packet-lapb.c

   1 /* packet-lapb.c
   2  * Routines for lapb frame disassembly
   3  * Olivier Abad <abad@daba.dhis.org>
   4  *
   5  * Ethereal - Network traffic analyzer
   6  * By Gerald Combs <gerald@zing.org>
   7  * Copyright 1998
   8  *
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  23  */
  24
  25 #ifdef HAVE_CONFIG_H
  26 # include "config.h"
  27 #endif
  28
  29 #ifdef HAVE_SYS_TYPES_H
  30 # include <sys/types.h>
  31 #endif
  32
  33 #include <stdio.h>
  34 #include <glib.h>
  35 #include <string.h>
  36 #include "packet.h"
  37
  38 #define LAPB_I          0x00    /* Information frames */
  39 #define LAPB_S          0x01    /* Supervisory frames */
  40 #define LAPB_U          0x03    /* Unnumbered frames */
  41
  42 #define LAPB_RR         0x01    /* Receiver ready */
  43 #define LAPB_RNR        0x05    /* Receiver not ready */
  44 #define LAPB_REJ        0x09    /* Reject */
  45 #define LAPB_SABM       0x2F    /* Set Asynchronous Balanced Mode */
  46 #define LAPB_SABME      0x6F    /* Set Asynchronous Balanced Mode Extended */
  47 #define LAPB_DISC       0x43    /* Disconnect */
  48 #define LAPB_DM         0x0F    /* Disconnected mode */
  49 #define LAPB_UA         0x63    /* Unnumbered acknowledge */
  50 #define LAPB_FRMR       0x87    /* Frame reject */
  51
  52 #define FROM_DCE        0x80
  53
  54 int proto_lapb = -1;
  55 int hf_lapb_address = -1;
  56 int hf_lapb_control = -1;
  57
  58 void
  59 dissect_lapb(const u_char *pd, frame_data *fd, proto_tree *tree)
  60 {
  61     proto_tree *lapb_tree, *ti;
  62     char lapb_addr[3];
  63     char info[80];
  64
  65     if (check_col(fd, COL_PROTOCOL))
  66         col_add_str(fd, COL_PROTOCOL, "LAPB");
  67
  68     sprintf(lapb_addr, "%2d", (int)pd[0]);
  69     if(check_col(fd, COL_RES_DL_SRC))
  70         col_add_str(fd, COL_RES_DL_SRC, lapb_addr);
  71
  72     switch (pd[1] & 0x0F) {
  73     case LAPB_RR:
  74         if(check_col(fd, COL_INFO)) {
  75             sprintf(info, "RR N(R):%d", (pd[1] >> 5) & 0x7);
  76             if ((pd[1] >> 4) && 0x01) { /* P/F bit */
  77                 if (((fd->flags & FROM_DCE) && pd[0] == 0x01) ||
  78                     (!(fd->flags & FROM_DCE) && pd[0] == 0x03))
  79                     strcat(info, " F");
  80                 else
  81                     strcat(info, " P");
  82             }
  83             col_add_str(fd, COL_INFO, info);
  84         }
  85         if (fd->flags & FROM_DCE) {
  86             if(check_col(fd, COL_RES_DL_DST))
  87                 col_add_str(fd, COL_RES_DL_DST, "DTE");
  88             if(check_col(fd, COL_RES_DL_SRC))
  89                 col_add_str(fd, COL_RES_DL_SRC, "DCE");
  90         }
  91         else {
  92             if(check_col(fd, COL_RES_DL_DST))
  93                 col_add_str(fd, COL_RES_DL_DST, "DCE");
  94             if(check_col(fd, COL_RES_DL_SRC))
  95                 col_add_str(fd, COL_RES_DL_SRC, "DTE");
  96         }
  97         if (tree)
  98         {
  99             ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 100                                             "LAPB");
 101             lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 102             proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1, pd[0],
 103                                        "Address : 0x%02X", (int)pd[0]);
 104             proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1, "RR",
 105                                        "Control field : 0x%02X", (int)pd[1]);
 106             proto_tree_add_text(lapb_tree, 1, 1,
 107                                 "     %d%d%d..... : N(R) = %d",
 108                                 (pd[1] >> 7) & 0x1,
 109                                 (pd[1] >> 6) & 0x1,
 110                                 (pd[1] >> 5) & 0x1,
 111                                 (pd[1] >> 5) & 0x7);
 112             proto_tree_add_text(lapb_tree, 1, 1,
 113                                 "     ...%d.... : Poll/Final bit",
 114                                 (pd[1] >> 4) & 0x1);
 115             proto_tree_add_text(lapb_tree, 1, 1,
 116                                 "     ....0001 : Receive Ready (RR)");
