forked from osmocom/wireshark
304 lines
9.2 KiB
C
304 lines
9.2 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 1.22 2000/05/31 05:07:05 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@zing.org>
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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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#include "packet-ip.h"
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#include "packet-ppp.h"
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#include "packet-ipx.h"
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static int proto_gre = -1;
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static int hf_gre_proto = -1;
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static gint ett_gre = -1;
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static gint ett_gre_flags = -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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#define GRE_IP 0x0800
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#define GRE_WCCP 0x883E
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#define GRE_IPX 0x8137
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static void add_flags_and_ver(proto_tree *, guint16, int, int);
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static const value_string typevals[] = {
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{ GRE_PPP, "PPP" },
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{ GRE_IP, "IP" },
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{ GRE_WCCP, "WCCP"},
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{ GRE_IPX, "IPX"},
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{ 0, NULL }
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};
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static 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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guint16 sre_af;
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guint8 sre_length;
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tvbuff_t *next_tvb;
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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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col_add_fstr(fd, COL_INFO, "Encapsulated %s",
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val_to_str(type, typevals, "0x%04X (unknown)"));
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}
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if (IS_DATA_IN_FRAME(offset) && tree) {
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gboolean is_ppp = FALSE;
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gboolean is_wccp2 = FALSE;
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proto_item * ti;
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proto_tree * gre_tree;
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guint len = 4;
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if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R)
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len += 4;
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if (flags_and_ver & GH_B_K)
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len += 4;
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if (flags_and_ver & GH_B_S)
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len += 4;
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switch (type) {
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case GRE_PPP:
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if (flags_and_ver & GH_P_A)
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len += 4;
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is_ppp = TRUE;
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break;
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case GRE_WCCP:
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/* WCCP2 apparently puts an extra 4 octets into the header, but uses
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the same encapsulation type; if it looks as if the first octet of
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the packet isn't the beginning of an IPv4 header, assume it's
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WCCP2. */
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if ((pd[offset + sizeof(flags_and_ver) + sizeof(type)] & 0xF0) != 0x40) {
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len += 4;
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is_wccp2 = TRUE;
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}
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break;
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}
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ti = proto_tree_add_protocol_format(tree, proto_gre, NullTVB, offset, len,
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"Generic Routing Encapsulation (%s)",
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val_to_str(type, typevals, "0x%04X - unknown"));
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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, is_ppp);
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offset += sizeof(flags_and_ver);
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proto_tree_add_uint(gre_tree, hf_gre_proto, NullTVB, offset, sizeof(type), 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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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for (;;) {
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sre_af = pntohs(pd + offset);
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proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(guint16),
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"Address family: %u", sre_af);
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offset += sizeof(guint16);
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proto_tree_add_text(gre_tree, NullTVB, offset, 1,
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"SRE offset: %u", pd[offset++]);
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sre_length = pd[offset];
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proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(guint8),
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"SRE length: %u", sre_length);
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offset += sizeof(guint8);
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if (sre_af == 0 && sre_length == 0)
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break;
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offset += sre_length;
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}
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}
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switch (type) {
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case GRE_PPP:
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next_tvb = tvb_new_subset(pi.compat_top_tvb, offset, -1, -1);
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dissect_ppp(next_tvb, &pi, tree);
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break;
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case GRE_IP:
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dissect_ip(pd, offset, fd, tree);
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break;
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case GRE_WCCP:
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if (is_wccp2) {
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proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(guint32), "WCCPv2 Data");
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offset += 4;
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}
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dissect_ip(pd, offset, fd, tree);
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break;
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case GRE_IPX:
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dissect_ipx(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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break;
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}
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}
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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, NullTVB, offset, 2,
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"Flags and version: %#04x", 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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, NullTVB, 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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{ &hf_gre_proto,
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{ "Protocol Type", "gre.proto", FT_UINT16, BASE_HEX, VALS(typevals), 0x0,
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"The protocol that is GRE encapsulated"}
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},
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};
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static gint *ett[] = {
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&ett_gre,
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&ett_gre_flags,
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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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proto_register_subtree_array(ett, array_length(ett));
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}
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void
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proto_reg_handoff_gre(void)
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{
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dissector_add("ip.proto", IP_PROTO_GRE, dissect_gre);
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}
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