epan/xdlc.c

   1 /* xdlc.c
   2  * Routines for use by various SDLC-derived protocols, such as HDLC
   3  * and its derivatives LAPB, IEEE 802.2 LLC, etc..
   4  *
   5  * $Id$
   6  *
   7  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; either version 2
  14  * of the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  24  */
  25
  26 #include "config.h"
  27
  28 #include <stdio.h>
  29 #include <string.h>
  30
  31 #include <glib.h>
  32 #include <epan/packet.h>
  33 #include <epan/xdlc.h>
  34 #include <epan/emem.h>
  35 #include <wsutil/pint.h>
  36
  37 const value_string ftype_vals[] = {
  38     { XDLC_I, "Information frame" },
  39     { XDLC_S, "Supervisory frame" },
  40     { XDLC_U, "Unnumbered frame" },
  41     { 0,      NULL }
  42 };
  43
  44 const value_string stype_vals[] = {
  45     { XDLC_RR>>2,   "Receiver ready" },
  46     { XDLC_RNR>>2,  "Receiver not ready" },
  47     { XDLC_REJ>>2,  "Reject" },
  48     { XDLC_SREJ>>2, "Selective reject" },
  49     { 0,            NULL }
  50 };
  51
  52 static const value_string modifier_short_vals_cmd[] = {
  53     { XDLC_UI,    "UI" },
  54     { XDLC_UP,    "UP" },
  55     { XDLC_DISC,  "DISC" },
  56     { XDLC_UA,    "UA" },
  57     { XDLC_SNRM,  "SNRM" },
  58     { XDLC_SNRME, "SNRME" },
  59     { XDLC_TEST,  "TEST" },
  60     { XDLC_SIM,   "SIM" },
  61     { XDLC_FRMR,  "FRMR" },
  62     { XDLC_CFGR,  "CFGR" },
  63     { XDLC_SARM,  "SARM" },
  64     { XDLC_SABM,  "SABM" },
  65     { XDLC_SARME, "SARME" },
  66     { XDLC_SABME, "SABME" },
  67     { XDLC_RESET, "RESET" },
  68     { XDLC_XID,   "XID" },
  69     { XDLC_SNRME, "SNRME" },
  70     { XDLC_BCN,   "BCN" },
  71     { 0,          NULL }
  72 };
  73
  74 const value_string modifier_vals_cmd[] = {
  75     { XDLC_UI>>2,    "Unnumbered Information" },
  76     { XDLC_UP>>2,    "Unnumbered Poll" },
  77     { XDLC_DISC>>2,  "Disconnect" },
  78     { XDLC_UA>>2,    "Unnumbered Acknowledge" },
  79     { XDLC_SNRM>>2,  "Set Normal Response Mode" },
  80     { XDLC_TEST>>2,  "Test" },
  81     { XDLC_SIM>>2,   "Set Initialization Mode" },
  82     { XDLC_FRMR>>2,  "Frame reject" },
  83     { XDLC_CFGR>>2,  "Configure" },
  84     { XDLC_SARM>>2,  "Set Asynchronous Response Mode" },
  85     { XDLC_SABM>>2,  "Set Asynchronous Balanced Mode" },
  86     { XDLC_SARME>>2, "Set Asynchronous Response Mode Extended" },
  87     { XDLC_SABME>>2, "Set Asynchronous Balanced Mode Extended" },
  88     { XDLC_RESET>>2, "Reset" },
  89     { XDLC_XID>>2,   "Exchange identification" },
  90     { XDLC_SNRME>>2, "Set Normal Response Mode Extended" },
  91     { XDLC_BCN>>2,   "Beacon" },
  92     { 0,             NULL }
  93 };
  94
  95 static const value_string modifier_short_vals_resp[] = {
  96     { XDLC_UI,    "UI" },
  97     { XDLC_UP,    "UP" },
  98     { XDLC_RD,    "RD" },
  99     { XDLC_UA,    "UA" },
 100     { XDLC_SNRM,  "SNRM" },
 101     { XDLC_TEST,  "TEST" },
 102     { XDLC_RIM,   "RIM" },
 103     { XDLC_FRMR,  "FRMR" },
 104     { XDLC_CFGR,  "CFGR" },
 105     { XDLC_DM,    "DM" },
 106     { XDLC_SABM,  "SABM" },
 107     { XDLC_SARME, "SARME" },
 108     { XDLC_SABME, "SABME" },
 109     { XDLC_RESET, "RESET" },
 110     { XDLC_XID,   "XID" },
 111     { XDLC_SNRME, "SNRME" },
 112     { XDLC_BCN,   "BCN" },
 113     { 0,          NULL }
 114 };
 115
 116 const value_string modifier_vals_resp[] = {
 117     { XDLC_UI>>2,    "Unnumbered Information" },
 118     { XDLC_UP>>2,    "Unnumbered Poll" },
 119     { XDLC_RD>>2,    "Request Disconnect" },
 120     { XDLC_UA>>2,    "Unnumbered Acknowledge" },
 121     { XDLC_SNRM>>2,  "Set Normal Response Mode" },
 122     { XDLC_TEST>>2,  "Test" },
 123     { XDLC_RIM>>2,   "Request Initialization Mode" },
