nexmon – Rev 1
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/* packet-msdp.c
* Routines for Multicast Source Discovery Protocol (MSDP) dissection.
* draft-ietf-msdp-spec-10.txt
*
* Copyright 2001, Heikki Vatiainen <hessu@cs.tut.fi>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* 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
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/to_str.h>
void proto_register_msdp(void);
void proto_reg_handoff_msdp(void);
/* MSDP message types. The messages are TLV (Type-Length-Value) encoded */
enum { MSDP_SA = 1,
MSDP_SA_REQ,
MSDP_SA_RSP,
MSDP_KEEP_ALIVE,
MSDP_NOTIFICATION,
/* These are only assigned in MSDP spec. Their use is specified
* elsewhere */
MSDP_TRACE_IN_PROGRESS,
MSDP_TRACE_REPLY
};
static const value_string msdp_types[] = {
{ MSDP_SA, "IPv4 Source-Active" },
{ MSDP_SA_REQ, "IPv4 Source-Active Request" },
{ MSDP_SA_RSP, "IPv4 Source-Active Response" },
{ MSDP_KEEP_ALIVE, "KeepAlive" },
{ MSDP_NOTIFICATION, "Notification" },
{ MSDP_TRACE_IN_PROGRESS, "MSDP traceroute in progress" },
{ MSDP_TRACE_REPLY, "MSDP traceroute reply" },
{ 0, NULL },
};
/* Error codes */
enum { MESSAGE_HEADER_ERROR = 1,
SA_REQUEST_ERROR,
SA_MESSAGE_SA_RESPONSE_ERROR,
HOLD_TIMER_EXPIRED,
FSM_ERROR,
NOTIFICATION,
CEASE
};
static const value_string error_vals[] = {
{ MESSAGE_HEADER_ERROR, "Message Header Error" },
{ SA_REQUEST_ERROR, "SA-Request Error" },
{ SA_MESSAGE_SA_RESPONSE_ERROR, "SA-Message/SA-Response Error" },
{ HOLD_TIMER_EXPIRED, "Hold Timer Expired" },
{ FSM_ERROR, "Finite State Machine Error" },
{ NOTIFICATION, "Notification" },
{ CEASE, "Cease" },
{ 0, NULL },
};
/* Message Header Error subcodes */
static const value_string hdr_error_vals[] = {
{ 0, "Unspecific" },
{ 2, "Bad Message Length" },
{ 3, "Bad Message Type" },
{ 0, NULL },
};
/* SA-Request Error subcodes (the O-bit is always clear) */
static const value_string sa_req_error_vals[] = {
{ 0, "Unspecific" },
{ 1, "Invalid Group" },
{ 0, NULL },
};
/* SA-Message/SA-Response Error subcodes */
static const value_string sa_msg_error_vals[] = {
{ 0, "Unspecific" },
{ 1, "Invalid Entry Count" },
{ 2, "Invalid RP Address" },
{ 3, "Invalid Group Address" },
{ 4, "Invalid Source Address" },
{ 5, "Invalid Sprefix Length" },
{ 6, "Looping SA (Self is RP)" },
{ 7, "Unknown Encapsulation" },
{ 8, "Administrative Scope Boundary Violated" },
{ 0, NULL },
};
/* Finite State Machine Error subcodes (the O-bit is always clear) */
static const value_string fsm_error_vals[] = {
{ 0, "Unspecific" },
{ 1, "Unexpected Message Type FSM Error" },
{ 0, NULL },
};
/*
* Hold Timer Expired subcodes (the O-bit is always clear):
* Notification subcodes (the O-bit is always clear):
* Cease subcodes (the O-bit is always clear):
*
* These have only "Unspecific" specified.
