,
 302       { "Sender protocol address",      "aarp.src.proto",
 303         FT_BYTES,       BASE_NONE,      NULL,   0x0,
 304         NULL, HFILL }},
 305
 306     { &hf_aarp_src_proto_id,
 307       { "Sender ID",                    "aarp.src.proto_id",
 308         FT_BYTES,       BASE_NONE,      NULL,   0x0,
 309         NULL, HFILL }},
 310
 311     { &hf_aarp_dst_hw,
 312       { "Target hardware address",      "aarp.dst.hw",
 313         FT_BYTES,       BASE_NONE,      NULL,   0x0,
 314         NULL, HFILL }},
 315
 316     { &hf_aarp_dst_hw_mac,
 317       { "Target MAC address",           "aarp.dst.hw_mac",
 318         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 319         NULL, HFILL }},
 320
 321     { &hf_aarp_dst_proto,
 322       { "Target protocol address",      "aarp.dst.proto",
 323         FT_BYTES,       BASE_NONE,      NULL,   0x0,
 324       NULL, HFILL }},
 325
 326     { &hf_aarp_dst_proto_id,
 327       { "Target ID",                    "aarp.dst.proto_id",
 328         FT_BYTES,       BASE_NONE,      NULL,   0x0,
 329         NULL, HFILL }},
 330   };
 331   static gint *ett[] = {
 332     &ett_aarp,
 333   };
 334
 335   proto_aarp = proto_register_protocol("Appletalk Address Resolution Protocol",
 336                                        "AARP",
 337                                        "aarp");
 338   proto_register_field_array(proto_aarp, hf, array_length(hf));
 339   proto_register_subtree_array(ett, array_length(ett));
 340 }
 341
 342 void
 343 proto_reg_handoff_aarp(void)
 344 {
 345   dissector_handle_t aarp_handle;
 346
 347   aarp_handle = create_dissector_handle(dissect_aarp, proto_aarp);
 348   dissector_add_uint("ethertype", ETHERTYPE_AARP, aarp_handle);
 349   dissector_add_uint("chdlc.protocol", ETHERTYPE_AARP, aarp_handle);
 350 }