epan/dissectors/packet-gre.c

   1 /* packet-gre.c
   2  * Routines for the Generic Routing Encapsulation (GRE) protocol
   3  * Brad Robel-Forrest <brad.robel-forrest@watchguard.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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  24  */
  25
  26 #include "config.h"
  27
  28 #include <glib.h>
  29 #include <epan/packet.h>
  30 #include <epan/etypes.h>
  31 #include <epan/in_cksum.h>
  32 #include <epan/expert.h>
  33 #include <epan/greproto.h>
  34 #include <epan/ipproto.h>
  35 #include <epan/llcsaps.h>
  36 #include "packet-gre.h"
  37 #include "packet-wccp.h"
  38
  39 /*
  40  * See RFC 1701 "Generic Routing Encapsulation (GRE)", RFC 1702
  41  * "Generic Routing Encapsulation over IPv4 networks", RFC 2637
  42  * "Point-to-Point Tunneling Protocol (PPTP)", RFC 2784 "Generic
  43  * Routing Encapsulation (GRE)", RFC 2890 "Key and Sequence
  44  * Number Extensions to GRE" and draft-ietf-mpls-in-ip-or-gre-07.txt
  45  * "Encapsulating MPLS in IP or Generic Routing Encapsulation (GRE)".
  46  */
  47
  48 static int proto_gre = -1;
  49 static int hf_gre_proto = -1;
  50 static int hf_gre_flags_and_version = -1;
  51 static int hf_gre_flags_checksum = -1;
  52 static int hf_gre_flags_routing = -1;
  53 static int hf_gre_flags_key = -1;
  54 static int hf_gre_flags_sequence_number = -1;
  55 static int hf_gre_flags_strict_source_route = -1;
  56 static int hf_gre_flags_recursion_control = -1;
  57 static int hf_gre_flags_ack = -1;
  58 static int hf_gre_flags_reserved_ppp = -1;
  59 static int hf_gre_flags_reserved = -1;
  60 static int hf_gre_flags_version = -1;
  61 static int hf_gre_checksum = -1;
  62 static int hf_gre_offset = -1;
  63 static int hf_gre_key = -1;
  64 static int hf_gre_key_payload_length = -1;
  65 static int hf_gre_key_call_id = -1;
  66 static int hf_gre_sequence_number = -1;
  67 static int hf_gre_ack_number = -1;
  68 static int hf_gre_routing = -1;
  69 static int hf_gre_routing_address_family = -1;
  70 static int hf_gre_routing_sre_length = -1;
  71 static int hf_gre_routing_sre_offset = -1;
  72 static int hf_gre_routing_information = -1;
  73
  74 /* Ref 3GPP2 A.S0012-C v2.0 and A.S0008-A v1.0 */
  75 static int hf_gre_3ggp2_attrib = -1;
  76 static int hf_gre_3ggp2_attrib_id = -1;
  77 static int hf_gre_3ggp2_attrib_length = -1;
  78 static int hf_gre_3ggp2_sdi = -1;
  79 static int hf_gre_3ggp2_fci = -1;
  80 static int hf_gre_3ggp2_di = -1;
  81 static int hf_gre_3ggp2_flow_disc = -1;
  82 static int hf_gre_3ggp2_seg = -1;
  83
  84 static int hf_gre_wccp_redirect_header = -1;
  85 static int hf_gre_wccp_dynamic_service = -1;
  86 static int hf_gre_wccp_alternative_bucket_used = -1;
  87 static int hf_gre_wccp_redirect_header_valid = -1;
  88 static int hf_gre_wccp_service_id = -1;
  89 static int hf_gre_wccp_alternative_bucket = -1;
  90 static int hf_gre_wccp_primary_bucket = -1;
  91
  92 static gint ett_gre = -1;
  93 static gint ett_gre_flags = -1;
  94 static gint ett_gre_routing = -1;
  95 static gint ett_gre_wccp2_redirect_header = -1;
  96 static gint ett_3gpp2_attribs = -1;
  97 static gint ett_3gpp2_attr = -1;
  98
  99 static expert_field ei_gre_checksum_incorrect = EI_INIT;
 100
 101 static dissector_table_t gre_dissector_table;
 102 static dissector_handle_t data_handle;
 103
 104 /* bit positions for flags in header */
 105 #define GRE_CHECKSUM            0x8000
 106 #define GRE_ROUTING             0x4000
 107 #define GRE_KEY                 0x2000
 108 #define GRE_SEQUENCE            0x1000
 109 #define GRE_STRICTSOURCE        0x0800
 110 #define GRE_RECURSION           0x0700
 111 #define GRE_ACK                 0x0080  /* only in special PPTPized GRE header */
 112 #define GRE_RESERVED_PPP        0x0078  /* only in special PPTPized GRE header */
 113 #define GRE_RESERVED            0x00F8
 114 #define GRE_VERSION             0x0007
 115
 116
 117 const value_string gre_version[] = {
 118     { 0, "GRE" },                /* [RFC2784] */
 119     { 1, "Enhanced GRE" },       /* [RFC2637] */