*/
static const value_string sa_unspec_error_vals[] = {
{ 0, "Unspecific" },
{ 0, NULL },
};
/* Initialize the protocol and registered fields */
static int proto_msdp = -1;
static int hf_msdp_type = -1;
static int hf_msdp_length = -1;
static int hf_msdp_sa_entry_count = -1;
static int hf_msdp_sa_rp_addr = -1;
static int hf_msdp_sa_reserved = -1;
static int hf_msdp_sa_sprefix_len = -1;
static int hf_msdp_sa_group_addr = -1;
static int hf_msdp_sa_src_addr = -1;
static int hf_msdp_sa_req_res = -1;
static int hf_msdp_sa_req_group = -1;
static int hf_msdp_not_o = -1;
static int hf_msdp_not_error = -1;
static int hf_msdp_not_error_sub = -1;
static int hf_msdp_not_group_address = -1;
static int hf_msdp_not_rp_address = -1;
static int hf_msdp_not_source_address = -1;
static int hf_msdp_not_res = -1;
static int hf_msdp_not_entry_count = -1;
static int hf_msdp_not_sprefix_len = -1;
static int hf_msdp_tlv_contents = -1;
static int hf_msdp_trailing_junk = -1;
static int hf_msdp_unknown_encap = -1;
static int hf_msdp_unknown_data = -1;
static gint ett_msdp = -1;
static gint ett_msdp_sa_entry = -1;
static gint ett_msdp_sa_enc_data = -1;
static gint ett_msdp_not_data = -1;
static dissector_handle_t ip_handle;
static void
dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
int *offset, int len);
static void
dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len);
static int
dissect_msdp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
proto_item *ti;
proto_tree *msdp_tree;
int offset;
guint8 type;
guint16 length;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "MSDP");
col_set_str(pinfo->cinfo, COL_INFO, val_to_str_const(tvb_get_guint8(tvb, 0),
msdp_types,
"<Unknown MSDP message type>"));
ti = proto_tree_add_item(tree, proto_msdp, tvb, 0, -1, ENC_NA);
msdp_tree = proto_item_add_subtree(ti, ett_msdp);
offset = 0;
while (tvb_reported_length_remaining(tvb, offset) >= 3) {
type = tvb_get_guint8(tvb, offset);
length = tvb_get_ntohs(tvb, offset + 1);
if (length < 3)
break;
proto_tree_add_uint(msdp_tree, hf_msdp_type, tvb, offset, 1, type);
proto_tree_add_uint(msdp_tree, hf_msdp_length, tvb, offset + 1, 2, length);
offset += 3;
length -= 3;
switch (type) {
case MSDP_SA:
case MSDP_SA_RSP:
dissect_msdp_sa(tvb, pinfo, msdp_tree, &offset,
length);
break;
case MSDP_SA_REQ:
proto_tree_add_item(msdp_tree, hf_msdp_sa_req_res, tvb, offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(msdp_tree, hf_msdp_sa_req_group, tvb, offset + 1, 4, ENC_BIG_ENDIAN);
offset += 5;
break;
case MSDP_NOTIFICATION:
dissect_msdp_notification(tvb, pinfo, msdp_tree, &offset, length);
break;
default:
if (length > 0)
proto_tree_add_item(msdp_tree, hf_msdp_tlv_contents, tvb, offset, length, ENC_NA);
offset += length;
break;
}
}
if (tvb_reported_length_remaining(tvb, offset) > 0)
proto_tree_add_item(msdp_tree, hf_msdp_trailing_junk, tvb, offset, -1, ENC_NA);
return tvb_captured_length(tvb);
}
/* Both Source-Active and Source-Active Response have the same format
* with one exception. Encapsulated multicast data is not allowed in
* SA Response.
*/
static void dissect_msdp_sa(tvbuff_t *tvb, packet_info *pinfo,
proto_tree *tree, int *offset, int length)
{
guint8 entries;
if (length < 1)
return;
entries = tvb_get_guint8(tvb, *offset);
proto_tree_add_uint(tree, hf_msdp_sa_entry_count, tvb, *offset, 1, entries);
*offset += 1;
length -= 1;
if (length < 4) {
*offset += length;
return;
}
proto_tree_add_item(tree, hf_msdp_sa_rp_addr, tvb, *offset, 4, ENC_BIG_ENDIAN);
*offset += 4;
length -= 4;
/* Put each of the (S,G) entries in their own subtree.
* This is probably visually better.
