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  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  */
  12
  13 #include "config.h"
  14
  15 #include <epan/packet.h>
  16 #include <epan/ipproto.h>
  17 #include <epan/expert.h>
  18 #include <epan/in_cksum.h>
  19
  20 void proto_register_carp(void);
  21 void proto_reg_handoff_carp(void);
  22
  23 static dissector_handle_t carp_handle;
  24
  25 static int proto_carp;
  26 static int ett_carp;
  27 static int ett_carp_ver_type;
  28
  29 static int hf_carp_ver_type;
  30 static int hf_carp_version;
  31 static int hf_carp_type;
  32 static int hf_carp_vhid;
  33 static int hf_carp_advskew;
  34 static int hf_carp_authlen;
  35 static int hf_carp_demotion;
  36 static int hf_carp_advbase;
  37 static int hf_carp_counter;
  38 static int hf_carp_hmac;
  39 static int hf_carp_checksum;
  40 static int hf_carp_checksum_status;
  41
  42 static expert_field ei_carp_checksum;
  43
  44 #define CARP_VERSION_MASK 0xf0
  45 #define CARP_TYPE_MASK 0x0f
  46
  47 #define CARP_TYPE_ADVERTISEMENT 1
  48 static const value_string carp_type_vals[] = {
  49     {CARP_TYPE_ADVERTISEMENT, "Advertisement"},
  50     {0, NULL}
  51 };
  52
  53 static bool
  54 test_carp_packet(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree _U_, void *data _U_)
  55 {
  56     uint8_t ver_type, version, auth_length;
  57
  58     /* First some simple check if the data is
  59        really CARP */
  60     if (tvb_captured_length(tvb) < 36)
  61         return false;
  62
  63     /* Version must be 1 or 2, type must be in carp_type_vals */
  64     ver_type = tvb_get_uint8(tvb, 0);
  65     version = hi_nibble(ver_type);
  66     if ((version == 0) || (version > 2) ||
  67         (try_val_to_str(lo_nibble(ver_type), carp_type_vals) == NULL))
  68         return false;
  69
  70     auth_length = tvb_get_uint8(tvb, 3);
  71     if ( auth_length != 7 )
  72         return false;
  73
  74     return true;
  75 }
  76
  77 static int
  78 dissect_carp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
  79 {
  80     int offset = 0;
  81     unsigned carp_len;
  82     uint8_t vhid;
  83     vec_t cksum_vec[4];
  84     proto_item *ti, *tv;
  85     proto_tree *carp_tree, *ver_type_tree;
  86     uint8_t ver_type;
  87
  88     /* Make sure it's a CARP packet */
  89     if (!test_carp_packet(tvb, pinfo, tree, data))
  90         return 0;
  91
  92     col_set_str(pinfo->cinfo, COL_PROTOCOL, "CARP");
  93     col_clear(pinfo->cinfo, COL_INFO);
  94
  95     vhid = tvb_get_uint8(tvb, 1);
  96     col_add_fstr(pinfo->cinfo, COL_INFO, "%s (Virtual Host ID: %u)",
  97                  "Announcement", vhid);
  98
  99     ti = proto_tree_add_item(tree, proto_carp, tvb, 0, -1, ENC_NA);
 100     carp_tree = proto_item_add_subtree(ti, ett_carp);
 101
 102     ver_type = tvb_get_uint8(tvb, 0);
 103     tv = proto_tree_add_uint_format(carp_tree, hf_carp_ver_type,
 104                     tvb, offset, 1, ver_type,
 105                     "Version %u, Packet type %u (%s)",
 106                     hi_nibble(ver_type), lo_nibble(ver_type),
 107                     val_to_str_const(lo_nibble(ver_type), carp_type_vals, "Unknown"));
 108     ver_type_tree = proto_item_add_subtree(tv, ett_carp_ver_type);
 109     proto_tree_add_uint(ver_type_tree, hf_carp_version, tvb, offset, 1, ver_type);
 110     proto_tree_add_uint(ver_type_tree, hf_carp_type, tvb, offset, 1, ver_type);
 111     offset++;
 112
 113     proto_tree_add_item(carp_tree, hf_carp_vhid, tvb, offset, 1, ENC_BIG_ENDIAN);
 114     offset++;
 115
 116     proto_tree_add_item(carp_tree, hf_carp_advskew, tvb, offset, 1, ENC_BIG_ENDIAN);
 117     offset++;
 118
 119     proto_tree_add_item(carp_tree, hf_carp_authlen, tvb,
 120         offset, 1, ENC_BIG_ENDIAN);
 121     offset++;
 122
 123     proto_tree_add_item(carp_tree, hf_carp_demotion, tvb, offset, 1, ENC_BIG_ENDIAN);
 124     offset++;
 125
 126     proto_tree_add_item(carp_tree, hf_carp_advbase, tvb, offset, 1, ENC_BIG_ENDIAN);
 127     offset++;
 128
 129     carp_len = tvb_reported_length(tvb);
 130     if (!pinfo->fragmented && tvb_captured_length(tvb) >= carp_len) {
 131         /* The packet isn't part of a fragmented datagram
 132            and isn't truncated, so we can checksum it. */
 133         SET_CKSUM_VEC_TVB(cksum_vec[0], tvb, 0, carp_len);
 134         proto_tree_add_checksum(carp_tree, tvb, offset, hf_carp_checksum, hf_carp_checksum_status, &ei_carp_checksum, pinfo, in_cksum(&cksum_vec[0], 1),
