epan/dissectors/packet-pw-cesopsn.c

   1 /* packet-pw-satop.c
   2  * Routines for CESoPSN PW dissection as per RFC5086.
   3  * Copyright 2009, Dmitry Trebich, Artem Tamazov <artem.tamazov@tellabs.com>
   4  *
   5  * $Id$
   6  *
   7  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; either version 2
  14  * of the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  24  *
  25  * History:
  26  * ---------------------------------
  27  * 16.03.2009 initial implementation for MPLS
  28  * 14.08.2009 added: support for IP/UDP demultiplexing
  29  * Not supported yet:
  30  * - All PW modes, except Basic NxDS0 mode.
  31  * - <Optional> RTP Headers (RFC3550)
  32  * - Decoding of PW payload
  33  */
  34
  35 #ifdef HAVE_CONFIG_H
  36 # include "config.h"
  37 #endif
  38
  39 #include <stdlib.h>
  40 #include <glib.h>
  41 #include <epan/packet.h>
  42 #include <epan/expert.h>
  43
  44 #include "packet-mpls.h"
  45 #include "packet-pw-common.h"
  46
  47 static gint proto = -1;
  48 static gint ett = -1;
  49
  50 static int hf_cw = -1;
  51 static int hf_cw_bits03 = -1;
  52 static int hf_cw_lm = -1;
  53 static int hf_cw_r = -1;
  54 static int hf_cw_frg = -1;
  55 static int hf_cw_len = -1;
  56 static int hf_cw_seq = -1;
  57 static int hf_payload = -1;
  58 static int hf_payload_l = -1;
  59
  60 static dissector_handle_t data_handle;
  61 static dissector_handle_t pw_padding_handle;
  62
  63 const char pwc_longname_pw_cesopsn[] = "CESoPSN basic NxDS0 mode (no RTP support)";
  64 static const char shortname[] = "CESoPSN basic (no RTP)";
  65
  66 static const value_string vals_cw_lm[] = {
  67         /* note that bitmask in hs_register_info is 0xb == 1011B */
  68         /* this is why 0x8 comes just after 0x3 */
  69         { 0x0,  "Normal situation - no AC faults" },
  70         /*{ 0x1,        "Reserved combination" },*/
  71         { 0x2,  "AC Fault - RDI condition" },
  72         { 0x3,  "Reserved for CESoPSN signaling" },
  73         { 0x8,  "AC Fault - TDM data is invalid" },
  74         /*{ 0x9,        "Reserved combination" },*/
  75         /*{ 0xa,        "Reserved combination" },*/
  76         /*{ 0xb,        "Reserved combination" },*/
  77         { 0,    NULL }
  78 };
  79
  80
  81 static
  82 void dissect_pw_cesopsn( tvbuff_t * tvb_original
  83                                                 ,packet_info * pinfo
  84                                                 ,proto_tree * tree
  85                                                 ,pwc_demux_type_t demux)
  86 {
  87         const int encaps_size = 4; /*RTP header in encapsulation is not supported yet*/
  88         gint packet_size;
  89         gint payload_size;
  90         gint padding_size;
  91         pwc_packet_properties_t properties;
  92
  93         packet_size = tvb_reported_length_remaining(tvb_original, 0);
  94
  95         /*
  96          * FIXME
  97          * "4" below should be replaced by something like "min_packet_size_this_dissector"
  98          * Also call to dissect_try_cw_first_nibble() should be moved before this block
  99          */
 100         if (packet_size < 4) /* 4 is smallest size which may be sensible (for PWACH dissector) */
 101         {
 102                 if (tree)
 103                 {
 104                         proto_item  *item;
 105                         item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
 106                         expert_add_info_format(pinfo, item, PI_MALFORMED, PI_ERROR,
 107                                 "PW packet size (%d) is too small to carry sensible information"
 108                                 ,(int)packet_size);
 109                 }
 110                 if (check_col(pinfo->cinfo, COL_PROTOCOL))
 111                 {
 112                         col_set_str(pinfo->cinfo, COL_PROTOCOL, shortname);
 113                 }
 114                 col_set_str(pinfo->cinfo, COL_INFO, "Malformed: PW packet is too small");
 115                 return;
 116         }
 117
 118         switch (demux)
 119         {
 120         case PWC_DEMUX_MPLS:
 121                 if (dissect_try_cw_first_nibble(tvb_original, pinfo, tree))
 122                 {
 123                         return;
 124                 }
 125                 break;
 126         case PWC_DEMUX_UDP:
 127                 break;
 128         default:
 129                 DISSECTOR_ASSERT_NOT_REACHED();
 130                 return;
 131         }
 132
 133         /* check how "good" is this packet */
