packet-q931.c

   1 /* packet-q931.c
   2  * Routines for Q.931 frame disassembly
   3  * Guy Harris <guy@alum.mit.edu>
   4  *
   5  * $Id: packet-q931.c,v 1.21 2000/11/19 08:54:03 guy Exp $
   6  *
   7  * Modified by Andreas Sikkema for possible use with H.323
   8  *
   9  * Ethereal - Network traffic analyzer
  10  * By Gerald Combs <gerald@zing.org>
  11  * Copyright 1998
  12  *
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License
  16  * as published by the Free Software Foundation; either version 2
  17  * of the License, or (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, write to the Free Software
  26  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  27  */
  28
  29 #ifdef HAVE_CONFIG_H
  30 # include "config.h"
  31 #endif
  32
  33 #ifdef HAVE_SYS_TYPES_H
  34 # include <sys/types.h>
  35 #endif
  36
  37 #include <stdio.h>
  38 #include <glib.h>
  39 #include <string.h>
  40 #include "packet.h"
  41 #include "strutil.h"
  42 #include "nlpid.h"
  43 #include "packet-q931.h"
  44
  45 #ifdef H323
  46 #include "packet-tpkt.h"
  47 #include "packet-h225.h"
  48 #endif
  49
  50 /* Q.931 references:
  51  *
  52  * http://www.acacia-net.com/Clarinet/Protocol/q9313svn.htm
  53  * http://www.acacia-net.com/Clarinet/Protocol/q9311sc3.htm
  54  * http://www.acacia-net.com/Clarinet/Protocol/q9317oz7.htm
  55  * http://www.protocols.com/pbook/isdn.htm
  56  * http://freesoft.org/CIE/Topics/126.htm
  57  * http://noc.comstar.ru/miscdocs/ascend-faq-cause-codes.html
  58  * http://www.andrews-arnold.co.uk/isdn/q931cause.html
  59  * http://www.tulatelecom.ru/staff/german/DSSHelp/MessList/InfEl/InfElList.html
  60  */
  61
  62 static int proto_q931 = -1;
  63 static int hf_q931_discriminator = -1;
  64 static int hf_q931_call_ref_len = -1;
  65 static int hf_q931_call_ref = -1;
  66 static int hf_q931_message_type = -1;
  67
  68 static gint ett_q931 = -1;
  69 static gint ett_q931_ie = -1;
  70
  71 /*
  72  * Q.931 message types.
  73  */
  74 #define Q931_ESCAPE             0x00
  75 #define Q931_ALERTING           0x01
  76 #define Q931_CALL_PROCEEDING    0x02
  77 #define Q931_CONNECT            0x07
  78 #define Q931_CONNECT_ACK        0x0F
  79 #define Q931_PROGRESS           0x03
  80 #define Q931_SETUP              0x05
  81 #define Q931_SETUP_ACK          0x0B
  82 #define Q931_HOLD               0x24
  83 #define Q931_HOLD_ACK           0x28
  84 #define Q931_HOLD_REJECT        0x30
  85 #define Q931_RESUME             0x26
  86 #define Q931_RESUME_ACK         0x2E
  87 #define Q931_RESUME_REJECT      0x22
  88 #define Q931_RETRIEVE           0x31
  89 #define Q931_RETRIEVE_ACK       0x33
  90 #define Q931_RETRIEVE_REJECT    0x37
  91 #define Q931_SUSPEND            0x25
  92 #define Q931_SUSPEND_ACK        0x2D
  93 #define Q931_SUSPEND_REJECT     0x21
  94 #define Q931_USER_INFORMATION   0x20
  95 #define Q931_DISCONNECT         0x45
  96 #define Q931_RELEASE            0x4D
  97 #define Q931_RELEASE_COMPLETE   0x5A
  98 #define Q931_RESTART            0x46
  99 #define Q931_RESTART_ACK        0x4E
 100 #define Q931_CONGESTION_CONTROL 0x79
 101 #define Q931_FACILITY           0x62
 102 #define Q931_INFORMATION        0x7B
 103 #define Q931_NOTIFY             0x6E
 104 #define Q931_REGISTER           0x64
 105 #define Q931_SEGMENT            0x60
 106 #define Q931_STATUS             0x7D
 107 #define Q931_STATUS_ENQUIRY     0x75
 108
 109 static const value_string q931_message_type_vals[] = {
 110   { Q931_ESCAPE,                "ESCAPE" },
 111         { Q931_ALERTING,                "ALERTING" },
 112         { Q931_CALL_PROCEEDING,         "CALL PROCEEDING" },
 113         { Q931_CONNECT,                 "CONNECT" },
 114         { Q931_CONNECT_ACK,             "CONNECT ACKNOWLEDGE" },
 115         { Q931_PROGRESS,                "PROGRESS" },
 116         { Q931_SETUP,                   "SETUP" },
 117         { Q931_SETUP_ACK,               "SETUP ACKNOWLEDGE" },
 118         { Q931_HOLD,                    "HOLD" },
 119         { Q931_HOLD_ACK,                "HOLD_ACKNOWLEDGE" },
 120         { Q931_HOLD_REJECT,             "HOLD_REJECT" },
 121         { Q931_RESUME,                  "RESUME" },
 122         { Q931_RESUME_ACK,              "RESUME ACKNOWLEDGE" },
 123         { Q931_RESUME_REJECT,           "RESUME REJECT" },
 124         { Q931_RETRIEVE,                "RETRIEVE" },
 125         { Q931_RETRIEVE_ACK,            "RETRIEVE ACKNOWLEDGE" },
 126         { Q931_RETRIEVE_REJECT,         "RETRIEVE REJECT" },
 127         { Q931_SUSPEND,                 "SUSPEND" },
 128         { Q931_SUSPEND_ACK,             "SUSPEND ACKNOWLEDGE" },
 129         { Q931_SUSPEND_REJECT,          "SUSPEND REJECT" },
 130         { Q931_USER_INFORMATION,        "USER INFORMATION" },
 131         { Q931_DISCONNECT,              "DISCONNECT" },
 132         { Q931_RELEASE,                 "RELEASE" },
 133         { Q931_RELEASE_COMPLETE,        "RELEASE COMPLETE" },
 134         { Q931_RESTART,                 "RESTART" },
 135         { Q931_RESTART_ACK,             "RESTART ACKNOWLEDGE" },
 136         { Q931_CONGESTION_CONTROL,      "CONGESTION CONTROL" },
 137         { Q931_FACILITY,                "FACILITY" },
 138         { Q931_INFORMATION,             "INFORMATION" },
 139         { Q931_NOTIFY,                  "NOTIFY" },
 140         { Q931_REGISTER,                "REGISTER" },
 141         { Q931_SEGMENT,                 "SEGMENT" },
 142         { Q931_STATUS,                  "STATUS" },
 143         { Q931_STATUS_ENQUIRY,          "STATUS ENQUIRY" },
 144         { 0,                            NULL }
 145 };
 146
 147 /*
 148  * Information elements.
 149  */
 150
 151 /*
 152  * Single-octet IEs.
 153  */
 154 #define Q931_IE_SO_IDENTIFIER_MASK      0xf0    /* IE identifier mask */
 155 #define Q931_IE_SO_IDENTIFIER_SHIFT     4       /* IE identifier shift */
 156 #define Q931_IE_SO_IE_MASK              0x0F    /* IE mask */
 157
 158 #define Q931_IE_SHIFT                   0x90
 159 #define Q931_IE_SHIFT_LOCKING           0x08    /* locking shift */
 160 #define Q931_IE_SHIFT_CODESET           0x0F    /* codeset */
 161
 162 #define Q931_IE_MORE_DATA_OR_SEND_COMP  0xA0    /* More Data or Sending Complete */
 163 #define Q931_IE_MORE_DATA               0xA0
 164 #define Q931_IE_SENDING_COMPLETE        0xA1
 165
 166 #define Q931_IE_CONGESTION_LEVEL        0xB0
 167 #define Q931_IE_REPEAT_INDICATOR        0xD0
 168
 169 /*
 170  * Variable-length IEs.
 171  */
 172 #define Q931_IE_VL_EXTENSION            0x80    /* Extension flag */
 173
 174 /*
 175  * Codeset 0 (default).
 176  */
 177 #define Q931_IE_SEGMENTED_MESSAGE       0x00
 178 #define Q931_IE_BEARER_CAPABILITY       0x04
 179 #define Q931_IE_CAUSE                   0x08
 180 #define Q931_IE_CALL_IDENTITY           0x10
 181 #define Q931_IE_CALL_STATE              0x14
 182 #define Q931_IE_CHANNEL_IDENTIFICATION  0x18
 183 #define Q931_IE_FACILITY                0x1C
 184 #define Q931_IE_PROGRESS_INDICATOR      0x1E
 185 #define Q931_IE_NETWORK_SPECIFIC_FACIL  0x20    /* Network Specific Facilities */
 186 #define Q931_IE_NOTIFICATION_INDICATOR  0x27
 187 #define Q931_IE_DISPLAY                 0x28
 188 #define Q931_IE_DATE_TIME               0x29
 189 #define Q931_IE_KEYPAD_FACILITY         0x2C
 190 #define Q931_IE_INFORMATION_REQUEST     0x32
 191 #define Q931_IE_SIGNAL                  0x34
 192 #define Q931_IE_SWITCHHOOK              0x36
 193 #define Q931_IE_FEATURE_ACTIVATION      0x38
 194 #define Q931_IE_FEATURE_INDICATION      0x39
 195 #define Q931_IE_ENDPOINT_IDENTIFIER     0x3B
 196 #define Q931_IE_SERVICE_PROFILE_ID      0x3A
 197 #define Q931_IE_INFORMATION_RATE        0x40
 198 #define Q931_IE_E2E_TRANSIT_DELAY       0x42    /* End-to-end Transit Delay */
 199 #define Q931_IE_TD_SELECTION_AND_INT    0x43    /* Transit Delay Selection and Indication */
 200 #define Q931_IE_PL_BINARY_PARAMETERS    0x44    /* Packet layer binary parameters */
 201 #define Q931_IE_PL_WINDOW_SIZE          0x45    /* Packet layer window size */
 202 #define Q931_IE_PACKET_SIZE             0x46    /* Packet size */
 203 #define Q931_IE_CUG                     0x47    /* Closed user group */
 204 #define Q931_IE_REVERSE_CHARGE_IND      0x4A    /* Reverse charging indication */
 205 #define Q931_IE_CALLING_PARTY_NUMBER    0x6C    /* Calling Party Number */
 206 #define Q931_IE_CALLING_PARTY_SUBADDR   0x6D    /* Calling Party Subaddress */
 207 #define Q931_IE_CALLED_PARTY_NUMBER     0x70    /* Called Party Number */
 208 #define Q931_IE_CALLED_PARTY_SUBADDR    0x71    /* Called Party Subaddress */
 209 #define Q931_IE_REDIRECTING_NUMBER      0x74
 210 #define Q931_IE_REDIRECTION_NUMBER      0x76
 211 #define Q931_IE_TRANSIT_NETWORK_SEL     0x78    /* Transit Network Selection */
 212 #define Q931_IE_RESTART_INDICATOR       0x79
 213 #define Q931_IE_LOW_LAYER_COMPAT        0x7C    /* Low-Layer Compatibility */
 214 #define Q931_IE_HIGH_LAYER_COMPAT       0x7D    /* High-Layer Compatibility */
 215 #define Q931_IE_USER_USER               0x7E    /* User-User */
 216 #define Q931_IE_ESCAPE                  0x7F    /* Escape for extension */
 217
 218 /*
 219  * Codeset 0 ETSI.
 220  */
 221 #define Q931_IE_CONNECTED_NUMBER        0x8C
 222 #define Q931_IE_CONNECTED_SUBADDR       0x8D
 223
 224 /*
 225  * Codeset 5 (National-specific) Belgium.
 226  */
 227 #define Q931_IE_CHARGING_ADVICE         0x1A
 228
 229 /*
 230  * Codeset 5 (National-specific) Bellcore National ISDN.
 231  */
 232 #define Q931_IE_OPERATOR_SYSTEM_ACCESS  0x1D
 233
 234 /*
 235  * Codeset 6 (Network-specific) Belgium.
 236  */
 237 /* 0x1A is Charging Advice, as with Codeset 5 */
 238 #define Q931_IE_REDIRECTING_NUMBER      0x74
 239
 240 /*
 241  * Codeset 6 (Network-specific) FT-Numeris.
 242  */
 243 /* 0x1D is User Capability */
 244
 245 /*
 246  * Codeset 6 (Network-specific) Bellcore National ISDN.
