packet-llc.c

   1 /* packet-llc.c
   2  * Routines for IEEE 802.2 LLC layer
   3  * Gilbert Ramirez <gram@alumni.rice.edu>
   4  *
   5  * $Id: packet-llc.c,v 1.98 2002/05/29 03:08:01 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@ethereal.com>
   9  * Copyright 1998 Gerald Combs
  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 <glib.h>
  35 #include <epan/packet.h>
  36 #include "oui.h"
  37 #include "xdlc.h"
  38 #include "etypes.h"
  39 #include "llcsaps.h"
  40 #include "bridged_pids.h"
  41 #include "ppptypes.h"
  42 #include "packet-ip.h"
  43 #include "packet-ipx.h"
  44 #include "packet-netbios.h"
  45 #include <epan/sna-utils.h>
  46
  47 #include "packet-llc.h"
  48
  49 #define UDP_PORT_LLC1   12000
  50 #define UDP_PORT_LLC2   12001
  51 #define UDP_PORT_LLC3   12002
  52 #define UDP_PORT_LLC4   12003
  53 #define UDP_PORT_LLC5   12004
  54
  55 static int proto_llc = -1;
  56 static int hf_llc_dsap = -1;
  57 static int hf_llc_ssap = -1;
  58 static int hf_llc_dsap_ig = -1;
  59 static int hf_llc_ssap_cr = -1;
  60 static int hf_llc_ctrl = -1;
  61 static int hf_llc_type = -1;
  62 static int hf_llc_oui = -1;
  63 static int hf_llc_pid = -1;
  64
  65 static gint ett_llc = -1;
  66 static gint ett_llc_ctrl = -1;
  67
  68 static dissector_table_t subdissector_table;
  69 static dissector_table_t cisco_subdissector_table;
  70
  71 static dissector_handle_t bpdu_handle;
  72 static dissector_handle_t eth_handle;
  73 static dissector_handle_t fddi_handle;
  74 static dissector_handle_t tr_handle;
  75 static dissector_handle_t data_handle;
  76
  77 /*
  78  * Group/Individual bit, in the DSAP.
  79  */
  80 #define DSAP_GI_BIT     0x01
  81
  82 /*
  83  * Command/Response bit, in the SSAP.
  84  *
  85  * The low-order bit of the SSAP apparently determines whether this
  86  * is a request or a response.  (RFC 1390, "Transmission of IP and
  87  * ARP over FDDI Networks", says
  88  *
  89  *      Command frames are identified by having the low order
  90  *      bit of the SSAP address reset to zero.  Response frames
  91  *      have the low order bit of the SSAP address set to one.
  92  *
  93  * and a page I've seen seems to imply that's part of 802.2.)
  94  */
  95 #define SSAP_CR_BIT     0x01
  96
  97 /*
  98  * Mask to extrace the SAP number from the DSAP or the SSAP.
  99  */
 100 #define SAP_MASK        0xFE
 101
 102 /*
 103  * These are for SSAP and DSAP, wth last bit always zero.
 104  * XXX - some DSAPs come in separate "individual" and "group" versions,
 105  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
 106  * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
 107  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
 108  */
 109 static const value_string sap_vals[] = {
 110         { SAP_NULL,           "NULL LSAP" },
 111         { SAP_LLC_SLMGMT,     "LLC Sub-Layer Management" },
 112         { SAP_SNA_PATHCTRL,   "SNA Path Control" },
 113         { SAP_IP,             "TCP/IP" },
 114         { SAP_SNA1,           "SNA" },
 115         { SAP_SNA2,           "SNA" },
 116         { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
 117         { SAP_TI,             "Texas Instruments" },
 118         { SAP_BPDU,           "Spanning Tree BPDU" },
 119         { SAP_RS511,          "EIA RS-511 Manufacturing Message Service" },
 120         { SAP_X25,            "ISO 8208 (X.25 over 802.2)" },
 121         /*
 122          * XXX - setting the group bit of SAP_X25 make 0x7F; is this just
 123          * a group version of that?
