epan/dissectors/packet-pw-eth.c

   1 /* packet-pw-eth.c
   2  * Routines for ethernet PW dissection: it should be conform to RFC 4448.
   3  *
   4  * Copyright 2008 _FF_
   5  *
   6  * Francesco Fondelli <francesco dot fondelli, gmail dot com>
   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 #ifdef HAVE_CONFIG_H
  30 # include "config.h"
  31 #endif
  32
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <glib.h>
  37 #include <epan/packet.h>
  38 #include <epan/addr_resolv.h>
  39
  40 #include "packet-mpls.h"
  41
  42 static gint proto_pw_eth_cw = -1;
  43 static gint proto_pw_eth_nocw = -1;
  44 static gint proto_pw_eth_heuristic = -1;
  45
  46 static gint ett_pw_eth = -1;
  47
  48 static int hf_pw_eth = -1;
  49 static int hf_pw_eth_cw = -1;
  50 static int hf_pw_eth_cw_sequence_number = -1;
  51
  52 static dissector_handle_t eth_withoutfcs_handle;
  53 static dissector_handle_t pw_eth_handle_cw;
  54 static dissector_handle_t pw_eth_handle_nocw;
  55
  56 static void
  57 dissect_pw_eth_cw(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  58 {
  59         proto_tree *pw_eth_tree = NULL;
  60         proto_item *ti = NULL;
  61         tvbuff_t *next_tvb = NULL;
  62         guint16 sequence_number = 0;
  63
  64         if (tvb_reported_length_remaining(tvb, 0) < 4) {
  65                 if (tree)
  66                         proto_tree_add_text(tree, tvb, 0, -1,
  67                                             "Error processing Message");
  68                 return;
  69         }
  70
  71         if (dissect_try_cw_first_nibble(tvb, pinfo, tree))
  72                 return;
  73
  74         sequence_number = tvb_get_ntohs(tvb, 2);
  75         if (tree) {
  76                 ti = proto_tree_add_boolean(tree, hf_pw_eth_cw,
  77                                             tvb, 0, 0, TRUE);
  78                 PROTO_ITEM_SET_HIDDEN(ti);
  79                 ti = proto_tree_add_item(tree, proto_pw_eth_cw,
  80                                          tvb, 0, 4, FALSE);
  81                 pw_eth_tree = proto_item_add_subtree(ti, ett_pw_eth);
  82                 if (pw_eth_tree == NULL)
  83                         return;
  84                 proto_tree_add_uint_format(pw_eth_tree,
  85                                            hf_pw_eth_cw_sequence_number,
  86                                            tvb, 2, 2, sequence_number,
  87                                            "Sequence Number: %d",
  88                                            sequence_number);
  89         }
  90         next_tvb = tvb_new_subset_remaining(tvb, 4);
  91         {
  92                 /*
  93                  * When Ethernet frames being decoded, pinfo->ethertype is extracted
  94                  * from the top-level Ethernet frame. Dissection of Ethernet PW payload
  95                  * overwrites this value as the same dissector is invoked again.
  96                  * This may lead to undesired behavior (like disappearance of "Link"
  97                  * tab from the "Decode as" menu).
  98                  *
  99                  * Let's save/restore ethertype. --ATA
 100                  *
 101                  * XXX it looks that more pinfo members (or even the whole pinfo)
 102                  * XXX should be saved/restored in PW cases. Multilayer encapsulations,
 103                  * XXX like ethernet/mpls/ethernet-pw/ip/vlan, may lead to undesired
 104                  * XXX changes if pinfo->ipproto, ptype etc.
 105                  */
 106                 guint32 etype_save = pinfo->ethertype;
 107                 call_dissector(eth_withoutfcs_handle, next_tvb, pinfo, tree);
 108                 pinfo->ethertype = etype_save;
 109         }
 110 }
 111
 112 static void
 113 dissect_pw_eth_nocw(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 114 {
 115         tvbuff_t *next_tvb = NULL;
 116         proto_item *ti = NULL;
 117
 118         if (tree) {
 119                 ti = proto_tree_add_boolean(tree, hf_pw_eth, tvb, 0, 0, TRUE);
 120                 PROTO_ITEM_SET_HIDDEN(ti);
 121         }
 122         next_tvb = tvb_new_subset_remaining(tvb, 0);
 123         {
 124                 guint32 etype_save = pinfo->ethertype;
 125                 call_dissector(eth_withoutfcs_handle, next_tvb, pinfo, tree);
 126                 pinfo->ethertype = etype_save;
 127         }
 128 }
 129
 130 /*
 131  * FF: this function returns TRUE if the first 12 bytes in tvb looks like
 132  *     two valid ethernet addresses.  FALSE otherwise.
