packet-hsrp.c

   1 /* packet-hsrp.c
   2  * Routines for the Cisco Hot Standby Router Protocol (HSRP)
   3  * RFC 2281
   4  *
   5  * Heikki Vatiainen <hessu@cs.tut.fi>
   6  *
   7  * $Id: packet-hsrp.c,v 1.24 2002/08/28 21:00:16 jmayer Exp $
   8  *
   9  * Ethereal - Network traffic analyzer
  10  * By Gerald Combs <gerald@ethereal.com>
  11  * Copyright 1998 Gerald Combs
  12  *
  13  * Copied from packet-vrrp.c
  14  *
  15  * This program is free software; you can redistribute it and/or
  16  * modify it under the terms of the GNU General Public License
  17  * as published by the Free Software Foundation; either version 2
  18  * of the License, or (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software
  27  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  28  */
  29
  30 #ifdef HAVE_CONFIG_H
  31 # include "config.h"
  32 #endif
  33
  34 #include <string.h>
  35 #include <glib.h>
  36 #include <epan/packet.h>
  37
  38 static gint proto_hsrp = -1;
  39
  40 static gint hf_hsrp_version = -1;
  41 static gint hf_hsrp_opcode = -1;
  42 static gint hf_hsrp_state = -1;
  43 static gint hf_hsrp_hellotime = -1;
  44 static gint hf_hsrp_holdtime = -1;
  45 static gint hf_hsrp_priority = -1;
  46 static gint hf_hsrp_group = -1;
  47 static gint hf_hsrp_reserved = -1;
  48 static gint hf_hsrp_auth_data = -1;
  49 static gint hf_hsrp_virt_ip_addr = -1;
  50
  51 static gint ett_hsrp = -1;
  52
  53 #define UDP_PORT_HSRP   1985
  54
  55 struct hsrp_packet {          /* Multicast to 224.0.0.2, TTL 1, UDP, port 1985 */
  56         guint8  version;      /* RFC2281 describes version 0 */
  57         guint8  opcode;
  58         guint8  state;
  59 #define HSRP_DEFAULT_HELLOTIME 3
  60         guint8  hellotime;    /* In seconds */
  61 #define HSRP_DEFAULT_HOLDTIME 10
  62         guint8  holdtime;     /* In seconds */
  63         guint8  priority;     /* Higher is stronger, highest IP address tie-breaker */
  64         guint8  group;        /* Identifies the standby group */
  65         guint8  reserved;
  66         guint8  auth_data[8]; /* Clear-text password, recommended default is `cisco' */
  67         guint32 virt_ip_addr; /* The virtual IP address used by this group */
  68 };
  69
  70
  71 #define HSRP_OPCODE_HELLO  0
  72 #define HSRP_OPCODE_COUP   1
  73 #define HSRP_OPCODE_RESIGN 2
  74 static const value_string hsrp_opcode_vals[] = {
  75         {HSRP_OPCODE_HELLO,  "Hello"},
  76         {HSRP_OPCODE_COUP,   "Coup"},
  77         {HSRP_OPCODE_RESIGN, "Resign"},
  78         {0, NULL},
  79 };
  80
  81 #define HSRP_STATE_INITIAL  0
  82 #define HSRP_STATE_LEARN    1
  83 #define HSRP_STATE_LISTEN   2
  84 #define HSRP_STATE_SPEAK    4
  85 #define HSRP_STATE_STANDBY  8
  86 #define HSRP_STATE_ACTIVE  16
  87 static const value_string hsrp_state_vals[] = {
  88         {HSRP_STATE_INITIAL, "Initial"},
  89         {HSRP_STATE_LEARN,   "Learn"},
  90         {HSRP_STATE_LISTEN,  "Listen"},
  91         {HSRP_STATE_SPEAK,   "Speak"},
  92         {HSRP_STATE_STANDBY, "Standby"},
  93         {HSRP_STATE_ACTIVE,  "Active"},
  94         {0, NULL},
  95 };
  96
  97 static void
  98 dissect_hsrp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  99 {
 100         guint8 opcode, state;
 101
 102         if (check_col(pinfo->cinfo, COL_PROTOCOL))
 103                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "HSRP");
 104         if (check_col(pinfo->cinfo, COL_INFO))
 105                 col_clear(pinfo->cinfo, COL_INFO);
 106
 107         opcode = tvb_get_guint8(tvb, 1);
 108         state = tvb_get_guint8(tvb, 2);
 109         if (check_col(pinfo->cinfo, COL_INFO)) {
 110                 col_add_fstr(pinfo->cinfo, COL_INFO, "%s (state %s)",
 111                              val_to_str(opcode, hsrp_opcode_vals, "Unknown"),
 112                              val_to_str(state, hsrp_state_vals, "Unknown"));
 113         }
 114
 115         if (tree) {
 116                 proto_item *ti;
 117                 proto_tree *hsrp_tree;
 118                 int offset;
 119                 guint8 hellotime, holdtime;
 120                 guint8 auth_buf[8 + 1];
 121
 122                 offset = 0;
 123                 ti = proto_tree_add_item(tree, proto_hsrp, tvb, offset, -1, FALSE);
 124                 hsrp_tree = proto_item_add_subtree(ti, ett_hsrp);
 125
 126                 proto_tree_add_item(hsrp_tree, hf_hsrp_version, tvb, offset, 1, FALSE);
 127                 offset++;
 128                 proto_tree_add_uint(hsrp_tree, hf_hsrp_opcode, tvb, offset, 1, opcode);
 129                 offset++;
 130                 proto_tree_add_uint(hsrp_tree, hf_hsrp_state, tvb, offset, 1, state);
 131                 offset++;
 132                 hellotime = tvb_get_guint8(tvb, offset);
 133                 proto_tree_add_uint_format(hsrp_tree, hf_hsrp_hellotime, tvb, offset, 1, hellotime,
 134                                            "Hellotime: %sDefault (%u)",
