* Routines for the Generic Routing Encapsulation (GRE) protocol
* Brad Robel-Forrest <brad.robel-forrest@watchguard.com>
*
- * $Id: packet-gre.c,v 1.29 2000/11/19 08:53:57 guy Exp $
+ * $Id: packet-gre.c,v 1.50 2002/01/21 07:36:34 guy Exp $
*
* Ethereal - Network traffic analyzer
- * By Gerald Combs <gerald@zing.org>
+ * By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
- *
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
#include <netinet/in.h>
#endif
#include <glib.h>
-#include "packet.h"
-#include "packet-ip.h"
-#include "packet-ipx.h"
+#include <epan/packet.h>
+#include "packet-wccp.h"
+#include "in_cksum.h"
+#include "etypes.h"
+#include "greproto.h"
+#include "ipproto.h"
+
+/*
+ * See RFC 1701 "Generic Routing Encapsulation (GRE)", RFC 1702
+ * "Generic Routing Encapsulation over IPv4 networks", RFC 2637
+ * "Point-to-Point Tunneling Protocol (PPTP)", RFC 2784 "Generic
+ * Routing Encapsulation (GRE)", and RFC 2890 "Key and Sequence
+ * Number Extensions to GRE".
+ */
static int proto_gre = -1;
static int hf_gre_proto = -1;
static gint ett_gre = -1;
static gint ett_gre_flags = -1;
+static gint ett_gre_wccp2_redirect_header = -1;
+
+static dissector_table_t gre_dissector_table;
+static dissector_handle_t data_handle;
/* bit positions for flags in header */
#define GH_B_C 0x8000
#define GH_R_FLAGS 0x00F8
#define GH_B_VER 0x0007
-#define GRE_PPP 0x880B
-#define GRE_IP 0x0800
-#define GRE_WCCP 0x883E
-#define GRE_IPX 0x8137
-
-static void add_flags_and_ver(proto_tree *, guint16, int, int);
+static void add_flags_and_ver(proto_tree *, guint16, tvbuff_t *, int, int);
+static void dissect_gre_wccp2_redirect_header(tvbuff_t *, int, proto_tree *);
static const value_string typevals[] = {
- { GRE_PPP, "PPP" },
- { GRE_IP, "IP" },
- { GRE_WCCP, "WCCP"},
- { GRE_IPX, "IPX"},
- { 0, NULL }
+ { ETHERTYPE_PPP, "PPP" },
+ { ETHERTYPE_IP, "IP" },
+ { GRE_WCCP, "WCCP"},
+ { ETHERTYPE_IPX, "IPX"},
+ { ETHERTYPE_ETHBRIDGE, "Transparent Ethernet bridging" },
+ { GRE_FR, "Frame Relay"},
+ { 0, NULL }
};
-static dissector_handle_t ip_handle;
-static dissector_handle_t ppp_handle;
-
static void
-dissect_gre(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
-
- guint16 flags_and_ver = pntohs(pd + offset);
- guint16 type = pntohs(pd + offset + sizeof(flags_and_ver));
+dissect_gre(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+ int offset = 0;
+ guint16 flags_and_ver;
+ guint16 type;
+ gboolean is_ppp = FALSE;
+ gboolean is_wccp2 = FALSE;
+ guint len = 4;
+ proto_item *ti;
+ proto_tree *gre_tree = NULL;
guint16 sre_af;
guint8 sre_length;
tvbuff_t *next_tvb;
- OLD_CHECK_DISPLAY_AS_DATA(proto_gre, pd, offset, fd, tree);
+ flags_and_ver = tvb_get_ntohs(tvb, offset);
+ type = tvb_get_ntohs(tvb, offset + sizeof(flags_and_ver));
+
+ if (check_col(pinfo->cinfo, COL_PROTOCOL))
+ col_set_str(pinfo->cinfo, COL_PROTOCOL, "GRE");
- if (check_col(fd, COL_PROTOCOL))
- col_set_str(fd, COL_PROTOCOL, "GRE");
-
- if (check_col(fd, COL_INFO)) {
- col_add_fstr(fd, COL_INFO, "Encapsulated %s",
- val_to_str(type, typevals, "0x%04X (unknown)"));
+ if (check_col(pinfo->cinfo, COL_INFO)) {
+ col_add_fstr(pinfo->cinfo, COL_INFO, "Encapsulated %s",
+ val_to_str(type, typevals, "0x%04X (unknown)"));
}
-
- if (IS_DATA_IN_FRAME(offset) && tree) {
- gboolean is_ppp = FALSE;
- gboolean is_wccp2 = FALSE;
- proto_item * ti;
- proto_tree * gre_tree;
- guint len = 4;
-
- if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R)
- len += 4;
- if (flags_and_ver & GH_B_K)
+
+ if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R)
