epan/dissectors/packet-vssmonitoring.c

   1 /* packet-vssmonitoring.c
   2  * Routines for dissection of VSS-monitoring timestamp and portstamp
   3  *
   4  * Copyright VSS-Monitoring 2011
   5  *
   6  * 20111205 - First edition by Sake Blok (sake.blok@SYN-bit.nl)
   7  *
   8  * $Id$
   9  *
  10  * Wireshark - Network traffic analyzer
  11  * By Gerald Combs <gerald@wireshark.org>
  12  * Copyright 1998 Gerald Combs
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License
  16  * as published by the Free Software Foundation; either version 2
  17  * of the License, or (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, write to the Free Software
  26  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  27  */
  28
  29 #include "config.h"
  30
  31 #include <epan/packet.h>
  32 #include <epan/prefs.h>
  33
  34
  35 #define VSS_NS_MASK     0x3fffffff
  36 #define CLKSRC_SHIFT    30
  37
  38 #define CLKSRC_LOCAL    0
  39 #define CLKSRC_NTP      1
  40 #define CLKSRC_GPS      2
  41 #define CLKSRC_PTP      3
  42
  43 static const value_string clksrc_vals[] = {
  44   { CLKSRC_LOCAL,       "Not Synced" },
  45   { CLKSRC_NTP,         "NTP" },
  46   { CLKSRC_GPS,         "GPS" },
  47   { CLKSRC_PTP,         "PTP" },
  48   { 0,                  NULL }
  49 };
  50
  51
  52 static int proto_vssmonitoring = -1;
  53
  54 static int hf_vssmonitoring_time = -1;
  55 static int hf_vssmonitoring_clksrc = -1;
  56 static int hf_vssmonitoring_srcport = -1;
  57
  58 static gint ett_vssmonitoring = -1;
  59
  60 static gboolean vssmonitoring_use_heuristics = TRUE;
  61
  62 static int
  63 dissect_vssmonitoring(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
  64 {
  65   proto_tree    *ti = NULL;
  66   proto_tree    *vssmonitoring_tree = NULL;
  67   guint         offset = 0;
  68
  69   guint         trailer_len;
  70   nstime_t      vssmonitoring_time;
  71   guint8        vssmonitoring_clksrc = 0;
  72   guint16       vssmonitoring_srcport = 0;
  73
  74   struct tm     *tmp;
  75
  76
  77   /* First get the length of the trailer */
  78   trailer_len = tvb_reported_length(tvb);
  79
  80   /* The trailer length is a sum (of any combination) of:
  81    * timestamp (8 bytes)
  82    * port stamp (1 or 2 bytes)
  83    * fcs (4 bytes)
  84    *
  85    * The FCS is dissected by our caller, so we check for a trailer
  86    * with a length that includes one or more of a time stamp and
  87    * a 1-byte or 2-byte port stamp.
  88    *
  89    * See
  90    *
  91    *    http://www.vssmonitoring.com/portals/application_note/Port%20and%20Time%20Stamping.pdf
  92    *
  93    * (although that speaks of 2-byte port stamps as being for a "future
  94    * release").
  95    *
  96    * This means a trailer length must not be more than 14 bytes,
  97    * and:
  98    *
  99    *    must not be 3 modulo 3 (as it can't have both a 1-byte
 100    *    and a 2-byte port stamp);
 101    *
 102    *    if it's less than 8 bytes, must not be 0 modulo 3 (as
 103    *    it must have a 1-byte or 2-byte port stamp, given that
 104    *    it has no timestamp).
 105    */
 106   if ( trailer_len > 14 )
 107     return 0;
 108
 109   /* ... and also a 1-byte port stamp can not co-exist with a 2-byte
 110    * portstamp
 111    */
 112   if ( (trailer_len & 3) == 3 )
 113     return 0;
 114
 115   /* ... and if you have neither a time stamp nor a port stamp,
 116    * you don't have a trailer
 117    */
 118   if ( (trailer_len & 3) == 0 && trailer_len < 8 )
 119     return 0;
 120
 121   if ( trailer_len >= 8 ) {
 122     vssmonitoring_time.secs  = tvb_get_ntohl(tvb, offset);
 123     vssmonitoring_time.nsecs = tvb_get_ntohl(tvb, offset + 4);
 124     vssmonitoring_clksrc     = (guint8)(((guint32)vssmonitoring_time.nsecs) >> CLKSRC_SHIFT);
 125     vssmonitoring_time.nsecs &= VSS_NS_MASK;
 126
 127     /* There are only heuristics for timestamps, the port stamp can be any value */
 128     if ( vssmonitoring_use_heuristics ) {
 129
 130       /* The timestamp will be based on the uptime until the TAP is completely booted,
 131        * this takes about 60s, but use 1 hour to be sure
 132        */
 133
 134       /* Probably just null data to fill up a short frame.
 135        * FIXME: Should be made even stricter.