 124          */
 125         { 0x7F,               "ISO 802.2" },
 126         { SAP_XNS,            "XNS" },
 127         { SAP_NESTAR,         "Nestar" },
 128         { SAP_PROWAY_ASLM,    "PROWAY (IEC955) Active Station List Maintenance" },
 129         { SAP_ARP,            "ARP" },  /* XXX - hand to "dissect_arp()"? */
 130         { SAP_SNAP,           "SNAP" },
 131         { SAP_VINES1,         "Banyan Vines" },
 132         { SAP_VINES2,         "Banyan Vines" },
 133         { SAP_NETWARE,        "NetWare" },
 134         { SAP_NETBIOS,        "NetBIOS" },
 135         { SAP_IBMNM,          "IBM Net Management" },
 136         { SAP_RPL1,           "Remote Program Load" },
 137         { SAP_UB,             "Ungermann-Bass" },
 138         { SAP_RPL2,           "Remote Program Load" },
 139         { SAP_OSINL,          "ISO Network Layer" },
 140         { SAP_GLOBAL,         "Global LSAP" },
 141         { 0x00,               NULL }
 142 };
 143
 144 /*
 145  * See
 146  *
 147  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 148  *
 149  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 150  */
 151 const value_string oui_vals[] = {
 152         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 153 /*
 154 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 155 */
 156         { OUI_CISCO,       "Cisco" },
 157         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 158         { OUI_BRIDGED,     "Frame Relay or ATM bridged frames" },
 159                                 /* RFC 2427, RFC 2684 */
 160         { OUI_ATM_FORUM,   "ATM Forum" },
 161         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 162         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 163         { 0,               NULL }
 164 };
 165
 166 void
 167 capture_llc(const u_char *pd, int offset, int len, packet_counts *ld) {
 168
 169         int             is_snap;
 170         guint16         control;
 171         int             llc_header_len;
 172         guint32         oui;
 173         guint16         etype;
 174
 175         if (!BYTES_ARE_IN_FRAME(offset, len, 2)) {
 176                 ld->other++;
 177                 return;
 178         }
 179         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 180         llc_header_len = 2;     /* DSAP + SSAP */
 181
 182         /*
 183          * XXX - the page referred to in the comment above about the
 184          * Command/Response bit also implies that LLC Type 2 always
 185          * uses extended operation, so we don't need to determine
 186          * whether it's basic or extended operation; is that the case?
 187          */
 188         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT);
 189         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 190         if (is_snap)
 191                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 192         if (!BYTES_ARE_IN_FRAME(offset, len, llc_header_len)) {
 193                 ld->other++;
 194                 return;
 195         }
 196
 197         if (is_snap) {
 198                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 199                 if (XDLC_IS_INFORMATION(control)) {
 200                         etype = pntohs(&pd[offset+6]);
 201                         switch (oui) {
 202
 203                         case OUI_ENCAP_ETHER:
 204                         case OUI_CISCO_90:
 205                         case OUI_APPLE_ATALK:
 206                                 /* No, I have no idea why Apple used
 207                                    one of their own OUIs, rather than
 208                                    OUI_ENCAP_ETHER, and an Ethernet
 209                                    packet type as protocol ID, for
 210                                    AppleTalk data packets - but used
 211                                    OUI_ENCAP_ETHER and an Ethernet
 212                                    packet type for AARP packets. */
 213                                 capture_ethertype(etype, pd, offset+8, len,
 214                                     ld);
 215                                 break;
 216                         case OUI_CISCO:
 217                                 capture_ethertype(etype, pd, offset + 8, len,
 218                                     ld);
 219                                 break;
 220                         default:
 221                                 ld->other++;
 222                                 break;
 223                         }
 224                 }
 225         }
 226         else {
 227                 /* non-SNAP */
 228                 if (XDLC_IS_INFORMATION(control)) {
 229                         switch (pd[offset]) {
 230
 231                         case SAP_IP:
 232                                 capture_ip(pd, offset + llc_header_len, len,
 233                                     ld);
 234                                 break;
 235
 236                         case SAP_NETWARE:
 237                                 capture_ipx(ld);
 238                                 break;
 239
 240                         case SAP_NETBIOS:
 241                                 capture_netbios(ld);
 242                                 break;
 243
 244                         default:
 245                                 ld->other++;
 246                                 break;
 247                         }
 248                 }
 249         }
 250 }
 251
 252 static void
 253 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 254 {
 255         proto_tree      *llc_tree = NULL;
 256         proto_item      *ti = NULL;
 257         int             is_snap;
 258         guint16         control;
 259         int             llc_header_len;
 260         guint8          dsap, ssap;
 261         tvbuff_t        *next_tvb;
 262
 263         if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 264                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "LLC");
 265         }
 266         if (check_col(pinfo->cinfo, COL_INFO)) {
 267                 col_clear(pinfo->cinfo, COL_INFO);
 268         }
 269
 270         dsap = tvb_get_guint8(tvb, 0);
 271         if (tree) {
 272                 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, -1, FALSE);
 273                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 274                 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
 275                         1, dsap & SAP_MASK);
 276                 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
 277                         1, dsap & DSAP_GI_BIT);
 278         } else
 279                 llc_tree = NULL;
 280
 281         ssap = tvb_get_guint8(tvb, 1);
 282         if (tree) {
 283                 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
 284                         1, ssap & SAP_MASK);
 285                 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
 286                         1, ssap & SSAP_CR_BIT);
 287         } else
 288                 llc_tree = NULL;
 289
 290         is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
 291         llc_header_len = 2;     /* DSAP + SSAP */
 292
 293         /*
 294          * XXX - the page referred to in the comment above about the
 295          * Command/Response bit also implies that LLC Type 2 always
 296          * uses extended operation, so we don't need to determine
 297          * whether it's basic or extended operation; is that the case?
 298          */
 299         control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
 300                                 hf_llc_ctrl, ett_llc_ctrl,
 301                                 ssap & SSAP_CR_BIT, TRUE);
 302         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 303         if (is_snap)
 304                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 305
 306         if (tree)
 307                 proto_item_set_len(ti, llc_header_len);
 308
 309         if (is_snap) {
 310                 dissect_snap(tvb, 3, pinfo, tree, llc_tree, control,
 311                     hf_llc_oui, hf_llc_type, hf_llc_pid, 2);
 312         }
 313         else {
 314                 if (check_col(pinfo->cinfo, COL_INFO)) {
 315                         col_append_fstr(pinfo->cinfo, COL_INFO,
 316                             "; DSAP %s %s, SSAP %s %s",
 317                             val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
 318                             dsap & DSAP_GI_BIT ?
 319                               "Group" : "Individual",
 320                             val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
 321                             ssap & SSAP_CR_BIT ?
 322                               "Response" : "Command"
 323                         );
 324                 }
 325
 326                 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
 327                 if (XDLC_IS_INFORMATION(control)) {
 328                         /* non-SNAP */
 329                         /* do lookup with the subdissector table */
 330                         if (!dissector_try_port(subdissector_table, dsap,
 331                             next_tvb, pinfo, tree)) {
 332                                 call_dissector(data_handle,next_tvb, pinfo, tree);
 333                         }
 334                 } else {
 335                         call_dissector(data_handle,next_tvb, pinfo, tree);
 336                 }
 337         }
 338 }
 339
 340 /*
 341  * Dissect SNAP header; used elsewhere, e.g. in the Frame Relay dissector.