+ len += 4;
+ if (flags_and_ver & GH_B_K)
+ len += 4;
+ if (flags_and_ver & GH_B_S)
+ len += 4;
+ switch (type) {
+
+ case ETHERTYPE_PPP:
+ if (flags_and_ver & GH_P_A)
len += 4;
- if (flags_and_ver & GH_B_S)
+ is_ppp = TRUE;
+ break;
+
+ case GRE_WCCP:
+ /* WCCP2 puts an extra 4 octets into the header, but uses the same
+ encapsulation type; if it looks as if the first octet of the packet
+ isn't the beginning of an IPv4 header, assume it's WCCP2. */
+ if ((tvb_get_guint8(tvb, offset + sizeof(flags_and_ver) + sizeof(type)) & 0xF0) != 0x40) {
len += 4;
- switch (type) {
-
- case GRE_PPP:
- if (flags_and_ver & GH_P_A)
- len += 4;
- is_ppp = TRUE;
- break;
-
- case GRE_WCCP:
- /* WCCP2 apparently puts an extra 4 octets into the header, but uses
- the same encapsulation type; if it looks as if the first octet of
- the packet isn't the beginning of an IPv4 header, assume it's
- WCCP2. */
- if ((pd[offset + sizeof(flags_and_ver) + sizeof(type)] & 0xF0) != 0x40) {
- len += 4;
- is_wccp2 = TRUE;
- }
- break;
+ is_wccp2 = TRUE;
}
+ break;
+ }
- ti = proto_tree_add_protocol_format(tree, proto_gre, NullTVB, offset, len,
+ if (tree) {
+ ti = proto_tree_add_protocol_format(tree, proto_gre, tvb, offset, len,
"Generic Routing Encapsulation (%s)",
val_to_str(type, typevals, "0x%04X - unknown"));
gre_tree = proto_item_add_subtree(ti, ett_gre);
- add_flags_and_ver(gre_tree, flags_and_ver, offset, is_ppp);
+ add_flags_and_ver(gre_tree, flags_and_ver, tvb, offset, is_ppp);
+ }
+ offset += sizeof(flags_and_ver);
+
+ if (tree) {
+ proto_tree_add_uint(gre_tree, hf_gre_proto, tvb, offset, sizeof(type), type);
+ }
+ offset += sizeof(type);
- offset += sizeof(flags_and_ver);
+ if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) {
+ if (tree) {
+ guint length, reported_length;
+ vec_t cksum_vec[1];
+ guint16 cksum, computed_cksum;
- proto_tree_add_uint(gre_tree, hf_gre_proto, NullTVB, offset, sizeof(type), type);
- offset += sizeof(type);
+ cksum = tvb_get_ntohs(tvb, offset);
+ length = tvb_length(tvb);
+ reported_length = tvb_reported_length(tvb);
+ if ((flags_and_ver & GH_B_C) && !pinfo->fragmented
+ && length >= reported_length) {
+ /* The Checksum Present bit is set, and the packet isn't part of a
+ fragmented datagram and isn't truncated, so we can checksum it. */
- if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) {
- guint16 checksum = pntohs(pd + offset);
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(checksum),
- "Checksum: %u", checksum);
- offset += sizeof(checksum);
+ cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, reported_length);
+ cksum_vec[0].len = reported_length;
+ computed_cksum = in_cksum(cksum_vec, 1);
+ if (computed_cksum == 0) {
+ proto_tree_add_text(gre_tree, tvb, offset, 2,
+ "Checksum: 0x%04x (correct)", cksum);
+ } else {
+ proto_tree_add_text(gre_tree, tvb, offset, 2,
+ "Checksum: 0x%04x (incorrect, should be 0x%04x)",
+ cksum, in_cksum_shouldbe(cksum, computed_cksum));
+ }
+ } else {
+ proto_tree_add_text(gre_tree, tvb, offset, 2,
+ "Checksum: 0x%04x", cksum);
+ }
}
-
- if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) {
- guint16 rtoffset = pntohs(pd + offset);
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(rtoffset),
- "Offset: %u", rtoffset);
- offset += sizeof(rtoffset);
+ offset += 2;
+ }
+
+ if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) {
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, 2,
+ "Offset: %u", tvb_get_ntohs(tvb, offset));
}
+ offset += 2;
+ }
- if (flags_and_ver & GH_B_K) {
- if (is_ppp) {
- guint16 paylen;
- guint16 callid;
