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 1.54 2000/04/13 02:36:35 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 "packet-bpdu.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 typedef void (capture_func_t)(const u_char *, int, packet_counts *);
  64 typedef void (dissect_func_t)(const u_char *, int, frame_data *, proto_tree *);
  65
  66 /* The SAP info is split into two tables, one value_string table and one table of sap_info. This is
  67  * so that the value_string can be used in the header field registration.
  68  */
  69 struct sap_info {
  70         guint8  sap;
  71         capture_func_t *capture_func;
  72         dissect_func_t *dissect_func;
  73 };
  74
  75 /*
  76  * Group/Individual bit, in the DSAP.
  77  */
  78 #define DSAP_GI_BIT     0x01
  79
  80 /*
  81  * Command/Response bit, in the SSAP.
  82  *
  83  * The low-order bit of the SSAP apparently determines whether this
  84  * is a request or a response.  (RFC 1390, "Transmission of IP and
  85  * ARP over FDDI Networks", says
  86  *
  87  *      Command frames are identified by having the low order
  88  *      bit of the SSAP address reset to zero.  Response frames
  89  *      have the low order bit of the SSAP address set to one.
  90  *
  91  * and a page I've seen seems to imply that's part of 802.2.)
  92  */
  93 #define SSAP_CR_BIT     0x01
  94
  95 /*
  96  * Mask to extrace the SAP number from the DSAP or the SSAP.
  97  */
  98 #define SAP_MASK        0xFE
  99
 100 #define SAP_SNAP        0xAA
 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         { 0x00,     "NULL LSAP" },
 111         { 0x02,     "LLC Sub-Layer Management" },
 112         { 0x04,     "SNA Path Control" },
 113         { 0x06,     "TCP/IP" },
 114         { 0x08,     "SNA" },
 115         { 0x0C,     "SNA" },
 116         { 0x0E,     "PROWAY (IEC955) Network Management and Initialization" },
 117         { 0x18,     "Texas Instruments" },
 118         { 0x42,     "Spanning Tree BPDU" },
 119         { 0x4E,     "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         { 0x80,     "XNS" },
 127         { 0x86,     "Nestar" },
 128         { 0x8E,     "PROWAY (IEC955) Active Station List Maintenance" },
 129         { 0x98,     "ARP" },    /* XXX - hand to "dissect_arp()"? */
 130         { SAP_SNAP, "SNAP" },
 131         { 0xBA,     "Banyan Vines" },
 132         { 0xBC,     "Banyan Vines" },
 133         { 0xE0,     "NetWare" },
 134         { 0xF0,     "NetBIOS" },
 135         { 0xF4,     "IBM Net Management" },
 136         { 0xF8,     "Remote Program Load" },
 137         { 0xFA,     "Ungermann-Bass" },
 138         { 0xFC,     "Remote Program Load" },
 139         { 0xFE,     "ISO Network Layer" },
 140         { 0xFF,     "Global LSAP" },
 141         { 0x00,     NULL }
 142 };
 143
 144 static struct sap_info  saps[] = {
 145         { 0x00,         NULL,           NULL },
 146         { 0x02,         NULL,           NULL },
 147         { 0x03,         NULL,           NULL },
 148         { 0x04,         NULL,           dissect_sna },
 149         { 0x05,         NULL,           NULL },
 150         { 0x06,         capture_ip,     dissect_ip },
 151         { 0x08,         NULL,           NULL },
 152         { 0x0C,         NULL,           NULL },
 153         { 0x42,         NULL,           dissect_bpdu },
 154         { 0x7F,         NULL,           NULL },
 155         { 0x80,         NULL,           NULL },
 156         { SAP_SNAP,     NULL,           NULL },
 157         { 0xBA,         NULL,           NULL },
 158         { 0xBC,         NULL,           NULL },
 159         { 0xE0,         capture_ipx,    dissect_ipx },
 160         { 0xF0,         capture_netbios, dissect_netbios },
 161         { 0xF4,         NULL,           NULL },
 162         { 0xF5,         NULL,           NULL },
 163         { 0xF8,         NULL,           NULL },
 164         { 0xFC,         NULL,           NULL },
 165         { 0xFE,         NULL,           dissect_osi },
 166         { 0xFF,         NULL,           NULL },
 167         { 0x00,         NULL,           NULL}
 168 };
 169
 170 /*
 171  * See
 172  *
 173  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 174  *
 175  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 176  */
 177 const value_string oui_vals[] = {
 178         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 179 /*
 180 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 181 */
 182         { OUI_CISCO,       "Cisco" },
 183         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 184         { OUI_BFR,         "Bridged Frame-Relay" }, /* RFC 2427 */
 185         { OUI_ATM_FORUM,   "ATM Forum" },
 186         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 187         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 188         { 0,               NULL }
 189 };