 136        */
 137       if (vssmonitoring_time.secs == 0)
 138         return 0;
 139       if (vssmonitoring_time.secs > 3600) {
 140
 141         /* Check whether the timestamp in the PCAP header and the VSS-Monitoring
 142          * differ less than 30 days, otherwise, this might not be a VSS-Monitoring
 143          * timestamp
 144          */
 145         if ( vssmonitoring_time.secs > pinfo->fd->abs_ts.secs ) {
 146           if ( vssmonitoring_time.secs - pinfo->fd->abs_ts.secs > 2592000 ) /* 30 days */
 147             return 0;
 148         } else {
 149           if ( pinfo->fd->abs_ts.secs - vssmonitoring_time.secs > 2592000 ) /* 30 days */
 150             return 0;
 151         }
 152       }
 153
 154       /* The nanoseconds field should be less than 1000000000
 155        */
 156       if ( vssmonitoring_time.nsecs >= 1000000000 )
 157         return 0;
 158     }
 159   }
 160
 161   /* All systems are go, lets dissect the VSS-Monitoring trailer */
 162   if (tree) {
 163     ti = proto_tree_add_item(tree, proto_vssmonitoring,
 164              tvb, 0, (trailer_len & 0xb), ENC_NA);
 165     vssmonitoring_tree = proto_item_add_subtree(ti, ett_vssmonitoring);
 166   }
 167
 168   /* Do we have a timestamp? */
 169   if ( trailer_len >= 8 ) {
 170     if (tree) {
 171       proto_tree_add_time(vssmonitoring_tree, hf_vssmonitoring_time, tvb, offset, 8, &vssmonitoring_time);
 172       proto_tree_add_uint(vssmonitoring_tree, hf_vssmonitoring_clksrc, tvb, offset + 4, 1, vssmonitoring_clksrc);
 173
 174       tmp = localtime(&vssmonitoring_time.secs);
 175       proto_item_append_text(ti, ", Timestamp: %02d:%02d:%02d.%09ld",
 176           tmp->tm_hour, tmp->tm_min, tmp->tm_sec,(long)vssmonitoring_time.nsecs);
 177     }
 178     offset += 8;
 179   }
 180
 181   /* Do we have a portstamp? */
 182   if ( trailer_len & 3) {
 183     if ( trailer_len & 1) {
 184       vssmonitoring_srcport = (guint16)tvb_get_guint8(tvb, offset);
 185       if (tree)
 186         proto_tree_add_item(vssmonitoring_tree, hf_vssmonitoring_srcport, tvb, offset, 1, ENC_NA);
 187       offset++;
 188     } else if ( trailer_len & 2) {
 189       vssmonitoring_srcport = tvb_get_ntohs(tvb, offset);
 190       if (tree)
 191         proto_tree_add_item(vssmonitoring_tree, hf_vssmonitoring_srcport, tvb, offset, 2, ENC_NA);
 192       offset += 2;
 193     }
 194     if (tree)
 195       proto_item_append_text(ti, ", Source Port: %d", vssmonitoring_srcport);
 196   }
 197
 198   return offset;
 199 }
 200
 201 void
 202 proto_register_vssmonitoring(void)
 203 {
 204   static hf_register_info hf[] = {
 205     { &hf_vssmonitoring_time, {
 206         "Time Stamp", "vssmonitoring.time",
 207         FT_ABSOLUTE_TIME, ABSOLUTE_TIME_LOCAL, NULL, 0x0,
 208         "VSS-Monitoring Time Stamp", HFILL }},
 209
 210     { &hf_vssmonitoring_clksrc, {
 211         "Clock Source", "vssmonitoring.clksrc",
 212         FT_UINT8, BASE_DEC, VALS(clksrc_vals), 0x0,
 213         "VSS-Monitoring Clock Source", HFILL }},
 214
 215     { &hf_vssmonitoring_srcport, {
 216         "Src Port", "vssmonitoring.srcport",
 217         FT_UINT8, BASE_DEC, NULL, 0x0,
 218         "VSS-Monitoring Source Port", HFILL }}
 219   };
 220
 221   static gint *ett[] = {
 222     &ett_vssmonitoring
 223   };
 224
 225   module_t *vssmonitoring_module;
 226
 227   proto_vssmonitoring = proto_register_protocol("VSS-Monitoring ethernet trailer", "VSS-Monitoring", "vssmonitoring");
 228   proto_register_field_array(proto_vssmonitoring, hf, array_length(hf));
 229   proto_register_subtree_array(ett, array_length(ett));
 230
 231   vssmonitoring_module = prefs_register_protocol(proto_vssmonitoring, NULL);
 232
 233   prefs_register_bool_preference(vssmonitoring_module, "use_heuristics",
 234       "Use heuristics to verify if trailer contains VSS-Monitoring data",
 235       "When enabled, Wireshark will do a check on the trailer data to verify"
 236       "whether it contains VSS-Monitoring time- and port-stamps.",
 237       &vssmonitoring_use_heuristics);
 238 }
 239
 240 void
 241 proto_reg_handoff_vssmonitoring(void)
 242 {
 243   heur_dissector_add("eth.trailer", dissect_vssmonitoring, proto_vssmonitoring);
 244 }