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 1.72 2000/11/29 05:16:15 gram 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 "packet-cdp.h"
  42 #include "packet-cgmp.h"
  43 #include "packet-ip.h"
  44 #include "packet-ipx.h"
  45 #include "packet-netbios.h"
  46 #include "packet-osi.h"
  47 #include "packet-sna.h"
  48 #include "packet-vtp.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
  65 static dissector_handle_t bpdu_handle;
  66
  67 typedef void (capture_func_t)(const u_char *, int, packet_counts *);
  68
  69 /* The SAP info is split into two tables, one value_string table and one
  70  * table of sap_info. This is so that the value_string can be used in the
  71  * header field registration.
  72  */
  73 struct sap_info {
  74         guint8  sap;
  75         capture_func_t *capture_func;
  76 };
  77
  78 /*
  79  * Group/Individual bit, in the DSAP.
  80  */
  81 #define DSAP_GI_BIT     0x01
  82
  83 /*
  84  * Command/Response bit, in the SSAP.
  85  *
  86  * The low-order bit of the SSAP apparently determines whether this
  87  * is a request or a response.  (RFC 1390, "Transmission of IP and
  88  * ARP over FDDI Networks", says
  89  *
  90  *      Command frames are identified by having the low order
  91  *      bit of the SSAP address reset to zero.  Response frames
  92  *      have the low order bit of the SSAP address set to one.
  93  *
  94  * and a page I've seen seems to imply that's part of 802.2.)
  95  */
  96 #define SSAP_CR_BIT     0x01
  97
  98 /*
  99  * Mask to extrace the SAP number from the DSAP or the SSAP.
 100  */
 101 #define SAP_MASK        0xFE
 102
 103 /*
 104  * These are for SSAP and DSAP, wth last bit always zero.
 105  * XXX - some DSAPs come in separate "individual" and "group" versions,
 106  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
 107  * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
 108  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
 109  */
 110 static const value_string sap_vals[] = {
 111         { SAP_NULL,           "NULL LSAP" },
 112         { SAP_LLC_SLMGMT,     "LLC Sub-Layer Management" },
 113         { SAP_SNA_PATHCTRL,   "SNA Path Control" },
 114         { SAP_IP,             "TCP/IP" },
 115         { SAP_SNA1,           "SNA" },
 116         { SAP_SNA2,           "SNA" },
 117         { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
 118         { SAP_TI,             "Texas Instruments" },
 119         { SAP_BPDU,           "Spanning Tree BPDU" },
 120         { SAP_RS511,          "EIA RS-511 Manufacturing Message Service" },
 121 #if 0
 122         /* XXX - setting the group bit makes this 0x7F; is that just
 123            a group version of this? */
 124         { 0x7E,               "ISO 8208 (X.25 over 802.2 Type 2)" },
 125 #endif
 126         { 0x7F,               "ISO 802.2" },
 127         { SAP_XNS,            "XNS" },
 128         { SAP_NESTAR,         "Nestar" },
 129         { SAP_PROWAY_ASLM,    "PROWAY (IEC955) Active Station List Maintenance" },
 130         { SAP_ARP,            "ARP" },  /* XXX - hand to "dissect_arp()"? */
 131         { SAP_SNAP,           "SNAP" },
 132         { SAP_VINES1,         "Banyan Vines" },
 133         { SAP_VINES2,         "Banyan Vines" },
 134         { SAP_NETWARE,        "NetWare" },
 135         { SAP_NETBIOS,        "NetBIOS" },
 136         { SAP_IBMNM,          "IBM Net Management" },
 137         { SAP_RPL1,           "Remote Program Load" },
 138         { SAP_UB,             "Ungermann-Bass" },
 139         { SAP_RPL2,           "Remote Program Load" },
 140         { SAP_OSINL,          "ISO Network Layer" },
 141         { SAP_GLOBAL,         "Global LSAP" },
 142         { 0x00,               NULL }
 143 };
 144
 145 static struct sap_info  saps[] = {
 146         { SAP_IP,                       capture_ip },
 147         { SAP_NETWARE,                  capture_ipx },
 148         { SAP_NETBIOS,                  capture_netbios },
 149         { 0x00,                         NULL}
 150 };
 151
 152 /*
 153  * See
 154  *
 155  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 156  *
 157  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 158  */
 159 const value_string oui_vals[] = {
 160         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 161 /*
 162 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 163 */
 164         { OUI_CISCO,       "Cisco" },
 165         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 166         { OUI_BFR,         "Bridged Frame-Relay" }, /* RFC 2427 */
 167         { OUI_ATM_FORUM,   "ATM Forum" },
 168         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 169         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 170         { 0,               NULL }
 171 };
 172
 173 static capture_func_t *
 174 sap_capture_func(u_char sap) {
 175         int i=0;
 176
 177         /* look for the second record where sap == 0, which should
 178          * be the last record
 179          */
 180         while (saps[i].sap > 0 || i == 0) {
 181                 if (saps[i].sap == sap) {
 182                         return saps[i].capture_func;
 183                 }
 184                 i++;
 185         }
 186         return NULL;
 187 }
 188
 189 void
 190 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
 191
 192         int             is_snap;