 120     { 0, NULL}
 121 };
 122 const value_string gre_typevals[] = {
 123     { GRE_KEEPALIVE,       "Possible GRE keepalive packet" },
 124     { ETHERTYPE_PPP,       "PPP" },
 125     { ETHERTYPE_IP,        "IP" },
 126     { SAP_OSINL5,          "OSI"},
 127     { GRE_WCCP,            "WCCP"},
 128     { GRE_NHRP,            "NHRP"},
 129     { GRE_ERSPAN_88BE,     "ERSPAN"},
 130     { GRE_ERSPAN_22EB,     "ERSPAN"},
 131     { ETHERTYPE_IPX,       "IPX"},
 132     { ETHERTYPE_ETHBRIDGE, "Transparent Ethernet bridging" },
 133     { ETHERTYPE_RAW_FR,    "Frame Relay"},
 134     { ETHERTYPE_IPv6,      "IPv6" },
 135     { ETHERTYPE_MPLS,      "MPLS label switched packet" },
 136     { ETHERTYPE_CDMA2000_A10_UBS,"CDMA2000 A10 Unstructured byte stream" },
 137     { ETHERTYPE_3GPP2,     "CDMA2000 A10 3GPP2 Packet" },
 138     { GRE_ARUBA_8200,      "ARUBA WLAN" },
 139     { GRE_ARUBA_8210,      "ARUBA WLAN" },
 140     { GRE_ARUBA_8220,      "ARUBA WLAN" },
 141     { GRE_ARUBA_8230,      "ARUBA WLAN" },
 142     { GRE_ARUBA_8240,      "ARUBA WLAN" },
 143     { GRE_ARUBA_8250,      "ARUBA WLAN" },
 144     { GRE_ARUBA_8260,      "ARUBA WLAN" },
 145     { GRE_ARUBA_8270,      "ARUBA WLAN" },
 146     { GRE_ARUBA_8280,      "ARUBA WLAN" },
 147     { GRE_ARUBA_8290,      "ARUBA WLAN" },
 148     { GRE_ARUBA_82A0,      "ARUBA WLAN" },
 149     { GRE_ARUBA_82B0,      "ARUBA WLAN" },
 150     { GRE_ARUBA_82C0,      "ARUBA WLAN" },
 151     { GRE_ARUBA_82D0,      "ARUBA WLAN" },
 152     { GRE_ARUBA_82E0,      "ARUBA WLAN" },
 153     { GRE_ARUBA_82F0,      "ARUBA WLAN" },
 154     { GRE_ARUBA_8300,      "ARUBA WLAN" },
 155     { GRE_ARUBA_8310,      "ARUBA WLAN" },
 156     { GRE_ARUBA_8320,      "ARUBA WLAN" },
 157     { GRE_ARUBA_8330,      "ARUBA WLAN" },
 158     { GRE_ARUBA_8340,      "ARUBA WLAN" },
 159     { GRE_ARUBA_8350,      "ARUBA WLAN" },
 160     { GRE_ARUBA_8360,      "ARUBA WLAN" },
 161     { GRE_ARUBA_8370,      "ARUBA WLAN" },
 162     { GRE_ARUBA_9000,      "ARUBA WLAN" },
 163     { 0,                   NULL }
 164 };
 165
 166 #define ID_3GPP2_SDI_FLAG 1
 167 #define ID_3GPP2_FLOW_CTRL 2
 168 #define ID_3GPP2_FLOW_DISCRIMINATOR 3
 169 #define ID_3GPP2_SEG 4
 170
 171 static const value_string gre_3ggp2_seg_vals[] = {
 172     { 0x00, "Packet Started" },
 173     { 0x01, "Packet continued" },
 174     { 0x02, "Packet Ended" },
 175     { 0,    NULL }
 176 };
 177 /* 3GPP2 A.S0012-C v2.0
 178  * 2.6.1 GRE Attributes
 179  */
 180 static const value_string gre_3ggp2_attrib_id_vals[] = {
 181     { 0x01, "1x SDB/HRPD DOS Indicator" },
 182     { 0x02, "Flow Control Indication" },
 183     /* A.S0008-A v1.0 */
 184     { 0x03, "IP Flow Discriminator" },
 185     { 0x04, "Segmentation Indication" },
 186     { 0,    NULL }
 187 };
 188
 189 static const true_false_string gre_3ggp2_sdi_val = {
 190     "Packet suitable for 1x SDB or HRPD DOS transmission",
 191     "Reserved"
 192 };
 193
 194 static const true_false_string gre_3ggp2_fci_val = {
 195     "XOFF",
 196     "XON"
 197 };
 198
 199 static const true_false_string gre_3ggp2_di_val = {
 200     "INDEFINITE:",
 201     "TEMPORARY"
 202 };
 203
 204 static const true_false_string gre_wccp_dynamic_service_val = {
 205     "Dynamic service",
 206     "Well-known service"
 207 };
 208
 209 static const true_false_string gre_wccp_alternative_bucket_used_val = {
 210     "Alternative bucket used",
 211     "Primary bucket used",
 212 };
 213
 214 static const true_false_string gre_wccp_redirect_header_valid_val = {
 215   "Header is present, but ignore contents",
 216   "Header contents are valid",
 217 };
 218
 219
 220 static int
 221 dissect_gre_3gpp2_attribs(tvbuff_t *tvb, int offset, proto_tree *tree)
 222 {
 223     gboolean    last_attrib  = FALSE;
 224     proto_item *attr_item;
 225     proto_tree *attr_tree;
 226     guint8      value;
 227     int         start_offset = offset;
 228
 229     proto_item *ti = proto_tree_add_item(tree, hf_gre_3ggp2_attrib, tvb, offset, 0, ENC_NA);
