epan/dissectors/packet-prp.c

   1 /* packet-prp.c
   2  * Routines for PRP (Parallel Redundancy Protocol; IEC62439 Part 3) dissection
   3  * Copyright 2007, Sven Meier <msv[AT]zhwin.ch>
   4  * Copyright 2011, Martin Renold <reld[AT]zhaw.ch>
   5  * Copyright 2011, Florian Reichert <refl [AT] zhaw.ch>
   6  *
   7  * $Id$
   8  *
   9  * Wireshark - Network traffic analyzer
  10  * By Gerald Combs <gerald[AT]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 <glib.h>
  31 #include <epan/packet.h>
  32 #include <epan/etypes.h>
  33 #include <epan/prefs.h>
  34
  35 #define    PRP_LAN_A                               10
  36 #define    PRP_LAN_B                               11
  37
  38 static const value_string prp_lan_vals[] = {
  39     {PRP_LAN_A, "LAN A"},
  40     {PRP_LAN_B, "LAN B"},
  41     {0, NULL}
  42 };
  43
  44 /**********************************************************/
  45 /* Initialize the protocol and registered fields      */
  46 /**********************************************************/
  47
  48 void proto_reg_handoff_prp(void);
  49 static int proto_prp = -1;
  50
  51
  52 /* Initialize trailer fields */
  53 static int hf_prp_redundancy_control_trailer_sequence_nr = -1;
  54 static int hf_prp_redundancy_control_trailer_lan = -1;
  55 static int hf_prp_redundancy_control_trailer_size = -1;
  56 static int hf_prp_redundancy_control_trailer_suffix = -1;
  57 static int hf_prp_redundancy_control_trailer_version = -1;
  58
  59
  60 /* Initialize the subtree pointers */
  61 static gint ett_prp_redundancy_control_trailer = -1;
  62
  63
  64 /*  Post dissectors (such as the trailer dissector for this protocol)
  65  *  get called for every single frame anyone loads into Wireshark.
  66  *  Since this protocol is not of general interest we disable this
  67  *  protocol by default.
  68  *
  69  *  This is done separately from the disabled protocols list mainly so
  70  *  we can disable it by default.  XXX Maybe there's a better way.
  71  */
  72 static gboolean prp_enable_dissector = FALSE;
  73
  74
  75 /* Code to actually dissect the packets */
  76 static void
  77 dissect_prp_redundancy_control_trailer(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree)
  78 {
  79     proto_item *ti;
  80     proto_tree *prp_tree;
  81     guint       i;
  82     guint       length;
  83     guint       offset;
  84     guint16     lan_id;
  85     guint16     lsdu_size;
  86     guint16     prp1_suffix;
  87     guint       trailer_start;
  88     guint       trailer_length;
  89
  90     if (!tree)
  91         return;
  92
  93     trailer_start = 0;
  94     trailer_length = 0;
  95     length = tvb_reported_length(tvb);
  96
  97     if(length < 14)
  98     {
  99         return;
 100     }
 101
 102     if(ETHERTYPE_VLAN == tvb_get_ntohs(tvb, 12)) /* tagged frame */
 103     {
 104         offset = 18;
 105     }
 106     else /* untagged */
 107     {
 108         offset = 14;
 109     }
 110
 111     /* search for PRP-0 trailer */
 112     /* If the frame is >  64 bytes, the PRP-0 trailer is always at the end. */
 113     /* If the frame is <= 64 bytes, the PRP-0 trailer may be anywhere (before the padding) */
 114     for(i=length-4; i>=offset; i--)
 115     {
 116         lan_id    = tvb_get_ntohs(tvb, (i+2)) >> 12;
 117         lsdu_size = tvb_get_ntohs(tvb, (i+2)) & 0x0fff;
 118         if(lsdu_size == i+4-offset && (lan_id == 0xa || lan_id == 0xb))
 119         {
 120             trailer_start  = i;
 121             trailer_length = 4;
 122             break;
 123         }
 124
 125         if (length > 64) {
 126             break; /* don't search, just check the last position */
 127         }
 128     }
 129
 130     /* check for PRP-1 trailer */
 131     /* PRP-1 trailer is always at the end of the frame, after any padding. */
 132     {
 133         lan_id      = tvb_get_ntohs(tvb, length-4) >> 12;
 134         lsdu_size   = tvb_get_ntohs(tvb, length-4) & 0x0fff;
 135         prp1_suffix = tvb_get_ntohs(tvb, length-2);
 136
 137         if(prp1_suffix == ETHERTYPE_PRP && (lan_id == 0xa || lan_id == 0xb))
 138         {
 139             /* We don't check the lsdu_size, we just display whether
 140                it's correct. Helpful for testing, because different
 141                definitions of the lsdu_size did exist. */
 142             trailer_start  = length-6;
 143             trailer_length = 6;
 144         }
 145     }
 146
 147     if(trailer_length != 0)
 148     {
 149         /* create display subtree for the protocol */
 150         ti = proto_tree_add_item(tree, proto_prp, tvb, trailer_start,
 151                                  trailer_length, ENC_NA);
 152
 153         prp_tree = proto_item_add_subtree(ti, ett_prp_redundancy_control_trailer);