 247  */
 248 #define Q931_IE_REDIRECTING_SUBADDR     0x75    /* Redirecting Subaddress */
 249 /* 0x76 is Redirection Number, but that's also Codeset 0 */
 250 #define Q931_IE_CALL_APPEARANCE         0x7B
 251
 252 static const value_string q931_info_element_vals[] = {
 253         { Q931_IE_SEGMENTED_MESSAGE,            "Segmented message" },
 254         { Q931_IE_BEARER_CAPABILITY,            "Bearer capability" },
 255         { Q931_IE_CAUSE,                        "Cause" },
 256         { Q931_IE_CALL_IDENTITY,                "Call identity" },
 257         { Q931_IE_CALL_STATE,                   "Call state" },
 258         { Q931_IE_CHANNEL_IDENTIFICATION,       "Channel identification" },
 259         { Q931_IE_FACILITY,                     "Facility" },
 260         { Q931_IE_PROGRESS_INDICATOR,           "Progress indicator" },
 261         { Q931_IE_NETWORK_SPECIFIC_FACIL,       "Network specific facilities" },
 262         { Q931_IE_NOTIFICATION_INDICATOR,       "Notification indicator" },
 263         { Q931_IE_DISPLAY,                      "Display" },
 264         { Q931_IE_DATE_TIME,                    "Date/Time" },
 265         { Q931_IE_KEYPAD_FACILITY,              "Keypad facility" },
 266         { Q931_IE_INFORMATION_REQUEST,          "Information request" },
 267         { Q931_IE_SIGNAL,                       "Signal" },
 268         { Q931_IE_SWITCHHOOK,                   "Switchhook" },
 269         { Q931_IE_FEATURE_ACTIVATION,           "Feature activation" },
 270         { Q931_IE_FEATURE_INDICATION,           "Feature Indication" },
 271         { Q931_IE_ENDPOINT_IDENTIFIER,          "Endpoint identifier" },
 272         { Q931_IE_SERVICE_PROFILE_ID,           "Service profile ID" },
 273         { Q931_IE_INFORMATION_RATE,             "Information rate" },
 274         { Q931_IE_E2E_TRANSIT_DELAY,            "End-to-end transit delay" },
 275         { Q931_IE_TD_SELECTION_AND_INT,         "Transit delay selection and indication" },
 276         { Q931_IE_PL_BINARY_PARAMETERS,         "Packet layer binary parameters" },
 277         { Q931_IE_PL_WINDOW_SIZE,               "Packet layer window size" },
 278         { Q931_IE_PACKET_SIZE,                  "Packet size" },
 279         { Q931_IE_CUG,                          "Closed user group" },
 280         { Q931_IE_REVERSE_CHARGE_IND,           "Reverse charging indication" },
 281         { Q931_IE_CALLING_PARTY_NUMBER,         "Calling party number" },
 282         { Q931_IE_CALLING_PARTY_SUBADDR,        "Calling party subaddress" },
 283         { Q931_IE_CALLED_PARTY_NUMBER,          "Called party number" },
 284         { Q931_IE_CALLED_PARTY_SUBADDR,         "Called party subaddress" },
 285         { Q931_IE_REDIRECTING_NUMBER,           "Redirecting number" },
 286         { Q931_IE_REDIRECTION_NUMBER,           "Redirection number" },
 287         { Q931_IE_TRANSIT_NETWORK_SEL,          "Transit network selection" },
 288         { Q931_IE_RESTART_INDICATOR,            "Restart indicator" },
 289         { Q931_IE_LOW_LAYER_COMPAT,             "Low-layer compatibility" },
 290         { Q931_IE_HIGH_LAYER_COMPAT,            "High-layer compatibility" },
 291         { Q931_IE_USER_USER,                    "User-user" },
 292         { Q931_IE_ESCAPE,                       "Escape" },
 293         { Q931_IE_CONNECTED_NUMBER,             "Connected number" },
 294         { Q931_IE_CONNECTED_SUBADDR,            "Connected subaddress" },
 295         { Q931_IE_CHARGING_ADVICE,              "Charging advice" },
 296         { Q931_IE_OPERATOR_SYSTEM_ACCESS,       "Operator system access" },
 297         { Q931_IE_REDIRECTING_NUMBER,           "Redirecting number" },
 298         { Q931_IE_REDIRECTING_SUBADDR,          "Redirecting subaddress" },
 299         { Q931_IE_CALL_APPEARANCE,              "Call appearance" },
 300         { 0,                                    NULL }
 301 };
 302
 303 static const value_string q931_congestion_level_vals[] = {
 304         { 0x0, "Receiver ready" },
 305         { 0xF, "Receiver not ready" },
 306         { 0,   NULL }
 307 };
 308
 309 static const value_string q931_repeat_indication_vals[] = {
 310         { 0x2, "Prioritized list" },
 311         { 0,   NULL }
 312 };
 313
 314 /*
 315  * ITU-standardized coding.
 316  */
 317 #define Q931_ITU_STANDARDIZED_CODING    0x00
 318
 319 /*
 320  * Dissect a Segmented message information element.
 321  */
 322 static void
 323 dissect_q931_segmented_message_ie(tvbuff_t *tvb, int offset, int len,
 324     proto_tree *tree)
 325 {
 326         if (len != 2) {
 327                 proto_tree_add_text(tree, tvb, offset, len,
 328                     "Segmented message: length is %d, should be 2\n", len);
 329                 return;
 330         }
 331         if (tvb_get_guint8(tvb, offset) & 0x80) {
 332                 proto_tree_add_text(tree, tvb, offset, 1,
 333                     "First segment: %u segments remaining",
 334                     tvb_get_guint8(tvb, offset) & 0x7F);
 335         } else {
 336                 proto_tree_add_text(tree, tvb, offset, 1,
 337                     "Not first segment: %u segments remaining",
 338                     tvb_get_guint8(tvb, offset) & 0x7F);
 339         }
 340         proto_tree_add_text(tree, tvb, offset + 1, 1,
 341             "Segmented message type: %u\n", tvb_get_guint8(tvb, offset + 1));
 342 }
 343
 344 /*
 345  * Dissect a Bearer capability or Low-layer compatibility information element.
 346  */
 347 static const value_string q931_bc_coding_standard_vals[] = {
 348         { 0x00, "ITU-T standardized coding" },
 349         { 0x20, "ISO/IEC standard" },
 350         { 0x40, "National standard" },
 351         { 0x60, "Standard defined for this particular network" },
 352         { 0,    NULL }
 353 };
 354
 355 static const value_string q931_information_transfer_capability_vals[] = {
 356         { 0x00, "Speech" },
 357         { 0x08, "Unrestricted digital information" },
 358         { 0x09, "Restricted digital information" },
 359         { 0x10, "3.1 kHz audio" },
 360         { 0x11, "Unrestricted digital information with tones/announcements" },
 361         { 0x18, "Video" },
 362         { 0,    NULL }
 363 };
 364
 365 static const value_string q931_transfer_mode_vals[] = {
 366         { 0x00, "Circuit mode" },
 367         { 0x40, "Packet mode" },
 368         { 0,    NULL }
 369 };
 370
 371 #define Q931_IT_RATE_MULTIRATE  0x18
 372
 373 static const value_string q931_information_transfer_rate_vals[] = {
 374         { 0x00,                         "Packet mode" },
 375         { 0x10,                         "64 kbit/s" },
 376         { 0x11,                         "2 x 64 kbit/s" },
 377         { 0x13,                         "384 kbit/s" },
 378         { 0x15,                         "1536 kbit/s" },
 379         { 0x17,                         "1920 kbit/s" },
 380         { Q931_IT_RATE_MULTIRATE,       "Multirate (64 kbit/s base rate)" },
 381         { 0,                            NULL }
 382 };
 383
 384 static const value_string q931_uil1_vals[] = {
 385         { 0x01, "V.110/I.460/X.30 rate adaption" },
 386         { 0x02, "Recommendation G.711 u-law" },
 387         { 0x03, "Recommendation G.711 A-law" },
 388         { 0x04, "Recommendation G.721 32 kbit/s ADPCM and Recommendation I.460" },
 389         { 0x05, "Recommendation H.221 and H.242" },
 390         { 0x06, "Recommendation H.223 and H.245" },
 391         { 0x07, "Non-ITU-T-standardized rate adaption" },
 392         { 0x08, "V.120 rate adaption" },
 393         { 0x09, "X.31 HDLC flag stuffing" },
 394         { 0,    NULL },
 395 };
 396
 397 static const value_string q931_l1_user_rate_vals[] = {
 398         { 0x00, "Rate indicated by E-bits" },
 399         { 0x01, "0.6 kbit/s" },
 400         { 0x02, "1.2 kbit/s" },
 401         { 0x03, "2.4 kbit/s" },
 402         { 0x04, "3.6 kbit/s" },
 403         { 0x05, "4.8 kbit/s" },
 404         { 0x06, "7.2 kbit/s" },
 405         { 0x07, "8 kbit/s" },
 406         { 0x08, "9.6 kbit/s" },
 407         { 0x09, "14.4 kbit/s" },
 408         { 0x0A, "16 kbit/s" },
 409         { 0x0B, "19.2 kbit/s" },
 410         { 0x0C, "32 kbit/s" },
 411         { 0x0E, "48 kbit/s" },
 412         { 0x0F, "56 kbit/s" },
 413         { 0x10, "64 kbit/s "},
 414         { 0x15, "0.1345 kbit/s" },
 415         { 0x16, "0.100 kbit/s" },
 416         { 0x17, "0.075/1.2 kbit/s" },
 417         { 0x18, "1.2/0.075 kbit/s" },
 418         { 0x19, "0.050 kbit/s" },
 419         { 0x1A, "0.075 kbit/s" },
 420         { 0x1B, "0.110 kbit/s" },
 421         { 0x1C, "0.150 kbit/s" },
 422         { 0x1D, "0.200 kbit/s" },
 423         { 0x1E, "0.300 kbit/s" },
 424         { 0x1F, "12 kbit/s" },
 425         { 0,    NULL }
 426 };
 427
 428 static const value_string q931_l1_intermediate_rate_vals[] = {
 429         { 0x20, "8 kbit/s" },
 430         { 0x40, "16 kbit/s" },
 431         { 0x60, "32 kbit/s" },
 432         { 0,    NULL }
 433 };
 434
 435 static const value_string q931_l1_stop_bits_vals[] = {
 436         { 0x20, "1" },
 437         { 0x40, "1.5" },
 438         { 0x60, "2" },
 439         { 0,    NULL }
 440 };
 441
 442 static const value_string q931_l1_data_bits_vals[] = {
 443         { 0x08, "5" },
 444         { 0x10, "7" },
 445         { 0x18, "8" },
 446         { 0,    NULL }
 447 };
 448
 449 static const value_string q931_l1_parity_vals[] = {
 450         { 0x00, "Odd" },
 451         { 0x02, "Even" },
 452         { 0x03, "None" },
 453         { 0x04, "Forced to 0" },
 454         { 0x05, "Forced to 1" },
 455         { 0,    NULL }
 456 };
 457
 458 static const value_string q931_l1_modem_type_vals[] = {
 459         { 0x11, "V.21" },
 460         { 0x12, "V.22" },
 461         { 0x13, "V.22 bis" },
 462         { 0x14, "V.23" },
 463         { 0x15, "V.26" },
 464         { 0x16, "V.26 bis" },
 465         { 0x17, "V.26 ter" },
 466         { 0x18, "V.27" },
 467         { 0x19, "V.27 bis" },
 468         { 0x1A, "V.27 ter" },
 469         { 0x1B, "V.29" },
 470         { 0x1C, "V.32" },
 471         { 0x1E, "V.34" },
 472         { 0,    NULL }
 473 };
 474
 475 #define Q931_UIL2_USER_SPEC     0x10
 476
 477 static const value_string q931_uil2_vals[] = {
 478         { 0x01,                 "Basic mode ISO 1745" },
 479         { 0x02,                 "Q.921/I.441" },        /* LAPD */
 480         { 0x06,                 "X.25, link layer" },   /* LAPB */
 481         { 0x07,                 "X.25 multilink" },     /* or 0x0F? */
 482         { 0x08,                 "T.71 Extended LAPB" },
 483         { 0x09,                 "HDLC ARM" },
 484         { 0x0A,                 "HDLC NRM" },
 485         { 0x0B,                 "HDLC ABM" },
 486         { 0x0C,                 "ISO 8802/2 LLC" },
 487         { 0x0D,                 "X.75 Single Link Procedure" },
 488         { 0x0E,                 "Q.922" },
 489         { 0x0F,                 "Core aspects of Q.922" },
 490         { Q931_UIL2_USER_SPEC,  "User-specified" },
 491         { 0x11,                 "ISO 7776 DTE-DTE operation" },
 492         { 0,                    NULL }
 493 };
 494
 495 static const value_string q931_mode_vals[] = {
 496         { 0x20, "Normal mode" },
 497         { 0x40, "Extended mode" },
 498         { 0,    NULL }
 499 };
 500
 501 #define Q931_UIL3_X25_PL        0x06
 502 #define Q931_UIL3_ISO_8208      0x07    /* X.25-based */
 503 #define Q931_UIL3_X223          0x08    /* X.25-based */
 504 #define Q931_UIL3_TR_9577       0x0B
 505 #define Q931_UIL3_USER_SPEC     0x10
 506
 507 static const value_string q931_uil3_vals[] = {
 508         { 0x02,                 "Q.931/I.451" },
 509         { Q931_UIL3_X25_PL,     "X.25, packet layer" },
 510         { Q931_UIL3_ISO_8208,   "ISO/IEC 8208" },
 511         { Q931_UIL3_X223,       "X.223/ISO 8878" },
 512         { 0x09,                 "ISO/IEC 8473" },
 513         { 0x0A,                 "T.70" },
 514         { Q931_UIL3_TR_9577,    "ISO/IEC TR 9577" },
 515         { Q931_UIL3_USER_SPEC,  "User-specified" },
 516         { 0,                    NULL }
 517 };
 518
 519 /*
 520  * XXX - should this (or, rather, a routine to return a string containing
 521  * the stuff we put after "Protocol discriminator:") be in "packet-osi.c"?
 522  *
 523  * I.e., is the convention that 16-63 and 80-254 are for network-layer
 524  * or layer-3 protocols, and 64-79 are for national use, specific to
 525  * Q.931 (and maybe Q.2931), or is it a more general ISO standard?
 526  */
 527 static void
 528 dissect_q931_protocol_discriminator(tvbuff_t *tvb, int offset, proto_tree *tree)
 529 {
 530         unsigned int discriminator = tvb_get_guint8(tvb, offset);
 531         char *nlpid_string;
 532
 533         nlpid_string = match_strval(discriminator, nlpid_vals);
 534         if (nlpid_string != NULL) {
 535                 proto_tree_add_uint_format(tree, hf_q931_discriminator,
 536                          tvb, offset, 1, discriminator,
 537                          "Protocol discriminator: %s", nlpid_string);
 538         } else {
 539                 if ((discriminator >= 16 && discriminator < 63)
 540                     || ((discriminator >= 80) && (discriminator < 254))) {
 541                         proto_tree_add_uint_format(tree, hf_q931_discriminator,
 542                             tvb, offset, 1, discriminator,
 543                             "Protocol discriminator: Network layer or layer 3 protocol (0x%02X)",
 544                             discriminator);
 545                 } else if (discriminator >= 64 && discriminator <= 79) {
 546                         proto_tree_add_uint_format(tree, hf_q931_discriminator,
 547                             tvb, offset, 1, discriminator,
 548                             "Protocol discriminator: National use (0x%02X)",
 549                             discriminator);
 550                 } else {
 551                         proto_tree_add_uint_format(tree, hf_q931_discriminator,
 552                             tvb, offset, 1, discriminator,
 553                             "Protocol discriminator: Reserved (0x%02X)",
 554                             discriminator);
 555                 }
 556         }
 557 }
 558
 559 void
 560 dissect_q931_bearer_capability_ie(tvbuff_t *tvb, int offset, int len,
 561     proto_tree *tree)
 562 {
 563         guint8 octet;
 564         guint8 coding_standard;
 565         guint8 it_rate;
 566         guint8 modem_type;
 567         guint8 uil2_protocol;
 568         guint8 uil3_protocol;
 569         guint8 add_l3_info;
 570
 571         if (len == 0)
 572                 return;
 573         octet = tvb_get_guint8(tvb, offset);
 574         coding_standard = octet & 0x60;
 575         proto_tree_add_text(tree, tvb, offset, 1,
 576             "Coding standard: %s",
 577             val_to_str(coding_standard, q931_bc_coding_standard_vals, NULL));
 578         if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
 579                 /*
 580                  * We don't know how the bearer capability is encoded,
 581                  * so just dump it as data and be done with it.
