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 1.96 2002/03/31 21:09:00 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 "packet-ip.h"
  42 #include "packet-ipx.h"
  43 #include "packet-netbios.h"
  44 #include <epan/sna-utils.h>
  45
  46 #include "packet-llc.h"
  47
  48 static int proto_llc = -1;
  49 static int hf_llc_dsap = -1;
  50 static int hf_llc_ssap = -1;
  51 static int hf_llc_dsap_ig = -1;
  52 static int hf_llc_ssap_cr = -1;
  53 static int hf_llc_ctrl = -1;
  54 static int hf_llc_type = -1;
  55 static int hf_llc_oui = -1;
  56 static int hf_llc_pid = -1;
  57
  58 static gint ett_llc = -1;
  59 static gint ett_llc_ctrl = -1;
  60
  61 static dissector_table_t subdissector_table;
  62 static dissector_table_t cisco_subdissector_table;
  63
  64 static dissector_handle_t bpdu_handle;
  65 static dissector_handle_t eth_handle;
  66 static dissector_handle_t fddi_handle;
  67 static dissector_handle_t tr_handle;
  68 static dissector_handle_t data_handle;
  69
  70 typedef void (capture_func_t)(const u_char *, int, int, packet_counts *);
  71
  72 /* The SAP info is split into two tables, one value_string table and one
  73  * table of sap_info. This is so that the value_string can be used in the
  74  * header field registration.
  75  */
  76 struct sap_info {
  77         guint8  sap;
  78         capture_func_t *capture_func;
  79 };
  80
  81 /*
  82  * Group/Individual bit, in the DSAP.
  83  */
  84 #define DSAP_GI_BIT     0x01
  85
  86 /*
  87  * Command/Response bit, in the SSAP.
  88  *
  89  * The low-order bit of the SSAP apparently determines whether this
  90  * is a request or a response.  (RFC 1390, "Transmission of IP and
  91  * ARP over FDDI Networks", says
  92  *
  93  *      Command frames are identified by having the low order
  94  *      bit of the SSAP address reset to zero.  Response frames
  95  *      have the low order bit of the SSAP address set to one.
  96  *
  97  * and a page I've seen seems to imply that's part of 802.2.)
  98  */
  99 #define SSAP_CR_BIT     0x01
 100
 101 /*
 102  * Mask to extrace the SAP number from the DSAP or the SSAP.
 103  */
 104 #define SAP_MASK        0xFE
 105
 106 /*
 107  * These are for SSAP and DSAP, wth last bit always zero.
 108  * XXX - some DSAPs come in separate "individual" and "group" versions,
 109  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
 110  * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
 111  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
 112  */
 113 static const value_string sap_vals[] = {
 114         { SAP_NULL,           "NULL LSAP" },
 115         { SAP_LLC_SLMGMT,     "LLC Sub-Layer Management" },
 116         { SAP_SNA_PATHCTRL,   "SNA Path Control" },
 117         { SAP_IP,             "TCP/IP" },
 118         { SAP_SNA1,           "SNA" },
 119         { SAP_SNA2,           "SNA" },
 120         { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
 121         { SAP_TI,             "Texas Instruments" },
 122         { SAP_BPDU,           "Spanning Tree BPDU" },
 123         { SAP_RS511,          "EIA RS-511 Manufacturing Message Service" },
 124         { SAP_X25,            "ISO 8208 (X.25 over 802.2)" },
 125         /*
 126          * XXX - setting the group bit of SAP_X25 make 0x7F; is this just
 127          * a group version of that?