 230     proto_tree *atree = proto_item_add_subtree(ti, ett_3gpp2_attribs);
 231
 232     while(last_attrib != TRUE)
 233     {
 234         guint8 attrib_id = tvb_get_guint8(tvb, offset);
 235         guint8 attrib_length = tvb_get_guint8(tvb, offset + 1);
 236
 237         attr_item = proto_tree_add_text(atree, tvb, offset, attrib_length + 1 + 1, "%s",
 238                                         val_to_str((attrib_id&0x7f), gre_3ggp2_attrib_id_vals, "%u (Unknown)"));
 239         attr_tree = proto_item_add_subtree(attr_item, ett_3gpp2_attr);
 240
 241         proto_tree_add_item(attr_tree, hf_gre_3ggp2_attrib_id, tvb, offset, 1, ENC_BIG_ENDIAN);
 242         proto_tree_add_item(attr_tree, hf_gre_3ggp2_attrib_length, tvb, offset+1, 1, ENC_BIG_ENDIAN);
 243
 244         offset += 2;
 245         last_attrib = (attrib_id & 0x80)?TRUE:FALSE;
 246         attrib_id &= 0x7F;
 247
 248         switch(attrib_id)
 249         {
 250         case ID_3GPP2_FLOW_DISCRIMINATOR:
 251         {
 252             value = tvb_get_guint8(tvb,offset);
 253             proto_tree_add_item(attr_tree, hf_gre_3ggp2_flow_disc, tvb, offset, attrib_length, ENC_NA);
 254             proto_item_append_text(attr_item," - 0x%x",value);
 255         }
 256         break;
 257         case ID_3GPP2_SDI_FLAG:
 258         {
 259             value = tvb_get_guint8(tvb,offset);
 260             proto_tree_add_item(attr_tree, hf_gre_3ggp2_sdi, tvb, offset, attrib_length, ENC_BIG_ENDIAN);
 261             proto_item_append_text(attr_item," - %s",
 262                                    (value & 0x80) ? "Packet suitable for 1x SDB or HRPD DOS transmission" : "Reserved");
 263
 264         }
 265         break;
 266         case ID_3GPP2_SEG:
 267         {
 268             value = tvb_get_guint8(tvb,offset) >>6;
 269             proto_tree_add_item(attr_tree, hf_gre_3ggp2_seg, tvb, offset, attrib_length, ENC_BIG_ENDIAN);
 270             proto_item_append_text(attr_item," - %s",val_to_str(value, gre_3ggp2_seg_vals, "0x%02X - Unknown"));
 271         }
 272         break;
 273         case ID_3GPP2_FLOW_CTRL:
 274         {
 275             value = tvb_get_guint8(tvb,offset);
 276             proto_tree_add_item(attr_tree, hf_gre_3ggp2_fci, tvb, offset, attrib_length, ENC_BIG_ENDIAN);
 277             proto_item_append_text(attr_item," - %s",
 278                                    (value & 0x80) ? "XON" : "XOFF");
 279             proto_tree_add_item(attr_tree, hf_gre_3ggp2_di, tvb, offset, attrib_length, ENC_BIG_ENDIAN);
 280             proto_item_append_text(attr_item,"/%s",
 281                                    (value & 0x40) ? "INDEFINITE" : "TEMPORARY");
 282         }
 283         break;
 284         }
 285
 286         offset += attrib_length;
 287     }
 288     proto_item_set_len(ti, offset - start_offset);
 289
 290     return offset;
 291 }
 292
 293 static void
 294 dissect_gre_wccp2_redirect_header(tvbuff_t *tvb, int offset, proto_tree *tree)
 295 {
 296     proto_item *ti;
 297     proto_tree *rh_tree;
 298
 299     ti = proto_tree_add_item(tree, hf_gre_wccp_redirect_header, tvb, offset, 4, ENC_NA);
 300     rh_tree = proto_item_add_subtree(ti, ett_gre_wccp2_redirect_header);
 301
 302     proto_tree_add_item(rh_tree, hf_gre_wccp_dynamic_service, tvb, offset, 1, ENC_BIG_ENDIAN);
 303
 304     proto_tree_add_item(rh_tree, hf_gre_wccp_alternative_bucket_used, tvb, offset, 1, ENC_BIG_ENDIAN);
 305
 306     proto_tree_add_item(rh_tree, hf_gre_wccp_redirect_header_valid, tvb, offset, 1, FALSE);
 307
 308     proto_tree_add_item(rh_tree, hf_gre_wccp_service_id, tvb, offset +1, 1, ENC_BIG_ENDIAN);
 309
 310     proto_tree_add_item(rh_tree, hf_gre_wccp_alternative_bucket, tvb, offset +2, 1, ENC_BIG_ENDIAN);
 311
 312     proto_tree_add_item(rh_tree, hf_gre_wccp_primary_bucket, tvb, offset +3, 1, ENC_BIG_ENDIAN);
 313 }
 314
 315 static void
 316 dissect_gre(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 317 {
 318
 319     int         offset             = 0;
 320     guint16     flags_and_ver;