 342  */
 343 void
 344 dissect_snap(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree,
 345     proto_tree *snap_tree, int control, int hf_oui, int hf_type, int hf_pid,
 346     int bridge_pad)
 347 {
 348         guint32         oui;
 349         guint16         etype;
 350         tvbuff_t        *next_tvb;
 351
 352         oui =   tvb_get_ntoh24(tvb, offset);
 353         etype = tvb_get_ntohs(tvb, offset+3);
 354
 355         if (check_col(pinfo->cinfo, COL_INFO)) {
 356                 col_append_fstr(pinfo->cinfo, COL_INFO,
 357                     "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
 358                     oui, val_to_str(oui, oui_vals, "Unknown"), etype);
 359         }
 360         if (tree) {
 361                 proto_tree_add_uint(snap_tree, hf_oui, tvb, offset, 3, oui);
 362         }
 363
 364         switch (oui) {
 365
 366         case OUI_ENCAP_ETHER:
 367         case OUI_CISCO_90:
 368         case OUI_APPLE_ATALK:
 369                 /* No, I have no idea why Apple used
 370                    one of their own OUIs, rather than
 371                    OUI_ENCAP_ETHER, and an Ethernet
 372                    packet type as protocol ID, for
 373                    AppleTalk data packets - but used
 374                    OUI_ENCAP_ETHER and an Ethernet
 375                    packet type for AARP packets. */
 376                 if (XDLC_IS_INFORMATION(control)) {
 377                         ethertype(etype, tvb, offset+5,
 378                             pinfo, tree, snap_tree, hf_type, -1);
 379                 } else {
 380                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 381                         call_dissector(data_handle,next_tvb, pinfo, tree);
 382                 }
 383                 break;
 384
 385         case OUI_BRIDGED:
 386                 /*
 387                  * MAC frames bridged over ATM (RFC 2684) or Frame Relay
 388                  * (RFC 2427).
 389                  *
 390                  * We have to figure out how much padding to put
 391                  * into the frame.  We were handed a "bridge_pad"
 392                  * argument which should be 0 for Frame Relay and
 393                  * 2 for ATM; we add to that the amount of padding
 394                  * common to both bridging types.
 395                  */
 396                 if (tree) {
 397                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 398                             etype);
 399                 }
 400
 401                 switch (etype) {
 402
 403                 case BPID_ETH_WITH_FCS:
 404                 case BPID_ETH_WITHOUT_FCS:
 405                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 406                             -1, -1);
 407                         call_dissector(eth_handle, next_tvb, pinfo, tree);
 408                         break;
 409
 410                 case BPID_802_5_WITH_FCS:
 411                 case BPID_802_5_WITHOUT_FCS:
 412                         /*
 413                          * We treat the last padding byte as the Access
 414                          * Control byte, as that's what the Token
 415                          * Ring dissector expects the first byte to
 416                          * be.
 417                          */
 418                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 419                             -1, -1);
 420                         call_dissector(tr_handle, next_tvb, pinfo, tree);
 421                         break;
 422
 423                 case BPID_FDDI_WITH_FCS:
 424                 case BPID_FDDI_WITHOUT_FCS:
 425                         next_tvb = tvb_new_subset(tvb, offset+5+1+bridge_pad,
 426                             -1, -1);
 427                         call_dissector(fddi_handle, next_tvb, pinfo, tree);
 428                         break;
 429
 430                 case BPID_BPDU:
 431                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 432                         call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 433                         break;
 434
 435                 default:
 436                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 437                         call_dissector(data_handle,next_tvb, pinfo, tree);
 438                         break;
 439                 }
 440                 break;
 441
 442         case OUI_CISCO:
 443                 /* So are all CDP packets LLC packets
 444                    with an OUI of OUI_CISCO and a
 445                    protocol ID of 0x2000, or
 446                    are some of them raw or encapsulated
 447                    Ethernet? */
 448                 if (tree) {
 449                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 450                             etype);
 451                 }
 452                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 453                 if (XDLC_IS_INFORMATION(control)) {
