packet-llc.c

   1 /* packet-llc.c
   2  * Routines for IEEE 802.2 LLC layer
   3  * Gilbert Ramirez <gramirez@tivoli.com>
   4  *
   5  * $Id: packet-llc.c,v 1.51 2000/04/09 18:33:26 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         { 0,               NULL }
 188 };
 189
 190 static capture_func_t *
 191 sap_capture_func(u_char sap) {
 192         int i=0;
 193
 194         /* look for the second record where sap == 0, which should
 195          * be the last record
 196          */
 197         while (saps[i].sap > 0 || i == 0) {
 198                 if (saps[i].sap == sap) {
 199                         return saps[i].capture_func;
 200                 }
 201                 i++;
 202         }
 203         return NULL;
 204 }
 205
 206 static dissect_func_t *
 207 sap_dissect_func(u_char sap) {
 208         int i=0;
 209
 210         /* look for the second record where sap == 0, which should
 211          * be the last record
 212          */
 213         while (saps[i].sap > 0 || i == 0) {
 214                 if (saps[i].sap == sap) {
 215                         return saps[i].dissect_func;
 216                 }
 217                 i++;
 218         }
 219         return &dissect_data;
 220 }
 221
 222 void
 223 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
 224
 225         int             is_snap;
 226         guint16         control;
 227         int             llc_header_len;
 228         guint32         oui;
 229         guint16         etype;
 230         capture_func_t  *capture;
 231
 232         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 233                 ld->other++;
 234                 return;
 235         }
 236         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 237         llc_header_len = 2;     /* DSAP + SSAP */
 238
 239         /*
 240          * XXX - the page referred to in the comment above about the
 241          * Command/Response bit also implies that LLC Type 2 always
 242          * uses extended operation, so we don't need to determine
 243          * whether it's basic or extended operation; is that the case?
 244          */
 245         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
 246             TRUE);
 247         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 248         if (is_snap)
 249                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 250         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 251                 ld->other++;
 252                 return;
 253         }
 254
 255         if (is_snap) {
 256                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 257                 if (XDLC_IS_INFORMATION(control)) {
 258                         etype = pntohs(&pd[offset+6]);
 259                         switch (oui) {
 260
 261                         case OUI_ENCAP_ETHER:
 262                         case OUI_APPLE_ATALK:
 263                                 /* No, I have no idea why Apple used
 264                                    one of their own OUIs, rather than
 265                                    OUI_ENCAP_ETHER, and an Ethernet
 266                                    packet type as protocol ID, for
 267                                    AppleTalk data packets - but used
 268                                    OUI_ENCAP_ETHER and an Ethernet
 269                                    packet type for AARP packets. */
 270                                 capture_ethertype(etype, offset+8, pd,
 271                                     ld);
 272                                 break;
 273                         case OUI_CISCO:
 274                                 capture_ethertype(etype,
 275                                                 offset + 8, pd, ld);
 276                                 break;
 277                         default:
 278                                 ld->other++;
 279                                 break;
 280                         }
 281                 }
 282         }
 283         else {
 284                 if (XDLC_IS_INFORMATION(control)) {
 285                         capture = sap_capture_func(pd[offset]);
 286
 287                         /* non-SNAP */
 288                         offset += llc_header_len;
 289
 290                         if (capture) {
 291                                 capture(pd, offset, ld);
 292                         }
 293                         else {
 294                                 ld->other++;
 295                         }
 296                 }
 297         }
 298 }
 299
 300 void
 301 dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
 302
 303         proto_tree      *llc_tree = NULL;
 304         proto_item      *ti = NULL;
 305         int             is_snap;
 306         guint16         control;
 307         int             llc_header_len;