 128          */
 129         { 0x7F,               "ISO 802.2" },
 130         { SAP_XNS,            "XNS" },
 131         { SAP_NESTAR,         "Nestar" },
 132         { SAP_PROWAY_ASLM,    "PROWAY (IEC955) Active Station List Maintenance" },
 133         { SAP_ARP,            "ARP" },  /* XXX - hand to "dissect_arp()"? */
 134         { SAP_SNAP,           "SNAP" },
 135         { SAP_VINES1,         "Banyan Vines" },
 136         { SAP_VINES2,         "Banyan Vines" },
 137         { SAP_NETWARE,        "NetWare" },
 138         { SAP_NETBIOS,        "NetBIOS" },
 139         { SAP_IBMNM,          "IBM Net Management" },
 140         { SAP_RPL1,           "Remote Program Load" },
 141         { SAP_UB,             "Ungermann-Bass" },
 142         { SAP_RPL2,           "Remote Program Load" },
 143         { SAP_OSINL,          "ISO Network Layer" },
 144         { SAP_GLOBAL,         "Global LSAP" },
 145         { 0x00,               NULL }
 146 };
 147
 148 static struct sap_info  saps[] = {
 149         { SAP_IP,                       capture_ip },
 150         { SAP_NETWARE,                  capture_ipx },
 151         { SAP_NETBIOS,                  capture_netbios },
 152         { 0x00,                         NULL}
 153 };
 154
 155 /*
 156  * See
 157  *
 158  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 159  *
 160  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 161  */
 162 const value_string oui_vals[] = {
 163         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 164 /*
 165 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 166 */
 167         { OUI_CISCO,       "Cisco" },
 168         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 169         { OUI_BRIDGED,     "Frame Relay or ATM bridged frames" },
 170                                 /* RFC 2427, RFC 2684 */
 171         { OUI_ATM_FORUM,   "ATM Forum" },
 172         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 173         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 174         { 0,               NULL }
 175 };
 176
 177 static capture_func_t *
 178 sap_capture_func(u_char sap) {
 179         int i=0;
 180
 181         /* look for the second record where sap == 0, which should
 182          * be the last record
 183          */
 184         while (saps[i].sap > 0 || i == 0) {
 185                 if (saps[i].sap == sap) {
 186                         return saps[i].capture_func;
 187                 }
 188                 i++;
 189         }
 190         return NULL;
 191 }
 192
 193 void
 194 capture_llc(const u_char *pd, int offset, int len, packet_counts *ld) {
 195
 196         int             is_snap;
 197         guint16         control;
 198         int             llc_header_len;
 199         guint32         oui;
 200         guint16         etype;
 201         capture_func_t  *capture;
 202
 203         if (!BYTES_ARE_IN_FRAME(offset, len, 2)) {
 204                 ld->other++;
 205                 return;
 206         }
 207         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 208         llc_header_len = 2;     /* DSAP + SSAP */
 209
 210         /*
 211          * XXX - the page referred to in the comment above about the
 212          * Command/Response bit also implies that LLC Type 2 always
 213          * uses extended operation, so we don't need to determine
 214          * whether it's basic or extended operation; is that the case?
 215          */
 216         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT);
 217         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 218         if (is_snap)
 219                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 220         if (!BYTES_ARE_IN_FRAME(offset, len, llc_header_len)) {
 221                 ld->other++;
 222                 return;
 223         }
 224
 225         if (is_snap) {
 226                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 227                 if (XDLC_IS_INFORMATION(control)) {
 228                         etype = pntohs(&pd[offset+6]);
 229                         switch (oui) {
 230
 231                         case OUI_ENCAP_ETHER:
 232                         case OUI_CISCO_90:
 233                         case OUI_APPLE_ATALK:
 234                                 /* No, I have no idea why Apple used
 235                                    one of their own OUIs, rather than
 236                                    OUI_ENCAP_ETHER, and an Ethernet
 237                                    packet type as protocol ID, for
 238                                    AppleTalk data packets - but used
 239                                    OUI_ENCAP_ETHER and an Ethernet
 240                                    packet type for AARP packets. */
 241                                 capture_ethertype(etype, pd, offset+8, len,
 242                                     ld);
 243                                 break;
 244                         case OUI_CISCO:
 245                                 capture_ethertype(etype, pd, offset + 8, len,
 246                                     ld);
 247                                 break;
 248                         default:
 249                                 ld->other++;
 250                                 break;
 251                         }
 252                 }
 253         }
 254         else {
 255                 if (XDLC_IS_INFORMATION(control)) {
 256                         capture = sap_capture_func(pd[offset]);
 257
 258                         /* non-SNAP */
 259                         offset += llc_header_len;
 260
 261                         if (capture) {
 262                                 capture(pd, offset, len, ld);
 263                         }
 264                         else {
 265                                 ld->other++;
 266                         }
 267                 }
 268         }
 269 }
 270
 271 static void
 272 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 273 {
 274         proto_tree      *llc_tree = NULL;
 275         proto_item      *ti = NULL;
 276         int             is_snap;
 277         guint16         control;
 278         int             llc_header_len;
 279         guint8          dsap, ssap;
 280         tvbuff_t        *next_tvb;
 281
 282         if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 283                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "LLC");
 284         }
 285         if (check_col(pinfo->cinfo, COL_INFO)) {
 286                 col_clear(pinfo->cinfo, COL_INFO);
 287         }
 288
 289         dsap = tvb_get_guint8(tvb, 0);
 290         if (tree) {
 291                 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, -1, FALSE);
 292                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 293                 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
 294                         1, dsap & SAP_MASK);
 295                 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
 296                         1, dsap & DSAP_GI_BIT);
 297         } else
 298                 llc_tree = NULL;
 299
 300         ssap = tvb_get_guint8(tvb, 1);
 301         if (tree) {
 302                 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
 303                         1, ssap & SAP_MASK);
 304                 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
 305                         1, ssap & SSAP_CR_BIT);
 306         } else
 307                 llc_tree = NULL;
 308
 309         is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
 310         llc_header_len = 2;     /* DSAP + SSAP */
 311
 312         /*
 313          * XXX - the page referred to in the comment above about the
 314          * Command/Response bit also implies that LLC Type 2 always
 315          * uses extended operation, so we don't need to determine
 316          * whether it's basic or extended operation; is that the case?
