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 1.69 2000/08/25 06:31:25 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@zing.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  25  */
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #ifdef HAVE_SYS_TYPES_H
  32 # include <sys/types.h>
  33 #endif
  34
  35 #include <glib.h>
  36 #include "packet.h"
  37 #include "oui.h"
  38 #include "xdlc.h"
  39 #include "etypes.h"
  40 #include "llcsaps.h"
  41 #include "packet-bpdu.h"
  42 #include "packet-cdp.h"
  43 #include "packet-cgmp.h"
  44 #include "packet-ip.h"
  45 #include "packet-ipx.h"
  46 #include "packet-netbios.h"
  47 #include "packet-osi.h"
  48 #include "packet-sna.h"
  49 #include "packet-vtp.h"
  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
  66 typedef void (capture_func_t)(const u_char *, int, packet_counts *);
  67
  68 /* The SAP info is split into two tables, one value_string table and one
  69  * table of sap_info. This is so that the value_string can be used in the
  70  * header field registration.
  71  */
  72 struct sap_info {
  73         guint8  sap;
  74         capture_func_t *capture_func;
  75 };
  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 #if 0
 121         /* XXX - setting the group bit makes this 0x7F; is that just
 122            a group version of this? */
 123         { 0x7E,               "ISO 8208 (X.25 over 802.2 Type 2)" },
 124 #endif
 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 static struct sap_info  saps[] = {
 145         { SAP_IP,                       capture_ip },
 146         { SAP_NETWARE,                  capture_ipx },
 147         { SAP_NETBIOS,                  capture_netbios },
 148         { 0x00,                         NULL}
 149 };
 150
 151 /*
 152  * See
 153  *
 154  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 155  *
 156  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 157  */
 158 const value_string oui_vals[] = {
 159         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 160 /*
 161 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 162 */
 163         { OUI_CISCO,       "Cisco" },
 164         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 165         { OUI_BFR,         "Bridged Frame-Relay" }, /* RFC 2427 */
 166         { OUI_ATM_FORUM,   "ATM Forum" },
 167         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 168         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 169         { 0,               NULL }
 170 };
 171
 172 static capture_func_t *
 173 sap_capture_func(u_char sap) {
 174         int i=0;
 175
 176         /* look for the second record where sap == 0, which should
 177          * be the last record
 178          */
 179         while (saps[i].sap > 0 || i == 0) {
 180                 if (saps[i].sap == sap) {
 181                         return saps[i].capture_func;
 182                 }
 183                 i++;
 184         }
 185         return NULL;
 186 }
 187
 188 void
 189 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
 190
 191         int             is_snap;
 192         guint16         control;
 193         int             llc_header_len;
 194         guint32         oui;
 195         guint16         etype;
 196         capture_func_t  *capture;
 197
 198         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 199                 ld->other++;
 200                 return;
 201         }
 202         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 203         llc_header_len = 2;     /* DSAP + SSAP */
 204
 205         /*
 206          * XXX - the page referred to in the comment above about the
 207          * Command/Response bit also implies that LLC Type 2 always
 208          * uses extended operation, so we don't need to determine
 209          * whether it's basic or extended operation; is that the case?