 135                                 ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);
 136     } else {
 137         proto_tree_add_checksum(carp_tree, tvb, offset, hf_carp_checksum, hf_carp_checksum_status, &ei_carp_checksum, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
 138     }
 139
 140     offset+=2;
 141
 142     /* Counter */
 143     proto_tree_add_item(carp_tree, hf_carp_counter, tvb, offset, 8, ENC_BIG_ENDIAN);
 144     offset+=8;
 145
 146     proto_tree_add_item(carp_tree, hf_carp_hmac, tvb, offset, 20, ENC_NA);
 147     offset+=20;
 148
 149     return offset;
 150 }
 151
 152 /* heuristic dissector */
 153 static bool
 154 dissect_carp_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
 155 {
 156     if (!test_carp_packet(tvb, pinfo, tree, data))
 157         return false;
 158
 159     dissect_carp(tvb, pinfo, tree, data);
 160     return true;
 161 }
 162
 163 void proto_register_carp(void)
 164 {
 165     static hf_register_info hf[] = {
 166         { &hf_carp_ver_type,
 167           {"CARP message version and type", "carp.typever",
 168            FT_UINT8, BASE_DEC, NULL, 0x0,
 169            NULL, HFILL }},
 170
 171         { &hf_carp_version,
 172           {"CARP protocol version", "carp.version",
 173            FT_UINT8, BASE_DEC, NULL, CARP_VERSION_MASK,
 174            NULL, HFILL }},
 175
 176         { &hf_carp_type,
 177           {"CARP packet type", "carp.type",
 178            FT_UINT8, BASE_DEC, VALS(carp_type_vals), CARP_TYPE_MASK,
 179            NULL, HFILL }},
 180
 181         { &hf_carp_vhid,
 182           {"Virtual Host ID", "carp.vhid",
 183            FT_UINT8, BASE_DEC, NULL, 0x0,
 184            NULL, HFILL }},
 185
 186         { &hf_carp_advskew,
 187           {"Advertisement Skew", "carp.advskew",
 188            FT_UINT8, BASE_DEC, NULL, 0x0,
 189            NULL, HFILL }},
 190
 191         { &hf_carp_authlen,
 192           {"Auth Len", "carp.authlen",
 193            FT_UINT8, BASE_DEC, NULL, 0x0,
 194            "Size of counter+hash in 32bit chunks", HFILL }},
 195
 196         { &hf_carp_demotion,
 197           {"Demotion indicator", "carp.demotion",
 198            FT_UINT8, BASE_DEC, NULL, 0x0,
 199            NULL, HFILL }},
 200
 201         { &hf_carp_advbase,
 202           {"Adver Int", "carp.adver_int",
 203            FT_UINT8, BASE_DEC, NULL, 0x0,
 204            "Time interval (in seconds) between ADVERTISEMENTS", HFILL }},
 205
 206         { &hf_carp_counter, {"Counter", "carp.counter",
 207            FT_UINT64, BASE_DEC, NULL, 0x0,
 208            NULL, HFILL }},
 209
 210         { &hf_carp_hmac,
 211           {"HMAC", "carp.hmac",
 212            FT_BYTES, BASE_NONE, NULL, 0x0,
 213            "SHA-1 HMAC", HFILL }},
 214
 215         { &hf_carp_checksum,
 216           {"Checksum", "carp.checksum",
 217            FT_UINT16, BASE_HEX, NULL, 0x0,
 218            NULL, HFILL }},
 219
 220         { &hf_carp_checksum_status,
 221           {"Checksum Status", "carp.checksum.status",
 222            FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,
 223            NULL, HFILL }},
 224     };
 225
 226     static int *ett[] = {
 227         &ett_carp,
 228         &ett_carp_ver_type
 229     };
 230
 231     static ei_register_info ei[] = {
 232         { &ei_carp_checksum, { "carp.bad_checksum", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }},
 233     };
 234
 235     expert_module_t* expert_carp;
 236
 237     proto_carp = proto_register_protocol("Common Address Redundancy Protocol", "CARP", "carp");
 238     carp_handle = register_dissector("carp", dissect_carp, proto_carp);
 239     proto_register_field_array(proto_carp, hf, array_length(hf));
 240     proto_register_subtree_array(ett, array_length(ett));
 241     expert_carp = expert_register_protocol(proto_carp);
 242     expert_register_field_array(expert_carp, ei, array_length(ei));
 243 }
 244
 245 void
 246 proto_reg_handoff_carp(void)
 247 {
 248     dissector_add_uint("ip.proto", IP_PROTO_VRRP, carp_handle);
 249     heur_dissector_add( "ip", dissect_carp_heur, "CARP over IP", "carp_ip", proto_carp, HEURISTIC_ENABLE);
 250 }
 251
 252 /*
 253  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 254  *
 255  * Local variables:
 256  * c-basic-offset: 4
 257  * tab-width: 8
 258  * indent-tabs-mode: nil
 259  * End:
 260  *
 261  * vi: set shiftwidth=4 tabstop=8 expandtab:
 262  * :indentSize=4:tabSize=8:noTabs=true:
 263  */