packet-ethertype.c

   1 /* ethertype.c
   2  * Routines for calling the right protocol for the ethertype.
   3  *
   4  * $Id: packet-ethertype.c,v 1.21 2001/11/20 21:59:12 guy Exp $
   5  *
   6  * Gilbert Ramirez <gram@alumni.rice.edu>
   7  *
   8  * Ethereal - Network traffic analyzer
   9  * By Gerald Combs <gerald@ethereal.com>
  10  * Copyright 1998 Gerald Combs
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  25  */
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #ifdef HAVE_SYS_TYPES_H
  32 # include <sys/types.h>
  33 #endif
  34
  35 #include <glib.h>
  36 #include "packet.h"
  37 #include "packet-ip.h"
  38 #include "packet-ipx.h"
  39 #include "packet-vlan.h"
  40 #include "packet-vines.h"
  41 #include "etypes.h"
  42 #include "ppptypes.h"
  43
  44 static dissector_table_t ethertype_dissector_table;
  45
  46 const value_string etype_vals[] = {
  47     {ETHERTYPE_IP,              "IP"                            },
  48     {ETHERTYPE_IPv6,            "IPv6"                          },
  49     {ETHERTYPE_X25L3,           "X.25 Layer 3"                  },
  50     {ETHERTYPE_ARP,             "ARP"                           },
  51     {ETHERTYPE_REVARP,          "RARP"                          },
  52     {ETHERTYPE_DEC_LB,          "DEC LanBridge"                 },
  53     {ETHERTYPE_ATALK,           "Appletalk"                     },
  54     {ETHERTYPE_AARP,            "AARP"                          },
  55     {ETHERTYPE_IPX,             "Netware IPX/SPX"               },
  56     {ETHERTYPE_VINES,           "Vines"                         },
  57     {ETHERTYPE_TRAIN,           "Netmon Train"                  },
  58     {ETHERTYPE_LOOP,            "Loopback"                      }, /* Ethernet Loopback */
  59     {ETHERTYPE_WCP,             "Wellfleet Compression Protocol" },
  60     {ETHERTYPE_PPPOED,          "PPPoE Discovery"               },
  61     {ETHERTYPE_PPPOES,          "PPPoE Session"                 },
  62     {ETHERTYPE_VLAN,            "802.1Q Virtual LAN"            },
  63     {ETHERTYPE_EAPOL,           "802.1X Authentication"         },
  64     {ETHERTYPE_MPLS,            "MPLS label switched packet"    },
  65     {ETHERTYPE_MPLS_MULTI,      "MPLS multicast label switched packet" },
  66     {ETHERTYPE_3C_NBP_DGRAM,    "3Com NBP Datagram"             },
  67     {ETHERTYPE_DEC,             "DEC proto"                     },
  68     {ETHERTYPE_DNA_DL,          "DEC DNA Dump/Load"             },
  69     {ETHERTYPE_DNA_RC,          "DEC DNA Remote Console"        },
  70     {ETHERTYPE_DNA_RT,          "DEC DNA Routing"               },
  71     {ETHERTYPE_LAT,             "DEC LAT"                       },
  72     {ETHERTYPE_DEC_DIAG,        "DEC Diagnostics"               },
  73     {ETHERTYPE_DEC_CUST,        "DEC Customer use"              },
  74     {ETHERTYPE_DEC_SCA,         "DEC LAVC/SCA"                  },
  75     {ETHERTYPE_ETHBRIDGE,       "Transparent Ethernet bridging" },
  76
  77     /*
  78      * NDISWAN on Windows translates Ethernet frames from higher-level
  79      * protocols into PPP frames to hand to the PPP driver, and translates
  80      * PPP frames from the PPP driver to hand to the higher-level protocols.
  81      *
  82      * Apparently the PPP driver, on at least some versions of Windows,
  83      * passes frames for internal-to-PPP protocols up through NDISWAN;
  84      * the protocol type field appears to be passed through unchanged
  85      * (unlike what's done with, for example, the protocol type field
  86      * for IP, which is mapped from its PPP value to its Ethernet value).
  87      *
  88      * This means that we may see, on Ethernet captures, frames for
  89      * protocols internal to PPP, so we list as "Ethernet" protocol
  90      * types the PPP protocol types we've seen.
  91      */
  92     {PPP_IPCP,                  "PPP IP Control Protocol" },
  93     {PPP_LCP,                   "PPP Link Control Protocol" },
  94     {PPP_PAP,                   "PPP Password Authentication Protocol" },
  95     {PPP_CCP,                   "PPP Compression Control Protocol" },
  96     {0,                         NULL                            } };
  97
  98 static void add_trailer(proto_tree *fh_tree, int trailer_id, tvbuff_t *tvb,
  99     tvbuff_t *next_tvb, int offset_after_etype, guint length_before);
 100
 101 void
 102 capture_ethertype(guint16 etype, const u_char *pd, int offset, int len,
 103                   packet_counts *ld)
 104 {
 105   switch (etype) {
 106     case ETHERTYPE_IP:
 107       capture_ip(pd, offset, len, ld);
 108       break;
 109     case ETHERTYPE_IPX:
 110       capture_ipx(pd, offset, len, ld);
 111       break;
 112     case ETHERTYPE_VLAN:
 113       capture_vlan(pd, offset, len, ld);
 114       break;
 115     case ETHERTYPE_VINES:
 116       capture_vines(pd, offset, len, ld);
 117       break;
 118     default:
 119       ld->other++;
 120       break;
 121   }
 122 }
 123
 124 void
 125 ethertype(guint16 etype, tvbuff_t *tvb, int offset_after_etype,
 126                 packet_info *pinfo, proto_tree *tree, proto_tree *fh_tree,
 127                 int etype_id, int trailer_id)
 128 {
 129         char                    *description;
 130         tvbuff_t                *next_tvb;
 131         guint                   length_before;
 132         volatile gboolean       dissector_found;
 133
 134         /* Add to proto_tree */
 135         if (tree) {
 136                 proto_tree_add_uint(fh_tree, etype_id, tvb,
 137                     offset_after_etype - 2, 2, etype);
 138         }
 139
 140         /* Tvbuff for the payload after the Ethernet type. */
 141         next_tvb = tvb_new_subset(tvb, offset_after_etype, -1, -1);
 142
 143         pinfo->ethertype = etype;
 144
 145         /* Remember how much data there is in it. */
 146         length_before = tvb_reported_length(next_tvb);
 147
 148         /* Look for sub-dissector, and call it if found.
