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 1.74 2001/01/03 06:55:29 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-ip.h"
  42 #include "packet-ipx.h"
  43 #include "packet-netbios.h"
  44 #include "packet-osi.h"
  45 #include "packet-sna.h"
  46
  47 static int proto_llc = -1;
  48 static int hf_llc_dsap = -1;
  49 static int hf_llc_ssap = -1;
  50 static int hf_llc_dsap_ig = -1;
  51 static int hf_llc_ssap_cr = -1;
  52 static int hf_llc_ctrl = -1;
  53 static int hf_llc_type = -1;
  54 static int hf_llc_oui = -1;
  55 static int hf_llc_pid = -1;
  56
  57 static gint ett_llc = -1;
  58 static gint ett_llc_ctrl = -1;
  59
  60 static dissector_table_t subdissector_table;
  61 static dissector_table_t cisco_subdissector_table;
  62
  63 static dissector_handle_t bpdu_handle;
  64
  65 typedef void (capture_func_t)(const u_char *, int, packet_counts *);
  66
  67 /* The SAP info is split into two tables, one value_string table and one
  68  * table of sap_info. This is so that the value_string can be used in the
  69  * header field registration.
  70  */
  71 struct sap_info {
  72         guint8  sap;
  73         capture_func_t *capture_func;
  74 };
  75
  76 /*
  77  * Group/Individual bit, in the DSAP.
  78  */
  79 #define DSAP_GI_BIT     0x01
  80
  81 /*
  82  * Command/Response bit, in the SSAP.
  83  *
  84  * The low-order bit of the SSAP apparently determines whether this
  85  * is a request or a response.  (RFC 1390, "Transmission of IP and
  86  * ARP over FDDI Networks", says
  87  *
  88  *      Command frames are identified by having the low order
  89  *      bit of the SSAP address reset to zero.  Response frames
  90  *      have the low order bit of the SSAP address set to one.
  91  *
  92  * and a page I've seen seems to imply that's part of 802.2.)
  93  */
  94 #define SSAP_CR_BIT     0x01
  95
  96 /*
  97  * Mask to extrace the SAP number from the DSAP or the SSAP.
  98  */
  99 #define SAP_MASK        0xFE
 100
 101 /*
 102  * These are for SSAP and DSAP, wth last bit always zero.
 103  * XXX - some DSAPs come in separate "individual" and "group" versions,
 104  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
 105  * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
 106  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
 107  */
 108 static const value_string sap_vals[] = {
 109         { SAP_NULL,           "NULL LSAP" },
 110         { SAP_LLC_SLMGMT,     "LLC Sub-Layer Management" },
 111         { SAP_SNA_PATHCTRL,   "SNA Path Control" },
 112         { SAP_IP,             "TCP/IP" },
 113         { SAP_SNA1,           "SNA" },
 114         { SAP_SNA2,           "SNA" },
 115         { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
 116         { SAP_TI,             "Texas Instruments" },
 117         { SAP_BPDU,           "Spanning Tree BPDU" },
 118         { SAP_RS511,          "EIA RS-511 Manufacturing Message Service" },
 119 #if 0
 120         /* XXX - setting the group bit makes this 0x7F; is that just
 121            a group version of this? */
 122         { 0x7E,               "ISO 8208 (X.25 over 802.2 Type 2)" },
 123 #endif
 124         { 0x7F,               "ISO 802.2" },
 125         { SAP_XNS,            "XNS" },
 126         { SAP_NESTAR,         "Nestar" },
 127         { SAP_PROWAY_ASLM,    "PROWAY (IEC955) Active Station List Maintenance" },
 128         { SAP_ARP,            "ARP" },  /* XXX - hand to "dissect_arp()"? */
 129         { SAP_SNAP,           "SNAP" },
 130         { SAP_VINES1,         "Banyan Vines" },
 131         { SAP_VINES2,         "Banyan Vines" },
 132         { SAP_NETWARE,        "NetWare" },
 133         { SAP_NETBIOS,        "NetBIOS" },
 134         { SAP_IBMNM,          "IBM Net Management" },
 135         { SAP_RPL1,           "Remote Program Load" },
 136         { SAP_UB,             "Ungermann-Bass" },
 137         { SAP_RPL2,           "Remote Program Load" },
 138         { SAP_OSINL,          "ISO Network Layer" },
 139         { SAP_GLOBAL,         "Global LSAP" },
 140         { 0x00,               NULL }
 141 };
 142
 143 static struct sap_info  saps[] = {
 144         { SAP_IP,                       capture_ip },
 145         { SAP_NETWARE,                  capture_ipx },
 146         { SAP_NETBIOS,                  capture_netbios },
 147         { 0x00,                         NULL}
 148 };
 149
 150 /*
 151  * See
 152  *
 153  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 154  *
 155  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 156  */
 157 const value_string oui_vals[] = {
 158         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 159 /*
 160 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 161 */
 162         { OUI_CISCO,       "Cisco" },