 134         /* also decide payload length from packet size and CW */
 135         properties = PWC_PACKET_PROPERTIES_T_INITIALIZER;
 136         if (0 != (tvb_get_guint8(tvb_original, 0) & 0xf0 /*bits03*/))
 137         {
 138                 properties |= PWC_CW_BAD_BITS03;
 139         }
 140         if (0 != (tvb_get_guint8(tvb_original, 1) & 0xc0 /*frag*/))
 141         {
 142                 properties |= PWC_CW_BAD_FRAG;
 143         }
 144         {
 145                 /* RFC5086:
 146                  * [LEN (bits (10 to 15) MAY be used to carry the length of the CESoPSN
 147                  * packet (defined as the size of the CESoPSN header + the payload size)
 148                  * if it is less than 64 bytes, and MUST be set to zero otherwise.
 149                  * Note:  If fixed RTP header is used in the encapsulation, it is
 150                  * considered part of the CESoPSN header.]
 151                  *
 152                  * Note that this differs from RFC4385's definition of length:
 153                  * [ If the MPLS payload is less than 64 bytes, the length field
 154                  * MUST be set to the length of the PW payload...]
 155                  *
 156                  * We will use RFC5086's definition here.
 157                  */
 158                 int cw_len;
 159                 gint payload_size_from_packet;
 160
 161                 cw_len = tvb_get_guint8(tvb_original, 1) & 0x3f;
 162                 payload_size_from_packet = packet_size - encaps_size;
 163                 if (cw_len != 0)
 164                 {
 165                         gint payload_size_from_cw;
 166                         payload_size_from_cw = cw_len - encaps_size;
 167                         /*
 168                          * Assumptions for error case,
 169                          * will be overwritten if no errors found:
 170                          */
 171                         payload_size = payload_size_from_packet;
 172                         padding_size = 0;
 173
 174                         if (payload_size_from_cw < 0)
 175                         {
 176                                 properties |= PWC_CW_BAD_PAYLEN_LT_0;
 177                         }
 178                         else if (payload_size_from_cw > payload_size_from_packet)
 179                         {
 180                                 properties |= PWC_CW_BAD_PAYLEN_GT_PACKET;
 181                         }
 182                         else if (payload_size_from_packet >= 64)
 183                         {
 184                                 properties |= PWC_CW_BAD_LEN_MUST_BE_0;
 185                         }
 186                         else /* ok */
 187                         {
 188                                 payload_size = payload_size_from_cw;
 189                                 padding_size = payload_size_from_packet - payload_size_from_cw; /* >=0 */
 190                         }
 191                 }
 192                 else
 193                 {
 194                         payload_size = payload_size_from_packet;
 195                         padding_size = 0;
 196                 }
 197         }
 198
 199         {
 200                 guint8 cw_lm;
 201                 cw_lm = tvb_get_guint8(tvb_original, 0) & 0x0b /*l+mod*/;
 202                 if (NULL == match_strval(cw_lm, vals_cw_lm))
 203                 {
 204                         properties |= PWC_CW_SUSPECT_LM;
 205                 }
 206
 207                 {
 208                         guint8 l_bit, m_bits;
 209                         l_bit  = (cw_lm & 0x08) >> 3;
 210                         m_bits = (cw_lm & 0x03) >> 0;
 211                         if ((l_bit == 0 && m_bits == 0x0) /*CESoPSN data packet - normal situation*/
 212                             ||(l_bit == 0 && m_bits == 0x2) /*CESoPSN data packet - RDI on the AC*/ )
 213                         {
 214                                 if ((payload_size == 0) || ((payload_size % 8) != 0))
 215                                 {
 216                                         properties |= PWC_PAY_SIZE_BAD;
 217                                 }
 218                         }
 219                         else if (l_bit == 1 && m_bits == 0x0) /*TDM data is invalid; payload MAY be omitted*/
 220                         {
 221                                 /*allow any size of payload*/
 222                         }
 223                         else /*reserved combinations*/
