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 1.100 2002/08/28 21:00:20 jmayer 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 #include <glib.h>
  31 #include <epan/packet.h>
  32 #include "oui.h"
  33 #include "xdlc.h"
  34 #include "etypes.h"
  35 #include "llcsaps.h"
  36 #include "bridged_pids.h"
  37 #include "ppptypes.h"
  38 #include "packet-ip.h"
  39 #include "packet-ipx.h"
  40 #include "packet-netbios.h"
  41 #include <epan/sna-utils.h>
  42
  43 #include "packet-llc.h"
  44
  45 #define UDP_PORT_LLC1   12000
  46 #define UDP_PORT_LLC2   12001
  47 #define UDP_PORT_LLC3   12002
  48 #define UDP_PORT_LLC4   12003
  49 #define UDP_PORT_LLC5   12004
  50
  51 static int proto_llc = -1;
  52 static int hf_llc_dsap = -1;
  53 static int hf_llc_ssap = -1;
  54 static int hf_llc_dsap_ig = -1;
  55 static int hf_llc_ssap_cr = -1;
  56 static int hf_llc_ctrl = -1;
  57 static int hf_llc_type = -1;
  58 static int hf_llc_oui = -1;
  59 static int hf_llc_pid = -1;
  60
  61 static gint ett_llc = -1;
  62 static gint ett_llc_ctrl = -1;
  63
  64 static dissector_table_t subdissector_table;
  65 static dissector_table_t cisco_subdissector_table;
  66
  67 static dissector_handle_t bpdu_handle;
  68 static dissector_handle_t eth_handle;
  69 static dissector_handle_t fddi_handle;
  70 static dissector_handle_t tr_handle;
  71 static dissector_handle_t data_handle;
  72
  73 /*
  74  * Group/Individual bit, in the DSAP.
  75  */
  76 #define DSAP_GI_BIT     0x01
  77
  78 /*
  79  * Command/Response bit, in the SSAP.
  80  *
  81  * The low-order bit of the SSAP apparently determines whether this
  82  * is a request or a response.  (RFC 1390, "Transmission of IP and
  83  * ARP over FDDI Networks", says
  84  *
  85  *      Command frames are identified by having the low order
  86  *      bit of the SSAP address reset to zero.  Response frames
  87  *      have the low order bit of the SSAP address set to one.
  88  *
  89  * and a page I've seen seems to imply that's part of 802.2.)
  90  */
  91 #define SSAP_CR_BIT     0x01
  92
  93 /*
  94  * Mask to extrace the SAP number from the DSAP or the SSAP.
  95  */
  96 #define SAP_MASK        0xFE
  97
  98 /*
  99  * These are for SSAP and DSAP, wth last bit always zero.
 100  * XXX - some DSAPs come in separate "individual" and "group" versions,
 101  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
 102  * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
 103  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
 104  */
 105 static const value_string sap_vals[] = {
 106         { SAP_NULL,           "NULL LSAP" },
 107         { SAP_LLC_SLMGMT,     "LLC Sub-Layer Management" },
 108         { SAP_SNA_PATHCTRL,   "SNA Path Control" },
 109         { SAP_IP,             "TCP/IP" },
 110         { SAP_SNA1,           "SNA" },
 111         { SAP_SNA2,           "SNA" },
 112         { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
 113         { SAP_TI,             "Texas Instruments" },
 114         { SAP_BPDU,           "Spanning Tree BPDU" },
 115         { SAP_RS511,          "EIA RS-511 Manufacturing Message Service" },
 116         { SAP_X25,            "ISO 8208 (X.25 over 802.2)" },
 117         /*
 118          * XXX - setting the group bit of SAP_X25 make 0x7F; is this just
 119          * a group version of that?