 149            Catch BoundsError and ReportedBoundsError, so that if the
 150            reported length of "next_tvb" was reduced by some dissector
 151            before an exception was thrown, we can still put in an item
 152            for the trailer. */
 153         TRY {
 154                 dissector_found = dissector_try_port(ethertype_dissector_table,
 155                     etype, next_tvb, pinfo, tree);
 156         }
 157         CATCH2(BoundsError, ReportedBoundsError) {
 158                 /* Well, somebody threw an exception; that means that a
 159                    dissector was found, so we don't need to dissect
 160                    the payload as data or update the protocol or info
 161                    columns. */
 162                 dissector_found = TRUE;
 163
 164                 /* Add the trailer, if appropriate. */
 165                 add_trailer(fh_tree, trailer_id, tvb, next_tvb,
 166                     offset_after_etype, length_before);
 167
 168                 /* Rrethrow the exception, so the "Short Frame" or "Mangled
 169                    Frame" indication can be put into the tree. */
 170                 RETHROW;
 171
 172                 /* XXX - RETHROW shouldn't return. */
 173                 g_assert_not_reached();
 174         }
 175         ENDTRY;
 176
 177         if (!dissector_found) {
 178                 /* No sub-dissector found.
 179                    Label rest of packet as "Data" */
 180                 dissect_data(next_tvb, 0, pinfo, tree);
 181
 182                 /* Label protocol */
 183                 switch (etype) {
 184
 185                 case ETHERTYPE_LOOP:
 186                         if (check_col(pinfo->fd, COL_PROTOCOL)) {
 187                                 col_add_fstr(pinfo->fd, COL_PROTOCOL, "LOOP");
 188                         }
 189                         break;
 190
 191                 default:
 192                         if (check_col(pinfo->fd, COL_PROTOCOL)) {
 193                                 col_add_fstr(pinfo->fd, COL_PROTOCOL, "0x%04x",
 194                                     etype);
 195                         }
 196                         break;
 197                 }
 198                 if (check_col(pinfo->fd, COL_INFO)) {
 199                         description = match_strval(etype, etype_vals);
 200                         if (description) {
 201                                 col_add_fstr(pinfo->fd, COL_INFO, "%s",
 202                                     description);
 203                         }
 204                 }
 205         }
 206
 207         add_trailer(fh_tree, trailer_id, tvb, next_tvb, offset_after_etype,
 208             length_before);
 209 }
 210
 211 static void
 212 add_trailer(proto_tree *fh_tree, int trailer_id, tvbuff_t *tvb,
 213     tvbuff_t *next_tvb, int offset_after_etype, guint length_before)
 214 {
 215         guint           length;
 216         tvbuff_t        *volatile trailer_tvb;
 217
 218         if (fh_tree == NULL)
 219                 return; /* we're not building a protocol tree */
 220
 221         if (trailer_id == -1)
 222                 return; /* our caller doesn't care about trailers */
 223
 224         /* OK, how much is there in that tvbuff now? */
 225         length = tvb_reported_length(next_tvb);
 226
 227         /* If there's less than there was before, what's left is
 228            a trailer. */
 229         if (length < length_before) {
 230                 /*
 231                  * Create a tvbuff for the padding.
 232                  */
 233                 TRY {
 234                         trailer_tvb = tvb_new_subset(tvb,
 235                             offset_after_etype + length, -1, -1);
 236                 }
 237                 CATCH2(BoundsError, ReportedBoundsError) {
 238                         /* The packet doesn't have "length" bytes worth of
 239                            captured data left in it.  No trailer to display. */
 240                         trailer_tvb = NULL;
 241                 }
 242                 ENDTRY;
 243         } else
 244                 trailer_tvb = NULL;     /* no trailer */
 245
 246         /* If there's some bytes left over, and we were given an item ID
 247            for a trailer, mark those bytes as a trailer. */
 248         if (trailer_tvb) {
 249                 guint   trailer_length;
 250
 251                 trailer_length = tvb_length(trailer_tvb);
 252                 if (trailer_length != 0) {
 253                         proto_tree_add_item(fh_tree, trailer_id, trailer_tvb, 0,
 254                             trailer_length, FALSE);
 255                 }
 256         }
 257 }
 258
 259
 260 void
 261 proto_register_ethertype(void)
 262 {
 263         /* subdissector code */
 264         ethertype_dissector_table = register_dissector_table("ethertype");
 265 }