 210          */
 211         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
 212             TRUE);
 213         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 214         if (is_snap)
 215                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 216         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 217                 ld->other++;
 218                 return;
 219         }
 220
 221         if (is_snap) {
 222                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 223                 if (XDLC_IS_INFORMATION(control)) {
 224                         etype = pntohs(&pd[offset+6]);
 225                         switch (oui) {
 226
 227                         case OUI_ENCAP_ETHER:
 228                         case OUI_APPLE_ATALK:
 229                                 /* No, I have no idea why Apple used
 230                                    one of their own OUIs, rather than
 231                                    OUI_ENCAP_ETHER, and an Ethernet
 232                                    packet type as protocol ID, for
 233                                    AppleTalk data packets - but used
 234                                    OUI_ENCAP_ETHER and an Ethernet
 235                                    packet type for AARP packets. */
 236                                 capture_ethertype(etype, offset+8, pd,
 237                                     ld);
 238                                 break;
 239                         case OUI_CISCO:
 240                                 capture_ethertype(etype,
 241                                                 offset + 8, pd, ld);
 242                                 break;
 243                         default:
 244                                 ld->other++;
 245                                 break;
 246                         }
 247                 }
 248         }
 249         else {
 250                 if (XDLC_IS_INFORMATION(control)) {
 251                         capture = sap_capture_func(pd[offset]);
 252
 253                         /* non-SNAP */
 254                         offset += llc_header_len;
 255
 256                         if (capture) {
 257                                 capture(pd, offset, ld);
 258                         }
 259                         else {
 260                                 ld->other++;
 261                         }
 262                 }
 263         }
 264 }
 265
 266 void
 267 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 268 {
 269         proto_tree      *llc_tree = NULL;
 270         proto_item      *ti = NULL;
 271         int             is_snap;
 272         guint16         control;
 273         int             llc_header_len;
 274         guint32         oui;
 275         guint16         etype;
 276         guint8          dsap, ssap;
 277         tvbuff_t        *next_tvb;
 278         const guint8    *pd;
 279         int             offset;
 280
 281         CHECK_DISPLAY_AS_DATA(proto_llc, tvb, pinfo, tree);
 282
 283         pinfo->current_proto = "LLC";
 284
 285         if (check_col(pinfo->fd, COL_PROTOCOL)) {
 286                 col_add_str(pinfo->fd, COL_PROTOCOL, "LLC");
 287         }
 288
 289         dsap = tvb_get_guint8(tvb, 0);
 290         if (tree) {
 291                 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, 0, 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                 oui =   tvb_get_ntoh24(tvb, 3);
 330                 etype = tvb_get_ntohs(tvb, 6);
 331
 332                 if (check_col(pinfo->fd, COL_INFO)) {
 333                         col_append_fstr(pinfo->fd, COL_INFO, "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
 334                             oui, val_to_str(oui, oui_vals, "Unknown"),
 335                             etype);
 336                 }
 337                 if (tree) {
 338                         proto_tree_add_uint(llc_tree, hf_llc_oui, tvb, 3, 3,
 339                                 oui);
 340                 }
 341
 342                 next_tvb = tvb_new_subset(tvb, 8, -1, -1);
 343                 tvb_compat(next_tvb, &pd, &offset);
 344
 345                 switch (oui) {
 346
 347                 case OUI_ENCAP_ETHER:
 348                 case OUI_APPLE_ATALK:
 349                         /* No, I have no idea why Apple used
 350                            one of their own OUIs, rather than
 351                            OUI_ENCAP_ETHER, and an Ethernet
 352                            packet type as protocol ID, for
 353                            AppleTalk data packets - but used
 354                            OUI_ENCAP_ETHER and an Ethernet
 355                            packet type for AARP packets. */
 356                         if (XDLC_IS_INFORMATION(control)) {
 357                                 ethertype(etype, tvb, 8,
 358                                     pinfo, tree, llc_tree, hf_llc_type);
 359                         } else
 360                                 dissect_data(next_tvb, pinfo, tree);
 361                         break;
 362
 363                 case OUI_CISCO:
 364                         /* So are all CDP packets LLC packets
 365                            with an OUI of OUI_CISCO and a
 366                            protocol ID of 0x2000, or
 367                            are some of them raw or encapsulated
 368                            Ethernet? */
 369                         if (tree) {
 370                                 proto_tree_add_uint(llc_tree,
 371                                     hf_llc_pid, tvb, 6, 2, etype);