 135                                            (hellotime == HSRP_DEFAULT_HELLOTIME) ? "" : "Non-",
 136                                            hellotime);
 137                 offset++;
 138                 holdtime = tvb_get_guint8(tvb, offset);
 139                 proto_tree_add_uint_format(hsrp_tree, hf_hsrp_holdtime, tvb, offset, 1, holdtime,
 140                                            "Holdtime: %sDefault (%u)",
 141                                            (holdtime == HSRP_DEFAULT_HOLDTIME) ? "" : "Non-",
 142                                            holdtime);
 143                 offset++;
 144                 proto_tree_add_item(hsrp_tree, hf_hsrp_priority, tvb, offset, 1, FALSE);
 145                 offset++;
 146                 proto_tree_add_item(hsrp_tree, hf_hsrp_group, tvb, offset, 1, FALSE);
 147                 offset++;
 148                 proto_tree_add_item(hsrp_tree, hf_hsrp_reserved, tvb, offset, 1, FALSE);
 149                 offset++;
 150                 tvb_memcpy(tvb, auth_buf, offset, 8);
 151                 auth_buf[sizeof auth_buf - 1] = '\0';
 152                 proto_tree_add_string_format(hsrp_tree, hf_hsrp_auth_data, tvb, offset, 8, auth_buf,
 153                                              "Authentication Data: %sDefault (%s)",
 154                                              (tvb_strneql(tvb, offset, "cisco", strlen("cisco"))) == 0 ? "" : "Non-",
 155                                              auth_buf);
 156                 offset += 8;
 157                 proto_tree_add_item(hsrp_tree, hf_hsrp_virt_ip_addr, tvb, offset, 4, FALSE);
 158                 offset += 4;
 159
 160         }
 161
 162         return;
 163 }
 164
 165 void proto_register_hsrp(void)
 166 {
 167         static hf_register_info hf[] = {
 168                 { &hf_hsrp_version,
 169                   { "Version", "hsrp.version",
 170                     FT_UINT8, BASE_DEC, NULL, 0x0,
 171                     "The version of the HSRP messages", HFILL }},
 172
 173                 { &hf_hsrp_opcode,
 174                   { "Op Code", "hsrp.opcode",
 175                     FT_UINT8, BASE_DEC, VALS(hsrp_opcode_vals), 0x0,
 176                     "The type of message contained in this packet", HFILL }},
 177
 178                 { &hf_hsrp_state,
 179                   { "State", "hsrp.state",
 180                     FT_UINT8, BASE_DEC, VALS(hsrp_state_vals), 0x0,
 181                     "The current state of the router sending the message", HFILL }},
 182
 183                 { &hf_hsrp_hellotime,
 184                   { "Hellotime", "hsrp.hellotime",
 185                     FT_UINT8, BASE_DEC, NULL, 0x0,
 186                     "The approximate period between the Hello messages that the router sends", HFILL }},
 187
 188                 { &hf_hsrp_holdtime,
 189                   { "Holdtime", "hsrp.holdtime",
 190                     FT_UINT8, BASE_DEC, NULL, 0x0,
 191                     "Time that the current Hello message should be considered valid", HFILL }},
 192
 193                 { &hf_hsrp_priority,
 194                   { "Priority", "hsrp.priority",
 195                     FT_UINT8, BASE_DEC, NULL, 0x0,
 196                     "Used to elect the active and standby routers. Numerically higher priority wins vote", HFILL }},
 197
 198                 { &hf_hsrp_group,
 199                   { "Group", "hsrp.group",
 200                     FT_UINT8, BASE_DEC, NULL, 0x0,
 201                     "This field identifies the standby group", HFILL }},
 202
 203                 { &hf_hsrp_reserved,
 204                   { "Reserved", "hsrp.reserved",
 205                     FT_UINT8, BASE_DEC, NULL, 0x0,
 206                     "Reserved", HFILL }},
 207
 208                 { &hf_hsrp_auth_data,
 209                   { "Authentication Data", "hsrp.auth_data",
 210                     FT_STRING, 0, NULL, 0x0,
 211                     "Contains a clear-text 8 character reused password", HFILL }},
 212
 213                 { &hf_hsrp_virt_ip_addr,
 214                   { "Virtual IP Address", "hsrp.virt_ip",
 215                     FT_IPv4, 0, NULL, 0x0,
 216                     "The virtual IP address used by this group", HFILL }},
 217
 218         };
 219
 220         static gint *ett[] = {
 221                 &ett_hsrp,
 222         };
 223
 224         proto_hsrp = proto_register_protocol("Cisco Hot Standby Router Protocol",
 225             "HSRP", "hsrp");
 226         proto_register_field_array(proto_hsrp, hf, array_length(hf));
 227         proto_register_subtree_array(ett, array_length(ett));
 228
 229         return;
 230 }
 231
 232 void
 233 proto_reg_handoff_hsrp(void)
 234 {
 235         dissector_handle_t hsrp_handle;
 236
 237         hsrp_handle = create_dissector_handle(dissect_hsrp, proto_hsrp);
 238         dissector_add("udp.port", UDP_PORT_HSRP, hsrp_handle);
 239 }