 124     { XDLC_FRMR>>2,  "Frame reject" },
 125     { XDLC_CFGR>>2,  "Configure" },
 126     { XDLC_DM>>2,    "Disconnected mode" },
 127     { XDLC_SABM>>2,  "Set Asynchronous Balanced Mode" },
 128     { XDLC_SARME>>2, "Set Asynchronous Response Mode Extended" },
 129     { XDLC_SABME>>2, "Set Asynchronous Balanced Mode Extended" },
 130     { XDLC_RESET>>2, "Reset" },
 131     { XDLC_XID>>2,   "Exchange identification" },
 132     { XDLC_SNRME>>2, "Set Normal Response Mode Extended" },
 133     { XDLC_BCN>>2,   "Beacon" },
 134     { 0,             NULL }
 135 };
 136
 137 int
 138 get_xdlc_control(const guchar *pd, int offset, gboolean is_extended)
 139 {
 140     guint16 control;
 141
 142     switch (pd[offset] & 0x03) {
 143
 144     case XDLC_S:
 145     default:
 146         /*
 147          * Supervisory or Information frame.
 148          */
 149         if (is_extended)
 150                 control = pletohs(&pd[offset]);
 151         else
 152                 control = pd[offset];
 153         break;
 154
 155     case XDLC_U:
 156         /*
 157          * Unnumbered frame.
 158          *
 159          * XXX - is this two octets, with a P/F bit, in HDLC extended
 160          * operation?  It's one octet in LLC, even though the control
 161          * field of I and S frames is a 2-byte extended-operation field
 162          * in LLC.  Given that there are no sequence numbers in the
 163          * control field of a U frame, there doesn't appear to be any
 164          * need for it to be 2 bytes in extended operation.
 165          */
 166         control = pd[offset];
 167         break;
 168     }
 169     return control;
 170 }
 171
 172 /*
 173  * Check whether the control field of the packet looks valid.
 174  */
 175 gboolean
 176 check_xdlc_control(tvbuff_t *tvb, int offset,
 177   const value_string *u_modifier_short_vals_cmd,
 178   const value_string *u_modifier_short_vals_resp, gboolean is_response,
 179   gboolean is_extended _U_)
 180 {
 181     guint16 control;
 182
 183     if (!tvb_bytes_exist(tvb, offset, 1))
 184         return FALSE;   /* not enough data to check */
 185     switch (tvb_get_guint8(tvb, offset) & 0x03) {
 186
 187     case XDLC_S:
 188         /*
 189          * Supervisory frame.
 190          * No fields to check for validity here.
 191          */
 192         return TRUE;
 193
 194     case XDLC_U:
 195         /*
 196          * Unnumbered frame.
 197          *
 198          * XXX - is this two octets, with a P/F bit, in HDLC extended
 199          * operation?  It's one octet in LLC, even though the control
 200          * field of I and S frames is a 2-byte extended-operation field
 201          * in LLC.  Given that there are no sequence numbers in the
 202          * control field of a U frame, there doesn't appear to be any
 203          * need for it to be 2 bytes in extended operation.
 204          */
 205         if (u_modifier_short_vals_cmd == NULL)
 206                 u_modifier_short_vals_cmd = modifier_short_vals_cmd;
 207         if (u_modifier_short_vals_resp == NULL)
 208                 u_modifier_short_vals_resp = modifier_short_vals_resp;
 209         control = tvb_get_guint8(tvb, offset);
 210         if (is_response) {
 211                 if (try_val_to_str(control & XDLC_U_MODIFIER_MASK,
 212                     u_modifier_short_vals_resp) == NULL)
 213                         return FALSE;   /* unknown modifier */
 214         } else {
 215                 if (try_val_to_str(control & XDLC_U_MODIFIER_MASK,
 216                     u_modifier_short_vals_cmd) == NULL)
 217                         return FALSE;   /* unknown modifier */
 218         }
 219         return TRUE;
 220
 221     default:
 222         /*
 223          * Information frame.