 317          */
 318         control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
 319                                 hf_llc_ctrl, ett_llc_ctrl,
 320                                 ssap & SSAP_CR_BIT, TRUE);
 321         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 322         if (is_snap)
 323                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 324
 325         if (tree)
 326                 proto_item_set_len(ti, llc_header_len);
 327
 328         if (is_snap) {
 329                 dissect_snap(tvb, 3, pinfo, tree, llc_tree, control,
 330                     hf_llc_oui, hf_llc_type, hf_llc_pid, 2);
 331         }
 332         else {
 333                 if (check_col(pinfo->cinfo, COL_INFO)) {
 334                         col_append_fstr(pinfo->cinfo, COL_INFO,
 335                             "; DSAP %s %s, SSAP %s %s",
 336                             val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
 337                             dsap & DSAP_GI_BIT ?
 338                               "Group" : "Individual",
 339                             val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
 340                             ssap & SSAP_CR_BIT ?
 341                               "Response" : "Command"
 342                         );
 343                 }
 344
 345                 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
 346                 if (XDLC_IS_INFORMATION(control)) {
 347                         /* non-SNAP */
 348                         /* do lookup with the subdissector table */
 349                         if (!dissector_try_port(subdissector_table, dsap,
 350                             next_tvb, pinfo, tree)) {
 351                                 call_dissector(data_handle,next_tvb, pinfo, tree);
 352                         }
 353                 } else {
 354                         call_dissector(data_handle,next_tvb, pinfo, tree);
 355                 }
 356         }
 357 }
 358
 359 /*
 360  * Dissect SNAP header; used elsewhere, e.g. in the Frame Relay dissector.
 361  */
 362 void
 363 dissect_snap(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree,
 364     proto_tree *snap_tree, int control, int hf_oui, int hf_type, int hf_pid,
 365     int bridge_pad)
 366 {
 367         guint32         oui;
 368         guint16         etype;
 369         tvbuff_t        *next_tvb;
 370
 371         oui =   tvb_get_ntoh24(tvb, offset);
 372         etype = tvb_get_ntohs(tvb, offset+3);
 373
 374         if (check_col(pinfo->cinfo, COL_INFO)) {
 375                 col_append_fstr(pinfo->cinfo, COL_INFO,
 376                     "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
 377                     oui, val_to_str(oui, oui_vals, "Unknown"), etype);
 378         }
 379         if (tree) {
 380                 proto_tree_add_uint(snap_tree, hf_oui, tvb, offset, 3, oui);
 381         }
 382
 383         switch (oui) {
 384
 385         case OUI_ENCAP_ETHER:
 386         case OUI_CISCO_90:
 387         case OUI_APPLE_ATALK:
 388                 /* No, I have no idea why Apple used
 389                    one of their own OUIs, rather than
 390                    OUI_ENCAP_ETHER, and an Ethernet
 391                    packet type as protocol ID, for
 392                    AppleTalk data packets - but used
 393                    OUI_ENCAP_ETHER and an Ethernet
 394                    packet type for AARP packets. */
 395                 if (XDLC_IS_INFORMATION(control)) {
 396                         ethertype(etype, tvb, offset+5,
 397                             pinfo, tree, snap_tree, hf_type, -1);
 398                 } else {
 399                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 400                         call_dissector(data_handle,next_tvb, pinfo, tree);
 401                 }
 402                 break;
 403
 404         case OUI_BRIDGED:
 405                 /*
 406                  * MAC frames bridged over ATM (RFC 2684) or Frame Relay
 407                  * (RFC 2427).
 408                  *
 409                  * We have to figure out how much padding to put
 410                  * into the frame.  We were handed a "bridge_pad"
 411                  * argument which should be 0 for Frame Relay and
 412                  * 2 for ATM; we add to that the amount of padding
 413                  * common to both bridging types.
 414                  */
 415                 if (tree) {
 416                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 417                             etype);
 418                 }
 419
 420                 switch (etype) {
 421
 422                 case BPID_ETH_WITH_FCS:
 423                 case BPID_ETH_WITHOUT_FCS:
 424                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 425                             -1, -1);
 426                         call_dissector(eth_handle, next_tvb, pinfo, tree);
 427                         break;
 428
 429                 case BPID_802_5_WITH_FCS:
 430                 case BPID_802_5_WITHOUT_FCS:
 431                         /*
 432                          * We treat the last padding byte as the Access
 433                          * Control byte, as that's what the Token
 434                          * Ring dissector expects the first byte to
 435                          * be.
