249 lines
7.7 KiB
C
249 lines
7.7 KiB
C
/* packet-gre.c
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* Routines for the Generic Routing Encapsulation (GRE) protocol
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* Brad Robel-Forrest <brad.robel-forrest@watchguard.com>
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*
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* $Id: packet-gre.c,v 1.4 1999/07/29 05:46:55 gram Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@unicom.net>
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* Copyright 1998 Gerald Combs
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*
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#ifdef HAVE_SYS_TYPES_H
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# include <sys/types.h>
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#endif
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#ifdef HAVE_NETINET_IN_H
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#include <netinet/in.h>
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#endif
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#include <glib.h>
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#include "packet.h"
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static int proto_gre = -1;
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/* bit positions for flags in header */
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#define GH_B_C 0x8000
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#define GH_B_R 0x4000
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#define GH_B_K 0x2000
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#define GH_B_S 0x1000
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#define GH_B_s 0x0800
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#define GH_B_RECUR 0x0700
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#define GH_P_A 0x0080 /* only in special PPTPized GRE header */
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#define GH_P_FLAGS 0x0078 /* only in special PPTPized GRE header */
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#define GH_R_FLAGS 0x00F8
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#define GH_B_VER 0x0007
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#define GRE_PPP 0x880B
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static int calc_len(guint16, int);
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static void add_flags_and_ver(proto_tree *, guint16, int, int);
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void
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dissect_gre(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
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guint16 flags_and_ver = pntohs(pd + offset);
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guint16 type = pntohs(pd + offset + sizeof(flags_and_ver));
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static const value_string typevals[] = {
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{ GRE_PPP, "PPP" },
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{ 0, NULL }
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};
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if (check_col(fd, COL_PROTOCOL))
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col_add_str(fd, COL_PROTOCOL, "GRE");
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if (check_col(fd, COL_INFO)) {
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if (type == GRE_PPP)
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col_add_str(fd, COL_INFO, "Encapsulated PPP");
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else
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col_add_str(fd, COL_INFO, "Encapsulated unknown");
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}
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if (fd->cap_len > offset && tree) {
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int is_ppp;
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proto_item * ti;
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proto_tree * gre_tree;
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if (type == GRE_PPP) {
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is_ppp = 1;
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ti = proto_tree_add_item_format(tree, proto_gre, offset, calc_len(flags_and_ver, 1),
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NULL, "Generic Routing Encapsulation (PPP)");
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gre_tree = proto_item_add_subtree(ti, ETT_GRE);
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add_flags_and_ver(gre_tree, flags_and_ver, offset, 1);
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}
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else {
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is_ppp = 0;
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ti = proto_tree_add_item(tree, proto_gre, offset, calc_len(flags_and_ver, 1), NULL);
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gre_tree = proto_item_add_subtree(ti, ETT_GRE);
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add_flags_and_ver(gre_tree, flags_and_ver, offset, 0);
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}
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offset += sizeof(flags_and_ver);
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proto_tree_add_text(gre_tree, offset, sizeof(type),
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"Protocol Type: %s (%#04x)",
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val_to_str(type, typevals, "Unknown"), type);
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offset += sizeof(type);
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if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) {
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guint16 checksum = pntohs(pd + offset);
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proto_tree_add_text(gre_tree, offset, sizeof(checksum),
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"Checksum: %u", checksum);
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offset += sizeof(checksum);
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}
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if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) {
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guint16 rtoffset = pntohs(pd + offset);
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proto_tree_add_text(gre_tree, offset, sizeof(rtoffset),
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"Offset: %u", rtoffset);
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offset += sizeof(rtoffset);
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}
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if (flags_and_ver & GH_B_K) {
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if (is_ppp) {
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guint16 paylen;
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guint16 callid;
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paylen = pntohs(pd + offset);
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proto_tree_add_text(gre_tree, offset, sizeof(paylen),
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"Payload length: %u", paylen);
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offset += sizeof(paylen);
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callid = pntohs(pd + offset);
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proto_tree_add_text(gre_tree, offset, sizeof(callid),
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"Call ID: %u", callid);