 133  */
 134 static gboolean
 135 looks_like_plain_eth(tvbuff_t *tvb _U_)
 136 {
 137         const gchar *manuf_name_da = NULL;
 138         const gchar *manuf_name_sa = NULL;
 139
 140         if (tvb_reported_length_remaining(tvb, 0) < 14) {
 141                 return FALSE;
 142         }
 143
 144         manuf_name_da = get_manuf_name_if_known(tvb_get_ptr(tvb, 0, 6));
 145         manuf_name_sa = get_manuf_name_if_known(tvb_get_ptr(tvb, 6, 6));
 146
 147         if (manuf_name_da && manuf_name_sa) {
 148                 return TRUE;
 149         }
 150
 151         return FALSE;
 152 }
 153
 154 static void
 155 dissect_pw_eth_heuristic(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 156 {
 157         if (looks_like_plain_eth(tvb)) {
 158                 call_dissector(pw_eth_handle_nocw, tvb, pinfo, tree);
 159         } else {
 160                 call_dissector(pw_eth_handle_cw, tvb, pinfo, tree);
 161         }
 162 }
 163
 164 void
 165 proto_register_pw_eth(void)
 166 {
 167         static hf_register_info hf[] = {
 168                 {
 169                         &hf_pw_eth,
 170                         {
 171                                 "PW (ethernet)",
 172                                 "pweth", FT_BOOLEAN,
 173                                 BASE_NONE, NULL, 0x0, NULL, HFILL
 174                         }
 175                 },
 176                 {
 177                         &hf_pw_eth_cw,
 178                         {
 179                                 "PW Control Word (ethernet)",
 180                                 "pweth.cw", FT_BOOLEAN,
 181                                 BASE_NONE, NULL, 0x0, NULL, HFILL
 182                         }
 183                 },
 184                 {
 185                         &hf_pw_eth_cw_sequence_number,
 186                         {
 187                                 "PW sequence number (ethernet)",
 188                                 "pweth.cw.sequence_number", FT_UINT16,
 189                                 BASE_DEC, NULL, 0x0, NULL, HFILL
 190                         }
 191                 }
 192         };
 193
 194         static gint *ett[] = {
 195                 &ett_pw_eth
 196         };
 197
 198         proto_pw_eth_cw =
 199           proto_register_protocol("PW Ethernet Control Word",
 200                                   "Ethernet PW (with CW)",
 201                                   "pwethcw");
 202         proto_pw_eth_nocw =
 203           proto_register_protocol("Ethernet PW (no CW)", /* not displayed */
 204                                   "Ethernet PW (no CW)",
 205                                   "pwethnocw");
 206         proto_pw_eth_heuristic =
 207           proto_register_protocol("Ethernet PW (CW heuristic)", /* not disp. */
 208                                   "Ethernet PW (CW heuristic)",
 209                                   "pwethheuristic");
 210         proto_register_field_array(proto_pw_eth_cw, hf, array_length(hf));
 211         proto_register_subtree_array(ett, array_length(ett));
 212         register_dissector("pw_eth_cw", dissect_pw_eth_cw, proto_pw_eth_cw);
 213         register_dissector("pw_eth_nocw", dissect_pw_eth_nocw,
 214                            proto_pw_eth_nocw);
 215         register_dissector("pw_eth_heuristic", dissect_pw_eth_heuristic,
 216                            proto_pw_eth_heuristic);
 217 }
 218
 219 void
 220 proto_reg_handoff_pw_eth(void)
 221 {
 222         dissector_handle_t pw_eth_handle_heuristic;
 223
 224         eth_withoutfcs_handle = find_dissector("eth_withoutfcs");
 225
 226         pw_eth_handle_cw = find_dissector("pw_eth_cw");
 227         dissector_add("mpls.label", LABEL_INVALID, pw_eth_handle_cw);
 228
 229         pw_eth_handle_nocw = find_dissector("pw_eth_nocw");
 230         dissector_add("mpls.label", LABEL_INVALID, pw_eth_handle_nocw);
 231
 232         pw_eth_handle_heuristic = find_dissector("pw_eth_heuristic");
 233         dissector_add("mpls.label", LABEL_INVALID, pw_eth_handle_heuristic);
 234 }