 308         guint32         oui;
 309         guint16         etype;
 310         dissect_func_t  *dissect;
 311
 312         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 313                 dissect_data(pd, offset, fd, tree);
 314                 return;
 315         }
 316         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 317         llc_header_len = 2;     /* DSAP + SSAP */
 318
 319         if (check_col(fd, COL_PROTOCOL)) {
 320                 col_add_str(fd, COL_PROTOCOL, "LLC");
 321         }
 322
 323         if (tree) {
 324                 ti = proto_tree_add_item(tree, proto_llc, offset, 0, NULL);
 325                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 326                 proto_tree_add_item(llc_tree, hf_llc_dsap, offset,
 327                         1, pd[offset] & SAP_MASK);
 328                 proto_tree_add_item(llc_tree, hf_llc_dsap_ig, offset,
 329                         1, pd[offset] & DSAP_GI_BIT);
 330                 proto_tree_add_item(llc_tree, hf_llc_ssap, offset+1,
 331                         1, pd[offset+1] & SAP_MASK);
 332                 proto_tree_add_item(llc_tree, hf_llc_ssap_cr, offset+1,
 333                         1, pd[offset+1] & SSAP_CR_BIT);
 334         } else
 335                 llc_tree = NULL;
 336
 337         /*
 338          * XXX - the page referred to in the comment above about the
 339          * Command/Response bit also implies that LLC Type 2 always
 340          * uses extended operation, so we don't need to determine
 341          * whether it's basic or extended operation; is that the case?
 342          */
 343         control = dissect_xdlc_control(pd, offset+2, fd, llc_tree,
 344                                 hf_llc_ctrl, ett_llc_ctrl,
 345                                 pd[offset+1] & SSAP_CR_BIT, TRUE);
 346         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 347         if (is_snap)
 348                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 349         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 350                 dissect_data(pd, offset, fd, tree);
 351                 return;
 352         }
 353         if (tree)
 354                 proto_item_set_len(ti, llc_header_len);
 355
 356         /*
 357          * XXX - do we want to append the SAP information to the stuff
 358          * "dissect_xdlc_control()" put in the COL_INFO column, rather
 359          * than overwriting it?
 360          */
 361         if (is_snap) {
 362                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 363                 etype = pntohs(&pd[offset+6]);
 364                 if (check_col(fd, COL_INFO)) {
 365                         col_add_fstr(fd, COL_INFO, "SNAP, OUI 0x%06X (%s), PID 0x%04X",
 366                             oui, val_to_str(oui, oui_vals, "Unknown"),
 367                             etype);
 368                 }
 369                 if (tree) {
 370                         proto_tree_add_item(llc_tree, hf_llc_oui, offset+3, 3,
 371                                 oui);
 372                 }
 373                 switch (oui) {
 374
 375                 case OUI_ENCAP_ETHER:
 376                 case OUI_APPLE_ATALK:
 377                         /* No, I have no idea why Apple used
 378                            one of their own OUIs, rather than
 379                            OUI_ENCAP_ETHER, and an Ethernet
 380                            packet type as protocol ID, for
 381                            AppleTalk data packets - but used
 382                            OUI_ENCAP_ETHER and an Ethernet
 383                            packet type for AARP packets. */
 384                         if (XDLC_IS_INFORMATION(control)) {
 385                                 ethertype(etype, offset+8, pd,
 386                                     fd, tree, llc_tree, hf_llc_type);
 387                         } else
 388                                 dissect_data(pd, offset+8, fd, tree);
 389                         break;
 390
 391                 case OUI_CISCO:
 392                         /* So are all CDP packets LLC packets
 393                            with an OUI of OUI_CISCO and a
 394                            protocol ID of 0x2000, or
 395                            are some of them raw or encapsulated
 396                            Ethernet? */
 397                         if (tree) {
 398                                 proto_tree_add_item(llc_tree,
 399                                     hf_llc_pid, offset+6, 2, etype);
 400                         }
 401                         if (XDLC_IS_INFORMATION(control)) {
 402                                 switch (etype) {
 403
 404 #if 0
 405                                 case 0x0102:
 406                                         dissect_drip(pd, offset+8, fd, tree);