 193         guint16         control;
 194         int             llc_header_len;
 195         guint32         oui;
 196         guint16         etype;
 197         capture_func_t  *capture;
 198
 199         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 200                 ld->other++;
 201                 return;
 202         }
 203         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 204         llc_header_len = 2;     /* DSAP + SSAP */
 205
 206         /*
 207          * XXX - the page referred to in the comment above about the
 208          * Command/Response bit also implies that LLC Type 2 always
 209          * uses extended operation, so we don't need to determine
 210          * whether it's basic or extended operation; is that the case?
 211          */
 212         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
 213             TRUE);
 214         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 215         if (is_snap)
 216                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 217         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 218                 ld->other++;
 219                 return;
 220         }
 221
 222         if (is_snap) {
 223                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 224                 if (XDLC_IS_INFORMATION(control)) {
 225                         etype = pntohs(&pd[offset+6]);
 226                         switch (oui) {
 227
 228                         case OUI_ENCAP_ETHER:
 229                         case OUI_APPLE_ATALK:
 230                                 /* No, I have no idea why Apple used
 231                                    one of their own OUIs, rather than
 232                                    OUI_ENCAP_ETHER, and an Ethernet
 233                                    packet type as protocol ID, for
 234                                    AppleTalk data packets - but used
 235                                    OUI_ENCAP_ETHER and an Ethernet
 236                                    packet type for AARP packets. */
 237                                 capture_ethertype(etype, offset+8, pd,
 238                                     ld);
 239                                 break;
 240                         case OUI_CISCO:
 241                                 capture_ethertype(etype,
 242                                                 offset + 8, pd, ld);
 243                                 break;
 244                         default:
 245                                 ld->other++;
 246                                 break;
 247                         }
 248                 }
 249         }
 250         else {
 251                 if (XDLC_IS_INFORMATION(control)) {
 252                         capture = sap_capture_func(pd[offset]);
 253
 254                         /* non-SNAP */
 255                         offset += llc_header_len;
 256
 257                         if (capture) {
 258                                 capture(pd, offset, ld);
 259                         }
 260                         else {
 261                                 ld->other++;
 262                         }
 263                 }
 264         }
 265 }
 266
 267 void
 268 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 269 {
 270         proto_tree      *llc_tree = NULL;
 271         proto_item      *ti = NULL;
 272         int             is_snap;
 273         guint16         control;
 274         int             llc_header_len;
 275         guint32         oui;
 276         guint16         etype;
 277         guint8          dsap, ssap;
 278         tvbuff_t        *next_tvb;
 279         const guint8    *pd;
 280         int             offset;
 281
 282         CHECK_DISPLAY_AS_DATA(proto_llc, tvb, pinfo, tree);
 283
 284         pinfo->current_proto = "LLC";
 285
 286         if (check_col(pinfo->fd, COL_PROTOCOL)) {
 287                 col_set_str(pinfo->fd, COL_PROTOCOL, "LLC");
 288         }
 289
 290         dsap = tvb_get_guint8(tvb, 0);
 291         if (tree) {
 292                 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, 0, FALSE);
 293                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 294                 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
 295                         1, dsap & SAP_MASK);
 296                 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
 297                         1, dsap & DSAP_GI_BIT);
 298         } else
 299                 llc_tree = NULL;
 300
 301         ssap = tvb_get_guint8(tvb, 1);
 302         if (tree) {
 303                 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
 304                         1, ssap & SAP_MASK);
 305                 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
 306                         1, ssap & SSAP_CR_BIT);
 307         } else
 308                 llc_tree = NULL;
 309
 310         is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
 311         llc_header_len = 2;     /* DSAP + SSAP */
 312
 313         /*
 314          * XXX - the page referred to in the comment above about the
 315          * Command/Response bit also implies that LLC Type 2 always
 316          * uses extended operation, so we don't need to determine
 317          * whether it's basic or extended operation; is that the case?