 163         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 164         { OUI_BFR,         "Bridged Frame-Relay" }, /* RFC 2427 */
 165         { OUI_ATM_FORUM,   "ATM Forum" },
 166         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 167         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 168         { 0,               NULL }
 169 };
 170
 171 static capture_func_t *
 172 sap_capture_func(u_char sap) {
 173         int i=0;
 174
 175         /* look for the second record where sap == 0, which should
 176          * be the last record
 177          */
 178         while (saps[i].sap > 0 || i == 0) {
 179                 if (saps[i].sap == sap) {
 180                         return saps[i].capture_func;
 181                 }
 182                 i++;
 183         }
 184         return NULL;
 185 }
 186
 187 void
 188 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
 189
 190         int             is_snap;
 191         guint16         control;
 192         int             llc_header_len;
 193         guint32         oui;
 194         guint16         etype;
 195         capture_func_t  *capture;
 196
 197         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 198                 ld->other++;
 199                 return;
 200         }
 201         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 202         llc_header_len = 2;     /* DSAP + SSAP */
 203
 204         /*
 205          * XXX - the page referred to in the comment above about the
 206          * Command/Response bit also implies that LLC Type 2 always
 207          * uses extended operation, so we don't need to determine
 208          * whether it's basic or extended operation; is that the case?
 209          */
 210         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
 211             TRUE);
 212         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 213         if (is_snap)
 214                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 215         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 216                 ld->other++;
 217                 return;
 218         }
 219
 220         if (is_snap) {
 221                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 222                 if (XDLC_IS_INFORMATION(control)) {
 223                         etype = pntohs(&pd[offset+6]);
 224                         switch (oui) {
 225
 226                         case OUI_ENCAP_ETHER:
 227                         case OUI_APPLE_ATALK:
 228                                 /* No, I have no idea why Apple used
 229                                    one of their own OUIs, rather than
 230                                    OUI_ENCAP_ETHER, and an Ethernet
 231                                    packet type as protocol ID, for
 232                                    AppleTalk data packets - but used
 233                                    OUI_ENCAP_ETHER and an Ethernet
 234                                    packet type for AARP packets. */
 235                                 capture_ethertype(etype, offset+8, pd,
 236                                     ld);
 237                                 break;
 238                         case OUI_CISCO:
 239                                 capture_ethertype(etype,
 240                                                 offset + 8, pd, ld);
 241                                 break;
 242                         default:
 243                                 ld->other++;
 244                                 break;
 245                         }
 246                 }
 247         }
 248         else {
 249                 if (XDLC_IS_INFORMATION(control)) {
 250                         capture = sap_capture_func(pd[offset]);
 251
 252                         /* non-SNAP */
 253                         offset += llc_header_len;
 254
 255                         if (capture) {
 256                                 capture(pd, offset, ld);
 257                         }
 258                         else {
 259                                 ld->other++;
 260                         }
 261                 }
 262         }
 263 }
 264
 265 void
 266 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 267 {
 268         proto_tree      *llc_tree = NULL;
 269         proto_item      *ti = NULL;
 270         int             is_snap;
 271         guint16         control;
 272         int             llc_header_len;
 273         guint32         oui;
 274         guint16         etype;
 275         guint8          dsap, ssap;
 276         tvbuff_t        *next_tvb;
 277         const guint8    *pd;
 278         int             offset;
 279
 280         CHECK_DISPLAY_AS_DATA(proto_llc, tvb, pinfo, tree);
 281
