packet-sll.c

   1 /* packet-sll.c
   2  * Routines for disassembly of packets from Linux "cooked mode" captures
   3  *
   4  * $Id: packet-sll.c,v 1.3 2001/01/03 10:34:41 guy Exp $
   5  *
   6  * Ethereal - Network traffic analyzer
   7  * By Gerald Combs <gerald@zing.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; either version 2
  14  * of the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  24  */
  25
  26 #ifdef HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #ifdef HAVE_SYS_TYPES_H
  31 # include <sys/types.h>
  32 #endif
  33
  34 #include <stdio.h>
  35 #include <string.h>
  36 #include <glib.h>
  37 #include "packet.h"
  38 #include "packet-ipx.h"
  39 #include "packet-llc.h"
  40 #include "resolv.h"
  41
  42 static int proto_sll = -1;
  43 static int hf_sll_pkttype = -1;
  44 static int hf_sll_hatype = -1;
  45 static int hf_sll_halen = -1;
  46 static int hf_sll_src_eth = -1;
  47 static int hf_sll_src_other = -1;
  48 static int hf_sll_ltype = -1;
  49 static int hf_sll_etype = -1;
  50 static int hf_sll_trailer = -1;
  51
  52 static gint ett_sll = -1;
  53
  54 /*
  55  * A DLT_LINUX_SLL fake link-layer header.
  56  */
  57 #define SLL_HEADER_SIZE 16              /* total header length */
  58 #define SLL_ADDRLEN     8               /* length of address field */
  59
  60 /*
  61  * The LINUX_SLL_ values for "sll_pkttype".
  62  */
  63 #define LINUX_SLL_HOST          0
  64 #define LINUX_SLL_BROADCAST     1
  65 #define LINUX_SLL_MULTICAST     2
  66 #define LINUX_SLL_OTHERHOST     3
  67 #define LINUX_SLL_OUTGOING      4
  68
  69 static const value_string packet_type_vals[] = {
  70         { LINUX_SLL_HOST,       "Unicast to us" },
  71         { LINUX_SLL_BROADCAST,  "Broadcast" },
  72         { LINUX_SLL_MULTICAST,  "Multicast" },
  73         { LINUX_SLL_OTHERHOST,  "Unicast to another host" },
  74         { LINUX_SLL_OUTGOING,   "Sent by us" },
  75         { 0,                    NULL }
  76 };
  77
  78 /*
  79  * The LINUX_SLL_ values for "sll_protocol".
  80  */
  81 #define LINUX_SLL_P_802_3       0x0001  /* Novell 802.3 frames without 802.2 LLC header */
  82 #define LINUX_SLL_P_802_2       0x0004  /* 802.2 frames (not D/I/X Ethernet) */
  83
  84 static const value_string ltype_vals[] = {
  85         { LINUX_SLL_P_802_3,    "Raw 802.3" },
  86         { LINUX_SLL_P_802_2,    "802.2 LLC" },
  87         { 0,                    NULL }
  88 };
  89
  90 static dissector_handle_t llc_handle;
  91
  92 void
  93 capture_sll(const u_char *pd, packet_counts *ld)
  94 {
  95         guint16 protocol;
  96
  97         if (!BYTES_ARE_IN_FRAME(0, SLL_HEADER_SIZE)) {
  98                 ld->other++;
  99                 return;
 100         }
 101         protocol = pntohs(&pd[14]);
 102         if (protocol <= 1536) { /* yes, 1536 - that's how Linux does it */
 103                 /*
 104                  * "proto" is *not* a length field, it's a Linux internal
 105                  * protocol type.
 106                  */
 107                 switch (protocol) {
 108
 109                 case LINUX_SLL_P_802_2:
 110                         /*
 111                          * 802.2 LLC.
 112                          */
 113                         capture_llc(pd, SLL_HEADER_SIZE, ld);
 114                         break;
 115
 116                 case LINUX_SLL_P_802_3:
 117                         /*
 118                          * Novell IPX inside 802.3 with no 802.2 LLC
 119                          * header.