 321     guint16     type;
 322     gboolean    is_ppp             = FALSE;
 323     gboolean    is_wccp2           = FALSE;
 324     proto_item *ti, *it_flags;
 325     proto_tree *gre_tree, *fv_tree = NULL;
 326     guint16     sre_af;
 327     guint8      sre_length;
 328     tvbuff_t   *next_tvb;
 329
 330     flags_and_ver = tvb_get_ntohs(tvb, offset);
 331     type = tvb_get_ntohs(tvb, offset + 2);
 332
 333     col_set_str(pinfo->cinfo, COL_PROTOCOL, "GRE");
 334
 335     col_add_fstr(pinfo->cinfo, COL_INFO, "Encapsulated %s", val_to_str(type, gre_typevals, "0x%04X (unknown)"));
 336
 337     switch (type) {
 338
 339     case ETHERTYPE_PPP:
 340         if (flags_and_ver & GRE_ACK)
 341             is_ppp = TRUE;
 342         break;
 343     case ETHERTYPE_3GPP2:
 344     case ETHERTYPE_CDMA2000_A10_UBS:
 345         is_ppp = TRUE;
 346         break;
 347
 348     case GRE_WCCP:
 349         /* WCCP2 puts an extra 4 octets into the header, but uses the same
 350            encapsulation type; if it looks as if the first octet of the packet
 351            isn't the beginning of an IPv4 header, assume it's WCCP2. */
 352         if ((tvb_get_guint8(tvb, offset + 2 + 2) & 0xF0) != 0x40) {
 353             is_wccp2 = TRUE;
 354         }
 355         break;
 356     }
 357
 358     /* Per README.developer, section 1.2, we must call subdissectors regardless
 359      * of whether "tree" is NULL or not.  That is done below using
 360      * call_dissector(), but since the next_tvb must begin at the correct offset,
 361      * it's easier and more readable to always enter this block in order to
 362      * compute the correct offset to pass to tvb_new_subset_remaining().
 363      */
 364     if (1) {
 365         ti = proto_tree_add_protocol_format(tree, proto_gre, tvb, offset, -1, "Generic Routing Encapsulation (%s)",
 366                                             val_to_str(type, gre_typevals, "0x%04X - unknown"));
 367         gre_tree = proto_item_add_subtree(ti, ett_gre);
 368
 369
 370         it_flags = proto_tree_add_item(gre_tree, hf_gre_flags_and_version, tvb, offset, 2, ENC_BIG_ENDIAN);
 371         fv_tree = proto_item_add_subtree(it_flags, ett_gre_flags);
 372
 373         proto_tree_add_item(fv_tree, hf_gre_flags_checksum, tvb, offset, 2, ENC_BIG_ENDIAN);
 374
 375         proto_tree_add_item(fv_tree, hf_gre_flags_routing, tvb, offset, 2, ENC_BIG_ENDIAN);
 376
 377         proto_tree_add_item(fv_tree, hf_gre_flags_key, tvb, offset, 2, ENC_BIG_ENDIAN);
 378
 379         proto_tree_add_item(fv_tree, hf_gre_flags_sequence_number, tvb, offset, 2, ENC_BIG_ENDIAN);
 380
 381         proto_tree_add_item(fv_tree, hf_gre_flags_strict_source_route, tvb, offset, 2, ENC_BIG_ENDIAN);
 382
 383         proto_tree_add_item(fv_tree, hf_gre_flags_recursion_control, tvb, offset, 2, ENC_BIG_ENDIAN);
 384
 385         /* RFC2637 Section 4.1 : Enhanced GRE Header */
 386         if (is_ppp) {
 387             proto_tree_add_item(fv_tree, hf_gre_flags_ack, tvb, offset, 2, ENC_BIG_ENDIAN);
 388
 389             proto_tree_add_item(fv_tree, hf_gre_flags_reserved_ppp, tvb, offset, 2, ENC_BIG_ENDIAN);
 390         }
 391         else {
 392             proto_tree_add_item(fv_tree, hf_gre_flags_reserved, tvb, offset, 2, ENC_BIG_ENDIAN);
 393         }
 394
 395         proto_tree_add_item(fv_tree, hf_gre_flags_version, tvb, offset, 2, ENC_BIG_ENDIAN);
 396
 397         offset += 2;
 398
 399         proto_tree_add_item(gre_tree, hf_gre_proto, tvb, offset, 2, ENC_BIG_ENDIAN);
 400         offset += 2;
 401
 402         if (flags_and_ver & GRE_CHECKSUM || flags_and_ver & GRE_ROUTING) {
 403             guint length, reported_length;
 404             proto_item *it_checksum;
 405             vec_t cksum_vec[1];
 406             guint16 cksum, computed_cksum;
 407
 408             it_checksum = proto_tree_add_item(gre_tree, hf_gre_checksum, tvb, offset, 2, ENC_BIG_ENDIAN);
 409             /* Checksum check !... */
 410             cksum = tvb_get_ntohs(tvb, offset);