 224                         {
 225                                 /*allow any size of payload*/
 226                         }
 227                 }
 228         }
 229
 230         /* fill up columns*/
 231         if (check_col(pinfo->cinfo, COL_PROTOCOL))
 232         {
 233                 col_set_str(pinfo->cinfo, COL_PROTOCOL, shortname);
 234         }
 235         if (check_col(pinfo->cinfo, COL_INFO))
 236         {
 237                 col_clear(pinfo->cinfo, COL_INFO);
 238                 if (properties & PWC_ANYOF_CW_BAD)
 239                 {
 240                         col_append_str(pinfo->cinfo, COL_INFO, "CW:Bad, ");
 241                 }
 242                 else if (properties & PWC_ANYOF_CW_SUSPECT)
 243                 {
 244                         col_append_str(pinfo->cinfo, COL_INFO, "CW:Suspect, ");
 245                 }
 246
 247                 if (properties & PWC_PAY_SIZE_BAD)
 248                 {
 249                         col_append_str(pinfo->cinfo, COL_INFO, "Payload size:Bad, ");
 250                 }
 251
 252                 col_append_fstr(pinfo->cinfo, COL_INFO, "TDM octets:%d", (int)payload_size);
 253
 254                 if (padding_size != 0)
 255                 {
 256                         col_append_fstr(pinfo->cinfo, COL_INFO, ", Padding:%d", (int)padding_size);
 257                 }
 258         }
 259
 260         {
 261                 proto_item* item;
 262                 item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
 263                 pwc_item_append_cw(item,tvb_get_ntohl(tvb_original, 0),TRUE);
 264                 pwc_item_append_text_n_items(item,(int)payload_size,"octet");
 265                 {
 266                         proto_tree* tree2;
 267                         tree2 = proto_item_add_subtree(item, ett);
 268                         {
 269                                 tvbuff_t* tvb;
 270                                 proto_item* item2;
 271                                 tvb = tvb_new_subset(tvb_original, 0, PWC_SIZEOF_CW, PWC_SIZEOF_CW);
 272                                 item2 = proto_tree_add_item(tree2, hf_cw, tvb, 0, -1, ENC_NA);
 273                                 pwc_item_append_cw(item2,tvb_get_ntohl(tvb, 0),FALSE);
 274                                 {
 275                                         proto_tree* tree3;
 276                                         tree3 = proto_item_add_subtree(item, ett);
 277                                         {
 278                                                 proto_item* item3;
 279                                                 if (properties & PWC_CW_BAD_BITS03) /*display only if value is wrong*/
 280                                                 {
 281                                                         item3 = proto_tree_add_item(tree3, hf_cw_bits03, tvb, 0, 1, ENC_BIG_ENDIAN);
 282                                                         expert_add_info_format(pinfo, item3, PI_MALFORMED, PI_ERROR
 283                                                                 ,"Bits 0..3 of Control Word must be 0");
 284                                                 }
 285
 286                                                 item3 = proto_tree_add_item(tree3, hf_cw_lm,  tvb, 0, 1, ENC_BIG_ENDIAN);
 287                                                 if (properties & PWC_CW_SUSPECT_LM)
 288                                                 {
 289                                                         expert_add_info_format(pinfo, item3, PI_UNDECODED, PI_WARN
 290                                                                 ,"Reserved combination of L and Modifier bits");
 291                                                 }
 292
 293                                                 proto_tree_add_item(tree3, hf_cw_r, tvb, 0, 1, ENC_BIG_ENDIAN);
 294
 295                                                 item3 = proto_tree_add_item(tree3, hf_cw_frg, tvb, 1, 1, ENC_BIG_ENDIAN);
 296                                                 if (properties & PWC_CW_BAD_FRAG)
 297                                                 {
 298                                                         expert_add_info_format(pinfo, item3, PI_MALFORMED, PI_ERROR
 299                                                                 ,"Fragmentation of payload is not allowed"
 300                                                                 " for basic CESoPSN mode");
 301                                                 }