 582                  */
 583                 proto_tree_add_text(tree, tvb, offset,
 584                     len, "Data: %s",
 585                     tvb_bytes_to_str(tvb, offset, len));
 586                 return;
 587         }
 588         proto_tree_add_text(tree, tvb, offset, 1,
 589             "Information transfer capability: %s",
 590             val_to_str(octet & 0x1F, q931_information_transfer_capability_vals,
 591               "Unknown (0x%02X)"));
 592         offset += 1;
 593         len -= 1;
 594
 595         /*
 596          * XXX - only in Low-layer compatibility information element.
 597          */
 598         if (!(octet & Q931_IE_VL_EXTENSION)) {
 599                 if (len == 0)
 600                         return;
 601                 octet = tvb_get_guint8(tvb, offset);
 602                 proto_tree_add_text(tree, tvb, offset, 1,
 603                     "Out-band negotiation %spossible",
 604                     (octet & 0x40) ? "" : "not ");
 605                 offset += 1;
 606                 len -= 1;
 607         }
 608
 609         if (len == 0)
 610                 return;
 611         octet = tvb_get_guint8(tvb, offset);
 612         proto_tree_add_text(tree, tvb, offset, 1,
 613             "Transfer mode: %s",
 614             val_to_str(octet & 0x60, q931_transfer_mode_vals,
 615               "Unknown (0x%02X)"));
 616         it_rate = octet & 0x1F;
 617         proto_tree_add_text(tree, tvb, offset, 1,
 618             "Information transfer rate: %s",
 619             val_to_str(it_rate, q931_information_transfer_rate_vals,
 620               "Unknown (0x%02X)"));
 621         offset += 1;
 622         len -= 1;
 623
 624         if (it_rate == Q931_IT_RATE_MULTIRATE) {
 625                 if (len == 0)
 626                         return;
 627                 proto_tree_add_text(tree, tvb, offset, 1, "Rate multiplier: %u", tvb_get_guint8(tvb, offset));
 628                 offset += 1;
 629                 len -= 1;
 630         }
 631
 632         if (len == 0)
 633                 return;
 634         octet = tvb_get_guint8(tvb, offset);
 635         if ((octet & 0x60) == 0x20) {
 636                 /*
 637                  * Layer 1 information.
 638                  */
 639                 proto_tree_add_text(tree, tvb, offset, 1,
 640                     "User information layer 1 protocol: %s",
 641                     val_to_str(octet & 0x1F, q931_uil1_vals,
 642                       "Unknown (0x%02X)"));
 643                 offset += 1;
 644                 len -= 1;
 645
 646                 if (octet & Q931_IE_VL_EXTENSION)
 647                         goto l1_done;
 648                 if (len == 0)
 649                         return;
 650                 octet = tvb_get_guint8(tvb, offset);
 651                 proto_tree_add_text(tree, tvb, offset, 1,
 652                     "Layer 1 is %s",
 653                     (octet & 0x40) ? "Asynchronous" : "Synchronous");
 654                 proto_tree_add_text(tree, tvb, offset, 1,
 655                     "Layer 1 in-band negotiation is %spossible",
 656                     (octet & 0x20) ? "" : "not ");
 657                 proto_tree_add_text(tree, tvb, offset, 1,
 658                     "User rate: %s",
 659                     val_to_str(octet & 0x1F, q931_l1_user_rate_vals,
 660                       "Unknown (0x%02X)"));
 661                 offset += 1;
 662                 len -= 1;
 663
 664                 if (octet & Q931_IE_VL_EXTENSION)
 665                         goto l1_done;
 666                 if (len == 0)
 667                         return;
 668                 octet = tvb_get_guint8(tvb, offset);
 669                 proto_tree_add_text(tree, tvb, offset, 1,
 670                     "Intermediate rate: %s",
 671                       val_to_str(octet & 0x60, q931_l1_intermediate_rate_vals,
 672                        "Unknown (0x%X)"));
 673                 proto_tree_add_text(tree, tvb, offset, 1,
 674                     "%s to send data with network independent clock",
 675                     (octet & 0x10) ? "Required" : "Not required");
 676                 proto_tree_add_text(tree, tvb, offset, 1,
 677                     "%s accept data with network independent clock",
 678                     (octet & 0x08) ? "Can" : "Cannot");
 679                 proto_tree_add_text(tree, tvb, offset, 1,
 680                     "%s to send data with flow control mechanism",
 681                     (octet & 0x04) ? "Required" : "Not required");
 682                 proto_tree_add_text(tree, tvb, offset, 1,
 683                     "%s accept data with flow control mechanism",
 684                     (octet & 0x02) ? "Can" : "Cannot");
 685                 offset += 1;
 686                 len -= 1;
 687
 688                 if (octet & Q931_IE_VL_EXTENSION)
 689                         goto l1_done;
 690                 if (len == 0)
 691                         return;
 692                 octet = tvb_get_guint8(tvb, offset);
 693                 proto_tree_add_text(tree, tvb, offset, 1,
 694                     "Rate adaption header %sincluded",
 695                     (octet & 0x40) ? "" : "not ");
 696                 proto_tree_add_text(tree, tvb, offset, 1,
 697                     "Multiple frame establishment %ssupported",
 698                     (octet & 0x20) ? "" : "not ");
 699                 proto_tree_add_text(tree, tvb, offset, 1,
 700                     "%s mode of operation",
 701                     (octet & 0x10) ? "Protocol sensitive" : "Bit transparent");
 702                 proto_tree_add_text(tree, tvb, offset, 1,
 703                     (octet & 0x08) ?
 704                       "Full protocol negotiation" : "LLI = 256 only");
 705                 proto_tree_add_text(tree, tvb, offset, 1,
 706                     "Message originator is %s",
 707                     (octet & 0x04) ? "Assignor only" : "Default assignee");
 708                 proto_tree_add_text(tree, tvb, offset, 1,
 709                     "Negotiation is done %s",
 710                     (octet & 0x02) ? "in-band" : "out-of-band");
 711                 offset += 1;
 712                 len -= 1;
 713
 714                 if (octet & Q931_IE_VL_EXTENSION)
 715                         goto l1_done;
 716                 if (len == 0)
 717                         return;
 718                 octet = tvb_get_guint8(tvb, offset);
 719                 proto_tree_add_text(tree, tvb, offset, 1,
 720                     "Stop bits: %s",
 721                       val_to_str(octet & 0x60, q931_l1_stop_bits_vals,
 722                        "Unknown (0x%X)"));
 723                 proto_tree_add_text(tree, tvb, offset, 1,
 724                     "Data bits: %s",
 725                       val_to_str(octet & 0x18, q931_l1_data_bits_vals,
 726                        "Unknown (0x%X)"));
 727                 proto_tree_add_text(tree, tvb, offset, 1,
 728                     "Parity: %s",
 729                       val_to_str(octet & 0x08, q931_l1_parity_vals,
 730                        "Unknown (0x%X)"));
 731
 732                 if (octet & Q931_IE_VL_EXTENSION)
 733                         goto l1_done;
 734                 if (len == 0)
 735                         return;
 736                 octet = tvb_get_guint8(tvb, offset);
 737                 proto_tree_add_text(tree, tvb, offset, 1,
 738                     "%s duplex",
 739                     (octet & 0x40) ? "Full" : "Half");
 740                 modem_type = octet & 0x3F;
 741                 if (modem_type <= 0x5 ||
 742                     (modem_type >= 0x20 && modem_type <= 0x2F)) {
 743                         proto_tree_add_text(tree, tvb, offset, 1,
 744                             "Modem type: National use 0x%02X", modem_type);
 745                 } else if (modem_type >= 0x30) {
 746                         proto_tree_add_text(tree, tvb, offset, 1,
 747                             "Modem type: User specified 0x%02X", modem_type);
 748                 } else {
 749                         proto_tree_add_text(tree, tvb, offset, 1,
 750                             "Modem type: %s",
 751                               val_to_str(modem_type, q931_l1_modem_type_vals,
 752                               "Unknown (0x%02X)"));
 753                 }
 754                 offset += 1;
 755                 len -= 1;
 756         }
 757 l1_done:
 758         ;
 759
 760         if (len == 0)
 761                 return;
 762         octet = tvb_get_guint8(tvb, offset);
 763         if ((octet & 0x60) == 0x40) {
 764                 /*
 765                  * Layer 2 information.
 766                  */
 767                 uil2_protocol = octet & 0x1F;
 768                 proto_tree_add_text(tree, tvb, offset, 1,
 769                     "User information layer 2 protocol: %s",
 770                     val_to_str(uil2_protocol, q931_uil2_vals,
 771                       "Unknown (0x%02X)"));
 772                 offset += 1;
 773                 len -= 1;
 774
 775                 /*
 776                  * XXX - only in Low-layer compatibility information element.
 777                  */
 778                 if (octet & Q931_IE_VL_EXTENSION)
 779                         goto l2_done;
 780                 if (len == 0)
 781                         return;
 782                 octet = tvb_get_guint8(tvb, offset);
 783                 if (uil2_protocol == Q931_UIL2_USER_SPEC) {
 784                         proto_tree_add_text(tree, tvb, offset, 1,
 785                             "User-specified layer 2 protocol information: 0x%02X",
 786                             octet & 0x7F);
 787                 } else {
 788                         proto_tree_add_text(tree, tvb, offset, 1,
 789                             "Mode: %s",
 790                             val_to_str(octet & 0x60, q931_mode_vals,
 791                               "Unknown (0x%02X)"));
 792                 }
 793                 offset += 1;
 794                 len -= 1;
 795
 796                 if (octet & Q931_IE_VL_EXTENSION)
 797                         goto l2_done;
 798                 if (len == 0)
 799                         return;
 800                 octet = tvb_get_guint8(tvb, offset);
 801                 proto_tree_add_text(tree, tvb, offset, 1,
 802                     "Window size: %u k", octet & 0x7F);
 803                 offset += 1;
 804                 len -= 1;
 805         }
 806 l2_done:
 807         ;
 808
 809         if (len == 0)
 810                 return;
 811         octet = tvb_get_guint8(tvb, offset);
 812         if ((octet & 0x60) == 0x60) {
 813                 /*
 814                  * Layer 3 information.
 815                  */
 816                 uil3_protocol = octet & 0x1F;
 817                 proto_tree_add_text(tree, tvb, offset, 1,
 818                     "User information layer 3 protocol: %s",
 819                     val_to_str(uil3_protocol, q931_uil3_vals,
 820                       "Unknown (0x%02X)"));
 821                 offset += 1;
 822                 len -= 1;
 823
 824
 825                 /*
 826                  * XXX - only in Low-layer compatibility information element.
 827                  */
 828                 if (octet & Q931_IE_VL_EXTENSION)
 829                         goto l3_done;
 830                 if (len == 0)
 831                         return;
 832                 octet = tvb_get_guint8(tvb, offset);
 833                 switch (uil3_protocol) {
 834
 835                 case Q931_UIL3_X25_PL:
 836                 case Q931_UIL3_ISO_8208:
 837                 case Q931_UIL3_X223:
 838                         proto_tree_add_text(tree, tvb, offset, 1,
 839                             "Mode: %s",
 840                             val_to_str(octet & 0x60, q931_mode_vals,
 841                               "Unknown (0x%02X)"));
 842                         offset += 1;
 843                         len -= 1;
 844
 845                         if (octet & Q931_IE_VL_EXTENSION)
 846                                 goto l3_done;
 847                         if (len == 0)
 848                                 return;
 849                         octet = tvb_get_guint8(tvb, offset);
 850                         proto_tree_add_text(tree, tvb, offset, 1,
 851                             "Default packet size: %u", octet & 0x0F);
 852                         offset += 1;
 853                         len -= 1;
 854
 855                         if (octet & Q931_IE_VL_EXTENSION)
 856                                 goto l3_done;
 857                         if (len == 0)
 858                                 return;
 859                         octet = tvb_get_guint8(tvb, offset);
 860                         proto_tree_add_text(tree, tvb, offset, 1,
 861                             "Packet window size: %u", octet & 0x7F);
 862                         offset += 1;
 863                         len -= 1;
 864                         break;
 865
 866                 case Q931_UIL3_USER_SPEC:
 867                         proto_tree_add_text(tree, tvb, offset, 1,
 868                             "Default packet size: %u octets",
 869                             1 << (octet & 0x0F));
 870                         offset += 1;
 871                         len -= 1;
 872                         break;
 873
 874                 case Q931_UIL3_TR_9577:
 875                         add_l3_info = (octet & 0x0F) << 4;
 876                         if (octet & Q931_IE_VL_EXTENSION)
 877                                 goto l3_done;
 878                         if (len == 0)
 879                                 return;
 880                         octet = tvb_get_guint8(tvb, offset + 1);
 881                         add_l3_info |= (octet & 0x0F);
 882                         proto_tree_add_text(tree, tvb, offset, 2,
 883                             "Additional layer 3 protocol information: %s",
 884                             val_to_str(add_l3_info, nlpid_vals,
 885                               "Unknown (0x%02X)"));
 886                         offset += 2;
 887                         len -= 2;
 888                         break;
 889                 }
 890         }
 891 l3_done:
 892         ;
 893 }
 894
 895 /*
 896  * Dissect a Cause information element.