-
- paylen = pntohs(pd + offset);
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(paylen),
- "Payload length: %u", paylen);
- offset += sizeof(paylen);
-
- callid = pntohs(pd + offset);
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(callid),
- "Call ID: %u", callid);
- offset += sizeof(callid);
+ if (flags_and_ver & GH_B_K) {
+ if (is_ppp) {
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, 2,
+ "Payload length: %u", tvb_get_ntohs(tvb, offset));
}
- else {
- guint32 key = pntohl(pd + offset);
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(key),
- "Key: %u", key);
- offset += sizeof(key);
+ offset += 2;
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, 2,
+ "Call ID: %u", tvb_get_ntohs(tvb, offset));
}
+ offset += 2;
}
+ else {
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, 4,
+ "Key: %u", tvb_get_ntohl(tvb, offset));
+ }
+ offset += 4;
+ }
+ }
- if (flags_and_ver & GH_B_S) {
- guint32 seqnum = pntohl(pd + offset);
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(seqnum),
- "Sequence number: %u", seqnum);
- offset += sizeof(seqnum);
+ if (flags_and_ver & GH_B_S) {
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, 4,
+ "Sequence number: %u", tvb_get_ntohl(tvb, offset));
}
+ offset += 4;
+ }
- if (is_ppp && flags_and_ver & GH_P_A) {
- guint32 acknum = pntohl(pd + offset);
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(acknum),
- "Acknowledgement number: %u", acknum);
- offset += sizeof(acknum);
+ if (is_ppp && flags_and_ver & GH_P_A) {
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, 4,
+ "Acknowledgement number: %u", tvb_get_ntohl(tvb, offset));
}
+ offset += 4;
+ }
- if (flags_and_ver & GH_B_R) {
- for (;;) {
- sre_af = pntohs(pd + offset);
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(guint16),
+ if (flags_and_ver & GH_B_R) {
+ for (;;) {
+ sre_af = tvb_get_ntohs(tvb, offset);
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, sizeof(guint16),
"Address family: %u", sre_af);
- offset += sizeof(guint16);
- proto_tree_add_text(gre_tree, NullTVB, offset, 1,
- "SRE offset: %u", pd[offset++]);
- sre_length = pd[offset];
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(guint8),
+ }
+ offset += sizeof(guint16);
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, 1,
+ "SRE offset: %u", tvb_get_guint8(tvb, offset));
+ }
+ offset += sizeof(guint8);
+ sre_length = tvb_get_guint8(tvb, offset);
+ if (tree) {
+ proto_tree_add_text(gre_tree, tvb, offset, sizeof(guint8),
"SRE length: %u", sre_length);
- offset += sizeof(guint8);
- if (sre_af == 0 && sre_length == 0)
- break;
- offset += sre_length;
}
+ offset += sizeof(guint8);
+ if (sre_af == 0 && sre_length == 0)
+ break;
+ offset += sre_length;
}
+ }
- switch (type) {
- case GRE_PPP:
- old_call_dissector(ppp_handle, pd, offset, fd, tree);
- break;
- case GRE_IP:
- old_call_dissector(ip_handle, pd, offset, fd, tree);
- break;
- case GRE_WCCP:
- if (is_wccp2) {
- proto_tree_add_text(gre_tree, NullTVB, offset, sizeof(guint32), "WCCPv2 Data");
- offset += 4;
- }
- old_call_dissector(ip_handle, pd, offset, fd, tree);
- break;
- case GRE_IPX:
- next_tvb = tvb_create_from_top(offset);
- dissect_ipx(next_tvb, &pi, tree);
- break;
- default:
- next_tvb = tvb_create_from_top(offset);
- dissect_data(next_tvb, 0, &pi, gre_tree);
- break;
+ if (type == GRE_WCCP) {
+ if (is_wccp2) {
+ if (tree)
+ dissect_gre_wccp2_redirect_header(tvb, offset, gre_tree);
+ offset += 4;
}
}
+
+ /* If the S bit is not set, this packet might not have a payload, so
+ check whether there's any data left, first.