 411             length = tvb_length(tvb);
 412             reported_length = tvb_reported_length(tvb);
 413             /* The Checksum Present bit is set, and the packet isn't part of a
 414                fragmented datagram and isn't truncated, so we can checksum it. */
 415             if ((flags_and_ver & GRE_CHECKSUM) && !pinfo->fragmented && length >= reported_length) {
 416                 cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, reported_length);
 417                 cksum_vec[0].len = reported_length;
 418                 computed_cksum = in_cksum(cksum_vec, 1);
 419                 if (computed_cksum == 0) {
 420                     proto_item_append_text(it_checksum," [correct]");
 421                 } else {
 422                     proto_item_append_text(it_checksum," [incorrect, should be 0x%04x]",in_cksum_shouldbe(cksum, computed_cksum));
 423                     expert_add_info(pinfo, it_checksum, &ei_gre_checksum_incorrect);
 424                 }
 425             }
 426
 427
 428             offset += 2;
 429
 430             proto_tree_add_item(gre_tree, hf_gre_offset, tvb, offset, 2, ENC_BIG_ENDIAN);
 431             offset += 2;
 432         }
 433
 434         if (flags_and_ver & GRE_KEY) {
 435             /* RFC2637 Section 4.1 : Enhanced GRE Header */
 436             if (is_ppp && type!=ETHERTYPE_CDMA2000_A10_UBS) {
 437
 438                 proto_tree_add_item(gre_tree, hf_gre_key_payload_length, tvb, offset, 2, ENC_BIG_ENDIAN);
 439                 offset += 2;
 440
 441                 proto_tree_add_item(gre_tree, hf_gre_key_call_id, tvb, offset, 2, ENC_BIG_ENDIAN);
 442                 offset += 2;
 443             }
 444             else {
 445                 proto_tree_add_item(gre_tree, hf_gre_key, tvb, offset, 4, ENC_BIG_ENDIAN);
 446                 offset += 4;
 447             }
 448         }
 449         if (flags_and_ver & GRE_SEQUENCE) {
 450
 451             proto_tree_add_item(gre_tree, hf_gre_sequence_number , tvb, offset, 4, ENC_BIG_ENDIAN);
 452             offset += 4;
 453         }
 454         if (is_ppp && (flags_and_ver & GRE_ACK)) {
 455
 456             proto_tree_add_item(gre_tree, hf_gre_ack_number , tvb, offset, 4, ENC_BIG_ENDIAN);
 457             offset += 4;
 458         }
 459         if (flags_and_ver & GRE_ROUTING) {
 460             proto_item *it_routing;
 461             proto_tree *r_tree;
 462             for (;;) {
 463
 464                 it_routing = proto_tree_add_item(gre_tree, hf_gre_routing, tvb, offset, -1, ENC_NA);
 465                 r_tree = proto_item_add_subtree(ti, ett_gre_routing);
 466
 467                 sre_af = tvb_get_ntohs(tvb, offset);
 468                 proto_tree_add_item(r_tree, hf_gre_routing_address_family , tvb, offset, 2, ENC_BIG_ENDIAN);
 469                 offset += 2;
 470
 471                 proto_tree_add_item(r_tree, hf_gre_routing_sre_offset , tvb, offset, 1, ENC_BIG_ENDIAN);
 472                 offset += 1;
 473
 474                 sre_length = tvb_get_guint8(tvb, offset);
 475                 proto_tree_add_item(r_tree, hf_gre_routing_sre_length , tvb, offset, 1, ENC_BIG_ENDIAN);
 476                 offset += 1;
 477
 478                 proto_item_set_len(it_routing, 2 + 1 +1 + sre_length);
 479                 if (sre_af == 0 && sre_length == 0)
 480                     break;
 481
 482                 proto_tree_add_item(r_tree, hf_gre_routing_information , tvb, offset, sre_length, ENC_NA);
 483                 offset += sre_length;
 484             }
 485         }
 486
 487         if (type == GRE_WCCP && is_wccp2) {
 488             dissect_gre_wccp2_redirect_header(tvb, offset, gre_tree);
 489             offset += 4;
 490         }
 491         if (type == ETHERTYPE_3GPP2) {
 492             offset = dissect_gre_3gpp2_attribs(tvb, offset, gre_tree);
 493         }
 494
 495         proto_item_set_len(ti, offset);
 496
 497         /* If the S bit is not set, this packet might not have a payload, so
 498            check whether there's any data left, first.