*/
while (entries-- > 0) {
proto_tree *entry_tree;
if (length < 12) {
*offset += length;
return;
}
entry_tree = proto_tree_add_subtree_format(tree, tvb, *offset, 12, ett_msdp_sa_entry, NULL,
"(S,G) block: %s/%u -> %s",
tvb_ip_to_str(tvb, *offset + 8),
tvb_get_guint8(tvb, *offset + 3),
tvb_ip_to_str(tvb, *offset + 4));
proto_tree_add_item(entry_tree, hf_msdp_sa_reserved, tvb, *offset, 3, ENC_BIG_ENDIAN);
*offset += 3;
length -= 3;
proto_tree_add_item(entry_tree, hf_msdp_sa_sprefix_len, tvb, *offset, 1, ENC_BIG_ENDIAN);
*offset += 1;
length -= 1;
proto_tree_add_item(entry_tree, hf_msdp_sa_group_addr, tvb, *offset, 4, ENC_BIG_ENDIAN);
*offset += 4;
length -= 4;
proto_tree_add_item(entry_tree, hf_msdp_sa_src_addr, tvb, *offset, 4, ENC_BIG_ENDIAN);
*offset += 4;
length -= 4;
}
/*
* Check if an encapsulated multicast IPv4 packet follows
*/
if (length > 0) {
proto_tree *enc_tree;
gint available_length, reported_length;
tvbuff_t *next_tvb;
enc_tree = proto_tree_add_subtree_format(tree, tvb, *offset, length,
ett_msdp_sa_enc_data, NULL, "Encapsulated IPv4 packet: %u bytes",
length);
available_length = tvb_captured_length_remaining(tvb, *offset);
reported_length = tvb_reported_length_remaining(tvb, *offset);
DISSECTOR_ASSERT(available_length >= 0);
DISSECTOR_ASSERT(reported_length >= 0);
if (available_length > reported_length)
available_length = reported_length;
if (available_length > length)
available_length = length;
if (reported_length > length)
reported_length = length;
next_tvb = tvb_new_subset(tvb, *offset, available_length,
reported_length);
/* Set the information columns read-only so that they
* reflect the MSDP packet rather than the
* encapsulated packet.
*/
col_set_writable(pinfo->cinfo, COL_INFO, FALSE);
call_dissector(ip_handle, next_tvb, pinfo, enc_tree);
}
*offset += length;
return;
}
/* Note: updates *offset */
static void add_notification_data_ipv4addr(tvbuff_t *tvb, proto_tree *tree, int *offset, int hf_addr)
{
proto_tree_add_item(tree, hf_msdp_not_res, tvb, *offset, 3, ENC_BIG_ENDIAN);
*offset += 3;
proto_tree_add_item(tree, hf_addr, tvb, *offset, 4, ENC_BIG_ENDIAN);
*offset += 4;
return;
}
static void dissect_msdp_notification(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int *offset, guint16 tlv_len)
{
guint8 error, error_sub;
const value_string *vals;
proto_tree_add_item(tree, hf_msdp_not_o, tvb, *offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(tree, hf_msdp_not_error, tvb, *offset, 1, ENC_BIG_ENDIAN);
error = tvb_get_guint8(tvb, *offset);
error &= 0x7F; /* Error is 7-bit field. O-bit is bit 8 */
*offset += 1;
/* Depending on the Error Code, we collect the correct
* value_strings for the Error subcode
*/
switch (error) {
case MESSAGE_HEADER_ERROR:
vals = hdr_error_vals;
break;
case SA_REQUEST_ERROR:
vals = sa_req_error_vals;
break;
case SA_MESSAGE_SA_RESPONSE_ERROR:
vals = sa_msg_error_vals;
break;
case FSM_ERROR:
vals = fsm_error_vals;
break;
case HOLD_TIMER_EXPIRED:
case NOTIFICATION:
case CEASE:
vals = sa_unspec_error_vals;
break;
default:
vals = sa_unspec_error_vals;
break;
}
error_sub = tvb_get_guint8(tvb, *offset);
proto_tree_add_uint_format_value(tree, hf_msdp_not_error_sub, tvb, *offset, 1,
error_sub, "%s (%u)",
val_to_str_const(error_sub, vals, "<Unknown Error subcode>"),
error_sub);
*offset += 1;
/* Do switch again, this time to dissect the data portion
* correctly. Ugly.