 436                          */
 437                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 438                             -1, -1);
 439                         call_dissector(tr_handle, next_tvb, pinfo, tree);
 440                         break;
 441
 442                 case BPID_FDDI_WITH_FCS:
 443                 case BPID_FDDI_WITHOUT_FCS:
 444                         next_tvb = tvb_new_subset(tvb, offset+5+1+bridge_pad,
 445                             -1, -1);
 446                         call_dissector(fddi_handle, next_tvb, pinfo, tree);
 447                         break;
 448
 449                 case BPID_BPDU:
 450                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 451                         call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 452                         break;
 453
 454                 default:
 455                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 456                         call_dissector(data_handle,next_tvb, pinfo, tree);
 457                         break;
 458                 }
 459                 break;
 460
 461         case OUI_CISCO:
 462                 /* So are all CDP packets LLC packets
 463                    with an OUI of OUI_CISCO and a
 464                    protocol ID of 0x2000, or
 465                    are some of them raw or encapsulated
 466                    Ethernet? */
 467                 if (tree) {
 468                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 469                             etype);
 470                 }
 471                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 472                 if (XDLC_IS_INFORMATION(control)) {
 473                         /* do lookup with the subdissector table */
 474                         /* for future reference, 0x0102 is Cisco DRIP */
 475                         if (!dissector_try_port(cisco_subdissector_table,
 476                             etype, next_tvb, pinfo, tree))
 477                                 call_dissector(data_handle,next_tvb, pinfo, tree);
 478                 } else
 479                         call_dissector(data_handle,next_tvb, pinfo, tree);
 480                 break;
 481
 482         case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 483                 if (tree) {
 484                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 485                             etype);
 486                 }
 487                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 488                 call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 489                 break;
 490
 491         default:
 492                 if (tree) {
 493                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 494                             etype);
 495                 }
 496                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 497                 call_dissector(data_handle,next_tvb, pinfo, tree);
 498                 break;
 499         }
 500 }
 501
 502 void
 503 proto_register_llc(void)
 504 {
 505         static struct true_false_string ig_bit = { "Group", "Individual" };
 506         static struct true_false_string cr_bit = { "Response", "Command" };
 507
 508         static hf_register_info hf[] = {
 509                 { &hf_llc_dsap,
 510                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 511                         VALS(sap_vals), 0x0, "", HFILL }},
 512
 513                 { &hf_llc_dsap_ig,
 514                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 515                         &ig_bit, 0x0, "Individual/Group", HFILL }},
 516
 517                 { &hf_llc_ssap,
 518                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 519                         VALS(sap_vals), 0x0, "", HFILL }},
 520
 521                 { &hf_llc_ssap_cr,
 522                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 523                         &cr_bit, 0x0, "Command/Response", HFILL }},
 524
 525                 { &hf_llc_ctrl,
 526                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 527                         NULL, 0x0, "", HFILL }},
 528
 529                 /* registered here but handled in ethertype.c */
 530                 { &hf_llc_type,
 531                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 532                         VALS(etype_vals), 0x0, "", HFILL }},
 533
 534                 { &hf_llc_oui,
 535                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 536                         VALS(oui_vals), 0x0, "", HFILL }},
 537
 538                 { &hf_llc_pid,
 539                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 540                         NULL, 0x0, "", HFILL }}
 541         };
 542         static gint *ett[] = {
 543                 &ett_llc,
 544                 &ett_llc_ctrl,
 545         };
 546
 547         proto_llc = proto_register_protocol("Logical-Link Control", "LLC", "llc");
 548         proto_register_field_array(proto_llc, hf, array_length(hf));
 549         proto_register_subtree_array(ett, array_length(ett));
 550
 551 /* subdissector code */
 552         subdissector_table = register_dissector_table("llc.dsap",
 553           "LLC SAP", FT_UINT8, BASE_HEX);
 554         cisco_subdissector_table = register_dissector_table("llc.cisco_pid",
 555           "Cisco OUI PID", FT_UINT16, BASE_HEX);
 556
 557         register_dissector("llc", dissect_llc, proto_llc);
 558 }
 559
 560 void
 561 proto_reg_handoff_llc(void)
 562 {
 563         dissector_handle_t llc_handle;
 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         data_handle = find_dissector("data");
 574
 575         llc_handle = find_dissector("llc");
 576         dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, llc_handle);
 577 }