 117         }
 118         return;
 119     case LAPB_RNR:
 120         if(check_col(fd, COL_INFO)) {
 121             sprintf(info, "RNR N(R):%d", (pd[1] >> 5) & 0x7);
 122             if ((pd[1] >> 4) && 0x01) { /* P/F bit */
 123                 if (((fd->flags & FROM_DCE) && pd[0] == 0x01) ||
 124                     (!(fd->flags & FROM_DCE) && pd[0] == 0x03))
 125                     strcat(info, " F");
 126                 else
 127                     strcat(info, " P");
 128             }
 129             col_add_str(fd, COL_INFO, info);
 130         }
 131         if (fd->flags & FROM_DCE) {
 132             if(check_col(fd, COL_RES_DL_DST))
 133                 col_add_str(fd, COL_RES_DL_DST, "DTE");
 134             if(check_col(fd, COL_RES_DL_SRC))
 135                 col_add_str(fd, COL_RES_DL_SRC, "DCE");
 136         }
 137         else {
 138             if(check_col(fd, COL_RES_DL_DST))
 139                 col_add_str(fd, COL_RES_DL_DST, "DCE");
 140             if(check_col(fd, COL_RES_DL_SRC))
 141                 col_add_str(fd, COL_RES_DL_SRC, "DTE");
 142         }
 143         if (tree)
 144         {
 145             ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 146                                             "LAPB");
 147             lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 148             proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1, pd[0],
 149                                        "Address : 0x%02X", (int)pd[0]);
 150             proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1, "RNR",
 151                                        "Control field : 0x%02X", (int)pd[1]);
 152             proto_tree_add_text(lapb_tree, 1, 1,
 153                                 "     %d%d%d..... : N(R) = %d",
 154                                 (pd[1] >> 7) & 0x1,
 155                                 (pd[1] >> 6) & 0x1,
 156                                 (pd[1] >> 5) & 0x1,
 157                                 (pd[1] >> 5) & 0x7);
 158             proto_tree_add_text(lapb_tree, 1, 1,
 159                                 "     ...%d.... : Poll/Final bit",
 160                                 (pd[1] >> 4) & 0x1);
 161             proto_tree_add_text(lapb_tree, 1, 1,
 162                                 "     ....0101 : Receive Not Ready (RNR)");
 163         }
 164         return;
 165     case LAPB_REJ:
 166         if(check_col(fd, COL_INFO)) {
 167             sprintf(info, "REJ N(R):%d", (pd[1] >> 5) & 0x7);
 168             if ((pd[1] >> 4) && 0x01) { /* P/F bit */
 169                 if (((fd->flags & FROM_DCE) && pd[0] == 0x01) ||
 170                     (!(fd->flags & FROM_DCE) && pd[0] == 0x03))
 171                     strcat(info, " F");
 172                 else
 173                     strcat(info, " P");
 174             }
 175             col_add_str(fd, COL_INFO, info);
 176         }
 177         if (fd->flags & FROM_DCE) {
 178             if(check_col(fd, COL_RES_DL_DST))
 179                 col_add_str(fd, COL_RES_DL_DST, "DTE");
 180             if(check_col(fd, COL_RES_DL_SRC))
 181                 col_add_str(fd, COL_RES_DL_SRC, "DCE");
 182         }
 183         else {
 184             if(check_col(fd, COL_RES_DL_DST))
 185                 col_add_str(fd, COL_RES_DL_DST, "DCE");
 186             if(check_col(fd, COL_RES_DL_SRC))
 187                 col_add_str(fd, COL_RES_DL_SRC, "DTE");
 188         }
 189         if (tree)
 190         {
 191             ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 192                                             "LAPB");
 193             lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 194             proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1, pd[0],
 195                                        "Address : 0x%02X", (int)pd[0]);
 196             proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1, "REJ",
 197                                        "Control field : 0x%02X", (int)pd[1]);
 198             proto_tree_add_text(lapb_tree, 1, 1,
 199                                 "     %d%d%d..... : N(R) = %d",
 200                                 (pd[1] >> 7) & 0x1,