 897  */
 898 static const value_string q931_cause_coding_standard_vals[] = {
 899         { 0x00, "ITU-T standardized coding" },
 900         { 0x20, "ISO/IEC standard" },
 901         { 0x40, "National standard" },
 902         { 0x60, "Standard specific to identified location" },
 903         { 0,    NULL }
 904 };
 905
 906 static const value_string q931_cause_location_vals[] = {
 907         { 0x00, "User (U)" },
 908         { 0x01, "Private network serving the local user (LPN)" },
 909         { 0x02, "Public network serving the local user (LN)" },
 910         { 0x03, "Transit network (TN)" },
 911         { 0x04, "Public network serving the remote user (RLN)" },
 912         { 0x05, "Private network serving the remote user (RPN)" },
 913         { 0x07, "International network (INTL)" },
 914         { 0x0A, "Network beyond interworking point (BI)" },
 915         { 0,    NULL }
 916 };
 917
 918 static const value_string q931_cause_recommendation_vals[] = {
 919         { 0x00, "Q.931" },
 920         { 0x03, "X.21" },
 921         { 0x04, "X.25" },
 922         { 0x05, "Q.1031/Q.1051" },
 923         { 0,    NULL }
 924 };
 925
 926 /*
 927  * Cause codes for Cause.
 928  */
 929 static const value_string q931_cause_code_vals[] = {
 930         { 0x00, "Valid cause code not yet received" },
 931         { 0x01, "Unallocated (unassigned) number" },
 932         { 0x02, "No route to specified transit network" },
 933         { 0x03, "No route to destination" },
 934         { 0x04, "Send special information tone" },
 935         { 0x05, "Misdialled trunk prefix" },
 936         { 0x06, "Channel unacceptable" },
 937         { 0x07, "Call awarded and being delivered in an established channel" },
 938         { 0x08, "Prefix 0 dialed but not allowed" },
 939         { 0x09, "Prefix 1 dialed but not allowed" },
 940         { 0x0A, "Prefix 1 dialed but not required" },
 941         { 0x0B, "More digits received than allowed, call is proceeding" },
 942         { 0x10, "Normal call clearing" },
 943         { 0x11, "User busy" },
 944         { 0x12, "No user responding" },
 945         { 0x13, "No answer from user (user alerted)" },
 946         { 0x14, "Subscriber absent" },
 947         { 0x15, "Call rejected" },
 948         { 0x16, "Number changed" },
 949         { 0x17, "Reverse charging rejected" },
 950         { 0x18, "Call suspended" },
 951         { 0x19, "Call resumed" },
 952         { 0x1A, "Non-selected user clearing" },
 953         { 0x1B, "Destination out of order" },
 954         { 0x1C, "Invalid number format (incomplete number)" },
 955         { 0x1D, "Facility rejected" },
 956         { 0x1E, "Response to STATUS ENQUIRY" },
 957         { 0x1F, "Normal unspecified" },
 958         { 0x21, "Circuit out of order" },
 959         { 0x22, "No circuit/channel available" },
 960         { 0x23, "Destination unattainable" },
 961         { 0x25, "Degraded service" },
 962         { 0x26, "Network out of order" },
 963         { 0x27, "Transit delay range cannot be achieved" },
 964         { 0x28, "Throughput range cannot be achieved" },
 965         { 0x29, "Temporary failure" },
 966         { 0x2A, "Switching equipment congestion" },
 967         { 0x2B, "Access information discarded" },
 968         { 0x2C, "Requested circuit/channel not available" },
 969         { 0x2D, "Pre-empted" },
 970         { 0x2E, "Precedence call blocked" },
 971         { 0x2F, "Resources unavailable, unspecified" },
 972         { 0x31, "Quality of service unavailable" },
 973         { 0x32, "Requested facility not subscribed" },
 974         { 0x33, "Reverse charging not allowed" },
 975         { 0x34, "Outgoing calls barred" },
 976         { 0x35, "Outgoing calls barred within CUG" },
 977         { 0x36, "Incoming calls barred" },
 978         { 0x37, "Incoming calls barred within CUG" },
 979         { 0x38, "Call waiting not subscribed" },
 980         { 0x39, "Bearer capability not authorized" },
 981         { 0x3A, "Bearer capability not presently available" },
 982         { 0x3E, "Inconsistency in designated outgoing access information and subscriber class" },
 983         { 0x3F, "Service or option not available, unspecified" },
 984         { 0x41, "Bearer capability not implemented" },
 985         { 0x42, "Channel type not implemented" },
 986         { 0x43, "Transit network selection not implemented" },
 987         { 0x44, "Message not implemented" },
 988         { 0x45, "Requested facility not implemented" },
 989         { 0x46, "Only restricted digital information bearer capability is available" },
 990         { 0x4F, "Service or option not implemented, unspecified" },
 991         { 0x51, "Invalid call reference value" },
 992         { 0x52, "Identified channel does not exist" },
 993         { 0x53, "Call identity does not exist for suspended call" },
 994         { 0x54, "Call identity in use" },
 995         { 0x55, "No call suspended" },
 996         { 0x56, "Call having the requested call identity has been cleared" },
 997         { 0x57, "Called user not member of CUG" },
 998         { 0x58, "Incompatible destination" },
 999         { 0x59, "Non-existent abbreviated address entry" },
1000         { 0x5A, "Destination address missing, and direct call not subscribed" },
1001         { 0x5B, "Invalid transit network selection (national use)" },
1002         { 0x5C, "Invalid facility parameter" },
1003         { 0x5D, "Mandatory information element is missing" },
1004         { 0x5F, "Invalid message, unspecified" },
1005         { 0x60, "Mandatory information element is missing" },
1006         { 0x61, "Message type non-existent or not implemented" },
1007         { 0x62, "Message not compatible with call state or message type non-existent or not implemented" },
1008         { 0x63, "Information element nonexistant or not implemented" },
1009         { 0x64, "Invalid information element contents" },
1010         { 0x65, "Message not compatible with call state" },
1011         { 0x66, "Recovery on timer expiry" },
1012         { 0x67, "Parameter non-existent or not implemented - passed on" },
1013         { 0x6E, "Message with unrecognized parameter discarded" },
1014         { 0x6F, "Protocol error, unspecified" },
1015         { 0x7F, "Internetworking, unspecified" },
1016         { 0,    NULL }
1017 };
1018
1019 static void
1020 dissect_q931_cause_ie(tvbuff_t *tvb, int offset, int len,
1021     proto_tree *tree)
1022 {
1023         guint8 octet;
1024         guint8 coding_standard;
1025
1026         if (len == 0)
1027                 return;
1028         octet = tvb_get_guint8(tvb, offset);
1029         coding_standard = octet & 0x60;
1030         proto_tree_add_text(tree, tvb, offset, 1,
1031             "Coding standard: %s",
1032             val_to_str(coding_standard, q931_cause_coding_standard_vals, NULL));
1033         if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
1034                 /*
1035                  * We don't know how the cause is encoded,
1036                  * so just dump it as data and be done with it.
1037                  */
1038                 proto_tree_add_text(tree, tvb, offset,
1039                     len, "Data: %s",
1040                     tvb_bytes_to_str(tvb, offset, len));
1041                 return;
1042         }
1043         proto_tree_add_text(tree, tvb, offset, 1,
1044             "Location: %s",
1045             val_to_str(octet & 0x0F, q931_cause_location_vals,
1046               "Unknown (0x%X)"));
1047         offset += 1;
1048         len -= 1;
1049
1050         if (!(octet & Q931_IE_VL_EXTENSION)) {
1051                 if (len == 0)
1052                         return;
1053                 octet = tvb_get_guint8(tvb, offset);
1054                 proto_tree_add_text(tree, tvb, offset, 1,
1055                     "Recommendation: %s",
1056                     val_to_str(octet & 0x7F, q931_cause_recommendation_vals,
1057                       "Unknown (0x%02X)"));
1058                 offset += 1;
1059                 len -= 1;
1060         }
1061
1062         if (len == 0)
1063                 return;
1064         octet = tvb_get_guint8(tvb, offset);
1065         proto_tree_add_text(tree, tvb, offset, 1,
1066             "Cause value: %s",
1067             val_to_str(octet & 0x7F, q931_cause_code_vals,
1068               "Unknown (0x%02X)"));
1069         offset += 1;
1070         len -= 1;
1071
1072         if (len == 0)
1073                 return;
1074         proto_tree_add_text(tree, tvb, offset, len,
1075             "Diagnostics: %s",
1076             tvb_bytes_to_str(tvb, offset, len));
1077 }
1078
1079 /*
1080  * Dissect a Call state information element.
1081  */
1082 static const value_string q931_coding_standard_vals[] = {
1083         { 0x00, "ITU-T standardized coding" },
1084         { 0x20, "ISO/IEC standard" },
1085         { 0x40, "National standard" },
1086         { 0x60, "Standard defined for the network" },
1087         { 0,    NULL }
1088 };
1089
1090 static const value_string q931_call_state_vals[] = {
1091         { 0x00, "Null" },
1092         { 0x01, "Call initiated" },
1093         { 0x02, "Overlap sending" },
1094         { 0x03, "Outgoing call proceeding" },
1095         { 0x04, "Call delivered" },
1096         { 0x06, "Call present" },
1097         { 0x07, "Call received" },
1098         { 0x09, "Connect request" },
1099         { 0x0A, "Incoming call proceeding" },
1100         { 0x0B, "Active" },
1101         { 0x0C, "Disconnect request" },
1102         { 0x0F, "Disconnect indication" },
1103         { 0x11, "Suspend request" },
1104         { 0x13, "Resume request" },
1105         { 0x16, "Release request" },
1106         { 0x19, "Overlap receiving" },
1107         { 0x3D, "Restart request" },
1108         { 0x3E, "Restart" },
1109         { 0,    NULL }
1110 };
1111
1112 static void
1113 dissect_q931_call_state_ie(tvbuff_t *tvb, int offset, int len,
1114     proto_tree *tree)
1115 {
1116         guint8 octet;
1117         guint8 coding_standard;
1118
1119         if (len == 0)
1120                 return;
1121         octet = tvb_get_guint8(tvb, offset);
1122         coding_standard = octet & 0x60;
1123         proto_tree_add_text(tree, tvb, offset, 1,
1124             "Coding standard: %s",
1125             val_to_str(coding_standard, q931_coding_standard_vals, NULL));
1126         if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
1127                 /*
1128                  * We don't know how the call state is encoded,
1129                  * so just dump it as data and be done with it.
1130                  */
1131                 proto_tree_add_text(tree, tvb, offset,
1132                     len, "Data: %s",
1133                     tvb_bytes_to_str(tvb, offset, len));
1134                 return;
1135         }
1136         proto_tree_add_text(tree, tvb, offset, 1,
1137             "Call state: %s",
1138             val_to_str(octet & 0x3F, q931_call_state_vals,
1139               "Unknown (0x%02X)"));
1140 }
1141
1142 /*
1143  * Dissect a Channel identification information element.
1144  */
1145 #define Q931_INTERFACE_IDENTIFIED       0x40
1146 #define Q931_NOT_BASIC_CHANNEL          0x20
1147
1148 static const value_string q931_basic_channel_selection_vals[] = {
1149         { 0x00, "No channel" },
1150         { 0x01, "B1 channel" },
1151         { 0x02, "B2 channel" },
1152         { 0x03, "Any channel" },
1153         { 0,    NULL }
1154 };
1155
1156 static const value_string q931_not_basic_channel_selection_vals[] = {
1157         { 0x00, "No channel" },
1158         { 0x01, "Channel indicated in following octets" },
1159         { 0x03, "Any channel" },
1160         { 0,    NULL }
1161 };
1162
1163 #define Q931_IS_SLOT_MAP                0x10
1164
1165 static const value_string q931_element_type_vals[] = {
1166         { 0x03, "B-channel units" },
1167         { 0x06, "H0-channel units" },
1168         { 0x08, "H11-channel units" },
1169         { 0x09, "H12-channel units" },
1170         { 0,    NULL }
1171 };
1172
1173 static void
1174 dissect_q931_channel_identification_ie(tvbuff_t *tvb, int offset, int len,
1175     proto_tree *tree)
1176 {
1177         guint8 octet;
1178         int identifier_offset;
1179         int identifier_len;
1180         guint8 coding_standard;
1181
1182         if (len == 0)
1183                 return;
1184         octet = tvb_get_guint8(tvb, offset);
1185         proto_tree_add_text(tree, tvb, offset, 1,
1186             "Interface %s identified",
1187             (octet & Q931_INTERFACE_IDENTIFIED) ? "explicitly" : "implicitly");
1188         proto_tree_add_text(tree, tvb, offset, 1,
1189             "%s interface",
1190             (octet & Q931_NOT_BASIC_CHANNEL) ? "Not basic" : "Basic");
1191         proto_tree_add_text(tree, tvb, offset, 1,
1192             "Indicated channel is %s",
1193             (octet & 0x08) ? "required" : "preferred");
1194         proto_tree_add_text(tree, tvb, offset, 1,
1195             "Indicated channel is %sthe D-channel",
1196             (octet & 0x04) ? "" : "not ");
1197         if (octet & Q931_NOT_BASIC_CHANNEL) {
1198                 proto_tree_add_text(tree, tvb, offset, 1,
1199                     "Channel selection: %s",
1200                     val_to_str(octet & 0x03, q931_not_basic_channel_selection_vals,
1201                       "Unknown (0x%X)"));
1202         } else {
1203                 proto_tree_add_text(tree, tvb, offset, 1,
1204                     "Channel selection: %s",
1205                     val_to_str(octet & 0x03, q931_basic_channel_selection_vals,
1206                       NULL));
1207         }
1208         offset += 1;
1209         len -= 1;
1210
1211         if (octet & Q931_INTERFACE_IDENTIFIED) {
1212                 identifier_offset = offset;
1213                 identifier_len = 0;
1214                 do {
1215                         if (len == 0)
1216                                 break;
1217                         octet = tvb_get_guint8(tvb, offset);
1218                         offset += 1;
1219                         len -= 1;
1220                         identifier_len++;
1221                 } while (!(octet & Q931_IE_VL_EXTENSION));
1222
1223                 /*
1224                  * XXX - do we want to strip off the 8th bit on the
1225                  * last octet of the interface identifier?