 120          */
 121         { 0x7F,               "ISO 802.2" },
 122         { SAP_XNS,            "XNS" },
 123         { SAP_NESTAR,         "Nestar" },
 124         { SAP_PROWAY_ASLM,    "PROWAY (IEC955) Active Station List Maintenance" },
 125         { SAP_ARP,            "ARP" },  /* XXX - hand to "dissect_arp()"? */
 126         { SAP_SNAP,           "SNAP" },
 127         { SAP_VINES1,         "Banyan Vines" },
 128         { SAP_VINES2,         "Banyan Vines" },
 129         { SAP_NETWARE,        "NetWare" },
 130         { SAP_NETBIOS,        "NetBIOS" },
 131         { SAP_IBMNM,          "IBM Net Management" },
 132         { SAP_RPL1,           "Remote Program Load" },
 133         { SAP_UB,             "Ungermann-Bass" },
 134         { SAP_RPL2,           "Remote Program Load" },
 135         { SAP_OSINL,          "ISO Network Layer" },
 136         { SAP_GLOBAL,         "Global LSAP" },
 137         { 0x00,               NULL }
 138 };
 139
 140 /*
 141  * See
 142  *
 143  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 144  *
 145  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 146  */
 147 const value_string oui_vals[] = {
 148         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 149 /*
 150 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 151 */
 152         { OUI_CISCO,       "Cisco" },
 153         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 154         { OUI_BRIDGED,     "Frame Relay or ATM bridged frames" },
 155                                 /* RFC 2427, RFC 2684 */
 156         { OUI_ATM_FORUM,   "ATM Forum" },
 157         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 158         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 159         { 0,               NULL }
 160 };
 161
 162 void
 163 capture_llc(const guchar *pd, int offset, int len, packet_counts *ld) {
 164
 165         int             is_snap;
 166         guint16         control;
 167         int             llc_header_len;
 168         guint32         oui;
 169         guint16         etype;
 170
 171         if (!BYTES_ARE_IN_FRAME(offset, len, 2)) {
 172                 ld->other++;
 173                 return;
 174         }
 175         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 176         llc_header_len = 2;     /* DSAP + SSAP */
 177
 178         /*
 179          * XXX - the page referred to in the comment above about the
 180          * Command/Response bit also implies that LLC Type 2 always
 181          * uses extended operation, so we don't need to determine
 182          * whether it's basic or extended operation; is that the case?
 183          */
 184         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT);
 185         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 186         if (is_snap)
 187                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 188         if (!BYTES_ARE_IN_FRAME(offset, len, llc_header_len)) {
 189                 ld->other++;
 190                 return;
 191         }
 192
 193         if (is_snap) {
 194                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 195                 if (XDLC_IS_INFORMATION(control)) {
 196                         etype = pntohs(&pd[offset+6]);
 197                         switch (oui) {
 198
 199                         case OUI_ENCAP_ETHER:
 200                         case OUI_CISCO_90:
 201                         case OUI_APPLE_ATALK:
 202                                 /* No, I have no idea why Apple used
 203                                    one of their own OUIs, rather than
 204                                    OUI_ENCAP_ETHER, and an Ethernet
 205                                    packet type as protocol ID, for
 206                                    AppleTalk data packets - but used
 207                                    OUI_ENCAP_ETHER and an Ethernet
 208                                    packet type for AARP packets. */
 209                                 capture_ethertype(etype, pd, offset+8, len,
 210                                     ld);
 211                                 break;
 212                         case OUI_CISCO:
 213                                 capture_ethertype(etype, pd, offset + 8, len,
 214                                     ld);
 215                                 break;
 216                         default:
 217                                 ld->other++;
 218                                 break;
 219                         }
 220                 }
 221         }
 222         else {
 223                 /* non-SNAP */
 224                 if (XDLC_IS_INFORMATION(control)) {
 225                         switch (pd[offset]) {
 226
 227                         case SAP_IP:
 228                                 capture_ip(pd, offset + llc_header_len, len,
 229                                     ld);
 230                                 break;
 231
 232                         case SAP_NETWARE:
 233                                 capture_ipx(ld);
 234                                 break;
 235
 236                         case SAP_NETBIOS:
 237                                 capture_netbios(ld);
 238                                 break;
 239
 240                         default:
 241                                 ld->other++;
 242                                 break;
 243                         }
 244                 }
 245         }
 246 }
 247
 248 static void
 249 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 250 {
 251         proto_tree      *llc_tree = NULL;
 252         proto_item      *ti = NULL;
 253         int             is_snap;
 254         guint16         control;
 255         int             llc_header_len;
 256         guint8          dsap, ssap;
 257         tvbuff_t        *next_tvb;
 258
 259         if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 260                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "LLC");
 261         }
 262         if (check_col(pinfo->cinfo, COL_INFO)) {
 263                 col_clear(pinfo->cinfo, COL_INFO);
 264         }
 265
 266         dsap = tvb_get_guint8(tvb, 0);
 267         if (tree) {
 268                 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, -1, FALSE);
 269                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 270                 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
 271                         1, dsap & SAP_MASK);
 272                 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
 273                         1, dsap & DSAP_GI_BIT);
 274         } else
 275                 llc_tree = NULL;
 276
 277         ssap = tvb_get_guint8(tvb, 1);
 278         if (tree) {
 279                 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
 280                         1, ssap & SAP_MASK);
 281                 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
 282                         1, ssap & SSAP_CR_BIT);
 283         } else
 284                 llc_tree = NULL;
 285
 286         is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
 287         llc_header_len = 2;     /* DSAP + SSAP */
 288
 289         /*
 290          * XXX - the page referred to in the comment above about the
 291          * Command/Response bit also implies that LLC Type 2 always
 292          * uses extended operation, so we don't need to determine
 293          * whether it's basic or extended operation; is that the case?
 294          */
 295         control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
 296                                 hf_llc_ctrl, ett_llc_ctrl,
 297                                 ssap & SSAP_CR_BIT, TRUE);
 298         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 299         if (is_snap)
 300                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 301
 302         if (tree)
 303                 proto_item_set_len(ti, llc_header_len);
 304
 305         if (is_snap) {
 306                 dissect_snap(tvb, 3, pinfo, tree, llc_tree, control,
 307                     hf_llc_oui, hf_llc_type, hf_llc_pid, 2);
 308         }
 309         else {
 310                 if (check_col(pinfo->cinfo, COL_INFO)) {
 311                         col_append_fstr(pinfo->cinfo, COL_INFO,
 312                             "; DSAP %s %s, SSAP %s %s",
 313                             val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
 314                             dsap & DSAP_GI_BIT ?
 315                               "Group" : "Individual",
 316                             val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
 317                             ssap & SSAP_CR_BIT ?
 318                               "Response" : "Command"
 319                         );
 320                 }
 321
 322                 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
 323                 if (XDLC_IS_INFORMATION(control)) {
 324                         /* non-SNAP */
 325                         /* do lookup with the subdissector table */
 326                         if (!dissector_try_port(subdissector_table, dsap,
 327                             next_tvb, pinfo, tree)) {
 328                                 call_dissector(data_handle,next_tvb, pinfo, tree);
 329                         }
 330                 } else {
 331                         call_dissector(data_handle,next_tvb, pinfo, tree);
 332                 }
 333         }
 334 }
 335
 336 /*
 337  * Dissect SNAP header; used elsewhere, e.g. in the Frame Relay dissector.