 282         pinfo->current_proto = "LLC";
 283
 284         if (check_col(pinfo->fd, COL_PROTOCOL)) {
 285                 col_set_str(pinfo->fd, COL_PROTOCOL, "LLC");
 286         }
 287
 288         dsap = tvb_get_guint8(tvb, 0);
 289         if (tree) {
 290                 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, 0, FALSE);
 291                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 292                 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
 293                         1, dsap & SAP_MASK);
 294                 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
 295                         1, dsap & DSAP_GI_BIT);
 296         } else
 297                 llc_tree = NULL;
 298
 299         ssap = tvb_get_guint8(tvb, 1);
 300         if (tree) {
 301                 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
 302                         1, ssap & SAP_MASK);
 303                 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
 304                         1, ssap & SSAP_CR_BIT);
 305         } else
 306                 llc_tree = NULL;
 307
 308         is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
 309         llc_header_len = 2;     /* DSAP + SSAP */
 310
 311         /*
 312          * XXX - the page referred to in the comment above about the
 313          * Command/Response bit also implies that LLC Type 2 always
 314          * uses extended operation, so we don't need to determine
 315          * whether it's basic or extended operation; is that the case?
 316          */
 317         control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
 318                                 hf_llc_ctrl, ett_llc_ctrl,
 319                                 ssap & SSAP_CR_BIT, TRUE);
 320         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 321         if (is_snap)
 322                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 323
 324         if (tree)
 325                 proto_item_set_len(ti, llc_header_len);
 326
 327         if (is_snap) {
 328                 oui =   tvb_get_ntoh24(tvb, 3);
 329                 etype = tvb_get_ntohs(tvb, 6);
 330
 331                 if (check_col(pinfo->fd, COL_INFO)) {
 332                         col_append_fstr(pinfo->fd, COL_INFO, "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
 333                             oui, val_to_str(oui, oui_vals, "Unknown"),
 334                             etype);
 335                 }
 336                 if (tree) {
 337                         proto_tree_add_uint(llc_tree, hf_llc_oui, tvb, 3, 3,
 338                                 oui);
 339                 }
 340
 341                 next_tvb = tvb_new_subset(tvb, 8, -1, -1);
 342                 tvb_compat(next_tvb, &pd, &offset);
 343
 344                 switch (oui) {
 345
 346                 case OUI_ENCAP_ETHER:
 347                 case OUI_APPLE_ATALK:
 348                         /* No, I have no idea why Apple used
 349                            one of their own OUIs, rather than
 350                            OUI_ENCAP_ETHER, and an Ethernet
 351                            packet type as protocol ID, for
 352                            AppleTalk data packets - but used
 353                            OUI_ENCAP_ETHER and an Ethernet
 354                            packet type for AARP packets. */
 355                         if (XDLC_IS_INFORMATION(control)) {
 356                                 ethertype(etype, tvb, 8,
 357                                     pinfo, tree, llc_tree, hf_llc_type);
 358                         } else
 359                                 dissect_data(next_tvb, 0, pinfo, tree);
 360                         break;
 361
 362                 case OUI_CISCO:
 363                         /* So are all CDP packets LLC packets
 364                            with an OUI of OUI_CISCO and a
 365                            protocol ID of 0x2000, or
 366                            are some of them raw or encapsulated
 367                            Ethernet? */
 368                         if (tree) {
 369                                 proto_tree_add_uint(llc_tree,
 370                                     hf_llc_pid, tvb, 6, 2, etype);
 371                         }
 372                         if (XDLC_IS_INFORMATION(control)) {
 373                                 /* do lookup with the subdissector table */
 374                                 /* for future reference, 0x0102 is Cisco DRIP */
 375                                 if (!dissector_try_port(cisco_subdissector_table,
 376                                     etype, next_tvb, pinfo, tree))
 377                                         dissect_data(next_tvb, 0, pinfo, tree);
 378                         } else