 224          * No fields to check for validity here.
 225          */
 226         return TRUE;
 227     }
 228 }
 229
 230 int
 231 dissect_xdlc_control(tvbuff_t *tvb, int offset, packet_info *pinfo,
 232   proto_tree *xdlc_tree, int hf_xdlc_control, gint ett_xdlc_control,
 233   const xdlc_cf_items *cf_items_nonext, const xdlc_cf_items *cf_items_ext,
 234   const value_string *u_modifier_short_vals_cmd,
 235   const value_string *u_modifier_short_vals_resp, gboolean is_response,
 236   gboolean is_extended, gboolean append_info)
 237 {
 238     guint16 control;
 239     int control_len;
 240     const xdlc_cf_items *cf_items;
 241     const char *control_format;
 242     guint16 poll_final;
 243     char *info;
 244     proto_tree *tc, *control_tree;
 245     const gchar *frame_type = NULL;
 246     const gchar *modifier;
 247
 248     info=(char *)ep_alloc(80);
 249     switch (tvb_get_guint8(tvb, offset) & 0x03) {
 250
 251     case XDLC_S:
 252         /*
 253          * Supervisory frame.
 254          */
 255         if (is_extended) {
 256             control = tvb_get_letohs(tvb, offset);
 257             control_len = 2;
 258             cf_items = cf_items_ext;
 259             control_format = "Control field: %s (0x%04X)";
 260         } else {
 261             control = tvb_get_guint8(tvb, offset);
 262             control_len = 1;
 263             cf_items = cf_items_nonext;
 264             control_format = "Control field: %s (0x%02X)";
 265         }
 266         switch (control & XDLC_S_FTYPE_MASK) {
 267         case XDLC_RR:
 268             frame_type = "RR";
 269             break;
 270
 271         case XDLC_RNR:
 272             frame_type = "RNR";
 273             break;
 274
 275         case XDLC_REJ:
 276             frame_type = "REJ";
 277             break;
 278
 279         case XDLC_SREJ:
 280             frame_type = "SREJ";
 281             break;
 282         }
 283         if (is_extended) {
 284             poll_final = (control & XDLC_P_F_EXT);
 285             g_snprintf(info, 80, "S%s, func=%s, N(R)=%u",
 286                         (poll_final ?
 287                             (is_response ? " F" : " P") :
 288                             ""),
 289                         frame_type,
 290                         (control & XDLC_N_R_EXT_MASK) >> XDLC_N_R_EXT_SHIFT);
 291         } else {
 292             poll_final = (control & XDLC_P_F);
 293             g_snprintf(info, 80, "S%s, func=%s, N(R)=%u",
 294                         (poll_final ?
 295                             (is_response ? " F" : " P") :
 296                             ""),
 297                         frame_type,
 298                         (control & XDLC_N_R_MASK) >> XDLC_N_R_SHIFT);
 299         }
 300         if (append_info) {
 301             col_append_str(pinfo->cinfo, COL_INFO, ", ");
 302             col_append_str(pinfo->cinfo, COL_INFO, info);
 303         } else {
 304             col_add_str(pinfo->cinfo, COL_INFO, info);
 305         }
 306         if (xdlc_tree) {
 307             tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb,
 308                 offset, control_len, control, control_format, info, control);
 309             control_tree = proto_item_add_subtree(tc, ett_xdlc_control);
 310             proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_r,
 311                 tvb, offset, control_len, control);
 312             if (poll_final) {
 313                 proto_tree_add_boolean(control_tree,
 314                         (is_response ? *cf_items->hf_xdlc_f :
 315                                        *cf_items->hf_xdlc_p),
 316                         tvb, offset, control_len, control);
 317             }
 318             proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_s_ftype,
 319                 tvb, offset, control_len, control);
 320             /* This will always say it's a supervisory frame */
 321             proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_s_u,
 322                 tvb, offset, control_len, control);
 323         }
 324         break;
 325
 326     case XDLC_U:
 327         /*
 328          * Unnumbered frame.
 329          *
 330          * XXX - is this two octets, with a P/F bit, in HDLC extended
 331          * operation?  It's one octet in LLC, even though the control
 332          * field of I and S frames is a 2-byte extended-operation field
 333          * in LLC.  Given that there are no sequence numbers in the
 334          * control field of a U frame, there doesn't appear to be any
 335          * need for it to be 2 bytes in extended operation.