1226                  */
1227                 if (identifier_len != 0) {
1228                         proto_tree_add_text(tree, tvb, identifier_offset,
1229                             identifier_len, "Interface identifier: %s",
1230                             bytes_to_str(
1231                               tvb_get_ptr(tvb, identifier_offset, identifier_len),
1232                               identifier_len));
1233                 }
1234         }
1235
1236         if (octet & Q931_NOT_BASIC_CHANNEL) {
1237                 if (len == 0)
1238                         return;
1239                 octet = tvb_get_guint8(tvb, offset);
1240                 coding_standard = octet & 0x60;
1241                 proto_tree_add_text(tree, tvb, offset, 1,
1242                     "Coding standard: %s",
1243                     val_to_str(coding_standard, q931_coding_standard_vals,
1244                       NULL));
1245                 if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
1246                         /*
1247                          * We don't know how the channel identifier is
1248                          * encoded, so just dump it as data and be done
1249                          * with it.
1250                          */
1251                         proto_tree_add_text(tree, tvb, offset,
1252                             len, "Data: %s",
1253                             tvb_bytes_to_str(tvb, offset, len));
1254                         return;
1255                 }
1256                 proto_tree_add_text(tree, tvb, offset, 1,
1257                     "Channel is indicated by %s",
1258                     (octet & Q931_IS_SLOT_MAP) ? "slot map" : "number");
1259                 proto_tree_add_text(tree, tvb, offset, 1,
1260                     "%s type: %s",
1261                     (octet & Q931_IS_SLOT_MAP) ? "Map element" : "Channel",
1262                     val_to_str(octet & 0x0F, q931_element_type_vals,
1263                         "Unknown (0x%02X)"));
1264
1265                 /*
1266                  * XXX - dump the channel number or slot map.
1267                  */
1268         }
1269 }
1270
1271 /*
1272  * Dissect a Progress indicator information element.
1273  */
1274 static const value_string q931_progress_description_vals[] = {
1275         { 0x01, "Call is not end-to-end ISDN - progress information available in-band" },
1276         { 0x02, "Destination address is non-ISDN" },
1277         { 0x03, "Origination address is non-ISDN" },
1278         { 0x04, "Call has returned to the ISDN" },
1279         { 0x05, "Interworking has occurred and has resulted in a telecommunications service change" },
1280         { 0x08, "In-band information or an appropriate pattern is now available" },
1281         { 0,    NULL }
1282 };
1283
1284 void
1285 dissect_q931_progress_indicator_ie(tvbuff_t *tvb, int offset, int len,
1286     proto_tree *tree)
1287 {
1288         guint8 octet;
1289         guint8 coding_standard;
1290
1291         if (len == 0)
1292                 return;
1293         octet = tvb_get_guint8(tvb, offset);
1294         coding_standard = octet & 0x60;
1295         proto_tree_add_text(tree, tvb, offset, 1,
1296             "Coding standard: %s",
1297             val_to_str(coding_standard, q931_cause_coding_standard_vals, NULL));
1298         if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
1299                 /*
1300                  * We don't know how the progress indicator is encoded,
1301                  * so just dump it as data and be done with it.
1302                  */
1303                 proto_tree_add_text(tree, tvb, offset,
1304                     len, "Data: %s",
1305                     tvb_bytes_to_str(tvb, offset, len));
1306                 return;
1307         }
1308         proto_tree_add_text(tree, tvb, offset, 1,
1309             "Location: %s",
1310             val_to_str(octet & 0x0F, q931_cause_location_vals,
1311               "Unknown (0x%X)"));
1312         offset += 1;
1313         len -= 1;
1314
1315         if (len == 0)
1316                 return;
1317         octet = tvb_get_guint8(tvb, offset);
1318         proto_tree_add_text(tree, tvb, offset, 1,
1319             "Progress description: %s",
1320             val_to_str(octet & 0x7F, q931_progress_description_vals,
1321               "Unknown (0x%02X)"));
1322 }
1323
1324 /*
1325  * Dissect a Network-specific facilities or Transit network selection
1326  * information element.
1327  */
1328 static const value_string q931_netid_type_vals[] = {
1329         { 0x00, "User specified" },
1330         { 0x20, "National network identification" },
1331         { 0x30, "International network identification" },
1332         { 0,    NULL }
1333 };
1334
1335 static const value_string q931_netid_plan_vals[] = {
1336         { 0x00, "Unknown" },
1337         { 0x01, "Carrier Identification Code" },
1338         { 0x03, "X.121 data network identification code" },
1339         { 0,    NULL }
1340 };
1341
1342 static void
1343 dissect_q931_ns_facilities_ie(tvbuff_t *tvb, int offset, int len,
1344     proto_tree *tree)
1345 {
1346         guint8 octet;
1347         int netid_len;
1348
1349         if (len == 0)
1350                 return;
1351         octet = tvb_get_guint8(tvb, offset);
1352         netid_len = octet & 0x7F;
1353         proto_tree_add_text(tree, tvb, offset, 1,
1354             "Network identification length: %u",
1355             netid_len);
1356         offset += 1;
1357         len -= 1;
1358         if (netid_len != 0) {
1359                 if (len == 0)
1360                         return;
1361                 octet = tvb_get_guint8(tvb, offset);
1362                 proto_tree_add_text(tree, tvb, offset, 1,
1363                     "Type of network identification: %s",
1364                     val_to_str(octet & 0x70, q931_netid_type_vals,
1365                       "Unknown (0x%02X)"));
1366                 proto_tree_add_text(tree, tvb, offset, 1,
1367                     "Network identification plan: %s",
1368                     val_to_str(octet & 0x0F, q931_netid_plan_vals,
1369                       "Unknown (0x%02X)"));
1370                 offset += 1;
1371                 len -= 1;
1372                 netid_len--;
1373
1374                 if (len == 0)
1375                         return;
1376                 if (netid_len > len)
1377                         netid_len = len;
1378                 if (netid_len != 0) {
1379                         proto_tree_add_text(tree, tvb, offset, netid_len,
1380                             "Network identification: %s",
1381                             tvb_format_text(tvb, offset, netid_len));
1382                         offset += netid_len;
1383                         len -= netid_len;
1384                 }
1385         }
1386
1387         /*
1388          * Whatever is left is the network-specific facility
1389          * specification.
1390          */
1391          if (len == 0)
1392                 return;
1393         proto_tree_add_text(tree, tvb, offset,
1394             len, "Network-specific facility specification: %s",
1395             tvb_bytes_to_str(tvb, offset, len));
1396 }
1397
1398 /*
1399  * Dissect a Notification indicator information element.
1400  */
1401 static const value_string q931_notification_description_vals[] = {
1402         { 0x00, "User suspended" },
1403         { 0x01, "User resumed" },
1404         { 0x02, "Bearer service change" },
1405         { 0,    NULL }
1406 };
1407
1408 static void
1409 dissect_q931_notification_indicator_ie(tvbuff_t *tvb, int offset, int len,
1410     proto_tree *tree)
1411 {
1412         guint8 octet;
1413
1414         if (len == 0)
1415                 return;
1416         octet = tvb_get_guint8(tvb, offset);
1417         proto_tree_add_text(tree, tvb, offset, 1,
1418             "Notification description: %s",
1419             val_to_str(octet & 0x7F, q931_notification_description_vals,
1420               "Unknown (0x%02X)"));
1421 }
1422
1423 /*
1424  * Dissect a Date/time information element.
1425  */
1426 static void
1427 dissect_q931_date_time_ie(tvbuff_t *tvb, int offset, int len,
1428     proto_tree *tree)
1429 {
1430         if (len != 6) {
1431                 proto_tree_add_text(tree, tvb, offset, len,
1432                     "Date/time: length is %d, should be 6\n", len);
1433                 return;
1434         }
1435         /*
1436          * XXX - what is "year" relative to?  Is "month" 0-origin or
1437          * 1-origin?  Q.931 doesn't say....
1438          */
1439         proto_tree_add_text(tree, tvb, offset, 6,
1440             "Date/time: %02u-%02u-%02u %02u:%02u:%02u",
1441             tvb_get_guint8(tvb, offset + 0), tvb_get_guint8(tvb, offset + 1), tvb_get_guint8(tvb, offset + 2),
1442             tvb_get_guint8(tvb, offset + 3), tvb_get_guint8(tvb, offset + 4), tvb_get_guint8(tvb, offset + 5));
1443 }
1444
1445 /*
1446  * Dissect a Signal information element.
1447  */
1448 static const value_string q931_signal_vals[] = {
1449         { 0x00, "Dial tone on" },
1450         { 0x01, "Ring tone on" },
1451         { 0x02, "Intercept tone on" },
1452         { 0x03, "Network congestion tone on" }, /* "fast busy" */
1453         { 0x04, "Busy tone on" },
1454         { 0x05, "Confirm tone on" },
1455         { 0x06, "Answer tone on" },
1456         { 0x07, "Call waiting tone on" },
1457         { 0x08, "Off-hoke warning tone on" },
1458         { 0x09, "Preemption tone on" },
1459         { 0x3F, "Tones off" },
1460         { 0x40, "Alerting on - pattern 0" },
1461         { 0x41, "Alerting on - pattern 1" },
1462         { 0x42, "Alerting on - pattern 2" },
1463         { 0x43, "Alerting on - pattern 3" },
1464         { 0x44, "Alerting on - pattern 4" },
1465         { 0x45, "Alerting on - pattern 5" },
1466         { 0x46, "Alerting on - pattern 6" },
1467         { 0x47, "Alerting on - pattern 7" },
1468         { 0x4F, "Alerting off" },
1469         { 0,    NULL }
1470 };
1471
1472 static void
1473 dissect_q931_signal_ie(tvbuff_t *tvb, int offset, int len,
1474     proto_tree *tree)
1475 {
1476         if (len != 1) {
1477                 proto_tree_add_text(tree, tvb, offset, len,
1478                     "Signal: length is %d, should be 1\n", len);
1479                 return;
1480         }
1481         proto_tree_add_text(tree, tvb, offset, 1,
1482             "Signal: %s",
1483             val_to_str(tvb_get_guint8(tvb, offset), q931_signal_vals,
1484                 "Unknown (0x%02X)"));
1485 }
1486
1487 /*
1488  * Dissect an Information rate information element.
1489  */
1490 static const value_string q931_throughput_class_vals[] = {
1491         { 0x03, "75 bit/s" },
1492         { 0x04, "150 bit/s" },
1493         { 0x05, "300 bit/s" },
1494         { 0x06, "600 bit/s" },
1495         { 0x07, "1200 bit/s" },
1496         { 0x08, "2400 bit/s" },
1497         { 0x09, "4800 bit/s" },
1498         { 0x0A, "9600 bit/s" },
1499         { 0x0B, "19200 bit/s" },
1500         { 0x0C, "48000 bit/s" },
1501         { 0x0D, "64000 bit/s" },
1502         { 0,    NULL }
1503 };
1504
1505 static void
1506 dissect_q931_information_rate_ie(tvbuff_t *tvb, int offset, int len,
1507     proto_tree *tree)
1508 {
1509         if (len != 4) {
1510                 proto_tree_add_text(tree, tvb, offset, len,
1511                     "Information rate: length is %d, should be 4\n", len);
1512                 return;
1513         }
1514         proto_tree_add_text(tree, tvb, offset + 0, 1,
1515             "Incoming information rate: %s",
1516             val_to_str(tvb_get_guint8(tvb, offset + 0) & 0x1F,
1517               q931_throughput_class_vals, "Unknown (0x%02X)"));
1518         proto_tree_add_text(tree, tvb, offset + 1, 1,
1519             "Outgoing information rate: %s",
1520             val_to_str(tvb_get_guint8(tvb, offset + 1) & 0x1F,
1521               q931_throughput_class_vals, "Unknown (0x%02X)"));
1522         proto_tree_add_text(tree, tvb, offset + 2, 1,
1523             "Minimum incoming information rate: %s",
1524             val_to_str(tvb_get_guint8(tvb, offset + 2) & 0x1F,
1525               q931_throughput_class_vals, "Unknown (0x%02X)"));
1526         proto_tree_add_text(tree, tvb, offset + 3, 1,
1527             "Minimum outgoing information rate: %s",
1528             val_to_str(tvb_get_guint8(tvb, offset + 3) & 0x1F,
1529               q931_throughput_class_vals, "Unknown (0x%02X)"));
1530 }
1531
1532 static int
1533 dissect_q931_guint16_value(tvbuff_t *tvb, int offset, int len,
1534     proto_tree *tree, char *label)
1535 {
1536         guint8 octet;
1537         guint16 value;
1538         int value_len;
1539
1540         value_len = 0;
1541
1542         octet = tvb_get_guint8(tvb, offset);
1543         if (octet & Q931_IE_VL_EXTENSION) {
1544                 /*
1545                  * Only one octet long - error.
1546                  */
1547                 goto bad_length;
1548         }
1549         value = (octet & 0x3) << 14;
1550         offset += 1;
1551         len -= 1;
1552         value_len++;
1553
1554         if (len == 0) {
1555                 /*
1556                  * We've reached the end of the information element - error.
1557                  */
1558                 goto past_end;
1559         }
1560         octet = tvb_get_guint8(tvb, offset);
1561         if (octet & Q931_IE_VL_EXTENSION) {
1562                 /*
1563                  * Only two octets long - error.
1564                  */
1565                 goto bad_length;
1566         }
1567         value |= (octet & 0x7F) << 7;
1568         offset += 1;
1569         len -= 1;
1570         value_len++;
1571
1572         if (len == 0) {
1573                 /*
1574                  * We've reached the end of the information element - error.