 379                                 dissect_data(next_tvb, 0, pinfo, tree);
 380                         break;
 381
 382                 case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 383                         if (tree) {
 384                                 proto_tree_add_uint(llc_tree,
 385                                     hf_llc_pid, tvb, 6, 2, etype);
 386                         }
 387                         call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 388                         break;
 389
 390                 default:
 391                         if (tree) {
 392                                 proto_tree_add_uint(llc_tree,
 393                                     hf_llc_pid, tvb, 6, 2, etype);
 394                         }
 395                         dissect_data(next_tvb, 0, pinfo, tree);
 396                         break;
 397                 }
 398         }
 399         else {
 400                 if (check_col(pinfo->fd, COL_INFO)) {
 401                         col_append_fstr(pinfo->fd, COL_INFO,
 402                             "; DSAP %s %s, SSAP %s %s",
 403                             val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
 404                             dsap & DSAP_GI_BIT ?
 405                               "Group" : "Individual",
 406                             val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
 407                             ssap & SSAP_CR_BIT ?
 408                               "Response" : "Command"
 409                         );
 410                 }
 411
 412                 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
 413                 if (XDLC_IS_INFORMATION(control)) {
 414                         /* non-SNAP */
 415                         /* do lookup with the subdissector table */
 416                         if (!dissector_try_port(subdissector_table, dsap,
 417                             next_tvb, pinfo, tree)) {
 418                                 dissect_data(next_tvb, 0, pinfo, tree);
 419                         }
 420                 } else {
 421                         dissect_data(next_tvb, 0, pinfo, tree);
 422                 }
 423         }
 424 }
 425
 426 void
 427 proto_register_llc(void)
 428 {
 429         static struct true_false_string ig_bit = { "Group", "Individual" };
 430         static struct true_false_string cr_bit = { "Response", "Command" };
 431
 432         static hf_register_info hf[] = {
 433                 { &hf_llc_dsap,
 434                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 435                         VALS(sap_vals), 0x0, "" }},
 436
 437                 { &hf_llc_dsap_ig,
 438                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 439                         &ig_bit, 0x0, "Individual/Group" }},
 440
 441                 { &hf_llc_ssap,
 442                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 443                         VALS(sap_vals), 0x0, "" }},
 444
 445                 { &hf_llc_ssap_cr,
 446                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 447                         &cr_bit, 0x0, "Command/Response" }},
 448
 449                 { &hf_llc_ctrl,
 450                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 451                         NULL, 0x0, "" }},
 452
 453                 /* registered here but handled in ethertype.c */
 454                 { &hf_llc_type,
 455                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 456                         VALS(etype_vals), 0x0, "" }},
 457
 458                 { &hf_llc_oui,
 459                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 460                         VALS(oui_vals), 0x0, ""}},
 461
 462                 { &hf_llc_pid,
 463                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 464                         NULL, 0x0, ""}}
 465         };
 466         static gint *ett[] = {
 467                 &ett_llc,
 468                 &ett_llc_ctrl,
 469         };
 470
 471         proto_llc = proto_register_protocol("Logical-Link Control", "LLC", "llc");
 472         proto_register_field_array(proto_llc, hf, array_length(hf));
 473         proto_register_subtree_array(ett, array_length(ett));
 474
 475 /* subdissector code */
 476         subdissector_table = register_dissector_table("llc.dsap");
 477         cisco_subdissector_table = register_dissector_table("llc.cisco_pid");
 478 }
 479
 480 void
 481 proto_reg_handoff_llc(void)
 482 {
 483         /*
 484          * Get a handle for the BPDU dissector.
 485          */
 486         bpdu_handle = find_dissector("bpdu");
 487
 488         dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, dissect_llc);
 489 }