 302
 303                                                 item3 = proto_tree_add_item(tree3, hf_cw_len, tvb, 1, 1, ENC_BIG_ENDIAN);
 304                                                 if (properties & PWC_CW_BAD_PAYLEN_LT_0)
 305                                                 {
 306                                                         expert_add_info_format(pinfo, item3, PI_MALFORMED, PI_ERROR
 307                                                                 ,"Bad Length: too small, must be > %d"
 308                                                                 ,(int)encaps_size);
 309                                                 }
 310                                                 if (properties & PWC_CW_BAD_PAYLEN_GT_PACKET)
 311                                                 {
 312                                                         expert_add_info_format(pinfo, item3, PI_MALFORMED, PI_ERROR
 313                                                                 ,"Bad Length: must be <= than PSN packet size (%d)"
 314                                                                 ,(int)packet_size);
 315                                                 }
 316                                                 if (properties & PWC_CW_BAD_LEN_MUST_BE_0)
 317                                                 {
 318                                                         expert_add_info_format(pinfo, item3, PI_MALFORMED, PI_ERROR
 319                                                                 ,"Bad Length: must be 0 if CESoPSN packet size (%d) is > 64"
 320                                                                 ,(int)packet_size);
 321                                                 }
 322
 323                                                 proto_tree_add_item(tree3, hf_cw_seq, tvb, 2, 2, ENC_BIG_ENDIAN);
 324
 325                                         }
 326                                 }
 327                         }
 328                 }
 329
 330                 /* payload */
 331                 if (payload_size == 0)
 332                 {
 333                         if (properties & PWC_PAY_SIZE_BAD)
 334                         {
 335                                 expert_add_info_format(pinfo, item, PI_MALFORMED, PI_ERROR
 336                                         ,"CESoPSN payload: none found. Size of payload must be <> 0");
 337                         }
 338                         else
 339                         {
 340                                 expert_add_info_format(pinfo, item, PI_UNDECODED, PI_NOTE
 341                                         ,"CESoPSN payload: omitted to conserve bandwidth");
 342                         }
 343                 }
 344                 else
 345                 {
 346                         proto_tree* tree2;
 347                         tree2 = proto_item_add_subtree(item, ett);
 348                         {
 349                                 proto_item* item2;
 350                                 tvbuff_t* tvb;
 351                                 tvb = tvb_new_subset(tvb_original, PWC_SIZEOF_CW, payload_size, payload_size);
 352                                 item2 = proto_tree_add_item(tree2, hf_payload, tvb, 0, -1, ENC_NA);
 353                                 pwc_item_append_text_n_items(item2,(int)payload_size,"octet");
 354                                 if (properties & PWC_PAY_SIZE_BAD)
 355                                 {
 356                                         expert_add_info_format(pinfo, item2, PI_MALFORMED, PI_ERROR
 357                                                 ,"CESoPSN packet payload size must be multiple of 8");
 358                                 }
 359                                 tree2 = proto_item_add_subtree(item2, ett);
 360                                 call_dissector(data_handle, tvb, pinfo, tree2);
 361                                 item2 = proto_tree_add_int(tree2, hf_payload_l, tvb, 0, 0
 362                                         ,(int)payload_size); /* allow filtering */
 363                                 PROTO_ITEM_SET_HIDDEN(item2);
 364                         }
 365                 }
 366
 367                 /* padding */
 368                 if (padding_size > 0)
 369                 {
 370                         proto_tree* tree2;
 371                         tree2 = proto_item_add_subtree(item, ett);
 372                         {
 373                                 tvbuff_t* tvb;