 372                         }
 373                         if (XDLC_IS_INFORMATION(control)) {
 374                                 switch (etype) {
 375
 376 #if 0
 377                                 case 0x0102:
 378                                         dissect_drip(pd, offset, pinfo->fd, tree);
 379                                         break;
 380 #endif
 381
 382                                 case 0x2000:
 383                                         dissect_cdp(pd, offset, pinfo->fd, tree);
 384                                         break;
 385
 386                                 case 0x2001:
 387                                         dissect_cgmp(pd, offset, pinfo->fd, tree);
 388                                         break;
 389
 390                                 case 0x2003:
 391                                         dissect_vtp(pd, offset, pinfo->fd, tree);
 392                                         break;
 393
 394                                 default:
 395                                         dissect_data(next_tvb, pinfo, tree);
 396                                         break;
 397                                 }
 398                         } else
 399                                 dissect_data(next_tvb, pinfo, tree);
 400                         break;
 401
 402                 case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 403                         if (tree) {
 404                                 proto_tree_add_uint(llc_tree,
 405                                 hf_llc_pid, tvb, 6, 2, etype);
 406                         }
 407                         dissect_bpdu(pd, offset, pinfo->fd, tree);
 408                         break;
 409
 410                 default:
 411                         if (tree) {
 412                                 proto_tree_add_uint(llc_tree,
 413                                     hf_llc_pid, tvb, 6, 2, etype);
 414                         }
 415                         dissect_data(next_tvb, pinfo, tree);
 416                         break;
 417                 }
 418         }
 419         else {
 420                 if (check_col(pinfo->fd, COL_INFO)) {
 421                         col_append_fstr(pinfo->fd, COL_INFO,
 422                             "; DSAP %s %s, SSAP %s %s",
 423                             val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
 424                             dsap & DSAP_GI_BIT ?
 425                               "Group" : "Individual",
 426                             val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
 427                             ssap & SSAP_CR_BIT ?
 428                               "Response" : "Command"
 429                         );
 430                 }
 431
 432                 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
 433                 if (XDLC_IS_INFORMATION(control)) {
 434                         /* non-SNAP */
 435                         /* do lookup with the subdissector table */
 436                         if (!dissector_try_port(subdissector_table, dsap,
 437                             next_tvb, pinfo, tree)) {
 438                                 dissect_data(next_tvb, pinfo, tree);
 439                         }
 440                 } else {
 441                         dissect_data(next_tvb, pinfo, tree);
 442                 }
 443         }
 444 }
 445
 446 void
 447 proto_register_llc(void)
 448 {
 449         static struct true_false_string ig_bit = { "Group", "Individual" };
 450         static struct true_false_string cr_bit = { "Response", "Command" };
 451
 452         static hf_register_info hf[] = {
 453                 { &hf_llc_dsap,
 454                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 455                         VALS(sap_vals), 0x0, "" }},
 456
 457                 { &hf_llc_dsap_ig,
 458                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 459                         &ig_bit, 0x0, "Individual/Group" }},
 460
 461                 { &hf_llc_ssap,
 462                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 463                         VALS(sap_vals), 0x0, "" }},
 464
 465                 { &hf_llc_ssap_cr,
 466                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 467                         &cr_bit, 0x0, "Command/Response" }},
 468
 469                 { &hf_llc_ctrl,
 470                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 471                         NULL, 0x0, "" }},
 472
 473                 /* registered here but handled in ethertype.c */
 474                 { &hf_llc_type,
 475                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 476                         VALS(etype_vals), 0x0, "" }},
 477
 478                 { &hf_llc_oui,
 479                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 480                         VALS(oui_vals), 0x0, ""}},
 481
 482                 { &hf_llc_pid,
 483                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 484                         NULL, 0x0, ""}}
 485         };
 486         static gint *ett[] = {
 487                 &ett_llc,
 488                 &ett_llc_ctrl,
 489         };
 490
 491         proto_llc = proto_register_protocol ("Logical-Link Control", "llc" );
 492         proto_register_field_array(proto_llc, hf, array_length(hf));
 493         proto_register_subtree_array(ett, array_length(ett));
 494
 495 /* subdissector code */
 496         subdissector_table = register_dissector_table("llc.dsap");
 497 }