packet-llc.c

   1 /* packet-llc.c
   2  * Routines for IEEE 802.2 LLC layer
   3  * Gilbert Ramirez <gram@xiexie.org>
   4  *
   5  * $Id: packet-llc.c,v 1.80 2001/01/11 07:24:17 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@zing.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  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 "oui.h"
  38 #include "xdlc.h"
  39 #include "etypes.h"
  40 #include "llcsaps.h"
  41 #include "bridged_pids.h"
  42 #include "packet-ip.h"
  43 #include "packet-ipx.h"
  44 #include "packet-netbios.h"
  45 #include "packet-osi.h"
  46 #include "packet-sna.h"
  47
  48 #include "packet-llc.h"
  49
  50 static int proto_llc = -1;
  51 static int hf_llc_dsap = -1;
  52 static int hf_llc_ssap = -1;
  53 static int hf_llc_dsap_ig = -1;
  54 static int hf_llc_ssap_cr = -1;
  55 static int hf_llc_ctrl = -1;
  56 static int hf_llc_type = -1;
  57 static int hf_llc_oui = -1;
  58 static int hf_llc_pid = -1;
  59
  60 static gint ett_llc = -1;
  61 static gint ett_llc_ctrl = -1;
  62
  63 static dissector_table_t subdissector_table;
  64 static dissector_table_t cisco_subdissector_table;
  65
  66 static dissector_handle_t bpdu_handle;
  67 static dissector_handle_t eth_handle;
  68 static dissector_handle_t fddi_handle;
  69 static dissector_handle_t tr_handle;
  70
  71 typedef void (capture_func_t)(const u_char *, int, packet_counts *);
  72
  73 /* The SAP info is split into two tables, one value_string table and one
  74  * table of sap_info. This is so that the value_string can be used in the
  75  * header field registration.
  76  */
  77 struct sap_info {
  78         guint8  sap;
  79         capture_func_t *capture_func;
  80 };
  81
  82 /*
  83  * Group/Individual bit, in the DSAP.
  84  */
  85 #define DSAP_GI_BIT     0x01
  86
  87 /*
  88  * Command/Response bit, in the SSAP.
  89  *
  90  * The low-order bit of the SSAP apparently determines whether this
  91  * is a request or a response.  (RFC 1390, "Transmission of IP and
  92  * ARP over FDDI Networks", says
  93  *
  94  *      Command frames are identified by having the low order
  95  *      bit of the SSAP address reset to zero.  Response frames
  96  *      have the low order bit of the SSAP address set to one.
  97  *
  98  * and a page I've seen seems to imply that's part of 802.2.)
  99  */
 100 #define SSAP_CR_BIT     0x01
 101
 102 /*
 103  * Mask to extrace the SAP number from the DSAP or the SSAP.
 104  */
 105 #define SAP_MASK        0xFE
 106
 107 /*
 108  * These are for SSAP and DSAP, wth last bit always zero.
 109  * XXX - some DSAPs come in separate "individual" and "group" versions,
 110  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
 111  * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
 112  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
 113  */
 114 static const value_string sap_vals[] = {
 115         { SAP_NULL,           "NULL LSAP" },
 116         { SAP_LLC_SLMGMT,     "LLC Sub-Layer Management" },
 117         { SAP_SNA_PATHCTRL,   "SNA Path Control" },
 118         { SAP_IP,             "TCP/IP" },
 119         { SAP_SNA1,           "SNA" },
 120         { SAP_SNA2,           "SNA" },
 121         { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
 122         { SAP_TI,             "Texas Instruments" },
 123         { SAP_BPDU,           "Spanning Tree BPDU" },
 124         { SAP_RS511,          "EIA RS-511 Manufacturing Message Service" },
 125         { SAP_X25,            "ISO 8208 (X.25 over 802.2)" },
 126         /*
 127          * XXX - setting the group bit of SAP_X25 make 0x7F; is this just
 128          * a group version of that?
