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 1.44 2000/01/24 02:44:52 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 #define SAP_SNAP        0xAA
  92
  93 /*
  94  * These are for SSAP and DSAP, wth last bit always zero.
  95  * XXX - some DSAPs come in separate "individual" and "group" versions,
  96  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
  97  * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
  98  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
  99  */
 100 static const value_string sap_vals[] = {
 101         { 0x00,     "NULL LSAP" },
 102         { 0x02,     "LLC Sub-Layer Management" },
 103         { 0x04,     "SNA Path Control" },
 104         { 0x06,     "TCP/IP" },
 105         { 0x08,     "SNA" },
 106         { 0x0C,     "SNA" },
 107         { 0x0E,     "PROWAY (IEC955) Network Management and Initialization" },
 108         { 0x18,     "Texas Instruments" },
 109         { 0x42,     "Spanning Tree BPDU" },
 110         { 0x4E,     "EIA RS-511 Manufacturing Message Service" },
 111 #if 0
 112         /* XXX - setting the group bit makes this 0x7F; is that just
 113            a group version of this? */
 114         { 0x7E,     "ISO 8208 (X.25 over 802.2 Type 2)" },
 115 #endif
 116         { 0x7F,     "ISO 802.2" },
 117         { 0x80,     "XNS" },
 118         { 0x86,     "Nestar" },
 119         { 0x8E,     "PROWAY (IEC955) Active Station List Maintenance" },
 120         { 0x98,     "ARP" },    /* XXX - hand to "dissect_arp()"? */
 121         { SAP_SNAP, "SNAP" },
 122         { 0xBA,     "Banyan Vines" },
 123         { 0xBC,     "Banyan Vines" },
 124         { 0xE0,     "NetWare" },
 125         { 0xF0,     "NetBIOS" },
 126         { 0xF4,     "IBM Net Management" },
 127         { 0xF8,     "Remote Program Load" },
 128         { 0xFA,     "Ungermann-Bass" },
 129         { 0xFC,     "Remote Program Load" },
 130         { 0xFE,     "ISO Network Layer" },
 131         { 0xFF,     "Global LSAP" },
 132         { 0x00,     NULL }
 133 };
 134
 135 static struct sap_info  saps[] = {
 136         { 0x00,         NULL,           NULL },
 137         { 0x02,         NULL,           NULL },
 138         { 0x03,         NULL,           NULL },
 139         { 0x04,         NULL,           dissect_sna },
 140         { 0x05,         NULL,           NULL },
 141         { 0x06,         capture_ip,     dissect_ip },
 142         { 0x08,         NULL,           NULL },
 143         { 0x0C,         NULL,           NULL },
 144         { 0x42,         NULL,           dissect_bpdu },
 145         { 0x7F,         NULL,           NULL },
 146         { 0x80,         NULL,           NULL },
 147         { SAP_SNAP,     NULL,           NULL },
 148         { 0xBA,         NULL,           NULL },
 149         { 0xBC,         NULL,           NULL },
 150         { 0xE0,         capture_ipx,    dissect_ipx },
 151         { 0xF0,         capture_netbios, dissect_netbios },
 152         { 0xF4,         NULL,           NULL },
 153         { 0xF5,         NULL,           NULL },
 154         { 0xF8,         NULL,           NULL },
 155         { 0xFC,         NULL,           NULL },
 156         { 0xFE,         NULL,           dissect_osi },
 157         { 0xFF,         NULL,           NULL },
 158         { 0x00,         NULL,           NULL}
 159 };
 160
 161 static const value_string llc_ctrl_vals[] = {
 162         { 0, "Information Transfer" },
 163         { 1, "Supervisory" },
 164         { 2, "Unknown" },
 165         { 3, "Unnumbered Information" },
 166         { 0, NULL }
 167 };
 168
 169 const value_string oui_vals[] = {
 170         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 171 /*
 172 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 173 */
 174         { OUI_CISCO,       "Cisco" },
 175         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 176         { OUI_BFR,         "Bridged Frame-Relay" }, /* RFC 2427 */
 177         { OUI_ATM_FORUM,   "ATM Forum" },
 178         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 179         { 0,               NULL }
 180 };
 181
 182 static capture_func_t *
 183 sap_capture_func(u_char sap) {
 184         int i=0;
 185
 186         /* look for the second record where sap == 0, which should
 187          * be the last record
 188          */
 189         while (saps[i].sap > 0 || i == 0) {
 190                 if (saps[i].sap == sap) {
 191                         return saps[i].capture_func;
 192                 }
 193                 i++;
 194         }
 195         return NULL;
 196 }
 197
 198 static dissect_func_t *
 199 sap_dissect_func(u_char sap) {
 200         int i=0;
 201
 202         /* look for the second record where sap == 0, which should
 203          * be the last record
 204          */
 205         while (saps[i].sap > 0 || i == 0) {
 206                 if (saps[i].sap == sap) {
 207                         return saps[i].dissect_func;
 208                 }
 209                 i++;
 210         }
 211         return dissect_data;
 212 }
 213
 214 void
 215 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
 216
 217         int             is_snap;
 218         guint16         control;
 219         int             llc_header_len;
 220         guint32         oui;
 221         guint16         etype;
 222         capture_func_t  *capture;
 223
 224         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 225                 ld->other++;
 226                 return;
 227         }
 228         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 229         llc_header_len = 2;     /* DSAP + SSAP */
 230
 231         /*
 232          * XXX - the page referred to in the comment above about the
 233          * Command/Response bit also implies that LLC Type 2 always
 234          * uses extended operation, so we don't need to determine
 235          * whether it's basic or extended operation; is that the case?