 201                                 (pd[1] >> 6) & 0x1,
 202                                 (pd[1] >> 5) & 0x1,
 203                                 (pd[1] >> 5) & 0x7);
 204             proto_tree_add_text(lapb_tree, 1, 1,
 205                                 "     ...%d.... : Poll/Final bit",
 206                                 (pd[1] >> 4) & 0x1);
 207             proto_tree_add_text(lapb_tree, 1, 1,
 208                                 "     ....1001 : Reeject (REJ)");
 209         }
 210         return;
 211     }
 212
 213     /* not a RR/RNR/REJ frame */
 214
 215     if (pd[1] & 0x01) { /* not an information frame */
 216         switch (pd[1] & 0xEF) { /* don't check Poll/Final bit */
 217         case LAPB_SABM:
 218             if (fd->flags & FROM_DCE) {
 219                 if(check_col(fd, COL_RES_DL_DST))
 220                     col_add_str(fd, COL_RES_DL_DST, "DTE");
 221                 if(check_col(fd, COL_RES_DL_SRC))
 222                     col_add_str(fd, COL_RES_DL_SRC, "DCE");
 223             }
 224             else {
 225                 if(check_col(fd, COL_RES_DL_DST))
 226                     col_add_str(fd, COL_RES_DL_DST, "DCE");
 227                 if(check_col(fd, COL_RES_DL_SRC))
 228                     col_add_str(fd, COL_RES_DL_SRC, "DTE");
 229             }
 230             if(check_col(fd, COL_INFO)) {
 231                 if (pd[1] & 0x10)
 232                     col_add_str(fd, COL_INFO, "SABM P");
 233                 else
 234                     col_add_str(fd, COL_INFO, "SABM");
 235             }
 236             if (tree) {
 237                 ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 238                                                 "LAPB");
 239                 lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 240                 proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1,
 241                                            pd[0], "Address: 0x%02X",
 242                                            (int)pd[0]);
 243                 proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1,
 244                                            "SABM",
 245                                            "Set Asynchronous Balanced Mode (SABM)");
 246                 proto_tree_add_text(lapb_tree, 1, 1,
 247                                     "...%d.... : Poll bit",
 248                                     (pd[1] >> 4) & 0x1);
 249             }
 250             break;
 251         case LAPB_DISC:
 252             if (fd->flags & FROM_DCE) {
 253                 if(check_col(fd, COL_RES_DL_DST))
 254                     col_add_str(fd, COL_RES_DL_DST, "DTE");
 255                 if(check_col(fd, COL_RES_DL_SRC))
 256                     col_add_str(fd, COL_RES_DL_SRC, "DCE");
 257             }
 258             else {
 259                 if(check_col(fd, COL_RES_DL_DST))
 260                     col_add_str(fd, COL_RES_DL_DST, "DCE");
 261                 if(check_col(fd, COL_RES_DL_SRC))
 262                     col_add_str(fd, COL_RES_DL_SRC, "DTE");
 263             }
 264             if(check_col(fd, COL_INFO)) {
 265                 if (pd[1] & 0x10)
 266                     col_add_str(fd, COL_INFO, "DISC P");
 267                 else
 268                     col_add_str(fd, COL_INFO, "DISC");
 269             }
 270             if (tree) {
 271                 ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 272                                                 "LAPB");
 273                 lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 274                 proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1,
 275                                            pd[0], "Address: 0x%02X",
 276                                            (int)pd[0]);
 277                 proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1,
 278                                            "DISC", "Disconnect (DISC)");
 279                 proto_tree_add_text(lapb_tree, 1, 1,
 280                                     "...%d.... : Poll bit",
 281                                     (pd[1] >> 4) & 0x1);
 282             }