 499
 500            XXX - the S bit isn't in RFC 2784, which deprecates that bit
 501            and some other bits in RFC 1701 and says that they should be
 502            zero for RFC 2784-compliant GRE; as such, the absence of the
 503            S bit doesn't necessarily mean there's no payload.  */
 504         if (!(flags_and_ver & GRE_SEQUENCE)) {
 505             if (tvb_reported_length_remaining(tvb, offset) <= 0)
 506                 return; /* no payload */
 507         }
 508         next_tvb = tvb_new_subset_remaining(tvb, offset);
 509         pinfo->flags.in_gre_pkt = TRUE;
 510         if (!dissector_try_uint(gre_dissector_table, type, next_tvb, pinfo, tree))
 511             call_dissector(data_handle,next_tvb, pinfo, gre_tree);
 512     }
 513 }
 514
 515
 516 void
 517 proto_register_gre(void)
 518 {
 519     static hf_register_info hf[] = {
 520         { &hf_gre_proto,
 521           { "Protocol Type", "gre.proto",
 522             FT_UINT16, BASE_HEX, VALS(gre_typevals), 0x0,
 523             "The protocol that is GRE encapsulated", HFILL }
 524         },
 525         { &hf_gre_flags_and_version,
 526           { "Flags and Version", "gre.flags_and_version",
 527             FT_UINT16, BASE_HEX, NULL, 0x0,
 528             "The GRE flags are encoded in the first two octets", HFILL }
 529         },
 530         { &hf_gre_flags_checksum,
 531           { "Checksum Bit", "gre.flags.checksum",
 532             FT_BOOLEAN, 16, TFS(&tfs_yes_no), GRE_CHECKSUM,
 533             "Indicates if the Checksum field is present", HFILL }
 534         },
 535         { &hf_gre_flags_routing,
 536           { "Routing Bit", "gre.flags.routing",
 537             FT_BOOLEAN, 16, TFS(&tfs_yes_no), GRE_ROUTING,
 538             "Indicates if the Routing and Checksum/Offset field are present", HFILL }
 539         },
 540         { &hf_gre_flags_key,
 541           { "Key Bit", "gre.flags.key",
 542             FT_BOOLEAN, 16, TFS(&tfs_yes_no), GRE_KEY,
 543             "Indicates if the Key field is present", HFILL }
 544         },
 545         { &hf_gre_flags_sequence_number,
 546           { "Sequence Number Bit", "gre.flags.sequence_number",
 547             FT_BOOLEAN, 16, TFS(&tfs_yes_no), GRE_SEQUENCE,
 548             "Indicates if the Sequence Number field is present", HFILL }
 549         },
 550         { &hf_gre_flags_strict_source_route,
 551           { "Strict Source Route Bit", "gre.flags.strict_source_route",
 552             FT_BOOLEAN, 16, TFS(&tfs_yes_no), GRE_STRICTSOURCE,
 553             NULL, HFILL }
 554         },
 555         { &hf_gre_flags_recursion_control,
 556           { "Recursion control", "gre.flags.recursion_control",
 557             FT_UINT16, BASE_DEC, NULL, GRE_RECURSION,
 558             NULL, HFILL }
 559         },
 560         { &hf_gre_flags_ack,
 561           { "Acknowledgment", "gre.flags.ack",
 562             FT_BOOLEAN, 16, TFS(&tfs_yes_no), GRE_ACK,
 563             "Indicates if the packet packet contains Acknowledgment Number to be used for acknowledging previously transmitted data", HFILL }
 564         },
 565         { &hf_gre_flags_reserved,
 566           { "Flags (Reserved)", "gre.flags.reserved",
 567             FT_UINT16, BASE_DEC, NULL, GRE_RESERVED,
 568             NULL, HFILL }
 569         },
 570         { &hf_gre_flags_reserved_ppp,
 571           { "Flags (Reserved)", "gre.flags.reserved",
 572             FT_UINT16, BASE_DEC, NULL, GRE_RESERVED_PPP,
 573             NULL, HFILL }
 574         },
 575         { &hf_gre_flags_version,
 576           { "Version", "gre.flags.version",
 577             FT_UINT16, BASE_DEC, VALS(gre_version), GRE_VERSION,
 578             NULL, HFILL }
 579         },
 580         { &hf_gre_checksum,
 581           { "Checksum", "gre.checksum",
 582             FT_UINT16, BASE_HEX, NULL, 0x0,