 236          */
 237         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
 238             TRUE);
 239         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 240         if (is_snap)
 241                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 242         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 243                 ld->other++;
 244                 return;
 245         }
 246
 247         if (is_snap) {
 248                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 249                 if (XDLC_IS_INFORMATION(control)) {
 250                         etype = pntohs(&pd[offset+6]);
 251                         switch (oui) {
 252
 253                         case OUI_ENCAP_ETHER:
 254                         case OUI_APPLE_ATALK:
 255                                 /* No, I have no idea why Apple used
 256                                    one of their own OUIs, rather than
 257                                    OUI_ENCAP_ETHER, and an Ethernet
 258                                    packet type as protocol ID, for
 259                                    AppleTalk data packets - but used
 260                                    OUI_ENCAP_ETHER and an Ethernet
 261                                    packet type for AARP packets. */
 262                                 capture_ethertype(etype, offset+8, pd,
 263                                     ld);
 264                                 break;
 265                         case OUI_CISCO:
 266                                 capture_ethertype(etype,
 267                                                 offset + 8, pd, ld);
 268                                 break;
 269                         default:
 270                                 ld->other++;
 271                                 break;
 272                         }
 273                 }
 274         }
 275         else {
 276                 if (XDLC_IS_INFORMATION(control)) {
 277                         capture = sap_capture_func(pd[offset]);
 278
 279                         /* non-SNAP */
 280                         offset += llc_header_len;
 281
 282                         if (capture) {
 283                                 capture(pd, offset, ld);
 284                         }
 285                         else {
 286                                 ld->other++;
 287                         }
 288                 }
 289         }
 290 }
 291
 292 void
 293 dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
 294
 295         proto_tree      *llc_tree = NULL;
 296         proto_item      *ti = NULL;
 297         int             is_snap;
 298         guint16         control;
 299         int             llc_header_len;
 300         guint32         oui;
 301         guint16         etype;
 302         dissect_func_t  *dissect;
 303
 304         if (!BYTES_ARE_IN_FRAME(offset, 2)) {
 305                 dissect_data(pd, offset, fd, tree);
 306                 return;
 307         }
 308         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 309         llc_header_len = 2;     /* DSAP + SSAP */
 310
 311         if (check_col(fd, COL_PROTOCOL)) {
 312                 col_add_str(fd, COL_PROTOCOL, "LLC");
 313         }
 314
 315         if (tree) {
 316                 ti = proto_tree_add_item(tree, proto_llc, offset, 0, NULL);
 317                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 318                 proto_tree_add_item(llc_tree, hf_llc_dsap, offset,
 319                         1, pd[offset] & SAP_MASK);
 320                 proto_tree_add_item(llc_tree, hf_llc_dsap_ig, offset,
 321                         1, pd[offset] & DSAP_GI_BIT);
 322                 proto_tree_add_item(llc_tree, hf_llc_ssap, offset+1,
 323                         1, pd[offset+1] & SAP_MASK);
 324                 proto_tree_add_item(llc_tree, hf_llc_ssap_cr, offset+1,
 325                         1, pd[offset+1] & SSAP_CR_BIT);
 326         } else
 327                 llc_tree = NULL;
 328
 329         /*
 330          * XXX - the page referred to in the comment above about the
 331          * Command/Response bit also implies that LLC Type 2 always
 332          * uses extended operation, so we don't need to determine
 333          * whether it's basic or extended operation; is that the case?
 334          */
 335         control = dissect_xdlc_control(pd, offset+2, fd, llc_tree,
 336                                 hf_llc_ctrl, ett_llc_ctrl,
 337                                 pd[offset+1] & SSAP_CR_BIT, TRUE);
 338         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 339         if (is_snap)
 340                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 341         if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
 342                 dissect_data(pd, offset, fd, tree);
 343                 return;
 344         }
 345         if (tree)
 346                 proto_item_set_len(ti, llc_header_len);
 347
 348         /*
 349          * XXX - do we want to append the SAP information to the stuff
 350          * "dissect_xdlc_control()" put in the COL_INFO column, rather
 351          * than overwriting it?