 336          */
 337         if (u_modifier_short_vals_cmd == NULL)
 338                 u_modifier_short_vals_cmd = modifier_short_vals_cmd;
 339         if (u_modifier_short_vals_resp == NULL)
 340                 u_modifier_short_vals_resp = modifier_short_vals_resp;
 341         control = tvb_get_guint8(tvb, offset);
 342         control_len = 1;
 343         cf_items = cf_items_nonext;
 344         control_format = "Control field: %s (0x%02X)";
 345         if (is_response) {
 346                 modifier = val_to_str(control & XDLC_U_MODIFIER_MASK,
 347                         u_modifier_short_vals_resp, "Unknown");
 348         } else {
 349                 modifier = val_to_str(control & XDLC_U_MODIFIER_MASK,
 350                         u_modifier_short_vals_cmd, "Unknown");
 351         }
 352         poll_final = (control & XDLC_P_F);
 353         g_snprintf(info, 80, "U%s, func=%s",
 354                 (poll_final ?
 355                     (is_response ? " F" : " P") :
 356                     ""),
 357                 modifier);
 358         if (append_info) {
 359             col_append_str(pinfo->cinfo, COL_INFO, ", ");
 360         col_append_str(pinfo->cinfo, COL_INFO, info);
 361         } else {
 362             col_add_str(pinfo->cinfo, COL_INFO, info);
 363         }
 364         if (xdlc_tree) {
 365             tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb,
 366                 offset, control_len, control, control_format, info, control);
 367             control_tree = proto_item_add_subtree(tc, ett_xdlc_control);
 368             if (poll_final) {
 369                 proto_tree_add_boolean(control_tree,
 370                         (is_response ? *cf_items->hf_xdlc_f:
 371                                        *cf_items->hf_xdlc_p),
 372                         tvb, offset, control_len, control);
 373             }
 374             proto_tree_add_uint(control_tree,
 375                 (is_response ? *cf_items->hf_xdlc_u_modifier_resp :
 376                                *cf_items->hf_xdlc_u_modifier_cmd),
 377                 tvb, offset, control_len, control);
 378             /* This will always say it's an unnumbered frame */
 379             proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_s_u,
 380                 tvb, offset, control_len, control);
 381         }
 382         break;
 383
 384     default:
 385         /*
 386          * Information frame.
 387          */
 388         if (is_extended) {
 389             control = tvb_get_letohs(tvb, offset);
 390             control_len = 2;
 391             cf_items = cf_items_ext;
 392             control_format = "Control field: %s (0x%04X)";
 393             poll_final = (control & XDLC_P_F_EXT);
 394             g_snprintf(info, 80, "I%s, N(R)=%u, N(S)=%u",
 395                         ((control & XDLC_P_F_EXT) ? " P" : ""),
 396                         (control & XDLC_N_R_EXT_MASK) >> XDLC_N_R_EXT_SHIFT,
 397                         (control & XDLC_N_S_EXT_MASK) >> XDLC_N_S_EXT_SHIFT);
 398         } else {
 399             control = tvb_get_guint8(tvb, offset);
 400             control_len = 1;
 401             cf_items = cf_items_nonext;
 402             control_format = "Control field: %s (0x%02X)";
 403             poll_final = (control & XDLC_P_F);
 404             g_snprintf(info, 80, "I%s, N(R)=%u, N(S)=%u",
 405                         ((control & XDLC_P_F) ? " P" : ""),
 406                         (control & XDLC_N_R_MASK) >> XDLC_N_R_SHIFT,
 407                         (control & XDLC_N_S_MASK) >> XDLC_N_S_SHIFT);
 408         }
 409         if (append_info) {
 410             col_append_str(pinfo->cinfo, COL_INFO, ", ");
 411         col_append_str(pinfo->cinfo, COL_INFO, info);
 412         } else {
 413             col_add_str(pinfo->cinfo, COL_INFO, info);
 414         }
 415         if (xdlc_tree) {
 416             tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb,
 417                 offset, control_len, control, control_format, info, control);
 418             control_tree = proto_item_add_subtree(tc, ett_xdlc_control);
 419             proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_r,
 420                 tvb, offset, control_len, control);
 421             proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_s,
 422                 tvb, offset, control_len, control);
 423             if (poll_final) {
 424                 proto_tree_add_boolean(control_tree, *cf_items->hf_xdlc_p,
 425                         tvb, offset, control_len, control);
 426             }
 427             /* This will always say it's an information frame */
 428             proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_i,
 429                 tvb, offset, control_len, control);
 430         }
 431         break;
 432     }
 433     return control;
 434 }