 583             "The Checksum field contains the IP (one's complement) checksum of the GRE header and the payload packet", HFILL }
 584         },
 585         { &hf_gre_offset,
 586           { "Offset", "gre.offset",
 587             FT_UINT16, BASE_DEC, NULL, 0x0,
 588             "The offset field indicates the octet offset from the start of the Routing field to the first octet of the active Source Route Entry to be examined", HFILL }
 589         },
 590         { &hf_gre_key,
 591           { "Key", "gre.key",
 592             FT_UINT32, BASE_HEX, NULL, 0x0,
 593             "The Key field contains a four octet number which was inserted by the encapsulator", HFILL }
 594         },
 595         { &hf_gre_key_payload_length,
 596           { "Payload Length", "gre.key.payload_length",
 597             FT_UINT16, BASE_DEC, NULL, 0x0,
 598             "Size of the payload, not including the GRE header", HFILL }
 599         },
 600         { &hf_gre_key_call_id,
 601           { "Call ID", "gre.key.call_id",
 602             FT_UINT16, BASE_DEC, NULL, 0x0,
 603             "Contains the Peer's Call ID for the session to which this packet belongs.", HFILL }
 604         },
 605         { &hf_gre_sequence_number,
 606           { "Sequence Number", "gre.sequence_number",
 607             FT_UINT32, BASE_DEC, NULL, 0x0,
 608             "The Sequence Number field contains an unsigned 32 bit integer which is inserted by the encapsulator", HFILL }
 609         },
 610         { &hf_gre_ack_number,
 611           { "Acknowledgment Number", "gre.ack_number",
 612             FT_UINT32, BASE_DEC, NULL, 0x0,
 613             "Contains the sequence number of the highest numbered GRE packet received by the sending peer for this user session", HFILL }
 614         },
 615         { &hf_gre_routing,
 616           { "Routing", "gre.routing",
 617             FT_NONE, BASE_NONE, NULL, 0x0,
 618             "The Routing field is a list of Source Route Entries (SREs)", HFILL }
 619         },
 620         { &hf_gre_routing_address_family,
 621           { "Address Family", "gre.routing.address_family",
 622             FT_UINT16, BASE_DEC, NULL, 0x0,
 623             "The Address Family field contains a two octet value which indicates the syntax and semantics of the Routing Information field", HFILL }
 624         },
 625         { &hf_gre_routing_sre_offset,
 626           { "SRE Offset", "gre.routing.sre_offset",
 627             FT_UINT8, BASE_DEC, NULL, 0x0,
 628             "The Address Family field contains a two octet value which indicates the syntax and semantics of the Routing Information field", HFILL }
 629         },
 630         { &hf_gre_routing_sre_length,
 631           { "SRE Length", "gre.routing.src_length",
 632             FT_UINT8, BASE_DEC, NULL, 0x0,
 633             "The SRE Length field contains the number of octets in the SRE", HFILL }
 634         },
 635         { &hf_gre_routing_information,
 636           { "Routing Information", "gre.routing.information",
 637             FT_BYTES, BASE_NONE, NULL, 0x0,
 638             "The Routing Information field contains data which may be used in routing this packet", HFILL }
 639         },
 640         { &hf_gre_3ggp2_attrib,
 641           { "3GGP2 Attributes", "gre.ggp2_attrib",
 642             FT_NONE, BASE_NONE, NULL, 0x0,
 643             NULL, HFILL }
 644         },
 645         { &hf_gre_3ggp2_attrib_id,
 646           { "Type", "gre.ggp2_attrib_id",
 647             FT_UINT8, BASE_HEX, VALS(gre_3ggp2_attrib_id_vals), 0x7f,
 648             NULL, HFILL }
 649         },
 650         { &hf_gre_3ggp2_attrib_length,
 651           { "Length", "gre.ggp2_attrib_length",
 652             FT_UINT8, BASE_HEX, NULL, 0x0,
 653             NULL, HFILL }
 654         },
 655         { &hf_gre_3ggp2_sdi,
 656           { "SDI/DOS", "gre.3ggp2_sdi",
 657             FT_BOOLEAN, 16, TFS(&gre_3ggp2_sdi_val), 0x8000,
 658             "Short Data Indicator(SDI)/Data Over Signaling (DOS)", HFILL }