1575                  */
1576                 goto past_end;
1577         }
1578         octet = tvb_get_guint8(tvb, offset);
1579         if (!(octet & Q931_IE_VL_EXTENSION)) {
1580                 /*
1581                  * More than three octets long - error.
1582                  */
1583                 goto bad_length;
1584         }
1585         value |= (octet & 0x7F);
1586         offset += 1;
1587         len -= 1;
1588         value_len++;
1589
1590         proto_tree_add_text(tree, tvb, offset, value_len, "%s: %u ms", label,
1591             value);
1592         return value_len;
1593
1594 past_end:
1595         proto_tree_add_text(tree, tvb, offset, len,
1596             "%s goes past end of information element", label);
1597         return -1;
1598
1599 bad_length:
1600         proto_tree_add_text(tree, tvb, offset, len, "%s isn't 3 octets long",
1601             label);
1602         return -1;
1603 }
1604
1605 /*
1606  * Dissect an End-to-end transit delay information element.
1607  */
1608 static void
1609 dissect_q931_e2e_transit_delay_ie(tvbuff_t *tvb, int offset, int len,
1610     proto_tree *tree)
1611 {
1612         int value_len;
1613
1614         if (len == 0)
1615                 return;
1616         value_len = dissect_q931_guint16_value(tvb, offset, len, tree,
1617             "Cumulative transit delay");
1618         if (value_len < 0)
1619                 return; /* error */
1620         offset += value_len;
1621         len -= value_len;
1622
1623         if (len == 0)
1624                 return;
1625         value_len = dissect_q931_guint16_value(tvb, offset, len, tree,
1626             "Requested end-to-end transit delay");
1627         if (value_len < 0)
1628                 return; /* error */
1629         offset += value_len;
1630         len -= value_len;
1631
1632         if (len == 0)
1633                 return;
1634         value_len = dissect_q931_guint16_value(tvb, offset, len, tree,
1635             "Maximum end-to-end transit delay");
1636 }
1637
1638 /*
1639  * Dissect a Transit delay selection and indication information element.
1640  */
1641 static void
1642 dissect_q931_td_selection_and_int_ie(tvbuff_t *tvb, int offset, int len,
1643     proto_tree *tree)
1644 {
1645         if (len == 0)
1646                 return;
1647         dissect_q931_guint16_value(tvb, offset, len, tree,
1648             "Transit delay");
1649 }
1650
1651 /*
1652  * Dissect a Packet layer binary parameters information element.
1653  */
1654 static const value_string q931_fast_selected_vals[] = {
1655         { 0x00, "Fast select not requested" },
1656         { 0x08, "Fast select not requested" },
1657         { 0x10, "Fast select requested with no restriction of response" },
1658         { 0x18, "Fast select requested with restrictions of response" },
1659         { 0x00, NULL }
1660 };
1661
1662 static void
1663 dissect_q931_pl_binary_parameters_ie(tvbuff_t *tvb, int offset, int len,
1664     proto_tree *tree)
1665 {
1666         guint8 octet;
1667
1668         if (len == 0)
1669                 return;
1670         octet = tvb_get_guint8(tvb, offset);
1671         proto_tree_add_text(tree, tvb, offset, 1,
1672             "Fast select: %s",
1673             val_to_str(octet & 0x18, q931_fast_selected_vals, NULL));
1674         proto_tree_add_text(tree, tvb, offset, 1,
1675             "%s",
1676             (octet & 0x04) ? "No request/request denied" :
1677                              "Request indicated/request accepted");
1678         proto_tree_add_text(tree, tvb, offset, 1,
1679             "%s confirmation",
1680             (octet & 0x02) ? "Link-by-link" : "End-to-end");
1681         proto_tree_add_text(tree, tvb, offset, 1,
1682             "Modulus %u sequencing",
1683             (octet & 0x01) ? 8 : 128);
1684 }
1685
1686 /*
1687  * Dissect a Packet layer window size information element.
1688  */
1689 static void
1690 dissect_q931_pl_window_size_ie(tvbuff_t *tvb, int offset, int len,
1691     proto_tree *tree)
1692 {
1693         if (len == 0)
1694                 return;
1695         proto_tree_add_text(tree, tvb, offset, 1,
1696             "Forward value: %u", tvb_get_guint8(tvb, offset) & 0x7F);
1697         offset += 1;
1698         len -= 1;
1699
1700         if (len == 0)
1701                 return;
1702         proto_tree_add_text(tree, tvb, offset, 1,
1703             "Backward value: %u", tvb_get_guint8(tvb, offset) & 0x7F);
1704 }
1705
1706 /*
1707  * Dissect a Packet size information element.
1708  */
1709 static void
1710 dissect_q931_packet_size_ie(tvbuff_t *tvb, int offset, int len,
1711     proto_tree *tree)
1712 {
1713         if (len == 0)
1714                 return;
1715         proto_tree_add_text(tree, tvb, offset, 1,
1716             "Forward value: %u", tvb_get_guint8(tvb, offset) & 0x7F);
1717         offset += 1;
1718         len -= 1;
1719
1720         if (len == 0)
1721                 return;
1722         proto_tree_add_text(tree, tvb, offset, 1,
1723             "Backward value: %u", tvb_get_guint8(tvb, offset) & 0x7F);
1724 }
1725
1726 /*
1727  * Dissect a Closed user group information element.
1728  */
1729 static const value_string q931_cug_indication_vals[] = {
1730         { 0x01, "Closed user group selection" },
1731         { 0x02, "Closed user group with outgoing access selection and indication" },
1732         { 0,    NULL }
1733 };
1734
1735 static void
1736 dissect_q931_cug_ie(tvbuff_t *tvb, int offset, int len, proto_tree *tree)
1737 {
1738         if (len == 0)
1739                 return;
1740         proto_tree_add_text(tree, tvb, offset, 1,
1741             "CUG indication: %s",
1742             val_to_str(tvb_get_guint8(tvb, offset) & 0x07,
1743               q931_cug_indication_vals, "Unknown (0x%02X)"));
1744         offset += 1;
1745         len -= 1;
1746
1747         if (len == 0)
1748                 return;
1749         proto_tree_add_text(tree, tvb, offset, len, "CUG index code: %s",
1750             tvb_format_text(tvb, offset, len));
1751 }
1752
1753 /*
1754  * Dissect a Reverse charging indication information element.
1755  */
1756 static const value_string q931_reverse_charging_indication_vals[] = {
1757         { 0x01, "Reverse charging requested" },
1758         { 0,    NULL }
1759 };
1760
1761 static void
1762 dissect_q931_reverse_charge_ind_ie(tvbuff_t *tvb, int offset, int len,
1763     proto_tree *tree)
1764 {
1765         if (len == 0)
1766                 return;
1767         proto_tree_add_text(tree, tvb, offset, 1,
1768             "Reverse charging indication: %s",
1769             val_to_str(tvb_get_guint8(tvb, offset) & 0x07,
1770               q931_reverse_charging_indication_vals, "Unknown (0x%02X)"));
1771 }
1772
1773 /*
1774  * Dissect a (phone) number information element.
1775  */
1776 static const value_string q931_number_type_vals[] = {
1777         { 0x00, "Unknown" },
1778         { 0x10, "International number" },
1779         { 0x20, "National number" },
1780         { 0x30, "Network specific number" },
1781         { 0x40, "Subscriber number" },
1782         { 0x60, "Abbreviated number" },
1783         { 0,    NULL }
1784 };
1785
1786 static const value_string q931_numbering_plan_vals[] = {
1787         { 0x00, "Unknown" },
1788         { 0x01, "E.164 ISDN/telephony numbering" },
1789         { 0x03, "X.121 data numbering" },
1790         { 0x04, "F.69 Telex numbering" },
1791         { 0x08, "National standard numbering" },
1792         { 0x09, "Private numbering" },
1793         { 0,    NULL }
1794 };
1795
1796 static const value_string q931_presentation_indicator_vals[] = {
1797         { 0x00, "Presentation allowed" },
1798         { 0x20, "Presentation restricted" },
1799         { 0x40, "Number not available due to interworking" },
1800         { 0,    NULL }
1801 };
1802
1803 static const value_string q931_screening_indicator_vals[] = {
1804         { 0x00, "User-provided, not screened" },
1805         { 0x01, "User-provided, verified and passed" },
1806         { 0x02, "User-provided, verified and failed" },
1807         { 0x03, "Network-provided" },
1808         { 0,    NULL }
1809 };
1810
1811 static const value_string q931_redirection_reason_vals[] = {
1812         { 0x00, "Unknown" },
1813         { 0x01, "Call forwarding busy or called DTE busy" },
1814         { 0x02, "Call forwarding no reply" },
1815         { 0x04, "Call deflection" },
1816         { 0x09, "Called DTE out of order" },
1817         { 0x0A, "Call forwarding by the called DTE" },
1818         { 0x0F, "Call forwarding unconditional or systematic call redirection" },
1819         { 0,    NULL }
1820 };
1821
1822 static void
1823 dissect_q931_number_ie(tvbuff_t *tvb, int offset, int len,
1824     proto_tree *tree)
1825 {
1826         guint8 octet;
1827
1828         if (len == 0)
1829                 return;
1830         octet = tvb_get_guint8(tvb, offset);
1831         proto_tree_add_text(tree, tvb, offset, 1,
1832             "Type of number: %s",
1833             val_to_str(octet & 0x70, q931_number_type_vals,
1834               "Unknown (0x%02X)"));
1835         proto_tree_add_text(tree, tvb, offset, 1,
1836             "Numbering plan: %s",
1837             val_to_str(octet & 0x0F, q931_numbering_plan_vals,
1838               "Unknown (0x%02X)"));
1839         offset += 1;
1840         len -= 1;
1841
1842         if (!(octet & Q931_IE_VL_EXTENSION)) {
1843                 if (len == 0)
1844                         return;
1845                 octet = tvb_get_guint8(tvb, offset);
1846                 proto_tree_add_text(tree, tvb, offset, 1,
1847                     "Presentation indicator: %s",
1848                     val_to_str(octet & 0x60, q931_presentation_indicator_vals,
1849                       "Unknown (0x%X)"));
1850                 proto_tree_add_text(tree, tvb, offset, 1,
1851                     "Screening indicator: %s",
1852                     val_to_str(octet & 0x03, q931_screening_indicator_vals,
1853                       "Unknown (0x%X)"));
1854                 offset += 1;
1855                 len -= 1;
1856         }
1857
1858         /*
1859          * XXX - only in a Redirecting number information element.
1860          */
1861         if (!(octet & Q931_IE_VL_EXTENSION)) {
1862                 if (len == 0)
1863                         return;
1864                 octet = tvb_get_guint8(tvb, offset);
1865                 proto_tree_add_text(tree, tvb, offset, 1,
1866                     "Reason for redirection: %s",
1867                     val_to_str(octet & 0x0F, q931_redirection_reason_vals,
1868                       "Unknown (0x%X)"));
1869                 offset += 1;
1870                 len -= 1;
1871         }
1872
1873         if (len == 0)
1874                 return;
1875         proto_tree_add_text(tree, tvb, offset, len, "Number: %s",
1876             tvb_format_text(tvb, offset, len));
1877 }
1878
1879 /*
1880  * Dissect a party subaddress information element.
1881  */
1882 static const value_string q931_subaddress_type_vals[] = {
1883         { 0x00, "X.213/ISO 8348 Add.2 NSAP" },
1884         { 0x20, "User-specified" },
1885         { 0,    NULL }
1886 };
1887
1888 static const value_string q931_odd_even_indicator_vals[] = {
1889         { 0x00, "Even number of address signals" },
1890         { 0x10, "Odd number of address signals" },
1891         { 0,    NULL }
1892 };
1893
1894 static void
1895 dissect_q931_party_subaddr_ie(tvbuff_t *tvb, int offset, int len,
1896     proto_tree *tree)
1897 {
1898         guint8 octet;
1899
1900         if (len == 0)
1901                 return;
1902         octet = tvb_get_guint8(tvb, offset);
1903         proto_tree_add_text(tree, tvb, offset, 1,
1904             "Type of subaddress: %s",
1905             val_to_str(octet & 0x70, q931_subaddress_type_vals,
1906               "Unknown (0x%02X)"));
1907         proto_tree_add_text(tree, tvb, offset, 1,
1908             "Odd/even indicator: %s",
1909             val_to_str(octet & 0x10, q931_odd_even_indicator_vals,
1910               NULL));
1911         offset += 1;
1912         len -= 1;
1913
1914         if (len == 0)
1915                 return;
1916         proto_tree_add_text(tree, tvb, offset, len, "Subaddress: %s",
1917             tvb_bytes_to_str(tvb, offset, len));
1918 }
1919
1920 /*
1921  * Dissect a Restart indicator information element.
1922  */
1923 static const value_string q931_restart_indicator_class_vals[] = {
1924         { 0x00, "Indicated channels" },
1925         { 0x06, "Single interface" },
1926         { 0x07, "All interfaces" },
1927         { 0,    NULL }
1928 };
1929
1930 static void
1931 dissect_q931_restart_indicator_ie(tvbuff_t *tvb, int offset, int len,
1932     proto_tree *tree)
1933 {
1934         if (len != 1) {
1935                 proto_tree_add_text(tree, tvb, offset, len,
1936                     "Restart indicator: length is %d, should be 1\n", len);
1937                 return;
1938         }
1939         proto_tree_add_text(tree, tvb, offset, 1,
1940             "Restart indicator: %s",
1941             val_to_str(tvb_get_guint8(tvb, offset) & 0x07,
1942               q931_restart_indicator_class_vals, "Unknown (0x%02X)"));
1943 }
1944
1945 /*
1946  * Dissect a High-layer compatibility information element.