 454                         /* do lookup with the subdissector table */
 455                         /* for future reference, 0x0102 is Cisco DRIP */
 456                         if (!dissector_try_port(cisco_subdissector_table,
 457                             etype, next_tvb, pinfo, tree))
 458                                 call_dissector(data_handle,next_tvb, pinfo, tree);
 459                 } else
 460                         call_dissector(data_handle,next_tvb, pinfo, tree);
 461                 break;
 462
 463         case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 464                 if (tree) {
 465                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 466                             etype);
 467                 }
 468                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 469                 call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 470                 break;
 471
 472         default:
 473                 if (tree) {
 474                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 475                             etype);
 476                 }
 477                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 478                 call_dissector(data_handle,next_tvb, pinfo, tree);
 479                 break;
 480         }
 481 }
 482
 483 void
 484 proto_register_llc(void)
 485 {
 486         static struct true_false_string ig_bit = { "Group", "Individual" };
 487         static struct true_false_string cr_bit = { "Response", "Command" };
 488
 489         static hf_register_info hf[] = {
 490                 { &hf_llc_dsap,
 491                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 492                         VALS(sap_vals), 0x0, "", HFILL }},
 493
 494                 { &hf_llc_dsap_ig,
 495                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 496                         &ig_bit, 0x0, "Individual/Group", HFILL }},
 497
 498                 { &hf_llc_ssap,
 499                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 500                         VALS(sap_vals), 0x0, "", HFILL }},
 501
 502                 { &hf_llc_ssap_cr,
 503                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 504                         &cr_bit, 0x0, "Command/Response", HFILL }},
 505
 506                 { &hf_llc_ctrl,
 507                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 508                         NULL, 0x0, "", HFILL }},
 509
 510                 /* registered here but handled in ethertype.c */
 511                 { &hf_llc_type,
 512                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 513                         VALS(etype_vals), 0x0, "", HFILL }},
 514
 515                 { &hf_llc_oui,
 516                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 517                         VALS(oui_vals), 0x0, "", HFILL }},
 518
 519                 { &hf_llc_pid,
 520                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 521                         NULL, 0x0, "", HFILL }}
 522         };
 523         static gint *ett[] = {
 524                 &ett_llc,
 525                 &ett_llc_ctrl,
 526         };
 527
 528         proto_llc = proto_register_protocol("Logical-Link Control", "LLC", "llc");
 529         proto_register_field_array(proto_llc, hf, array_length(hf));
 530         proto_register_subtree_array(ett, array_length(ett));
 531
 532 /* subdissector code */
 533         subdissector_table = register_dissector_table("llc.dsap",
 534           "LLC SAP", FT_UINT8, BASE_HEX);
 535         cisco_subdissector_table = register_dissector_table("llc.cisco_pid",
 536           "Cisco OUI PID", FT_UINT16, BASE_HEX);
 537
 538         register_dissector("llc", dissect_llc, proto_llc);
 539 }
 540
 541 void
 542 proto_reg_handoff_llc(void)
 543 {
 544         dissector_handle_t llc_handle;
 545
 546         /*
 547          * Get handles for the BPDU, Ethernet, FDDI, and Token Ring
 548          * dissectors.
 549          */
 550         bpdu_handle = find_dissector("bpdu");
 551         eth_handle = find_dissector("eth");
 552         fddi_handle = find_dissector("fddi");
 553         tr_handle = find_dissector("tr");
 554         data_handle = find_dissector("data");
 555
 556         llc_handle = find_dissector("llc");
 557         dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, llc_handle);
 558         /* RFC 2043 */
 559         dissector_add("ppp.protocol", PPP_LLC, llc_handle);
 560         /* RFC 2353 */
 561         dissector_add("udp.port", UDP_PORT_LLC1, llc_handle);
 562         dissector_add("udp.port", UDP_PORT_LLC2, llc_handle);
 563         dissector_add("udp.port", UDP_PORT_LLC3, llc_handle);
 564         dissector_add("udp.port", UDP_PORT_LLC4, llc_handle);
 565         dissector_add("udp.port", UDP_PORT_LLC5, llc_handle);
 566 }