epan/dissectors/packet-ixiatrailer.c

   1 /* packet-ixiatrailer.c
   2  * Routines for Ixia trailer parsing
   3  *
   4  * Dissector for Ixia Network Visibility Solutions trailer
   5  * Copyright Ixia 2012
   6  *
   7  * $Id$
   8  *
   9  * Wireshark - Network traffic analyzer
  10  * By Gerald Combs <gerald@wireshark.org>
  11  * Copyright 1998 Gerald Combs
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * as published by the Free Software Foundation; either version 2
  16  * of the License, or (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  26  */
  27
  28 #include "config.h"
  29
  30 #include <epan/packet.h>
  31 #include <wsutil/pint.h>
  32 #include <epan/prefs.h>
  33 #include <epan/in_cksum.h>
  34 #include <epan/expert.h>
  35
  36 #define IXIA_PATTERN    0xAF12
  37
  38 /* TODO: which of these typestamp types are currently supported?
  39    Should lose the rest!! */
  40 #define IXIATRAILER_FTYPE_TIMESTAMP_LOCAL     3
  41 #define IXIATRAILER_FTYPE_TIMESTAMP_NTP       4
  42 #define IXIATRAILER_FTYPE_TIMESTAMP_GPS       5
  43 #define IXIATRAILER_FTYPE_TIMESTAMP_1588      6 /* PTP */
  44 #define IXIATRAILER_FTYPE_TIMESTAMP_HOLDOVER  7
  45
  46 static const value_string ixiatrailer_ftype_timestamp[] = {
  47   { IXIATRAILER_FTYPE_TIMESTAMP_LOCAL,      "Local" },
  48   { IXIATRAILER_FTYPE_TIMESTAMP_NTP,        "NTP" },
  49   { IXIATRAILER_FTYPE_TIMESTAMP_GPS,        "GPS" },
  50   { IXIATRAILER_FTYPE_TIMESTAMP_1588,       "PTP" },
  51   { IXIATRAILER_FTYPE_TIMESTAMP_HOLDOVER,   "Holdover" },
  52   { 0,                                      NULL }
  53 };
  54
  55 /* Preference settings */
  56 static gboolean ixiatrailer_summary_in_tree = TRUE;
  57
  58 static int proto_ixiatrailer = -1;
  59 static gint ett_ixiatrailer = -1;
  60
  61 static int hf_ixiatrailer_timestamp = -1;
  62 static int hf_ixiatrailer_generic = -1;
  63
  64 static expert_field ei_ixiatrailer_field_length_invalid = EI_INIT;
  65
  66 /* Format is as follows:
  67    - Time Sync source (1 byte)
  68    - Length of time (1 byte - value will always be 8)
  69    - Timestamp (8 bytes)
  70    - Trailer length -previous fields, always 10 (1 byte)
  71    - Ixia signature - AF12 (2 bytes)
  72    - FCS for IXIA timestamp - covers 13 bytes of all previous fields (2 bytes)
  73 */
  74 static int
  75 dissect_ixiatrailer(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, void *data _U_)
  76 {
  77     proto_tree *ti;
  78     guint tvblen, trailer_length, time_length;
  79     proto_tree *ixiatrailer_tree = NULL;
  80     guint offset = 0;
  81     guint16 cksum, comp_cksum;
  82     vec_t vec;
  83     guint8 source;
  84
  85     /* Need at least 5 bytes.  TODO: should be 15? */
  86     tvblen = tvb_length(tvb);
  87     if (tvblen < 5) {
  88         return 0;
  89     }
  90
  91     /* Depending upon the ethernet preference "Assume packets have FCS", we
  92        may be given those 4 bytes too.  If we see 19 bytes, assume we are
  93        getting them and only look at first 15. */
  94     if (tvblen == 19) {
  95         tvblen = 15;
  96     }
  97
  98     /* 3rd & 4th bytes from the end must match our pattern */
  99     if (tvb_get_ntohs(tvb, tvblen-4) != IXIA_PATTERN) {
 100         return 0;
 101     }
 102
 103     /* Read Trailer-length field */
 104     trailer_length  = tvb_get_guint8(tvb, tvblen-5);
 105     /* Should match overall length of trailer */
 106     if ((tvblen-5) != trailer_length) {
 107         return 0;
 108     }
 109
 110     /* Last 2 bytes are the checksum */
 111     cksum = tvb_get_ntohs(tvb, tvblen-2);
 112
 113     /* Verify the checksum; if not valid, it means that the trailer is not valid */
 114     vec.len = trailer_length + 3;
 115     vec.ptr = tvb_get_ptr(tvb, offset, vec.len);