 190
 191 static capture_func_t *
 192 sap_capture_func(u_char sap) {
 193         int i=0;
 194
 195         /* look for the second record where sap == 0, which should
 196          * be the last record
 197          */
 198         while (saps[i].sap > 0 || i == 0) {
 199                 if (saps[i].sap == sap) {
 200                         return saps[i].capture_func;
 201                 }
 202                 i++;
 203         }
 204         return NULL;
 205 }
 206
 207 static dissect_func_t *
 208 sap_dissect_func(u_char sap) {
 209         int i=0;
 210
 211         /* look for the second record where sap == 0, which should
 212          * be the last record
 213          */
 214         while (saps[i].sap > 0 || i == 0) {
 215                 if (saps[i].sap == sap) {
 216                         return saps[i].dissect_func;
 217                 }
 218                 i++;
 219         }
 220         return &dissect_data;
 221 }
 222
 223 void
 224 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
 225
 226         int             is_snap;
 227         guint16         control;
 228         int             llc_header_len;
 229         guint32         oui;
 230         guint16         etype;
 231         capture_func_t  *capture;
 232
 233         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 234                 ld->other++;
 235                 return;
 236         }
 237         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 238         llc_header_len = 2;     /* DSAP + SSAP */
 239
 240         /*
 241          * XXX - the page referred to in the comment above about the
 242          * Command/Response bit also implies that LLC Type 2 always
 243          * uses extended operation, so we don't need to determine
 244          * whether it's basic or extended operation; is that the case?
 245          */
 246         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
 247             TRUE);
 248         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 249         if (is_snap)
 250                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 251         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 252                 ld->other++;
 253                 return;
 254         }
 255
 256         if (is_snap) {
 257                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 258                 if (XDLC_IS_INFORMATION(control)) {
 259                         etype = pntohs(&pd[offset+6]);
 260                         switch (oui) {
 261
 262                         case OUI_ENCAP_ETHER:
 263                         case OUI_APPLE_ATALK:
 264                                 /* No, I have no idea why Apple used
 265                                    one of their own OUIs, rather than
 266                                    OUI_ENCAP_ETHER, and an Ethernet
 267                                    packet type as protocol ID, for
 268                                    AppleTalk data packets - but used
 269                                    OUI_ENCAP_ETHER and an Ethernet
 270                                    packet type for AARP packets. */
 271                                 capture_ethertype(etype, offset+8, pd,
 272                                     ld);
 273                                 break;
 274                         case OUI_CISCO:
 275                                 capture_ethertype(etype,
 276                                                 offset + 8, pd, ld);
 277                                 break;
 278                         default:
 279                                 ld->other++;
 280                                 break;
 281                         }
 282                 }
 283         }
 284         else {
 285                 if (XDLC_IS_INFORMATION(control)) {
 286                         capture = sap_capture_func(pd[offset]);
 287
 288                         /* non-SNAP */
 289                         offset += llc_header_len;
 290
 291                         if (capture) {
 292                                 capture(pd, offset, ld);
 293                         }
 294                         else {
 295                                 ld->other++;
 296                         }
 297                 }
 298         }
 299 }
 300
 301 void
 302 dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
 303
 304         proto_tree      *llc_tree = NULL;
 305         proto_item      *ti = NULL;
 306         int             is_snap;
 307         guint16         control;
 308         int             llc_header_len;
 309         guint32         oui;
 310         guint16         etype;
 311         dissect_func_t  *dissect;
 312
 313         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 314                 dissect_data(pd, offset, fd, tree);
 315                 return;
 316         }