 318          */
 319         control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
 320                                 hf_llc_ctrl, ett_llc_ctrl,
 321                                 ssap & SSAP_CR_BIT, TRUE);
 322         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 323         if (is_snap)
 324                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 325
 326         if (tree)
 327                 proto_item_set_len(ti, llc_header_len);
 328
 329         if (is_snap) {
 330                 oui =   tvb_get_ntoh24(tvb, 3);
 331                 etype = tvb_get_ntohs(tvb, 6);
 332
 333                 if (check_col(pinfo->fd, COL_INFO)) {
 334                         col_append_fstr(pinfo->fd, COL_INFO, "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
 335                             oui, val_to_str(oui, oui_vals, "Unknown"),
 336                             etype);
 337                 }
 338                 if (tree) {
 339                         proto_tree_add_uint(llc_tree, hf_llc_oui, tvb, 3, 3,
 340                                 oui);
 341                 }
 342
 343                 next_tvb = tvb_new_subset(tvb, 8, -1, -1);
 344                 tvb_compat(next_tvb, &pd, &offset);
 345
 346                 switch (oui) {
 347
 348                 case OUI_ENCAP_ETHER:
 349                 case OUI_APPLE_ATALK:
 350                         /* No, I have no idea why Apple used
 351                            one of their own OUIs, rather than
 352                            OUI_ENCAP_ETHER, and an Ethernet
 353                            packet type as protocol ID, for
 354                            AppleTalk data packets - but used
 355                            OUI_ENCAP_ETHER and an Ethernet
 356                            packet type for AARP packets. */
 357                         if (XDLC_IS_INFORMATION(control)) {
 358                                 ethertype(etype, tvb, 8,
 359                                     pinfo, tree, llc_tree, hf_llc_type);
 360                         } else
 361                                 dissect_data(next_tvb, 0, pinfo, tree);
 362                         break;
 363
 364                 case OUI_CISCO:
 365                         /* So are all CDP packets LLC packets
 366                            with an OUI of OUI_CISCO and a
 367                            protocol ID of 0x2000, or
 368                            are some of them raw or encapsulated
 369                            Ethernet? */
 370                         if (tree) {
 371                                 proto_tree_add_uint(llc_tree,
 372                                     hf_llc_pid, tvb, 6, 2, etype);
 373                         }
 374                         if (XDLC_IS_INFORMATION(control)) {
 375                                 switch (etype) {
 376
 377 #if 0
 378                                 case 0x0102:
 379                                         dissect_drip(pd, offset, pinfo->fd, tree);
 380                                         break;
 381 #endif
 382
 383                                 case 0x2000:
 384                                         dissect_cdp(pd, offset, pinfo->fd, tree);
 385                                         break;
 386
 387                                 case 0x2001:
 388                                         dissect_cgmp(pd, offset, pinfo->fd, tree);
 389                                         break;
 390
 391                                 case 0x2003:
 392                                         dissect_vtp(pd, offset, pinfo->fd, tree);
 393                                         break;
 394
 395                                 default:
 396                                         dissect_data(next_tvb, 0, pinfo, tree);
 397                                         break;
 398                                 }
 399                         } else
 400                                 dissect_data(next_tvb, 0, pinfo, tree);
 401                         break;
 402
 403                 case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 404                         if (tree) {
 405                                 proto_tree_add_uint(llc_tree,
 406                                 hf_llc_pid, tvb, 6, 2, etype);