*/
switch (error) {
case SA_REQUEST_ERROR:
add_notification_data_ipv4addr(tvb, tree, offset, hf_msdp_not_group_address);
break;
case SA_MESSAGE_SA_RESPONSE_ERROR:
if (error_sub == 0) {
break;
} else if (error_sub == 1) {
proto_tree_add_item(tree, hf_msdp_not_entry_count, tvb, *offset, 1, ENC_BIG_ENDIAN);
*offset += 1;
break;
} else if (error_sub == 2) {
add_notification_data_ipv4addr(tvb, tree, offset, hf_msdp_not_rp_address);
break;
} else if (error_sub == 3 || error_sub == 8) {
add_notification_data_ipv4addr(tvb, tree, offset, hf_msdp_not_group_address);
break;
} else if (error_sub == 4) {
add_notification_data_ipv4addr(tvb, tree, offset, hf_msdp_not_source_address);
break;
} else if (error_sub == 5) {
proto_tree_add_item(tree, hf_msdp_not_sprefix_len, tvb, *offset, 1, ENC_BIG_ENDIAN);
*offset += 1;
break;
} else if (error_sub == 6) {
/* No break, causes fall through to next label */
} else if (error_sub == 7) {
proto_tree_add_item(tree, hf_msdp_unknown_encap, tvb, *offset, tlv_len - 5, ENC_NA);
*offset += tlv_len - 5;
break;
} else {
proto_tree_add_item(tree, hf_msdp_unknown_data, tvb, *offset, tlv_len - 5, ENC_NA);
*offset += tlv_len - 5;
break;
}
/* Fall through */
case MESSAGE_HEADER_ERROR:
case NOTIFICATION: {
tvbuff_t *next_tvb;
/* Data contains the message that had an error. Even a
* broken Notification message causes a Notification
* message with Error Code set to Notification to be
* sent back.
*/
next_tvb = tvb_new_subset_remaining(tvb, *offset);
dissect_msdp(next_tvb, pinfo, tree, NULL);
}
break;
case FSM_ERROR:
case HOLD_TIMER_EXPIRED:
case CEASE:
/* Do nothing. These contain no data */
break;
default:
if (tlv_len - 5 > 0)
proto_tree_add_item(tree, hf_msdp_unknown_data, tvb, *offset, tlv_len - 5, ENC_NA);
*offset += tlv_len - 5;
break;
}
return;
}
void
proto_register_msdp(void)
{
static hf_register_info hf[] = {
{ &hf_msdp_type,
{ "Type", "msdp.type",
FT_UINT8, BASE_DEC, VALS(msdp_types), 0,
"MSDP TLV type", HFILL }
},
{ &hf_msdp_length,
{ "Length", "msdp.length",
FT_UINT16, BASE_DEC, NULL, 0,
"MSDP TLV Length", HFILL }
},
{ &hf_msdp_sa_entry_count,
{ "Entry Count", "msdp.sa.entry_count",
FT_UINT8, BASE_DEC, NULL, 0,
"MSDP SA Entry Count", HFILL }
},
{ &hf_msdp_sa_rp_addr,
{ "RP Address", "msdp.sa.rp_addr",
FT_IPv4, BASE_NONE, NULL, 0,
"Active source's RP address", HFILL }
},
{ &hf_msdp_sa_reserved,
{ "Reserved", "msdp.sa.reserved",
FT_UINT24, BASE_HEX, NULL, 0,
"Transmitted as zeros and ignored by a receiver", HFILL }
},
{ &hf_msdp_sa_sprefix_len,
{ "Sprefix len", "msdp.sa.sprefix_len",
FT_UINT8, BASE_DEC, NULL, 0,
"The route prefix length associated with source address", HFILL }
},
{ &hf_msdp_sa_group_addr,
{ "Group Address", "msdp.sa.group_addr",
FT_IPv4, BASE_NONE, NULL, 0,
"The group address the active source has sent data to", HFILL }
},
{ &hf_msdp_sa_src_addr,
{ "Source Address", "msdp.sa.src_addr",
