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