 352          */
 353         if (is_snap) {
 354                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 355                 etype = pntohs(&pd[offset+6]);
 356                 if (check_col(fd, COL_INFO)) {
 357                         col_add_fstr(fd, COL_INFO, "SNAP, OUI 0x%06X (%s), PID 0x%04X",
 358                             oui, val_to_str(oui, oui_vals, "Unknown"),
 359                             etype);
 360                 }
 361                 if (tree) {
 362                         proto_tree_add_item(llc_tree, hf_llc_oui, offset+3, 3,
 363                                 oui);
 364                 }
 365                 switch (oui) {
 366
 367                 case OUI_ENCAP_ETHER:
 368                 case OUI_APPLE_ATALK:
 369                         /* No, I have no idea why Apple used
 370                            one of their own OUIs, rather than
 371                            OUI_ENCAP_ETHER, and an Ethernet
 372                            packet type as protocol ID, for
 373                            AppleTalk data packets - but used
 374                            OUI_ENCAP_ETHER and an Ethernet
 375                            packet type for AARP packets. */
 376                         if (XDLC_IS_INFORMATION(control)) {
 377                                 ethertype(etype, offset+8, pd,
 378                                     fd, tree, llc_tree, hf_llc_type);
 379                         } else
 380                                 dissect_data(pd, offset+8, fd, tree);
 381                         break;
 382
 383                 case OUI_CISCO:
 384                         /* So are all CDP packets LLC packets
 385                            with an OUI of OUI_CISCO and a
 386                            protocol ID of 0x2000, or
 387                            are some of them raw or encapsulated
 388                            Ethernet? */
 389                         if (tree) {
 390                                 proto_tree_add_item(llc_tree,
 391                                     hf_llc_pid, offset+6, 2, etype);
 392                         }
 393                         if (XDLC_IS_INFORMATION(control)) {
 394                                 switch (etype) {
 395
 396                                 case 0x2000:
 397                                         dissect_cdp(pd, offset+8, fd, tree);
 398                                         break;
 399
 400                                 default:
 401                                         dissect_data(pd, offset+8, fd, tree);
 402                                         break;
 403                                 }
 404                         } else
 405                                 dissect_data(pd, offset+8, fd, tree);
 406                         break;
 407
 408                 default:
 409                         if (tree) {
 410                                 proto_tree_add_item(llc_tree,
 411                                     hf_llc_pid, offset+6, 2, etype);
 412                         }
 413                         dissect_data(pd, offset+8, fd, tree);
 414                         break;
 415                 }
 416         }
 417         else {
 418                 if (check_col(fd, COL_INFO)) {
 419                         col_add_fstr(fd, COL_INFO,
 420                             "DSAP %s %s, SSAP %s %s",
 421                             val_to_str(pd[offset] & SAP_MASK, sap_vals, "%02x"),
 422                             pd[offset] & DSAP_GI_BIT ?
 423                               "Group" : "Individual",
 424                             val_to_str(pd[offset+1] & SAP_MASK, sap_vals, "%02x"),
 425                             pd[offset+1] & SSAP_CR_BIT ?
 426                               "Command" : "Response"
 427                         );
 428                 }
 429
 430                 if (XDLC_IS_INFORMATION(control)) {
 431                         dissect = sap_dissect_func(pd[offset]);
 432
 433                         /* non-SNAP */
 434                         offset += llc_header_len;
 435
 436                         if (dissect) {
 437                                 dissect(pd, offset, fd, tree);
 438                         }
 439                         else {
 440                                 dissect_data(pd, offset, fd, tree);
 441                         }
 442                 } else
 443                         dissect_data(pd, offset, fd, tree);
 444         }
 445 }
 446
 447 void
 448 proto_register_llc(void)
 449 {
 450         static struct true_false_string ig_bit = { "Group", "Individual" };
 451         static struct true_false_string cr_bit = { "Response", "Command" };
 452
 453         static hf_register_info hf[] = {
 454                 { &hf_llc_dsap,
 455                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 456                         VALS(sap_vals), 0x0, "" }},
 457
 458                 { &hf_llc_dsap_ig,
 459                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 460                         &ig_bit, 0x0, "Individual/Group" }},
 461
 462                 { &hf_llc_ssap,
 463                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 464                         VALS(sap_vals), 0x0, "" }},
 465
 466                 { &hf_llc_ssap_cr,
 467                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 468                         &cr_bit, 0x0, "Command/Response" }},
 469
 470                 { &hf_llc_ctrl,
 471                 { "Control", "llc.control", FT_UINT8, BASE_HEX,
 472                         VALS(llc_ctrl_vals), 0x0, "" }},
 473
 474                 /* registered here but handled in ethertype.c */
 475                 { &hf_llc_type,
 476                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 477                         VALS(etype_vals), 0x0, "" }},
 478
 479                 { &hf_llc_oui,
 480                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 481                         VALS(oui_vals), 0x0, ""}},
 482
 483                 { &hf_llc_pid,
 484                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 485                         NULL, 0x0, ""}}
 486         };
 487         static gint *ett[] = {
 488                 &ett_llc,
 489                 &ett_llc_ctrl,
 490         };
 491
 492         proto_llc = proto_register_protocol ("Logical-Link Control", "llc" );
 493         proto_register_field_array(proto_llc, hf, array_length(hf));
 494         proto_register_subtree_array(ett, array_length(ett));
 495 }