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offset += sizeof(callid);
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}
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else {
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guint32 key = pntohl(pd + offset);
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proto_tree_add_text(gre_tree, offset, sizeof(key),
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"Key: %u", key);
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offset += sizeof(key);
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}
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}
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if (flags_and_ver & GH_B_S) {
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guint32 seqnum = pntohl(pd + offset);
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proto_tree_add_text(gre_tree, offset, sizeof(seqnum),
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"Sequence number: %u", seqnum);
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offset += sizeof(seqnum);
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}
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if (is_ppp && flags_and_ver & GH_P_A) {
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guint32 acknum = pntohl(pd + offset);
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proto_tree_add_text(gre_tree, offset, sizeof(acknum),
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"Acknowledgement number: %u", acknum);
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offset += sizeof(acknum);
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}
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if (flags_and_ver & GH_B_R) {
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proto_tree_add_text(gre_tree, offset, sizeof(guint16),
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"Address family: %u", pntohs(pd + offset));
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offset += sizeof(guint16);
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proto_tree_add_text(gre_tree, offset, 1,
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"SRE offset: %u", pd[offset++]);
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proto_tree_add_text(gre_tree, offset, 1,
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"SRE length: %u", pd[offset++]);
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}
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switch (type) {
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case GRE_PPP:
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dissect_payload_ppp(pd, offset, fd, tree);
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break;
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default:
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dissect_data(pd, offset, fd, gre_tree);
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}
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}
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}
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static int
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calc_len(guint16 flags_and_ver, int is_ppp) {
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int len = 4;
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if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) len += 4;
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if (flags_and_ver & GH_B_K) len += 4;
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if (flags_and_ver & GH_B_S) len += 4;
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if (is_ppp && flags_and_ver & GH_P_A) len += 4;
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return len;
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}
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static void
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add_flags_and_ver(proto_tree *tree, guint16 flags_and_ver, int offset, int is_ppp) {
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proto_item * ti;
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proto_tree * fv_tree;
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int nbits = sizeof(flags_and_ver) * 8;
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ti = proto_tree_add_text(tree, offset, 2,
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"Flags and version: %#08x", flags_and_ver);
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fv_tree = proto_item_add_subtree(ti, ETT_GRE_FLAGS);
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_boolean_bitfield(flags_and_ver, GH_B_C, nbits,
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"Checksum", "No checksum"));
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_boolean_bitfield(flags_and_ver, GH_B_R, nbits,
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"Routing", "No routing"));
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_boolean_bitfield(flags_and_ver, GH_B_K, nbits,
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"Key", "No key"));
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_boolean_bitfield(flags_and_ver, GH_B_S, nbits,
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"Sequence number", "No sequence number"));
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_boolean_bitfield(flags_and_ver, GH_B_s, nbits,
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"Strict source route", "No strict source route"));
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_numeric_bitfield(flags_and_ver, GH_B_RECUR, nbits,
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"Recursion control: %u"));
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if (is_ppp) {
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_boolean_bitfield(flags_and_ver, GH_P_A, nbits,
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"Acknowledgment number", "No acknowledgment number"));
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_numeric_bitfield(flags_and_ver, GH_P_FLAGS, nbits,
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"Flags: %u"));
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}
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else {
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_numeric_bitfield(flags_and_ver, GH_R_FLAGS, nbits,
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"Flags: %u"));
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}
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proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s",
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decode_numeric_bitfield(flags_and_ver, GH_B_VER, nbits,
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"Version: %u"));
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}
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void
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proto_register_gre(void)
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{
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/* static hf_register_info hf[] = {
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{ &variable,
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{ "Name", "gre.abbreviation", TYPE, VALS_POINTER }},
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};*/
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proto_gre = proto_register_protocol("Generic Routing Encapsulation", "gre");
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/* proto_register_field_array(proto_gre, hf, array_length(hf));*/
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}
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