 317         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 318         llc_header_len = 2;     /* DSAP + SSAP */
 319
 320         if (check_col(fd, COL_PROTOCOL)) {
 321                 col_add_str(fd, COL_PROTOCOL, "LLC");
 322         }
 323
 324         if (tree) {
 325                 ti = proto_tree_add_item(tree, proto_llc, offset, 0, NULL);
 326                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 327                 proto_tree_add_item(llc_tree, hf_llc_dsap, offset,
 328                         1, pd[offset] & SAP_MASK);
 329                 proto_tree_add_item(llc_tree, hf_llc_dsap_ig, offset,
 330                         1, pd[offset] & DSAP_GI_BIT);
 331                 proto_tree_add_item(llc_tree, hf_llc_ssap, offset+1,
 332                         1, pd[offset+1] & SAP_MASK);
 333                 proto_tree_add_item(llc_tree, hf_llc_ssap_cr, offset+1,
 334                         1, pd[offset+1] & SSAP_CR_BIT);
 335         } else
 336                 llc_tree = NULL;
 337
 338         /*
 339          * XXX - the page referred to in the comment above about the
 340          * Command/Response bit also implies that LLC Type 2 always
 341          * uses extended operation, so we don't need to determine
 342          * whether it's basic or extended operation; is that the case?
 343          */
 344         control = dissect_xdlc_control(pd, offset+2, fd, llc_tree,
 345                                 hf_llc_ctrl, ett_llc_ctrl,
 346                                 pd[offset+1] & SSAP_CR_BIT, TRUE);
 347         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 348         if (is_snap)
 349                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 350         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 351                 dissect_data(pd, offset, fd, tree);
 352                 return;
 353         }
 354         if (tree)
 355                 proto_item_set_len(ti, llc_header_len);
 356
 357         /*
 358          * XXX - do we want to append the SAP information to the stuff
 359          * "dissect_xdlc_control()" put in the COL_INFO column, rather
 360          * than overwriting it?
 361          */
 362         if (is_snap) {
 363                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 364                 etype = pntohs(&pd[offset+6]);
 365                 if (check_col(fd, COL_INFO)) {
 366                         col_add_fstr(fd, COL_INFO, "SNAP, OUI 0x%06X (%s), PID 0x%04X",
 367                             oui, val_to_str(oui, oui_vals, "Unknown"),
 368                             etype);
 369                 }
 370                 if (tree) {
 371                         proto_tree_add_item(llc_tree, hf_llc_oui, offset+3, 3,
 372                                 oui);
 373                 }
 374                 switch (oui) {
 375
 376                 case OUI_ENCAP_ETHER:
 377                 case OUI_APPLE_ATALK:
 378                         /* No, I have no idea why Apple used
 379                            one of their own OUIs, rather than
 380                            OUI_ENCAP_ETHER, and an Ethernet
 381                            packet type as protocol ID, for
 382                            AppleTalk data packets - but used
 383                            OUI_ENCAP_ETHER and an Ethernet
 384                            packet type for AARP packets. */
 385                         if (XDLC_IS_INFORMATION(control)) {
 386                                 ethertype(etype, offset+8, pd,
 387                                     fd, tree, llc_tree, hf_llc_type);
 388                         } else
 389                                 dissect_data(pd, offset+8, fd, tree);
 390                         break;
 391
 392                 case OUI_CISCO:
 393                         /* So are all CDP packets LLC packets
 394                            with an OUI of OUI_CISCO and a
 395                            protocol ID of 0x2000, or
 396                            are some of them raw or encapsulated
 397                            Ethernet? */
 398                         if (tree) {
 399                                 proto_tree_add_item(llc_tree,
 400                                     hf_llc_pid, offset+6, 2, etype);
 401                         }
 402                         if (XDLC_IS_INFORMATION(control)) {
 403                                 switch (etype) {
 404
 405 #if 0
 406                                 case 0x0102:
 407                                         dissect_drip(pd, offset+8, fd, tree);
 408                                         break;
 409 #endif
 410
 411                                 case 0x2000:
 412                                         dissect_cdp(pd, offset+8, fd, tree);
 413                                         break;
 414
 415                                 case 0x2001:
 416                                         dissect_cgmp(pd, offset+8, fd, tree);
 417                                         break;
 418
 419                                 case 0x2003:
 420                                         dissect_vtp(pd, offset+8, fd, tree);
 421                                         break;
 422
 423                                 default:
 424                                         dissect_data(pd, offset+8, fd, tree);
 425                                         break;
 426                                 }
 427                         } else
 428                                 dissect_data(pd, offset+8, fd, tree);
 429                         break;
 430
 431                 case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 432                         if (tree) {
 433                                 proto_tree_add_item(llc_tree,
 434                                 hf_llc_pid, offset+6, 2, etype);
 435                         }
 436                         dissect_bpdu(pd, offset+8, fd, tree);
 437                         break;
 438
 439                 default:
 440                         if (tree) {
 441                                 proto_tree_add_item(llc_tree,
 442                                     hf_llc_pid, offset+6, 2, etype);
 443                         }
 444                         dissect_data(pd, offset+8, fd, tree);
 445                         break;
 446                 }
 447         }
 448         else {
 449                 if (check_col(fd, COL_INFO)) {
 450                         col_add_fstr(fd, COL_INFO,
 451                             "DSAP %s %s, SSAP %s %s",
 452                             val_to_str(pd[offset] & SAP_MASK, sap_vals, "%02x"),
 453                             pd[offset] & DSAP_GI_BIT ?
 454                               "Group" : "Individual",
 455                             val_to_str(pd[offset+1] & SAP_MASK, sap_vals, "%02x"),
 456                             pd[offset+1] & SSAP_CR_BIT ?
 457                               "Response" : "Command"
 458                         );
 459                 }
 460
 461                 if (XDLC_IS_INFORMATION(control)) {
 462                         dissect = sap_dissect_func(pd[offset]);
 463
 464                         /* non-SNAP */
 465                         offset += llc_header_len;
 466
 467                         if (dissect) {
 468                                 dissect(pd, offset, fd, tree);
 469                         }
 470                         else {
 471                                 dissect_data(pd, offset, fd, tree);
 472                         }
 473                 } else {
 474                         offset += llc_header_len;
 475                         dissect_data(pd, offset, fd, tree);
 476                 }
 477         }
 478 }
 479
 480 void
 481 proto_register_llc(void)
 482 {
 483         static struct true_false_string ig_bit = { "Group", "Individual" };
 484         static struct true_false_string cr_bit = { "Response", "Command" };
 485
 486         static hf_register_info hf[] = {
 487                 { &hf_llc_dsap,
 488                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 489                         VALS(sap_vals), 0x0, "" }},
 490
 491                 { &hf_llc_dsap_ig,
 492                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 493                         &ig_bit, 0x0, "Individual/Group" }},
 494
 495                 { &hf_llc_ssap,
 496                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 497                         VALS(sap_vals), 0x0, "" }},
 498
 499                 { &hf_llc_ssap_cr,
 500                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 501                         &cr_bit, 0x0, "Command/Response" }},
 502
 503                 { &hf_llc_ctrl,
 504                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 505                         NULL, 0x0, "" }},
 506
 507                 /* registered here but handled in ethertype.c */
 508                 { &hf_llc_type,
 509                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 510                         VALS(etype_vals), 0x0, "" }},
 511
 512                 { &hf_llc_oui,
 513                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 514                         VALS(oui_vals), 0x0, ""}},
 515
 516                 { &hf_llc_pid,
 517                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 518                         NULL, 0x0, ""}}
 519         };
 520         static gint *ett[] = {
 521                 &ett_llc,
 522                 &ett_llc_ctrl,
 523         };
 524
 525         proto_llc = proto_register_protocol ("Logical-Link Control", "llc" );
 526         proto_register_field_array(proto_llc, hf, array_length(hf));
 527         proto_register_subtree_array(ett, array_length(ett));
 528 }