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 1.42 2000/01/24 01:45:12 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
  41 static int proto_llc = -1;
  42 static int hf_llc_dsap = -1;
  43 static int hf_llc_ssap = -1;
  44 static int hf_llc_dsap_ig = -1;
  45 static int hf_llc_ssap_cr = -1;
  46 static int hf_llc_ctrl = -1;
  47 static int hf_llc_type = -1;
  48 static int hf_llc_oui = -1;
  49 static int hf_llc_pid = -1;
  50
  51 static gint ett_llc = -1;
  52 static gint ett_llc_ctrl = -1;
  53
  54 typedef void (capture_func_t)(const u_char *, int, packet_counts *);
  55 typedef void (dissect_func_t)(const u_char *, int, frame_data *, proto_tree *);
  56
  57 /* The SAP info is split into two tables, one value_string table and one table of sap_info. This is
  58  * so that the value_string can be used in the header field registration.
  59  */
  60 struct sap_info {
  61         guint8  sap;
  62         capture_func_t *capture_func;
  63         dissect_func_t *dissect_func;
  64 };
  65
  66 /*
  67  * Group/Individual bit, in the DSAP.
  68  */
  69 #define DSAP_GI_BIT     0x01
  70
  71 /*
  72  * Command/Response bit, in the SSAP.
  73  *
  74  * The low-order bit of the SSAP apparently determines whether this
  75  * is a request or a response.  (RFC 1390, "Transmission of IP and
  76  * ARP over FDDI Networks", says
  77  *
  78  *      Command frames are identified by having the low order
  79  *      bit of the SSAP address reset to zero.  Response frames
  80  *      have the low order bit of the SSAP address set to one.
  81  *
  82  * and a page I've seen seems to imply that's part of 802.2.)
  83  */
  84 #define SSAP_CR_BIT     0x01
  85
  86 /*
  87  * Mask to extrace the SAP number from the DSAP or the SSAP.
  88  */
  89 #define SAP_MASK        0xFE
  90
  91 /*
  92  * These are for SSAP and DSAP, wth last bit always zero.
  93  * XXX - some DSAPs come in separate "individual" and "group" versions,
  94  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
  95  * IBM SNA Path Control, IBM Net Management), and, whilst 0xFE is
  96  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
  97  */
  98 static const value_string sap_vals[] = {
  99         { 0x00, "NULL LSAP" },
 100         { 0x02, "LLC Sub-Layer Management" },
 101         { 0x04, "SNA Path Control" },
 102         { 0x06, "TCP/IP" },
 103         { 0x08, "SNA" },
 104         { 0x0C, "SNA" },
 105         { 0x42, "Spanning Tree BPDU" },
 106         { 0x7F, "ISO 802.2" },
 107         { 0x80, "XNS" },
 108         { 0xAA, "SNAP" },
 109         { 0xBA, "Banyan Vines" },
 110         { 0xBC, "Banyan Vines" },
 111         { 0xE0, "NetWare" },
 112         { 0xF0, "NetBIOS" },
 113         { 0xF4, "IBM Net Management" },
 114         { 0xF8, "Remote Program Load" },
 115         { 0xFC, "Remote Program Load" },
 116         { 0xFE, "ISO Network Layer" },
 117         { 0xFF, "Global LSAP" },
 118         { 0x00, NULL }
 119 };
 120
 121 static struct sap_info  saps[] = {
 122         { 0x00, NULL,           NULL },
 123         { 0x02, NULL,           NULL },
 124         { 0x03, NULL,           NULL },
 125         { 0x04, NULL,           dissect_sna },
 126         { 0x05, NULL,           NULL },
 127         { 0x06, capture_ip,     dissect_ip },
 128         { 0x08, NULL,           NULL },
 129         { 0x0C, NULL,           NULL },
 130         { 0x42, NULL,           dissect_bpdu },
 131         { 0x7F, NULL,           NULL },
 132         { 0x80, NULL,           NULL },
 133         { 0xAA, NULL,           NULL },
 134         { 0xBA, NULL,           NULL },
 135         { 0xBC, NULL,           NULL },
 136         { 0xE0, capture_ipx,    dissect_ipx },
 137         { 0xF0, capture_netbios, dissect_netbios },
 138         { 0xF4, NULL,           NULL },
 139         { 0xF5, NULL,           NULL },
 140         { 0xF8, NULL,           NULL },
 141         { 0xFC, NULL,           NULL },
 142         { 0xFE, NULL,           dissect_osi },
 143         { 0xFF, NULL,           NULL },
 144         { 0x00, NULL,           NULL}
 145 };
 146
 147 static const value_string llc_ctrl_vals[] = {
 148         { 0, "Information Transfer" },
 149         { 1, "Supervisory" },
 150         { 2, "Unknown" },
 151         { 3, "Unnumbered Information" },
 152         { 0, NULL }
 153 };
 154
 155 const value_string oui_vals[] = {
 156         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 157 /*
