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/* packet-cisco-mcp.c
* Routines for the disassembly of Cisco's MCP (Miscabling Protocol)
*
* Copyright 2019 Joerg Mayer (see AUTHORS file)
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
TODO:
- Figure out the meaning of more types
- Figure out the hash calculation
- Display Value in TLV toplevel item where appropriate
Specs: No specs available
No header
Sequence of TLVs of format
Type (1 byte)
Length (1 byte)
Value (Length bytes of Data)
Patent:
http://www.freepatentsonline.com/20150124643.pdf
Documentation:
https://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/application-centric-infrastructure/white-paper-c11-737909.pdf
https://unofficialaciguide.com/2018/03/27/using-mcp-miscabling-protocol-for-aci/
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/to_str.h>
#include <epan/cisco_pid.h>
void proto_register_mcp(void);
void proto_reg_handoff_mcp(void);
static int proto_mcp = -1;
/* TLV header */
static int hf_mcp_tlv_type = -1;
static int hf_mcp_tlv_length = -1;
/* Values */
static int hf_mcp_1 = -1;
static int hf_mcp_switchid = -1;
static int hf_mcp_3 = -1;
static int hf_mcp_ifindex = -1;
static int hf_mcp_timestamp = -1;
static int hf_mcp_hmac = -1;
// static int hf_mcp_end = -1;
static int hf_mcp_unknown = -1;
static expert_field ei_mcp_short_tlv = EI_INIT;
static expert_field ei_mcp_trailing_bytes = EI_INIT;
static expert_field ei_mcp_unexpected_tlv_length = EI_INIT;
static gint ett_mcp = -1;
static gint ett_mcp_tlv_header = -1;
#define PROTO_SHORT_NAME "MCP"
#define PROTO_LONG_NAME "Miscabling Protocol"
typedef enum {
MCP_TYPE_1 = 1, // Len=4, perhaps version or fabric-id
MCP_TYPE_SWITCHID = 2, // Len=4,
MCP_TYPE_3 = 3, // Len=12,
MCP_TYPE_IFINDEX = 4, // Len=4,
MCP_TYPE_TIMESTAMP = 5, // Len=4,
MCP_TYPE_HMAC = 6, // Len=20, Guessing, possibly SHA1
MCP_TYPE_END = 7 // Len=0
} mcp_type_t;
static const value_string mcp_type_vals[] = {
{ MCP_TYPE_1, "Unknown1"},
{ MCP_TYPE_SWITCHID, "SwitchID"},
{ MCP_TYPE_3, "Unknown3"},
{ MCP_TYPE_IFINDEX, "IfIndex"},
{ MCP_TYPE_TIMESTAMP, "Timestamp"},
{ MCP_TYPE_HMAC, "HMAC?"},
{ MCP_TYPE_END, "End"},
{ 0, NULL }
};
static int
dissect_mcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
proto_item *ti;
proto_tree *mcp_tree;
proto_tree *tlv_tree;
guint32 offset = 0;
gboolean last = FALSE;
guint8 tlv_type;
guint16 tlv_length;
guint16 data_length = tvb_reported_length_remaining(tvb, offset);;
guint32 switchid, ifindex, timestamp;
gchar* timestamp_str;
col_set_str(pinfo->cinfo, COL_PROTOCOL, PROTO_SHORT_NAME);
col_set_str(pinfo->cinfo, COL_INFO, "");
ti = proto_tree_add_item(tree, proto_mcp, tvb, offset, -1,
ENC_NA);
mcp_tree = proto_item_add_subtree(ti, ett_mcp);
/* No header whatsoever, just a plain sequence of TLVs */
while (offset < data_length && !last) {
if (data_length - offset < 2) {