 120                          */
 121                         capture_ipx(pd, SLL_HEADER_SIZE, ld);
 122                         break;
 123
 124                 default:
 125                         ld->other++;
 126                         break;
 127                 }
 128         } else
 129                 capture_ethertype(protocol, SLL_HEADER_SIZE, pd, ld);
 130 }
 131
 132 static void
 133 dissect_sll(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 134 {
 135         guint16 pkttype;
 136         guint16 protocol;
 137         guint16 hatype, halen;
 138         guint8 *src;
 139         proto_item *ti;
 140         volatile guint16 length;
 141         tvbuff_t *volatile next_tvb;
 142         tvbuff_t *volatile trailer_tvb;
 143         proto_tree *volatile fh_tree = NULL;
 144         guint length_before;
 145
 146         CHECK_DISPLAY_AS_DATA(proto_sll, tvb, pinfo, tree);
 147
 148         pinfo->current_proto = "SLL";
 149         if (check_col(pinfo->fd, COL_PROTOCOL))
 150                 col_set_str(pinfo->fd, COL_PROTOCOL, "SLL");
 151
 152         pkttype = tvb_get_ntohs(tvb, 0);
 153
 154         if (check_col(pinfo->fd, COL_INFO))
 155                 col_add_str(pinfo->fd, COL_INFO,
 156                     val_to_str(pkttype, packet_type_vals, "Unknown (%u)"));
 157
 158         if (tree) {
 159                 ti = proto_tree_add_protocol_format(tree, proto_sll, tvb, 0,
 160                     SLL_HEADER_SIZE, "Linux cooked capture");
 161                 fh_tree = proto_item_add_subtree(ti, ett_sll);
 162                 proto_tree_add_item(fh_tree, hf_sll_pkttype, tvb, 0, 2, FALSE);
 163         }
 164
 165         /*
 166          * XXX - check the link-layer address type value?
 167          * For now, we just assume 6 means Ethernet.
 168          */
 169         hatype = tvb_get_ntohs(tvb, 2);
 170         halen = tvb_get_ntohs(tvb, 4);
 171         if (tree) {
 172                 proto_tree_add_uint(fh_tree, hf_sll_hatype, tvb, 2, 2, hatype);
 173                 proto_tree_add_uint(fh_tree, hf_sll_halen, tvb, 4, 2, halen);
 174         }
 175         if (halen == 6) {
 176                 src = tvb_get_ptr(tvb, 6, 6);
 177                 SET_ADDRESS(&pinfo->dl_src, AT_ETHER, 6, src);
 178                 SET_ADDRESS(&pinfo->src, AT_ETHER, 6, src);
 179                 if (tree) {
 180                         proto_tree_add_ether(fh_tree, hf_sll_src_eth, tvb,
 181                             6, 6, src);
 182                 }
 183         } else {
 184                 if (tree) {
 185                         proto_tree_add_bytes(fh_tree, hf_sll_src_other, tvb,
 186                             6, halen, tvb_get_ptr(tvb, 6, halen));
 187                 }
 188         }
 189
 190         protocol = tvb_get_ntohs(tvb, 14);
 191         if (protocol <= 1536) { /* yes, 1536 - that's how Linux does it */
 192                 /*
 193                  * "proto" is *not* a length field, it's a Linux internal
 194                  * protocol type.
 195                  * We therefore cannot say how much of the packet will
 196                  * be trailer data.
 197                  * XXX - do the same thing we do for packets with Ethertypes?
 198                  */
 199                 proto_tree_add_uint(fh_tree, hf_sll_ltype, tvb, 14, 2,
 200                     protocol);
 201
 202                 next_tvb = tvb_new_subset(tvb, SLL_HEADER_SIZE, -1, -1);
 203                 trailer_tvb = NULL;
 204                 switch (protocol) {
 205
 206                 case LINUX_SLL_P_802_2:
 207                         /*
 208                          * 802.2 LLC.
 209                          */
 210                         call_dissector(llc_handle, next_tvb, pinfo, tree);
 211                         break;
 212
 213                 case LINUX_SLL_P_802_3:
 214                         /*
 215                          * Novell IPX inside 802.3 with no 802.2 LLC
 216                          * header.