 158 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 159 */
 160         { OUI_CISCO,       "Cisco" },
 161         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 162         { OUI_BFR,         "Bridged Frame-Relay" }, /* RFC 2427 */
 163         { OUI_ATM_FORUM,   "ATM Forum" },
 164         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 165         { 0,               NULL }
 166 };
 167
 168 static capture_func_t *
 169 sap_capture_func(u_char sap) {
 170         int i=0;
 171
 172         /* look for the second record where sap == 0, which should
 173          * be the last record
 174          */
 175         while (saps[i].sap > 0 || i == 0) {
 176                 if (saps[i].sap == sap) {
 177                         return saps[i].capture_func;
 178                 }
 179                 i++;
 180         }
 181         return NULL;
 182 }
 183
 184 static dissect_func_t *
 185 sap_dissect_func(u_char sap) {
 186         int i=0;
 187
 188         /* look for the second record where sap == 0, which should
 189          * be the last record
 190          */
 191         while (saps[i].sap > 0 || i == 0) {
 192                 if (saps[i].sap == sap) {
 193                         return saps[i].dissect_func;
 194                 }
 195                 i++;
 196         }
 197         return dissect_data;
 198 }
 199
 200 void
 201 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
 202
 203         int             is_snap;
 204         guint16         control;
 205         int             llc_header_len;
 206         guint32         oui;
 207         guint16         etype;
 208         capture_func_t  *capture;
 209
 210         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 211                 ld->other++;
 212                 return;
 213         }
 214         is_snap = (pd[offset] == 0xAA) && (pd[offset+1] == 0xAA);
 215         llc_header_len = 2;     /* DSAP + SSAP */
 216
 217         /*
 218          * XXX - the page referred to in the comment above about the
 219          * Command/Response bit also implies that LLC Type 2 always
 220          * uses extended operation, so we don't need to determine
 221          * whether it's basic or extended operation; is that the case?
 222          */
 223         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
 224             TRUE);
 225         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 226         if (is_snap)
 227                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 228         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 229                 ld->other++;
 230                 return;
 231         }
 232
 233         if (is_snap) {
 234                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 235                 if (XDLC_HAS_PAYLOAD(control)) {
 236                         /*
 237                          * This frame has a payload to be analyzed.
 238                          */
 239                         etype = pntohs(&pd[offset+6]);
 240                         switch (oui) {
 241
 242                         case OUI_ENCAP_ETHER:
 243                         case OUI_APPLE_ATALK:
 244                                 /* No, I have no idea why Apple used
 245                                    one of their own OUIs, rather than
 246                                    OUI_ENCAP_ETHER, and an Ethernet
 247                                    packet type as protocol ID, for
 248                                    AppleTalk data packets - but used
 249                                    OUI_ENCAP_ETHER and an Ethernet
 250                                    packet type for AARP packets. */
 251                                 capture_ethertype(etype, offset+8, pd,
 252                                     ld);
 253                                 break;
 254                         case OUI_CISCO:
 255                                 capture_ethertype(etype,
 256                                                 offset + 8, pd, ld);
 257                                 break;
 258                         default:
 259                                 ld->other++;
 260                                 break;
 261                         }
 262                 }
 263         }
 264         else {
 265                 if (XDLC_HAS_PAYLOAD(control)) {
 266                         /*
 267                          * This frame has a payload to be analyzed.