1947  */
1948 #define Q931_AUDIOVISUAL        0x60
1949 static const value_string q931_high_layer_characteristics_vals[] = {
1950         { 0x01,             "Telephony" },
1951         { 0x04,             "F.182 Facsimile Group 2/3" },
1952         { 0x21,             "F.184 Facsimile Group 4 Class I" },
1953         { 0x24,             "F.230 Teletex, basic and mixed mode, and F.184 Facsimile Group 4, Classes II and III" },
1954         { 0x28,             "F.220 Teletex, basic and processable mode" },
1955         { 0x31,             "F.200 Teletex, basic mode" },
1956         { 0x32,             "F.300 and T.102 syntax-based Videotex" },
1957         { 0x33,             "F.300 and T.101 international Videotex interworking" },
1958         { 0x35,             "F.60 Telex" },
1959         { 0x38,             "X.400 Message Handling Systems" },
1960         { 0x41,             "X.200 OSI application" },
1961         { 0x42,             "FTAM application" },
1962         { 0x5E,             "Reserved for maintenance" },
1963         { 0x5F,             "Reserved for management" },
1964         { Q931_AUDIOVISUAL, "F.720/F.821 and F.731 Profile 1a videotelephony" },
1965         { 0x61,             "F.702 and F.731 Profile 1b videoconferencing" },
1966         { 0x62,             "F.702 and F.731 audiographic conferencing" },
1967         { 0,                NULL }
1968 };
1969
1970 static const value_string q931_audiovisual_characteristics_vals[] = {
1971         { 0x01, "Capability set of initial channel of H.221" },
1972         { 0x02, "Capability set of subsequent channel of H.221" },
1973         { 0x21, "Capability set of initial channel of an active 3.1kHz audio or speech call" },
1974         { 0x00, NULL }
1975 };
1976
1977 void
1978 dissect_q931_high_layer_compat_ie(tvbuff_t *tvb, int offset, int len,
1979     proto_tree *tree)
1980 {
1981         guint8 octet;
1982         guint8 coding_standard;
1983         guint8 characteristics;
1984
1985         if (len == 0)
1986                 return;
1987         octet = tvb_get_guint8(tvb, offset);
1988         coding_standard = octet & 0x60;
1989         proto_tree_add_text(tree, tvb, offset, 1,
1990             "Coding standard: %s",
1991             val_to_str(coding_standard, q931_coding_standard_vals, NULL));
1992         if (coding_standard != Q931_ITU_STANDARDIZED_CODING) {
1993                 /*
1994                  * We don't know how the call state is encoded,
1995                  * so just dump it as data and be done with it.
1996                  */
1997                 proto_tree_add_text(tree, tvb, offset,
1998                     len, "Data: %s",
1999                     tvb_bytes_to_str(tvb, offset, len));
2000                 return;
2001         }
2002
2003         if (len == 0)
2004                 return;
2005         octet = tvb_get_guint8(tvb, offset);
2006         characteristics = octet & 0x7F;
2007         proto_tree_add_text(tree, tvb, offset, 1,
2008             "High layer characteristics identification: %s",
2009             val_to_str(characteristics, q931_high_layer_characteristics_vals,
2010              "Unknown (0x%02X)"));
2011         offset += 1;
2012         len -= 1;
2013
2014         if (!(octet & Q931_IE_VL_EXTENSION)) {
2015                 if (len == 0)
2016                         return;
2017                 octet = tvb_get_guint8(tvb, offset);
2018                 if (characteristics == Q931_AUDIOVISUAL) {
2019                         proto_tree_add_text(tree, tvb, offset, 1,
2020                             "Extended audiovisual characteristics identification: %s",
2021                             val_to_str(octet & 0x7F,
2022                               q931_audiovisual_characteristics_vals,
2023                               "Unknown (0x%02X)"));
2024                 } else {
2025                         proto_tree_add_text(tree, tvb, offset, 1,
2026                             "Extended high layer characteristics identification: %s",
2027                             val_to_str(octet & 0x7F,
2028                               q931_high_layer_characteristics_vals,
2029                               "Unknown (0x%02X)"));
2030                 }
2031         }
2032 }
2033
2034
2035 /*
2036  * Dissect a User-user information element.
2037  */
2038 #define Q931_PROTOCOL_DISCRIMINATOR_IA5 0x04
2039
2040 static const value_string q931_protocol_discriminator_vals[] = {
2041         { 0x00,                                 "User-specific protocol" },
2042         { 0x01,                                 "OSI high layer protocols" },
2043         { 0x02,                                 "X.244" },
2044         { Q931_PROTOCOL_DISCRIMINATOR_IA5,      "IA5 characters" },
2045         { 0x05,                                 "X.208 and X.209 coded user information" },
2046         { 0x07,                                 "V.120 rate adaption" },
2047         { 0x08,                                 "Q.931/I.451 user-network call control messages" },
2048         { 0,                                    NULL }
2049 };
2050
2051 static void
2052 dissect_q931_user_user_ie(tvbuff_t *tvb, int offset, int len,
2053     proto_tree *tree)
2054 {
2055         guint8 octet;
2056
2057         if (len == 0)
2058                 return;
2059         octet = tvb_get_guint8(tvb, offset);
2060         proto_tree_add_text(tree, tvb, offset, 1,
2061             "Protocol discriminator: %s",
2062             val_to_str(octet, q931_protocol_discriminator_vals,
2063             "Unknown (0x%02x)"));
2064         offset += 1;
2065         len -= 1;
2066
2067         if (len == 0)
2068                 return;
2069         switch (octet) {
2070
2071         case Q931_PROTOCOL_DISCRIMINATOR_IA5:
2072                 proto_tree_add_text(tree, tvb, offset, len, "User information: %s",
2073                     tvb_format_text(tvb, offset, len));
2074                 break;
2075
2076         default:
2077                 proto_tree_add_text(tree, tvb, offset, len, "User information: %s",
2078                     tvb_bytes_to_str(tvb, offset, len));
2079                 break;
2080         }
2081 }
2082
2083 /*
2084  * Dissect information elements consisting of ASCII^H^H^H^H^HIA5 text.
2085  */
2086 static void
2087 dissect_q931_ia5_ie(tvbuff_t *tvb, int offset, int len, proto_tree *tree,
2088     char *label)
2089 {
2090         if (len != 0) {
2091                 proto_tree_add_text(tree, tvb, offset, len, "%s: %s", label,
2092                     tvb_format_text(tvb, offset, len));
2093         }
2094 }
2095
2096 static const value_string q931_codeset_vals[] = {
2097         { 0x00, "Q.931 information elements" },
2098         { 0x04, "Information elements for ISO/IEC use" },
2099         { 0x05, "Information elements for national use" },
2100         { 0x06, "Information elements specific to the local network" },
2101         { 0x07, "User-specific information elements" },
2102         { 0x00, NULL },
2103 };
2104
2105 static gboolean
2106 q931_dissector(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
2107     gboolean started_heuristic)
2108 {
2109         int             offset = 0;
2110         guint           reported_length;
2111         proto_tree      *q931_tree = NULL;
2112         proto_item      *ti;
2113         proto_tree      *ie_tree;
2114         guint8          call_ref_len;
2115         guint8          call_ref[15];
2116         guint8          message_type;
2117         guint8          info_element;
2118         guint16         info_element_len;
2119         int             codeset;
2120         gboolean        non_locking_shift;
2121         guint8          protocol_discriminator;
2122
2123 #ifdef H323
2124         tvbuff_t        *h225_tvb;
2125         gboolean        is_h323_h225 = FALSE;
2126         /*
2127          * It is very much possible to find a TPKT header here
2128          * TPKT is defined in RFC 1009 as a wrapper around ISO
2129          * defined protocols. There could even be several TPKT
2130          * wrapped messages in one TCP data field...
2131          * XXXXXXXX THIS IS NOT IMPLEMENTED YET!!! XXXXXXXXXXX
2132          *
2133          * For Q.931 related messages this is easy. If a
2134          * protocol discriminator is found with a value of 3
2135          * and it's the first discriminator in the Q.931
2136          * message one can safely assume it to be a TPKT
2137          * header. See also Q.931 Table 4-1/Q.931
2138          */
2139 #endif
2140
2141         protocol_discriminator = tvb_get_guint8( tvb, offset );
2142             /* Keep the protocol discriminator for later use */
2143
2144 #ifdef H323
2145         if ( started_heuristic ) {
2146                 /*
2147                  * The heuristic Q.931 message should conform to this
2148                  */
2149                 if ( protocol_discriminator != NLPID_Q_931 )
2150                         return FALSE;
2151
2152                 if ( ! is_tpkt( tvb, &offset ) )
2153                         return FALSE;
2154
2155                 if ( tvb_length_remaining( tvb, offset ) <= 3 )
2156                         return FALSE;
2157         }
2158
2159         /*
2160          * The first byte should be < 8 (3 is TPKT, rest is Q.931)
2161          */
2162         if ( protocol_discriminator < 8 ) {
2163                 /*
2164                  * The minimum length of a Q.931 message is 3:
2165                  * 1 byte for the protocol discriminator,
2166                  * 1 for the call_reference length,
2167                  * and one for the message type.
2168                  */
2169                 if ( tvb_length_remaining( tvb, offset ) <= 3 )
2170                         return FALSE;
2171
2172                 /*
2173                  * OK, there are a couple of bytes available, but is there
2174                  * also a protocol discriminator?
2175                  */
2176                 if ( tvb_length_remaining( tvb, offset ) > 3 ) {
2177                         /* Reread the protocol discriminator */
2178                         protocol_discriminator =
2179                             tvb_get_guint8( tvb, offset + 4);
2180                 } else {
2181                       /* No discriminator available */
2182                       protocol_discriminator = 0;
2183                 }
2184
2185                 /*
2186                  * If it's not H.323 related Q.931 no heuristic action needed
2187                  * Dangerous, there might be other uses for this code.....
2188                  */
2189                 if ( ( started_heuristic ) && (protocol_discriminator != 8 ) )
2190                         return FALSE;
2191
2192                 /*
2193                  * Always check if it's a real TPKT message
2194                  */
2195                 if ( ! is_tpkt( tvb, &offset ) )
2196                         return FALSE;
2197
2198                 dissect_tpkt( tvb, &offset, pinfo, tree );
2199
2200                 /*
2201                  * Reset the current_proto variable because dissect_tpkt
2202                  * messed with it
2203                  */
2204                 if ( started_heuristic )
2205                         pinfo->current_proto = "Q.931 HEUR";
2206                 else
2207                         pinfo->current_proto = "Q.931";
2208         }
2209 #endif
2210
2211         /*
2212          * The minimum length of a Q.931 message is
2213          * 3, 1 byte for the protocol discr. 1 for the call_reference length,
2214          * and one for the message type.
2215          */
2216         if ( tvb_length_remaining( tvb, offset ) <= 3 ) {
2217                 return FALSE;
2218         }
2219
2220         if (check_col(pinfo->fd, COL_PROTOCOL))
2221                 col_set_str(pinfo->fd, COL_PROTOCOL, "Q.931");
2222
2223         if (tree) {
2224                 ti = proto_tree_add_item(tree, proto_q931, tvb, offset,
2225                     tvb_length(tvb), FALSE);
2226                 q931_tree = proto_item_add_subtree(ti, ett_q931);
2227
2228                 dissect_q931_protocol_discriminator( tvb, offset, q931_tree );
2229         }
2230         offset += 1;
2231         call_ref_len = tvb_get_guint8(tvb, offset) & 0xF;       /* XXX - do as a bit field? */
2232         if (q931_tree != NULL)
2233                 proto_tree_add_uint(q931_tree, hf_q931_call_ref_len, tvb, offset, 1, call_ref_len);
2234         offset += 1;
2235         if (call_ref_len != 0) {
2236                 /* XXX - split this into flag and value */
2237                 tvb_memcpy(tvb, call_ref, offset, call_ref_len);
2238                 if (q931_tree != NULL)
2239                         proto_tree_add_bytes(q931_tree, hf_q931_call_ref, tvb, offset, call_ref_len, call_ref);
2240                 offset += call_ref_len;
2241         }
2242         message_type = tvb_get_guint8(tvb, offset);
2243         if (check_col(pinfo->fd, COL_INFO)) {
2244                 col_add_str(pinfo->fd, COL_INFO,
2245                     val_to_str(message_type, q931_message_type_vals,
2246                       "Unknown message type (0x%02X)"));
2247         }
2248         if (q931_tree != NULL)
2249                 proto_tree_add_uint(q931_tree, hf_q931_message_type, tvb, offset, 1, message_type);
2250         offset += 1;
2251
2252         /*
2253          * And now for the information elements....
2254          */
2255         codeset = 0;    /* start out in codeset 0 */
2256         non_locking_shift = TRUE;
2257         reported_length = tvb_reported_length(tvb);
2258         while (offset < reported_length) {
2259                 info_element = tvb_get_guint8(tvb, offset);
2260
2261                 /*
2262                  * Check for the single-octet IEs.
2263                  */
2264                 switch (info_element & Q931_IE_SO_IDENTIFIER_MASK) {
2265
2266                 case Q931_IE_SHIFT:
2267                         non_locking_shift =
2268                             !(info_element & Q931_IE_SHIFT_LOCKING);
2269                         codeset = info_element & Q931_IE_SHIFT_CODESET;
2270                         if (q931_tree != NULL) {
2271                                 proto_tree_add_text(q931_tree, tvb, offset, 1,
2272                                     "%s shift to codeset %u: %s",
2273                                     (non_locking_shift ? "Non-locking" : "Locking"),
2274                                     codeset,
2275                                     val_to_str(codeset, q931_codeset_vals,
2276                                       "Unknown (0x%02X)"));
2277                         }
2278                         offset += 1;
2279                         continue;
2280
2281                 case Q931_IE_MORE_DATA_OR_SEND_COMP:
2282                         switch (info_element) {
2283
2284                         case Q931_IE_MORE_DATA:
2285                                 if (q931_tree != NULL) {
2286                                         proto_tree_add_text(q931_tree, tvb, offset, 1,
2287                                             "More data");
2288                                 }
2289                                 break;
2290
2291                         case Q931_IE_SENDING_COMPLETE:
2292                                 if (q931_tree != NULL) {
2293                                         proto_tree_add_text(q931_tree, tvb, offset, 1,
2294                                             "Sending complete");
2295                                 }
2296                                 break;
2297
2298                         default:
2299                                 if (q931_tree != NULL) {
2300                                         proto_tree_add_text(q931_tree, tvb, offset, 1,
2301                                             "Unknown information element (0x%02X",
2302                                             info_element);
2303                                 }
2304                                 break;
2305                         }
2306                         offset += 1;
2307                         if (non_locking_shift)
2308                                 codeset = 0;
2309                         continue;
2310
2311                 case Q931_IE_CONGESTION_LEVEL:
2312                         if (q931_tree != NULL) {
2313                                 proto_tree_add_text(q931_tree, tvb, offset, 1,
2314                                     "Congestion level: %s",
2315                                     val_to_str(info_element & Q931_IE_SO_IE_MASK,
2316                                       q931_congestion_level_vals,
2317                                       "Unknown (0x%X)"));
2318                         }
2319                         offset += 1;
2320                         if (non_locking_shift)
2321                                 codeset = 0;
2322                         continue;
2323
2324                 case Q931_IE_REPEAT_INDICATOR:
2325                         if (q931_tree != NULL) {
2326                                 proto_tree_add_text(q931_tree, tvb, offset, 1,
2327                                     "Repeat indicator: %s",
2328                                     val_to_str(info_element & Q931_IE_SO_IE_MASK,
2329                                       q931_repeat_indication_vals,
2330                                       "Unknown (0x%X)"));
2331                         }
2332                         offset += 1;
2333                         if (non_locking_shift)
2334                                 codeset = 0;
2335                         continue;
2336
2337                 default:
2338                         break;
2339                 }
2340
2341                 /*
2342                  * Variable-length IE.