 407                         }
 408                         call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 409                         break;
 410
 411                 default:
 412                         if (tree) {
 413                                 proto_tree_add_uint(llc_tree,
 414                                     hf_llc_pid, tvb, 6, 2, etype);
 415                         }
 416                         dissect_data(next_tvb, 0, pinfo, tree);
 417                         break;
 418                 }
 419         }
 420         else {
 421                 if (check_col(pinfo->fd, COL_INFO)) {
 422                         col_append_fstr(pinfo->fd, COL_INFO,
 423                             "; DSAP %s %s, SSAP %s %s",
 424                             val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
 425                             dsap & DSAP_GI_BIT ?
 426                               "Group" : "Individual",
 427                             val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
 428                             ssap & SSAP_CR_BIT ?
 429                               "Response" : "Command"
 430                         );
 431                 }
 432
 433                 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
 434                 if (XDLC_IS_INFORMATION(control)) {
 435                         /* non-SNAP */
 436                         /* do lookup with the subdissector table */
 437                         if (!dissector_try_port(subdissector_table, dsap,
 438                             next_tvb, pinfo, tree)) {
 439                                 dissect_data(next_tvb, 0, pinfo, tree);
 440                         }
 441                 } else {
 442                         dissect_data(next_tvb, 0, pinfo, tree);
 443                 }
 444         }
 445 }
 446
 447 void
 448 proto_register_llc(void)
 449 {
 450         static struct true_false_string ig_bit = { "Group", "Individual" };
 451         static struct true_false_string cr_bit = { "Response", "Command" };
 452
 453         static hf_register_info hf[] = {
 454                 { &hf_llc_dsap,
 455                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 456                         VALS(sap_vals), 0x0, "" }},
 457
 458                 { &hf_llc_dsap_ig,
 459                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 460                         &ig_bit, 0x0, "Individual/Group" }},
 461
 462                 { &hf_llc_ssap,
 463                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 464                         VALS(sap_vals), 0x0, "" }},
 465
 466                 { &hf_llc_ssap_cr,
 467                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 468                         &cr_bit, 0x0, "Command/Response" }},
 469
 470                 { &hf_llc_ctrl,
 471                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 472                         NULL, 0x0, "" }},
 473
 474                 /* registered here but handled in ethertype.c */
 475                 { &hf_llc_type,
 476                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 477                         VALS(etype_vals), 0x0, "" }},
 478
 479                 { &hf_llc_oui,
 480                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 481                         VALS(oui_vals), 0x0, ""}},
 482
 483                 { &hf_llc_pid,
 484                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 485                         NULL, 0x0, ""}}
 486         };
 487         static gint *ett[] = {
 488                 &ett_llc,
 489                 &ett_llc_ctrl,
 490         };
 491
 492         proto_llc = proto_register_protocol ("Logical-Link Control", "llc" );
 493         proto_register_field_array(proto_llc, hf, array_length(hf));
 494         proto_register_subtree_array(ett, array_length(ett));
 495
 496 /* subdissector code */
 497         subdissector_table = register_dissector_table("llc.dsap");
 498 }
 499
 500 void
 501 proto_reg_handoff_llc(void)
 502 {
 503         /*
 504          * Get a handle for the BPDU dissector.
 505          */
 506         bpdu_handle = find_dissector("bpdu");
 507         dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, dissect_llc);
 508 }