+
+ XXX - the S bit isn't in RFC 2784, which deprecates that bit
+ and some other bits in RFC 1701 and says that they should be
+ zero for RFC 2784-compliant GRE; as such, the absence of the
+ S bit doesn't necessarily mean there's no payload. */
+ if (!(flags_and_ver & GH_B_S)) {
+ if (tvb_reported_length_remaining(tvb, offset) <= 0)
+ return; /* no payload */
+ }
+ next_tvb = tvb_new_subset(tvb, offset, -1, -1);
+ if (!dissector_try_port(gre_dissector_table, type, next_tvb, pinfo, tree))
+ call_dissector(data_handle,next_tvb, pinfo, gre_tree);
}
static void
-add_flags_and_ver(proto_tree *tree, guint16 flags_and_ver, int offset, int is_ppp) {
-
+add_flags_and_ver(proto_tree *tree, guint16 flags_and_ver, tvbuff_t *tvb,
+ int offset, int is_ppp)
+{
proto_item * ti;
proto_tree * fv_tree;
int nbits = sizeof(flags_and_ver) * 8;
- ti = proto_tree_add_text(tree, NullTVB, offset, 2,
+ ti = proto_tree_add_text(tree, tvb, offset, 2,
"Flags and version: %#04x", flags_and_ver);
fv_tree = proto_item_add_subtree(ti, ett_gre_flags);
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_boolean_bitfield(flags_and_ver, GH_B_C, nbits,
"Checksum", "No checksum"));
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_boolean_bitfield(flags_and_ver, GH_B_R, nbits,
"Routing", "No routing"));
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_boolean_bitfield(flags_and_ver, GH_B_K, nbits,
"Key", "No key"));
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_boolean_bitfield(flags_and_ver, GH_B_S, nbits,
"Sequence number", "No sequence number"));
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_boolean_bitfield(flags_and_ver, GH_B_s, nbits,
"Strict source route", "No strict source route"));
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_numeric_bitfield(flags_and_ver, GH_B_RECUR, nbits,
"Recursion control: %u"));
if (is_ppp) {
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_boolean_bitfield(flags_and_ver, GH_P_A, nbits,
"Acknowledgment number", "No acknowledgment number"));
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_numeric_bitfield(flags_and_ver, GH_P_FLAGS, nbits,
"Flags: %u"));
}
else {
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_numeric_bitfield(flags_and_ver, GH_R_FLAGS, nbits,
"Flags: %u"));
}
- proto_tree_add_text(fv_tree, NullTVB, offset, sizeof(flags_and_ver), "%s",
+ proto_tree_add_text(fv_tree, tvb, offset, sizeof(flags_and_ver), "%s",
decode_numeric_bitfield(flags_and_ver, GH_B_VER, nbits,
"Version: %u"));
}
+
+static void
+dissect_gre_wccp2_redirect_header(tvbuff_t *tvb, int offset, proto_tree *tree)
+{
+ proto_item * ti;
+ proto_tree * rh_tree;
+ guint8 rh_flags;
+
+ ti = proto_tree_add_text(tree, tvb, offset, 4, "Redirect header");
+ rh_tree = proto_item_add_subtree(ti, ett_gre_wccp2_redirect_header);
+
+ rh_flags = tvb_get_guint8(tvb, offset);
+ proto_tree_add_text(rh_tree, tvb, offset, 1, "%s",
+ decode_boolean_bitfield(rh_flags, 0x80, 8,
+ "Dynamic service", "Well-known service"));
+ proto_tree_add_text(rh_tree, tvb, offset, 1, "%s",
+ decode_boolean_bitfield(rh_flags, 0x40, 8,
+ "Alternative bucket used", "Alternative bucket not used"));
+
+ proto_tree_add_text(rh_tree, tvb, offset + 1, 1, "Service ID: %s",
+ val_to_str(tvb_get_guint8(tvb, offset + 1), service_id_vals, "Unknown (0x%02X)"));
+ if (rh_flags & 0x40)
+ proto_tree_add_text(rh_tree, tvb, offset + 2, 1, "Alternative bucket index: %u",
+ tvb_get_guint8(tvb, offset + 2));
+ proto_tree_add_text(rh_tree, tvb, offset + 3, 1, "Primary bucket index: %u",
+ tvb_get_guint8(tvb, offset + 3));
+}
void
proto_register_gre(void)
static hf_register_info hf[] = {
{ &hf_gre_proto,
{ "Protocol Type", "gre.proto", FT_UINT16, BASE_HEX, VALS(typevals), 0x0,
- "The protocol that is GRE encapsulated"}
+ "The protocol that is GRE encapsulated", HFILL }
},
};
static gint *ett[] = {
&ett_gre,
&ett_gre_flags,
+ &ett_gre_wccp2_redirect_header,
};
- proto_gre = proto_register_protocol("Generic Routing Encapsulation", "gre");
+ proto_gre = proto_register_protocol("Generic Routing Encapsulation",
+ "GRE", "gre");
proto_register_field_array(proto_gre, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
+
+ /* subdissector code */
+ gre_dissector_table = register_dissector_table("gre.proto",
+ "GRE protocol type", FT_UINT16, BASE_HEX);
}
void
proto_reg_handoff_gre(void)
{
- old_dissector_add("ip.proto", IP_PROTO_GRE, dissect_gre);
+ dissector_handle_t gre_handle;
- /*
- * Get handles for the IP and PPP dissectors.
- */
- ip_handle = find_dissector("ip");
- ppp_handle = find_dissector("ppp");
+ gre_handle = create_dissector_handle(dissect_gre, proto_gre);
+ dissector_add("ip.proto", IP_PROTO_GRE, gre_handle);
+ data_handle = find_dissector("data");
}
git.samba.org / obnox / wireshark / wip.git / blobdiff