 217                          */
 218                         dissect_ipx(next_tvb, pinfo, tree);
 219                         break;
 220
 221                 default:
 222                         dissect_data(next_tvb, 0, pinfo, tree);
 223                         break;
 224                 }
 225         } else {
 226                 length_before = tvb_reported_length(tvb);
 227                 length = ethertype(protocol, tvb, SLL_HEADER_SIZE, pinfo, tree,
 228                     fh_tree, hf_sll_etype) + SLL_HEADER_SIZE;
 229                 if (length < length_before) {
 230                         /*
 231                          * Create a tvbuff for the padding.
 232                          */
 233                         TRY {
 234                                 trailer_tvb = tvb_new_subset(tvb, length, -1,
 235                                     -1);
 236                         }
 237                         CATCH2(BoundsError, ReportedBoundsError) {
 238                                 /* The packet doesn't have "length" bytes
 239                                    worth of captured data left in it.  No
 240                                    trailer to display. */
 241                                 trailer_tvb = NULL;
 242                         }
 243                         ENDTRY;
 244                 } else {
 245                         /*
 246                          * There is no padding.
 247                          */
 248                         trailer_tvb = NULL;
 249                 }
 250         }
 251
 252         /* If there's some bytes left over, mark them. */
 253         if (trailer_tvb && tree) {
 254                 guint trailer_length;
 255
 256                 trailer_length = tvb_length(trailer_tvb);
 257                 if (trailer_length != 0) {
 258                         proto_tree_add_item(fh_tree, hf_sll_trailer,
 259                             trailer_tvb, 0, trailer_length, FALSE);
 260                 }
 261         }
 262 }
 263
 264 void
 265 proto_register_sll(void)
 266 {
 267         static hf_register_info hf[] = {
 268                 { &hf_sll_pkttype,
 269                 { "Packet type",        "sll.pkttype", FT_UINT16, BASE_DEC,
 270                   VALS(packet_type_vals), 0x0, "Packet type" }},
 271
 272                 /* ARP hardware type?  With Linux extensions? */
 273                 { &hf_sll_hatype,
 274                 { "Link-layer address type",    "sll.hatype", FT_UINT16, BASE_DEC,
 275                   NULL, 0x0, "Link-layer address type" }},
 276
 277                 { &hf_sll_halen,
 278                 { "Link-layer address length",  "sll.halen", FT_UINT16, BASE_DEC,
 279                   NULL, 0x0, "Link-layer address length" }},
 280
 281                 /* Source address if it's an Ethernet-type address */
 282                 { &hf_sll_src_eth,
 283                 { "Source",     "sll.src.eth", FT_ETHER, BASE_NONE, NULL, 0x0,
 284                         "Source link-layer address" }},
 285
 286                 /* Source address if it's not an Ethernet-type address */
 287                 { &hf_sll_src_other,
 288                 { "Source",     "sll.src.other", FT_BYTES, BASE_HEX, NULL, 0x0,
 289                         "Source link-layer address" }},
 290
 291                 /* if the protocol field is an internal Linux protocol type */
 292                 { &hf_sll_ltype,
 293                 { "Protocol",   "sll.ltype", FT_UINT16, BASE_HEX,
 294                    VALS(ltype_vals), 0x0, "Linux protocol type" }},
 295
 296                 /* registered here but handled in ethertype.c */
 297                 { &hf_sll_etype,
 298                 { "Protocol",   "sll.etype", FT_UINT16, BASE_HEX,
 299                    VALS(etype_vals), 0x0, "Ethernet protocol type" }},
 300
 301                 { &hf_sll_trailer,
 302                 { "Trailer", "sll.trailer", FT_BYTES, BASE_NONE, NULL, 0x0,
 303                         "Trailer" }},
 304         };
 305         static gint *ett[] = {
 306                 &ett_sll,
 307         };
 308
 309         proto_sll = proto_register_protocol("Linux cooked-mode capture",
 310             "SLL", "sll" );
 311         proto_register_field_array(proto_sll, hf, array_length(hf));
 312         proto_register_subtree_array(ett, array_length(ett));
 313 }
 314
 315 void
 316 proto_reg_handoff_sll(void)
 317 {
 318         /*
 319          * Get a handle for the LLC dissector.
 320          */
 321         llc_handle = find_dissector("llc");
 322
 323         dissector_add("wtap_encap", WTAP_ENCAP_SLL, dissect_sll);
 324 }