 154
 155         if (trailer_length == 4) {
 156             ti = proto_tree_add_string(prp_tree, hf_prp_redundancy_control_trailer_version,
 157                                        tvb, trailer_start, trailer_length, "PRP-0");
 158         } else {
 159             ti = proto_tree_add_string(prp_tree, hf_prp_redundancy_control_trailer_version,
 160                                        tvb, trailer_start, trailer_length, "PRP-1");
 161         }
 162         PROTO_ITEM_SET_GENERATED(ti);
 163
 164         proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_sequence_nr,
 165                             tvb, trailer_start, 2, ENC_BIG_ENDIAN);
 166
 167         proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_lan,
 168                             tvb, trailer_start+2, 2, ENC_BIG_ENDIAN);
 169
 170         if (trailer_length == 4) {
 171             /* PRP-0 */
 172             proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_size,
 173                                 tvb, trailer_start+2, 2, ENC_BIG_ENDIAN);
 174         } else {
 175             /* PRP-1 */
 176             int lsdu_size_correct = length-offset;
 177             if (lsdu_size == lsdu_size_correct) {
 178                 proto_tree_add_uint_format(prp_tree, hf_prp_redundancy_control_trailer_size,
 179                                            tvb, trailer_start+2, 2, lsdu_size,
 180                                            "LSDU size: %d [correct]", lsdu_size);
 181             } else {
 182                 proto_tree_add_uint_format(prp_tree, hf_prp_redundancy_control_trailer_size,
 183                                            tvb, trailer_start+2, 2, lsdu_size,
 184                                            "LSDU size: %d [WRONG, should be %d]", lsdu_size, lsdu_size_correct);
 185             }
 186             /* suffix */
 187             proto_tree_add_item(prp_tree, hf_prp_redundancy_control_trailer_suffix,
 188                                 tvb, trailer_start+4, 2, ENC_BIG_ENDIAN);
 189         }
 190     }
 191 }
 192
 193 /* Register the protocol with Wireshark */
 194 void proto_register_prp(void)
 195 {
 196     static hf_register_info hf[] = {
 197         /*trailer*/
 198         { &hf_prp_redundancy_control_trailer_sequence_nr,
 199             { "Sequence number", "prp.trailer.prp_sequence_nr",
 200             FT_UINT16, BASE_DEC, NULL, 0x00,
 201             NULL, HFILL }
 202         },
 203
 204         { &hf_prp_redundancy_control_trailer_lan,
 205             { "LAN", "prp.trailer.prp_lan",
 206             FT_UINT16, BASE_DEC, VALS(prp_lan_vals), 0xf000,
 207             NULL, HFILL }
 208         },
 209
 210         { &hf_prp_redundancy_control_trailer_size,
 211             { "Size", "prp.trailer.prp_size",
 212             FT_UINT16, BASE_DEC, NULL, 0x0fff,
 213             NULL, HFILL }
 214         },
 215
 216         { &hf_prp_redundancy_control_trailer_suffix,
 217             { "Suffix", "prp.trailer.prp1_suffix",
 218             FT_UINT16, BASE_HEX, NULL, 0x00,
 219             NULL, HFILL }
 220         },
 221
 222         { &hf_prp_redundancy_control_trailer_version,
 223             { "PRP Version", "prp.trailer.version",
 224             FT_STRING, BASE_NONE, NULL, 0x00,
 225             NULL, HFILL }
 226         }
 227     };
 228
 229     static gint *ett[] = {
 230         &ett_prp_redundancy_control_trailer,
 231     };
 232
 233     module_t *prp_module;
 234
 235     /* Register the protocol name and description */
 236     proto_prp = proto_register_protocol("Parallel Redundancy Protocol (IEC62439 Part 3)",
 237                         "PRP", "prp");
 238     prp_module = prefs_register_protocol(proto_prp, proto_reg_handoff_prp);
 239
 240     prefs_register_bool_preference(prp_module, "enable", "Enable dissector",
 241                        "Enable this dissector (default is false)",
 242                        &prp_enable_dissector);
 243
 244     /* Required function calls to register the header fields and subtree used */
 245     proto_register_field_array(proto_prp, hf, array_length(hf));
 246     proto_register_subtree_array(ett, array_length(ett));
 247
 248 }
 249
 250 void proto_reg_handoff_prp(void)
 251 {
 252     static gboolean prefs_initialized = FALSE;
 253
 254     if (!prefs_initialized) {
 255         dissector_handle_t prp_redundancy_control_trailer_handle;
 256
 257         prp_redundancy_control_trailer_handle = create_dissector_handle(dissect_prp_redundancy_control_trailer, proto_prp);
 258         register_postdissector(prp_redundancy_control_trailer_handle);
 259
 260         prefs_initialized = TRUE;
 261     }
 262
 263     proto_set_decoding(proto_prp, prp_enable_dissector);
 264 }