 268                          */
 269                         capture = sap_capture_func(pd[offset]);
 270
 271                         /* non-SNAP */
 272                         offset += llc_header_len;
 273
 274                         if (capture) {
 275                                 capture(pd, offset, ld);
 276                         }
 277                         else {
 278                                 ld->other++;
 279                         }
 280                 }
 281         }
 282 }
 283
 284 void
 285 dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
 286
 287         proto_tree      *llc_tree = NULL;
 288         proto_item      *ti = NULL;
 289         int             is_snap;
 290         guint16         control;
 291         int             llc_header_len;
 292         guint32         oui;
 293         guint16         etype;
 294         dissect_func_t  *dissect;
 295
 296         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 297                 dissect_data(pd, offset, fd, tree);
 298                 return;
 299         }
 300         is_snap = (pd[offset] == 0xAA) && (pd[offset+1] == 0xAA);
 301         llc_header_len = 2;     /* DSAP + SSAP */
 302
 303         if (check_col(fd, COL_PROTOCOL)) {
 304                 col_add_str(fd, COL_PROTOCOL, "LLC");
 305         }
 306
 307         if (tree) {
 308                 ti = proto_tree_add_item(tree, proto_llc, offset, 0, NULL);
 309                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 310                 proto_tree_add_item(llc_tree, hf_llc_dsap, offset,
 311                         1, pd[offset] & SAP_MASK);
 312                 proto_tree_add_item(llc_tree, hf_llc_dsap_ig, offset,
 313                         1, pd[offset] & DSAP_GI_BIT);
 314                 proto_tree_add_item(llc_tree, hf_llc_ssap, offset+1,
 315                         1, pd[offset+1] & SAP_MASK);
 316                 proto_tree_add_item(llc_tree, hf_llc_ssap_cr, offset+1,
 317                         1, pd[offset+1] & SSAP_CR_BIT);
 318         } else
 319                 llc_tree = NULL;
 320
 321         /*
 322          * XXX - the page referred to in the comment above about the
 323          * Command/Response bit also implies that LLC Type 2 always
 324          * uses extended operation, so we don't need to determine
 325          * whether it's basic or extended operation; is that the case?
 326          */
 327         control = dissect_xdlc_control(pd, offset+2, fd, llc_tree,
 328                                 hf_llc_ctrl, ett_llc_ctrl,
 329                                 pd[offset+1] & SSAP_CR_BIT, TRUE);
 330         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 331         if (is_snap)
 332                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 333         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 334                 dissect_data(pd, offset, fd, tree);
 335                 return;
 336         }
 337         if (tree)
 338                 proto_item_set_len(ti, llc_header_len);
 339
 340         /*
 341          * XXX - do we want to append the SAP information to the stuff
 342          * "dissect_xdlc_control()" put in the COL_INFO column, rather
 343          * than overwriting it?
 344          */
 345         if (is_snap) {
 346                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 347                 etype = pntohs(&pd[offset+6]);
 348                 if (check_col(fd, COL_INFO)) {
 349                         col_add_fstr(fd, COL_INFO, "SNAP, OUI 0x%06X (%s), PID 0x%04X",
 350                             oui, val_to_str(oui, oui_vals, "Unknown"),
 351                             etype);
 352                 }
 353                 if (tree) {
 354                         proto_tree_add_item(llc_tree, hf_llc_oui, offset+3, 3,
 355                                 oui);
 356                 }
 357                 switch (oui) {
 358
 359                 case OUI_ENCAP_ETHER:
 360                 case OUI_APPLE_ATALK:
 361                         /* No, I have no idea why Apple used
 362                            one of their own OUIs, rather than
 363                            OUI_ENCAP_ETHER, and an Ethernet
 364                            packet type as protocol ID, for
 365                            AppleTalk data packets - but used
 366                            OUI_ENCAP_ETHER and an Ethernet
 367                            packet type for AARP packets. */
 368                         if (XDLC_HAS_PAYLOAD(control)) {
 369                                 /*
 370                                  * This frame has a payload to be analyzed.
 371                                  * XXX - I've seen a U frame (for a SNAP
 372                                  * protocol with OUI 00-80-5F, belonging
 373                                  * to Compaq, and a PID of 0002) with a
 374                                  * function of TEST and, apparently, with
 375                                  * a payload - the data in the frame
 376                                  * following the LLC header included the
 377                                  * Unicode string "NTFS", so, unless that's
 378                                  * crud left over from an earlier frame whose
 379                                  * buffer was reused for this frame, and the
 380                                  * length was mysteriously set to include the
 381                                  * leftover crud, TEST frames can have data,
 382                                  * just as UI frames can.