FT_IPv4, BASE_NONE, NULL, 0,
"The IP address of the active source", HFILL }
},
{ &hf_msdp_sa_req_res,
{ "Reserved", "msdp.sa_req.res",
FT_UINT8, BASE_HEX, NULL, 0,
"Transmitted as zeros and ignored by a receiver", HFILL }
},
{ &hf_msdp_sa_req_group,
{ "Group Address", "msdp.sa_req.group_addr",
FT_IPv4, BASE_NONE, NULL, 0,
"The group address the MSDP peer is requesting", HFILL }
},
{ &hf_msdp_not_o,
{ "Open-bit", "msdp.not.o",
FT_UINT8, BASE_HEX, NULL, 0x80,
"If clear, the connection will be closed", HFILL }
},
{ &hf_msdp_not_error,
{ "Error Code", "msdp.not.error",
FT_UINT8, BASE_DEC, VALS(error_vals), 0x7F,
"Indicates the type of Notification", HFILL }
},
{ &hf_msdp_not_error_sub,
{ "Error subcode", "msdp.not.error_sub",
FT_UINT8, BASE_DEC, NULL, 0,
NULL, HFILL }
},
{ &hf_msdp_not_group_address,
{ "Group address", "msdp.not.group_address",
FT_IPv4, BASE_NONE, NULL, 0,
"Group address in Notification messages", HFILL }
},
{ &hf_msdp_not_rp_address,
{ "RP address", "msdp.not.rp_address",
FT_IPv4, BASE_NONE, NULL, 0,
"RP address in Notification messages", HFILL }
},
{ &hf_msdp_not_source_address,
{ "Source address", "msdp.not.source_address",
FT_IPv4, BASE_NONE, NULL, 0,
"Source address in Notification messages", HFILL }
},
{ &hf_msdp_not_res,
{ "Reserved", "msdp.not.res",
FT_UINT24, BASE_HEX, NULL, 0,
"Reserved field in Notification messages", HFILL }
},
{ &hf_msdp_not_entry_count,
{ "Entry Count", "msdp.not.entry_count",
FT_UINT24, BASE_HEX, NULL, 0,
"Entry Count in Notification messages", HFILL }
},
{ &hf_msdp_not_sprefix_len,
{ "Sprefix len", "msdp.not.sprefix_len",
FT_UINT8, BASE_DEC, NULL, 0,
"Source prefix length in Notification messages", HFILL }
},
{ &hf_msdp_tlv_contents,
{ "TLV contents", "msdp.tlv_contents",
FT_BYTES, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_msdp_trailing_junk,
{ "Trailing junk", "msdp.trailing_junk",
FT_BYTES, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_msdp_unknown_encap,
{ "Packet with unknown encapsulation", "msdp.unknown_encap",
FT_BYTES, BASE_NONE, NULL, 0,
NULL, HFILL }
},
{ &hf_msdp_unknown_data,
{ "Unknown data", "msdp.unknown_data",
FT_BYTES, BASE_NONE, NULL, 0,
NULL, HFILL }
},
};
static gint *ett[] = {
&ett_msdp,
&ett_msdp_sa_entry,
&ett_msdp_sa_enc_data,
&ett_msdp_not_data,
};
proto_msdp = proto_register_protocol("Multicast Source Discovery Protocol",
"MSDP", "msdp");
proto_register_field_array(proto_msdp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
void
proto_reg_handoff_msdp(void)
{
dissector_handle_t msdp_handle;
msdp_handle = create_dissector_handle(dissect_msdp, proto_msdp);
dissector_add_uint("tcp.port", 639, msdp_handle);
ip_handle = find_dissector_add_dependency("ip", proto_msdp);
}
/*
* Editor modelines
*
* Local Variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=8 tabstop=8 expandtab:
* :indentSize=8:tabSize=8:noTabs=true:
*/