 407                                         break;
 408 #endif
 409
 410                                 case 0x2000:
 411                                         dissect_cdp(pd, offset+8, fd, tree);
 412                                         break;
 413
 414                                 case 0x2001:
 415                                         dissect_cgmp(pd, offset+8, fd, tree);
 416                                         break;
 417
 418                                 case 0x2003:
 419                                         dissect_vtp(pd, offset+8, fd, tree);
 420                                         break;
 421
 422                                 default:
 423                                         dissect_data(pd, offset+8, fd, tree);
 424                                         break;
 425                                 }
 426                         } else
 427                                 dissect_data(pd, offset+8, fd, tree);
 428                         break;
 429
 430                 default:
 431                         if (tree) {
 432                                 proto_tree_add_item(llc_tree,
 433                                     hf_llc_pid, offset+6, 2, etype);
 434                         }
 435                         dissect_data(pd, offset+8, fd, tree);
 436                         break;
 437                 }
 438         }
 439         else {
 440                 if (check_col(fd, COL_INFO)) {
 441                         col_add_fstr(fd, COL_INFO,
 442                             "DSAP %s %s, SSAP %s %s",
 443                             val_to_str(pd[offset] & SAP_MASK, sap_vals, "%02x"),
 444                             pd[offset] & DSAP_GI_BIT ?
 445                               "Group" : "Individual",
 446                             val_to_str(pd[offset+1] & SAP_MASK, sap_vals, "%02x"),
 447                             pd[offset+1] & SSAP_CR_BIT ?
 448                               "Response" : "Command"
 449                         );
 450                 }
 451
 452                 if (XDLC_IS_INFORMATION(control)) {
 453                         dissect = sap_dissect_func(pd[offset]);
 454
 455                         /* non-SNAP */
 456                         offset += llc_header_len;
 457
 458                         if (dissect) {
 459                                 dissect(pd, offset, fd, tree);
 460                         }
 461                         else {
 462                                 dissect_data(pd, offset, fd, tree);
 463                         }
 464                 } else {
 465                         offset += llc_header_len;
 466                         dissect_data(pd, offset, fd, tree);
 467                 }
 468         }
 469 }
 470
 471 void
 472 proto_register_llc(void)
 473 {
 474         static struct true_false_string ig_bit = { "Group", "Individual" };
 475         static struct true_false_string cr_bit = { "Response", "Command" };
 476
 477         static hf_register_info hf[] = {
 478                 { &hf_llc_dsap,
 479                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 480                         VALS(sap_vals), 0x0, "" }},
 481
 482                 { &hf_llc_dsap_ig,
 483                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 484                         &ig_bit, 0x0, "Individual/Group" }},
 485
 486                 { &hf_llc_ssap,
 487                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 488                         VALS(sap_vals), 0x0, "" }},
 489
 490                 { &hf_llc_ssap_cr,
 491                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 492                         &cr_bit, 0x0, "Command/Response" }},
 493
 494                 { &hf_llc_ctrl,
 495                 { "Control", "llc.control", FT_UINT8, BASE_HEX,
 496                         NULL, 0x0, "" }},
 497
 498                 /* registered here but handled in ethertype.c */
 499                 { &hf_llc_type,
 500                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 501                         VALS(etype_vals), 0x0, "" }},
 502
 503                 { &hf_llc_oui,
 504                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 505                         VALS(oui_vals), 0x0, ""}},
 506
 507                 { &hf_llc_pid,
 508                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 509                         NULL, 0x0, ""}}
 510         };
 511         static gint *ett[] = {
 512                 &ett_llc,
 513                 &ett_llc_ctrl,
 514         };
 515
 516         proto_llc = proto_register_protocol ("Logical-Link Control", "llc" );
 517         proto_register_field_array(proto_llc, hf, array_length(hf));
 518         proto_register_subtree_array(ett, array_length(ett));
 519 }