 374                                 tvb = tvb_new_subset(tvb_original, PWC_SIZEOF_CW + payload_size, padding_size, -1);
 375                                 call_dissector(pw_padding_handle, tvb, pinfo, tree2);
 376                         }
 377                 }
 378         }
 379         return;
 380 }
 381
 382
 383 static
 384 void dissect_pw_cesopsn_mpls( tvbuff_t * tvb_original, packet_info * pinfo, proto_tree * tree)
 385 {
 386         dissect_pw_cesopsn(tvb_original,pinfo,tree,PWC_DEMUX_MPLS);
 387         return;
 388 }
 389
 390
 391 static
 392 void dissect_pw_cesopsn_udp( tvbuff_t * tvb_original, packet_info * pinfo, proto_tree * tree)
 393 {
 394         dissect_pw_cesopsn(tvb_original,pinfo,tree,PWC_DEMUX_UDP);
 395         return;
 396 }
 397
 398
 399 void proto_register_pw_cesopsn(void)
 400 {
 401         static hf_register_info hf[] = {
 402                 { &hf_cw        ,{"Control Word"                ,"pwcesopsn.cw"
 403                                 ,FT_NONE                        ,BASE_NONE              ,NULL
 404                                 ,0                              ,NULL                   ,HFILL }}
 405                 ,{&hf_cw_bits03,{"Bits 0 to 3"                  ,"pwcesopsn.cw.bits03"
 406                                 ,FT_UINT8                       ,BASE_DEC               ,NULL
 407                                 ,0xf0                           ,NULL                   ,HFILL }}
 408                 ,{ &hf_cw_lm,   {"L+M bits"                     ,"pwcesopsn.cw.lm"
 409                                 ,FT_UINT8                       ,BASE_HEX               ,VALS(vals_cw_lm)
 410                                 ,0x0b                           ,NULL                   ,HFILL }}
 411                 ,{&hf_cw_r,     {"R bit: Local CE-bound IWF"    ,"pwcesopsn.cw.rbit"
 412                                 ,FT_UINT8                       ,BASE_DEC               ,VALS(pwc_vals_cw_r_bit)
 413                                 ,0x04                           ,NULL                   ,HFILL }}
 414                 ,{&hf_cw_frg,   {"Fragmentation"                ,"pwcesopsn.cw.frag"
 415                                 ,FT_UINT8                       ,BASE_DEC               ,VALS(pwc_vals_cw_frag)
 416                                 ,0xc0                           ,NULL                   ,HFILL }}
 417                 ,{&hf_cw_len,   {"Length"                       ,"pwcesopsn.cw.length"
 418                                 ,FT_UINT8                       ,BASE_DEC               ,NULL
 419                                 ,0x3f                           ,NULL                   ,HFILL }}
 420                 ,{&hf_cw_seq,   {"Sequence number"              ,"pwcesopsn.cw.seqno"
 421                                 ,FT_UINT16                      ,BASE_DEC               ,NULL
 422                                 ,0                              ,NULL                   ,HFILL }}
 423                 ,{&hf_payload   ,{"TDM payload"                 ,"pwcesopsn.payload"
 424                                 ,FT_BYTES                       ,BASE_NONE              ,NULL
 425                                 ,0                              ,NULL                   ,HFILL }}
 426                 ,{&hf_payload_l ,{"TDM payload length"          ,"pwcesopsn.payload.len"
 427                                 ,FT_INT32                       ,BASE_DEC               ,NULL
 428                                 ,0                              ,NULL                   ,HFILL }}
 429         };
 430
 431         static gint *ett_array[] = {
 432                 &ett
 433         };
 434
 435         proto = proto_register_protocol(pwc_longname_pw_cesopsn, shortname, "pwcesopsn");
 436         proto_register_field_array(proto, hf, array_length(hf));
 437         proto_register_subtree_array(ett_array, array_length(ett_array));
 438         register_dissector("pw_cesopsn_mpls", dissect_pw_cesopsn_mpls, proto);
 439         register_dissector("pw_cesopsn_udp", dissect_pw_cesopsn_udp, proto);
 440         return;
 441 }
 442
 443
 444 void proto_reg_handoff_pw_cesopsn(void)
 445 {
 446         data_handle = find_dissector("data");
 447         pw_padding_handle = find_dissector("pw_padding");
 448         dissector_add_uint("mpls.label", LABEL_INVALID, find_dissector("pw_cesopsn_mpls"));
 449         dissector_add_handle("udp.port", find_dissector("pw_cesopsn_udp")); /* For Decode-As */
 450         return;
 451 }