2343                  */
2344 #ifndef H323
2345                 info_element_len = tvb_get_guint8(tvb, offset + 1);
2346 #else
2347                 /*
2348                  * According to page 18 from Recommendation H.225.0 :
2349                  * " Length of user-user contents contents
2350                  * - Shall be 2 octets instead of 1 (as in Figure 4-36/Q.931)"
2351                  *
2352                  * This will be true for all messages going to / from TCP port
2353                  * 1720 and with the first and fourth octet of the user-user
2354                  * IE having the values 0x7E and 0x05 resp.
2355                  * See http://www.mbuf.org/~moto/h323/h323decoder.html
2356                  *
2357                  */
2358
2359                 if ( ( tvb_get_guint8( tvb, offset ) == 0x7E ) &&
2360                    ( tvb_get_guint8( tvb, offset + 3 ) == 0x05 ) &&
2361                    /* ( ( pi.srcport == 1720 ) || ( pi.destport == 1720 ) ) && */
2362                    ( protocol_discriminator == NLPID_Q_931 ) )  {
2363                         info_element_len = tvb_get_ntohs( tvb, offset + 1 );
2364                         is_h323_h225 = TRUE;
2365                         if ( tree == NULL ) {
2366                                 h225_tvb = tvb_new_subset( tvb, offset + 4, info_element_len - 1, info_element_len - 1 );
2367                                 dissect_h225_cs( h225_tvb, pinfo, tree );
2368                                 /*
2369                                  * Skip the 4 bytes of the element header and then the element itself
2370                                  */
2371                                 offset += 4;
2372                                 offset += info_element_len - 1;
2373                         }
2374                 } else {
2375                         info_element_len = tvb_get_guint8( tvb, offset + 1 );
2376                 }
2377 #endif
2378                 if (q931_tree != NULL) {
2379 #ifdef H323
2380                         if (is_h323_h225) {
2381                                 ti = proto_tree_add_text(q931_tree, tvb, offset,
2382                                     1+1+1, "%s",
2383                                     val_to_str(info_element,
2384                                       q931_info_element_vals,
2385                                       "Unknown information element (0x%02X)"));
2386                                 ie_tree = proto_item_add_subtree(ti,
2387                                     ett_q931_ie);
2388                                 proto_tree_add_text(ie_tree, tvb, offset, 1,
2389                                     "Information element: %s",
2390                                     val_to_str(info_element,
2391                                       q931_info_element_vals, "Unknown (0x%02X)"));
2392                                 proto_tree_add_text(ie_tree, tvb, offset + 1,
2393                                     2, "Length: %u", info_element_len);
2394                         } else {
2395 #endif
2396                                 ti = proto_tree_add_text(q931_tree, tvb, offset,
2397                                     1+1+info_element_len, "%s",
2398                                     val_to_str(info_element, q931_info_element_vals,
2399                                       "Unknown information element (0x%02X)"));
2400                                         ie_tree = proto_item_add_subtree(ti, ett_q931_ie);
2401                                 proto_tree_add_text(ie_tree, tvb, offset, 1,
2402                                     "Information element: %s",
2403                                     val_to_str(info_element, q931_info_element_vals,
2404                                       "Unknown (0x%02X)"));
2405                                 proto_tree_add_text(ie_tree, tvb, offset + 1, 1,
2406                                     "Length: %u", info_element_len);
2407 #ifdef H323
2408                         }
2409 #endif
2410                         switch (info_element) {
2411
2412                         case Q931_IE_SEGMENTED_MESSAGE:
2413                                 dissect_q931_segmented_message_ie(tvb,
2414                                     offset + 2, info_element_len, ie_tree);
2415                                 break;
2416
2417                         case Q931_IE_BEARER_CAPABILITY:
2418                         case Q931_IE_LOW_LAYER_COMPAT:
2419                                 dissect_q931_bearer_capability_ie(tvb,
2420                                     offset + 2, info_element_len, ie_tree);
2421                                 break;
2422
2423                         case Q931_IE_CAUSE:
2424                                 dissect_q931_cause_ie(tvb,
2425                                     offset + 2, info_element_len, ie_tree);
2426                                 break;
2427
2428                         case Q931_IE_CALL_STATE:
2429                                 dissect_q931_call_state_ie(tvb,
2430                                     offset + 2, info_element_len, ie_tree);
2431                                 break;
2432
2433                         case Q931_IE_CHANNEL_IDENTIFICATION:
2434                                 dissect_q931_channel_identification_ie(tvb,
2435                                     offset + 2, info_element_len, ie_tree);
2436                                 break;
2437
2438                         case Q931_IE_PROGRESS_INDICATOR:
2439                                 dissect_q931_progress_indicator_ie(tvb,
2440                                     offset + 2, info_element_len, ie_tree);
2441                                 break;
2442
2443                         case Q931_IE_NETWORK_SPECIFIC_FACIL:
2444                         case Q931_IE_TRANSIT_NETWORK_SEL:
2445                                 dissect_q931_ns_facilities_ie(tvb,
2446                                     offset + 2, info_element_len, ie_tree);
2447                                 break;
2448
2449                         case Q931_IE_NOTIFICATION_INDICATOR:
2450                                 dissect_q931_notification_indicator_ie(tvb,
2451                                     offset + 2, info_element_len, ie_tree);
2452                                 break;
2453
2454                         case Q931_IE_DISPLAY:
2455                                 dissect_q931_ia5_ie(tvb, offset + 2,
2456                                     info_element_len, ie_tree,
2457                                     "Display information");
2458                                 break;
2459
2460                         case Q931_IE_DATE_TIME:
2461                                 dissect_q931_date_time_ie(tvb,
2462                                     offset + 2, info_element_len, ie_tree);
2463                                 break;
2464
2465                         case Q931_IE_KEYPAD_FACILITY:
2466                                 dissect_q931_ia5_ie(tvb, offset + 2,
2467                                     info_element_len, ie_tree,
2468                                     "Keypad facility");
2469                                 break;
2470
2471                         case Q931_IE_SIGNAL:
2472                                 dissect_q931_signal_ie(tvb,
2473                                     offset + 2, info_element_len, ie_tree);
2474                                 break;
2475
2476                         case Q931_IE_INFORMATION_RATE:
2477                                 dissect_q931_information_rate_ie(tvb,
2478                                     offset + 2, info_element_len, ie_tree);
2479                                 break;
2480
2481                         case Q931_IE_E2E_TRANSIT_DELAY:
2482                                 dissect_q931_e2e_transit_delay_ie(tvb,
2483                                     offset + 2, info_element_len, ie_tree);
2484                                 break;
2485
2486                         case Q931_IE_TD_SELECTION_AND_INT:
2487                                 dissect_q931_td_selection_and_int_ie(tvb,
2488                                     offset + 2, info_element_len, ie_tree);
2489                                 break;
2490
2491                         case Q931_IE_PL_BINARY_PARAMETERS:
2492                                 dissect_q931_pl_binary_parameters_ie(tvb,
2493                                     offset + 2, info_element_len, ie_tree);
2494                                 break;
2495
2496                         case Q931_IE_PL_WINDOW_SIZE:
2497                                 dissect_q931_pl_window_size_ie(tvb,
2498                                     offset + 2, info_element_len, ie_tree);
2499                                 break;
2500
2501                         case Q931_IE_PACKET_SIZE:
2502                                 dissect_q931_packet_size_ie(tvb,
2503                                     offset + 2, info_element_len, ie_tree);
2504                                 break;
2505
2506                         case Q931_IE_CUG:
2507                                 dissect_q931_cug_ie(tvb,
2508                                     offset + 2, info_element_len, ie_tree);
2509                                 break;
2510
2511                         case Q931_IE_REVERSE_CHARGE_IND:
2512                                 dissect_q931_reverse_charge_ind_ie(tvb,
2513                                     offset + 2, info_element_len, ie_tree);
2514                                 break;
2515
2516                         case Q931_IE_CALLING_PARTY_NUMBER:
2517                         case Q931_IE_CALLED_PARTY_NUMBER:
2518                         case Q931_IE_REDIRECTING_NUMBER:
2519                                 dissect_q931_number_ie(tvb,
2520                                     offset + 2, info_element_len, ie_tree);
2521                                 break;
2522
2523                         case Q931_IE_CALLING_PARTY_SUBADDR:
2524                         case Q931_IE_CALLED_PARTY_SUBADDR:
2525                                 dissect_q931_party_subaddr_ie(tvb,
2526                                     offset + 2, info_element_len, ie_tree);
2527                                 break;
2528
2529                         case Q931_IE_RESTART_INDICATOR:
2530                                 dissect_q931_restart_indicator_ie(tvb,
2531                                     offset + 2, info_element_len, ie_tree);
2532                                 break;
2533
2534                         case Q931_IE_HIGH_LAYER_COMPAT:
2535                                 dissect_q931_high_layer_compat_ie(tvb,
2536                                     offset + 2, info_element_len, ie_tree);
2537                                 break;
2538
2539                         case Q931_IE_USER_USER:
2540 #ifdef H323
2541                                 if (is_h323_h225) {
2542                                         h225_tvb = tvb_new_subset(tvb,
2543                                             offset + 4, info_element_len - 1,
2544                                             info_element_len - 1);
2545                                         dissect_h225_cs(h225_tvb, pinfo, tree);
2546                                         offset += 3;
2547                                         proto_tree_add_text(ie_tree, tvb,
2548                                             offset, 1,
2549                                             "Protocol discriminator: %s",
2550                                             val_to_str(tvb_get_guint8(tvb, offset),
2551                                               q931_protocol_discriminator_vals,
2552                                               "Unknown (0x%02x)"));
2553                                         offset += info_element_len;
2554                                 } else {
2555 #endif
2556                                         dissect_q931_user_user_ie(tvb,
2557                                             offset + 2, info_element_len,
2558                                             ie_tree);
2559 #ifdef H323
2560                                 }
2561 #endif
2562                                 break;
2563
2564                         default:
2565                                 proto_tree_add_text(ie_tree, tvb, offset + 2,
2566                                     info_element_len, "Data: %s",
2567                                     bytes_to_str(
2568                                       tvb_get_ptr(tvb, offset + 2, info_element_len),
2569                                       info_element_len));
2570                                 break;
2571                         }
2572                 }
2573                 offset += 1 + 1 + info_element_len;
2574                 if (non_locking_shift)
2575                         codeset = 0;
2576         }
2577
2578         /*
2579          * Heuristic should return TRUE if it get's here.
2580          */
2581
2582         return TRUE;
2583
2584 }
2585
2586 #ifdef H323
2587 gboolean
2588 dissect_q931_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
2589 {
2590         /*
2591          * XXX - should this be heuristic, or should we just make
2592          * port 1720 do Q.931-inside-TPKT; that port appears to be
2593          * intended for H.323 calls, according to
2594          *
2595          *      http://www.isi.edu/in-notes/iana/assignments/port-numbers
2596          *
2597          * which says it's for "h323hostcall"?
2598          */
2599         pinfo->current_proto = "Q.931 HEUR";
2600         return q931_dissector(tvb, pinfo, tree, TRUE);
2601 }
2602 #endif
2603
2604 void
2605 dissect_q931(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
2606 {
2607         pinfo->current_proto = "Q.931";
2608         q931_dissector(tvb, pinfo, tree, FALSE);
2609 }
2610
2611 void
2612 proto_register_q931(void)
2613 {
2614         static hf_register_info hf[] = {
2615                 { &hf_q931_discriminator,
2616                   { "Protocol discriminator", "q931.disc", FT_UINT8, BASE_HEX, NULL, 0x0,
2617                         "" }},
2618
2619                 { &hf_q931_call_ref_len,
2620                   { "Call reference value length", "q931.call_ref_len", FT_UINT8, BASE_DEC, NULL, 0x0,
2621                         "" }},
2622
2623                 { &hf_q931_call_ref,
2624                   { "Call reference value", "q931.call_ref", FT_BYTES, BASE_HEX, NULL, 0x0,
2625                         "" }},
2626
2627                 { &hf_q931_message_type,
2628                   { "Message type", "q931.message_type", FT_UINT8, BASE_HEX, VALS(q931_message_type_vals), 0x0,
2629                         "" }},
2630
2631             };
2632         static gint *ett[] = {
2633                 &ett_q931,
2634                 &ett_q931_ie,
2635         };
2636
2637         proto_q931 = proto_register_protocol ("Q.931", "q931");
2638         proto_register_field_array (proto_q931, hf, array_length(hf));
2639         proto_register_subtree_array(ett, array_length(ett));
2640
2641 }
2642
2643 void
2644 proto_reg_handoff_q931(void)
2645 {
2646 #ifdef H323
2647         heur_dissector_add("tcp", dissect_q931_heur);
2648 #endif
2649 }