epan/dissectors/packet-carp.c

   1 /* packet-carp.c
   2  * Routines for the Common Address Redundancy Protocol (CARP)
   3  * Copyright 2013, Uli Heilmeier <uh@heilmeier.eu>
   4  * Based on packet-vrrp.c by Heikki Vatiainen <hessu@cs.tut.fi>
   5  *
   6  * $Id$
   7  *
   8  * Wireshark - Network traffic analyzer
   9  * By Gerald Combs <gerald@wireshark.org>
  10  * Copyright 1998 Gerald Combs
  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 <glib.h>
  30 #include <epan/packet.h>
  31 #include <epan/ipproto.h>
  32 #include <epan/in_cksum.h>
  33
  34 static gint proto_carp = -1;
  35 static gint ett_carp = -1;
  36 static gint ett_carp_ver_type = -1;
  37
  38 static gint hf_carp_ver_type = -1;
  39 static gint hf_carp_version = -1;
  40 static gint hf_carp_type = -1;
  41 static gint hf_carp_vhid = -1;
  42 static gint hf_carp_advskew = -1;
  43 static gint hf_carp_authlen = -1;
  44 static gint hf_carp_demotion = -1;
  45 static gint hf_carp_advbase = -1;
  46 static gint hf_carp_counter = -1;
  47 static gint hf_carp_hmac = -1;
  48
  49 #define CARP_VERSION_MASK 0xf0
  50 #define CARP_TYPE_MASK 0x0f
  51
  52 #define CARP_TYPE_ADVERTISEMENT 1
  53 static const value_string carp_type_vals[] = {
  54     {CARP_TYPE_ADVERTISEMENT, "Advertisement"},
  55     {0, NULL}
  56 };
  57
  58 static gboolean
  59 test_carp_packet(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree _U_, void *data _U_)
  60 {
  61     guint8 ver_type, version, auth_length;
  62
  63     /* First some simple check if the data is
  64        really CARP */
  65     if (tvb_length(tvb) < 36)
  66         return FALSE;
  67
  68     /* Version must be 1 or 2, type must be in carp_type_vals */
  69     ver_type = tvb_get_guint8(tvb, 0);
  70     version = hi_nibble(ver_type);
  71     if ((version == 0) || (version > 2) ||
  72         (try_val_to_str(lo_nibble(ver_type), carp_type_vals) == NULL))
  73         return FALSE;
  74
  75     auth_length = tvb_get_guint8(tvb, 3);
  76     if ( auth_length != 7 )
  77         return FALSE;
  78
  79     return TRUE;
  80 }
  81
  82 static int
  83 dissect_carp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
  84 {
  85     int offset = 0;
  86     gint carp_len;
  87     guint8  vhid;
  88     vec_t cksum_vec[4];
  89     proto_item *ti, *tv;
  90     proto_tree *carp_tree, *ver_type_tree;
  91     guint8 ver_type;
  92     guint16 cksum, computed_cksum;
  93
  94     /* Make sure it's a CARP packet */
  95     if (!test_carp_packet(tvb, pinfo, tree, data))
  96         return 0;
  97
  98     col_set_str(pinfo->cinfo, COL_PROTOCOL, "CARP");
  99     col_clear(pinfo->cinfo, COL_INFO);
 100
 101     vhid = tvb_get_guint8(tvb, 1);
 102     col_add_fstr(pinfo->cinfo, COL_INFO, "%s (Virtual Host ID: %u)",
 103                  "Announcement", vhid);
 104
 105     ti = proto_tree_add_item(tree, proto_carp, tvb, 0, -1, ENC_NA);
 106     carp_tree = proto_item_add_subtree(ti, ett_carp);
 107
 108     ver_type = tvb_get_guint8(tvb, 0);
 109     tv = proto_tree_add_uint_format(carp_tree, hf_carp_ver_type,
 110                     tvb, offset, 1, ver_type,
 111                     "Version %u, Packet type %u (%s)",
 112                     hi_nibble(ver_type), lo_nibble(ver_type),
 113                     val_to_str_const(lo_nibble(ver_type), carp_type_vals, "Unknown"));
 114     ver_type_tree = proto_item_add_subtree(tv, ett_carp_ver_type);
 115     proto_tree_add_uint(ver_type_tree, hf_carp_version, tvb, offset, 1, ver_type);
 116     proto_tree_add_uint(ver_type_tree, hf_carp_type, tvb, offset, 1, ver_type);
 117     offset++;
 118
 119     proto_tree_add_item(carp_tree, hf_carp_vhid, tvb, offset, 1, ENC_BIG_ENDIAN);
 120     offset++;
 121
 122     proto_tree_add_item(carp_tree, hf_carp_advskew, tvb, offset, 1, ENC_BIG_ENDIAN);
 123     offset++;
 124
 125     proto_tree_add_item(carp_tree, hf_carp_authlen, tvb,
 126         offset, 1, ENC_NA);
 127     offset++;
 128
 129     proto_tree_add_item(carp_tree, hf_carp_demotion, tvb, offset, 1, ENC_BIG_ENDIAN);
 130     offset++;
 131
 132     proto_tree_add_item(carp_tree, hf_carp_advbase, tvb, offset, 1, ENC_BIG_ENDIAN);
 133     offset++;
 134
 135     cksum = tvb_get_ntohs(tvb, offset);
 136     carp_len = (gint)tvb_reported_length(tvb);
 137     if (!pinfo->fragmented && (gint)tvb_length(tvb) >= carp_len) {
 138         /* The packet isn't part of a fragmented datagram