 338  */
 339 void
 340 dissect_snap(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree,
 341     proto_tree *snap_tree, int control, int hf_oui, int hf_type, int hf_pid,
 342     int bridge_pad)
 343 {
 344         guint32         oui;
 345         guint16         etype;
 346         tvbuff_t        *next_tvb;
 347
 348         oui =   tvb_get_ntoh24(tvb, offset);
 349         etype = tvb_get_ntohs(tvb, offset+3);
 350
 351         if (check_col(pinfo->cinfo, COL_INFO)) {
 352                 col_append_fstr(pinfo->cinfo, COL_INFO,
 353                     "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
 354                     oui, val_to_str(oui, oui_vals, "Unknown"), etype);
 355         }
 356         if (tree) {
 357                 proto_tree_add_uint(snap_tree, hf_oui, tvb, offset, 3, oui);
 358         }
 359
 360         switch (oui) {
 361
 362         case OUI_ENCAP_ETHER:
 363         case OUI_CISCO_90:
 364         case OUI_APPLE_ATALK:
 365                 /* No, I have no idea why Apple used
 366                    one of their own OUIs, rather than
 367                    OUI_ENCAP_ETHER, and an Ethernet
 368                    packet type as protocol ID, for
 369                    AppleTalk data packets - but used
 370                    OUI_ENCAP_ETHER and an Ethernet
 371                    packet type for AARP packets. */
 372                 if (XDLC_IS_INFORMATION(control)) {
 373                         ethertype(etype, tvb, offset+5,
 374                             pinfo, tree, snap_tree, hf_type, -1);
 375                 } else {
 376                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 377                         call_dissector(data_handle,next_tvb, pinfo, tree);
 378                 }
 379                 break;
 380
 381         case OUI_BRIDGED:
 382                 /*
 383                  * MAC frames bridged over ATM (RFC 2684) or Frame Relay
 384                  * (RFC 2427).
 385                  *
 386                  * We have to figure out how much padding to put
 387                  * into the frame.  We were handed a "bridge_pad"
 388                  * argument which should be 0 for Frame Relay and
 389                  * 2 for ATM; we add to that the amount of padding
 390                  * common to both bridging types.
 391                  */
 392                 if (tree) {
 393                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 394                             etype);
 395                 }
 396
 397                 switch (etype) {
 398
 399                 case BPID_ETH_WITH_FCS:
 400                 case BPID_ETH_WITHOUT_FCS:
 401                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 402                             -1, -1);
 403                         call_dissector(eth_handle, next_tvb, pinfo, tree);
 404                         break;
 405
 406                 case BPID_802_5_WITH_FCS:
 407                 case BPID_802_5_WITHOUT_FCS:
 408                         /*
 409                          * We treat the last padding byte as the Access
 410                          * Control byte, as that's what the Token
 411                          * Ring dissector expects the first byte to
 412                          * be.
 413                          */
 414                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 415                             -1, -1);
 416                         call_dissector(tr_handle, next_tvb, pinfo, tree);
 417                         break;
 418
 419                 case BPID_FDDI_WITH_FCS:
 420                 case BPID_FDDI_WITHOUT_FCS:
 421                         next_tvb = tvb_new_subset(tvb, offset+5+1+bridge_pad,
 422                             -1, -1);
 423                         call_dissector(fddi_handle, next_tvb, pinfo, tree);
 424                         break;
 425
 426                 case BPID_BPDU:
 427                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 428                         call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 429                         break;
 430
 431                 default:
 432                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 433                         call_dissector(data_handle,next_tvb, pinfo, tree);
 434                         break;
 435                 }
 436                 break;
 437
 438         case OUI_CISCO:
 439                 /* So are all CDP packets LLC packets
 440                    with an OUI of OUI_CISCO and a
 441                    protocol ID of 0x2000, or
 442                    are some of them raw or encapsulated
 443                    Ethernet? */
 444                 if (tree) {
 445                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 446                             etype);
 447                 }
 448                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 449                 if (XDLC_IS_INFORMATION(control)) {