 659         },
 660         { &hf_gre_3ggp2_fci,
 661           { "Flow Control Indicator", "gre.3ggp2_fci",
 662             FT_BOOLEAN, 16, TFS(&gre_3ggp2_fci_val), 0x8000,
 663             NULL, HFILL }
 664         },
 665         { &hf_gre_3ggp2_di,
 666           { "Duration Indicator", "gre.3ggp2_di",
 667             FT_BOOLEAN, 16, TFS(&gre_3ggp2_di_val), 0x4000,
 668             NULL, HFILL }
 669         },
 670         { &hf_gre_3ggp2_flow_disc,
 671           { "Flow ID", "gre.ggp2_flow_disc",
 672             FT_BYTES, BASE_NONE, NULL, 0x0,
 673             NULL, HFILL }
 674         },
 675         { &hf_gre_3ggp2_seg,
 676           { "Type", "gre.ggp2_3ggp2_seg",
 677             FT_UINT16, BASE_HEX, VALS(gre_3ggp2_seg_vals), 0xc000,
 678             NULL, HFILL }
 679         },
 680
 681         { &hf_gre_wccp_redirect_header,
 682           { "Redirect Header", "gre.wccp.redirect_header",
 683             FT_NONE, BASE_NONE, NULL, 0x0,
 684             NULL, HFILL }
 685         },
 686         { &hf_gre_wccp_dynamic_service,
 687           { "Dynamic Service", "gre.wccp.dynamic_service",
 688             FT_BOOLEAN, 8, TFS(&gre_wccp_dynamic_service_val), 0x01,
 689             NULL, HFILL }
 690         },
 691         { &hf_gre_wccp_alternative_bucket_used,
 692           { "Alternative bucket used", "gre.wccp.alternative_bucket_used",
 693             FT_BOOLEAN, 8, TFS(&gre_wccp_alternative_bucket_used_val), 0x02,
 694             NULL, HFILL }
 695         },
 696         { &hf_gre_wccp_redirect_header_valid,
 697           { "WCCP Redirect header is valid", "gre.wccp.redirect_header_valid",
 698             FT_BOOLEAN, 8, TFS(&gre_wccp_redirect_header_valid_val), 0x04,
 699             NULL, HFILL }
 700         },
 701         { &hf_gre_wccp_service_id,
 702           { "Service ID", "gre.wccp.service_id",
 703             FT_UINT8, BASE_DEC, VALS(service_id_vals), 0x00,
 704             "Service Group identifier", HFILL }
 705         },
 706         { &hf_gre_wccp_alternative_bucket,
 707           { "Alternative Bucket", "gre.wccp.alternative_bucket",
 708             FT_UINT8, BASE_DEC, NULL, 0x0,
 709             "Alternative bucket index used to redirect the packet.", HFILL }
 710         },
 711         { &hf_gre_wccp_primary_bucket,
 712           { "Primary Bucket", "gre.wccp.primary_bucket",
 713             FT_UINT8, BASE_DEC, NULL, 0x0,
 714             "Primary bucket index used to redirect the packet.", HFILL  }
 715         },
 716     };
 717     static gint *ett[] = {
 718         &ett_gre,
 719         &ett_gre_flags,
 720         &ett_gre_routing,
 721         &ett_gre_wccp2_redirect_header,
 722         &ett_3gpp2_attribs,
 723         &ett_3gpp2_attr,
 724     };
 725
 726
 727     static ei_register_info ei[] = {
 728         { &ei_gre_checksum_incorrect, { "gre.checksum.incorrect", PI_PROTOCOL, PI_WARN, "Incorrect GRE Checksum", EXPFILL }},
 729     };
 730
 731     expert_module_t* expert_gre;
 732
 733     proto_gre = proto_register_protocol("Generic Routing Encapsulation",
 734                                         "GRE", "gre");
 735     proto_register_field_array(proto_gre, hf, array_length(hf));
 736     proto_register_subtree_array(ett, array_length(ett));
 737     expert_gre = expert_register_protocol(proto_gre);
 738     expert_register_field_array(expert_gre, ei, array_length(ei));
 739
 740     /* subdissector code */
 741     gre_dissector_table = register_dissector_table("gre.proto",
 742                                                    "GRE protocol type", FT_UINT16, BASE_HEX);
 743 }
 744
 745 void
 746 proto_reg_handoff_gre(void)
 747 {
 748     dissector_handle_t gre_handle;
 749
 750     gre_handle = create_dissector_handle(dissect_gre, proto_gre);
 751     dissector_add_uint("ip.proto", IP_PROTO_GRE, gre_handle);
 752     data_handle = find_dissector("data");
 753 }