 139            and isn't truncated, so we can checksum it. */
 140         cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, carp_len);
 141         cksum_vec[0].len = carp_len;
 142         computed_cksum = in_cksum(&cksum_vec[0], 1);
 143         if (computed_cksum == 0) {
 144             proto_tree_add_text(carp_tree, tvb, offset, 2,
 145                         "Checksum: 0x%04x [correct]",
 146                         cksum);
 147         } else {
 148             proto_tree_add_text(carp_tree, tvb, offset, 2,
 149                         "Checksum: 0x%04x [incorrect, should be 0x%04x]",
 150                         cksum,
 151                         in_cksum_shouldbe(cksum, computed_cksum));
 152         }
 153     } else {
 154         proto_tree_add_text(carp_tree, tvb, offset, 2,
 155                     "Checksum: 0x%04x", cksum);
 156     }
 157     offset+=2;
 158
 159     /* Counter */
 160     proto_tree_add_item(carp_tree, hf_carp_counter, tvb, offset, 8, ENC_BIG_ENDIAN);
 161     offset+=8;
 162
 163     proto_tree_add_item(carp_tree, hf_carp_hmac, tvb, offset, 20, ENC_ASCII|ENC_NA);
 164     offset+=20;
 165
 166     return offset;
 167 }
 168
 169 /* heuristic dissector */
 170 static gboolean
 171 dissect_carp_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
 172 {
 173     if (!test_carp_packet(tvb, pinfo, tree, data))
 174         return FALSE;
 175
 176     dissect_carp(tvb, pinfo, tree, data);
 177     return TRUE;
 178 }
 179
 180 void proto_register_carp(void)
 181 {
 182     static hf_register_info hf[] = {
 183         { &hf_carp_ver_type,
 184           {"CARP message version and type", "carp.typever",
 185            FT_UINT8, BASE_DEC, NULL, 0x0,
 186            "CARP version and type", HFILL }},
 187
 188         { &hf_carp_version,
 189           {"CARP protocol version", "carp.version",
 190            FT_UINT8, BASE_DEC, NULL, CARP_VERSION_MASK,
 191            "CARP version", HFILL }},
 192
 193         { &hf_carp_type,
 194           {"CARP packet type", "carp.type",
 195            FT_UINT8, BASE_DEC, VALS(carp_type_vals), CARP_TYPE_MASK,
 196            "CARP type", HFILL }},
 197
 198         { &hf_carp_vhid,
 199           {"Virtual Host ID", "carp.vhid",
 200            FT_UINT8, BASE_DEC, NULL, 0x0,
 201            NULL, HFILL }},
 202
 203         { &hf_carp_advskew,
 204           {"Advertisment Skew", "carp.advskew",
 205            FT_UINT8, BASE_DEC, NULL, 0x0,
 206            NULL, HFILL }},
 207
 208         { &hf_carp_authlen,
 209           {"Auth Len", "carp.authlen",
 210            FT_UINT8, BASE_DEC, NULL, 0x0,
 211            "Size of counter+hash in 32bit chunks", HFILL }},
 212
 213         { &hf_carp_demotion,
 214           {"Demotion indicator", "carp.demotion",
 215            FT_UINT8, BASE_DEC, NULL, 0x0,
 216            NULL, HFILL }},
 217
 218         { &hf_carp_advbase,
 219           {"Adver Int", "carp.adver_int",
 220            FT_UINT8, BASE_DEC, NULL, 0x0,
 221            "Time interval (in seconds) between ADVERTISEMENTS", HFILL }},
 222
 223         { &hf_carp_counter, {"Counter", "carp.counter",
 224            FT_UINT64, BASE_DEC, NULL, 0x0,
 225            NULL, HFILL }},
 226
 227         { &hf_carp_hmac,
 228           {"HMAC", "carp.hmac",
 229            FT_BYTES, BASE_NONE, NULL, 0x0,
 230            "SHA-1 HMAC", HFILL }},
 231     };
 232
 233     static gint *ett[] = {
 234         &ett_carp,
 235         &ett_carp_ver_type
 236     };
 237
 238     proto_carp = proto_register_protocol("Common Address Redundancy Protocol",
 239         "CARP", "carp");
 240     proto_register_field_array(proto_carp, hf, array_length(hf));
 241     proto_register_subtree_array(ett, array_length(ett));
 242 }
 243
 244 void
 245 proto_reg_handoff_carp(void)
 246 {
 247     dissector_handle_t carp_handle;
 248
 249     carp_handle = new_create_dissector_handle(dissect_carp, proto_carp);
 250     dissector_add_uint("ip.proto", IP_PROTO_VRRP, carp_handle);
 251     heur_dissector_add( "ip", dissect_carp_heur, proto_carp);
 252 }
 253
 254 /*
 255  * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 256  *
 257  * Local variables:
 258  * c-basic-offset: 4
 259  * tab-width: 8
 260  * indent-tabs-mode: nil
 261  * End:
 262  *
 263  * vi: set shiftwidth=4 tabstop=8 expandtab:
 264  * :indentSize=4:tabSize=8:noTabs=true:
 265  */