 383                                  */
 384                                 ethertype(etype, offset+8, pd,
 385                                     fd, tree, llc_tree, hf_llc_type);
 386                         }
 387                         break;
 388
 389                 case OUI_CISCO:
 390                         /* So are all CDP packets LLC packets
 391                            with an OUI of OUI_CISCO and a
 392                            protocol ID of 0x2000, or
 393                            are some of them raw or encapsulated
 394                            Ethernet? */
 395                         if (tree) {
 396                                 proto_tree_add_item(llc_tree,
 397                                     hf_llc_pid, offset+6, 2, etype);
 398                         }
 399                         if (XDLC_HAS_PAYLOAD(control)) {
 400                                 /*
 401                                  * This frame has a payload to be analyzed.
 402                                  */
 403                                 switch (etype) {
 404
 405                                 case 0x2000:
 406                                         dissect_cdp(pd, offset+8, fd, tree);
 407                                         break;
 408
 409                                 default:
 410                                         dissect_data(pd, offset+8, fd, tree);
 411                                         break;
 412                                 }
 413                         }
 414                         break;
 415
 416                 default:
 417                         if (tree) {
 418                                 proto_tree_add_item(llc_tree,
 419                                     hf_llc_pid, offset+6, 2, etype);
 420                         }
 421                         if (XDLC_HAS_PAYLOAD(control)) {
 422                                 /*
 423                                  * This frame has a payload to be analyzed.
 424                                  */
 425                                 dissect_data(pd, offset+8, fd, tree);
 426                         }
 427                         break;
 428                 }
 429         }
 430         else {
 431                 if (check_col(fd, COL_INFO)) {
 432                         col_add_fstr(fd, COL_INFO,
 433                             "DSAP %s %s, SSAP %s %s",
 434                             val_to_str(pd[offset] & SAP_MASK, sap_vals, "%02x"),
 435                             pd[offset] & DSAP_GI_BIT ?
 436                               "Group" : "Individual",
 437                             val_to_str(pd[offset+1] & SAP_MASK, sap_vals, "%02x"),
 438                             pd[offset+1] & SSAP_CR_BIT ?
 439                               "Command" : "Response"
 440                         );
 441                 }
 442
 443                 if (XDLC_HAS_PAYLOAD(control)) {
 444                         /*
 445                          * This frame has a payload to be analyzed.
 446                          */
 447                         dissect = sap_dissect_func(pd[offset]);
 448
 449                         /* non-SNAP */
 450                         offset += llc_header_len;
 451
 452                         if (dissect) {
 453                                 dissect(pd, offset, fd, tree);
 454                         }
 455                         else {
 456                                 dissect_data(pd, offset, fd, tree);
 457                         }
 458                 }
 459         }
 460 }
 461
 462 void
 463 proto_register_llc(void)
 464 {
 465         static struct true_false_string ig_bit = { "Group", "Individual" };
 466         static struct true_false_string cr_bit = { "Response", "Command" };
 467
 468         static hf_register_info hf[] = {
 469                 { &hf_llc_dsap,
 470                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 471                         VALS(sap_vals), 0x0, "" }},
 472
 473                 { &hf_llc_dsap_ig,
 474                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 475                         &ig_bit, 0x0, "Individual/Group" }},
 476
 477                 { &hf_llc_ssap,
 478                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 479                         VALS(sap_vals), 0x0, "" }},
 480
 481                 { &hf_llc_ssap_cr,
 482                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 483                         &cr_bit, 0x0, "Command/Response" }},
 484
 485                 { &hf_llc_ctrl,
 486                 { "Control", "llc.control", FT_UINT8, BASE_HEX,
 487                         VALS(llc_ctrl_vals), 0x0, "" }},
 488
 489                 /* registered here but handled in ethertype.c */
 490                 { &hf_llc_type,
 491                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 492                         VALS(etype_vals), 0x0, "" }},
 493
 494                 { &hf_llc_oui,
 495                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 496                         VALS(oui_vals), 0x0, ""}},
 497
 498                 { &hf_llc_pid,
 499                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 500                         NULL, 0x0, ""}}
 501         };
 502         static gint *ett[] = {
 503                 &ett_llc,
 504                 &ett_llc_ctrl,
 505         };
 506
 507         proto_llc = proto_register_protocol ("Logical-Link Control", "llc" );
 508         proto_register_field_array(proto_llc, hf, array_length(hf));
 509         proto_register_subtree_array(ett, array_length(ett));
 510 }