 450                         /* do lookup with the subdissector table */
 451                         /* for future reference, 0x0102 is Cisco DRIP */
 452                         if (!dissector_try_port(cisco_subdissector_table,
 453                             etype, next_tvb, pinfo, tree))
 454                                 call_dissector(data_handle,next_tvb, pinfo, tree);
 455                 } else
 456                         call_dissector(data_handle,next_tvb, pinfo, tree);
 457                 break;
 458
 459         case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 460                 if (tree) {
 461                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 462                             etype);
 463                 }
 464                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 465                 call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 466                 break;
 467
 468         default:
 469                 if (tree) {
 470                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 471                             etype);
 472                 }
 473                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 474                 call_dissector(data_handle,next_tvb, pinfo, tree);
 475                 break;
 476         }
 477 }
 478
 479 void
 480 proto_register_llc(void)
 481 {
 482         static struct true_false_string ig_bit = { "Group", "Individual" };
 483         static struct true_false_string cr_bit = { "Response", "Command" };
 484
 485         static hf_register_info hf[] = {
 486                 { &hf_llc_dsap,
 487                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 488                         VALS(sap_vals), 0x0, "", HFILL }},
 489
 490                 { &hf_llc_dsap_ig,
 491                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 492                         &ig_bit, 0x0, "Individual/Group", HFILL }},
 493
 494                 { &hf_llc_ssap,
 495                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 496                         VALS(sap_vals), 0x0, "", HFILL }},
 497
 498                 { &hf_llc_ssap_cr,
 499                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 500                         &cr_bit, 0x0, "Command/Response", HFILL }},
 501
 502                 { &hf_llc_ctrl,
 503                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 504                         NULL, 0x0, "", HFILL }},
 505
 506                 /* registered here but handled in ethertype.c */
 507                 { &hf_llc_type,
 508                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 509                         VALS(etype_vals), 0x0, "", HFILL }},
 510
 511                 { &hf_llc_oui,
 512                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 513                         VALS(oui_vals), 0x0, "", HFILL }},
 514
 515                 { &hf_llc_pid,
 516                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 517                         NULL, 0x0, "", HFILL }}
 518         };
 519         static gint *ett[] = {
 520                 &ett_llc,
 521                 &ett_llc_ctrl,
 522         };
 523
 524         proto_llc = proto_register_protocol("Logical-Link Control", "LLC", "llc");
 525         proto_register_field_array(proto_llc, hf, array_length(hf));
 526         proto_register_subtree_array(ett, array_length(ett));
 527
 528 /* subdissector code */
 529         subdissector_table = register_dissector_table("llc.dsap",
 530           "LLC SAP", FT_UINT8, BASE_HEX);
 531         cisco_subdissector_table = register_dissector_table("llc.cisco_pid",
 532           "Cisco OUI PID", FT_UINT16, BASE_HEX);
 533
 534         register_dissector("llc", dissect_llc, proto_llc);
 535 }
 536
 537 void
 538 proto_reg_handoff_llc(void)
 539 {
 540         dissector_handle_t llc_handle;
 541
 542         /*
 543          * Get handles for the BPDU, Ethernet, FDDI, and Token Ring
 544          * dissectors.
 545          */
 546         bpdu_handle = find_dissector("bpdu");
 547         eth_handle = find_dissector("eth");
 548         fddi_handle = find_dissector("fddi");
 549         tr_handle = find_dissector("tr");
 550         data_handle = find_dissector("data");
 551
 552         llc_handle = find_dissector("llc");
 553         dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, llc_handle);
 554         /* RFC 2043 */
 555         dissector_add("ppp.protocol", PPP_LLC, llc_handle);
 556         /* RFC 2353 */
 557         dissector_add("udp.port", UDP_PORT_LLC1, llc_handle);
 558         dissector_add("udp.port", UDP_PORT_LLC2, llc_handle);
 559         dissector_add("udp.port", UDP_PORT_LLC3, llc_handle);
 560         dissector_add("udp.port", UDP_PORT_LLC4, llc_handle);
 561         dissector_add("udp.port", UDP_PORT_LLC5, llc_handle);
 562 }