 116     comp_cksum = in_cksum(&vec, 1);
 117     if (pntohs(&comp_cksum) != cksum) {
 118         return 0;
 119     }
 120
 121     /* OK: We have our trailer - create protocol root */
 122     ti = proto_tree_add_item(tree, proto_ixiatrailer, tvb, offset, trailer_length + 5, ENC_NA);
 123
 124     /* Append summary to item, if configured to */
 125     if (ixiatrailer_summary_in_tree) {
 126         proto_item_append_text(ti, ", Length: %u, Checksum: 0x%x", trailer_length, cksum);
 127     }
 128
 129     /* Create subtree */
 130     ixiatrailer_tree = proto_item_add_subtree(ti, ett_ixiatrailer);
 131
 132     source = tvb_get_guint8(tvb, offset++);
 133     time_length = tvb_get_guint8(tvb, offset++);
 134
 135     switch (source) {
 136         case IXIATRAILER_FTYPE_TIMESTAMP_LOCAL:
 137         case IXIATRAILER_FTYPE_TIMESTAMP_NTP:
 138         case IXIATRAILER_FTYPE_TIMESTAMP_GPS:
 139         case IXIATRAILER_FTYPE_TIMESTAMP_1588:
 140         case IXIATRAILER_FTYPE_TIMESTAMP_HOLDOVER:
 141             if (time_length != 8) {
 142                 expert_add_info_format(pinfo, ti, &ei_ixiatrailer_field_length_invalid, "Field length %u invalid", time_length);
 143                 break;
 144             }
 145             /* Timestamp */
 146             ti = proto_tree_add_item(ixiatrailer_tree, hf_ixiatrailer_timestamp, tvb, offset, time_length, ENC_TIME_TIMESPEC|ENC_BIG_ENDIAN);
 147             proto_item_append_text(ti, "; Source: %s", val_to_str_const(source, ixiatrailer_ftype_timestamp, "Unknown"));
 148             break;
 149
 150       default:
 151             /* Not a recognised time format - just show as bytes */
 152             ti = proto_tree_add_item(ixiatrailer_tree, hf_ixiatrailer_generic, tvb, offset, time_length, ENC_NA);
 153             proto_item_append_text(ti, " [Id: %u, Length: %u]", source, time_length);
 154             break;
 155     }
 156
 157     /* We are claiming all of the bytes */
 158     return tvblen;
 159 }
 160
 161 void
 162 proto_register_ixiatrailer(void)
 163 {
 164
 165   static hf_register_info hf[] = {
 166     { &hf_ixiatrailer_timestamp, {
 167         "Time Stamp", "ixiatrailer.timestamp", FT_ABSOLUTE_TIME, ABSOLUTE_TIME_LOCAL,
 168         NULL, 0x0, NULL, HFILL }},
 169     { &hf_ixiatrailer_generic, {
 170         "Generic Field", "ixiatrailer.generic", FT_BYTES, BASE_NONE,
 171         NULL, 0x0, NULL, HFILL }},
 172   };
 173
 174   static gint *ixiatrailer_ett[] = {
 175     &ett_ixiatrailer
 176   };
 177
 178   static ei_register_info ei[] = {
 179      { &ei_ixiatrailer_field_length_invalid, { "ixiatrailer.field_length_invalid", PI_MALFORMED, PI_ERROR, "Field length invalid", EXPFILL }},
 180   };
 181
 182   module_t *ixiatrailer_module;
 183   expert_module_t* expert_ixiatrailer;
 184
 185   proto_ixiatrailer = proto_register_protocol("Ixia Trailer", "IXIATRAILER", "ixiatrailer");
 186   proto_register_field_array(proto_ixiatrailer, hf, array_length(hf));
 187   proto_register_subtree_array(ixiatrailer_ett, array_length(ixiatrailer_ett));
 188   expert_ixiatrailer = expert_register_protocol(proto_ixiatrailer);
 189   expert_register_field_array(expert_ixiatrailer, ei, array_length(ei));
 190
 191   ixiatrailer_module = prefs_register_protocol(proto_ixiatrailer, NULL);
 192   prefs_register_bool_preference(ixiatrailer_module, "summary_in_tree",
 193         "Show trailer summary in protocol tree",
 194         "Whether the trailer summary line should be shown in the protocol tree",
 195         &ixiatrailer_summary_in_tree);
 196 }
 197
 198
 199 void
 200 proto_reg_handoff_ixiatrailer(void)
 201 {
 202   /* Check for Ixia format in the ethernet trailer */
 203   heur_dissector_add("eth.trailer", dissect_ixiatrailer, proto_ixiatrailer);
 204 }