proto_tree_add_expert_format(mcp_tree, pinfo, &ei_mcp_short_tlv, tvb,
offset, 4, "Too few bytes left for TLV (%u < 2)", data_length - offset);
break;
}
tlv_type = tvb_get_guint8(tvb, offset);
tlv_length = tvb_get_guint8(tvb, offset + 1);
tlv_tree = proto_tree_add_subtree_format(mcp_tree, tvb, offset, tlv_length + 2,
ett_mcp_tlv_header, NULL, "TLV length %d, type %d = %s",
tlv_length, tlv_type, val_to_str(tlv_type, mcp_type_vals, "Unknown (0x%02x)"));
proto_tree_add_uint(tlv_tree, hf_mcp_tlv_type, tvb, offset, 1, tlv_type);
offset += 1;
proto_tree_add_uint(tlv_tree, hf_mcp_tlv_length, tvb, offset, 1, tlv_length);
if (tlv_length > (data_length - (offset + 1))) {
proto_tree_add_expert_format(tlv_tree, pinfo, &ei_mcp_short_tlv, tvb,
offset, 1, "TLV length (%u) passes end of packet", tlv_length);
break;
}
offset += 1;
switch (tlv_type) {
case MCP_TYPE_1:
if (tlv_length == 4) {
proto_tree_add_item(tlv_tree, hf_mcp_1, tvb, offset, tlv_length, ENC_BIG_ENDIAN);
} else {
proto_tree_add_expert_format(mcp_tree, pinfo, &ei_mcp_unexpected_tlv_length, tvb,
offset, tlv_length, "Expected value length differs from seen length (%u != %u)",
4, tlv_length);
}
break;
case MCP_TYPE_SWITCHID:
if (tlv_length == 4) {
proto_tree_add_item_ret_uint(tlv_tree, hf_mcp_switchid, tvb, offset, tlv_length, ENC_BIG_ENDIAN, &switchid);
proto_item_append_text(tlv_tree, ": %u", switchid);
col_append_fstr(pinfo->cinfo, COL_INFO, "SwID/%u ", switchid);
} else {
proto_tree_add_expert_format(mcp_tree, pinfo, &ei_mcp_unexpected_tlv_length, tvb,
offset, tlv_length, "Expected value length differs from seen length (%u != %u)",
4, tlv_length);
}
break;
case MCP_TYPE_3:
proto_tree_add_item(tlv_tree, hf_mcp_3, tvb, offset, tlv_length, ENC_NA);
break;
case MCP_TYPE_IFINDEX:
if (tlv_length == 4) {
proto_tree_add_item_ret_uint(tlv_tree, hf_mcp_ifindex, tvb, offset, tlv_length, ENC_BIG_ENDIAN, &ifindex);
proto_item_append_text(tlv_tree, ": 0x%08x", ifindex);
col_append_fstr(pinfo->cinfo, COL_INFO, "ifIdx/0x%08x ", ifindex);
} else {
proto_tree_add_expert_format(mcp_tree, pinfo, &ei_mcp_unexpected_tlv_length, tvb,
offset, tlv_length, "Expected value length differs from seen length (%u != %u)",
4, tlv_length);
}
break;
case MCP_TYPE_TIMESTAMP:
if (tlv_length == 4) {
proto_tree_add_item(tlv_tree, hf_mcp_timestamp, tvb, offset, tlv_length, ENC_TIME_SECS|ENC_BIG_ENDIAN);
timestamp = tvb_get_ntohl(tvb, offset);
timestamp_str = abs_time_secs_to_str(wmem_packet_scope(), timestamp, ABSOLUTE_TIME_LOCAL, TRUE);
proto_item_append_text(tlv_tree, ": %s", timestamp_str);
col_append_fstr(pinfo->cinfo, COL_INFO, "time/%s ", timestamp_str);
} else {
proto_tree_add_expert_format(mcp_tree, pinfo, &ei_mcp_unexpected_tlv_length, tvb,
offset, tlv_length, "Expected value length differs from seen length (%u != %u)",
4, tlv_length);
}
break;
case MCP_TYPE_HMAC:
if (tlv_length == 20) {
proto_tree_add_item(tlv_tree, hf_mcp_hmac, tvb, offset, tlv_length, ENC_NA);
} else {
proto_tree_add_expert_format(mcp_tree, pinfo, &ei_mcp_unexpected_tlv_length, tvb,
offset, tlv_length, "Expected value length differs from seen length (%u != %u)",
20, tlv_length);
}
break;
case MCP_TYPE_END:
last = TRUE;
if (tlv_length != 0) {
proto_tree_add_expert_format(mcp_tree, pinfo, &ei_mcp_unexpected_tlv_length, tvb,
offset, tlv_length, "Expected value length differs from seen length (%u != %u)",
0, tlv_length);
}
break;
default:
proto_tree_add_item(tlv_tree, hf_mcp_unknown, tvb, offset, tlv_length, ENC_NA);
break;
}
offset += tlv_length;
}
if (offset < data_length) {
proto_tree_add_expert(mcp_tree, pinfo, &ei_mcp_trailing_bytes, tvb, offset,
data_length - offset);
}
return tvb_captured_length(tvb);
}
void
proto_register_mcp(void)
{
static hf_register_info hf[] = {
/* TLV header (aka TL) */
{ &hf_mcp_tlv_type,
{ "TLV type", "mcp.tlv.type", FT_UINT8, BASE_DEC, VALS(mcp_type_vals),
0x0, NULL, HFILL }},
{ &hf_mcp_tlv_length,
{ "TLV length", "mcp.tlv.length", FT_UINT16, BASE_DEC, NULL,
0x0, NULL, HFILL }},
/* TLV data (aka V) */
{ &hf_mcp_1,
{ "Type1", "mcp.type1", FT_UINT32, BASE_DEC, NULL,
0x0, NULL, HFILL }},
{ &hf_mcp_switchid,
{ "Switch ID", "mcp.switchid", FT_UINT32, BASE_DEC, NULL,
0x0, "Originating Switch", HFILL }},
{ &hf_mcp_3,
{ "Type3", "mcp.type3", FT_BYTES, BASE_NONE, NULL,
0x0, NULL, HFILL }},
{ &hf_mcp_ifindex,
{ "IfIndex", "mcp.ifindex", FT_UINT32, BASE_HEX, NULL,
0x0, NULL, HFILL }},
{ &hf_mcp_timestamp,
{ "Timestamp", "mcp.timestamp", FT_ABSOLUTE_TIME, ABSOLUTE_TIME_LOCAL, NULL,
0x0, NULL, HFILL }},
{ &hf_mcp_hmac,
{ "HMAC(?)", "mcp.hmac", FT_BYTES, BASE_NONE, NULL,
0x0, NULL, HFILL }},
{ &hf_mcp_unknown,
{ "Unknown", "mcp.unknown", FT_BYTES, BASE_NONE, NULL,
0x0, NULL, HFILL }},
};
static gint *ett[] = {
&ett_mcp,
&ett_mcp_tlv_header,
};
static ei_register_info ei[] = {
{ &ei_mcp_short_tlv,
{ "mcp.short_tlv", PI_MALFORMED, PI_ERROR,
"TLV is too short", EXPFILL }},
{ &ei_mcp_trailing_bytes,
{ "mcp.trailing_bytes", PI_PROTOCOL, PI_WARN,
"Trailing bytes after last TLV", EXPFILL }},
{ &ei_mcp_unexpected_tlv_length,
{ "mcp.unexpected_tlv_length", PI_PROTOCOL, PI_WARN,
"Expected Value length differs from seen length", EXPFILL }},
};
expert_module_t* expert_mcp;
proto_mcp = proto_register_protocol(PROTO_LONG_NAME, PROTO_SHORT_NAME, "mcp");
proto_register_field_array(proto_mcp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_mcp = expert_register_protocol(proto_mcp);
expert_register_field_array(expert_mcp, ei, array_length(ei));
}
void
proto_reg_handoff_mcp(void)
{
dissector_handle_t mcp_handle;
mcp_handle = create_dissector_handle(dissect_mcp, proto_mcp);
dissector_add_uint("llc.cisco_pid", CISCO_PID_MCP, mcp_handle);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
|