 283             break;
 284         case LAPB_DM:
 285             if (fd->flags & FROM_DCE) {
 286                 if(check_col(fd, COL_RES_DL_DST))
 287                     col_add_str(fd, COL_RES_DL_DST, "DTE");
 288                 if(check_col(fd, COL_RES_DL_SRC))
 289                     col_add_str(fd, COL_RES_DL_SRC, "DCE");
 290             }
 291             else {
 292                 if(check_col(fd, COL_RES_DL_DST))
 293                     col_add_str(fd, COL_RES_DL_DST, "DCE");
 294                 if(check_col(fd, COL_RES_DL_SRC))
 295                     col_add_str(fd, COL_RES_DL_SRC, "DTE");
 296             }
 297             if(check_col(fd, COL_INFO)) {
 298                 if (pd[1] & 0x10)
 299                     col_add_str(fd, COL_INFO, "DM F");
 300                 else
 301                     col_add_str(fd, COL_INFO, "DM");
 302             }
 303             if (tree) {
 304                 ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 305                                                 "LAPB");
 306                 lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 307                 proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1,
 308                                            pd[0], "Address: 0x%02X",
 309                                            (int)pd[0]);
 310                 proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1,
 311                                            "DM", "Disconnect Mode (DM)");
 312                 proto_tree_add_text(lapb_tree, 1, 1,
 313                                     "...%d.... : Final bit",
 314                                     (pd[1] >> 4) & 0x1);
 315             }
 316             break;
 317         case LAPB_UA:
 318             if (fd->flags & FROM_DCE) {
 319                 if(check_col(fd, COL_RES_DL_DST))
 320                     col_add_str(fd, COL_RES_DL_DST, "DTE");
 321                 if(check_col(fd, COL_RES_DL_SRC))
 322                     col_add_str(fd, COL_RES_DL_SRC, "DCE");
 323             }
 324             else {
 325                 if(check_col(fd, COL_RES_DL_DST))
 326                     col_add_str(fd, COL_RES_DL_DST, "DCE");
 327                 if(check_col(fd, COL_RES_DL_SRC))
 328                     col_add_str(fd, COL_RES_DL_SRC, "DTE");
 329             }
 330             if(check_col(fd, COL_INFO)) {
 331                 if (pd[1] & 0x10)
 332                     col_add_str(fd, COL_INFO, "UA F");
 333                 else
 334                     col_add_str(fd, COL_INFO, "UA");
 335             }
 336             if (tree) {
 337                 ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 338                                                 "LAPB");
 339                 lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 340                 proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1,
 341                                            pd[0], "Address: 0x%02X",
 342                                            (int)pd[0]);
 343                 proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1,
 344                                            "UA", "Unnumbered Acknowledge (UA)");
 345                 proto_tree_add_text(lapb_tree, 1, 1,
 346                                     "...%d.... : Final bit",
 347                                     (pd[1] >> 4) & 0x1);
 348             }
 349             break;
 350         case LAPB_FRMR:
 351             if (fd->flags & FROM_DCE) {
 352                 if(check_col(fd, COL_RES_DL_DST))
 353                     col_add_str(fd, COL_RES_DL_DST, "DTE");
 354                 if(check_col(fd, COL_RES_DL_SRC))
 355                     col_add_str(fd, COL_RES_DL_SRC, "DCE");
 356             }
 357             else {
 358                 if(check_col(fd, COL_RES_DL_DST))
 359                     col_add_str(fd, COL_RES_DL_DST, "DCE");
 360                 if(check_col(fd, COL_RES_DL_SRC))
 361                     col_add_str(fd, COL_RES_DL_SRC, "DTE");
 362             }
 363             if(check_col(fd, COL_INFO)) {
 364                 if (pd[1] & 0x10)
 365                     col_add_str(fd, COL_INFO, "FRMR F");