 129          */
 130         { 0x7F,               "ISO 802.2" },
 131         { SAP_XNS,            "XNS" },
 132         { SAP_NESTAR,         "Nestar" },
 133         { SAP_PROWAY_ASLM,    "PROWAY (IEC955) Active Station List Maintenance" },
 134         { SAP_ARP,            "ARP" },  /* XXX - hand to "dissect_arp()"? */
 135         { SAP_SNAP,           "SNAP" },
 136         { SAP_VINES1,         "Banyan Vines" },
 137         { SAP_VINES2,         "Banyan Vines" },
 138         { SAP_NETWARE,        "NetWare" },
 139         { SAP_NETBIOS,        "NetBIOS" },
 140         { SAP_IBMNM,          "IBM Net Management" },
 141         { SAP_RPL1,           "Remote Program Load" },
 142         { SAP_UB,             "Ungermann-Bass" },
 143         { SAP_RPL2,           "Remote Program Load" },
 144         { SAP_OSINL,          "ISO Network Layer" },
 145         { SAP_GLOBAL,         "Global LSAP" },
 146         { 0x00,               NULL }
 147 };
 148
 149 static struct sap_info  saps[] = {
 150         { SAP_IP,                       capture_ip },
 151         { SAP_NETWARE,                  capture_ipx },
 152         { SAP_NETBIOS,                  capture_netbios },
 153         { 0x00,                         NULL}
 154 };
 155
 156 /*
 157  * See
 158  *
 159  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 160  *
 161  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 162  */
 163 const value_string oui_vals[] = {
 164         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 165 /*
 166 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 167 */
 168         { OUI_CISCO,       "Cisco" },
 169         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 170         { OUI_BRIDGED,     "Frame Relay or ATM bridged frames" },
 171                                 /* RFC 2427, RFC 2684 */
 172         { OUI_ATM_FORUM,   "ATM Forum" },
 173         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 174         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 175         { 0,               NULL }
 176 };
 177
 178 static capture_func_t *
 179 sap_capture_func(u_char sap) {
 180         int i=0;
 181
 182         /* look for the second record where sap == 0, which should
 183          * be the last record
 184          */
 185         while (saps[i].sap > 0 || i == 0) {
 186                 if (saps[i].sap == sap) {
 187                         return saps[i].capture_func;
 188                 }
 189                 i++;
 190         }
 191         return NULL;
 192 }
 193
 194 void
 195 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
 196
 197         int             is_snap;
 198         guint16         control;
 199         int             llc_header_len;
 200         guint32         oui;
 201         guint16         etype;
 202         capture_func_t  *capture;
 203
 204         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 205                 ld->other++;
 206                 return;
 207         }
 208         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 209         llc_header_len = 2;     /* DSAP + SSAP */
 210
 211         /*
 212          * XXX - the page referred to in the comment above about the
 213          * Command/Response bit also implies that LLC Type 2 always
 214          * uses extended operation, so we don't need to determine
 215          * whether it's basic or extended operation; is that the case?
 216          */
 217         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
 218             TRUE);
 219         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 220         if (is_snap)
 221                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 222         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 223                 ld->other++;
 224                 return;
 225         }
 226
 227         if (is_snap) {
 228                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 229                 if (XDLC_IS_INFORMATION(control)) {
 230                         etype = pntohs(&pd[offset+6]);
 231                         switch (oui) {
 232
 233                         case OUI_ENCAP_ETHER:
 234                         case OUI_APPLE_ATALK:
 235                                 /* No, I have no idea why Apple used
 236                                    one of their own OUIs, rather than
 237                                    OUI_ENCAP_ETHER, and an Ethernet
 238                                    packet type as protocol ID, for
 239                                    AppleTalk data packets - but used
 240                                    OUI_ENCAP_ETHER and an Ethernet
 241                                    packet type for AARP packets. */
 242                                 capture_ethertype(etype, offset+8, pd,
 243                                     ld);
 244                                 break;
 245                         case OUI_CISCO:
 246                                 capture_ethertype(etype,
 247                                                 offset + 8, pd, ld);
 248                                 break;
 249                         default:
 250                                 ld->other++;
 251                                 break;
 252                         }
 253                 }
 254         }
 255         else {
 256                 if (XDLC_IS_INFORMATION(control)) {
 257                         capture = sap_capture_func(pd[offset]);
 258
 259                         /* non-SNAP */
 260                         offset += llc_header_len;
 261
 262                         if (capture) {
 263                                 capture(pd, offset, ld);
 264                         }
 265                         else {
 266                                 ld->other++;
 267                         }
 268                 }
 269         }
 270 }
 271
 272 static void
 273 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 274 {
 275         proto_tree      *llc_tree = NULL;
 276         proto_item      *ti = NULL;
 277         int             is_snap;
 278         guint16         control;
 279         int             llc_header_len;
 280         guint8          dsap, ssap;
 281         tvbuff_t        *next_tvb;
 282
 283         CHECK_DISPLAY_AS_DATA(proto_llc, tvb, pinfo, tree);
 284
 285         pinfo->current_proto = "LLC";
 286
 287         if (check_col(pinfo->fd, COL_PROTOCOL)) {
 288                 col_set_str(pinfo->fd, COL_PROTOCOL, "LLC");
 289         }
 290         if (check_col(pinfo->fd, COL_INFO)) {
 291                 col_clear(pinfo->fd, COL_INFO);
 292         }
 293
 294         dsap = tvb_get_guint8(tvb, 0);
 295         if (tree) {
 296                 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, 0, FALSE);
 297                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 298                 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
 299                         1, dsap & SAP_MASK);
 300                 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
 301                         1, dsap & DSAP_GI_BIT);
 302         } else
 303                 llc_tree = NULL;
 304
 305         ssap = tvb_get_guint8(tvb, 1);
 306         if (tree) {
 307                 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
 308                         1, ssap & SAP_MASK);
 309                 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
 310                         1, ssap & SSAP_CR_BIT);
 311         } else
 312                 llc_tree = NULL;
 313
 314         is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
 315         llc_header_len = 2;     /* DSAP + SSAP */
 316
 317         /*
 318          * XXX - the page referred to in the comment above about the
 319          * Command/Response bit also implies that LLC Type 2 always
 320          * uses extended operation, so we don't need to determine
 321          * whether it's basic or extended operation; is that the case?
 322          */
 323         control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
 324                                 hf_llc_ctrl, ett_llc_ctrl,
 325                                 ssap & SSAP_CR_BIT, TRUE);
 326         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 327         if (is_snap)
 328                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 329
 330         if (tree)
 331                 proto_item_set_len(ti, llc_header_len);
 332
 333         if (is_snap) {
 334                 dissect_snap(tvb, 3, pinfo, tree, llc_tree, control,
 335                     hf_llc_oui, hf_llc_type, hf_llc_pid, 2);
 336         }
 337         else {
 338                 if (check_col(pinfo->fd, COL_INFO)) {
 339                         col_append_fstr(pinfo->fd, COL_INFO,
 340                             "; DSAP %s %s, SSAP %s %s",
 341                             val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
 342                             dsap & DSAP_GI_BIT ?
 343                               "Group" : "Individual",
 344                             val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
 345                             ssap & SSAP_CR_BIT ?
 346                               "Response" : "Command"
 347                         );
 348                 }
 349
 350                 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
 351                 if (XDLC_IS_INFORMATION(control)) {
 352                         /* non-SNAP */
 353                         /* do lookup with the subdissector table */
 354                         if (!dissector_try_port(subdissector_table, dsap,
 355                             next_tvb, pinfo, tree)) {
 356                                 dissect_data(next_tvb, 0, pinfo, tree);
 357                         }
 358                 } else {
 359                         dissect_data(next_tvb, 0, pinfo, tree);
 360                 }
 361         }
 362 }
 363
 364 /*
 365  * Dissect SNAP header; used elsewhere, e.g. in the Frame Relay dissector.
 366  */
 367 void
 368 dissect_snap(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree,
 369     proto_tree *snap_tree, int control, int hf_oui, int hf_type, int hf_pid,
 370     int bridge_pad)
 371 {
 372         guint32         oui;
 373         guint16         etype;
 374         tvbuff_t        *next_tvb;
 375
 376         oui =   tvb_get_ntoh24(tvb, offset);
 377         etype = tvb_get_ntohs(tvb, offset+3);
 378
 379         if (check_col(pinfo->fd, COL_INFO)) {
 380                 col_append_fstr(pinfo->fd, COL_INFO,
 381                     "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
 382                     oui, val_to_str(oui, oui_vals, "Unknown"), etype);
 383         }
 384         if (tree) {
 385                 proto_tree_add_uint(snap_tree, hf_oui, tvb, offset, 3, oui);
 386         }
 387
 388         switch (oui) {
 389
 390         case OUI_ENCAP_ETHER:
 391         case OUI_APPLE_ATALK:
 392                 /* No, I have no idea why Apple used
 393                    one of their own OUIs, rather than
 394                    OUI_ENCAP_ETHER, and an Ethernet
 395                    packet type as protocol ID, for
 396                    AppleTalk data packets - but used
 397                    OUI_ENCAP_ETHER and an Ethernet
 398                    packet type for AARP packets. */
 399                 if (XDLC_IS_INFORMATION(control)) {
 400                         ethertype(etype, tvb, offset+5,
 401                             pinfo, tree, snap_tree, hf_type);
 402                 } else {
 403                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 404                         dissect_data(next_tvb, 0, pinfo, tree);
 405                 }
 406                 break;
 407
 408         case OUI_BRIDGED:
 409                 /*
 410                  * MAC frames bridged over ATM (RFC 2684) or Frame Relay
 411                  * (RFC 2427).
 412                  *
 413                  * We have to figure out how much padding to put
 414                  * into the frame.  We were handed a "bridge_pad"
 415                  * argument which should be 0 for Frame Relay and
 416                  * 2 for ATM; we add to that the amount of padding
 417                  * common to both bridging types.