 366                 else
 367                     col_add_str(fd, COL_INFO, "FRMR");
 368             }
 369             if (tree) {
 370                 ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 371                                                 "LAPB");
 372                 lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 373                 proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1,
 374                                            pd[0], "Address: 0x%02X",
 375                                            (int)pd[0]);
 376                 proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1,
 377                                            "FRMR", "Frame Reject (FRMR)");
 378                 proto_tree_add_text(lapb_tree, 1, 1,
 379                                     "...%d.... : Final bit",
 380                                     (pd[1] >> 4) & 0x1);
 381             }
 382             break;
 383         }
 384     }
 385     else /* information frame */
 386     {
 387         if (fd->flags & FROM_DCE) {
 388             if(check_col(fd, COL_RES_DL_DST))
 389                 col_add_str(fd, COL_RES_DL_DST, "DTE");
 390             if(check_col(fd, COL_RES_DL_SRC))
 391                 col_add_str(fd, COL_RES_DL_SRC, "DCE");
 392         }
 393         else {
 394             if(check_col(fd, COL_RES_DL_DST))
 395                 col_add_str(fd, COL_RES_DL_DST, "DCE");
 396             if(check_col(fd, COL_RES_DL_SRC))
 397                 col_add_str(fd, COL_RES_DL_SRC, "DTE");
 398         }
 399         if(check_col(fd, COL_INFO)) {
 400             sprintf(info, "I N(R):%d N(S):%d",
 401                     (pd[1] >> 5) & 0x7,
 402                     (pd[1] >> 1) & 0x7);
 403             if ((pd[1] >> 4) && 0x01) /* P/F bit */
 404                 strcat(info, " P");
 405             col_add_str(fd, COL_INFO, info);
 406         }
 407         if (tree) {
 408             ti = proto_tree_add_item_format(tree, proto_lapb, 0, 2, NULL,
 409                                             "LAPB");
 410             lapb_tree = proto_item_add_subtree(ti, ETT_LAPB);
 411             proto_tree_add_item_format(lapb_tree, hf_lapb_address, 0, 1,
 412                                        pd[0], "Address: 0x%02X",
 413                                        (int)pd[0]);
 414             proto_tree_add_item_format(lapb_tree, hf_lapb_control, 1, 1,
 415                                        "I", "Control field : 0x%02X",
 416                                        (int)pd[1]);
 417             proto_tree_add_text(lapb_tree, 1, 1,
 418                                 "     %d%d%d..... : N(R) = %d",
 419                                 (pd[1] >> 7) & 0x1,
 420                                 (pd[1] >> 6) & 0x1,
 421                                 (pd[1] >> 5) & 0x1,
 422                                 (pd[1] >> 5) & 0x7);
 423             proto_tree_add_text(lapb_tree, 1, 1,
 424                                 "     ...%d.... : Poll/Final bit",
 425                                 (pd[1] >> 4) & 0x1);
 426             proto_tree_add_text(lapb_tree, 1, 1,
 427                                 "     ....%d%d%d. : N(S) = %d",
 428                                 (pd[1] >> 3) & 0x1,
 429                                 (pd[1] >> 2) & 0x1,
 430                                 (pd[1] >> 1) & 0x1,
 431                                 (pd[1] >> 1) & 0x7);
 432             proto_tree_add_text(lapb_tree, 1, 1,
 433                                 "     .......0 : Information Transfer (I)");
 434         }
 435     }
 436
 437     /* not end of frame ==> X.25 */
 438     if (fd->cap_len > 2) dissect_x25(pd, 2, fd, tree);
 439 }
 440
 441 void
 442 proto_register_lapb(void)
 443 {
 444     static hf_register_info hf[] = {
 445         { &hf_lapb_address,
 446           { "Address Field", "lapb.address", FT_UINT8, NULL} },
 447         { &hf_lapb_control,
 448           { "Control Field", "lapb.control", FT_STRING, NULL} },
 449     };
 450
 451     proto_lapb = proto_register_protocol ("LAPB", "lapb");
 452     proto_register_field_array (proto_lapb, hf, array_length(hf));
 453 }