 418                  */
 419                 if (tree) {
 420                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 421                             etype);
 422                 }
 423
 424                 switch (etype) {
 425
 426                 case BPID_ETH_WITH_FCS:
 427                 case BPID_ETH_WITHOUT_FCS:
 428                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 429                             -1, -1);
 430                         call_dissector(eth_handle, next_tvb, pinfo, tree);
 431                         break;
 432
 433                 case BPID_802_5_WITH_FCS:
 434                 case BPID_802_5_WITHOUT_FCS:
 435                         /*
 436                          * We treat the last padding byte as the Access
 437                          * Control byte, as that's what the Token
 438                          * Ring dissector expects the first byte to
 439                          * be.
 440                          */
 441                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 442                             -1, -1);
 443                         call_dissector(tr_handle, next_tvb, pinfo, tree);
 444                         break;
 445
 446                 case BPID_FDDI_WITH_FCS:
 447                 case BPID_FDDI_WITHOUT_FCS:
 448                         next_tvb = tvb_new_subset(tvb, offset+5+1+bridge_pad,
 449                             -1, -1);
 450                         call_dissector(fddi_handle, next_tvb, pinfo, tree);
 451                         break;
 452
 453                 case BPID_BPDU:
 454                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 455                         call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 456                         break;
 457
 458                 default:
 459                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 460                         dissect_data(next_tvb, 0, pinfo, tree);
 461                         break;
 462                 }
 463                 break;
 464
 465         case OUI_CISCO:
 466                 /* So are all CDP packets LLC packets
 467                    with an OUI of OUI_CISCO and a
 468                    protocol ID of 0x2000, or
 469                    are some of them raw or encapsulated
 470                    Ethernet? */
 471                 if (tree) {
 472                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 473                             etype);
 474                 }
 475                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 476                 if (XDLC_IS_INFORMATION(control)) {
 477                         /* do lookup with the subdissector table */
 478                         /* for future reference, 0x0102 is Cisco DRIP */
 479                         if (!dissector_try_port(cisco_subdissector_table,
 480                             etype, next_tvb, pinfo, tree))
 481                                 dissect_data(next_tvb, 0, pinfo, tree);
 482                 } else
 483                         dissect_data(next_tvb, 0, pinfo, tree);
 484                 break;
 485
 486         case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 487                 if (tree) {
 488                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 489                             etype);
 490                 }
 491                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 492                 call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 493                 break;
 494
 495         default:
 496                 if (tree) {
 497                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 498                             etype);
 499                 }
 500                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 501                 dissect_data(next_tvb, 0, pinfo, tree);
 502                 break;
 503         }
 504 }
 505
 506 void
 507 proto_register_llc(void)
 508 {
 509         static struct true_false_string ig_bit = { "Group", "Individual" };
 510         static struct true_false_string cr_bit = { "Response", "Command" };
 511
 512         static hf_register_info hf[] = {
 513                 { &hf_llc_dsap,
 514                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 515                         VALS(sap_vals), 0x0, "" }},
 516
 517                 { &hf_llc_dsap_ig,
 518                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 519                         &ig_bit, 0x0, "Individual/Group" }},
 520
 521                 { &hf_llc_ssap,
 522                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 523                         VALS(sap_vals), 0x0, "" }},
 524
 525                 { &hf_llc_ssap_cr,
 526                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 527                         &cr_bit, 0x0, "Command/Response" }},
 528
 529                 { &hf_llc_ctrl,
 530                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 531                         NULL, 0x0, "" }},
 532
 533                 /* registered here but handled in ethertype.c */
 534                 { &hf_llc_type,
 535                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 536                         VALS(etype_vals), 0x0, "" }},
 537
 538                 { &hf_llc_oui,
 539                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 540                         VALS(oui_vals), 0x0, ""}},
 541
 542                 { &hf_llc_pid,
 543                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 544                         NULL, 0x0, ""}}
 545         };
 546         static gint *ett[] = {
 547                 &ett_llc,
 548                 &ett_llc_ctrl,
 549         };
 550
 551         proto_llc = proto_register_protocol("Logical-Link Control", "LLC", "llc");
 552         proto_register_field_array(proto_llc, hf, array_length(hf));
 553         proto_register_subtree_array(ett, array_length(ett));
 554
 555 /* subdissector code */
 556         subdissector_table = register_dissector_table("llc.dsap");
 557         cisco_subdissector_table = register_dissector_table("llc.cisco_pid");
 558
 559         register_dissector("llc", dissect_llc, proto_llc);
 560 }
 561
 562 void
 563 proto_reg_handoff_llc(void)
 564 {
 565         /*
 566          * Get handles for the BPDU, Ethernet, FDDI, and Token Ring
 567          * dissectors.
 568          */
 569         bpdu_handle = find_dissector("bpdu");
 570         eth_handle = find_dissector("eth");
 571         fddi_handle = find_dissector("fddi");
 572         tr_handle = find_dissector("tr");
 573
 574         dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, dissect_llc,
 575             proto_llc);
 576 }